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Industrial Embedded Systems - IES'2006

作者： Nilsson, Björn Bengtsson, Lars Bilstrup, Urban Wiberg, Per-Arne Svensson, Bertil Halmstad University Halmstad Sweden Department of Computer Science and Engineering Chalmers University of Technology Göteborg Sweden Free2move AB Halmstad Sweden

ISBN: (纸本)142440777X

The use of Radio Frequency Identification systems (RFID) is growing rapidly. Today, mostly "passive" RFID systems are used because no onboard energy source is needed on the transponders. However, "active" RFID with onboard power source gives a new range of opportunities not possible with passive systems. To obtain energy efficiency in an Active RFID system a protocol should be designed that is optimized with energy in mind. This paper describes the on-going work of defining and evaluating such a protocol. The protocol's performance in terms of energy efficiency, aggregated throughput, delay, and number of air collisions is evaluated and compared to that of the medium-access layer in 802.15.4 Zigbee, and also to a commercially available protocol from Free2move. ©2006 IEEE.

关键词： Energy efficiency

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Simple penalty-sensitive replacement policies for caches

Simple penalty-sensitive replacement policies for caches

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3rd Conference on Computing Frontiers 2006, CF '06

作者： Jeong, Jaeheon Stenström, Per Dubois, Michel Intel Hillsboro OR 97214 Department of Computer Science and Engineering Chalmers University of Technology Gothenburg Sweden Department of Electrical Engineering Systems University of Southern California Los Angeles CA 90089-2562

ISBN: (纸本)1595933026

Classic cache replacement policies assume that miss costs are uniform. However, the correlation between miss rate and cache performance is not as straightforward as it used to be. Ultimately, the true cost measure of a miss should be the penalty, i.e. the actual processing bandwidth lost because of the miss. It is known that, contrary to loads, the penalty of stores is mostly hidden in modern processors. To take advantage of this observation, we propose simple schemes to replace load misses by store misses. We extend classic replacement algorithms such as LRU (Least Recently Used) and PLRU (Partial LRU) to reduce the aggregate miss penalty instead of the miss count. One key issue is to predict the next access type to a block, so that higher replacement priority is given to blocks that will be accessed next with a store. We introduce and evaluate various prediction schemes based on instructions, and broadly inspired from branch predictors. To guide the design we run extensive trace-driven simulations on eight Spec95 benchmarks with a wide range of cache configurations and observe that our simple penalty-sensitive policies yield positive load miss improvements over classic algorithms across most the benchmarks and cache configurations. In some cases the improvements are very large. Copyright 2006 ACM.

关键词： Cache memory

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Inferring evolution in bacteria using Markov chains and genomic signatures

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Doktorsavhandlingar vid chalmers Tekniska Hogskola 2006年第2506期 1-46页

作者： Dalevi, Daniel Department of Computer Science and Engineering Chalmers University of Technology Göteborg University SE-412 96 Göteborg Sweden Department of Computer Science and Engineering Chalmers University of Technology Göteborg University

This thesis concerns the development of methods and models in evolutionary molecular biology. The techniques are also applicable to other similar biological problems. The first contribution is a novel classifier using fixed and variable length Markov chains that can discriminate between bacterial DNA of different species. The classifier assumes that the composition of oligomers, DNA words, is species-specific and represents global features of the species, a so called genomic signature. The direct applications of such a classifier are: identification of horizontal gene transfer and binning of metagenomic data. The former has been the primary focus as it is one of the central processes in the evolution of bacteria. We suggest a new method for locking the number of parameters in a variable length Markov model and propose a method for rejecting false candidates of horizontal gene transfer events. The second contribution is a novel estimator for finding the prediction suffix tree of a variable length Markov chain. This new estimator is highly efficient in finding the correct state-space and we show that it compares favorably to a popular estimator in terms of the predictive likelihood. The third contribution is to the analysis of gene order rearrangements in bacteria. We recapitulate previous results on expected distances and derive new ones for cases that have recently gained support in the literature, such as symmetrical and short reversals. We also describe new categories of gene order patterns and show how these can be explained with models using short, symmetric and uniformly distributed transpositions and reversals. The forth contribution is a part of the Greengenes project which is a chimera free database of 16S rDNA sequences.

