To achieve the secondary production in multistage fracturing wells of tight oil,milling tools are usually used to remove the multistage fracturing ball seats to achieve production with a large diameter in later.In thi...To achieve the secondary production in multistage fracturing wells of tight oil,milling tools are usually used to remove the multistage fracturing ball seats to achieve production with a large diameter in later.In this paper,first of all,the working mechanism of milling tools for multistage fracturing ball seats was studied and a mechanical analysis model of single abrasive grain was established.Then,an experimental system for milling tools was developed,and the experimental tests of the flat,the blade,and the slope milling tool were conducted in order.Besides,the morphology of chips and the surface morphology of the workpiece after the experiment were analyzed.Also,the working performance of milling tools was evaluated from the perspectives of working safety,working efficiency,and wear resistance of the milling tool.The results show that the torque of the milling tool increases nonlinearly with the increase in the cutting depth of the abrasive grain and increases linearly with the increase in the cutting width.Also,the chips are irregular particles and the size is mainly from 10 to 50μm.So,the chips should be pumped up with a small pump pressure and a large displacement.Besides this,the cutting depths of the abrasive grains are from 216.20 to 635.47μm and the bottom surface of the milling tool should be eccentric to avoid the zero point of cutting speed.Furthermore,the torque of the slope milling tool is 23.8%larger than that of the flat milling tool,which is also 30.4%smaller than that of the blade milling tool.Compared with the flat milling tool,the working efficiency of the blade milling tool improves by 79.9%and the slope milling tool improves by 111.1%.Also,the wear resistance of the blade milling tool decreases by 102.7%,while the slope milling tool declines by 32.6%when compared with the flat milling tool.Therefore,the slope milling tool has the characteristics of moderate torque,stable working conditions,the highest working efficiency,and fine wear resistance,which is preferably used to mill multistage fracturing ball seats.This study provides a theoretical basis and guidance for milling multistage fracturing ball seats on-site and realizing production with a large diameter in later stages of multistage fracturing wells.展开更多
Thermal energy storage has been a pivotal technology to fill the gap between energy demands and energy supplies.As a solid-solid phase change material,shape-memory alloys(SMAs)have the inherent advantages of leakage f...Thermal energy storage has been a pivotal technology to fill the gap between energy demands and energy supplies.As a solid-solid phase change material,shape-memory alloys(SMAs)have the inherent advantages of leakage free,no encapsulation,negligible volume variation,as well as superior energy storage properties such as high thermal conductivity(compared with ice and paraffin)and volumetric energy density,making them excellent thermal energy storage materials.Considering these characteristics,the design of the shape-memory alloy based the cold thermal energy storage system for precooling car seat application is introduced in this paper based on the proposed shape-memory alloy-based cold thermal energy storage cycle.The simulation results show that the minimum temperature of the metal boss under the seat reaches 26.2°C at 9.85 s,which is reduced by 9.8°C,and the energy storage efficiency of the device is 66%.The influence of initial temperature,elastocaloric materials,and the shape-memory alloy geometry scheme on the performance of car seat cold thermal energy storage devices is also discussed.Since SMAs are both solid-state refrigerants and thermal energy storage materials,hopefully the proposed concept can promote the development of more promising shape-memory alloy-based cold and hot thermal energy storage devices.展开更多
A system for fully automatic selection of welding specifications in resistance welding equipment has been developed to address the problem of workers frequently choosing the wrong specifications during manual welding ...A system for fully automatic selection of welding specifications in resistance welding equipment has been developed to address the problem of workers frequently choosing the wrong specifications during manual welding of multiple parts on a single machine in automobile factories. The system incorporates an automatic recognition system for different workpiece materials using the added machine fixture,visual detection system for nuts and bolts,and secondary graphical confirmation to ensure the correctness of specification calling. This system achieves reliable,fully automatic selection of welding specifications in resistance welding equipment and has shown significant effects in improving welding quality for massproduced workpieces,while solving the problem of specification calling errors that can occur with traditional methods involving process charts and code adjustments. This system is particularly suitable for promoting applications in manual welding of multiple parts on a single machine in automobile factories,ensuring correct specification calling and welding quality.展开更多
