Model Theory Research Articles

Random Vibration Fatigue Life Prediction of Nano-Silver Solder Joint

Nano-silver is a very potential electronic interconnection material. It’s excellent physical and chemical properties, high thermal conductivity and good electrical conductivity make it very suitable for high power electronic devices. In practical engineering, 20% of the failure of electronic products is caused by vibration load, so it is necessary to study the vibration reliability of interconnected materials. In this paper, the modal and random vibration finite element analysis of nano-silver solder joints were analyzed with workbench software. Predicting random vibration fatigue life of nano-silver solder joint by Coffin-Manson high cycle fatigue empirical formula, Miner’s linear cumulative damage theory and Steinberg model. The random vibration fatigue life of the nanosilver solder joint is 8342 h. It is found that the vibration reliability of nano-silver is inferior to Sn3.0Ag0.5Cu and Sn63Pb37 and the diameter of solder joints and PCB thickness are proportional to the vibration fatigue life, and the PCB thickness has a greater effect on the vibration life than the solder joint diameter. Solder joint height and pad thickness are inversely proportional to vibration fatigue life, and pad thickness has little effect on vibration fatigue life.

How to restore ecological impacts from wind energy? An assessment of Zhongying Wind Farm through MSPA-MCR model and circuit theory

The wind energy industry is developing rapidly in China with a maximum capacity worldwide. Meanwhile, the stability of the ecological network is challenged by extensive renewable energy expansion. There are still research deficiencies in wind farm ecological impacts at project scale from an ecological restoration perspective. It is of great necessity to monitor the ecological impacts with time going and explore ecological restoration strategies for wind power development. The research case of Zhongying Wind Farm is selected based on investigation and interviews regarding its ecological impact in the prior study. It employs a comparative methodology by comparing the ecological quality before and after the construction of Zhongying Wind Farm. Raw data from Landsat 8, the Digital Elevation Model (DEM), the Normalized Difference Vegetation Index (NDVI), and wind turbine statistics originating from open data platforms are analyzed and visually represented with ArcGIS. This paper establishes an ecological network based on morphological spatial pattern analysis (MSPA) and the Minimum Cumulative Resistance (MCR) model to quantify wind farms’ impacts on ecological corridors. The circuit theory and Pajek software are used to identify and categorize the ecological nodes into weak and obstacle points. The results reveal that ecological impacts on ecological corridors decay with distance, reflecting changes in length, connection strength and cumulative values of corridors. While the impacts on ecological nodes depend on nodes’ attributes: the number of weak points increased by 18.5 %, and obstacle points increased by 350 %, with their locations shifting from the edges of urban construction sites to the edges of wind farm. Differentiated strategies are proposed according to the impact magnitude of each ecological corridor and node: such as dynamic inspection mechanism, construction prohibition for protection; corridor structure and function recovering, stepping stones addition for restoration; buffer belts, warning radar, and monetary schemes for compensation. This research fills the gap of ecological impact assessment under the challenges of wind energy expansion. It helps to balance wind energy development and ecological restoration at the regional level.

Understanding the impact of laziness and pedestrian intervention on car dependence within the context of a European island

Sedentary behaviour, including sitting in motorised vehicles, has been linked with negative physical and psychological health repercussions, even in sufficiently physically active individuals. It is therefore pivotal to identify factors and potential determinants associated with this sedentary behaviour, including the role of the urban environment. Within the plethora of studies analysing habits and experiences as psychological determinants, few have delved into the concept of laziness and car use. This research explores the phenomenon of laziness by measuring people's perceived physical exertion to walk for short-distance trips and applies the ‘Lazy User Theory’ to examine the constructs of people's lazy user behaviour in modal choice. Using questionnaires, interviews and workshops, the paper seeks to understand the link between laziness and car use for short-distance trips by using pedestrian intervention as a tool for analysis. The findings show significant links between higher frequencies of car use and increased perceived exertion of walking for short-distance trips. Although the preliminary application of the Lazy User Theory model was not able to fully explain the behaviour of car-use for short-distance commuting trips, the construct of mental effort provided the best explanation for this behaviour within this context. The paper concludes with policy-relevant feedback from the community on pedestrian interventions to encourage a shift to walking and the next steps for further research into understanding laziness as a determinant of travel behaviour.

