scholarly journals Research on Impact Performance of Hydraulic Rock Drill with Floating Characteristics of Double Damping System

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Yelin Li ◽  
Zeng Bin ◽  
Yi Tu
Keyword(s):  
Experimental Data ◽  
Impact Energy ◽  
Influence Factors ◽  
Characteristic Parameters ◽  
Impact Performance ◽  
Experimental Scheme ◽  
Rock Drill ◽  
Feed Force ◽  
The Impact ◽  
The Relationship

As a technological innovation of high-power hydraulic rock drill, double damping system has a very important effect on impact performance. The double damping system is a floating mechanism. The characteristics of the floating mechanism have an important influence on the impact energy, frequency, and power of the hydraulic rock drill. Based on orifice throttling theory, the static equilibrium position of a damping piston was calculated, and the characteristic parameters of the double damping system were summarized as damping flow (Qd) and feed force (Fd). According to the characterization parameters of the double damping system, an experimental scheme of the floating characteristics of the double damping system was designed, and the combined experimental data of Qd and Fd were obtained. The 40 groups of experimental data were extracted, and the relationship between the combination (Qd, Fd) and impact energy and frequency and power were analyzed. The combination (Qd, Fd) with maximum and minimum power was selected to analyze the motion law of an impact piston. The maximum drilling power was obtained at the combination (Qd = 8 L·min−1, Fd = 16.25 kN). The influence factors of the double damping system on impact performance were summarized, and the characteristics of the double damping system under optimal impact performance were obtained.

scholarly journals Research on the Matching of Impact Performance and Collision Coefficient of Hydraulic Rock Drill

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Yelin Li
Keyword(s):  
Stress Wave ◽  
Wave Model ◽  
Wave Theory ◽  
Collision Velocity ◽  
Impact Performance ◽  
Impact Stress ◽  
Material Condition ◽  
Rock Drill ◽  
The Impact ◽  
The Relationship

The stress wave produced by the piston impact, on the drill rod, is an important factor affecting impact performance. It is particularly important to control the stress waveform generated by the piston impact on the drill rod to meet the requirements of efficiency and component durability of some impact mechanical systems. Based on wave theory, the impact stress wave model of rock drilling is established, a dimensionless collision coefficient γ is put forward, and the matching relationship between different collision coefficients γ and stress waveforms is analysed. The length of the impact piston under the same material condition determines the change rule of the waveform. The stress waveform experimental verification is thus designed. The pressure chamber curves of different pistons in the rock drill were tested, the collision velocity of the piston was obtained, and the impact energy and impact power were calculated. The relationship between the impact performance and the collision coefficient γ is analysed. When γ is in the range of 9–11, the impact piston’s design of a high-power rock drill can be satisfied. When γ is in the range of 3∼5, it is mainly designed for low-power rock drills.

The Impact of Rural Finance on Rural Economic Development from the Perspective of Efficiency of Discrete Differential Algorithm

2021 ◽  
Vol 7 (5) ◽  
pp. 4358-4365
Author(s):  
Mingxu Peng ◽  
Jiawen Huang
Keyword(s):  
Economic Growth ◽  
Rural Economy ◽  
Choice Model ◽  
Influence Factors ◽  
Maximum Flow ◽  
Pso Algorithm ◽  
Significant Degree ◽  
Theoretical Research ◽  
The Impact ◽  
The Relationship

Objectives: Finance is the core of the national economy. The development of modern rural economy is inseparable from financial support. The relationship between finance and economic growth has always been one of the hot topics in theoretical research and empirical analysis. Methods: Under the background of the development of Internet e-commerce, the maximum flow algorithm was based on the empirical research on the relationship between China’s financial development and economic growth. Results: Based on this, the two-element discrete choice model of Probit and Logistic for economic growth was constructed. Discrete particle swarm optimization (PSO) algorithm was used to estimate the parameters of the model. The significant degree of the influence factors was calculated. Conclusion: Finally, it was calculated that concurrent business was the decisive factor of economic growth.

