Microfluidic Tools for Biological Sample Preparation (open access)

Microfluidic Tools for Biological Sample Preparation

Researchers at Lawrence Livermore National Laboratory are developing means to collect and identify fluid-based biological pathogens in the forms of proteins, viruses, and bacteria. To support detection instruments, we are developing a flexible fluidic sample preparation unit. The overall goal of this Microfluidic Module is to input a fluid sample, containing background particulates and potentially target compounds, and deliver a processed sample for detection. We are developing techniques for sample purification, mixing, and filtration that would be useful to many applications including immunologic and nucleic acid assays. Sample preparation functions are accomplished with acoustic radiation pressure, dielectrophoresis, and solid phase extraction. We are integrating these technologies into packaged systems with pumps and valves to control fluid flow and investigating small-scale detection methods.
Date: April 10, 2002
Creator: Visuri, S R; Ness, K; Dzenitis, J; Benett, B; Bettencourt, K; Hamilton, J et al.
Object Type: Article
System: The UNT Digital Library
On the Development of MMCS Containing Copper with Silicon Carbide Reinforcement using Nanomaterials and Dynamic Compaction (open access)

On the Development of MMCS Containing Copper with Silicon Carbide Reinforcement using Nanomaterials and Dynamic Compaction

Metal matrix composites (MMCs) are promising engineering materials for a wide spectrum of applications. There are many possible matrix-reinforcement combinations including MMCs containing copper or copper alloy matrices [1-3]. The present study is concerned with copper reinforced with SiC particles. The materials studied here were processed from nano-scale matrix powders and consolidated using dynamic compaction.
Date: April 10, 2002
Creator: Popov, V A; Lesuer, D R; Kotov, I A; Ivanov, V V; Smirnov, O M; Marmulev, A V et al.
Object Type: Article
System: The UNT Digital Library
Sorptive Polymers and Photopatterned Films for Gas Phase Chemical Microsensors and Arrays (open access)

Sorptive Polymers and Photopatterned Films for Gas Phase Chemical Microsensors and Arrays

Chemical sensors using interactive sorptive materials typically involve a ''two-step'' response mechanism. While the sorptive material collects and concentrates gas phase molecules, the device on which it has been applied transduces the presence of these sorbed molecules into an analytical signal. Usually, the sorptive material is a thin film and the device is a microfabricated structure, although other configurations exist. The film of a sorptive material is often referred to as the ''selective layer''. This general concept for gas phase chemical sensing is shown. The selective layer on a gas phase chemical microsensor plays a critical role in the sensitivity and selectivity of the sensor's response. Polymers can rapidly and reversibly absorb vapor molecules. As sorptive layers on chemical sensors, polymers are useful for a variety of chemical microsensor types and transduction mechanisms, either as is or as composites with conductive particles or dyes. The performance requirements for polymers are described in terms of their chemical and physical properties. A versatile synthetic approach for preparing sensing polymers has been developed using hydrosilylation chemistry to prepare carbosiloxane polymers. Polymers with diverse chemical selectivities have been prepared by this method. Furthermore, sorptive polymer materials can be photopatterned into defined areas on surfaces …
Date: December 10, 2002
Creator: Grate, Jay W. & Nelson, D A.
Object Type: Report
System: The UNT Digital Library
Groundwater Monitoring Plan for the 216-S-10 Pond and Ditch (open access)

Groundwater Monitoring Plan for the 216-S-10 Pond and Ditch

This report describes a groundwater monitoring plan for the 216-S-10 pond and ditch on the Hanford Site. This plan complies with the requirements of RCRA, CERCLA, and 40 CFR 265. This plan provides DOE with a revised detection monitoring well network and updates the list of constituents based on the knowledge gained from data collected over the years.
Date: October 10, 2002
Creator: Williams, Bruce A. & Chou, Charissa J.
Object Type: Report
System: The UNT Digital Library
Imaging Collagen Orientation Using Polarization-Modulated Second Harmonic Generation (open access)

Imaging Collagen Orientation Using Polarization-Modulated Second Harmonic Generation

