Unified spatial diversity combining and power allocation for CDMAsystems in multiple time-scale fading channels

In a mobile wireless system, fading effects can be classified into large-scale (long-term) effects and small-scale (short-term) effects. We use transmission power control to compensate for large-scale fading and exploit receiver antenna (space) diversity to combat small-scale fading. We show that the interferences across the antennas are jointly Gaussian in a large system, and then characterize the signal-to-interference ratio for both independent and correlated (across the antennas) small-scale fading cases. Our results show that when each user's small-scale fading effects are independent across the antennas, there is a clear separation between the gains of transmission power control and diversity combining, and the two gains are additive (in decibels). When each user's small-scale fading effects are correlated across the antennas, we observe that, in general, the gains of transmission power control and diversity combining are coupled. However, when the noise level diminishes to zero, using maximum ratio combining “decouples” the gains and achieves the same diversity gain as in the independent case. We then characterize the Pareto-optimal (minimum) transmission power allocation for the cases of perfect and noisy knowledge of the desired user's large-scale fading effects. We find that using antenna diversity leads to significant gains for the transmission power     

An optimal checkpointing-strategy for real-time control systemsunder transient faults

Real-time computer systems are often used in harsh environments, such as aerospace, and in industry. Such systems are subject to many transient faults while in operation. Checkpointing enables a reduction in the recovery time from a transient fault by saving intermediate states of a task in a reliable storage facility, and then, on detection of a fault, restoring from a previously stored state. The interval between checkpoints affects the execution time of the task. Whereas inserting more checkpoints and reducing the interval between them reduces the reprocessing time after faults, checkpoints have associated execution costs, and inserting extra checkpoints increases the overall task execution time. Thus, a trade-off between the reprocessing time and the checkpointing overhead leads to an optimal checkpoint placement strategy that optimizes certain performance measures. Real-time control systems are characterized by a timely, and correct, execution of iterative tasks within deadlines. The reliability is the probability that a system functions according to its specification over a period of time. This paper reports on the reliability of a checkpointed real-time control system, where any errors are detected at the checkpointing time. The reliability is used as a performance measure to find the optimal checkpointing strategy. For a single-task control system, the reliability equation over a mission time is derived using the Markov model. Detecting errors at the checkpointing time makes reliability jitter with the number of checkpoints. This forces the need to apply other search algorithms to find the optimal number of checkpoints. By considering the properties of the reliability jittering, a simple algorithm is provided to find the optimal checkpoints effectively. Finally, the reliability model is extended to include multiple tasks by a task allocation algorithm     

DC offset calibration method for zero-IF receiver removing the PGA-gain-correlated offset residue

This paper presents a novel DC offset calibration method for the zero-IF (intermediate frequency) receiver that removes the PGA-gain-correlated offset residue. The conventional calibration method usually uses the classic input/output referred offset model, in which the receiver IF programmable gain amplifiers (PGAs) have offset sources that varies a lot with different gain settings. Consequently, the conventional calibration method needs to generate the calibration code at each gain step and requires a huge look up table (LUT) to store the calibration values. This paper presents a new DC offset model which is gain non-correlated, by analyzing two types of commonly used PGA. Based on the new model, a LUT-free single-step DC offset calibration method in together with the implementation circuit is designed. The proposed method has been verified on a practical zero-IF receiver circuit in a standard 0.18 μm CMOS technology through the Monte Carlo (MC) simulation. The simulation results show that the receiver IF output offset residue after calibration using the proposed method is reduced to below 12 mV, in contrast to 200 mV by the conventional method.     

Luminescence,charge mobility,and optical waveguiding of two-dimensional organic rubrene nanosheets: Comparison with one-dimensional nanorods

Intrinsic characteristics of organic and inorganic nanostructures depend on their physical dimensions (i.e., size and shape) and crystallinity. Here, we compared the nanoscale optical and electrical properties of organic rubrene one-dimensional (1-D) nanorods (NRs) and two-dimensional (2-D) nanosheets (NSs). From high-resolution laser confocal microscope photoluminescence (PL) measurements, the light-emission characteristics of 2-D rubrene NSs varied with the crystalline domain direction, indicating intrinsic PL anisotropy, which was distinguishable from 1-D rubrene single NRs, because of anisotropy π–π stacking molecular arrangements. We also observed the variation of charge carrier mobility depending on the measured directions (i.e., anisotropy of charge transport) in rubrene NS-based field-effect transistors. The optical waveguiding properties of rubrene nanostructures were strongly correlated to the dimensionality of materials and PL anisotropy.     

