15 research outputs found

    Coupling dynamics of a geared multibody system supported by Elastohydrodynamic lubricated cylindrical joints

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    A comprehensive computational methodology to study the coupling dynamics of a geared multibody system supported by ElastoHydroDynamic (EHD) lubricated cylindrical joints is proposed throughout this work. The geared multibody system is described by using the Absolute-Coordinate-Based (ACB) method that combines the Natural Coordinate Formulation (NCF) describing rigid bodies and the Absolute Nodal Coordinate Formulation (ANCF) characterizing the flexible bodies. Based on the finite-short bearing approach, the EHD lubrication condition for the cylindrical joints supporting the geared system is considered here. The lubrication forces developed at the cylindrical joints are obtained by solving the Reynolds’ equation via the finite difference method. For the evaluation of the normal contact forces of gear pair along the Line Of Action (LOA), the time-varying mesh stiffness, mesh damping and Static Transmission Error (STE) are utilized. The time-varying mesh stiffness is calculated by using the Chaari’s methodology. The forces of sliding friction along the Off-Line-Of-Action (OLOA) are computed by using the Coulomb friction models with a time-varying coefficient of friction under the EHD lubrication condition of gear teeth. Finally, two numerical examples of application are presented to demonstrate and validate the proposed methodology.National Natural Science Foundations of China under Grant 11290151, 11221202 and 11002022, Beijing Higher Education Young Elite Teacher Project under Grant YETP1201

    Optimum ejector system design for plastic injection moulds

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    International Journal of Computer Applications in Technology94211-218IJCT

    The implementation of adaptive isoplanar tool path generation for the machining of free-form surfaces

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    Machining of steep regions is an important research topic in the machining of free-form surfaces. A new tool path generation algorithm to adaptively machine free-form surfaces has been recently developed. However, similarly to many newly emerged methods, so far it has not been used in industry because no commercial platform is currently available and the user-developed system is not robust enough for industrial applications. To solve this problem, this paper presents a new implementation method by integrating it in a commercial CAD/CAM system (Pro/Engineer). With this strategy, other than conducts detailed computations for parameters, such as scallop heights and forward steps, or designing the non-cutting functions such as engaging and retracting methods, which are routines in every tool path generation process, the implementation utilizes existing tool path generation templates in Pro/E to generate the required tool paths. This makes the tool path generation process easier and the tool paths generated more practicable because the integration is relieved of the time-consuming routine calculation and the entire cutting and non-cutting functions in the commercial system are transparent to users. Based on the API of Pro/E, the new tool path generation method was successfully implemented and cutting tests were conducted. Not losing generality, the implementation could also be conducted in other commercial systems as similar templates are available in these systems as well

    Framework for establishing integrated kidney care programs in low- and middle-income countries

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    Secular increases in the burden of kidney failure is a major challenge for health systems worldwide, especially in low- and middle-income countries (LMICs) due to growing demand for expensive kidney replacement therapies. In LMICs with limited resources, the priority of providing kidney replacement therapies must be weighed against the prevention and treatment of chronic kidney disease, other kidney disorders such as acute kidney injury, and other noncommunicable diseases, as well as other urgent public health needs. Kidney failure is potentially preventable�not just through primary prevention of risk factors for kidney disease such as hypertension and diabetes, but also by timely management of established chronic kidney disease. Among people with established or incipient kidney failure, there are 3 key treatment strategies�conservative care, kidney transplantation, and dialysis�each of which has its own benefits. Joining up preventive care for people with or at risk for milder forms of chronic kidney disease with all 3 therapies for kidney failure (and developing synergistic links between the different treatment options) is termed �integrated kidney care� and has potential benefits for patients, families, and providers. In addition, because integrated kidney care implicitly considers resource use, it should facilitate a more sustainable approach to managing kidney failure than providing one or more of its components separately. There is currently no agreed framework that LMIC governments can use to establish and/or scale up programs to prevent and treat kidney failure or join up these programs to provide integrated kidney care. This review presents a suggested framework for establishing integrated kidney care programs, focusing on the anticipated needs of policy makers in LMICs. © 2020 International Society of Nephrolog
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