4,439 research outputs found
Control of construction costs during construction
The construction of a major project requires a vast amount of time, money, material and human resources. Proper coordination of these elements into an array of activities is crutial to the success of the project if it is to be built on time and within budget. As technology advances, the complexity of the project increases the resources to build them remain finite, and therefore, the project manager must seek methods to improve control on the construction project.
This thesis provides an overall view of the relatively new and rapidly expanding field of cost engineering. Cost engineering may be defined as that field of engineering practice where engineering judgement and experience are utilized in the application of science principles and techniques to the areas of cost estimation and cost control. Cost estimation and cost control will be the main subject of this thesis.
Although this area has tremendous impact on the economics of private industries and the goverment, cost estimating and cost control has usually underestimated. Virtually all decisions to construct a facility is based on economics, inturn, the economic study is based on the accuracy of an estimate. Once management has committed itself to the project, cost control protects its decision and holds expenditures within budget by constant monitoring and appraisal of cost performance of those responsible for executing the project.
The text will provide the reader with the basic understanding of the nature of construction costs, the types and importance of estimates, budgeting procedures and implementation of a cost control system
Towards microstructured optical fibre sensors: surface analysis of silanised lead silicate glass
While protocols to surface functionalise silica glass platforms are well-established, the surface coating of other glass types have received limited attention. Here we fully characterise the surface attachment of a fluoroionophore on extruded lead silicate glass slides and demonstrate these slides as a model for investigating the surface chemistry in a microstructured optical fibre (MOF). This model system allows the utilization of multiple, complementary surface-sensitive techniques that cannot be used within the internal surface of the fibre structure. In characterising the fluoroionophore attachment, we observe that the fluorescence intensity from fluorescence imaging, the atomic nitrogen percentage measured by X-ray photoelectron spectroscopy (XPS), the carbonyl bond component (287.5 eV) in the XPS high resolution carbon spectrum, and Principal Component Analysis (PCA) of the time-of-flight secondary ion mass spectrometry (ToF-SIMS) data can be used to provide relative quantification of the concentration of an attached fluoroionophore. We also show the first use of ToF-SIMS imaging and depth profiling of the Pb content within a glass substrate to provide information on the coverage provided by the coating and the relative thickness of an organic coating. Combined, these techniques provide a comprehensive picture of the coated glass surface that facilitates fibre sensor development.Herbert T. C. Foo, Heike Ebendorff-Heidepriem, Christopher J. Sumby, Tanya M. Monr
Charge-ordering, commensurability and metallicity in the phase diagram of layered Na(x)CoO(2)
The phase diagram of non-hydrated Na(x)CoO(2) has been determined by changing
the Na content x using a series of chemical reactions. As x increases from 0.3,
the ground state goes from a paramagnetic metal to a charge-ordered insulator
(at x=1/2) to a `Curie-Weiss metal' (around 0.70), and finally to a weak-moment
magnetically ordered state (x>0.75). The unusual properties of the state at 1/2
(including particle-hole symmetry at low T and enhanced thermal conductivity)
are described. The strong coupling between the Na ions and the holes is
emphasized.Comment: 4 pages with 3 figures, changed conten
Quasi-static Response of a Timoshenko Beam Loaded by an Elastically Supported Moving Rigid Beam
The present paper is concerned with the quasi-static response of an elastic beam, loaded by a rigid beam, which is slowly transported along the elastic beam. The elastic beam is modelled as a Timoshenko beam. The present paper provides a limiting case of the model with constant distributed load that is often considered in the study of transported masses. The rigid beam is connected to the Timoshenko beam by means of an interface modelled as a Winkler foundation. We present a non-dimensional study on the influence of the interface stiffness upon the displacement, bending moment and shear force of the Timoshenko beam, when the rigid beam is assumed to suffer a prescribed transverse displacement. Special emphasis is laid on the distribution of pressure transmitted by the interface between the Timoshenko beam and the rigid beam. Considerable pressure concentrations are found to take place and the locations of the maximum bending moments in the Timoshenko beam move towards the ends of the rigid beam
Interface relaxation in electrophoretic deposition of polymer chains: Effects of segmental dynamics, molecular weight, and field
Using different segmental dynamics and relaxation, characteristics of the
interface growth is examined in an electrophoretic deposition of polymer chains
on a three (2+1) dimensional discrete lattice with a Monte Carlo simulation.
Incorporation of faster modes such as crankshaft and reptation movements along
with the relatively slow kink-jump dynamics seems crucial in relaxing the
interface width. As the continuously released polymer chains are driven (via
segmental movements) and deposited, the interface width grows with the
number of time steps , (--,
which is followed by its saturation to a steady-state value . Stopping the
release of additional chains after saturation while continuing the segmental
movements relaxes the saturated width to an equilibrium value ().
Scaling of the relaxed interface width with the driving field , remains similar to that of the steady-state width. In
contrast to monotonic increase of the steady-state width , the relaxed
interface width is found to decay (possibly as a stretched exponential)
with the molecular weight.Comment: 5 pages, 7 figure
Improved Composite Table Algorithm for targeting regeneration-recycle water network
This work aims to improve the Composite Table Algorithm as a targeting tool for regeneration-recycle water network. It is demonstrated that some problems have the potential to achieve zero liquid discharge. A literature example on a petrochemical plant is used to show the applicability of the proposed method. MATLAB is utilised as a programming tool to facilitate the implementation of the developed method
23Na NMR study of non-superconducting double-layer hydrate NaxCoO2.yH2O
We report 23Na NMR studies of the polycrystalline samples of double-layer
hydrated cobalt oxides NaxCoO2.yH2O (x ~ 0.35 and y ~ 1.3) with the
superconducting transition temperatures Tc < 1.8K and ~4.5K, and the dehydrated
NaxCoO2 (x ~ 0.35). The hyperfine field and the electric field gradient at the
Na sites in the non-hydrated Na0.7CoO2 and the dehydrated Na0.35CoO2 are found
to be significantly reduced by the hydration, which indicates a strong
shielding effect of the intercalated water molecules on the Na sites. The
temperature dependence of 23 Na nuclear spin-lattice relaxation rate 1/23T1 of
the non-superconducting double-layer hydrate NaxCoO2.yH2O is found to be
similar to that of the non-hydrated Na0.7CoO2, whose spin dynamics is
understood by A-type (intra-layer ferromagnetic and inter-layer
antiferromagnetic) spin fluctuations. The superconducting phase is located
close to the quantum critical point with the A-type magnetic instability.Comment: 4 pages, 4 figure
Optical evidence for the proximity to a spin-density-wave metallic state in NaCoO
We present the optical properties of \na single crystals, measured over a
broad spectral range as a function of temperature (). The capability to
cover the energy range from the far-infrared up to the ultraviolet allows us to
perform reliable Kramers-Kronig transformation, in order to obtain the
absorption spectrum (i.e., the complex optical conductivity). To the complex
optical conductivity we apply the generalized Drude model, extracting the
frequency dependence of the scattering rate () and effective mass
() of the itinerant charge carriers. We find that at low temperatures and for . This suggests that \na is at
the verge of a spin-density-wave metallic phase
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