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Chaotic behavior control in fluidized bed systems using artificial neural network. Quarterly progress report, October 1, 1996--December 31, 1996 (open access)

Chaotic behavior control in fluidized bed systems using artificial neural network. Quarterly progress report, October 1, 1996--December 31, 1996

Pressurized fluidized-bed combustors (FBC) are becoming very popular, efficient, and environmentally acceptable replica for conventional boilers in Coal-fired and chemical plants. In this paper, we present neural network-based methods for chaotic behavior monitoring and control in FBC systems, in addition to chaos analysis of FBC data, in order to localize chaotic modes in them. Both of the normal and abnormal mixing processes in FBC systems are known to undergo chaotic behavior. Even though, this type of behavior is not always undesirable, it is a challenge to most types of conventional control methods, due to its unpredictable nature. The performance, reliability, availability and operating cost of an FBC system will be significantly improved, if an appropriate control method is available to control its abnormal operation and switch it to normal when exists. Since this abnormal operation develops only at certain times due to a sequence of transient behavior, then an appropriate abnormal behavior monitoring method is also necessary. Those methods has to be fast enough for on-line operation, such that the control methods would be applied before the system reaches a non-return point in its transients. It was found that both normal and abnormal behavior of FBC systems are chaotic. However, …
Date: February 27, 1996
Creator: Bodruzzaman, M. & Essawy, M.A.
System: The UNT Digital Library
Remote nuclear screening system for hostile environments (open access)

Remote nuclear screening system for hostile environments

A remote measurement system has been constructed for in situ gamma and beta isotopic characterization of highly radioactive nuclear material in hostile environments. A small collimated, planar CdZnTe detector is used for gamma-ray spectroscopy. Spectral resolution of 2% full width at half maximum at 662 kiloelectronvolts has been obtained remotely using rise time compensation and limited pulse shape discrimination, Isotopc measurement of high-energy beta emitters was accomplished with a ruggedized, deeply depleted, surface barrier silicon dictator. The primary function of the remote nuclear screening system is to provide fast qualitative and quantitative isotopic assessment of high-level radioactive material.
Date: February 27, 1996
Creator: Addleman, R. S.; Beck, M. A.; Blewett, G. R.; Selle, E. R.; McClellan, C. S.; Dodd, D. A. et al.
System: The UNT Digital Library
Degradation kinetics of polymers in solution: Time-dependence of molecular weight distributions. [Quarterly report, January--March 1996] (open access)

Degradation kinetics of polymers in solution: Time-dependence of molecular weight distributions. [Quarterly report, January--March 1996]

Polymer degradation occurs when polymer chains are broken under the influence of thermal, mechanical, or chemical energy. Chain-end depolymerization and random- and midpoint-chain scission are mechanisms that have been observed in liquid-phase polymer degradation. Here we develop mathematical models, unified by continuous-mixture kinetics, to show how these different mechanisms affect polymer degradation in solution. Rate expressions for the fragmentation of molecular-weight distributions (MWDs) govern the evolution of the MWDs. The governing integro-differential equations can be solved analytically for realistic conditions. Moment analysis for first-order continuous kinetics shows the temporal behavior of MWDs. Chain-end depolymerization yields monomer product and polymer molecular-weight moments that vary linearly with time. In contrast, random- and midpoint-chain scission models display exponential time behavior. The mathematical results reasonably portray experimental observations for polymer degradation. This approach, based on the time evolution of continuous distributions of chain length or molecular weight, provides a framework for interpreting several types of polymer degradation processes.
Date: February 27, 1996
Creator: McCoy, B.J. & Madras, G.
System: The UNT Digital Library
Supporting safety documentation for subsurface construction of the canister storage building below grade construction restart (open access)

Supporting safety documentation for subsurface construction of the canister storage building below grade construction restart

The supporting safety documentation for subsurface construction of the canister storage building provides the safety documentation to support Key Decision 3b for the Canister Storage Building project.
Date: February 27, 1996
Creator: Garvin, L.J.
System: The UNT Digital Library
Gas characterization system software acceptance test procedure (open access)

Gas characterization system software acceptance test procedure

This document details the Software Acceptance Testing of gas characterization systems. The gas characterization systems will be used to monitor the vapor spaces of waste tanks known to contain measurable concentrations of flammable gases.
Date: February 27, 1996
Creator: Vo, C.V.
System: The UNT Digital Library
Low sample volume part-per billion level ion chromatographic analysis (open access)

