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This paper presents a technical vision system designed to resolve multiple tasks which are fundamental for autonomous navigation. These tasks include detecting the presence of a significant obstacle for a mobile robot, locate its ...
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This paper presents a technical vision system designed to resolve multiple tasks which are fundamental for autonomous navigation. These tasks include detecting the presence of a significant obstacle for a mobile robot, locate its position in the mobile robot's field of view and create a digital map of the obstacle's visible surface with metrological accuracy. This technical vision system has been introduced and explained in other publications; therefore this paper focuses mostly on signal conditioning, processing and resolution increase for mobile robot navigation.
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In some areas of the North Sea there are irregular highamplitude events that some call "gull-wing" reflections because of their characteristic appearance on seismic sections. The Oseberg area, the site of a recently acquired ocean...
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In some areas of the North Sea there are irregular highamplitude events that some call "gull-wing" reflections because of their characteristic appearance on seismic sections. The Oseberg area, the site of a recently acquired ocean-bottom cable (OBC) 3D survey, is severely affected by these anomalies, which are scattered over the area at a depth of about 1.5 km. Some gull-wing anomalies have been drilled and are seen in log data to have a thickness of up to about 50 m and a P-velocity of around 5500 m/s. The high velocity of these irregular features causes significant distortion in depth imaging of Oseberg seismic data, causing both vertical and lateral displacement of deeper events. Different approaches were explored to resolve the high-velocity anomalies during depth imaging of the OBC 3D data. One method that has proven successful is to use results of prestack AVO inversion to insert anomalies in the velocity model. Another method is high-resolution common-image-point (CIP) tomography using offset-vector-tile (OVT) input, which is also able to resolve a smooth representation of the gull-wing anomalies. Both of these methods reduce the distortion caused by the gull-wing anomalies and give improved depth-imaged results.
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Super High Resolution Powder Diffractometer SuperHRPD [1] at J-PARC have suffered damage by the Great East Japan Earthquake on 11 March 2011. After temporarily restoration work, the general user program has been started since Apri...
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Super High Resolution Powder Diffractometer SuperHRPD [1] at J-PARC have suffered damage by the Great East Japan Earthquake on 11 March 2011. After temporarily restoration work, the general user program has been started since April 2012. Full-fledged restoration of the temporarily restored devices is being carried out in 2013. The absorber materials for two disk choppers were replaced to ~(10)B_4C which improved quality of incident spectrum. The new detector system of 8 mm diameter position sensitive detectors was developed, and the test experiments showed excellent results.
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A new signal prediction algorithm based on Prony model applied on folding and interpolating (F&I) ADC is presented. The signal prediction algorithm employs Prony model to build the autoregressive moving average process (ARMA) which can achieve accuracy power spectrum estimation. This ADC system can support multi-mode multi-band signals converting aimed for software defined radio. By canceling the predicted part, this proposed system increases the input dynamic range of ADC and improves its resolution from 10bits to 14bits under 250MS/s sampling rate....
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A new signal prediction algorithm based on Prony model applied on folding and interpolating (F&I) ADC is presented. The signal prediction algorithm employs Prony model to build the autoregressive moving average process (ARMA) which can achieve accuracy power spectrum estimation. This ADC system can support multi-mode multi-band signals converting aimed for software defined radio. By canceling the predicted part, this proposed system increases the input dynamic range of ADC and improves its resolution from 10bits to 14bits under 250MS/s sampling rate.
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High resolution terahertz (THz) spectroscopy is available for sensitive gas detection and also useful for vibrational mode analysis of organic molecules. We developed a widely frequency tunable (0.1–7.5 THz), monochromatic cohere...
