Sharif Digital Repository

Carbon nanotubes (CNTs) are promising candidates for high-resolution mass nanosensors owing to their unique vibrational behavior. The structural characteristic (e.g. defect type and density) and working temperature have a significant effect on the natural frequency of CNT-based sensors. Herein, a stochastic approach based on novel finite element and molecular mechanics simulations is implemented to model the effect of temperature and structural characteristics of single-wall CNTs including defects (vacancy defect with different densities) and chirality (zigzag and armchair) on their vibrational behavior. The results show that the vacancy defects exert a significant deterioration of the... 

Dealing with crosscutting requirements in software development usually makes the process more complex. Modeling and analyzing of these requirements in the software architecture facilitate detecting architectural risks early. Distributed systems have more complexity and so these facilities are much useful in development of such systems. Aspect oriented Architectural Description Languages(ADL) have emerged to represent solutions for discussed problems; nevertheless, imposing radical changes to existing architectural modeling methods is not easily acceptable by architects. Software architecture analysis methods, furthermore, intend to verify that the quality requirements have been addressed... 

A thermo-mechanical model has been developed for modeling of hot extrusion processes. Accordingly, an admissible velocity field was first proposed by means of stream function method and then, extrusion pressure as well as temperature variations within the metal and the die were predicted employing a combined upper bound and Petrov-Galerkin finite element analysis. In order to evaluate the model predictions, hot extrusion of AA6061-10%SiCp was considered under both isothermal and non-isothermal conditions and the predicted force-displacement diagrams under various extrusion conditions were compared with the experimental ones and reasonable consistency was found between the two sets of results... 

Purpose - The purpose of this paper is to propose a mathematical model to estimate required energy and temperature distribution during cold extrusion process. Design/methodology/approach - An admissible velocity field is generated based on stream function technique. Then, the required energy and the temperature distributions in the metal and the extrusion die are determined by a coupled upper bound-finite element analysis. Findings - To examine the proposed model, cold extrusion of AA6061-10%SiCp is considered and the predicted extrusion force-displacement diagrams in different reductions are compared with the experimental ones and reasonable agreement is observed. Furthermore, it... 

A numerical approach has been developed based on the stream function technique and the finite element analysis to predict required power and temperature rise in wire drawing processes. An admissible velocity field is first proposed using a stream function and then power consumption in the wire drawing is optimized to achieve sensible and unique deformation geometry. In addition, the finite element method together with axi-symmetric Petrov-Galerkin algorithm is coupled with the deformation model to assess the temperature distribution in both the deforming wire and the die during the process. The work hardening effects are also considered in the model both in the deformation zone and on the... 

Complexity of the software development process is often increased by actuality of crosscutting concerns in software requirements; moreover, Software security as a particular non-functional requirement of software systems is often addressed late in the software development process. Modeling and analyzing of these concerns and especially security in the software architecture facilitate detecting architectural vulnerabilities, decrease costs of the software maintenance, and reduce finding tangled and complex components in the ultimate design. Aspect oriented ADLs have emerged to overcome this problem; however, imposing radical changes to existing architectural modeling methods is not easily... 

In this work, the effect of the accumulative roll bonding (ARB) process on the microstructure, mechanical properties, and corrosion characteristics of AZ31 Mg alloy was investigated. First, the ARB process up to 3 cycles at 350 °C was applied to annealed AZ31 Mg alloy sheets. Then, all samples were characterized via microstructure observations, mechanical investigations, and also, electrochemical analyses, and immersion tests in simulated body fluid (SBF) solution. In addition, the L929 cell line was used to evaluate the cytotoxicity of the samples. The obtained results showed that after the third ARB cycle, the average grain size in the annealed sample decreased from ~ 14 to ~ 3 µm. Some... 

Existence of crosscutting concerns in software requirements often intensifies complexity of software development process. Modeling and analyzing of these concerns in the software architecture decrease possibility of finding tangled and complex components in the ultimate design. Aspect oriented ADLs have emerged to overcome this problem; however, imposing radical changes to existing architectural modeling methods is not easily acceptable by architects. In this paper, we present a method to enhance conventional software architecture description languages through utilization of aspect features with special focuses on non-functional requirements (NFRs). © 2007 IEEE  

In our previous work, we presented a Z-based formalism, called NZ, by which one can explicitly specify bounded, unbounded, erratic, angelic, demonic, loose, strict, singular, and plural nondeterminism. The NZ notation is mainly based on a new notion of operation schemas, called multi-schema. Since the operations of the Z schema calculus do not work on multi-schemas anymore, in this paper we augment NZ with a new set of schema calculus operations that can be applied on multi-schemas as well as ordinary operation schemas. To demonstrate the usability of the resulting formalism, we show how this formalism can assist to model game-like situations and concurrent systems as two well-known classes... 

Context: It is well-known that the use of formal methods in the software development process results in high-quality software products. Having specified the software requirements in a formal notation, the question is how they can be transformed into an implementation. There is typically a mismatch between the specification and the implementation, known as the specification-implementation gap. Objective: This paper introduces a set of translation functions to fill the specification-implementation gap in the domain of database applications. We only present the formal definition, not the implementation, of the translation functions. Method: We chose Z, SQL and Delphi languages to illustrate our... 

