Knowledge of the airflow patterns and methane distributions at a continuous miner face under different ventilation conditions can minimize the risks of explosion and injury to miners by accurately forecasting potentia...Knowledge of the airflow patterns and methane distributions at a continuous miner face under different ventilation conditions can minimize the risks of explosion and injury to miners by accurately forecasting potentially hazardous face methane levels. This study focused on validating a series of computational fluid dynamics(CFD) models using full-scale ventilation gallery data that assessed how curtain setback distance impacted airflow patterns and methane distributions at an empty mining face(no continuous miner present). Three CFD models of face ventilation with 4.6, 7.6 and 10.7 m(15, 25, and 35 ft) blowing curtain setback distances were constructed and validated with experimental data collected in a full-scale ventilation test facility. Good agreement was obtained between the CFD simulation results and this data.Detailed airflow and methane distribution information are provided. Elevated methane zones at the working faces were identified with the three curtain setback distances. Visualization of the setback distance impact on the face methane distribution was performed by utilizing the post-processing capability of the CFD software.展开更多
To study fluctuations of the free surface of liquid steel in the mold,two different models with the same casting conditions but different thicknesses were employed to analyze the hydrodynamic behavior at the top of th...To study fluctuations of the free surface of liquid steel in the mold,two different models with the same casting conditions but different thicknesses were employed to analyze the hydrodynamic behavior at the top of the mold.The first model was a standard thickness slab,and the second had a thickness three times wider.It is found with the second model that above the plane formed by the steel jets,it is possible to observe four three-dimensional vortexes that interact with the submerged entry nozzle（SEN）and mold walls.By using a biphasic model to simulate the interface between the liquid and air inside the mold,the flow asymmetry and the fluctuations of the free surface can be clearly observed.展开更多
The influence of a Reactive Brilliant Red X-3B （RBR X-3B） dye on the peroxidase isoenzyme ofPhanerochaete chrysosporium was determined, and the biofilm structure in a white rot fungal continuous membrane bioreactor ...The influence of a Reactive Brilliant Red X-3B （RBR X-3B） dye on the peroxidase isoenzyme ofPhanerochaete chrysosporium was determined, and the biofilm structure in a white rot fungal continuous membrane bioreactor （MBR） was also investigated by scanning electron microscope （SEM）. The variation of peroxidase isoenzyme and the decolorization rate in the continuous MBR were evaluated. The results showed that the 100 mg/L RBR X-3B could stimulate the production of the peroxidase isoenzyme in the shaking-flask culture. In addition, two new peroxidase isoenzyme bands with relative mobility （Rf） value of 0.27 and 0.28 appeared, but the activity was lower than the blank control of 11 d. In the continuous MBR, the system worked stably during the first 60 d, the main peroxidase isoenzyme bands existed and three new bands with Rf value of 0.10, 0.27, and 0.28 appeared. Meanwhile, the biofilm grew well and the average decolorization rate could reach 90.6%. But the bands of peroxidase isoenzyme decreased rapidly at day 65, only two bands with Rf value 0.24 and 0.26 existed, and the decolorization rate decreased to 78.3%. Therefore, 5 bottles of P. chrysosporium mycelial pellet were added into the MBR, and then the activity of the peroxidase isoenzyme and the decolorization rate had a slight recovery. Finally, the decolorization rate finally decreased to 75.2%. These results contribute to a comprehensive understanding of the variation of peroxidase isoenzyme and biofilm in continuous MBR by white rot fungi.展开更多
To improve the smoothness of motion control in a quadruped robot, a continuous and smooth gait transition method based on central pattern generator （CPG） was presented to solve the unsmooth or failed problem which m...To improve the smoothness of motion control in a quadruped robot, a continuous and smooth gait transition method based on central pattern generator （CPG） was presented to solve the unsmooth or failed problem which may result in phase-locked or sharp point with direct replacement of the gait matrix. Through improving conventional weight matrix, a CPG network and a MATLAB/ Simulink model were constructed based on the Hopf oscillator for gait generation and transition in the quadruped robot. A co-simulation was performed using ADAMS/MATLAB for the gait transition between walk and trot to verify the correctness and effectiveness of the proposed CPG gait generation and transition algorithms. Related methods and conclusions can technically support the motion control technology of the quadruped robot.展开更多
