In situ imaging of multiphase bio-interfaces at the micro-/nanoscale

The multiphase bio-interfacial system constituted by biological surfaces and their surrounding environment is usually considered to be an essential clue for exploring the mysterious relationship between surface architecture and function. As a visualizing method to understand these systems, in situ imaging of multiphase interfaces (e.g., air/liquid/solid and oil/water/solid systems) at the micro-/nanoscale, still remains a huge challenge, as a result of their heterogeneity and complexity. Here, recent progress on real-space micro-/nanoscale imaging of multiphase bio-interfacial systems is reviewed; this includes several techniques and imaging results on bio-interfaces, such as the lotus leaf, fish scale, living cell's surface, and fresh tissue surface. The results evidently show that interfacial structures have a significant impact on the state of the microscopic multiphase interface, further influencing specific functions. Based on this research, technical innovations, some more complicated multiphase interface systems, and structure-function coupling mechanism are proposed.     

Generalized Analysis of Phase-Sensitive Detection-Circuit Operating Characteristics at the Signal Detection in the Presence of Noise

A new generalized analysis is presented of operating characteristics of phase-sensitive detector circuits, assuming that the input signal and the reference wave are in the presence of independent, stationary, and additive Gaussian noise. The generalized criteria are determined for the detector optimum operating conditions and for minimization of the detector characteristic essential nonlinearities by means of computer-aided analysis, using high-density discrete value calculations. The results of the analysis are given in normalized form and can be directly applied to evaluate in detail the detector-circuit performance and characteristic essential nonlinearities over a wide dynamic range of operating conditions. Furthermore, particular emphasis is laid on the determination of optimum detector-circuit operating conditions in contemporary instrumentation systems.     

卷积编码DS/CDMA系统中的迭代多用户接收器

提出了一种用于卷积编码DS/CDMA系统的迭代多用户接收器。该接收器由一个软输入/软输出（SISO）的判决反馈多用户检测器和一组单用户SISO信道译码器组成，每次迭代过程中，多用户检测器和信道译码器都输出外信息作为下一次迭代的光验信息，仿真结果表明，这种接收器能使远近效应影响下弱用户的比特误码性能接受单用户限。     

Optoelectronic region of interest detection: an application in automated cytology

Diagnostic cytology, which is used to screen for cervical cancer, involves characterizing cellular features such as shape, size, and texture. Automated screening of cervical smear slides is desirable but computationally challenging since each slide requires processing 2 x 10(9) pixels at a resolution of 0.8 mum per pixel. We demonstrate that the throughput of optical processors can be exploited in automated cervical smear-screening systems. In particular, we identify a morphological shape detector to perform the initial region of interest (ROI) detection and to demonstrate experimentally its optoelectronic implementation. The ROI detector is tested on 200 images, and its performance is characterized as a receiver operating characteristic (ROC). The area under the ROC curve is as high as 96.4% of the total area. The simulation and the experimental results are found comparable, and the discrepancy between the two results is determined to be a function of the number of bits represented in the filter plane device.     

Extraordinary Thermoelectric Performance Realized in n‐Type PbTe through Multiphase Nanostructure Engineering

Lead telluride has long been realized as an ideal p‐type thermoelectric material at an intermediate temperature range; however, its commercial applications are largely restricted by its n‐type counterpart that exhibits relatively inferior thermoelectric performance. This major limitation is largely solved here, where it is reported that a record‐high ZT value of ≈1.83 can be achieved at 773 K in n‐type PbTe‐4%InSb composites. This significant enhancement in thermoelectric performance is attributed to the incorporation of InSb into the PbTe matrix resulting in multiphase nanostructures that can simultaneously modulate the electrical and thermal transport. On one hand, the multiphase energy barriers between nanophases and matrix can boost the power factor in the entire temperature range via significant enhancement of the Seebeck coefficient and moderately reducing the carrier mobility. On the other hand, the strengthened interface scattering at the intensive phase boundaries yields an extremely low lattice thermal conductivity. This strategy of constructing multiphase nanostructures can also be highly applicable in enhancing the performance of other state‐of‐the‐art thermoelectric systems.     