辽宁省广播电视内容智能监测系统介绍

介绍在当前广播电视发展的情况下,如何采用高新技术对广播电视播出内容进行高效、准确、全面的监测和管理,着重介绍在现有的网络基础上采用特征提取及比对技术搭建能够满足广播电视内容监测要求的智能监测系统以及该系统能够实现的功能。     

A gm-boosted common-gate CMOS low-noise amplifier with high P1dB

A 2.4-GHz transconductance (g_m)—boosted common gate (CG) low-noise amplifier (LNA) with a high 1-dB compression point (P1dB) is proposed. To overcome the constraint of conventional CG LNA for input-mismatching, RF filters consisting of band-stop and high-pass filter are used as a load and inter-stage matching components, respectively. Therefore, the g _m can be freely increased for a high gain and low noise figure (NF) without decreasing input impedance. Moreover, the linearity is also enhanced because band-stop filter load can reduce 2nd harmonics. The fully integrated LNA implemented by 0.18-µm RF CMOS technology delivers an input P1dB of ?1 dBm, a power gain of 14.8 dB and a NF of 3.7 dB. The LNA consumes 8.2 mA at a supply voltage of 1.8 V.     

Numerical Optimization of an Active Voltage Controller for High-Power IGBT Converters

Feedback control of insulated gate bipolar transistors (IGBTs) in the active region can be used to regulate the device switching trajectory. This facilitates series connection of devices without the use of external snubber networks. Control must be achieved across the full active region of the IGBT and must balance a number of conflicting system goals including diode recovery. To date, the choice of control parameters has been a largely empirical process. This paper uses accurate device models and formalized optimization procedures to evaluate IGBT active voltage controllers. A detailed optimization for the control of IGBT turn-on is presented in this paper     

Retraction: 3D Printing of Bilineage Constructive Biomaterials for Bone and Cartilage Regeneration

Adv. Funct. Mater. 2017 , 27, 1703117 DOI: 10.1002/adfm.201703117 The above article, first published online on 31 July 2017 in Wiley Online Library ( https://doi.org/10.1002/adfm.201703117 ) and corrected on 19 March 2019 ( https://doi.org/10.1002/adfm.201900376 ) has been retracted by agreement with the authors, the journal Editor‐in‐Chief, and Wiley‐VCH Verlag GmbH & Co. KGaA. The retraction has been agreed upon due to several flawed figures as published in the article, containing duplicate images, which calls the validity of these data into question. Reference C. Deng, Q. Yao, C. Feng, J. Li, L. Wang, G. Cheng, M. Shi, L. Chen, J. Chang, C. Wu, Adv. Funct. Mater. 2017 , 27, 1703117.     

Distance-Enhancing Constrained Codes with Parity-Check Constraints for Data Storage Channels

This paper proposes efficient distance-enhancing constrained codes with parity-check (PC) constraints for data storage channels. We first propose simple and efficient finitestate encoding methods to design various distance-enhancing constrained codes, including a repeated minimum transition runlength (RMTR) code for optical recording channels, as well as a maximum transition run (MTR) code for magnetic recording channels. We further propose a general and systematic code design methodology, which can efficiently combine constrained codes with PC codes. The constrained codes can be any distanceenhancing constrained codes. The PC codes can be any linear binary PC codes. The rates of the designed codes are only a few tenths of a percent below the theoretical maximum. The proposed method enables soft information to be available to the PC decoder and soft decoding of PC codes. Examples of several newly designed distance-enhancing constrained PC codes are illustrated. Simulation results with blu-ray disc (BD) systems show that the proposed new RMTR code and RMTR constrained 4-bit PC code perform 0.2 dB and 0.85 dB better than the standard 17PP code, respectively, at error correction code (ECC) failure rate (EFR) of 10^-12 and high recording density.