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Interannual/decadal variability in MJO activity as diagnosed in the 40-year NCEP/NCAR reanalysis and simulated in an ensemble of GISST integrations

Description: The Madden-Julian Oscillation (MJO) is the dominant mode of tropical variability at intraseasonal timescales. It displays substantial interannual variability in intensity which may have important implications for the predictability of the coupled system. The reasons for this interannual variability are not understood. The interannual behaviour of the MJO has been diagnosed initially in the 40-year NCEP/NCAR Reanalysis by calculating the variance of the 20-100 day filtered zonal mean zonal wind (10 o N-10 o S averaged) in a 100- day moving window. The results suggest that prior to the mid-1970s the activity of the MJO was consistently lower than during the latter part of the record. This may be related to either inadequacies in the data coverage, particularly over the tropical Indian Ocean prior to the introduction of satellite observations, or to the real effects of a decadal timescale warming in the tropical SSTs. This interdecadal trend is captured by the dominant EOF (explaining 28% of the variance) of the monthly mean SSTs (after removal of the mean seasonal cycle), as used in the NCEP/NCAR Reanalysis for the region of the tropics where the MJO is convectively active (i.e., 60 o E-180 o E, 20 o S-20 o N). During the latter part of 1970�s there was an abrupt change from a predominantly negative PC1 (i.e. colder Indian Ocean) to a positive PC1 (i.e. warmer Indian Ocean), indicative of a general warming of the tropical Indian Ocean by at least 0.5 o K over the last 40 years. However, on interannual timescales, the teleconnection patterns between MJO activity and SST show only a weak, barely significant, influence of El Niño in which the MJO is more active during the cold phase. As well as the NCEP/NCAR Reanalysis, a 4-member ensemble of 45 year integrations with the Hadley Centre climate model ...
Date: April 21, 1999
Creator: Nortley, F; Rowell, D P; Slingo, J M & Sperber, K R
Partner: UNT Libraries Government Documents Department

A Study of Weld Porosity in Containers for the Storage of Plutonium Containing Materials

Description: An autogenous GTAW closure weld was developed for the Department of Energy's (DOE) primary container for the storage of plutonium-bearing materials. The occurrence of porosity at the tie-in point of the closure weld was investigated. The primary cause of the porosity was linked to the geometry at the root of the closure weld joint. This paper describes the mechanistic model that was developed to describe and predict the porosity.
Date: April 21, 2003
Creator: Daugherty, W.L.
Partner: UNT Libraries Government Documents Department

Gas Generation Measurements of Scrap Pu/U Materials Using a Bell Jar

Description: A bell jar is used to determine containment vessel pressurization due to gas generation from plutonium/uranium materials. Seventy eight food pack cans containing plutonium and uranium oxide bearing materials have been tested to date. Minimal change in pressure (increase or decrease) occurred in fifty one cases, depressurization occurred in seventeen cases, and pressurization occurred in ten cases. Pressurization is considered to be linked to the presence of certain impurities such as magnesium oxide.
Date: April 21, 2003
Creator: Kies, J.
Partner: UNT Libraries Government Documents Department

Large distributed control system using ADA in fusion research

Description: Construction of the National Ignition Facility laser at Lawrence Livermore National Laboratory features a large distributed control system constructed using object-oriented software engineering techniques. Control of 60,000 devices is effected using a network of some 500 computers that run software written in Ada and communicating through CORBA. The project has completed its final design review; implementation of the first of five planned increments will be delivered at the end of fiscal year 1998. Preliminary measures of the distributed controls performance confirm the design decisions reported in this paper, and the measurement and supporting simulation of full system performance continue.
Date: April 21, 1998
Creator: Woodruff, J. P., LLNL
Partner: UNT Libraries Government Documents Department

Electromagnetic interactions GEneRalized (EIGER): algorithm abstraction and HPC implementation

Description: Modern software development methods combined with key generalizations of standard computational algorithms enable the development of a new class of electromagnetic modeling tools. This paper describes current and anticipated capabilities of a frequency domain modeling code, EIGER, which has an extremely wide range of applicability. In addition, software implementation methods and high performance computing issues are discussed.
Date: April 21, 1998
Creator: Sharpe, R.M., LLNL
Partner: UNT Libraries Government Documents Department

A Criticality Safety Study on Storing Unirradiated Cintichem-Type Targets at Sandia National Laboratories

