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The principle and performance of Synthetic Impulse and Antenna Radar(SIAR) are analyzed with the concept of 3D matched filtering. The discussion here is concentrated on the characteristics of SIAR in the case of three dimensions....
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The principle and performance of Synthetic Impulse and Antenna Radar(SIAR) are analyzed with the concept of 3D matched filtering. The discussion here is concentrated on the characteristics of SIAR in the case of three dimensions. The results obtained are helpful for designing this new style radar.
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Synthetic cathinones, such as 3,4-methylenedioxypyrovalerone (MDPV), are recreational drugs of abuse often identified in 'bath salts' preparations. Humans report compulsive patterns of bath salts use, and previous work suggests th...
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Synthetic cathinones, such as 3,4-methylenedioxypyrovalerone (MDPV), are recreational drugs of abuse often identified in 'bath salts' preparations. Humans report compulsive patterns of bath salts use, and previous work suggests that a subset of rats develop unusually high levels of MDPV self-administration. This study aims to test the hypothesis that high levels of impulsivity (e.g., inability to withhold responding for a sucrose reward) will predispose rats to high levels of MDPV self-administration relative to rats with lower levels of impulsivity. The 1-choice serial reaction time task (1-CSRTT) was used to assess impulsivity (i.e., premature responding) in 10 female and 10 male Sprague Dawley rats. Rats were then allowed to self-administer 0.032 mg/kg/inf MDPV or 0.32 mg/kg/inf cocaine, after which full dose-response curves for MDPV (0.001-0.1 mg/kg/inf) or cocaine (0.01-1 mg/kg/inf) were generated under a FR5 schedule of reinforcement. After a history of self-administering MDPV or cocaine, impulsivity was reassessed under the 1-CSRTT, prior to evaluating the acute effects of MDPV (0.032-0.32 mg/kg) or cocaine (0.1-1 mg/kg) on impulsivity. Level of impulsivity was not correlated with subsequent levels of either MDPV or cocaine self-administration, and level of drug self-administration was also not correlated with subsequent levels of impulsivity, although acute administration of MDPV and cocaine did increase premature responding. In failing to find direct relationships between either impulsivity and subsequent drug-taking behaviour, or drug-taking behaviour and subsequent assessments of impulsivity, these findings highlight the complexity inherent in the associations between impulsive behaviour and drug-taking behaviour in both animal models and humans.
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Ultrasonic technology can be used to monitor the crystallization of fats and determine solid fat content (SFC) online. Ultrasonic waves are attenuated as crystals form and grow, and this attenuation occurs first at higher frequenc...
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Ultrasonic technology can be used to monitor the crystallization of fats and determine solid fat content (SFC) online. Ultrasonic waves are attenuated as crystals form and grow, and this attenuation occurs first at higher frequencies. The attenuation of the ultrasonic signal does not depend on the induction times of crystallization of the systems, or on their thermal behavior; but it does depend on SFC and on microstructure, particularly on the crystal size. At low SFC values (≈5%), bigger crystals generate more attenuation. At intermediate SFC values (≈10%), crystal size does not affect signal attenuation and SFC is the key factor responsible for signal attenuation. At high SFC values (up to 20%), crystal size again seems to be the factor that controls attenuation.
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Timed arrays are the time-domain counterpart of phased arrays, where each array element is excited by wideband instead of narrowband signals. By referring to idealized, but meaningful canonical configurations, the array parameters...
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Timed arrays are the time-domain counterpart of phased arrays, where each array element is excited by wideband instead of narrowband signals. By referring to idealized, but meaningful canonical configurations, the array parameters in the transmit and receive mode are defined in a simple way, by following a purely time-domain intuitive analysis. Obtained results extend steady-state concepts of beamwidth, directivity, gain, effective receiving area, Fresnel and Fraunhofer regions to the case of transient excitation. Application is made to both real and synthetic arrays. The final main conclusion is that the role of the carrier wavelength associated with narrowband excitation is taken by the spatial width of the (carrierless) pulse. This result appears to be rather robust, because it turns out to be independent from the different norms used in the definition of the antenna parameters: it sheds light on the physics of the transient radiation and may be very useful for initiating a more technical analysis of the array performance.
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Sparse-array Synthetic Impulse and Aperture Radar(SIAR) can isotropically radiate by employing multiple frequencies (synthetic pulse) and multiple antennas(synthetic antenna). According to Ambiguity Function(AF), its range resolut...
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Sparse-array Synthetic Impulse and Aperture Radar(SIAR) can isotropically radiate by employing multiple frequencies (synthetic pulse) and multiple antennas(synthetic antenna). According to Ambiguity Function(AF), its range resolution depends only on bandwidth of trans- Mitted signals, however, the distance grating lobes emerge when increasing the time-bandwidth Product of transmitted signals. The performance of pulse compression is analyzed with the Transmitted signals modulated by phase-coded sequences. It is seen that greater ratio of pulse Compression and suppression of range sidelobe in SIAR can be obtained be obtained, and its effective range And range resolution is increased as well.
