State Behavior Research Articles

A value-of-information-based optimal sensor placement design framework for cost-effective structural health monitoring (with application to miter gate monitoring)

Structural health monitoring (SHM) involves collecting information to assess the health of a structure, typically to guide risk-informed maintenance decision-making or predict limit state behavior throughout its lifespan. Although the value of information (VoI) obtained from an SHM system can facilitate improved decision-making, it is important to estimate its overall utility by considering the costs involved in designing, developing, installing, maintaining, and operating the system. A feasible SHM system provides greater expected returns resulting from data-informed lifecycle management decisions than the cost of the SHM system design, fabrication, deployment, operation, and maintenance. That is, since data acquisition is a precursor to data-informed decision-making, the design of an SHM system governs its feasibility. Such cost-benefit analyses are a current topic of research in the SHM community. One approach that has been proposed for these analyses is a preposterior decision analysis using the VoI metric. In this paper, we propose a sensor optimization framework that maximizes the VoI over the structure’s lifecycle, constrained by a pre-decided maintenance policy. We use two different VoI metrics: the traditional expected VoI and a gambling-theory-inspired normalized expected-savings-to-investmentrisk ratio. We introduce three time-normalized, unitless VoI metrics that are valuable for evaluating the performance of an SHM design over an extended period. Furthermore, we consider the effect of different risk profiles on the overall optimal sensor design, recognizing that the cost of decision-making depends on the utility and risk perception of the decision-maker. We conduct a detailed analysis on the marginal utility gain of gathered information as we add more sensors, observing the utility to diminish in line with the law of diminishing returns as the information content increases. This framework is applied to the design of an SHM system used for monitoring miter gates.

Exploring Ultrafast Carrier Dynamics in Photoelectrochemical Water Splitting Using Transient Absorption Spectroscopy

AbstractHydrogen fuel produced from water splitting using sunlight remains one of the cleanest and most sustainable energy sources. However, photoelectrochemical hydrogen production faces several challenges, including poor sunlight absorption, deficient charge carrier lifetime and transfer rates, and very sluggish kinetics of the water oxidation half‐reaction. To address these challenges, researchers have concentrated on enhancing the efficiency of photoelectrochemical water splitting. A critical factor in this enhancement is a deeper understanding of the fundamental processes involved in photoabsorption and the subsequent oxidation evolution reaction. The advent of ultrafast lasers has enabled the detailed tracking of charge carriers within materials after sunlight absorption, including their separation and migration to the surface for water oxidation. Ultrafast transient absorption spectroscopy is a powerful technique that allows real‐time observation of the behavior of excited states and charge carriers on femtosecond to nanosecond timescales. Recent studies utilizing ultrafast transient absorption spectroscopy are explored to investigate the dynamics of charge carriers in photoelectrochemical water splitting, providing insights into the mechanisms that lead to the design of enhanced photoanodes with improved efficiency.

Ultrafast reconfigurable direct charge trapping devices based on few-layer MoS2

Abstract Charge trapping devices incorporating 2D materials and high-κ dielectrics have emerged as promising candidates for compact, multifunctional memory devices compatible with silicon-based manufacturing processes. However, traditional charge trapping devices encounter bottlenecks including complex device structure and low operation speed. Here, we demonstrate an ultrafast reconfigurable direct charge trapping device utilizing only a 30 nm-thick Al2O3 trapping layer with a MoS2 channel, where charge traps reside within the Al2O3 bulk confirmed by transfer curves with different gate-voltage sweeping rates and photoluminescence (PL) spectra. The direct charging tapping device shows exceptional memory performance in both three-terminal and two-terminal operation modes characterized by ultrafast three-terminal operation speed (≈300 ns), an extremely low OFF current of 10-14 A, a high ON/OFF current ratio of up to 107, and stable retention and endurance properties. Furthermore, the device with a simple symmetrical structure exhibits VD polarity-dependent reverse rectification behavior in the high resistance state (HRS), with a rectification ratio of 105. Additionally, utilizing the synergistic modulation of the conductance of the MoS2 channel by VD and VG, it achieves gate-tunable reverse rectifier and ternary logic capabilities.

