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Communications in Theoretical Physics 2023年第6期75卷 39-50页

作者： H I Abdel-Gawad Mathematics Department Faculty of Science Cairo University GizaEgypt

The wave-operator nonlinear Schrödinger equation was introduced in the ***,nonlocal space-time reverse complex field equations were also recently *** in this area were focused on employing the inverse scattering method and Darboux ***,we present an approach to find the solutions of the wave-operator nonlinear Schrödinger equation with space and time reverse(W-O-NLSE-STR).It is based on implementing the unified method together with introducing a conventional formulation of the ***,a field and a reverse field may be ***,for deriving the solutions of W-O-NLSE-STR,it is evident to distinguish two cases(when the field and its reverse are interactive or not-interactive).In the non-interactive and interactive cases,exact and approximate solutions are *** both cases,the solutions are evaluated numerically and they are displayed *** is observed that the field exhibits solitons propagating essentially(or mainly)on the negative space variable,while those of the reverse field propagate on the other side(or vice versa).These results are completely novel,and we think that it is an essential behavior that characterizes a complex field system with *** the other hand,they may exhibit right and left cable patterns(or vice versa).It is found that the solutions of the field and its reverse exhibit self-phase modulation by solitary *** the interactive case,the pulses of the field and its reverse propagate in the whole *** analysis of modulation stability shows that,when the field is stable,its reverse is unstable or both are *** holds whenever the polarization of the medium is selfdefocusing.

关键词： wave-operator nonlinear Schrödinger equation space-time reverse unified method

A Formulation of the Porous Medium Equation with Time-Dependent Porosity: A Priori Estimates and Regularity Results

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Applied Mathematics 2024年第10期15卷 745-763页

作者： koffi B. Fadimba Department of Computer Science Engineering and Mathematics University of South Carolina Aiken Aiken USA

We consider a generalized form of the porous medium equation where the porosity ϕis a function of time t: ϕ=ϕ(x,t): ∂(ϕS)∂t−∇⋅(k(S)∇S)=Q(S).In many works, the porosity ϕis either assumed to be independent of (or to depend very little of) the time variable t. In this work, we want to study the case where it does depend on t(and xas well). For this purpose, we make a change of unknown function V=ϕSin order to obtain a saturation-like (advection-diffusion) equation. A priori estimates and regularity results are established for the new equation based in part on what is known from the saturation equation, when ϕis independent of the time t. These results are then extended to the full saturation equation with time-dependent porosity ϕ=ϕ(x,t). In this analysis, we make explicitly the dependence of the various constants in the estimates on the porosity ϕby the introduced transport vector w, through the change of unknown function. Also we do not assume zero-flux boundary, but we carry the analysis for the case Q≡0.

关键词： Porous Medium Equation Porosity Saturation Equation A Priori Estimates Regularity Results

Energy Dissipation and Transport in Nanoscale Devices

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Nano Research 2010年第3期3卷 147-169页

作者： eric Pop Department of Electrical and Computer Engineering Micro and Nanotechnology Lab and Beckman InstituteUniversity of Illinois Urbana ChampaignUrbana IL 61801USA

Understanding energy dissipation and transport in nanoscale structures is of great importance for the design of energy-efficient circuits and energy-conversion *** is also a rich domain for fundamental discoveries at the intersection of electron,lattice(phonon),and optical(photon)*** review presents recent progress in understanding and manipulation of energy dissipation and transport in nanoscale solid-state ***,the landscape of power usage from nanoscale transistors(~10^(-8) W)to massive data centers(~10^(-9) W)is ***,focus is given to energy dissipation in nanoscale circuits,silicon transistors,carbon nanostructures,and semiconductor *** of steady-state and transient thermal transport are also reviewed in the context of nanoscale devices with sub-nanosecond switching ***,recent directions regarding energy transport are reviewed,including electrical and thermal conductivity of nanostructures,thermal rectification,and the role of ubiquitous material interfaces.

关键词： Nanowire nanotube interface thermal transport rectification thermoelectric power dissipation

Ipsilateral hemifacial microsomia with dextrocardia and pulmonary hypoplasia:A case report

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World Journal of Clinical Cases 2022年第9期10卷 2948-2953页

作者： Rui Guo Shi-hi Chang Bing-Qing Wang Qing-Guo Zhang Department of Ear Reconstruction Plastic Surgery HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100000China

BACKGROUND Hemifacial microsomia(HFM)is a rare congenital malformation characterized by a combination of various anomalies,including the face,ears,eyes,and *** diagnosis for HFM is possible,and quite accurate ultrasound can detect obvious *** etiology is still unknown,although some hypotheses have been proposed,including gene mutation,chromosome anomaly,and environmental risk ***,there are few reports of pulmonary hypoplasia and dextrocardia in *** SUMMARY A 2-year-old boy presented to the ear reconstruction department of our hospital complaining of deviation of the face to the right side and auricular *** examination revealed facial asymmetry,preauricular skin tags,and concha-type microtia with stricture of the external auditory canal on the right *** magnetic resonance imaging showed bilateral semicircular canal dysplasia and bilateral internal auditory canals *** examination showed bilateral severe sensorineural hearing *** radiography and computed tomography showed dextrocardia and right pulmonary *** This case presented a rare finding and an unusual association of 3 malformations,ipsilateral HFM,pulmonary agenesis,and dextrocardia.

