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Combinatorics for multiprocessor scheduling optimization and other contexts in computer architecture1996Conference paper (Refereed)

The method described consists of two steps. First, unnecessary programs are eliminated through a sequence of program transformations. Second, within the remaining set of programs, sometimes regarded as matrices, those where all possible combinations of synchronizations occur equally frequently are proven to be extremal. At this stage we obtain a formulation which is simple enough to allow explicit formulas to be derived. It turns out that the same method can be used for obtaining worst-case bounds on other NP-hard problems within computer architecture.

• 152.
Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Natural Sciences.
Blekinge Institute of Technology, School of Engineering, Department of Systems and Software Engineering.
Generalizations of the floor and ceiling functions using the Stern-Brocot tree2006Report (Refereed)

We consider a fundamental number theoretic problem where practial applications abound. We decompose any rational number a/b in c ratios as evenly as possible while maintaining the sum of numerators and the sum of denominators. The minimum and maximum of the ratios give rational estimates of a/b from below and from above. The case c=b gives the usual floor and ceiling functions. We furthermore define the max-min-difference, which is zero iff c≤GCD(a,b), quantifying the distance to relative primality. A main tool for investigating the properties of these quantities is the Stern-Brocot tree, where all positive rational numbers occur in lowest terms and in size order. We prove basic properties such that there is a unique decomposition that gives both the minimum and the maximum. It turns out that this decomposition contains at most three distinct ratios. The problem has arisen in a generalization of the 4/3-conjecture in computer science.

Guaranteeing Response Times for Aperiodic Tasks in Global Multiprocessor Scheduling2007In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 35, no 2, p. 135-151Article in journal (Refereed)

We provide a constant time schedulability test for an on-line multiprocessor server handling aperiodic tasks. Dhall's effect is avoided by dividing the tasks in two priority classes based on task utilization: heavy and light. We prove that if the load on the multiprocessor server stays below U threshold = 3 - root 7 approximately equals 35.425%, the server can accept an incoming aperiodic task and guarantee that the deadlines of all accepted tasks will be met. The same number 35.425% is also a threshold for a task to be characterized as heavy. The bound U threshold = 3 - root 7 approximately equals 35.425% is easy-to-use, but not sharp if we know the number of processors in the multiprocessor system. Assuming the server to be equipped with m processors, we calculate a formula for the sharp bound U threshold (m), which converges to U threshold from above as m -> infinity . The results are based on a utilization function u(x) = 2(1 - x)/(2 + root 2+2x). By using this function, the performance of the multiprocessor server can in some cases be improved beyond U threshold(m) by paying the extra overhead of monitoring the individual utilization of the current tasks.

Optimal combinatorial functions comparing multiprocess allocation performance in multiprocessor systems2000In: SIAM journal on computing (Print), ISSN 0097-5397, E-ISSN 1095-7111, p. 1816-1838Article in journal (Refereed)

For the execution of an arbitrary parallel program P, consisting of a set of processes with any executable interprocess dependency structure, we consider two alternative multiprocessors. The first multiprocessor has q processors and allocates parallel programs dynamically; i.e., processes may be reallocated from one processor to another. The second employs cluster allocation with k clusters and u processors in each cluster: here processes may be reallocated within a cluster only. Let T-d(P, q) and T-c(P, k, u) be execution times for the parallel program P with optimal allocations. We derive a formula for the program independent performance function [GRAPHICS] Hence, with optimal allocations, the execution of P can never take more than a factor G(k, u, q) longer time with the second multiprocessor than with the first, and there exist programs showing that the bound is sharp. The supremum is taken over all parallel programs consisting of any number of processes. Overhead for synchronization and reallocation is neglected only. We further present a tight bound which exploits a priori knowledge of the class of parallel programs intended for the multiprocessors, thus resulting in a sharper bound. The function g(n, k, u, q) is the above maximum taken over all parallel programs consisting of n processes. The functions G and g can be used in various ways to obtain tight performance bounds, aiding in multiprocessor architecture decisions.

Optimal Combinatorial Functions Comparing Multiprocess Allocation Performance in Multiprocessor Systems1993Report (Other academic)

For the execution of an arbitrary parallel program P, consisting of a set of processes, we consider two alternative multiprocessors. The first multiprocessor has q processors and allocates parallel programs dynamically, i.e. processes may be reallocated from one processor to another. The second employs cluster allocation with k clusters and u processors in each cluster - here processes may be reallocated within a cluster only. Let T_d(P,q) and T_c (P,k,u) be execution times for the parallel program P with optimal allocations. We derive a formula for the program independent performance function G(k,u,q)=\sup_ all parallel programs P T_c(P,k,u)}{T_d(P,q)}. Hence, with optimal allocations, the execution of $P$ can never take more than a factor $G(k,u,q)$ longer time with the second multiprocessor than with the first, and there exist programs showing that the bound is sharp. The supremum is taken over all parallel programs consisting of any number of processes. Any interprocess dependency structure is allowed for the parallel programs, except deadlock. Overhead for synchronization and reallocation is neglected only. We further present optimal formulas which exploits a priori knowledge of the class of parallel programs intended for the multiprocessor, thus resulting in sharper optimal bounds. The function g(n,k,u,q) is the above maximum taken over all parallel programs consisting of n processes. The function s(n,v,k,u) is the same maximum, with q=n, taken over all parallel programs of $n$ processes which has a degree of parallelism characterized by a certain parallel profile vector v=(v_1,...,v_n). The functions can be used in various ways to obtain optimal performance bounds, aiding in multiprocessor architecture decisions. An immediate application is the evaluation of heuristic allocation algorithms. It is well known that the problems of finding the corresponding optimal allocations are NP-complete. We thus in effect present a methodology to obtain optimal control of NP-complete scheduling problems.

