Local Strength Research Articles

First-principles calculations of orthorhombic chalcogenide ABX3 (A = Ca, Sr, Ba; B = Ge, Sn; X = O, S, Se, Te) perovskites by cation and anion variation

The first-principles calculations are used to investigate on the structural, electronic, optical properties of orthorhombic chalcogenide ABX3 (A = Ca, Sr, Ba; B = Ge, Sn; X = O, S, Se, Te) perovskites. All cation and anion variations will only change the lattice parameters, but the orthorhombic crystal structures maintain stability apart from CaGeS3. The electron density difference demonstrates the differences in interaction strength and degree of electron localization to some extent in various systems. The sulfide perovskites are all semiconductors with bandgaps between 1 - 3 eV while the variable anions can realize the transition from the insulator (5.263 eV) to narrow semiconductors (0.134 eV). Besides, the photoresponse can be modulated to a better match with solar irradiance by anion variation. Among all studied SrSnX3 (X = O, S, Se and Te) materials, SrSnSe3 has the best performance as a solar absorber due to its best light absorption and proper bandgap value (∼1.6 eV).

Effect of existing holes under the loading plate on local compressive strength of plain concrete blocks: an experimental and numerical study

Effect of existing holes under the loading plate on local compressive strength of plain concrete blocks: an experimental and numerical study

Correlations between local chemical fluctuations and grain boundary strength in Ti-Zr-Nb-Ta-Mo refractory multi-principal element alloys

Ti-Zr-Nb-Ta-Mo refractory multi-principal element alloys typically exhibit high yield strength while tensile ductility tends to be poor. In this study, we found that even after solid solution treatment of Ti-Zr-Nb-Ta-Mo alloys, significant change in ductility occur due to the local chemical fluctuations. Ta's dramatic chemical fluctuations cause variations in atomic-scale strain fields, leading to reduced grain boundary strength and brittle fracture. First-principles calculations show that (Ti, Zr)-rich at the grain boundaries increases the delocalization of valence electrons, leading to longer bond lengths and reduced crystal orbital bond index values, thereby causing grain boundary embrittlement. Our findings explore the root causes of brittleness in Ti-Zr-Nb-Ta-Mo alloys at the atomic and electronic scales, providing not only a method to analyze grain boundary embrittlement using bond length, electronic localization function and crystal orbital bond index, but also a theoretical guidance for improving the mechanical properties via grain boundary structure optimization.

POLARIZATION OF LOCAL COMMUNITY ORIENTATION TO THE DEVELOPMENT OF ECO-RURAL TOURISM IN KERINCI REGION, JAMBI PROVINCE, INDONESIA

Rural areas are increasingly the focus of exploration by various stakeholders. However, local communities, as landowners in these regions, often do not reap the full benefits. This issue stems from their limited involvement in regional development and a lack of awareness about ongoing projects. Local communities play a crucial role in the success of rural development, and understanding their attitudes is vital.This study aimed to explore local community attitudes toward eco-rural tourism development in Kerinci Regency, Jambi Province. A closed-ended questionnaire, designed with a "One Score One Indicator" system, assessed various factors including socio-cultural aspects, conservation, ethnic politics, economics, regional development, tourism, and landscape ecology across six villages. The analysis of local community orientation was conducted using quantitative descriptive methods and One-Way ANOVA statistical tests.Results indicated a positive polarization in community attitudes across all villages, showing strong support for eco-rural tourism. By focusing on the identified indicators, local communities are motivated to collaborate and enhance their rural areas through eco-tourism initiatives. The findings suggest that these communities possess significant potential to develop their regions in line with eco-rural tourism principles. Additionally, the insights gained can inform the creation of eco-rural tourism programs that emphasize community involvement and leverage local strengths. This approach aims to ensure that rural communities benefit from the exploration and development occurring in their areas.

