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This study explains the conductive mechanism of C12A7:C from the perspective of crystal structure. C12A7:C is a carbon derivative of C12A7 and prepared by CaCO3 and Al2O3 in sealed graphite crucible through high-temperature sintering experiments. The main component was confirmed to be C12A7:C through X-ray diffraction inversion analysis. The four-probe method revealed that it is a semiconductor with conductivity of 4,339 S/m. A conductive model of C12A7:C crystal was established to study its conductive mechanism. Through theoretical calculations of the conductive structure model, the density of states and transfer function are important factors determining the conductivity of C12A7:C crystals. Based on the analysis of these two factors, C is the key to electron transfer in the C12A7:C crystal. Further research indicates that the C–C bond is the main form of C in C12A7:C crystals. These C–C bonds satisfy the formation conditions of conjugated systems and are key to the conductivity of C12A7:C crystals. Through simulation calculations, the volt ampere characteristic curve of C12A7:C exhibits Ohmic conductor characteristics. The conductivity of C12A7:C obtained through theoretical calculation is consistent with the experimental results. In conclusion, the conductivity of C12A7:C crystal is mainly due to the C–C conjugated system formed by carbon atoms in the crystal.

Abstract To systematically analyze the damage caused by bedrock and overburden layer slope under seismic action, a set of large-scale shaking table test was designed and completed. Interpolation of the acceleration amplification coefficient, Hilbert–Huang transform and transfer function was adopted. The damage mechanisms of the bedrock and overburden layer slopes under seismic action are systematically summarized in terms of slope displacement, acceleration field, vibration amplitude, energy, vibration frequency, and damage level. The results show a significant acceleration amplification effect within the slope under seismic action and a localized amplification effect at the top and trailing edges of the slope. With an increase in the input seismic intensity, the difference in the vibration amplitude between the overburden layer and bedrock increased, low-frequency energy of the overburden layer was higher than that of the bedrock, and the vibration frequency of the overburden layer was smaller than that of the bedrock. These differences cause the interface to experience cyclic loading continuously, resulting in the damage degree of the overburden layer at the interface being larger than that of the bedrock, reduction of the shear strength, and eventual formation of landslides. The displacement in the middle of the overburden is always greater than that at the top. Therefore, under the action of an earthquake and gravity, the damage mode of the bedrock and overburden layer slope is such that the leading edge of the critical part pulls and slides at the trailing edge, and multiple tensile cracks are formed on the slope surface.

Abstract SARS‐CoV‐2 epidemic (severe acute respiratory corona virus 2 syndromes) has caused major impacts on a global scale. Several countries, including India, Europe, U.S.A., introduced a full state/nation lockdown to minimise the disease transmission through human interaction after the virus entered the population and to minimise the loss of human life. Millions of people have gone unemployed due to lockdown implementation, resulting in business and industry closure and leading to a national economic slowdown. Therefore, preventing the spread of the COVID‐19 virus in the world while also preserving the global economy is an essential problem requiring an effective and immediate solution. Using the compartmental epidemiology S, E, I, R or D (Susceptible, Exposed, Infectious, Recovery or Death) model extended to multiple population regions, the authors predict the evolution of the SARS‐CoV‐2 disease and construct an optimally scheduled lockdown calendar to execute lockdown over phases, using the well‐known Knapsack problem. A comparative analysis of both classical and quantum models shows that our model decreases SARS‐CoV‐2 active cases while retaining the average global economic factor, Gross Domestic Product, in contrast to the scenario with no lockdown.

To systematically analyze the damage caused by bedrock and overburden layer slope under seismic action, a set of large-scale shaking table test was designed and completed. Interpolation of the acceleration amplification coefficient, Hilbert–Huang transform and transfer function was adopted. The damage mechanisms of the bedrock and overburden layer slopes under seismic action are systematically summarized in terms of slope displacement, acceleration field, vibration amplitude, energy, vibration frequency, and damage level. The results show a significant acceleration amplification effect within the slope under seismic action and a localized amplification effect at the top and trailing edges of the slope. With an increase in the input seismic intensity, the difference in the vibration amplitude between the overburden layer and bedrock increased, low-frequency energy of the overburden layer was higher than that of the bedrock, and the vibration frequency of the overburden layer was smaller than that of the bedrock. These differences cause the interface to experience cyclic loading continuously, resulting in the damage degree of the overburden layer at the interface being larger than that of the bedrock, reduction of the shear strength, and eventual formation of landslides. The displacement in the middle of the overburden is always greater than that at the top. Therefore, under the action of an earthquake and gravity, the damage mode of the bedrock and overburden layer slope is such that the leading edge of the critical part pulls and slides at the trailing edge, and multiple tensile cracks are formed on the slope surface. [ABSTRACT FROM AUTHOR]

