检索结果-南通市图书馆

Navigation Finsler metrics on a gradient Ricci soliton

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 266-275页

作者： LI Ying MO Xiao-huan WANG Xiao-yang department of applied Mathematics Zhejiang University of TechnologyHangzhou 310023China Key Laboratory of pure and applied Mathematics School of Mathematical SciencesPeking UniversityBeijing 100871China School of Mathematics and Statistics Beijing Institute of TechnologyBeijing 100081China

In this paper,we study a class of Finsler metrics defined by a vector field on a gradient Ricci *** obtain a necessary and sufficient condition for these Finsler metrics on a compact gradient Ricci soliton to be of isotropic S-curvature by establishing a new integral *** we determine the Ricci curvature of navigation Finsler metrics of isotropic S-curvature on a gradient Ricci soliton generalizing result only known in the case when such soliton is of Einstein *** its application,we obtain the Ricci curvature of all navigation Finsler metrics of isotropic S-curvature on Gaussian shrinking soliton.

关键词： gradient Ricci soliton navigation Finsler metric isotropic S-curvature Ricci curvature Gaussian shrinking soliton

A new quantity in Finsler geometry

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2024年第4期67卷 883-890页

作者： Xiaohuan Mo Xiaoyang Wang Key Laboratory of pure and applied Mathematics School of Mathematical SciencesPeking UniversityBeijing 100871China School of Mathematics and Statistics Beijing Institute of TechnologyBeijing 100081China

In this paper,we study a new Finslerian quantity■defined by the T-curvature and the angular metric *** show that the■-curvature not only gives a measure of the failure of a Finsler metric to be of scalar flag curvature but also has a vanishing *** find that the■-curvature is closely related to the Riemann curvature,the Matsumoto torsion and theΘ-*** solve ***’s open problem in terms of the■-***,we give a global rigidity result for Finsler metrics of negative Ricci curvature on a compact manifold via the■-curvature,generalizing a theorem previously only known in the case of negatively curved Finsler metrics of scalar flag curvature.

关键词： Finsler metric Finslerian quantity T-curvature -curvature Randers metric

GGA + U Study of the Optical Properties of α-BeH2

在线全文

学校读者我要写书评

暂无评论

Open Journal of applied Sciences 2024年第6期14卷 1507-1511页

作者： Uko Ofe department of pure and applied Physics Veritas University Abuja Nigeria

The optical properties of α-BeH2 in an Orthorhombic crystal structure with the space group (Ibam) are investigated. We have calculated the optical properties including dielelectric function, refractive index and extinction coefficient, using density functional approach. A theoretical explanation of the relationship between the dielectric function and other optical constants has been provided. Furthermore, the real and imaginary components of the dielectric function have been examined. The effects of the exchange-correlation potentials (GGA and GGA + U) applied on this compound’s absorption peaks and edges have also been investigated. It was found that using the GGA + U approximation caused the conduction band to shift, which in turn caused the initial absorption peak to shift.

关键词： Dielectric Function Optical Properties GGA and GGA + U Approximations

Deep bed filtration model for cake filtration and erosion

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 355-372页

作者： L.I.KUZMINA Y.V.OSIPOV A.R.PESTEREV department of applied Mathematics HSE UniversityMoscow 101000Russia department of Computer Science and applied Mathematics Moscow State University of Civil EngineeringMoscow 129337Russia

Many phenomena in nature and technology are associated with the filtration of suspensions and colloids in porous media. Two main types of particle deposition,namely, cake filtration at the inlet and deep bed filtration throughout the entire porous medium, are studied by different models. A unified approach for the transport and deposition of particles based on the deep bed filtration model is proposed. A variable suspension flow rate, proportional to the number of free pores at the inlet of the porous medium, is considered. To model cake filtration, this flow rate is introduced into the mass balance equation of deep bed filtration. For the cake filtration without deposit erosion,the suspension flow rate decreases to zero, and the suspension does not penetrate deep into the porous medium. In the case of the cake filtration with erosion, the suspension flow rate is nonzero, and the deposit is distributed throughout the entire porous medium. An exact solution is obtained for a constant filtration function. The method of characteristics is used to construct the asymptotics of the concentration front of suspended and retained particles for a filtration function in a general form. Explicit formulae are obtained for a linear filtration function. The properties of these solutions are studied in detail.

