scholarly journals Directional presplit blasting in an innovative no-pillar mining approach

2019 ◽  
Vol 16 (5) ◽  
pp. 875-893 ◽  
Author(s):  
Jinzhu Hu ◽  
Xingyu Zhang ◽  
Yubing Gao ◽  
Zimin Ma ◽  
Xinzeng Xu ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Field Test ◽  
Concentration Factor ◽  
New Technology ◽  
Simulation Method ◽  
Explosion Pressure ◽  
Element Simulation ◽  
Pillar Mining ◽  
The Relationship ◽  
Presplit Blasting

Abstract Directional presplit blasting (DPB) technology for an innovative no-pillar mining approach is introduced. First, a mechanical model is established to analyze crack initiation and coalescence using the new technology. The explosion pressure formula containing tress concentration factor explains the relationship between the quantity of explosives and the crack initiation and coalescence. Subsequently, a dynamic finite element simulation method is used to study the stress and damage evolution process of the blasthole wall in ordinary explosion and DPB. The simulation results indicate that the stress concentration factor is approximately 4c10 for the same quantity of explosives. Finally, a field test was conducted in the Fucheng coal mine of China. Based on the field test, the concept of cracking ability is proposed, the relationship between the quantity of explosives and cracking ability is determined, and the quantity of explosives is divided into four stages that are compatible with the roof rock strength. The results can provide some clinical guidance for application of DPB in other projects of the gob-side entry retaining by roof cutting.

Interface Fracture Criterion Based on Molecular Dynamics Simulation

2011 ◽  
Vol 142 ◽  
pp. 184-187
Author(s):  
Zhen Yang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Crack Initiation ◽  
Fracture Criterion ◽  
Simulation Method ◽  
Dynamics Simulation ◽  
Simplified Model ◽  
Interface Fracture ◽  
Coating Materials ◽  
The Relationship

Fracture of coating materials often occurs at or near the interface, while the mechanism and criterion of interface fracture are not clear yet. A molecular dynamics simulation method was introduced to simulate the interface crack initiation, and the relationship between the interface stress and the interface fracture was found. Although a simplified model was applied, the results still showed some intrinsic features that are useful to study the process of interface fracture. At last, an interface fracture criterion was proposed.

Finite Element Simulation for Titanium Alloy Cutting by Bio-Mimetic Wear-Resistant Cutter

2014 ◽  
Vol 926-930 ◽  
pp. 362-365
Author(s):  
Gui Qiang Liang ◽  
Li Gong Cui ◽  
Fang Shao
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Metal Cutting ◽  
Cutting Temperature ◽  
Simulation Method ◽  
Machining Process ◽  
Basic Principles ◽  
Wear Resistant ◽  
Element Simulation ◽  
The Relationship

Bionics research finds that the non-smooth morphology surfaces of some typical animals can reduce the forward resistances in the movement process. We can imitate these characteristics to reduce the machine tool wear during the machining process, which greatly promotes the machining and production procedure. Using the finite element simulation method, the effect of TC4 bio-mimetic wear-resistant cutter on cutting force, cutting temperature and micro-process were researched in-depth. The results verified the effect of bionic wear-resistant tool on the anti-friction process of metal cutting. On the other hand, we discussed the relationship between the effect and parameter of the tool surface non-smooth morphology is not smooth. Also, this paper revealed the basic principles of bionic wear-resisting tool anti-friction, which provides guidance for the selection of non-smooth morphology.

Analysis of magnetic force and dynamic characteristic for non-contact permanent magnet linear drive device

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1337-1345
Author(s):  
Chuan Zhao ◽  
Feng Sun ◽  
Junjie Jin ◽  
Mingwei Bo ◽  
Fangchao Xu ◽  
...  
Keyword(s):  
Finite Element ◽  
Permanent Magnet ◽  
Dynamic Characteristic ◽  
Driving Force ◽  
Magnetic Circuit ◽  
Response Speed ◽  
Computation Method ◽  
Element Analysis ◽  
Element Simulation ◽  
The Relationship

This paper proposes a computation method using the equivalent magnetic circuit to analyze the driving force for the non-contact permanent magnet linear drive system. In this device, the magnetic driving force is related to the rotation angle of driving wheels. The relationship is verified by finite element analysis and measuring experiments. The result of finite element simulation is in good agreement with the model established by the equivalent magnetic circuit. Then experiments of displacement control are carried out to test the dynamic characteristic of this system. The controller of the system adopts the combination control of displacement and angle. The results indicate that the system has good performance in steady-state error and response speed, while the maximum overshoot needs to be reduced.

Exploring the Influences of Service Characteristics on Individuals’Use Intention of Mobile Health Services (Preprint)

2020 ◽  
Author(s):  
Fei Liu ◽  
Pengkun Wu ◽  
Xitong Guo
Keyword(s):  
Personal Information ◽  
New Technology ◽  
Information Service ◽  
Health Care Research ◽  
Privacy Concern ◽  
Service Adoption ◽  
Service Characteristics ◽  
Research Areas ◽  
New Information ◽  
The Relationship

BACKGROUND Service characteristic factors are verified as the determinants for influencing people’s use intention of mHealth. Exploration of the interactions among the service characteristics of users can play an important role in improving service adoption rate. mHealth service appears to be an emerging new technology that presents a new pattern of healthcare service; however, users have concerns that their personal information might be disclosed and used without permission. This concern hinders people’s adoption behavior of mHealth services. OBJECTIVE The objective of this study is to explore how service characteristics (service relevance and service accuracy) interact to influence individuals’ use intention of mHealth services. This study also investigates the moderating roles of innovativeness and privacy concern. METHODS To meet these objectives, six hypotheses thus developed were empirically validated using a survey to test the effects of service characteristics and personal traits on use intention of mHealth. RESULTS We confirm that service relevance and service accuracy positively and directly influence individuals’ use intention of mHealth services. In addition, innovativeness positively affects the relationship between service relevance and use intention. Privacy concern negatively influences the relationship between service relevance and use intention, but positively influences the relationship between service accuracy and use intention. CONCLUSIONS The present study provides new insights into the influencing factors of individuals’ usage behaviour toward mHealth services. Such insight could provide further understanding of how individuals adopt new information service or technologies, which contribute to both information system and health care research areas in a very promising way.

