During combined peanut harvesting operations,the separating device plays a crucial role in determining peanuts’damage rate and impurity content.In order to enhance the quality and efficiency of peanut harvesting,this...During combined peanut harvesting operations,the separating device plays a crucial role in determining peanuts’damage rate and impurity content.In order to enhance the quality and efficiency of peanut harvesting,this study investigates the separating device of a two-ridge and four-row half-feeder combine harvester.Firstly,the operating principle of the separating device was analyzed,and a combined air-and-screen separating device was selected.Secondly,based on the movement state of peanut pod impurities in different sections of the separating device surface,the theoretical analysis of peanut pod impurity movement was carried out,and the peanut pod impurity dynamics model was constructed.At the same time,CFD software was used to analyze the airflow field inside the separating device.Moreover,the test factors affecting the separating effect were explored:fan wind speed,separating device surface inclination,and vibration frequency.The optimal working parameters of the device were determined as follows:a fan wind speed of 8.9 m/s,a separating device surface inclination angle of 8.3°concerning the horizontal,and a separating device vibration frequency of 7.2 Hz.The impurity content rate of the peanut pods was 1.48%,and the damage rate of the separating device was 1.61%.Finally,the impurity content of peanuts in the validation experiment was 1.53%,and the peanut damage rate was 1.68%.The effectiveness of the separating device operation was verified through field tests.The potential for further research on peanut harvesters is highlighted based on the findings of this study.展开更多
As a critical component of pulse solid rocket motors(SRMs),the soft pulse separation device(PSD)is vital in enabling multi-pulse propulsion and has become a breakthrough in SRM engineering applications.To investigate ...As a critical component of pulse solid rocket motors(SRMs),the soft pulse separation device(PSD)is vital in enabling multi-pulse propulsion and has become a breakthrough in SRM engineering applications.To investigate the opening performance of the PSD,an axial PSD incorporating a star-shaped prefabricated defect was designed.The opening process was simulated using peridynamics,yielding the strain field distribution and the corresponding failure mode.A single-opening verification test was conducted.The simulation results showed good agreement with the experimental data,demonstrating the reliability of the peridynamic modeling approach.Furthermore,the effects of the prefabricated defect shape and depth on the opening performance of the PSD were analyzed through simulation.The research results indicate that the established constitutive model and failure criteria based on peridynamics can reasonably predict the failure location and the opening pressure of the soft PSD.Under the impact loading,the weak zone of the soft PSD firstly ruptures,and the damaged area gradually propagates along with the prefabricated defect,eventually leading to complete separation.A smaller prefabricated defect depth or a wider prefabricated defect distribution can cause a reduction in opening pressure.These research results provide valuable guidance for the preliminary design and optimization of PSDs in pulse solid rocket motors.展开更多
The safety and reliability of space connection and separation device has become a key issue due to the increasing service span of deep space exploration mission.The long-term preload relaxation(a key failure mode)of c...The safety and reliability of space connection and separation device has become a key issue due to the increasing service span of deep space exploration mission.The long-term preload relaxation(a key failure mode)of connection and separation devices is focused in this paper.A series of tests have been designed and implemented to investigate the preload relaxation regulation and a comprehensive method has been constructed to analyze and predict the reliable lifetime of the device.The two-stage preload relaxation law of the device is found and reasonably considered.Due to the different relaxation mechanism,the first-stage preload relaxation is assessed based on the working-condition test results,and the second-stage preload relaxation is characterized by accelerated test results.Finally,the service reliability and reliable life are evaluated.The experiment and assessment results demonstrate the reasonability and effectiveness of the proposed method which can achieve long-service reliability analysis for space connection and separation device within limited time.展开更多
As a driving element,the spiral torsion spring can control the release velocity by the optimization design of spring parameters and be used for separation devices,which is conducive to unlocking synchronicity and low-...As a driving element,the spiral torsion spring can control the release velocity by the optimization design of spring parameters and be used for separation devices,which is conducive to unlocking synchronicity and low-shock of the separation. On the basis of analyzing the performance requirements of the spiral torsion spring in a spacecraft device,the optimization design model of the spiral torsion spring is given, which takes the spiral torsion spring's length,width and thickness as the optimization variables,and the minimum volume as the optimization objective. The model considers output torque,strength,the maximal resetting load,holding force,and low shock as constraint conditions. A case is given to analyze the proposed model. The analysis results show the optimization scheme decreases the volume of the spiral torsion spring and meets the performance requirements of the separation device.展开更多
