Instantaneous Loss Research Articles

The Effects of Steel Lamination Core Losses on 3D Transient Magnetic Fields

A three-dimensional (3D) transient finite element analysis (FEA) approach taking into account the effects of steel lamination core loss is proposed. When using the T-Ω method, the effects of lamination core loss are considered by introducing an additional field component in lamination regions, which is derived from the instantaneous core loss in the time domain. The proposed approach is validated by two applications in terms of the power-balance testing, that is, the input power increase due to the core-loss effects must be equal to the total core loss.

Characteristic equation of a hybrid (PV-T) active solar still

A hybrid (PV-T) active solar still is a combination of solar still and flat plate collector (FPC) integrated with glass–glass photovoltaic module. In this paper, two analytical methods are used to establish characteristic equation of hybrid (PV-T) active solar still based on annual experimental observations. In method-1, linear and non-linear curves are plotted for instantaneous gain efficiency ( η i ) with respect to x = ( T w − T a) / I( t) which is a representative factor of climatic and operational parameter. In method-2, a characteristic equation for solar still similar to FPC i.e. η i = A + B ∙ {( T w − T a) / I( t)} + C ∙ {( T w − T a) 2 / I( t)} has been found using a matrix method. Further, both the methods are used for estimation of instantaneous loss efficiency ( η iL). All these equations are established by assuming steady state condition for thermal testing of solar still. The comparative performance of these two methods has also been estimated in terms of root mean square percentage (RMS) error. It has been observed that the performance of non-linear characteristic equation is better than linear characteristic equation.

Derivative loss for Kirchhoff equations with non-Lipschitz nonlinear term

In this paper we consider the Cauchy boundary value problem for the integro-differential equation utt − m

|∇u|2 dx  u =0 in
× [0, T ) with a continuous nonlinearity m : [0,+∞) → [0,+∞). It is well known that a local solution exists provided that the initial data are regular enough. The required regularity depends on the continuity modulus of m. In this paper we present some counterexamples in order to show that the regularity required in the existence results is sharp, at least if we want solutions with the same space regularity of initial data. In these examples we construct indeed local solutions which are regular at t = 0, but exhibit an instantaneous (often infinite) derivative loss in the space variables.

Characteristic equation of a passive solar still

The characteristic equation has been used for experimental results of a passive solar still to generate linear and non-linear characteristic equations for winter and summer conditions. The different angles of inclination of condensing cover (15°, 30°, 45°) have been chosen for winter and summer conditions both. It has been observed that the passive solar still with inclination of 45° gives better performance both in winter and summer respectively. Different water depths (0.04, 0.08, 0.12, and 0.16 m) have also been taken for solar still with 30° inclination angle for summer weather condition. Comparisons of instantaneous gain and loss efficiencies at 0.01 and 0.04 m water depths for a 15° inclination angle have also been made to show the effect of water depth on the performance of solar stills. It was found that a lower water depth gives better efficiency, which is in agreement with many investigators. The instantaneous gain and loss efficiency curves have been simultaneously analyzed to give a better understanding of the performance of solar stills. The proposed method will be used to standardize the design and operational parameter of a passive solar still, i.e. angle of inclination and water depth for highest yield for a given climatic condition.

Optimum Codebook Design and Average SEP Loss Analysis of Spatially Independent and Correlated Feedback Based MISO Systems With Rectangular QAM Constellation

In this correspondence, we present an optimum codebook design algorithm that minimizes the loss in average symbol error probability (SEP) of a spatially correlated multiple-input single-output (MISO) system with finite-rate feedback under both perfect and imperfect channel estimate assumptions. Towards the goal of designing an optimum codebook that minimizes average SEP (ASEP) loss due to finite-rate channel quantization, we derive the distortion function as a first order approximation of the instantaneous SEP loss. Utilizing high resolution quantization theory and assuming perfect channel estimation at the receiver, we analyze the loss in ASEP for spatially independent and correlated finite-rate feedback transmit beamforming MISO systems with M1 times M2-QAM constellation. We then consider the high-SNR regime and show that the loss associated with quantizing the spatially independent channels is related to the loss associated with quantizing the spatially correlated channels by a scaling constant given by the determinant of the correlation matrix. We also present simulation results that illustrate the effectiveness of the new codebook design and validate the derived analytical expressions for ASEP loss.

