Universal Power Research Articles

A Safe Hosmer-Lemeshow Test

This article proposes an alternative to the Hosmer-Lemeshow (HL) test for evaluating the calibration of probability forecasts for binary events. The approach is based on e-values, a new tool for hypothesis testing. An e-value is a random variable with expected value less or equal to one under a null hypothesis. Large e-values give evidence against the null hypothesis, and the multiplicative inverse of an e-value is a p-value. Our test uses online isotonic regression to estimate the calibration curve as a ‘betting strategy’ against the null hypothesis. We show that the test has power against essentially all alternatives, which makes it theoretically superior to the HL test and at the same time resolves the well-known instability problem of the latter. A simulation study shows that a feasible version of the proposed eHL test can detect slight miscalibrations in practically relevant sample sizes, but trades its universal validity and power guarantees against a reduced empirical power compared to the HL test in a classical simulation setup. We illustrate our test on recalibrated predictions for credit card defaults during the Taiwan credit card crisis, where the classical HL test delivers equivocal results.

Watermelons on the half-plane

We study the watermelon probabilities in the uniform spanning forests on the two-dimensional semi-infinite square lattice near either the open or closed boundary to which the forests can or cannot be rooted, respectively. We derive universal power laws describing the asymptotic decay of these probabilities with the distance between the reference points growing to infinity, as well as their non-universal constant prefactors. The obtained exponents match with the previous predictions made for the related dense polymer models using the Coulomb gas technique and conformal field theory, as well as with the lattice calculations made by other authors in different settings. We also discuss the logarithmic corrections some authors argued to appear in the watermelon correlation functions on the infinite lattice. We show that the full account for diverging terms of the lattice Green function, which ensures the correct probability normalization, provides the pure power law decay in the case of semi-infinite lattice with the closed boundary studied here, as well as in the case of infinite lattice discussed elsewhere. The solution is based on the all-minors generalization of the Kirchhoff matrix tree theorem, the image method and the developed asymptotic expansion of the Kirchhoff determinants.

On the nature of noble gas - metal bond in silver aggregates.

The aim of this paper is to extend the study of the nature of the bond between noble gas to nano- and sub nanoscale silver aggregates. In the framework of DFT-PAW calculations implemented in the abinit package, we carried out a thorough investigation on the nature of the bond between the six noble gases NG (He, Ne, Ar, Kr, Xe and Rn) and numerous neutral silver aggregates Agn from the single atom Ag1 to the nanoparticle Ag147 using atoms-in-molecules (AIM) dual functional analysis,. We evaluated the impact of the silver aggregate size, the adsorption site and of the noble gas on the Ag-NG bond. Our study concluded on the favored adsorption of heavier noble gases (Kr, Xe and Rn) over that of lighter noble gases (He, Ne and Ar) on any aggregate size due to an enhanced chemical contribution in the bond. For these heavier noble gases, in accordance with studies carried out on surfaces, we noted their preferential adsorption on on-top sites rather than on hollow sites, which further evidences the chemical contribution to the bond. Moreover, the slight positive Bader charge on these heavier noble gases implies an electron transfer from the noble gas to the silver atom. Noble gas adsorption is favored on smaller, few-atom, two-dimensional clusters rather than on larger three-dimensional nanoparticles. Finally, we identified a universal power law with a unique exponent linking bond length and electronic density at the bond critical point for all aggregate sizes, noble gases and adsorption sites.

Structural, conductivity, and complex impedance properties of the La0.7Ag0.3Mn1−xZnxO3 (x = 0 and x = 0.025) samples

In this paper, the structural and dielectric properties of La0.7Ag0.3Mn1−xZnxO3 (x = 0 and 0.025) manganite system are investigated. The x-ray diffraction analysis confirms that all compounds crystallized in the rhombohedral structure with R3̄C space group. The effects of Zn substitution on the crystal structure and the dielectric properties were studied by using the impedance spectroscopy technique at room temperature and over a wide range of frequencies. Electrical conductance curves are found to obey the Jonscher universal power law. We note a decrease in the conductivity when increasing the Zn content from x = 0 to x = 0.025. This behavior can be associated with the introduction of a very low concentration of a non-magnetic Zn ion, which distorts the octahedral MnO6 neighbor. The analysis of the complex impedance spectra reveals a single semicircular arc reflecting a non-Debye-type relaxation process. We conclude from the best fits that the equivalent circuit formed in our case is defined as a grain resistance Rg in series with a parallel combination of grain boundary resistance Rgb and constant phase element impedance (ZCPE).

