千瓦级微波等离子体质谱仪研究水体中锰元素

为了使微波等离子体电离源更好地用于分析水溶液中金属元素,本研究基于改进型千瓦级微波等离子体（KMP）电离源耦合线性离子阱质谱仪（LTQ MS）,在新型进样系统（Nafion H2SO4）下,研究水体中锰元素的质谱行为。锰元素的千瓦级微波等离子体质谱（KMP MS）特征谱图不同于传统的电感耦合等离子体（ICP MS）获得的特征信号,这可能有助于金属元素分析。使用KMP LTQ MS法分析水体中锰的络合物阴离子,证实锰的络合物阴离子是由流经KMP源中心管的水溶液在等离子体火焰中电离产生的,如NO3-。此外,解释了主要离子在多步碰撞诱导解离过程中特征碎片的形式,并在优化的条件下,使用锰的络合物阴离子二级质谱特征离子评估锰的检测限（LOD）为033 μg/L,线性动态范围涵盖至少2个数量级,在0~100 μg/L之间。因KMP源无Ar背景干扰,未来可将其与四极杆质谱结合,能够为水质检测提供新方法。     

Applying proteomics technology to platelet research

Platelets are small enucleated cells that circulate in the blood, where they play a key role in hemostasis and contribute to the formation of vascular plugs. Pathologically, they are involved in thrombosis and heart disease. Because platelets do not have a nucleus, proteomics offers a powerful way to approach their biology. Proteomics technology is based on the huge analytical power offered by mass spectrometry in combination with several separation techniques, such as two-dimensional gel electrophoresis (2DGE) or multidimensional liquid chromatography. Proteomics provides information about the complete set of proteins present in platelets, the platelet proteome, including post-translational variants. Over the last years, several research groups have applied proteomics to platelet research. A detailed analysis of the general proteome and signaling cascades in human platelets will improve our knowledge of platelet function, and thereby aid the development of new therapeutic agents to treat thrombotic diseases. This review presents the major advances in mass spectrometry-based proteomics techniques and their application to platelet research, and analyzes in detail the most relevant contributions to the field.     

The contribution of new dispersant mixed polymers to the economy of engine oils

Mixed polymers have been concentrated to produce highly concentrated VI improvers based on polyalkyl methacrylates (PAMA) and olefin copolymers (OCP). Because of their liquid form and special viscosity/temperature relationship, these concentrates can be stored, shipped and processed at comparatively low temperatures. This, in combination with a high specific activity, favours the economic manufacture of multigrade oils. In the VW elastomer compatibility test, the new dispersant mixed polymers (d-MP2) show absolutely neutral behaviour towards fluoroelastomers. In gasoline as well as in diesel engines they contribute noticeably to the dispersant potential, thus making it easier to comply with the requirements for API SH. Moreover, bench and road tests have revealed a major reduction of engine wear. The effect of different dispersant groups is compared by way of a simple laboratory test and an attempt is made at corroborating a hypothesis on wear reduction.     

Superconducting quantum interference device setup for magnetoelectric measurements

A commercial superconducting quantum interference device (SQUID) setup (MPMS 5S from Quantum Design), equipped with a magnetic ac susceptibility option, is modified for measurements of the linear magnetoelectric (ME) effect, i.e., of the magnetic moment induced by an applied external electric field in a ME sample. Test measurements on a Cr(2)O(3) (111) single crystal are in excellent agreement with previously reported data of its ME susceptibility. The main advantages of the proposed setup are the improved precision due to the high sensitivity of the SQUID magnetometer in combination with the lock-in technique and a relatively simple experimental realization.     

Fully automated intensity compensation for confocal microscopic images

One well-recognized problem in three-dimensional (3D) confocal microscopic images is that the intensities in deeper slices are generally weaker than those in shallower slices. The loss of intensity with depth hampers both qualitative observation and quantitative measurement of specimens. Two major types of methods exist to compensate for this intensity loss: the first is based on the geometrical optics inside the specimen, and the second applies an empirical parametric intensity decay function (IDF) of depth. A common feature shared by both methods is that they are parameter-dependent. However, for the optics-based method there are as yet no fully automated parameter-setting approaches; and for the IDF method the traditional profile-fitting approach cannot provide proper parameters if the presumed IDF model does not match the experimental intensity–depth profile of the 3D image. In this paper, we propose a novel maximum-entropy (ME) approach to fully automated parameter-setting. In principle the ME approach is suitable for any compensation method as long as it is parameter-dependent. The basic assumption is that without intensity loss an ideal 3D image should be generally homogeneous with respect to depth and this axial homogeneity can be represented by the entropy of a normalized intensity–depth profile. Experiments on real confocal images showed that such a profile was consistent with visual evaluation of axial intensity homogeneity and that the ME approach could provide proper parameters for both compensation methods mentioned above. Moreover, for the IDF method, experiments on both real and simulated data showed that the ME approach could provide more precise parameters than with traditional profile-fitting. The Appendix provides a proof that under certain conditions the global maximization of the profile-entropy is guaranteed.     

