scholarly journals Design and Experiment of Hydraulic Scouring System of Wide-Width Lotus Root Digging Machine

Agriculture ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1110
Author(s):  
Yan Liu ◽  
Yong Zhou ◽  
Wen Lv ◽  
Haidong Huang ◽  
Guozhong Zhang ◽  
...  
Keyword(s):  
Performance Test ◽  
Nozzle Geometry ◽  
Operating Efficiency ◽  
Nozzle Outlet ◽  
Factors Affecting ◽  
Nozzle Height ◽  
Outlet Pressure ◽  
Lotus Root ◽  
Scouring Depth ◽  
Nozzle Inlet

In response to the problems of small working width and low operating efficiency of existing hydraulic scouring lotus root harvesters, a wide-width hydraulic scouring system was designed based on a wide-width self-propelled lotus root harvester. The main parameters of the key components were determined through theoretical analysis of the water flow energy of the hydraulic scouring system pipelines. An experimental study was also carried out on the main factors affecting the working performance of this hydraulic scouring system. Through hydrodynamic simulation tests, the effect of nozzle type and constriction section structure on the turbulence intensity at the nozzle outlet and the pressure loss per unit mass of fluid between the nozzle inlet and outlet sections were compared and analysed. The test yielded conical-cylindrical nozzle geometry parameters for nozzle inlet diameter of 40 mm, shrinkage angle of 30°, nozzle outlet straight section length of 20 mm, nozzle outlet diameter of 16 mm, the nozzle had better flushing performance. Single-factor tests were carried out with nozzle outlet pressure, scouring angle and nozzle height from the mud surface as influencing factors. Based on the optimum effective scour depth, a three-factor, three-level Box–Behnken central combination design test was completed. The primary and secondary factors affecting the effective scouring depth were obtained in the following order: nozzle height from the mud surface, nozzle outlet pressure, and scouring angle. Finally, the performance test of the hydraulic scouring system was completed. Results showed that when the nozzle outlet pressure of 0.30 MPa, the scouring angle of 60° and the nozzle height from the mud surface of 0 mm, the effective scouring depth was 395 mm, the lotus root floating rate was 90% and the damage rate was 5%, which meet the requirements of lotus root harvesting operations.

scholarly journals Association Between Cognitive Function and Mechanical Pattern of Landing

2021 ◽  
Author(s):  
Nafiseh Mohammadkhani ◽  
Ramin Balouchy ◽  
Mohammadreza Ghasemian
Keyword(s):  
Cognitive Load ◽  
Sustained Attention ◽  
Lower Limb ◽  
Performance Test ◽  
Sports Injuries ◽  
Continuous Performance Test ◽  
Lower Limb Injuries ◽  
Basketball Players ◽  
Factors Affecting ◽  
Limb Injuries

Introduction: In examining the factors affecting sports injuries, the emphasis is always on physical variables, while cognitive and psychological characteristics can also be effective. Hence, the present study aimed to investigate the relationship between sustained attention as  a neurocognitive function and landing error as a mechanical factor associated with lower limb injuries. Materials and Methods: 44 female basketball players aged 18-25 years at the national league level participated in this study. The participants were assessed using the continuous performance test, and their landing-jumping was evaluated by the landing error scoring system in two conditions of high and low cognitive load. Results:  The results showed that people’s  landing errors increased significantly as a result  of increased cognitive needs (P=0.0001). Also, the findings revealed a positive correlation between omission and commission errors with landing error scores in both low and high cognitive load conditions (P<0.05). Conclusion: Sustained attention could predict the landing error score that is considered a  key risk factor of lower limb injuries. It is recommended that multiple cognitive and physical assessments be used to identify athletes at risk of injury. Hence, cognitive enhancement protocols may be effective along with physical preparation programs.

THE EFFECTS OF NOZZLE NUMBER AND OUTLET GEOMETRY ON GRINDING PROCESS WITH MINIMUM QUANTITY COOLING (MQC) BY NANOFLUID

2021 ◽  
pp. 2150058
Author(s):  
HOOMAN ABIYARI ◽  
MOHAMMAD MAHDI ABOOTORABI
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Transfer Functions ◽  
Cutting Temperature ◽  
Nozzle Geometry ◽  
Grinding Process ◽  
Nozzle Outlet ◽  
Outlet Cross Section ◽  
Minimum Quantity ◽  
High Heat Transfer

