3,153 research outputs found
Low temperature alteration carbonates in the ocean crust and their importance for CO2 uptake and the global Ca cycle
Development of a fiber optic high temperature strain sensor
From 1 Apr. 1991 to 31 Aug. 1992, the Georgia Tech Research Institute conducted a research program to develop a high temperature fiber optic strain sensor as part of a measurement program for the space shuttle booster rocket motor. The major objectives of this program were divided into four tasks. Under Task 1, the literature on high-temperature fiber optic strain sensors was reviewed. Task 2 addressed the design and fabrication of the strain sensor. Tests and calibration were conducted under Task 3, and Task 4 was to generate recommendations for a follow-on study of a distributed strain sensor. Task 4 was submitted to NASA as a separate proposal
Markets versus Regulation: The Efficiency and Distributional Impacts of U.S. Climate Policy Proposals
Regulatory measures have proven the favored approach to climate change mitigation in the U.S., while market-based policies have gained little traction. Using a model that resolves the U.S. economy by region, income category, and sector-specific technology deployment opportunities, this paper studies the magnitude and distribution of economic impacts under regulatory versus market-based approaches. We quantify heterogeneity in the national response to regulatory policies, including a fuel economy standard and a clean or renewable electricity standard, and compare these to a capâandâtrade system targeting carbon dioxide or all greenhouse gases. We find that the regulatory policies substantially exceed the cost of a capâandâtrade system at the national level. We further show that the regulatory policies yield large cost disparities across regions and income groups, which are exaggerated by the difficulty of implementing revenue recycling provisions under regulatory policy designs.We acknowledge support of the MIT Joint Program on the Science and Policy of Global Change through a combination of government, industry, and foundation funding, the MIT Energy Initiative, and additional support for this work from a coalition of industrial sponsors. This work is also supported by the DOE Integrated Assessment Grant (DE-FG02-94ER61937). For development of the USREP-ReEDS model, the authors further acknowledge the support of the Joint Institute for Strategic Energy Analysis, which is operated by the Alliance for Sustainable Energy, LLC, on behalf of the U.S. Department of Energyâs National Renewable Energy Laboratory, the University of Colorado-Boulder, the Colorado School of Mines, the Colorado State University, the Massachusetts Institute of Technology, and Stanford University
Fractional Supersymmetry and Fth-Roots of Representations
A generalization of super-Lie algebras is presented. It is then shown that
all known examples of fractional supersymmetry can be understood in this
formulation. However, the incorporation of three dimensional fractional
supersymmetry in this framework needs some care. The proposed solutions lead
naturally to a formulation of a fractional supersymmetry starting from any
representation D of any Lie algebra g. This involves taking the Fth-roots of D
in an appropriate sense. A fractional supersymmetry in any space-time dimension
is then possible. This formalism finally leads to an infinite dimensional
extension of g, reducing to the centerless Virasoro algebra when g=sl(2,R).Comment: 23 pages, 1 figure, LaTex file with epsf.st
Extended Complex Trigonometry in Relation to Integrable 2D-Quantum Field Theories and Duality
Multicomplex numbers of order n have an associated trigonometry (multisine
functions with (n-1) parameters) leading to a natural extension of the
sine-Gordon model. The parameters are constrained from the requirement of local
current conservation. In two dimensions for n < 6 known integrable models
(deformed Toda and non-linear sigma, pure affine Toda...) with dual
counterparts are obtained in this way from the multicomplex space MC itself and
from the natural embedding \MC_n \subset \MMC_m, n < m. For a
generic constraint on the space of parametersis obtained from current
conservation at first order in the interaction Lagragien.Comment: 11 pages, no figure, LaTex with amsmath accepted by Phys. Lett.
