Open Access

In a recent paper it has been shown that the effective nonlinear constant which is used in a P-Matrix approach to describe third-order intermodulation (IMD3) in surface acoustic wave (SAW) devices can be obtained from finite element (FEM) calculations of a periodic cell using nonlinear tensor data [1]. In this paper we extend this FEM calculation and show that the IMD3 of an infinite periodic array of electrodes on a piezoelectric substrate can be directly simulated in the sagittal plane. This direct approach opens the way for a FEM based simulation of nonlinearities for finite and generalized structures avoiding the simplifications of phenomenological approaches.

Eine neue Prozessidee zur Auftrennung racemischer Wirkstoffe unter Verwendung nanoskaliger AlO(OH)‐Hohlkugeln als Adsorbens und überkritischen Kohlenstoffdioxides (sc‐CO2) als Lösungsmittel wird vorgestellt. Zur Auslegung des Prozesses werden Untersuchungen zur Abscheidung der racemischen Wirkstoffe (RS)‐Flurbiprofen, (RS)‐Ibuprofen, (RS)‐Ketoprofen und den reinen Enantiomeren (R)‐Flurbiprofen, (S)‐Ibuprofen und (S)‐Ketoprofen an AlO(OH)‐Hohlkugeln präsentiert und bewertet. Zudem werden Adsorptionsdaten von gasförmigem CO2 an den Hohlkugeln und kommerziellen AlO(OH)‐Partikeln, die mit einer Magnetschwebewaage ermittelt wurden, verglichen. Abschließend werden erste Ergebnisse von orientierenden Versuchen zur Adsorption von racemischem Flurbiprofen aus sc‐CO2 an den Hohlkugeln vorgestellt.

Enthält die Artikel: "Smoothie:a solution for device and content independent applications including 3D imaging as content" von Razia Sultana und Andreas Christ, S. 13-18 "Future of Logging in the Crisis of Cloud Security", von Sai Manoj Marepalli, Razia Sultana und Andreas Christ, S. 60-64

We propose secure multi-party computation techniques for the distributed computation of the average using a privacy-preserving extension of gossip algorithms. While recently there has been mainly research on the side of gossip algorithms (GA) for data aggregation itself, to the best of our knowledge, the aforementioned research line does not take into consideration the privacy of the entities involved. More concretely, it is our objective to not reveal a node's private input value to any other node in the network, while still computing the average in a fully-decentralized fashion. Not revealing in our setting means that an attacker gains only minor advantage when guessing a node's private input value. We precisely quantify an attacker's advantage when guessing - as a mean for the level of data privacy leakage of a node's contribution. Our results show that by perturbing the input values of each participating node with pseudo-random noise with appropriate statistical properties (i) only a minor and configurable leakage of private information is revealed, by at the same time (ii) providing a good average approximation at each node. Our approach can be applied to a decentralized prosumer market, in which participants act as energy consumers or producers or both, referred to as prosumers.

This work describes a camera-based method for the calibration of optical See-Through Glasses (STGs). A new calibration technique is introduced for calibrating every single display pixel of the STGs in order to overcome the disadvantages of a parametric model. A non-parametric model compared to the parametric one has the advantage that it can also map arbitrary distortions. The new generation of STGs using waveguide-based displays [5] will have higher arbitrary distortions due to the characteristics of their optics. First tests show better accuracies than in previous works. By using cameras which are placed behind the displays of the STGs, no error prone user interaction is necessary. It is shown that a high accuracy tracking device is not necessary for a good calibration. A camera mounted rigidly on the STGs is used to find the relations between the system components. Furthermore, this work elaborates on the necessity of a second subsequent calibration step which adapts the STGs to a specific user. First tests prove the theory that this subsequent step is necessary.

Android is an operating system which was developed for use in smart mobile phones and is the current leader in this market. A lot of efforts are being spent to make Android available to the embedded world, as well. Many embedded systems do not have a local GUI and are therefore called headless devices. This paper presents the results of an analysis of the general suitability of Anroid in headless embedded systems and ponders the advantages and disadvantages. It focuses on the hardware related issues, i.e. to what extent Android supports hardware peripherals normally used in embedded systems.

