Integrated starter generator for 42-V powernet using induction machine and direct torque control technique

This paper describes an integrated starter generator (ISG) for automobile applications with 42-V powernet. This system is based on an induction machine which is directly mounted on the engine crankshaft and controlled using the technique of direct torque control (DTC). The suitability of the technique for ISG application is explained. The control structure of DTC for ISG application is described. Detailed experimental results from a 1.4-1 diesel engine are presented demonstrating the performance of the system during cranking as well as generation. The ISG also incorporates the feature of "on the fly start" during generation mode. Details of a low voltage high current power converter developed for this application are also given.     

Optical and microstructural investigations of porous silicon

Raman scattering and photoluminescence (PL) measurements on (100) oriented n-type crystalline silicon (c-Si) and porous silicon (PS) samples were carried out. PS samples were prepared by anodic etching of c-Si under the illumination of light for different etching times of 30, 60 and 90 min. Raman scattering from the optical phonon in PS showed the redshift of the phonon frequency, broadening and increased asymmetry of the Raman mode on increasing the etching time. Using the phonon confinement model, the average diameter of Si nanocrystallites has been estimated as 2.9, 2.6 and 2.3 nm for 30, 60 and 90 min samples, respectively. Similar size of Si crystallites has been confirmed from the high resolution transmission electron microscopy (HRTEM). Using 2TO phonon mode intensity, we conjectured that the disordered Si region around the pores present in 30 min PS dissolved on etching for 90 min. The photoluminescence (PL) from PS increased in intensity and blue shifted with etching time from 2.1–2.3 eV. Blue shifting of PL is consistent with quantum confinement of electron in Si nanocrystallites and their sizes are estimated as 2.4, 2.3 and 2.1 nm for 30, 60 and 90 min PS, respectively which are smaller than the Raman estimated sizes due to temperature effect. Unambiguous dominance of quantum confinement effect is reported in these PS samples.     

Generating discriminating cartoon faces using interacting snakes

As a computational bridge between the high-level a priori knowledge of object shape and the low-level image data, active contours (or snakes) are useful models for the extraction of deformable objects. We propose an approach for manipulating multiple snakes iteratively, called interacting snakes, that minimizes the attraction energy functionals on both contours and enclosed regions of individual snakes and the repulsion energy functionals among multiple snakes that interact with each other. We implement the interacting snakes through explicit curve (parametric active contours) representation in the domain of face recognition. We represent human faces semantically via facial components such as eyes, mouth, face outline, and the hair outline. Each facial component is encoded by a closed (or open) snake that is drawn from a 3D generic face model. A collection of semantic facial components form a hypergraph, called semantic face graph, which employs interacting snakes to align the general facial topology onto the sensed face images. Experimental results show that a successful interaction among multiple snakes associated with facial components makes the semantic face graph a useful model for face representation, including cartoon faces and caricatures, and recognition.     

Parallel implementation of time-dependent density functional theory

We present a massively parallel implementation of time-dependent density functional theory in real space, aimed at computing optical absorption spectra of realistic systems with hundreds of atoms from first principles. We provide details of the formalism and discuss its implementation, optimization, and efficient parallelization, as well as remaining limitations, in detail. The capabilities of the code are illustrated by calculations of optical properties of hydrogenated silicon quantum dots.     

Integrating faces and fingerprints for personal identification

An automatic personal identification system based solely on fingerprints or faces is often not able to meet the system performance requirements. We have developed a prototype biometrics system which integrates faces and fingerprints. The system overcomes the limitations of face recognition systems as well as fingerprint verification systems. The integrated prototype system operates in the identification mode with an admissible response time. The identity established by the system is more reliable than the identity established by a face recognition system. In addition, the proposed decision fusion scheme enables performance improvement by integrating multiple cues with different confidence measures. Experimental results demonstrate that our system performs very well. It meets the response time as well as the accuracy requirements     

