Equivalent Sections Research Articles

Carbon-isotope stratigraphy of the Lower Cambrian (Cambrian explosion) in northwestern Yangtze Platform, China: Implications for global correlation

The Archaeocyathid Extinction Carbon Isotope Excursion (AECE) and Mingxinsi Carbon Isotope Excursion (MICE) are major events in the Early Cambrian sedimentary records but controversially heterogeneous in their magnitudes, as well as local and global correlations. This paper presents a high-resolution δ13Ccarb profile from the Shiliu section in the western Yangtze Platform (China) that spans the lower part of the Lower Cambrian. The investigated Lower Tianheban interval (∼110 m) is dominated by marine carbonates (lime mudstones) alternating occasionally with thinly-bedded black shale and mudstone interbeds. The investigated micritic carbonates were examined through a multi-technique protocol, combining petrographic and geochemical assessments, to evaluate the degree of sample preservation. The δ13Ccarb values (−2.4‰–1.8‰) show an insignificant correlation with the δ18Ocarb values (−12.6‰ to −8.7‰, R2 = 0.012), the Mn/Sr ratios (R2 = 0.001), and Al concentrations (R2 = 0.041). This supports the preservation of predominantly at least near-primary δ13Ccarb signatures, which can be utilized to reconstruct a reliable, high-resolution δ13Ccarb profile for chemostratigraphic correlations in the area and beyond. The profile displays a lower positive excursion of ∼3‰ overlain immediately by a negative excursion of ∼2.3‰. The archaeocyath zonation scheme suggests that the lower excursion is correlated with the global MICE event and the upper excursion with the AECE event. The results provide an alternative option for interpreting the carbon isotope excursions in the Lower Cambrian within the Yangtze Platform as well as other equivalent sections at a global scale.

Nuclear-structure experiments at iThemba LABS to investigate discrepancies between (p, p′) and (γ, xn) data

The iThemba Laboratory for Accelerator Based Sciences (iThemba LABS) is a centre of expertise and innovation in the field of nuclear-structure physics and is a leader in several high-impact studies. One of the highlights of these nuclear-structure experiments is the study of the broad structure of the IsoVector Giant Dipole Resonance (IVGDR) in the rare-earth region. Proton inelastic scattering experiments with Ep = 200 MeV were performed on the even-even Nd isotope chain and 152Sm at very forward scattering angles including zero degrees with the K600 magnetic spectrometer. The evolution of the shape of the IVGDR in the transition from spherical to deformed nuclei was investigated. One of the goals of this highlighted study was to confirm the K-splitting observed in previous photo-absorption measurements from Saclay. Significant discrepancies were found between the direct (γ, xn) data obtained at Saclay and the equivalent photo-absorption cross sections obtained using (p, p′) data from the K600. Furthermore, discrepancies exist for several nuclei between photo-absorption data taken at the Saclay and Livermore laboratories. These discrepancies, possible reasons for them and future investigations will be presented and discussed.

Эквивалентирование участков электроэнергетических систем на основе режимных параметров в узлах эквивалентирования

When modeling steady-state and transient operating modes in electric power systems, it is necessary to determine a section of the electrical network to simplify the processes occurring in the area not covered by equivalenting. In this case, it is necessary to identify equivalents and relationships with respect to the speci-fied section. The purpose of the research is to determine the parameters of the equivalent sections of power systems and their relationships with respect to the given nodes. Methods of mathematical modeling of the elements of power systems, methods of the theory of electric circuits, and methods of matrix analysis are used. To verify the results, electrical circuits of existing power systems and the software package “Auto-mated Workplace of Relay Protection and Automation Service” have been applied. The implementation of the algorithm is carried out using programming in the Python environment. An algorithm to determine the parameters of equivalent circuits of positive, negative and zero sequences is developed and tested when solving the problem of equivalenting a network section with respect to given nodes. Comparison of the levels of currents in case of short circuits according to the developed algorithm and the software package “Automated Workplace of Relay Protection and Automation Service” in the equivalent nodes shows the high accuracy of the equivalent results in accordance with the developed algorithm. The algorithm considers transformer connections when equivalenting with respect to the nodes located at different voltage classes, as well as phase shifts caused by the star-delta conversion.

