When to stop testing for large software systems with changing code

Developers of large software systems must decide how long software should be tested before releasing it. A common and usually unwarranted assumption is that the code remains frozen during testing. We present a stochastic and economic framework to deal with systems that change as they are tested. The changes can occur because of the delivery of software as it is developed, the way software is tested, the addition of fixes, and so on. Specifically, we report the details of a real time trial of a large software system that had a substantial amount of code added during testing. We describe the methodology, give all of the relevant details, and discuss the results obtained. We pay particular attention to graphical methods that are easy to understand, and that provide effective summaries of the testing process. Some of the plots found useful by the software testers include: the Net Benefit Plot, which gives a running chart of the benefit; the Stopping Plot, which estimates the amount of additional time needed for testing; and diagnostic plots. To encourage other researchers to try out different models, all of the relevant data are provided     

Chlorinated poly(vinyl chloride) (CPVC) engineering thermoplastic now a viable alternative

In the economic environment of today, as well as in the foreseeable future, the consumer and industry alike have to use critical value judgement on any purchase or investment made. Basically this requires stringent evaluation of cost and performance value of the selection made. In the field of engineering thermoplastics, the new generation of CPVC compounds offer a very unique and previously unattainable alternative to the plastics processor and consumer. Plastics processors can now use their expertise to develop the capability to successfully use these advanced CPVC compounds and gain the benefit of their cost/-performance values. This paper provides background on what CPVC is, what its rheological and thermal stability characteristics are, and describes its compounding, processing, and applications. It also describes the advances made over the past couple of years.     

Significance of seismic response spectrum normalization in nuclear power plant design

Peak ground acceleration has been used most commonly to normalize seismic response spectra. Apparently, there is a general consensus that this is not the best parameter for spectrum normalization. Several other parameters have been proposed, such as, peak acceleration-velocity-displacement triad, peak velocity and spectrum intensity. This paper presents statistical studies of response spectra from a number of recorded earthquake motions normalized by several different parameters. The parameters used are peak acceleration, peak velocity, spectrum intensity, spectrum ordinate, etc. Spectrum shapes are generated corresponding to 84 percentile probability level for different normalization parameters. These shapes are compared with the other standrad spectrum shapes used in the nuclear power plant design to investigate significance of different normalization techniques.     

Understanding Web home page perception

A home page is the gateway to an organization's Web site. To design effective Web home pages, it is necessary to understand the fundamental drivers of user's perception of Web pages. Not only do designers have to understand potential users' frame of mind, they also have at their choosing a stupefying array of attributes – including numerous font types, audio, video, and graphics – all of which can be arranged on a page in different ways, compounding the complexity of the design task. A theoretical model capable of explaining user reactions at a molar level should be invaluable to Web designers as a complement to prevalent intuitive and heuristic approaches. Such a model transcends piecemeal page attributes to focus on overall Web page perceptions of users. Reasoning that people perceive the cyberspace of Web pages in ways similar to their perception of physical places, we use Kaplan and Kaplan's informational model of place perception from the field of environmental psychology to predict that only two dimensions: understanding of information on a Web page, and the involvement potential of a Web page, should adequately capture Web page perception at a molar level. We empirically verify the existence of these dimensions and develop valid scales for measuring them. Using a home page as a stimulus in a lab experiment, we find that understanding and involvement together account for a significant amount of the variance in the attitude toward the Web page and in the intention to browse the underlying Web site. We show that the informational model is a parsimonious and powerful theoretical framework to measure users' perceptions of Web home pages and it could potentially serve as a guide to Web page design and testing efforts.     

Anytime clausal reasoning

Given any incomplete clausal propositional reasoner satisfying certain properties, we extend it to a family of increasingly‐complete, sound, and tractable reasoners. Our technique for generating these reasoners is based on restricting the length of the clauses used in chaining (Modus Ponens). Such a family of reasoners constitutes an anytime reasoner, since each propositional theory has a complete reasoner in the family. We provide an alternative characterization, based on a fixed‐point construction, of the reasoners in our anytime families. This fixed‐point characterization is then used to define a transformation of propositional theories into logically equivalent theories for which the base reasoner is complete; such theories are called “vivid”. Developing appropriate notions of vividness and techniques for compiling theories into vivid theories has already generated considerable interest in the KR community. We illustrate our approach by developing an anytime family based on Boolean constraint propagation. This revised version was published online in June 2006 with corrections to the Cover Date.     

突破新兴高效能电源要求上的限制

美国环保署(EPA)的能源之星(Energy Star)计划在2007年7月20日正式开始实施,这是针对个人电脑在不同负载下最低效能要求的规范.同时,它也为其他设备,包括企业服务器、外部电源(使用在如游戏机或笔记本电脑等)以及一系列家用设备规划或制定了类似的要求.     

6‐Aryl and Heterocycle Quinazoline Derivatives as Potent EGFR Inhibitors with Improved Activity toward Gefitinib‐Sensitive and ‐Resistant Tumor Cell Lines

A group of novel anilinoquinazoline derivatives with variable aryl and heterocyclic substituents at position 6 were synthesized and tested for their EGFR‐inhibitory activity. Aryl and heterocyclic rings were attached to the quinazoline scaffold through different linkages such as imine, amide, and thiourea. Most of the aryl and heterocyclic derivatives showed potent inhibition of wild‐type EGFR with IC₅₀ values in the low nanomolar range. Among these, thiourea derivatives 6 a , 6 b and compound 10 b also retained significant activity toward the gefitinib‐insensitive EGFR^T790M/L858R mutant, displaying up to 24‐fold greater potency than gefitinib. In addition, cell growth inhibitory activity was tested against cancer cell lines with wild‐type (KB cells) and mutant EGFR (H1975 cells). Several compounds including 6 a were found to be more potent than the reference compound gefitinib toward both cell lines, as was the case for compound 10 b against H1975 cells. Therefore, compounds 6 a and 10 b in particular may serve as new leads for the development of inhibitors effective against wild‐type EGFR as well as gefitinib‐resistant mutants.     

Poly(ethylene-co-vinyl alcohol)/Titanium Dioxide Nanocomposite: Preparation and Characterization of Properties for Potential Use in Bone Tissue Engineering

A series of poly(ethylene-co-vinyl alcohol)/titanium dioxide (PEVAL/TiO₂) nanocomposites containing 1, 2, 3, 4 and 5 wt% TiO₂ were prepared by the solvent casting method. These prepared hybrid materials were characterized by Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The pores and their interconnections inside these nanocomposites were created using naphthalene microparticles used as a porogen after having been extracted by sublimation under a high vacuum at temperatures slightly below the glass transition temperature. A cellular activity test of these hybrid materials was performed on human gingival fibroblast cells (HGFs) in accordance with ISO 10993-5 and ISO 10993-12 standards. The bioviability (cell viability) of HGFs was evaluated after 1, 4 and 7 days using Alamar Blue^®. The results were increased cell activity throughout the different culture times and a significant increase in cell activity in all samples from Day 1 to Day 7, and all systems tested showed significantly higher cell viability than the control group on Day 7 (p < 0.002). The adhesion of HGFs to the scaffolds studied by SEM showed that HGFs were successfully cultured on all types of scaffolds.     

Optical,crystallographic and Judd–Ofelt analysis of europium doped Sr6Y2Al4O15 nanocrystals for NUV-WLED fabrication

Journal of Materials Science: Materials in Electronics - A very convenient and energy-saving route named Solution-Combustion Synthesis had been adopted to prepare a sequence of...