COCOMO as a schedule prognosis and validation tool: a case study

This paper describes a case study in the use of the COCOMO cost estimation model as a tool to provide an independent prognosis and validation of the schedule of a software project at IBM UK Laboratories Ltd, Hursley. Clearly case studies have the danger of being anecdotal however software engineers often work in situations where sufficient historical data is not available to calibrate models to the local environment. It is often necessary for the software engineer to attempt to use such tools on individual projects to justify their further use. This case study describes how we began to use COCOMO and concentrates on some of the problems and benefits which were encountered when trying to use COCOMO in a live development environment.The paper begins by discussing some problems in mapping the COCOMO phases on to the IBM development process. The practical aspects of gathering the development parameters of the model are described and the results of the work are presented in comparison to a schedule assessment using other prognosis techniques and the planned schedule at other milestones in the project's history. Some difficulties experienced in interpreting the data output from the model are discussed. This is followed by a brief comparison with other schedule analysis techniques used in quality assurance. We hope this case study shows that despite the problems in trying to use models such as COCOMO there are significant benefits in helping the user understand what is required to use such tools more effectively to improve software development cost estimates in the future.     

Now the learning curve affects CASE tool adoption

Part of adopting an industrial process is to go through a learning curve that measures the rate at which the average unit cost of production decreases as the cumulative amount produced increases. It is argued that organizations buy integrated CASE tools only to leave them on the shelf because they misinterpret the learning curve and its effect on productivity. It is shown that learning-curve models can quantitatively document the productivity effect of integrated CASE tools by factoring out the learning costs so that managers can use model results to estimate future projects with greater accuracy. Without this depth of understanding, managers are likely to make less-than-optimal decisions about integrated CASE and may abandon the technology too soon. The influence of learning curves on CASE tools and the adaptation of learning-curve models to integrate CASE are discussed. The three biggest tasks in the implementation of learning-curves in integrated CASE settings, locating a suitable data site, collecting the data, and validating the results, are also discussed     

Multiuser collaborative work in virtual environment based CASE tool

VRCASE is a virtual environment based Computer Aided Software Engineering (CASE) tool. It provides a 3D multiuser collaborative software modeling environment with automatic object-class abstraction, class diagram generation, and C++ skeleton generation facilities for assisting Object-Oriented software development. It allows multiple concurrent users to model software system collaboratively. To achieve efficient collaborative software development in VRCASE, we have proposed and implemented a Fine-grained locking and notification mechanism together with visual indicators to maintain system consistency among multiple concurrent users. The system evaluation shows that our approach can effectively support multiuser collaborative software design in VRCASE.     

基于LePUS的设计模式CASE工具的设计与实现

设计模式是软件工程界的热点,在面向对象软件设计中扮演着重要角色,自动化支持设计模式非常必要。为此,以LePUS语言为基础,提出了一个支持设计模式的CASE工具原型模型,该工具支持设计模式代码框架的自动生成,更重要的是该工具可以通过加入新的设计模式而得以扩展。此外,详细分析了实现中的源程序内部表示、设计模式实例化、动态模板生成技术等关键技术。     

中等COCOMO模型在中小型软件项目投资决策中的应用探讨

中等COCOMO模型是经过实际软件项目验证和修正的软件成本估算模型.文章将中等COCOMO模型应用于中小型软件项目投资决策,提出了一套简便而完整的中小型软件项目投资分析方法.     

PETOOL: MATLAB-based one-way and two-way split-step parabolic equation tool for radiowave propagation over variable terrain

A MATLAB-based one-way and two-way split-step parabolic equation software tool (PETOOL) has been developed with a user-friendly graphical user interface (GUI) for the analysis and visualization of radio-wave propagation over variable terrain and through homogeneous and inhomogeneous atmosphere. The tool has a unique feature over existing one-way parabolic equation (PE)-based codes, because it utilizes the two-way split-step parabolic equation (SSPE) approach with wide-angle propagator, which is a recursive forward–backward algorithm to incorporate both forward and backward waves into the solution in the presence of variable terrain. First, the formulation of the classical one-way SSPE and the relatively-novel two-way SSPE is presented, with particular emphasis on their capabilities and the limitations. Next, the structure and the GUI capabilities of the PETOOL software tool are discussed in detail. The calibration of PETOOL is performed and demonstrated via analytical comparisons and/or representative canonical tests performed against the Geometric Optic (GO) + Uniform Theory of Diffraction (UTD). The tool can be used for research and/or educational purposes to investigate the effects of a variety of user-defined terrain and range-dependent refractivity profiles in electromagnetic wave propagation.

