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Magnetization of Coupled Ultrathin Ferromagnetic Films

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Communications in Theoretical Physics 2002年第7期38卷 107-112页

作者： wang huai-yu ZHOU yun-Song wang Chong-yu Department of Physics Tsinghua University Beijing 100084 China Department of Physics Capital Normal University Beijing 100037 China Department of Physics Tsinghua University Beijing 100084 China

The magnetization of coupled ferromagnetic films is calculated by Green's function method. The coupling can either be ferromagnetic or antiferromagnetic. For the latter case, a concept of pseudo-spin is suggested to make calculation possible. A pseudo-spin is actually an anti-spin with its properties being analogue to other known anti particles such as a hole. The decreasing of Curie point as the coupling strength decays is computed. It is noted that with the same strength, antiferromagnetic coupling has higher Curie point than ferromagnetic coupling.

关键词： magnetization, pseudo-spin, coupled ferromagnetic films

Statistical Average of Spin Operators for Calculation of Three-Component Magnetization （II）： Solution of Equation

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Communications in Theoretical Physics 2006年第1期45卷 175-179页

作者： wang huai-yu LONG Yao CHEN Nan-Xian Department of Physics Tsinghua University Beijing 100084 China

In this paper, the solution of Chebyshev equation with its argument being greater than 1 is obtained. The initial value of the derivative of the solution is the expression of magnetization, which is valid for any spin quantum number S. The Chebyshev equation is transformed from an ordinary differential equation obtained when we dealt with Heisenberg model, in order to calculate all three components of magnetization, by many-body Green＇s function under random phase approximation. The Chebyshev functions with argument being greater than 1 are discussed. This paper shows that the Chebyshev polynomials with their argument being greater than 1 have their physical application.

关键词： three-component magnetization Heisenberg model many-body Green's function method ordinary differential equation Chebyshev functions

Theoretical Investigation of Exchange Bias in Compensated Cases

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Communications in Theoretical Physics 2008年第11期50卷 1241-1244页

作者： XIONG Zhi-Jie wang huai-yu DING Ze-Jun Department of Physics University of Science and Technology of China Hefei 230026 China Department of Physics Tsinghua University Beijing 100084 China

The exchange bias （EB） of the ferromagnetic （FM）/antiferromagnetic （AFM） bilayers in a compensated case is studied by use of the many-body Green＇s function method of quantum statistical theory. The so-called compensated case is that there is no net magnetization on the AFM side of the interface. Our conclusion is that the EB in this case is primarily from the asymmetry of the interracial exchange coupling strengths between the FM and the two sublattices of the AFM. The effects of the layer thickness, temperature and the interracial coupling strength oi2 the exchange bias HE are investigated. The dependence of HE on the FM layer thickness and temperature is qualitatively in agreement with experimental results. HE is nearly inversely proportional to FM thickness. When temperature varies, both HE and He decrease with temperature increasing. The anisotropy of the FM layer only slightly influence He, but does not influence HE.

关键词： exchange bias coercivity compensated case Heisenberg Hamiltonian the many-body Green's function method

Spatial variation of technical efficiency of cereal production in China at the farm level

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Journal of Integrative Agriculture 2021年第2期20卷 470-481页

作者： ZHOU Wen-bin wang huai-yu HU Xi DUAN Feng-ying Institute of Crop Sciences Chinese Academy of Agricultural SciencesBeijing 100081P.R.China School of Management and Economics Beijing Institute of TechnologyBeijing 100081P.R.China Agricultural Genomics Institute at Shenzhen Chinese Academy of Agricultural SciencesShenzhen 518108P.R.China

Rice, wheat and maize are the main staple food crops to ensure the food security in China with diversified climate condition, cropping system and environmental and socio-economic factors across provinces. Spatial variation of technical efficiency in farmers' field is helpful to understand the potential to improve farmers' yield given the inputs level and reduce the yield gap. The study is based on a large-scale farm household survey which covered 1 218 rice farmers, 3 566 wheat farmers and 2 111 maize farmers in the main producing areas. The results indicate that rice farmers are with very high technical efficiency level, nearly 0.9 on average, with little room to improve the efficiency of agricultural inputs. Similar results have been found in wheat and maize farmers' fields, although the technical efficiency levels are lower than that of rice farmers while still at a high level with obvious variation across regions. Farmers with higher yield level also achieve better technical efficiency in most locations. Both local environmental and socio-economic factors significantly affect farmers' technical efficiency. In the context of urbanization and economic development, improved and new agricultural technologies need to be prioritized and facilitated to improve cereal yield at farm level.

