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Journal of Magnesium and Alloys 2024年第3期12卷 954-965页

作者： Yimeng Chen Manuel Legrée jean-louis Bobet Alexander Kvit CAMECA Instruments Inc MadisonWI 53711USA ICMCB Universitéde BordeauxPessacCEDEX 33608France NIAC&Materials Science Department University of WisconsinMadisonWI 53706USA

The long-period-stacking-ordered(LPSO)structure affects the mechanical,corrosion and hydrolysis properties of Mg *** current work employs high angle annular dark field-scanning transmission electron microscopy(HAADF-STEM)and atom probe tomography(APT)to investigate the structural and local chemical information of LPSO phases formed in Mg-Ni-Y/Sm ternary alloys after extended isothermal *** on the alloying elements and their concentrations,Mg-Ni-Y/Sm develops a two-phase LPSO+α-Mg structure in which the LPSO phase contains defects,hybrid LPSO structure,and Mg ***-STEM and APT indicate non-stoichiometric LPSO with incomplete Ni_(6)(Y/Sm)_(8) *** addition,the APT quantitatively determines the local composition of LPSO and confirms the presence of Ni within the Mg bonding *** results provide insight into a better understanding of the structure and hydrolysis properties of LPSO-Mg alloys.

关键词： Magnesium alloys Long-range ordering Atom probe tomography(APT) STEM HAADF Hydrolysis properties.

Joint Management of Shared Resources, Issues and Conflicts of the Nso and Oku Tribes in the Ngongbaa Montane Forest Area, NWR of Cameroon

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Natural Resources 2024年第6期15卷 149-172页

作者： jean-louis Tatah Elvis Kah Department of Geography Faculty of Arts Letters and Social Sciences University of Yaounde I Yaounde Cameroon School of Geology and Mining Engineering University of Ngaoundere Ngaoundere Cameroon

Wherever people live together in or near homelands that harbour joint natural resources such as forest, water, minerals, oil etc., they must collaborate, co-exist and share these resources irrespective of their genetic, social, cultural, and political peculiarities. This is not always the case when self-interest, ethnic divisions, elitist politics, economic interest and power tussle set in. The Nso and Oku people who reside in the Ngongbaa Forest area constitute an example of joint management of resources where at one period, their relationship over the management of the Oku Mountain Forest was cordial and at another, the relationship became conflictive. This study was designed to study the influence of the KIFP forest management policies on the Nso indigenous forest Management system in Ngongbaa Forest, and its implications. The data collected for the study was secured through the administration of a questionnaire to residents of 10 villages adjacent to the Ngongbaa Forest, and forest users who carried out livelihood activities there between 1963 and 2015. These forest user groups include beekeepers, rat trappers, grazers, mushroom gatherers, ground honey/tree honey harvesters, carvers, etc. The investigation also extended to the traditional leaders of Nso and Oku who are in charge of the land tenure systems. The findings show that the Oku Mountain Forest is jointly owned by the Nso and Oku people. The Nso own the eastern half of the forest known as Ngongbaa Forest while the Oku own the western half, known as the Kilum Forest. The cordial relationship that existed between these people ensured the conservation of the forest. But the conflicts that later set in, especially due to the creation of the Kilum Mountain Forest Project in 1987 later changed to the Kilum Ijim Forest Project (KIFP) in 1992 sidelined the local communities which was contrary to the dispositions of the new Cameroon forest law enacted in 1994. Thus, the indigenous conservation practices became ig

关键词： Conflict Joint Management Shared Resources Ngongbaa Kilum Conservation

Statistical Study of the Geoeffectivity of Halo Coronal Mass Ejections Associated with X-Class Flares during Solar Cycles 23 and 24

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Open Journal of Applied Sciences 2024年第4期14卷 950-960页

作者： Younoussa Diakite Christian Zoundi M’Bi Kabore jean louis Zerbo Laboratoire de Chimie Analytique de Physique Spatiale et Energ&#233tique (L@CAPSE) Physics Department Universit&#233 Norbert Zongo Koudougou Burkina Faso Laboratoire de Maté riaux d&#8217H&#233liophysique et Environnement (LAMHE) Physics Department Universit&#233 Nazi Boni Bobo-Dioulasso Burkina Faso

