An explosion-proof dual throttling air-conditioning system was put forward to solve the heat dissipation and internal dewing problems of explosion-proof frequency converter in the underground coal mine. This study inv...An explosion-proof dual throttling air-conditioning system was put forward to solve the heat dissipation and internal dewing problems of explosion-proof frequency converter in the underground coal mine. This study investigated the feasibility and benefits of explosion-proof dual throttling cooling and dehumidification air-conditioning system applied to the explosion-proof frequency converter. The physical model of dual throttling air-conditioning system was established and its performance parameter was described by mathematical method. The design calculation of the system has also been done. The experimental result showed that the system reached the steady state at the refrigeration mode after running 45 min, and the maximum internal temperature of the flame-proof cavity was 31.0 ℃. The system reached the steady state at the dehumidification mode after running 37 min. The maximum internal relative humidity and temperature of the flame-proof cavity were 33.4% and 36.3 ℃, respectively. Therefore, the proposed system had excellent ability of heat dissipation and avoided internal dewing. Compared with water cooling system, it was more energy-saving and economical. The airflow field of dual throttling air-conditioning system was also studied by CFD simulation. It was found that the result of CFD numerical simulation was highly consistent with the experimental data.展开更多
Multi stage and multi orifice throttling analysis for bypass valves in thermal power generating sets is important for normal operation of power generating equipment. It is improper to exclude the factor of flow resist...Multi stage and multi orifice throttling analysis for bypass valves in thermal power generating sets is important for normal operation of power generating equipment. It is improper to exclude the factor of flow resistance from the expansion coefficient for the flow formula used for analysing the multi stage and multi orifice flow of compressible fluid, which means expansion of gas has nothing to do with resistance. The authors put forward an expanded energy equation and related formula to overcome the drawback, and use them for multi stage and multi orifice throttling analysis of compressible fluid for thermal power generating sets.展开更多
In this work an experimental investigation was carried out in order to explore the possibility of realizing a domestic heating system by throttling hydraulic oil. Considering the continuous increasing price of diesel ...In this work an experimental investigation was carried out in order to explore the possibility of realizing a domestic heating system by throttling hydraulic oil. Considering the continuous increasing price of diesel oil, this work gains unique importance. Generating heat directly by throttling is realized using a simple environment friendly system which does not require oil transportation and storage, and eliminates the need for chimneys and annual preventive maintenance, as it is the case with heating by utilizing oil burners, which is prevailing in Jordan. Experimental results show that it is possible to raise the room temperature up to 70?C during 15 minutes which is not a limit value. Experimental results show that temperature rate could be increased by selecting the appropriate pump power and by connecting a number of throttles in parallel.展开更多
Hollow cathode discharges are widely used as neutralizers for the electric propulsion systems and recently developed into micro-thrusters for the small satellites.In this work,a dualemitter hollow cathode thruster is ...Hollow cathode discharges are widely used as neutralizers for the electric propulsion systems and recently developed into micro-thrusters for the small satellites.In this work,a dualemitter hollow cathode thruster is developed,which can be operated in two different modes—the neutralizer mode and the micro-thruster mode.For characterizing this kind of new device,the Langmuir probe,Faraday probe,and retarding potential analyzer are used to determine the electron temperature,electron density,ion flux,and ion energy distribution function.The operating parameters,including the thrust,and specific impulse,are also measured.A two-dimensional self-consistent extended fluid model is employed to calculate the spatial distribution of plasma parameters and the fluid field of electrons in the region around the emitters.By comparing the diagnostic and modelling results,it is found that the change in the electric field and ionization zone is the essential reason for the different performances of the device in the neutralizer and micro-thruster modes.Variation in the electric field leads to an ion acceleration effect in the micro-thruster mode;moving of the ionization zone raises the plasma pressure in the orifice region of the hollow cathode,and thus leads to enhanced plasma throttling and gas expanding effects.By analyzing the above mechanisms,the possible methods for improving this kind of hollow cathode micro-thruster are discussed.展开更多
