Comparative study of the tropospheric ozone derived from satellite data using different interpolation techniques

Tropospheric ozone (TO) has been derived from the Aura/Ozone Monitoring Instrument (OMI) and the Aura/Microwave Limb Sounder (MLS) over the Indian sub-continent region using a tropospheric ozone residual (TOR) technique. The TO was initially retrieved at a horizontal spatial resolution following that of the Aura/MLS (300 km), which has a lower horizontal spatial resolution than that of the Aura/OMI (25 km). To overcome the limitations imposed by data at a lower spatial resolution, we have introduced a 2D rectangular interpolation (RI) algorithm for effective resampling of data to higher horizontal spatial resolutions. The performance of this algorithm has been evaluated by comparison against existing standard techniques such as nearest neighbourhood (NN) and kriging interpolation as well as comparison against in situ ozonesonde observations. Gridded TO estimates were subsequently generated for the region of interest at 25, 50, and 100 km horizontal spatial resolutions for further study.     

Artificial intelligence based optimization for vibration energy harvesting applications

This paper deals with optimization studies based on artificial intelligence methods. These modern optimization methods can be very useful for design improving of an electromagnetic vibration energy harvester. The vibration energy harvester is a complex mechatronic device which harvests electrical energy from ambient mechanical vibrations. The harvester design consists of a precise mechanical resonator, electromagnetic converter and electronics. The optimization study of such complex mechatronic device is complicated however artificial intelligence methods can be used for set up of optimal harvester parameters. Used optimization strategies are applied to optimize the design of the electro-magnetic vibration energy harvester according to multi-objective fitness functions. Optimization results of the harvester are summarized in this paper. Presented optimization algorithms can be used for a design of new energy harvesting systems or for improving on existing energy harvesting systems.     

Evolutionary topology optimization of periodic composites for extremal magnetic permeability and electrical permittivity

This paper presents a bidirectional evolutionary structural optimization (BESO) method for designing periodic microstructures of two-phase composites with extremal electromagnetic permeability and permittivity. The effective permeability and effective permittivity of the composite are obtained by applying the homogenization technique to the representative periodic base cell (PBC). Single or multiple objectives are defined to maximize or minimize the electromagnetic properties separately or simultaneously. The sensitivity analysis of the objective function is conducted using the adjoint method. Based on the established sensitivity number, BESO gradually evolves the topology of the PBC to an optimum. Numerical examples demonstrate that the electromagnetic properties of the resulting 2D and 3D microstructures are very close to the theoretical Hashin-Shtrikman (HS) bounds. The proposed BESO algorithm is computationally efficient as the solution usually converges in less than 50 iterations. The proposed BESO method can be implemented easily as a post-processor to standard commercial finite element analysis software packages, e.g. ANSYS which has been used in this study. The resulting topologies are clear black-and-white solutions (with no grey areas). Some interesting topological patterns such as Vigdergauz-type structure and Schwarz primitive structure have been found which will be useful for the design of electromagnetic materials.     

Simulation and design of MIM nanoresonators for color filter applications

We simulated metal–insulator–metal (MIM) nanoresonator structures that can be realized by sandwiching an insulator layer between two metal grating layers with subwavelength periods and heights. Simulation results indicate that it is possible to use relatively low refractive index polymeric materials as the insulator layer and such MIM structures can function as color filters with reasonably narrow bandwidths in transmission mode. Such color filters being superior in performance might find application in liquid crystal display devices replacing the conventional color filters. Simulations suggest that development of plasmonic modes at the metal–insulator interfaces might be responsible for the filter‐like transmission behavior of such structures. The transmission peaks can be tuned by changing the heights of the two grating layers and the refractive index of the insulator layer. Transmission peak is red‐shifted as insulator layer refractive index increases. Simulations were carried out using a home‐grown, monochromatic version of recursive convolution finite‐difference time‐domain method.     

标刻在金属零件上的二维条码识别

直接零件标识(DPM)技术是实现产品标识的重要手段,二维条码技术是其关键技术之一。DPM标识是以金属作为背景用激光在其上面打上二维条码,与印刷品上的二维条码识读相比,基于金属背景下的二维条码识读更为复杂。改进了传统的识别方法,综合运用最大连通域提取、改进的霍夫变换定位边界、基于最大匹配度的网格化分和基于灰度图像的无损信息提取等方法来实现条码图像的粗定位、精定位、校正、条码分割和数据提取。实验表明,本方案对于磨损、轻度污染、畸变及光照不均的金属上的二维条码图像的识读具有较强的抗干扰性,并取得可靠的识读结果。     

基于神经网络的金属断口3维重建

金属断口SEM图像的3维重建能更精确地定量分析断口,因而在材料断裂研究中具有重要意义。为了对金属断口SEM图像进行重建,根据金属断口表面具有的分形特征,提出了以高度z连续作为约束条件,利用神经网络对单幅断口SEM电镜图像进行重建的算法,并在实验中取得很好的重建效果。该算法对于未知光源方向的粗糙表面的3维重建具有较大的理论价值和实用价值。     

