Intercept Factor Research Articles

Latent growth mixture models as latent variable multigroup factor models: Comment on McNeish et al. (2023).

McNeish et al. argue for the general use of covariance pattern growth mixture models because these models do not involve the assumption of random effects, demonstrate high rates of convergence, and are most likely to identify the correct number of latent subgroups. We argue that the covariance pattern growth mixture model is a single random intercept model. It and other models considered in their article are special cases of a general model involving slope and intercept factors. We argue growth mixture models are multigroup invariance hypotheses based on unknown subgroups. Psychometric models in which trajectories are modeled using slope factor loadings which vary by latent subgroup are often conceptually preferable. Convergence rates for mixture models can be substantially improved by using a variance component start value taken from analyses with one fewer class and by specifying multifactor models in orthogonal form. No single latent growth model is appropriate across all research contexts and, instead, the most appropriate latent mixture model must be "right-sized" to the data under consideration. Reanalysis of a real-world longitudinal data set of posttraumatic stress disorder symptomatology reveals a three-group model involving exponential decline, further suggesting that the four-group "cat's cradle" pattern frequently reported is artefactual. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Design modification of elliptical vessel solar receiver by response surface methodology

Design modification of elliptical vessel solar receiver system by response surface methodology has been carried out. The materials used in this study were locally sourced from Kenyeta Market Enugu, Onitsha Bridge Head Market, and Idumota Market Lagos. These materials were sourced based on categories of components element: support mechanisms made of mild steel plates, bolts, nuts, clamps, and water as heat transfer fluid. The reflector is made of aluminum foil tape while the vessel has a glass cover fitted with bolts and nuts, the receiver is made of copper pipe, aluminum pipe, galvanized iron pipes, and stainless steel pipes. The pipes were fitted into the vessel with chlorinated polyvinyl chloride 3⁄4 joint pipes, and journal-bearing mechanisms. Other features include the tracking system made of light dependent resistance sensors, a direct current motor, a pulley, a belt, an Arduino controller, and a thermal energy storage tank. The lagging material was an expanded Polyethylene sheet. Experimental data were measured with thermocouples, a digital panel, a Uni-T digital anemometer (UT363), and a digital solar power meter (SM206-SOLAR). Matrix Experimental design was used to develop an experimental model for the system. The developed system was tested to investigate the effect of various heat collectors with and without coating on its performance. It was established from the response optimization that the intercept factor was improved by 32.2%. Similarly, the theoretical efficiency was improved by 8.19% while the experimental thermal efficiency was improved by 6.99%.

Logistic Regression Analysis: Predicting the Effect of Critical Thinking and Experience Active Learning Models on Academic Performance

<p style="text-align: justify;">This study aims to analyse the relationship between critical thinking and the learning experience provided by instructors through active learning models, specifically Project-based Learning (PjBL) and Simulation-based Learning (SBL), to the potential achievement of academic performance in undergraduate students. The main analysis technique employed in this research was logistic regression, with additional analysis techniques including discriminant validity, EFA, as well as Kendall’s and Spearman’s correlation, serving as a robustness check. The results of this study indicate significant correlations and effects of critical thinking (CT) on academic performance. Higher levels of CT are associated with a greater likelihood of achieving academic excellence, as indicated by the cum laude distinction, compared to not attaining this distinction. Experiences of receiving PjBL (0.025; 6.816) and SBL (0.014; 14.35) predicted the potential for improving academic performance to reach cum laude recognition, relative to not achieving this distinction. Furthermore, other intercept factors need to be considered to achieve cum laude compared to not achieving cum laude. We recommend that policymakers in higher education, instructors, and others focus on enhancing critical thinking and utilizing both Pub and SBL as learning models to improve students’ academic performance.</p>

Development of the Generation 3 Particle Pilot Plant Falling Particle Receiver

A falling particle receiver (FPR) has been designed to integrate with the G3P3-USA pilot plant currently being constructed at the National Solar Thermal Test Facility (NSTTF) at Sandia National Laboratories. This receiver integrates several innovative design features including a converging tunnel (SNOUT), an optimized cavity geometry, and a multistage “catch-and-release” trough. Details about the integration of these features and the final G3P3-USA FPR design and construction are described. Ray-tracing models of the FPR utilizing the NSTTF heliostat field are developed leveraging previous modeling efforts using SolTrace. Models demonstrate that at least 1.5 MWth of incident radiative energy can be provided to the FPR on a clear day throughout a typical year in Albuquerque, NM. Spillage fluxes around the periphery of the aperture are within acceptable bounds for the majority of the year. Intercept factors are computed for each utilized heliostat at the Vernal equinox to provide guidance to heliostat operators during operation of the system.