Abstract-The development of asynchronous brain-computer interface （BCI） based on motor imagery （M1） poses the research in algorithms for detecting the nontask states （i.e., idle state） and the design of continuo...Abstract-The development of asynchronous brain-computer interface （BCI） based on motor imagery （M1） poses the research in algorithms for detecting the nontask states （i.e., idle state） and the design of continuous classifiers that classify continuously incoming electroencephalogram （EEG） samples. An algorithm is proposed in this paper which integrates two two-class classifiers to detect idle state and utilizes a sliding window to achieve continuous outputs. The common spatial pattern （CSP） algorithm is used to extract features of EEG signals and the linear support vector machine （SVM） is utilized to serve as classifier. The algorithm is applied on dataset IVb of BCI competition Ⅲ, with a resulting mean square error of 0.66. The result indicates that the proposed algorithm is feasible in the first step of the development of asynchronous systems.展开更多
As to the continuous casting process of low carbon microalloyed steel, subsurface microstructure evolution plays an important role in the slab surface cracking. In order to study the effect of the slab subsurface micr...As to the continuous casting process of low carbon microalloyed steel, subsurface microstructure evolution plays an important role in the slab surface cracking. In order to study the effect of the slab subsurface microstructure evolution on the transverse cracking, three different secondary cooling patterns （i. e. , mild cooling, strong cooling and controlled cooling） were performed in the corresponding slab curved continuous caster. Based on the metallo- graphic results, three transformation regions were found to be formed with the evolution of microstructures at different depths in the slab subsurface. The three regions are strong cooling transformation （SCT） region, double phase transformation （DPT） region and mild cooling transformation （MCT） region, respectively. Meanwhile, it was also found that the crack index used for evaluating slab surface cracking susceptibility was decreased when the range of the DPT region was increased. This can be explained by the fact that the double phase transformation （austenite-ferrite-austenite） occurred resulting from thermal cycling in DPT region, which resulted in promoting the refinement of prior austenite grains and inhibiting the precipitation of film-like ferrite and chain-like precipitates. Under the con- trolled cooling pattern, the widely-distributed DPT region was formed in the range of 3.5--8.0 mm to the slab surface. And compared with other cooling patterns, the cracking susceptibility is lowest with a crack index of 0.4.展开更多
Single-cell imaging,a powerful analytical method to study single-cell behavior,such as gene expression and protein profiling,provides an essential basis for modern medical diagnosis.The coding and localization functio...Single-cell imaging,a powerful analytical method to study single-cell behavior,such as gene expression and protein profiling,provides an essential basis for modern medical diagnosis.The coding and localization function of microfluidic chips has been developed and applied in living single-cell imaging in recent years.Simultaneously,chip-based living single-cell imaging is also limited by complicated trapping steps,low cell utilization,and difficult high-resolution imaging.To solve these problems,an ultra-thin temperature-controllable microwell array chip(UTCMA chip)was designed to develop a living single-cell workstation in this study for continuous on-chip culture and real-time high-resolution imaging of living single cells.The chip-based on ultra-thin ITO glass is highly matched with an inverted microscope(or confocal microscope)with a high magnification objective(100×oil lens),and the temperature of the chip can be controlled by combining it with a home-made temperature control device.High-throughput single-cell patterning is realized in one step when the microwell array on the chip uses hydrophilic glass as the substrate and hydrophobic SU-8 photoresist as the wall.The cell utilization rate,single-cell capture rate,and microwell occupancy rate are all close to 100%in the microwell array.This method will be useful in rare single-cell research,extending its application in the biological and medical-related fields,such as early diagnosis of disease,personalized therapy,and research-based on single-cell analysis.展开更多
