Minimum Detectable Distance Research Articles

Ultra-sensitive tactile force/proximity sensor based on monolithically integrated microcantilever

This paper reports a monolithically integrated tactile force and proximity sensor composed of a piezoresistive microcantilever array and a signal processing circuit. Both the microcantilever array and the signal processing circuit were fabricated on a single-crystalline silicon device layer of a silicon-on-insulator (SOI) wafer with a partially depleted (PD) SOI CMOS (complementary metal oxide semiconductor) technology followed by three micromachining processes. A dual-detection sensor of tactile force and proximity was realized by packaging the microcantilever with a polydimethylsiloxane (PDMS) elastomer on a flexible printed circuit board. A force resolution of 68 μN, a force sensitivity of 14.6 mV/N and a minimum detectable displacement of 0.1 μm were obtained in force mode. A minimum detectable distance of 2.5 mm and 2.6 mm were achieved for objects and human proximity detections in photoelectric and thermomechanical modes, respectively. By using the ultra-sensitive force sensor, wrist radial artery pulse, fingertips pulse, breath and throat vibration of human body were collected accurately. These results prove that the integrated microcantilever can achieve both proximity and tactile sensing detections simultaneously with ultra-sensitivity.

128-channel optical phased array with large field of view and low main-lobe attenuation

In this paper, a 128-channel non-uniform optical phased array is proposed. The antenna is based on a silicon nitride waveguide with a large cross-sectional area (3 μm × 1.2 μm) and a silicon nitride grating with a small diffraction window (grating width of 200 nm), enabling high optical power transmission and a wide 1 dB field of view. As a result, the designed sparse optical phased array achieves less than 1 dB of main lobe attenuation over a 94° field of view. Within this field of view, the main lobe will not fall below 80% of the maximum main lobe. This allows the minimum detection distance to still be about 89% of the maximum detection distance without increasing the input power. In this field of view, the maximum side-lobe suppression of the designed sparse optical phased array is 13.4 dB, and the minimum side-lobe suppression is higher than 11.9 dB. This is useful for simultaneously achieving a large field of view, low main lobe attenuation, stable side-lobe suppression, and long detection distance.

직선형 파동유도관에서 벽면 쐐기의 길이에 따른 초음파 전파

This study focuses on the ultrasonic propagation along the wedge length of the wall in a straight waveguide designed to reduce the minimum detection distance of an ultrasonic sensor for distance measurement. Wedges are created on the waveguide wall to avoid ultrasound interference caused by reflection on a smooth wall, and the wedge dimensions must be chosen carefully. The magnitude of the ultrasonic signal was evaluated according to the wedge length in terms of the ratio of the target reflection to the exit reflection while maintaining the wedge angle selected in the previous study. The propagation of ultrasonic waves was studied using finite element analysis. The wedge length that maximizes the magnitude of the ultrasonic signal was found to be similar to the wavelength. It was possible to reduce unwanted reflection and increase target reflection by adjusting the waveguide wall wedge length.

나선형 파동유도관 결합을 통한 초음파센서의 탐지범위 개선

This paper presents a method to improve the detectable range of an ultrasonic sensor for distance measurements by coupling the sensor with a helical waveguide. In particular, this study aimed to decrease the effective length of circularly curved waveguides, in addition to reducing the minimum and maintaining the maximum detectable distances. To this end, finite element analyses were used to predict the ultrasound propagation in a waveguide with a uniform circular cross-section along the spiral path. Two types of cross-sectional sizes were compared: one with a diameter identical to that of the sensor face and another with a diameter twice this value. Furthermore, experiments were performed with fabricated prototypes to evaluate the detectable range by measuring the minimum and maximum detectable distances. Notably, by coupling the helical waveguide with the ultrasonic sensor, the minimum detectable distance was reduced to 1/3 times that for a sensor without the waveguide, while the maximum detectable distance was maintained. Moreover, the effective length of the helical waveguide was decreased, as compared with that of linear or circularly curved waveguides.

