Electrical characteristics of large scale integration (LSI) MOSFETs at very high temperatures part II: Experiment

An experimental investigation of the effects of high temperature (25°C to 300°C) on N and P channel MOS transistors is reported. At the device level, the temperature dependences of the electrical parameters are characterized individually; they include the threshold voltage, the channel mobility, and junction leakage currents. Drain current I–V characteristics are obtained for each of the subthreshold, nonsaturation, and saturation regions of operation, with temperature as a parameter. Zero-Temperature-Coefficient (ZTC) points' properties are found to be in good agreement with the theory.     

Nonlinear control with end-point acceleration feedback for a two-link flexible manipulator: Experimental results

Experimental results for end-point positioning of multi-link flexible manipulators through end-point acceleration feedback are presented in this article. The advocated controllers are implemented on a two-link flexible arm developed at the Control/Robotics Research Laboratory at Polytechnic University. The advocated approach in this article is based on a two-stage control design. The first stage is a nonlinear (1) feedback linearizing controller corresponding to the rigid body motion of the manipulator. Because this scheme does not utilize any feedback from the end-point motion, significant vibrations are induced at the end effector. To this effect, and to enhance the robustness of the closed-loop dynamics to parameter variations, the inner loop is augmented with an outer loop based on a linear output LQR design that utilizes an end-point acceleration feedback. The forearm of the manipulator is significantly more flexible as compared with the upper arm. Experimental and simulation results validate the fact that the end-effector performance is significantly better with the proposed (1) feedback linearizing control as compared with the linear independent joint PD control. In addition, the nonlinear control offers other advantages in terms of smaller and smoother actuator torques and reducing the effects of nonlinearities. Close conformation between simulation and experimental results validates the accuracy of the model.     

Electrical impedance tomography of complex conductivitydistributions with noncircular boundary

Electrical impedance tomography (EIT) uses low-frequency current and voltage measurements made on the boundary of a body to compute the conductivity distribution within the body. Since the permittivity distribution inside the body also contributes significantly to the measured voltages, the present reconstruction algorithm images complex conductivity distributions. A finite element model (FEM) is used to solve the forward problem, using a 6017-node mesh for a piecewise-linear potential distribution. The finite element solution using this mesh is compared with the analytical solution for a homogeneous field and a maximum error of 0.05% is observed in the voltage distribution. The boundary element method (BEM) is also used to generate the voltage data for inhomogeneous conductivity distributions inside regions with noncircular boundaries. An iterative reconstruction algorithm is described for approximating both the conductivity and permittivity distributions from this data. The results for an off-centered inhomogeneity showed a 35% improvement in contrast from that seen with only one iteration, for both the conductivity and the permittivity values. It is also shown that a significant improvement in images results from accurately modeling a noncircular boundary. Both static and difference images are distorted by assuming a circular boundary and the amount of distortion increases significantly as the boundary shape becomes more elliptical. For a homogeneous field in an elliptical body with axis ratio of 0.73, an image reconstructed assuming the boundary to be circular has an artifact at the center of the image with an error of 20%. This error increased to 37% when the axis ratio was 0.64. A reconstruction algorithm which used a mesh with the same axis ratio as the elliptical boundary reduced the error in the conductivity values to within 0.5% of the actual values     

A new generalized computational framework for finding objectorientation using perspective trihedral angle constraint

This paper investigates a fundamental problem of determining the position and orientation of a three-dimensional (3-D) object using a single perspective image view. The technique is focused on the interpretation of trihedral angle constraint information. A new closed form solution based on Kanatani's formulation is proposed. The main distinguishing feature of the authors' method over the original Kanatani formulation is that their approach gives an effective closed form solution for a general trihedral angle constraint. The method also provides a general analytic technique for dealing with a class of problem of shape from inverse perspective projection by using “angle to angle correspondence information.” A detailed implementation of the authors' technique is presented. Different trihedral angle configurations were generated using synthetic data for testing the authors' approach of finding object orientation by angle to angle constraint. The authors performed simulation experiments by adding some noise to the synthetic data for evaluating the effectiveness of their method in a real situation. It has been found that the authors' method worked effectively in a noisy environment which confirms that the method is robust in practical application     

A silicon carbide LOCOS process using enhanced thermal oxidation by argon implantation

A process is described for creating local oxidation of silicon structure (LOCOS) structures in silicon carbide using enhanced thermal oxidation by argon implantation. Thicker oxides were created in selective regions by using multiple energy argon implants at a dose of 1 × 10¹⁵ cm⁻² prior to thermal oxidation. Atomic force microscopy was used to analyze the fabricated LOCOS structure.     

Development of a feature recognition module for tapered and curved base features

This paper presents a feature recognition module which uses the B-rep details extracted from the STandard for Exchange of Product (STEP) format to recognize the manufacturing features on a prismatic part. It adopts the syntactic pattern recognition technique to recognize five classes of features considered in this research by matching the standard pattern strings developed for every class of feature. Using these strings, initially, the types of faces on the prismatic part are determined and edge loops are constructed. The edge loops describe a feature by the information implicit in the details of the edges, vertices, coordinate points, and directions. Using the edge loops and by checking the presence of similar edge loops on parallel faces and the connectivity of faces between parallel edge loops, the final shape of a feature is identified. The developed methodology identifies interacting, tapering, interacting–tapering, curved base features, and tapering cross-sections. Methodologies are presented here to calculate the full dimensional details of all of the features. A case study dealing with complex geometries is presented in the validation of the proposed feature recognizer.     

Synthesis,characterization, and blood compatibility of copolymers of polyamidoamines and n‐vinylpyrrolidone

Two new polyamidoamines derived from piperazine (Pip)/cyclohexylamine (CHA) and N,N′‐methylene bisacrylamide (MBA) were synthesized and subsequently copolymerized with N‐vinylpyrrolidone (NVP) under suitable reaction conditions to yield the respective copolymers (Pip–MBA–NVP and CHA–MBA–NVP). The synthesized materials were characterized by spectroscopic techniques. The material surface characteristics were checked by contact angle measurement, and the data established the relative hydrophilic characteristics of the synthesized copolymers with respect to the control poly(N‐vinylpyrrolidone). A thrombus‐formation study indicated less (<1.2 mg) clot formation on the heparinized material surfaces within a 30‐min contact time with the acid citrate dextrose human blood. The percentage of hemolysis of the blood by the materials was also less than 5%. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4068–4074, 2003