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Using orbital sensitivity analysis to pinpoint the role of orbital interactions in thermoelectric power factor

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npj Computational Materials 2023年第1期9卷 937-945页

作者： wenhao zhang Jean-François Halet Takao Mori WPI Center for Materials Nanoarchitectonics(MANA) National Institute for Materials ScienceTsukubaJapan Graduate School of Pure and Applied Sciences University of TsukubaTsukubaJapan CNRS-Saint-Gobain-NIMS Laboratory for Innovative Key Materials and Structures(LINK)National Institute for Materials ScienceTsukubaJapan

The modification of the electronic band structure is of critical importance for thermoelectric materials whose heat to electricity power generation is related to carrier effective mass and alignment of semiconductor band *** approach to optimize the electronic band structure is by modification of orbital interactions through doping or *** the current ab-initio quantum chemical calculations can help us to investigate orbital components of electronic bands,they reveal little information on the relative tunability of electronic states and transport properties with respect to orbital *** this work,we present a method,based on a symmetry-adapted tight-binding model and sensitivity analysis,that can pinpoint the role of orbital interactions in determining electronic band structure and transport *** an application,a systematic theoretical analysis is used to show how the power factor of PbTe can/cannot be improved by playing with interatomic orbital *** orbital interaction sensitivity analysis introduced in this work can easily be applied to other compounds or properties.

关键词： properties orbital symmetry

Underoil superhydrophilic flame-retardant 3D porous composite for efficient on-demand emulsion separation:Interface engineering design on sphagnum moss

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Friction 2024年第10期12卷 2222-2240页

作者： Yuyan GUO Peng LIU wenhao zhang Zhiguang GUO Weimin LIU Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials Hubei UniversityWuhan 430062China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou730000China

Oil pollution and the energy crisis make oil-water separation an urgent for human *** widespread use of materials with a single emulsion separation capability is *** on-demand separation materials can adapt to a wide range of application scenarios,thus having a wider range of *** underoil superhydrophilic surface is of great significance for realizing the on-demand separation of oil/water emulsions through the removal of water in the oil and oil in the water.A 3D porous emulsion separation material based on the superhydrophilic principle of sphagnum moss was *** material was prepared in a simple step by taking advantage of the adhesion of polydopamine and the introduction of the as-prepared superhydrophilic BaSO4 nanoparticles to achieve superhydrophilicity with a water contact angle(WCA)of 0°and an oil contact angle(OCA)of 157.3°,resulting in excellent separation performance for both water-in-oil and oil-in-water *** superhydrophilic porous composite(OSPC)can complete two kinds of emulsion separations by filtration or *** adsorbs water from water-in-oil emulsion to achieve separation,with a good adsorption capacity of 74.38 g/g and efficiency up to 99%.It can also filter oil-in-water emulsions with an efficiency of 99.92%.The separation efficiencies are all almost unchanged after ten separation ***,the material has excellent flame retardancy,which reduces the possibility of secondary *** three-dimensional porous sponge has excellent on-demand separation performance for multiple *** provides a new preparation strategy for underoil superhydrophilic materials and a new idea for the design direction of special wetting materials for the on-demand separation of oil/water emulsions.

关键词： on-demand emulsion separation porous absorption filtration underoil hydrophilicity superwettability

The opportunities and challenges of ionic liquids in perovskite solar cells

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Journal of Energy Chemistry 2023年第2期77卷 157-171,I0005页

作者： Jian Yang Jianfei Hu wenhao zhang Hongwei Han Yonghua Chen Yue Hu Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074HubeiChina Key Laboratory of Flexible Electronics(KLOFE)&Institution of Advanced Materials(IAM) Nanjing Tech University(NanjingTech)30 South Puzhu RoadNanjing 211816JiangsuChina

Metal halide perovskite solar cells(PSCs)have shown great potential to become the next generation of photovoltaic devices due to their simple fabrication techniques,low cost,and soaring power conversion efficiency(PCE).However,mismatched with the quickly updated PCEs,the improvement of device stability is challenging and still remains a critical hurdle in the path to ***,ionic liquids(ILs)have been found to play multiple roles in obtaining efficient and stable *** ILs usually consist of large organic cations and organic or inorganic anions,which have weak electrostatic attraction and are generally liquid at around 100℃.ILs are almost non-volatile,non-flammable,with high ionic conductivity and excellent thermal and electrochemical *** roles of ILs in PSCs vary with their composition,that is,the types of anions and *** this review,we summarize the roles of anions and cations in terms of precursor solutions,additives,perovskite/charge transport layer interface engineering,and charge transport *** article aims to set up a structure–property-stability-performance correlations conferred by the IL in PSC and provide assistance for the anion and cation selection for improving the quality of perovskite film,optimizing interface contact,reducing defect states,and improving charge extraction and transport ***,the application of IL in PSCs is discussed and prospected.

