促销也玩“票”

近期,《微型计算机》策划的“电脑城的明天在哪儿？”专题报道可谓鞭辟入里,说中了目前国内电脑城的症结所在,而电脑城几乎也有了思变的意识。从2009年3月6日至2009年5月1日,重庆泰兴电脑城向消费者发放IT消费券,凭消费券即可在泰兴网上商城购物时抵扣相应的金额。泰兴电脑城对此举的解释是响应“刺激消费,拉动内需“的号召。其实这事儿没那么复杂,不过是泰兴电脑城换了个花样搞促销罢了。     

一种新型软开关Buck变换器的研究

针对传统ZVT-PWM变换器的辅助开关硬关断的不足,提出了一种新型PWM控制的软开关Buck变换器方案,详细介绍了该新型软开关Buck变换器的拓扑结构及工作原理,并给出了具体的设计过程。新型软开关Buck变换器的辅助电路使主开关工作在零电压状态,所有的半导体器件均工作在软开关条件下,从而减小了开关损耗。仿真结果证明了该新型软开关Buck变换器方案的有效性。     

FENECIA: failure endurable nested-transaction based execution of composite Web services with incorporated state analysis

Interest in the Web services (WS) composition (WSC) paradigm is increasing tremendously. A real shift in distributed computing history is expected to occur when the dream of implementing Service-Oriented Architecture (SOA) is realized. However, there is a long way to go to achieve such an ambitious goal. In this paper, we support the idea that, when challenging the WSC issue, the earlier that the inevitability of failures is recognized and proper failure-handling mechanisms are defined, from the very early stage of the composite WS (CWS) specification, the greater are the chances of achieving a significant gain in dependability. To formalize this vision, we present the FENECIA (Failure Endurable Nested-transaction based Execution of Composite Web services with Incorporated state Analysis) framework. Our framework approaches the WSC issue from different points of view to guarantee a high level of dependability. In particular, it aims at being simultaneously a failure-handling-devoted CWS specification, execution, and quality of service (QoS) assessment approach. In the first section of our framework, we focus on answering the need for a specification model tailored for the WS architecture. To this end, we introduce WS-SAGAS, a new transaction model. WS-SAGAS introduces key concepts that are not part of the WS architecture pillars, namely, arbitrary nesting, state, vitality degree, and compensation, to specify failure-endurable CWS as a hierarchy of recursively nested transactions. In addition, to define the CWS execution semantics, without suffering from the hindrance of an XML-based notation, we describe a textual notation that describes a WSC in terms of definition rules, composability rules, and ordering rules, and we introduce graphical and formal notations. These rules provide the solid foundation needed to formulate the execution semantics of a CWS in terms of execution correctness verification dependencies. To ensure dependable execution of the CWS, we present in the second section of FENECIA our architecture THROWS, in which the execution control of the resulting CWS is distributed among engines, discovered dynamically, that communicate in a peer-to-peer fashion. A dependable execution is guaranteed in THROWS by keeping track of the execution progress of a CWS and by enforcing forward and backward recovery. We concentrate in the third section of our approach on showing how the failure consideration is trivial in acquiring more accurate CWS QoS estimations. We propose a model that assesses several QoS properties of CWS, which are specified as WS-SAGAS transactions and executed in THROWS. We validate our proposal and show its feasibility and broad applicability by describing an implemented prototype and a case study.     

On guiding the augmentation of an automated test suite via mutation analysis

Mutation testing has traditionally been used as a defect injection technique to assess the effectiveness of a test suite as represented by a “mutation score.” Recently, mutation testing tools have become more efficient, and industrial usage of mutation analysis is experiencing growth. Mutation analysis entails adding or modifying test cases until the test suite is sufficient to detect as many mutants as possible and the mutation score is satisfactory. The augmented test suite resulting from mutation analysis may reveal latent faults and provides a stronger test suite to detect future errors which might be injected. Software engineers often look for guidance on how to augment their test suite using information provided by line and/or branch coverage tools. As the use of mutation analysis grows, software engineers will want to know how the emerging technique compares with and/or complements coverage analysis for guiding the augmentation of an automated test suite. Additionally, software engineers can benefit from an enhanced understanding of efficient mutation analysis techniques. To address these needs for additional information about mutation analysis, we conducted an empirical study of the use of mutation analysis on two open source projects. Our results indicate that a focused effort on increasing mutation score leads to a corresponding increase in line and branch coverage to the point that line coverage, branch coverage and mutation score reach a maximum but leave some types of code structures uncovered. Mutation analysis guides the creation of additional “common programmer error” tests beyond those written to increase line and branch coverage. We also found that 74% of our chosen set of mutation operators is useful, on average, for producing new tests. The remaining 26% of mutation operators did not produce new test cases because their mutants were immediately detected by the initial test suite, indirectly detected by test suites we added to detect other mutants, or were not able to be detected by any test.

