Normalised Root Mean Square and Amplitude of Sidebands of Vibration Response as Tools for Gearbox Diagnosis

Quick assessment of the condition of gearboxes used in helicopters is a safety requirement. One of the most widely used helicopter on-board-mounted condition monitoring system these days is the Health and Usage Monitoring System. It has been specifically designed to monitor the condition of all safety-critical components operating in the helicopter through calculation of so-called condition indicators (CIs) - signal processing routines designed to output a single number that represents the condition of the monitored component. Among number of available parameters, there is a couple of CIs that over the years of testing have earned a reputation of being the most reliable measures of the gear tooth condition. At the same time, however, it has been observed that in some cases, those techniques do not properly indicate the deteriorating condition with the propagation of a gear tooth fault with the period of operation. Hence, three more robust methods have been suggested, which are discussed in this article

Airflow patterns in ventilated wall cavities

Though heating, insulation, wall claddings and cavity-wall construction are considered as measures for remediating moisture and condensation in buildings, ventilation of wall cavities has however become a mantra among architects and other building professionals. Holes of any size and shape are made and located on building facades based on the accepted wisdom that a little air movement will keep the wall cavities dry. Whilst ventilation has been found to be successful in the control of moisture and condensation in rooms and larger enclosures, there is however insufficient understanding of how it works in thin spaces with high aspect ratios, such as the wall cavities studied in this thesis.In order to put in place good control and management practices in the remediation of moisture and condensation in vertical wall cavities by natural ventilation, it is vital to understand the dynamics of airflow in these cavities. In this thesis therefore, different size and shape of slots were employed to numerically investigate the effects of size, spacing and number of the slots on the characteristics of the velocity fields (patterns of airflow and distributions of velocity) in different cavity models. The Reynolds-Averaged-Navier-Stokes (RANS) methodology was employed to simulate the cavity flows under different modelling conditions using FLUENT. The BS 5925 model, an empirical relation for predicting ventilation rates in rooms and other larger enclosures, was employed and modified to predict ventilation rates in these cavities. Experimentally, the mapping of the airstreams in these cavities was obtained under similar reference (inlet) wind speeds employed for the numerical investigations.The results of this study show that there exists a potential at higher wind speeds for natural ventilation in the remediation of moisture and condensation in the cavities of vertical walls. The steady state approach employed in the RANS-based computation of cavity flows in this thesis averages out the peak values of air velocities and therefore gives no information about regions of maxima or minima velocity values even at higher wind speeds. This makes the predicted air change rates insensitive to the inlet air velocities from the ventilation slots and therefore makes the results more applicable for long term control and management of moisture in these cavities. In order to therefore put in place short, medium and long term plans for remediation of moisture in these wall cavities, a time-dependent computation is required. This will also allow the efficiency of the cavity ventilation to be properly assessed. Using the modified BS 5925 model, reasonable predictions were obtained for the air change rates of the wall cavities with the different size of ventilation slots employed. Close agreements are also obtained at lower and higher wind speeds between the predicted ventilation rates from the modified BS 5925 model and the experimental results employed as benchmark for validating the results.EThOS - Electronic Theses Online ServiceEnglish Heritage and Irish HeritageGBUnited Kingdo

Effect of Chases with Renovation Techniques on the Load Carrying Capacity of Masonry Walls

From MDPI via Jisc Publications RouterHistory: accepted 2021-11-03, pub-electronic 2021-11-09Publication status: PublishedInfrastructure through the masonry walls (for example, wiring and piping works) are usually installed using chases in different directions. Introducing these chases in a newly built wall will affect its overall load carrying capacity. However, there has thus far been very limited research into the effects of chases on the response and load carrying capacity of walls. This study has been undertaken to evaluate the structural behaviour of new masonry walls having chases in both horizontal and vertical directions and subjected to compression load throughout an extensive experimental programme. In addition, two renovation techniques have been proposed to infill the chases created in small scale walls (wallettes). The first technique involved the use of plastic wire mesh and cement mortar, while the second incorporated using galvanized steel channel together with the plastic wire mesh and cement mortar. Furthermore, a reference case of wallette without chases has been considered to enable reasonable comparisons to check the effect of the chases and the efficiency of the proposed renovation techniques. The outcomes of this study were used to modify the design equations proposed in the relevant codes of practice. The obtained results showed a notable reduction in the load carrying capacity of the masonry wall due to the introduction of the chases with a reduction percentage of 29% compared to the masonry wall without chase. The percentage decrease depends on the depth of the chase and the inclination angle of the load flow. The walls with horizontal chases exhibited more reduction in the load carrying capacity compared to those with vertical chases. The adopted renovation techniques using galvanized steel channel and/or plastic wire mesh with cement mortar recovered 55% and 93% of the lost load carrying capacity due to the presence of the chase and the failure was due to the de-bonded phenomena of the infill materials. Suitable factors of safety have been proposed to be incorporated in the compressive strength and modulus of elasticity formulas of the masonry walls of the BS EN codes

Integration of point cloud data and hyperspectral imaging as a data gathering methodology for refurbishment projects using Building Information Modelling (BIM)

