Ändra sökning
Avgränsa sökresultatet
44454647 2301 - 2347 av 2347
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 2301.
    Zhang, Ping
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Nordlund, Erling
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Swan, Graham
    Rock Mechanics and Mine Design, Sudbury, Canada.
    Yi, Changping
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Velocity Amplification of Seismic Waves Through Parallel Fractures Near a Free Surface in Fractured Rock: A Theoretical Study2019Ingår i: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 52, nr 1, s. 199-213Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To determine the dynamic demand for support design under rockburst conditions, one of the most important issues is the prediction of ground motion parameters at the site of interest. Field monitoring has shown that the peak ground motion at the surface of an excavation in fractured rock is preferentially amplified compared to the motion in solid rock at a similar distance from the source. However, the traditional scaling laws used in rock support design do not account for the effect of free surface (excavation) and fracturing of rock. Recent studies have shown that high ground motion might be generated when a seismic wave crosses through fractures near a free surface in fractured rocks which is very complex and is not well understood. In this paper, particle velocity amplification was theoretically studied by investigating the dynamic interaction between seismic wave and multiple fractures near a free surface using the method of characteristics and the displacement discontinuity model. A harmonic load was applied on a model with a fractured zone near a free surface to investigate this phenomenon. After the harmonic wave propagated normally through multiple parallel fractures, the velocity amplification factor (VAF) was calculated as a function of the ratio of the magnitude of the peak particle velocity at the free surface of the model to the peak input velocity. The VAF can be as high as 3.77 and varies depending on the state of the fractured rock and the characteristics of the seismic wave. Parameter studies were conducted to investigate the effects of seismic load and multiple fractures on wave propagation, especially in terms of the wave frequency, the fracture spacing, the number of fractures and the stiffness of fractures. The results have proved that the interaction of the seismic wave and multiple fractures near the free surface strongly influences the ground motion. Quantitative relationships between the various influential factors and the corresponding VAF were developed. It is anticipated that such relationships can provide criteria to improve the current design procedures and help mining engineers to improve their rock support practice for rockburst-prone areas.

  • 2302.
    Zhang, Ping
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Swan, Graham
    Rock Mechanics and Mine Design, Canada.
    Nordlund, Erling
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    1D numerical simulation of velocity amplification of P-waves travelling through fractured rock near a free surface2015Ingår i: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 115, nr 11, s. 1121-1126Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The most widely used support design damage criterion for rockburst-prone mines is based upon kinetic energy, which is proportional to the square of the ejection velocity and is commonly expressed in terms of peak particle velocity (PPV). Field monitoring and back-analyses have shown that ejection velocities of the order of 10 m/s and higher can result from seismic events of moderate magnitude. Such velocities are much higher than those predicted using PPV obtained from scaling laws. It has also been found that the peak ground motion (i.e. PPV) on the surface of an excavation is preferentially amplified (by four-to tenfold) compared to the motion in solid rock at a similar distance from the source. However, the wave propagation and interaction processes involved within the fractured rock in generating high ground motion are very complex and are not well understood at this time. In this paper, velocity amplification was investigated by modelling the dynamic interaction between fractured rock and a free surface using a 2D discontinuum-based numerical program, UDEC (Universal Distinct Element Code). A 1D model with a fractured zone was used to represent the fractured rock. Velocity amplification, quantified by PPV, predicted at the free end of the model was 2.0-3.6 times higher than the input velocity. It was found that the wave frequency, fracture stiffness, fracture spacing, and thickness of fractured zone are the main factors that affect the velocity amplification. The results have proved that the interaction of the seismic wave and multiple fractures near the free surface strongly influences the ground motion

  • 2303.
    Zhang, Ping
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Yi, Changping
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Nordlund, Erling
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Shirzadegan, Shahin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Nyberg, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Malmgren, Lars
    Mining Technology R and D, LKAB Kiruna Mine.
    Nordqvist, Anders
    LKAB.
    Numerical back-analysis of simulated rockburst field tests by using coupled numerical technique2013Ingår i: Ground Support 2013: Proceedings of the Seventh International Symposium on Ground Support in Mining and Underground Construction / [ed] Yves Potvin; B.G.H. Brady, Perth, Australia: Australian Center for Geomechanics , 2013, s. 565-581Konferensbidrag (Refereegranskat)
    Abstract [en]

    In order to assess the capacity of ground support systems when submitted to dynamic loading, simulated rockburst tests utilizing blasting have been performed for many years in different countries with limited success. In general, the blasts need to be carefully designed in order to reach the goal; however, different blast layouts (e.g. blasthole angle, burden) have been used based on researcher’s experience without conducting detailed analyses, the exception being a field test by CSIR. Recently, field trials have been conducted at the LKAB Kiirunavaara underground mine with some unexpected results which show that either the whole tested panel was destroyed or only a few fractures were formed without any ejections being observed. The aim of this paper is to investigate the failure mechanism in the simulated rockburst tests and improve the blast design by back-analyzing the test results using a coupled numerical modeling technique. The blast was simulated by using finite element method (LS-DYNA) and the dynamic interaction between the blasting generated waves and the opening was simulated by using discrete element modeling (UDEC) with the dynamic input from LS-DYNA. The numerical modeling showed that blasting can create both radial fractures radiating from the blasthole and fractures parallel or sub-parallel to the surface of the tested panel caused by reflected tensile stress waves. By comparing the results of the numerical modeling with the measured data, it is shown that the collapse failure was mainly controlled by the creation of a cone-shaped area formed by radial fractures and the burden seems to be a critical factor. In order to obtain fractures caused by reflected tensile stress waves and reduce blasting induced radial fractures, 2 parallel blastholes are suggested with larger burden (> 5 m) for future tests. Furthermore, the limitation of the current numerical modeling has also been discussed. The coupled numerical technique has shown its advantage when simulating blasting as well as interaction between waves and opening and it can thus be used as a tool for extrapolating results from simulated rockburst experiments if detailed geological structure and ground support system can be incorporated in the model and the model can be well calibrated.

  • 2304. Zhang, Ping
    et al.
    Yin, J.J.
    Hunan University.
    Nordlund, Erling
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Li, N.
    Xi'an University of Technology.
    Determination and verification of the longitudinal deformation profile in a horse-shoe shaped tunnel using two-stage excavation2008Ingår i: MassMin 2008: Proceedings of the 5th International Conference and Exhibition on Mass Mining, Lulea, Sweden 9-11 June 2008 / [ed] Håkan Schunnesson; Erling Nordlund, Luleå: Luleå tekniska universitet, 2008, s. 845-854Konferensbidrag (Refereegranskat)
  • 2305.
    Zhang, Shuangsheng
    et al.
    School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou, China.Xuzhou Urban Water Resources Management Office, Xuzhou, China.
    Liu, Hanhu
    School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou, China..
    Qiang, Jing
    School of Mathematics, China University of Mining and Technology, Xuzhou, China.
    Gao, Hongze
    GHD Services, Inc, Waterloo, Ontario, Canada.
    Galar, Diego
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Lin, Jing
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Optimization of Well Position and Sampling Frequency for Groundwater Monitoring and Inverse Identification of Contamination Source Conditions Using Bayes’ Theorem2019Ingår i: CMES - Computer Modeling in Engineering & Sciences, ISSN 1526-1492, E-ISSN 1526-1506, Vol. 119, nr 2, s. 373-394Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Coupling Bayes’ Theorem with a two-dimensional (2D) groundwater solute advection-diffusion transport equation allows an inverse model to be established to identify a set of contamination source parameters including source intensity (M ), release location ( X0 , Y0) and release time (T0), based on monitoring well data. To address the issues of insufficient monitoring wells or weak correlation between monitoring data and model parameters, a monitoring well design optimization approach was developed based on the Bayesian formula and information entropy. To demonstrate how the model works, an exemplar problem with an instantaneous release of a contaminant in a confined groundwater aquifer was employed. The information entropy of the model parameters posterior distribution was used as a criterion to evaluate the monitoring data quantity index. The optimal monitoring well position and monitoring frequency were solved by the two-step Monte Carlo method and differential evolution algorithm given a known well monitoring locations and monitoring events. Based on the optimized monitoring well position and sampling frequency, the contamination source was identified by an improved Metropolis algorithm using the Latin hypercube sampling approach. The case study results show that the following parameters were obtained: 1) the optimal monitoring well position (D) is at (445, 200); and 2) the optimal monitoring frequency (Δt) is 7, providing that the monitoring events is set as 5 times. Employing the optimized monitoring well position and frequency, the mean errors of inverse modeling results in source parameters (M, X0 ,Y0 ,T0 ) were 9.20%, 0.25%, 0.0061%, and 0.33%, respectively. The optimized monitoring well position and sampling frequency can effectively safeguard the inverse modeling results in identifying the contamination source parameters. It was also learnt that the improved Metropolis-Hastings algorithm (a Markov chain Monte Carlo method) can make the inverse modeling result independent of the initial sampling points and achieves an overall optimization, which significantly improved the accuracy and numerical stability of the inverse modeling results.

