Integrated Design and Test of Mixed-Signal Circuits

In this paper, the integration of design and test flows for mixed-signal circuits is discussed. The aim is to decrease test generation and debugging costs and time-to-market for the analogue blocks in mixed-signal circuits. A tool developed in order to automate the data sharing between design and test environments is described and the functionality of this tool is explained. The generation of a test plan consists of the selection of the separate test functions and addition of commands for control signal generation and tester routing. The usage of design data for each of these functions is explained and the tool is evaluated in the design and testing of a mixed-signal demonstrator circuit. Results from this experience are discussed.     

Moving target detection using super‐resolution algorithms with an ultra wideband radar

We present subspace based detection algorithms for detecting moving targets applied to the data collected by an ultra wideband radar system. Combining the results of time reversal MUSIC algorithm and delay estimation MUSIC methods resulted in successful localization of targets. We have investigated methods to resolve the ambiguities in target detection and we performed experiments using two targets to test the effectiveness of the algorithms. © 2010 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 20, 237–244, 2010     

Investigation of the effect of solidification processing parameters on the rod spacings and variation of microhardness with the rod spacing in the Sn–Cu hypereutectic alloy

Sn–3 wt% Cu hypereutectic alloy was prepared in a graphite crucible under the vacuum atmosphere. The samples were directionally solidified upwards under argon atmosphere with different temperature gradients (G = 4.24–8.09 K/mm) at a constant growth rate (V = 7.64 μm/s) and with different growth rates (V = 2.24–133.33 μm/s) at a constant temperature gradient (G = 4.24 K/mm) by using a Bridgman type directional solidification apparatus. The microstructure of directional solidified Sn–3 wt% Cu alloy seems to be rod eutectic structure. The influence of the growth rate (V) and temperature gradient (G) on the rod spacing (λ) and undercooling (ΔT) were analysed. The values of λ²V, λ²G, ΔTλ, ΔTV^−0.5 and ΔTG^−0.5 were determined by using the Jackson–Hunt eutectic theory. The dependence of microhardness (HV) on the rod spacing (λ) was analyzed. According to present results, it has been found that the value of HV increases with the increasing the value of λ.     

A comparison of basic dye adsorption onto zeolitic materials synthesized from fly ash

This investigation reveals the adsorption characteristics of two basic dyes, thionine (TH) and safranine T (ST), onto fly ash (FA) and its three zeolitized products prepared at different hydrothermal conditions. Typical two-step isotherms were observed for TH adsorption onto four adsorbents, whereas the isotherms of the larger ST molecules were S-shaped. The adsorption capacities of the zeolitized fly ash (ZFA) estimated from the first plateau region of the TH isotherms was nearly twice the FA capacity. The capacities increased by up to five times in the second plateau region. The adsorption capacity of FA for ST is equivalent that of TH, whereas the capacities of ZFA are lower than those found for TH. The equilibrium results were well-described by the Freundlich isotherm model. The kinetic data obtained in the temperature range of 298-318 K was analyzed using Paterson's and Nernst Plank's approximations based on the homogeneous surface diffusion model (HSDM). The thermodynamic functions for the transition state were evaluated from the temperature-dependence of the surface diffusion coefficients by applying the Eyring model.     

Pregnancy in dialysis-dependent women--the importance of frequent dialysis and collaborative care: a case report

An increasing number of successful pregnancies have been reported among women on chronic hemodialysis. Even with reduced fertility and high risk of complications, women of childbearing age receiving hemodialysis, should not be discouraged from pregnancy. Practitioners should be familiar with the effects of renal disease on pregnancy, consult patients about the possibility of pregnancy and its hazards and provide, if necessary, prompt surveillance and treatment. This paper describes the case of an unplanned but successful pregnancy of a woman receiving hemodialysis, emphasizing pregnancy management, mother's response evaluation, and infant growth.     

