Real-time Distance Research Articles

Comparison of Beijing MST radar and radiosonde horizontal wind measurements

To determine the performance and data accuracy of the 50 MHz Beijing Mesosphere–Stratosphere–Troposphere (MST) radar, comparisons of radar measured horizontal winds in the height range 3–25 km with radiosonde observations were made during 2012. A total of 427 profiles and 15 210 data pairs were compared. There was very good agreement between the two types of measurement. Standard deviations of difference (mean difference) for wind direction, wind speed, zonal wind and meridional wind were 24.86◦ (0.77◦), 3.37 (−0.44), 3.33 (−0.32) and 3.58 (−0.25) m s−1, respectively. The annual standard deviations of differences for wind speed were within 2.5–3 m s−1 at all heights apart from 10–15 km, the area of strong winds, where the values were 3–4 m s−1. The relatively larger differences were mainly due to wind field variations in height regions with larger wind speeds, stronger wind shear and the quasi-zero wind layer. A lower MST radar SNR and a lower percentage of data pairs compared will also result in larger inconsistencies. Importantly, this study found that differences between the MST radar and radiosonde observations did not simply increase when balloon drift resulted in an increase in the real-time distance between the two instruments, but also depended on spatiotemporal structures and their respective positions in the contemporary synoptic systems. In this sense, the MST radar was shown to be a unique observation facility for atmospheric dynamics studies, as well as an operational meteorological observation system with a high temporal and vertical resolution.

Real-Time Non-Intrusive Assessment of Viewing Distance during Computer Use.

To develop and test the sensitivity of an ultrasound-based sensor to assess the viewing distance of visual display terminals operators in real-time conditions. A modified ultrasound sensor was attached to a computer display to assess viewing distance in real time. Sensor functionality was tested on a sample of 20 healthy participants while they conducted four 10-minute randomly presented typical computer tasks (a match-three puzzle game, a video documentary, a task requiring participants to complete a series of sentences, and a predefined internet search). The ultrasound sensor offered good measurement repeatability. Game, text completion, and web search tasks were conducted at shorter viewing distances (54.4 cm [95% CI 51.3-57.5 cm], 54.5 cm [95% CI 51.1-58.0 cm], and 54.5 cm [95% CI 51.4-57.7 cm], respectively) than the video task (62.3 cm [95% CI 58.9-65.7 cm]). Statistically significant differences were found between the video task and the other three tasks (all p < 0.05). Range of viewing distances (from 22 to 27 cm) was similar for all tasks (F = 0.996; p = 0.413). Real-time assessment of the viewing distance of computer users with a non-intrusive ultrasonic device disclosed a task-dependent pattern.

Interference at the Single Photon Level Along Satellite-Ground Channels.

Quantum interference arising from the superposition of states is striking evidence of the validity of quantum mechanics, confirmed in many experiments and also exploited in applications. However, as for any scientific theory, quantum mechanics is valid within the limits in which it has been experimentally verified. In order to extend such limits, it is necessary to observe quantum interference in unexplored conditions such as moving terminals at large distances in space. Here, we experimentally demonstrate single photon interference at a ground station due to the coherent superposition of two temporal modes reflected by a rapidly moving satellite a thousand kilometers away. The relative speed of the satellite induces a varying modulation in the interference pattern. The measurement of the satellite distance in real time by laser ranging allows us to precisely predict the instantaneous value of the interference phase. We then observed the interference patterns with a visibility up to 67% with three different satellites and with a path length up to 5000km. Our results attest to the viability of photon temporal modes for fundamental tests of physics and quantum communication in space.

Passive 350 GHz Video Imaging Systems for Security Applications

Passive submillimeter-wave imaging is a concept that has been in the focus of interest as a promising technology for personal security screening for a number of years. In contradiction to established portal-based millimeter-wave scanning techniques, it allows for scanning people from a distance in real time with high throughput and without a distinct inspection procedure. This opens up new possibilities for scanning, which directly address an urgent security need of modern societies: protecting crowds and critical infrastructure from the growing threat of individual terror attacks. Considering the low radiometric contrast of indoor scenes in the submillimeter range, this objective calls for an extremely high detector sensitivity that can only be achieved using cooled detectors. Our approach to this task is a series of passive standoff video cameras for the 350 GHz band that represent an evolving concept and a continuous development since 2007. Arrays of superconducting transition-edge sensors (TES), operated at temperatures below 1 K, are used as radiation detectors. By this means, background limited performance (BLIP) mode is achieved, providing the maximum possible signal to noise ratio. At video rates, this leads to a temperature resolution well below 1 K. The imaging system is completed by reflector optics based on free-form mirrors. For object distances of 5–25 m, a field of view up to 2 m height and a diffraction-limited spatial resolution in the order of 1–2 cm is provided. Opto-mechanical scanning systems are part of the optical setup and capable of frame rates of up to 25 frames per second.

