Kernel-based deterministic annealing algorithm for data clustering

Data clustering in kernel-induced feature space is interesting in that, by nonlinearly mapping the observed data from a low-dimensional input space into a high (possibly infinite)-dimensional feature space by means of a given kernel function, the kernel-based clustering can reveal complicated (e.g. linearly nonseparable) data structures that may be missed by traditional clustering methods in the standard Euclidean space. A kernel-based deterministic annealing (KDA) algorithm is developed for data clustering by using a Gaussian kernel function. The Gaussian parameter (width), which determines the nonlinear mapping together with the Gaussian kernel, is adaptively selected by the scaled inverse of data covariance. The effectiveness of the Gaussian parameter (width) selection method and the superiority of the KDA algorithm for clustering a variety of data structures are supported by the experimental results on artificial and real data sets     

Nonlinear Transient and Distortion Analysis via Frequency Domain Volterra Series

This paper presents a novel approach for transient and distortion analyses for time-invariant and periodically time-varying mildly nonlinear analog circuits. Our method is based on a frequency domain Volterra series representation of nonlinear circuits. It computes the nonlinear responses using a nonlinear current method that recursively solves a series of linear Volterra circuits to obtain linear and higher-order responses of a nonlinear circuit. Unlike existing approaches, where Volterra circuits are solved mainly in the time domain, the new method solves the linear Volterra circuits directly in the frequency domain via an efficient graph-based technique, which can derive transfer functions for any large linear network efficiently. As a result, both frequency domain characteristics, like harmonic and intermodulation distortion, and time domain waveforms can be computed efficiently. The new algorithm takes advantage of identical Volterra circuits for second- and higher-order responses, which results in significant savings in driving the transfer functions. Experimental results for two circuits—a low-noise amplifier and a switching mixer—are obtained and compared with SPICE3 to validate the effectiveness of this method.     

On the complexity of and algorithms for finding the shortest path with a disjoint counterpart

Finding a disjoint path pair is an important component in survivable networks. Since the traffic is carried on the active (working) path most of the time, it is useful to find a disjoint path pair such that the length of the shorter path (to be used as the active path) is minimized. In this paper, we first address such a Min-Min problem. We prove that this problem is NP-complete in either single link cost (e.g., dedicated backup bandwidth) or dual link cost (e.g., shared backup bandwidth) networks. In addition, it is NP-hard to obtain a K-approximation to the optimal solution for any K>1. Our proof is extended to another open question regarding the computational complexity of a restricted version of the Min-Sum problem in an undirected network with ordered dual cost links (called the MSOD problem). To solve the Min-Min problem efficiently, we introduce a novel concept called conflicting link set which provides insights into the so-called trap problem, and develop a divide-and-conquer strategy. The result is an effective heuristic for the Min-Min problem called COnflicting Link Exclusion (COLE), which can outperform other approaches in terms of both the optimality and running time. We also apply COLE to the MSOD problem to efficiently provide shared path protection and conduct comprehensive performance evaluation as well as comparison of various schemes for shared path protection. We show that COLE not only processes connection requests much faster than existing integer linear programming (ILP)-based approaches but also achieves a good balance among the active path length, bandwidth efficiency, and recovery time.     

一种低压低功耗SRAM/SOI单元设计

提出一种改进4管自体偏压结构SRAM/SOI单元.基于TSUPREM4和MEDICI软件的模拟和结构性能的分析,设计单元结构并选取结构参数.该结构采用nMOS栅下的含p 埋沟的衬底体电阻代替传统6管CMOSSRAM单元中的pMOS元件,具有面积小、工艺简单的优点.该结构可以在0.5V的电源电压下正常工作,与6管单元相比,该单元瞬态响应正常,功耗只有6管单元的1/10,满足低压低功耗的要求.     

Injection-locked Fabry-Pe/spl acute/rot laser with electronic feedback for clock recovery from high-speed OTDM signals

We demonstrate the use of an injection-locked Fabry-Pe/spl acute/rot laser diode with electronic feedback for base-rate clock recovery in N/spl times/10 Gb/s optical time-division-multiplexing (OTDM) systems. Injection-locking enhances the resonance frequency of the laser and the electrical feedback achieves strong resonance at the base-rate frequency of the injected data streams, enabling ultrastable electrical clock signal generation at the base rate of 10 GHz. Experimental demonstrations for clock recovery at 10 GHz from 40-Gb/s OTDM data streams and 4-1 demultiplexing of the data using the extracted clock after fiber transmission is presented. The timing jitter measured in the recovered electrical clock is less than 0.25 ps.     