关键词： Bacteriology

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A first order extension of Stålmarck's method

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Doktorsavhandlingar vid chalmers Tekniska Hogskola 2006年第2451期 1-140页

作者： Björk, Magnus Department of Computer Science and Engineering Chalmers University of Technology Göteborg University Göteborg SE-412 06 Sweden Department of Computer Science and Engineering Chalmers University of Technology Göteborg Universit

Stålmarck's method is a an algorithm that decides validity of formulae in prepositional logic. It resembles many tableaux method, but uses a special branch-and-merge-rule, called the dilemma rule. The dilemma rule creates two branches, where a formula (called the dilemma formula) is assumed to be false in one branch and true in the other one. If neither of the branches turns out to be contradictory, then the branches are merged into one branch again, retaining the common consequences of the two branches. We present a first order version of Stålmarck's method. When branches are merged in first order logic, variables occurring in the respective branches are unified, to retain as much information as possible. We show that variables introduced in dilemma formulae must be treated rigidly in the branches of the dilemma where they were introduced, but that they are universal during and after the merge. Thus, the dilemma rule can be used to introduce lemmas with universal variables. We also present a proof procedure that searches for shallow dilemma proofs. It begins by searching for proofs not including the dilemma rule, then extends the search with non-nested dilemmas. After that, proofs with at most two simultaneously open dilemmas are found, then with three, and so on. The proof procedure does not substitute rigid variables destructively;instead it explores an instance of the current dilemma, after the branches have been merged. This is done to preserve as many generalized conclusions as possible, and to be able to find new dilemma formulae. We show that the calculus and proof procedure are sound and complete. We present encouraging benchmarks for the automated theorem prover Dilemma, that is based on the method.

关键词： Algorithms

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Reverse conversion architectures for signed-digit residue number systems

Reverse conversion architectures for signed-digit residue nu...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： A. Persson L. Bengtsson Department of Computer Science and Engineering Computer Engineering Division Chalmers University of Technology Sweden

This paper presents circuits for conversion from radix-2 signed-digit residue numbers to binary form. Four reverse converters for combined RNS/SD number systems based on different moduli sets are presented. Implementations are compared with respect to timing, area and area-delay products. Finite impulse response (FIR) filters are used as reference designs in order to evaluate the performance of RNS/SD processing in a typical DSP block using the suggested moduli sets

关键词： Arithmetic Circuits Finite impulse response filter Dynamic range computer architecture computer science Timing Concurrent computing High performance computing Digital signal processing

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Reduction of Energy Consumption in Processors by Early Detection and Bypassing of Trivial Operations

Reduction of Energy Consumption in Processors by Early Detec...

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International Conference on Embedded computer Systems: Architectures, Modeling and Simulation (IC-SAMOS)

作者： Md. Mafijul Islam Per Stenstrom Department of Computer Science and Engineering Chalmers University of Technology Sweden

Previous research has established that trivial operations, i.e., instructions whose outcome can be trivially inferred from the operands, e.g. addition of zero, account for a quite significant portion of the dynamically executed instructions. By detecting them early and removing them from the pipeline, it is possible to reduce the energy consumption. This paper first presents a new classification of trivial operations in which especially such trivial operations that can be detected early, i.e. at the decode stage, in the pipeline are identified. Our analysis shows that on average as many as 10% of all executed instructions are of this kind across 12 applications from SPEC2000. We find that a majority (indeed 89%) of them are identity-trivial in which at least one of the operands is the identity element - zero or one. By detecting them early, one can bypass their execution and eliminate register accesses if the processor uses a logical/physical register remapping unit. We find that as many as 75% of all trivial operations can be detected and eliminated at the decode stage because the identity element is available that often. With such support, we find that the energy consumption in the functional units, the result bus, the instruction window infrastructure, and the register file can be reduced by 13%, 9%, 27%, and 26%, respectively yielding 18% reduction of the energy in the core pipeline

关键词： Energy consumption Registers Pipelines Decoding computer aided instruction computer science Power engineering and energy Performance gain Program processors Optimizing compilers

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Framework for structuring information for environmental management of industrial systems

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Doktorsavhandlingar vid chalmers Tekniska Hogskola 2006年第2447期 1-112页

作者： Carlson, Raul Department of Computer Science and Engineering Chalmers University of Technology Göteborg University SE - 412 96 Göteborg Sweden Department of Computer Science and Engineering Research Group: Industrial Environmental Informatics Chalmers University of Technology