An analytical method for the calculation of static characteristicsof linear step motors for control rod drives in nuclear reactors

An analytical method for calculating static characteristics of linear dc step motors (LSM) is described. These multiphase passive-armature motors are now being developed for control rod drives (CRD) in large nuclear reactors. The static characteristics of such LSM is defined by the variation of electromagnetic force with armature displacement and it determines motor performance in its standing and dynamic modes of operation. The proposed analytical technique for calculating this characteristic is based on the permeance analysis method applied to phase magnetic circuits of LSM. Reluctances of various parts of phase magnetic circuit is calculated analytically by assuming probable flux paths and by taking into account complex nature of magnetic field distribution in it. For given armature positions stator and armature iron saturations are taken into account by an efficient iterative algorithm which gives fast convergence. The method is validated by comparing theoretical results with experimental ones which shows satisfactory agreement for small stator currents and weak iron saturation     

An instantaneous amplitude detector for variable frequencythree-phase sinusoidal signals

A fast peak detector for three-phase variable frequency sinusoidal signals is proposed. This new detector fully uses the three-phase characteristic to achieve instantaneous response, frequency and phase sequence independence characteristics. Also, the proposed detector possesses excellent linearity and low sensitivity to phase unbalance and harmonic distortion. Theoretical basis, hardware implementation, and experimental results are all detailed in this context     

Hybrid detectors for wireless orthogonal frequency division multiplexing with code division multiplexing systems based on reliability information

Orthogonal frequency division multiplexing with code division multiplexing (OFDM-CDM) is attractive for the next generation high-speed wireless systems due to the fact that the performance of OFDM-CDM systems can be considerably improved by employing a joint detection scheme such as the maximum likelihood (ML) detector. However, the complexity of the ML detector increases rapidly as the number of orthogonal spreading codes and/or the number of bits per modulation symbol increase. In this study, the authors introduce a unified detection model and propose two hybrid detectors, which combine zero forcing (ZF) with successive interference cancellation (SIC) and sphere detection (SD) algorithms, respectively. After obtaining the initial solution from the front-end ZF receiver, the proposed back-end algorithms are adopted to extend the potential solution list and search for the final result. The objective is to utilise the combination of a simplified linear equaliser and a comprehensive detection scheme to achieve enhanced performance and offer alternatives to the more complex and channel-estimation-sensitive minimum mean squared error (MMSE) scheme. The results show that the proposed hybrid detectors are able to achieve superior performance compared to the MMSE scheme and provides a significant performance improvement compared to the conventional OFDM counterpart.     

Shack-Hartmann sensor improvement using optical binning

We present a design improvement for a recently proposed type of Shack-Hartmann wavefront sensor that uses a cylindrical (lenticular) lenslet array. The improved sensor design uses optical binning and requires significantly fewer detector pixels than the corresponding conventional or cylindrical Shack-Hartmann sensor, and so detector readout noise causes less signal degradation. Additionally, detector readout time is significantly reduced, which reduces the latency for closed loop systems and data processing requirements. We provide simple analytical noise considerations and Monte Carlo simulations, we show that the optically binned Shack-Hartmann sensor can offer better performance than the conventional counterpart in most practical situations, and our design is particularly suited for use with astronomical adaptive optics systems.     

