离心式压缩机干气密封工作原理与典型故障研究

文章首先介绍了离心式压缩机干气密封的工作原理,接着结合当前的离心式压缩机运行原理对离心式压缩机运转过程中发生的典型故障进行了分析,最后总结了离心式压缩机发生故障的原因,并对其原因进行讨论,以此为我国今后的压缩机运行及故障检测维修提供可行性参考。     

离心式压缩机振动故障分析与安全运行

由于离心式压缩机在能源工程中占据重要位置,一旦设备出现故障,将给能源化工工程带来巨大的损失。为保证能源化工行业施工的安全性,需要提升离心式压缩机的可靠性。文章介绍了离心式压缩机的结构、特性与离心式压缩机出现的震动故障,并对离心式压缩机的安全运行提出了合理化的解决措施。     

往复式天然气压缩机故障诊断方法探析

在油气田生产、天然气集输、天然气销售等方面,应用到的重要机械设备之一就是往复式压缩机组。文章从现阶段的往复压缩机诊断技术的研究现状入手,对当前往复式天然气压缩机组最常见的故障因素进行了分析,并提出了若干常见的故障诊断方法,以供机械维修技术人员参考。     

离心压缩机常见故障诊断与排除

文章针对离心式压缩机在启动、加载以及运行过程中经常出现的故障,分析了出现问题的各种原因,并提出了合理的处治措施,以确保压缩机的安全稳定运行。     

离心式压缩机空气过滤器改造分析

文章介绍了离心式压缩机空气过滤器存在的问题及压缩机的工作原理,阐述了自洁式空气过滤器的工作原理及其结构特点,进而对空气过滤器改造的可行性进行分析,并分析离心式压缩机空气过滤器改造后产生的效益。     

离心式压缩机空气过滤器改造分析

文章介绍了离心式压缩机空气过滤器存在的问题及压缩机的工作原理，阐述了自洁式空气过滤器的工作原理及其结构特点，进而对空气过滤器改造的可行性进行分析，并分析离心式压缩机空气过滤器改造后产生的效益。     

离心式压缩机的转速调节探讨

离心式压缩机是一种广泛应用的动力设备。在很多较大的企业生产单位都有应用。例如化工、冶金、机械制造等领域。而本文主要是通过对离心式压缩机转子、回流器的结构进行改良,来提高离心式压缩机的转速,以此来提高工作效率。     

基于有限元分析的离心式压缩机转子系统设计及性能优化

离心式压缩机作为一种用途广泛的能量转换装置,其制冷量大、结构简单、工作可靠、运行平稳以及效率高等特点,在许多行业中都占据了重要的地位。随着行业的不断发展,离心压缩机的输出冷量也越来越大,对离心式压缩机的设计要求也越来越高。转子系统作为离心压缩机的核心组件,对其性能的影响也是最重要的。文章以双级离心式压缩机转子系统为研究对象,在研究双级离心压缩机转子系统的构造、性能及其影响因素的基础上,采用了理论分析、仿真计算、优化设计和实验测试相结合的方法手段,对双级离心式压缩机转子系统进行了优化设计和研究,设计出了中央空调样机,并且通过了相关的测试实验。     

离心压缩机组状态监测故障诊断系统的开发

介绍离心压缩机组状态监测故障系统的总体结构、技术关键点及功能特点。系统以工业控制计算机为中心 ,实时监测机组轴向位置、轴承振动及工艺参数 (电流、功率、温度 )等信号 ,实现预警、紧急自动停车和滚动轴承故障诊断等功能。系统应用于工业现场 ,取得了良好的效果     

往复式压缩机故障诊断方法研究综述

压缩机是将原动机的动力转化成为气体压力能的机器,目前在石油、石化、化工等行业得到广泛应用,是工业生产的重要辅助设备,由于结构复杂、配件易损坏等,在使用过程中发生故障的频率较高。文章从对往复式压缩机故障诊断的现状出发,对其在生产过程中出现的故障及原因进行分析,并提出了相应的诊断方法。     

Incumplimiento del salario mínimo en Europa central y oriental

En este estudio se analiza el incumplimiento del salario mínimo durante el periodo 2003–2012 en diez países de Europa central y oriental con salario mínimo obligatorio nacional. A partir de los datos de EU‐SILC y la metodología propuesta por Bhorat, Kanbur y Mayet (2013), se cuantifica la incidencia y magnitud del incumplimiento. Se realizan análisis de regresión sobre determinantes individuales, laborales y macroeconómicos. Aunque la incidencia permanece relativamente baja, los trabajadores a los que se dirigen las políticas de salario mínimo parecen los más expuestos a su incumplimiento. Con el tiempo, una mayor incidencia se asocia a una razón más alta entre salario mínimo y salario medio.     

