Frequency tracking by MAP demodulation and by linear prediction techniques

Maximum posterior probability (MAP) demodulation with delay of an FM signal in the presence of noise is realized and compared with a) Griffiths' linear prediction method, b) a complex-valued version of Griffiths' method, c) three new modifications of Griffiths' method which can improve the performance of this method, and d) maximum-likelihood (ML) frequency estimation. These first quantitative results on MAP demodulation with delay show an advantage of a few db in output SNR at high input CNR and much larger advantages at low input CNR, relative to the other techniques.     

电化学扫描探针显微镜在表面微/纳米加工的应用

概述了在固 /液界面微 /纳米加工中经常采用的三种电化学扫描探针显微镜 (EC SPM )技术 ,分别讨论了电化学扫描隧道显微镜 (EC STM )、电化学原子力显微镜 (EC AFM )和扫描电化学显微镜 (SECM )在应用于微 /纳米加工时的基本原理和各种方法 ,并综合比较和分析了这三种技术的优缺点     

TEM characterization of Si nanowires grown by CVD on Si pre-structured by nanosphere lithography

Silicon nanowires (SiNWs) were grown on Si(1 0 0) and Si(1 1 1) substrates by chemical vapour deposition (CVD) via the vapour–liquid–solid (VLS) mechanism with small gold particles used as seeds. In order to control the diameter of nanowires, their density on the substrate and their orientation we controlled the size and the distribution of Au seed particles. This was accomplished using nanosphere lithography (NSL) by which regular arrays of Au nanoparticles can be generated. This allowed us to grow single-crystalline SiNWs perpendicular to the surface of Si(1 1 1) substrates. The SiNWs and their Au caps were studied with respect to their morphology and composition using TEM, HREM and EFTEM methods. Clusters of Au are observed along the surface of SiNWs and the existence of a thin Si film on gold particles capping the SiNWs is demonstrated.     

激光裂解钛酸酯改性聚硅氧烷制备陶瓷涂层

为了解决先驱体转化陶瓷法中金属粉末活性填料在制备陶瓷涂层中分散不均的问题,采用激光裂解钛酸四丁酯改性聚二甲基硅氧烷法在金属基体表面制备陶瓷涂层,通过电子显微镜、X射线衍射和X射线光电子能谱等手段,取得了涂层表面并分析了激光裂解钛酸四丁酯改性聚二甲基硅氧烷生成物的组成与结构。结果表明,钛酸四丁酯添加量的质量分数为0.05时,涂层表面不同区域的Ti相对含量均在3%左右,Ti元素在涂层中分布均匀,钛酸四丁酯改性聚二甲基硅氧烷在激光作用下生成的陶瓷涂层主要由晶态的SiC,TiO₂,非晶态SiO₂,（TiO₂）₅₆（SiO₂）₄₄以及C₆H₁₈OSi₂等组成,激光裂解过程中新生的TiO₂,（TiO₂）₅₆（SiO₂）₄₄等陶瓷相对所制备的陶瓷涂层表面孔隙具有填补作用,使陶瓷涂层表面均匀平整致密,孔隙、缝隙基本消失,解决了金属粉末活性填料的分散问题。     

Detection by Multiple Trellises

In this paper, we present a novel pragmatic approach, referred to as detection by multiple trellises, to perform trellis-based detection over realistic channels. More precisely, we consider channels with unknown parameters and apply the concept of detection by multiple trellises to forward-backward (FB) algorithms. The key idea of our approach consists, first, of properly quantizing the channel parameters and, then, considering replication of coherent FB algorithms operating on parallel trellises, one per hypothetical quantized value. In order to make the receiver robust against a possibly time-varying channel parameters, the proposed soft-output algorithms perform a proper ?manipulation? of the forward and backward metrics computed by the parallel FB algorithms at regularly spaced trellis steps. We consider two significant examples of application: detection over (i) phase-uncertain channels and (ii) fading channels. The performance of the proposed algorithms is investigated considering differentially encoded (DE) quaternary phase shift keying (QPSK) and iterative detection schemes based on low-density parity-check (LDPC) codes. Besides having a low complexity, the proposed soft-output algorithms turn out to be robust, flexible, blind, in the sense that no knowledge of the channel parameter statistics is required, and highly parallelizable, as it is desirable in high-throughput future wireless communication systems.     

