Instantaneous Loss Research Articles

Comparison of Sequence of Physical Processes (SPP) and Fourier Transform Coupled with Chebyshev Polynomials (FTC) methods to Interpret Large Amplitude Oscillatory Shear (LAOS) Response of Viscoelastic Doughs and Viscous Pectin Solution

Fourier Transform coupled with Chebyshev Polynomials (FTC) and Sequence of Physical Processes (SPP) are used to study and interpret the large amplitude oscillatory shear (LAOS) responses of doughs. The doughs were prepared with semolina, hard, soft wheat flours, and a pectin solution was studied as a highly viscous reference. The FTC method enables the extraction of user-friendly measures at limiting conditions (γ→0, γ→ γmax) including (GL′,GM′,GL″,GM″). The SPP method provides instantaneous storage (Gt′) and loss (Gt″) moduli, results in a complete deformation history throughout the oscillation cycle. Rheological characteristics obtained using SPP measures offer a better correlation with protein content, LMW/HMW ratio, and glutenin/gliadin ratio of the flour doughs. Instantaneous moduli (Gt′,Gt″) determined by the SPP method are more sensitive to structural changes than FTC measures for detecting network rupture at lower strain amplitudes. The FTC results show that the nonlinear behavior of dough is characterized by intracycle strain-hardening (GL′ >GM′) and intracycle shear-thinning (GL″ <GM″). The SPP method shows that the doughs undergo a 3-step gradual sequence of physical processes governed by starch/gluten interactions. These steps include: (1) weak strain-hardening and strong-shear thickening due to the elongation of the gluten network and formation of starch hydro-clusters, (2) strong strain-softening, and shear-thickening behavior caused by the relaxation of the gluten network and sustained formation of starch hydro-clusters, (3) weak strain-hardening and strong shear-thinning due to reassembly of the gluten network and the degradation of starch hydro-clusters. Although the FTC method provides user-friendly and easy-to-interpret measures, the time-related information extracted by the SPP method provides a more detailed history of microstructural changes during an oscillation cycle.

Time‐averaged and instantaneous magnetic loss characteristics of different products of electrical steel for frequencies of 16 2/3 Hz up to 500 Hz

Traditionally, products of electrical SiFe steel are focussed on applications for frequencies of 50–Hz. However, the recent developments of electric drive systems yielded a strong extension of the range from f = 16 2/3 Hz up to ca. 500 Hz. In spite of high industrial relevance, the literature offers the corresponding data on the material’s magnetic energy losses in very rare ways. This paper reports a first comparative, multi-parametric study on eight different steel products that comprise non-oriented steels (NO), grain-oriented steels (GO) and scribed grain-oriented steels (SGO). Consistently at IEC-standardized samples, they were analysed for the whole frequency range that was split into low frequency (LF) and medium frequency (MF), with 80 Hz as the border. Data is presented on time-averaged total losses P, on the corresponding hysteresis losses PH and eddy current losses PE. LF proved to be governed by PH and MF rather by PE, however, with strong variations. Further, instantaneous magnetization power functions p(φ) were determined for basic insights into the involved temporal developments of energy dissipation. GO-steels yielded profiles close to rectified co-sinus functions that can be fully attributed to dissipative losses. On the other hand, p(t) of NO-steels and SGO-steels prove to include negative segments that reflect potential energy power, in the course of alignments of atomic moments in instants of high induction. Examples of industrial relevance of the accumulated data are steel production technology, product categorization, failure tracing and energy conversion.

Reactor scale modeling of quorum sensing induced biofilm dispersal

We present a simple reactor-scale mathematical model of active biofilm dispersal that is controlled by a quorum sensing system. The model is cast as a system of three ordinary differential equations for the dependent variables biofilm thickness, quorum sensing signal concentration in the reactor, and concentration of the growth limiting substrate in the reactor. The model is investigated with analytical and numerical techniques. We find that a single QS dispersal mechanism, depending on parameters, can lead to (i) continuous cell loss at a signal level at which the biofilm is entirely up-regulated, (ii) periodically repeating almost instantaneous cell loss with the biofilm switching between down- and up-regulated states, (iii) continuous cell loss at a signal level at which the biofilm is entirely down-regulated, or (iv) complete washout. We contrast this with a simple model of starvation induced dispersal, which is cast in the same modeling framework, but shows entirely different dynamic behavior, in that it only permits washout or asymptotic convergence to a steady state at break-even concentration, depending on parameters.

