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Performance Improvement in Manufacturing Shop Floor Operations of Developing Countries Based on Three Characteristics of Information Flow

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Journal of Computer and Communications 2022年第3期10卷 46-65页

作者： Joseph Voufo André Marie Mbakop Florent Biyeme Rolland Djomi Pélagie Flore Nanfack Temgoua jean raymond lucien meva’a National Advanced School of Engineering of Yaoundé (NASEY) Yaoundé Cameroon Laboratory of Civil and Mechanical Engineering Yaoundé Cameroon Department of Mechanical and Industrial Engineering Yaoundé Cameroon Ministry of Scientific Research and Innovation National Committee for Development of Technologies Yaoundé Cameroon

The management of information flow for production improvement has always been a target in the research. In this paper, the focus is on the analysis model of the characteristics of information flow in shop floor operations based on the influence that dimension (support or medium), direction and the quality information flow have on the value of information flow using machine learning classification algorithms. The obtained results of classification algorithms used to analyze the value of information flow are Decision Trees (DT) and Random Forest (RF) with a score of 0.99% and the mean absolute error of 0.005. The results also show that the management of information flow using DT or RF shows that, the dimension of information such as digital information has the greatest value of information flow in shop floor operations when the shop floor is totally digitalized. Direction of information flow does not have any great influence on shop floor operations processes when the operations processes are digitalized or done by operators as machines.

关键词： Developing Countries Information Flow Characteristics Machine Learning Shop Floor Operations Value of Information Flow

Mechanical Characterization of Rhecktophyllum Camerunense (RC) Fiber Reinforced Concrete

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Journal of Modern Physics 2023年第8期14卷 20-32页

作者： jean Calvin Bidoung Nicolas Stéphane Nyobe Mey Mahamat Imar lucien meva’a National Advanced School of Engineering Yaounde Cameroon Local Materials Promotion Authority Yaounde Cameroon

This work presents the development and mechanical characterization of a concrete reinforced with plant fiber extracted from Rhecktophyllum Camerunense (RC), a plant found in the regions of Center and South Cameroon. A comparative study between ordinary concrete and concrete reinforced with RC fiber at different percentages (0.1%, 0.2% and 0.3%) was carried out. The mechanical characterization of the material consisted in studying the flexural, compressive and splitting tensile strength by using cylindrical specimens of dimensions 160 × 320 in accordance with standards EN 12390-3 and EN 12390-6. The study of the mechanical properties was completed by the three-point bending test using prismatic test specimens of dimension 40 × 40 × 160 made according to the EN 196 standard. It emerges from this work that the addition of RC fiber improves the mechanical properties of concrete up to 0.2% with a peak at 0.1% of fiber corresponding to respective increases of 9%, 16% and 6% of the values of mechanical resistance to compression, flexion and tension after 28 days. From 0.3% of fiber, the values of the mechanical characteristics of the composite drop to values lower than those of ordinary concrete. The density reduction rate at 28 days is about 10% compared to the mass of ordinary concrete. These results allow us to conclude that the RC fiber could be valorized for the production of lightweight concrete.

关键词： Reinforced Concrete RC Fiber Mechanical Properties Lightweight Concrete

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Physicochemical and Thermal Characterization of Dura Palm Kernel Powder as a Load for Polymers: Case of Polyvinyl Chloride

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Journal of Materials Science and Chemical Engineering 2018年第6期6卷 1-18页

作者： Rolland Djomi lucien jean raymond meva’a jean Nganhou Gérard Mbobda Abel Emmanuel Njom Yves Didier Modtegue Bampel jean-Bosco Saha Tchinda Civil and Mechanical Engineering Laboratory National Advanced School of Engineering University of Yaounde I Yaounde Cameroon Research Unit for Macromolecular Chemistry Applied Inorganic Chemistry Laboratory Faculty of Science University of Yaounde I Yaounde Cameroon