By analysing a long series of data (1996-2019), we show that solar cycle 23 was more marked by violent solar flares and coronal mass ejections (CMEs) compared to solar cycle 24. In particular, the halo coronal mass ejections associated with X-class flares appear to be among the most energetic events in solar activity given the size of the flares, the speed of the CMEs and the intense geomagnetic storms they produce. Out of eighty-six (86) X-class halo CMEs, thirty-seven (37) or 43% are highly geoeffective;twenty-four (24) or approximately 28% are moderately geoeffective and twenty-five (25) or 29% are not geoeffective. Over the two solar cycles (1996 to 2019), 71% of storms were geoeffective and 29% were not. For solar cycle 23, about 78% of storms were geoeffective, while for solar cycle 24, about 56% were geoeffective. For the statistical study based on speed, 85 halo CMEs associated with X-class flares were selected because the CME of 6 December 2006 has no recorded speed value. For both solar cycles, 75.29% of the halo CMEs associated with X-class flares have a speed greater than 1000 km/s. The study showed that 42.18% of halo (X) CMEs with speeds above 1000 km/s could cause intense geomagnetic disturbances. These results show the contribution (in terms of speed) of each class of halo (X) CMEs to the perturbation of the Earth’s magnetic field. Coronal mass ejections then become one of the key indicators of solar activity, especially as they affect the Earth.

关键词： CME Halo (X) Geoeffectivity Geomagnetic Storm Solar Flare Solar Cycle

Lateral ring compression test applied to a small caliber steel jacket:Identification of a constitutive model

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Defence Technology（防务技术） 2024年第6期36卷 133-148页

作者： Yann Coget Yael Demarty Christophe Czarnota Anthony Bracq jean-Sebastien Brest Alexis Rusinek French-German Research Institute of Saint-louis 5 Rue Du General Cassagnou68300 Saint-LouisFrance Laboratoire d'Etude des Microstructures et de Mecanique des Materiaux(LEM3) CNRSUniversite de LorraineArts&Metiers ParisTechF-57000 MetzFrance

The evolution of threats and scenarios requires continuous performance improvements of ballistic protections for armed *** a modeling point of view,it is necessary to use sufficiently precise material behavior models to accurately describe the phenomena observed during the impact of a projectile on a protective *** this context,the goal of this paper is to characterize the behavior of a small caliber steel jacket by combining experimental and numerical *** experimental method is based on the lateral compression of ring specimens directly machined from the thin and small *** speeds and temperatures are considered in a quasi-static regime in order to reveal the strain rate and temperature dependencies of the tested *** Finite Element Updating Method(FEMU)is *** results are coupled with an inverse optimization method and a finite element numerical model in order to determine the parameters of a constitutive model representative of the jacket *** of the present model are verified against experimental results and a parametric study as well as a discussion on the identified material parameters are *** results indicate that the strain hardening parameter can be neglected and the behavior of the thin steel jacket can be described by a modeling without strain hardening sensitivity.

关键词： Full metal jacket ammunition Lateral ring compression Inverse identification Numerical simulation

Molecular Characterization of Gastrointestinal Stromal Tumors (Gist) and Contribution of Immunohistochemistry in Congolese from Kinshasa

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Open Journal of Gastroenterology 2024年第4期14卷 109-116页

作者： Rive Lukuaku Jérémie Okumadi Fabrice Bokambandja Andy Mbangama Vincent Mbatu Georges Mvumbi jean-louis Mumbere David Azako Serge Pezo Dieudonné Mvumbi Faculty of Medicine Bel Campus Technological University Kinshasa DR Congo Department of Anatomy and Pathological Cytology University Clinics of Kinshasa Kinshasa DR Congo Department of Gyneco-Obstetrics University Clinics of Kinshasa Kinshasa DR Congo Molecular Biology Department Faculty of Medicine University of Kinshasa Kinshasa DR Congo Institute of Medical Immunology Free University of Brussels Ixelles Belgium

Introduction: The differentiation of digestive tumors very often requires the use of techniques currently not widely in use in the Democratic Republic of Congo (DRC), such as immunohistochemistry. This is perfectly verified for GISTs whose precise, or at least highly certain, diagnosis can only be made using immunohistochemical markers. This underuse of these techniques due to lack of equipment and human skills explains the limited epidemiological data available to date, thus leading to untargeted and too often late treatment of patients. Research question: What contribution can immunohistochemical markers make to the diagnosis of digestive tract tumours? Objective: Discuss the contribution of immunohistochemical markers in the diagnosis of GIST and provide basic data on the epidemiology of these nosological entities in Kinshasa. Methodology: This was a retrospective study carried out at the LEBOMA private anatomy and pathological cytology centre. The main inclusion criterion was any digestive tract block or slide whose diagnosis of GIST had been requalified after review by at least 2 pathologists. An immuhistochemical study was performed using an automated technique (with a Ventana XT machine) using a panel of antibodies: CD-117 and DOG-1 which are listed in the literature as strongly correlated with the occurrence of GIST, all slides were made at Hj Hospital using an OLYMPUS BX41 co-observation microscope. Results: Of 601 cases of digestive tumors recorded during the concerned period, 32 (5.32%) concerned GIST. This prevalence was confirmed by our immunohistochemical results where the expression of CD117 and that of DOG-1 were positive in 90.6% and 100% of cases which prevalence is high compared with the worldwide prevalence according to the literature, respectively. The distribution of the patients concerned was made with a sex ratio of 1.6 women/men with a median age of 53 years. Most cases (81%) had a gastric location and were fusiform GISTs. Conclusion: Gastro

