Static State Research Articles

Dynamic traffic network representation model for improving the prediction performance of passenger flow for mass rapid transit

Accurate machine learning predictions of passenger flow data for mass rapid transit (MRT) systems can considerably improve operational efficiency by enabling better allocation of train and human resources. However, such predictions are challenging because MRT networks have complex structures with route dependence and transfer stations. Although the static state of an MRT network has been computed in previous studies, a comprehensive understanding of an MRT network requires characterizing its dynamics. Therefore, this paper proposes a dynamic traffic network representation (DTNR) model that captures station features from historical traffic flows and geographical information of MRT stations. Furthermore, a multilevel attention network (MLAN) model is proposed to predict MRT passenger flow as a downstream task following the pretraining of the DTNR model. The experimental results of this study indicate that the developed DTNR and MLAN models can accurately predict MRT passenger flow. These models are widely applicable to different MRT systems and passenger flow situations, making them a valuable tool for transportation planners and operators.

Research on the Mechanical Response and Constitutive Model of 18Ni300 Manufactured by SLM with Different Build Directions.

Metals manufactured by selective laser melting (SLM) with different directions exhibit different mechanical properties. This study conducted dynamic and static mechanical tests using a universal testing machine and split-Hopkinson bar (SHPB). The mechanical properties of 18Ni300 with 0° and 90° build directions manufactured by SLM were compared, and the micro-structure properties of the two build directions were analysed by metallographic tests. The Johnson-Cook (J-C) constitutive model was fitted according to the experimental results, and the obtained constitutive parameters were verified by numerical simulations. The results revealed that the constitutive model could predict the mechanical properties of 18Ni300 in a dynamic state. The build direction had little influence on the mechanical properties in a static state, but there was a significant difference in the dynamic state. The difference in the dynamic compressive yield strength of the 18Ni300 material manufactured by SLM with two build directions was 9.8%. The SLM process can be improved to produce 18Ni300 with uniform mechanical properties by studying the reasons for this difference.

Research on the Management of College Students' Employment Process Based on the Perspective of "Diagnosis and Reform 8-Character Spiral"

Due to the lack of theoretical guidance, some college students lack systematic and scientific planning and process supervision after setting their own career goals, resulting in wavering temporary employment goals in the later stage, missing the best opportunity for employment, and unable to achieve the optimal choice for employment. This article focuses on the dual supervision of students' goal achievement process and results through the "8-character spiral of diagnosis and reform", using both dynamic and static states. It emphasizes both the "completion time" diagnosis and reform and the "progress time" diagnosis and reform. Among them, the "completion time" diagnostic reform aims to stimulate knowledge innovation, while the "progress time" diagnostic reform aims to achieve real-time regulation.

Structural visualization analysis applied to the preservation of architectural heritage: the case of stilted houses in southwest Hubei, China

Wooden buildings represent a unique aspect of China’s architectural heritage. However, over time, these buildings have suffered varying degrees of structural damage, particularly those located in China’s mountainous regions. Frequent natural disasters and inconvenient transportation further exacerbate the vulnerability of these structures. This study focuses on the typical wooden stilt houses found in the Wuling Mountain area of southwest Hubei. The different forms of columns and beams, as well as the overall structural symmetry of the stilt houses, were classified into five common structural types. Precise digital models were established via real photos and collected dimensional data, and these five models were evaluated for static, buckling, utilization, and ultimate limit states. The results indicate that: (1) overall symmetrical structures perform better than asymmetrical ones; (2) structures where all columns are grounded and act as support columns exhibit the best overall mechanical performance; and (3) transverse-tie beams(chuanfang) primarily serve a connecting role rather than a load-bearing role, thus an excess of transverse-tie beams(chuanfang) can reduce the stability of the building structure. Based on the analysis results, targeted protective measures and recommendations were proposed and verified through structural evaluations. These initiatives provide new methods and insights for the protection of architectural heritage.

A Light-Powered Self-Circling Slider on an Elliptical Track with a Liquid Crystal Elastomer Fiber.

