Actual Physical Process Research Articles

Research and Analysis of Finite Difference Method and Least Square Method Identification Algorithm Based on CO2 Environmental Monitoring

According to the physical process of convection and diffusion followed by CO2 and the working principle of HVAC, a PDE model of indoor CO2 concentration is proposed according to the working conditions of indoor air flow in and out. The physical significance and selection principle of each component, initial and boundary conditions in the model are analyzed in detail. In order to prove the validity of the model, this paper, based on the different conditions of initial value and boundary value, puts forward the PDE model of indoor CO2 concentration The model is solved and simulated, and the results show that the dynamic evolution process of the model is consistent with the actual physical process; for the unknown parameters in the model, the finite difference method and the least square method are combined to realize the identification of the unknown parameters of the model, and the effectiveness of the identification method is verified by simulation.

Establishment and verification of diffraction BRDF model for scratched material surface

The surface reflectance at micro scale is mainly dominated by wave effect and cannot be explained by geometric ray model. In this paper, we use wave optics to analyze the incoherent reflectivity and gained important insights into the establishment of the diffraction BRDF model of scratched material surface. In order to confirm the model given, we improve the BRDF measurement method into the sub-aperture scanning Fourier transform system. The experimental data are in good agreement with the theoretical model. The proposed scratch diffraction BRDF model is more suitable to describe the actual physical process, and can provide theoretical basis for proposing detection scheme for scratches of different standards. The model can also be used to analyze the stray light of scratched material surface and the target characteristics of multi texture surface.

Reduced Model for Properties of Multiscale Porous Media with Changing Geometry

In this paper, we consider an important problem for modeling complex coupled phenomena in porous media at multiple scales. In particular, we consider flow and transport in the void space between the pores when the pore space is altered by new solid obstructions formed by microbial growth or reactive transport, and we are mostly interested in pore-coating and pore-filling type obstructions, observed in applications to biofilm in porous media and hydrate crystal formation, respectively. We consider the impact of these obstructions on the macroscopic properties of the porous medium, such as porosity, permeability and tortuosity, for which we build an experimental probability distribution with reduced models, which involves three steps: (1) generation of independent realizations of obstructions, followed by, (2) flow and transport simulations at pore-scale, and (3) upscaling. For the first step, we consider three approaches: (1A) direct numerical simulations (DNS) of the PDE model of the actual physical process called BN which forms the obstructions, and two non-DNS methods, which we call (1B) CLPS and (1C) LP. LP is a lattice Ising-type model, and CLPS is a constrained version of an Allen–Cahn model for phase separation with a localization term. Both LP and CLPS are model approximations of BN, and they seek local minima of some nonconvex energy functional, which provide plausible realizations of the obstructed geometry and are tuned heuristically to deliver either pore-coating or pore-filling obstructions. Our methods work with rock-void geometries obtained by imaging, but bypass the need for imaging in real-time, are fairly inexpensive, and can be tailored to other applications. The reduced models LP and CLPS are less computationally expensive than DNS, and can be tuned to the desired fidelity of the probability distributions of upscaled quantities.

Approximation of a class of functional differential equations with wideband noise perturbations

This work focuses on functional differential equations subject to wideband noise perturbations. Modeling using a white noise is often an idealization of the actual physical process, whereas a wideband noise can be easily realized in applications and well approximates a white noise. Using functional derivatives together with the combined perturbed test function methods and martingale techniques, this paper demonstrates that when a small parameter tends to zero, the underlying process converges to a limit that is the solution of a stochastic functional differential equation. To illustrate, an integro-differential system with wideband noise perturbation is examined as an example. Not only are the results interesting from a mathematical point of view, but also they are of utility to a wide range of applications.