Latent learning curve of intellectual capital formation in a public university in central Mexico in the face of the pandemic

The latent growth curve is a technique of structural equations which propose that psychological and social phenomena can be modeled in relationships between factors and indicators. The objective of this work was to establish the differences that reflect the learning of the use of anti-pandemic devices. A longitudinal study was carried out from 2020 to 2024 in a sample of 100 students from a public university in central Mexico who were selected from high school to university. The results show that there are differences, but these are not significant. Such findings agree with studies related to stigma towards anti-pandemic policies. In relation to this state of the art, it is recommended to extend the study to the stigma derived from confinement and distancing in order to establish the learning curve of self-care and prevention. The implications of the study on treatment adherence suggest that stigma would be a latent factor that would be mediating the relationship between the intercept factor and the latent slope factor.

Aplanatic solar concentrators for tubular absorbers.

A fundamentally new, to the best of our knowledge, class of linear (2D) dual-mirror aplanats tailored to tubular absorbers is developed for the types of solar concentrators used for thermal power. It is shown that prior investigation establishing this concept possesses unrecognized additional designs, as well as having missed high-performance configurations. It is shown that our line-focus solar concentrators can attain intercept factors exceeding 0.9 at concentration values as high as 55, with practical mirror contours and assemblies. Designed expressly for tubular absorbers, they represent improvements upon previous aplanatic concentrators that were tailored to flat one-sided absorbers but applied to tubular absorbers (as well as to conventional parabolic troughs).

Dimensionality assessment in the presence of wording effects: A network psychometric and factorial approach.

This study proposes a procedure for substantive dimensionality estimation in the presence of wording effects, the inconsistent response to regular and reversed self-report items. The procedure developed consists of subtracting an approximate estimate of the wording effects variance from the sample correlation matrix and then estimating the substantive dimensionality on the residual correlation matrix. This is achieved by estimating a random intercept factor with unit loadings for all the regular and unrecoded reversed items. The accuracy of the procedure was evaluated through an extensive simulation study that manipulated nine relevant variables and employed the exploratory graph analysis (EGA) and parallel analysis (PA) retention methods. The results indicated that combining the proposed procedure with EGA or PA achieved high accuracy in estimating the substantive latent dimensionality, but that EGA was superior. Additionally, the present findings shed light on the complex ways that wording effects impact the dimensionality estimates when the response bias in the data is ignored. A tutorial on substantive dimensionality estimation with the R package EGAnet is offered, as well as practical guidelines for applied researchers.

Does self-affirmation augment the effects of a mandated personalized feedback intervention? A randomized controlled trial with heavy drinking college students.

Theory and evidence indicate that affirming the value of the self before exposure to a threatening message fosters more open-minded appraisal of message content. We predicted that college students mandated to a computer-delivered personalized feedback intervention (PFI) and who engaged in a self-affirmation (SA) exercise would demonstrate reduce drinking and consequences relative to those who received an attention control. Participants were 484 undergraduates (age 18-24, 56% male, 78% White) mandated to participate in an alcohol intervention following a first-time alcohol policy violation. After a baseline assessment, each was randomized to SA (n = 256) or attention control (n = 227) prior to a computer-delivered PFI intervention. Posttest measures included an affirmation manipulation check; primary outcomes (past month weekly quantity, peak drinks, binge frequency, consequences) were assessed at 1-, 3-, 6-, 9-, and 12-month follow-ups. We used latent growth curve modeling to test study hypotheses. The SA exercise increased positive self-evaluation at posttest (p < .001). Overall reductions in drinking and consequences were observed at early follow-up (all p < .05), but the SA manipulation was not associated with intercept or slope factor differences in the models. Engaging in assessments during COVID restrictions was generally associated with reduced drinking and consequences. The SA exercise did not differentially affect trajectories of alcohol use and consequences, despite evidence that the exercise had the predicted effect on participant's self-evaluations. The lack of SA effects could be attributed to a nonthreatening PFI intervention that is generally accepted among mandated students. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Prediction of Circumsolar Irradiance and Its Impact on CSP Systems under Clear Skies

