Asymmetric Behavior Research Articles

Peridynamic modeling of damage and non-shock ignition behavior of confined polymer bonded explosives under impact loading

A mechanical-thermal-chemical coupled peridynamic (PD) modeling for analyzing the damage and non-shock ignition behavior of polymer bonded explosives (PBXs) subject to impact loading has been presented. The friction and heat conduction and Arrenhenius law are embedded into the PD theory, ensuring that the simulation model is capable of capturing major features of dynamic damage response of PBX. A PD material model considering plasticity and the asymmetric behaviors of PBX under tensile and compressive loadings is proposed in this study. For a ring-shaped PBX 9501 sample confined by the steel structures, the simulation results indicate that the PBX 9501 in the regions towards the impact face and support face suffers from the serious damage. Meanwhile, the corresponding average temperatures in these two regions are also higher than their counterparts in other regions due to the more intense interaction between PBX 9501 and the steel confinement structures. The ignition time decreases with the increasing impact velocity within the range of 40–120 m s−1. The internal steel shell response is analyzed according to its velocity history within a representative box. It is found that the deformation process of internal steel shell is closely related to the complicated flow behaviors of PBX 9501.

Customers’ managerial expectations and suppliers’ asymmetric cost management

AbstractThis paper investigates how managers in the upstream firm (i.e., supplier) adjust their allocations of cost resources in response to managerial expectations of the downstream firms (i.e., customers) on the future demand and prospects. We conduct an empirical analysis to examine the impact of the tone of customers’ forward‐looking disclosures (FLDs) contained in the Management Discussion and Analysis section of 10‐K filings on suppliers’ asymmetric cost behaviors, characterizing costs decreasing less for sales fall than increasing for equivalent sales rise (i.e., “cost stickiness”). We show that the degree of suppliers’ asymmetric cost management is positively associated with their customers’ tone of FLDs. Moreover, such an association is stronger when the suppliers produce more unique products for their major customers. Our inferences remain robust after controlling for the strategic disclosure behavior of the customer firms, ruling out an alternative mechanism of suppliers’ own managerial expectations and managerial empire‐building incentives. Lastly, using a decision made by the U.S. Supreme Court in 2005 as a quasi‐natural experiment setting, we show that the effect of customers’ tone of FLDs on suppliers’ cost stickiness becomes stronger when FLDs are more informative. To the best of our knowledge, this paper is the first to introduce cost stickiness in the operations management context to capture management's operational decision intervention regarding resource allocation. We also contribute to information sharing literature by highlighting the importance of channels other than the traditional explicit information sharing channel in obtaining demand‐relevant information in supply chains.

Asymmetric Behaviour and Traffic Flow Characteristics of Expressway Merging Area in China

Drivers show different characteristics in traffic oscillations. These differences reflect the driver’s driving style, which is an important part of traffic uncertainty. This paper deeply explores the driving characteristics in asymmetric driving behaviour and its influence on traffic flow characteristics. The aim is to improve the understanding of safe driving. Continuous vehicle trajectories under various traffic flow conditions in an expressway merging area are obtained by aerial photography. Image processing technology is used to extract the basic parameters of traffic flow and vehicle operating characteristic data. Based on the measured data, the driver’s response mode is subdivided into multiple sub-modes. On the basis of this study, the types and distribution of traffic hysteresis and the impact of asymmetric behaviour on merging area capacity are further revealed. The results show that the response coefficient will increase for 58.72 % drivers during the process of experiencing oscillation disturbance to rebalance. The traffic hysteresis caused by driver’s asymmetric following behaviour in an expressway merging area is generally positive. This reduces the bottleneck outflow rate of the merging area by about 7 % on average. This study has important practical significance in analysing the formation mechanism of traffic congestion and adopting effective protective measures.