Description: This criticality safety analysis is performed to determine the effective multiplication factor (k{sub eff}) for a storage cabinet filled with unirradiated Cintichem-type targets. These targets will be used to produce {sup 99}Mo at Sandia National Laboratories and will be stored on-site prior to irradiation in the Annular Core Research Reactor. The analysis consisted of using the Monte Carlo code MCNP (Version 4A) to model and predict the k{sub eff} for the proposed dry storage configuration under credible loss of geometry and moderator control. Effects of target pitch, non-uniform loading, and target internal/external flooding are evaluated. Further studies were done with deterministic methods to verify the results obtained from MCNP and to obtain a clearer understanding of the parameters affecting system criticality. The diffusion accelerated neutral particle transport code ONEDANT was used to model the target in a one-dimensional, infinite half-slab geometry and determine the critical slab thickness. Hand calculations were also completed to determine the critical slab thickness with modified one-group, and one-group, two region approximations. Results obtained from ONEDANT and the hand calculations were compared to applicable cases in a commonly used criticality safety analysis handbook. Overall, the critical slab thicknesses obtained in the deterministic analysis were much larger than the dimensions of the cabinet and further support the predictions by MCNP that a critical system cannot be attained for the base case or in conditions where loss of geometry and moderation control occur.
Date: April 21, 1999
Creator: Romero, D.J.; Parma, E.J. & Busch, R.D.
Partner: UNT Libraries Government Documents Department

Effect of Substrate Composition on the Piezoelectric Response of Reactively Sputtered AlN Thin Films

Description: Deposition parameters were found to have a marked effect on piezoelectric response of reactive radio frequency (RF) sputtered AlN thin films. The authors observed peizoelectric response values ranging from {minus}3.5 to +4.2 pm/V for 1 {micro}m thick AlN films deposited onto Ti/Ru electrode stacks. An investigation of the effects of deposition parameters, in particular the nature of the Ru/AlN interface, was conducted. The lag time between deposition of adjacent thin film layers appeared to have the greatest affect on the value of the piezoelectric response. This suggests that chemical reaction occurring on the Ru thin film surface is responsible for changing an important thin film property such as dipole orientation within the overlying AlN thin film.
Date: April 21, 1999
Creator: Clem, P.G.; Dimos, D.B.; Gonzales, D.M.; Ruffner, J.A. & Tuttle, B.A.
Partner: UNT Libraries Government Documents Department

Hybrid Blends of Non-Traditional Safety and Reliability Analysis Tools

Description: Traditional safety and reliability analysis methods are applicable to many standard problems, including those examples illustrated in most formal courses. However, there are many real-world situations for which non-traditional methods appear to be more appropriate, mainly because most practical problems involve substantial subjectivity about the inputs and models used. This paper surveys some of the most applicable approaches found in a recent research study. Each approach is developed individually and is illuminated by selecting example situations of apparent applicability. Then, the combinational blending of the approaches with each other and with traditional methodology is discussed.
Date: April 21, 1999
Creator: Cooper, J.A.
Partner: UNT Libraries Government Documents Department

Work of Adhesion Measurements of Silicone Networks Using Contract Mechanics

Description: Work of adhesion (Wa) measurements are being studied for several types of polymer/metal combinations in order to obtain a better understanding of the adhesive failure mechanisms for systems containing encapsulated and bonded components. A primary concern is whether studies of model systems can be extended to systems of technological interest. One study performed in our laboratory involved the determination of Wa between silicone (PDMS) and Al surfaces in order to establish potential adhesive failure mechanisms. Our initial work with PDMS was based on Dow Corning 170 Sylgard. PDMS hemispheres were synthesized following the procedure outlined by Chaudhury and Whitesides where the filler was stripped from the commercial silicone by centrifuging. Wa between PDMS surfaces was determined using the JKR method. Our results for the Wa of PDMS were in agreement with those reported by Chaudhury and Whitesides. However, further JKR studies using these PDMS hemispheres on flat Al surfaces were fraught with difficulty. We could not discriminate hydrogen-bonding effects between Al{sub 2}O{sub 3} and hydroxyl groups in the PDMS and other possible bonding mechanisms. It was suggested that commercial systems contain inhibitors and additives that interfere with understanding the PMDS/Al interface. Therefore, the current study uses pure PDMS networks synthesized in our lab. Also, two contact mechanics methods were deployed to measure the Wa--JKR method using two hemispheres and a LEFM method using a cylinder containing a circumferential crack. This paper contains a description of the synthesis of the PDMS used for these studies and the determination of Wa between PDMS surfaces using the JKR method, contact angle measurements, and a LEFM method that consists of a cylinder containing a circumferential crack.
Date: April 21, 1999
Creator: Benkoski, J.; Emerson, J.A.; Miller, G.V. & Pearson, R.A.
Partner: UNT Libraries Government Documents Department

