By focusing on the vulnerability of the structure of marine equipments, together with considering the randomness of meta-ocean load in statistics, a kind of analytical method of fatigue characteristics of marine struc...By focusing on the vulnerability of the structure of marine equipments, together with considering the randomness of meta-ocean load in statistics, a kind of analytical method of fatigue characteristics of marine structure based on full- scale and actual measurement of prototype is proposed. On the basis of short-term field measurement results of structural response, research is carried out on the fatigue analysis of hinge joints at the upper part of the Soft Yoke single point Mooring System （SYMS） by simultaneously monitoring the environmental load and considering the design criteria of offshore structure. Through analysis of finite element modeling, the time-histories of typical stress response are obtained, and then the assessment of fatigue damage at key hinge joints is conducted. The simulation results indicate that the proposed method can accurately analyze the fatigue damage of offshore engineering structure caused by the effect of wave load. The present analytical method of fatigue characteristics can be extended on other offshore engineering structures subjected to meta-ocean load.展开更多
The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods fo...The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods for centroid measurement often necessitate custom equipment and specialized positioning devices,leading to high costs and limited accuracy.Here,we present a centroid measurement method that integrates 3D scanning technology,enabling accurate measurement of centroid across various types of objects without the need for specialized positioning fixtures.A theoretical framework for centroid measurement was established,which combined the principle of the multi-point weighing method with 3D scanning technology.The measurement accuracy was evaluated using a designed standard component.Experimental results demonstrate that the discrepancies between the theoretical and the measured centroid of a standard component with various materials and complex shapes in the X,Y,and Z directions are 0.003 mm,0.009 mm,and 0.105 mm,respectively,yielding a spatial deviation of 0.106 mm.Qualitative verification was conducted through experimental validation of three distinct types.They confirmed the reliability of the proposed method,which allowed for accurate centroid measurements of various products without requiring positioning fixtures.This advancement significantly broadened the applicability and scope of centroid measurement devices,offering new theoretical insights and methodologies for the measurement of complex parts and systems.展开更多
Ventilation characteristic parameters are the base of ventilation network solution; however, they are apt to be affected by operating errors, reading errors, airflow stability, and other factors, and it is difficult t...Ventilation characteristic parameters are the base of ventilation network solution; however, they are apt to be affected by operating errors, reading errors, airflow stability, and other factors, and it is difficult to obtain accurate results. In order to check the ventilation characteristic parameters of mines more accurately, the integrated method of circuit and path is adopted to overcome the drawbacks caused by the traditional path method or circuit method in the digital debugging process of ventilation system, which can improve the large local error or the inconsistency between the airflow direction and the actual situation caused by inaccuracy of the ventilation characteristic parameters or checking in the ventilation network solution. The results show that this method can effectively reduce the local error and prevent the pseudo-airflow reversal phenomenon; in addition, the solution results are consistent with the actual situation of mines, and the effect is obvious.展开更多
This article describes the geographical indication characteristics of Zhuanbu strawberry,a special product of Yinan County,Shandong Province,a national geographical indication agricultural product,including specific p...This article describes the geographical indication characteristics of Zhuanbu strawberry,a special product of Yinan County,Shandong Province,a national geographical indication agricultural product,including specific production area,unique production environment,rich human history and unique product quality,summarizes the unique production method of Zhuanbu strawberry from selection of production area and varieties,production management,timely harvesting and other aspects,and puts forward corresponding industrial development measures,in order to maintain the brand of Zhuanbu strawberry to the greatest extent and further improve the brand awareness and market competitiveness of Zhuanbu strawberry.展开更多