HFE gene mutation is a risk factor for tissue iron accumulation in hemodialysis patients

Introduction: HFE gene mutations are responsible from iron overload in general population. Studies in hemodialysis patients investigated the effect of presence of HFE gene mutations on serum ferritin and transferrin saturation (TSAT) with conflicting results. However effect of HFE mutations on iron overload in hemodialysis patients was not previously extensively studied. Methods: 36 hemodialysis patients (age 51.3 ± 15.6, (18/18) male/female) and 44 healthy control subjects included in this cross sectional study. Hemoglobin, ferritin, TSAT in the preceding 2 years were recorded. Iron and erythropoietin (EPO) administered during this period were calculated. Iron accumulation in heart and liver was detected by MRI. Relationship between HFE gene mutation, hemoglobin, iron parameters and EPO doses, and tissue iron accumulation were determined. Findings: Iron overload was detected in nine (25%) patients. Hemoglobin, iron parameters, weekly EPO doses, and monthly iron doses of patients with and without iron overload were similar. There was no difference between control group and hemodialysis patients with respect to the prevalence of HFE gene mutations. Iron overload was detected in five of eight patients who had HFE gene mutations, but iron overload was present in 4 of 28 patients who had no mutations (P = 0.01). Hemoglobin, iron parameters, erythropoietin, and iron doses were similar in patients with and without gene mutations. HFE gene mutations remained the main determinant of iron overload after multivariate logistic regression analysis (P = 0.02; OR, 11.6). Discussion: Serum iron parameters were not adequate to detect iron overload and HFE gene mutation was found to be an important risk factor for iron accumulation.     

A Sigma-Delta ADC design automation tool with embedded performance estimator

A system-level design automation tool for designing discrete time, switched-capacitor, Sigma-Delta analog-to-digital converters is presented. The presented work utilizes a performance estimator based on EKV models. The design automation tool takes advantage of high level analytical single-bit and multibit models of the building blocks. With the contribution of the performance estimator module, the tool provides an extensive design environment for designing Sigma-Delta analog-to-digital converters. Developed models and their effects are presented with examples. Design examples for 0.5 and technologies are provided for proving the flexibility of the design automation tool.     

C/SiC复合材料的制备及性能研究

本文对聚碳硅烷化学转化法制备碳纤维增强碳化硅复合材料的生产工艺进行了研究,探讨了工艺参数对材料性能的影响.研究结果表明,聚碳硅烷分子量是影响材料性能的重要参数,纤维和基体间热膨胀系数的不匹配可通过向基体内加少量二氧化锆进行改善.材料的力学和热学性能测试结果表明,C/SiC复合材料具有较好的综合性能,其断裂韧性比未增强的单一陶瓷提高较多.利用电镜分析了弯曲试样的断口形貌.     

Investigation of Trap States in AlInN/AlN/GaN Heterostructures by Frequency-Dependent Admittance Analysis

We present a systematic study on the admittance characterization of surface trap states in unpassivated and SiN _x -passivated Al_0.83In_0.17N/AlN/GaN heterostructures. C–V and G/ω–V measurements were carried out in the frequency range of 1 kHz to 1 MHz, and an equivalent circuit model was used to analyze the experimental data. A detailed analysis of the frequency-dependent capacitance and conductance data was performed, assuming models in which traps are located at the metal–AlInN surface. The density (D _t) and time constant (τ _t) of the surface trap states have been determined as a function of energy separation from the conduction-band edge (E _c − E _t). The D _st and τ _st values of the surface trap states for the unpassivated samples were found to be D_st @ (4 - 13) ×10¹² D_{\rm{st}} \cong (4 - 13) \times 10^{12}  eV ^{- 1} cm ^{- 2} {\hbox{eV}}^{ - 1} {\hbox{cm}}^{ - 2} and τ _st ≈ 3 μs to 7 μs, respectively. For the passivated sample, D _st decreased to 1.5 ×10¹² 1.5 \times 10^{12}  eV ^{- 1} cm ^{- 2} {\hbox{eV}}^{ - 1} {\hbox{cm}}^{ - 2} and τ _st to 1.8 μs to 2 μs. The density of surface trap states in Al_0.83In_0.17N/AlN/GaN heterostructures decreased by approximately one order of magnitude with SiN _x passivation, indicating that the SiN _x insulator layer between the metal contact and the surface of the Al_0.83In_0.17N layer can passivate surface states.     

An in situ experimental study of grain growth in a nanocrystalline Fe91Ni8Zr1 alloy

Grain growth and microstructural evolution of thermally stabilized Fe₉₁Ni₈Zr₁ were investigated by in situ and ex situ studies. Our investigations suggest that the microstructural evolution is fairly slow and the microstructure shows stabilization up to about 700 °C. Above this temperature, a certain fraction of grains grow abnormally into the nanocrystalline matrix, resulting in a bimodal microstructure and causing the complete loss of thermal stability. The reason for abnormal grain growth and the loss of thermal stability is identified as the appearance of the fcc γ-phase and consequent reduction in the total area of grain boundaries and the overall stored energy.