Conventional ships are rarely the focus of research projects on autonomous shipping. Nevertheless, the shipping companies are very interested in reducing fuel consumption. This paper proposes a ...gradual approach towards ship automation which starts with the intelligent assistance of common manual steering by means of a Maneuver Assistance System (MAS). The MAS displays a manually improved manoeuvre plan and the future motion based on the current actuator commands. These two assistance functions contribute to a more conscious use of actuators which can significantly reduce power consumption. For further automation, the improved manoeuvre plan is converted into a trajectory by forward simulation, which is then used by a control system. The control system includes feed-forward and feedback control as well as an allocation system based on a simplified dynamic motion model. A cascaded structure is used, where an outer track controller provides velocity and heading commands to an inner velocity and heading controller. The paper presents the necessary framework and the application of this approach to the digitised German research vessel DENEB with the aim to gradually introduce and realise automatic manoeuvring. Results from manual and assisted manoeuvres with the DENEB are analysed and compared. Finally, first results of automatic berthing with the vessel in the port of Rostock are presented.
Abstract
At BESSY II, two new beamlines for RIXS and for X-Ray-microscopy need a short period variably polarizing undulator. For this purpose, the first in-vacuum APPLE II undulator worldwide is ...under construction. The parameters are as follows: period length
λ
0
= 32
mm, # periods
= 78,
minimum gap = 7mm
. The design incorporates a force compensation scheme as proposed by two of the authors at the SRI 2018. All precision parts of the drive chain are located in air. New transverse slides for the transversal slit adjustment have been developed and tested. Optical Micrometers measure the gap and phase positions, similar to the system of the CPMU17 at BESSY II. They provide the signals for motor feedback loops. A new UHV-compatible soldering technique, as developed with industry, relaxes fabrication tolerances of magnets and magnet holders and simplifies the magnet assembly. A 10-period prototype has been setup for lifetime tests of the new magnetic keeper design. The paper summarizes the status of the undulator IVUE32.
For the case of eye tumor therapy with protons, improvements are introduced compared to the standard dose calculation which implies straight-line optics and the constant-density assumption for the ...eye and its surrounding. The progress consists of (i) taking account of the lateral scattering of the protons in tissue by folding the entrance fluence distribution with the pencil beam distribution widening with growing depth in the tissue, (ii) rescaling the spread-out Bragg peak dose distribution in water with the radiological path length calculated voxel by voxel on ray traces through a realistic density matrix for the treatment geometry, yielding a trajectory dependence of the geometrical range. Distributions calculated for some specific situations are compared to measurements and/or standard calculations, and differences to the latter are discussed with respect to the requirements of therapy planning. The most pronounced changes appear for wedges placed in front of the eye, causing additional widening of the lateral falloff. The more accurate prediction of the dose dependence at the field borders is of interest with respect to side effects in the risk organs of the eye.
Stroke imposes a considerable economic burden on the individual and society. Recently, the concept of an integrated stroke unit has been established in several countries to improve the outcome of ...patients. This study evaluates the costs of acute care of the different cerebrovascular insults in a stroke unit.
The study population included 340 patients who were consecutively admitted to the Department of Neurology, Philipps University Marburg, with the diagnosis of stroke or transient ischemic attack (TIA) between January 1 and June 30, 2000. Clinical status and course were evaluated by using the Barthel index and the modified Rankin scale. Employing a “bottom-up” approach, we calculated the costs from the perspective of the hospital and the third-party payer using data from provider departments and other published sources.
Inpatient costs were €3020 (US$3290) for TIA, €3480 (US$3790) for ischemic stroke (IS), and €5080 (US-$5540) for intracerebral hemorrhage (ICH) and differed significantly among these subgroups (
P < .05). Patient subgroups ranked in the same order for average length of stay at 9.4 days for TIA, 10.2 days for IS, and 11.9 days for ICH (
P > .05). Approximately 30% of the hospital costs are due to physician charges and care. Imaging amounted to 10% and lab investigations to 14% of total costs, independent of the diagnosis. Postacute treatment, including inpatient rehabilitation, cost €9880 per patient. Across all diagnostic groups, a mean clinical improvement was observed at time of discharge.
Care of patients with cerebrovascular events in a stroke unit causes a high demand of resources and has a considerable impact on health-care expenditure. Therefore, investigations comparing the stroke unit concept with other strategies in stroke care are necessary to evaluate the stroke unit concept for a rational use of available resources in patients with cerebrovascular events.
WLAN mesh networks are characterized by their flexible and low-cost deployment, scalability, and self-healing capabilities. The new WLAN standard IEEE 802.11s introduces low-level mesh ...interoperability. However, building large-scale real-world test beds and reproducible setups is challenging and costly. In the majority of research works, network simulation is preferred over practical measurements. Here, the main disadvantage exists in simplified device and protocol models restricting the comparability to practical implementations. In contrast, using device emulation still requires the simulation of wireless channel and environment models. Consequently, a combination of both emulation and simulation is needed to enable virtual prototyping of real applications and protocols in WLAN mesh networks. Nevertheless, the computation of complex wireless channel effects requires a decoupling of wall clock and simulation time. Therefore, we present ViPMesh, a virtual prototyping framework for IEEE 802.11s and its Linux reference implementation. ViPMesh relies on WLAN device emulation and nested virtualization using QEMU and Linux containers to support the analysis of real applications on top of an unmodified protocol stack. Adopting an alternative time source approach for QEMU, ViPMesh acts as discrete-event simulator. It further integrates channel and environment models with support for IEEE 802.11n MIMO techniques, high throughput modes, multi-channel operation, and node mobility. To the best of our knowledge, this is the first approach that combines the IEEE 802.11s reference implementation with the described simulation features. The functionality of ViPMesh is demonstrated in different example scenarios.
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