关键词： Perovskite solar cells Ionic liquid Anions and cations Additive Interface engineering

Cyber-Physical Resilience Enhancement for Power Transmission Systems with Energy Storage Systems

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 844-855页

作者： wenhao zhang Dongyang Rui Weihong Wang Yang Guo Zhaoxia Jing Wenhu Tang School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China Guangzhou Zhiguang Electric Co. Ltd and Zhiguang Research Institute(Guangzhou)Co.LtdGuangzhou 510765China

In a power system, when extreme events occur, such as ice storm, large scale blackouts may be unavoidable. Such small probability but high risk events have huge impact on power systems. Most resilience research in power systems only considers faults on the physical side, which would lead to overly idealistic results. This paper proposes a two-stage cyber-physical resilience enhancement method considering energy storage (ES) systems. The first stage calculates optimal planning of ES systems, and the second stage assesses resilience and enhancement of ES systems during the disaster. In the proposed model, cyber faults indirectly damage the system by disabling monitoring and control function of control center. As a result, when detection and response process of physical faults are blocked by cyber failures, serious load shedding occurs. Such a cyber-physical coupling mechanism of fault, response, restoration process is demonstrated in the modified IEEE Reliable Test System-79 (RTS-79). Simulation results show compared with the physical-only system, the cyber-physical system has a more accurate but degraded resilient performance. Besides, ES systems setting at proper place effectively enhance resilience of the cyber-physical transmission system with less load Shedding.

关键词： Cyber-physical faults energy storage systems resilience enhancement transmission systems

绝经后女性体质量指数与内侧单髁置换后疗效的关系

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中国组织工程研究 2025年第21期29卷 4537-4544页

作者：牟利民李超张文豪石正誉邓迎杰方锐新疆医科大学第四临床医学院新疆维吾尔自治区乌鲁木齐市830000 新疆医科大学第六附属医院新疆维吾尔自治区乌鲁木齐市830000 新疆医科大学附属中医医院(新疆维吾尔自治区中医药研究院新疆维吾尔自治区中医医院)新疆维吾尔自治区乌鲁木齐市830000

背景:单髁置换后随访中,部分患者出现膝关节疼痛活动受限,其中绝经后肥胖女性最为多见;体质量指数作为衡量身体肥胖程度的重要指标,是否与单髁置换后疗效有关,肥胖是否会影响术后膝关节功能,值得进一步研究。目的:评价绝经后肥胖女性患... 详细信息

背景:单髁置换后随访中,部分患者出现膝关节疼痛活动受限,其中绝经后肥胖女性最为多见;体质量指数作为衡量身体肥胖程度的重要指标,是否与单髁置换后疗效有关,肥胖是否会影响术后膝关节功能,值得进一步研究。目的:评价绝经后肥胖女性患者行内侧单髁置换后的临床疗效,明确体质量指数对单髁置换后患者生活质量的影响。方法:纳入新疆医科大学第四临床医学院2017年1月至2019年1月因内侧膝关节疼痛并初次行内侧单髁置换的女性绝经患者;根据标准共纳入270例,按照术前体质量指数分为4组:正常组42例(体质量指数18.5-22.9 kg/m^(2)),超重组58例(体质量指数23.0-24.9 kg/m2),肥胖组122例(体质量指数25.0-29.9 kg/m^(2)),重度肥胖组48例(体质量指数≥30 kg/m^(2))。分别比较各组术前、术后及末次随访美国特种外科医院膝关节评分、安大略省西部和麦克马斯特大学骨关节炎指数评分、膝关节活动度、目测类比评分及髋膝踝角;随访并记录患者术后假体使用时间、失效或翻修原因,计算并比较各组假体的有效使用率,采用生存曲线对假体有效使用率进行统计学分析。结果与结论:(1)各组患者间术后随访时间、膝关节活动度、目测类比评分、髋膝踝角比较差异无显著性意义(P>0.05);(2)术后末次随访各组间美国特种外科医院膝关节评分、安大略省西部和麦克马斯特大学骨关节炎指数评分均较术前显著改善(P0.05),其余各组2个时间点之间差异均有显著性意义(P<0.05);(4)正常、超重、肥胖及重度肥胖组假体有效使用率依次为100%,95%,94%和94%,组间比较差异无显著性意义(χ^(2)=2.532,P=0.469);(5)提示绝经后肥胖女性患者体质量指数值对内侧单髁假体有效使用率无显著影响;肥胖是影响患者术后膝关节功能评分及假体有效使用率的重要因素,单髁置换前后应适当控制体质量,同时女性体质量指数≥30 kg/m^(2)不是单髁置换的最佳适应证,建议行单髁置换的女性患者应将体质量指数控制在30 kg/m^(2)以下。

