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51.
介绍PAL制彩色全电视信号中色同步信号编码原理及恢复逐行倒相副载波的过程中,两种计算色同步信号相位角的方法。并且在实验的基础上得出:最小二乘法在PAL制电视信号的副载波相位角计算中不仅可以满足精度要求,而且简便灵活。  相似文献   
52.
Optic flow motion analysis represents an important family of visual information processing techniques in computer vision. Segmenting an optic flow field into coherent motion groups and estimating each underlying motion is a very challenging task when the optic flow field is projected from a scene of several independently moving objects. The problem is further complicated if the optic flow data are noisy and partially incorrect. In this paper, the authors present a novel framework for determining such optic flow fields by combining the conventional robust estimation with a modified genetic algorithm. The baseline model used in the development is a linear optic flow motion algorithm due to its computational simplicity. The statistical properties of the generalized linear regression (GLR) model are thoroughly explored and the sensitivity of the motion estimates toward data noise is quantitatively established. Conventional robust estimators are then incorporated into the linear regression model to suppress a small percentage of gross data errors or outliers. However, segmenting an optic flow field consisting of a large portion of incorrect data or multiple motion groups requires a very high robustness that is unattainable by the conventional robust estimators. To solve this problem, the authors propose a genetic partitioning algorithm that elegantly combines the robust estimation with the genetic algorithm by a bridging genetic operator called self-adaptation  相似文献   
53.
Carcinoma in ulcerative colitis (UC) develops from dysplastic precursor lesions, which include flat dysplasia (FD) and polypoid dysplasias (PD). PD may present as single or multiple polypoid structures or as plaque-like lesions that, independent of histological grade, are an indication for colectomy. PDs are histologically similar to adenomas and may not be readily distinguished by light microscopy. It is not known whether FD and PD are different entities, or whether they represent etiologically similar lesions with different morphological expression. We microdissected 25 cases of UC with PD and 19 samples of FD with surrounding chronic colitis (CC) in UC. Loss of heterozygosity (LOH) at the von Hippel Lindau (vHL) gene locus and the putative tumor suppressor genes APC, INK4A (9p16), and p53 was studied. LOH of the vHL gene, INK4A (9p16), and APC was also studied in 11 sporadic adenomas of the colon. LOH at the vHL locus was present in 50% of the samples of PD and in 12% of the samples of FD. LOH was seen in CC close to PD and FD in 26% and 12% of cases, respectively. No adenoma showed LOH of the vHL gene markers studied. LOH in p53 was seen in PD in 16% cases and in FD in 42% cases and in CC close to PD and FD in 0% and 14% cases, respectively. LOH patterns between PD and FD of the markers for APC and 9p16 were not different. LOH in APC was seen in two of five cases of adenoma. We conclude that PD and FD share genetic alterations in APC and 9p16 genes. More frequent involvement of the VHL gene in PD and surrounding CC and involvement of p53 in HGD and CC in FD may represent genetic differences between the development of PD and FD and may be the cause of the different morphology. The infrequency of LOH at the vHL locus in adenomas versus PD may serve as a discriminator between adenomas and PD in diagnostically problematic cases.  相似文献   
54.
本文从载流子连续性方程出发,采用半导体双异质结概念,从理论上推出了计算半导体光波导开关工作电流和速率的理论公式,为器件选取工作电流和提高开关速率提供了理论依据.  相似文献   
55.
越来越多的企业正在或者即将用SAP作为ERP的应用载体。企业在得益于ERP精细化管理的同时,往往也为ERP与其他子系统整合集成所烦恼。介绍了几种应用于SAP的接口技术,其中包括RFC、ALE-IDOC、BAPI、SAP-DCOM以及Web Service接口技术。并且在此基础上,列举了企业内部的一个实例,展现了SAP通过接口技术与外部的PDA移动终端系统整合,从而解决了维修服务行业从接收工单、记录维修、备件管理等在移动环境下的应用需求。  相似文献   
56.
针对城市车联网中出现的基站覆盖空洞及局部流量过载等问题,提出了一种基于车辆轨迹预测信息的动态预部署方案。首先,为了训练得到统一的seq2seq-GRU轨迹预测模型,多个携带边缘计算服务器的无人机在分布式联邦学习与区块链的架构下,去除中心聚合节点,采取改进的Raft算法,在每轮训练中根据贡献数据量的大小,选举得到节点来完成参数聚合及模型更新任务。其次,基于模型预测结果,提出了一种改进的虚拟力向导部署算法,通过各虚拟力来引导无人机进行动态地部署以提升车辆的接入率及通信质量。仿真结果表明,提出的训练架构能够加速模型的训练,部署算法在提升车辆接入率的同时提升了车辆与无人机之间的通信质量。  相似文献   
57.
Liu  Taoran  Cui  Jiancong  Zhuang  Hui  Wang  Hong 《Applied Intelligence》2021,51(11):8316-8333
Applied Intelligence - Pharmaceutical drug combinations can effectively treat various medical conditions. However, some combinations can cause serious adverse drug reactions (ADR). Therefore,...  相似文献   
58.
随着计算机技术及多媒体技术的发展,多媒体在教学中的应用越来越广泛,多媒体有着传统教学媒体不具备的独特优势,但在实际教学中也有不足之处,在教学中必须根据实际情况灵活运用多媒体才能取得理想的教学效果。  相似文献   
59.
A technique of symmetry analysis for modal characteristics in uniform waveguides or resonators with ferrite rods is presented here. Symmetry analysis can provide basic information concerning modal characteristics. After summarizing the basic principles of symmetry analysis, some points concerning symmetry operations are discussed. Then the process of symmetry analysis is applied to structures, i.e. uniform wave guides withC n symmetry or symmetry and resonators withD nh symmetry in which exist longitudinally magnetized ferrite rods. Finally, results of the symmetry analysis are given in four tables.  相似文献   
60.
Tongsh  Chasen  Liang  YiQi  Xie  Xu  Li  LinCai  Liu  Zhi  Du  Qing  Jiao  Kui 《中国科学:技术科学(英文版)》2021,64(10):2153-2165

The flow field is a pivotal part to manage the transport of water and gas in proton exchange membrane fuel cell. However, the reported water measurement methods (e.g., X-ray and electrochemical impedance spectroscopy (EIS)) cannot give a comprehensive understanding water distribution in the flow field, resulting in challenges in optimizing the channel design and enhancing fuel cell performance. Therefore, we propose a water measurement method combining the X-ray radiography with EIS to investigate the effect of different operating conditions on the growth law and distribution of liquid water in parallel and serpentine flow fields. The attenuation coefficient of liquid water to X-ray is calibrated with constant tube-current and tube-voltage of X-ray generator. Besides, the parallel flow field with hydrophobic treatment is studied. The results show that the water accumulation of the parallel flow field is far more than the serpentine flow field, and the water content of the middle region is higher than that of other regions in the parallel flow field. Furthermore, operating conditions (cathode inlet gas flow rate, inlet gas humidity, and back pressure) have little effect on the liquid water content of the middle region in the parallel flow field. The polarization curve, EIS result, and X-ray radiography show that the performance and water drainage capacity of the hydrophobic parallel flow field are better than the normal one.

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