A Study On Automatic Software Quality And Reliability Anlaysis

In this thesis the study over the topic of analytical approaches for software quality and reliability assurance is presented. The focus of this research is on a specific set of techniques used for software reliability assessment called Risk Analysis. Numerous approaches are explored and different new techniques are proposed to generate the risk model of a software product. These techniques are evaluated and using the results of this evaluation a new risk model (Compound Risk Model) is proposed which is using the advantages of different classes of risk analysis techniques to generate a more precise and practical model to identify more risky components of a software product. Also a research on the topic of Automatic Bug-Fix using Genetic Programming is presented which can fix logical defects of a buggy code and evolve it to a bug-free code. Finally it is discussed that these approaches can be used as an automated tool in an integrated development environment to localize the defective components and debug them.

A Study On Automatic Software Quality And Reliability Anlaysis

In this thesis the study over the topic of analytical approaches for software quality and reliability assurance is presented. The focus of this research is on a specific set of techniques used for software reliability assessment called Risk Analysis. Numerous approaches are explored and different new techniques are proposed to generate the risk model of a software product. These techniques are evaluated and using the results of this evaluation a new risk model (Compound Risk Model) is proposed which is using the advantages of different classes of risk analysis techniques to generate a more precise and practical model to identify more risky components of a software product. Also a research on the topic of Automatic Bug-Fix using Genetic Programming is presented which can fix logical defects of a buggy code and evolve it to a bug-free code. Finally it is discussed that these approaches can be used as an automated tool in an integrated development environment to localize the defective components and debug them.

Mitigation of Short-Term Temporal Variations of Receiver Code Bias to Achieve Increased Success Rate of Ambiguity Resolution in PPP

Ambiguity resolution (AR) is critical for achieving a fast, high-precision solution in precise point positioning (PPP). In the standard uncombined PPP (S-UPPP) method, ionosphere-free code biases are superimposed by ambiguity and receiver clock offsets to be estimated. However, besides the time-constant part of the receiver code bias, the complex and time-varying term in receivers destroy the stability of ambiguities and degrade the performance of the UPPP AR. The variation of receiver code bias can be confirmed by the analysis in terms of ionospheric observables, code multipath (MP) of the Melbourne–Wübbena (MW) combination and the ionosphere-free combination. Therefore, the effect of receiver code biases should be rigorously mitigated. We introduce a modified UPPP (M-UPPP) method to reduce the effects of receiver code biases in ambiguities and to decouple the correlation between receiver clock parameters, code biases, and ambiguities parameters. An extra receiver code bias is set to isolate the code biases from ambiguities. The more stable ambiguities without code biases are expected to achieve a higher success rate of ambiguity resolution and a shortened convergence time. The variations of the receiver code biases, which are the unmodeled errors in measurement residuals of the S-UPPP method, can be estimated in the M-UPPP method. The maximum variation of the code biases is up to 16 ns within two-hour data. In the M-UPPP method, the averaged epoch residuals for code and phase measurements recover their zero-mean features. For the ambiguity-fixed solutions in the M-UPPP method, the convergence times are 14 and 43 min with 17.7% and 69.2% improvements compared to that in the S-UPPP method which are 17 and 90 min under the 68% and 95% confidence levels.

Optimal Prefix Free Codes with Partial Sorting

We describe an algorithm computing an optimal prefix free code for n unsorted positive weights in time within O ( n ( 1 + lg α ) ) ⊆ O ( n lg n ) , where the alternation α ∈ [ 1 . . n − 1 ] approximates the minimal amount of sorting required by the computation. This asymptotical complexity is within a constant factor of the optimal in the algebraic decision tree computational model, in the worst case over all instances of size n and alternation α . Such results refine the state of the art complexity of Θ ( n lg n ) in the worst case over instances of size n in the same computational model, a landmark in compression and coding since 1952. Beside the new analysis technique, such improvement is obtained by combining a new algorithm, inspired by van Leeuwen’s algorithm to compute optimal prefix free codes from sorted weights (known since 1976), with a relatively minor extension of Karp et al.’s deferred data structure to partially sort a multiset accordingly to the queries performed on it (known since 1988). Preliminary experimental results on text compression by words show α to be polynomially smaller than n, which suggests improvements by at most a constant multiplicative factor in the running time for such applications.

Free Code Sharing Web Platform with Intelligent Developer Suggestion Tool

Due to increase in demands for websites, faster deployment requirements and complex functionality requirements, developers face the need for a centralized code repository system to store repetitive codes and a suggestion tool to help them in solving the errors and warnings they face during development. The proposed system provides a centralized database for storing repetitive code segments, errors, warnings and solutions and also a code suggestion mechanism to provide suggestions to the developer during development. The system includes a code collection system to help the user to add the codes, errors and solutions to the centralized database and an analyzer system to fetch the web-page data, errors and warnings to analyze and provide appropriate suggestions to the developer. The proposed system focuses to reduce work and development time of developers by providing code suggestions during development and also facilitate effective code reusability.