Structure Model Research Articles

Research on Lightweight Rail Vehicle Body Based on Sensitivity Analysis

In view of the development trend of rail vehicles towards higher operating speed and low power consumption, a scheme for a lightweight rail vehicle body is proposed, based on sensitivity analysis. Using topology optimization of the vehicle body section structure, finite element models of the vehicle body section structure under single working conditions and multiple working conditions were established, respectively, and the force transmission path of the vehicle body structure under different working conditions was obtained under different working conditions. The topology of the cross-sectional structure of the vehicle body was optimized by the compromise planning method with weights. Then, a reconstruction and performance analysis of the car body section was carried out based on the optimization results and finally the finite difference method was used to analyze the sensitivity of the vehicle body structure and the vehicle body size was optimized based on the sensitivity analysis results. The results showed that the weight reduction rate of the railway vehicle body section stiffened plate was 4.47% compared to the optimization period and the modal performance analysis results of the optimized structure met the requirements. The weight reduction ratio of the optimized body structure was 21.6%

Spatial Chromosome Organization and Adaptation of Escherichia coli under Heat Stress.

The spatial organization of bacterial chromosomes is crucial for cellular functions. It remains unclear how bacterial chromosomes adapt to high-temperature stress. This study delves into the 3D genome architecture and transcriptomic responses of Escherichia coli under heat-stress conditions to unravel the intricate interplay between the chromosome structure and environmental cues. By examining the role of macrodomains, chromosome interaction domains (CIDs), and nucleoid-associated proteins (NAPs), this work unveils the dynamic changes in chromosome conformation and gene expression patterns induced by high-temperature stress. It was observed that, under heat stress, the short-range interaction frequency of the chromosomes decreased, while the long-range interaction frequency of the Ter macrodomain increased. Furthermore, two metrics, namely, Global Compactness (GC) and Local Compactness (LC), were devised to measure and compare the compactness of the chromosomes based on their 3D structure models. The findings in this work shed light on the molecular mechanisms underlying thermal adaptation and chromosomal organization in bacterial cells, offering valuable insights into the complex inter-relationships between environmental stimuli and genomic responses.

Gradient anisotropic design of Voronoi porous structures

Gradient and anisotropic design have proved to be two effective approaches for customizing lightweight porous parts in recent years due to their outstanding performances comparing to the uniform porous ones, such as high specific strength, specific surface areas and high energy and shock absorption capacities, etc. However, it is still challenging to integrate both gradient and anisotropy into a same porous part, while making it profile adaptable simultaneously. In this paper, a novel gradient anisotropic design method of Voronoi porous structures for parts customization is proposed driven by the stress field of a part in a specific application scenario. Firstly, the stress field is decomposed into a stress scalar field and a stress direction field. The former is mapped into the Voronoi site distribution by a weighted random sampling algorithm that globally controls the gradient of the mechanical properties, while the latter is applied to adjust the shapes and orientations of the Voronoi cells for tailoring the anisotropy locally. Then, a lightweight gradient anisotropic Voronoi porous (GAVP) part is customized based on a Voronoi cell growth strategy with preferred directions, making the porous part highly profile adaptable. Finally, the influences of the design parameters on the mechanical properties of the GAVP parts are analyzed in detail, and the proposed design method is further validated experimentally and numerically. The results show that the integration of gradient and anisotropy significantly enhances the mechanical properties of a GAVP part compared to the corresponding gradient porous or anisotropic porous ones, because our GAVP structure modeling method realize a more optimal allocation of material locally, which makes the stress distribution much more even.