关键词：绝经后女性体质量指数膝骨关节炎单髁置换术雌激素骨质疏松

Unknown system dynamics estimator-based impedance control for lower limb exoskeleton with enhanced performance

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Control Theory and Technology 2024年第1期22卷 56-68页

作者： wenhao zhang Peng Song Mingying Wu Qiang Li Xinmin Mo Pingxin Ji Northwest Institute of Mechanical and Electrical Engineering Xianyang712099ShaanxiChina Xi’an Exo-Smart Dynamics Technology Ltd. Xi’an712046ShaanxiChina Department of Mechanical and Engineering Beijing Institute of TechnologyBeijing100081China

In this article, an unknown system dynamics estimator-based impedance control method is proposed for the lower limb exoskeleton to stimulate the tracking flexibility with the terminal target position when suffering parametric inaccuracies and unexpected disturbances. To reinforce the robust performance, via constructing the filtering operation-based dynamic relation, i.e., invariant manifold, the unknown system dynamics estimators are employed to maintain the accurate perturbation identification in both the hip and knee subsystem. Besides, a funnel control technique is designed to govern the convergence process within a minor overshoot and a higher steady-state precision. Meanwhile, an interactive complaint result can be obtained with the aid of the impedance control, where the prescribed terminal trajectory can be adjusted into the interaction variable-based target position by the force–position mapping, revealing the dynamic influence between the impedance coefficient (stiffness and damping) and the adjusted position magnitude. A sufficient stability analysis verifies the ultimately uniformly bounded results of all the error signals, and even the angle errors can be regulated within the predefined funnel boundary in the whole convergence. Finally, some simulations are provided to demonstrate the validity and superiority including the enhanced interaction flexibility and robustness.

关键词： Trajectory tracking Invariant manifold Funnel control Impedance control Lower limb exoskeleton

Visualizing the charge order and topological defects in an overdoped （Bi,Pb）2Sr2CuO6+x superconductor

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Science China(Physics,Mechanics & Astronomy) 2020年第2期63卷 117-123页

作者： Ying Fei Yuan Zheng KunLiang Bu wenhao zhang Ying Ding XingJiang Zhou Yi Yin Department of Physics Zhejiang UniversityHangzhou 310027China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Collaborative Innovation Center of Quantum Matter Beijing 100871China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China

Electronic charge order is a symmetry breaking state in high-Tc cuprate superconductors. In scanning tunneling microscopy, the detected charge-order-induced modulation is an electronic response of the charge order. For an overdoped(Bi,Pb)2Sr2CuO6+x sample, we apply scanning tunneling microscopy to explore local properties of the charge order. The ordering wavevector is nondispersive with energy, which can be confirmed and determined. By extracting its order-parameter field, we identify dislocations in the stripe structure of the electronic modulation, which correspond to topological defects with an integer winding number of ±1. Through differential conductance maps over a series of reduced energies, the development of different response of the charge order is observed and a spatial evolution of topological defects is detected. The intensity of charge-order-induced modulation increases with energy and reaches its maximum when approaching the pseudogap energy. In this evolution, the topological defects decrease in density and migrate in space. Furthermore, we observe appearance and disappearance of closely spaced pairs of defects as energy changes. Our experimental results could inspire further studies of the charge order in both high-Tccuprate superconductors and other charge density wave materials.

