Hacia un modelo híbrido de simulación de la producción de software en un entorno multiproyecto

La simulación del ciclo de vida de los proyectos software o de partes de éste es un activo campo de investigación en la ingeniería del software. El presente informe analiza la literatura sobre modelos de simulación que puedan se útiles para estudiar las organizaciones de desarrollo de software. La finalidad del trabajo es construir un modelo de simulación en el que se puedan implementar diversas políticas de asignación de recursos basadas en las técnicas de gestión de proyectos propias de la investigación operativa en un contexto de mejora de procesos y teniendo en cuenta el carácter multiproyecto.Ministerio de Educación y Ciencia TIN2007-67843- C06-0

Teorí­a de colas. Propuesta de un simulador didáctico

Los simuladores de abstracciones de problemas reales son uno de los usos de las TIC en educación. El estudio de modelos basados en la Teorí­a de Colas radica en generar respuestas para optimizar el tiempo de espera ante un servicio determinado. En este sentido, se presenta la construcción de un simulador de un modelo de sistema basado en Teorí­a de Colas, para su implementación en un contexto de educación superior. El software permite simular y representar gráfica y visualmente el comportamiento del sistema, permitiendo cambiar los parámetros que definen el proceso de la simulación, facilitando la experimentación de los estudiantes. Para su validación se efectuaron corridas y experimentos que representa el Modelo de Cola M/M/1. La generación estocástica de los parámetros/valores produce resultados de desempeño más reales. En el documento se describe la introducción, la metodologí­a aplicada, los resultados enfatizando en la generación de informes utilizando distintos parámetros. Finalmente, se mencionan las conclusiones y posibles lí­neas para continuar el trabajo

Applications of simulation in maintenance research

The area of asset maintenance is becoming increasingly important as greater asset availability is demanded. This is evident in increasingly automated and more tightly integrated production systems as well as in service contracts where the provider is contracted to provide high levels of availability. Simulation techniques are able to model complex systems such as those involving maintenance and can be used to aid performance improvement. This paper examines engineering maintenance simulation research and applications in order to identify apparent research gaps. A systematic literature review was conducted in order to identify the gaps in maintenance systems simulation literature. Simulation has been applied to model different maintenance sub-systems (asset utilisation, asset failure, scheduling, staffing, inventory, etc.) but these are typically addressed in isolation and overall maintenance system behaviour is poorly addressed, especially outside of the manufacturing systems discipline. Assessing the effect of Condition Based Maintenance (CBM) on complex maintenance operations using Discrete Event Simulation (DES) is absent. This paper categorises the application of simulation in maintenance into eight categories

A systematic approach for resource allocation in software projects

a b s t r a c t The completion of reliable software products within their expected time frame represents a major problem for companies that develop software applications. Today, the software industry continues to struggle with delivering products in a timely manner. A major cause for delays is the training time required for engineers and other personnel to acquire the necessary skills to complete software tasks. Therefore, it is important to develop systematic personnel assignment processes that consider complete skill sets of candidates to provide solutions that reduce training time. This paper presents a novel methodology to assign resources to tasks when optimum skill sets are not available. The methodology takes into account existing capabilities of candidates, required levels of expertise, and priorities of required skills for the task. A sample case is used to show the model capabilities, and the results are compared with the current resource assignment approach. Published by Elsevier Ltd

The Effect of Communication Overhead on Software Maintenance Project Staffing: a Search-Based Approach

Brooks ’ milestone ‘Mythical Man Month ’ established the observation that there is no simple conversion between peo-ple and time in large scale software projects. Communica-tion and training overheads yield a subtle and variable re-lationship between the person-months required for a project and the number of people needed to complete the task within a given time frame. This paper formalises several instantiations of Brooks’ law and uses these to construct project schedule and staffing instances — using a search-based project staffing and scheduling approach — on data from two large real world maintenance projects. The results reveal the impact of dif-ferent formulations of Brooks ’ law on project completion time and on staff distribution across teams, and the influ-ence of other factors such as the presence of dependen-cies between work packages on the effect of communication overhead

The use of search-based optimization techniques to schedule and staff software projects: an approach and an empirical study

