Matching methods to produce maps for pest risk analysis to resources

Decision support systems (DSSs) for pest risk mapping are invaluable for guiding pest risk analysts seeking to add maps to pest risk analyses (PRAs). Maps can help identify the area of potential establishment, the area at highest risk and the endangered area for alien plant pests. However, the production of detailed pest risk maps may require considerable time and resources and it is important to match the methods employed to the priority, time and detail required. In this paper, we apply PRATIQUE DSSs to Phytophthora austrocedrae, a pathogen of the Cupressaceae, Thaumetopoea pityocampa, the pine processionary moth, Drosophila suzukii, spotted wing Drosophila, and Thaumatotibia leucotreta, the false codling moth. We demonstrate that complex pest risk maps are not always a high priority and suggest that simple methods may be used to determine the geographic variation in relative risks posed by invasive alien species within an area of concern

Integration of crosswind forces into train dynamic modelling

In this paper a new method is used to calculate unsteady wind loadings acting on a railway vehicle. The method takes input data from wind tunnel testing or from computational fluid dynamics simulations (one example of each is presented in this article), for aerodynamic force and moment coefficients and combines these with fluctuating wind velocity time histories and train speed to produce wind force time histories on the train. This method is fast and efficient and this has allowed the wind forces to be applied to a vehicle dynamics simulation for a long length of track. Two typical vehicles (one passenger, one freight) have been modelled using the vehicle dynamics simulation package ‘VAMPIRE®’, which allows detailed modelling of the vehicle suspension and wheel—rail contact. The aerodynamic coefficients of the passenger train have been obtained from wind tunnel tests while those of the freight train have been obtained through fluid dynamic computations using large-eddy simulation. Wind loadings were calculated for the same vehicles for a range of average wind speeds and applied to the vehicle models using a user routine within the VAMPIRE package. Track irregularities measured by a track recording coach for a 40 km section of the main line route from London to King's Lynn were used as input to the vehicle simulations. The simulated vehicle behaviour was assessed against two key indicators for derailment; the Y/Q ratio, which is an indicator of wheel climb derailment, and the Δ Q/Q value, which indicates wheel unloading and therefore potential roll over. The results show that vehicle derailment by either indicator is not predicted for either vehicle for any mean wind speed up to 20 m/s (with consequent gusts up to around 30 m/s). At a higher mean wind speed of 25 m/s derailment is predicted for the passenger vehicle and the unladen freight vehicle (but not for the laden freight vehicle)

A Green's function formulation for a nonlinear potential flow solution applicable to transonic flow

Routine determination of inviscid subsonic flow fields about wing-body-tail configurations employing a Green's function approach for numerical solution of the perturbation velocity potential equation is successfully extended into the high subsonic subcritical flow regime and into the shock-free supersonic flow regime. A modified Green's function formulation, valid throughout a range of Mach numbers including transonic, that takes an explicit accounting of the intrinsic nonlinearity in the parent governing partial differential equations is developed. Some considerations pertinent to flow field predictions in the transonic flow regime are discussed

A fuselage/tank structure study for actively cooled hypersonic cruise vehicles, summary

A detailed analytical study was made to investigate the effects of fuselage cross section (circular and elliptical) and the structural arrangement (integral and nonintegral tanks) on aircraft performance. The vehicle was a 200 passenger, liquid hydrogen fueled Mach 6 transport designed to meet a range goal of 9.26 Mn (5000 NM). A variety of trade studies were conducted in the area of configuration arrangement, structural design, and active cooling design in order to maximize the performance of each of three point design aircraft: (1) circular wing-body with nonintegral tanks, (2) circular wing-body with integral tanks and (3) elliptical blended wing-body with integral tanks. Aircraft range and weight were used as the basis for comparison. The resulting design and performance characteristics show that the blended body integral tank aircraft weights the least and has the greatest range capability, however, producibility and maintainability factors favor nonintegral tank concepts

An evaluation of potentially useful separator materials for nickel-cadmium (Ni-Cd] satellite batteries

An evaluation intended to determine the potential suitability and probable efficacy of a group of separator materials for use in nickel-cadmium (Ni-Cd) satellite batteries was carried out. These results were obtained using test procedures established in an earlier evaluation of other separator materials, some of which were used in experimental battery cells subjected to simulated use conditions. The properties that appear to be most important are: high electrolyte absorptivity, good electrolyte retention, low specific resistivity, rapid wettability and low resistance to air permeation. Wicking characteristics and wet-out time seem to be more important with respect to the initial filling of the battery with the electrolyte

Identities for hyperelliptic P-functions of genus one, two and three in covariant form

We give a covariant treatment of the quadratic differential identities satisfied by the P-functions on the Jacobian of smooth hyperelliptic curves of genera 1, 2 and 3

Chiral exponents in O(N) x O(m) spin models at O(1/N^2)

The critical exponents corresponding to chirality are computed at O(1/N^2) in d-dimensions at the stable chiral fixed point of a scalar field theory with an O(N) x O(m) symmetry. Pade-Borel estimates for the exponents are given in three dimensions for the Landau-Ginzburg-Wilson model at m = 2.Comment: 8 latex page

The provision of distance education within the HE sector - some areas for concern

This paper presents a summary of the findings of a recent survey of the way in which UK higher education institutions (HEIs) are offering distance education (DE) courses, the types of courses being offered, and their modes of delivery. From analysis of the findings of this survey, it is apparent that the emphasis of HEIs is very much on the exploitation of available teaching technology in the delivery of DE courses. However, teaching at a distance is quite different from face-toface teaching, and the evidence suggests that many HEIs fail to implement any meaningful academic staff training for the new role of DE tutor. The authors consider the difficulties this presents to academic staff who are required to move from face-to-face teaching to online facilitating. The paper concludes with an examination of the current provision of staff development and training within UK HEIs and suggests the type of academic staff training required if DE courses are to become truly core activities