Search

Background Clinical efficacy of pollen allergen immunotherapy has been broadly documented in randomized controlled trials. The underlying clinical endpoints are analysed in seasonal time periods pre-defined on the basis of the background pollen concentration. However, any validated or generally accepted definition from academia or regulatory authorities for this relevant pollen-exposure intensity or period of time (season) is currently not available. Therefore, this Task Force initiative of the European Academy of Allergy and Clinical Immunology (EAACI) aimed to propose definitions based on expert-consensus. Methods A Task Force of the Immunotherapy and Aerobiology and Pollution Interest Groups of the EAACI reviewed the literature on pollen-exposure in the context of defining relevant time intervals for evaluation of efficacy in allergen immunotherapy trials. Underlying principles in measuring pollen exposure and associated methodological problems and limitations were considered in order to achieve a consensus. Results The Task Force achieved a comprehensive position in defining pollen exposure times for different pollen types. Definitions are presented for ‘pollen season’, ‘high pollen season’ (or ‘Peak pollen period’) and ‘high pollen days’. Conclusion This EAACI position paper provides definitions of pollen exposures for different pollen types for use in Allergen Immunotherapy trials. Their validity as standards remains to be tested in future studies. This article is protected by copyright. All rights reserved.

Levosimendan is a calcium sensitizer and ATP-dependent potassium channel opener which exerts sustained hemodynamic, symptomatic and organ-protective effects. It is registered for the treatment of acute heart failure, and when inotropic support is considered appropriate. In the past fifteen years, levosimendan has been widely used in clinical practice, and has also been tested in clinical trials to stabilize at-risk patients undergoing cardiac surgery. Recently, three randomized, placebo-controlled, multicenter studies (LICORN, CHEETAH and LEVO-CTS) have been published reporting on the peri-operative use of levosimendan in patients with compromised cardiac ventricular function. Taken together, many smaller trials conducted in the past suggested beneficial outcomes with levosimendan in peri-operative settings. In contrast, the latest three studies were neutral or inconclusive. In order to understand the reasons for such dissimilarity, a group of experts from Austria, Belgium, Finland, France, Germany, Italy, Switzerland, and Russia, including investigators from the three most recent studies, met to discuss the study results in the light of both the previous literature and current clinical practice. Despite the fact that the null hypothesis could not be ruled out in the recent multicenter trials, we conclude that levosimendan can still be viewed as a safe and effective inodilator in cardiac surgery.This is an open access article distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In the last decade, artificial intelligence and machine learning algorithms have been more and more established for the screening and detection of diseases and pathologies, as well as for describing interactions between measures where classical methods are too complex or fail. The purpose of this paper is to model the measured postoperative position of an intraocular lens implant after cataract surgery, based on preoperatively assessed biometric effect sizes using techniques of machine learning.In this study, we enrolled 249 eyes of patients who underwent elective cataract surgery at Augenklinik Castrop-Rauxel. Eyes were measured preoperatively with the IOLMaster 700 (Carl Zeiss Meditec), as well as preoperatively and postoperatively with the Casia 2 OCT (Tomey). Based on preoperative effect sizes axial length, corneal thickness, internal anterior chamber depth, thickness of the crystalline lens, mean corneal radius and corneal diameter a selection of 17 machine learning algorithms were tested for prediction performance for calculation of internal anterior chamber depth (AQD_post) and axial position of equatorial plane of the lens in the pseudophakic eye (LEQ_post).The 17 machine learning algorithms (out of 4 families) varied in root mean squared/mean absolute prediction error between 0.187/0.139 mm and 0.255/0.204 mm (AQD_post) and 0.183/0.135 mm and 0.253/0.206 mm (LEQ_post), using 5-fold cross validation techniques. The Gaussian Process Regression Model using an exponential kernel showed the best performance in terms of root mean squared error for prediction of AQDpost and LEQpost. If the entire dataset is used (without splitting for training and validation data), comparison of a simple multivariate linear regression model vs. the algorithm with the best performance showed a root mean squared prediction error for AQD_post/LEQ_post with 0.188/0.187 mm vs. the best performance Gaussian Process Regression Model with 0.166/0.159 mm.In this paper we wanted to show the principles of supervised machine learning applied to prediction of the measured physical postoperative axial position of the intraocular lenses. Based on our limited data pool and the algorithms used in our setting, the benefit of machine learning algorithms seems to be limited compared to a standard multivariate regression model.In den vergangenen Jahren wurden zunehmend Systeme der künstlichen Intelligenz in der Medizin etabliert, die Pathologien oder Erkrankungen erkennen und schwer zu erfassende Zusammenhänge zwischen Eingangsgrößen beschreiben sollen. Ziel der Studie ist es, anhand von biometrischen Messgrößen vor der Kataraktoperation die physikalische Position der Intraokularlinse nach der Operation mit Verfahren des maschinellen Lernens vorherzusagen.249 Augen von Patienten, die sich zur elektiven Kataraktoperation an der Augenklinik Castrop-Rauxel vorstellten, wurden mit dem IOLMaster 700 (Carl Zeiss Meditec) und vor sowie nach der Operation mit dem Casia 2 (Tomey) untersucht. Aus den Effektgrößen Augenlänge, Hornhautdicke, interne Vorderkammertiefe, Linsendicke, mittlerer Hornhautradius und Hornhautdurchmesser wurde eine Auswahl von 17 Algorithmen des Maschinenlernens auf ihre Vorhersagequalität hin getestet für die Bestimmung der postoperativen internen Vorderkammertiefe (AQD_post) und der Lage des Linsenäquators relativ zum Hornhautscheitel (LEQ_post).Die 17 Modelle (4 Algorithmusfamilien) variierten im mittleren quadratischen/mittleren absoluten Vorhersagefehler zwischen 0,187/0,139 mm und 0,255/0,204 mm (AQD_post) und 0,183/0,135 mm und 0,253/0,206 mm (LEQ_post) bei einer Kreuzvalidierung (5-fold cross validation). Der Algorithmus mit der besten Performance war bei beiden Vorhersagen ein Gaussian Process Regression Model mit einem exponentiellen Kernel. Prüft man am gesamten Datensatz (ohne Aufteilung in Trainings- und Validierungsdaten) ein einfaches multiples lineares Regressionsmodell gegen den Algorithmus mit der besten Performance, so ergibt sich bei der Vorhersage von AQD_post/LEQ_post ein mittlerer quadratischer Vorhersagefehler von 0,188/0,187 mm gegenüber dem Gaussian Process Regression Model mit 0,166/0,159 mm.In der Arbeit soll das Prinzip des überwachten Maschinenlernens in der Anwendung auf die Nachbildung der physikalisch gemessenen postoperativen axialen Position von Intraokularlinsen gezeigt werden. Bei den vorliegenden Daten ist der Gewinn durch die Verwendung von Algorithmen des maschinellen Lernens (bei den hier verwendeten Algorithmen) gegenüber einem multiplen linearen Regressionsansatz gering.

