walter russell mead: Topics by WorldWideScience.org

A monograph of the genus Casuarius / by Walter Rothschild ; with a dissertation on the morphology and phylogeny of the ...

Not Available

2000-03-01

Language: English ...

Life of the stars

Plant communities of a Central Namib inselberg landscape

Stars and star evolution are discussed, including supernovae, nucleosynthesis, and mass-luminosity and Hertzsprung--Russell diagrams./aip/.

1988-09-20

Implementation of an Intravenous/Phlebotomy Team at Walter ...

... National Atlas of South West Africa. National Bookprinters, Goodwood, ZA. Walter, H. 1986. The Namib Desert. In: ... ...

A Composite Architecture for Network Security at JPL Robert B ...

... dressing changes and site care, mid-line placement, placement of peripherally inserted central catheters, heparin locks, and patient education. ...

1993-08-01

Single and binary star evolution

A Composite Architecture for Network Security at JPL. Robert B. Mead, Tom G. Dearmond, and Joseph S. Sherif. JPL, California Institute of Technology ...

Global climate change response program. Part 1. Potential effects of global change on chlorophyll alpha concentrations in a southwestern desert reservoir: Las Vegas Bay, Lake Mead, Nevada. Part 2. Simulated impacts of a double CO2 climate on the location of the thermocline in Lake Mead, Nevada. Final report

After presenting a general account of the observed global properties of single stars of low, intermediate, and high mass, together with their theoretical Hertzsprung-Russell diagram evolution, attention is given to the observed properties of various evolved close binaries and to an assessment of the value of comparisons between observation and crude theory in characterizing the physics of mass transfer within interacting binary systems. Detailed consideration is then undertaken of such topics as stellar evolution in globular clusters, interior star changes due to nucleosynthesis and mixing, asymptotic giant branch stars of intermediate mass, the response of white dwarfs in binary systems to mass accretion, and scenarios for binary star evolution tending toward close white dwarf pairs.

Reply to comment on "A simple model for the short-time evolution of near-surface current and temperature profiles"

Three algal bioassay experiments were conducted from March 1992 through September 1993 in an area of Lake Mead that has experienced problems associated with severe nutrient enrichment. The first experiment determined the effects of elevated CO2 (700 ppm) (2xCO2), vs ambient CO2 on the natural algal assemblage without nutrient enrichment. The second experiment determined the effects of 2xCO2 on nutrient enriched bioassays and if nutrients were limiting. The third experiment examined elevated temperatures and 2xCO2. Nested climate models were used to predict changes in water temperatures and thermocline development in Las Vegas Bay. The lake model predicted an increase in mean water temperatures of 1.8 deg under a 2xCO2 scenario. A thermocline definition of 1 deg. C change per 2-m depth was applied to water temperatures developed by a lake model coupled to nested general circulation and regional-scale atmospheric models in 3-year simulations of the current and ...

1997-01-01

CERN Document Server

This is our response to a comment by Walter Eifler on our paper `A simple model for the short-time evolution of near-surface current and temperature profiles' (arXiv:physics/0503186, accepted for publication in Deep-Sea Research II). Although Eifler raises genuine issues regarding our model's validity and applicability, we are nevertheless of the opinion that it is of value for the short-term evolution of the upper-ocean profiles of current and temperature. The fact that the effective eddy viscosity tends to infinity for infinite time under a steady wind stress may not be surprising. It can be interpreted as a vertical shift of the eddy viscosity profile and an increase in the size of the dominant turbulent eddies under the assumed conditions of small stratification and infinite water depth.

2005-01-01

Russell Group: Sitemap

Wastenet

...motion - Oxford Low carbon power - Imperial Oil exploration - Edinburgh Better policing - Leeds Efficient aircraft - Bristol Pioneering Drug Delivery - Nottingham Plastic electronics - Cambridge Materials discovery - Liverpool Bioluminescence - Cardiff Sucralose - King's Intellectual property - LSE Aeroengine repair - Birmingham Anti-viral drugs - UCL Marine engineering skills - Southampton Business Management - Warwick Medical imaging - Imperial Biopharmaceutical skills - Newcastle Primary education - Queen's Ultrafast Computing - Glasgow Clinical Development Centre - Kings Clean fuels at Oxford DNA sequencing - Cambridge 3G phone auctions - UCL Drugs and health screening - Leeds Business and Community Innovation Graduates Training and professional development Members Download a ...

