An efficient BEM formulation for three-dimensional steady-state heat conduction analysis of composites

In this work, an efficient boundary element formulation has been presented for three-dimensional steady-state heat conduction analysis of fiber reinforced composites. The cylindrical shaped fibers in the three-dimensional composite matrix are represented by a system of curvilinear line elements with a prescribed diameter which facilitates efficient analysis and modeling together with the reduction in dimensionality of the problem. The variations in the temperature and flux fields in the circumferential direction of the fiber are represented in terms of a trigonometric shape function together with a linear or quadratic variation in the longitudinal direction. The resulting integrals are then treated semi-analytically which reduces the computational task significantly. The computational effort is further minimized by analytically substituting the fiber equations into the boundary integral equation of the material matrix with hole, resulting in a modified boundary integral equation of the composite matrix. An efficient assembly process of the resulting system equations is demonstrated together with several numerical examples to validate the proposed formulation. An example of application is also included.     

Rotating ring-disc electrode (RRDE) investigation of borohydride electro-oxidation

Rotating ring-disc electrode (RRDE) voltammetry is applied for the in situ determination of hydroxy borohydride (BH₃(OH)⁻) formation during borohydride (BH₄⁻) electro-oxidation on a gold (Au) electrode in 6.0 M NaOH solution. The BH₃(OH)⁻ is detected at the ring electrode due to its further oxidation to BH₂(OH)₂⁻ by maintaining its potential in the range of −0.800 to −0.600 V vs. normal hydrogen electrode (NHE) while oxidizing BH₄⁻ on the disc electrode. The study reveals that the generation of BH₃(OH)⁻ increases if the anodic polarization of the disc electrode is increased. The RRDE ring-shielding experiments show that the electro-oxidation of BH₄⁻ occurs over a wide potential range of −0.500 to 0.400 V on the Au electrode under hydrodynamic conditions. Chronoamperometry is also used to study the BH₃(OH)⁻ oxidation in the potential range of −0.800 to −0.600 V with 0.33 M NaBH₄ in three different buffer solutions of pH 10.2, 11.0 and 11.70, respectively. The chronoamperometric studies indicate that the formation and stability of BH₃(OH)⁻ depends on the pH value.     

Modeling the drain current and its equation parameters for lightly doped symmetrical double-gate MOSFETs

A 2D model for the potential distribution in silicon film is derived for a symmetrical double gate MOSFET in weak inversion. This 2D potential distribution model is used to analytically derive an expression for the subthreshold slope and threshold voltage. A drain current model for lightly doped symmetrical DG MOSFETs is then presented by considering weak and strong inversion regions including short channel effects, series source to drain resistance and channel length modulation parameters. These derived models are compared with the simulation results of the SILVACO (Atlas) tool for different channel lengths and silicon film thicknesses. Lastly, the effect of the fixed oxide charge on the drain current model has been studied through simulation. It is observed that the obtained analytical models of symmetrical double gate MOSFETs are in good agreement with the simulated results for a channel length to silicon film thickness ratio greater than or equal to 2.     

Alternate Testing of RF Transceivers Using Optimized Test Stimulus for Accurate Prediction of System Specifications

In the recent past, with the emergence of System-on-Chip (SoC), focus has shifted towards testing system specifications rather than device or module specifications. While the problem of test accessibility for test stimulus application and response capture for such high-speed systems remains a challenge to the test engineers, new test strategies are needed which can address the problem in a practical manner. In this paper, the problem of testing the transmitter and the receiver subsystems of a RF transceiver for system level specification is addressed. Instead of using different conventional test stimuli for testing each of the system level specifications of RF subsystems, a specially crafted test stimulus is used for testing all the specifications from the response of the subsystem-under-test. A new simulation approach has also been developed to perform fast behavioral simulations in frequency domain for the system-under-test. In the test method, frequency domain test response spectra are captured and non-linear regression models are constructed to map the spectral measurements onto the specifications of interest. In the presented simulation results, the test stimuli have been validated using netlist level simulation of the subsystem-under-test and specifications have been predicted within an error of ±3% of the actual value.Soumendu Bhattacharya was born in Calcutta, India, in 1978. He received his Bachelors degree from Indian Institute of Technology, Kharagpur, India, in 2000. In 2002, he received the M.S.E.E. degree in electrical engineering from Georgia Institute of Technology, Atlanta, USA. He is currently working toward his Ph.D. degree. In the summer of 2001, he worked as a summer intern in National Semiconductor, Santa Clara, CA, USA. His research interests are in the area of test generation for mixed-signal and RF circuits and systems and design-for-test.Achintya Halder received the B.S. degree in electronics and electrical communication engineering from the Indian Institute of Technology, Kharagpur, in 1998. He worked as an IC design engineer with Texas Instruments until 2000. Currently, he is a Ph.D. student and a research assistant with the School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta. His research area is analog/RF and mixed signal testing.Ganesh P. Srinivasan received the B.E. degree in Electronics and Communication Engineering from the National Institute of Technology and Science, University of Madras, Chennai (Madras), India, in 2002. He received the M.S. degree in Electrical and Computer engineering from the Georgia Institute of Technology, Atlanta, GA, in 2004 and is currently pursuing his Ph.D. degree in Electrical and Computer Engineering at the Georgia Institute of Technology, Atlanta, GA. His research interests include low cost testing approaches for analog/RF and mixed-signal circuits, and improving performance of low cost testers for enabling high quality tests.Abhijit Chatterjee received the Bachelor of Technology degree in electrical engineering from the Indian Institute of Technology, Kanpur, India, in 1981, the M.S. degree in electrical engineering and computer science from University of Illinois at Chicago in 1983 and the Ph.D. degree in electrical and computer engineering from the University of Illinois at Urbana-Champaign in 1990. Until December 1992, he was a Research Staff Member at the General Electric Research and Development Center in Schenectady, NY. His work has been cited by the Wall Street Journal and presented on a Japanese network TV program called High Tech Shower International. He is a collaborating partner in NASAs New Millennium Project. Dr. Abhijit Chatterjee is also the author of one U.S. patent and has over one hundred publications in referenced journals and conferences.     

