TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Zimmermann, E.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - Pulse recording by free-running sampling
JF  - IEEE Transactions on Nuclear Science
N2  - Pulses from a position-sensitive photomultiplier (PS-PMT) are recorded by free-running ADCs at a sampling rate of 40 MHz. A four-channel acquisition board has been developed which is equipped with four 12-bit ADCs connected to one field programmable gate array (FPGA). The FPGA manages data acquisition and the transfer to the host computer. It can also work as a digital trigger, so a separate hardware trigger can be omitted. The method of free-running sampling provides a maximum of information, besides the pulse charge and amplitude also pulse shape and starting time are contained in the sampled data. This information is crucial for many tasks such as distinguishing between different scintillator materials, determination of radiation type, pile-up recovery, coincidence detection or time-of-flight applications. The absence of an analog integrator allows very high count rates to be dealt with. Since this method is to be employed in positron emission tomography (PET), the position of an event is also important. The simultaneous readout of four channels allows localization by means of center-of-gravity weighting. First results from a test setup with LSO scintillators coupled to the PS-PMT are presented here
Y1  - 2001
SN  - 0018-9499
VL  - 48
IS  - 3
SP  - 524
EP  - 526
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Zimmermann, E.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - Pulse recording by free-running sampling
JF  - 2000 IEEE Nuclear Science Symposium Conference Record, Vol. 2
N2  - Pulses from a position-sensitive photomultiplier (PS-PMT) are recorded by free running ADCs at a sampling rate of 40 MHz. A four-channel acquisition-board has been developed which is equipped with four 12 bit-ADCs connected to one FPGA (field programmable gate array). The FPGA manages data acquisition and the transfer to the host computer. It can also work as a digital trigger, so a separate hardware-trigger can be omitted. The method of free running sampling provides a maximum of information, besides the pulse charge and amplitude also pulse shape and starting time are contained in the sampled data. These informations are crucial for many tasks such as distinguishing between different scintillator materials, determination of radiation type, pile-up recovery, coincidence detection or time-of-flight applications. The absence of an analog integrator allows coping with very high count rates. Since this method is going to be employed in positron emission tomography (PET), the position of an event is another important information. The simultaneous readout of four channels allows localization by means of center-of-gravity weighting. First results from a test setup with LSO-scintillators coupled to the PS-PMT are presented
Y1  - 2000
SN  - 1082-3654
SP  - 9/179
EP  - 9/181
ER  - 
TY  - JOUR
A1  - Fink, G. R.
A1  - Marshall, J. C.
A1  - Shah, N. J.
A1  - Weiss, P.H.
A1  - Halligan, P. W.
A1  - Grosse-Ruyken, M.
A1  - Ziemons, Karl
A1  - Zilles, K.
A1  - Freund, H. J.
T1  - Line bisection judgments implicate right parietal cortex and cerebellum as assessed by fMRI
JF  - Neurology
Y1  - 2000
SN  - 1526-632X
VL  - 54
IS  - 6
SP  - 1324
EP  - 1331
ER  - 
TY  - JOUR
A1  - Taylor, J. G.
A1  - Schmitz, N.
A1  - Ziemons, Karl
A1  - Grosse-Ruyken, M.-L.
A1  - Gruber, O.
A1  - Müller-Gärtner, H.-W.
A1  - Shah, N. J.
T1  - The network of brain areas involved in the motion aftereffect
JF  - Neuroimage
N2  - A network of brain areas is expected to be involved in supporting the motion aftereffect. The most active components of this network were determined by means of an fMRI study of nine subjects exposed to a visual stimulus of moving bars producing the effect. Across the subjects, common areas were identified during various stages of the effect, as well as networks of areas specific to a single stage. In addition to the well-known motion-sensitive area MT the prefrontal brain areas BA44 and 47 and the cingulate gyrus, as well as posterior sites such as BA37 and BA40, were important components during the period of the motion aftereffect experience. They appear to be involved in control circuitry for selecting which of a number of processing styles is appropriate. The experimental fMRI results of the activation levels and their time courses for the various areas are explored. Correlation analysis shows that there are effectively two separate and weakly coupled networks involved in the total process. Implications of the results for awareness of the effect itself are briefly considered in the final discussion.
Y1  - 2000
SN  - 1053-8119
VL  - 11
IS  - 4
SP  - 257
EP  - 270
ER  - 
TY  - JOUR
A1  - Weckesser, Martin
A1  - Grießmeier, Martin
A1  - Schmidt, Daniela
A1  - Sonnenberg, Frank
A1  - Ziemons, Karl
A1  - Kemna, Lars
A1  - Holschbach, Marcus
A1  - Langen, Karl-J.
A1  - Müller-Gärtner, Hans-W.
T1  - Iodine-123 α-methyl tyrosine single-photon emission tomography of cerebral gliomas: standardised evaluation of tumour uptake and extent
JF  - European Journal of Nuclear Medicine
N2  - Single-photon emission tomography (SPET) with the amino acid analogue l-3-[123I]iodo-α-methyl tyrosine (IMT) is helpful in the diagnosis and monitoring of cerebral gliomas. Radiolabelled amino acids seem to reflect tumour infiltration more specifically than conventional methods like magnetic resonance imaging and computed tomography. Automatic tumour delineation based on maximal tumour uptake may cause an overestimation of mean tumour uptake and an underestimation of tumour extension in tumours with circumscribed peaks. The aim of this study was to develop a program for tumour delineation and calculation of mean tumour uptake which takes into account the mean background activity and is thus optimised to the problem of tumour definition in IMT SPET. Using the frequency distribution of pixel intensities of the tomograms a program was developed which automatically detects a reference brain region and draws an isocontour region around the tumour taking into account mean brain radioactivity. Tumour area and tumour/brain ratios were calculated. A three-compartment phantom was simulated to test the program. The program was applied to IMT SPET studies of 20 patients with cerebral gliomas and was compared to the results of manual analysis by three different investigators. Activity ratios and chamber extension of the phantom were correctly calculated by the automatic analysis. A method based on image maxima alone failed to determine chamber extension correctly. Manual region of interest analysis in patient studies resulted in a mean inter-observer standard deviation of 8.7%±6.1% (range 2.7%–25.0%). The mean value of the results of the manual analysis showed a significant correlation to the results of the automatic analysis (r = 0.91, P<0.0001 for the uptake ratio; r = 0.87, P<0.0001 for the tumour area). We conclude that the algorithm proposed simplifies the calculation of uptake ratios and may be used for observer-independent evaluation of IMT SPET studies. Three-dimensional tumour recognition and transfer to co-registered morphological images based on this program may be useful for the planning of surgical and radiation treatment.