Sustainable development and formative evaluation of mathematics open educational resources created by pre-service teachers: an action research study

In the post-pandemic world, UNESCO advocates the development of open educational resources (OER) to remedy the financial pressures of students and their families. We thus conducted a dual-cycle action research study aiming to develop a sustainable model with minimal cost for creating OER for secondary school mathematics teachers and students. Our theoretical foundations drew upon existing sustainable models of OER development and experiential learning theory to enhance the efficacy of OER. Formative evaluation techniques were employed in both action research cycles, where pre-service teachers developed the OER and in-service teachers provided suggestions for improvement. In the second cycle, we tested the use of our OER with 35 Grade 11 students to examine both student achievement and retention. The test results showed a significant learning gain (pre-test: Mdn = 2.00; post-test: Mdn = 10.00), which was retained over 2 weeks (delayed post-test: Mdn = 11.00). However, the students’ performance on more advanced questions was not satisfactory. Based on an overall reflection on the study, we proposed a sustainable model of OER development, which leveraged the manpower of pre-service and in-service teachers and incorporated formative evaluation techniques. Furthermore, we provided recommendations for enhancing the future development of OER in mathematics education.

A python based algorithmic approach to optimize sulfonamide drugs via mathematical modeling

This article explores the structural properties of eleven distinct chemical graphs that represent sulfonamide drugs using topological indices by developing python algorithm. To find significant relationships between the topological characteristics of these networks and the characteristics of the associated sulfonamide drugs. We use quantitative structure-property relationship (QSPR) approaches. In order to model and forecast these correlations and provide insights into the structure-activity relationships that are essential for drug design and optimization, linear regression is a vital tool. A thorough framework for comprehending the molecular characteristics and behavior of sulfonamide drugs is provided by the combination of topological indices, graph theory and statistical models which advances the field of pharmaceutical research and development.

Nonlinear vibration analysis of thin plate with periodically distributed tunable-stiffness nonlinear oscillators in subsonic flow

This paper provides a new passive control method for nonlinear vibration of subsonic thin plates. The control method uses periodically distributed tunable-stiffness nonlinear oscillators (NLO). By using von Karman’s nonlinear plate theory and subsonic aerodynamic model, the nonlinear dynamic model of thin plate is established based on Hamilton’s principle. Through analyzing the system’s nonlinear dynamics bifurcation, the impact of periodic distribution on the stability is discussed. The amplitude-frequency responses are discussed under different NLO installation modes and design parameters by using Matcont software. The results show that the periodically distributed tunable-stiffness nonlinear oscillators can improve the stability of the system and have a remarkable suppression effect. The optimal control scheme for vibration suppression by periodically distributed tunable-stiffness nonlinear oscillators is obtained. The results obtained from this research can offer a valuable understanding of nonlinear vibration control, thereby enabling the identification of various control approaches that can be implemented in practical applications during future design endeavors.

Has climate change promoted the high-quality development of financial enterprises? Evidence from China

Climate change has become a critical global issue and challenge, with significant implications for financial enterprises as an integral part of economic activities. A thorough analysis of the impact of climate change on the high-quality development of financial enterprises is of great importance for financial sustainability. This paper first conducts an in-depth mathematical analysis of the intrinsic mechanisms through which climate change affects the high-quality development of financial enterprises by establishing a game theory model. Secondly, using data from listed companies for the years 2000–2020, an econometric model is constructed to empirically examine the relationship between climate change and the high-quality development of financial enterprises. The research findings demonstrate that climate change significantly inhibits the high-quality development of financial enterprises, as evidenced by robust results obtained through various methods such as data truncation, variable substitution, and changes in sample periods. Furthermore, this study addresses the endogeneity of the regression model using propensity score matching (PSM), instrumental variable methods, and system generalized method of moments (GMM). Additionally, climate change impacts the high-quality development of financial enterprises through technological innovation. Given the backdrop of climate change, understanding the relationship and logic between climate change and the high-quality development of financial enterprises and discerning the channels and mechanisms through which climate change affects their development are crucial. This research provides a new perspective and expands the research frontier on the high-quality development of financial enterprises, enriching the theoretical foundations in this field.

Advancing Fine Branch Biomass Estimation with Lidar and Structural Models.

