Equivalent Core Research Articles

Heat strain differences walking in hot-dry and warm-wet environments of equivalent wet bulb globe temperature

ABSTRACT Wet bulb globe temperature (WBGT) is a commonly used measure to predict heat strain in workers. Different combinations of environmental conditions can create equivalent WBGT, yet it remains unknown whether biophysical, physiological, and perceptual responses vary when working in different but equivalent hot conditions. The purpose of the study was to compare body heat storage and physiological and perceptual strain during walking in hot-dry and warm-wet conditions of the same WBGT. Twelve subjects (age: 22 ± 2 y) walked for 90 min at 60% maximum heart rate in a 27.8°C WBGT environment of hot-dry (HD: 40°C, 19% relative humidity) or warm-wet (WW: 30°C, 77% relative humidity) conditions. Partitional calorimetry was used to estimate heat storage. Core temperature at 90 min (HD: 38.5 ± 0.5°C; WW: 38.4 ± 0.3°C, p = 0.244) and cumulative heat storage (HD: 115 ± 531 Kj; WW: 333 ± 269 Kj, p = 0.242) were not different. At 90 min, heart rate was not different (HD: 160 ± 19 bpm; WW: 154 ± 15 bpm, p = 0.149) but skin temperature (HD: 36.6 ± 0.9°C; WW: 34.7 ± 0.6°C, p < 0.001), thirst (HD: 6.8 a.u.; WW: 5.3 a.u. p = 0.043), and sweat rate (HD: 15.1 ± 4.4 g·min−1; WW: 10.0 ± 4.1 g·min−1, p < 0.001) were greater in HD compared to WW. Hot environments of equivalent 27.8°C WBGT created equivalent core temperature despite differences in physiological strain during exercise, including earlier onset of cardiovascular strain, greater sweat rate, and higher skin temperature compared to a WW environment. ClinicalTrials.gov ID NCT04624919.

The SRG/eROSITA All-Sky Survey

Galaxy cluster gas temperatures (T) play a crucial role in many cosmological and astrophysical studies. However, it has been shown that T measurements can significantly vary between different X-ray telescopes. These T biases can propagate to several cluster applications in which T can be used, such as measuring hydrostatic cluster masses and constraining the angular variation of cosmological parameters. Thus, it is important to accurately cross-calibrate X-ray instruments to account for systematic biases. In this work, we present the cross-calibration between Spectrum Roentgen Gamma/eROSITA (SRG/eROSITA) and Chandra/ACIS and between SRG/eROSITA and XMM-Newton/EPIC using for the first time a large sample of galaxy cluster T. To do so, we used the first eROSITA All-Sky Survey data and the preliminary extremely expanded HIgh FLUx Galaxy Cluster Sample, a large X-ray flux-limited cluster catalog. We spectroscopically measured X-ray T for 186 independent cluster regions with both SRG/eROSITA and Chandra/ACIS in a self-consistent way for three energy bands: 0.7–7 keV (full), 0.5–4 keV (soft), and 1.5–7 keV (hard). We did the same with SRG/eROSITA and XMM-Newton/EPIC for 71 different cluster regions and all three bands. We find that SRG/eROSITA measures systematically lower T than the other two instruments, with hotter clusters deviating more than cooler ones. For the full band, SRG/eROSITA returns 20% and 14% lower T than Chandra/ACIS and XMM-Newton/EPIC, respectively, when the two other instruments each measure kBT ≈ 3 keV. The discrepancy respectively increases to 38% and 32% when Chandra/ACIS and XMM-Newton/EPIC each measure kBT ≈ 10 keV. On the other hand, the discrepancy becomes milder for low-T galaxy groups. Moreover, a broken power law fit demonstrated that there is a break at the SRG/eROSITA-Chandra/ACIS scaling relation at kBT ≈ 1.7 − 2.7 keV, depending on the energy band. The soft band shows a marginally lower discrepancy compared to the full band. In the hard band, the cross-calibration of SRG/eROSITA and the other instruments show very strong differences. We tested several possible systematic biases (such as multiphase cluster gas, Galactic absorption, non-Gaussian scatter, and selection effects) to identify the reason behind the cross-calibration discrepancies, but none could significantly alleviate the tension. For now, it is most likely that the systematically lower SRG/eROSITA T can be attributed to systematic effective area calibration uncertainties; however, the exact role of multiphase cluster gas in the observed T discrepancies needs to be further investigated. Furthermore, we provide conversion factors between SRG/eROSITA, Chandra/ACIS, and XMM-Newton/EPIC T that will be beneficial for future cluster studies that combine SRG/eROSITA T with data from other X-ray instruments. Finally, we also provide conversion functions between the official eRASS1 cluster catalog T and the equivalent core and core-excised Chandra/ACIS and XMM-Newton/EPIC T.