Research on the application of DIC technology in model tests of hydraulic structures

Digital image correlation (DIC) is a noncontact measurement technique that can visualize and measure a model body in an entire field without interference. This study performed the structural model test of a cemented sand and gravel (CSG) dam. The scale-free DIC technology was applied to the model test to monitor the CSG model dam during overload damage. The study results demonstrated the following results:1) The CSG dam experienced sliding shear failure along the dam foundation with an overload coefficient of 5.2 during failure. 2) The use of DIC technology for measurement could reflect the generation and development of the damage process of the model dam. 3) The DIC technique used in this test achieved an observation accuracy of 2 mm for displacement and 530 με for strain. 4) The conclusions of the measurement results of the DIC technique and the traditional method are identical. The DIC technique has considerable application potential in the model tests of hydro-structures. This study provides a new measurement method for hydraulic structure model tests and supports the development of an intelligent monitoring platform for subsequent hydraulic structure model tests.

Construction and Application of Psychological Entropy Dissipation Model in Teenagers Resilience

This paper utilizes the psychological entropy dissipative structure theory to study adolescent psychological development from a new perspective, to dissect the dissipative structure of the psychological quality education system, and to study the prevention and treatment mechanism of psychological crisis. Based on the research data of secondary school students in China's second-tier urban areas, this study adopts the psychological entropy and dissipative structure model to compare the differences in the effects of the two quality education modes with and without team practice activities on the cultivation of adolescents' psychological resilience qualities by using the team social practice program as an example, and to form the entropy-reducing program for exploring the improvement of adolescents' psychological resilience in the quality education and cultivation reform program. The results show that the overall level of psychological resilience of the subjects is relatively satisfactory, the traditional education model of students in the training with the knowledge of the problem of the brush, a moderate amount of brush the amount of the problem of the problem can enable students to train a relatively good positive state of mind, the team practice activities of the students through the interpersonal connection, through the interaction of members of the team to obtain mutual support, more flexible response to emergencies and introspection and enhancement. It is suggested that in the process of comprehensive quality education for adolescents, the psychological stress management of adolescents can be realized by increasing the number of students from different schools to form irregular teams to carry out multiple team social practices. This study provides new theoretical perspectives and analytical methods for secondary school students' psychological quality education, and is of positive significance for the promotion of youth's healthy growth and the effective prevention of psychological crisis.

Psychometric properties of the Chinese version of the Highly Sensitive Child Scale among Chinese adolescents

The present study aimed to develop the Chinese version of the Highly Sensitive Child (C-HSC) Scale and examine its psychometric properties in Chinese participants (grade 4 ∼ fourth year of college), and preliminarily explores what kinds of Environmental Sensitivity groups exist among Chinese adolescents. A total of 9091 data (46.65 % males, 9–23 years old) points were collected to examine the psychometric properties of the C-HSC scale, and half of the data were used to explore the types of Environmental Sensitivity groups. The results showed that the scale has good psychometric properties. First, the scale composed of three dimensions is consistent with the Highly Sensitive Child Scale, which is more consistent with the bifactor structure model than the three-factor structure model. In addition, the scale has good reliability, convergent validity and discriminant validity; and has full configural, full metric, and full scalar invariance (partial scalar invariance across developmental stages) across genders and developmental stages. Finally, three groups of Environmental Sensitivity were found among Chinese adolescents, namely, high (orchids), medium (tulips), and low (dandelions) Environmental Sensitivity. The proportions of low, medium and high environmental sensitivity were 24.09 %, 40.64 % and 35.27 %, respectively.

Optimization of an architected composite with tailored graded properties

The aim of the present study is to design a solid material with specific and tailored mechanical properties through a suitably defined design framework and to evaluate the effectiveness of different microstructure geometries in an engineering perspective. To these ends, topology optimization algorithms are applied on a 2D homogenized equivalent model of a periodic structure. The design framework, developed in a previous work for 2D lattices made of regular hexagons, is here expanded and validated also in the cases of circular and square unit cells. The proposed approach involves optimizing porosity distribution of a homogenized equivalent solid, obtained through a Bloch–Floquet-based analysis, within a 2D lattice of regular unit cells forming the core element of a sandwich panel. Finite-element analyses on homogenized and fine structural models are carried out in order to validate the procedure, beyond the particular choice of the unit cell geometry and to detect its effectiveness and limits.