Grains are widely present in industrial productions and processing,and are stored in silos.In the silo,auxiliary structures are added to achieve efficient production.However,little effort has been devoted to the influ...Grains are widely present in industrial productions and processing,and are stored in silos.In the silo,auxiliary structures are added to achieve efficient production.However,little effort has been devoted to the influence of the internal structure of the silo on the granular flow.In this work,a silo with a central decompression tube is studied through experimental measurements and discrete element methods.Then,the influences of the central decompression tube on the flow behavior of grains and wall pressure are analyzed.Results show that the grains are in mass flow in the silo without a central decompression tube,while the grains are in funnel flow in the silo with a central decompression tube.Moreover,regardless of whether there is a central decompression tube in the silo,the maximum pressure appears at the top of the conical silo.In the lower part of the silo,the wall pressure of the silo with a central decompression tube is lower than that of the silo without a central decompression tube.Therefore,a silo with a central decompression tube is more conducive to grain storage and discharge than a silo without a central decompression tube.展开更多
Objective to study an in vitro accurate measurement method for the placement depth of PICC. Methods 270 patients undergoing PICC catheterization under ultrasound guidance in outpatient PICC catheterization from March ...Objective to study an in vitro accurate measurement method for the placement depth of PICC. Methods 270 patients undergoing PICC catheterization under ultrasound guidance in outpatient PICC catheterization from March to September 2019 were selected by convenient sampling. By using the random number table method, the subjects were divided into group A (horizontal L-type measurement method) and Group B (characteristic index measurement calculation) by 1:1, with 135 cases in each group. X-ray chest radiograph was taken after catheterization in both groups, and the indwelling position of the catheter was adjusted according to the X-ray chest radiograph. The correlation between PICC predicted length and ideal depth and patient satisfaction were compared between the two groups. Results The success rate of PICC catheter tip insertion in group B was 97.78%, while that in control group A was 82.22%, the difference was statistically significant (P < 0.05). The satisfaction degree of patients in group B was significantly higher than that in group A. The differences were statistically significant (P < 0.05). Conclusion Improving the success rate of the precise depth of PICC catheter placement can significantly reduce the incidence of complications, waste of human and material resources caused by adjusting the catheter position, and significantly improve patient satisfaction.展开更多
The smart meter communication system has substantial application value for the construction and upgrading of the entire power system.The deployment of the transmitter(Tx)of the smart meter system in the residential sc...The smart meter communication system has substantial application value for the construction and upgrading of the entire power system.The deployment of the transmitter(Tx)of the smart meter system in the residential scenarios is vexed by the need for more theoretical support.This paper mainly studies the communication channel between the Tx at semibasement and receiver(Rx)at outdoor.The design of an effective communication system relies on an accurate understanding of channel characteristics.Channel measurements and ray-tracing channel modeling are conducted to obtain channel data.The influence of different positions at same semi-basement is studied.Typical channel characteristics are analyzed,such as power delay profile(PDP),power angular profile(PAP),root-mean-square(RMS)delay spread(DS),channel capacity,received power,and path loss.The influence of different semi-basement placements and different floor heights is also compared.Besides,the channel measurements and simulation data fit well,which can illustrate the validity and reliability of the acquired channel data.This paper can provide theoretical support for the design and optimization of smart meter communication systems in semi-basement scenarios.展开更多