Crack growth in sandwich-structured foam core graphite epoxy laminate composite using a phase-field modelling approach

The laminated sandwich composites have wide structure-making applications in the automotive and aviation fields due to their lightweight and superior flexural rigidity properties. Making grooves or holes to assemble more than one structure induces crack discontinuities near the stress concentration region in these sandwich structures. The present work examines the effect of crack discontinuities on the mechanical performance and failure process of the sandwich structures under different loading conditions. Phase field method (PFM) has been presented and implemented using in-house developed MATLAB code. The effect of holes, multiple cracks, number of cores, and loading conditions are analyzed for the mechanical and fracture behavior of the structure. Load-carrying capacity, threshold displacement value for crack initiation, crack propagation trajectory, and energy absorption capacity are compared for various crack discontinuities under different loading conditions. Approximately 35% increase in load carrying capacity is observed in equivalent multiple core sandwich structures.

Core Hole Effect to Valence Excitations: Tracking and Visualizing the Same Excitation in XPS Shake-Up Satellites and UV Absorption Spectra.

Introducing a core hole significantly alters the electronic structure of a molecule, and various X-ray spectroscopy techniques are available for probing the valence electronic structure in the presence of a core hole. In this study, we visually demonstrate the influence of a core hole on valence excitations by computing the ultraviolet absorption spectra and the shake-up satellites in X-ray photoelectron spectra for pyrrole, furan, and thiophene, as complemented by the natural transition orbital (NTO) analysis over transitions with and without a core hole. Employing equivalent core hole time-dependent density functional theory (ECH-TDDFT) and TDDFT methods, we achieved balanced accuracy in both spectra for reliable comparative analysis. We tracked the same involved valence transition in both spectra, offering a vivid illustration of the core hole effect via the change in corresponding particle NTOs introduced by a 1s core hole on a Cα, Cβ, or O atom. Our analysis deepens the understanding of the core hole effect on valence transitions, a phenomenon ubiquitously observed in general X-ray spectroscopic analyses.

Buckling load optimization of sandwich plates with trapezoidal corrugated core and elliptical cutout using vibration correlation techniques and artificial neural network; experimental and numerical analysis

The present research was carried out in order to estimate the buckling load of a sandwich plate with a trapezoidal corrugated core with cut-out using three vibration correlation techniques (VCT). The structure investigated in this research is a sandwich plate with a trapezoidal core and an oval cut-out, which is made of thermoplastic polymer using a 3D printer. By using artificial neural network (ANN) and genetic algorithm (GA), the specific critical buckling load (p¯cr) which is defined as the ratio of critical buckling load (Pcr) to plate weight (gr) has been minimized and the optimal dimensions for cut-out parameters including the ratio of the large diameter of the ellipse (z=20mm) to the small diameter of the ellipse (b) and oval angles with the horizontal axis (a∘) are obtained. Using the method of equivalent properties, the trapezoidal core is transformed into an equivalent orthotropic core and finally the desired structure is transformed into a three-layer sandwich plate including homogeneous upper and lower layers and an orthotropic middle layer. By using the meshless method based on radial and polynomial functions and with the help of the finite element method, the numerical simulation of buckling and free vibration of the sandwich plate has been done. The results showed that the estimation of the buckling load with the vibration correlation technique (VCT) corresponds to the actual condition of the structure, so that due to the high quality of sandwich plate construction and its integrity, the results obtained from the first, second, and third methods of the VCT show the effectiveness of this method for predicting of the buckling load of the structure.

