Structural Analysis Research Articles

A staggered local damage model for fracture analysis in bi-material structures

This article is devoted to extension of the recently developed enhanced local damage model for failure prediction in bi-material structures. Compared to non-local models, the enhanced local model offers lower computational cost while the inherent mesh-dependency issue is treated. By defining equivalent strain based on the bi-energy norm concept and Mazars’s criterion, which considers both tensile and compressive strain components, the model aligns with the behavior of quasi-brittle materials. The state of material point is indicated by a damage parameter, ranging from 0 to 1, to represent the evolution from being fully intact to complete failure. An efficient staggered scheme is introduced, in which the equilibrium equation and the update of damage parameter are decoupled. The proposed model is validated with a series of three-point bending experimental tests on PMMA/Al6061 specimens reported by Lee and Krishnaswamy (2000). Good agreement is observed between the proposed model and experimental data, as well as numerical results from other authors, in crack path prediction.

Thermo-Mechanical Properties of Particulate Banana Epoxy Composite with Fruit Waste (Dragon Fruit Peel) Micro Filler for Household Applications

This study evaluates the thermo-mechanical characteristics of eco-friendly composite made of particulate banana fiber (reinforcement), epoxy resin (matrix) and dragon fruit peel powder (micro filler). The composites were developed using compression moulding technique with 3 factors, 4 variations and Taguchi orthogonal array design (L16). The proposed filler characterization results revealed that the density was 0.97 g/cm3 and combination of C–O, Ca–O, and Ca–Co could improve mechanical strength. Composites with 5 mm fiber length, 40 wt.% fiber weight, and 15 wt.% filler weight have a maximum tensile strength of 25.58 MPa, flexural strength of 44.47 MPa, impact strength 180.33 J/m, and hardness of 82.50 SD. The best composite’s thermal, wear, water and fatigue studies were proposed to suit household applications. The proposed filler improves fiber-resin bonding, which increases thermal stability to 245 °C, wear resistance, decreases water absorption, and results in a fatigue life count of 121000 cycles. Thus, this study concluded that the increasing filler content and decreasing particulate size had an impact on the thermo-mechanical characteristics of banana-reinforced polymeric composites. As a result, an eco-friendly polymeric composite mixer coupler model was developed. Comparative structural and model analyses were performed using ANSYS R17.2. The analysis results confirmed that the proposed composite had higher natural frequencies of 2766.5 Hz and lower deformation values of 0.089293 mm. This proves the proposed eco-friendly composite is a suitable replacement for a synthetic mixer coupler.

A Case Study of Problem-Based Learning from a Civil Engineering Structural Analysis Course

A Case Study of Problem-Based Learning from a Civil Engineering Structural Analysis Course

Structure of the human systemic RNAi defective transmembrane protein 1 (hSIDT1) reveals the conformational flexibility of its lipid binding domain.

In C. elegans , inter-cellular transport of the small non-coding RNA causing systemic RNA interference (RNAi) is mediated by the transmembrane protein SID1, encoded by the sid1 gene in the systemic RNA interference-defective ( sid ) loci. SID1 shares structural and sequence similarity with cholesterol uptake protein 1 (CHUP1) and is classified as a member of the cholesterol uptake family (ChUP). Although systemic RNAi is not an evolutionarily conserved process, the sid gene products are found across the animal kingdom, suggesting the existence of other novel gene regulatory mechanisms mediated by small non-coding RNAs. Human homologs of sid gene products - hSIDT1 and hSIDT2 - mediate contact-dependent lipophilic small non-coding dsRNA transport. Here, we report the structure of recombinant human SIDT1. We find that the extra- cytosolic domain (ECD) of hSIDT1 adopts a double jelly roll fold, and the transmembrane domain (TMD) exists as two modules - a flexible lipid binding domain (LBD) and a rigid TMD core. Our structural analyses provide insights into the inherent conformational dynamics within the lipid binding domain in cholesterol uptake (ChUP) family members.

Network structures of internet gaming disorder and gaming disorder: Symptom operationalization causes variation.

