Fast detection of venous air embolism in Doppler heart sound usingthe wavelet transform

The introduction of air bubbles into the systemic circulation can result in significant morbidity. Real-time monitoring of continuous heart sound in patients detected by precordial Doppler ultrasound is, thus, vital for early detection of venous air embolism (VAE) during surgery. In this study, the multiscale feature of wavelet transforms (WT's) is exploited to examine the embolic Doppler heart sound (DHS) during intravenous air injections in dogs. As both humans and dogs share similar physiological conditions, the authors' methods and results for dogs are expected to be applicable to humans. The WT of DHS at scale 2 ^j(j=1,2) selectively magnified the power of embolic, but not the normal, heart sound. Statistically, the enhanced embolic power was found to be sensitive (P<0.01 at 0.01 ml of injected air) and correlated significantly (P<0.0005, τ=0.83) with the volume of injected air from 0.01 to 0.10 ml. A fast detection algorithm of O(N) complexity with unit complexity constant for VAE was developed (processing speed=8 ms per heartbeat), which confirmed the feasibility of real-time processing for both humans and dogs     

Influence of AIN protective film thickness on the hardness and electrophotographic properties of organic photoconductors

The deposition of a protective film to increase the hardness of an organic photoconductor (OPC) surface is an effective method to lengthen the lifetime of the OPC. In this work, A1N protective films were deposited onto OPC samples by rf reactive magnetron sputtering with low substrate temperature. The A1N films were deposited with optimized sputtering conditions and exhibited very high transmissivity in the visible wavelength range 300-800 nm. The films caused a remarkable increase in the hardness of the OPC surface, by between 32 and 62%. The acceptance voltage, dark decay rate, photodischarge rate, difference between the residual potential and the acceptance voltage of the OPC protected by A1N film were improved. These results show A1N is a suitable protective film for OPC.     

改善经编复合灯箱布横向模量的研究

分析了导致经编复合灯箱布的衬纬纱屈曲的原因,通过改变骨架织物结构和与ＰＶＣ热粘合过程提高灯箱布的横向模量,从而改善国产灯箱布的使用质量。     

Adaptive filtering of evoked potentials with radial-basis-function neural network prefilter

Evoked potentials (EPs) are time-varying signals typically buried in relatively large background noise. To extract the EP more effectively from noise, we had previously developed an approach using an adaptive signal enhancer (ASE) (Chen et al., 1995). ASE requires a proper reference input signal for its optimal performance. Ensemble- and moving window-averages were formerly used with good results. In this paper, we present a new method to provide even more effective reference inputs for the ASE. Specifically, a Gaussian radial basis function neural network (RBFNN) was used to preprocess raw EP signals before serving as the reference input. Since the RBFNN has built-in nonlinear activation functions that enable it to closely fit any function mapping, the output of RBFNN can effectively track the signal variations of EP. Results confirmed the superior performance of ASE with RBFNN over the previous method.     

Application of the hybrid Hopkins–Abbe method in full-chip OPC

The hybrid Hopkins–Abbe method is presented and shown to resolve the problem of the traditional Hopkins theory, namely the requirement for constant mask diffraction efficiencies. Simulation of electromagnetic scattering from the mask that takes into account the oblique angles of incidence from the illumination is performed by application of the domain decomposition method that is extended for offaxis illumination. Examples of 45 nm and 32 nm lines and spaces through pitch and through focus are presented to demonstrate the validity and accuracy of the hybrid Hopkins–Abbe method. The results obtained are in excellent agreement with a rigorous and independent (third party) simulator.     