Optimal Scheduling Results for Parallel Computing1996In: Applications on advanced architecture computers / [ed] Astfalk, Greg, Philadelphia, USA: SIAM , 1996, p. 155-164Chapter in book (Refereed)

Load balancing is one of many possible causes of poor performance on parallel machines. If good load balancing of the decomposed algorithm or data is not achieved, much of the potential gain of the parallel algorithm is lost to idle processors. Each of the two extremes of load balancing - static allocation and dynamic allocation - has advantages and disadvantages. This chapter illustrates the relationship between static and dynamic allocation of tasks.

Optimal Worst Case Formulas Comparing Cache Memory Associativity1995Report (Other academic)

Consider an arbitrary program $P$ which is to be executed on a computer with two alternative cache memories. The first cache is set associative or direct mapped. It has $k$ sets and $u$ blocks in each set, this is called a (k,u)$-cache. The other is a fully associative cache with$q$blocks - a$(1,q)$-cache. We present formulas optimally comparing the performance of a$(k,u)$-cache compared to a$(1,q)$-cache for worst case programs. Optimal mappings of the program variables to the cache blocks are assumed. Let$h(P,k,u)$denote the number of cache hits for the program$P$, when using a$(k,u)$-cache and an optimal mapping of the program variables of$P$to the cache blocks. We establish an explicit formula for the quantity $$\inf_P \frac{h(P,k,u)}{h(P,1,q)},$$ where the infimum is taken over all programs$P$which contain$n$variables. The formula is a function of the parameters$n,k,u$and$q$only. We also deduce a formula for the infimum taken over all programs of any number of variables, this formula is a function of$k,u$and$q$. We further prove that programs which are extremal for this minimum may have any hit ratio, i.e. any ratio$h(P,1,q)/m(P)$. Here$m(P)$is the total number of memory references for the program P. We assume the commonly used LRU replacemant policy, that each variable can be stored in one memory block, and is free to be stored in any block. Since the problems of finding optimal mappings are NP-hard, the results provide optimal bounds for NP-hard quantities. The results on cache hits can easily be transformed to results on access times for different cache architectures. • 158. Lennerstad, Håkan Optimal worst case formulas comparing cache memory associativity2000In: SIAM journal on computing (Print), ISSN 0097-5397, E-ISSN 1095-7111, p. 872-905Article in journal (Refereed) In this paper we derive a worst case formula comparing the number of cache hits for two different cache memories. From this various other bounds for cache memory performance may be derived. Consider an arbitrary program P which is to be executed on a computer with two alternative cache memories. The rst cache is set-associative or direct-mapped. It has k sets and u blocks in each set; this is called a (k, u)-cache. The other is a fully associative cache with q blocks-a (1, q)-cache. We derive an explicit formula for the ratio of the number of cache hits h(P, k, u) for a(k, u)-cache compared to a (1, q)-cache for a worst case program P. We assume that the mappings of the program variables to the cache blocks are optimal. The formula quantifies the ratio [GRAPHICS] where the in mum is taken over all programs P with n variables. The formula is a function of the parameters n, k, u, and q only. Note that the quantity h ( P, k, u) is NP-hard. We assume the commonly used LRU (least recently used) replacement policy, that each variable can be stored in one memory block, and that each variable is free to be mapped to any set. Since the bound is decreasing in the parameter n, it is an optimal bound for all programs with at most n variables. The formula for cache hits allows us to derive optimal bounds comparing the access times for cache memories. The formula also gives bounds ( these are not optimal, however) for any other replacement policy, for direct-mapped versus set-associative caches, and for programs with variables larger than the cache memory blocks. • 159. Lundberg, Lars An Optimal Upper Bound on the Minimal Completion Time in Distributed Supercomputing1994Conference paper (Refereed) We first consider an MIMD multiprocessor configuration with n processors. A parallel program, consisting of n processes, is executed on this system-one process per processor. The program terminates when all processes are completed. Due to synchronizations, processes may be blocked waiting for events in other processes. Associated with the program is a parallel profile vector nu , index i (1<or=i<or=n) in this vector indicates the percentage of the total execution time when i processes are executing. We then consider a distributed MIMD supercomputer with k clusters, containing u processors each. The same parallel program, consisting of n processes, is executed on this system. Each process can only be executed by processors in the same cluster. Finding a schedule with minimal completion time in this case is NP-hard. We are interested in the gain of using n processors compared to using k clusters containing u processors each. The gain is defined by the ratio between the minimal completion time using processor clusters and the completion time using a schedule with one process per processor. We present the optimal upper bound for this ratio in the form of an analytical expression in n, nu , k and u. We also demonstrate how this result can be used when evaluating heuristic scheduling algorithms (12 Refs.) • 160. Lundberg, Lars Bounding the gain of changing the number of memory modules in shared memory multiprocessors1997In: Nordic Journal of Computing, ISSN 1236-6064, Vol. 4, no 3, p. 233-58Article in journal (Refereed) We consider a multiprocessor, with p processors and m memory modules. If more than one processor want to access a memory module simultaneously, these accesses will be serialized due to memory contention. The completion time of a program executing on this system is thus affected by the way addresses are mapped onto memory modules, and finding a mapping which results in minimal completion time is NP-hard. If we change the number of memory modules from m to m’, while keeping the number processors constant, we will generally change the minimal completion time. The gain of changing the number of memory modules from m to m’ for a certain program is defined as the ratio between the minimal completion times, using m and m’ modules respectively. Here, we present an optimal upper bound on the maximum gain of changing the number of memory modules, as a function of m, m’ and p, including the case when m’ is infinitely large. The bound is obtained by investigating a mathematical formulation. The mathematical tools involved are essentially elementary combinatorics. The formula for calculating the bound is mathematically complicated but can be rapidly computed for reasonable m, m’ and p. This bound makes it possible to do price-performance trade-offs and to compare any mapping of addresses to memory modules with the optimal case. The results are applicable to different multiprocessor architectures, e.g. systems with crossbar networks and systems with multiple buses. The results also make it possible to calculate optimal performance bounds for multiprocessors containing cache memories: as well as for multiprocessors with no cache memories. Moreover, we discuss how the results can be used for calculating bounds for programs with as well as