In this work, a model to estimate circumsolar normal irradiance (CSNI) for several half-opening angles under clear skies was developed. This approach used a look-up table to determine the model parameters and estimate CSNI for half-opening angles between 0.5° and 5°. To develop and validate the proposed model, data from five locations worldwide were used. It was found that the proposed model performs better at the locations under study than the models available in the literature, with relative mean bias error ranging from −13.94% to 0.70%. The impact of CSNI for these different half-opening angles on concentrating solar power (CSP) systems was also studied. It was found that neglecting CSNI could lead to up to a 7% difference between the direct normal irradiance (DNI) measured by a field pyrheliometer and the DNI that is captured by CSP systems. Additionally, a case study for parabolic trough concentrators was performed as a way to estimate the impact of higher circumsolar ratios (CSR) on the decrease of the intercept factor for these systems. It was also concluded that if parabolic trough designers aim to reduce the impact of CSNI variation on the intercept factor, then parabolic troughs with higher rim angles are preferred.

A Longitudinal Survey of Job Satisfaction among Pharmaceutical Executives: An Unconditional Latent Growth Curve Study

Cross-sectional studies have been done to explore job satisfaction (JS) among pharmaceutical executives. However, limited evidence of increment or decrement in JS is provided in cross-sectional studies. Latent growth curve models provide a computational framework for evaluating changes in perception and behavior using longitudinal data. Drawing from Locke’s theory of satisfaction, the study explored change in the perception of JS among pharmaceutical executives. To the best of the authors’ knowledge, this is the first study to use a longitudinal design to explore the trajectory of change in JS among pharmaceutical marketing executives using unconditional latent growth curve analysis. Data were collected using an online survey questionnaire from a cohort sample of 1,023 pharmaceutical executives over 3 unequal time waves- T1 (406, June 2021) during COVID-19; and post-COVID periods-T2 (401, July 2022); and T3 (216, March 2023) using random sampling. Covariance-based structural equation modeling in EQS 6.4 was used for analysis. The model showed an acceptable fit. The mean score of JS was significant and positive (Intercept factor; M=2.265, p&lt;0.01). The positive linear growth trend in JS was obtained (growth factor increment=4.594, p&lt;0.01) at each time point. Initial satisfaction states of individual executives were not necessarily linked to changes in mean values over time. The study observed that JS has been on a positive growth trajectory since the COVID-19 pandemic. The study indicates improvement in working conditions by employers since the pandemic and/or coping strategies by employees. This study gives a simple guide to performing latent growth analysis in behavioral research. Keywords: Covid-19, Job satisfaction, Latent growth curve, Locke’s theory of satisfaction, Longitudinal study, Pharmaceutical marketing, Structural equation modeling.

Validación externa y actualización de un modelo predictivo de lesión renal aguda en pacientes adultos hospitalizados en cuidados intensivos

AimTo analyze the predictive performance of the risk model for acute kidney injury (AKI) by Malhotra et al., in adults hospitalized in the intensive care unit (ICU) of Clínica Somer (Colombia), 2017 and 2021. MethodsRetrospective follow-up study of a cohort based on medical records. Critically ill patients over 18 years of age admitted to the ICU were included. Patients with end-stage chronic kidney disease or on renal replacement therapy, AKI at admission were excluded. AKI in the first week in the ICU was defined as the outcome variable, and those of the Malhotra model and additional clinical variables as predictor variables. The predictive performance was analyzed for the original (m0), calibrated (m1–m2) and updated (m3–m6) models using the C statistic, the Hosmer–Lemeshow (HL) test, and calibration maps. ResultsA total of 1235 patients were included, median age 60 years (IQR 45–60), 39.9% women. The incidence of AKI was 30.6%. The original model (m0) showed fit problems (p-HL value <0.05) overestimating the risk of AKI and obtained a C statistic of 0.68 (95% CI: 0.65–0.71). Calibration using intercept and global factor (m2) solved the adjustment problem. The update with ten additional variables (m6) only increased the C statistic to 0.72 (95% CI: 0.69–0.75). ConclusionThe performance of the original model in the external validation cohort is not perfect due to differences in the epidemiology of AKI in the ICU. The model updated improves the fit but not the discrimination, yet it still holds some degree of utility in clinical practice.

