Second-order Structures Research Articles

Low Roundoff Noise of Two Sparse Second-Order Balanced Realization-Based Structures

Low Roundoff Noise of Two Sparse Second-Order Balanced Realization-Based Structures

The Comparison of Several Factorial Structures of the Cornell Critical Thinking Test Level Z

"The Cornell Critical Thinking Test (CCTT) level Z is a broadly applied instrument for the measurement of undergraduate, gifted students’ and adults’ critical thinking abilities, however, there is a lack of studies in the literature investigating its factorial structure. The test developers emphasize the interpretation of the test results as a general critical thinking factor, including different cognitive abilities, but also highlight the overlap between the items of the subfactors. The aim of the study is the investigation of internal consistency, the comparison of different factorial structures (unidimensional, correlated, and hierarchical models), and gender invariance testing of the CCTT level Z. Hungarian-speaking undergraduate students participated in the study (N = 825). For the confirmatory factor analysis (CFA) the Mplus version 8.7, with weighted least squares mean and variance adjusted estimation was used. Measurement invariance of the test across genders was analyzed using Muthén’s two-step procedure for dichotomous data. The results indicated that the correlated four-factor and second-order structures of the test exceeded the acceptable model fit criteria. Post hoc inspection was conducted on the second-order four-factor model, indicating a shortened 22-item version of the test (with a general critical thinking factor, including four subfactors: deduction, meaning and fallacies, induction, assumption identification) with excellent fit indices [χ2 (203) = 259.309, CFI = .967, TLI = .963, RMSEA = .018, SRMR = .056]. Configural and scalar invariance of the abbreviated Hungarian version of the test across genders were confirmed. Keywords: critical thinking, undergraduate students, confirmatory factor analysis, measurement invariance"

Lightweight self-similar hierarchical metamaterials with subwavelength and superwide bandgaps

Vibration isolation has always been a flourishing subject with practical interest because it helps in reducing structure vibration that has serious effects on moving vehicles and equipment operation, and it exists everywhere and incessantly in daily life. With the advantage of predictable and designable frequency bandgaps, elastic metamaterial has attracted a lot of research attention in the past decade and beyond. Inspired by the design of Chinese traditional window and kirigami pattern, this paper introduces a self-similar hierarchical elastic metamaterial that can offer superwide subwavelength bandgaps without increasing system weight. The comparison of band structures obtained by finite element simulation manifests significant effects of hierarchy design on lowering bandgap frequency and widening bandgap width. Through comprehensive analyses, the principles for maximizing bandgap width without increasing system weight are highlighted. The vibration response of supercells that consist of 2 × 3 unitcells is constructed for both the first- and second-order hierarchical structures are investigated. After analyzing the different working frequencies of supercells with distinct hierarchical ratios, the first-order and second-order hybrid hierarchical supercells containing unitcells with complementary bandgaps are designed. An excellent increase in effective and perfect attenuation width is demonstrated. The work presented herein provides a new and effective method for generating subwavelength and superwide bandgaps in lightweight structures. This advancement holds great promise for improving the application potential of elastic metamaterials.

Tucker tensor decomposition with rank estimation for sparse hyperspectral unmixing

ABSTRACT Hyperspectral image unmixing gives increasing focus on the structural integrity of the spatial-spectral information. A large number of methods exploit the sparse and low-rank properties of the abundance vectors, abundance matrices and abundance maps, which are first-order or second-order structures, and are hard to preserve the integrated structure of the abundance. The abundance tensor formed by overlapping the abundance maps of endmembers sequentially is a more appropriate expression of the abundance. However, hyperspectral unmixing studies based on the abundance tensor are still in the minority, and most of these methods either inherently degrade the tensor structure to some extent, which is hard to distinguish the low-rankness of different dimensions; or are based on tensor decomposition methods, which always require a pre-estimation of the tensor rank, thus the unmixing accuracy depends on the rank estimation. In this article, we propose an unmixing model on tensor framework, in which the abundance tensor is approximated by a truncated Tucker tensor decomposition (TTD). Since the generated factor matrices are relatively low-rank, the low-rankness exploration of the abundance tensor is achieved potentially by this way. Moreover, we further improve the unmixing performance by a suitable rank estimation. The more flexible algorithm Tucker tensor decomposition with rank estimation for sparse hyperspectral unmixing (TTDRE) is proposed to differentiate the low-rankness of different dimensions of the abundance tensor while preserving the structural integrity. Experiments on synthetic and real data illustrate the effectiveness of our method.

