原油计量交接中K值的计算

对原油计量交接中遇到的K值特殊情况下的查表问题展开讨论，综合了《数值修约规则》及《石油计量表》等标准，提出切实可行的解决办法，满足了生产现场的需要。     

浅析数值修约在原油破乳剂闪点测试数据处理中的应用

根据闪点测定中数据精确度要求,以原油破乳剂测试为例,探讨了半个单位数值修约在闪点测试数据处理中的技术规则与应用实践,为规范实验室计量管理、提高油田化学助剂检测分析的科学性和准确度提供参考。     

基于齿廓修形的齿轮轴花键接触特性研究

齿轮轴花键广泛应用于大转矩传递,但在实际工作中易出现齿面损伤问题。考虑齿轮轴花键的变载荷工况和花键齿的非线性接触特性,建立齿轮轴花键接触应力刚度有限元求解模型,提出利用仿真数据计算花键齿接触应力和刚度的计算方法,并研究齿轮轴花键齿廓修形对花键齿接触应力和刚度的影响规律。研究结果表明,齿廓修形0.02 mm下接触应力降低约6%,齿廓修形改善了齿轮轴花键接触应力,有助于提升花键工作性能。     

钛合金中氧氮含量测量不确定度评定研究

文章依据GB/T 4698.7—2011化学仪器分析红外、热导法对钛合金氧氮含量进行测试,采用GUM方法对TC4合金中氧氮含量进行不确定度评定,分别从试样的均匀性、环境、仪器校准、仪器分辨率、化学标准物质、数值修约等方面进行评定。结果显示仪器校准及标准物质为影响氧氮不确定度评定的主要影响因素。在K=2,置信概率为95%的情况下,氧的扩展不确定度为0.01%,氮的扩展不确定度为0.002%。     

设备大项修、预修立项审定方法探析

根据设备大项修、预修的定义和特点,结合陕西重型汽车有限公司近年来设备大项修立项实施过程发现的一些问题,从多个角度对设备大项修立项时应该关注的维度进行分析,运用多种方法对大项修立项的判别和准则给出了条件解释,在降低成本的同时促进资产的保值增值,以更好地做好大项修工作。     

我们是如何进行机械动力设备修制改革的

北京铁路局拥有金切、动力、电气、起重运输、工程机械、木工铸工等10大类机械动力设备37801台,价值11 857.36万元,是铁路运输生产不可缺少的重要组成部分。这些设备每年需要的维修费约5000万元。做好设备维修管理工作是保证安全运输的基础。 多少年来,机械动力设备的修理工作一直沿用苏联的计划预修制,实践证明,这种修制很不适应科技日益发展的现代设备状况。从设备大、中、小修的数量来看,一方面有80％左右本来可以不修而进行了修理的     

油田水平井修井工艺技术分析

本文主要对水平井修井技术的基本情况以及各项水平井修井技术进行了深入分析,接着笔者依据自身经验,对辽河油田水平井修井工艺技术的应用进行了探讨,并提出合理化建议,供以借鉴。     

钢管修磨机气动回路的改进

我厂从西德引进了管子外表面修磨机(图1),修磨时,修磨轮向下,压在管子的表面上。为使修磨轮上下摆动,采用气缸驱动,其气动回路如图2a 所示。在调试中发现,采用这种气动回路,存在如下问题:1.修磨轮向下困难,气缸推力太小;2.电磁阀得电后,气缸动作最初反应缓慢,但过一定位置,修磨轮会突然向下加速,重重地落在管子表面上,撞断修磨带;3.修磨的法向压力无法调节,不能满足修磨的     

公英制单位换算中尺寸及尺寸公差的修约问题探讨

提出在英制单位转换为公制单位时,其修约问题应以工程中使用的"精度”或"误差”的概念为主来进行转换,而非纯数学的换算,这样既便于加工、装配中的测量,又不降低零件的精度.     

论井下作业修井技术现状及新工艺优化研究

油田企业之所以进行井下修井作业,主要是为了保证能够获取较高的采油率,促进采油工作及时有效的开展。当前,与国外油田企业先进完善的井下作业修井技术相比,国内各油田采用的井下作业修井技术还有待进一步提高。本文以国内油田井下作业修井技术现状为切入点,对油田井下作业修井技术新工艺的优化进行了一番分析研究。     

Do firms leverage the FDA nutrient label rounding rules to generate favorable nutrition fact panels or health claims?