The problem of finding the arrangement of closed-loop control system poles that minimizes an objective function is considered. The system optimality criterion is the value of the H∞ norm of the frequency transfer function relative to the disturbance with constraints imposed on the system pole placement and the values of the H∞ norm of the sensitivity function and the transfer function from measurement noise to control. An optimization problem is formulated as follows: the vector of variables consists of the characteristic polynomial roots of the closed loop system with the admissible values restricted to a given pole placement region; in addition to the optimality criterion, the objective function includes penalty elements for other constraints. It is proposed to use a logarithmic scale for the moduli of the characteristic polynomial roots as elements of the vector of variables. The multi-extremality problem of the objective function is solved using the multiple start procedure. A coordinate descent modification with a pair of coordinates varied simultaneously is used for search. [ABSTRACT FROM AUTHOR]

Although healthcare and medical technology have advanced significantly over the past few decades, heart disease continues to be a major cause of mortality globally. Electrocardiography (ECG) is one of the most widely used tools for the detection of heart diseases. This study presents a mathematical model based on transfer functions that allows for the exploration and optimization of heart dynamics in Laplace space using a genetic algorithm (GA). The transfer function parameters were fine-tuned using the GA, with clinical ECG records serving as reference signals. The proposed model, which is based on polynomials and delays, approximates a real ECG with a root-mean-square error of 4.7% and an R 2 value of 0.72 . The model achieves the periodic nature of an ECG signal by using a single periodic impulse input. Its simplicity makes it possible to adjust waveform parameters with a predetermined understanding of their effects, which can be used to generate both arrhythmic patterns and healthy signals. This is a notable advantage over other models that are burdened by a large number of differential equations and many parameters. [ABSTRACT FROM AUTHOR]

In this study, we propose a novel backward shift algorithm for pole estimation of linear time‐invariant (LTI) systems. By making adjustments, we address the question: How should the frequencies of input signals be chosen? We select the frequencies based on algebraic accuracy in the numerical integral and use the Gaussian–Legendre formula in this process. After poles are located, the discrete Fourier transform (DFT) and the new backward shift algorithm (new BSA) along with the least squares (LS) method are used to identify the systems. Two examples show that the proposed method for pole estimation performs better and the corresponding identification algorithm is practical. [ABSTRACT FROM AUTHOR]

Copyright of Advances in Earth Science (1001-8166) is the property of Advances in Earth Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to detect the underground medium with large depth, the transmitter of electromagnetic sounding instrument has higher and higher power and voltage. A novel voltage equalizing strategy for cascaded constant current power supply using in electromagnetic transmitter was proposed in this paper. The cascaded topology of the transmitter has two isolated full‐bridge AC/DC converters, which had same input source and were connected in series on the output side. The mathematical model based on state space average method was analyzed. After simplifying the circuit, the state space equation was used to describe the circuit model. The stability and frequency characteristics of the system were analyzed. Aiming at the constant current output and the output voltage balance of the two converters, the system coupling model was established. The constant current controller and voltage equalizing controller were designed with decoupling method. A 300 W prototype was built and the experimental results verified the performance of the proposed method. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Ride comfort and handling are two important criteria regarding vehicle vibration control. For solving the inconsistency between ride comfort and handling, a semi-active suspension system equipped with a road classification system can be a suitable solution. Because the road condition varies during driving, the control gain of the semi-active suspension system should be adaptively changed according to the road level. In this paper, accelerometer data and a transfer function scheme will be used for road classification, and there is no need to measure the road directly with difficult and often expensive methods. In this approach, a transfer function that makes relevant the Power Spectral Density (PSD) of the road surface and the PSD of car acceleration is used. Road classification is investigated for a vehicle with a nonlinear, semi-active suspension system equipped with Continuous Damping Control (CDC) and nonlinear springs. To show the applicability of the proposed method in scenarios close to real situations, robustness analysis is done by considering vehicle model uncertainties and sensor noise. The simulation results show that the proposed method is robust against typical uncertainties and accelerometer noise and can classify the road level, which is used to tune the parameters of the nonlinear, semi-active suspension system. [ABSTRACT FROM AUTHOR]

