scholarly journals Building an analytical model of the gravitational grain movement in an open screw channel with variable inclination angles

2021 ◽  
Vol 3 (7 (111)) ◽  
pp. 100-112
Author(s):  
Volodymyr Arendarenko ◽  
Anatoliі Antonets ◽  
Oleg Ivanov ◽  
Ihor Dudnikov ◽  
Tetiana Samoylenko
Keyword(s):  
Coordinate System ◽  
Flow Rate ◽  
Theoretical Justification ◽  
Initial Flow ◽  
Screw Channel ◽  
Maximum Value ◽  
R Ratio ◽  
Cylindrical Coordinate ◽  
Grain Flow ◽  
Inclination Angles

Existing technical means for loading silos with grain material do not fully meet the needs of production. The issue related to grain injury remains urgent, which predetermines the need to design a gravitational loader of another principle of operation with the appropriate theoretical justification for the movement of grain material in it. This paper has presented and substantiated the model of the gravitational movement of grain in the peripheral open screw channel with two variable angles of inclination. The model is based on the system of forces in the cylindrical coordinate system, acting on the volume of grain flow in the peripheral screw channel. The grain speed at the end of the braking section of the channel should be as low as possible but not less than the initial flow rate at the beginning of the acceleration section. The model takes into consideration this condition and ensures the optimal passage of grain along any part of the channel. The reported model makes it possible to obtain the speed of grain movement at any time, takes into consideration the height of the bunker hole and the dependence between the angles of inclination of the spirals of acceleration and brake sections. A mathematical dependence is given for these angles that ensures the passage of grain without its discharge and, at the same time, prevents injury to the grain mass due to a controlled decrease in the resulting speed. A separate dependence is provided to find the time at which the grain increases its speed on the acceleration section, reaching the maximum value. Based on the model, a peripheral open screw channel with two angles of inclination of spirals α and β has been proposed. For this channel, the relationships between its key parameters have been established, in particular, values have been substantiated for the recommended angles of 41°…45° for the acceleration section and 39°…35° for the brake section, respectively, as well as the hо/r ratio not less than 0.6...0.7.

Comparison Considerations Toward Investigating the Factors of Load and Age Group on the Maximum Reach Envelope

2020 ◽  
pp. 001872082096501
Author(s):  
Heather Johnston ◽  
Colleen Dewis ◽  
John Kozey
Keyword(s):  
Coordinate System ◽  
Three Dimensional ◽  
Spherical Coordinate System ◽  
Upper Body ◽  
Group Differences ◽  
Anthropometric Measures ◽  
Younger Adults ◽  
Present Measurement ◽  
Spherical Coordinate ◽  
Cylindrical Coordinate

Objective The objectives were to compare cylindrical and spherical coordinate representations of the maximum reach envelope (MRE) and apply these to a comparison of age and load on the MRE. Background The MRE is a useful measurement in the design of workstations and quantifying functional capability of the upper body. As a dynamic measure, there are human factors that impact the size, shape, and boundaries of the MRE. Method Three-dimensional reach measures were recorded using a computerized potentiometric system for anthropometric measures (CPSAM) on two adult groups (aged 18–25 years and 35–70 years). Reach trials were performed holding .0, .5, and 1 kg. Results Three-dimensional Cartesian coordinates were transformed into cylindrical ( r, θ , Z) and spherical ( r, θ, ϕ) coordinates. Median reach distance vectors were calculated for 54 panels within the MRE as created by incremented banding of the respective coordinate systems. Reach distance and reach area were compared between the two groups and the loaded conditions using a spherical coordinate system. Both younger adults and unloaded condition produced greater reach distances and reach areas. Conclusions Where a cylindrical coordinate system may reflect absolute reference for design, a normalized spherical coordinate system may better reflect functional range of motion and better compare individual and group differences. Age and load are both factors that impact the MRE. Application These findings present measurement considerations for use in human reach investigation and design.