The increasing incidence of nutrition related health concerns has made food labeling an important policy issue. Previous work suggests the importance of communicating nutrition information to consumers through product packaging. This paper investigates the role of labeling guidelines, which allow the rounding of calorie and nutrient levels on nutrition fact panels and affects front of package claims. We examine ready-to-eat cereal products as a bundle of nutrient attributes, and estimate the likelihood and magnitude of the rounding of specific nutrients and calories. We find systematic rounding, both up and down, of several nutrients, which affects allowable health claims and may influence consumer product choice and health outcomes.     

The amenity value of natural views

We estimate nonmarket values for natural views in an urban setting. These views contain the aesthetics of natural areas commonly found in public parks and open space, and offer an aspect of property valuation that previous research is unable to disentangle from proximity to parks and open space. We incorporate machine learning techniques on Google Street View images to identify natural views in an urban setting. We find positive capitalization rates associated with household views of park-like properties. Estimates are robust to a variety of specifications, including models that are identified off of new developments on neighboring properties and falsification tests that help to rule out the effect of a broader neighborhood environment. From a policy perspective, our results inform as to the optimal size, location, and shape of open space. Furthermore, machine learning methods used in the construction of our view variable provide a potentially powerful tool for other nonmarket valuation studies.     

Why Do We Have Urban Density Controls?

Almost all urban land use controls reduce permitted densities. This article analyzes restrictions on residential densities in a conventional model of density–distance functions. Density controls force development to extend farther than in competitive equilibrium, thus increasing commuting distances and dwelling costs. Residents benefit if, as is likely, they prefer lower densities than in competitive equilibrium. But there is a limit to the extra commuting and housing costs that nevertheless make residents better off. Theoretical and numerical analyses are presented to show that likely parameter values almost certainly result in reductions in residents' welfare.     

The Impact of Initial-Year Discounts on ARM Prepayments

This study uses new data on the rate of prepayment on conventional single-family adjustable-rate mortgages (ARMs) that originated between 1983 and 1986 to determine if ARMs with and without initial-year discounts have the same probability of paying off. The new data are from a large national private mortgage insurer in the United States. Each loan is tracked from its origination date through prepayment or the end of 1991. Nonparametric test statistics are used to test for differences in these prepayment rates. The findings suggest that ARMs with initial-year discounts are paid off at a rate that is essentially no different from the rate on otherwise comparable ARMs without initial-year discounts.     

Bill-and-Keep peering

Peering arrangements between Internet Service Providers (ISPs), in which providers agree to carry traffic originating from a peer, are common in the Internet. A common contractual peering agreement between smaller ISPs is “Bill-and-Keep”, where no money changes hands between the peers. This paper first investigates a situation when ISPs who have access to a transit ISP capable of handling their traffic for a fee, decide to peer incurring some fixed peering cost. Using a simple model it is shown that Bill-and-Keep peering is the fair and efficient outcome if the transit ISP charges for both inbound and outbound traffic and transit charges as well as costs of peering are symmetric. Next, complementarity between providers at the operational level, as measured by improvement in quality of service (QoS), is analyzed using an idealized model. Assuming that each provider incurs costs, or degradation in QoS, from its traffic traversing its own as well as the peer's links and chooses the amount of traffic to send on its peers’ links in its self-interest, the Nash equilibria of the resulting one shot game and then of an infinitely repeated game are analyzed. For the one-shot game, it is established that, while it is not possible for all the providers to be worse off, it is certainly possible for all of them to be better off. An intuitive sufficient condition for each of the providers to be better off in Nash equilibrium is then derived. Further, it is shown that providers that are better off in the one-shot game can cooperate using threat strategies in an infinitely repeated game and can each be even better off. Coalition formation between peers as a dynamic process is also investigated and some examples and conjectures on some preliminary findings are provided. Finally, the policy implications of the findings are discussed.     

Complementarities and competition: Unpacking the drivers of entrants' technology choices in the solar photovoltaic industry

Entrants in new industries pursue distinct technologies in hopes of winning the technology competition and achieving sustainable competitive advantage. We draw on the complementary assets framework to predict entrants' technology choices in an emerging industry. Evidence from the global solar photovoltaic industry supports our arguments that entrants are more likely to choose technologies with higher technical performance and for which key complementary assets are available in the ecosystem. However, diversifying entrants are more likely to trade off superior performance for complementary asset availability whereas start‐up entrants are more likely to trade off complementary asset availability for superior performance. This difference is largely due to diversifying entrants with pre‐entry capabilities related to the industry. The study offers a novel illustration of how complementarities and competition shape entry strategies. Copyright © 2013 John Wiley & Sons, Ltd.     