A multiresolution wavelet optimised finite-difference method for simulation of thermal regenerator

The equations demonstrating the heat transfer phenomenon in a thermal regenerator were solved with the finite-difference method (FDM) and the method has been improvised by using wavelets. In the thermal regenerators, hot flue gas enters an initially cold bed, transfer all of its thermal energy in a portion of the bed and leaves at low temperature creating a heat transfer zone which traverses the bed-length with time while establishing the thermal equilibrium on both sides of the zone. The discretization process in conventional FDM takes uniform dense grids for whole domain, however, in actual physical process, the heat transfer happens only in a portion of the domain at a certain time requiring dense grids. Such problems demand a front-tracking method which can adjust the grid pattern according to the temperature-front location for which wavelets are found to be suitable. Wavelets functions have the property of being translated and dilated according to the requirement. An adaptive grid scheme has been developed using wavelets along with the multiresolution analysis. The grid patterns for different forms of Daubechies wavelets i.e. db1, db2, db3, and db4 have been compared. The method based on wavelets has been found accurate and less time-consuming.

Transient Signal Analysis Using Parallel Time-Frequency Manifold Filtering for Bearing Health Diagnosis

It is crucial to identify and extract the weak transient features embedded in the vibration signals for bearing health monitoring and fault diagnosis. However, due to the macro-structural disturbance and background noise interference, it is not easy to mine the transient features, especially at the apparent failure stage. Meanwhile, the actual mechanism of bearing fault detect can be not simply expressed by the formulated theory models without consideration of the actual physical collision process. To overcome these issues, motivated by the merits of time-frequency manifold (TFM), this paper proposes a new transient feature extraction method, called parallel time-frequency manifold (PTFM) filtering, by simultaneously using TFM-based reconstruction with TFM-based filter in parallel for transient feature extraction. First, to improve the computational efficiency of TFM, two-dimensional discrete wavelet transform is employed on the raw time-frequency distribution (TFD) with image compression. TFM learning is later used to mine the principle manifolds from those approximation sub-images. Then, the amplitudes of the raw time-frequency image can be reconstructed by TFM feature bases while the desired location of time-frequency feature can be captured by TFM morphology filter in a process of image morphology. With raw time-frequency phases in a series of inverse processes, the de-noised signal can be finally synthesized from these filtered images. The proposed method accomplishes a natural manifold feature denoising by combining the sparse theory with image morphology, and demonstrates attractive prospects in the following three aspects: signal de-noising with a self-learning mode in the view of image morphology processing combined with sparse theory, fault diagnosis with in-band noise/close interference removal, and machine health monitoring with capability in capturing sensitive failure information. Simulations and experiments confirmed the effectiveness of the proposed PTFM filtering method in noise suppression and feature enhancement, which is valuable for bearing health monitoring and diagnosis applications.

Study on Reciprocal Models for Magneto-Acousto-Electrical Tomography With Coil Detection

Magneto-Acousto-Electric Tomography with coil detection, known as Magneto-Acousto-Electric Tomography with Magnetic Induction (MAET-MI), is a non-contact resistivity-based imaging method that employs a coil to detect the induced current generated by the ultrasound in biological tissue, which lie under a static magnetic field. To reconstruct an image of the tissue's conductivity, we propose a reciprocal model to describe the relationship between the inducted voltage of a coil and its conductivity. Previous work on the reciprocal theorem demonstrates that reconstructing conductivity using this method is effective. The forward and inverse problem are usually not verified both numerically and experimentally. In this paper, different approaches are adopted to calculate the forward and the inverse problems for verification of the reciprocal model. This verifies that the reconstruction method based on electrode detection can be applied to MAET-MI. This means that the inverse problem of MAET-MI can be transformed into an inverse source reconstruction of a wave equation based on the coil detection. In the forward problem, the moment method is employed to calculate the Radon transform and generate the ultrasonic signals. For the inverse problem, the filtered back projection method is chosen to reconstruct the ultrasound sources, which are related to the curl of the current density in the reciprocal process. Based on the curl of the current density in the reciprocal process, four sets of correlation coefficients of the original and reconstructed images' model are all greater than 90%. The uniform error criterion is obtained via multiple reconstructions and comparison of multiple models. The reciprocal model exhibits a good uniformity and stability when describing the actual physical process. It also provides additional effective ideas for solving the inverse problem quickly to reconstruct the ultrasonic sources, which is corresponding to the actual distribution of the conductivity.