Joint Aperture and Power Allocation Strategy for a Radar Network Localization System Based on Low Probability of Interception Optimization

In the process of using the Distributed Radar Network Localization System (DRNLS) further to improve the survivability of a carrier platform, the random characteristics of the system's Aperture Resource Allocation (ARA) and Radar Cross Section (RCS) are often not fully considered. However, the random characteristics of the system's ARA and RCS will affect the power resource allocation of the DRNLS to a certain extent, and the allocation result is an essential factor determining the performance of the DRNLS's Low Probability of Intercept (LPI). Therefore, a DRNLS still has some limitations in practical application. In order to solve this problem, a joint allocation scheme of aperture and power for the DRNLS based on LPI optimization (JA scheme) is proposed. In the JA scheme, the fuzzy random Chance Constrained Programmin model for radar antenna aperture resource management (RAARM-FRCCP model) can minimize the number of elements under the given pattern parameters. The random Chance Constrained Programmin model for minimizing Schleher Intercept Factor (MSIF-RCCP model) built on this basis can be used to achieve DRNLS optimal control of LPI performance on the premise of ensuring system tracking performance requirements. The results show that when RCS has some randomness, its corresponding uniform power distribution result is not necessarily the optimal scheme. Under the condition of meeting the same tracking performance, the required number of elements and power will be reduced to a certain extent compared with the number of elements in the whole array and the power corresponding to the uniform distribution. The lower the confidence level is, the more times the threshold is allowed to pass, and the lower the power is, so that the DRNLS can have better LPI performance.

Design and development of the solar cycloidal thermal concentrator and tapered receiver assembly along with theoretical evaluation of system performance

In this paper, the design and development of a solar cycloidal concentrating system along with utilization of the tapered receiver is presented. For the determination of the performance of the system, theoretical analysis was carried out. The novel concept of utilizing a tapered receiver for a solar cycloidal concentrating system is an innovative approach for this research. After the determination of various parameters for this system, a patent was filed and published under the patent No. 202021028009A on 31 July 2020. For the comparative study purpose, the author has taken three receivers with a constant concentration ratio and different diameters such as .038 m, .031 m, and .025 m. Theoretical evaluation of the system is estimated using modes of heat transfers and using the relation of energy balance. Various correlations are determined for an analytical evaluation purpose. By using graphical collation of all the results for all the three receivers, the author has proposed to use a tapered receiver with the variable CR. CR denotes the concentration ratio. A concentration ratio is defined as the ratio of the area of an aperture to the area of a receiver. In this research, a variable concentration ratio (CR) is used. The receiver used has a diameter which reduces from the inlet to the outlet, and hence, the intercept factor decreases and the concentration ratio increases, leading to an enhancement in efficiency.

Analytic optical evaluation of linear aplanatic solar Fresnel reflectors

Linear Aplanatic Fresnel Reflectors (LAFRs) were recently presented as a novel and viable dual-mirror solar concentrator. Within a vast parameter space, a few promising designs were identified and evaluated via raytracing. This cumbersome, time-intensive exploration left unresolved whether configurations with superior optical performance remained undiscovered. Here, we present analytic methods for all inherent optical losses for the LAFR - results that are equally valid for almost all sources of optical loss in all linear Fresnel reflector solar concentrators. The loss modes include the separate contributions linked to the transverse and longitudinal projected incidence angles. This permits exact rapid comparisons among the wide range of possible aplanatic designs in a physically transparent manner that quantifies each mode of optical loss. These analytic derivations subsume blocking of rays reflected from the primary mirror segments, radiation that misses the primary and strikes the ground, shading of the primary by the secondary, end losses, and rays reflected from the primary that either miss the secondary (spillage) or enter it and miss the absorber tube (ray rejection). LAFR designs superior to those determined previously, in terms of higher intercept factor and higher concentration, are found and evaluated.