Machining with minimum quantity lubrication (MQL) or minimum quantity cooling (MQC) as a subset of green machining is a process in which small volume fluid of high lubrication and cooling properties alongside high pressure air is used in the material removal process. The heat generated in the grinding process has a great impact upon the workpiece quality. Serving lubrication and heat transfer functions, cutting fluids have an essential role in reducing the temperature and thus improving the process of grinding. In this research, nanofluid made of graphene nanoparticles in water-based fluid as a cutting fluid of high heat transfer is utilized to investigate the effects of nozzle number and nozzle geometry of the MQC system on the cutting temperature and surface roughness of the workpiece. The effect of geometry and number of nozzles on grinding with MQC has not been studied so far. The study findings show that the nozzle outlet cross-section of rectangular, compared to circular, decreases the surface roughness and temperature by 30% and 36%, respectively. Moreover, compared to the single nozzle, the use of three nozzles results in a decrease of 19% and 31.7% in the surface roughness and temperature. Under the same machining conditions, the MQC method by 0.15[Formula: see text]wt.% nanofluid of graphene in water using a rectangular nozzle outlet of 1.2[Formula: see text]mm width makes surface roughness and temperature reduced by 67.2% and 48.3% compared to the dry condition, whereas decreased by 13.4% and 8.8% compared to the wet method, respectively.

Research on Chinese Codes and Standards of Heat Transfer Performance Testing for Heat Exchangers

2020 ◽  
Author(s):  
Bin Ren ◽  
Xiaoying Tang ◽  
Facai Ren ◽  
Jibing Wang ◽  
Bofeng Bai
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Performance Test ◽  
Heat Transfer Performance ◽  
Performance Testing ◽  
Test Methods ◽  
Transfer Performance ◽  
Factors Affecting ◽  
Nonlinear Fitting ◽  
Test Standards

Abstract Heat exchanger is a device that transfers heat between hot and cold fluids. Due to the different size and type, the actual heat transfer performance is usually not the same as the design value. Meanwhile, various heat exchangers using new types of heat transfer elements have emerged, bringing the difficulty to obtain the heat transfer performance by only theoretical calculation. Therefore, studying test methods and developing test standards for heat exchangers have become the research focus in many countries. In this paper, the basic principles of various performance test methods are firstly introduced, including Wilson plot method, equal Reynolds number method and nonlinear fitting method. Then the restrictions on the use of these methods and the factors affecting the test results are analyzed. Finally, the Chinese codes and standards of performance testing for heat exchangers are listed, including JB/T 10379-2002, GB/T 27698-2011 and TSG R0010-2019. The test methods used in GB/T 27698 are described in detail. The results show that GB 27698 mainly focus on the specification of testing systems and procedures and can test heat transfer performance of almost all types of heat exchangers in industry under different heat transfer modes. However, there are lack of formulas and methods for calculating uncertainty of testing results.

Operating Efficiency Analysis of Energy Industries in Taiwan

2013 ◽  
Vol 869-870 ◽  
pp. 612-620 ◽  
Author(s):  
Nattanin Ueasin ◽  
Anupong Wongchai
Keyword(s):  
Regression Model ◽  
Stock Exchange ◽  
Efficiency Score ◽  
Operating Efficiency ◽  
Data Envelopment ◽  
Tobit Regression ◽  
Factors Affecting ◽  
Taiwan Stock Exchange ◽  
Energy Companies ◽  
Tobit Regression Model

The energy business has played an important role in an economic growth of Taiwan because the market share is in the high value that can make a significant contribution towards regional and local employment. However, Taiwan is lack of energy resources, making the country highly relies on an import for more than 98 percent of its all energy. At present, a top priority of the countrys policy is to develop clean, sustainable, independent, and efficient energy in order to eliminate the vulnerability from external disruption. Therefore, this research aims to assess the operating efficiency and to analyze factors affecting the efficiency scores of the registered energy companies in the Taiwan Stock Exchange (TWSE) recorded during 2003-2012. The super-efficiency data envelopment analysis (SE-DEA) was initially applied to reveal the additional efficiency scores, followed by the Tobit regression model used to analyze what factors determine the efficiency scores. The empirical results showed that seven DMUs performed efficiently, ranking from 7.29 to 1.02. The company with the best operating performance was Taiwan Cogeneration Corporation (TCC), while the Great Taipei Gas Corporation (GTG) revealed the worst efficiency score. Furthermore, the Tobit regression model explained that the higher number of the local employees, the greater the efficiency scores were. Besides, the lower number of the shareholders, the greater the efficiency scores were. As a result, the Taiwans government is supposed to encourage all energy companies to have a higher number of local employees and shareholders to increase their efficiency scores.