The effect of microwave pretreatment on impact crushing of lead-zinc ore

2021 ◽  
Vol 118 (5) ◽  
pp. 501
Author(s):  
Yulong Liu ◽  
Dexin Ding ◽  
Wenguang Chen ◽  
Nan Hu ◽  
Lingling Wu ◽  
...  
Keyword(s):  
Energy Input ◽  
Impact Test ◽  
Characteristic Parameters ◽  
Microwave Pretreatment ◽  
Drop Weight ◽  
Lead Zinc ◽  
Weight Impact ◽  
Impact Crushing ◽  
The Impact ◽  
The Relationship

The relationship between energy input and particle size of ore samples after crushing and effect of microwave pretreatment on impact crushing of lead-zinc ore were studied by drop weight impact test. The results showed that the lead-zinc ore became softer and had higher degree of crushing after microwave pretreatment. Compared with continuous microwave pretreatment, pulsed microwave pretreatment could improve the drop weight impact crushing efficiency of lead-zinc ore. When the specific comminution energy were 5 kW h/t, 10 kW h/t respectively, the crushing characteristic parameters t10 were 60.42% and 67.46% respectively by continuous microwave. But the values of t10 were increased to 68.64% and 75.88% respectively after pulsed microwave radiation under same microwave power and time. In addition, water quenching could more promote the impact crushing efficiency of lead-zinc ore after microwave irradiation.

Experimental and Numerical Investigation of Dynamic Impact on Universal Breakaway Steel Post

2019 ◽  
Author(s):  
Javad Mehrmashhadi ◽  
Mojdeh A. Pajouh ◽  
John D. Reid
Keyword(s):  
Experimental Data ◽  
Numerical Modeling ◽  
Numerical Model ◽  
Dynamic Impact ◽  
Roadside Safety ◽  
Impact Performance ◽  
Component Testing ◽  
Long Span ◽  
Finite Element Package ◽  
The Impact

Abstract A closed guardrail system, known as “bullnose” guardrail system, was previously developed to prevent out-of-control vehicles from falling into the elephant trap. The bullnose guardrail system originally used Controlled Release Terminal (CRT) wood posts to aid in the energy absorption of the system. However, the use of CRT had several drawbacks such as grading and the need for regular inspections. Universal Breakaway Steel Post (UBSP) was then developed by the researchers at Midwest Roadside Safety Facility as a surrogate for CRT. In this study, the impact performance of UBSP on the weak-axis and strong-axis was studied through numerical modeling and component testing (bogie testing). A numerical model was developed using an advanced finite element package LS-DYNA to simulate the impact on UBSP. The numerical results were compared to experimental data. Further research on soil models was recommended. The numerical model will be used to investigate other applications for UBSP such as the Midwest Guardrail System (MGS) long span system, guardrail end terminal designs, or crash cushions.

scholarly journals Experimental Study on the Energy-Release Characteristics of Fine-Grained Fe/Al Energetic Jets under Impact Loading

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3317
Author(s):  
Li ◽  
Du
Keyword(s):  
Experimental Data ◽  
Energy Release ◽  
Impact Energy ◽  
Impact Loading ◽  
Energetic Materials ◽  
Chemical Properties ◽  
Microscopic Analysis ◽  
Specific Content ◽  
Fine Grained ◽  
The Impact

The energy released by the active metal phase in fine-grained Fe/Al energetic materials enables the replacement of conventional materials in new types of weapons. This paper describes an experiment designed to study the energy-release characteristics of fine-grained Fe/Al energetic jets under impact loading. By means of dynamic mechanical properties analysis, the physical and chemical properties of Fe/Al energetic materials with specific content are studied, and the preparation process is determined. The energy-release properties of fine-grained Fe/Al jets subject to different impact conditions are studied based on experimental data, and energy-release differences are discussed. The results show that for fine-grained Fe/Al energetic materials to remain active and exhibit high strength, the highest sintering temperature is 550 °C. With increasing impact energy, the energy release of fine-grained Fe/Al energetic jets increases. At an impact-energy threshold of 121.1 J/mm2, the chemical reaction of the fine-grained Fe/Al energetic jets is saturated. The experimental data and microscopic analysis show that when the impact energy reaches the threshold, the energy efficiency ratio of Fe/Al energetic jets can reach 95.3%.