Metamaterial band theory： fundamentals ＆ applications

Remarkable progress has been made over the past decade in controlling light propagation and absorption in compact devices using nanophotonic structures and metamaterials. From sensing and modulation, to on-chip communication and light trapping for solar cells, new device applications and opportunities motivate the need for a rigorous understanding of the modal properties of metamaterials over a broad range of frequencies. In this review, we provide an overview of a metamaterial band theory we have developed that rigorously models the behavior of metamaterials made of dispersive materials such as metals. The theory extends traditional photonic band theory for periodic dielectric structures by coupling the mechanical motion of electrons in the metal directly to Maxwell＇s equations. The solution for the band structures of metamaterials is then reduced to a standard matrix eigenvalue problem that nevertheless fully takes into account the dispersive properties of the constituent materials. As an application of the metamaterial band theory, we show that one can develop a perturbation formalism based on this theory to physically explain and predict the effect of dielectric refractive index modulation or metallic plasma frequency variation in metamaterials. Furthermore, the metamaterial band theory also provides an intuitive physical picture of the source of modal material loss, as well as a rigorous upper bound on the modal material loss rate of any plasmonic, metamaterial structure. This in turn places fundamental limits on the broadband operation of such devices for applications such as photodetection and absorption.     

New scheme of the Discrete Sources Method for investigation of a near field enhancement by coupled particles

Numerical scheme of the Discrete Sources Method has been modified to examine near fields for the polarized light scattering by two coupled noble metal particles. The new scheme enables to compute a near field enhancement of several orders with high accuracy degree. The developed computer model has been employed to investigate plasmonic resonance of two prolate spheroids. Both the electric field intensity between coupled particles and the Scattering Cross-Section have been examined versus particle distance and particles aspect ratio.     

Transformation optics‐based horn antenna for focusing orbital angular momentum beams

In this article, a transformation optics (TO)‐based orbital angular momentum antenna is presented. By applying the coordinate transformation, the electromagnetic wave can be arbitrarily manipulated. A TO‐based horn antenna working at 5 GHz is designed. The simulation results show that by adopting the proposed TO‐based filling, the main lobe angle is reduced by 4° and the maximum gain is improved by 6.4 dB. At the same time, the proposed horn antenna has high aperture efficiency.     

A single sided dual‐antenna structure for UHF RFID tag applications

In this article, a dual‐antenna structure is presented for UHF RFID tag. The proposed structure is made of two L‐shaped strip antennas along with a cross‐shaped slot loaded patch. One antenna is exclusively used for receiving and harvesting full energy with complex conjugate of tag chip, whereas another used as backscatter to enhance maximum differential radar cross section with purely real input impedance, which results in the enhancement of read range. Further, electromagnetic band gap structure is used around the dual‐antenna structure to increase the gain which results in improved read range. The proposed antennas are fabricated and the S‐parameters are measured with the help of differential probe technique. Simulation and measurement results are found in good agreement. The performance of the proposed antenna is also investigated when it placed on different materials such as metal, wood, glass, and plastic. The study shows that the read range of antenna increases considerably when it is mounted on a metallic surface, while the maximum performance is observed when the antenna is attached on a glass surface with highest relative permittivity. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:619–628, 2015.     

Electromagnetic vibration energy harvesting device optimization by synchronous energy extraction

This paper investigates a new application of nonlinear techniques for vibration energy harvesting. The Synchronous Electric Charge Extraction (SECE) energy harvesting technique for piezoelectric generators is extended and adapted to electromagnetic generators. This new circuit, which is the dual of the SECE circuit, is named SMFE for Synchronous Magnetic Flux Extraction. A theoretical model is developed, and the harvested power is simulated. Comparisons with a classical energy extraction approach show that between 2.5 more power and 10% less power can be harvested, depending on the generator characteristics. It also allows the maximum power to be harvested whatever the value of the load. Finally, the SMFE circuit was embedded and tested on a simple centimeter-scale electromagnetic harvester. Measurements confirm the theoretical operating principle of the circuit.     

Inverse and direct magnetic shaping problems

In this work, we study the direct and inverse problems arising from electromagnetic shaping in applications such as continuous casting processes. The magnetic field produces a surface pressure which forces a molten metal to change its shape until it reaches an equilibrium state between the magnetic pressure and the surface tension. The arising direct problem is a free boundary problem which is to determine the shape of molten metals for a given magnetic field. On the other hand, the inverse problem is to seek a configuration of electromagnetic field generators (i.e. inductors) in order that molten metals have prescribed shapes. A level set method will be presented to determine an equilibrium shape formed by a given configuration of magnetic fields. Also a computational method as well as uniqueness results for the inverse problem will be introduced and illustrated with examples.     

标刻在金属零件上的二维条码数据提取方法

针对金属零件上二维条码光照分布不均、点扩散、对比度低与污染干扰等问题,提出一种基于原灰度图像小区域相邻模块对比提取二维条码数据的算法.首先通过峰度值排序法及模块区域微调法由粗到精定位每个二维条码模块位置,然后基于原灰度图像利用遗传算法提取二维条码的数据信息,得到最终的提取结果.与传统二维条码数据提取算法的实验结果证明,该算法对于复杂金属背景上的二维条码识读具有更高的可靠性.     