Value at Risk in the Suburbs: Eminent Domain and the Geographical Politics of the US Foreclosure Crisis

Several US counties and local governments have recently considered a novel solution to the foreclosure crisis. They plan to use eminent domain to compel the owners of mortgage debt—and specifically of private‐label mortgage‐backed securities—to sell the debt to the government at a price reflecting the loan's market value. The government would then restructure the debt and resell it to new investors. The plans are striking because—in contrast to both development‐driven eminent domain and the federal subprime bank bailout—they would force investors to assume asset devaluation and increased long‐term risk. Notably, the plans have emerged as an instance of financialization‐focused politics in suburbs and suburban cities of color, specifically majority‐black and ‐Latino/a suburbs. Local support for the plans, we argue, is rooted in the long‐term disinvestment of these ‘suburbs of exception', which became targets of subprime lending and eventually sites where the ‘financial exception' has been localized. But these demographic shifts, fragmentation and fiscal pressures have at the same time created a suburban political terrain in which the plans have gained their strongest political support.     

Towards a Theory of Serendipity: A Systematic Review and Conceptualization

Serendipity – the notion of making surprising and valuable discoveries – plays a major role in the success of individuals and organizations alike. Previous research has established the importance of serendipity and identified important individual- and organizational-level antecedents. However, the literature has been dispersed and the boundaries of the concept have been blurry, leading to a lack of conceptual clarity and structure, and thus limiting validity and managerial actionability. Based on a systematic literature review, I synthesize existing management-related research on serendipity and explicate the emergence and composition of serendipity in the organizational context. I first identify three necessary conditions that differentiate serendipity from related concepts such as luck or targeted innovation: agency, surprise, and value. Then, I draw from the literature on sensemaking, event-based theorizing, and quantum-based approaches to management to conceptualize the process of cultivating serendipity in the organizational context as a process of enabling potentiality and materialization, and develop a multi-level theory of (cultivating) serendipity. This conceptualization contributes to our collective understanding of how, why, and when (i.e., under what conditions) organizations can leverage the value in the unexpected, which opens up fruitful avenues for further research.     

Accountability of NGOs in Bangladesh A critical overview

NGOs in Bangladesh have been recognized as effective change agents in the socio-economic arena throughout the world. Their contributions in micro credit, non-formal education and primary health care are widely known. NGOs play a significant role in society. NGO accountability, as a result, has become a critical issue. NGO accountability in Bangladesh has been examined here in relation to patrons, clients and themselves. Of the three relationships only accountability to patrons is in a near satisfactory state. Accountability to clients is handicapped by lack of opportunities of beneficiaries to participate meaningfully in NGO policy making. Accountability to themselves is adversely affected due to the adherence to a strictly hierarchical system and the influence of founding and charismatic NGO leaders.     

Towards an Asian model of human resource management? A comparative analysis of China,Japan and South Korea

There has been much discussion regarding the possible decline and weakening of national systems of human resource management (HRM). Yet, culture and institutions are often cited as the major stumbling blocks to this outcome. Such constraints may dissipate in the analysis, particularly if ‘regional clusters’ are considered where geographic and cultural closeness and ‘openness’ to similar economic pressures exist. In such cases, it might be postulated that convergence in HRM will occur. We argue that China, Japan and South Korea represent such a cluster. This article examines these countries, to see if a degree of convergence is taking place and if it is towards an identifiable ‘Asian’ model of HRM. A model of change is presented that distinguishes between levels of occurrence and acceptance. Details of the development and practice of HRM in each country are then set out. The article ends with a discussion and implications section and a brief conclusion.     

