The Impact of Background Media on Homework Performance: Students’ Perceptions and Experimental Findings

1997 ◽  
pp. 175-189 ◽  
Author(s):  
Johannes W. J. Beentjes ◽  
Tom H. A. van der Voort
Keyword(s):  
Experimental Findings ◽  
The Impact

scholarly journals Quantum plasmonics: from jellium models to ab initio calculations

Nanophotonics ◽  
2016 ◽  
Vol 5 (3) ◽  
pp. 409-426 ◽  
Author(s):  
Alejandro Varas ◽  
Pablo García-González ◽  
Johannes Feist ◽  
F.J. García-Vidal ◽  
Angel Rubio
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Plasmonic Nanostructures ◽  
Functional Theory ◽  
Fundamental Understanding ◽  
Invaluable Tool ◽  
Classical Models ◽  
Light Matter Interaction ◽  
Experimental Findings ◽  
The Impact

AbstractLight-matter interaction in plasmonic nanostructures is often treated within the realm of classical optics. However, recent experimental findings show the need to go beyond the classical models to explain and predict the plasmonic response at the nanoscale. A prototypical system is a nanoparticle dimer, extensively studied using both classical and quantum prescriptions. However, only very recently, fully ab initio time-dependent density functional theory (TDDFT) calculations of the optical response of these dimers have been carried out. Here, we review the recent work on the impact of the atomic structure on the optical properties of such systems. We show that TDDFT can be an invaluable tool to simulate the time evolution of plasmonic modes, providing fundamental understanding into the underlying microscopical mechanisms.

scholarly journals Unsupervised Rank Fusion for Diverse Image Metasearch

2019 ◽  
Author(s):  
José Solenir L. Figuerêdo ◽  
Rodrigo Tripodi Calumby
Keyword(s):  
Image Retrieval ◽  
Search Engines ◽  
Rank Aggregation ◽  
Aggregation Methods ◽  
Experimental Findings ◽  
The Impact

For a given query and a set of images ranked lists retrieved from multiple search engines, the metasearch technique aims at combining these lists to build an unified ranking with improved relevance. Rank aggregation is an approach that has been widely used to support this task. This paper investigates the use of rank aggregation methods in the metasearch scenario for diverse image retrieval. Although metasearch systems are usually driven by the relevance of the final result, the impact on diversification has also been analyzed. The experimental findings suggest metasearch based on rank aggregation allows significant improvements, both in terms of relevance and diversity.

scholarly journals Quasi-Relativistic Calculation of EPR g-Tensors with Derivatives of the Decoupling Transformation, Gauge-Including Atomic Orbitals, and Magnetic Balance

2021 ◽  
Author(s):  
Yannick J. Franzke ◽  
Jason M. Yu
Keyword(s):  
Density Functional ◽  
Hyperfine Coupling Constant ◽  
Basis Set ◽  
Basis Sets ◽  
Generalized Gradient ◽  
Atomic Orbitals ◽  
Experimental Findings ◽  
The Impact ◽  
Derivatives Of ◽  
Magnetic Balance

