Materials Literature
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Fiberglass composites with three dimensionally varying dielectric properties have been created using a novel dry powder dot deposition system. The out of plane and in plane effective properties were previously determined empirically with separate methods. This work establishes an analytic effective media approach to c…
The effects of geometry modulation applied to a periodic structure built in stripline technology are assessed by means of the dispersion diagrams calculated in the spectral, or k, plane by using a commercial electromagnetic eigenmode solver. Modifications of surfaces representing propagation modes, of electromagnetic…
This contribution presents the design of a low pass filter LPF with wide rejection based on modified complementary single split ring resonator (CSRR). The CSRRs are etched on the back side of the transmission and connected by slot line to achieve the desired resonance frequency. The quasi-static resonance of the CSRRs…
The CdCl2heat treatment (HT) is one of the most critical steps in the fabrication of high efficiency CdTe solar cells. In this study a laser based CdCl2treatment is presented. A high power near infrared (808 nm) diode laser was used for laser annealing (LA) CdTe cells. The effect of laser power density (LPD) and annea…
This paper describes the design and behavior of a Fabry-Perot Cavity (FPC) antenna system with split beam in the near-field and decreased beamwidth of the far-field pattern. The FPC antenna system is a coplanar waveguide (CPW)-fed slot antenna with 9 × 27 rectangular aperture unit cells in the frequency selective surf…
We present the design and concept of 3-dimensional (3-D) electromagnetic energy collection for microwave energy harvesting. We show that by vertically stacking panels of electromagnetic energy collectors, the power collected experiences a significant enhancement over a single 2-D panel. Here, we present an example of…
A circularly symmetric high impedance surface is used as ground plane for spiral antennas. It is shown through simulations that a circular high impedance surface exhibits a wider operational bandwidth when used as ground plane for this type of radiators compared to loop antennas.
A novel spherical spiral metamaterial unit cell is presented. The structure is shown to provide negative permeability over a 31.7% bandwidth at one orientation with respect to the incident electric field, negative permittivity over a 40.4% bandwidth at a second orientation, and double-negative behavior over a 15.5% ba…
Quasi-conformal transformation optics (QCTO) is applied to design electromagnetic lenses for focusing and collimating applications at microwave frequencies. Two devices are studied and conceived by solving the Laplace's equation that describes the deformation of a medium in a space transformation. The first lens is ap…
This paper proposes a 1-bit linearly polarized reconfigurable transmitarray element with double-layer square slots. The theory for the cascaded 2-layer transmitarray element is presented first, and a dielectric thickness corresponding to a 30° phase delay is suggested as the layer separation in order to get a 180° pha…
본 연구에서는 항공우주, 유도탄, 자동화 산업에 널리 적용되는 금속복합화약 ZPP(Zirconium Potassium Perchlorate)의 제조공정 과 특성평가를 고찰하였다. 기본적으로 PMD에 사용되는 고체 점화제는 금속연료와 산화제 그리고 유기 고분자물질(결합재)로 구성되며, 이들 원료들을 균질하게 혼합하기 위하여 precipitation process를 사용하였다. 원료 물질의 특성 및 열적 반응 해석을 통한 최적 조성비를 설계하였으며, 이들의 입도, 형상, 열량 분석 등의 특성 평가를 수행하여 결과를 비교하였다. This research investiga…
Abstract The aim of the study was to produce heterophasic graphene nanoplatelets based formulation designed for ink-jet printing and biomedical applications. The compositions should meet two conditions: should be cytocompatible and have the rheological properties that allow to apply it with ink-jet printing technique.…
The details of the special three-dimensional micro-nano scale ripples with a period of hundreds of microns on the surfaces of a Zr-based and a La-based metallic glass irradiated separately by single laser pulse are investigated. We use the small-amplitude capillary wave theory to unveil the ripple formation mechanism…
고체로켓추진기관 연소관 내열고무의 열반응 특성을 평가하기 위한 모사시험장치를 개발하였다. 시험장치는 연소실 압력 2,500 psi, 연소시간 100 s까지 시험할 수 있으며, 여러 시편을 동시에 상대 비교 할 수 있다. 시편 부는 사각 패널로 되어 있으며, 마주보는 두 면에서는 연소시간 동안 시편 내부의 온도 변화를 측정할 수 있다. 시험장치의 안전성을 확인하기 위하여 연소실 유효평균압력 1,000 psi, 유효연소시간 10 s 시험을 수행하였으며, 내열고무의 열특성 분석에 필요한 기본 데이터들, 즉 연소실의 압력-시간 선도, 재료 내부에서의 온도-시간 선도, 재료…
This paper presents a sliding mode control strategy for a Hybrid Energy Storage System (HESS) with a semi-active capacitor configuration, applied to electric vehicles. The system consists of a battery bank and ultracapacitor (UC) connected through a high efficiency DC-DC converter which controls the energy exchange wi…
Plane wave scattering by a perfectly conducting strip grating is considered. A methodology for the computation of the induced currents is proposed, which utilizes the knowledge of the current induced in the center region of a truncated finite grating with only a moderate number of strips.
We designed an electronic nose to classify different Chinese liquors. Kernel entropy component analysis (KECA) was applied to reduce the dimensionality of data sets. In order to avoid the blindness of parameter setting, particle swarm optimization (PSO) algorithm was employed to optimize parameters in KECA. At last, w…
Mechanical gears are used extensively for low-speed electrical machine application to reach high system torque density. However, gear lubrication, vibration and reliability can be significant issues. Magnetic gears (MG) can effectively reduce the speed and amplify system output torque through modulation of ferromagnet…
Japanese R65 rail is metallographically analyzed after operation in the East Siberian Railroad. Its chemical composition complies with Technical Specifications TU 0921-239-01124323–2007 for the steel used in the production of 350LDT rail. The macrostructure of the metal is of satisfactory quality. The tensile mechanic…
Structural and dynamic analysis based on combined thermophysical and molecular-mobility measurements via spin-probe ESR spectroscopy has been applied to films