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• 1.
Faculty of Computer Science and Information Technology, University of Malaya, Kuala Lumpur.
Faculty of Computer Science and Information Technology, University of Malaya, Kuala Lumpur. Faculty of Computer Science and Information Technology, University of Malaya, Kuala Lumpur. Faculty of Computer Science and Information Technology, University of Malaya, Kuala Lumpur. Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap. Faculty of Computer Science and Information Technology, University of Malaya, Kuala Lumpur. Faculty of Computer Science and Information Technology, University of Malaya, Kuala Lumpur.
Survey on network virtualization using openflow: Taxonomy, opportunities, and open issues2016Ingår i: KSII Transactions on Internet and Information Systems, ISSN 1976-7277, Vol. 10, nr 10, s. 4902-4932Artikel i tidskrift (Refereegranskat)

The popularity of network virtualization has recently regained considerable momentum because of the emergence of OpenFlow technology. It is essentially decouples a data plane from a control plane and promotes hardware programmability. Subsequently, OpenFlow facilitates the implementation of network virtualization. This study aims to provide an overview of different approaches to create a virtual network using OpenFlow technology. The paper also presents the OpenFlow components to compare conventional network architecture with OpenFlow network architecture, particularly in terms of the virtualization. A thematic OpenFlow network virtualization taxonomy is devised to categorize network virtualization approaches. Several testbeds that support OpenFlow network virtualization are discussed with case studies to show the capabilities of OpenFlow virtualization. Moreover, the advantages of popular OpenFlow controllers that are designed to enhance network virtualization is compared and analyzed. Finally, we present key research challenges that mainly focus on security, scalability, reliability, isolation, and monitoring in the OpenFlow virtual environment. Numerous potential directions to tackle the problems related to OpenFlow network virtualization are likewise discussed

• 2.
Geological Engineering Department, Faculty of Mines, Istanbul Technical University. Geology Department, Faculty of Science, Benha University, Benha.
Geological Engineering Department, Faculty of Mines, Istanbul Technical University. Geology Department, Faculty of Science, Benha University, Benaha. Geological Engineering Department, Faculty of Mines, Istanbul Technical University. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
REE geochemical characteristics and satellite-based mapping of hydrothermal alteration in Atud gold deposit, Egypt2018Ingår i: Journal of African Earth Sciences, ISSN 0899-5362, Vol. 145, s. 317-330Artikel i tidskrift (Refereegranskat)

New geochemical data of the hydrothermal alteration zones associated with gold-bearing quartz veins at Atud mine are used for better understanding the ore evolution and exploration vectoring. ASTER and Landsat 8 OLI data are used to elucidate the distribution of gold-associated alteration zones. Three alteration zones are defined; zone 1 (sericite-kaolinite-quartz-pyrite), zone 2 (quartz-sericite-albite-pyrite), and zone 3 (chlorite-carbonate-epidote ± pyrite). Sericite and hydrothermal quartz are confined to the mineralized quartz veins. Fe-OH and OH-bearing minerals are observed along NW- and NE-trending shear zones in the Main Atud mine. The association of gold-bearing quartz veins and sericite alteration is constrained by processing ASTER- and OLI-imagery data. The geochemical data of the ore-enveloping hydrothermally altered rocks are used to assess the behavior of the REEs during the mineralization process. Mild enrichment in LREE and significant enrichment in the HREE are associated with sericite in zones (1) and (2) alterations. Carbonate alteration (zone 3) is enriched in LREE and in immobile HREE. Moreover, LREE and Eu anomalies have negative correlated with the Alteration Index (A.I.) and K2O index (K.I.) in zones 1 and 2, suggesting high mobility of LREE in K-rich hydrothermal fluids. On the other hand, HREE anomalies with increasing MgO index (M.I.) in alteration zone 3 may imply low solubility of these elements in alkaline solutions. Au anomalies linked to sericite/silica alteration is a rather meaningful vector for further exploration in the area.

• 3.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Compactness of embedding between Sobolev type spaces with multiweighted derivatives2009Ingår i: AIHT : Analysis, Inequalities and Homogenization Theory: Midnight sun conference in honor of Lars-Erik Persson, 2009Konferensbidrag (Övrigt vetenskapligt)

We consider a new Sobolev type function space called the space with multiweighted derivatives. As basis for this space serves some differential operators containing weight functions. We establish necessary and sufficient conditions for the boundedness and compactness of the embedding between the spaces with multiweighted derivatives in different selections of weights.

• 4.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Embedding theorems for spaces with multiweighted derivatives2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)

This Licentiate Thesis consists of four chapters, which deal with a new Sobolev type function space called the space with multiweighted derivatives. This space is a generalization of the usual one dimensional Sobolev space. Chapter 1 is an introduction, where, in particular, the importance to study function spaces with weights is discussed and motivated. In Chapter 2 we consider and analyze some results of L. D. Kudryavtsev, where he investigated one dimensional Sobolev spaces. Moreover, in this chapter we present and prove analogous results by B. L. Baidel'dinov for generalized Sobolev spaces. These results are crucially for the proofs of the main results of this Licentiate Thesis. In Chapter 3 we prove some embedding theorems for these new generalized Sobolev spaces. The main results of Kudryavtsev and Baidel'dinov about characterization of the behavior of functions at a singularity take place in weak degeneration of spaces. However, with the help of our new embedding theorems we can extend these results to the case of strong degeneration. In Chapter 4 we prove some new estimates for each function in a Tchebychev system. In order to be able to study also compactness of the embeddings from Chapter 3 such estimates are crucial. I plan to study this question in detail in my further PhD studies.

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• 5.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Some new results concerning boundedness and compactness for embeddings between spaces with multiweighted derivatives2009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)

This Doctoral Thesis consists of five chapters, which deal with a new Sobolev type function space called the space with multiweighted derivatives. This space is a generalization of the usual one dimensional Sobolev space. As basis for this space serves some differential operators containing weight functions.Chapter 1 is an introduction, where, in particular, the importance to study function spaces with weights is discussed and motivated. In Chapter 2 we prove some new estimates for each function in a Tchebychev system. In order to be able to study compactness of the embeddings from Chapter 3 such estimates are crucial.In Chapter 3 we rewrite and present some results of L. D. Kudryavtsev, where he investigated one dimensional Sobolev spaces. Moreover, in this chapter we rewrite and discuss some analogous results by B. L. Baidel'dinov for generalized Sobolev spaces. These results are not available in the Western literatures in this way and they are crucial for the proofs of the main results in Chapter 4. In Chapter 4 we prove some embedding theorems for these new generalized Sobolev spaces. The main results of Kudryavtsev and Baidel'dinov about characterization of the behavior of functions at a singularity take place in weak degeneration of the spaces. However, with the help of our new embedding theorems we can extend theseresults to the case of strong degeneration.The main aim of Chapter 5 is to establish boundedness and compactness of the embedding considered in Chapter 4.In Chapter 4 basically only sufficient conditions for boundedness of this embedding were obtained. In Chapter 5 we obtain necessary and sufficient conditions for boundedness and compactness of this embedding and the main results are proved in a different way.

