New Investigation in Energy Regeneration of Hydraulic Elevators

In the conventional valve-controlled hydraulic elevator, when the cabin moves downwards, the entire potential energy of the cabin is wasted and converted into fluid heat by throttling. Thus, the energy consumption of a traditional hydraulic elevator is much higher than that of the traction elevator. To reduce the energy consumption and power installation requirements, the energy-regenerative hydraulic elevators have been developed since 1997. In this paper, different generations of the design are discussed for energy-regenerative system; in particular, a new generation is focused on in detail. Experimental studies of this new design are carried out to compare the energy consumption of different system designs of hydraulic elevator. Finally, a conclusion is drawn that the new generation of hydraulic elevator can achieve a significant energy-saving performance compared to the traditional elevators.     

疲劳裂纹扩展曲线的正交多项式与三参数指数函数拟合法

回顾了疲劳裂纹扩展a -N曲线的拟合方法。对三参数幂函数拟合方法进行了改进 ,这种方法避免了原方法搜索范围受局限的特点 ;提出了两种新的a-N曲线拟合方法 :正交多项式法和指数函数法 ,并给出了参数估计算法。正交多项式法拟合a -N曲线 ,其相关系数随最高次数的增加而提高 ,指数函数法比改进三参数幂函数拟合精度高 ;指数函数法与正交多项式法相比 ,各个参数具有更为明确的物理意义     

含冲击损伤高强中模碳纤维复合材料层压板压缩剩余强度分析与试验验证

论文以碳纤维复合材料层压板为研究对象,发展了一种模拟复合材料层压板冲击及冲击后压缩的一体化数值分析方法．基于Puck 失效准则和粘聚区模型描述层内损伤与层间损伤,分别采用基于断裂能的双线性型、函数型以及直接折减型等不同损伤折减方法构建了层内损伤预测与演化模型;建立了碳纤维复合材料冲击后压缩数值仿真模型,通过开展不同能量冲击后压缩试验,验证了所发展的数值分析方法的有效性;研究结果表明,采用Puck 失效准则和基于断裂能的双线性损伤演化模型预测冲击后压缩强度时具有较高精度．     

A Nekhoroshev Type Theorem for the Nonlinear Wave Equation in Gevrey Space

In this paper, the authors prove a Nekhoroshev type theorem for the nonlinear wave equation u_(tt)=u_(xx)-mu-f(u),x∈[0, π] in Gevrey space.     

Empirical Bayes Test for the Parameter of the Truncated-Type Distribution Families

The empirical Bayes test (EBT) is proposed for testing H₀ : ₀ H₁ : > ₀ in the truncated-type distribution families. It is found that the EBT proposed is obtained asymptotically optimal and its convergence rate is also obtained.AMS Subject Classification (2000) 62J10, 62G99     

关于山区电信现状与发展策略的探讨

较系统全面地阐述邮电分营和电信重组后山区电信现状及所面临的新形势，并结合山区发展实际，通过多个方面，不同侧面去分析现状和存在问题，对企业改革，生产经营，市场开发及人才问题等方面进行了认真探讨，并提出了较为适合山区电信具体可行的对策和措施。     

Efficient semi-analytical methods for the vibration response of and acoustic radiation from a periodical orthogonally rib-stiffened plate

In order to theoretically predict and analyze the vibration response and acoustic radiation characteristics of a periodical orthogonally rib-stiffened plate,its vibro-acoustic equations of an underwater infinite model are established.The rib-stiffened plate is stimulated by a harmonic plane pressure.By using the Fourier transforms,Poisson's summation formula and space harmonic method,the structural vibration response and acoustic radiation pressure are expressed as functions of displacement harmonic components.Efficient semi-analytical methods are proposed in this work,and then approximate solutions for finite terms of the harmonic components are obtained by employing the truncation technique.Effects of the vibration response,rib spacing and torsional moment of the ribs on the radiation pressure are examined,and the validity of the present methods is also verified.Theoretical results show that the torsional moment of the ribs affects the modal frequencies of the stiffened plate,which should not be neglected in engineering applications with high precision requirement.With attachment of the ribs to the thin plate,its far field radiation pressure can be reduced in the low frequency range by adjusting rib spacing and cross sectional size of the ribs.     

Characterization of methylated and unmethlyated CpG-ODNs by electrospray ionization tandem mass spectrometry

Methylated and unmethylated CpG-ODNs at A-rich, C-rich, G-rich and T-rich conditions were characterized by electrospray ionization tandem mass spectrometry (ESI-MS/MS). The methylted site could be confirmed by comparison of the MS/MS spectra of methylated and unmethylated CpG-ODNs. The fragmentation patterns of the CpG-ODNs were not influenced by the presence of the methyl group but significant effects were observed for nucleobase identities and parent ion charges. The cleavage at guanine was the most facile while that at thymine was the least facile. With the increase of the parent ions charge states, the major dissociation behaviors changed from the middle to the 3' and 5' termini of the sequence.     

Effects of low-molecular-weight organic ligands and phosphate on adsorption of Pseudomonas putida by clay minerals and iron oxide

Adsorption of Pseudomonas putida on kaolinite, montmorillonite and goethite was studied in the presence of organic ligands and phosphate. Citrate, tartrate, oxalate and phosphate showed inhibitive effect on P. putida adsorption by three minerals in a broad range of anion concentrations. The highest efficiencies of the four ligands in blocking the adsorption of P. putida on goethite, kaolinite and montmorillonite were 58–90%, 35–76% and 20–48%, respectively. The ability of organic ligands in prohibiting the binding of P. putida cells to the minerals followed the sequence of citrate > tartrate > oxalate > acetate. The significant suppressive effects on P. putida adsorption were ascribed to the increased negative charges by adsorbed ligands and the competition of ligands with bacterial surface groups for binding sites. The inhibitive effects on P. putida adsorption by organic ligands were also dependent on the steric hindrance of the molecules. Acetate presented promotive effect on P. putida adsorption by kaolinite and goethite at low anion concentrations. The results obtained in this study suggested that the adsorption of bacteria in soils especially in the rhizosphere can significantly be impacted by various organic and inorganic anions.