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Simulation numérique transitoire de la sollicitation cyclique du contact roue-rail / Transient numerical simulation of wheel-rail contact cyclic loadingSaint-Aimé, Loïc 11 December 2017 (has links)
Sous l’effet des sollicitations mécaniques répétées induites par les passages des trains, on observe l’apparition de fissures de fatigue de contact dans les rails. Une fois amorcées, celles-ci peuvent se propager et mener à la rupture du rail. Dans un contexte d’intensification du trafic, l’optimisation de la politique de maintenance devient stratégique pour les entreprises du transport ferroviaire. Dans ce contexte, un modèle 3D éléments finis du contact roue/rail en courbe a été développé pour reproduire les mécanismes d’amorçage des fissures "Head Check". Ce modèle permet de simuler la sollicitation répétée du contact roue/rail. Cette modélisation a permis d’analyser l’influence de la plasticité sur la distribution de la pression de contact et sur les champs mécaniques résiduels au sein du rail au cours du chargement cyclique. Il ainsi est montré que l’actualisation du contact au cours des chargements répétés est du premier ordre. Les résultats ont permis d’identifier des zones potentielles d’amorçage de fissures de Head Check correspondant à des points matériels sur lesquels la déformation plastique s’accumule de manière considérable. En effet, on observe une correspondance entre ces orientations « accommodées » de la déformation plastique principale et l’orientation des micro-fissures amorcées sur la surface des rails ayant cumulé un faible tonnage (0-10 MGT). Ceci conforte le fait que la méthode proposée est un outil prometteur pour la simulation 3D de la fatigue du contact roue-rail. / As a result of repeated loading induced by train passages, rails are subjected to rolling contact fatigue cracks. Once initiated, cracks could propagate and lead to rail failure. In a context of increased traffic, maintenance policy optimization becomes strategic for railway companies. Thus to define an enhanced planning of maintenance, a better understanding of rail fatigue damage mechanisms is crucial. Under the circumstances, a 3D wheel-rail rolling contact finite element model has been developed in order to reproduce « Head Check » cracks initiation mechanisms. This model allows sequential repeated wheel-rail rolling contact loading. Thus this calculation procedure is used to analyze the influence of plasticity on contact pressure distribution and consequently on residual mechanical fields in the rail during cyclic loading. It is shown that contact conditions evolution during repeated loading must be considered in the first order. The results allowed the identification of potential Head Check cracks initiation zones that correspond to material points on which plastic deformation accumulates significantly. Indeed, there is a correspondence between the « accommodated » principal plastic strain directions and orientation of micro-cracks initiated on rails surface subjected to low cumulative tonnage (0-10MGT). This reinforces the fact that our proposed method is a promising tool for 3D wheel-rail rolling contact fatigue simulation.
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Preliminary study for reference check when used in selection process- Liang Tai, Chia 15 February 2011 (has links)
A reference check is a selection tool that used quite often by employers for identifying their potential employees. It has often been introduced in Human Resource Management textbooks, management articles, or consulting companies¡¦ training courses. However, when compared with other selection tools, a reference check obviously lacks both systematic researches and empirical studies to prove its credibility.
This study is to gain an understanding as to the reason why an employer undertakes a reference check; how employers undertake a reference check and the overall procedure; and the influence and beneficial results of reference check. And I interviewed 12 HR professionals to collect their personal experiences about reference check.
The results show that a reference check is one of the guarantee mechanisms for employers for not hiring an unqualified candidate. Employers take references from referees regarding their comments on applicants, who have already passed several selection processes and selection tools, in order to filter out the applicants who have some unfound problems in precious selection processes or tools. With regards to the hired applicants, employers could understand more about their personalities, strengths and weaknesses from the reference check results.
Normally applicants would not list referees with whom they have had bad relations, so employers might undertake an unofficial reference check through their own personal network to collect information that will not be biased by good relations between applicant and referees. The results also show that some applicants may overestimate their good relationships with their referees, and list the referees who give their negative evaluations on applicants. In general, the referees who are familiar with the applicant, and who are willing to provide a reference along with those who undertake the reference check in a very sensitive manner, are the two key factors that make the reference check work well.
Key word: Reference check, Selection
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Operations training modules for Liberty Check Printers' imprint manufacturing environmentKrautkramer, Carrie A. January 1998 (has links) (PDF)
Thesis--PlanB (M.S.)--University of Wisconsin--Stout, 1998. / Includes bibliographical references.
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The Effects of Behavioral Monitoring Programs on Reading Acquisition of Elementary Students with or At-Risk for Emotional or Behavioral DisorderMorgan, Stacy W. 2009 December 1900 (has links)
The Behavior Education Program was implemented with four students at a large
sub-urban elementary school in central Texas. The elementary school has a diverse
population of 750 students and was implementing Tier 1 interventions with 81% fidelity
as measured by the School-wide Evaluation Tool. The BEP was implemented in a
multiple-baseline design. All students’ behavioral improvement was measured through
daily behavior rating scales, office discipline referrals and time sampling data. Academic
engagement was measured through direct observation, DIBELS progress-monitoring and
nine-week grades. Progress on BEP goals was then compared to direct observation data
of on-task behavior and DIBELS data. All three students’ improvement on BEP goals
correlated with an improvement in academic engagement and increased scoring on
DIBELS progress monitoring indicating that progress in the area of behavior is linked to
academic achievement.
