Effects of unbalance location on dynamic characteristics of high-speed gasoline engine turbocharger with floating ring bearings

For the high-speed gasoline engine turbocharger rotor, due to the heterogeneity of multiple parts material, manufacturing and assembly errors, running wear in impeller and uneven carbon of turbine, the random unbalance usually can be developed which will induce excessive rotor vibration, and even lead to nonlinear vibration accidents. However, the investigation of unbalance location on the nonlinear high-speed turbocharger rotordynamic characteristics is less. In order to discuss the rotor unbalance location effects of turbocharger with nonlinear floating ring bearings(FRBs), the realistic turbocharger of gasoline engine is taken as a research object. The rotordynamic equations of motion under the condition of unbalance are derived by applied unbalance force and nonlinear oil film force of FRBs. The FE model of turbocharger rotor-bearing system is modeled which includes the unbalance excitation and nonlinear FRBs. Under the conditions of four different applied locations of unbalance, the nonlinear transient analyses are performed based on the rotor FEM. The differences of dynamic behavior are obvious to the turbocharger rotor systems for four conditions, and the bifurcation phenomena are different. From the results of waterfall and transient response analysis, the speed for the appearance of fractional frequency is not identical and the amplitude magnitude is different from the different unbalance locations, and the non-synchronous vibration does not occur in the turbocharger and the amplitude is relative stable and minimum under the condition 4. The turbocharger vibration and non-synchronous components could be reduced or suppressed by controlling the applied location of unbalance, which is helpful for the dynamic design, fault diagnosis and vibration control of the high-speed gasoline engine turbochargers.     

某大型瀑布设计方案的选择研究

根据某工程的实际情况,提出四叠瀑和滑瀑两种瀑布方案,通过两种方案的瀑布构造、堰上水头、设计单宽流量和循环水泵选型的比较,得出了滑瀑方案更合适、能耗更小的结论。     

Obituary: Richard D. Walk (1920-1999).

Memorializes Richard D. Walk, known for his work with Eleanor Gibson on the visual cliff and the development of depth perception. His research interests and contributions were diverse and included visual discrimination, research on concept formation, aesthetics, and social relations. He is best known for his work on perceptual development, and his 1981 book Perceptual Development still provides an excellent introduction and guide to the field. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

快速以太网的网络瓶颈分析

通过对计算机网络系统中瓶颈产生的基本原理的讨论 ,分析了快速以太网在实现过程中可能存在的网络瓶颈 ,并给出了解决由此而产生的网络拥塞的基本策略     

采用灰色码观测的量子进化算法

针对传统量子进化算法采用二进制观测机制,导致量子波动幅度较大且连续观测到相邻实数概率低的问题,本文提出了一种采用灰色码观测机制的量子进化算法.由于量子擅长全局搜索,灰色码擅长局部搜索,因此所提出的算法能较好平衡勘探和开采能力,量子进化更加平滑和高效.通过实验表明,算法能有效避免早熟和局部极值等问题,算法的精度更高,收敛速度更快.     

A Process Programmer Looks at the Spiral Model: A Tribute to the Deep Insights of Barry W. Boehm

This paper elaborates on implications of Barry W. Boehm''s Spiral Model of software development. The paper notes that the Spiral Model presents a compelling view of software development, evocatively represented by a visual image that appeals strongly to intuition, and notes that the view and image have motivated and justified a range of important views of how software development should be done. This paper enhances and elaborates on the intuitions by supplementing them with a definition of the Spiral Model that is enunciated in terms of a rigorously defined language. The rigorous enunciation and accompanying alternative visual depiction are then used to provide clarification and formalization of some of the clearly-indicated elaborations of the Spiral Model. Both the Waterfall Model of software development and the Scrum agile method are presented as possible elaborations of the Spiral Model. Still other elaborations are indicated. Similarities in the visualizations of these development approaches suggest some underlying similarities in the approaches themselves, suggesting the potential value of effective process visualizations. The breadth of these elaborations is also used to suggest how the Spiral Model seems to provide a strong focus on some of the quintessential aspects of what comprises effective software development.     

基于双瀑布软件过程模型实现软件质量工程

针对高质量软件开发的需求，通过对软件性能工程使用范围受限和应用复杂等方面问题的分析，在综合多种传统软件过程模型特点的基础上，提出 了一种将软件质量属性建模、分析和反馈融入软件过程的双瀑布软件过程模型，并详细介绍了双瀑布模型在软件过程中各个阶段的任务，重点说明了其改进及引入的建模样式、建模知识库等技术.     

基于双瀑布软件过程模型实现软件质量工程

针对高质量软件开发的需求，通过对软件性能工程使用范围受限和应用复杂等方面问题的分析，在综合多种传统软件过程模型特点的基础上，提出 了一种将软件质量属性建模、分析和反馈融入软件过程的双瀑布软件过程模型，并详细介绍了双瀑布模型在软件过程中各个阶段的任务，重点说明了其改进及引入的建模样式、建模知识库等技术.     

软件净室技术在大型软件开发中的应用

以CWTCAD软件为例 ,介绍如何将软件净室技术应用于软件的质量管理。