In order to reduce the non production time of drilling,improve the efficiency and safety of drilling,improve the economic effect of managed pressure drilling(MPD),and realize the intelligent control construction of di...In order to reduce the non production time of drilling,improve the efficiency and safety of drilling,improve the economic effect of managed pressure drilling(MPD),and realize the intelligent control construction of digital oilfield.Based on the pressure control in MPD,this paper analyzes the pressure control drilling system,takes the wellhead back pressure as the controlled parameter,calculates the mathematical model of the throttle valve according to the characteristics of the throttle valve,the basic parameters and boundary conditions of pressure control drilling,and puts forward an improved particle swarm Optimization PID neural network(IPSO-PIDNN)model.By means of remote communication,VR technology can realize remote control of field control equipment.The real-time control results of IPSO-PIDNN are compared with those of traditional PID neural network(PIDNN)and traditional Particle Swarm Optimization PID neural network(PSO-PIDNN).The results show that IPSO-PIDNN model has good self-learning characteristics,high optimization quality,high control accuracy,no overshoot,fast response and short regulation time.Thus,the advanced automatic control of bottom hole pressure in the process of MPD is realized,which provides technical guarantee for the well control safety of MPD.展开更多
For the pressure enthalpy of high pressure pneumatics, the computational fluid dynamics(CFD)simulation based on ideal gas assumption fails to obtain the real temperature information. Therefore, we propose a method to ...For the pressure enthalpy of high pressure pneumatics, the computational fluid dynamics(CFD)simulation based on ideal gas assumption fails to obtain the real temperature information. Therefore, we propose a method to compensate the pressure enthalpy of throttling for CFD simulation based on ideal gas assumption.Firstly, the pressure enthalpy is calculated for the pressure range of 0.101 to 30 MPa and the temperature range of 190 to 298 K based on Soave-Redlich-Kwong(S-R-K) equation. Then, a polynomial fitting equation is applied to practical application in the above mentioned range. The basic idea of the compensation method is to convert the pressure enthalpy difference between inlet air and nodes into the compensation temperature. In the above temperature and pressure range, the compensated temperature is close to the real one, and the relative temperature drop error is below 10%. This error is mainly caused by the velocity difference of the orifice between the real and ideal gas models. Finally, this compensation method performs an icing analysis for practical high pressure slide pilot valve.展开更多
Cloud Technology is a new platform that offers on-demand computing Peripheral such as storage,processing power,and other computer system resources.It is also referred to as a system that will let the consumers utilize...Cloud Technology is a new platform that offers on-demand computing Peripheral such as storage,processing power,and other computer system resources.It is also referred to as a system that will let the consumers utilize computational resources like databases,servers,storage,and intelligence over the Internet.In a cloud network,load balancing is the process of dividing network traffic among a cluster of available servers to increase efficiency.It is also known as a server pool or server farm.When a single node is overwhelmed,balancing the workload is needed to manage unpredictable workflows.The load balancer sends the load to another free node in this case.We focus on the Balancing of workflows with the proposed approach,and we present a novel method to balance the load that manages the dynamic scheduling process.One of the preexisting load balancing techniques is considered,however it is somewhat modified to fit the scenario at hand.Depending on the experimentation’s findings,it is concluded that this suggested approach improves load balancing consistency,response time,and throughput by 6%.展开更多
Models that simulate the signature of single airguns form the basis for modelingthe signals of airgun arrays. Most of the existing models assume that the air inside theproduced bubble is ideal gas, which may lead to e...Models that simulate the signature of single airguns form the basis for modelingthe signals of airgun arrays. Most of the existing models assume that the air inside theproduced bubble is ideal gas, which may lead to errors because of the high operating pressureof the airguns. In this study, we propose a model that precisely simulates the signals of singleairguns by applying the Van der Waals equation based on the Ziolkowski algorithm. We alsoconsider a thermodynamically open quasistatic system, the heat transition between waterand gas, the throttling effect of the port and the bubble rise, and the effect of the sea surface.Modeling experiments show that (1) the energy of the source increases and the signal-to-noise ratio of the signature wavelet decreases with increasing seawater temperature, (2) thereflection coefficient of the sea surface under the actual state and depth of the source affectsthe notch caused by the surface reflection, (3) the computed signature with the proposedmodel is very close to the actual data, and (4) the proposed model accurately simulates thesignature of sinale air^uns.展开更多
Exhaust thermal management is essential to allow engines to meet the Euro VI emissions standards and reducing nitrogen oxide emissions is one of the most important targets being pursued nowadays.Along these lines,in t...Exhaust thermal management is essential to allow engines to meet the Euro VI emissions standards and reducing nitrogen oxide emissions is one of the most important targets being pursued nowadays.Along these lines,in the present study,engine’s thermal performances have been evaluated on the basis of a WHTC test,namely a transient engine dynamometer schedule defined by the global technical regulation(GTR)developed by the UN ECE GRPE group(the GTR is covering a world-wide harmonized heavy-duty certification(WHDC)procedure for engine exhaust emissions).The influence of thermal management on fuel consumption,intake,and tailpipe NO_(x) have been quantitatively analyzed for the overrun state.The results have shown that there can be a strong influence on the after-treatment temperatures and tailpipe NO_(x).In particular,the average temperature upstream of the diesel oxidation catalyst(DOC)has been found to increase from 245°C to 254°C,the average temperature of the selective catalytic reduction(SCR)to increase from 248°C to 253°C,the SCR’s minimum temperature to increase from 196°C to 204°C,and the peak value of the NO_(x) emissions in the low-temperature region to decrease from 73 to 51 mg/s.However,the influence of the overrun state’s thermal management strategy on the fuel consumption,the air intake,the ammonia storage,the NO_(2)/NO_(x) ratio,and the urea consumption has been observed to be relatively limited.展开更多
