Second-order Effects Research Articles

Circular steel tube-confined ultra-high performance concrete beam-column: Database, modeling, and design

The fiber beam element (FBE) model is widely used to simulate and predict the nonlinear behavior of structures owing to its simplicity and high computational efficiency. The accuracy of the FBE simulation of ultra-high-performance concrete (UHPC) filled steel tubular (UHPCFST) members is mainly dependent on the input materials and interactions between the steel tubes and concrete, such as second-order effect, yielding of steel tubes and passive confinement effect to the UHPC. This work proposes uniaxial effective stress-strain models of UHPC confined by circular steel tubes based on existing experimental data that are integrated into the FBE model to predict the nonlinear behavior of UHPCFST members. The robustness and reliability of the proposed material models are comprehensively verified against a database encompassing a wide range of materials and geometric parameters under different loading conditions (monotonic and cyclic loading). Furthermore, the application of existing design codes for computing ultimate bending strengths is assessed using an established experimental database. Finally, the ultimate bending strengths of circular UHPCFSTs are calculated using a novel and simplified N–M interaction equation. It is demonstrated that the developed material models could predict the nonlinear behaviors of circular UHPCFST members with good satisfaction, and that current design codes, to some extent, underestimate the ultimate bending strengths of circular UHPCFST columns, the proposed practical method in this study is highly accurate, with a mean value of 1.00.

Overcharging an accelerating Reissner-Nordström-anti-de Sitter black hole with test field and particle

Accelerating black holes have been widely studied in the context of black hole thermodynamics, holographic gravity theories, and in the description of black holes at the center of galaxies. As a fundamental assumption to ensure spacetime causality, we investigate the weak cosmic censorship conjecture (WCCC) in the accelerating Reissner-Nordström-Anti-de Sitter (RN-AdS) spacetime through the scattering of a charged field and the absorption of a charged particle. For the scattering of a charged scalar field, both near-extremal and extremal accelerating RN-AdS black holes cannot be overcharged, thereby upholding the validity of the WCCC. In the case of the absorption of a test charged particle, the results demonstrate that the event horizon of the extremal accelerating RN-AdS black hole cannot be destroyed, while the event horizon of the near-extremal black hole can be overcharged if the test particle satisfies certain conditions. The above results suggest that, in the case of test particles, second-order effects like self-force and self-energy should be further considered.

Crustal stress pattern at Mt. Etna volcano

Stress fields may exhibit variegated patterns, especially in volcanic areas where several processes superimpose their effects in space and time. The comprehension of such patterns may not be straightforward to investigate. This work investigates the pattern of the crustal stress in the area of Mt. Etna Volcano (Sicily, Italy). This has been possible through a collection of more than 800 stress indicators derived from seismological and volcanological/geological information. In particular, the type of collected data allows to consider, for the first time in this area, two different temporal steps in the evolution of Etna volcano: the present-day and the previous volcanic phase at 15 ka. Results indicate a transition between a background shallow NW-SE tensional regime and a deep SW-NE compressional one that occurs between 6 and 16 km depth and which well fits with the present-day geodynamic framework of the area. The occurrence of small-scale lateral variations is interpreted as the second-order effect of the structures of the active front buried beneath the volcano, to the volcano loading, and to the feeding system. The temporal variations in the area surrounding the volcano suggest a major rearrangement of the background stress field evidenced by the swap between minimum and maximum horizontal stress directions. Conversely, during the same period, the stress pattern in the exact correspondence of the volcanic edifice showed to be stable and with a radial arrangement. Such coherence would support the literature which suggests a long-term inflation process started at least 15 kyr ago.

Resonant x-ray difference frequency generation

Resonantly enhanced x-ray difference-frequency generation (re-XDFG) is a second-order nonlinear effect that involves illuminating a molecule with two-color x-ray pulses with photon energies Ω1 and Ω2. The energy difference is tuned to match an x-ray absorption edge of an atom in the molecule. We have numerically studied the re-XDFG effect considering different individual molecules in the gas phase using density functional theory calculations and have verified the non-centrosymmetric character of the target transitions. Two-level molecular systems with permanent dipoles are evaluated for the description of re-XDFG taking into account different two-color input pulse geometries. This innovative nonlinear x-ray methodology offers a means to measure the K-edge NEXAFS spectrum of light elements, such as carbon, nitrogen, or oxygen, in dense media using non-resonant x-rays. It can also be used to investigate chemical material dynamics that are inaccessible by linear spectroscopy. These findings enable the combination of atomic-scale structure with chemical specificity and the selective and local access to x-ray excitations using hard x-ray pulses.

