再论自发过程及热力学过程判据

自发过程是热力学的一个重要概念,它与热力学第二定律相结合可指明过程的方向,然而到目前为止自发过程还没有一个令人满意的定义,给物理化学教学带来了困难。为了解决此问题,针对公认的自发过程的例子进行了严格分析和总结,在此基础上指出了目前典型的自发过程定义存在的问题,指明这些问题是由人们在讨论自发过程例子时没有注意系统的划分而导致的。给出了意义明确的自发过程定义,引出了给定条件下能发生的非自发过程的概念。将这些概念和热力学第二定律相结合,得到方便实用的过程方向判据,克服了以往自发过程定义的模糊性。     

对普通物理学中功定义的商榷

本文对三种功的定义,和由此产生的困惑进行了分析,并明确了功的最佳定义。     

建设项目经济评价中的销售(营业)价格判据——兼论一种新的更完善的定价策略

一、综合销售(营业)价格(P_c~t) 1.综合销售(营业)价格(P_c~t)的定义 任何建设项目都以向社会提供一定数量的产品(服务)为目的。因此,每一个建设项目(不含房地产开发项目,下同)在其生产经营期(含投产期和达产期)内的任何一年,总存在一个综合销售(营业)价格(P_c~t),使下式成立: S~t=:P_c~tQ~t 或:P_c~t=S~t/Q~t………………………………………………………………………………① 其中:S~t——项目每t年的总产出,即总销售(营业)收入。 P_c~t——项目第t年的综合销售(营业)价格。     

功图计量误差原因分析及对策探讨

本文通过查阅文献及深入分析功图计量原理,得出影响功图计量准确度的3个主要因素-柱塞的有效冲程Spc泵的漏失量△Q、泵排出压力下的油水混合物的体积系数B,并通过选用W地区F采油作业区X14、X7、X3、X16增压站这4个站点某一天的实际产液量与功图计量液量之和进行对比分析,对这3个主要因素的影响程度进行了定量分析,求解出了这3个影响因素的具体误差值或者计算公式.     

油气资产定义的探讨

油气资产对于石油开采企业意义重大，但是国内外尚没有对这一关键概念的完整定义，文章从理论界和实务界对油气资产的界定入手，经过对比分析，得出油气资产的定义，并将油气资产划分为油气储量资产和非储量油气资产，阐述了这两类油气资产之间的联系与区别。     

积分定义及对称性

本文给出了线、面、体积分定义的一般描述,并导出了利用对称性简化积分计算的定理。     

油井"功图法"计量监测系统应用及评价

通过对“功图法”计量监测系统原理、组成、实现功能的描述以及对其在安塞油田的应用评价．证明“功图法”计量监测系统测试的油井产液量值与实际单量值趋于吻合,能够反映油井的实际产液能力,满足油井计量的精度要求．为今后油田油井计量提供一个新途径．     

油井产量计量的功图法技术及误差分析

油井计量采用的双容积单量方法．增加了地面建设的投资和运行成本，而且站内多井计量时很难及时进行油井产量的计量。针对这种实际情况，采用井口传感器记录抽油杆载荷与位移随时间变化的数据信息，确定出泵的有效冲程，再由固化在仪器内的数学模型求得油井产量。该计量技术通过长庆油田24口井的实际应用，取得了较好的效果。由不同产量下的测试误差分析可知，油井产量越高，测试结果越准确，对产量大于10m^3／d的油井，平均误差仅4．3％。     

会计准则及税收政策对固定资产的不同定义

<正>《会计准则第4号—固定资产》规定,固定资产是指同时具有下列特征的有形资产:为生产商品、提供劳务、出租或经营管理而持有的;使用寿命超过一个会计年度。同时指出,作为投资性房地产的建筑物以及生产性生物资产不属于固定资产。     

在线体积管匹配原油流量计及流量计系数交接

体积管容积与流量计不匹配会导致流量计栓定重复性超差现象;分组标定方式可改善流量计重复性评价结果,但其科学性需商榷。只要流量计重复性、线性合格,用流量计系数代替器差调整器是可行选择;采用系数消除流量计系统误差,力求交接误差趋于零。     

基于工作过程的《染色实训》课程设计

通过对印染行业岗位群能力分析、典型工作任务归纳导出《染色实训》这门课程,按照工作过程系统化的思想,以印染加工的对象"纺织材料"为载体,进行了目标设计、教学方案设计,并讨论了课程评价方式。     

基于六西格玛的软件过程缺陷管理方法模型与应用

软件产品的质量出自于软件设计过程,持续优化的软件过程管理方法能使软件过程产生的软件缺陷处于受控状态.结合六西格玛管理思想,提出并建立基于六西格玛的软件过程缺陷管理方法模型,将有关的方法工具引入到相应的模型中,为软件过程缺陷管理提供更有效的解决方案.软件过程缺陷管理方法模型从质量度量的角度对软件开发过程进行设计与优化,对...     

