A theoretical and experimental appraisal of airworthiness evaluation techniques for small light aeroplanes

This thesis was submitted for the degree of Doctor of Philosophy and awarded by the University of Southampton.A thorough evaluation of the airworthiness of a manned aircraft is vitally important, regardless of the size or function of the aircraft. However, the methods used in light and particularly microlight aircraft certification were largely based upon rules of thumb or methods better suited to larger, higher energy, aircraft programmes. A programme of research has been carried out to develop means by which microlight aircraft certification could be carried out appropriately to this class of aircraft. The stall and immediately post-stall behaviour of an aircraft are shown to be a function of the deceleration rate prior to the stall; therefore it is necessary to use a representative deceleration rate when determining the acceptability of stall and post-stall handling qualities. This research has found means by which the range of deceleration rates likely to be seen in a particular type can be estimated, so that flight test programmes can ensure these rates are included, and thus aircraft are confirmed to have acceptable stalling characteristics. Weightshift controlled microlight aeroplanes, using a Rogallo type wing, rarely show a conventional (square law) relationship between stalling speed and loading; the reason being identified as aeroelastic deformation of the wing with loading. A means by which stalling speed may be estimated for such aircraft at a variety of loadings has been developed. This will allow designers the maximum flexibility in determining operating limits and shows how the stall speed at various flight conditions may be predicted in aircraft operating documentation. The spin is a serious and potentially fatal mode of flight; a spinning evaluation, even for non-aerobatic aeroplanes, is therefore essential. A best practice has been developed and tested for the spin-resistance or spinning evaluation of microlight aeroplanes, including equipment, aircraft and crew preparation, and reporting. The developed methodology is shown to be successful, using the results of certification flight test programmes, and the in-service safety record of aircraft which had been evaluated using these methods. The tumble mode is a little known mode of departure from controlled flight experienced by weightshift controlled microlight aeroplanes. It has been a very significant factor in fatal accident records, being non-recoverable without the use of external safety devices. The mode consists of a nose-down autorotation at a rate of up to 400°/s. The tumble entry mechanism is explained, and advice to operators developed which should prevent tumble entry. Evidence is shown of the nature of the developed tumble – both modelled and through wind tunnel results, which explain how the autorotation occurs. It is also shown how this theory may be applied during testing of an aircraft to develop a tumble resistant aircraft

A study of the earthworm populations of young mineral soils, with particular reference to colliery spoil

Not availabl

Historical Overview: The Parliamentary Library from Past to Present

Parliamentary libraries (also known under various terminologies such as federal libraries, legislative libraries, information resource centers, documentation centers, or reference services) enhance the research and information capacity of parliaments. As their histories show, however, some also came to consider their constituencies as lying beyond the confines of their parent legislature.published or submitted for publicatio

Crude oil: using a large case to teach introductory economics

Problem-based learning is rather labor intensive for teaching staff. In addition, the problem-based structure does not work always optimally in practice. Brainstorming during pre-discussion of tasks becomes very superficial, preparation of the students is far from optimal, and post-discussion is more focused on repeating what is already in the book than on the task being discussed. However, these problems can be solved.This paper discusses a number of innovations in the format of the standard problem-based course. The uses of a large case study and the role of lectures in this, a virtual learning environment, subgroup activities, mind maps in post-discussion, and writing will be discussed. The combination of these innovations increases the efficiency of the group meetings and provides an opportunity to reduce the number of tutor group meetings. The approach that is discussed here is both useful for people who want to introduce problem-based learning as a learning approach in an efficient way as for those who want to improve on an existing problem based learning system.Economics ;

Diffusional phenomena in membrane separation processes

Nowadays membrane filtration processes are used industrially as an alternative to conventional separation methods. Membrane separation methods can be divided into classes according to their separation characteristics: (i) separation by sieving action; (ii) separation due to a difference in affinity and diffusivity; (iii) separation due to a difference in charge of molecules; (iv) carrier-facilitated transport, and (v) the process of (time-) controlled released by diffusion. In all these cases diffusion processes play an important role in the transport mechanism of the solutes. Various mechanisms have been distinguished to describe the transport in membranes: transport through bulk material (dense membranes), Knudsen diffusion in narrow pores, viscous flow in wide pores or surface diffusion along pore walls. In practice, the transport can be a result of more than only one of these mechanisms. For all of these mechanisms models have been derived. The characteristics of a membrane, e.g. its crystallinity or its charge, can also have major consequences for the rate of diffusion in the membrane, and hence for the flux obtained. Apart from the diffusion transport processes in membranes mentioned above, other important diffusion processes are related to membrane processes, viz. diffusion in the boundary layer near the membrane (concentration polarization phenomena) and diffusion during membrane formation. The degree of concentration polarization is related to the magnitude of the mass transfer coefficient which, in turn, is influenced by the diffusion coefficient. The effect of concentration polarization can be rather different for the various membrane processes. The phase inversion membrane formation mechanism is determined to a large extent by the kinetic aspects during membrane formation, which are diffusion of solvent and of non-solvent and the kinetics of the phase separation itself

On the intersection of tolerance and cocomparability graphs.

