Numerical approach to analyze fluid flow in a type C tank for liquefied hydrogen carrier (part 1: Sloshing flow)

The demand for clean energy use has been increasing worldwide, and hydrogen has attracted attention as an alternative energy source. The efficient transport of hydrogen must be established such that hydrogen may be used as an energy source. In this study, we considered the influences of various parameters in the transportation of liquefied hydrogen using type C tanks in shipping vessels. The sloshing and thermal flows were considered in the transportation of liquefied hydrogen, which exists as a cryogenic liquid at ?253 °C. In this study, the sloshing flow was analyzed using a numerical approach. A multiphase sloshing simulation was performed using the volume of fluid method for the observation and analysis of the internal flow. First, a sloshing experiment according to the gas-liquid density ratio performed by other researchers was utilized to verify the simulation technique and investigate the characteristics of liquefied hydrogen. Based on the results of this experiment, a sloshing simulation was then performed for a type C cargo tank for liquefied hydrogen carriers under three different filling level conditions. The sloshing impact pressure inside of the tank was measured via simulation and subjected to statistical analysis. In addition, the influence of sloshing flow on the appendages installed inside of the type C tank (stiffened ring and swash bulkhead) was quantitatively evaluated. In particular, the influence of the sloshing flow inside of the type C tank on the appendages can be utilized as an important indicator at the design stage. Furthermore, if such sloshing impact forces are repeatedly experienced over an extended period of time under cryogenic conditions, the behavior of the tank and appendages must be analyzed in terms of fatigue and brittle failure to ensure the safety of the transportation operation.     

Hot corrosion Type II of FeCr‐based model alloys for boiler and heat exchanger applications

The hot corrosion Type II of the alloys FeCr20, FeCr20Ni10, FeCr20Ni20, and FeCr20Co10 is investigated at 700°C in air + 0.5% SO₂ with deposits consisting of Na₂SO₄ and a eutectic mixture of Na₂SO₄ and MgSO₄ for 24, 100, and 300 h. The alloying elements nickel and cobalt have a positive influence when tests are conducted using a MgSO₄‐Na₂SO₄ deposit. In this case, they reduce the metal loss and increase the time to the propagation stage. In contrast, when the alloys are exposed with a Na₂SO₄ deposit, these alloying elements increase the metal loss and allow for the transition to the propagation stage because they can form molten phases with the Na₂SO₄. During the incubation stage an oxide scale forms on the FeCr20 alloy, which is thicker than the one formed during exposure without a deposit, and iron oxides are observed, which precipitate in the deposit. The propagation stage occurs by a dissolution and precipitation mechanism forming localized pitting attack. Iron is the main species that dissolves and precipitates, while chromium remains mainly as an oxide beneath the initial surface. The additional elements are found in the pit and in the salt deposit.     

Type II fuzzy set-based data analytics to explore amino acid associations in protein sequences of Swine Influenza Virus

The veracity present in molecular data available in biological databases possesses new challenges for data analytics. The analysis of molecular data of various diseases can provide vital information for developing better understanding of the molecular mechanism of a disease. In this paper, an attempt has been made to propose a model that addresses the issue of veracity in data analytics for amino acid association patterns in protein sequences of Swine Influenza Virus. The veracity is caused by intra-sequential and inter-sequential biases present in the sequences due to varying degrees of relationships among amino acids. A complete dataset of 63,682 protein sequences is downloaded from NCBI and is refined. The refined dataset consists of 26,594 sequences which are employed in the present study. The type I fuzzy set is employed to explore amino acid association patterns in the dataset. The type I fuzzy support is refined to partially remove the inter-sequential biases causing veracity in data. The remaining inter-sequential biases present in refined fuzzy support are evaluated and eliminated using type II fuzzy set. Hence, it is concluded that a combination of type II fuzzy & refined fuzzy approach is the optimal approach for extracting a better picture of amino acid association patterns in the molecular dataset.     

