重构 荷兰乌得勒支大学图书馆

<正>乌得勒支大学(Utrecht University),作为荷兰最好的3所大学之一,也是所有13所大学中历史最悠久的一所。悠久的历史成就了该校深厚的文化底蕴,也成为他们不断发展的坚实基础。在校园的规划与建设上,该校一直走在时代前列。早在     

Do drivers change their manual car-following behaviour after automated car-following?

There is evidence that drivers’ behaviour adapts after using different advanced driving assistance systems. For instance, drivers’ headway during car-following reduces after using adaptive cruise control. However, little is known about whether, and how, drivers’ behaviour will change if they experience automated car-following, and how this is affected by engagement in non-driving-related tasks (NDRT). The aim of this driving simulator study, conducted as part of the H2020 L3Pilot project, was to address this topic. We also investigated the effect of the presence of a lead vehicle during the resumption of control, on subsequent manual driving behaviour. Thirty-two participants were divided into two experimental groups. During automated car-following, one group was engaged in an NDRT (SAE Level 3), while the other group was free to look around the road environment (SAE Level 2). Both groups were exposed to Long (1.5 s) and Short (.5 s) Time Headway (THW) conditions during automated car-following, and resumed control both with and without a lead vehicle. All post-automation manual drives were compared to a Baseline Manual Drive, which was recorded at the start of the experiment. Drivers in both groups significantly reduced their time headway in all post-automation drives, compared to a Baseline Manual Drive. There was a greater reduction in THW after drivers resumed control in the presence of a lead vehicle, and also after they had experienced a shorter THW during automated car-following. However, whether drivers were in L2 or L3 did not appear to influence the change in mean THW. Subjective feedback suggests that drivers appeared not to be aware of the changes to their driving behaviour, but preferred longer THWs in automation. Our results suggest that automated driving systems should adopt longer THWs in car-following situations, since drivers’ behavioural adaptation may lead to adoption of unsafe headways after resumption of control.

     

Guaranteeing prescribed performance and contact maintenance via an approximation free robot force/position controller

In this paper, we consider the problem of force/position tracking for a robot with revolute joints in compliant contact with a kinematically known planar surface. A novel controller is designed capable of guaranteeing, for an a priori known nonsingular initial robot condition, (i) certain predefined minimum speed of response, maximum steady state error as well as overshoot concerning the force/position tracking errors, (ii) contact maintenance and (iii) bounded closed loop signals. No information regarding either the robot dynamic model or the force deformation model is required and no approximation structures are utilized to estimate them. As the tracking performance is a priori guaranteed irrespectively of the control gains selection, the only concern is to adopt those values that lead to reasonable input torques. Finally, a comparative simulation study on a 6-DOF robot illustrates the performance of the proposed controller.     

Charge transport mechanisms and memory effects in amorphous TaNx thin films

Amorphous semiconducting materials have unique electrical properties that may be beneficial in nanoelectronics, such as low leakage current, charge memory effects, and hysteresis functionality. However, electrical characteristics between different or neighboring regions in the same amorphous nanostructure may differ greatly. In this work, the bulk and surface local charge carrier transport properties of a-TaN_x amorphous thin films deposited in two different substrates are investigated by conductive atomic force microscopy. The nitride films are grown either on Au (100) or Si [100] substrates by pulsed laser deposition at 157 nm in nitrogen environment. For the a-TaN_x films deposited on Au, it is found that they display a negligible leakage current until a high bias voltage is reached. On the contrary, a much lower threshold voltage for the leakage current and a lower total resistance is observed for the a-TaN_x film deposited on the Si substrate. Furthermore, I-V characteristics of the a-TaN_x film deposited on Au show significant hysteresis effects for both polarities of bias voltage, while for the film deposited on Si hysteresis, effects appear only for positive bias voltage, suggesting that with the usage of the appropriate substrate, the a-TaN_x nanodomains may have potential use as charge memory devices.     

Patients admitted to psychiatric hospital: Presenting problems and resolution at discharge.

Examined a cohort of admissions (N?=?280) to a 150-bed public psychiatric hospital to investigate homogeneity in patient problems and patient subtypes. The interrelationships of presenting problems, treatment provided, length of stay, resolution of presenting problems, and several other variables were also studied. Results indicated that many problems experienced by patients were not psychiatric symptoms. Most presenting problems were addressed but few resolved. The primary form of treatment was psychotropic medication. Many patients were discharged before treatment effectiveness was determined. Little association was found between diagnosis, patients' problems or patient subgroup, and psychotropic drugs prescribed. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Force/position tracking for a robotic manipulator in compliant contact with a surface using neuro-adaptive control

The problem of force/position tracking for a robotic manipulator in compliant contact with a surface under non-parametric uncertainties is considered. In particular, structural uncertainties are assumed to characterize the compliance and surface friction models, as well as the robot dynamic model. A novel neuro-adaptive controller is proposed, that exploits the approximation capabilities of the linear in the weights neural networks, guaranteeing the uniform ultimate boundedness of force and position error with respect to arbitrarily small sets, plus the boundedness of all signals in the closed loop. Simulations highlight the approach.     

Ferromagnetism above room temperature in bulk and transparent thin films of Mn-doped ZnO

The search for ferromagnetism above room temperature in dilute magnetic semiconductors has been intense in recent years. We report the first observations of ferromagnetism above room temperature for dilute (<4 at.%) Mn-doped ZnO. The Mn is found to carry an average magnetic moment of 0.16 mu(B) per ion. Our ab initio calculations find a valance state of Mn(2+) and that the magnetic moments are ordered ferromagnetically, consistent with the experimental findings. We have obtained room-temperature ferromagnetic ordering in bulk pellets, in transparent films 2-3 microm thick, and in the powder form of the same material. The unique feature of our sample preparation was the low-temperature processing. When standard high-temperature (T > 700 degrees C) methods were used, samples were found to exhibit clustering and were not ferromagnetic at room temperature. This capability to fabricate ferromagnetic Mn-doped ZnO semiconductors promises new spintronic devices as well as magneto-optic components.     

Plant gametogenesis: conservation and contrasts in development

Although the process of gamete formation in plants has many unique features, much has been learnt from the comparative analysis between plants and other eukaryotic systems. Plants have a number of factors that have made them desirable for the analysis of gamete development; these include late germline specification, the non-lethality of mutations affecting gamete development and the large size of their chromosomes. The availability of the fully annotated Arabidopsis genome and comparative analysis using yeast, animal and E. coli has led to the identification and functional characterisation of many genes with roles in gamete development, principally those associated with meiosis, recombination and DNA repair. The advantages that plants give with the use of mutant screens to identify genes associated with gamete formation have also provided access to genes that are difficult to characterise by alternative routes. This has yielded novel information regarding the processes of gamete formation in higher plants. The times may now be changing with the advantages that plants provide serving to advance knowledge of gamete formation in other eukaryotic systems.