Allocating resources to a software project and assigning tasks to teams constitute crucial activities that affect project cost and completion time. Finding a solution for such a problem is NP-hard; this requires managers to be supported by proper tools in performing such an allocation. This paper shows how search-based optimization techniques can be combined with a queuing simulation model to address these problems. The obtained staff and task allocations aim to minimize the completion time and reduce schedule fragmentation. The proposed approach allows project managers to run multiple simulations, compare results and consider trade-offs between increasing the staffing level and anticipating the project completion date and between reducing the fragmentation and accepting project delays. The paper presents results from the application of the proposed search-based project planning approach to data obtained from two large scale commercial software maintenance projects

Assessing Staffing Needs for a Software Maintenance Project through Queuing Simulation

Abstract-We present an approach based on queuing theory and stochastic simulation to help planning, managing, and controlling the project staffing and the resulting service level in distributed multiphase maintenance processes. Data from a Y2K massive maintenance intervention on a large COBOL/JCL financial software system were used to simulate and study different service center configurations for a geographically distributed software maintenance project. In particular, a monolithic configuration corresponding to the customer's point-of-view and more fine-grained configurations, accounting for different process phases as well as for rework, were studied. The queuing theory and stochastic simulation provided a means to assess staffing, evaluate service level, and assess the likelihood to meet the project deadline while executing the project. It turned out to be an effective staffing tool for managers, provided that it is complemented with other project-management tools, in order to prioritize activities, avoid conflicts, and check the availability of resources

Software Reliability Growth Models from the Perspective of Learning Effects and Change-Point.

Increased attention towards reliability of software systems has led to the thorough analysis of the process of reliability growth for prediction and assessment of software reliability in the testing or debugging phase. With many frameworks available in terms of the underlying probability distributions like Poisson process, Non-Homogeneous Poisson Process (NHPP), Weibull, etc, many researchers have developed models using the Non-Homogeneous Poisson Process (NHPP) analytical framework. The behavior of interest, usually, is S-shaped or exponential shaped. S-shaped behavior could relate more closely to the human learning. The need to develop different models stems from the fact that nature of the underlying environment, learning effect acquisition during testing, resource allocations, application and the failure data itself vary. There is no universal model that fits everywhere to be called an Oracle. Learning effects that stem from the experiences of the testing or debugging staff have been considered for the growth of reliability. Learning varies over time and this asserts need for conduct of more research for study of learning effects.Digital copy of ThesisUniversity of Kashmi

Níveis de serviço e simulação computacional: um estudo de caso da influência de fatores no tempo de atendimento em uma praça de pedágio rodoviário.

A capacidade e o nível de serviço das instalações de pedágio ainda não foram formalmente abordados no Highway Capacity Manual, que reconhece e afirma que deve ser dada especial atenção às características únicas, restrições e atrasos causados por estas instalações de cobrança. Essa pesquisa buscou elucidar os seguintes questionamentos: como fatores humanos e operacionais influenciam o tempo de atendimento manual em praças de pedágio? E qual a relação com os níveis de serviço proporcionados pela empresa? Teve por objetivo avaliar os níveis de serviço oferecidos em uma praça de pedágio rodoviário por meio da simulação computacional, testando a influência de fatores na capacidade de atendimento manual. Para alcançar esse objetivo foi realizado um estudo de caso em uma praça de pedágio localizada no estado de Minas Gerais. A coleta de dados, realizada por intermédio de vídeos, documentos e visitas ao local, forneceu informações como a categoria do veículo, a forma de pagamento, o turno de trabalho, dia da semana e sexo do arrecadador; também forneceu o volume de veículos que passaram pela praça e sua composição. O trabalho pode ser dividido em duas etapas: a primeira buscando analisar a influência de fatores no tempo de atendimento por meio de análise estatística e DOE e a segunda etapa realizada por meio da modelagem e simulação, visando determinar o nível de serviço oferecido pela concessionária aos seus clientes. As conclusões principais da análise dos dados coletados mostram que os fatores Categoria do veículo, Forma de pagamento e Sexo do arrecadador são os que têm maior influência no tempo de atendimento, sendo o fator Categoria o mais impactante, aumentando significativamente o tempo de atendimento. A simulação computacional possibilitou avaliar o nível de serviço atual da praça de pedágio e também cenários diversos. A praça atualmente opera com um nível de serviço D em dias normais de funcionamento, no qual um veículo permanece no sistema entre 45 e 60 segundos. Entretanto, em feriados esse nível de serviço cai para E no turno da madrugada e para o F nos turnos da manhã e tarde. A pesquisa mostrou que existem alternativas e melhorias que podem ser aplicadas no ato de arrecadação manual da praça de pedágio estudada