The use of X-ray photoelectron spectroscopy to estimate the stability of primary mass standards

Because it is still defined in terms of an artefact, the limit on the accuracy with which the SI unit of mass can be realised is largely limited by the surface stability of the kilogram standard. Not only is this true on the case of the International Prototype used to define the unit but also for national standard copies and indeed for mass standards in general. This paper describes the use of X-ray photoelectron spectroscopy (XPS) to study the accretion of contamination of the surfaces of standard masses. Angle Resolved X-ray photoelectron spectroscopy (AR XPS) was used to characterise the surfaces of platinum–iridium and stainless steel mass standards stored either in air or in vacuum, or which have been transferred between the two media. Various analysis methods for XPS data have been compared both in terms of providing an overlayer thickness on the mass standard and in terms of analysing the composition of this layer of contamination.     

Experimental Analysis and Wear Prediction Model for Unfilled Polymer–Polymer Sliding Contacts

Lifetime prediction of polymer–polymer contacts is a major challenge. Current design methods stemming from metal contact surfaces lack accuracy because polymers behave differently, especially regarding temperature variations. Experiments were performed on a pin-on-disk setup alternating static and rotating elements. Common unfilled engineering polymers, viz. polyoxymethylene (POM), polypropylene (PP), polyamide 6.6 (PA6.6), and polycarbonate (PC) were tested at ambient and elevated temperatures. Material combinations were analyzed regarding the effects of load, velocity, temperature, and the product of contact pressure and sliding velocity (PV limit). The experimental results show that the PV limit is not predictive for polymer–polymer contacts; rather, each material combination has a critical factor that determines the wear and frictional values and thus the contact’s durability and lifetime. The critical factor is the value of contact pressure or sliding velocity or temperature at which there is sudden increase in wear rate. The experimental results also demonstrate that the application temperature in operation has an important influence on the lifetime. A temperature increase can either be beneficial or have a negative impact depending on the material combination. Resulting from the extensive experimental analysis, a new design method, based on the principle of deformation energy, is proposed. The new model is different from existing models because it includes thermal properties of the materials in contact and it makes use of the Péclet number. Because the proposed model requires only data sheet values and design parameters to predict wear volume, the model improves the support of engineers in designing durable polymer–polymer sliding contacts.     

基于面向对象与STEP技术的制造环境模型研究

对制造环境模型的研究是ＣＩＭＳ新的研究领域。将面向对象技术与ＳＴＥＰ技术有机地结合起来，研究制造环境模型。不仅有效地支持基于数据模型的系统体系结构的发展，而且是实现ＣＩＭＳ信息完整而一致的描述与交换的重要基础性工作。     

并行工程下CAPP工艺决策加工元模型研究

提出了面向并行工程下产品设计的ＣＡＰＰ工艺决策加工元模型,并讨论了基于该模型的零件加工工艺性分析问题。应用该模型、可以将工艺决策与产品设计有机结合且符合工艺设计分阶段、分层次,从局部到全局,从主要到次要的渐进循环规律。     

生物样品中醇类代谢物的化学衍生化质谱分析方法研究进展

生物样品的代谢组学是近年来质谱领域的研究热点.醇类代谢物是生物样品非常重要的一类代谢物,主要包括脂肪醇、糖类、酚类、甘油酯类以及甾醇等.这些代谢物在体内承担着各种重要的生理学功能.然而,由于大多数醇类代谢物极性较低,缺乏易于离子化的基团,其在质谱领域的研究比胺类、酸类等代谢物少.化学衍生化技术通过设计靶向某官能团的有机...     