Assessment of greenhouse emissions of the green bean through the static enclosure technique

Urban green installations are extensively promoted to increase sustainable and accessible food production and simultaneously improve the environmental performance and liveability of city buildings. In addition to the multiple benefits of plant retrofitting, these installations may lead to a consistent increase in biogenic volatile organic compounds (BVOCs) in the urban environment, especially indoors. Accordingly, health concerns could limit the implementation of building-integrated agriculture. In a building-integrated rooftop greenhouse (i-RTG), throughout the whole hydroponic cycle, green bean emissions were dynamically collected in a static enclosure. Four representative BVOCs, α-pinene (monoterpene), β-caryophyllene (sesquiterpene), linalool (oxygenated monoterpene) and cis-3-hexenol (LOX derivate), were investigated in the samples collected from two equivalent sections of a static enclosure, one empty and one occupied by the i-RTG plants, to estimate the volatile emission factor (EF). Throughout the season, extremely variable BVOC levels between 0.04 and 5.36 ppb were found with occasional but not significant (P > 0.05) variations between the two sections. The highest emission rates were observed during plant vegetative development, with EFs equivalent to 78.97, 75.85 and 51.34 ng g−1 h−1 for cis-3-hexenol, α-pinene, and linalool, respectively; at plant maturity, all volatiles were either close to the LLOQ (lowest limit of quantitation) or not detected. Consistent with previous studies significant relationships (r ≥ 0.92; P < 0.05) were individuated within volatiles and temperature and relative humidity of the sections. However, correlations were all negative and were mainly attributed to the relevant effect of the enclosure on the final sampling conditions. Overall, levels found were at least 15 folds lower than the given Risk and LCI values of the EU-LCI protocol for indoor environments, suggesting low BVOC exposure in the i-RTG. Statistical outcomes demonstrated the applicability of the static enclosure technique for fast BVOC emissions survey inside green retrofitted spaces. However, providing high sampling performance over entire BVOCs collection is recommended to reduce sampling error and incorrect estimation of the emissions.

Shear buckling coefficients of web panels for composite girders considering flange-web stiffness ratio

Designing a web panel for composite girders necessitates an accurate evaluation of the shear buckling strength. However, the current design specifications calculate the strength of web panels for composite girders conservatively. Additionally, its rational determination is missing in existing studies. This study investigates the shear buckling coefficients of composite girders through numerical analysis. The numerical analysis model assumes that the concrete slab fully restrains the web panel. In addition, the concrete slab of the composite girders in the numerical analysis model is replaced by equivalent top flange sections using a transformed thickness according to the modular ratio (n) of the concrete and steel. Additionally, the stiffness of the bottom flange and web panel is parameterized to evaluate the effect of their relative stiffness on the critical shear buckling strength of the web panel. The results show that the relative stiffness of the flange and web panel significantly affects the shear buckling coefficient. To determine the shear buckling coefficient by reflecting these structural characteristics, the relative stiffness is defined as the ratio of the torsional stiffness of the flange to the flexural stiffness of the web panel. The proposed formulas for the shear buckling coefficient of web panels for composite girders correlate well with the numerical analysis results. Since the accurate shear buckling strength can be derived from these formulas, the web panel for composite girders can be designed more accurately and economically.

Assessment of Asphalt Mixture Disk-Shaped Compact Tension Test Indexes for Reflective Cracking Performance

Abstract Disk-shaped compact tension (DCT) testing is a commonly used low-temperature fracture test to determine the cracking resistance of asphalt mixtures. The current testing specification only considers the fracture energy (Gf) from load-crack mouth opening displacement test data. However, Gf does not directly take into consideration the behavior of the post peak region of the curve, which may indicate the mixture’s ability to resist crack propagation and provide insight into fracture processes (e.g., crack growth velocity). It is possible to have two DCT specimens with similar Gf values but dramatically different load-displacement responses. The main focus of this paper is to make a comparative evaluation of various performance indexes developed for DCT fracture testing with respect to field reflective cracking performance of 10 full-scale asphalt concrete overlay test sections. This study evaluates Gf in addition to three other indexes: fracture strain tolerance (FST), rate-dependent cracking index (RDCI) and a proposed DCTIndex from Minnesota Department of Transportation that considers the post peak load-displacement behavior. An equivalent performance index approach is adopted to make comparisons of test sections with varying overlay structures in terms of thickness and material properties. Results from this study showed there was relatively good agreement between all equivalent laboratory performance indexes in identifying the best and worst performing overlay sections, according to normalized field performance indexes after approximately three years of service. In general, the equivalent FST and RDCI laboratory indexes rank test sections similarly, while equivalent Gf and DCTIndex have comparable ranking.

