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The X ̄ type charts possess a drawback as they may falsely indicate out-of-control (OOC) situations when the process standard deviation is unstable. They are not robust against estimation errors or variations in the process standard deviation. To overcome this setback, the t type charts were developed. This research introduces the variable parameters (VP) t chart for effectively monitoring the process mean. This study encompasses the implementation, optimal designs and performance evaluation of the proposed VP t chart. The average time to signal (ATS), standard deviation of the time to signal (SDTS) and expected average time to signal (EATS) criteria are used to assess and compare the performance of the VP t chart with existing charts, such as Shewhart (SH) t , synthetic (Syn) t , side-sensitive group runs (SSGR) t , exponentially weighted moving average (EWMA) t and variable sampling interval (VSI) EWMA t charts. From extensive analysis, we observe that the VP t chart outperforms the SH t , Syn t and SSGR t charts for all sizes of mean shifts. However, the EWMA t and VSI EWMA t charts exhibit better performance for small shifts. Additionally, to demonstrate the implementation and usage of the proposed VP t chart, we present a real-world manufacturing example. [ABSTRACT FROM AUTHOR]

Copyright of Materiały Budowlane is the property of Wydawnictwo SIGMA-NOT 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.)

We study the material composition of a ferromagnesian oxidized nickel ore of the Serov deposit. According to the results of chemical analysis, it was found that the studied ore is poor in the nickel content. Note that magnesium and iron are present in the ore as macroimpurities. The main nickel-containing minerals are lizardite and clinochlore; smaller amounts of nickel are contained in talc. To determine the optimal technological parameters of heap leaching and reveal their correlation dependences, we use the mathematical method of data processing, namely, the Box–Wilson steep ascent method. Based on the results of leaching, we compute the values of the efficiency criterion and the variance of the efficiency criterion and deduce a regression equation for the description of the process of leaching. The adequacy of the regression equation is established by using the Fisher criterion. The results of mathematical processing of the experimental data show that the concentration of sulfuric acid in the solution, the pause between irrigations, and the specific consumption of the leaching solution exert a significant effect on the efficiency of leaching in the stage of nickel extraction from 0–30%. On the basis of computed values of the efficiency criterion, we determine the values of variable parameters for the second stage of determination of the optimal conditions of leaching guaranteeing the efficient ore opening in the stage of nickel extraction up to 30%. [ABSTRACT FROM AUTHOR]

In this investigation, a series of WO3 samples were achieved by a ball milling treatment under variable synthetic parameters (milling time from 0.5 to 8 h, grinding speed from 100 to 500 rpm, and several solvents as dispersants). These samples were characterized by X-ray diffraction patterns, ultraviolet-visible diffuse reflection spectra, scanning electron microscope, and photoluminescence spectra. It was found that the extension of milling time, increase in grinding speed, and suitable dispersant favored the reduced particles size and crystallinity, and enlarged band gap energies, thus benefiting the separation of charge carriers and photocatalytic removal of NO under visible light. Under the suitable condition, the best prepared candidate could removal NO molecules about 45% upon visible light irradiation. Eventually, the good conservation of photocatalytic performance and structural stability identified the robust nature of prepared samples, and a possible photocatalysis mechanism was proposed. [ABSTRACT FROM AUTHOR]

In this paper, new results on the α -fractal function with variable parameters are presented. The Weyl–Marchaud variable order fractional derivative of an α -fractal function with variable parameters is examined by imposing certain conditions on the scaling factors. Following the investigation of fractional derivative, the definite integral of the α -fractal function with variable parameters is evaluated for various intervals in the prescribed domain. Finally, an explicit structure for the α -fractal function is provided using the base q representation of numbers. [ABSTRACT FROM AUTHOR]

In order to significantly reduce the defects of hole-making on Carbon Fiber Reinforced Plastics (CFRP), a scheme on the variable parameter helical milling experiments was carried out. First, the helical milling process was analyzed. Second, using the response surface methodology (RSM) in the experiments, the max exit tear value, aperture diameter and surface roughness Ra at the intermediate area were analyzed and the optimum combination of parameters was obtained: spindle speed 8962 r/min, helical speed 60 r/min, and pitch 0.207 mm at the hole entry and exit areas; spindle speed 6242 r/min, helical speed 87 r/min, and pitch 0.205 mm at the hole intermediate area. Last, the effect of milling direction on hole-making was obtained: up milling at the hole entry and exit areas and down milling at the hole intermediate area. The superiority of variable parameter helical milling experiment was verified: there were fewer defects such as burrs and tears at hole entry and exit areas; and the surface roughness Ra was 6.39% lower, the aperture deviation was from + 0.011 mm to -0.007 mm at the hole intermediate area. Therefore, the quality of hole-making by the variable parameter helical milling scheme was significantly improved. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai University of Engineering Science / Shanghai Gongcheng Jishu Daxue Xuebao is the property of Journal of Shanghai University of Engineering 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.)