Design and analysis of a video-on-demand server

The availability of high-speed networks, fast computers and improved storage technology is stimulating interest in the development of video on-demand services that provide facilities similar to a video cassette player (VCP). In this paper, we present a design of a video-on-demand (VOD) server, capable of supporting a large number of video requests with complete functionality of a remote control (as used in VCPs), for each request. In the proposed design, we have used an interleaved storage method with constrained allocation of video and audio blocks on the disk to provide continuous retrieval. Our storage scheme interleaves a movie with itself (while satisfying the constraints on video and audio block allocation. This approach minimizes the starting delay and the buffer requirement at the user end, while ensuring a jitter-free display for every request. In order to minimize the starting delay and to support more non-concurrent requests, we have proposed the use of multiple disks for the same movie. Since a disk needs to hold only one movie, an array of inexpensive disks can be used, which reduces the overall cost of the proposed system. A scheme supported by our disk storage method to provide all the functions of a remote control such as “fast-forwarding”, “rewinding” (with play “on” or “off”), “pause” and “play” has also been discussed. This scheme handles a user request independent of others and satisfies it without degrading the quality of service to other users. The server design presented in this paper achieves the multiple goals of high disk utilization, global buffer optimization, cost-effectiveness and high-quality service to the users.     

Optimal registration of object views using range data

This paper deals with robust registration of object views in the presence of uncertainties and noise in depth data. Errors in registration of multiple views of a 3D object severely affect view integration during automatic construction of object models. We derive a minimum variance estimator (MVE) for computing the view transformation parameters accurately from range data of two views of a 3D object. The results of our experiments show that view transformation estimates obtained using MVE are significantly more accurate than those computed with an unweighted error criterion for registration     

Variations on the Theme of Scarf's Counter-Example

We study the relation between the stability of a competitive equilibrium (CE)and the price adjustment mechanism used to attain that equilibrium point.Using two specific examples, a three-commodity exchange economy with a uniquecompetitive equilibrium (Scarf's global instability example) and atwo-commodity, two-trader type exchange economy with multiple competitiveequilibria, we show that the stability of a CE depends critically upon thedynamics of the price adjustment mechanism. A particular CE may be unstableunder one price adjustment mechanism but stable under another. The jointdynamics of the chosen price adjustment mechanism and the given economydetermines the overall stability of its competitive equilibrium. Our resultssuggest that context-rich studies of economic systems which focus on aspecific price adjustment mechanism may provide insights into the dynamics andstability of economic systems that are often not revealed through acontext-independent analysis.     

涡旋式压缩机中的蒸气喷射

这篇论文定量分析了在应用于空调及制冷场合时，在涡旋压缩机中应用蒸气喷射技术带来的潜在优势。蒸气喷射将压缩过程划分为两个阶段，减小压缩机功耗和降低蒸发器吸气流量，从而提高其容量。另外比较了两套均采用涡旋压缩机并且同为三冷吨容量的系统(一套使用蒸气喷射技术而另一套则不使用)。建立了一个多级压缩机模型，考虑了过压缩和欠压缩并根据一个单级系统得到了验证。详细的数学模拟模型预测表明，对于空调系统来说COP将提高约6～8％，而压缩机排量将降低16％。对于制冷装置来说，也能获得类似的好处。     

Free asymmetric transverse vibration of polar orthotropic annular sector plate with thickness varying parabolically in radial direction

In the present paper, free asymmetric transverse vibrations of a non-uniform polar orthotropic annular sector plate, with parabolically varying thickness in the radial direction, have been studied on the basis of classical plate theory. The circular edges of the plate are elastically restrained against translation and rotation while the straight (radial) edges are simply-supported. Fourth-order linear differential equations with variable coefficients governing the motion have been solved by using the collocation interpolation technique with Chebyshev points as the interpolating nodes. Frequency parameters of the plate with flexible boundary conditions at the circular edges for some typical values of the taper parameters, the rigidity ratios and the radii ratio have been presented.