scholarly journals Ground Simulation Test of 2D Dynamic Overload Environment of Fuze Launching

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zhibo Wu ◽  
Tiehua Ma ◽  
Yanbing Zhang ◽  
Hongyan Zhang
Keyword(s):  
Pulse Width ◽  
High Speed ◽  
Centrifugal Acceleration ◽  
Simulation Test ◽  
Loading Method ◽  
Study Results ◽  
High Kinetic Energy ◽  
Micro Electromechanical System ◽  
The Impact ◽  
Peak Value

The fuze launch process is subjected to backseat and spin overloads. To address this issue, a loading method of a 2D dynamic acceleration environment was developed in this study for testing fuze antioverload performance on ground. The techniques of flywheel energy storage, high-speed impact, and centrifugal rotation in the track are combined in a dynamic analysis and simulation. First, the flywheel is rotated at a constant speed by a variable-frequency motor to obtain high kinetic energy. Second, an impact hammer is instantaneously released on the specimen at a high speed, loading the backseat acceleration environment. Finally, the impact hammer is retracted, and the specimen is rotated in the track instead of spinning around its axis, thereby loading the centrifugal acceleration environment. The peak value and pulse width of the 2D overload acceleration can be adjusted by changing the speed of the flywheel and buffers in the abovementioned process. The experimental and simulation results observed that the peak value of backseat acceleration could reach 34,559 g, the pulse width was approximately 400 μs, and the peak value of the centrifugal acceleration was 1,020 g. The study results showed that the proposed approach fulfills the requirements of the 2D overload simulation test of the micro-electromechanical system (MEMS) fuze safety and arming mechanism. The proposed loading method has been successfully applied to ground simulation tests of the MEMS fuze safety and arming mechanism.

Dynamic vacuum pressure tracking control with high-speed on-off valves

2018 ◽  
Vol 232 (10) ◽  
pp. 1325-1336 ◽  
Author(s):  
Gang Yang ◽  
Kai Chen ◽  
Linglong Du ◽  
Jingmin Du ◽  
Baoren Li
Keyword(s):  
Mass Flow ◽  
Pulse Width ◽  
High Speed ◽  
Pulse Width Modulation ◽  
Sliding Mode ◽  
Tracking System ◽  
Vacuum Pressure ◽  
Chamber Pressure ◽  
Asymmetric Structure ◽  
The Impact

A vacuum pressure tracking system with high-speed on-off valves is a discontinuous system due to the discrete nature of high-speed on-off valves. Chamber pressure changes in the system are determined by the mass flow rates during the processes of charging and discharging. Here, a sliding mode controller with an asymmetric compensator based on average mass flow rate is designed for accurate vacuum pressure tracking. The controller output signal is converted into the duty cycles of the high-speed on-off valves via a pulse width modulation pulsing scheme. Owing to the extreme asymmetry of the processes, an asymmetric structure comprising one high-speed on-off valve in the charging unit and three high-speed on-off valves in the discharging unit is applied to weaken the impact of asymmetry. In addition, an asymmetric compensator is also designed to modify the pulse width modulation pulsing scheme to further eliminate the asymmetry. Experimental results indicate that the proposed controller achieves better performance in pressure tracking with the asymmetric compensator overcoming process asymmetry and enhancing system robustness.

scholarly journals Numerical simulation and experimental research of cavitation nozzle based on equation curve

2021 ◽  
Author(s):  
Lifu Wang ◽  
Dongyan Shi ◽  
Zhixun Yang ◽  
Guangliang Li ◽  
Chunlong Ma ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Flow Field ◽  
High Speed ◽  
Quadratic Equation ◽  
Outer Contour ◽  
Study Results ◽  
Fluent Software ◽  
The Impact ◽  
Better Than

Abstract To further investigate and improve the cleaning ability of the cavitation nozzle, this paper proposes a new model that is based on the Helmholtz nozzle and with the quadratic equation curve as the outer contour of the cavitation chamber. First, the numerical simulation of the flow field in the nozzle chamber was conducted using FLUENT software to analyze and compare the impact of the curve parameters and Reynolds number on the cleaning effect. Next, the flow field was captured by a high-speed camera in order to study the cavitation cycle and evolution process. Then, experiments were performed to compare the cleaning effect of the new nozzle with that of the Helmholtz nozzle. The study results demonstrate that effective cavitation does not occur when the diameter of the cavitation chamber is too large. For the new nozzle, with the increase of the Reynolds number, the degree of cavitation in the chamber first increases and then decreases; the cleaning effect is much better than that of a traditional Helmholtz nozzle under the same conditions; the nozzle has the best cleaning effect for the stand-off distance of 300 mm.

