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Merseburg, Germany

The Merseburg University of Applied science - University of Applied science) is a higher education institution located in the town of Merseburg, Germany. It was established on April 1, 1992. Its precursor was the Technical University Leuna-Merseburg . Wikipedia.

Jenderka K.-V.,Physikalisch - Technische Bundesanstalt | Jenderka K.-V.,Merseburg University of Applied Sciences | Wilkens V.,Physikalisch - Technische Bundesanstalt
Metrologia | Year: 2012

The reliable description of the ultrasonic fields of high-intensity therapeutic ultrasound (HITU) devices is a prerequisite concerning the safe application of the method in the daily clinical routine. Since ultrasonic sensors used for the characterization of diagnostic fields are at high risk of being damaged in the strong therapeutic fields, the measurements are carried out in burst mode to reduce the acting temporal-average intensities. For the thorough investigation of possible differences between the excitation in continuous wave (cw) and burst mode, the temporal-average total acoustic output powers of two types of HITU transducers with f-numbers of approximately 1 and with working frequencies between 1.1MHz and 3.3MHz were investigated by means of a radiation force balance. The maximum cw equivalent power level was 300W; the duty cycles varied between 1% and 90%. In addition, the possible effect of the transducer-target distance was investigated. It was found that the different turn-on and turn-off behaviour of the transducers caused variations of the effective duty cycle, depending on the power level and the power amplifier used. The temporal-average power declined with increasing distance as expected, and no focal anomaly was detected. © 2012 BIPM & IOP Publishing Ltd. Source

The pressure in the impeller, in the side channel and in the breaker of a side channel compressor with the polytropic compression and with the polytropic expansion of the breaker mass flow was investigated experimentally, and the occurring shock waves were detected during the expansion of the gas in the breaker. Thereby different pressure flows occur at the four measuring points in blade channel on the blade pressure and suction side of the related radius from ri/r2 = 0.80 and ri/r2 = 0.95, which give an indication of the blade channel flow. In addition to the periodic increase in pressure and the gas expansion in the breaker, the superimposed pressure oscillation in the side channel is caused by the blade rotation frequency. This superimposed pressure oscillation can be decomposed by Fourier transformation in the two pressure oscillation components. These phenomena are the reason for the more accurate investigation of the pressure flow in the blade channel during the polytropic compression and expansion of the breaker mass flow. The gradient of the effective values of the gas pressure oscillation in the blade channel leads not only to the operating characteristics of the side channel compressor Δp = f(φ, n), but also to the breaker curve characteristic ΔpU = f(φ, n). © Springer-Verlag 2011. Source

Sonography is based on multiple interactions between ultrasonic waves and the tissue during propagation. Therefore, ultrasound images contain more information than the mere visualization of the anatomic structures. Assessing the different echogenicity and texture of tissue regions yields additional information about the pathologic tissue alterations. Precise interpretation requires knowledge of the whole process of image generation. This also applies for the adjustment of system parameters for image improvement. This article explains the phenomena of ultrasound propagation in tissue and the principles of ultrasound image generation-from the scan head to the image on the screen. © 2013 Springer-Verlag Berlin Heidelberg. Source

Ringeisen T.,Merseburg University of Applied Sciences | Raufelder D.,Free University of Berlin
Journal of Adolescence | Year: 2015

This study examined gender-specific relationships between adolescents' perceptions of school-related support/pressure from their parents and test anxiety. A sample of German students (N = 845; Mage = 15.32; SD = .49) completed questionnaires that measured their perceived parental support/pressure (for mother and father separately) as well as the four main components of test anxiety (worry, interference, lack of confidence, and emotionality). Gender-specific relations were identified using multigroup structural equation modeling: For girls, perceived maternal pressure was positively associated with emotionality and interference; for boys, perceived father pressure and father support were positively associated with interference and worry, respectively. For both genders, perceived mother pressure and support were related to lack of confidence. Our findings suggest that adolescents' perceptions of maternal attitudes are associated with students' self-confidence irrespective of the child's gender, whereas the remaining facets of test anxiety follow same-sex trajectories between perceived parental attitudes and adolescents' test anxiety. © 2015 The Foundation for Professionals in Services for Adolescents. Source

Linde B.B.J.,University of Gdask | Rosenfeld E.,Merseburg University of Applied Sciences
Journal of the Acoustical Society of America | Year: 2011

Similarities and differences in vibrational behavior of two guitars having a symmetric Torres bracing pattern and an asymmetric pattern forming a lattice on a soundboard are investigated by means of the modal analysis technique and laser Doppler vibrometry (LDV) measurements. Instruments are investigated before and after a bridge and strings assembling (i.e., they are incomplete or complete). The bracing pattern and the absence/presence of the bridge and strings have some effect on modal frequencies and mode shapes. The bracing pattern does not affect the sequence of at least first three low frequency mode shapes of incomplete/complete instruments but affects their modal frequencies. Depending on frequency, the bridge behaves either as a rigid or a flexible structure. © 2011 Acoustical Society of America. Source

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