Y1  - 1998
SN  - 1619-7089
VL  - 25
IS  - 2
SP  - 150
EP  - 156
ER  - 
TY  - JOUR
A1  - Kleines, H.
A1  - Ziemons, Karl
A1  - Zwoll, K.
T1  - Experiences with ATM in a multivendor pilot system at Forschungszentrum Jülich
JF  - IEEE Transactions on Nuclear Science
N2  - The ATM technology for high speed serial transmission provides a new quality of communication by introducing novel features in a LAN environment, especially support of real time communication, of both LAN and WAN communication and of multimedia streams. In order to evaluate ATM for future DAQ systems and remote control systems as well as for a high speed picture archiving and communications system for medical images, Forschungszentrum Julich has build up a pilot system for the evaluation of ATM and standard low cost multimedia systems. It is a heterogeneous multivendor system containing a variety of switches and desktop solutions, employing different protocol options of ATM. The tests conducted in the pilot system revealed major difficulties regarding stability, interoperability and performance. The paper presents motivations, layout and results of the pilot system. Discussion of results concentrates on performance issues relevant for realistic applications, e.g., connection to a RAID system via NFS over ATM
Y1  - 1998
SN  - 0018-9499
VL  - 45
IS  - 4
SP  - 1867
EP  - 1871
ER  - 
TY  - JOUR
A1  - Schmidt, Daniela
A1  - Langen, Karl-J.
A1  - Herzog, Hans
A1  - Wirths, Jochen
A1  - Holschbach, Markus
A1  - Kiwit, Jürgen C. W.
A1  - Ziemons, Karl
A1  - Coenen, Heinz-H.
A1  - Müller-Gärtner, Hans-W.
T1  - Whole-body kinetics and dosimetry of L-3[123I]-iodo-α-methyltyrosine
JF  - European Journal of Nuclear Medicine
Y1  - 1997
SN  - 1619-7089
VL  - 24
IS  - 9
SP  - 1162
EP  - 1166
ER  - 
TY  - JOUR
A1  - Weckesser, Matthias
A1  - Hufnagel, Andreas
A1  - Ziemons, Karl
A1  - Grießmeier, Martin
A1  - Sonnenberg, Frank
A1  - Hackländer, Thomas
A1  - Langen, Karl-J.
A1  - Holschbach, Markus
A1  - Elger, Christian E.
A1  - Müller-Gärtner, Hans-W.
T1  - Effect of partial volume correction on muscarinic cholinergic receptor imaging with single-photon emission tomography in patients with temporal lobe epilepsy
JF  - European Journal of Nuclear Medicine
N2  - Animal experiments and preliminary results in humans have indicated alterations of hippocampal muscarinic acetylcholine receptors (mAChR) in temporal lobe epilepsy. Patients with temporal lobe epilepsy often present with a reduction in hippocampal volume. The aim of this study was to investigate the influence of hippocampal atrophy on the quantification of mAChR with single photon emission tomography (SPET) in patients with temporal lobe epilepsy. Cerebral uptake of the muscarinic cholinergic antagonist [123I]4-iododexetimide (IDex) was investigated by SPET in patients suffering from temporal lobe epilepsy of unilateral (n=6) or predominantly unilateral (n=1) onset. Regions of interest were drawn on co-registered magnetic resonance images. Hippocampal volume was determined in these regions and was used to correct the SPET results for partial volume effects. A ratio of hippocampal IDex binding on the affected side to that on the unaffected side was used to detect changes in muscarinic cholinergic receptor density. Before partial volume correction a decrease in hippocampal IDex binding on the focus side was found in each patient. After partial volume no convincing differences remained. Our results indicate that the reduction in hippocampal IDex binding in patients with epilepsy is due to a decrease in hippocampal volume rather than to a decrease in receptor concentration.
Y1  - 1997
SN  - 1619-7089
VL  - 24
IS  - 9
SP  - 1156
EP  - 1161
ER  - 
TY  - JOUR
A1  - Langen, Karl J.
A1  - Ziemons, Karl
A1  - Kiwit, Jürgen C. W.
A1  - Herzog, Hans
A1  - Kuwert, Torsten
A1  - Bock, Wolfgang
A1  - Stöcklin, Gerhard
A1  - Feinendegen, Ludwig E.
A1  - Müller-Gärtner, Hans-W.
T1  - 3-[123I]iodo-α-methyltyrosine and [methyl-11C]-L-methionine uptake in cerebral gliomas: a compara-tive study using SPECT and PET
JF  - Journal of Nuclear Medicine
Y1  - 1997
SN  - 0161-5505
VL  - 38
IS  - 4
SP  - 517
EP  - 522
ER  - 
TY  - JOUR
A1  - Grießmeier, M.
A1  - Sonnenberg, F.
A1  - Weckesser, M.
A1  - Ziemons, Karl
A1  - Langen, K.-J.
A1  - Müller-Gärtner, H. W.