Porous polymer beads（PPBs） containing hierarchical bimodal pore structure with gigapores and meso-macropores were prepared by polymerization-induced phase separation（PIPS） and emulsion-template technique in a glas...Porous polymer beads（PPBs） containing hierarchical bimodal pore structure with gigapores and meso-macropores were prepared by polymerization-induced phase separation（PIPS） and emulsion-template technique in a glass capillary microfluidic device（GCMD）. Fabrication procedure involved the preparation of water-in-oil emulsion by emulsifying aqueous solution into the monomer solution that contains porogen. The emulsion was added into the GCMD to fabricate the（water-in-oil）-in-water double emulsion droplets. The flow rate of the carrier continuous phase strongly influenced the formation mechanism and size of droplets. Formation mechanism transformed from dripping to jetting and size of droplets decreased from 550 μm to 250 μm with the increase in flow rate of the carrier continuous phase. The prepared droplets were initiated for polymerization by on-line UV-irradiation to form PPBs. The meso-macropores in these beads were generated by PIPS because of the presence of porogen and gigapores obtained from the emulsion-template. The pore morphology and pore size distribution of the PPBs were investigated extensively by scanning electron microscopy and mercury intrusion porosimetry（MIP）. New pore morphology was formed at the edge of the beads different from traditional theory because of different osmolarities between the water phase of the emulsion and the carrier continuous phase. The morphology and proportion of bimodal pore structure can be tuned by changing the kind and amount of porogen.展开更多
To investigate the influence of design parameters on the performance of separation device,the structure and air-operated test of a low-shock separation device are introduced and analyzed in this paper.According to the...To investigate the influence of design parameters on the performance of separation device,the structure and air-operated test of a low-shock separation device are introduced and analyzed in this paper.According to the law of energy conservation and aerodynamics,a mathematical model is built.Because the preload used to ensure the connection reliability has the discreteness,which will influence the separation process,the influence of preload discreteness on the air-operated separation process is simulated and tested.Simulation results are consistent with the experimental results.It is shown that the change of preload has an obvious influence on the separation process.The study is useful for the design and optimization of separation device.展开更多
Non-pyrotechnic separation devices have been fully recognized for their high performance and high reliability.The focus of this paper is mainly around the development of memory alloy satellite and rocket separation de...Non-pyrotechnic separation devices have been fully recognized for their high performance and high reliability.The focus of this paper is mainly around the development of memory alloy satellite and rocket separation devices.Due to the increasing demand for small-sized rockets and satellites,some suggestions and experiments for developing this new type of non-pyrotechnic device are proposed and conducted.展开更多
This paper describes new methods to reset the secondary valve rob of hydraulic mechanism to its original position due to improper operation and low voltage test after the installation of anti-slow separating device, a...This paper describes new methods to reset the secondary valve rob of hydraulic mechanism to its original position due to improper operation and low voltage test after the installation of anti-slow separating device, and compares the advantages and disadvantages with two previous methods to return the secondary valve rob to the opening position.展开更多
Onboard air separation devices,based on hollow fiber membranes,are traditionally used for the optimization of aircraft fuel tank inerting systems.In the present study,a set of tests have been designed and executed to ...Onboard air separation devices,based on hollow fiber membranes,are traditionally used for the optimization of aircraft fuel tank inerting systems.In the present study,a set of tests have been designed and executed to assess the air separation performances of these systems for different air inlet temperatures(70°C∼110°C),inlet pressures(0.1∼0.4 MPa),volume flow rates of nitrogen-enriched air(NEA)(30∼120 L/min)and flight altitudes(1.5∼18 km).In particular,the temperature,pressure,volume flow rate,and oxygen concentration of air,NEA and oxygen-enriched air(OEA)have been measured.The experimental results show that the oxygen concentration of NEA,air separation coefficient,and nitrogen utilization coefficient decrease with the rising of air inlet temperature,air inlet pressure,and flight altitude.The effect of air inlet pressure on the above three parameters is significant,while the influence of air inlet temperature and flight altitude is relatively small.展开更多
In this paper,two new concepts—“main out-of-step mode” and “minor out-of-step mode”—are proposed for power system reliability analysis. Large-scale power system studies found that out-of-step generator groups ma...In this paper,two new concepts—“main out-of-step mode” and “minor out-of-step mode”—are proposed for power system reliability analysis. Large-scale power system studies found that out-of-step generator groups may have characteristics of the main out-of-step mode and the minor out-of-step mode. The generator groups with main out-of-step modes can determine the out-of-step interface of the large-scale power system,while generators with the minor out-of-step modes cannot play such a role. Therefore,the method of capturing the out-of-step interface by seeking the lowest voltage point(the out-of-step center) can only group the generators with the main out-of-step modes,and may fail to combine the generators with the minor out-of-step modes into proper coherent generator groups. Thus,it is necessary in engineering applications to equip the generators that are likely to have the characteristics of the minor out-of-step modes with separation devices based on off-line simulation studies in order to reduce the risk of further accidents caused by these generators after system separation.展开更多
