@article{YazdanbakhshSolbachBitz2012, author = {Yazdanbakhsh, Pedram and Solbach, Klaus and Bitz, Andreas}, title = {Variable power combiner for RF mode shimming in 7-T MR imaging}, series = {IEEE Transaction on Biomedical Engineering}, volume = {59}, journal = {IEEE Transaction on Biomedical Engineering}, number = {9}, publisher = {IEEE}, address = {New York}, issn = {1558-2531}, doi = {10.1109/TBME.2012.2205926}, pages = {2549 -- 2557}, year = {2012}, abstract = {This contribution discusses the utilization of RF power in an MRI system with RF mode shimming which enables the superposition of circularly polarized modes of a transmit RF coil array driven by a Butler matrix. Since the required power for the individual modes can vary widely, mode-shimming can result in a significant underutilization of the total available RF power. A variable power combiner (VPC) is proposed to improve the power utilization: it can be realized as a reconfiguration of the MRI transmit system by the inclusion of one additional matrix network which receives the power from all transmit amplifiers at its input ports and provides any desired (combined) power distribution at its output ports by controlling the phase and amplitude of the amplifiers' input signals. The power distribution at the output ports of the VPC is then fed into the "mode" ports of the coil array Butler matrix in order to superimpose the spatial modes at the highest achievable power utilization. The VPC configuration is compared to the standard configuration of the transmit chain of our MRI system with 8 transmit channels and 16 coils. In realistic scenarios, improved power utilization was achieved from 17\% to 60\% and from 14\% to 55\% for an elliptical phantom and a region of interest in the abdomen, respectively, and an increase of the power utilization of 1 dB for a region of interest in the upper leg. In general, it is found that the VPC allows significant improvement in power utilization when the shimming solution demands only a few modes to be energized, while the technique can yield loss in power utilization in cases with many modes required at high power level.}, language = {en} } @article{ArtmannTeitelSchmidSchoenbein1987, author = {Artmann, Gerhard and Teitel, P. and Schmid-Sch{\"o}nbein, H.}, title = {Variable rheologische Antwort der Erythrozyten auf den Einfluß von Xantinderivaten (Coffein): Experimentelle Differenzierung von "Responders" und "Nonresponders"}, series = {11. Jahrestagung der Gesellschaft f{\"u}r Mikrozirkulation}, journal = {11. Jahrestagung der Gesellschaft f{\"u}r Mikrozirkulation}, publisher = {Karger [u.a.]}, address = {Basel [u.a.]}, pages = {100 -- 105}, year = {1987}, language = {de} } @article{EschGoebelPischinger1995, author = {Esch, Thomas and G{\"o}bel, T. and Pischinger, M.}, title = {Variable Ventilsteuerung - Luft- und Kraftstoffzumessung bei Ottomotoren mit variabler Ventilsteuerung}, series = {Forschungsberichte Verbrennungskraftmaschinen. 578 (1995)}, journal = {Forschungsberichte Verbrennungskraftmaschinen. 578 (1995)}, pages = {1 -- 42}, year = {1995}, language = {de} } @article{EschWoltersSalberetal.2001, author = {Esch, Thomas and Wolters, P. and Salber, W. and Geiger, J.}, title = {Variable Ventilsteuerung und Direkteinspritzung - vom Wettbewerb zur Synergie}, series = {Motor und Umwelt 2001, Internal Combustion Engine Versus Fuel Cell - Potential and Limitations as Automotive Power Sources, Verbrennungsmotor versus Brennstoffzelle - Potenziale und Grenzen f{\"u}r den Automobilantrieb, Proc., Graz, AT, 6.-7. Sep, 2001}, journal = {Motor und Umwelt 2001, Internal Combustion Engine Versus Fuel Cell - Potential and Limitations as Automotive Power Sources, Verbrennungsmotor versus Brennstoffzelle - Potenziale und Grenzen f{\"u}r den Automobilantrieb, Proc., Graz, AT, 6.