Server-Side JavaScript Debugging: Viewing the Contents of an Object

Description: JavaScript allows the definition and use of large, complex objects. Unlike some other object-oriented languages, it also allows run-time modifications not only of the values of object components, but also of the very structure of the object itself. This feature is powerful and sometimes very convenient, but it can be difficult to keep track of the object's structure and values throughout program execution. What's needed is a simple way to view the current state of an object at any point during execution. There is a debug function that is included in the Netscape server-side JavaScript environment. The function outputs the value(s) of the expression given as the argument to the function in the JavaScript Application Manager's debug window [SSJS].
Date: April 21, 1999
Creator: Hampton, J. & Simons, R.
Partner: UNT Libraries Government Documents Department

Azo Dyes and Their Interfacial Activity: Implications for Multiphase Flow Experiments

Description: Interfacial effects play an important role in governing multiphase fluid behavior in porous media (Neustadter 1984; Tuck et al. 1988). For instance, several dimensionless numbers have been developed to express important force ratios applicable to multiphase flow in porous media (Morrow and Songkran 1981; Chatzis and Morrow 1984; Wardlaw 1988; Pennell et al. 1996; Dawson and Roberts 1997). These force ratios emphasize the importance of interfacial properties. Our objectives are to provide chemical information regarding the dyes commonly used in multiphase flow visualization studies and to show the surface chemistry effects of the most commonly used dye, Sudan IV, in the tetrachloroethylene (PCE)-water-glass system
Date: April 21, 1999
Creator: Tuck, D.M.
Partner: UNT Libraries Government Documents Department

Evaluation of Arizona's enhanced I/M program

Description: MOBILE5 slightly overpredicts initial reductions in CO and HC, and dramatically overpredicts initial reductions in NOx. About one-third of the vehicles that fail initial I/M testing do not complete the I/M program. Only a small portion of these receive a waiver. Initial I/M repair effectiveness as measured by remote sensing is only half of that as measured by IM240. Possible causes are sensitivity to operating mode, and how long after repair emissions are measured. 37% of the vehicles that initially fail and eventually pass in 1995 fail again in 1997. Half of these fail for the same combination of pollutants in both years. Vehicles that never pass the Im240 are still being driven in the I/M area; these vehicles are from all model years.
Date: April 21, 1999
Creator: Wenzel, Tom
Partner: UNT Libraries Government Documents Department

Plasma Decontamination of Uranium From the Interior of Aluminum Objects

Description: RF plasma glow discharges are being investigated for removing and recovering radioactive elements from contaminated objects, especially those contaminated with transuranic (TRU) materials. These plasmas, using nitrogen trifluoride as the working gas, have been successful at removing uranium and plutonium contaminants from test coupons of stainless steel and aluminum surfaces, including small cracks and crevices, and the interior surfaces of relatively hard to reach aluminum pipes. Contaminant removal exceeded 99.9% from simple surfaces and contaminant recovery using cryogenic traps has exceeded 50%. Work continues with the objective of demonstrating that transuranic contaminated waste can be transformed to low level waste (LLW) and to better understand the physics of the interaction between plasma and surface contaminants. This work summarizes the preliminary results from plasma decontamination from the interior of aluminum objects--the nooks and crannies experiments.
Date: April 21, 1997
Creator: Veilleux, J.M.; Munson, C.; Fitzpatrick, J.; Chamberlin, E.P. & El-Genk, M.S.
Partner: UNT Libraries Government Documents Department

A quality of service architecture that combines resource reservation and application adaptation

