A Unified CFD Based Approach to a Variety of Condensation Processes in a Viscous Turbulent Wet Steam Flow

A family of quasi linear mathematical models is presented and calculations made for viscous turbulent wet steam flow with a variety of condensation phenomena. These models can be applied to the analysis of equilibrium condensation, homogeneous (spontaneous) condensation, heterogeneous condensation on extraneous particles, and condensation of charged dispersed phase moving in an electrostatic field. The unified model is represented by coupled systems of gas dynamic equations for viscous turbulent two-phase flow, kinetic and electro-kinetic equations tracing out combined processes of size and charge growth, and electromagnetic field equations described an electric field with an account of self- induced in-part by a moving electrical cluster. The numerical procedure is time marching, monotone, implicit, of second order accuracy by space and time coordinates, and exhibits high resolution shock capturing ability. Viscous flow field calculations made with this procedure reveal significant influence on condensation by the shear boundary layers and wakes. Distributions of cooling rate, droplet radius and parameters of the bulk flow are predicted. Verification of the codes against known experimental data is presented

Tingkat Partisipasi Anggota pada Koperasi Unit Desa (Kud) Kusuma Bakti Desa Sialang Kubang Kecamatan Perhentian Raja Kabupaten Kampar

This study aims to; (1) to analyze the level of participation of members of the Koperasi Unit Desa (KUD) Kusuma Bakti; (2) Knowing the obstacles encountered in increasing the participation of members of the board. Research conducted at Koperasi Unit Desa (KUD) Kusuma Bakti the Village Sialang Kubang Subdistrict Perhentian Raja Kampar Regency. The study conducted by using method of survey, the method of sampling was done by Simple Random Sampling, and the samples taken 33 people of the total population. The collecting data of this research was using primay data and secondary data. To analyzed the degree and the problem at participation of this research was using descriptive method. To obtain the degree of participation of members in contributing or mobilize its resources, member participation in decision making, and participation of members in enjoying benefits. Data were analyzed with the participation level Likert's Summated Rating Scale. The study concluded that the overall level of participation of members of KUD Kusuma Bakti get a total score of 2.25 (1.67 to 2.33 are included in the category of medium participation rates). In another side, the programs KUD Kusuma Bakti had some problem that related by the degree of participant were passive in cooperative activities, attendance gave ideas on meeting, and participant in activity and evaluation of programs village cooperatives Kusuma Bakti

Variational Approach of Constructing Reduced Fluid-Structure Interaction Models in Bifurcated Networks

Reduced fluid-structure interaction models have received a considerable attention in recent years being the key component of hemodynamic modeling. A variety of models applying to specific physiological components such as arterial, venous and cerebrospinal fluid (CSF) circulatory systems have been developed based on different approaches. The purpose of this paper is to apply the general approach based on Hamilton’s variational principle to create a model for a viscous Newtonian fluid - structure interaction (FSI) in a compliant bifurcated network. This approach provides the background for a correct formulation of reduced FSI models with an account for arbitrary nonlinear visco-elastic properties of compliant boundaries. The correct boundary conditions are specified at junctions, including matching points in a combined 3D/1D approach. The hyperbolic properties of derived mathematical model are analyzed and used, constructing the monotone finite volume numerical scheme, second-order accuracy in time and space. The computational algorithm is validated by comparison of numerical solutions with the exact manufactured solutions for an isolated compliant segment and a bifurcated structure. The accuracy of applied TVD (total variation diminishing) and Lax-Wendroff methods are analyzed by comparison of numerical results to the available analytical smooth and discontinuous solutions

Application of Variational Principle to Form Reduced Fluid-Structure Interaction Models in Bifurcated Networks

Reduced fluid-structure interaction models have received a considerable attention in recent years being the key component of hemodynamic modeling. A variety of models applying to specific physiological components such as arterial, venous and cerebrospinal fluid (CSF) circulatory systems have been developed based on different approaches. The purpose of this paper is to apply the general approach based on Hamilton’s variational principle to create a model for a viscous Newtonian Fluid - Structure Interaction (FSI) in a compliant bifurcated network. This approach provides the background for a correct formulation of reduced FSI models with an account for arbitrary nonlinear visco-elastic properties of compliant boundaries. The correct boundary conditions are specified at junctions, including the interface between 3D and 1D models. The hyperbolic properties of the derived mathematical model are analyzed and used, constructing a monotone finite volume numerical scheme, second-order accuracy in time and space. The computational algorithm is validated by comparison of numerical solutions with the exact manufactured solutions for an isolated compliant segment and a bifurcated structure. The accuracy of applied total variation diminishing (TVD) and Lax-Wendroff schemes are analyzed by comparison of numerical results to the available analytical smooth and discontinuous solutions, demonstrating a superior performance from the TVD algorithm

Quantification of Hemodynamic Pulse Wave Velocity Based on a Thick Wall Multi-Layer Model for Blood Vessels

Pulse wave velocity (PWV) is an important index of arterial hemodynamics, which lays the foundation for continuous, noninvasive blood pressure automated monitoring. The goal of this paper is to examine the accuracy of PWV prediction based on a traditional homogeneous structural model for thin-walled arterial segments. In reality arteries are described as composite heterogeneous hyperelastic structures, where the thickness dimension cannot be considered small compared to the cross section size. In this paper we present a hemodynamic fluid - structure interaction model accounting for the variation of geometry and material properties in a radial direction. The model is suitable to account for the highly nonlinear orthotropic material undergoing finite deformation for each layer. Numerical analysis of single and two layer arterial segments shows that a single thick layer model provides sufficient accuracy to predict PWV. The dependence of PWV on pressure for three vessels of different thicknesses is compared against a traditional thin wall model of a membrane shell interacting with an incompressible fluid. The presented thick wall model provides greater accuracy in the prediction of PWV, and will be important for blood pressure estimation based on PWV measurements

Functional electrical stimulation for foot drop in multiple sclerosis: a systematic review and meta-analysis of the effect on gait speed

Objective: To review the efficacy of functional electrical stimulation (FES) used for foot drop in people with multiple sclerosis (pwMS) on gait speed in short and long walking performance tests. Data sources: Five databases (Cochrane Library, CINAHL, Embase, MEDLINE, Pubmed) and reference lists were searched. Study selection: Studies of both observational and experimental design where gait speed data in pwMS could be extracted were included. Data extraction: Data were independently extracted and recorded. Methodological quality was assessed using the Effective Public Health Practice Project (EPHPP) tool. Data synthesis: Nineteen studies (described in 20 articles) recruiting 490 pwMS were identified and rated moderate or weak, with none gaining a strong rating. All studies rated weak for blinding. Initial and ongoing orthotic and therapeutic effects were assessed with regards to the impact of FES on gait speed in short and long walking tests. Meta-analyses of the short walk tests revealed a significant initial orthotic effect (t = 2.14, p = 0.016) with a mean increase in gait speed of 0.05 meters per second (m/s) and ongoing orthotic effect (t = 2.81, p = 0.003) with a mean increase of 0.08m/s. There were no initial or ongoing effect on gait speed in long walk tests and no therapeutic effect on gait speed in either short or long walk tests. Conclusions: FES used for foot drop has a positive initial and ongoing effect on gait speed in short walking tests. Further fully-powered randomized controlled trials comparing FES with alternative treatments are required