Export is one of the factors that increase the economic growth of a country. One measure of export activity that can describe economic growth in Indonesia is The Export Unit Value Index, which is an index that measures changes in the price of export commodities sold by residents of one country to residents of other countries. The purpose of this study is to predict the unit value index of exports in Indonesia using a single input transfer function model and to see the influence of the value of oil and gas and non-oil and gas exports on the unit value index of exports in Indonesia. The single input transfer function model is a model that describes the future forecast of a series (output series) obtained based on the past values of the output series and other time series (input series) that affect the output series. The results of this study obtained a transfer function model with the order (0,0,1) with a noise series following ARIMA (1,0,1). Based on this model, the export unit value index at time t is influenced by the unit value export index in the previous month and is influenced by the oil and gas and non-oil and gas export value in the same month. As indicated by its MAPE value of 4.89%, the forecast value does not diverge much from the actual value, which suggests that the transfer function model can be used to predict the export unit value index in Indonesia. [ABSTRACT FROM AUTHOR]

In response to land use challenges, major urban centers have started implementing over-track building constructions above metro lines as a means of accommodating residents and workers. However, the continuous operation of trains can generate excessive vibrations that may negatively impact the overall living conditions for occupants residing in these structures. In this paper, vibration measurements were conducted on the soil and within a three-story frame structure building. Additionally, a three-dimensional finite element model of the track–soil–building was established. The wheel–rail contact force was incorporated as a dynamic load that varies with time to accurately simulate the vibration response induced by trains. According to the construction process of the over-track building, four construction stages were set up using the finite element model to study the impact of the construction stages on the vibration propagation from the soil to building structure. The results indicate that the presence of existing structures exerts a mitigating influence on soil vibrations. Pile foundation construction can effectively mitigate soil vibration to a significant extent. The findings provide references for the future development and design of over-track buildings. [ABSTRACT FROM AUTHOR]

Recently, a considerable amount of research has been conducted on MRF-based clutches or actuators due to the significant role such device plays in torque coupling and control applications. It is desired to find an accurate yet quick dynamic analytical model to design the electrical circuit of MR clutch. The previous researches on the dynamic response of MR devices have focused on the magnetic response, while less on the current response, mostly on experimental test aspects. Aim at this issue, considering the combination of driving electronics and excitation coil, this study proposes the analytical model from command voltage to excitation current for electrical circuit of MR clutch for the first time. The analytical model develops first principle and is capable of accounting for driving electronics topology and coil configuration. The feasibility of the model was verified by experimental results. Moreover, the model has been implemented to investigate the effect of specific parameters on the electrical circuit dynamic of MR device. As mentioned above, the proposed analytical model provides comprehensive details for optimal design and improvement of circuit performance of MR devices. [ABSTRACT FROM AUTHOR]

Although body fluid volume control by the kidneys may be classified as a long-term arterial pressure (AP) control system, it does not necessarily follow that the urine flow (UF) response to changes in AP is slow. We quantified the dynamic characteristics of the UF response to short-term AP changes by changing mean AP between 60 mmHg and 100 mmHg every 10 s according to a binary white noise sequence in anesthetized rats (n = 8 animals). In a baro-on trial (the carotid sinus baroreflex was enabled), the UF response represented the combined synergistic effects of pressure diuresis (PD) and neurally mediated antidiuresis (NMA). In a baro-fix trial (the carotid sinus pressure was fixed at 100 mmHg), the UF response mainly reflected the effect of PD. The UF step response was quantified using the sum of two exponential decay functions. The fast and slow components had time constants of 6.5 ± 3.6 s and 102 ± 85 s (means ± SD), respectively, in the baro-on trial. Although the gain of the fast component did not differ between the two trials (0.49 ± 0.21 vs. 0.66 ± 0.22 lL·min-1·kg-1·mmHg-1), the gain of the slow component was greater in the baro-on than in the baro-fix trial (0.51 ± 0.14 vs. 0.09 ± 0.39 lL·min-1·kg-1·mmHg-1, P = 0.023). The magnitude of NMA relative to PD was calculated to be 32.2 ± 29.8%. In conclusion, NMA contributed to the slow component, and its magnitude was approximately one-third of that of the effect of PD. [ABSTRACT FROM AUTHOR]