Study of the breakdown failure mechanisms for power AlGaN/GaN HEMTs implemented using a RF compatible process

The breakdown failure mechanisms for a family of power AlGaN/GaN HEMTs were studied. These devices were fabricated using a commercially available MMIC/RF technology with a semi-insulating SiC substrate. After a 10 min thermal annealing at 425 K, the transistors were subjected to temperature dependent electrical characteristics measurement. Breakdown degradation with a negative temperature coefficient of ?0.113 V/K for the devices without field plate was found. The breakdown voltage is also found to be a decreasing function of the gate length. Gate current increases simultaneously with the drain current during the drain-voltage stress test. This suggests that the probability of a direct leakage current path from gate to the 2-DEG region. The leakage current is attributed by a combination of native and generated traps/defects dominated gate tunneling, and hot electrons injected from the gate to channel. Devices with field plate show an improvement in breakdown voltage from ～40 V (with no field plate) to 138 V and with lower negative temperature coefficient. A temperature coefficient of ?0.065 V/K was observed for devices with a field plate length of 1.6 μm.     

Health and wellness monitoring through wearable and ambient sensors: exemplars from home-based care of elderly with mild dementia

Monitoring and timely intervention are extremely important in the continuous management of health and wellness among all segments of the population, but particularly among those with mild dementia. In relation to this, we prescribe three design principles for the construction of services and applications. These are ambient intelligence, service continuity, and micro-context. In this paper, we provide three exemplars from our research and development activities that illustrate the use of these design principles in the construction of services and applications. All the applications are drawn from the field of care for mild dementia patients in their living quarters.     

AC-Boosting Frequency Compensation with Double Pole-Zero Cancellation for Multistage Amplifiers

In this paper, we present an AC-boosting compensation topology with double pole-zero cancellation (ACBC-DPZ) for a multistage amplifier driving a very large capacitive load. The proposed technique modifies the original AC-boosting compensation (ACBC) topology to increase the power-bandwidth efficiency and reduce the size for the output power transistor and compensation capacitor. Simulation results show that the ACBC-DPZ amplifier using a CSM 0.18 μm CMOS process can achieve a unity gain bandwidth of 14 MHz and an average slew rate of 3.88 V/μs at 1500 pF load. The amplifier dissipates 2.55 mW at a 1.8 V supply.     

Temperature profile effects in accelerated thermal cycling of SnPb and Pb-free solder joints

Accelerated thermal cycling (ATC) has been widely used in the microelectronics industry for reliability assessment. ATC testing decreases life cycle test time by one or more of the following means: increasing the heating and cooling rate, decreasing the hold time, or increasing the range of the applied temperature. The relative effect of each of these cycle parameters and the failure mechanisms they induce has been the subject of many studies; however uncertainty remains, particularly regarding the role of the heating and cooling rate. In this research, three conditions with two ramp rates (14 °C/min and 95 °C/min) and two temperature ranges (ΔT = 0–100 °C and −40 to 125 °C) were applied to resistor 2512 and PBGA 256 test vehicles assembled with SnPb and Pb-free solders. The test results showed that the higher ramp rate reduced the testing time while retaining the same failure modes, and that the damage per cycle increased with the temperature difference. For the resistors, the Pb-free solder joints lasted longer than the SnPb joints at the smaller ΔT, but were inferior at the larger ΔT. In contrast, the Pb-free solder joints in the PBGA test vehicles lasted longer than the SnPb solder under both conditions.     

Optimization of photomask design for reducing aberration-induced placement error

In semiconductor manufacturing, the accurate placement of circuit components ensures the proper functioning of microelectronic circuits. This is often subject to photolithography, an optical technique that transfers circuit patterns from photomasks to silicon wafers. Sources of placement error include aberration and misalignment between different levels, and we focus on the former. Aberration is an optical phenomenon that often degrades imaging system performance. Since aberration differs from one imaging system to another, a photomask design that minimizes the aberration-induced placement error is desired. In this paper, we discuss the optimization process of a general one-dimensional mask pattern under a general illumination condition. The constraint is a known population mean of the root mean square aberrations for the imaging systems under consideration. To apply the theory, we search for the optimal parameters for two common mask designs: alternating phase-shifting masks (PSMs) and attenuated PSMs. The theoretical results are compared with those from a Monte Carlo analysis on a large set of imaging systems. These results are indicative to mask manufacturers and circuit designers of increasing manufacturability of circuits.