Lidar is a promising tool for fast and accurate measurements of trees. There are several approaches to estimate aboveground woody biomass using lidar point clouds. One of the most widely used methods involves fitting geometric primitives (e.g. cylinders) to the point cloud, thereby reconstructing both the geometry and topology of the tree. However, current algorithms are not suited for accurate estimation of the volume of finer branches, because of the unreliable point dispersions from e.g. beam footprint compared to the structure diameter. We propose a new method that couples point cloud-based skeletonization and multi-linear statistical modelling based on structural data to make a model (structural model) that accurately estimates the aboveground woody biomass of trees from high-quality lidar point clouds, including finer branches. The structural model was tested at segment, axis, and branch level, and compared to a cylinder fitting algorithm and to the pipe model theory. The model accurately predicted the biomass with 1.6% nRMSE at the segment scale from a k-fold cross-validation. It also gave satisfactory results when up-scaled to the branch level with a significantly lower error (13% nRMSE) and bias (-5%) compared to conventional cylinder fitting to the point cloud (nRMSE: 92%, bias: 82%), or using the pipe model theory (nRMSE: 31%, bias: -27%).The model was then applied to the whole-tree scale and showed that the sampled trees had more than 1.7km of structures on average and that 96% of that length was coming from the twigs (i.e. <5cm diameter). Our results showed that neglecting twigs can lead to a significant underestimation of tree aboveground woody biomass (-21%). The structural model approach is an effective method that allows a more accurate estimation of the volumes of smaller branches from lidar point clouds. This method is versatile but requires manual measurements on branches for calibration. Nevertheless, once the model is calibrated, it can provide unbiased and large-scale estimations of tree structure volumes, making it an excellent choice for accurate 3D reconstruction of trees and estimating standing biomass.

The Nolan Index: An R Program for Calculating List Resemblances

The Nolan Index (NI) is a normed, quantitative measure for comparing the degree of resemblance (similarity or dissimilarity) between free listings with an Excel program for calculating it. This article enhances that effort with the addition of an R program and additional applications. Free-list resemblance measures have been used to investigate and compare historical and cultural connections, ecological relationships, cultural item utilities, practices, knowledge, and values both within and between various groups. Their utility for cultural domain analysis and the theory of cognitive cultural models is also considered.

Effects of transformational leadership on psychological empowerment and employee engagement: a comparative study of Bangladesh and Thailand

Purpose Grounded in the transformational leadership theory, conservation of resource theory and job demands-resources model, this paper aims to examine the effect of transformational leadership on psychological empowerment and employee engagement of faculty members in Bangladesh and Thailand. This study also integrates Hofstede’s cultural dimensions theory to justify whether transformational leadership could affect psychological empowerment of faculty members in these two countries differently. Design/methodology/approach Survey data were collected from a total of 457 faculty members from two universities in Bangladesh (n = 243) and two universities in Thailand (n = 241). This study used partial least squares structural equation modeling for analyzing the proposed model. Findings The evidence shows that faculty members who worked for department heads and who exhibited transformational leadership demonstrated high level of psychological empowerment and employee engagement. Psychological empowerment also mediates the effect of transformational leadership on employee engagement. Moreover, the degree to which transformational leadership positively affects psychological empowerment is stronger for faculty members in a higher power distance culture (Thailand) than for those faculty members in a lower power distance culture (Bangladesh). Practical implications Because human capital plays a crucial role in determining the potential of universities to achieve superior performance, universities should provide leadership training to help department heads understand the key elements of transformational leadership and apply them in their management practices to promote empowerment and engagement of their faculty members. Originality/value The finding provides new evidence that broadens the knowledge from existing research about the cross-cultural effectiveness of transformational leadership, which has not been explored in the area of psychological empowerment.

Psychological responses to political hostility: a study on aggression, bullying, and well-being in Qatar

ABSTRACT In 2017, the Gulf crisis led to a blockade that severely restricted Qatar’s air, land, and sea access. This political crisis had far-reaching consequences, particularly affecting cross-national families and children. This qualitative analysis explores the effects of the blockade’s political instability on individuals and families, specifically for Qatari citizens married to non-Qatari spouses and their cross-national children. Applying the General Aggression Model and Social Learning Theory, we interviewed 24 individuals residing in Qatar from nations directly affected by the crisis (Bahrain, Egypt, Saudi Arabia, and the United Arab Emirates). Two main themes emerged: first, the characteristics of aggressive and bullying behaviour, and second, the impacts on the well-being of cross-national families. The results showed that Qatari women and their children suffered disproportionately due to gender-based citizenship rights issues. The impacts on their well-being included heightened anxiety, depression, feelings of danger, uncertainty, and division within individuals, families, and communities. Recommendations include increasing collaborative efforts between governments, educational institutions, and community-based organizations, which are crucial to addressing aggressive and bullying behaviour across all age groups fostering a more harmonious and resilient society.

