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Copyright of Studies in Conservation is the property of Taylor & Francis Ltd 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.)

Critical sections of a paper machine such as the wet end presses, size press, on-machine coater, and reel may be required to undergo large and fast load changes in normal operation. These changes must result in minimum disturbance to the ingoing sheet tension or nip roll speed in order to avoid sheet breaks or wrinkling. This paper evaluates two disturbance-rejection control techniques, one using disturbance feedforward (or disturbance input decoupling) based on a nip-pressure disturbance observer and the other using a two-degrees-of-freedom controller. Evaluations were done in both a press section and a size press section of a lightweight paper machine, and the results showed that both methods are very effective in reducing the maximum speed deviation to about 10% of the values without compensation and can operate combined with torsional oscillation compensation without interference between them. [ABSTRACT FROM AUTHOR]

The article presents a study regarding the protective enclosures for art on paper, archives and library materials. It highlights the importance of the components of the protective enclosures that are able to compensate environmental fluctuations. Results show that constructing protective boxes from cellulose-based materials rather than Twinwall Polypropylene material appears to be the better choice in respect to climatic stability.

Torsional oscillations bound the velocity loop bandwidth (BW) of industrial drives and servo systems, deteriorating the transient response to commands and disturbances. This is especially harmful in multidrive systems like paper machines that need to run synchronized. This paper presents two methods to dynamically compensate the torsional oscillations produced by the compliant components between the motor and the load: either a notch filter or an acceleration feedback based on the rigid-body Luenberger observer. The evaluation includes the effect of reducer backlash, whereby both time and frequency domain responses are used to compare the benefits of each technique in a typical paper machine section. Results show that both methods, if properly tuned, are effective techniques to reduce torsional oscillations and are robust to parameter variations. [ABSTRACT FROM AUTHOR]

Chemical gradients that run axially in a microfluidic channel often contain undesirable high-frequency concentration variations, or noise, that results from mechanical and thermal fluctuations in the system. In this paper, we describe a passive microfluidic component called an ‘expansion channel’ (EC), that removes high frequency noise through axial dispersion. We show that the behavior of the filter can be modeled analytically, using an expression for the transfer function of the microfluidic channel, derived by Xie et al.(Y. W. Xie, L. Chen and C. H. Mastrangelo, Lab Chip, 2008, 8, 907–912). The use of ECs to remove noise from gradients formed in enyzmatic assays in a microfluidic channel is demonstrated. The resulting data quality is improved which enables better fits to chemical models and more accurate analysis. ECs should be very effective in removing noise from axial concentration gradients found in many microfluidic applications, e.g.liquid chromatography, biochemistry, and chemotaxis studies. [ABSTRACT FROM AUTHOR]

The following response to the discussion of the above mentioned paper is divided into two parts: (1) a response to the issue of our comparison of the ‘apparent period of specimen oscillation’, t, and the natural vibration period of a cracked specimen,T, and (2) a verification of the applicability of our model to ‘short time-to-fracture’ tests, which Rokach has questioned, due to a lack of knowledge of Hopkinson bar techniques. [ABSTRACT FROM AUTHOR]

Recent developments based on the flow acceleration/deceleration, mechanical responses of the pipe-wall material and leakage are analysed in order to better understand the pipe system response under transient conditions for pressurised flows, in terms of amplitude, phase and shape. These events have been performed by using collect data in transient tests obtained for different pipe system characteristics (two experimental facilities and a real-life system). Current commercial transient solvers cannot accurately predict the head oscillations in pipes with non-elastic rheological pipe-wall behaviour, such as polyethylene PE, whose application in water supply systems has increased during the last years. Experimental procedures are carried out aimed at the collection of data sets of dynamic effects through pressure time variation and flow velocity fields. Pressure transients that naturally occur in pipe systems propagate back and forth in the pipes and carry information about features of the system, such as the presence of a leak, providing a potential tool for leak detection. [ABSTRACT FROM AUTHOR]

I give a simple analysis of the game that I previously published in Scientific American which shows the paradoxical behavior whereby two losing games randomly combine to form a winning game. The game, modeled on a random walk, requires only two states and is described by a first-order Markov process. [ABSTRACT FROM AUTHOR]

Earthquake sequencing studies allow us to investigate empirical relationships among spatio-temporal parameters describing the complexity of earthquake properties. We have recently studied the relevance of Markov chain models to draw information from global earthquake catalogues. In these studies, we considered directed graphs as graph theoretic representations of the Markov chain model, and analyzed their properties. Here, we look at earthquake sequencing itself as a directed graph. In general, earthquakes are occurrences resulting from significant stress-interactions among faults. As a result, stress-field fluctuations evolve continuously. We propose that they are akin to the dynamics of the collective behaviour of weakly-coupled non-linear oscillators. Since mapping of global stress-field fluctuations in real time at all scales is an impossible task, we consider an earthquake zone as a proxy for a collection of weakly-coupled oscillators, the dynamics of which would be appropriate for the ubiquitous Kuramoto model. In the present work, we apply the Kuramoto model to the non-linear dynamics on a directed graph of a sequence of earthquakes. For directed graphs with certain properties, the Kuramoto model yields synchronization, and inclusion of non-local effects evokes the occurrence of chimera states or the co-existence of synchronous and asynchronous behaviour of oscillators. In this paper, we show how we build the directed graphs derived from global seismicity data. Then, we present conditions under which chimera states could occur and subsequently, point out the role of Kuramoto model in understanding the evolution of synchronous and asynchronous regions. [ABSTRACT FROM AUTHOR]

The article presents discussion on analysis of the dynamic responses for a pre-cracked three-point bend specimen. Theoretical part presents a very simple model of the impact specimen. As it was shown in the discussion, accuracy of this model and its applicability for the short time to fracture tests is questionable. An example that demonstrates a weak accuracy of the model is also presented. Most controversial section of the discussion is comparison between the vibration period of the cracked specimen and the apparent period of specimen oscillation.