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• 6. Abdikalikova, Zamira
Compactness of embedding between spaces with multiweighted derivatives: the case 1 ≤ p ≤ q2009Rapport (Övrigt vetenskapligt)
• 7.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Summability of a Tchebysheff system of functions2007Rapport (Övrigt vetenskapligt)
• 8.
L.N. Gumilyov Eurasian National University.
L.N. Gumilyov Eurasian National University. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Boundedness and compactness of the embedding between spaces with multiweighted derivatives when 12011Ingår i: Czechoslovak Mathematical Journal, ISSN 0011-4642, E-ISSN 1572-9141, Vol. 61, nr 1, s. 7-26Artikel i tidskrift (Refereegranskat)

We consider a new Sobolev type function space called the space with multiweighted derivatives W-p(n),(alpha) over bar, where (alpha) over bar = (alpha(0), alpha(1), ......, alpha(n)), alpha(i) is an element of R, i = 0, 1,......,n, and parallel to f parallel to W-p(n),((alpha) over bar) = parallel to D((alpha) over bar)(n)f parallel to(p) + Sigma(n-1) (i=0) vertical bar D((alpha) over bar)(i)f(1)vertical bar, D((alpha) over bar)(0)f(t) = t(alpha 0) f(t), d((alpha) over bar)(i)f(t) = t(alpha i) d/dt D-(alpha) over bar(i-1) f(t), i = 1, 2, ....., n. We establish necessary and sufficient conditions for the boundedness and compactness of the embedding W-p,(alpha) over bar(n) -> W-q,(beta) over bar,(m) when 1 <= q < p < infinity, 0 <= m < n

• 9.
L.N. Gumilyov Eurasian National University.
L.N. Gumilyov Eurasian National University. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Boundedness and compactness of the embedding between spaces with multiweighted derivatives when 1≤ q2009Rapport (Övrigt vetenskapligt)
• 10.
Luleå tekniska universitet, Institutionen för system- och rymdteknik.
Machine Learning assisted system for the resource-constrained atrial fibrillation detection from short single-lead ECG signals2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)

An integration of ICT advances into a conventional healthcare system is spreading extensively nowadays. This trend is known as Electronic health or E-Health. E-Health solutions help to achieve the sustainability goal of increasing the expected lifetime while improving the quality of life by providing a constant healthcare monitoring. Cardiovascular diseases are one of the main killers yearly causing approximately 17.7 million deaths worldwide. The focus of this work is on studying the detection of one of the cardiovascular diseases – Atrial Fibrillation (AF) arrhythmia.  This type of arrhythmia has a severe influence on the heart health conditions and could cause congestive heart failure (CHF), stroke, and even increase the risk of death. Therefore, it is important to detect AF as early as possible. In this thesis we focused on studying various machine learning techniques for AF detection using only short single lead Electrocardiography recordings. A web-based solution was built as a final prototype, which first simulates the reception of a recorded signal, conducts the preprocessing, makes a prediction of the AF presence, and visualizes the result. For the AF detection the relatively high accuracy score was achieved comparable to the one of the state-of-the-art. The work was based on the investigation of the proposed architectures and the usage of the database of signals from the 2017 PhysioNet/CinC Challenge. However, an additional constraint was introduced to the original problem formulation, since the idea of a future deployment on the resource-limited devices places the restrictions on the complexity of the computations being performed for achieving the prediction. Therefore, this constraint was considered during the development phase of the project.

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• 11.
University of Science and Technology Chittagong.
University of Science and Technology Chittagong. University of Chittagong, Bangladesh. Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap. University of Science and Technology Chittagong.
An Interoperable IP based WSN for Smart Irrigation Systems2017Konferensbidrag (Refereegranskat)

Wireless Sensor Networks (WSN) have been highly developed which can be used in agriculture to enable optimal irrigation scheduling. Since there is an absence of widely used available methods to support effective agriculture practice in different weather conditions, WSN technology can be used to optimise irrigation in the crop fields. This paper presents architecture of an irrigation system by incorporating interoperable IP based WSN, which uses the protocol stacks and standard of the Internet of Things paradigm. The performance of fundamental issues of this network is emulated in Tmote Sky for 6LoWPAN over IEEE 802.15.4 radio link using the Contiki OS and the Cooja simulator. The simulated results of the performance of the WSN architecture presents the Round Trip Time (RTT) as well as the packet loss of different packet size. In addition, the average power consumption and the radio duty cycle of the sensors are studied. This will facilitate the deployment of a scalable and interoperable multi hop WSN, positioning of border router and to manage power consumption of the sensors.

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• 12.
University of Science and Technology, Chittagong.
University of Science and Technology, Chittagong. University of Science and Technology, Chittagong. University of Science and Technology, Chittagong. University of Chittagong, Bangladesh. Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
Selection of Energy Efficient Routing Protocol for Irrigation Enabled by Wireless Sensor Networks2017Ingår i: Proceedings of 2017 IEEE 42nd Conference on Local Computer Networks Workshops, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 75-81Konferensbidrag (Refereegranskat)

Wireless Sensor Networks (WSNs) are playing remarkable contribution in real time decision making by actuating the surroundings of environment. As a consequence, the contemporary agriculture is now using WSNs technology for better crop production, such as irrigation scheduling based on moisture level data sensed by the sensors. Since WSNs are deployed in constraints environments, the life time of sensors is very crucial for normal operation of the networks. In this regard routing protocol is a prime factor for the prolonged life time of sensors. This research focuses the performances analysis of some clustering based routing protocols to select the best routing protocol. Four algorithms are considered, namely Low Energy Adaptive Clustering Hierarchy (LEACH), Threshold Sensitive Energy Efficient sensor Network (TEEN), Stable Election Protocol (SEP) and Energy Aware Multi Hop Multi Path (EAMMH). The simulation is carried out in Matlab framework by using the mathematical models of those algortihms in heterogeneous environment. The performance metrics which are considered are stability period, network lifetime, number of dead nodes per round, number of cluster heads (CH) per round, throughput and average residual energy of node. The experimental results illustrate that TEEN provides greater stable region and lifetime than the others while SEP ensures more througput.

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• 13.
University of Science and Technology, Chittagong.
University of Science and Technology Chittagong. University of Science & Technology Chittagong. University of Science and Technology Chittagong. University of Chittagong, Bangladesh. Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
Performance Analysis of Anomaly Based Network Intrusion Detection Systems2018Ingår i: Proveedings of the 43nd IEEE Conference on Local Computer Networks Workshops (LCN Workshops), Piscataway, NJ: IEEE Computer Society, 2018, s. 1-7Konferensbidrag (Refereegranskat)

Because of the increased popularity and fast expansion of the Internet as well as Internet of things, networks are growing rapidly in every corner of the society. As a result, huge amount of data is travelling across the computer networks that lead to the vulnerability of data integrity, confidentiality and reliability. So, network security is a burning issue to keep the integrity of systems and data. The traditional security guards such as firewalls with access control lists are not anymore enough to secure systems. To address the drawbacks of traditional Intrusion Detection Systems (IDSs), artificial intelligence and machine learning based models open up new opportunity to classify abnormal traffic as anomaly with a self-learning capability. Many supervised learning models have been adopted to detect anomaly from networks traffic. In quest to select a good learning model in terms of precision, recall, area under receiver operating curve, accuracy, F-score and model built time, this paper illustrates the performance comparison between Naïve Bayes, Multilayer Perceptron, J48, Naïve Bayes Tree, and Random Forest classification models. These models are trained and tested on three subsets of features derived from the original benchmark network intrusion detection dataset, NSL-KDD. The three subsets are derived by applying different attributes evaluator’s algorithms. The simulation is carried out by using the WEKA data mining tool.

