Retrial Queue M/G/1 with Impatient Calls Under Heavy Load Condition

2017 ◽  
pp. 347-357 ◽  
Author(s):  
Ekaterina Fedorova ◽  
Konstantin Voytikov
Keyword(s):  
Retrial Queue ◽  
Load Condition ◽  
Heavy Load

scholarly journals Asymptotic Analysis of the MMРР|M|1 Retrial Queue with Negative Calls under the Heavy Load Condition

2020 ◽  
Vol 20 (4) ◽  
pp. 534-547
Author(s):  
Ekaterina A. Fedorova ◽  
◽  
Anatoly A. Nazarov ◽  
Mais P. Farkhadov ◽  
◽  
...  
Keyword(s):  
Asymptotic Analysis ◽  
Retrial Queue ◽  
Load Condition ◽  
System Capacity ◽  
Stationary Mode ◽  
Single Server ◽  
Numerical Comparison ◽  
Heavy Load ◽  
Retrial Queueing System ◽  
Asymptotic Characteristic

In the paper, a single-server retrial queueing system with MMPP arrivals and an exponential law of the service time is studied. Unserviced calls go to an orbit and stay there during random time distributed exponentially, they access to the server according to a random multiple access protocol. In the system, a Poisson process of negative calls arrives, which delete servicing positive calls. The method of the asymptotic analysis under the heavy load condition for the system studying is proposed. It is proved that the asymptotic characteristic function of a number of calls on the orbit has the gamma distribution with the obtained parameters. The value of the system capacity is obtained, so, the condition of the system stationary mode is found. The results of a numerical comparison of the asymptotic distribution and the distribution obtained by simulation are presented. Conclusions about the method applicability area are made.

scholarly journals Dynamic Modelling and Analysis of the Microsegment Gear

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Yangshou Xiong ◽  
Kang Huang ◽  
Tao Wang ◽  
Qi Chen ◽  
Rui Xu
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Dynamic Modelling ◽  
Weight Ratio ◽  
Load Condition ◽  
Main Idea ◽  
Heavy Load ◽  
Rotating Speed ◽  
Involute Gear

The development of technology requires higher load capacity, rotating speed, power-weight ratio, lower vibration, and noise with respect to the gear transmission. The new type microsegment gear’s tooth profile curve is composed of many microsegments. Previous researches indicate that the microsegment gear has a good static performance, while the dynamic behavior of the microsegment gear has never been investigated. This paper will focus on the dynamic performance of the gear. The profile deviation between microsegment gear and involute gear is regarded as a displacement excitation in the proposed dynamic model. The numerical analysis for three cases is conducted and the results shows that, in low-speed and heavy-load, medium-speed and medium-load conditions, microsegment gear and involute gear both exhibit a good performance, while, in high-speed and heavy-load condition, microsegment gear has a better performance than that of involute gear. The influence of backlash on the dynamic performance is also studied. It is found that the variation of backlash does not change the type of motion, but the vibration amplitude and the stability of the motion are much affected. The main idea in this paper is supposed to provide a novel method for the precision grinding of the microsegment gear.

Study on Dynamic Characteristic of 64m Railway Steel Truss Bridge on Expanding Heavy-Load Transport Condition

2011 ◽  
Vol 90-93 ◽  
pp. 1100-1105
Author(s):  
Zhi Jie Sun ◽  
Jun Min Shen ◽  
Jian Bin Zhao ◽  
Zhong Ming Su
Keyword(s):  
Dynamic Performance ◽  
Load Condition ◽  
Vertical Acceleration ◽  
Performance Parameters ◽  
Heavy Load ◽  
Double Line ◽  
Truss Bridges ◽  
Conventional Condition ◽  
Steel Truss ◽  
Steel Truss Bridges

Through theoretical calculation, systemic analysis of dynamic performance of the 64m single and double line railway steel truss bridges on the expanding condition and conventional condition. Contrast and analysis the main dynamic performance parameters of bridges on the two kinds of operating condition. In 64m steel truss bridges of Shuozhou-Huanghuagang Railway application practice proves that on expanding heavy-load condition, the main dynamic performance parameters of bridges are slightly larger than conventional condition, but the variation law of vertical acceleration of mid-span is different.

Effects of Temperature Rise of Grease on Lubricating Performance of Drive Elements under the Extreme Pressure

2021 ◽  
Vol 901 ◽  
pp. 187-192
Author(s):  
Yuh Ping Chang ◽  
Li Ming Chu ◽  
Hsiang Yu Wang ◽  
Chien Te Liu ◽  
Qi Wen Chen
Keyword(s):  
Friction Coefficient ◽  
Temperature Rise ◽  
Electrical Contact ◽  
Load Condition ◽  
Extreme Pressure ◽  
Electrical Contact Resistance ◽  
Heavy Load ◽  
Key Technology ◽  
Effects Of Temperature ◽  
Great Stress

