Search results for "Variable"
showing 10 items of 1674 documents
Emotional and behavioral problems in children with attention deficit-hyperactivity disorder: Impact of age and learning disabilities
2008
Comorbidity with other psychological problems (PP) complicates the course of attention deficit-hyperactivity disorder (ADHD) and makes treatment more difficult. The purpose of the present study was to (a) study the correspondence between the perceptions of parents and teachers about PP, (b) determine which PP predict the severity of the manifestations of ADHD, and (c) analyze the role of age and learning disabilities (LD) in the development of PP and ADHD. The participants were 72 children with a clinical diagnosis of ADHD. The PP were measured using rating scales filled out by parents and teachers. The results showed high correspondence between the two informant groups in rating the probl…
Instructional support predicts children’s task avoidance in kindergarten
2011
Abstract This study examined the role of observed classroom quality in children's task-avoidant behavior and math skills in kindergarten. To investigate this, 1268 children were tested twice on their math skills during their kindergarten year. Kindergarten teachers ( N = 137) filled in questionnaires measuring their professional experience and also rated the children on their task-avoidant versus task-focused behaviors. Trained observers used the CLASS instrument ( Pianta, La Paro, & Hamre, 2008 ) to observe 49 kindergarten teachers (out of 137) on their emotional support, classroom organization, and instructional support. The results of multilevel modeling showed that kindergarten classro…
The Antecedents of Customer Loyalty - Results of an Empirical Study in the Automotive Industry
2015
Customer satisfaction is regarded as the key to customer loyalty in the automotive industry. However, this relationship is influenced by several other variables, like switching barriers or variety seeking. This paper provides a structural equation model with latent variables for modeling this complex relationship. According to literature, high satisfaction should lead to loyalty but is heavily affected by moderating variables. An empricial study is reported which supports these predictions as well as the arguments on which they are based.
Knowledge creation. The ongoing search for strategic renewal
2014
Purpose– The purpose of this paper is to analyse how changes in a set of structural design variables (i.e. liaison position, networked design, innovation teams and work teams) affect the creation of new knowledge within organizations. The enablers intention, autonomy, fluctuation and creative chaos, redundancy, variety, and trust and commitment, taken from Nonaka's framework, are used as intermediate variables.Design/methodology/approach– A sample of 167 large Spanish companies was used to empirically test a general relational model.Findings– The analysis yielded two main conclusions. First, the relationship between structural variables and enablers, and, second, the relationship of enabler…
Conceptual design of prestressed slab bridges through one-way flexural load balancing
2013
In this paper a study on prestressed concrete slab bridges is presented. A design philosophy based on the concept of load balancing through prestressing is proposed in order to minimize the effects of delayed deformations due to creep. Aspects related to the stress redistribution inside these bridges for time-dependent phenomena are analyzed and discussed, by applying the principles of aging linear visco-elasticity. Prestressing is seen as an equivalent external load which counterbalances the permanent loads applied to the bridge, nullifying the elastic deflections due to sustained loads, and thus avoiding the related delayed deformations. An optimization of the structural behavior through …
Control strategy analysis of the hydraulic hybrid excavator
2015
Abstract Applying the electric hybrid technique on the off-road vehicle is one popular method to reduce the fuel consumption. However, the high cost, low energy conversion efficiency and disposal of used batteries are still the main problems. This paper is focusing on one alternative choice which is hydraulic hybrid off-road vehicles. Among the most typical off-road vehicles, the excavator is chosen as the prototype to study the control strategy. First, the basic principle of the hydraulic hybrid excavator based on Common Pressure Rail is introduced. Then, the mathematical model of the whole excavator is created. Moreover, the dynamic programming algorithm is used to solve the optimal contr…
Scalable and Privacy-Preserving Admission Control for Smart Grids
2015
International audience; Energy demand and production need to be constantly matched in the power grid. The traditional paradigm to continuously adapt the production to the demand is challenged by the increasing penetration of more variable and less predictable energy sources, like solar photovoltaics and wind power. An alternative approach is the so called direct control of some inherently flexible electric loads to shape the demand. Direct control of deferrable loads presents analogies with flow admission control in telecommunication networks: a request for network resources (bandwidth or energy) can be delayed on the basis of the current network status in order to guarantee some performanc…
A systematic approach for fine-tuning of fuzzy controllers applied to WWTPs
2010
A systematic approach for fine-tuning fuzzy controllers has been developed and evaluated for an aeration control system implemented in a WWTP. The challenge with the application of fuzzy controllers to WWTPs is simply that they contain many parameters, which need to be adjusted for different WWTP applications. To this end, a methodology based on model simulations is used that employs three statistical methods: (i) Monte-Carlo procedure: to find proper initial conditions, (ii) Identifiability analysis: to find an identifiable parameter subset of the fuzzy controller and (iii) minimization algorithm: to fine-tune the identifiable parameter subset of the controller. Indeed, the initial locatio…
Capacity and safety analysis of hard-shoulder running (HSR). A motorway case study
2016
Abstract Operational motorway conditions can be improved by introducing traffic flow management and control systems, such as ramp metering (RM), high occupancy vehicle (HOV) lanes, real-time variable speed limits (VSLs), reversible lanes (RL), automated highway systems (AHS) and hard-shoulder running (HSR). The effects of such devices need to be examined in terms of capacity and safety. This paper examines the case study of the Italian motorway A22, which is supposed to be equipped with an HSR system implemented along 128 km in order to reduce congestion with consequent improvement in levels of service (LOS). We studied the traffic processes (capacity, flow distribution between lanes, relia…
Unified formulation for a family of advanced finite elements for smart multilayered plates
2016
AbstractFamilies of layer-wise and equivalent single-layer advanced finite elements for the analysis of smart multilayered plates are formulated in a unified framework. The proposed modeling strategy reduces the multifield problem to an effective mechanical plate by the condensation of the electromechanical state into the plate kinematics, which is assumed as a variable order expansion along the plate thickness. Carrera Unified Formulation is invoked to derive the elemental stiffness and mass matrices and the mechanical and magneto-electric equivalent forces. The obtained smart plate finite element equations involves kinematical variables only and this extends the tools developed for multil…