We present an exact two-component (X2C) ansatz for the EPR g-tensor using gauge-including atomic orbitals (GIAOs) and a magnetically balanced basis set expansion. In contrast to previous X2C and "fully" relativistic ansätze for the g-tensor, this implementation results in a gauge-origin invariant formalism. Furthermore, the derivatives of the relativistic decoupling matrix are considered to form the complete analytical derivative of the X2C Hamiltonian. To reduce the associated computational costs, we apply the diagonal local approximation to the unitary decoupling transformation (DLU) and the (multipole-accelerated) resolution of the identity approximation. The X2C ansatz is compared to Douglas-Kroll-Hess theory and the zeroth-order regular approximation for 11 diatomic molecules. The impact of the relativistic Hamiltonian, the basis set, and the density functional approximation is subsequently assessed for a set of 17 transition-metal complexes to complement our previous work on the hyperfine coupling constant [DOI: 10.33774/chemrxiv-2021-wnz1v-v2]. In total, 24 basis sets and 22 density functional approximations are considered. The quasi-relativistic X2C and DLU-X2C Hamiltonians accurately reproduce the results of the parent "fully" relativistic four-component theory when accounting for two-electron picture-change effects with the modified screened nuclear spin-orbit approximation in the respective one-electron integrals and integral derivatives. Generally, the uncontracted Dyall and segmented-contracted Karlsruhe x2c-type basis sets perform well when compared to large even-tempered basis sets. Moreover, (range-separated) hybrid density functional approximations are needed to match the experimental findings. Here, hybrids based on the meta -generalized gradient approximation are not an a priori improvement. Compared to the other computational parameters, the impact of the GIAOs and the magnetic balance on the actual results in standard calculations is less pronounced. Routine calculations of large molecules are possible with widely available and comparably low- cost hardware as demonstrated for [Pt(C6Cl5)4]− with 3360 basis functions and three spin-(1/2) La(II) and Lu(II) compounds. Both approaches based on a common gauge origin and GIAOs using triple- ζ basis sets lead to a good agreement with the experimental findings. The best agreement is found with hybrid functionals such as PBE0 and ωB97X-D.

Neo-Gricean perspective on irony, deception, and humor vs. some insights from experimental studies

2019 ◽  
Vol 16 (5) ◽  
pp. 591-610
Author(s):  
Agnieszka Piskorska
Keyword(s):  
Theory Of Mind ◽  
Experimental Research ◽  
Experimental Studies ◽  
Comprehensive Model ◽  
Original Theory ◽  
Experimental Findings ◽  
The Impact

AbstractThis article discusses a neo-Gricean approach to irony, deception and humor developed by Marta Dynel, confronting some of its assumptions and implications with results of experimental research. It is stated that Dynel’s modifications and elaborations of Grice’s original theory of conversation improve its coherence and provide adequate methodological tools for a comprehensive model of irony, deception and humor in multi-party interactions, and also for teasing out subtypes of each of these phenomena. Questions regarding the compatibility of this model with experimental findings concern such issues as the relation of irony and deception to Theory of Mind, and the impact of “humor for humor’s sake” on hearers’ opinions. Although these issues are not addressed in Dynel’s philosophically-oriented framework, they are not necessarily incongruent with her perspective.

Stability Study of a Pump-Controlled Circuit for Single Rod Cylinders via the Concept of Lyapunov Exponents

2017 ◽  
Author(s):  
Yuming Sun ◽  
Ahmed Imam ◽  
Christine Wu ◽  
Nariman Sepehri
Keyword(s):  
Stability Analysis ◽  
Lyapunov Exponents ◽  
Controller Design ◽  
Stability Study ◽  
Mode Switching ◽  
Hydraulic Actuator ◽  
Pump Mode ◽  
Mode Of Operation ◽  
Experimental Findings ◽  
The Impact

Pump-controlled hydraulic actuators of single rod cylinders, while efficient, often exhibit undesirable performances during pump mode of operation switching. Although the oscillatory performances have been found in both simulations and experiments, a rigorous proof of such undesirable dynamics has rarely been reported due to lack of proper theoretical tools. In many previous works, traditional stability analysis of pump-controlled single rod hydraulic actuator systems was carried out by studying eigenvalues of the linearized models in each of various regions, separately. This may lead to a conservative conclusion. In this paper, such mode switching instability is analyzed using the concept of Lyapunov exponents. More specifically, the impact of the cracking pressures of the pilot operated check valves on system dynamics of a commonly used pump-controlled circuit is investigated. The numerical results are in agreement with the experimental findings, indicating the efficacy of the proposed method. The paper thus contributes to the systematic stability analysis for non-smooth hydraulic actuator systems, which can subsequently facilitate the controller design.

