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| 1 | A Model Output Machine Learning Method for Grid Temperature Forecasts in the Beijing Area显示文摘In this paper, the model output machine learning (MOML) method is proposed for simulating weather consultation, which can improve the forecast results of numerical weather prediction (NWP). During weather consultation, the forecasters obtain the final results by combining the observations with the NWP results and giving opinions based on their experience. It is obvious that using a suitable post-processing algorithm for simulating weather consultation is an interesting and important topic. MOML is a post-processing method based on machine learning, which matches NWP forecasts against observations through a regression function. By adopting different feature engineering of datasets and training periods, the observational and model data can be processed into the corresponding training set and test set. The MOML regression function uses an existing machine learning algorithm with the processed dataset to revise the output of NWP models combined with the observations, so as to improve the results of weather forecasts. To test the new approach for grid temperature forecasts, the 2-m surface air temperature in the Beijing area from the ECMWF model is used. MOML with different feature engineering is compared against the ECMWF model and modified model output statistics (MOS) method. MOML shows a better numerical performance than the ECMWF model and MOS, especially for winter. The results of MOML with a linear algorithm, running training period, and dataset using spatial interpolation ideas, are better than others when the forecast time is within a few days. The results of MOML with the Random Forest algorithm, year-round training period, and dataset containing surrounding gridpoint information, are better when the forecast time is longer. | Haochen LI Chen YU Jiangjiang XIA Yingchun WANG Jiang ZHU Pingwen ZHANG | 2019 | Advances in Atmospheric Sciences2019，36，10： | 9 |
| 2 | Effect of Exposure to Trace Elements in the Soil on the Prevalence of Neural Tube Defects in a High-Risk Area of China显示文摘Objective Our objective is to build a model that explains the association between the exposure to trace elements in the soil and the risk of neural tube defects. Methods We built a function with different parameters to describe the effects of trace elements on neural tube defects. The association between neural tube defects and trace element levels was transformed into an optimization problem using the maximum likelihood method. Results Tin, lead, nickel, iron, copper, and aluminum had typical layered effects (dosage effects) on the prevalence of neural tube defects. Arsenic, selenium, zinc, strontium, and vanadium had no effect, and molybdenum had one threshold value that affected the prevalence of birth defects. Conclusion As an exploratory research work, our model can be used to determine the direction of the effect of the trace element content of cultivated soil on the risk of neural tube defects, which shows the clues by the dosage effect of their toxicological characteristics. Based on our findings, future biogeochemical research should focus on the direct effects of trace elements on human health. | HUANG Jing WU JiLei LI TieJun SONG XinMing ZHANG BingZi ZHANG PingWen ZHENG XiaoYing | 2011 | Biomedical and Environmental Sciences2011，24，2： | 9 |
| 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 tensor model for liquid crystals on a spherical surface显示文摘Rod-like molecules confned on a spherical surface can organize themselves into nematic liquid crystal phases.This can give rise to novel textures displayed on the surface,which has been observed in experiments.An important theoretical question is how to fnd and predict these textures.Mathematically,a stable confguration of the nematic fluid corresponds to a local minimum in the free energy landscape.By applying Taylor expansion and Bingham approximation to a general molecular model,we obtain a closed-form tensor model,which gives a free energy form that is diferent from the classic Landau-de Gennes model.Based on the tensor model,we implement an efcient numerical algorithm to locate the local minimum of the free energy.Our model successfully predicts the splay,tennis-ball and rectangle textures.Among them,the tennis-ball confguration has the lowest free energy. | CHENG Hong ZHANG PingWen | 2013 | Science China Mathematics2013，56，12： | 2 |