Despite the significance of resource levelling, project managers lack various ways to smooth resource usage fluctuation of a repetitive construction project besides changing resource usage. Tolerating interruptions is an effective way to provide flexibility for a schedule but is ignored when solving resource levelling problems. Therefore, this paper investigates the impacts of interruptions on resource usage fluctuation and develops an integrated approach that simultaneously integrates two scheduling adjusting processes: changing resource usage and tolerating interruptions. In this paper, two interruption conditions are proposed to identify which activities are suitable to be interrupted for smoothing resource usage fluctuation. The traditional resource levelling model is modified to a new scheduling model by incorporating interruptions. A two-stage GA-based scheduling algorithm is developed by integrating changing resource usage and tolerating interruptions. A commonly used pipeline project is adopted to illustrate the steps of the proposed approach and demonstrate its effectiveness and superiority through comparison with previous studies. A large-scale project further verifies the usability of the proposed approach. The results confirmed the feasibility to smooth resource usage fluctuation by interruptions, and the integrated approach can achieve a more competitive resource levelling result. [ABSTRACT FROM AUTHOR]

Errors in gas concentration measurements by infrared gas analysers can occur during eddy-covariance campaigns, associated with actual or apparent instrumental drifts or to biases due to thermal expansion, dirt contamination, aging of components or errors in field operations. If occurring on long time scales (hours to days), these errors are normally ignored during flux computation, under the assumption that errors in mean gas concentrations do not affect the estimation of turbulent fluctuations and, hence, of covariances. By analysing instrument theory of operation, and using numerical simulations and field data, we show that this is not the case for instruments with curvilinear calibrations; we further show that if not appropriately accounted for, concentration biases can lead to roughly proportional systematic flux errors, where the fractional errors in fluxes are about 30-40% the fractional errors in concentrations. We quantify these errors and characterize their dependency on main determinants. We then propose a correction procedure that largely -- potentially completely -- eliminates these errors. The correction, to be applied during flux computation, is based on knowledge of instrument calibration curves and on field or laboratory calibration data. Finally, we demonstrate the occurrence of such errors and validate the correction procedure by means of a field experiment, and accordingly provide recommendations for in situ operations. The correction described in this paper will soon be available in the EddyPro software (www.licor.com/eddypro). [ABSTRACT FROM AUTHOR]

This paper utilizes the theory of quantum diffusion to analyze the electron probability and spreading width of a wavepacket on each layer in a two-dimensional (2D) coupled system with edge disorder, aiming to clarify the effects of edge disorder on the stability of the electron periodic oscillations in 2D coupled systems. Using coupled 2D square lattices with edge disorder as an example, we show that, the electron probability and wavepacket spreading width exhibit periodic oscillations and damped oscillations, respectively, before and after the wavepacket reaches the boundary. Furthermore, these electron oscillations exhibit strong resistance against disorder perturbation with a longer decay time in the regime of large disorder, due to the combined influences of ordered and disordered site energies in the central and edge regions. Finally, we numerically verified the universality of the results through bilayer graphene, demonstrating that this anomalous quantum oscillatory behavior is independent of lattice geometry. Our findings are helpful in designing relevant quantum devices and understanding the influence of edge disorder on the stability of electron periodic oscillations in 2D coupled systems. [ABSTRACT FROM AUTHOR]

While Ising criticality in classical liquids has been firmly established both theoretically and experimentally, much less is known about criticality in liquids in which the growth of the correlation length is frustrated by finite-size effects. A theoretical approach for dealing with this issue is the random-field Ising model (RFIM). While experimental critical-exponent values have been reported for magnetic samples (here, we consider γ , ν and η), little experimental information is available for critical fluctuations in corresponding liquid systems. In this paper, we present a study on a binary liquid consisting of 3-methyl pyridine and heavy water in a very light-weight porous gel. We find that the experimental results are in agreement with the theoretical predictions from the RFIM. [ABSTRACT FROM AUTHOR]

In order to study the combustion instability of solid rocket motors, the vibration-acoustic vibration-burning rate oscillation-thrust oscillation coupling system of solid rocket motors is analyzed. In this paper, a numerical model covering the pressure oscillation, combustion, pseudo-one-dimensional fluid field, and overall thrust is built. We investigate the thrust oscillation caused by projectile structure vibration and the response characteristics of thrust oscillation. By conducting a sine sweep test, we obtain the response function of thrust in relation to pressure oscillation. A physical experiment shows that the calculated frequency response function is consistent with the experimental results. [ABSTRACT FROM AUTHOR]

In this paper, theoretical and numerical analysis of a transonic flow field of critical flow Venturi nozzles according to the ISO 9300 standard is performed. Deviations of the flow field from an estimate based on one dimensionality are clarified. While the theoretical analysis allows prediction of these deviations, the numerical analysis allows quantification of their influence. The main studied phenomena include the local supersonic compression in transonic expansion and the Prandtl-Meyer expansion. The tendency of the flow field to spatial oscillations is shown, alongside the ability of the system to damp these oscillations. [ABSTRACT FROM AUTHOR]