Description: Reservation and adaptation are two well-known and effective techniques for enhancing the end-to-end performance of network applications. However, both techniques also have limitations, particularly when dealing with high-bandwidth, dynamic flows: fixed-capability reservations tend to be wasteful of resources and hinder graceful degradation in the face of congestion, while adaptive techniques fail when congestion becomes excessive. We propose an approach to quality of service (QoS) that overcomes these difficulties by combining features of reservations and adaptation. In this approach, a combination of online control interfaces for resource management, a sensor permitting online monitoring, and decision procedures embedded in resources enable a rich variety of dynamic feedback interactions between applications and resources. We describe a QoS architecture, GARA, that has been extended to support these mechanisms, and use three examples of application-level adaptive strategies to show how this framework can permit applications to adapt both their resource requests and behavior in response to online sensor information.
Date: April 21, 2000
Creator: Foster, I.; Roy, A. & Sander, V.
Partner: UNT Libraries Government Documents Department

Maleimide Functionalized Siloxane Resins

Description: In-situ filling through hydrolysis and condensation of silicon alkoxides has been utilized to generate nanocomposites in which the filler phase can be intimately associated with the polymer on relatively small length scales. One problem of the method has been achieving useful fill volumes without bulk phase separation of the reacting silicon monomer from the polymer. In this paper, we describe the preparation of a new class of nanocomposite materials in which the inorganic filler phase is pre-assembled before copolymerization with an organic species. Maleimide monomers, prepared from alkoxysilylpropyl amines and maleic anhydride, were protected against side reactions by forming the oxonorbornene Diels-Alder adduct with furan. The monomers were then reacted under sol-gel conditions to form oligomers or polymers-the filler phase. The material was activated by thermal deprotection of the maleimide and reacted with organic monomers or polymers to form the filled nanocomposite.
Date: April 21, 1999
Creator: Shaltout, R.M.; Loy, D.A. & Wheeler, D.R.
Partner: UNT Libraries Government Documents Department

Chemical vapor deposition coating for micromachines

Description: Two major problems associated with Si-based MEMS devices are stiction and wear. Surface modifications are needed to reduce both adhesion and friction in micromechanical structures to solve these problems. In this paper, the authors will present a process used to selectively coat MEMS devices with tungsten using a CVD (Chemical Vapor Deposition) process. The selective W deposition process results in a very conformal coating and can potentially solve both stiction and wear problems confronting MEMS processing. The selective deposition of tungsten is accomplished through silicon reduction of WF{sub 6}, which results in a self-limiting reaction. The selective deposition of W only on polysilicon surfaces prevents electrical shorts. Further, the self-limiting nature of this selective W deposition process ensures the consistency necessary for process control. Selective tungsten is deposited after the removal of the sacrificial oxides to minimize process integration problems. This tungsten coating adheres well and is hard and conducting, requirements for device performance. Furthermore, since the deposited tungsten infiltrates under adhered silicon parts and the volume of W deposited is less than the amount of Si consumed, it appears to be possible to release stuck parts that are contacted over small areas such as dimples. Results from tungsten deposition on MEMS structures with dimples will be presented. The effect of wet and vapor phase cleanings prior to the deposition will be discussed along with other process details. The W coating improved wear by orders of magnitude compared to uncoated parts. Tungsten CVD is used in the integrated-circuit industry, which makes this approach manufacturable.
Date: April 21, 2000
Creator: Mani, Seethambal S.; Fleming, James G.; Sniegowski, Jeffry J.; DE BOER,MAARTEN P.; Irwin, Lawrence W.; Walraven, Jeremy A. et al.
Partner: UNT Libraries Government Documents Department

Issues Associated with the Conveyance and Transfer of DOE Lands under Public Law 105-119

Description: Public Law 105-119 (Law) was enacted in November 1997 as part of the Defense Authorization Act of 1998 (Act). The Law specifically requires the US Department of Energy (DOE) to identify lands that are suitable for conveyance or transfer at Los Alamos National Laboratory (LANL) within 90 days after enactment of the Act. In general, suitable lands include those parcels that are not required to meet the national security missions assigned to DOE at LANL within a ten year period beginning on the date of enactment of the Act. Additional suitability criteria are addressed below and include the need to establish clear title to the land and to restore areas contaminated with hazardous wastes. This proposed change in future land ownership is intended to serve as the final settlement of DOE community assistance obligations with respect to LANL and Los Alamos County and to stimulate economic development.
Date: April 21, 1999
Creator: Ladino, A.G.
Partner: UNT Libraries Government Documents Department