High-efficiency production organization should be simple and "laminar". A one to one "laminar flow" operation mechanism is supposed to be accepted as a prerequisite to build high-efficiency clean s...High-efficiency production organization should be simple and "laminar". A one to one "laminar flow" operation mechanism is supposed to be accepted as a prerequisite to build high-efficiency clean steel "production platform". Concerning the fact that establishing a one to one "laminar flow" production pattern is impossible at Tangshan Iron and Steel Co., Ltd., "quasi-laminar flow" production pattern was evaluated. Result shows that rolling bar products of various specifications have great impact on the liquid steel supply model between BOF and CC. Considering the process matching issue of steelmaking-continuous casting-rolling process in bar production line, a "quasi-laminar flow" production pattern between BOF and CC was proposed according to different rolling specification in bar mills. Through analysis and research on current production pattern, combined with principles and strategy for BOF workshop control, and taking the plant layout into account, "quasi-laminar flow" production pattern was finally established. Moreover, Gantt chart of "quasi-laminar flow" production pattern was drawn. It is shown that the relative "order degree" of the "quasi-laminar flow" production pattern rises, which is conductive to production scheduling and ladle operation turnaround in comparison with "turbulence" production pattern. While a careful evaluation should be conducted due to the fluctuant temperature drop caused by the inevitable inserted heats and decreased operation rate of inserted BOF before adapting the production pattern.展开更多
Dear Editor,The brain experiences ongoing changes across different ages to support brain development and functional reorganization.During the span of adulthood,although the brain has matured from a neurobiological per...Dear Editor,The brain experiences ongoing changes across different ages to support brain development and functional reorganization.During the span of adulthood,although the brain has matured from a neurobiological perspective,it is still continuously shaped by external factors such as living habit.展开更多
A Pulse-Width-Modulation-based(PWM-based)continuously variable sprayer was developed using a proportional regulating solenoid valve.Variable flow-rate was obtained by varying the duty cycle of the actuating signal wit...A Pulse-Width-Modulation-based(PWM-based)continuously variable sprayer was developed using a proportional regulating solenoid valve.Variable flow-rate was obtained by varying the duty cycle of the actuating signal with 24 kHz frequency.Flow-rate regulating ranges of the PWM-based continuously variable spray(i.e.the turndown ratio responding to 100%-40%duty cycle)are 7.14:1,3.57:1,and 3.70:1 for flat-fan,hollow-cone and solid-cone nozzles,respectively.The purpose of the study was to evaluate the PWM-based continuously variable spray.The method was to quantify the effects of flow-rate control on spray characteristics in terms of droplet size spectra,spray distribution patterns,and spray angle for flat-fan,hollow-cone,solid-cone nozzles.For all nozzles tested,spray distribution concentrated on the center of the spray field with the decrease of flow-rate.But the spray shape is still symmetrical.The sensitivities of the spray angles to flow-rate were 0.83,0.67,and 0.58(o)/%respectively for flat-fan,hollow-cone and solid-cone nozzles.Compared with the sensitivities of spray angle for PWM-based intermittent variable spray,they are somewhat larger.As flow-rate was reduced from the maximum(100%flow-rate)to the minimum controllable rate,the observed median diameter of spray droplets decreased by 5.4%,9.8%,and 9.9%for flat-fan,hollow-cone and solid-cone nozzles,respectively.This indicates that spray droplet size was affected slightly by flow-rate control.展开更多
黏结漏钢作为最常见的漏钢事故,不仅会损坏连铸设备,甚至威胁操作人员生命安全。常规的漏钢预报模型主要依赖工艺参数的阈值进行判断和简单的统计分析,没有充分利用数据的时序变化,限制了模型的准确性。为了解决上述问题,将鲸鱼优化算法...黏结漏钢作为最常见的漏钢事故,不仅会损坏连铸设备,甚至威胁操作人员生命安全。常规的漏钢预报模型主要依赖工艺参数的阈值进行判断和简单的统计分析,没有充分利用数据的时序变化,限制了模型的准确性。为了解决上述问题,将鲸鱼优化算法(whale optimization algorithm,WOA)和长短期记忆神经网络(long short term memory,LSTM)结合,构建了一种基于深度学习的WOA-LSTM漏钢预报模型。提取温度特征、静态几何特征及动态特征,使用皮尔逊相关系数筛选出与漏钢事故相关性较高的特征参数,包括温升异常和温降区域温度变化率均值、最大值等11个特征。利用鲸鱼优化算法对长短期记忆神经网络的超参数进行寻优,以均方误差作为模型损失函数,通过循环迭代搜索出最优的网络超参数。在模型训练过程中,采用滑动窗口技术输入训练样本,使模型能够更好地学习和捕捉连铸过程中工艺参数的时序变化特征。最后使用某钢厂的实际生产数据进行了试验,与BP(back propagation)、LSTM及WOA-BP模型相比,WOA-LSTM预测模型在多个性能指标上均表现出色,能更精准地捕捉到特征数据的时序变化趋势,且模型的收敛速度快、预测精度高。该模型的报出率为98.4%,预报率为96.8%,能够满足钢厂实际生产的要求。展开更多