Definition of Instantaneous Dielectric Loss Factor and Digital Algorithm for Online Monitoring

Among the digital algorithms currently available for online monitoring of the dielectric loss factor of power apparatus, there are unavoidable limitations, such as that most of them must strictly meet the synchronous sampling criterion simultaneously with a precondition that the power frequency must be invariable in the sampling periods. This paper presents a unique definition and a corresponding digital algorithm of the instantaneous dielectric loss factor. The theoretical basis of the algorithm is also deduced. In a nonstationary signal environment where power frequencies are randomly variable, the algorithm can accurately track the instantaneous frequency of power signals, recursively calculate the parameters of parallel equivalent circuit, and, finally, figure out the waveform of the instantaneous dielectric loss factor. Simulations and experimental results show that the proposed algorithm renders good application performance without being affected by the limitations incurred from synchronous sampling and harmonics.

Facet bending driven by the planar crystalline curvature with a generic nonuniform forcing term

We study crystalline driven curvature flow with spatially nonuniform driving force term. We assume special monotonicity properties of the driving term, which are motivated by our previous work on Berg's effect. We consider special initial data which we call ‘bent rectangles.’ We prove existence of solutions for a generic forcing term as well as generic subclass of bent rectangles. We show the initially flat facets may begin to bend, provided, loosely speaking, they are too large. Moreover, depending on the initial configuration we notice instantaneous loss of regularity of the moving curve.

Ionospheric effects on GPS signals in the Arctic region using early GPS data from Thule, Greenland

Thule, Greenland, is near the magnetic North Pole, and therefore any high‐speed GPS data recorded there are of great potential import in specifying the severity of ionospheric effects on modern commercial navigation and ranging systems that must transit the polar latitudes. While there have now been many sets of GPS receiver data recorded at high latitudes, including GPS‐IGS data routinely taken from Thule, Greenland, virtually all of these data have not been recorded at a high enough rate to measure the actual amplitude and phase scintillation effects. One notable exception is very early data taken from Thule, in the late 1980s and early 1990s, a period of high solar activity where data were taken from a L1/L2 dual‐frequency receiver having the capability of tracking only one GPS satellite at a time, on both the L1 and the L2 channels with a data sampling rate of 20 Hz. The receiver phase‐locked loop bandwidth was 16 Hz; thus, the sampling rate was not fast enough to insure that all the spectral components up to the receiver bandwidth were measured. We report on a new analysis of these “old” data illustrating that the rapid rates of change in total electron content (TEC) and high values of the amplitude scintillation index, S4, reported from these data are very relevant today with the advent of modern civilian aircraft routinely flying in the polar latitudes. For instance, we see a very high correlation between individual amplitude fades on the GPS L1 and L2 channels, indicating that users who suffer instantaneous signal loss on one frequency may not be able to use the secondary frequency to recover the GPS signal modulation, since it, too, will suffer an almost identical fade. Also, the occurrence of large, rapid changes in TEC, previously reported from these high‐speed Thule GPS data, has been confirmed and may limit precise positioning in the polar cap latitudes.

Downlink transmission rate-control strategies for closed-loop multiple-input multiple-output systems

A novel downlink transmission rate-control and feedback reduction strategy for closed-loop multiple-input multiple-output (MIMO) multiple-input multiple-output wireless systems is presented. Unlike conventional systems that use signal to interference plus noise ratio at the receiver as an indicator of channel quality, we propose using instantaneous MIMO capacity as an indicator for the downlink transmission rate-control. A set of instantaneous capacity thresholds is first chosen such that the expected weighted capacity loss because of thresholding effects are minimised. While computing the thresholds, we also consider the quality of service and weight function to meet different traffics and user needs. Then a set of codebooks can be constructed minimising the overall capacity loss with given quality of service constraint. Simulation results show that, with only four data rate-control bits, our algorithm gives only 12% capacity loss in 4×4 MIMO systems and almost twice better than the current IS-856 standard in single-input single-output systems. In case of 5-bit feedback scenario, the proposed algorithm outperforms conventional systems by minimising instantaneous capacity loss.

