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Investigation of Spatial Risk Factors for RVF Disease Occurrence Using Remote Sensing &GIS—A Case Study: Sinnar State, Sudan

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Journal of Geographic Information System 2015年第2期7卷 226-257页

作者： Kowther Mohamed Saeed Ahmed Amna Ahmed Hamid abbas doka Remote Sensing & Geographical Information System Master Program Sudan Academic of Sciences (SAS) Khartoum Sudan Remote Sensing & Geographical Information System Program Remote Sensing Authority-National Center for Research Khartoum Sudan College of Agricultural Studies Sudan University of Science & Technology Khartoum Sudan

Rift Valley Fever (RVF) is an emerging, mosquito-borne disease with serious economical and negative implications on human and animal health. This study was conducted to verify the factors which influenced the spatial pattern of Rift Valley Fever occurrence and identified the high risk areas for the occurrence of the disease at Sinner State, Sudan. The normalized difference vegetation index (NDVI) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite and rainfall data in addition to the point data of RVF clinical cases in humans were used in this study. In order to identify the RVF high risk areas, remote sensing data and rainfall data were integrated in a GIS with other information including, soil type, water body, DEM (Digital Elevation Model), and animal routes and analyzed using Spatial Analysis tools. The information on clinical cases was used for verification. The Normalized Difference Vegetation Index (NDVI) was used to describe vegetation patterns of the study area by calculating the mean NDVI. The results of the study showed that, RVF risk increased with the increase in vegetation cover (high NDVI values), and increase in rainfall, which both provided suitable conditions for disease vectors breeding and a good indicator for RVF epizootics. The study concluded that, identification of high risk area for RVF disease improved the understanding of the spatial distribution of the disease and helped in locating the areas where disease was likely to be endemic and therefore preparedness measures should be taken. The identification represents the first step of prospective predictions of RVF outbreaks and provides a baseline for improved early warning, control, response planning, and mitigation. Further detailed studies are recommended in this domain.

关键词： Rift Valley Fever Vector-Borne Diseases Spatial Risk Factors Normalized Difference Vegetation Index (NDVI)

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Exact solutions of the nonlinear differential-difference equations associated with the nonlinear electrical transmission line through a variable-coefficient discrete(G'/G)-expansion method

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Chinese Physics B 2014年第12期23卷 117-123页

作者： Sadou Abdoulkary Alidou Mohamadou Ousmanou Dafounansou Serge Yamigno doka Département des Sciences Physiques Ecole Normale Supérieure Université de Maroua Nonlinear and Complex Systems Group Faculty of Science University of Douala The Abdus Salam International Center for Theoretical Physics

We investigated exact traveling soliton solutions for the nonlinear electrical transmission line. By applying a concise and straightforward method, the variable-coefficient discrete（G /G）-expansion method, we solve the nonlinear differential–difference equations associated with the network. We obtain some exact traveling wave solutions which include hyperbolic function solution, trigonometric function solution, rational solutions with arbitrary function, bright as well as dark solutions.

关键词： nonlinear transmission line discrete(G /G)-expansion method solitary waves

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Diverse chirped optical solitons and new complex traveling waves in nonlinear optical fibers

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Communications in Theoretical Physics 2020年第6期72卷 106-119页

作者： Savaissou Nestor Souleymanou Abbagari Alphonse Houwe Mustafa Inc Gambo Betchewe Serge Y doka Department of Physics Faculty of Sciencethe University of MarouaP O Box 814MarouaCameroon Department of Basic Science Faculty of Mines and Petroleum IndustriesUniversity of MarouaMarouaCameroon Firat University Science FacultyDepartment of Mathematics23119 ElazigTurkey Department of Medical Research China Medical University HospitalChina Medical UniversityTaichungTaiwanChina Department of Physics Faculty of Sciencethe University of NgaoundereP O Box 454Cameroon

This paper studies chirped optical solitons in nonlinear optical ***,we obtain diverse soliton solutions and new chirped bright and dark solitons,trigonometric function solutions and rational solutions by adopting two formal integration *** obtained results take into account the different conditions set on the parameters of the nonlinear ordinary differential equation of the new extended direct algebraic equation *** results are more general compared to Hadi et al(2018 Optik 172545–53)and Yakada et al(2019 Optik197163108).