关键词： deep bed filtration cake filtration porous medium particle deposition and erosion analytical solution concentration front

Tuning the optoelectronic properties for small organic compounds as organic solar cell applications

在线全文

学校读者我要写书评

暂无评论

Optoelectronics Letters 2024年第7期20卷 412-417页

作者： Hussein K.Mejbel Lafy F.Al-Badry department of Physics College of Education for Pure Science University of Thi-Qar department of Physics College of Science University of Thi-Qar

Recently, organic solar cells have attracted the attention of many researchers owing to flexibility, low cost, light weight and large-area applications, and significant improvement in the power conversion efficiency（PCE）. In this work, we designed chains from organic compounds as donors and replaced the core unit in each series with a variety of acceptors in order to enhance their optical and electronic characterization and performance for power conversion efficiencies in organic solar cells. We utilized density functional theory（DFT） and time-dependent density functional theory（TD-DFT） to investigate the geometry optimization by using the Gaussian 09 program. Both electronic and optical properties were determined, which involve the lowest unoccupied molecular orbital（LUMO） and the highest occupied molecular orbital（HOMO） levels, the band gap energy, maximum absorption wavelength(λ;max;), open circuit voltage(V;oc;), and light harvesting efficiency（LHE）. Our evaluation denotes that the small compounds suggested are predicted to exhibit the best performance compared to the first series（SC1）, like a lower band gap energy, a lower HOMO energy level, a greater absorption range, and a larger PCE.

关键词： A

Nonlinear interaction of head-on solitary waves in integrable and nonintegrable systems

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第5期33卷 480-487页

作者：张树甜刘世鲲矫滕菲孙敏胡凤兰黄德财 department of applied Physics Nanjing University of Science and TechnologyNanjing 210094China

This study numerically investigates the nonlinear interaction of head-on solitary waves in a granular chain(a nonintegrable system)and compares the simulation results with the theoretical results in fluid(an integrable system).Three stages(the pre-in-phase traveling stage,the central-collision stage,and the post-in-phase traveling stage)are identified to describe the nonlinear interaction processes in the granular *** nonlinear scattering effect occurs in the central-collision stage,which decreases the amplitude of the incident solitary *** with the leading-time phase in the incident and separation collision processes,the lagging-time phase in the separation collision process is *** asymmetrical nonlinear collision results in an occurrence of leading phase shifts of time and space in the post-in-phase traveling *** next find that the solitary wave amplitude does not influence the immediate space-phase shift in the granular *** space-phase shift of the post-in-phase traveling stage is only determined by the measurement position rather than the wave *** results are reversed in the *** increase in solitary wave amplitude leads to decreased attachment,detachment,and residence times for granular chains and *** the immediate time-phase shift,leading and lagging phenomena appear in the granular chain and the fluid,*** results offer new knowledge for designing mechanical metamaterials and energy-mitigating systems.

关键词： integrable system nonintegrable system granular chain solitary wave

Enhancing Patients Outcomes and Infection Control through Smart Indoor Air Quality Monitoring Systems

在线全文

学校读者我要写书评

暂无评论

Journal of Computer and Communications 2024年第6期12卷 25-37页

作者： Othniel Ojochonu Abalaka Joe Essien Calistus Chimezie Martin Ogharandukun department of Computer Science Veritas University Abuja Nigeria department of pure and applied Physics Veritas University Abuja Nigeria