INVESTIGATION OF TEMPERATURE MODES IN THERMOSENSITIVE NON-UNIFORM ELEMENTS OF RADIOELECTRONIC DEVICES

Context. The non-linear boundary value problem of heat conduction for a thermosensitive non-homogeneous strip-shaped element of a radio-electronic system with a through inclusion has been solved whose analytical-numerical solution enables us to analyze temperature regimes in the element. Objective. Is to develop such a method of linearization of mathematical model of heat conduction which enables us to obtain analytical numerical solution of the corresponding non-linear boundary value problem for determination of temperature field in elements of radio electronic devices, which are geometrically represented by a thermosensitive plate with a through inclusion. Method. A linearizing function which enables us to partially linearize the initial non-linear mathematical model of heat conduction for a thermosensitive non-homogeneous element of a radio electronic system in the form of “plate-inclusion” structure has been suggested. The introduced piece-wise linear approximation of temperature on plate-inclusion interfaces has enabled us to completely linearize the corresponding partially linearized boundary value problem relative to the linearizing function. After this, it became possible to apply Fourier’s integral transformation to the obtained linear problem with respect to one of the spatial coordinates, as well as to determine the linearizing function. The linear dependence of the coefficient of heat conductivity on temperature for structure materials with the use of the linearizing function has been considered. By solving the boundary value problem, the formulae for determination of temperature field in the “plate-inclusion” thermosensetive structure have been obtained. Results. The obtained formulae for determination of temperature field in a thermosensitive non-homogeneous element of radio electronic system were used to create the software which enables us to obtain distribution of value of temperature and to analyze temperature regimes. Conclusions. A mathematical model for the calculation for the temperature field in a “plate-inclusion” thermosensitive structure is adequate to the actual physical process, because no jump of temperature at “plate-inclusion” interfaces is observed. The numerical results for the chosen materials under linear dependence of the coefficient of thermoconductivity on temperature differ by 7% from the results which are obtained for constant coefficient of heat conductivity. Prospect of further investigation will consider more complicated geometric representation of elements of radio electronic systems.

Electrical Characteristics of Microsecond Electrical Explosion of Cu Wires in Air Under Various Parameters

Electrical explosion of wires has caused the attention of researchers because of its rich physical phenomena and plenty applications. Microsecond electrical explosion of Cu wires in air under various parameters is conducted, and diverse discharge waveforms are displayed and analyzed. By statistically summarizing the experimental results, experimental parameter selection suggestions for specific applications are given. In addition, the experimental results show that the average axial breakdown field strength is greatly changed with the breakdown time. It drops linearly from ~13 to ~3 kV/cm when breakdown time varies from 2 to $6~\mu \text{s}$ , it keeps at a relatively low value about 1 kV/cm when the breakdown occurred after $8~\mu \text{s}$ . The effect of current density on the rising edge of the resistivity curve is confirmed by the experimental results. Based on the correlation between the breakdown time and breakdown field strength and the correlation between the maximum current density and specific action when resistivity reaches 200 $\mu \Omega \cdot \text {cm}$ , the specific-action model is improved empirically. The proposed “two-stage” model better reflects the actual physical process and has higher accuracy and a wider scope of application.

RETRACTED ARTICLE: Application of Monte Carlo calculation method based on special graph in medical imaging

With the rapid development of medical imaging technology and information technology, digital medical image acquisition equipment is constantly updated, especially the rise of proton medical technology, which has higher requirements on human diseased cell imaging technology. In this paper, based on the image data acquired by the large aperture CT, the Monte Carlo calculation and analysis of edge-blurred electronic density images have carried out to achieve accurate diagnosis and provide a new method for efficient pathological treatment. This article made a preliminary study and analysis on the application of Monte Carlo method in radio surgical treatment planning. Monte Carlo method, which is known as random sampling or statistical test methods, can truly simulate the actual physical process, problem solving and actual in good compliance. It can be very successful results. Combined with the image processing method, this paper carries out the detection methods of image pre-processing, image segmentation, feature extraction, classification and recognition to the lesion area of human body to realize the effective recognition of the special lesion image area. Experimental results show that the edge of lesion area has obtained by image segmentation, contour extraction and Monte-Carlo calculation. Particle-space information has taken as input. Based on Monte Carlo method, the space-absorbed dose in phantom is analysed distributed. By using the computerized liver cancer diagnosis technology, the doctor’s working pressure and labour intensity are reduced, the doctor’s working efficiency is improved, the accuracy of the diagnosis is improved, the hospital saves many expenses and the patient’s burden is reduced. Therefore, the research of computer-aided diagnosis has important significance and application value.

