Gamow-Jordan Vectors and Non-Reducible Density Operators from Higher Order S-Matrix Poles

In analogy to Gamow vectors that are obtained from first order resonance poles of the S-matrix, one can also define higher order Gamow vectors which are derived from higher order poles of the S-matrix. An S-matrix pole of r-th order at z_R=E_R-i\Gamma/2 leads to r generalized eigenvectors of order k= 0, 1, ... , r-1, which are also Jordan vectors of degree (k+1) with generalized eigenvalue (E_R-i\Gamma/2). The Gamow-Jordan vectors are elements of a generalized complex eigenvector expansion, whose form suggests the definition of a state operator (density matrix) for the microphysical decaying state of this higher order pole. This microphysical state is a mixture of non-reducible components. In spite of the fact that the k-th order Gamow-Jordan vectors has the polynomial time-dependence which one always associates with higher order poles, the microphysical state obeys a purely exponential decay law.Comment: 39 pages, 3 PostScript figures; sub2.eps may stall some printers and should then be printed out separately; ghostview is o.

Casimir Invariants for Systems Undergoing Collective Motion

Dicke states are states of a collection of particles which have been under active investigation for several reasons. One reason is that the decay rates of these states can be quite different from a set of independently evolving particles. Another reason is that a particular class of these states are decoherence-free or noiseless with respect to a set of errors. These noiseless states, or more generally subsystems, can avoid certain types of errors in quantum information processing devices. Here we provide a method for calculating invariants of systems of particles undergoing collective motions. These invariants can be used to determine a complete set of commuting observables for a class of Dicke states as well as identify possible logical operations for decoherence-free/noiseless subsystems. Our method is quite general and provides results for cases where the constituent particles have more than two internal states.Comment: 5 page

Capture-ready power plants : options, technologies and economics

Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2006.Includes bibliographical references (p. 93-95).A plant can be considered to be capture-ready if, at some point in the future it can be retrofitted for carbon capture and sequestration and still be economical to operate. The concept of capture-ready is not a specific plant design; rather it is a spectrum of investments and design decisions that a plant owner might undertake during the design and construction of a plant. Power plant owners and policymakers are interested in capture-ready plants because they may offer relatively low cost opportunities to bridge the gap between current coal-fired generation technologies without CO2 capture to future plants that may be built from the start to capture CO2, and reduce the risks of possible future regulations of CO2 emissions. This thesis explores the design options, technologies and costs of capture-ready coal-fired power plants. The first part of the thesis outlines the two major designs that are being considered for construction in the near-term - pulverized coal (PC) and integrated gasification/combined cycle (IGCC). It details the steps that are necessary to retrofit each of these plants for CO2 capture and sequestration. Finally, for each technology, it provides a qualitative assessment of the steps that can be taken to reduce the costs and output de-rating of the plant after a retrofit.(cont.) The second part of the thesis evaluates the lifetime (40 year) net present value (NPV) costs of plants with differing levels of pre-investment for CO2 capture. Three scenarios are evaluated - a baseline supercritical PC plant, a baseline IGCC plant and an IGCC plant with pre-investment for capture. This analysis evaluates each technology option under a range of CO2 tax scenarios and determines the most economical choice and year of retrofit. The results of this thesis show that a baseline PC plant is the most economical choice under low CO2 tax rates, and IGCC plants are preferable at higher tax rates. Little difference is seen in the lifetime NPV costs between the IGCC plants with and without pre-investment for CO2 capture. The third part of this thesis evaluates the concept of CO2 "lock-in". CO2 lock-in occurs when a newly built plant is so prohibitively expensive to retrofit for CO2 capture that it will never be retrofitted for capture, and offers no economic opportunity to reduce the CO2 emissions from the plant, besides shutting down or rebuilding. The results of this analysis show that IGCC plants are expected to have significantly lower lifetime CO2 emissions than a PC plant, given moderate (10-35 $/ton CO2) initial tax rates.(cont.) Higher (above$40) or lower (below $7) initial tax rates do not result in significant differences in lifetime CO2 emissions from these plants. Little difference is seen in the lifetime CO2 emissions between the IGCC plants with and without pre-investment for CO2 capture.by Mark Bohm.S.M

Assessing issues of financing a CO2 transportation pipeline infrastructure

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Reliable and redundant FPGA based read-out design in the ATLAS TileCal Demonstrator

The Tile Calorimeter at ATLAS is a hadron calorimeter based on steel plates and scintillating tiles read out by PMTs. The current read-out system uses standard ADCs and custom ASICs to digitize and temporarily store the data on the detector. However, only a subset of the data is actually read out to the counting room. The on-detector electronics will be replaced around 2023. To achieve the required reliability the upgraded system will be highly redundant. Here the ASICs will be replaced with Kintex-7 FPGAs from Xilinx. This, in addition to the use of multiple 10 Gbps optical read-out links, will allow a full read-out of all detector data. Due to the higher radiation levels expected when the beam luminosity is increased, opportunities for repairs will be less frequent. The circuitry and firmware must therefore be designed for sufficiently high reliability using redundancy and radiation tolerant components. Within a year, a hybrid demonstrator including the new read-out system will be installed in one slice of the ATLAS Tile Calorimeter. This will allow the proposed upgrade to be thoroughly evaluated well before the planned 2023 deployment in all slices, especially with regard to long term reliability. Different firmware strategies alongside with their integration in the demonstrator are presented in the context of high reliability protection against hardware malfunction and radiation induced errors