Should Zoo Food Be Chopped for Ruffed Lemurs? It's Not so Black and White.

Whole food diets in zoos have the potential to reduce microbial contamination and keeper preparation time, whilst also reducing food nutrient breakdown. Given these benefits, it is important to determine whether there is any value in chopping up food. Lemurs (Family Lemuridae) are common in zoos, with over 7500 individuals housed globally. Given their regular occurrence in collections, plus the high incidence of frugivory, lemurs are an excellent taxon to investigate food presentation effects on behavior. A study was undertaken at Beale Wildlife Park on a group of four black-and-white ruffed lemurs (Varecia variegata) to investigate food presentation and preference. Animal behavior was recorded using instantaneous focal sampling at 60 s intervals to record state behaviors and continuous focal sampling to record event behaviors in 1-h sessions. Food preference was done by recording the first three food items consumed by individual lemurs. Overall, food manipulation was significantly increased during whole food presentation allowing the lemurs to display species-specific behaviors. Feeding and foraging were highest during very chopped food condition and inactivity was lowest in very chopped food presentation. When looking at aggressive interactions, there was an increase in stealing and locomotion with food during whole food presentation, whereas biting and startle were lower. Proving high-value food items chopped and low-value food items whole could reduce aggression while reduce aggression seen over high-value food items. For food preference, sweet potato was consistently in the top three food items for all lemurs, with beetroot being the second most-picked food item. This suggests that these individuals have a strong preference for food items high in carbohydrates. Keeper preparation time was significantly reduced during whole food preparation. Further research assessing a wider range of zoo-housed species would be beneficial to assess the effects of food presentation on behavior.

Engineering of hyperentangled complex quantum networks

Abstract We propose a novel scheme to engineer the atomic hyperentangled cluster and ring graph states invoking cavity-QED technique for applicative relevance to quantum biology and quantum communications utilizing the complex quantum networks. These states are engineered using both external quantized momenta states and energy levels of neutral atoms under off-resonant and resonant Atomic Bragg Diffraction (ABD) technique. The study of dynamical capacity and potential efficiency have certainly enhanced the range of usefulness of these states. In order to assess the operational behavior of such states when subjected to a realistic noise environment has also been simulated, demonstrating long enough sustainability of the proposed states. Moreover, experimental feasibility of the proposed scheme has also been elucidated under the prevailing cavity-QED research scenario.

Strategic States: The Congressional Roots of Federal Grant Applications

Abstract While a large body of research explores the federal-level influences over distributive politics decisions, very little attention has been given to the active role state and local governments play in the geographic distribution of federal funds. Before presidents, legislators, and agency leaders can influence the selection of federal grants, state and local governments must expend time and resources to submit grant proposals. We focus on grant applications as our unit of analysis and advance a theory that congressional representation influences the grant application behavior of state and local governments. We analyze US Department of Transportation grant applications and awards from 2009 to 2022 and find evidence that congressional representation meaningfully influences state-level grant application behavior. States apply more aggressively for federal transportation grants when represented by senators in the Senate majority party, and states apply more efficiently for grants when represented by a senator holding an advantageous committee leadership post.

Nonlinear Adaptive Neural Control of Power Converter‐Driven DC Motor System: Design and Experimental Validation

ABSTRACTThis article presents an intelligent adaptive neural control scheme to track the output speed trajectory in power converter‐driven DC motor system. The proposed technique integrates an adaptive polynomial‐neural network with a backstepping strategy to yield a robust control system for output tracking in DC motor. Such a unification of online neural network‐based estimation and adaptive control, results in effective regulation of the output across a wide load torque uncertainties, besides yielding a promising transient and steady‐state performance. The stability of the entire closed‐loop system is ensured through Lyapunov stability criterion. The efficacy of the proposed strategy is revealed through an extensive experimental investigation under various operating points during start‐up, step‐reference tracking, and external step‐load torque disturbances. The real‐time experimentation is conducted on a laboratory prototype of power converter‐driven DC motor of 200 W, using dspace DS1104 control board with MPC8240 processor. The results obtained confirm an improvement in the transient response of the output speed by significantly reducing the settling time to and yielding a steady state behavior with no peak over/undershoots during load disturbances, in contrast to other similar works presented in the literature intended for same the application.