We study the extended gate ion sensitive structure,and deposit the titanium oxide (TiO_2) thin film on p-type (100) silicon substrate.The device of the hydrogen ion sensing structure is TiO_2/Si-substrate,and a commer...We study the extended gate ion sensitive structure,and deposit the titanium oxide (TiO_2) thin film on p-type (100) silicon substrate.The device of the hydrogen ion sensing structure is TiO_2/Si-substrate,and a commercial device of the metal oxide semiconductor field effect transistor (MOSFET) is connected to the separative sensing device.The sensitivity and linearity are measured under different work pressures.When the mixed ratio of Ar/O_2 is 80 ml·min^(-1)/20 ml·min^(-1),the work pressure is 4 Pa,the sputtering power is 150 W,and the sputtering time is two hours,the better sensing properties of the sensitivity and linearity are 36.49 mV/pH and 0.99654,respectively.However,some instruments are analyzed the surface of TiO_2 membrane,such as X-ray diffraction (XRD) and Auger Electron Spectrometer (AES).The characteristics of TiO_2 thin film can be demonstrated.展开更多
In order to further clarify and improve the working performance of separating cleaning device of flax threshing material,and study the motion law and characteristics of components of flax threshing material,in this pa...In order to further clarify and improve the working performance of separating cleaning device of flax threshing material,and study the motion law and characteristics of components of flax threshing material,in this paper,numerical simulation was carried out on the separating cleaning process of flax threshing material based on CFD-DEM method.Simulation results showed that the components of flax threshing material were separated and cleaned under the influence of airflow field,meanwhile,variation curves of quantity and mean velocity of flax seeds in the separating cleaning system were obtained.By referring to streamline distribution of gas-solid coupling,the quantity variation law of components of flax threshing material with time was explored and their motion curves and variation tendency of average velocity were studied.Verification test results showed that the cleaning rate of separating cleaning device for flax threshing material was 92.66%with 1.58%of total separation loss.Compared with simulation results,the test results were 1.34%and 0.93%lower,showing that it is feasible to apply the gas-solid coupling theory and method to simulate the separating and cleaning operation of flax threshing material.展开更多
This article deals with the characteristics of weakly swirling turbulent flow field in a Turbid Water Hydraulic Separation Device （TWHSD） through experimental and numerical researches. The flow field was measured by...This article deals with the characteristics of weakly swirling turbulent flow field in a Turbid Water Hydraulic Separation Device （TWHSD） through experimental and numerical researches. The flow field was measured by PIV, which provided streamlines, vortex structure, vorticity and velocity distribution in different test planes in the TWHSD. On the basis of the experimental results, the tangential and radial velocity distributions of the swirling flow field were obtained. Meanwhile, the numerical simulations were conducted with the RNG κ-ε and RSM turbulence models, respectively. According to the experimental and numerical results, the characteristics of the clear water flow field inside the TWHSD were determined. In view of simulation accuracy and time consumption, it is suggested to apply the RNG κ-ε model instead of the RSM model, which is more time consuming, to make further study on two-phases flow fields in the device.展开更多
Multi-gradient drilling is a new offshore drilling method.The accurate calculation of the related wellbore temperature is of great significance for the prediction of the gas hydrate formation area and the precise cont...Multi-gradient drilling is a new offshore drilling method.The accurate calculation of the related wellbore temperature is of great significance for the prediction of the gas hydrate formation area and the precise control of the wellbore pressure.In this study,a new heat transfer model is proposed by which the variable mass flow is properly taken into account.Using this model,the effects of the main factors influencing the wellbore temperature are analyzed.The results indicate that at the position where the separation injection device is installed,the temperature increase of the fluid in the drill pipe is mitigated due to the inflow/outflow of hollow spheres,and the temperature drop of the fluid in the annulus also decreases.In addition,a lower separation efficiency of the device,a shallower installation depth and a smaller circulating displacement tend to increase the temperature near the bottom of the annulus,thereby helping to reduce the hydrate generation area and playing a positive role in the prevention and control of hydrates in deepwater drilling.展开更多
