An analytical expression for the power coefficient of an ideal horizontal-axis wind turbine

The paper shows that an analytical evaluation of the power coefficient C_p for an ideal horizontal-axis wind turbine can be made via an expression giving the direct relationship of C_p and the axial induction factor a. The results obtained agree closely with those obtained numerically from the usual integral expression involving several variables.     

Calculated hardenability for improved consistency of properties in heat treatable engineering steels

Hardenability is one of the most important parameters controlling the heat treated properties of engineering steels. It affects the consistency of response for microstructure, hardness, strength, toughness, and dimensional change (distortion). This study illustrates that a major benefit of controlling hardenability is improving the consistency of dimensional distortion resulting from heat treatment. To facilitate the supply of steels to hardenability limits, especially restricted hardenability, a new technique was developed for the prediction of Jominy hardenability from chemical composition. The technique, termed the “Database Method,” uses measured Jominy hardenability and chemical composition data, contained in a database, to calculate the hardenability for a query composition. Using up to ten known steels, selected from the database with compositions closely matching that of the query steel, a small adjustment is made to the measured hardenability of each known steel allowing for the small difference in composition between the query and chosen steel. The final calculated result for the query steel is taken as the average of the various estimates. The basis of the Database Method is explained, and the advantages are illustrated for selecting engineering grades.     

可组合的描述符泄露类型检查

应用程序通过操作系统的系统调用对文件描述符进行操作并管理文件资源。如果应用程序对资源描述符的管理出现错误并发生描述符泄漏,会严重影响系统的可用性。据此,提出了一种检查程序是否会导致描述符泄漏的类型系统,给出了描述符操作方法的语义和类型约束,证明了类型系统的可靠性定理。此外,还初步讨论了该类型系统在并发程序下的扩展。     

几种主流编程语言的特点与比较

计算机编程语言种类很多,但仅有少数几种语言得到了比较广泛的应用。本文选择了C语言、VB、VB．NET和Java作为讨论对象,首先总结比较了它们的数据类型、控制语句的语法,然后对编码规则的细节进行了阐述,最后讨论了这几门语言的技术性能特点。     

Confidence intervals for dependent data: Equating non-overlap with statistical significance

We revisit the problem of determining confidence interval widths for the comparison of means. For the independent two-sample (two-sided) case, Goldstein and Healy (1995) draw attention to the fact that comparisons based on 95% error bars are not very effective in assessing the statistical significance of the difference in means and derive the correct confidence interval for such a comparison. We provide an extension to Goldstein and Healy (1995) to account for the correlation structure and unequal variances. We use the results to develop rules of thumb for evaluating differences, in an exploratory manner, like Moses (1987) and Cumming (2009), from the independent case. We illustrate the method for the simple comparison of two means in a real data set, provide R code that may be easily implemented in practice, and discuss the extension of the method to other applied problems.     

Allowing for missing genotypes in any members of the nuclear families in transmission disequilibrium test

The Transmission Disequilibrium Test (TDT) detects linkage between a marker and a disease-susceptibility locus in the presence of linkage disequilibrium. The TDT requires data on the genotypes of affected offspring and their parents, which might not always be available. For example, for late onset diseases it might be difficult to find parents still alive, or genotypes of offspring might not be available. Genotyping unaffected siblings, combining different genotype data sets, or assuming a model mechanism for missing parents have all been proposed to deal with missing genotypes in parents but not in offspring. In this paper, we propose a Mendel Inheritance-Transmission Disequilibrium Test (MI-TDT) to impute missing genotypes in any members of a family with two affected offspring. Our method does not require any of the remedies mentioned above but simply utilizes the fundamental property of Mendel Inheritance on the transmission of alleles from parents to offspring. Most importantly, the MI-TDT reassures researchers about the declared significant genes when incomplete data is ignored. We illustrate the MI-TDT by identifying significant genes in type 1 diabetes from the Warren families in the United Kingdom.     