Test Driven Development (TDD), as a quality promotion approach, suffers from some shortages that discourage its usage. One of the most challenging shortcomings of TDD is the low level of granularity and abstraction. This may lead to production of software that is not acceptable by the end users. Additionally, exploiting of TDD is not applicable in the enterprise systems development. To overcome this defect, we have merged TDD with Model Based Testing (MBT) and suggested a framework named Model Based Test Driven Development (MBTDD). According to TDD, writing test cases comes before programming, and based on our improved method of TDD, modeling precedes writing test cases. To validate the... 

It is well known that the use of formal methods in the software development process results in a high-quality software product. However, since formal approaches are just reasoning mechanisms, they do not offer defined ordered steps and guidance for moving between them. Refinement is a technique for moving between specifications but it bears very little resemblance to the real process of software design. An automatic translator from a specification language to an executable code would be highly useful in maximizing the benefits of formal methods. In the domain of database applications, we propose a rule-based algorithm to translate software requirements written in Z specifications to... 

As requirements and environments become much more complex, the need for self-adaptive and self-healing software system grows. There are several existing works which present such systems by using different approaches. Using alternative solutions to provide a service or requirement is one of the most important approaches among existing works. In this paper an alternative-based approach for adding self-adaptive capabilities to software systems is proposed. In this approach a group of autonomic elements will be constructed based on different design or implementations that could be considered for a specific service or requirement. By using this approach, a highly adaptive software system could be... 

In this paper, we derive Z input/output data refinement rules, including forwards and backwards rules, for the case in which the retrieve schemas are total functions when viewed as relations from the concrete to abstract variables. In practice, the relation between the abstract and concrete variables is often functional. Therefore, the use of the functional input/output refinement rules will reduce the cost and duration of the software development because the proof of the consistency of the abstract and concrete specifications is more easily demonstrated  

Context: Generating test cases based on software input interface is a black-box testing technique that can be made more effective by using structured input models such as input grammars. Automatically generating grammar-based test inputs may lead to structurally valid but semantically invalid inputs that may be rejected in early semantic error checking phases of a system under test. Objective: This paper aims to introduce a method for specifying a grammar-based input model with the model's semantic constraints to be used in the generation of positive test inputs. It is also important that the method can generate effective test suites based on appropriate grammar-based coverage criteria.... 

Context Event-Driven Software (EDS) is a class of software whose behavior is driven by incoming events. Web and desktop applications that respond to user-initiated events on their Graphical User Interface (GUI), or embedded software responding to events and signals received from the equipment in its operating environment are examples of EDS. Testing EDS poses great challenges to software testers. One of these challenges is the need to generate a huge number of possible event sequences that could sufficiently cover the EDS's state space. Objective In this paper, we introduce a new six-stage testing procedure for event-driven web applications to overcome EDS testing challenges. Method The... 

JML is a behavioral interface specification language which has Java as its target implementation language. It combines the idea of using Java expressions from Eiffel language with the model-based approach to specify a program. Refinement calculus is a framework to produce executable code from a specification by preserving the correctness of programs. In this paper some constructs of JML concerning object creation, feature call, exceptional behavior and concurrency constructs are studied and some refinement rules are proposed to obtain an object oriented code in Java from a JML specification containig these constructs. The correctness of these rules is proved by weakest precondition predicate... 

In this paper, we introduce a refinement approach to develop probabilistic programs formally. To achieve this goal, we first present a way to specify probabilistic programs in a Z-based notation. We then use an existing method of translating Z into a refinement calculus to transform our Z-style specifications of probabilistic programs into specification statements of the refinement calculus. We finally add new laws to the refinement calculus helping us to refine the resulting specification statements into probabilistic choice constructs of a probabilistic imperative language. In this way, we will provide a completely formal way for developing probabilistic programs. ©2009 IEEE  

Service-Oriented Architecture (SOA) is a software design framework where distributed services are provided and used by applications over a network. By using this architecture new challenges appeared for software testing. Lack of access to the source code and runtime binding are examples of these challenges. Functional testing of services assures the quality of service-oriented applications. In this paper, we introduce a new 3-phase consumer and provider contract-based process for web service testing to overcome SOA testing challenges. Our proposed process, namely OTaaWS, consists of Test Automation, Test Execution and Test Management steps on the provider's side, which can be done on-demand.... 

Predictive mutation testing (PMT) is a technique to predict whether a mutant is killed, using machine learning approaches. Researchers have proposed various methods for PMT over the years. However, the impact of unreached mutants on PMT is not fully addressed. A mutant is unreached if the statement on which the mutant is generated is not executed by any test cases. We aim at showing that unreached mutants can inflate PMT results. Moreover, we propose an alternative approach to PMT, suggesting a different interpretation for PMT. To this end, we replicated the previous PMT research. We empirically evaluated the suggested approach on 654 Java projects provided by prior literature. Our results...