Personal communications by satellite

Personal communications (PC) refers to two-way voice (and possibly data) communications to a small hand-held unit, capable of being carried by a person and used in various locations. PC via satellite refers to the case where this hand-held unit communicates directly with a satellite to provide the duplex voice (or data) service. Both geosynchronous earth orbit (GEO) and low earth orbit (LEO) satellites have been considered to provide this service. GEO and LEO satellite systems must compete with existing mobile cellular radio systems both in meeting performance requirements and service costs, if they are to be a significant supplier of PC services. GEO and LEO systems each have unique advantages and disadvantages when used to provide a PC service. While these general characteristics are identified in Section 1 of the paper, a more quantitative comparison is needed. This quantitative comparison is made by comparing a GEO PC satellite system, operating at EHF (K_a-band) frequencies with a LEO system operating at UHF (L-band) frequencies, including service costs for both systems. The two systems used in the comparison are examples of realistic GEO and LEO system designs for PC service, and although it is not exhaustive, the comparison points out some of the key differences between GEO and LEO systems that affect service performance and cost.     

VUV generation by high-order CARS

Generation of VUV (vacuum ultraviolet) radiation by stimulated Raman scattering (SRS) in H₂ is studied with collinear irradiation of the first Stokes component simultaneously with pump laser radiation. Improvements of the high-order coherent anti-Stokes Raman scattering (CARS) method over the pure SRS scheme are: generation of higher anti-Stokes (AS) orders, increased conversion efficiency, and considerably better reproducibility. Experimental results are presented to confirm the theoretical analysis     

Temperature control by chip-implemented adaptive recurrent fuzzy controller designed by evolutionary algorithm

Online adaptive temperature control by field-programmable gate array (FPGA) - implemented adaptive recurrent fuzzy controller (ARFC) chip is proposed in this paper. The RFC is realized according to the structure of Takagi-Sugeno-Kang (TSK)-type recurrent fuzzy network. Direct inverse control configuration is used. To design RFC offline, evolutionary fuzzy controller using the hybrid of the Simplex method and particle swarm optimization (SPSO) is proposed. In SPSO, each RFC corresponds to a particle, and all the free parameters in RFC are optimally searched. We use the PSO to find a good solution globally, and the incorporation of the Simplex method helps find a better solution around the local region of the best solution found by PSO so far. Then, online adaptive temperature control with ARFC chip implemented by FPGA is proposed. In the ARFC chip, the consequent parameters of all rules are all tuned online using gradient descent. To verify the performance of the ARFC chip, experiments on a water bath temperature system are performed.     

ENIG Corrosion Induced by Second-Phase Precipitation

Materials analysis of a flip-chip package lot with solder bump interconnect failures revealed a new mechanism for corrosion of electroless nickel immersion gold surface finish. Detailed scanning and transmission electron microscopy (SEM and TEM) in conjunction with focused ion beam microscopy and electron dispersion analysis of the unsoldered ball grid array substrate pads on packages that exhibited flip-chip solder bump interconnect failures revealed an unusual and subtle defect in the original Ni(P) layer, which was ultimately responsible for flip-chip joint failure. Detailed TEM analysis of the defect regions showed that they consisted of Ni(P) particles of slightly different composition than the bulk Ni(P) layer. Microstructure changes around these incorporated particles indicated that the second-phase particles were deposited from the plating bath during the Ni(P) growth stage. The second-phase particles provided additional surface area for nucleation and growth of Ni(P). Ultimately, a low-density boundary region in the growing Ni(P) layer formed where the particle-induced growth front and the planar Ni(P) film growth front intersected. This low-density interface eventually terminated at the surface of the Ni(P) layer. In addition the growth from the second-phase particle created localized surface topology that was different than that of the surrounding Ni(P) layer. The low-density interfaces as well as the surface topology led to enhanced corrosion of the Ni(P) layer when exposed to the immersion gold plating process. In some cases the corrosion was severe enough to create voids in the Ni(P) layer. The exposed, oxidized Ni(P) surfaces in and around these enhanced corrosion regions did not wet when exposed to solder. This led to degradation in the strength of the solder joint and subsequent solder interconnect failure.     