This paper provides a detailed system theoretical model of a plenoptic camera with the aim to provide in-depth understanding of the plenoptic data recording concept and its effects. Plenoptic cameras, also known as light field cameras, were firstly thought of in the beginning of the 20th century and became recently possible thanks to rapid development of processing hardware and the increase of camera sensor resolution. Despite being a new type of sensor, they are operated in the same way as conventional cameras, but offer several advantages. A plenoptic camera consists of a main lens and a lenslet array (microlens array) right in front of the detector. The microlens array causes not only the recording of the incident location of a light ray on the sensor, as it is done by a conventional camera, but also the incident direction. Such a record can be represented by a 4-D data set known as the light field. In fact, by inserting a microlens array any conventional camera can be transformed into a plenoptic camera. The plenoptic recording concept and the 4-D light field provide multiple advantages over conventional cameras. For example, a single recorded light field allows first, to reconstruct novel views with small changes in viewpoint, second, to create a depth map, and third, to refocus images after the data capture. Hence, the process of focusing is shifted from hardware to software. Last, but not least, plenoptic cameras allow an extended depth of field in comparison to a conventional camera and the use of a bigger camera aperture. Most of the mentioned advantages become particularly effective at close-range to an object. The German Aerospace Center performs research on plenoptic cameras for close-range imaging in space. Possible applications are for example robot vision with plenoptic cameras for robotic arm operations during on-orbit servicing missions or the use of plenoptic cameras on rovers in the course of exploration missions to other planets. Those application scenarios and the demanding conditions in space require thorough comprehension of plenoptic cameras. For this purpose, this paper shall provide a detailed model of plenoptic cameras, which allows to derive camera parameters and optimize them with particular attention to the user requirements and to generate synthetic data. The latter can be utilized to assess the evaluation algorithms, which are not mentioned in detail in this paper. The modeling of the plenoptic camera is mainly based on the theory of geometric optics expanded by elements of diffraction optics.

The subject of this paper is a fragmented oil-lamp, discovered at Pontes (east Serbia) dated to the 6th century, whose handle ending is shaped as a woman’s head. The question posed in this paper is whether the image of this woman could be identified as a portrait of some particular person or if it is just as a pictorial sign with some complicated symbolic meaning. The suggested identification alludes to the image of some of the empresses from the second half of the 6th century. [Projekat Ministarstva nauke Republike Srbije, br. 177007: Romanisation, urbanisation and transformation of urban centres of civil, military and residential character in Roman provinces in the territory of Serbia i br. 47018: Viminacium, Roman city and military camp - research of the material and non material culture of inhabitants by using the modern technologies of remote detection, geophysics, GIS, digitalization and3D visualization]

The paper deals with the role of the Kaitseliit (Defence League) voluntary defence organisationin Estonia’s defence in the years of the Estonian War of Independence (also known as theLiberation War) and in peacetime until 1940, with attention focused mainly on the 1930s. Anoverview is provided of the historiography, the formation of Kaitseliit in 1918, its role in theLiberation War, the period of decreasing activity of the organisation after the war, and the restorationand development of Kaitseliit in the 1920s and 1930s. The author reviews the objectivesof the organisation, issues of its membership, structure, management and armament,as well as the use of Kaitseliit and its units in Estonian military defence and internal training.The paper also attempts to answer the question how the role of Kaitseliit in Estonian nationaldefence developed. Key words: paramilitarism, Kaitseliit, paramilitary organisational structure, military defenceof Estonia, military training. DOI: http://dx.doi.org/ 10.15181/ahuk.v28i0.928

This paper deals with a low to middle order finite volume/lumped capacitance thermal model of an electric machine and the correction of critical parameters. The different parts of the electric machine are divided into sub-volumes called finite volumes or lumped capacitances. From the given characteristic geometry of the electric machine, the thermal resistances to create the system matrix are calculated. The resulting non-linear equation system is solved for steady state condition for a given current density. The result is compared to experimental measurements allowing the calculation of material correction parameters included in the thermal resistances using the least square method. In a second step an experiment with time dependent current in the stator windings is done. The experiment then is simulated with the time dependent current measured in the experiment using the correction parameters found in the first step. The paper aims to present the possibility to calculate the maximum temperatures very accurately with this method.

In this paper we present our multicopter flight assistance software uavRC, which bears on a distributed system with interchangeable MAV-drivers and a browser-based user interface that can be used on any computer, tablet or smartphone. The software components can be distributed on different computers and are even executable on a Raspberry Pi. The components communicate over a well-defined interface. One module is the browser based user interface, another module is the MAV driver. There are additional modules like a task-scheduler, a path-planer and many more. Currently the software is in beta stage, so there is still a lot of work in progress. With this paper we focus on the software architecture.

