First-order Analysis Research Articles

Design of off-axis reflective dual-channel zoom freeform optical systems

In this work, two off-axis reflective dual-channel zoom optical systems are conceived and designed. These two systems achieve good imaging quality and compact system volume by introducing freeform surfaces. Firstly, the system models of the off-axis reflective dual-channel zoom optical systems are introduced, and the first-order analysis is carried out. Then, a design method of an off-axis reflective dual-channel zoom freeform optical system is introduced, and two examples are designed using this method. In one example, the two channels have a separate primary mirror and share a secondary mirror and a third mirror. The system achieves a zoom ratio of 2 times. The two different channels of the other system have separate third mirror and share the primary mirror and the secondary mirror. The system achieves a zoom ratio of 4 times. The two systems have good imaging performance close to the diffraction limit in the visible light band. Finally, the proposed off-axis reflective dual-channel zoom freeform optical system is analyzed and discussed.

First-Order Comprehensive Adjoint Sensitivity Analysis Methodology for Neural Ordinary Differential Equations: Mathematical Framework and Illustrative Application to the Nordheim–Fuchs Reactor Safety Model

First-Order Comprehensive Adjoint Sensitivity Analysis Methodology for Neural Ordinary Differential Equations: Mathematical Framework and Illustrative Application to the Nordheim–Fuchs Reactor Safety Model

Investigation of transverse exchange-springs in electrodeposited nano-heterostructured films through first-order reversal curve analysis

The prerequisite of efficient exchange-spring nano-heterostructures, i.e., tuning both hard and soft phases at a nanometer level, has posed significant preparation challenges to ensure effective exchange-coupling. Here, we present a novel approach to fabricate transverse exchange-spring nano-heterostructures using single starting material through an “in situ” electrodeposition technique at room temperature. Utilizing modified acidic bath chemistry and controlled hydrogen evolution, we successfully prepared stress-free, shiny, fine-grained amorphous, and nanocrystalline Co-rich cobalt phosphorus films. These nano-heterostructured films exhibit a unique non-collinear anisotropy-driven transverse exchange-spring behavior, investigated systematically under ambient conditions. The comprehensive functional analyses reveal that intricate interplay between in-plane (IP) anisotropy of amorphous phase and out-of-plane (OOP) anisotropy generating from a nanocrystalline structure compete with each other, while producing characteristic stripe domain structures to novel corrugated stripe domain shapes. The angle-dependent first-order reversal curve distributions demonstrate new insights into the magnetic reversal mechanisms, further confirming the non-exchange-spring and exchange-spring nature of the films depending on the prevalent interfacial exchange coupling. Formation of anisotropy-driven metastable-state due to competition between IP and OOP anisotropy at a particular OOP orientation has led the normal exchange-spring structures to a transverse exchange-spring structure. Micromagnetic simulations, in excellent agreement with experimental data, further elucidate the formation of characteristic stripe domain patterns and the influence of anisotropy on the magnetic properties. The innovative methodology and detailed functional analysis presented here offer significant understanding to the field of exchange-spring magnetic materials, including anisotropy-driven metastable states, demonstrating the potential for scalable and cost-effective fabrication of advanced nano-heterostructures with tailored magnetic properties.

Comparative study in magnetic properties of FeCo alloy nanowires and a first-order reversal curve analysis

FeCo alloy nanowires have potential applications in data storage, magnetic sensors and spintronic devices. In this paper, FeCo alloy nanowires with varying diameters were fabricated within an anodic aluminum oxide (AAO) template using electrodeposition method at a constant potential. Characterization of the morphology and structure revealed that the polycrystalline body-center-cubic(bcc) FeCo alloy nanowires were obtained. The influence of diameter of FeCo alloy nanowires on magnetic interaction, domain state and magnetic mechanism was investigated through a first-order reversal curve (FORC) analysis. The findings showed that with an increase in the diameter of FeCo alloy nanowires from 20 nm to 60 nm and 100 nm, the interaction force between the FeCo alloy nanowires increased, the domain state of FeCo alloy nanowires changed from Single Domain (SD) to Multi-Domain (MD), the magnetic reversal mode changed from coherent reversal mode to curling reversal mode.