In situ measurements of the evolution of young sea ice

We present data from in situ measurements of the salinity evolution of young sea ice in the Arctic. The measurements were carried out with very high vertical and temporal resolution over the course of a few days until the ice had reached a thickness of around 20 cm. The measured bulk salinity profiles show that during ice growth, sea‐ice salinity is continuous across the ice‐ocean interface and that there is no instantaneous loss of salt at the advancing front. Measured salt fluxes emanating from the ice are as high as 90 g m−2 h−1 during the first few hours of new ice formation and are roughly half as large during later stages of the experiments. The bulk salinity within the ice decreases continuously with time from the ocean water salinity to a near–steady state value of around 4 parts per thousand (ppt). These results are interpreted with ideas from mushy layer theory using a Rayleigh number to analyze gravity drainage as the driving mechanism for the observed salt loss. In our experiments, gravity drainage occurs for a critical Rayleigh number of around 10, in close agreement with earlier theoretical and experimental studies.

Acetylation of histone H4K4 is cell cycle regulated and mediated by HAT3 in Trypanosoma brucei

Post-translational histone modifications have been studied intensively in several eukaryotes. It has been proposed that these modifications constitute a ‘histone code’ that specifies epigenetic information for transcription regulation. With a limited number of histone-modifying enzymes, implying less redundancy, Trypanosoma brucei represents an excellent system in which to investigate the function of individual histone modifications and histone-modifying enzymes. In this study, we characterized the acetylation of lysine 4 of histone H4 (H4K4), the most abundant acetylation site in T. brucei histones. Because of the large sequence divergence of T. brucei histones, we generated highly specific antibodies to acetylated and unmodified H4K4. Immunofluorescence microscopy and Western blots with sorted cells revealed a strong enrichment of unmodified H4K4 in S phase and suggested a G1/G0-specific masking of the site, owing to non-covalently binding factors. Finally, we showed that histone acetyltransferase 3 (HAT3) is responsible for H4K4 acetylation and that treatment of cells with the protein synthesis inhibitor cycloheximide led to an almost instantaneous loss of unmodified H4K4 sites. As HAT3 is located inside the nucleus, our findings suggest that newly synthesized histone H4 with an unmodified K4 is imported rapidly into the nucleus, where it is acetylated, possibly irreversibly.

Progressive collapse of multi-storey buildings due to sudden column loss—Part II: Application

The companion paper presents the principles of a new design-oriented methodology for progressive collapse assessment of multi-storey buildings. The proposed procedure, which can be implemented at various levels of structural idealisation, determines ductility demand and supply in assessing the potential for progressive collapse initiated by instantaneous loss of a vertical support member. This paper demonstrates the applicability of the proposed approach by means of a case study, which considers sudden removal of a ground floor column in a typical steel-framed composite building. In line with current progressive collapse guidelines for buildings with a relatively simple and repetitive layout, the two principal scenarios investigated include removal of a peripheral column and a corner column. The study shows that such structures can be prone to progressive collapse, especially due to failure of the internal secondary beam support joints to safely transfer the gravity loads to the surrounding undamaged members if a flexible fin-plate joint detail is employed. The provision of additional reinforcement in the slab over the hogging moment regions can generally have a beneficial effect on both the dynamic load carrying and deformation capacities. The response can be further improved if axial restraint provided by the adjacent structure can be relied upon. The study also highlights the inability of bare-steel beams to survive column removal despite satisfaction of the code prescribed structural integrity provisions. This demonstrates that tying force requirements alone cannot always guarantee structural robustness without explicit consideration of ductility demand/supply in the support joints of the affected members, as determined by their nonlinear dynamic response.

An example of dB/dt characteristics of the dynamic magnetic loss parameter

AbstractFerrite cores are used for power electronics circuits operating under excitation conditions of frequency ranging from hundreds of kilohertz to several tens of megahertz. Development of a mathematical model enabling the estimation of the power loss of ferrites in high‐frequency regions, contributes to the designing of power circuits. The power loss in high‐frequency regions consists of hysteresis and dynamic magnetic losses. Although hysteresis loss does not depend on the excitation frequency, the dynamic magnetic loss increases with increasing excitation frequency. The dynamic magnetic loss parameter, λf, has been introduced for identifying the power loss in high‐frequency regions. In this study, λf − dB/dt characteristics are experimentally obtained by a newly introduced hysteresis model that uses a normal distribution function. It is found that the λf − dB/dt characteristics do not depend on the size of B − H loops. The instantaneous power loss of a ferrite core in the high‐frequency region can be calculated using the λf − dB/dt characteristics. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Performance Evaluation of Inter-Vehicle Packet Relay for Road-Vehicle Communication in Fast Mobile Environment

