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Invariant based programming: basic approach and teaching experiences

FORMAL ASPECTS OF COMPUTING 2009年第3期21卷 227-244页

作者： Back, Ralph-Johan Abo Akad Univ Turku Finland

program verification is usually done by adding specifications and invariants to the program and then proving that the verification conditions are all true. This makes program verification an alternative to or a complement to testing. We describe here another approach to program construction, which we refer to as invariant based programming, where we start by formulating the specifications and the internal loop invariants for the program, before we write the program code itself. The correctness of the code is then easy to check at the same time as one is constructing it. In this approach, program verification becomes a complement to coding rather than to testing. The purpose is to produce programs and software that are correct by construction. We present a new kind of diagrams, nested invariant diagrams, where program specifications and invariants (rather than the control) provide the main organizing structure. Nesting of invariants provide an extension hierarchy that allows us to express the invariants in a very compact manner. We have studied the feasibility of formulating specifications and loop invariants before the code itself has been written in a number of case studies. Our experience is that a systematic use of figures, in combination with a rough idea of the intended behavior of the algorithm, makes it rather straightforward to formulate the invariants needed for the program, to construct the code around these invariants and to check that the resulting program is indeed correct. We describe our experiences from using invariant based programming in practice, both from teaching programmers how to construct programs that they prove correct themselves, and from teaching invariant based programming for CS students in class.

关键词： programming Problem Formal Method Teaching Experience Termination Function program code

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A high-efficient tables memory access saving algorithm for CAVLC decoding

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SIGNAL IMAGE AND VIDEO PROCESSING 2015年第8期9卷 1805-1814页

作者： Wang, Jianhua Cheng, Lianglun Liu, Jun Sun, YunLong Guangdong Univ Technol Fac Automat Guangzhou 510006 Guangdong Peoples R China Guangdong Univ Technol Fac Informat Engn Guangzhou 510006 Guangdong Peoples R China

Frequent table look-up can result in high memory access, and high memory access can cause increased power consumption in CAVLC decoding. Aiming to solve the problem of high table memory access during the process of CAVLC decoding for H.264/AVC due to frequent table look-up, thereby reducing the power consumption, a high-efficient table memory access saving algorithm is presented in this paper. The contribution of the proposed scheme is that we use program code to instead of the conventional table look-up method that requires a lot of memory access. In our scheme, we use program code to realize fully the expression of all the UVLT (Unstructured Variable Length Tables) in CAVLC decoding, as a result, all the decoded codewords in UVLT can be obtained easily through a program execution way instead of sequential table look-up. which can save a lot of memory access and power consumption due to without looking up UVLT in CAVLC decoding, The simulation results show that our proposed scheme can save 100 % memory access of table look-up for CAVLC decoding compared with TLSS method due to the use of program code, thereby saving much power consumption, without degrading video quality.

关键词： CAVLC decoding Table look-up Memory access program code

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Computer aided data acquisition tool for high-throughput phenotyping of plant populations

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PLANT METHODS 2009年第1期5卷 1-10页

作者： Vankadavath, Raju Naik Hussain, Appibhai Jakir Bodanapu, Reddaiah Kharshiing, Eros Basha, Pinjari Osman Gupta, Soni Sreelakshmi, Yellamaraju Sharma, Rameshwar Univ Hyderabad Sch Life Sci Hyderabad 500046 Andhra Pradesh India JK AgriGenet Hyderabad 500016 Andhra Pradesh India St Edmunds Coll Dept Bot Shillong 793003 Meghalaya India Yogi Vemana Univ Dept Genet & Genom Kadapa 516003 India

Background: The data generated during a course of a biological experiment/study can be sometimes be massive and its management becomes quite critical for the success of the investigation undertaken. The accumulation and analysis of such large datasets often becomes tedious for biologists and lab technicians. Most of the current phenotype data acquisition management systems do not cater to the specialized needs of large-scale data analysis. The successful application of genomic tools/strategies to introduce desired traits in plants requires extensive and precise phenotyping of plant populations or gene bank material, thus necessitating an efficient data acquisition system. Results: Here we describe newly developed software "PHENOME" for high-throughput phenotyping, which allows researchers to accumulate, categorize, and manage large volume of phenotypic data. In this study, a large number of individual tomato plants were phenotyped with the "PHENOME" application using a Personal Digital Assistant (PDA) with built-in barcode scanner in concert with customized database specific for handling large populations. Conclusion: The phenotyping of large population of plants both in the laboratory and in the field is very efficiently managed using PDA. The data is transferred to a specialized database(s) where it can be further analyzed and catalogued. The "PHENOME" aids collection and analysis of data obtained in large-scale mutagenesis, assessing quantitative trait loci (QTLs), raising mapping population, sampling of several individuals in one or more ecological niches etc.

