Initial State Research Articles

A pre-defined finite time neural solver for the time-variant matrix equation [formula omitted

During the process of the general practical applications and scientific researches, time varying issues are an inescapable challenge to be tackled. In this article, a pre-defined finite-time zeroing neural networks (PDFT-ZNN) is devoted to solve the linear time-variant matrix equation (TVME) E(t)X(t)G(t)=D(t) within a finite time (FT), which contrasts with the general ZNN (G-ZNN) models with relatively long global convergence time. Moreover, the proposed PDFT-ZNN model’s convergence time could be calculated in advance by adhering to the designed system parameters; this has nothing to do with the model’s initial state. Additionally, after the convergence analysis, if the solution error is relative small, the simple and effective method is to introduce a linear item to accelerate the convergence speed, in comparison with only the power-type ZNN models. Theory-based analysis and simulation-based results further validate that, the neural state solved by the presented FT-ZNN model can reach the theory-based solution of E(t)X(t)G(t)=D(t) within the pre-defined finite time.

Control Strategy for Building Air Conditioning Cluster Loads Participating in Demand Response Based on Cyber-Physical System

In recent years, with rising urbanization and ongoing adjustments in industrial structures, there has been a growing dependence on public buildings. The load of public buildings gradually becomes the main component of the peak load in summer, among which the load of air conditioning is particularly prominent. To clarify the key problems and solutions to these challenges, this study proposes a multi-objective optimization control strategy for building air conditioning cluster participation in demand response based on Cyber-Physical System (CPS) architecture. In a three-layer typical CPS architecture, the unit level of the CPS achieves dynamic information perception of air conditioning clusters through smart energy terminals. An air conditioning load model based on the multiple parameter types of air conditioning compressors is presented. Then, the system level of the CPS fuses multiple pieces of information through smart energy gateways, analyzing the potential for air conditioning clusters when they participate in demand response. The system of system level (SoS level) of the CPS deploys a multi-objective optimization control strategy which includes the uncertainty of the initial states of air conditioning clusters within the intelligent building energy management system. The optimal model takes into account the differences in the environmental conditions of each individual air conditioning unit within the cluster and sets different operating modes for each unit to achieve load reduction while maintaining temperatures within a comfortable range for the human body. The Multi-Objective Particle Swarm Optimization (MOPSO) algorithm based on Pareto frontiers is applied to solve this optimization control strategy and to optimize the operational parameters of the air conditioning clusters. A comparative analysis is conducted with single-objective optimization results obtained using the traditional Particle Swarm Optimization (PSO) algorithm. The case study results indicate that the proposed multi-objective optimization control strategy can effectively improve the thermal comfort of the human body towards the controlled temperatures of air conditioning clusters while meeting the accuracy of demand response. In the solution phase, the highest temperature within the air conditioning clusters is 24 °C and the lowest temperature is 23 °C. Adopting the proposed multi-objective optimization control strategy, the highest temperature is 26 °C and the lowest temperature is 23.5 °C within the clusters and the accuracy of demand response is up to 92%. Compared to the traditional PSO algorithm, the MOPSO algorithm has advantages in convergence and optimization precision for solving the proposed multi-objective optimization control strategy.

Cylindrically Symmetric Diffusion Model for Relativistic Heavy‐Ion Collisions

AbstractA relativistic diffusion model with cylindrical symmetry, which propagates an initial state based on quantum chromodynamics in time toward a thermal equilibrium limit, is derived from nonequilibrium–statistical considerations: adapting an existing framework for Markovian stochastic processes representing relativistic phase‐space trajectories, a Fokker–Planck equation is obtained for the time evolution of particle‐number distribution functions with respect to transverse and longitudinal rapidity. The resulting partially‐evolved distribution functions are transformed to transverse‐momentum and pseudorapidity space, and compared with charged‐hadron data from the CERN Large Hadron Collider.