变频调速系统中电动机和变频器选择及问题分析

本文分析了选用标准笼形电动机的容量计算方法、问题分析和选用变频器的型式、容量、注意事项。     

SQL的现状及其研究与发展

一、SQL简介 如果说七十年代关系数据库还处于研制实验阶段,那么到了八十年代大量关系数据库商用产品的面市几乎占据了整个数据库市场,其中的原因在于它们使用了统一的语言界面,那就是,SQL成为了关系数据库的通用语言。 1974年．IBM公司San Jose研究实验室的D．D．Chamberlin在开发SEQUEL-XRM原型时提出了SE-QUEL(Structured English Query Language),1976年又修改成为SEQUEL／2．也就是目前的SQL(StructuredQuer Language)。SEQUEL／2主要成形于IBM的Sys-tem R原型中[2],并在原有基础上大加扩展,其后逐渐完善并最终成为一种完备的结构化数据库查询语言。     

Type inference in stack based languages

We consider a language of operations which pass parameters by means of a stack. An algebra over the set of type signatures is introduced, which allows the type signature of a program to be obtained from the type signatures of its constituent operations.Although the theories apply in principle to any stack based language, they have been evolved with particular regard to the proposed ANSI Standard Forth language, which is currently implemented in a type free manner. We hope this work will stimulate an interest in Forth amongst those applying algebraic techniques in software engineering, and we hope to lay the theoretical foundations for implementing practical type checkers to support Forth.     

Evaluation of Monkman-Grant parameters for type 316LN and modified 9Cr-Mo stainless steels

The Monkman-Grant (M-G) and its modified parameters were evaluated for type 316LN and modified 9Cr-Mo stainless steels prepared with minor element variations. Several sets of creep data for the two alloy systems were obtained by constant-load creep tests in 550-650°C temperature range. The M-G parameters,m, m’,C, andC’ were proposed and discussed for the two alloy systems. Them value of the M-G relation was 0.90 in type 316LN steel and 0.84 in modified 9Cr-Mo steel. Them’, value of the modified relation was 0.94 in type 316LN steel and 0.89 in 9Cr-Mo steel. Although creep fracture modes and creep properties between type 316LN and modified 9Cr-Mo steels showed a basic difference, the M-G and its modified relations demonstrated linearity quite well. Them’ of modified relation almost overlapped regardless of the creep testing conditions and chemical variations in the two alloy systems, and the parameterm’ was closer to unity than that of the M-G relation.     

Damage mechanism in weldment of 2.25Cr-1Mo steel under creep-fatigue loading

The purpose of this study is to clarify damage process of “Type IV cracking” in weldment of a 2.25Cr-1Mo steel and to propose a micro damage prediction method. From continuous observation under a creep-fatigue test, it was found that spherical shape voids initiated and grew on grain boundaries in fine grain region and these voids grow continuously by changing their shape to crack-like. Both spherical and crack-like void growth rate equations were derived from the proposed void growth model. It was indicated that measured void growth rate under the creep-fatigue loading was well predicted by the growth rate equations.     

提高检测数据准确性 促进选钼生产稳定高效

本文从6个方面对选钼2个作业段的取样方式进行了校验,通过对检测数据的比对分析,找出了选钼2个作业段数据存在矛盾的原因,并针对原因采取了有效的措施,保证了检测数据的准确性,促进了选钼生产的稳定高效。     

Integrated development of CFRP structures for a topless high performance vehicle

When modern saloon cars are re-engineered as convertibles (or roadsters) it is typical for them to lose 50% or more of the body’s torsional rigidity. Consequently the vehicles rarely handle quite as crisply, nor do they ride as well as the coupes from which they derived. This paper highlights the fundamental contributions of advanced composites in achieving the desired value of handling of the Murcièlago Roadster without penalizing the overall weight of the vehicle. To compensate for the absence of the roof structure, the vehicle was strongly redesigned by introducing new structural members and reinforcing existing critical components. A new all-carbon/epoxy composite sub-frame, which spans the entire engine bay, is comprised of elliptical tubular members, and it is the first of its kind in a production vehicle. Engineering of the sub-frame, from preliminary design to manufacturing decisions, is the focus of this paper, and is achieved through a Building Block approach that sets the program within the Integrated Product Development (IPD) strategy that the Advanced Composites Division of Automobili Lamborghini S.p.A. employs for its technology demonstrators. The strategy consists in a concurrent analytical and experimental development of the product, from the initial conceptual design and coupon testing, through the stages of element and subcomponent engineering, to final component manufacturing.