Elevating Nonlinear Optical Response through d-electron Modulation in Metal-Organic Frameworks.

Electronic structure and excited state behavior is of pronounced influence on regulation of nonlinear optical (NLO) response. Herein, a serials of transition metal ions bearing different d-electron numbers were in situ coordinated within porphyrinic metal-organic frameworks (MOFs), creating NLO-responsive M-metal (metal = Fe, Co, Ni, Cu, and Zn) frameworks. It demonstrated that the NLO properties can be optimized with the increased occupancy of the d-shell, which enhances the degree of delocalization. Specifically, the full-filled (d10) electron configuration of Zn2+ stabilizes the electronic structure, combination with π-π* local excitation character of M-Zn, promoting charge transfer process and resulting in outstanding NLO properties. Moreover, parameters related to the nonlinear process (β, n2, Imχ(3), Reχ(3) and χ(3)) of M-Zn are calculated to be higher than those of other materials, consistent with theoretical calculations. This work paves the way for NLO modulation based on electronic analysis and provides a promising approach for constructing high-performance NLO materials.

Design and Modulation of Negative Thermal Expansion for Epoxy Polymers.

Modulating the coefficient of thermal expansion (CTE) and realizing low or negative thermal expansion (NTE) for epoxy polymers are challenging issues. In this study, we developed an effective strategy to prepare epoxy polymers with an NTE performance. A novel motif DBCOD-NH2 based on the dibenzocyclooctadiene (DBCOD) was designed, synthesized, and utilized as a curing agent for several commercial epoxy resins. DBCOD-NH2 suppressed the thermal expansion of the epoxy polymer due to the conformational transition of DBCOD from boat to chair, resulting in low or negative CTE. The AFG90-based polymer showed the most significant thermal contraction behavior (-43.6 ppm/K, 40-80 °C) in the glassy state due to the high DBCOD content, chain rigidity, and cross-link density, which resulted from the high epoxy values, rigidity, and functionality of AFG90 resins. The structure-property interactions were examined and applied to modulate the NTE of epoxy polymers. Our findings are useful for the regulation of thermal expansion and the preparation of materials with desired CTE values.

Numerical springback prediction for high-strength aluminum alloys based on the sheet metal upsetting test

Springback prediction continues to play a special role in the process design of sheet metal forming processes. During the forming process, elastic energy is stored in the sheet metal, which is released after the tool is opened. The dimensional accuracy and the function of the component in particular can be negatively affected by this. For this reason, the springback is predicted by means of numerical modeling in order to improve the process design. The simulation accuracy depends primarily on the used material model to map the stress-dependent material behavior and the quality of the experimental input data. High-strength aluminum alloys, which have a distinctive springback behavior, have a slightly pronounced tensile-compressive asymmetry. Since tensile and compressive stresses often occur in sheet metal forming processes, the consideration of this effect can lead to an improvement in springback prediction. Besides modeling the yield locus curve for describing the yield strength in the plane stress area, the yield curve data is also relevant for determining the strain hardening behavior. The work hardening is usually characterized by the tensile test or the hydraulic bulge test, which is used to describe the material behavior in the tensile stress state. A promising experimental method for the analysis of the material in the uniaxial compressive stress state is the sheet metal upsetting test. In addition to a local characterization of sheet metal materials, this test also enables the investigation of the material behavior at significantly higher plastic strains than in the tensile test. Thus, in this contribution it is examined to what extent the sheet metal upsetting test is suitable for improving the springback prediction quality of material models in sheet metal forming processes.

