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  Subjects -> ENGINEERING (Total: 1957 journals)
    - CHEMICAL ENGINEERING (150 journals)
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    - ENGINEERING (1124 journals)
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    - MECHANICAL ENGINEERING (73 journals)

ENGINEERING (1124 journals)            First | 1 2 3 4 5 6 7 8 | Last

Developments in Geotechnical Engineering     Full-text available via subscription   (1 follower)
Developments in Mineral Processing     Full-text available via subscription  
Diálogos Interdisciplinares     Open Access  
Diamond Light Source Proceedings     Full-text available via subscription  
Digital Signal Processing     Hybrid Journal   (3 followers)
Discrete Optimization     Full-text available via subscription   (4 followers)
Doct-Us Journal     Open Access  
Documents pour l'histoire des techniques     Open Access   (1 follower)
Dyes and Pigments     Hybrid Journal   (3 followers)
Dyna     Open Access  
Dynamical Systems: An International Journal     Hybrid Journal   (1 follower)
El Hombre y la Máquina     Open Access  
Electromagnetics     Hybrid Journal   (2 followers)
Electrophoresis     Hybrid Journal   (5 followers)
Elsevier Geo-Engineering Book Series     Full-text available via subscription   (2 followers)
Elsevier Ocean Engineering Series     Full-text available via subscription  
Embedded Systems Letters, IEEE     Hybrid Journal   (14 followers)
Energies     Open Access   (1 follower)
Energy and Power Engineering     Open Access   (6 followers)
Energy Conversion and Management     Hybrid Journal   (6 followers)
Energy Engineering     Full-text available via subscription   (8 followers)
Energy for Sustainable Development     Hybrid Journal   (8 followers)
Energy Procedia     Open Access   (2 followers)
Energy Science & Engineering     Open Access   (2 followers)
Energy Science and Technology     Open Access   (9 followers)
Energy Sources, Part A: Recovery, Utilization, and Environmental Effects     Hybrid Journal   (2 followers)
Energy Sources, Part B: Economics, Planning, and Policy     Hybrid Journal   (5 followers)
Energy Systems     Hybrid Journal   (7 followers)
ENGEVISTA     Open Access  
ENGI : Revista Electrónica de la Facultad de Ingenieria     Open Access  
Engineer : Journal of the Institution of Engineers, Sri Lanka     Open Access  
Engineering     Open Access   (2 followers)
Engineering & Technology     Hybrid Journal   (15 followers)
Engineering Analysis with Boundary Elements     Hybrid Journal   (1 follower)
Engineering Computations     Hybrid Journal   (4 followers)
Engineering Economics     Open Access   (4 followers)
Engineering Economist, The     Hybrid Journal   (3 followers)
Engineering Education     Open Access  
Engineering Failure Analysis     Hybrid Journal   (21 followers)
Engineering Geology     Hybrid Journal   (8 followers)
Engineering Journal     Open Access   (1 follower)
Engineering Management Journal     Hybrid Journal   (12 followers)
Engineering Management Research     Open Access   (4 followers)
Engineering Management Reviews     Open Access   (1 follower)
Engineering Optimization     Hybrid Journal   (5 followers)
Engineering Sciences     Open Access  
Engineering Studies     Hybrid Journal  
Engineering With Computers     Hybrid Journal   (5 followers)
Engineering, Technology & Applied Science Research     Open Access  
Entramado     Open Access  
Entropy     Open Access   (3 followers)
Environmental & Engineering Geoscience     Full-text available via subscription   (2 followers)
Environmental and Ecological Statistics     Hybrid Journal   (5 followers)
Environmetrics     Hybrid Journal  
Épités - Épitészettudomány     Full-text available via subscription   (1 follower)
EPJ Photovoltaics     Open Access  
Ergonomics in Design: The Quarterly of Human Factors Applications     Hybrid Journal   (5 followers)
ESAIM: Control Optimisation and Calculus of Variations     Full-text available via subscription  
ESAIM: Mathematical Modelling and Numerical Analysis     Full-text available via subscription   (3 followers)
ESAIM: Proceedings     Open Access  
Estuaries and Coasts     Hybrid Journal   (1 follower)
EURASIP Journal on Advances in Signal Processing     Open Access   (3 followers)
European Journal of Combinatorics     Full-text available via subscription  
European Journal of Engineering Education     Hybrid Journal   (1 follower)
European Journal of Lipid Science and Technology     Hybrid Journal   (1 follower)