In conventional road-vehicle communication systems, user terminals in the vehicles have to directly connect to wireless access points (APs). However, vehicle speeds are so fast that the channel condition between the terminals and the APs constantly changes because of changing path loss and time-varying fading. In this paper, to compensate for such deterioration, we propose to reduce the relative speed between the terminals and the APs by an inter-vehicle packet relay technique. If a terminal can send data via other vehicles running at lower speeds, the relative speed will decrease, which suppresses the dynamic range of path loss and deterioration by fading. We, first, validate our method by a numerical analysis using a statistical path-loss model. The numerical analysis verifies that our method is able to suppress deterioration caused by path loss and time-varying fading. However, in the numerical analysis, geometric propagation of paths is not considered; instantaneous and rapid loss changes are not considered. Therefore, we evaluate our method by computer simulations using a geometric propagation model. In the simulations, phase difference between multiple paths and loss fluctuation within one frame duration affect the performance. From the results of the simulations, we validate our method. Furthermore, we investigate the combination of our method and the selection diversity technique, which can suppress channel fluctuation and may enhance the performance of our method. Moreover, we measure interference in the overlapped zone between two AP areas. From the measurement, we show that our packet relays do not cause a problem in interference between areas.

A Stochastic Framework for Rate-Distortion Optimized Video Coding Over Error-Prone Networks

This paper proposes a complete stochastic framework for RD optimal encoder design for video over error-prone networks, which applies to any motion-compensated predictive video codec. The distortion measure has been taken as the mean square error over an ensemble of channels given an estimate of the instantaneous packet loss probability. We show that 1) the optimal motion compensated prediction, in the MSE sense, requires computation of the expected value of the reference frames, and 2) calculation of the MSE (distortion measure) requires computation of the second moment of the reference frames. We propose a recursive procedure for the computation of both the expected value and second moment of the reference frames, which are together called the stochastic frame buffer. Furthermore, we propose a stochastic RD optimization method for selection of the optimal macroblock mode and motion vectors given the instantaneous packet loss probability. If available, channel feedback can also be incorporated into the proposed stochastic framework. However, the proposed framework does not require a feedback channel to exist, and when it exists, it does not have to be lossless. In the absence of any packet losses, the proposed stochastic framework reduces to the well-known deterministic RD optimization procedures. One possible application of the optimal stochastic framework would be for multicast streaming to an ensemble of receivers. Experimental results indicate that the proposed framework outperforms other available error tracking and control schemes.

Radiation safety design for SSRL storage ring

In 2003, the Stanford Synchrotron Radiation Laboratory (SSRL) had upgraded its storage ring to a 3rd generation storage ring (SPEAR3). SPEAR3 is deigned to operate at 500-mA stored beam current and 3-GeV energy. The 234-m circumference SPEAR3 ring utilizes 60-cm-thick concrete lateral walls, 30-cm-thick concrete roof, as well as 60- or 90-cm-thick concrete ratchet walls. A total of 3.5 × 10 15 e - / y will be injected into the ring with an injection power of 4 W and an injection efficiency of 75%. Normal beam losses occur due to both injection and stored beam operations in the total of 20 low loss as well as 3 high loss limiting apertures. During the 6-min injection period, an instantaneous power loss of 0.05 W occurs at each low loss aperture. When averaged over the operational year, the loss of both the injection and the stored beams is equivalent to an average loss of 2 mW at each low loss aperture. On the other hand, the average losses in the high loss apertures are 16 mW for the injection septum, 47 mW for the beam abort dump, and 13 mW for the ring stoppers. The shielding requirements for losses in the new ring were based on a generic approach that used both FLUKA Monte Carlo particle generation and transport code and empirical computer codes and formulae.