Social Propagation: Boosting Social Annotations for Web Mining

This paper is concerned with the problem of boosting social annotations using propagation, which is also called social propagation. In particular, we focus on propagating social annotations of web pages (e.g., annotations in Del.icio.us). Social annotations are novel resources and valuable in many web applications, including web search and browsing. Although they are developing fast, social annotations of web pages cover only a small proportion (<0.1%) of the World Wide Web. To alleviate the low coverage of annotations, a general propagation model based on Random Surfer is proposed. Specifically, four steps are included, namely basic propagation, multiple-annotation propagation, multiple-link-type propagation, and constraint-guided propagation. The model is evaluated on a dataset of 40,422 web pages randomly sampled from 100 most popular English sites and ten famous academic sites. Each page’s annotations are obtained by querying the history interface of Del.icio.us. Experimental results show that the proposed model is very effective in increasing the coverage of annotations while still preserving novel properties of social annotations. Applications of propagated annotations on web search and classification further verify the effectiveness of the model.     

Using formal methods to increase confidence in a home network system implementation: a case study

A home network system consists of multiple networked appliances, intended to provide more convenient and comfortable living for home users. Before being deployed, one has to guarantee the correctness, the safety, and the security of the system. Here, we present the approach chosen to validate the Java implementation of a home network system. We rely on the Java Modelling Language to formally specify and validate an abstraction of the system. This is a substantially revised version of our paper that appeared in the proceedings of the Workshop On Leveraging Applications of Formal Methods, Verification and Validation (ISoLA), Poitiers-Futuroscope, France, December 2007.     

人工环境中的环境电器

文章从环境心理学的角度出发,重点分析了当今人工环境的概念及其影响下的环境电器产品现状和前景。随着人们对生活环境质量越来越重视,环境电器产品必在人和环境互动关系中扮演重要角色。     

Characterization of AlPO systems,precursors of the novel basic catalyst family AlPON

XPS and DRIFTS (diffuse reflectance infrared spectroscopy) spectra of AlPO systems, formally AlPO₄-Al₂O₃, obtained by the sol-gel method have been studied in order to understand their geometric and electronic structure. Both DRIFTS and XPS demonstrate that the acidbase character of these samples depends on a structural modification. For low phosphorus content an amorphous spinel-like solid is proposed. This geometric arrangement alters the electronic density of oxide ions and phosphorus cations and hence their Lewis acid-base properties with respect to the amorphous solid having aluminium and phosphorus only in tetrahedral arrangement.     

Investigating the influence of the counter Si-cell on the optoelectronic performance of high-efficiency monolithically perovskites/silicon tandem cells under various optical sources

Nowadays, tandem structures have become a valuable competitor to conventional silicon solar cells, especially for perovskite over silicon, as metal halides surpassed Si with tunable bandgaps, high absorption coefficient, low deposition, and preparation costs. This led to a remarkable enhancement in the overall efficiency of the whole cell and its characteristics. Consequently, this expands the usage of photovoltaic technology in various fields of applications not only under conventional light source spectrum in outdoor areas, i.e., AM1.5G, but also under artificial light sources found indoors with broadband intensity values, such as Internet of things (IoTs) applications to name a few. We introduce a numerical model to analyze perovskite/Si tandem cells (PSSTCs) using both crystalline silicon (c-Si) and hydrogenated amorphous silicon (a-Si:H) experimentally validated as base cells. All proposed layers have been studied with J-V characteristics and energy band diagrams under AM1.5G by using SCAPS-1D software version 3.7.7. Thereupon, the proposed architectures were tested under various artificial lighting spectra. The proposed structures of Li4Ti5O12/CsPbCl3/MAPbBr3/CH3NH3PbI3/Si recorded a maximum power conversion efficiency (PCE) of 25.25% for c-Si and 17.02% for a-Si:H, with nearly 7% enhancement concerning the Si bare cell in both cases.     

The Golden Touch by Light: A Finely Engineered Luminogen Empowering High Photoactivatable and Photodynamic Efficiency for Cancer Phototheranostics

Photoactivatable agent is a powerful tool in biomedicine studies due to high-precision spatiotemporal control of light. However, those previously reported agents generally suffer from short wavelength, fluorescence self-quenching effect, and the lack of photosensitizing property, which severely restrict their practical applications. To address these issues, molecular engineering of 1,4-dihydropyridine derivatives is conducted to obtain an optimized agent, namely TPA-DHPy-Py, which exhibits low oxidation potential, high photoactivation efficiency, and excellent type I/II combined photodynamic activity. Concurrently, its photoactivated counterpart is featured by aggregation-induced near-infrared emission and remarkable reactive oxygen species (ROS) production efficiency. Upon photoactivation, TPA-DHPy-Py is capable of precisely identifying cancer cells from co-culturing cancer cells and normal cells without the assistance of any extra targeting units, and in situ monitoring lipid droplets and endoplasmic reticulum alteration under ROS stress, as well as achieving fluorescent visualization of tumor in vivo with supremely high imaging contrast. Furthermore, the unprecedented performance on photodynamic cancer therapy is demonstrated by the significant inhibition of tumor growth. Therefore, the photoactivatable TPA-DHPy-Py with dual-organelle-targeted and excellent photodynamic activity associated with self-monitoring ability is highly promising for cancer theranostics in clinical trials.