Asymmetric multifractal spectrum distribution based on detrending moving average cross-correlation analysis

This paper proposes the asymmetric multifractal spectrum distribution based on detrending moving average cross-correlation analysis (A-DMCA-MFSD) algorithm to calculate time-varying multifractal spectrum under different market trends. Numerical results of this algorithm applied to analyzing artificially generated data show superior performance in terms of accuracy and robustness. The algorithm is further applied to investigate auto-correlations of Bitcoin and Gold return series. Asymmetric behaviors of Bitcoin and Gold are obviously observed in small-scale fluctuations. In addition, Bitcoin series shows greater singularity strength than Gold in most of the time. Cross-correlations between Bitcoin and Gold are also studied utilizing A-DMCA-MFSD. Greater cross-correlation is observed during upward trends of Bitcoin (downward trends of Gold) than during downward trends (upward trends, respectively).

Energy security: the role of shale technology

Sustainable energy systems are sensitive to the countries’ energy portfolio decisions, shaping geopolitics and contributing to the global energy security (ES). Accordingly, this paper applies the “Markov regime-switching” method to explore the impact of “the North American shale technology” (NAST) on behavioral regimes of the US energy security measurements (ESM), e.g., diversity of primary energy demand ({mathrm{ESI}}_{mathrm{I}}), net energy import dependence ({mathrm{ESI}}_{mathrm{II}}), non-fossil fuel resource portfolio ({mathrm{ESI}}_{mathrm{III}}), and crude oil import dependency ({mathrm{ESI}}_{mathrm{IV}}). The findings confirm time-varying and asymmetric behavior of the US ESM before and after the NAST. Specifically, the overall interaction of substitution effect and scale effect of NAST strengthens the US energy systems through {mathrm{ESI}}_{mathrm{I}}, {mathrm{ESI}}_{mathrm{III}}, and {mathrm{ESI}}_{mathrm{IV}}, while {mathrm{ESI}}_{mathrm{II}} leads to higher risks of the US energy supply security. Consequently, the shale reserves development, diversification of primary energy demand and import supply, and advanced energy transport and trading policies, are suggested to overcome the barriers in achieving (i) availability, (ii) accessibility, (iii) affordability, and (iv) acceptability aspects of ES and vulnerability reduction of the US energy systems in respect of risk and resilience.

Cost stickiness and bank loan contracting

This study examines whether and, if so, how borrowers' asymmetric cost behavior (i.e., cost stickiness) is factored into the price and non-price terms of bank loan contracts. We provide strong and reliable evidence that ex-ante, the loan spread increases with cost stickiness after controlling for other known determinants of loan contract terms. Moreover, we find that the effect is more pronounced for borrowers with higher default risk and higher information risk. This is consistent with borrowers' asymmetric cost behavior increasing lenders' uncertainty about the liquidation value of assets, and hence, lenders need to be compensated ex-ante. Additionally, we conjecture that higher cost stickiness may increase the need for ex-post monitoring. Consistent with this conjecture, we find some evidence that lenders impose tighter non-price terms on firms with stickier costs. This study integrates cost stickiness research with the banking literature by showing that banks incorporate borrowers' asymmetric cost behavior into loan contracting terms.

The interest rate pass-through by loan size: Evidence for Mexico, 2011-2019

This paper measures the impact of changes in the central bank's reference rate on bank lending rates at both the aggregate level and by loan size. Our data come from the payroll and personal loan markets in Mexico for the period comprising 2011 to 2019. We use an autoregressive model with distributed lags, which allows for the possibility of asymmetric effects. The results show, among other findings, that the pass-through is small; it is not necessarily positive; asymmetric behaviour cannot be ruled out; and, its value depends on the loan size. These results imply that the effectiveness of monetary policy is weakened, in addition to the fact that the reaction of banks to changes in the target interest rate may have distributional implications. The originality of the paper lies in the grouping of interest rates by loan size and the use of a methodology that allows us to assess the existence of asymmetries. Its main shortcoming is the lack of data regarding the characteristics of the borrowers.

Crude Oil Price Shocks and Industrial Returns in Pakistan: An Examination through GARCH Based Dynamic Models

This paper attempts to examine the link between crude oil prices and industrial returns in Pakistan using daily data for the period of June-2008 to Jan-2021. Mean and volatility spillover is examined by using ARMA (1,1) GARCH (1,1)-M model. In addition, the timevarying nature of conditional correlation is determined by using DCC-GARCH models. Further, study has also investigated the impact of Covid-19 on the relationship between COP and INDR. Findings of the study provide strong evidence of volatility spillover from crude oil prices to Automobile Assemblers, Oil & Gas, Power Generation & Distribution and Refinery but only scarce evidence is found regarding mean spillover. DCC-GARCH model reveals the time-varying nature of conditional correlation between crude oil prices and all other industries. Moreover, the results also provide some evidence about asymmetric behavior in correlation among crude oil prices to Cement and Refinery.

