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The silicon carbide field emission array of microtips on the tops of micropedestals fabricated on original technology was embedded as cathode in planar vacuum diode and its CVC was characterized. The electron beams formed by the cathodes with various dimensions of micropedestals was numerically simulated. The results demonstrate significant influence of micropedestal dimensions on emission current...
Mathematical models of multi-tip field electron emitter are considered. Conception of the virtual cathode are used for the square packed array, and in the axial symmetry problem. The field enhancement factor was chosen as the measure of the emission system efficient. It is shown that the package parameter must be grater than doubled single tip length.
The array shape distortion effect on soft linear array Direction of Arrival (DOA) estimation performance was studied by theory analysis, simulation and field data process. The steering vector of beamforming algorithm was mismatched when array shape was distorted, then cause the line array direction performance degradation even failure. Our analysis based conventional beamforming(CBF) and adaptive...
Wall-climbing robot research is increasingly popular for cleaning, painting, and repairing high-rise buildings. In this study, a compliant wall-climbing robotic platform for various curvatures is presented. In order to adapt to flat and curved surfaces with a single configuration, the robotic platform uses a compliance mechanism with eight legs. A parallel four-bar linkage connects the inner frame...
In this work, an efficient method is proposed to calculate the miniband structure and density of states for well-ordered Ge/Si-nanodisk array. Within the envelop-function framework, our approach surmounts theoretical approximations of the multi-dimensional Kronig-Penney method and provides a guideline for three-dimensional quantum dots design by simulating the effect of the interdot space on miniband...
This paper proposes the design method of novel resonant elements with four axial symmetry designed by using the genetic algorithm(GA). Designing a reflectarray, it is desirable for the resonant element to have a low cross-polarization and dual-polarization property, in addition to providing an ideal reflection phase. Then, we verified effectiveness of the proposed elements from the radiation pattern...
Integrating legacy plant and process information into engineering, control, and enterprise systems may significantly increase the efficiency of managerial and technical operations in industrial facilities. The first step towards the pursued data integration is the extraction of relevant information from existing engineering documents, many of which are stored in vector-graphics-compatible formats...
Spatially focusing a wavefield (or better the corresponding intensity) into a target point is a canonical problem relevant both theoretically and practically. In this communication, after briefly reviewing some critical aspects of such a problem, we provide an update of some focusing approaches we have recently developed. Numerical results and comparisons are also reported.
Oil exploration mainly targets to the locations that are closed or below the salt bodies, in the underlying geologic structure. With time the computational tools which can help in interpreting, analysing and estimating the geometry with its position has been increased. But still at many time the data which is gathered using these computational tools is recognized with the lack of resolution and poor...
In this paper a planar leaky-wave antenna in a superstrate-like configuration is used to generate a cosecantsquared radiation pattern. As a difference with previous designs based on such configurations, the superstrate here is truncated. In this way an asymmetric illumination of the radiating aperture is achieved, thereby generating the required pattern. The antenna is fed by a waveguide open in the...
In this paper the Radon transform is used to study planar arrays. It is shown that the Radon transform (in its discrete version) and the associated projection-slice theorem define interesting relations between the array factor and the amplitude coefficients of a planar array. These relations are used to develop a synthesis procedure for 2D arrays that have a pencil beam shaped array factor with the...
The use of additive manufacturing (AM) techniques for the development of 3D frequency selective structures is discussed. The type of structures introduced use 3D printing to form the shape of the elements which are then coated with conductive paint. Fully and partially metalised array elements are studied. Fully metalised elements offer mechanically robust structures as well as reliability in the...
A method to reconstruct the excitation coefficients of wide-slot arrays from near-field data is presented. The plane wave spectrum (PWS) is used for reconstruction, and the shape of the field distribution on a wide slot is considered in the calculation of the PWS. The proposed algorithm is validated through the reconstruction of the excitation coefficients of a wide-slot array with element failures...
The square and rectangular shape of the pixels in the digital images for sensing and display purposes introduces several inaccuracies in the representation of digital images. The major disadvantage of square pixel shapes is the inability to accurately capture and display the details in the objects having variable orientations to edges, shapes and regions. This effect can be observed by the inaccurate...
In order to provide reliable knowledge about highly resolved directional properties of the radio propagation channel, straight forward beam-forming has been used in this study. Accurate measurement data based on an extreme size virtual antenna array (25×25×25 = 15625 elements) have been provided for an indoor scenario in both line of sight and non-line if sight conditions. The results indicate that...
We demonstrate the characteristics of multi-mode resonance in coupled resonators with multi-slots. Our results show that the multi-mode resonance is caused by the structural complicity of the multi-slot coupled resonators. Each resonance mode corresponds to each distribution of electric charges determined by the structural dimensions.
The performance of a photovoltaic (PV) array is affected by many factors, including its integration into a system. Without a maximum power point tracking (MPPT) algorithm, the PV array will operate at the voltage of its load, which often is not the maximum power point (MPP); therefore, causing the PV array to not produce its maximum power output. This paper discusses a current MPPT technique (Perturb...
As the scale of parallel computing systems grows, the importance of collective I/O also increases because it provides the function of single file based parallel I/O. Collective I/O follows two-phase I/O scheme that consists of a data exchange phase and an I/O phase. The previous studies of collective I/O were usually related with improving the performance of each phase. Especially, Heuristic Node...
The basic magnetic properties of patterned magnetic film have been attracting much interests due to their potential applications in magnetic random access memory (MRAM) and ultrahigh-density data storage devices [1], [2], [3]. Their magnetic properties closely depend on the size, shape and inter-element interactions, which have been reported extensively in the past 20 years. However, their researches...
Recently, integrated motor propulsors (IMPs) have been under extensive research and development because of the numerous advantages of underwater propulsion for vehicles, such as a simple, quiet, lightweight, and small-size structure [1]. IMPs require minimized torque ripple for smooth and quiet operation when used in undersea vehicles or unmanned submarines. Thus, torque ripple reduction should be...
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