Likelihood analysis of the newly observed f0(2020) , f0(2330) , and f0(2470) in J/ψ→γη′η′ as high-lying unflavored scalar mesons

Inspired by the newly observed three scalar states f0(2020), f0(2330), and f0(2470) by the BESIII collaboration in J/ψ→γη′η′, we carried out the study of spectroscopic behavior of these high-lying unflavored scalar mesonic states. In this work, using the phenomenological description of radial (n,M2) trajectory and the quark pair creation model, we discussed the assignments of the f0(2020), f0(2330), and f0(2470) associated with the f0(2200) as the isoscalar high-lying scalar mesonic states and predicted the spectroscopic properties of their high-lying partners. The present study may provide valuable information for the construction of the scalar meson family. Published by the American Physical Society 2024

Unilateral acts of states in the international legal system

The article examines unilateral acts of states in the international legal system based on a complex systemic analysis. The methodological basis was the dialectical method, which made it possible to understand the essence of international legal obligations of states in inseparable unity and general connection. The relevance of the study is determined by the trends inherent in modern international law. First, with the development of information technologies, and especially with the development of forms of information transmission, the sphere of activity of states is transformed. An increasing number of interested persons knows their positions on a wide range of international legal issues. On the one hand, it simplifies the process of identifying the state’s position when its analysis is necessary for international legal qualification. On the other hand, in such a situation, the possibilities for interpreting the behavior of a specific state from the point of view of its agreement or disagreement with a certain legal situation expand. In the practice of international relations, there is an expansion of the system of sources of international law. The study of these sources is necessary for understanding the foundations of international law, solving specific international problems and increasing the effectiveness of international cooperation. As the practice of international jurisdictional bodies accumulated, the subject of study of which was unilateral acts of states, the research emphasis shifted from establishing the essence of unilateral acts to assessing their relationship with the sources of international law. It is noted that unilateral acts play an important independent role in the modern international system, which is characterized by both fragmentation and growing globalization. Modern means of communication have made it possible to make unilateral acts one of the most frequently used tools of state interaction. The appropriateness and necessity of the development of the legal regime of unilateral acts is emphasized and substantiated. Unilateral acts of states are recognized as independent additional sources of international law capable of generating international legal norms, and they can be found in the «sources» section of many leading international legal documents.

Pentadic Cartography and India’s Foreign Policy: Insights from Jaishankar’s GLOBSEC Forum Interview

ABSTRACT India’s rise as the world’s largest democracy and its challenge to the Western-defined global order have attracted significant scholarly, political, and media attention. Using Anderson and Prelli’s pentadic cartography to enhance discursive analysis in international relations, this paper looks at journalist Maithreyi Seetharaman’s interview with Subrahmanyam Jaishankar, India’s External Affairs Minister at the GLOBSEC Forum in Bratislava, Slovakia. Depicting three interlocking maps of the symbolic landscape of the interview, we highlight the use of Seetharaman and Jaishankar’s scene-act ratio, situating India’s actions in its geopolitical contexts. Jaishankar’s dual use of materialist and idealist discourses presents India as both a reactive agent influenced by external circumstances and a proactive agent with its own distinct goals and ethical considerations. This approach offers a comprehensive understanding of international politics, balancing dominant empirical narratives in IR and emphasising a complex interplay of motives that drive state behaviour. Through this case study, we advocate for a broader application of pentadic cartography in international relations to uncover the deeper meanings and contexts that shape state actions, providing a richer, more textured understanding of geopolitics, global diplomacy and state interaction.

Constructing the Fulde-Ferrell-Larkin-Ovchinnikov State in a CrOCl/NbSe2 van der Waals Heterostructure.

Time reversal symmetry breaking in superconductors, resulting from external magnetic fields or spontaneous magnetization, often leads to unconventional superconducting properties. In this way, an intrinsic phenomenon called the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state may be realized by the Zeeman effect. Here, we construct the FFLO state in an artificial CrOCl/NbSe2 van der Waals (vdW) heterostructure by utilizing the superconducting proximity effect of NbSe2 flakes. The proximity-induced superconductivity demonstrates a considerably weak gap of about 0.12 meV, and the in-plane upper critical field reveals the behavior of the FFLO state. First-principles calculations uncover the origin of the proximitized superconductivity, which indicates the importance of Cr vacancies or line defects in CrOCl. Moreover, the FFLO state could be induced by the inherent large spin splitting in CrOCl. Our findings not only provide a practical scheme for constructing the FFLO state but also inspire the discovery of an exotic FFLO state in other two-dimensional vdW heterostructures.