We use polarization-modulated second harmonic generation to image fiber orientation in collagen tissues, with an axial resolution of about 10 {micro}m and a transverse resolution of up to 1 {micro}m. A linearly polarized ultra-short pulse (200 fs) Ti:Sapphire laser beam is modulated using an electro-optic modulator and quarter-wave plate combination and focused onto a translation stage mounted sample using a microscope objective. The generated second harmonic light is collected using a photomultiplier tube and demodulated using phase sensitive detection to obtain signal intensity and fiber orientation information. In order to obtain second harmonic generation images of different types of collagen organization, we analyze several different tissues, including rat-tail tendon, mouse aorta, mouse fibrotic liver, and porcine skin. We can use our technique to image fibrotic tissue in histological sections of damaged liver and to identify burned tissue in porcine skin to a depth of a few hundred microns. Polarization-modulated second harmonic generation potentially could be a useful clinical technique for diagnosing collagen related disease or damage, especially in the skin.
Date: January 10, 2002
Creator: Stoller, P; Celliers, P M; Reiser, K M & Rubenchik, A M
Object Type: Article
System: The UNT Digital Library
Java Performance for Scientific Applications on LLNL Computer Systems (open access)

Java Performance for Scientific Applications on LLNL Computer Systems

Languages in use for high performance computing at the laboratory--Fortran (f77 and f90), C, and C++--have many years of development behind them and are generally considered the fastest available. However, Fortran and C do not readily extend to object-oriented programming models, limiting their capability for very complex simulation software. C++ facilitates object-oriented programming but is a very complex and error-prone language. Java offers a number of capabilities that these other languages do not. For instance it implements cleaner (i.e., easier to use and less prone to errors) object-oriented models than C++. It also offers networking and security as part of the language standard, and cross-platform executables that make it architecture neutral, to name a few. These features have made Java very popular for industrial computing applications. The aim of this paper is to explain the trade-offs in using Java for large-scale scientific applications at LLNL. Despite its advantages, the computational science community has been reluctant to write large-scale computationally intensive applications in Java due to concerns over its poor performance. However, considerable progress has been made over the last several years. The Java Grande Forum [1] has been promoting the use of Java for large-scale computing. Members have introduced efficient …
Date: May 10, 2002
Creator: Kapfer, C. & Wissink, A.
Object Type: Report
System: The UNT Digital Library
RPF: An Extensible, Cross-Platform, Binary File Format for Radiation Physics Data (open access)

RPF: An Extensible, Cross-Platform, Binary File Format for Radiation Physics Data

Lawrence Livermore National Laboratory's Radiation Technology Group (RTG) uses a number of computer codes for simulation and analysis of radiation data. The number of incompatible data formats that these data presented themselves in have continued to multiply. In the 1980's a Common Data Format (CDF, see Appendix A) was devised for internal use by the RTG. This format represented a single gamma-ray spectrum as ASCII energy/count pairs preceded by an ASCII header. The ASCII representation of the data assured that it was compatible on any computing platform and this format is still in use. In the mid 1990's it became apparent that instrument systems of greater complexity would demand a file format of larger capacity to support systems then on the drawing board, including networks of sensors collecting time series of gamma-ray spectra. These systems were in the planning stage and defined data structures were not available. It became apparent that a new storage format for nuclear measurements data would be needed and it would have to be flexible and extensible to accommodate the requirements of systems of the future. As part of an LDRD, we began to investigate what others were doing, especially in the high-energy physics community, to …
Date: September 10, 2002
Creator: Ham, Cheryl L.
Object Type: Report
System: The UNT Digital Library
Heat transfer on D Zero Run2b stave (open access)

Heat transfer on D Zero Run2b stave

The temperature distribution on the silicon sensors and the cooling system performance for the D0 Run2b stave have been investigated. The tests have been carried out on a carbon fiber skin only stave, with and without heat input at two different chiller temperatures (-9.1 C and -19.1 C). For a bulk temperature of -14.5 C and a 14W total heat load, the stave surface has reached a peak temperature of +3.3 C, localized under the readout chip. The ''hot spot'' in the hybrid region extends about twice the length of the hybrid with an average temperature of about -4.6 C over this area. Beyond this the stave surface has a uniform temperature of -11.5 C. The film coefficient of the coolant has been calculated to be about 650W/m{sup 2}K using these measurements. A finite element analysis has confirmed the analytical calculations, providing a temperature profile consistent with what has been experimentally observed. A further finite element study has been performed in order to predict the temperature distribution in the actual stave design (46mm wide; kapton core skin; 950 {micro}m thick hybrid; 7.2mm x 1.8mm tube inner size; -15 C bulk temperature; 700W/m{sup 2}K film coefficient). The silicon temperature ranges from …
Date: April 10, 2002
Creator: Lanfranco, Giobatta
Object Type: Report
System: The UNT Digital Library
Developing High Brightness and High Current Beams for HIF Injectors (open access)