Exploring Electrical Currents through Nanographenes: Visualization and Tuning of the through‐Bond Transmission Paths

In this work, electrical currents through nanographenes, a class of alternant hydrocarbons also known as polycyclic aromatic hydrocarbons, in molecular junctions under small bias are explored. We illustrate that when the π-current dominates, that is, when no quantum interference takes place, the current prefers the direction of the shortest bond (the bond with the highest double bond character) upon entering the molecule from the contacts. As such, the idea of electrons propagating through double bonds from contact to contact, originating from the curly arrow drawings used in a previously established selection rule for transmission, seems to be more deeply rooted in the actual physical process of electron transport than previously anticipated. Furthermore, this work confirms that the σ-current behaves completely differently than the π-current. When this type of current becomes important, that is, when quantum interference takes place, the current generally prefers the shortest path from contact to contact, irrespective of the length of the bonds constituting this path, in accordance with the strong distance dependency of the σ-current. Finally, it is demonstrated that keto groups (and cross-conjugating groups in general) can be used to seal off parts of the molecule for the current. No current flows through the sealed off part of the molecule under small bias and it does not influence the transmission spectrum of the considered system.

General equations of lumped parameter ladder circuits and a special approach to analyzing electrical line transient states

The presented analytical procedure gives the equations that can be named as the General Equations of Lumped Parameter Ladder Circuits. The procedure is based on representing an electrical line through its lumped parameter model, applying the principle of superposition, and summation of the finite and infinite geometric series. The developed analytical procedure results in relatively simple analytical expressions for the relationship between currents and voltages at different points of transmission line models in both transient and steady state conditions. Also, the developed analytical procedure follows one by one all the phases of the actual physical process occurring during transient states in transmission lines. As such, this procedure is convenient for determination of power frequency over-voltages during a transient state of a transmission or distribution line. As an illustration of this, the paper presents a numerical example of determination of switching over-voltage at the open end of a transmission line.

Measurement Matrix Optimization for ISAR Sparse Imaging Based on Genetic Algorithm

Inverse synthetic aperture radar sparse imaging based on compressive sensing has been widely researched. The measurement matrix significantly affects the performance of target imaging. In this letter, focus on the kind of signals that consist of several subpulses with stepped frequency, a measurement matrix optimization method based on genetic algorithm (GA), is proposed. The actual physical observation process is considered and the target characteristics are utilized to optimize the measurement matrix. Then, the expected imaging results can be obtained with minimum data using the optimized measurement matrix. Meanwhile, the orthogonal matching pursuit algorithm is improved for signal reconstruction, which can reduce the computation load significantly. The effectiveness of the proposed method is demonstrated by experiments.

Numerical simulation and analysis of the effect of rain and surface property on wind-turbine airfoil performance

The performance of wind turbines is significantly affected by the atmospheric condition of their operating environment. Because rain is a common phenomenon in many parts of the world, understanding its effect on the performance of wind turbines provides valuable information in determining the site for a new wind farm. We developed amultiphase computational fluid dynamics(CFD)modelto estimate the effect of rain by simulating the actual physical process of rain droplets forming a water layer over the blades by coupling the Lagrangian Discrete Phase Model (DPM) and the Eulerian Volume of Fluid (VOF) models. We applied our model to a wind-turbine blade airfoil and studied the effect of rain for different rainfall rates in addition to the effect of surface tension and surface property of the airfoil. We observed that, at low rainfall rates, the performance of the airfoil is highly sensitive to the rainfall rate. However, if the rainfall rate is high enough to immerse most of the airfoil surface under water,a furtherincrease in the rainfall rate does not have a substantial effect on the performance of the airfoil.