Novel Universal Power Electronic Interface for Integration of PV Modules and Battery Energy Storages in Residential DC Microgrids

This paper introduces the novel concept of a highly versatile smart power electronic interface for fast deployment of residential dc microgrids. The proposed approach has bidirectional power flow control capabilities, wide operating voltage range, and high efficiency resulting from the topology morphing control utilization. This enables universal compatibility with the majority of the commercial 60- and 72-cell photovoltaic modules, as well as the efficient charge/discharge control of the 24 V and 48 V battery energy storages using the same hardware platform. The proposed concept features fully autonomous operation where switching between the photovoltaic and battery interfacing modes is automatically done using the input source identification algorithm. Moreover, the proposed universal interface converter employs droop control and solid-state protection, making it fully compatible with the emerging standards and requirements for power electronic systems used in dc microgrid environments. A 350 W prototype was developed and tested in the residential 350 V dc microgrid with droop control to validate the proposed concept experimentally.

Classification in the european legal systems of exclusive competence of the Rabbinical court in Jewish divorce

In Israel in the family questions is applicable the religious law of each confession. To the Jewish people is applicable the religious Jewish law which dates back to the Pentateuch of Moses. According to that law the divorce is not only the legal, but also the sacral act. The divorce between the Jewish people is realized in Israel in the religious rabbinical court. The divorce in the secular court does not have the legal effect from the point of view of religious Jewish law. If the Jewish spouses wish to get divorced in an european country where the religious courts do not have the public power, so two concepts come into conflict: the concept of the territorial sovereignty of the State authority and the concept if the universal power of religion over its followers regardless of their residence. In private international law this conflict expresses in the conflict of characterization. The requierement of the religious support of divorce is considered as the substance in law of Israel and as the procedure in law of european countries (Russia, Germany, France). This article is dedicated to the conflict of civilization, competence and/or characterization, which consists in the question whether to consider the religious rabbinical court as exclusive competent and to refer the spouses to get divorced in Israel or to consider the secular court in an european country as an equivalent replacement of the religious court. Since the French Court of Cassation rendered its famous decision in the case of Levinçon 1903 where this question was first posed this question has still not found its unambiguous solution.

Quantifying Social Interventions for Combating COVID-19 via a Symmetry-Based Model.

The COVID-19 pandemic has revealed new features in terms of substantial changes in rates of infection, cure, and death as a result of social interventions, which significantly challenges traditional SEIR-type models. In this paper we developed a symmetry-based model for quantifying social interventions for combating COVID-19. We found that three key order parameters, separating degree (S) for susceptible populations, healing degree (H) for mild cases, and rescuing degree (R) for severe cases, all display logistic dynamics, establishing a novel dynamic model named SHR. Furthermore, we discovered two evolutionary patterns of healing degree with a universal power law in 23 areas in the first wave. Remarkably, the model yielded a quantitative evaluation of the dynamic back-to-zero policy in the third wave in Beijing using 12 datasets of different sizes. In conclusion, the SHR model constitutes a rational basis by which we can understand this complex epidemic and policymakers can carry out sustainable anti-epidemic measures to minimize its impact.

Investigation of Transport Mechanism and Nanostructure of Nylon-6,6/PVA Blend Polymers

A casting technique was used to prepare poly(vinyl alcohol) (PVA) blend polymers with different concentrations of Nylon-6,6 to increase the free-volume size and control the ionic conductivity of the blended polymers. The thermal activation energy for some blends is lower than that of pure polymers, indicating that their thermal stability is somewhere in between that of pure Nylon-6,6 and pure PVA. The degree of crystallinity of the blend sample (25.7%) was lower than that of the pure components (41.0 and 31.6% for pure Nylon-6,6 and PVA, respectively). The dielectric properties of the blended samples were investigated for different frequencies (50 Hz-5 MHz). The σac versus frequency was found to obey Jonscher's universal power law. The calculated values of the s parameter were increased from 0.53 to 0.783 for 0 and 100 wt.% Nylon-6,6, respectively, and values less than 1 indicate the hopping conduction mechanism. The barrier height (Wm) was found to increase from 0.33 to 0.72 for 0 and 100 wt.% Nylon-6,6, respectively. The ionic conductivity decreases as the concentration of Nylon-6,6 is blended into PVA because increasing the Nylon-6,6 concentration reduces the number of mobile charge carriers. Positron annihilation lifetime (PAL) spectroscopy was used to investigate the free volume's nanostructure. The hole volume size grows exponentially with the concentration of Nylon-6,6 mixed with PVA. The Nylon-6,6/PVA blends' free-volume distribution indicates that there is no phase separation in the blended samples. Mixing PVA and Nylon-6,6 resulted in a negative deviation (miscible blends), as evidenced by the interaction parameter's negative value. The strong correlation between the free-volume size and other macroscopic properties like ionic conductivity suggests that the free-volume size influences these macroscopic properties.

