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A semi-analytical beam model for the vibration of railway tracks
Get PDFThe high frequency dynamic behaviour of railway tracks, in both vertical and lateral directions, strongly affects the generation of rolling noise as well as other phenomena such as rail corrugation. An improved semi-analytical model of a beam on an elastic foundation is introduced that accounts for the coupling of the vertical and lateral vibration. The model includes the effects of cross-section asymmetry, shear deformation, rotational inertia and restrained warping. Consideration is given to the fact that the loads at the rail head, as well as those exerted by the railpads at the rail foot, may not act through the centroid of the section. The response is evaluated for a harmonic load and the solution is obtained in the wavenumber domain. Results are presented as dispersion curves for free and supported rails and are validated with the aid of a Finite Element (FE) and a waveguide finite element (WFE) model. Closed form expressions are derived for the forced response, and validated against the WFE model. Track mobilities and decay rates are presented to assess the potential implications for rolling noise and the influence of the various sources of vertical-lateral coupling. Comparison is also made with measured data. Overall, the model presented performs very well, especially for the lateral vibration, although it does not contain the high frequency cross-section deformation modes. The most significant effects on the response are shown to be the inclusion of torsion and foundation eccentricity, which mainly affect the lateral response
Charge-transfer dynamics at the dye-semiconductor interface of photocathodes for solar energy applications
No full textThis article describes a comparison between the photophysical properties of two charge-transfer dyes adsorbed onto NiO via two different binding moieties. Transient spectroscopy measurements suggest that the structure of the anchoring group affects both the rate of charge recombination between the dye and NiO surface and the rate of dye regeneration by an iodide/triiodide redox couple. This is consistent with the performance of the dyes in p-type dye sensitised solar cells. A key finding was that the recombination rate differed in presence of the redox couple. This has important implications on the study of electron transfer at dye|semiconductor interfaces for solar energy applications
A consideration of Boundary Objects as a means of Integrating Design and Construction – A Case Study
No full textIntegration between Design and Construction is a common topic discussed in the literature in construction. The impacts of construction industry fragmentation are quite well known: poor design quality, lack of standards and constructability, suboptimal design solutions, high number of change orders, high rate of rework in design and construction, low value delivered for clients, design and construction delays and higher project costs. In the case of construction projects in which the design stage overlaps the construction stage, the industry fragmentation increases the projects’ risks and in some cases it nullifies the gains in cost and time which come about when using the strategy of overlapping.
Although researchers tried to address the problem of industry fragmentation by implementing new tools and methods to integrate project stakeholders, for example, using Building Information Modelling (BIM), Integrated Concurrent Engineering, Big-Room, and so on, the literature is still lacking in concepts and theories about how to integrate planning and controlling of both Design and Construction stages.
The purpose of this paper is to present the use of some concepts, such as production batch and work package, in order to create a common ground among Design, Construction and Costs simulations using BIM and line of balance. The case study is a retrofit of a set of social housing in Antrim (Northern Ireland) which aims to improve the energy efficiency of solid wall houses, at the sametime as reducing the disruption for end users. The study is part of the research project entitled S-IMPLER (Solid Wall Innovative Insulation and Monitoring Processes using Lean Energy Efficient Retrofit) funded by the Innovate UK, which aims to develop a retrofit solution for social housing built with solid walls to achieve 60% reduction in monitored energy costs, with less disruption for end users, keeping quality and safety at high levels.
The use of these concepts allowed the creation of different scenarios for design solutions and production system organization which were presented in a What-if Matrix. The costs changed as a consequence of the crossing scenarios. Adding to it, the definition of production batch and work package was essential to develop the BIM models (3D, 4D and 5D), as well as the line of balance used to plan the retrofit works and measure the end users disruption.
The research findings show that the common definition of production batch and work packages between Design and Construction stages used in the retrofit study worked as a boundary object in the development of BIM models and scenarios simulations. These concepts created the basis for the integration between design and construction, especially, in projects using BIM.
The results are not limited to the context of retrofit and further research is currently undertaken by the researchers to examine its validity and applicability in different settings.
Keywords: BIM; Line of Balance; integration design and constructio
Maybe having a billionaire mogul as president in Trump isn't so bad?
