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Critical dimension sensitivity to post-exposure bake temperaturevariation in EUV photoresists

Description: Chemically amplified resists depend upon the post-exposure bake (PEB) process to drive the deprotection reactions (in positive resists) that lead to proper resist development. For this reason they often exhibit critical dimension (CD) sensitivity to PEB temperature variation. In this work the effects of variation in different aspects of the PEB step on post-develop CD are studied for two extreme ultraviolet (EUV) photoresists. The spatial and temporal temperature uniformity of the PEB plate is measured using a wireless sensor wafer. Programmed variations in the bake plate temperature set point are then used to measure the CD sensitivity to steady state temperature variation. In addition, the initial temperature ramp time is modified using a thin sheet of polyimide film between the wafer and the bake plate. This allows for measurement of the CD sensitivity to transient temperature variation. Finally, the bake time is adjusted to measure the CD sensitivity to this parameter.
Date: January 11, 2005
Creator: Cain, Jason P.; Naulleau, Patrick & Spanos, Costas J.
Partner: UNT Libraries Government Documents Department

Numerical studies of enthalpy and CO2 transients in two-phasewells

Description: Numerical studies of enthalpy and CO2 transients for wellscompleted in composite reservoir systems are carried out. Both constantrate and constant pressure production are considered. The results showthat relatively small variations in hydrologic parameters and vaporsaturation can have large effects on the enthalpy and CO2 content of theproduced fluids. Field data are presented that illustrate the theoreticalresults obtained.
Date: April 1, 1984
Creator: Bodvarsson, Gudmundur S.
Partner: UNT Libraries Government Documents Department

Measured strain in Nb3Sn coils during excitation and quence

Description: The strain in a high field Nb{sub 3}Sn coil was measured during magnet assembly, cool-down, excitation and spot heater quenches. Strain was measured with a full bridge strain gauge mounted directly over the turns and impregnated with the coil. Two such coils were placed in a 'common coil' fashion capable of reaching 11 T at 4.2 K. The measured steady state strain in the coil is compared with results obtained using the FEM code ANSYS. During quenches, the transient strain (due to temperature rise) was also measured and compared with the calculated mechanical time response to a quench.
Date: June 1, 2005
Creator: Caspi, S.; Barlett, S.E.; Dietderich, D. R.; Ferracin, P.; Gourlay, S. A.; Hannaford, C. R. et al.
Partner: UNT Libraries Government Documents Department


Description: Included in the conference proceedings are 69 papers grouped into the categories on the experimental and theoretical aspects of the scattering law,'' of spectra ln lattices and infinite media, and of transient and asymptotic phenomena. One paper in each of the categories is a summary of the material presented by the other papers in that group. Separate abstracts have been prepared for 52 papers, and 15 papers have been previously abstracted in NSA. (M.P.G.)
Date: October 31, 1963
Partner: UNT Libraries Government Documents Department

A study of temperature transients at the inlet of a turbojet engine

Description: Report presenting wind-tunnel experiments on the effect of rapid temperature increases at the inlet of an engine in order to learn why inlet temperature transients disturb the operation of turbojet engines. The study was made over a range of altitudes, temperature-rise rates, and engine speeds. Results regarding pressure-ratio histories, required temperature rise for stall, effect of partial admission of hot gases to the compressor inlet, effect of altitude on stall and blowout, and effect of remedial measures are provided.
Date: June 26, 1957
Creator: Wallner, Lewis E.; Useller, James W. & Saari, Martin J.
Partner: UNT Libraries Government Documents Department


Description: We determine the impedance of a cylindrical metal tube (resistor) of radius a, length g, and conductivity {sigma}, attached at each end to perfect conductors of semi-infinite length. Our main interest is in the asymptotic behavior of the impedance at high frequency, k >> 1/a. In the equilibrium regime, , the impedance per unit length is accurately described by the well-known result for an infinite length tube with conductivity {sigma}. In the transient regime, ka{sup 2} >> g, we derive analytic expressions for the impedance and wakefield.
Date: May 15, 2005
Partner: UNT Libraries Government Documents Department

