Wireless Passive High-Temperature Sensor Readout System for Rotational-Speed Measurement

Rotational-speed measurement in harsh environments is an important topic. However, the high rotation results in rapid frequency variations in the signals of a sensor and changes in physical properties under extreme thermal circumstances cause significant difficulties in reading signals. To address this problem, we adopt wireless passive measurement methods to design a special characteristic signal circuit module that achieves precise measurement of rotational speed at high temperatures. The sensor and the readout system include a variable frequency source, a readout antenna, and a radio frequency demodulation circuit. Herein, a demodulation detector of the signal conversion circuit is designed and used in the envelope detection module of the single sideband demodulation method. In addition, a conversion circuit test platform for high-temperature environment sensor signal is developed. From the testing, the output signal demodulation of the sensor was observed under a maximum temperature of 700°C with error less than 0.12%. The new sensor and measurement method do not require physical leads and achieve wireless noncontact accurate measurement of rotational speed at high temperature.

Investigation of an Active Measurement Method to Detect Inertial Cavitation and the Presence of Potential Drug Carriers

Drug carriers, such as nanoparticles, are capable of releasing pharmaceutically active ingredients, which can be initiated by focused ultrasound via the effect of inertial cavitation. This effect of inertial cavitation is often verified by passive measurement methods that rely on the analysis of emitted acoustic signals caused by the implosion of bubbles. However, a major issue of such methods is their inability to detect the presence of potential drugs in human vessels, complicating the implementation of a closed loop control for future medical therapies. Therefore, this contribution introduces an active measurement method to determine both inertial cavitation and the presence of potential drug carriers in a tissue mimicking phantom

Passive Measurement of Three Optical Beacon Coordinates Using a Simultaneous Method

Among other things, passive methods based on the processing of images of feature points or beacons captured by an image sensor are used to measure the relative position of objects. At least two cameras usually have to be used to obtain the required information, or the cameras are combined with other sensors working on different physical principles. This paper describes the principle of passively measuring three position coordinates of an optical beacon using a simultaneous method and presents the results of corresponding experimental tests. The beacon is represented by an artificial geometric structure, consisting of several semiconductor light sources. The sources are suitably arranged to allow, all from one camera, passive measurement of the distance, two position angles, the azimuth, and the beacon elevation. The mathematical model of this method consists of working equations containing measured coordinates, geometric parameters of the beacon, and geometric parameters of the beacon image captured by the camera. All the results of these experimental tests are presented.

Unique Determination of the Shape of a Scattering Screen from a Passive Measurement

We consider the problem of fixed frequency acoustic scattering from a sound-soft flat screen. More precisely, the obstacle is restricted to a two-dimensional plane and interacting with an arbitrary incident wave, it scatters acoustic waves to three-dimensional space. The model is particularly relevant in the study and design of reflecting sonars and antennas, cases where one cannot assume that the incident wave is a plane wave. Our main result is that given the plane where the screen is located, the far-field pattern produced by any single arbitrary incident wave determines the exact shape of the screen, as long as it is not antisymmetric with respect to the plane. This holds even for screens whose shape is an arbitrary simply connected smooth domain. This is in contrast to earlier work where the incident wave had to be a plane wave, or more recent work where only polygonal scatterers are determined.

Coverage Error in Data Collection Combining Mobile Surveys With Passive Measurement Using Apps: Data From a German National Survey

Researchers are combining self-reports from mobile surveys with passive data collection using sensors and apps on smartphones increasingly more often. While smartphones are commonly used in some groups of individuals, smartphone penetration is significantly lower in other groups. In addition, different operating systems (OSs) limit how mobile data can be collected passively. These limitations cause concern about coverage error in studies targeting the general population. Based on data from the Panel Study Labour Market and Social Security (PASS), an annual probability-based mixed-mode survey on the labor market and poverty in Germany, we find that smartphone ownership and ownership of smartphones with specific OSs are correlated with a number of sociodemographic and substantive variables. The use of weighting techniques based on sociodemographic information available for both owners and nonowners reduces these differences but does not eliminate them.