基于磁流变阻尼器的自供能无线传感系统设计

为检测磁流变阻尼器的内部状态参数,提出一种电磁式机械能量采集器的新型结构,将磁流变阻尼器工作缸内活塞运动的机械能转换为电能,以超级电容器作为储能器件,设计了相应的能量管理电路,实现温度传感器和无线传感模块的能量供给。实验结果表明:自供能装置能产生高达4.5 V的开路电压,所设计的能量管理系统可以驱动无线传感模块正常工作。     

Investigation of plasmonic whispering gallery modes of graphene equilateral triangle nanocavities

In this paper, a graphene-based equilateral triangle nanocavity is proposed and numerically investigated. The relationship between the mode characteristics and the nanocavity parameters, such as the geometry of nanocavity and the chemical potential of graphene, is systematically explored. A high-order plasmonic WGM (whispering gallery mode) with a high quality factor of 147.93 is obtained in our nanocavity with a wavelength of around 1.415 µm in free space, with a corresponding Purcell factor as high as 7.067 × 10⁸. The proposed plasmonic WGM nanocavity could be a key component of the high density plasmonic integrated circuits due to its ultra-compactness and performances.     

Quantum state manipulation of dipole emitters with a plasmonic double-bar resonator

We demonstrate efficient processes of entanglement generation and quantum state transfer (QST) with dipole emitters coupled to a plasmonic double-bar resonator. The bipartite and multipartite maximal entanglement and complete QST can be deterministically achieved by selecting appropriate coupling strength between individual emitters and the resonator mode. Moreover, the entanglement dynamics show that high fidelities of entanglement generation and QST can be realized even under imprecise coupling strength and the system decay. The feasibility analysis and practical implementation are discussed, which manifest that our schemes may be meaningful for exploring solid-state quantum information processing with the metal plasmonic mode.     

Light field morphing using 2D features

We present a 2D feature-based technique for morphing 3D objects represented by light fields. Existing light field morphing methods require the user to specify corresponding 3D feature elements to guide morph computation. Since slight errors in 3D specification can lead to significant morphing artifacts, we propose a scheme based on 2D feature elements that is less sensitive to imprecise marking of features. First, 2D features are specified by the user in a number of key views in the source and target light fields. Then the two light fields are warped view by view as guided by the corresponding 2D features. Finally, the two warped light fields are blended together to yield the desired light field morph. Two key issues in light field morphing are feature specification and warping of light field rays. For feature specification, we introduce a user interface for delineating 2D features in key views of a light field, which are automatically interpolated to other views. For ray warping, we describe a 2D technique that accounts for visibility changes and present a comparison to the ideal morphing of light fields. Light field morphing based on 2D features makes it simple to incorporate previous image morphing techniques such as nonuniform blending, as well as to morph between an image and a light field.     

电磁感应通信影响因素研究

论文对电磁感应通信的原理进行了分析,针对电磁感应通信的电源电压、传输距离、导磁环境等影响因素进行了试验研究,通过试验结果的分析得出电源电压、传输距离和导磁环境的影响存在一定的规律,而电磁环境、人因工程等则具有随机性.在电磁感应通信过程中,应充分考虑这些影响因素,并利用特定影响因素的规律,提高收发模块的通信可靠性.     

端到端通信中基于时间转换能量采集的计算迁移方案

在端到端（D2D）通信网络中,为提高移动云计算的有效性,提出了一种基于时间转换能量采集的计算迁移方案。首先,一个流量受限的智能移动终端把其需要迁移的计算任务通过D2D通信以射频信号的形式发送给一个能量受限的智能移动终端,后者利用时间转换方案对接收信号进行能量采集。然后,能量受限终端会为流量受限终端中继任务到云端服务器付出额外的流量消耗。最后,所提的方案被建模为一个最小化终端能量与流量消耗的非凸优化问题,通过优化能量受限终端的时间转换因子、采集能量分配因子以及流量受限终端的传输功率,最终获得了最优方案。仿真结果表明,相比于非协作方案,所提方案通过互惠协作进行计算迁移能有效地减少终端的匮乏资源开销。     

结合红外传感器的室内输电线路老化监测系统

本文针对目前老旧房屋建成使用年份较早,线路老化十分严重,极易引发电气火灾的现状,结合可见光传感器、红外传感器和电磁感应装置,设计了一套室内输电线路热老化监测系统.电磁感应装置用于探测墙体内输电线缆的位置,红外传感器采用多点测温的方式监测墙体内导线或配电箱内导线的温度,可见光传感器用于监测点视频监控和对异常部位拍摄照片.如果发现数据异常等问题,本装置通过以太网通信模块将异常数据和照片传输至上位机.用户可以通过手机APP或PC客户端查看当前监测点温度、当前监测点实时视频监控和设置温度及电磁力阈值.一旦监测温度和电磁力数据超过阈值,系统将发出线路老化预警,用户可以收到手机APP和PC客户端的报警推送和异常部位的图片信息,及时处理老化线缆,避免因线路老化引发电气火灾.