European Journal of Mass Spectrometry     Full-text available via subscription   (8 followers)
European Medical Device Technology     Full-text available via subscription   (2 followers)
European Physical Journal - Applied Physics     Full-text available via subscription   (4 followers)
European Transport Research Review     Open Access   (9 followers)
Evolutionary Intelligence     Hybrid Journal  
Evolving Systems     Hybrid Journal  
Exacta     Open Access  
Experimental Techniques     Hybrid Journal   (15 followers)
Experiments in Fluids     Hybrid Journal   (3 followers)
Fibers and Polymers     Full-text available via subscription   (3 followers)
Filtration & Separation     Full-text available via subscription   (1 follower)
Finite Fields and Their Applications     Full-text available via subscription   (2 followers)
Fire Science Reviews     Open Access   (1 follower)
First Monday     Open Access   (108 followers)
Flexible Services and Manufacturing Journal     Hybrid Journal   (3 followers)
Flow, Turbulence and Combustion     Hybrid Journal   (13 followers)
Fluid Dynamics     Hybrid Journal   (5 followers)
Fluid Dynamics Research     Full-text available via subscription   (7 followers)
Fluid Phase Equilibria     Hybrid Journal   (1 follower)
Focus on Catalysts     Full-text available via subscription  
Focus on Pigments     Full-text available via subscription   (3 followers)
Focus on Powder Coatings     Full-text available via subscription   (2 followers)
Focus on Surfactants     Full-text available via subscription   (3 followers)
Food Engineering Reviews     Hybrid Journal   (2 followers)
Formación Universitaria     Open Access   (3 followers)
FORMakademisk     Open Access  
Formal Methods in System Design     Hybrid Journal   (6 followers)
Forschung     Hybrid Journal  
Forschung im Ingenieurwesen     Hybrid Journal  
Foundations and Trends in Systems and Control     Full-text available via subscription  
Foundations and Trends® in Communications and Information Theory     Full-text available via subscription   (5 followers)
Foundations and Trends® in Electronic Design Automation     Full-text available via subscription  
Foundations of Science     Hybrid Journal  
Frontiers in Aerospace Engineering     Open Access   (2 followers)
Frontiers in Energy     Hybrid Journal   (2 followers)

  First | 1 2 3 4 5 6 7 8 | Last

Forschung im Ingenieurwesen    Follow    
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1434-0860 - ISSN (Online) 0015-7899
     Published by Springer-Verlag Homepage  [2187 journals]   [SJR: 0.131]   [H-I: 10]
  • Key features of flexure hinges used as rotational joints
    • Abstract: Abstract This article is supposed to serve as a guide for the design of flexure hinges that act as rotational joints. Firstly, flexure hinges with concentrated and distributed compliance are reviewed. They can be modeled by linear beam theories or by the theory of Elastica, respectively. Secondly, the transition between these limit cases is investigated by finite element methods (FEM). A planar symmetric flexure hinge with a circular notch serves as an exemplary geometry. By extending the notch the compliance is distributed. The deflection curves and the kinetics of desired and parasitic motions are chosen as key features to be studied. The corresponding results are compressed into a pseudo-rigid-body model (PRBM) approximation for a range of geometries. It turned out that the concentrated compliance matches best with an ideal rotational joint, but even for small displacements large stresses occur so that its range of operation is small. Distributing the compliance increases the range of operation, however stiffness within the task space decreases dramatically so that the design of a flexure hinge becomes a tradeoff between the two concurring goals large stiffness and large range of operation.
      PubDate: 2013-10-23
  • Bildung von geordneten Konstruktionsfamilien unter Anwendung von
    • Abstract: Zusammenfassung Die Theorie der Konstruktionsähnlichkeit basiert auf der Theorie der physikalischen Ähnlichkeit. Das primäre Ziel dieser Arbeit ist eine derartige Auswahl von Konstruktionsmerkmalen in den einzelnen Typengrößen der Typenreihen, um identische: physikalische, stereomechanische aber auch einfache Zustände, wie in der Grundkonstruktion, zu erhalten. Die Grundaufzeichnungsform einer Konstruktion einer Typenreihe ist die programmierbare, grafische und relationale Parametrisierung.