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Evaluating the Effectiveness and Feasibility of Integrating Self-Monitoring into an Existing Tier II Intervention for Elementary School StudentsParry, Michael 29 September 2014 (has links)
Multi-tiered systems of behavioral support are a promising approach for schools looking to maximize their resources while at the same time ensuring that every student's social and behavioral needs are being met. A commonly used Tier II intervention is Check-in/Check-out (CICO), wherein students check in with an adult before and after school and then receive feedback from their teachers throughout the day using a point card. Although CICO has been well supported through previous research, the intervention does require a fair amount of teacher time after each class period, and it also leaves students entirely reliant on the teacher for feedback regarding their behavioral performance throughout the day. The current study therefore examined the effectiveness and feasibility of integrating self-monitoring into CICO, called Student-Guided CICO (SG-CICO). Three elementary students were taught how to self-monitor their behavior after each class and then compare their ratings to those provided by the teacher. Teacher accuracy checks were faded back once students became consistently accurate with their self-ratings. An ABABC single subject design was used to evaluate the effect SG-CICO had on each participant's on-task and disruptive behavior. Each participant displayed (to varying degrees) increased on-task responding and reductions in disruptive behavior following implementation of SG-CICO. Students reported enjoying their participation in SG-CICO, however the acceptability of SG-CICO was met with mixed reactions from staff. Conceptual implications of these results along with a description of study limitations and directions for future research are provided.
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Examining the effects of reciprocal peer-mediated check-in check out with an interdependent group contingencyFaler, Amanda L. 05 October 2021 (has links)
No description available.
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The Micro Check-In Framework for the Next Generation of Location-Based ApplicationsKacha, Shraddha 01 June 2012 (has links) (PDF)
Today's mobile computing platforms provide new, convenient possibilities for location-based commercial activity. In particular, the global positioning system (GPS) provides location data for local advertising and retail activity. In this thesis, we take the next step and introduce the concept of micro check-in. Micro check-in is a simple framework that allows users to match their current location to specific objects or places at a resolution much finer than that allowed by GPS based check-in. We show that micro check-in enables customers to reveal their location at a fine level of granularity. By describing the concepts of points of service, service providers, users, and the enabling technology, we present a generalized, abstract, framework for designing, developing, and analyzing micro check-in based systems.
We discuss several new applications that open up as a result of the combination of real-life and digital communication channel as a result of the micro check-in process. For example, micro check-in could prove quite useful to customers at a restaurant table, a gym equipment station, an exhibit at a museum and many more. This thesis studies micro check-in applied to the process of ordering food from a table at a restaurant and present the beneficial tradeoffs enabled by micro check-in. We find that the micro check-in framework has promising applications in several areas, but specifically utilize the restaurant application, OnTable, to prove the potential use of the micro check-in framework.
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Evaluation of User’s Ability to Adequately Seal Respirator Cartridges/Filters of Differing Size and ShapeRusch, Otto W., III 22 August 2008 (has links)
No description available.
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Validation of the orthogonal dimensions underlying the ICL and the octant constellations assumed to be their measureLange, Donald Edward 01 May 1970 (has links)
Validity of the orthogonal dimensions underlying the Interpersonal Check List (ICL) and the octant constellations assumed to be their measure was investigated by inferential design. Experimental conditions consisted of 4 role-played videotapes produced so that the interpersonal behavior of the main character would illustrate the 4 poles of the ICL’s 2 bipolar dimensions -- Dominance-Submission and Love-Hostility. So were 200 students enrolled in 8 beginning-psychology summer classes. Each class viewed, via closed-circuit TV, only 1 of the 4 videotapes; then members were asked to describe the main character viewed, by using an ICL form IV. Protocols were scored by a computer package of the author's writing. Resulting profiles from classes seeing the same tape were pooled to form 4 treatment groups corresponding to the 4 poles of the ICL then statistically compared by means of a multivariate analogue to analysis of variance. Hypotheses concerning octant constellation comparisons were tested by the Tukey (b) procedure. Results support the assumption that 2 bipolar dimensions underly the ICL and that original formulations of LaForge and Suczek concerning the interpersonal variables taken to be their measure are correct. Results can be taken only as an indirect validation of summary scores Dom and Lov. Differences between these findings and previous published findings were noted and discussed.
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Methodology to determine airport check-in counter arrangementsAhyudanari, Ervina , Civil & Environmental Engineering, Faculty of Engineering, UNSW January 2003 (has links)
Check-in area is an important component of airports. All passengers, except transit passengers and remote check-in passengers, have to enter this area prior to their departure. The convenience for passengers at this area is essential in order to gain more customers using the airports. In estimating the check-in counter arrangements, this thesis introduces a method that is based on spreadsheet software packages. Two programs are developed to assist the optimization computations. The programs provide the optimum number of servers required at the airport. This will help airport management to select the number of counters at a given time. The results of the execution process of these two programs indicate the variables, such as earliness distribution, service time, queue system, and the check in counter sizes and configurations have strong influence to overall cost. A number of applications have been attempted and distribution has been explored. The results also demonstrated that under the condition imposed the multiple queue system provides less maximum queue length but longer waiting time compared to single queue system.
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