초음파센서의 최소탐지거리 단축용 원호형 파동유도관

This study proposes a method to reduce the minimum detectable distance of an ultrasonic sensor by combining a circularly curved waveguide. The minimum detectable distance of ultrasonic sensors for distance measurement is limited because of the blind zone time caused by residual vibration of the sensor plate. The purpose of this study is to design a variety of waveguides and evaluate their performance of shortening the minimum detectable distance. Ultrasonic wave propagation in the designed waveguides was analyzed by finite elements and tested by fabricated prototypes. The performance was evaluated by comparing the sound pressure magnitude of the received signal. The received signal of the circularly curved waveguide was greater than that of the linear waveguide. Using a circularly curved waveguide with constant curvature, we achieved the shortening effect of the minimum detectable distance in addition to reducing the effective length of the waveguide.

The IMPLEMENTATION OF SYSTEM DOOR ACCES USING FACE RECOGNITION AND FINGER PRINT FOR MUNITIONS WAREHOUSE WITH A BASE HAAR CASSCADE

Abstract: Technology in the military world has been growing with the existence of technological innovations that are used to secure munitions warehouses. This is done to reduce the negligence of the munitions warehouse guard personnel if they lose the key from the munitions warehouse it can be monitored in real-time to find out who is around the munitions warehouse door. Thus, face recognition and fingerprint technology were created as a system for securing munitions warehouses, as well as the function is to be a CCTV. So, they can be monitored in real-time. This research method uses an experimental method to obtain quantitative data to prove the hypothesis data that use the Haar Cascade. The results of this study indicate that this security system has a very important role to limit access to and from the munitions warehouse and reduce the occurrence of theft or misuse of munitions. In the tests carried out, the minimum detection distance was 20 cm and the maximum distance that was able to detect was 110 cm. this is influenced by the focus of the camera and testing of the intensity of light in the morning, afternoon, evening, and night can be detected except detection at night without light and must use a fingerprint.

Assessing the effect of pedestrian deceleration on pedestrian autonomous emergency braking systems

The aim of the manuscript is to access whether the Rate of Collision Avoidance (RCA) will be improved by considering the pedestrian deceleration in the Pedestrian Autonomous Emergency Braking Systems (AEB-P). A vehicle braking method by considering the pedestrian deceleration was proposed firstly, and then through the Monte Carlo optimization algorithm optimal combinations of 7 input parameters were obtained by applying the method to 124 actual collisions, finally the single factor analysis method was used to explore the effects of each parameter on the RCA. Through observation from actual collisions, the interval of pedestrian deceleration was [0.1, 8.2]m/s2 with a median value of 4.2 m/s2 in an emergency. The optimal average value of the detection angle, the minimum detection distance, the lateral trigger distance, the pedestrian warning trigger distance, the lag time, the pedestrian deceleration and its reaction time is 60°, 25 m, 3.5 m, 0 m, 0 s, −8 m/s2 and 0 s, respectively. The maximum RCA = 84.68% was obtained based on optimal combinations. All analyses consistently found that the RCA increases as pedestrian deceleration increases. Results shown that we can consider pedestrian deceleration in the AEB-P to improve the performance of the system and subsequently improve the RCA.

초음파 수위계의 최소 탐지거리 단축을 위한 파동유도관

This paper describes a method to shorten the minimum detectable distance of an ultrasonic sensor in a liquid-level meter. The minimum detectable distance, which is limited by the number of ultrasonic transmission pulses and the ringing of the vibration plates in the sensor, needs to be shortened by an appropriate method. The purpose of this research is to improve the proximal measurement capability by combining the ultrasonic sensor for a liquid-level meter with a waveguide. Flat- and wedged-wall-type waveguides were designed and finite-element analysis was performed for ultrasound transmission and reception. Experiments were conducted for the distance and water level measurements by using the ultrasonic sensor combined with a waveguide. The results of the finite-element analysis and experiments showed that the wedged-wall-type waveguide produced reasonable measurements of the distance in the proximal range. We confirmed the improvement of the proximal-measurement capability of an ultrasonic level meter, thus shortening the minimum detectable distance by combination with a waveguide.