A Multisensor system for the detection and characterization of UXOMM-0437

Description: A prototype active electromagnetic system has been developedfor detecting and characterizing UXO. The system employs two orthogonalvertical loop transmitters and a pair of horizontal loop transmittersspaced apart vertically by 0.7 m. Eight vertical field detectors aredeployed in the plane of each of the horizontal loops and are arranged tomeasure offset vertical gradients of the fields. The location andorientation of the three principal polarizabilities of a target can berecovered from a single position of the transmitter-receiver system.Further characterization of the target is obtained from the broadbandresponse. The system employs a bipolar half sine pulse train currentwaveform and the detectors are dB/dt induction coils designed to minimizethe transient response of the primary field pulse. The target transientis recovered in a 40 mu-sec to 1.0 msec window. The ground responseimposes an early time limit on the time window and system/ambient noiselimits the late time response. Nevertheless for practical transmittermoments and optimum receivers the size and the ratio of conductivity topermeability canbe accurately recovered. The prototype system hassuccessfully recovered the depths and polarizabilities of ellipsoidaltest targets.
Date: June 1, 2006
Creator: Gasperikova, Erika; Becker, A.; Morrison, H.F. & Smith, J.T.
Partner: UNT Libraries Government Documents Department


Description: Water hammer during multi-phase flow is rather complex, but in some cases an upper limit to the pressure surge magnitude during water hammer can be estimated. In the case considered here, a two mile long pipeline with a single high point was permitted to partially drain. Due to gravitational effects, air bubbles up through the pipe line to its highest point, but the time required for air to reach the top of the pipe is rather long. Consequently, some transients caused by valve operations are affected by air entrapment and some are not. The intent of this research was to investigate the complex interactions between air, water vapor, and liquid during water hammer in a long pipe with one end of the pipe open to atmospheric conditions. To understand the system dynamics, experimental data was obtained from a long pipeline with an open end and also from a short, transparent tube. Transient calculations were performed for valve closures and pump operations as applicable. The limitations of available calculation techniques were considered in detail.
Date: June 9, 2008
Creator: Leishear, R
Partner: UNT Libraries Government Documents Department

Hydrogen adsorption on Ru(001) studied by Scanning TunnelingMicroscopy

Description: The adsorption of hydrogen on Ru(001) was studied by scanning tunneling microscopy at temperatures around 50 K. Hydrogen was found to adsorb dissociatively forming different ordered structures as a function of coverage. In order of increasing coverage {theta} in monolayers (ML) these were ({radical}3 x {radical}3)r30{sup o} at {theta} = 0.3 ML; (2 x 1) at {theta} = 0.50 ML, (2 x 2)-3H at {theta} = 0.75, and (1 x 1) at {theta} = 1.00. Some of these structures were observed to coexist at intermediate coverage values. Close to saturation of 1 ML, H-vacancies (unoccupied three fold fcc hollow Ru sites) were observed either as single entities or forming transient aggregations. These vacancies diffuse and aggregate to form active sites for the dissociative adsorption of hydrogen.
Date: January 18, 2008
Creator: Tatarkhanov, Mous; Rose, Franck; Fomin, Evgeny; Ogletree, D.Frank & Salmeron, Miquel
Partner: UNT Libraries Government Documents Department

Ultrafast Enhancement of Ferromagnetism via Photoexcited Holes inGaMnAs

Description: We report on the observation of ultrafast photo-enhanced ferromagnetism in GaMnAs. It is manifested as a transient magnetization increase on a 100-ps time scale, after an initial sub-ps demagnetization. The dynamic magnetization enhancement exhibits a maximum below the Curie temperature {Tc} and dominates the demagnetization component when approaching {Tc}. We attribute the observed ultrafast collective ordering to the p-d exchange interaction between photoexcited holes and Mn spins, leading to a correlation-induced peak around 20K and a transient increase in {Tc}.
Date: February 17, 2007
Creator: Wang, J.; Cotoros, I.; Dani, K.M.; Liu, X.; Furdyna, J.K. & Chemla, D.S.
Partner: UNT Libraries Government Documents Department

Thermal, Electrical and Mechanical Response to a Quench in Nb3Sn Superconducting Coils

Description: During a quench, significant temperatures can arise as a magnet's stored energy is dissipated in the normal zone. Temperature gradients during this process give rise to localized strains within the coil. Reactive forces in the magnet structure balance the electromagnetic and thermal forces and maintain on equilibrium. In this paper we present a complete 3D finite element analysis of a racetrack coil. Specifically, the analysis focuses on thermal, electrical and mechanical conditions in a 10T Nb{sub 3}Sn coil built and tested as part of LBNL's Subscale Magnet Program. The study attempts to simulate time history of the temperature and voltage rise during quench propagation. The transient thermal stress after the quench is then evaluated and discussed.
Date: October 1, 2003
Creator: Ferracin, P.; Caspi, S.; Chiesa, L.; Gourlay, S.A.; Hafalia, R.r.; Imbasciati, L. et al.
Partner: UNT Libraries Government Documents Department