Study on denoising filter of underwater vehicle using DWT

In the step processing a digitalized signal,noises are generated by internal or external causes of the system.In order to eliminate these noises,various methods are researched.Among these noise elimination methods,Fourier fast transform （FFT） and short-time Fourier transform （STFT） are widely used.Because they are expressed as a fixed time-frequency domain,they have the disadvantage that the time information about the signal is unknown.In order to overcome these limitations,by using the wavelet transform that provides a variety of time-frequency resolution,multi-resolution analysis can be analysed and a varying noise depending on the time characteristics can be removed more efficiently.Therefore,in this paper,a denoising method of underwater vehicle using discrete wavelet transform （DWT） is proposed.     

Evaluation of grinding wheel loading phenomena by using acoustic emission signals

In the industrial manufacturing field, machining is a major process. Machining operations involve grinding, drilling, milling, turning, pressing, molding, and so on. Among these operations, grinding is the most precise and complicated process. The surface condition of the grinding wheel plays an important role in grinding performance, and the identification of grinding wheel loading phenomena during the grinding process is critical. Accordingly, this present study describes a measurement method based on the acoustic emission (AE) technique to characterize the loading phenomena of a Si₂O₃ grinding wheel for the grinding mass production process. The proposed measurement method combines the process-integrated measurement of AE signals, offline digital image processing, and surface roughness measurement of the ground workpieces for the evaluation of grinding wheel loading phenomena. The experimental results show that the proposed measurement method provides a quantitative index from the AE signals to evaluate the grinding wheel loading phenomena online for the grinding mass production process, and this quantitative index is determined via some experiments in advance in the same grinding environment to help the monitoring and controlling of the grinding process.     

Plastic limit analysis with non linear kinematic strain hardening for metalworking processes applications

Limit analysis approaches are widely used to deal with metalworking processes analysis; however, they are applied only for perfectly plastic materials and recently for isotropic hardening ones excluding any kind of kinematic hardening. In the present work, using Implicit Standard Materials concept, sequential limit analysis approach and the finite element method, our objective consists in extending the limit analysis application for including linear and non linear kinematic strain hardenings. Because this plastic flow rule is non associative, the Implicit Standard Materials concept is adopted as a framework of non standard plasticity modeling. The sequential limit analysis procedure which considers the plastic behavior with non linear kinematic strain hardening as a succession of perfectly plastic behavior with yielding surfaces updated after each sequence of limit analysis and geometry updating is applied. Standard kinematic finite element method together with a regularization approach is used for performing two large compression cases (cold forging) in plane strain and axisymmetric conditions.     

隐式极限状态方程可靠性分析的加权响应面法

针对隐式极限状态方程的可靠性分析,提出加权回归响应面法,该方法采用线性响应面来拟合隐式极限状态方程。所提方法的策略可以归结为三点,一是选取极限状态函数绝对值更小的实验抽样点;二是根据每个实验抽样点的极限状态函数绝对值的大小,构造每个点在回归分析中的权数,增强极限状态函数绝对值小的实验抽样点对响应面函数确定的作用,削弱极限状态函数绝对值大的实验抽样点对响应面函数确定的作用;三是采用与传统响应面法一样的向设计点收敛的迭代方法。这三点策略保证了所得到的线性响应面函数能够在设计点附近更好地拟合真实隐式极限状态函数值为零的表面,从而达到高精度计算隐式极限状态方程可靠度指标的目的,算例结果充分显示所提方法的优越性。文中所提方法与组合响应面法结合,可以发展成为非线性高变异性隐式极限状态方程失效概率计算的高精度方法。     

Residual stress-induced warping in direct metal solid freeform fabrication

Tolerance loss due to residual stress-induced warping is a major concern in solid freeform fabrication (SFF) processes, particularly those which involve direct deposition of molten metals. An understanding of how residual stresses develop and how they lead to tolerance loss is a key issue in advancing these processes. In this paper, results are presented from warping experiments on plate-shaped specimens created by two direct metal deposition methods, which are utilized by a particular SFF process termed shape deposition manufacturing (SDM). Results from these experiments give insight into the differences between the two deposition methods, the role of preheating and insulating conditions during manufacture and the influence of deposition path on magnitudes and distributions of warping displacements. Results are then compared to numerical predictions from both one and two-dimensional residual stress models, which are applicable to SDM and similar direct metal deposition processes. Results from the experiments and numerical models suggest that a combination of initial substrate preheating and part insulation can be applied to SDM and similar SFF processes to limit warping deflections, which is substantially simpler than active control of part temperatures during manufacture. Results also suggest that 3-D mechanical constraints are important in achieving precise control of warping behavior in SFF processes.     

