An Update on Effort Estimation in Agile Software Development: A Systematic Literature Review

[EN] Software developers require effective effort estimation models to facilitate project planning. Although Usman et al. systematically reviewed and synthesized the effort estimation models and practices for Agile Software Development (ASD) in 2014, new evidence may provide new perspectives for researchers and practitioners. This article presents a systematic literature review that updates the Usman et al. study from 2014 to 2020 by analyzing the data extracted from 73 new papers. This analysis allowed us to identify six agile methods: Scrum, Xtreme Programming and four others, in all of which expert-based estimation methods continue to play an important role. This is particularly the case of Planning Poker, which is very closely related to the most frequently used size metric (story points) and the way in which software requirements are specified in ASD. There is also a remarkable trend toward studying techniques based on the intensive use of data. In this respect, although most of the data originate from single-company datasets, there is a significant increase in the use of cross-company data. With regard to cost factors, we applied the thematic analysis method. The use of team and project factors appears to be more frequent than the consideration of more technical factors, in accordance with agile principles. Finally, although accuracy is still a challenge, we identified that improvements have been made. On the one hand, an increasing number of papers showed acceptable accuracy values, although many continued to report inadequate results. On the other, almost 29% of the papers that reported the accuracy metric used reflected aspects concerning the validation of the models and 18% reported the effect size when comparing models.This work was supported by the Spanish Ministry of Science, Innovation and Universities through the Adapt@Cloud Project under Grant TIN2017-84550-R.Fernández-Diego, M.; Méndez, ER.; González-Ladrón-De-Guevara, F.; Abrahao Gonzales, SM.; Insfran, E. (2020). An Update on Effort Estimation in Agile Software Development: A Systematic Literature Review. IEEE Access. 8:166768-166800. https://doi.org/10.1109/ACCESS.2020.3021664S166768166800

Modeling and Analyzing Cyber-Physical Systems Using Hybrid Predicate Transition Nets

Cyber-Physical Systems (CPSs) are software controlled physical devices that are being used everywhere from utility features in household devices to safety-critical features in cars, trains, aircraft, robots, smart healthcare devices. CPSs have complex hybrid behaviors combining discrete states and continuous states capturing physical laws. Developing reliable CPSs are extremely difficult. Formal modeling methods are especially useful for abstracting and understanding complex systems and detecting and preventing early system design problems. To ensure the dependability of formal models, various analysis techniques, including simulation and reachability analysis, have been proposed in recent decades. This thesis aims to provide a unified formal modeling and analysis methodology for studying CPSs. Firstly, this thesis contributes to the modeling and analysis of discrete, continuous, and hybrid systems. This work enhances modeling of discrete systems using predicate transition nets (PrTNs) by fully realizing the underlying specification through incorporating the first-order logic with set theory, improving the type system, and providing incremental model composition. This work enhances the technique of analyzing discrete systems using PrTN by improving the simulation algorithm and its efficient implementation. This work also improves the analysis of discrete systems using SPIN by providing a more accurate and complete translation method. Secondly, this work contributes to the modeling and analysis of hybrid systems by proposing an extension of PrTNs, hybrid predicate transition nets (HPrTNs). The proposed method incorporates a novel concept of token evolution, which nicely addresses the continuous state evolution and the conflicts present in other related works. This work presents a powerful simulation capability that can handle linear, non-linear dynamics, transcendental functions through differential equations. This work also provides a complementary technique for reachability analysis through the translation of HPrTN models for analysis using SpaceEx

A Method and Tool for Finding Concurrency Bugs Involving Multiple Variables with Application to Modern Distributed Systems

