一种液位检测方法在流量标准装置上的应用

本文介绍了超声波壁外透射衰减式定点液位测量的原理,提出了非介入式定点液位测量方法在动态容积法流量标准装置上的应用方案。定点液位测量提高了流量标准装置的工作效率,能够使流量标准装置直接检定腐蚀性液体流量计,并且可以实现校准过程的自动化、数据的自动采集和自动化管理。     

新型智能外贴超声波液位开关在危化品储罐液位控制的应用

为了解决液位开关在危化品控制中的误报、漏报等问题,本公司开发了一种新型智能外贴超声波液位开关该智能液位开关通过外贴的超声发射接收装置向灌内发射超声波信号,通过对接收信号的分析与处理判断是否达到指定的液位位置,实现液位的监测。该液位开关由于其具有可靠性强、稳定性高、安装简单等特点被广泛应用于易燃、易爆、有毒、腐蚀性液体等危化品储罐的液位检测与控制当中。     

基于超声波技术的非接触液位开关

在工业生产中液位开关起到了重要作用。传统的液位开关一般为浮球式或连通器式,难以满足高压、强腐蚀性等特殊液体的测量要求。为此,文中设计了一种非接触液位开关。该装置从容器外侧壁向容器内发射超声波,通过检测容器侧壁超声波余振信号的强度,判断液体是否到达指定液位。该装置包括超声波发射模块、超声波接收模块、单片机控制模块、液晶显示模块、无线传输模块。实验表明,该装置不仅能够有效地实现非接触液位开关的功能,且可以通过无线传输实现远程监测。     

自校准超声波液位测量的研究

针对超声波液位测量常用方法的不足，提出了一种新型液位测量系统——自校准超声波液位测量系统，适用于各种物性液体及各种恶劣工况下的液位测量。详细地介绍了该测量系统的两种测量装置、测量原理、测量仪器及其硬件、软件结构。     

稳态转向时非满载罐式汽车侧翻稳定性的分析

由于非满载罐内液体货物的晃动 ,运输液体货物的罐式汽车与运输固体货物的汽车在弯道或变道行驶时 ,其侧翻稳定性将发生较大的变化。本文通过对罐内晃动液体质心位置的分析 ,建立了罐式汽车侧翻数学模型 ,研究了部分装载液体罐式汽车的稳态转向侧翻阈值 ,并简要介绍了导致罐式汽车侧翻的主要汽车因素 ,为进一步研究罐式汽车的侧翻特性和侧翻的检测及预防方法打下基础。     

基于串口控制的超声波液位检测系统研究

在许多工业生产系统中,需要对系统的液位或物料位进行监测,特别是对具有腐蚀性的液体液位的测量,论文提出了一种基于串口控制的超声波液位检测系统.利用单片机系统控制液位,非接触测量实现对工业系统中液位或物料位的检测,具有精度高、风险小、易控制等优点,具备很强的实用性.     

超声波壁外透射衰减式定点液位测量方法研究

分析了容器内部为气相介质和液相介质两种情况下容器壁中超声波余振信号的衰减特性，在此基础上提出了基于容器壁上超声波余振信号衰减检测原理的一种新的超声波容器定点液位检测的方法，并介绍了其原理和实施方案。该方法为非介入测量方式，探头只需附着于容器壁外，安装极为简单，且具有灵敏度高、可靠性好等优点，极适合于高压容器，腐蚀性液体容器的定点液位检测与报警。     

一种新型的接触式超声波液位报警器

介绍了一种新型的接触式超声波液位报警器。该报警器是基于超声波在液体和空气中传播时性能参数差别较大的原理设计的，详细介绍了其系统结构和工作原理。为保证可靠性和检验方便，系统设计了可靠性检验电路，对电路的原理和使用方法进行了充分说明。该报警器具有测试精度高、环境适应能力强、可靠性高等特点，已在舰船上得到实际应用。     

连通管式位移测量系统的液位振荡特性

针对动态测量时连通管式位移测量系统中的液体振荡会影响构筑物位移测量的精度,建立了三通道连通管模型,推导了连通管内液位振荡的微分方程,据此进行了仿真分析,得到了液位的振荡特性,并进行了验证试验。试验结果表明,连通管液位振荡模型能描述连通管内液体的振荡特性,只需对测量系统进行优化设计,就可有效地消除液位振荡。     

多层液体分析仪在氢氧化铝行业沉降槽的使用

本文主要介绍了多层液体分析仪在氢氧化铝行业沉降槽的使用。多层液体分析仪是通过采集沉降槽中各层液位的超声波声速、能量等参数,并用Liquid Smart专用软件做分析,检测出液体总高度和液体的分层高度的一款自动化智能液层高度分析仪。     

