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A numerical study and simulation of breast imaging in the early detection of tumors using the photoacoustic (PA) phenomenon are presented. There have been various reports on the simulation of the PA phenomenon in the breast, which are not in the real dimensions of the tissue. Furthermore, the different layers of the breast have not been considered. Therefore, it has not been possible to rely on the values and characteristics of the resulting data and to compare it with the actual state. Here, the real dimensions of the breast at threedimensional and different constituent layers have been considered. After reviewing simulation methods and software for different stages of the PA phenomenon, a single suitable platform, which is commercially available finite element software (COMSOL), has been selected for simulating. The optical, thermal, elastic, and acoustic characteristics of different layers of breast and tumor at radiated laser wavelength (800 nm) were accurately calculated or obtained from a reliable source. Finally, by defining an array of 32 ultrasonic sensors on the breast cup at the defined arcs of the 2D slices, the PA waves can be collected and transmitted to MATLAB software to reconstruct the images. We can study the resulting PA wave and its changes in more detail using our scenarios. [ABSTRACT FROM AUTHOR]

Developing an analog-to-digital converter (ADC) based on the time-interleaved delta–sigma modulator (TIDSM) is an appropriate technique to attain high-speed ADCs. TIDSMs can be successfully accomplished with the aid of developing the block digital filtering (BDF) method. In this approach, M mutually cross-connection delta–sigma modulators are used, whereby each one of them operates at a sampling rate of f s , leading to an effective sampling rate of M ∗ f s . In this study, a novel structure is proposed based on the Noise Coupled time-interleaved delta–sigma modulator (NC-TIDSM) with reduced hardware complexity. This structure not only increases the overall noise transfer function (NTF) order, but also reduces the hardware element counts. The simulation results demonstrate that the SNDRs of the first-order two-channel and four-channel NC-TIDSM with reduced hardware are 13 and 15 dB better than those of their BDF technique counterparts; also, the SNDR of the second-order two-channel NC-TIDSM with reduced hardware is 8 dB better than that of their BDF technique counterpart; also, the hardware element quantities are reduced dramatically. Moreover, some practical challenges such as the finite op-amp's gain and mismatching effects that directly affect the circuit implementation of the proposed structure have been described. Furthermore, the hardware complexity of the proposed structures is reduced considerably in comparison to that of the BDF technique with the NC-TIDSM structure. [ABSTRACT FROM AUTHOR]

The exact measurement of multiphase flow is an important and essential task in the oil and petrochemical related industries. Several methods have already been proposed in this field. In the existing methods, flow rate measurement depends on the fluid flow pattern. Flow pattern recognition requiring calibration has created instability in such systems. In this paper, a imple and reliable method is proposed which is based on ultrasonic tomography. It is free from calibration and instability problems that existing methods have. The obtained data from a 32-digit array of ultrasonic sensors have been used and the two-phase flow rate including liquid and gas phases have been calculated through a simple algebraic algorithm. Simulation results show that while applying this method the measurement technique is independent from the fluid flow pattern and the system error is decreased. For the proposed algorithm, the average amount of the spatial imaging error (SIE) for a bubble at different positions inside the pipe is about 5%. [ABSTRACT FROM AUTHOR]

In this paper, a low-power second-order feed-forward capacitor-structure continuous-time Δ Σ modulator with a 4-bit asynchronous successive approximation register (SAR) quantizer is presented. Through the utilization capacitor structure in the proposed modulator, first, the summation node of the integrators' outputs and the feed-forward signals is implemented within the second integrator to reduce power consumption by eliminating an active summing amplifier. Second, the proposed architecture can compensate for the quantizer delay without using any excess inner digital to analog converter (DAC). In this design, the modulator applies two different low-power operational amplifiers. These advantages cause the modulator to consume very low power and achieve a favorable figure of merit (FOM) value. In fact, in this paper, the combination of the previously reported methods and designs and doing required reforms has led to a new design with better performance, especially in power reduction. The designed modulator which is simulated using 0.18 μ m CMOS technology achieves 95.98 dB peak signal-to-noise and distortion (SNDR) for 10 KHz signal bandwidth and dissipates 44 μ w while its FOM is obtained about 43 fJ/conv.-step. [ABSTRACT FROM AUTHOR]