Wave-based vibration control of large cable net structures

Large cable net structures have been widely applied in aerospace engineering due to the feature of light-weight, high packaging efficiency, and high thermal stability. Structural vibrations induced by a variety of disturbances are inevitable in the space environment, resulting in the requirement of effective vibration control strategies for large cable net structures. Since the large cable net structures have many closely spaced vibrational modes in the range of low frequencies, traditional modal based control may cause modal truncation and spillover problems. In this paper, a wave-based boundary control strategy is adopted and its effectiveness to control the vibration of cable net structures is investigated, by transfer function analysis and numerical methods. It is found that the structural vibration can be absolutely resisted by applying the wave-based boundary controllers onto all the exterior nodes, when disturbances come from the external boundaries of the cable net. Our results in this paper can provide a theoretical basis for the vibration control of large cable net structures.     

Transient vibrations of a tau inclined cable with a riding accelerating mass

The objective of this paper is a theoretical and numerical study of the dynamics of a taut inclined cable with a riding accolerating mass, which is suspended from two points of different elevation. The moving mass is a trolley that is accelerated by a solid fuel rocket down the inclined cable and is aerodynamically brought to a halt. The thrust of the rocket is tangential to the deformed configuration of the cable.Methods of analysis consist of the dynamics of small deformations superimposed on the static catenary state. The problem is nonlinear due to presence of friction and the convective acceleration interaction of the moving mass and the cable. Galerkin's procedure for removal of spatial dependence and numerical integration are used to obtain convergent solutions.Deceased     

Voltammetric Behavior of Arsenic(III) in the Presence of Sodium Diethyl Dithiocarbamate and Its Determination in Water and Highly Saline Samples by Adsorptive Stripping Voltammetry

This paper describes the voltammetric behavior of As(III) at the hanging mercury drop electrode (HMDE) in the presence of sodium diethyl dithiocarbamate (SDDC) and a new voltammetric method for the determination of As(III) at trace levels. The method is based on the adsorptive deposition of a As(III) complex with SDDC at ?0.45 V (vs. Ag/AgCl) on the HMDE in acidic medium of 0.01 mol L^?1 HCl (pH 2.0) and its cathodic stripping during the potential scan (100 mV s^?1). The linear range for the determination of As(III) in the presence of SDDC (4 μmol L^?1) in water samples was between 1 and 10 μg L^?1 for a deposition time of 300 s (r=0.994) and between 10 and 100 μg L^?1 for a deposition time of 60 s (r=0.999). For the determination of As(III) in dialysis concentrate samples, the linear range was between 5 and 25 μg L^?1 for a deposition time of 180 s (r=0.992) and between 10 and 100 μg L^?1 for a deposition time of 60 s (r=0.996). Detection limits of 0.3 and 2.2 μg L^?1 in water and dialysis concentrate samples were calculated for the method using a deposition time of 300 and 180 s, respectively. Recovery values between 93.0 and 110.0% for As(III) added to deionized, mineral, seawater (synthetic and real) and dialysis concentrate samples prove the satisfactory accuracy and applicability of the procedure.     

Determination of Azidothymidine – an Antiproliferative and Virostatic Drug by Square‐Wave Voltammetry

The 3′‐azido‐3′‐deoxythymidine (AZT, Zidovudine) is an antiproliferative and virostatic drug widely used in human immunodeficiency virus type 1 (HIV‐1) infection treatment. With respect to side effects of high doses and a short half‐life of AZT, a fast and simple detection method for this agent could be helpful. The aim of our study was to determine AZT levels in natural samples (urine, serum, whole blood, and cell cultures, such as the HaCaT line of keratinocytes) without their mineralization and/or purification, by means of electrochemical methods using hanging mercury drop electrode (HMDE). On this electrode, AZT undergoes irreversible reduction at the peak potential near E_p?1.1 V (vs. Ag/AgCl/3 M KCl). Reduction AZT signals were measured by cyclic voltammetry (CV), differential pulse voltammetry (DPV), square‐wave voltammetry (SWV), and constant current chronopotentiometric stripping analysis (CPSA). In phosphate buffer (pH 8) the SWV yielded the best AZT signal with the detection limit of 1 nM. The determination of AZT concentration in biological materials is affected by electroactive components, such as proteins and DNA. For monitoring the influence of these compounds, AZT reduction was performed in the presence of 10 μg/mL calf thymus ssDNA and/or 100 μg/mL bovine serum albumin. In these cases, the detection limit increased to 0.25 μM. Also studied was the AZT concentration in keratinocyte cells (HaCaT line) during cell cultivation. It has been shown that the SWV may be considered as a useful tool for the determination of AZT concentration in cell cultures, and for monitoring AZT pharmacokinetics.     