Analysis of the Boss Structure of Type Ⅳ Composite Vessel for a High-Pressure Hydrogen Tube Trailer

Currently, large-volume type IV composite vessel tube trailers garner significant attention and development within the hydrogen energy storage and transportation industry due to their cost-effectiveness and practicality. This study aims to assess the static strength and sealing performance of the boss structure in order to optimize its design. Firstly, a model of the mouth structure of type IV vessels was constructed to analyze the stress distributions in the boss and liner. Subsequently, innovative boss and liner structures were developed based on the primary mouth structure to investigate the impact of geometric dimensions through finite element analysis. This study revealed that changes in geometrical dimensions led to significant alterations in the stresses of the plastic liner in comparison to metallic bosses. Building upon these findings, the structural safety and sealing performance of the boss and liner structure were further validated through finite element analysis. The outcomes of this research can serve as a reference for guiding the structural design of bosses and aiding in the development of hydrogen storage vessels.

Performance Evaluation of Physical Properties on Zinc Sulfide (ZnS)-based Field Effect Transistor

The paper presents the performance evaluation of physical properties on Zinc Sulfide (ZnS)-based Field Effect Transistor. The most famous III-V compound-based semiconductor devices have several affected to the environment and the toxic contents are directly responded to the society. Due to the lack of technology on nontoxic compound-based semiconductor device fabrications, the novel device with II-VI compound materials are challenging issues for the environments. The specific objectives of doing research on fabrication of II-VI compound-based semiconductor devices in advanced laboratories are to emphasize the numerical modeling of the device structure and designing the FET based on ZnS material, to contribute the mathematical model for physical characteristics of the FET structure and the modification of the device structure will be easily established by using numerical simulation. The mathematical analyses on physical properties of device structure with ZnS material are confirmed and observed the several properties of electrical and electronic characteristics. The detailed implementations for ZnS-based FET devices are performed and evaluated the performance of the developed FET devices. There are two steps analyses in physical properties of ZnS-based FET devices with numerical implementation by MATLAB languages. The results observed in this study could be confirmed with the recent works from several research laboratories and the developed ZnS-based FET devices could be utilized in high performance wide band applications on switching in the power electronics and amplification purposes in modern amplifier design in real world applications.

Optimization of geopolymer pervious concrete design using multi-phase discrete element modeling

This study aims to optimize mix designs of geopolymer pervious concrete using multi-phase discrete element modeling. Metakaolin based geopolymer concrete was prepared with different mix designs for laboratory testing. A multi-phase discrete element model (DEM) for pervious concrete was developed with randomly generated porous structure and realistic contact models between each component. Contact model parameters were calibrated using orthogonal analysis based on measurements of mechanical strengths and elastic modulus. Results of model validation indicate that the developed numerical model has good reliability to predict mechanical properties of pervious concrete with the influence of porosity. Both actual and simulated pervious concrete specimens present consistent crack propagation patterns and failure behavior. The optimization of mixture design is conducted by considering aggregate gradation and aggregate to paste ratio of geopolymer pervious concrete, which are based on experimental results and post-calibration simulations. The gradation with larger size aggregate is suitable for preparing geopolymer pervious concrete with higher permeability and tensile strength. More importantly, it is feasible to reduce paste content in geopolymer pervious concrete while maintaining similar or even higher mechanical strengths, which reduces the embedded carbon footprint. The study findings demonstrate the beneficial use of numerical modeling to determine the optimized mix design of composite material such as geopolymer pervious concrete.

