2,100 research outputs found
Polymer multimode waveguide optical and electronic PCB manufacturing
No full textThe paper describes the research in the £1.3 million IeMRC Integrated Optical and Electronic Interconnect PCB Manufacturing (OPCB) Flagship Project in which 8 companies and 3 universities carry out collaborative research and which was formed and is technically led by the author. The consortium’s research is aimed at investigating a range of fabrication techniques, some established and some novel, for fabricating polymer multimode waveguides from several polymers, some formulations of which are being developed within the project. The challenge is to develop low cost waveguide manufacturing techniques compatible with commercial PCB manufacturing and to reduce their alignment cost. The project aims to take the first steps in making this hybrid optical waveguide and electrical copper track printed circuit board disruptive technology widely available by establishing and incorporating waveguide design rules into commercial PCB layout software and transferring the technology for fabricating such boards to a commercial PCB manufacturer. To focus the research the project is designing an optical waveguide backplane to tight realistic constraints, using commercial layout software with the new optical design rules, for a demonstrator into which 4 daughter cards are plugged, each carrying an aggregate of 80 Gb/s data so that each waveguide carries 10 Gb/s
var. grindelioides
No full textXanthisma grindelioides (Nuttall) D.R. Morgan & R.L. Hartman var. grindelioidesHaplopappus nuttalliiLost River valley, 10 mi W Wild Horse Customs, SW facing slope on side of valleyfine sand
The Distribution of PGE and the Role of Arsenic as a Collector of PGE in the Spotted Quoll Nickel Ore Deposit in the Forrestania Greenstone Belt, Western Australia
No full textThe Spotted Quoll PGE-bearing Ni deposit in the Forrestania greenstone belt in the Archean Yilgarn block in Western Australia is a komatiite-associated massive sulfide orebody tectonically displaced from its original host. The brecciated ore contains clasts of quartz and garnet schist and is located along a shear zone overlain by banded iron formation (BIF) and underlain by BIF and quartz-biotite metasediments. The deformation of the ore has destroyed its magmatic textures and it has been sheared and recrystallized at amphibolite facies. Then the deformed ore has been subjected to a hydrothermal event that concentrated the PGE with Au and As, often at the edge of the Ni ore. The PGE are distributed between PGM and in solid solution in Ni sulfarsenides, and Pd also occurs in pentlandite. The PGM include sudburyite (PdSb), sperrylite (PtAs2), and irarsite (IrAsS). All six PGE and minor Au are hosted in gersdorffite (NiAsS). Two generations of gersdorffite have been recognized. A higher temperature magmatic euhedral Co-rich gersdorffite encloses Ir-, Pt- and Rh-bearing PGM surrounded by halos of Rh-, Ir-, and Os-rich gersdorffite. A lower temperature Ni-rich gersdorffite forms anhedral grains and rims on grains of nickeline (NiAs). In this low-temperature gersdorffite PGE are concentrated toward the mineral edges. Sudburyite and gold occur associated predominantly with nickeline. The PGE and gold are now predominantly associated with sulfarsenides that are the controlling factor for their distribution
Intra-annual and intra-seasonal flow dynamics of a High Arctic polythermal valley glacier
No full textMeasurements of surface dynamics on polythermal John Evans Glacier, Nunavut, Canada, over two winter periods and every 7-10 days throughout two melt seasons (June-July 2000, 2001) provide new insight into spatio-temporal patterns of High Arctic glacier dynamics. In the lower ablation zone, mean annual surface velocities are 10-21m a-1, but peak velocities up to 50% higher are attained during late June/early July. In the upper ablation zone and lower accumulation zone, mean annual surface velocities are typically 10-18 m a-1, and peak velocities up to 40% higher occur during late July. In the upper accumulation zone, mean annual surface velocities are 2-9 m a-1, and motion in mid- to late July exceeds this by up to 10%. Rapid drainage of ponded supraglacial water in the upper ablation zone to an initially distributed subglacial drainage system in mid-June may force excess surface motion in the warm-based lower glacier. The data indicate that the duration of the velocity response may be related to the rate of channelization of the basal drainage, and the velocity response may be transmitted up-glacier by longitudinal coupling. An increase in surface velocities in the middle glacier in late July occurs in conjunction with the opening of two further moulins in the accumulation zone
The Chance and Probability Concepts Project
No full textThis article, created by D.R. Green, describes an investigation of what concepts and intuitions concerning random processes are present in the minds of children of varying abilities across the 11-16 age range. The ability to list permutations, combinations and arrangements is also being investigated. The author states, "Over the past two decades the topic of 'Probabilityâ has been brought into the mathematics curriculum but it may be that this is more an empty gesture rather than a sound strategy." This article can help to alleviate many of the struggles in teaching probability concepts. The article is pitched at a more elementary audience, but is still a perfect resource for almost anyone teaching in the field
Achieving 10 ps coincidence time resolution in TOF-PET is an impossible dream
No full textGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.RST/Radiation, Science and TechnologyRST/Medical Physics & Technolog
