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searching For(2+1)-dimensional nonlinear Boussinesq equation from(1+1)-dimensional nonlinear Boussinesq equation

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Communications in Theoretical Physics 2023年第7期75卷 58-61页

作者： Man Jia s y Lou school of Physical science and Technology Ningbo UniversityNingbo315211China

A novel(2+1)-dimensional nonlinear Boussinesq equation is derived from a(1+1)-dimensional Boussinesq equation in nonlinear schr?dinger type based on a deformation *** integrability of the obtained(2+1)-dimensional Boussinesq equation is guaranteed by its Lax pair obtained directly from the Lax pair of the(1+1)-dimensional Boussinesq *** of the effects of the deformation,the(2+1)-dimensional Boussinesq equation admits a special travelling wave solution with a shape that can be deformed to be asymmetric and/or multivalued.

关键词： (2+1)-dimensional Boussinesq equation deformation algorithm lax integrable an implicit travelling wave solution

Aqueous electrocatalytic N2 reduction under ambient conditions

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nano Research 2018年第6期11卷 2992-3008页

作者： na Cao Gengfeng Zheng Laboratory of Advanced Materials Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Collaborative Innovation Center of Chemistry for Energy Materials Fudan University Shanghai200438 China

Recently, the electrochemical N2 reduction reaction （NRR） in aqueous electrolytes at ambient temperature and pressure has demonstrated its unique advantages and potentials. The reactants are directly derived from gaseous N2 and water, which are naturally abundant, and NH3 production is important for fertilizers and other industrial applications. To improve the conversion yield and selectivity （mainly competing with water reduction）, electrocatalysts must be rationally designed to optimize the mass transport, chemisorption, and transduction pathways of protons and electrons. In this review, we summarize recent progress in the electrochemical NRR. studies of electrocatalyst designs are summarized for different categories, including metal-based catalysts, metal oxide-derived catalysts, and hybrid catalysts. strategies for enhancing the NRR performance based on the facet orientation, metal oxide interface, crystallinity, and nitrogen vacancies are presented. Additional system designs, such as lithium-nitrogen batteries, and the solvent effect are introduced. Finally, existing challenges and prospects are discussed.

关键词： N2 reduction electrocatalyst aqueous electrolyte faradaic efficiency

One step Positive Approach for sheet Metal Forming simulation Based on Quasi-conjugate-gradient Method

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Chinese Journal of Mechanical Engineering 2013年第4期26卷 730-736页

作者： na Jingxin CHEN Wei state Key Laboratory of Automotive simulation and Control Jilin University

In one step inverse finite element approach, an initial blank shape is normally predicted from the final deformed shape. The final deformed shape needs to be trimmed into a final part after stamping, the trimmed area, therefore, needs to be compensated manually before using one step inverse approach, which causes low efficiency and in consistency with the real situation. To solve this problem, one step positive approach is proposed to simulate the sheet metal stamping process. Firstly the spatial initial solution of one step positive method is preliminarily obtained by using the mapping relationship and area coordinates, then based on the deformation theory the iterative solving is carried out in three-dimensional coordinate system by using quasi-conjugate-gradient method. During iterative process the contact judgment method is introduced to ensure that the nodes on the spatial initial solution are not separated from die surface. The predicted results of sheet metal forming process that include the shape and thickness of the stamped part can be obtained after the iterative solving process. The validity of the proposed approach is verified by comparing the predicted results obtained through the proposed approach with those obtained through the module of one step inverse approach in Autoform and the real stamped part. In one step positive method, the stamped shape of regular sheet can be calculated fast and effectively. During the iterative solution, the quasi-conjugate-gradient method is proposed to take the place of solving system of equations, and it can improve the stability and precision of the algorithm.

关键词： positive approach deformation theory quasi-conjugate-gradient method

Improved scheme with cooperative diversity based on distributed space-time block coding

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Journal of systems Engineering and Electronics 2009年第3期20卷 463-469页

作者： Du na Xu Dazhuan Coll. of Information science & Technology Nanjing Univ. of Aeronautics and Astronautics Nanjing 210016 P. R. China

An improved scheme with cooperative diversity based on distributed space-time block coding （WCD- DsTBC） is proposed, which effectively achieves diversity gains and improves the performance of the system by sharing some single-antenna users＇ antennas to form a virtual antenna array and combining with distributed spacetime block coding （DsTBC） mode. Then the relation between the system BER and the interuser BER for WCDDsTBC scheme is theoretically derived and the closed-form expression of BER for WCD-DsTBC system is obtained. The simulation results show that the proposed WCD-DsTBC scheme achieves distinct gains over the non-cooperative multi-carrier CDMA （MC-CDMA） system. When system BER is le-3 and interuser BER is le-3, about 2.5 dB gain can be gotten. When interuser channel state information （CsI） outgoes the users＇ individual CsI, about 3 dB gain is also achieved.

关键词： multiple input multiple output cooperative diversity distributed space-time block coding multicarrier CDMA.