A multifunctional metastructure with energy dissipation and low-frequency sound-absorption optimized for decoupling by genetic algorithm

A multifunctional metastructure has been proposed with the aim of having both energy-absorbing and sound-absorbing capabilities through the use of a rubber-filled re-entrant honeycomb frame. The acoustic and mechanical properties of the metastructure are decoupled utilizing a genetic algorithm so that the properties can be designed separately. The re-entrant honeycomb frame has the role of energy absorption, while the rubber filling allows the structure to form a Helmholtz-type absorbing material. The form of deformation of the structure under quasi-static compression is investigated by means of experiments and simulations, which are used to determine the variation of the cavity volume with compression. With the optimization by genetic algorithm, the first-order and second-order acoustic structures with excellent acoustic performance before and after compression have been obtained. At the same time, a continuous broadband sound- and energy-absorbing metastructure has been produced by combining these two structures. This work provides a remarkably new strategy for the integrated design of sound- and energy-absorbing structures and has a significant prospect for engineering applications such as aerospace engineering.

Energy Absorption Characteristic of Biomimetic Gradient Hierarchical Multicellular Tubes Under Axial Impact

This paper introduces a biomimetic gradient hierarchical multicellular structure consisting of two tree-like fractal variants: one based on vertex connections (HCV) and the other based on wall connections (HCW). We investigate their mechanical behavior and deformation through numerical simulations. Our findings reveal that, irrespective of whether they have the same wall thickness or mass, second-order and third-order structures exhibit superior energy absorption capacity (EA) and crushing force efficiency (CFE) compared to first-order structures, resulting in significantly enhanced crashworthiness performance. In the case of HCV structures with identical wall thickness, the third-order structure outperforms the first-order structure by 79.73% in specific energy absorption (SEA) and by 38.51% in CFE. Similarly, for HCW structures, the third-order variant surpasses the first-order one by 45.57% in SEA and 28.39% in CFE. We also conduct a parametric study, exploring the influence of inner circle diameter, fractal coefficient, and fractal angle on the crashworthiness of biomimetic gradient hierarchical multicellular structures. We identify the optimal fractal coefficient and inner diameter distribution range for HCV when the fractal angle is 60°. Lastly, we compare these structures with traditional multicellular tubes, demonstrating that biomimetic gradient hierarchical multicellular tubes achieve up to 50.34% higher SEA and 55.13% higher CFE. The results of this study offer valuable design insights for developing lightweight and efficient energy-absorbing structures.

Patterns in Temporal Networks with Higher-Order Egocentric Structures.

The analysis of complex and time-evolving interactions, such as those within social dynamics, represents a current challenge in the science of complex systems. Temporal networks stand as a suitable tool for schematizing such systems, encoding all the interactions appearing between pairs of individuals in discrete time. Over the years, network science has developed many measures to analyze and compare temporal networks. Some of them imply a decomposition of the network into small pieces of interactions; i.e., only involving a few nodes for a short time range. Along this line, a possible way to decompose a network is to assume an egocentric perspective; i.e., to consider for each node the time evolution of its neighborhood. This was proposed by Longa et al. by defining the "egocentric temporal neighborhood", which has proven to be a useful tool for characterizing temporal networks relative to social interactions. However, this definition neglects group interactions (quite common in social domains), as they are always decomposed into pairwise connections. A more general framework that also allows considering larger interactions is represented by higher-order networks. Here, we generalize the description of social interactions to hypergraphs. Consequently, we generalize their decomposition into "hyper egocentric temporal neighborhoods". This enables the analysis of social interactions, facilitating comparisons between different datasets or nodes within a dataset, while considering the intrinsic complexity presented by higher-order interactions. Even if we limit the order of interactions to the second order (triplets of nodes), our results reveal the importance of a higher-order representation.In fact, our analyses show that second-order structures are responsible for the majority of the variability at all scales: between datasets, amongst nodes, and over time.