倒数示波计时电位法在合金样品测定中的应用

应用倒数示波计时电位法，在含有吸附络合物的溶液中，采用桂汞电极作为极化电极，测定了Ｃｕ＾２＋、Ｎｉ＾２＋、Ｃｄ＾２＋、Ｐｂ＾２＋等几种金属离子的检测下限，并通过沿（ｄＥ／ｄｔ）－１￣Ｅ曲线上的峰高对合金样品进行定量分析，得到满意结果。实现了示波分析由常量到微量的飞跃。     

Two-stage Off-Gel isoelectric focusing: protein followed by peptide fractionation and application to proteome analysis of human plasma

This paper presents the recently introduced Off-Gel electrophoresis (OGE) technology as a versatile tool to reproducibly fractionate intact proteins and peptides into discrete liquid fractions. The coupling of two stages of OGE, i.e., the separation of intact proteins in a first-stage followed by fractionation of peptides derived from each protein fraction after proteolysis in a second stage, results in an array of 15 x 15 fractions that are directly amenable to additional peptide fractionation like reverse-phase liquid chromatography (RPC). The analysis of all second-stage peptide fractions from only the first-stage protein fraction representing pH 5.0 -5.15 by on-line reverse-phase LC-tandem mass spectrometry resulted in the identification of 53 proteins (337 peptides), of which 10 were on different immunoglobulin (Ig) chains, with an input of only 1.5 mg human blood plasma proteins. Increasing the protein load to approximately 12 mg increased the number of identified proteins in the same protein fraction to 73 proteins (449 peptides), of which 15 were Ig-related. Immunodepletion of six of the most abundant proteins (albumin, transferrin, haptoglobin, IgG, IgA, and alpha-1-antitrypsin) prior to first-stage OGE with an input of 1.5 mg of protein (equivalent to approximately 10 mg nondepleted plasma) resulted in the identification of 81 proteins (660 peptides), of which three were still Ig fragments. The pI-based separation of peptides appears to be nonuniform based on the theoretically determined pI values of identified peptides. This observation specifically accounts for the neutral zone (pI 5-8) and can be accounted for by the physicochemical properties of the peptides given by their amino acid composition. The power of OGE separation of proteins and peptides is discussed with a focus on the use of the knowledge about the pI of proteins and peptides that assist the validation of correct identifications together with the retention time of peptides on RPC.     

Determination of trace arsenic on hanging copper amalgam drop electrode

Hanging copper amalgam drop electrode has been applied for trace determination of arsenic by cathodic stripping analysis. Detection limit for As(III) as low as 0.33 nM (0.02 μg/L) at deposition time (240 s) could be obtained. For seven successive determinations of As(III) at concentration of 5 nM relative standard deviation was 2.5% (n = 7). Interferences from selected metals and surfactant substances were examined. Absence of copper ions in sample solution causes easier optimization and makes method less vulnerable on contamination. The developed method was validated by analysis of certified reference materials (CRMs) and applied to arsenic determinations in natural water samples.     

Elimination of SAS Interferences in Catalytic Adsorptive Stripping Voltammetric Determination of Cr(VI) by Means of Fumed Silica

In the work the procedure of chromium(VI) determination by catalytic adsorptive stripping voltammetry (CAdSV) with application of fumed silica, is presented. Two variants of the method are proposed: in the first fumed silica is put directly to the electrolytic cell containing tested solution, in the second the silica is shaken with the sample and next centrifuged. The effectiveness of many surface‐active substances removal from synthetic solutions as well as natural water samples, is studied. In the experiments the fumed silica (Sigma‐Aldrich) of the specific surface area in the range 200–390 m² g^?1 was used. Two types of the working electrodes were applied, i.e., hanging mercury drop electrode (HMDE) and cyclic renewable mercury film electrode (Hg(Ag)FE). In the silica presence i) the relative standard deviation (RSD) for 0.1 μg L^?1 Cr(VI) is <2% (HMDE) and <5% (Hg(Ag)FE), n=7, ii) the detection limits estimated deposition time 20 s were respectively 14 ng L^?1 (HMDE) and 22 ng L^?1 (Hg(Ag)FE). The accuracy of the method was tested by studying the recovery of Cr(VI) from spiked natural water samples.     

南京长江第三大桥斜拉索的防腐系统研究

根据目前我国拉索型桥梁索结构的防腐体系均遭到不同程度破坏的现状,在对索结构防腐体系破坏原因分析的基础上,结合南京长江第三大桥的特点,研究了拉索的防腐系统。结果表明:选择双峰HDPE护套,及在拉索内填充具有水汽隔绝、阻蚀防腐和润滑抗磨双重作用的防腐填充物,可延长拉索的使用寿命。该研究已成功应用于南京长江第三大桥的斜拉索体系。     

新一代宽带网络接入技术Cable Modem

论述了CableModem的工作原理、传输模式和技术标准 ,以及基于CableModem接入的有线电视宽带网络解决方案 .CableModem通过有线电视CATV的某个传输频道进行调制解调 ,其他空闲的有线电视频道仍可用于传输有线电视信号 ,所以优越于传统Modem :不占用电话线 ,不须拔号及永久连结