关键词： technical efficiency spatial variation rice wheat maize

Two-Dimensional Hydrogen Molecule and Its Ions

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Chinese Physics Letters 1998年第3期15卷 173-174页

作者： wang huai-yu SUN Jin-zuo YANG Fu-min Department of Physics Yantai UniversityYantai 264005

The lowest four states of two-dimensional(2D)hydrogen molecule H_(2) and the lowest two states of its ions H_(2)^(+) and H_(2)^(-) are calculated with an applicable 2D hydrogen anion wave function properly *** results are compared with their three-dimensional *** becomes possible to calculate transitions between states of clusters containing two shallow impurities in semiconductor thin films.

关键词： states lowest properly

Critical Point of Ising Films with Different Growth Directions

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Chinese Physics Letters 2000年第1期17卷 55-57页

作者： wang huai-yu ZHOU yun-song D.L.Lin Department of Physics Yantai UniversityYantai 264005 Department of Physics Capital Normal UniversityBeijing 100037 Department of Physics State University of New York at BuffaloBuffaloNY 14260-1500U.S.A.

The critical temperature Tc of a spin-1/2 Ising film of cubic structures is calculated by the variational cumulant expansion method for three directions of *** results from different growth directions are analysed and compared with each *** the present model,the Tc values depend largely on the number of nearest neighbors in a monolayer for films with the same number of monolayers but grown in different *** sc,bcc and fee structures,the highest Tc is found along the(100),(110),and(111)direction,respectively.

关键词： directions Ising variational

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海森伯铁磁系统的总能量

物理学报 2007年第9期56卷 5466-5470页

作者：王怀玉夏青清华大学物理系北京100084 西安机电信息技术研究所西安710065

对于海森伯铁磁系统,利用多体格林函数方法,在无规相近似下,并且考虑到关联函数〈S+S-〉时,得到对于任意自旋S普遍适用的总能量的表达式.对于三维和二维的情况给出了计算结果.得到的总能量的数值低于没有考虑关联函数时的数值.

关键词：海森伯模型铁磁系统总能量关联函数

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3/2接线方式同期回路改造

电力系统保护与控制 2009年第16期37卷 125-127页

作者：王怀玉陕西天龙输变电建设有限公司佛山分公司广东佛山528000

针对许多3/2接线方式的变电站采用旧的同期装置及同期回路在并网时出现的同期问题,分析了问题的主要原因,并通过简化原同期切换回路中刀闸辅助触点串联回路或串联逻辑,提出了3/2接线方式下新的同期电压切换回路和同期装置改善措施,使得... 详细信息

针对许多3/2接线方式的变电站采用旧的同期装置及同期回路在并网时出现的同期问题,分析了问题的主要原因,并通过简化原同期切换回路中刀闸辅助触点串联回路或串联逻辑,提出了3/2接线方式下新的同期电压切换回路和同期装置改善措施,使得3/2接线方式的变电站同期操作趋于合理、完善、安全。

关键词：电力系统 3/2接线同期回路电压切换

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中华医学杂志(英文版) 2024年第20期137卷 2492-2494页

作者： wang huai-yu Bai Minghua wang Jinwei Li Zhuqing wang Ji wang Qi National Institute of Traditional Chinese Medicine Constitution and Preventive Treatment of Diseases Beijing University of Chinese Medicine Beijing China College of Chinese Medicine Beijing University of Chinese Medicine Beijing China Renal Division Department of Medicine Peking University First Hospital Peking University Institute of Nephrology Beijing China

To the Editor:Swallowing-related cough is a common manifestation of oropharyngeal dysphagia,and confirms the risk of aspiration and ***-related death was the common cause of accidental death in old *** of the difficulty of first aid,80% of choked people died before the emergency team arrived,which stresses the importance of monitor and prevention of swallowing-related ***,swallowing disorder intertwines with various aging-related conditions,such as frailty,sarcopenia,and dementia,and is the crossed manifestation of aging-related health ***,swallowing-related cough was mainly considered as one of the screening criteria of dysphagia and risk indicator of aspiration pneumonia,while the actual screening rates in clinical practice were extremely *** guidelines on aspiration pneumonia and dysphagia,which involve swallowing-related cough,recommend to intensify oral care,test for dysphagia,and initiate swallowing rehabilitation *** these actions highly depend on formal caregivers and *** the circumstances lacking formal caregivers,it would be more pragmatic to find an easy-to-notice risk *** geriatric assessment (CGA) was the consented solution of multidisciplinary healthcare of old ***,the initiation of CGA in the circumstances lacking formal caregiver remains *** the perspective of health monitor,the advantage of swallowing-related cough is *** is valuable to investigate the clinical significance of swallowing-related cough on health decline in old adults and determine whether it is a worth-to-use ***,it is also essential to explore the related factor of swallowing-related cough,which could guide the prevention and management of swallowing-related cough,minimizing the need for intensified care among high-risk ***,the present study investigated the prevalence and related factor of swallowing-related cough,a

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