A Preliminary Low-Frequency Electromagnetic Analysis of a Flux Concentrator

Description: The objective of this investigation was to conduct a quick, preliminary transient magnetostatic analysis of a Brechna-type[1] flux concentrator to determine its feasibility for collecting positrons in the International Linear Collider. The magnetostatic transient module of Maxwell 3D, Version 10, from the Ansoft Corporation was used to model the flux concentrator.
Date: June 7, 2006
Creator: Mayhall, D J
Partner: UNT Libraries Government Documents Department

Breakthrough Time for the Source-Sink Well Doublet

Description: A pressure transient analysis method is presented for interpreting breakthrough time between two constant rate wells. The wells are modeled as two line source wells in an infinite reservoir. The first well injects at a constant rate and the second well produces at a constant rate. We studied the effects of transient pressure conditions on breakthrough time. The first arrival of injected fluid at the production well may be significantly longer under transient condition than under steady state condition. A correlation of the deviation of the breakthrough time for transient pressure conditions from the steady state condition is presented.
Date: January 21, 1986
Creator: Menninger, Will & Sageev, Abraham
Partner: UNT Libraries Government Documents Department

Femtosecond isomerization dynamics in the ethylene cation measured in an EUV-pump NIR-probe configuration

Description: Dynamics in the excited ethylene cation C{sub 2}H{sub 4}{sup +} lead to isomerization to the ethylidene configuration (HC-CH{sub 3}){sup +}, which is predicted to be a transient configuration for electronic relaxation. With an intense femtosecond EUV (extreme ultraviolet) pump pulse to populate the excited state, and an NIR (near infrared) probe pulse to produce the fragments CH{sup +} and CH{sub 3}{sup +} (which provides a direct signature of ethylidene), we measure optimum fragment yields at a probe delay of 80 fs. Also, an H{sub 2}-stretch transient configuration, yielding H{sub 2}{sup +} upon probing, is found to succeed the ethylidene configuration. We find that a simple single- or double-decay model does not match the data, and we present a modified model (introduction of an isomerization delay of 50 {+-} 25 fs) that does provide agreement.
Date: March 17, 2009
Creator: van Tilborg, Jeroen; Allison, Tom; Wright, Travis; Hertlein, Marc; Falcone, Roger; Liu, Yanwei et al.
Partner: UNT Libraries Government Documents Department

From shock response spectrum to temporal moments and vice-versa

Description: Temporal momerils have been used in engineering mechanics to condense the information contained in the shock response spectrum into a few scalar quantities. This paper presents an application of temporal moments to the propagation of an explosive-driven shock wave through an assembly of metallic parts. For this particular application, it is shown that temporal moments characterize the response of the system better than other features traditionally used in the analysis of nonlinear, transient events, such as the peak response or 10% duration of event. The inverse problem is also illustrated: the original, time-domain signals and their shock response spectra can be reconstructed from the temporal moments. This property makes temporal moments features of choice for the analysis of experimental data or the development of numerical models because they are low-dimensional quantities; they capture transient dynamics well; and they can be used to re-generate the original time signals.
Date: January 1, 2002
Creator: Hemez, F. M. (Fran├žois M.) & Doebling, S. W. (Scott W.)
Partner: UNT Libraries Government Documents Department

Atom-to-continuum methods for gaining a fundamental understanding of fracture.

Description: This report describes an Engineering Sciences Research Foundation (ESRF) project to characterize and understand fracture processes via molecular dynamics modeling and atom-to-continuum methods. Under this aegis we developed new theory and a number of novel techniques to describe the fracture process at the atomic scale. These developments ranged from a material-frame connection between molecular dynamics and continuum mechanics to an atomic level J integral. Each of the developments build upon each other and culminated in a cohesive zone model derived from atomic information and verified at the continuum scale. This report describes an Engineering Sciences Research Foundation (ESRF) project to characterize and understand fracture processes via molecular dynamics modeling and atom-to-continuum methods. The effort is predicated on the idea that processes and information at the atomic level are missing in engineering scale simulations of fracture, and, moreover, are necessary for these simulations to be predictive. In this project we developed considerable new theory and a number of novel techniques in order to describe the fracture process at the atomic scale. Chapter 2 gives a detailed account of the material-frame connection between molecular dynamics and continuum mechanics we constructed in order to best use atomic information from solid systems. With this framework, in Chapter 3, we were able to make a direct and elegant extension of the classical J down to simulations on the scale of nanometers with a discrete atomic lattice. The technique was applied to cracks and dislocations with equal success and displayed high fidelity with expectations from continuum theory. Then, as a prelude to extension of the atomic J to finite temperatures, we explored the quasi-harmonic models as efficient and accurate surrogates of atomic lattices undergoing thermo-elastic processes (Chapter 4). With this in hand, in Chapter 5 we provide evidence that, by using the appropriate energy potential, the ...
Date: August 1, 2011
Creator: McDowell, David Lynn (Georgia Institute of Technology, Atlanta, GA); Reedy, Earl David, Jr.; Templeton, Jeremy Alan; Jones, Reese E.; Moody, Neville Reid; Zimmerman, Jonathan A. et al.
Partner: UNT Libraries Government Documents Department