Phenomenological studies on magnetic and mechanical remanence effects in magnetorheological fluids

Although magnetorheological fluids (MRF) have been used in science and engineering for many decades and several products based on this technology are known, there is still no consistent routine that properly takes into account major effects in the material. The aim of this work is to establish a series of steps, from the preparation of the fluid through the demagnetization routine to the choice of the angular evaluation point, which will allow to achieve stable and reproducible results regarding the material’s response to magnetic fields and mechanical actuation. As a major result of this work, a general demagnetization routine and a method for subsequent reproducible evaluation accounting for the long-term time-dependent behavior of the MRF were identified. Our efforts are aimed at exploring the following targets and questions: how can a stable initial state be ensured? Why is the initial measurement of MRF commonly hardly reproducible? How can reproducible measurements for characterizing the material be obtained? For each of these items, we developed procedures or suggest measures and discuss to what extent they solve the underlying issues and what had to be left for future investigations.

Numerical Analysis of Water–Sediment Flow Fields within the Intake Structure of Pumping Station under Different Hydraulic Conditions

The vortices, backflow, and siltation caused by sediment-laden flow are detrimental to the safe and efficient operation of pumping stations. To explore the effects of water–sediment two-phase flow on the velocity field, vorticity field, and sediment distribution within intake structures, field tests and numerical simulations were conducted in this study with consideration for the sediment concentration, flow rate, and start-up combination. We applied a non-contact laser scanner and ultrasonic Doppler velocimetry to obtain the field data and reverse modeling of the three-dimensional model of the intake structure under siltation. A multiphase flow model based on the Euler–Euler approach combined with the k-ε turbulence model was adopted for numerical simulation under 10 working conditions, and the reliability was verified with field data. The results indicate that sediment promotes the evolution of coaxial vortices into larger-scale spiral vortices along the water depth, and the process of sediment deposition is controlled by the range, intensity, and flow velocity of the backflow zone. Furthermore, the maximum volume fraction of the near-bottom sediment increased by 202.01% compared to the initial state. The increase in flow rate exacerbates the turbulence of the flow field. Although the increase in sediment concentration benefits the flow diffusion, it further promotes sediment deposition. This study provides a new idea for modeling complex surfaces and considers different operating conditions. It can serve as a scientific reference for the structural optimization and anti-siltation design of similar water-conservancy projects.

Bending strain–induced changes in perpendicular magnetic properties of Pt/Co/Pt films on flexible substrates

We studied the irreversible changes in the perpendicular magnetic properties of Pt(2.2 nm)/Co(0.8 nm)/Pt(2.2 nm) films deposited on a flexible polyethylene terephthalate substrate with bending deformation. The changes in the magnetic properties of the Pt/Co/Pt film with deformation were analyzed using magneto-optical Kerr-effect microscopy. The film was bent in one direction using cylindrical rods or semicylindrical grooves of different radii and then restored to the initial flat state. No significant changes in the magnetic properties due to bending strain were observed below a critical bending curvature. However, for bending curvatures above +0.25 mm−1 or below −0.14 mm−1, the magnetic domain shape changed from circular to elongated ellipses, perpendicular to the bending direction, and the coercivity of the film increased by 10%–30%. Furthermore, the domain wall motion exhibited a distinct anisotropic behavior, with ∼12-fold difference in the velocity of domain wall motion in different directions. Conclusively, the magnetic properties of the Pt/Co/Pt film fabricated on a flexible substrate exhibited irreversible changes beyond a critical deformation of +2.44% or −1.37%.

Lake bottom relief reconstruction and water volume estimation based on the subsidence rate of the post-mining area (Bytom, Southern Poland)