Numerical Simulation for Strength and Stability of RC Tapered Columns

This study investigates the strength and stability of Reinforced Concrete (RC) linearly tapered square columns. Evaluating the slenderness ratio of an RC column requires the radius of gyration of its cross-section, which is well-defined for a prismatic column but not for a non-prismatic one. This study primarily investigates the application of the ACI Code formulae to evaluate the slenderness ratio of RC columns with the studied geometry. Validated numerical models, using Abaqus, were employed to perform nonlinear first- and second-order analyses on the investigated columns subjected to eccentric axial loads. The concrete damaged plasticity model was employed to simulate the nonlinear behavior of concrete. The static Riks solver, available in Abaqus, was utilized for nonlinear analyses: first, with an inactivated geometric nonlinearity for a first-order analysis, and second, with an activated geometric nonlinearity to consider the effects of secondary moments (p-δ effects). The findings indicate the reliability of defining the slenderness ratio of an RC linearly tapered column based on the ACI Code formulae, using the average cross-section of the tapered column.

Secondary school students' perceptions of the 21st -Century 4Cs in Zimbabwe

The volatile, uncertain, complex and ambiguous future world has highlighted the importance of critical thinking, collaboration, communication, creativity and innovation (4Cs) in today’s classrooms. Framed by the Partnership for 21st-Century Learning (P21) Learning and Innovation theme, the study investigates the perceptions of the 4Cs by secondary school students from four schools in Zimbabwe. Two hundred and thirty-six (236) students participated in this quantitative study. Data were collected using online and paper questionnaires. Exploratory and first-order confirmatory analysis revealed a four-factor model with excellent fit indices. The second-order confirmatory factor analysis confirmed that the individual 4Cs were sub-constructs of a higher latent factor, Learning and Innovation (4Cs), where the students strongly endorsed collaboration, followed by communication, critical thinking, creativity, and innovation in decreasing magnitude. Age has a significant influence on critical thinking. The findings highlight the need for teachers to embed critical thinking and creativity acivities within collaborative and communication learning activities.

Relationship Marketing Practices and Export Performance of SMEs in an Emerging Economy: A Mediation Analysis

This inquiry investigated the association between relationship marketing practices-(RMP) and firm performance-(FP) proxy by export performance-(EP) of SMEs in Ghana, utilizing innovation-(INN) and opportunity exploration-(OPE) as mediators. The inquiry espoused a cross-sectional research design, employing SmartPLS-3.3.3 to perform descriptive statistics, principal component analyses-(PCA), exploratory factor analyses-(EFA), reliability/validity analyses, partial least square-structural equation modeling-(PLS-SEM) path analyses via first-order confirmatory factor analysis-(CFA) for testing the hypotheses. Primary data was gathered employing closed-end-(standardized) questionnaires, implementing self-administered, researcher guided face-to-face real-time (immediate) data collection methodology. Secondary data-(financial information) was extracted from annual reports of the SMEs. Complete enumeration was utilized to select all 360 registered SMEs in good standing with the Ghana Enterprise Agency-(GEA) and Association of Ghana Industries-(AGI) forming the sampling frame and sample size. Findings revealed that all seven RMP explanatory variables namely, communication-(COM), adaptation-(ADP), corporation-(COP), trust-(TST), social connections-(SOC), reciprocity-(RCP), relationship quality-(REQ) significantly exerted positive impacts on FP/EP, with REQ exhibiting the most potent predictor, followed by COM, ADP, COP, TST, SOC, and RCP. Again, findings depict that innovation-(INN) and opportunity exploration-(OPE) partially mediated the relationship between RMP and FP/EP. The paper contributes to literature by incorporating the unexplored mediators of INN and OPE, within SMEs in an emerging economy. By establishing connections and suggesting further avenues for research, the paper strengthens its argument both methodologically and conceptually.