In this paper, we propose an innovative light-powered LCE-slider system that enables continuous self-circling on an elliptical track and is comprised of a light-powered LCE string, slider, and rigid elliptical track. By formulating and solving dimensionless dynamic equations, we explain static and self-circling states, emphasizing self-circling dynamics and energy balance. Quantitative analysis reveals that the self-circling frequency of LCE-slider systems is independent of the initial tangential velocity but sensitive to light intensity, contraction coefficients, elastic coefficients, the elliptical axis ratio, and damping coefficients. Notably, elliptical motion outperforms circular motion in angular velocity and frequency, indicating greater efficiency. Reliable self-circling under constant light suggests applications in periodic motion fields, especially celestial mechanics. Additionally, the system's remarkable adaptability to a wide range of curved trajectories exemplifies its flexibility and versatility, while its energy absorption and conversion capabilities position it as a highly potential candidate for applications in robotics, construction, and transportation.

Energetic and Kinetic Competition on the Stability of Pd13 Clusters: Ab Initio Molecular Dynamics Simulations.

Material stability is the focus on both experiments and calculations, which includes the energetic stability at the static state and the thermodynamic stability at the kinetic state. To show whether energetics or kinetics dominates on material stability, this study focuses on the Pd13 clusters, because of their observable magnetic moment in experiment. Energetically, the CALYPSO searching method and first-principles calculations find that Pd13(C2) is the ground state at 0 K while the static frequency calculations demonstrate that the icosahedron Pd13(Ih) becomes more favorable on free energy as temperature increases. However, their magnetic moments (8 μB) are not in agreement with the experimental value (<5.2 μB). Kinetically, ab initio molecular dynamics simulations reveal that Pd13(C3v) (6 μB) has supreme isomerization temperature and the other 11 low-lying isomers transform to Pd13(C3v) directly or indirectly, demonstrating that Pd13(C3v) has the maximum probability to be observed in experiment. The magnetic moment difference between experiment (<5.2 μB) and this calculation (6 μB) may be due to the spin multiplicities. Our result suggests that the magnetic moment disparity between theory and experiment (in Pd13 clusters) originates from the kinetic stability.

Development of a Fast Positioning Platform with a Large Stroke Based on a Piezoelectric Actuator for Precision Machining.

In this paper, a fast positioning platform (FPP) is proposed, able to meet simultaneously the requirements of large stroke and high frequency response, developed based on a PZT (piezoelectric actuator) and a quad-parallel flexible mechanism, for application in precision machining. The FPP is driven by a high-stiffness PZT and guided by a flexible hinge-based mechanism with a quad-parallel flexible hinge. The proposed quad-parallel flexible hinge mechanism can provide excellent planar motion capability with high stiffness and good guiding performance, thus guaranteeing outstanding dynamics characteristics. The mechanical model was established, the input and output characteristics of the FPP were analyzed, and the working range (output displacement and frequency) of the FPP was determined. Based on the mechanical model and the input and output characteristics of the FPP, the design method is described for of the proposed FPP, which is capable of achieving a large stroke while responding at a high frequency. The characteristics of the FPP were investigated using finite element analysis (FEA). Experiments were conducted to examine the performance of the FPP; the natural frequency of the FPP was 1315.6 Hz, while the maximum output displacement and the motion resolution of the FPP in a static state were 53.13 μm and 5 nm, respectively. Step response testing showed that under a step magnitude of 50 μm, the stabilization times for the falling and rising edges of the moving platform were 37 ms and 26 ms, respectively. The tracking errors were about ±1.96 μm and ±0.59 μm when the amplitude and frequency of the signal were 50 μm, 50 Hz and 10 μm, 200 Hz, respectively. The FPP showed excellent performance in terms of fast response and output displacement. The cutting test results indicated that compared with the uncontrolled condition, the values of surface roughness under controlled conditions decreased by 23.9% and 12.7% when the cutting depths were 5 μm and 10 μm, respectively. The developed FPP device has excellent precision machining performance.