차량용 초음파 센서에서 파동유도관에 의한 최소 탐지거리 단축

In this study, a method of shortening the minimum detectable distance of an ultrasonic sensor for the distance measurement of automobiles was developed. It is necessary to overcome the limitations of the minimum detectable distance, which is induced by the residual vibration of an elastic disc in an ultrasonic sensor. The purpose of this study is to design a waveguide to shorten the minimum detectable distance and to improve the performance of proximal measurement by coupling the waveguide with an ultrasonic sensor. We simulated the ultrasound propagation in the designed waveguide through finite element analysis. The analytical results showed clear signals of transmitted and received ultrasound in a wedged-wall waveguide instead of a flat-wall waveguide. Experimental tests were performed to verify the analytical results. The waveguides of the flat and wedged walls were fabricated using a 3D printer and applied during the experiments. The results showed that the ultrasonic sensor coupled with the wedged-wall waveguide measured the proximal distance reasonably.

Reducing the minimum range of a RGB-depth sensor to aid navigation in visually impaired individuals

The introduction of RGB-depth (RGB-D) sensors harbors a revolutionary power in the field of navigational assistance for the visually impaired. However, RGB-D sensors are limited by a minimum detectable distance of about 800mm. This paper proposes an effective approach to decrease the minimum range for navigational assistance based on a RGB-D sensor of RealSense R200. A large-scale stereo matching between two infrared (IR) images and a cross-modal stereo matching between one IR image and RGB image are incorporated for short-range depth acquisition. The minimum range reduction is critical not only for avoiding obstacles up close, but also in the enhancement of traversability awareness. Overall, the minimum detectable distance of RealSense is reduced from 650mm to 60mm with qualified accuracy. A traversable line is created to give feedback to visually impaired individuals through stereo sound. The approach is proved to have usefulness and reliability by a comprehensive set of experiments and field tests in real-world scenarios involving real visually impaired participants.

Acoustic Detection of a Fixed-Wing UAV

The following paper presents results obtained from experiments conducted to investigate the viability of acoustic sensing to form the basis of a non-cooperative aircraft collision avoidance system. An unmanned aerial vehicle (UAV) fitted with two microphones was flown in the vicinity of another airborne UAV to determine the maximum distance at which the intruding aircraft could be detected. A two-dimensional analytical model to approximate the minimum detection distance required to facilitate an avoidance maneuver for a given spatial configuration is presented. A method to increase detection distances by exploiting the harmonic nature of acoustic signals generated by propeller-driven aircraft is also presented. The method significantly increases the detection distances compared to the commonly used incoherent spectral mean. It was found that a small gasoline-powered UAV could be detected at distances up to 678 m, which is more than double the minimum required to avoid a head-on collision.

A Method on the Improvement of the Minimum Detection Distance of the Remote Measurement Level Meter

A Method on the Improvement of the Minimum Detection Distance of the Remote Measurement Level Meter

Quantitative analysis of the angiogenic microvasculature in tumor using multiple scattering and dual-frequency transducers

The objective is to characterize angiogenic networks using contrast-enhanced multiple scattering. The methods relies on the measurement of the diffusion constant from the time evolution of the incoherent backscattered intensity. Dual-frequency arrays allow to emit a pulse at a frequency close to resonance frequency of microbubbles, and to receive the backscattered echoes at higher harmonics, resulting in better contrast-to-tissue ratio compared to single frequency transducers. At 8 MHz, we demonstrated that the diffusion constant enables the quantification of the vascular density and anisotropy in tumor-related vasculature in rat models in vivo. We show here that the results could be further improved using a dual-frequency approach, using two linear arrays with different central frequencies (7 MHz/18 MHz) and using a custom made dual frequency transducer (3 MHz/15 MHz). The minimum detectable distance between two vessel-mimicking cellulose tubes filled with contrast agents was measured via the diffusion constant. The dual-frequency approach drastically reduced the smallest detectable distance between tubes, which was found to be 25µm using a single frequency, 20µm using two linear arrays and 10µm using the custom dual-frequency array, respectively. These results show that measuring the diffusion constant with a dual frequency array can enable the quantification of vessel density with high accuracy

Research on the performance of multifunctional distributed optical fiber sensing system based on the combination of Brillouin optical time-domain analysis and phase-sensitive optical time-domain reflectometer

