|
|
|
题名
|
作者
|
年代
|
出处
|
被引量
|
| 1 | An alternating direction algorithm for matrix completion with nonnegative factors显示文摘这份报纸为 nonnegative 矩阵 factorization-and-completion 问题介绍一个算法,它试图发现 nonnegative 低等级的矩阵 X 和 Y 以便产品 XY 接近其元素部分被知道的 nonnegative 数据矩阵 M (到某个精确性) 。这个问题聚集二个存在问题:M 的所有条目被给的(i) nonnegative 矩阵因式分解,并且(ii ) nonnegativity 没被要求的低等级的矩阵结束。由拿 nonnegativity 的优点并且低繁茂,一个人能通常就使用二个性质之一比那些获得优异结果。我们建议基于古典轮流出现方向用一个算法解决非凸的抑制最少平方的问题扩充 Lagrangian 方法。算法和数字模拟结果的初步的集中性质被介绍。为 nonnegative 矩阵因式分解比作一个最近的算法,建议算法生产仅仅关于矩阵条目的一半使用的类似的质量的因式分解。在恢复不完全的灰度和 hyperspectral 图象的任务,建议算法比不利用 nonnegativity 的二个最近的矩阵结束算法生产的那些产出全面更好的质量。 | Yangyang XU Wotao YIN Zaiwen WEN Yin ZHANG | 2012 | Frontiers of Mathematics in China2012，7，2： | 23 |
| 2 | A note on semidefinite programming relaxations for polynomial optimization over a single sphere显示文摘We study two instances of polynomial optimization problem over a single sphere. The first problem is to compute the best rank-1 tensor approximation. We show the equivalence between two recent semidefinite relaxations methods. The other one arises from Bose-Einstein condensates(BEC), whose objective function is a summation of a probably nonconvex quadratic function and a quartic term. These two polynomial optimization problems are closely connected since the BEC problem can be viewed as a structured fourth-order best rank-1 tensor approximation. We show that the BEC problem is NP-hard and propose a semidefinite relaxation with both deterministic and randomized rounding procedures. Explicit approximation ratios for these rounding procedures are presented. The performance of these semidefinite relaxations are illustrated on a few preliminary numerical experiments. | HU Jiang JIANG Bo LIU Xin WEN ZaiWen | 2016 | Science China Mathematics2016，59，8： | 7 |
| 3 | Machine Learning−based Weather Support for the 2022 Winter Olympics显示文摘1.A key support for the 2022 Winter Olympics The XXIV Olympic Winter Games are scheduled to take place from 4 to 22 February 2022,followed by the Paralympic Games from 4 to 13 March,in Beijing and towns in the neighboring Hebei Province,China.Weather plays an extremely important role in the outcome of the games(Chen et al.,2018).It can not only cause a difference between a medal or not,but affect the safety of athletes.Success of the Winter Olympics will greatly depend on weather conditions at the outdoor competition venues,dealing with many weather elements including the snow surface temperature,apparent temperature,gust wind speed,snow,visibility,etc.To ensure that the scheduled games go smoothly,it is imperative to have hourly or even every 10-minutely forecasts as well as updated weather-related risk assessments at the venues for the next 240 hours.So far,the Beijing/Hebei Meteorological Observatory has already started intelligent weather forecasting at 3-km resolution based on the results of numerical weather prediction(NWP)models.However,these experiments have suggested that the current forecasting techniques are incapable of capturing the complex mountain weather variations around some venues.The forecasting capability of NWP is constrained partly by limited knowledge of the local weather mechanisms. | Jiangjiang XIA Haochen LI Yanyan KANG Chen YU Lei JI Lve WU Xiao LOU Guangxiang ZHU Zaiwen Wang Zhongwei YAN Lizhi WANG Jiang ZHU Pingwen ZHANG Min CHEN Yingxin ZHANG Lihao GAO Jiarui HAN | 2020 | Advances in Atmospheric Sciences2020，37，9： | 6 |