文摘Knowledge of the airflow patterns and methane distributions at a continuous miner face under different ventilation conditions can minimize the risks of explosion and injury to miners by accurately forecasting potentially hazardous face methane levels. This study focused on validating a series of computational fluid dynamics(CFD) models using full-scale ventilation gallery data that assessed how curtain setback distance impacted airflow patterns and methane distributions at an empty mining face(no continuous miner present). Three CFD models of face ventilation with 4.6, 7.6 and 10.7 m(15, 25, and 35 ft) blowing curtain setback distances were constructed and validated with experimental data collected in a full-scale ventilation test facility. Good agreement was obtained between the CFD simulation results and this data.Detailed airflow and methane distribution information are provided. Elevated methane zones at the working faces were identified with the three curtain setback distances. Visualization of the setback distance impact on the face methane distribution was performed by utilizing the post-processing capability of the CFD software.
基金support by Universidad Autonoma Metropolitana (Nos.2231207 and 2270303)Sistema Nacional de Investigadores (SNI-CONACYT)
文摘To study fluctuations of the free surface of liquid steel in the mold,two different models with the same casting conditions but different thicknesses were employed to analyze the hydrodynamic behavior at the top of the mold.The first model was a standard thickness slab,and the second had a thickness three times wider.It is found with the second model that above the plane formed by the steel jets,it is possible to observe four three-dimensional vortexes that interact with the submerged entry nozzle（SEN）and mold walls.By using a biphasic model to simulate the interface between the liquid and air inside the mold,the flow asymmetry and the fluctuations of the free surface can be clearly observed.
基金supported by the National High Technology Research and Development Program (863) of China (No. 2006AA06Z331)the National Natural Science Foundation of China (No. 50278034)
文摘The influence of a Reactive Brilliant Red X-3B （RBR X-3B） dye on the peroxidase isoenzyme ofPhanerochaete chrysosporium was determined, and the biofilm structure in a white rot fungal continuous membrane bioreactor （MBR） was also investigated by scanning electron microscope （SEM）. The variation of peroxidase isoenzyme and the decolorization rate in the continuous MBR were evaluated. The results showed that the 100 mg/L RBR X-3B could stimulate the production of the peroxidase isoenzyme in the shaking-flask culture. In addition, two new peroxidase isoenzyme bands with relative mobility （Rf） value of 0.27 and 0.28 appeared, but the activity was lower than the blank control of 11 d. In the continuous MBR, the system worked stably during the first 60 d, the main peroxidase isoenzyme bands existed and three new bands with Rf value of 0.10, 0.27, and 0.28 appeared. Meanwhile, the biofilm grew well and the average decolorization rate could reach 90.6%. But the bands of peroxidase isoenzyme decreased rapidly at day 65, only two bands with Rf value 0.24 and 0.26 existed, and the decolorization rate decreased to 78.3%. Therefore, 5 bottles of P. chrysosporium mycelial pellet were added into the MBR, and then the activity of the peroxidase isoenzyme and the decolorization rate had a slight recovery. Finally, the decolorization rate finally decreased to 75.2%. These results contribute to a comprehensive understanding of the variation of peroxidase isoenzyme and biofilm in continuous MBR by white rot fungi.
基金Supported by the Ministerial Level Advanced Research Foundation(65822576)
文摘To improve the smoothness of motion control in a quadruped robot, a continuous and smooth gait transition method based on central pattern generator （CPG） was presented to solve the unsmooth or failed problem which may result in phase-locked or sharp point with direct replacement of the gait matrix. Through improving conventional weight matrix, a CPG network and a MATLAB/ Simulink model were constructed based on the Hopf oscillator for gait generation and transition in the quadruped robot. A co-simulation was performed using ADAMS/MATLAB for the gait transition between walk and trot to verify the correctness and effectiveness of the proposed CPG gait generation and transition algorithms. Related methods and conclusions can technically support the motion control technology of the quadruped robot.