Disconnecting labour: The impact of intraplatform algorithmic changes on the labour process and workers' capacity to organise collectively

This article examines how gig economy platform companies, via algorithmic management, shape working conditions and collective organisation of food delivery couriers. Using qualitative data from one case study operating in a city in the United Kingdom, the study captures real-time intraplatform unilateral changes in algorithmic management to provide increased flexibility for couriers. Findings show algorithmic changes generating a reconfigured, fragmented and compliant workforce. As a result, couriers demonstrate different interests and motivations to work for the company, where disparities in the demands for improved working conditions hindered efforts for collective organising. This article argues that intraplatform algorithmic changes create affordances that companies can exploit to concentrate power over labour even when conceding some control over the labour process.     

Navigating the new product development process

The quest for success in new product development (NPD) requires management to navigate complex processes. This study presents empirical evidence of the evaluative criteria used by well-experienced NPD managers from the UK and the Netherlands to control performance at different gates of the NPD process. The emerging usage patterns suggest that these criteria are aligned to the specific requirements of each stage in the process. This allows for detection of problems and initiation of adjustments that increase the chance for overall success of the new product. Based on these findings, recommendations are provided for managers to safeguard strategically the performance of their NPD efforts.     

Supply source selection criteria: The impact of supplier performance on distributor performance

In drawing attention to certain important gaps in the purchasing literature, the study reports on a systematic examination of supplier performance in purchasing decision criteria of U.K. distributor firms of information technology (IT) products. An attempt is made to explore the presence of dimensions underlying supplier performance in buying decision elements and identify potential differences in distributor performance with regard to supplier performance in important purchasing decision criteria. Based on a survey sample of 237 distributors, the results suggest significant differences between highly performing and poorly performing distributors in relation to their suppliers' performance in four buying decision criterion dimensions: reliability, competitive pricing, service support, and technological capability. The implications of the findings for business practitioners are highlighted, and directions for future research are identified.     

Supplier selection-order allocation: A two-stage multiple criteria dynamic programming approach

This paper proposes a two-stage multiple criteria dynamic programming approach for two of the most critical tasks in supply chain management, namely, supplier selection and order allocation. In the first stage, to address multiple decision criteria in supplier ranking, the analytic hierarchy process (AHP) is employed. In the second stage, supplier ranks are fed into an order allocation model that aims at maximizing a utility function for the firm as well as minimizing the total supply chain costs, subject to constraints on demand, capacity, and inventory levels. A dynamic programming approach is crafted to solve the proposed bi-objective model.     

Investigating the decision criteria used in electronic components procurement

Previous research has reported that the decision criteria used to evaluate suppliers differs by product category. Rather than investigating the “key buying criteria” across the entire gamut of products and services, this research takes a novel approach by investigating the evaluation criteria used in the procurement of component parts. The survey results suggest that the content and structure of the decision criteria used by business customers to assess their suppliers does not differ across an array of electronic components. The business implication is that business customers that formally track the performance of their suppliers along the critical evaluation criteria will be in a better position to gain a competitive advantage by effectively managing the inbound supply chain.     

The economic modeling of strategy process: ‘clean models’ and ‘dirty hands’

We argue that our model of learning in alliances ( Khanna, Gulati and Nohria, 1998 ) is an economic model of strategy process. We discuss implications of this view for the strategy process vs. content debate, for the appropriate testing of models of strategy process, and for the role of economics in helping understand strategy process. We propose that the ‘clean models’ from economics and ‘dirty hands’ of traditional process inquiries offer research designs that are complementary rather than incompatible ( Hirsch, Michaels and Friedman, 1987 ). Copyright © 2000 John Wiley & Sons, Ltd.