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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - A Novel Band-Notched UWB Conformal Antenna Combined with the Method of Circuitry
摘要： A real-time latching controller with consideration of wave force prediction is developed and applied to a heaving point-absorber to maximize its energy absorption. The control scheme is based on the combination of optimal command theory and first order-one variable grey model GM(1,1). By forecasting the wave forces in the near future, the control action at the next instant is deduced. Simulation results show that the energy absorption is increased due to the real-time controller. Therefore, the developed real-time controller is applicable to an industrial wave energy converter (WEC) in random waves. The effect of wave force prediction deviation is also examined. It is shown that the control efficiency is reduced in the presence of prediction deviation.
关键词： wave energy converter,wave force prediction,renewable energy,optimal command theory,energy absorption,real-time latching control
更新于2025-09-23 15:23:52
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Performance Analysis of a Solar-Powered Multi-Effect Refrigeration System
摘要： The main objective of the current work is to investigate the thermodynamic performance of a novel solar powered multi-effect refrigeration system. The proposed cycle consists of a solar tower system with a heliostat field and central receiver (CR) that has molten salt as the heat transfer fluid, an absorption refrigeration cycle (ARC), an ejector refrigeration cycle (ERC), and a cascade refrigeration cycle (CRC). Energy and exergy analyses were carried out to measure the thermodynamic performance of the proposed cycle, using Dhahran weather data and operating conditions. The largest contribution to cycle irreversibility was found to be from the CR system (52.5%), followed by the heliostat field (25%). The first and second-law efficiencies improved due to the increase in the following parameters: ejector evaporator temperature, turbine inlet and exit pressures, and cascade evaporator temperature. Parametric analysis showed that the compressor delivery pressure, turbine inlet and exit pressures, hot molten salt outlet temperature, and ejector evaporator temperature significantly affect the refrigeration output.
关键词： triple effect,refrigeration,ejector,cascade,solar energy,absorption
更新于2025-09-23 15:22:29
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Evaluating impact damage to fabric-based personal armor by infrared NDT
摘要： The paper considers the thermo-mechanical mechanism of interaction between the damage agents and armor protection made of polymer fabrics. A simplified mathematical model is proposed to describe the deceleration of a damage agent within an armor fabric due to the dissipation of energy expended on irreversible stretching deformations of fabric fibers, as well as fiber slipping friction and material heating. Woven fabric layers are replaced by solid layers characterized by averaged stiffness and viscosity. A discrete numerical model of a solid material is proposed to reduce a problem with a finite number of degrees of freedom; motion equations are obtained on the basis of the Lagrange equations of the second kind, and for their integration, a stable non-conservative difference scheme is used. The software implementation is based on a functional-object paradigm which allows the modeling of conjugated processes. The parameters of governing equations are identified by using the experimental data. Some illustrative examples of interaction between damage agents and armor barriers with different arrangement of fibers are presented. The proposed model can be used to predict the quality of armor protection with the changing number and location of fibers, as well as to test the armor protection by applying the technique of infrared thermography.
关键词： Armor protection,mathematical model,irreversible deformation,infrared thermography,energy absorption,numerical scheme,composite material,fiber friction
更新于2025-09-23 15:22:29
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Ultrafast energy absorption and photoexcitation of bulk plasmon in crystalline silicon subjected to intense near-infrared ultrashort laser pulses
摘要： We investigate the non-linear response and energy absorption in bulk silicon irradiated by intense 12-fs near-infrared laser pulses. Depending on the laser intensity, we distinguish two regimes of non-linear absorption of the laser energy: for low intensities, energy deposition and photoionization involve perturbative three-photon transition through the direct bandgap of silicon. For laser intensities near and above 1014 W/cm2, corresponding to photocarrier density of order 1022 cm?3, we find that absorption at near-infrared wavelengths is greatly enhanced due to excitation of bulk plasmon resonance. In this regime, the energy transfer to electrons exceeds a few times the thermal melting threshold of Si. The optical reflectivity of the photoexcited solid is found in good qualitative agreement with existing experimental data. In particular, the model predicts that the main features of the reflectivity curve of photoexcited Si as a function of the laser fluence are determined by the competition between state and band filling associated with Pauli exclusion principle and Drude free-carrier response. The non-linear response of the photoexcited solid is also investigated for irradiation of silicon with a sequence of two strong and temporary non-overlapping pulses. The cumulative effect of the two pulses is non-additive in terms of deposited energy. Photoionization and energy absorption on the leading edge of the second pulse is greatly enhanced due to free carrier absorption.