Concurrency bugs are extremely hard to detect due to huge interleaving space. They are happening in the real world more often because of the prevalence of multi-threaded programs taking advantage of multi-core hardware, and microservice based distributed systems moving more and more applications to the cloud. As the most common non-deadlock concurrency bugs, atomicity violations are studied in many recent works, however, those methods are applicable only to single-variable atomicity violation, and don\u27t consider the specific challenge in distributed systems that have both pessimistic and optimistic concurrency control. This dissertation presents a tool using model checking to predict atomicity violation concurrency bugs involving two shared variables or shared resources. We developed a unique method inferring correlation between shared variables in multi-threaded programs and shared resources in microservice based distributed systems, that is based on dynamic analysis and is able to detect the correlation that would be missed by static analysis. For multi-threaded programs, we use a binary instrumentation tool to capture runtime information about shared variables and synchronization events, and for microservice based distributed systems, we use a web proxy to capture HTTP based traffic about API calls and the shared resources they access including distributed locks. Based on the detected correlation and runtime trace, the tool is powerful and can explore a vast interleaving space of a multi-threaded program or a microservice based distributed system given a small set of captured test runs. It is applicable to large real-world systems and can predict atomicity violations missed by other related works for multi-threaded programs and a couple of previous unknown atomicity violation in real world open source microservice based systems. A limitation is that redundant model checking may be performed if two recorded interleaved traces yield the same partial order model

Automatic sentence annotation for more useful bug report summarization

Bug reports are a useful software artifact with software developers referring to them for various information needs. As bug reports can become long, users of bug reports may need to spend a lot of time reading them. Previous studies developed summarizers and the quality of summaries was determined based on human-created gold-standard summaries. We believe creating such summaries for evaluating summarizers is not a good practice. First, we have observed a high level of disagreement between the annotated summaries. Second, the number of annotators involved is lower than the established minimum for the creation of a stable annotated summary. Finally, the traditional fixed threshold of 25% of the bug report word count does not adequately serve the different information needs. Consequently, we developed an automatic sentence annotation method to identify content in bug report comments which allows bug report users to customize a view for their task-dependent information needs

Annual record no. 48

INHIGEO produces an annual publication that includes information on the commission's activities, national reports, book reviews, interviews and occasional historical articles.N

Calibración de un algoritmo de detección de anomalías marítimas basado en la fusión de datos satelitales

La fusión de diferentes fuentes de datos aporta una ayuda significativa en el proceso de toma de decisiones. El presente artículo describe el desarrollo de una plataforma que permite detectar anomalías marítimas por medio de la fusión de datos del Sistema de Información Automática (AIS) para seguimiento de buques y de imágenes satelitales de Radares de Apertura Sintética (SAR). Estas anomalías son presentadas al operador como un conjunto de detecciones que requieren ser monitoreadas para descubrir su naturaleza. El proceso de detección se lleva adelante primero identificando objetos dentro de las imágenes SAR a través de la aplicación de algoritmos CFAR, y luego correlacionando los objetos detectados con los datos reportados mediante el sistema AIS. En este trabajo reportamos las pruebas realizadas con diferentes configuraciones de los parámetros para los algoritmos de detección y asociación, analizamos la respuesta de la plataforma y reportamos la combinación de parámetros que reporta mejores resultados para las imágenes utilizadas. Este es un primer paso en nuestro objetivo futuro de desarrollar un sistema que ajuste los parámetros en forma dinámica dependiendo de las imágenes disponibles.XVI Workshop Computación Gráfica, Imágenes y Visualización (WCGIV)Red de Universidades con Carreras en Informática (RedUNCI

2006-2007 University of Memphis directory

University of Memphis student, faculty, and staff telephone directory for 2006-2007, a project of the Department of Marketing, Communications and Special Events.https://digitalcommons.memphis.edu/speccoll-ua-pub-directories/1052/thumbnail.jp

An assessment of energy use as a rural development strategy: the case of Chiwundura communal area, Zimbabwe