Single-polymer dynamics of starch-like branched ring polymers in steady shear flow

The stretching dynamics and dynamical behaviors of individual branched ring polymer (BRP), a coarse-grained model for some types of the starch, in steady shear flow are studied by using a hybrid mesoscale simulation approach that combines multiparticle collision dynamics with standard molecular dynamics. By analyzing the stretched configuration of BRPs, we find the polymer size increases nonmonotonically with increasing branch length. Meanwhile, the decrease of the alignment angle of the stretched configuration of BRPs follows a universal power law during the first downward phase as the shear rate increases. Constructing the three-dimensional surface of the polymer's ring backbone and tracing the temporal fluctuations of the surface's normal vector along the simulation trajectory, the tumbling and tank-treading motion are clearly reflected by periodic and non-periodic changes of the normal vector. Interestingly, these temporal changes are much more regular than that of the gyration tensor. Thus, a novel cross-correlation function, which is the correlation between fluctuations of the normal vector along the flow direction and the velocity-gradient direction, is proposed to analyze the tumbling motion that usually coexists with the tank-treading motion. This function can naturally address the fails of traditional method that analyzing the tumbling motion by determining the correlation of temporal fluctuations of the gyration tensor Gαα. By analyzing the dynamical behaviors of BRPs, diverse dependences of the tumbling frequency ωTB and tank-treading frequency ωTT on the shear rate γ̇ are observed at a wide range of shear rates and polymer sizes. Furthermore, our simulations also reveal that the tank-treading motion is more stable than the tumbling motion for small-branch-size BRPs but the tumbling motion is more stable than the tank-treading motion for large-branch-size BRPs.

Correlation between Acoustic Emission and Stress Evolution during Single Twin Boundary Motion in Ni–Mn–Ga Magnetic Shape Memory Single Crystal

Stress evolution and related acoustic emission (AE) in modulated 10Mmartensite are simultaneously studied during compression forced motion of Type I and Type II single twin boundary (TB) resulting in microstructure reorientation and large deformation. The single TB of both types is formed in the same sample and traveled the same volume. The single boundary exhibits random jerky movement and for Type I the stress fluctuation can be directly correlated to AE signal. The AE during the single TB motion is an avalanche‐like process surmounting the obstacles – crystal defects. The amplitudes of AE are approximately five times higher for Type I compared to Type II. The energy amplitudes of AE events follow the universal power law with different coefficients for Type I and Type II TB. The peak rate well correlates with stress fluctuation during TB motion. Large differences observed for the same sample indicate a different mechanism of pinning and ultimately a different mechanism of Type I and Type II TB motion.

Innovative model of the universal power law of dielectric and ac conductivity behavior of nonferroelectric materials

In predicting the dielectric and ac conductivity behavior of nonferroelectric materials, the novel model proposed in this study, which considers two components with conductivities in the low-frequency and high-frequency regimes in series, is more accurate than Jonscher's expression and provides insight into the related physical significance. New scaling parameters are uncovered, clarifying the diversity and misunderstanding of the existing parameters and the related physical significance. The demonstration of the relationship of loss peak frequency and intersection frequency of low- and high-frequency regimes of frequency dependence of conductivity is pioneering, providing deep insight into understanding the mechanism concerning the frequency dependence of charge carriers hopping and innovative perspectives with respect to the fundamental science of material dielectric and ac conductivity responses.

Inference, Prediction, & Entropy-Rate Estimation of Continuous-Time, Discrete-Event Processes.