Optically Transparent Dual-Band Metamaterial Absorber Using Ag Nanowire Screen-Printed Second-Order Cross-Fractal Structures

In this paper, we propose an optically transparent dual-band metamaterial absorber (MMA) that uses Ag nanowire screen-printed fractal structures. The proposed MMA exhibits near-perfect absorption in the C- and K-bands. This dual-band absorption property is achieved through two inductive–capacitive (L-C) resonances located at 6.45 and 21.14 GHz, which are generated by the second-order fractal structures. We analyzed the microwave absorbing mechanisms through the distributions of the surface current and electromagnetic field on the top and bottom layers. The MMA demonstrates an optical transmittance of 63.1% at a wavelength of 550 nm. This high optical transmittance is attained by screen printing transparent Ag nanowire ink onto a transparent PET substrate. Since screen printing is a simple and low-cost fabrication method, the proposed MMA offers the advantages of being low cost while having the properties of optical transparency and effective dual-band absorption. Consequently, it holds great potential for the radar stealth application of C- and K-bands in that it can be attached to the windows of stealth aircraft due to its optical transparency and dual-band near-perfect absorption property.

Parental mental health and reporting of their child's behaviour: measurement invariance of the French version of the parental strengths and difficulties questionnaire.

Symptomatic effects of mental disorders in parents could bias their reporting on their child's mental health. This study aimed to investigate the measurement invariance of the French version of the parental Strengths and Difficulties Questionnaire (SDQ) across parental mental health in a sample (N = 20,765) of parents of children aged 3 to 17years in France. Confirmatory factor analysis (CFA) and Exploratory Structural Equation Modelling (ESEM) were used to evaluate the fit of three known alternative SDQ factor structures (five, three, or second-order factor structures). Invariance was tested across parental mental health (present anxiety and depressive symptoms, psychiatric history) and across socio-demographic characteristics (child's age, child's gender, parent's gender, parent's educational level). CFA models showed a poor fit, while all ESEM models achieved acceptable or good fit, with the five-factor model presenting the best fit. Invariance was observed for all characteristics tested, indicating that the SDQ can be used to study the links between parental mental health and their child's mental health without bias. However, ESEM showed that the hyperactivity/inattention and conduct problems dimensions were not well differentiated in the French version of the SDQ.

Deformation and paleopiezometry of auriferous quartz veins in Archean orogenic gold deposits of the Abitibi greenstone belt

Most Archean orogenic gold deposits are associated with major faults such as the Larder Lake-Cadillac fault zone (LLCFZ) in the Superior craton and are hosted in or adjacent to second-order structures as quartz vein systems. Microstructures induced by quartz deformation in these faults or shear zones, such as typical textures of recovery and dynamic recrystallization, give indication of the P-T conditions during deformation. Electron backscatter diffraction (EBSD) analysis of grain lattice orientation and grain size determination, for flow stress calculation, are commonly performed on mylonite or quartzite samples from shear zones. This study tests the validity of such methods on hydrothermal auriferous quartz veins to better constrain the conditions of quartz vein deformation in the vicinity of the LLCFZ and evaluate the effect of depth and local variations on the microstructures and flow stress. Samples were collected in 24 gold deposits and showings along the LLCFZ. The microstructural observations and EBSD analysis allowed the distinction of six microstructural types within the studied samples. Samples analyzed with EBSD display a log-normal distribution of recrystallized grain sizes that is consistent with data for natural samples. The calculated flow stress is highly variable between samples and ranges from 38.2 + 5.1/-6.1 to 74.5 + 2.2/-3.0 MPa in surface samples only. Quartz recrystallization overprints primary textures in all but one samples, which indicates that recrystallization and its associated deformation occurred after the complete crystallization of the veins. Samples with bimodal distribution of recrystallized quartz grain sizes highlight the potential of quartz veins to record several deformation events. Samples are recrystallized at higher temperature and lower stress in the east than in the west of the LLCFZ, which could indicate the exposure of a deeper crust in the east. These data underline the potential of quartz vein microstructures to contribute to the evaluation and evolution of deformation conditions of auriferous quartz vein in an orogenic context.