Asymmetric Air Cathode Design for Enhanced Interfacial Electrocatalytic Reactions in High-Performance Zinc–Air Batteries

The rechargeable zinc–air battery (ZAB) is a promising energy storage technology owing to its high energy density and safe aqueous electrolyte, but there is a significant performance bottleneck. Generally, cathode reactions only occur at multiphase interfaces, where the electrocatalytic active sites can participate in redox reactions effectively. In the conventional air cathode, the 2D multiphase interface on the surface of the gas diffusion layer (GDL) inevitably results in an insufficient amount of active sites and poor interfacial contact, leading to sluggish reaction kinetics. To address this problem, a 3D multiphase interface strategy is proposed to extend the reactive interface into the interior of the GDL. Based on this concept, an asymmetric air cathode is designed to increase the accessible active sites, accelerate mass transfer, and generate a dynamically stabilized reactive interface. With a NiFe layered-double-hydroxide electrocatalyst, ZABs based on the asymmetric cathode deliver a small charge/discharge voltage gap (0.81 V at 5.0 mA cm⁻²), a high power density, and a stable cyclability (over 2000 cycles). This 3D reactive interface strategy provides a feasible method for enhancing the air cathode kinetics and further enlightens electrode designs for energy devices involving multiphase electrochemical reactions.     

Iterative reduced-state decoding for coded partial-response channels

The conventional iterative decoding based on the Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm rises exponentially in terms of channel memory length. In this paper, we propose a low-complexity soft-input/soft-output (SISO) channel detector based on tentative hard estimates fed back from the outer decoder in the previous iteration. The computational complexity of the proposed detector is polynomial in terms of the channel memory length. To demonstrate the performance/complexity tradeoff of the proposed detector, we present simulation results for 9-tap, 11-tap, and 12-tap channels. We show that the proposed detector significantly reduces the computational complexity with only slight performance degradation compared to the full-complexity BCJR algorithm.     

Predictive-space vector PWM current control method for asymmetrical dual three-phase induction motor drives

The interest in multiphase drives has re-emerged in the last decade, being the asymmetrical dual threephase induction motor drive one of the most popular options. Predictive control techniques, already implemented in three-phase drives, have been recently adapted to the multiphase case. Schemes proposed so far have demonstrated high performance at the expenses of a higher degree of computational cost and illdefined switching frequency. In this study, a predictive space vector PWM (SVPWM) current control technique with fixed switching frequency is proposed for asymmetrical dual three-phase AC drives. Fast torque and current response are achieved similar to those obtained using conventional predictive current control techniques. Electrical noise suppression is favoured as in PWM current control methods. Experimental results are provided to examine the benefits of the proposed control method.     

多基地声纳系统检测性能分析

分析了多基地声纳系统的检测性能。利用检测统计量,推导了在背景噪声为高斯白噪声、信号为高斯随机过程的情况下,主动多基地声纳系统的最优检测接收机。指出主动多基地声纳系统的最优检测接收机为匹配滤波器。然后,提出了一种基于＂和检测＂原理的简化检测接收机,并分析了它的检测性能及基地选择原则。结果表明：对于这种简化的检测接收机,当一个基地的检测性能远远优于其它基地时,如果再将其它基地融入到处理系统中,系统的检测性能不会得到明显提高,甚至可能会下降;另一方面,当各个基地的输入信噪比接近时,参与检测的基地个数越多,系统的检测性能越好。     

高阶谱双通道的水声信号检测方法研究

实际海洋环境中,水下声纳系统往往因环境条件的失配而性能下降。从高阶统计量分析的角度来研究失配条件下的水声信号检测问题。采用二阶、三阶统计联合分析的方法,把双谱能量检测器与常规能量检测器联合构成一种双谱双通道检测器。它同时利用了水声信号中的二阶和三阶统计信息,增加了所利用的信息量,且能在更大程度上适应复杂水声环境变化的要求,改善和提高了水声信号的检测性能。计算机仿真证明了上述算法的有效性。该方法为失配条件下的水下微弱信号检测提供了一条可能的途径。     

ON THE COMPUTATION OF MULTIPHASE EQUILIBRIA

The main purpose of this paper is to present a new mathematical programming formulation of the multiphase equilibrium problem along with a Newton-type algorithm for its solution. The approach pursued relies on the Gibbs free energy function and geometric programming duality. The problem arised in connection with a real-life problem in oil reservoir engineering. The presentation of the model is based on a detailed mathematical analysis of the multiphase equilibrium problem. The computational results reported are obtained using data systems from oil reservoir engineering.     