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Interests on ester liquids as replacement of mineral oil in large power transformers are growing in recent years. This paper presents experimental studies on streamer and breakdown in synthetic and natural esters. Lightning impuls...
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Interests on ester liquids as replacement of mineral oil in large power transformers are growing in recent years. This paper presents experimental studies on streamer and breakdown in synthetic and natural esters. Lightning impulse voltage was chosen when considering the practicality of standard tests of transformer industry. First, streamer length, velocity, shape and mode were analyzed based on optical images obtained by a multi-channel ultra high speed camera. Under the same voltage level, streamer in both natural and synthetic esters propagates faster and further, with more branches, than in mineral oil. Breakdown tests at various gaps from 15 mm to 100 mm were conducted, and it was found that fast streamer led breakdown becomes statistically dominant in a large gap under lightning impulse and ester liquids have lower breakdown voltage than mineral oil due to their low tolerance to fast streamer. Therefore a relationship between the results under lightning impulse and previously published results under step voltage was built up and an empirical formula was obtained to predict the breakdown voltage of esters at very large gaps.
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A method for the specification of weighting functions for a spaceborne/airborne interferometric synthetic aperture radar (SAR) sensor for Earth observation and environment monitoring is introduced. This method is based on designin...
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A method for the specification of weighting functions for a spaceborne/airborne interferometric synthetic aperture radar (SAR) sensor for Earth observation and environment monitoring is introduced. This method is based on designing an optimum mismatched filter which minimizes the total power in sidelobes located out of a specified range region around the peak value point of the system point-target response, i.e. impulse response function under the constraint imposed on the peak value. It is shown that this method allows achieving appreciable improvement in accuracy performance without degradation in the range resolution.
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Composite materials based on synthetic leathers from Polyvinyl Chloride and Polyurethane with knitted fabric support are increasingly used in many sectors of industry. Two synthetic leathers have been analysed both through experim...
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Composite materials based on synthetic leathers from Polyvinyl Chloride and Polyurethane with knitted fabric support are increasingly used in many sectors of industry. Two synthetic leathers have been analysed both through experimental and analytical methods in order to evaluate their elastic properties. The analytical evaluation of material elasticity was conducted based on a micromechanical approach, taking into account the Krenchel's coefficient for Polyester fibre orientation and based on the analytical models of Leaf and Glaskin and Chamis. Experimental data was gathered using microscopic analysis and the mechanical impulse excitation test method. Results showed a good correlation with that from the experimental study. Thus, it was confirmed that the Leaf and Glaskin model and the Chamis model have a good accuracy in prediction of fibres orientation and respectively elastic properties of synthetic leather based on plain jersey.
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This paper describes experimental studies on streamer propagation in synthetic ester and mineral oil under lightning impulse voltage. These studies are concentrated around the small electrode gaps (15 and 20 mm) of the point-plane...
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This paper describes experimental studies on streamer propagation in synthetic ester and mineral oil under lightning impulse voltage. These studies are concentrated around the small electrode gaps (15 and 20 mm) of the point-plane electrode arrangement. The spatial shapes of the developing streamers, oscillograms of light emitted and propagation velocities were analyzed and compared. Two streamer propagation modes were observed during the studies performed. Slow 2nd mode streamers developed below the so-called acceleration voltage while fast 3rd mode streamers developed at acceleration voltage and above. Independently of the liquid used the registered streamers shapes corresponding to a given voltage polarity were identical. Concerning the light oscillograms, higher frequencies of light pulses were observed in the case of synthetic ester. A significant difference between both the considered liquids was however noticed in the threshold value of the testing voltage at which the 3rd mode streamers appeared. Fast positive streamers started to develop in synthetic ester at lower testing voltage (of about 26 kV for 20 mm gap and 20 kV for 15 mm gap) than in the case of mineral oil. For negative polarity of lightning impulse, within the applied testing voltages, 3rd mode streamers were observed only in synthetic ester. For both electrode gaps acceleration voltage for negative polarity was 2.2 of estimated inception voltage. This allowed forming the conclusion that synthetic esters have a lower ability of preventing the development of fast and energetic streamers, even at small (15 and 20 mm) electrode gaps.
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Through-the-wall imaging (TWI) is an emerging area of research and development which is very much useful in urban warfare situations. Ultra-wide band range radar is the best suitable for this application where this range of signal...
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Through-the-wall imaging (TWI) is an emerging area of research and development which is very much useful in urban warfare situations. Ultra-wide band range radar is the best suitable for this application where this range of signals has the capability of penetrating through the materials but still can provide better resolution. The incorporation of signal processing techniques on the raw data will give better representation of the scanned scene. The paper uses impulse radar for TWI, and back projection algorithm is used to retrieve the B-scan signal. A constant gain of factor 100 is used to increase the echo strength. Singular value decomposition is used to reduce the clutter from the B-scan signal and the peak signal to noise ratio is observed to be -3.79 dB.
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