In this paper, we report on the first steps in an empirical investigation into the nature of the laser survivability curve. The laser survivability curve is the onset threshold as a function of shot number. This empirical investigation is motivated by the desire to design a universal procedure for the measurement of the so-called S on 1 damage threshold. Analysis is carried on the test results for first results from a large set of planned measurements from identical samples produced for this investigation. The sample set and test conditions are discussed. A pair of measurements, one taken at atmospheric pressure and one at vacuum are introduced and analyzed as an example. Interim observations on the nature of the laser survivability curve, and its determination to be used in the remainder of this investigation based on this initial look, are presented at the conclusion of this paper.

A Synthetic Aperture Radar (SAR) system measures among other quantities the terrain radar reflectivity. After image calibration, the pixel intensities are commonly expressed in terms of radar cross sections (for point targets) or as backscatter coefficients (for distributed targets), which are directly related. This paper argues that pixel intensities are not generally proportional to radar cross section or derived physical quantities. The paper further proposes to replace the inaccurate term radar cross section by equivalent radar cross section as the radiometric measurement quantity for SAR images. The measurement procedure as such remains unchanged. Two problems are seen with using radar cross section as the radiometric measurement quantity for point targets. First, the radar cross section is frequency and/or angular dependent for many targets, whereas a SAR system operates not at a single set but through a range of frequencies and aspect angles. This begs the question of which radar cross section within this two-dimensional range should actually be taken as the measurement result. Second, the pixel intensities seen in SAR images are the output of a filtering process, which is affected by the complex transfer function of the point target. Radar cross section, on the other hand, does not depend on phase. The equivalent radar cross section expresses the reflectivity in terms of the radar cross section of an equivalent conducting sphere which would result in the same pixel intensity as the one observed if the sphere were to replace the actual target in the scene. This distinction is crucial in defining the measurand for radiometric SAR measurements in principal, and hence it is important for radiometric SAR calibration. It is furthermore of particular practical importance for current and emerging wideband, high-resolution, and high-accuracy SAR systems.

This paper discusses the remote control as an every-day, and yet frequently overlooked technology. The remote control and the resulting possibility of zapping may be seen as a widespread and consequential cultural technology which decisively influences viewers’ behavior and action. In accordance, this paper will aim to demonstrate the socio-logic of the remote control. Initially, it will show what controversial image of the zapping recipient exists in the academic Literature: he is partly demonized, partly idealized. Furthermore, it will allow insight into the sometimes awkward methods employed in analyzing zapping. Subsequently the paper will show: remote controls have special button configurations which crucially affect the order in which the various channels are viewed; they lead to specific signatures of channel-changing. The paper closes with considerations on whether the remote control may count as an obsolete technology and the zapping TV-viewer as a species facing extinction.

Conventional CMOS image sensors with a linear transfer characteristic only have a limited dynamic range (DR) of about 60–70 dB. To extend the dynamic range considerably, the already successfully demonstrated concept of a linear self-reset pixel was employed in this work. With the self-reset concept the limit of the maximum analyzable photo generated charge (Qmax⁡) during the exposure time is extended to a multiple of the saturation charge of the photo diode (Qsat) by asynchronous self-resets of the photo diode. Additionally, the remaining charge at the end of the exposure time is evaluated to increase the resolution of the opto-electronic conversion. Thus we achieved pixels with a DR of more than 120 dB combined with an improved low light sensitivity using a pinned photodiode. This paper focuses on two topics: One is the realization and opto-electronic characterization of further self-reset pixel cells for an experimental optimization of the functionality with respect to linearity and high signal-to-noise ratio. The second one is the assembly and digital readout of a cluster structure composed of 16 × 16 pixel matrix on a CMOS test chip. One constraint for later usage of the pixel cells in a high resolution (> VGA) image sensor is the required layout area of the individual circuit blocks. For the cluster structure a size of 20 × 20 µm2 for the analog part of the pixel containing the photo diode and the other analog circuit blocks, the comparator and the signal shaping, was desired. The circuit design and layout work included several variants of the pinned photo diode with floating diffusion (FD) readout node, which is also used for analog voltage storage, and different control transistors. Further for the comparator a telescopic differential amplifier with high gain was implemented as well as peripheral 10 bit counter/shift register as static and dynamic versions. Test chips have been fabricated in an advanced 0.18 µm CMOS technology for optical sensors with low leakage currents. The sensor chips have been evaluated with a specifically developed test setup which gives the flexibility to arbitrarily generate the digital and analog control signals in terms of timing and voltage levels. Based on this, the number of asynchronous self-resets could be read out from the counters of the pixel cells as coarse values. The remaining charge at the end of the integration time was digitized using a ramp analog to digital conversion and could be read out as fine values. An opto-electronic characterization with adjustable illumination from 0 lx to 13 klx was done to measure and analyze the opto-electronic conversion function (OECF) and the noise of six different self-reset pixel cells having the high-gain differential amplifier as comparator. Finally the coarse values of two implemented 16 × 16 pixel clusters could be read out as a mini camera using a lens for optical image formation.

This paper introduces a framework for managing bias in machine learning (ML) projects. When ML-capabilities are used for decision making, they frequently affect the lives of many people. However, bias can lead to low model performance and misguided business decisions, resulting in fatal financial, social, and reputational impacts. This framework provides an overview of potential biases and corresponding mitigation methods for each phase of the well-established process model CRISP-DM. Eight distinct types of biases and 25 mitigation methods were identified through a literature review and allocated to six phases of the reference model in a synthesized way. Furthermore, some biases are mitigated in different phases as they occur. Our framework helps to create clarity in these multiple relationships, thus assisting project managers in avoiding biased ML-outcomes.

This year's gathering in Durham marks 21 years of meetings of European quantitative geographers. The paper, originally presented at the 1999 Durham meeting, provides a review of what has been achieved. Initially the circumstances leading to the first meeting in Strasbourg (1978) are outlined. The subsequent ten meetings have seen a general, if not consistent, increase in the number of delegates and an increase in the number of nationalities represented. The papers have reflected larger changes in our discipline. Initially, work concentrated on statistical analysis of spatial data, but the 1980s saw an extension into formal mathematical modeling and what is nowadays sometimes called geographic information science. Despite, or perhaps because of, the group never having had any subsidy from EU, there have been a number of published outputs, not least of which have been research collaborations, a journal, several edited books, and inputs into other European initiatives such as the GISDATA programme. It is concluded that these gatherings can look forward to the future with confidence.

