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268 Uppsatser om Compression algorithm - Sida 16 av 18

Heuristisk profilbaserad optimering av instruktionscache i en online Just-In-Time kompilator

This master?s thesis examines the possibility to heuristically optimise instruction cache performance in a Just-In-Time (JIT) compiler. Programs that do not fit inside the cache all at once may suffer from cache misses as a result of frequently executed code segments competing for the same cache lines. A new heuristic algorithm LHCPA was created to place frequently executed code segments to avoid cache conflicts between them, reducing the overall cache misses and reducing the performance bottlenecks. Set-associative caches are taken into consideration and not only direct mapped caches.

Automatisk query expansion: en komparativ studie av olika strategier för termklustring baserade på lokal analys

Automatic query expansion has long been studied in information retrieval research as a technique that deals with the fundamental issue of word mismatch between query and document. The purpose of this thesis is to compare the retrieval effectiveness of different strategies for automatic query expansion. The strategies are based on local analysis of the corpus and use statistical information from the local document set to extract terms that suppose to adapt themselves to each individual search and therefore appear to be searchonyms to the index terms. The strategies compared are: association clusters, metric cluster and scalar cluster. Baseline queries of 24 topics are expanded using terms from the different clusters and searches are made.

Direct-EGR tillämpat på HCCI

The Homogeneous Charge Compression Ignition (HCCI) engine is promising in terms of lowNOx, low particulates and high efficiency. Due to its homogeneous charge, where thecombustion starts almost simultaneously from a number of points in the combustion chamber,only lean mixtures are possible to burn because of the resulting rapid combustion, which is muchfaster than the combustion in an SI-engine or a diesel engine. When richer mixtures are used thecombustion will start earlier and also be more violent.To phase the combustion later and lower the combustion speed, external cooled EGR can beused. The EGR-system used in this thesis uses a divided exhaust channel where one channel andits corresponding valve are used only for transporting EGR back to the intake system.Consequently the EGR-valve is connected to the intake pressure. This system is called Direct-EGR (D-EGR).Engine tests verified that the CA50 indeed is phased later when cooled EGR is used.

Manuell arytmitolkning och defibrillering prehospitalt för att minska avbrott i bröstkompressioner

Abstract Background Todays guidelines for advanced CPR emphasize chest compressions with good quality and early defibrillation. Prehospital CPR performed by ambulance crew, an automated external defibrillator (AED) is used. The AED analyzes the heart rhythm and the performer is following the advice to chock the heart or not, given by the AED. During on-going CPR there are sequences when no chest compression is performed known as hands-off time. Hands-off time includes the time for the AED to analyze the heart rhythm and the time when advice is given to the crew.

Rekursiv greyboxidentifiering av drivsystem i industrirobot.

In modern industrial robots the components in the transmission contain nonlinearities. These nonlinearities need to be to estimated either for better control or to use the parameters for diagnosis of the system. There is a lot of work done within system identification and mainly within the field of iterative parameter estimation.This thesis considers recursive grey-box identification for a nonlinear model of the transmission in an industrial robot. The nonlinearities that are identified are friction, spring stiffnes, hysteresis and backlash. These nonlinearities are a part of the models that are presented in this thesis.

Hur eller Varför? : Kunskap i sociokulturellt eller existentialistiskt perspektiv? En kritisk betraktelse

This essay set out to propose a problematic interpretation of the socio-cultural perspective on learning. Its purpose is to show how the socio-cultural perspective on learning defines the concept of knowledge in an incomplete way. The aim becomes then that of giving a more comprehensive description of this concept, and, to this end, to construct a new, broader pedagogic discourse. The investigation starts with a deconstructive analysis of Roger Säljö?s socio-cultural text in order to point out the incompleteness of the concept of knowledge.

Utveckling och dimensionering av en lastupptagande provningsram

ÅF Test Center in Borlänge had a need to expand their capacity for compressive and tensile strength tests. They wanted to do this by using a hydraulic cylinder, which they already possessed, to apply the force with. This required a load receiving structure. The aim of this work was to design and dimensioning a test bench for a cylinder marked NIKE 300 tons. The work would result in a completed design proposal on a test bench which could manage to run the compressive and tensile strength tests of up to 3000 kN.

Platt Hierarki : Metoder för omvandling av relationsdata till hierarkisk data

The relational database model was defined in the 1970?s and is the dominating database type today.  The main difference between data from a relational database and a hierarchical data structure is that the relational database stores records in tables. The records have no particular order, but can include links in terms of relationships with other records. A hierarchical structure organizes data in the form of a tree structure  and  can for an example be found in organizational structures in which different levels involves different responsibilities. If the data stored in a relational database is to be presented in a hierarchically, a conversion of the data structure is required. The intention of this paper is to describe how such a conversion can be performed.  To investigate the conversion methods, case studies has been conducted on the basis of a specific organization?s hierarchical structure.

Känsloigenkänning i form av ansiktsuttryck med Kinect

Facial expressions are a part of our body language that helps us to clarify the verbal communication between humans. We use our facial expressions every day, both consciously and unconsciously, to express emotions and attitudes depending on the situation. The hypothesis of the study is: Given a facial expression, how well can Microsoft Kinect, as an input method, determine a person?s feelings with the two algorithms Naive Bayes and Sequential Minimal Optimization? The feelings are limited to happy, sad, surprised and disgusted. With the help of Kinect, a person?s facial data, both coordinates of the face and parameterized data, were saved and used for machine learning.