Electron impact triple differential cross sections of Xe atoms for coplanar to perpendicular plane single ionisation at 60 eV, 80 eV and 100 eV above ionisation

The evolution of the triple differential cross section (TDCS) for the electron impact ionisation of xenon atoms is reported for the variation of momentum of the projectile electron from a coplanar geometry to a perpendicular plane through intermediate angles with the detection plane. The TDCSs have been calculated for the Xe atoms at 60 eV, 80 eV and 100 eV above the ionisation potential. We have calculated the TDCS using distorted wave Born approximation, utilising both the first and second Born terms. Effects of target polarisation and post-collision interaction have also been included in the complete description of the collision dynamics. The TDCS results are compared with recent measurements by Patel et al (2022 Phys. Rev. A 105 032818) showing a dependence between the TDCS and the scattering geometry and kinematics of the collision. Second-order effects have been found significant, particularly in the description of perpendicular plane ionisation at a low energy and the effect of target polarisation has been found important in describing the coplanar ionisation of the xenon target. With an overall good agreement with the recent measurements, there are points of disagreement which are the motivation for further theoretical effort in the near future, as the present attempt is the first of its kind to analyse these measurements.

A complete analysis of the link uncertainty budget for pulsed laser time transfer on China space station

High-precision Time-Frequency Rack (HTFR) mission, a part of experiment module II of the China Space Station (CSS), was equipped with a Sr optical clock, H-maser, and laser-cooled microwave clock. To compare time and frequency across widely separated clocks, a microwave link, and a pulsed laser link were both established, which probably enables new possibilities for fundamental science, geodesy, and metrology. Based on the existing relativistic theory for time and frequency transfer, we derive a relativistic model of satellite-ground laser time transfer on CSS (CLT), which can be of direct use in CLT data processing. In addition to first and second-order Sagnac effects, it also includes relativistic rate shifts, atmospheric refraction, and turbulence, laser retroreflector array (LRA) range correction, and position correction between detector and reflector, satisfying the stability evaluation of CSS atomic clocks with fractional frequency stability of 3 × 10−17/10000 s. Additionally, we numerically investigate the link error magnitude and use Monte Carlo simulations to assess the impact of correcting for link errors on the stability of the CLT, taking into account the CSS orbit and attitude determinations as well as the CLT payload calibration parameters. It is shown that the CLT link can be considered to reach a TDEV of approximately 0.1 ps/300 s while meeting the CSS design objectives. The primary factors that influence the stability of the CLT are the position correction between detector and reflector, LRA range correction, and the coupling relation of these two error distributions.

Some characteristic properties of the solutions in the three-phase-lag heat conduction

In this paper we consider the three-phase-lag model of heat conduction that involves second-order effects in phase lag of the heat flux vector. This model leads to a fourth-order in time equation of Moore–Gibson–Thompson type. We use the thermodynamic restrictions derived from the compatibility of the constitutive equation with the Second Law of Thermodynamics to study the properties of the solutions of the initial boundary value problems associated with the model in concern. In this connection we establish a series of well-posedness results concerning the related solutions like: uniqueness, continuous data dependence, exponentially stability or domain of influence. Furthermore, based on the thermodynamic restrictions, we show that the thermal model in question admits damped in time propagating waves as well as exponentially decaying standing modes. We also show that when the thermodynamic restrictions are not fulfilled, then wave solutions appear that cause the energy blows up as time goes to infinity.