Implications of Qudit Superselection rules for the Theory of Decoherence-free Subsystems

The use of d-state systems, or qudits, in quantum information processing is discussed. Three-state and higher dimensional quantum systems are known to have very different properties from two-state systems, i.e., qubits. In particular there exist qudit states which are not equivalent under local unitary transformations unless a selection rule is violated. This observation is shown to be an important factor in the theory of decoherence-free, or noiseless, subsystems. Experimentally observable consequences and methods for distinguishing these states are also provided, including the explicit construction of new decoherence-free or noiseless subsystems from qutrits. Implications for simulating quantum systems with quantum systems are also discussed.Comment: 13 pages, 1 figures, Version 2: Typos corrected, references fixed and new ones added, also includes referees suggested changes and a new exampl

Traffic related noise and air quality valuations: evidence from stated preference residential choice models

This paper reports on research which has estimated valuations of changes in traffic related noise levels and air quality and which contributes to the body of knowledge and to methodology in this area. There are several novel aspects of this research. Firstly, there have been relatively few stated preference studies of the monetary valuations of traffic related noise and air quality. A feature of this analysis is the examination of variations in values according to the size and sign of the environmental change, the currently experienced level of the attribute and various socio-economic factors. Secondly, the important issue of presentation is addressed, with two different methods used in the valuation of air quality and links made between valuations and physical measures. Thirdly, the results from stated preference and the contingent valuation method are compared. Finally, we bring together evidence from other studies and compare them with the findings obtained here

Coming down from the trees: is terrestrial activity in Bornean orangutans natural or disturbance driven?

The orangutan is the world's largest arboreal mammal, and images of the red ape moving through the tropical forest canopy symbolise its typical arboreal behaviour. Records of terrestrial behaviour are scarce and often associated with habitat disturbance. We conducted a large-scale species-level analysis of ground-based camera-trapping data to evaluate the extent to which Bornean orangutans Pongo pygmaeus come down from the trees to travel terrestrially, and whether they are indeed forced to the ground primarily by anthropogenic forest disturbances. Although the degree of forest disturbance and canopy gap size influenced terrestriality, orangutans were recorded on the ground as frequently in heavily degraded habitats as in primary forests. Furthermore, all age-sex classes were recorded on the ground (flanged males more often). This suggests that terrestrial locomotion is part of the Bornean orangutan's natural behavioural repertoire to a much greater extent than previously thought, and is only modified by habitat disturbance. The capacity of orangutans to come down from the trees may increase their ability to cope with at least smaller-scale forest fragmentation, and to cross moderately open spaces in mosaic landscapes, although the extent of this versatility remains to be investigated

Linear and nonlinear traveling edge waves in optical honeycomb lattices

Traveling unidirectional localized edge states in optical honeycomb lattices are analytically constructed. They are found in honeycomb arrays of helical waveguides designed to induce a periodic pseudomagnetic field varying in the direction of propagation. Conditions on whether a given pseudofield supports a traveling edge mode are discussed; a special case of the pseudofields studied agrees with recent experiments. Interesting classes of dispersion relations are obtained. Envelopes of nonlinear edge modes are described by the classical one-dimensional nonlinear Schrödinger equation along the edge. Nonlinear states termed edge solitons are predicted analytically and are found numerically

Comparison of Langmuir probe and laser Thomson scattering for electron property measurements in magnetron discharges

Electron property measurements made by Langmuir probe and laser Thomson scattering have been compared in weakly magnetized plasma conditions using a planar unbalanced magnetron with the aim of assessing the accuracy of the probe diagnostic. Measurements were performed at several locations within the magnetic field configuration; the magnetic null region (. 1 mT) on the discharge axis and inside the last closed flux surface boundary with fields up to 33 mT. There was good diagnostic agreement during High Power Impulse Magnetron Sputtering (HiPIMS) but significant discrepancies were observed for DC magnetron operation, even at the magnetic null. For some discharge conditions, the electron density determined by Thomson scattering was over an order of magnitude greater than the plasma density obtained from the Langmuir probe, using both ion and electron collection theories. In addition, the low energy part of the electron energy distribution function determined by the probe was depleted. The possible reasons for the discrepancies are discussed, with the conclusion being that the plasma was significantly perturbed by the probe stem. The range of plasma density and electron temperature measured in the study were 0.4-5.4 x 1017 m 3 and 0.2-5.9 eV, respectively