PROJECTED GRADIENT DESCENT BASED ON SOFT THRESHOLDING IN MATRIX COMPLETION

Matrix completion is the extension of compressed sensing.In compressed sensing,we solve the underdetermined equations using sparsity prior of the unknown signals.However,in matrix completion,we solve the underdetermined equations based on sparsity prior in singular values set of the unknown matrix,which also calls low-rank prior of the unknown matrix.This paper firstly introduces basic concept of matrix completion,analyses the matrix suitably used in matrix completion,and shows that such matrix should satisfy two conditions:low rank and incoherence property.Then the paper provides three reconstruction algorithms commonly used in matrix completion:singular value thresholding algorithm,singular value projection,and atomic decomposition for minimum rank approximation,puts forward their shortcoming to know the rank of original matrix.The Projected Gradient Descent based on Soft Thresholding(STPGD),proposed in this paper predicts the rank of unknown matrix using soft thresholding,and iteratives based on projected gradient descent,thus it could estimate the rank of unknown matrix exactly with low computational complexity,this is verified by numerical experiments.We also analyze the convergence and computational complexity of the STPGD algorithm,point out this algorithm is guaranteed to converge,and analyse the number of iterations needed to reach reconstruction error.Compared the computational complexity of the STPGD algorithm to other algorithms,we draw the conclusion that the STPGD algorithm not only reduces the computational complexity,but also improves the precision of the reconstruction solution.

A new analytical algorithm for computing probability distribution of project completion time

An analytical algorithm was presented for the exact computation of the probability distribution of the project completion time in stochastic networks,where the activity durations are mutually independent and continuously distributed random variables. Firstly,stochastic activity networks were modeled as continuous-time Markov process with a single absorbing state by the well-know method of supplementary variables and the time changed from the initial state to absorbing state is equal to the project completion time.Then,the Markov process was regarded as a special case of Markov skeleton process.By taking advantage of the backward equations of Markov skeleton processes,a backward algorithm was proposed to compute the probability distribution of the project completion time.Finally,a numerical example was solved to demonstrate the performance of the proposed methodology.The results show that the proposed algorithm is capable of computing the exact distribution function of the project completion time,and the expectation and variance are obtained.

Emerging Challenges in the Completion of Construction Projects through Public Private Partnerships: Empirical Literature Review

The process of engaging private sector in the provision of public infrastructure can improve economic value in service delivery and enable the government to utilize the capabilities and expertise held by private sector. This has a positive impact on the public in terms of improving their well-being. This literature review attempts to compare the challenges encountered in implementation of PPP projects across the world, with a view to determining cross cutting challenges and recommendations for developing countries. A literature review was conducted for empirical studies focusing on construction projects. The studies are reviewed by analyzing the methodology used and conclusions made to identify the geographical study area, Public Private Partnership project financing model, emerging challenges and recommendation for future project management. The literature search was based on four keywords: construction projects, completion of construction projects, public private partnership, challenges in construction projects. Thus, a total of 11 empirical studies were identified for review in Europe, Asia and Africa. The review revealed that most risk factors affecting project completion can be categorized as human and organizational factors and unknown geotechnical conditions that were not known beforehand. Specifically, project owners’ interference was also attributable to delays with the delays having significant implications for project execution. Risks have great impact on the performance of construction projects because they affect their quality, time and cost. The general remedy to such potential risk factors is adoption of reliable prediction mechanisms which would estimate those factors using a probabilistic model that does not rely on expert judgments as they tend to be unreliable.

A Successful Scientific Cooperation——Smooth Completion of a Sino-Japanese Joint Research Project of Well-off Household Residences.

On February 24, 1993, when the appraisal meeting of the Sino-Japanese Joint Research Project of Well-off Household Residences was held in Beijing, Person-in-charge from the China Building Technology Development and Research Centre and the Japan International Cooperation Undertakings Group signed the project appraisal report. It marked the successful completion of this three-year joint research project.

Successful Completion of AI-Ahmadi Refinery Restoration Project in Kuwait

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Shanghai 500-kV Jing’an transmission & substation project completed

On April 16, the 500-kV Jing’an transmission & substation project in Shanghai, a super-large, multi-voltage level, all-underground, full digital intelligent substation, was completed and put into operation,

Expansion Project Completed at Yangtze Petrochemical Company

Renovation of the 650,000-ton ethylene unit was wound up at Yangtze Petrochemical Company Limited on July 26, which draws an investment of 4.352 billion yuan. The renovation project boosts the annual ethylene production capacity of Yangtze Company to 650,000 tons from 400,000 tons, the polyethylene and polypropylene capacity to 400,000 tons from 200,000 tons, the butadiene capacity to 200,000 tons from 100,000 tons and the gasoline hydrorefining capacity to 500,000 tons from 300,000 tons.