A pilot study on gamified and conventional e-quizzes reinforcing human histology among first-year medical and physiotherapy students.

The present retrospective, descriptive, and quasi-experimental study aimed to explore students' perceptions of traditional teaching combined with gamified and nongamified e-tests for postlecture reinforcement. Midterm knowledge retention and academic performance were also analyzed. The study was conducted from February 2021 to May 2022, involving a single group of first-year medical and physiotherapy students enrolled in equivalent core subjects on human histology at the University of Las Palmas de Gran Canaria (ULPGC). Lectures were supplemented with gamified Quizizz (QQ) or nongamified Moodle questionnaires (MQ) after lecture (t0) and 30 days later (t30). From 171 attendees, 162 volunteers were surveyed on their perceptions on the experience. Furthermore, 97 volunteers participated in the DOCENTIA-ULPGC survey on the students' satisfaction, and 123 participants individually answered 20 QQ and 20 MQ. Data were analyzed using the program Jamovi 2.3.24. The survey on volunteers' perception comprised 11 Likert items and 3 numerical scale items. The former showed acceptable internal consistency (ω-McDonald, 0.70) and validity (KMO, 0.58). Both types of e-questionnaires facilitated learning and motivated pre-reading contents but QQs were preferred. Reinforced lectures were rated higher than those unreinforced. Volunteers expressed higher overall satisfaction though DOCENTIA-ULPGC survey than the prepandemic control group. Average scores peaked at t0 with higher MQ rates. At t30, MQ and QQ scores were acceptable and similar. Participants' outcomes in the final exam tended to improve compared to the prepandemic control group, but without statistical significance. In summary, gamified and nongamified e-quizzes enhanced the student satisfaction and motivation and facilitated midterm knowledge retention.

Improved analytic method for outrigger structures considering floor stiffness

SummaryCurrent analytical models for outrigger structures in super high‐rise buildings tend to oversimplify by not considering the stiffness of individual floors. This paper introduces a more refined calculation model, based on the substructure method, which takes floor stiffness into account. To verify our proposed approach, we derived a mathematical algorithm and developed a finite element model using ANSYS. When compared to traditional methods that only account for outrigger stiffness, our model, which incorporates both outrigger and floor stiffness, provides improved accuracy in calculating vertex displacement. It also suggests an upward shift in the optimal position for the outrigger and bolsters the overall building's lateral stiffness. To further our analysis, we introduced an equivalent stiffness calculation formula, using the Bayesian parameter estimation method. When applied to dynamic analysis, this formula aligns closely with the results from the finite element simulations. Furthermore, the suggested algorithm for determining the best position for the outrigger is consistent with theoretical calculations. By considering the contribution of regular floors to the overall structure, we found that the fitted equivalent core tube stiffness offers a reliable reflection of structural stiffness. Lastly, when this equivalent stiffness was applied to a dynamic analysis based on Rayleigh's energy method, there was a noticeable reduction in computational effort. This yields not only more efficient calculations but also precise results, rendering it particularly valuable during the initial design phases of high‐rise buildings.

Underwater impulsive response of sandwich structure with multilayer foam core

Abstract The coupling between fluid-solid interaction and structural response is a crucial factor in understanding the resistance of sandwich structures to underwater blasts. In this study, we present a theoretical model that predicts the dynamic response of multilayer foam core sandwich beams subjected to underwater impulses. We carried out a time-scale intercoupling analysis by considering the compressible core in both incident impulse and structural response. In the incident impulse coupling phase, the one-dimensional fluid-structure interaction in terms of cavitation evolution is conducted to obtain the incident pressure profile. A four inter-stages response model is proposed for further analyze the structural response coupling phase and its coupling with core strength. Explicit finite element calculations are performed to verify the theoretical results in terms of the velocity profile, transverse deflection, and core compression. The results suggest that the interaction between the four stages of the dynamic response is significantly influenced by the impulsive intensity and core strength, and the sandwich beam does not undergo all the four stages. The equivalent core strength used in the theoretical analysis is confirmed accurate to predicts impact resistance of the corresponding graded core sandwich beam, which is inferior to the sandwich beam with uniform cores, despite having the same areal mass.