Adaptation and feasibility of the online version of the Fugl Meyer scale for the assessment of patients following cerebrovascular accidents

Patients who have suffered a chronic cerebrovascular accident or a stroke need long-term physiotherapy treatments. However, they have had to be stopped due to the COVID-19 pandemic. To be able to offer these patients an online functional assessment, a proposal was put forward to design an adaptation of the Spanish version of the Fugl Meyer assessment scale and to test its viability. The adapted online scale, based on the Fugl Meyer assessment scale. The motor function, balance and pain domains were kept, and items requiring assistance for the patient were removed. This scale was administered to 13 patients with a chronic cerebrovascular accident from the Salamanca Acquired Brain Injury Association (Asociacion de Dano Cerebral Adquirido) via different web platforms. The procedure followed was the same as for the original scale and lasted from 30 to 45 minutes. All the patients completed the Fugl Meyer assessment scale, online version. The greatest difficulty was encountered in the assessment of the lower limbs. Patients and physiotherapists highlighted how easy it was to complete the items in the scale. On comparing the versions, statistically significant positive correlations were found with the original version (p < 0.001) and the correlation coefficients indicated a strong association. The difference between the equivalent sections of the scale in each instrument was no greater than 5%, except for balance. The Fugl Meyer assessment scale, online version, is a feasible, useful and easy to apply scale that allows assessment of the functional status of stroke patients and can help meet the current needs during the COVID-19 pandemic.

Structural Testing and Design of Wire Arc Additively Manufactured Square Hollow Sections

Wire arc additive manufacturing (WAAM) is a method of metal three-dimensional (3D) printing that has the potential for a significant impact on the construction industry due to its ability to produce large parts with reasonable printing times and costs. However, there is currently a lack of fundamental data on the performance of structural elements produced using this method of manufacturing. Seeking to bridge this gap, the compressive behavior and resistance of WAAM square hollow sections (SHS) are investigated in this paper. In a previous study by the authors, testing reported of sheet material produced in the same manner as the studied SHS is first summarized. The production, measurement, and testing of a series of stainless steel SHS stub columns are then described. Regular cross-section profiles were chosen to isolate the influence of 3D printing and enable direct comparisons to be made against equivalent sections produced using traditional methods of manufacturing. A range of cross-section sizes and thicknesses were considered to achieve variations in the local cross-sectional slenderness of the tested specimens, allowing the influence of local buckling to be assessed. Repeat tests enabled the variability in response between specimens to be evaluated; a total of 14 SHS stub columns of seven different local slendernesses was tested, covering all cross-section classes of AISC 370 and Eurocode 3. Advanced noncontact measurement techniques were employed to determine the as-built geometric properties, while digital image correlation measurements were used to provide detailed insight into the deformation characteristics of the test specimens. Owing to the higher geometric variability of WAAM relative to conventional forming processes, the tested 3D printed stub columns were found to exhibit more variable capacities between repeat specimens than is generally displayed by stainless steel SHS. Comparisons of the stub column test results with existing structural design rules highlight the need to allow for the weakening effect of the geometric undulations that are inherent to the WAAM process in order to achieve safe-sided strength predictions.

Image-to-Images Translation for Multiple Virtual Histological Staining of Unlabeled Human Carotid Atherosclerotic Tissue.