Covert and Side-Channels have been known for a long time due to their versatile forms of appearance. For nearly every technical improvement or change in technology, such channels have been (re-)created or known methods have been adapted. For example the introduction of hyperthreading technology has introduced new possibilities for covert communication between malicious processes because they can now share the arithmetic logical unit (ALU) as well as the L1 and L2 cache which enables establishing multiple covert channels. Even virtualization which is known for its isolation of multiple machines is prone to covert and side-channel attacks due to the sharing of resources. Therefore itis not surprising that cloud computing is not immune to this kind of attacks. Even more, cloud computing with multiple, possibly competing users or customers using the same shared resources may elevate the risk of unwanted communication. In such a setting the ”air gap” between physical servers and networks disappears and only the means of isolation and virtual separation serve as a barrier between adversary and victim. In the work at hand we will provide a survey on weak spots an adversary trying to exfiltrate private data from target virtual machines could exploit in a cloud environment. We will evaluate the feasibility of example attacks and point out possible mitigation solutions if they exist.

The design of control systems of concentrator photovoltaic power plants will be more challenging in the future. Reasons are cost pressure, the increasing size of power plants, and new applications for operation, monitoring and maintenance required by grid operators, manufacturers and plant operators. Concepts and products for fixed-mounted photovoltaic can only partly be adapted since control systems for concentrator photovoltaic are considerable more complex due to the required high accurate sun-tracking. In order to assure reliable operation during a lifetime of more than 20 years, robustness of the control system is one crucial design criteria. This work considers common engineering technics for robustness, safety and security. Potential failures of the control system are identified and their effects are analyzed. Different attack scenarios are investigated. Outcomes are design criteria that encounter both: failures of system components and malicious attacks on the control system of future concentrator photovoltaic power plants. Such design criteria are a transparent state management through all system layers, self-tests and update capabilities for security concerns. The findings enable future research to develop a more robust and secure control system for concentrator photovoltaics when implementing new functionalities in the next generation.

The research project Ko-TAG [2], as part of the research initiative Ko-FAS [1], funded by the German Ministry of Economics and Technologies (BMWi), deals with the development of a wireless cooperative sensor system that shall pro-vide a benefit to current driver assistance systems (DAS) and traffic safety applications (TSA). The system’s primary function is the localization of vulnerable road users (VRU) e.g. pedestrians and powered two-wheelers, using communication signals, but can also serve as pre-crash (surround) safety system among vehicles. The main difference of this project, compared to previous ones that dealt with this topic, e.g. the AMULETT project, is an underlying FPGA based Hardware-Software co-design. The platform drives a real-time capable communication protocol that enables highly scalable network topologies fulfilling the hard real-time requirements of the single localization processes. Additionally it allows the exchange of further data (e.g. sensor data) to support the accident pre-diction process and the channel arbitration, and thus supports true cooperative sensing. This paper gives an overview of the project’s current system design as well as of the implementations of the key HDL entities supporting the software parts of the communication protocol. Furthermore, an approach for the dynamic reconfiguration of the devices is described, which provides several topology setups using a single PCB design.

Currently, QRS width and bundle branch block morphology are used as electrocardiographic guideline criterias to selectheart failure (HF) patients with interventricular desynchronization in sinus rhythm (SR) for cardiac resynchronisationtherapy (CRT). Nevertheless, up to 30% of these patients do not benefit from implantation of CRT systems. Esophagealleft ventricular electrogram (LVE) enables semi-invasive measurement of interventricular conduction delays (IVCD)even in patients with atrial fibrillation (AF). To routinely apply this method, a programmer based semi-invasiveautomatic quantification of IVCD should to be developed. Our aims were todefine interventricular conduction delaysby analyzing fractionated left ventricular (LV) deflections in the esophageal left ventricular electrogram of HF patientsin SR or AF. In 66 HF patients (49 male,17 female, age 65 ± 10 years) a 5F TOslim electrode (Osypka AG, Germany) was perorallyapplied. Using BARD EP Lab, cardiac desynchronization was quantified as interval IVCD between onset of QRS insurface ECG and the investigator-determined onset of the left ventricular deflection in LVE. IVCD was compared withthe intervals between QRS onset and the first maximum (IVCDm1) and between QRS onset and the second maximum(IVCDm2) of the LV complex. QRS of 173 ± 26 ms was linked with empirical IVCD of 75 ± 25 ms, at mean. First and second LV maximum could beascertained beyond doubt in all patients. Significant correlations of the p<0,01 level were found between IVCD and theIVCDm1 of 96 ± 28 ms as well as between IVCD and the IVCDm2 of 147 ± 31 ms, at mean. To standardize automatic measurement of interventricular conduction delays with respect to patients with fractionatedLV complexes, the first maximum of the LV deflection should be utilized to qualify the IVCD of HF patients with sinusrhythm and atrial fibrillation.