Who’s Displaced First? The Role of Race in Layoff Decisions

We test empirically the proposition that race significantly affects an employee's layoff chances. Using data from a financial firm (N = 8918), we find that whites are less likely to be laid off than nonwhites and that, among nonwhites, Asians are less likely to be laid off than blacks or Hispanics. These findings are statistically significant after controlling for structural factors (business unit, occupation, and job level) and individual characteristics (tenure and performance rating). A similar pattern of racial differences exists in other employment practices more actively monitored by the firm, including promotions, pay raises, and performance ratings. Yet these differences are smaller than those in layoffs and are significant for blacks only, not for Hispanics. Our findings suggest that monitoring personnel decisions can reduce racial inequality. Furthermore, our findings highlight that racial differences in employment outcomes vary among minority groups.     

A Dynamic Model of Auctions with Buy‐It‐Now: Theory and Evidence

In the ascending‐price auctions with Yahoo!‐type buy‐it‐now (BIN), we characterize and derive the closed‐form solution for the optimal bidding strategy of the bidders and the optimal BIN price of the seller when they are both risk‐averse. The seller is shown to be strictly better off with the BIN option, while the bidders are better off only when their valuation is high enough. The theory also implies that the expected transaction price is higher in an auction with an optimal BIN price than one without a BIN option. This prediction is confirmed by our data collected from Taiwan's Yahoo! auctions.     

Examining the performance effects of post spin‐off links to parent firms: should the apron strings be cut?

Little research has examined the performance implications of the parent‐child relationship post spin‐off. Although the parent provided oversight of the child prior to the spin‐off, effects of post spin‐off links to the child remain unclear. Applying transaction cost and agency theories, our study of 142 firms spun‐off between 1986 and 1997 examines how oversight and ownership by the parent firm influence stock market performance post spin‐off. We find that while child firms benefit from some links to the parent, having too many links is negatively related to performance. The findings suggest that there is a balance between having too much parental involvement and not enough. Our study extends understanding of post spin‐off child firm performance and provides valuable insights for both parent and child firms. Copyright © 2011 John Wiley & Sons, Ltd.     

Creating University Spin‐Offs: A Science‐Based Design Perspective*

Academic entrepreneurship by means of university spin‐offs commercializes technological breakthroughs, which may otherwise remain unexploited. However, many universities face difficulties in creating spin‐offs. This article adopts a science‐based design approach to connect scholarly research with the pragmatics of effectively creating university spin‐offs. This approach serves to link the practice of university spin‐off creation, via design principles, to the scholarly knowledge in this area. As such, science‐based design promotes the interplay between emergent and deliberate design processes. This framework is used to develop a set of design principles that are practice based as well as grounded in the existing body of research on university spin‐offs. A case‐study of spin‐off creation at a Dutch university illustrates the interplay between initial processes characterized by emergent design and the subsequent process that was more deliberate in nature. This case study also suggests there are two fundamentally different phases in building capacity for university spin‐off creation. First, an infrastructure for spin‐off creation (including a collaborative network of investors, managers and advisors) is developed that then enables support activities to individual spin‐off ventures. This study concludes that to build and increase capacity for creating spin‐offs, universities should do the following: (1) create university‐wide awareness of entrepreneurship opportunities, stimulate the development of entrepreneurial ideas, and subsequently screen entrepreneurs and ideas by programs targeted at students and academic staff; (2) support start‐up teams in composing and learning the right mix of venturing skills and knowledge by providing access to advice, coaching, and training; (3) help starters in obtaining access to resources and developing their social capital by creating a collaborative network organization of investors, managers, and advisors; (4) set clear and supportive rules and procedures that regulate the university spin‐off process, enhance fair treatment of involved parties, and separate spin‐off processes from academic research and teaching; and (5) shape a university culture that reinforces academic entrepreneurship by creating norms and exemplars that motivate entrepreneurial behavior. These and other results of this study illustrate how science‐based design can connect scholarly research to the pragmatics of actually creating spin‐offs in academic institutions.