Equivalent mechanical property calculation method of mini-channels in printed circuit heat exchanger

Printed circuit heat exchanger (PCHE) is a critical component to transfer heat from the primary loop to the secondary loop in supercritical carbon dioxide (SCO2) Brayton cycle system used for Generation IV nuclear reactors. The PCHE is operated at high temperature and high pressure, and thus the thermo-mechanical analysis is essential to its structural safety. However, it is difficult to directly model the whole PCHE by the finite element method because the PCHE is composed of large amounts of mini-channels. The simplified approach based on equivalent-homogeneous-solid concept was used by many researchers, but accurate method to calculate the equivalent mechanical properties of PCHE mini-channels is lacking. In this paper, an asymptotic homogenization method is proposed to calculate the equivalent mechanical properties of PCHE mini-channels. Firstly, the periodicity of mini-channels is considered as a small parameter, and the statement of equivalent elasticity matrix of mini-channels is derived in the form of stain energy of the unit cells. Secondly, numerical implementation of asymptotic homogenization method for a unit cell in the PCHE mini-channels is conducted. The equivalent Young’s modulus, Poisson’s ratio and shear modulus of mini-channels are fitted as functions of temperature. Finally, the thermo-mechanical performance of the equivalent PCHE core model is compared with the actual model. The results show that the maximum deviations in mechanical and thermal deformations between the equivalent and actual PCHE core models are less than 2.4% and 1% respectively. However, the computation time of the equivalent model is a factor of 45–190 below the value of actual model.

Experimental and Computational Study of Enhanced Forced Convection Heat Transfer in Novel Slotted Wavy-Plate-Fin Channels

Abstract Forced convective enhanced heat transfer performance of airflows (50 ≤ Re ≤ 4000, Pr ∼ 0.71) in novel slotted sinusoidal wavy-plate-fins is investigated both experimentally and computationally. The slotted wavy fin core evaluated in the experiments was produced by direct metal laser sintering (DMLS). Compared with the equivalent or nonslotted wavy fin core, also produced by DMLS, while the heat transfer was found to be similar, the pressure drop was reduced by as much as 31%. This very attractively significant enhancement was further explored in a three-dimensional computational analysis. Besides validating experimental results, it is seen that a significant part of pressure loss in plain wavy-fin channels is due to form drag induced by flow recirculation in the trough region. This is shown to be reduced substantially if the fins are slotted at large form drag locations. Their position and size, characterized, respectively, by phase angle (β) and dimensionless slot size (δ), are varied in the simulations to explore their role in the enhanced thermal-hydrodynamic performance. One such modified design exhibits a characteristically unusual performance at low Re, where improvement in heat transfer (+17%) is accompanied by a reduction in pressure loss (–16.8%). Additionally, at high Re, though a slight decline in heat transfer (–7.6%) is evidenced, the pressure drop is nearly cut in half (–46.6%). Moreover, the overall thermal-hydrodynamic performance based on the metric of fixed heat transfer rate and pressure drop constraint shows that ∼15% reduction in the required heat transfer surface area can be achieved with slotted wavy fins.