There are many similarities between Brillouin optical time-domain analysis and phase-sensitive optical time-domain reflectometer in system topological structure. A multifunctional distributed optical fiber sensing system based on their similarities and the combination of their topological structure is presented. The system can monitor strain and temperature, as well as detect and locate the intrusions or disturbances along the sensing fiber. Suppose that X is the width of the optical pulse incident into the sensing fiber with the unit of nanosecond and Y is the minimum detectable distance with the unit of meter between two intrusions that are being detected simultaneously. The experiment results show that y changes linearly with x according to the equation: y=0.103x−0.452. By optimizing device parameters of the system, strain measurement accuracy of 3.17 μϵ and the temperature measurement accuracy of 0.45°C have been realized when the optical pulse width is 30 ns. On the other hand, two intrusions have been detected and located simultaneously with this multifunctional system. The results show that the pulse width and the minimum distance between two intrusions (Lmin) have a linear relationship. The theoretical analyses and the experiment results show it is applicable to use this multifunctional system for strain and temperature monitoring, and intrusion detecting.

Interceptor and Phantom Trials of EDNS at UPMC

University of Pittsburgh Medical Center (UPMC) installed an Emergency Department Notification System (EDNS) in one of its hospitals. The system, manufactured by Thermo Fisher Scientific (Thermo Fisher Scientific, Inc., 81 Wyman Street, Waltham, MA 02454), consists of four NaI(Tl) scintillation detectors, a 2.5 L PVT gamma counter, a 512 channels multi-channel analyzer, a system controller, and a database-monitoring server. We evaluated a portable Interceptor Interceptor™ hand-held detector (Thermo Fisher Scientific, Inc., 81 Wyman Street, Waltham, MA 02454) as part of the system for potential ambulancebased early detection and warning unit. We present the minimum detectable activity, distance, and isotope identification success rates along with the change in detector response to various radioisotope sources placed in a Rando® humanoid phantom. (The Phantom Laboratory. P.O. Box 511, Salem, NY 12865-0511 USA). The present paper reports these results.

New model for gain control of signal intensity to object distance in echolocating bats

Echolocating bats emit ultrasonic calls and listen for the returning echoes to orient and localize prey in darkness. The emitted source level, SL (estimated signal intensity 10 cm from the mouth), is adjusted dynamically from call to call in response to sensory feedback as bats approach objects. A logarithmic relationship of SL=20 log(10)(x), i.e. 6 dB output reduction per halving of distance, x, has been proposed as a model for the relationship between emitted intensity and object distance, not only for bats but also for echolocating toothed whales. This logarithmic model suggests that the approaching echolocator maintains a constant intensity impinging upon the object, but it also implies ever-increasing source levels with distance, a physical and biological impossibility. We developed a new model for intensity compensation with an exponential rise to the maximum source level: SL=SL(max)-ae(-)(bx). In addition to providing a method for estimating maximum output, the new model also offers a tool for estimating a minimum detection distance where intensity compensation starts. We tested the new exponential model against the 'conventional' logarithmic model on data from five bat species. The new model performed better in 77% of the trials and as good as the conventional model in the rest (23%). We found much steeper rates of compensation when fitting the model to individual rather than pooled data, with slopes often steeper than -20 dB per halving of distance. This emphasizes the importance of analyzing individual events. The results are discussed in light of habitat constraints and the interaction between bats and their eared prey.

Experimental verification of measurement principle in standing wave radar capable of measuring distances down to zero meters

AbstractIn general, it is difficult to measure short distances by radar, which has a minimum detection distance of several meters. The standing wave radar proposed by the present authors has a minimum detection distance of about 2 m when the frequency bandwidth is 76 MHz. A solution to reduce the minimum detection distance is to increase the frequency bandwidth. This is not realistic due to limits imposed by radio regulations. The authors have proposed a method with measurable distances down to 0 m without enlarging the bandwidth and have presented the configuration and the measurement principle. The measurement principle has been verified by numerical simulation. In the present paper, the measurement principle is experimentally verified by using an actual standing wave radar and the realizability of a standing wave radar with measurement capability down to 0 m is confirmed. It is shown that the distance to the target at locations closer than the minimum detection distance of 2 m (0.14, 0.3, 0.5, and 1 m) can be measured with an error of several centimeters for a frequency bandwidth of 76 MHz at 24 GHz. For distances less than 0.14 m, the target could not be placed closer than 0.14 m due to positional interference of the target and the antenna in the present experimental environment so that physical confirmation was not possible. However, at the confirmed distance, the range spectrum predicted from the theory is obtained. Hence, it is considered possible to make measurements without special restrictions. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(9): 25– 34, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20375

