channel is characterized not only by its DOA but also time delay of the diﬀerent propagation paths. Van der Veen proposed a joint angle and delay estimation algorithm based on the smoothing method and joint diagonaliza- tion technique. A lower bound of number of receiving antennae and oversampling diversity for parameters iden- tiﬁcation has been presented for the given algorithm [1,8,9]. Recently, Sidiropoulos and Liu  linked trilinear decomposition to array signal processing and guaranteed several improved identiﬁability results of parameter esti- mation based on PARAFAC analysis, which introduces a new perspective to parameters estimation.
number of Monte Carlo simulations. There are 10 an- tennae in the receiving antennae array, and the number of snapshots N ¼ 100 . SNR varies from 10 to 30 dB. Five hundred independent Monte Carlo runs are simu- lated. Figures 4 and 5 present the RMSE curve of angle and delay estimations versus SNR. Four sub-figures of each figure, titled as (a), (b), (c), (d), depict perform- ance of four rays with parameters (15°, 1.5Tp), (25°, 2.5Tp), (45°, 4.5Tp), and (55°, 5.5Tp). The RMSE values of parameter estimation of PARALIND-JADE are less than that of E-JADE-ESPRIT. It implies that the pro- posed algorithm has better accuracy in parameter estimation.
Interference from other users can be either unintentional or intentional (Halim, 2001). Unintentional interference is caused by nonidealities in the transmitter or using the same or adjacent channel. Intentional interference or jamming is radiation directed towards a target for the purpose of trying to prevent it from receiving the desired signal. Potential interference in signal processing and telecommunication applications has been a main concern for system designers, and usual filtering techniques are not helpful as the interference signal and desired signal are of the same frequency. Many methods have been adopted to avoid interference, including frequency hopping, but it requires immoderate bandwidth. ABF can solve the problem without the need for additional bandwidth as signals are filtered on the basis of their direction of arrival (DOA). Smart antennas (SAs) possess the capability of suppressing interference signal, so they can improve the signal to interference plus noise ratio (SINR). Array processing utilizes information regarding locations of signal to aid in interference suppression and signal enhancement and is considered the promising technology for interference nulls (Das and Sharma, 2012).
where each individual mirror can be rapidly repositioned to ON or OFF corresponding to a ±12 degree tilt from the flat state. A 1920×1080 resolution array has over two million mirrors, each mirror corresponding to a pixel of an image. The illuminated surface of the micromirror array can be magnified to form the images of a movie at the theater, or demagnified onto the atom sample to create the images of a dynamical optical potential U 0 (z) and δU (z, t). The surface of the digital micromirror device (DMD) acts like an
Recently, in contrast to a conventional array configuration, the DOA estimation method using electronically steerable parasitic array radiator (ESPAR) which has only one RF port has been investigated because of inexpensive hardware structures. Although the system using a ESPAR has many advantages, the lack of samples for constructing correlation matrices and phase calibration errors between the array elements degrade the estimation accuracy [7–12].
ISSN(E): 2277-128X, ISSN(P): 2277-6451, DOI: 10.23956/ijarcsse/V7I8/0130, pp. 36-40 Here we are computing the weights and beam formed pattern of the linear smart antenna. Here we also calculate mean square error to check the performance of LINEAR smart ANTENNA. The simulation work is divided into three parts. The performance criteria are mean square error and weight error function. We are considering the three different cases.
An Algorithm for Determining Talker Location using a Linear Microphone Array and Optimal Hyperbolic Fit An Algorithm for Determining Talker Location using a Linear Microphone Array and Optimal Hyperbo[.]
In , Tallafha gave an example of a space which was the semi-linearuniform space, but not metrizable. Till now, to define a function f that satisfies Lipschitz condition, or to be a contraction, it should be defined on a metric space to another metric space. The main idea of this paper is to define such concepts without metric spaces, and we just need a semi-linearuniform space, which is weaker as we mentioned before.
a single ridged rectangular waveguide is proposed. This paper presents slot array with similar inclination for all slots, slot array with different inclination and non- uniform length slots with different inclination on broad wall of a single ridged rectangular waveguide for vertical polarization. The co and cross polarization curves of the three designs are compared at different angles of observation.
