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Institute
- Fakultät I - Elektro- und Informationstechnik (30) (remove)
Our research project, "Rationalizing the virtualization of botanical document material and their usage by process optimization and automation (Herbar-Digital)" started on July 1, 2007 and will last until 2012. Its long-term aim is the digitization of the more than 3,5 million specimens in the Berlin Herbarium. The University of Applied Sciences and Arts in Hannover collaborates with the department of Biodiversity Informatics at the BGBM (Botanic Garden and Botanical Museum Berlin-Dahlem) headed by Walter Berendsohn. The part of Herbar-Digital here presented deals with the analysis of the generated high resolution images (10,400 lines x 7,500 pixel).
The methods developed in the research project "Herbar Digital" are to help plant taxonomists to master the great amount of material of about 3.5 million dried plants on paper sheets belonging to the Botanic Museum Berlin in Germany. Frequently the collector of the plant is unknown. So a procedure had to be developed in order to determine the writer of the handwriting on the sheet. In the present work the static character is transformed into a dynamic form. This is done with the model of an inert ball which is rolled through the written character. During this off-line writer recognition, different mathematical procedures are used such as the reproduction of the write line of individual characters by Legendre polynomials. When only one character is used, a recognition rate of about 40% is obtained. By combining multiple characters, the recognition rate rises considerably and reaches 98.7% with 13 characters and 93 writers (chosen randomly from the international IAM-database [3]). Another approach tries to identify the writer by handwritten words. The word is cut out and transformed into a 6-dimensional time series and compared e.g. by means of DTW-methods. A global statistical approach using the whole handwritten sentences results in a similar recognition rate of more than 98%. By combining the methods, a recognition rate of 99.5% is achieved.
The research project "Herbar Digital" was started in 2007 with the aim to digitize 3.5 million dried plants on paper sheets belonging to the Botanic Museum Berlin in Germany. Frequently the collector of the plant is unknown, so a procedure had to be developed in order to determine the writer of the handwriting on the sheet. In the present work the static character was transformed into a dynamic form. This was done with the model of an inert ball which was rolled along the written character. During this off-line writer recognition, different mathematical procedures were used such as the reproduction of the write line of individual characters by Legendre polynomials. When only one character was used, a recognition rate of about 40% was obtained. By combining multiple characters, the recognition rate rose considerably and reached 98.7% with 13 characters and 93 writers (chosen randomly from the international IAM-database [3]). A global statistical approach using the whole handwritten text resulted in a similar recognition rate. By combining local and global methods, a recognition rate of 99.5% was achieved.
An important part of computed tomography is the calculation of a three-dimensional reconstruction of an object from series of X-ray images. Unfortunately, some applications do not provide sufficient X-ray images. Then, the reconstructed objects no longer truly represent the original. Inside of the volumes, the accuracy seems to vary unpredictably. In this paper, we introduce a novel method to evaluate any reconstruction, voxel by voxel. The evaluation is based on a sophisticated probabilistic handling of the measured X-rays, as well as the inclusion of a priori knowledge about the materials that the object receiving the X-ray examination consists of. For each voxel, the proposed method outputs a numerical value that represents the probability of existence of a predefined material at the position of the voxel while doing X-ray. Such a probabilistic quality measure was lacking so far. In our experiment, false reconstructed areas get detected by their low probability. In exact reconstructed areas, a high probability predominates. Receiver Operating Characteristics not only confirm the reliability of our quality measure but also demonstrate that existing methods are less suitable for evaluating a reconstruction.
Industrial Control Systems (ICS) succumb to an ever evolving variety of threats. Additionally, threats are increasing in number and get more complex. This requires a holistic and up-to-date security concept for ICS as a whole. Usually security concepts are applied and updated based on regularly performed ICS security assessments. Such ICS security assessments require high effort and extensive knowledge about ICS and its security. This is often a problem for small and mediumsized enterprises (SME), which do not have sufficient respective sufficiently skilled human resources. This paper defines in a first step requirements on the knowledge needed to perform an ICS security assessment and the life cycle of this knowledge. Afterwards the ICS security knowledge and its life cycle are developed and discussed considering the requirements and related work.