Regression-Equivalent Effect Sizes for Latent Growth Modeling and Associated Null Hypothesis Significance Tests

The effect of an independent variable on random slopes in growth modeling with latent variables is conventionally used to examine predictors of change over the course of a study. This article demonstrates that the same effect of a covariate on growth can be obtained by using final status centering for parameterization and regressing the random intercepts (or the intercept factor scores) on both the independent variable and a baseline covariate–the framework used to study change with classical regression analysis. Examples are provided that illustrate the application of an intercept-focused approach to obtain effect sizes–the unstandardized regression coefficient, the standardized regression coefficient, squared semi-partial correlation, and Cohen’s f 2–that estimate the same parameters as respective effect sizes from a classical regression analysis. Moreover, statistical power to detect the effect of the predictor on growth was greater when using random intercepts than the conventionally used random slopes.

An Integration Model for Flux Density Distribution Formed by a Heliostat

An accurate flux density calculation is essential for optimizing and designing solar tower systems. Most of the existing methods introduce multiple assumptions, and the accuracy and scope of the application are limited. This paper proposes an integration model used to calculate the flux density distribution after only applying the Gaussian model for solar brightness distribution. It is the first time that multiple reflections and the influence of the optical error transferred from different planes of the glass mirror are considered in order to build an optical model for the flux density of a heliostat. The reflection from two surfaces of the glass mirror used to form three main parts of beams was considered in the present model, and Fresnel’s equations were applied to calculate the energy of the three parts of reflected rays. An elliptic Gaussian model was applied for the optical error distribution of the heliostat. The model error was evaluated using the experimental data of ten heliostats, and the applicability and accuracy of the model were verified through flux distribution and an intercept factor. The average relative prediction error of the present model from the experimental data was only 2.83%, which is less than SolTrace and other models.

Prospective examination of daily life traumatic stress symptom expression following motor vehicle collisions.

Motor vehicle collisions (MVCs) are a common source of traumatic stress, which could lead to the development of posttraumatic stress disorder. However, the natural course of symptom development is still poorly understood. The current study aimed to prospectively examine the expression of traumatic stress symptoms in mild-moderate injured MVC survivors, using a novel daily life repeated measurement approach. Participants (N = 70) were screened and recruited upon hospital arrival. Daily assessments of traumatic stress symptoms were conducted via mobile phones, and the data during days 2-6 (acute phase) and 27-31 (1-month phase) following the MVC were used for the current study. Latent growth curve analyses showed that at the acute phase, traumatic stress symptoms followed a reducing trajectory, with significant intercept and negative slope factors. At the 1-month phase, traumatic stress symptoms followed a low-stable trajectory, with a lower intercept and a nonsignificant slope factor. The acute-phase intercept and slope were both positively associated with 1-month symptomatology, such that higher initial symptoms and slower recovery rates were associated with greater traumatic stress symptoms at 1-month post-MVC. Trauma history and peritraumatic perceived life threat were indirectly associated with the 5-days end-of-the-month traumatic stress symptoms, through the mediation of the acute-phase intercept. An early screen of traumatic stress symptoms in the first few days following trauma exposure, together with trauma history and perceived peritraumatic life threat, may assist in identifying individuals at risk for subsequent posttraumatic psychopathology. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Modeling the external flow of a novel HorseShoe receiver and the evaluation of thermal performance