| 4 | A new trust region algorithm for image restoration显示文摘The image restoration problems play an important role in remote sensing and astronomical image analysis. One common method for the recovery of a true image from corrupted or blurred image is the least squares error (LSE) method. But the LSE method is unstable in practical applications. A popular way to overcome instability is the Tikhonov regularization. However, difficulties will encounter when adjusting the so-called regularization parameter α. Moreover, how to truncate the iteration at appropriate steps is also challenging. In this paper we use the trust region method to deal with the image restoration problem, meanwhile, the trust region subproblem is solved by the truncated Lanczos method and the preconditioned truncated Lanczos method. We also develop a fast algorithm for evaluating the Kronecker matrix-vector product when the matrix is banded. The trust region method is very stable and robust, and it has the nice property of updating the trust region automatically. This releases us from tedious finding the regularization parameters and truncation levels. Some numerical tests on remotely sensed images are given to show that the trust region method is promising. | WEN Zaiwen & WANG Yanfei State Key Laboratory of Scientific Engineering Computing, Institute of Computational Mathematics and Scientific/Engineering Computing, Academy of Mathematics and System Sciences, Chinese Academy of Sciences, Beijing 100080, China National Key Laboratory on Remote Sensing Science, Institute of Remote Sensing Applications, Chinese Academy of Sciences, Beijing 100101, China | 2005 | Science China Mathematics2005，48，2： | 3 |
| 5 | A modified active disturbance rejection control for a wastewater treatment process显示文摘Waste water treatment process(WWTP)control has been attracting more and more attention.However,various undesired factors,such as disturbance,uncertainties,and strong nonlinear couplings,propose big challenges to the control of a WWTP.In order to improve the control performance of the closed-loop system and guarantee the discharge requirements of the effluent quality,rather than take the model dependent control approaches,an active disturbance rejection control(ADRC)is utilized.Based on the control signal and system output,a phase optimized ADRC(POADRC)is designed to control the dissolved oxygen and nitrate concentration in a WWTP.The phase advantage of the phase optimized extended state observer(POESO),convergence of the POESO,and stability of the closed-loop system are analyzed from the theoretical point of view.Finally,a commonly accepted benchmark simulation model no.1.(BSM1)is utilized to test the POESO and POADRC.Linear active disturbance rejection control(LADRC)and the suggested proportion-integration(PI)control are taken to make a comparative research.Both system responses and performance index values confirm the advantage of the POADRC over the LADRC and the suggested PI control.Numerical results show that,as a result of the leading phase of the total disturbance estimation,the POESO based POADRC is an effective and promising way to control the dissolved oxygen and nitrate concentration so as to ensure the effluent quality of a WWTP. | Wei Wei Pengfei Xia Zaiwen Liu Min Zuo | 2020 | Chinese Journal of Chemical Engineering2020，28，10： | 3 |
| 6 | Neutrophil extracellular traps contribute to myofibroblast differentiation and scar hyperplasia through the Toll-like receptor 9/nuclear factor Kappa-B/interleukin-6 pathway显示文摘Background:Inflammation is an important factor in pathological scarring.The role of neutrophils,one of the most important inflammatory cells,in scar hyperplasia remains unclear.The purpose of this article is to study the correlation between neutrophil extracellular traps(NETs)and scar hyperplasia and identify a new target for inhibiting scar hyperplasia.Methods:Neutrophils were isolated from human peripheral blood by magnetic-bead sorting.NETs in plasma and scars were detected by enzyme-linked immunosorbent assays(ELISAs),immunofluorescence and flow cytometry.Immunohistochemistry was used to assess neutrophil(CD66B)infiltration in hypertrophic scars.To observe the entry of NETs into fibroblasts we used immunofluorescence and flow cytometry.Results:We found that peripheral blood neutrophils in patients with hypertrophic scars were more likely to form NETs(p<0.05).Hypertrophic scars showed greater infiltration with neutrophils and NETs(p<0.05).NETs activate fibroblasts