An analytical and experimental assessment of flexible road ironwork support structures

This paper describes work undertaken to investigate the mechanical performance of road ironwork installations in highways, concentrating on the chamber construction. The principal aim was to provide the background research which would allow improved designs to be developed to reduce the incidence of failures through improvements to the structural continuity between the installation and the surrounding pavement. In doing this, recycled polymeric construction materials (Jig Brix) were studied with a view to including them in future designs and specifications. This paper concentrates on the Finite Element (FE) analysis of traditional (masonry) and flexible road ironwork structures incorporating Jig Brix. The global and local buckling capacity of the Jig Brix elements was investigated and results compared well with laboratory measurements. FE models have also been developed for full-scale traditional (masonry) and flexible installations in a surrounding flexible (asphalt) pavement structure. Predictions of response to wheel loading were compared with full-scale laboratory measurements. Good agreement was achieved with the traditional (masonry) construction but poorer agreement for the flexible construction. Predictions from the FE model indicated that the use of flexible elements significantly reduces the tensile horizontal strain on the surface of the surrounding asphaltic material which is likely to reduce the incidence of surface cracking

Laboratory mix design of asphalt mixture containing reclaimed material

This paper presents a study on the production of asphalt test specimens in the laboratory containing reclaimed asphalt. The mixtures considered were stone mastic asphalt concrete mixtures containing up to 30% of reclaimed asphalt. Specimens were compacted to the reference density obtained from the Marshall mix design. Gyration compaction method was used for preparing specimens for the experimental programme, while coring and cutting methods and X-ray computed tomography (CT) were used to investigate the change in properties within the specimens and to validate the selected methodology.The study concluded that gyratory compaction is suitable to produce homogeneous test specimens also for mixtures containing high amount of reclaimed asphalt. Nevertheless, preliminary trials for each material are mandatory, as well as final coring and trimming of the specimens due to side effects

Impact of human disturbance on coastal birds: population consequences derived from behavioural responses

Disturbance of wildlife is inevitable in a world with a rapidly increasing human population. Whilst improving engagement with the natural world can have the benefit of encouraging people to help protect it, there is also the issue of increased potential for damaging effects of disturbance. A better understanding is needed of the circumstances under which disturbance would be expected to be a conservation problem, either alone or in combination with the impacts of other human activities. The aim of this thesis is therefore to address these questions: using wintering waders in estuarine habitats as the study system and taking a joint fieldwork and simulation modelling approach. Fieldwork was centred on Poole Harbour; an estuary and wetland of international importance located on the south coast of the UK. Disturbance experiments and observations showed that bird responses to disturbance are highly variable and related to factors including body mass, environmental conditions, site quality, and disturbance type. The energetic and lost-feeding-opportunity costs of responding to individual disturbance events were relatively small and therefore considered unlikely to cause major reductions in individual body condition or significantly limit overwintering population size, given observations of present-day spatial and temporal patterns of human activities. Simulation modelling using two types of individual-based model (IBM) supported this conclusion. Although high levels of disturbance can have a significant impact on wintering bird populations, current frequencies of human activities in Poole Harbour were not found to be reducing the carrying capacity of the site. Increased disturbance frequencies were predicted to be problematic, however, in combination with environmental change that reduced bird ability to meet their daily energy requirements: such as loss of foraging habitat through sea level rise, or reductions in prey availability due to over-exploitation. This has important implications for identifying the most effective conservation management methods. As well as site-specific management recommendations, this research contributes to understanding of the mechanisms by which disturbance may or may not have a significant impact on wintering wader populations; along with applications to other systems; and tools and general principles that conservation managers and decision makers can use to prioritise further investigation and action

Test methods and influential factors for analysis of bonding between bituminous pavement layers

The durability and maintenance of pavements depend on several factors. One of the most influential is the bond between layers. This bond is responsible for ensuring all layers behave as a single entity, reducing cracks and deformation of the pavement. Several methods, developed by different authors over the past 30 years, to measure bonding between layers are analyzed in this paper. Different research lines are discussed, concluding that the most influential variables are: tack coat type, dosage, mixture type, surface characteristics, temperature, and emulsion breaking time. In order to reach the highest bond strength values, the following factors should be considered: high values of surface macro-texture, low temperatures, the use of heat-adhesive emulsion, a dosage from 300 to 450 g/m2 of residual bitumen and the compaction after emulsion break. Moreover, a non-destructive test method to assess tack coat dosage on site is proposed