  • 2306.
    Zhang, Xiaoge
    et al.
    Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, USA.
    Mahadevan, Sankaran
    Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, USA..
    Goebel, Kai
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik. Systems Sciences Lab, Palo Alto Research Center, Palo Alto, CA, USA.
    Network Reconfiguration for Increasing Transportation System Resilience Under Extreme Events2019Ingår i: Risk Analysis, ISSN 0272-4332, E-ISSN 1539-6924, Vol. 39, nr 9, s. 2054-2075Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Evacuating residents out of affected areas is an important strategy for mitigating the impact of natural disasters. However, the resulting abrupt increase in the travel demand during evacuation causes severe congestions across the transportation system, which thereby interrupts other commuters' regular activities. In this article, a bilevel mathematical optimization model is formulated to address this issue, and our research objective is to maximize the transportation system resilience and restore its performance through two network reconfiguration schemes: contraflow (also referred to as lane reversal) and crossing elimination at intersections. Mathematical models are developed to represent the two reconfiguration schemes and characterize the interactions between traffic operators and passengers. Specifically, traffic operators act as leaders to determine the optimal system reconfiguration to minimize the total travel time for all the users (both evacuees and regular commuters), while passengers act as followers by freely choosing the path with the minimum travel time, which eventually converges to a user equilibrium state. For each given network reconfiguration, the lower-level problem is formulated as a traffic assignment problem (TAP) where each user tries to minimize his/her own travel time. To tackle the lower-level optimization problem, a gradient projection method is leveraged to shift the flow from other nonshortest paths to the shortest path between each origin-destination pair, eventually converging to the user equilibrium traffic assignment. The upper-level problem is formulated as a constrained discrete optimization problem, and a probabilistic solution discovery algorithm is used to obtain the near-optimal solution. Two numerical examples are used to demonstrate the effectiveness of the proposed method in restoring the traffic system performance.

  • 2307.
    Zhang, Z. X.
    et al.
    Luleå tekniska universitet.
    Kou, S. Q.
    Luleå tekniska universitet.
    Jiang, L. G.
    University of Science and Technology, Beijing.
    Lindqvist, Per-Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Effects of loading rate on rock fracture: fracture characteristics and energy partitioning2000Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 37, nr 5, s. 745-762Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By means of the Scanning Electron Microscope (SEM), an examination was performed of the fracture surfaces (including their vertical sections) of both Fangshan gabbro and Fangshan marble specimens fractured at the loading rates k = 10-2 ≈ 106 MPa m1/2 s-1. The results showed that one or more branching cracks near the fracture surfaces of dynamic rock specimens were clear and the cracks increased with increasing loading rates. However, such branching cracks were rarely seen near the static fracture surfaces. In addition, with the aid of the Split Hopkinson Pressure Bar (SHPB) testing system and a high-speed framing camera, the energy partitioning in the dynamic fracture process of a short rod (SR) rock specimen was analysed quantitatively. The total energy WL absorbed by an SR specimen in the dynamic fracture process mainly consisted of the fracture and damage energy WFD and the kinetic energy WK of flying fragments. The energies WL and WK could be quantitatively calculated through stress wave measurement and high-speed photography in the SHPB testing system. Thus, the fracture and damage energy WFD could be obtained. The results showed that: (1) the energy WK increased with an increase in the impact speed of the striker bar or the loading rate; (2) the energy WFD for dynamic rock fracture was markedly greater than that for static rock fracture, and the WFD increased with an increase in the impact speed of the striker bar or the loading rate; and (3) the value WL/WB (WB is the energy input into the loading system) in the case of dynamic fracture is much lower than that in the case of static fracture. In addition, the ratio decreases with an increase in the loading rate or the impact speed of the striker bar. This means that the energy utilisation decreases when the loading rate or the impact speed of the striker bar rises. Finally, some application problems are discussed in the paper.

  • 2308.
    Zhang, Z X
    et al.
    Luleå tekniska universitet.
    Kou, S Q
    Luleå tekniska universitet.
    Lindqvist, Per-Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Measurements of cutter forces and cutter temperature of boring machine in Äspö Hard Rock Laboratory2001Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    I denna rapport presenteras både testmetoder och resultat från mätning av verktygskrafter och temperatur under fullborrning av schakt i Äspölaboratoriet.För att bedöma deformationer som induceras i axlarna på verktygen (cutters) och för rätt val av kraftgivare genomfördes numeriska beräkningar. Dessa visade att vanliga trådtöjningsgivare kunde användas. Ett system med oberoende belastning i tre riktningar för kalibrering i laboratorium av kraftgivare monterades för att lösa problemet med koppling mellan givare under fältmätningen. Med hjälp av det därpå utvecklade mätsystemet, som testades i laboratorium, mättes normalkraft, tangentiell kraft och sidokraft på två verktyg i fält. Dessutom mättes temperaturen i axeln på ett av verktygen i fronten på borrhuvudet. Efter mätning av verktygskrafter och temperatur, uttogs borrkärnor från botten och väggar på det schakt som borrats. Proverna sågades, polerades och undersöktes i svepelektronmikroskop. Längden på sprickor som uppstått under verktygen mättes och ett approximativt samband mellan längden på mediansprickor och relevanta verktygskrafter kunde skapas. Detta samband jämfördes med teoretiska samband som etablerats tidigare. Slutligen kunde, utgående från de erhållna resultaten, den spruckna zonen omkring schaktet beskrivas. Resultaten visar att: (1) två olika sprickzoner kan utskiljas: en i väggarna och en i botten på schaktet. Djupet på den uppspruckna zonen i botten är mycket större än i väggarna på schaktet beroende på att den maximala normalkraften på verktyg riktat framåt (front cutter) alltid är mycket högre än på verktyget mot väggen (gauge cutter). (2) Varje sprickzon inkluderar dels en kraftigt uppsprucken zon dels glest liggande, långa mediansprickor. (3) Från mätningen av fyra bergprover har maximala djupet på mediansprickor i schaktbotten uppmätts till 27,1 mm och maximala djupet på den kraftigt uppspruckna zonen till 2,5-3,0 mm.

  • 2309. Zhang, Z. X.
    et al.
    Kou, S. Q.
    Yu, J
    Yu, Y
    Jiang, L. G.
    Lindqvist, Per-Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Effects of loading rate on rock fracture1999Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 36, nr 5, s. 597-611Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By means of a wedge loading applied to a short-rod rock fracture specimen tested with the MTS 810 or SHPB (split Hopkinson pressure bar), the fracture toughness of Fangshan gabbro and Fangshan marble was measured over a wide range of loading rates, =10−2–106 MPa m1/2 s−1. In order to determine the dynamic fracture toughness of the rock as exactly as possible, the dynamic Moiré method and strain–gauge method were used in determining the critical time of dynamic fracture. The testing results indicated that the critical time was generally shorter than the transmitted wave peak time, and the differences between the two times had a weak increasing tendency with loading rates. The experimental results for rock fracture showed that the static fracture toughness KIc of the rock was nearly a constant, but the dynamic fracture toughness KId of the rock (≥104 MPa m1/2 s−1) increased with the loading rate, i.e. log(KId)=a log +b. Macroobservations for fractured rock specimens indicated that, in the section (which was perpendicular to the fracture surface) of a specimen loaded by a dynamic load, there was clear crack branching or bifurcation, and the higher the loading rate was, the more branching cracks occurred. Furthermore, at very high loading rates (≥106 MPa m1/2 s−1) the rock specimen was broken into several fragments rather than only two halves. However, for a statically fractured specimen there was hardly any crack branching. Finally, some applications of this investigation in engineering practice are discussed.