Noise-reduction seats have been successfully used in concert halls, theaters, and other places that reduce noise. In this study, a new noise-reduction seat design was proposed for high-speed trains, which have unique ...Noise-reduction seats have been successfully used in concert halls, theaters, and other places that reduce noise. In this study, a new noise-reduction seat design was proposed for high-speed trains, which have unique interior noise spectral characteristics. First, before the noisereduction seat models were fabricated, the parameters of high-performance sound-absorbing materials and perforated plates were selected by conducting a standing-wave tube test. The sound-absorption effects of the noisereduction seats and normal seats were investigated and compared in a reverberation chamber. Test results showed that, compared with normal seats, the noise-reduction seats obtained a significantly improved sound-absorption coefficient in the entire frequency band. Furthermore, the test results were used to establish a simulation model for calculation, and the simulation results proved that the noise-reduction seats substantially reduced the noise in an entire train car. Finally, the noise-reduction seats were fabricated and installed in a full train car of an actual highspeed train. The test results showed that, compared with the normal seats, the noise-reduction seats decreased the noise level at a standard point in the passenger car by 1.5 dB. Therefore, the noise-reduction seats are effective in noise reduction.展开更多
Hainan Province has revised its villager committee election methods and procedures to ensure women’s participation in local government wang Saixiao was happy about being reelected as the village head. For six years, ...Hainan Province has revised its villager committee election methods and procedures to ensure women’s participation in local government wang Saixiao was happy about being reelected as the village head. For six years, Wang, 34, has served as the head of Baotang Village, Lin’gao County of south China’s Hainan Province.展开更多
The sleeve sealing ball seat is one of the important components in the multistage fracturing process of horizontal wells.The erosion and wear of the surface will decrease the sealing performance of the fracturing ball...The sleeve sealing ball seat is one of the important components in the multistage fracturing process of horizontal wells.The erosion and wear of the surface will decrease the sealing performance of the fracturing ball and the ball seat.This leads to pressure leakage during the fracturing process and fracturing failure.In this paper,combined with the actual ball seat materials and working conditions during the fracturing process,the erosion tests of ductile iron and tungsten carbide materials under different erosion speeds,angles,and mortar concentrations are carried out.Then the erosion test results were analyzed by mathematical fitting,and a set of erosion models suitable for sliding sleeve setting ball seat materials were innovatively established.For the first time,this paper combines the erosion model obtained from the experiment and the computational fluid dynamics(CFD)with Fluent software to simulate the erosion of the ball seat.Based on the simulation results,the morphology of the sliding sleeve seat ball after erosion is predicted.Through analysis of the test and simulation results,it is showed that the erosion rate of tungsten carbide material is lower and the wear resistance is better under the condition of small angle erosion.This research can offer a strong basis for fracturing site selection,surface treatment methods,and prediction of failure time of ball seats.展开更多
Seasonal adjustment has been widely used in statistic analyses.Nowadays,the research on seasonal adjustment methods mainly concentrates on X-11,X-12 etc in China,lacking the whole understanding of foreign seasonal adj...Seasonal adjustment has been widely used in statistic analyses.Nowadays,the research on seasonal adjustment methods mainly concentrates on X-11,X-12 etc in China,lacking the whole understanding of foreign seasonal adjustment methods,and the latest progress of seasonal adjustment methods has been less introduced.In this article,various seasonal adjustment methods were introduced,and a comparison of their characteristics and applications was made.It is helpful that statistical organizations can develop appropriate seasonal adjustment methods,concerning different kinds of data.展开更多
Nowadays days,the chief grounds of automobile accidents are driver fatigue and distractions.With the development of computer vision technology,a cutting-edge system has the potential to spot driver distractions or sle...Nowadays days,the chief grounds of automobile accidents are driver fatigue and distractions.With the development of computer vision technology,a cutting-edge system has the potential to spot driver distractions or sleepiness and alert them,reducing accidents.This paper presents a novel approach to detecting driver tiredness based on eye and mouth movements and object identification that causes a distraction while operating a motor vehicle.Employing the facial landmarks that the camera picks up and sends to classify using a Convolutional Neural Network(CNN)any changes by focusing on the eyes and mouth zone,precision is achieved.One of the tasks that must be performed in the transit system is seat belt detection to lessen accidents caused by sudden stops or high-speed collisions with other cars.A method is put forth to use convolution neural networks to determine whether the motorist is wearing a seat belt when a driver is sleepy,preoccupied,or not wearing their seat belt,this system alerts them with an alarm,and if they don’t wake up by a predetermined time of 3 s threshold,an automatic message is sent to law enforcement agencies.The suggested CNN-based model exhibits greater accuracy with 97%.It can be utilized to develop a system that detects driver attention or sleeps in real-time.展开更多
The purpose of this paper is to present the rationale for registration of the Seated Condylar Position (SCP)/Centric Relation (CR) position of the condyles.