-7. Sep, 2001}, pages = {183 -- 206}, year = {2001}, language = {de} } @article{KotliarLanzl2018, author = {Kotliar, Konstantin and Lanzl, Ines}, title = {Vaskul{\"a}re Biomarker der retinalen Gef{\"a}βanalyse}, series = {Klinische Monatsbl{\"a}tter fur Augenheilkunde}, volume = {235}, journal = {Klinische Monatsbl{\"a}tter fur Augenheilkunde}, number = {12}, publisher = {Thieme}, address = {Stuttgart}, issn = {0023-2165}, doi = {10.1055/a-0774-7987}, pages = {1352 -- 1359}, year = {2018}, abstract = {Mit modernen nicht invasiven bildgebenden Verfahren lassen sich anhand der Fundusfotografie bzw. der optischen Verfilmung Aspekte der funktionellen und strukturellen retinalen Gef{\"a}ßver{\"a}nderungen objektiv untersuchen. Der Zustand und das Verhalten retinaler Gef{\"a}ße beeinflussen im pr{\"a}-, post- und kapillaren Bereich den Blutfluss und str{\"o}mungsbedingte Stoffwechselverh{\"a}ltnisse passiv und aktiv {\"u}ber den Gef{\"a}ßdurchmesser. Retinale Gef{\"a}ße gleichen von Aufbau und Funktion den zerebralen Gef{\"a}ßen und spiegeln den Zustand der Mikrozirkulation wider. Mithilfe von aus den Gef{\"a}ßweiten berechneten Biomarkern soll eine Aussage {\"u}ber die Prognose von systemischen vaskul{\"a}r bedingten Erkrankungen getroffen werden. Die statische retinale Gef{\"a}ßanalyse befasst sich mit der Untersuchung des Zustandes der pr{\"a}- und postkapillaren Gef{\"a}ßdurchmesser der retinalen Mikrozirkulation anhand einer optischen Fundusaufnahme. Bei der dynamischen retinalen Gef{\"a}ßanalyse wird der L{\"a}ngsschnitt eines retinalen Gef{\"a}ßes nicht invasiv funktionell und strukturell {\"u}ber einen Zeitraum vor, w{\"a}hrend und nach einer spezifischen vaskul{\"a}ren Stimulation untersucht. Die genaue Methodologie der Auswertung und die Bezeichnung der Parameter variieren bei unterschiedlichen Ans{\"a}tzen. Mittels retinaler Gef{\"a}ßanalyse wurden bislang mehrere klinische Querschnitts- und Interventionsstudien in der Augenheilkunde und anderen Fachgebieten, inkl. Kardiologie, Neurologie, Neurochirurgie, Nephrologie, Gyn{\"a}kologie, Sportmedizin, Diabetologie, Hypertensiologie usw. durchgef{\"u}hrt. Mit der statischen retinalen Gef{\"a}ßanalyse steht eine kosteng{\"u}nstige, reproduzierbare, nicht invasive Screeningtechnik zur Verf{\"u}gung, um eine prognostische Aussage {\"u}ber die Gef{\"a}ßgesundheit eines individuellen Patienten zu treffen. Die dynamische retinale Gef{\"a}ßanalyse besitzt ein weiteres diagnostisches Anwendungsspektrum als die statische, da sie das Verhalten retinaler Gef{\"a}ße zeitkontinuierlich untersucht. Die Evaluation vaskul{\"a}rer Erkrankungen sowie zerebro- bzw. kardiovaskul{\"a}rer Morbidit{\"a}t und Mortalit{\"a}t mittels mehrerer methodologischer Modalit{\"a}ten retinaler Gef{\"a}ßanalyse mit ihren jeweiligen quantitativen Biomarkern bietet eine zukunftstr{\"a}chtige diagnostische Perspektive. Die interdisziplin{\"a}re klinische Anwendung dieser vaskul{\"a}ren Biomarker gewinnt zunehmend an Bedeutung, sowohl in der Augenheilkunde als auch in anderen Fachgebieten.}, language = {de} } @article{ConzenAlbannaWeissetal.2018, author = {Conzen, Catharina and Albanna, Walid and Weiss, Miriam and K{\"u}rten, David and Vilser, Walthard and Kotliar, Konstantin and Z{\"a}ske, Charlotte and Clusmann, Hans and Schubert, Gerrit Alexander}, title = {Vasoconstriction and Impairment of Neurovascular Coupling after Subarachnoid Hemorrhage: a Descriptive Analysis of Retinal Changes}, series = {Translational Stroke Research}, journal = {Translational Stroke Research}, number = {9}, publisher = {Springer Nature}, address = {Cham}, issn = {1868-601X}, doi = {10.1007/s12975-017-0585-8}, pages = {284 -- 293}, year = {2018}, abstract = {Impaired cerebral autoregulation and neurovascular coupling (NVC) contribute to delayed cerebral ischemia after subarachnoid hemorrhage (SAH). Retinal vessel analysis (RVA) allows non-invasive assessment of vessel dimension and NVC hereby demonstrating a predictive value in the context of various neurovascular diseases. Using RVA as a translational approach, we aimed to assess the retinal vessels in patients with SAH. RVA was performed prospectively in 24 patients with acute SAH (group A: day 5-14), in 11 patients 3 months after ictus (group B: day 90 ± 35), and in 35 age-matched healthy