An Efficient Method for the Evaluation of Secular Effects in the Perturbed Keplerian Motion

Binary systems subject to generic perturbations evolve on quasiperiodic orbits. We derive the most generic class of perturbations, which allows the evaluations of secular effects via generalized complex true and eccentric anomaly parameters, by use of the residue theorem. Such perturbations include both the generic Brumberg force and various linear contributions to the conservative dynamics of compact binaries, up to the second post-Newtonian order. As an example, we compute the self-spin contribution to the luminosity due to gravitational radiation of a compact binary consisting of Galactic black holes, the most important type of source for LISA. This translates to simply calculating the residue of the instantaneous energy loss in the origin of the complex parameter plane, which illustrates the power of the presented method.

Bayesian traffic dynamics and packet loss prediction for video over IP networks

Designing good network-adaptive, error resilient video coders for IP networks is a challenging task. Video data packets can be lost as a consequence of congestion in the network, causing a degradation in video quality at the receiver side. Predicting the packet loss probability is therefore an important step in the design of an efficient network-adaptive video coder. In this paper, we present a novel Bayesian-based approach that can dynamically predict the instantaneous packet loss probability as well as estimate the probability distribution of the cross-traffic rate. The method utilises observed losses and end-to-end measurements of the packet delays to predict the time-varying cross-traffic rate in the network. The posterior probability for the cross-traffic rate is established by using the Bayes formulation. To obtain this, the probability of delays conditioned on the cross-traffic are derived by decomposing the delays with a multi-scale wavelet transform. The probability of the observed losses conditioned on the cross-traffic are derived by studying the queueing properties in the network. The predicted packet loss probability is then derived from the posteriori distribution of the cross-traffic rate and the expected queueing behaviour. An algorithm for obtaining the numerical solution is also given. Two sets of simulations are performed to demonstrate the effectiveness of the proposed method. The first set is designed to test the performance of the proposed Bayesian method for dynamically predicting the packet loss probabilities. The results of the predicted packet loss probabilities are then compared with the ground truth of packet loss values for three different network traffic generators. In the 2nd set of simulations, the proposed method and the two-state Markov model are incorporated separately into a network-adaptive video codec whose coding rate is adapted to the predicted packet loss probabilities. The reconstructed videos using these two methods are then compared.

Elucidation of the intrinsic loss arising from switch output capacitance Coss in ultra-high-speed low-loss power converters

Attempts to drive down the switching losses of hard-switched unipolar devices by increasing gate drive current levels are ultimately limited by the device output capacitance, which thus represents an intrinsic loss. The paper presents an in-depth analysis of the charging and discharging of the output capacitance and the associated loss producing mechanisms. It is shown that energy is stored in the depletion layer of the device during turn-off and then dissipated as heat during the turn-on process. The instantaneous power dissipated in the device is thus different to the instantaneous power loss measured at the device terminals, although the total energy loss over one complete turn-off and turn-on cycle is still faithfully reproduced. An analytical approach to determining the intrinsic switching loss due to the output capacitance is presented and verified by experimental results and by TCAD simulation. It is shown that around 20% of the total switching losses arise from the intrinsic output capacitance loss under fast-switched inductive load conditions. A comparison of Si and SiC FET devices demonstrates the potential for SiC power devices to provide an energy efficient option for very high frequency switching.

Importin α/β Mediates Nuclear Transport of a Mammalian Circadian Clock Component, mCRY2, Together with mPER2, through a Bipartite Nuclear Localization Signal

Circadian rhythms, which period is approximately one day, are generated by endogenous biological clocks. These clocks are found throughout the animal kingdom, as well as in plants and even in prokaryotes. Molecular mechanisms for circadian rhythms are based on transcriptional oscillation of clock component genes, consisting of interwoven autoregulatory feedback loops. Among the loops, the nuclear transport of clock proteins is a crucial step for transcriptional regulation. In the present study, we showed that the nuclear entry of mCRY2, a mammalian clock component, is mediated by the importin alpha/beta system through a bipartite nuclear localization signal in its carboxyl end. In vitro transport assay using digitonin-permeabilized cells demonstrated that all three importin alphas, alpha1 (Rch1), alpha3 (Qip-1), and alpha7 (NPI-2), can mediate mCRY2 import. mCRY2 with the mutant nuclear localization signal failed to transport mPER2 into the nucleus of mammalian cultured cells, indicating that the nuclear localization signal identified in mCRY2 is physiologically significant. These results suggest that the importin alpha/beta system is involved in nuclear entry of mammalian clock components, which is indispensable to transcriptional oscillation of clock genes.