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11.
Realizing quality improvement through test driven development: results and experiences of four industrial teams 总被引:2,自引:2,他引:0
Nachiappan Nagappan E. Michael Maximilien Thirumalesh Bhat Laurie Williams 《Empirical Software Engineering》2008,13(3):289-302
Test-driven development (TDD) is a software development practice that has been used sporadically for decades. With this practice,
a software engineer cycles minute-by-minute between writing failing unit tests and writing implementation code to pass those
tests. Test-driven development has recently re-emerged as a critical enabling practice of agile software development methodologies.
However, little empirical evidence supports or refutes the utility of this practice in an industrial context. Case studies
were conducted with three development teams at Microsoft and one at IBM that have adopted TDD. The results of the case studies
indicate that the pre-release defect density of the four products decreased between 40% and 90% relative to similar projects
that did not use the TDD practice. Subjectively, the teams experienced a 15–35% increase in initial development time after
adopting TDD.
Nachiappan Nagappan is a researcher in the Software Reliability Research group at Microsoft Research. He received his MS and PhD from North Carolina State University in 2002 and 2005, respectively. His research interests are in software reliability, software measurement and empirical software engineering. Dr. E. Michael Maximilien (aka “max”) is a research staff member at IBM’s Almaden Research Center in San Jose, California. Prior to joining ARC, he spent ten years at IBM’s Research Triangle Park, N.C., in software development and architecture. He led various small- to medium-sized teams, designing and developing enterprise and embedded Java™ software; he is a founding member and contributor to three worldwide Java and UML industry standards. His primary research interests lie in distributed systems and software engineering, especially Web services and APIs, mashups, Web 2.0, SOA (service-oriented architecture), and Agile methods and practices. He can be reached through his Web site (maximilien.org) and blog (blog.maximilien.com). Thirumalesh Bhat is a Development Manager at Microsoft Corporation. He has worked on several versions of Windows and other commercial software systems at Microsoft. He is interested in software reliability, testing, metrics and software processes. Laurie Williams is an associate professor of computer science at North Carolina State University. She teaches software engineering and software reliability and testing. Prior to joining NCSU, she worked at IBM for nine years, including several years as a manager of a software testing department and as a project manager for a large software project. She was one of the founders of the XP Universe conference in 2001, the first US-based conference on agile software development. She is also the lead author of the Pair Programming Illuminated book and a co-editor of the Extreme Programming Perspectives book. 相似文献
Laurie WilliamsEmail: |
Nachiappan Nagappan is a researcher in the Software Reliability Research group at Microsoft Research. He received his MS and PhD from North Carolina State University in 2002 and 2005, respectively. His research interests are in software reliability, software measurement and empirical software engineering. Dr. E. Michael Maximilien (aka “max”) is a research staff member at IBM’s Almaden Research Center in San Jose, California. Prior to joining ARC, he spent ten years at IBM’s Research Triangle Park, N.C., in software development and architecture. He led various small- to medium-sized teams, designing and developing enterprise and embedded Java™ software; he is a founding member and contributor to three worldwide Java and UML industry standards. His primary research interests lie in distributed systems and software engineering, especially Web services and APIs, mashups, Web 2.0, SOA (service-oriented architecture), and Agile methods and practices. He can be reached through his Web site (maximilien.org) and blog (blog.maximilien.com). Thirumalesh Bhat is a Development Manager at Microsoft Corporation. He has worked on several versions of Windows and other commercial software systems at Microsoft. He is interested in software reliability, testing, metrics and software processes. Laurie Williams is an associate professor of computer science at North Carolina State University. She teaches software engineering and software reliability and testing. Prior to joining NCSU, she worked at IBM for nine years, including several years as a manager of a software testing department and as a project manager for a large software project. She was one of the founders of the XP Universe conference in 2001, the first US-based conference on agile software development. She is also the lead author of the Pair Programming Illuminated book and a co-editor of the Extreme Programming Perspectives book. 相似文献
12.
Tests of random, alternating cuts on a ball-model of in Al–Cu alloy have been run to check the kinetics at which disordering occurs in an initially ordered precipitate subject to cyclic strain. In addition, fatigue tests at low temperature (78 K) and various microscopical observations have been made on Al–Ag alloy containing GP zones to check whether a structure containing an initially disordered precipitate will cyclically soften or not. It was thus found that the ball model disorders as a function of accumulated plastic strain consistently with the kinetics of cyclic softening in actual material. Further, Al–Ag alloy was found not to soften at 78 K. Both of these results supoort the disordering hypothesis of cyclic softening over the dissolution or shearing-off mechanisms, although other systems may be subject to these mechanisms. In spite of the low temperature at which the Al–Ag alloy was tested, small / precipitates were found to have formed in the longest lived test; however, this result did not interfere with the validity of the experiment as it did previously at room temperature. The fatigue lives at 78 K were much longer than those previously measured at room temperature although the failure mechanisms were not affected at high strain and only somewhat affected at low strain (there was increased incidence of transgranular crack nucleation and propagation).