T1  - Improvement of SPECT quantification in small brain structures by using experiment based recovery-coefficient corrections
JF  - European Journal of Nuclear Medicine
Y1  - 1996
SN  - 1619-7089
N1  - Abstracts ; PSu827
VL  - 23
IS  - 9
SP  - 1238
EP  - 1238
ER  - 
TY  - JOUR
A1  - Boecker, Henning
A1  - Kuwert, Torsten
A1  - Langen, Karl-J.
A1  - Lange, Herwig W.
A1  - Czech, Norbert
A1  - Ziemons, Karl
A1  - Herzog, Hans
A1  - Shikare, Shekar
A1  - Weindl, Anton
A1  - Feinendegen, Ludwig E.
T1  - SPECT with HMPAO compared to PET with FDG in Huntington disease
JF  - Journal of Computer Assisted Tomography
Y1  - 1994
SN  - 1532-3145
VL  - 18
IS  - 4
SP  - 542
EP  - 548
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
T1  - A measurement of the ratio of the nucleon structure function in copper and deuterium
JF  - Zeitschrift für Physik C Particles and Fields
N2  - Results are presented on the ratios of the nucleon structure function in copper to deuterium from two separate experiments. The data confirm that the nucleon structure function,F 2, is different for bound nucleons than for the quasi-free ones in the deuteron. The redistribution in the fraction of the nucleon's momentum carried by quarks is investigated and it is found that the data are compatible with no integral loss of quark momenta due to nuclear effects.
Y1  - 1993
SN  - 1431-5858
N1  - European Muon Collaboration
VL  - 57
IS  - 2
SP  - 211
EP  - 218
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
A1  - Herzog, H.
A1  - Bosetti, P.
A1  - Feinendegen, L. E.
T1  - Iterative image reconstruction with weighted pixel contribution to projection elements
JF  - European Journal of Nuclear Medicine
Y1  - 1992
SN  - 1619-7089
N1  - Abstracts of the European Association of Nuclear Medicine Congress 23–26 August 1992 Lisboa, Portugal ; V143-2
VL  - 19
IS  - 8
SP  - 588
EP  - 588
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
T1  - Muoproduction of J/ψ and the gluon distribution of the nucleon
JF  - Zeitschrift für Physik C Particles and Fields
N2  - Measurements are presented of the inclusive distributions of the J/Ψ meson produced by muons of energy 200 GeV from an ammonia target. The gluon distribution of the nucleon has been derived from the data in the range 0.04<x<0.36 using a technique based on the colour singlet model. An arbitrary normalisation factor is required to obtain a reasonable integral of the gluon distribution. Some comments are made on the use of J/Ψ productionby virtual photons to extract the gluon distribution at HERA.
Y1  - 1992
SN  - 1431-5858
N1  - European Muon Collaboration
VL  - 56
IS  - 1
SP  - 21
EP  - 28
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
T1  - Comparison of forward hadrons produced in muon interactions on nuclear targets and deuterium
JF  - Zeitschrift für Physik C Particles and Fields
N2  - Differential multiplicities of forward produced hadrons in deep inelastic muon scattering on nuclear targets have been compared with those from deuterium. The ratios are observed to increase towards unity as the virtual photon energy increases with no significant dependence on the other muon kinematic variables. The hadron transverse momentum distribution is observed to be broadened in nuclear targets. The dependence on the remaining hadron variables is investigated and the results are discussed in the framework of intranuclear interaction models and in the context of the EMC effect.
Y1  - 1991
SN  - 1431-5858
N1  - European Muon Collaboration
VL  - 52
IS  - 1
SP  - 1
EP  - 11
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
A1  - Herzog, H.
A1  - Feinendegen, L. E.
T1  - Iterative image reconstruction with weighted pixel contribution to projection element
JF  - European Journal of Nuclear Medicine
Y1  - 1990
SN  - 1619-7089
N1  - Abstracts of the European Association of Nuclear Medicine Congress ; V52
VL  - 16
IS  - 7
SP  - 403
EP  - 403
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
T1  - An investigation of the spin structure of the proton in deep inelastic scattering of polarised muons and polarised protons
JF  - Nuclear Physics B
N2  - The spin asymmetry in deep inelastic scattering of longitudinally polarised muons by longitudinally polarised protons has been measured in the range 0.01<×<0.7. The spin dependent structure function g1(x) for the proton has been determined and, combining the data with earlier SLAC measurements, its integral over x found to be 0.126±0.010(stat.)±0.015(syst.), in disagreement with the Ellis-Jaffe sum rule. Assuming the validity of the Biorken sum rule, this result implies a significant negative value for the integral of g1 for the neutron. These integrals lead to the conclusion, in the naïve quark parton model, that the total quark spin constitutes a rather small fraction of the spin of the nucleon. Results are also presented on the asymmetries in inclusive hadron production which are consistent with the above picture.
Y1  - 1989
SN  - 0550-3213
N1  - European Muon Collaboration
VL  - 328
IS  - 1
SP  - 1
EP  - 35
ER  - 
TY  - JOUR
A1  - Berghoff, G.
A1  - Lanske, D.
A1  - Schultze, K.
A1  - Ziemons, Karl
T1  - Jets and QCD-effects in muon-nuclean scattering
JF  - Verhandlungen der Deutschen Physikalischen Gesellschaft
Y1  - 1988
SN  - 0420-0195
VL  - 23
IS  - 5
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
T1  - A measurement of the spin asymmetry of the structure function g1 in deep inelastic muon-proton scattering
JF  - Physics Letters B
N2  - The spin asymmetry in deep inelastic scattering of longitudinally polarised muons by longitudinally polarised protons has been measured over a large x range (0.01<x<0.7). The spin-dependent structure function g1(x) for the proton has been determined and its integral over x found to be 0.114±0.012±0.026, in disagreement with the Ellis-Jaffe sum rule. Assuming the validity of the Bjorken sum rule, this result implies a significant negative value for the integral of g1 for the neutron. These values for the integrals of g1 lead to the conclusion that the total quark spin constitutes a rather small fraction of the spin of the nucleon.
