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Investigation into the meshing friction heat generation and transient thermal characteristics of spiral bevel gears
Get PDFFriction loss and scuffing failure are two primary research subjects in improving the performance of spiral bevel gears. Aimed at improving the thermal characteristics with machine-setting parameter adjustment, a coupled thermo-elastic 3D finite element model has been developed to analyse the frictional heat generation and transient thermal behaviour of spiral bevel gears. The heat fluxes due to friction effects are applied to the gear tooth to investigate thermal characteristics and prediction of transient temperature fields. The resulting thermal characteristics agree with earlier work, thus verifying the model and numerical approach. This study permits an in-depth understanding of the temperature fields, together with the frictional heat generation process. Furthermore, by investigating the transient thermal behaviour among different pinion machine-setting parameters, the tilted and extended tooth contact pattern achieved by adjusting the machine-setting parameters can result in an optimal tooth contact pattern that produces a uniform temperature field of much lower value, thereby achieving higher efficiency of transmission along with stronger anti-scuffing performance
Learning and Living Overseas: Exploring Factors that Influence Meaningful Learning and Assimilation:How International Students Adjust to Studying in the UK from a Socio-Cultural Perspective
No full textThere is a considerable amount of research investigating students’ transition from college to university but it is important this focus is directed specifically towards the transition of international students, as the difficulties they face are profound. The literature surrounding international students seems to lack an in-depth understanding of how multiple contextual factors influence how students
adjust to Higher Education. Therefore, the present study utilizes Bronfenbrenner’s (2009) ecological theory of human development in order to understand both immediate and distal environmental influences and how they interact to impact on the individual’s development from a holistic perspective. Five international students participated in a time line interview.
Findings suggest that international students face a number of challenges when transitioning from their home country to study in higher education in the UK, particularly in the areas of language competence; cultural assimilation and social relationships. This in turn prevented meaningful learning occurring. Applying Bronfenbrenner’s theory, the participants’ broader environment was analysed, which encouraged an examination of the challenges they faced which regards to cultural influences, government influences and university policies, as well as influences from within their immediate environme
Control of metallo-supramolecular assemblies via steric, hydrogen bonding and argentophilic interactions; formation of a 3-dimensional polymer of circular helicates
Get PDFThis work shows how multiple non-covalent interactions are employed to control metallosupramolecular architectures and we demonstrate that a ligand, which contains two bidentate domains separated by a ArOH spacer, forms a mesocate when complexed with Ag(I). However, changing this to an ArOCH2CH2Ph spacer unit results in a 1-dimensional helical polymer upon reaction with the same cation. Reaction of Ag(I) with the ArOMe derivative gives a hexanuclear circular helicate which forms inter-assembly Ag⋯Ag interactions resulting in a 3-dimensional honeycomb-like polymer of hexanuclear circular helicates
From publishers to self-publishing: The disruptive effects of digitalisation on the book industry
No full textThis paper explores the structure of the book publishing industry postdigitalisation.
We argue that the introduction of successful e-book readers has belatedly given digitalisation the characteristics of a disruptive technology by
making self-publishing a serious option for authors. This has been supported by the entry of new types of intermediaries and the strengthening of others.
These changes have reduced the overall complexities for an author to get a book self-published. As a result, a larger share of the surplus from the book industry is likely going to authors, explaining the significant increase in the supply of books. The potential over-supply of books has created a new problem by making consumer search more difficult. We argue that digitalisation has shifted the potential market failure from inadequate supply of books to asymmetric information about quality. It remains to be seen whether the market will provide appropriate intermediaries to solve the associated asymmetric information problem and, if not, what appropriate interventions should be contemplated
Correlation and convolution filtering and image processing for pitch evaluation of 2D micro- and nano-scale gratings and lattices
Get PDFWe have mathematically explicated and experimentally demonstrated how a correlation and convolution filter can dramatically suppress the noise that coexists with the raster-scanned topographic signals of 2D gratings and lattices with 2-dimensional (2D) perspectives. To realize pitch evaluation, the true peaks’ coordinates have been precisely acquired after detecting the local maxima from the filtered signal, followed by image processing. The combination of 2D filtering, local maxima detection and image processing make up the pitch detection (PD) method. It is elucidated that the pitch average, uniformity, rotation angle and orthogonal angle can be calculated using the PD-method. This has been applied to the pitch evaluation of several 2D gratings and lattices, and the results are compared with the results of using the CG- and FT-method. The differences of pitch averages which are produced using the PD-, CG- and FT-methods are within 1.5 pixels. Moreover, the PD-method has also been applied to detect the dense peaks of Si (111) 77 surface and the HOPG basal plane
