Beyond Boundary Objects: Collaborative Reuse in Aircraft Technical Support

Boundary objects are a critical, but understudied, theoretical construct in CSCW. Through a field study of aircraft technical support, we examined the role of boundary objects in the practical achievement of safety by service engineers. Their resolution of repair requests was preserved in the organization’s memory via three compound boundary objects. These crystallizations did not manifest a static interpretation, but instead were continually reinterpreted in light of meta-negotiations. This suggests design implications for organizational memory systems which can more fluidly represent the meta-negotiations surrounding boundary objects.     

Coordinating production and distribution of jobs with bundling operations

We consider an integrated scheduling and distribution model in which jobs completed by two different machines must be bundled together for delivery. The objective is to minimize the sum of the delivery cost and customers' waiting costs. Such a model not only attempts to coordinate the job schedules on both machines, but also aims to coordinate the machine schedules with the delivery plan. Polynomial-time heuristics and approximation schemes are developed for the model with only direct shipments as well as the general model with milk-run deliveries.     

Effect of Y2O3, CeO2 on Sintering Properties of Si3N4 Ceramics

The effect of rare earth oxides Y203 or Ce02 on sintering properties of Si3N4 ceramics was studied and the mechanism of assisting action during sintering was analyzed. The results in dicate that the best sintering properties appear in Si3N4 ceramics with 5% Y203 or 8% CeO2. Secondary crystallites are formed at grain boundaries after heat treatment,which decreases the amount of glass phase and contributes to the improvement of high-temperature mechanical properties of silicon nitride.     

多相平衡规律在树脂再生过程中的应用研究

借助于三相平衡体系的性能分析，提出了一步法复苏再生阴离子交换树脂的新思路，从而实现阴离子交换树脂的再生和有机污染去除的同步性．对三相再生体系的再生能力，循环再生能力和树脂的有机污染去除能力进行了研究，并进行了基本性能测试和理论分析．结果表明三相再生体系能够很好的保持再生和循环再生效果，缓解了树脂的有机污染，一步复苏再生法具有理论可行性。     

The incompatibility of knowledge regimes: consequences of the material world for cross-domain work

In this paper, we argue that successful integration of knowledge across work domains in the short-term can mask the generation of long-term consequences. We explore a setting, the introduction of environmental considerations into semiconductor manufacturing, where the eventual adoption of common measurement artifacts and associated practices enabled knowledge integration, but failed to address significant underlying consequences. Drawing from observational, interview, and archival data we develop an understanding of the work practices of the Tech and EnviroTech groups as structured by the material world and broader collective conventions. We introduce the concept of knowledge regime to outline the differences in knowledge across these work domains. More specifically, we find that differences in the causal specificity and developmental time horizon of knowledge and the measurement artifacts that result contribute to the relative power of one knowledge regime over another. Understanding these sources of incompatibility provides insight into the design requirements of information systems as boundary objects for knowledge integration, but also specifies the potential limits to any design effort.     

1/3码的动态CMOS全自检电路的设计

自检测电路设计方法有多种多样,本文中介绍了TSC电路的概念,并采用1/3码的动态CMOS设计TSC电路,通过在Cadence环境下仿真,仿真结果表明本设计可行。     

Object data MODEL = object-oriented + semantic models

The term ‘object-oriented database’ has been used to refer to different characteristics and mechanisms supported by semantic databases and (behaviorally) object-oriented ones. While this indicates the current confusion due to the lack of a common model, it also suggests the potential desirability of combining these two kinds of modeling facilities into the same nutshell. This paper summarizes from these two paradigms the features common to both, the features influenced/adopted by each other, and the features which are presented in one paradigm but missing from the other. After a brief analysis and discussion of these features, we conclude this paper by proposing our major theme: a complete object data model should take the union of the facilities offered by these two kinds of models.     

岭澳核电工程38m平台边坡处理

岭澳核电重件道路施工中所遇到的38m的观景平台在大亚湾核电站占有重要地位,在工程施工中发现边坡坡体陡峭,无法达到规范规定的稳定要求,故采取了加固措施。采用抗滑稳定计算的分析方法,对边坡加固的必要性及实施加固后的稳定性进行了分析。     

Performance analysis of two-branch transmit diversity block-coded OFDM systems in time-varying multipath Rayleigh-fading channels

Based on Alamouti code, Lee and Williams proposed two-branch transmit diversity block-coded orthogonal frequency-division multiplexing (TDBC-OFDM) systems, namely, space-time block-coded OFDM (STBC-OFDM) and space-frequency block-coded OFDM (SFBC-OFDM). However, they employed the simple maximum-likelihood (SML) detector, which was designed under the assumption that the channel is static over the duration of a space-time/frequency codeword. Therefore, STBC-OFDM/SFBC-OFDM suffers from the high time/frequency selectivity of the wireless mobile fading channel. In this paper, besides the original SML detector, three detectors proposed by Vielmon et al. are applied to improve the two-branch TDBC-OFDM systems. Additionally, assuming sufficient cyclic prefix, the performances of all systems in spatially uncorrelated time-varying multipath Rayleigh-fading channels are evaluated by theoretical derivation and computer simulation, as well. According to the derived bit-error rate (BER), we further derive the bit-error outage (BEO) to provide a more object judgment on the transmission quality within a fading environment. Numerical results have revealed that significant performance improvement can be achieved even when the systems are operated in highly selective channels.