Evolution mechanism of dynamic thermal parameters of shale

In situ conversion is a process that converts organic matter into light oil and gas via underground in situ heating, which leads to changes in shale material composition and dynamic changes in thermal field parameters. At present, there is a lack of understanding of the evolution behavior and mechanism associated with dynamic thermal field parameters of shale. The dynamic thermal field parameters of shale with different organic matter abundances at various temperatures, orientation, heating rates, and pressures are obtained using an improved surface thermal source method and the laser flash method. The results show that the changes in dynamic thermal field parameters of shale are mainly controlled by organic matter abundance. The thermal diffusivity of shale decreases with the increase in temperature, and the thermal conductivity presents an “M-shaped” dynamic evolution with temperature. The thermal conductivity and thermal diffusivity of shale parallel to bedding are higher than those shale that are perpendicular to bedding. The rapid heating rate decreases thermal diffusivity above 200 °C, which is believed to be due to the instantaneous weight loss rate at high temperatures. The thermal conductivity and thermal diffusivity of shale parallel and perpendicular to bedding show the following two-stage evolution characteristics with the increase in pressure. Through matrix analysis, the bi-directional thermal conductivity model of shale with different organic matter abundances under different temperature and pressure conditions is constructed, which provides accurate parameters for studying dynamic thermal field evolution and efficient heat transfer during in situ conversion.

Comparison of RANS and LES for a cross-flow turbine in confined and unconfined flow

This work examines the dynamic stall process and resulting wake features of cross-flow turbines under confined configurations using two computational modeling approaches, Reynolds-averaged Navier-Stokes (RANS) and large-eddy simulation (LES). Cross-flow turbines harvest energy from wind or water currents via rotation about an axis perpendicular to the flow and are a complementary technology to the more common axial-flow turbine. During their 360° rotation cross-flow turbine blades experience a cyclical variation in the angle of attack and velocity relative to the oncoming flow, leading to flow separation and reattachment, otherwise known as dynamic stall. The dynamic stall process causes an instantaneous loss in torque generation and unsteady force fluctuations which pose a challenge to accurate predictions of both the performance and the resulting unsteady flow field. This research compares RANS simulations to higher fidelity LES of a straight-bladed two-blade cross-flow turbine at a moderate Reynolds number (Rec = 45,000) in a confined configuration. The RANS model is shown to be very sensitive to confinement at the simulated tip speed ratio as it over-predicts power generation due to suppression of flow separation, while the flow field from LES matches well with the experimental validation. Results are compared with an unconfined configuration for which the RANS model successfully predicts a power curve; however, it displays significant differences in the evolution of flow structures such as premature shedding of the dynamic stall vortex and a lack of vortex diffusion during convection in the wake.

Direct Radiative Effects in Haboobs

AbstractConvective dust storms, or haboobs, form when strong surface winds loft loose soils in convective storm outflow boundaries. Haboobs are a public safety hazard and can cause a near instantaneous loss of visibility, inimical air quality, and contribute significantly to regional dust and radiation budgets. Nevertheless, reliable predictions of convective dust events are inhibited by a lack of understanding regarding the complex and non‐linear interactions between density currents, or convective cold pools, and dust radiative effects. In this study, the Weather Research and Forecasting model coupled with Chemistry (WRF‐Chem) is utilized to simulate the effect dust radiation interactions have on a long‐lived haboob case study that spans three distinct radiative regimes: day (high shortwave), evening (low shortwave), and night [longwave (LW) only]. A sophisticated algorithm is used to track and identify the numerous convective old pool boundaries in the simulations and assemble statistics that represent the impact of dust radiative effects. To first order, dust scattering of shortwave radiation in the day leads to a colder, dustier, and faster moving convective cold pool. In the transition period of early evening, the shortwave effects diminish while LW dust absorption leads to warmer, slower density currents that loft less dust as they propagate. At night, the haboob is again warmer due to dust absorption, but gustier in the more stable nocturnal surface layer, leading to enhanced dust emissions.