Cultural Economy Planning in Creative Cities: Discourse and Practice

While a growing body of research analyses the functional mechanisms of the cultural or creative economy, there has been little attention devoted to understanding how local governments translate this work into policy. Moreover, research in this vein focuses predominately on Richard Florida's creative class thesis rather than considering the wider body of work that may influence policy. This article seeks to develop a deeper understanding of how municipalities conceptualize and plan for the cultural economy through the lens of two cities held up as model ‘creative cities’ — Austin, Texas and Toronto, Ontario. The work pays particular attention to how the cities adopt and adapt leading theories, strategies and discourses of the cultural economy. While policy documents indicate that the cities embrace the creative city model, in practice agencies tend to adapt conventional economic development strategies for cultural economy activity and appropriate the language of the creative city for multiple purposes.     

Input/output ranges and performance: an examination of US machine tool producers

Despite the establishment of high-tech multinational enterprises (MNEs) in Ireland since the late 1950s, the country did not succeed in closing the technological gap with most of its EU counterparts. The weak National System of Innovation (NSI), and in particular low business and government R&D levels, combined with a lack of research and technology linkages between MNEs and indigenous firms, explain these poor results. However, the Shannon region in the West of the country presents some specific institutional characteristics that could theoretically make the region a strong technological enclave. The various actors in the region - i.e. the administrative, financial, political and research institutions, as well as the business organizations - have indeed infused a new type of economic development. After a brief review of the available concepts and models articulated around these actors and their interrelationships, the paper analyses whether the Shannon region, taken as an illustrative example, mirrors a specific economic and technological localized setting. The study is based on a survey of indigenous and foreign firms.     

Sixty years of discrimination and diversity research in human resource management: A review with suggestions for future research directions

This article reviews discrimination and diversity research published in Human Resource Management (HRM) over the past 60 years. While discrimination and diversity are very different constructs, it is often informative to study them together, because when people recognize each other's diversity, this can result in bias, stereotyping, and discrimination. We conducted bibliographic searches for terms related to discrimination and diversity as well as a manual search through every title and abstract published in HRM over the last 60 years to assess article relevance. The search resulted in 135 research articles with 136 unique studies (i.e., samples) which are reviewed in this article. Sex and race are the demographics that have been examined the most in HRM, while religion has been examined the least. Moreover, the number of studies examining lesbian, gay, bisexual, transgender, and queer (LGBTQ) employees in the workplace in HRM has grown quickly within the past 10 years, culminating in a recent meta‐analysis. Our review looks at some of the earliest research published, the most recent research published, and the overall trends we identified in the research over the years for both discrimination and diversity articles. We then make future research suggestions and recommendations to advance the study of discrimination and diversity in the coming years.     

Multinomial distributions applied to random sampling of particulate materials

When sampling a batch consisting of particulate material, the distribution of a sample estimator can be characterized using knowledge about the sample drawing process. With Bernoulli sampling, the number of particles in the sample is binomially distributed. Because this is rarely realized in practice, we propose a sampling design in which the possible samples have a nearly equal mass. Expected values and variances of the sample estimator are calculated. It is shown that the sample estimator becomes identical to the Horvitz–Thompson estimator in the case of a large batch-to-sample mass ratio and a large sample mass. Simulations and experiments were performed to test the theory. Simulations confirm that the round-off error due to the discrete nature of particles is negligible for large sample sizes. Sampling experiments were carried out with a mixture of PolyPropylene (PP) and PolyTetraFluorEthylene (PTFE) spheres suspended in a viscous medium. The measured and theoretical variations are in good agreement.     

The Early History of the Cumulants and the Gram-Charlier Series

The early history of the Gram-Charlier series is discussed from three points of view: (1) a generalization of Laplace's central limit theorem, (2) a least squares approximation to a continuous function by means of Chebyshev-Hermite polynomials, (3) a generalization of Gauss's normal distribution to a system of skew distributions. Thiele defined the cumulants in terms of the moments, first by a recursion formula and later by an expansion of the logarithm of the moment generating function. He devised a differential operator which adjusts any cumulant to a desired value. His little known 1899 paper in Danish on the properties of the cumulants is translated into English in the Appendix.