Y1  - 1988
SN  - 0370-2693
N1  - European Muon Collaboration
VL  - 206
IS  - 2
SP  - 364
EP  - 370
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
A1  - Berghoff, G.
A1  - Lanske, D.
A1  - Schultze, K.
T1  - Strangeness production in deep inelastic muon-nucleon scattering
JF  - Verhandlungen der Deutschen Physikalischen Gesellschaft
Y1  - 1988
SN  - 0420-0195
VL  - 23
IS  - 5
SP  - T309
EP  - T309
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
T1  - Jet production and fragmentation properties in deep inelastic muon scattering
JF  - Zeitschrift für Physik C :  Particles and Fields
Y1  - 1987
SN  - 0170-9739
N1  - European Muon Collaboration
VL  - 36
IS  - 4
SP  - 527
EP  - 543
ER  - 
TY  - JOUR
A1  - Heierli, Joachim
A1  - Purves, Ross S.
A1  - Felber, Andreas
A1  - Kowalski, Julia
T1  - Verification of nearest-neighbours interpretations in avalanche forecasting
JF  - Annals of Glaciology
N2  - This paper examines the positive and negative aspects of a range of interpretations of nearest-neighbours models. Measures-oriented and distributionoriented verification methods are applied to categorial, probabilistic and descriptive interpretations of nearest neighbours used operationally in avalanche forecasting in Scotland and Switzerland. The dependence of skill and accuracy measures on base rate is illustrated. The purpose of the forecast and the definition of events are important variables in determining the quality of the forecast. A discussion of the application of different interpretations in operational avalanche forecasting is presented.
KW  - avalanche
Y1  - 2004
SN  - 1727-5644
VL  - 38
IS  - 1
SP  - 84
EP  - 88
ER  - 
TY  - JOUR
A1  - McArdell, Brian W.
A1  - Bartelt, Perry
A1  - Kowalski, Julia
T1  - Field observations of basal forces and fluid pore pressure in a debris flow
JF  - Geophysical Research Letters (GRL)
N2  - Using results from an 8 m2 instrumented force plate we describe field measurements of normal and shear stresses, and fluid pore pressure for a debris flow. The flow depth increased from 0.1 to 1 m within the first 12 s of flow front arrival, remained relatively constant until 100 s, and then gradually decreased to 0.5 m by 600 s. Normal and shear stresses and pore fluid pressure varied in-phase with the flow depth. Calculated bulk densities are ρb = 2000–2250 kg m−3 for the bulk flow and ρf = 1600–1750 kg m−3 for the fluid phase. The ratio of effective normal stress to shear stress yields a Coulomb basal friction angle of ϕ = 26° at the flow front. We did not find a strong correlation between the degree of agitation in the flow, estimated using the signal from a geophone on the force plate, and an assumed dynamic pore fluid pressure. Our data support the idea that excess pore-fluid pressures are long lived in debris flows and therefore contribute to their unusual mobility.
KW  - debris flow
Y1  - 2007
SN  - 0094-8276
VL  - 34
IS  - 7
ER  - 
TY  - JOUR
A1  - Fischer, Jan-Thomas
A1  - Kowalski, Julia
A1  - Pudasaini, Shiva P.
A1  - Miller, S. A.
T1  - Dynamic Avalanche Modeling in Natural Terrain
JF  - International Snow Science Workshop, Davos 2009, Proceedings ; Proc. ISSW 2009
N2  - The powerful avalanche simulation toolbox RAMMS (Rapid Mass Movements) is based on a depth-averaged
hydrodynamic system of equations with a Voellmy-Salm friction relation. The two empirical friction parameters
μ and �  correspond to a dry Coulomb friction and a viscous resistance, respectively. Although μ and � lack a
proper physical explanation, 60 years of acquired avalanche data in the Swiss Alps made a systematic calibration
possible. RAMMS can therefore successfully model avalanche flow depth, velocities, impact pressure and run
out distances. Pudasaini and Hutter (2003) have proposed extended, rigorously derived model equations that
account for local curvature and twist. A coordinate transformation into a reference system, applied to the actual
mountain topography of the natural avalanche path, is performed. The local curvature and the twist of the
avalanche path induce an additional term in the overburden pressure. This leads to a modification of the Coulomb
friction, the free-surface pressure gradient, the pressure induced by the channel, and the gravity components
along and normal to the curved and twisted reference surface. This eventually guides the flow dynamics and
deposits of avalanches. In the present study, we investigate the influence of curvature on avalanche flow in
real mountain terrain. Simulations of real avalanche paths are performed and compared for the different models
approaches. An algorithm to calculate curvature in real terrain is introduced in RAMMS. This leads to a curvature
dependent friction relation in an extended version of the Voellmy-Salm model equations. Our analysis provides
yet another step in interpreting the physical meaning and significance of the friction parameters used in the
RAMMS computational environment.
KW  - snow
KW  - avalanche
Y1  - 2009
SP  - 448
EP  - 452
ER  - 
TY  - JOUR
A1  - Christen, Marc
A1  - Kowalski, Julia
A1  - Bartelt, Perry
T1  - RAMMS: Numerical simulation of dense snow avalanches in three-dimensional terrain
JF  - Cold Regions Science and Technology
N2  - Numerical avalanche dynamics models have become an essential part of snow engineering. Coupled with field observations and historical records, they are especially helpful in understanding avalanche flow in complex terrain. However, their application poses several new challenges to avalanche engineers. A detailed understanding of the avalanche phenomena is required to construct hazard scenarios which involve the careful specification of initial conditions (release zone location and dimensions) and definition of appropriate friction parameters. The interpretation of simulation results requires an understanding of the numerical solution schemes and easy to use visualization tools. We discuss these problems by presenting the computer model RAMMS, which was specially designed by the SLF as a practical tool for avalanche engineers. RAMMS solves the depth-averaged equations governing avalanche flow with accurate second-order numerical solution schemes. The model allows the specification of multiple release zones in three-dimensional terrain. Snow cover entrainment is considered. Furthermore, two different flow rheologies can be applied: the standard Voellmy–Salm (VS) approach or a random kinetic energy (RKE) model, which accounts for the random motion and inelastic interaction between snow granules. We present the governing differential equations, highlight some of the input and output features of RAMMS and then apply the models with entrainment to simulate two well-documented avalanche events recorded at the Vallée de la Sionne test site.