From 2022, the International Classification of Diseases, eleventh edition (ICD-11) includes the first mental disorder based on digital technology, "gaming disorder," which was previously suggested as a condition for further examination in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5). In this cross-sectional study, we provide the first large-scale network analysis of various symptom structures for these constructs to understand the complex interconnections between their proposed symptoms. Culturally diverse samples of 2,846 digital game players (M = 25.3 years) and 746 esports players (M = 23.5 years) were recruited. A network approach was applied to explore a multiverse of gaming disorder symptom structures, effects of item operationalization, and possible external moderators. Gaming disorder was measured using the Internet Gaming Disorder Scale 9-Short Form (IGDS9-SF), Gaming Disorder Test, and several items borrowed from Chinese Internet Gaming Disorder Scale, Personal Internet Gaming Disorder Evaluation-9, and Clinical Video game Addiction Test 2.0 scales. Two symptoms (loss of control and continued use despite problems) present in both, the DSM-5 and ICD-11, were systematically central to most of the analyzed networks. Alternative operationalizations of single items systematically caused significant network differences. Networks were invariant across groups of play style, age, gender, gaming time, and most of the psychosocial characteristics. Our results caution practitioners and researchers when studying and interpreting gaming disorder symptoms. The data indicate that even minor operational changes in symptoms can lead to significant network-level changes, thus highlighting the need for careful wording. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Partial Force Calculation and Structural Strength Analysis of Null-Flux Coil for Superconducting Electrodynamic Suspension Train

Partial Force Calculation and Structural Strength Analysis of Null-Flux Coil for Superconducting Electrodynamic Suspension Train

Structural Design and Mechanical Analysis of HTS CICC Made From Twisted Stack Slotted-Core Cable

Structural Design and Mechanical Analysis of HTS CICC Made From Twisted Stack Slotted-Core Cable

Sorption Efficacy of Weathered Basalt Rock for Metal Ions of Nuclear Importance

Background:: A safe and long-term isolation of radionuclides is crucial for efficient waste management in the nuclear fuel cycle. Clay minerals of geological origin are considered candidate barrier materials for the sequestration of nuclear waste for geological disposal applications. Objective:: The present study encompasses a systematic characterization of weathered basalt rock and the influence of its constituent clay minerals (formed mainly due to the weathering process) in the uptake of metal ions of nuclear importance, such as cesium (Cs+) and strontium (Sr2+). Methods: The structural profile of the weathered basalt has been investigated using different analytical techniques, including polarizing microscope, XRD, FTIR and EDXRF. The sorption behaviour of the rock sample for Cs+ and Sr2+ has been investigated in a comprehensive batch mode by varying the experimental conditions. The analytical findings for structure and batch sorption performance of the material have been further correlated to understand the influence of different parameters on the uptake of metal ions and the underlying mechanism. Results:: Structural analyses confirmed the presence of clay minerals viz., kaolinite, illite and montmorillonite in the sample. A comprehensive sorption performance assessment carried out in batch mode at different experimental conditions revealed that the uptake of both the metal ions was rapid and dependent on initial metal ion concentration and solution pH. The uptake of Cs+ ions was found to be higher as compared to the Sr2+ ions. EDXRF analysis confirmed the loading of Cs+ and Sr2+ on the weathered basalt. Experimental batch sorption data presented a better agreement with the theoretical Freundlich isotherm pertaining to the heterogeneous nature of the sorbent. Conclusion:: The studies highlight that the clay minerals formed by structural alteration of basalt rock upon intense weathering could be very useful in fixing the nuclear fission waste components such as Cs+ and Sr2+.

MagIC-Cryo-EM: Structural determination on magnetic beads for scarce macromolecules in heterogeneous samples.

Cryo-EM single-particle analyses typically require target macromolecule concentration at 0.05~5.0 mg/ml, which is often difficult to achieve. Here, we devise Magnetic Isolation and Concentration (MagIC)-cryo-EM, a technique enabling direct structural analysis of targets captured on magnetic beads, thereby reducing the targets' concentration requirement to < 0.0005 mg/ml. Adapting MagIC-cryo-EM to a Chromatin Immunoprecipitation protocol, we characterized structural variations of the linker histone H1.8-associated nucleosomes that were isolated from interphase and metaphase chromosomes in Xenopus egg extract. Combining Duplicated Selection To Exclude Rubbish particles (DuSTER), a particle curation method that removes low signal-to-noise ratio particles, we also resolved the 3D cryo-EM structures of H1.8-bound nucleoplasmin NPM2 isolated from interphase chromosomes and revealed distinct open and closed structural variants. Our study demonstrates the utility of MagIC-cryo-EM for structural analysis of scarce macromolecules in heterogeneous samples and provides structural insights into the cell cycle-regulation of H1.8 association to nucleosomes.