Studies on Degradation Mechanisms of Tape Lubricants in a High Vacuum Environment

Degradation and tribological performance of several tape lubricants were studied during sliding in a high vacuum environment. Gaseous products generated from the head–tape interface and friction force were detected and monitored as function of sliding distance by using a quadrupole mass spectrometer and strain gauges. Chemical analyses of the commercial tape lubricants were done to better understand the degradation processes and degradation products in the sliding tests. Experimental results showed that the commercial metal evaporated (ME) tape lubricants include fatty acid and perfluoropolyether (PFPE) compounds. The degradation products from the commercial tape include small fluorine containing fragments from the PFPE lubricant and small hydrocarbon fragment from fatty acid. In addition, three other species, H₂, C₂H₅ and CO₂ were detected in the case of ME tapes and they were generated from the degradation of the diamond-like carbon (DLC) coating on the tape surface. The commercial metal-particle (MP) tape used fatty acid and fatty acid ester lubricants. Only hydrocarbon fragments were detected in the MP tapes' sliding tests, no H₂, C₂H₅ and CO₂ were found. The coefficient of friction of these two tapes increased with sliding and depletion of lubricant on the tape surface. The trend of the coefficient of friction was different for ME and MP tapes because of the differences in the lubricant and lubricant distribution on these two tape surfaces. Z-Dol and stearic acid were used to lubricate ME tapes, their test results were analyzed and compared with the commercial tapes' test results.     

Development and application of thermo-oxidation laboratory tests. Correlations with engine lubricant specifications

Laboratory simulation tests are an important stage in the selection of engine lubricants. Where these tests are brief and repeatable, they allow numerous studies and can provide a wide range of information. They are all the more valuable if they have a close degree of correlation with a specification test. The IIID high temperature oxidation test, the ME 1517 oxidation laboratory test and the Renault 30 diesel engine test are examples of specifications for the formulation of engine lubricants. The aim of the present study has been to find or develop a brief, repeatable laboratory test for these specifications and to establish a correlation between the test and the specification. Data obtained show satisfactory correlations between the TFOUT (Thin Film Oxygen Uptake Test) and the IIID sequence, the open oxidation laboratory test COST (24 h) and ME 1517 (192 h), and the ELF/ECL microcoking test and the Renault 30 turbo diesel test.     

基于马尔可夫链样本模拟的线抽样方法研究

针对工程中常见的多变量、小失效概率的隐式非线性极限状态方程的可靠性分析问题,提出马尔可夫链样本模拟与线抽样相结合的高效数字模拟法.所提方法采用马尔可夫链快速得到失效域中的样本,并依据这些样本获取线抽样的重要方向,然后再采用线抽样技术在重要方向上进行抽样,进而得到失效概率的高效估计.与传统的有限差分法相比,基于马尔可夫链的重要方向获取方法具有结果准确和稳定的优点.将文中方法用于分析多级循环载荷作用下某发动机涡轮盘的低周疲劳寿命的可靠性,结果表明所提方法对于高维、小失效概率的可靠性分析是有效可行的.     

Freeze-etching of dispersions without contamination of the fracture faces.

The physical processes occuring while the fracture face of a dispersion is being freeze-etched are described and the resulting opportunities for elimination of contamination phenomena are discussed. An anticontamination device which can be used in combination with a drop freeze-fracture apparatus is described. The main advantages of the device, high effectiveness and great simplicity, are demonstrated by several practical examples.     

Natural frequency extraction of a beam-moving mass system with periodic passages using its pseudo-natural frequencies

Wind turbines, helicopters, and turbo-machineries’ rotary motion, along with a variety of nonlinear structures linearized with their periodic limit cycles, may all contain time-periodic terms in their equations of motion even if the equations remain linear. The purpose of this study is to model these systems into a beam-moving mass system. Natural frequencies of the beam are calculated using past work in which pseudo-natural frequencies of a beam-moving mass system were extracted, followed by the homotopy perturbation method. The findings of this study are valuable to the industry, and they decrease error margin in resonance range assessment. This approach indicates that for beam-moving mass systems, extraction of natural frequencies that ignore the moving mass effect can lead to inaccurate results, whereas only a limited amount of physical data are needed obtain accurate calculations. Furthermore, this study used homotopy perturbation for operational modal analysis purposes and not for solving nonlinear equations.