线性时变动力系统参数识别方法与试验分析

根据时变频率的定义由时变动力系统的响应计算瞬时频率,由自由衰减响应或希尔伯特阻尼谱识别瞬时阻尼特性。采用2层框架结构数值模型验证了识别方法的可行性,进而应用于12层短肢剪力墙结构振动台实验及识别模型结构在试验过程中动力性能的时变特性。将识别所得瞬时阻尼比代入有限元模型中计算结构响应,并与常值阻尼比及实测结果进行了对比。结果表明,采用时变阻尼比的计算结果更接近实测响应,文中方法可以反映结构的时变动力特性。     

基于超声波传感器的无线液位测量系统

针对诸多行业储液罐液位测量的特点和技术要求,设计了一种基于超声波传感器的无线液位测量系统.系统由液位检测模块、无线数传模块和上位机工作站组成.传感器将接收到的信号经数据处理后由无线数传模块送上位机工作站,工作站是由VC设计的一个数据处理平台,具有多路液位显示、超限报警、数据存储和打印等功能.     

基于检测状态模型的飞机结构件在线检测路径规划

针对飞机结构件在线检测路径规划中零件工艺模型伴随加工过程动态变化、检测工艺复杂的难点,提出了基于检测状态模型的飞机结构件在线检测路径规划方法。检测状态模型以特征为载体,以干涉特征和虚路径表达干涉规避、路径优化等知识和经验,并随着加工过程动态扩充。基于检测状态模型,按照检测操作级、检测特征级、特征自身级三级实现了在线检测路径规划。根据以上研究,基于CATIA V5开发的在线检测数据自动生成系统已在某大型航空企业中得到成功应用。     

Separated two-phase flow regime parameter measurement by a high speed ultrasonic pulse-echo system

In this work, a high speed ultrasonic multitransducer pulse-echo system using a four transducer method was used for the dynamic characterization of gas-liquid two-phase separated flow regimes. The ultrasonic system consists of an ultrasonic pulse signal generator, multiplexer, 10 MHz (0.64 cm) ultrasonic transducers, and a data acquisition system. Four transducers are mounted on a horizontal 2.1 cm inner diameter circular pipe. The system uses a pulse-echo method sampled every 0.5 ms for a 1 s duration. A peak detection algorithm (the C-scan mode) is developed to extract the location of the gas-liquid interface after signal processing. Using the measured instantaneous location of the gas/liquid interface, two-phase flow interfacial parameters in separated flow regimes are determined such as liquid level and void fraction for stratified wavy and annular flow. The shape of the gas-liquid interface and, hence, the instantaneous and cross-sectional averaged void fraction is also determined. The results show that the high speed ultrasonic pulse-echo system provides accurate results for the determination of the liquid level within +/-1.5%, and the time averaged liquid level measurements performed in the present work agree within +/-10% with the theoretical models. The results also show that the time averaged void fraction measurements for a stratified smooth flow, stratified wavy flow, and annular flow qualitatively agree with the theoretical predictions.     

Interaction of pulse ultrasonic signals with reflectors of different types

The results of experimental studies of the processes of interaction of pulse ultrasonic signals with artificial reflectors of different types are presented. To estimate nonstationary frequency characteristics of echo signals, it is proposed to use an algorithm for determining the instantaneous frequency that is based on the use of a wavelet transform characterized by increased noise immunity. It is shown that the instantaneous frequency of the reflected pulse signal may substantially differ from the rated frequency of a piezoelectric transducer for different types of reflectors. The frequency difference has a minimum value at a minimum curvature of the reflected-wave front. The obtained results must be considered during implementation of conventional methods of ultrasonic nondestructive testing because disregarding the effect of frequency deviation from the rated value may lead to a violation of the requirements of the acting standards for the tolerance for the operating frequency of a piezoelectric transducer. The difference of the instantaneous frequency from the rated frequency depends on the reflector type and can be used as an informative indicator of a flaw’s shape.     