THE EXPERIMENTAL INVESTIGATION OF THE PROFIT DISTRIBUTION IN INDUSTRIAL SUPPLY CHAINS WITH AN OUTSIDE OPTION / PELNO PASKIRSTYMO PRAMONINĖSE TIEKIMO GRANDINĖSE EKSPERIMENTINIS TYRIMAS

2010 ◽  
Vol 16 (3) ◽  
pp. 487-501 ◽  
Author(s):  
Harald David Stein ◽  
Romualdas Ginevičius
Keyword(s):  
Experimental Data ◽  
Outside Option ◽  
Profit Distribution ◽  
Cooperative Relationships ◽  
Distribution Rule ◽  
Internet Experiments ◽  
Theoretical Predictions ◽  
Cooperation Partners ◽  
The Impact ◽  
The Relationship

There is an industrial supply chain, where an individual customer selects a supplier and excludes other ones. If the excluded supplier has the possibility to overtake the relationship afterwards, he has big influence on the relationship among the cooperation partners. A profit distribution rule has been developed that considers the impact of the excluded supplier. The paper presents round based games in which the present values change and influence the cooperative relationships. First, examples with ideal‐typical numbers are calculated and depicted by the software “MATLAB”. Internet experiments are made with participants on the basis of the software “z‐tree” in order prove the relevance of the proposed profit distribution rule. Finally, the experimental data is compared with the theoretical predictions. Santrauka Paprastai pramoninio tiekimo grandineje klientas pasirenka konkretų tiekėja ir atmeta kitus. Jei veliau su atmestuoju tiekėju vis dėlto užmezgami santykiai, klientas įgyja didelę svarbą pletojant partnerių santykius. Sukurta pelno paskirstymo taisyklė, įvertinanti atmesto tiekejo įtaka. Straipsnyje pateikiama serija žaidimų, kuriuose kinta esama vertė ir daroma įtaka partnerių santykiams. Pirma, naudojantis MATLAB programinė įranga apskaičiuojamos ir atvaizduojamos būdingosios reikšmės. Antra, pasitelkus Z‐tree programinę įranga atliktas internetinis eksperimentas siekiant įrodyti, kad pasiūlyta pelno paskirstymo taisyklė galioja. Galiausiai eksperimentiniai duomenys palyginami su teorinėmis prognozėmis.

scholarly journals Negative self-appraisal mediates the relationship between mindfulness and confidence among adolescent female provincial hockey players in South Africa

10.17159/4371 ◽  
2019 ◽  
Vol 31 (1) ◽  
pp. 1-5
Author(s):  
Stephen Walker
Keyword(s):  
Indirect Effect ◽  
Correlation Coefficients ◽  
Ordinary Least Squares ◽  
Mental Toughness ◽  
Adolescent Female ◽  
Least Squares Regression ◽  
Impact Performance ◽  
Hockey Players ◽  
The Impact ◽  
The Relationship