Feedback Control Design Strategy for Stabilization of Delayed Descriptor Fractional Neutral Systems with Order 0 &lt; ϱ &lt; 1 in the Presence of Time-Varying Parametric Uncertainty

Descriptor systems are more complex than normal systems, which are modeled by differential equations. This paper derives stability and stabilization criteria for uncertain fractional descriptor systems with neutral-type delay. Through the Lyapunov–Krasovskii functional approach, conditions subject to time-varying delay and parametric uncertainty are formulated as linear matrix inequalities. Based on the established criteria, static state- and output-feedback control laws are designed to ensure regularity and impulse-free properties, together with robust stability of the closed-loop system under permissible uncertainties. Numerical examples illustrate the effectiveness of the control methods and show that the results depend on the range of variation in the delays and on the fractional order, leading to stability analysis results that are less conservative than those reported in the literature.

Thermal postbuckling and thermally induced postbuckled flutter of tri-directional functionally graded plates in yawed supersonic flow

The current work examines the thermal postbuckling, aero-elastic flutter and thermally induced postbuckled flutter about a static equilibrium state of tri-directional functionally graded (TFGM) rectangular and tapered plates in yawed supersonic flow. Based on the von Kármán nonlinear strains, the general higher-order shear deformation theory (GHSDT) and the first-order piston theory, the governing equations of motion for TFGM plates in yawed supersonic flow are established via the Hamilton's principle. The isogemetric analysis (IGA), the load continue strategy associated with the Newton Raphson iterative technique are exploited synthetically to capture the postbuckling paths, and then the postbuckled flutter behaviors are acquired with the static equilibrium state being obtained. Comparative and convergence studies are provided to improve reliabilities of the present material model, formulae and code implementations. Subsequently, detailed parametric investigations are carried out to evaluate the influences of material volume fractions, boundary conditions and airflow angles on the thermal postbuckling, aero-elastic flutter and postbuckled flutter behaviors of TFGM plates. The results show that it is the in-plane volume fractions, rather than the thickness volume fraction, that exert a greater influence on the thermal postbuckling and flutter behaviors of TFGM plates. Furthermore, TFGM plates exhibit more diverse postbuckling paths and more complex deformations due to the inhomogeneity of the in-plane material properties compared with z-directional FGM plates.

Spatiotemporal analysis using deep learning and fuzzy inference for evaluating broiler activities

Observing poultry activity is crucial for assessing their health status; however, the inspection process is often time-consuming and labor-intensive, particularly in cases involving large numbers of chickens. Inexperienced breeders may also misjudge their activity levels, potentially missing opportunities for prevention and treatment. This study integrates traditional video surveillance with an advanced monitoring system to identify various broiler behaviors in a breeding environment. A two-stage deep learning approach is employed: in the first stage, the broilers are detected, and in the second stage, five key body points (head, abdomen, two legs, and tail) are identified. A skeleton-based model is then developed centered around the abdomen, with six angles calculated using trigonometric methods. These angles are analyzed by a long short-term memory network to estimate behaviors such as “Standing”, “Walking”, “Resting”, “Eating”, “Preening”, and “Flapping”, selecting the behavior with the highest probability. Dual-layer fuzzy logic inference systems were used to evaluate the proportion of time broilers spent in static versus dynamic states, providing a robust determination of their activity levels. Validated in a mixed-sex breeding environment, the proposed system achieved accuracies of at least 85.2% for identifying broiler type, 79.2% for identifying body parts, and 50.8% for identifying behaviors. The activity level evaluation results were consistent with those conducted by experienced poultry experts.

Multiwavelength Photoacoustic Doppler Flowmetry of Living Microalgae Cells.

Photoacoustics can provide a direct measurement of light absorption by microalgae depending on the photosynthesis pigment within them. In this study, we have performed photoacoustic flowmetry on living microalgae cells to measure their flow characteristics, which include flow speed, flow angle, flow direction, and, more importantly, the photoacoustic absorption spectrum, all by observing the photoacoustic Doppler power spectra during their flowing state. A supercontinuum pulsed laser with a high repetition frequency is used as the light source: through intensity modulation at a specified frequency, it can provide wavelength-selectable excitation of a photoacoustic signal centered around this frequency. Our approach can be useful to simultaneously measure the flow characteristics of microalgae and easily discriminate their different species with high accuracy in both static and dynamic states, thus facilitating the study of their cultivation and their role in our ecosystem.