Characteristics Analysis of Different Photonic Crystal Fiber Lattice Structures

This study presents a comprehensive analysis of various photonic crystal fiber (PCF) lattice structures using the Finite Element Method (FEM). PCFs have gained significant importance in various optical and communication applications due to their unique optical properties. Understanding the characteristics and optimal designs of different PCF lattice structures is crucial for their effective utilization. In this research, we explore eight distinct lattice designs, including circle, square, pentagon, hexagon, heptagon, octagon, decagon, and dodecagon. We investigate how variations in the air-filling fraction (AFF), a critical structural parameter, affect the performance of these PCF structures. The utilization of FEM allows for a detailed analysis of these lattice structures, offering insights into their behavior under different conditions. By varying the AFF, we gain valuable insights into the optimal design choices for specific applications. This research aims to provide a deeper understanding of the applicability of each PCF lattice structure. By scrutinizing their performance and characteristics, it becomes possible to distinguish which lattice structure is best suited for various optical and communication applications. The findings from this study offer significant contributions to the field of photonics, guiding researchers and engineers in selecting the most suitable PCF lattice structure for their specific applications. Understanding the structural parameters that influence PCF behavior is a key step toward optimizing the performance of optical and communication systems.

Towards Faithful Model Explanation in NLP: A Survey

Abstract End-to-end neural Natural Language Processing (NLP) models are notoriously difficult to understand. This has given rise to numerous efforts towards model explainability in recent years. One desideratum of model explanation is faithfulness, that is an explanation should accurately represent the reasoning process behind the model’s prediction. In this survey, we review over 110 model explanation methods in NLP through the lens of faithfulness. We first discuss the definition and evaluation of faithfulness, as well as its significance for explainability. We then introduce recent advances in faithful explanation, grouping existing approaches into five categories: similarity-based methods, analysis of model-internal structures, backpropagation-based methods, counterfactual intervention, and self-explanatory models. For each category, we synthesize its representative studies, strengths, and weaknesses. Finally, we summarize their common virtues and remaining challenges, and reflect on future work directions towards faithful explainability in NLP.

Extraction Optimization, Structure Analysis and Antioxidant Activity of Polysaccharide from Sanghuangporus baumii

Introduction: In this study, we optimized the extraction process, analyzed the structure and assessed the antioxidant activity of Sanghuangporus baumii polysaccharide (SBP). The present results provide important information for the Sanghuangporus baumii polysaccharides in potential natural antioxidant effects. Background: The extraction and structural analysis of polysaccharides from Sanghuangporus has gained significant attention in the fields of chemistry, medicine, and life sciences. There is great significance in maximizing the extraction of polysaccharides from Sanghuangporus and developing their potential products in a scientific and rational manner. Objective: The study was designed to establish an efficient and practical extraction process for SBP, and then investigated the structure and the antioxidant activity. Methods: The Response Surface Methodology (RSM) based on Box-Behnken design was used to explore the ultrasound-assisted extraction of SBP, and the structure of SBP was studied by ultraviolet spectroscopy, infrared spectroscopy and other instrumental analysis methods. The total antioxidant capacity of SBP was studied by the Ferric Reducing Ability of Plasma (FRAP) method, and the scavenging capacity of ABTS+·, DPPH· and OH· was carried out as the index to investigate its antioxidant activity in vitro. Results: The statistical analysis results showed that the optimal conditions for extracting SBP were an ultrasound time of 20.74 min, ultrasound power of 268.40 W and material-liquid ratio of 1:25.71. Under optimal conditions, the experimental yield of SBP was 3.36 ± 0.01%. The RSM optimization process was applied to the experiment of complex enzyme extraction of SBP, and the yield increased to 4.72 ± 0.03%. Structural analysis showed that SBP mainly consisted of glucose, a small amount of mannose and galactose, and the molecular weight distribution was uneven, mainly concentrating in the three parts of 24.5,6.4,2.5 kDa. Moreover, SBP exhibited dose-dependent and strong reducing power and radical scavenging activity. For DPPH·, ABTS+· and OH· radical scavenging assays, IC50 values were 1.505 ± 0.050 mg/ml, 0.065 ± 0.036 mg/ml and 0.442 ± 0.007 mg/ml, respectively. Conclusion: In the present study, a β-linked heteroglucan (SBP) was extracted using the optimized process combining enzymes from the fruiting bodies of Sanghuangporus baumii. SBP exhibited effective and dose-dependent antioxidant activities. Our findings were of great value in terms of developing polysaccharides with potential natural antioxidants.