High-Level Hessian-Based Image Processing with the Frangi Neuron

The Frangi neuron proposed in this work is a complex element that allows high-level Hessian-based image processing. Its adaptive parameters (weights) can be trained using a minimum number of training data. In our experiment, we showed that just one image is enough to optimize the values of the weights. An intuitive application of the Frangi neuron is to use it in image segmentation process. In order to test the performance of the Frangi neuron, we used diverse medical datasets on which second-order structures are visualized. The Frangi network presented in this paper trained on a single image proved to be significantly more effective than the U-net trained on the same dataset. For the datasets tested, the network performed better as measured by area under the curve receiver operating characteristic (ROC AUC) than U-net and the Frangi algorithm. However, the Frangi network performed several times faster than the non-GPU implementation of Frangi. There is nothing to prevent the Frangi neuron from being used as part of any other network as a component to process two-dimensional images, for example, to detect certain second-order features in them.

Psychometric properties of the Spanish Acceptance and Action Questionnaire for Weight-Related Difficulties-Revised (AAQW-R).

Based on the original 22-item single-factor questionnaire, the 10-item second-order Acceptance and Action Questionnaire for Weight-Related Difficulties-Revised (AAQW-R) was developed for measuring weight-related experiential avoidance. This instrument showed good psychometric properties, and it has been validated to different contexts. However, no Spanish validation has been conducted, to date. Therefore, the aim of this study was to analyze the psychometric properties of the Spanish version of the instrument in a sample of adults from the Spanish context across the whole body mass index spectrum (N = 393). Confirmatory factor analysis was performed to examine the fit of the first- and second-order AAQW-R structures. Internal reliability, construct validity, external reliability, and sensitivity to change were also analyzed. The Spanish AAQW-R presented a good fit to the data, the overall scale and subscale scores showed acceptable-to-good internal consistencies, and adequate construct validity. Likewise, test-retest reliability parameters were high, and the instrument showed sensitivity to change. The findings demonstrate that the Spanish AAQW-R is an instrument with good psychometric properties, supporting its use for measuring adults' weight-related experiential avoidance in both research and clinical settings within the Spanish context. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Energy absorption characteristics of novel bio-inspired hierarchical anti-tetrachiral structures

Most natural (or biological) materials possess chiral and hierarchical properties, thus can exhibit outstanding mechanical properties, such as shear resistance, vibration attenuation, and impact resistance. Inspired by these natural materials, an innovative category of hierarchical chiral structure is proposed in an attempt to enhance their energy absorption capacity. Based on the chiral element composed of the central ring and connected ligaments, the hierarchical chiral structure is constructed by recursively replacing the central ring with a group of smaller rings connected through ligaments. The energy absorption properties of the present hierarchical structure are numerically analyzed with various hierarchies and impact velocities in terms of the deformation and plastic failure. It is found that hierarchical anti-tetrachiral structures exhibit unique “necking” deformation mode at a low speed impact. In addition, the second-order anti-tetrachiral structures can not only improve the specific mass energy absorption and the specific volume energy absorption but also effectively depress the peak stress compared to the first-order anti-tetrachiral structures. The results provide a new insight into the impact performance of hierarchical chiral and anti-chiral structures, which may contribute to the excellent design of auxetic components for crashworthiness applications.

Synthesis of soft-core hard-shell nanoparticles by visible PET-RAFT polymerization in dispersion conditions

Photoinduced electron/energy transfer (PET)-RAFT polymerization is an innovative technique for the synthesis of new nanomaterials moving towards greener conditions and process optimization. In the current work, we present a fast, simple, and robust methodology for the synthesis of spherical soft-core hard-shell nanoparticles in a fashionable controlled way. We exploited ZnTPP for the synthesis of poly(dimethyl acrylamide)-b-poly(butyl acrylate) (PDMA-b-PBA) block copolymer in various alcoholic media in dispersion conditions. The use of a homemade photoreactor allows to carry out several reactions simultaneously and to obtain quickly the optimization of the experimental conditions. In all cases, NMR analysis highlights the success of the PDMA-b-PBA polymerizations with very good yield (α > 75%) and low dispersity (Đ < 1.3). Dynamic light scattering (DLS) and TEM microscopy were used to analyze the NPs morphology, which varies from spherical-like shape to more complex second-order structures, depending on the water content of the alcoholic media. In order to improve the particles synthesis, making the process easier to scale up and reducing the use of organic solvents, one-pot polymerization was implemented with promising results. Finally, we demonstrate that a significant amount of photocatalyst is retained in the soft core, feature that can open the door for the production of innovative materials for photophysic applications.