In the design of shield tunnels, it is expected that a design can be more economical as more site investigation data are available. Nevertheless, the cost of site investigation will also increase as more site investigation data are required. It is thus important to assess the potential benefit of a site investigation program before it is conducted considering the uncertainty in the soil properties and the site investigation outcomes. In this paper, a probabilistic framework is suggested to assess the effectiveness of a site investigation program for the design of shield tunnels through the random field theory. An efficient method based on the generalized extreme value distribution is used to calculate the failure probability of the tunnel, through which the expected benefit from a site investigation program can be estimated conveniently. The result shows that a site investigation program is more valuable when a greater target design reliability index is needed. The expected benefit from a site investigation program increases as the borehole intensity increases, and it also increases as the scale of fluctuation of the soil properties increases. The method suggested in this paper provides a useful tool for planning borehole layout for the design of shield tunnels, which is promising for the optimization of site investigation. [ABSTRACT FROM AUTHOR]

Turbulent flow between a flexible wall and a solid surface containing a backward-facing step (BFS) was investigated using digital particle image velocimetry and high-speed photography. Stationary sheet of paper under tension was positioned above the solid surface in proximity to the BFS. The incoming air flow emerged from a planar nozzle that was located in the solid wall upstream of the BFS. Flows corresponding to two values of the Reynolds number (3,000 and 3,600) based on the step height and the maximum flow velocity at the step location were characterized in terms of patterns of time-averaged velocity, out-of-plane vorticity, streamline topology, and turbulence statistics. In addition, paper sheet oscillation was characterized using high-speed photography. For the control case of a solid upper wall with the geometry that represented the time-averaged paper profile, hydrodynamic frequencies were characterized using unsteady pressure measurements. Frequencies of the natural vibration modes of the paper sheet were well separated from the hydrodynamic frequencies corresponding to the oscillations of the shear layer downstream of the BFS. As the inflow velocity increased, the paper sheet was pulled closer to the solid surface, which resulted in increased confinement of the incoming jet. The flow reattachment length calculated on the basis of time-averaged flow patterns increased with the increasing Reynolds number. [ABSTRACT FROM AUTHOR]

We investigate the respective role of variations in subpolar deep water formation and Nordic Seas overflows for the decadal to multidecadal variability of the Atlantic meridional overturning circulation (AMOC). This is done by analysing long (order of 1000 yr) control simulations with five coupled climate models as well as sensitivity experiments performed with one of the models, in which we suppress the variability of either subpolar deep water formation or Nordic Seas overflows. For all models, the maximum influence of variations in subpolar deep water formation is found at about 45° N, while the maximum influence of variations in Nordic Seas overflows is rather found at 55° N to 60° N. Regarding the two overflow branches, the influence of variations in the Denmark Strait overflow is, for all models, substantially larger than that of variations in the overflow across the Iceland-Scotland-Ridge. The influence of variations in subpolar deep water formation is, on multi-model average, larger than that of variations in the Denmark Strait overflow. This is true both at 45° N, where the maximum standard de viation of decadal to multidecadal AMOC variability is located for all but one model, and at the more classical latitude of 30° N. At 30° N, variations in subpolar deep water formation and Denmark Strait overflow explain, on multi-model average, about half and one third respectively of the decadal to multidecadal AMOC variance. [ABSTRACT FROM AUTHOR]

Memristors have several chaotic dynamic models and have been used successfully in various fields, including secure communication systems, information storage, and artificial neural networks. The memristor-based four-dimensional chaotic (FDMC) systems generate unpredictable and intricate time domain signals. Parameter fluctuations in the FDMC system may give birth to chaos, making it difficult to suppress. Stabilizing chaos in the FDMC system improves the circuit's performance. This paper synthesizes a novel time-efficient chatter-free nonlinear robust adaptive control (NLRAC) technique that stabilizes chaos in the FDMC system affected by time-varying unknown bounded exogenous disturbances and model uncertainties. The proposed NLRAC strategy decimates the time-varying unknown bounded exogenous disturbances and model uncertainties effects; it establishes a faster, smoother state-variable trajectories convergence to the zero vicinity. The theoretical analysis and mathematical proofs are based on the Lyapunov stability technique. Computer simulation results show that the proposed NLRAC technique effectively brings the FDMC system's state-variable trajectories to zero with reduced fluctuations for control input signals and state-variable trajectories. This feedback controller's attribute enhances closed-loop stability performance, improves precision, and reduces risk overshoot. The paper includes comparative computer simulation results to endorse the proposed controller performance. [ABSTRACT FROM AUTHOR]

This paper presents an in-depth analysis of the oscillation phenomenon occurring in multi-chip parallel automotive-grade power modules under short-circuit conditions and investigates three suppression methods. We tested and analyzed two commercial automotive-grade power modules, one containing two chips and the other containing a single chip, and found that short-circuit gate oscillations were more likely to occur in multi-chip parallel packaged modules than in single-chip packaged modules. Through experimental and simulation analyses, we observed that gate oscillations were mainly caused by the interaction between internal parasitic parameters of the module and the external drive circuit, and we found that high drive resistance and low common emitter inductance between parallel chips could effectively suppress gate voltage oscillations. We also analyzed the two mainstream suppression schemes, increasing the drive gate resistance and placing the drive capacitors in parallel. Unfortunately, we found that these suppression schemes were not ideal solutions because both schemes changed the switching characteristics of the power module. As an alternative, we propose a simple and effective solution that involves adding parallel connections between the parallel chips. Simulation calculations showed that this optimized method reduced the emitter inductance between parallel chips in the upper bridge arm by about 30% and in the lower bridge arm by 35%. Through short-circuit experiments conducted at different DC bus voltages, it has been verified that the new optimized solution effectively resolves gate oscillation issues without affecting the switching characteristics of the power module. [ABSTRACT FROM AUTHOR]

