A Concatenated ML Decoder for ST／SFBC-OFDM Systems in Double Selective Fading Channels

This paper presented a concatenated maximum-likelihood (ML) decoder for space-time/space-frequency block coded orthogonal frequency diversion multiplexing (ST/SFBC-OFDM) systems in double selective fading channels. The proposed decoder first detects space-time or space-frequency codeword elements separately. Then,according to the coarsely estimated codeword elements, the ML decoding is performed in a smaller constellation element set to searching final codeword. It is proved that the proposed decoder has optimal performances if and only if subchannels are constant during a codeword interval. The simulation results show that the performances of proposed decoder is close to that of the optimal ML decoder in severe Doppler and delay spread channels. However,the complexity of proposed decoder is much lower than that of the optimal ML decoder.     

Guillain-Barre综合征早期电生理变化及分型再认识

分析了31例Guillain－Barre综合征（GBS）的电生理改变。有14例于病后3周行肌电图检查。早期运动神经传导速度（MCV）异常率为71．01％，主要表现为末端潜伏时（ML）延长，占61．22％，其次为MCV轻度减慢，而感觉神经传导速度（SCV）及肌电图（EMG）对早期GBS的诊断价值有限．但EMG鼻常出现越早，则预后越差。31例电生理特点分型：髓鞘型GBS27例（87．09％），轴索型GBS2例（6．4％），另有2例（6．4％）髓鞘及轴索损害均较重，预后差，故认为可能是两者同时损害的混合型。     

轮毂螺母垫片断裂失效分析

材料为ML40Cr的车轮轮毂螺母在装配后发现垫片断裂失效现象,通过宏观检查、断口分析、金相检测、硬度检测、化学成分分析、综合分析分析、氢含量测定等方法对垫片断裂原因进行分析。结果表明:垫片表面在挤压过程中产生的微裂纹,在酸洗、镀锌等过程中,氢沿裂纹渗入基体,由于垫片硬度要求较高,从而导致氢脆开裂并扩展。最终在装配应力作用下发生断裂失效。     

准正交空时分组码的设计与性能分析

本文分析了现有的几种准正交空时分组码的结构,在此基础上提出了一种新的四天线准正交分组码编码方案,丰富了四天线准正交空时分组码的可用码字。仿真结果表明,在不增加译码复杂度的情况下,新的编码方案性能接近于TBH码和Jafarkhani码。比较了最大似然译码算法和最小均方误差译码算法,仿真结果表明,最小均方误差译码算法对新的准正交分组码具有较好的检测性能,译码复杂度降低。     

Guillain-Barre综合征早期电生理变化及分型再认识

分析了31例Guillain－Barre综合征（GBS）的电生理改变。有14例于病后3周行肌电图检查。早期运动神经传导速度（MCV）异常率为71．01％，主要表现为末端潜伏时（ML）延长，占61．22％，其次为MCV轻度减慢，而感觉神经传导速度（SCV）及肌电图（EMG）对早期GBS的诊断价值有限．但EMG鼻常出现越早，则预后越差。31例电生理特点分型：髓鞘型GBS27例（87．09％），轴索型GBS2例（6．4％），另有2例（6．4％）髓鞘及轴索损害均较重，预后差，故认为可能是两者同时损害的混合型。     

Progress and Perspective of Artificial Intelligence and Machine Learning of Prediction in Anesthesiology

Artificial intelligence (AI) has long been an attractive topic in medicine,especially in light of the rapid developments in digital and information technologies.AI has already provided some breakthroughs in medicine.With the assistance of AI,more precise models have been used for clinical predictions,diagnoses,and decision-making.This review defines the basic concepts of AI and machine learning (ML),and provides a simple introduction to certain frequently used algorithms in AI and ML.In addition,the review discusses the current common applications of AI and ML in the prediction of anesthesia conditions,including those for preoperative predictions of difficult airways,intraoperative predictions of adverse events and anesthetic effects,and postoperative predictions of vomiting and pain.The use of AI in anesthesiology remains in development,even without extensive promotion and clinical application;moreover,it has immense potential to maintain further development in the future.Finally,the limitations and challenges of AI development for anesthesia are also discussed,along with considerations regarding ethics and safety.     

Improved List Sphere Decoder for Multiple Antenna Systems

An improved list sphere decoder （ILSD） is proposed based on the conventional list sphere decoder （LSD） and the reduced- complexity maximum likelihood sphere-decoding algorithm. Unlike the conventional LSD with fixed initial radius, the ILSD adopts an adaptive radius to accelerate the list cdnstruction. Characterized by low-complexity and radius-insensitivity, the proposed algorithm makes iterative joint detection and decoding more realizable in multiple-antenna systems. Simulation results show that computational savings of ILSD over LSD are more apparent with more transmit antennas or larger constellations, and with no performance degradation. Because the complexity of the ILSD algorithm almost keeps invariant with the increasing of initial radius, the BER performance can be improved by selecting a sufficiently large radius.     

基于DDS的正弦信号发生电路设计

针对某检测设备的信号源需要,以Micro Linear公司的单片正弦信号发生芯片ML2035为核心,利用计数器与逻辑门电路完成了一种简易正弦信号发生电路的设计。采用四变量卡洛图方法完成了电路的逻辑设计,使用74HC4002、74HC4060和外围元件完成控制字电路的具体实现。结论表明使用ML2035和简单逻辑电路构成的特定频率正弦信号发生电路具有简单可靠的特点,设计方法对于特定场合的应用具有借鉴意义。