ULTRASONIC IMAGING SYSTEM USING A 2D ENVELOPE BEAMFORMING TECHNIQUE: IN-HOMOGENEITIES LOCATION

An algorithm has been developed to implement synthetic aperture focusing technique for B-scan. This is made at a several transmitter/receiver locations to form a map of ultrasonic reflectivity on the insonified region, considering the path travelled by the ultrasonic pulse from the transducer to the target and back again. To reconstruct the image, a time domain beam-former is applied to the envelope of the detected signals. This method minimizes the side-lobe amplitude and the restriction of λ/2 distance between two adjacent transducer positions can be neglected without loosing image resolution. The present work is focused on the location of the in-homogeneities, caused by the presence of a phantom immersed in a water tank. The results are presented when the distance between two adjacent transducer positions are varied from 0.5λ to 2.5λ showing that the longitudinal resolution is not affected but the lateral resolution becomes poorer when the distance is about 2λ. The error in the longitudinal location of in-homogeneities is within the minimum detectable distance of the system, while the lateral location error is increased when the distance between any two adjacent transducer positions is larger than 1.5λ.

Basic principles of microscope objectives.

Microscope objectives are perhaps the most important components of an optical microscope because they are responsible for primary image formation and play a central role in determining the quality of images that the microscope is capable of producing. Objectives are also instrumental in determining the magnification of a particular specimen and the resolution under which fine specimen detail can be observed in the microscope. The objective is the most difficult component of an optical microscope to design and assemble and is the first component that light encounters as it proceeds from the specimen to the image plane. Objectives derive their name from the fact that they are, by proximity, the closest component to the object (specimen) being imaged. Modern objectives, composed of numerous internal glass lens elements, have reached a high state of quality and performance, with the extent of correction for aberrations and flatness of field determining the usefulness and cost of an objective (see Figure 1). Construction techniques and materials used to manufacture objectives have greatly improved over the course of the past 100 years. Today, objectives are designed with the assistance of computer-aided-design systems using advanced rare-element glass formulations of uniform composition and quality having highly specific refractive indices. The enhanced performance that is demonstrated using these advanced techniques has allowed manufacturers to produce objectives that are very low in dispersion and corrected for most of the common optical artifacts such as coma, astigmatism, geometrical distortion, field curvature, and spherical and chromatic aberration (1). Not only are microscope objectives now corrected for more aberrations over wider fields but also image flare has been dramatically reduced with a substantial increase in light transmission, yielding images that are remarkably bright, sharp, and crisp. Three critical design characteristics of the objective set the ultimate resolution limit of the microscope (4). These include the wavelength of light used to illuminate the specimen, the angular aperture of the light cone captured by the objective, and the refractive index in the object space between the objective front lens and the specimen. Resolution for a diffraction-limited optical microscope can be described as the minimum detectable distance between two closely spaced specimen points:

A high precision method for measuring very small capacitance changes

A novel method for measuring very small capacitance changes based on capacitance-to-phase angle conversion is introduced in this article. This new method is the improved or linearized version of the nonlinear capacitance-to-phase angle conversion method. The main features of this scheme are the very good linearity, extremely high stray immunity and a very high resolution. The experimental results of the prototype version of this scheme have also been reported. By using this prototype and a simple capacitive transducer, a minimum detectable distance of about 16 nm can be achieved. This means that a capacitance change of about 0.7 fF (0.7×10−15 F) in a capacitance of 22 pF can be resolved, so the minimum resolvable relative capacitance is about 32 ppm. By the theory it can be seen that the minimum resolvable relative capacitance of 2 ppm could be achieved by this method.