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Wyszukujesz frazę "Lemu, Hirpa G." wg kryterium: Autor

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    Wyświetlanie 1-6 z 6
    Tytuł:
    Design and modelling of a light duty trencher for local conditions
    Autorzy:
    Kajela, Delesa
    Lemu, Hirpa G
    Powiązania:
    https://bibliotekanauki.pl/articles/102743.pdf
    Data publikacji:
    2018
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    trencher
    ditch
    fundamental earth-moving equation (FEE)
    Evans’s theory
    trenching tooth
    stress analysis
    koparka
    rów
    podstawowe równanie ziemskie (FEE)
    teoria Evansa
    analiza naprężeń
    Opis:
    The adverse effect of using traditional equipment particularly in developing countries is that it is time and energy consuming, less productive, difficult and more manpower is required. Hence, it is necessary to design and produce low price, and simple machines that can narrow this gap. The objective of the project reported in this article is to design and model a light duty trencher that is used for trenching the ground or soil for making ditch, and used for agricultural, ground cabling, ground piping and drainage system. The designed machine trenches, maximum of 1 m depth, 30 cm width and has adjustable length. The working mechanism is fully hydraulic, and equipped with an engine of 12.7 hp, which provides suitable power for the pump that delivers 23 l/min at 1500 rpm to drive hydraulic motors and actuators.
    Źródło:
    Advances in Science and Technology. Research Journal; 2018, 12, 1; 303-311
    2299-8624
    Pojawia się w:
    Advances in Science and Technology. Research Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Solution approaches to differential equations of mechanical system dynamics: a case study of car suspension system
    Autorzy:
    Terefe, Tesfaye O.
    Lemu, Hirpa G
    Powiązania:
    https://bibliotekanauki.pl/articles/102050.pdf
    Data publikacji:
    2018
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    numerical method
    Euler method
    differential equation
    suspension system
    MATLAB
    mechanical system modeling
    metoda numeryczna
    Metoda Eulera
    równanie różniczkowe
    zawieszenie
    modelowanie układów mechanicznych
    Opis:
    Solution of a dynamic system is commonly demanding when analytical approaches are used. In order to solve numerically, describing the motion dynamics using differential equations is becoming indispensable. In this article, Newton’s second law of motion is used to derive the equation of motion the governing equation of the dynamic system. A quarter model of the suspension system of a car is used as a case and sinusoidal road profile input was considered for modeling. The state space representation was used to reduce the second order differential equation of the dynamic system of suspension model to the first order differential equation. Among the available numerical methods to solve differential equations, Euler method has been employed and the differential equation is coded MATLAB. The numerical result of the second degree of freedom, quarter suspension system demonstrated that the approach of using numerical solution to a differential equation of dynamic system is suitable to easily simulate and visualize the system performance.
    Źródło:
    Advances in Science and Technology. Research Journal; 2018, 12, 2; 266-273
    2299-8624
    Pojawia się w:
    Advances in Science and Technology. Research Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Design, Simulation and Production of Hydraulic Briquette Press for Metal Chips
    Autorzy:
    Kebede, Bisrat M.
    Lemu, Hirpa G
    Powiązania:
    https://bibliotekanauki.pl/articles/103011.pdf
    Data publikacji:
    2019
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    metal chips
    briquettes
    compacting machine
    chip conveyor
    computer aided design
    finite element analysis
    chip recycling
    wióry metalowe
    brykiety
    maszyna do zagęszczania
    przenośnik wiórów
    projektowanie wspomagane komputerowo
    analiza elementów skończonych
    recykling wiórów
    Opis:
    Removal of metal chips is involved in several industrial production processes that machine from casted parts by various operations such as turning, milling and drilling. In addition to the fact that the chips represent a treat to the environment, their storage requires a large surface area. The objective of the project reported in this article is to improve the current layout of a machining workshop aimed at minimizing the material handling cost, increasing operator safety, improving flexibility for operation, minimizing the overall cost and utilizing the available area. The research project focused on the compaction of metal chips briquette for simplicity of storage as well as handling and transportation of metal chips for Hibret Manufacturing and Machine Building Industry (HMMBI) factory. The machining process on CNC lathe and milling machines in this company produces 1500–2000 kg chips/month. An effective design of hydraulic briquette press is carried out by using a solid modelling tool and simulating the hydraulic circuit. The result of the designed machine was observed to address the stated problems of the company.