This work presents the physical and thermal characterization of the dura palm kernel powder of Cameroon for their use as fillers for polymers composites. The powders of palm kernel were obtained using a percussion grinder mill with an industrial microniser which allowed obtaining a powder less than 50 μm with an apparent density between 0,505 ≤ ρ ≤ 0,680 g/cm3 at 1.56 of relative humidity. The infrared of the powder of palm kernel shows the presence of phenols groups with a large band around 3341 cm-1, -C-H at 2917.02 cm-1 and -C-O at 1040 cm-1 as the main peaks. The polyvinyl chloride of infrared obtained shows the presence of -C-Cl, -CH2 and CH as the mains peaks. The infrared of 12.5% of palm kernel powder with polyvinyl chloride shows an increase of the CH2 and CH bonds and a decrease of the -OH bonds. Thermogravimetric analysis and differential scanning calorimetric analysis of powders, polyvinyl chloride and mixture showed that the mixing powders are intermediate between the polyvinyl chloride and palm kernel powder. The powder decreased the phase temperatures of the mixture from 98.58℃ to 95℃ for the glass transition temperature and from 515℃ to 459℃ for the crystallization temperature. The thermogravimetric curves of palm kernel powder and polyvinyl chloride have showed that these materials lose their different masses in three different phases, and the one of composite (mixture of polyvinyl chloride with 12.5% of palm kernel powder) in two different phases.

关键词： Dura Palm Kernel Shell Load for Polymers Thermogravimetric Analysis DSC

Micro Hydro Power Plant for Sustainable Energy in Rural Electrification: A Case Study in Cameroon

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Journal of Power and Energy Engineering 2023年第6期11卷 34-43页

作者： Elie Bertrand Kengne Signe Lyse Vanessa Ngansop Tchatchouang Pierre Pokem Paule Alexandrine Ekoube lucien meva’a jean Nganhou Center of Research on Renewable Energy Institute for Geological and Mining Research Yaoundé Cameroon National Advanced School of Engineering University of Yaoundé 1 Yaoundé Cameroon

The state of Cameroon, faced with the situation the electricity deficits, is promoting the development of renewable energies in general and to meet rural electrification needs in particular. The purpose of this work is to study the feasibility of the MHP of Batcheu, to show its contribution to sustainable development in this locality and to prove that it is a profitable project. After study, it appears that the waterfall of Batcheu is favourable to the establishment of a MHP with an installed power of 260 kW with an operating diagram corresponding to a Francis turbine. Given that it is a renewable energy that can supply more than 800 households in rural areas, its contribution to sustainable development is obvious. Its investment cost is estimated at 171,465,396 FCFA. It is a profitable project with a payback time of 7 years and 2 months.

关键词： Micro Hydro Power Sustainable Development Rural Electrification

Physico-Chemical and Thermal Characterization of a Lignocellulosic Fiber, Extracted from the Bast of <i>Cola lepidota</i>Stem

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Journal of Minerals and Materials Characterization and Engineering 2020年第5期8卷 377-392页

作者： Ndoumou Belinga Rémy Legrand meva’a lucien Ouagne Pierre Betene Ebanda Fabien Noah Pierre Marcel Atangana Ateba jean Laboratoire de Mécanique (LME) UFD SI Université de Douala Douala Cameroun Laboratoire d’Ingénierie Civile et Mécanique Université de Yaoundé I Yaoundé Cameroun Laboratoire Génie de Production (LGP) ENI de Tarbes Tarbes France

In this research work, fiber extracted from the bark of Cola lepidota (CL) plant, grown in the flora of Southern part of Cameroon, was investigated for composites reinforcement. The investigation was carried via evaluation of water absorption capacity, moisture content, real density, porosity, chemical composition, chemical structure and thermal behaviour. It was discovered that the new fiber has relatively low moisture content and water absorption capacity similar to those of other investigated natural fibers such as flax, sisal, coconut, hemp and jute. Its porosity was found appropriate for composite production and the fiber was found to be thermally stable up to 230°C, with maximum degradation temperature of 325°C. The main constituents of the fibre include cellulose, hemicellulose and lignin. In conclusion, based on the properties investigated, this fiber is considered suitable for composite manufacture.

