The Experts below are selected from a list of 3246072 Experts worldwide ranked by ideXlab platform
Gijsbertus J.m. Krijnen - One of the best experts on this subject based on the ideXlab platform.
-
a 2d acoustic particle velocity sensor with perfectly orthogonal sensitivity directions
Sensors and Actuators A-physical, 2016Co-Authors: O. Pjetri, Theodorus S J Lammerink, Gijsbertus J.m. KrijnenAbstract:A two-dimensional acoustic particle velocity sensor as well as the required interfacing electronics have been designed and realized. The novel crossed-wire sensor structure provides a direct two- dimensional measurement and, contrary to current 2D particle velocity sensors, the sensitive directions are exactly orthogonal to each other due to the inherent symmetry of the sensor. This new design of size 1.0 mm × 2.5 mm × 0.5 mm dissipates only half the power required by current one-dimensional particle velocity sensors, has comparable bandwidth at modest 15 dB higher selfnoise. Furthermore, it requires no directivity calibration, which was difficult to achieve in previous designs. The devices are relatively easy to fabricate, smaller and mechanically more robust than existing parallel-wire particle velocity sensors, resulting in better resistance against harsh fabrication steps and, consequently, higher fabrication yield.
Volkan Isler - One of the best experts on this subject based on the ideXlab platform.
-
stochastic event capture using mobile sensors subject to a quality metric
ACM IEEE International Conference on Mobile Computing and Networking, 2006Co-Authors: Nabhendra Bisnik, Alhussein A Abouzeid, Volkan IslerAbstract:Mobile sensors cover more area over a period of time than the same number of stationary sensors. However, the quality of coverage achieved by mobile sensors depends on the velocity, mobility pattern, number of mobile sensors deployed and the dynamics of the phenomenon being sensed. The gains attained by mobile sensors over static sensors and the optimal motion strategies for mobile sensors are not well understood. In this paper we consider the problem of event capture using mobile sensors. The events of interest arrive at certain points in the sensor field and fade away according to arrival and departure time distributions. An event is said to be captured if it is sensed by one of the mobile sensors before it fades away. For this scenario we analyze how the quality of coverage scales with the velocity, path and number of mobile sensors. We characterize the cases where the deployment of mobile sensors has no advantage over static sensors and find the optimal velocity pattern that a mobile sensor should adopt.We also present algorithms for two motion planning problems: (i) for a single sensor, what is the minimum speed and sensor trajectory required to satisfy a bound on event loss probability and (ii) for sensors with fixed speed, what is the minimum number of sensors required to satisfy a bound on event loss probability. When events occur only along a line or a closed curve our algorithms return optimal velocity for the minimum velocity problem. For the minimum sensor problem, the number of sensors used is within a factor two of the optimal solution. For the case where the events occur at arbitrary points on a plane we present heuristic algorithms for the above motion planning problems and bound their performance with respect to the optimal. The results of this paper have wide range of applications in areas like surveillance, wildlife monitoring, hybrid sensor networks and under-water sensor networks.
Latasha Solomon - One of the best experts on this subject based on the ideXlab platform.
-
transient detection via acoustic particle velocity multi mission sensor
Journal of the Acoustical Society of America, 2014Co-Authors: Latasha SolomonAbstract:In this research, we compare the direction of arrival (DOA) accuracy of a micro-electro-mechanical systems (MEMS) based acoustic particle velocity sensor developed by Microflown Technologies with that of a collocated, 1-m tetrahedral array. When deployed as an unattended sensor system, the Acoustic Multi-Mission Sensor (AMMS) greatly facilitates hardware set-up and periodic maintenance. An array of microphones is now replaced by a single sensor, saving in overall system cost, size, weight, and power usage. The single sensor has the capability to measure both the (scalar) sound pressure and the (vector) acoustic particle velocity, thus providing DOA estimates. This research will explore performance and determine limitation of the two sensors in complex environments as well as open fields for detection of both small arms fire (SAF) and rocket propelled grenades (RPGs).
-
transient detection via micro electro mechanical systems based acoustic particle velocity sensor
166th Meeting of the Acoustical Society of America, 2014Co-Authors: Latasha SolomonAbstract:In this research, we compare the direction of arrival (DOA) accuracy of a micro-electro-mechanical systems (MEMS) based acoustic particle velocity sensor developed by Microflown Technologies with that of a collocated, 1-m tetrahedral array. When deployed as an unattended sensor system, the Acoustic Multi-Mission Sensor (AMMS) greatly facilitates hardware set-up and periodic maintenance. An array of microphones is now replaced by a single sensor, saving in overall system cost, size, weight, and power usage. The single sensor has the capability to measure both the (scalar) sound pressure and the (vector) acoustic particle velocity, thus providing DOA estimates. This research will explore performance and determine limitation of the two sensors in complex environments as well as open fields for detection of both small arms fire (SAF) and rocket propelled grenades (RPGs).