Construction of indoor floor plan and localization

Indoor positioning and tracking services are garnering more attention. Recently, several state-of-the-art localization techniques have been proposed that use radio maps or the sensors readily available on smartphones. This paper presents a localization system called construction of indoor floor plan and localization (CALL), which is based on a floor plan, access points (APs), and smartphone sensors. The public access points provide a number of reference points that can be used to build the floor plan automatically, and acquire the user initial position. Moreover, The APs are used to calibrate and adjust the user's position, distance, and direction in real time. Smartphone sensors are used to detect the number of steps and the direction. The proposed method is implemented on a smartphone and tested in real indoor environments. Our experiment with CALL demonstrates that using a static floor plan instead of radio map will avoid the costly database updates and searches that are usually required in other approaches due to signal attenuation. It shows that CALL outperforms the existing works in terms of accuracy and effectiveness in indoor localization.

Depth-Vision Coordinated Robust Architecture for Obstacle Detection and Haptic Feedback

The lightweight and low-cost 3-dimensional depth sensors have gained much attention in the computer vision and gaming industry. While its performance has been proven successful in the gaming industry, these sensors have not been utilized successfully for assistive devices. Leveraging on this gap, this paper presents the design, implementation, and evaluation of a depth-vision coordinated robust architecture for obstacle detection and haptic feedback system for the blind. The proposed system scans the scene in front, converts it into depth matrix, processes the information, to identify obstacles including physical objects and humans, and provide relevant haptic feedback for navigation of the blind. Through design and evaluation, the proposed system has shown to successfully identify objects and humans, perform real-time distance measurements, and provide a working solution.

Proximity Sensing Based on a Dynamic Vision Sensor for Mobile Devices

A dynamic vision sensor (DVS) is a sensor that detects temporal contrast of brightness and has the fastest response time compared to conventional frame-based sensors, which detect static brightness per every frame. The fastest response time allows fast motion recognition, which is a very attractive function in the view of consumers. In particular, its low power consumption due to the event-based processing is a key feature for mobile applications. In recent smartphones based on touch screen, a proximity sensor is equipped to prevent malfunction due to undesired contacts with skin while calling. In addition, the main processor stops the operation of the touch screen and turns off the display, when any object is close to the proximity sensor, to achieve minimizing power consumption. Considering the importance of the power consumption and reliable operations, it is certain that proximity sensing is an essential part in a touch-screen-based smartphone. In this paper, a design of proximity sensing utilizing a DVS is proposed. It can estimate the distance from the DVS to an object by analyzing the spatial information of the reflection of an additional light source. It also uses a pattern recognition based on time-domain analysis of the reflection, during turning on of the light source, to avoid wrong proximity detection by noises such as other light sources and motions. The contributions of the proposed design are in three parts. First, it calculates the accurate distance in real time only with spatial information of the reflection. Second, the proposed design can eliminate environmental noises by using pattern matching based on time-domain analysis, whereas conventional optical proximity sensors, which are mainly used in smartphones, are very sensitive to environmental noises because they use the total amount of brightness for certain periods. Third, our design replaces conventional proximity sensors by holding additional benefits that it utilizes the advantages of DVS.

Математическое моделирование соревновательных игр

Concurrent games, in which participants run some distance in real physical time, are investigated. Petri Markov models of paired and multiple competitions are formed. For paired competition formula for density function of time of waiting by winner the moment of completion of distance by loser is obtained. A concept of distributed forfeit, which amount is defined as a share of sum, which the winner gets from the loser in current moment of time is introduced. With use of concepts of distributed forfeit and waiting time the formula for common forfeit, which winner gets from loser, is obtained. The result, received for a paired competition, was spread out onto multiple concurrent games. Evaluation of common wins and loses in multiple concurrent game is presented as a recursive procedure, in which participants complete the distance one after another, and winners, who had finished the distance get forfeits from participants, who still did not finish it. The formula for evaluation of common winning in concurrent game with given composition of participants is obtained. The result is illustrated with numerical example.