With increasing radar activities in the automotive, industrial and private sector, there is a need to test radar sensors in their environment. A radar target simulator can help testing radar systems repeatably. In this paper, the authors present a concept of low-cost hardware for radar target simulation. The theoretical foundations are derived and analyzed. An implementation of a demonstrator operating in the 24 GHz ISM band is shown for which the dynamical range simulation was implemented in a FPGA with fast sampling ADCs and DACs. By using a FIR filtering approach a fine discretization of the range could be reached which will furthermore allow an inherent and automatic Doppler simulation by moving the target.

In the era of the sustainable development goals (SDGs) and calls for climate action, business is challenged to respond more effectively to societal and environmental challenges. Collaboration with stakeholders requires an ability for broader collaboration competencies. These form a part of an established literature on responsible leadership (RL) competencies. Human resources managers, consultants and educators in charge of developing such competencies demand clarity on the definition and a practical measurement tool for RL. This paper addresses both by proposing a RL definition and a RL competency model, that has been operationalized into a free online tool for individuals and groups. This free Competency Assessment for Responsible Leadership (CARL) tool is used to assess stakeholder engagement, individual and group leadership development, and internal sustainable development transformation work. The CARL online tool serves to systematically analyze and develop RL competencies, both in business and educational practices, and helps advance the RL theory based on insights from practice.

During the increasing dissemination of renewable energy sources the potential and actual interference effects of wind turbine plants became obvious. Turbines reflect the signals of weather radar and other radar systems. In addition to the static radar echoes, in particular the Doppler echoes are to be mentioned as an undesirable impairment Keränen (2014). As a result, building permit is refused for numerous new wind turbines, as the potential interference can not be reliably predicted. As a contribution to the improvement of this predictability, measurements are planned which aim at the high-frequency characterisation of wind energy installations. In this paper, a cost-effective FMCW radar is presented, which is operated in the same frequency band (C-band) as the weather radars of the German weather service. Here, the focus is on the description of the hardware design including the considerations used for its dimensioning.

In situ measurements of cloud droplet number concentration N are limited by the sampled cloud volume. Satellite retrievals of N suffer from inherent uncertainties, spatial averaging, and retrieval problems arising from the commonly assumed strictly adiabatic vertical profiles of cloud properties. To improve retrievals of N it is suggested in this paper to use a synergetic combination of passive and active airborne remote sensing measurement, to reduce the uncertainty of N retrievals, and to bridge the gap between in situ cloud sampling and global averaging. For this purpose, spectral solar radiation measurements above shallow trade wind cumulus were combined with passive microwave and active radar and lidar observations carried out during the second Next Generation Remote Sensing for Validation Studies (NARVAL-II) campaign with the High Altitude and Long Range Research Aircraft (HALO) in August 2016. The common technique to retrieve N is refined by including combined measurements and retrievals of cloud optical thickness τ, liquid water path (LWP), cloud droplet effective radius reff, and cloud base and top altitude. Three approaches are tested and applied to synthetic measurements and two cloud scenarios observed during NARVAL-II. Using the new combined retrieval technique, errors in N due to the adiabatic assumption have been reduced significantly.

Despite treatment options of cancer patients have been improved, the treatment of complications is usually very complex and often includes intensive care unit admission. Infections play a major role here. Risk patients and factors, timely detection of infections and septic states, diagnostic options and treatment options in the management of these cancer patients will be presented in this paper.

Summary Moulded Case Circuit Breaker (MCCB) is a protective device used for low voltage protection in the range of 12–1250 A. It is having fast breaking and making ability due to special contact structure. In case of transformer it is generally placed in secondary side and in case of motor protection it is used as backup protection. The existing design is suffering from chattering of contact tip which lead to erosion and in turn affect electrical life. It also reduces interrupting/breaking capacity of MCCB. In this paper, detailed study of the factors and constraints related to repulsion threshold current ( I rp ) and consistency of magnetic release for 630 A MCCB is carried out using Finite Element tool JMAG to find out limitations and scope of design improvements in existing design. The proposed suggestion is validated by testing.

Summary Cryptographic techniques are employed for minimizing security hazards to sensitive information. To make the systems more robust, cyphers or crypts being used need to be analysed for which cryptanalysts require ways to automate the process, so that cryptographic systems can be tested more efficiently. Evolutionary algorithms provide one such resort as these are capable of searching global optimal solution very quickly. Cuckoo Search (CS) Algorithm has been used effectively in cryptanalysis of conventional systems like Vigenere and Transposition cyphers. Linear Feedback Shift Register (LFSR) is a crypto primitive used extensively in design of cryptosystems. In this paper, we analyse LFSR based cryptosystem using Cuckoo Search to find correct initial states of used LFSR. Primitive polynomials of degree 11, 13, 17 and 19 are considered to analyse text crypts of length 200, 300 and 400 characters. Optimal solutions were obtained for the following CS parameters: Levy distribution parameter ( β ) = 1.5 and Alien eggs discovering probability ( p a ) = 0.25.

A small-scale hybrid power plant with CSP and biogas boiler was built at the University ENIT as a laboratory for research and education. The CSP system consists of parabolic trough collectors operating in direct steam generation (DSG) concept. An ORC turbine with a newly developed generator design generates up to 65 kW electrical from low temperature steam. Additionally, biomass anaerobic digestion and phase change storage are demonstrated. While the commissioning of the plant is scheduled for the end of August 2017, commissioning of the single components has already been successfully completed. Highlights and main results from installation and commissioning period are published within this paper.