基金supported by the National Natural Science Foundation of China under Grant No. 30525030, 60736029, 60701015, and 30870655.
文摘Abstract-The development of asynchronous brain-computer interface （BCI） based on motor imagery （M1） poses the research in algorithms for detecting the nontask states （i.e., idle state） and the design of continuous classifiers that classify continuously incoming electroencephalogram （EEG） samples. An algorithm is proposed in this paper which integrates two two-class classifiers to detect idle state and utilizes a sliding window to achieve continuous outputs. The common spatial pattern （CSP） algorithm is used to extract features of EEG signals and the linear support vector machine （SVM） is utilized to serve as classifier. The algorithm is applied on dataset IVb of BCI competition Ⅲ, with a resulting mean square error of 0.66. The result indicates that the proposed algorithm is feasible in the first step of the development of asynchronous systems.
基金Item Sponsored by National Natural Science Foundation of China(51174242)
文摘As to the continuous casting process of low carbon microalloyed steel, subsurface microstructure evolution plays an important role in the slab surface cracking. In order to study the effect of the slab subsurface microstructure evolution on the transverse cracking, three different secondary cooling patterns （i. e. , mild cooling, strong cooling and controlled cooling） were performed in the corresponding slab curved continuous caster. Based on the metallo- graphic results, three transformation regions were found to be formed with the evolution of microstructures at different depths in the slab subsurface. The three regions are strong cooling transformation （SCT） region, double phase transformation （DPT） region and mild cooling transformation （MCT） region, respectively. Meanwhile, it was also found that the crack index used for evaluating slab surface cracking susceptibility was decreased when the range of the DPT region was increased. This can be explained by the fact that the double phase transformation （austenite-ferrite-austenite） occurred resulting from thermal cycling in DPT region, which resulted in promoting the refinement of prior austenite grains and inhibiting the precipitation of film-like ferrite and chain-like precipitates. Under the con- trolled cooling pattern, the widely-distributed DPT region was formed in the range of 3.5--8.0 mm to the slab surface. And compared with other cooling patterns, the cracking susceptibility is lowest with a crack index of 0.4.
基金supported by the National Natural Science Foundation of China(Nos.21625501,21936001)the Beijing Outstanding Young Scientist Program(No.BJJWZYJH01201910005017).
文摘Single-cell imaging,a powerful analytical method to study single-cell behavior,such as gene expression and protein profiling,provides an essential basis for modern medical diagnosis.The coding and localization function of microfluidic chips has been developed and applied in living single-cell imaging in recent years.Simultaneously,chip-based living single-cell imaging is also limited by complicated trapping steps,low cell utilization,and difficult high-resolution imaging.To solve these problems,an ultra-thin temperature-controllable microwell array chip(UTCMA chip)was designed to develop a living single-cell workstation in this study for continuous on-chip culture and real-time high-resolution imaging of living single cells.The chip-based on ultra-thin ITO glass is highly matched with an inverted microscope(or confocal microscope)with a high magnification objective(100×oil lens),and the temperature of the chip can be controlled by combining it with a home-made temperature control device.High-throughput single-cell patterning is realized in one step when the microwell array on the chip uses hydrophilic glass as the substrate and hydrophobic SU-8 photoresist as the wall.The cell utilization rate,single-cell capture rate,and microwell occupancy rate are all close to 100%in the microwell array.This method will be useful in rare single-cell research,extending its application in the biological and medical-related fields,such as early diagnosis of disease,personalized therapy,and research-based on single-cell analysis.