controls (group C). Data was acquired using a Retinal Vessel Analyzer (Imedos Systems UG, Jena) for examination of retinal vessel dimension and NVC using flicker-light excitation. Diameter of retinal vessels—central retinal arteriolar and venular equivalent—was significantly reduced in the acute phase (p < 0.001) with gradual improvement in group B (p < 0.05). Arterial NVC of group A was significantly impaired with diminished dilatation (p < 0.001) and reduced area under the curve (p < 0.01) when compared to group C. Group B showed persistent prolonged latency of arterial dilation (p < 0.05). Venous NVC was significantly delayed after SAH compared to group C (A p < 0.001; B p < 0.05). To our knowledge, this is the first clinical study to document retinal vasoconstriction and impairment of NVC in patients with SAH. Using non-invasive RVA as a translational approach, characteristic patterns of compromise were detected for the arterial and venous compartment of the neurovascular unit in a time-dependent fashion. Recruitment will continue to facilitate a correlation analysis with clinical course and outcome.}, language = {en} } @inproceedings{BlumAlbannaBenninghausetal.2019, author = {Blum, Yannik and Albanna, Walid and Benninghaus, Anne and Kotliar, Konstantin}, title = {Vasomotion in retinal vessels of patients presenting post hemorrhagic hydrocephalus following subarachnoid hemorrhage}, series = {3rd YRA MedTech Symposium 2019 : May 24 / 2019 / FH Aachen}, booktitle = {3rd YRA MedTech Symposium 2019 : May 24 / 2019 / FH Aachen}, editor = {Staat, Manfred and Erni, Daniel}, publisher = {Universit{\"a}t Duisburg-Essen}, address = {Duisburg}, organization = {MedTech Symposium}, isbn = {978-3-940402-22-6}, doi = {10.17185/duepublico/48750}, pages = {38 -- 39}, year = {2019}, abstract = {Clearance of blood components and fluid drainage play a crucial role in subarachnoid hemorrhage (SAH) and post hemorrhagic hydrocephalus (PHH). With the involvement of interstitial fluid (ISF) and cerebrospinal fluid (CSF), two pathways for the clearance of fluid and solutes in the brain are proposed. Starting at the level of capillaries, flow of ISF follows along the basement membranes in the walls of cerebral arteries out of the parenchyma to drain into the lymphatics and CSF [1]-[3]. Conversely, it is shown that CSF enters the parenchyma between glial and pial basement membranes of penetrating arteries [4]-[6]. Nevertheless, the involved structures and the contribution of either flow pathway to fluid balance between the subarachnoid space and interstitial space remains controversial. Low frequency oscillations in vascular tone are referred to as vasomotion and corresponding vasomotion waves are modeled as the driving force for flow of ISF out of the parenchyma [7]. Retinal vessel analysis (RVA) allows non-invasive measurement of retinal vessel vasomotion with respect to diameter changes [8]. Thus, the aim of the study is to investigate vasomotion in RVA signals of SAH and PHH patients.}, language = {en} } @article{GiresiniSassuButenwegetal.2017, author = {Giresini, Linda and Sassu, Mauro and Butenweg, Christoph and Alecci, Valerio and De Stefano, Mario}, title = {Vault macro-element with equivalent trusses in global seismic analyses}, series = {Earthquakes and Structures}, volume = {12}, journal = {Earthquakes and Structures}, number = {4}, publisher = {Techno-Press}, address = {Taejŏn}, issn = {2092-7614 (Print)}, doi = {10.12989/eas.2017.12.4.409}, pages = {409 -- 423}, year = {2017}, abstract = {This paper proposes a quick and simplified method to describe masonry vaults in global seismic analyses of buildings. An equivalent macro-element constituted by a set of six trusses, two for each transverse, longitudinal and diagonal direction, is introduced. The equivalent trusses, whose stiffness is calculated by fully modeled vaults of different geometry, mechanical properties and boundary conditions, simulate the vault in both global analysis and local analysis, such as kinematic or rocking approaches. A parametric study