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This paper presents a pattern of ultra-wideband microstrip antenna with the compact size of 36 × 43mm2. The antenna is printed on an Arlon AD270 (tm) dielectric plate with a relative dielectric constant of 2.2, consisting of a flower-shaped radiation patch and a ground plane Through Ansoft HFSS simulation, the result shows that the impedance bandwidth operates from 3.3 to 11.0 GHz and the antenna...
The performance of SAA (Sense and Avoid) for UAV (Unmanned Aerial Vehicle) is the key function to ensure the UAV's autonomous flight safety. Due to the limitation of payload and size, the micro UAV can't equip large sensors such as radar, etc. Toward the challenging operation condition in low altitude flight environment, we proposed a complete stereo vision based SAA solution suitable for MUAV (Micro...
2-D (two-dimensional) reconstructing of the oil pipeline defect from MFL (magnetic flux leakage) signals is a difficult problem in MFL testing. The traditional solution is based on the neural network (NN) algorithm. But it has the disadvantages of complex structure, slow speed and low accuracy. To improve these disadvantages, a LS-SVM (least squares support vector machine) method is proposed for reconstructing...
In order to overcome the defects of traditional digital millivoltmeter, a kind of new digital display millivoltmeter based on STC89C52 is designed. The millivoltmeter consists of many integrated devices to realize signal transformation. It has many advantages, such as simplified the complexity of system design, enhanced anti-interference ability and accuracy, improved effectively the nonlinear and...
In this paper, the research for the design of a new three-phase 6/4 pole brushless doubly fed doubly salient permanent magnet (BDFDSPM) machine is presented. BDFDSPM machine has different scheme from normal doubly salient permanent magnet (DSPM) motor. BDFDSPM machine consists of two types of stator windings: the polyphase armature winding and the dc field winding, which the dc current flowing through...
Based on the principle of axial active magnetic bearing system with single degree of freedom, the difference between magnetic system vibration mode and the traditional bearing system vibration mode were described. Initial four order natural frequencies and vibration mode were calculated by the module of modal analysis of ANSYS11. Axial displacement and control current influence on natural frequencies...
Silicon carbide diodes are being pursued by the Army as a compact, power-dense replacement for silicon diodes in various applications. Diodes are typically needed to protect other circuit components from reverse voltages and currents. Improvements in micropipe density and manipulation of basal plane dislocations, along with increased wafer size, allow for fabrication of larger area silicon carbide...
Silicon carbide Super-GTOs are being pursued by the Army as a replacement for current silicon-based, high-power pulse switches. The devices discussed in this paper were designed and fabricated by Silicon Power and Cree and evaluated at the Army Research Laboratory. The chips were packaged in groups of four to create the first modules of silicon carbide Super-GTOs. Each switch module contains four...
In this paper, for the first time, large area SiC BJTs were fabricated on SiC wafers with reduced Basal Plane Dislocations (BPDs). We have demonstrated: (1) stable performance on 1200 V, 20 A SiC BJTs after long duration of electrical stress at different current densities up to 150 A/cm2; (2) a blocking yield of >80% with low leakage current (<20 nA at 1800 V) on 3" wafers along with current...
There has been a rapid improvement in SiC materials and power devices during the last few years. SiC unipolar devices such as Schottky diodes, JFETS and MOSFETs have been developed extensively and advantages of insertion such devices in the power systems have been demonstrated. However, for high power systems such as high voltage converters, bipolar devices are preferable due to their low on-resistance...
This paper discusses the recent progress in large area silicon carbide (SiC) DMOSFETs and junction barrier Schottky (JBS) diodes. 1.2 kV and 10 kV SiC DMOSFETs have been produced with die areas greater than 0.64 cm2. SiC JBS diode dies also rated at 1.2 kV and 10 kV have been produced with die areas exceeding 1.5 cm2. These results demonstrate that SiC power devices provide a significant leap forward...
Recent advancement in computer hardware and software have led to an increasing amount of 3D models. Furthermore, the rapid development of WWW enables the access to 3D models constructed by people all over the world. This paper surveyed the background, state-of-the-art review and progress of content-based 3D shape retrieval, and analyzed and described several topics, including the preprocessing, coordinates...
SiC power bipolar junction transistors (BJTs) are believed to have the potential of operating reliably at much higher junction temperatures as compared to SiC MOSFETs. The obstacle for commercialization of SiC BJTs is the presence of degradation in both on-resistance and current gain, first detected by Agarwal et al. The recombination-induced stacking faults (SFs) were a prime suspect but no clear...
Rapidly improving 4 H-SiC material quality and a maturing MOS process/design have enabled the development of the largest 10 kV MOSFET to date and the first 10 kV n-IGBT capable of flowing 10 A and 4 A, respectively, with very low on- resistances. With 20 V on the gate, both devices have aVp~ 5V with a positive temperature coefficient for on-resistance that facilitates their use in a parallel configuration...
For the first time, the integration of 1200V SiC BJT with two types of SiC diode, PiN and MPS diode is designed, fabricated and characterized. Compared with the discrete anti-parallel diode, the integration solution will reduce the cost, size and packaging parasitic. The static characteristics show competitive BJT and diode performance in the integrated device as compared to discrete devices. The...
Degradation in both current gain and specific on-resistance of fabricated 4H-SiC BJTs have been observed after a short period of operation. In this paper, 1200 V BJTs were stressed and factors that cause the degradation are proposed. The degradation may be attributed to the increase of the surface states density along the SiC/SiO2 interface, which results in an increased surface recombination current...
This paper describes the software and hardware platform of signal generator for smart antenna system. The purpose of developing this generator is to verify the performances of DOA and DBF in smart antenna system. It is used to simulate the signals received by the antenna array. Finally, the generator was implemented based on mixed signal processing techniques. And the whole are controlled by FPGA.
Nowadays, digital beam forming (DBF) technology is more and more widely used in communication and radar systems. But in most situations, lots of errors such as the array position uncertainty or RF channel dissimilarity, A/D sampling deviation, etc., usually make the actual result deviated from the theory analysis. In this paper, firstly, the effects caused by these uncertainties are illustrated, then...
A novel simulation testbed based on HILS (hardware-In-the-loop simulation) technology is described for space-time signal processing in a TDMA anti-jamming smart antenna receiver system. The testbed serves the space-time signal processor as a powerful and effective tool in its verification and debugging. The function and target of the simulation testbed is analyzed first. The architecture of this testbed...
In this paper, we present a novel method called PSO to design the coupled transmission line filter for UWB system. After detailed theoretical analysis and numerical simulation, parameters of layout for UWB coupled transmission line filter are given. Then, it was implemented on PCB. The simulation and measured results showed that, as a kind of novel optimization method, PSO is proven to be very effective...
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