  • 2310.
    Zhang, Z X
    et al.
    Luleå tekniska universitet.
    Yu, J
    University of Science and Technology, Beijing.
    Kou, S.Q.
    Luleå tekniska universitet.
    Lindqvist, Per-Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Effects of high temperatures on dynamic rock fracture2001Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 38, nr 2, s. 211-225Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dynamic fracture toughness of Fangshan Gabbro and Fangshan Marble subjected to high temperature was measured by means of the split Hopkinson pressure bar (SHPB) system. The specimens for measuring the fracture toughness were manufactured according to the requirements for the Short Rod (SR) specimen suggested by ISRM. Two cases were investigated: (1) the SR specimens of the gabbro and marble were fractured at high temperature (100-330 degrees C), and (2) the specimens of the rocks were first pre-heat-treated at 200 degrees C for the marble and 600 degrees C for the gabbro, and then fractured at room temperature. The experimental results showed that under dynamic loading the fracture toughness of both the gabbro and the marble tested in the above-mentioned cases increased with increasing loading rates. The relationship between the fracture toughness and the loading rates in the two cases is similar to that obtained in the room temperature environment, i.e., without high temperature. (This is defined as the third case.) It can be concluded that temperature variation affects the dynamic fracture toughness of the two rocks to a limited extent within the temperature ranges tested. This is different from the results obtained under the static loading condition. Furthermore, by means of the scanning electronic microscope (SEM), the vertical sections of the fracture surfaces for some gabbro specimens were examined. In addition, the fractal dimensions of the fracture surfaces of some specimens were measured by means of fractal geometry. The results showed that under dynamic loading: (1) macro-crack branching near the fracture surfaces was universal; (2) the fractal dimensions increased with increasing loading rates; (3) in the sections of the specimens tested at high temperature there were many micro-cracks that were probably induced by thermal cracking. On the basis of the above macro- and micro-experimental investigation, an energy analysis of the process of dynamic rock fracture was performed. The results showed that the energy utilisation in dynamic fracture was much lower than that in static fracture.

  • 2311.
    Zhang, Zhi-qiang
    et al.
    Xi’an University of Technology, Xi’an, P.R. China.
    Li, Ning
    Xi’an University of Technology, Xi’an, P.R. China.
    Zhang, Ping
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Han, S.
    Xi’an University of Technology, Xi’an, P.R. China.
    Effect of fault on tunnel stability with different distribution2013Ingår i: Global View of Engineering Geology and the Environment: International Symposium & 9th Asian Regional Conference of IAEG / [ed] Faquan Wu; Shengwen Qi, London: CRC Press, Taylor & Francis Group , 2013, s. 279-285Konferensbidrag (Refereegranskat)
    Abstract [en]

    For tunnel engineering, the fault that locates near tunnel always plays an important role on the stability of the surrounding rock mass and the safety of the supporting system. To investigate the influence of the fault on the tunnel stability, systematic numerical experiments are carried out via the FINAL code. Through these numerical experiment results, the displacement and the distribution of the stress in surrounding rock mass are analyzed for these cases of the different locations and dips of fault around tunnel periphery, and the stress in the sprayed concrete layer are analyzed as well. To simulate the characteristics of the fault located in the rock mass, the COJO element, embedded in the FINAL code, is used in all numerical experiments. The quantized results reflecting the rules of the change for the displacement, stress, plastic region in the surrounding rock mass are obtained also in this paper.

  • 2312.
    Zhang, Zongxian
    Luleå tekniska universitet.
    Laboratory studies of dynamic rock fracture and in-situ measurements of cutter forces for a boring machine2001Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    All forms of rock failure usually happen within a very wide range of loading rates covering static and dynamic loading. Since rock failure always results from fracture - the propagation of one or more cracks- the first part of the thesis is focused on laboratory studies of the influences of loading rates on rock fracture. This part has mainly investigated macro/micro fracture characteristics of rock, energy partitioning in the process of rock fracture, and the influences of high temperatures on rock fracture. In the second part of the thesis, the research has dealt with in-situ measurements of the cutter forces and cutter temperatures of a boring machine. Then a number of core rock samples were taken from the borehole. After that, the cracks induced by mechanical boring were examined by using a scanning electron microscope (SEM). Finally, an approximate relationship between the length of the medium cracks and the respective normal forces measured in-situ was established.

  • 2313.
    Zhang, Zongxian
    et al.
    Luleå University of Technology.
    Kou, Shaoquan
    Luleå University of Technology.
    Lindqvist, Per-Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    In-situ measurements of cutter forces on boring machine at Äspö Hard Rock Laboratory. Part 2: Characteristics of cutter forces and examination of cracks generated2003Ingår i: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 36, nr 1, s. 63-83Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By means of spectral analysis, the measured normal forces, tangential forces, and side forces acting on two button cutters on the boring machine in Äspö Hard Rock Laboratory were analysed and the basic characteristics of the cutter forces were determined. After the measurements of the cutter forces, some rock core samples were taken from the bottom and the wall of the test borehole. These samples were cut, polished, and examined by means of a Scanning Electron Microscope (SEM). The lengths of the major cracks in the rock samples were measured, and a relation between the length of the median cracks and the relevant cutter forces was investigated.

  • 2314.
    Zhang, Zongxian
    et al.
    Luleå University of Technology.
    Kou, Shaoquan
    Luleå University of Technology.
    Lindqvist, Per-Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    In-situ measurements of TBM cutter temperature in Äspö Hard Rock Laboratory, Sweden2001Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 38, nr 4, s. 585-590Artikel i tidskrift (Refereegranskat)
  • 2315.
    Zhang, Zongxian
    et al.
    Luleå University of Technology.
    Kou, Shaoquan
    Luleå University of Technology.
    Tan, Xiangchun
    Luleå University of Technology.
    Lindqvist, Per-Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    In-situ measurements of cutter forces on boring machine at Äspö Hard Rock Laboratory. Part 1: Laboratory calibration and in-situ measurements2003Ingår i: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 36, nr 1, s. 39-61Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the testing methods used and the results obtained in an investigation of the cutter forces on a Boretec DS 1.6 boring machine during field boring in Äspö Hard Rock Laboratory. Two button cutters, one front cutter and one gauge cutter, were used in the field measurements. A total of 6 strain gauges were bonded on the shaft of each cutter. And each group of two gauges was used to measure a one-orthogonal cutter force component, i.e. the normal force, tangential force, and side force, respectively. In order to measure the cutter forces successfully, a telemetry system composed of a transmitter and a receiver was employed to transfer the signals from the strain gauges to a computer.A three-direction-loading system was employed in the laboratory calibration so as to solve the force-coupling problem appearing in the cutter force measurements. Correspondingly, a mathematical treatment of the force-coupling problem was performed. Then, by means of the established testing system, which was proved successful in the laboratory, the normal force, tangential force, and side force of the two button cutters on the boring machine were measured in the field. In addition, the penetration rate, thrust, and rotation speed of the boring machine were also recorded in the field. The results show the following. (1) A force-coupling phenomenon really exists and it should be considered. (2) All three directional force components always show quite a high peak value every few seconds. (3) The cutter forces of the front cutter are always much larger than the respective cutter forces of the gauge cutter. Moreover, as expected, the normal force of each cutter is much larger than the tangential force and side force of the cutter in question.

  • 2316.
    Zhang, Zongxian
    et al.
    Luleå University of Technology.
    Yu, J.
    Luleå University of Technology.
    Kou, Shaoquan
    Luleå University of Technology.
    Lindqvist, Per-Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    On study of influences of loading rate on fractal dimensions of fracture surfaces in Gabbro2001Ingår i: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 34, nr 3, s. 235-242Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Studies of the effects of loading rates on rock fracture were performed for decades. However, the previous work on static or dynamic rock fracture was mainly limited to a macro-experimental study. The present investigation measures the fractal dimensions of the fracture surfaces of the gabbro specimens fractured at various loading rates covering static and dynamic loading, and explores the relationship between the fractal dimensions and the fracture toughness of the rock.