GAMBARAN HEALTH BELIEF MODEL PADA PASIEN STROKE DI PENGOBATAN TRADISIONAL USTAD X

Stroke is the third leading cause of death after heart disease and cancer. Although stroke cases are increasing and accompanied by rapid advances in medical treatment, people prefer the use of traditional medicine because the costs incurred are cheaper than medical treatment and they believe that using alternative (traditional) medicine is safer and faster to recover compared to chemical drugs measured through the health belief model theory. The purpose of this study was to look at the description of the health belief model in stroke patients at ustad X's traditional treatment. This study uses descriptive quantitative methods. The population in this study were patients with stroke who sought treatment at Ustadz X Traditional Medicine with a sample size of 32 people. Sampling in this study using non probability sampling technique with accidental sampling type. The results showed that stroke patients at Ustadz X's traditional treatment had a health belief model categorized at a high level both in the perception of vulnerability of 30 respondents (93.8%), perceived severity of 24 respondents (75%), perceived benefits of 31 respondents (96.9%), perceived barriers of 32 respondents (100%), and cues to take action 25 respondents (78.1%).

Formal model theory and higher topology

Formal model theory and higher topology

Comparing the effectiveness of the African Growth and Opportunity Act (AGOA) and Forum on China-Africa Cooperation (FOCAC) in South Africa: An application of Keynes' Macroeconomic Theory

This study applies Keynesian macroeconomic theory in the ARDL model to compare the growth effects of the US's AGOA and China's FOCAC multilateral trading systems in South Africa from the first quarter of 2001 to the fourth quarter of 2022. The study uses South Africa's net exports with the corresponding partner as a proxy for each multilateral trading system. This quantification stems from the fact that South Africa's trade with the US and China has significantly improved since the establishment of AGOA and FOCAC in 2000. Our findings show that none of the multilateral trading systems contribute significantly to South Africa's economic growth. Rather, they appear to be used as strategic initiatives to gain access to mineral resources and facilitate the movement of mining machinery and other inputs into South Africa. To some extent, they are used as market-seeking initiatives, particularly FOCAC. It is worth noting, however, that the mineral resource preferences of these systems vary: while China prioritizes mineral products, the US prioritizes precious metals. This suggests that China and the US scramble for natural resources in South Africa, and possibly Africa in general, is complementary rather than competitive.

A Unified Theory of Acceptance and Use of Technology Assessment in Learning Resources Management and Development System

The platform for Learning Resource Management and Development System (LRMDS) has the potential to be helpful for learning. Teachers find support and resources from the learning portal of the Department of Education. This study focused on determining the acceptance of the Learning Resources Management Development System (LRMDS) as a learning resource portal using the Unified Theory of Acceptance and Use of Technology (UTAUT) model among EPP/TLE/TVL teachers in the Division of Iligan City. For the sample selection based on structures and items, Soper's (2024) a-priori sample size calculator for structural modeling was utilized. This calculator calculates the minimum need to identify desired effects for a structural equation model inquiry by considering variables, effect size, and power levels. The study was based on quantitative and qualitative research designs via demographic questionnaire based on the UTAUT theory model and the perception questions. Findings indicate that the effort expectancy and social influence have positive effects on behavior intentions and facilitating conditions; behavioral intentions also have positive effects on use behavior. However, Performance expectancy is not significant. Additionally, qualitative findings suggest that teachers believe the LRMDS can greatly improve teaching effectiveness when viewed as valuable and dependable, resulting in its effective use. Teachers generally consider the content provided by LRMDS to be relevant and sufficient. However, a significant issue is that some resources, particularly in TLE (Technology and Livelihood Education), are outdated, likely due to limited access to ready-made resources and sufficient learning materials. The findings of this study also suggest that enhancing LRMDS integration, communication and outreach efforts are recommended, including a training guide matrix to raise awareness of LRMDS benefits and address misconceptions through targeted campaigns, workshops, and peer sharing. Recommendations include improving knowledge management, simplifying user interfaces, informing teachers about support conditions, and implementing the training guide matrix in public schools to highlight the advantages of the LRMDS portal.