利用计算机视觉对桥梁结构进行位移测量,常见的方法有特征点算法和光流法。为解决光照变化对光流法的精度影响,以及特征点法难以对目标进行实时跟踪等问题,以定向FAST与旋转BRIEF(oriented FAST and rotated BRIEF,ORB)特征点算法提取...利用计算机视觉对桥梁结构进行位移测量,常见的方法有特征点算法和光流法。为解决光照变化对光流法的精度影响,以及特征点法难以对目标进行实时跟踪等问题,以定向FAST与旋转BRIEF(oriented FAST and rotated BRIEF,ORB)特征点算法提取目标特征点,并结合LK(Lucas-Kanade)光流法进行跟踪。通过两种算法的互补融合,并设定周期性更新策略,有效减少误差积累。在室内进行了钢板梁模型激振试验,探讨光照变化对算法性能的影响。将算法得到的位移数据与激光位移计测量结果进行对比,以验证其准确性。此外,还将该算法与FAST-LK、SIFT-LK、Shi-Tomasi-LK、siamRPN++等算法进行比对分析。结果表明:该算法得到的位移曲线拟合程度在95%以上,误差控制在5%之内,验证了其可行性,同时,试验表明该方法对光照变化具有一定的鲁棒性,并能达到实时性的要求。展开更多
使用由微波接收天线、衰减器、二极管检波器和波形记录等单元组成的测量系统测量高功率微波(high power microwave,HPM)功率是一种常用方法。在外场(尤其冬季),室外环境温度与室内温度相差较大(通常可达30~40℃),必然导致二极管检波器...使用由微波接收天线、衰减器、二极管检波器和波形记录等单元组成的测量系统测量高功率微波(high power microwave,HPM)功率是一种常用方法。在外场(尤其冬季),室外环境温度与室内温度相差较大(通常可达30~40℃),必然导致二极管检波器特性变化。如何有效抑制温度变化引起的二极管检波器特性变化对脉冲微波功率测量结果的影响,是提高此类系统在外场测量HPM功率精度的关键。本文论述了比较法测量脉冲微波功率的原理,理论分析得出,在二极管检波器工作于电压-功率线性区时,比较法测量脉冲微波功率的精度不受检波器温度特性的影响。实验研究了二极管检波器在不同温度条件下,直接检波法和比较法测量微波源输出相同脉冲微波功率的相对偏差变化,直接检波法的偏差为14%,比较法的偏差为−5.3%,测量结果表明运用比较法可以有效减小二极管检波器温度特性变化对测量脉冲微波功率的影响。展开更多
文章对国内多个城市的52个典型地下隧道断面进行了运营期全天连续振动源强测试。基于实测数据集,分析了地铁振动源强的离散性特征及主要影响因素,探讨了离散特性下振动源强的评价方法,提出了基于多层感知器神经网络模型的地铁振动源强...文章对国内多个城市的52个典型地下隧道断面进行了运营期全天连续振动源强测试。基于实测数据集,分析了地铁振动源强的离散性特征及主要影响因素,探讨了离散特性下振动源强的评价方法,提出了基于多层感知器神经网络模型的地铁振动源强预测方法。实测地铁振动源强的离散程度可达20 dB。列车趟次取值对振动源强的稳定性影响很大,采用5趟次和20趟次计算源强平均值,其波动幅度分别达4.5,2.2 dB,而100趟次下波动幅度仅为0.3 d B。车轮不圆度是影响振动源强离散性的主要因素,文章提出的基于多层感知器神经网络的预测模型能较好实现地铁振动源强的预测。展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.15572072)the National Key Basic Research and Development Program(Grant Nos.2014CB046803 and 2016ZX05028-002-005)
文摘By focusing on the vulnerability of the structure of marine equipments, together with considering the randomness of meta-ocean load in statistics, a kind of analytical method of fatigue characteristics of marine structure based on full- scale and actual measurement of prototype is proposed. On the basis of short-term field measurement results of structural response, research is carried out on the fatigue analysis of hinge joints at the upper part of the Soft Yoke single point Mooring System （SYMS） by simultaneously monitoring the environmental load and considering the design criteria of offshore structure. Through analysis of finite element modeling, the time-histories of typical stress response are obtained, and then the assessment of fatigue damage at key hinge joints is conducted. The simulation results indicate that the proposed method can accurately analyze the fatigue damage of offshore engineering structure caused by the effect of wave load. The present analytical method of fatigue characteristics can be extended on other offshore engineering structures subjected to meta-ocean load.
基金supported by National Natural Science Foundation of China(No.52176122).
文摘The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods for centroid measurement often necessitate custom equipment and specialized positioning devices,leading to high costs and limited accuracy.Here,we present a centroid measurement method that integrates 3D scanning technology,enabling accurate measurement of centroid across various types of objects without the need for specialized positioning fixtures.A theoretical framework for centroid measurement was established,which combined the principle of the multi-point weighing method with 3D scanning technology.The measurement accuracy was evaluated using a designed standard component.Experimental results demonstrate that the discrepancies between the theoretical and the measured centroid of a standard component with various materials and complex shapes in the X,Y,and Z directions are 0.003 mm,0.009 mm,and 0.105 mm,respectively,yielding a spatial deviation of 0.106 mm.Qualitative verification was conducted through experimental validation of three distinct types.They confirmed the reliability of the proposed method,which allowed for accurate centroid measurements of various products without requiring positioning fixtures.This advancement significantly broadened the applicability and scope of centroid measurement devices,offering new theoretical insights and methodologies for the measurement of complex parts and systems.
