Simultaneous photoacoustic and ultrasound(PAUS)imaging has attracted increasing attention in biomedical research to probe the optical and mechanical properties of tissue.However,the resolution for majority of the exis...Simultaneous photoacoustic and ultrasound(PAUS)imaging has attracted increasing attention in biomedical research to probe the optical and mechanical properties of tissue.However,the resolution for majority of the existing PAUS systems is on the order of 1 mm as the majority are designed for clinical use with low-frequency US detection.Here we developed a concurrent PAUS microscopy that consists of optical-resolution photoacoustic microscopy(OR-PAM)and high-frequency US pulse-echo imaging.This dual-modality system utilizes a novel coaxial dual-element ultrasonic transducer(DE-UST)and provides anatomical and functional information with complementary contrast mechanisms,achieving a spatial resolution of 7μm for PA imaging and 106μm for US imaging.We performed phantom studies to validate the system’s performance.The vasculature of a mouse’s hind paw was imaged to demonstrate the potential of this hybrid system for biomedical applications.展开更多
为研究割草除根松土一体式刀片结构参数对其作业性能的影响,基于离散元法(discrete element method,EDEM)软件建立三维离散元仿真模型,模拟刀片在刨土作业过程中的破土效果。通过单因素试验分析前进速度、旋转速度及刀片倾角对破土率的...为研究割草除根松土一体式刀片结构参数对其作业性能的影响,基于离散元法(discrete element method,EDEM)软件建立三维离散元仿真模型,模拟刀片在刨土作业过程中的破土效果。通过单因素试验分析前进速度、旋转速度及刀片倾角对破土率的影响规律,进一步采用Box-Behnken正交试验结合响应面分析法建立破土率预测模型并进行参数优化。正交试验结果表明,刀片倾角是影响破土率的主要因素,其次为旋转速度,三因素交互作用亦具有显著性。在最优参数组合下,前进速度1.39 m/s、旋转速度107 rad/s、刀片倾角4.7°,破土率达到78.3%。研究结果为山地割草除根松土装置的结构设计与参数配置提供理论依据和实践指导。展开更多
High-capacity Ni-rich layered cathodes LiNi_(x)CoyMn_(1-x-y)O_(2)(NCM)have been widely recognized as highly promising candidates for lithium-ion batteries(LIBs).However,NCM cathodes are suffered from sluggish Li-ion k...High-capacity Ni-rich layered cathodes LiNi_(x)CoyMn_(1-x-y)O_(2)(NCM)have been widely recognized as highly promising candidates for lithium-ion batteries(LIBs).However,NCM cathodes are suffered from sluggish Li-ion kinetics and fast capacity decay.Herein,the Nb/Ti co-doping strategy has been proposed by formation energy analysis to enhance the mechanical and chemical integrities of NCM cathode.Nb/Ti co-doping facilitates Li-ion transport of NCM cathode for boosting the rate ability.Furthermore,the structure stability is prominently improved for the stronger Nb–O and Ti–O bonds,resulting from the suppressed sharp contraction of c axis,inhibited microcracks formation,and alleviated electrolyte corrosion.Inspired by the synergistic effect of Nb/Ti co-doping,the modified NCM exhibits superior comprehensive electrochemical performances.The Nb/Ti co-doping NCM exhibits an increased discharge capacity of 144.3 m Ah/g at10 C and an outstanding capacity retention remained 92.7%after 300 cycles at 1 C.This work offers a promising approach to developing high-performance cathode materials.展开更多
为增强振动筛的处理能力,满足钻采过程中的不同工况需求,改善现有钻井液振动筛存在的“筛堵”“跑浆”等问题,提出了一种“直线+变椭圆”的双轨迹钻井液振动筛,并基于离散元方法 (discrete element method, DEM)耦合多体系统动力学(dyna...为增强振动筛的处理能力,满足钻采过程中的不同工况需求,改善现有钻井液振动筛存在的“筛堵”“跑浆”等问题,提出了一种“直线+变椭圆”的双轨迹钻井液振动筛,并基于离散元方法 (discrete element method, DEM)耦合多体系统动力学(dynamics of multi-body system,MBD)的研究方法,对双轨迹振动筛和岩屑颗粒进行联合仿真计算。探究了2种振型下筛网面上的运动轨迹与抛掷指数、筛分过程中多种岩屑颗粒的运动行为以及筛分性能。研究结果发现:变椭圆轨迹下从入料端至出料端筛面的抛掷指数和振动方向角逐渐减小,有利于实现入料端钻井液固液分离与液相透筛,降低出料端岩屑颗粒的破碎和堵筛概率;稳定筛分时,易透筛颗粒基本处于料层底部或已经透筛,难透筛和不透筛颗粒处于料层的中上层;变椭圆轨迹下多种岩屑颗粒的透筛率均高于直线轨迹、平均透筛时间均短于直线轨迹、平均运移速度均大于直线轨迹。研究成果可为钻井液振动筛的性能提升提供参考。展开更多
文摘Simultaneous photoacoustic and ultrasound(PAUS)imaging has attracted increasing attention in biomedical research to probe the optical and mechanical properties of tissue.However,the resolution for majority of the existing PAUS systems is on the order of 1 mm as the majority are designed for clinical use with low-frequency US detection.Here we developed a concurrent PAUS microscopy that consists of optical-resolution photoacoustic microscopy(OR-PAM)and high-frequency US pulse-echo imaging.This dual-modality system utilizes a novel coaxial dual-element ultrasonic transducer(DE-UST)and provides anatomical and functional information with complementary contrast mechanisms,achieving a spatial resolution of 7μm for PA imaging and 106μm for US imaging.We performed phantom studies to validate the system’s performance.The vasculature of a mouse’s hind paw was imaged to demonstrate the potential of this hybrid system for biomedical applications.
