Search

Nowadays, formal methods are used in various areas for the verification of programs or for code generation from models in order to increase the quality of software and to reduce costs. However, there are still fields in which formal methods have not been widely adopted, despite the large set of possible benefits offered. This is the case for the area of programmable logic controllers (PLC). This article aims to evaluate the potential of formal methods in the context of PLC development. For this purpose, the general concepts of formal methods are first introduced and then transferred to the PLC area, resulting in an engineering-oriented description of the technology that is based on common concepts from PLC development. Based on this description, PLC professionals with varying degrees of experience were interviewed for their perspective on the topic and to identify possible use cases within the PLC domain. The survey results indicate the technology's high potential in the PLC area, either as a tool to directly support the developer or as a key element within a model-based systems engineering toolchain. The evaluation of the survey results is performed with the aid of a demo application that communicates with the Totally Integrated Automation Portal from Siemens and generates programs via Fastsynth, a model-based open source code generator. Benchmarks based on an industry-related PLC project show satisfactory synthesis times and a successful integration into the workflow of a PLC developer., Comment: 8 pages, 6 figures, 1 table. Accepted for publication at IEEE INDIN 2021

In this paper an efficient wideband Direction of Arrival (DoA) and frequency estimation technique is presented which uses only a single snapshot from a multi-beam antenna array. The simultaneous spatial beams (beamspace) are created by a Rotman lens which is composed of a free-space true time delay network attached to a Uniform Linear Array (ULA) of broadband Vivaldi antenna elements. The proposed technique uses machine learning techniques to establish an optimal Neural Network (NN) configuration obtained with a training set. To improve the spatial and frequency space resolution a further estimation stage follows to the NN topology. This results in a lower computational load during the training phase and finally a very fast estimation of direction and frequency of the impinging signal. The performance is evaluated by measurements obtained in an anechoic chamber.

Distributed sensor/radar networks offers several benefits over monostatic systems. For instance, as targets are observed from different aspects angles the detection performance and estimation accuracy of position and speed (Doppler) is improved. Furthermore, a sensor network is able to cope with an increased number of targets. Due to this the interest in such systems has increased over the past years. Moreover, steep improvements in technology and data processing have generated new aspects and fields of application to emerge.

In this study, we evaluate hydrogels based on oxidized hyaluronic acid, cross-linked with adipic acid dihydrazide, for their suitability as bioinks for 3D bioprinting. Aldehyde containing hyaluronic acid (AHA) is synthesized and cross-linked via Schiff Base chemistry with bifunctional adipic acid dihydrazide (ADH) to form a mechanically stable hydrogel with good printability. Mechanical and rheological properties of the printed and casted hydrogels are tunable depending on the concentrations of AHA and ADH cross-linkers.

A surveillance systems based on passive radar technique with distributed node has several advantages compared to traditional monostatic radar systems. For instance, a target will be illuminated and observed from different aspects angles. This improves the detection performance and the range/Doppler estimation. A distributed network topology of the surveillance system allows to increase the number of targets which the system can manage simultaneously. From the operators point of view a passive system has the advantage that no electromagnetic energy is emitted and, hence, there is no hassle with any frequency license and the power consumption is low. Investigations have shown that digital broadcast communication stations like DAB-T or DVB-T are very promising illuminator of opportunity for such a system due to their signal modulation characteristic and their possibility to establish a single frequency distributed radar network. An l1 minimization approach is described within this paper for a single frequency passive radar surveillance network. In real scenarios most objects are spread out over several range/Doppler cells due to their size and/or owing to their motion over the coherent integration time. The presented approach is enhanced in such a way that measurements inaccuracies and the effects of extended targets are taken into account.

Passive radar networks offer several advantages compared to standard single radar. For instance a target is illuminated from different aspect angles and this leads to an increase of the detection performance and higher position estimation accuracy. Beside these both improvements the network is able to cope with an increased number of targets and the range/Doppler resolution is enhanced. As the system does not emit any electromagnetic energy the operator has no hassle with a frequency license. A very promising constellation of such a passive radar network uses digital broadcast communication stations like DAB-T or DVB-T which forms a single frequency network. This paper describes a new approach for evaluating data from a passive Multiple-Input-Single-Output (MISO) radar network based on single frequency network (SFN) by employing group sparsity techniques known from Compressive Sensing. When real targets are huge airplanes, observed during their take-off and touchdown phase, the received echoes are spread out over several range/Doppler cells. The proposed methods takes this into account.

The 29 papers in this special issue cover the most topical research areas in SAR techniques and technologies, such as bistatic SAR, innovative system concepts, polarimetric systems and data analysis, polarimetric SAR interferometry, and advanced processing techniques for image generation and information extraction.

It is a pleasure to introduce this special section of the IEEE Transactions on Aerospace and Electronic Systems (T-AES), linked to the 1st International Workshop on Compressive Sensing applied to Radar/SAR (CoSeRa), which was held in Bonn, Germany, in May 2012. During this workshop more than 40 scientists and researchers from all over the world presented their ongoing work in this area. The program, running over three days, was completed by the keynote speeches from Thomas Strohmer and Gilda Schirinzi.

Nearly 40 young students and scientists from all comers of the world congregated from July 17-23, 2010, to participate in the 2nd International Summer School on RadariSAR. This was organized by Fraunhofer-FHR in cooperation with renowned experts from across Europe and Canada. The program, a combination of the experts' creativity and scientific prowess, had a strong appeal for young scientists (particularly PhD candidates) across the globe, as more applications registered for it than it could cater to. The organizers succeeded in striking the proper balance among lectures, practical workshops, and the leisure activities that are an essential component for creating and sustaining an atmosphere conducive to learning and for binding with new colleagues.