Inferring models, predicting the future, and estimating the entropy rate of discrete-time, discrete-event processes is well-worn ground. However, a much broader class of discrete-event processes operates in continuous-time. Here, we provide new methods for inferring, predicting, and estimating them. The methods rely on an extension of Bayesian structural inference that takes advantage of neural network's universal approximation power. Based on experiments with complex synthetic data, the methods are competitive with the state-of-the-art for prediction and entropy-rate estimation.

Dielectric, Optical, and Magnetic Behaviors of Magnesium Iron-Based Double Perovskite

The multiferroic nature of the Mg2FeNbO6 complex oxide ceramic, prepared by a mixed oxide reaction route is being communicated. A phase transformation to the tetragonal symmetry was identified from refinement analysis. The optical band gap was estimated to be 1.58 eV with the direct allowed transition consideration. From the temperature-dependent dielectric parameter study, magnetic phase transitions at various Tc values were seen, together with some glassy dynamics. The CIS spectroscopy revealed the dominance of grains towards the complex impedance response of the composite. The conductivity of the compound was found to be following Jonscher’s universal power quite ideally. The plot of μ B /unit mass vs manifests itself as a weak but well-saturated magnetic ordering in the ceramic, with a low retentivity value of 0.0286 emu gm−1. The multiferroic nature of the oxide material is confirmed by the existence of a room temperature(P–E) hysteresis loop, with remnant polarization of Pr = 1.2 μC Cm−2.

Design of universal power supply and distribution ground test system based on modularity

To solve the problems of high functional requirement, complex structure and poor versatility of manned spacecraft power supply and distribution ground test equipment, a modular universal ground power supply system (PSS) is designed. The functions of the system cover the functions of wire instruction opening, parameter measurement and state detection of the interface between the manned spacecraft and the ground equipment, and realize the universal and extensible configuration. This paper provides a general architecture design method for complex manned spacecraft power supply and distribution ground test system.

Experimental validation of the Kibble-Zurek mechanism on a digital quantum computer

The Kibble-Zurek mechanism (KZM) captures the essential physics of nonequilibrium quantum phase transitions with symmetry breaking. KZM predicts a universal scaling power law for the defect density which is fully determined by the system’s critical exponents at equilibrium and the quenching rate. We experimentally tested the KZM for the simplest quantum case, a single qubit under the Landau-Zener evolution, on an open access IBM quantum computer (IBM-Q). We find that for this simple one-qubit model, experimental data validates the central KZM assumption of the adiabatic-impulse approximation for a well isolated qubit. Furthermore, we report on extensive IBM-Q experiments on individual qubits embedded in different circuit environments and topologies, separately elucidating the role of crosstalk between qubits and the increasing decoherence effects associated with the quantum circuit depth on the KZM predictions. Our results strongly suggest that increasing circuit depth acts as a decoherence source, producing a rapid deviation of experimental data from theoretical unitary predictions.

Deforming devices with a power drive made of a shape memory material Design solutions, calculation and design procedure

The article presents engineering solutions developed to create deforming devices with a power drive made of a shape memory material. As an example, the paper considers designs of a press, a stamp press made using new designs of multi-link power drives. A method is proposed for engineering a universal multi-link power drive with power elements made of a thermally thin shape memory material. The paper provides the analysis of thermal processes in power elements of various shapes, geometric dimensions and using different methods of their heating (current transmission heating, convective and radiant heat exchange) to determine the efficiency of the engineered devices. Processing and operational properties of thermally thin power elements of a multi-link power drive are investigated. To determine their qualitative and quantitative indicators, a measuring bench was created with such functions as recording the amperage, temperature change, displacement, and developed forces on a single time scale. A relationship between the heating rate, rate of operating force development and return deformation force was found. A line of universal power drives with a developed deformation force of 500–10000 N and a displacement of 1.0–8.0 mm was created based on the calculations performed with the results of their testing and use in existing models of deforming devices presented.