Proactive digital workplace transformation: Unpacking identity change mechanisms in remote-first organisations

Digital transformation fundamentally changes the way individuals conduct work in organisations. In accordance with this statement, prevalent literature understands digital workplace transformation as a second-order effect of implementing new information technology to increase organisational effectiveness or reach other strategic goals. This paper, in contrast, provides empirical evidence from two remote-first organisations that undergo a proactive rather than reactive digital workplace transformation. The analysis of these cases suggests that new ways of working can be the consequence of an identity change that is a precondition for introducing new information technology rather than its outcome. The resulting process model contributes a competing argument to the existing debate in digital transformation literature. Instead of issuing digital workplace transformation as a deliverable of technological progress and strategic goals, this paper supports a notion of digital workplace transformation that serves a desired identity based on work preferences.

ASD and LRFD: Reliability comparison for designs subjected to wind loads

Current design practice in the United States allows engineers to use either Allowable Strength Design (ASD) or Load and Resistance Factor Design (LRFD) method, under the assumption that both methods provide similar levels of economy (available design strengths) and safety (probabilities of failure and reliability indices) regardless of the design conditions. Recent studies have demonstrated that significant differences in economy can arise between ASD- and LRFD-based designs subjected to combinations of gravity and wind loads, suggesting inconsistencies between the safety levels. This study investigates the safety levels provided by the ASD and LRFD methods for such design cases. The safety levels were estimated using a formal reliability analysis with consideration of geometrically non-linear second-order effects. The reliability analysis was performed using Monte Carlo simulations with appropriate probability distributions for the random variables associated with both resistance and loads. The findings of this study indicate that generally accepted uniformity of reliabilities achieved by the ASD and LRFD methods does not hold for design cases governed by wind loads. The safety levels achieved by using the ASD method are less consistent than those achieved by using the LRFD method. The use of the ASD method generally entails the acceptance of failure risks many times greater than for those of the LRFD method, and target safety levels lower than those stipulated by the ASCE 7 Standard. These results highlight the need for a reevaluation of the current design practices to ensure that the required target levels of structural safety are consistently met.

Nonlinear Ringdown at the Black Hole Horizon.

The gravitational waves emitted by a perturbed black hole ringing down are well described by damped sinusoids, whose frequencies are those of quasinormal modes. Typically, first-order black hole perturbation theory is used to calculate these frequencies. Recently, it was shown that second-order effects are necessary in binary black hole merger simulations to model the gravitational-wave signal observed by a distant observer. Here, we show that the horizon of a newly formed black hole after the head-on collision of two black holes also shows evidence of nonlinear modes. Specifically, we identify one quadratic mode for the l=2 shear data, and two quadratic ones for the l=4, 6 data in simulations with varying mass ratio and boost parameter. The quadratic mode amplitudes display a quadratic relationship with the amplitudes of the linear modes that generate them.

Second-order effects in horizontally loaded reinforced concrete columns

Abstract This paper deals with the second-order effects in horizontally loaded reinforced concrete columns. The current standard approach according to Eurocode 2 is the starting point for the considerations. Simplified methods that take into account the secondary effects, that is, the nominal stiffness method and the nominal curvature method, and their limitations are discussed. Most attention is devoted to the general method. As only general guidelines for this method can be found in the literature on the subject, the author presents his own original approach to calculations done using this method. Exemplary analyses for the corbel columns of high bay racked warehouses are made. Columns of different lengths are analyzed. The calculations show the overestimates introduced by the simplified methods and the benefits stemming from the use of the general method, especially in the case of quite slender columns.

Približni proračun kružnih AB stupova uz pomoć nomograma

Calculating the reinforcement of circular reinforced concrete (RC) columns involves not only the dual nonlinearity of the geometry and material but also the nonlinearity of the section width. Accurate solutions require iterative calculations. To develop the calculation method manually, the model column method was proposed to compute the second-order effect of the columns, and the strain method was used to calculate the ultimate strength of the sections analytically. The nomograms required to calculate the reinforcing steel content of the columns without iterations were obtained. The nomogram for calculating the section bearing capacity and reinforcing steel has three parameters (axial force, bending moment, and mechanical ratio of the reinforcing steel). Further, the nomogram for calculating the column bearing capacity and reinforcing steel has five parameters (axial force, bending moment, curvature, slenderness ratio, and mechanical ratio of the reinforcing steel), and the relationship between the five parameters can be expressed in a plan, which makes the application convenient. Finally, the calculation results of the nomograph were compared with those of the existing approximate calculation formulas and exact numerical methods, and the accuracy of the nomograms was verified.