Purpose: Building information modelling (BIM) is a digital representation of the physical and functional characteristics of a building. Its use offers a range of benefits in terms of achieving the efficient design, construction, operation and maintenance of buildings. Applying BIM at the outset of a new build project should be relatively easy. However, it is often problematic to apply BIM techniques to an existing building, for example, as part of a refurbishment project or as a tool supporting the facilities management strategy, because of inadequacies in the previous management of the dataset that characterises the facility in question. These inadequacies may include information on as built geometry and materials of construction. By the application of automated retrospective data gathering for use in BIM, such problems should be largely overcome and significant benefits in terms of efficiency gains and cost savings should be achieved. Design/methodology/approach: Laser scanning can be used to collect geometrical and spatial information in the form of a 3D point cloud, and this technique is already used. However, as a point cloud representation does not contain any semantic information or geometrical context, such point cloud data must refer to external sources of data, such as building specification and construction materials, to be in used in BIM. Findings: Hyperspectral imaging techniques can be applied to provide both spectral and spatial information of scenes as a set of high-resolution images. Integrating of a 3D point cloud into hyperspectral images would enable accurate identification and classification of surface materials and would also convert the 3D representation to BIM. Originality/value: This integrated approach has been applied in other areas, for example, in crop management. The transfer of this approach to facilities management and construction would improve the efficiency and automation of the data transition from building pathology to BIM. In this study, the technological feasibility and advantages of the integration of laser scanning and hyperspectral imaging (the latter not having previously been used in the construction context in its own right) is discussed, and an example of the use of a new integration technique is presented, applied for the first time in the context of buildings

Reducing Flooding Impacts to the Built Environment: A Literature Review

The paper consists of the literature review and discussions that concerns the built environment, flooding, disaster risk management including resiliency and sustainability theory. The objective of this paper is to review any relevant works of literature in reducing the flooding impacts to the built environment in Malaysia, at the same time describing any potential improvements and current measures to handle the aftermath of flooding. Systematic literature review using reference material such as books, scholarly journals, previous studies, articles, and websites is carried out. The author also searched further for the references of the articles that were retrieved and repeated the process until a point where no new relevant articles come to light. The paper is significant in three ways; i) reducing the flood impacts by raising knowledge ii) providing responsibility measures in reducing flood from different perspectives iii) preparing ways to lessen the impacts of future flooding threats. The key findings of the paper are; a) Through knowledge application, the practice of reducing flooding impacts could be enhanced b) Flooding management should be carried out earlier before flooding attack but also remains later the event c) Disaster management plans must get ready to face with any uncertainties

The pharmacokinetics of medetomidine administered subcutaneously during Isoflurane anaesthesia in Sprague-Dawley rats

Anaesthetic protocols involving the combined use of a sedative agent, medetomidine, and an anaesthetic agent, isoflurane, are increasingly being used in functional magnetic resonance imaging (fMRI) studies of the rodent brain. Despite the popularity of this combination, a standardised protocol for the combined use of medetomidine and isoflurane has not been established, resulting in inconsistencies in the reported use of these drugs. This study investigated the pharmacokinetic detail required to standardise the use of medetomidine and isoflurane in rat brain fMRI studies. Using mass spectrometry, serum concentrations of medetomidine were determined in Sprague-Dawley rats during medetomidine and isoflurane anaesthesia. The serum concentration of medetomidine for administration with 0.5% (vapouriser setting) isoflurane was found to be 14.4 ng/mL (±3.0 ng/mL). The data suggests that a steady state serum concentration of medetomidine when administered with 0.5% (vapouriser setting) isoflurane can be achieved with an initial subcutaneous (SC) dose of 0.12 mg/kg of medetomidine followed by a 0.08 mg/kg/h SC infusion of medetomidine. Consideration of these results for future studies will facilitate standardisation of medetomidine and isoflurane anaesthetic protocols during fMRI data acquisition

Explaining and understanding state intervention into the lives of ‘troubled’ families

This article focuses attention on explaining and understanding state intervention into the lives of families deemed ‘troublesome’ with specific attention on the Troubled Families Programme. Launched in 2011, in part as a response to the London riots, the Troubled Families Programme represented an escalation and intensification of state intervention into the lives of families. Policy analyses have provided important perspectives on how we should explain and understand this government agenda as part of a process of neoliberal state crafting. This article offers a critical yet productive examination of these perspectives, arguing that their utility lies in how they can be employed, and therefore modified and adapted, in conjunction with studies of local practice which emphasise the messy realities of policy enactment and, with that, the possibility for contestation and challenge. Such an approach, based broadly on the tenets of critical realism, is founded on an alternative conception of state power, one that sees state power as having a more complex quality that is dependent on the agency of local actors

Prophylaxis for venous thromboembolic disease in pregnancy and the early postnatal period

Some women are at risk of forming blood clots in a deep vein during pregnancy, after a caesarean birth, or during the first few weeks after childbirth. If part of the clot breaks off and lodges in a blood vessel in the lungs, it can be life-threatening. Preventive treatments include blood-thinning drugs to prevent clots, support stockings, and exercise soon after the birth to keep circulation moving. However, some drugs might cause problems such as increased blood loss after the birth. Drugs used include heparin, low molecular weight heparin and aspirin. We included 16 randomised controlled studies in the review but only 13 trials with 1774 women contributed data for the outcomes of interest. We did not find enough evidence from the trials to be sure about the effects of these different preventive treatments.This means there is not enough evidence to show which are the best ways to prevent deep vein thrombosis (DVT) during or following pregnancy, or after a caesarean birth