  • 2317.
    Zhang, Z.X.
    Luleå tekniska universitet.
    An empirical relation between mode I fracture toughness and the tensile strength of rock2002Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 39, nr 3, s. 401-406Artikel i tidskrift (Refereegranskat)
  • 2318.
    Zhang, Z.X.
    Luleå tekniska universitet.
    Estimate of loading rate for a TBM machine based on measured cutter forces2004Ingår i: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 37, nr 3, s. 239-248Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Various aspects of a tunnel boring machines (TBM) were presented. The loading rate of a TBM machine can be estimated on the basis of its cutter force measurements. The method can also be used to estimate the loading rate of other similar rock breakage machines. On the basis of the cutter forces measured in the field, the loading rate of the Boretech D1.6 boring machine was estimated. Results show that the loading rate of the machine is within a typical quasi-static loading

  • 2319.
    Zhang, Z.X.
    et al.
    Luleå tekniska universitet.
    Kou, S.Q.
    Luleå tekniska universitet.
    Lindqvist, Per-Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Fracture behaviour of rock under dynamic loading1999Ingår i: Comptes-rendus / 9 Congrès international de mécanique de roches, Paris, France 1999 / [ed] Gerard Vouille; Pierre Berest, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1999, Vol. 2, s. 1127-1130Konferensbidrag (Refereegranskat)
  • 2320. Zhang, Z.X.
    et al.
    Kou, S.Q.
    Lindqvist, Per-Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Measurements of cutter forces for a TBM machine in Aspo underground2000Ingår i: Pacific rocks 2000: "rock around the rim". Proceedings of the 4th North American Rock Mechanics Symposium / [ed] Jami Girard, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 2000, Vol. 4, s. 11-17Konferensbidrag (Refereegranskat)
  • 2321. Zhang, Z.X.
    et al.
    Kou, S.Q.
    Lindqvist, Per-Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Yu, J.
    University of Science and Technology of China.
    Jiang, L.G.
    University of Science and Technology of China.
    Dynamic fracture behaviour of rock at high temperatures1999Ingår i: Rock mechanics for industry: proceedings of the 37th US Rock Mechanics Symposium /Vail/Colorado/USA/6-9 June 1999 / [ed] Bernard Arnadei, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1999, s. 325-331Konferensbidrag (Refereegranskat)
  • 2322.
    Zhang, Z.X.
    et al.
    LKAB, Research & Development, 983 81 Malmberget.
    Lindqvist, Per-Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Naarttijärvi, Torbjörn
    LKAB, Research & Development, 983 81 Malmberget.
    Wikström, K.
    LKAB, Research & Development, 983 81 Malmberget.
    A feasibility study on controlling ground vibrations caused by blasts in Malmberget underground mine2010Ingår i: Fragblast, ISSN 1385-514X, E-ISSN 1744-4977, Vol. 8, nr 1, s. 3-21Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to control or reduce the ground vibrations caused by underground blasts in Malmberget mine, a number of blast tests were carried out during production blasts and a series of single shot waveforms were obtained. Then the single shot waveforms from the same ring or different rings were analysed and compared with each other. The results showed that the single shots are reproducible, meaning that the ground vibrations caused by underground blasts can be controlled by means of the interference of the vibration waveforms measured. Finally, a formal test using electronic detonators and employing an optimum delay time of 8 ms was done in production. The test for an 11-borehole ring shows that the maximum vertical ground vibrations are reduced to the maximum vertical vibrations of a single shot. Particularly, the total vibration history for the 11-borehole-ring blast is shortened to about 200 ms over a velocity of 2 mm/s. However, the total vibration history of a normal production blast of 11-borehole ring is always 1400 ms over a velocity of 2 mm/s, namely the total vibration time of a production blast can be reduced to one seventh of that of the common production blasts by using the vibration control method. This indicates that the vibration control method introduced in the paper is feasible for underground mining blasts

  • 2323.
    Zhu, Huiming
    et al.
    College of Business Administration, Hunan University.
    Guan, Haoyun
    College of Business Administration, Hunan University.
    Lin, Jing
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Yu, Keming
    Brunel University.
    Zeng, Zhaofa
    College of Business Administration, Hunan University.
    Bayesian multivariate monitoring models for process mean vectors based on multistage predictive distributions2011Ingår i: Hunan Daxue Xuebao (Ziran Kexue Ban), ISSN 1674-2974, Vol. 38, nr 3, s. 82-86Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this paper is to utilize sample information in different stages and solve the parameter uncertainty risk in statistical process control. This paper introduces a reference prior distribution for the parameters in quality models, and constructs the warning lines and action lines to monitor the mean vectors change according to the predictive distribution as well as the relationship between the multivariate t distribution and F distribution. When the current stage is under control, the parametric posterior distribution is considered to be their priori distribution in the next stage, in which the sequential Bayesian mean vector control method is established.

  • 2324.
    Zischg, Jonatan
    et al.
    Unit of Environmental Engineering, University of Innsbruck, Austria.
    Goncalves, Mariana L. R.
    Unit of Environmental Engineering, University of Innsbruck, Austria.
    Bacchin, Taneha K.
    Environmental Technology & Design, Department of Urbanism, Faculty of Architecture and the Built Environment, Delft University of Technology, The Netherlands.
    Leonhardt, Günther
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    van Timmeren, Arjan
    Environmental Technology & Design, Department of Urbanism, Faculty of Architecture and the Built Environment, Delft University of Technology, The Netherlands.
    Rauch, Wolfgang
    Unit of Environmental Engineering, University of Innsbruck, Austria.
    Sitzenfrei, Robert
    Unit of Environmental Engineering, University of Innsbruck, Austria.
    Info-Gap robustness pathway method for transitioning of urban drainage systems under deep uncertainties2017Ingår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 76, nr 5, s. 1272-1281Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the urban water cycle, there are different ways of handling stormwater runoff. Traditional systems mainly rely on underground piped, sometimes named ‘gray’ infrastructure. New and so-called ‘green/blue’ ambitions aim for treating and conveying the runoff at the surface. Such concepts are mainly based on ground infiltration and temporal storage. In this work a methodology to create and compare different planning alternatives for stormwater handling on their pathways to a desired system state is presented. Investigations are made to assess the system performance and robustness when facing the deeply uncertain spatial and temporal developments in the future urban fabric, including impacts caused by climate change, urbanization and other disruptive events, like shifts in the network layout and interactions of ‘gray’ and ‘green/blue’ structures. With the Info-Gap robustness pathway method, three planning alternatives are evaluated to identify critical performance levels at different stages over time. This novel methodology is applied to a real case study problem where a city relocation process takes place during the upcoming decades. In this case study it is shown that hybrid systems including green infrastructures are more robust with respect to future uncertainties, compared to traditional network design.

  • 2325.
    Zongqi, Sun
    Luleå tekniska universitet.
    Fracture mechanics and tribology of rock and rock joints1983Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In the first part of the thesis fracture toughness tests of rocks are described. Specimens of Stripa Granite have been tested in three point bending, compact tension and short rod tension. For testing in three point bending two test procedures were used: Specimens without precracking were loaded to complete failure, then approximate fracture toughness, Km , and fracture toughness from secant method, Ksec' were evaluated; Specimens were precracked in a single loading cycle and later loaded and unloaded several times to obtain the apparent fracture tougnesses, K Q Km-data from testing with different notch depth were statistically analyzed in order to determine the relationship between Km and the crack length, a. The main conclusion drawn from the tests are the following. Km-values obtained from specimens without precracking are inevitably lower than KQ-values. This is due to neglect of microcrack growth preceeding crack extension. Acceptable KQ-values can be obtained from the three point bending tests on a common core specimen with 40 mm in diameter and a notch depth ratio of 0.3. Fracture tougness, Ksc' from short rod tests are found to be size independent, and the data is consistent with KQ-values obtained from compact tension tests and three point bending tests. Finally, short rod tests on filled rock joints are presented and the results are shown to be scattered. In the second part of the thesis direct shear tests on joints of granite and slate are presented. A new device to measure vertical and horizontal displacements during shearing is described. A compliance approach is proposed instead of a stiffness approach in evaluating joint behaviour. The joint compliances (normal, shear and off-diagonal) are stress, and or displacement dependent. The normal and off-diagonal compliances obey a power law while the secant shear compliance has a linear relationship with displacement. A study of the complete shear curves shows that not only the shear stress, but also the resultant of the normal stress and shear stress should be considered in evaluation of the shear data. For rough rock surfaces two factors are found to contribute to the shear stress before sliding occurs. The first is the adhesion which occurs at the region of real contact, and the second is a deformation along the fracture surface. A new model for the shear mechanism is proposed. The joint surface parameters of specimens were studied by means of profile measurements. The change of surface parameters is small before and after shear tests. Based on the Hertzian contact theory, new asperity models for closure and shear of rock joints are proposed. The models allow for prediction of normal and shear compliances of rock joints. Good agreement was obtained between experimental data and predicted values according to the theories. For slate the predicted ultimate coefficient of friction is 0.32 - 0.327 and the experimental value is pu = 0.324, and the predicted secant shear compliance is 0.01 m/Gpa, the experimental value is 0.012 m/GPa. Furthermore, the shear model gives a theoretical explanation to some of the phenomenon observed in shear testing.

