Wall slip behavior of cemented paste backfill slurry during pipeline based on noncontact experimental detection

Wall slip is a microscopic phenomenon of cemented paste backfill(CPB)slurry near the pipe wall,which has an important influence on the form of slurry pipe transport flow and velocity distribution.Directly probing the wall slip characteristics using conventional experimental methods is difficult.Therefore,this paper established a noncontact experimental platform for monitoring the microscopic slip layer of CPB pipeline transport independently based on particle image velocimetry(PIV)and analyzed the effects of slurry temperature,pipe diameter,solid concentration,and slurry flow on the wall slip velocity of the CPB slurry,which refined the theory of the effect of wall slip characteristics on pipeline transport.The results showed that the CPB slurry had an extensive slip layer at the pipe wall with significant wall slip.High slurry temperature improved the degree of particle Brownian motion within the slurry and enhanced the wall slip effect.Increasing the pipe diameter was not conducive to the formation of the slurry slip layer and led to a transition in the CPB slurry flow pattern.The increase in the solid concentration raised the interlayer shear effect of CPB slurry flow and the slip velocity.The slip velocity value increased from 0.025 to 0.056 m·s^(-1)when the solid content improved from 55wt%to 65wt%.When slurry flow increased,the CPB slurry flocculation structure changed,which affected the slip velocity,and the best effect of slip layer resistance reduction was achieved when the transported flow rate was 1.01 m^(3)·h^(-1).The results had important theoretical significance for improving the stability and economy of the CPB slurry in the pipeline.

非接触式生理心理检测在长期模拟失重效应分析中的应用研究

目的在模拟失重生理效应场景下,构建基于面部视频的非接触式生理心理检测模型,探索长期模拟失重生理效应分析的非接触式心率和负性心境状态检测新方法。方法搭建可见光和热红外视频融合分析的非接触式生理心理数据采集系统,采集“地星二号”90 d头低位卧床实验中受试者生理心理相关数据,构建基于图卷积网络面部多区域特征融合的非接触式心率检测模型和考虑数据可靠性的非接触式负性心境状态检测模型,并以指夹式心率和POMS-SF量表为标签,验证模型的有效性。结果研究结果显示,非接触式心率检测模型的Bland-Altman图差值平均数为-1.26 bpm,且96.3%的误差值检测数据处于95%一致性区间内,模型检测的心率与指夹式心率有较高的一致性;非接触式负性心境状态检测模型对于紧张、压抑、愤怒、疲劳的检测准确率均超过0.85,且心率、AU06、眼部视线、头部姿态对心境状态检测的影响显著。结论非接触式生理心理检测方法不仅能够用于长期模拟失重的生理效应分析,还可为未来长期空间飞行的航天员在轨健康保障提供新途径。

大直径孔轴线快速测量方法

针对航空制造现场的大直径孔轴线测量难题,提出一种基于光电检测技术和准直激光的孔轴线测量方法。首先,使测头在被测孔内稳定支撑,以单模光纤激光器发出的准直光束作为测量基准,测头前端的PSD传感器测量准直激光光斑坐标,以确定测头相对位置,同时,通过倾角传感器数据修正装夹姿态误差;然后,以激光测距传感器在电机驱动下旋转并测量孔轮廓点的距离,结合电机内部角度编码器的数据,计算出被测孔在当前截面上的中心坐标,移动测头依次测量多个截面;最后,根据所有截面的中心,评定出被测孔的轴线。实验结果表明,本系统轴线测量重复性误差小于0.01 mm,满足一般大直径孔轴线测量要求。

Design and application of thickness measurement calibration system based on laser displacement sensor

This study aims to improve the accuracy and safety of steel plate thickness calibration.A differential noncontact thickness measurement calibration system based on laser displacement sensors was designed to address the problems of low precision of traditional contact thickness gauges and radiation risks of radiation-based thickness gauges.First,the measurement method and measurement structure of the thickness calibration system were introduced.Then,the hardware circuit of the thickness system was established based on the STM32 core chip.Finally,the system software was designed to implement system control to filter algorithms and human-computer interaction.Experiments have proven the excellent performance of the differential noncontact thickness measurement calibration system based on laser displacement sensors,which not only considerably improves measurement accuracy but also effectively reduces safety risks during the measurement process.The system offers guiding significance and application value in the field of steel plate production and processing.

