A Modular System for Gear Calculations: A Comprehensive Computational Approach

In molecular dynamics (MD) calculations, reduction in calculation time per MD loop is essential. A multiple time-step (MTS) integration algorithm, the RESPA (Tuckerman and Berne, J. Chem. Phys. 1992, 97, 1990-2001), enables reductions in calculation time by decreasing the frequency of time-consuming long-range interaction calculations. However, the RESPA MTS algorithm involves uncertainties in evaluating the atomic interaction-based pressure (i.e., atomic pressure) of systems with and without holonomic constraints. It is not clear which intermediate forces and constraint forces in the MTS integration procedure should be used to calculate the atomic pressure. In this article, we propose a series of equations to evaluate the atomic pressure in the RESPA MTS integration procedure on the basis of its equivalence to the Velocity-Verlet integration procedure with a single time step (STS). The equations guarantee time-reversibility even for the system with holonomic constrants. Furthermore, we generalize the equations to both (i) arbitrary number of inner time steps and (ii) arbitrary number of force components (RESPA levels). The atomic pressure calculated by our equations with the MTS integration shows excellent agreement with the reference value with the STS, whereas pressures calculated using the conventional ad hoc equations deviated from it. Our equations can be extended straightforwardly to the MTS integration algorithm for the isothermal NVT and isothermal-isobaric NPT ensembles. © 2017 Wiley Periodicals, Inc.

The article discusses the methodology and technology of installing a new facade system on the old facade of the building, improving the appearance of the building and protecting the old facade, including the prevention of many problems. This research employs an analytical descriptive approach by gathering information on the methodology and technology used in installing modular facade systems on existing buildings. Data is collected through literature review and case studies of successfully implemented building renovation projects. The analysis results indicate that the use of modular systems in building renovation provides numerous benefits, including improved construction efficiency, cost and time reduction, as well as enhanced durability and aesthetics of the building. Moreover, the use of modular systems enables more flexible design adjustments according to the existing architectural context. The utilization of modular systems in building renovation brings positive impacts in enhancing the building's appearance while safeguarding the original facade and preventing various construction issues. By providing more efficient and flexible solutions, modular systems unlock significant potential in sustainably and aesthetically renewing existing building structures.

In order to evaluate the performance of denoising algorithms applied to Monte Carlo calculated dose distributions, conventional evaluation methods (rms difference, 1% and 2% difference) can be used. However, it is illustrated that these evaluation methods sometimes underestimate the introduction of bias, since possible bias effects are averaged out over the complete dose distribution. In the present work, a new evaluation method is introduced based on a sliding window superimposed on a difference dose distribution (reference dose-noisy/denoised dose). To illustrate its importance, a new denoising technique (ANRT) is presented based upon a combination of the principles of bilateral filtering and Savitzky-Golay filters. This technique is very conservative in order to limit the introduction of bias in high dose gradient regions. ANRT is compared with IRON for three challenging cases, namely an electron and photon beam impinging on heterogeneous phantoms and two IMRT treatment plans of head-and-neck cancer patients to determine the clinical relevance of the obtained results. For the electron beam case, IRON outperforms ANRT concerning the smoothing capabilities, while no differences in systematic bias are observed. However, for the photon beam case, although ANRT and IRON perform equally well on the conventional evaluation tests (rms difference, 1% and 2% difference), IRON clearly introduces much more bias in the penumbral regions while ANRT seems to introduce no bias at all. When applied to the IMRT patient cases, both denoising methods perform equally well regarding smoothing and bias introduction. This is probably caused by the summation of a large set of different beam segments, decreasing dose gradients compared to a single beam. A reduction in calculation time without introducing large systematic bias can shorten a Monte Carlo treatment planning process considerably and is therefore very useful for the initial trial and error phase of the treatment planning process.