Winds over the South China Sea (SCS) are primarily responsible for the observed variability in sea level anomalies (SLAs) in the Singapore Strait (SS). The present study focuses on remote forcing contributing to local mean sea level changes in the SS in seasonal and inter-annual scales, and relating the long term mean sea level variation to El Niño/ENSO. As Tanjong Pagar (TP) tide station in the SS has nearly 23.5 yr (1984-2007) of time series data with less data gaps, this data was subject to harmonic and sea level analyses. The mean sea level changes suggest that the fluctuations are quasi-periodic. Rising and falling of sea level is noticed atleast 7 times in a period of 15 yr, with 3 distinct sharp falls (1984-1987, 1989-1992 and 1995-1996) and 4 sharp rises (1987-1988, 1992-1993, 1994-1995 and 1997-1999). These sea level falls are related to El Niño events. When we segregated the results into 2 time spans, we find that from 1984 to 1999 the sea level was on the rising trend in spite of sharp falls, and from 1999 to 2007 on gradual falling trend. More or less similar trend was observed by other researchers for the SCS with altimetry data. During the El Niño periods of 1987 and 1992, the inter-annual MSL variability is the highest, of the order of 7 cm. In one of the events, sea level recovered from a fall of 60mm (in 1987) to a rise of 40mm (in 1988). During 1992 to 1999, sea level was continuously on rising trend (from -50mm to +60mm), except in one year (1995-1996). The analysis shows a MSL rise rate of 15.7mmyr-1, which is very closer to MSL in the SCS. The average rate of sea level rise around Singapore as shown by the Tanjong Pagar tidal station is 1.6mmyr-1, and this matches with the global sea level rise. [ABSTRACT FROM AUTHOR]

Wind and wave effects on tidal current structure and turbulence throughout the water column are examined using an upward-looking acoustic Doppler current profiler (ADCP). The instrument has been deployed on the seafloor of 20-m depth, off the North-Eastern French coast in the Eastern English Channel over 12 tidal cycles and covered the period of the transition from mean spring to neap tide and forcing regimes varied from calm to moderate storm conditions. During storms, we observed gusty winds with magnitude reached 15ms-1 and wave height reached up to 1.3 m. Analysis of velocity spectra revealed a noticeable contribution of wind-induced waves to spectral structure of velocity fluctuations within the upper 10-m layer. Near the surface, stormy winds and waves produced a significant intensification of velocity fluctuations, particularly when the sustained wind blew against the ebb tide flow. As during wavy periods the variance-derived Reynolds stress estimates might include a wave-induced contamination, we applied the Variance Fit method to obtain unbiased stresses and other turbulent quantities. Over calm periods, the turbulent quantities usually decreased with height above the seabed. The stresses were found to vary regularly with the predominantly semidiurnal tidal flow, with the along-shore stress being generally greater during the flood flow (∼ 2.7Pa) than during the ebb flow (∼ -0.6Pa). The turbulent kinetic energy production rate, P, and eddy viscosity, Az, followed a nearly regular cycle with close to a quarter-diurnal period. As for the stresses, near the seabed, we found the maximum values of estimated quantities of P and Az to be 0.1Wm-3 and 0.5m2 s-1, respectively, during the flood flow. Over the storm periods, we found the highest stress values (∼ -2Pa) during ebb when tidal currents were opposite to the southwesterly winds while, during the flood, the surface stresses slightly exceeded those estimated for a calm period. [ABSTRACT FROM AUTHOR]

This paper proposes a method of reducing oscillations for integrations of the artificial potential field algorithm in real-time robot manipulator path planning using proximity sensors. Proximity sensing is a technology that has the potential to play an essential role in the development of robotics. It can fulfill the promise of safe, robust, and autonomous systems in industry and everyday life alongside humans by enabling the ability of online and fast-reacting motions without the need for visual mapping. In this context, the artificial potential field technique is one of the most suitable methods for path planning due to its simplicity of application and efficiency in real-time systems without the need for global mapping. Despite its efficiency, this technique is known to be susceptible to problems such as local minima and oscillations within the overall path. To solve this problem, a method of reducing the oscillations is proposed by modifying the direction of the repulsive force to follow its orthogonal projection onto the attractive force. Since with conventional repulsive motions, the robot only moves in one direction, opposite to the obstacles, this approach has better exploitation of the redundancy space to maintain the task motion and is less likely to get stuck in local minima. The effectiveness of this proposed method is demonstrated through simulations on real robot manipulators in comparison with the original artificial potential field technique. [ABSTRACT FROM AUTHOR]

With the development of the energy structure of the power system, the characterization of the observed oscillation in the power system has steadily evolved. With the increasingly high penetration of distributed energy sources and power electronic devices, such as the photovoltaic, wind power and charging pile, the basic mechanism, frequency ranges and propagation of oscillation would become more dynamic and complex. Therefore, the traditional parameter estimation, as well as the suppression methods would also suffer from dynamic oscillations. To this end, this paper first investigates the oscillation propagation and typical events caused by the oscillations. Next, the oscillation model estimation method including the model‐based and data‐driven based methods is discussed. The benefits and difficulties of various parameter estimate techniques are highlighted. Under this context, the validity and limitations of the current power system stability are summarized. Furthermore, the different oscillation damping and mitigation measures are compared, and the major adaptability and limitations are listed for the specific application scenarios. Conclusions are drawn, and the wideband oscillation becomes the future research objective where the future work is presented at the end of the paper. [ABSTRACT FROM AUTHOR]