Résumé Des essais d'application de coups alternés et aléatoires sur un modèle de simulation par des billes de la phase dans les alliages de Cu–Al ont été effectués en vue de vérifier la cinétique suivant laquelle se produisent des désordres dans un précipité initialement ordonné et soumis à des déformations cycliques. En outre, des essais de fatigue à basse température (78°K) ainsi que diverses observations microscopiques ont été effectués sur un alliage Al–Ag comportant des zones GP en vue de vérifier si une structure comportant un précipité initialement en désordre subirait un adoucissement cyclique ou non. On a donc trouvé que le modèle de utilisant des billes fait état de désordres en fonction de l'accumulation de la déformation plastique et ce en rapport avec la cinétique d'adoucissement cyclique dans le matériau réel. En outre, l'alliage Al–Ag s'est révélé ne pas s'adoucir à 78°K. Ces deux résultats soutiennent l'hypothèse suivant laquelle un adoucissement cyclique s'accompagne de désordres plutôt que de mécanismes de disolution ou de séparation par cisaillement, bien que d'autres systèmes puissent être sujets à ces mécanismes. En dépit de la basse température à laquelle l'alliage Al–Ag a été essayé, on a trouvé de petits précipités / qui se sont formés au cours des essais, les plus longs. Cependant, ce résultat ne gène pas la validité de l'expérience comme c'était le cas précédemment à température ambiante. Les vies en fatigue à 78°K ont été trouvées bien plus longues que celles mesurées précédemment à température ambiante, en dépit du fait que le mécanisme de rupture n'ait pas été affecté sous les déformations élevées et ne l'a été que quelque peu sous les déformations faibles, auxquelles apparait une incidence croissante d'une nucléation et d'une propagation d'une fissure transgranulaire.相似文献
13.
X. Darok V. Bhat L. Aymard L. Dupont L. Laffont J.-M. Tarascon 《Thin solid films》2006,515(4):1299-1306
Mg-Ni thin films were grown using Pulsed Laser Deposition. In situ optical changes from shiny metallic to transparent states were observed for films deposited in vacuum and under an Ar/H2 gas mixture (93/7%), respectively. Optical changes were also achieved by ex situ hydrogenation under hydrogen gas pressure of 15 bars at 200 °C. However, after ex situ hydrogenation, the optical transmittance of the Mg-based hydrogenated thin films did not exceed 25%. Such limitation was attributed to oxygen contamination, as deduced by High Resolution Transmission Electron Microscopy observations, showing the co-existence of both Mg-based and MgO phases for as-deposited films. A significant decrease in oxygen contamination was successfully achieved with the addition of carbon, leading to the preparation of (Mg-based)-Cx (x < 20%) thin films showing a faster and easier hydrogenation. 相似文献
14.
M.H. Hu Hong Ky Nguyen Kechang Song Yabo Li N.J. Visovsky Xingsheng Liu N. Nishiyama S. Coleman L.C. Hughes Jr. J. Gollier W. Miller R. Bhat Chung-En Zah 《Photonics Technology Letters, IEEE》2006,18(4):616-618
We report on the static and dynamic performance of high-power and high-modulation-speed 1060-nm distributed Bragg reflector (DBR) lasers for green-light emission by second-harmonic generation. Single-wavelength power of 387 mW at 1060-nm wavelength and green power as high as 99.5 mW were achieved. A thermally induced wavelength tuning of 2.4 nm and a carrier-induced wavelength tuning of -0.85 nm were obtained by injecting current into the DBR section. Measured rise-fall times of 0.2 ns for direct intensity modulation and 0.6 ns for wavelength modulation make the lasers suitable for >50-MHz green-light modulation applications. 相似文献
15.
Total radiation dose at geostationary orbit 总被引:1,自引:0,他引:1
Active semiconductor components in satellites are sensitive to accumulated ionization radiation dose. Radiation dose and shielding estimations for electronic components are usually carried out using NASA models of space radiation particle flux. Accurate measurement of accumulated dose during the life of a satellite is essential for optimizing radiation shielding design for electronic components. Dosimeters were designed using radiation sensitive field-effect transistors (RADFETs) and accumulated dose at geostationary orbit was measured. Radiation dose as measured by these dosimeters with spherical aluminum shields are presented and compared with NASA model doses. 相似文献
16.