Molecularly imprinted polymers are generated by curing a cross-linked polymer in the presence of a template. During the curing process, noncovalent bonds form between the polymer and the template. The interaction site...Molecularly imprinted polymers are generated by curing a cross-linked polymer in the presence of a template. During the curing process, noncovalent bonds form between the polymer and the template. The interaction sites for the noncovalent bonds become "frozen" in the cross-linking polymer and maintain their shape even after the template is removed. The resulting cavities reproduce the size and shape of the template and can selectively reincorporate the template when a mixture containing it flows over the imprinted surface. In the last few decades the field of molecular imprinting has evolved from being able to selectively capture only small molecules to dealing with all kinds of samples. Molecularly imprinted polymers (MIPs) have been generated for analytes as diverse as metal ions, drug molecules, environmental pollutants, proteins and viruses to entire cells. We review here the relatively new field of surface imprinting, which creates imprints of large, biologically relevant templates. The traditional bulk imprinting, where a template is simply added to a prepolymer before curing, cannot be applied if the analyte is too large to diffuse from the cured polymer. Special methods must be used to generate binding sites only on a surface. Those techniques have solved crucial problems in separation science as well as chemical and biochemical sensing. The implementation of imprinted polymers into microfluidic chips has greatly improved the applicability of microfluidics. We present the latest advances and different approaches of surface imprinting and their applications for microfluidic devices.展开更多
Walnut shell-kernel separation after cracking is crucial for providing raw materials for further processing.However,impurities and losses during separation limit complete separation.To address this,a two-stage tandem ...Walnut shell-kernel separation after cracking is crucial for providing raw materials for further processing.However,impurities and losses during separation limit complete separation.To address this,a two-stage tandem separation device was designed and optimized.Computational fluid dynamics(CFD)was used to analyze the effects of four bent duct structures on the flow field.Response surface methodology(RSM)and artificial neural networks(ANN)were employed to predict separation performance under various conditions.Both models accurately predicted performance,with ANN showing superior predictive ability.The optimal design was determined using non-dominated sorting genetic algorithm-II(NSGA-II)and technique for order preference by similarity to an ideal solution(TOPSIS):the inclination of the first stage deflector plate(x1)was 39°,the inclination of the second stage deflector plate(x2)was 36°,the wind speed of the first stage fan(x3)was 21 m/s,and the wind speed of the second stage fan(x4)was 13.5 m/s;impurity rate(y1)was 4.51%,and loss rate(y2)was 6.62%.Compared with traditional single-stage devices,the optimized device reduced impurity rate by 73.98%to 77.55%and loss rate by 9.44%to 53.96%,significantly improving separation efficiency and quality.This study provides theoretical guidance for designing and optimizing shell-kernel separation devices.展开更多
In order to solve the problems of unclear film separation in traditional topsoil residual film recovery machine and secondary broken film caused by the toot-shaped structure,a film-soil conveying and vibration separat...In order to solve the problems of unclear film separation in traditional topsoil residual film recovery machine and secondary broken film caused by the toot-shaped structure,a film-soil conveying and vibration separation device was designed.It mainly consists of a first-level vibration conveying chain,roller extrusion and crushing mechanism and secondary conveyor chain,which can complete the functions of conveying,vibration separation,and crushing separation of film-soil composite.Firstly,the mechanical model of the transport process of the film-soil composite was established,and the transport stability of the film-soil composite was analyzed.The vibration characteristics of the vibration mechanism were analyzed by analytical method,and the vibration model of the vibration mechanism was established.The distribution state of residual film-soil mixture was observed and measured by high-speed camera,and the influence of vibration wheel speed and installation distance on the distribution height of residual film-soil mixture was found out.The crushing mechanism of the residual film-soil composite was proved by studying the roller extrusion and crushing mechanism.The Box-Behnken response surface test method was used to carry out field tests on the transport and vibration separation device of film-soil with soil content rate and film leakage rate as evaluation indices.The results indicated that the influencing factors on the soil content rate in a dscending order are conveyor chain speed,vibration wheel speed,and installation distance.In contrast,the factors affecting the film leakage rate,also ranked from largest to smallest,are conveyor chain speed,installation distance,and vibration wheel speed.The combination of film-soil separation parameters is as follows:conveying chain speed is 1.6 km/h,vibration wheel speed is 189.7 r/min,installation distance is 769.7 mm,at this time the soil content rate is 18.31%,and the film leakage rate is 9.49%,which meet the requirements of the recovery of residual film in the plough layer.The conveying and vibration model established in this study can provide a theoretical basis and technical reference for elucidating the soil-film separation process.展开更多
基金financially sponsored by the Key R&D Program(Major Science and Technology Innovation Project)in Shandong Province(Grant No.2021CXGC010813)the National Key Research and Development Program(Grant No.2022YFD2300100).