This study presents some results from a monitoring project with night ventilation and earthto-air heat exchanger. Both techniques refer to air-based low-energy cooling. As these technologies are limited to specific boundary conditions (e.g. moderate summer climate, low temperatures during night, or low ground temperatures, respectively), water-based low-energy cooling may be preferred in many projects. A comparison of the night-ventilated building with a ground-cooled building shows major differences in both concepts.

Cardiac resynchronization therapy (CRT) with biventricular (BV) pacing is an established therapy in approximately two-thirds of symptomatic heart failure (HF) patients (P) with left bundle branch block (LBBB). The aim of this study was to evaluate left atrial (LA) conduction delay (LACD) and left ventricular (LV) conduction delay (LVCD) using pre-implantational transesophageal electrocardiography (ECG) in sinus rhythm (SR) CRT responder (R) and non-responder (NR). Methods: SR HF P (n=52, age 63.6±10.4 years; 6 females, 46 males) with New York Heart Association (NYHA) class 3.0±0.2, 24.4±7.1 % LV ejection fraction and 171.2±37.6 ms QRS duration (QRSD) were measured by bipolar filtered transesophageal LA and LV ECG recording with hemispherical electrodes (HE) TO catheter (Osypka AG, Rheinfelden, Germany). LACD was measured between onset of P-wave in the surface ECG and onset of LA deflection in the LA ECG. LVCD was measured between onset of QRS in the surface ECG and onset of LV deflection in the LV ECG. Results: There were 78.8 % SR CRT R (n=41) with 171.2±36.9 ms QRSD, 73.3±25.7 ms LACD, 80.0±24.0 ms LVCD and 2.3±0.5 QRSD-LVCD-ratio. SR CRT R QRSD correlated with LACD (r=0.688, P<0.001) and LVCD (r=0.699, P<0.001). There were 21.2 % SR CRT NR (n=11) with 153.4±22.4 ms QRSD (P=0.133), 69.8±24.8 ms LACD (n=6, P=0.767), 54.2±31.0 ms LVCD (P<0.0046) and 3.9±2.5 QRSD-LVCD-ratio (P<0.001). SR CRT NR QRSD not corre-lated with IACD (r=-0.218, P=0.678) and IVCD (r=0.042, P=0.903). During a 22.8±21.3 month CRT follow-up, the CRT R NYHA class improved from 3.1±0.3 to 1.9±0.3 (P<0.001). In CRT NR, NYHA class not improved (2.9±0.4 to 2.9±0.2, P=1) during 11.2±9.8 months BV pacing. Conclusions: Transesophageal LA and LV ECG with HE can be utilized to analyse LACD and LVCD in HF P. Pre-implantational LVCD and QRSD-LVCD-ratio may be additional useful parameters to improve P selection for SR CRT.

Cardiac resynchronisation therapy (CRT) with biventricular pacing (BV) is an established therapy for heart failure (HF) patients with interventricular conduction delay (IVCD). The aim of the study was to evaluate transesophageal IVCD and left ventricular (LV) pacing with directed electrical pacing field (EPF) in HF patients. Methods: HF patients were analysed with bipolar transesophageal LV electrocardiogram recording and LV pacing with constant voltage stimulus output, 4 ms stimulus duration, distal cylindrical electrode (CE) and seven 6 mm hemispherical electrodes (HE) with 15 mm electrode distance (TO, Dr. Osypka, Rheinfelden, Germany). Results: LV electrocardiogram recording with HE-HE and CE-HE evaluated a mean IVCD of 79.9 ± 36.7 ms. Directed EPF with CE-HE and HE-HE allowed LV VAT (n=12) and LV D00 pacing (n=5) with a mean effective capture output of 97.35 ± 6.64 V. In 15 responders with IVCD of 87 ± 33 ms arterial pulse pressure (PP) increased from 65 ± 24 mmHg to 79 ± 27 mmHg (p < 0.001). EPF was simulated with finite element method. Conclusions: Transesophageal LV electrocardiography and directed EPF pacing with CE and HE allowed the evaluation of IVCD and PP to select patients for BV pacing.