关键词： Hemifacial microsomia Oculoauriculovertebral spectrum Dextrocardia Pulmonary hypoplasia Congenital anomaly Case report

A New Unified Stabilized Mixed Finite Element Method of the Stokes-Darcy Coupled Problem: Isotropic Discretization

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Journal of Applied Mathematics and Physics 2021年第7期9卷 1673-1706页

作者： Houédanou koffi Wilfrid Département de Mathématiques Université d’Abomey-Calavi (UAC) Abomey-Calavi Benin

In this paper, we develop an a-priori error analysis of a new unified mixed finite element method for the coupling of fluid flow with porous media flow in RN, N ∈ {2,3}, on isotropic meshes. Flows are governed by the Stokes and Darcy equations, respectively, and the corresponding transmission conditions are given by mass conservation, balance of normal forces, and the Beavers-Joseph-Saffman law. The approach utilizes a modification of the Darcy problem which allows us to apply a variant nonconforming Crouzeix-Raviart finite element to the whole coupled Stokes-Darcy problem. The well-posedness of the finite element scheme and its convergence analysis are derived. Finally, the numerical experiments are presented, which confirm the excellent stability and accuracy of our method.

关键词： Coupled Stokes and Darcy Flows Nonconforming Finite Element Method Crouzeix-Raviart Element

The Impact of Chinese Trade and Investment on West African Economic Growth: A Spatial Econometrics Approach

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Open Journal of Applied Sciences 2020年第4期10卷 142-153页

作者： Hua Wilfried Serge koffi School of Economics Shanghai University Shanghai China

This paper has studied the West African region or Economic Community of West African States (ECOWAS) which includes fifteen countries and its relationship with China. Three countries (Cote d’Ivoire, Ghana, and Nigeria) of the fifteen countries which are economically representative in the west African region to represent the overall-region were studied. Therefore, the objective of this study is to investigate the spatial effect of Chinese trade and investment on the economic growth of West Africa. The study focuses on the period from 1960-2014 using the dynamic panel data approach and spatial autoregressive approach for the econometric analysis of this topic. Empirically, the results show that trade openness with China has a positive impact on the neighboring countries of the region, especially for those who share the same border. Chinese investment is vital to the region’s economic growth as the results show that one dollar investment increase from China to the host country increases the economic growth in the neighboring countries by 0.328%.

关键词： China Trade Investment West Africa Economic Community of West African States (ECOWAS) Economic Growth

Satellite monitoring of land-use and land-cover changes in northern Togo protected areas

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Journal of Forestry Research 2014年第2期25卷 385-392页

作者： Fousseni Folega Chun-yu Zhang Xiu-hai Zhao Kperkouma Wala Komlan Batawila Hua-guo Huang Marra Dourma koffi Akpagana The Key Laboratory for Silviculture and Conservation of Ministry of Education Beijing Forestry University Université de Lomé Laboratoire de botanique et écologie végétaleFaculté des sciences

Remote-sensing data for protected areas in northern Togo, obtained in three different years （2007, 2000, and 1987）, were used to assess and map changes in land cover and land use for this drought prone zone. The normalized difference vegetation index （NDVI） was applied to the images to map changes in vegetation. An unsupervised classification, followed by classes recoding, filtering, identifications, area computing and post-classification process were applied to the composite of the three years of NDVI images. Maximum likelihood classification was applied to the 2007 image （ETM＋2007） using a supervised classification process. Seven vegetation classes were defined from training data sets. The seven classes included the following biomes： riparian forest, dry forest, flooded vegetation, wooded savanna, fallows, parkland, and water. For these classes, the overall accuracy and the overall kappa statistic for the classi- fied map were 72.5% and 0.67, respectively. Data analyses indicated a great change in land resources; especially between 1987 and 2000 proba- bly due to the impact of democratization process social, economic, and political disorder from 1990. Wide-scale loss of vegetation occurred during this period. However, areas of vegetation clearing and regrowth were more visible between 2000 and 2007. The main source of confusion in the contingency matrix was due to heterogeneity within certain classes. It could also be due to spectral homogeneity among the classes. This research provides a baseline for future ecological landscape research and for the next management program in the area.