Electromagnetic (EM) parametric modeling has become significant for EM designs of microwave devices. This paper outlines recent advances in hybrid format‐based neuro‐transfer function (TF) techniques for EM parametric modeling of microwave devices. To solve the problem of high‐sensitivity, a novel decomposition approach is discussed to develop a rational‐based neuro‐TF model of EM behavior of microwave devices. To handle the issue of non‐smoothness and discontinuity, a parametric modeling technique incorporating pole‐residue/rational and neural network hybrid transfer function (short for rational/pole‐residue hybrid neuro‐TF) of EM behavior is reviewed. This technique effectively combines rational and residue‐pole formats of the transfer functions. Compared with the residue‐pole‐based neuro‐TF modeling approach and the rational‐based neuro‐TF modeling approach, the rational/pole‐residue hybrid neuro‐TF technique allows for better accuracy in large geometrical changes and high order applications. A parametric modeling method combining neural network and polynomial‐transfer function (neuro‐PTF) is further presented as an advanced version of the rational/pole‐residue hybrid neuro‐TF method. In this approach, the pole–residue‐based transfer function and the polynomial function are used together to describe the EM responses, and can produce more accurate models, especially with large geometrical variables. Following the modeling process, trained models can be used to provide fast and accurate EM response predictions and can subsequently be used for advanced circuit and system design. [ABSTRACT FROM AUTHOR]

In view of the problem that the measurement equation and transfer function of the traditional closed loop decoding algorithm are easy to cause steady state errors during acceleration, an improved closed - loop decoding algorithm is proposed in this study. Before the closed loop solution, the least square method is used to fit the output signal parameters of the rotating transformer to obtain a more accurate signal of the rotating transformer. The calibration device is designed to avoid the influence of parameter fluctuation and nonlinear factors on the system performance and enhance the stability of the system. The steady state error, angular position error and angular velocity error of the decoding algorithm are analyzed by simulation experiment. The results show that the improved closed - loop decoding algorithm is more stable and the steady state error is smaller. Angular position error fluctuation from (10,0) to (-4.0,3.5), the angular velocity error fluctuation from (-0.50, -0.25) to (-0.15,0.10). [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mechanical Strength / Jixie Qiangdu is the property of Zhengzhou Research Institute of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Direct volume rendering (DVR) is a technique that emphasizes structures of interest (SOIs) within a volume visually, while simultaneously depicting adjacent regional information, e.g., the spatial location of a structure concerning its neighbors. In DVR, transfer function (TF) plays a key role by enabling accurate identification of SOIs interactively as well as ensuring appropriate visibility of them. TF generation typically involves non-intuitive trial-and-error optimization of rendering parameters, which is time-consuming and inefficient. Attempts at mitigating this manual process have led to approaches that make use of a knowledge database consisting of pre-designed TFs by domain experts. In these approaches, a user navigates the knowledge database to find the most suitable pre-designed TF for their input volume to visualize the SOIs. Although these approaches potentially reduce the workload to generate the TFs, they, however, require manual TF navigation of the knowledge database, as well as the likely fine tuning of the selected TF to suit the input. In this work, we propose a TF design approach, CBR-TF, where we introduce a new content-based retrieval (CBR) method to automatically navigate the knowledge database. Instead of pre-designed TFs, our knowledge database contains volumes with SOI labels. Given an input volume, our CBR-TF approach retrieves relevant volumes (with SOI labels) from the knowledge database; the retrieved labels are then used to generate and optimize TFs of the input. This approach largely reduces manual TF navigation and fine tuning. For our CBR-TF approach, we introduce a novel volumetric image feature which includes both a local primitive intensity profile along the SOIs and regional spatial semantics available from the co-planar images to the profile. For the regional spatial semantics, we adopt a convolutional neural network to obtain high-level image feature representations. For the intensity profile, we extend the dynamic time warping technique to address subtle alignment differences between similar profiles (SOIs). Finally, we propose a two-stage CBR scheme to enable the use of these two different feature representations in a complementary manner, thereby improving SOI retrieval performance. We demonstrate the capabilities of our CBR-TF approach with comparison with a conventional approach in visualization, where an intensity profile matching algorithm is used, and also with potential use-cases in medical volume visualization. [ABSTRACT FROM AUTHOR]

In the paper, a discrete dynamic model of a full-bridge resonant converter with a symmetrical operating mode has been obtained, which describes the resonant converter as a transfer link with an supply voltage input side and a load current output side. The dynamic model is based on a linear mathematical model of the resonant converter built according to the superposition principle. The structure of the resonant converter with the processes outline function is given and analyzed. The structure of the discrete dynamic model of the resonant converter of the nth order is presented. It is proved that the transfer function of the discrete dynamic model for the outline function can be determined by the transfer function of the continuous system. The resulting dependencies describing the discrete transfer functions of the resonant converter are used to obtain the discrete dynamic model of the double-circuit transformer resonant converter in a synchronous rectifier. For this, the sequence of actions is defined: definition of the transfer function of the continuous dynamic model; obtaining the system of equations in vector-matrix form describing electromagnetic processes in the converter; definition of the system of discrete equations; definition of the transfer function of the circuit. The obtained theoretical results were verified by means of simulation modeling of the considered double-circuit resonant converter. The proposed dynamic model makes it possible to analyze the influence of instability and low frequency fluctuations of the supply voltage of the resonant converter on the output values. The presented results can be used in the development and improvement of single- or multi-circuit bridge high-frequency resonant converters as the secondary power sources and converters used in ship demagnetization systems. References 25, figures 8, tables 2. [ABSTRACT FROM AUTHOR]