Research on particle noise based on second-order effect

The development of integrated circuits has gone through several stages, from the invention of transistors to the emergence of very large scale integrated circuits and system level integrated circuits. Now, the size of integrated circuits enters the nanometer level, and short-channel shot noise becomes an important issue. Short-channel shot noise increases due to factors such as device size reduction and scattering during channel formation. It has a serious impact on the performance, power consumption and reliability of integrated circuits. The formation mechanism of short channel shot noise can be explained from two aspects: one is due to the existence of thermal noise inside the channel, and the other is due to the noise caused by the shot. As the device size decreases, the channel thermal noise gradually changes into shot noise and becomes one of the main noise sources. Aiming at the noise generation mechanism, this paper proposes several methods to solve the short-channel shot noise. Through the research of short-channel shot noise and the exploration of solutions, the impact of shot noise on IC performance can be better understood and dealt with, and the development and innovation of IC technology can be promoted.

The influence of second-order effect on circuit design

The purpose of this paper is to deeply study and understand the influence of second-order effects (channel length modulation effect, bulk effect, subthreshold conductivity short channel effect) on the performance of electronic devices and circuits, and to propose effective methods and techniques to reduce their negative effects. The author will pay attention to the mechanism and characteristics of channel length modulation effect, bulk effect, subthreshold conductivity and short channel effect, and the key factors leading to their changes. Through theoretical analysis, process inversion and simulation, various effective suppression or compensation strategies are explored to improve the performance of electronic devices and circuits and enhance their reliability and stability. Through the in-depth study of the second-order effect, readers can better understand and solve the influence brought by the second-order effect.

Construction of mixed-level screening designs using Hadamard matrices

Modern experiments typically involve a very large number of variables. Screening designs allow experimenters to identify active factors in a minimum number of trials. To save costs, only low-level factorial designs are considered for screening experiments, especially two- and three-level designs. In this article, we provide a systematic method to construct screening designs that contain both two- and three-level factors based on Hadamard matrices with the fold-over structure. The proposed designs have good performance in terms of D-optimal and A-optimal criteria, and the estimates of the main effects are unbiased by the second-order effects, making them very suitable for screening experiments. Besides, some theoretical results on D- and A-optimality are obtained as a by-product.

Cold-formed steel strength predictions for torsion and bending–torsion interaction

Locally slender cross-section members, such as cold-formed steel open sections, are susceptible to significant twisting and high warping torsion stresses. Torsion considerations are complicated by whether it is derived as a first-order effect from loading or a second-order effect from instability. Previous direct torsion experiments on lipped Cee sections have shown significant inelastic reserve. Furthermore, the current design for combined bending–torsion interaction has limitations, including only considering the first yield and ignoring the cross-section slenderness in torsion. Two parametric studies were conducted to predict both the torsion capacity and the combined bending–torsion interaction in locally slender cross-sections. Shell finite element analysis of lipped Cee and Zee sections for both the torsion only and the combined bending–torsion cases were created using a validated model. For the torsion-only study, various cross-section geometries, steel grades, and member lengths covering the range of practically expected torsional slenderness were investigated. A set of bimoment parameters, including yield, buckling, and plastic bimoments, were calculated and the ultimate bimoment was determined by shell finite element collapse analyses. A simple uniform equation predicting the bimoment capacity was adopted and two bimoment strength curves are proposed for local and distortional buckling-controlled cases respectively. For the combined bending–torsion case, various practical cross-sections and bracing conditions were investigated with various ratios of applied torsion and bending. Shell finite element buckling and collapse analyses were performed to determine the critical and ultimate moments and bimoments. It was found that the current AISI standard is conservative under most scenarios. Updated torsion–bending interaction equations incorporating bimoment and bending moments are proposed. The interaction equations are dependent on the cross-section, the direction of the applied torsion, and the bracing condition.