Developing High Brightness and High Current Beams for HIF Injectors

The US Heavy Ion Fusion Virtual National Laboratory is continuing research into ion sources and injectors that simultaneously provide high current (0.5-1.0 Amps) and high brightness (normalized emittance better than 1.0 {pi}-mm-mr). The central issue of focus is whether to carry on the traditional approach of large surface ionization sources or to adopt a multi-aperture approach that transports many smaller ''beamlets'' separately at low energies before allowing them to merge. For the large surface source, the recent commissioning of the 2-MeV injector for the High Current experiment has increased our understanding of the beam quality limitations for these sources. We have also improved our techniques for fabricating large diameter aluminosilicate sources to improve lifetime and emission uniformity. For the multi-aperture approach we are continuing to study the feasibility of small surface sources and a RF induced plasma source in preparation for beamlet merging experiments, while continuing to run computer simulations for better understanding of this alternate concept. Experiments into both architectures will be performed on a newly commissioned ion source test stand at LLNL called the STS-500. This stand test provides a platform for testing a variety of ion sources and accelerating structures with 500 kV, 17-microsecond pulses. Recent progress …
Date: May 10, 2002
Creator: Ahle, L & Kwan, J W
Object Type: Article
System: The UNT Digital Library
Ribbon Fiber Laser-Theory and Experiment (open access)

Ribbon Fiber Laser-Theory and Experiment

A scalable fiber laser approach is described based on phase-locking multiple gain cores in an antiguided structure. The waveguide is comprised of periodic sequences of gain- and no-gain-loaded segments having uniform index, within the cladding region. Initial experimental results are presented.
Date: May 10, 2002
Creator: Beach, R J; Feit, M D; Brasure, L D & Payne, S A
Object Type: Article
System: The UNT Digital Library
A Programmable MicroFluidic Processor: Integrated and Hybrid Solutions (open access)

A Programmable MicroFluidic Processor: Integrated and Hybrid Solutions

The Programmable Fluidic Processor (PFP), a device conceived of by researchers at MD Anderson Cancer Center, is a reconfigurable and programmable bio-chemical analysis system designed for handheld operation in a variety of applications. Unlike most microfluidic systems which utilize channels to control fluids, the PFP device is a droplet-based system. The device is based on dielectrophoresis; a fluid transport phenomenon that utilizes mismatched polarizability between a droplet and its medium to induce droplet mobility. In the device, sample carrying droplets are polarized by an array of electrodes, individually addressable by subsurface microelectronics. My research focused on the development of a polymer-based microfluidic injection system for injecting these droplets onto the electrode array. The first of two device generations fabricated at LLNL was designed using extensive research and modeling performed by MD Anderson and Coventor. Fabricating the first generation required several iterations and design changes in order to generate an acceptable device for testing. Difficulties in planar fabrication of the fluidic system and a narrow channel design necessitated these changes. The second generation device incorporated modifications of the previous generation and improved on deficiencies discovered during experimentation with the initial device. Extensive modeling of the injection channels and fluid storage chamber …
Date: May 10, 2002
Creator: Rose, K A
Object Type: Report
System: The UNT Digital Library
Atmospheric Release Assessment Program (ARAP) Science and Technology Base Development (open access)

Atmospheric Release Assessment Program (ARAP) Science and Technology Base Development

ARAP s integrated suite of research, development, and operational programs is focused on the creation of capabilities for predicting the consequences of atmospheric releases of hazardous materials. The foundation of ARAP lies in its science and technology base in multi-scale meteorological and dispersion modeling, field experiments, and software systems (databases, real-time data acquisition software, and remote-access tools). Scientific and technological advancements are integrated into DOENNSA s operational National Atmospheric Release Advisory Center (NARAC) at LLNL to support emergency response, pre-event planning, preparedness, and consequence analysis. Some recent ARAP development highlights are described below.
Date: May 10, 2002
Creator: Ermak, D L; Sugiyama, G & Nasstrom, J S
Object Type: Report
System: The UNT Digital Library
Low-Dispersion Optical Fiber Highly Tranparent in the UV Spectral Range (open access)