Introduction: Cardiac resynchronization therapy (CRT) with left ventricular (LV) pacing is an established therapy for heart failure (HF) patients (P) with ventricular desynchronisation and reduced LV ejection fraction (EF). The aim of this study was to test the utilization of the transesophageal approach to measure arterial pulse pressure (PP) during LV pacing and electrical interventricular conduction delay (IVCD), to better select patients for CRT. Methods: 32 HF patients (age 64 ± 10 years; 5 females, 27 males) with New York Heart Association (NYHA) class 2.8 ± 0.6, 27 ± 11 % LV EF and 155 ± 35 ms QRS duration were analysed with semi-invasive left cardiac pacing and electrocardiography. Esophageal TO8 Osypka catheter of 10.5 F diameter was perorally applied to the esophagus and placed in the position of maximum left atrial (LA) deflection and maximum LV deflection to measure PP with VAT or D00 pacing modes. Results: Temporary transesophageal LV pacing was possible with VAT mode (n=16) and D00 mode (n=16) in all patients. In 15 Δ-PP-responders, PP was higher during LV pacing on than LV pacing off (78.3 ± 26.6 versus 65.9 ± 23.7 mmHg, P < 0.001) and NYHA class improved from 3.1 ± 0.35 to 2.1 ± 0.35 (P < 0.001) during 29 ± 26 month biventricular (BV) pacing follow-up (6 Medtronic and 9 Boston BV pacing devices). In 17 Δ-PP-non-responders, PP was not higher during LV pacing on than LV pacing off (61.5 ± 23.9 versus 60.9 ± 23.5 mmHg, P = 0.066). IVCD was significant longer in Δ-PP-responders than in Δ-PP-non-responders (87 ± 33 ms versus 37± 29 ms, P < 0.001). Conclusion: Semi-invasive transesophageale LA and LV pacing with D00 and VAT mode and LV electrogram recording may be useful techniques to predict CRT improvement.

Introduction: Cardiac resynchronisation therapy (CRT) with atrioventricular (AV) and interventricular (VV) optimized biventricular pacing (BV) is an established therapy for heart failure (HF) patients with electrical interventricular conduction delay (IVCD). The aim of the study was to compare AV and VV delay optimization with cardiac output (CO) and acceleration index (ACI) impedance cardiographic (ICG) methods. Methods: HF patients with IVCD 86.8 ± 33 ms (n=15, age 66 ± 10 years; 2 females, 13 males), New York Heart Association (NYHA) functional class 3.1 ± 0.4, left ventricular (LV) ejection fraction 21.3 ± 7.8 % and QRS duration 176.1 ± 31.7 ms underwent AV and VV delay optimization with CO and ACI methods (Cardioscreen, Medis GmbH, Ilmenau, Germany). After evaluation of optimal AV delay, we evaluated optimal VV delay during simultaneous LV and right ventricular (RV) pacing (LV=RV), LV before RV pacing (LV-RV) and RV before LV pacing (RV-LV). Results: Optimal VV delay was -12.3 ± 25.9 ms LV-RV pacing with VV delay range from -80 ms LV-RV pacing to +20 ms RV-LV pacing and RV=LV pacing. Optimal AV delay after atrial sensing was 108.6 ± 20.3 ms (n=14) and optimal AV delay after atrial pacing 190 ± 14.1 ms (n=2) with AV delay range from 80 ms to 200 ms. RV versus BV pacing mode resulted in improvement of CO from 3.4 ± 1.2 l/min to 4.4 ± 1.4 l/min (p<0.001) and ACI from 0.667 ± 0.227 1/s² to 0.834 ± 0.282 1/s² (p<0.002). During 34 ± 26 month BV pacing, the NYHA class improved from 3.1 ± 0.4 to 2.1 ± 0.4 (p<0.001). Conclusion: AV and VV delay optimized BV pacing acutely improve ICG CO and ACI and their NYHA class during long-term follow-up. ICG may be a simple and useful technique to optimize AV and VV delay in CRT.