There have been only a few studies that allow us to estimate the contribution of newly-created reservoirs to greenhouse gas budgets. In particular, information is limited for understanding the spatiotemporal variation of N2O flux and the underlying mechanisms in the littoral zone where complex biochemical processes are induced by water level fluctuations. A study was carried out at five different water levels (deep water area, shallow water area, seasonally flooded area, control site for seasonally flooded area and non-flooded area) at the littoral zone of a temperate reservoir using the static chamber technique. Seasonal and spatial variations of N2O flux and environmental factors were monitored throughout the growing season including a flood event during summer rains. The N2O flux ranged from -2.29 to 182.47 µg m-2 h-1. Non-flooded dry land emitted more N2O than flooded land, no matter whether it was permanently or seasonally flooded. However, no significant difference was observed between seasonally flooded sites and their control sites. Wind speed, air temperature, soil water content, dissolved oxygen in water and soil nitrate influenced N2O flux significantly. In order to know the contrasting characteristics of N2O and CH4 fluxes in the littoral zone of the reservoir, results were compared with a previous study on CH4 emission carried out at the same sites and time with comparable methods. It showed that N2O flux and CH4 flux was influenced by distinct factors and in differing ways. This work highlights the complexity of N2O flux at the littoral zone. The different response ways of N2O and CH4 to environments implies the big challenge of greenhouse gas emission control through ecosystem management. [ABSTRACT FROM AUTHOR]

A packaging system using the material of honeycomb paperboard, when it is subjected to drop impact, is a major concern to manufacturers as it relates to the maximum stress causing failure. In this work, the full-field dynamic responses of product packaging system are measured and analyzed in detail with the simulation and experiment method. First, on the basis of theoretical analysis, a series of honeycomb paperboards with different size dimension of paper honeycomb core had been set up in the FEA software. Then a packaging system which is made up of rigid body and deformable body had been analyzed. The results show that the physical dimension of paper honeycomb core has a great effect on its impact resistance: with the increasing size dimension, the peak acceleration has a quickly alteration within 10 mm-20 mm, but in other region it has an effect in the form of up and down fluctuation. At the same time, with the increasing size dimension, honeycomb paperboard can improve the energy absorption ability in the condition of elastic deformation. The research results can be used to optimize the structure design and material selection. [ABSTRACT FROM AUTHOR]

We generalize the stochastic theory of hierarchical clustering presented in Paper I by Lapi & Danese to derive the (conditional) halo progenitor mass function and the related large-scale bias. Specifically, we present a stochastic differential equation that describes fluctuations in the mass growth of progenitor halos of given descendant mass and redshift, as driven by a multiplicative Gaussian white noise involving the power spectrum and the spherical collapse threshold of density perturbations. We demonstrate that, as cosmic time passes, the noise yields an average drift of the progenitors toward larger masses, which quantitatively renders the expectation from the standard extended Press and Schechter (EPS) theory. We solve the Fokker–Planck equation associated with the stochastic dynamics, and obtain as an exact, stationary solution, the EPS progenitor mass function. Then we introduce a modification of the stochastic equation in terms of a mass-dependent collapse threshold modulating the noise, and solve analytically the associated Fokker–Planck equation for the progenitor mass function. The latter is found to be in excellent agreement with the outcomes of N-body simulations; even more remarkably, this is achieved with the same shape of the collapse threshold used in Paper I to reproduce the halo mass function. Finally, we exploit the above results to compute the large-scale halo bias, and find it in pleasing agreement with the N-body outcomes. All in all, the present paper illustrates that the stochastic theory of hierarchical clustering introduced in Paper I can describe effectively not only halos' abundance, but also their progenitor distribution and their correlation with the large-scale environment across cosmic times. [ABSTRACT FROM AUTHOR]

In the search for the critical point of strongly interacting matter, one of the key tools is to look at event-by-event fluctuations of different event observables expecting their non-monotonic behavior. It is crucial for the experiments to eliminate an influence of the trivial volume fluctuations on the physics observables of interest. This may be done by an application of the accurate centrality selection and by means of special measures using different estimators of initial conditions. It is also feasible to apply some theoretical approaches in estimation of all the possible sources of unwanted fluctuations. In this paper, we present results obtained in the developed Monte-Carlo model of particle production with particle emitting sources being interacting quark–gluon strings of finite length in rapidity space. Implemented strings dynamics in rapidity causes non-uniform string density over it and brings fluctuations to the system event-wise. The model also takes into account, event-by-event, the string fusion phenomenon caused by string overlap in the transverse plane. It is this process of fusion that modifies string fragmentation characteristics and changes the mean values of multiplicities and transverse momenta of produced particles. Using this model and Monte-Carlo event generator PYTHIA, the calculations were done for the strongly intensive quantities , and . [ABSTRACT FROM AUTHOR]

With the introduction of an ever-larger share of renewable but intermittent energy sources on electrical grids, hydraulic turbines are more often used as network stabilizers. In such a role, they are generally operated in off-design operations like speed-no-load (SNL). No energy is extracted from the flow at SNL operation, but the runner rotates at the synchronous speed linked to the electrical grid. The flow inside the runner of low-head turbines operating at SNL is often dominated by a columnar vortex array that may induce damaging pressure fluctuations. This paper presents the study of a control device to mitigate those vortices. At SNL, the small guide vane opening leads to a high swirl in the runner generating secondary flows such as columnar vortices and backflows. The proposed concept is to move SNL operation toward a higher guide vane opening and hence lower swirl, preventing the formation of a columnar vortex array. Lowering the input swirl of SNL is accomplished by opening up the guide vanes while using a control device to limit the discharge. The control device, like a spoiler on an aircraft wing, is introduced on the guide vanes to generate added head losses, significantly decreasing the discharge in high guide vane angles. This paper compares the hydrodynamics of the flow in a propeller turbine with different spoiler geometries. The study is based on both Reynolds-averaged Navier-Stokes (RANS) and unsteady RANS (URANS) flow simulations. It highlights how such devices can successfully mitigate columnar vortices and their associated pressure fluctuations on runner blades. [ABSTRACT FROM AUTHOR]