High temperatures enhance the strength of multiple predator effects in a typical crab-clam system

Although marine heatwaves pose urgent threats to marine life, our understanding of how these events influence interactions between key species in marine ecosystems is still inadequate. Herein, we examined the behavioral mechanisms by which heat regulates multiple predator effects in different foraging systems that include Asian paddle crabs (Charybdis japonica) and swimming crabs (Portunus trituberculatus) by quantifying their predation and competition at two temperatures. Our results show that non-independent multiple predator effects occurred in the conspecific treatment of Asian paddle crabs and in the interspecific treatment, whereas independent multiple predator effects occurred in the conspecific treatment of swimming crabs. Asymmetrical behavior responses of these crabs to competition and heat triggered divergences in multiple predator effects. High temperatures increased the strength of multiple predator effects but did not alter their types. The reason is that heat negatively impacts predation by enhancing aggressive interactions, outweighing its direct positive effects on predation.

On the interplay between lipids and asymmetric dynamics of an NBS degenerate ABC transporter

Multidrug resistance-associated proteins are ABC C-family exporters. They are crucial in pharmacology as they transport various substrates across membranes. However, the role of the degenerate nucleotide-binding site (NBS) remains unclear likewise the interplay with the surrounding lipid environment. Here, we propose a dynamic and structural overview of MRP1 from ca. 110 μs molecular dynamics simulations. ATP binding to NBS1 is likely maintained along several transport cycles. Asymmetric NBD behaviour is ensured by lower signal transduction from NBD1 to the rest of the protein owing to the absence of ball-and-socket conformation between NBD1 and coupling helices. Even though surrounding lipids play an active role in the allosteric communication between the substrate-binding pocket and NBDs, our results suggest that lipid composition has a limited impact, mostly by affecting transport kinetics. We believe that our work can be extended to other degenerate NBS ABC proteins and provide hints for deciphering mechanistic differences among ABC transporters.

Activity and composition of the hyperactive comet 46P/Wirtanen during its close approach in 2018

Context. Hyperactive comets are a small group of comets whose activity is higher than expected. They seem to emit more water than would normally be expected given the size of their nucleus. Comet 46P/Wirtanen (hereafter, 46P) is among these objects of interest. Investigating its activity and composition evolution could provide clues about its origins and its formation region in the Solar nebulae. Aims. Given the exceptional close approach of comet 46P to the Earth in 2018, we aim to study the evolution of its activity and composition as a function of heliocentric distances before and after perihelion. Methods. We used both TRAPPIST telescopes to monitor the comet for almost a year with broad and narrow-band filters. We derived the production rates of five gaseous species (OH, NH, CN, C3, and C2) using a Haser model as well as the A(θ)fρ dust proxy parameter. The comet was also observed with the two optical high-resolution spectrographs UVES and ESPRESSO, mounted on the 8-m ESO VLT, to measure the isotopic ratios of C and N, along with the oxygen forbidden-line ratios and the NH2 ortho-to-para ratios. Results. Over nearly a year, we followed the rise and decline of the production rates of different species as well as the dust activity of 46P on both pre- and post-perihelion. Relative abundances with respect to CN and OH along the orbit of the comet show constant and symmetric abundance ratios and a typical coma composition. We determined the rotation period of the nucleus using high-cadence observations and long series of CN images on several nights. We obtained a value of (9.18±0.05) hours at perihelion. Using the high-resolution spectra of 46P coma, we derived C and N isotopic ratios of 100±20 and 150±30 as well as a green-to-red forbidden oxygen [OI] line ratio of 0.23±0.02. We measured a NH2 ortho-to-para ratio of 3.31 ±0.03 and derived an ammonia ratio of 1.19±0.03, corresponding to a spin temperature of 27±1 K. Conclusions. Narrow-band observations show that comet 46P is a hyperactive comet for which 40% of its nucleus surface is active. It has a typical composition, similar to other normal comets; however, an asymmetric behavior with respect to perihelion has been seen in its activity, which is typical of seasonal effects. Photometric measurements show no evidence for a change in the rotation period of the nucleus during this apparition. High-resolution spectra show that 46P has typical NH2 ortho-to-para, [OI] lines ratios, and C and N isotopic ratios.