A review: plastic analysis in structures

Purpose Brief introduction on the importance and the need for plastic analysis methods were presented in the beginning section of this review. The plastic method for analysis was considered to be the more advanced method of analysis because of its ability to represent the true behaviour of the steel structures. Then in the following section, a literature analysis has been carried out on the previous investigations done on steel plates, steel beams and steel frames by other authors. The behaviour of them under different types of loading were presented and are under the investigation of innovative new analysis methods. Design/methodology/approach Structure member connections also have the potential for plastic failure. In this study, the authors have highlighted a few topics to be discussed. The three topics in this study are T-end plate connections to a square hollow section, semi-rigid connections and cold-formed steel storage racks with spine bracings using speed-lock connections. Connection is one of the important parts of a structure that ensures the integrity of the structure. Finally, in this technical paper, the authors introduce some topics related to seismic action. Application of the Theory of Plastic Mechanism Control in seismic design is studied in the beginning. At the end, its in-depth application for moment resisting frames-eccentrically braced frames dual systems is investigated. Findings When this study involves the design of a plastic structure, the design criteria must involve the ultimate load rather than the yield stress. As the steel behaves in the plastic range, it means the capacity of the steel has reached the ultimate load. Ultimate load design and load factor design are the methods in the range of plastic analysis. After the steel capacity has reached beyond the yield stress, it fulfills the requirement in this method. The plastic analysis method offers a consistent and logical approach to structural analysis. It provides an economical solution in terms of steel weight, as the sections designed using this method are smaller compared with elastic design methods. Originality/value The plastic method is the primary approach used in the analysis and design of statically indeterminate frame structures.

Linguistic analysis of fiction texts in the context of the frame theory

The aim of the study is to identify and analyse frame structures, activators, and concepts in texts to reveal their impact on the reader' s perception. The research employed the methods of semantic, structural, and intertextual frame analysis. Cronbach' s alpha was also used to verify the instruments used. The following cases were used in the work: Oxford English Corpus and International Corpus of English (ICE). It is noted that frame activators such as "great heat", "hell heat", "hot wind", and "scorching sun" evoke associations with scorching heat and unusual warmth in the desert. These frames convey the impression of life danger, exhaustion, and severity of conditions. In turn, phraseological units such as "fresh waters", "bloody sunset", and "dried earth" reveal the contradictory nature of the image of the desert, where even such natural phenomena as water and sunset acquire a new, deep shade of meaning. The application of this theory was found to reveal complex language structures and their influence on the understanding and perception of texts. The obtained results open up new opportunities for educational and literary analysis, deepening the understanding of language mechanisms in fiction. Further studies in the field of linguistic analysis of texts should be aimed at considering the interaction between different works of art, focusing on the frame perspective. It is also worth paying attention to the possibilities of using the theory of frames to fulfill practical assignments, such as automatic text analysis.

The mediating impact of assessment process in the relationship between project-based learning and teamwork skills’ development

The significance of teamwork skills has been acknowledged in most professions and many organizations make performance evaluation judgments based on learners’ teamwork skills. Project-based learning (PBL) has the ability to harness the ability of students to work together. Consequently, this study evaluated the PBL based on the workshop/laboratory experiences of students by measuring the mediating effect of the assessment process to which PBL is employed to enhance students’ teamwork skills. A set of structured questionnaires was purposively administered to 205 students in technology and vocational education-related courses in tertiary institutions of South-Western States in Nigeria. The key analytical methods for the reliabilities test, normality measurements, composite average, explorative factor analysis, confirmative factor analysis, calculation, and structural model analyzes were Structural Equation Modeling (SEM), using version Statistics Package for Social Sciences (SPSS) Version 22.0 and 22.0 of Movement Structures Analysis (AMOS). The outcomes of the analysis revealed that PBL in relation to teamwork skills were statistically insignificant. Though, the assessment process on learners’ teamwork skills was found to be significant. Thus, it implies there is a need to reinforce learners’ assessment process in influencing PBL towards the development of students’ teamwork skills in their various institutions.

Synthesis, Antimicrobial Activities, and Molecular Modeling Studies of Agents for the Sortase A Enzyme.

Sortase A (SrtA) is an attractive target for developing new anti-infective drugs that aim to interfere with essential virulence mechanisms, such as adhesion to host cells and biofilm formation. Herein, twenty hydroxy, nitro, bromo, fluoro, and methoxy substituted chalcone compounds were synthesized, antimicrobial activities and molecular modeling strategies against the SrtA enzyme were investigated. The most active compounds were found to be T2, T4, and T19 against Streptococcus mutans (S. mutans) with MIC values of 1.93, 3.8, 3.94 μg/mL, and docking scores of -6.46, -6.63, -6.73 kcal/mol, respectively. Also, these three active compounds showed better activity than the chlorohexidine (CHX) (MIC value: 4.88 μg/mL, docking score: -6.29 kcal/mol) in both in vitro and in silico. Structural stability and binding free energy analysis of S.mutans SrtA with active compounds were measured by molecular dynamic (MD) simulations throughout 100 nanoseconds (ns) time. It was observed that the stability of the critical interactions between these compounds and the target enzyme was preserved. To prove further, in vivo biological evaluation studies could be conducted for the most promising precursor compounds T2, T4, and T19, and it might open new avenues to the discovery of more potent SrtA inhibitors.