文摘High-efficiency production organization should be simple and "laminar". A one to one "laminar flow" operation mechanism is supposed to be accepted as a prerequisite to build high-efficiency clean steel "production platform". Concerning the fact that establishing a one to one "laminar flow" production pattern is impossible at Tangshan Iron and Steel Co., Ltd., "quasi-laminar flow" production pattern was evaluated. Result shows that rolling bar products of various specifications have great impact on the liquid steel supply model between BOF and CC. Considering the process matching issue of steelmaking-continuous casting-rolling process in bar production line, a "quasi-laminar flow" production pattern between BOF and CC was proposed according to different rolling specification in bar mills. Through analysis and research on current production pattern, combined with principles and strategy for BOF workshop control, and taking the plant layout into account, "quasi-laminar flow" production pattern was finally established. Moreover, Gantt chart of "quasi-laminar flow" production pattern was drawn. It is shown that the relative "order degree" of the "quasi-laminar flow" production pattern rises, which is conductive to production scheduling and ladle operation turnaround in comparison with "turbulence" production pattern. While a careful evaluation should be conducted due to the fluctuant temperature drop caused by the inevitable inserted heats and decreased operation rate of inserted BOF before adapting the production pattern.
基金supported by the National Natural Science Foundation of China(61971420)Beijing Brain Initiative of the Beijing Municipal Science and Technology Commission(Z181100001518003)+1 种基金Special Projects of Brain Science of the Beijing Municipal Science and Technology Commission(Z161100000216139)International Cooperation and Exchange of the National Natural Science Foundation of China(31620103905).
文摘Dear Editor,The brain experiences ongoing changes across different ages to support brain development and functional reorganization.During the span of adulthood,although the brain has matured from a neurobiological perspective,it is still continuously shaped by external factors such as living habit.
文摘A Pulse-Width-Modulation-based(PWM-based)continuously variable sprayer was developed using a proportional regulating solenoid valve.Variable flow-rate was obtained by varying the duty cycle of the actuating signal with 24 kHz frequency.Flow-rate regulating ranges of the PWM-based continuously variable spray(i.e.the turndown ratio responding to 100%-40%duty cycle)are 7.14:1,3.57:1,and 3.70:1 for flat-fan,hollow-cone and solid-cone nozzles,respectively.The purpose of the study was to evaluate the PWM-based continuously variable spray.The method was to quantify the effects of flow-rate control on spray characteristics in terms of droplet size spectra,spray distribution patterns,and spray angle for flat-fan,hollow-cone,solid-cone nozzles.For all nozzles tested,spray distribution concentrated on the center of the spray field with the decrease of flow-rate.But the spray shape is still symmetrical.The sensitivities of the spray angles to flow-rate were 0.83,0.67,and 0.58(o)/%respectively for flat-fan,hollow-cone and solid-cone nozzles.Compared with the sensitivities of spray angle for PWM-based intermittent variable spray,they are somewhat larger.As flow-rate was reduced from the maximum(100%flow-rate)to the minimum controllable rate,the observed median diameter of spray droplets decreased by 5.4%,9.8%,and 9.9%for flat-fan,hollow-cone and solid-cone nozzles,respectively.This indicates that spray droplet size was affected slightly by flow-rate control.
文摘黏结漏钢作为最常见的漏钢事故,不仅会损坏连铸设备,甚至威胁操作人员生命安全。常规的漏钢预报模型主要依赖工艺参数的阈值进行判断和简单的统计分析,没有充分利用数据的时序变化,限制了模型的准确性。为了解决上述问题,将鲸鱼优化算法(whale optimization algorithm,WOA)和长短期记忆神经网络(long short term memory,LSTM)结合,构建了一种基于深度学习的WOA-LSTM漏钢预报模型。提取温度特征、静态几何特征及动态特征,使用皮尔逊相关系数筛选出与漏钢事故相关性较高的特征参数,包括温升异常和温降区域温度变化率均值、最大值等11个特征。利用鲸鱼优化算法对长短期记忆神经网络的超参数进行寻优,以均方误差作为模型损失函数,通过循环迭代搜索出最优的网络超参数。在模型训练过程中,采用滑动窗口技术输入训练样本,使模型能够更好地学习和捕捉连铸过程中工艺参数的时序变化特征。最后使用某钢厂的实际生产数据进行了试验,与BP(back propagation)、LSTM及WOA-BP模型相比,WOA-LSTM预测模型在多个性能指标上均表现出色,能更精准地捕捉到特征数据的时序变化趋势,且模型的收敛速度快、预测精度高。该模型的报出率为98.4%,预报率为96.8%,能够满足钢厂实际生产的要求。
