Bipolar ion detector based on sequential conversion reactions

This work demonstrates the feasibility of a novel scintillation detector with greater detection efficiency than that of chevron-type microchannel plate (MCP) detectors. The detection mechanism involves sequential conversion reactions induced by ion-surface impacts. Identical detection conditions can be utilized to monitor both positive and negative ions in mass spectrometers. The proposed detector comprises an ion beam guiding device, a negatively biased washer-shaped conversion dynode, and an aluminum-coated scintillation detector. The beam guide changes the electric field around the washer-shaped conversion dynode, and it allows the primary and secondary ions to propagate toward the scintillation phosphor and the conversion dynode, respectively. The detection is achieved by the detection of electron-induced luminescence on a phosphor. The amplification efficiency of this bipolar ion detector increases as the conversion dynode voltage increases. For ions with a mass-to-charge ratio of up to 90 000, the sensitivity of the BID is 1.4-14.4 times that of the MCP. Further improvement of the sensitivity can be achieved by increasing the conversion dynode voltage or the ion acceleration voltage. Results of this study demonstrate that this detector is a promising alternative for efficient ion detection.     

An integrated approach to document decomposition and structural analysis

A document image is a visual representation of a paper document, such as a journal article page, a cover page of facsimile transmission, office correspondence, an application form, etc. Document image understanding as a research endeavor consists of developing processes for taking a document through various representations, from scanned image to semantic representation. This article describes document decomposition and structural analysis, which constitutes one of the major processes involved in document image understanding. The current state of the art and future directions in the areas of document segmentation, layout analysis, and logical block grouping are indicated. A system that performs decomposition and structural analysis (including logical grouping and read-order determination) on complex multiarticled documents is presented. This system uses bottom-up segmentation techniques to identify the block structure of a document, and layout rules to classify and group these blocks into logical units that represent meaningful subdivisions of the document. Experimental results showing the efficiency of this approach are presented and discussed. © 1996 John Wiley & Sons, Inc.     

Plastic ELISA-on-a-chip based on sequential cross-flow chromatography

A plastic chip that can perform immunoassays using an enzyme as signal generator, i.e., ELISA-on-a-chip, was developed by incorporating an immunostrip into channels etched on the surfaces of the chip. To utilize an analytical concept of cross-flow chromatography, the chip consisted of two cross-flow channels in the horizontal and vertical directions. In the vertical channel, we placed a 2-mm-wide immunostrip for cardiac troponin I (cTnI), which was identical to a conventional rapid test kit except for the utilization of an enzyme, horseradish peroxidase (HRP), as tracer. An enzyme substrate supply channel and a horizontal flow absorption pad compartment were transversely arranged on each lateral side of the signal generation pad of the strip, respectively. Upon application of a sample containing cTnI, it migrated vertically through the membrane strip by capillary action, and antigen-antibody binding occurred. After 15 min, the horizontal flow was initiated by the addition of a chromogenic substrate solution for HRP into the supply channel and by partial superimposition of the horizontal flow absorption pad onto the signal generation pad. A color signal proportional to the analyte concentration was produced on this pad, measured after 5 min as optical densities using a digital camera-based detector, and quantified by integration of the densities under the peak after normalization. Its calibration curve indicated that the detection limit of the chip was approximately 0.1 ng/mL and its quantification limit was 0.25 ng/mL. In measuring blindly prepared samples, the chip performance correlated with that of a reference system, Beckman Coulter Access, within 2.5-fold discrepancy at the detection limit.     

Extractive solubilization, structural change, and functional conversion of cytochrome c in ionic liquids via crown ether complexation

This article reports on the extraction behavior of heme proteins from an aqueous phase into ionic liquids (ILs) with dicyclohexano-18-crown-6 (DCH18C6), and the structure-function relationship of cytochrome c (Cyt-c) dissolved in ILs. We have found that DCH18C6 enables transfer of Lys-rich proteins into ILs via supramolecular complexation. The hydrophobicity and functional groups of ILs have a great influence on protein partitioning, and a hydroxyl group-containing IL with DCH18C6 is capable of the quantitative partitioning of Cyt-c. On the other hand, protein transfer using conventional organic solvents is negligibly small. UV-visible, CD, and resonance Raman spectroscopic characterizations indicate that the sixth ligand Met 80 in the heme group of the Cyt-c-DCH18C6 complex in IL is replaced by other amino acid residues of the peptide chain and that a non-natural, six-coordinate, low-spin ferric heme structure is induced in IL. Solubilization of Cyt-c in IL causes the environmental change of the heme vicinity of Cyt-c, which triggers the functional conversion of Cyt-c from an electron-transfer protein to peroxidase. The Cyt-c-DCH18C6 complex in IL provides remarkably high peroxidase activity compared with native Cyt-c, because of enhancement of the affinity for H2O2.     