Polymer Inverter Fabricated by Inkjet Printing and Realized by Transistors Arrays on Flexible Substrates

We have fabricated organic thin-film transistors (OTFTs) and implemented inverters on flexible substrates using polythiophene (PHT) as the semiconductor and polyvinylphenol (PVP) as the gate dielectric. The semiconductor was defined by inkjet printing. The poor consistency of the printing process has affected the uniformity of inkjet-printed OTFTs enormously. We also proposed a method to increase the yield by incorporating a pre-testing step during circuit fabrication. We designed and fabricated a basic unit of circuits called a thin-film transistor (TFT) array. These devices were then connected to each other to form a gate via printed nano-silver. To verify the implementation flow, we designed and measured bootstrap inverters and ring oscillator composed of them. The five-stage ring oscillator has been fabricated and oscillated at the frequency, 60 Hz, when the supply voltage is 40 V      

Signal enhancement by time-frequency peak filtering

Time-frequency peak filtering (TFPF) allows the reconstruction of signals from observations corrupted by additive noise by encoding the noisy signal as the instantaneous frequency (IF) of a frequency modulated (FM) analytic signal. IF estimation is then performed on the analytic signal using the peak of a time-frequency distribution (TFD) to recover the filtered signal. This method is biased when the peak of the Wigner-Ville distribution (WVD) is used to estimate the encoded signal's instantaneous frequency. We characterize a class of signals for which the method implemented using the pseudo WVD is approximately unbiased. This class contains deterministic bandlimited nonstationary multicomponent signals in additive white Gaussian noise (WGN). We then derive the pseudo WVD window length that gives a reduced bias when TFPF is used for signals from this class. Testing of the method on both synthetic and real life newborn electroencephalogram (EEG) signals shows clean recovery of the signals in noise level down to a signal-to-noise ratio (SNR) of -9 dB.     

A comparison by simulation and by measurement of the substrate noise generated by CMOS, CSL, and CBL digital circuits

Current-steering logic (CSL) and current-balanced logic (CBL) are logic families that have been proposed with the objective of reducing the substrate noise in mixed-signal integrated circuits. These two families are compared here with conventional CMOS by simulation, using a substrate model extracted from the layouts, and also by measurements on a test chip. With small, low-power cells, noise reduction of CSL and CBL with respect to CMOS is only marginal; the same result is obtained with large, high-power (buffer) cells, if the supply wire inductance is very low. For large cells with typical wire bonding supply inductance (of the order of 10 nH), CBL cells provide significant noise reduction and are more effective than CSL cells; these become even noisier than CMOS cells for large inductance values. The results here, considering the real substrate noise, are more reliable than previous evaluations considering only the amplitude of the supply current spikes.     

国际电联的电信管理网体系结构

文章简述了国际电联在其Ｍ．３０１０建议中提出的电信管理网体系结构中，即：“信息结构”，“功能结构”和“物理结构”，并预测电信管理网今后的发展方向。     

Electromagnetic scattering by a curved plate--Solution by uniform asymptotic theory of diffraction

The uniform asymptotic theory (UAT) of diffraction has been applied to find the monostatic scattered field by curved plate with a plane wave illumination with electric field parallel to the edge. The solution is valid for all positions of the receiver and is uniform around the reflection boundaries. The theoretical monostatic radar cross section (RCS) shows good agreement with experimental results. The formulation works very well for arbitrary radius of curvature of the plate down to a value oflambda/2.     

