Deposition of silicon films in presence of nitrogen plasma—A feasibility study

A design, development and validation work of plasma based ‘activated reactive evaporation (ARE) system’ is implemented for the deposition of the silicon films in presence of nitrogen plasma on substrate maintained at room temperature. This plasma based deposition system involves evaporation of pure silicon by e-beam gun in presence of nitrogen plasma, excited by inductively coupled RF source (13.56 MHz). The activated silicon reacts with the ionized nitrogen and the films get deposited on silicon substrate. Different physical and process related parameters are changed. The grown films are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and ellipsometry. The results indicate that the film contains silicon nitride and a phase of silicon oxy nitride deposited even at room temperature. This shows the feasibility of using the ARE technique for the deposition of silicon films in nitrogen plasma.     

Microstructure and electrical properties of ‘pre-sintered bismuth ruthenate-glass composite’ based thick film paste for resistor application

Thick film resistors based on a bismuth ruthenium oxide (BRO) and a leadborosilicate glass have been used to study the effect of a ‘pre-sintered glass–ceramic composite’ powder in the paste preparation on the resistor characteristics. Pre-sintered glass–ceramic composite was prepared by heating a physical admixture of leadborosilicate glass frit and BRO as functional material at various temperatures above the softening point of the glass. The microstructural changes associated with ‘pre-sintering’ step were studied using scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction, and, were correlated to the electrical characteristics of these resistors. It was observed that pre-sintering at a lower temperature of 600°C helps in restricting the agglomeration of conducting BRO particles and in generating more non-sintered contacts between them, which improves consistency in sheet resistance and hot temperature coefficient of resistance (TCR). At the same time, the pre-sintering step lowers the absolute TCR value, mostly by way of compensation of the high negative TCR of glass by the positive TCR of Pb containing ruthenate phases and/or RuO₂, which have positive TCR. It is explained that the Pb containing BRO phases are formed in situ through the Bi???Pb exchange reaction. The pre-sintering temperature of 600°C was, thus, found to be optimum for the present processing conditions.     

Transaction-Centric Reconciliation in Disconnected Client–Server Databases

As mobile computing devices become more and more common, mobile databases are becoming popular. An important feature of these database systems is their ability to allow optimistic replication of data by providing disconnected mobile devices the ability to perform local updates. The key problem to this approach is the reconciliation problem, i.e. the problem of serializing potentially conflicting updates from disconnected clients on all replicas of the database. Reconciliation of conflicting updates is especially critical for disconnected databases where disconnected updates are allowed. We examine some choices for providing solutions to the reconciliation problem. We then present an algorithm that combines multiversion concurrency control schemes on a server with reconciliation of updates from disconnected clients. We also describe a simple but illustrative sample application. Finally we present our conclusions.     

Things that go bump in the light: On the optical specification of contact severity.

Psychologists are intrigued with the idea that optical variables can specify not only the time until an object impacts an observer but also the severity of the impact. However, the mapping between the optical variables (τ and τ?) and the kinematic variables (velocity, acceleration) has been misstated, erroneously implying that there exist critical values of the optical variables used for locomotion and control. In this commentary, the mathematical relationship between the optical and kinematic variables is reexamined and the erroneous assumptions that have led to the proposal of critical values are shown. Also examined are the empirical data on deceleration to approach (particularly from active control paradigms) to assess whether the proposed optical variables are likely candidates for control strategies. Finally, problems associated with numerical approximations to dynamic systems, particularly when analytic solutions exist, are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Regional pole placement of multivariable systems under controlstructure constraints

Many controller realizations are structurally constrained. Some typical examples are static output feedback, constant gain feedback for multiple operating points of a system, two-controller feedback, and decentralized feedback. A general class of problems of regional pole placement of multivariable systems with such control structure constraints is considered and a unified numerical method is given to solve them. First a problem in this class is converted to a problem of solving a system of equalities and inequalities. This system is then solved by using a modified homotopy method     

Effect of exercise on acid-base status and ventilatory kinetics

OBJECTIVES: To study the clinical spectrum of an acute severe encephalopathy occurring in 2 patients after recovery from falciparum malaria infection and to compare it with the reported clinical features of the postmalaria neurological syndrome. DESIGN: Case report. SETTING: Tertiary care hospital. PATIENTS: Two patients presented with acute onset of fluctuating motor aphasia, severe generalized myoclonus, and postural tremor. Additional signs were cerebellar ataxia, and in 1 patient, generalized epileptic seizures. Magnetic resonance imaging of the brain revealed patchy white matter lesions in 1 patient. Clinically, the patients' conditions continued to worsen until corticosteroids were introduced, the use of which induced a rapid, albeit incomplete, recovery. CONCLUSIONS: We describe a new, severe variant of the still poorly defined postmalaria neurological syndrome. We propose a preliminary classification of this syndrome, according to its clinical characteristics, as follows: a mild or localized form, characterized by isolated cerebellar ataxia or postural tremor; a diffuse, but relatively mild encephalopathic form, characterized by acute confusion or epileptic seizures; and a severe, corticosteroid-responsive encephalopathy that is characterized by motor aphasia, generalized myoclonus, postural tremor, and cerebellar ataxia.     

Investigating the fault tolerance of neural networks

Particular levels of partial fault tolerance (PFT) in feedforward artificial neural networks of a given size can be obtained by redundancy (replicating a smaller normally trained network), by design (training specifically to increase PFT), and by a combination of the two (replicating a smaller PFT-trained network). This letter investigates the method of achieving the highest PFT per network size (total number of units and connections) for classification problems. It concludes that for non-toy problems, there exists a normally trained network of optimal size that produces the smallest fully fault-tolerant network when replicated. In addition, it shows that for particular network sizes, the best level of PFT is achieved by training a network of that size for fault tolerance. The results and discussion demonstrate how the outcome depends on the levels of saturation of the network nodes when classifying data points. With simple training tasks, where the complexity of the problem and the size of the network are well within the ability of the training method, the hidden-layer nodes operate close to their saturation points, and classification is clean. Under such circumstances, replicating the smallest normally trained correct network yields the highest PFT for any given network size. For hard training tasks (difficult classification problems or network sizes close to the minimum), normal training obtains networks that do not operate close to their saturation points, and outputs are not as close to their targets. In this case, training a larger network for fault tolerance yields better PFT than replicating a smaller, normally trained network. However, since fault-tolerant training on its own produces networks that operate closer to their linear areas than normal training, replicating normally trained networks ultimately leads to better PFT than replicating fault-tolerant networks of the same initial size.     

Estimation of the Fraction Defective in Curtailed Sampling Plans by Attributes

In this paper we have obtained the maximum likelihood estimate of the fraction defective (p) under three different sampling plans. Plan 1 considers complete inspection of the sample, Plan 2 considers curtailing of the inspection at the rejection stage and Plan 3 considers curtailing of the inspection at both the acceptance and rejection stages.