Uncertainty analysis on long-term runoff projection from the Budyko framework and a conceptual hydrological model

ABSTRACT Runoff projections are subject to uncertainties related to model structure and parameters. This study aims to analyze uncertainties in long-term runoff estimations from an empirical (Budyko framework) and a conceptual hydrological model (MHD-INPE). Results indicate that both MHD-INPE and Budyko estimations tend to overestimate long-term runoff during years of recurring droughts. Pareto front solutions in MHD-INPE exhibited small uncertainties in long-term runoff estimations regarding parameter calibration (bias between 5 and 7%); differences were observed in low (bellow 5% variation) and high (bellow 10% variation) daily runoff. Related to model structure uncertainties, both models follow similar patterns and performance for a qualitative analysis. Budyko's future projections tend to exceed MHD-INPE's during high precipitation estimates, where at 2000 mm yearly precipitation the estimated runoff from Budyko tends to be 100 mm greater than the hydrological model. Under arid conditions Budyko tends to estimate smaller runoff than MHD-INPE due to variations in soil moisture and water storage not properly represented in Budyko's parameter. Although uncertainties were identified related to model complexity and calibrated parameters, higher uncertainties were identified as related to the climate models. Therefore, the Budyko method is a viable alternative for first-order analysis of long-term impacts.

Rejection of parametric model errors in a recursive Kalman filter for virtual sensing applications

The performance of the Kalman filter is often hindered by the discrepancies between a model used to realize the filter and the true model of the data-generating system. While some methods to account for those errors exists, the majority is restricted to Luenberger's observers. The objective of this work is to develop a Kalman filter where the effect of parametric model errors is rejected from the state and observation equations before the development of the state estimate, and without the explicit knowledge of the error terms. For this purpose, errors in a physical parameter of a parametrized mechanical system are modelled as additive terms in the state and observation equations by means of first-order perturbation analysis. The rejection step is achieved with an injection of a shaped output nullifying the effect of the added terms. A state observer is then derived under the assumption that the injected shaped outputs and the system states are uncorrelated. The performance of the proposed approach is illustrated on an experimental data of a plate system.

Steel ribbed dome structural performance with different node connections and bracing system

The conventional design of steel structure objects relies on a first-order elastic analysis, where the entire object is treated as a set of individual structural elements requiring time-consuming, semi-empirical design calculations. Such an approach leads to inefficient design time and excessive material consumption and may additionally result in designing on the verge of structural safety. The AEC sector's technological and digitization advancement process forces designers to use advanced design methods. Hence, it is necessary to indicate the benefits of using effective optimization. The paper presents a comparative analysis of steel domes using two design approaches: traditional first-order analysis and an advanced second-order analysis. The latter method considers the influence of structural deformation on the magnitude of internal forces. Eight models were developed, varying in terms of the connection's stiffness. The work results identify the differences between the two selected design approaches and present opportunities for further structural performance of steel structures.

Sensitivity analysis and calibration for a two-dimensional state-space model of metal hydride storage tanks based on experimental data

In this paper, a state-space model of a metal hydride tank is formulated and analyzed in detail. Firstly, a three-dimensional state-space model of the metal hydride tank is simplified by assuming that the tank temperature can be measured. Secondly, the model is completed with a pipe model, which allows to compute the input flow from the pipe pressure that can be easily measured. The proposed model solves the problem that the conventional metal hydride tank models usually take the mass flow rate as input and ignore the pressure as system input. Thirdly, the first-order trajectory sensitivity analysis method is adopted to determine the sensitivity of selected unknown parameters. Latter, the particle swarm optimization algorithm is used to estimate the unknown model parameters from experimental data. Finally, a comparison between experimental data and simulation results demonstrates that the proposed model can reflect the dynamic characteristics of the metal hydride tank.