基于计算机视觉的结构多测点位移与振动特性非接触测量方法

位移是衡量结构舒适性与安全性的一个关键参数,但传统接触式方法测量效率低、成本高且难以精确测量稠密测点位移。为解决以上问题,提出了基于计算机视觉与自适应变分模态分解的结构多测点位移和振动特性非接触测量方法。该方法利用高速摄像机获取冲击力锤作用下悬臂梁振动图像,通过有标靶和无标靶特征检测算法,获取结构在冲击载荷下的动态位移曲线,进一步提出了基于变分模态分解和希尔伯特变换的结构振动频率、阻尼比高精度识别方法。所提出方法利用悬臂梁非接触振动测量试验进行了验证,结果表明:通过圆心检测算法和图像特征检测算法提取位移的最大测量误差分别为0.093 mm和0.046 mm,证明了图像特征检测算法的位移提取精度更高;同时,利用变分模态分解方法对测量的位移信号进行了分离并识别结构振动特征,采用圆心检测和图像特征提取算法获取位移识别的固有频率、阻尼比基本一致。研究成果可为突发事件下桥梁结构多点位移高精度监测与振动特性识别提供一种新的方法,具有成本低、使用方便和测点布设灵活等优势。

非接触式全视野镜在增生期糖尿病性视网膜病变患者治疗中的临床效果

目的:分析非接触式全视野镜在增生期糖尿病性视网膜病变(PDR)患者治疗中的临床效果。方法:选取2019年1月—2023年6月荆州市第三人民医院收治的120例PDR患者作为研究对象,共240眼。根据随机数表法分为试验组和对照组,每组各60例。对照组使用25 G玻璃体切除系统行微创玻璃体切除术,试验组在对照组基础上联合使用非接触式全视野镜。比较两组患者围手术期指标、最佳矫正视力(BCVA)、黄斑中心视网膜厚度(CMT)、血管内皮生长因子(VEGF)、内皮素(ET)-1水平及术后并发症情况。结果:试验组手术时间明显少于对照组,差异有统计学意义(P<0.05);试验组治疗后BCVA、CMT数值明显低于对照组,差异有统计学意义(P<0.05);试验组治疗后VEGF、ET-1水平明显低于对照组,差异有统计学意义(P<0.05);试验组并发症总发生率为5.00%,对照组为9.17%,试验组低于对照组,差异无统计学意义(P>0.05)。结论:将非接触式全视野镜应用于PDR患者治疗中有利于缩短手术时间,提高术后视力,降低VEGF、ET-1水平,安全可行。

基于无人机航测的自然崩落法采矿地表塌陷规律研究

自然崩落采矿法会造成一定范围的地表塌陷,是矿山的重大安全隐患。无人机航测在大面积复杂地表监测方面具有安全性好、作业流程简单及精度高的优点,是地表塌陷监测和三维建模的优选技术手段。针对国内最大的自然崩落法矿山,运用无人机航测对该矿山自然崩落法开采诱发的地表塌陷进行非接触监测,开发了无人机航测技术流程,提出了基于无人机航测的地表塌陷三维建模方法,以及三维建模精度分析方法。通过构建三维模型,进行地表塌陷影响区范围分析和塌陷影响区剖面数据分析以及地表塌陷理论分析,研究该矿山2022年3月至2023年3月塌陷区的变化,得到塌陷区变化特点和规律;采用概率积分法对地表塌陷规律进行预测,得出该矿山地表塌陷概率积分法预测值与实测值之间的误差小于0.18 m。研究结果可为该矿山地表治理和泥石流防治提供依据。

Multifunctional Flexible Humidity Sensor Systems Towards Noncontact Wearable Electronics

In the past decade,the global industry and research attentions on intelligent skin-like electronics have boosted their applications in diverse fields including human healthcare,Internet of Things,human–machine interfaces,artificial intelligence and soft robotics.Among them,flexible humidity sensors play a vital role in noncontact measurements relying on the unique property of rapid response to humidity change.This work presents an overview of recent advances in flexible humidity sensors using various active functional materials for contactless monitoring.Four categories of humidity sensors are highlighted based on resistive,capacitive,impedance-type and voltage-type working mechanisms.Furthermore,typical strategies including chemical doping,structural design and Joule heating are introduced to enhance the performance of humidity sensors.Drawing on the noncontact perception capability,human/plant healthcare management,human-machine interactions as well as integrated humidity sensor-based feedback systems are presented.The burgeoning innovations in this research field will benefit human society,especially during the COVID-19 epidemic,where cross-infection should be averted and contactless sensation is highly desired.