Nonlinear Axisymmetric Deformation Model for Structures of Revolution

2011 ◽  
Vol 3 (4) ◽  
pp. 420-447
Author(s):  
Ayman Mourad ◽  
Jawad Zaarour
Keyword(s):  
Coordinate System ◽  
Three Dimensional ◽  
Axisymmetric Deformation ◽  
Large Displacement ◽  
Deformation Model ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Cylindrical Coordinate ◽  
Mathematical Derivation ◽  
Displacement Effects

AbstractAn axisymmetric formulation for modeling three-dimensional deformation of structures of revolution is presented. The axisymmetric deformation model is described using the cylindrical coordinate system. Large displacement effects and material nonlinearities and anisotropy are accommodated by the formulation. Mathematical derivation of the formulation is given, and an example is presented to demonstrate the capabilities and efficiency of the technique compared to the full three-dimensional model.

Evaporation and Viscous Flow in Triangular Grooves in Micro Heat Pipes

2005 ◽  
Author(s):  
Mulugeta Markos ◽  
Vladimir S. Ajaev ◽  
G. M. Homsy
Keyword(s):  
Cross Section ◽  
Flow Rate ◽  
Cross Sections ◽  
Wedge Angle ◽  
Heat Pipes ◽  
Type Model ◽  
Pressure Gradients ◽  
Maximum Value ◽  
Dry Out ◽  
Micro Heat Pipes

We develop a lubrication type model of a liquid flow in a wedge in the limit of small capillary numbers and negligible gravity. The model incorporates the effects of capillary pressure gradients and evaporation. Steady vapor-liquid interface shapes are found for a range of parameters. In the limit of weak evaporation the flow is the same in all cross-sections and can be controlled by changing the wedge angle. We find the wedge angle that results in the maximum value of the flow rate for a given contact angle. For high evaporation rates, both the flow rate and the amount of liquid in each cross-section along the wedge decrease until the point of dry-out is reached. The location of the dry-out point is studied as a function of evaporation. Practical suggestions about optimization of micro heat pipes are given.

Principle and structure of a multi-chamber piezoelectric pump with large flow rate integrated into printed circuit board

2022 ◽  
pp. 1045389X2110721
Author(s):  
Yun-Hao Peng ◽  
Dai-Hua Wang ◽  
Lian-Kai Tang
Keyword(s):  
Flow Rate ◽  
Compression Ratio ◽  
Layer Structure ◽  
Experimental Results ◽  
Processing Technology ◽  
Rate Model ◽  
Piezoelectric Pump ◽  
Central Deflection ◽  
Maximum Value ◽  
Large Flow

Parametric simulation of multi-chamber piezoelectric pump proposed by authors shows that its flow rate is positively correlated with chamber compression ratio when height of chamber wall is not less than central deflection of circular piezoelectric unimorph actuator (CPUA). Therefore, in this paper, principle and structure of multi-chamber piezoelectric pump with novel CPUAs with three-layer structure are proposed and realized, so as to improve its chamber compression ratio, and then improve its flow rate. Its processing technology compatible with PCB processing technology is studied and its flow rate model is established. Central deflection of CPUA with three-layer structure and the flow rate characteristics are tested. Experimental results show that when the central deflection of CPUA with three-layer structure reaches the maximum value of 106.8 μm, the chamber compression ratio and flow rate of multi-chamber piezoelectric pump reach the maximum value of 50% and 3.11 mL/min, respectively. The maximum flow rate is increased by 622% compared to unimproved pump. By comparing experimental results with numerical and finite element simulation results, the realized multi-chamber piezoelectric pump has large flow rate and the established flow rate model can predict its flow rate.

The Cost-Benefit of Pulse-Oximeter Use in the Prehospital Environment

1999 ◽  
Vol 14 (4) ◽  
pp. 41-46 ◽  
Author(s):  
Andrew J. Macnab ◽  
Lark Susak ◽  
Faith A. Gagnon ◽  
Janet Alred ◽  
Charles Sun
Keyword(s):  
Oxygen Saturation ◽  
Pulse Oximetry ◽  
Flow Rate ◽  
Cost Savings ◽  
Cost Benefit ◽  
Standard Protocol ◽  
Clinical Value ◽  
Transport Time ◽  
Initial Flow ◽  
Flow Rates