| 5 | The Controllable Design of Catalyst Inks to Enhance PEMFC Performance:A Review显示文摘Typical catalyst inks in proton exchange membrane fuel cells(PEMFCs)are composed of a catalyst,its support,an ionomer and a solvent and are used with solution processing approaches to manufacture conventional catalyst layers(CLs).Because of this,catalyst ink formulation and deposition processes are closely related to CL structure and performance.However,catalyst inks with ideal rheology and optimized electrochemical performances remain lacking in the large-scale application of PEMFCs.To address this,this review will summarize current progress in the formulation,characterization,modeling and deposition of catalyst inks.In addition,this review will highlight recent advancements in catalyst ink materials and discuss corresponding complex interactions.This review will also present various catalyst ink dispersion methods with insights into their stability and introduce the application of small-angle scattering and cryogenic transmission electron microscopy(cryo-TEM)technologies in the characterization of catalyst ink microstructures.Finally,recent studies in the kinetic modeling and deposition of catalyst inks will be analyzed. | Yuqing Guo Fengwen Pan Wenmiao Chen Zhiqiang Ding Daijun Yang Bing Li Pingwen Ming Cunman Zhang | 2021 | Electrochemical Energy Reviews2021，4，1： | 2 |
| 6 | On the Isotropic-Nematic Phase Transition for the Liquid Crystal显示文摘In this paper,we study the isotropic-nematic phase transition for the nematic liquid crystal based on the Landau-de Gennes Q-tensor theory.We justify the limit from the Landau-de Gennes flow to a sharp interface model:in the isotropic region, Q≡0;in the nematic region,the Q-tensor is constrained on the manifolds={s_(+)(n −1/3 I),n∈S^(2)}with s_(+) positive constant,and the evolution of alignment vector field obeys the harmonic map heat flow,while the interface separating the isotropic and nematic regions evolves by the mean curvature flow.This problem can be viewed as a concrete but representative case of the Rubinstein-Sternberg-Keller problem introduced in Rubinstein et al.(SIAM J.Appl.Math.49:116-133,1989;SIAM J.Appl.Math.49:1722-1733,1989). | Mingwen Fei Wei Wang Pingwen Zhang Zhifei Zhang | 2018 | Peking Mathematical Journal2018，1，2： | 1 |
| 7 | REFLECTION/TRANSMISSION CHARACTERISTICS OF A DISCONTINUOUS GALERKIN METHOD FOR MAXWELL'S EQUATIONS IN DISPERSIVE INHOMOGENEOUS MEDIA显示文摘在这篇论文,我们分析传播,高度的思考性质为散麦克斯韦的方程订不连续的 Galerkin 方法,原来由陆等求婚了。[J。Comput。Phys。200 (2004 ) , pp。549-580 ] 。我们学习数字方法的思考和传播性质为直到秒顺序多项式元素,为一个 -- 并且二维的麦克斯韦有矩形的网孔的方程。高顺序精确性被显示出因为思考和传播系数接近材料接口。 | Xia Ji Wei Cai Pingwen Zhang | 2008 | Journal of Computational Mathematics2008，26，3： | 1 |
| 8 | Discretization and index-robust error analysis for constrained high-index saddle dynamics on the high-dimensional sphere显示文摘We develop and analyze numerical discretization to the constrained high-index saddle dynamics,the dynamics searching for the high-index saddle points confined on the high-dimensional unit sphere.Compared with the saddle dynamics without constraints,the constrained high-index saddle dynamics has more complex dynamical forms,and additional operations such as the retraction and vector transport are required due to the constraints,which significantly complicate the numerical scheme and the corresponding numerical analysis.Furthermore,as the existing numerical analysis results usually depend on the index of the saddle points implicitly,the proved numerical accuracy may be reduced if the index is high in many applications,which indicates the lack of robustness with respect to the index.To address these issues,we derive the error estimates for numerical discretization of the constrained high-index saddle dynamics on the high-dimensional sphere and then improve it by providing index-robust error analysis in an averaged norm by adjusting the relaxation parameters.The developed results provide mathematical support for the accuracy of numerical computations. | Lei Zhang Pingwen Zhang Xiangcheng Zheng | 2023 | Science China Mathematics2023，66，10： | 1 |
| 9 | A cellular automaton technique for modelling of a binary dendritic growth with convection显示文摘 | Daming Li Ruo Li Pingwen Zhang | 2006 | Applied Mathematical Modelling2006，，6： | 1 |
| 10 | Preparation and properties of thin epoxy/compressed expanded graphite composite bipolar plates for proton exchange membrane fuel cells显示文摘 | Chao Du Pingwen Ming Ming Hou | 2010 | Power Sources2010，，195： | 1 |
| 11 | A two-fluid model for two-phase flow in PEMFCs 显示文摘 | He Guangli Ming Pingwen Zhao Zongchang | 2007 | Journal of Power Sources2007，163，： | 1 |
| 12 | AC impedance characteristics of a 2kW PEM fuel cell stack under different operating conditions and load changes显示文摘 | Xiqiang Yan Ming Hou Liyan Sun Dong Liang Qiang Shen Hongfei Xu Pingwen Ming Baolian Yi | 2007 | International Journal of Hydrogen Energy2007，，17： | 1 |
| 13 | An algorithm for automatic topology discovery of IP networks显示文摘 | Lin Hwachun Lai Shouchuan Chen Pingwen | 1998 | IEEE International Conference on Communications1998，2，6： | 1 |