The linear receiver of a Parabolic Trough Collector is the most critical element in the entire system. The Universal Vacuum Air Collector concept is the most extended type of receiver in both experimental and industrial facilities. Besides their considerable cost, their efficiency usually drops as operation time passes. This is mainly due to a partial loss of vacuum in the evacuated annulus between the absorber and the glass cover. An alternative design called HorseShoe receiver is proposed in this work, whose main goal is to maintain the thermal performance throughout its entire lifespan. This innovative receiver is indicated for low-to-medium temperature ranges, which is particularly suitable for solar heat for industrial processes. It consists of a horseshoe-like cavity absorber having its upper border insulated. In addition, two main advantages can be taken by using two symmetric lenses as glass cover: reconcentrate solar radiation into the cavity (improvement of the intercept factor) and protect stratification conditions (reduction of thermal losses). A transient numerical model with customized boundary conditions has been implemented to evaluate both thermal performance and temperature difference in the absorber domain, which is critical for the thermal stress conditions. For that purpose and as a key contribution, not only the Heat Transfer Fluid (HTF) temperature but also the heat transfer coefficient in the duct are set. In particular, HTF temperature ranges from 80 °C to 220 °C and the inner heat transfer coefficient from 600 W/(m 2 ⋅ K) to 1800 W/(m 2 ⋅ K). Results show that numerical thermal performance is above 96%, which is mainly due to the reduction of thermal radiation losses, where the absorber active surface emittance is ϵ a b s = 0 . 3 . Since no inclination of the receiver has been considered in this initial study, it is shown that the air inside the cavity is stratified, which reduces convective losses. Moreover, temperature difference between the coldest and the hottest spot of the absorber is no higher than 30 K, which is affordable from a technical point of view. A polynomial heat losses correlation is also provided, whose parameters are on the same order of those by conventional receiver correlations available in the literature. • A new concept of solar linear cavity receiver (HorseShoe receiver) is proposed. • Thermal losses have been evaluated numerically. • Thermal performance is above 96% under the selected operation conditions. • The symmetric lenses enhance air stratification. • Most of the thermal losses are due to thermal radiation.

Study on the influence of dust accumulation on the photothermal performance of a trough solar system based on space-time factors in alpine areas

Based on the dust accumulation and distribution characteristics of concentrator surfaces in alpine regions, a comparative experimental platform for measuring the energy flux density of the focal plane and thermal performance was developed in this study. By combining theory and experimentation, the influence of time (dust deposition density) and space (concentrator tilt angle) on the dust distribution characteristics and photothermal performance of a trough solar system was studied. The optical loss caused by concentrator dust was evaluated based on the intercept factor, while the thermodynamic loss caused by dust was evaluated based on the collecting efficiency and exergy efficiency. The results demonstrate that concentrator dust at a tilt angle of 60° will lead to a maximum center shift of 1.66 mm of the focal plane. Importantly, the inconsistency between thermal performance and dust deposition density indicates that the dust distribution characteristics caused by tilt angle have a significant influence on the thermal performance of the system. Comparatively, an increase in dust deposition density from 0 to 2.46 g/m2 leads to a 20.58% relative reflectivity loss, together with 48.30% and 55.08% reductions in the collecting efficiency and exergy efficiency, respectively. This study revealed the influence of space–time factors on dust distribution characteristics and photothermal performance, which can provide design ideas regarding dust removal for the application of trough solar systems in alpine areas.

Laser Profilometry on Micro-PTC

Profilometry is useful in detecting surface faults on solar concentrators, which can be imperfectly manufactured, thus affecting system performance. Profilometric analyses are performed on a micro-parabolic trough collector (m-PTC), with reduced sizes and greater mirror curvature than a usual PTC. The peculiar dimensions and shape of this micro-PTC request to develop a specific configuration of laser profilometry. It includes a laser diode with a converging lens placed in front of it, ensuring that the mirror curvature does not affect the beam reflection. A new method to calculate the spot position furnishes the reflected beam center even if it lies outside the target, giving it a virtual expansion. The profile is assessed with an iterative calculation, starting from a first point, physically measured. The results are the 3D profile reconstruction of the parabolic mirror and a map of the slope error for each mirror point. It also estimates the intercept factor, a parameter fundamental to optimize the m-PTC system, whose value is in agreement with a structured light measurement on the same object. This intercept factor was obtained averaging the local intercept factor calculated for each mirror point, which individuates the mirror portions not focusing the sunrays on the tube.