was carried out to investigate the influence of geometrical characteristics and mechanical features on the equivalent stiffness values. The method was numerically validated by performing modal and transient analysis on a three naves-church in the elastic range. Vibration modes and displacement time-histories were compared showing satisfying agreement between the complete and the simplified models. This procedure is particularly useful in engineering practice because it allows to assess, in a simplified way, the effectiveness of strengthening interventions for reducing horizontal relative displacements between vault supports.}, language = {en} } @incollection{Mandelartz2007, author = {Mandelartz, Johannes}, title = {VDI-Richtlinien und Standards zu RFID}, series = {RFID in der Instandhaltung. (Forum Vision Instandhaltung)}, booktitle = {RFID in der Instandhaltung. (Forum Vision Instandhaltung)}, publisher = {Verl. Praxiswissen}, address = {Dortmund}, isbn = {978-3-89957-061-8}, pages = {169 -- 179}, year = {2007}, language = {de} } @incollection{Mandelartz2009, author = {Mandelartz, Johannes}, title = {VDI-Richtlinien - mit Technischen Regeln Wirtschaftlichkeit erh{\"o}hen und Standards setzen}, series = {Betriebliche Instandhaltung}, booktitle = {Betriebliche Instandhaltung}, publisher = {Springer}, address = {Berlin [u.a.]}, isbn = {978-3-642-00502-2}, doi = {10.1007/978-3-642-00502-2_26}, pages = {311 -- 317}, year = {2009}, abstract = {Der Verein Deutscher Ingenieure e.V. (VDI) ist ein gemeinn{\"u}tziger, wirtschaftlich und politisch unabh{\"a}ngiger, technisch-wissenschaftlicher Verein von Ingenieuren und Naturwissenschaftlern. Mit {\"u}ber 137 000 pers{\"o}nlich zugeordneten Mitgliedern ist er eine der gr{\"o}ßten Ingenieur-Vereinigungen Europas und gilt in Deutschland als f{\"u}hrender Sprecher der Technik und der Ingenieure. 1856 gegr{\"u}ndet, hat er viele f{\"u}r die Technik wesentliche Entwicklungen in Gang gesetzt, so im Bereich der technischen {\"U}berwachung, der technischen Regelsetzung und Normung, der Arbeitsstudien, im gewerblichen Rechtsschutz und im Patentwesen. Seit seiner Gr{\"u}ndung sieht es der VDI als seine Aufgabe, "das Zusammenwirken aller geistiger Kr{\"a}fte der Technik im Bewusstsein ethischer Verantwortung zu f{\"o}rdern" und die Lebensm{\"o}glichkeiten aller Menschen durch Entwicklung und sinnvoller Anwendung technischer Mittel zu verbessern.}, language = {de} } @article{Pieper2009, author = {Pieper, Martin}, title = {Vector hyperinterpolation on the sphere}, series = {Journal of approximation theory. 156 (2009), H. 2}, journal = {Journal of approximation theory. 156 (2009), H. 2}, isbn = {0021-9045}, pages = {173 -- 186}, year = {2009}, language = {en} } @article{HeuermannIbrahimHillebrand2007, author = {Heuermann, Holger and Ibrahim, Irfan and Hillebrand, J.}, title = {Vector-Signal-Generator with Two ?'?'-PLL's / Ibrahim, I. ; Hillebrand, J. ; Heuermann, H.}, series = {European Conference on Wireless Technologies, 2007. ECWT 2007 ; 8 - 10 October 2007 Munich, Germany}, journal = {European Conference on Wireless Technologies, 2007. ECWT 2007 ; 8 - 10 October 2007 Munich, Germany}, isbn = {978-2-87487-003-3}, pages = {1 -- 4}, year = {2007}, language = {en} } @article{ValeroBung2018, author = {Valero, Daniel and Bung, Daniel Bernhard}, title = {Vectrino profiler spatial filtering for shear flows based on the mean velocity gradient equation}, series = {Journal of Hydraulic Engineering}, volume = {144}, journal = {Journal of Hydraulic Engineering}, number = {7}, publisher = {ASCE}, address = {Reston, Va.}, issn = {0733-9429}, doi = {10.1061/(ASCE)HY.1943-7900.0001485}, year = {2018}, abstract = {A new methodology is proposed to spatially filter acoustic Doppler velocimetry data from a Vectrino profiler based on the differential mean velocity equation. Lower and upper bounds are formulated in terms of physically based flow constraints. Practical implementation is discussed, and its application is tested against data gathered from an open-channel flow over a stepped macroroughness surface. The method has proven to detect outliers occurring all over the distance range sampled by the Vectrino profiler and has shown to remain applicable out of the region of validity of the velocity gradient equation. Finally, a statistical analysis suggests that physically obtained bounds are asymptotically representative.