Genetic Algorithms are a family of computational methods inspired by evolution [Holland, 1975; Goldberg, 1986; Goldberg & Holland, 1998]. A genetic algorithm (GA) is a procedure used to find approximate solutions to search problems through techniques such as genetic inheritance, natural selection, mutation, and reproduction (recombination, or crossover). Genetic Algorithms are typically employ using computer simulations in which various problem of optimization is specified. In this problem, array is called individuals and one element of element is called chromosome. The GA consists of an iterative process that evolves a working set of individuals called a population toward an objective function, or fitness function. Traditionally, solutions are represented using fixed length strings, especially binary strings, but alternative encodings have been developed.
Meanwhile, Reigber  proposed a 3D range migration algorithm (RMA) for SAR tomography imaging. Lopez- Sanchez and Fortuny  and Fortuny  developed a 3D RMA for 2D planar scanning aperture in the near-field zone of the target. Tan et al.  proposed a 3D RMA for SAR tomography imaging with digital spotlight in the elevation direction. All of these 3D RMAs are suitable for the monostatic configuration, where the signal spectrum in 3D wavenumber domain only contains constant and linear phase terms. However, due to the dual square root in the bistatic configuration, the signal spectrum in 3D wavenumber domain contains nonlinear phase terms besides constant and linear phase terms. Therefore, the 3D RMAs [17–20] mentioned above cannot be applied to the bistatic configuration directly.
Fast recursive algorithms for calculating the radiation patterns of fractal arrays have recently been developed in [6–8]. These algorithms are based on the fact that fractal arrays can be formed recursively through the repetitive application of a generating array. A generating array is a small array at level one (P = 1) used to recursively construct larger arrays at higher levels (i.e., P > 1). In many cases, the generating subarray has elements that are turned on and oﬀ in a certain pattern. A set formula for copying, scaling, and translating of the generating array is then followed in order to produce a family of higher order arrays.
Abstract. Parametric acoustic receivingarray can achieve higher space gain with relatively small (virtual) array aperture compare with ordinary line array. The amplitude of the secondary signals of parametric receivingarray is proportional to the third power of the acoustic velocity of the medium, and two-phase media is much more practical than single medium with slow acoustic velocity in underwater acoustic engineering. Two-phase media model and equations for the secondary signals of parametric acoustic array are proposed and some calculation examples are given and analyzed.
Lineararray has excellent directivity and it could give the narrowest major-lobe in a given direction. But it does not work well in all azimuth directions. Circular array is suited to provide 360 of coverage in azimuth plane. Directional patterns obtained with a circular array can be electronically rotated within the plane of the array without a considerable change of the beam shape. This is because circular array does not have edge elements. Circular array has high side lobes. Moreover compared to linear and rectangular arrays circular arrays are less sensitive to mutual coupling between their elements.
after it was complete. These other methods include off-line acoustic imaging, peel tests, and cross-sections which helped confirm nugget diameters and detect voids within the spot welds. The linear phased array system is able to detect voids within spot weld but is limited to only detecting voids along the path the linear phased array can image. Although the B-scans acquired of the welding process were able to produce a nice video of the welding process, it was difficult to determine an actual nugget diameter from these images. Instead, the M-scans were analyzed to measure nugget diameters. The algorithm for measuring nugget diameter presented provided fairly accurate measurements for welds which did not contain too much noise. The thresholds used in the algorithm could be optimized for specific applications. Finally, it appears likely that the linear phased array system could be successfully extended to a two-dimensional matrix system that could in theory, image the entire region of a spot weld in real-time.
Abstract—In this paper, the direction of arrival (DOA) and polarization parameters are estimated by a uniform circular array (UCA) with several single-polarized sensors. An eﬃcient and improved polarization MUSIC algorithm for estimating the DOA and polarization parameters is presented. This method uses information on the amplitude to reduce the computational complexity. When the source is linearly polarized, the proposed algorithm is more accurate at a low signal-to-noise ratio (SNR). Monte Carlo simulations verify the eﬃcacy of the proposed method.