Throttling of large-thrust liquid rocket engines,which can improve mission adaptability of a carrier rocket,reduce risk and facilitate rocket recovery,is a key technology for current and future space development.This ...Throttling of large-thrust liquid rocket engines,which can improve mission adaptability of a carrier rocket,reduce risk and facilitate rocket recovery,is a key technology for current and future space development.This paper summarizes the state of the art and trends of throttling technology for large-thrust liquid rocket engines at home and abroad.According to the working principles of propulsion for rocket engines,throttling the propellant flow rate is a major way of adjusting thrust,and regulation devices along with adjustable injectors are primary measures of throttling propellant flow rates.This paper clarifies the working principles of typical regulation devices and adjustable injectors,introduces the regulation schemes of typical large-thrust engines such as YF-100,RD-170,and SSME,and summarizes the main characteristics of current throttleable large-thrust engines.Finally,critical technologies and development trends of throttling are discussed,including combustion stability and reliable cooling of thrust chambers at low thrust levels,turbopump stability,and stable regulation and precise control in a wide range of operating conditions.展开更多
There are two very common sayings about corpse (dead body). The first common saying is that “the corpse is a silent witness who never lies” and the other common saying is that “the dead body is extremely eloquent a...There are two very common sayings about corpse (dead body). The first common saying is that “the corpse is a silent witness who never lies” and the other common saying is that “the dead body is extremely eloquent and honestly informative, if one exercises patience in listening to it.” Both these sayings were proved in one of our cases. In the present case, decomposed body of an unidentified female individual aged about 25 - 26 years was recovered from the bank of western Yamuna canal in Haryana. The police made the efforts for establishing the identity of the deceased but could not succeed. The body was forwarded to the district hospital for autopsy along with the inquest report. However, the body being in advanced stage of decomposition so it was referred from the district hospital to the department of Forensic Medicine, PGIMS, Rohtak (Haryana) for the examination and the expert opinion regarding the cause of death. The findings observed on examination of the body helped to deduce the cause, time and manner of death whereas certain important objective features of identification were also observed and ultimately proper identity of the deceased could be established beyond the reasonable doubt by DNA profile of the samples preserved at autopsy. The autopsy findings, DNA profile and the results of examination of other materials (exhibits) taken from the body not only revealed the truth from the silent witness—the corpse, but also provided objective and scientific evidence to establish the corpus delicti in this case.展开更多
In modern vehicles, electronic throttle(ET) has been widely utilized to control the airflow into gasoline engine. To solve the control difficulties with an ET, such as strong nonlinearity,unknown model parameters and ...In modern vehicles, electronic throttle(ET) has been widely utilized to control the airflow into gasoline engine. To solve the control difficulties with an ET, such as strong nonlinearity,unknown model parameters and input saturation constraints,an adaptive sliding-mode tracking control strategy for an ET is presented. Compared with the existing control strategies for an ET, input saturation constraints and parameter uncertainties are adequately considered in the proposed control strategy. At first, the nonlinear dynamic model for control of an ET is described. According to the dynamical model, the nonlinear adaptive sliding-mode tracking control method is presented,where parameter adaptive laws and auxiliary design system are employed. Parameter adaptive law is given to estimate the unknown parameter with an ET. An auxiliary system is designed,and its state is utilized in the tracking control method to handle the input saturation. Stability proof and analysis of the adaptive sliding-mode control method is performed by using Lyapunov stability theory. Finally, the reliability and feasibility of the proposed control strategy are evaluated by computer simulation.Simulation research shows that the proposed sliding-mode control strategy can provide good control performance for an ET.展开更多
Based on the solution of the governing differential equation for deformation of throttle slice while satisfying required boundary conditions, the coefficient (Gr) and an analytical formula for computing the deformat...Based on the solution of the governing differential equation for deformation of throttle slice while satisfying required boundary conditions, the coefficient (Gr) and an analytical formula for computing the deformation of throttle slice is presented through equivalency transformation, which is a concise, accurate and practical method for throttle slice design and characteristic analysis. Researched the deformation at any radius, compared with ANSYS FEA software by the simulation analysis, the availability opening size of throttle that was defined by the deformation at the valve mouth radius is studied. The affection of valve mouth radius to the damper characteristic is analyzed. Tests are made for the damper characteristic, compared with simulation results, it is shown that Gr method is an accurate computation method for computing the deformation of throttle slice at valve mouth radius, suitihle to use in the damper design, analysis, and verification. The deformation at mouth radius could not be replaced with the outside radius.展开更多