This document concerns IT security in production facilities. It is intended for small and medium-sized enterprises that are looking for a simple procedural model for ensuring IT security in production areas.
In order to raise readers’ awareness of IT security in production facilities, security incidents are presented in section 2. It is clear that cyber attacks on production facilities in this day and age are not random, but are instead based on a targeted process.
An overview of the most important standards and recommendations on the topic of “IT security in production” then follows in section 3.
Section 4 develops a concept for setting up an IT security system for small and medium-sized enterprises (SMEs) on the basis of a ten-point plan. The focus is not only on technical measures, but also in particular on the most frequently neglected organizational measures.
Section 5 then describes the outlook for future requirements and solutions in the context of Industry 4.0.
Quartz-crystal microbalances (QCMs) are commercially available mass sensors which mainly consist of a quartz resonator that oscillates at a characteristic frequency, which shifts when mass changes due to surface binding of molecules. In addition to mass changes, the viscosity of gases or liquids in contact with the sensor also shifts the resonance but also influences the quality factor (Q-factor). Typical biosensor applications demand operation in liquid environments leading to viscous damping strongly lowering Q-factors. For obtaining reliable measurements in liquid environments, excellent resonator control and signal processing are essential but standard resonator circuits like the Pierce and Colpitts oscillator fail to establish stable resonances. Here we present a lowcost, compact and robust oscillator circuit comprising of state-of-the-art commercially available surface-mount technology components which stimulates the QCMs oscillation, while it also establishes a control loop regulating the applied voltage. Thereby an increased energy dissipation by strong viscous damping in liquid solutions can be compensated and oscillations are stabilized. The presented circuit is suitable to be used in compact biosensor systems using custom-made miniaturized QCMs in microfluidic environments. As a proof of concept we used this circuit in combination with a customized microfabricated QCM in a microfluidic environment to measure the concentration of C-reactive protein (CRP) in buffer (PBS) down to concentrations as low as 5 μgmL -1.
Toward a service-based workflow for automated information extraction from herbarium specimens
(2018)
Over the past years, herbarium collections worldwide have started to digitize millions of specimens on an industrial scale. Although the imaging costs are steadily falling, capturing the accompanying label information is still predominantly done manually and develops into the principal cost factor. In order to streamline the process of capturing herbarium specimen metadata, we specified a formal extensible workflow integrating a wide range of automated specimen image analysis services. We implemented the workflow on the basis of OpenRefine together with a plugin for handling service calls and responses. The evolving system presently covers the generation of optical character recognition (OCR) from specimen images, the identification of regions of interest in images and the extraction of meaningful information items from OCR. These implementations were developed as part of the Deutsche Forschungsgemeinschaft funded a standardised and optimised process for data acquisition from digital images of herbarium specimens (StanDAP-Herb) Project.
The growing importance of renewable generation connected to distribution grids requires an increased coordination between transmission system operators (TSOs) and distribution system operators (DSOs) for reactive power management. This work proposes a practical and effective interaction method based on sequential optimizations to evaluate the reactive flexibility potential of distribution networks and to dispatch them along with traditional synchronous generators, keeping to a minimum the information exchange. A modular optimal power flow (OPF) tool featuring multi-objective optimization is developed for this purpose. The proposed method is evaluated for a model of a real German 110 kV grid with 1.6 GW of installed wind power capacity and a reduced order model of the surrounding transmission system. Simulations show the benefit of involving wind farms in reactive power support reducing losses both at distribution and transmission level. Different types of setpoints are investigated, showing the feasibility for the DSO to fulfill also individual voltage and reactive power targets over multiple connection points. Finally, some suggestions are presented to achieve a fair coordination, combining both TSO and DSO requirements.