KW  - RAMMS
KW  - snow
KW  - avalanche
Y1  - 2010
U6  - https://doi.org/10.1016/j.coldregions.2010.04.005
SN  - 1872-7441
VL  - 63
IS  - 1-2
SP  - 1
EP  - 14
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Christen, Marc
A1  - Bartelt, Perry
A1  - Kowalski, Julia
T1  - Back calculation of the In den Arelen avalanche with RAMMS: Interpretation of model results
JF  - Annals of Glaciology
N2  - Two- and three-dimensional avalanche dynamics models are being increasingly used in hazard-mitigation studies. These models can provide improved and more accurate results for hazard mapping than the simple one-dimensional models presently used in practice. However, two- and three-dimensional models generate an extensive amount of output data, making the interpretation of simulation results more difficult. To perform a simulation in three-dimensional terrain, numerical models require a digital elevation model, specification of avalanche release areas (spatial extent and volume), selection of solution methods, finding an adequate calculation resolution and, finally, the choice of friction parameters. In this paper, the importance and difficulty of correctly setting up and analysing the results of a numerical avalanche dynamics simulation is discussed. We apply the two-dimensional simulation program RAMMS to the 1968 extreme avalanche event In den Arelen. We show the effect of model input variations on simulation results and the dangers and complexities in their interpretation.
KW  - avalanche
Y1  - 2010
SN  - 1727-5644
U6  - https://doi.org/10.3189/172756410791386553
VL  - 51
IS  - 54
SP  - 161
EP  - 168
PB  - Cambridge University Press
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Bühler, Yves
A1  - Christen, Marc
A1  - Kowalski, Julia
A1  - Bartelt, Perry
T1  - Sensitivity of snow avalanche simulations to digital elevation model quality and resolution
JF  - Annals of Glaciology
N2  - Digital elevation models (DEMs), represent the three-dimensional terrain and are the basic input for numerical snow avalanche dynamics simulations. DEMs can be acquired using topographic maps or remote-sensing technologies, such as photogrammetry or lidar. Depending on the acquisition technique, different spatial resolutions and qualities are achieved. However, there is a lack of studies that investigate the sensitivity of snow avalanche simulation algorithms to the quality and resolution of DEMs. Here, we perform calculations using the numerical avalance dynamics model RAMMS, varying the quality and spatial resolution of the underlying DEMs, while holding the simulation parameters constant. We study both channelized and open-terrain avalanche tracks with variable roughness. To quantify the variance of these simulations, we use well-documented large-scale avalanche events from Davos, Switzerland (winter 2007/08), and from our large-scale avalanche test site, Valĺee de la Sionne (winter 2005/06). We find that the DEM resolution and quality is critical for modeled flow paths, run-out distances, deposits, velocities and impact pressures. Although a spatial resolution of ~25 m is sufficient for large-scale avalanche modeling, the DEM datasets must be checked carefully for anomalies and artifacts before using them for dynamics calculations.
KW  - snow
KW  - avalanche
Y1  - 2011
SN  - 1727-5644
VL  - 52
IS  - 58
SP  - 72
EP  - 80
PB  - Cambridge University Press
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Fischer, Jan-Thomas
A1  - Kowalski, Julia
A1  - Pudasaini, Shiva P.
T1  - Topographic curvature effects in applied avalanche modelling
JF  - Cold Regions Science and Technology
N2  - This paper describes the implementation of topographic curvature effects within the RApid Mass MovementS (RAMMS) snow avalanche simulation toolbox. RAMMS is based on a model similar to shallow water equations with a Coulomb friction relation and the velocity dependent Voellmy drag. It is used for snow avalanche risk assessment in Switzerland. The snow avalanche simulation relies on back calculation of observed avalanches. The calibration of the friction parameters depends on characteristics of the avalanche track. The topographic curvature terms are not yet included in the above mentioned classical model. Here, we fundamentally improve this model by mathematically and physically including the topographic curvature effects. By decomposing the velocity dependent friction into a topography dependent term that accounts for a curvature enhancement in the Coulomb friction, and a topography independent contribution similar to the classical Voellmy drag, we construct a general curvature dependent frictional resistance, and thus propose new extended model equations. With three site-specific examples, we compare the apparent frictional resistance of the new approach, which includes topographic curvature effects, to the classical one. Our simulation results demonstrate substantial effects of the curvature on the flow dynamics e.g., the dynamic pressure distribution along the slope. The comparison of resistance coefficients between the two models demonstrates that the physically based extension presents an improvement to the classical approach. Furthermore a practical example highlights its influence on the pressure outline in the run out zone of the avalanche. Snow avalanche dynamics modeling natural terrain curvature centrifugal force friction coefficients.