The Reduction of Vertical Interchannel Crosstalk: The Analysis of Localisation Thresholds for Natural Sound Sources
No full textIn subjective listening tests, natural sound sources were presented to subjects as vertically-oriented phantom images from two layers of loudspeakers, ‘height’ and ‘main’. Subjects were required to reduce the amplitude of the height layer until the position of the resultant sound source matched that of the same source presented from the main layer only (the localisation threshold). Delays of 0, 1 and 10 ms were applied to the height layer with respect to the main, with vertical stereophonic and quadraphonic conditions being tested. The results of the study showed that the localisation thresholds obtained were not significantly affected by sound source or presentation method. Instead, the only variable whose effect was significant was interchannel time difference (ICTD). For ICTD of 0 ms, the median threshold was −9.5 dB, which was significantly lower than the −7 dB found for both 1 and 10 ms. The results of the study have implications both for the recording of sound sources for three-dimensional (3D) audio reproduction formats and also for the rendering of 3D images
Exponential Log-Periodic Antenna Design Using Improved Particle Swarm Optimization with Velocity Mutation
No full textAn improved particle swarm optimization (PSO) method applied to the design of a new wideband log-periodic antenna (LPA) geometry is introduced. This new PSO variant, called PSO with velocity mutation (PSOvm), induces mutation on the velocities of those particles that cannot improve their position. The proposed LPA consists of wire dipoles with lengths and distances varied according to an exponential rule, which is defined by two specific parameters called length factor and spacing factor. The LPA is optimized for operation in 790-6000MHz frequency range, in order to cover the most usual wireless services in practice, and also to provide in this range the highest possible forward gain, gain flatness below 2dB, secondary lobe level below –20dB with respect to the main lobe peak, and standing wave ratio below 2. To demonstrate its superiority in terms of performance, PSOvm is compared to well-known optimization methods. The comparison is performed by applying all the methods on several test functions and also on the LPA optimization problem defined by the above-mentioned requirements. Furthermore, the radiation characteristics of the PSOvm-based LPA give prominence to the effectiveness of the proposed exponential geometry compared to the traditional Carrel’s geometry
Optical and structural characterization of Ge clusters embedded in ZrO2
Get PDFThe change of optical and structural properties of Ge nanoclusters in ZrO2 matrix have been investigated by spectroscopic ellipsometry versus annealing temperatures. Radio-frequency top-down magnetron sputtering approach was used to produce the samples of different types, i.e. single-layers of pure Ge, pure ZrO2 and Ge-rich-ZrO2 as well as multi-layers stacked of 40 periods of 5-nm-Ge-rich-ZrO2 layers alternated by 5-nm-ZrO2 ones. Germanium nanoclusters in ZrO2 host were formed by rapid-thermal annealing at 600-800 ∘C during 30 s in nitrogen atmosphere. Reference optical properties for pure ZrO2 and pure Ge have been extracted using single-layer samples. As-deposited multi-layer structures can be perfectly modeled using the effective medium theory. However, annealed multi-layers demonstrated a significant diffusion of elements that was confirmed by medium energy ion scattering measurements. This fact prevents fitting of such annealed structure either by homogeneous or by periodic multi-layer model
Managing housing needs of post conflict housing reconstruction:Sri Lankan perspective
No full textPurpose – Post conflict housing reconstruction is crucial to development and peacekeeping. However, the success of it, is hindered by a number of problems related to a lack of addressing housing needs.
The purpose of this paper is to explore how such housing needs can be effectively managed in post conflict housing reconstruction in Sri Lanka.
Design/methodology/approach – Using the grounded theory method as the research strategy, unstructured interviews were conducted with policy makers, practitioners, beneficiaries and academics in Sri Lanka. Data were analysed using open, axial and selective coding to develop the theoretical framework.
Findings – The study reveals the challenges, contributing factors and strategies in addressing housing needs of accessibility, habitability, affordability, location, facilities, cultural considerations and security of land tenure.
It also identifies the gaps and recommendations. The paper establishes the links between these and presents a theoretical framework formanaging housing needs effectively in post conflict housing reconstruction in Sri Lanka.
Practical implications – This research enhances the success of post conflict housing reconstruction through
addressing housing needs effectively, which contributes to sustainable housing development after conflicts.
Originality/value – The study combines the literature from five main areas: conflicts, post conflict,
post conflict reconstruction, post conflict housing reconstruction and housing needs and provides a better understanding on how the housing needs can be managed during post conflict housing reconstruction in developing countries based on empirical evidence.
Keywords- Housing, Customer satisfaction, Supervision, Construction management, Procurement, Conflict resolution
Paper type- Research pape
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