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• 14.
University of Texas, Physics Department.
University of Texas, Physics Department. Department of Chemistry, University of Gothenburg.
Collision-induced absorption at wavelengths near 5 μm by dense hydrogen gas2009Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 131, nr 18, artikel-id 181102Artikel i tidskrift (Refereegranskat)

Based on a recent ab initiointeraction-induced dipole surface of collisionally interacting molecular hydrogen pairs H2–H2, we compute the binary absorption coefficients at wavelengths near 5 μm at temperatures of 77.5 and 297 K for comparison with existing laboratory measurements. We observe satisfactory agreement of the measurements with our calculations, thereby concluding an earlier study [Gustafsson et al., J. Chem. Phys.119, 12264 (2003)], which was based on an ab initiointeraction-induced dipole surface that was inadequate for the 5 μm band.

• 15.
University of Texas, Physics Department.
University of Texas, Physics Department. Physics Department, Beijing Institute of Technology, China, University of Texas, Physics Department. Department of Chemistry, University of Gothenburg. Department of Chemistry, Michigan State University. Department of Chemistry, Michigan State University, East Lansing, Department of Chemistry, Michigan State University.
Collision-induced absorption by supermolecular complexes from a new potential energy and induced dipole surface, suited for calculations up to thousands of kelvin2010Ingår i: 20th International Conference on Spectral Line Shapes: St. John's, Newfoundland, Canada, 6 - 11 June 2010 ; [20th ICSLS] / [ed] John K.C. Lewis; Adriana Predoi-Cross, Melville, NY: American Institute of Physics (AIP), 2010, s. 251-257Konferensbidrag (Refereegranskat)

Absorption by pairs of H2 molecules is an important opacity source in the atmospheres of the outer planets, and thus of special astronomical interest. The emission spectra of cool white dwarf stars differ significantly from the expected blackbody spectra, amongst other reasons due to absorption by H2-H2, H2-He, and H2-H collisional complexes in the stellar atmospheres. To model the radiative processes in these atmospheres, which have temperatures of several thousand kelvin, one needs accurate knowledge of the induced dipole (ID) and potential energy surfaces (PES) of such collisional complexes. These come from quantum-chemical calculations with the H2 bonds stretched or compressed far from equilibrium. Laboratory measurements of collision-induced (CI) absorption exist only at much lower temperature. For H2 pairs at room temperature, the calculated spectra of the rototranslational band, the fundamental band, and the first overtone match the experimental data very well. In addition, with the newly obtained IDS it became possible to reproduce the measurements in the far blue wing of the rototranslational spectrum of H2 at 77.5 K, as well as at 300 K. Similarly good agreement between theory and measurement is seen in the fundamental band of molecular deuterium at room temperature. Furthermore, we also show the calculated absorption spectra of H2-He at 600 K and of H2-H2 at 2,000 K, for which there are no experimental data for comparison

• 16.
Luleå tekniska universitet. Sweco Rail AB.
Sweco Rail handbok för avbrottsfri kraftförsörjning till Trafikverkets linjebundna signalanläggningar2018Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
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• 17.
University of Haifa.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. University of Tromsø ; The Arctic University of Norway, Narvik.
Fejer and Hermite–Hadamard Type Inequalitiesfor N-Quasiconvex Functions2017Ingår i: Mathematical notes of the Academy of Sciences of the USSR, ISSN 0001-4346, E-ISSN 1573-8876, Vol. 102, nr 5-6, s. 599-609Artikel i tidskrift (Refereegranskat)

Abstract—Some new extensions and refinements of Hermite–Hadamard and Fejer type inequali-ties for functions which are N-quasiconvex are derived and discussed.

• 18.
Department of Mathematics, University of Haifa, Haifa, Israel.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. UIT The Arctic University of Norway, Narvik, Norway.
Extensions and Refinements of Fejer and Hermite–Hadamard Type Inequalities2018Ingår i: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 21, nr 3, s. 759-772Artikel i tidskrift (Refereegranskat)

In this paper extensions and refinements of Hermite-Hadamard and Fejer type inequalities are derived including monotonicity of some functions related to the Fejer inequality and extensions for functions, which are 1-quasiconvex and for function with bounded second derivative. We deal also with Fejer inequalities in cases that p, the weight function in Fejer inequality, is not symmetric but monotone on [a, b] .

• 19.
Department of Mathematics, University of Haifa.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Some New Refined Hardy Type Inequalities with Breaking Points p = 2 or p = 32014Ingår i: Concrete Operators, Spectral Theory, Operators in Harmonic Analysis and Approximation: 22nd International Workshop in Operator Theory and its Applications, Sevilla, July 2011 / [ed] Manuel Cepedello Boiso; Håkan Hedenmalm; Marinus A. Kaashoek; Alfonso Montes Rodríguez; Sergei Treil, Basel: Encyclopedia of Global Archaeology/Springer Verlag, 2014, s. 1-10Konferensbidrag (Refereegranskat)

For usual Hardy type inequalities the natural “breaking point” (the parameter value where the inequality reverses) is p = 1. Recently, J. Oguntuase and L.-E. Persson proved a refined Hardy type inequality with breaking point at p = 2. In this paper we show that this refinement is not unique and can be replaced by another refined Hardy type inequality with breaking point at p = 2. Moreover, a new refined Hardy type inequality with breaking point at p = 3 is obtained. One key idea is to prove some new Jensen type inequalities related to convex or superquadratic funcions, which are also of independent interest

• 20.
Department of Mathematics, University of Haifa.
Faculty of Textile Technology, University of Zagreb. Faculty of Textile Technology, University of Zagreb. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Some new refined Hardy type inequalities with general kernels and measures2010Ingår i: Aequationes Mathematicae, ISSN 0001-9054, E-ISSN 1420-8903, Vol. 79, nr 1-2, s. 157-172Artikel i tidskrift (Refereegranskat)

We state and prove some new refined Hardy type inequalities using the notation of superquadratic and subquadratic functions with an integral operator Ak defined by, where k: Ω1 × Ω2 is a general nonnegative kernel, (Ω1, μ1) and (Ω2, μ2) are measure spaces and,. The relations to other results of this type are discussed and, in particular, some new integral identities of independent interest are obtained.