This paper improves the sensitivity of the existing run sum chart for shifts in the coefficient of variation $$\left(\gamma \right)$$ γ by proposing two types of adaptive schemes, i.e. the variable sample size and sampling interval (VSSI) and variable parameter (VP) schemes. The VSSI run sum $$\gamma $$ γ chart varies the sample size $$\left(n \right)$$ n and sampling interval $$\left(h \right)$$ h , while the VP run sum $$\gamma $$ γ chart varies not only n and h but also the size of each region of the run sum chart. The operations, as well as formulae and algorithms to optimize the charts' performance, are developed. Subsequently, tables of optimal charting parameters are obtained. The VP run sum $$\gamma $$ γ chart is shown to outperform the VSSI run sum $$\gamma $$ γ chart. The proposed charts are also shown to outperform the variable sampling interval (VSI) run sum, variable sample size (VSS) run sum, and the VSSI, VSS and VSI $$\gamma $$ γ charts, as well as the VSS and VSI EWMA $${\gamma ^2}$$ γ 2 charts for moderate and large shift sizes. Implementation on an actual industrial example shows the sensitivity of the proposed charts towards small shifts. [ABSTRACT FROM AUTHOR]

In this paper, we propose an optimal fractional-order accumulative Grey Markov model with variable parameters (FOGMKM (1, 1)) to predict the annual total energy consumption in China and improve the accuracy of energy consumption forecasting. The new model is built upon the traditional Grey model and utilized matrix perturbation theory to study the natural and response characteristics of a system when the structural parameters change slightly. The particle swarm optimization algorithm (PSO) is used to determine the number of optimal fractional order and nonlinear parameters. An experiment is conducted to validate the high prediction accuracy of the FOGMKM (1, 1) model, with mean absolute percentage error (MAPE) and root mean square error (RMSE) values of 0.51% and 1886.6, respectively, and corresponding fitting values of 0.92% and 6108.8. These results demonstrate the superior fitting performance of the FOGMKM (1, 1) model when compared to other six competitive models, including GM (1, 1), ARIMA, Linear, FAONGBM (1, 1), FGM (1, 1) and FOGM (1, 1). Our study provides a scientific basis and technical references for further research in the finance as well as energy fields and can serve well for energy market benchmark research.

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology 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.)

Titanium alloy was widely used in various tubing systems due to the excellent performance, and tubes were usually used as a connection channel for conveying media with holes. However, the stability and dependability of media transmission in the tubing system would be directly impacted by the quality of the holes. This study primarily focused on TC4 titanium alloy tubes to investigate variable parameter helical milling holes to enhance the quality of tube connection holes. The finite element method simulation and response surface method were used to examine the relationship between each process parameter and the accuracy of the holes. Thus, a better combination of process parameters was projected. And based on this, a variable parameter hole-making scheme was proposed to lower the burrs at the entrance and exit of holes and enhance the quality of the wall of holes. The results showed that the aperture of 5.015 mm after processing the titanium alloy tube using the better process parameters met the requirements of H8. Additionally, the burrs at the hole entrance were 1.4 μm, the burrs at the hole exit were not noticeable, and the surface roughness Rz and Ra were 1.459 μm and 0.232 μm, respectively, met the requirements of process technology. The variable parameter helical milling technique used in this study could significantly raise the quality of holes produced in titanium alloy tubes and serve as a valuable benchmark for tubes of other materials. [ABSTRACT FROM AUTHOR]

During the process of designing new devices for the high-speed metallization process, there appears the necessity to define the stable operation range and search for the optimum values of the operation mode and design parameters. This paper describes a process of optimization of a device made for depositing low-melting metal coatings, based on the rocket chamber operation principle. The paper presents an analysis of the objective function surface response metallizer operation performance. On the basis of this analysis the optimal values of fuel mass flow rate and excess oxidant ratio were determined. The choice of fuel and oxidizer throttling orifice cross-section areas was substantiated, the value of the throat cross-section for the metallizer flow-path was found. The expected performance of the designed device was also determined.

In this article, an extended and more generalized method of homotopy analysis method (HAM), known as q-homotopy analysis transform method (q -HATM) is employed to develop solutions for highly nonlinear form of various time-fractional advection-dispersion models (TFADE). The proposed methodology of q -HATM is a conjunction of two different strong methodologies, that are HAM and Laplace transform technique (LTT) which makes the scheme much more capable to develop the convergent series solutions for differential equations with high nonlinearity. In this work, two different examples are constructed for the nonlinear time-fractional form of dispersion models corresponding to distance dependent dispersion and velocity components and also for the time dependent decay rate system and solutions are constructed by using q -HATM in generalized form. The graphical comparison is made for different types of variable functions and also for the different fractional order indexes. Prominent impact of fractional derivative indexes is significantly observed over both the examples of dispersion models. Hence, proposed examples shows that the q -HATM is much convenient to handle the nonlinear systems of fractional models. [ABSTRACT FROM AUTHOR]

When constant parameters are used for peripheral milling CFRP, it is difficult to meet the requirement of high quality, so variable parameters machining is proposed. First, the response surface method was used to explore the effect of changing cutting conditions on the interaction of spindle speed, cutting depth and feed speed on radial force. The surface topography and roughness after the test were observed and analyzed. The results show that defects are more likely to occur at the entrance and the exit area than the central area. Taking the minimum radial force as the experimental goal, the optimal parameters combination was obtained and used for finite element and experimental verification. Second, the variable parameters milling were used the cemented carbide tool and PCD tool. The radial force, surface topography and roughness were analyzed and the optimized variable parameters combination was obtained. The results show that the high spindle speed, low feed speed and low cutting depth are beneficial to improve the surface quality at the entrance and the exit area when the machining parameters at the centra area remain unchanged. Meanwhile, when the parameters change abruptly, the fluctuation of the radial force at the variable parameters area is decreased. The variable parameters compared to constant parameters, the surface roughness of the machining with the cemented carbide tool at the entrance area by 29.7% and 7.4%, respectively and the machining with PCD tool at the exit and the entrance area decreased by 60.5%, 43.5% and 38.8%, 51.9%, respectively. Compared with the cemented carbide tool, the radial force of the PCD tool is more stable and the surface quality is further improved. [ABSTRACT FROM AUTHOR]

Abstract The feature map is a characteristic of high computational efficiency, but it is seldom used in path planning due to its lack of expression of environmental details. To solve this problem, a global path planning algorithm based on the feature map is proposed based on the directionality of line segment features. First, the robot searches the path along the direction of the target position but turns to search in the direction parallel to the obstacle, which it approaches until the line between the robot and the target position does not intersect with obstacles. Then it turns to the target position, keep searching the path. Meanwhile, the problems of the direction selection of turning point, corner point and obstacle circumvention in the searching process are analysed and corresponding solutions are put forth. Finally, a path optimisation algorithm with variable parameters is proposed, making the optimised path shorter and smoother. Simulation experiments demonstrate that the proposed algorithm is superior to A* algorithm in terms of computation time and path length, especially of the computation efficiency. The cover image is based on the Research Article A global path planning algorithm based on the feature map by Peng Liu et al., https://doi.org/10.1049/csy2.12040.

This article investigates the peristaltic flow of a hyperbolic tangent fluid with variable viscosity and thermal conductivity through a vertical asymmetric channel. Consideration is given to the effects of viscous dissipation, chemical reactions, and convection heat at the channel walls. The relevant mathematical modeling incorporates lubrication approximation. The resulting system of highly non-linear differential equations is converted non-dimensional via suitable quantities. The non-dimensional parameters formed in viscosity or thermal conductivity are treated as variables. This treatment is the fundamental recommendation of the current study to avoid obtaining unrealistic results. Using the built-in package (ParametricNDSolve) in the computing program Mathematica, the analysis is performed numerically, and the results for temperature and concentration profiles in addition to the trapping phenomenon are shown through graphs. The major findings show that an increase in temperature is associated with a decrease in viscosity, whereas the opposite (unrealistic) behavior is maintained when the variable parameters are treated as constants. Results also indicate that the thermal conductivity at relatively low temperatures is enhanced, whereas the opposite trend is noted at higher temperature values. Potential applications for the current work include cooling techniques used in medical and industrial applications, food processing, and blood flow in microvessels.

Copyright of Journal of Refrigeration is the property of Journal of Refrigeration 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.)

To ensure assembly accuracy and efficiency, the holes are made directly on the laminated material composed of CFRP and Al alloys. However, due to the sudden change of axial force in the transition area with different laminated sequence, a method of micro-lifting tool was proposed. First, the motion of helical milling was analyzed. The level values of influence the quality of the hole-making are determined, such as spindle speed, pitch, and preload. The response surface method (RSM) was used to design experiments, and the burr height between Al alloy interlayer and the tear value of CFRP was used as the standard to analyze the experimental results. The optimal parameter combination for different laminated sequences were predicted and used for cutting force analysis. The results show that sudden increase in cutting force is prone to occur in the transition area. Secondly, the hole-making processes with variable parameters study were carried out, and the method of micro-lifting tool is proposed for the experimental study of the sudden change of axial force in the transition between interlayer with constant parameters. The results show that the aperture of the hole-making with variable parameters of the laminated materials using the optimal process parameters all meets the H9. The interlayer burr of the Al alloy and the tear value of the CFRP at the entrance and exit conform to the technical requirements. The hole-making axial forces of CFRP and Al alloy are less than 50 N and 60 N, which are 70% and 83% of constant parameters milling. [ABSTRACT FROM AUTHOR]

The influence of three different states on the thermoacoustic instability characteristics of Rijke tube was compared in order to reseach the influencing factors of thermoacoustic oscillation by using the Rijke tube model with stack as the heat source. The thermoacoustic oscillations are numerically simulated from the start-up to the saturation state, and the effects of the temperature on the dynamic viscosity and the thermal conductivity are compared. The results show gravity has a greater influence than the thermoacoustic oscillation caused by thermal buoyancy, and it is related to the inner balance of the tube after the gravity and the temperature gradient caused by the protrusion and the temperature gradient caused by the reduction of the amplitude dissipation. For the comprehensive comparison of the two variable parameters, it is found that when the viscosity coefficient changes with temperature and the thermal conductivity is a fixed value, both of them decrease by 49.5% with the temperature change rate. This result far exceeds the viscosity coefficient itself influences.

In the hole making process, CFRP often has defects such as burrs and tears. Especially, it is more difficult to make high-quality and high-efficiency holes in thick-section CFRP which has a negative effect on its application. Based on the analysis of the mechanism of helical milling, the orthogonal experiments on the 24-mm Carbon Fiber Reinforced Plastics (CFRP) that affect the quality of hole making, such as spindle speed, feed per tooth, and number of blade teeth were conducted. The influence of process parameters on the quality of hole making was analyzed. Finally, the range analysis method was used to obtain the optimal hole-making parameters: spindle speed is 4500 rpm, feed per tooth is 0.02 mm/z, the number of blade teeth is 2. Based on the obtained optimal parameters, a novel hole making process with variable parameters was proposed, and two groups of parameter combinations were designed. Through the analysis of the hole morphology, surface roughness, axial force, and aperture deviation after the experiment, it is concluded that hole making process with variable parameters can meet the technical requirements of thick-section CFRP. [ABSTRACT FROM AUTHOR]

Among adaptive charts, the variable parameters chart shows the best performance as it varies all charting parameters. The existing variable parameters chart is designed by assuming that process parameters are known. However, process parameters are rarely known but are usually estimated based on Phase-I data. Hence, the variable parameters ... chart with estimated parameters is proposed. Formulae to evaluate various performance measures are derived through Markov chains. This paper shows that adopting the optimal charting parameters by incorrectly assuming that process parameters are known results in a large deterioration on the actual performance, especially for small shifts, a small number of subgroups, and small sample sizes. Subsequently, this paper proposes algorithms to obtain the optimal charting parameters for estimated parameters that show better performance, especially for small shift sizes, number of subgroups, and sample sizes. Finally, from an illustrative example, the proposed variable parameters ... chart is able to detect more out-of-control samples. [ABSTRACT FROM AUTHOR]

In this paper, a new variable parameters chart for the process mean with a statistic that integrates information from the study and auxiliary variables is proposed. The proposed variable parameters chart with auxiliary information (AI) (abbreviated as VP-AI) is optimally designed to minimize the out-of-control steady-state (i) average time to signal (ATS1) and (ii) expected average time to signal (EATS1) values when the mean shift sizes are known and unknown, respectively. The Markov chain approach is adopted to derive the formulae of the performance measures ATS1, standard deviation of the time to signal (SDTS1) and EATS1. The VP-AI chart significantly outperforms the standard VP chart; thus, justifying the incorporation of auxiliary information to enhance the ability of the VP chart. The VP-AI chart is also compared with the Shewhart AI, synthetic AI, exponentially weighted moving average (EWMA) AI, run sum AI and variable sample size and sampling interval (VSSI) AI charts. The VP-AI chart significantly outperforms the Shewhart AI, synthetic AI and VSSI AI charts for all levels of shifts. Meanwhile, the VP-AI chart outperforms the EWMA AI and run sum AI charts for most shifts. The VP-AI chart is found to be more robust than the EWMA-AI chart when the correlation coefficient is misspecified or the bivariate normality assumption is violated as long as the size of the shift is moderate or large. A real application which monitors spring elasticity is used to illustrate the VP-AI chart's implementation. [ABSTRACT FROM AUTHOR]

In order to study the creep behavior of surrounding rock of Huaying Coal Mine in Sichuan under different confining pressure characteristics, the triaxial creep test of sandstone was carried out by TAW-2000 test system. Based on the improved Nishihara model, the model creep parameters are denormalized by introducing the relationship between damage variables and time. The improved variable parameter creep aging model is obtained. The results show that the time-dependent creep model with variable parameters can not only describe the attenuation creep and stable creep deformation characteristics of rocks, but also make up for the shortcomings that traditional creep models cannot describe accelerated creep characteristics. And it predicts the development of creep deformation well. The good agreement between the model and the test curve illustrates the correctness and rationality of the model.

Permanent magnet synchronous motor (PMSM) is a typical nonlinear and multi-variable coupled system, which is sensitive to the uncertainty or variations in the motor parameters and the external disturbance which lead to the deterioration of the steady-state performance. Therefore, it is necessary to introduce effective control methods to improve the drive quality. In this paper, the DQ-axes inductances considering the magnetic saturation of the PMSM which has a significant influence on the operating characteristics are obtained, and the variable parameters are substituted into the control system. Then, a novel sliding mode control strategy is analyzed and adopted. An improved exponential reaching law is proposed in order to solve the chattering problem and improve the performance, which is verified by the theory and simulation. It demonstrates the smooth and quick responses using the new approach can be achieved to enhance the robustness of the drive system compared with conventional sliding mode control method.

The design and development processes of gas turbine engines rely on the usage of mathematical models representing the physics of engine functioning processes. One way of increasing the validity of a mathematical model is its identification based on engine test results. The identification of mathematical models of modern power- generating gas turbine engines (GTEs) presents a demanding and time-consuming task due to the necessity to identify the main controlled engine parameters determined in the course of experimental studies depending on a large number of the parameters that are not controlled during the experiment. In this regard the actual direction of reducing the labour intensity of the process of mathematical model identification is using identification program complexes. The object of the study was to solve the problem of structural-parametrical identification of the power-generating GTE functioning model detailing the turbine flow path calculations to the level of blade rows in order to obtain the GTE mathematical model that describes the characteristics of a real engine with given accuracy. To achieve the objective, the following problems were solved: variable parameters, controlled parameters and characteristics, ranges of their variations were selected from the total number of the mathematical model input data, the objective functions were defined; the task of the parametric identification according to the results of bench tests through GTE operating modes was performed; analytical approximating dependences for correcting coefficients (variable parameters) were obtained; structural-parametric identification of the mathematical model was performed. The novelty of the obtained results is the identification of the mathematical model of the nonlinear component GTE of the second level performed without model linearization (without its level lowering) by using the Optimum software packages. The methodological approach for the parametric identification of the mathematical model is proposed. This approach allows reducing the number of variable parameters under the modes lower that the maximum. It shows that the identified model allows obtaining the prediction results of the GTE parameters and characteristics through operating modes with a deviation of no more than 1.4% from the experimental data and, therefore, it will allow reduction of terms and an increase in the quality of power unit development. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology 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 this paper, the economic-statistical design of the variable parameters (VP) s chart is investigated, where all the design parameters of the s chart are allowed to vary between two values as a function of the most recent process information. The optimal design parameters of the VP s chart are derived based on the economic and statistical criteria. The economic-statistical design is performed by minimizing the cost function with the imposed in-control and out-of-control statistical constraints. The cost of the economic-statistical design is slightly higher than the economic design due to the imposed statistical constraints. The effect of cost and process parameters on the optimal design parameters, statistical performance and minimum expected cost is examined and discussed. The comparison results indicate that the cost of the VP s chart is lower than the variable sample size and sampling interval (VSS) s chart, the variable sampling interval (VSI) s chart, the variable sample size (VSS) s chart and the standard s chart. [ABSTRACT FROM AUTHOR]

The rapid growth of world population in the past few decades requires a respective development of infrastructure, especially in populated coastal regions. This makes the construction on weak soils inevitable. Among many ground improvement approaches, electro-kinetic consolidation (EK) is an innovative method which is also applicable in some extreme conditions such as underwater construction. However, the application of EK in engineering design requires a method for formulation and/or simulation, that can facilitate parametric studies. This paper presents a new numerical model for multi-physics simulation of electrical, hydraulic and mechanic phenomena in EK with variable parameters. Using finite element analysis facilitated by COMSOL MultiPhysics, the model estimates the influence of gravity and electromagnetic field on the pore water flow by several partial differential equations. A comparison of numerical and experimental results shows a good agreement. [ABSTRACT FROM AUTHOR]

The paper studies the existence result for a new class of Kirchhoff elliptic system with variable parameters in the right hand side. Sub-super solutions method are used for proving the main result. Our study is a natural improvement result of our previous one in (Boulaaras et al. in Math. Methods Appl. Sci. 41:5203-5210, 2018). [ABSTRACT FROM AUTHOR]

Evaluating the effect of measurement errors on either adaptive or simultaneous control charts has been a topic of interest for the researchers in the recent years. Nevertheless, the effect of measurement errors on both adaptive and simultaneous monitoring control charts has not been considered yet. In this paper, through extensive numerical studies, we evaluate the effect of measurement errors on an adaptive (variable parameters) simultaneous multivariate control chart for the mean vector and the variance‐covariance matrix of p quality characteristics assumed to follow a multivariate normal distribution. In order to do so, (a) we use eight performance measures computed using a Markov chain model, (b) we consider the effects of multiple measurements as well as the error model's parameters, and (c) we also consider the overall performance of this adaptive simultaneous chart including the chart parameters values optimization, which have never been considered so far for this scheme. At last, a real case is presented in order to illustrate the proposed scheme. [ABSTRACT FROM AUTHOR]

In the machine building industry, the classification and coding of parts, subassemblies and assemblies have a special importance. The relationship between classifications and codifications is defined by the degree of their interdependence or overlap. The main objective of coding, which also determines its basic function, is identification. If it also takes on the meanings of the relations between the elements of the set, it also fulfills the function of representing the classification. In this paper we want to present an innovative coding system for assemblies in the design phase, more precisely the parameterized design. [ABSTRACT FROM AUTHOR]

A high-accuracy numerical method based on a sixth-order combined compact difference scheme and the method of lines approach is proposed for the advection–diffusion transport equation with variable parameters. In this approach, the partial differential equation representing the advection-diffusion equation is converted into many ordinary differential equations. These time-dependent ordinary differential equations are then solved using an explicit fourth order Runge–Kutta method. Three test problems are studied to demonstrate the accuracy of the present methods. Numerical solutions obtained by the proposed method are compared with the analytical solutions and the available numerical solutions given in the literature. In addition to requiring less CPU time, the proposed method produces more accurate and more stable results than the numerical methods given in the literature.

An efficient process monitoring system is important for achieving sustainable manufacturing. The control charting technique is one of the most effective techniques to monitor process quality. In certain processes where the process mean and variance are not independent of one another, the coefficient of variation (CV), which measures the ratio of the standard deviation to the mean, should be monitored. In line with industrial settings, where at least two or more variables are monitored simultaneously in most processes, this paper proposes a variable parameter (VP) chart to monitor the multivariate CV (MCV). Formulae and algorithms to optimize the various performance measures are discussed. The proposed VP MCV chart is designed based on a Markov chain approach. The performance comparison shows that the proposed VP MCV chart prevails over the existing MCV charts, in terms of the average time to signal (ATS), standard deviation of the time of signal (SDTS), and expected average time to signal (EATS) criteria. An example is presented to illustrate the implementation of the proposed VP MCV chart. [ABSTRACT FROM AUTHOR]

A prominent issue in microgrid (MG) cost optimisation is the consideration of variable parameters such as demand, wind speed, sun radiation intensity etc. This study deals with mitigating substantial deviation between study results and actual MG operation indices. The deviation is the result of ignoring the effects of power electronics devices in the optimisation algorithm. A new optimisation model is proposed to involve the main converter's restrictions in the optimisation process. For connecting renewable sources with uncertain outputs such as photovoltaic, wind, and also loads to a MG, using power electronic converters is inevitable. This study proposes an operation cost optimisation development by foreseeing the effects and limitations of power electronic devices, disregarding of which would undoubtedly lead to a notable deviation in optimisation results. [ABSTRACT FROM AUTHOR]

This paper presents an inverse study of heat transfer of a conductive, convective and radiative annular fin made of a functionally graded material. Three major parameters such as conductive–convective parameter, conductive–radiative parameter and the parameter describing the variation of thermal conductivity are inversely estimated from a specified temperature field. The forward solution of temperature field is obtained from the closed form solution of nonlinear heat transfer equation using Homotopy perturbation method (HPM). A dragonfly algorithm that simulates the swarming behaviour of dragonflies, as analogous, is employed in finding out the inverse parameters. The temperature values of the forward solution are used as input data for the inverse analysis. The inverse parameters are then estimated iteratively by minimizing the objective function until the guessed temperature field approximately satisfies the preassigned temperature field of the forward solution. The inverse simulation following HPM-based forward solution converges faster than ordinary differential equation-based forward solution. The reconstructed temperature fields obtained from the various combination of inverse parameters give good agreement (∼1% error) with the desired temperature field. Thus, the presented inverse model provides an opportunity to the fin designer for selecting the several feasible combinations of thermal parameters suggesting the material design that result in a prescribed temperature field. [ABSTRACT FROM AUTHOR]

The paper presents a direct numerical simulation (DNS) for the drag-reducing channel flow using the Giesekus model with variable parameters. It is assumed that the relaxation time in the constitutive equation is varied depending on the local shear rate. The maximal drag reduction rate is obtained when variable parameters are applied in the Giesekus model at a high Weissenberg number. The Reynolds shear stress is reduced when the Weissenberg number increases. In this case, the turbulence generation and transportation are further weakened and increasingly approach to the values in the experiments. [ABSTRACT FROM AUTHOR]

The main purpose of the study is to introduce the multi-objective optimization using Pareto approximations to problems of chemical kinetics. We report the setting up and solution of the multi-objective optimization problem for conditions of a chemical reaction on the basis of a kinetic model. The study addresses the reaction of alcohols with dimethyl carbonate catalyzed by cobalt or tungsten carbonyl. The objective functions for optimization of chemical reaction conditions based on a kinetic model are presented. The NSGA-II algorithm was applied to determine the Pareto set and front for the multi-objective optimization problem applied to the reaction of alcohols with dimethyl carbonate for two catalysts, which make it possible to find the compromise values of variable parameters providing extrema of the objective functions. [ABSTRACT FROM AUTHOR]

Stability problems of the stationary trajectories of the tool elastic deformational displacement under the longitudinal endmilling are considered. In the moving coordinates which displacement is determined by the actuators motion, the stationary steady state is not an equilibrium point (as when turning), but some closed trajectory. The synergetic concept of the analysis of trajectories executed in two stages is used. At the first stage, the established stationary trajectories are calculated according to the offered technique. At the second stage, the stability of these trajectories is analyzed. A case, when the equation parameters in variations under the fixed trajectory can be considered constant within the system impulsive reaction, is considered. Features of the stationary trajectories formation are studied; conditions under which they converge to some steady trajectories are obtained. Besides, some general properties of the loss of balance are received. An example of analysis is cited, and recommendations for ensuring stability of a trajectory of the established form-building motions are given.

One of the 3D printing processes that use polylactide (PLA) wire to generate spatial parts in a large variety of shapes and dimensions is the fused deposition modeling. Due to the action of various factors, the final 3D printed parts obtained employing the fused deposition modeling may present some differences between the desired dimensions and real obtained dimensions. To investigate such an aspect, experimental research involving the use of an L9 array following the Taguchi method principles is designed and achieved. The heights and the diameters of tubular test samples made of polylactide are considered as process output parameters. As process input factors, wall thickness, printing speed, cooling conditions, and plate temperature are used. By mathematical processing of the experimental results, empirical power models type is determined. These models show that the printing speed and plate temperature have the most significant influence on the height and diameter of the 3D printing in the case of tubular parts made of PLA. [ABSTRACT FROM AUTHOR]

In the paper the influence function and the method of partial discretization in free axisymmetric vibration analysis of multilayered circular plates of constant and linearly variable thickness were presented. The effects of shear deformation and rotary inertia for the core as well as the facings were neglected. An analytical investigation based on the classical plate theory was made for the multilayered plate which satisfies Sokołowski’s condition. Discretization of mass and replacing stiffness of a fixed circular plate were presented. Formulas of influence matrix and Bernstein-Kieropian’s estimators for different steps of discretization were defined. The influence of variable distribution of parameters on the value of double estimators of natural basic and higher frequency of a sandwich circular plate was investigated.

In this paper, by transforming the original problem equivalently, we propose a new preconditioned iterative method for solving saddle point problem. We call the new method as PTU (preconditioned transformative Uzawa) method. And we study the convergence of the PTU method under suitable restrictions on the iteration parameters. Moreover, we show the choices of the optimal parameters and the spectrum of the preconditioned matrix deriving from the PTU method. Based on the PTU iterative method, we propose another iterative method – nonlinear inexact PTU method – for solving saddle point problem. We also prove its convergence and study the choices of the optimal parameters. In addition, we present some numerical results to illustrate the behavior of the considered algorithms. [ABSTRACT FROM AUTHOR]

Abstract An unsteady flow model that allows a variable roughness coefficient for each computational point according to its spatial position (x) and the value of discharge (Q) was developed. A step function and a power function were considered for functional relationships between discharge and Manning's roughness coefficient (n). The model was applied to the main reach of the Han River and model parameters were estimated by optimization. From the model calibration, spatial variation and discharge dependence of Manning's n were identified by testing different n (x , Q) functions. First, the value of the roughness coefficient is higher for the upstream reach of the Wangsook Stream junction than it is for the downstream reach. Second, estimated parameters of both the step function model and the power function model show that Manning's n decreases as discharge increases. This tendency is more noticeable for the upstream reach of the Wangsook Stream junction compared to the downstream reach. Further, the stages calculated by the variable roughness coefficient model are more consistent with the observed ones than those from the conventional constant parameter model. Regarding the variation of Manning's n relative to discharge, adopting a power function as the Manning's n -discharge relationship seems to be more appropriate than adopting a step function because it is easy to apply and the performance is as good as that of the step function model. [ABSTRACT FROM AUTHOR]

Abstract: Alpine deciduous shrubs play an important role in local water cycle for ecosystems of Qinghai‐Tibet Plateau, but rainfall partitioning of the deciduous shrubs has not been fully understood due to significant variation in spatial coverage and leaf storage capacity, especially the lack of appropriate model to describe relevant processes. To assess these processes, field experiments were performed to determine vegetation and atmospheric parameters for the deciduous Potentilla fruticosa shrub in the growing season of 2012. Based on the experimental data, a variable parameters Gash model specifically for deciduous shrub rainfall partitioning was adapted from the revised Gash model to simulate rainfall partitioning. Results showed that the interception, throughfall, and stemflow accounted for 21.44%, 29.26%, and 49.30% of total rainfall in the shrub patches, respectively. Nearly half of interception (46.1%) was lost through evaporation from saturated leaf canopy during rainfall events. The performance of the original model on deciduous shrub canopy was improved by utilizing a variable parameters Gash model that adopted event‐based changeable meteorological and canopy parameters. The rainfall partitioning pattern in the shrub patch was very sensitive to changes in canopy coverage, evaporation, and rainfall intensity, in which great varieties can add large potential errors to the revised Gash model simulations. To accurately model rainfall partitioning, it is reasonable to adopt variable parameters. [ABSTRACT FROM AUTHOR]

This research proposes a novel low-voltage inverter-fed motor drive with variable parameters achieved through the independent armature winding for the automobile traction motor. The independent armature winding with low-voltage inverters can improve the total efficiency by reducing the converter losses. The inverters are able to change their connections to different coils groups of the armature winding in order to achieve the wide operating range. The voltage equation of each mode can be shown by using the transformation matrix when the winding connection is changed. Thus, the proposed motor is called the MATRIX motor. In this paper, the downsized model was designed to verify the principle. The principle model is able to achieve four motor parameters. It was confirmed that the principle model could extend the operating range and could achieve the high-efficiency driving in wide speed range. Furthermore, the novel winding reconfiguration method is proposed that not only avoids the surge voltage, but also compensates the torque reduction during the winding reconfigurations. [ABSTRACT FROM AUTHOR]