This article concerns the identification of a transfer function which contains principal design and dynamic parameters of a hydraulic viscous disc clutch operated and controlled by an electrorheological (ER) fluid as a working fluid. A mathematical model of clutch dynamics is created as part of the clutch identification. It is considered that the changes in torque over time are described by transfer function represented by the first-order system with time delay. A prototypic clutch and a test bench are constructed, and tests are performed. A high voltage step input is used to trigger the torque changes. Constant parameters of the first-order system with time delay are identified on the basis of bench tests. According to the values of these parameters, a proportional-integral (PI) controller is selected for the closed-loop control system. It is found that operation of such a control system utilizing the identified design parameters is acceptable with high accuracy under external disturbances. [ABSTRACT FROM AUTHOR]

In this study, the proportional-integral-derivative (PID) controller of a sample thermoelectric cooler(TEC)system model is optimized using four different metaheuristic optimization algorithms. For this aim, the classical PID and the metaheuristic optimization algorithms as Coronavirus Herd Immunity Optimization (CHIO), Atomic Search Optimization (ASO), Artificial Bee Colony (ABC) and Particle Swarm Optimization (PSO)were used for control of a TEC system. The settling time and maximum overshoot criteria are used to compare performances of the optimized controllers. -20°C is the desired temperature for the cold side of this thermoelectric module. Since TEC systems requirequick cooling, CHIO-PID performs the best because it is the first to reach the set temperature of -20 ̊C in 42 seconds at the 1% band limit.

The partial discharge （PD） of high-voltage cables and the accessories directly affects the insulation performance of power cables. Therefore， a PD detection method for high-voltage cables based on finite-difference time-domain （FDTD） modeling is proposed. First， the FDTD method and the theory of transfer function are introduced into the cable PD detection. Besides， the FDTD model of high-voltage cables is established， and the accuracy of the model is evaluated. Then， the original pulses used to excite PD events in the FDTD model of 11 kV XLPE （cross-linked polyethylene） cables are obtained， and the relevant steps of hybrid modeling for PD detection are elaborated. Finally， the finite element calculation results of the pulse injection test are analyzed to verify the effectiveness of the proposed method. The method， also applicable to the PD detection of EPR （ethylene propylene rubber） cables， paper-insulated cables， and other cables， helps to study the relationship between the PD signals and the excitation signals of PD sources.

The relevance of this study lies in the fact that it presents a mathematical model of the dynamics of the propulsion system of a ship that takes into consideration the mass of water added to it. The influence of this phenomenon on the resonant frequencies of the propeller shaft is examined, and a transfer function for a controllable-pitch propeller is obtained for various operating modes. The purpose of the study is to improve the calculation of the dynamic operating modes of a controllable-pitch propeller by examining the features of a visual models. The VisSim software package is used in the study. A visual model is developed that considers the influence of the rotational speed on the value of the rotational inertia attached to the variable-pitch screw of the mass of water, and a special transfer function is proposed. The study shows that a transfer function of this type has a loop enabling negative feedback. An analysis of the operation of the propeller shaft at its resonant frequency is conducted based on the application of frequency characteristics using the transfer functions obtained. We show that in the low-frequency region, a consideration of the added rotational inertia using the proposed transfer function leads to a significant difference compared to the result obtained with the existing calculation method.

During the fault period, a phase angle jump may occur at the stator or the point of common coupling, which will deteriorate the low-voltage ride-through (LVRT) characteristics of a doubly fed induction generator (DFIG). The existing LVRT studies focus on the impact of a voltage drop on DFIGs but often ignore that of a phase angle jump. The time-domain simulation is accurate in describing the response of a DFIG during the LVRT process, but it is time-consuming for a DFIG with the full-order model. In this paper, by using the voltage magnitude and phase angle of the stator or the point of common coupling as the inputs, and the state variables as the outputs, the transfer function of a DFIG is derived to analyze its response and find the LVRT measures against the voltage drop and, especially, the phase angle jump. Firstly, the differential-algebraic equations of the DFIG are linearized to propose their transfer function model. Secondly, considering its high-order characteristic, a model reduction method for the transfer function of the DFIG using the Schur decomposition is proposed, and the analytical expression of the output variables of the DFIG with the phase angle jump is derived by the inverse Laplace transformation to judge the necessity of the LVRT measures. Finally, the simulation results of the DFIG are provided to verify the accuracy of the transfer function model and its reduced-order form and validate the feasibility of the LVRT against the phase angle jump with the proposed models.