without synchronizations. • 161. Lundberg, Lars Comparing the optimal performance of different MIMD multiprocessor architectures1998Conference paper (Refereed) We compare the performance of systems consisting of one large cluster containing q processors with systems where processors are grouped into k clusters containing u processors each. A parallel program, consisting of n processes, is executed on this system. Processes may be relocated between the processors in a cluster. They may,however not be relocated from one cluster to another. The performance criterion is the completion time of the parallel program. We present two functions: g(n,k,u,q) and G(k,u,q). Provided that we can find optimal or near optimal schedules,these functions put optimal upper bounds on the gain of using one cluster containing q processors compared to using k clusters containing u processors each. The function g(n,k,u,q) is valid for programs with n processes, whereas G(k,u,q) only depends on the two multiprocessor architectures. By evaluating g(n,k,u,q) and G(k,u,q) we show that the gain of increasing the cluster size from 1 to 2 and from 2 to 4 is relatively large. However, the gain of using clusters larger than 4 is very limited. • 162. Lundberg, Lars Using Golomb Rulers for Minimizing Collisions in Closed Hashing2004Conference paper (Refereed) We give conditions for hash table probing which minimize the expected number of collisions. A probing algorithm is determined by a sequence of numbers denoting jumps for an item during multiple collisions. In linear probing, this sequence consists of only ones – for each collision we jump to the next location. To minimize the collisions, it turns out that one should use the Golomb ruler conditions: consecutive partial sums of the jump sequence should be distinct. The commonly used quadratic probing scheme fulfils the Golomb condition for some cases. We define a new probing scheme – Golomb probing - that fulfills the Golomb conditions for a much larger set of cases. Simulations show that Golomb probing is always better than quadratic and linear and in some cases the collisions can be reduced with 25% compared to quadratic and with more than 50% compared to linear. • 163. Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems. Dynamic Channel Allocation in GSM Network2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis The rapid evolution of cellular technology and the more user demand for advanced mobile services leads the industry to develop more efficient network structures. The increasing number of cellular subscribers and the demand for cellular networks communication (3rd and 4th generation) drives to the research of the new methodologies for the design of cellular networks and services. This thesis has been generated and complied with the objective of proposing GSM Network Utilizing DYNAMIC CHANNEL ALLOCATION starting with the architecture of GSM Network with system design. In next chapter we define the channels that are transmitted over the Air Interface, leading further towards the Channel Allocation Schemes in GSM. In this chapter we describe the various types of channels are used in GSM Network. Furthermore define the main two strategies for channel assignment, briefly differentiate between the FCA (Fixed Channel Allocation) and (Dynamic Channel Allocation) as well as advantages of both schemes. Then the major is study of (Dynamic Channel Allocation) and the proposed Algorithm for Dynamic Channel Allocation in GSM network is presented and discussed. All channels will placed in a pool and on demand or on request will be assigned to the user for that particular call that will be helpful to maintain the grade of service and increase system capacity. • 164. Blekinge Institute of Technology, School of Engineering. Inexact Programming2012Independent thesis Advanced level (degree of Master (Two Years))Student thesis Two types of fuzzy linear programming i.e. fuzzy number linear programming and interval number linear programming are used for optimization problems. In interval form of linear programming we convert the inequalities from the feasible region, containing intervals as coefficients, to two groups of inequalities characterized by real, exact coefficients values. Then classical programming has been used to achieve an optimal solution in the feasible region. In fuzzy number linear programming, α‐cuts and LR forms of fuzzy numbers as coefficients have been used to find optimal solution in the feasible region. Finally the numerical examples and their solutions are attached to provide explanations of procedures. • 165. Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Natural Sciences. Mathematical Modelling of The Global Positioning System Tracking Signals2008Independent thesis Advanced level (degree of Master (One Year))Student thesis Recently, there has been increasing interest within the potential user community of Global Positioning System (GPS) for high precision navigation problems such as aircraft non precision approach, river and harbor navigation, real-time or kinematic surveying. In view of more and more GPS applications, the reliability of GPS is at this issue. The Global Positioning System (GPS) is a space-based radio navigation system that provides consistent positioning, navigation, and timing services to civilian users on a continuous worldwide basis. The GPS system receiver provides exact location and time information for an unlimited number of users in all weather, day and night, anywhere in the world. The work in this thesis will mainly focuss on how to model a Mathematical expression for tracking GPS Signal using Phase Locked Loop filter receiver. Mathematical formulation of the filter are of two types: the first order and the second order loops are tested successively in order to find out a compromised on which one best provide a zero steady state error that will likely minimize noise bandwidth to tracks frequency modulated signal and returns the phase comparator characteristic to the null point. Then the Z-transform is used to build a phase-locked loop in software for digitized data. Finally, a Numerical Methods approach is developed using either MATLAB or Mathematica containing the package for Gaussian elimination to provide the exact location or the tracking of a GPS in the space for a given a coarse/acquisition (C/A) code. • 166. Mbiydzenyuy, Gideon Assessment of Telematic Systems for Road Freight Transport2010Licentiate thesis, comprehensive summary (Other academic) The focus of this thesis is the assessment of telematic systems for road freight transport from a planning perspective. The aim is to support strategic decisions related to architectural choices for such systems, with the possibility to achieve synergies by supporting multiple telematic services. The past decade has witnessed enormous growth in cargo volumes resulting in increasing demand for transport capacity. To match this increasing demand only with expansion of infrastructure, e.g. road and vehicles, does not seem to be a sustainable strategy. One of the few approaches with the potential to improve the use of current transport capacity is the integrated use of modern information and communication technology, otherwise known as telematic systems for road transport, an important component within Intelligent Transport Systems (ITS). This type of systems can deliver multiple services that can be used to improve the efficiency and safety of road freight transport. However, attempts to unleash the potential of