To transfer more power and use it in a heavy load environment, the contact surface between the ball and the track must bear great stress. The temperature always rises due to friction, which is more likely to cause problems of material deformation and fatigue failure. As a result, it will be a key technology to maintain a certain lubricating effect of the transmission components under the environment of heavy load and temperature rise. Through the analysis of friction coefficient and electrical contact resistance, the greases are used to test the lubricating effect of the transmission elements under the heavy load condition. The results will be helpful for the industry to use heavy load greases as a reference.

scholarly journals Wear Mechanism of Nomex/PTFE Fiber Reinforced Composites

2021 ◽  
Author(s):  
Jian Liu ◽  
Fei Lu ◽  
Tiantian He ◽  
Xianjuan Pang ◽  
Yongzhen Zhang
Keyword(s):  
Wear Behavior ◽  
Dominant Role ◽  
Load Condition ◽  
Sem Analysis ◽  
Tribological Performance ◽  
High Load ◽  
Fiber Reinforced ◽  
Heavy Load ◽  
Frequency Condition ◽  
Friction Temperature

Abstract This paper is aimed at the problems of abnormal tribological damage and fluctuation of tribological performance in the self-lubricating composite serving in heavy load spherical plain bearing in aerospace field. The Nomex/PTFE fiber reinforced composite was used to carry out a reciprocating block on ring tribological test, investigating the tribological performance of the material and its wear evolution. Results show that the influence of oscillating frequency on material wear is obviously higher than that of load under high load condition (more than 90 MPa or 180 kN). Under a certain load and frequency condition, friction temperature is a key factor to affect wear behavior of the material. Friction heat plays a dominant role in the process of worn out failure of the material. Too high friction temperature greatly weakens the friction and wear performance, resulting in material failure in a short time. Thermal fatigue is the main tribological damage mode of the material under the high load and high frequency condition, with local worn out occurred. This finding was also verified by SEM analysis of the worn surface and wear debris.

Optimum Location of Spvg to Enhance Voltage Stability Using Static Techniques

2020 ◽  
Vol 23 (2) ◽  
pp. 49-58
Author(s):  
Melat K. Abdulla ◽  
Lokman H. Hassan
Keyword(s):  
Power Systems ◽  
New England ◽  
Power Flow ◽  
Voltage Stability ◽  
Load Condition ◽  
Vital Role ◽  
Heavy Load ◽  
The Stability ◽  
The Impact ◽  
Photovoltaic Generators

Solar Photovoltaic Generators (SPVGs) play a great and vital role in providing clean and enough energy to meet power loads. However, SPVGs integration on power systems increase power grid problems. It will lead to different problems including disturbance of the grid, instability of the voltage and swings of the power. The impact of SPVG on the voltage stability of the system is studied in this paper. The best location of SPVG is obtained using three static techniques. Power flow and the Q-V curve techniques are used to identify the weakest buses and test the stability of the system under nominal load condition respectively. On other hand, Continuation Power Flow (CPF) and the Q-V curve techniques are used to identify the weakest buses and test the stability of the system under heavy load condition respectively. The proposed techniques are apllied to the New England 39-bus standard system under various loading conditions. The results reveal that choosing a proper location for the SPVG will improve the voltage stability of the system. In addition, connecting the SPVG at the nearest bus to the weakest bus provides better performance than when it connected to the weakest bus.

scholarly journals A Predictive Study of a New VCR Engine with High Expansion Ratio and High-Efficiency Potential under Heavy Load Conditions

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1655
Author(s):  
Jiansheng Lin ◽  
Shu Yang
Keyword(s):  
Compression Ratio ◽  
Thermal Efficiency ◽  
High Efficiency ◽  
Control Variable ◽  
Load Condition ◽  
Heavy Load ◽  
Variable Compression Ratio ◽  
The Future ◽  
Load Conditions ◽  
Variable Compression

Facing the future, whether working alone or with electric motors, a new type of variable compression ratio (VCR) engine that can achieve a high thermal efficiency under heavy load conditions is necessary. Hence, we propose a dual shaft control variable compression ratio (DSC-VCR) engine based on a gear-driven eccentric sleeve. With the improved position of gears, DSC-VCR allows for double larger gears to share the load, and the engine can operate with a larger eccentric size and a narrower adjustment range compared to other similar mechanisms. This helps to reduce the difficulty of chamber shape design, avoid collisions between valves and piston, and above all, makes the engine operate with a larger overexpansion ratio (OER, the ratio of expansion stroke and compression stroke) under all conditions to improve engine efficiency. Based on a 1.5 T four-cylinder engine, the OER can be increased to over 1.16 with the eccentric size of 6.5 mm. According to the theoretical thermal efficiency calculation while considering turbocharging, the per millimeter increase of eccentric size improves the theoretical efficiency by 0.0025–0.006. The predictive simulation presented that the reduction of residual gas helps to increase the compression ratio (CR) from 9.5 to 10.1 under a full load condition. Larger OERs and CRs help to reduce brake specific fuel consumption (BSFC) by 6%–8%. In the case of a 75% load, about 3.51% of efficiency increase was realized. All of these prove that DSC-VCR is a high-efficiency potential mechanism for the future.

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