From ugly to attractive: Leveraging anthropomorphism to increase demand for irregular‐appearing produce

AbstractRecognizing that the waste of imperfect produce contributes to the global environmental crisis, the authors conduct three studies examining whether retailers can use anthropomorphizing marketing techniques to make irregular‐appearing produce more attractive and increase purchase intentions. Based on the exemplar model theory, Study 1 shows that when retailers place googly eyes on pictures of irregular‐appearing produce, consumers judge the product according to multiple exemplars as they do when they evaluate humans. The multiple esthetic cues cause them to perceive irregular produce as more attractive. Study 2 replicates Study 1 by using human names as the anthropomorphic cues, demonstrating that anthropomorphism can increase purchase intentions toward irregular‐appearing produce. Study 3 further shows that the anthropomorphism effects hold for irregular‐appearing produce from corporate farms and not from local farms. The differences occur because consumers expect corporate farms to conform to standardized esthetic norms but expect local farms to market irregular‐appearing produce. When expectations are aligned, anthropomorphism is more likely to cause consumers to diversify esthetic cues, but not when expectations are disassociated. The article concludes with suggestions for promotion strategies that use anthropomorphizing to change attitudes and increase purchase intentions toward irregular‐appearing produce.

Blockchain technology system on student academic performance in higher education as perceived by students in Portugal

ABSTRACT This study conceptually identified the most influential factors from previous studies, which were extracted and classified into contexts based on the technology acceptance model and expectation confirmation theory framework. The purpose of this study is to examine the impact of blockchain system perceived quality and perceived usability on student academic performance (SAP) through the mediating role of student satisfaction and the moderating role of continuance intention. The convenience sampling technique was used to collect data from 583 students studying in different private and public universities in Portugal. Hypotheses were tested using partial least squares-structural equation modeling (PLS-SEM) with SmartPLS software version 4. The findings revealed that the direct effect of blockchain system perceived quality on SAP is positive and significant, while perceived usability is not significant. Moreover, student satisfaction positively and significantly mediates the relationship between perceived quality and SAP, as well as between perceived usability and SAP. Lastly, continuance intention as a moderator has a positive and significant influence on student satisfaction and SAP. The relationship between blockchain system perceived quality, perceived usability on SAP represents a novel contribution through the mediation of student satisfaction and the moderation of continuance intention between student satisfaction and SAP.

Individual random effects model for differences in trait distribution among respondents

The homogeneity hypothesis is a common assumption in classic measurement. However, the item response theory model assumes that different respondents with same ability have the same option probabilities, which may not hold. The aim of this study is to propose a new individual random effect model that accounts for the differences in option probabilities among respondents with same latent traits by using within-person variance. The performance of the new model is evaluated through simulation studies and real data using the PRESUPP scale of PISA. The model parameters are estimated by the MCMC method. The results show that the individual random effect model can provide more accurate parameter estimates and obtain a scale parameter to describe the distribution of respondents’ abilities, under different within-person variances. The new model has lower RMSE and better model fit than the classic IRT model.

Heterotic integrable deformation of the principal chiral model

A novel classically integrable model is proposed. It is a deformation of the two-dimensional principal chiral model, embedded into a heterotic σ model by a particular heterotic gauge field. This is inspired by the bosonic part of the heterotic σ model and its recent Hamiltonian formulation in terms of O(d,d+n)-generalized geometry in Hatsuda [Gauged double field theory, current algebras and heterotic sigma models, ]. Classical integrability is shown by the construction of a Lax pair and a classical R matrix. The latter is almost of the canonical form with a twist function and solves the classical Yang-Baxter equation. Published by the American Physical Society 2024

Sustainability concerns on pro-sustainable travel behavior: combining the United Nations SDGs, norm activation model and value theory

PurposeThis study examines the effect of sustainable development goal (SDG) concerns regarding the sustainability issues raised in the United Nations SDG agenda on pro-sustainable travel behavior (PSTB) by building on the norm activation model as well as value theory (altruism), with the latter assumed to moderate the effect of SDG concerns on PSTB.Design/methodology/approachThe model was tested using structural equation modeling (SEM) based on data from 200 USA respondents who have traveled internationally in the past 12 months.FindingsThe results confirmed the effect of SDG concerns on positively influencing PSTB both directly and indirectly (through the NAM variables of “responsibility” and “obligation”). Additionally, results revealed that altruism positively moderates the effect of SDG concerns on PSTB.Practical implicationsResults provide tourism businesses and destinations with a better understanding of which aspects of the 17 issues identified in the UN SDG agenda are more likely to influence travelers’ future PSTB and whether such behavioral changes additionally depend on people’s individual altruism levels.Originality/valueUnlike previous studies focusing mainly on environmental concerns and tourists’ pro-environmental behavior, this study offers a more comprehensive understanding of PSTB in light of today’s UN SDGs.