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Author(s):  
Manish Kapse

Abstract: Induction motors are used as industrial drive and for various applications in power plant due to their rugged, robust and simple construction as well as low cost. The speed control of SRIM is dexterous by slip power recovery scheme consisting of inverter control, chopper control, and rotor resistance control techniques. This paper presents the boost in the performance characteristics and energy saving of SRIM drive by inverter and buck-boost chopper based slip power recovery scheme (SPRS). The simulation model of a WRIM drive using inverter and based buck-boost chopper control has been executed in the Simulink platform. The simulation results using inverter and chopper control have been studied. The active power and reactive power have been taken as parameter for analyzing the energy saving by the drive. The simulation result has shown that inverter chopper control SPRS large amount of energy saving.


Author(s):  
Gennaro Gelao ◽  
◽  
Roberto Marani ◽  
Anna Gina Perri

In this paper we compare simulation results on a differential pair circuit using a CNTFET model, already proposed by us, with the result obtained using Stanford model. We study the case of differential pair with differential input and single ended output as core of a 50 GHz amplifier for mm waves band. We consider the case of a CNTFET having a single CNT tube with indices (19,0) and 25 nm long. For this circuit we present result for its main parameters: gain, input impedance, output impedance, noise and distortion. Since the Stanford model includes fixed capacitance, for comparison we applied the same capacitance on our model. Since this capacitances dominate the high frequency cut, results are not much different, except for the lack of noise modelling in the Stanford model.


Author(s):  
Qichen Zhang ◽  
Xiaodong Kang ◽  
Huiqing Liu ◽  
Xiaohu Dong ◽  
Jian Wang

AbstractCurrently, the reservoir heterogeneity is a serious challenge for developing oil sands with SAGD method. Nexen’s Long Lake SAGD project reported that breccia interlayer was widely distributed in lower and middle part of reservoir, impeding the steam chamber expansion and heated oil drainage. In this paper, two physical experiments were conducted to study the impact of breccia interlayer on development of steam chamber and production performance. Then, a laboratory scale numerical simulation model was established and a history match was conducted based on the 3D experimental results. Finally, the sensitivity analysis of thickness and permeability of breccia layer was performed. The influence mechanism of breccia layer on SAGD performance was analyzed by comparing the temperature profile of steam chamber and production dynamics. The experimental results indicate that the existence of breccia interlayer causes a thinner steam chamber profile and longer time to reach the peak oil rate. And, the ultimate oil recovery reduced 15.8% due to much oil stuck in breccia interlayer areas. The numerical simulation results show that a lower permeability in breccia layer area has a serious adverse impact on oil recovery if the thickness of breccia layer is larger, whereas the effect of permeability on SAGD performance is limited when the breccia layer is thinner. Besides, a thicker breccia layer can increase the time required to reach the peak oil rate, but has a little impact on the ultimate oil recovery.


2021 ◽  
Author(s):  
Costanza Bonadonna ◽  
Ali Asgary ◽  
Franco Romerio ◽  
Tais Zulemyan ◽  
Corine Frischknecht ◽  
...  

Abstract. Evacuation planning and management represents a key aspect of volcanic crises because it can increase people protection as well as minimize the potential impact on the economy, properties, and infrastructure of the affected area. Assessment of evacuation scenarios that consider human and economic impact is best done in a pre-disaster context as it helps authorities develop evacuation plans and make informed decisions outside the highly stressful time period that characterizes crises. We present an agent-based simulation tool that assesses the effectiveness of different evacuation scenarios using Vulcano island (Italy) as a case study. Simulation results show that the overall time needed to evacuate people should be analysed together with the percentage of people evacuated as a function of time and that a simultaneous evacuation on Vulcano is more efficient than a staged evacuation. We also present a model to assess the economic impact of evacuation as a function of evacuation duration and starting period that reveals that an evacuation of Vulcano would cause significant economic impact to the tourism industry if lasting more than 3 months (in case it was initiated at the beginning of the visitor season) to 1 year (in case it was initiated at the end of the visitor season).