• 21.
Department of Mathematics, University of Haifa.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Inequalities for averages of quasiconvex and superquadratic functions2016Ingår i: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 19, nr 2, s. 535-550Artikel i tidskrift (Refereegranskat)

For n ε ℤ+ we consider the difference Bn-1 (f)-Bn(f):= 1/an n-1/ηi=0 f(ai/an-1)-1/an+1 nηi=0f(ai/an) where the sequences{ai} and {ai-ai-1} are increasing. Some lower bounds are derived when f is 1-quasiconvex and when f is a closely related superquadratic function. In particular, by using some fairly new results concerning the so called "Jensen gap", these bounds can be compared. Some applications and related results about An-1 (f)-An(f):= 1/an n-1/ηi=0 f(ai/an-1)-1/an+1 nηi=0f(ai/an) are also included.

• 22.
Department of Mathematics, University of Haifa.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Some new estimates of the ‘Jensen gap’2016Ingår i: Journal of inequalities and applications (Print), ISSN 1025-5834, E-ISSN 1029-242X, Vol. 2016, artikel-id 39Artikel i tidskrift (Refereegranskat)

Let (μ,Ω) be a probability measure space. We consider the so-called ‘Jensen gap’ J(φ,μ,f)=∫ Ω φ(f(s))dμ(s)−φ(∫ Ω f(s)dμ(s)) for some classes of functions φ. Several new estimates and equalities are derived and compared with other results of this type. Especially the case when φ has a Taylor expansion is treated and the corresponding discrete results are pointed out.

• 23.
University of Haifa.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Some new scales of refined Hardy type inequalities via functions related to superquadracity2013Ingår i: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 16, nr 3, s. 679-695Artikel i tidskrift (Refereegranskat)

For the Hardy type inequalities the "breaking point" (=the point where the inequality reverses) is p = 1. Recently, J. Oguntoase and L. E. Persson proved a refined Hardy type inequality with a breaking point at p = 2. In this paper we prove a new scale of refined Hardy type inequality which can have a breaking point at any p ≥ 2. The technique is to first make some further investigations for superquadratic and superterzatic functions of independent interest, among which, a new Jensen type inequality is proved

• 24.
University of Haifa, Department of Mathematics.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. University of Zagreb. University of Zagreb.
General inequalities via isotonic subadditive functionals2007Ingår i: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 10, nr 1, s. 15-28Artikel i tidskrift (Refereegranskat)

In this manuscript a number of general inequalities for isotonic subadditive functionals on a set of positive mappings are proved and applied. In particular, it is pointed out that these inequalities both unify and generalize some general forms of the Holder, Popoviciu, Minkowski, Bellman and Power mean inequalities. Also some refinements of some of these results are proved.

• 25.
University of Haifa.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
On some new developments of Hardy-type inequalities2012Ingår i: 9th International Conference on Mathematical Problems in Engineering, Aerospace and Sciences: ICNPAA 2012 / [ed] Seenith Sivasundaram, Melville, NY: American Institute of Physics (AIP), 2012, s. 739-746Konferensbidrag (Refereegranskat)

In this paper we present and discuss some new developments of Hardy-type inequalities, namely to derive (a) Hardy-type inequalities via a convexity approach, (b) refined scales of Hardy-type inequalities with other “breaking points” than p = 1 via superquadratic and superterzatic functions, (c) scales of conditions to characterize modern forms of weighted Hardy-type inequalities.

• 26.
Department of Mathematics, University of Haifa.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
On γ-quasiconvexity, superquadracity and two-sided reversed Jensen type inequalities2015Ingår i: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 18, nr 2, s. 615-627Artikel i tidskrift (Refereegranskat)

In this paper we deal with γ -quasiconvex functions when −1γ 0, to derive sometwo-sided Jensen type inequalities. We also discuss some Jensen-Steffensen type inequalitiesfor 1-quasiconvex functions. We compare Jensen type inequalities for 1-quasiconvex functionswith Jensen type inequalities for superquadratic functions and we extend the result obtained forγ -quasiconvex functions to more general classes of functions.

• 27.
Department of Mathematics, University of Haifa.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Some new scales of refined Jensen and Hardy type inequalities2014Ingår i: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 17, nr 3, s. 1105-1114Artikel i tidskrift (Refereegranskat)

Some scales of refined Jensen and Hardy type inequalities are derived and discussed. The key object in our technique is ? -quasiconvex functions K(x) defined by K(x)x-? =? (x) , where Φ is convex on [0,b) , 0 < b > ∞ and γ > 0.

• 28.
Department of Engineering Technology, Miami University, Hamilton, OH.
Department of Engineering Technology, Miami University, Hamilton, OH. Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
Distributed home automation system based on IEC61499 function blocks and wireless sensor networks2017Ingår i: Proceedings of the IEEE International Conference on Industrial Technology, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 1354-1359, artikel-id 7915561Konferensbidrag (Refereegranskat)

In this paper, a distributed home automation system will be demonstrated. Traditional systems are based on a central controller where all the decisions are made. The proposed control architecture is a solution to overcome the problems such as the lack of flexibility and re-configurability that most of the conventional systems have. This has been achieved by employing a method based on the new IEC 61499 function block standard, which is proposed for distributed control systems. This paper also proposes a wireless sensor network as the system infrastructure in addition to the function blocks in order to implement the Internet-of-Things technology into the area of home automation as a solution for distributed monitoring and control. The proposed system has been implemented in both Cyber (nxtControl) and Physical (Contiki-OS) level to show the applicability of the solution

• 29.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
Inequalities for some classes of Hardy type operators and compactness in weighted Lebesgue spaces2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)

This PhD thesis is devoted to investigate weighted differential Hardy inequalities and Hardy-type inequalities with the kernel when the kernel has an integrable singularity, and also the additivity of the estimate of a Hardy type operator with a kernel.The thesis consists of seven papers (Papers 1, 2, 3, 4, 5, 6, 7) and an introduction where a review on the subject of the thesis is given. In Paper 1 weighted differential Hardy type inequalities are investigated on the set of compactly supported smooth functions, where necessary and sufficient conditions on the weight functions are established for which this inequality and two-sided estimates for the best constant hold. In Papers 2, 3, 4 a more general class of $\alpha$-order fractional integrationoperators are considered including the well-known classical Weyl, Riemann-Liouville, Erdelyi-Kober and Hadamard operators. Here 0 < $\alpha$ < 1. In Papers 2 and 3 the boundedness and compactness of two classes of such operators are investigated namely of Weyl and Riemann-Liouville type, respectively, in weighted Lebesgue spaces for 1 < p ≤ q < 1 and 0 < q < p < ∞. As applications some new results for the fractional integration operators of Weyl, Riemann-Liouville, Erdelyi-Kober and Hadamard are given and discussed.In Paper 4 the Riemann-Liouville type operator with variable upper limit is considered. The main results are proved by using a localization method equipped with the upper limit function and the kernel of the operator. In Papers 5 and 6 the Hardy operator with kernel is considered, where the kernel has a logarithmic singularity. The criteria of the boundedness and compactness of the operator in weighted Lebesgue spaces are given for 1 < p ≤ q < ∞ and 0 < q < p < ∞, respectively. In Paper 7 we investigated the weighted additive estimates for integral operators K+ and K¯ defined by

K+ ƒ(x) := ∫ k(x,s) ƒ(s)ds,  K¯ ƒ(x) := ∫ k(x,s)ƒ(s)ds.