关键词： Personal Digital Assistant Mobile Computing Touch Screen program code Reverse Genetic

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Automated symbolic calculations in nonequilibrium thermodynamics

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COMPUTER PHYSICS COMMUNICATIONS 2010年第12期181卷 2149-2157页

作者： Kroeger, Martin Huetter, Markus ETH Dept Mat CH-8093 Zurich Switzerland

We cast the Jacobi identity for continuous fields into a local form which eliminates the need to perform any partial integration to the expense of performing variational derivatives. This allows us to test the Jacobi identity definitely and efficiently and to provide equations between different components defining a potential Poisson bracket. We provide a simple Mathematica(TM) notebook which allows to perform this task conveniently, and which offers some additional functionalities of use within the framework of nonequilibrium thermodynamics: reversible equations of change for fields, and the conservation of entropy during the reversible dynamics.

关键词： Jacobi identity Reversible dynamics Time-structure invariance Degeneracy conditions program code Poisson bracket

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Antifungal efficiency assessment of the TiO₂ coating on facade paints

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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH 2014年第19期21卷 11228-11237页

作者： Vucetic, Snezana B. Rudic, Ognjen Lj. Markov, Sinisa L. Bera, Oskar J. Vidakovic, Ana M. Skapin, Andrijana S. Sever Ranogajec, Jonjaua G. Univ Novi Sad Fac Technol Novi Sad 21000 Serbia Slovenian Natl Bldg & Civil Engn Inst Ljubljana 1000 Slovenia

The work studies the photocatalytic activity and the antifungal efficiency of the TiO2/Zn-Al coatings placed on the target commercial facade paints. The photocatalytic active nanocomposite based on TiO2 and Zn-Al-layered double hydroxides (ZnAl-LDHs) was synthesized by a wet impregnation technique with 3 % w/w TiO2. The freshly prepared suspension was applied by spray technique on the surfaces of the white facade paints. The goal of the work was to develop a method that quickly quantifies the antifungal activity of the commercial facade paints with and without biocidal components covered with a photocatalytic coating. The essence of the proposed method is the monitoring of the fungal growth (artificial ageing conditions) and the quantification of its development (UV-A 0.13 mWcm(-2)) on the facade paint surfaces. A special fungus nutrient (potato dextrose agar (PDA)) was inoculated with the spores of the Aspergillus niger ATCC 6275, and the test samples (facade paints with and without photocatalytic coating) were placed on the inoculated nutrient in the petri dishes. The images of the fungal growth on the samples of the facade paints, during a period of 5 days, were imported into Matlab R2012a where they were converted to binary images (BW), based on the adequate threshold. The percentage of the surface coverage was calculated by applying the specifically written program code which determines the ratio of the black and white pixels. The black pixels correspond to the surface covered with hyphae and mycelia of the fungus.

关键词： Antifungal efficiency Photocatalytic coating Coating durability Porous substrates Facade paints program code

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Lex Informatica: Information Technology as a Legal Tool 6th

Lex Informatica: Information Technology as a Legal Tool

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6th International Conference on Digital Transformation and Global Society (DTGS)

作者： Amelin, Roman Channov, Sergey Lipatov, Eduard Natl Res Saratov State Univ 83 Astrakhanskaya St Saratov 410012 Russia Russian President Acad Natl Econ & Publ Adm 23-25 Sobornaya St Saratov 410031 Russia

ISBN: (纸本)9783030937157;9783030937140

In the era of the fourth technological revolution, the implementation of social relations depends on information technology and software systems. The program code that controls the operation of these systems begins to play the role of a regulator of social relations, since it de facto sets the boundaries of capabilities and imposes requirements on user behavior. The paper opened a discussion about what conditions are important for the program code to receive scientific recognition as a source of law. Three features are proposed to be considered necessary conditions. First, the program code must have an impact on social relations. Secondly, he must establish special rules for the participants in these relations, which are absent in legal acts, moreover, these rules de facto receive the status of mandatory if the information system (computer program, other tool) is the only way to exercise certain rights and/or responsibilities of the subject. Finally, users and other actors should accept these rules as a given, and consider opposition to them as an undesirable exception. A separate and very important issue is the attitude of the state - it must at least recognize and support the rules laid down in the code as the natural order of things in the corresponding social relations (if the state takes on the role of guarantor of such rules, for example, obliging the subjects of the right to use certain software, then the program code de facto begins to play the role of a source of law).