关键词： Digestive Tumors GIST Immunohistochemistry CD117 DOG-1

Phytochemical Analysis and Antioxidant Activity of Aqueous and Hydroethanolic Extracts from Three Anticancerous Fabaceae of Northern Cameroon Pharmacopoeia

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Journal of Biosciences and Medicines 2024年第6期12卷 19-32页

作者： Halmata Mohamadou Landry Lienou Lienou Richard Simo Tagne Herve Pabamé Kada Elisee Libert Enyengue Embolo Grace Kembaou Nganwa jean louis Oyono Essame Piere Michel Dongmo Jazet Anatomy and Cytology Pathology Laboratory Institute of Medical Research and Medicinal Plants Studies (IMPM) Yaound Cameroon Department of Biochemistry Faculty of Science University of Douala Douala Cameroon Department of Biomedical Sciences University of Ngaoundere Ngaoundere Cameroon General Hospital of Garoua (HGG) Garoua Cameroon Anatomo-Cytopathology Department of Biological Sciences Faculty of Medicine and Pharmacy University of Douala Douala Cameroon

Background: Cancer continues to pose a significant threat to our society, representing one of the most pressing health concerns worldwide. This study aimed to evaluate the chemical composition and the antioxidant activity of aqueous and hydroethanolic extracts from Acacia nilotica (An), Bauhinia reticulate (Br), and Tamarindus indica (Ti) of Fabaceae family, traditionally used in Northern Cameroon for cancer treatment. Methods: The phytochemical screening of the three plants was conducted using conventional colorimetric methods, followed by the measurement of total phenol content, flavonoids, and tannins. The antiradical and antioxidant activities of both plant extracts were assessed through FRAP, ABTS, and DPPH methods. A principal components analysis was employed to correlate the quantities of the evaluated secondary metabolites with the activities. Results: Both types of extracts from the three plants contain alkaloids, saponins, flavonoids, phenolic compounds, tannins, glycosides, terpenoids, coumarins, anthocyanins, and anthraquinones. The aqueous extracts of Br and An are significantly richer (p Conclusion: The three Fabaceae plants from northern Cameroon, prepared in different solvents, can be utilized for their antiradical properties in cancer treatment.

关键词： Cancer Antioxidant Fabaceae Phenolic Compounds Aqueous Extract Hydroethanolic Extract

Comparative Study of Solar PV Power Plant Dimensionnement Connected to Network Based on Monofacial and Bifacial Modules

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Journal of Environmental Science and Engineering(A) 2024年第1期13卷 36-44页

作者： DJOSSOU Ayihaou Armand VODOUNNOU Edmond Claude FANNOU jean louis Comlan DANSOU MidokpêRomuald SEMASSOU Guy Clarence HOUNGAN Comlan Aristide GUIDI Tognon Clotilde Thierno Amadou Barry Laboratory of Processes and Technological Innovation(LaPIT)/National Higher Institute of Industrial Technology(INSTI)of Lokossa/UNSTIM PB 133-Lokossa(Benin) Laboratory of Energetics and Applied Mechanics(LEMA)/Polytechnic School of Abomey-Calavi(EPAC)/UAC 01 PB 2009-Cotonou(Benin) National Higher School of Energy and Process Engineering(ENSGEP)of Abomey/UNSTIM National Higher School of Technical Education(ENSET)of Lokossa/UNSTIM 不详

This article presents the results of comparative study of two PV solar modules technologies,namely monofacial and *** study main objective is to identify conditions and parameters that make it possible to obtain better energy and economic efficiency from one or other of two *** study reason lies in revival observed on bifacial module in recent years where all the major manufacturers of PV solar panels are developing them where in a few years,this technology risks being at the same price as the monofacial solar panel with better *** indicator used is energy levelized cost(LCOE)which is function technology type,energy productivity,annual investment and operation *** achieve this,a 3.685 MWc solar PV power plant was dimensioned and simulated under Matlab for a 3.5 ha site with a 2,320,740,602 FCFA budget for monofacial installation,against 1,925,188,640 FCFA for 2.73 MWc bifacial *** LCOE comparative analysis of two technologies calculated over a period of 25 years,showed that plant with bifacial panels is more beneficial if bifacial gain is greater than 9%.It has further been found that it is possible to gain up to 40%of invested cost if bifacial gain reaches 45%.Finally,a loss of about 10%of invested cost could be recorded if bifacial gain is less than 9%.

关键词： Solar PV power plant Sizing Monofacial panels Bifacial panels LCOE.