Crushing behavior and energy absorption of the thousands-of-eyes-Bodhi-inspired novel hierarchical cellular structure

Natural hierarchical materials are proved to have excellent mechanical properties and have been widely applied in the design concept of engineering materials. In this study, inspired by the hierarchical structure of the thousands-of-eyes-Bodhi (TEB), a novel biomimetic hierarchical cellular structure is designed and fabricated using 3D printing technology. The crushing resistance capability and deformation mode of TEB-inspired hierarchical cellular structure are investigated by experiments and simulation methods. Meanwhile the deformation processes are recorded by the compression experiments, and the strain field distributions are analyzed by the digital image correlation (DIC) method. Comparing the mechanical behaviors of square tube, second-order and TEB-inspired hierarchical cellular structures, it is found that the structure hierarchy affects the deformation mode, improves the strain field distribution, delays the strain concentration, and enhances the crashworthiness. It is also noted that the TEB-inspired hierarchical cellular structure exhibits different deformation modes and strain field distributions in the transverse and longitudinal directions, and shows better crushing resistance in the longitudinal direction. In addition, compared with other typical natural materials and engineering materials, the TEB-inspired hierarchical cellular structure possesses superior specific energy absorption and specific strength. These findings provide a new perspective for the application of biomimetic engineering materials.

Vector peregrine composites on the periodic background in spin–orbit coupled Spin-1 Bose–Einstein condensates

Vector Gross–Pitaevskii system in spin–orbit coupled Spin-1 Bose–Einstein condensates is simplified into Manakov system. By means of the nonrecursive Darboux method, vector Peregrine solutions were given, including first-order and second-order vector Peregrine solutions with four structural parameters. From these solutions, vector peregrine composites on the periodic background are found by modulating the magnitudes of four structural parameters, including first-order and second-order Peregrine structures on the periodic background, and Peregrine doublets and Peregrine “three sisters” on the periodic background. The influence of the wave number and amplitude parameters on the first-order and second-order Peregrine structures on the periodic background for three components is studied. These results will provide a deeper understanding of nonlinear wave phenomena in spin–orbit coupled Spin-1 Bose–Einstein condensates.

Development of Summative Assessment Instruments for the Affective Aspects of Learning History

Instruments for measuring both the affective and psychomotor aspects of teaching are required. The study's overarching goal is to create a reliable and valid assessment tool for measuring affective competency (values contained in history). Nine hundred thirty-five students from Medan's XI Social Sciences high school participated as research subjects. An affective aspect assessment sheet, which is a questionnaire with various statements to gauge affective aspects, was used to collect research data. To compare measurement models and make it simpler to analyze model correctness, structural equation modelling (SEM) analysis with first- and second-order components was employed in the data analysis. The findings of the first-order confirmatory factor analysis using the ML (maximum likelihood) technique indicated that all items had a correlation coefficient greater than 0.32, and the results of testing using the model had a significance level of 0.0001, according to the research analysis. The structural equation model (SEM) findings, with support from second-order structures, are also estimated with adequate theoretical confidence. The construct reliability (CR) and variance extract (VE) coefficients indicate that the designed instrument complied with the reliability coefficient acceptability limits of 0.70 for CR and 0.50 for VE. The development process resulted in an affective competency assessment tool with 84 valid and reliable items spread across 5 dimensions and 14 indicators. The instruments created were therefore shown to be valid and reliable for assessing affective aspects of learning history. The findings of this study are utilized to diagnose student potential, particularly concerning affective components, so that students are aware of their strengths and weaknesses. The findings of this study are utilized by stakeholders as input for policymaking, particularly in the area of education.