Climate Risk Management among Smallholder Farmers: A Comparative Analysis of Flood-prone Alappuzha and Drought-affected Gondia in India

Climate change poses significant risks to agricultural systems worldwide, particularly in developing countries where smallholder farmers have limited adaptive capacity. This study examines the socioeconomic and demographic factors influencing climate risk management practices among smallholder farmers in two contrasting regions of India: the flood-prone Alappuzha district in Kerala and the drought-affected Gondia district in Maharashtra. Using data collected from 150 rice farmers, the research analyzes economic, social, technical, and physical dimensions shaping adaptive responses. Key findings reveal significant regional disparities in adaptive strategies. Alappuzha farmers exhibit greater resilience due to higher incomes, better compensation mechanisms, and stronger community networks. Their strategies primarily involve strengthening bunds, improving drainage infrastructure, adopting flood-resistant rice varieties, and relying on formal credit for support. Conversely, Gondia farmers face lower adaptive capacity, driven by limited access to credit, inadequate compensation, and weaker institutional support. Their climate risk management approaches include drip irrigation, planting drought-resistant crop varieties, and pursuing income diversification to reduce vulnerability. Education levels, access to insurance, and the use of localized weather information also play crucial roles in shaping adaptive capacity across both regions. The study underscores the need for targeted interventions to strengthen institutional support, expand educational programs, facilitate community networks, and improve access to localized weather information to enhance agricultural resilience to climate risks. These findings provide practical policy recommendations aimed at addressing region-specific challenges and leveraging local strengths to bolster adaptive capacity.

A deformability-based mechanical model for predicting shear strength of FRP-strengthened RC beams failed in concrete cover separation

Concrete cover separation (CCS) is frequently happened prior to the yielding of steel stirrups in FRP-strengthened RC beams. However, the debonding mechanism and criterion have not been fully understood. In this study, the typical crack types associated with CCS are comprehensively summarized and investigated in terms of profiles and kinematics of crack. The dowel action and dowelling cracks are proved to be the dominant factors causing CCS. Based on the cracking features, the simplified local debonding strength and average shear strength of fracture interface, which constitutes the contribution of concrete to shear capacity of strengthened RC beams, are analytically derived and verified against the available experiments and code provisions. Through regression analysis of 179 collected shear tests, a formulation based on the Critical Shear Crack Theory (CSCT) is presented to assess the deformability of strengthened RC beams governed by CCS. The commonly overlooked actual stress level in steel stirrups is considered as a function of the rotation capacity of beams and assessed based on the Modified Compression Field Theory (MCFT). Validation of this analytical approach, involving comparison against the empirical models and experimental results from 107 specimens, confirms its superior effectiveness and consistency in predicting CCS and shear strength.

Assessing strength of ferrite and martensite in five dual phase and two martensitic steels via high throughput nanoindentation to elucidate origins of strength

This paper describes the main findings from an experimental investigation into overall and local strength of four dual-phase (DP) steels classified based on their tensile strength (TS) levels from DP590, to 780, to 980, to 1180, a martensitic steel (MS) 1700, and a high-strength low-alloy (HSLA) steel in rolled and additively manufactured (AM) conditions. The DP steels and the MS steel consist of ferrite and martensite, while the HSLA steel is solely martensitic. High throughput nanoindentation mapping is employed to measure the mechanical hardness of individual phases contributing to strength of the steels. A clustering methodology for correlating measured hardness and phase maps is conceived to infer hardness per phase. With increasing fractions of martensite, the hardness values of both ferrite and martensite are found to increase with more rapid increase in the hardness of ferrite than martensite. The phases increasingly dislocate with the fraction of martensite as rationalized by crystal plasticity modeling of strength of the steels. Initial slip resistances and a set of hardening parameters associated with the slip in ferrite and martensite are established to model the flow stress behavior of the steels. In modeling the co-dependent nature of crystallographic slip in ferrite and martensite, the initial dislocation densities are inferred and correlated with the measured hardness values. The hardness of martensite in the rolled HSLA steel is comparable to the hardness of martensite in the MS steel, while martensite in the AM HSLA steel is softer owing to the tempering occurring during the AM process.