This paper presents a numerical comparison of charge pumps (CP) designed for a high linearity and a low noise to be used in a fractional-N phase-locked loop (PLL). We consider a PLL architecture, where two parallel CPs with DC offset are used. The CP for VCO fine tuning is biased at the output to keep the VCO gain constant. For this specific architecture, only one transistor per CP is relevant for phase detector linearity. This can be an nMOSFET, a pMOSFET or a SiGe HBT, depending on the design. The HBT-based CP shows the highest linearity, whereas all charge pumps show similar device noise. An internal supply regulator with low intrinsic device noise is included in the design optimization.

Ultra-wideband (UWB) is a promising technology for positioning systems that has undergone massive research development in recent years. Most UWB positioning systems assume prior knowledge on the positions of the UWB anchors. Without knowing the UWB anchor positions, an accurate position estimate of an UWB tag is difficult. Hence, this paper presents a novel cooperative pedestrian simultaneous localization and mapping (SLAM) algorithm using an UWB positioning system without the necessity to have the prior information on the UWB anchor positions. To obtain accurate estimates of the UWB anchor positions, the estimations of the UWB anchor positions are shared between different mobile units. An increased accuracy of the estimated UWB anchor position relates directly to a more accurate position estimate of the mobile unit position. We evaluate the proposed algorithm based on measurements with multiple mobile units and fixed anchors with unknown positions. The evaluations show that an accurate position estimation of both the mobile units and the anchors is possible without any prior knowledge on the UWB anchor positions.

A traffic data collection system using wireless radio frequency (RF) technologies, e.g. Bluetooth or Wi-Fi, allows for area wide measurement of traffic. This includes travel times on the whole road network. This paper aims to present the technical overview of a newly developed ITS system called DYNAMIC. This system supports indirect data acquisition by moving detectors, processing and provision of floating observer information on the basis of mobile wireless RF data. DYNAMIC consists of sensor hardware and software components like data collection, data import, transport mode detection, data processing, data fusion and visualization.

On the basis of documents in the Latvian State Archives, this paper discusses the armed struggleagainst the Soviet authorities in Vidzeme, in northern Latgala, and Sela, which took placeduring the Latvian Wars of Independence, and was joined voluntarily by the local populationin an organised way. The discussion tells about the armed guerrilla groups that operated inVidzeme and northern Latgala in 1919, and formed a serious obstacle to the establishmentof Soviet power, the participation of ethnic minorities in guerrilla groups, and the features ofthe guerrilla fighting. The collaboration between Latvian guerrillas and Lithuanian troops, andtheir role in the expulsion of Soviet Latvian troops from the country, is analysed. Key words : paramilitarism, guerrilla struggle, Latvian Army, Latvian Wars of Independence. DOI: http://dx.doi.org/ 10.15181/ahuk.v28i0.922

This paper introduces a method for dead time optimization in variable speed motor drive systems. The aim of this method is to reduce the conduction time of the freewheeling diode to a minimum without generation of cross conduction. This results in lower losses, improved EMC, and less overshooting of the phase voltage. The principle of the method is to detect beginning cross currents without adding additional components in the half bridge like resistors or inductances. Only the wave shape of the phase voltage needs to be monitored during switching. This is illustrated by an application of the method to a real power converter.

Single-laser-shot temperature measurements at 5 kHz were performed in a gas turbine model combustor using femtosecond (fs) coherent anti-Stokes Raman scattering (CARS). The combustor was operated at two conditions; one exhibiting a low level of thermoacoustic instability and the other a high level of instability. Measurements were performed at 73 locations within each flame in order to resolve the spatial flame structure and compare to previously published studies. The measurement procedures, including the procedure for calibrating the laser system parameters, are discussed in detail. Despite the high turbulence levels in the combustor, signals were obtained on virtually every laser shot, and these signals were strong enough for spectral fitting analysis for determination of flames temperatures. The spatial resolution of the single-laser shot temperature measurements was approximately 600 µm, the precision was approximately ±2%, and the estimated accuracy was approximately ±3%. The dynamic range was sufficient for temperature measurements ranging from 300 K to 2200 K, although some detector saturation was observed for low temperature spectra. These results demonstrate the usefulness of fs-CARS for the investigation of highly turbulent combustion phenomena. In a companion paper, the time-resolved fs CARS data are analyzed to provide insight into the temporal dynamics of the gas turbine model combustor flow field.

This paper presents monostatic radar cross section (RCS) measurements of a human hand in the frequency range from 60GHz to 90 GHz. These values are important parameters for system designs in the emerging field of radar-based gesture recognition. The measurement procedure is described in detail and results of four gestures at three different distances are depicted and analysed., acceptedVersion

The fuel consumption of future civil aircraft needs to be reduced because of the CO2 restrictions declared by the European Union. A consequent lightweight design and a new engine concept called counter-rotating open rotor are seen as key technologies in the attempt to reach this ambitious goals. Bearing in mind that counter-rotating open rotor engines emit very high sound pressures at low frequencies and that lightweight structures have a poor transmission loss in the lower frequency range, these key technologies raise new questions in regard to acoustic passenger comfort. One of the promising solutions for the reduction of sound pressure levels inside the aircraft cabin are active sound and vibration systems. So far, active concepts have rarely been investigated for a counter-rotating open rotor pressure excitation on complex airframe structures. Hence, the state of the art is augmented by the preliminary study presented in this paper. The study shows how an active vibration control system can influence the sound transmission of counter-rotating open rotor noise through a complex airframe structure into the cabin. Furthermore, open questions on the way towards the realisation of an active control system are addressed. In this phase, an active feedforward control system is investigated in a fully equipped Dornier 728 experimental prototype aircraft. In particular, the sound transmission through the airframe, the coupling of classical actuators (inertial and piezoelectric patch actuators) into the structure and the performance of the active vibration control system with different error sensors are investigated. It can be shown that the active control system achieves a reduction up to 5 dB at several counter-rotating open rotor frequencies but also that a better performance could be achieved through further optimisations.