A self-timed divider using a new fast and robust pipeline scheme

This paper investigates the potential of self-timed property of differential cascode voltage switch logic (DCVSL) circuits, and examines architectural techniques for achieving self-timing in DCVSL circuits. As a result, a fast and robust handshake scheme for dynamic asynchronous circuit design is proposed. It is novel and more general than other similar schemes. The proposed self-timed datapath scheme is verified by an 8-bit divider which is implemented using AMS 0.6-μm CMOS technology, and the chip size is about 1.66 mm×1.70 mm. The chip testing results show that the divider functions correctly and the latency for 8-bit quotient-digit generation is 17 ns (about 58.8 MHz)     

Optical signal generation at millimeter-wave repetition rates usingsemiconductor lasers with pulsed subharmonic optical injection

A new technique is presented and investigated systematically which generates optical signals at millimeter-wave repetition rates from a semiconductor laser, without the need for an intracavity saturable absorber. Optical pulses are generated from a long-cavity semiconductor laser with a repetition rate equal to its cavity resonant frequency by injecting short optical pulses at one of the cavity resonance subharmonics. A rate-equation model is proposed to explain the mechanism of this subharmonic optical injection method. Optical pulses with repetition rates of 35 and 56 GHz are generated using the proposed scheme from a semiconductor laser with a distributed Bragg reflector and a Fabry-Perot laser diode, respectively. The performance of the generated pulses is also evaluated in terms of detected RF power at the repetition frequencies, the subharmonic suppression ratio, phase noise, and timing jitter as a function of frequency detuning, injected optical power, laser bias current, and, finally, the subharmonic number. It is found that the generated optical pulses exhibit large subharmonic suppression ratio (>17 dB), large locking ranges >400 MHz, low levels of phase noise (~-93 dBc/Hz@10 kHz) and timing jitter (<0.41 ps over 100 Hz to 10 MHz), and large tolerance to variations in operating parameters     

Nitrogen implanted polysilicon resistor for high-voltage CMOStechnology application

A nitrogen-implanted polysilicon thin film resistor has been proposed to improve the electrical characteristics of resistors in high-voltage CMOS technologies. The SIMS profile shows the proposed nitrogen-implanted polysilicon resistor can raise 100 times of the concentration of nitrogen. Thereby, the temperature coefficient of resistance (TCR), voltage coefficient of resistance (VCR), and mismatch are improved 20.4%, 35.9%, and 23.5% in average, respectively. The improvements are attributed to the suppression of both hydrogen intrusion by the presence of high-nitrogen concentration in polysilicon     

Geometric and Electronic Structure-Matched Superoxide Dismutase-Like and Catalase-Like Sequential Single-Atom Nanozymes for Osteoarthritis Recession

Highly-active single-atom nanoenzymes (SAzymes) with biomimetic geometric and electronic coordination structures are highly highlighted to exhibit greatly-increased catalysis activity. Despite various SAzymes, superoxide dismutase (SOD)-like SAzymes for scavenging superoxide anions to treat osteoarthritis are still absent. In this report, a graphene-supported Cl Cu N₄-centered SAzyme (Cu N₄ClG) is engineered that carries out SOD-like reactions. Various synchrotron radiation-based X-ray valence/structural analyses reveal that the geometric and electronic structures of such Cl Cu N₄ active centers are validated to atomically match natural SOD enzyme after precisely manipulating coordinated N and Cl atoms via the unprecedented pre-coordination orientation and preservation of copper-phthalocyanine structure. Cu-N₄ClG SAzymes are endowed with unparalleled catalytic activities and kinetics to degrade O₂^•¯ into H₂O₂ and O₂, and further exhibit catalase (CAT)-like activity to sequentially decompose H₂O₂ and ^•OH into H₂O and O₂, wherein the origin of sequential SOD-like and CAT-like catalysis routes is uncovered. Impressively, nitroxide radical scavenging and photothermally-enhanced catalytic activity are reached, synergistically protecting chondrocytes from oxidative stress-induced apoptosis and alleviating osteoarthritis via re-programming or normalizing osteoarthritis microenvironments. Cu-N₄ClG SAzymes are competent for other reactive oxygen species (ROS)-arised lesions, and their rationales provide guidance to design other SAzymes.     

A Stable Polymer-based Solid-State Lithium Metal Battery and its Interfacial Characteristics Revealed by Cryogenic Transmission Electron Microscopy

Solid-state lithium metal batteries (SSLMBs) are a promising candidate for next-generation energy storage systems due to their intrinsic safety and high energy density. However, they still suffer from poor interfacial stability, which can incur high interfacial resistance and insufficient cycle lifespan. Herein, a novel poly(vinylidene fluoride‑hexafuoropropylene)-based polymer electrolyte (PPE) with LiBF₄ and propylene carbonate plasticizer is developed, which has a high room-temperature ionic conductivity up to 1.15 × 10⁻³ S cm⁻¹ and excellent interfacial stability. Benefitting from the stable interphase, the PPE-based symmetric cell can operate for over 1000 h. By virtue of cryogenic transmission electron microscopy (Cryo-TEM) characterization, the high interfacial compatibility between Li metal anode and PPE is revealed. The solid electrolyte interphase is made up of an amorphous outer layer that can keep intimate contact with PPE and an inner Li₂O-dominated layer that can protect Li from continuous side reactions during battery cycling. A LiF-rich transition layer is also discovered in the region of PPE close to Li metal anode. The feasibility of investigating interphases in polymer-based solid-state batteries via Cryo-TEM techniques is demonstrated, which can be widely employed in future to rationalize the correlation between solid-state electrolytes and battery performance from ultrafine interfacial structures.