关键词： Legal norms program code Source of law Lex informatica State information systems Digital transformation code legitimacy

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Executable visual contracts

Executable visual contracts

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IEEE Symposium on Visual Languages and Human-Centric Computing

作者： Lohmann, M Sauer, S Engels, G Univ Paderborn Dept Comp Sci D-33098 Paderborn Germany

ISBN: (纸本)0769524435

Design by Contract (DbC) is widely acknowledged to be a powerful technique for creating reliable software. DbC allows developers to specify the behavior of an operation precisely by pre- and post-conditions. Existing DbC approaches predominantly use textual representations of contracts to annotate the actual program code with assertions. In the Unified Modeling Language (UML), the textual Object Constraint Language (OCL) supports the specification of pre- and post-conditions by constraining the model elements that occur in UML diagrams. However textual specifications in OCL can become complex and cumbersome, especially for software developers who art, typically not used to OCL. In this paper we propose to specify the preand post-conditions of an operation visually by a pair of UML object diagrams (visual contract). We define a mapping of visual contracts into Java classes that are annotated with behavioral interface specifications in the Java Modeling Language (JML). The mapping supports testing the correctness of the implementation against the specification using JML tools, which include a runtime assertion checker Thus we make the visual contracts executable.

关键词： Java Unified Modeling Language formal specification formal verification object-oriented programming software reliability visual programming Java classes Java modeling language UML object diagrams behavior specification behavioral interface specification UML visual programming contract object oriented programming Software reliability Formal verification Specifications Formal specifications interface specification Visualization program code

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Smart Contracts: Security Patterns in the Ethereum Ecosystem and Solidity 1

Smart Contracts: Security Patterns in the Ethereum Ecosystem...

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IEEE 1st International Workshop on Blockchain Oriented Software Engineering (IWBOSE)

作者： Woehrer, Maximilian Zdun, Uwe Univ Vienna Fac Comp Sci Wahringerstr 29 A-1090 Vienna Austria

ISBN: (纸本)9781538659861

Smart contracts that build up on blockchain technologies are receiving great attention in new business applications and the scientific community, because they allow untrusted parties to manifest contract terms in program code and thus eliminate the need for a trusted third party. The creation process of writing well performing and secure contracts in Ethereum, which is today's most prominent smart contract platform, is a difficult task. Research on this topic has only recently started in industry and science. Based on an analysis of collected data with Grounded Theory techniques, we have elaborated several common security patterns, which we describe in detail on the basis of Solidity, the dominating programming language for Ethereum. The presented patterns describe solutions to typical security issues and can be applied by Solidity developers to mitigate typical attack scenarios.

关键词： Contracts Cryptography programming Virtual machining Writing contract Soundness virtual machines Writing cryptography programming virtual machining program code

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The Analysis of Microprocessor Instruction Cycle

The Analysis of Microprocessor Instruction Cycle

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18th Conference on Computer Networks (CN 2011)

作者： Kwiecien, Andrzej Mackowski, Michal Skoroniak, Krzysztof Silesian Tech Univ Inst Comp Sci PL-44100 Gliwice Poland

ISBN: (纸本)9783642217708

Each microcontroller realizing the code saved in a program memory emits electromagnetic disturbances, both conducted that propagate through lines connected to the processor and radiated in the form of electromagnetic field. All of these undesirable signals emitted by the processor can be measured, received and interpreted by the appropriate methods. However, this subject requires a precise measurement and understanding of processes occurring inside the microprocessor during realization of the sequential instructions. The presented results of the influence of parameters such as data bus state, instruction argument, the result of operation on the voltage waveform on the power supply lines of microprocessor, enable to understand the processes occurring during the realization of following instructions by microprocessor unit.

关键词： reverse engineering program code microcontroller conducted emission electromagnetic disturbances electromagnetic interference

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Runtime execution monitoring (REM) to detect and prevent malicious code execution

Runtime execution monitoring (REM) to detect and prevent mal...

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IEEE International Conference on Computer Design

作者： Fiskiran, AM Lee, RB Princeton Univ Dept Elect Engn Princeton NJ 08544 USA

ISBN: (纸本)0769522319

Many computer security threats involve execution of unauthorized foreign code on the victim computer. Viruses, network and email worms, Trojan horses, backdoor programs used in Denial of Service attacks are a few examples. In this paper, we present an architectural technique, which we call Runtime Execution Monitoring (REM), to detect program flow anomalies associated with such malicious code. The key idea in REM is the verification of program code at the hash block (similar to a basic block) level. This is achieved by pre-computing keyed hashes (HMACs) for each hash block during program installation, and then verifying these values during program execution. By verifying program code integrity at the hash block level, REM can monitor instructions whose behavior is typically exploited by malicious code, such as branch, call, return instructions. Performance degradation with REM averages 6.4% on our benchmark programs, which can be reduced to under 5% by increasing the size of the L1 instruction cache.

关键词： message authentication program verification memory architecture cache storage file organisation runtime execution monitoring malicious code execution computer security unauthorized foreign code victim computer program flow anomalies keyed message authentication code program code verification instruction cache memory file organisation Computer Security message authentication cache storage Memory architecture Spyware Legal Executions block level hashing program code

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