KW  - Snow
KW  - Avalanche
Y1  - 2012
U6  - https://doi.org/10.1016/j.coldregions.2012.01.005
SN  - 1872-7441
VL  - 74-75
SP  - 21
EP  - 30
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Kirchner, Patrick
A1  - Oberländer, Jan
A1  - Suco, Henri-Pierre
A1  - Rysstad, Gunnar
A1  - Schöning, Michael Josef
T1  - Monitoring the microbicidal effectiveness of gaseous hydrogen peroxide in sterilisation processes by means of a calorimetric gas sensor
JF  - Food control
N2  - In the present work, a novel method for monitoring sterilisation processes with gaseous H2O2 in combination with heat activation by means of a specially designed calorimetric gas sensor was evaluated. Therefore, the sterilisation process was extensively studied by using test specimens inoculated with Bacillus atrophaeus spores in order to identify the most influencing process factors on its microbicidal effectiveness. Besides the contact time of the test specimens with gaseous H2O2 varied between 0.2 and 0.5 s, the present H2O2 concentration in a range from 0 to 8% v/v (volume percent) had a strong influence on the microbicidal effectiveness, whereas the change of the vaporiser temperature, gas flow and humidity were almost negligible. Furthermore, a calorimetric H2O2 gas sensor was characterised in the sterilisation process with gaseous H2O2 in a wide range of parameter settings, wherein the measurement signal has shown a linear response against the H2O2 concentration with a sensitivity of 4.75 °C/(% v/v). In a final step, a correlation model by matching the measurement signal of the gas sensor with the microbial inactivation kinetics was established that demonstrates its suitability as an efficient method for validating the microbicidal effectiveness of sterilisation processes with gaseous H2O2.
KW  - hydrogen peroxide
KW  - sterilisation
KW  - Bacillus atrophaeus
KW  - calorimetric gas sensor
Y1  - 2012
U6  - https://doi.org/10.1016/j.foodcont.2012.11.048
SN  - 0956-7135
VL  - 31
IS  - 2
SP  - 530
EP  - 538
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Olaru, Alexandra Maria
A1  - Kowalski, Julia
A1  - Sethi, Vaishali
A1  - Blümich, Bernhard
T1  - Exchange relaxometry of flow at small Péclet numbers in a glass bead pack
JF  - Journal of Magnetic Resonance (JMR)
N2  - In this paper we consider low Péclet number flow in bead packs. A series of relaxation exchange experiments has been conducted and evaluated by ILT analysis. In the resulting correlation maps, we observed a collapse of the signal and a translation towards smaller relaxation times with increasing flow rates, as well as a signal tilt with respect to the diagonal. In the discussion of the phenomena we present a mathematical theory for relaxation exchange experiments that considers both diffusive and advective transport. We perform simulations based on this theory and discuss them with respect to the conducted experiments.
KW  - NMR exchange relaxometry
KW  - Low-field NMR
Y1  - 2012
U6  - https://doi.org/10.1016/j.jmr.2012.04.015
SN  - 1096-0856
VL  - 220
SP  - 32
EP  - 44
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Kowalski, Julia
A1  - McElwaine, Jim N.
T1  - Shallow two-component gravity-driven flows with vertical variation
JF  - Journal of Fluid Mechanics
Y1  - 2013
SN  - 0022-1120
VL  - 714
SP  - 434
EP  - 462
PB  - Cambridge Univ. Press
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Bassam, Rasha
A1  - Digel, Ilya
A1  - Hescheler, Jürgen
A1  - Temiz Artmann, Aysegül
A1  - Artmann, Gerhard
T1  - Effects of spermine NONOate and ATP on protein aggregation: light scattering evidences
JF  - BMC Biophysics
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?10.1186/2046-1682-6-1
SN  - 2046-1682
SP  - 1
EP  - 14
PB  - BioMed Central
CY  - London
ER  - 
TY  - JOUR
A1  - Hasan, Istabrak
A1  - Keil, Ludger
A1  - Staat, Manfred
A1  - Wahl, Gerhard
A1  - Bourauel, Christoph
T1  - Determination of the frictional coefficient of the implant-antler interface : experimental approach
JF  - Biomedical Engineering / Biomedizinische Technik
N2  - The similar bone structure of reindeer antler to human bone permits studying the osseointegration of dental implants in the jawbone. As the friction is one of the major factors that have a significant influence on the initial stability of immediately loaded dental implants, it is essential to define the frictional coefficient of the implant-antler interface. In this study, the kinetic frictional forces at the implant-antler interface were measured experimentally using an optomechanical setup and a stepping motor controller under different axial loads and sliding velocities. The corresponding mean values of the static and kinetic frictional coefficients were within the range of 0.5–0.7 and 0.3–0.5, respectively. An increase in the frictional forces with increasing applied axial loads was registered. The measurements showed an evidence of a decrease in the magnitude of the frictional coefficient with increasing sliding velocity. The results of this study provide a considerable assessment to clarify the suitable frictional coefficient to be used in the finite element contact analysis of antler specimens.
Y1  - 2012
SN  - 1862-278X
VL  - 57
IS  - 5
SP  - 359
EP  - 363
PB  - De Gruyter
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Pieper, Martin
T1  - Multiobjective optimization with expensive objectives applied to a thermodynamic material design problem
JF  - Proceedings in applied mathematics and mechanics : PAMM. 11 (2011), H. 1
Y1  - 2011
SN  - 1617-7061
SP  - 733
EP  - 734
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Fateri, Miranda
A1  - Hötter, Jan-Steffen
A1  - Gebhardt, Andreas
T1  - Experimental and Theoretical Investigation of Buckling Deformation of Fabricated Objects by Selective Laser Melting
JF  - Physics Procedia
N2  - Although Selective Laser Melting (SLM) process is an innovative manufacturing method, there are challenges such as inferior mechanical properties of fabricated objects. Regarding this, buckling deformation which is caused by thermal stress is one of the undesired mechanical properties which must be alleviated. As buckling deformation is more observable in hard to process materials, silver is selected to be studied theoretically and experimentally for this paper. Different scanning strategies are utilized and a Finite Element Method (FEM) is applied to calculate the temperature gradient in order to determine its effect on the buckling deformation of the objects from experiments.
