11,642 research outputs found
Combing Euclidean buildings
For an arbitrary Euclidean building we define a certain combing, which
satisfies the `fellow traveller property' and admits a recursive definition.
Using this combing we prove that any group acting freely, cocompactly and by
order preserving automorphisms on a Euclidean building of one of the types
A_n,B_n,C_n admits a biautomatic structure.Comment: 32 pages. Published copy, also available at
http://www.maths.warwick.ac.uk/gt/GTVol4/paper2.abs.htm
Agency Behavior in a Nonprofit Setting: Effects of the 1984 Supreme Court NCAA Decision
The NCAA is commonly viewed as a cartel. We model the cartel relationship between the member teams and the NCAA central organization as a principal-agent relationship. Our model predicts imperfect agency behavior on the part of the NCAA with corresponding overregulation relative to the level preferred by the member teams. We empirically test the model by examining the impact of the 1984 Supreme Court decision that reassigned the telecast rights for intercollegiate football from the NCAA to the individual member teams. Our empirical estimates of telecasts, attendance, and competitive balance support the prediction of imperfect agency behavior by the NCAA.NCAA, Intercollegiate Football, Broadcast Regulation, Antitrust Policy
Development of a realistic stress analysis for fatigue analysis of notched composite laminates
A finite element stress analysis which consists of a membrane and interlaminar shear spring analysis was developed. This approach was utilized in order to model physically realistic failure mechanisms while maintaining a high degree of computational economy. The accuracy of the stress analysis predictions is verified through comparisons with other solutions to the composite laminate edge effect problem. The stress analysis model was incorporated into an existing fatigue analysis methodology and the entire procedure computerized. A fatigue analysis is performed upon a square laminated composite plate with a circular central hole. A complete description and users guide for the computer code FLAC (Fatigue of Laminated Composites) is included as an appendix
Recommended from our members
Development and Demonstration of a TDOA-Based GNSS Interference Signal Localization System
Background theory, a reference design, and demonstration
results are given for a Global Navigation Satellite
System (GNSS) interference localization system comprising a
distributed radio-frequency sensor network that simultaneously
locates multiple interference sources by measuring their signalsâ
time difference of arrival (TDOA) between pairs of nodes in
the network. The end-to-end solution offered here draws from
previous work in single-emitter group delay estimation, very long
baseline interferometry, subspace-based estimation, radar, and
passive geolocation. Synchronization and automatic localization
of sensor nodes is achieved through a tightly-coupled receiver
architecture that enables phase-coherent and synchronous sampling
of the interference signals and so-called reference signals
which carry timing and positioning information. Signal and crosscorrelation
models are developed and implemented in a simulator.
Multiple-emitter subspace-based TDOA estimation techniques
are developed as well as emitter identification and localization
algorithms. Simulator performance is compared to the CramérRao
lower bound for single-emitter TDOA precision. Results are
given for a test exercise in which the system accurately locates
emitters broadcasting in the amateur radio band in Austin, TX.Aerospace Engineering and Engineering Mechanic
A Graphical Approach to GPS Software-Defined Receiver Implementation
Global positioning system (GPS) software-defined
receivers (SDRs) offer many advantages over their hardwarebased
counterparts, such as flexibility, modularity, and upgradability.