关键词： diverse chirped optical solitons nonlinear optical fibers new extended direct algebraic method

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Propagation of Dark Solitary Waves in the Korteveg-Devries-Burgers Equation Describing the Nonlinear RLC Transmission

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Journal of Modern Physics 2014年第6期5卷 394-401页

作者： Serge doka Yamigno Department of Physics Higher Teachers’ Training College University of Maroua Maroua Cameroon

We investigate the propagation of dark solitons in a nonlinear dissipative electrical line. We show that the dynamics of the line is reduced to an expanded Korteweg-de Vries-Burgers (KdVB) equation. By applying the perturbation theory to the KdVB equation, we obtain soliton-like pulse solutions. The numerical simulations of the discrete equation are carried out and show the possibility of the founding solution to spread through the line. The effect of the dissipation through soliton is also shown. A chaotic-like behavior can take place in the system during the propagation of dark solitons through the line.

关键词： Nonlinear Electrical Lines Dark Solitons

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Solitary Waves of 1-Nonlinear Schrodinger Equation in the Composite Right-and Left-Handed Metamaterial

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Journal of Partial Differential Equations 2019年第4期32卷 293-303页

作者： HOUWE A. KLOFAI Yerima JUSTIN Mibaile GAMBO Betchewe doka Serge Y. Department of Marine engineering Limbe Nautical Arts and Fisheries InstituteP.O.Box.485 LimbeCameroon Department of Physics Higher Teachers Training CollegeUniversity of MarouaP.O.Box55MarouaCameroon Department of Physics Faculty of ScienceUniversity of MarouaP.O.Box814MarouaCameroon Department of Physics Faculty of ScienceUniversity of NgaoundereP.O.Box454NgaoundreCameroon

In this article,we analyze solitary waves in nonlinear left-handed transmission line with nonlinear diodes(Schottkys)which is an important issue,especially for soliton *** applying the Kirchhoffs laws and reductive direct method,the voltage in the spectral domain was *** the Taylor series around a certain modulation frequency,we obtained one dimensional Nonlinear Schrodinger Equation(NSE),which support envelops soliton,and bright soliton *** sine-cosine mathematical method,soliton solutions of the standard Nonlinear Schrod--inger equation are *** method used is straightforward and concise and can be applied to solve further of nonlinear PDEs in mathematical physics.

关键词： CRLH transmission line nonlinear Schrodinger equation Sine-Cosine method solitary waves

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超临界环己烷介入的重质油减粘裂化

超临界环己烷介入的重质油减粘裂化

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作者： doka Dari Moumouni 华东理工大学

学位级别：硕士

论文在温度320～400℃,环己烷密度0.20～0.35 g/ml以及环己烷与重油质量比2:1～4:1(wt)的范围内考察了超临界环己烷作为溶剂的重油减粘裂化。研究首先评估了不同超临界环己烷热力学条件下的减粘性能,随后将超临界环己烷中的减粘行为与... 详细信息

论文在温度320～400℃,环己烷密度0.20～0.35 g/ml以及环己烷与重油质量比2:1～4:1(wt)的范围内考察了超临界环己烷作为溶剂的重油减粘裂化。研究首先评估了不同超临界环己烷热力学条件下的减粘性能,随后将超临界环己烷中的减粘行为与超临界水和超临界苯环境中的减粘行为进行比较。超临界流体的引入使得决定减粘效率的脱烷基可通过扩散环境的改善而得到有效地加速。由此获得裂化产品粘度和平均分子量的快速下降以及轻质组分含量的增加。尽管在实验所采用的温度条件下脱烷基和缩合处于有利的串联结构,缩合在减粘裂化中始终发挥重要作用。与被认为是惰性的超临界水和超临界苯有所不同,超临界环己烷可作为氢供体参与减粘裂化。在超临界环己烷中,反应初期的减粘效率有所降低,但是在反应中后期的缩合也得到部分抑制。

关键词：减粘裂化重油超临界环己烷供氢脱烷基

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Modeling the Failure Rate of a Standby Multi-Component System and Improving Reliability

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Modern Mechanical Engineering 2023年第1期13卷 21-33页

作者： Aslain Brisco Ngnassi Djami Wolfgang Nzié Serge doka Yamigno Department of Fundamental Sciences and Techniques of Engineer Chemical Engineering and Mineral Industries School University of Ngaoundere Ngaoundere Cameroon Department of Physics Faculty of Science University of Ngaoundere Ngaoundere Cameroon

Evaluating the reliability of a system requires knowledge of the failure modes to which it is subjected. Complex topology systems generally require a high level of availability, which is a function of the arrangement of elements (components) in the system. To avoid serious failures for such complex systems, recourse can be had to the redundancy techniques available in the literature. These techniques help to improve system reliability, without affecting the reliability of system components. This paper is interested in the proposal of a model for evaluating the failure rate of a standby multi-components system and in improving the reliability of mechanical systems, arranged in a topology (series, parallel, or mixed).

