A Mixture Explanatory IRT Model for Dynamic Processes

2022 ◽  
pp. 1-1
Author(s):  
Clifford E. Hauenstein ◽  
Susan E. Embretson
Keyword(s):  
Dynamic Processes ◽  
Irt Model ◽  
Explanatory Irt

Surface reactions observed by photoemission electron microscopy (PEEM)

1992 ◽  
Vol 50 (1) ◽  
pp. 286-287
Author(s):  
H.H. Rotermund
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Work Function ◽  
Chemical Reactions ◽  
Reaction Diffusion ◽  
Dynamic Processes ◽  
Clean Surface ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Photoemission Electron

Chemical reactions at a surface will in most cases show a measurable influence on the work function of the clean surface. This change of the work function δφ can be used to image the local distributions of the investigated reaction,.if one of the reacting partners is adsorbed at the surface in form of islands of sufficient size (Δ>0.2μm). These can than be visualized via a photoemission electron microscope (PEEM). Changes of φ as low as 2 meV give already a change in the total intensity of a PEEM picture. To achieve reasonable contrast for an image several 10 meV of δφ are needed. Dynamic processes as surface diffusion of CO or O on single crystal surfaces as well as reaction / diffusion fronts have been observed in real time and space.

The Effect of Alternative Scoring Procedures on the Measurement Properties of a Self-Administered Depression Scale

2019 ◽  
Vol 35 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Noboru Iwata ◽  
Akizumi Tsutsumi ◽  
Takafumi Wakita ◽  
Ryuichi Kumagai ◽  
Hiroyuki Noguchi ◽  
...  
Keyword(s):  
Classical Test Theory ◽  
Depression Scale ◽  
Psychometric Testing ◽  
Epidemiologic Studies ◽  
Test Theory ◽  
Measurement Properties ◽  
Irt Model ◽  
Response Alternatives ◽  
Polytomous Item Response ◽  
Θ Point

Abstract. To investigate the effect of response alternatives/scoring procedures on the measurement properties of the Center for Epidemiologic Studies Depression Scale (CES-D) which has the four response alternatives, a polytomous item response theory (IRT) model was applied to the responses of 2,061 workers and university students (1,640 males, 421 females). Test information functions derived from the polytomous IRT analyses on the CES-D data with various scoring procedures indicated that: (1) the CES-D with its standard (0-1-2-3) scoring procedure should be useful for screening to detect subjects with “at high-risk” of depression if the θ point showing the highest information corresponds to the cut-off point, because of its extremely higher information; (2) the CES-D with the 0-1-1-2 scoring procedure could cover wider range of depressive severity, suggesting that this scoring procedure might be useful in cases where more exhaustive discrimination in symptomatology is of interest; and (3) the revised version of CES-D with replacing original positive items into negatively revised items outperformed the original version. These findings have never been demonstrated by the classical test theory analyses, and thus the utility of this kind of psychometric testing should be warranted to further investigation for the standard measures of psychological assessment.

Modeling Self-Determination Theory Motivation Data by Using Unfolding IRT

2020 ◽  
pp. 1-9
Author(s):  
Philipp A. Freund ◽  
Annette Lohbeck
Keyword(s):  
Ideal Point ◽  
Self Determination Theory ◽  
Self Determination ◽  
Dominance Model ◽  
Irt Model ◽  
Autonomous Behavior ◽  
Location Parameters ◽  
Unfolding Models ◽  
Using Data ◽  
Item Location

Abstract. Self-determination theory (SDT) suggests that the degree of autonomous behavior regulation is a characteristic of distinct motivation types which thus can be ordered on the so-called Autonomy-Control Continuum (ACC). The present study employs an item response theory (IRT) model under the ideal point response/unfolding paradigm in order to model the response process to SDT motivation items in theoretical accordance with the ACC. Using data from two independent student samples (measuring SDT motivation for the academic subjects of Mathematics and German as a native language), it was found that an unfolding model exhibited a relatively better fit compared to a dominance model. The item location parameters under the unfolding paradigm showed clusters of items representing the different regulation types on the ACC to be (almost perfectly) empirically separable, as suggested by SDT. Besides theoretical implications, perspectives for the application of ideal point response/unfolding models in the development of measures for non-cognitive constructs are addressed.

Dynamic processes in dielectric glasses at low temperatures

1982 ◽  
Vol 136 (2) ◽  
pp. 317 ◽  
Author(s):  
B.P. Smolyakov ◽  
E.P. Khaimovich
Keyword(s):  
Low Temperatures ◽  
Dynamic Processes

TO THE STABILITY OF TANK VEHICLES IN THE BRAKE MODE

2019 ◽  
pp. 27-32
Author(s):  
Denys Popelysh ◽  
Yurii Seluk ◽  
Sergyi Tomchuk
Keyword(s):  
Mathematical Model ◽  
Control Systems ◽  
Distribution Systems ◽  
Traffic Accidents ◽  
Road Traffic ◽  
Center Of Mass ◽  
Dynamic Processes ◽  
Course Stability ◽  
The Stability ◽  
Tank Vehicles

This article discusses the question of the possibility of improving the roll stability of partially filled tank vehicles while braking. We consider the dangers associated with partially filled tank vehicles. We give examples of the severe consequences of road traffic accidents that have occurred with tank vehicles carrying dangerous goods. We conducted an analysis of the dynamic processes of fluid flow in the tank and their influence on the basic parameters of the stability of vehicle. When transporting a partially filled tank due to the comparability of the mass of the empty tank with the mass of the fluid being transported, the dynamic qualities of the vehicle change so that they differ significantly from the dynamic characteristics of other vehicles. Due to large displacements of the center of mass of cargo in the tank there are additional loads that act vehicle and significantly reduce the course stability and the drivability. We consider the dynamics of liquid sloshing in moving containers, and give examples of building a mechanical model of an oscillating fluid in a tank and a mathematical model of a vehicle with a tank. We also considered the method of improving the vehicle’s stability, which is based on the prediction of the moment of action and the nature of the dynamic processes of liquid cargo and the implementation of preventive actions by executive mechanisms. Modern automated control systems (anti-lock brake system, anti-slip control systems, stabilization systems, braking forces distribution systems, floor level systems, etc.) use a certain list of elements for collecting necessary parameters and actuators for their work. This gives the ability to influence the course stability properties without interfering with the design of the vehicle only by making changes to the software of these systems. Keywords: tank vehicle, roll stability, mathematical model, vehicle control systems.

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