基金supported by the National Science and Technology Major Project under Grant Nos.2016ZX05042004 and 2017ZX05072the Joint Funds of the National Natural Science Foundation of China under Grant No.U1762104+2 种基金the Postgraduate Innovation Project Foundation under Grant No.YCX2019054the Fundamental Research Funds for the Central Universities under Grant No.20CX02306Athe Opening Fund of National Engineering Laboratory of Offshore Geophysical and Exploration Equipment。
文摘To achieve the secondary production in multistage fracturing wells of tight oil,milling tools are usually used to remove the multistage fracturing ball seats to achieve production with a large diameter in later.In this paper,first of all,the working mechanism of milling tools for multistage fracturing ball seats was studied and a mechanical analysis model of single abrasive grain was established.Then,an experimental system for milling tools was developed,and the experimental tests of the flat,the blade,and the slope milling tool were conducted in order.Besides,the morphology of chips and the surface morphology of the workpiece after the experiment were analyzed.Also,the working performance of milling tools was evaluated from the perspectives of working safety,working efficiency,and wear resistance of the milling tool.The results show that the torque of the milling tool increases nonlinearly with the increase in the cutting depth of the abrasive grain and increases linearly with the increase in the cutting width.Also,the chips are irregular particles and the size is mainly from 10 to 50μm.So,the chips should be pumped up with a small pump pressure and a large displacement.Besides this,the cutting depths of the abrasive grains are from 216.20 to 635.47μm and the bottom surface of the milling tool should be eccentric to avoid the zero point of cutting speed.Furthermore,the torque of the slope milling tool is 23.8%larger than that of the flat milling tool,which is also 30.4%smaller than that of the blade milling tool.Compared with the flat milling tool,the working efficiency of the blade milling tool improves by 79.9%and the slope milling tool improves by 111.1%.Also,the wear resistance of the blade milling tool decreases by 102.7%,while the slope milling tool declines by 32.6%when compared with the flat milling tool.Therefore,the slope milling tool has the characteristics of moderate torque,stable working conditions,the highest working efficiency,and fine wear resistance,which is preferably used to mill multistage fracturing ball seats.This study provides a theoretical basis and guidance for milling multistage fracturing ball seats on-site and realizing production with a large diameter in later stages of multistage fracturing wells.
基金supported by the National Natural Science Foundation of China(Grant No.51976149)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(Grant No.2019QNRC001).
文摘Thermal energy storage has been a pivotal technology to fill the gap between energy demands and energy supplies.As a solid-solid phase change material,shape-memory alloys(SMAs)have the inherent advantages of leakage free,no encapsulation,negligible volume variation,as well as superior energy storage properties such as high thermal conductivity(compared with ice and paraffin)and volumetric energy density,making them excellent thermal energy storage materials.Considering these characteristics,the design of the shape-memory alloy based the cold thermal energy storage system for precooling car seat application is introduced in this paper based on the proposed shape-memory alloy-based cold thermal energy storage cycle.The simulation results show that the minimum temperature of the metal boss under the seat reaches 26.2°C at 9.85 s,which is reduced by 9.8°C,and the energy storage efficiency of the device is 66%.The influence of initial temperature,elastocaloric materials,and the shape-memory alloy geometry scheme on the performance of car seat cold thermal energy storage devices is also discussed.Since SMAs are both solid-state refrigerants and thermal energy storage materials,hopefully the proposed concept can promote the development of more promising shape-memory alloy-based cold and hot thermal energy storage devices.
文摘A system for fully automatic selection of welding specifications in resistance welding equipment has been developed to address the problem of workers frequently choosing the wrong specifications during manual welding of multiple parts on a single machine in automobile factories. The system incorporates an automatic recognition system for different workpiece materials using the added machine fixture,visual detection system for nuts and bolts,and secondary graphical confirmation to ensure the correctness of specification calling. This system achieves reliable,fully automatic selection of welding specifications in resistance welding equipment and has shown significant effects in improving welding quality for massproduced workpieces,while solving the problem of specification calling errors that can occur with traditional methods involving process charts and code adjustments. This system is particularly suitable for promoting applications in manual welding of multiple parts on a single machine in automobile factories,ensuring correct specification calling and welding quality.