In order to effectively implement DPF(Diesel Particulate Filters)regeneration control,thermal management of exhaust products before and inside Diesel Oxidation Catalyst(DOC)is necessary.In the present study,the Influe...In order to effectively implement DPF(Diesel Particulate Filters)regeneration control,thermal management of exhaust products before and inside Diesel Oxidation Catalyst(DOC)is necessary.In the present study,the Influence of the intake throttle valve and late post injection process on temperature rise inside DOC is analyzed through engine bench tests.The steady experiment results show that adjustment of the intake throttle valve can effectively increase exhaust temperature before DOC;in particular,with intake throttle valve opening at 20%,temperature before DOC can be increased by about 170℃ with respect to the full opening.An increase in the late post injection quantity can produce a significant rise of the temperature inside DOC,however its impact on the exhaust temperature before DOC is relatively limited.As the late post injection quantity increases,Hydrocarbon(HC)emissions also grow;in the present work it is shown that with a proper injection quantity,a considerable temperature increase inside the DOC can be obtained with relatively low HC emission.More specifically,with the intake throttle valve at 30%and DOC reaching ignition temperature as the late post injection quantity is increased,the exhaust temperature after DOC can be made larger than 550℃,adequate for DPF active regeneration.展开更多
Experimental investigations are made on the effects of operating conditionson the flow characteristics of throttle when tap water is used as the working media. The researchedthrottles include cone poppet valve, ball v...Experimental investigations are made on the effects of operating conditionson the flow characteristics of throttle when tap water is used as the working media. The researchedthrottles include cone poppet valve, ball valve, disc valve and dumping orifice. Operating conditionincludes poppet lift, working media, back pressure, medium temperature, etc. Because the vapourouspressure of water is much higher than that of oil, cavitation is easier to occur in water hydraulicelements and systems, so the effects of operating conditions on the cavitation characteristics ofthrottle are also researched.展开更多
A new longitudinal control strategy for vehicle adaptive cruise control (ACC) systems is presented. The running relationship between the ACC vehicle and the detected target vehicle is described by the relative veloc...A new longitudinal control strategy for vehicle adaptive cruise control (ACC) systems is presented. The running relationship between the ACC vehicle and the detected target vehicle is described by the relative velocity and the deviation between the actual headway distance and the prescribed safety distance. Based on this, two state space models are built and the linear quadratic optimal control theory is used to yield desired velocity for the ACC-equipped vehicle when with the target vehicle detected. By switching among four control modes, the desired velocity profile is designed to deal with different running situations. A velocity controller, which includes a PID controller for throttle openness and a neural network controller for brake application, is developed to achieve the desired velocity profile. The proposed control strategy is applied to a non-linear vehicle model in a simulation environment and is shown to provide the ACC vehicle comfortable ride and satisfying safety.展开更多
Combining with the development of automated manual transmission (AMT), the various throttle control demands are analyzed under different working conditions of AMT such as tracking acceleration pedal, start, shift an...Combining with the development of automated manual transmission (AMT), the various throttle control demands are analyzed under different working conditions of AMT such as tracking acceleration pedal, start, shift and so on. Based on simulation, the responding throttle control strategies are proposed, and a simple but effective throttle control method is presented. The testing results have proved that the strategies are effective for improving the pedal tracking precision and the qualities of start and shift.展开更多
In allusion to easy invalidation of damping valve in vehicle shock absorber caused by the impact from the road surface, the importance of the study of damping valve water hammer pressure is presented. The physical mod...In allusion to easy invalidation of damping valve in vehicle shock absorber caused by the impact from the road surface, the importance of the study of damping valve water hammer pressure is presented. The physical model of damping valve with the circle throttle slice is established. The time for the throttle slice deformation is studied by using the finite software, and the laws that how the structure parameters affect the deformation time are obtained. Combining the theory of water hammer, the water hammer initial and boundary condition of the damping valve is deduced, and the water hammer model of throttle slice is established. The analysis of simulation results indicates that the water hammer pressure amplitude and the amount of water hammer oscillation period can be reduced and the dependability of the valve can be enhanced by modifying the structure parameters and aperture width between slice and valve body.展开更多
