广义分布参数系统的状态反馈稳定性问题(1)

关于系统的状态反馈稳定性问题的研究一直是现代控制理论研究的重要问题之一.广义分布参数系统是比分布参数系统更广的一类系统,在研究复合材料热导体中的温度分布等问题时会出现这样的系统.本文讨论了H ilbert空间中一阶广义分布参数系统的状态反馈稳定性问题.应用泛函分析及线性算子半群理论的方法给出了使闭环广义分布参数系统渐进稳定的充要条件,充分条件及状态反馈的构造性表达式.这对研究广义分布参数系统的状态反馈稳定性问题具有重要的理论价值.     

防污染的自消应力高纯度气体低温换热器的设计

该设计解决了低温工程与低温技术等领域所使用的高纯度气体介质换热的要求,具有显著的经济效益和社会效益。其换热器是由四个管壳式热交换器串联组合而成,壳体呈窄矩形,换热管采用U形换热管,四个管壳式热交换器呈方阵置放在低温换热器筒体内。低温换热器采用的材料是0Cr18N i9/304,该种材料的透气性小、耐磨损、抗腐蚀能力强和性能稳定,防止了气体被污染。另外在低温下,考虑了材料的热胀冷缩所产生的应力,使应力能够自行消除,提高了它的密封性能,最终使低温换热器密封性能好,防止了气体被污染,保证了气体的高纯度。     

激光干涉法测引力常量

在扭摆法测量引力常量的基础上,提出利用激光干涉法测扭转偏角,并采用磁感应力来消减周围环境的噪声干扰,能使引力常量G的测量精度有很大提高.     

Interaction of Short Laser Pulses in Wavelength Range from Infrared to X‐ray with Metals,Semiconductors, and Dielectrics

Laser‐matter interaction is defined by an electronic band structure of condensed matter and frequency ω_L of electromagnetic radiation. In the range of moderate fluences, the energy absorbed by electrons from radiation finally thermalizes in the ion thermal energy. The thermalization processes are different for optical as compared with X‐ray quanta and for metals relative to semiconductors and dielectrics, since the light absorption and electron‐electron, electron‐ion dynamics are sensitive to the electron population in a conduction band and the width of a forbidden gap. Although the thermalization processes are different, the final state is simply a heated matter. Laser heating creates powerful stresses in a target if duration of a laser pulse τ_L is short in acoustic time scale. Nucleation and material removal take place under such stresses. Such way of removal is called here the spallative ablation. Thus the spallative ablation is an ablation mechanism universally important for qualitatively different materials and quanta (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

基于代数滑移模型的光催化反应器内催化剂颗粒分布特性研究

针对光催化制氢反应器内液固两相流的特点,运用代数滑移模型,对反应器内的催化剂颗粒-水两相流动进行了数值模拟。采用分块的结构化网格,并运用多重网格方法进行求解。通过与前人实验中压力梯度结果的比较,对模型进行了验证,并最终得到了反应器内催化剂颗粒的典型分布及相应的类型图。     

Progress in DNA Aptamers as Recognition Components for Protein Functional Regulation

Proteins play a central role in all domains of life, and precise regulation of their activity is essential for understanding the related biological processes and therapeutic functions. Nucleic acid aptamers, the molecular recognition components derived from systematic evolution of ligands by exponential enrichment(SELEX), can specifically identify proteins with antibody-like recognition characteristics and help to regulate their activity. This minireview covers the SELEX-based selection of protein-binding aptamers, membrane protein analytical techniques based on aptamer-mediated target recognition, aptamer-mediated functional regulation of proteins, including membrane receptors and non-membrane proteins(thrombin as a model), as well as the potential challenges and prospects regarding aptamer-mediated protein manipulation, aiming to supply some useful information for researchers in this field.     

Influence of pressure on the relative population of the two lowest vibrational levels of the C <Superscript>3</Superscript> Π<Subscript>u</Subscript> state of nitrogen for electron beam excitation

Continuous and pulsed 12 keV electron beams were used to excite nitrogen within a gas cell at pressures ranging from 10 to 1400 hPa. The pressure dependence of the ratio of photon fluxes for emission from vibrational levels v'=0 and 1 of the C ³Π _u state has been studied. The results confirm the presence of a collisional excitation mechanism populating v'=0, 1 in addition to electron impact excitation. Rate constants of (1.27 ±0.04)×10^-11 cm³s^-1 [ v'=0] and (2.68 ±0.08)×10^-11 cm³s^-1 [ v'=1] were measured for C ³Π _u quenching by ground state nitrogen. For electron beam conditions relative excitation efficiencies of 1:0.59:0.22 for vibrational levels 0, 1 and 2 were calculated. The recorded flux ratios are compared with the predictions given by a vibrational relaxation model.     

Multiplicity distribution of final-state particles and different contributions of related Sources in nucleus-nucleus collisions at high energies

The final state particle multiplicity distributions in high-energy nucleus-nucleus collisions are described by two different sub-distributious contributed by a single nucleon.The Monte Carlo calculated results from the two sub-distributions and the participant-spectator model are compared and found to be in agreement with the experimental data of Au-Au collisions ats=130 AGeV and Pb-Pb collisions at 158 AGeV.     

Quincunx fundamental refinable functions and quincunx biorthogonal wavelets

We analyze the approximation and smoothness properties of quincunx fundamental refinable functions. In particular, we provide a general way for the construction of quincunx interpolatory refinement masks associated with the quincunx lattice in . Their corresponding quincunx fundamental refinable functions attain the optimal approximation order and smoothness order. In addition, these examples are minimally supported with symmetry. For two special families of such quincunx interpolatory masks, we prove that their symbols are nonnegative. Finally, a general way of constructing quincunx biorthogonal wavelets is presented. Several examples of quincunx interpolatory masks and quincunx biorthogonal wavelets are explicitly computed.

     

Initiation of Light Pulses by a Coaxial H‐Compressed Discharge

An optimum configuration of the discharge channel of a coaxial Hcompressed discharge is determined to exclude the screening influence of an envelope on discharge radiation in the UV region of a spectrum. It is shown that the use of an Hcompressed discharge of coaxial shape makes it possible to increase the radiation yield in the UV spectrum as compared to a plane shape at the same parameters of electric power supply.