摘要 :
Vehicle speeds are often measured by intelligent transportation systems (ITSs) by utilizing sensors or software solutions. Our previous work proposed the Lin–Chang–Huangfu (LCH) scheme to compute the cell residence times by the ...
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Vehicle speeds are often measured by intelligent transportation systems (ITSs) by utilizing sensors or software solutions. Our previous work proposed the Lin–Chang–Huangfu (LCH) scheme to compute the cell residence times by the standard counter values in mobile telecommunications switches. In this paper, we use mathematical and statistical developments to investigate the accuracy of the LCH scheme by deriving the bias of the cell residence times computed in this scheme. Then, we extend the LCH scheme with some filtering and compensation techniques for vehicle speed estimation and validate our approach with vehicle detector (VD) measurements at National Highway 3, Longtan Township, Taoyuan County, Taiwan. Our study indicates that the LCH scheme is an effective approach to vehicle speed estimation.
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A novel soft strain sensor capable of withstanding strains of up to 100% is described. The sensor is made of a hyperelastic silicone elastomer that contains embedded microchannels filled with conductive liquids. This is an effort ...
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A novel soft strain sensor capable of withstanding strains of up to 100% is described. The sensor is made of a hyperelastic silicone elastomer that contains embedded microchannels filled with conductive liquids. This is an effort of improving the previously reported soft sensors that uses a single liquid conductor. The proposed sensor employs a hybrid approach involving two liquid conductors: an ionic solution and an eutectic gallium-indium alloy. This hybrid method reduces the sensitivity to noise that may be caused by variations in electrical resistance of the wire interface and undesired stress applied to signal routing areas. The bridge between these two liquids is made conductive by doping the elastomer locally with nickel nanoparticles. The design, fabrication, and characterization of the sensor are presented.
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The wavelength-selective infrared absorptance of a single-layered aluminum subwavelength structure (SWS) is optimized using a hybrid numerical scheme comprising the rigorous coupled-wave analysis method and a genetic algorithm. Th...
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The wavelength-selective infrared absorptance of a single-layered aluminum subwavelength structure (SWS) is optimized using a hybrid numerical scheme comprising the rigorous coupled-wave analysis method and a genetic algorithm. The results show that the optimized SWS yields a strong absorptance peak (0.99) and a full-width-at-half-maximum (FWHM) of 1.42 $mu{rm m}$. In addition, it is shown that the absorptance spectrum of the SWS is insensitive to the angle of incidence of the incoming light and the grating period, but shifts toward a longer (shorter) wavelength as the grating thickness or grating ridge width is increased (decreased). The enhanced absorptance is examined by computing the governing equations of the excitations of Rayleigh-Wood anomaly, surface plasmon polaritons, cavity resonance, and magnetic polaritons. The magnetic field patterns and Poynting vector distribution within the grating structure are also analyzed to support the physical mechanism using the finite-difference time-domain (FDTD) method. The results indicate that the absorptance peak of the SWS is the result of cavity resonance. Also, for a double-layered SWS comprising an aluminum grating and a dielectric layer, a widening of the absorptance spectrum occurs. Overall, the results presented in this study show that SWS gratings which can be easily manufactured using microfabrication technology provide a simple and versatile solution for such applications in tailoring the spectral absorptance used for infrared detection, energy harvesting, and so on.
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Illegal use of electric energy is a widespread practice in many parts of the world. Smart metering enables the improvement of customer load model, theft and stressed asset detections. In this paper, a state estimation based approa...
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Illegal use of electric energy is a widespread practice in many parts of the world. Smart metering enables the improvement of customer load model, theft and stressed asset detections. In this paper, a state estimation based approach for distribution transformer load estimation is exploited to detect meter malfunction/tampering and provide quantitative evidences of non-technical loss (NTL). A measure of overall fit of the estimated values to the pseudo feeder bus injection measurements based on customer metering data aggregated at the distribution transformers is used to localize the electricity usage irregularity. Following the state estimation results, an analysis of variance (ANOVA) is used to create a suspect list of customers with metering problems and estimate the actual usage. Typical Taiwan Power Company (TPC) distribution feeder data are used in the tests. Results of NTL detection under meter defect and energy theft scenarios are presented. Experiences indicate that the proposed scheme can give a good trace of the actual usage at feeder buses and supplement the current meter data validation estimation and editing (VEE) process to improve meter data quality.