Y1  - 2012
U6  - https://doi.org/10.1016/j.phpro.2012.10.062
SN  - 1875-3892
N1  - Part of special issue "Laser Assisted Net shape Engineering 7 (LANE 2012)"
VL  - 39
SP  - 464
EP  - 470
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Werner, Frederik
A1  - Takenaga, Shoko
A1  - Taki, Hidenori
A1  - Sawada, Kazuaki
A1  - Schöning, Michael Josef
T1  - Comparison of label-free ACh-imaging sensors based on CCD and LAPS
JF  - Sensors and  Actuators B: Chemical (2012)
N2  - Semiconductor-based chemical imaging sensors, like the light-addressable potentiometric sensor (LAPS) or the pH-imaging sensor based on a charge-coupled device (CCD), are becoming a powerful tool for label-free imaging of biological phenomena. We have proposed a polyion-based enzymatic membrane to develop an acetylcholine (ACh) imaging sensor for neural cell-activity observations. In this study, a CCD-type ACh-imaging sensor and a LAPS-type ACh-imaging sensor were fabricated and the prospect of both sensors was clarified by making a comparison of their basic characteristics.
Y1  - 2013
SN  - 0925-4005
VL  - 177
SP  - 745
EP  - 752
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Pieper, Martin
T1  - Nonlinear integral equations for an inverse electromagnetic scattering problem
JF  - Journal of Physics Conference Series. 124 (2008)
Y1  - 2008
SN  - 1742-6596
ER  - 
TY  - JOUR
A1  - Pieper, Martin
A1  - Ivanyshyn, Olha
T1  - Nonlinear integral equations for a 3D inverse acoustic scattering problem : abstract / O. Ivanyshyn and M. Pieper
Y1  - 2008
N1  - World Congress on Computational Mechanics <8, 2008, Venedig> ; European Congress on Computational Methods in Applied Sciences and Engineering <5, 2008, Venedig>
ER  - 
TY  - JOUR
A1  - Ewe, Hendrik
A1  - Klein, Peter
A1  - Pieper, Martin
A1  - Füldner, G.
T1  - Heat conductivity in sintered aluminium fibers
JF  - Cellular metals for structural and functional applications : CELLMET 2008 ; proceedings of the International Symposium on Cellular Metals for Structural and Functional Applications held October 8 - 10, 2008 in Dresden, Germany / ed. by Günter Stephani
Y1  - 2009
SP  - 187
EP  - 193
PB  - Fraunhofer IFAM
CY  - Dresden
ER  - 
TY  - JOUR
A1  - Pieper, Martin
A1  - Klein, Peter
T1  - A simple and accurate numerical network flow model for bionic micro heat exchangers
JF  - Heat mass transfer
Y1  - 2011
SN  - 0947-7411
VL  - 47
IS  - 5
SP  - 491
EP  - 503
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Pieper, Martin
A1  - Klein, Peter
T1  - Application of simple, periodic homogenization techniques to non-linear heat conduction problems in non-periodic, porous media
JF  - Heat mass transfer
N2  - Often, detailed simulations of heat conduction in complicated, porous media have large runtimes. Then homogenization is a powerful tool to speed up the calculations by preserving accurate solutions at the same time. Unfortunately real structures are generally non-periodic, which requires unpractical, complicated homogenization techniques. We demonstrate in this paper, that the application of simple, periodic techniques to realistic media, that are just close to periodic, gives accurate, approximative solutions. In order to obtain effective parameters for the homogenized heat equation, we have to solve a so called “cell problem”. In contrast to periodic structures it is not trivial to determine a suitable unit cell, which represents a non-periodic media. To overcome this problem, we give a rule of thumb on how to choose a good cell. Finally we demonstrate the efficiency of our method for virtually generated foams as well as real foams and compare these results to periodic structures.
Y1  - 2012
U6  - https://doi.org/10.1007/s00231-011-0879-4
SN  - 0947-7411
VL  - 48
IS  - 2
SP  - 291
EP  - 300
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Pieper, Martin
A1  - Klein, Peter
T1  - Numerical solution of the heat equation with non-linear, time derivative-dependent source term
JF  - International Journal for Numerical Methods in Engineering
N2  - The mathematical modeling of heat conduction with adsorption effects in coated metal structures yields the heat equation with piecewise smooth coefficients and a new kind of source term. This term is special, because it is non-linear and furthermore depends on a time derivative. In our approach we reformulated this as a new problem for the usual heat equation, without source term but with a new non-linear coefficient. We gave an existence and uniqueness proof for the weak solution of the reformulated problem. To obtain a numerical solution, we developed a semi-implicit and a fully implicit finite volume method. We compared these two methods theoretically as well as numerically. Finally, as practical application, we simulated the heat conduction in coated aluminum fibers with adsorption in the zeolite coating. Copyright © 2010 John Wiley & Sons, Ltd.
Y1  - 2010
U6  - https://doi.org/10.1002/nme.2937
SN  - 0029-5981
VL  - 84
IS  - 10
SP  - 1205
EP  - 1221
PB  - Wiley
CY  - Chichester
ER  - 
TY  - JOUR
A1  - Pieper, Martin
T1  - Vector hyperinterpolation on the sphere
JF  - Journal of approximation theory. 156 (2009), H. 2
Y1  - 2009
SN  - 0021-9045
SP  - 173
EP  - 186
ER  - 
TY  - JOUR
A1  - Poghossian, Arshak
A1  - Weil, M. H.
A1  - Bäcker, Matthias
A1  - Mayer, D.
A1  - Schöning, Michael Josef
T1  - Field-effect Devices Functionalised with Gold-Nanoparticle/Macromolecule Hybrids: New Opportunities for a Label-Free Biosensing
JF  - Procedia Engineering
N2  - Field-effect capacitive electrolyte-insulator-semiconductor (EIS) sensors functionalised with citrate-capped gold nanoparticles (AuNP) have been used for the electrostatic detection of macromolecules by their intrinsic molecular charge. The EIS sensor detects the charge changes in the AuNP/macromolecule hybrids induced by the adsorption or binding events. A feasibility of the proposed detection scheme has been exemplary demonstrated by realising EIS sensors for the detection of poly-D-lysine molecules.