  • 2326. Åberg, Sture
    Smörjning av hjul och räls med fordonsinstallerat smörjsystem2005Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Nötningen av räl och hjul uppstår i kontakytan mellan räl och hjul. Den är störst i kurvor i kontaktytan mellan räl och hjul. De faktorer som påverkar nötningen är bland annat kurvradie, trafikbelastning i Mbton, STAX, fordonshastigheter, rälsmaterial, fordonstyp, rälsstatus, hjulstatus, antalet axelpassager och friktionen mellan räls - hjul. Normalt nöts rälsens yttersträng i kurvor och motsvarande hjulringar ned kraftigast. För att minska slitage på hjul och räls tillsätts smörjmedel. Man skiljer på två olika principer när det gäller smörjning: Flange wear (smörjmedel appliceras på lokens hjulflänsar) Friction management (smörjmedel appliceras på rälshuvudet Top of Rail) Genom att applicera smörjmedel på rälshuvudena i kurvor minskar slitaget på rälsmaterialet. Detta görs i Sverige med fasta Clicomaticutrustningar som är i drift under vår - höst i norra Sverige och hela Sverige i södra delarna av landet. Ingen smörjning sker vintertid. SJ och Green Cargo har lokinstallerade system för smörjning direkt på rälshuvudet i syfte att minska slitaget på efterföljande vagnshjul. Syftet med denna förstudie är att: Översiktligt beskriva befintliga fordonsmonterade system för smörjning av räls och hjulflänsar Kartlägga behovet i Sverige avseende smörjning från lok. Kortfattat beskriva vilka leverantörers smörjsystem som kan uppnå kraven som finns i Sverige avseende kurvradier, vinterförhållanden och STAX. Prisbilder på loksmörjningssystem Styrning av rälssmörjapparater. Förstudien visar att det är tekniskt, underhållsmässigt och ekonomiskt motiverat att använda smörjapparater som är monterade på lok för att minska sidoslitaget i kurvor och samtidigt ge minskat hjulslitage på lok och vagnar. Som ett led i målsättningen att effektivisera smörjningen av hjul och räls bör en fordonsmonterad smörjutrustning provas. Ett på marknaden etablerat system bör testas med dokumenterad erfarenhet från kallt klimat och tunga transporter typ norra USA eller Kanada. Smörjmedlet bör antingen appliceras som Top of Rail alltså på rälshuvudet eller direkt på lokets flänsar. Smörjutrustning bör installeras dels på det första drivande loket dels på det sista multipelkopplade lokets bakre del för smörjning av efterföljande vagnshjul enligt bild 3. Systemet ska kunna avläsa när kurva uppträder samt kurvans radie, lämpligast via inbyggda sensorer. Olika smörjmedel bör testas för att klara kraven avseende risken för glidning, miljökrav, friktion mellan hjul och räls i kurvor och funktion i kallt klimat samt appliceras utan problem med igenstoppning av munstycken. Följande två leverantörer bör studeras närmare före val av testutrustning: Friction Management Services system TrackGlide - Top of Rail Willy Vogel AG system för hjulflänssmörjning. Eftersom det finns flera intressanta leverantörer för hjulflänssmörjning kan inbjudan gå till ytterligare någon eller några. Utifrån en närmare analys där såväl applikation på lok, kostnad för utrustning, styrning, service, förutsättningarna för körning vintertid, dokumenterade smörjeffekter mm väljs en leverantör ut. Installation av testutrustning bör göras på ett av MTAB:s IORE-lok

  • 2327. Åberg, Sture
    et al.
    Sundgren, Anders
    Förstudie ReRail2005Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Visionen är att Rerail skall bli en framtida ny produkt inom järnvägssektorn som förlänger livslängden, effektiviserar underhållet och ger en lägre livstidskostnad. Design och tillverkning av Rerail ska göras i Norrbotten och levereras till olika kunder runt om i världen. Målet med detta arbete är att: Beskriva och verifiera kraven för att få göra skarpa test i Banverkets spåranläggningar Definiera produkterna och koppling till kundbehov och kundnyttan Definiera krav som underlag för godkännande av Banverket för test Beskriva marknadspotentialen för produkterna Utföra vissa grundläggande tester i laboratoriemiljö Kostnadsanalys för kommande steg enligt projektplanen Analysera konkurrenter och möjliga samarbetspartners Skissa på finansieringsmodeller för det fortsatta arbetet Skapa förutsättningarna för skarpa test hos potentiella kunder Förväntade sluteffekter är att utifrån genomförda mål kunna starta nästa etapp i arbetet med ReRail.

  • 2328. Åhrén, Thomas
    A study of maintenance performance indicators for the Swedish railroad system2005Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The Swedish railway authorities have a long tradition of using performance indicators to follow up their performance. Already in 1915 when they decided to electrify the iron ore line between Kiruna and Riksgränsen, they introduced some indicators to measure and follow up expected benefits of upgrading the transportation system, e.g. total amount and costs per transported iron ore tonnage, employee safety training, and accidents or near-accidents related to the new power source of electricity. Today, one of the requirements on the infrastructure management is to achieve cost-effective maintenance activities and a punctual and cost-effective railroad transportation system. For this, cost-effective maintenance processes are necessary to achieve budget targets, while punctual railroad system is required by different stakeholders. One key issue for Banverket is to verify that undertaken maintenance activities have given expected results, measured in terms of technical, economically, and organizational indicators. The purpose of this thesis is to identify and develop a set of performance indicators that supports the maintenance decision-making process in proportion to punctuality, safety, environmental impact and profitability; i.e. establishing a link and effect model. The main aim is to clarify how different maintenance performance indicators can be used to make optimal decisions in the maintenance process; show and illustrate present status of the infrastructure as well as predict the future condition based upon today's maintenance decisions. The analysis of existing and potential maintenance performance indicators resulted in a useful set of indicators applicable for railway infrastructure assets management, classified into different classes and subgroups appropriate to match a modified link and effect model originally developed for the offshore industry. A link and effect model adjusted to management of railway infrastructure assets is also presented. In order to successfully implement performance indicators it is important to start with the definition of the business goals and overall objectives that later on must be broken down to maintenance objectives. With clear objectives regarding punctuality, safety, environmental impact, and profitability, is it possible to develop and implement indicators, especially performance driver indicators, for a maintenance department or maintenance contract.

  • 2329. Åhrén, Thomas
    Indikatorer: en översikt inom Banverket2004Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Järnvägssystemet är ett komplext system där en oväntad händelse eller störning drabbar många aktörer, exempelvis de uppmärksammade tågförseningar som inträffade under vintern 2001/2002. Därför måste alla störningar i transportprocessen identifieras, studeras, klassificeras, analyseras och om möjligt elimineras genom bättre underhållsinsatser. Beslut om underhållsinsatser bör fattas på rationella grunder och baseras på en genomtänkt underhållsstrategi. Genom forskning och utvecklingsarbetet förväntar man sig att hitta modeller och Key Performance Indicators (KPI) för att styra underhållsverksamheten för att vidmakthålla befintlig infrastruktur och rullande materiel i bra skick och också förlänga dess livslängd. Litteraturundersökningar visar att det saknas entydiga definitioner för indicators, performance indicators och key performance indicators, samtidigt som det även förekommer andra namn på dessa. I exempelvis Sverige används ofta även beteckningar som nyckeltal och index. Det som litteraturen däremot påvisar är att samtliga typer av indikatorer har ett gemensamt syfte, nämligen att skapa underlag för effektiv styrning och uppföljning av enheter, processer, system och/eller organisationer. Indikatorernas inbördes förhållande kan analogt beskrivas som att indicators är de mått och nyckeltal som används på operativ nivå, dvs fabriksgolvet, medan performance indicators är de aggregerade nyckeltal som återfinns på taktisk mellanchefsnivå. Key performance indicators är slutligen de aggregerade nyckeltal, baserade på performance indicators, som återfinns och används på strategisk ledningsnivå. Den kartläggning som genomförts för att hitta befintliga och presumtiva nyckeltal av offentlig karaktär inom Banverket, visar ingen större skillnad i jämförelse med vilka nyckeltal som används inom andra banförvaltande enheter i exempelvis Italien och Australien. Jämförelsen visar att i princip samma typ av data finns att tillgå inom alla tre förvaltningarna.