Experimental studies have shown that many natural and artificial systems need to maintain stable oscillations during application, but the occurrence of oscillation quenching phenomenon will destroy the oscillation activity of the system and hinder the normal operation of the system. In this paper, to solve the important problem of oscillation quenching leading to system paralysis, the weighted average function of oscillators is applied to each oscillator as an external feedback, which is an extension of the mean-field feedback [N. Zhao and Z. Sun, Int. J. Bifurcation Chaos 30, 2050094 (2020)]. Taking the Stuart–Landau oscillators with the identical and nonidentical frequencies as examples, respectively, we find that the weighted average feedback is better than the previously proposed mean-field feedback in eliminating oscillation quenching with different coupling scenarios. Especially, when the weight is 0 or 1, that is, when a single oscillator is used as the feedback, the weighted average feedback is highly efficient in reviving oscillation. Our results provide a more convenient method to overcome these quenching states of coupled systems, and broaden the practical applications with respect to revoking rhythmic oscillations via external feedback in nature and real life. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing 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 article comments on the paper "Metallic Phase With long-Range Orientational Order and No Translational Symmetry," by D. Shechtman and coworkers. The paper discusses two basic principles of crystallography. It identifies sharp spots arrayed on a reciprocal lattice due to diffraction from periodic objects. The contributions of fluctations to the background diffuse intensity are noted.

In this paper, ideal boundary conditions have been created for recording instrument noises and their fluctuations at the level of pico-currents to describe quantitatively the voltammetric behavior of trace components of an electrochemical system and identify the best "ideal" device using voltammetric time series. The proposed mathematical model for the quantitative description of hidden patterns is formed by the data array itself, which includes hundreds of voltammograms (thousands of current values), and no single signals, as is conventionally accepted in the classical approaches of electroanalytical chemistry. This approach can be extended for correcting any other device and correlating its signals to the "ideal" level. The proposed methodology enables the selection of the best device among the supposed devices which opens new possibilities in the detection of the most sensitive instrument (all of them initially have passed through the calibration procedure!) for the "fine" detection of the trace signals. [ABSTRACT FROM AUTHOR]

A diagrammatic kinetic theory of density fluctuations in simple dense liquids at long times, described in Paper I, is applied to a high density Lennard-Jones liquid to calculate various equilibrium time correlation functions. The calculation starts from the general theory and makes two approximations. (1) The general diagrammatic expression for an irreducible memory kernel is approximated using a one-loop approximation. (2) The generalized Enskog projected propagator, which is required for the calculation, is approximated using a simple kinetic model for the hard sphere memory function. The coherent intermediate scattering function (CISF), the longitudinal current correlation function (LCCF), the transverse current correlation function (TCCF), the incoherent intermediate scattering function (IISF), and the incoherent longitudinal current correlation function are calculated and compared with simulation results for the Lennard-Jones liquid at high density. The approximate theoretical results are in good agreement with the simulation data for the IISF for all wave vectors studied and for the CISF and LCCF for large wave vector. The approximate results are in poor agreement with the simulation data for the CISF, LCCF, and TCCF for small wave vectors because these functions are strongly affected by hydrodynamic fluctuations at small wave vector that are not well described by the simple kinetic model used. The possible implications of this approach for the study of liquids are discussed. [ABSTRACT FROM AUTHOR]

The connection between quantum information and quantum gravity has captured the imagination of physicists. Recently, a broad new class of gravitational observables have been proposed to provide new possibilities for holographic complexity [1], which is an extension of volume in the Complexity=Volume proposal. In this paper, we investigate generalized volume-complexity for the 4-dimensional Reissner-Nordström-AdS black hole. These new gravitational observables satisfy the characteristic of the thermofield double state, i.e., they grow linearly in time on the late stage. We find that there are multiple extremal hypersurfaces anchored at a certain boundary time. In other words, for the same boundary time, more than one gravitational observable (generalized volume-complexity) can exist in the bulk. The size relationship of the gravitational observables on the two hypersurfaces changes over time. This will result in the substitution of the maximum extreme hypersurface which is dual to the complexity of the thermofield double state. We call the time when one hypersurface replaces another to become the largest extreme hypersurface the turning time τturning. That is, a hypersurface dual to the complexity of the thermofield double state defined on the boundary jumps from one branch to another. This discontinuous jump is highly reminiscent of a phase transition, and the turning time denotes the moment at which this phase transition occurs. Our findings propose a discontinuous variation in bulk physics that is dual to the complexity of the thermofield double state defined on the boundary. [ABSTRACT FROM AUTHOR]

The reduction of all the available photometry for the Cepheid CC Lyr has allowed its diagram spanning a time interval of 124 years to be constructed. The data obtained provide evidence for the existence of large random fluctuations in the period (). A formal fitting of the residuals has made it possible to estimate the rate of secular increase in the period, s yr . The pulsation stability test proposed by Lombard and Koen (1993) has confirmed that the increase in the period is real. [ABSTRACT FROM AUTHOR]

This paper presents a new multilevel cascaded-type dynamic voltage restorer (MCDVR) with a fault current-limiting function. This topology can operate in two operational modes: 1) a compensation mode for voltage fluctuations and unbalances and 2) short-circuit current-limiting mode. The current-limiting function of the MCDVR is performed by activating antiparallel thyristors during the short-circuit fault, and deactivating them during normal operation. The mathematical model of the MCDVR system is also established in this paper. The control scheme design and optimal parameter selection are outlined based on the detailed theoretical analysis of the converter. The transient states of the MCDVR in the compensation mode and current-limiting mode are also analyzed. Simulation results based on the PSCAD/EMTDC software, and experimental results on a laboratory setup help to validate the proposed topology and the theoretical analysis. [ABSTRACT FROM AUTHOR]

