781 research outputs found
Introducing strain-rate dependent work material properties into the analysis of orthogonal cutting
An analysis is presented in which cutting speed, depth of cut and
certain strain-rate dependent work material properties are taken into
account. Good agreement between theory and experiment is shown over a
wide range of cutting conditions
Flow along tool-chip interface in orthogonal metal cutting
In recent papers it has been suggested that over part of the toolchip
contact zone the chip does not slide but sticks to the tool, chip
flow taking place by shear within the body of the chip. Sticking
contact is inconsistent with steady state cutting and in this paper a
slip-line field model of chip flow is presented which does not include
sticking contact and which is consistent with the relevant experimental
observations
Note: estimating the charge size in explosive forming of sheet metal
Note: Estimating the charge size in explosive forming of sheet metal
In the explosive forming of sheet metal some relatively easy method
of estimating the size of the charge is needed. This short note describes
a method in which the size of the charge is found by equating the work done
in forming the component to that part of the explosive energy available
for doing work on the component … [cont]
Preliminary report on the analysis of the stresses in a die-bolster combination
An analysis is presented of the stresses in a carbide die-steel
bolster combination. Results from a computer treatment of this analysis
are given in tabular and graphical form. Suggestions are made as to the
choice of interface diameters, and a nomogram is drawn enabling the maximum
allowable interference to be selected
Calculating the shear angle in orthogonal metal cutting from fundamental stress-strain-strain rate properties of the work material
An analysis of the orthogonal metal cutting process is made which
enables the shear angle to be calculated from certain fundamental properties
of the work material and the specified cutting conditions. Shear angles
are calculated for a range of cutting conditions and good agreement is
shown between theory and experiment. In particular, such trends as the
decrease in shear angle with decrease in cutting speed and the tendency
for the chip to become discontinuous at slow cutting speeds which are found
experimentally and cannot be explained in terms of previous shear angle
analyses, are shown to be consistent with the present analysis
Lines, Circles, Planes and Spheres
Let be a set of points in , no three collinear and not
all coplanar. If at most are coplanar and is sufficiently large, the
total number of planes determined is at least . For similar conditions and
sufficiently large , (inspired by the work of P. D. T. A. Elliott in
\cite{Ell67}) we also show that the number of spheres determined by points
is at least , and this bound is best
possible under its hypothesis. (By , we are denoting the
maximum number of three-point lines attainable by a configuration of
points, no four collinear, in the plane, i.e., the classic Orchard Problem.)
New lower bounds are also given for both lines and circles.Comment: 37 page
Superfield Description of a Self-Dual Supergravity a la MacDowell-Mansouri
Using MacDowell-Mansouri theory, in this work, we investigate a superfield
description of the self-dual supergravity a la Ashtekar. We find that in order
to reproduce previous results on supersymmetric Ashtekar formalism, it is
necessary to properly combine the supersymmetric field-strength in the
Lagrangian. We extend our procedure to the case of supersymmetric Ashtekar
formalism in eight dimensions.Comment: 19 pages, Latex; section 6 improve
Measurement of the Electric and Magnetic Polarizabilities of the Proton
The Compton scattering cross section on the proton has been measured at
laboratory angles of 90 and 135 using tagged photons in the
energy range 70--100 MeV and simultaneously using untagged photons in the range
100--148~MeV. With the aid of dispersion relations, these cross sections were
used to extract the electric and magnetic polarizabilities, and
respectively, of the proton. We find
in agreement with a model-independent dispersion sum rule, and
where the errors shown are statistical, systematic, and model-dependent,
respectively. A comparison with previous experiments is given and global values
for the polarizabilities are extracted.Comment: 35 pages, 11 PostScript figures, uses RevTex 3.
Pest and disease management system for supporting winter oilseed rape decisions (PASSWORD) - vaildation phase (HGCA Project Report No. 390)
Pests and particularly diseases cause serious loss of yield and quality in winter oilseed rape estimated to exceed £80 million/annum in some years. These losses have occurred despite an annual expenditure of about £3.5 million for insecticides and £12 million on fungicides. Decision-making is difficult because there is complex spatial and temporal variation in pest and disease problems and improved guidance is required. The main objective of this project was to test new disease models developed in the first phase of this project and deliver a decision support system for both pest and disease control in oilseed rape.
The regional light leaf spot forecast is well-established and reliable and indicates an increased risk of this disease in spring 2006. A new regional forecast for stem canker incidence preharvest has been developed and made available on the Internet. It was successful in 2004/05 and offers strategic guidance on risk provided weather factors are within the range used to develop the model. A four-stage crop-specific stem canker risk assessment method was developed that predicts the onset of phoma leaf spotting using post-harvest weather data and thermal time relationships for canker development and canker severity. Yield loss can then be calculated from canker severity and the economic impact of stem canker predicted.
There is some flexibility in the timing of fungicide sprays to control stem canker. Delays of 2 to 3 weeks beyond a 10-20% plants affected threshold did not adversely affect yield. Stem canker severity and yield of different cultivars showed large variation between years and sites and smaller, but significant, variation in responses to fungicide. When phoma leaf spot appears in late autumn, it is only when plants are small that stem canker is likely to cause yield loss. In commercial crops, there were consistent trends for higher yields to be associated with higher fungicide inputs. Light leaf spot was very difficult to control with fungicides in the Aberdeen area where use of resistant cultivars is essential. The most effective disease control was obtained using a combination of resistant cultivars and fungicides. In some years, responses to fungicides were not cost-effective and targeting their use to high-risk situations is necessary to give the best margins over input costs.
Close contact was maintained with potential users during the project and they influenced priorities and design features. The components of PASSWORD decision support system were tested and provide guidance for the management of invertebrate pests, phoma stem canker and light leaf spot. The system will be available to ArableDS for use in autumn 2006
Let's Work It Out (or We'll See You in Court): Litigation and Private Dispute Resolution in Vertical Exchange Relationships
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