  • 2330. Åhrén, Thomas
    Kostnadsdrivare - Ofotenbanen2003Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Ofotenbanen är cirka 40 km lång och är en av Norges mest belastade banor. Då Ofotenbanen är geografiskt isolerad ur ett norskt järnvägsperspektiv medför detta att den, trots sin korta längd, fram till dags dato behöver både en egen förvaltnings- och produktionsorganisation. Vid jämförelser med andra bansträckor i Norge leder detta till relativt höga totalkostnader räknat per kilometer bana. En bidragande orsak till detta är att de fasta kostnaderna måste fördelas på relativt få bankilometer. För att klargöra vilka kategorier av komponenter och fel som driver kostnaderna samt hur dessa kan reduceras har Jernbaneverket (JBV) i Narvik kontaktat JvtC (Järnvägstekniskt Centrum) vid Luleå tekniska universitet för att initiera ett utredningsprojekt för att identifiera kostnadsdrivare. Analysen visar att den dominerande kostnadsdrivaren är isolskarvar. Antalet fel för dessa uppgår till 103 st, vilket motsvarar 37% av totala antalet akuta fel. Noteras bör att detta är cirka 2,5 gånger högre än den anläggningsindivid som kommer på andra plats. Kostnaderna för att åtgärda de akuta felen på isolskarvarna motsvarar cirka 24% av totala akuta felavhjälpningskostnaden. Sammanfattningsvis kan konstateras att isolskarvsproblematiken på sikt bör åtgärdas på ett mer permanent sätt. Detta då den direkt påverkar tågtrafiken genom sin omedelbara koppling till säkerhetsmässiga aspekter.

  • 2331.
    Åhrén, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Maintenance performance indicators (MPIs) for railway infrastructure: identification and analysis for improvement2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Infrastrukturförvaltare av järnväg ser idag underhåll som en värdeskapande och integrerad del av hela förvaltningsverksamheten för att uppfylla kundernas krav och förväntningar. En central uppgift för Banverket är att verifiera att genomförda underhållsåtgärder ger önskat resultat ur tekniska, ekonomiska och organisatoriska perspektiv. Ett sätt att mäta detta är att använda underhållsrelaterade indikatorer (MPIs, maintenance performance indicators). Det är därför viktigt att dessa indikatorer förmår koppla och visa effekter av genomförda underhållsaktiviteter, dvs. förmår visa underhållsrelaterade orsak-verkansamband.En studie genomförd på Banverket visar att utav 17 identifierade MPIs så används 10 stycken. Åtta av dessa är identifierade i Banverkets egna dokument medan de två övriga är identifierade genom intervjuer. Två genomförda studier på Banverket och Jernbaneverket visar att det är möjligt att kvantifiera och jämföra MPIs mellan olika länder med hjälp utav benchmarking. Jämförelsen visar att underhållskostnaderna per spårmeter är ungefärligen lika stora på svensk och norsk sida för Malmbanan. En liknande jämförelse av overheadkostnaderna visar att kostnaderna på den norska sidan är ungefär 12 gånger högre per spårmeter räknat. En jämförelse av organisationernas storlek till antalet anställda visar dock att de är ungefärligen jämstora. En teknisk och ekonomisk utvärdering av genomförda rälsslipningskampanjer på sträckan mellan Kiruna och Riksgränsen visar att rälsslipning kan fördröja behovet av utbyte av räl. Den årliga kostnaden för rälsbyte är ett exempel på MPIs som kan användas för uppföljning och benchmarking. Genomförda rälsslipningskampanjer ser inte ut att påverka järnvägssystemet som helhet på något negativt sätt. En viktig fråga för infrastrukturförvaltare av järnväg är att kunna mäta järnvägssystemets effektivitet. En modell för att kunna mäta just detta presenteras i denna avhandling, dvs en så kallad ORIE-modell (overall railway infrastructure effectiveness eller infrastruktureffektivitet för järnväg) Genomförda studier och simulering på bandelsnivå visar på höga och jämförbara ORIE-värden för de olika bandelarna, vilka för övrigt är påtagligt högre än för motsvarande OEE-värden för exempelvis tillverkande industri. Studien påvisar att ORIE-värdena bör beräknas per månad och att de kan användas som MPIs. Resultaten visar på ORIE-värden mellan 89,7 - 100 %. ORIE-värden kan därmed utgöra ett bra beslutsstöd för järnvägens infrastrukturförvaltare. Ett förslag på en länk- och effektmodell för järnvägsinfrastruktur vilken stödjer övergripande mål för verksamheten och som fokuserar på strategiska områden utifrån järnvägens förutsättningar presenteras i denna avhandling. Sammanfattningsvis så har denna studie identifierat ett antal MPIs som används av infrastrukturförvaltare av järnväg. Koncept och modeller såsom LinkEM, ORIE och benchmarking har applicerats på och genererat resultat användbara för infrastrukturförvaltare av järnväg.

  • 2332. Åhrén, Thomas
    et al.
    Espling, Ulla
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Samordnet / Felles drift av järnvägen Kiruna - Narvik2003Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Ofotenbanen är cirka 40 km lång och är en av Norges mest belastade banor. Då Ofotenbanen är geografiskt isolerad ur ett norskt järnvägsperspektiv medför detta att den, trots sin korta längd, fram till dags dato behöver både en egen förvaltnings- och produktionsorganisation. Vid jämförelser med andra bansträckor i Norge leder detta till relativt höga totalkostnader räknat per kilometer bana. En bidragande orsak till detta är att de fasta kostnaderna måste fördelas på relativt få bankilometer. En opartisk undersökning om möjligheterna att samordna eller eventuellt köra gemensam drift på sträckan Kiruna-Riksgränsen har därför utförts av JvtC (Järnvägstekniskt Centrum) på uppdrag av Jernbaneverket (JBV) i Narvik. Analysen visar på likheter i organisationsstruktur (beställar- och utförarorganisation). Beträffande kostnadsbilden har konstaterats att JBV avsätter ca 12% av total budget till förvaltning (overhead-kostnader), medan motsvarande andel på svensk sida uppgår till mindre än 1%. Detta beror på att JBV måste fördela ut dessa kostnader på färre kilometer järnväg än Banverket (BV). Ytterligare bidragande faktor är att samtliga infrastrukturella kostnader på norsk sida belastar/betalas via förvaltarorganisa-tionens budget, vilket inte är fallet för svenskt vidkommande. Exempel på sådana är kostnader för järnvägsrelaterade lokaler som inte används direkt av förvaltningsorganisationen (stationsbyggnader, trafikledningscentralen m.m.). Analys av banrelaterade kostnader visar att de aktiviteter som genomförs i spår genererar likartade kostnader per spårmeter, om än något lägre på norsk sida. På svensk sida finns mer pengar inom budgetramen för preventivt underhåll. För att göra banan mer konkurrenskraftig t.ex genom att kunna pressa vidmakthållandekostnaderna så att det t.ex kan bli möjligt att sänka banavgifter är det viktigt att se över möjligheterna att minska kostnaderna. Eftersom samordning eller gemensam drift med Jernbaneverket i övrigt är starkt begränsat bör möjligheten att samordna verksamheten med den järnväg som ansluter till Ofotenbanan, dvs Malmbanan utredas djupare. Förslag på ett antal arbetsuppgifter möjliga att samordna eller köra i gemensam drift finns uppräknade i kapitel 6.