The existence of a general correlation between measured interharmonics and measured lamp flicker would be very significant. Present measurement and emission limitation standards for voltage fluctuations are based exclusively on the 60 W incandescent lamp's response to amplitude modulation of the power frequency. As use of incandescent lamps declines, the need increases to broaden voltage fluctuation quantification beyond lamp flicker. Amplitude modulation of the power frequency is mathematically equivalent to interharmonics summed with the power frequency. This, with the existence of international standards for measuring interharmonics, has suggested interharmonics as a possible basis for characterizing voltage fluctuations more broadly. Moreover, interharmonic measurements may be inherently extendable to quantify the effects of voltage fluctuations on devices other than incandescent lamps. However, any new method that offers advantages in broadening voltage fluctuation measurement must be capable of matching the results of present practices. Therefore, interharmonic measurements must first be demonstrated to be generally correlated to currently accepted flicker severity measurements. The correlation between these measurements is explored in this paper. It is concluded that by using the techniques in this paper, measured lamp flicker and measured interharmonics are correlated to a large extent for most industrial loads. [ABSTRACT FROM AUTHOR]

Summary: This paper presents photovoltaic (PV) systems modeling and fault analysis with solar energy fluctuation to discuss maximum fault current profiles. The modeled PV farm is arranged with series and parallel PV modules to offer 6.5 kV power. Two‐level 3‐phase voltage source inverter (VSI) and dc‐dc boost converter are used for all PV systems with LCL filter. A current control strategy using synchronous rotating frame method is implemented with park transformation approach. Average and aggregate models give inaccuracy, which this paper overcomes with accurate isolated single PV system, and PV‐dominated feeder. Pulse width modulation and sinusoidal pulse width modulation techniques are applied. Incremental conductance maximum power point tracking technique is used to extract PV maximum power. Phase locked loop technique for grid synchronization and proportional integral voltage control technique are also applied. Here, the maximum fault current corresponds to the maximum phase current at specified time. This simple and effective method is applied on PSCAD software simulations to collect the data. Discussions on obtained results showed short‐time irradiation fluctuation impacts on fault current profiles and argue on related aspects. The data comments and explanations to address analyzed protection challenges with PV penetration in distribution system are very promising. [ABSTRACT FROM AUTHOR]

In active distribution network, the random power output by wind/solar distributed generation may cause the stochastic fluctuation of demand side power, which will bring difficulties to power dispatching. In this paper, a method of restraining the demand side power fluctuation of active distribution network is proposed, in which a new power electronic device—electric spring—is applied by 0°/180° phase control strategy. Firstly, the basic principles of electric spring are introduced. Secondly, the reason for demand side power fluctuation of active distribution network is analyzed. After that, the 0°/180° phase control strategy of electric spring is proposed to restrain the demand side power fluctuation of active distribution network and the selection basis of noncritical loads is also obtained. The simulation results show that the method proposed in this paper is effective and the obtained selection basis of noncritical loads is reasonable. [ABSTRACT FROM AUTHOR]

Anisotropic spatial distribution data of refractive-index fluctuation in hypersonic turbulence are obtained based on the experimental images of hypersonic turbulence. Furthermore, taking re-entry turbulent plasma fluctuation into consideration, the variance of the refractive-index fluctuation in hypersonic plasma is calculated based on the Saha equation and the expression of refractive index in hypersonic plasma. On this basic, the anisotropic power-spectral model of hypersonic plasma turbulence is established by introducing the orientation factor to the modified von Karman spectrum. Finally, the mutual coherence function (MCF) and the angle-of-arrival fluctuations of electromagnetic (EM) waves propagation in hypersonic plasma turbulence are calculated. Results show that the angle-of-arrival fluctuations have obvious differences between the directions of vertical to turbulent plasma flow field and parallel to it. The various gradients of the electron density along the direction of vertical to turbulent plasma flow field are far greater than the parallel to it, which causes the horizontal scale is larger than perpendicular scale of plasma eddies. Therefore, when EM waves propagating through plasma turbulence, the refractive effect of plasma eddies show obvious anisotropy. The results of this paper can be used to analyze the EM waves propagation characteristics in hypersonic plasma turbulence. [ABSTRACT FROM PUBLISHER]

In this paper, the fluctuation properties of the number of energy levels (mode fluctuation) are studied in the mixed-type lemon billiards at high lying energies. The boundary of the lemon billiards is defined by the intersection of two circles of equal unit radius with the distance 2 B between the centers, as introduced by Heller and Tomsovic. In this paper, the case of two billiards, defined by B = 0.1953 , 0.083 , is studied. It is shown that the fluctuation of the number of energy levels follows the Gaussian distribution quite accurately, even though the relative fraction of the chaotic part of the phase space is only 0.28 and 0.16, respectively. The theoretical description of spectral fluctuations in the Berry–Robnik picture is discussed. Also, the (golden mean) integrable rectangular billiard is studied and an almost Gaussian distribution is obtained, in contrast to theory expectations. However, the variance as a function of energy, E, behaves as E , in agreement with the theoretical prediction by Steiner. [ABSTRACT FROM AUTHOR]