文摘During combined peanut harvesting operations,the separating device plays a crucial role in determining peanuts’damage rate and impurity content.In order to enhance the quality and efficiency of peanut harvesting,this study investigates the separating device of a two-ridge and four-row half-feeder combine harvester.Firstly,the operating principle of the separating device was analyzed,and a combined air-and-screen separating device was selected.Secondly,based on the movement state of peanut pod impurities in different sections of the separating device surface,the theoretical analysis of peanut pod impurity movement was carried out,and the peanut pod impurity dynamics model was constructed.At the same time,CFD software was used to analyze the airflow field inside the separating device.Moreover,the test factors affecting the separating effect were explored:fan wind speed,separating device surface inclination,and vibration frequency.The optimal working parameters of the device were determined as follows:a fan wind speed of 8.9 m/s,a separating device surface inclination angle of 8.3°concerning the horizontal,and a separating device vibration frequency of 7.2 Hz.The impurity content rate of the peanut pods was 1.48%,and the damage rate of the separating device was 1.61%.Finally,the impurity content of peanuts in the validation experiment was 1.53%,and the peanut damage rate was 1.68%.The effectiveness of the separating device operation was verified through field tests.The potential for further research on peanut harvesters is highlighted based on the findings of this study.
基金supported by the National Natural Science Foundation of China(No.12202011)the Youth Research fund of Shanghai Academy of Spaceflight Technology(KJW-KT-QNKYJJ-2022-25)China Postdoctoral Science Foundation(Nos.2024T170009,2022M710190).
文摘As a critical component of pulse solid rocket motors(SRMs),the soft pulse separation device(PSD)is vital in enabling multi-pulse propulsion and has become a breakthrough in SRM engineering applications.To investigate the opening performance of the PSD,an axial PSD incorporating a star-shaped prefabricated defect was designed.The opening process was simulated using peridynamics,yielding the strain field distribution and the corresponding failure mode.A single-opening verification test was conducted.The simulation results showed good agreement with the experimental data,demonstrating the reliability of the peridynamic modeling approach.Furthermore,the effects of the prefabricated defect shape and depth on the opening performance of the PSD were analyzed through simulation.The research results indicate that the established constitutive model and failure criteria based on peridynamics can reasonably predict the failure location and the opening pressure of the soft PSD.Under the impact loading,the weak zone of the soft PSD firstly ruptures,and the damaged area gradually propagates along with the prefabricated defect,eventually leading to complete separation.A smaller prefabricated defect depth or a wider prefabricated defect distribution can cause a reduction in opening pressure.These research results provide valuable guidance for the preliminary design and optimization of PSDs in pulse solid rocket motors.
基金supported by the National Natural Science Foundation of China(No.11872085)。
文摘The safety and reliability of space connection and separation device has become a key issue due to the increasing service span of deep space exploration mission.The long-term preload relaxation(a key failure mode)of connection and separation devices is focused in this paper.A series of tests have been designed and implemented to investigate the preload relaxation regulation and a comprehensive method has been constructed to analyze and predict the reliable lifetime of the device.The two-stage preload relaxation law of the device is found and reasonably considered.Due to the different relaxation mechanism,the first-stage preload relaxation is assessed based on the working-condition test results,and the second-stage preload relaxation is characterized by accelerated test results.Finally,the service reliability and reliable life are evaluated.The experiment and assessment results demonstrate the reasonability and effectiveness of the proposed method which can achieve long-service reliability analysis for space connection and separation device within limited time.