Experimental study of noncontact ultrasonic motor with non-symmetrical electrode

We have proposed a novel noncontact ultrasonic motor based on non-syinmetrical electrode driving. The configuration of this electrode and the fabrication process of rotors are presented. Its vibration characteristics are computed and analysed by using the finite element method and studied experimentally. Good agreement between them is obtained. Moreover, it is also shown that this noncontact ultrasonic motor is operated in antisymmetric radial vibration mode of B21 mode. The maximum revolution speed for three-blade and six-blade rotors are 5100 and 3700r/min at an input voltage of 20V, respectively. Also, the noncontact high-speed revolution of the rotors can be realized by the parts of Ⅰ, Ⅲ of the electrode or Ⅱ, Ⅳ of the electrode. The levitation distance between the s tator and rotor is about 140μm according to the theoretical calculation and the experimental measurement.

Noncontact Driving System Using Induction-Based Method and Integrated Piezoelectric Ultrasonic Transducers

Integrated Ultrasonic Transducers (IUTs) have been developed for high-temperature nondestructive evaluation applications. In many field, it would be helpful if a pipe covered by a protective layer of about 10 cm thickness, which is under operation at several hundred Celsius, could be inspected from above the protective layer by an IUT. As a first step toward achieving the inspection of such a pipeline, an induction-based method using coils is presented together with IUTs. This study focuses on the effects of the separation distance (liftoff) between the coils on the ultrasonic signal strength and bandwidth of the IUTs. Ultrasonic signals were generated and received by the IUTs on a steel plate with a sufficient strength for thickness measurements when the liftoff was 20 cm. It was also shown that a ferrite disc together with the coils enhanced the received signal strength even when the liftoff was over 10 cm.

Effects of baffie and intraocular pressure on aerosols generated in the noncontact tonometer measurement during COVID-19

AIM: To investigate the effects of baffle and intraocular pressure(IOP) on the aerosols generated in the noncontact tonometer(NCT) measurement and provide recommendations for the standardized use of the NCT during coronavirus disease 2019(COVID-19). METHODS: This clinical trial included 252 subjects(312 eyes) in The Eye Hospital, Wenzhou Medical University from March 7, 2020, to March 28, 2020. Sixty subjects(120 eyes) with normal IOP were divided into two groups. One group used an NCT without a baffle, another group used an NCT with a baffle. Another 192 subjects(192 eyes) were divided into four groups: Group A;(without a baffle+normal IOP), Group A;(without a baffle+high IOP), Group B;(with a baffle+normal IOP) and Group B;(with a baffle+high IOP). Particulate matter(PM) 2.5 and PM10 generated by all subjects were quantified during the NCT measurement. The IOP values were recorded simultaneously. Effects of baffle and IOP on aerosols generated during the NCT measurement were analyzed.RESULTS: In the normal eye group with a baffle, the aerosol density decreased in a wave-like shape near the NCT with the increase in the number of people measured for IOP, demonstrating no cumulative effect. However, in the normal eye group without a baffle, there was a cumulative effect. PM2.5 and PM10 in Group A;were higher than Group A;(both P<0.001). The PM2.5 and PM10 in Group B;were higher than Group B;(P<0.01, P<0.001 respectively). The PM10 of Group B;was lower than Group A;(P<0.01). PM2.5 in Group B;were lower than Group A;(P<0.01). The median of per capita PM2.5 and PM10 in the combined Group A;+A;were 0.80 and 1.10 μg/m;respectively, which were higher than 0.20 and 0.60 μg/m;in the combined Group B;+B;(both P<0.01). The median of per capita PM2.5 and PM10 in the combined Group A;+B;were 0.10 and 0.20 μg/m;respectively, which were lower than 1.30 and 1.70 μg/m;in the combined Group A;+B;(both P<0.001).CONCLUSION: More aerosols could be generated in patients with high IOP. After the NCT is equipped with a baffle, per capita aerosol density generated decreased significantly near the NCT;And with the increase in the number of people measured for IOP, the aerosols gradually dissipated near the NCT, demonstrating no cumulative effect. Therefore, it is suggested that the NCT should be equipped with a baffle, especially for patients with high IOP.