in vitro to promote their differentiation and migration.Inhibition of NETs with cytochalasin in wounds reduced the hyperplasia of scars in mice.We induced neutrophils to generate NETs with different stimuli in vitro and detected the proteins carried by NETs.We did not find an increase in the expression of common scarring factors[interleukin(IL)-17 and transforming growth factor-β(TGF-β),p>0.05].However,inhibiting the production of NETs or degrading DNA reduced the differentiation of fibroblasts intomyofibroblasts.In vitro,NETs were found to be mediated by Toll-like receptor 9(TLR-9)in fibroblasts and further phosphorylated nuclear factor Kappa-B(NF-κB).We found that IL-6,which is downstream of NF-κB,was increased in fibroblasts.Additionally,IL-6 uses autocrine and paracrine signaling to promote differentiation and secretion.Conclusions:Our experiments found that NETs activate fibroblasts through the TLR-9/NF-κB/IL-6 pathway,thereby providing a new target for regulating hypertrophic scars. | Yiming Shao Zaiwen Guo Yunxi Yang Lu Liu Jiamin Huang Yi Chen Linbin Li Bingwei Sun | 2022 | Burns & Trauma2022，10，1： | 2 |
| 7 | Time Series Forcasting Based on Judicatuure De-Noising and Multi-algorithms显示文摘 | Xu Jiping Li Hualai Liu Zaiwen | 2011 | Journal of Computational Information Systems2011，7，1： | 1 |
| 8 | Thermal properties and DNA-binding studies of a new kind of acyl hydrazone compounds containing imidazole ring显示文摘 | Jingwen Ren Xiangrong Liu Zaiwen Yang Shunsheng Zhao | 2014 | Thermochimica Acta2014，，： | 1 |
| 9 | High dimensional covariance matrix estimation using multi-factor models from incomplete information显示文摘Covariance matrix plays an important role in risk management, asset pricing, and portfolio allocation. Covariance matrix estimation becomes challenging when the dimensionality is comparable or much larger than the sample size. A widely used approach for reducing dimensionality is based on multi-factor models. Although it has been well studied and quite successful in many applications, the quality of the estimated covariance matrix is often degraded due to a nontrivial amount of missing data in the factor matrix for both technical and cost reasons. Since the factor matrix is only approximately low rank or even has full rank, existing matrix completion algorithms are not applicable. We consider a new matrix completion paradigm using the factor models directly and apply the alternating direction method of multipliers for the recovery. Numerical experiments show that the nuclear-norm matrix completion approaches are not suitable but our proposed models and algorithms are promising. | XU FangFang HUANG JianChao WEN ZaiWen | 2015 | Science China Mathematics2015，58，4： | 1 |
| 10 | How Much Can AI Techniques Improve Surface Air Temperature Forecast?——A Report from AI Challenger 2018 Global Weather Forecast Contest显示文摘In August 2018, the Institute of Urban Meteorology(IUM) in Beijing co-organized with Sinovation Ventures a Weather Forecasting Contest(WFC)—one of the AI(artificial intelligence) Challenger Global Contests. The WFC aims to take advantage of the AI techniques to improve the quality of weather forecast. Across the world, more than1000 teams enrolled in the WFC and about 250 teams completed real-time weather forecasts, among which top 5 teams were awarded in the final contest. The contest results show that the AI-based ensemble models exhibited improved skill for forecasts of surface air temperature and relative humidity at 2-m and wind speed at 10-m height.Compared to the IUM operational analog ensemble weather model forecast, the most notable improvements of 24.2%and 17.0% in forecast accuracy for surface 2-m air temperature are achieved by two teams using the AI techniques of time series model, gradient boosting tree, depth probability prediction, and so on. Meanwhile, it is found that reasonable data processing techniques and model composite structure are also important for obtaining better forecasts. | Lei JI Zaiwen WANG Min CHEN Shuiyong FAN Yingchun WANG Zhiyuan SHEN | 2019 | Journal of Meteorological Research2019，33，5： | 1 |