A new model for basic needs: comparison of the second order factorial structures of young schema questionnaire and its relationship with symptoms of psychopathology

This study investigates the structure of Young’s early maladaptive schemas, core emotional needs, and their associations with psychopathological symptoms. Early maladaptive schemas and psychopathological symptoms were assessed in three clinical samples from Turkey (N1 = 1312, N2 = 999, N3 = 999). First-order Principal Component Analysis (PCA) identified 17 schemas, eight of which closely mirrored Young's original schemas. A second-order PCA revealed four schema domains: Impaired Autonomy, Disconnection, Impaired Limits, and Overvigilance. Confirmatory Factor Analyses were employed on distinct samples to compare the PCA model with alternative models, and the PCA model exhibited superior fit across various indices. The study reveals varying relationships between schemas and diverse psychopathological symptoms, providing nuanced insights for tailoring psychotherapeutic strategies and interventions. Symptoms related to interpersonal sensitivity had the strongest connections to schemas, and the factor representing vulnerability to harm and pessimism schemas had the most number of strong connections with psychopathological symptoms. While the study sheds light on the schemas in a Turkish context, future research is essential to validate these findings and explore the predictive aspects of schemas. In essence, this research contributes to understanding of schemas within the Turkish cultural context and its implications for clinical practice.

OPTIMAL LOCATION OF AN IDEAL TRANSFORMER UPFC MODEL USING OPF FIRST-ORDER SENSITIVITIES

This paper presents a screening technique for greatly reducing the computation involved in determining the optimal location of a unified power flow controller (UPFC) in a power system. The first-order sensitivities of the generation cost with respect to UPFC control parameters are derived. This technique requires running only one optimal power flow (OPF) to obtain UPFC sensitivities for all possible transmission lines. To implement a sensitivity-based screening technique for guidance in optimally locating a single UPFC in a power system, we propose a new UPFC model, wrach consists of an ideal transformer with a complex turns ratio and a variable shunt admittance. In this model, the UPFC control variables do not depend explicitly on UPFC input and output currents and voltages. Accordingly, this model does not require adding extra buses for UPFC input and output terminals. IEEE five-, 14- and 30-bus systems were used to frustrate the technique. Index Terms-Flexible ac transmission systems (FACTS), FACTS location, first-order sensitivity, optimal power flow (OPF), screening technique, unified power flow controller (UPFC), UPFC ideal transformer model, UPFC placement, UPFC uncoupled model. This study focuses on the development of an Ideal Transformer Unified Power Flow Controller (UPFC) model and its integration with Optimal Power Flow (OPF) first-order sensitivities analysis for determining optimal UPFC locations in power systems. The abstract outlines the significance of UPFCs in enhancing power system stability and efficiency by controlling voltage and power flow. It highlights the objectives of the research, including the development of the UPFC model, analysis of OPF first-order sensitivities, and their combined application for screening optimal UPFC locations. The study aims to contribute to the improvement of power system operation and control through strategic UPFC placement. The abstract provides a concise overview of the study, summarizing the key aspects of the research. It outlines the development of an ideal transformer Unified Power Flow Controller (UPFC) model, the analysis of Optimal Power Flow (OPF) first-order sensitivities, and their application in determining optimal locations for UPFC installation in power systems

Monte Carlo simulation study on the reliability of concrete-filled HSS beam-column design provisions

Revisions were recently proposed to the way in which concrete-filled hollow structural section (HSS) members are handled in CSA S16. These revisions were based on previous research, comparisons to experiments, and a first-order reliability method analysis of existing provisions for compression and flexural members. In this paper, this topic is further expanded by using Monte Carlo Simulations (MCS) to determine the inherent reliability of the previous and new design rules for concrete-filled rectangular hollow section (RHS) and circular hollow section (CHS) beam-columns. A representative set of concrete-filled RHS and CHS members with variations in concrete strength, wall slenderness, effective length, and loading eccentricity are analyzed. Using MCS, the reliability index (β+) of each is determined over a range of live-to-dead load (L/D) ratios. Inherent β+ values are compared to the code-specified target (i.e., β+ = 3.0 per Annex B of CSA S16) and the CSA S16:19 and AISC 360-16 provisions.