Noncontact Monitoring of Relative Changes in Blood Pressure Using Microwave Radar Sensors

This study aims to confirm whether noncontact monitoring of relative changes in blood pressure can be estimated using microwave radar sensors. First, an equation to estimate blood pressure was derived, after which, the effectiveness of the estimation equation was confirmed using data obtained by a noncontact method while inducing variations in blood pressure. We considered that the Bramwell-Hill equation, which contains some parameters that directly indicate changes in blood pressure, would be an appropriate reference to construct an estimation equation for the noncontact method, because measurements using microwave radar sensors can measure minute scale motion on the skin surface induced by the pulsation of blood vessels. In order to estimate relative changes in blood pressure, we considered a simple equation including the pulse transit time (PTT), amplitude of signals and body dimensions as parameters. To verify the effectiveness of the equation for estimating changes in blood pressure, two experiments were conducted: a cycling task using an ergometer, which induces blood pressure fluctuations because of changes in cardiac output, and a task using the Valsalva maneuver, which induces blood pressure fluctuations because of changes in vascular resistance. The results obtained from the two experiments suggested that the proposed equation using microwave radar sensors can accurately estimate relative changes of blood pressure. In particular, relatively favorable results were obtained for the changes in blood pressure induced by the changes in cardiac volume. Although many issues remain, this method could be expected to contribute to the continuous evaluation of cardiac function while reducing the burden on patients.

Performance of Array-Type Noncontact End Gripper Based on Coanda Mechanism for Gripping Garment Fabrics

To increase the gripping area of noncontact end grippers(NCEGs), an array-type NCEG based on the Coanda mechanism is proposed, and its performance in gripping different garment fabrics(GFs) is studied. Firstly, the structure and the working mechanism of a single Coanda-based NCEG were analyzed. Secondly, four such grippers were arranged in array to form a minimum gripping unit. Then, the structure of the connecting plate(CP) to the gripper was optimized by simulation analysis to exclude airflow interference, and the adsorption performance of GFs with different fabric parameters was measured. Finally, the experimental results were analyzed to verify the scientific validity and the feasibility of the array-type arrangement. The results show that compared with other NCEGs, the array-type ones based on the Coanda mechanism are better at gripping various large-area GFs and offer better adsorption performance. This innovation provides a new solution to the problem of insufficient gripping area in GF gripping and is very important for improving the production efficiency of garment processing.

A Single-Finger Operated Noncontact User Interface

A noncontact user interface using image processing for people with neuromuscular diseases is presented in this paper. The user interface is composed of a Web camera and a PC, and allows users to manipulate the PC using small movements of single finger. By using image processing techniques with the Web camera, the finger is appropriately detected from the images captured by it. Control boxes for pointing and text input functions are also made. To verify performances of the interface, some tasks are experimentally performed by three able-bodied subjects and a person suffering from spinal muscular atrophy. It was clear from the experimental results that all the subjects could smoothly nerforrn the t,~k~

面向卫星通信的内导体非接触同轴接头设计方法

针对无源互调(PIM)严重影响卫星通信系统性能和稳定性问题,提出了一种利用内导体非接触式结构实现低PIM的同轴接头设计方法。设计并实现了2款分别工作在S波段和C波段的内导体非接触式同轴接头:S波段的内导体非接触式同轴接头在2.1~2.7 GHz下实测|S_(11)|<-30 dB,通带内插入损耗小于0.3 dB;C波段的内导体非接触式同轴接头在3.5~4.2 GHz下实测|S_(11)|<-30 dB,通带内插入损耗小于0.2 dB。该改进型同轴接头设计方法为卫星通信系统的微波连接器的设计提供了重要的参考价值和新的研究思路。

非接触式摩擦纳米发电机的最新研究进展

目的 随着科学技术的快速发展,人们对可持续能源的需求不断增加。摩擦纳米发电机(TENG)利用各类微弱机械能实现自供电,有利于缓解这一需求。非接触式摩擦纳米发电机(NC-TENG)可以提高稳定性和使用寿命。总结NC-TENG的最新研究进展,为NC-TENG的结构设计、性能优化提供有益参考。方法 根据NC-TENG的器件结构与输出性能优化方法,介绍不同NC-TENG及其性能,重点综述其在智能包装领域的应用,并对未来的性能优化和应用工作进行展望。结果 基于不同的组装结构,通过介电常数调制、添加电荷捕获中间层等性能优化方案可以有效地避免静电放电问题,提高NC-TENG的电荷保留率。结论 NC-TENG相较于TENG,有着更高的稳定性和更长的使用寿命,在应对能源危机和推动新兴电子产品方面显示出巨大的潜力,预计在智能包装领域有着广泛的应用前景。

可调谐探针起振系统设计

为了兼顾非接触式原子力显微镜(noncontact atomic force microscope,NC-AFM)更高谐振频率探针的使用需求,并通过提高控制器精度进而提高NC-AFM分辨率,提出了一种基于探针-样品间原子作用力变化的全数字可调谐NC-AFM高分辨率探针起振系统。在Simulink环境下对探针起振系统的控制部分进行了设计,通过现场可编程门阵列(FPGA)实现了鉴相,滤波,锁频等功能;采用压电陶瓷片驱动探针振动,设计了操作便捷的探针座。将不同频率正弦信号提供给设计的起振系统进行功能性验证,实验结果表明,系统可以在20 kHz~50 MHz频率范围内跟踪探针谐振频率;最后使用起振系统成功使商用探针在谐振频率处振动,准确测出了探针的谐振频率及振动幅值,系统频率分辨率达到了0.1 Hz。