Implementation of the non-reflection boundary for the seismic response analysis in the framework of non-local general particle dynamics

A thorough understanding of the seismic response of geotechnical structures has always been an aspiration for all engineers. Recently, the non-local general particle dynamics (NLGPD), which considers the variation of material density, has exhibited excellent promise in modelling extremely large deformation and dynamic problems. To extend the capacity of NLGPD to carry out seismic response analysis, four non-reflection boundaries are newly added in the framework of NLGPD in this paper. The viscous boundary allows wave energy to be absorbed by dashpot, in which a stress input method is proposed to input the seismic motion. The viscous-spring boundary can capture the elasticity recovery ability of the far-field medium. The free-field boundary achieves the free-field motion at lateral boundaries in the process of absorbing wave, and the corresponding relation between the points of the main model and the free-field column is determined. The static-dynamic unified boundary is introduced to model the transformation process from fixed boundary conditions in a static state to free field boundary conditions in dynamic analysis. Several representative numerical examples are solved to validate the feasibility of the proposed method. The numerical results show that the NLGPD method provides robustness and broad applicability for the seismic response analysis.

Dynamic-to-static switch of hydrogen bonds induces a metal-insulator transition in an organic-inorganic superlattice.

Hydrogen bonds profoundly influence the fundamental chemical, physical and biological properties of molecules and materials. Owing to their relatively weaker interactions compared to other chemical bonds, hydrogen bonds alone are generally insufficient to induce substantial changes in electrical properties, thus imposing severe constraints on their applications in related devices. Here we report a metal-insulator transition controlled by hydrogen bonds for an organic-inorganic (1,3-diaminopropane)0.5SnSe2 superlattice that exhibits a colossal on-off ratio of 107 in electrical resistivity. The key to inducing the transition is a change in the amino group's hydrogen-bonding structure from dynamic to static. In the dynamic state, thermally activated free rotation continuously breaks and forms transient hydrogen bonds with adjacent Se anions. In the static state, the amino group forms three fixed-angle positions, each separated by 120°. Our findings contribute to the understanding of electrical phenomena in organic-inorganic hybrid materials and may be used for the design of future molecule-based electronic materials.

Synthesizing realistic sand assemblies with denoising diffusion in latent space

AbstractThe shapes and morphological features of grains in sand assemblies have far‐reaching implications in many engineering applications, such as geotechnical engineering, computer animations, petroleum engineering, and concentrated solar power. Yet, our understanding of the influence of grain geometries on macroscopic response is often only qualitative, due to the limited availability of high‐quality 3D grain geometry data. In this paper, we introduce a denoising diffusion algorithm that uses a set of point clouds collected from the surface of individual sand grains to generate grains in the latent space. By employing a point cloud autoencoder, the three‐dimensional point cloud structures of sand grains are first encoded into a lower‐dimensional latent space. A generative denoising diffusion probabilistic model is trained to produce synthetic sand that maximizes the log‐likelihood of the generated samples belonging to the original data distribution measured by a Kullback‐Leibler divergence. Numerical experiments suggest that the proposed method is capable of generating realistic grains with morphology, shapes and sizes consistent with the training data inferred from an F50 sand database. We then use a rigid contact dynamic simulator to pour the synthetic sand in a confined volume to form granular assemblies in a static equilibrium state with targeted distribution properties. To ensure third‐party validation, 50,000 synthetic sand grains and the 1542 real synchrotron microcomputed tomography (SMT) scans of the F50 sand, as well as the granular assemblies composed of synthetic sand grains are made available in an open‐source repository.