  • 2333. Åhrén, Thomas
    et al.
    Espling, Ulla
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Benchmarking of maintenance process: two case studies from Banverket, Sweden2005Ingår i: Abstracts of the Eighth International Conference Maintenance & Renewal of Permanent Way; Power & Signalling; Structures & Earthworks: Railway Engineering 2005 / [ed] M.C. Forde, Engineering Technics Press , 2005, s. 17-18Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Maintenance is an ongoing process for any system with the purpose to maintain its given function during its lifetime. Since maintenance is an integrated part of the business process, correctly performed maintenance creates increased business values. For this, the management must strive for continuous improvement of maintenance process. One powerful tool for this purpose is benchmarking, eg comparing own performance with best in the class or other high performance organizations and learning what they do to achieve their high level of performance. To make a successful comparison, common performance indicators must be identified and used. Performance indicators can broadly be classified as lead or lag indicators, where lead indicators are performance drivers and lag indicators are outcome measures. Today, there is a lot of performance indicators in use connected to maintenance, covering for example the area of safety, asset condition and asset reliability, maintenance performance and cost control.This paper presents two case studies, the first one deal with benchmarking the maintenance process and where as the second one compares the use of maintenance performance indicators at the Swedish National Rail Administration (Banverket). We discuss some benchmarking results indicating for example how maintenance strategies, i.e. proactive or reactive, impact the maintenance costs and the ratio of unplanned maintenance. We also emphasize that many of the maintenance performance indicators are used by various organizations abroad and thus provide Banverket an opportunity to benchmark its operation internationally to improve its performance. One of the findings in both case studies is that there are two critical parameters that are missing from the list of indicators, namely traffic volume and infrastructure age. An attempt is also made to analyze the impact of chosen indicators, as well as suggesting future maintenance indicators for future benchmarking.

  • 2334. Åhrén, Thomas
    et al.
    Liyanage, Jayantha P.
    University of Stavanger.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Maintenance performance measurement study at Banverket2006Ingår i: Condition Monitoring and Diagnostic Engineering Management: COMADEM 2006 ; proceedings of the 19th international congress, Luleºa, Sweden, 12 - 15 June 2006 / [ed] Uday Kumar, Luleå: Luleå tekniska universitet, 2006, s. 643-649Konferensbidrag (Refereegranskat)
    Abstract [en]

    Maintenance is an ongoing process for any system with the purpose to maintain given function during its lifetime. Since maintenance today is an integral part of the business process, correctly performed maintenance is known to create increased business value. However, still in various business sectors there is a great potential for continuous improvement of the maintenance process. Such improvements can be done by introducing a performance measurement system in a way that it supports the needs of core business processes, focusing on critical-strategic areas determined by the nature of the business, business concerns, and public requirements and regulations. The outcome from the maintenance process can be measured in terms of return on investments (ROI) and health, safety and environment (HSE); driven by such issues as integrity of the plant, adequate competencies, functional internal processes, and good internal and external relationships. This signifies a top-down approach underlying the importance to link the measures for operations and maintenance (i.e. the operations and maintenance performance measurement system) to overall business or organizational objectives by creating a logical cause-and-effect structure. In turn this also can be used as an effective basis to pinpoint those measures that should become ‘key performance indicators'. The final output from this is a link-and-effect model, showing how the operations and maintenance process contributes to overall business objectives. In the last years, a ROI-based framework for operations and maintenance performance measurement systems has been introduced into such industries where maintenance is performed by the company themselves. On the basis of the above, this paper presents how maintenance ROI can be adapted, measured, and linked to overall objectives in governmental appropriated organizations like the Swedish National Rail Administration (Banverket) where maintenance is outsourced.

  • 2335. Åhrén, Thomas
    et al.
    Parida, Aditya
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Maintenance performance indicators (MPI) for benchmarking the railway infrastructure: a case study2009Ingår i: Benchmarking: An International Journal, ISSN 1463-5771, E-ISSN 1758-4094, Vol. 16, nr 2, s. 247-258Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose - For railway infrastructure, benchmarking is an effective tool that can support the management in their pursuit of continuous improvement by the use of maintenance performance indicators (MPIs). Hence, there is a need to study the MPIs and link them with benchmarking. The purpose of this paper is to present case studies dealing with the application of benchmarking and maintenance performance indicators for the railway infrastructure. Design/methodology/approach - Case studies were conducted at Banverket (the Swedish Rail Administration) and at Jernbaneverket (the Norwegian National Rail Administration), which is responsible for the Norwegian part of the Iron Ore Line between Kiruna in Sweden and Narvik in Norway. The results from the two case studies are compared and analyzed. The benchmarking data for the railway infrastructure are retrieved, classified and analyzed for best practice improvement. Findings - MPIs can successfully use benchmarking as a tool for improvement by learning from within or from other organizations for continuous improvement, which is a rather new phenomenon in the railway industry. Research limitations/implications - Each railway infrastructure is unique due to its geographical locations and constraints, besides the organization, management and other resources. These factors need to be considered while benchmarking the railway infrastructures. Practical implications - The results obtained in these case studies can be used by the railway infrastructure managers for continuous improvements. Moreover, other relevant MPIs required by the railway infrastructure managers can be benchmarked in a similar manner. Originality/value - The paper presents a structured method for continuous improvement of railway infrastructure by using MPIs for benchmarking.

  • 2336. Åhrén, Thomas
    et al.
    Parida, Aditya
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Overall railway infrastructure effectiveness (ORIE): a case study on the Swedish rail network2009Ingår i: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 15, nr 1, s. 17-30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose - The main purpose of this paper is to develop an approach to analyzing the factors influencing the performance of railway infrastructure, to propose an approach to measuring the overall railway infrastructure effectiveness (ORIE), and to test these approaches in a case study to verify their effectiveness. Design/methodology/approach - The methodology adopted here was to develop a concept for measurement of the overall effectiveness of a railway infrastructure similar to that for measurement of the OEE. The concept thus developed was applied on Swedish railway track sections for collecting data and for their ORIE validation, as a case study. Findings - The findings of the ORIE case study show that the model can be used for other sections of the Swedish railways. It can also be applied to other railways with some modifications. Practical implications - ORIE can measure the extent to which the railway infrastructure system manages to deliver its agreed performance to the traffic operators. Infrastructure managers can also use the ORIE as a key performance indicator, which can provide important input for effective decision making. Originality/value - The paper presents a structured way of developing a conceptual ORIE model applied to the railway-sector. This model can be used by other railways with suitable modifications.

  • 2337. Åhrén, Thomas
    et al.
    Waara, Patric
    Larsson-Kråik, Per-Olof
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Technical and economic evaluation of maintenance for rail and wheels on Malmbanan2003Ingår i: Implementation of heavy haul technology for network efficiency: proceedings : International Heavy Haul Conference, Dallas, Texas, May 5-9, 2001, Virginia Beach, Va.: International Heavy Haul Association , 2003, s. 5.81-5.86Konferensbidrag (Refereegranskat)
  • 2338.
    Åström, Jan A.
    et al.
    Centre for Scientific Computing, Esbo.
    Ouchterlony, Finn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Linna, R.P.
    Department of Physics, University of Jyväskylä.
    Timonen, J.
    Department of Physics, University of Jyväskylä.
    Universal dynamic fragmentation in D dimensions2004Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 92, nr 24, s. 245506-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A generic model is introduced for brittle fragmentation in D dimensions, and this model is shown to lead to a fragment-size distribution with two distinct components. In the small fragment-size limit a scale-invariant size distribution results from a crack branching-merging process. At larger sizes the distribution becomes exponential as a result of a Poisson process, which introduces a large-scale cutoff. Numerical simulations are used to demonstrate the validity of the distribution for D = 2. Data from laboratory-scale experiments and large-scale quarry blastings of granitic gneiss confirm its validity for D = 3. In the experiments the nonzero grain size of rock causes deviation from the ideal model distribution in the small-size limit. The size of the cutoff seems to diverge at the minimum energy sufficient for fragmentation to occur, but the scaling exponent is not universal.