-
transient detection via micro electro mechanical systems based acoustic particle velocity sensor
166th Meeting of the Acoustical Society of America, 2014Co-Authors: Latasha SolomonAbstract:In this research, we compare the direction of arrival (DOA) accuracy of a micro-electro-mechanical systems (MEMS) based acoustic particle velocity sensor developed by Microflown Technologies with that of a collocated, 1-m tetrahedral array. When deployed as an unattended sensor system, the Acoustic Multi-Mission Sensor (AMMS) greatly facilitates hardware set-up and periodic maintenance. An array of microphones is now replaced by a single sensor, saving in overall system cost, size, weight, and power usage. The single sensor has the capability to measure both the (scalar) sound pressure and the (vector) acoustic particle velocity, thus providing DOA estimates. This research will explore performance and determine limitation of the two sensors in complex environments as well as open fields for detection of both small arms fire (SAF) and rocket propelled grenades (RPGs).
Jurgen Czarske - One of the best experts on this subject based on the ideXlab platform.
-
determination of the axial velocity component by a laser doppler velocity profile sensor
Journal of The Optical Society of America A-optics Image Science and Vision, 2006Co-Authors: Lars Buttner, Jurgen CzarskeAbstract:We report about the determination of the axial velocity component by a laser Doppler velocity profile sensor that is based on two superposed fanlike interference fringe systems. Evaluation of the ratio of the Doppler frequencies obtained from each fringe system yields the lateral velocity component and the axial position inside the fringe system. Inclined particle trajectories result in chirped burst signals, where the change of the Doppler frequency in one burst signal is directly related to the axial velocity component. For one single tracer particle it is possible to determine (i) the lateral velocity component, (ii) the axial velocity component including the direction, and (iii) the axial position of the tracer trajectory. In this paper we present the measurement principle and report about results from simulation and experiments. An uncertainty of the axial velocity component of about 3% and a spatial resolution in the micrometer range were achieved. Possible applications of the sensor lie in three-component velocity measurements of flow fields where only one optical access is available.
-
laser doppler velocity profile sensor with submicrometer spatial resolution that employs fiber optics and a diffractive lens
Applied Optics, 2005Co-Authors: Lars Buttner, Jurgen Czarske, Hans KnuppertzAbstract:We report a novel laser-Doppler velocity profile sensor for microfluidic and nanofluidic applications and turbulence research. The sensor’s design is based on wavelength-division multiplexing. The high dispersion of a diffractive lens is used to generate a measurement volume with convergent and divergent interference fringes by means of two laser wavelengths. Evaluation of the scattered light from tracers allows velocity gradients to be measured in flows with submicrometer spatial resolution inside a measurement volume of 700-µm length. Using diffraction optics and fiber optics, we achieved a miniaturized and robust velocity profile sensor for highly resolved velocity measurements.
-
boundary layer velocity measurements by a laser doppler profile sensor with micrometre spatial resolution
Measurement Science and Technology, 2002Co-Authors: Jurgen Czarske, Lars Buttner, Thorsten Razik, H MullerAbstract:We have developed a differential laser Doppler profile sensor for distributed one-component velocity measurements with high spatial resolution. Two Doppler frequencies are measured simultaneously in order to determine the position as well as the velocity of individual tracer particles passing through the measurement volume. In the centre of the measurement volume the obtained uncertainty of the position is about 1.6 µm. The profile measurement has the advantage that no mechanical scanning is needed to obtain flow velocity profiles over a length of 5 mm. The profile sensor thus provides a tool for highly resolved instantaneous measurements of shear flows, which have strong velocity gradients.
A A Isler - One of the best experts on this subject based on the ideXlab platform.
-
stochastic event capture using mobile sensors subject to a quality metric
IEEE Transactions on Robotics, 2007Co-Authors: M Bisnik, Alhussein A Abouzeid, A A IslerAbstract:Mobile sensors cover more area over a fixed period of time than do the same number of stationary sensors. However, the quality of coverage (QoC) achieved by mobile sensors depends on the velocity, mobility pattern, number of mobile sensors deployed, and the dynamics of the phenomenon being sensed. The gains attained by mobile sensors over static sensors and the optimal motion strategies for mobile sensors are not well understood. In this paper, we consider the following event capture problem: the events of interest arrive at certain points in the sensor field and disappear according to known arrival and departure time distributions. An event is said to be captured if it is sensed by one of the mobile sensors before it fades away. We analyze how the QoC scales with velocity, path, and number of mobile sensors. We characterize cases where the deployment of mobile sensors has no advantage over static sensors, and find the optimal velocity pattern that a mobile sensor should adopt. We also present algorithms for two motion planning problems: 1) for a single sensor, what is the sensor trajectory and the minimum speed required to satisfy a bound on the event loss probability and 2) for sensors with fixed speed, what is the minimum number of sensors required to satisfy a bound on the event loss probability. When the robots are restricted to move along a line or a closed curve, our algorithms return the optimal velocity for the minimum velocity problem. For the minimum sensor problem, the number of sensors used is within a factor of 2 of the optimal solution. For the case where the events occur at arbitrary points on a plane, we present heuristic algorithms for the aforementioned motion planning problems and bound their performance with respect to the optimal.