Isogeometric topology optimization of structures using the overweight approach

In this paper, a 2D isogeometric formulation of the material distribution for structural topology optimization considering minimum weight and local stress constraints using the overweight approach is proposed. The aim of this isogeometric formulation is to provide solutions with high spatial definition using a lower number of design variables in comparison with the formulations previously developed to define the material layout. Despite of this, an important number of local stress constraints has to be considered in the solution of the problem. For this purpose, an Overweight Constraint is used to consider all of them. The structural analysis is performed by means of the Isogeometric Analysis (IGA) and the distribution of material is modeled by means of quadratic B-splines. Moreover, the optimization is addressed by means of the Sequential Linear Programming algorithm (SLP) that is driven by the information provided by a full first-order sensitivity analysis extension of the IGA formulation. Finally, the proposed formulation is tested by means of some benchmark problems, and the results show that the isogeometric formulation provides solutions with high spatial definition. A comparison with a Finite Element Method (FEM) topology optimization formulation is included.

Equivalent analysis model of a GaN LED used as a receiver

In general, visible light communication (VLC) uses LEDs as transmitters. However, LEDs can serve as receivers to construct a simple duplex VLC system that uses only two LEDs instead of one LED and one photo-diode (PD). There is a lack of effective equivalent analysis models for characterizing and evaluating the inherent behavioral characteristics of LEDs used as receivers. This paper presents an equivalent analysis model for GaN LEDs as receivers. First, based on the proposed receiving equivalent circuit model, a third-order signal transmission mathematical analysis model is established, revealing the transmission relationship between the photocurrent and output voltage. Further research is conducted on the impact of parameter changes on the bandwidth, and the model can be simplified into a first-order low-pass mathematical analysis model under specific conditions, providing theoretical support for improving the bandwidth of LED receiving applications. The experimental results also confirm the theoretical predictions. This research result holds significant importance for revealing the intrinsic mechanisms and the improved optical communication performance of LEDs for effective reception.

Liver microvascular flow evaluation by texture analysis and quantitative contrast-enhanced ultrasound in pediatric chronic liver disease.

The liver's intricate vascular network is pivotal to its function, requiring a comprehensive understanding for improved diagnostic and treatment strategies in liver diseases. In this pilot study we explore the efficacy of contrast-enhanced ultrasound in identifying microvascular flow in pediatric chronic liver disease (CLD), highlighting the need for objective tools to gain deeper insights. We focused on two novel methods: microvasculature texture analysis and quantitative microvascular flow analysis. CEUS liver images were acquired from 8 patients with CLD related to different etiologies. These images underwent texture analysis, incorporating techniques like first-order histogram analysis, gray-level co-occurrence matrices, and run-length matrix analysis. We also employed a delta projection method to assess microvascular perfusion dynamics. For comparative purposes, liver CEUS images from four healthy individuals were also analyzed. Our texture analysis showed distinct vessel arrangement, and heterogeneity patterns with different liver diseases. For example, patients with primary sclerosing cholangitis exhibited average heterogeneity values of 1411.9. In contrast, those with biliary atresia had different echogenicity heterogeneity (1149.3). The delta projection technique further differentiated microvascular perfusion patterns across liver diseases, with each condition displaying unique perfusion index (PI) and peak enhancement (PE) values. Patients with primary sclerosing cholangitis exhibited comparable perfusion index (PI) values (3.2-3.5) and peak enhancement (PE) values (49.8-53.5). Biliary atresia cases perfusion values were (Pl of 1.3-1.7 and a PE of 40-45.4). Microvasculature texture analysis use is feasible, and with quantitative CEUS analysis, can provide valuable insights into microvascular patterns, enhancing diagnostic precision for pediatric CLD.