Catalytic Ring Expanding Difluorination: An Enantioselective Platform to Access β,β-Difluorinated Carbocycles.

Cyclic β,β-difluoro-carbonyl compounds have a venerable history as drug discovery leads, but limitations in the synthesis arsenal continue to impede chemical space exploration. This challenge is particularly acute in the arena of fluorinated medium rings where installing the difluoromethylene unit subtly alters the ring conformation by expanding the internal angle (∠C-CF2-C>∠C-CH2-C): this provides a handle to modulate physicochemistry (e.g. pKa). To reconcile this disparity, a highly modular ring expansion has been devised that leverages simple α,β-unsaturated esters and amides, and processes them to one-carbon homologated rings with concomitant geminal difluorination (6 to 10 membered rings, up to 95 % yield). This process is a rare example of the formal difluorination of an internal alkene and is enabled by sequential I(III)-enabled O-activation. Validation of enantioselective catalysis in the generation of unprecedented medium ring scaffolds is reported (up to 93 : 7 e.r.) together with X-ray structural analyses and product derivatization.

Efficient Synthesis and Structural Analysis of Chiral 4,4'-Biazulene.

4,4'-Biazulene is a potentially attractive key component of an axially chiral biaryl compound, however, its structure and properties have not been clarified owing to the lack of its efficient synthesis. We report a breakthrough in the reliable synthesis of 4,4'-biazulene, which is achieved by the access to azulen-4-ylboronic acid pinacol ester and 4-iodoazulene as novel key synthetic intermediates for the Suzuki-Miyaura cross-coupling reaction. The X-ray crystallographic analysis of 4,4'-biazulene confirmed its axial chirality. The enantiomers of 4,4'-biazulene were successfully resolved by HPLC on the chiral stationary phase column. The kinetic experiments and DFT calculations indicate that the racemization energy barrier of 4,4'-biazulene is comparable to that of 1,1'-binaphthyl.

Application of deep learning methods for automated analysis of retinal structures in ophthalmology

This article examines a current area of research in the field of ophthalmology the use of deep learning methods for automated analysis of retinal structures. This work explores the use of deep learning methods such as EfficientNet and DenseNet for the automated analysis of retinal structures in ophthalmology. EfficientNet, originally proposed to balance between accuracy and computational efficiency, and DenseNet, based on dense connections between layers, are considered as tools for identifying and classifying retina features. Automated analysis includes identifying pathologies, assessing the degree of their development and, possibly, diagnosing various eye diseases. Experiments are performed on a dataset containing a variety of images of retinal structures. Results are evaluated using metrics of accuracy, sensitivity, and specificity. It is expected that the proposed deep learning methods can significantly improve the automated analysis of retinal images, which is important for the diagnosis and monitoring of eye diseases. As a result, the article highlights the significance and promise of using deep learning methods in ophthalmology for automated analysis of retinal structures. These methods help improve the early diagnosis, treatment and monitoring of eye diseases, which can ultimately lead to improved healthcare quality and improved patient lives.

Design Aspects of Lower Limb Exoskeleton

Aim: This research work aimed at the design, simulation, and validation of a lower limb exoskeleton for rehabilitation. The device can provide regressive gait training for patients suffering from lower limb mobility disorders. Background: People suffering from mobility disorders, such as spinal cord injuries, and other related diseases are in high proportion. Exoskeletons play a vital role in enhancing the lifestyle of people with disorders. Devices that provide locomotion assistance and help in reducing the burden of therapists through effective and repetitive gait training are in high demand. Exoskeletons have further extended to the fields of the military to enhance the performance of physically abled persons. Prototype development of lower limb exoskeletons is too expensive and many of them are patented. The requirement for this system to perform human trials is subjective to several medical and ethical norms. Thus, there exists a need to evaluate and validate the exoskeleton designs. Methods: In this work, the design has been made inclusive of different body shapes and sizes. The device has been modeled in SOLIDWORKS and its structural integrity has been analyzed using the ANSYS software. Later, the model has been subjected to environmental assessment and then motion analysis using the ADAMS software. Results: The structural integrity analysis has revealed the design to be adequate to carry the applied load as the stresses induced were less than the yield strength of the material. The sustainability analysis showed that LLE made of aluminium alloy had less impact on the environment relative to the other two materials. Conclusion: The kinematic simulation revealed that the angular amplitudes, the reaction force of the right hip and knee joint, and the contact force between the shoe and the ground of the exoskeleton agreed well with the experimental findings of the literature.