Robustness of multistory corner‐supported modular steel frames against progressive collapse

SummaryIn current practice, a relatively wide range of different interconnections and assembly systems is being used for the design of modular buildings made of volumetric prefabricated frames. The integration strategies and design criteria for providing structural robustness or prevention of disproportionate collapse for such buildings are completely different with those with conventional systems. This is mainly because of their fundamentally different configuration of joints and the redundancy they provide for the structure. This paper studies the robustness of multistory modular structures, made of prefabricated volumetric steel frames, against progressive collapse, which can be triggered by various column or module loss scenarios. In this study, the flexibility of modules and propagation of the damage inside the individual modules are taken into account, and the buckling of columns, as well as the effects of material nonlinearity on the responses and capacity of the entire system, are also considered. Load redistribution patterns and possible gravity‐induced collapse mechanisms are inspected in various collapse scenarios for a typical mid‐rise modular steel frame. In the numerical model, each individual prefabricated volumetric module is composed of discrete beam and column frame elements, connected through conventional rigid beam–column connections. The volumetric modular steel frames are connected via corner vertical and horizontal intermodule joints; each one is modeled utilizing one axial and two shear springs with predefined nonlinear force–displacement behavior in a 3D finite element analysis. The local damage scenarios are assumed to be due to instantaneous loss of columns or entire modules, for which the interactions between the modular units, overall structural robustness, load redistribution, possible collapse mechanisms, and progressive collapse response of the frames are investigated. The results indicate that the additional redundancy may help the modular steel frames survive from some corner column or single module removals but will not be able to maintain their robustness under combined module removal scenarios.

A detailed account of calculation of shading and blocking factor of a heliostat field

The shading and blocking factor plays a significant role in the design of a heliostat field. It is the most computationally expensive task during the optimization process of a heliostat field. Over time, different methods have been developed to calculate the extent of the optical losses associated with shading and blocking. This paper focuses on the famous center point projection method and its implementation using Matlab. This work provides detailed procedures from the perspective of programming and simulation of central receiver systems. The underlying assumptions, the algorithm's strengths, and weaknesses are highlighted. The procedure and simulation parameters will help in developing optimization algorithms for designing high-efficiency heliostat fields. A dense radial staggered heliostat field is used for testing the performance of the algorithm. The field efficiency is calculated at different design points. The results show that the shading loss of the field changes with time, whereas there is negligible variation in the blocking loss. The instantaneous shading loss of a dense radial staggered field on December 21, noontime is 2.12%, whereas the blocking loss is 1.52%.

A decoupling approach for time-dependent robust optimization with application to power semiconductor devices

In this paper, a time-dependent robust optimization model is proposed by introducing a concept of expected interval quality loss as the robustness metric. The purpose is to provide a potential analysis tool for power semiconductor devices involving stochastic processes. Unlike conventional robustness indicators, the metric is formulated by calculating the expectation and variation of the maximal instantaneous quality loss and capturing the auto-correlation of the quality loss over the time interval. In terms of model solving, the time-dependent robust optimization involves a nested optimization, namely the outer design optimization requires to call the inner robustness analysis frequently. It will lead to extremely low computational efficiency. For reducing robustness evaluations, a decoupling framework is proposed to convert the nested optimization into a sequential iterative process of design optimization and time-dependent robustness analysis. For further improving the efficiency of each robustness analysis, a semi-second-order approximation of quality characteristics is created based on the information at the previous iteration. Two engineering applications of power semiconductor devices verify the validity and feasibility of the proposed approach.

Observations and Simulations of Dropout Events and Flux Decays in October 2013: Comparing MEO Equatorial With LEO Polar Orbit

AbstractWe compare ESA PROBA‐V observations of electron flux at LEO with those from the NASA Van Allen Probes mostly at MEO for October 2013. Dropouts are visible at all energy during four storms from both satellites. Equatorially trapped electron fluxes are higher than at LEO by 102 (&lt;1 MeV) to 105 (&gt;2.5 MeV). We observe a quite isotropic structure of the outer belt during quiet times, contrary to the inner belt, and pitch angle dependence of high energy injection. We find a very good overlap of the outer belt at MEO and LEO at ∼0.5 MeV. We use test‐particle simulations of the energetic electrons trapped in the terrestrial magnetic field to study the outer radiation belt electron flux changes during geomagnetic storms. We show that the Dst (Disturbance storm time) effect during the main phase of a geomagnetic storm results in a betatron mechanism causing outward radial drift and a deceleration of the electrons. This outward drift motion is energy independent, pitch angle‐dependent, and represents a significant distance (∼1 L‐shell at L = 5 for moderate storms). At fixed L‐shell, this causes a decay of the LEO precipitating flux (adiabatic outward motion), followed by a return to the normal state (adiabatic inward motion) during main and recovery phases. Dst effect, associated with magnetopause shadowing and radial diffusion can explain the main characteristics of outer radiation belt electron dropouts in October 2013. We also use Fokker‐Planck simulations with event‐driven diffusion coefficients at high temporal resolution, to distinguish instantaneous loss from the gradual scattering that depopulates the slot region and the outer belt after storms. Simulations reproduce the slot formation and the gradual loss in the outer belt. The typical energy dependence of these losses leads to the absence of scattering for relativistic and ultra‐relativistic electrons in the outer belt, oppositely to dropouts.

