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A two-scale model modified by improved geometrical optics (GO) is proposed. The improved geometrical optics considers the short waves diffraction and obtains the same accuracy as zero order Kirchhoff. Simulation shows that the modified two-scale model obtains satisfied accuracy as well as retains the simple representation in the frequency band which classical two scale model can not be applied. The...
We have developed a new back side fabrication process to actuate microshutter arrays (MSA) electrostatically at the NASA Goddard Space Flight Center. The microshutters are fabricated on silicon with thin silicon nitride membranes. The microshutters rotate 90° on torsion bars. The selected microshutters are actuated, held, and addressed electrostatically by applying voltages on the electrodes the front...
A modified antenna based on fractal split ring resonators (FSRRs) is presented. The antenna is composed of two layers of Teflon with a low permittivity (e=2.2). The inner and outer ring of FSRRS are connected with ground plane by two metal pins by which way the antenna is similarly to planar inverted-F antennas (PIFAs). The modified antenna with fractal split ring resonators (FSRRs) make the size...
With the increasing complexity of electromagnetic environment and increasing intensity of military confrontation, the potential security exposure in the application of satellite navigation has become one real threat to face. This paper has an analysis on GNSS repeater spoofing technique, for fake Position, fake Time and fake Velocity in theory. The analysis results of this paper will provide beneficial...
This paper describes the modeling, design and performance of 30 GHz low noise amplifiers (LNAs) integrated with slot antennas on GaAs monolithic microwave integrated circuits (MMICs). Various designs are compared, showing the tradeoffs between achievable noise figure, gain and overall chip size.
In this paper the basic concept of static characteristics is reviewed along with the major advantages and disadvantages of LCC and VSC in a multi-terminal configuration. The main objective of the paper is to describe the use of Static Characteristics to look at alternative control mode arrangements that could be utilised for multi-terminal operation and to assess the advantages and disadvantages of...
A lithographic VCSEL approach is used in GaAs-based VCSELs to eliminate the oxide aperture. Record low voltage drive and differential resistance are demonstrated.
Single mode lithographic VCSELs are shown to be capable of unprecedented dense packing into arrays for high pulse power to improve spectral control and beam quality.
The paper describes the combination of conductive, semi-transparent graphene films with a n-type silicon wafers to make solar cells with power conversion efficiencies up to 1.5% at AM 1.5G. The Schottky junction solar cells reported here can be extended to other semiconducting materials instead of silicon, in which graphene serves multiple functions as an active junction layer, charge transport path...
This paper presents a new flexible GMRES for solving surface integral equation (SIE). In the proposed method, JMCFIE is set as the inner iteration to accelerate the convergence speed, while PMCHWT is set as the outer iteration to guarantee the accuracy. In addition, multilevel fast mutilpole algorithm (MLFMA) is used to reduce the memory of impedance matrix and improve the computational efficiency...
3He gaseous detectors have been widely used for homeland security and neutron scattering applications. Due to the 3He supply crisis, different alternative thermal neutron detection techniques have been studied in recent years. And the boron coated straw tube detectors (BCSD) have been chosen as one of the potential replacements of 3He gaseous detectors for the adequate supply and large cross section...
The combination of a 3He proportional counter and a 4He proportional counter sharing the same parameters was employed as the low background thermal neutron detector. The wall material is oxygen-free copper for low surface a emit rate. Other characters including wall effect and energy resolution were also optimized for low background performance. A portable readout electronics system has been developed...
Modal properties of single mode lithographic VCSELs are studied for use in densely packed 2-D arrays for improved spectral control, improved beam quality, and high pulse power.
We propose the recent progress in fast integral multiscale simulations in our group in this contribution. Firstly, a wideband fast kernel independent fast solver is proposed. The equivalence sources on designed equivalence surface are introduced to obtain the nested low rank approximation. At the low to mid frequency, thanks to the nested low rank approximation, the computation complexity of the proposed...
In the field of radio astronomy, CLEAN algorithm is in constant development. In order to solve the problem of distortion of the image under some conditions, we propose a modified CLEAN algorithm, so that the result map is smooth and the resolution has been improved.
A compact one-section in-line band rejection structure is proposed. Figure 1 shows the circuit configuration of the proposed structure, it simply consists two transmission lines and with one of the transmission line serial connected with a reactive element jX. Using the basic circuit theory analyzing the proposed structure, a design equation is obtained for determining band rejection frequency. Varying...
With the aging population problem getting more and more aggravated, the number of hemiplegia patients increases rapidly, which results in the increasing requirement of rehabilitation training for regaining the body movement function. Taking advantages of rehabilitation robots makes the rehabilitation training more scientific and efficient compared to traditional rehabilitation measures such as manual...
With the aggravation of ageing society, the number of hemiplegic patients has increased rapidly. As a result, the requirement of rehabilitation training has made a huge increase. In order to help hemiplegic patients to get a better rehabilitation and help occupational therapists to reduce working pressure, series of rehabilitation training robot has been developed. Although the rehabilitation robot...
Up to now, with the increasing of the elderly population, more and more patients are suffering from hemiplegia. The needs for hemiplegic rehabilitation is increasing quickly. As traditional rehabilitation, each patient must be treated by therapist, one by one. However, because of the different levels of therapists, the rehabilitation cannot be performed as the as the same. Normally, the rehabilitation...
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