Mining activity leads to subsidence troughs and permanent changes in water relations, like the formation of anthropogenic reservoirs. In the Upper Silesian Coal Basin (S Poland), their number is so high that the area is called an anthropogenic lake district. Any form of water retention, in the face of climate change, is valuable. However, the problem is the high variability of these lakes, making it challenging to estimate water resources. An example of this type of anthropogenic lake is the Brandka Pond in Bytom. An original method was proposed, consisting of two stages: reconstruction of the lake bottom relief based on the initial state of the area relief in 1994, i.e. at the beginning of the reservoir formation, and the land subsidence rate calculated for this area. Archival cartographic materials and DEMs from LiDAR data were used and processed in the open-source geoinformation software. Orthophoto maps and satellite scenes were also collected to determine changes in the extent of the pond from 1993 to 2019. Bathymetric data obtained in 2019 during sonar measurements on the reservoir was used to verify the calculations. The pond began to form in the early 1990s, and by 2019, it had reached an area of 178,226 m2, a maximum depth of 5.8 m and a capacity of 421,173 m3. The reconstruction method is accurate and suitable for lakes over 2 m deep, and the calculated capacity differs from the bathymetric data by 0.2%.

PYROGENIC CHANGES OF BOG VEGETATION AND PEAT IN WESTERN SIBERIA

Wildfires are an important environmental factor which determines the carbon cycle intensity in mires. The article presents the assessment of the consequences of pyrogenic transformation and the current state of burntout mires in the taiga and forest-tundra zones of Western Siberia 6-8 years after the wildfire, with regard to their microhabitat heterogeneity. Field studies were conducted in 2022 on three mires (a total of 13 post-pyrogenic and pristine plots) and included a total-station survey of the surface, an assessment of the occurrence of species in the grass-dwarf shrub and moss-lichen tiers, sampling for laboratory analysis of the physical properties and botanical composition of peat. Sphagnum mosses, Polytrichum strictum, lichens and dwarf shrubs were considered as recovery indicator species. As a result of the study, it was found that the intensity of pyrogenic transformation is determined by the initial state of bog ecosystem and increases in a row: the hydro forestation site on the Bakchar raised bog - palsa - the Ust-Bakchar raised bog drained for peat extraction. At most of the studied plots, microdepressions were more susceptible to burnout, while hummocks were preserved or only partially burned out. The transformation of peat deposit properties extends beyond the layer directly exposed to burnout, and manifests itself in a decrease in water content, and an increase in ash content, bulk density and degree of humification. At the first stages of post-pyrogenic successions, similar patterns were revealed for the mires of taiga and forest-tundra zones, i.e. an intensive overgrowth with P. strictum. According to the results of the study, it was concluded that the hydroforestation site in the Bakchar bog could possibly restore the species composition of vegetation cover and resume peat accumulation. Irreversible changes in vegetation cover have occurred in the Ust-Bakchar bog, where the restoration of sphagnum mosses does not occur even 20 years after the fire.

Insight into the influence of Cu6Sn5/Cu micro-interface configuration on growth behavior of Cu-Sn interfacial intermetallic compounds in Sn/Cu solder joint

Herein, the behavior and mechanism of Cu atom diffusing across Cu6Sn5/Cu interface was researched for analyzing the influence of Cu6Sn5/Cu micro-interface configuration on growth behavior of Cu-Sn interfacial intermetallic compounds (IMCs) in Sn/Cu solder joint. The results indicate that, during Cu atoms diffusing across Cu6Sn5 (001)/Cu (110), Cu6Sn5 (110)/Cu (001), Cu6Sn5 (110)/Cu (111) interfaces, VA2→VA3 stage, VA2→VA3 stage and IA→VA1 stage are the decisive stages, respectively. At those diffusion decisive stages, the difference of average Mulliken population between Cu atom at saddle point and initial state with the surrounding atoms for Cu6Sn5 (110)/Cu (111) interface is 0.62, much greater than that for Cu6Sn5 (001)/Cu (110) and Cu6Sn5 (110)/Cu (001) interfaces with average Mulliken population difference of 0.29 and 0.20. Therefore, when Cu atom diffusing across Cu6Sn5 (110)/Cu (111) interface, the magnitude of increase in bonding strength between Cu atoms and the surrounding atoms is the largest, leading that the diffusion rate of Cu atom across Cu6Sn5 (110)/Cu (111) interface is several orders of magnitude smaller than the Cu6Sn5 (001)/Cu (110) and Cu6Sn5 (110)/Cu (001) interfaces. As a result, Cu6Sn5 (110)/Cu (111) interface shows the strongest ability for inhibiting Cu atom diffusion, and has the smallest IMC growth rate.