A new approach to coupled two-phase reactive transport simulation for long-term degradation of concrete

The article is devoted to solving the actual problem of analysis and synthesis of actuators based on ferromagnetic shape memory alloy. A combined method of calculating plane-parallel magnetic fields of actuators has been developed: in a linear environment the method of point magnetic moments is used, in a non-linear environment the method of finite elements is used. Application of vector magnetic points allows reducing the dimensionality of the field calculation problem. The number of unknowns, compared with the finite element method, decreases by about 18 times with a relative error in calculating the magnetic flux density of less than 2 %. On the basis of the method, an algorithm has been developed to solve the inverse problem of determining the magnetomotive force of the magnetizing coils of the actuator taking into account the dependence of the magnetic properties of ferromagnetic shape memory alloy on its deformation and the effect on the deformation of the material of the external load. Algorithm provides considerable reduction of calculation time with required accuracy of magnetic field parameters determination. This allows us to effectively solve the problems of synthesizing actuators, to analyze malfunctions and predict their condition in real time. The proposed combined method can be used for calculating the magnetic fields of other electrical devices.

Systemic risk monitoring model from the perspective of public information arrival

The conventional speaker change detection (SCD) method using Bayesian Information Criterion (BIC) has been widely used. However, its performance relies on the choice of penalty factor and suffers from mass calculation. The twostep SCD is less time consuming but generates more detection errors. The limitation of conventional method’s performance originates from the two adjacent data windows. We propose a strategy that inserts an interval between the two adjacent fixed-size data windows in each analysis window. The dissimilarity value between the data windows is regarded as the probability of a speaker identity change within the interval area. Then this analysis window is slid along the audio by a large step to locate the areas where speaker change points may appear. Afterwards we only focus on these areas and locate precisely where the change points are. Other areas where a speaker change point unlikely appears are abandoned. The proposed method is computationally efficient and more robust to noise and penalty factor compared with conventional method. Evaluated on the corpus of China Central Television (CCTV) news, the proposed method obtains 74.18% reduction in calculation time and 22.24% improvement in F1-measure compared with the conventional approach.

Linear surfaces are used in various spheres of human activity. One of the most common techniques of designing linear surfaces is based on the three directing curves. In some cases, one of these directing curves is not set, but rather replaced by some geometric condition imposed on the emerging surfaces, which can in form of a certain point correspondence established between the points of the rest two directing curves. The article reviews the example of designing such surfaces, which in an approximate form would restrict the zone that sets the permissible positions of links of the manipulator mechanism of certain given configuration in realization of permissible instantaneous states. The acquired linear surfaces underlie the algorithm for calculation of configurations, which do not intersect the restricted zone in case of a deadlock situation. The result of this research is the computer simulation of the motions of arm and torso mechanism of the Android robot using the obtained algorithm for calculation of configurations. The simulation of motion demonstrates that the use of linear surfaces in analysis of the relative position of the manipulator and restricted zones in the deadlock situations allows reducing the calculation time by 50-60 percent. Such reduction of calculation time is highly demanded in computer control of the arm and torso motions of the Android robot on a real time scale.

Using a Monte Carlo method, we investigate the effect of a turbid medium on image transmission by means of the modulation transfer function approach. We present results that refer to a medium that consists of a random distribution of water spherical particles in air. We analyze the effect of geometric conditions (medium width and position) and source characteristics (Lambertian, beam emission). We present results for small spheres (Rayleigh scattering) and spheres (1.0-microm diameter) that are not small in comparison with the wavelength lambda = 0.6328 microm. Numerical data show a large modulation transfer function dependence on the source emission aperture and a substantial independence of the medium width for a fixed value of the optical depth. In accordance with reciprocity principles, we test an inverse scheme of Monte Carlo calculation, the advantage of this scheme being a substantial reduction in calculation time.

This study presents a numerical verification of the physical validity of using a quadratic dependence of the laser beamradius in modeling stimulated Raman scattering (SRS) in self-focusing media, such as toluene. The influence of various powerlawdependencies of the gain coefficient on the beam radius (n = 1, n = 2, n = 3) is analyzed in terms of numerical stability andresult accuracy. Two numerical approaches are developed: the Adams method with adaptive step size and the Euler iterativemethod with fixed step size, both based on energy conservation laws and the Kerr effect. The simulations are performed usingparameters typical for toluene (initial beam radius of 113 μm, refractive index of 1.49, laser wavelength of 694.3 nm, and criticalpower of 25 kW). The results show that the quadratic model (n = 2) provides the optimal combination of stability and physicalcorrectness, accurately capturing the Stokes generation threshold (zf ≈ 0.083 m) and power stabilization. The linear model (n =1) underestimates the self-focusing effect, violating energy conservation, while the cubic model (n = 3) exhibits numericalinstability. This work has practical significance for optimizing laser systems in spectroscopy, optoelectronics, and biomedicine.Moreover, an important aspect of developing numerical programs was to improve computational efficiency. Implementing themodeling in the form of standalone programs allows for a significant reduction in calculation time compared to manual analysisor the use of general-purpose software packages. This enables the investigation of complex nonlinear effects under realisticconditions with high spatial resolution