Extending “Assessment of Tesla Turbine Performance” Model for Sensitivity-Focused Experimental Design

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Matthew J. Traum ◽  
Fatemeh Hadi ◽  
Muhammad K. Akbar
Keyword(s):  
Reynolds Number ◽  
Power Output ◽  
Performance Model ◽  
Nozzle Geometry ◽  
Design Parameters ◽  
Working Fluid ◽  
Extended Model ◽  
Number Range ◽  
Nozzle Height ◽  
Turbine Performance

The analytical model of Carey is extended and clarified for modeling Tesla turbine performance. The extended model retains differentiability, making it useful for rapid evaluation of engineering design decisions. Several clarifications are provided including a quantitative limitation on the model’s Reynolds number range; a derivation for output shaft torque and power that shows a match to the axial Euler Turbine Equation; eliminating the possibility of tangential disk velocity exceeding inlet working fluid velocity; and introducing a geometric nozzle height parameter. While nozzle geometry is limited to a slot providing identical flow velocity to each channel, variable nozzle height enables this velocity to be controlled by the turbine designer as the flow need not be choked. To illustrate the utility of this improvement, a numerical study of turbine performance with respect to variable nozzle height is provided. Since the extended model is differentiable, power sensitivity to design parameters can be quickly evaluated—a feature important when the main design goal is maximizing measurement sensitivity. The derivatives indicate two important results. First, the derivative of power with respect to Reynolds number for a turbine in the practical design range remains nearly constant over the whole laminar operating range. So, for a given working fluid mass flow rate, Tesla turbine power output is equally sensitive to variation in working fluid physical properties. Second, turbine power sensitivity increases as wetted disk area decreases; there is a design trade-off here between maximizing power output and maximizing power sensitivity.

Technology Research on Waterworks Sludge for Ceramsite

2011 ◽  
Vol 383-390 ◽  
pp. 3352-3355
Author(s):  
Jun He ◽  
Qi Shan Wang
Keyword(s):  
Bulk Density ◽  
Performance Test ◽  
High Strength ◽  
Raw Material ◽  
Technology Research ◽  
Technological Parameters ◽  
Factors Affecting ◽  
Concrete Blocks ◽  
Waterworks Sludge ◽  
Bearing Structure

On the basis of analysis of the component of the sludge from Lingzhuang waterworks and the technological process was studied which use the sludge for raw material to produce the sludge ceramsite. Through a lot of experiments, the several factors affecting the nature of ceramsite were developed and the technological parameters were confirmed. A performance test of the ceramsite shows that when the optimized temperature is 1130°C~1170 °C, the optimized baking time is 5 min, strength of tube pressure of the ceramsite is 8 MPa, bulk density of it is 1200 kg/m3compressive strength of concrete blocks is 40 MPa. So the products could meet the demand on high strength ceremsite. It is gained that the way of waterworks sludge for ceramsite is feasible and can bring certain economical profits, social profits and environmental profits. The products can be used widely to load bearing structure in construction profession.

scholarly journals An Investigation of Pull-Out Force of Semi-Buried Lotus Roots after Hydraulic Scouring

Agriculture ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 706
Author(s):  
Rong Zeng ◽  
Yitao Lin ◽  
Zhihua Wan ◽  
Ming Tu ◽  
Jun Jiao ◽  
...  
Keyword(s):  
Surface Area ◽  
Root Surface ◽  
Root Surface Area ◽  
Burial Depth ◽  
Factors Affecting ◽  
Similar Shape ◽  
Pull Out ◽  
Lotus Root ◽  
Simulation Results ◽  
First Time

Hydraulic scouring is the most effective approach to harvest lotus roots, but its application is largely restricted by the low harvesting rate. After hydraulic scouring, some mature lotus roots are still partially buried in the soil. Therefore, it is highly necessary to develop an appropriate approach to harvest semi-buried lotus roots. In this work, we for the first time studied the interaction between semi-buried lotus roots and soil, as well as analyzing the pull-out process and the factors affecting the pull-out force of semi-buried lotus roots. Firstly, a simple testing platform was designed based on the virtual prototype technology and the tests on pull-out force were conducted on five lotus roots with similar shape but different weights, with the burial depth and pull-out speed as the experimental factors. The results revealed that the maximum pull-out force is not significantly affected by the pull-out speed, whereas it is significantly influenced by the burial depth and the surface area of lotus roots. The maximum pull-out force increased with increasing lotus root surface area and burial depth. In addition, the discrete element method was employed to simulate the pull-out process of lotus root at different pull-out speeds. The simulation results indicated that a higher pull-out speed would result in a greater pull-out force at the same displacement of the lotus root from the soil. Both experimental and simulation results revealed that soil adhesion contributes the most to the pull-out resistance. It was also observed that a slight loosening of semi-buried lotus roots could drastically reduce the pull-out force. These results suggest that some kind of mechanical structure or improvement of water flow can be applied to the existing lotus root harvester to reduce the adhesion between lotus roots and soil. Overall, our findings provide a novel direction for optimizing hydraulic harvesting machines of lotus roots.