The confused world of sulfate attack on concrete

External sulfate attack is not completely understood. Part I identifies the issues involved, pointing out disagreements, and distinguishes between the mere occurrence of chemical reactions of sulfates with hydrated cement paste and the damage or deterioration of concrete; only the latter are taken to represent sulfate attack. Furthermore, sulfate attack is defined as deleterious action involving sulfate ions; if the reaction is physical, then, it is physical sulfate attack that takes place. The discussion of the two forms of sulfate attack leads to a recommendation for distinct nomenclature. Sulfate attack on concrete structures in service is not widespread, and the amount of laboratory-based research seems to be disproportionately large. The mechanisms of attack by different sulfates—sodium, calcium, and magnesium—are discussed, including the issue of topochemical and through-solution reactions. The specific aspects of the action of magnesium sulfate are discussed, and the differences between laboratory conditions and field exposure are pointed out.Part II discusses the progress of sulfate attack and its manifestations. This is followed by a discussion of making sulfate-resisting concrete. One of the measures is to use Type V cement, and this topic is extensively discussed. Likewise, the influence of w/c on sulfate resistance is considered. The two parameters are not independent of one another. Moreover, the cation in the sulfate salt has a strong bearing on the efficiency of the Type V cement. Recent interpretations of the Bureau of Reclamation tests, both long term and accelerated, are evaluated, and it appears that they need reworking.Part III reviews the standards and guides for the classification of the severity of exposure of structures to sulfates and points out the lack of calibration of the various classes of exposure. A particular problem is the classification of soils because much depends on the extraction ratio of sulfate in the soil: there is a need for a standardized approach. Taking soil samples is discussed, with particular reference to interpreting highly variable contents of sulfates. The consequences of disturbed drainage of the soil adjacent to foundations and of excessive irrigation, coupled with the use of fertilizer, are described. Whether concrete has undergone sulfate attack can be established by determining the change in the compressive strength since the time of placing the concrete. The rejection of this method and the reliance on determining the tensile strength of concrete because of “layered damage” are erroneous. Scanning electron microscopy (SEM) should not be the primary, and certainly not the first, method of determining whether sulfate attack has occurred. Mathematical modeling will be of help in the future but, at present, cannot provide guidance on the sulfate resistance of concrete in structures.Part IV presents conclusions and an overview of the situation, with consideration of future improvements. Appendix A contains the classification of exposure to sulfate given by various codes and guides.     

分子介质中的正子素形成几率与辐射保护效应

从辐射化学的观点出发,引入辐射保护函数(F)的概念,根据云团反应的竞争机理,建立了“理想二元体系”中正子素形成几率和保护函数之间的关系式;并且,根据此关系,对正庚烷——正穴清除剂(二噁烷,三乙胺,吡咯烷)体系的I_3值及对一些阴离子(I~-,Br~-,Cl~-,S~(2-),SCN~-和F~-)水溶液中的I_3值随溶质浓度的变化进行了定量地拟合。发现,在正穴清除剂体系中,吡咯烷与其他两者相比,对正庚烷具有较大的辐射保护效应;而对阴离子水溶液体系,阴离子对水的辐射保护效应从大到小的顺序是:I~-,SCN~-,S~(2-),Br~-,Cl~-,F~-。实际上,F~-对水毫无保护作用。     

Membrane Targeting and GTPase Activity of Rab7 Are Required for Its Ubiquitination by RNF167

Rab7 is a GTPase that controls late endosome and lysosome trafficking. Recent studies have demonstrated that Rab7 is ubiquitinated, a post-translational modification mediated by an enzymatic cascade. To date, only one ubiquitin E3 ligase and one deubiquitinase have been identified in regulating Rab7 ubiquitination. Here, we report that RNF167, a transmembrane endolysosomal ubiquitin ligase, can ubiquitinate Rab7. Using immunoprecipitation and in vitro ubiquitination assays, we demonstrate that Rab7 is a direct substrate of RNF167. Subcellular fractionation indicates that RNF167 activity maintains Rab7′s membrane localization. Epifluorescence microscopy in HeLa cells shows that Rab7-positive vesicles are larger under conditions enabling Rab7 ubiquitination by RNF167. Characterization of its ubiquitination reveals that Rab7 must be in its GTP-bound active form for membrane anchoring and, thus, accessible for RNF167-mediated ubiquitin attachment. Cellular distribution analyses of lysosome marker Lamp1 show that vesicle positioning is independent of Rab7 and RNF167 expression and that Rab7 endosomal localization is not affected by RNF167 knockdown. However, both Rab7 and RNF167 depletion affect each other’s lysosomal localization. Finally, this study demonstrates that the RNF167-mediated ubiquitination of Rab7 GTPase is impaired by variants of Charcot–Marie–Tooth Type 2B disease. This study identified RNF167 as a new ubiquitin ligase for Rab7 while expanding our knowledge of the mechanisms underlying the ubiquitination of Rab7.