AbstractIntroduction:Pulse-oximetry has proven clinical value in Emergency Departments and Intensive Care Units. In the prehospital environment, oxygen is given routinely in many situations. It was hypothesized that the use of pulse oximeters in the prehospital setting would provide a measurable cost-benefit by reducing the amount of oxygen used.Methods:This was a prospective study conducted at 12 ambulance stations (average transport times >20 minutes). Standard care protocols and paramedic assessments were used to determine which patients received oxygen and the initial flow rate used. Pulse-oximetry measurements (oxygen-saturation measured by pulse oximetry) were then taken. If oxygen-saturation measured by pulse oximetry fell below 92% or rose above 96% (except in patients with chest pain), oxygen (O2) flow rates were adjusted. Costs of oxygen use were calculated: volume that would have been used based on initial flow rate; and volume actually used based on actual flow rates and transport time.Methods:A total of 1,907 patients were recruited. Oximetry and complete data were obtained on 1,787 (94%). Of these, 1,329 (74%) received O2 by standard protocol: 389 (27.5%) had the O2 flow decreased; 52 had it discontinued. Eighty-seven patients (6%) not requiring O2 standard protocol were hypoxemic (oxygen-saturation measured by pulse oximetry < 92%) by oximetry, and 71 patients (5%) receiving oxygen required flow rate increases. Overall, O2 consumption was reduced by 26% resulting in a cost-savings of $0.20 / patient. Prehospital pulse-oximetry allows unncessary or excessive oxygen therapy to be avoided in up to 55% of patients transported by ambulance and can help to identify suboptimally oxygenated patients (11%).Conclusion:Rationalizing the O2 administration using pulse-oximetry reduced O2 consumption. Other health care savings likely would result from a reduced incidence of suboptimal oxygenation. Oxygen cost-saving justifies oximeter purchase for each ambulance annually where patient volume exceeds 1,750, less frequently for lower call volumes, or in those services where the mean transport time is less than the 23 minute average noted in this study.

Characteristics Analysis of SCWR During Partial Loss of Reactor Coolant Flow Transient

2012 ◽  
Author(s):  
Juan Chen ◽  
Tao Zhou ◽  
Zhousen Hou ◽  
Canhui Sun
Keyword(s):  
Flow Rate ◽  
Transient Analysis ◽  
Coolant Flow ◽  
Partial Loss ◽  
Initial Flow ◽  
Reactor Coolant ◽  
Loss Of Coolant ◽  
Characteristics Analysis ◽  
And Control ◽  
Supercritical Water Cooled Reactor

Partial loss of reactor coolant flow is one of the most important transients for safety analysis of supercritical water-cooled reactor (SCWR). Taking the super LWR concept provided by Japan as research object, transient analysis of partial loss of coolant flow rate is given by coupled neutronics and thermal hydraulics calculation method. The results show that, when 5% partial loss of coolant flow is happening, maximum cladding temperature would increase firstly with the decreasing of fuel channel inlet coolant flow. Then followed with the neutronic feedback and control operation, maximum cladding temperature decreases and finally return to normal. When 50% partial loss of coolant flow is happening, a scram signal will be given to ensure system safety, but the maximum cladding temperature still shows a significant increase early. On this basis, sensitivity analysis is performed considering the influence of core power and main coolant flow. It is found that maximum peaking value increases significantly following the initial flow rate decreasing, but shows a very little increase caused by core power increasing.

scholarly journals SENSIBILIDADE DE GOTEJADORES À OBSTRUÇÃO POR PARTÍCULAS DE AREIA

Irriga ◽  
2018 ◽  
Vol 23 (2) ◽  
pp. 194-203
Author(s):  
Acácio Perboni ◽  
José Antonio Frizzone ◽  
Rubens Duarte Coelho ◽  
Rogério Lavanholi ◽  
Ezequiel Saretta
Keyword(s):  
Turbulent Flow ◽  
Flow Rate ◽  
Flow Regimes ◽  
Solid Particles ◽  
Automated System ◽  
Particle Sizes ◽  
Initial Flow ◽  
Water Flow Velocity ◽  
Sand Particles ◽  
Micro Irrigation