This thesis addresses information structuring for reducing cost, facilitate understandability, increase relevance and improve quality of environmental information. The research is based in experience, practical results and syntheses from three different but related research and development projects conducted between 1994 and 2004. The projects have involved different industrial and academic partners in Sweden and other EU countries, and have also had active interactions with the international standardisation effort within ISO (International Organization for Standardization). To actively take environmental responsibility for designing, producing or purchasing a product it is necessary to have information about consequences from the decisions. Environmental impacts from industrial products, activities and systems may be gradual, diffuse, long term and complex. They originate not only from extraction of natural resources, emissions and waste generation, but also from transportation, storage, use and end of life phases. The complexity makes it difficult to foresee the total environmental impact from industrial systems. There are methods and tools available to environmentally assess environmental performance of the life cycle of products and services, but it is still difficult to acquire the information needed to perform the assessment. It is also difficult to present the results from the assessments in a clear and logic way. Hence, it is difficult for consumers or professional decision makers to take into regard environmental consequences from their decisions. Due to the increasing global population and accelerating economies of the developing worlds, it is probable that the needs for more effective and efficient information handling for different global responsibility issues will increase. The material presented concerns solving problems of environmental management of different industrial systems, using techniques for information structuring. The techniques include a c

关键词： Management information systems

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Securing interaction between threads and the scheduler

Securing interaction between threads and the scheduler

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computer Security Foundations Workshop

作者： A. Russo A. Sabelfeld Department of Computer Science and Engineering Chalmers University of Technology Goteborg Sweden

The problem of information flow in multithreaded programs remains an important open challenge. Existing approaches to specifying and enforcing information flow security often suffer from over-restrictiveness, relying on non-standard semantics, lack of compositionality, inability to handle dynamic threads, scheduler dependence, and efficiency overhead for code that results from security-enforcing transformations. This paper suggests a remedy for some of these shortcomings by developing a novel treatment of the interaction between threads and the scheduler. As a result, we present a permissive noninterference-like security specification and a compositional security type system that provably enforces this specification. The type system guarantees security for a wide class of schedulers and provides a flexible and efficiency-friendly treatment of dynamic threads

关键词： Yarn Information security Data security Processor scheduling Multithreading Dynamic scheduling computer security computer science Pressing Concurrent computing

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Towards an integrated conceptual model of security and dependability

Towards an integrated conceptual model of security and depen...

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International Conference on Availability, Reliability and Security, ARES

作者： E. Jonsson Department of Computer Science and Engineering Chalmers University of Technology Goteborg Sweden

It is now commonly accepted that security and dependability largely represent two different aspects of an overall meta-concept that reflects the trust that we put in a computer system. There exist a large number of models of security and dependability with various definitions and terminology. This position paper suggests a high-level conceptual model that is aimed to give a novel approach to the area. The model defines security and dependability characteristics in terms of a system's interaction with its environment via the system boundaries and attempts to clarify the relation between malicious environmental influence, e.g. attacks, and the service delivered by the system. The model is intended to help reasoning about security and dependability and to provide an overall means for finding and applying fundamental defense mechanisms. Since the model is high-level and conceptual it must be interpreted into each specific sub-area of security/dependability to be practically useful.

关键词： Availability Data security Information security computer security Maintenance Software safety computer science Reliability engineering Terminology Writing

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Change Impact Analysis for Generic Libraries

Change Impact Analysis for Generic Libraries

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International Conference on Software Maintenance (ICSM)

作者： Marcin Zalewski Sibylle Schupp Department of Computer Science and Engineering Chalmers University of Technology Goteborg Sweden

Since the standard template library (STL), generic libraries in C++ rely on concepts to precisely specify the requirements of generic algorithms (function templates) on their parameters (template arguments). Modifying the definition of a concept even slightly, can have a potentially large impact on the (interfaces of the) entire library. In particular the non-local effects of a change, however, make its impact difficult to determine by hand. In this paper we propose a conceptual change impact analysis (CCIA), which determines the impact of changes of the conceptual specification of a generic library. The analysis is organized in a pipe-and-filter manner, where the first stage finds any kind of impact, the second stage various specific kinds of impact. Both stages describe reachability algorithms, which operate on a conceptual dependence graph. In a case study, we apply CCIA to a new proposal for STL iterator concepts, which is under review by the C++ standardization committee. The analysis shows a number of unexpected incompatibilities and, for certain STL algorithms, a loss of genericity

关键词： Libraries Algorithm design and analysis Concrete Containers Filters Proposals Standardization computer science Taxonomy Object oriented programming

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