关键词： land change NDVI land cover protected areas Northern Togo

Assessing Levels and Health Risks of Fluoride and Heavy Metal Contamination in Drinking Water

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Journal of Geoscience and Environment Protection 2022年第11期10卷 15-34页

作者： Ali Sanou Namory Méité Amadou Kouyaté Elisephane Irankunda Alfred Niamien Kouamé Aka eric koffi koffi Jean-Paul Bohoussou Lébé Prisca M.-S. Kouakou Institut National Polytechnique Félix Houphouë t-Boigny (INP-HB) Laboratoire des Procédés Industriels de Synthèses de l’Environnement et des Energies Nouvelles (LAPISEN) Yamoussoukro C&#244 te d’Ivoire Institut National Polytechnique Félix Houphouë t-Boigny (INP-HB) Laboratoire de Thermodynamique Traitement et Sciences des Surfaces et Interfaces Ingénierie et Physicochimie des Procédés et de Mécanique des Matériaux (L2-TSIPM) Yamoussoukro C&#244 te d’Ivoire Ecole Normale Supérieure (ENS) Laboratoire des Sciences Physiques Fondamentales et Appliquées (LSPFA) Abidjan C&#244 te d’Ivoire Université Félix Houphouë t-Boigny (UFHB) UFR SSMT Laboratoire de Constitution et Réaction de la Matière (LCRM) Abidjan C&#244 te d’Ivoire Université Félix Houphouë t-Boigny (UFHB) UFR SSMT Laboratoire de Constitution et Réaction de la Matière (LCRM) Abidjan C&#244te d’Ivoire Laboratoire des Sciences et Technologies de l’Environnement UFR Environnement Université Jean Lorougnon Guédé Daloa C&#244 te d’Ivoire School of Computer Science and Information Technology The East African University Kajiado Kenya

A systematic study was carried out to assess the level of contamination with fluorides and heavy metals in the drinking water of the city of Daloa as well as the risks to the health of consumers. The waters of 11.11% of the sites sampled exceeded the fluoride limit for drinking water with a contamination index (CI) greater than 0. All the waters recorded concentrations of cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn) and lead (Pb) above the recommended values with CI > 0. However, 22.22% of the sites recorded concentrations below the standard for zinc (Zn) with IC hildren except for Zn where the CDI > 1 for children in 22.22% of drinking water studied. HQs have an average of less than 1 for fluorine and greater than 1 for all metals. Moreover, the danger indices have values greater than 1. The incremental lifetime cancer risk (ILCR) and the total ILCR are above the recommended values. These results showed that the drinking water sampled is of poor quality due to higher levels of heavy metals, which can constitute a danger to human health. Long-term use of one of these poor quality waters can lead to cancer in consumers. It is therefore necessary to treat this water in order to eliminate the metals before using it for drinking. This study can help decision-makers and competent authorities in charge of water management.

关键词： Physico-Chemical Parameters Fluoride Heavy Metals Drinking Water Sanitary Risks

Statistics of oxidation resistance of Ni-(0-15)Co-(8-15)Cr-(0-5)Mo-(0-10)W-(3-8)Al-(0-5)Ti-(0-10)Ta-0.1C-0.01B superalloys at 1000℃ by compositional variations

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Rare Metals 2020年第8期39卷 918-927页

作者： Si-Jun Park Kyu-Hyuk Lee Seong-Moon Seo hi-Won Jeong Young-Soo Yoo HeeJin Jang Multi-Material Research Center Gwangju-Jeonnam DivisionKorea Automotive Technology InstituteGwangju 62207Republic of Korea Department of Advanced Materials Engineering Chosun UniversityGwangju 61452Republic of Korea high Temperature Materials Group Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Engineering Chosun UniversityGwangju 61452Republic of Korea

The effects of alloying elements(Co,Cr,Mo,W,Al,Ti,and Ta)on the oxidation resistance of Ni-(0-15)Co-(8-15)Cr-(0-5)Mo-(0-10)W-(3-8)Al-(0-5)Ti-(0-10)Ta-0.1 C-0.01 B alloys were *** sample compositions were designed by the Box-Behnken method of design of experiments(DOE).The alloying elements show complicated effects on the mass gain due to oxidation,depending on the alloy *** reduces the mass gain *** other elements except Al do not appear to exert a strong effect on the oxidation rate on average,but their influences are shown clearly in the alloys with a low Al ***,W,and Ta reduce the oxidation rate,while Cr,Mo,and Ti promote *** is the most effective element in reducing the oxidation rate of the alloy with a low Al *** is confirmed that a continuous Al2O3 layer is essentially required for high oxidation *** oxide scale of easily oxidized alloys has various oxides such as NiCr2O4,NiAl2O4,NiO,Cr2O3,CrTaO4,and TiO2.

关键词： high temperature oxidation Alloy composition Ni-based superalloy Oxidation resistance Design of experiments

Pressure/Saturation System for Immiscible Two-Phase Flow: Uniqueness Revisited

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Applied Mathematics 2011年第5期2卷 541-550页

作者： koffi B. Fadimba 不详

We give a sufficient condition for uniqueness for the pressure/saturation system. We establish this condition through analytic arguments, and then construct 'mobilities' (or mobility-like functions) that satisfy the new condition (when the parameter is 2). For the constructed 'mobilities', we do graphical experiments that show, empirically, that this condition could be satisfied for other values of . These empirical experiments indicate that the usual smoothness condition on the fractional flow function (and on the total mobility), for uniqueness and convergence, might not be necessary. This condition is also sufficient for the convergence of a family of perturbed problems to the original pressure/saturation problem.

关键词： Porous Medium Uniqueness of a Solution Degenerate Equation Immiscible Two-Phase Flow Regularization Phase Mobility.