MHD stability of spherical tokamak equilibria with non-monotonic q-profiles

We use the 3D magnetohydrodynamic (MHD) code M3D-C1 [Jardin et al., Comput. Sci. Discovery 5, 014002 (2012)] to examine the MHD stability and subsequent evolution of NSTX shot 129169. This discharge had a period with a non-monotonic safety factor profile, q (reversed shear), which was terminated by a MHD event that abruptly lowered the central safety factor, q0, and greatly reduced the peakedness of the pressure profile. We show that the equilibrium just before the MHD event occurred was linearly unstable to many pressure-driven infernal modes. Modes with toroidal mode number n≥3 all had rational surfaces very close to the minimum value of q. However, a non-resonant pressure-driven (1, 1) mode was also present, and this dominated the nonlinear evolution. The final state in the simulation, after the MHD activity subsided, had a reduced and flattened pressure profile and a nearly monotonic q-profile, in qualitative agreement with experimental results. The initial state was also unstable to the resistive interchange criteria in the reversed-shear region, but the final state was stable everywhere. The “double tearing mode” (DTM) does not appear to play a role in the MHD activity of this discharge. In Appendix A, we show that in a torus, the DTM is strongly stabilized by pressure, but it is destabilized in cylindrical geometry (which has been the most extensively analyzed in the literature).

Analyzing the Current State and Visibility of Diversity, Equity, and Inclusion Initiatives at Urology Residency Programs

ObjectiveTo analyze AUA urology residency program websites to determine visibility of DEI initiatives. There is growing interest in diversity, equity, and inclusion (DEI) initiatives by urology applicants, and in recent years, urology programs have invested in efforts to promote DEI. MethodsAll ACGME-accredited urology residency program with a website were assessed. Military programs were excluded. A DEI Score Card was developed using published pillars of DEI, including five domains: departmental inclusion, pipeline growth, departmental education, community engagement, and faculty demographics. Program Doximity rank, address, and surrounding demographics were collected to determine predictors of investing in DEI. Results141 urology residency websites were included for analysis. Only 40.7% of programs referenced DEI on their webpage, and 21.4% offered funded mentorship opportunities. Department education and community engagement were the least popular initiatives. The Western, Northeastern, and North Central sections had the highest DEI total score with wide variation across domains. Mention of DEI was not associated with program’s county-level social vulnerability or percent minority but was associated with being a top 50 program (OR=4.0; 95% CI 1.8, 8.9; p=0.0007). DiscussionLess than half of academic urology programs' websites referenced DEI initiatives. Using a DEI score card, our study shows that investment in diversity, equity, and inclusion varies widely by AUA section, and greater investment is positively correlated with program rank. Our DEI score card serves as a tool that programs can use to assess their current DEI investment, identify areas for improvement, and ensure existing initiatives are visible to applicants.

Predicting Ion Sequestration in Charged Polymers with the Steepest-Entropy-Ascent Quantum Thermodynamic Framework.

The steepest-entropy-ascent quantum thermodynamic framework is used to investigate the effectiveness of multi-chain polyethyleneimine-methylenephosphonic acid in sequestering rare-earth ions (Eu3+) from aqueous solutions. The framework applies a thermodynamic equation of motion to a discrete energy eigenstructure to model the binding kinetics of europium ions to reactive sites of the polymer chains. The energy eigenstructure is generated using a non-Markovian Monte Carlo model that estimates energy level degeneracies. The equation of motion is used to determine the occupation probability of each energy level, describing the unique path through thermodynamic state space by which the polymer system sequesters rare-earth ions from solution. A second Monte Carlo simulation is conducted to relate the kinetic path in state space to physical descriptors associated with the polymer, including the radius of gyration, tortuosity, and Eu-neighbor distribution functions. These descriptors are used to visualize the evolution of the polymer during the sequestration process. The fraction of sequestered Eu3+ ions depends upon the total energy of the system, with lower energy resulting in greater sequestration. The kinetics of the overall sequestration are dependent on the steepest-entropy-ascent principle used by the equation of motion to generate a unique kinetic path from an initial non-equilibrium state.