Study Investigates Factors Affecting Coefficient of Discharge in Stimulation

2021 ◽  
Vol 73 (06) ◽  
pp. 49-50
Author(s):  
Chris Carpenter
Keyword(s):  
Flow Rate ◽  
Differential Pressure ◽  
Inlet Pressure ◽  
Maximum Pressure ◽  
Hole Size ◽  
Ambient Conditions ◽  
Factors Affecting ◽  
Perforation Hole ◽  
Outlet Pressure ◽  
Coefficient Of Discharge

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 200612, “The Role of Backpressure and Perforation-Hole Erosion on the Magnitude of the Coefficient of Discharge in Hydraulic Fracturing Stimulation,” by Davood M. Yosefnejad, Bernd Fricke, and Joern Loehken, DynaEnergetics Europe, et al., prepared for the 2020 SPE Virtual Europec Conference, 1–3 December. The paper has not been peer reviewed. One of the important factors affecting the near-wellbore-fluid pressure drop is the coefficient of discharge (Cd). In the complete paper, the authors investigate some of the factors that can affect Cd, such as the erosion of the perforated hole and the backpressure given by the fracture. The paper studies the effect of perforation hole size, geometry, and shape on the Cd value at ambient conditions and with backpressure, before and after sand erosion. Setup Specifications and Materials For this study, a high-pressure, high-flow setup was built for Cd measurements, as well as a second setup in which the holes can be eroded by proppant-laden slurries. The test cell was the same for both setups. The holders of the plates were stainless steel and connected to 7-in. pipes approximately 4 ft long on each side. In all the experiments, the flow rate and inlet and outlet pressure data were recorded simultaneously vs. injection time by high-precision sensors. All experiments were carried out at an ambient temperature of 15–28°C. For these flow-test experiments, only water was used, circulated with different pressure differentials to determine the effect of pressure on Cd magnitude. In addition, backpressure was applied through the needle valve to simulate real reservoir conditions and to compare the Cd value with the tests under ambient conditions. The flow rate range of the pump was 1–7 bbl/min at maximum pressures of approximately 2,000 psi. Erosion tests have been performed for 30 minutes with a near-constant flow rate (approximately 1 bbl/min), constant pressure (approximately 200 psi), and constant sand concentration. For the erosion test, a viscosity of approximately 10 cp was used. The sand concentration was kept at 1 to 2 lbm/gal to keep the erosion rate low, which would allow distinguishing between shape-driven changes in Cd and changes caused by an increase of the hole size. The study used machined holes and holes created by differently shaped charges, which also differed in size and geometry. A description of these holes, and associated shaped-charge tests, is provided in the complete paper. Experimental Results and Discussion Generic Holes. In the first sets of experiments, generic holes with different entrance-hole diameters were used. The experiment began with the lowest inlet pressure, which gradually was increased to the maximum pressure. The outlet pressure was kept constant at an ambient pressure. The flow rate increased because of the increase in differential pressure. After reaching the maximum pressure, the inlet pressure was kept constant and the choke on the outlet side was closed step by step to establish a backpressure, which led to a decrease in differential pressure. Surprisingly, the flow rate stayed constant until the differential pressure surpassed 700 psi.

scholarly journals Measuring the Meta Efficiency and Its Determinants on Efficiency in the Korean Coffee Shop Franchise

2020 ◽  
Vol 12 (6) ◽  
pp. 2398
Author(s):  
Doo-Young Park ◽  
Kanghwa Choi ◽  
Dae-Han Kang
Keyword(s):  
Sustainable Growth ◽  
Operating Efficiency ◽  
Data Envelopment ◽  
Truncated Regression ◽  
Coffee Shop ◽  
Factors Affecting ◽  
Strategic Initiatives ◽  
Measurement And Analysis ◽  
Analysis Models ◽  
Small Chain

Previous applications of DEA (data envelopment analysis) models in the field of franchising have been scarce. In particular, measurement and analysis of the operational efficiency of coffee shop franchisors in the explosively growing coffee market in Korea is required. In this study, we categorize 29 Korean coffee shop franchisors into three groups according to their number of franchisees and employ the metafrontier analysis to measure the efficiency of coffee shop franchisors from 2015 to 2018. Based on the results of metafrontier DEA, this study identifies sources of inefficiency within individual coffee shop franchisors to provide insights for coffee franchise operators and investigates efficiency differences between small-chain and medium-chain coffee shop franchisors. Furthermore, the results of bootstrapped truncated regression provide that the external environmental factors affecting the efficiency of each individual group are totally different patterns depending on the franchise group. Based on the analysis results, this study suggests strategic initiatives tailored to individual coffee shop groups to enhance their operating efficiency and identifies the principal operational drivers of the environmental variables to achieve sustainable growth.

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