Quantum trajectory methods (QTMs) hold great promise as a potential means of obtaining dynamical insight and computational scaling similar to classical trajectory simulations but in an exact quantum dynamical context. To date, the development of QTMs has been stymied by the “node problem”—highly nonclassical and numerically unstable trajectories that arise when the wavepacket density |ψ|2 exhibits substantial interference oscillations. In a recent paper, however [B. Poirier, J. Chem. Phys. 128, 164115 (2008)], a “bipolar decomposition,” ψ=ψ++ψ-, was introduced for one-dimensional (1D) wavepacket dynamics calculations such that the component densities |ψ±|2 are slowly varying and otherwise interference-free, even when |ψ|2 itself is highly oscillatory. The bipolar approach is thus ideally suited to a QTM implementation, as is demonstrated explicitly in this paper. Two model 1D benchmark systems exhibiting substantial interference are considered—one with more “quantum” system parameters and the other more classical-like. For the latter, more challenging application, synthetic QTM results are obtained and found to be extremely accurate, as compared to a corresponding fixed-grid calculation. Ramifications of the bipolar QTM approach for the classical limit and also for multidimensional applications, are discussed. [ABSTRACT FROM AUTHOR]

We present a detailed analysis and discuss consequences of the strong correlations of the configurational parts of pressure and energy in their equilibrium fluctuations at fixed volume reported for simulations of several liquids in the previous paper [N. P. Bailey et al., J. Chem. Phys. 129, 184507 (2008)]. The analysis concentrates specifically on the single-component Lennard-Jones system. We demonstrate that the potential may be replaced, at fixed volume, by an effective power law but not simply because only short-distance encounters dominate the fluctuations. Indeed, contributions to the fluctuations are associated with the whole first peak of the radial distribution function, as we demonstrate by an eigenvector analysis of the spatially resolved covariance matrix. The reason the effective power law works so well depends crucially on going beyond single-pair effects and on the constraint of fixed volume. In particular, a better approximation to the potential includes a linear term, which contributes to the mean values of potential energy and virial, but little to their fluctuations, for density fluctuations which conserve volume. We also study in detail the zero temperature limit of the (classical) crystalline phase, where the correlation coefficient becomes very close, but not equal, to unity, in more than one dimension; in one dimension the limiting value is exactly unity. In the second half of the paper we consider four consequences of strong pressure-energy correlations: (1) analyzing experimental data for supercritical argon we find 96% correlation; (2) we discuss the particular significance acquired by the correlations for viscous van der Waals liquids approaching the glass transition: For strongly correlating viscous liquids knowledge of just one of the eight frequency-dependent thermoviscoelastic response functions basically implies knowledge of them all; (3) we reinterpret aging simulations of ortho-terphenyl carried out by Mossa et al. [Eur. Phys. J. B 30, 351 (2002)], showing their conclusions follow from the strongly correlating property; and (4) we briefly discuss the presence of the correlations (after appropriate time averaging) in model biomembranes, showing that significant correlations may be present even in quite complex systems. [ABSTRACT FROM AUTHOR]

The next generation of ultrahigh bypass ratio civil aero-engines promises notable engine cycle benefits. However, these benefits can be significantly eroded by a possible increase in nacelle weight and drag due to the typical larger fan diameters. More compact nacelles, with shorter intakes, may be required to enable a net reduction in aero-engine fuel burn. The aim of this paper is to assess the influence of the design style of short intakes on the unsteady interaction under crosswind conditions between fan and intake, with a focus on the separation onset and characteristics of the boundary layer within the intake. Three intake designs were assessed, and a hierarchical computational fluid dynamics (CFD) approach was used to determine and quantify primary aerodynamic interactions between the fan and the intake design. Similar to previous findings for a specific intake configuration, both intake flow unsteadiness and the unsteady upstream perturbations from the fan have a detrimental effect on the separation onset for the range of intake designs. The separation of the boundary layer within the intake was shock driven for the three different design styles. The simulations also quantified the unsteady intake flows with an emphasis on the spectral characteristics and engine-order signatures of the flow distortion. Overall, this work showed that is beneficial for the intake boundary layer to delay the diffusion closer to the fan and reduce the preshock Mach number to mitigate the adverse unsteady interaction between the fan and the shock. [ABSTRACT FROM AUTHOR]

In this paper, we studied the optomechanically induced transparency (OMIT) in a cavity optomechanical system containing a cubic nonlinear oscillator. In our system, a partially transparent, dielectric membrane was placed in the middle of the F-P cavity. Due to the partial transmission and reflective property of the membrane, the membrane was combined with both the mirrors on the left and right sides to form two cavities. When the system was driven by two coupling fields, we calculated the quantum fluctuation of the optomechanical system operators and showed the response of the cavity optomechanical system to the probe field. We found that the cubic nonlinearity led to a shift of the OMIT window, which moved towards a frequency less than the resonance frequency, and the absorption peak became significantly asymmetrical when OMIT appeared. The shift of the OMIT dip provided a method to detect the nonlinear effects of the system due to the existence of cubic anharmonic potential. [ABSTRACT FROM AUTHOR]

Non-equilibrium is dominant in geophysical and climate phenomena. However the study of non-equilibrium is much more difficult than equilibrium, and the relevance of probabilistic simplified models has been emphasized. Large deviation rates have been used recently in climate science. In this paper, after recalling progress during the last decades in understanding the role of large deviations in a class of non-equilibrium systems, we point out differences between equilibrium and non-equilibrium. For example, in non-equilibrium (a) large deviation rates may be extensive but not simply additive. (b) In non-equilibrium there are generically long-range space correlations, so large deviation rates are non-local. (c) Singularities in large deviation rates denote the existence of phase transitions often not possible in equilibrium. To exemplify, we shall refer to lattice gas models like the symmetric simple exclusion process and other models which are playing an important role in the understanding of non-equilibrium physics. The reasons why all this may be of interest in climate physics will be briefly indicated. [ABSTRACT FROM AUTHOR]