关键词： Cola lepidota Fiber Thermal Stability Physico-Chemical Characteristics FTIR-ATR Liber Stem

Formal modelling of list based dynamic memory allocators

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Science China(Information Sciences) 2018年第12期61卷 81-96页

作者： Bin FANG Mihaela SIGHIREANU Geguang PU Wen SU jean-raymond ABRIAL Mengfei YANG Lei QIAO Shanghai Key Laboratory of Trustworthy Computing East China Normal University IRIF University Paris Diderot and CNRS School of Computer Engineering and Science Shanghai University

Existing implementations of dynamic memory allocators(DMA) employ a large spectrum of policies and techniques. The formal specifications of these techniques are quite complicated in isolation and very complex when combined. Therefore, the formal reasoning on a specific DMA implementation is difficult for automatic tools and mostly single-use. This paper proposes a solution to this problem by providing formal models for a full class of DMA, the class using various kinds of lists to manage the memory blocks controlled by the DMA. To obtain reusable formal models and tractable formal reasoning, we organise these models in a hierarchy ranked by refinement relations. We prove the soundness of models and the refinement relations using the modeling framework Event-B and the theorem prover Rodin. We demonstrate that our hierarchy is a basis for an algorithm theory for list based DMA: it abstracts various existing implementations of DMA and leads to new DMA implementations. The applications of this formalisation include model-based code generation, testing, and static analysis.

关键词： dynamic memory allocators formal methods refinement Event-B Rodin model-based design

Infrared spectroscopy analyses of air-CH_4 or air-CO gas flows interacting with polycrystalline CeO_2, La_2O_3 and Lu_2O_3 oxides

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Journal of Rare Earths 2012年第8期30卷 835-841页

作者： Bahcine BAKIZ Lamia BOURJA Abdeljalil BENLHACHEMI Frédéric GUINNETON Madjid ARAB jean-raymond GAVARRI Institute Materials Microelectronics & Nanosciences of Provence UMR CNRS 6242 University SOUTH Toulon-Var Laboratory Materials & Environment Faculty of Sciences University Ibn Zohr

A comparative study of reactivity between air-CH4 or air-CO gas flows and CeO2, La2O3 and Lu2O3 rare earth oxides was per- formed using Fourier transform infrared spectroscopy analyses of CO2 gas resulted from the conversion of CH4 or CO gases. Polyerystalline samples of CeO2, La2O3 and Lu2O3 were first prepared by specific precipitation methods followed by low temperature calcination process. In the case of Lu2O3 oxide, a new specific route was proposed. Crystallite dimensions were determined by X-ray diffraction and transmission electron microscopy analyses. Morphologies were characterized using scanning electron microscopy. Specific surface areas were determined from Bnmauer-Emmett-Teller （BET） technique. Using infrared spectroscopy analyses, the conversion rates of CH4 or CO into CO2 were de- termined from the evolutions of CO2 vibrational band intensities, as a function of time and temperature. It was dearly established that, despite its low specific surface, the Lu2O3 oxide presented the highest capacity of conversion of CH4 or CO into CO2.