Affordances of community-oriented praxis in teacher education: a configurative review

This configurative review explores how nurturing and enacting a community-oriented praxis (COP) in teacher education can enhance teacher candidates’ preparedness for teaching roles whilst addressing some broader educational and societal concerns. Here, CoP is defined as practices that consider, connect with, and draw on local community strengths, needs, and aspirations for the good of individuals, communities, and society more broadly. We review 31 cases in 37 articles on explicitly community-oriented teacher education (COTE) initiatives from nine country contexts where teacher educators, school-based mentors, and members of local communities collaboratively facilitate the learning experiences of participants in teacher education (i.e., teacher candidates). An analysis of the motivations, processes, and outcomes of the initiatives in the COTE cases highlights benefits such as developing teacher candidates’ pedagogical content knowledge and research competence; fostering social justice consciousness and critical action; and facilitating the sustainable recruitment and retention of teachers especially in marginalised contexts. Implications and possible directions for teacher education are discussed.

Evaluation of localized mechanical properties of modified N50 welded joints at cryogenic temperature through a digital image correlation technique

The modified N50 austenitic stainless steel has been determined to be applied as the superconducting magnet supporting material of the Chinese Fusion Engineering Test Reactor (CFETR), especially the jacket material of the CICCs of both the TF coils and the CS coils and the case material of the TF coils, which inevitably requires welding connection. The welding process generally results in welding defects as well as degradation of cryogenic mechanical properties of metallurgical inhomogeneous zones. However, limited research has been reported to demonstrate the distinct localized performance of these zones at cryogenic temperature. The present paper presents an approach to characterize localized mechanical properties of the modified N50 welds at both room temperature (300 K) and cryogenic temperature (6 K). We identified the welding zone (WZ) through metallographic analysis and then the boundaries of the heat-affected zone (HAZ) were recognized by hardness measurements at room temperature. Finally, the localized optical digital image correlation (DIC) technique was used to obtain the localized yield strength Rp0.2 and percentage extension e of the WZ, the HAZ, and the base metal (BM) at both room and cryogenic temperature, of which the observed trend is verified through comparison with that of hardness measurements at room temperature. The technique proposed provides the localized measurement of cryogenic tensile properties of weld metals and also presents experimental data on different zones of the modified N50 welded joints as a jacket material for the next-generation fusion reactors.

Local and nonlocal conditions for electron runaway in a gas gap with a conical cathode with a variable opening angle

The conditions for the generation of runaway electrons in an air gap are compared at different degrees of inhomogeneity of the electric field distribution provided by varying the opening angle of the conical cathode: in the range 40°–120° in experiments and 0°–180° in calculations. It is demonstrated that, in a weakly inhomogeneous electric field (according to the proposed classification, this corresponds to cones with angles greater than the Taylor angle of 98.6°), the runaway condition has a local character. The transition of free electrons into the runaway mode is determined by the local distribution of the electric field near their starting point—the tip of the cone. The local electric field strength must exceed a threshold value comparable to the strength critical for the runaway of electrons in a uniform field. In a strongly inhomogeneous field (cones with angles less than 98.6°), this condition is not sufficient for electrons to run away throughout the gap. Electrons accelerating in the near-cathode region may begin to slow down in a weak field at a distance from the cathode. In this case, the runaway condition becomes nonlocal. It is determined by the dynamics of electrons in the entire gap, primarily in the near-anode region, and reduces to the requirement that the potential difference applied to the gap exceeds a certain threshold value.

Spiking activities in small neural networks induced by external forcing.

Neurons in an excitable mode do not show spiking activity and, therefore, do not contribute to information transfer transmission and its processing. However, some external influences, coupling, or time delay can lead to the appearance of oscillations in individual systems or networks. The main goal of this paper is to uncover the connection parameters and parameters of external influences that lead to the arising of spiking behavior in a small network of locally coupled FitzHugh-Nagumo oscillators. In this study, we analyze the dynamics of a small network in the absence and presence of several types of external influences. First, we consider the impact of periodic-pulse exposure generated as a periodic sequence of Gaussian pulses. Second, we show what behavior can be induced by far less regular pulsed influence (Lévy noise) and its special case called white Gaussian noise. For all types of influences, we have identified the appropriate parameters (local coupling strength, intensity, and frequency) that induce spiking activity in the small network.