Ascorbate peroxidase catalyses synthesis of protocatechualdehyde from p-hydroxybenzaldehyde in Lycoris aurea

Protocatechualdehyde is a plant natural phenolic aldehyde and an active ingredient with important bioactivities in traditional Chinese medicine. Protocatechualdehyde is also a key intermediate in the synthesis of Amaryllidaceae alkaloids for supplying the C6-C1 skeleton. However, the biosynthesis of protocatechualdehyde in plants remains obscure. In this study, we measured the protocatechualdehyde contents in the root, bulb, scape and flower of the Amaryllidaceae plant Lycoris aurea (L’Hér.) Herb., and performed the correlation analysis between the protocatechualdehyde contents and the transcriptional levels of the phenolic oxidization candidate protein encoding genes. We found that a novel ascorbate peroxidase encoded by the contig_24999 in the L. aurea transcriptome database had potential role in the biosynthesis of protocatechualdehyde. The LauAPX_24999 gene was then cloned from the cDNA of the scape of L. aurea. The transient expression of LauAPX_24999 protein in Arabidopsis protoplasts demonstrated that LauAPX_24999 protein was localized in the cytoplasm, thus belonging to Class II L-ascorbate peroxidase. Subsequently, LauAPX_24999 protein was heterogenously expressed in Escherichia coli, and identified that LauAPX_24999 biosynthesized protocatechualdehyde from p-hydroxybenzaldehyde using L-ascorbic acid as the electron donor. The protein structure modelling and molecular docking indicated that p-hydroxybenzaldehyde could access to the active pocket of LauAPX_24999 protein, and reside at the δ-edge of the heme group while L-ascorbic acid binds at the γ-heme edge. To our knowledge, LauAPX_24999 is the first enzyme discovered in plants able to biosynthesize protocatechualdehyde from p-hydroxybenzaldehyde, and offers a competent enzyme resource for the biosynthesis of Amaryllidaceae alkaloids via synthetic biology.

A diamond-bearing core-mantle boundary on Mercury

Abundant carbon was identified on Mercury by MESSENGER, which is interpreted as the remnant of a primordial graphite flotation crust, suggesting that the magma ocean and core were saturated in carbon. We re-evaluate carbon speciation in Mercury’s interior in light of the high pressure-temperature experiments, thermodynamic models and the most recent geophysical models of the internal structure of the planet. Although a sulfur-free melt would have been in the stability field of graphite, sulfur dissolution in the melt under the unique reduced conditions depressed the sulfur-rich liquidus to temperatures spanning the graphite-diamond transition. Here we show it is possible, though statistically unlikely, that diamond was stable in the magma ocean. However, the formation of a solid inner core caused diamond to crystallize from the cooling molten core and formation of a diamond layer becoming thicker with time.

Digital models of the deep structure of the Earth’s crust in the Eurasian Basin of the Arctic Ocean

Digital models of the deep structure of the Earth’s crust in the Eurasian Basin of the Arctic Ocean

Demand Response Power-Gas Interconnection Energy System and Power Metering Based on SOGA

Under the double background of global energy crisis and environmental pollution, China vigorously develops renewable energy while accelerating the construction of energy Internet. Taking demand response into account, this paper proposes the optimal design of power-gas interconnection energy system and power metering, and establishes the optimization research model of IEGES (integrated electricity-gas energy system) with demand response. Firstly, the structure model of the electric-gas interconnection energy system with CHP (Cogeneration, combined heat and power) as the core is constructed, and the energy conversion relationship and different energy flow directions of the coupling equipment are expounded from three aspects. The natural gas source point, pipeline equation, power side branch equation, voltage and current equation are modeled and sorted out, and the square term in the equation is linearized by second-order cone programming method, and the mixed integer nonlinear programming problem is transformed into mixed integer linear programming problem. A single objective genetic algorithm with “elite strategy” was selected to solve the equipment capacity optimization problem of IEGES system with system economy as the optimization objective. After a long time of parameter combination attempts, the current population size is 30, the number of iterations is 600, the crossover rate is 0.8, and the heritability is 0.3. The above parameters can obtain better convergence results on the basis of considering the operation time. Finally, a stochastic optimization method of energy Internet considering integrated demand response and uncertainty of wind power is proposed, which aims to meet the energy demand of end users while minimizing the operating cost of the system. The comprehensive demand response strategy including internal and external demand response is considered in the model. Internal demand response is realized by adjusting the internal operation mode of EH, while external demand response is implemented by the end user’s active response, and the load is time-shifted or interrupted under the guidance of external signals.