An asymptotic matching approach to shallow-notched structural elements

Fracture in brittle material specimens with V-notches is satisfactorily described assuming as governing parameter the generalized (or notch) stress intensity factor, whose anomalous physical dimensions depend on the notch opening angle. Its critical value, i.e. the generalized toughness, can then be linked to the material strength and toughness according to a number of fracture criteria available in the literature. However, all these criteria provide an infinite failure load as the notch depth tends to zero, this undesirable property being shared with Linear Elastic Fracture Mechanics when applied to vanishing cracks. Aim of the present paper is to overcome this shortcoming. The analysis of the notched specimens is carried out by means of a multiscale approach according to which the problem is solved separately in the region far away from the notch (the outer field) and in the region close to the notch (the inner field). Hence, the asymptotic matching technique can be exploited to achieve the overall solution. Although the procedure is general, i.e. it may be applied to any notch shape, numerical computations refer to sharp V-notches with a re-entrant corner equal to 120°. Comparison with experimental data obtained by testing polystyrene specimens turns out to be more than satisfactory.     

An implicit enumeration approach to tolerance allocation in sequential tolerance control

The accuracy and precision of a manufactured dimension is largely dependent on the accuracy and precision of the technological processes selected for its execution. It is not unusual to have available several competing technological processes for execution of each manufacturing operation specified in a process plan, where it is generally assumed that as the precision of the technological process improves, the associated cost and yield of the operation increase. This paper presents an implicit enumeration approach to the selection of an optimum subset of technological processes required to execute a process plan under a. sequential (or adaptive) tolerance control strategy.     

A unified parametric design approach to structural shape optimization

This paper presents a general parametric design approach for 2-D shape optimization problems. This approach has been achieved by integrating practical design methodologies into numerical procedures. It is characterized by three features: (i) automatic selection of a minimum number of shape design variables based on the CAD geometric model; (ii) integration of sequential convex programming algorithms to solve equality constrained optimization problems; (iii) efficient sensitivity analysis by means of the improved semi-analytical method. It is shown that shape design variables can be either manually or systematically identified with the help of equality constraints describing the relationship between geometric entities. Numerical solutions are performed to demonstrate the applicability of the proposed approach. A discussion of the results is also given:     

结构时域识别的超单元法

在实际应用中 ,传感器数目通常远远小于结构模型自由度的数目。而为了实现识别结果的唯一性 ,一般的时域识别方法要求测量信息是完备的。由于超单元法的分散识别能力 ,使得该方法可以在传感器数目有限的情况下实现大型结构的识别。首先建立了超单元模型 ,其次提出了对超单元模型进行参数化的方法 ,针对结构识别中的荷载未知问题对超单元的划分进行了讨论。最后用大型结构的识别算例对整体识别方法和超单元识别方法进行了比较。结果表明 :超单元法不但可以在传感器数目有限的情况下实现结构参数的完整识别 ,而且其识别效率远远高于一次完成型算法。     

Phosphoprotein isotope-coded affinity tag approach for isolating and quantitating phosphopeptides in proteome-wide analyses

A method has been developed that utilizes phosphoprotein isotope-coded affinity tags (PhIAT) that combines stable isotope and biotin labeling to enrich and quantitatively measure differences in the O-phosphorylation states of proteins. The PhIAT labeling approach involves hydroxide ion-mediated beta-elimination of the O-phosphate moiety and the addition of 1,2-ethanedithiol containing either four alkyl hydrogens (EDT-D0) or four alkyl deuteriums (EDT-D4) followed by biotinylation of the EDT-D0/D4 moiety using (+)-biotinyl-iodoacetamidyl-3,6-dioxaoctanediamine. The PhIAT reagent, which contains the nucleophilic sulfhydryl and isotopic label covalently linked to a biotin moiety, was synthesized and has the potential utility to reduce the O-phosphorylation derivatization into a one-step process. The PhIAT labeling approach was initially demonstrated using the model phosphoprotein beta-casein. After proteolytic digestion, the PhIAT-labeled peptides were affinity isolated using immobilized avidin and analyzed using capillary reversed-phase liquid chromatography-mass spectrometry. PhIAT-labeled beta-casein peptides corresponding to peptides containing known sites of O-phosphorylation were isolated and identified. The PhIAT labeling method was also applied to a yeast protein extract. The PhIAT labeling technique provides a reliable method for making quantitative measurements of differences in the O-phosphorylation state of proteins.     

A scientometric approach to autism based on translation sociology

We advance the following hypothesis with respect to the construction of scientific knowledge: a) a scientific article may be seen as bringing together differing knowledge networks within the same experimental context; b) the researcher attempts to prove the existence of objective links within this context. This process allows the researcher to link or associate his own subjective proposals to those that are verifiably objective relationships for all researchers. Researchers consolidate the relationships put forward by others accordingly. There is a statistic method which makes it possible to demonstrate these dynamics, i.e., co-word analysis. This method, applied to articles on autism, has provided results that support this hypothesis. The methods brought to bear by the majority of researchers follow these general dynamics.     