Y1  - 2012
U6  - https://doi.org/10.1016/j.proeng.2012.09.136
SN  - 1877-7058
N1  - Part of special issue "26th European Conference on Solid-State Transducers, EUROSENSOR 2012"
IS  - 47
SP  - 273
EP  - 276
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Miyamoto, K.
A1  - Ichimura, H.
A1  - Wagner, Torsten
A1  - Yoshinobu, T.
A1  - Schöning, Michael Josef
T1  - Chemical Imaging of ion Diffusion in a Microfluidic Channel
JF  - Procedia Engineering
N2  - The chemical imaging sensor is a chemical sensor which is capable of visualizing the spatial distribution of chemical species in sample solution. In this study, a novel measurement system based on the chemical imaging sensor was developed to observe the inside of a Y-shaped microfluidic channel while injecting two sample solutions from two branches. From the collected chemical images, it was clearly observed that the injected solutions formed laminar flows in the microfluidic channel. In addition, ion diffusion across the laminar flows was observed. This label-free method can acquire quantitative data of ion distribution and diffusion in microfluidic devices, which can be used to determine the diffusion coefficients, and therefore, the molecular weights of chemical species in the sample solution.
Y1  - 2012
U6  - https://doi.org/10.1016/j.proeng.2012.09.289
SN  - 1877-7058
N1  - Part of special issue "26th European Conference on Solid-State Transducers, EUROSENSOR 2012"
IS  - 47
SP  - 886
EP  - 889
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Wagner, Torsten
A1  - Shigiahara, N.
A1  - Miyamoto, K.
A1  - Suzurikawa, J.
A1  - Finger, F.
A1  - Schöning, Michael Josef
A1  - Yoshinobu, T.
T1  - Light-addressable Potentiometric Sensors and Light–addressable Electrodes as a Combined Sensor-and-manipulator Microsystem with High Flexibility
JF  - Procedia Engineering
N2  - This work describes the novel combination of the light-addressable electrode (LAE) and the light-addressable potentiometric sensor (LAPS) into a microsystem set-up. Both the LAE as well as the LAPS shares the principle of addressing the active spot by means of a light beam. This enables both systems to manipulate resp. to detect an analyte with a high spatial resolution. Hence, combining both principles into a single set-up enables the active stimulation e.g., by means of electrolysis and a simultaneous observation e.g., the response of an entrapped biological cell by detection of extracellular pH changes. The work will describe the principles of both technologies and the necessary steps to integrate them into a single set-up. Furthermore, examples of application and operation of such systems will be presented.
Y1  - 2012
U6  - https://doi.org/10.1016/j.proeng.2012.09.290
SN  - 1877-7058
N1  - Part of special issue "26th European Conference on Solid-State Transducers, EUROSENSOR 2012"
IS  - 47
SP  - 890
EP  - 893
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Iken, Heiko
A1  - Kirsanov, D.
A1  - Legin, A.
A1  - Schöning, Michael Josef
T1  - Novel Thin-Film Polymeric Materials for the Detection of Heavy Metals
JF  - Procedia Engineering
N2  - A variety of transition metals, e.g., copper, zinc, cadmium, lead, etc. are widely used in industry as components for wires, coatings, alloys, batteries, paints and so on. The inevitable presence of transition metals in industrial processes implies the ambition of developing a proper analytical technique for their adequate monitoring. Most of these elements, especially lead and cadmium, are acutely toxic for biological organisms. Quantitative determination of these metals at low activity levels in different environmental and industrial samples is therefore a vital task. A promising approach to achieve an at-side or on-line monitoring on a miniaturized and cost efficient way is the combination of a common potentiometric sensor array with heavy metal-sensitive thin-film materials, like chalcogenide glasses and polymeric materials, respectively.
Y1  - 2012
U6  - https://doi.org/10.1016/j.proeng.2012.09.148
SN  - 1877-7058
N1  - Part of special issue "26th European Conference on Solid-State Transducers, EUROSENSOR 2012"
IS  - 47
SP  - 322
EP  - 325
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Digel, Ilya
A1  - Zhubanova, Azhar A.
A1  - Nojima, H.
A1  - Artmann, Gerhard
T1  - The use of bactericidal effects of cluster ions generated by plasma in medical biotechnology
JF  - Biotechnologija : teorija i praktika (2004)
Y1  - 2004
SN  - 1028-9399
SP  - 46
EP  - 52
ER  - 
TY  - JOUR
A1  - Tran, Thanh Ngoc
A1  - Staat, Manfred
T1  - An Edge-Based Smoothed Finite Element Method for Primal-Dual Shakedown Analysis of Structures Under Uncertainties
JF  - Limit State of Materials and Structures : Direct Methods 2. Saxcé, Géry de (Hrsg.)
Y1  - 2013
SN  - 978-94-007-5424-9
SP  - 89
EP  - 102
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Weigand, Christoph
T1  - Statistical Tests Based on Reliability and Precision
JF  - Economic Quality Control : EQC ; international journal for quality and reliability
N2  - The construction of a statistical test is investigated which is based only on “reliability” and “precision” as quality criteria. The reliability of a statistical test is quantifiedin a straightforward way by the probability that the decision of the test is correct.  However, the quantification of the precision of a statistical test is not at all evident.  Thereforethe paper presents and discusses several approaches.  Moreover the distinction of “nullhypothesis” and “alternative hypothesis” is not necessary any longer.
Y1  - 2012
U6  - https://doi.org/10.1515/eqc-2012-0002
SN  - 1869-6147
VL  - 27
IS  - 1
SP  - 43
EP  - 64
PB  - De Gruyter
CY  - Berlin
ER  -