Experimental determination of rolling element bearing stiffness

In 1990, Lim and Singh presented a complete 6-dof roller-bearing stiffness model. The experimental verification (using an instrumental variables identification procedure) of all the stiffness coefficients of such a bearing appeared to be difficult, because the experimental setup showed some unexpected properties. In this paper the (modified) experimental setup will be presented to get reproducible measurements. Estimating all the stiffness matrix coefficients simultaneously from measured transfer functions still appeared to be unfeasible. Therefore, a 1-dof amplitude fit procedure has been applied. The results appear to be very promising and applicable in practice, but future research certainly is necessary to understand the remaining differences between the mathematical model and measurements. In addition to stiffnesses, the procedure also gives damping values. Finally, matters such as hysteresis, reproducibility and reciprocity have been investigated

Experimental determination of rolling element bearing stiffness

In 1990, Lim and Singh presented a complete 6-dof roller-bearing stiffness model. The experimental verification (using an instrumental variables identification procedure) of all the stiffness coefficients of such a bearing appeared to be difficult, because the experimental setup showed some unexpected properties. In this paper the (modified) experimental setup will be presented to get reproducible measurements. Estimating all the stiffness matrix coefficients simultaneously from measured transfer functions still appeared to be unfeasible. Therefore, a 1-dof amplitude fit procedure has been applied. The results appear to be very promising and applicable in practice, but future research certainly is necessary to understand the remaining differences between the mathematical model and measurements. In addition to stiffnesses, the procedure also gives damping values. Finally, matters such as hysteresis, reproducibility and reciprocity have been investigated

Action Intentions, Predictive Processing, and Mind Reading: Turning Goalkeepers Into Penalty Killers

The key to action control is one’s ability to adequately predict the consequences of one’s actions. Predictive processing theories assume that forward models enable rapid “preplay” to assess the match between predicted and intended action effects. Here we propose the novel hypothesis that “reading” another’s action intentions requires a rich forward model of that agent’s action. Such a forward model can be obtained and enriched through learning by either practice or simulation. Based on this notion, we ran a series of studies on soccer goalkeepers and novices, who predicted the intended direction of penalties being kicked at them in a computerized penalty-reading task. In line with hypotheses, extensive practice in penalty kicking improved performance in penalty reading among goalkeepers who had extensive prior experience in penalty blocking but not in penalty kicking. A robust benefit in penalty reading did not result from practice in kinesthetic motor imagery of penalty kicking in novice participants. To test whether goalkeepers actually use such penalty-kicking imagery in penalty reading, we trained a machine-learning classifier on multivariate fMRI activity patterns to distinguish motor-imagery-related from attention-related strategies during a penalty-imagery training task. We then applied that classifier to fMRI data related to a separate penalty-reading task and showed that 2/3 of all correctly read penalty kicks were classified as engaging the motor-imagery circuit rather than merely the attention circuit. This study provides initial evidence that, in order to read our opponent’s action intention, it helps to observe their action kinematics, and use our own forward model to predict the sensory consequences of “our” penalty kick if we were to produce these action kinematics ourselves. In sum, it takes practice as a penalty kicker to become a penalty killer

Design optimization of multibody systems by sequential approximation

Abstract. Design optimization of multibody systems is usually established by a direct coupling of multibody system analysis and mathematical programming algorithms. However, a direct coupling is hindered by the transient and computationally complex behavior of many multibody systems. In structural optimization often approximation concepts are used instead to interface numerical analysis and optimization. This paper shows that such an approach is valuable for the optimization of multibody systems as well. A design optimization tool has been developed for multibody systems that generates a sequence of approximate optimization problems. The approach is illustrated by three examples: an impact absorber, a slider-crank mechanism, and a stress-constrained four-bar mechanism. Furthermore, the consequences for an accurate and efficient accompanying design sensitivity analysis are discussed

The Cross-Cultural Dementia Screening (CCD):A new neuropsychological screening instrument for dementia in elderly immigrants

Objective: Currently, approximately 3.9% of the European population are non-EU citizens, and a large part of these people are from "non-Western" societies, such as Turkey and Morocco. For various reasons, the incidence of dementia in this group is expected to increase. However, cognitive testing is challenging due to language barriers and low education and/or illiteracy. The newly developed Cross-Cultural Dementia Screening (CCD) can be administered without an interpreter. It contains three subtests that assess memory, mental speed, and executive function. We hypothesized the CCD to be a culture-fair test that could discriminate between demented patients and cognitively healthy controls. Method: To test this hypothesis, 54 patients who had probable dementia were recruited via memory clinics. Controls (N = 1625) were recruited via their general practitioners. All patients and controls were aged 55 years and older and of six different self-defined ethnicities (Dutch, Turkish, Moroccan-Arabic, Moroccan-Berber, Surinamese-Creole, and Surinamese-Hindustani). Exclusion criteria included current or previous conditions that affect cognitive functioning. Results: There were performance differences between the ethnic groups, but these disappeared after correcting for age and education differences between the groups, which supports our central hypothesis that the CCD is a culture-fair test. Receiver-operating characteristic (ROC) and logistic regression analyses showed that the CCD has high predictive validity for dementia (sensitivity: 85%; specificity: 89%). Discussion: The CCD is a sensitive and culture-fair neuropsychological instrument for dementia screening in low-educated immigrant populations.</p

Dementiediagnostiek bij oudere migranten op de geheugenpolikliniek: obstakels en oplossingen

De komende tien jaar verdubbelt het aantal niet-westerse allochtone ouderen. Door specifieke risicofactoren (zoals hypertensie en diabetes) zal het aantal oudere migranten met dementie waarschijnlijk toenemen. Geheugenpoliklinieken zijn onvoldoende voorbereid op deze nieuwe patiëntenstroom, omdat zorgprofessionals onvoldoende kennis hebben van de obstakels die bij interculturele dementiediagnostiek een rol spelen. Zij dienen rekening te houden met taalbarrière, cultuurbarrière, het lage opleidingsniveau en analfabetisme van een aanzienlijk aantal patiënten, maar ook met onbekendheid met dementie, schaamte en bijzondere zorgverwachtingen van de patiënten en hun familie. Er worden aanbevelingen gedaan voor het verbeteren van communicatie, (neuropsychologische) testdiagnostiek en zorgadviezen in de klinische praktijk