Broadband solar‐driven water evaporator based on organic hybrid bandgap and bio‐mimetic interfaces

AbstractOwing to the lightweight, flexibility, and molecular diversity, organic photothermal materials are considered promising solar absorbent materials for water‐evaporating purification. Herein, we utilize the blend of two organic conjugated photothermal materials, PM6 and Y6, with broadband solar absorption from 350 to 1000 nm and high‐efficiency photothermal properties to fabricate a Janus water evaporator on cellulose paper. Similar to the asymmetric wetting behavior on the lotus leaf, the evaporator shows efficient water adhesion on the bottom surface and water repellency on the top surface for a desirable self‐floating capability and salt resistance. With a mass of only 0.5 mg per 3.14 cm2, the PM6:Y6 blend‐based water evaporator achieves 88.9% of solar thermal conversion efficiency (η) and 1.52 kg m−2 h−1 of solar water evaporation rate (m) under 1.0 kW m−2 solar irradiation. These properties are almost the best performance among purely organic water evaporators especially with such a premise of material saving. The concentrations of primary ions are significantly decreased by 4–6 orders after desalination, accompanied by excellent performance for wastewater treatment. This evaporator realizes a m of 1.21 kg m−2 h−1, a η of 75.7%, and a voltage of 61 mV under one sun irradiation by assembling with a thermoelectric equipment. This study demonstrates that the blending of PM6 and Y6 achieves photothermal synergism, which improves the photothermal property and water evaporation rate, providing a valuable prospect for their application in water purification and thermoelectric power generation.image

Motion control of hydraulic actuators with nonlinear friction compensation: Applied to variable valve systems of diesel engine

Friction force plays an important role in motion control systems. Research shows that friction force is strongly nonlinear in most applications. And the nonlinear friction force has great influence on control performance, especially in motion control systems of hydraulic actuators. To improve control performance, many model-based controllers have been developed. In the past years, LuGre model has been widely used in most hydraulic actuators. However, for systems with one-way seals whose friction force is asymmetric between instroke and outstroke stage, LuGre model is no longer suitable. The paper developed a friction force test bench and studied the transient friction force of a hydraulic actuator which includes one-way seals. Experiment results show that friction force at instroke stage is bigger than that of outstroke stage for the variable valve actuator. Based on the experiment results, a bristle direction hypothesis is proposed. The bristle of the friction surface is thought to have an initial direction. For actuators with two-way seals or without seals, the bristle is thought to be perpendicular to the friction surface. And for actuators with one-way seals, the angle between bristles and friction surface is not 90° anymore. To apply the bristle direction hypothesis to controllers, a bristle direction coefficient is introduced to LuGre model to explain asymmetric friction behaviors. The simulation results have good agreements with experiment results. Based on the improved LuGre model, a backstepping controller is developed to compensate the nonlinear friction force. The friction force and system matched uncertainty are estimated by an extended state observer. Finally, some comparative experiments are implemented to verify the advantages of the improved LuGre model. The experiment results show that the improved LuGre model can help to reduce the engine valve lift tracking errors. At outstroke stage (engine valve close), the maximum absolute errors can be reduced by 40.6% to 65.0%, and the mean absolute errors can be reduced by 21.2% to 59.4%.

Effect of Size on the Formation of Solid Solutions in Ag-Cu Nanoparticles.