Monitoring Real-Time Status of Analog Sources: A Cross-Layer Approach

Real-time status updating or monitoring plays a critical role in emerging applications including Industrial Internet of Things (IIoT) and Vehicular-to-Everything (V2X) systems. In these applications, the real-time status is mostly characterized by analog signal samples desiring lossy compression before digital transmissions. However, how to ensure the data freshness while reducing the distortion due to lossy compression still remains open. In this paper, we are interested in a cross-layer framework aiming at achieving low Age-of-Information (AoI) and compression distortion concurrently in real-time monitoring over fading channels. More specifically, a cross-layer optimization is formulated to jointly control the lossy compression in the application layer and data transmission in the physical layer. We present a hierarchical solution method by decomposing the cross-layer optimization into inner and outer problems. The objective of the inner problem, solved by convex optimization, is to minimize an age-weighted distortion function and strike the optimal tradeoff between the instantaneous AoI and compression loss. The objective of the outer problem, solved by dimension-reduced Constrained Markov Decision Process (CMDP), is to acquire the optimal scheduling policy reducing the average AoI and distortion. We demonstrate the structural results of the optimal cross-layer design, which substantially reduces the protocol complexity in practice.

Ammonia volatilization from urea in alfalfa field with different nitrogen application rates, methods and timing

Ammonia (NH3) volatilization from agricultural activities contributes to climate change and nitrogen (N) loss. Nitrogen management method has an important effect on NH3 volatilization. The purpose of this study was to evaluate the influence of N application rate, method and timing on NH3 loss from alfalfa field. In 2017 and 2018, NH3 volatilization was measured by the calibrated Dräger-Tube method under banding, surface broadcasting and center-pivot fertigation methods with three N application rates (27.6, 48.3, 69.0 kg N ha−1 for each alfalfa cutting). Different application timing (7:00, 12:00, 17:00) was applied for sprinkler fertigation in 2017. The results showed that with irrigation method of center pivot, the two-year averaged cumulative NH3 loss under sprinkler fertigation was 6.80 kg N ha−1, was similar to that under broadcasting and 32.55 % higher than that under banding. With the increase of N application rates, the cumulative NH3 loss increased but NH3 loss rate decreased. For different treatments, NH3 loss rate ranged from 1.76 % to 3.88 %. Cumulative NH3 loss for a growing season was only 5.00 kg N ha−1 for sprinkler fertigation at dusk, which could be significantly reduced by 20.38 % and 23.31 % compared with those in the morning and at noon, and even lower than that under banding. Meanwhile, instantaneous NH3 loss flux had a significantly positive correlation with temperature in the two years. Based on our results, in order to minimize NH3 loss, sprinkler fertigation at dusk was more recommendable to the urea application for alfalfa in the North China.

A cross-sectional study on knowledge and attitude of schoolteachers about epilepsy in Saudi Arabia

Introduction: Epilepsy is a chronic brain disease characterised by intermittent nervous system derangement due to sudden excessive cerebral neuron discharge that results in almost instantaneous sensation disruption and loss of consciousness. There is a clear lack of epilepsy information among the general population. This study was carried out with an aim to examine the knowledge, attitude and practice of schoolteachers towards epilepsy. Materials and Methods: This cross-sectional survey was administered to 433 schoolteachers working in the Al-Qassim region of Saudi Arabia from October to December 2020. A 20-item pretested validated questionnaire was distributed as a Google survey link, and the data collected were analysed using SPSS version 22. P < 0.05 was considered statistically significant. The Chi-square test was used to evaluate the categorical variables. Results: Around two-thirds of the teachers (35.2%) gained their information about epilepsy from public resources such as newspapers, television and the internet, and around half of them (53.1%) gained their information about epilepsy from multiple resources, namely from doctors, public resources and parents of students with epilepsy. Almost all teachers (99.3%) acknowledge that epilepsy is not a contagious disease, and more than half of the participants (58.4%) believed that there are multiple causes of epilepsy, including genetics, head trauma, infection, brain tumour and insanity. Conclusion: The study showed that teachers' knowledge of epilepsy was promising, but still, there are gaps in knowledge and attitude towards first aid management. There is a need to address this issue with the training of schoolteachers with the cooperation of local health professionals.

