Example Calculation (example + calculation)

Distribution by Scientific Domains


Selected Abstracts


A Dynamic Analysis of a Spatial Manipulator to Determine Payload Weight

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 7 2003
Carl D. Crane III
This paper presents a methodology whereby the payload weight of a serial manipulator can be determined from a minimum set of sensor data, i.e., joint angle and joint torque measurements. The particular manipulator geometry that is analyzed is a four degree-of-freedom serial chain that is commonly used in excavator systems. It was quite remarkable that a relatively simple solution was obtained for the payload weight considering that there are a total of nine unknown moments and cross moments of inertia of the payload together with the unknown location of the center of mass. Example calculations are presented. © 2003 Wiley Periodicals, Inc. [source]


Effective Dynamic Material Properties of Foam-like Microstructures

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005
S. Alvermann
The effective material parameters of a microstructured material can be found using homogenization procedures based on calculations of a Representative Volume Element (RVE) of the material. In our approach the RVE is calculated in frequency domain and inertia is taken into account, leading to a frequency dependent behavior of the RVE. With the frequency response of the RVE, effective dynamic properties of the material are calculated using an optimization procedure. Due to the frequency dependent material behavior on the microscale a viscoelastic constitutive equation is applied on the macroscale. An example calculation is presented for an auxetic 2-D foam-like microstructure which is modelled as a plane frame structure. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Modellierung von kurzwelliger solarer Strahlung bei der hygrothermischen Bauteilsimulation , numerische Lösung und analytischer Ansatz

BAUPHYSIK, Issue 1 2006
Doktorandin Claudia Finkenstein Dipl.-Ing.
Der vorliegende Beitrag präsentiert ein Modell zur Bestimmung der kurzwelligen solaren Strahlung an Bauteilen, das , basierend auf gemessenen Wetterdaten der direkten und diffusen solaren Strahlung auf die Horizontalfläche , für die Einbindung in numerische Simulationsprogramme geeignet ist. Damit wurde ein geschlossenes Konzept erarbeitet, das es erlaubt, die Strahlungswärmestromdichte infolge kurzwelliger direkter und diffuser Sonnenstrahlung auf beliebig orientierte und geneigte Wand- und Dachflächen unter Beachtung der Eigenverschattung an einem beliebigen Ort zu berechnen. Weiterhin stellt der Beitrag einen analytischen Ansatz für das gleiche Problem vor, mit dessen Hilfe auf einfache Weise z. B. Wirkungsanalysen durchgeführt werden können. Den Abschluß des Beitrags bildet die beispielhafte Berechnung einer nach verschiedenen Himmelsrichtungen orientierten Wandkonstruktion. Modelling of shortwave solar radiation within the hygrothermal simulation of building envelope parts , numerical solution and analytical approach. This article presents a model for the determination of shortwave solar radiation on building envelope parts, which is , based on measured weather data of direct and diffuse solar radiation on a horizontal surface , suitable to be integrated in computercodes for hygrothermal building part simulation. Therewith, firstly a well-rounded concept has been worked out, which allows to calculate the radiation flux on any orientated and sloped wall or roof construction at any location taking into account the self-shading. Furthermore, there is presented an analytical approach for the same problem that is suitable to perform sensitivity analyses with in an easy way. At the end of the article, an example calculation of a wall construction orientated into different directions is presented. [source]


Investigation into the traction coefficient in elastohydrodynamic lubrication

LUBRICATION SCIENCE, Issue 2 2004
Y. S. Wang
Abstract The elastohydrodynamic traction coefficients of two Chinese aviation lubricating oils were investigated for various loads, rolling velocities, and lubricant inlet temperatures using a self-made test rig. Traction coefficient versus slide-to-roll ratio curves were generated. The concept of critical load varying with the lubricant temperature is proposed. This paper presents a new empirical formula for the dynamic performance design of high-speed rolling bearings, that relates traction coefficient with normal load, rolling velocity, and lubricant inlet temperature. The coefficients of the formula may be computed by regression analysis of the experimental data. Two example calculations are presented. The predicted results from the formula agree well with experimental observations. [source]


Measurement error bias in pharmaceutical cost-effectiveness analysis

APPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 5-6 2006
*Article first published online: 20 DEC 200, Ian C. Marschner
Abstract Drug development in the pharmaceutical industry is increasingly influenced by measures of cost-effectiveness, such as cost per life-year gained, and some governments make decisions about whether to pay for drugs based on cost-effectiveness considerations. While cost per life-year gained is a key measure of cost-effectiveness, costs associated with the intermediate outcome of improving a biomarker, such as cholesterol level or blood pressure, provide important supplementary information, particularly where mortality data may be limited. In this case, cost-effectiveness can be interpreted as the additional cost per unit time of achieving an additional beneficial biomarker response to treatment. A problem in this context is that biomarker assessment is typically subject to measurement error which leads to bias in assessing the benefit of a drug, and hence in the assessment of its cost-effectiveness. We discuss the adjustment of cost-effectiveness analyses for measurement error and consider the potential magnitude of bias that can arise. Using example calculations in the context of cholesterol-lowering therapy, it is demonstrated that such biases can be significant, leading to costs being overestimated by in excess of 25%. Ignoring measurement error in cost-effectiveness analyses can, therefore, have a substantial effect on the interpretation of such analyses. Copyright © 2006 John Wiley & Sons, Ltd. [source]