      PubDate: 2013-10-18
  • On the determination of natural frequencies of a cantilever beam in free
           bending vibration: a rigid multibody approach
    • Abstract: Abstract A new approximate method for the determination of natural frequencies of a cantilever beam in free bending vibration by a rigid multibody system is proposed. Uniform Euler-Bernoulli cantilever beams with and without a lumped mass at the tips are considered. The modelling method consists of two steps. In the first step, the cantilever beam is replaced by lumped masses interconnected by massless flexible beams. In the second step, the massless flexible beams are replaced by massless rigid beams connected through revolute and prismatic joints with corresponding springs in them. Elastic properties of the massless flexible beams are modelled by the springs introduced. The method proposed is compared with similar ones in the literature.
      PubDate: 2013-10-08
  • Aufbau und Validierung eines Prozesskraftmodells für das
           kontinuierliche Wälzschleifen von Stirnradverzahnungen
    • Abstract: Zusammenfassung Zur Verbesserung der Tragfähigkeit und der Laufruhe von Verzahnungen ist es Stand der Technik, einsatzgehärtete Verzahnungen nach der Wärmebehandlung abschließend hartfein zu bearbeiten. Eine Möglichkeit für die Hartfeinbearbeitung ist das kontinuierliche Wälzschleifen, das aufgrund der hohen Produktivität ein industriell etablierter Prozess ist. Trotz des weitreichenden industriellen Einsatzes liegen bisher nur begrenzt wissenschaftliche Kenntnisse über das kontinuierliche Wälzschleifen von Verzahnungen vor. Ein Grund dafür sind die komplexen Kontaktbedingungen zwischen Schleifschnecke und Werkstück beim Wälzschleifen. Während der Bearbeitung befinden sich immer mehrere Zahnflanken gleichzeitig im Eingriff mit der Schleifschnecke. Dies erschwert unter anderem eine Übertragung vorhandener Erkenntnisse aus anderen, besser erforschten Schleifprozessen (z. B. dem diskontinuierlichen Profilschleifen). Die veränderlichen Kontaktbedingungen führen zu einer ausgeprägten Dynamik im Prozess, die eine Herausforderung sowohl für die Maschinenentwicklung, die Regelungstechnik als auch für die Prozessauslegung darstellt. Die Kenntnis der zu erwartenden Bearbeitungskräfte und ihres zeitlichen Verlaufs ist daher notwendig, um die Dynamik des Prozesses einerseits beschreiben und andererseits optimieren zu können. Hierzu müssen sowohl der Betrag als auch die Richtung der lokal auftretenden Zerspanungskräfte bekannt sein. Allerdings ist die Bestimmung der auftretenden Zerspanungskräfte im Wälzschleifprozess nur mit großem Aufwand möglich. Bisher existieren keine systematischen Untersuchungen zum Einfluss der Maschineneinstellparameter auf die Zerspanungskräfte im Wälzschleifprozess.
      PubDate: 2013-09-25
  • Näherungsverfahren zur Berechnung von Kerbspannungen und -dehnungen
           bei Plastizität und Kriechen
    • Abstract: Zusammenfassung Diese Arbeit stellt vier Näherungsverfahren zur Abschätzung der Spannungskonzentration an Kerben vor. Es handelt sich um die Neuber-Regel, die Glinka-Methode, die Interpolationsmethode und eine neu entwickelte, numerische Neuber-Regel. Dabei werden Kriechen und Plastizität bei proportionaler Belastung und konstanter Temperatur berücksichtigt. Außerdem wird ein Verfahren zur Berechnung der Hauptspannungen und -dehnungen im Kerbgrund beschrieben. Um diese Verfahren zu verifizieren, werden FEM-Berechnungen an einer gelochten Scheibe und einer Kerbprobe als Beispiele unter Zugbelastung durchgeführt. Zusätzlich werden die durchschnittlichen Abweichungen der Näherungsverfahren von den FEM-Werten ermittelt. Es wird damit gezeigt, dass alle vier Methoden die FEM-Werte mit hoher Genauigkeit approximieren.