Power loss minimization assessment of a doubly fed induction generator with variable core resistance for wind turbines operation

&lt;p class="Default"&gt;This paper assesses the efficiency level and power loss minimization of a doubly fed induction generator (DFIG). A modified DFIG equivalent circuit with multi-core resistance connected in parallel was adopted. State-space differential equations of the DFIG was developed incorporating iron and copper loss components while a minimum flux linkage that aids in the minimization of the overall losses was derived. Simulation results showed that losses were minimized when the equivalent core resistances were connected in parallel with minimum permissible current flow. The results obtained during a transient disturbance showed that at different core resistance values of Rfe = 0.75Ω and 0.25Ω, different efficiency values of 83.45% and 41.21% were realized. An unconstrained optimization test carried out on the DFIG variable parameters showed that the DFIG power loss model was controllable with a positive definite value of 691.9801 and 2.9156〖e〗^(+5) for the leading principal determinants of the Hessian matrix. All simulation processes were achieved in MATLAB/Simulink 2020.&lt;/p&gt;

Real-time temperature field recovery of a heterogeneous reactor based on the results of calculations in a homogeneous core

Advanced pressurized water reactors are the main part of a new generation of nuclear power plant projects under development that provide cost-effective power production for various needs (Yemelyanov et al. 1982, Klimov 2002, Boyko et al. 2005, Baklushin 2011, Bays et al. 2019, Nuclear Technology Review 2019). The innovative technologies are aimed at improving the safety and reliability as well as at reducing the cost of NPPs. At the same time, improvements in design, technological and layout solutions are focused primarily on the reactor core. Assessments of the efficiency of these improvements are preceded by numerical simulations of the processes in the core, in particular heat generation and sink, with account for the difference between the study object and the standard version tested in operational practice. The authors of the article propose a method for calculating the temperature field in the core of a heterogeneous reactor (using the example of a pressurized water reactor), which makes it possible to quickly assess the level of temperature safety of various changes in the core and has the necessary speed for analyzing transients in real time. This method is based on the energy equation for an equivalent homogeneous core in the form of a heat equation that takes into account the main features of the simulated heterogeneous structure. The procedure for recovering the temperature field of a heterogeneous reactor uses the analytical relation obtained in this work for the heat sink function, taking into account inter-fuel element heat leakage losses. Calculations of temperature fields in the model of the PWR type reactor (The Westinghouse Pressurized Water Reactor Nuclear Plant 1984) were carried out in stationary and transient operating modes. The calculation results were compared with the results of CFD simulation. The area of competing use of the temperature field recovery method was indicated.

Compressive Strength Assessment of Normal and Self-Compacting Concrete Made with Recycled Coarse Aggregate Using In-Situ Tests

There is an increasing trend in construction for using recycled coarse aggregate (RCA) concrete, which is a more sustainable approach for reducing natural resource consumption. One typical method for developing more environmentally friendly structures is to partially substitute natural aggregate. limited studies investigated the use of in-situ tests to assess the compressive strength of concrete made with RCAs. In this study, ultrasonic pulse velocity (UPV) and core sampling (CST) tests were used to evaluate the compressive strength of normal vibrated (NVC) and self-compacting (SCC) concretes made with recycled coarse aggregates (RCAs). Four different compressive strengths ranging from 25 to 55 MPa were adopted for each concrete type to consider the effect of replacing 0, 20%, 40%, 60%, 80%, and 100% of the required natural coarse aggregates (NCAs) with (RCAs). Exponential relationships were adopted to relate the UPV values with the compressive strength for both RCA-NVC and RCA-SCC. Also, suggested factors were adopted to correct equivalent core strengths for both RCA-NVC and RCA-SCC. The results of both test methods (UPV) and (CST) showed good correlations to estimate the compressive strength of RCA-NVC and RCA-SCC with confidence limits of 93%.

Size effect of composite Kagome honeycomb sandwich structure reinforced with PMI foams under quasi-static bending: Experiment tests and numerical analysis

Polymethacrylimide (PMI) foams reinforced composite Kagome honeycomb sandwich structures (PKCSSs) are a new class of structure with great application potential in aerospace and navy. They have the advantages of convenient processing, low production cost, and high modulus and strength with light weight. In this paper, five PKCSS specimens with different sizes were fabricated and the size effect was studied through three-point bending (TPB) tests. By analyzing unit cell structures, theoretical models were established for PKCSS equivalent bending stiffness and core density. Combining bending failure theory of sandwich structures, PKCSS bending failure equation was derived. It was witnessed that experimental results were highly consistent with those obtained from the theoretical model. Relationships among equivalent modulus, core density, rib width, node spacing, and rib angle were also studied. Factors affecting the ultimate bending strength of PKCSS were analyzed and critical strength surface and corresponding failure mode maps were determined. This study revealed the effect of structural size on the bending characteristics of PKCSS, discussed the change rule of PKCSS bending strength and stiffness, and determined the optimal size design ratio and design suggestions.