Tolerance graphs have been extensively studied since their introduction, due to their interesting structure and their numerous applications, as they generalize both interval and permutation graphs in a natural way. It has been conjectured by Golumbic, Monma, and Trotter in 1984 that the intersection of tolerance and cocomparability graphs coincides with bounded tolerance graphs. Since cocomparability graphs can be efficiently recognized, a positive answer to this conjecture in the general case would enable us to efficiently distinguish between tolerance and bounded tolerance graphs, although it is NP-complete to recognize each of these classes of graphs separately. This longstanding conjecture has been proved under some – rather strong – structural assumptions on the input graph; in particular, it has been proved for complements of trees, and later extended to complements of bipartite graphs, and these are the only known results so far. Furthermore, it is known that the intersection of tolerance and cocomparability graphs is contained in the class of trapezoid graphs. Our main result in this article is that the above conjecture is true for every graph G that admits a tolerance representation with exactly one unbounded vertex; note that this assumption concerns only the given tolerance representation R of G, rather than any structural property of G. Moreover, our results imply as a corollary that the conjecture of Golumbic, Monma, and Trotter is true for every graph G = (V,E) that has no three independent vertices a, b, c ∈ V such that N(a) ⊂ N(b) ⊂ N(c), where N(v) denotes the set of neighbors of a vertex v ∈ V ; this is satisfied in particular when G is the complement of a triangle-free graph (which also implies the above-mentioned correctness for complements of bipartite graphs). Our proofs are constructive, in the sense that, given a tolerance representation R of a graph G, we transform R into a bounded tolerance representation R of G. Furthermore, we conjecture that any minimal tolerance graph G that is not a bounded tolerance graph, has a tolerance representation with exactly one unbounded vertex. Our results imply the non-trivial result that, in order to prove the conjecture of Golumbic, Monma, and Trotter, it suffices to prove our conjecture

An efficient format for a problem based introductory economics course

Problem-based learning is rather labor intensive for teaching staff. In addition, the problem-based structure does not work always optimally in practice. Brainstorming during pre-discussion of tasks becomes very superficial, preparation of the students is far from optimal, and post-discussion is more focused on repeating what is already in the book than on the task being discussed. However, these problems can be solved.This paper discusses a number of innovations in the format of the standard problem-based course. The uses of a large case study and the role of lectures in this, a virtual learning environment, subgroup activities, mind maps in post-discussion, and writing will be discussed. The combination of these innovations increases the efficiency of the group meetings and provides an opportunity to reduce the number of tutor group meetings. The approach that is discussed here is both useful for people who want to introduce problem-based learning as a learning approach in an efficient way as for those who want to improve on an existing problem based learning system.Economics ;

Forestry in the MAGNET model

Forestry data have been included in the global general equilibrium MAGNET model at LEI Wageningen UR. This provides the opportunity to analyse substitution between forestry, natural forests and agriculture with the model, which is essential to analyse biodiversity and greenhouse gas effects of different policies options with respect to feed, food and fuel. The report discusses the background of the GTAP land use database used for the implementation, the way it has been implemented and some first simulation results. The report investigates the weaknesses of the implementation determining a research agenda for further improvements of modeling forestry into the MAGNET model

Advances in the Production of Infiltrated Aluminium Parts Using Selective Laser Sintering

Recent advances in a rapid freeform fabrication process for the production of aluminium parts are considered. The methodology involves the formation of an unconstrained, resin bonded aluminium powder part by Selective Laser Sintering, the burnout of the resin, the partial transformation of the aluminium into a rigid aluminium nitride skeleton by reaction with the atmosphere under a magnesium/alumina blanket and the subsequent infiltration with a second aluminium alloy. Here we describe the process and consider potential applications. Strategies for controlling the growth of the aluminium nitride are also to be discussed.Mechanical Engineerin

Algorithms and almost tight results for 3-colorability of small diameter graphs.

The 3-coloring problem is well known to be NP-complete. It is also well known that it remains NP-complete when the input is restricted to graphs with diameter 4. Moreover, assuming the Exponential Time Hypothesis (ETH), 3-coloring cannot be solved in time 2o(n) on graphs with n vertices and diameter at most 4. In spite of extensive studies of the 3-coloring problem with respect to several basic parameters, the complexity status of this problem on graphs with small diameter, i.e. with diameter at most 2, or at most 3, has been an open problem. In this paper we investigate graphs with small diameter. For graphs with diameter at most 2, we provide the first subexponential algorithm for 3-coloring, with complexity 2O(nlogn√). Furthermore we extend the notion of an articulation vertex to that of an articulation neighborhood, and we provide a polynomial algorithm for 3-coloring on graphs with diameter 2 that have at least one articulation neighborhood. For graphs with diameter at most 3, we establish the complexity of 3-coloring by proving for every ε∈[0,1) that 3-coloring is NP-complete on triangle-free graphs of diameter 3 and radius 2 with n vertices and minimum degree δ=Θ(nε). Moreover, assuming ETH, we use three different amplification techniques of our hardness results, in order to obtain for every ε∈[0,1) subexponential asymptotic lower bounds for the complexity of 3-coloring on triangle-free graphs with diameter 3 and minimum degree δ=Θ(nε). Finally, we provide a 3-coloring algorithm with running time 2O(min{δΔ, nδlogδ}) for arbitrary graphs with diameter 3, where n is the number of vertices and δ (resp. Δ) is the minimum (resp. maximum) degree of the input graph. To the best of our knowledge, this is the first subexponential algorithm for graphs with δ=ω(1) and for graphs with δ=O(1) and Δ=o(n). Due to the above lower bounds of the complexity of 3-coloring, the running time of this algorithm is asymptotically almost tight when the minimum degree of the input graph is δ=Θ(nε), where ε∈[12,1), as its time complexity is 2O(nδlogδ)=2O(n1−εlogn) and the corresponding lower bound states that there is no 2o(n1−ε)-time algorithm