1,351 research outputs found
PCSYS: The optimal design integration system picture drawing system with hidden line algorithm capability for aerospace vehicle configurations
A vehicle geometric definition based upon quadrilateral surface elements to produce realistic pictures of an aerospace vehicle. The PCSYS programs can be used to visually check geometric data input, monitor geometric perturbations, and to visualize the complex spatial inter-relationships between the internal and external vehicle components. PCSYS has two major component programs. The between program, IMAGE, draws a complex aerospace vehicle pictorial representation based on either an approximate but rapid hidden line algorithm or without any hidden line algorithm. The second program, HIDDEN, draws a vehicle representation using an accurate but time consuming hidden line algorithm
Exploiting the Design Freedom of RM
This paper details how Rapid Manufacturing (RM) can overcome the restrictions imposed by the
inherent process limitations of conventional manufacturing techniques and become the enabling
technology in fabricating optimal products. A new design methodology capable of exploiting
RM’s increased design freedom is therefore needed. Inspired by natural world structures of trees
and bones, a multi-objective, genetic algorithm based topology optimisation approach is
presented. This combines multiple unit cell structures and varying volume fractions to create a
heterogeneous part structure which exhibits a uniform stress distribution.Mechanical Engineerin
Multivariate Analysis, Retrieval, and Storage System (MARS). Volume 1: MARS System and Analysis Techniques
A method for rapidly examining the probable applicability of weight estimating formulae to a specific aerospace vehicle design is presented. The Multivariate Analysis Retrieval and Storage System (MARS) is comprised of three computer programs which sequentially operate on the weight and geometry characteristics of past aerospace vehicles designs. Weight and geometric characteristics are stored in a set of data bases which are fully computerized. Additional data bases are readily added to the MARS system and/or the existing data bases may be easily expanded to include additional vehicles or vehicle characteristics
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Impact Absorbent Rapid Manufactured Structures (IARMS)
Rapid Manufacturing (RM) is increasingly becoming a viable manufacturing process due
to dramatic advantages that it facilitates in the area of design complexity. Through the
exploration of the design freedom afforded by RM, this paper introduces the concept and initial
research surrounding Impact Absorbent Rapid Manufactured Structures (IARMS), with an
application in sports personal protective equipment (PPE). Designs are based on the cellular
structure of foams; the inherent advantages of the cellular structure are used as a basis to create
IARMS that have the potential to be optimised for a specific impact absorbent response. The
paper provides some initial results from compression testingMechanical Engineerin
Bipolarons from long range interactions: Singlet and triplet pairs in the screened Hubbard-Froehlich model on the chain
We present details of a continuous-time quantum Monte-Carlo algorithm for the
screened Hubbard-Froehlich bipolaron. We simulate the bipolaron in one
dimension with arbitrary interaction range in the presence of Coulomb
repulsion, computing the effective mass, binding energy, total number of
phonons associated with the bipolaron, mass isotope exponent and bipolaron
radius in a comprehensive survey of the parameter space. We discuss the role of
the range of the electron-phonon interaction, demonstrating the evolution from
Holstein to Froehlich bipolarons and we compare the properties of bipolarons
with singlet and triplet pairing. Finally, we present simulations of the
bipolaron dispersion. The band width of the Froehlich bipolaron is found to be
broad, and the decrease in bandwidth as the two polarons bind into a bipolaron
is found to be far less rapid than in the case of the Holstein interaction. The
properties of bipolarons formed from long range electron-phonon interactions,
such as light strongly bound bipolarons and intersite pairing when Coulomb
repulsion is large, are found to be robust against screening, with qualitative
differences between Holstein and screened Froehlich bipolarons found even for
interactions screened within a single lattice site.Comment: 20 pages, 17 figure
Application of Bryan's algorithm to the mobility spectrum analysis of semiconductor devices
A powerful method for mobility spectrum analysis is presented, based on Bryan's maximum entropy algorithm. The Bayesian analysis central to Bryan's algorithm ensures that we avoid overfitting of data, resulting in a physically reasonable solution. The algorithm is fast, and allows the analysis of large quantities of data, removing the bias of data selection inherent in all previous techniques. Existing mobility spectrum analysis systems are reviewed, and the performance of the Bryan's algorithm mobility spectrum (BAMS) approach is demonstrated using synthetic data sets. Analysis of experimental data is briefly discussed. We find that BAMS performs well compared to existing mobility spectrum methods
A holistic multi-scale approach to using 3D scanning technology in accident reconstruction
Three-dimensional scanning and documentation methods are becoming increasingly employed by law enforcement personnel for crime scene and accident scene recording. Three-dimensional documentation of the victim’s body in such cases is also increasingly used as the field of forensic radiology and imaging is expanding rapidly. These scanning technologies enable a more complete and detailed documentation than standard autopsy. This was used to examine a fatal pedestrian-vehicle collision where the pedestrian was killed by a van whilst crossing the road. Two competing scenarios were considered for the vehicle speed calculation: the pedestrian being projected forward by the impact or the pedestrian being carried on the vehicle’s bonnet. In order to assist with this, the impact area of the accident vehicle was scanned using laser surface scanning, the victim was scanned using postmortem CT and micro-CT and the data sets were combined to virtually match features of the vehicle to injuries on the victim. Micro-CT revealed additional injuries not previously detected, lending support to the pedestrian-carry theory
Multivariate Analysis, Retrieval, and Storage System (MARS). Volume 4: Turbojet and Turbofan Data Base (By Engine)
A partial listing of turbojet and turbofan engine specifications data, as provided by the MARS (Multivariable Data Analysis, Retrieval, and Storage) system, was given for a number of engines
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