Potential-Based Shaping and Q-Value Initialization are Equivalent

CERN Document Server

Shaping has proven to be a powerful but precarious means of improving reinforcement learning performance. Ng, Harada, and Russell (1999) proposed the potential-based shaping algorithm for adding shaping rewards in a way that guarantees the learner will learn optimal behavior. In this note, we prove certain similarities between this shaping algorithm and the initialization step required for several reinforcement learning algorithms. More specifically, we prove that a reinforcement learner with initial Q-values based on the shaping algorithm's potential function make the same updates throughout learning as a learner receiving potential-based shaping rewards. We further prove that under a broad category of policies, the behavior of these two learners are indistinguishable. The comparison provides intuition on the theoretical properties of the shaping algorithm as well as a suggestion for a simpler method for capturing the algorithm's benefit. In addition, the ...

2011-01-01

Optimization of band gap of photonic crystals fabricated by holographic lithography

Dynamic optimization of the benzene extractive distillation unit

Generally the photonic band gap (PBG) is a multi-variable function of several parameters related to the shape and size of the dielectric columns of photonic crystals (PhCs), and a time-consuming step-by-step scanning process for each parameter has to be used to find their best combination yielding maximum PBG. In this letter, the widely used Nelder-Mead simplex algorithm is introduced to optimize these parameters simultaneously to find a larger PBG for a new kind of two-dimensional (2D) hexagonal GaAs-Air PhC. This structure can be conveniently produced by the single-exposure holographic lithography, and the specific holographic design is also systematically investigated. This study reveals that the band gaps of PhCs made by holographic lithography may be widened by introducing irregularity of the columns and lowering the symmetry of the structure.

2008-01-01

Scientific Electronic Library Online (English)

Abstract in english A mathematical model has been developed for describing the dynamic operation of the N-formylmorpholine extractive distillation column and the corresponding solvent recovery column in the benzene extraction plant. The NRTL equation was used to calculate the equilibrium and thermodynamic properties of the mixtures. The validity of the model in terms of temperature, pressure and split fraction was examined using actual plant data at steady-state conditions. Comparison betwee (more) n model results and plant data shows good consistency. In order to improve the control of the process and selection of the optimal control strategy, the model was used to find the optimum values of the constants of the controllers with Nelder-Mead algorithm during unsteady-state operation by minimizing the deviation from steady-state conditions. The outcome of this study could be used by operators and engineers to increase the productivity of the unit.

2008-12-01

Surface physics with cold and thermal neutron reflectometry. Progress report, April 1, 1991--September 30, 1993

Optimizing the acquisition time profile for a planar integral measurement system with a spinning slat collimator

Within the past two and one half years of the project ``Surface Physics With Cold and Thermal Neutron Reflectometry`` a new thermal neutron reflectometer was constructed at the Rhode Island Nuclear Science Center (RINSC). It was used to study various liquid and solid surfaces. Furthermore, neutron reflection experiments were be un at different laboratories in collaboration with Dr. G.P. Fetcher (at Argonne National Laboratory), Dr. T. Russell (IBM Almaden) and Drs. S.K. Satija and A. Karim (at the National Institute for Standards and Technology). The available resources allowed partial construction of an imaging system for ultracold neutrons. It is expected to provide an extremely high resolution in momentum and energy transfer in surface studies using neutron reflectometry. Much of the work reported here was motivated by the possibility of later implementation at the planned Advanced Neutron Source at Oak Ridge. In a separate project the first concrete plans for ...

1993-09-01

Accretion onto Supermassive Black Holes in Quasars: Learning from Optical/UV Observations

This article considers a hypothetical imaging device with a spinning slat collimator that measures parallel-planar-integral data from an object. This device rotates around the object 180 deg. and stops at N positions uniformly distributed over this 180 deg. . At each stop, the device spins on its own axis 180 deg. and acquires measurements at M positions uniformly distributed over this 180 deg. . For a fixed total imaging time, an optimal distribution of the scanning time among the data measurement locations is searched by a nonlinear programming method: Nelder-Mead's simplex method. The optimal dwell time is approximately proportional to the weighting factor in the backprojector of the reconstruction algorithm. By using an optimal dwell-time profile, the reconstruction signal-to-noise ratio has a gain of 23%-24% for the filtered backprojection algorithm and a gain of 10%-18% for the iterative algorithms, compared with the situation when a constant dwell-time ...