Buckling instability analysis of delaminated beam-like structures by using the exact stiffness method

In multilayered structures, delamination not only reduces local strength but also induces buckling instability, compromising structural safety even before reaching the critical buckling load. This paper introduces a novel model for buckling analysis of structures with delamination damage. The model utilizes exact stiffness formulations derived from Timoshenko theory, enabling precising modelling of beam-like structures with through-thickness delamination. The Wittrick-Williams algorithm is utilized to calculate the critical buckling loads, which are validated against results from the finite element software ANSYS. Additionally, a modified Euler buckling formula for the approximate yet closed-form critical buckling load of delaminated beam-like structures is proposed, with comparisons made to the exact stiffness method results. The study investigates the effects of position and length of delamination and boundary conditions of beam on the critical buckling loads. The findings indicate that the buckling reduction factors of delaminated beam is primarily influenced by the thickness-wise position of the delamination, followed by the delamination length, and then the length-wise position of the delamination. Furthermore, the impact of boundary conditions becomes more significant when the delamination is near the beam’s end. This research provides practical guidelines for preventing buckling instability in delaminated beam-like structures.

Research on Indoor Automatic Path Planning Algorithm for Robots

The field of robotics has significantly advanced, especially in indoor autonomous navigation, with applications in households, offices, factories, and tourism. This research focuses on developing and optimizing algorithms for indoor autonomous path planning, aiming to enhance robots' ability to navigate efficiently and safely in various indoor environments. The research adopts a comprehensive methodological approach, beginning with a literature review to understand current state-of-the-art techniques in path planning and obstacle avoidance. Novel algorithms were designed and implemented, focusing on efficiency and real-time performance. These algorithms were tested in simulation environments and validated on actual robotic platforms. Performance metrics such as path efficiency, computational time, and obstacle avoidance success rates were used to assess the algorithms. The study evaluated global path planning algorithms like A* and Dijkstra’s, and local path planning algorithms such as Rapidly-exploring Random Trees (RRT) and Dynamic Window Approach (DWA). A* and Dijkstra's algorithms proved effective for global planning but required optimization for real-time applications. RRT excelled in complex environments but needed improvements for path optimality. DWA provided robust real-time obstacle avoidance. Hybrid approaches combining these algorithms showed enhanced performance, balancing global and local planning strengths. Machine learning techniques further improved adaptability and efficiency. The integration of advanced sensor technologies and accurate map construction methods is crucial for effective indoor navigation. LIDAR, ultrasonic sensors, and depth cameras were key in providing precise environmental perception. Hybrid maps combining grid and topological approaches offered detailed local information and efficient long-distance planning. Optimization techniques like parameter tuning and algorithm fusion, along with machine learning, significantly enhanced algorithm performance. Future research should explore intelligent algorithms, multi-robot collaboration, and human-robot interaction to further advance the field.

Hybrid Additive Manufacturing for Site‐Specific Tensile Response in 316L Stainless Steel

Herein, an alternative way of achieving site‐specific mechanical properties is explored—the hybridization of a directed energy deposition technology with a secondary deformation process (hammer peening (HP)) which acts between deposited layers. By applying the peening in a selective manner, microstructure and hence mechanical properties can be locally varied. Microstructural characterization reveals recrystallization in the HP‐induced deformation zone. The columnar grains of as‐built regions with a grain size of ≈26 μm are transformed into a recrystallized zone with equiaxed grains having a size of ≈8 μm. There is also a highly strain‐hardened region below this recrystallized zone where the dislocation density is more than two times higher than in the as‐built condition. Subsequent tensile testing reveals that these microstructural zones corresponded to local enhancement in tensile strength normal to the build direction. The strengthening mechanisms are identified as Hall–Petch and dislocation (Taylor) strengthening, and their relative contributions are studied. The local strength enhancement comes at the expense of ductility in the build direction, which is studied via finite element modeling and attributed to strain localization into non‐strengthened areas. The results from this work show the possibility of achieving site‐specific properties via interlayer processing.