Ramp-up of CHI Initiated Plasmas on NSTX

Description: Experiments on the National Spherical Torus (NSTX) have now demonstrated flux savings using transient coaxial helicity injection (CHI). In these discharges, the discharges initiated by CHI are ramped up with an inductive transformer and exhibit higher plasma current than discharges without the benefit of CHI initiation.
Date: October 29, 2009
Creator: Mueller, D; Bell, R E; LeBlanc, B; Roquemore, A L; Raman, R; Jarboe, T R et al.
Partner: UNT Libraries Government Documents Department

Wave Propagation in Jointed Geologic Media

Description: Predictive modeling capabilities for wave propagation in a jointed geologic media remain a modern day scientific frontier. In part this is due to a lack of comprehensive understanding of the complex physical processes associated with the transient response of geologic material, and in part it is due to numerical challenges that prohibit accurate representation of the heterogeneities that influence the material response. Constitutive models whose properties are determined from laboratory experiments on intact samples have been shown to over-predict the free field environment in large scale field experiments. Current methodologies for deriving in situ properties from laboratory measured properties are based on empirical equations derived for static geomechanical applications involving loads of lower intensity and much longer durations than those encountered in applications of interest involving wave propagation. These methodologies are not validated for dynamic applications, and they do not account for anisotropic behavior stemming from direcitonal effects associated with the orientation of joint sets in realistic geologies. Recent advances in modeling capabilities coupled with modern high performance computing platforms enable physics-based simulations of jointed geologic media with unprecedented details, offering a prospect for significant advances in the state of the art. This report provides a brief overview of these modern computational approaches, discusses their advantages and limitations, and attempts to formulate an integrated framework leading to the development of predictive modeling capabilities for wave propagation in jointed and fractured geologic materials.
Date: December 17, 2009
Creator: Antoun, T
Partner: UNT Libraries Government Documents Department

New perspectives on the damage estimation for buried pipeline systems due to seismic wave propagation

Description: Over the past three decades, seismic fragility fonnulations for buried pipeline systems have been developed following two tendencies: the use of earthquake damage scenarios from several pipeline systems to create general pipeline fragility functions; and, the use of damage scenarios from one pipeline system to create specific-system fragility functions. In this paper, the advantages and disadvantages of both tendencies are analyzed and discussed; in addition, a summary of what can be considered the new challenges for developing better pipeline seismic fragility formulations is discussed. The most important conclusion of this paper states that more efforts are needed to improve the estimation of transient ground strain -the main cause of pipeline damage due to seismic wave propagation; with relevant advances in that research field, new and better fragility formulations could be developed.
Date: January 1, 2009
Creator: Pineda Porras, Omar Andrey
Partner: UNT Libraries Government Documents Department

Dynamical Study of Guest-Host Orientational Interaction in LiquidCrystalline Materials

Description: Guest-host interaction has long been a subject of interest in many disciplines. Emphasis is often on how a small amount of guest substance could significantly affect the properties of a host material. This thesis describe our work in studying a guest-host effect where dye-doping of liquid crystalline materials greatly enhances the optical Kerr nonlinearity of the material. The dye molecules, upon excitation and via intermolecular interaction, provides an extra torque to reorient the host molecules, leading to the enhanced optical Kerr nonlinearity. We carried out a comprehensive study on the dynamics of the photoexcited dye-doped liquid crystalline medium. Using various experimental techniques, we separately characterized the dynamical responses of the relevant molecular species present in the medium following photo-excitation, and thus were able to follow the transient process in which photo-excitation of the dye molecules exert through guest-host interaction a net torque on the host LC material, leading to the observed enhanced molecular reorientation. We also observed for the first time the enhanced reorientation in a pure liquid crystal system, where the guest population is created through photoexcitation of the host molecules themselves. Experimental results agree quantitatively with the time-dependent theory based on a mean-field model of the guest-host interaction.
Date: December 20, 2005
Creator: Truong, Thai Viet
Partner: UNT Libraries Government Documents Department