telematic systems and make maximum possible use of the available transport capacity have been hindered by several challenges ranging from planning and design to development and deployment. Considering the large scope of possible telematic services that can potentially be deployed in road freight transport, this thesis suggests a framework in order to enable structured assessment of telematic systems. Based on the suggested framework, a set of potential transport telematic services are identified and a method for quantifying the value of the services to society is developed. The suggested method takes into account the expected impact on different transportation challenges, such as accidents, fuel consumption, and infrastructure maintenance. Quantitative methods are provided for studying the value of services sharing a common infrastructure. Using quantified benefits of services and costs of various functionalities required by telematic services, the concept of a multi-service architecture is investigated using optimization methods, which handles the multi-dimensional relations between different services that are otherwise difficult to analyze with traditional cost-benefit analysis. The analyses show which telematic services can be achieved with different approaches, such as vehicle-to-vehicle communication, vehicle-to-infrastructure communication, etc. Although multi-service architectures are promising, several challenges need to be overcome, including security, service quality, privacy, and business models. The knowledge gained from the work presented in this thesis can be valuable for different stakeholders, such as governments, service providers, and transport service users, in fostering the planning, design, development, and deployment of telematic systems in transport. • 167. Mbiydzenyuy, Gideon Toward Cost-Efficient Integration of Telematic Systems Using K-Spanning Tree and Clustering Algorithms2011Conference paper (Refereed) This article uses analytical methods to assess reductions in total costs of telematic systems that can result from common infrastructure utilization. Analytical methods based on clustering and K-minimum spanning tree can be adopted for finding clusters or sets which maximize reductions in total system costs due to infrastructure sharing between telematic systems. Efficient integration of telematic systems through infrastructure sharing can positively influence telematic service interoperability while reducing costs. Results show the measure of synergy for each K-value, as well as total cost savings of up to 2%. • 168. Meleshko, Sergey Symmetries of Integro-Differential Equations2010, XIIIBook (Other academic) This book aims to coherently present applications of group analysis to integro-differential equations in an accessible way. The book will be useful to both physicists and mathematicians interested in general methods to investigate nonlinear problems using symmetries. Differential and integro-differential equations, especially nonlinear, present the most effective way for describing complex processes. Therefore, methods to obtain exact solutions of differential equations play an important role in physics, applied mathematics and mechanics. This book provides an easy to follow, but comprehensive, description of the application of group analysis to integro-differential equations. The book is primarily designed to present both fundamental theoretical and algorithmic aspects of these methods. It introduces new applications and extensions of the group analysis method. The authors have designed a flexible text for postgraduate courses spanning a variety of topics. • 169. Melin, Jan Two types of limit cycles of a resonant converter modelled by a three-dimensional system2008In: Nonlinear Analysis: Hybrid Systems, ISSN 1751-570X, E-ISSN 1878-7460, Vol. 2, no 4, p. 1275-1286Article in journal (Refereed) In this paper, the long-run dynamics of a controlled resonant converter, modelled as a piecewise system, is studied. The modelling of the resonant converter can be done using various approximations and the long-run dynamics of the two dimensional cases were earlier analysed. In this paper, we discuss results that can be extended to the three dimensional case. It seems that limit cycles describe the longrun dynamics in important situations in the three dimensional case, too. Our objective is to relate the limit cycles found previously in the two-dimensional case to those found now in the three dimensional approximation. • 170. Blekinge Institute of Technology, School of Engineering. Eigen Fuzzy Sets of Fuzzy Relation with Applications2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis Eigen fuzzy sets of fuzzy relation can be used for the estimation of highest and lowest levels of involved variables when applying max-min composition on fuzzy relations. By the greatest eigen fuzzy sets (set which can be greater anymore) maximum membership degrees of any fuzzy set can be found, with the help of least eigen fuzzy set (set which can be less anymore) minimum membership degrees of any fuzzy sets can be found as well.The lowest and highest level, impact or e ffect of anything can be found by applying eigen fuzzy set theory. The implicational aspect of this research study is medical and customer satisfaction level measurement. By applying methods of eigen fuzzy set theory the e ffectiveness of medical cure and customer satisfaction can be found with high precision. • 171. Blekinge Institute of Technology, School of Engineering. Investigation of the Equations Modelling Chemical Waves Using Lie Group Analysis2012Independent thesis Advanced level (degree of Master (Two Years))Student thesis A system of nonlinear di fferential equations, namely, the Belousov-Zhabotinskii reaction model has been investigated for nonlinear self-adjointness using the recent work of Professor N.H.Ibragimov. It is shown that the model is not nonlinearly self-adjoint. The symmetries of the system and nonlinear conservation laws are calculated. The modi fied system, which is nonlinearly self-adjoint, is also analysed. Its symmetries and conservation laws are presented. • 172. Blekinge Institute of Technology, Department of Telecommunications and Mathematics. Blekinge Institute of Technology, Department of Telecommunications and Mathematics. Tight Bounds on the Minimum Euclidean Distance for Block Coded Phase Shift Keying1996Report (Refereed) We present upper and lower bounds on the minimum Euclidean distance$d_{Emin}(C)$for block coded PSK. The upper bound is an analytic expression depending on the alphabet size$q$, the block length$n$and the number of codewords$|C|$of the code$C$. This bound is valid for all block codes with$q\geq4$and with medium or high rate - codes where$|C|>(q/3)^n$. The lower bound is valid for Gray coded binary codes only. This bound is a function of$q$and of the minimum Hamming distance$d_{Hmin}(B)$of the corresponding binary code$B$. We apply the results on two main classes of block codes for PSK; Gray coded binary codes and multilevel codes. There are several known codes in both classes which satisfy the upper bound on$d_{Emin}(C)$with equality. These codes are therefore best possible, given$q,n$and$|C|$. We can deduce that the upper bound for many parameters$q,n$and$|C|$is optimal or near optimal. In the case of Gray coded binary codes, both bounds can be applied. It follows for many binary codes that the upper and the lower bounds on$d_{Emin}(C)$coincide. Hence, for these codes$d_{Emin}(C)\$ is maximal.