Analysis on profile accuracy for ultrasonic machining of alumina ceramics

Ultrasonic machining (USM) is a mechanical material removal process which has great potential for machining hard and brittle materials such as ceramics, semiconductors, glasses, etc. The accuracy of the job profile generated by USM can be improved by optimal control of the process parameters. This paper presents the study on the influences of ultrasonic machining process parameters such as abrasive grit size, slurry concentration, power rating, tool feed rate and slurry flow rate on generated hexagonal hole profile. The angular deviations at corner angles, dimensional deviations across flat surfaces and dimensional deviation across corners of the hexagonal hole profile have been studied. Based on experimental results, the influences of abrasive grit size, slurry concentration, power rating and tool feed rate were analysed. From the analysis of parametric influences based on various test results, the best parametric combination was found as grit number of 600, slurry concentration of 30 %, power rating of 50 % and feed rate of 1.08 mm/min for achieving better profile accuracy during machining of Al₂O₃ ceramics. The experimental investigations carried out for determining the influence of USM process parameters will provide effective guideline to select parametric settings for achieving desired job profile accuracy on non-circular holes during ultrasonic drilling of alumina.     

Rotary ultrasonic machining: effects of tool natural frequency on ultrasonic vibration amplitude

Rotary ultrasonic machining (RUM) is a hybrid machining process that combines the material removal mechanisms of grinding and ultrasonic machining. RUM has been applied to hole-making for a wide range of materials. It is known that ultrasonic vibration amplitude has significant effects on cutting force, torque, and surface finish in RUM. One experimental observation that has been reported in the literature multiple times states that different tools show different vibration amplitudes on the same ultrasonic power level. However, no analyses can be found in the literature to explain this observation. The existence of this knowledge gap makes it difficult to explain some experimentally obtained trends or to conduct more realistic physics-based modeling work. The objectives of this research are to understand the effects of tool natural frequency on ultrasonic vibration amplitude in RUM, to provide an explanation to the observation and verification of measurement methods, and also to guide tool design and selection in RUM. Ultrasonic vibration amplitudes of tools are measured by three methods and compared. It is found that tool natural frequency significantly affects ultrasonic vibration amplitude. The tool with its natural frequency closest to that of the ultrasonic power supply (20?kHz) generates the highest ultrasonic vibration amplitude on every ultrasonic power level tested.     

Chatter vibration surveillance by the optimal-linear spindle speed control

The paper concerns self-excited chatter vibration during high speed slender ball-end milling. Non-stationary cutting process, with inclusion of various approaches towards dynamic characteristics of the process, is described. Dynamic analysis of the milling process is performed and dynamics of controlled closed loop system with time-delay is presented. In order to reduce vibration level, instantaneous change in the spindle speed appears as a control command, and thus—the method of vibration surveillance by the spindle speed optimal-linear control is developed. Presented cutting models have been applied for the proposed method and procedure of the chatter vibration surveillance with a use of variable spindle speed has been developed. Computer simulations are performed for selected cases of ball-end milling at constant and variable spindle speed. The results of them are successfully confirmed by experimental investigations on the Alcera Gambin 120CR milling machine equipped with the S2M high speed electrospindle.     

Experimental investigation on the effects of thermomechanical loading on the vibrational stability during rotary ultrasonic machining

Ultrasonic vibration is assumed to be stable or unchangeable during the process of rotary ultrasonic machining (RUM) on brittle materials, neglecting the effects of different processing parameters. However, no experimental evidence has been reported to validate this assumption. In this study, the effect of thermomechanical load on the stability of ultrasonic amplitude during RUM was investigated by theoretical analysis and experimental procedures on quartz glass and sapphire. It was shown that the instability of ultrasonic amplitude during the machining process is mainly attributed to variation of resonant frequency under the implementation of thermomechanical load. The thermal effects of ultrasonic vibration decrease the resonant frequency of the ultrasonic machine, while mechanical loading during the machining process increases the resonant frequency. Furthermore, a higher feed rate or a harder material leads to a higher resonant frequency change. The variation of ultrasonic power can be used to review the validity of difference-neglected assumption when different values of processing variables, materials, or even machine tools are used during modeling. The results of this study should be well considered for future references when designing an ultrasonic machine.     

功率超声系统负载的检测及模糊控制

功率超声医疗设备在治疗的过程中,为了取得良好的超声乳化效果,要求振动系统在不同的负载下都具有较大的输出振幅,这就要求振动系统在不同的负载下都工作在匹配状态下.文章首先分析了纵向复合棒大功率换能器加接变幅杆和刀具的振动系统的等效机电模型,然后根据等效机电模型分析了功率超声振动系统动态阻抗匹配的基本原理.同时针对功率超声系统的工作特点设计了一种动态负载在线检测方法,得到反映负载状态及其变化趋势的参数,并根据识别出的动态负载确定出模糊控制器的输入输出参数.最后给出了一种实用的模糊控制算法进行振动系统的动态阻抗匹配.实验结果表明,利用模糊控制器进行动态阻抗匹配能保证振动系统在变负载的情况下仍然获取较高的电功率和较好的超声乳化效果.