Low-Dispersion Optical Fiber Highly Tranparent in the UV Spectral Range

The fiber transport of sub-nanosecond laser pulses in the ultraviolet spectral region over significant distances, such as those found in the National Ignition Facility, requires special fibers. The National Ignition Facility (NIF) is a 192 arm, Nd-doped, phosphate glass laser that is being built for the US Department of Energy by and at the Lawrence Livermore National Laboratory (LLNL). This facility will be used for Inertial Confinement Fusion (ICF) research. The ultraviolet (UV) light used for target irradiation is generated at the entrance to the target chamber by converting the fundamental laser wavelength to the third harmonic (351 nm). The NIF Laser Diagnostic System's power diagnostic measures the UV laser power produced by each of the 192 arms. In this system, the diagnostic samples the laser pulse at the target chamber and a fiber transports this signal to detection and recording instrumentation located outside the target room. Pulses from four arms are delayed and multiplexed into a vacuum photodiode detector; a high bandwidth transient digitizer records the data. This basic structure is duplicated many times within the power diagnostic system.
Date: September 10, 2002
Creator: Ermolaeva, G. M.; Eron yan, M. A.; Dukel skii, K. V.; Komarov, A. V.; Kondratev, Yu. N.; Serkov, M. M. et al.
Object Type: Article
System: The UNT Digital Library
Estimating Field-Scale Hydraulic Parameters of Heterogeneous Soils Using A Combination of Parameter Scaling and Inverse Methods (open access)

Estimating Field-Scale Hydraulic Parameters of Heterogeneous Soils Using A Combination of Parameter Scaling and Inverse Methods

As the Hanford Site transitions into remediation of contaminated soil waste sites and tank farm closure, more information is needed about the transport of contaminants as they move through the vadose zone to the underlying water table. The hydraulic properties must be characterized for accurate simulation of flow and transport. This characterization includes the determination of soil texture types, their three-dimensional distribution, and the parameterization of each soil texture. This document describes a method to estimate the soil hydraulic parameter using the parameter scaling concept (Zhang et al. 2002) and inverse techniques. To this end, the Groundwater Protection Program Science and Technology Project funded vadose zone transport field studies, including analysis of the results to estimate field-scale hydraulic parameters for modeling. Parameter scaling is a new method to scale hydraulic parameters. The method relates the hydraulic-parameter values measured at different spatial scales for different soil textures. Parameter scaling factors relevant to a reference texture are determined using these local-scale parameter values, e.g., those measured in the lab using small soil cores. After parameter scaling is applied, the total number of unknown variables in hydraulic parameters is reduced by a factor equal to the number of soil textures. The field-scale values …
Date: December 10, 2002
Creator: Zhang, Z. F.; Ward, Andy L. & Gee, Glendon W.
Object Type: Report
System: The UNT Digital Library
Level Densities and Radiative Strength Functions in 56FE and 57FE (open access)

Level Densities and Radiative Strength Functions in 56FE and 57FE

Understanding nuclear level densities and radiative strength functions is important for pure and applied nuclear physics. Recently, the Oslo Cyclotron Group has developed an experimental method to extract level densities and radiative strength functions simultaneously from the primary {gamma} rays after a light-ion reaction. A primary {gamma}-ray spectrum represents the {gamma}-decay probability distribution. The Oslo method is based on the Axel-Brink hypothesis, according to which the primary {gamma}-ray spectrum is proportional to the product of the level density at the final energy and the radiative strength function. The level density and the radiative strength function are fit to the experimental primary {gamma}-ray spectra, and then normalized to known data. The method works well for heavy nuclei. The present measurements extend the Oslo method to the lighter mass nuclei {sup 56}Fe and {sup 57}Fe. The experimental level densities in {sup 56}Fe and {sup 57}Fe reveal step structure. This step structure is a signature for nucleon pair breaking. The predicted pairing gap parameter is in good agreement with the step corresponding to the first pair breaking. Thermodynamic quantities for {sup 56}Fe and {sup 57}Fe are derived within the microcanonical and canonical ensembles using the experimental level densities. Energy-temperature relations are considered using …
Date: December 10, 2002
Creator: Tavukcu, E
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Program Plan for Acquiring and Examining Naturally Aged Materials and Components from Nuclear Reactors (open access)

Program Plan for Acquiring and Examining Naturally Aged Materials and Components from Nuclear Reactors

This project was funded through the Nuclear Plant Optimization Program (NEPO)to develop an integrated plan to indentify aging issues that can be effectively addressed by investigating the condition of naturally aged components, materials,and structures (CMSs)from nuclear power plants (NPPs. As operating periods for the NPPs increase, there is a need to access selected CMSs for continuing assurance that aging issues are understood and effectively managed; also, that benchmarking of existing models is updated. A preliminary list of aging CMSs is provided for selection of candidates as NPPs are shut down or as opportunities arise to obtain CMS data from operating plants. The list is subject to revisions, based on consensus judgements regarding the most important aging issues. Further updates will arise as certain aging issues are resolved and as new issues may emerge.
Date: July 10, 2002
Creator: Johnson, A. Burton; Sundaram, S. K. & Garner, Francis A.
Object Type: Report
System: The UNT Digital Library
RF Curves for Extraction from the Accumulator (open access)