Supervised Learning Method: Critical Analysis and Updating of Cubing Rate Formulas for Determining Bark Masses of Prunus africana (Hook. f.) Kalkman (Rosaceae) in Cameroon

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Open Journal of Forestry 2024年第3期14卷 346-368页

作者： Armand Ndedy Bile Alain Mpouam Benoit Fouadjio Lorette Guedeu Kambale Muhesi Steve Tassiamba Paulette Kouam Eric Wete Marius Ela Michèle Yimga Joseph Ambara louis Aimé Fono jean Lagarde Betti Department of Plant Biology Faculty of Science The University of Douala Douala Cameroon Department of Wood and Forest Sciences ISABEE University of Bertoua Bertoua Cameroon Department of Water and Forests Higher Institute of Agronomic Veterinary and Forestry Studies of Butembo Butembo Democratic Republic of Congo Department of Forestry Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon Department of Biology and Plant Faculty of Sciences University of Maroua Maroua Cameroon Deutsche Gresellschaft fur Internationale Zusammenarbeit GmbH (GIZ) Bertoua Cameroon Department of Mathematics and Computer Science Faculty of Science The University of Douala Douala Cameroon

The stem barks of Prunus africana are used in the treatment of the benign prostate. Cameroon is one of the important exporters of the barks. Despite the important measures adopted in Cameroon for sustaining its harvesting, some many chalenges still remain. The objective of this work is to refine the forest management parameters in relation to P. africana in the regions of Adamaoua and the South-West by developing a volume rate which makes it possible to estimate the production for a new stem. The work took place in two phases: in the South-West in 2010 and in Adamaoua in 2011. Data collection used the semi-direct method, while the cubing equation was deduced by the multiple linear regression method. Two models for volume estimation and three models for mass prediction were developed. The predictive parameters retained are diameter, height of the bole and thickness of the bark. Results show that the average mass of the dry bark for a given P. africana tree species is 27.55 ± 14.44 kg and this varies according to the site. The strong adjusted coefficient of determination (adjusted R2) observed illustrates the reliability of the proposed models. These models provide a reliable tool that can be adopted as a standard in Cameroon for P. africana.

关键词： Prunus africana Prostate Quota Mass Model Sustainable Management

Machine learning methods to assist energy system optimization

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建筑节能 2019年第6期47卷 87-87页

作者： A.T.D.Perera P.U.Wickramasinghe Vahid M.Nik jean-louis scartezzini 侯恩哲

(1) Machine learning methods to assist energy system optimization,by ***,***,Vahid ***,jean-louis scartezzini,Pages 191-205 Abstract: This study evaluates the potential of supervised and transfer learning techniques to assist energy system optimization.A surrogate model is developed with the support of a supervised learning technique (by using artificial neural network) in order to bypass computationally intensive Actual Engineering Model (AEM).Eight different neural network architectures are considered in the process of developing the surrogate ***,a hybrid optimization algorithm (HOA) is developed combining Surrogate and AEM in order to speed up the optimization process while maintaining the *** optimization is conducted considering Net Present Value and Grid Integration level as the objective *** learning is used to adapt the surrogate model (trained using supervised learning technique) for different scenarios where solar energy potential,wind speed and energy demand are notably *** reveal that the surrogate model can reach to Pareto solutions with a higher accuracy when grid interactions are above 10 %(with reasonable differences in the decision space variables).HOA can reach to Pareto solutions (similar to the solutions obtained using AEM) around 17 times faster than *** Surrogate Models developed using Transfer Learning (SMTL) shows a similar *** combined with the optimization algorithm can predict Pareto fronts efficiently even when there are significant changes in the initial ***,STML can be used along with the HOA,which reduces the computational time required for energy system optimization by 84 %.Such a significant reduction in computational time enables the approach to be used for energy system optimization at regional or national scale.

关键词： Distributed energy systems Supervised learning Transfer-learning Multi-objective optimization

Multiscale Analysis of Semilinear Damped Stochastic Wave Equations

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Acta Mathematica Sinica,English Series 2023年第7期39卷 1305-1331页

作者： Aurelien FOUETIO Gabriel NGUETSENG jean louis WOUKENG Department of Mathematics Higher Teacher Training CollegeUniversity of NgaoundereP.O.Box 652BertouaCameroon Department of Mathematics University of Yaounde IP.O.Box 812YaoundeCameroon Department of Mathematics and Computer Science University of DschangP.O.Box 67DschangCameroon

In this paper we proceed with the multiscale analysis of semilinear damped stochastic wave motions. The analysis is made by combining the well-known sigma convergence method with its stochastic counterpart, associated to some compactness results such as the Prokhorov and Skorokhod theorems. We derive the equivalent model, which is of the same type as the micro-model. One of the novelties of the work is that the corrector problem is solved in the classical sense of distributions,thereby allowing numerical computations of the homogenized coefficients.

关键词： Hyperbolic stochastic equations Wiener Process sigma convergence tightness of probability measures