No full textTrump needs re-understanding through an academic lens, avoiding the frenzy of media interpretation
Bis-Picolinamide ruthenium (III) dihalide complexes: dichloride to diiodide exchange generates single trans isomers with high potency and cancer cell selectivity
Get PDFA library of new bis-picolinamide ruthenium(III) dihalide complexes of the type RuX2L2 (X = Cl or I and L = picolinamide) have been synthesized and characterized. They exhibit different picolinamide ligand binding modes, whereby one ligand is bound (N,N) and the other bound (N,O). Structural studies reveal a mixture of cis and trans isomers for the RuCl2L2 complexes but upon a halide exchange reaction to RuI2L2, only single trans isomers are present. High cytotoxic activity against human cancer cell lines was observed, with potencies for some complexes similar to or better than cisplatin. Conversion to RuI2L2 substantially increased activity towards cancer cell lines by >12-fold. The RuI2L2 complexes displayed potent activity against the A2780cis (cisplatin-resistant human ovarian cancer) cell line, with >4-fold higher potency than cisplatin. Equitoxic activity was observed against normoxic and hypoxic cancer cells, indicating potential to eradicate both the hypoxic and aerobic fractions of solid tumours with similar efficiency. Selected complexes were also tested against non-cancer ARPE-19 cells. The RuI2L2 complexes are more potent than the RuCl2L2 analogues, and also more selective towards cancer cells with a selectivity factor >7-fol
Areal surface measurement using multidirectional laser line scanning
No full textThe overall quality of a machined component has an important association with
the quality of its surface finish. To obtain adequate data for the surface metrology
of machined components, areal scanners are often preferred over stylus based
profile scanners due to their ability to acquire surface data over a relatively large
area. To further improve efficiency, there is a desire to perform on-machine
measurement, and recently, high-resolution areal surface scanners have been
integrated as an on-machine measurement device. Due to the limited areal
coverage, these scanners can require multiple scans to capture data from surfaces
produced on machine tools which requires a sufficient amount of time to
complete a full surface scan. In addition, since these scanners are very sensitive,
scanning delays often cause areal scanners to capture data contaminated with
noise which may arise from within the machining environment such as axes
vibrations, temperature effects, dust, etc. These factors mean such instruments
are typically used in metrology laboratories.
This paper presents a new methodology referred to as multidirectional
scanning (MDS) which is a technique that exploits characteristics of a 2D laser
line scanner (profilometer). The device is used in two directions to scan the
overall component surface ensuring the coverage of a wider surface area
compared to typical areal scanners. Since the scanner is robust and integrated
onto a machine tool, controlled axes feed rates in the orthogonal directions
ensure high spatial resolution which in turn helps to identify and reduce the noise
levels in the data. This methodology has been validated to be both accurate and
rapid to scan the component surface, reducing the cost associated with machine
downtime and also having a wider coverage of 6x6 mm2 for a single scan,
compared to 1 mm2 for most conventional areal surface measurement
instruments having comparable spatial and vertical resolution
Non-epileptic attack disorder: the importance of diagnosis and treatment
No full textA 50-year-old woman was taken to hospital by emergency ambulance during her first seizure. She was admitted to hospital, treated with intravenous diazepam, diagnosed with epilepsy and started on antiepileptic drug (AED) therapy. This was ineffective so she was referred to a tertiary centre where she underwent video EEG and was diagnosed with non-epileptic attack disorder. Her experience of the diagnosis was positive; it allowed her to understand what was happening to her and to understand the link between her seizures, adverse childhood experiences and the death of her mother. She stopped taking AEDs and she was referred to a psychologist which led to a significant improvement in her functioning and quality of life. We present this case as a good example of the benefits of accurate diagnosis, clear explanation and access to specialist car
Synthesis, Structural and Biological Studies of Some Half-Sandwich d6-Metal Complexes with Pyrimidine-Based Ligand
No full textThe reaction of metal precursors {[Cp*MCl2]2 (M=Rh, Ir)} with 2-
aminopyrimidine (L1) gave binuclear complexes as [(Cp*MCl2)2
(m-L1)], where L1 acted as a bridging ligand. While 2-
mercaptopyrimidine (L2) with [Cp*MCl2]2 {M=Rh(III), Ir(III)}
formed mononuclear di substituted complexes as [Cp*M(L2)2],
where L2 acted as a chelating as well as a monodentate ligand.
The reaction of [CpRu(PPh3)2Cl] with 2-mercaptopyrimidine (L2)
led to the formation of mononuclear complex as general
formula [CpRu(PPh3)(L2)] in presence of a base. 2-Mercaptopyrimidine
ligand resulted complexes with strained four-membered
metallacycle while 2-aminopyrimidine yielded bridged
complexes. HOMO-LUMO energy gaps and UV-Visible bands
were additionally rationalised by the DFT studies. The binding
ability of the complexes to the CT-DNA was confirmed using
UV-Visible and fluorescence spectroscopy. In vitro antibacterial
activity of the complexes was evaluated against human
pathogenic bacteria. Cytotoxicity of the complexes was examined
by the MTT assay over three cancerous and one noncancer
cell lines viz., BE, HT-29, MIA@Pa-Ca2 and ARPE-19
Ecological risk assessment of agricultural soils for the definition of soil screening values: A comparison between substance-based and matrix-based approaches
No full textThe Italian legislation on contaminated soils does not include the Ecological Risk Assessment (ERA) and this deficiency has important consequences for the sustainable management of agricultural soils. The present research compares the results of two ERA procedures applied to agriculture (i) one based on the “substance-based” approach and (ii) a second based on the “matrix-based” approach. In the former the soil screening values (SVs) for individual substances were derived according to institutional foreign guidelines. In the latter, the SVs characterizing the whole-matrix were derived originally by the authors by means of experimental activity.
The results indicate that the “matrix-based” approach can be efficiently implemented in the Italian legislation for the ERA of agricultural soils. This method, if compared to the institutionalized “substance based” approach is (i) comparable in economic terms and in testing time, (ii) is site specific and assesses the real effect of the investigated soil on a battery of bioassays, (iii) accounts for phenomena that may radically modify the exposure of the organisms to the totality of contaminants and (iv) can be considered sufficiently conservative
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