To solve the problems of difficult vibration sources simulation in the ground test of the on-orbit optical load, a multi-dimensional micro-vibration simulator based on the improved Gough–Stewart platform was designed, which can effectively reproduce the characteristics of wide frequency distribution and small vibration magnitude of space micro-vibration. The analytical formula was derived by using the virtual frequent principle and the Newton–Euler equation for the natural frequency of the system, and the simulator's configuration was optimized. The structure of legs was designed and optimized according to the optimal configuration parameters. Finally, the micro-vibration simulator was tested, and the test results showed that the output bandwidth of the simulator was 5–300 Hz and the maximum magnitude error was 8%, thus demonstrating the multi-dimensional micro-vibration simulation platform has the characteristics of large frequent bandwidth, high load carrying capacity, and small vibration magnitude. [ABSTRACT FROM AUTHOR]

External events are commonly known as interventions that often affect times series of counts. This research introduces a class of transfer function models that include four different types of interventions on integer-valued time series: abrupt start and abrupt decay (additive outlier), abrupt start and gradual decay (transient shift), abrupt start and permanent effect (level shift) and gradual start and permanent effect. We propose integer-valued transfer function models incorporating a generalized Poisson, log-linear generalized Poisson or negative binomial to estimate and detect these four types of interventions in a time series of counts. Utilizing Bayesian methods, which are adaptive Markov chain Monte Carlo (MCMC) algorithms to obtain the estimation, we further employ deviance information criterion (DIC), posterior odd ratios and mean squared standardized residual for model comparisons. As an illustration, this study evaluates the effectiveness of our methods through a simulation study and application to crime data in Albury City, New South Wales (NSW) Australia. Simulation results show that the MCMC procedure is reasonably effective. The empirical outcome also reveals that the proposed models are able to successfully detect the locations and type of interventions. [ABSTRACT FROM AUTHOR]

Direct volume rendering is widely used in scientific visualization. The transfer function largely determines the effect of rendering results. Explosion data is large-scale complex time-varying volume data. The value range and distribution of its pressure field will change drastically with time. In order to realize continuous tracking of shock wave propagation characteristics, this paper proposed an automatic transfer function design method based on scalar-temporal gradient (STG) 2D space. Combined with the physical laws in the explosion process, the method divided the STG space into multiple states and summarized the transition laws between states. It encoded the propagation characteristics of shock waves with state transition chains (STCs) of a certain length, called time-varying features. The color assignment in the transfer function took time-varying features as the basic unit, which was done automatically through a complete state transition chain. The opacity in the transfer function used a piecewise non-linear curve based on the pressure change rate, highlighting the characteristics of severe pressure changes. The paper selected two typical large-scale explosion scenarios to verify the method. The rendering results all contain a wealth of clearly distinguishable shock wave propagation characteristics. The results showed that the generated transfer function can stably and accurately capture the propagation characteristics of shock waves in the whole-time dimension. [ABSTRACT FROM AUTHOR]

Information relating to suspended sediment load is of particular importance in terms of water management and environmental protection schemes. The sediment rating curve (SRC) is used to express the common relation between suspended sediment load and flow discharge in a basin. SRC, however, does not consider the effect of time lag in flow discharge; instead, it makes a kind of bias in its estimation, toward overestimation or underestimation of a sediment load. In this direction, the current research aims to improve and extend the SRC model by using a transfer function method. The proposed method was applied to a specific basin to better capture the effect of time lag on suspended sediment load estimation. This function estimated the current sediment load in current time. Three case studies were conducted in different climate conditions of Iran to evaluate the application of transfer function with SRC in assessing the relation between flow and suspended sediment discharge. The results revealed that the transfer function method demonstrated high precision in forecasting suspended sediment load, as evidenced by its mean absolute difference (MADIF) and bias criterion calculations. The findings indicated that the proposed method could enhance the accuracy of sediment load estimations in basins with similar characteristics. This approach was based on an unbiased future forecast and provided a high level of confidence. The results suggested that this method could be successfully applied to other basins to improve the accuracy of sediment load estimations. [ABSTRACT FROM AUTHOR]