Households in Chiwundura Communal Area continue to depend on traditional biomass fuels, that is, fuelwood, agricultural residues and in some cases dung. This is despite the fact that grid electrification has been introduced in the communal area. A few households have been able to adopt the grid electrification whilst the rest remain rooted in the use of the inefficient and polluting traditional biomass. Some of those who have adopted the grid electricity only use it for lighting and entertainment whilst they continue to use fuelwood for cooking. A number of households that have connected to grid electricity have reverted to the use of the traditional biomass. This means that the generality of people in Chiwundura Communal Area continue to be subjected to energy poverty, which is a constrained access to modern energy services such as electricity. As a result these households will not be able to meet the millennium development goals among many other achievements. This state of affairs motivated the researcher to conduct this study. The study wanted to find out why the transition from traditional biomass energy forms to modern energy services was slow in Chiwundura Communal Area. The study also wanted to establish the factors that influenced household en ergy choices as well as establish the ways in which the traditional biomass energy forms had affected the livelihoods of households in the study area. In order to get information on the above mentioned questions, this study which was a case study of Chiwundura Communal Area utilised the triangulation of both qualitative and quantitative techniques. These methods were meant to complement each other and benefit from the strengths of each method. The study used questionnaires, interviews, observations, transect walks, focus group discussions and content analysis. The researcher spent up to three months in the study area so as to get first hand information on the issues under study. A total of 215 households and 106 school children were conveniently sampled to respond to the questionnaires whilst fifty household heads participated in the interviews. The study looked at three energy theories namely the energy ladder, the leapfrogging and the multiple fuels use models as well as consumption and decision making theories to open this discussion. The study made a number of critical findings. Firstly, there was very little transition as most households remained as users of biomass energy; hence they were at the lower rungs of the energy ladder. Those that had moved up the ladder tended to back switch to the use of fuelwood. This made them multiple fuel users. Generally fuelwood was the dominant source of energy as it was used mainly for cooking, space and water heating, space lighting and other domestic needs such as smoking meat. About 22% of all respondents were connected to the grid and used electricity mainly for lighting. Candles, paraffin, gensets and solar energy were part of the energy mix. It was established that income was the most important determinant in the energy choices made by the different households. Most of the households were peasant farmers who could not harvest excess crops for the market. A few households with members in paid employment or obtained remittances from relatives in South Africa or the Diaspora were able to get connected to the grid or could afford to purchase fuelwood from vendors. Households could not procure solar house systems as the start up costs were beyond their reach. Those who were able to acquire generators could not run them for many hours as they could not afford to refuel them regularly. Household characteristics such as age and education of household- head were also important factors. It was however established that cultural and traditional factors were as usual not given the attention they deserved yet they were very significant in determining the type of fuel a household chose. Food preparation and taste always played an important role in determining whether a household chose traditional fuels for certain cuisines. It was also realised that failure by numerous households in the study area to access modern energy sources meant that they could not attain the millennium development goals by 2015. They could not move out of abject poverty as they lacked irrigation schemes to assure them of food security. Universal access to education was affected by lack of light to use for studying and reading after hours. Adult education was also frustrated. The boy child was worst affected as he came to school late or at times missed school altogether collecting fuelwood for the household. In Chiwundura Communal Area men and boys were responsible for collecting fuelwood. This signified a shift in gender roles. Men and boys took it upon themselves to have these responsibilities as women and girls could not walk the long distances. The health of the household particularly women and children who spent several hours close to the fire was compromised as most huts were poorly ventilated. They therefore could not adequately deal with indoor air pollution challenges. Other MDGs were also likely not to be achieved by the families. The study also found out that men were not dictatorial in determining the fuel that a household used. Some form of democracy existed within homes and negotiations between husband and wife often took place away from the public domain. Oftentimes women often aped their colleagues who owned modern energy technologies within the villages; hence they pressurised their husbands to buy them SHSs and gensets. This was conspicuous consumption. The study established that there was need for modern energy in the study area. Grid electricity was not the panacea for this as it was beyond the reach of many. It was therefore important to look at renewable energy forms such as gel fuel, SHSs and biogas. It was also pertinent to educate and make households aware of dangers posed by indoor air pollution. The government and different stakeholders must give it equal importance and publicity as that given to HIV and AIDS as it kills several children annually. Housing interventions should be made so that households build huts with proper ventilation