Near surface flaw detection by ultrasonic critical angle imaging

Acoustic critical angle measurements usually involve broad beam or global isonification of a water-solid interface. In order to obtain local interface data, it is convenient to use a focused acoustic source with lens axis at incident angle and point-receiver at specular reflection angle . By scanning this combination at various critical angles (=_crit), interface waves are generated locally near the lens focus. These waves penetrate the solid to a depth of approximately one shear wavelength _T and are modulated by discontinuities such as flaws, inclusions, and debonds that may be present there. A radiated longitudinal wave in water accompanies these modulated interface waves and carries information on subsurface flaws to the point-detector along the direction of a specularly reflected wave. By scanning the focus-receiver combination along the interface, the receiver output may be used to form images of local subsurface detail. We show that in anisotropic materials, such as crystals, there are generally two different _crit where a radiating interface wave provides subsurface information. We also discuss special problems associated with the use of a focused acoustic source including nonlinear effects (generation of harmonics) in the water.     

Plastic Injection Molding of High-Aspect Ratio Micro-Rods

Technological advancements have led to an increase in demand for fabrication of small and cheap miniature components or parts, especially in the medical and electronic fields. In this research work, micro-rods of varying lengths and diameters were molded using a specially designed tabletop injection molding machine. The main purpose was to investigate whether complete filling of the microcavities was possible and whether small cavity openings will restrict melt flow into the cavities.

Process parameters, such as injection pressure, mold temperature and melt temperature were varied. The micro-rods obtained were analyzed with Scanning Electron Micrographs (SEM). The results showed that injection pressure was the most important parameter for microinjection molding. The use of a vacuum system also yielded better results.     

基于人体能量的微传感器节点能量利用方法

计算技术、通信技术和微机电技术的快速发展为智能传感器网络的广泛使用提供了坚实的技术基础。能量供给技术是智能传感器网络的关键技术，因为只有长效、低廉的能量才能保证微传感器节点的正常运行和发挥其独特的作用。传统的电池供能技术已满足不了大规模传感器网络微节点对能量的需求。因此，需要研究新的节点能量供给方法和技术以满足微节点的特殊需求。本文讨论了基于微机电系统（MEMS）技术收集人体能量为微节点供能的方法，并给出了相应的计算模型，这些模型对传感器微节点的能源设计和智能传感器网络的广泛应用具有重要意义。     

微地形对输电线路影响的探讨

利用国内外输电线路通过微地形地段风速研究的方法,通过微地形地段调查及确定,进行微地形地段气候成因分析,研究微地型对风速的影响,提出在福建沿海输电线路工程中应用的关键。     

汽车用高强度大梁板的开发

介绍了具有高强度性能要求的汽车大粱板的成分设计思路及试制检验结果，提出了试制过程中存在的问题，试制钢种满足汽车生产厂新的技术要求，为该类钢在我厂批量生产进行了积极的探索。     

Construction of Constitutive Relationships of the Deformation Theory for Simple in Noll's Sense Hardening Materials with Elastoplastic Behavior

Based on the theory of simple hardening materials with elastoplastic behavior, the general constitutive relationships of the deformation theory of plasticity are mathematically strictly constructed for arbitrary continuous, piece-wise continuously differentiable deformation trajectories, any strains and symmetry types of the material properties. Two conditions under which this is possible are considered. The approaches to a strict specialization of general constitutive relationships of the deformation theory of plasticity have been developed by imposing restrictions on the material strains, deformation processes and properties. In this case, the restrictions on the properties of materials formalize the data obtained in the experimental investigations. A series of both new and known constitutive relationships have been constructed that are arranged into a hierarchy according to the level of complexity of the response to deformation. The area of applicability of the derived physical equations has been defined. Special attention has been given to the modeling of finite and infinitesimal strains of isotropic materials. __________ Translated from Problemy Prochnosti, No. 6, pp. 35 – 49, November – December, 2005.     

Micromechanical constitutive modelling of granular media: Evolution and loss of contact in particle clusters

Micromechanical constitutive equations are developed which allow for the broad range of interparticle interactions observed in a real deforming granular assembly: microslip contact, gross slip contact, loss of contact and an evolution in these modes of contact as the deformation proceeds. This was accomplished through a synergetic use of contact laws, which account for interparticle resistance to both sliding and rolling, together withstrain-dependent anisotropies in contacts and the normal contact force. By applying the constitutive model to the bi-axial test it is demonstrated that the model can correctly predict the evolution of various anisotropies as well as the formation of a distinct shear band. Moreover, the predicted shear-band properties (e.g. thickness, prolonged localisation, void ratio) are an even better fit with experimental observations than were previously found by use of previously developed micromechanical models.     

The Metal-Dielectric Resonator Method of Measuring the Parameters of Radio Materials

The use of symmetrical H- and E-modes and asymmetrical E-modes in a longitudinally anisotropic dielectric cylinder with metal mirrors at the ends to measure its permittivity and dielectric loss tangent is considered. It is shown that the method has wider possibilities compared with the IEC-61338 recommendations. The results of a measurement of the dielectric parameters of a number of materials in the 2–78 GHz frequency band, including the permittivity tensor of sapphire, are presented. __________ Translated from Izmeritel'naya Tekhnika, No. 9, pp. 65–70, September, 2005.     

降低实时微内核系统中内核封锁粒度的方法

内核封锁较度在很大程度上决定了实时系统的性能。该文说明了实时微内核操作系统在内核封锁粒度方面存在的问题，分析了两种已有处理方法的弊端，提出了一种改进的方法和它的变体。     

基于模糊控制的钢轨双频淬火微机系统

对典型Fuzzy控制器的优缺点进行深入分析的基础上，提出了对多变量非线性系统使用Fuzzy-PI的控制策略，用于提高钢轨淬火生产线的温度控制精度，提高产品质量。现场运行表明，系统稳定性好，抗干扰能力强，超调量小，过渡时间短，实现了工况的自动监测、控制，其精度完全达到预期要求。