Numerical investigation has been made on a Linear Array of surface wave driven plasma monopole antenna using finite difference time domain simulation. Variations of the excitation power can be used for construction of a dynamically reconfigurable antenna. Plasma elements in the nominal pressure of 0.4 mb are fed through an RF power at 500 MHz using an equal power divider. The results show that while the variations of the excitation power shift the Array resonant frequency between 50 MHz to 120 MHz, the Array gain and directivity remain approximately unchanged in the new resonant frequency. Since efficiency is critical to communication systems, the total efficiencies of the reconfigurable Array were analyzed from the least to the highest excitation power. The highest efficiency belongs to the Array which the separation between elements is a quarter of wavelength. Using this cutting edge technology in space application, it will be possible to transmit through an antenna in a multiple frequency avoiding interference between adjacent antennas.

This paper describes the synthesis of digitally excited pencil/flat top dual beams simultaneously in a Linear antenna Array constructed of isotropic elements. The objective is to generate a pencil/flat top beam pair using the excitations generated by the evolutionary algorithms. Both the beams share common variable discrete amplitude excitations and differ in variable discrete phase excitations. This synthesis is treated as a multi-objective optimization problem and is handled by Quantum Particle Swarm Optimization algorithm duly controlling the fitness functions. These functions include many of the radiation pattern parameters like side lobe level, half power beam width and beam width at the side lobe level in both the beams along with the ripple in the flat top band of flat top beam. In addition to it, the dynamic range ratio of the amplitudes excitations is set below a certain level to diminish the mutual coupling effects in the Array. Two sets of experiments are conducted and the effectiveness of this algorithm is proved by comparing it with various versions of swarm optimization algorithms.

The Array factor (sidelobe level, SLL) of a Linear Array is optimized using modified continuous genetic algorithms in this work. The amplitudes and phases of the currents as well as the separation of the antennas are all taken as variables to be controlled. The results of the design using modified GA versions are compared with other methods. Two design problems were studied using several continuous modified GA versions and the results are presented as several plots. As a final example, the design specifications for an Array with 200 elements are given. The effectiveness and advantages of the proposed modified GA versions are outlined.

Comparison of direct and indirect methods for georeferencing of satellite Linear Array stereo images is proposed in this paper. In direct method, colLinear condition and orbital elements are used for geolocation of pixels and ground control points (GCPs) are used in indirect method. After geolocation of initial points, a polynomial transformation is used to change pixels coordinates into corresponding geographical values. We validate these methods through experiment with SPOT-4 and IRS-P6 images. Experimental results indicate that indirect method can be used for georeferencing of satellite Linear Array images and the accuracy is as much as or even better than that of the direct method but it is time- and cost-consuming and also needs operator.

Background: External beam radiotherapy and brachytherapy plays a vital role in the management of cancer cervix. High dose rate brachytherapy is being presently used worldwide for the brachytherapy applica ons. At present, 2-Dimensional Linear Array detectors are the most common QA tool used for pretreatment pa ent specific quality assurance in external beam radiotherapy alone and  ll date no dedicated brachytherapy tool is available. An a$empt has been made to explore the feasibility of using 2 dimensional Linear Array, Imatrixx as a QA tool for brachytherapy. Materials and Methods: Reference treatment plans are generated by Plato treatment planning system using the images of Imatrix acquired with Siemens CT simulator. The efficacy of Imatrixx as a QA tool for intracavitary treatment plan verifica on, dwell posi on and dwell  me accuracy verifica on are studied. Results: The length and the widths along with the area of the reference isodose curves of the intracavitary treatment plans generated by Plato Planning system and measured with Imatrixx is compared. The difference in area of the reference isodose curve is found to vary from-0. 59 cm2 to 4. 59 cm2. The es mated user correc on factor for Iridium-192 energy, 0. 38 MeV is 1. 090 with a standard devia on of ± 0. 0211. Machine related QA such as dwell posi on and dwell  me were measured with Imatrixx with an accuracy of 0. 5 mm and 0. 02 s respec vely. Conclusion: Results shows that the 2-Dimensional Linear Array, Imatrixx can be used with accepted accuracy for both machine and pa ent specific quality assurance in brachytherapy treatments.