Analysis and Modeling of Instantaneous Magnetizing Power of Ferromagnetic Cores in the Time Domain

This letter presents an approach to the analysis and modeling of instantaneous magnetizing power of ferromagnetic samples in a uniaxial magnetic field. The analysis is based on the calculation of constitutive components (absorbed and oscillatory) of this power using harmonic components of the sample's magnetic field strength. The modeling is based on Bertotti's model of power loss separation, completely in the time domain. The approach was applied to the experimental results obtained for a toroidal sample made of grain-oriented electrical steel for controlled shape of the magnetic flux density waveform at frequencies of 1 and 50 Hz. In addition to the introduction of the approach, this letter presents measured waveforms of the magnetic field and flux density to which the approach has been applied. The waveforms of the corresponding instantaneous magnetizing powers and its components as well as instantaneous power loss components are presented. The main features of the approach are also discussed.

Numerical Solution of Parabolic Partial Differential Equation by Using Finite Difference Method

In the real world, many physical problems like heat equation, wave equation, Laplace equation and Poisson equation are modeled by partial differential equations (PDEs). A PDE of the form ut = α uxx, (α &gt; 0) where x and t are independent variables and u is a dependent variable; is a one-dimensional heat equation. This is an example of a prototypical parabolic equation. The heat equation has analytic solution in regular shape domain. If the domain has irregular shape, computing analytic solution of such equations is difficult. In this case, we can use numerical methods to compute the solution of such PDEs. Finite difference method is one of the numerical methods that is used to compute the solutions of PDEs by discretizing the given domain into finite number of regions. Here, we derived the Forward Time Central Space Scheme (FTCSS) for this heat equation. We also computed its numerical solution by using FTCSS. We compared the analytic solution and numerical solution for different homogeneous materials (for different values of diffusivity α). There is instantaneous heat transfer and heat loss for the materials with higher diffusivity (α) as compared to the materials of lower diffusivity. Finally, we compared simulation results of different non-homogeneous materials.

Fluid-Structure Interaction Simulation of an Intra-Atrial Fontan Connection.

Simple SummaryA fluid-structure interaction (FSI) simulation of an intra-atrial Fontan connection was performed. Power loss and pressure drop results fluctuated less during the FSI simulation than during the simulation run with rigid walls, but there were no observable differences in time-averaged pressure drop, connection power loss or hepatic flow distribution. These results suggested that employing a rigid wall is a reasonable assumption when evaluating time-averaged hemodynamic quantities of the Fontan connection under resting breath-held flow conditions.Total cavopulmonary connection (TCPC) hemodynamics has been hypothesized to be associated with long-term complications in single ventricle heart defect patients. Rigid wall assumption has been commonly used when evaluating TCPC hemodynamics using computational fluid dynamics (CFD) simulation. Previous study has evaluated impact of wall compliance on extra-cardiac TCPC hemodynamics using fluid-structure interaction (FSI) simulation. However, the impact of ignoring wall compliance on the presumably more compliant intra-atrial TCPC hemodynamics is not fully understood. To narrow this knowledge gap, this study aims to investigate impact of wall compliance on an intra-atrial TCPC hemodynamics. A patient-specific model of an intra-atrial TCPC is simulated with an FSI model. Patient-specific 3D TCPC anatomies were reconstructed from transverse cardiovascular magnetic resonance images. Patient-specific vessel flow rate from phase-contrast magnetic resonance imaging (MRI) at the Fontan pathway and the superior vena cava under resting condition were prescribed at the inlets. From the FSI simulation, the degree of wall deformation was compared with in vivo wall deformation from phase-contrast MRI data as validation of the FSI model. Then, TCPC flow structure, power loss and hepatic flow distribution (HFD) were compared between rigid wall and FSI simulation. There were differences in instantaneous pressure drop, power loss and HFD between rigid wall and FSI simulations, but no difference in the time-averaged quantities. The findings of this study support the use of a rigid wall assumption on evaluation of time-averaged intra-atrial TCPC hemodynamic metric under resting breath-held condition.