Stability of Steel Columns with Concrete-Filled Thin-Walled Rectangular Profiles

This paper provides a numerical and experimental analysis of global stability of axially compressed columns made of thin-walled rectangular concrete-filled steel tubes (CFSTs), with the consideration of initial geometric imperfections. The presented work introduces the theory of stability and strength of composite structural members subjected to axial compressive force. Moreover, a numerical calculation method for the determination of column resistance under axial load is presented, taking into account the influence of second-order effects that are considered in the European standard for the design of such members. This paper also presents the method of creating 3D models using the ABAQUS software, numerical analysis, and comparison of the obtained numerical results with experimental tests. In addition to the actual boundary and load conditions, the real properties of the used materials were also taken into account during the creation of 3D models. The actual properties of the used materials were obtained experimentally. Based on the obtained results and their comparison, several new findings and proven facts about the design and assessment of axially compressed columns made of thin-walled rectangular steel tubes filled with concrete are presented in the conclusions of the paper.

Toward a Stakeholder View of Upper Echelons: A Framework Synthesis Review and Future Research Agenda

The growing literature at the intersection of executives’ characteristics and stakeholders’ evaluations argues that executives’ characteristics not only have “first-order effects” on their organizations’ actions and outcomes, as in upper echelons theorizing, but also give rise to “second-order effects” or “opportunity structures,” whereby stakeholders evaluate and react to focal executives’ organizations based on those characteristics. Despite many insights from the burgeoning literature on the second-order effects of executives’ characteristics on stakeholders’ evaluations and reactions, the literature lacks a comprehensive framework with core tenets by which stakeholders form evaluations of executives’ characteristics that drive their actions (or, reactions, as it were) based on such characteristics and the ensuing outcomes. In turn, knowledge from the proliferating literature on how stakeholders react on the basis of their evaluations of referent organizations’ executives’ characteristics is fragmented, consisting of a series of disconnected findings and attendant insights scattered across various theoretical and topical domains. We conducted a framework synthesis of the literature to iteratively derive a conceptual framework from extant research—which we call the stakeholder view of upper echelons—that synthesizes knowledge at the intersection of executives’ characteristics and stakeholders’ reactions around this framework. In doing so, we provide the foundation for future research to help extend knowledge in this important domain. We identify several avenues that are important for future work to address and provide practical implications from our framework.

Stochastic dynamics of multi-waterfall hybrid inflation and formation of primordial black holes

We show that a hybrid inflation model with multiple waterfall fields can result in the formation of primordial black holes (PBHs) with an astrophysical size, by using an advanced algorithm to follow the stochastic dynamics of the waterfall fields. This is in contrast to the case with a single waterfall field, where the wavelength of density perturbations is usually too short to form PBHs of the astrophysical scale (or otherwise PBHs are overproduced and the model is ruled out) unless the inflaton potential is tuned. In particular, we demonstrate that PBHs with masses of order 1020 g can form after hybrid inflation consistently with other cosmological observations if the number of waterfall fields is about 5 for the case of instantaneous reheating. Observable gravitational waves are produced from the second-order effect of large curvature perturbations as well as from the dynamics of texture or global defects that form after the waterfall phase transition.

Nonreciprocal Transport and Optical Phenomena in Quantum Materials

In noncentrosymmetric materials, the responses (for example, electrical and optical) generally depend on the direction of the external stimuli, called nonreciprocal phenomena. In quantum materials, these nonreciprocal responses are governed by the quantum geometric properties and symmetries of the electronic states. In particular, spatial inversion ([Formula: see text]) and time-reversal ([Formula: see text]) symmetries play crucial roles, which are also relevant to the geometric Berry phase. Here, we give a comprehensive review of the nonreciprocal transport and optical responses including ( a) the magnetochiral anisotropy, i.e., the nonlinear resistivity with respect to the electric field, in semiconductors and metals, ( b) the nonreciprocal transport in superconductors such as the nonreciprocal paraconductivity and the superconducting diode effect in bulk and Josephson junctions, and ( c) the second-order nonlinear optical effects in the electric field of light, including the geometric shift current in nonmagnetic systems, magnetic systems, and superconductors.