Modeling of the damage and fracture behaviors of a SiC triplex tube during the burst test with elastomeric insert

The Silicon Carbide (SiC) triplex cladding tube has been regarded as one of the leading structures for the next-generation light water reactors, because of its larger safety margins under beyond-design basis transient conditions. In this study, a numerical simulation method is developed to reproduce the damage and fracture behaviors of a nuclear-grade SiC triplex cladding tube during the burst test. Especially, a three-dimensional continuum damage mechanics based (CDM-based) constitutive model is developed and validated for the SiCf/SiC composites, with the predictions agreeing well with the experimental data under different loading conditions. By introducing cohesive surfaces in the monolithic layers of a SiC triplex tube, cracking of the monolithic layers and the subsequent local damage behaviors within the SiCf/SiC composite layer are captured. The local tensile strength of ∼402 MPa is identified for the monolithic layers, corresponding to the first load drop during the burst test. The simulation results indicate that cracking of the monolithic layers leads to sharp increases in the locally enhanced hoop stresses and damage factors for the SiCf/SiC composite layer, with slight influences on the field variables far away from the main crack; after the fast increase the evolution velocity of local damage factors slows down, reflecting the toughening effects of SiCf/SiC composite. An assessment strategy for the gas leak tightness and structural integrity of the SiC triplex cladding during the accident sceneries is proposed to predict failure of the SiCf/SiC composites with the critical damage factor, and it is necessary to simulate the damage and fracture behaviors in the multi-layer models with the cracking process of monolithic layers involved.

Key stakeholders’ perspectives of illicit drug use and associated harms in the Northern Territory of Australia

BackgroundIn the Northern Territory (NT) of Australia, there are significant evidence gaps about illicit drug use and harms, despite having established monitoring and reporting systems. This paper reports on illicit drug use, associated harms, contributing factors, service needs and priorities in the NT from the perspective and experiences of key stakeholders engaged in providing services for, or advocating on behalf of, people who use illicit drugs in the NT.MethodsFace-to-face and online qualitative interviews were conducted with stakeholders across urban and remote locations in the NT. Key stakeholders were service providers, including acute and primary care clinicians, representatives of Aboriginal community controlled health organisations, lived experience advocates, peak body representatives and public health executives. Qualitative data were analysed thematically.ResultsFour researchers interviewed 21 participants across urban (62%), and remote areas (38%) of the NT. Themes identified were: (1) Illicit drug use and harms are diverse and distinct; (2) Client support needs are complex and influenced by co-morbidities, socio-demographic and cultural factors; (3) Priority population sub-groups need targeted strategies; (4) Local service strengths can be further developed and enhanced; (5) Local services need better resourcing; (6) Invest in progressive legislative and policy reforms; and (7) Improve routine monitoring and evaluation.ConclusionsKey stakeholders described illicit drug use, harms and contributing factors, which provided insights into the local challenges. Participants emphasised that clients have complex care needs, and further investment into targeted strategies are required to improve service engagement with priority groups. Service needs included greater understanding the role of dual diagnosis and its implementation and enhancing integrated and collaborative care in both primary health and acute care contexts. The voices of people with lived experience captured in this paper must inform local strategy and policy development relating to illicit drug use, in alignment with national strategy.