基金Natural Science Foundation of Liaoning Province,China(No.2015020121)Research Fund for the Doctoral Program of Higher Education of China(No.20122125120013)the Fundamental Research Funds for the Central Universities,China(Nos.3132015087,3132014303)
文摘As a driving element,the spiral torsion spring can control the release velocity by the optimization design of spring parameters and be used for separation devices,which is conducive to unlocking synchronicity and low-shock of the separation. On the basis of analyzing the performance requirements of the spiral torsion spring in a spacecraft device,the optimization design model of the spiral torsion spring is given, which takes the spiral torsion spring's length,width and thickness as the optimization variables,and the minimum volume as the optimization objective. The model considers output torque,strength,the maximal resetting load,holding force,and low shock as constraint conditions. A case is given to analyze the proposed model. The analysis results show the optimization scheme decreases the volume of the spiral torsion spring and meets the performance requirements of the separation device.
文摘Porous polymer beads（PPBs） containing hierarchical bimodal pore structure with gigapores and meso-macropores were prepared by polymerization-induced phase separation（PIPS） and emulsion-template technique in a glass capillary microfluidic device（GCMD）. Fabrication procedure involved the preparation of water-in-oil emulsion by emulsifying aqueous solution into the monomer solution that contains porogen. The emulsion was added into the GCMD to fabricate the（water-in-oil）-in-water double emulsion droplets. The flow rate of the carrier continuous phase strongly influenced the formation mechanism and size of droplets. Formation mechanism transformed from dripping to jetting and size of droplets decreased from 550 μm to 250 μm with the increase in flow rate of the carrier continuous phase. The prepared droplets were initiated for polymerization by on-line UV-irradiation to form PPBs. The meso-macropores in these beads were generated by PIPS because of the presence of porogen and gigapores obtained from the emulsion-template. The pore morphology and pore size distribution of the PPBs were investigated extensively by scanning electron microscopy and mercury intrusion porosimetry（MIP）. New pore morphology was formed at the edge of the beads different from traditional theory because of different osmolarities between the water phase of the emulsion and the carrier continuous phase. The morphology and proportion of bimodal pore structure can be tuned by changing the kind and amount of porogen.
文摘To investigate the influence of design parameters on the performance of separation device,the structure and air-operated test of a low-shock separation device are introduced and analyzed in this paper.According to the law of energy conservation and aerodynamics,a mathematical model is built.Because the preload used to ensure the connection reliability has the discreteness,which will influence the separation process,the influence of preload discreteness on the air-operated separation process is simulated and tested.Simulation results are consistent with the experimental results.It is shown that the change of preload has an obvious influence on the separation process.The study is useful for the design and optimization of separation device.
文摘Non-pyrotechnic separation devices have been fully recognized for their high performance and high reliability.The focus of this paper is mainly around the development of memory alloy satellite and rocket separation devices.Due to the increasing demand for small-sized rockets and satellites,some suggestions and experiments for developing this new type of non-pyrotechnic device are proposed and conducted.
文摘This paper describes new methods to reset the secondary valve rob of hydraulic mechanism to its original position due to improper operation and low voltage test after the installation of anti-slow separating device, and compares the advantages and disadvantages with two previous methods to return the secondary valve rob to the opening position.
基金This project is supported by the Fund of Natural Science Project of Hunan Province,China,with the Item No.2020JJ5393Education Department of Hunan Province,China,with the Item No.18C0735.
文摘Onboard air separation devices,based on hollow fiber membranes,are traditionally used for the optimization of aircraft fuel tank inerting systems.In the present study,a set of tests have been designed and executed to assess the air separation performances of these systems for different air inlet temperatures(70°C∼110°C),inlet pressures(0.1∼0.4 MPa),volume flow rates of nitrogen-enriched air(NEA)(30∼120 L/min)and flight altitudes(1.5∼18 km).In particular,the temperature,pressure,volume flow rate,and oxygen concentration of air,NEA and oxygen-enriched air(OEA)have been measured.The experimental results show that the oxygen concentration of NEA,air separation coefficient,and nitrogen utilization coefficient decrease with the rising of air inlet temperature,air inlet pressure,and flight altitude.The effect of air inlet pressure on the above three parameters is significant,while the influence of air inlet temperature and flight altitude is relatively small.
基金Project (No. 50277034) supported by the National Natural ScienceFoundation of China
文摘In this paper,two new concepts—“main out-of-step mode” and “minor out-of-step mode”—are proposed for power system reliability analysis. Large-scale power system studies found that out-of-step generator groups may have characteristics of the main out-of-step mode and the minor out-of-step mode. The generator groups with main out-of-step modes can determine the out-of-step interface of the large-scale power system,while generators with the minor out-of-step modes cannot play such a role. Therefore,the method of capturing the out-of-step interface by seeking the lowest voltage point(the out-of-step center) can only group the generators with the main out-of-step modes,and may fail to combine the generators with the minor out-of-step modes into proper coherent generator groups. Thus,it is necessary in engineering applications to equip the generators that are likely to have the characteristics of the minor out-of-step modes with separation devices based on off-line simulation studies in order to reduce the risk of further accidents caused by these generators after system separation.