}, language = {en} } @inproceedings{DoeringZillerHortmanns2003, author = {D{\"o}ring, Bernd and Ziller, Claudia and Hortmanns, M.}, title = {Ventilation of double facades by external dynamic wind pressure}, series = {11th International Conference on Wind Engineering. 1}, booktitle = {11th International Conference on Wind Engineering. 1}, publisher = {The Wind Science and Engineering Research Center}, address = {Lubbock, Tex.}, organization = {International Conference on Wind Engineering <11, 2003, Lubbock, Tex.>}, pages = {721 -- 730}, year = {2003}, language = {en} } @book{GrundmannBommesFricke2003, author = {Grundmann, Reinhard and Bommes, Leonard and Fricke, J{\"u}rgen}, title = {Ventilatoren}, publisher = {Vulkan-Verlag}, address = {Essen}, isbn = {3-8027-3200-6}, year = {2003}, language = {de} } @article{KindmannKrausLaumannetal.2022, author = {Kindmann, Rolf and Kraus, Matthias and Laumann, J{\"o}rg and Vette, Jan}, title = {Verallgemeinerte Berechnungsmethode f{\"u}r in Beton eingespannte Stahlprofile - Einspanntiefen, Tragf{\"a}higkeitsnachweise und Bemessungshilfen}, series = {Stahlbau}, volume = {93}, journal = {Stahlbau}, number = {Early View}, publisher = {Ernst \& Sohn GmbH}, address = {Berlin}, issn = {1437-1049}, doi = {10.1002/stab.202200024}, pages = {1 -- 25}, year = {2022}, abstract = {St{\"u}tzen und Tr{\"a}ger aus Stahlprofilen k{\"o}nnen in Fundamente oder W{\"a}nde aus Stahlbeton einbetoniert werden. Diese Anschl{\"u}sse wirken in der Regel wie Einspannungen, die eine ausreichende Einspanntiefe erfordern. Im Folgenden wird eine verallgemeinerte Berechnungsmethode f{\"u}r in Stahlbetonkonstruktionen eingespannte Stahlprofile aus gewalzten I-Profilen, geschweißten I-Profilen, runden Hohlprofilen, eckigen Hohlprofilen und einzelligen Kastenquerschnitten vorgestellt. F{\"u}r Beanspruchungen infolge einachsiger Biegung um die starke und schwache Profilachse werden der profilabh{\"a}ngige Ansatz der Betondruckspannungen im Einspannbereich und die Ermittlung der Einspanntiefe behandelt. Unter Ber{\"u}cksichtigung der Normalkraft werden an den maßgebenden Stellen Tragf{\"a}higkeitsnachweise f{\"u}r die Stahlprofile gef{\"u}hrt. Als Erg{\"a}nzung zu den Berechnungsformeln werden Bemessungshilfen zur Verf{\"u}gung gestellt, die die Wahl der mitwirkenden Breiten und der Einspanntiefen erleichtert.}, language = {de} } @book{Dienst1979, author = {Dienst, Karl-Jakob}, title = {Verallgemeinerte Vierecke in projektiven R{\"a}umen / Karl Jakob Dienst}, publisher = {Techn. Hochsch., Fachbereich Mathematik}, address = {Darmstadt}, pages = {12 S.}, year = {1979}, language = {de} } @article{MangHaulena1995, author = {Mang, Thomas and Haulena, Friedhelm}, title = {Veranstaltung des 15. Kolloquiums Chemie und Technologie makromolekularer Stoffe: w{\"a}ssrige Kunststoffdispersionen, FH Aachen (1994)}, series = {Farbe und Lack. 101 (1995), H. 1}, journal = {Farbe und Lack. 101 (1995), H. 1}, isbn = {0014-7699}, pages = {72 -- 72}, year = {1995}, language = {de} } @article{Golland2020, author = {Golland, Alexander}, title = {Verantwortlichkeit, Data Breach, das Ende von Fax \& E-Mail: Aufsichtsbeh{\"o}rden mit streitbaren Thesen}, series = {DSB Datenschutz-Berater}, volume = {44}, journal = {DSB Datenschutz-Berater}, number = {4}, publisher = {DFV Mediengruppe}, address = {Frankfurt a.M.}, isbn = {0170-7256}, pages = {98 -- 100}, year = {2020}, language = {de} } @article{StarkeKampker1999, author = {Starke, G{\"u}nther and Kampker, M.}, title = {Verbesserte Roboterprogrammierung f{\"u}r die werkstattorientierte Fertigung}, series = {DVS-Berichte. 199 (1999)}, journal = {DVS-Berichte. 199 (1999)}, isbn = {0418-9639}, pages = {84 -- 90}, year = {1999}, language = {de} }