SENSIBILIDADE DE GOTEJADORES À OBSTRUÇÃO POR PARTÍCULAS DE AREIA     ACÁCIO PERBONI1; JOSÉ ANTONIO FRIZZONE2; RUBENS DUARTE COELHO2; ROGÉRIO LAVANHOLI3 E EZEQUIEL SARETTA4   1 Professor, IFMT, Campo Novo do Parecis - MT, [email protected] 2 Professor, Departamento de Engenharia de Biossistemas, ESALQ/USP, Piracicaba - SP, [email protected]; [email protected] 3 Doutorando, Departamento de Engenharia de Biossistemas, ESALQ/USP, Piracicaba - SP, [email protected] 4 Professor, UFSM, Cachoeira do Sul - RS, [email protected]     1 RESUMO   O objetivo deste trabalho foi avaliar a influência do tamanho e concentração de partículas de areia e da velocidade de fluxo da água nas linhas na sensibilidade à obstrução de um modelo de gotejador do tipo cilíndrico, não regulado, com vazão nominal de 2 L h-1. Foram realizados ensaios de obstrução com areia misturada em água destilada, combinando os seguintes fatores: três faixas granulométricas de partículas de areia, três concentrações de areia e três velocidades de fluxo de água no tubo. A vazão de 32 gotejadores foi medida a cada doze minutos por meio de um sistema automatizado. Nos ensaios com faixa granulométrica de 0,105 a 0,25 mm, ocorreu a obstrução nas concentrações de 250 e 500 mg L-1, para os regimes de escoamento de transição e turbulento. Já na faixa granulométrica de 0,25 a 0,5 mm, ocorreu obstrução nas concentrações de 100, 250 e 500 mg L-1, para os regimes de escoamento de transição e turbulento. A obstrução de gotejadores ocorreu de forma aleatória nas oito linhas. Após obstruídos os gotejadores não desobstruíram com o passar do tempo de ensaio.   Palavras-chave: microirrigação, partículas sólidas inertes, granulometria, concentração     PERBONI, A.; FRIZZONE, J. A.; COELHO, R. D.; LAVANHOLI, R.; SARETTA, E. SENSITIVITY OF DRIPPERS TO CLOGGING CAUSED BY SAND PARTICLES     2 ABSTRACT   The purpose of this research was to assess the influence of concentration and size of sand particles, and water flow velocity in laterals on the sensitivity of drippers to clogging. A cylindrical integrated non-pressure compensating dripper of 2 L h-1 nominal flow rate was used. Experiments were undertaken using distilled water and sand particles, according to the following levels: (a) three ranges of particles sizes; (b) three concentrations of particles; and, (c) three flow velocities in the laterals. The flow rate of 32 drippers was measured at every 12 minutes by an automated system. Within the range of particle sizes from 0.105 to 0.25 mm, clogging of emitters was observed under transient and turbulent flow regimes, and under particles concentration of 250 and 500 mg L-1. Within the range of particles sizes from 0.25 to 0.5 mm, clogging was observed for all concentrations under transient and turbulent flow regimes. Clogging of emitters occurred as a random phenomenon. Once clogged, emitters did not recover their initial flow rate.    Keywords: micro irrigation, inert solid particles, particle size, concentration

scholarly journals FIRST PROJECTION OF THE EQUATION OF MOTION IN THE CYLINDRICAL COORDINATE SYSTEM

2016 ◽  
pp. 90-92
Author(s):  
A. G. Obukhov ◽  
R. E. Volkov
Keyword(s):  
Coordinate System ◽  
Stokes Equations ◽  
Equation Of Motion ◽  
Cylindrical Coordinate System ◽  
Navier Stokes ◽  
Gas Flows ◽  
Heat Conducting ◽  
Complex Flows ◽  
Navier Stokes Equations ◽  
Cylindrical Coordinate

It is proved that complex flows of the viscous compressible heat-conducting gas, arising during heating the vertical field, have a pronounced axial symmetry. Therefore, for the numerical solution of the full Navier-Stokes equations for description of such gas flows it are advisable to use a cylindrical coordinate system. This paper describes the transformation of the first projection of the equation of motion of the full Navier-Stokes equations system. The result of the transformation is a record of the first projection of the equation of a continuous medium motion in the cylindrical coordinate system.

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