Automatic image enhancement by learning adaptive patch selection

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Frontiers of Information Technology & Electronic Engineering 2019年第2期20卷 206-221页

作者： na LI Jian ZHANG school of science and Technology Zhejiang International Studies University

Today, digital cameras are widely used in taking photos. However, some photos lack detail and need enhancement. Many existing image enhancement algorithms are patch based and the patch size is always fixed throughout the image. Users must tune the patch size to obtain the appropriate enhancement. In this study,we propose an automatic image enhancement method based on adaptive patch selection using both dark and bright channels. The double channels enhance images with various exposure problems. The patch size used for channel extraction is selected automatically by thresholding a contrast feature, which is learned systematically from a set of natural images crawled from the web. Our proposed method can automatically enhance foggy or under-exposed/backlit images without any user interaction. Experimental results demonstrate that our method can provide a significant improvement in existing patch-based image enhancement algorithms.

关键词： Image enhancement Contrast enhancement Dark channel Bright channel Adaptive patch based processing

Analytical Criteria for Local Activity of CNN with Two-port and Application to Biochemical Model

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International Journal of Minerals,Metallurgy and Materials 2000年第4期14卷 305-314页

作者： Lequan Min na yu Applied science school University of Science and Technology BeijingBeijing 100083China

The analytic criteria are presented for the local activity theory in two-port Cellular Neural Network (CNN) cells with three local state variables, and the application to a Biochemical Model CNN (BMCNN) is given for coupling in series of two enzymes whose prototype was studied by Decroly and Goldbeter. The bifurcation diagrams of the BMCNN's show that there does not exist a locally passive domain, and the computer simulation exhibited that convergent patterns, oscillatory patterns or chaotic patterns may emerge if the selected cell parameters are located in locally active unstable domains but nearby the edge of chaos domain. In particular, the coexistence of multiple oscillations was observed in the corresponding triple cell couples of the BMCNN's with the same initial conditions.

关键词： Cellular neural networks

Lateral Flight stability of Two Hovering Model Insects

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Journal of Bionic Engineering 2014年第3期11卷 439-448页

作者： na Xu Mao sun Ministry-of-Education Key Laboratory of Fluid Mechanics Beihang University Beijing 100191 P. R. China

The longitudinal disturbance motion of different insects at hovering flight has the same modal structure. Here, we consider the case of lateral motion. The lateral dynamic flight stability of two model insects, hoverfly and honeybee, at hovering flight is studied. The method of computational fluid dynamics is applied to compute the stability derivatives. The techniques of eigenvalue and eigenvector analysis are used to solve the equations of motion. Results show that the lateral disturbance motion of the hoverfly has three natural modes of motion： an unstable divergence mode, a stable oscillatory mode and a stable subsidence mode, and the flight is unstable; while the honeybee has a different modal structure （a stable slow subsidence mode, a stable fast subsidence mode, and a nearly neutrally stable oscillatory mode） and the flight is nearly neutrally stable. The change in modal structure between the two insects is due to their roll-moment/side-velocity derivative having different sign, and the sign difference is because that the hoverfly has a relatively small, but the honeybee has a relatively large, distance between the wing roots and the center of mass. Thus, unlike the case of longitudinal motion, for lateral motion, some insects have different modal structures and stability properties from others.

关键词： insect hovering flight dynamic flight stability modal structure

Improving maintenance efficiency and safety through a human-centric approach

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Advances in Manufacturing 2021年第1期9卷 104-114页

作者： C.y.siew s.K.Ong A.y.C.Nee Graduate school for Integrative sciences and Engineering National University of Singapore28 Medical DriveSingapore 117456Singapore Department of Mechanical Engineering National University of Singapore9 Engineering Drive 1Singapore 117576Singapore

This paper presents an adaptive human-machine interface(HMI)that can provide appropriate sets of digital maintenanceinformation and guidance to an operator during *** takes into consideration the expertise level of the operator and the maintenance context and *** proposed human-centric methodology considers the heart rate,intention,and expertise level of the operator,which can be captured using sensors during maintenance.A set of rules is formulated based on the sensor data to infer the state of the operator during a maintenance *** on the operator state,the adaptive HMI can augment the operator's senses using a scheme that combines visual,audio,and haptic guidance cues during maintenance to enhance the operator's ability to perceive information and perform maintenance *** schemes of visual,audio,and haptic cues are developed based on a comparison of the best practices obtained from experienced operators.

关键词： Augmented reality(AR) Ergonomics Product development Maintenance

BOUNDs ON AVERAGE CONTROLLED DIRECT EFFECTs WITH AN UNOBsERVED REsPONsE VARIABLE

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Journal of systems science & Complexity 2011年第6期24卷 1154-1164页

作者： na sHAN Jianhua GUO Key Laboratory for Applied statistics of Ministry of Education School of Mathematics and Statistics Northeast Normal University Changchun 130024 China school of Basic science Changchun University of Technology Changchun 130012 China

This paper considers the problem of estimating the bounds on the average controlled direct effects （ACDEs） of a treatment variable on an unobserved response variable in the presence of unobserved confounders between an intermediate variable and the response variable. When the response variable is observed, Cai, et al.（2008） derived the formulas for the sharp bounds on the ACDEs. When the response variable is unobserved, the authors propose a graphical criterion for selecting variables affected by the response variable to derive the formulas for the bounds on the ACDEs, which is an extension of the result of Kuroki（2005） to ACDEs. The results enable us not only to judge from the graph structure whether the bounds on the ACDEs can be expressed through observed variables when the response variable is unobserved, but also to provide their formulas when the answer is affirmative.

关键词： Average controlled direct effect causal network d-separation