Measure of the influence of detector noise on temperature-measurement accuracy for multiband infrared systems

The noise-equivalent temperature difference is a measure of the detector-noise-limited sensitivity of single-band IR systems for noncontact temperature measurement. However, because its definition is based on the signal-to-noise ratio in a single detector channel, the notion of noise-equivalent temperature difference must be generalized in case of dual-band or multiband IR systems. A new measure of temperature-measurement sensitivity is proposed that can be used to describe single-band, dual-band, and multiband IR measurement systems. With this measure a comparison of temperature-measurement accuracy among single-band, dual-band, and multiband systems was carried out.     

Noise-Enhanced Detection of Subthreshold Signals With Carbon Nanotubes

Electrical noise can help pulse-train signal detection at the nanolevel. Experiments on a single-walled carbon nanotube transistor confirmed that a threshold exhibited stochastic resonance (SR) for finite-variance and infinite-variance noise: small amounts of noise enhanced the nanotube detector's performance. The experiments used a carbon nanotube field-effect transistor to detect noisy subthreshold electrical signals. Two new SR hypothesis tests in the Appendix also confirmed the SR effect in the nanotube transistor. Three measures of detector performance showed the SR effect: Shannon's mutual information, the normalized correlation measure, and an inverted bit error rate compared the input and output discrete-time random sequences. The nanotube detector had a threshold-like input-output characteristic in its gate effect. It produced little current for subthreshold digital input voltages that fed the transistor's gate. Three types of synchronized white noise corrupted the subthreshold Bernoulli sequences that fed the detector. The Gaussian, the uniform, and the impulsive Cauchy noise combined with the random input voltage sequences to help the detector produce random output current sequences. The experiments observed the SR effect by measuring how well an output sequence matched its input sequence. Shannon's mutual information used histograms to estimate the probability densities and computed the entropies. The correlation measure was a scalar inner product of the input and output sequences. The inverted bit error rate computed how often the bits matched between the input and output sequences. The observed nanotube SR effect was robust: it persisted even when infinite-variance Cauchy noise corrupted the signal stream. Such noise-enhanced signal processing at the nanolevel promises applications to signal detection in wideband communication systems and biological and artificial neural networks     

A hybrid multiuser detector for DS-UWB systems with matched filter and error-bit recognizer

In this article, we propose a hybrid algorithm of multiuser detection (MUD) for direct sequence ultra-wideband (UWB) communication systems, based on matched filters (MF) and error-bit recognizers (ER). The ER embraces three steps: bit mapping, K-means clustering, and sign judgment. In this detector, we construct a mapping function and map the output base-band bits from MFs into a one-dimensional feature space to get the amplitude information. After that, we set an initial value and classify the bits into right bits and wrong ones by K-means clustering. Finally, we make the sign judgment to prevent some right bits being picked out as wrong bits and correct the wrong bits to reduce the bit error rate (BER) of the system. Compared to a conventional detector based on MFs and minimum mean square error detector, to a large extent, our detector can improve the BER performance of a system because of high recognition probability of the wrong bits in K-means clustering. What is more, the simulation results show that the proposed hybrid MUD is not sensitive to the number of users. It can achieve a good BER performance and low computational complexity when there are 20 UWB transmitters in the channel.     

双重磁检测器电流比较仪的开环特性研究

介绍了一种全新的直流大电流测量方法 ,这种方法是基于磁调制器和磁放大器双重磁检测器原理。文中对这种双重磁检测器的开环特性进行了理论计算和试验测试。理论计算和试验测试均表明其开环传输特性只有零安匝一个过零点 ,克服了传统磁调制器的开环传输特性曲线有若干过零点的缺陷和弊端 ,大大提高了系统闭环后的稳定性和可靠性 ,且在零安匝附近灵敏度高、线性好 ,同时具备了磁调制器和磁放大器的优点