To optimize the non-uniform antenna array to produce an acceptable pattern to the desired one with as few elements as possible, the proposed combined optimal strategy and matrix pencil method are used. In this case study, the objective function as defined in (9) is used, with other things being equal to case study one. For the desired radiation pattern produced by a 30 uniformly spaced antenna array optimized by using a modified tabu search algorithm , the number of elements of the non-uniform arrays searched by using the matrix pencil method and proposed combined strategy is 19 . Figure 6 shows the field patterns of the optimized non-uniform antenna arrays as well as the result given by . Table 7 presents the final optimal results of these 19 element arrays. The values of the objective function for the reconstructed non-uniform antenna arrays of the proposed strategy and the MPM are, respectively, 6.10743 × 10 −2 and 4.27919 × 10 −1
Among the first investigations on this topic, the most important one is the study of Reddy, 2007 , in which the analytical solutions of bending, buckling and vibration for nonlocal differential elasticity approach of various beam theories are developed. Wang et al., 2007  investigated the bending vibration problem of micro- and nanobeams based on the Eringen’s nonlocal elasticity theory and Timoshenko beam assumptions. By using the nonlocal continuum rod model, axial vibration of nanorod with various end conditions was investigated by Aydogdu, 2009 . The free vibration and bending of cantilever microtubules with nonlocal continuum model and fixed- free boundary condition were surveyed by Civalek et al., 2010 . Phadikar and Pradhan, 2010  introduced a finite element solution for nanobeams and nanoplates using the nonlocal differential constitutive relations of Eringen. Based on nonlocal Timoshenko beam theory, stability analysis of nanotubes embedded in an elastic matrix was also performed by Wang et al., 2012 . Akgoz and Civalek, 2013  calculated linear buckling response of linearly tapered micro-columns having different taper ratios via Rayleigh-Ritz method. The surface effects on the nonlinear free vibration of elastically restrained non-local beams with variable cross-section were examined by Malekzadeh and Shojaee, 2013 . Ritz method was utilized by Ghannadpour et al., 2013  to investigate the bending, buckling and vibration of nonlocal Euler beam with arbitrary boundary conditions. Tsiatas, 2014  presented a new influential approach to exactly determine stiffness and mass matrices of non- uniform Euler-Bernoulli beam from inhomogeneous linearly elastic material resting on an elastic foundation. An investigation on transverse vibration characteristics of rotating functionally graded Timoshenko size-dependent nanobeams made of porous as well as functionally graded material via the semi-analytical differential transformation
7. Conclusions. This paper has dealt with the global uniform exponential stability independent of delay (g.u.e.s.i.d.) of a class of homogeneous time-delay systems being possibly subject to combined point and distributed delays as well as integrodiﬀerential Volterra-type delayed dynamics. The global stability is investigated for any real func- tion of initial conditions being everywhere continuous on its deﬁnition domain, a real interval [ − h,0], where h is the maximum delay in the system, except possibly on a set of zero measure where the function of initial conditions possesses bounded discontinu- ities. Necessary and suﬃcient global uniform stability independent of delay conditions has been obtained if the delay-free system is globally uniformly exponentially stable (g.u.e.s.) and an auxiliary system is g.u.e.s.i.d. The obtained results have then been ap- plied to a number of particular cases of interest by setting diﬀerent auxiliary systems including the standard delay-free one. Furthermore, some extensions have been given for the case when the system is forced by impulsive inputs consisting of either a ﬁnite number of impulses or inﬁnitely many impulses. It has been assumed either that the impulse amplitudes vanish exponentially or that the time interval between two inputs exceeds a prescribed threshold of suﬃciently large length. Some extensions have been given by considering the closed-loop stabilization of time-delay systems of the given class. Finally, some illustrative examples have also been presented.
2-D direction-of-arrival (DOA) estimation of incident coherent source signals has received increasing atten- tion in radar, sonar, and seismic exploration [1–5]. Many high-resolution techniques, such as MUSIC  and ESPRIT , have achieved exciting estimation per- formance. However, the aforementioned methods assume the incident signals are independent, which would encounter performance degradation due to the rank deficiency when coherent signals exist. To decorr- elate coherent signals, the spatial smoothing (SS)  or forward-backward spatial smoothing (FBSS)  are especially noteworthy. However, this technique gener- ally reduces the effective array aperture, and the maximum number of resolvable signals cannot exceed the number of array sensors. In , an effective matrix decomposition method utilizing cross-correlation matrix is proposed to decorrelate coherent signals. Chen et al.  have proposed a 2-D ESPRIT-like method that