Performance Analysis of Universal Power Quality Conditioner Systems Based on Seven-level NPC Inverter Using PD-SPWM with Fuzzy Control Scheme

This paper presents novel Unified Power Quality Conditioner (UPQC) system based on seven-level Neutral Point Clamped (NPC) inverter using combined PD-SPWM and fuzzy control scheme. The proposed UPQC is adopted to mitigate source current harmonics and compensate all voltage disturbances simultaneously. It is designed by the combination of series and shunt Active Filters (AFs) connected by a common DC link capacitor. The DC voltage at common DC bus is maintained constant using proportional integral voltage controller. The Synchronous Reference Frame (SRF) method is used to get the shunt APF reference signals and the power reactive theory (P-Q theory) for the series APF. Conventional control schemes require complex calculations, the use of intelligent systems help to reduce the control system size and the operation complexity. The shunt and series Active Power Filter (APF) reference signals derived from the control algorithm are injected in Fuzzy intelligent controllers to generate switching signals. The functionality of proposed UPQC system and its control system is evaluated using Matlab-Simulink software and SimPowerSystem Toolbox under various operation conditions in cases of most common power quality problems such as voltage sag, voltage swell, current harmonic compensation of nonlinear loads and unbalanced load. The simulation results show UPQC performances to improve the power quality in steady and transient conditions operation at the point of common coupling on power distribution under unbalanced and distorted voltage conditions.

Study of dielectric and electrical properties in Co-(Fe–Ce-Nd) nanosized spinel ferrites

Ce–Nd doped Cobalt ferrite nanoparticles having composition CoFe2-2xCexNdxO4 (where 0.00 ≤x ≤ 0.10) were prepared by co-precipitation method. X-ray diffraction study confirms the formation of single-phase spinel ferrite. Temperature dependent dielectric and electrical properties has been studied with in the frequency range of 20Hz to 3 MHz. Dielectric constant and dielectric loss decrease as frequency increased while ac conductivity exhibit increasing trend with increasing frequency. The alternating current (AC) conductivity data were successfully modeled by using universal Jonscher's power law which implies that hopping of charge carriers is the governing mechanism in the conduction. Impedance study using Nyquist plots shows that grain boundary resistance is higher than the grain interior resistance. Diameter of Nyquist plots decreases with increasing temperature indicating the decrease in impedance and increase in conductivity. DC resistivity show decreasing trend with increasing temperature revealing semiconductor nature of synthesized nanoparticles. Current–Voltage measurements exhibit nonlinear hysteresis loop which authenticate the occurrence of resistance switching effect in synthesized composition.

Dielectric Behaviour and Electrical Conductivity of α-BiNbO4 and β-BiNbO4 Ceramics

In this work, orthorhombic (α-BiNbO4) and triclinic bismuth niobate (β-BiNbO4) ceramics were prepared by a wet chemical route. The structure of the obtained powders was characterised by X-ray diffraction and the morphology by scanning electron microscopy. The dielectric measurements were performed in the radiofrequency region, at different temperatures, using the impedance spectroscopy technique. The α-BiNbO4 sample presented a temperature-dependent relaxation process, with the corresponding activation energy being calculated through the Arrhenius equation. The AC conductivity dependence on the frequency was in agreement with Jonscher’s universal power. The conduction mechanism in the α-BiNbO4 compound is governed by two processes, which can be ascribed to a hopping transport mechanism. The correlated barrier hopping model until 280 K and the non-overlapping small polaron tunnelling model above 280 K are the most suitable models to describe the conductivity of this sample. In the β-BiNbO4 compound, the motion of mobile charge carriers involves localised hopping between neighbouring sites.

Enhanced Performance of On-board EV Battery Charger with Universal Power Supply

This paper is intended to provide enhanced features of onboard EV battery chargers in terms of improved power quality feature, reduced voltage stress, reduced filter size, high efficiency and fast dynamic response for universal input voltage range (85–265 V). The proposed configuration comprises of three-level quadratic converter suitable to provide high voltage gain. The detailed operation, analysis and control scheme of the proposed converter rated for 3.2 kW, 400 V are studied under simulation and hardware in a loop environment. The on-board charger performances are assessed by charging a 40 Ah lithium ion EV battery under different charging modes. The state of charge of battery decides converter operating mode i.e. constant current and constant voltage mode to charge the battery. Enhancement in the onboard charger is observed in both operating modes tested for wide variation in supply voltages. The results reveal that the operation of converter depicts unity power factor operation, improvement in supply current harmonics and controlling output voltage/current. Under both operating modes, the proposed charger draws sinusoidal supply current from ac mains and its THD is reduced to specified limit prescribed by IEC-61000-3-2. Furthermore, the charger performance is also investigated for EV battery charging operation at wide input voltage variations and found satisfactory.