Silicone Rubber-Packaged FBG Sensing Information and SSI-COV-Recognized Modal Parameters Motivated Damage Identification in Pipe Structures

Pipes are the main structures serving as the lifeline for oil and gas transportation. However, they are prone to cracks, holes and other damages due to harsh working environments, which can lead to leakage incidents and result in significant economic losses. Therefore, the development of structural health monitoring systems with advanced online diagnostic methods is of great importance for identifying local damages and assessing the safety state of pipe structures. These efforts can guide rapid repairs and ensure the continuous, efficient and cost-effective transportation of oil and gas resources. To address this problem, this paper proposes the development of a pipe monitoring system based on quasi-distributed fiber Bragg grating (FBG) sensing technology. The SSI-COV method is employed to process the sensor responses and extract the modal parameters of the structure. Based on this foundation, an enhanced damage identification index is proposed, which mitigates the effects of support and excitation positions on damage identification. The pipe structure can be regarded as a continuous super-statical beam, and based on its structural symmetry, a unit structure, specifically a stainless-steel pipe with fixed ends, is regarded as the experimental subject. Impact experiments have been conducted to analyze its behavior in both undamaged and damaged states. The research indicates that by using the proposed modal parameter identification method and the ASMDI damage index, ASMDI exhibits peak values at damage locations of the pipe structure. This allows for the identification of structural damage with high accuracy, fast processing efficiency and strong robustness. The study provides an effective and reliable damage diagnosis method, which can contribute to the refinement and visualization of pipe structural health monitoring systems.

Barriers to child vaccination: The role of international sanctions

International sanctions are often imposed with the aim of influencing the political behavior of target states, but they may have unintended consequences on public health. This study empirically examines the impact of international sanctions on child immunization rates in developing countries. Utilizing panel data from 76 developing countries between 2000 and 2019, the analysis explores how different types of sanctions, including those from the US, EU, and UN, as well as economic and unilateral sanctions, affect the immunization rates for DPT, Hepatitis B, and Measles vaccines. The findings indicate that sanctions, particularly those imposed by the US and EU, significantly reduce vaccination rates, with economic and unilateral sanctions showing the most substantial negative impact. Additionally, the study highlights the moderating role of health spending, revealing that increased healthcare investment can mitigate some of the adverse effects of sanctions. Poorer developing countries are disproportionately affected compared to their more affluent counterparts. The results underscore the need for policymakers to consider the broader public health implications of sanctions and for international efforts to ensure that essential medical resources remain accessible in sanctioned countries. This study contributes to the literature by providing comprehensive empirical evidence on the detrimental effects of international sanctions on child immunization, advocating for a balanced approach that protects public health while achieving geopolitical objectives.

A novel robust adaptive control for nonlinear uncertain quarter-vehicle suspension system in presence of unknown time delay actuation

This paper presents a novel robust adaptive control approach for nonlinear uncertain vehicle suspension system with time delayed actuation and bounded disturbances. The uncertainty and disturbance as well as the input delay on the system are all limited and unknown. This paper explores a control-oriented nonlinear model to accurately describe the dynamics of the vehicle suspension which incorporates uncertainty, disturbance and actuator delay. The controller is designed based on robust and adaptive approaches, which along with guaranteeing general goals for the suspension system is able to assure the stability of the closed-loop system in the Lyapunov concept. Also, due to the use of smooth functions in the robust controller structure, sudden changes in the behavior of system states are prevented. The simulation and comparison results in MATLAB environment show the efficiency of the proposed robust adaptive method in covering the effects of uncertainty, disturbance and time-variant actuator delay.