Effect of Different Laser Parameters on Surface Physical Characteristics and Corrosion Resistance of 20 Steel in Laser Cleaning

The rusting of metals brings huge losses to the industry every year, and post-treatment of rusted metals to restore their properties to the initial state is a hot topic of current research. In particular, 20 steel, which is widely used in various structural components such as ships, is prone to oxidation in atmospheric environment. Therefore, in this study, a nanosecond pulsed laser was used to remove the rust layer on the surface of 20 steel. The effects of different energy densities and spot overlap rates on the roughness, surface morphology, chemical composition, microhardness and corrosion resistance of the rust layer were analyzed. The results showed that the best cleaning effect was achieved at an energy density of 4.26 J/cm2 and a spot overlap rate of 75%. Under these conditions, the rust layer was completely removed without damage to the substrate, and it even improved the corrosion resistance of 20 steel. At energy densities of 1.42 J/cm2 and 2.84 J/cm2, the rust layer was not completely removed, while at 5.68 J/cm2, the rust layer was removed but the substrate was damaged. In addition, the mechanism of rust removal and substrate damage is discussed.

Enhance the coherence of open two-level system through the superposition of environments

Dynamics of a two-level system in the superposition of two dephasing environments with Ohmic-like spectral density is studied when considering initial system-environment correlations. The quantum system and one environment are treated as whole thermal equilibrium state, while the other environment is at thermal equilibrium state alone. Which environment the system interacts with is determined by an ancillary two-level system. When the system interacts with mixture of two sub-Ohmic environments, initial correlations can make the mixed dynamics non-Markovian. For two identical sub-Ohmic environments, if performing the projective measurement on the ancillary two-level system at the special time points, whatever the initial state of the system is, the coherence can be enhanced. For two different environments with βħω0/2>>, we get the approximate expression about the coherence of the system when measuring the ancillary two-level system.

Neural Network-Based Fixed-Time Tracking Control for Input-Quantized Nonlinear Systems With Actuator Faults.

This study reports a fixed-time tracking control problem for strict-feedback nonlinear systems with quantized inputs and actuator faults where the total number of faults is allowed to be infinite. By taking advantage of radial basis function neural networks (RBFNNs), unknown nonlinear function terms in the system dynamic model can be effectively approached. In addition, based on the sector property of quantization nonlinearities and the structure of the actuator fault model, novel adaptive estimations and innovative auxiliary design signals are constructed to compensate for the influence caused by actuator faults and quantized inputs properly in the fixed-time convergence settings. Then, rigorous theoretical analysis manifests that the proposed control scheme can make the output tracking error converge to a small neighborhood of the origin within a fixed time, and the upper bound of the setting time not only does not depend on initial states of the system but also can be preassigned by selecting parameters appropriately. Meanwhile, all the signals in the closed-loop system remain bounded. Finally, a numerical example and a practical example of a single-link manipulator are presented to demonstrate the effectiveness of the proposed control algorithm.

Resonant multiphoton processes and excitation limits to structural dynamics.

Understanding the chemical reactions that give rise to functional biological systems is at the core of structural biology. As techniques are developed to study the chemical reactions that drive biological processes, it must be ensured that the reaction occurring is indeed a biologically relevant pathway. There is mounting evidence indicating that there has been a propagation of systematic error in the study of photoactive biological processes; the optical methods used to probe the structural dynamics of light activated protein functions have failed to ensure that the photoexcitation prepares a well-defined initial state relevant to the biological process of interest. Photoexcitation in nature occurs in the linear (one-photon per chromophore) regime; however, the extreme excitation conditions used experimentally give rise to biologically irrelevant multiphoton absorption. To evaluate and ensure the biological relevance of past and future experiments, a theoretical framework has been developed to determine the excitation conditions, which lead to resonant multiphoton absorption (RMPA) and thus define the excitation limit in general for the study of structural dynamics within the 1-photon excitation regime. Here, we apply the theoretical model to bacteriorhodopsin (bR) and show that RMPA occurs when excitation conditions exceed the linear saturation threshold, well below typical excitation conditions used in this class of experiments. This work provides the guidelines to ensure excitation in the linear 1-photon regime is relevant to biological and chemical processes.