Generationsskräpsamling med explicit kontroll av hårdvarucache

This report evaluates whether an interpreted high-level garbage collected language has enough information about its memory behaviour to make better cache decisions than modern general CPU hardware.With a generational garbage collector, depending on promotion algorithm and generation size, around 90% of all objects never leave the first generation. This report is based on the hypothesis that, because of the low promotion rate, accesses to higher generations are sufficiently rare not to benefit from caching.To test this hypothesis, we built an operating system with a Scheme interpreter in kernel mode, where the interpreter controls the cache. Generic x86 PC hardware was used, since it allows fine-grained control of cache decisions.Measurements of execution time in this interpreter show that disabling the cache for generations higher than the first does not give any performance gain, but rather a performance loss of up to 50%.We conclude that this interpreter design is not an improvement, but cannot conclude that the hypothesis is false in general. We suggest building a better CPU simulator to gather more data from which to make better caching decisions, moving internal interpreter data structures into the garbage collected heap and modifying the hardware to allow control in the currently rigid dimension of where data is cached---for example separate control of instruction and data caches and separate data caches for different areas of memory..

CFD simulering av en fyrtakts Otto motorcykel motor

This thesis deals with the numerical 3D simulation of a four stroke, spark-ignited, internalcombustion engine, which is mounted on a high performance motorcycle. The work, carried outin collaboration with Politecnico di Milano and MV Agusta, focuses on the simulation of theintake, compression and expansion stroke, including combustion simulation, using an opensource CFD code.Simulation of internal combustion engines offers a great challenge in the field of CFD research.Moving boundaries of the solution domain, caused by the motion of the piston and valves, leadsto deformation of the computational grid, with decreasing quality of the solution as result. Basedon this, a previously developed mesh motion strategy was employed where a number of meshesare used to cover the whole simulation cycle. Within each mesh interval the internal cell pointsof the mesh are moved to account for the boundary motion of the piston and valves. This strategywas previously applied to simplified geometries as well as real engine geometries.

HDR och Tone mapping i automatiserade tullsystem

This report is about how HDR (HighDynamicRange) can be created and used in combination with Tone mapping. This work has been carried out together with Kapsch TrafficCom AB in Jönköping.The objective of this project is to:Evaluate and investigate the effects given to pictures by HDR and tone mapping.Evaluate if the technology may lead to improvements in Kapsch?s systems.To construct a program which is able to handle some form of tone mapping or HDR-algorithm.These questions will be answered in this report:What kind of effects has HDR and tone mapping-algorithms on pictures?Can the HDR-technology give better data in Kapsch?s systems?The research method used in this report is called action research. This means the authors has investigated the technology by reading different documentations and by testing different algorithms to see what kind of result they give. The report describes some of the tests made to see if the technology is appropriate in Kapsch?s system.There is two smaller reports made by the authors which documenting some of the work.The first report describes the work with different settings for a camera to create pictures with HDR-quality.

Det kliniska användandet av Sacroilica-ledstester av sjukgymnaster i primärvården inom landstingen i Sverige: En randomiserad enkätstudie.

Livstidsprevalensen för ländryggsmärta är cirka 80%. Av dessa anses 13% ha sitt ursprung i Sacroiliaca-lederna. Vanliga uppkomstorsaker för SI-ledsproblematik är graviditet, feltramp, fallolyckor, sittande på ena sidan eller halkolyckor. SI-ledstester syftar till att påvisa ökad/minskad ledrörlighet eller provocera smärta. Forskning talar för användandet av smärtprovokationstester, framför allt ?thigh thrust test? och ?compression test? samt användandet av minst 3 positiva tester för diagnostik.

Upplagstryck för träbalkar enligt Eurokod 5 - Problematik och förstärkningsåtgärder

När Eurokod 5, standarden för dimensionering av träkonstruktioner, infördes i Sverige sågjordes det även en sänkning av hållfasthetsvärden för trä vid tryck vinkelrätt fibrerna.Tidigare kapacitet på 8 MPa för limträklass L40 var nu för högt, och den av SverigesTekniska Forskningsinstitut (SP) reviderade CE L40c fick en kapacitet på 2,7 MPa. Ettproblem i och med detta blev att byggnader som är konstruerade och uppförda enligtBoverkets föreskrifter inte längre kan utformas på samma sätt sedan Eurokodernasinförande. Syftet med arbetet blev därför att:? Ta reda på varför sänkningen skedde? Ta fram några räkneexempel på hur man kan åtgärda för låg kapacitet vid tryckvinkelrätt fibrernaLitteraturstudien som ligger till grund för arbetet visar på att sänkningen skedde på grund avatt Eurokodernas provmetod för bestämning av hållfastheten skiljer sig från den metod somBoverket använt. Den stora skillnaden ligger i att Eurokoderna inte utnyttjar lastspridning iträ, där lasten kan spridas från en träfiber till en annan intilliggande och på så vis öka denfaktiska kapaciteten.

Söktjänster för akademiskt bruk: En utvärdering av Google och Argos med frågor från en akademisk ämnesdisciplin

The purpose of this MSc thesis is to examine the retrieval effectiveness of two Web search engines with queries from the academic discipline of Classical Studies. The two search engines are chosen to represent two different types Google as a broad general search engine and Argos as a specialised search engine for the subject of Classical Studies. The search engines are compared for precision among the first twenty results returned for thirty queries. In order to avoid bias in the study, the queries are based on real users' information needs. Due to the subjective character of the concept of relevance, the study is performed with five different experiments with five different definitions of relevance.

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