文摘为研究割草除根松土一体式刀片结构参数对其作业性能的影响,基于离散元法(discrete element method,EDEM)软件建立三维离散元仿真模型,模拟刀片在刨土作业过程中的破土效果。通过单因素试验分析前进速度、旋转速度及刀片倾角对破土率的影响规律,进一步采用Box-Behnken正交试验结合响应面分析法建立破土率预测模型并进行参数优化。正交试验结果表明,刀片倾角是影响破土率的主要因素,其次为旋转速度,三因素交互作用亦具有显著性。在最优参数组合下,前进速度1.39 m/s、旋转速度107 rad/s、刀片倾角4.7°,破土率达到78.3%。研究结果为山地割草除根松土装置的结构设计与参数配置提供理论依据和实践指导。
基金supported by the National Natural Science Foundation of China(Nos.52374299,52304320 and 52204306)Outstanding Youth Foundation of Hunan Province(No.2023JJ10044)+1 种基金Key Project of Hunan Provincial Department of Education(No.22A0211)Natural Science Foundation of Hunan Province(No.2023JJ40014)。
文摘High-capacity Ni-rich layered cathodes LiNi_(x)CoyMn_(1-x-y)O_(2)(NCM)have been widely recognized as highly promising candidates for lithium-ion batteries(LIBs).However,NCM cathodes are suffered from sluggish Li-ion kinetics and fast capacity decay.Herein,the Nb/Ti co-doping strategy has been proposed by formation energy analysis to enhance the mechanical and chemical integrities of NCM cathode.Nb/Ti co-doping facilitates Li-ion transport of NCM cathode for boosting the rate ability.Furthermore,the structure stability is prominently improved for the stronger Nb–O and Ti–O bonds,resulting from the suppressed sharp contraction of c axis,inhibited microcracks formation,and alleviated electrolyte corrosion.Inspired by the synergistic effect of Nb/Ti co-doping,the modified NCM exhibits superior comprehensive electrochemical performances.The Nb/Ti co-doping NCM exhibits an increased discharge capacity of 144.3 m Ah/g at10 C and an outstanding capacity retention remained 92.7%after 300 cycles at 1 C.This work offers a promising approach to developing high-performance cathode materials.
文摘为增强振动筛的处理能力,满足钻采过程中的不同工况需求,改善现有钻井液振动筛存在的“筛堵”“跑浆”等问题,提出了一种“直线+变椭圆”的双轨迹钻井液振动筛,并基于离散元方法 (discrete element method, DEM)耦合多体系统动力学(dynamics of multi-body system,MBD)的研究方法,对双轨迹振动筛和岩屑颗粒进行联合仿真计算。探究了2种振型下筛网面上的运动轨迹与抛掷指数、筛分过程中多种岩屑颗粒的运动行为以及筛分性能。研究结果发现:变椭圆轨迹下从入料端至出料端筛面的抛掷指数和振动方向角逐渐减小,有利于实现入料端钻井液固液分离与液相透筛,降低出料端岩屑颗粒的破碎和堵筛概率;稳定筛分时,易透筛颗粒基本处于料层底部或已经透筛,难透筛和不透筛颗粒处于料层的中上层;变椭圆轨迹下多种岩屑颗粒的透筛率均高于直线轨迹、平均透筛时间均短于直线轨迹、平均运移速度均大于直线轨迹。研究成果可为钻井液振动筛的性能提升提供参考。