It is assumed that the kernel k of the operators K+and K- belongs to the general Oinarov class. We derived the criteria for the validity of these addittive estimates when 1 ≤ p≤ q < ∞

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• 30.
Department of Mechanics and Mathematics, L.N. Gumilyov Eurasian National University, Astana .
Department of Mechanics and Mathematics, L.N. Gumilyov Eurasian National University, Astana. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Boundedness and compactness of a class of Hardy type operators2016Ingår i: Journal of inequalities and applications (Print), ISSN 1025-5834, E-ISSN 1029-242X, nr 1, artikel-id 324Artikel i tidskrift (Refereegranskat)

We establish characterizations of both boundedness and of compactness of a general class of fractional integral operators involving the Riemann-Liouville, Hadamard, and Erdelyi-Kober operators. In particular, these results imply new results in the theory of Hardy type inequalities. As applications both new and well-known results are pointed out.

• 31.
Department of Mechanics and Mathematics, L.N. Gumilyov Eurasian National University, Astana, Kazakhstan .
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. UiT, Tromso, Norway. RUDN University, Moscow, Russia.
Hardy type inequalities and compactness of a class of integral operators with logarithmic singularities2018Ingår i: Mathematical Inequalities & Applications, ISSN 1331-4343, E-ISSN 1848-9966, Vol. 21, nr 1, s. 201-215, artikel-id 21-16Artikel i tidskrift (Refereegranskat)

We establish criteria for both boundedness and compactness for some classes of integraloperators with logarithmic singularities in weighted Lebesgue spaces for cases 1 < p 6 q <¥ and 1 < q < p < ¥. As corollaries some corresponding new Hardy inequalities are pointedout.1

• 32.
L. N.Gumilev Eurasian National University, Khazakstan.
L. N.Gumilev Eurasian National University, Khazakstan. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Additive weighted Lp estimates of some classes of integral operators involving generalized Oinarov Kernels2017Ingår i: Journal of Mathematical Inequalities, ISSN 1846-579X, E-ISSN 1848-9575, Vol. 11, nr 3, s. 683-694Artikel i tidskrift (Refereegranskat)

Abstract. Inequalities of the formkuK f kq 6C(kr f kp +kvH f kp) , f > 0,are considered, where K is an integral operator of Volterra type and H is the Hardy operator.Under some assumptions on the kernel K we give necessary and sufficient conditions for suchan inequality to hold.1

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• 33.
Cornell University, Ithaca.
Cornell University, Ithaca. Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
Characterizing user access to videos on the World Wide Web1999Ingår i: Multimedia computing and networking 2000 / [ed] Klara Nahrstedt, Bellingham, Wash: SPIE - International Society for Optical Engineering, 1999, s. 130-141Konferensbidrag (Refereegranskat)

Despite evidence of rising popularity of video on the web (or VOW), little is known about how users access video. However, such a characterization can greatly benefit the design of multimedia systems such as web video proxies and VOW servers. Hence, this paper presents an analysis of trace data obtained from an ongoing VOW experiment in Lulea University of Technology, Sweden. This experiment is unique as video material is distributed over a high bandwidth network allowing users to make access decisions without the network being a major factor. Our analysis revealed a number of interesting discoveries regarding user VOW access. For example, accesses display high temporal locality: several requests for the same video title often occur within a short time span. Accesses also exhibited spatial locality of reference whereby a small number of machines accounted for a large number of overall requests. Another finding was a browsing pattern where users preview the initial portion of a video to find out if they are interested. If they like it, they continue watching, otherwise they halt it. This pattern suggests that caching the first several minutes of video data should prove effective. Lastly, the analysis shows that, contrary to previous studies, ranking of video titles by popularity did not fit a Zipfian distribution.

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• 34.
COSMOSE Research Group, Department of Computer Science, COMSATS University Islamabad, Islamabad, Pakistan.
COSMOSE Research Group, Department of Computer Science, COMSATS University Islamabad, Islamabad, Pakistan. Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
Variations in power of opinion leaders in online communication networks2018Ingår i: Royal Society Open Science, E-ISSN 2054-5703, Vol. 5, nr 10, artikel-id 180642Artikel i tidskrift (Refereegranskat)

Online social media has completely transformed how we communicate with each other. While online discussion platforms are available in the form of applications and websites, an emergent outcome of this transformation is the phenomenon of ‘opinion leaders’. A number of previous studies have been presented to identify opinion leaders in online discussion networks. In particular, Feng (2016 Comput. Hum. Behav. 54, 43–53. (doi:10.1016/j.chb.2015.07.052)) has identified five different types of central users besides outlining their communication patterns in an online communication network. However, the presented work focuses on a limited time span. The question remains as to whether similar communication patterns exist that will stand the test of time over longer periods. Here, we present a critical analysis of the Feng framework both for short-term as well as for longer periods. Additionally, for validation, we take another case study presented by Udanor et al. (2016 Program 50, 481–507. (doi:10.1108/PROG-02-2016-0011)) to further understand these dynamics. Results indicate that not all Feng-based central users may be identifiable in the longer term. Conversation starter and influencers were noted as opinion leaders in the network. These users play an important role as information sources in long-term discussions. Whereas network builder and active engager help in connecting otherwise sparse communities. Furthermore, we discuss the changing positions of opinion leaders and their power to keep isolates interested in an online discussion network.

• 35. Adeleke, E.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
On a new class of Hardy-type inequalities2012Ingår i: Journal of inequalities and applications (Print), ISSN 1025-5834, E-ISSN 1029-242X, Vol. 2012, nr 259Artikel i tidskrift (Refereegranskat)

In this paper, we generalize a Hardy-type inequality to the class of arbitrary non-negative functions bounded from below and above with a convex function multiplied with positive real constants. This enables us to obtain new generalizations of the classical integral Hardy's, Hardy-Hilbert's, Hardy-Littlewood-P\'{o}lya's and P\'{o}lya-Knopp's inequalities as well as of Godunova's and of some recently obtained inequalities in multidimensional settings. Finally, we apply a similar idea to functions bounded from below and above with a superquadratic function.