Manoeuvres of spacecraft with flexible appendage in obstacle environment

This paper presents a collision avoidance control scheme for position and large angle manoeuvres of spacecraft with flexible appendage in obstacle environment. Firstly, the method of Lagrange equation is used to model the spacecraft with beam-type appendage. Secondly, independent position and attitude controllers are designed by only using the state of spacecraft as feedback information, without any need to measure the elastic deformation of the beam-type appendage. And then, collision avoidance based on real-time distance information is achieved by applying additional artificial repulsive force and torque to the spacecraft. Bounding boxes in the form of superquadric surfaces are exploited to compute the distance between bodies, and the scheme accounts for not only the geometric shape of the obstacle but also that of the spacecraft with flexible appendage. Finally, the effectiveness of proposed control scheme is demonstrated by numerical case studies.

OdoCapsule: next-generation wireless capsule endoscopy with accurate lesion localization and video stabilization capabilities.

In this paper, we propose a platform to achieve accurate localization of small-bowel lesions and endoscopic video stabilization in wireless capsule endoscopy. Current research modules rely on the use of external magnetic fields and triangulation methods to calculate the position vector of the capsule, leading to considerable error margins. Our platform, entitled OdoCapsule (a synthesis of the words Odometer and Capsule), provides real-time distance information from the point of duodenal entry to the point of exit from the small bowel. To achieve this, OdoCapsule is equipped with three miniature legs. Each leg carries a soft rubber wheel, which is made with human-compliant material. These legs are extendable and retractable thanks to a micromotor and three custom-made torsion springs. The wheels are specifically designed to function as microodometers: each rotation they perform is registered. Hence, the covered distance is measured accurately in real time. Furthermore, with its legs fully extended, OdoCapsule can stabilize itself inside the small-bowel lumen thus offering smoother video capture and better image processing. Recent ex vivo testing of this concept, using porcine small bowel and a commercially available (custom-modified) capsule endoscope, has proved its viability.

Measurement of 3D Printed Structure Using a Peak Detection Method in Dispersive Interferometry

We describe an optical three dimensional (3D) measurement method using white-light dispersive interferometry in the range of 5 μm–150 μm. A spectrometer was employed for real-time wavelength scanning and the distance information was obtained using a simple peak detection method in the spectral domain. Fast measurement time enabled us real-time distance measurement of the specimen. The piezoelectric actuator and capacitance distance sensor was employed for nanometer positioning and measuring distance reference value. This technique can be implemented as a distance measurement unit in white-light scanning interferometry by simply attaching a spectrometer to the conventional system. The results showed an accuracy of better than 60 nm for any position within 5 μm–150 μm. The proposed technique can be used as shape-measuring tool for 3D printed products. Measurement results using the proposed method are also presented. These experimental results show that pthe roposed method can be used as a measurement tool for 3D printed products.

Poe in Cyberspace Technology, Magic, and Quack Physics

Poe in Cyberspace Technology, Magic, and Quack Physics

High precision UTDR measurements by sonic velocity compensation with reference transducer.

An ultrasonic sensor design with sonic velocity compensation is developed to improve the accuracy of distance measurement in membrane modules. High accuracy real-time distance measurements are needed in membrane fouling and compaction studies. The benefits of the sonic velocity compensation with a reference transducer are compared to the sonic velocity calculated with the measured temperature and pressure using the model by Belogol'skii, Sekoyan et al. In the experiments the temperature was changed from 25 to 60 °C at pressures of 0.1, 0.3 and 0.5 MPa. The set measurement distance was 17.8 mm. Distance measurements with sonic velocity compensation were over ten times more accurate than the ones calculated based on the model. Using the reference transducer measured sonic velocity, the standard deviations for the distance measurements varied from 0.6 to 2.0 μm, while using the calculated sonic velocity the standard deviations were 21–39 μm. In industrial liquors, not only the temperature and the pressure, which were studied in this paper, but also the properties of the filtered solution, such as solute concentration, density, viscosity, etc., may vary greatly, leading to inaccuracy in the use of the Belogol'skii, Sekoyan et al. model. Therefore, calibration of the sonic velocity with reference transducers is needed for accurate distance measurements.

Network Teaching System

The network education of colleges or universities has become one of the effective complement to traditional education. The Network education can be divided into autonomous distance education and real-time online distance education which could be applied in different conditions. The Network education has fundamentally changed the teaching method of traditional educations. It may even change the whole ideas on education. It could break out the limit of time and distance. Students will have more flexibility when they begin to study. This article investigates domestic colleges and universities technology ability and the infrastructure, analyzes the cost of software and hardware resources for network education recently, and plans three feasible network teaching system.