Demosaicing by successive approximation.

In this paper, we present a fast and high-performance algorithm for color filter array (CFA) demosaicing. CFA demosaicing is formulated as a problem of reconstructing correlated signals from their downsampled versions with an opposite phase. The major contributions of this work include (1) a new iterative demosaicing algorithm in the color difference domain and (2) a spatially adaptive stopping criterion for suppressing color misregistration and zipper artifacts in the demosaiced images. We have compared the proposed demosaicing algorithm with two current state-of-the-art techniques reported in the literature. Ours outperforms both of them on demosaicing performance and computational cost.     

Evaluating MAPSec by marking attack graphs

MAPSec has recently been introduced as a security protocol for mobile telecommunication networks in the midst of numerous threats and vulnerabilities. Our initial study reveals that MAPSec can only provide protection coverage to a minor portion of the total network vulnerabilities. Motivated by this discovery, we have devised a toolkit—Cellular Network Vulnerability Assessment Toolkit for Evaluation (eCAT) to identify: (1) Exact protection coverage of MAPSec, in terms of percentage of attacks prevented; (2) Other kinds of security protocols required in addition to MAPSec; and (3) The most vulnerable network areas. We use the results from eCAT in Coverage Measurement Formulas (CMF) to identify other vulnerabilities. Results from eCAT are dually useful in that they not only reveal MAPSec’s limited effectiveness but also provide insights into overall network vulnerabilities.     

计算全息衍射光学代码的设计

提出了应用二元计算全息（ＢＣＧＨ）的方法来设计和制作一种新型的衍射光学代码（ＤＯＣ），并采用振幅补偿的方法来保证正确的可译性和实现高信噪比。还将其与Ｓ．Ｊ．Ｂｅｖｅｒ等人提出的相位整形方法制作的衍射光学条码（ＤＯＢＣ）的结果进行了比较，分析结果表明这种方法制作的ＤＯＣ具有能完全正确解译、低恢复误差、高信噪比等特点     

Correction of deflection-aberrations by analog computer

For wide-angle deflection (±25°) of microspot tubes (spot size-8 microns), dynamic correction of focal length (DCF) alone is no longer capable of conserving resolution. It is found, however, that complete recovery of ultra-high resolution (3000 lines per inch) is practical by adding dynamic correction of astigmatism (DCA) to DCF. The laws of error distribution on the tube face are found to be quadratic functions of position coordinatesxandy. Dynamic correction thus requires an ideal product generator that obeys the associative law of multiplication out to large amplitudes. A special beam-deflection type of computer tube has been developed. It operates on the principle of deflecting a square beam across a quadrantal target. An analog computer using three of these "roving-square tubes" (RST's) generates all three dynamic corrections as required by DCF and DCA. Photographs of deflected television microimages show the effectiveness of this analog computer in presenting approximately 9000 spot diameters, or 80 million dots, within a 3-inch square.     

Transistor-degradation prediction by time-series analysis

In silicon bipolar junction transistors, electrostatic discharge (ESD) is known to accelerate the degradation of the current gain factor β, which follows a pattern similar to that caused by thermal stress or ionizing irradiation. We use autoregressive integrated moving-average (ARIMA) models to predict the degradation of β from ESD-or life-test data.     

Polymer solar cell by blade coating

Polymer bulk hetero-junction solar cells of poly(3-hexylthiophene) (P3HT) donor and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) acceptor are fabricated by blade coating in toluene solution. Desired donor–acceptor self-organization is achieved without the slow drying process and high boiling point solvent. Power conversion efficiency is 3.8%, much higher than the 2.6% obtained by spin coating in toluene solution. The blade coating method has nearly 100% material usage and can be integrated in the roll-to-roll process with high throughput production.