文摘We study the extended gate ion sensitive structure,and deposit the titanium oxide (TiO_2) thin film on p-type (100) silicon substrate.The device of the hydrogen ion sensing structure is TiO_2/Si-substrate,and a commercial device of the metal oxide semiconductor field effect transistor (MOSFET) is connected to the separative sensing device.The sensitivity and linearity are measured under different work pressures.When the mixed ratio of Ar/O_2 is 80 ml·min^(-1)/20 ml·min^(-1),the work pressure is 4 Pa,the sputtering power is 150 W,and the sputtering time is two hours,the better sensing properties of the sensitivity and linearity are 36.49 mV/pH and 0.99654,respectively.However,some instruments are analyzed the surface of TiO_2 membrane,such as X-ray diffraction (XRD) and Auger Electron Spectrometer (AES).The characteristics of TiO_2 thin film can be demonstrated.
基金The authors acknowledge that this work was financially supported by China Agriculture Research System(CARS-14-1-28)Discipline construction fund project of Gansu Agricultural University(GAU-XKJS-2018-189).
文摘In order to further clarify and improve the working performance of separating cleaning device of flax threshing material,and study the motion law and characteristics of components of flax threshing material,in this paper,numerical simulation was carried out on the separating cleaning process of flax threshing material based on CFD-DEM method.Simulation results showed that the components of flax threshing material were separated and cleaned under the influence of airflow field,meanwhile,variation curves of quantity and mean velocity of flax seeds in the separating cleaning system were obtained.By referring to streamline distribution of gas-solid coupling,the quantity variation law of components of flax threshing material with time was explored and their motion curves and variation tendency of average velocity were studied.Verification test results showed that the cleaning rate of separating cleaning device for flax threshing material was 92.66%with 1.58%of total separation loss.Compared with simulation results,the test results were 1.34%and 0.93%lower,showing that it is feasible to apply the gas-solid coupling theory and method to simulate the separating and cleaning operation of flax threshing material.
基金the National Natural Science Foundation of China (Grant No. 50469003)the University Science and Research Key Project of Xinjiang Uygur Autonomous Region(XJEDU 2004121)
文摘This article deals with the characteristics of weakly swirling turbulent flow field in a Turbid Water Hydraulic Separation Device （TWHSD） through experimental and numerical researches. The flow field was measured by PIV, which provided streamlines, vortex structure, vorticity and velocity distribution in different test planes in the TWHSD. On the basis of the experimental results, the tangential and radial velocity distributions of the swirling flow field were obtained. Meanwhile, the numerical simulations were conducted with the RNG κ-ε and RSM turbulence models, respectively. According to the experimental and numerical results, the characteristics of the clear water flow field inside the TWHSD were determined. In view of simulation accuracy and time consumption, it is suggested to apply the RNG κ-ε model instead of the RSM model, which is more time consuming, to make further study on two-phases flow fields in the device.
基金funded by the Key Program of National Natural Science Foundation of China(Grant No.51734010)the Startup Fund of Changzhou University Science Research(Grant No.ZMF22020060).
文摘Multi-gradient drilling is a new offshore drilling method.The accurate calculation of the related wellbore temperature is of great significance for the prediction of the gas hydrate formation area and the precise control of the wellbore pressure.In this study,a new heat transfer model is proposed by which the variable mass flow is properly taken into account.Using this model,the effects of the main factors influencing the wellbore temperature are analyzed.The results indicate that at the position where the separation injection device is installed,the temperature increase of the fluid in the drill pipe is mitigated due to the inflow/outflow of hollow spheres,and the temperature drop of the fluid in the annulus also decreases.In addition,a lower separation efficiency of the device,a shallower installation depth and a smaller circulating displacement tend to increase the temperature near the bottom of the annulus,thereby helping to reduce the hydrate generation area and playing a positive role in the prevention and control of hydrates in deepwater drilling.
