Search results for " Modeling"
showing 10 items of 2411 documents
Universal natural shapes: From unifying shape description to simple methods for shape analysis and boundary value problems
2012
Gielis curves and surfaces can describe a wide range of natural shapes and they have been used in various studies in biology and physics as descriptive tool. This has stimulated the generalization of widely used computational methods. Here we show that proper normalization of the Levenberg-Marquardt algorithm allows for efficient and robust reconstruction of Gielis curves, including self-intersecting and asymmetric curves, without increasing the overall complexity of the algorithm. Then, we show how complex curves of k-type can be constructed and how solutions to the Dirichlet problem for the Laplace equation on these complex domains can be derived using a semi-Fourier method. In all three …
Recent trends in solar exergy and net radiation at global scale
2012
Abstract The availability during the last decades of remotely sensed images and global climatic data allow us to analyse the “Earth system” as a whole in order to develop concepts for global environmental management. This system can be considered a complex, dissipative, dynamic entity, far from thermodynamic equilibrium ( Schellnhuber, 1999 ). Energy balance has been considered for many decades to understand the functioning of ecosystems, the biosphere or the Earth planet as a whole, but it is also possible to study our planet from a thermodynamic point of view. In this letter we analyse recent trends in solar exergy and net radiation at global scale during the period 1980–2010, distinguish…
Performance Analysis of a RED-MED Salinity Gradient Heat Engine
2018
A performance analysis of a salinity gradient heat engine (SGP-HE) is presented for the conversion of low temperature heat into power via a closed-loop Reverse Electrodialysis (RED) coupled with Multi-Effect Distillation (MED). Mathematical models for the RED and MED systems have been purposely developed in order to investigate the performance of both processes and have been then coupled to analyze the efficiency of the overall integrated system. The influence of the main operating conditions (i.e., solutions concentration and velocity) has been quantified, looking at the power density and conversion efficiency of the RED unit, MED Specific Thermal Consumption (STC) and at the overall syste…
Acceptance towards digital health interventions – Model validation and further development of the Unified Theory of Acceptance and Use of Technology
2021
Internet- and mobile-based interventions (IMI) offer an effective way to complement health care. Acceptance of IMI, a key facilitator of their implementation in routine care, is often low. Based on the Unified Theory of Acceptance and Use of Technology (UTAUT), this study validates and adapts the UTAUT to digital health care. Following a systematic literature search, 10 UTAUT-grounded original studies (N = 1588) assessing patients' and health professionals' acceptance of IMI for different somatic and mental health conditions were included. All included studies assessed Performance Expectancy, Effort Expectancy, Social Influence, Facilitating Conditions and acceptance as well as age, gender,…
Situational expectancies and task values: Associations with students' effort
2017
Abstract According to expectancy-value theory, expectancies and task values are precursors for investing effort into learning. To date, it remains largely unknown (1) to what extent expectancies and values change from one learning situation to another and (2) to what extent inter-individual findings reflect intra-individual motivational processes. We applied an intensive longitudinal design in a sample of 155 pre-service teacher students attending a lecture. Across ten lessons with varying topics, students reported three times per lesson on their situational effort, expectancies, task values (intrinsic, attainment, utility), and cost. We used multilevel structural equation modeling with lea…
The role of study engagement in university students' daily experiences: A multilevel test of moderation
2019
The present study investigated the dynamic nature of students' daily experiences and general study engagement using intra-individual assessment. More specifically, we examined individual differences in the relationship between university students' task-specific value and situational emotions and, further, whether first-year study engagement would moderate this association during the first two years of studies. Intra-individual state assessments were conducted via mobile phone-based experience sampling method (ESM) during participants' first (N = 72) and second (N = 56) academic years, resulting in 3089 and 2912 fully completed state questionnaires. In both years, students were asked five ti…
Domestic tourists’ experience in protected natural parks: A new trend in pandemic crisis?
2021
International audience; Since December 2019, the Covid-19 pandemic crisis has led to profound changes around the world with a lot of interdictions or constraints to travel outside one's own country. One of the major consequences has been the development of proximity tourism in outdoor spaces less conducive to the spread of the virus. From a study preceding this pandemic, this article seeks to better understand the experiences lived by domestic tourists when they visited protected natural parks in their country. Beyond the health risks, it analyses the dimensions and the influences of experiences lived in these parks by French domestic tourists (n = 500) using Pine and Gilmore's 4Es model (1…
Entity Recommendation for Everyday Digital Tasks
2021
| openaire: EC/H2020/826266/EU//CO-ADAPT Recommender systems can support everyday digital tasks by retrieving and recommending useful information contextually. This is becoming increasingly relevant in services and operating systems. Previous research often focuses on specific recommendation tasks with data captured from interactions with an individual application. The quality of recommendations is also often evaluated addressing only computational measures of accuracy, without investigating the usefulness of recommendations in realistic tasks. The aim of this work is to synthesize the research in this area through a novel approach by (1) demonstrating comprehensive digital activity monitor…
The risk of sexual-erotic online behavior in adolescents – Which personality factors predict sexting and grooming victimization?
2021
Abstract Information and communication technologies provide new opportunities for adolescents to establish and maintain intimate relationships, as well as exploring their sexuality. However, the young population is particularly vulnerable to becoming victims of violence or online abuse. The aim of this study was to understand to which extent the personality factors (extraversion, narcissism, lack of empathy and disinhibition) are related to sexting and online grooming victimization. The participants were 1763 adolescents between 12 and 16 years (M = 14.56, SD = 1.16, 50.99% girls). A cross-sectional design with self-report data was used, analyzed by structural equation modeling (SEM). The r…
Automatic image-based identification and biomass estimation of invertebrates
2020
1. Understanding how biological communities respond to environmental changes is a key challenge in ecology and ecosystem management. The apparent decline of insect populations necessitates more biomonitoring but the time-consuming sorting and expert-based identification of taxa pose strong limitations on how many insect samples can be processed. In turn, this affects the scale of efforts to map and monitor invertebrate diversity altogether. Given recent advances in computer vision, we propose to enhance the standard human expert-based identification approach involving manual sorting and identification with an automatic image-based technology. 2. We describe a robot-enabled image-based ident…