关键词： cuprate superconductors scanning tunneling microscopy charge order topological defects

Unveiling the effect of amino acids on the crystallization pathways of methylammonium lead iodide perovskites

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Journal of Energy Chemistry 2022年第6期31卷 253-260,I0008页

作者： wenhao zhang Jiankang Du Weihua zhang Yanmeng Chu Anyi Mei Yaoguang Rong Xinyu Gao Hongwei Han Yue Hu Michael Grätzel Center for Mesoscopic Solar Cells Wuhan National Laboratory for OptoelectronicsKey Laboratory of Materials Chemistry for Energy Conversion and Storage of Ministry of EducationHuazhong University of Science and TechnologyWuhan 430074HubeiChina Shanghai Synchrotron Radiation Facility(SSRF) Chinese Academy of SciencesShanghai 201204China

Multifunctional additives are widely used to improve crystallization and to passivate defects in perovskite solar cells. The roles of these additives are usually related to the various functional groups contained in such additives. Here, we introduce a serious of analogues of amino acids into methylammonium lead iodide perovskites and find they play different roles in the crystallization process despite the fact that these additives share exactly the same terminal groups, namely one amino group and one carboxyl group. The corresponding crystallization pathways are established for the first time via monitoring the time-resolved phase formation and transformation. We find that avoiding the rapid formation of perovskites from precursor solution can facilitate the uniform nucleation and growth of perovskite crystals with enhanced crystallinity and reduced defects. Further, we find the different crystallization behaviors probably arise from the inherent structural characteristic of these additives, leading to different interactions in the precursors. This study unveils the effects of amino acids on the liquid–solid crystallization process and helps better understand the role of multifunctional additives beyond their functional groups.

关键词： Perovskite solar cells Multifunctional additives Amino acids Crystallization process

In-situ measurement of mineral phase transition and kinetics in roasting process of Bayan Obo mixed rare earth concentrate by sodium carbonate

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Journal of Rare Earths 2022年第7期40卷 1134-1147页

作者： Peng Zu Jie Li Jingxuan Wu wenhao zhang Jiawei Lin Shiwen Yi Wenrou Su Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resource School of Materials and MetallurgyInner Mongolia University of Science and TechnologyBaotou 014010China Key Laboratory of New Metal Materials of Inner Mongolia Autonomous Region Inner Mongolia University of Science and TechnologyBaotou 014010China

In this study,the Bayan Obo rare earth concentrates mixed with Na_(2)CO_(3)were used for roasting *** phase change process of each firing stage was *** kinetic mechanism model of the continuous heating process was *** study aims to recover valuable elements and optimize the production process to provide a certain theoretical *** X-ray diffraction(XRD),Fourier infrared spectroscopy,scanning electron microscopy with energy dispersive spectrometry,the reaction process and the existence of mineral phases were *** variable temperature XRD and thermogravimetric method were used to calculate the roasting *** phase transition results show that carbonate-like substances first decompose into fine mineral particles,and CaO,MgO,and SiO_(2)react to form silicates,causing ***,REPO_(4)and NaF can directly generate CeF_(3) and CeF_(4)at high temperatures,and a part of CeF_(4)and NaF forms a solid solution substance Na_(3)CeF_(7).Rare earth oxides calcined at a high temperature of 750℃were separated to produce Ce_(0.6)Nd_(0.4)O_(1.8),Ce_(4)O_(7),and LaPrO_(3+x).Then,BaSO_(4),Na_(2)CO_(3),and Fe_(2)O_(3)react to form barium ferrite BaFe_(12)O_(19);the kinetic calculation results show that during the continuous heating process,the apparent activation energy E reaches the minimum in the entire reaction stage in the temperature range of 440-524℃,and the reaction order n reaches the maximum,which indicates that the decomposition product REFO significantly impacts the reaction system and reduces the activation *** mechanism function is F(α)=[-In(1-α)]^(1/3).The reaction order n reaches the minimum in the temperature range of 680-757℃,and the apparent activation energy E is *** difficulty of the reaction increases during the final *** reaction mechanism function is F(α)=[1-(1-α)^(1/3)]^(2).Observing the entire reaction stage,the step of controlling the reaction rate changes from random nucleation to th

关键词： Bayan obo rare earth concentrate Na_(2)CO_(3) Mineral phase Roasting kinetics