• 173. Nilsson, Magnus
A two-metric approach to improve bounds on the minimum Euclidean distance for block codes2008Conference paper (Refereed)

We consider block coded PSK, and improve a previously established upper bound on the minimum Euclidean distance d_E(C) that is valid for any block code C. The bound is an explicit function of the alphabet size, block length and the number of code words. The improvement involves choosing an inner metric to give the best possible bound for the outer metric, which is Euclidean. we describe this approach and its problems, and present empiric results.

• 174.
Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
Mekaniska beräkningar av armeringstråd vid förläggning på högspänningskablar2014Student thesis

Detta examensarbete har tagit plats på ABB High Voltage Cables i Karlskrona och fokuserar på deras armeringsprocess (AR50) som förstärker kabeln genom påläggning av armeringstrådar. Arbetet är starkt begränsat till enbart den korta perioden för själva påläggningen av tråden och undersöker spänningsskillnader i en armeringstråd beroende på olika kabel – och tråddimensioner samt bromskrafter som används i produktionen. Studien följer en modell – och teoriutvecklande forskningsprocess kombinerat med ett utprövande resultatbildande. Studiens syfte är att tillsammans med en beräkningsmodell öka och fördjupa ABBs kunskaper kring armeringstråden som idag används för att stärka och skydda ABBs alla olika högspänningskablar. Beräkningsmodellen tas fram i FEA (Finita Element Analys) prorammet ABAQUS genom en dynamisk explicit modell. En förklaring till hur beräkningsmodellen har byggts upp och vilka parametrar som används beskrivs i rapporten. Dessa delar bidrar sedan till resultatet i studien som ger en bild av att bromskraften som används i AR50s armeringsprocessen inte behöver kontrolleras med en hög precision så länge den är tillräckligt stor för att hålla armeringstråden sträckt vid påläggningen. Studien visar också att olika kabel – och tråddimensioner inte påverkar spänningsnivåerna något markant vid armeringsprocessen och att nippeln som används i armeringsprocesen för att trycka ner armeringstråden mot kabeln bestämmer hur spänningsbilden ser ut.

• 175. Nyqvist, Robert
Algebraic Dynamical Systems, Analytical Results and Numerical Simulations2007Book (Other academic)

In this thesis we study discrete dynamical system, given by a polynomial, over both finite extension of the fields of p-adic numbers and over finite fields. Especially in the p-adic case, we study fixed points of dynamical systems, and which elements that are attracted to them. We show with different examples how complex these dynamics are. For certain polynomial dynamical systems over finite fields we prove that the normalized average of the numbers of linear factors modulo prime numbers exists. We also show how to calculate the average, by using Chebotarev's Density Theorem. The non-normalized version of the average of the number of linear factors of linearized polynomials modulo prime numbers, tends to infinity, so in that case we find an asymptotic formula instead. We have also used a computer to study different behaviors, such as iterations of polynomials over the p-adic fields and the asymptotic relation mention above. In the last chapter we present the computer programs used in different part of the thesis.

• 176.
Blekinge Institute of Technology, School of Engineering, Department of Mathematics and Science.
Asymptotic behaviour of numbers of cycles of dynamical systems in finite fields2007In: Proceedings of the Jangjeon Mathematical Society, ISSN 1598-7264, Vol. 10, no 1, p. 1-6Article in journal (Refereed)
On the Improvement of Healthcare Management Using Simulation and Optimisation2010Doctoral thesis, comprehensive summary (Other academic)

This thesis concerns healthcare management and specifically addresses the problems of operating room planning and waiting list management. The operating room department is one of the most expensive areas within the healthcare system which necessitates many expensive resources such as staff, equipment and medicine. The planning of operating rooms is a complex task involving many dependencies and conflicting factors and hence careful operating room planning is critical to attain high productivity. One part of the planning process is to determine a Master Surgery Schedule (MSS). An MSS is a cyclic timetable that specifies the allocation of the surgical groups into different blocks of operating room time. Using an optimization-based approach, this thesis investigates whether the MSS can be adapted to better meet the varying surgery demand. Secondly, an extended optimization-based approach, including post-operative beds, is presented in which different policies related to priority rules are simulated to demonstrate their affect on the average waiting time. The problem of meeting the uncertainty in demand of patient arrival, as well as surgery duration, is then incorporated. With a combination of simulation and optimization techniques, different policies in reserving operating room capacity for emergency cases together with a policy to increase staff in stand-by, are demonstrated. The results show that, by adopting a certain policy, the average patient waiting time and surgery cancellations are decreased while operating room utilization is increased. Furthermore, the thesis focuses on how different aspects of surgery pre-conditions affect different performance measures related to operating room planning. The emergency surgery cases are omitted and the studies are delimited to concern the elective healthcare process only. With a proposed simulation model, an experimental tool is offered, in which a number of analyses related to the process of elective surgeries can be conducted. The hypothesis is that, sufficiently good estimates of future surgery demand can be assessed at the referral stage. Based on this assumption, an experiment is conducted to explore how different policies of managing incoming referrals affect patient waiting times. Related to this study, possibility of using data mining techniques to find indicators that can help to estimate future surgery demand is also investigated. Finally, in parallel, an agent-based simulation approach is investigated to address these types of problems. An agent-based approach would probably be relevant to consider when multiple planners are considered. In a survey, a framework for describing applications of agent based simulation is provided.

• 178.
Blekinge Institute of Technology, School of Computing.

• 179.
Blekinge Institute of Technology, School of Engineering, Department of Systems and Software Engineering.
Association rules analysis for objects hierarchy2006Independent thesis Advanced level (degree of Master (One Year))Student thesis

Association rules are one of the most popular methods of data mining. This technique allows to discover interesting dependences between objects. The thesis concerns on association rules for hierarchy of objects. As a multi–level structure is used DBLP database, which contains bibliographic descriptions of scientific papers conferences and journals in computer science. The main goal of thesis is investigation of interesting patterns of co-authorship with respect to different levels of hierarchy. To reach this goal own extracting method is proposed.

