Subcarrier grouping with environmental sensing for MIMO‐OFDM systems over correlated double‐selective fading channels

Multiple‐Input, Multiple‐Output (MIMO)‐orthogonal frequency division multiplexing (OFDM) is a promising technique in 5G wireless communications. In high‐mobility scenarios, the transmission environments are time‐varying and/or the relative moving velocity between the transmitter and receiver is also time‐varying. In the literature, most of previous works mainly focused on fixed subcarrier group size and precoded the MIMO signals with unitary channel state information. In this way, the subcarrier grouping may naturally lead to big loss of channel capacity in high‐mobility scenarios because of the channel state information difference on the subcarriers in each group. To employ the MIMO‐OFDM technique, adaptive subcarrier grouping scheme may be an efficient way. In this paper, we first consider MIMO‐OFDM systems over double‐selective i.i.d. Rayleigh channels and investigate the quantitative relation between subcarrier group size and capacity loss theoretically. With developed theoretical results, we also propose an adaptive subcarrier grouping scheme to satisfy the preset capacity loss threshold by adjusting grouping size with the sensed environmental information and mobile velocity. Theoretical analysis and simulation results show that to achieve a better system capacity, a sparse scattering, lower signal‐to‐noise ratio, and lower velocity as well as properly large antenna number are matched with larger subcarrier group size. One important observation is that if the antenna number is too large and higher than a threshold, which will not bring any additional gain to the subcarrier grouping. That is, the system capacity loss will converge to a lower bound expeditiously with respect to antenna number, which is given in theory also. Copyright © 2016 John Wiley & Sons, Ltd.     

EPS的STL模型连续热切割技术加工研究

基于STL(标准模板库)模型投影轮廓的连续切割技术对EPS(聚苯乙烯)建筑模型加工进行研究,提出了分组矩阵切片算法,并在每组中建立局部拓扑关系提高分层切片的效率,结合截面轮廓求并算法,应用于投影轮廓连续切割技术,解决了非对称曲面在加工过程中与热丝的干涉难题。开发出基于STL模型投影轮廓轨迹的自动编程系统,以此作为软件平台结合五自由度建筑初模的数控热切割加工装置的硬件设施,实现了建筑模型加工。实验结果表明,该系统能高效、准确加工出所设计的建筑模型。     

CA系统中基于用户分组的EMM分发机制

提出了一种新颖的用户分组机制以降低条件接收系统的复杂度.与传统密钥分发机制相比,该方案在保证系统安全性并实现条件接收系统功能的前提下,大大减少了系统中授权管理信息的数据量,提高了系统的业务管理效率.     

有序用电避峰预案优化编制方法研究

针对有序用电管理工作中的避峰专项预案编制展开研究。基于有序用电精细化管理理念,以公平合理性为总原则,辅以经济性要求,设计了避峰预案的编制流程,并提出了避峰预案分级分组的概念。首先,利用综合评价方法确定各用户参与避峰的优先级,并形成避峰序位表。然后根据避峰序位和可避峰负荷大小对用户进行分组。最后依据用户组的顺序安排机制,并以社会避峰损失最小为目标,优化各级避峰负荷的用户组构成。算例分析结果表明,上述避峰预案编制方法能保证避峰优先级综合评价值较小的用户优先参与避峰,提高预案的科学合理和公平性;有效反映产业结构调整、用户节能减排和保护环境等政策导向;同时避免传统方式下部分大用户避峰损失过大。     

探析小煤矿安全生产困境及其治理模式

根据小煤矿治理的现存困境和治理目标,结合小煤矿问题特点与原因,提出了国有集团化治理模式的设想,并且认为:新的煤炭国有集团应采取"外部市场+内部计划"的方式来安排集团内部的大矿井和小煤矿的生产计划,以满足煤炭市场的波动性需求,同时实现集团整体安全生产,全力防止煤炭非法生产,从而解决小煤矿问题的治理困境。     

Grouping and gambling: A Gestalt approach to understanding the gambler's fallacy.

The gambler's fallacy was examined in terms of grouping processes. The gambler's fallacy is the tendency to erroneously believe that for independent events, recent or repeated instances of an outcome (e.g., a series of "heads" when flipping a coin) will make that outcome less likely on an upcoming trial. Grouping was manipulated such that a critical trial following a run of heads or tails was grouped together with previous trials (i.e., the last trial of "Block 1") or was the first trial of another group (the first trial of "Block 2"). As predicted, the gambler's fallacy was evident when the critical trial was grouped with the previous trials, but not when it was arbitrarily grouped with the next block of trials. Discussion centres on the processes underlying the gambler's fallacy and practical implications of these findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

邯郸重污染日空气质量预测研究

针对数据样本较少,且时间序列不连续的邯郸重度污染日的空气质量指标数据,采用基于数据分组的分数阶GM(1,1)模型(The data grouping GM(1,1) model with fractional order accumulation,简称DGFGM(1,1)),对邯郸地区2018—2019年12月28、29、30日三天的AQI及PM_(2. 5)、PM_(10)、NO_2的日均浓度进行预测。使用该模型预测的AQI、PM_(2. 5)、PM_(10)和NO_2的MAPE分别为2. 89%、3. 28%、3. 83%、3. 23%,表明DGFGM(1,1)模型具有良好的预测性能。预测结果显示,在当前的治理力度下,邯郸地区空气重污染的发生仍然难以避免,有些污染物浓度不降反升,除2018—2019年的12月30日的NO_2外,其他时间的所有污染物浓度全部超过标准限值,污染情况相当严重。当地有关部门应重视对极端重度污染天气的预防和治理,使得大气环境质量得以全面提升。     

基于载波聚合的下行调度研究

现有LTE-A系统中,由于接入载波能力的差异,LTE用户的性能往往得不到保证。针对这一问题,提出了一种新的联合载波调度的资源分配方案,该方案根据用户类型划分UE所能接入的载波资源组,在后向兼容载波较为紧张时,使LTE-A用户以更大的概率接入到非后向兼容载波,从而保证LTE用户的性能。同时,该方案引入载波选择权重的计算,作为改进的比例公平(Proportional Fair,PF)算法的一个因子,能够实时保证载波间的负载均衡,提升系统吞吐量。     

基于像素分组的帧内预测快速算法

为了降低HEVC帧内编码的复杂度,基于HM 12.0提出了一种帧内预测快速算法.首先将35种预测方向分成5组,然后基于像素提取PU块的梯度方向信息并匹配到其中一组,最后在RDO运算时根据统计信息适当降低了候选模式的数量.实验结果表明,与JCTVC最新源码HM 12.0相比,该算法平均能够节省20％的编码时间,峰值信噪比和码率变化不大.     

A fast and efficient color image enhancement method based on fuzzy-logic and histogram

A new fuzzy logic and histogram based algorithm for enhancing low contrast color images has been proposed here. The method is computationally fast compared to conventional and other advanced enhancement techniques. It is based on two important parameters M and K, where M is the average intensity value of the image, calculated from the histogram and K is the contrast intensification parameter. The given RGB image is converted into HSV color space to preserve the chromatic information contained in the original image. To enhance the image, only the V component is stretched under the control of the parameters M and K. The proposed method has been compared with conventional contrast enhancement techniques as well as with advanced algorithms. All the above techniques were based on the principle of transforming the skewed histogram of the original image into a uniform histogram. The performance of the different contrast enhancement algorithms are evaluated based on the visual quality, Tenengrad, CII and the computational time. The inter comparison of different techniques was carried out on different low contrast color images. Based on the performance analysis, we advocate that our proposed Fuzzy Logic method is well suited for contrast enhancement of low contrast color images.