Competency assessment for community health nurses: a focus group expert panel discussion

BackgroundGeneral Practice setting in the Primary Health Care Services are the utmost visited by the public. It is important that the nurses’ competencies in this area be assessed to ensure provision of safe and quality services.Aim/objectiveTo explore perceptions and experiences of competencies assessment tool for community health nurses working at the General Practice setting in the Primary Health Care Services.MethodsAn exploratory qualitative study utilizing focus group discussions were conducted on purposive sample of 12 officers with expertise in competency assessment and community health nursing from higher nursing education institutions, the Nursing Training and Development Centre, the Nursing Board and the Community Health Nursing Services in Brunei Darussalam. The existing competencies assessment tool was revised, the participants were divided into two groups of expert panel review team and two focus group discussions were held with each team. The focus group discussions encompassed components and methods of assessment; methods of grading; and overall organization and structure of the revised competency assessment tool.FindingsFour themes emerged: 1) International equivalent core competencies components; 2) Multi-methods approach to assessment; 3) Definitive guidelines as framework for assessment; and 4) Understanding and acceptability of the competency assessment tool.Conclusions/implications to practiceThe expert panel reviews provide practical input that were inculcated in the preliminary developed competencies assessment tool. Identification of eligible assessors were recommended based on standardized criteria, and socialization and training held to set direction and guidance for implementing the utilization of the competencies assessment tool. Further studies are deemed important to critically evaluate and validate the preliminary competencies assessment tool for development of a more robust assessment instrument.

Magnetic Performance Improvement Caused by Tensile Stress in Equivalent Iron Core Fabricated by High-Strength Non-Oriented Electrical Steel

This article presents the application of high-strength non-grain-oriented (NGO) silicon steel in the design of the rotor topology of a high-speed interior permanent magnet synchronous machine (IPMSM). By narrowing the magnetic bridges and center posts in the rotor, the purpose of reducing leakage flux and increasing output torque is achieved. Narrower magnetic bridge will cause electromagnetic loss concentration and tensile stress concentration, and tensile stress can effectively weaken the core loss at the part where the iron loss is concentrated. The high-strength NGO silicon steel used in this article is SW35YS600. This high-strength NGO adopts the method of increasing dislocations density to achieve the goal of increasing the structural strength while taking into account the electromagnetic properties at the same time. The electromagnetic properties of this high-strength NGO are less sensitive to tensile stress. As the frequency increases, the improvement of tensile stress on iron loss increases. However, after this material undergoes stress relief annealing, its electromagnetic and mechanical properties deteriorate significantly. Observing the grain structure, it was found that the grains of the high-strength NGO increased significantly after annealing.

Method to Generate Random Element Equivalent Core Models Based on the NMR T 2 Spectrum for Waterflooding in Tight Sandstone.

Numerical simulation based on the widely used homogeneous equivalent core model can solve the problem of high cost and long duration of coreflooding experiments. However, using the homogeneous equivalent core model, it is difficult to reflect the characteristics of the core interior during waterflooding. In this paper, we provide a method to generate random element equivalent core models based on the nuclear magnetic resonance (NMR) T2 spectrum, and it can divide permeability regions by granularity. The permeability calculation formula derived from the complementary correlation principle ensures that most areas of the core satisfy the correlation between permeability and T2 relaxation time. Moreover, the generation method can guarantee that the random element equivalent core model is consistent with the homogeneous equivalent core model in terms of the geometric mean of permeability. The simulation results show that the high-resolution random element equivalent core model can better simulate microcosmic fingering inside the core during waterflooding. Nevertheless, the proposed method has some limitations emanating from the demarcation criteria and the porosity assumption. Furthermore, the generation method is expected to be extended to simulate enhanced oil recovery (EOR) mechanisms on the core scale after waterflooding.