Histological analysis of human carotid atherosclerotic plaques is critical in understanding atherosclerosis biology and developing effective plaque prevention and treatment for ischemic stroke. However, the histological staining process is laborious, tedious, variable, and destructive to the highly valuable atheroma tissue obtained from patients. We proposed a deep learning-based method to simultaneously transfer bright-field microscopic images of unlabeled tissue sections into equivalent multiple sections of the same samples that are virtually stained. Using a pix2pix model, we trained a generative adversarial neural network to achieve image-to-images translation of multiple stains, including hematoxylin and eosin (H&E), picrosirius red (PSR), and Verhoeff van Gieson (EVG) stains. The quantification of evaluation metrics indicated that the proposed approach achieved the best performance in comparison with other state-of-the-art methods. Further blind evaluation by board-certified pathologists demonstrated that the multiple virtual stains have high consistency with standard histological stains. The proposed approach also indicated that the generated histopathological features of atherosclerotic plaques, such as the necrotic core, neovascularization, cholesterol crystals, collagen, and elastic fibers, are optimally matched with those of standard histological stains. The proposed approach allows for the virtual staining of unlabeled human carotid plaque tissue images with multiple types of stains. In addition, it identifies the histopathological features of atherosclerotic plaques in the same tissue sample, which could facilitate the development of personalized prevention and other interventional treatments for carotid atherosclerosis.

Experimental investigations of the flexural‐torsional buckling resistance: Steel rolled I‐section beam‐columns under moment gradient

AbstractBeam‐columns of uniform rolled or equivalent welded sections are the member types most commonly used in steel skeletal structures. EN1993‐1‐1 [1] provides two design procedures of such members, one based on the interaction equations for the section resistance and the member buckling resistance, and the other one based on the so‐called General Method (GM) that tends to follow that of Ayrton‐Perry's procedure used for extreme cases of compression without bending and bending without compression. Above cited design procedures yield similar results when the beam‐column is predominantly under bending but sometimes results being away from each other when the beam‐column is predominantly under compression. Recently, a novel version of GM has been proposed [2], providing a tool of more rational design that yields the results from Eurocode 3 interaction equation procedure in both extreme cases. The proposed procedure is based on the Euclidean norm of dimensionless action effects and evaluation of Maquoi‐Rondal imperfection factor interpolated between those for compression without bending and bending without compression. This analytical procedure was verified with a wide range of advanced numerical simulations incorporating geometrical and material imperfections (residual stresses). In order to validate the accuracy of the proposed procedure, an experimental study on the buckling resistance of rolled I‐section beam‐columns was carried out the results of which are presented in this paper. Firstly, an overview of the experimental programme carried out on subframe specimens is given and then followed by the summary of measurements of deformations as well as global load vs. displacement characteristics for selected specimens. Finally, an assessment of the beam‐column buckling resistance, experimental vs. predicted by Eurocode 3 interaction equations procedure, is presented and conclusions with regard to the preliminary validation exercise are drawn.

Fire performance of eccentrically-loaded square and rectangular tubed-reinforced-concrete columns

Tubed-reinforced-concrete (TRC) columns are gaining increasing popularity in engineering constructions, however, research on their fire performance is still limited and mainly focused on concentrically-loaded columns. In this study, extensive numerical analysis was carried out to investigate the performance of square and rectangular TRC columns under eccentric loading and exposed to ISO 834 standard fire. A sequentially-coupled thermo-mechanical finite element analysis (FEA) model was developed in ABAQUS and validated well against fire testing results. The high-temperature overall deformations, internal bending moments and cross-sectional load redistributions of square TRC columns with different load eccentricities were analysed. Parametric studies were conducted to investigate the influences of load eccentricity ratio, sectional aspect ratio, bending direction, fire protection thickness, sectional dimension, load ratio and slenderness ratio on the fire resistance of square and rectangular TRC columns. Load eccentricity was found to have a greater effect on the fire resistances of columns of lower slenderness than those of columns of higher slenderness. Rectangular TRC columns of sectional aspect ratios no larger than 2 could generally achieve identical buckling resistance as that of the equivalent square sections. The influences of sectional aspect ratio and bending direction on the column fire resistance were insignificant. A design method was then proposed for both the ambient-temperature and high-temperature designs of eccentrically-loaded square and rectangular TRC columns. The fire design method could cover both protected and unprotected TRC columns. The design method has been thoroughly validated against detailed FEA modelling and yields excellent agreements with the modelling results.