关键词： bulk silicon,optical reflectivity,photoexcited solid,near-infrared laser pulses,Drude free-carrier response,non-linear response,energy absorption,plasmon resonance
更新于2025-09-23 15:21:01
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Laser 3D printed bio-inspired impact resistant structure: failure mechanism under compressive loading
摘要： This work presents a comprehensive failure mechanism study of the bi-directionally corrugated (DCP) structures inspired by the telson of mantis shrimp. The DCP structures were fabricated by selective laser melting (SLM) with AlSi10Mg powder. The influence of key structural parameters, namely wave number (N), on the compressive behaviours, stress distribution, deformation modes and fracture mechanism of SLM-processed DCP components was systematically investigated. Results revealed that with the increase of wave number (N), the structural expansion effect became more obvious, which led to the disappearance of the plateau region on the compressive force-displacement curve, the decrease of specific energy absorption (SEA) growth rate and the energy absorption per periodicity cell. Three deformation modes were observed, namely full-folded mode (N = 4), transitional mode (N = 5), and global-buckling mode (N = 6). Finally, the fracture morphologies elucidated that the fracture mechanism changed from ductile fracture to brittle fracture with the increase of wave number.
关键词： bi-directionally corrugated panel,failure mechanism,selective laser melting,energy absorption,Bio-inspired
更新于2025-09-16 10:30:52
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Influence of surface plasmon polaritons on laser energy absorption and structuring of surfaces
摘要： The accurate calculation of laser energy absorption during femto- or picosecond laser pulse experiments is very important for the description of the formation of periodic surface structures. On a rough material surface, a crack or a step edge, ultrashort laser pulses can excite surface plasmon polaritons (SPP), i.e. surface plasmons coupled to a laser-electromagnetic wave. The interference of such plasmon wave and the incoming pulse leads to a periodic modulation of the deposited laser energy on the surface of the sample. In the present work, within the frames of a Two Temperature Model we propose the analytical form of the source term, which takes into account SPP excited at a step edge of a dielectric-metal interface upon irradiation of an ultrashort laser pulse at normal incidence. The influence of the laser pulse parameters on energy absorption is quantified for the example of gold. This result can be used for nanophotonic applications and for the theoretical investigation of the evolution of electronic and lattice temperatures and, therefore, of the formation of surfaces with predestined properties under controlled conditions.
关键词： Laser energy absorption,Surface plasmon polaritons,Plasmonics,LIPSS,Ultrashort laser pulses
更新于2025-09-11 14:15:04
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Murine <i>vs</i> human tissue compositions: implications of using human tissue compositions for photon energy absorption in mice
摘要： To investigate the implications of using human tissue compositions for dose calculations in mice for kilovoltage photon beams. Dual energy CT (DECT) images of 9 female mice were used to extract the effective atomic number Zeff and the relative electron density ρe for each voxel in the images. To investigate the influence of the tissue compositions on the absorbed radiation dose for a typical kilovoltage photon beam, mass energy-absorption coefficients μen/ρ were calculated for 10 different tissues in each mouse. Differences between human and murine tissue compositions can lead to errors around 7.5 % for soft tissues and 20.1 % for bone tissues in μen/ρ values for kilovoltage photon beams. When considering the spread within tissues, these errors can increase up to 17.5 % for soft tissues and 53.9 % for bone tissues within only a single standard deviation away from the mean tissue value. This study illustrates the need for murine reference tissue data. However, assigning only a single mean reference value to an entire tissue can still lead to large errors in dose calculations given the large spread within tissues of μen/ρ values found in this study. Therefore, new methods such as DECT and spectral CT imaging need to be explored, which can be important next steps in improving tissue assignment for dose calculations in small animal radiotherapy.
关键词： DECT,dose calculations,photon energy absorption,kilovoltage photon beams,spectral CT imaging,murine vs human tissue compositions
更新于2025-09-11 14:15:04