KEYWORDS: Solar cells, Optical spheres, Solar energy, Reconnaissance, Signal detection, Target detection, Absorption, Signal processing, Power supplies
Under the requirements of flexible, stealthy and miniaturize, the energy system has become the most critical factor that constraint the performance of smart unmanned equipment. Due to its advantages of convenient movement and strong environmental adaptability, the sphere platform shows broad prospects in military and civilian application. This paper designed an energy self-sufficient sphere platform equipped with intelligence reconnaissance device. The energy module of the device consists of an inscribed polyhedron solar cell array. The high power density energy storage component inside the sphere realizes energy storage and power supply for the signal transmission module. The sphere is equipped with an autonomous mobile unit and a detection unit, activated by outside trigger signal, and can be used in close reconnaissance, short-range detection and strategic destruction. The output power of the prototype machine produced by 3D printing is close to the theoretical result, and it maintained in high value during device rotation, laying the technical foundation for the practical application of this spherical platform.
High-quality InAs1-xSbx films with x=0.06 have been successfully grown on InAs (100) substrates by liquid phase epitaxy. Two methods are used to characterize the electrical properties of InAsSb film. One is to grow InAsSb epilayer on p-type InAs substrate, which, in combination with the n-type epilayer, forms a p-n junction to prevent the parallel conduction from the substrate. The other is that both the conductive InAs substrate and the dislocation layer between InAs and InAsSb are removed completely by chemical mechanical polishing method to get InAsSb film glued onto insulating sapphire substrate. The influence of conductive InAs substrate on the electrical properties of InAsSb film is eliminated effectively.
Magnetic metallic multilayers separated by nonmagnetic metal films are of great importance in magnetoelectronics and spintronics, due to their capacity of giving rise to giant magneto-resistance as well as the electric field control of ferromagnetism. Co/Pt multilayers are one of the typical platforms that own perpendicular magnetic anisotropy which can be tuned in various ways. Since previous investigations focus on the anomalous Hall(transverse) resistivity which characterizes the magnetization of the multilayers, much less attention has been paid to the longitudinal resistivity. In this work, we find that the longitudinal resistivity also gives rich phenomena that need further theoretical treatment. We have grown two Co/Pt multilayer structures that have different spacings between neighboring ferromagnetic layers. The one with smaller spacing shows a superparamagnetic behavior in its Hall resistivity even at a temperature as low as 1.5 K, but the longitudinal resistivity shows a well established hysteresis. The other sample shows square hysteresis in the Hall resistivity at all available temperatures up to 300 K, while the longitudinal resistivity gives no significant signals because they are mostly engulfed in the noises. The corresponding temperature dependence of the coercive field are also different. While the former gives an approximately exponential function of the temperature T, the latter can be divided to two zones, each of which can be characterized by a lnTs dependence, where s is not necessarily an integer. Such distinct features may be deeply related to the microstructures as well as the magnon scattering, which require further investigations.
The self-assembled type-II GaSb quantum dots (QDs) were successfully grown on semi-insulting GaAs (100) substrate by the liquid phase epitaxy (LPE) technique with growth temperature ranging from 520 to 580 oC. The morphology of GaSb QDs including size, shape and density was investigated by atomic force microscopy measurement and scanning electron microscope measurement, respectively. The cap layer with scores of nanometers, which is characterized by Profile-system, is obtained for the photoluminescence measurement and device fabrication.