基金Supported by the National Basic Research Program of China("973"Program,No.2009CB219907)
文摘An explosion-proof dual throttling air-conditioning system was put forward to solve the heat dissipation and internal dewing problems of explosion-proof frequency converter in the underground coal mine. This study investigated the feasibility and benefits of explosion-proof dual throttling cooling and dehumidification air-conditioning system applied to the explosion-proof frequency converter. The physical model of dual throttling air-conditioning system was established and its performance parameter was described by mathematical method. The design calculation of the system has also been done. The experimental result showed that the system reached the steady state at the refrigeration mode after running 45 min, and the maximum internal temperature of the flame-proof cavity was 31.0 ℃. The system reached the steady state at the dehumidification mode after running 37 min. The maximum internal relative humidity and temperature of the flame-proof cavity were 33.4% and 36.3 ℃, respectively. Therefore, the proposed system had excellent ability of heat dissipation and avoided internal dewing. Compared with water cooling system, it was more energy-saving and economical. The airflow field of dual throttling air-conditioning system was also studied by CFD simulation. It was found that the result of CFD numerical simulation was highly consistent with the experimental data.
文摘Multi stage and multi orifice throttling analysis for bypass valves in thermal power generating sets is important for normal operation of power generating equipment. It is improper to exclude the factor of flow resistance from the expansion coefficient for the flow formula used for analysing the multi stage and multi orifice flow of compressible fluid, which means expansion of gas has nothing to do with resistance. The authors put forward an expanded energy equation and related formula to overcome the drawback, and use them for multi stage and multi orifice throttling analysis of compressible fluid for thermal power generating sets.
文摘In this work an experimental investigation was carried out in order to explore the possibility of realizing a domestic heating system by throttling hydraulic oil. Considering the continuous increasing price of diesel oil, this work gains unique importance. Generating heat directly by throttling is realized using a simple environment friendly system which does not require oil transportation and storage, and eliminates the need for chimneys and annual preventive maintenance, as it is the case with heating by utilizing oil burners, which is prevailing in Jordan. Experimental results show that it is possible to raise the room temperature up to 70?C during 15 minutes which is not a limit value. Experimental results show that temperature rate could be increased by selecting the appropriate pump power and by connecting a number of throttles in parallel.
基金supported by the National Natural Science Foundation of China(Nos.61571166,11775063 and 51736003)。
文摘Hollow cathode discharges are widely used as neutralizers for the electric propulsion systems and recently developed into micro-thrusters for the small satellites.In this work,a dualemitter hollow cathode thruster is developed,which can be operated in two different modes—the neutralizer mode and the micro-thruster mode.For characterizing this kind of new device,the Langmuir probe,Faraday probe,and retarding potential analyzer are used to determine the electron temperature,electron density,ion flux,and ion energy distribution function.The operating parameters,including the thrust,and specific impulse,are also measured.A two-dimensional self-consistent extended fluid model is employed to calculate the spatial distribution of plasma parameters and the fluid field of electrons in the region around the emitters.By comparing the diagnostic and modelling results,it is found that the change in the electric field and ionization zone is the essential reason for the different performances of the device in the neutralizer and micro-thruster modes.Variation in the electric field leads to an ion acceleration effect in the micro-thruster mode;moving of the ionization zone raises the plasma pressure in the orifice region of the hollow cathode,and thus leads to enhanced plasma throttling and gas expanding effects.By analyzing the above mechanisms,the possible methods for improving this kind of hollow cathode micro-thruster are discussed.
基金This paper is supported by Sichuan applied basic research fund(No.2016JY0049).
文摘In order to reduce the non production time of drilling,improve the efficiency and safety of drilling,improve the economic effect of managed pressure drilling(MPD),and realize the intelligent control construction of digital oilfield.Based on the pressure control in MPD,this paper analyzes the pressure control drilling system,takes the wellhead back pressure as the controlled parameter,calculates the mathematical model of the throttle valve according to the characteristics of the throttle valve,the basic parameters and boundary conditions of pressure control drilling,and puts forward an improved particle swarm Optimization PID neural network(IPSO-PIDNN)model.By means of remote communication,VR technology can realize remote control of field control equipment.The real-time control results of IPSO-PIDNN are compared with those of traditional PID neural network(PIDNN)and traditional Particle Swarm Optimization PID neural network(PSO-PIDNN).The results show that IPSO-PIDNN model has good self-learning characteristics,high optimization quality,high control accuracy,no overshoot,fast response and short regulation time.Thus,the advanced automatic control of bottom hole pressure in the process of MPD is realized,which provides technical guarantee for the well control safety of MPD.
