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Under the condition of extremely under-sampling, the iterative algorithm based on the total variation(TV) constrain is common for the reconstruction of optical deflection tomography. In the algorithm, the minimization of TV is implemented by the gradient descent approach, and the constraints are performed by projection on convex sets (POCS). In this paper, we discuss the modulation factor of the gradient descent method, and propose a new adaptive modulation factor for gradient descent. Experiments were done on a series of modulation factor functions under different projection angles and noise environment, and the experimental results were compared and analysed. And the algorithm proposed in this paper is compared with the soft threshold filter TV minimization algorithm. The results demonstrate that the adaptive modulation factor proposed in this paper can automatically and continuously update the value of the modulation factor, reduce the reconstruction error and improve the reconstruction quality. [ABSTRACT FROM AUTHOR]

The robustness of truncated Airy beam in parity-time (PT) symmetric Gaussian potentials media is numerically investigated. A high-peak power beam sheds from the Airy beam due to the media modulation while the Airy wavefront still retain its self-bending and non-diffraction characteristics under the influence of modulation parameters. Increasing the modulation factor results in the smaller value of maximum power of the center beam, and the opposite trend occurs with the increment of the modulation depth. However, the parabolic trajectory of the Airy wavefront does not be influenced. By utilizing the unique features, the Airy beam can be used as a long distance transmission source under the PT symmetric Gaussian potentials medium. [ABSTRACT FROM AUTHOR]

This paper presents a novel torque control method for two-level-inverter-fed induction motor drives. The control principle is based on a finite-control set model predictive control (FCS-MPC) using a state tracking cost index. In the online procedure of the proposed FCS-MPC, the optimal voltage vector and its corresponding optimal modulation factor are determined based on the principle of torque and rotor flux error minimization. In this method, a reference state is determined in a systematic way so that the reference torque tracking with maximum torque per ampere and flux-limited operation could be achieved. In addition, a weighting matrix for the state tracking error is optimized in offline using the linear matrix inequality based optimization problem. The efficacy of the proposed FCS-MPC method is proved by the simulation and experimental results at different working circumstances. The comparison of the presented control system with the conventional FCS-MPC and with other reported FCS-MPC with modulation control is made. The proposed algorithm yields fast dynamic performance and minimum torque and current ripples at different speed and torque levels. [ABSTRACT FROM PUBLISHER]

Nonlinear acoustic coefficients have a close relationship with structural cracks. A nonlinear ultrasonic modulation method for micro-crack quantitative evaluation is developed. The influence of phase threshold on the crack evaluation is discussed. Ultrasonic modulation using a unilateral incentive model is applied to the quantitative evaluation of micro-cracks for different specimens. The experimental results indicate that the method can be beneficially applied for micro-cracks detection. A proper phase threshold can improve the reliability of the method based on nonlinear ultrasonic modulation. The presented modulation factor can be used to quantitatively evaluate the structural cracks, and it is suitable for small-crack quantitative evaluation. [ABSTRACT FROM AUTHOR]

Purpose: The overall aim was to conduct an analytical study of the impact of the modulation factor (MF) on the quality of the head and neck treatment plans and their execution time on Tomotherapy. Materials and Methods: In-phantom (RANDO® Alderson) planning study of the head and neck cancer was performed. Thirteen different plans in terms of MF were prepared. Other optimization parameters were the same for all plans. Results: Analysis of treatment plans in terms of quality shows that MF < 1.4 does not provide an accepted dose distribution (physician decision). Statistically significant differences were observed for plans with an MF < 1.6. No differences were obtained for plans with MF from 6.0 to 1.8. Decreasing of MF leads to a shorter time of irradiation. The maximum rotational speed has been reached for an MF = 3.0. Further reducing this however produces no decrease in the time of irradiation. The actual and planned values of the MF were compared. The optimal range of MF for head and neck was determined as 3.0 > MF > 1.8. The lower limit increases to 2.4 when hard reduction of the dose in critical organs is required. Conclusions: It was showed that the final MF value is less than the value calculated after each loop of optimization. The computer system reduces MF by shortening the longest time and increasing the average time of leaves opening. Increase in the average time is obtained by eliminating the use of leafs with the shortest times of opening, thereby reducing the dose in critical organs that are outside the direct irradiation area. [ABSTRACT FROM AUTHOR]

Cumulants are usually interpreted as the connected components of density matrices, but this interpretation fails and practical problems arise when the rank n of cumulants is larger than the number of particles ( N) in the system. In that case, cumulants defined in the traditional way become disconnected. To solve this problem, the definition of cumulants is extended by introducing a simple modulation factor. The modified cumulants reduce to the conventional definition, but they vanish when N < n. Using the modified definition also eliminates the error in the approximation of density matrices by low-rank cumulants, when N < n. The problem assumes a slightly different form when we work with active space-based theories, and it can be solved by a similar approach. Another problem with cumulants, due to spin coupling [Herbert, Int J Quantum Chem 2007, 107, 703], can be solved via the introduction of a similar modulation factor. A related yet more serious issue, termed as the local particle number constraint problem, is also discussed. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 [ABSTRACT FROM AUTHOR]

Rett syndrome is a neurodevelopmental disorder mainly caused by de novo mutations in the MECP2 (methyl-CpG-binding protein 2) gene. There is considerable variation in the severity of clinical features among Rett syndrome patients, even among patients with the same MECP2 mutation. In addition to X-chromosome inactivation pattern, the genetic background of the affected individual might also have a role in determining the severity of the disorder. We suggest that APOE is one of the genetic modulating factors. We analyzed clinical phenotypes of 46 patients with Rett syndrome, with confirmed MECP2 mutation. We discovered that among ϵ4 carriers, some clinical features were more severe, and the developmental regression occurred 4 months earlier on average than in those without the ϵ4 allele. Earlier onset of regression suggests a possible trend; however, it did not achieve distinctive statistical significance. Nevertheless, the ϵ4 allele of APOE may serve as a candidate modulation factor for the Rett syndrome phenotype. [ABSTRACT FROM AUTHOR]

One-pot systems are an interesting proposal to carry out multi-enzymatic reactions, though this strategy implies establishing an optimal balance between the activity and operability of the involved enzymes. This is crucial for enzymes with marked differences in their operational stability, such as one-pot production of lactofructose syrup from cheese whey permeate, which involves two enzymes—β-galactosidase (β-gal) and glucose isomerase (GI). The aim of this work was to study the behavior of one-pot sequential batch production of lactofructose syrup considering both enzymes immobilized individually, in order to evaluate and design a strategy of replacement of the catalysts according to their stabilities. To this end, the modelling and simulation of the process was carried out, considering simultaneously the kinetics of both reactions and the kinetics of inactivation of both enzymes. For the latter, it was also considered the modulating effect that sugars present in the medium may have on the stability of β-gal, which is the less stable enzyme. At the simulated reaction conditions of 40 °C, pH 7, and 0.46 (IUGI/IUβ-gal), the results showed that considering the stability of β-gal under non-reactive conditions, meaning in absence of the effect of modulation, it is necessary to carry out four replacements of β-gal for each cycle of use of GI. On the other hand, when considering the modulation caused by the sugars on the β-gal stability, the productivity increases up to 23% in the case of the highest modulation factor studied (η = 0.8). This work shows the feasibility of conducting a one-pot operation with immobilized enzymes of quite different operational stability, and that a proper strategy of biocatalyst replacement increases the productivity of the process. [ABSTRACT FROM AUTHOR]