Abstract Implementation of Algebraic Specifications in a Temporal Logic Language

A formal technique for incorporating two specification paradigms is presented,in which an algebraic specification is implemented by a set of abstract procedures specified in pre and post-condition style.The link between the two level specifications is provided via a translation from terms of algebraic specifications into temporal logic formulae representing abstract programs.In terms of translation,a criterion for an abstract implementation satisfying its specification is given,which allows one to check the consistency between the two levels of specifications.The abstract implementations can be refined into executable code by refining each abstract procedure in it.It is proved that the satisfication relation between a specification and its implementations is preserved by such refinement steps.     

Review on the effect of heat exchanger tubes on flow behavior and heat/mass transfer of the bubble/slurry reactors

Bubble/Slurry bubble column reactors(BCR/SBCR) are intensively used as multiphase reactors for a wide range of application in the chemical, biochemical and petrochemical industries. Most of these applications involve complicate gas–liquid/gas–liquid–solid flow behavior and exothermic process, thus it is necessary to equip the BCR/SBCR with heat exchanger tubes to remove the heat and govern the performance of the reactor. Amounts of experimental and numerical studies have been carried out to describe the phenomena taking place in BCR/SBCRs with heat exchanger tubes. Unfortunately, little effort has been put on reviewing the experiments and simulations for examining the effect of internals on the performance and hydrodynamics of BCR/SBCR. The objective of this work is to give a state-of-the-art review of the literature on the effects of heat exchanger tubes with different types and configurations on flow behavior and heat/mass transfer, then provide adequate information and scientific basis for the design and the development of heat exchanger tubes in BCR/SBCR, ultimately provide reasonable suggestions for better comprehend the performance of different heat exchanger tubes on hydrodynamics.     

Performance Comparison of Long-Wave Infrared Imaging Spectrometer Between Dyson Form and Offner Form

In view of the difficulties in traditional long-wave infrared imaging spectrometer which is hard to realize a high signal-to-noise ratio and miniaturization as well under the weak remote sensing signal,Offner convex grating spectrometer and Dyson concave grating spectrometer,both having concentric structure,are designed and analyzed in the band of 8-12 μm. The diffraction angle expressions of the two spectrometers are obtained and the diffraction characteristics are acquired. Both of the spectrometers are designed in Zemax environment under different F-numbers and different grating constants with the same slit,spatial resolution,spectral resolution and detector. The results show that Dyson grating spectrometer possesses the advantages of higher throughput and smaller volume, and Offner grating spectrometer possesses the advantage of more accessible material and the absence of chromatic aberration. The differences between Dyson form and Offner form show that the former is a better choice in the long-wave infrared imaging spectrometer.     

板料成形仿真软件--DYNAFORM

一、冲压模拟仿真技术 背景 从20世纪中期,人们就已经开始利用有限元算法对钣金成形进行模拟仿真研究.1970年至1980年,钣金成形模拟分析技术已被广泛用于分析轴对称、平面变形等问题.近几年,由于可以在计算机中预先对可能出现的问题求解、分析并进行工艺优化,而不是通过实际试模来解决可能出现的问题,为企业带来了巨大的经济效益.因此,冲压模拟仿真技术被企业广泛采用,该技术的不断发展以及高速度、低价格的计算机的出现,使金属成形的加工费用更加低廉.     

PESOI： Process Embedded Service-Oriented Architecture

1 Introduction Service-Oriented Architecture (SOA) has received significant attention recently as major computer and software companies such as HP, IBM, Intel, Microsoft, and SAP, have all embraced SOA, as well as government agencies such as DoD (US depar…     

板料激光加热三维瞬态温度场的数值模拟

考虑了对流、辐射以及材料的热物性与温度的相关性，建立了板料激光加热时三维瞬态温度场的数学模型，用小步距间歇跳跃式移动光源来代替激光束的连续扫描，对该温度场进行了非线性有限元数值模拟，并将模拟结果与其它模型的结果进行了比较，为进一步定量分析板料的热变形提供了依据。     

Ductility Anisotropy Induced by Ferrite in Direct Laser Deposited 17-4 PH Steel: Combined Microstructure and Dislocation Density Simulation

The anisotropic ductility of a direct laser deposited 17-4 PH cubic part was investigated. Anisotropic elongations in the specimens from varied surfaces of the part were obtained: ～ 6.2%, ～ 1.5%, and ～ 4.5% in XY, YZ, and XZ samples, respectively. Furthermore, various orientations of ferrite were found in different specimens, taking the loading direction as reference. A finite element analysis depending on actual microstructures and dislocation density revealed that the orientation of ferrite caused the ductility anisotropy. The orientation of ferrite affected its plastic deformability and the deformation compatibility between phases during the uniaxial loading. The ferrite parallel to the tensile direction in the YZ sample had the worst deformability and induced severe strain localization and stress triaxiality, which resulted in inferior ductility. The ferrite perpendicular to the tensile direction showed the best deformability, whereas strain localization remained intense in the XZ sample owing to the unmatched deformability of martensite. The inclined ferrite in the XY sample exhibited moderate deformability and was found to enhance the plastic fl ow of martensite, leading to the best deformation compatibility and ductility.     

Surface-tailoring chlorine resistant materials and strategies for polyamide thin film composite reverse osmosis membranes

Polyamide thin film composite membranes have dominated current reverse osmosis market on account of their excellent separation performances compared to the integrally skinned counterparts. Despite their very promising separation performance, chlorine-induced degradation resulted from the susceptibility of polyamide toward chlorine attack has been regarded as the Achilles’s heel of polyamide thin film composite. The free chlorine species present during chlorine treatment can impair membrane performance through chlorination and depolymerization of the polyamide selective layer. From material point of view, a chemically stable membrane is crucial for the sustainable application of membrane separation process as it warrants a longer membrane lifespan and reduces the cost involved in membrane replacement. Various strategies, particularly those involved membrane material optimization and surface modifications, have been established to address this issue. This review discusses membrane degradation by free chlorine attack and its correlation with the surface chemistry of polyamide. The advancement in the development of chlorine resistant polyamide thin film composite membranes is reviewed based on the state-of-the-art surface modifications and tailoring approaches which include the in situ and post-fabrication membrane modifications using a broad range of functional materials. The challenges and future directions in this field are also highlighted.     

Wire Arc Additive Manufactured CuMn13Al7 High-Manganese Aluminium Bronze

In this work, high-manganese aluminium bronze CuMn₁₃Al₇ samples were prepared by arc additive manufacturing technology. The phase composition, microstructure, and crystal structure of the high-manganese aluminium bronze Cu Mn13Al7 arc additive manufactured samples were analysed using direct-reading spectrometer, metallographic microscope, scanning electron microscope, and transmission electron microscope. The micro-hardness tester, tensile tester, impact tester, and electro...