基金the National Natural Science Foundation of China(No.51205421)the Fund of the Key Laboratory of Sensing Technology and Biomedical Instruments of Guangdong Province(No.2011A060901013)
文摘For the pressure enthalpy of high pressure pneumatics, the computational fluid dynamics(CFD)simulation based on ideal gas assumption fails to obtain the real temperature information. Therefore, we propose a method to compensate the pressure enthalpy of throttling for CFD simulation based on ideal gas assumption.Firstly, the pressure enthalpy is calculated for the pressure range of 0.101 to 30 MPa and the temperature range of 190 to 298 K based on Soave-Redlich-Kwong(S-R-K) equation. Then, a polynomial fitting equation is applied to practical application in the above mentioned range. The basic idea of the compensation method is to convert the pressure enthalpy difference between inlet air and nodes into the compensation temperature. In the above temperature and pressure range, the compensated temperature is close to the real one, and the relative temperature drop error is below 10%. This error is mainly caused by the velocity difference of the orifice between the real and ideal gas models. Finally, this compensation method performs an icing analysis for practical high pressure slide pilot valve.
基金supported by the project:“Research and Implementation of Innovative Solutions for Monitoring Consumption in Technical Installations Using Artificial Intelligence”,beneficiary S.C.REMONI TECHNOLOGIES RO S.R.L in partnership with“Gheorghe Asachi”Technical University of Iasi,Financing Contract No.400/390076/26.11.2021,SMIS Code 121866,financed by POC/163/1/3.
文摘Cloud Technology is a new platform that offers on-demand computing Peripheral such as storage,processing power,and other computer system resources.It is also referred to as a system that will let the consumers utilize computational resources like databases,servers,storage,and intelligence over the Internet.In a cloud network,load balancing is the process of dividing network traffic among a cluster of available servers to increase efficiency.It is also known as a server pool or server farm.When a single node is overwhelmed,balancing the workload is needed to manage unpredictable workflows.The load balancer sends the load to another free node in this case.We focus on the Balancing of workflows with the proposed approach,and we present a novel method to balance the load that manages the dynamic scheduling process.One of the preexisting load balancing techniques is considered,however it is somewhat modified to fit the scenario at hand.Depending on the experimentation’s findings,it is concluded that this suggested approach improves load balancing consistency,response time,and throughput by 6%.
基金This research is financially supported by the National Science Foundation Project (Grant No. 41176077, 41230318) and the National 973 Program (Grant No. 2009CB219505).
文摘Models that simulate the signature of single airguns form the basis for modelingthe signals of airgun arrays. Most of the existing models assume that the air inside theproduced bubble is ideal gas, which may lead to errors because of the high operating pressureof the airguns. In this study, we propose a model that precisely simulates the signals of singleairguns by applying the Van der Waals equation based on the Ziolkowski algorithm. We alsoconsider a thermodynamically open quasistatic system, the heat transition between waterand gas, the throttling effect of the port and the bubble rise, and the effect of the sea surface.Modeling experiments show that (1) the energy of the source increases and the signal-to-noise ratio of the signature wavelet decreases with increasing seawater temperature, (2) thereflection coefficient of the sea surface under the actual state and depth of the source affectsthe notch caused by the surface reflection, (3) the computed signature with the proposedmodel is very close to the actual data, and (4) the proposed model accurately simulates thesignature of sinale air^uns.
基金This work was supported by the Natural Science Foundation Project of Shandong Provincial(Grant No.ZR2019MEE041)the open funds of National Engineering Laboratory of Mobile Source Emission Control Technology(Grant No.NELMS2019A01)。
文摘Exhaust thermal management is essential to allow engines to meet the Euro VI emissions standards and reducing nitrogen oxide emissions is one of the most important targets being pursued nowadays.Along these lines,in the present study,engine’s thermal performances have been evaluated on the basis of a WHTC test,namely a transient engine dynamometer schedule defined by the global technical regulation(GTR)developed by the UN ECE GRPE group(the GTR is covering a world-wide harmonized heavy-duty certification(WHDC)procedure for engine exhaust emissions).The influence of thermal management on fuel consumption,intake,and tailpipe NO_(x) have been quantitatively analyzed for the overrun state.The results have shown that there can be a strong influence on the after-treatment temperatures and tailpipe NO_(x).In particular,the average temperature upstream of the diesel oxidation catalyst(DOC)has been found to increase from 245°C to 254°C,the average temperature of the selective catalytic reduction(SCR)to increase from 248°C to 253°C,the SCR’s minimum temperature to increase from 196°C to 204°C,and the peak value of the NO_(x) emissions in the low-temperature region to decrease from 73 to 51 mg/s.However,the influence of the overrun state’s thermal management strategy on the fuel consumption,the air intake,the ammonia storage,the NO_(2)/NO_(x) ratio,and the urea consumption has been observed to be relatively limited.