• 36.
Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB. Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
Conversational Systems in Machine Learning from the Point of View of the Philosophy of Science—Using Alime Chat and Related Studies2019Ingår i: Philosophies, ISSN 2409-9287, Vol. 4, nr 3, artikel-id 41Artikel i tidskrift (Refereegranskat)

This essay discusses current research efforts in conversational systems from the philosophy of science point of view and evaluates some conversational systems research activities from the standpoint of naturalism philosophical theory. Conversational systems or chatbots have advanced over the decades and now have become mainstream applications. They are software that users can communicate with, using natural language. Particular attention is given to the Alime Chat conversational system, already in industrial use, and the related research. The competitive nature of systems in production is a result of different researchers and developers trying to produce new conversational systems that can outperform previous or state-of-the-art systems. Different factors affect the quality of the conversational systems produced, and how one system is assessed as being better than another is a function of objectivity and of the relevant experimental results. This essay examines the research practices from, among others, Longino’s view on objectivity and Popper’s stand on falsification. Furthermore, the need for qualitative and large datasets is emphasized. This is in addition to the importance of the peer-review process in scientific publishing, as a means of developing, validating, or rejecting theories, claims, or methodologies in the research community. In conclusion, open data and open scientific discussion fora should become more prominent over the mere publication-focused trend.

• 37.
Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
Inner For-Loop for Speeding Up Blockchain Mining2020Ingår i: Open Computer Science, ISSN 2299-1093, Vol. 10, nr 1, s. 42-47Artikel i tidskrift (Refereegranskat)

In this paper, the authors propose to increase the efficiency of blockchain mining by using a population-based approach. Blockchain relies on solving difficult mathematical problems as proof-of-work within a network before blocks are added to the chain. Brute force approach, advocated by some as the fastest algorithm for solving partial hash collisions and implemented in Bitcoin blockchain, implies exhaustive, sequential search. It involves incrementing the nonce (number) of the header by one, then taking a double SHA-256 hash at each instance and comparing it with a target value to ascertain if lower than that target. It excessively consumes both time and power. In this paper, the authors, therefore, suggest using an inner for-loop for the population-based approach. Comparison shows that it’s a slightly faster approach than brute force, with an average speed advantage of about 1.67% or 3,420 iterations per second and 73% of the time performing better. Also, we observed that the more the total particles deployed, the better the performance until a pivotal point. Furthermore, a recommendation on taming the excessive use of power by networks, like Bitcoin’s, by using penalty by consensus is suggested.

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• 38. Adey, J
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Erratum: Degradation of Boron-Doped Czochralski-Grown Silicon Solar Cells [Phys. Rev. Lett., 93, 055504 (2004)]2004Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 93, nr 16, s. 169904-Artikel i tidskrift (Övrigt vetenskapligt)
• 39.
School of Physics, University of Exeter.
School of Physics, University of Exeter. School of Physics, University of Exeter. School of Natural Science, University of Newcastle upon Tyne. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Degradation of boron-doped Czochralski-grown silicon solar cells2004Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 93, nr 5, s. 055504-1Artikel i tidskrift (Refereegranskat)

The formation mechanism and properties of the boron-oxygen center responsible for the degradation of Czochralski-grown Si(B) solar cells during operation is investigated using density functional calculations. We find that boron traps an oxygen dimer to form a bistable defect with a donor level in the upper half of the band gap. The activation energy for its dissociation is found to be 1.2 eV. The formation of the defect from mobile oxygen dimers, which are shown to migrate by a Bourgoin mechanism under minority carrier injection, has a calculated activation energy of 0.3 eV. These energies and the dependence of the generation rate of the recombination center on boron concentration are in good agreement with observations.

• 40.
School of Physics, University of Exeter.
School of Physics, University of Exeter. School of Natural Science, University of Newcastle upon Tyne. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
Theory of boron-vacancy complexes in silicon2005Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 71, nr 16, s. 165211-Artikel i tidskrift (Refereegranskat)

The substitutional boron-vacancy BsV complex in silicon is investigated using the local density functional theory. These theoretical results give an explanation of the experimentally reported, well established metastability of the boron-related defect observed in p-type silicon irradiated at low temperature and of the two hole transitions that are observed to be associated with one of the configurations of the metastable defect. BsV is found to have several stable configurations, depending on charge state. In the positive charge state the second nearest neighbor configuration with C1 symmetry is almost degenerate with the second nearest neighbor configuration that has C1h symmetry since the bond reconstruction is weakened by the removal of electrons from the center. A third nearest neighbor configuration of BsV has the lowest energy in the negative charge state. An assignment of the three energy levels associated with BsV is made. The experimentally observed Ev+0.31 eV and Ev+0.37 eV levels are related to the donor levels of second nearest neighbor BsV with C1 and C1h symmetry respectively. The observed Ev+0.11 eV level is assigned to the vertical donor level of the third nearest neighbor configuration. The boron-divacancy complex BsV2 is also studied and is found to be stable with a binding energy between V2 and Bs of around 0.2 eV. Its energy levels lie close to those of the V2. However, the defect is likely to be an important defect only in heavily doped material.

• 41.
Department of Chemistry, University of Sussex, Falmer, Brighton.
Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Electrical, Electronic and Computer Engineering, University of Newcastle upon Tyne. Department of Chemistry, University of Sussex, Falmer, Brighton.
DFT study of the chemistry of sulfur in graphite, including interactions with defects, edges and folds2013Ingår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 62, s. 256-262Artikel i tidskrift (Refereegranskat)

Sulfur has several roles, desirable and undesirable, in graphitization. We perform density functional theory calculations within the local density approximation to define the structures and energetics of sulphur in graphite, including its interactions with point defects and edges, in order to understand its role in the later stages of graphitization. We find sulphur does not cross-link layers, except where there are defects. It reacts very strongly with vacancies in neighbouring layers to form a six coordinate split vacancy structure, analogous to that found in diamond. It is also highly stable at basal edge sites, where, as might be expected, the size and valency of sulfur can be easily accommodated. This suggests a role for sulphur in stabilizing graphene edges, and following from this, we show that sulfur dimers can open, i.e. unzip, folds in graphite rapidly and exothermically.

• 42.
Joint Institute for Nuclear Research Joliot-Curie 6.
Institute of High Energy Physics - Moscow Region. INFN Sezione di Perugia. INFN Sezione di Perugia. Institute of High Energy Physics - Moscow Region. INFN Sezione di Ferrara. INFN Sezione di Perugia. INFN Sezione di Perugia. Università dell'Insubria. INFN Sezione di Perugia. INFN Laboratori Nazionali di Legnaro. INFN Sezione di Roma. Institute of High Energy Physics - Moscow Region. INFN Sezione di Ferrara. INFN Laboratori Nazionali di Legnaro. Petersburg Nuclear Physics Institute. INFN Laboratori Nazionali di Legnaro. INFN Sezione di Ferrara. Università dell'Insubria. Petersburg Nuclear Physics Institute. INFN Sezione di Ferrara. Università dell'Insubria. INFN Sezione di Perugia. Petersburg Nuclear Physics Institute. Petersburg Nuclear Physics Institute. INFN Laboratori Nazionali di Legnaro. INFN Sezione di Perugia.
Experimental apparatus to study crystal channeling in an external SPS beamline2007Ingår i: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 6634Artikel i tidskrift (Refereegranskat)

For the new generation of high intensity hadronic machines as, for instance, LHC, halo collimation is a necessary issue for the accelerator to operate at the highest possible luminosity and to prevent the damage of superconductor magnets.1 We propose an experiment aimed to systematic study of the channeling phenomenology and of the newly observed "volume reflection" effect. This experiment will be performed for an external SPS beamline and will make use of a primary proton beam with 400 GeV/c momentum and very small (∼ 3 μrad) divergence. The advantage of a proposed experiment is precise tracking of particles that interacted with a crystal, so that to determine the single-pass efficiency for all the processes involved. For this purpose, a telescope equipped with high-resolution silicon microstrip detectors will be used. New generation silicon crystals and an extra-precise goniometer are mandatory issues. Main goal of the experiment is to get the precise information on channeling of relativistic particles and, ultimately, on the feasibility of such technique for halo collimation at LHC. In this contribution we review the status of the setting-up of experimental apparatus and its future development in sight of the planned run in September 2006.