      PubDate: 2013-09-24
  • Development of new models of performance correction factors of centrifugal
           pumps as a function of Reynolds number and specific speed
    • Abstract: Abstract The performance characteristics of a small centrifugal pump having a specific speed of 20 min−1 are measured when pumping two industrial Newtonian oils of viscosities 75 and 646 cSt, at value of Reynolds number near 103. The diminishing of the performance in the case of these oils compared to water is about 50 to 80 %. It decreases with the reduction of Reynolds number. The correction factors of head, of flow rate and efficiency, are determined depending on Reynolds number, and they are compared with those obtained using the European KSB empirical method, the American method ANSI/HI and the semi-empirical method based on the analysis of power losses. For centrifugal pumps of a specific speed below 50 min−1, the fall in performance increases with the decrease of Reynolds number and specific speed. The fall in efficiency is more important than the fall of the other performance parameters. A good agreement is obtained between experimental results and predicted results using the three above mentioned methods, with the exception of the efficiency correction factor obtained by the method of power losses analysis, in the range of Reynolds numbers between 103 and 105. The expression of correction performance factors based on the Reynolds number is universal. It allows to distinguish the ranges of correction factors falls, and to know the economic limitations of the use of centrifugal pumps. A fall of head and flow rate correction factors of over 10 % occurs at values of Reynolds number below 104. But, the fall of efficiency correction factor of over 10 % occurs at values of Reynolds number below 105. To facilitate to the professionals the calculation of the performance correction factors of centrifugal pumps, new models are proposed in this study according to Reynolds number and specific speed.
      PubDate: 2013-08-23
  • Pulsating flow of a couple stress fluid in a channel with permeable walls
    • Abstract: Abstract The paper is concerned with an analytical study of the oscillatory flow of a couple stress fluid in a channel, bounded by two permeable walls. The couple stress fluid is considered to be injected into the medium through one of the walls with a given velocity and to be sucked off by the other wall with an equal velocity. The problem is solved by using a perturbation technique. Analytical expressions for the velocity and volumetric flow rate are derived for the oscillatory flow of the couple stress fluid flowing in the channel. By using the method of parametric variation, distribution of the velocity of the couple stress fluid, change in velocity profiles at different instants of time, change in volumetric flow rate with change in frequency and cross-flow Reynolds number are computed, by considering an illustrative example. The study reveals that both the velocity and the volumetric flow rate are quite sensitive to the couple stress parameter, the frequency of oscillation and also to the cross-flow Reynolds number. The study will be immensely useful in resolving different problems associated with oil industries.
      PubDate: 2013-04-12
  • Laserbeschriftung von Hartferritmagneten zur Kennzeichnung von
    • Abstract: Zusammenfassung Durch das vorgestellte Verfahren sollen Gussbauteile durch eine magnetische Kennzeichnung eindeutig beschriftet und zudem mit Produktionsdaten versehen werden. Hierzu werden informationstragende Magnete im Druckguss dicht unter die Oberfläche eingegossen. Mittels Laserbeschriftung mit einem diodengepumpten Ytterbium-Faserlaser wurden auf der Oberfläche der Hartferritmagnete Informationen, unteranderem in Form von DataMatrix-Codes, eingebracht. Verwendet wurden preisgünstige Strontiumferrit-Magnete. Aufgrund der durch den Laser hervorgerufenen lokalen Erwärmung über die Curie-Temperatur, kommt es zu Aufschmelzvorgängen und Werkstoffveränderungen an der Magnetoberfläche und folglich zur Entmagnetisierung des entsprechenden Volumens. Zudem wird die Oberfläche geometrisch verändert. Dies führt in den beschrifteten Bereichen zu einer messbaren Verringerung der magnetischen Flussdichte. Diese Unterschiede in der magnetischen Flussdichte lassen sich optisch mit Magnetfeldbetrachter oder durch die Messung mit Magnetfeldsensoren, wie zum Beispiel Hallsensoren, auslesen. Dieser Beitrag beschäftigt sich vornehmlich mit den Veränderungen auf der Magnetoberfläche sowie mit Visualisierungs- und Messmethoden. Die Ergebnisse erster Gießversuche werden präsentiert, um die Stabilität der magnetischen Markierung zu bestätigen.
