高光谱遥感反演土壤重金属含量研究进展

土壤重金属污染是当今重要的世界性环境问题之一。如何快速高效地获取土壤重金属含量及分布信息是进行污染风险评价及预测研究的前提。高光谱遥感具有无损、实时获取信息的优势,利用高光谱技术反演土壤重金属含量仍处于探讨阶段,对其反演机理和建模方法的研究成果进行了介绍和分析。认为充分研究不同类型土壤对重金属的吸附特性,是深入理解重金属含量反演机理的基础。加强不同土壤类型、不同污染程度的案例对比分析,发展光谱信号处理方法,引入非线性建模算法,构建重金属形态量反演模型,是土壤重金属含量遥感估算研究的重要研究方向。     

Enhancing social media competitiveness of small businesses: insights from small pizzerias

Social media provide an online platform for enterprises to engage existing customers and attract new customers. Although social media can be easily set up at no cost, however, due to limited human and financial resources, many small businesses find it challenging to compete against large enterprises in social media use. While more and more small businesses have jumped on the bandwagon of social media in recent years, few studies investigated the social media strategies that can help small businesses to survive and even thrive against large competitors in the social media arena. Therefore, we studied 32 small pizzerias in a mid-size U.S. city in terms of their social media use for business. Our study found that small pizzerias emphasizing social media use on community relations and social responsibility tend to be more successful in attracting and engaging local customers. This study also sheds light on both effective strategies and successful practices of social media use by small pizzerias. The insights and recommendations identified from this study can help small businesses to enhance their social media competitiveness against large enterprises.     

饮用水深度处理工艺活性炭运行生命周期探讨

通过试验和对生产性活性炭池运行情况的调查分析,对臭氧-活性炭饮用水深度处理工艺中活性炭去除有机物的规律、活性炭使用寿命(生命周期)的影响因素及评判指标进行了探讨,并对机理进行了分析.活性炭吸附期和使用寿命与进水水质、臭氧投加量、炭池滤速及出水要求等因素有关,臭氧氧化主要是通过提高进水可降解有机碳与总有机碳的比值,起到延长生物活性炭运行寿命的作用,活性炭的吸附参数不能作为活性炭生命周期的唯一判定指标,出水水质限值是控制活性炭生命周期时间点的最重要参数.     

机载火控系统通用测试平台设计与实现

机载火控系统种类繁多,设备日益复杂且不断更新,对机载火控系统检测系统的开发速度和更新速度提出了更高的要求,通用测试平台能够实现测试设备的快速开发和同步更新,满足机务部队快速保障的需求;介绍了基于虚拟仪器技术和PC104总线的硬件通用平台的设计方法和基于测试模型的软件通用平台的设计方法;实践证明,该机载火控系统通用测试平台能够实现测试系统的快速开发和更新,且环境适应能力强,运行可靠,使用方便。     

Spin dynamics and implications for superconductivity: some problems with thed-wave scenario

We review the spin dynamics of the normal state of the cuprates with special emphasis on neutron data in both the YBa₂Cu₃O_7– and La_2–x Sr _x CuO₄ systems. When realistic models of the Fermi surface shapes are incorporated, along with a moderate degree of spin fluctuations, we find good semiquantitative agreement with experiment for both cuprates. Building on the success of this Fermi-liquid-based scheme, we explore the implications ford-wave pairing from a number of vantage points. We conclude that our present experimental and theoretical understanding is inadequate to confirm or refute thed-wave scenario.     

A converter-assisting flexible switch topology and its control strategy北大核心

The rapid development of new energy in the distribution network increases its flexibility while making it more complicated to operate and manage the network. For this reason, a novel flexible switch, which is composed of integrated gate- commutated thyristors (IGCT) and parallel voltage converters, is proposed in this paper. Applying virtual synchronous generator (VSG) control on the parallel voltage converterensures smoothness and steadiness while switching from one feeder to another. Firstly, the proposed flexible switch is compared with the flexible multi-state switch and the mechanical switch on their main characteristics. Then, the operating features of the flexible switch before, during, and after feeder fault are analyzed, as well as its switching logic. Finally, the switching process between different feeders is simulated on a control in-the-loop experiment based on RT-Lab. The voltage and current waveforms are obtained under different operating modes and during flexible switching. The experiment resultsshow that the flexible switch has short-term voltage support capability and does not generate voltage and current impulses during the switching process. © 2023, Editorial Department of Electric Power Engineering Technology. All rights reserved.     

Current trajectory image-based protection algorithm for transmission lines connected to MMC-HVDC stations using CA-CNN

In the presence of an MMC-HVDC system, current differential protection (CDP) has the risk of failure in operation under an internal fault. In addition, CDP may also incur security issues in the presence of current transformer (CT) saturation and outliers. In this paper, a current trajectory image-based protection algorithm is proposed for AC lines connected to MMC-HVDC stations using a convolution neural network improved by a channel attention mechanism (CA-CNN). Taking the dual differential currents as two-dimensional coordinates of the moving point, the moving-point trajectories formed by differential currents have significant differences under internal and external faults. Therefore, internal faults can be identified using image recognition based on CA-CNN. This is improved by a channel attention mechanism, data augmentation, and adaptive learning rate. In comparison with other machine learning algorithms, the feature extraction ability and accuracy of CA-CNN are greatly improved. Various fault conditions like different network structures, operation modes, fault resistances, outliers, and current transformer saturation, are fully considered to verify the superiority of the proposed protection algorithm. The results confirm that the proposed current trajectory image-based protection algorithm has strong learning and generalizability, and can identify internal faults reliably.     

Catheter‐related fungal endocarditis caused by Candida parapsilosis in a hemodialysis patient

Fungal endocarditis (FE) is commonly regarded as a rare but fatal disease. The incidence of infective endocarditis (IE) in hemodialysis (HD) patients is thought to be obviously higher than that in the general population. Moreover, IE occurs more likely in HD patients with catheters. With the increase of HD population and extensive use of catheters in HD patients, FE, as a special form of IE, may increase and bring new challenges to clinicians. We reported a case of FE associated with catheter infection in a 44‐year‐old woman on HD. The risk factors and treatment strategies of FE in HD patients were discussed.     

BeehiveZ:一个开放的业务过程模型管理框架

随着面向服务架构、业务过程管理技术的推广应用,企业中用建模语言描述的业务过程模型越来越多,这些模型描述了企业核心的业务逻辑,是企业最宝贵的知识资产.为了更好地促进企业的发展,提升竞争力,需要将这些业务过程模型作为数据进行有效地管理、建立企业过程模型库,并支持对过程模型的存储、浏览、相似性度量、检索等操作和应用开发.提出了一个开放的业务过程模型管理框架--BeeHiveZ,阐述了BeeHiveZ的体系结构、关键技术及系统功能与操作等内容.BeeHiveZ现已在开源软件社区SourceForge. net上发布.     

Model Transduction for Triangle Meshes

This paper proposes a novel method, called model transduction, to directly transfer pose between different meshes, without the need of building the skeleton configurations for meshes. Different from previous retargetting methods, such as deformation transfer, model transduction does not require a reference source mesh to obtain the source deformation, thus effectively avoids unsatisfying results when the source and target have different reference poses. Moreover, we show other two applications of the model ...