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Search Results: 1 - 10 of 12 matches for " Danwe Raidandi "
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Simulation of a DI Diesel Engine Performance Fuelled on Biodiesel Using a Semi-Empirical 0D Model  [PDF]
Claude Valery Ngayihi Abbe, Robert Nzengwa, Raidandi Danwe, Zacharie Merlin Ayissi, Marcel Obounou
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.510066
Abstract:

Diesel engines have proven over the years important in terms of efficiency and fuel consumption to power generation ratio. Many research works show the potential of biodiesel as a substitute for conventional gasoil. Mainly, previous and recent researches have focused on experimental investigation of diesel engine performance fuelled by biodiesel. Researches on the mathematical description of diesel engine process running on biodiesel are scarce, and mostly about chemical and thermodynamic description of the combustion process of biodiesel rather than performance studies. This work describes a numerical investigation on the performance analysis of a diesel engine fuelled by palm oil biodiesel. The numerical investigation was made using a semi empirical 0D model based on Wiebe’s and Watson’s model which was implemented via the open access numerical calculation software Scilab. The model was validated first by comparing with experimental pressure and performance data of a one cylinder engine at rated speed and secondly by comparing with a six cylinders engine performance data at various crankshaft rotational speeds. Simulations were then made to analyze the engine performance when running on biodiesel. The calculations were made at constant combustion duration and constant coefficient of excess air. Results showed that the model matches the overall experimental data, such as the power output and peak cylinder pressure. The ignition delay was somehow underestimated by the model for the first experiment, which caused a slight gap on in cylinder pressure curve, whereas it predicted the average ignition delay fairly well for the second set of validation. The simulations of engine performance when running on biodiesel confirmed results obtained in previous experimental researches on biodiesel. The model will be further investigated for engine control when shifting to biodiesel fuel.

Characteristics and Mechanicals Potentials of Wood Adhesives Manufactured with Grasses’ Lignins  [PDF]
Lionel Tapsia Karga, Danwe Raidandi, Noel Konai, Antonio Pizzi, Lucien Meva’a
Journal of Materials Science and Chemical Engineering (MSCE) , 2019, DOI: 10.4236/msce.2019.71004
Abstract: In order to manufacture environmentally friendly particle boards and enhance local resources, the lignins of Sorghum bicolor and Andropogon gayanus characterized using RMN 13C and MALDI TOF have the same structures. They contents Guaiacyl (G), Syringyl (S), p-hydroxyphenylpropane (H) and functional groups of phenols, flavonoids and secondary alcohols. The total phenol content determinated using Folin-Ciocalteu reagent is respectively 20.97 and 15.42 mg eqgallic acid/g of extract. The power of their adhesives is different. The Internal Bond (IB) of particleboards manufactured with these adhesives are respectively 0.37 MPa and 0.41 MPa. These lignins can be used as antioxydants.
Modeling the wait time of a hierarchical system: Case study of an Internal Medicine unit
L. MEVA’A,,R. DANWE,J. NGANHOU
International Journal of Engineering and Technology , 2011,
Abstract: All, such as industrial production (Manufacturing companies), health units are hierarchical at the level of organization. This arrangement permits them to response efficiently to an event in occurrence, such as a patient whom appropriate care has to be dispensed. The quick reaction of the medical unit when faced with a problem is not only an indicator of its reactivity, but also an indicator of its performance.In this article, we propose to model the reaction of a medical unit in relationship to parameters, notably the reference periods of the different levels at which decisions are made. We define and express subsequently, the wait times which is a source of delay in the treatment process of a patient from when he arrives. Then, we propose an algorithm which minimizes the wait time.
A tool to determine the quantity of components needed taking into consideration reject: application in a small agro-company
L. MEVA'A,,R. DANWE,,I. BINDZI
International Journal of Engineering and Technology , 2011,
Abstract: This project presents the realization of a tool to determine the raw material needs for small companies in the agricultural sector in Cameroon. The objective is to; eliminate stocking perishable raw materials by ordering the right quantities and just on time too. To attain this objective, we integrate technical and commercial information as well as consider damages (loss) in input and end products. We then apply this tool to a small enterprise that producesfruit juice.
Expression of Maintenance Down Time as a function of the management mode of the failure
L. MEVAa€?A,,R. DANWE,,T. BEDA
International Journal of Engineering Science and Technology , 2011,
Abstract: In production, machine Down Time imputable to maintenance is a permanent preoccupation of services responsible for the proper functioning of production tool. It influences notably the performanceof the enterprise and thus, is the main objective of some companies. In this article, we are proposing an expression of the down time of a production chain, resulting from the apparition of a breakdown. Theparticularity of our approach is to take into account on one part, the hierarchical structure of the maintenance workshop and on the other part, the management mode of the breakdown in the correctionprocess by integrating periodicity in the decision making. Next, we identify the total inactive maintenance time which we wish to reduce following a reduction algorithm.