Program summary

Program title: PETOOL (Parabolic Equation Toolbox)Catalogue identifier: AEJS_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJS_v1_0.htmlProgram obtainable from: CPC Program Library, Queen?s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 143 349No. of bytes in distributed program, including test data, etc.: 23 280 251Distribution format: tar.gzProgramming language: MATLAB (MathWorks Inc.) 2010a. Partial Differential Toolbox and Curve Fitting Toolbox requiredComputer: PCOperating system: Windows XP and VistaClassification: 10Nature of problem: Simulation of radio-wave propagation over variable terrain on the Earth?s surface, and through homogeneous and inhomogeneous atmosphere.Solution method: The program implements one-way and two-way Split-Step Parabolic Equation (SSPE) algorithm, with wide-angle propagator. The SSPE is, in general, an initial-value problem starting from a reference range (typically from an antenna), and marching out in range by obtaining the field along the vertical direction at each range step, through the use of step-by-step Fourier transformations. The two-way algorithm incorporates the backward-propagating waves into the standard one-way SSPE by utilizing an iterative forward–backward scheme for modeling multipath effects over a staircase-approximated terrain.Unusual features: This is the first software package implementing a recursive forward–backward SSPE algorithm to account for the multipath effects during radio-wave propagation, and enabling the user to easily analyze and visualize the results of the two-way propagation with GUI capabilities.Running time: Problem dependent. Typically, it is about 1.5 ms (for conducting ground) and 4 ms (for lossy ground) per range step for a vertical field profile of vector length 1500, on Intel Core 2 Duo 1.6 GHz with 2 GB RAM under Windows Vista.     

An approach and tool for measurement of state variable based data-flow test coverage for aspect-oriented programs

ContextData-flow testing approaches have been used for procedural and object-oriented programs, and shown to be effective in detecting faults. However, few such approaches have been evaluated for aspect-oriented programs. In such programs, data-flow interactions can occur between base classes and aspects, which can affect the behavior of both. Faults resulting from such interactions are hard to detect unless the interactions are specifically targeted during testing.ObjectiveThis paper presents an approach and tool implementation for measuring data-flow coverage based on state variables defined in base classes or aspects in AspectJ programs. The paper also reports on an empirical study that compares the cost and effectiveness of data-flow test criteria that are based on state variables with two control-flow criteria.MethodEffectiveness of the criteria was evaluated for various fault types. Cost-effectiveness of test suites that cover all state variable definition-use associations (DUAs) was evaluated for three coverage levels: 100%, 90%, and 80%.ResultsThe effort needed to obtain a test case that achieves data-flow coverage is higher than the effort needed to obtain a test case that covers a block or a branch in an advised class. Covering certain data flow associations requires more effort than for other types of data flow associations. The data-flow test criteria based on state variables of a base-class are in general more effective than control-flow criteria.ConclusionsOverall, it is cost-effective to obtain test suites at the 90% coverage level of data-flow criteria.     

Markov regenerative stochastic Petri nets with general execution policies: supplementary variable analysis and a prototype tool

Stochastic Petri nets (SPNs) with general firing time distributions are considered. Generally timed transitions can have general execution policies: the preemption policy may be preemptive repeat different (prd) or preemptive resume (prs) and the firing time distribution can be marking-dependent. A stationary analysis method covering all possible combinations is presented by means of supplementary variables. The method is implemented in a prototype tool SPNica which is based on Mathematica. The use of the general execution policies is illustrated by a WWW server model.     

CASE planning and the software process

Automating a software process magnifies its strengths and aceentuates its weaknesses. Automation can make an effective process more effective, but it can also make a chaotic process even worse-and at considerable expense. Anyone who buys expensive tools to solve an ill-defined problem is likely to be disappointed. Unless such tools are obtained as part of a thoughtful software process improvement plan, the purchase could be an expensive mistake. This article discusses software process maturity and its relationship to planning and installing computer-aided software engineering (CASE) systems. Although process is not a magic answer (there isn't one), the key issues are discussed from a process perspective, and guidelines are given for avoiding the most common pitfalls. Because CASE systems can involve significant investment, an economic justification may be necessary. The relevant financial considerations are therefore discussed, and some basic steps for producing such justifications are outlined. Finally, some key considerations for introducing and using CASE systems are discussed.This material is based in part on material from, Watts S. Humphrey,Managing the Software Process, Addison-Wesley, Reading, MA, © 1989. Reprinted with permission.This work was sponsored by the U.S. Department of Defense. The ideas and findings in this report should not be construed as an official DoD position. It is published in the interest of scientific and technical information exchange.     