| 11 | Time series forecasting basedon judicature de-noising and multi-algorithms显示文摘 | Jiping XU Hualai LI Zaiwen LIU | 2011 | Journal ofComputational Information Systems2011，7，1： | 1 |
| 12 | Inteffacial adhesion of plasma treated carbon fiber/ Poly ( phthalazinone ether sulfone ketone) composite 显示文摘 | Chun Lu Ping Chen Qi Yu Zhenfeng Ding Zaiwen Lin Wei Li | 2007 | Journal of Applied Polymer Science2007，，： | 1 |
| 13 | Intelligent information system design on water quality monitoring, water bloom prediction and e- mergency treatment decision - making显示文摘 | Chen Chen Wang Xiaoyi Liu Zaiwen Zhao Zhiyao Wang Xiaokai | 2012 | Applied Me- chanics and Materials( Measuring Technology and Mecha- tronics Automation IV)2012，12，8129： | 1 |
| 14 | Researches of water bloom emergency management decision - making method and system based on fuzzy multiple attribute decision making显示文摘 | Liu Zaiwen Li Lin Wang Xiaoyi Chen Chen | 2012 | International Journal of Computer Science Issues2012，9，： | 1 |
| 15 | Joint Bandwidth Allocation and Path Selection in WANs with Path Cardinality Constraints显示文摘In this paper,we study the joint bandwidth allocation and path selection problem,which is an extension of the well-known network utility maximization(NUM)problem,via solving a multi-objective minimization problem under path cardinality constraints.Specifically,such a problem formulation captures various types of objectives including proportional fairness,average delay,as well as load balancing.In addition,in order to handle the'unsplittable flows',path cardinality constraints are added,making the resulting optimization problem quite challenging to solve due to intrinsic nonsmoothness and nonconvexity.Almost all existing works deal with such a problem using relaxation techniques to transform it into a convex optimization problem.However,we provide a novel solution framework based on the linearized alternating direction method of multipliers(LADMM)to split the original problem with coupling terms into several subproblems.We then derive that these subproblems,albeit nonconvex nonsmooth,are actually simple to solve and easy to implement,which can be of independent interest.Under some mild assumptions,we prove that any limiting point of the generated sequence of the proposed algorithm is a stationary point.Numerical simulations are performed to demonstrate the advantages of our proposed algorithm compared with various baselines. | Jinxin Wang Fan Zhang Zhonglin Xie Zaiwen Wen Gong Zhang | 2021 | Journal of Communications and Information Networks2021，6，3： | 0 |
| 16 | A STOCHASTIC TRUST-REGION FRAMEWORK FOR POLICY OPTIMIZATION显示文摘In this paper,we study a few challenging theoretical and numerical issues on the well known trust region policy optimization for deep reinforcement learning.The goal is to find a policy that maximizes the total expected reward when the agent acts according to the policy.The trust region subproblem is constructed with a surrogate function coherent to the total expected reward and a general distance constraint around the latest policy.We solve the subproblem using a preconditioned stochastic gradient method with a line search scheme to ensure that each step promotes the model function and stays in the trust region.To overcome the bias caused by sampling to the function estimations under the random settings,we add the empirical standard deviation of the total expected reward to the predicted increase in a ratio in order to update the trust region radius and decide whether the trial point is accepted.Moreover,for a Gaussian policy which is commonly used for continuous action space,the maximization with respect to the mean and covariance is performed separately to control the entropy loss.Our theoretical analysis shows that the deterministic version of the proposed algorithm tends to generate a monotonic improvement of the total expected reward and the global convergence is guaranteed under moderate assumptions.Comparisons with the state-of-the–art methods demonstrate the effectiveness and robustness of our method over robotic controls and game playings from OpenAI Gym. | Mingming Zhao Yongfeng Li Zaiwen Wen | 2022 | Journal of Computational Mathematics2022，40，6： | 0 |