Experimental and finite element assessment of stabilizing configurations for underground heritage sites

Heritage sites in Alexandria, Egypt, are some of the UNESCO world heritage sites at high risk from geo-environmental hazards, in particular caused by sea level rise and heavy rain due to the climate change. Recently, safeguarding UNESCO world subterranean and built heritage draws more attention. After recent environmental catastrophies in Alexandria, sustainable conservation materials and stabilizing configurations of underground monumental structures has also become urgent and highly demanded. Based on typical damage due to the heavy weathering caused by the ground water table and salt, this paper offers a guide for engineers and conservators, where rock structures consolidation and stabilizing configurations to protect these structures in the static state and against strong seismic events is presented. In this paper, typical geotechnical problems and damage to the Catacombs of of Kom El-Shoqafa are presented first, followed by an experimental evaluation methodology that includes spectroscopic and morphological characterization in addition to the mechanical testing of untreated and treated rock samples with synthetic organosilicone and acrylic compounds. The effectiveness of the new silica-based consolidants was evaluated in terms of the amount of solid adsorbed, mechanical properties (e.g., surface hardness, ultrasonic velocity, modulus of elasticity and modulus of compressive strength), and resistance to salt crystallization. The treated groups showed better mechanical strength than the control group. The ability of the treated samples to resist climate change negative impact was also greatly improved. According to laboratory tests, new silica-based hardeners and hydrophobic materials have great potential for strengthening weathered Calcarenitic rock structures. It was observed that the rock samples containing the modified binder (MTMOS + Wacher BS 15) reach higher mechanical strength parameters. After the experimental study (testing procedures), FEM analysis was performed using PLAXIS 2D code to validate the silica-based consolidants and verify their efficiency in improving the response of rock structures in static and seismic states against strong earthquake events. The results of this work confirm the high potential of low-cost injection techniques and stabilizing configurations (pre- stressed anchors and concrete friction piles) technology, confirming the possibility of achieving significant improvement in the geotechnical properties of Calcarenitic rock structures and enhancing the seismic performance of underground archaeological structures using low-cost injection technology that is easy to manufacture.

Investigation on dynamic modelling and nonlinear vibration behaviors of composite structures: A case of cable-beam model

This paper conducts a nonlinear analysis of cable-beam model of cable-stayed bridges by using the exact mode superposition method (EMSM) and the cable-beam dragging method (CBDM), respectively, comparing and exploring their theoretical foundations and practical implications. The EMSM is based on the global mode function of the cable-beam structure for nonlinear analysis, yet it requires more computational resources. The CBDM is based on the cable-beam dragging equations for nonlinear analysis, which can quickly obtain the static equilibrium state and dynamic response of the cable-beam system, but it requires some simplifying assumptions on the cable-beam connection conditions. Research results demonstrate qualitative and quantitative differences between these two methods through parametric analysis on dynamic behaviors, which provide a significant methodological study and a reference for the design and dynamics of composite structures.

Exploration on the change process of human glucocorticoid during incremental exercise load training

Glucocorticoid is a kind of hormone synthesized from glycogen, which has many physiological functions such as improving the body’s anti fatigue, anti stress, and promoting growth. Oxidation medicine is a new medical science with dual characteristics of theory and technology, which is based on biological processes. Glucocorticoids can treat many diseases, but there are certain limitations in this process, especially in diseases that play a vital role. The purpose of this paper is to explore the change process of human glucocorticoid in the process of incremental exercise load training. This paper put forward the algorithm of incremental load training and action recognition in sports training, and analyzed the changes of human glucocorticoid (GC) in the process of incremental load training based on this research. The experimental design includes the selection of research subjects, the determination of sample size, and the setting of experimental and control groups. The load was set to start at 10 a.m., with cycling training from full effort to exhaustion. The initial load was 100 W, and it increased by 20 W every 10 min. The experimental results in this paper showed that for the changes of testosterone (T) during exercise, the salivary T secretion rate immediately after exercise was significantly different from that in the resting state at the recovery period of 30 min. For the change of GC during exercise, the secretory rate of saliva GC was 2.84 mmol/min in the resting state; the secretion rate of saliva GC was 2.46 mmol/min after 20 min of exercise and 2.15 mmol/min after 40 min of exercise; the secretion rate was 1.71 mmol/min immediately after exercise and 2.55 mmol/min after 30 min rest; there was a significant difference in the secretion rate of saliva GC for 5 times. In a word, there was no significant change in saliva T/GC value during exercise and rehabilitation under static state, which was related to strong adaptability of the body and no significant stress response.