Design of clean energy dispatching system for wind and solar storage

In order to optimize the capacity dispatch of energy storage system in grid-connected wind-solar hybrid power generation system, a method for optimizing the capacity of hybrid energy storage system composed of supercapacitors and batteries in grid-connected wind-solar hybrid power generation system is proposed by utilizing the generation data of wind power and photovoltaic and the dispatch data of power grid. Based on the method of Particle Swarm Optimizer (PSO), it was simulated that wind-solar hybrid power joined into the dispatch according to the rules of dispatch system. The best power dispatch was achieved by multi-objective particle swarm optimization (MPSO). The results show that the accuracy of capacity optimization of energy storage system can be improved by considering both the total continuous power loss and the instantaneous power loss. The hybrid energy storage system composed of supercapacitors and batteries can improve the overall security and economy of the power grid.

Impact of modulation strategies on the lifetime estimation of impedance source inverter in wind power system

The lifetime of the wind power converter is strongly influenced by the thermal behaviour of the power devices and their mission profile. This paper focuses on the fundamental-frequency thermal cycles of the Impedance source inverter based wind power generation system. Impedance source inverters, e.g., quasi-Z source inverter, with two different modulation strategies have been explored to improve the reliability from reducing the power devices fundamental thermal cycles. A comparative evaluation of power losses, thermal performance, number of cycles to failure of the power devices in qZSI wind power system is performed for the two strategies. Such comparison can guide researchers to select a better modulation strategy to improve the lifetime of impedance source inverter so as to reduce the system cost and maintenance rate. The modulation effects on instantaneous power loss and thermal cycle in different wind speeds are evaluated. Simulations are carried out to validate the theoretical analysis and comparison.

Experimental research methodology for the deformation of RC frame under instantaneous loss of column

In recent years, numerous experimental and especially numerical studies have been conducted in order to study the mechanisms of the resistance of reinforced concrete building frames to progressive collapse during the instantaneous removal of one of the columns. Analysis of these researches shows that almost all study deals with strength performance of RC structural elements under quasi static or instantaneous loss of column. At the same time, a number of numerical and analytical studies of the progressive collapse behaviour of steel moment frames as well as fragments of RC moment frames indicates that loss of bearing capacity of structures can be associated with buckling behaviour. Therefore, using the theory of functional similarity, a physical model of the reinforced concrete frame of a multi-storey building and a methodology for experimental studies of the buckling and fracture of this structural system under instantaneous loss of the corner column are proposed.

Physical Assessment of the Magnetic Path Length of Energy Loss Testers

Magnetic energy losses of SiFe sheets are determined by the standardized methods of single sheet tester (SST) or Epstein tester (ET). According to IEC standards, the total power consumption is measured in Watt-metric ways, and the portion that concerns the homogeneously magnetized region(s) is estimated on a nominal value l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> of the so-called conventional effective magnetic path length (PL). A clear definition of PL is lacking-a suggestion being provided here. Standards express l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> through the dependence between the magnetic field strength H and the magnetization current. However, they apply the same value l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> also for the determination of losses P. From the viewpoint of physics, two PL quantities l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m,H</sub> and l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m,P</sub> would be preferable. The problematic is enhanced by the fact that the flux distribution within the magnetic circuit of a tester may change dynamically during the period of time, with induction changes B(t). This means that the physical PL L is a function of time, according to a PL function L[B(t)]. Finally, dynamic changes in flux distributions prove to be distinctly influenced by hysteretic mechanisms which means that L[B(t)] exhibits loop character. The resulting complexity indicates that the concept of PL is not promising, if high accuracy of testing is demanded. However, for purposes of material comparisons, optimum PL values LOPT may be suitable that are determined for individual material families. Analyses of instantaneous loss power values p(t) indicate that energy dissipation is weak during high induction. Thus, determinations of LOPT should be focussed on moderate induction. The ET is characterized by strong modifications of 3-D flux distributions which means that individual values LOPT would be needed. On the other hand, the SST shows a clear design. For moderate induction, some energy dissipation is expected to occur within the yoke region. This indicates that LOPT exceeds the conventional value of 450 mm, in weak ways.