Model and Reduction of Inactive Times in a Maintenance Workshop Following a Diagnostic Error
L. Meva'a,R. Danwe,T. Beda
Engineering, Technology & Applied Science Research , 2011,
Abstract: The majority of maintenance workshops in manufacturing factories are hierarchical. This arrangement permits quick response in advent of a breakdown. Reaction of the maintenance workshop is done by evaluating the characteristics of the breakdown. In effect, a diagnostic error at a given level of the process of decision making delays the restoration of normal operating state. The consequences are not just financial loses, but loss in customers’ satisfaction as well. The goal of this paper is to model the inactive time of a maintenance workshop in case that an unpredicted catalectic breakdown has occurred and a diagnostic error has also occurred at a certain level of decision-making, during the treatment process of the breakdown. We show that the expression for the inactive times obtained, is depended only on the characteristics of the workshop. Next, we propose a method to reduce the inactive times.
DimCuve : An Automatic Tool for the Optimisation of the Design and Realization of a Raw Palm oil Storage Tank
R. DANWE,,L. MEVA’A,J. DIKWA,,A. NGUIDJOL
International Journal of Engineering and Technology , 2010,
Abstract: This paper concerns the study of the design and realization of a storage tank for raw palm oil. The main objective is to solve the problems of supply shortages of raw palm oil to stock-out to small and Medium Size Enterprises in Cameroon. We first of all look at the state-of-the-art of the design and realization of storage tanks, and then, and in the case of raw palm oil storage, we design an open cylindrical vertical tank with a conical roof supported by a ramework. We then proceed with the sizing of all the structural elements based on specially chosen mechanical criteria. We put in place software, DimCuve, to be used for the automatic sizing of storage tanks. The interest of this work is conclusive for enterprises of this sector.
NUMERICAL SIMULATION OF THE GEOMETRY OF LOGS FOR SAWING INDUSTRIES
R. DANWE,,I. BINDZI,,L. MEVA’A,,B. F. NOLA
International Journal of Engineering Science and Technology , 2011,
Abstract: Currently, the majority of wood sawing industries in Cameroun have as a concern the search for an optimization of the production. It is a question of having a good output matter during the cutting up. Thisproblem passes by knowledge of the geometry of the wood log, the strategies of cutting up and the quality of output. In this paper we develop a tool able to represent the log geometry with an aim at carrying out an optimal cutting up. We used representation by the analytical equations of the geometry of the external structure of the log ; that enables us to obtain an algorithm which helps to numerically generate the external structure of the wood.
Optimization of sawing in wood transformation primary industries
Ra?dandi Danwe,Isaac Bindzi,Lucien Meva'a
Journal of Industrial Engineering and Management , 2012, DOI: 10.3926/jiem.374
Abstract: Purpose: The loss of raw materials in wood cutting industries has reached high proportions (30 to 36% of volume yield, Ngolle Ngolle, 2009). The purpose of this paper is to solve the problem of optimising the production on the basis of the commercial value of the cuts. Design/methodology/approach: In order to tackle this problem, we started with the generalities on the exploitation and the primary conversion of wood in Cameroon. After that, we studied the various methods of cutting and the different products obtained. We then proceeded with the formulation of the log cutting optimisation problem based on a real shape model of the logs, objective of research works presented in (Danwé, Bindzi, Meva’a & Nola, 2011). We finally completed our work with the design and the presentation of a software package called cutting optimiser. Findings: We start by having some knowledge on the geometry of the logs, cutting strategies and classification of cuts. This classification enables us to determine the quality and quantity of the production, and to estimate the commercial value of the log. The solution to this problem then led to the design of a software package. Research limitations/implications: In this paper, the optimisation problem concerns problems where the objective function is non-explicit, the variables discreet, and the constraints non-explicit. Practical implications: The solution to this problem then led to the design of a software package to be used as a cutting optimiser. The automation of the cutting operation leads to an accelerated work and an increase in the volume of the cuts produced daily. Originality/value: This research is among the few to solve discrete optimization problems with constraints. Some constraints concerning the mechanical characteristics of the logs are taken into account. The constraints can equally be non-explicit. Moreover the market standards impose technological constraints which render the problem of optimisation even more complex.
Effect of Antiretroviral Therapy on Lipid Metabolism in HIV/AIDS Subjects in Cameroon
C. Danwe,G. Atchou,M. Nkam,J. Mbuagbaw
Journal of Medical Sciences , 2005,
Abstract: This study sets out to investigate the effect of anti-retroviral therapy on lipid metabolism in HIV/AIDS patients in Cameroon. A descriptive and prospective study was carried out on 16 HIV/AIDS individuals with CD4 counts of less than 200 cells mm-3 and on antiretroviral drugs. The various drug regimens included Nevirapine-Lamivudine-Stavudine and Efavirenz-Lamivudine-Stavudine/or Zidovudine. No patients were on protease inhibitors. All patients were monitored at baseline and then monthly thereafter for 3 months. A complete clinical examination and blood samples were respectively collected for total cholesterol, LDL-cholesterol, HDL- cholesterol, triglycerides, Apolipoproteins A1 (ApoA1) and B100 (ApoB100). Total cholesterol and LDL cholesterol levels increased significantly (p<0.05) with administration of the antiretroviral therapy. HDL cholesterol as well as ApoA1 levels was noted to rise significantly (p<0.05) with time, suggesting increased biosynthesis of HDL. On the other hand, triglycerides, ApoB100 and the total cholesterol/ HDL cholesterol ratio remained unaltered. The increase of total and LDL-cholesterols may serve as indicators for the risk of cardiovascular disease in HIV/AIDS patients on antiretroviral drugs. The biosynthesis of HDL lipoprotein could also be associated with antiretroviral therapy.
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