Optimizing robotic arm control using deep Q-learning and artificial neural networks through demonstration-based methodologies: A case study of dynamic and static conditions

This paper uses robot programming techniques, such as Deep Q Network, Artificial Neural Network, and Artificial Deep Q Network, to address challenges related to controlling robotic arms through demonstration learning. Static and dynamic states of the subjects were the subjects of experiments. Each method's classification accuracy process success values and experimental condition combination were evaluated. The DQN method demonstrated favourable classification accuracy outcomes, achieving an Accuracy value of 0.64 for the fixed dice and 0.52 for the moving dice. The Response value was 0.51 for the fixed dice and 0.41 for the moving dice, indicating a moderate level. The ANN method demonstrated lower accuracy, with Accuracy values of 0.59 and 0.56 and Response values of 0.61 and 0.58, respectively. The ADQN method demonstrated superior outcomes, with Accuracy values of 0.66 and 0.59 and Response values of 0.67 and 0.61. During the initial learning iterations, ADQN demonstrated the highest success rate at 33.67 %, whereas DQN and ANN achieved 28.39 % and 20.13 % success rates, respectively. As the number of iterations increased, all methods demonstrated improvement in their results. ADQN maintained a high success rate of 97.59 %, while DQN and ANN attained 82.16 % and 88.66 %, respectively. As the number of iterations increases, the results of all methods improve, but the success rate of the Artificial Deep Q Network remains high. As the number of iterations increases, both Deep Q Network and Artificial Neural Network demonstrate the potential to achieve good results. Overall, the findings support the efficacy of robot programming techniques that incorporate demonstration learning. The Artificial Deep Q Network is the most successful and fast-converging method suitable for various robot control tasks. These findings provide a foundation for future research and large-scale, comprehensive learning applications for complex rot control.

A Method to Obtain Frequency Response Functions of Operating Mechanical Systems Based on Experimental Modal Analysis and Operational Modal Analysis

The characteristics of a mechanical structure under operating conditions may differ from those in a static state. It is often more desirable to obtain the frequency response function (FRF) of the operating structure in engineering applications. While operational modal analysis (OMA) can estimate modal parameters during operation, it fails to provide mass-normalized mode shapes for FRF synthesis. This paper presents a new method using experimental modal analysis (EMA) to compensate for the absent information in OMA. It categorizes operational mode shapes into changed ones and those that remain the same compared to the static state, applying different scaling techniques accordingly. This method adapts to changes in dynamic characteristics without altering the operating conditions. Stability is emphasized throughout the process. Two examples are provided to verify the method, considering noise and incompleteness in measurement, and disturbances in dynamic properties. The proposed method is proven to be feasible and reliable to capture the changes in operational FRFs.

HIV-1-envelope trimer transitions from prefusion-closed to CD4-bound-open conformations through an occluded-intermediate state.

HIV-1 infection is initiated by the interaction between the gp120 subunit in the envelope (Env) trimer and the cellular receptor CD4 on host cells. This interaction induces substantial structural rearrangement of the Env trimer. Currently, static structural information for prefusion-closed trimers, CD4-bound prefusion-open trimers, and various antibody-bound trimers is available. However, dynamic features between these static states (e.g., transition structures) are not well understood. Here, we investigate the full transition pathway of a site specifically glycosylated Env trimer between prefusion-closed and CD4-bound-open conformations by collective molecular dynamics and single-molecule Förster resonance energy transfer (smFRET). Our investigations reveal and confirm important features of the transition pathway, including movement of variable loops to generate a glycan hole at the trimer apex and formation or rearrangements of α-helices and β-strands. Notably, by comparing the transition pathway to known Env-structures, we uncover evidence for a transition intermediate, with four antibodies, Ab1303, Ab1573, b12, and DH851.3, recognizing this intermediate. Each of these four antibodies induce population shifts of Env to occupy a newly observed smFRET state: the "occluded-intermediate" state. We propose this occluded-intermediate state to be both a prevalent state of Env and an on-path conformation between prefusion-closed and CD4-bound-open states, previously overlooked in smFRET analyses.