      PubDate: 2013-04-04
  • Elastic limits of a radially heated thick-walled cylindrically curved
    • Abstract: Abstract In analogy to the theory of wide curved beams, the basic equations for a cylindrically curved panel of homogeneous thickness in a state of plane strain subject to a radial temperature gradient are derived. The ends of this thick-walled shell are presupposed to be guided in such a way that a displacement in circumferential direction may occur and that the radius of the initial middle surface remains unchanged. Then, couples act on those ends, giving rise to pure bending conditions. Based thereon, the stresses occurring for a heated inner and/or outer surface are analyzed, and—taking thermal softening and hence a reduced yield stress into account—the elastic limits according to the yield criteria of Tresca and von Mises are discussed comprehensively.
      PubDate: 2013-03-28
  • Ausgleichsrechnung mit Tschebyscheffpolynomen
    • Abstract: Zusammenfassung Es wird eine Methode vorgestellt um Datensätze mit Zusatzbedingungen in einem Intervall mittels Tschebyscheffpolynomen zu approximieren. Eine geeignete Segmentierung des Intervalls ermöglicht in einzelnen Teilintervallen eine Tschebyscheffapproximation von geringem Grad. Man kann dadurch insgesamt mit weniger Tschebyscheffkoeffizienten auskommen, als bei einer einzigen hochgradigen Approximation des Gesamtintervalls. An den inneren Segmentgrenzen fordern wir Stetigkeit sowie an den Intervallgrenzen der beiden äußeren Segmente die Annahme vorgegebener Werte bis zur zweiten Ableitung. Mit Hilfe von Lagrangefaktoren und der Methode der kleinsten Quadrate formulieren wir ein Minimumproblem mit Nebenbedingungen. Dies führt auf ein lineares Gleichungssystem, dessen Lösung die entsprechenden Tschebyscheffkoeffizienten liefert.
      PubDate: 2013-03-28
  • Analysis of coupled dissipative dynamic systems of engineering using
           extended Hamiltonian        id-i-eq1">        format-t-e-x">$\mathcal{H}$ for
           classical and nonconservative Hamiltonian        class="a-plus-plus">H        class="a-plus-plus">∗       class="a-plus-plus">n for higher
           order Lagrangian systems
    • Abstract: Abstract Lagrange and Hamilton formalisms derived from variational calculus can be applied nearly in all engineering sciences. In this study, the reader is introduced using tensorial variables in covariant and contravariant forms, to the extended Lagrangian $\mathcal{L}$ and herewith to the modified momentum ${p}_{{k}}^{*}$ . Through both, the extended Hamiltonian $\mathcal{H}$ of a dissipative engineering system is derived to analyze the engineering system in an analytical way. In addition, a nonconservative Hamiltonian H ∗n for systems with elements of higher order is introduced in a similar manner. Moreover, different forms of extended Hamiltonian are represented. How these forms are achieved and how to derive the equations of generalized motion in different forms is also explained. As an example, a coupled electromechanical system in different formulations is given on behalf of the reader. The example is even extended to a case including some elements of higher order.
      PubDate: 2013-01-01
  • Assessing heat transfer processes: a critical view at criteria based on
           the second law of thermodynamics
    • Abstract: Abstract When a second law analysis is applied to a heat transfer process, the influence of boundary conditions on the chosen assessment criterion is of major importance. In this paper, three different sets of boundary conditions and three different assessment criteria based on the entropy generation are applied to a plate heat exchanger. The influence of the boundary conditions on the device’s operation and on the usefulness of the assessment criteria is discussed.