2021 ◽  
Vol 9 ◽  
Author(s):  
Shuaigang Liu ◽  
Jianbiao Bai ◽  
Xiangyu Wang ◽  
Guanghui Wang ◽  
Bowen Wu ◽  
...  

The double-roadway layout system, which is extensively applied in large mines, has the potential to significantly balance excavation-mining and improve mine ventilation and transportation capacity. However, the coal pillar in the double-roadway layout system is easily destabilized due to the disturbance of repeated mining, which has a significant impact on the safety and reliability of coal mines. This paper takes the coal pillar and its supporting structure of the double-roadway layout system as the research object, establishes a UDEC trigon numerical calculation model, and systematically corrects the input parameters, while explaining the excavation method of roadways and the simulation method of the supporting structure element. The numerical simulation results show that under the conventional support intensity conditions, the internal damage of the coal pillar during the excavation period is about 20%, while the internal damage to the coal pillar develops to 55% throughout the first-panel mining. During the disturbance of repeated mining, the damage in the coal pillar increased to 90%, and the coal pillar was already in a state of failure. Under the combined control of rock bolts and counter-pulled anchor cables, the coal pillar damage does not change significantly during the excavation and first-panel mining. During the disturbance of repeated mining, the damage of the coal pillar is reduced to 63%. There is a certain low damage area in the coal pillar, which can ensure the stability of the coal pillar and its supporting structure as a whole. Furthermore, the on-site monitoring results show that the maximum value of the floor-to-roof and rib-to-rib convergence of a W1310 tailgate during the repeated mining disturbance stage is 730 and 620 mm, respectively. The findings of this study give an approach to—as well as estimated values for the design of, including its “small structure” control technical parameters—the double-roadway layout system.


2021 ◽  
Vol 11 (20) ◽  
pp. 9559
Author(s):  
Junzhe Lin ◽  
Yuanyuan Wang ◽  
Shenghao Zhou ◽  
Wenjie Wu ◽  
Hui Ma ◽  
...  

The output flow pulsation characteristics of the hydraulic pump due to the structural characteristics may cause pump source fluid pressure pulsation and even cause the equipment to vibrate, which will affect the life and working reliability of the equipment. Scholars have done a lot of theoretical and simulation analysis on the characteristics of fluid flow and pressure pulsation caused by the specific structure and structure of the plunger pump, but there are few comparisons and analyses of the simplified model of the plunger pump and the pressure pulsation characteristics with experiments. In this paper, AMESim software is utilized to establish a simplified model of one seven-plunger hydraulic pump, and simulate and analyze the pump source fluid pressure pulsation characteristics of different system load pressures at a constant speed. An experimental platform for testing pump fluid pressure pulsation was designed and built, and the actual measurement and simulation results of pump fluid pressure pulsation were compared and analyzed. The results show that the system simulation data is in good agreement with the measured data, which verifies the correctness of the simplified model of the plunger pump. At the same time, it is found that the fluid pressure pulsation of the pump source exhibits broadband and multi-harmonic characteristics. At a constant speed, as the load pressure of the hydraulic system increases, the pump source fluid pressure pulsation amplitude increases, the pressure pulsation rate decreases, and the impact on the fundamental frequency amplitude is the most significant. The research results can provide a theoretical basis for suppressing the pressure pulsation of the pump source fluid and reducing the vibration response of a hydraulic pipeline under the action of the pulsating harmonic excitation.


Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6677
Author(s):  
N. I. Koteleva ◽  
N. A. Korolev ◽  
Y. L. Zhukovskiy

The paper discusses the method of identifying the technical condition of induction motors by classifying the energy data coming from the main common power bus. The work shows the simulation results of induction motor operation. The correlation between occurring defects and current diagrams is presented. The developed simulation model is demonstrated. The general algorithm for conducting experiments is described. Five different experiments to develop an algorithm for the classification are conducted: determination of the motors number in operation with different power; determination of the motors number in operation with equal power; determination of the mode and load of induction electric motor; determination of the fault and its magnitude with regard to operation and load of induction motor; determination of the fault and its magnitude with regard to operation and load of induction motor with regard to non-linear load in the flow. The article also presents an algorithm for preprocessing data to solve the classification problem. In addition, the classification results are shown and recommendations for testing and using the classification algorithm on a real object are made.


Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2709
Author(s):  
Jiajia Qian ◽  
Jun Zhou ◽  
Zheng Zhu ◽  
Zhenzhen Ge ◽  
Shuting Wu ◽  
...  

A polarization-insensitive broadband terahertz absorber based on single-layer graphene metasurface has been designed and simulated, in which the graphene metasurface is composed of isolated circular patches. After simulation and optimization, the absorption bandwidth of this absorber with more than 90% absorptance is up to 2 THz. The simulation results demonstrate that the broadband absorption can be achieved by combining the localized surface plasmon (LSP) resonances on the graphene patches and the resonances caused by the coupling between them. The absorption bandwidth can be changed by changing the chemical potential of graphene and the structural parameters. Due to the symmetrical configuration, the proposed absorber is completely insensitive to polarization and have the characteristics of wide angle oblique incidence that they can achieve broadband absorption with 70% absorptance in the range of incident angle from 0° to 50° for both TE and TM polarized waves. The flexible and simple design, polarization insensitive, wide-angle incident, broadband and high absorption properties make it possible for our proposed absorber to have promising applications in terahertz detection, imaging and cloaking objects.


2021 ◽  
Vol 11 (20) ◽  
pp. 9560
Author(s):  
Yi-Fei Lu ◽  
Mu-Sheng Jiang ◽  
Yang Wang ◽  
Xiao-Xu Zhang ◽  
Fan Liu ◽  
...  

The twin-field quantum key distribution (TF-QKD) and its variants can overcome the fundamental rate-distance limit of QKD. However, their physical implementations with the side channels remain the subject of further research. We test the side channel of a type of external intensity modulation that applies a Mach–Zehnder-type electro-optical intensity modulator, which shows the distinguishability of the signal and decoy states in the frequency domain. Based on this security loophole, we propose a side-channel attack, named the passive frequency-shift attack, on the imperfect implementation of the sending or not-sending (SNS) TF-QKD protocol. We analyze the performance of the SNS protocol with the actively odd-parity pairing (AOPP) method under the side-channel attack by giving the formula of the upper bound of the real secret key rate and comparing it with the lower bound of the secret key rate under Alice and Bob’s estimation. The simulation results quantitatively show the effectiveness of the attack on the imperfect devices at a long distance. Our results emphasize the importance of practical security at the light source and might provide a valuable reference for device selection in the practical implementation of the SNS protocol.


2021 ◽  
Vol 16 (3) ◽  
pp. 128-141
Author(s):  
A. M. Tleppayev ◽  
S. Zh. Zeinolla

The purpose of this study is to study the approaches to measuring the indicators of the circular economy used in the countries of the European Union and in the OECD countries to form an understanding of the applicability of the presented methods. The study used the methods of econometric modeling, statistical and comparative analyzes. A model was built using data for the European Union countries, the following variables (factors) were used to build this model: the share of material extracted and returned to the economy, the intensity of CO2 emissions, the level of energy intensity of primary energy, GDP per capita, research and development costs, the share urban population in total. Based on the simulation results, it was concluded that GDP growth and growth in energy intensity, together with an increase in the level of technology in the economy, leads to an increase in the processing of materials and their reuse in economic circulation. The results of modelling confirm the conclusions of the previous authors, the analysis of the strategies of the EU and OECD countries. It is necessary to invest more financial resources in R&D, development of new technologies and innovations for achieve better results. Greater involvement of consumers and businesses in activities conducive to the circular economy is also critical. Achieving these two goals will contribute to sustainable economic development. Based on the analysis of the model and strategies of the OECD and EU countries on the circular economy, we concluded that international innovations in the circular economy are applicable to Kazakhstan’s economy.


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