Spatial light modulators can be used for having dynamic three dimensional images. Diffraction pattern of three dimensional objects can be used for driving those imaging devices. Diffraction patterns have to be calculated rapidly to form dynamic three dimensional images. Furthermore, pixelated structure of the spatial light modulators have to be taken into account in the diffraction pattern calculation to improve the quality of the reconstructed objects. The proposed method for calculating diffraction patterns not only takes into account the pixelated structure of the spatial light modulator to obtain more accurate results, but also provides fast calculation of the diffraction pattern. The proposed method employs a lookup table which is formed by 469 pre-computed vectors and the computation time of diffraction pattern can be decreased significantly compared to standard diffraction pattern calculation method. The proposed method can be run in parallel, hence further reduction in calculation time can be achieved and even the diffraction pattern of a three dimensional object which is formed by 3144 points can be calculated within 80msec when the algorithm is run in parallel on a graphics processing unit. © 2014 IEEE.

This paper presents an approach to calculate temperature in the electrical machines critical parts when operating in intermittent operations. Focus in this paper is particularly placed on the traction motors that should be run in duty cycles with thousands of operating points during several hours, e.g. in e-mobility and railway applications. Normally, application of numerical methods in duty-cycle calculations is limited due to the long computation time which, in turn, results in a lower accuracy in temperature estimation. Here, numerical models are simplified and used efficiently together with analytical models so that calculation time is reduced significantly. The numerical methods include computational fluid dynamics and finite element models. The reduction in calculation time is from hours to minutes. The developed numerical and analytical methods are verified by measurements on an open self-ventilated traction motor and a good agreement is achieved both in transient and at steady-state temperatures.

The exponential growth of the computational capacity has, amongst other things, enabled the design engineer to include non-deterministic properties in the numerical simulation and validation of new designs. In this context, the fuzzy concept has been introduced for the description of incomplete data, subjective knowledge and modelling uncertainties in a non-probabilistic manner. The use of the fuzzy concept in the finite element context has led to the development of the fuzzy finite element method for eigenfrequency and frequency response function analysis. For industrially sized models with a large number of uncertainties, the computation time of these methods can be considerable. A reduction in calculation time can be achieved by the substructuring of large models into superelements, which are then independently processed and reduced, and afterwards recombined. In the presented work, the fuzzy finite element method is combined with the Craig-Bampton component mode synthesis substructuring technique, in which the static and dynamic behaviour of each superelement are represented by a set of component modes. Special attention is paid to the consequences of uncertain parameters on the numerical representation of an uncertain superelement. A concept for the description of uncertain component modes is presented, and the influence of global as well as local uncertainties on the accuracy of the interval results of the reassembled model is studied. A numerical case study is presented to illustrate the concepts used in this paper.

On the rotors of an axial-flux PM machine, NdFeB permanent magnets (PM) are very often placed because of their high energy density. As the NdFeB-magnets are good electric conductive, electric currents are induced in the magnets when they are exposed to a varying magnetic field. This varying magnetic field has two causes: variation of the airgap reluctance due to the effect of stator slots and armature reaction due to the stator currents. As axial-flux PM machines have an inherent 3-D-geometry, full 3-D-finite-element modeling seems necessary to calculate the eddy currents in the PM and to evaluate their corresponding losses. In this paper, however, the 1-D airgap magnetic fields of multiple multilayer 2-D finite-element simulations are combined to a 2-D airgap magnetic field using static simulations. In a subsequent step, this 2-D airgap magnetic field is imposed to a 2-D finite-element model of the PM to calculate the eddy currents and eddy current losses. The main benefit of this multilayer 2-D-2-D coupled model compared to 3-D finite-element modeling is the reduction in calculation time. Accuracy of the suggested multilayer 2-D-2-D coupled model is verified by simulations using a 3-D finite-element model.

Simplified Models for High Pressure Die Casting Simulation