关键词： lutetium oxide rare earth oxides elaboration gas solid interactions infrared spectroscopy

Antilocalization sensing of interactions between two-dimensional electrons and surface species

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Chinese Science Bulletin 2014年第2期59卷 133-137页

作者： Yao Zhang Victoria Soghomonian raymond L.Kallaher jean J.Heremans Department of Physics Virginia Tech Blacksburg

We apply antilocalization measurements to experimentally study the interactions and exchange between InAs surface accumulation electrons and local magnetic moments of the rare earth ions Sm3?,Gd3?,Ho3?,and Dy3?,of the transition metal ions Ni2?,Co2?,and Fe3?,and of Fe3O4nanoparticles and Fe3?-phthalocyanine deposited on the *** influence of the deposited species on the surface electrons is observed through the changes in the spin–orbit scattering and magnetic spin-flip scattering rates,which carry information about magnetic *** indicate a temperature-dependent magnetic spin-flip scattering for Ho3?,Dy3?,Ni2?,and Co2?.Concerning the spin–orbit scattering rate,we observe an increase,except for the cases of Ni2?,Fe3?,Fe3O4nanoparticles and Fe3?-*** also observe an increase in SO scattering in another system where we study the interactions of Au nanoparticles and ferromagnetic Co0.6Fe0.4nanopillars and an In0.53Ga0.47As quantum *** results are analyzed and compared to theoretical *** method provides a controlled way to probe the quantum properties of two-dimensional electron systems,either on the surface of InAs or in a quantum well.

关键词：二维电子系统磁相互作用表面 Fe304 金纳米粒子物质感应过渡金属离子

The ecology of sexual dimorphism in size and shape of the freshwater blenny Salaria fluviatilis

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Current Zoology 2018年第2期64卷 183-191页

作者： Martin LAPORTE Patrick BERREBI Julien CLAUDE Dolors VINYOLES Quim Pou-RoVIRA jean-Claude raymond Pierre MAGNAN lnstitut des Sciences de I'Evolution de Montpellier (ISEM) UMR 5554 UM2-CNRS-IRD Universite de Montpellier II CC065 Place E. Bataillon Montpellier Cedex 534095 France Departement de Biologie Institut de Biologie Integrative et des Systemes (IBIS) Universite Laval Quebec Quebec City Canada G1V 0A6 Department of Evolutionary Biology Ecology and Environmental Sciences Faculty of Biology University of Barcelona Avda. Diagonal 643 Barcelona 08028 Spain Sorello estudis al medi aquatic Placa St. Pere 15 Baixos 17007 Girona Spain Office National de I'Eau et des Milieux Aquatiques (0NEMA) Unite Specialisee Milieux Lacustres Pisciculture de Rives 13 Quai de Rives Thonon-les-Bains 74200 France Centre de recherche sur les interactions bassins versants-ecosystemes aquatiques (RIVE) Universite du Quebec a Trois-Rivieres C. P. 500 Trois-Rivieres Quebec City Canada G9A 5H7

Sexual selection is considered the major cause of sexual dimorphism, but recent observations suggest that natural selection may play a more important role in the evolution of sex differentiation than previously recognized. Therefore, studying the trade-offs between natural selection and sexual selection is crucial to a better understanding of the ecology underlying the evolution of sexual dimorphism. The freshwater blenny Salaria fluviatilis, a fish inhabiting lakes and rivers around the Mediterranean Sea, displays strong sexual dimorphism in size, shape, and behavior （i.e., larger body and head size for males and higher swimming requirements for females during the reproductive period）. We tested for differences in sexual dimorphism in size and shape between the populations from lake and river habitats with the goal of identifying the trade-offs between natural and sexual se- lection that underlie variations in sexual dimorphism in this species. Our results show i） differences in sexual size dimorphism （SSizeD） in accordance to Rensch＇s rule （i.e., larger individuals in rivers associated with higher SSizeD）, and ii） a decrease in shape differentiation between males and fe- males in lake populations. Together, this suggests that the different environmental conditions between lake and river habitats （e.g., resource limitations, predation pressure, water velocity） affect the relative importance of sexual selection in the display of sexual dimorphism within the species. This study highlights the importance of considering the environmental conditions to which populations are exposed to better understand the ecology underlying the evolution of sexual dimorphism.

关键词： evolutionary ecology geometric morphometrics phenotype-environment interaction Rensch's rule sexual dimorphism.