The article discusses the control system of the cone crusher of medium crushing and the possibility of its improvement. Based on the analysis of the existing approaches to the crusher, the parametric scheme of the crusher is obtained as a control object. The work does not address issues related to the regulation of the dispersed composition of the finished product. Therefore, the parametric scheme was simplified taking into account the cross-links between the level of raw materials in the crusher and the capacity of the crusher. Based on this, it mathematical model was developed. A model of an optimal crusher control system using a linear-quadratic regulator with elimination of static error by introducing an integral component is proposed. The results of the study of this model with different combinations of perturbations showed that it is suboptimal. Thus, this will allow the use of such a control system to automate the crusher, which will provide its work in optimal modes at different density of raw materials, as well as to a large extent ensure its accident-free operation and reduce wear of the crusher units. [ABSTRACT FROM AUTHOR]

In this paper we consider bounded-input-bounded-output (BIBO) stability of systems described by infinite-dimensional linear state-space representations, filling the so far unattended gap of a formal definition and characterization of BIBO stability in this general case. Furthermore, we provide several sufficient conditions guaranteeing BIBO stability of a particular system and discuss to which extent this property is preserved under additive and multiplicative perturbations of the system. [ABSTRACT FROM AUTHOR]

In this study, the proportional-integral-derivative (PID) controller of a sample thermoelectric cooler (TEC) system model is optimized using four different metaheuristic optimization algorithms. For this aim, the classical PID and the metaheuristic optimization algorithms as Coronavirus Herd Immunity Optimization (CHIO), Atomic Search Optimization (ASO), Artificial Bee Colony (ABC) and Particle Swarm Optimization (PSO) were used for control of a TEC system. The settling time and maximum overshoot criteria are used to compare performances of the optimized controllers. -20°C is the desired temperature for the cold side of this thermoelectric module. Since TEC systems require quick cooling, CHIO-PID performs the best because it is the first to reach the set temperature of -20 ˚C in 42 seconds at the 1% band limit. [ABSTRACT FROM AUTHOR]

In this paper, the fatigue state estimation of the metro bogie frame is discussed based on limited sensors through frequency domain methods. The middle-frequency and high-frequency vibration fatigue damage cases of one metro bogie frame is discussed. The main excitations come from the wheel/rail interactions including wheel out-of-roundness and rail irregularities. The most common modal vibration of the bogie frame, where the transom bending deformation is dominant, is taken as the research object to study the possibilities of fatigue failure monitoring on concerned points of the bogie frame transom focusing on specific transfer paths. To eliminate unnecessary input signals which are not closely related to the occurrence of large stress amplitudes, the coherence analysis of different loads including the transmission load, carbody load and wheel-rail impact load is conducted through various methods including the short-time Fourier transform spectrum analysis, the magnitude-squared coherence analysis and the partial directed coherence analysis. Then the power spectral densities (PSDs) of the measured accelerations and cross power spectral densities (CPSDs) are calculated to obtain the transfer functions, whose output is the Y -axis stress at the concerned point. The stress PSDs are obtained using the instantly measured input accelerations and the prepared transfer function. Then the spectral moments and the stress amplitudes distribution functions are calculated through the frequency domain method to overcome the computational burden. The stress reconstructions based on inverse fast Fourier transform are analyzed and the fatigue damage results show good consistency with the experimental ones. [ABSTRACT FROM AUTHOR]

It is shown that the vibration transfer and working medium pressure pulsations through vibration-isolating pipeline junctions of various plants may increase by two or three orders of magnitude with an increase in the vibration frequency and in the presence of incompressible working fluid. The results of research of the found physical models that determine this phenomenon are presented. The experimental results for a spatial three-component broadband active vibration-protection system (AVS) for vibration damping beyond the vibration isolation junction with liquid are considered. An experimental plant scheme for studying the simultaneous spatial active damping of dynamic forces, vibrations and pressure pulsations downstream from the junction has been given. Calculated dependences of the maximum efficiency of considered AVS on frequency are obtained. Efficient active damping of forces is shown to be attainable in an open loop without feedback. While damping in an open loop at the experimental plant, the efficiency of active damping of dynamic forces is obtained in three directions up to 10 dB or more in the frequency range from 5 to 800 Hz (more than seven octaves). The analysis of scientific publications reveals the uniqueness of this result. In this case, there are no zones of negative efficiency outside the active damping frequency range, which appear while using other methods of active damping. [ABSTRACT FROM AUTHOR]