文摘Noise-reduction seats have been successfully used in concert halls, theaters, and other places that reduce noise. In this study, a new noise-reduction seat design was proposed for high-speed trains, which have unique interior noise spectral characteristics. First, before the noisereduction seat models were fabricated, the parameters of high-performance sound-absorbing materials and perforated plates were selected by conducting a standing-wave tube test. The sound-absorption effects of the noisereduction seats and normal seats were investigated and compared in a reverberation chamber. Test results showed that, compared with normal seats, the noise-reduction seats obtained a significantly improved sound-absorption coefficient in the entire frequency band. Furthermore, the test results were used to establish a simulation model for calculation, and the simulation results proved that the noise-reduction seats substantially reduced the noise in an entire train car. Finally, the noise-reduction seats were fabricated and installed in a full train car of an actual highspeed train. The test results showed that, compared with the normal seats, the noise-reduction seats decreased the noise level at a standard point in the passenger car by 1.5 dB. Therefore, the noise-reduction seats are effective in noise reduction.
文摘Hainan Province has revised its villager committee election methods and procedures to ensure women’s participation in local government wang Saixiao was happy about being reelected as the village head. For six years, Wang, 34, has served as the head of Baotang Village, Lin’gao County of south China’s Hainan Province.
基金This research was funded by the National Natural Science Foundation of China(grant number 51675534).
文摘The sleeve sealing ball seat is one of the important components in the multistage fracturing process of horizontal wells.The erosion and wear of the surface will decrease the sealing performance of the fracturing ball and the ball seat.This leads to pressure leakage during the fracturing process and fracturing failure.In this paper,combined with the actual ball seat materials and working conditions during the fracturing process,the erosion tests of ductile iron and tungsten carbide materials under different erosion speeds,angles,and mortar concentrations are carried out.Then the erosion test results were analyzed by mathematical fitting,and a set of erosion models suitable for sliding sleeve setting ball seat materials were innovatively established.For the first time,this paper combines the erosion model obtained from the experiment and the computational fluid dynamics(CFD)with Fluent software to simulate the erosion of the ball seat.Based on the simulation results,the morphology of the sliding sleeve seat ball after erosion is predicted.Through analysis of the test and simulation results,it is showed that the erosion rate of tungsten carbide material is lower and the wear resistance is better under the condition of small angle erosion.This research can offer a strong basis for fracturing site selection,surface treatment methods,and prediction of failure time of ball seats.
文摘Seasonal adjustment has been widely used in statistic analyses.Nowadays,the research on seasonal adjustment methods mainly concentrates on X-11,X-12 etc in China,lacking the whole understanding of foreign seasonal adjustment methods,and the latest progress of seasonal adjustment methods has been less introduced.In this article,various seasonal adjustment methods were introduced,and a comparison of their characteristics and applications was made.It is helpful that statistical organizations can develop appropriate seasonal adjustment methods,concerning different kinds of data.
基金Deputyship for Research&Innovation,Ministry of Education in Saudi Arabia for funding this research work through Project Number MoE-IF-UJ-22-4100409-1.
文摘Nowadays days,the chief grounds of automobile accidents are driver fatigue and distractions.With the development of computer vision technology,a cutting-edge system has the potential to spot driver distractions or sleepiness and alert them,reducing accidents.This paper presents a novel approach to detecting driver tiredness based on eye and mouth movements and object identification that causes a distraction while operating a motor vehicle.Employing the facial landmarks that the camera picks up and sends to classify using a Convolutional Neural Network(CNN)any changes by focusing on the eyes and mouth zone,precision is achieved.One of the tasks that must be performed in the transit system is seat belt detection to lessen accidents caused by sudden stops or high-speed collisions with other cars.A method is put forth to use convolution neural networks to determine whether the motorist is wearing a seat belt when a driver is sleepy,preoccupied,or not wearing their seat belt,this system alerts them with an alarm,and if they don’t wake up by a predetermined time of 3 s threshold,an automatic message is sent to law enforcement agencies.The suggested CNN-based model exhibits greater accuracy with 97%.It can be utilized to develop a system that detects driver attention or sleeps in real-time.
文摘The purpose of this paper is to present the rationale for registration of the Seated Condylar Position (SCP)/Centric Relation (CR) position of the condyles.