Calculation of AGARD Wing 445.6 Flutter Using Navier-Stokes Aerodynamics
An unsteady, 3D, implicit upwind Euler/Navier-Stokes algorithm is here used to compute the flutter characteristics of Wing 445.6, the AGARD standard aeroelastic configuration for dynamic response, with a view to the discrepancy between Euler characteristics and experimental data. Attention is given to effects of fluid viscosity, structural damping, and number of structural model nodes. The flutter characteristics of the wing are determined using these unsteady generalized aerodynamic forces in a traditional V-g analysis. The V-g analysis indicates that fluid viscosity has a significant effect on the supersonic flutter boundary for this wing
Capturing Natural Resource Dynamics in Top-Down EnergyâEconomic Equilibrium Models
Top-down energy-economic modeling approaches often use deliberately simple techniques to represent heterogeneous resource inputs to production. We show that for some policies, such as feed-in tariffs (FIT) for renewable electricity, detailed representation of renewable resource grades is required to describe the technology more precisely and identify cost-effective policy designs. We extend a hybrid approach for modeling heterogeneity in the quality of natural resource inputs required for renewable energy production in a stylized computable general equilibrium (CGE) framework. Importantly, this approach resolves nearflat or near-vertical sections of the resource supply curve that translate into key features of the marginal cost of wind resource supply, allowing for more realistic policy simulation. In a second step, we represent the shape of a resource supply curve based on more detailed data. We show that for the case of onshore wind development in China, a differentiated FIT design that can only be modeled with the hybrid approach requires less than half of the subsidy budget needed for a uniform FIT design and proves to be more cost-effective.This work was supported by Eni S.p.A., ICF International, the French Development Agency
(AFD), and Shell, founding sponsors of the MIT-Tsinghua China Energy and Climate Project. We
are further thankful for support provided by the MIT Joint Program on the Science and Policy of
Global Change through a consortium of industrial sponsors and U.S. federal grants. In particular,
this work was supported by the DOE Integrated Assessment Grant (DE-FG02-94ER61937)
Radical Prostatectomy: An Option for High-Risk Prostate Cancer
Introduction. High-risk prostate cancer represents a therapeutic challenge. The role of radical prostatectomy (RP) in patients with extreme PSA values is under discussion. Material and Methods. We retrospectively analysed our data of 56 consecutive patients with preoperative PSA â„ 40âmg/mL undergoing open radical retropubic prostatectomy from 1999 to 2009. Patient survival and time to PSA recurrence were recorded, and the Kaplan-Meier survival analysis was performed. Postoperative quality of life and functional status were investigated using a SF-12 questionnaire and determining the number of pads used per day. Results. Overall 56 patients were available for followup after a median time of 83.84 months. Locally advanced carcinoma was present in 84% while 16% of patients had organ-confined stages. A positive nodal status was observed in 46%. Overall survival was 95% at five and
81% at 10 years. Cancer-specific survival was 100% for five years and 83% for 10 years. Corresponding biochemical recurrence-free survival was low (52% and 11%,
resp.). Quality of life and functional outcomes were favourable. Conclusions. In patients with PSA â„ 40âmg/mL, RP allows long-term control, exact planning of adjuvant treatment, and identification of curable disease
Unexpected Features of Supersymmetry with Central Charges
It is shown that N=2 supersymmetric theories with central charges present
some hidden quartic symmetry. This enables us to construct representations of
the quartic structure induced by superalgebra representations.Comment: 14 pages, more details have been given, to appear in J. Phys.
Transaction Support for DataWeb Applications - A Requirement\u27s Perspective
W eb-based purely providing read-only access to information in terms of static HTML pages. Rather, more and more web-based information systems store (part of) the information within a database system (DBS) and generate HTML pages on demand. Such information systems are often called DataWeb Applications. Different users interact with the system, and often they perform changes concurrently. As an example in the area of electronic commerce, consider a web-based tourism information system, where an unpredictable number of a priori unknown tourists are allowed to book various tourism facilities at the same time. Whereas financial and security issues of such electronic commerce transactions are extensively discussed in literature, very few work exists on the database transaction aspect in terms of consistency and reliability of electronic commerce transactions and of DataWeb applications in general. The objective of this paper is to discuss the specific requirements that different architectures of DataWeb applications and the web itself pose on transaction management, and to identify promising technologies for enabling web transaction services
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