  • 2339.
    Öberg, Maria
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Nilsson, Kristina L.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Johansson, Charlotta
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Major transport corridors: the concept of sustainability in EU documents2016Ingår i: Transportation research procedia, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper results are presented from document- and literature studies examining how the concepts of sustainability and sustainable development (economical, ecological and social) are used in the process of developing main transport corridors in the European Union.  Particular focus has been placed on the Scandinavian-Mediterranean (ScanMed) transport corridor, a strategic part of the trans-European network for transports (TEN-T). European Union transport policy documents were studied along with the legislation for TEN-T and documents regarding implementation of the ScanMed corridor.

    The paper highlights that the concept of sustainable development is used in a multifaceted way, sometimes indicating the overarching goal of sustainability, sometimes indicating certain dimensions, and sometimes referring to conducting efforts in a sustainable way. This implies that stakeholders are led to perceive the concept in various ways, influencing how measures are implemented and how the economic, ecological and social dimensions of sustainability are integrated. Reinforcing a holistic perspective of sustainability and sustainable development as integrating economic, ecological and social benefits for a desired development would avoid the perception of sustainability as merely addressing a specific dimension, like environmental concerns. In part this could be strengthened by clearly framing the particular dimensions of sustainability being addressed in different parts of major transport corridor documents, for example; “economic sustainability” or “social sustainability”.

  • 2340.
    Öberg, Maria
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Nilsson, Kristina L.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Johansson, Charlotta
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Major transport corridors: the concept of sustainability in EU documents2017Ingår i: Transportation Research Procedia, ISSN 2324-9935, E-ISSN 2352-1465, Vol. 25, s. 3698-3706Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper results are presented from document- and literature studies examining how the concepts of sustainability and sustainable development (economical, ecological and social) are used in the process of developing main transport corridors in the European Union.  Particular focus has been placed on the Scandinavian-Mediterranean (ScanMed) transport corridor, a strategic part of the trans-European network for transports (TEN-T). European Union transport policy documents were studied along with the legislation for TEN-T and documents regarding implementation of the ScanMed corridor.

    The paper highlights that the concept of sustainable development is used in a multifaceted way, sometimes indicating the overarching goal of sustainability, sometimes indicating certain dimensions, and sometimes referring to conducting efforts in a sustainable way. This implies that stakeholders are led to perceive the concept in various ways, influencing how measures are implemented and how the economic, ecological and social dimensions of sustainability are integrated. Reinforcing a holistic perspective of sustainability and sustainable development as integrating economic, ecological and social benefits for a desired development would avoid the perception of sustainability as merely addressing a specific dimension, like environmental concerns. In part this could be strengthened by clearly framing the particular dimensions of sustainability being addressed in different parts of major transport corridor documents, for example; “economic sustainability” or “social sustainability”.

  • 2341.
    Öhrling, Therese
    et al.
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Arbetsvetenskap.
    Kumar, Rupesh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Abrahamsson, Lena
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Arbetsvetenskap.
    Assessment of the development and implementation of tools in contract cleaning2012Ingår i: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 43, nr 4, s. 687-694Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper illustrates and discusses problems with the implementation and use of ergonomic tools and techniques in the process of cleaning. Cleaning is an occupation with a high risk of developing work-related disorders. One high-strain task where recommended tools and techniques are difficult to apply is cleaning staircases. This study evaluated the muscular activity of cleaners while mopping staircases using two different mop handles and found that an easily adjustable mop handle can decrease a cleaner’s physical load. The results also show that the implementation and contextualization of the mop are of great importance for how a mop is used. A more holistic approach is needed to improve the benefits of good tools and techniques in cleaning work. More research is needed on how workplace organization can be improved to support the implementation of strategies to increase the health of professional cleaners.

  • 2342.
    Öqvist, Jan
    et al.
    Luleå tekniska universitet.
    Rustan, Agne
    Luleå tekniska universitet.
    Sugande ventilation vid eldriven hjullastning under jord1989Rapport (Övrigt vetenskapligt)
  • 2343.
    Öqvist, Rikard
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik. Tyréns AB.
    Measurement and perception of sound insulation from 20 Hz between dwellings2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Population growth and urbanization are projected by the United Nations to add 2,5 billionpeople to the world’s urban population by 2050. We need to construct buildings in anunprecedented scale to meet global housing demand. Sustainable development is critical.Compared to traditional heavy constructions, lightweight wooden constructions are moreenvironmentally friendly and will play a key role in meeting future demands. However, thereare two major problems with lightweight constructions that need to be addressed: 1) Limitedlow frequency sound insulation and 2) Variations in sound insulation.Annoyance from walking sound tend to be higher in lightweight than in heavy constructionseven with the same measured sound insulation. The Swedish research program AkuLiteindicated that the correlation between measured sound insulation and annoyance wassignificantly improved by extending current evaluation methods from 50 Hz down to 20 Hz.Secondly, large variations in sound insulation between nominally identical lightweightconstructions are common, which leads to larger safety margins. By identifying and quantifyingunderlying causes, production costs can be minimized and the performance can be improved.The aim of the thesis is to develop a new evaluation method for impact sound insulation thatbetter correspond to rated annoyance, and to identify and control underlying causes forvariations in sound insulation. The thesis contains six papers.In Paper I and II, sound insulation measurements were carried out in a large number ofnominally identical rooms of two different industrially prefabricated lightweight woodenconstructions. The purpose was to assess and quantify the variations in impact and airbornesound insulation. In Paper I, 30 nominally identical apartments of a volume based system wasevaluated. The apartments on the highest floor achieved significantly better sound insulationdue to the extra weight on lower floors affecting the elastic connections between stories. InPaper II, 18 rooms of a cross-laminated timber system of plate elements were evaluated.Additionally, several potential parameters related to measurement uncertainty wereinvestigated.Paper III deals with measurement uncertainty. An empirical study of reverberation timemeasurements showed that current methods need to be improved, if sound insulationrequirements are to be extended to 20 Hz.Paper IV and V verified that the frequency range 20-50 Hz is important for walking soundannoyance, and that alternative frequency adaptation terms can improve the correlation betweenmeasured impact sound insulation and annoyance ratings. In Paper IV, the methodology was toperform extensive field measurements in apartment buildings of various construction types andto perform questionnaire surveys among the residents. In Paper V, the methodology was toevaluate annoyance based on binaural recordings of walking sound in a two-part listening test.In Paper VI, 70 measurements in a lightweight wooden system were evaluated to quantify thetotal variations in impact and airborne sound insulation from 20 and 50 Hz, respectively. It wasconcluded that the proposed metrics of impact sound insulation were primarily determined bythe impact sound level 20-40 Hz and that the measurement methods must be evaluatedthoroughly to avoid excessive safety margins.

    A new evaluation method for impact sound insulation from 25 Hz, that correspond to the ratedannoyance for both heavy and lightweight constructions is proposed. By using the proposedmethod and attending the specific causes for variations, the lightweight industry will be able todevelop improved multi-story dwellings with higher perceived acoustic quality.

  • 2344.
    Öqwist, Jan
    Luleå tekniska universitet.
    Sensorer: marknadsinventering av sensorer/givare för gas (NO, NO2, CO), radon, temperatur, lufthastighet, differenstryck samt fordonslägeskontroll för användning i underjordsgruvor1991Rapport (Övrigt vetenskapligt)
  • 2345.
    Rustan, Agne (Redaktör)
    Luleå tekniska universitet.
    Försiktig och skonsam sprängning under jord: diskussionsdagar i Luleå 17-18 september 19801980Rapport (Övrigt vetenskapligt)
  • 2346.
    Kumar, Uday (Redaktör)
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Karim, Ramin (Redaktör)
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Parida, Aditya (Redaktör)
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Tretten, Phillip (Redaktör)
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Proceedings of the 3rd international workshop and congress on eMaintenance: June 17-18 Luleå, Sweden : eMaintenance, Trends in technologies & methodologies, challenges, possibilites and applications2014Rapport (Refereegranskat)
    Abstract [en]

    Compilation of papers presented in the technical sessions during the eMaintenance 2014.

  • 2347.
    Swan, Graham (Redaktör)
    Luleå tekniska universitet.
    The stiffness of joints: a workshop report1981Rapport (Övrigt vetenskapligt)
44454647 2301 - 2347 av 2347
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf