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In order to strengthen the detection and monitoring of space targets, especially non-cooperative targets, more and more attention has been paid to the characteristics of space targets. The position, velocity, attitude, angular velocity and material complex refractive index of space target were inversely estimated by unscented Kalman filter (UKF). The observation angle, photometric and degree of polarization data were used as the observation values to estimate the state of the target. Based on the position and velocity kinematics model and the attitude and angular velocity dynamic model, the time evolution of the five states was completed, and the joint estimation of the five state parameters was realized. The simulation results show that setting reasonable initial state value, state equation and measurement equation noise, the errors of five state parameters can converge reasonably, and UKF can better predict the five characteristic parameters of space targets. At the same time, it is also verified that the observation angle, luminosity and polarization data can be used to retrieve the five indirect observation characteristic information of space moving targets. [ABSTRACT FROM AUTHOR]

In this paper, the new non-integer-order state space model of heat processes in a one-dimensional metallic rod is addressed. The fractional orders of derivatives along space and time are not exactly known, and they are described by intervals. The proposed model is the interval expanding of the state space fractional model of heat conduction and dissipation in a one-dimensional metallic rod. It is expected to better describe reality because the interval order of each real process is difficult to estimate. Using intervals enables describing the uncertainty. The presented interval model can be applied to the modeling of many real thermal processes in the industry and building. For example, it can describe the thermal conductivity of building walls. The one-dimensional approach can be applied because only the direction from inside to outside is important, and the heat distribution along the remaining directions is uniform. The paper describes the basic properties of the proposed model and supports the theory via simulations in MATLAB R2020b and experiments executed with the use of a real experimental laboratory system equipped with miniature temperature sensors and supervised by PLC and SCADA systems. The main results from the paper point out that the uncertainty of both fractional orders impacts the crucial properties of the model. The uncertainty of the derivative along the time affects only the dynamics, but the disturbance of the derivative along the length disturbs both the static and dynamic properties of the model. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute 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.)

It is noted that, in the general case, diagrams of cyclic elastoplastic deformation of a material characterize its resistance to low-cycle loading and display the relationship between current stress values and deformation during deformation. Such diagrams in the mechanics of deformation and fracture are described by complex equations of state that depend nonlinearly on the conditions and loading modes, including temperatures, strain rates, cycle shapes, types of stress state, absolute dimensions of sections, types of working media, types of structural material, etc. The mentioned factors in their entire complex influence the shape of curves (diagrams) of material deformation and the main parameters of the equations of state describing them, for example, such basic characteristics of mechanical properties as the modulus of elasticity, yield stress and ultimate strength, and indicators of static and cyclic hardening. As exemplified by experimentally obtained data on the kinetics of cyclic and one-sided accumulated plastic deformations in each of the half-cycles (cycles) of loading during static and low-cycle tests of specimens from a heat-resistant nickel alloy, it is shown that, under conditions of cyclic elastoplastic deformation, these deformation characteristics have an essentially nonlinear pattern of change, which is described on the basis of power equations and the parameters of cyclic deformation diagrams included in them. Here, the parameters of these equations depend on the type of cyclically hardening, softening, or stable material during its deformation in the elastoplastic region. It is noted that the resistance to cyclic elastoplastic deformations of a material can be described by a set of analytical expressions with a kinetic function included in them, which varies over the number of loading half cycles, in the form of power or exponential expressions depending on the cyclic properties of the material and data on the characteristics of the mechanical properties of specific structural materials. The obtained computational and experimental data on the kinetics of deformations of the alloy under study during its cyclic elastoplastic loading and on the parameters of the deformation diagrams, which are the basic characteristics for the corresponding equations of state, make it possible to fully apply the deformation-kinetic criterion for the accumulation of damage under the considered loading conditions for calculating the durability of structural elements made from it, which are operated, as a rule, under complex temperature and power conditions. The results of the performed experiments and calculations are presented in the form of diagrams of the cycle-by-cycle kinetics of cyclic and accumulated plastic deformations of the studied material under soft and hard loading conditions and in a wide range of test temperatures. [ABSTRACT FROM AUTHOR]

In this paper, the new non-integer-order state space model of heat processes in a one-dimensional metallic rod is addressed. The fractional orders of derivatives along space and time are not exactly known, and they are described by intervals. The proposed model is the interval expanding of the state space fractional model of heat conduction and dissipation in a one-dimensional metallic rod. It is expected to better describe reality because the interval order of each real process is difficult to estimate. Using intervals enables describing the uncertainty. The presented interval model can be applied to the modeling of many real thermal processes in the industry and building. For example, it can describe the thermal conductivity of building walls. The one-dimensional approach can be applied because only the direction from inside to outside is important, and the heat distribution along the remaining directions is uniform. The paper describes the basic properties of the proposed model and supports the theory via simulations in MATLAB R2020b and experiments executed with the use of a real experimental laboratory system equipped with miniature temperature sensors and supervised by PLC and SCADA systems. The main results from the paper point out that the uncertainty of both fractional orders impacts the crucial properties of the model. The uncertainty of the derivative along the time affects only the dynamics, but the disturbance of the derivative along the length disturbs both the static and dynamic properties of the model.

Structural vibration includes both translational and rotational degrees of freedom, but the latter are often ignored. The paper establishes a dynamic inclination measurement model based on the existing accelerometer, and constructs state and measurement equations that comprehensively represent translational and rotational degrees of freedom. Then, the extended Kalman filtering method is used to linearize and discretize the state equation and measurement equation, and the filtering process of dynamic Inclination Identification is derived. The feasibility of the method was verified through an example of a simply supported beam structure. [ABSTRACT FROM AUTHOR]

Smart transformation and green development are the core research directions of electric vehicles. An electric tractor is powered by the vehicle battery. The motor converts electric energy into mechanical energy and drives the wheels through the drive train. Therefore, the electric tractor model is a modular mathematical model for the battery, motor, drive train, and drive wheel. A class of high-order terminal sliding mode control strategies is adopted to establish the relative rotational angles of drive wheels, driving angular speeds, and motor angular speeds as input, and driving angular speeds and motor angular speeds as output. This process ensures stable operating speed and good working quality under the operating conditions and achieves small-scale unattended driving. The output is a nonlinear system state equation. An n-order derivative continuous function is introduced to design the terminal sliding surface of the sliding mode. A control function to reduce chattering is also designed to ensure that the output function converges at the finite time and the existing sliding stage achieves zero steady-state error. Simulation results of the whole electric tractor model show that the speed remains stable under the condition of outside interference, and experiments verify the feasibility of the control strategy. [ABSTRACT FROM AUTHOR]

For a hydropower system with a relatively short tail tunnel and wide variation of tail water level, the ceiling-sloping tail tunnel (CSTT) is often recommended. Considering various flow patterns and traveling free-surface-pressurized interface in the CSTT, stability modeling and analysis of the governor-turbine-hydraulic system shows more challenging. Based on state equations analysis, an improved nonlinear model considering transition part, and a new linear model for downstream free-surface flow are derived. Further comparative analysis indicates that, by introducing these models, water flow characteristics in transition part have positive effect on operation stability with an around 4.0% increase of attenuation rate, while that of downstream free-surface flow has a negative effect with a 21.8% decrease rate on the absolute value of negative attenuation factor. For stability optimization of the CSTT, to properly increase its bottom width is preferable, herein with a 6.2% increase of attenuation rate for a 2.0 m increase of bottom width, while a reasonable ceiling slope should be optimized considering the counteraction effect of upstream pressurized flow and downstream free-surface flow. The new developed models and further discussion for the hydropower systems with a CSTT will greatly improve system's stability evaluation and advance the development of renewable energy. • A new nonlinear model considering the effect of flow transition part is developed. • A linear stability model for the downstream free-surface flow is derived. • Positive effect of water flow in transition part on operation stability is revealed. • Negative effect of downstream free-surface flow on operation stability is clarified. • Optimization criterion of the ceiling-sloping tail tunnel is presented. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION 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.)

Copyright of Special Oil & Gas Reservoirs is the property of Special Oil & Gas Reservoirs 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.)

Petri nets (PNs) can model various event-driven systems well and detect a fault via reachability analysis. Some state-equation-based approaches are designed for only subclasses of PNs with specific structures. A key issue for PNs’ reachability analysis approach based on state equation is that a non-negative integer solution (NIS) to a state equation is necessary but not sufficient for a marking’s reachability. In this paper, we propose a circuit-based subnet. For ordinary Petri nets with token-free circuit-based subnets, we present an algorithm to determine that the state equation has NISs but the marking is non-reachable. We adopt a divide-and-conquer strategy to consider each circuit-based subnet. The proposed method is tested on a PN-based flexible manufacturing system with unreliable resources. When unreliable resources are lost, the non-reachable markings can be determined effectively. Besides, simulations are done, and the results verify the efficiency of the proposed algorithm compared with the reachability-tree-based method.

Following a recently considered generalisation of linear equations to unordereddata vectors and to ordered-data vectors, we perform a further generalisation to data vectors that are functions from k-element subsets of the unordered-data set to vectors of integer numbers. These generalised equations naturally appear in the analysis of vector addition systems (or Petri nets) extended so that each token carries a set of unordered data. We show that nonnegative-integer solvability of linear equations is in nondeterministic exponential time while integer solvability is in polynomial time. [ABSTRACT FROM AUTHOR]

The nonlinear state equations describing the coupling between control rod drop and fluid flow were proposed to solve the problem of control rod drop in nuclear reactors. The state equations have a uniform format for different fluid states in the process of control rod drop, which can conveniently deal with the problem for different working conditions. To efficiently analyze the falling process, accurately capture the sudden change of flow state and ensure the numerical stability of time integral, an adaptive time step-based symplecticity-preserving algorithm was proposed. Numerical examples show that, the proposed numerical model can accurately calculate the key data such as the displacement, the velocity, the acceleration and the falling time of the control rod in the falling process with a large time step, and the calculated results are in good agreement with those obtained the by the commercial software. [ABSTRACT FROM AUTHOR]

Abstract In this work, we have determined the mean square relative displacement, elastic constant, anharmonic effective potential, correlated function, local force constant, and other thermodynamic parameters of diamond-type structured crystals under high-pressure up to 14 GPa. The parameters are calculated through theoretical interatomic Morse potential parameters, by using the sublimation energy, the compressibility, and the lattice constant in the expanded X-ray absorption fine structure spectrum. Numerical results agree well with the experimental values and other theories.

A common type of scheduling policy includes first-in-first-out (FIFO) and earliest-outset bases. Among many approaches to this, max-plus linear representation is beneficial for event-driven discrete event systems (DESs). The earliest event occurrence times can be represented by linear relations in max-plus algebra, the resultant of which is analogous with the state equation in modern control theory. Methodologies in control theory such as evolution prediction and just-in-time scheduling can thus be utilized. Although useful, the description capability remains confined to FIFO contexts, for which the method would not be capable of producing an efficient solution for systems with two-level priorities. An entity, e.g. a task or token in scheduling contexts, with higher qualification would be prioritized over one with a lower qualification. A framework for overtaking tasks is necessary for this. Motivated by this need, this article is concerned with constructing a two-level priority scheduling methodology in a max-plus linear context. A numerical experiment applied to a simple manufacturing system highlights the significance of the constructed method.

Smart transformation and green development are the core research directions of electric vehicles. An electric tractor is powered by the vehicle battery. The motor converts electric energy into mechanical energy and drives the wheels through the drive train. Therefore, the electric tractor model is a modular mathematical model for the battery, motor, drive train, and drive wheel. A class of high-order terminal sliding mode control strategies is adopted to establish the relative rotational angles of drive wheels, driving angular speeds, and motor angular speeds as input, and driving angular speeds and motor angular speeds as output. This process ensures stable operating speed and good working quality under the operating conditions and achieves small-scale unattended driving. The output is a nonlinear system state equation. An n-order derivative continuous function is introduced to design the terminal sliding surface of the sliding mode. A control function to reduce chattering is also designed to ensure that the output function converges at the finite time and the existing sliding stage achieves zero steady-state error. Simulation results of the whole electric tractor model show that the speed remains stable under the condition of outside interference, and experiments verify the feasibility of the control strategy.

This paper summarizes a bibliographic review of the main articles published in recent years in the power cycles area, with special emphasis on working fluid mixtures. Likewise, the most relevant theoretical fundaments for performing the mathematical modeling of this class of working fluids and, therefore, obtaining their thermodynamic properties, as well as the experimental methods used in the characterization of the phase equilibrium that allow obtaining the adjustment parameters are covered in this article.

In order to efficiently recover and utilize the produced fluid from high-CO2 gas wells in Huangqiao, thermodynamic state equation (PRSV state equation and WS mixing rule) and flash evaporation calculation theory were adopted for phase state calculation of the produced fluid from high-CO2 gas wells in Huangqiao, which revealed the phase diagram feature of the high-CO2 well flow in Huangqiao and the influence of CO2 on the phase state of oil and gas hydrocarbon system. Specifically, the gas-liquid two-phase area, which is on the p-T phase diagram of oil and gas hydrocarbon system containing CO2, decreases significantly with the increase of CO2 mole fraction. According to the phase characteristics of the produced fluid, the surface treatment process of single well was established, and the operating parameters of key equipment (cyclone separator and CO2 compressor) in the produced fluid treatment process were analyzed, concluding that all the currently selected operating parameters were in the reliable working area (single phase gas area) of cyclone separator. There was no liquid phase precipitation in the full working pressure and temperature range of CO2 compressor. The established gathering and transportation process flow and operating parameters of equipment in Huangqiao high-CO2 single wells have been verified to be reasonable, and on this basis, free water and liquid crude oil can be effectively removed from the high-CO2 single well flow in this area. The process flow and operating parameters of equipment can be promoted and used in similar condition blocks of this area.

Copyright of Natural Gas & Oil is the property of Editorial Department of Natural Gas & Oil 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.)

The bond graph (BG) method is an appropriate tool to model hybrid systems. The automated extraction of state equations from BG is the main drawback of this method. In this paper, a new method has been presented to simply extract the state equations from BG (SEBG method). Initially, SEBG has converted the BG model to the bond-element table (BE-table) to gain all the information of BG in a systematic representation. It has then formed a set of algebraic equations using elements' functions (E-functions) and found the power variables by solving them. Finally, the system's state equations are established using BE table, power variables, state vector, and states' functions, based on the fact that only the relations of inertial and capacity elements contain the first-order differential equations. Moreover, the simplicity and practicality of SEBG have been examined for finding the state equations of two systems. [ABSTRACT FROM AUTHOR]

Concrete slabs are typically subjected to impact loading, and the selection of the equations of state and failure criteria has significant effects on the dynamic mechanical behavior of concrete. One of the most commonly adopted impact loading is projectile impact. In this study, the optimization analysis of the equation of state and failure criterion for rigid projectile penetration, which are often available for theoretical models, were analyzed using regression evaluation methods. Subsequently, based on the analysis results, a multi-phase model for the penetration of rigid projectiles into concrete was established which combined with the dynamic cavity expansion theory. Finally, the prediction results of the proposed model were compared with existing experimental data and prediction results of existing penetration models. The results showed that the prediction model has a wide range of applicability and high accuracy. • A multi-stage penetration model for predicting the damage behavior of concrete is proposed. • Analysis and assessment of models using regression evaluation methods. • The results show that the model is better than the commonly used penetration model. • The prediction model results have a wide range of applicability and high accuracy. [ABSTRACT FROM AUTHOR]

In this work we present new analytical (i.e., without computer modeling) method for calculating the dependence of the nanocrystal melting temperature both on pressure and on the size (number of atoms N) and surface shape of the nanocrystal. This method is based on the paired Mie – Lennard-Jones interatomic interaction potential, and takes into account the dependence of both the state equation and other lattice properties on the size and shape of the nanocrystal. For the first time, the dependences of the melting temperature on the pressure P , size N , and shape f of the nanocrystal were obtained. Calculations have been performed for gold, platinum and iron. It is shown that at any pressure, the melting point T m (P , N , f) decreases both with an isomorphic-isobaric (f , P – const) decrease in the number of N atoms, and with an isomeric-isobaric (N , P – const) deviation of the nanocrystal shape from the energy-optimal shape. It is shown that the value of the baric derivative of the melting temperature T m ′(P) for a nanocrystal at low pressures is greater, and at high pressures less than the T m ′(P) value for a macrocrystal. At this, the dependence of the T m ′(P) function on the nanocrystal size is insignificant, i.e., at constant N-f -arguments, the baric dependences T m (P , ∞) and T m (P , N , f) are practically parallel. It is indicated how this method can be applied for experimental evaluation of the pressure under which a nanocrystal is located in a refractory matrix. • Method for calculate T m (P) dependence on size and nanocrystal shape was developed. • The T m (P) dependences were calculated for cub and rod Au nanocrystal of 306 atoms. • The T m (P) decreases inatoms number decrease, or inshape deviationofoptimal ones. • Baric derivative of T m (P) for nano at low P big and at high P less than for macro. • Method can evaluate of P under which a nanocrystal located in a refractory matrix. [ABSTRACT FROM AUTHOR]

State equations are usually used for structural or qualitative analysis, such as deadlock checking, in P/T systems. In this paper, we instead consider timed state equations in stochastic process algebra models, to derive quantified dynamic information on the system modeled in the face of the state space explosion problem. The average of these state equations is demonstrated as the linear combination of the system transitions, with the combination coefficients specified by the bias term of the empirical transition rates to their steady state. The approaches of stochastic simulation and fluid approximation, straightforwardly generated from the quantified state equations, are studied, with the consistency being investigated both theoretically and experimentally.

This paper presents a new supercritical carbon dioxide (SCO2) cannon based on the carbon dioxide (CO2)'s thermodynamic cycle under constant volume. First, Virial equation and NIST database are applied to formulate SCO2's property and analyze the thermodynamic cycle, which is aimed to get the optimization equation using the cannon's exit velocity as objective function. Then the cannon's structural parameters, such as diaphragm thickness and barrel length, and CO2's filling mass, are optimized. Finally, the flow field and velocity's change during the launch process is performed with FLUENT. In field test, the ultra-high pressure sensor and ultra-high speed camera are used to measure the pressure distribution along the barrel's axial direction and the projectile's exit velocity under different conditions. The results show that all the performance indexes meet the design requirement. The innovative SCO2 cannon in this paper has obvious advantages such as high safety, low cost and fast loading, which can be applied in many situations such as disaster relief, peacekeeping and anti-terrorism. Moreover, the unique energy storage method and thermodynamic design ensure its subsequent development. [ABSTRACT FROM AUTHOR]

In this paper, exact solutions with a linear velocity field are sought for the gas dynamics equations in the case of the special state equation and the state equation of a monatomic gas. These state equations extend the transformation group admitted by the system to 12 and 14 parameters, respectively. Invariant submodels of rank one are constructed from two three-dimensional subalgebras of the corresponding Lie algebras, and exact solutions with a linear velocity field with inhomogeneous deformation are obtained. On the one hand of the special state equation, the submodel describes an isochoric vortex motion of particles, isobaric along each world line and restricted by a moving plane. The motions of particles occur along parabolas and along rays in parallel planes. The spherical volume of particles turns into an ellipsoid at finite moments of time, and as time tends to infinity, the particles end up on an infinite strip of finite width. On the other hand of the state equation of a monatomic gas, the submodel describes vortex compaction to the origin and the subsequent expansion of gas particles in half-spaces. The motion of any allocated volume of gas retains a spherical shape. It is shown that for any positive moment of time, it is possible to choose the radius of a spherical volume such that the characteristic conoid beginning from its center never reaches particles outside this volume. As a result of the generalization of the solutions with a linear velocity field, exact solutions of a wider class are obtained without conditions of invariance of density and pressure with respect to the selected three-dimensional subalgebras.

The state space method has been widely used to analyze the static and dynamic characteristics of homogeneous, laminated, functionally graded, or even intelligent structures. However, the solution of the state equation using the traditional transfer matrix generally encounters the problem of numerical instability. This work, therefore, derives the general solution to the state equation by making use of similarity transformation to convert the system matrix into a matrix in Jordan canonical form (including the diagonal matrix as a special case), so as to avoid the previously stated problem. A special form of the exponential function is also introduced according to the characteristics of the eigenvalues of the system matrix. Furthermore, the undetermined coefficients in the general solution—rather than the original state variables—are considered as the primary unknowns. Consequently, a new solution with numerical robustness to the state equation is obtained. Finally, numerical examples for the free vibration analyses of beams and plates as well as interfacial shear stress analysis of fiber-reinforced polymer (FRP)-strengthened concrete beams are presented to verify that the proposed procedure can circumvent numerical instability completely. [ABSTRACT FROM AUTHOR]

An approach to the problem of solution prediction on the basis of the mathematical model of cognitive digital automata (CDA) is proposed. A particular advantage of the proposed mathematical model of CDA is that the training procedure can be performed on a limited (minimal) number of training sets. Prediction or generation of solutions, in its turn, is performed on the basis of the mathematical model of CDA obtained in the process of training. The mathematical model of CDA was tested on an example of modeling an n -bit adder. As a result of training, the mathematical model of CDA was formed, which made it possible to reproduce the entire set of the truth table of the n -bit parallel adder with a specified accuracy. [ABSTRACT FROM AUTHOR]

• New insights about RR 141 adsorption were presented considering non ideality. • The intermolecular interactions between the RR 141 molecules cannot be neglected; • OH and COOH groups were more important than aromatic rings for dye adsorption. • The attraction energy between adsorbed molecules cannot be neglected; • The Van der Waals parameter, b , ranged from 0.00001 to 0.00302 L mg−1. In this communication, statistical physics models (sta–phy) coupled with the Van der Waals (VDW) state equation were employed to demonstrate insights regarding the reactive red 141 (RR 141) adsorption onto multi–walled carbon nanotubes (MWCNTs). Experimental isotherms were constructed for two types of carbon nanotubes (MWCNTs–OH and MWCNTs–COOH) at four different temperatures (298, 308, 318 and 328 K). These curves were predicted by sta–phy models coupled or not with the VDW state equation. It was demonstrated that the sta–phy coupled with VDW equation was able to predict the experimental isotherms more accurately than the other used models. Based in this approach, insights about RR 141 adsorption on the MWCNTs were presented considering the following parameters: number of molecules adsorbed at first and second site (n 1 and n 2), density of first and second receptor site (N m 1 and N m 2), concentration at half saturation relative to the first and second receptor site (W 1 and W 2) and VDW interaction parameters (a and b). The Van der Waals parameter related with the co–volume of the adsorbate molecule (b) was significant and ranged from 0.00001 to 0.00302 L mg−1. [ABSTRACT FROM AUTHOR]

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu 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.)

The goal of this work is to generalize second order mathematical models for automotive flow using algorithm for building state equation - the dependency of pressure on traffic density - which is adequate with regard to real world data. The form of state equation, which closes the system of model equations, is obtained from experimental form of fundamental diagram - the dependency of traffic flow intensity on its density, and completely defines all properties of any phenomenological model. The proposed approach was verified using numerical experiments on typical traffic data, obtained from PeMS system (http://pems.dot.ca.gov/), using segment of I-507 highway in California, USA as model system.

Analysis of Pickett’s model of the HP TiO2 memristor presented in this paper reveals an ambiguity of its port equation, which may cause non-convergence, numerical errors, and non-physical solutions during time-domain simulation. As there is no easy fix of the original model a new behavioral approximation of static I-V characteristics has been proposed. The approximation matches well the original model and is unambiguous.