• 43.
Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia.
Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Faculty of Mechanical Engineering, Universiti Teknologi Malaysia. Department of Environmental Management and Policy, BUITEMS Quetta, Pakistan.
Nanoparticles based drilling muds a solution to drill elevated temperature wells: a review2017Ingår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 76, s. 1301-1313Artikel i tidskrift (Refereegranskat)

Demand of the oil and gas energy is increasing very drastically. Conventional hydrocarbon reservoirs contain below the sealing cap rock (shale) and easily move towards wellbore are at the depletion stage. Therefore, drilling engineers in collaboration with mud engineers, geologists and geophysicists are looking for innovative materials to drill unconventional hydrocarbons reservoir which are distributed at the basin scale and cannot approach easily. Geo-thermal energy wells and most of unconventional reservoirs are occurred at high pressure high temperature (HPHT) conditions. Conventional micro-macro organic drilling mud additives with heat insulator in nature can minimize efficiency while drilling HPHT wells. Oil-based muds (OBM) are strictly restricted due to high toxic level and poor emulsion stability at HT. However, this review suggests that addition of macro size organic particles and inorganic nanoparticles can enhance rheological performance, reduce filtrate loss volume and improve shale inhibition characteristics of environmental friendly water-based mud (WBM). Despite an impressive amount of experimental work has been done over drilling additives and their effect over rheological and shale inhibition, taking into account their literature review are rare. In addition, there is no review work of the knowledge gained to date. This work will hope fully trigger further development and new research topics in the area of drilling muds system.

• 44.
Department of Mathematics and Computer Science, Physical Sciences and Earth Sciences, University of Messina.
of Ancient and Modern Civilizations, University of Messina. Department of Mathematics and Computer Science, Physical Sciences and Earth Sciences, University of Messina. Department of Mathematics and Computer Science, Physical Sciences and Earth Sciences, University of Messina. Department of Management Engineering - Engineering Systems Division at the Technical University of Denmark. DIIES Department, University of Reggio Calabria Via Graziella. DICEAM Department, University of Reggio Calabria Via Graziella. Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
An empirical comparison of algorithms to find communities in directed graphs and their application in Web Data Analytics2017Ingår i: IEEE Transactions on Big Data, E-ISSN 2332-7790, Vol. 3, nr 3, s. 289-306Artikel i tidskrift (Refereegranskat)

Detecting communities in graphs is a fundamental tool to understand the structure of Web-based systems and predict their evolution. Many community detection algorithms are designed to process undirected graphs (i.e., graphs with bidirectional edges) but many graphs on the Web - e.g. microblogging Web sites, trust networks or the Web graph itself - are often directed. Few community detection algorithms deal with directed graphs but we lack their experimental comparison. In this paper we evaluated some community detection algorithms across accuracy and scalability. A first group of algorithms (Label Propagation and Infomap) are explicitly designed to manage directed graphs while a second group (e.g., WalkTrap) simply ignores edge directionality; finally, a third group of algorithms (e.g., Eigenvector) maps input graphs onto undirected ones and extracts communities from the symmetrized version of the input graph. We ran our tests on both artificial and real graphs and, on artificial graphs, WalkTrap achieved the highest accuracy, closely followed by other algorithms; Label Propagation has outstanding performance in scalability on both artificial and real graphs. The Infomap algorithm showcased the best trade-off between accuracy and computational performance and, therefore, it has to be considered as a promising tool for Web Data Analytics purposes.

• 45.
Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
Crystallization of NBA-ZSM-5 from kaolin2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)

ZSM-5 is an aluminosilicate zeolite with high Si/Al ratio with suitable properties for catalysis, ion exchange, adsorption and membrane applications. The main goal of this thesis was to study the growth of ZSM-5 zeolite crystals from inexpensive natural sources of silica and alumina, as well as n-butylamine (NBA) as a low-cost structure directing agent.

The first objective of this work was to develop pathways to synthesize ZSM-5 crystals from kaolin clay or diatomaceous earth, two inexpensive natural sources of silica and alumina (Paper I). In the case of kaolin, a heat treatment was used in order to form amorphous metakaolinite. Subsequently, dealumination of the raw materials by acid leaching made it possible to reach appropriate Si/Al ratios and to reduce the amount of impurities. Finally, leached metakaolinite or diatomaceous earth was reacted with sodium hydroxide and NBA. After synthesis optimization, both sources of aluminosilicates were found to behave differently during the course of synthesis and to lead to slightly different reaction products. The final products exhibited Si/Al ratios in the range 10-20. The use of leached diatomaceous earth allowed to reach higher yield of ZSM-5 crystals within comparable synthesis times. However, low amounts of mordenite were inevitably formed as a by-product, which was related to the high calcium content of diatomaceous earth. Therefore, the rest of the thesis focused on the kaolin system.

In order to study the growth mechanism of ZSM-5 from leached metakaolinite, a proper methodology to gain local compositional data by energy dispersive spectroscopy (EDS) on aluminosilicates was developed (Paper II). Zeolite A was used as a model system that could be ion-exchanged with various elements. In order to evaluate the reliability of the measurements, inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) and EDS were compared. The EDS method developed in this work resulted in molar ratios very close to theoretical values and was therefore found more reliable than ICP-SFMS. Therefore, the method developed for zeolite A was applied in the rest of the thesis work to study the formation and growth of ZSM-5 crystals.

The second part of this work focused on the kaolin system in order to understand the nucleation and growth processes of the ZSM-5 crystals. This system was heterogeneous, due to the formation of a gel upon heating of the synthesis mixture. First, the internal structure of the gel was investigated (Paper III). Second, a kinetic study was performed and compared with microstructural observations (Paper IV). Finally, the mechanisms leading to Al-zoning and dendritical growth of the zeolite crystals were investigated (Paper V). The characterization of the intermediate phases during the different stages of the hydrothermal synthesis were analyzed by different analytical techniques, such as inductively coupled plasma-sector field mass spectrometry (ICP-SFMS), dynamic light scattering (DLS), extreme high resolution-scanning electron microscopy (XHR-SEM), energy dispersive spectroscopy (EDS), high resolution-transmission electron microscopy (HR-TEM), X-ray diffraction (XRD) and nitrogen gas adsorption.