In the current paper psychophysical aspects of a vibrotactile feedback device were investigated and its potential of signal modulation was analyzed. We identified magnitude calibration factors for equal perceptions of the different stimulation locations of the device and determined the spatial acuity with which the user is able to correctly detect the stimulation’s location. Furthermore we investigated different approaches of vibrotactile stimulation for communicating direction and distance information to the human arm (motion guidance) and also explored different approaches of signal modulation for the transmission of additional information content.

Radio-frequency (RF) scattering parameters (S-parameters) play an important role to characterise RF signal transmission and reflection of active and passive devices such as transmission lines, components, and small-signal amplifiers. Vector network analysers (VNAs) are employed as instrumentation for such measurements. During the last years, the upper frequency limit of this instrumentation has been extended up to several hundreds of GHz for waveguide measurements. Calibration and verification procedures are obligatory prior to the VNA measurement to achieve accurate results and/or to obtain traceability to the International System of Units (SI). Usually, verification is performed by measuring well-matched devices with known S-parameters such as attenuators or short precision waveguide sections (shims). In waveguides, especially above 110 GHz, such devices may not exist and/or are not traceably calibrated. In some cases, e.g. filter networks, the devices under test (DUT) are partly highly reflective. This paper describes the dependency of the S-parameters a) on the calibration procedure, b) on the applied torque to the flange screws during the mating process of the single waveguide elements. It describes further c) how highly-reflective devices (HRD) can be used to verify a calibrated VNA, and d) how a measured attenuation at several hundreds of GHz can be substituted by a well-known coaxial attenuation at 279 MHz, the intermediate frequency (IF) of the VNA, to verify the linearity. This work is a contribution towards traceability and to obtain knowledge about the measurement uncertainty of VNA instrumentation in the millimetre-wave range.

Field robots - robots used in unstructured and dynamic environments - and teleoperation have shifted into the focus of a variety of industrial branches in the past few years. The lack of space in the atomic industry, on oil platforms and in space applications demands additional adaptations to current robotic setups. In this paper a MMSS (Multi-Master-Single-Slave) haptic teleoperation system is proposed through which one operator using two master arms can manipulate objects in a cooperative way via one slave robot and a virtual gripping point. To ease the execution of a peg-in-hole task of big objects, a task allocation in the cartesian frame of the virtual gripping point is introduced additionally. The stability of this multilateral system with time delay is guaranteed by the Time Domain Passivity Approach. Therefore the system is divided into several modular subsystems which renders the system easily adaptable to other scenarios.

Since the first communications satellites have been launched to space with the beginning of the 1960s, these systems have undergone a rapid development. Amongst others, this development is driven by an increasing number of subscribers exchanging larger and larger data volumes. This need of data capacity cannot be satisfied alone by raising the sheer number of communications satellites, but requires powerful individual systems, which operate reliably and are cost effective at the same time. In this context two requirements on the communications antenna are the provision of high directional gain and robustness in terms of beam stability. Classically, large unfurlable mesh reflector antennas in conjunction with feed arrays are adopted to illuminate a certain region on ground with high gain. An inherent problem of such reflector-feed configurations is that these systems are prone to feed element failures. In the worst case, this could result in a ‘blind’ spot, where no communication is possible. This paper introduces a robust antenna concept, which combines the virtue of reflector antennas, namely the large aperture, with the advantage of direct radiating planar array antennas, which is the beam stability in the presence of element failures. In order to unfold its full potential this concept makes use of digital beamforming techniques, which allow to control the illumination in a flexible way.

In this paper we present our work on enabling Balloon launched high altitude UAV Missions for an autopilot system previously used only at lower levels in visual line of sight conditions. One field of our research in the context of flying robotics is focused on high altitude pseudo satellites (HAPS). To gain operational experience in high altitude flying and for system and payload testing, a balloon launched small UAV (sub 10kg) system was designed including building an optimized airframe. Balloon launching was chosen because it offers fast and clearly regulated access to the desired altitudes. Our autopilot system has proven its capabilities in many years of flight experiments with different platforms (helicopter and fixed wing). The main characteristics are modularity and easy use for scientists. On the hardware level the task was to integrate the existing segmented systems of the research autopilot in a compact form factor, with the possible use in larger platforms in mind. The design was driven by the special thermal requirements resulting from flying in stratospheric conditions. In the autopilot software, several mission specific functions had to be added, which only required moderate effort due to the modular system design. Major changes included adding a flight termination manager. A launch routine was developed allowing a safe transition from free-fall to stable horizontal flight in thin air after being dropped from the balloon. Extensive testing was performed to validate the design. Simulating the mission, including balloon ascend, was used to check the mission software. Thermal and pressure conditions at altitude were replicated in a thermal vacuum chamber with additional sensors applied to identify problems. The simulation and control laws were verified by means of low altitude test flights.

Increasing resolution and accuracy is an important issue in almost any type of radar sensor application. However, both resolution and accuracy are strongly related to the available signal bandwidth and energy that can be used. Nowadays, often several sensors operating in different frequency bands become available on a sensor platform. It is an attractive goal to use the potential of advanced signal modelling and optimization procedures by making proper use of information stemming from different frequency bands at the RF signal level. An important prerequisite for optimal use of signal energy is coherence between all contributing sensors. Coherent multi-sensor platforms are greatly expensive and are thus not available in general. This paper presents an approach for accurately estimating object radar responses using subband measurements at different RF frequencies. An exponential model approach allows to compensate for the lack of mutual coherence between independently operating sensors. Mutual coherence is recovered from the a-priori information that both sensors have common scattering centers in view. Minimizing the total squared deviation between measured data and a full-range exponential signal model leads to more accurate pole angles and pole magnitudes compared to single-band optimization. The model parameters (range and magnitude of point scatterers) after this full-range optimization process are also more accurate than the parameters obtained from a commonly used super-resolution procedure (root-MUSIC) applied to the non-coherent subband data.