文摘Throttling of large-thrust liquid rocket engines,which can improve mission adaptability of a carrier rocket,reduce risk and facilitate rocket recovery,is a key technology for current and future space development.This paper summarizes the state of the art and trends of throttling technology for large-thrust liquid rocket engines at home and abroad.According to the working principles of propulsion for rocket engines,throttling the propellant flow rate is a major way of adjusting thrust,and regulation devices along with adjustable injectors are primary measures of throttling propellant flow rates.This paper clarifies the working principles of typical regulation devices and adjustable injectors,introduces the regulation schemes of typical large-thrust engines such as YF-100,RD-170,and SSME,and summarizes the main characteristics of current throttleable large-thrust engines.Finally,critical technologies and development trends of throttling are discussed,including combustion stability and reliable cooling of thrust chambers at low thrust levels,turbopump stability,and stable regulation and precise control in a wide range of operating conditions.
文摘There are two very common sayings about corpse (dead body). The first common saying is that “the corpse is a silent witness who never lies” and the other common saying is that “the dead body is extremely eloquent and honestly informative, if one exercises patience in listening to it.” Both these sayings were proved in one of our cases. In the present case, decomposed body of an unidentified female individual aged about 25 - 26 years was recovered from the bank of western Yamuna canal in Haryana. The police made the efforts for establishing the identity of the deceased but could not succeed. The body was forwarded to the district hospital for autopsy along with the inquest report. However, the body being in advanced stage of decomposition so it was referred from the district hospital to the department of Forensic Medicine, PGIMS, Rohtak (Haryana) for the examination and the expert opinion regarding the cause of death. The findings observed on examination of the body helped to deduce the cause, time and manner of death whereas certain important objective features of identification were also observed and ultimately proper identity of the deceased could be established beyond the reasonable doubt by DNA profile of the samples preserved at autopsy. The autopsy findings, DNA profile and the results of examination of other materials (exhibits) taken from the body not only revealed the truth from the silent witness—the corpse, but also provided objective and scientific evidence to establish the corpus delicti in this case.
基金supported by the National Natural Science Foundation of China (Grant No.50539070)the Major State Basic Research Development Program of China (Grant No.2006CB403304)
基金partially supported by the National Natural Science Foundation of China(61773189)Natural Science Fundamental of Liaoning Province(20170540443)the Program for Liaoning Innovative Research Team in University(LT2016006)
文摘In modern vehicles, electronic throttle(ET) has been widely utilized to control the airflow into gasoline engine. To solve the control difficulties with an ET, such as strong nonlinearity,unknown model parameters and input saturation constraints,an adaptive sliding-mode tracking control strategy for an ET is presented. Compared with the existing control strategies for an ET, input saturation constraints and parameter uncertainties are adequately considered in the proposed control strategy. At first, the nonlinear dynamic model for control of an ET is described. According to the dynamical model, the nonlinear adaptive sliding-mode tracking control method is presented,where parameter adaptive laws and auxiliary design system are employed. Parameter adaptive law is given to estimate the unknown parameter with an ET. An auxiliary system is designed,and its state is utilized in the tracking control method to handle the input saturation. Stability proof and analysis of the adaptive sliding-mode control method is performed by using Lyapunov stability theory. Finally, the reliability and feasibility of the proposed control strategy are evaluated by computer simulation.Simulation research shows that the proposed sliding-mode control strategy can provide good control performance for an ET.