基金Supported by the National Natural Science Foundation of China （61772159）
文摘Ventilation characteristic parameters are the base of ventilation network solution; however, they are apt to be affected by operating errors, reading errors, airflow stability, and other factors, and it is difficult to obtain accurate results. In order to check the ventilation characteristic parameters of mines more accurately, the integrated method of circuit and path is adopted to overcome the drawbacks caused by the traditional path method or circuit method in the digital debugging process of ventilation system, which can improve the large local error or the inconsistency between the airflow direction and the actual situation caused by inaccuracy of the ventilation characteristic parameters or checking in the ventilation network solution. The results show that this method can effectively reduce the local error and prevent the pseudo-airflow reversal phenomenon; in addition, the solution results are consistent with the actual situation of mines, and the effect is obvious.
基金Shandong Provincial Modern Agricultural Industrial Technology System:Project for Construction of Vegetation Innovative Team(SDAIT-05-18).
文摘This article describes the geographical indication characteristics of Zhuanbu strawberry,a special product of Yinan County,Shandong Province,a national geographical indication agricultural product,including specific production area,unique production environment,rich human history and unique product quality,summarizes the unique production method of Zhuanbu strawberry from selection of production area and varieties,production management,timely harvesting and other aspects,and puts forward corresponding industrial development measures,in order to maintain the brand of Zhuanbu strawberry to the greatest extent and further improve the brand awareness and market competitiveness of Zhuanbu strawberry.
基金We would like to acknowledge the finical support by the Key Laboratory of Agro-Products Postharvest Handling,Ministry of Agriculture support(Grant No.KLAPPH2-2017-04).
文摘Grains are widely present in industrial productions and processing,and are stored in silos.In the silo,auxiliary structures are added to achieve efficient production.However,little effort has been devoted to the influence of the internal structure of the silo on the granular flow.In this work,a silo with a central decompression tube is studied through experimental measurements and discrete element methods.Then,the influences of the central decompression tube on the flow behavior of grains and wall pressure are analyzed.Results show that the grains are in mass flow in the silo without a central decompression tube,while the grains are in funnel flow in the silo with a central decompression tube.Moreover,regardless of whether there is a central decompression tube in the silo,the maximum pressure appears at the top of the conical silo.In the lower part of the silo,the wall pressure of the silo with a central decompression tube is lower than that of the silo without a central decompression tube.Therefore,a silo with a central decompression tube is more conducive to grain storage and discharge than a silo without a central decompression tube.
文摘Objective to study an in vitro accurate measurement method for the placement depth of PICC. Methods 270 patients undergoing PICC catheterization under ultrasound guidance in outpatient PICC catheterization from March to September 2019 were selected by convenient sampling. By using the random number table method, the subjects were divided into group A (horizontal L-type measurement method) and Group B (characteristic index measurement calculation) by 1:1, with 135 cases in each group. X-ray chest radiograph was taken after catheterization in both groups, and the indwelling position of the catheter was adjusted according to the X-ray chest radiograph. The correlation between PICC predicted length and ideal depth and patient satisfaction were compared between the two groups. Results The success rate of PICC catheter tip insertion in group B was 97.78%, while that in control group A was 82.22%, the difference was statistically significant (P < 0.05). The satisfaction degree of patients in group B was significantly higher than that in group A. The differences were statistically significant (P < 0.05). Conclusion Improving the success rate of the precise depth of PICC catheter placement can significantly reduce the incidence of complications, waste of human and material resources caused by adjusting the catheter position, and significantly improve patient satisfaction.