RF Curves for Extraction from the Accumulator

Since the start of Run IIa, the RF curves for the extraction process from the Accumulator have been based on an algorithm described in Pbar Note 636. There are a number of problems with this procedure that result in a dilution of the longitudinal phase space of the extracted beam. The procedure consists of a number of steps in which the frequency curve during each process is a linear time ramp. For a constant bend field, the synchronous phase angle is given as: {Lambda} = sin({phi}{sub s}) = -h/{eta} (1/f{sub rf}){sup 2}df{sub rf}/dt/qV/pc where h is the harmonic number of the RF. Equation (1) shows that if the frequency curve consists of a number of linear time ramps with different slopes, there will be discontinuities in the synchronous phase. These discontinuities in the synchronous phase will lead to dipole oscillations of the beam in the RF bucket. The discontinuities observed for the present RF curves are about 10 degrees. In the procedure outlined in Pbar Note 636, the RF bucket is formed on the high energy edge of the rectangular momentum distribution. As the RF bucket is pulled away from the core, it is also programmed to increase in area. …
Date: March 10, 2002
Creator: McGinnis, Dav
Object Type: Report
System: The UNT Digital Library
Grand Unification in Higher Dimensions (open access)

Grand Unification in Higher Dimensions

We have recently proposed an alternative picture for the physics at the scale of gauge coupling unification, where the unified symmetry is realized in higher dimensions but is broken locally by a symmetry breaking defect. Gauge coupling unification, the quantum numbers of quarks and leptons and the longevity of the proton arise as phenomena of the symmetrical bulk, while the lightness of the Higgs doublets and the masses of the light quarks and leptons probe the symmetry breaking defect. Moreover, the framework is extremely predictive if the effective higher dimensional theory is valid over a large energy interval up to the scale of strong coupling. Precise agreement with experiments is obtained in the simplest theory --- SU(5) in five dimensions with two Higgs multiplets propagating in the bulk. The weak mixing angle is predicted to be sin^2theta_w = 0.2313 \pm 0.0004, which fits the data with extraordinary accuracy. The compactification scale and the strong coupling scale are determined to be M_c \simeq 5 x 10^14 GeV and M_s \simeq 1 x 10^17 GeV, respectively. Proton decay with a lifetime of order 10^{34} years is expected with a variety of final states such as e^+pi^0, and several aspects of flavor, including …
Date: December 10, 2002
Creator: Hall, Lawrence J. & Nomura, Yasunori
Object Type: Article
System: The UNT Digital Library
Formation and Reactivity of Biogenic Iron Microminerals (open access)

Formation and Reactivity of Biogenic Iron Microminerals

Radionuclide and heavy metal contaminants at DOE sites pose immediate and long-term environmental problems. Under the NABIR program, bacteria are being considered for their role in the cycling of these contaminants because they influence many redox reactions in the subsurface. Dissimilatory metal reducing bacteria (DMRB) are particularly important to controlling the biogeochemistry of subsurface environments through enzymatic reduction of iron and manganese minerals. During reduction of FeIII, biogenic FeII phases form at the cell-mineral interface which may profoundly influence metal reduction.
Date: August 10, 2002
Creator: Beveridge, Terrance J. & Ferris, F. Grant
Object Type: Report
System: The UNT Digital Library
Determination of Importance Evaluation for Exploratory Studies Facility (ESF) Subsurface Testing Activities (open access)

Determination of Importance Evaluation for Exploratory Studies Facility (ESF) Subsurface Testing Activities

None
Date: May 10, 2002
Creator: Goodin, S.
Object Type: Report
System: The UNT Digital Library
Advanced Chemistry Basins Model (open access)