| 17 | A TRUST-REGION METHOD FOR NONSMOOTH NONCONVEX OPTIMIZATION显示文摘We propose a trust-region type method for a class of nonsmooth nonconvex optimization problems where the objective function is a summation of a(probably nonconvex)smooth function and a(probably nonsmooth)convex function.The model function of our trust-region subproblem is always quadratic and the linear term of the model is generated using abstract descent directions.Therefore,the trust-region subproblems can be easily constructed as well as efficiently solved by cheap and standard methods.When the accuracy of the model function at the solution of the subproblem is not sufficient,we add a safeguard on the stepsizes for improving the accuracy.For a class of functions that can be“truncated”,an additional truncation step is defined and a stepsize modification strategy is designed.The overall scheme converges globally and we establish fast local convergence under suitable assumptions.In particular,using a connection with a smooth Riemannian trust-region method,we prove local quadratic convergence for partly smooth functions under a strict complementary condition.Preliminary numerical results on a family of Ei-optimization problems are reported and demonstrate the eficiency of our approach. | Ziang Chen Andre Milzarek Zaiwen Wen | 2023 | Journal of Computational Mathematics2023，41，4： | 0 |
| 18 | Preface显示文摘In the past several centuries,there have been two major different paradigms for doing scientific research:the Keplerian paradigm and the Newtonian paradigm.In the Keplerian paradigm,natural laws are discovered through the analysis of data while in the Newtonian paradigm,one focuses on pursuing fundamental principles that govern Nature. | Weinan E Princeton Falai Chen Zaiwen Wen | 2023 | Communications in Mathematics and Statistics2023，11，1： | 0 |
| 19 | On the local convergence of a stochastic semismooth Newton method for nonsmooth nonconvex optimization显示文摘In this work,we present probabilistic local convergence results for a stochastic semismooth Newton method for a class of stochastic composite optimization problems involving the sum of smooth nonconvex and nonsmooth convex terms in the objective function.We assume that the gradient and Hessian information of the smooth part of the objective function can only be approximated and accessed via calling stochastic firstand second-order oracles.The approach combines stochastic semismooth Newton steps,stochastic proximal gradient steps and a globalization strategy based on growth conditions.We present tail bounds and matrix concentration inequalities for the stochastic oracles that can be utilized to control the approximation errors via appropriately adjusting or increasing the sampling rates.Under standard local assumptions,we prove that the proposed algorithm locally turns into a pure stochastic semismooth Newton method and converges r-linearly or r-superlinearly with high probability. | Andre Milzarek Xiantao Xiao Zaiwen Wen Michael Ulbrich | 2022 | Science China Mathematics2022，65，10： | 0 |
| 20 | LINEARLY CONVERGENT FIRST-ORDER ALGORITHMS FOR SEMIDEFINITE PROGRAMMING显示文摘在这份报纸,我们认为二是不同明确的表达(一个人是光滑的,另一个是 nonsmooth ) 为解决线性矩阵不平等(LMI ) , semidefinite 编程(SDP ) 的一个重要的班,在某个 Slater 限制资格假设下面。我们然后建议二个一阶的方法,一个基于他们线性地集成为的 Nesterovs 最佳的方法,和表演基于 subgradient 方法和其它解决这些明确的表达。而且,我们介绍没有要求任何问题参数的输入,为光滑、非光滑的问题一致地线性地收敛的一个加速的 prox 水平方法。最后,我们考虑 LMI 的一种特殊情况,即,一个线性地会聚的算法能在一个弱得多的假设下面被获得的不平等和表演的线性系统。 | Cong D. Dang Guanghui Lan Zaiwen Wen | 2017 | Journal of Computational Mathematics2017，35，4： | 0 |
您所在的机构暂未开通此部分的功能，请联系管理员