Anxiety, a significant risk factor for coronary artery disease: what is the best index

BackgroundCoronary artery disease (CAD) is known as the leading cause of disability and death globally. Anxiety disorders are also recognized as common types of mental disorders that substantially impact global health. Iran ranks among the countries with a high incidence of CAD and anxiety disorders. Therefore, the present study aims to determine the potential association and epidemiological aspects of anxiety and CAD within the population of Mashhad, the second most popoulos city in Iran.MethodsThe present study is based on extracted data from the Mashhad stroke and heart atherosclerotic disorder (MASHAD) study which is a 10-year prospective cohort study intended to assess the effects of various CAD risk factors among Mashhad city residents. Anxiety scores were assessed at the baseline using Beck Anxiety Inventory and individuals were classified based on the BAI 4-factor structure model which included autonomic, cognitive, panic, and neuromotor components. Accordingly, the association between baseline anxiety scores and the BAI four-factor model with the risk of CAD events was analyzed using SPSS software version 21.ResultsBased on the results, 60.4% of the sample were female, and 5.6% were classified as having severe forms of anxiety. Moreover, severe anxiety was more prevalent in females. Results showed a 1.7% risk of CAD (p-value < 0.001) over 10 years with one unit increase in anxiety score. Based on the 4-factor model structure, we found that only panic disorder could significantly increase the risk of CAD by 1.1% over the 10-year follow-up (p-value < 0.001).ConclusionAnxiety symptoms, particularly panic disorder, are independently and significantly associated with an increased overall risk of developing CAD over a 10-year period. Therefore, further studies are warranted to investigate the mechanisms through which anxiety may cause CAD, as well as possible interventions to mitigate these processes.

ERoots: A three-dimensional dynamic growth model of rice roots coupled with soil

Root architecture systems (RAS) reflect the spatial structure of roots in soil. To clarify the structure and distribution of rice roots and investigate the coupling between roots and soil, wetland rice was selected as the experimental object, and a three-dimensional (3D) growth model of rice root environment-roots (ERoots) based on the parameter Lindenmayer system (L-system) was proposed. ERoots combines a root morphological structure model with a growth model and defines L-system grammar iteration rules with the unit time and unit step length as parameters. At the same time, the basic growth parameters of rice roots were obtained via destructive detection, and 3D growth visualisation of roots was realised via MATLAB. In the soil coupling process, a soil nutrient simulation map was constructed based on the spatial soil characteristics per unit volume, and an adjustment strategy for roots reaching the growth boundary was designed. The flexibility of the model coupled with soil was reflected in the tropisms of root growth, growth rate and root branching strategy. Finally, combined with soil spatial characteristic simulation, geometric growth boundary and 3D root growth model, the ability of 3D growth visualisation of rice roots was verified under three soil conditions: (1) unconfined root growth, (2) confined spatial root growth, and (3) root growth with tropisms. The results indicated that the ERoots root model basically realised coupling with soil and achieved a satisfactory simulation effect in regard to the rice morphological structure. This study provides a reference for 3D growth modelling and visualisation of other crop roots.

Multi-load effect on the deformation analysis of composite nano reinforced origami sandwich panel

Graphene origami in a copper matrix is used as a composition of core in a sandwich panel between two piezoelectric/piezomagnetic layers. More accurate modeling of the composite sandwich structure is performed using a higher-order model including thickness stretching term. Principle of virtual work is used in order to derive governing equations in terms of resultant components of force and moment as well as electromagnetic loads. The resultant components are derived in higher-order framework with accounting electric and magnetic potentials using the effective material properties of graphene origami in Halpin-Tsai and rule of mixture framework. The deformation/strain/stress components are analytically obtained in terms of thermal, mechanical, electrical, and magnetic loads as well as folding degree and content of graphene origami. Verification is performed for justification of the numerical results. A foldability dependent parametric analysis is presented to show controllability of stress, strain and deformations along the thickness direction.