Consumer perceptions of salesperson gender and credibility: an evolutionary explanation

2014 ◽  
Vol 31 (3) ◽  
pp. 200-211 ◽  
Author(s):  
Gerard Paul Prendergast ◽  
Sze Sze Li ◽  
Connie Li
Keyword(s):  
Purchase Intention ◽  
Phenomenological Study ◽  
Source Credibility ◽  
Internal Validity ◽  
Content Type ◽  
Female Attractiveness ◽  
Additional Support ◽  
Experimental Findings ◽  
The Impact

Purpose – The purpose of this study was to assess the utility of the homophily theory and the related concept of source similarity which predict that a male salesperson is more effective in serving male customers, and a female is more effective with females. For products designed to enhance female attractiveness, however, Darwinian theories of reproduction suggest that a male may be more effective than a female in dealing with female customers. This study of Hong Kong consumers examined the possibility and, in doing so, challenged the assumed utility of homophily in selling cosmetics. Design/methodology/approach – Two studies were conducted. The first was an experiment where female subjects were asked to report their responses to female and male salespersons selling cosmetics. The second study was a phenomenological study exploring the responses of female customers who had encountered male salespeople in cosmetics shops. Findings – The experiment found that a male salesperson tended to induce significantly stronger purchase intention than a female, and that salesperson credibility (specifically, trustworthiness and attractiveness) plays a significant role in mediating the impact of salesperson gender on purchase intention. The follow-up phenomenological study of female customers who had encountered male salespeople in cosmetics shops supported the experimental findings and offered additional support for their evolutionary basis. Research limitations/implications – Darwinian theories of reproduction and source credibility together offer a more complete explanation for the effectiveness of salespeople in the gender-sensitive cosmetics market. However, the experiment involved creating fictitious salespeople matched for trust, expertise and attractiveness. The artificiality of the treatments was necessary to construct a controlled scenario to uphold internal validity, but it may limit the generalizability of the results. Practical implications – To encourage a positive consumer response, retailers need to consider salesperson gender and training. In some specific contexts (such as the selling of products designed to enhance female attractiveness), male salespeople ought to be used ahead of female salespeople, and those male salespeople need to have high credibility to be effective. However, as such, salesmen may not be seen as more expert than saleswomen; expertise needs to be an area of focus in terms of salesperson training. Originality/value – The results of previous research testing homophily theory suggest that a salesperson of the same gender as the customer ought to induce stronger purchase intentions. This study has shown that for the selling of appearance-related products, gender heterophily may be more effective than homophily. Darwinian interpretations of intrasexual rivalry and courtship might help explain why males sell cosmetics more effectively.

Investigation of Fibre Movement in Molten Polymer during Shaping Processes of Thermoplastic Composites

2014 ◽  
Vol 611-612 ◽  
pp. 375-381
Author(s):  
Bernd Engel ◽  
Evelyne Soemer ◽  
Holger Foysi ◽  
Fettah Aldudak
Keyword(s):  
Matrix Material ◽  
Thermoplastic Composites ◽  
Resistance Force ◽  
Fibre Reinforcement ◽  
Molten Polymer ◽  
The Matrix ◽  
Forming Temperature ◽  
Finite Volume Approach ◽  
Experimental Findings ◽  
The Impact

In forming processes of thermoplastic composites, the combined forming behaviour of matrix material and fibre reinforcement determines the resulting geometry and structure. These specific characteristics of the components and their interaction vary during the processing steps, especially for the matrix material with change in temperature. During the forming step, the molten thermoplastic polymer exhibits viscoelastic behaviour. Therefore, the fibres encounter resistance if a forming load is applied. The resulting fibre alignment is dependent on the forming temperature, the forming speed, and the time between the release of load and cooling. An investigation into the specific matrix characteristics during the forming step is presented. In the experiments a representing fibre is drawn through a molten polymer specimen under variation of speed and temperature and the resistance force is measured. The experimental findings are compared to numerical results obtained with a computational fluid dynamics (CFD) package using a finite volume approach and its ability for the prediction of fibre movement in molten matrix during forming processes is evaluated. In addition, a better understanding of the impact of forming speed and temperature during forming processes due to the characteristics of the molten matrix is obtained.