2005-09-01

CERN Document Server

Accretion processes in quasars and active galactic nuclei are still poorly understood, especially as far as the connection between observed spectral properties and physical parameters is concerned. Quasars show an additional degree of complexity compared to stars that is related to anisotropic emission/obscuration influencing the observed properties in most spectral ranges. This complicating factor has hampered efforts to define the equivalent of an Hertzsprung-Russel diagram for quasars. Even if it has recently become possible to estimate black hole mass and Eddington ratio for sources using optical and UV broad emission lines, the results are still plagued by large uncertainties. Nevertheless, robust trends are emerging from multivariate analysis of large spectral datasets of quasars. A firm observational basis is being laid out by accurate measurements of broad emission line properties especially when the source rest-frame is known. We consider the most widely ...

2006-01-01

Radiation testing of organic ion exchange resins

Radiation testing of organic ion exchange resins

A number of ion exchange materials are being evaluated as part of the Tank Waste Remediation System (TWRS) Pacific Northwest Laboratory (PNL) Pretreatment Project for the removal of "1"3"7Cs from aqueous tank wastes. Two of these materials are organic resins; a phenol-formaldehyde resin (Duolite CS-100) produced by Rohm and Haas Co. (Philadelphia, Pennsylvania) and a resorcinol-formaldehyde (RF) resin produced by Boulder Scientific Co. (Mead, Colorado). One of the key parameters in the assessment of the organic based ion exchange materials is its useful lifetime in the radioactive and chemical environment that will be encountered during waste processing. The focus of the work presented in this report is the radiation stability of the CS-100 and the RF resins. The scope of the testing included one test with a sample of the CS-100 resin and testing of two batches of the RF resin (BSC-187 and BSC-210). Samples of the exchangers were irradiated with a "6"0Co source to ...

1983-04-11

MONTE CARLO SIMULATIONS OF GLOBULAR CLUSTER EVOLUTION. V. BINARY STELLAR EVOLUTION

A number of ion exchange materials are being evaluated as part of the Tank Waste Remediation System (TWRS) Pacific Northwest Laboratory (PNL) Pretreatment Project for the removal of {sup 137}Cs from aqueous tank wastes. Two of these materials are organic resins; a phenol-formaldehyde resin (Duolite CS-100) produced by Rohm and Haas Co. (Philadelphia, Pennsylvania) and a resorcinol-formaldehyde (RF) resin produced by Boulder Scientific Co. (Mead, Colorado). One of the key parameters in the assessment of the organic based ion exchange materials is its useful lifetime in the radioactive and chemical environment that will be encountered during waste processing. The focus of the work presented in this report is the radiation stability of the CS-100 and the RF resins. The scope of the testing included one test with a sample of the CS-100 resin and testing of two batches of the RF resin (BSC-187 and BSC-210). Samples of the exchangers were irradiated with a {sup 60}Co ...

1995-09-01

Gaussian pulse decomposition: an intuitive model of electrocardiogram waveforms.

We study the dynamical evolution of globular clusters containing primordial binaries, including full single and binary stellar evolution using our Monte Carlo cluster evolution code updated with an adaptation of the single and binary stellar evolution codes SSE and BSE from Hurley et al. We describe the modifications that we have made to the code. We present several test calculations and comparisons with existing studies to illustrate the validity of the code. We show that our code finds very good agreement with direct N-body simulations including primordial binaries and stellar evolution. We find significant differences in the evolution of the global properties of the simulated clusters using stellar evolution compared with simulations without any stellar evolution. In particular, we find that the mass loss from the stellar evolution acts as a significant energy production channel simply by reducing the total gravitational binding energy and can significantly prolong the initial core ...

2010-08-10

This study presents a novel approach to modeling the electrocardiogram (ECG): the Gaussian pulse decomposition. Constituent waves of the ECG are decomposed into and represented by Gaussian pulses using an iterative algorithm: the chip away decomposition (ChAD) algorithm. At each iteration, a nonlinear minimization method is used to fit a portion of the ECG waveform with a single Gaussian pulse, which is then subtracted from the ECG waveform. The process iterates on the resulting residual waveform until the normalized mean square error is below an acceptable level. Three different minimization methods were compared for their applicability to the ChAD algorithm; the Nelder-Mead simplex method was found to be more noise-tolerant than the Newton-Raphson method or the steepest descent method. Using morphologically different ECG waveforms from the MIT-BIH arrhythmia database, it was demonstrated that the ChAD algorithm is capable of modeling not only normal beats, but ...

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Attempting immortality