Modern technologies stimulate the quest for multicomponent nanosized materials with improved properties, which are ultimately defined by the atomic arrangement and interphase interactions in the nanomaterial. Here, we present the results of the experimental study of the formation of solid solutions in Ag-Cu nanoparticles in a wide size and temperature range using in situ TEM techniques. The Ag-Cu nanoparticles with a eutectic ratio of components were formed on an amorphous carbon film by the physical vapor deposition technique. Electron diffraction, HAADF-STEM imaging, energy-dispersive X-ray spectroscopy, chemical element mapping, and electron energy loss spectral imaging were used for the characterization of mixing patterns and composition of phases in AgCu nanoparticles down to the atomic level. As a result, we constructed the solid-state part of the Ag-Cu phase diagram for nanoparticles with a size down to 5 nm. We found a highly asymmetric behavior of the solvus lines. Thus, the content of Cu in Ag gradually increased with a size reduction and reached the ultimate value for our configuration of 27 wt % Cu at a nanoparticle size below ∼8 nm. At the same time, no Cu-rich solid solution was found in two-phase AgCu nanoparticles, irrespective of the size and temperature. Moreover, a quasi-homogeneous solid solution was revealed in AgCu nanoparticles with a size smaller than 8 nm already at room temperature. A size dependence of the terminal temperature T term, which limits the existence of AgCu alloy nanoparticles in a vacuum, was constructed. Evaporation of the AgCu phase with the composition of 86 wt % Ag was observed at temperatures above T term. We show the crucial role of the mutual solubility of components on the type of atomic mixing pattern in AgCu nanoparticles. A gradual transition from a Janus-like to a homogeneous mixing pattern was observed in Ag-Cu nanoparticles (28 wt % Cu) with a decrease in their size.

Heterogeneous Catalytic and Non-Catalytic Supercritical Water Oxidation of Organic Pollutants in Industrial Wastewaters Effect of Operational Parameters

This work reports supercritical water oxidation (SCWO) of organic pollutants in industrial wastewater in the absence and presence of catalysts. To increase the efficiency of the oxidation process, the SCWO of organic compounds in industrial wastewater was performed in the presence of various iron- and manganese-containing heterogeneous catalysts (Fe-Ac, Fe-OH, and Mn-Al). The catalytic and non-catalytic SCWO of organic compounds in wastewater from PJSC “Nizhnekamskneftekhim”, generated from the epoxidation of propylene with ethylbenzene hydroperoxide in the process of producing propylene oxide and styrene (PO/SM), was performed. The effect of operational parameters (temperature, pressure, residence time, type of catalysts, oxygen excess ratio, etc.) on the efficiency of the process of oxidation of organic compounds in the wastewater was studied. SCWO was studied in a flow reactor with induction heating under different temperatures (between 673.15 and 873.15 K) and at a pressure of 22.5 MPa. The reaction time ranged from 1.8 to 4.83 min. Compressed air was used as an oxidizing agent (oxidant) with an oxidant ratio of two to four. A pseudo-first-order model expressed the kinetics of the SCWO processes, and the rate constants were evaluated. In the present work, in order to optimize the operation parameters of the SCWO process, we used the thermodynamic properties of near- and supercritical water by taking into account the asymmetric behavior of the liquid–vapor coexistence curve.

Comparing Water Transport Properties of Janus Membranes Fabricated from Copper Mesh and Foam Using a Femtosecond Laser

One of the important aspects of manipulating and controlling liquid transport is the design of membrane surfaces. Janus membranes with opposite wettability characteristics can be manufactured for efficient directional water transfer. In this work, two types of materials were used to fabricate membranes with an asymmetric wettability behavior: copper foam and copper mesh. One side of the membranes was treated by scanning with a femtosecond laser beam, as a result of which it was converted to a superhydrophilic state, while the untreated side remained hydrophobic. Both membranes demonstrated excellent properties of a water diode through which water droplets could easily pass from the hydrophobic side to the hydrophilic side, but not vice versa. This behavior was achieved by finding the optimal laser scanning speed. This type of Janus membrane has found applications in collecting water droplets from fog; therefore, the samples obtained were also tested in terms of harvesting micro-droplets. The Janus mesh-based structure has demonstrated a higher water collection efficiency (3.9 g/cm2 h) compared to the foam-based membrane (2.5 g/cm2 h). Since the fog-water conversion efficiency decreased over time (to 0.5 g/cm2 h in 2 weeks) due to the absorbance of organic pollutants, a coating of titanium oxide was applied to the laser-treated side of the Janus membranes. As a result, the effective function of the systems became distinctly long-lasting and was well maintained for at least 60 days. Moreover, the fabricated systems were protected from further degradation by simply placing them under sunlight for several hours. Our results prove to be useful in developing asymmetric hydrophobic-superhydrophilic membranes, which have potential applications in high-precision drop control and in harvesting water from arid environments.