A typical GPS receiver is readily expressible as a block
diagram, making a graphical approach a natural choice for
implementing GPS SDRs. This paper presents a real-time, graphical
implementation of a GPS SDR, consisting of two modes:
acquisition and tracking. The acquisition mode performs a twodimensional
fast Fourier transform (FFT)-based search over code
offsets and Doppler frequencies. The carrier-aided code tracking
mode consists of the following main building blocks: correlators,
code and carrier phase detectors, code and carrier phase filters,
a code generator, and a numerically-controlled oscillator. The
presented GPS SDR provides an abstraction level that enables
future research endeavors.Aerospace Engineering and Engineering Mechanic
Mapping the potential within a nanoscale undoped GaAs region using a scanning electron microscope
Semiconductor dopant profiling using secondary electron imaging in a scanning
electron microscope (SEM) has been developed in recent years. In this paper, we
show that the mechanism behind it also allows mapping of the electric potential
of undoped regions. By using an unbiased GaAs/AlGaAs heterostructure, this
article demonstrates the direct observation of the electrostatic potential
variation inside a 90nm wide undoped GaAs channel surrounded by ionized
dopants. The secondary electron emission intensities are compared with
two-dimensional numerical solutions of the electric potential.Comment: 7 pages, 3 figure
Employing dynamic fuzzy membership functions to assess environmental performance in the supplier selection process
The proposed system illustrates that logic fuzzy can be used to aid management in assessing a supplier's environmental performance in the supplier selection process. A user-centred hierarchical system employing scalable fuzzy membership functions implement human priorities in the supplier selection process, with particular focus on a supplier's environmental performance. Traditionally, when evaluating supplier performance, companies have considered criteria such as price, quality, flexibility, etc. These criteria are of varying importance to individual companies pertaining to their own specific objectives. However, with environmental pressures increasing, many companies have begun to give more attention to environmental issues and, in particular, to their suppliersâ environmental performance. The framework presented here was developed to introduce efficiently environmental criteria into the existing supplier selection process and to reflect on its relevant importance to individual companies. The system presented attempts to simulate the human preference given to particular supplier selection criteria with particular focus on environmental issues when considering supplier selection. The system considers environmental data from multiple aspects of a suppliers business, and based on the relevant impact this will have on a Buying Organization, a decision is reached on the suitability of the supplier. This enables a particular supplier's strengths and weaknesses to be considered as well as considering their significance and relevance to the Buying OrganizationPeer reviewe
Twenty first century standards for thermal comfort : fostering low carbon building design and operation
Nearly 50% of energy consumed in the developed world is consumed in buildings. Despite regulation intent, many new buildings are energy profligate. Thermal comfort standards are partly responsible for this increase in consumption. In this volume, Roaf et al. have described the evolution of current comfort standards and problems inherent in buildings they shape, and have discussed two new methods of regulating thermal comfort in buildings which recognize human adaptation and have potential for reduced energy demand. These new methods incorporate adaptation through a fixed heating and cooling threshold approach (similar to Japanese Cool-Biz) or through heating and cooling setpoints calculated based on outdoor conditions(using CEN standard equations). The impact on comfort and energy demand of these new approaches is investigated for a London office building. Variables such as future climate, future building upgrades, setback temperatures, internal gains and ventilation are also explored. Adoption of the new approaches gave a 50% reduction in heating and cooling energy for the simulated office. The new approach together with optimized setback temperatures, ventilation strategies and higher efficiency equipment gives predicted heating and cooling energy demand close to zero. Recommendations for future regulation, design and operation of buildings are proposed
Aspects of management options for pasture-based dairy production stocked at two cows per hectare
End of project reportWhite clover in association with Rhizobium bacteria have the capacity to fix or convent atmospheric N into plant available N. This can make a considerable contribution to sward productivity. One of the objectives of this experiment was to determine the upper carrying capacity of grass-white clover swards receiving 90 kg fertilizer N/ha. A second objective was to examine the impact of grass-clover swards on mineral-N in the soil and losses of nitrate-N from soil to drainage water during the winter. This experiment was conducted at Solohead Research Farm. There were three treatments: (i) A grass-only treatment (FN) stocked at 2.0 cows per ha in 2003 and 2.2 cows per ha during 2004, 2005 and 2006. This treatment received an average of 226 kg per ha of fertilizer N per year during these years. (ii) A grass-clover treatment (WC) stocked at the same rates as FN and received an average of 90 kg per ha of fertilizer N per year during the experiment. (iii) A grass-only treatment (CC) that was gradually converted over to grass-clover during the experiment and stocked at 2.0 cows per ha throughout the experiment. Fertilizer N input was gradually lowered from 150 kg per ha in 2003 to a target of 90 kg per ha in 2005 and 2006
- âŠ