Modeling and Optimization of Nanofluid Flow in Flat Tubes Using a Combination of CFD and Response Surface Methodology

In this paper, modeling and optimization of Al₂O₃–water nanofluid flow in horizontal flat tubes is performed using a combination of computational fluid dynamics (CFD) and response surface methodology (RSM). At first, nanofluid flow is solved numerically in various flat tubes using CFD techniques and the heat transfer coefficient () and pressure drop () in tubes are calculated. The numerical simulations are performed using two phase mixture model by FORTRAN programming language. The flow regime and the wall boundary conditions are assumed to be laminar and constant heat flux respectively. In the second step, numerical data of the previous step will be used for a parametric study, modeling and optimization of nanofluid flow in flat tubes using the RSM technique.It is shown that the results include important design information on nanofluid parameters in flat tubes. The important design information about the relationship between design variables and responses will not be achieved without the simultaneous use of CFD and optimization approaches.     

城市避震疏散交通系统及评价方法体系研究

城市避震疏散是城市防灾系统的重要组成部分,是抗震救灾的关键,对地震发生期间避震疏散交通类型、特点及各相关系统展开研究,分析整个系统的构成及特点,探讨疏散交通与疏散空间、疏散通道以及相互之间的关系,在总结前人在避震疏散规划理论和方法的基础上进行梳理和补充,尝试性地建立起一套相对较为完整的评价方法体系,包括了对避震疏散空间的服务覆盖、服务重复和服务质量等,避震疏散通道的通达性和可靠性,以及避震疏散空间与疏散通道相互配合的吻合情况和服务的薄弱度等方面的综合评价。希望通过本研究,为城市进行更加科学合理的避震疏散规划和震前预防、震中避难和震后救援等各项部署提供帮助。     

Stepwise‐refinement for performance: a methodology for many‐core programming

Many‐core hardware is targeted specifically at obtaining high performance, but reaching high performance is often challenging because hardware‐specific details have to be taken into account. Although there are many programming systems that try to alleviate many‐core programming, some providing a high‐level language, others providing a low‐level language for control, none of these systems have a clear and systematic methodology as a foundation. In this article, we propose stepwise‐refinement for performance: a novel, clear, and structured methodology for obtaining high performance on many‐cores. We present a system that supports this methodology, offers multiple levels of abstraction to provide programmers a trade‐off between high‐level and low‐level programming, and provides programmers detailed performance feedback. We evaluate our methodology with several widely varying compute kernels on two different many‐core architectures: a Graphical Processing Unit (GPU) and the Xeon Phi. We show that our methodology gives insight in the performance, and that in almost all cases, we gain a substantial performance improvement using our methodology. Copyright © 2015 John Wiley & Sons, Ltd.     

A construction project cash flow model—an idiographic approach

The paper introduces and supports the contention that an idiographic methodology is appropriate to the post- hoc study and interpretation of individual construction project cash flows. A cash flow model based on the logit transformation is proposed to be consistent with this methodology. The model is based on historical data, and yields two parameters to describe each individual project. The model is tested using two samples totalling 72 projects. Goodness of fit for the model, using a measure of standard deviation from 1.0% to 4.6%, with a median of 2.5%, is found for individual projects.

The experimental hypothesis (that there is substantial variation between projects) is supported by the graphical and statistical evidence of deviation, which is argued to be the result of the individual ontology of each project - systematic error - rather than random error from an ideal. The paper concludes that forecasts of individual cash flows are invalid when derived from analysis of grouped data.     

Public reaction to wind development in California

Substantial controversy has been produced from the location of over 4000 wind turbines in San Gorgonio Pass, California. The principal point of controversy is the conflicting land use which results from developing wind power in a populated area. A public opinion survey was conducted which demonstrated that the vocal opposition to the wind turbines so commonly expressed is not borne out in fact. While there is indeed some opposition to the development of wind power at this site, particularly in terms of aesthetic degradation, the majority of respondents favoured the development. This level of approval will be of interest to those developing large wind projects elsewhere.     

Optimisation of process parameters for electroless nickel plating on SS316L for refrigeration systems

Nowadays, refrigeration systems are important for industrial and domestic applications. The coefficient of performance of a vapour compression refrigeration system can be improved if a reduction in the work of compression can be achieved by a suitable technique for a specified heat removal rate. The present study investigates the effect of material coating of electroless nickel (EN) plating. The friction and wear experiments were performed using a four-ball machine tribo tester. Controlling the EN plating parameters plays an important role in the quality of coating. It depends on the wear scar rate of the coated material. So it is necessary to optimise the process parameters of EN plating. The experimental studies have been conducted under varying pressure, load and time on quality characteristics. In this paper, optimisation of process parameters using response surface methodology technique for EN plating was discussed.     

Optimization of supercritical CO2 extraction of dried Helichrysum italicum flowers by response surface methodology: GC-MS profiles of the extracts and essential oil

Supercritical (SC) CO₂ extraction of dried Immortelle flowers was performed at different process parameters. The optimal extraction conditions related to the yield were determined by response surface methodology (yield 4.09% at 20 MPa and 52°C). The extracts were analyzed by GC-MS and tremetone derivatives dominated: bitalin A, 12-acetoxytremetone, gnaphaliol, 1-[2-(2-methyl-2,3-dihydroxypropyl)-2,3-dihydro-1-benzofuran-5-yl]ethanone, isobutyl bitalin A, and 1-[2-(acetylprop-1-en-2-yl)-3-hydroxy-2,3-dihydro-1-benzofuran-5-yl]ethanone. Striking differences were found among the essential oil and SC-CO₂ extracts composition. The major oil compounds were γ-curcumene, α-pinene, β-selinene, α-selinene, and limonene. Mono- and sesquiterpene were found among minor constituents of the extracts. Neryl acetate was present in the extracts and essential oil.     

Bioaccumulation of As(III)/As(V) ions by living cells of Corynebacterium glutamicum MTCC 2745

Significant factors on simultaneous growth and bioaccumulation of arsenic ions by living cells of bacteria, Corynebacterium glutamicum MTCC 2745, were explored in growth media under experimental conditions like pH and concentrations of arsenic ions. Combined effects of the initial concentrations of peptone and arsenic (either As(III) or As(V)) ions on the specific growth rate and arsenic bioaccumulation competence of the bacteria were studied and optimized using the Response Surface Methodology. Optimum combination predicted via RSM demonstrated that the bacteria were capable of bioaccumulating As(III) and As(V) in the growth medium containing 1000 mg/L arsenic and 9 g/L peptone up to 78.4% and 77.6%, respectively.     

薄铺层层合复合材料研究进展

简要介绍了碳纤维薄层预浸料及其制备的层合复合材料,主要阐述碳纤维薄层预浸料的制备方法和薄铺层复合材料的力学性能特点。对国内外关于薄铺层复合材料与常规铺层复合材料的静态、韧性和疲劳等力学性能的研究进展进行了分析和总结,归纳了铺层厚度的减薄对层合复合材料力学性能的影响规律。最后对薄铺层复合材料的研究趋势和应用前景进行了展望。