A Preliminary Psychometric Investigation of a Chinese Version of Athlete Engagement Questionnaire (AEQ)

Athlete engagement is one of the key indicators of athletes' positive psychology. It plays a crucial role in coping with burnout and disengagement, creating a flow experience, and improving their competitive ability and performance. In the last two decades, a mountain of literature has focused on engagement in different research settings. In the world of sports, the Athlete Engagement Questionnaire (AEQ) has been proven to be a reliable instrument to access athletes' engagement at both amateur and elite levels. The aim of this study is to investigate the psychometric properties of the Chinese version of AEQ. The original English athlete engagement questionnaire was translated into Chinese using the method of back-translation for data collection. Subsequently, 379 samples were performed for data analysis, mainly focusing on confirmatory factor analysis to examine the four-factor and second-order factor structures of 16 items measuring athlete engagement. The results reproduced four components of AEQ, which included a total of 16 items. The instrument demonstrated acceptable composite reliability (.887 to .905) and convergent validity (> 0.5), except that the discriminant validity was slightly insufficient. The results showed that the Chinese version of AEQ as a second-order factor structure is better than the four-factor structure, that is, athlete engagement as an overarching construct composed of four factors: confidence, dedication, enthusiasm, and vigor. The findings offer a useful and reliable instrument for athlete engagement, which helps researchers better capture the experience and engagement of athletes in the Chinese sports context.

Wake flow field of a wall-mounted pipe with spoiler on a rough channel bed

This research work focuses on the wake flow region of a cylinder with a spoiler on a rough bed under steady flow conditions. The acoustic Doppler velocimetry was used for the measurement of three-dimensional velocity data for two Reynolds numbers in a fully developed turbulent flow around the cylinder with a spoiler. The mean flow velocities, second-order turbulence structures, and conditional statistics were investigated in the wake region of the spoilered cylinder. The flow was separated from the spoiler with the formation of two shear layers between free surface flow and recirculating flow. It is observed that the flow is reattaching to the bed at 11D irrespective of the Reynolds number. Downstream of the cylinder, the mean velocity distributions are asymmetric due to the wall–wake effect, and the point of inflection is observed for each velocity profile at z = 0.40ẟ. The turbulence intensities, Reynolds stresses, and TKE are highly enhanced in the wake region of the cylinder as compared to their respective upstream values for both runs. The turbulence intensities, Reynolds normal stresses, Reynolds shear stresses, and turbulent kinetic energy are attaining peaks at z = 0.4 ẟ for all the streamwise locations, and the peaks are found to be highest at x = 10D. The quadrant analysis results indicate that the sweeps are dominating bursting events in the inner and intermediate layers, while ejections are dominating in the outer layer of the wake region. As the hole size, H increases ejections stress fraction rises as compared to that of the sweeps in the wake region for z = 0.2–0.7 h.

Вулканические комплексы и тектоно-магматические этапы эволюции гайотов Магеллановых гор (Тихий океан). Сообщение 2: Тектоно-магматические этапы

Five tectonic-magmatic stages are distinguished in the evolution of the guyots of the Magellan Seamounts: 1 — Late Jurassic-Early Cretaceous (earliest Cretaceous — ~160–140 (?) Ma); 2 — Early Cretaceous (Late Barremian(?)-Aptian-Albian — ~127–96 Ma); 3 — Late Cretaceous (Late Cenomanian (?)-Turonian-Early Campanian — ~95–76 Ma); 4 — Late Cretaceous (Late Campanian-Maastrichtian — ~74.5–66.0 Ma); 5 — Cenozoic — 66–0 Ma. Each of the tectonic-magmatic stages corresponds to a certain age complex of volcanic rocks of the Magellan Seamount. Tectonic-magmatic stages have different durations and played different roles in the evolution and formation of the modern structure of the guyots of the Magellanic Seamounts. Each of the tectono-magmatic stages characterizes a specific geomorphological space of guyots (base, main part of the edifice, small complicating superimposed structures of the 2-nd order). Each of the tectonic-magmatic stages characterizes a specific geomorphological space of guyots (base, main body, small complicating superimposed second-order structures). On the whole, the tectonic-magmatic stages of the evolution of the Magellan Seamounts are in good agreement with the evolution stages of some other regions of the Pacific Ocean and correspond to the previously established periods of their tectonic-magmatic activation.