scholarly journals The Influence of Origami and Rectangular Crash Box Variations on MPV Bumper with Offset Frontal Test Examination toward Deformability

2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Imam Kusyairi
Keyword(s):  
High Speed ◽  
Oblique Impact ◽  
Isotropic Hardening ◽  
Deformation Pattern ◽  
Frontal Impact ◽  
Simulation Test ◽  
Rectangular Pattern ◽  
Result Show ◽  
Deformation Patterns ◽  
The Impact

Crash Box attached between bumper and chassis of a car serving as a kinetic energy absorber during the collision. In previous research, origami pattern crash box was tested at low speed, high speed, and frontal impact and oblique impact directions. They resulted predictable collapse and stable deformation patterns. It is directly proportional to the energy absorption during the impact. Origami pattern crash box was modeled in square but it cannot be used if it is applied in MPV car, the geometry is unsuitable to the bumper and chassis. Therefore, in this research, the crash box designed according to the size of bumper and chassis of MPV car where its shape is rectangular on the surface. This research will compare the deformation pattern between origami and rectangular crash box adapted to conditions and dimensions of the MPV car. Design built using CAD software and simulation is performed using FEM (Finite Element Method) software. Simulation test modeled with impactor, bumper and crash box, while offset frontal test with 16 km/h impact speed conducted using material bilinear isotropic hardening modeling. Result show that origami pattern crash box has predictable deformation pattern than rectangular pattern crash box.

scholarly journals A Human Centric Approach on the Analysis of the Smart City Concept: the case study of the Limassol city in Cyprus

2018 ◽  
Vol 45 ◽  
pp. 305-320 ◽  
Author(s):  
Maroula N. Alverti ◽  
Kyriakos Themistocleous ◽  
Phaedon C. Kyriakidis ◽  
Diofantos G. Hadjimitsis
Keyword(s):  
Educational Attainment ◽  
High Speed ◽  
Broad Band ◽  
Postal Code ◽  
Data Set ◽  
High Educational Attainment ◽  
Study Results ◽  
The Impact ◽  
The City ◽  
High Educational

Abstract. The impact of medium-sized southern European cities challenges on the “smartness” of the city is a quite interesting case that is not quite analyzed yet. Our scientific objective is to find a simple understandable model linking human smart characteristics to a group of socio-demographic and urban environment indices, applied to the case of Limassol Urban Complex, the southernmost European city, with a total population of 208 980. The data set of the analysis contains 25 variables in 3 thematic domains using as spatial analysis level, the 126 postal code areas of the most urbanized part of the city. The study results obtained through multivariate statistical analysis and thematic cartography using GIS technology. The results reveal that the human smart characteristics consist of the use of high-speed internet and broad band telephony, recycling activities, employment in creative industry, high educational attainment and open-mindedness (i.e. participation in EU elections), are significantly correlated with demographic dynamics and built infrastructure characteristics. Creativity and open-mindedness tend to appear in most densely urban areas, mostly occupied by indigenous inhabitants. Recycling and technology oriented smart characteristics are mostly correlated with no-native residents, and high educational attainment. In the outskirts of the city of Limassol the developing dynamics are almost the same with a greater blend between native and non-native inhabitants.

Numerical Simulation of Impact-Echo Method Identify the Depth of Honeycomb Damage in Unballasted Track

2014 ◽  
Vol 584-586 ◽  
pp. 2060-2067 ◽  
Author(s):  
Chang Sheng Zhou ◽  
Ping Wang ◽  
Zhi Peng Hu ◽  
Hao Zhu
Keyword(s):  
High Speed ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Impact Echo ◽  
Finite Element Software ◽  
Ballastless Track ◽  
The Impact ◽  
Non Destructive ◽  
Impact Echo Method ◽  
Peak Value