Air pollution poses a critical threat to public health and environmental sustainability globally, and Nigeria is no exception. Despite significant economic growth and urban development, Nigeria faces substantial air quality challenges, particularly in urban centers. While outdoor air pollution has received considerable attention, the issue of indoor air quality remains underexplored yet equally critical. This study aims to develop a reliable, cost-effective, and user-friendly solution for continuous monitoring and reporting of indoor air quality, accessible from anywhere via a web interface. Addressing the urgent need for effective indoor air quality monitoring in urban hospitals, the research focuses on designing and implementing a smart indoor air quality monitoring system using Arduino technology. Employing an Arduino Uno, ESP8266 Wi-Fi module, and MQ135 gas sensor, the system collects real-time air quality data, transmits it to the ThingSpeak cloud platform, and visualizes it through a user-friendly web interface. This project offers a cost-effective, portable, and reliable solution for monitoring indoor air quality, aiming to mitigate health risks and promote a healthier living environment.

关键词： Artificial Intelligence Air Pollution Infection Control Data Transmission Data Acquisition Sensors

Emerging perovskite materials for supercapacitors:Structure,synthesis,modification,advanced characterization,theoretical calculation and electrochemical performance

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第2期89卷 41-70,I0003页

作者： Yuehua Qian Qingqing Ruan Mengda Xue Lingyun Chen department of applied Chemistry School of Chemistry and Chemical EngineeringChongqing UniversityChongqing 401331China

As a new generation electrode materials for energy storage,perovskites have attracted wide attention because of their unique crystal structure,reversible active sites,rich oxygen vacancies,and good *** this review,the design and engineering progress of perovskite materials for supercapacitors(SCs)in recent years is ***,the review will focus on four types of perovskites,perovskite oxides,halide perovskites,fluoride perovskites,and multi-perovskites,within the context of their intrinsic structure and corresponding electrochemical performance.A series of experimental variables,such as synthesis,crystal structure,and electrochemical reaction mechanism,will be carefully analyzed by combining various advanced characterization techniques and theoretical *** applications of these materials as electrodes are then featured for various ***,we look forward to the prospects and challenges of perovskite-type SCs electrodes,as well as the future research direction.

关键词： Perovskite Modification engineering Oxygen vacancy Theoretical calculation methodology Supercapacitor

Bald Eagle Search Optimization Algorithm Combined with Spherical Random Shrinkage Mechanism and Its Application

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2024年第1期21卷 572-605页

作者： Wenyan Guo Zhuolin Hou Fang Dai Xiaoxia Wang Yufan Qiang department of applied Mathematics School of ScienceXi'an University of TechnologyXian 710054ShaanxiChina

Over the last two decades,stochastic optimization algorithms have proved to be a very promising approach to solving a variety of complex optimization *** eagle search optimization(BES)as a new stochastic optimization algorithm with fast convergence speed has the ability of prominent optimization and the defect of collapsing in the local *** avoid BES collapse at local optima,inspired by the fact that the volume of the sphere is the largest when the surface area is certain,an improved bald eagle search optimization algorithm(INMBES)integrating the random shrinkage mechanism of the sphere is ***,the INMBES embeds spherical coordinates to design a more accurate parameter update method to modify the coverage and dispersion of the ***,the population splits into elite and non-elite groups and the Bernoulli chaos is applied to elite group to tap around potential solutions of the *** non-elite group is redistributed again and the Nelder-Mead simplex strategy is applied to each group to accelerate the evolution of the worst individual and the convergence process of the *** results of Friedman and Wilcoxon rank sum tests of CEC2017 in 10,30,50,and 100 dimensions numerical optimization confirm that the INMBES has superior performance in convergence accuracy and avoiding falling into local optimization compared with other potential improved algorithms but inferior to the champion algorithm and ranking *** three engineering constraint optimization problems and 26 real world problems and the problem of extracting the best feature subset by encapsulated feature selection method verify that the INMBES’s performance ranks first and has achieved satisfactory accuracy in solving practical problems.

关键词： Bald eagle search optimization algorithm Spherical coordinates Chaotic variation Simplex method Encapsulated feature selection