一种高效的基于位图序列模式挖掘算法

为实现在大型事务数据库中挖掘有价值的序列数据,提出了一种基于位图的高效的序列模式挖掘算法(SMBR)。SMBR算法采用位图表示数据库的方法,提出一种简化的位图表示结构。该算法首先由序列扩展和项扩展产生候选序列,然后通过原序列位图和被扩展项位图位置快速运算生成频繁序列。实验表明,应用于大型事务数据库,该方法不仅能有效地提高挖掘效率,而且挖掘处理过程中产生的临时数据所需的内存大大降低,能够高效地挖掘序列模式。     

A structural approach to the calculation of j

The calculation of the elastic-plastic fracture parameter, J, is often assumed to demand finite element analysis, particularly when the loads applied are secondary, or partly secondary, in nature, e.g. thermal load. However, it is shown that a simple technique based on the reference stress approach can be used to calculate J even in these cases. Example results are given, and compare well with finite element solutions.     

An alternative approach to the evaluation of plant structural efficiency

The aim of this paper is to present an approach for the evaluation of plant structural efficiency. The essence of the approach is a cost comparison of an observed plant structure for a multi-plant firm and an optimal plant structure under static conditions. The comparison makes use of a mixed-integer location model and of empirical evidence from scale economies studies. The application of this approach to a representative multi-plant firm in the German brewing industry shows that under the given assumptions the observed plant structure is inefficient.     

Study of component structural equivalent fatigue based on a combined stress gradient approach and the theory of critical distance

Fatigue limit load is one of the most important factors and concerns in designing and manufacturing critical mechanical parts such as crankshafts. Traditionally, this governing parameter is obtained via a time and money-consuming experiment and analysis of a simple structure while it becomes theoretically complicated for sophisticated cases. In this paper, proper extrapolation methods to calculate the stress gradient in the stress concentration area are first chosen to obtain the material parameter using the theory of critical distance (TCD) indirectly. Then the fatigue limit load of crankshafts with the same material properties but different structures are computed. Validation between the prediction and the experimental results shows that this combined approach may provide a more satisfactory result in terms of fatigue limit for quick engineering prediction.     

基于语言评价信息的多方案选优研究

通过LWD和LOWA算子,给出了一种算法。该算法在预先定义语言短语排序的情况下,可将专家群给出的多个指标下多个方案的语言评价信息集结为对方案的语言短语排序,从而可选出最优方案,并通过仿真算例,证明了该方法的有效性。     

Phenomenological approach to building materials development based on physicochemical analysis

This paper examines the main principles of a phenomenological approach to building materials development in terms of the conceptual—cognitive system property—composition—structure—process based on Kurnakov’s physicochemical analysis.     

An approach to accidents modeling based on compounds road environments

The most common approach to study the influence of certain road features on accidents has been the consideration of uniform road segments characterized by a unique feature. However, when an accident is related to the road infrastructure, its cause is usually not a single characteristic but rather a complex combination of several characteristics. The main objective of this paper is to describe a methodology developed in order to consider the road as a complete environment by using compound road environments, overcoming the limitations inherented in considering only uniform road segments. The methodology consists of: dividing a sample of roads into segments; grouping them into quite homogeneous road environments using cluster analysis; and identifying the influence of skid resistance and texture depth on road accidents in each environment by using generalized linear models. The application of this methodology is demonstrated for eight roads. Based on real data from accidents and road characteristics, three compound road environments were established where the pavement surface properties significantly influence the occurrence of accidents. Results have showed clearly that road environments where braking maneuvers are more common or those with small radii of curvature and high speeds require higher skid resistance and texture depth as an important contribution to the accident prevention.     

基于序贯蒙特卡洛法的自相关过程控制

针对参数未知的自相关过程在线质量控制问题,研究了基于序贯蒙特卡洛法(SMC)的过程控制策略。在给出过程状态空间方程模型的基础上,分析了由于参数未知使得运用Kalman滤波求解控制策略时存在的困难;通过设置未知参数的先验分布,运用序贯蒙特卡洛法得到各参数的后验估计,进而获得了使过程损失最小的控制策略。给出了仿真,以分析控制策略的有效性,结果表明所得到的控制策略具有较好的控制效果。     

Efficient and monolithic polarization conversion system based on a polarization grating

We introduce a new polarization conversion system (PCS) based on a liquid-crystal polarization grating (PG) and louvered wave plate. A simple arrangement of these elements laminated between two microlens arrays results in a compact and monolithic element, with the ability to nearly completely convert unpolarized input into linearly polarized output across most of the visible bandwidth. In our first prototypes, this PG-PCS approach manifests nearly 90% conversion efficiency of unpolarized to polarized for ±11° input light divergence, leading to an energy efficient picoprojector that presents high efficacy (12 lm/W) with good color uniformity.     

All-optical analog-to-digital conversion scheme based on Sagnac loop and balanced receivers

An all-optical analog-to-digital conversion scheme based on a Sagnac loop and balanced receivers is proposed and experimentally demonstrated. Adjustable phase shift about the transfer function of the Sagnac loop is obtained by using the multiwavelength optical pulses to realize the phase-shift optical quantization. Benefit from the complementary outputs at the transmitted and reflected ports of the Sagnac loop and balanced receiver can be used to obtain the quantized output binary signal for the encoding operation. A proof-of-concept experiment is implemented using a wavelength tunable continuous-wave laser diode. Using 16 different wavelengths, the 16 quantization levels are demonstrated and an effective number of bits (ENOB) of 4?bits is obtained.