利用近红外吸收光谱特性实现酒精浓度的非接触式测量系统的设计

酒精浓度的非接触式测量是一种新型的测量方法。对一些特殊行业有着很大的帮助,比如酿酒业测量酒的酒精浓度,工业上生产工业酒精等。为了便于测量不能接触的酒精溶液,文中设计了一种基于近红外吸收光谱特性的酒精浓度测量系统,可以对不同浓度的酒精溶液进行非接触式连续测量。对于酒精来说,在1300~1350 nm的光谱段浓度定性反应非常明显,使用处于该波段的红外LED发光二极管,加上光电二极管、模数转换芯片、单片机和LCD屏幕组成该系统。通过使用该系统对不同浓度的酒精进行测量,利用最小二乘法找到酒精浓度和电压信号之间的函数关系式。这样就能通过测量电压值来反推出酒精浓度值。实验表明,在该红外波段下,采集到的电压值和酒精浓度之间有良好的二次函数关系,拟合优度达到了0.99946。测量结果显示,测量值和标准值之间的相关系数R为0.999911,平均绝对误差为0.64。与传统酒精计的0.5相差不大,重复测量和连续测量的方差分别为0.0044和0.0056,证明了该装置的稳定性和可靠性符合预期。而且通过优化电路和程序,选择更为精确的酒精计作为标准,可以使误差更小。该方案相比传统测量方法结构简单,速度更快,还可以进行连续测量。在现实生活中,制酒业、医疗行业和工业生产等行业都对于测量酒精浓度有着很高的需求。该装置可以在不损坏产品的情况下进行酒精浓度测量,它的连续检测能力对某些行业的批量生产有着很大的帮助。通过改良,可以实现自动化检测。除了企业生产,也可用于制造日常使用的便携式酒精浓度测量仪。

Flexible piezoelectret film sensor for noncontact mechanical signal capture by multiple transmission media

Mechanical signal capture without physical contact has emerged as a highly promising research field and attracted tremendous attention due to its prosperous applications in household medical care,lifestyle monitoring and remote operation,offering users high level of safety,convenience and comfort.Moreover,noncontact sensing is ideal to maximize the immersive user experience in the human–machine interaction(HMI),eliminating interference to human activities and mechanical fatigue to the sensor,simultaneously.Herein,we report a self-powered flexible sensor integrated with irradiation cross-linked polypropylene(IXPP)piezoelectret film for noncontact sensing,featuring multi-functions to detect mechanical signals transmitted through solid,liquid and gaseous media and would facilitate their versatile practical applications.The folded-structure configuration of the sensor facilitates the improvement of the noncontact sensing sensitivity.For solid media,such as the rectangular wooden stick used in this study,the sensor can detect mechanical stimulus exerted at a distance of 100 cm.A system detection sensitivity up to 57 pC/kPa with a low detection limit of 0.6 kPa is achieved at a noncontact distance of 10 cm.Even when partly or completely immersed in water,the sensor effectively traces movement signals of human bodies underwater,demonstrating great advantages for non-inductive aquatic fitness training monitoring.Furthermore,due to the low acoustic impedance of piezoelectret film,speech recognition through gaseous medium is also achieved.We further introduce application demonstrations of the developed film sensors to monitor exercise postures and physiological signals without direct contact between human body and the sensor,displaying great potential to be incorporated into future smart electronics.This study commendably expands the application scope of piezoelectret materials,which will have profound implications for exploring novel intelligent human–machine interactions.

Noncontact ultrasound sensing based on Mach-Zehnder homodyne interferometer for photoacoustic imaging

We present a novel noncontact ultrasound(US)and photoacoustic imaging(PAI)system,overcoming the limitations of traditional coupling media.Using a long coherent length laser,we employ a homodyne free-space Mach-Zehnder setup with zero-crossing triggering,achieving a noise equivalent pressure of 703 Pa at 5 MHz and a-6 dB bandwidth of 1 to8.54 MHz.We address the phase uncertainty inherent in the homodyne method.Scanning the noncontact US probe enables photoacoustic computed tomography(PACT).Phantom studies demonstrate imaging performance and system stability,underscoring the potential of our system for noncontact US sensing and PAI.