      PubDate: 2012-12-01
  • Simulation des Schwungrad-Reibschweißprozesses mit ABAQUS
    • Abstract: Zusammenfassung Obwohl die Technologie des Schwungrad-Reibschweißens seit Jahrzenten erfolgreich angewandt wird, sind die während der Schweißung ablaufenden Prozesse nur teilweise beschrieben. Die Entwicklung von Temperatur und Spannungsfeldern in den Schweißpartnern sind jedoch entscheidende Faktoren, um mögliche Gefügeumwandlungen, Vorschädigungen und Schweißgüten beurteilen zu können. Da die starke thermomechanische Wechselwirkung im Bereich der Fügezone analytische Berechnungsmethoden ausschließt, müssen numerische Methoden eingesetzt werden, um während der Schweißung einen Blick in das Innere der Bauteile zu erhalten. In der vorliegenden Arbeit wird ein von ABAQUS zur Verfügung gestelltes Modell in mehreren Punkten erweitert, um die physikalischen Effekte, die während der Schweißung ablaufen, besser abzubilden. Die Implementierung eines neuen Reibmodells sowie die Integration von Konvektionsrandbedingungen sind die grundlegenden Veränderungen. Die mit diesem Modell berechneten Daten werden anschließend mit Versuchsdaten verglichen, um die Güte der Simulation zu beurteilen.
      PubDate: 2012-12-01
  • Mathematical model of the ice protection of a human body at high
           temperatures of surrounding medium
    • Abstract: Abstract This paper presents a mathematical model describing the heat transfer inside of a human body at high temperatures of surrounding medium. The human body is considered as a slender body with heat transfer dominating in horizontal planes neglecting the heat fluxes in the vertical direction. Each body cross section is represented as an ellipse with five typical layers: inner and outer cores, muscles, fat layer and skin. The body is covered by the textile with embedded ice layer to protect the human from the overheating. The heat transfer within each horizontal plane is modelled using a simple sector model. With these simplifications the problem is reduced to the solution of the one dimensional heat conduction equation with certain initial and boundary conditions. The equation is solved numerically using inhouse code based on the finite differential method. Numerical calculations are performed with the aim to determine the ice layer thickness necessary to keep the temperature of the human body core at the temperature of 36.7∘±1∘ within one hour. Results of simulations were utilized to design a special protection clothes for rescue team working in the mining industry. The experiments with clothes supported the simulation prediction.
      PubDate: 2012-12-01
  • Experimentelle Untersuchung der thermischen Konvektion in einem geneigten
    • Abstract: Zusammenfassung Das Verhalten einer Flüssigkeitsströmung in einem engen vertikalen Spalt mit einer gekühlten und einer beheizten Seitenwand wurde experimentell in einer vergangenen Studie hinsichtlich des Wärme- und Massentransports untersucht (Heiland et al. in Heat Mass Transf 43:863–870, 2007). Dieser Studie folgend wurde unter Anwendung der Flüssigkristalltechnik zur Strömungssichtbarmachung eine Untersuchung der thermischen Konvektion in einer engen Kavität unter variablem Neigungswinkel durchgeführt. Geschwindigkeits- und Temperaturfeld der Strömung wurden vermessen. Unter anderem zeigen die Ergebnisse, dass ab einem Neigungswinkel von ca. 5∘–15∘ eine drastische Änderung der Strömungs- und Temperaturfeldtopologie auftritt, welche sich qualitativ bis zu einem Neigungswinkel von 90∘ nicht mehr ändert.
      PubDate: 2012-12-01
  • Plate bending for frame analysis by coupling method of singular integral
           operators method with finite elements
    • Abstract: Abstract The coupling of the Singular Integral Operators Method (SIOM) and the Finite Element Method (FEM) is proposed and investigated for the solution of plate bending problems. Such combination of the above two numerical methods gives more accurate results for the solution of plate bending problems in structural analysis. The plates are basic units of building frame structures, as well as to underground structures and thus the determination of bending moments around the plates is very important for the analysis of all kinds of structures. An application of plate bending problems is finally given to the determination of the bending moments in a rectangular plate with a rectangular hole in the center of the plate.
