Design of a Dual-Band Sectoral Antenna for Hiperlan2 Application Using Double Layers of Metallic Electromagnetic Band Gap (M-EBG) Materials as a Superstrate

A novel design of a sectoral antenna that utilizes a double layer Metallic Electromagnetic Band Gap (M-EBG) as a superstrate for dual band directivity enhancement is presented in this paper. We obtain the different operating frequencies by adjusting the distance of the lower M-EBG layer from printed patch antenna and also the height between upper and lower M-EBG layers. This antenna operates according to a sectoral radiation pattern form presenting a half power beamwidth of at least 60∘. The proposed structure presents more than 17 dB directivity enhancement at 5.25 GHz and 5.65 GHz as compared to those of a patch antenna with 9 dB directivity. The principle is explained and applied to a Hiperlan2 antenna

Self-Powered Wireless Sensing for Smart Infrastructure

Effective sensing of environmental parameters or conditions rely on wireless connectivity of spatially distributed autonomous sensors to acquire and transmit data to a main location. To date, the majority of sensing and wireless transmission devices rely on wired connections or batteries that require periodic replacement, which is not entirely true to the concept of an autonomous embedded sensing network. Advances made towards the development of low-power microcontrollers, sensing devices and ultra low-power wireless technologies open the opportunity for substituting depletable batteries with low levels of locally-harvested kinetic, light, or thermal energy to power the sensing and transmission functions of a network. The predominant approach to using locally-harvested power has been to use an auxiliary harvester, solar or mechanical power, to operate vibration or ow sensing and transmission devices. In contrast, it would be more advantageous, in terms of size or volume of sensing element or in terms of availability of power, to use the same device to sense a physical quantity over a specific time period and to harvest energy that can be used to operate itself as a sensor and to power the transmission of the acquired signal over other periods. In this work, we will present examples of self-powered wireless sensors of air speed, water flow and vibrations

TREX1 is expressed by microglia in normal human brain and increases in regions affected by ischemia

BACKGROUND: Mutations in the three-prime repair exonuclease 1 (TREX1) gene have been associated with neurological diseases, including Retinal Vasculopathy with Cerebral Leukoencephalopathy (RVCL). However, the endogenous expression of TREX1 in human brain has not been studied. METHODS: We produced a rabbit polyclonal antibody (pAb) to TREX1 to characterize TREX1 by Western blotting (WB) of cell lysates from normal controls and subjects carrying an RVCL frame-shift mutation. Dual staining was performed to determine cell types expressing TREX1 in human brain tissue. TREX1 distribution in human brain was further evaluated by immunohistochemical analyses of formalin-fixed, paraffin-embedded samples from normal controls and patients with RVCL and ischemic stroke. RESULTS: After validating the specificity of our anti-TREX1 rabbit pAb, WB analysis was utilized to detect the endogenous wild-type and frame-shift mutant of TREX1 in cell lysates. Dual staining in human brain tissues from patients with RVCL and normal controls localized TREX1 to a subset of microglia and macrophages. Quantification of immunohistochemical staining of the cerebral cortex revealed that TREX1 CONCLUSIONS: TREX1 is expressed by a subset of microglia in normal human brain, often in close proximity to the microvasculature, and increases in the setting of ischemic lesions. These findings suggest a role for TREX

Measurement of Nonlinear Receptivity to Surface Irregularities

Acoustic receptivity is the process by which acoustic disturbances are internalized into the shear layer to generate instability waves. Experiments have shown that, when tuned to the eigenvalue modes, the amplitude of the resulting T-S waves scales with the acoustic field intensity. When a surface irregularity is present, the characteristic wall wavenumber forces a spatial mode onto the near-wall mean velocity field, thus providing modal length scales comparable to those of T-S waves. In this experiment an attempt was made to increase the acoustic receptivity by exciting a difference mode via a quadratic interaction between two larger-wavenumber, forced modes. The difference mode is tuned to the dominant T-S eigenmode wavenumber. As expected, an increased receptivity corresponding to the difference mode was measured downstream of branch I, suggesting the presence of the nonlinearity

Multi-Fidelity Modeling and Simulation of Wave Energy Converters

Equations governing the response of wave energy converters (WECs) consist of partial differential equations and nonlinear boundary conditions that model the wave absorption, which is commonly used for classification of WECs, wave radiation and diffraction as required for prediction of wave energy generation by WEC farms, the converter’s response and the transduction mechanism. To date, the modeling and simulation of WECs or WEC arrays are based on linear wave theory, which assumes irrotational flow and limits the analysis for design to small wave amplitudes. In contrast, it is desirable to operate WECs in large waves under resonance conditions that would lead to large amplitude motions for effective energy conversion. With large amplitude waves and motions or responses, the linear and irrotational flow assumptions would not be valid. In this talk, we present a review and examples of (1) physics-based multi-fidelity modeling and simulation procedures that could be performed to develop effective control and optimization strategies for different types of WECs, and (2) nonlinear phenomena that can be exploited to enhance the performance of WECs

Homogenization of dislocation dynamics

In this paper we consider the dynamics of dislocations with the same Burgers vector, contained in the same glide plane, and moving in a material with periodic obstacles. We study two cases: i) the particular case of parallel straight dislocations and ii) the general case of curved dislocations. In each case, we perform rigorously the homogenization of the dynamics and predict the corresponding effective macroscopic elasto-visco-plastic flow rule