SMART ALGORITHM FOR INTERVAL ESTIMATION OF ARC-QUENCHING REACTOR PARAMETERS

The purpose of the arc suppression reactor is to reduce the capacitive current of the network to a safe level where the single-phase earth fault current at the fault location does not exceed five amperes. The current reduced to a permissible level prevents open arcing at the fault location. For proper operation of this device, the arc suppression reactor control automatics needs to adjust the zero-sequence circuit to resonance, which balances the capacitive current of the mains and the inductive current of the reactor. To perform this tuning, it is not necessary to have information about the absolute values of the parameters of the zero-sequence circuit, but by determining them, the automation device is able to solve a wider range of tasks related to network diagnostics and increasing the efficiency of the arc suppression reactor. In this article we consider an approach to solving the problem of parametric identification of arc suppression reactor using the method of interval estimation of object parameters. The information about the operation modes of the arc suppression reactor is obtained by means of a simulation model of the object. Using the observed values, the object parameters are obtained by use of the inverse function to the simulation model. The dependence of the object parameters on the observed parameters is approximated using upper and lower parameter estimation models. The quantile regression method was applied to tune the estimation models. The need to increase the generalization ability of the algorithm is revealed. The method of adjustment of parameters of regularization of learning process to increase generalization ability of algorithm without increase of informativity of data in a training sample is offered. The results of algorithm performance are presented on the example of magnetization branch parameters estimation of arc suppression reactor. The boundaries of the interval of equivalent magnetic core loss resistance and magnetizing inductance are obtained. The limitations of the methods are analyzed, and recommendations for improving the quality of the algorithms are given.

Plastic Forming of Sandwich Panels and Numerical Analyses of the Forming Processes Based on Elastoplastic Equivalent Model.

This paper studies the plastic forming of sandwich panels and proposes a universal elastoplastic equivalent method suitable for sandwich panels. To verify the generality of the equivalent method, according to the different core structures, the cores of bi-directional trapezoidal sandwich (BTS) panels and aluminum foam sandwich (AFS) panels are equated to orthotropic and isotropic (special orthotropic) single-layer panels respectively. Through the finite element (FE) numerical simulation of the mesoscopic model of the sandwich panel, the elastoplastic constitutive relationship of the equivalent core model is established, and then the macroscopic equivalent model of the sandwich panel is established. The FE numerical simulation of plastic forming was carried out for the mesoscopic model and equivalent model of BTS panel and AFS panel, and plastic forming experiments were conducted for the sandwich panel through a multi-point forming (MPF) test machine. The results show that the relative errors of the section average stress at the same position of the equivalent model and the mesoscopic model of sandwich panels are all within 4%; compared with the experimental results, the equivalent model of the sandwich panel has high forming accuracy and small shape error, which verifies the high accuracy and generality of the equivalent method. Moreover, using the sandwich panel equivalent model effectively reduces the calculation time of the numerical simulation.

Analytical gradients for core-excited states in the algebraic diagrammatic construction (ADC) framework.

Expressions for analytical molecular gradients of core-excited states have been derived and implemented for the hierarchy of algebraic diagrammatic construction (ADC) methods up to extended second-order within the core-valence separation (CVS) approximation. We illustrate the use of CVS-ADC gradients by determining relaxed core-excited state potential energy surfaces and optimized geometries for water, formic acid, and benzene. For water, our results show that in the dissociative lowest core-excited state, a linear configuration is preferred. For formic acid, we find that the O K-edge lowest core-excited state is non-planar, a fact that is not captured by the equivalent core approximation where the core-excited atom with its hole is replaced by the "Z + 1" neighboring atom in the periodic table. For benzene, the core-excited state gradients are presented along the Jahn-Teller distorted geometry of the 1s → π* excited state. Our development may pave a new path to studying the dynamics of molecules in their core-excited states.