Efficacy assessment for multi-vehicle formations based on data augmentation considering reliability

Nowadays, aerial vehicle swarm (AVS) formations have been widely applied to military actions. Meanwhile, assessing their efficacy has also received increasing attention due to the significance for offline tactic planning and online formation switching, which places extra emphasis on the combination of empirical knowledge and experimental data, the transparency of assessment process and the explainability of assessment results. In practical engineering, the efficacy data collected from AVS formations are often incomplete due to limited experiments, and unreliable due to multi-source uncertainties, which poses a great challenge to the development of efficacy assessment system that balances reliability, explainability and accuracy. Oriented to the efficacy assessment of AVS formations under incomplete and unreliable efficacy data, the solution based on belief rule base (BRB) is developed. The reliable heterogeneous data augmentation (RHDA) method is first proposed to improve the availability of efficacy data collected from AVS formation with destination configuration by those collected from AVS formation with source configuration. Then, the feature reliability calculation method based on configuration similarity is designed to avoid the interference of subjective intention. Besides, the configuration importance measurement method based on first-order traceability analysis is put forward to provide decision-makers with references for selecting the most important source configuration when multiple ones exist. The feasibility and effectiveness of developed solution are verified by appropriate simulation experiments.

Evaluating the impact of internet communication quality in human resource management on the productivity of construction projects

This research endeavors to examine the intricate relationship between human resource management and communication management in Iraqi construction projects, exploring their impact on project productivity. Beyond its primary objectives, the study aims to identify key challenges and limitations in implementing effective communication and human resource management practices in the Iraqi construction sector. Understanding these challenges provides valuable insights for practitioners and policymakers, informing strategies to overcome obstacles and enhance project productivity. The research methodology involves an initial survey using a main questionnaire, focusing on three key areas: internet communication in human resource management, the influence of internet quality on construction project management, and factors affecting work productivity. The sample size, determined using Morgan's Table, requires a minimum of 248 participants. The questionnaire is distributed to engineers, managers, and technicians, with the number of respondents meeting the required sample size. Data analysis utilizes the Statistical Package for Social Sciences (SPSS), conducting Exploratory Factor Analysis (EFA) for each variable to identify underlying factors. A first-order confirmatory factor analysis is performed using the Analysis of Moment Structures (AMOS) program, creating a structural model incorporating three variables and their associated factors. Out of the initial 64 factors, 21 are included in the final model, refined based on modification indices (M.I) output to improve fit. Results indicate a significant positive effect (0.92) of internet communication quality on labor productivity, while the impact of labor resource management is relatively negligible (−0.07). The size effect of variables on human resource management is 0.05, suggesting a small but non-zero effect. Overall, the findings underscore the importance of internet communication quality in enhancing labor productivity in construction projects and emphasize the need for effective human resource management practices in the industry. This study contributes valuable insights for project managers and practitioners in construction sector.

The dimensionality of the Conflict Resolution Styles Inventory across age and relationships.

Close interpersonal conflicts between parents and children, marital or romantic partners, and between friends are common, and adjustment in youth and adults depends on how these conflicts are managed. While conflict management is important for relationships and adjustment, the structure of conflict management in adults or in youths has rarely been examined. Knowing how conflict management is structured, and whether this structure changes with age and relationships, is important to understanding what factors influence the development of conflict management skills, and how to intervene. In the current study, we explored the unidimensional vs. multidimensional structure of conflict management in family relationships, friendships and romantic relationships across adolescence and adulthood. The sample consisted of 497 Dutch adolescents (57% boys, Mage = 13.03, SD = 0.46, 11-15 years old) who were followed over 11 years in 9 measurement waves, and their parents, siblings, best friends (six waves), and romantic partner (three waves). First-order factor analyses (CFA) showed that the structure of conflict management is similar for adolescents and adults, across relationships. The results of second-order models, including the theoretical higher dimensions positive/negative conflict management and engagement/disengagement, showed no support for these higher dimensions. The results of bifactor models showed differences between adults and youths: while positive problem solving was part of the general factor of conflict management in adults, it was not part of this general factor in adolescents. The general factor was linked to increases in internalizing and externalizing problems, and with decreases in prosocial behavior. Overall, the bifactor models increased the interpretability and validity of the conflict management measure.