Logistic curves and the formation of variable steps of spatial variable integration

In the present paper, we consider the differential equation of logistics curves, which is used for the formation of variable steps of the integration over space variables. It is shown that in this case, the transition from a minimum step to a maximum one is smooth without any breaks of the curves for a variable integration step. The algorithm for the calculation of variable steps of the variable integration of the space is proposed.     

Unified approach to structural optimization II: Variable segment boundaries and variable interior point constraints

Recently, Goh and Wang (1989) presented a unified approach for solving cross-section structural optimization problems under general constraints. In a continual development of the above unified approach, two important extensions have been made to enhance its versatility. They allow the optimization of variable piecewise segmental lengths and/or variable interior point constraint positions. This sequel paper shows how these extensions are incorporated in the unified approach and presents the derivation of gradient expressions (required in the optimization routine) of the objective functional and constraints with respect to these new variables. Some illustrative examples are solved to demonstrate the new features in the approach. Furthermore, a recent refinement in handling continuous state constraints is presented.On sabbatical leave from the Department of Civil Engineering, National University of Singapore, Kent Ridge, Singapore 0511     

Evaluating the usefulness of design rationale in CASE

Advanced systems development is composed of constant alternation between designing artifacts and debating the designs. This article evaluates the usefulness of the Debate Browser design rationale system in the MetaEdit+ CASE environment in one field setting. This usefulness is evaluated in terms of both the system's utility and usability. The research is composed of coaching, observation, and interviews, and it is supplemented through studying the design output. The evaluation suggests that the usefulness of the system is high. It points to advantages in reading design documents, via improved author-reader communication and the understanding of design solutions. This reduces the possibility of errors in design.     

The future of Unix in the CASE renaissance

The possibility of cross-fertilization of technology between scientific and commercial software user groups is examined. The role of the Unix operating system in providing the technological bridge between the two communities is explored. The development of computer-aided software engineering, which is viewed as being linked to future improvements in Unix, is discussed in this context     

A system of processes related by cause and effect Part II. A generalized complex variable

This paper establishes the mathematical foundations for the cause and effect relations of Part I. This is done by developing a theory of functions of a generalized complex variable     

Adoption and implementation of CASE tools in Taiwan

The aim of the research discussed here was to understand computer-aided software engineering (CASE) tool usage in Taiwan. Through a literature review, we developed two questionnaires – one for general respondents, the other for teachers and CASE agents. After pre-testing, 786 questionnaires were mailed out and 226 effective responses were obtained after two follow-up letters. Factor analyses were used to condense factors from `severity of critical problems in system development', `severity of perceived problems in CASE usage', `attitude toward CASE' and `CASE implementation success determinants'. Several external variables were considered in exploring their possible influence as well as the attitude and organizational features of the organizations that successfully used CASE. Path analyses were used to test an attitude model of CASE adoption and implementation success determinants. The results show that `the perceived problems in CASE tools' had no statistically significant influence on `attitude toward CASE' and very little influence on `perceived CASE improvement for system development critical problems'. In addition, we found that `methodology use' (including the usage before CASE adoption and consistency with the methodology supported by CASE) was the only statistically significant CASE implementation success determinant. Using only a `methodology use' variable could provide a way to discriminate the successful adopter from relatively unsuccessful adopter with a 75% correct classification rate.     

A method for calibrating of a trap pyroelectric detector in the UV–vis domain

The method and the experimental setup of a trap pyroelectric detector calibration against the BNM-INM Cryogenic Radiometer, at three laser wavelengths in the visible range were investigated. With this study, we have extended the absolute sensitivity measurements of the electrically calibrated trap pyroelectric detector (trap EPD) over 350–1850 nm range by spectroscopic reflectivity measurements. With our method, the relative standard uncertainty associated to the wedging factor was less then 0.4% (coverage factor, k = 1).