基金the Ministerial Level Foundation (5040001) the Nationality Excellence Doctor Thesis Foster & Encouragement Foundation of School of MechanicalVehicular Engineering,Beijing Institute of Technology(No 010003)
文摘Based on the solution of the governing differential equation for deformation of throttle slice while satisfying required boundary conditions, the coefficient (Gr) and an analytical formula for computing the deformation of throttle slice is presented through equivalency transformation, which is a concise, accurate and practical method for throttle slice design and characteristic analysis. Researched the deformation at any radius, compared with ANSYS FEA software by the simulation analysis, the availability opening size of throttle that was defined by the deformation at the valve mouth radius is studied. The affection of valve mouth radius to the damper characteristic is analyzed. Tests are made for the damper characteristic, compared with simulation results, it is shown that Gr method is an accurate computation method for computing the deformation of throttle slice at valve mouth radius, suitihle to use in the damper design, analysis, and verification. The deformation at mouth radius could not be replaced with the outside radius.
基金supported by the Ministry of Science and Technology of the People’s Republic of China[grant numbers 2017YFC0211304]the Natural Science Foundation of Shandong Province[grant number ZR2019MEE041]the Open Fund of the National Engineering Laboratory for Mobile Source Emission Control Technology[grant number NELMS2017A14].
文摘In order to effectively implement DPF(Diesel Particulate Filters)regeneration control,thermal management of exhaust products before and inside Diesel Oxidation Catalyst(DOC)is necessary.In the present study,the Influence of the intake throttle valve and late post injection process on temperature rise inside DOC is analyzed through engine bench tests.The steady experiment results show that adjustment of the intake throttle valve can effectively increase exhaust temperature before DOC;in particular,with intake throttle valve opening at 20%,temperature before DOC can be increased by about 170℃ with respect to the full opening.An increase in the late post injection quantity can produce a significant rise of the temperature inside DOC,however its impact on the exhaust temperature before DOC is relatively limited.As the late post injection quantity increases,Hydrocarbon(HC)emissions also grow;in the present work it is shown that with a proper injection quantity,a considerable temperature increase inside the DOC can be obtained with relatively low HC emission.More specifically,with the intake throttle valve at 30%and DOC reaching ignition temperature as the late post injection quantity is increased,the exhaust temperature after DOC can be made larger than 550℃,adequate for DPF active regeneration.
基金This project is supported by National Natural Science Foundation of China (No.50375056, 59975031).
文摘Experimental investigations are made on the effects of operating conditionson the flow characteristics of throttle when tap water is used as the working media. The researchedthrottles include cone poppet valve, ball valve, disc valve and dumping orifice. Operating conditionincludes poppet lift, working media, back pressure, medium temperature, etc. Because the vapourouspressure of water is much higher than that of oil, cavitation is easier to occur in water hydraulicelements and systems, so the effects of operating conditions on the cavitation characteristics ofthrottle are also researched.
基金the National Natural Science Foundation of China (50122155)
文摘A new longitudinal control strategy for vehicle adaptive cruise control (ACC) systems is presented. The running relationship between the ACC vehicle and the detected target vehicle is described by the relative velocity and the deviation between the actual headway distance and the prescribed safety distance. Based on this, two state space models are built and the linear quadratic optimal control theory is used to yield desired velocity for the ACC-equipped vehicle when with the target vehicle detected. By switching among four control modes, the desired velocity profile is designed to deal with different running situations. A velocity controller, which includes a PID controller for throttle openness and a neural network controller for brake application, is developed to achieve the desired velocity profile. The proposed control strategy is applied to a non-linear vehicle model in a simulation environment and is shown to provide the ACC vehicle comfortable ride and satisfying safety.
基金This project is supported by Provincial Open Foundation of Key Lab forAutomobile of Jiangsu, China (No.KJS02076) and 985 Project of AutomotiveEngineering Innovation Platform of Jilin University, China.
文摘Combining with the development of automated manual transmission (AMT), the various throttle control demands are analyzed under different working conditions of AMT such as tracking acceleration pedal, start, shift and so on. Based on simulation, the responding throttle control strategies are proposed, and a simple but effective throttle control method is presented. The testing results have proved that the strategies are effective for improving the pedal tracking precision and the qualities of start and shift.
基金Sponsored by the Ministerial Level Advanced Research Foundation (623010202 4)
文摘In allusion to easy invalidation of damping valve in vehicle shock absorber caused by the impact from the road surface, the importance of the study of damping valve water hammer pressure is presented. The physical model of damping valve with the circle throttle slice is established. The time for the throttle slice deformation is studied by using the finite software, and the laws that how the structure parameters affect the deformation time are obtained. Combining the theory of water hammer, the water hammer initial and boundary condition of the damping valve is deduced, and the water hammer model of throttle slice is established. The analysis of simulation results indicates that the water hammer pressure amplitude and the amount of water hammer oscillation period can be reduced and the dependability of the valve can be enhanced by modifying the structure parameters and aperture width between slice and valve body.