在双镶嵌铜互联中O.13微米器件生成用的基于PVD和ALD阻挡层的先进技术

1. Introduction The requirement of minimal bottom coverageand thick sidewall coverage for PVD-based films forlow via resistance and improved stress migration isnot easy to achieve with traditional depositionmethods. Modern I-PVD techniques give high bot-tom coverage, due to the ionized component of thedeposition flux. Sidewall coverage tends to be low,which is mainly due to off-normal deposition fluxand a less than unity sticking coefficient.     

Electrical properties of Ta/sub 2/O/sub 5/ gate dielectric on strained-Si

High dielectric constant (high-k) thin Ta/sub 2/O/sub 5/ films have been deposited on tensilely strained silicon (strained-Si) layers using a microwave plasma enhanced chemical vapour deposition technique at a low temperature. The deposited Ta/sub 2/O/sub 5/ films show good electrical properties as gate dielectrics and are suitable for microelectronic applications. The feasibility of integration of strained-Si and high-k dielectrics has been demonstrated.     

ATM cell encryption and key update synchronization

This paper presents a data compaction/randomization based approach as a mode of block encryption for ATM (Asynchronous Transfer Mode) cells. The presented approach converts a plaintext into pseudo‐random plaintext before ciphering to conceal patterns in the plaintext. The underlying idea behind this scheme is the Shannon's principles of “confusion” and “diffusion” which involve breaking dependencies and introducing as much randomness as possible into the ciphertext. In this scheme, confusion and diffusion are introduced into the system by first compressing the ATM cell payload and then spreading a continuously changing random data over the entire content of the cell. As a mode of operation for block ciphering, this scheme offers the following attractive features:(i) plaintext patterns are pseudo‐randomized and chained with ciphertext (thereby, preventing against “dictionary”, “known plaintext”, and “statistical analysis” attacks), (ii) it is self‐synchronizing, (iii) cell loss has no additional negative effect, (iv) no IV (Initialization Vector) storage is required, (v) it is encryption‐algorithm independent, (vi) there is no cell‐to‐cell dependency (no feedback from previous cells), and (vii) it is highly scalable (i.e., cells from the same stream can be ciphered and deciphered in parallel). This paper also presents a secure mechanism for in‐band synchronization of encryption/decryption key updates using a “marker‐cell” that is carried within the data channel. An important aspect of both the above mechanisms is that they do not require any changes to the ATM cell header or ATM infrastructure. This revised version was published online in June 2006 with corrections to the Cover Date.     

Minimization in variations of different parameters in different φ planes of a small-size concentric ring array antenna using firefly algorithm

The radiation pattern of a small-size concentric ring array antenna does not remain φ-symmetric, if the array is made with an appreciably lesser number of antenna elements. The sidelobe level, first null beamwidth (FNBW), half-power beamwidth (HPBW), and the null depths of the radiation pattern change significantly in different φ planes. An efficient pattern synthesis method has been developed in this work to reduce the variation of sidelobe level, FNBW, and HPBW of a small-size concentric ring array of isotropic antennas, for different φ cuts. It is done by finding out an optimum set of amplitude distribution of the array elements using firefly algorithm. The sidelobe level and the first null depth of the array are kept below a desired value for all the defined φ cuts. The directivity of the optimized array and the uniform array has been computed. The variation of all these parameters for different φ cuts has been compared to the same array with uniform excitation among the elements.     

An automated patient monitoring using discrete‐time wireless sensor networks

In recent years, Internet of Things (IoT) devices are used for remote health monitoring. For remotely monitoring a patient, only the health information at different time points are not sufficient; predicted values of biomarkers (for some future time points) are also important. In this article, we propose a powerful statistical model for an efficient dynamic patient monitoring using wireless sensor nodes through Bayesian Learning (BL). We consider the setting where a set of correlated biomarkers are measured from a patient through wireless sensors, but the sensors only report the ordinal outcomes (say, good, fair, high, or very high) to the sink based on some prefixed thresholds. The challenge is to use the ordinal outcomes for monitoring and predicting the health status of the patient under consideration. We propose a linear mixed model where interbiomarker correlations and intrabiomarker dependence are modeled simultaneously. The estimated and the predicted values of the biomarkers are transferred over the internet so that health care providers and the family members of the patient can remotely monitor the patient. Extensive simulation studies are performed to assess practical usefulness of our proposed joint model, and the performance of the proposed joint model is compared to that of some other traditional models used in the literature.