In rehabilitation robotics it is highly desirable to find novel human-machine interfaces for the disabled, in particular to substitute or augment surface electromyography (sEMG), trying to keep at the same time its easiness of use, precision and non-invasiveness. In this paper we design and demonstrate one such device, based upon Force-Sensing Resistors (FSRs). An array of 10 FSRs was wrapped around the proximal section of the forearm of ten intact subjects engaged in pressing on an accurate force sensor with their fingers (this includes the rotation of the thumb). The FSRs would detect the forearm surface deformations induced by muscle activity; the signals provided by the FSRs were then matched to the recorded forces. The experimental results show that finger forces can be predicted using this device with the same accuracy obtained in literature using sEMG. The device, even as an academic prototype, weighs about 65 grams and costs around 50 EUR. Thus, it is remarkably light and cheap in comparison to standard sEMG electrode arrays.

Electric vehicle power train concepts with wheel-hub or close-to-wheel propulsion open up a whole new area of vehicle control possibilities. The DLR robotic concept vehicle ROMO allows the evaluation of these possibilities using integrated chassis control. With its electric drive train it is possible to recuperate kinetic energy during braking process. Using only the electric motors for braking, an increased mass of electric drives & energy storage would be necessary in order to comply to legal passenger vehicle braking regulations. Therefore, the combination of friction based brake and electric motor brake can be advantageous. In this paper, object oriented models (Modelica) of a permanent magnet synchronous machine driven electro-hydraulic disc brake and an in-wheel direct driven traction motor are presented. Furthermore, two torque blending algorithms of an electro-hydraulic disc brake and an in-wheel permanent magnet synchronous machine are evaluated. One algorithm is based on a dynamic control allocation using real-time capable quadratic programming, the other is a feed forward control based on heuristic considerations. Finally, four comparison methods are presented and applied to evaluate the performance of the used torque blending.

Future high speed trains are the main focus of the DLR research project Next Generation Train (NGT). One central point of the research activities is the development of a mechatronic track guidance for the two axle intermediate wagons with steerable, individually powered, independently rotating wheels. The traction motors hereby fulfil two functions; they concurrently are traction drives and steering actuators. In this paper, the influence of the track properties – line layout and track irregularities – on the performance requirements for the guidance actuator is investigated using multi-body-models in SIMPACK®. In order to compromise on the design conflict between low wheel wear and low steering torques, the control parameters of the mechatronic track guidance are optimized using the DLR in-house software MOPS. Besides of the track irregularities especially the increasing inclination at transition curves defines high actuator requirements due to gyroscopic effects at high speed. After introducing a limiter for the actuating variables into the control system a good performance is achieved.

Endwall losses and secondary air flow are considered to be responsible for a significant part of the flow losses in compressors. Their reduction can be achieved by 3D blade design and non-axisymmetric endwalls. In order to evaluate the potential of both effects, an analysis of secondary air flow and the origin of losses is realized. This paper presents multiple numerical simulations to determine the predominant phenomena at the origin of losses in the hub region of the last rotor of the Rig 250, a 4-stage compressor with cantilevered stators and rotor tip clearances. In a first study (I), an inviscid endwall condition at the hub of rotor 4 has been investigated. This condition strongly reduces the secondary air flow from the pressure side to the suction side and shows a significant reduction of the losses in the hub region. But the typical loss distribution over the blade height with a local maximum between 5 and 15 % of the blade height is not changed. Through this study the losses generated by the endwall boundary layer and the resulting secondary air flow are evaluated. Moreover, the potential for endwall contouring and 3D blading in the hub region is estimated, which can be used in future design studies. In the second study (II), ideal radial distributions of the velocity and of the inflow angles at the inlet of the rotor 4 are set. The results show the dependencies between the inflow condition and the loss production in the blade passage near the endwall. These studies sets the theoretical maximal potential for improvement techniques, like endwall contouring or the modification of the upstream stator.

An ESD failure occurring inside the core circuitry known as “inverter failure" will be presented and analysed in this paper. The compact model utilised for this investigation is shortly presented. It will be shown that not only properties of the failed structure are relevant, but also surrounding circuitry. So the gate of an inverter will be connected during the simulations in diverse ways to VDD and VSS. The different possibilities of influence of pre drivers can be appraised in this way. In order to achieve a detailed understanding of the individual failure, it is necessary to include ambient circuitry as well as parasitics like resistors and capacitances.

PurposeThe purpose of this paper is to show the performance during flight tests of the proposed GBAS Approach Service Type D navigation – intended to support autoland operations – in comparison to ILS.Design/methodology/approachAn experimental GBAS station was installed at the research airport in Braunschweig. Data processing complied with the currently proposed requirements to support automatic landings. Corrections for GPS measurements and integrity parameters were sent to a research aircraft which was equipped with an experimental GPS receiver providing raw measurement data. The received data and measurements were then processed on board in real‐time and provide approach guidance information to the experimental pilot in form of a flight director indication. To evaluate system performance the authors create a truth reference track from a post processed carrier phase solution. Finally, the GBAS outputs and the received ILS signals are compared to the truth reference.FindingsThe system performed well within all specifications and showed full availability at all times during the flight. Compared to ILS, GBAS is significantly more precise and shows almost no noise.Research limitations/implicationsThe navigation solution was flown manually according to flight director displays, therefore no automatic approaches and landings could be performed.Practical implicationsIt has been demonstrated that GBAS can support the intended operations under nominal conditions.Originality/valueThis work is part of the ongoing validation of the proposed standards for a satellite based landing system. It compares GBAS and ILS data from flight tests carried out with a representative aircraft.

Summary Between the years 1944 and 1954, the German Egyptological journal Zeitschrift für Ägyptische Sprache und Altertumskunde (ZÄS) stopped publication due to the Second World War and its repercussions. This paper presents a document written by Hermann Grapow in 1947 intended to help the publishing house J. C. Hinrichs obtain a licence from the authorities in the Soviet Occupation Zone, in order to publish the ZÄS anew. Here, emphasis will be placed upon the way in which Hermann Grapow argues in favour of the grant of the licence in his petition.