• 180.
Blekinge Institute of Technology, School of Engineering, Department of Mechanical Engineering.
FINITE ELEMENT MODELING TO VERIFY RESIDUAL STRESS IN ORTHOGONAL MACHINING2009Independent thesis Advanced level (degree of Master (One Year))Student thesis

The aim of this thesis paper, to create a numerical model to examine the residual stresses induced by orthogonal machining in the finished work piece and the model is validated by comparing with experimental result. The finite element method is used to simulate and analyze the residual stresses induced by a orthogonal metal cutting process. A Dynamics explicit time integration technique with Arbitrary Lagrangian Eulerian (ALE) adaptive meshing Finite Element Method (FEM) is employed to simulate the model. The Johnson-Cook material model is used to describe the work material behaviour and fully coupled thermal-stress analysis are combined to realistically simulate high speed machining with an orthogonal cutting. Finite Element modelling of Residual stresses and resultant surface properties induced by round edge cutting tools is performed as case studies for high speed orthogonal machining of 20NiCrMo5 steel. As a conclusion we can say that results from 2D simulations are very close to the experimental results at the surface level, but there is bit difference when we go down in the material. In 3D simulation, results agree with the experimental values in all levels So we can say that it is possible to model residual stresses, induced by orthogonal machining with accepted amount of accuracy. Keywords Residual stress, FE-modelling, ALE formulation,3D.ABAQUS/CAE

Approximate Reasoning in Surgical Decisions2009Conference paper (Refereed)

Approximate reasoning is one of the most effective fuzzy systems. The compositional rule of inference founded on the logical law modus ponens is furnished with a true conclusion, provided that the premises of the rule are true as well. Even though there exist different approaches to an implication, being the crucial part of the rule, we modify the early implication proposed by Zadeh in our practical model concerning a medical application. The approximate reasoning system presented in this work considers evaluation of a risk in the situation when physicians weigh necessity of the operation on a patient. The patient’s clinical symptom levels, pathologically heightened, indicate the presence of a disease possible to recover by surgery. We wish to evaluate the extension of the operation danger by involving particularly designed fuzzy sets in the algorithm of approximate reasoning.

Rough set theory in the classification of diagnoses2009Conference paper (Refereed)

Rough sets, surrounded by two approximation sets filled with sure and possible members constitute perfect mathematical tools of the classification of some objects. In this work we adopt the rough technique to verify diagnostic decisions concerning a sample of patients whose symptoms are typical of a considered diagnosis. The objective is to extract the patients who surely Suffer from the diagnosis, to indicate the patients who are free from it, and even to make decisions in undefined diagnostic cases. By applying selected logical decision rules, we also discuss a possibility of reducing of symptom sets to their minimal collections preserving the previous results in order to minimize a number of numerical calculations.

Rough Sets Based on Reducts of Conditional Attributes in Medical Classification of the Diagnosis Status2008, June 1Conference paper (Refereed)

Rough sets constitute helpful mathematical tools of the classification of objects belonging to a certain universe when dividing the universe in two collections filled with sure and possible members. In this work we adopt the rough technique to verify diagnostic decisions concerning a sample of patients whose symptoms are typical of a considered diagnosis. The objective is to extract the patients who surely suffer from the diagnosis, to indicate the patients who are free from it, and even to make decisions in undefined diagnostic cases. We also consider a decisive power of reducts being minimal collections of symptoms, which preserve the previous classification results. We use them in order to minimize a number of numerical calculations in the classification process. Finally, by testing influence of symptom intensity levels on the diagnosis indisputable appearance we select these standards, whose either presence or absence in the patients allows us to add complementary remarks making the classification effects even more readable.

The Composition of the Book in Fuzzy Logic Adapted to Stationary and Distance Courses for Advanced Students2007Other (Other academic)

The project titled: “The Composition of the Book in Fuzzy Logic Adapted to Stationary and Distance Courses for Advanced Students” has been granted by the Swedish Royal Academy of Sciences in 2007 The following contents of the book “Basic Concepts and Applications of Fuzzy Set Theory” is primarily designed as: Contents 1. Introduction 2. Fuzzy sets 3. Fuzzy and linguistic variables 4. Operations on fuzzy sets 5. T and S Norms 6. Fuzzy measures and measures of fuzziness 7. Extension principles 8. Fuzzy numbers and their arithmetic 9. The L-R, interval and alpha-cut representations of fuzzy numbers 10. Fuzzy relations, The compositional rule of inference 11. The eigen sets of a fuzzy relation 12. Fuzzy analysis 13. Possibility theory, Probability of fuzzy events 14. Fuzzy logic and approximate reasoning 15. Fuzzy decision making, 16. Fuzzy control, 17. Imprecise optimization 18. Choquet and Sugeno integrals 19. Rough set theory 20. Discussion of other imprecise theories

The concept of distances between fuzzy sets as a criterion in the diagnostic process2007In: Intuitionistic Fuzzy Sets and Generalized nets, 2007Chapter in book (Refereed)
• 186.
Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
Blekinge Cty Hosp, Dept Surg & Urol, S-37185 Karlskrona, Sweden.. Czestochowa Tech Univ, Inst Comp & Informat Sci, PL-42201 Czestochowa, Poland..
The Fuzzified Quasi-Perceptron in Decision Making Concerning Treatments in Necrotizing Fasciitis2015In: ARTIFICIAL INTELLIGENCE AND SOFT COMPUTING, PT II (ICAISC 2015), Springer, 2015, p. 130-141Conference paper (Refereed)

In the current paper we mathematically try to support the decision concerning the treatment with hyperbaric oxygen for patients, suffering from necrotizing fasciitis. To accomplish the task, we involve the fuzzified model of a quasi-perceptron, which is our modification of the classical artificial simple neuron. By means of the fuzzification of input signals and output decision levels, we wish to distinguish between decisions "treatment without recommended hyperbaric oxygen" versus "treatment with hyperbaric oxygen". The number of decision levels can be arbitrary in order to extend the decision scale.