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High resolution terahertz (THz) spectroscopy is available for sensitive gas detection and also useful for vibrational mode analysis of organic molecules. We developed a widely frequency tunable (0.1–7.5 THz), monochromatic coherent THz-wave Signal Generator on the basis of difference frequency generation (DFG) in a GaP crystal via excitation of phonon-polariton mode under small-angle non-collinear phase matching condition. The pump beams for DFG were supplied from semiconductor lasers as seed beams after amplification by fiber amplifiers. Then we applied it as a light source for a high resolution and high accuracy THz spectrometer. Combining with a superconducting Transition Edge Sensor (TES) bolometer cooled by a pulse tube refrigerator, a non-stop spectrometer system was realized. The system had advantages of high stability, small size, easy operation and maintenance free in the lifetime of the pump lasers. As frequency resolution and accuracy were limited by those of pump laser beams, we have newly developed a frequency control system for two beams at the same time. Frequency resolution of 8 MHz constant in whole the frequency tunable range and absolute accuracy of better than 3 MHz were evaluated by the measurements of water vapor absorptions in vacuum.
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Terahertz superconducting detector has high sensitivity but it's difficult to achieve high-efficiency for large-scale observation with a single detector. To fully improve efficiency and resolution, a high sensitivity terahertz ima...
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Terahertz superconducting detector has high sensitivity but it's difficult to achieve high-efficiency for large-scale observation with a single detector. To fully improve efficiency and resolution, a high sensitivity terahertz imaging system designed using compressive sensing (CS) principles was proposed in this paper, which uses a single superconducting detector replacing complex and high-cost array detector. With a random selection from linear encoded masks, the proposed imaging system acquired enough incoherent measurements using a 0.85THz superconducting detector. A regularized ?_1-norm reconstruction method was employed to reconstruct the imaged scene with fewer measurements compared to the size of the image. Experimental results demonstrated that the proposed imaging system could achieve the improvement of imaging efficiency and resolution.
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We propose a Terahertz tomography system using self-heterodyne detection with phase noise compensation. The phase noise compensation actively reduces phase noise from laser sources and offers improved resolution and reproducibilit...
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We propose a Terahertz tomography system using self-heterodyne detection with phase noise compensation. The phase noise compensation actively reduces phase noise from laser sources and offers improved resolution and reproducibility of the tomography system.
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Generation of femtosecond electron bunches has been investigated for a light source based on electron bunches and improvement of time resolution in time-resolved measurements. In this study, temporal electric fields from electron ...
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Generation of femtosecond electron bunches has been investigated for a light source based on electron bunches and improvement of time resolution in time-resolved measurements. In this study, temporal electric fields from electron bunches using a photoconductive antenna (PCA) with radial microstructures were measured. Radially polarized terahertz (THz) pulses from femtosecond electron bunches were generated by coherent transition radiation (CTR). Electric-field-induced current from the PCA depending on THz electric field was measured.
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The resolving power of any digital measuring system is the main limiting factor influencing its final accuracy. Introducing noise to the system can improve the accuracy by changing the level of quantization; however, this may not ...
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The resolving power of any digital measuring system is the main limiting factor influencing its final accuracy. Introducing noise to the system can improve the accuracy by changing the level of quantization; however, this may not be easy to employ in practice. For a digital weighing scale the method may be implemented by repeating measurement and addition of a random known weight to the object being weighed every time the weight is measured. The method may be called Multi-Measurement of a single quantity Using Noise (MMUN). The theory of the method has already been proved. The current papers employ the method for a particular application in which the area of an object is being measured by a vision system experimentally. The results of experimental measurements show improvement of the accuracy beyond the resolution of the measuring device.
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The high-frequency (HF) oceanographic radar system located at the coast is well-known as a tool for synoptic on-line mapping. Recently oceanographic radar systems have been officially recognized by the International Telecommunicat...
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The high-frequency (HF) oceanographic radar system located at the coast is well-known as a tool for synoptic on-line mapping. Recently oceanographic radar systems have been officially recognized by the International Telecommunication Union (ITU) to have their own frequency bands. However, the assigned spectral bandwidth for radar signals is quite narrow. It leads to loosing the required range resolution. To avoid this disadvantage new high-resolution processing techniques can be applied. The signal processing sequence is considered in order to improve target range resolution by simple software modification. A test example of high-resolution technique for range processing is shown using measured signals of oceanographic HF frequency modulated continuous wave (FMCW) radar.
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