RCSB protein data bank: Exploring protein 3D similarities via comprehensive structural alignments.

Tools for pairwise alignments between three-dimensional (3D) structures of proteins are of fundamental importance for structural biology and bioinformatics, enabling visual exploration of evolutionary and functional relationships. However, the absence of a user-friendly, browser-based tool for creating alignments and visualizing them at both 1D sequence and 3D structural levels makes this process unnecessarily cumbersome. We introduce a novel pairwise structure alignment tool (rcsb.org/alignment) that seamlessly integrates into the RCSB Protein Data Bank (RCSB PDB) research-focused RCSB.org web portal. Our tool and its underlying application programming interface (API, alignment.rcsb.org) empowers users to align several protein chains with a reference structure by providing access to established alignment algorithms (FATCAT, CE, TM-align, or Smith-Waterman 3D). The user-friendly interface simplifies parameter setup and input selection. Within seconds, our tool enables visualization of results in both sequence (1D) and structural (3D) perspectives through the RCSB PDB RCSB.org Sequence Annotations viewer and Mol* 3D viewer, respectively. Users can effortlessly compare structures deposited in the PDB archive alongside more than a million incorporated Computed Structure Models (CSMs) coming from the ModelArchive and AlphaFold DB. Moreover, this tool can be used to align custom structure data by providing a link/URL or uploading atomic coordinate files directly. Importantly, alignment results can be bookmarked and shared with collaborators. By bridging the gap between 1D sequences and 3D structures of proteins, our tool facilitates deeper understanding of complex evolutionary relationships among proteins through comprehensive sequence and structural analyses. The alignment tool is part of the RCSB PDB research-focused RCSB.org web portal and available at rcsb.org/alignment. Programmatic access is available via alignment.rcsb.org. Frontend code has been published at github.com/rcsb/rcsb-pecos-app. Visualization is powered by the open-source Mol* viewer (github.com/molstar/molstar and github.com/molstar/rcsb-molstar) plus the Sequence Annotations in 3D Viewer (github.com/rcsb/rcsb-saguaro-3d).

What is the Effect of Restrictions Imposed by Principal Components Analysis on the Empirical Performance of Dynamic Term Structure Models?

What is the Effect of Restrictions Imposed by Principal Components Analysis on the Empirical Performance of Dynamic Term Structure Models?

The complete exterior spacetime of spherical Brans-Dicke stars

We derive the complete expression for the Brans Class I exterior spacetime explicitly in terms of the energy and pressures profiles of a stationary spherisymmetric gravity source. This novel and generic expression is achieved in a parsimonious manner, requiring only a subset of the Brans-Dicke field equation and the scalar equation. For distant orbiting test particles, this expression promptly provides a simple, closed and exact formula of the γ Eddington parameter, which reads γexact=ω+1+(ω+2)Θω+2+(ω+1)Θ, where Θ is the ratio of the star's “total pressure” integral over its energy integral. This non-perturbative result reproduces the usual Post-Newtonian ω+1ω+2 expression in the case of a “Newtonian star”, in which the pressure is negligible with respect to the energy density. Furthermore, it converges to the General Relativity value (γGR=1) as the star's equation of state approaches that of ultra-relativistic matter (in which case Θ approaches 1), a behavior consistent with broader studies on scalar-tensor gravity. Our derivation underscores the essence of these results involving (1) the key relevant portion of the Brans-Dicke field equations, (2) the uniqueness of the Brans Class I vacuum solution for the non-phantom action, viz. ω>−3/2, and (3) the involvement of only two free parameters in this solution, hence requiring two quantities (energy and pressure integrals) of the mass source to fully characterize the solution. From a practical standpoint, it elucidates how a given stellar interior structure model determines the star's exterior gravitational field and impacts the motions of light objects (such as planets and accretion disks) orbiting it.