文摘Molecularly imprinted polymers are generated by curing a cross-linked polymer in the presence of a template. During the curing process, noncovalent bonds form between the polymer and the template. The interaction sites for the noncovalent bonds become "frozen" in the cross-linking polymer and maintain their shape even after the template is removed. The resulting cavities reproduce the size and shape of the template and can selectively reincorporate the template when a mixture containing it flows over the imprinted surface. In the last few decades the field of molecular imprinting has evolved from being able to selectively capture only small molecules to dealing with all kinds of samples. Molecularly imprinted polymers (MIPs) have been generated for analytes as diverse as metal ions, drug molecules, environmental pollutants, proteins and viruses to entire cells. We review here the relatively new field of surface imprinting, which creates imprints of large, biologically relevant templates. The traditional bulk imprinting, where a template is simply added to a prepolymer before curing, cannot be applied if the analyte is too large to diffuse from the cured polymer. Special methods must be used to generate binding sites only on a surface. Those techniques have solved crucial problems in separation science as well as chemical and biochemical sensing. The implementation of imprinted polymers into microfluidic chips has greatly improved the applicability of microfluidics. We present the latest advances and different approaches of surface imprinting and their applications for microfluidic devices.
文摘Walnut shell-kernel separation after cracking is crucial for providing raw materials for further processing.However,impurities and losses during separation limit complete separation.To address this,a two-stage tandem separation device was designed and optimized.Computational fluid dynamics(CFD)was used to analyze the effects of four bent duct structures on the flow field.Response surface methodology(RSM)and artificial neural networks(ANN)were employed to predict separation performance under various conditions.Both models accurately predicted performance,with ANN showing superior predictive ability.The optimal design was determined using non-dominated sorting genetic algorithm-II(NSGA-II)and technique for order preference by similarity to an ideal solution(TOPSIS):the inclination of the first stage deflector plate(x1)was 39°,the inclination of the second stage deflector plate(x2)was 36°,the wind speed of the first stage fan(x3)was 21 m/s,and the wind speed of the second stage fan(x4)was 13.5 m/s;impurity rate(y1)was 4.51%,and loss rate(y2)was 6.62%.Compared with traditional single-stage devices,the optimized device reduced impurity rate by 73.98%to 77.55%and loss rate by 9.44%to 53.96%,significantly improving separation efficiency and quality.This study provides theoretical guidance for designing and optimizing shell-kernel separation devices.
基金supported by the Science and Technology Innovation Leading Talent Project(Grant No.2024TSYCLJ0014)the Xinjiang Agricultural Machinery R&D Manufacturing Promotion and Autonomous Region Graduate Research Innovation Project(Grant No.XJ2024G103)the Xinjiang Uygur Autonomous Region“Unveiling and Leading”Project“High-Quality and High-Efficiency Mechanized Recovery Technology R&D and Equipment Application for Farmland Plastic Film Residue”,and the Xinjiang Uygur Autonomous Region“Unveiling and Leading”Project(Grant No.XJJBGS-MG202403).
文摘In order to solve the problems of unclear film separation in traditional topsoil residual film recovery machine and secondary broken film caused by the toot-shaped structure,a film-soil conveying and vibration separation device was designed.It mainly consists of a first-level vibration conveying chain,roller extrusion and crushing mechanism and secondary conveyor chain,which can complete the functions of conveying,vibration separation,and crushing separation of film-soil composite.Firstly,the mechanical model of the transport process of the film-soil composite was established,and the transport stability of the film-soil composite was analyzed.The vibration characteristics of the vibration mechanism were analyzed by analytical method,and the vibration model of the vibration mechanism was established.The distribution state of residual film-soil mixture was observed and measured by high-speed camera,and the influence of vibration wheel speed and installation distance on the distribution height of residual film-soil mixture was found out.The crushing mechanism of the residual film-soil composite was proved by studying the roller extrusion and crushing mechanism.The Box-Behnken response surface test method was used to carry out field tests on the transport and vibration separation device of film-soil with soil content rate and film leakage rate as evaluation indices.The results indicated that the influencing factors on the soil content rate in a dscending order are conveyor chain speed,vibration wheel speed,and installation distance.In contrast,the factors affecting the film leakage rate,also ranked from largest to smallest,are conveyor chain speed,installation distance,and vibration wheel speed.The combination of film-soil separation parameters is as follows:conveying chain speed is 1.6 km/h,vibration wheel speed is 189.7 r/min,installation distance is 769.7 mm,at this time the soil content rate is 18.31%,and the film leakage rate is 9.49%,which meet the requirements of the recovery of residual film in the plough layer.The conveying and vibration model established in this study can provide a theoretical basis and technical reference for elucidating the soil-film separation process.