    Źródło:
    Advances in Science and Technology. Research Journal; 2019, 13, 2; 24-30
    2299-8624
    Pojawia się w:
    Advances in Science and Technology. Research Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of the Performance of Natural Fiber Reinforced Composites for Wind Turbine Blade Applications
    Autorzy:
    Batu, Temesgen
    Lemu, Hirpa G
    Sirhabizuh, Belete
    Powiązania:
    https://bibliotekanauki.pl/articles/102545.pdf
    Data publikacji:
    2020
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    natural fiber
    reinforced composites
    wind turbine blade
    Qblade
    włókno naturalne
    wzmocniony kompozyt
    łopatka turbiny wiatrowej
    Opis:
    The availability of some form of energy is essential for the human survival and social development. However, the way energy has been generated within the last century has brought forward the quest for the generation of energy without polluting the environment, which is nowadays considered to be the greatest global challenge. The materials used for wind turbine blades can be classified under this challenge of polluting the environment. One of the materials expected to reduce this problem is natural fiber reinforced composite (FRC). Thus, the focus of this paper was to evaluate the potential of different natural FRC materials for small wind turbine blade application. Eleven different natural fibers reinforced composite in epoxy resin were studied. A modified Halphin-Tsai semi-empirical model was used to compute the physical properties of the composites, since it has a good agreement with the experimental results. Stress, deformation, and weight of wind turbine blade under different loadings were analyzed aimed to search for a fiber type that may extend the life span of the blade. Finally, flap wise and edge wise, the longitudinal and torsional natural frequencies were computed numerically by using the finite element method in the Qblade software (QFEM) under different mode types and the effects were analysed. Upon comparing the results with a common composite material for wind turbine blade (E-glass/epoxy), it was observed that the selected natural fiber composites have equivalent and better mechanical performance. The environmental friendliness of natural fibers, i.e. biodegradability, constitutes their advantage as materials of wind turbine blades.
    Źródło:
    Advances in Science and Technology. Research Journal; 2020, 14, 2; 67-75
    2299-8624
    Pojawia się w:
    Advances in Science and Technology. Research Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Internal Corrosion Damage Mechanisms of the Underground Ferrous Water Pipelines
    Autorzy:
    Yeshanew, Desalegn A.
    Jiru, Moera G.
    Lemu, Hirpa G.
    Tolcha, Mesay A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2201765.pdf
    Data publikacji:
    2022
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    internal corrosion
    water pipes
    water physico-chemical analysis
    corrosion mechanisms
    corrosion mechanism
    Opis:
    Internal water pipe corrosion is a complicated problem due to the interaction of water quality parameters with pipe wall. This study presents investigations of internal pipe surface corrosion mechanisms related to water physicochemical. Samples of water and corrosion-damaged ductile cast iron (30+ years) and galvanized steel pipe (15-20 years) were collected at in-situ condition from Addis Ababa city water distribution system. Scanning electron microscopy and optical microscopy were used to examine the pipes' corrosion morphology and microstructures, respectively. Additionally, Mountains 9 surface analysis software was used for further pitting corrosion characterization.To identify the causes of internal pipe corrosion, water physicochemical analyses were conducted by using inoLab pH 7310P, DR 900, Palintest Photometer 7100, and Miero 800. Water physicochemical test indicates: CaCO3 is 77 - 215 ppm, pH is 7.05 – 7.86, total dissolved solids (TDS) is 84.10 -262.8 ppm, ClO2 is 0 – 0.5 ppm, and dissolved oxygen (80-81 ppb). From water test results, major causes of internal pipe corrosion damage mechanisms were identified as dissolved oxygen, CaCO3, TDS, ClO2,and resistivity of water which initiates a differential cell that accelerates pipe corrosion. Using Mountain 9 surface analysis software, corrosion morphology and pitting features were characterized. The outputs of this paper will be helpful for water distribution and buried infrastructure owners to investigate corrosion damage mechanisms at early stage. To manage corrosion mechanisms, water supply owners need to conduct frequent inspections, recording of pipe data, testing of water quality, periodic pipelines washing, and apply preventative maintenance.
    Źródło:
    Advances in Science and Technology. Research Journal; 2022, 16, 3; 111--123
    2299-8624
    Pojawia się w:
    Advances in Science and Technology. Research Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Kinematic Modeling and Analysis of a Walking Machine (Robot) Leg Mechanism on a Rough Terrain
    Autorzy:
    Terefe, Tesfaye O.
    Lemu, Hirpa G
    K/Mariam, Addisu
    Tuli, Tadele B.
    Powiązania:
    https://bibliotekanauki.pl/articles/102737.pdf
    Data publikacji:
    2019
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    walking machine
    walking robot
    kinematic analysis
    motion analysis
    Denavit-Hartenberg
    rough terrain
    maszyna krocząca
    robot kroczący
    analiza kinematyczna
    analiza ruchu
    nierówny teren
    Opis:
    Many manmade machines and mechanisms, including robots, function based on the concept of nature-inspired design, so that they can perform their intended duties by mimicking the working mechanisms of animals and insects. Accordingly, walking machines (robots) use wheels and tracks to cross rough terrain efficiently and in a more stable way than conventional robots. Legged walking robots in particular remain in a discontinuous contact with the ground that provides them with the capability to select routes to avoid obstacles or holes. This article reports a study conducted on kinematic modelling and analysis of a walking machine (robot) leg mechanism that can operate on rough terrain. Its kinematic mechanisms were analyzed using the Denavit-Hartenberg (DH) convention approach. Symbolic computations are also implemented to parametrically optimize the motion parameters of the robot leg mechanism. The equation of motion was derived from the dynamic analysis using the Euler-Lagrange method which involves kinetic and potential energy expressions. In order to validate the performance of the robot leg mechanism and motion behaviors, the kinematic motion analysis was performed in SolidWorks and MATLAB. The leg mechanism used is effective for rough terrain areas because it is capable of walking on the terrain with different amplitudes in terms of surface roughness and aerodynamics.
    Źródło:
    Advances in Science and Technology. Research Journal; 2019, 13, 3; 43-53
    2299-8624
    Pojawia się w:
    Advances in Science and Technology. Research Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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