基金supported by the Natural Science Foundation of Shandong Province under Grant ZR2024MF062the open research fund of National Mobile Communications Research Laboratory,Southeast University under Grants 2025D03+1 种基金the Future Plan Program for Young Scholars of Shandong University,and the Innovation and Technology Support Program for Young Scholars of Colleges and Universities in Shandong Province under Grant 2022KJ009The B6G R&D Group in Shandong University is greatly thanked for channel measurements.
文摘The smart meter communication system has substantial application value for the construction and upgrading of the entire power system.The deployment of the transmitter(Tx)of the smart meter system in the residential scenarios is vexed by the need for more theoretical support.This paper mainly studies the communication channel between the Tx at semibasement and receiver(Rx)at outdoor.The design of an effective communication system relies on an accurate understanding of channel characteristics.Channel measurements and ray-tracing channel modeling are conducted to obtain channel data.The influence of different positions at same semi-basement is studied.Typical channel characteristics are analyzed,such as power delay profile(PDP),power angular profile(PAP),root-mean-square(RMS)delay spread(DS),channel capacity,received power,and path loss.The influence of different semi-basement placements and different floor heights is also compared.Besides,the channel measurements and simulation data fit well,which can illustrate the validity and reliability of the acquired channel data.This paper can provide theoretical support for the design and optimization of smart meter communication systems in semi-basement scenarios.
文摘利用计算机视觉对桥梁结构进行位移测量,常见的方法有特征点算法和光流法。为解决光照变化对光流法的精度影响,以及特征点法难以对目标进行实时跟踪等问题,以定向FAST与旋转BRIEF(oriented FAST and rotated BRIEF,ORB)特征点算法提取目标特征点,并结合LK(Lucas-Kanade)光流法进行跟踪。通过两种算法的互补融合,并设定周期性更新策略,有效减少误差积累。在室内进行了钢板梁模型激振试验,探讨光照变化对算法性能的影响。将算法得到的位移数据与激光位移计测量结果进行对比,以验证其准确性。此外,还将该算法与FAST-LK、SIFT-LK、Shi-Tomasi-LK、siamRPN++等算法进行比对分析。结果表明:该算法得到的位移曲线拟合程度在95%以上,误差控制在5%之内,验证了其可行性,同时,试验表明该方法对光照变化具有一定的鲁棒性,并能达到实时性的要求。
文摘使用由微波接收天线、衰减器、二极管检波器和波形记录等单元组成的测量系统测量高功率微波(high power microwave,HPM)功率是一种常用方法。在外场(尤其冬季),室外环境温度与室内温度相差较大(通常可达30~40℃),必然导致二极管检波器特性变化。如何有效抑制温度变化引起的二极管检波器特性变化对脉冲微波功率测量结果的影响,是提高此类系统在外场测量HPM功率精度的关键。本文论述了比较法测量脉冲微波功率的原理,理论分析得出,在二极管检波器工作于电压-功率线性区时,比较法测量脉冲微波功率的精度不受检波器温度特性的影响。实验研究了二极管检波器在不同温度条件下,直接检波法和比较法测量微波源输出相同脉冲微波功率的相对偏差变化,直接检波法的偏差为14%,比较法的偏差为−5.3%,测量结果表明运用比较法可以有效减小二极管检波器温度特性变化对测量脉冲微波功率的影响。
文摘文章对国内多个城市的52个典型地下隧道断面进行了运营期全天连续振动源强测试。基于实测数据集,分析了地铁振动源强的离散性特征及主要影响因素,探讨了离散特性下振动源强的评价方法,提出了基于多层感知器神经网络模型的地铁振动源强预测方法。实测地铁振动源强的离散程度可达20 dB。列车趟次取值对振动源强的稳定性影响很大,采用5趟次和20趟次计算源强平均值,其波动幅度分别达4.5,2.2 dB,而100趟次下波动幅度仅为0.3 d B。车轮不圆度是影响振动源强离散性的主要因素,文章提出的基于多层感知器神经网络的预测模型能较好实现地铁振动源强的预测。