Testing micrite as an ancient seawater Mg isotopic composition archive: A case study of Upper Paleozoic carbonate

The marine magnesium (Mg) cycle is the nexus bridging continent, ocean, and Earth's interior. River water is the only major Mg source, while carbonate precipitation and hydrothermal reaction are the two major processes removing seawater Mg from the ocean inventory. Reconstruction of the deep time marine Mg cycle can be approached with Mg isotopic composition of seawater (δ26Mgsw), because variation of δ26Mgsw may reflect the change of riverine input, carbonate precipitation or intensity of hydrothermal reaction. As the most common component of marine carbonate rocks, micrite or lime mud has been regarded as the premium material that records ancient seawater geochemical compositions and accordingly has been widely used in paleoenvironment studies. However, it is unclear whether micrite can be applied to reconstruct ancient δ26Mgsw. Because of the long residence time of seawater Mg, if micrite archives δ26Mgsw, it is predicted that δ26Mgmicrite should show limited temporal and spatial variation in a short (<1 million years) time scale. In this study, we measured δ26Mg of micrite component (δ26Mgmicrite) collected from Upper Paleozoic limestones in South China. Though δ26Mgmicrite values have limited spatial variation from the time equivalent sections, which suggests a homogeneous ancient seawater Mg isotopic composition, δ26Mgmicrite values show significant stratigraphic variations in all the studied sections. To further test whether such isotopic variations could reflect the change of δ26Mgsw, on the basis of high-resolution conodont biostratigraphic frameworks, we developed a mass balance model to quantify the marine Mg cycle. The modeling results indicate that the observed stratigraphic variations in δ26Mgmicrite cannot be explained by the fluctuation of δ26Mgsw, suggesting that extracting δ26Mgsw signal from micrite is highly complicated. Such complexity might be ascribed to: (1) multiple sources of micrite (micritization of carbonate, direct precipitation from seawater/porewater, and fragmentation of calcified algae), (2) wide ranges of Mg isotopic fractionation in carbonate precipitation (e.g., the vital effect of biogenic Ca‑carbonate precipitation), and (3) post-depositional overprinting at low Mg concentration in micrite. The findings of this study highlight the caution against simple interpretation of stratigraphic variability in δ26Mgmicrite as reflection the evolution of seawater Mg isotopic composition.

Nullor Based New Implementation of CDBA Using Current Feedback Operational Amplifier

In this paper, a methodology based on nullors and passive elements to create equivalent circuits for existing building blocks has been presented. This methodology has been used for generating the equivalent nullor circuit for Current Differencing Buffered Amplifier (CDBA) and its implementation through AD844 ICs of Current Feedback Operational Amplifier (CFOA) has been presented. The proposed circuit is further modified by replacing the equivalent nullor sections with smaller blocks. The implemented CDBA (proposed CDBA-I) has been simulated and compared with existing topologies of CDBA to represent its proper functioning using LTSPICE. The proposed CDBA configuration offers a symmetric structure for its 2 differential inputs and offers higher bandwidth. Moreover, the configuration has been modified further to achieve low noise output terminal by the use of another CFOA (proposed CDBA-II). Both of these proposed configurations have been simulated and verified experimentally.

Life and death in the Chicxulub impact crater: a record of the Paleocene–Eocene Thermal Maximum

Abstract. Thermal stress on the biosphere during the extreme warmth of the Paleocene–Eocene Thermal Maximum (PETM) was most severe at low latitudes, with sea surface temperatures at some localities exceeding the 35 ∘C at which marine organisms experience heat stress. Relatively few equivalent terrestrial sections have been identified, and the response of land plants to this extreme heat is still poorly understood. Here, we present a new record of the PETM from the peak ring of the Chicxulub impact crater that has been identified based on nannofossil biostratigraphy, an acme of the dinoflagellate genus Apectodinium, and a negative carbon isotope excursion. Geochemical and microfossil proxies show that the PETM is marked by elevated TEX86H-based sea surface temperatures (SSTs) averaging ∼37.8 ∘C, an increase in terrestrial input and surface productivity, salinity stratification, and bottom water anoxia, with biomarkers for green and purple sulfur bacteria indicative of photic zone euxinia in the early part of the event. Pollen and plants spores in this core provide the first PETM floral assemblage described from Mexico, Central America, and the northern Caribbean. The source area was a diverse coastal shrubby tropical forest with a remarkably high abundance of fungal spores, indicating humid conditions. Thus, while seafloor anoxia devastated the benthic marine biota and dinoflagellate assemblages were heat-stressed, the terrestrial plant ecosystem thrived.