| 14 | Analysis of the energy-minimization multiscale model with multiobjective optimization显示文摘Gas-solid two-phase flow is ubiquitous in nature and many engineering fields,such as chemical engineering,energy,and mining.The closure of its hydrodynamic model is difficult owing to the complex multiscale structure of such flow.To address this problem,the energy-minimization multi-scale(EMMS)model introduces a stability condition that presents a compromise of the different dominant mechanisms involved in the systems,each expressed as an extremum tendency.However,in the physical system,each dominant mechanism should be expressed to a certain extent,and this has been formulated as a multiobjective optimization problem according to the EMMS principle generalized from the EMMS model.The mathematical properties and physical meanings of this multiobjective optimization problem have not yet been explored.This paper presents a numerical solution of this multiobjective optimization problem and discusses the correspondence between the solution characteristics and flow regimes in gas-solid fluidization.This suggests that,while the most probable flow structures may correspond to the stable states predicted by the EMMS model,the noninferior solutions are in qualitative agreement with the observable flow structures under corresponding conditions.This demonstrates that both the dominant mechanisms and stability condition proposed for the EMMS model are physically reasonable and consistent,suggesting a general approach of describing complex systems with multiple dominant mechanisms. | Yi Mo Mengjie Du Wei Ge Pingwen Zhang | 2020 | Particuology2020，18，1： | 1 |
| 15 | Preparation and properties of thin epoxy/compressed expanded graphite composite bipolar plates for proton exchange membrane fuel ceils 显示文摘 | Chao Du Ming Pingwen Hou Ming | 2010 | Journal of Power Sources2010，195，3： | 1 |
| 16 | An adaptive mesh redistribution method for nonlinear Hamilton-Jacobi equations in two-and three-dimensions显示文摘 | Tang H Z Tang Tao Zhang Pingwen | | 0，，： | 1 |
| 17 | A Deep Spatio-Temporal Forecasting Model for Multi-Site Weather Prediction Post-Processing显示文摘In this paper, we propose a deep spatio-temporal forecasting model (DeepSTF) for multi-site weather prediction post-processing by using both temporal andspatial information. In our proposed framework, the spatio-temporal information ismodeled by a CNN (convolutional neural network) module and an encoder-decoderstructure with the attention mechanism. The novelty of our work lies in that our modeltakes full account of temporal and spatial characteristics and obtain forecasts of multiple meteorological stations simultaneously by using the same framework. We applythe DeepSTF model to short-term weather prediction at 226 meteorological stations inBeijing. It significantly improves the short-term forecasts compared to other widelyused benchmark models including the Model Output Statistics method. In order toevaluate the uncertainty of the model parameters, we estimate the confidence intervals by bootstrapping. The results show that the prediction accuracy of the DeepSTFmodel has strong stability. Finally, we evaluate the impact of seasonal changes and topographical differences on the accuracy of the model predictions. The results indicatethat our proposed model has high prediction accuracy. | Wenjia Kong Haochen Li Chen Yu Jiangjiang Xia Yanyan Kang Pingwen Zhang | 2022 | Communications in Computational Physics2022，31，1： | 1 |
| 18 | Study on carbon matrix composite bipolar plates with balance of conductivity and flexural strength显示文摘In order to balance the conductivity and flexural strength of graphite composite bipolar plates,the influence of conductive filler on the properties of graphite composite bipolar plate was comprehensively studied by using phenolic resin as binder,natural flake graphite as conductive substrate and functional carbon materials with different structures as auxiliary filler.The results show that the particle size of conductive substrate has an important influence on the conductivity enhancement of auxiliary filler.The influence of conductive particle size on auxiliary filler electrical conductivity improvement was first investigated in this research.The effects of various auxiliary filler concentrations on improving electrical conductivity and flexural strength were then examined.This research has substantial implications for the balance of electrical conductivity and flexural strength of graphite composite bipolar plates. | Junsheng Zheng Yuhang Peng Runlin Fan Jing Chen Zize Zhan Dongmei Yao Pingwen Ming | 2023 | Chinese Chemical Letters2023，34，5： | 1 |
| 19 | Crucial properties of the moment closure model FENE-QE显示文摘 | Han Wang Kun Li Pingwen Zhang | 2007 | Journal of Non-Newtonian Fluid Mechanics2007，，2： | 1 |
| 20 | Well-Posedness for the Dumbbell Model of Polymeric Fluids显示文摘 | Weinan E Tiejun Li Pingwen Zhang | 2004 | Communications in Mathematical Physics2004，，2： | 1 |
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