Integrated entry guidance with no-fly zone constraint using reinforcement learning and predictor-corrector technique

This paper presents an integrated entry guidance law for hypersonic glide vehicles with no-fly zone constraint. Existing methods that employ predictor-corrector technique and lateral guidance logic for both guidance and avoidance, may have limitations in response time and maneuverability when facing sudden threats, because the guidance cycle is limited by computational efficiency and the bank angle magnitude cannot be adjusted according to the urgency of the avoidance. To overcome these challenges, the proposed method divides the entry process into safe flight stages and no-fly zone avoidance stages, and introduces reinforcement learning to develop an intelligent avoidance strategy for the latter. This division reduces the complexity of the learning problem by restricting the state space and increases the applicability in the presence of multiple no-fly zones. The trained avoidance strategy can directly output continuous bank angle command through a single forward calculation, considering both guidance and avoidance requirements. This enables the full utilization of the vehicle’s maneuverability and supports a high command update frequency to effectively handle threats. Additionally, a network trained via supervised learning is employed to generate reference commands, accelerating the training convergence of reinforcement learning. Simulation results demonstrate the effectiveness of the proposed guidance law, highlighting its high computational efficiency, command stability, and robustness. Importantly, the approach offers convenience in extending to multiple no-fly zones and accommodating vast initial state spaces.

Quantum algorithms for matrix operations and linear systems of equations

Fundamental matrix operations and solving linear systems of equations are ubiquitous in scientific investigations. Using the ‘sender-receiver’ model, we propose quantum algorithms for matrix operations such as matrix-vector product, matrix-matrix product, the sum of two matrices, and the calculation of determinant and inverse matrix. We encode the matrix entries into the probability amplitudes of the pure initial states of senders. After applying proper unitary transformation to the complete quantum system, the desired result can be found in certain blocks of the receiver’s density matrix. These quantum protocols can be used as subroutines in other quantum schemes. Furthermore, we present an alternative quantum algorithm for solving linear systems of equations.

Exploring the Relationship between Environmental Cognition, Pro-Environmental Behavior, and Mental Health among Adolescents: A Narrative Review

Introduction: Adolescents’ cognition, behavior, and attitudes are essential for environmental conservation; hence, the physical environment is inevitable in their mental health. The environment can influence adolescents’ sense of support, freedom, and the stimulation they seek in life. Environmental factors such as pollution, weather, lifestyle changes, and working conditions significantly influence adolescents' mental health. Knowing and learning about environmental cognition and its influence on adolescents is vital. Objective: To understand the relationship between environmental cognition, pro-environmental behavior, and mental health among adolescents with the help of a narrative approach. Methods: The present article ‘employed a narrative review.’ Research articles were taken from four databases, PubMed, Research Gate, Web of Science, and Science Direct, using the PRISMA procedure from 2000 to 2023. The data was collected from various databases and narrowed down for the results. Results: This study proves a strong relationship between environmental cognition, pro-environmental behavior, and adolescents' mental health. Twenty-six selected research studies out of 45 initial studies state that solid environmental cognition may lead to enhanced pro-environmental behavior, which is crucial to adolescents’ mental health and well-being. Furthermore, pro-environmental cognition wholly mediated the relationship between environmental behavior and mental well-being. Conclusion: Implications of this study concentrate on developing focused interventions, creating urban planning policies, and developing adolescent-friendly community designs, which are solid pillars for promoting mental health. Adolescents must be motivated to protect the environment to become pioneers of pro-environmental behavior.

Cosmological collider signal from non-Bunch-Davies initial states

Cosmological collider signal from non-Bunch-Davies initial states