Transmission characteristics of layers that contain fractal aggregates are investigated. In particular, the modulation transfer functions of these layers are studied in comparison with the case of uniformly dispersed particles. The effects of aggregation type (fractal dimension) and aggregate size are discussed.

Introduction The change in shape of a wavefront passing through or being reflected from an optical system, compared to the incident wavefront is an indication of the quality of the optical components. A quality indicator is the Modulation Transfer Function (MTF) of the image. There are two common methods of measuring MTF in optical components in systems: Fourier transform of measured linespread...

This study aims to investigate the potential use of LaBr3:Ce and LaCl3:Ce materials in SPECT imaging. GATE Monte Carlo simulations of single-head gamma camera and a Tc point source were performed to evaluate the energy spectra, modulation transfer function (MTF) and detection efficiency. A range of Ce concentrations (0.5, 5, 10 and 15)% of LaBr3:Ce and LaCl3:Ce crystals was simulated in conjunc...

This paper proposes a general method to design the noise-transfer-function of a continuous-time Σ∆ modulator having high-order passive LC loop filters. The feedback signals can have arbitrary shapes and can be applied either at internal nodes or only at the input node. As a design example, this technique is used to design a 4 order Σ∆ modulator where the internal nodes of the loop filter are re...

An extension of the traditional modulation transfer function (MTF), the detective MTF, is proposed for the evaluation of the resolution of X-ray imaging detectors with non-uniform efficiency on the scale of individual detector elements. The dMTF is shown to give a better representation than does the MTF of the improved resolution reported when the readout of the detectors is enhanced.

This paper represents a method to improve the SNR and linearity of an integrator by feedback compensation technique. The discussed design reduces signal swing while keeping advantages of both feed-forward as well as feedback topology without changing the signal transfer function. SNR and linearity are related to the output of an integrator. Reduced SNR and non-linearity resulted because of the ...

This paper proposes a framework for spectral enhancement of reverberant speech based on inversion of the modulation transfer function. All-pole modeling of modulation spectra of clean and degraded speech are utilized to derive the linear prediction inverse modulation transfer function (LP-IMTF) solution as a low-order IIR filter in the modulation envelope domain. By considering spectral estimat...

This paper discusses important elements of the Pockels sensing cell design. A novel electrode geometry is analyzed in order to obtain maximum sensitivity response from Pockels crystals (Bi(12)GeO(20)). This neither transversal nor truly longitudinal geometry, results in electrical field distribution along the sensing beam path that provides high modulation depth. Demonstrated performance level ...

Voltage-oriented PI control of three-phase gridconnected pulsewidth-modulation rectifiers with LCL filters is addressed. LCL filters require resonance damping. Active resonance damping is state of the art to face the problem, but it is still under investigation because of the manifold solutions. It is often realized using many sensors and/or complex control algorithms. In contrast, pure PI cont...

The design of a quadrature bandpass Sigma-Delta (Σ∆) ADC build by cascading two complex modulator is presented. The utilization of cascading enables the independent control of zeros of the noise transfer function. Design method and simulation results including errors due to non-idealities as well as limits of a fourth order scheme are presented. The flexibility of placing notches at critical fr...