Light‐Driven Folding Liquid Crystal Elastomer Catapult with Improved Morphing Velocity

As a typical behavior of releasing energy in a short time, catapulting is a way for organisms to adapt to complex and changeable environments, such as crossing terrain obstacles and spreading seeds. The essence of catapulting behavior is that plants and animals use their structural characteristics to control elastic strain energy locking, triggering, and releasing under external stimulation. At present, bistable or multistable structures are attractive for optimizing the system energy and improving the performance of liquid crystal elastomer (LCE) soft actuators. However, the overelaborate designation of such structures makes it a great challenge to achieve fast morphing LCE soft actuators. Here, a light‐driven azobenzene liquid crystal elastomer (azo‐LCE) soft actuator mimicking the catapulting behavior of fern sporangia is reported. 2D azo‐LCE monoliths are simply folded to construct V‐shaped structures as 3D catapults, which exhibit higher morphing velocity upon UV light, and the morphing velocity is related to the aspect ratio of films. Furthermore, asymmetric morphing behavior occurs by constructing localized UV irradiation conditions, which greatly improves the morphing velocity. It is envisioned that the origami‐inspired azo‐LCE catapults can be further designed as the throwing component in fast‐morphing soft robots for the remote delivery of microcargoes.

Modeling Income Data via New Parametric Quantile Regressions: Formulation, Computational Statistics, and Application

Income modeling is crucial in determining workers’ earnings and is an important research topic in labor economics. Traditional regressions based on normal distributions are statistical models widely applied. However, income data have an asymmetric behavior and are best modeled by non-normal distributions. The objective of this work is to propose parametric quantile regressions based on two asymmetric income distributions: Dagum and Singh–Maddala. The proposed quantile regression models are based on reparameterizations of the original distributions by inserting a quantile parameter. We present the reparameterizations, properties of the distributions, and the quantile regression models with their inferential aspects. We proceed with Monte Carlo simulation studies, considering the performance evaluation of the maximum likelihood estimation and an analysis of the empirical distribution of two types of residuals. The Monte Carlo results show that both models meet the expected outcomes. We apply the proposed quantile regression models to a household income data set provided by the National Institute of Statistics of Chile. We show that both proposed models have good performance in model fitting. Thus, we conclude that the obtained results favor the Singh–Maddala and Dagum quantile regression models for positive asymmetrically distributed data related to incomes. The economic implications of our investigation are discussed in the final section. Hence, our proposal can be a valuable addition to the tool-kit of applied statisticians and econometricians.

COVID-19 Pandemic & Financial Market Volatility; Evidence from GARCH Models

Across the globe, COVID-19 has disrupted the financial markets, making them more volatile. Thus, this paper examines the market volatility and asymmetric behavior of Bitcoin, EUR, S&P 500 index, Gold, Crude Oil, and Sugar during the COVID-19 pandemic. We applied the GARCH (1, 1), GJR-GARCH (1, 1), and EGARCH (1, 1) econometric models on the daily time series returns data ranging from 27 November 2018 to 15 June 2021. The empirical findings show a high level of volatility persistence in all the financial markets during the COVID-19 pandemic. Moreover, the Crude Oil and S&P 500 index shows significant positive asymmetric behavior during the pandemic. Apart from this, the results also reveal that EGARCH is the most appropriate model to capture the volatilities of the financial markets before the COVID-19 pandemic, whereas during the COVID-19 period and for the whole period, each GARCH family evenly models the volatile behavior of the six financial markets. This study provides financial investors and policymakers with useful insight into adopting effective strategies for constructing portfolios during crises in the future.

Existence and multiplicity of solutions for resonant-superlinear problems

ABSTRACT We consider a semilinear Dirichlet problem with a reaction which exhibits an asymmetric behaviour as (it is superlinear as and resonant as ). Using variational tools from the critical point theory, together with truncation and comparison techniques and critical groups, we prove two multiplicity theorems producing two and three nontrivial solutions. Also we show that the problem can not have negative solutions.