Innovative sandwich-like composite biopanels – towards a new building biomaterials concept for structural applications in nonconventional building systems

ABSTRACT Redirecting the actual construction industry, which is one of the major sources of global pollution, is relevant to achieve green innovation efficiency. Researching on the potentials of wood species can lead to propose alternatives that allow reducing/reinventing conventional building materials and systems. This investigation aims to determine, evaluate and analyze the biomechanical/structural properties and performances of lightweight sandwich-like composite biopanels made of bamboo, melina and balsa. A total of 92 samples were experimentally tested under compression, bending, shear, tension, density, moisture content, glue and ply-delamination. The experimental data were validated and compensated through 82 finite element analyses. The acquired results were compared with equivalent sections of conventional materials in terms of strength, rigidity, structural behavior and mechanical efficiency. E.g. the results show the biopanels are up to two and three times more mechanically resistant than solid wall bricks and concrete block walls, respectively; and, up to nine times higher in terms of mechanical efficiency than steel. The results from the biomechanical analyses confirm the practical utilization of the wall biopanels into nonconventional building projects even as structural elements; most important, the implementation of the proposed wall biopanels into actual building systems would significantly reduce fatalities and destroyed dwellings during seismic and windy events due to its remarkable flexibility, strength and ductility.

Experimental and numerical investigation of lateral torsional buckling behavior and capacity of welded Q460 beams

Compared to normal strength steel (NSS), high strength steel (HSS) has many advantages, such as high yield strength, high tensile strength, and high structural reliability. Recently, HSS beams have gradually been employed in practical engineering. In this investigation, eight tests and parametric analysis were carried out to study the lateral torsional buckling (LTB) behavior and capacity of welded Q460 beams. An effective loading system that released the lateral constraint of the loading point was developed. Totally eight tests of welded beams with lateral restraints at two end supports were conducted under a mid-span concentrated force. Among these eight welded beams, one Q235 beam was tested to compare with seven Q460 beams. The flange width-to-thickness ratio changed from 4.6 to 9.6, the web height-to-thickness ratio changed from 28.75 to 47.50, and the beam span was varied from 3 m to 5 m. In addition, a series of parametric analyses considering initial geometric imperfections were performed to evaluate and investigate the effects of key parameters on the LTB behavior of welded Q460 beams. The experimental and numerical results were compared with the LTB curves from Chinese design codes GB50017-2017 and GB50017-201X, Australian code AS4100, and Eurocode 3. The GB50017-201X, AS4100, and Eurocode 3 for general sections underestimate their LTB capacity. The current GB50017-2017 and Eurocode 3 for rolled and equivalent welded sections are unsafe for evaluating the LTB capacity of HSS beams. Modified design equations that are more appropriate for predicting the LTB capacity of welded Q460 beams are presented.

Lateral-Torsional buckling behaviour of mono-symmetric S460 corrugated web bridge girders

A bstract Bridges around the world have utilised individually the mono-symmetric I-section corrugated web girders and the high-strength steel materials (HSSs). However, based on open database, there has not been any investigation in the literature exploring the mono-symmetric corrugated web bridge girders (CWBGs) constructed from HSSs. The paper is, therefore, devoted to numerically explore the global buckling of such girders built up from S460, which has extensively been used in bridge construction globally. This has been made based on finite element models (FEMs) developed by ABAQUS programme. Note that this paper merely considers girders having unequal flanges, but are symmetrical with regard to their minor axis, and their wider flanges are always deemed under compression. The validity of the current FEMs has not only depended on the previous experience of the authors, but also on the comparison between the elastic critical buckling moments and the available prediction methods. Additionally, experimental test results of flat-webbed girders have been considered in the validation. Parametric study has been carried out on simply supported girders considering mainly the influences of the mono-symmetry ratio and corrugation dimensions on the flexural buckling performance of the CWBGs which utilise S460 HSS. Several conclusions have been found that might aid the structural engineers in designing efficient cross-sections in the future. Additionally, the ultimate loads of the current CWBGs have been compared with EC3 specifications, and two design failure modes have been found to take place in present parametric study; the tension flange yielding and the lateral-torsional buckling (LTB) of the compression flange. The results, generally, show that the recommended method by EC3, for equivalent welded sections, is the most suitable in predicting the strengths of the current girders. Though, two modifications have been suggested for EC3 strengths regarding the tension flange yielding design formula and the LTB curve of the girders with depth-to-width ratios ≤2.0. The modified EC3 strength is generally found to provide accurate predictions for the CWBGs which utilise S460 HSS. • The flexural strength and behaviour of the mono-symmetric BGCWs is investigated. • High-strength steel is considered. • The effect of the corrugation profile is examined. • A modified EC3 design model is suggested.

