Towards intelligent dressing

The aim of this article is to state the principles of an intelligent monitoring and control system for the grinding machine, comprising the dressing process as well as grinding stability.     

A medium-access control protocol for a cellular packet CDMAcarrying multirate traffic

We propose and evaluate a medium-access control (MAC) protocol for synchronous cellular packet direct-sequence code-division multiple-access (DS/CDMA). The protocol is designed for handling a variety of multimedia traffic types in an integrated wireless-access network (IWAN). For instance, the protocol is suited for carrying multiple traffic types of different priorities. An analytical model for the equilibrium state has been developed for the proposed protocol. A comparative evaluation of the protocol is done for three different radio frequency bandwidths currently under consideration for personal communication services (PCS), i.e., 1.25 MHz, 5 MHz, and 10 MHz. Our results demonstrate that the proposed protocol is both robust and flexible for the intended IWAN applications. It offers a significant multiplexing gain as the bandwidth increases     

具有阻力特性材料的σ_f－σ关系及一种新的阻力曲线测定方法

通过对相变增韧陶瓷及一种可切削玻璃－陶瓷动态疲劳（恒应力速率）试验中高应力速率区断裂应力下降现象的理论分析，发现这种现象与材料的阻力特性（Ｒ－ｃｕｒｖｅ）密切相关。确立的σ_ｆ－σ理论关系能够很好地描述整个应力速率区间内的动态疲劳试验结果。高应力速率区σ_ｆ－σ在双对数坐标下为负斜率直线，直线斜率为（ｍ为阻力曲线ＫＲ＝ｋ（△ａ）~ｍ的指数），断裂主要由材料阻力行为控制；低应力速率区，σ_ｆ－σ在双对数坐标下为正斜率直线，直线斜率为　（ｎ为应力腐蚀指数），断裂主要由材料应力腐蚀行为控制。建立了测定材料阻力特性的一种新方法，分别用这种方法及压痕／弯曲方法对一种可切削玻璃－陶瓷的阻力特性进行了实验测定，两种方法所得结果有很好的一致性。     

Densification involved in the UV-based photosensitivity of silicaglasses and optical fibers

A comprehensive survey of photosensitivity in silica glasses and optical fiber is reviewed. Recent work on understanding the mechanisms contributing to germanium or aluminum doped fiber photosensitivity is discussed within the framework of photoelastic densification models     

Evaluating the impact of CASE: an empirical comparison of retrospective and cross-sectional survey approaches

The purpose of this paper is to evaluate two methods of assessing the productivity and quality impact of Computer Aided Software Engineering (CASE) and Fourth Generation Language (4GL) technologies: (1) by the retrospective method; and (2) the cross-sectional method. Both methods involve the use of questionnaire surveys. Developers' perceptions depend on the context in which they are expressed and this includes expectations about the effectiveness of a given software product. Consequently, it is generally not reliable to base inferences about the relative merits of CASE and 4GLs on a cross-sectional comparison of two separate samples of users. The retrospective method that requires each respondent to directly compare different products is shown to be more reliable. However, there may be scope to employ cross-sectional comparisons of the findings from different samples where both sets of respondents use the same reference point for their judgements, and where numerical rather than verbal rating scales are used to measure perceptions.     

The Solutions for Adjustment and Reconstruction of Water-Drive Surface Systems in the Old Areas of Daqing Oilfield

Introduction 　　Owing to long-time running, more facilities including stations, pipelines, vessels have become corrosive and aged ,some process has grown old, it has exert more burden for the maintenance and repair.Simultaneously, the fluid production rate, oil production rate and water injection rate has changed greatly so that the inflicts and problems from the established surface systems will become more obvious. Energy cost of production and running has increasing continuously. Capacity has been unbalance in systems and areas. 　　……