Background: Vibro-acoustography is an elasticity imaging method that images the acoustic response of a material to a localized harmonic excitation generated by ultrasound radiation force [Fatemi and Greenleaf, Science 280:82-85, 1998]. Proper beam forming for the stress field (radiation force) of the probing ultrasound is very important because it determines the resolution of the imaging system...

Flexible forming processes are characterized by the implementation of shape-independent tools. However, varying properties of semi-finished goods in conjunction with the lack of a forming tool technology also lead to an insufficient reproducibility of the products. In order to overcome this problem a closed-loop control system for the on-line-capable process control was worked out for laser for...

The trend in the conception of future spaceborne radar remote sensing is clearly toward the use of digital beamforming techniques. These systems will comprise multiple digital channels, where the analog-to-digital converter is moved closer to the antenna. This dispenses the need for analog beam steering and by this the used of transmit/receive modules for phase and amplitude control. Digital be...

This paper presents a tested research concept that implements a complex evolutionary algorithm, genetic algorithm (GA), in a multi-microcontroller environment. Parallel Distributed Genetic Algorithm (PDGA) is employed in adaptive beam forming technique to reduce power usage of adaptive antenna at WCDMA base station. Adaptive antenna has dynamic beam that requires more advanced beam forming algo...

There is clear difference in each fiber-optic link’s power output, in the large scale optically controlled phased array antenna. In order to realize the optical power balance and control between the various channels, the equilibrium or control power of each optical signal needs to be considered, and it will reduce the optical beam forming network generated side-lobe beam, which results in the p...

The current wireless cellular base station antenna system employs switched beam technology which suffers from its inefficiency to track the user and limited capacity. The Smart antenna technology which tracks the mobile user continuously by steering the main beam towards the user and at the same time forming nulls in the directions of the interfering signal. The development of smart antennas in...

This paper describes a method and a control system of a scanning electron and a bremsstrahlung pulsed beam for industrial linac. The system uses ultrasonic emission generated by the beam in thin rods and plates, as a source of primary information about the current characteristics of each electron/bremsstrahlung pulse. The results of the uniform radiation field forming are discussed.

Adaptive smart antenna arrays are used for cellular communication. This paper presents a comparative study of beamforming techniques for adaptive smart antenna using hybrid algorithms like Simple Matrix Inversion with Recursive Least Square (SMI-RLS) and Least Mean Square with Recursive Least Square (LMS-RLS) algorithm. The results are compared on the basis of null depth and error plot for diff...

One of the exciting prospects for large N arrays is the potential for custom beam forming when operating in phased array mode. Pattern nulls may be generated by properly weighting the signals from all antennas with only minor degradation of gain in the main beam. Here we explore the limits of beam shape manipulation using the parameters of the Allen Telescope Array. To generate antenna weights,...

The use of multi-user multiple-input multiple-output (MU-MIMO) transmission is an attractive strategy to increase spectral efficiency in wireless systems such as 3GPP Long-Term Evolution (LTE) and LTE-Advanced. In this work, we investigate beamforming and scheduling strategies in the downlink of limited feedback MU-MIMO systems. Modeling transmission under orthogonal frequency-division multiple...