An implicit algorithm for capturing sharp fluid interfaces in the volume of fluid advection method
No full textThe Volume of Fluid (VOF) method is one of the most effective methods employed in the simulation of two fluid flows with interfaces where density and viscosity change abruptly. These interfaces are represented implicitly by the values of a colour function which is a volume fraction of one of the fluids. The advantage of the method is its ability to deal with arbitrarily shaped interfaces and to cope with large deformations, as well as interface rupture and coalescence in a natural way. In comparison to a level set method, the mass is rigorously conserved in VOF, provided the discretisation is conservative, but one of the main difficulties is advecting the interface without diffusing, dispersing, or wrinkling it. This can either be performed algebraically, in schemes such as CICSAM or geometrically, in schemes such as PLIC. In the present paper, an algebraic advection scheme for the interface is presented, which is designed for the implicit time advancing algorithm. Analogous to CICSAM, the new scheme switches smoothly between ULTIMATE-QUICK and the upper bound of the universal limiter, depending on the angle between the interface and the flow direction. Four cases are tested with the present scheme: (i) solid body rotation; (ii) circle in a shear flow; (iii) dam-break and (iv) Rayleigh-Taylor instability. In the first two test cases, prescribed velocity fields are used, thereby allowing the effectiveness of the scheme in advecting the colour function only to be assessed. The scheme is found to outperform six other methods used for comparison in both studies. In solid body rotation simulations a fractional error of 0.19% is calculated in comparison to the next best recorded error of 1.1%. Similarly, in the longest shear flow simulation, a fractional error of 1.2% is calculated in comparison to the next best recorded error of 3.9%. In the final two test cases the advection equation for the colour function is coupled to the Navier-Stokes equations. In dam-break simulations it is found that the resulting solution effectively captures the trends displayed in experimental data for the advancing water front and the residual height of the liquid column against time. Qualitative results obtained for the Rayleigh-Taylor instability modelling in test case four are found to compare favourably to previous numerical simulations of the same phenomenon
Microstructural modelling of creep crack growth from a blunted crack
No full textThe effect of crack tip blunting on the initial stages of creep crack growth is investigated by means of a planar microstructural model in which grains are represented discretely. The actual linking-up process of discrete microcracks with the macroscopic crack is simulated, with full account of the underlying physical mechanisms such as the nucleation, growth and coalescence of grain boundary cavities accompanied by grain boundary sliding. Results are presented for C*-controlled mode I crack growth under small-scale damage conditions. Particular attention is focused on creep constrained vs. unconstrained growth. Also the effect of grain boundary shear stresses on linking-up is investigated through shear-modified nucleation and growth models. The computations show a general trend that while an initially sharp crack tends to propagate away from the original crack plane, crack tip blunting reduces the crack growth direction. Under unconstrained conditions this can be partly rationalized by the strain rate and facet stress distribution corresponding to steady-state creep.
Bepalen van het massatraagheidsmoment met behulp van een bifilar pendulum: Determining the moments of inertia using a bifilar pendulum
No full textThe aim of this thesis is to investigate the use of a bifilar pendulum for determining the moments of inertia of the TU Delft solar boat and to quantitatively predict the estimates. In the first part, several methods are discussed which can be applied in deriving the equations of motion of the pendulum. A new method, Kane's method, will be introduced. In the second part, this method will be used to derive the actual equations of motion. These equations are linearized around of the the pendulum's stationary positions to obtain expressions which link the moment of inertia about an axis to the period of oscillation of the pendulum about that axis. These equations are subsequently applied to the solar boat to derive estimates for the moments of inertia about the principle axis of the boat. The results of this thesis considers three different configurations of the bifilar pendulum with the solar boat suspended. One of these configurations results in the most accurate estimates for the moments of inertia, however, these have not been quantitatively predicted. The author suggests a modification in the definition of the bifilar pendulum such that this might be possible.Electrical Engineering, Mathematics and Computer ScienceNumerical analysi
An introduction to management science: quantitative approaches to decision making
No full textRetaining the accessible application-driven approach for which An Introduction to Management Science is highly regarded, adapting author Mik Wisniewski has carefully reworked the existing US textbook to benefit students across the UK, Europe, Middle East and Africa. Packed with diverse realistic examples from Scotland to Saudi Arabia, the landmark text from the ASW team is now available in a truly internationalised version for students studying Management Science and Operations Research at postgraduate and undergraduate level
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