A novel phase noise reduction technique in oscillators usingdefected ground structure

A new technique to reduce the phase noise in microwave oscillators is developed using the resonant characteristic of the defected ground structure (DGS). Two kinds of oscillators have been designed and measured for the examination of the reduction of phase noise by the DGS. The first adopts the DGS section under the microstrip line at the gate circuit, while the second has only the conventional microstrip line. Measurement shows reduced phase noise by 10-15 dB in the oscillator with the DGS compared to the conventional one     

A precision on-line model for the prediction of roll force and roll power in hot-strip rolling

Investigated via a series of finite-element (FE) process simulations is the effect of diverse process variables on some selected nondimensional parameters characterizing the thermomechanical behavior of the strip in hot-strip rolling. Then, on the basis of these parameters an on-line model is derived for the precise prediction of roll force and roll power. The prediction accuracy of the proposed model is examined through comparison with predictions from a FE process model and also with measurements.     

溶胶-凝胶法制备疏水型SiO-2气凝胶

以正硅酸乙酯 (TEOS)为硅源 ,用三甲基氯硅烷 (TMCS)为疏水试剂 ,通过溶胶 凝胶法在室温下制备出疏水型SiO2 气凝胶。用傅立叶变温红外 (FT IR)、扫描电镜 (SEM)、透射电镜 (TEM)和吸水性能对疏水型SiO2气凝胶的结构和性能进行了研究     

Thermomechanical Models of Irreversible Finite Deformation of Anisotropic Solids

The proposed models for irreversible finite deformation of initially anisotropic solids are based on the hypothesis of the parameters of state, for which the authors have chosen a universal parameter (temperature) and a strain component, which is analogous to volume strains in an isotropic body and represents thermal strains of an unconstrained (stress-free) anisotropic solid. The application of this hypothesis allows the strain tensor to be resolved into a reversible and irreversible components. For irreversible processes of finite deformation of hardenable materials, the authors have proposed a deformation-type model, which makes it possible to describe a change in the type of anisotropy of initially anisotropic materials in the course of deformation. For the flow-theory-type model, the limiting state function, as given in the space of irreversible strains, allows for the experimentally observed plastic flow of anisotropic crystals under the action of hydrostatic pressure only.     

Isothermal Gas Forming of Mg Alloy AZ31 Sheet

There have been reports on sheet forming of Mg alloy in industry via the punch and die method;this paper is probably the first formal one for studying the sheet formability of AZ31 employing pressurized gas to press the sheet into a female die cavity at various elevated temperatures.The results indicate it is feasible to form a rectangular box via pressurized gas from extruded sheets of 0.5 and 1.7 mm thick.The formed box has 1:2 depth over width ratio,which should be large enough when dealing with realistic industrial sheet forming parts.Presently,forming a sheet of 0.5 mm thick is considered a technical challenge by industry,and it is conquered as demonstrated in this paper.Gas forming technique applied to Mg alloy is unprecedented and shows potential for industrial utilization.     

低剂量X射线照射诱导HeLa细胞存活的

采用集落形成法观察了低剂量X射线照射HeLa细胞的存活率，结果表明，小于0．5Gy的X射线照射细胞的存活率高于对照，得到了HeLa细胞存活的“兴奋效应”，而且在0．25Gy附近这种效应更为明显；低剂量D1（0．05，0．75Gy)的预照射降低了随后攻击量D2对细胞的损伤程度，反映出低剂量照射可诱发细胞存活的“适应性反应”。     

Simple algorithms for searching a polygon with flashlights

The k-searcher is a mobile guard whose visibility is limited to k rays emanating from her position, where the direction of each ray can be changed continuously with bounded angular rotation speed. Given a polygonal region P, is it possible for the k-searcher to eventually see a mobile intruder that is arbitrarily faster than the searcher within P? We present O(n²)-time algorithms for constructing a search schedule of the 1-searcher and the 2-searcher, respectively. Our framework for the 1-searcher can be viewed as a modification of that of LaValle et al. [Proc. 16th ACM Symp. on Computational Geometry, 2000, pp. 260-269] and is naturally extended for the 2-searcher.