Introduction: Mounting evidence suggests that mindfulness is positively related to athletic performance and athlete wellbeing. However, few attempts have been made to uncover the psychological processes by which mindfulness might impact performance. Objective: To determine whether negative self-appraisal mediates the relationship between mindfulness and the confidence component of mental toughness among provincial adolescent female hockey players. Methods: Provincial adolescent female hockey players (N=486) completed measures of mindfulness, mental toughness-related confidence and negative self-appraisal. Correlation coefficients were calculated between all variables included in the study. An ordinary least-squares regression analysis was performed to test the indirect effect of negative self-appraisal on the relationship between mindfulness and confidence. Results: Negative self-appraisal exhibited an indirect effect on the relationship between mindfulness and the confidence component of mental toughness (b = .06, SE = .0, CI95 = .04, .09). A subsequent Soble test confirmed that negative self-appraisal served as a statistically significant mediator (b = .06, SE = .01, Z = 5.76, p = .001) in the model. Furthermore 78.3% of the variance in the effect of mindfulness on the confidence component of mental toughness was accounted for by negative self-appraisal. Conclusion: The effect of mindfulness on the confidence component of mental toughness among adolescent athletes is mediated by negative self-appraisal. Based on the current findings, mindfulness seems to foster confidence by lessening the impact of rigid negative appraisals of one’s performance and worth as an athlete. Keywords: mindfulness, confidence, negative self-appraisal, mediation, adolescent female athlete

Simulation and Experimental Study on the Impact of Breadth of Back Blade on Axial Force Balance

2011 ◽  
Vol 130-134 ◽  
pp. 1568-1572
Author(s):  
Hui Wang ◽  
Jie Gang Mu ◽  
Miao Yin Su ◽  
Shui Hua Zheng ◽  
Jin Jing Zhao ◽  
...  
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Experimental Study ◽  
Axial Force ◽  
Three Dimensional ◽  
Force Balance ◽  
Simulation And Experiment ◽  
Simulation Results ◽  
The Impact ◽  
The Relationship

The paper studies the relationship between axial force and breadth of back blade by numerical simulation and experiment. On the basis of the RNG k-ε turbulence model and technology of compact local grids and regional computing, three dimensional numerical simulations to 100HZ165-250 centrifugal pump with various breadths were carried out. Through comparing and analyzing of the flow field, it can be seen that the axial force reduces with the increase of the back blade breadth. After that, the simulation results were verified by the experimental data got from different test devices, and it shows that the conclusions are reliable.

A Method for Assessing the Overall Impact Performance of Riot Helmets

2003 ◽  
Vol 19 (3) ◽  
pp. 246-254 ◽  
Author(s):  
Jean-Philippe Dionne ◽  
Ismail El Maach ◽  
Ahmed Shalabi ◽  
Aris Makris
Keyword(s):  
Comparative Study ◽  
Impact Energy ◽  
Energy Levels ◽  
Performance Impact ◽  
Impact Performance ◽  
Frontal Impacts ◽  
National Institute Of Justice ◽  
Crowd Control ◽  
The Face ◽  
The Impact

The objective of the present paper is to investigate the overall impact performance of various riot helmets in a comparative study. The National Institute of Justice (NIJ-0104.02) and the Canadian Standards Association (CSA-Z611-02) standards regulate the use of riot helmets in North America. Both sets of standards have a number of requirements for impact performance. Impact tests carried out with the use of a drop tower apparatus compliant with NIJ test protocols demonstrated large differences in impact attenuation level among the helmets from six manufacturers in terms of frontal and lateral impacts to the shell, and face-shield deflection. For instance, the impact energy yielding a head form acceleration of 300 g’s was measured for each helmet for frontal impacts on the helmet shell. Values ranging from 69 J up to 171 J were obtained. The energy levels of typical crowd-control threats, e.g., baton blows and projectiles, were quantified and compared with the impact energy values used in the standards. It is observed that the NIJ face-shield deflection requirement is low as compared to actual riot threats, whereas the CSA requirements are more in line with these threats. A novel method was devised to objectively assign a global impact performance score to each helmet. This method takes into account the frontal and lateral impacts to the shell as well as the face-shield deflection tests. It is based on the directional origin of the threat and the geometry of the helmets (frontal percentage area of the visor). From these global performance scores, it is possible to obtain a ranking of the various riot helmets used in the present comparative study. Based on the analysis of the global scores, it was found that appropriate protection of the face (through an impact resistant visor) is the key feature for a helmet that will be used in riot environments.

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