Improving Secondary School Students Physics Achievement Using Reciprocal Peer Tutoring: A Multi-level Quasi-Experimental Study

Background:The purpose of this study was to test the best mix of reciprocal peer tutoring with direct teaching methods to improve students’ achievement in secondary school physics teaching in content-focused and high-stake examination-oriented curriculum.Material and methods:Data was gathered from three equivalent grade-9 sections selected based on physics achievement pre-test and assigned to three different intervention groups in pre-test post-test multi-level quasi-experimental design. The three groups used reciprocal peer tutoring once a week (N=46), twice a week (N=46) and three lessons a week (N=51) for 9 weeks and during the teaching of two physics units.Results:Results were that reciprocal peer tutoring helped in improving physics achievement of secondary school students (R2 =0.316) in favor of low achieving (P=0.001) and female (P=0.038) students when it is used as a unilateral pedagogy.Conclusions:The conclusion is that reciprocal peer tutoring used as a unitary classroom pedagogy helped all students and differentially less able and female secondary school students to enhance their physics achievement to some extent without negatively impacting their learning. Further replication research with a comparison group was recommended to find a conclusive evidence if the observed frailer of mixing pedagogy persists.

Spatially Controlled Fabrication and Mechanisms of Atomically Thin Nanowell Patterns in Bilayer WS2 Using in Situ High Temperature Electron Microscopy.

We show controlled production of atomically thin nanowells in bilayer WS2 using an in situ heating holder combined with a focused electron beam in a scanning transmission electron microscope (STEM). We systematically study the formation and evolvement mechanism involved in removing a single layer of WS2 within a bilayer region with 2 nm accuracy in location and without punching through to the other layer to create a hole. Best results are found when using a high temperature of 800 °C, because it enables thermally activated atomic migration and eliminates the interference from surface carbon contamination. We demonstrate precise control over spatial distributions with 5 nm accuracy of patterning and the width of nanowells adjustable by dose-dependent parameters. The mechanism of removing a monolayer of WS2 within a bilayer region is different than removing equivalent sections in a monolayer film due to the van der Waals interaction of the underlying remaining layer in the bilayer system that stabilizes the excess W atom stoichiometry within the edges of the nanowell structure and facilitates expansion. This study offers insights for the nanoengineering of nanowells in two-dimensional (2D) transitional metal dichalcogenides (TMDs), which could hold potential as selective traps to localize 2D reactions in molecules and ions, underpinning the broader utilization of 2D material membranes.

One-step Monte Carlo global homogenization based on RMC code

Abstract Due to the limitation of the computers, the conventional homogenization method is based on many assumptions and approximations, and some tough problems such as energy spectrum and boundary condition are faced. To deal with those problems, the Monte Carlo global homogenization is adopted. The Reactor Monte Carlo code RMC is used to study the global homogenization method, and the one-step global homogenization method is proposed. The superimposed mesh geometry is also used to divide the physical models, leading to better geometric flexibility. A set of multigroup homogenization cross sections is online generated for each mesh under the real neutron energy spectrum and boundary condition, the cross sections are adjusted by the superhomogenization method, and no leakage correction is required. During the process of superhomogenization, the author-developed reactor core program NLSP3 is used for global calculation, so the global flux distribution and equivalent homogenization cross sections could be solved simultaneously. Meanwhile, the calculated homogenization cross section could accurately reconstruct the non-homogenization flux distribution and could also be used for fine calculation. This one-step global homogenization method was tested by a PWR assembly and a small reactor model, and the results show the validity.