Projective fibres schemes

This thesis takes the construction (due to Grothendieck) of the projective fibred scheme of a coherent sheaf and iinvestigates certain aspects of its geometry, (and, in Chapter IV, topology). In Chapter I, after quoting the basic definitions, of the projective fibred scheme of ϵ with its projection π : ρϵ·→X and fundamental invertible sheaf ϴ(1) on ρϵ, and giving some simple illustrative examples, we turn (§§ 2,3) to some particular features of the geometry, notably the Fitting subschemes and the dominating component (and interactions between the two). Here and throughout most of the work we keep close to geometrical intuition by considering only coherent modules on locally-neotherian, reduced schemes. In an appendix we introduce some sheaves that are in: a sense universal for coherent sheaves on projective varieties. (These do not play any essential role in the rest of the thesis). Chapter II is concerned with the canonical homomorphism X, ϵ→π*ϴ (1) which is known to be an isomorphism when ϵ is locally-free. We extend this result to a larger class of sheaves and show, for example, that X is an isomorphism if ρϵ normal. In view of this result, and for general reasons, it is of interest to look for examples of smooth projective fibred schemes. This we do in Chapter III and show that a "generic" Module ϵ. of the type that locally has a resolution 0→0pu→θqu→∈u→0, (U, smooth where p(x) =0, has smooth ρϵ in a neighbourhood of ρϵ(x). Chapter IV considers the (singular) cohomology ring of PE when ϵ is a sheaf on a complex variety (with the classical topology). We include a discussion of the effect on cohomology of blowing-up a smooth variety with centre of smooth subvariety

Fatigue resistance: is it possible having a unique response?

The mechanical characterisation of the asphalt concrete in terms of both the fatigue resistance and the stiffness modulus is necessary to use any design method of the flexible road pavements. Different kinds of test are usually used in experimental work such as bending tests, uniaxial tests, etc., but sometimes they do not give the same answer. In this paper mechanical characterization was carried out by means of fatigue tests undertaken with two most used testing machines for asphalt material: two point bending (2PB) test at IFSTTAR in Nantes (France) and four point bending (4PB) test at University of Palermo, in Palermo (Italy). Different strain controlled tests were undertaken for the same material under the same loading conditions, frequency and temperature (15 Hz and 20˚C), according to the European standard 12697 part 24 and 26. The first results of this interlaboratory activity are showed in this paper

Predicting and measuring vertical track displacements on soft subgrades

Several analytical models can be used to predict the propagation of bending waves in the track/embankment system. A model of a Euler beam on a Winkler foundation is studied and used to demonstrate how the magnitude of displacements are dependent on train speed and track damping. The methods by which the model parameters may be calculated are discussed and their relative advantages and disadvantages are considered. From this study it is possible to form practical suggestions on methods by which the design of rail tracks can be adjusted to limit the maximum transient deflections as a train passes. This paper compares results from a predictive method with the results of in-situ assessments

Sleep Disorders and Medical Conditions in Women

Abstract Sleep disorders affect women differently than they affect men and may have different manifestations and prevalences. With regard to obstructive sleep apnea (OSA), variations in symptoms may cause misdiagnoses and delay of appropriate treatment. The prevalence of OSA appears to increase markedly after the time of menopause. Although OSA as defined by the numbers of apneas/hypopneas may be less severe in women, its consequences are similar and perhaps worse. Therapeutic issues related to gender should be factored into the management of OSA. The prevalence of insomnia is significantly greater in women than in men throughout most of the life span. The ratio of insomnia in women to men is approximately 1.4:1.0, but the difference is minimal before puberty and increases steadily with age. Although much of the higher prevalence of insomnia in women may be attributable to the hormonal or psychological changes associated with major life transitions, some of the gender differences may result from the higher prevalence of depression and pain in women. Insomnia's negative impact on quality of life is important to address in women, given the high relative prevalence of insomnia as well as the comorbid disorders in this population. Gender differences in etiology and symptom manifestation in narcolepsy remain understudied in humans. There is little available scientific information to evaluate the clinical significance and specific consequences of the diagnosis of narcolepsy in women. Restless legs syndrome (RLS) is characterized by an urge to move the legs or other limbs during periods of rest or inactivity and may affect as much as 10% of the population. This condition is more likely to afflict women than men, and its risk is increased by pregnancy. Although RLS is associated with impaired quality of life, highly effective treatment is available.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63103/1/jwh.2007.0561.pd