Research on Real-Time Optimal Path Algorithm of Urban Transport

Based on the ant colony algorithm, urban real-time traffic optimal path algorithm was designed through restricting search area and search direction of ant colony system, making the real-time traffic and distance as the optimal path weights and regarding intersection turning as the impact of weight value combined with Chinese situation. The algorithm could calculate the optimal path through algorithm complexity test. We obtained a traffic optimal path with timeliness and practical value combined with ant colony algorithm considering multiple parameters.The obtained path enabled user to reach destination within a short time and with the least fuel through actual traffic test. It was regarded as the optimal path. DOI : http://dx.doi.org/10.11591/telkomnika.v12i5.3535 Full Text: PDF

Augmented Reality for Improving Catheterization in Magnetic Resonance Imaging-Guided Cardiac Electrophysiology Therapy1

Augmented Reality for Improving Catheterization in Magnetic Resonance Imaging-Guided Cardiac Electrophysiology Therapy1

Low-Latency Distance Protective Relay on FPGA

The need for high-speed multi-function protective relays in both traditional transmission systems and the new emerging paradigm of the smart grid is growing. As a widely used protective scheme for transmission lines, a distance relay's high speed and reliable operation to clear faults is essential. This paper proposes a real-time low-latency hardware digital distance protective relay on the field programmable gate array (FPGA). Taking advantage of inherent hard-wired architecture of the FPGA, the proposed hardware distance relay design is paralleled and fully pipelined to achieve low latencies in various relay modules which are developed in textual VHDL language. This low-latency feature allows fast operating and data throughput so that the relay can handle high-frequency sampled data and reach higher computational efficiency. In addition, the parallelism and hardwired architecture of the FPGA makes the design more reliable in computation than the sequential software-based numeric relay. The FPGA-based distance relay can operate on both phasor-based signals and instantaneous signals with 2.09 μs and 0.35 μs latency respectively based on the clock frequency of 100 MHz. The hardware relay is tested in real-time by feeding it with generated faulted current and voltage data for typical faults and the relay response recorded. The results demonstrate the speed and effectiveness of the hardware distance relay.

Design and Implement of the Car Reversing Automatic Anti-Collision Control System

There are considerable difference between the actual distance and that measured by infrared or ultrasonic ranging. The car reversing isnt intelligent enough. In order to solve the issues, this paper design an automatic car reversing auxiliary systems based on monocular sight. The system hardware mainly consists of image collection module, embedded micro-controller, and electronic braking module. On the basis of the distance measurement algorithm based on monocular sight, the real-time distance to the front vehicle can be measured and can be auxiliary controlled via the data exchange among vehicle electrical control units. The vehicle dynamic driving experiment verifies the high reliability of the vehicle automatic reversing auxiliary system based on monocular sight. The distance measurement errors are less than 2% when the distance to the front barriers is in the range of 20m~70m. The system can satisfy the real-time requirements for the vehicle intelligent auxiliary braking.

基于FPGA的汽车单目测距系统设计

In order to avoid rear-end collision,an embedded car ranging system based on the field-programmable gate array(FPGA)is presented and its applied algorithms such as image acquisition,image processing,monocular distance measurement based on small hole imaging and etc are investigated. The hardware platform for the design is Terasic DE2FPGA development board.The system uses a single camera to measure the distance in real time between two cars.It acquires the CVBS(Composite Video Broadcast Signal)video stream from PAL camera.The system detects the range by image graying,filtering,detecting edge,dilation,erosion,locating license plate,computing the size and liquid crystal display.The whole system uses Verilog hardware description language to realize image acquisition and display,all kinds of image processing algorithm,license plate location and distance measurement algorithm.The image processing speed reaches 25frame/s which greatly improves the real-time performance of the system.Experimental results indicate that the maximum distance error is only 2.57%.The system can be used for the auxiliary driving to prevent the collision or intelligent robot vision.

Improved Urban Transport Optimal Path Based on Ant Colony Algorithm

Based on ant colony algorithm, urban real-time traffic optimal path algorithm was designed through restricting search area and direction, making real-time distance as optimal path weights and regarding turning as the impact of weight value in Chinese traffic. The algorithm could calculate the optimal path through algorithm complexity test. The obtained path enabled user to reach destination within a short time and with the least fuel through actual traffic test. It is regarded as the optimal path.