Advanced Chemistry Basins Model

The DOE-funded Advanced Chemistry Basin model project is intended to develop a public domain, user-friendly basin modeling software under PC or low end workstation environment that predicts hydrocarbon generation, expulsion, migration and chemistry. The main features of the software are that it will: (1) afford users the most flexible way to choose or enter kinetic parameters for different maturity indicators; (2) afford users the most flexible way to choose or enter compositional kinetic parameters to predict hydrocarbon composition (e.g., gas/oil ratio (GOR), wax content, API gravity, etc.) at different kerogen maturities; (3) calculate the chemistry, fluxes and physical properties of all hydrocarbon phases (gas, liquid and solid) along the primary and secondary migration pathways of the basin and predict the location and intensity of phase fractionation, mixing, gas washing, etc.; and (4) predict the location and intensity of de-asphaltene processes. The project has be operative for 36 months, and is on schedule for a successful completion at the end of FY 2003.
Date: November 10, 2002
Creator: Goddard, William; Blanco, Mario; Cathles, Lawrence; Manhardt, Paul; Meulbroek, Peter & Tang, Yongchun
Object Type: Report
System: The UNT Digital Library
805 MHz and 201 MHz RF cavity development for MUCOOL (open access)

805 MHz and 201 MHz RF cavity development for MUCOOL

A muon cooling channel calls for very high acceleratinggradient RF structures to restore the energy lost by muons in theabsorbers. The RF structures have to be operated in a strong magneticfield and thus the use of superconducting RF cavities is excluded. Toachieve a high shunt impedance while maintaining a large enough apertureto accommodate a large transverse emittance muon beam, the cavity designadopted is a pillbox-like geometry with thin Be foils to terminate theelectromagnetic field at the cavity iris. The possibility of using gridsof thin-walled metallic tubes for the termination is also being explored.Many of the RF-related issues for muon cooling channels are being studiedboth theoretically and experimentally using an 805 MHz cavity that has apillbox-like geometry with thin Be windows to terminate the cavityaperture. The design and performance of this cavity are reported here.High-power RF tests of the 805 MHz cavity are in progress at Lab G inFermilab. The cavity has exceeded its design gradient of 30 MV/m,reaching 34 MV/m without external magnetic field. No surface damage wasobserved at this gradient. The cavity is currently under conditioning atLab G with an external magnetic field of 2.5 T. We also present here a201 MHz cavity design for muoncooling channels. The proposed …
Date: October 10, 2002
Creator: DLi@lbl.gov
Object Type: Article
System: The UNT Digital Library
Development of Low Cost Carbonaceous Materials for Anodes in Lithium-Ion Batteries for Electric and Hybrid Electric Vehicles (open access)

Development of Low Cost Carbonaceous Materials for Anodes in Lithium-Ion Batteries for Electric and Hybrid Electric Vehicles

Final report on the US DOE CARAT program describes innovative R & D conducted by Superior Graphite Co., Chicago, IL, USA in cooperation with researchers from the Illinois Institute of Technology, and defines the proper type of carbon and a cost effective method for its production, as well as establishes a US based manufacturer for the application of anodes of the Lithium-Ion, Lithium polymer batteries of the Hybrid Electric and Pure Electric Vehicles. The three materials each representing a separate class of graphitic carbon, have been developed and released for field trials. They include natural purified flake graphite, purified vein graphite and a graphitized synthetic carbon. Screening of the available on the market materials, which will help fully utilize the graphite, has been carried out.
Date: December 10, 2002
Creator: Barsukov, Igor V.
Object Type: Report
System: The UNT Digital Library
Estimating equivalent dipole polarizabilities for the inductiveresponse of isolated conductive bodies (open access)

Estimating equivalent dipole polarizabilities for the inductiveresponse of isolated conductive bodies

Equivalent dipole polarizability matrices and equivalent dipole location are a convenient way to interpret magnetic field data due to currents induced in isolated conductive objects. The uncertainties in polarizability estimates and in equivalent dipole location provide a quantitative measure of the performance of different configurations of transmitters and receivers. These uncertainties are estimated using a linearized inversion (Smith and Morrison, 2002). For many systems, consisting of one or more rectangular loop transmitters and a number of dipole receivers, sited on a horizontal grid, equivalent dipole depth is determined to 10% accuracy to depths approximately 20% deeper, than the depths at which polarizability matrix elements can be determined to the same precision. Systems that have a lower product of rms polarizability uncertainty and square root of their number of transmitter-receiver pairs are considered more effective for the number of transmitter-receiver pairs. Among the systems studied, a system with three orthogonal transmitter loops and a three component receiver is the most effective, for objects shallower than 0.6 times the instrument siting grid spacing, yielding an rms polarizability uncertainty 0.04 times that of a single transmitter single receiver system. At intermediate depths, a system with two vertical component receivers on the diagonal of …
Date: October 10, 2002
Creator: Smith, J. Torquil & Morrison, H. Frank
Object Type: Article
System: The UNT Digital Library