Through the honeycomb damage that is appear in unballasted track will affect the safe operation of high-speed train, accurate detection of honeycomb damage is very important. Impact-echo method is a non-destructive testing method. Based on the principle of impact echo, author using the finite element software ANSYS LS-DYNA3D to simulate the impact-echo, testing and verifying the feasibility and accuracy of impact-echo method in discerning unballasted track damage. By analyzing the calculated result of honeycomb damage in slab track and double-block ballastless track, it is shows that: according to back calculate the depth of damage base on the peak value in acceleration spectrum graph, the honeycomb damage in different depth can be accurate located.

scholarly journals Effects of Deep Cryogenic Treatment on the Microstructure and Properties of Rolled Cu Foil

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5498
Author(s):  
Zhichao Dong ◽  
Xiangyu Fei ◽  
Benkui Gong ◽  
Xinyu Zhao ◽  
Jiwei Nie
Keyword(s):  
Mechanical Properties ◽  
Dislocation Density ◽  
High Speed ◽  
Treatment Time ◽  
Cryogenic Treatment ◽  
Wearable Electronics ◽  
Deep Cryogenic Treatment ◽  
Cu Foil ◽  
The Impact ◽  
Peak Value

The development of fifth-generation (5G) communication and wearable electronics generates higher requirements for the mechanical properties of copper foil. Higher mechanical properties and lower resistance are required for flexible copper-clad laminate and high-frequency and high-speed Cu foil. Deep cryogenic treatment (DCT), as a post-treatment method, has many advantages, such as low cost and ease of operation. However, less attention has been paid to the impact of DCT on rolled Cu foil. In this study, the effects of DCT on the microstructure and mechanical properties of rolled Cu foil were investigated. The results show that as the treatment time increased, the tensile strength and hardness first increased and then decreased, reaching a peak value of 394.06 MPa and 1.47 GPa at 12 h. The mechanical property improvement of rolled Cu foil was due to the grain refinement and the increase of dislocation density. The dislocation density of rolled Cu foil after a DCT time of 12 h was determined to have a peak value of 4.3798 × 1015 m−2. The dislocation density increased by 19% and the grain size decreased by 12% after 12 h DCT.

Income Diversification and Bank Efficiency in Vietnam

2017 ◽  
pp. 52-67
Author(s):  
Sang Nguyen Minh
Keyword(s):  
Regression Model ◽  
Commercial Banks ◽  
Banking System ◽  
Operational Efficiency ◽  
Commercial Banking ◽  
Tobit Regression ◽  
Income Diversification ◽  
Positive Effects ◽  
Study Results ◽  
The Impact

This study uses the DEA (Data Envelopment Analysis) method to estimate the technical efficiency index of 34 Vietnamese commercial banks in the period 2007-2015, and then it analyzes the impact of income diversification on the operational efficiency of Vietnamese commercial banks through a censored regression model - the Tobit regression model. Research results indicate that income diversification has positive effects on the operational efficiency of Vietnamese commercial banks in the research period. Based on study results, in this research some recommendations forpolicy are given to enhance the operational efficiency of Vietnam’s commercial banking system.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

Some reflections on social structure: Theoretical and practical aspects

2020 ◽  
Vol 18 (6) ◽  
pp. 1063-1078
Author(s):  
T.N. Skorobogatova ◽  
I.Yu. Marakhovskaya
Keyword(s):  
Service Industry ◽  
External Factors ◽  
Infrastructure Development ◽  
Social Infrastructure ◽  
Social Sphere ◽  
The Social ◽  
Study Results ◽  
The Republic ◽  
Internal And External Factors ◽  
The Impact

Subject. This article discusses the role of social infrastructure in the national economy and analyzes the relationship between the notions of Infrastructure, Service Industry and Non-Productive Sphere. Objectives. The article aims to outline a methodology for development of the social infrastructure of Russia's regions. Methods. For the study, we used the methods of statistical and comparative analyses. The Republic of Crimea and Rostov Oblast's social infrastructure development was considered as a case study. Results. The article finds that the level of social infrastructure is determined by a number of internal and external factors. By analyzing and assessing such factors, it is possible to develop promising areas for the social sphere advancement. Conclusions. Assessment and analysis of internal factors largely determined by the region's characteristics, as well as a comprehensive consideration of the impact of external factors will help ensure the competitiveness of the region's economy.

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