A practical microgripper by fine alignment, eutectic bonding and SMA actuation

Description: A silicon microgripper with a large gripping force, a relatively rigid structural body, and flexibility in functional design is presented. The actuation is generated by Ni-Ti-Cu shape memory alloy (SMA) films and the stress induced can deflect each side of the microgripper up to 55 {mu}m for a total gripping motion of 110 {mu}m. When fully open, the force exerted by the film corresponds to a 40 mN gripping force on the tip of the gripper.
Date: April 21, 1995
Creator: Lee, A. P.; Ciarlo, D. R. & Krulevitch, P. A.
Partner: UNT Libraries Government Documents Department

The direct limit on the Higgs Mass and the SM Fit

Description: Because of two 3{sigma} anomalies, the Standard Model (SM) fit of the precision electroweak data has a poor confidence level, CL = 0.02. Since both anomalies involve challenging systematic issues, it might appear that the SM could still be valid if the anomalies resulted from underestimated systematic error. Indeed the CL of the global fit could then increase to 0.71, but that fit predicts a small Higgs boson mass, m{sub H} = 45 GeV, that is inconsistent at 95% CL with the lower limit, m{sub H} > 114 GeV, established by direct searches. The data then favor new physics whether the anomalous measurements are excluded from the fit or not, and the Higgs boson mass cannot be predicted until the new physics is understood. Some measure of statistical fluctuation would be needed to maintain the validity of the SM. New physics is favored, but the SM is not definitively excluded.
Date: April 21, 2003
Creator: Chanowitz, Michael S.
Partner: UNT Libraries Government Documents Department

The mean evolution and variability of the Asian summer monsoon: comparison of ECMWF and NCEP/NCAR reanalyses

Description: The behavior of the Asian Summer Monsoon is compared using the European Centre for Medium Range Weather Forecasts Reanalysis (ERA) and the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis (Kalnay et al. 1996). The goals of this paper are to identify common features between the reanalyses, to assess their robustness for model validation, and especially to use reanalyses to develop their understanding of the mean evolution of the Asian Summer Monsoon and the characteristics of its interannual and intraseasonal variability (Annamalai et al. 1999).
Date: April 21, 1999
Creator: Annamalai, H.; Hodges, K.; Slingo, J.M. & Sperber, K.R.
Partner: UNT Libraries Government Documents Department

VACUUM WINDOW DESIGN FOR HIGH-POWER LASERS.

Description: One of the problems in the high-power lasers design is in outcoupling of a powerful laser beam out of a vacuum volume into atmosphere. Usually the laser device is located inside a vacuum tank. The laser radiation is transported to the outside world through the transparent vacuum window. While considered transparent, some of the light passing through the glass is absorbed and converted to heat. For most applications, these properties are academic curiosities; however, in multi-kilowatt lasers, the heat becomes significant and can lead to a failure. The absorbed power can result in thermal stress, reduction of light transmission and, consequently, window damage. Modern optical technology has developed different types of glass (Silica, BK7, diamond, etc.) that have high thermal conductivity and damage threshold. However, for kilo- and megawatt lasers the issue still remains open. In this paper we present a solution that may relieve the heat load on the output window. We discuss advantages and issues of this particular window design.
Date: April 21, 2005
Creator: SHAFTAN, T.
Partner: UNT Libraries Government Documents Department

The relationship between intraseasonal and interannual variability during the asian summer monsoon

Description: The purpose of this paper is to investigate intraseasonal (30-70 days) and higher frequency (5-30 days) variability and its relationship to interannual variability. Various modelling studies have suggested a link between intraseasonal and interannual variability of the Asian summer monsoon. This relationship has been mainly based upon the similar spatial structures of the dominant EOF patterns of the monsoon circulation on intraseasonal and interannual time scales from simulations with simple models and atmospheric general circulation models. Here we investigate these relationships using 40 years of NCEP/NCAR Reanalysis. Motivation for this study is embodied in the suggestions of Charney and Shukla (1981) that boundary forcing (e.g., sea surface temperature) may predispose the monsoon system towards a dry or wet state, and the result of Palmer (1994), using the Lorenz (1963) model, that the probability of being in one regime of phase space or another is no longer equally probable in the presence of external forcing. To investigate the influence of the boundary forcing, the probability distribution functions (PDF�s) of the principal components are given.
Date: April 21, 1999
Creator: Annamalai, H; Slingo, J M & Sperber, K R
Partner: UNT Libraries Government Documents Department