In recent years, high resolution push broom Linear Array satellite imageries have been attracted world wide attention more than before. This is due to the wealth of the radiometric and geometric information inherent in these images which provide valuable data for environmental analysis, natural disaster forecasting, response and management. However, to employ this technology for the preliminary rapid mapping requires much computational effort. There are basically two main approaches for the geometric correction of Linear Array push broom imageries. These are the so called generic and the rigorous mathematical models. The latter approach incorporates the physical rotations and 3D translations to generate the exterior orientation parameters of each scan line. This is due to the fact that these images have a dynamic geometry in the sense that each image line has its own exterior orientation parameters leading to a multi-projection image. Bearing in mind the narrow angle field of view of the high resolution Linear Array imageries and great number of unknowns in the equations, this approach requires additional auxiliary data for the solution of geometric rectification. The former approach on the other hand employs a rational polynomial function to relate the image and object points. This approach is usually referred to as the rational function model (RFM). However, this method also encounters complications: Fitting flexibility of the rational function model is dependent on the inclusion of the high order polynomial terms. Experimental tests have confirmed that 78 rational polynomials coefficients (RPCs) are quite sufficient for geometric correction of Linear Array imageries. The solution of these RPCs requires a great deal of field works for the measurement of the ground control points. Moreover, to prevent the ill-conditioning of the solution of the Linear equations, regularization and normalization are necessary. Complications of the solution of the RFM may be reduced by employing the direct Linear transformation (DLT) approach. The DLT model is in fact the RFM with only Linear terms. This approach has gained popularity due to its simplicity and requirement for small number of GCPs. Nevertheless, reducing the field work by limiting the number of GCPs is achieved by sacrificing the fitting accuracy of the RFM. The DLT approach is, therefore, unable to produce the optimum solution in the absence of the higher order terms. The accuracy of the DLT solution still further deteriorates in mountainous terrains due to the fact that the DLT model presupposes the relief and tilt displacement to be similar to the single projection frame type images. In this paper a new solution of the DLT model for the geometric handling of the Linear Array imageries is proposed. The proposed approach is based on transferring a Linear Array image into an equivalent virtual single projection image (VSPI). In this way the fitting capability of the classical DLT model when applied to the Linear Array type imageries, particularly in mountainous terrains, can be improved. The reason lies in the fact that the VSPI frame is generated by including the influence of the approximate height information. This makes the relief displacement in the satellite movement direction similar to the relief displacement in the scan line direction. In this paper the fitting defect of the DLT model for the push broom imagery is first proved mathematically. This is then followed by generating the VSPI frames using simulated Linear Array imageries. The space intersection is then applied to the VSPI frame using the DLT model. The simulated study indicates that the fitting accuracy of the DLT can be improved if a VSPI frame is generated using approximate elevation model in a pre-processing stage.

A novel higher order mode excitation method for a 8×8 cavity-backed slot Array antenna in Ku-Band is introduced in this letter. The antenna is formed by three main layers, consisting power divider, slotted cavities, and dipoles. All the 64 elements of the Array is simply excited by a coaxial probe located at the center of the ground plane. The power divider distributes the electromagnetic waves into the upper four cavities, which leads to the excitation of TE440 mode in each cavity. The fabricated antenna exhibits a maximum gain of 19. 6dBi and radiation efficiency of 80%. The measured S11<-10 dB is in the range of 14. 1-14. 3 GH. Moreover, the aperture efficiency of this antenna reached a peak of 72%.

The permanent magnet machine has attracted much attention due to its high torque density at low speed and simple configuration. This feature is due to many magnetic pole pairs that flux in the air gap can be significantly changed with the smallest motion of the moving. In this paper, a Linear dual stator flux reversal permanent magnet machine (LDSFRPMM) with toroidal winding is presented, which magnets embedded with Halbach and simple Array on the translator and stator, respectively. The innovation of this structure over a conventional machine is the addition of a magnet between the stator teeth with the appropriate magnetic orientation, and finding the best width of permanent magnet on the stator and a change of the type of winding from the concentrated to the toroidal. By implementing these changes on a conventional machine, the main parameters of the machine such as back electromotive force (EMF), thrust force, power factor and permanent magnetic (PM) flux are increased which improves the performance of the proposed machine.