Effects of illumination during anodization of porous silicon

The effects of illumination during anodic etching of porous Si have been studied. For a fixed current density and anodization time, it has been observed that below a critical irradiance level, increasing the radiant flux density during anodization results in higher photoluminescence and a blue shift of the photoluminescence spectra. For irradiance above the critical value, the photoluminescence intensity decreases. Transmission Fourier-transform infrared spectroscopy, x-ray photoelectron spectroscopy and atomic force microscopy have been employed to investigate the effects of illumination on the characteristics of porous Si.     

A unified least-squares approach to the evaluation of geometric errors using discrete measurement data

This paper presents a unified least-squares approach to the best fit of geometric features and evaluation of dimensional errors. The study originated from the need for advanced algorithms for the dimensional measurement of high precision manufactured parts. The proposed algorithm differs from traditional least-squares in that no linearization or approximation is employed and that it is general to all kinds of geometric features. Instead of computing a substitute best fit feature, the algorithm inversely transforms the measurement coordinates to best fit the nominal geometry. The sum of the squared errors in the surface normal direction is thus minimized with respect to the parameters of a rigid body transformation. Form tolerances are then evaluated using the peak-to-valley deviations after the best fit. To examine the uncertainty of the transformation obtained, sensitivity analysis was investigated to relate transformation errors to dimensional errors. A sensitivity measure is used to estimate the joint effect of the measurement locations and the number of measurement data on the accuracy of the coordinate transformation. Computer simulations have been performed on different geometric features to study the robustness and efficiency of the algorithm. Application to the measurement of high precision fuel injectors is also presented.     

Fast Bezier interpolator with real-time lookahead function for high-accuracy machining

This study presents a real-time fast Bezier interpolation method that solves linearly segmented contour problems that occur during milling using conventional CNC machines. Depending on the length and the CSB criterion, these linearized segments can be regarded as noise, continuous short blocks (CSBs), or G01 blocks. The CSB criterion proposed in this paper is employed to identify CSBs during the NC code interpreting stage. The CSBs are fitted into cubic Bezier curves and interpolated to produce smoother contours in real-time machining. Two different NC programs possessing a large number of short blocks were tested on our PC-based real-time control system. Simulations and experimental results demonstrate that the proposed fast Bezier interpolator (FBI) with real-time lookahead function provides satisfactory performance.     

Finite dimensional filters with non-linear drift IX Construction of finite dimensional estimation algebras of non-maximal rank

The idea of using estimation algebra to construct finite-dimensional nonlinear filters was first proposed by Brockett and Mitter independently. It has proven to be an invaluable tool in the study of nonlinear filtering problem. In 1983, Brockett proposed to classify all finite-dimensional estimation algebras. In this paper, we give the construction of finite-dimensional estimation algebras of non-maximal rank. These non-maximal rank finite-dimensional estimation algebras play an important role in Brockett's classification problem.     

Incorporation of [1-14C]-oleic acid into neutral glycerides and phosphoglycerides of mouse brain

The incorporation of [1-¹⁴C]-oleic acid into the neutral glycerides and phosphoglycerides of adult mouse brain was examined between 1 and 80 min after intracerebral injection. Radioactivity of the free oleic acid in brain decreased rapidly with a half-life of ca. 5 min. The specific radioactivity of the phosphatidic acids was highest at 1 min after injection. This was followed by the diacylglycerols and triacylglycerols which attained a maximum specific radioactivity at 3 and 20 min after injection, respectively. Specific radioactivities of the neutral glycerides were higher than the phosphoglycerides. A larger proportion of the radioactivity in the diacylglycerols was transferred to the phosphoglycerides than to the triacylglycerols. Among the phosphoglycerides, radioactivity was actively incorporated into the inositol phosphoglycerides. The specific radioactivity of the inositol phosphoglycerides was higher than the diacylsn-glycero-3-phosphorylcholines, and the kinetics of incorporation of radioactivity into these lipids was also different. A water soluble material was found which showed maximum specific radioactivity at 6–10 min after injection. The properties of this water soluble material suggested that it may be an intermediate involved in the acyl group metabolism of phosphoglycerides in brain.     

Preparation of O‐carboxymethyl chitosans and their effect on color yield of acid dyes on silk

O‐Carboxymethyl chitosans with a low degree of substitution (DS) and a high degree of deacetylation (DD) were prepared directly from chitin and characterized by using ¹H‐NMR, ¹³C‐NMR, and elemental analysis methods. In our study, O‐carboxymethyl chitosans could increase the color yield of Acid Red 44 and Acid Green 25 on silk fabrics without lowering the corresponding washing fastness property. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2500–2502, 2003     

Thermionic emission of amorphous diamond and field emission of carbon nanotubes

Thermal-field emission characteristics from nano-tips of amorphous diamond and carbon nanotubes at various temperatures are reported in this study. Amorphous diamond emitted more than 13 times more electrons at a temperature of 300 °C than at room temperature. In contrast, CNTs exhibited no increase of emitted current upon heating to 300 °C. The thermally agitated emission of amorphous diamond is attributed to the presence of defect bands. The formation of these defect bands raises the Fermi level into the upper part of the band gap, and thus reduces the energy barrier that the electrons must tunnel through. From defect bands within the band gap, the conduction band electrons were significantly increased due to electron tunnels from defect bands. The enhanced thermal-field emission originating from defect bands was observed in this study. This thermally agitated behavior of field emission for amorphous diamond was highly reproducible as observed in this research.     

Development of Situation-Aware Applications in Services and Cloud Computing Environments

Computing paradigms have evolved towards integrating small and personal computing devices with large-scale and resource-sharing computing infrastructures, such as services and cloud computing (SCC) platforms during the past two decades to provide users anytime, anywhere computing capability with more flexibility, richer computing resources, more cost-effectiveness, lower risks of system failures, and less management and maintenance effort. Situation-aware (SA) applications in SCC environments have the capability to adapt SCC systems to situation changes to facilitate better human-computer interactions and continuous system availability, and satisfactory quality-of-service (QoS) for the applications. Mission-critical applications in many domains usually require situation awareness, and have started to incorporate it in SCC platforms due to the need of rapidly reconfiguring and integrating systems owned and operated by various organizations for sharing information and coordinating operations. In this paper, the concepts and characteristics of SCC and situation awareness (SAW), and the challenges and current state of the art in developing SA applications in SCC environments are discussed. Our research in this area, including the development of Adaptable Situation-aware Secure Service-based (AS3) systems and Adaptive Service-Based Systems (ASBS) with QoS Monitoring and Adaptation (M/A), is presented. Future research in this area is discussed.     

DNA sequence comparison by a novel probabilistic method

This paper proposes a novel method for comparing DNA sequences. By using a graphical representation, we are able to construct the probability distributions of DNA sequences. These probability distributions can then be used to make similarity studies by using the symmetrised Kullback-Leibler divergence. After presenting our method, we test it using six DNA sequences taken from the threonine operons of Escherichia coli K-12 and Shigella flexneri. Our approach is then used to study the evolution of primates using mitochondrial DNA data. Our method allows us to reconstruct a phylogenetic tree for primate evolution. In addition, we use our technique to analyze the classification and phylogeny of the Tomato Yellow Leaf Curl Virus (TYLCV) based on its whole genome sequences. These examples show that large volumes of DNA sequences can be handled more easily and more quickly by our approach than by the existing multiple alignment methods. Moreover, our method, unlike other approaches, does not require human intervention, because it can be applied automatically.