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In the 21st century, researchers have been exploring different designs, performance characteristics, charging–discharging regions, and regenerative braking aspects of electric vehicles. However, there has been a major gap in the multimodal analysis of the accelerating pedal drive for electric vehicles; therefore, herein, a novel analytical model of a mimicked foot pedaling control of an electric vehicle is developed by cascading five sub-models (i.e., foot pedal, resistive potentiometer, 555 timer, buck converter, and the permanent magnet DC motor) to synthesize the overall third-order transfer function of the system. MATLAB is utilized to comprehensively analyze the transient and steady-state characteristics of the developed model by considering the pedaling force, four different materials (i.e., aluminum, brass, carbon fiber, and polyamide 6), the potentiometer's resistance, and the mechanical and electrical attributes of the motor. The results highlight that the linear pedaling drive is possible by considering the polyamide 6 material's pedaling properties of 0.25 kg mass and 2.679 Ns/m damping coefficient. Furthermore, at a lesser potentiometer track length (around 10 cm) and equivalent inertia of 5 Kgm2, the motor generates the regulated angular velocity, thereby minimizing the transient characteristics of the accelerating pedal. [ABSTRACT FROM AUTHOR]

The appropriate design of supports, upon which beams are usually placed as structural components in many engineering scenarios, has substantial significance in terms of both structural efficacy and cost factors. When beams experience various dynamic vibration effects, it is crucial to contemplate appropriate support systems that will effectively adapt to these vibrations. The present work investigates the most suitable support configuration for a cantilever beam, including viscoelastic supports across different vibration modes. Within this particular framework, a cantilever beam is simulated using beam finite elements. The beam is positioned on viscoelastic supports, which are represented by simple springs and damping elements. These supports are then included in the overall structural model. The equation of motion for the beam is first formulated in the temporal domain and then converted to the frequency domain via the use of the Fourier Transform. The basic equations used in the frequency domain are utilized to establish the dynamic characteristics of the beam by means of transfer functions. The determination of the ideal stiffness and damping coefficients of the viscoelastic components is achieved by minimizing the absolute acceleration at the free end of the beam. In order to minimize the objective function associated with acceleration, the nonlinear equations derived from Lagrange multipliers are solved using a gradient-based technique. The governing equations of the approach need partial derivatives with respect to design variables. Consequently, analytical derivative equations are formulated for both the stiffness and damping parameters. The present work introduces a concurrent optimization approach for both stiffness and damping. Passive constraints are established inside the optimization problem to impose restrictions on the lower and higher boundaries of the stiffness and damping coefficients. On the other hand, active constraints are used to ascertain the specific values of the overall stiffness and damping coefficients. The efficacy of the established approach in estimating the ideal spring and damping coefficients of viscoelastic supports and its ability to provide optimal support solutions for various vibration modes have been shown via comparative experiments with prior research. [ABSTRACT FROM AUTHOR]

Classification of medical data is largely dependent on the effective identification of key features of the data that can be used to aid in the diagnosis of related diseases. This goal can be achieved through feature selection methods that endeavor to get rid of redundant and irrelevant features to ameliorate classification accuracy. This is the aim of this work where a new meta-heuristic, referred to as snake optimizer, was adopted for the purpose of boosting the performance of existing feature selection methods. This optimizer may smoothly fall into local optimal solutions, which may present weak search performance and slow convergence speeds in handling feature selection problems. On this basis, this paper presents three improved adaptive versions of this optimizer, each of which has increased search performance over the basic optimizer. This optimizer was improved using three mathematical models named exponential, power, and delayed S-shaped, to create three methods, referred to as exponential, power, and delayed S-shaped snake optimizers, respectively. These proposed versions were also matured to have more balance between exploration and exploitation aspects. Then, binary variants of these optimizers were evolved to solve feature selection problems using the k-nearest neighbor classifier. To verify the efficacy of these binary optimizers, 24 datasets were used, and then compared with other feature selection optimizers. The experimental results obviously manifested the efficiency of the proposed optimizers in realizing the optimal feature set by achieving utmost accuracy and minimal number of features in the majority of the studied datasets. The proposed binary power snake optimizer outperformed all other competitors in 13, 10, 8, 8, and 12 datasets in respect of classification accuracy, number of chosen attributes, specificity, sensitivity, and fitness scores, respectively. Out of the 24 datasets taken into consideration, the results on 12, 6, and 8 datasets, respectively, showed that this proposed optimizer presented performance scores of more than 90% in respect of sensitivity, accuracy, and specificity metrics. [ABSTRACT FROM AUTHOR]