Laser has been widely used in spectroscopic and metrological measurement. High-precision laser metrology is affected by the refractive index of air. In order to apply the algorithm for the refractive index of air in some situation where low calculation complexity and high-precision are needed, the algorithm of the refractive index of Rueger is updated. As the errors of Rueger’s algorithm are mainly affected by temperature, humidity, and the concentration of carbon dioxide in the atmosphere as well as laser wavelength, we do some revisions about these effects of the factors of atmosphere in Rueger’s algorithm. The conditions of standard air is redefined in this paper because of the average concentration of carbon dioxide in the atmosphere has been changed in the past few decades. As the concentration of carbon dioxide in the air is not constant, the effect of carbon dioxide on the refractive index of air is taken into consideration in the updated algorithm. The updated algorithm adapts to the real atmosphere well. The effects of dry air and humid air on the algorithm are also corrected, and the refractive index of air calculated by the updated algorithm is much closer to that of Philip E.Ciddor’s algorithm defined as reference algorithm in the paper because of its high-precision. The performance of the updated algorithm is also analyzed in this paper. It is compared to that of the reference algorithm and the real measured data. Comparing results show that the performance of the algorithm has been improved after the correction. Comparing to the reference algorithm, the performance of the updated algorithm is a little bit lower, but the updated algorithm is much simpler and easier to be applied. Comparing to Rueger’s algorithm, the performance of the updated algorithm is much higher and the complexity of the updated algorithm increases very small. The updated algorithm meets low calculation complexity and high-precision requirements.
In this paper, we propose a Driver’s Awareness Catching System to sense the driver’s awareness. The system consists of a fisheye camera and a Kinect. The Kinect mounted inside vehicle is used to recognize and locate the 3D face of the driver. The fisheye camera mounted outside vehicle is used to monitor the road. The relative pose between two cameras is calibrated via a state-of-the-art method for calibrating cameras with non-overlapping field of view. The camera system works in this way: First, the SDK of Kinect released by Microsoft is used to tracking driver’s face and capture eye’s location together with sight direction. Secondly, the eye’s location and the sight direction are transformed to the coordinate system of fisheye camera. Thirdly, corresponding view field is extracted from fisheye image. As there is a small displacement between driver’s eyes and the optical center of fisheye camera, it will lead to a view angle deviation. Finally, we did a systematic analysis of the error distribution by numerical simulation and proved the feasibility of our camera system. On the other hand, we realized this camera system and achieved desired effect in realworld experiment.
The influence of growth conditions on the microstructures of Bi2Te3 films grown on (111) and (100)-oriented GaAs substrates by hot wall epitaxy is investigated using X-ray diffraction, scan electron microscopy, energy dispersive spectrum, high resolution transmission electron microscopy and micro-Raman spectroscopy. It is found that high quality Bi2Te3 thin films with c-axis oriented are prepared when the temperatures of the Bi2Te3 source and (111) GaAs substrate are 505°C and 375°C respectively. The low substrate temperature and the crystal symmetry mismatch between the (100) GaAs substrate and Bi2Te3 epitaxial film make the crystalline grains mis-oriented, which are responsible for the degradation of the crystal quality of Bi2Te3 films. In addition, the low substrate temperature could lead to the non-stoichiometry.
Single crystalline InAs0.016Sb0.984 film has been successfully grown on (100) InSb substrate by LPE method. A large supercooling (ΔT = 15 °C) had been used to prevent substrate from dissolving into the epilayer. High resolution X-ray diffraction (HRXRD) measurement was used to characterize the crystal quality of the film. Only (200) and (400) peaks were observed from the XRD spectrum, indicating that the film was single crystalline with (100) orientation. The Fourier transform infrared (FTIR) transmission spectrum of the film at room temperature revealed 7.77 μm cut-off wavelength of the film. The lattice dynamics of the epilayer was studied by Raman scattering, suggests two-mode behavior of the optical phonons.
Cd1-xZnxTe single crystals were grown by Vertical Bridgman method. The optic and dielectric properties of Cd1-xZnxTe (× = 0.04) single crystals in 0.2−2.5 THz frequency range have been investigated by using transmission-type THz timedomain spectroscopy. Two absorption modes at 1.6 THz and at 2.1 THz were observed, which were attributed to the quasi-local mode of ZnTe in CdTe and to the CdTe 2TA phonon process, respectively. The complex refractive index and dielectric function were extracted from the measured transmittance and phase shift in 0.2−2.5 THz range
We have studied the annealing effects on InAsSb thick films grown by the modified liquid phase
epitaxy (LPE) technique. Appropriate annealing treatment can efficiently eliminate Sb vacancy and
stain which are formed during growing process, thus it is necessary to study the influence of annealing
condition (temperature, ambient, time and cooling rate) on the properties of InAsSb epilayer. The X-ray
diffraction measurement (XRD) showed the annealed InAsSb films were polycrystalline with
(111)-preferred orientation, except for the two samples annealed with 350 °C for 15 hours and with
rapid cooling rate, respectively, which exhibited a (100)-preferred orientation. The Fourier transform
infrared (FTIR) revealed a cut off wavelength more than 10 μm for the samples. Also, the infrared
transmittance would be improved due to decreasing of film defects by appropriate annealing treatment.