      PubDate: 2012-12-01
  • Prediction of thermal post buckling and deduction of large amplitude
           vibration behavior of spring–hinged beams
    • Abstract: Abstract A general energy formulation to predict the thermal post buckling behavior of uniform isotropic beams is presented in this paper. The hinged ends of the beam contain elastic rotational restraints to represent the actual practical support situation. The large amplitude vibration behavior of beams is deduced from the post buckling results. The classical hinged and clamped conditions can be obtained as the limiting cases of the rotational spring stiffness. The numerical results, in the form of the ratios of the post buckling to buckling loads for various maximum deflection ratios, are presented in the digital form. An alternate independent formulation, based on the nonlinear finite element formulation, is also used in this paper to validate the numerical results of the present work. Further, the results for the large amplitude vibrations, deduced from the thermal post buckling results are also presented and these results compare very well with the finite element results, available in the literature, for the large amplitude vibration problem. These comparisons show an excellent agreement not only for the present work on the proposed thermal post buckling formulation but also on the deduced results for the large amplitude vibration of beams with the ends elastically restrained against rotation (spring–hinged beams). The numerical results presented confirm the efficacy of the proposed methodology used for predicting the post buckling behavior and deducing the large amplitude vibration behavior of the spring–hinged beams.
      PubDate: 2012-06-01
  • Uncertainty and sensitivity analysis of properties of phase change
           micro/nanoparticles for thermal protection during cryosurgery
    • Abstract: Abstract Based on our previous study which tested the feasibility of protecting the healthy tissue around the cancerous tissue during cryosurgery by microencapsulated phase change materials (PCMs) with large latent heat and low thermal conductivity, uncertainties and sensitivities for thermal protection efficiency caused by the deviations of the PCM properties’ values, the PCMs concentration and the distance between the PCMs domain and the tumor domain were further investigated in this study. The preliminary results showed that the radius of the micro/nano PCM particle, the upper and lower phase transition temperatures of the PCM and the distance between the PCMs domain and the tumor domain should be accurately measured before performing thermal protection by PCMs during cryosurgery. Less than 20 % deviations of the heat capacities of solid and liquid PCM almost had no obvious influence on the thermal protection efficiency. The results obtained in this study will further help us to optimize the protection protocol by PCMs before performing cryosurgery.
      PubDate: 2012-06-01
  • Flow characteristics of the nasal cavity
    • Abstract: Abstract In the human nasal cavity the flow reciprocates carrying oxygen, carbon dioxide, humidity, internal energy and particles. Thus the nose is a multi functional organ of a very complex structure. In order to understand the flow as the basis of all functions two different measurements may be considered. One is local inside the cavity, the other is integral between inlet and outlet of the cavity. This work focuses on the integral pressure/flow rate relationship as function of time. We collect data from test persons and also data from 1:1 models which are build by rapid prototyping in a new segmented fashion. It is shown that the pressure/flow rate relationship follows always a polynomial of second order which is physically justifiable. The flexibility of the nasal cavity is demonstrated by using spray and strips. We find considerable effects on the pressure/flow rate relationship. The new technique of segmented models allows to see how the pressure loss distributes over the cavity. Working with model and physiological reality teaches the engineer a lesson: reproducibility is not reality.
      PubDate: 2012-06-01
  • Grundlagenuntersuchung zu den Strömungsverhältnissen in
           hochtourigen Turbinengleitlagern: Strömung in einem Konfusor mit
           einseitig bewegter Berandung
    • Abstract: Zusammenfassung Die Strömungsverhältnisse in einem schlanken Konfusor mit einseitig bewegter ebener Wand werden experimentell und numerisch für eine turbulente Reynolds-Zahl von 9,95×103 untersucht. Die Resultate können zum grundlegenden Verständnis für die Strömungen, die in Gleitlagertaschen für hochtourige Turbomaschinen in Schwerbauweise auftreten, verwendet werden. Hierbei zeigt sich, dass sich in unmittelbarer Nähe der bewegten Wand (Wellenzapfen) eine dünne turbulente Grenzschicht ausbildet, während die übrige Kanalgeometrie (Lagertasche) von einem turbulenten Totwasser mit nur sehr geringen Sekundärströmungen (Rezirkulationen) erfüllt ist. Durch den Vergleich mit detaillierten LDA-Messungen zeigte sich, dass das Realizable k–ε-Modell gut geeignet für die numerische Simulation solcher Strömungen ist.
      PubDate: 2012-06-01
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