Quantitative measure and visualization for local shock strength in two-dimensional flow

Quantitative measure and visualization for local shock strength in two-dimensional flow

A novel hybrid genetic algorithm and Nelder-Mead approach and it’s application for parameter estimation

Background Traditional optimization methods often struggle to balance global exploration and local refinement, particularly in complex real-world problems. To address this challenge, we introduce a novel hybrid optimization strategy that integrates the Nelder-Mead (NM) technique and the Genetic Algorithm (GA), named the Genetic and Nelder-Mead Algorithm (GANMA). This hybrid approach aims to enhance performance across various benchmark functions and parameter estimation tasks. Methods GANMA combines the global search capabilities of GA with the local refinement strength of NM. It is first tested on 15 benchmark functions commonly used to evaluate optimization strategies. The effectiveness of GANMA is also demonstrated through its application to parameter estimation problems, showcasing its practical utility in real-world scenarios. Results GANMA outperforms traditional optimization methods in terms of robustness, convergence speed, and solution quality. The hybrid algorithm excels across different function landscapes, including those with high dimensionality and multimodality, which are often encountered in real-world optimization issues. Additionally, GANMA improves model accuracy and interpretability in parameter estimation tasks, enhancing both model fitting and prediction. Conclusions GANMA proves to be a flexible and powerful optimization method suitable for both benchmark optimization and real-world parameter estimation challenges. Its capability to efficiently explore parameter spaces and refine solutions makes it a promising tool for scientific, engineering, and economic applications. GANMA offers a valuable solution for improving model performance and effectively handling complex optimization problems.

Molecular dynamics simulation of nanocellulose and cement matrix composites

The interfacial properties of nanocellulose and cement matrix are the key factors affecting the mechanical properties of composite materials. However, it is challenging to study the interface combination through conventional experiments and microscopic characterization techniques. Molecular dynamics simulation (MD), as a nanoscale analytical method, can be used to calculate and analyze the strength, deformation, destruction and interfacial interaction of materials on the atomic scale. Since the existing methods of C-S-H modeling and fiber pull-out from the matrix in molecular dynamics simulations were not suitable for cellulose/C-S-H composite models. In this paper, a molecular dynamics simulation method for nanocellulose cement matrix composites was proposed. Based on the embedded composite model, the tensile stress-strain, interfacial interaction energy, hydrogen bond, and interface failure mode were studied when cellulose was pulled out of the matrix. The results showed that adding cellulose could improve the local ductility and tensile strength of cement matrix materials. The interfacial interaction energy between cellulose and C-S-H was approximately −1.09 J/m2, which was much higher than that between carbon nanotubes and C-S-H. Cellulose would adsorb hydrogen and oxygen atoms on H2O, OH− and silica tetrahedron in C-S-H. In the pull-out simulation of cellulose in C-S-H, C-S-H on the surface of cellulose would be destroyed and attached to the cellulose surface and moved along with it, indicating that cellulose could play a good bridging role in the matrix. The simulation results revealed the action mechanism of cellulose in cement matrix materials.

Study on the delamination damage prediction of wind turbine blade spar cap based on morphology feature recognition

In order to study the degradation of local mechanical properties caused by delamination defects of wind turbine blades, a progressive damage prediction method of blade spar cap based on quantitative identification of delamination morphology features by infrared thermal image was proposed in this paper. Firstly, based on the thermal conduction theory of laminate plates, infrared thermal imaging technology was used to realize quantitatively identify delamination morphology features. Then, based on the cohesive zone model (CZM) and the classical laminate theory (CLT), a numerical analysis model of unidirectional laminate with delamination defects was established, and the accuracy of the numerical model was verified by comparison with the experimental results of axial tensile and compressive displacement loads. Finally, a 2 MW-45.3 blade spar cap with maximum chord cross-section was used as a prediction model, and the effect of different delamination sizes and depths on the failure mode, failure strength and damage evolution of the blade spar cap was successfully predicted by using the equivalent fatigue load. The research shows that the delamination depth has a more profound influence on the damage of spar cap compared with the delamination size. With the increase of delamination depth, the delamination failure modes undergo the evolution process of non-buckling, local buckling, delamination expansion and strength failure. Shallow delamination causes local buckling and strength failure of blade spar cap. When the delamination depth reaches half of the spar cap thickness, the delamination extends to intralaminar and interlaminar, the local failure changes to global failure.