First phase project of Huaneng Yingkou Cogeneration Plant completed

On December 2, 2009, Unit 1 of Huaneng Yingkou Cogeneration Plant smoothly passed 168-hour triaoperation. 11 days later, Unit 2 also successfully passed the trial operation. The project

稀疏阵列的鲁棒矩阵填充DOA估计算法

稀疏阵列布阵灵活,增大阵列孔径的同时还能减少阵元间耦合,但基于稀疏阵列的传统波达方向估计会导致角度模糊混叠,带来估计精度差和稳健性不足的问题。针对以上问题,提出一种适用于稀疏阵列波达方向估计的加权截断奇异值投影(weighted truncated singular value projection,WT-SVP)的鲁棒矩阵填充算法。在填充迭代过程中根据奇异值的大小分配权重,突出大奇异值包含的阵列信息,减少小奇异值中不必要的噪声信息,从而优化传统奇异值投影算法。该算法可以实现稀疏阵列的孔洞信息恢复,对不连续阵元充分利用,同时WT-SVP填充算法实现了稀疏阵列波达方向估计的高精度、高分辨以及在低信噪比、低快拍时的高鲁棒性。

2018-2022年国家自然科学基金医学免疫学领域结题项目情况分析

目的分析2018-2022年国家自然科学基金(National Natural Science Foundation of China,NSFC)医学免疫学领域结题项目,探讨该领域的发展现状及存在的问题,为未来项目申请和优化资金导向提供参考。方法以科学基金共享服务网作为数据来源,获取2018-2022年NSFC医学免疫学领域已结题项目的项目名称、项目类别、资助经费、分支学科代码、依托单位、项目关键词、研究成果等信息,并借助Microsoft Excel 2021、CiteSpace 6.1.R6和VOSviewer 1.6.18软件进行可视化分析。结果2018-2022年NSFC医学免疫学领域结题项目共1206项,资助经费60154.5万元,来自30个省、市和自治区,其中57.88%的项目集中在上海(191项)、北京(184项)、江苏(136项)、广东(127项)、山东(60项),南方地区的结题数量是北方地区的2.43倍;所有项目分属160家依托单位,主要集中在综合类大学,其中上海交通大学以64项的结题量排名第一;研究成果主要体现在期刊论文(7481篇)、人才培养(1748人)和专利(授权269项)三个方面;分支学科主要集中在H1104(炎症、感染与免疫)和H1107(自身免疫性疾病),其中类风湿关节炎(rheumatoid arthritis,RA)和系统性红斑狼疮(systemic lupus erythematosus,SLE)是该研究领域的热点疾病,巨噬细胞是热点细胞。结论2018-2022年,NSFC医学免疫学领域结题项目在地域、依托单位、研究成果类别和分支学科之间存在明显差异,研究热点主要集中在免疫调节和自身免疫性疾病。

高反光物体的局部点云孔洞补全方法

针对高反光物体点云数据存在噪声明显、孔洞过大,使用传统贪婪投影三角化算法无法达到点云补全目的的问题,提出一种改进的贪婪三角化点云补全算法。利用统计滤波和高斯滤波进行离群点去除和平滑处理;采用移动最小二乘法对局部点云进行上采样增强数据,并且对点云进行进一步平滑。将贪婪三角化算法中的kd树(k-dimensional tree)算法替换为效率更高的八叉树(octree)搜索算法,将主成分分析法替换为准确率更高的移动最小二乘法进行法线估计;最后,进行点云三角化,完成点云补全。实验结果表明,改进算法能够更好地补全孔洞,补全后表面更加平滑、结构更为准确,且花费时间更短。

政府投资项目竣工结算争议诱发因素研究

竣工结算是确定建设项目工程造价的重要环节。经财政投资评审机构评审的竣工结算是工程尾款拨付的重要依据。在竣工结算环节,财政投资评审机构、建设单位、施工单位会产生许多纷争,这些纷争具有多样性和不确定性,对竣工结算的质效有很大的影响。本文以广州空港经济区政府投资项目为研究对象,通过案例分析、专家访谈、构建DEMATEL模型等方法,对政府投资项目竣工结算争议诱发因素进行识别和分析,得出诱发争议的关键因素。针对关键影响因素,基于建设单位视角,提出减少竣工结算争议发生的建议,以期为顺利推进竣工结算、提高竣工结算质效提供参考。

环境污染与健康课程思政创新实践

为实现教学与育人相统一,积极构建专业课程与思想政治理论、综合素养“三位一体”的思想政治教育教学体系,全国高校正积极开展思政教学改革。环境污染与健康课程从人类健康实际问题出发,兼具环境类课程思政特色。本课程在教学中采用“项目式教学”,引导学生主动思考交流、积极参与课堂互动、开拓创新思维、增强实践动手能力,教导学生学以致用。最终实现习近平新时代中国特色社会主义思想在环境污染与健康课程中的渗透,培养德才兼备的高素质人才。