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This paper shows that, by simply adding a triangle aperture (TA) in front of a camera lens, iris autofocus can be easily achieved. Through the TA, the corneal reflection of a light source forms a triangle glint on the image plane....
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This paper shows that, by simply adding a triangle aperture (TA) in front of a camera lens, iris autofocus can be easily achieved. Through the TA, the corneal reflection of a light source forms a triangle glint on the image plane. The size and orientation of the glint can be used to infer the amount and the direction of the focus adjustment. A gradient-descent autofocus control law is proposed for uncalibrated lenses. Results from theoretical analysis and real experiments show that the proposed method is more efficient and accurate than the conventional circular aperture approach.
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A simple low-profile antenna for octa-band LTE/WWAN operation in the internal mobile phone application is proposed and studied in this article. Consisting of a feeding strip and a coupling strip mainly, the presented antenna can b...
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A simple low-profile antenna for octa-band LTE/WWAN operation in the internal mobile phone application is proposed and studied in this article. Consisting of a feeding strip and a coupling strip mainly, the presented antenna can be easily printed on the no-ground area of the top of a FR4 substrate, yet it occupies only a size of $15times 40 {rm mm}^{2}$ and has a height of 3.5 mm. In this scheme, a chip inductor $(L_{1}=20 {rm nH})$ is loaded in the long inductive strip, which can form a parallel resonant structure together with the coupling strip section close to the feeding strip. With these presences, a double-resonance mode ($lambda/4$ resonant mode) is successfully generated at about 720 and 900 MHz to cover the lower band of LTE700/GSM850/900 (704–960 MHz). While the desired upper band of DCS1800/PCS1900/UMTS2100/LTE2300/2500 (1710–2690 MHz) can be obtained with the help of second two resonant modes, including a high-order $lambda/2$ resonant mode at 1800 MHz and a $lambda/4$ resonant mode at 2550 MHz. That is to say that those two wide operating bandwidths are achieved to cover all the octa-band LTE/WWAN operation. Good radiation efficiency and antenna gain for frequencies over the desired operating bands is obtained. Detailed design considerations of the proposed antenna are described, and both experimental and simulation results are also presented and discussed.
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The analytical expressions of the external and internal electric fields for an anisotropic particle in electromagnetic (EM) beams are presented by transforming anisotropic dielectric particle into the isotropic one based on the sc...
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The analytical expressions of the external and internal electric fields for an anisotropic particle in electromagnetic (EM) beams are presented by transforming anisotropic dielectric particle into the isotropic one based on the scales transformation of EM theory. The theoretical expressions are in good agreement with that in literatures. Taking the case of elliptical Gaussian beam, simulations of influence induced by dielectric tensor and the waists, etc., on the fields are demonstrated. The numerical simulations show that the electric field increases with the augment of beam and the higher order electric field is much smaller than the lower field.
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The electronic package with lead-free welding processes must be performed at higher temperature whereas the heat induces to mechanical stress. In this letter, we fabricate a low-$k$ SiOC dielectric comb capacitor with dual damasce...
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The electronic package with lead-free welding processes must be performed at higher temperature whereas the heat induces to mechanical stress. In this letter, we fabricate a low-$k$ SiOC dielectric comb capacitor with dual damascene (DD) structures to study the mechanical stress influence on leakage current $I_{rm leak}$ in DD by bending samples. Tensile stress causes increase of the $I_{rm leak}$ because of the decrease of energy band barrier $Phi$ of SiOC dielectric. In contrast, compress stress increases $Phi$ of SiOC and decreases its $I_{rm leak}$. Finally, we conclude that the electron transport in DD is dominated by Schottky emission. We found that the variation of $I_{rm leak}$ is attributed by the change of energy band barrier under mechanical stress.
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