scholarly journals The Contribution of Urban Morphology to the Formation of the Microclimate in Compact Urban Cores: A Study in the City Center of Thessaloniki

Urban Science ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 37
Author(s):  
Georgios-Rafail Kouklis ◽  
Athena Yiannakou
Keyword(s):  
Field Study ◽  
Urban Form ◽  
Simulation Method ◽  
Urban Morphology ◽  
Green Spaces ◽  
City Center ◽  
Outdoor Spaces ◽  
Microclimatic Conditions ◽  
The Relationship ◽  
The City

The purpose of this paper is to investigate the contribution of urban morphology to the formation of microclimatic conditions prevailing within urban outdoor spaces. We studied the compact form of a city and examined, at a detailed, street plan level, elements related to air temperature, urban ventilation, and the individual’s thermal comfort. All elements examined are directly affected by both the urban form and the availability of open and green spaces. The field study took place in a typical compact urban fabric of an old city center, the city center of Thessaloniki, where we investigated the relationship between urban morphology and microclimate. Urban morphology was gauged by examining the detailed street plan, along with the local building patterns. We used a simulation method based on the ENVI-met© software. The findings of the field study highlight the fact that the street layout, the urban canyon, and the open and green spaces in a compact urban form contribute decisively both to the creation of the microclimatic conditions and to the influence of the bioclimatic parameters.

A Research of Shaft Modal Simulation Method Based on the Preloaded Angular Contact Ball Bearing

2013 ◽  
Vol 389 ◽  
pp. 364-370
Author(s):  
Bei Li ◽  
Jian Bin Zhang ◽  
Lu Sha Jiang
Keyword(s):  
Simulation Analysis ◽  
Simulation Method ◽  
Numerical Control ◽  
Angular Contact Ball Bearing ◽  
Tightening Force ◽  
Shaft System ◽  
Element Simulation ◽  
Rolling Element ◽  
Bearing Stiffness ◽  
Main Spindle

In order to analysis modal characteristic of bearing with pre-tightening force on main spindle of numerical control lathe, this paper proposes a model of spindle modality analysis. This model is used to simulate the preloaded bearing shaft system modal, and the simulation results are verified by modal experiment. This paper takes 7005c as the research object to establish the equivalent-spring model based on the Hertz theory considering the pre-tightening force, whose focus is dealing with the contact between bearings rolling element and raceway. Then the model will be used to get the bearing stiffness for finite element simulation analysis. The shafting modal with preloaded bearing test platform is structured to get the shaft system modal parameters, which is compared with and verified the simulation analysis.

Analysis on the Anti-Glare Plate Setting Distance on Horizontal Curve Sections of Expressway

2014 ◽  
Vol 587-589 ◽  
pp. 2156-2159 ◽  
Author(s):  
Tian Xiao ◽  
Ji Shu Sun ◽  
Can Zhang Jin
Keyword(s):  
Traffic Safety ◽  
Calculation Formula ◽  
Horizontal Curve ◽  
Distance Calculation ◽  
Element Simulation ◽  
Curved Section ◽  
Curve Radius ◽  
The Relationship ◽  
Plate Distance ◽  
Glare Effect

Glare is one of the most important factors threating expressway traffic safety an night. The most commonly way to prevent glaring night is to set anti-glare plate. Different from the straight sections of expressway, the relationship between the front light of vehicles and the distance of anti-glare plate on the horizontal curved section has some-what changed. Through a lot of tests and finite element simulation, the relationship between the distance of anti-glare plate, horizontal curve radius and anti-glare effect were analyzed systematically. Distance calculation formula of anti-glare plate in horizontal curve sections was revised in this paper. The anti-glare plate distance requirement under different expressway alignment design indexes and its calculation formula was proposed. The achievement was beneficial to confirm the anti-glare effect and improve traffic safety. It can provide us with a reference and a supplement of the specification.

Finite Element Analysis of the ESTELA M1 Airplane Firewall (Representative Specimen)

2011 ◽  
Author(s):  
V. Ramirez-Elias ◽  
E. Ledesma-Orozco ◽  
H. Hernandez-Moreno
Keyword(s):  
Finite Element ◽  
Federal Aviation Administration ◽  
Element Model ◽  
Maximum Load ◽  
Load Factor ◽  
Representative Specimen ◽  
Maximum Displacement ◽  
Element Analysis ◽  
Element Simulation ◽  
The Relationship

This paper shows the finite element simulation of a representative specimen from the firewall section in the AEROMARMI ESTELA M1 aircraft. This specimen is manufactured in glass and carbon / epoxy laminates. The specimen is subjected to a load which direction and magnitude are determined by a previous dynamic loads study [10], taking into account the maximum load factor allowed by the FAA (Federal Aviation Administration) for utilitarian aircrafts [11]. A representative specimen is manufactured with the same features of the firewall. Meanwhile a fix is built in order to introduce the load directions on the representative specimen. The relationship between load and displacement is plotted for this representative specimen, whence the maximum displacement at the specific load is obtained, afterwards it is compared with the finite element model, which is modified in its laminate thicknesses in order to decrease the deviation error; subsequently this features could be applied to perform the whole firewall analysis in a future model [10].

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