Low sample volume part-per billion level ion chromatographic analysis

ADS has developed an ion chromatographic method which enables low part-per-billion levels of analysis while minimizing liquid waste generation. This method incorporates several recent technical improvements in ion chromatographic instrumentation to achieve a ten- fold increase in sensitivity over existing ion chromatographic methods without additional analysis time or sample pre-concentration. This report outlines the method, establishes the precision and accuracy levels, and discusses the applicability of the method to waste minimization and radiation exposure reduction
Date: February 27, 1996
Creator: Ekechukwu, A.A.
System: The UNT Digital Library
Evaluating the importance of innovative heterogeneous chemistry to explain observed stratospheric ozone depletion (open access)

Evaluating the importance of innovative heterogeneous chemistry to explain observed stratospheric ozone depletion

Currently, there is a widespread search for additional heterogeneous reactions or combination of heterogeneous and homogeneous (gas-phase) reactions that could catalytically reduce ozone to observed levels. In 1992, Burley and Johnston proposed that nitrosyl sulfuric acid (NSA) NOHSO{sub 4}, is a promising heterogeneous reactant for activating HCl in sulfuric acid particles. They list several sources for producing it in the stratosphere and they carried out thermodynamic and chemical kinetic calculations at one stratospheric altitude and at one latitude. NSA has been overlooked in all previous stratospheric model calculations, even though it has been observed in stratospheric sulfate aerosols. This study makes large scale atmospheric model calculations to test the proposal by Burley and Johnston that a promising heterogeneous process for activating HCl in sulfuric acid particles is a catalytic coupled based on nitrosyl sulfuric acid (NSA). This mechanism is examined under non-volcanic and volcanic conditions representative of the recent eruption of Mt. Pinatubo. The calculations set firm limits on the range of kinetic parameters over which this heterogeneous processes would be important in the global ozone balance, and thus is a guide for where laboratory work is needed. In addition, they have derived a preliminary time-dependent integration (1980--1994) to represent …
Date: February 27, 1996
Creator: Kinnison, D. E. & Connell, P. S.
System: The UNT Digital Library
Development of design basis capacity for SNF project systems (open access)

Development of design basis capacity for SNF project systems

An estimate of the design capacity for Spent Nuclear Fuel Project systems producing Multi-Canister Overpacks is developed based on completing fuel processing in a two year period. The design basis capacity for systems relates the desired annual processing rate to potential operating inefficiencies which may be actually experienced to project a design capacity for systems. The basis for estimating operating efficiency factors is described. Estimates of the design basis capacity were limited to systems actually producing the Multi-Canister Overpack. These systems include Fuel Retrieval, K Basin SNF Vacuum Drying, Canister Storage Building support for Staging and Storage, and Hot Vacuum conditioning. The capacity of other systems are assumed to be derived from these system capacities such that systems producing a Multi-Canister Overpack are not constrained.
Date: February 27, 1996
Creator: Pajunen, A.L.
System: The UNT Digital Library
Electrical test structures replicated in silicon-on-insulator material (open access)

Electrical test structures replicated in silicon-on-insulator material

Measurements of the linewidths of submicrometer features made by different metrology techniques have frequently been characterized by differences of up to 90 nm. The purpose of the work reported here is to address the special difficulties that this phenomenon presents to the certification of reference materials for the calibration of linewidth-measurement instruments. Accordingly, a new test structure has been designed, fabricated, and undergone preliminary tests. Its distinguishing characteristics are assured cross-sectional profile geometries with known side-wall slopes, surface planarity, and compositional uniformity when it is formed in mono-crystalline material at selected orientations to the crystal lattice. To allow the extraction of electrical linewidth, the structure is replicated in a silicon film of uniform conductivity which is separated from the silicon substrate by a buried oxide layer. The utilization of a Silicon-On-Insulator (SKI) substrate further allows the selective removal of substrate material from local regions below the reference features, thus facilitating measurements by optical and electron-beam transmission microscopy. The combination of planar feature surfaces having known side-wall slopes is anticipated to eliminate factors which are believed to be responsible for methods divergence in linewidth measurements, a capability which is a prerequisite for reliable certification of the linewidths of features on reference …
Date: February 27, 1996
Creator: Cresswell, M. W.; Ghoshtagore, R. N.; Allen, R. A.; Linholm, L. W.; Villarrubia, J. S. & Sniegowski, J. J.
System: The UNT Digital Library