Existing solar thermal power plants are based on steam turbine cycles. While their process temperature is limited, solar gas turbine (GT) systems provide the opportunity to utilize solar heat at a much higher temperature. Therefore there is potential to improve the efficiency of future solar thermal power plants. Solar based heat input to substitute fuel requires specific GT features. Currently the portfolio of available GTs with these features is restricted. Only small capacity research plants are in service or in planning. Process layout and technology studies for high solar share GT systems have been carried out and have already been reported by the authors. While these investigations are based on a commercial 10MW class GT, this paper addresses the parameterization of high solar share GT systems and is not restricted to any type of commercial GT. Three configurations of solar hybrid GT cycles are analyzed. Besides recuperated and simple GT with bottoming Organic Rankine Cycle (ORC), a conventional combined cycle is considered. The study addresses the GT parameterization. Therefore parametric process models are used for simulation. Maximum electrical efficiency and associated optimum compressor pressure ratio πC are derived at design conditions. The pressure losses of the additional solar components of solar hybrid GTs have a different adversely effect on the investigated systems. Further aspects like high ambient temperature, availability of water and influence of compressor pressure level on component design are discussed as well. The present study is part of the R&D project Hybrid High Solar Share Gas Turbine Systems (HYGATE) which is funded by the German Ministry for the Environment, Nature and Nuclear Safety and the Ministry of Economics and Technology.

Despite of a lot of efforts to develop a good de-speckling method for radar/SAR imagery (see e.g. [1, 2]) since 80's, this topic is still actual nowadays. Recently several path-based de-noising methods were proposed [3–6] which represent a state of the art in this field. In this paper a new de-speckling method, resulting from a signal processing viewpoint, is presented and compared to some of the methods mentioned above.

A sustainable future power supply requires high fuel-to-electricity conversion efficiencies even in small-scale power plants. A promising technology to reach this goal is a hybrid power plant in which a gas turbine (GT) is coupled with a solid oxide fuel cell (SOFC). This paper presents a dynamic model of a pressurized SOFC system consisting of the fuel cell stack with combustion zone and balance-of-plant components such as desulphurization, humidification, reformer, ejector and heat exchangers. The model includes thermal coupling between the different components. A number of control loops for fuel and air flows as well as power management are integrated in order to keep the system within the desired operation window. Models and controls are implemented in a MATLAB/SIMULINK environment. Different hybrid cycles proposed earlier are discussed and a preferred cycle is developed. Simulation results show the prospects of the developed modeling and control system.

In 2010 the German Aerospace Center (DLR) will conduct the second experiment of the DLR hypersonic SHarp Edge Flight EXperiment Program SHEFEX-2. The purpose is to investigate possible new shapes for future launcher or re-entry vehicles with faceted surfaces and sharp edges and to demonstrate key technologies for re-entry like hypersonic ight control using steerable canard ns. Accurate control of the vehicle using the canards requires a highly accurate knowledge of the angle of attack and the side slip angle. Both angles can only be derived from the ight path and an attitude measurement. The rst can be achieved using GPS measurements. The second can be provided only by the most accurate Inertial Navigation Systems (INS) because drifts due to launch vibrations exceed the accuracy requirements. Therefore, a star tracker will be used to update the attitude information shortly before entry. The SHEFEX-2 mission describes an entry scenario which is applicable to other entry missions. There is a general need to develop a high accuracy integrated navigation system which can be used for multiple missions. This navigation system should combine the measurements from an inertial measurement unit (IMU), GPS receiver and star tracker with the option to include additional sensors. This paper will describe the concept of the integrated navigation system with a focus on integrating the star tracker into the SHEFEX-2 experiment.

This paper addresses the non-iterative quality phase gradient autofocus (QPGA) technique which was originally proposed to remove one-dimensional phase errors in spotlight-mode synthetic aperture radar (SAR) imagery. By enriching the source pool, the method is modified in a way suitable for autofocus in stripmap-mode SAR system with the advantage of being independent of any priori assumptions. Unlike the QPGA the potential candidates, i.e., dominant scatterers located along azimuth in each specific range bin, are automatically selected by exploiting the one-dimensional RELAX algorithm. Furthermore, RELAX is capable of estimating the size of blur window which is, in fact, associated with the Doppler spread of signal spectrum. The corresponding model includes four parameters i.e., complex amplitude, delay, Doppler center and spectral width. The proposed method has been applied to data extracted by a ground-based rotating coherent Doppler radar operating in strip-mapping mode SAR, with the aim of high-resolution clutter detection.

The current paper describes DLR’s optimizer AutoOpti, the implementation of the metamodel “Kriging” as accelerating technique, and the process chain in the automated, multidisciplinary optimization of fans and compressors on basis of a recent full stage optimization of a highly loaded, transonic axial compressor. Methods and strategies for an aerodynamic performance map optimization coupled with a finite element analysis on the structural side are presented. The high number of 231 free design parameters, a very limited number of CFD simulations, and conflicting demands both within the aerodynamic requirements and between the disciplines are a challenging optimization task. To navigate such a multi-dimensional search space, metamodels have successfully been used as accelerating technique. Using four aerodynamic operating points at two rotational speeds allows adjusting a required stability margin and optimizing the working line performance under this constraint. The investigated compressor concept is a highly loaded transonic stage with a single row rotor and a tandem stator, designed for a very high total pressure ratio. A. Introduction ompressors for aircraft engines are constantly developed towards higher aerodynamic loading to reduce the installation length, weight, and number of parts with no degradation in efficiency. This leads to more complex geometries and consequently to more complex flow structures. An automated optimization approach is to be preferred in order to take advantage of new design freedoms, while reducing or at least maintaining development time. Automated optimization is also suggested by recent progress in simulation technologies in several fields such as steady and unsteady computational fluid dynamics (CFD), structural and thermal finite element analysis (FEM). Moreover, processors have become increasingly powerful, and parallel computing on huge clusters can be considered state of the art technology for CFD and FEM applications. Thus, it has become possible to employ optimization methods in the design of various parts of heavy duty gas turbines and aircraft engines, even when calculations require large computational resources.