• 187.
Blekinge Institute of Technology, School of Engineering.
Blekinge Institute of Technology, School of Engineering.
DETECTION OF VACANT FREQUENCY BANDS IN COGNITIVE RADIO2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis

• 188.
Blekinge Institute of Technology, School of Engineering, Department of Mechanical Engineering.
Absorption of intense regular and noise waves in relaxing media2014In: Acoustical Physics, ISSN 1063-7710, E-ISSN 1562-6865, Vol. 60, no 5, p. 499-505Article in journal (Refereed)

An integro-differential equation is written down that contains terms responsible for nonlinear absorption, visco-heat-conducting dissipation, and relaxation processes in a medium. A general integral expression is obtained for calculating energy losses of the wave with arbitrary characteristics-intensity, profile (frequency spectrum), and kernel describing the internal dynamics of the medium. It is shown that for weak waves, the general integral leads to well-known results of a linear approximation. Profiles of stationary solutions are constructed both for an exponential relaxation kernel and for other types of kernels. Energy losses at the front of week shock waves are calculated. General integral formulas are obtained for energy losses of intense noise, which are determined by the form of the kernel, the structure of the noise correlation function, and the mean square of the derivative of realization of a random process

• 189. Rudenko, Oleg
Nonlinear Dynamics of Grains in a Liquid-Saturated Soil2003In: Nonlinear dynamics, ISSN 0924-090X, E-ISSN 1573-269X, Vol. 35, no 2, p. 187-200Article in journal (Refereed)

A new kind of nonlinearity of inertial type caused by accelerated motion of interacting particles is described. The model deals with an ensemble of grains immersed into a vibrating fluid. First, the nonlinear vibration of two connected grains is studied. The temporal behaviours of displacement and velocity, as well as spectrum of vibration, are analysed. Numerical simulations are performed. Then an infinite chain of grains is considered and the corresponding differential-difference equation is derived. For the continuum limit the inhomogeneous nonlinear wave equation is solved and temporal profiles are calculated. A new resonant phenomenon is described and the resonant curves are constructed.

• 190.
Blekinge Institute of Technology, School of Engineering, Department of Mechanical Engineering.
Blekinge Institute of Technology, School of Engineering, Department of Mechanical Engineering.
The phenomenon of self-trapping of a strongly nonlinear wave.2014In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 135, no 4Article in journal (Refereed)

Self means here an effect of a wave on itself. Several self-action phenomena are known in nonlinear wave physics. Among them are self-focusing of beams self-compression of light pulses self-channeling self-reflection (or self-splitting) waves with shock fronts self-induced transparency and self-modulation. These phenomena are known for weakly nonlinear waves of different physical origin. Our presentation at ASA meeting in Montreal [POMA 19 045080 (2013)] was devoted to strongly nonlinear waves having no transition to the linear limit at infinitesimally small amplitudes. Such waves can demonstrate particle-like properties. Self-trapping consists of the arrest of wave propagation and in the formation of a localized state. In particular the model generalizing the Heisenberg' ordinary differential equation to spatially distributed systems predicts periodic oscillations but no traveling waves. Different models for strongly nonlinear waves will be considered and some unusual phenomena will be discussed. Preliminary results were published in Ac. Phys. 59 584 (2013) and Physics-Uspekhi (Adv. Phys. Sci.) 183 683 (2013). [This work was supported by the Megagrant No.11.G34.31.066 (Russia) and the KK Foundation (Sweden).

• 191.
Blekinge Institute of Technology, School of Engineering.
Developing Real Time Automatic Step Detection in the three dimensional Accelerometer Signal implemented on a Microcontroller System2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis

Parkinson’s disease is associated with reduced coordination between respiration and locomotion. For the neurological rehabilitation research, it requires a long-time monitoring system, which enables the online analysis of the patient’s vegetative locomotor coordination. In this work a real time step detector using three-dimensional accelerometer signal for the patients with Parkinson‘s disease is developed. This step detector is a complement for a recently developed system included of intelligent, wirelessly communicating sensors. The system helps to focus on the scientific questions whether this coordination may serve as a measure for the rehabilitation progress of PD patients.

• 192.
Blekinge Institute of Technology, School of Computing.
Mapping of User Quality-of-Experience to Application Perceived Performance for Web Application.2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis

Web browsing posses a major share among the activities on the Internet. Heavy usage of web browsing makes the Web Quality of Experience (QoE) one of the critical factor in deciding the overall success of network services. Amongst others, Web QoE can be effected by the delays in network that can result in higher application download times. In this thesis work, an effort has been made to map applications level download times to Quality of Experience. A subjective analysis on how the user takes into account the domain of web browsing has been carried out. For this purpose a testbed was developed at Blekinge Institute of Technology on which different users were tested. Specific sequences of delays were introduced on the network which resulted in desired application download times. Regression analysis was performed and a mapping between user QoE and application download times was carried out. Based on the results conclusions were made which are presented in this thesis report.

• 193.
Blekinge Institute of Technology, School of Engineering.
Fuzzy decision making using max-min and MMR methods2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis

Fuzzy logic is based on the theory of fuzzy sets, where an object’s membership of a set is gradual rather than just member or not a member. Fuzzy logic uses the whole interval of real numbers between zero (False) and one (True) to develop a logic as a basis for rules of inference. Particularly the fuzzified version of the modus ponens rule of inference enables computers to make decisions using fuzzy reasoning rather than exact. We study decision making problem under uncertainty. we analyze Max-Min method and Minimization of regret method originally developed by Savage and further developed by Yager. We generalize The MMR method by creating the parameterized family of minimum regret methods by using the ordered weighted averaging OWA operators.

• 194.
Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences.
Application of Ibragimov's method and Noether's theorem for constructing conservation laws of the linear elasticity model2014Independent thesis Advanced level (degree of Master (Two Years))Student thesis

In this thesis, conservation laws of the Lame equation describing linear elasticity have been constructed. This has been done by the implementation of two theorems for constructing conservation laws: the new theorem suggested by N H.Ibragimov, and the classical theorem presented by E.Noether. As a result one can see that the Ibragimov method provides more conservation laws than the Noether theorem, which may suggest the better efficiency of the Ibragimov method.