关键词： Reliability Modeling Topology Redundancy Availability Failure Rate

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Disassembly Evaluation in Design of a System Using a Multi-Parameters Index

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Modern Mechanical Engineering 2020年第1期10卷 1-16页

作者： Aslain Brisco Ngnassi Djami Wolfgang Nzié Serge doka Yamigno PhD Candidate National Advanced School of Agro-Industrial Sciences University of Ngaoundere Ngaoundere Cameroon Department of Basic Sciences and Techniques for the Engineer EGCIM University of Ngaoundere Ngaoundere Cameroon Department of Physics Faculty of Science University of Ngaoundere Ngaoundere Cameroon

In order to help designers, consider disassembly in their design activities, a method for evaluation of product disassembly is proposed. Criteria characterizing the disassembility of a product are identified. Each criterion is assigned a coefficient, thus proposing an index of easy fixations (Iff) as a design indicator to evaluate the level of disassembly of a solution generated by the designer. This index is calculated as a weighted average of the indicators for evaluating the disassembility of the product. The proposed method uses information such as the list of subsets or parts, the component tree, the part geometry, the functional links between components and parts, the properties of the components. It has been tested on one product: the soy roaster.

关键词： Design Disassembly Criteria Evaluation Indicators

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High Temperature Effect on Absorption Coefficient of M-MPPs and Sandwich Structures Coupled with MPPs

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Open Journal of Acoustics 2020年第1期10卷 1-18页

作者： Daliwa Joseph Bainamndi Emmanuel Siryabe Serge Yamigno doka Guy Edgar Ntamack Groupe de Mé canique des Mat&#233 riaux et Acoustique (GMMA) Universit&#233 de Ngaoundé ré Ngaound&#233 ré Cameroun Safran Helicopter Engines Groupe Evaluation Non Destructive Bordes France

This paper addresses the effect of high temperature on absorption performance of sandwich material coupled with microperforated panels (MPPs) in multiple configurations using a finite element model (FEM) over a frequency range from 10 to 3000 Hz. The structure is backed with a rigid wall which can either be Aluminium or Al-Alloy used in aeronautic or automobile. The wave propagation in porous media is addressed using Johnson Champoux Allard model (JCA). The FEM model developed using COMSOL Multiphysics software makes it possible to predict the acoustic absorption coefficient in multilayer microperforated panels (M-MPPs) and sandwich structure. It is shown that, when structures made by MPPs or sandwich materials are submitted to high temperature, the absorption performance of the structure is strongly modified in terms of amplitude and width of the bandgap. For application in sever environment (noise reduction in engines aircrafts), Temperature is one of the parameters that will most influence the absorption performance of the structure. However, for application in the temperature domain smaller than 50?C (automotive applications for example), the effect of temperature is not significant on absorption performance of the structure.

关键词： Absorption Coefficient Finite Element Model Microperforated Plates Poroelastic Core Sandwich Structures

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CT-Scan Presentations of Brain Malformations in Children: About Three Cases in Regional Hospital of Ngaoundere-Cameroon

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Open Journal of Radiology 2018年第2期8卷 74-83页

作者： Neossi Guena Mathurin Alapha Florent doka Kamo Héléne Department of Biomedical Sciences Faculty of Science The University of Ngaoundere Ngaoundere Cameroon Medical Imaging Center of Ngaoundere Regional Hospital Ngaoundere Cameroon Peadiatric Department of Ngaoundere Regional Hospital Ngaoundere Cameroon

Brain malformations are rare, difficult to diagnose and have unpredictable evolution. They are the major causes of epilepsy, psychomotor development abnormalities and other neurological disorders. The neuroimaging technique of choice for diagnosis of these malformations is magnetic resonance imaging (MRI), but unfortunately MRI is expensive, and is not available in a poor resource country like Cameroon. CT scan associated to clinical signs can help to suspect or to confirm a malformation. The authors report here three cases of malformations discovered during cranial CT scan at the regional hospital of Ngaoundéré. They are Dandy Walker malformation, Sturge Weber’s disease and hemimegalencephaly. These cases contribute to the knowledge of this rare event, and emphasize the importance of CT scan on their diagnosis in the absence of MRI.

关键词： Brain Malformations Cerebral CT-Scan Dandy Walker Sturge Weber Diseases Hemimegalencephaly Poor Resource Country

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