These investigations led to several important conclusions: 1) The walls of the gel were shown for the first time to be inhomogeneous and to possess a biphasic internal structure consisting of a mesoporous skeleton of aluminosilicate nanoparticles embedded in a silicate-rich soluble matrix of soft matter. 2) The kinetic study and microstructural evidences indicated that the early crystals were fully embedded inside the gel phase and that crystal growth was retarded, as the formation of the gel occurred simultaneously with the early growth of the crystals. Hence, nucleation and growth appeared to be solution mediated.  3) Finally, the Al zoning of the crystals was related to the biphasic internal structure of the gel, since the silicate-rich matrix was preferentially consumed first. 4) The dendrites present at the surface of the crystals during most of the growth process were shown to be caused by the presence of a web of nanoparticles, most likely originating from the mesoporous skeleton inside the gel.

In the future, these findings are expected to lead to optimized synthesis pathways of catalysts with homogeneous properties and to contribute to the development of poor regions in Bolivia.

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• 46.
Luleå tekniska universitet, Institutionen för system- och rymdteknik.
Data Analysis of Earth Observation Data from Copernicus Satellites2020Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)

Open Data Cubes are platforms that contain open source satellite data and provide analysis tools for governments or organizations. The Swedish version is known as Swedish Space Data Lab (SSDL) and this master thesis was a part of it, providing the first analysis tools of the SSDL. Within a smaller project in the SSDL a drought analysis was done for the region of Mälardalen. The thesis work consisted on developing data analysis methods using packages for machine learning and statistical analysis in Python and Jupyter Notebooks. The drought analysis consisted of a two-year comparison between 2018 and 2019 due to limitations on the data availability. It was found that first year was drier than the second. However, longer time series would be needed in order to observe trends related to possible changes in the climate.

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• 47.
Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel-Boulet, Varennes.
Institut National de la Recherche Scientifique Energie Varennes. Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, Varennes. INRS, Quebec University, Varennes, Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, Varennes. Department of Electrical and Computer Engineering, McGill University, Montreal. Department of Electrical and Computer Engineering, McGill University, Montreal. Institut National de la Recherche Scientifique Energie Varennes, INRS Centre for Energy, Materials and Telecommunications, CNR-INO SENSOR Lab, Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel-Boulet, Varennes. Department of Electrical and Computer Engineering, McGill University, Montreal. Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Institut National de la Recherche Scientifique Energie Varennes, Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel-Boulet, Varennes.
High Efficiency, Pt-free Photoelectrochemical Cells for Solar Hydrogen Generation based on “Giant” Quantum Dots2016Ingår i: Nano Energy, ISSN 2211-2855, Vol. 27, s. 265-274Artikel i tidskrift (Refereegranskat)

Quantum dot (QD) sensitized TiO2 is considered as a highly promising photoanode material for photoelectrochemical (PEC) solar hydrogen production. However, due to its limited stability, the photoanode suffers from degradation of its long-term PEC performance. Here, we report the design and characterization of a high-efficiency and long-term stable Pt-free PEC cell. The photoanode is composed of a mesoporous TiO2 nanoparticle film sensitized with “giant” core@shell QDs for PEC solar hydrogen generation. The thick shell enhances light absorption in the visible range, increases the stability of the QDs and does not inhibit charge separation, injection and transport, needed for proper operation of the device. We prepared thin films of Cu2S nanoflakes through a simple and reproducible procedure, and used them as counter-electrodes replacing the standard Pt film, resulting in equivalent performances of the PEC cell. We obtained an unprecedented photocurrent density (~10 mA/cm2) for “giant” QDs based PEC devices (and corresponding H2 generation) and a very promising stability, indicating that the proposed cell architecture is a good candidate for long-term stable QD-based PEC solar hydrogen generation.

• 48. Ahl, Martin
Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
Geochemical classification of plutonic rocks in central and northern Sweden2001Rapport (Övrigt vetenskapligt)
• 49.
Faculty of Computer Science & Information Technology, University of Malaya, Kuala Lumpur.
Faculty of Computer Science & Information Technology, University of Malaya, Kuala Lumpur. Faculty of Computer Science & Information Technology, University of Malaya, Kuala Lumpur. College of Computer and Information Sciences, King Saud University. Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
Characterizing the role of vehicular cloud computing in road traffic management2017Ingår i: International Journal of Distributed Sensor Networks, ISSN 1550-1329, E-ISSN 1550-1477, Vol. 13, nr 5Artikel i tidskrift (Refereegranskat)

Vehicular cloud computing is envisioned to deliver services that provide traffic safety and efficiency to vehicles. Vehicular cloud computing has great potential to change the contemporary vehicular communication paradigm. Explicitly, the underutilized resources of vehicles can be shared with other vehicles to manage traffic during congestion. These resources include but are not limited to storage, computing power, and Internet connectivity. This study reviews current traffic management systems to analyze the role and significance of vehicular cloud computing in road traffic management. First, an abstraction of the vehicular cloud infrastructure in an urban scenario is presented to explore the vehicular cloud computing process. A taxonomy of vehicular clouds that defines the cloud formation, integration types, and services is presented. A taxonomy of vehicular cloud services is also provided to explore the object types involved and their positions within the vehicular cloud. A comparison of the current state-of-the-art traffic management systems is performed in terms of parameters, such as vehicular ad hoc network infrastructure, Internet dependency, cloud management, scalability, traffic flow control, and emerging services. Potential future challenges and emerging technologies, such as the Internet of vehicles and its incorporation in traffic congestion control, are also discussed. Vehicular cloud computing is envisioned to have a substantial role in the development of smart traffic management solutions and in emerging Internet of vehicles

• 50.
Shaheed Banazir Bhutto University, Sheringal, Pakistan.
Computer Science Department, GGPGC No.1 Abbottabad, Pakistan. Mindgarage, University of Kaiserslautern, Germany. Al Khwarizmi Institute of Computer Science, UET Lahore, Pakistan. Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB. German Research Center for Artificial Intelligence (DFKI) in Kaiserslautern, Germany.
A Deep Learning based Arabic Script Recognition System: Benchmark on KHAT2020Ingår i: The International Arab Journal of Information Technology, ISSN 1683-3198, Vol. 17, nr 3, s. 299-305Artikel i tidskrift (Refereegranskat)

This paper presents a deep learning benchmark on a complex dataset known as KFUPM Handwritten Arabic TexT (KHATT). The KHATT data-set consists of complex patterns of handwritten Arabic text-lines. This paper contributes mainly in three aspects i.e., (1) pre-processing, (2) deep learning based approach, and (3) data-augmentation. The pre-processing step includes pruning of white extra spaces plus de-skewing the skewed text-lines. We deploy a deep learning approach based on Multi-Dimensional Long Short-Term Memory (MDLSTM) networks and Connectionist Temporal Classification (CTC). The MDLSTM has the advantage of scanning the Arabic text-lines in all directions (horizontal and vertical) to cover dots, diacritics, strokes and fine inflammation. The data-augmentation with a deep learning approach proves to achieve better and promising improvement in results by gaining 80.02% Character Recognition (CR) over 75.08% as baseline.

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