• 195.
Blekinge Institute of Technology, School of Engineering, Department of Systems and Software Engineering.
Web links utility assessment using data mining techniques2006Independent thesis Advanced level (degree of Master (One Year))Student thesis

This paper is focusing on the data mining solutions for the WWW, specifically how it can be used for the hyperlinks evaluation. We are focusing on the hyperlinks used in the web sites systems and on the problem which consider evaluation of its utility. Since hyperlinks reflect relation to other webpage one can expect that there exist way to verify if users follow desired navigation paths. The Challenge is to use available techniques to discover usage behavior patterns and interpret them. We have evaluated hyperlinks of the selected pages from www.bth.se web site. By using web expert’s help the usefulness of the data mining as the assessment basis was validated. The outcome of the research shows that data mining gives decision support for the changes in the web site navigational structure.

• 196. Sochor, Jana
Blekinge Institute of Technology, School of Computing.
Assessing the Benefits of Intelligent Truck Parking2011Conference paper (Refereed)

The aim of this paper is to identify and provide a discussion about aspects related to benefits of Intelligent Truck Parking (ITP) for Heavy Goods Vehicles (HGVs) and their effects on different stakeholders. Most existing work has narrowly focused on benefits for private cars and does not include the user perspective. In this paper, a review of previous work helps identify benefit areas and stakeholder groups relevant for HGV transport. These benefit areas are then theoretically assessed and compared for different stakeholders. Additionally, interview results of Swedish drivers’ and companies’ perceptions of the ITP service are presented. Comparing results of the interviews with the theoretical assessment indicates that the end users may not perceive ITP as highly beneficial although they theoretically benefit the most. Companies, particularly national haulage companies, expressed a low willingness to pay for the service. The general conclusion is that the ITP service has a better chance of success as part of a package of services rather than as a stand-alone service.

• 197.
Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
Analysis of MIG Welding with Aim on Quality2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis

Since 1987 Uddcomb Engineering has repaired pulps by their own developed overlay welding method even called Uddcomb method. Currently each welding machine is operated by two persons. To increase Uddcomb Engineering competitiveness the reduced number of operators is desired. An installation of a monitoring system which can aid humans in the welding quality control also helps to improve company’s position. A future goal would be to make this monitoring system automatic without a human operator in the loop. In this thesis, arc voltage, weld current and audio signals were collected and analyzed with aim on finding algorithms to monitor the quality of the welding process. The use of statistics tools is the basis for detecting variations in the voltage and current data, associated with welding process. It has been shown that voltage signal can be used as a part of the welding quality control. The audio signal from welding at low frequencies varies with the speed of the process. The signal can also be incorporated in the monitoring of the process. The use of filters, growing sums and statistics are key elements in the algorithms presented in this report.

• 198.
Blekinge Institute of Technology, School of Engineering.
Optimal system of subalgebras and invariant solutions for a nonlinear wave equation2009Independent thesis Advanced level (degree of Master (Two Years))Student thesis

This thesis is devoted to use Lie group analysis to obtain all invariant solutions by constructing optimal system of one-dimensional subalgebras of the Lie algebra L5 for a nonlinear wave equation. I will show how the given symmetries ( Eq.2) are admitted by using partial differential equation (Eq.1), In addition to obtain the commutator table by using the same given symmetries. Subsequently, I calculate the transformations of the generators with the Lie algebra L5, which provide the 5-parameter group of linear transformations for the operators. Finally, I construct the invariant solutions for each member of the optimal system.

• 199.
Blekinge Institute of Technology, School of Engineering.
Mathematicle Modelling and Applications of Particle Swarm Optimization2011Independent thesis Advanced level (degree of Master (Two Years))Student thesis

Optimization is a mathematical technique that concerns the finding of maxima or minima of functions in some feasible region. There is no business or industry which is not involved in solving optimization problems. A variety of optimization techniques compete for the best solution. Particle Swarm Optimization (PSO) is a relatively new, modern, and powerful method of optimization that has been empirically shown to perform well on many of these optimization problems. It is widely used to find the global optimum solution in a complex search space. This thesis aims at providing a review and discussion of the most established results on PSO algorithm as well as exposing the most active research topics that can give initiative for future work and help the practitioner improve better result with little effort. This paper introduces a theoretical idea and detailed explanation of the PSO algorithm, the advantages and disadvantages, the effects and judicious selection of the various parameters. Moreover, this thesis discusses a study of boundary conditions with the invisible wall technique, controlling the convergence behaviors of PSO, discrete-valued problems, multi-objective PSO, and applications of PSO. Finally, this paper presents some kinds of improved versions as well as recent progress in the development of the PSO, and the future research issues are also given.

• 200.
Blekinge Institute of Technology, School of Engineering.
Takagi-Sugeno and Mamdani Fuzzy Control of a Resort Management System2012Independent thesis Advanced level (degree of Master (Two Years))Student thesis

By means of fuzzy set theory as well as Takagi-Sugeno and Mamdani fuzzy controller, this paper presents the investigation of a Resort Management System implemented by a combination of a T-S model and a Mamdani model. It demonstrates the procedure of the specific premise parameters identification and consequence parameters identification performed by regression knowledge in the T-S model, and the process of the fuzzification, the rule base creation and the defuzzification with COG technique in the Mamdani model. Therefore, an aggregation between T-S controller and Mamdani controller applied in the field of management by a novel angle is illustrated, which, as a result, devotes an improved management system that shares great convenience in the control process when combined with mathematics. Moreover, a modification of the conventional Takagi-Sugeno and Mamdani controller is demonstrated in conjunction with fuzzy operations t-norms and OWA by adjusting the -value, which is used in the calculation of final outputs in the T-S model and the computation of rule consequences in the Mamdani model. The algebraic intersection, bounded intersection as well as the -parameter t-norm are the t-norms which are going to be introduced. Besides, we have tested that t-norms generate the same alpha values when the membership degrees meet the boundary with the value of 1 or 0 while OWA can still yield a well-balanced result different from the one computing by minimum operation. Nevertheless both t-norms and OWA are able to shift the alpha-value in a well-adjusted way when the membership degrees lie in the interval [0,1]. A tendency has been shown that alpha-value tends to decrease by means of t-norms and OWA operations and consequently, the final outputs appear to be reduced.

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