The effect of technology scaling (0.5-0.09 /spl mu/m) on single event upset (SEU) phenomena is investigated using full two-dimensional device simulation. The SEU reliability parameters, such as critical charge (Q/sub crit/), feedback time (T/sub fd/) and linear energy transfer (LET), are estimated. For L/sub g/<0.18 /spl mu/m, the source node collects a significant fraction of radiation-induced charge resulting in an increase of LET, despite the lower critical charge at the sensitive drain node. The effect of striking location on LET confirms this finding. 相似文献
17.
The problem of accurate depth estimation using stereo in the presence of specular reflection is addressed. Specular reflection, a fundamental and ubiquitous reflection mechanism, is viewpoint dependent and can cause large intensity differences at corresponding points, resulting in significant depth errors. We analyze the physics of specular reflection and the geometry of stereopsis which lead to a relationship between stereo vergence, surface roughness, and the likelihood of a correct match. Given a lower bound on surface roughness, an optimal binocular stereo configuration can be determined which maximizes precision in depth estimation despite specular reflection. However, surface roughness is difficult to estimate in unstructured environments. Therefore, trinocular configurations, independent of surface roughness are determined such that at each scene point visible to all sensors, at least one stereo pair can produce correct depth. We have developed a simple algorithm to reconstruct depth from the multiple stereo pairs. 相似文献
18.
M. Harish Bhat M. Kandavel Munia Ganguli K. J. Rao 《Bulletin of Materials Science》2004,27(2):189-198
Lithium ion conductivity has been investigated in a boro-tellurite glass system, LiCl.LiBO2.TeO2. In the absence of LiCl, the conductivity increases with increasing non-bridging oxygen (NBO) concentration. LiCl addition
has little influence on total conductivity although the observed barriers are low. Formation of LiCl clusters appears evident.
In the a.c. conductivity and dielectric studies, it is observed that the conductivity mechanism remains the same in all compositions
and at all temperatures. A suggestion is made that Li+ ion transport may be driven by bridging oxygen ↔r non-bridging oxygen (BO ↔r NBO) switching, which is why the two different
types of Li+ ions in the clusters and in the neighbourhood of NBOs, do not manifest in the conductivity studies. 相似文献
19.
N. Jegadeeswaran M. R. Ramesh S. Prakrathi K. Udaya Bhat 《Transactions of the Indian Institute of Metals》2014,67(1):87-93
The coal burned natural gas in contact with gas turbine can contain impurities of sodium, sulfur, vanadium, silicon and possibly lead and phosphorous, induce accelerated hot corrosion during long term operation. Coatings are frequently applied on gas turbine components in order to restrict surface degradation and to obtain accurate lifetime expectancies. High velocity oxy-fuel thermal spraying has been used to deposit Stellite-6 alloy coatings on turbine alloys. Hot corrosion behavior of the coatings were investigated for 50 cycles of 1 h heating at 800 °C followed by 20 min cooling in presence of Na2SO4 + 50 % V2O5 measuring weight gain (or loss). X-ray diffraction and SEM/EDAX techniques were used to characterize the oxide scale formed. The superior performance of Stellite-6 coating can be attributed to continuous and protective thin oxide scale of CoO, Cr2O3 and SiO2 formed on the surface. The coating region beneath this thin oxide scale was partially oxidized. Uncoated SuperCo-605 and MDN-121 showed less weight gain than Stellite-6 coated samples, but they showed spalling or sputtering during cyclic oxidation. Stellite-6 coating was dense and pore free even after 50 cycles, indicating that it can resist the hot corrosion cycle. 相似文献
20.
Mahesh Kumar Thirumaleshwara N. Bhat Basanta Roul Mohana K. Rajpalke A.T. Kalghatgi S.B. Krupanidhi 《Materials Research Bulletin》2012,47(6):1306-1309
The n-type GaN layers were grown by plasma-assisted MBE and either intentionally doped with Si or unintentionally doped. The optical characteristics of a donor level in Si-doped, GaN were studied in terms of photoluminescence (PL) spectroscopy as a function of electron concentration. Temperature dependent PL measurements allowed us to estimate the activation energy of a Si-related donor from temperature-induced decay of PL intensity. PL peak positions, full width at half maximum of PL and activation energies are found to be proportional to the cube root of carrier density. The involvement of donor levels is supported by the temperature-dependent electron concentration measurements. 相似文献