No Quantum Process Can Explain the Existence of the Preferred Basis: Decoherence Is Not Universal

Environment induced decoherence, and other quantum processes, have been proposed in the literature to explain the apparent spontaneous selection - out of the many mathematically eligible bases - of a privileged measurement basis that corresponds to what we actually observe. This paper describes such processes, and demonstrates that - contrary to common belief - no such process can actually lead to a preferred basis in general. The key observation is that environment induced decoherence implicitly assumes a prior independence of the observed system, the observer and the environment. However, such independence cannot be guaranteed, and we show that environment induced decoherence does not succeed in establishing a preferred measurement basis in general. We conclude that the existence of the preferred basis must be postulated in quantum mechanics, and that changing the basis for a measurement is, and must be, described as an actual physical process.

Propagation of Massless Spin-1 Particle between Two Media

In general explanation for propagation of electromagnetic wave at a plane between two media of different dielectric properties. The description of this phenomenon be based on the actual physical process of the well know interpretation of the classical rays with the polarization vectors. In this research, we investigate this situation by using the knowledge of the amplitude of emission and absorption of massless spin-1 particle (photon) excitation by the emitter and detector, respectively. By using time evolution process based on vacuum-to-vacuum transition amplitude in quantum (field) theory QED formalism. This process shows that the propagation of photon excitation by the external sources is given with an explanation of the amplitude of propagation between different spacetime points from an emitter to a detector, which exclude with the Feynman propagator. The purpose of this research is developing a formalism based on the actual physical process of photons propagate from an emitter to a detector. It shows the consistency to the actual physical process of interpretation of the polarization vectors in the classical rays.

Integrated scheduling of material flows and information services in industry 4.0 supply networks

In this contribution, an original service-oriented form of structure dynamics control (SDC) and a model for dynamic scheduling of services for Industry 4.0 supply networks is developed. Problem of design and dynamic scheduling of services in cyber-physical systems is stated and solved with the help of SDC approach. The proposed service-oriented description makes it possible simultaneously to (i) determine the volume of information services needed for physical supply processes, (ii) determine this volume in monetary form, and (iii) interconnect each service with information systems needed for its realization. The results provide a base for performing service scheduling according to actual physical process performance and their adaptation (re-configuration) as well as for monetary estimation of investments into information systems and return on investments. Copyright © 2015 IFAC

Engine control unit PID controller calibration by means of local model networks

In this work a new approach for a fully automated calibration of nonlinear PID controllers and feedforward maps is introduced. Controller design poses a particularly challenging task in the application to internal combustion engines due to the nonlinear controller structure, which is usually prescribed by the manufacturer of the engine control unit (ECU). A dynamic local model network is used to represent the actual physical process as its architecture can beneficially be adopted for scheduling of the nonlinear controller parameters. The presented calibration technique uses a genetic algorithm to calibrate the nonlinear PID controller and a static model inversion to determine the feedforward map. Closed-loop stability is taken into account by incorporating a Lyapunov function. Finally, an example demonstrates the effectiveness of the proposed method.

Integrated dynamic scheduling of material flows and distributed information services in collaborative cyber-physical supply networks

An original model for dynamic scheduling of information services and material flows in collaborative cyber-physical supply networks is stated and solved with the help of the structure dynamics control approach. The proposed service-oriented description makes it possible to coordinate the availability of information services and material process schedules simultaneously. It also becomes possible to determine the volume of information services needed for the physical supply processes. In addition, the impact of disruptions in information services on the schedule execution in the physical structure is analysed. The results provide a base for information service scheduling according to an actual physical process execution.

Definition and Expression of Thermal Neutron Effective Proliferation Coefficient in the Uniformity Dispersion Nuclear Reactor with Uniformity Dispersion Source Neutrons

This paper will introduce the definition and expression of thermal neutron effective proliferation coefficient eff k after modification in the uniformity dispersion nuclear reactor with uniformity dispersion source neutrons and when studying the nuclear reactor physical process, we can exactly explain the phenomenon in the actual physical process and prove it for use.