Molecular dynamics analysis of the crossover phenomenon in supercritical carbon dioxide

Supercritical carbon dioxide (SCO2) finds widespread applications but its complex phase behavior near and beyond the critical point remains unclear. In this work, extensive focus has been invested in the thermodynamic transitions of SCO2 from a microscopic perspective. It is revealed that both the radial distribution function and structure factor exhibit apparent crossover phenomena as temperature changes. Remarkably, our findings demonstrate an unprecedented agreement between the predicted crossover points using different functions and the experimental Frenkel Line (FL), with a deviation of merely 5.6%. By applying the same method, the FL crossover region is successfully predicted and extended up to an impressive pressure of 200 MPa. Notably, this prediction is a valuable guide in narrowing down the temperature range for further experimental tests. Concurrently, a correlation between the coordination number and the FL is discovered. Overall, our research provides compelling evidence supporting the FL as thermodynamic transitions between the gas-like and liquid-like regions and presents a novel and reliable approach for identifying the FL, which offers valuable theoretical insights into the phase behavior in the supercritical state.

Nanocasting synthesis of mesoporous CeO2 particle abrasives from mesoporous SiO2 hard templates for enhanced chemical mechanical polishing performance

Mesoporous abrasive particles exhibit superior chemical mechanical polishing/planarization (CMP) performance, as compared with the corresponding bulk materials. Nevertheless, the lack of control over the shape and particle size or distribution extremely restricts the development of mesoporous abrasives and their potential applications. To overwhelm these drawbacks, pure and ytterbium-doped mesoporous ceria (mCeO2 and mCeYbO2) spheres with well-defined morphology and good uniformity were synthesized via a straightforward nanocasting strategy using high-quality mesoporous silica spheres as hard templates and metal nitrates as precursors. The resulting samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, Zeta potential, and N2 adsorption-desorption measurements. The as-prepared mCeO2 and mCeYbO2 products exhibited enriched surface defects (trivalent Ce, vacancy oxygen, hydroxyls) and polycrystalline porous frameworks with a surface area of up to 160 m2/g and pore size of 4–7 nm. Benefiting from these synergistic attributes, the flexible and defective particle abrasives enabled significant improvements in both surface quality and removal efficiency during oxide-CMP, as compared to commercial CeO2. A possible CMP mechanism was proposed on the basis of the physical contact state, adsorption and adhesion behavior, as well as tribochemical interaction occurred at CeO2–SiO2 interfaces. This work demonstrates highly promising abrasive materials advancement combining architecture and defect engineering towards high-performance oxide-CMP.

Effect of laser remelting on the microstructures and properties of NiCoCrAlY-based coatings prepared by high-speed air fuel supersonic flame (HVAF)

In order to improve the oxidation resistance of the coating, laser remelting technology was used to remelt the HVAF multi-component modified coating. The influence of laser remelting technology on the phase state, microstructure characteristics, and isothermal oxidation behavior of coatings was studied. The experimental results indicate that a coating with complete morphology and no defects was obtained on the surface. There is a significant amount of metallurgical bonding and partial mechanical interlocking between the remelted layer and the substrate. The remelted layer is mainly composed of β-NiAl phase, accompanied by a small amount of γ′ phase and oxide phase. The microhardness test results show that the average hardness of the remelted layer is 1.1–1.42 times that of the prepared coating, and the bonding strength has increased by 23 %. After 100 h of high-temperature oxidation, the oxidation rate of the 4N3T4H remelted layer is the lowest, at 1.5 × 10−15 cm2/s, which is one order of magnitude lower than that of the as-sprayed coating. This is because after laser remelting, the remelted layer has the inherent hysteresis diffusion effect of HEA, which can improve the high-temperature oxidation resistance of the remelted layer and basically eliminate many pores and cracks contained in the HVAF coating. The coating density is significantly increased, which is conducive to hindering the diffusion of oxygen. Meanwhile, the oxide of HVAF coating mainly accumulates at pores and cracks, and there is no or late formation of uniform and dense oxide film on the surface. The surface of the remelted coating after oxidation forms a relatively uniform and dense oxide film, providing more effective protection for the substrate.