2,007 research outputs found

### When to invest in carbon capture and storage technology in the presence of uncertainty: a mathematical model. ESRI WP461, July 2013

We present a model for determining analytically the critical threshold for investment in carbon capture and storage technology in a region where carbon costs are volatile and assuming the cost of investment decreases. We first study a deterministic model with quite general dependence on carbon price and then analyse the effect of carbon price volatility on the optimal investment decision by solving a Bellman equation with an infinite planning horizon. We find that increasing the expected carbon price volatility increases the critical investment threshold and that adoption of this technology is not optimal at current prices, in agreement with other works. However, reducing carbon price volatility by switching from carbon permits to taxes or by introducing a carbon floor as in Great Britain would accelerate the optimal adoption of this technology. Our deterministic model provides a good description of this decision problem

### High speed video capture for mobile phone cameras

We consider an electromechanical model for the operation of a voice coil motor in a mobile phone camera, with the aim of optimizing how a lens can be moved to a desired focusing motion. Although a methodology is developed for optimizing lens shift, there is some concern about the experimentally-determined model parameters that are at our disposal. Central to the model is the value of the estimated magnetic force constant, Kf: its value determines how far it is actually possible to move lens, but it appears that, from the value given, it would not be possible to shift the lens through the displacements desired. Furthermore, earlier experiments have also estimated the value of the back EMF constant, Kg , to be roughly five times greater than Kf, even though we present two theoretical arguments that show that Kf = Kg: a conclusion supported by readily-available manufacturersâ data

### Predicting online product sales via online reviews, sentiments, and promotion strategies

Purpose
â The purpose of this paper is to investigate if online reviews (e.g. valence and volume), online promotional strategies (e.g. free delivery and discounts) and sentiments from user reviews can help predict product sales.
Design/methodology/approach
â The authors designed a big data architecture and deployed Node.js agents for scraping the Amazon.com pages using asynchronous input/output calls. The completed web crawling and scraping data sets were then preprocessed for sentimental and neural network analysis. The neural network was employed to examine which variables in the study are important predictors of product sales.
Findings
â This study found that although online reviews, online promotional strategies and online sentiments can all predict product sales, some variables are more important predictors than others. The authors found that the interplay effects of these variables become more important variables than the individual variables themselves. For example, online volume interactions with sentiments and discounts are more important than the individual predictors of discounts, sentiments or online volume.
Originality/value
â This study designed big data architecture, in combination with sentimental and neural network analysis that can facilitate future business research for predicting product sales in an online environment. This study also employed a predictive analytic approach (e.g. neural network) to examine the variables, and this approach is useful for future data analysis in a big data environment where prediction can have more practical implications than significance testing. This study also examined the interplay between online reviews, sentiments and promotional strategies, which up to now have mostly been examined individually in previous studies

### Distribution and density of the partition function zeros for the diamond-decorated Ising model

Exact renormalization map of temperature between two successive decorated
lattices is given, and the distribution of the partition function zeros in the
complex temperature plane is obtained for any decoration-level. The rule
governing the variation of the distribution pattern as the decoration-level
changes is given. The densities of the zeros for the first two
decoration-levels are calculated explicitly, and the qualitative features about
the densities of higher decoration-levels are given by conjecture. The Julia
set associated with the renormalization map is contained in the distribution of
the zeros in the limit of infinite decoration level, and the formation of the
Julia set in the course of increasing the decoration-level is given in terms of
the variations of the zero density.Comment: 8 pages,8figure

### Threshold concentration for H blistering in defect free W

Lattice distortion induced by high concentration of H is believed to be
precursor of H blistering in single crystalline W (SCW) during H isotope
irradiation. However, the critical H concentration needed to trigger
bond-breaking of metal atoms presents a challenge to measure. Using density
functional theory, we have calculated the formation energy of a vacancy and a
self-interstitial atom (SIA) in supersaturated defect-free SCW with various H
concentrations. When the ratio of H:W exceeds 1:2, the formation of both
vacancies and self-interstitials becomes exothermic, meaning that spontaneous
formation of micro-voids which can accommodate molecular H2 will occur.
Molecular H2 is not allowed to form, and it is not needed either at the very
initial stage of H blistering in SCW. With supersaturated H, the free volume at
the vacancy or SIA is greatly smeared out with severe lattice distortion and
more H can be trapped than in the dilute H case.Comment: 13 pages, 4 figure

### Achromat with linear space charge for bunched beams

The standard definition for an achromat is a transport line having zero values for the spatial dispersion (R16) and the angular dispersion (RZ6). For a bunched beam with linear space charge this definition of achromaticity does not hold. The linear space charge in the presence of a bend provides coupling between (a) bunch spatial width and bunch length (R1.5) and (b) bunch angular spread and bunch length (R25). Therefore, achromaticity should be redefined as a line having zero values of the spatial dispersion (R16), the angular dispersion (R26), and matrix elements R15 and R25. These additional conditions (R15=R25=0) can be achieved, for example, with two small RF cavities at appropriate locations in the achromat, to cancel space charge effects. An example of the application of this technique to the Spallation Neutron Source (SNS) high energy beam transport line is presented

### When to Invest in Carbon Capture and Storage Technology: A Mathematical Model. ESRI Research Bulletin 2014/1/4

The goal of this paper is to determine the optimal time to invest in retrofitting a CCS unit onto an existing power plant in (i) a region subject to a (deterministically evolving) carbon tax, such as the carbon floor introduced in Great Britain (GB) in April 2013, and (ii) in a region where there is uncertainty in the price o

### BFT embedding of noncommutative D-brane system

We study noncommutative geometry in the framework of the
Batalin-Fradkin-Tyutin(BFT) scheme, which converts second class constraint
system into first class one. In an open string theory noncommutative geometry
appears due to the mixed boundary conditions having second class constraints,
which arise in string theory with $D$-branes under a constant Neveu-Schwarz
$B$-field. Introduction of a new coordinate $y$ on $D$-brane through BFT
analysis allows us to obtain the commutative geometry with the help of the
first class constraints, and the resulting action corresponding to the first
class Hamiltonian in the BFT Hamiltonian formalism has a new local symmetry.Comment: 12 pages, no figure, some expressions corrected, to appear Phys. Rev.

### Next-to-Leading Order Cross Sections for Tagged Reactions

We extend the phase space slicing method of Giele, Glover and Kosower for
performing next-to-leading order jet cross section calculations in two
important ways: we show how to include fragmentation functions and how to
include massive particles. These extensions allow the application of this
method to not just jet cross sections but also to cross sections in which a
particular final state particle, including a $D$ or $B$-meson, is tagged.Comment: 36 pages, Latex Small corrections to text. To appear in Phys. Rev.

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