Measurement of electrical properties for samples revealed the increase of electron mobility and the
reduce of carrier concentration at 77K when keeping anneal temperature low at 350 °C and extending
anneal time, indicating the electrical improvement of the InAsSb layers.
The quasi-periodical quaternary ferroelectric Bragg reflectors were fabricated by using precursor solution with PEG
additive. For PZT, both PEG and PVP are suitable polymers in fabrication of periodical structures based on one single
chemical solution, while for BST the optical performance of the BST multilayers derived from the solution containing
PVP is better than that of the BST multilayers prepared using the PEG-containing solution. One or two defect layers
were inserted into the multilayers. The single cavity BST multilayer shows well-defined resonant cavity mode occurring
in the reflection stop band while the BST multilayer with double cavities exhibit two coupled cavity modes on the high
reflection band.
ZnTe crystal has been grown at a temperature as low as 1060°C using Te solvent method. X-ray diffraction showed that
the ZnTe crystals were grown from <110> oriented. The transmission was over 60% from 2 μm to 22 μm by using
Fourier Transform Infrared Spectrometer. The etch pit density in the sliced wafer was about 2×104 cm-2 detected by Scan
Electronic Microscopic. The transmission spectrums were measured from 0.2 to 3 THz by using Terahertz Time Domain
Spectroscopy. And the refractive index and extinction coefficient were obtained through analysis of the time domain
waveform.
GPS is already fully operational by America in orbit about the Earth, while the Galileo is not yet operational by E.U.. But
the user receiver equipment should be able to take advantage of both systems to increase accuracy, integrity, and overall
performance with as little impact on each other as possible. This paper presents the research and design on a hybrid
software-based GPS/Galileo receiver, together with the signal acquisition and tracking processing using a GPS/Galileo
software intermediate frequency (IF) architecture.
And the software-based integrated receiver architecture eliminates the traditional baseband ASIC and performs all digital
signal processing in software. This approach completely separates the analog signal conditioning (in hardware) and the
digital signal processing (in software), resulting in significant gain. So it will become increasingly important as new
signals from modernized GPS satellites become available and as the Galileo or China's BeiDou system starts operation.
Quantum dots, with functional group on surfaces, can be attached to bio-molecules to form quantum-dots/bio-molecule complex. With their excellent photo-electronic properties, quantum dots are now widely used to label the bio-molecules and highlight a cell's nucleus and microtubule fibers. They may also be used to control and operate the bio-molecules. We investigate the synthesis of the CdSe/ZnS core- shell quantum dots. To make the quantum dots water-soluble, the TOPO, TOPSe, and HAD ligands on the surface of CdSe/ZnS QDs were replaced by mercaptoundecanoic acid (MUA). The MUA-coated quantum dots are dispersible in water. For the use in biology, it is required that the quantum dots, when surrounded by a bio-environment, have high quantum yield and long fluorescence lifetime. Our study indicates that quantum yield of the core-shell quantum dots exceeds 60% and fluorescence lifetime of the electrons in the excited state is around 20 nano seconds. The CdSe/ZnS core/shell structure is very stable. No significant fluorescence decay is observed with a prolong excitation by a 365 nm ultro-violet light source of 30 mW. Here the function of the ZnS is two-fold: as both the barrier and the passivation layer for the CdSe quantum dots. In addition, the S-2 bonds are bio-active, which form stable bonding to bio-molecules.
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