scholarly journals Simulation of Intermittent Turning Processes

1991 ◽  
Vol 113 (3) ◽  
pp. 458-466 ◽  
Author(s):  
G. M. Zhang ◽  
S. Yerramareddy ◽  
S. M. Lee ◽  
S. C.-Y. Lu
Keyword(s):  
Simulation Model ◽  
Initial Value ◽  
Principle Of Superposition ◽  
Practical Applications ◽  
Vibratory Motion ◽  
Intermittent Turning ◽  
Experimental Findings ◽  
The Impact ◽  
Chip Load

A simulation model is developed to study the dynamic characteristics of intermittent turning operations. Factors such as chip load, free-vibration of the toolpost structure, and nonhomogeneous hardness distribution in the material being cut are incorporated in the model. The principle of superposition is used in the formulation of the simulation algorithm. The impact between the cutting tool and the workpiece at the start of every cutting period during machining is treated as an initial value problem. The simulation model provides a quantitative evaluation of the tool vibratory motion during the intermittent turning process. Study of the cutting dynamics based on the simulation results not only confirms the experimental findings, but also indicates that increasing the static stiffness of the toolpost structure is an effective approach to control the tool vibratory motion. The determination of probability of tool breakage under various spindle speed settings is presented as an example to demonstrate the practical applications of the simulation model developed in this work.

scholarly journals Performance Analysis of a Solar Cooling System with Equal and Unequal Adsorption/Desorption Operating Time

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6749
Author(s):  
Farkad A. Lattieff ◽  
Mohammed A. Atiya ◽  
Jasim M. Mahdi ◽  
Hasan Sh. Majdi ◽  
Pouyan Talebizadehsardari ◽  
...  
Keyword(s):  
Cooling System ◽  
Operating Time ◽  
Operating Conditions ◽  
Solar Cooling ◽  
Overall Heat Transfer Coefficient ◽  
Experimental Findings ◽  
Solar Cooling System ◽  
Adsorption Desorption ◽  
The Impact ◽  
Adsorption Systems

In solar-thermal adsorption/desorption processes, it is not always possible to preserve equal operating times for the adsorption/desorption modes due to the fluctuating supply nature of the source which largely affects the system’s operating conditions. This paper seeks to examine the impact of adopting unequal adsorption/desorption times on the entire cooling performance of solar adsorption systems. A cooling system with silica gel–water as adsorbent-adsorbate pair has been built and tested under the climatic condition of Iraq. A mathematical model has been established to predict the system performance, and the results are successfully validated via the experimental findings. The results show that, the system can be operational at the unequal adsorption/desorption times. The performance of the system with equal time is almost twice that of the unequal one. The roles of adsorption velocity, adsorption capacity, overall heat transfer coefficient, and the performance of the cooling system are also evaluated.

scholarly journals Selecting a k-ε turbulence model for investigating n-decane combustion in a diesel engine combustion chamber

2019 ◽  
Vol 7 (2) ◽  
pp. 80-87
Author(s):  
Andrii Avramenko
Keyword(s):  
Numerical Simulation ◽  
Diesel Engine ◽  
Combustion Chamber ◽  
Turbulent Flows ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Toxic Substances ◽  
Engine Combustion ◽  
Experimental Findings ◽  
The Impact

The results of a comparative numerical simulation of combustion and formation of toxic substances in a diesel engine combustion chamber are given. Experimental findings were used to identify the mathematical models. The impact of the standard, RNG and realizable k-ε turbulence models on the accuracy of numerical simulation of combustion and the formation of toxic substances was studied. The realizable k-ε turbulence model was shown to provide a closer agreement of computational and experimental data during simulation of the diesel engine process when turbulent flows are described.

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