Showing papers by "General Electric published in 2006"

Person Reidentification Using Spatiotemporal Appearance

Abstract: In many surveillance applications it is desirable to determine if a given individual has been previously observed over a network of cameras. This is the person reidentification problem. This paper focuses on reidentification algorithms that use the overall appearance of an individual as opposed to passive biometrics such as face and gait. Person reidentification approaches have two aspects: (i) establish correspondence between parts, and (ii) generate signatures that are invariant to variations in illumination, pose, and the dynamic appearance of clothing. A novel spatiotemporal segmentation algorithm is employed to generate salient edgels that are robust to changes in appearance of clothing. The invariant signatures are generated by combining normalized color and salient edgel histograms. Two approaches are proposed to generate correspondences: (i) a model based approach that fits an articulated model to each individual to establish a correspondence map, and (ii) an interest point operator approach that nominates a large number of potential correspondences which are evaluated using a region growing scheme. Finally, the approaches are evaluated on a 44 person database across 3 disparate views.

Combinatorial search of thermoelastic shape-memory alloys with extremely small hysteresis width

Abstract: Reversibility of structural phase transformations has profound technological implications in a wide range of applications from fatigue life in shape-memory alloys (SMAs) to magnetism in multiferroic oxides. The geometric nonlinear theory of martensite universally applicable to all structural transitions has been developed. It predicts the reversibility of the transitions as manifested in the hysteresis behaviour based solely on crystal symmetry and geometric compatibilities between phases. In this article, we report on the verification of the theory using the high-throughput approach. The thin-film composition-spread technique was devised to rapidly map the lattice parameters and the thermal hysteresis of ternary alloy systems. A clear relationship between the hysteresis and the middle eigenvalue of the transformation stretch tensor as predicted by the theory was observed for the first time. We have also identified a new composition region of titanium-rich SMAs with potential for improved control of SMA properties.

Transition Modelling for General Purpose CFD Codes

Abstract: The paper addresses modelling concepts based on the RANS equations for laminar-turbulent transition prediction in general-purpose CFD codes. Available models are reviewed, with emphasis on their compatibility with modern CFD methods. Requirements for engineering transition models suitable for industrial CFD codes are specified. A new concept for transition modeling is introduced. It is based on the combination of experimental correlations with locally formulated transport equations. The concept is termed LCTM – Local Correlation-based Transition Model. An LCTM model, which satisfies most of the specified requirements is described, including results for a variety of different complex applications. An incremental approach was used to validate the model, first on 2D flat plates and airfoils and then on to progressively more complicated test cases such as a three-element flap, a 3D transonic wing and a full helicopter configuration. In all cases good agreement with the available experimental data was observed. The authors believe that the current formulation is a significant step forward in engineering transition modeling, as it allows the combination of transition correlations with general purpose CFD codes. There is a strong potential that the model will allow the 1st order effects of transition to be included in everyday industrial CFD simulations.

Thermochemical Interaction of Thermal Barrier Coatings with Molten CaO–MgO–Al2O3–SiO2 (CMAS) Deposits

Abstract: Thermal barrier coatings (TBCs) are increasingly susceptible to degradation by molten calcium–magnesium alumino silicate (CMAS) deposits in advanced engines that operate at higher temperatures and in environments laden with siliceous debris. This paper investigates the thermochemical aspects of the degradation phenomena using a model CMAS composition and ZrO2–7.6%YO1.5 (7YSZ) grown by vapor deposition on alumina substrates. The changes in microstructure and chemistry are characterized after isothermal treatments of 4 h at 1200°–1400°C. It is found that CMAS rapidly penetrates the open structure of the coating as soon as melting occurs, whereupon the original 7YSZ dissolves in the CMAS and reprecipitates with a different morphology and composition that depends on the local melt chemistry. The attack is minimal in the bulk of the coating but severe near the surface and the interface with the substrate, which is also partially dissolved by the melt. The phase evolution is discussed in terms of available thermodynamic information.

Crystal Chemistry and Luminescence of Ce3+-Doped Lu2CaMg2(Si,Ge)3O12 and Its Use in LED Based Lighting

Abstract: In this paper, we describe the formation and luminescence of a new garnet phosphor for light emitting diode (LED) based lighting, Lu2CaMg2(Si,Ge)3O12:Ce3+. The regions for garnet phase formation are initially described with respect to larger rare earth substitution and show reasonable correlation to previous crystal chemistry studies for the garnet parent structure. While the pure silicate phosphor also has apatite second phases, a significant amount of Ce3+ enters the garnet phase, giving Ce3+ luminescence that is significantly redder when compared to typical Al3+ garnet phosphors with quantum efficiencies comparable to commercial Ce3+ garnet phosphors. Potential reasons for the emission red shift and the high quantum efficiency are discussed. Finally, the performance of these new phosphors is tested within LED based lamps. Lamps using these phosphors can reach color temperatures required for general illumination lighting and also have comparable phosphor conversion efficiencies when compared to lamps us...

Multi-Object Tracking Through Simultaneous Long Occlusions and Split-Merge Conditions

Abstract: A fundamental requirement for effective automated analysis of object behavior and interactions in video is that each object must be consistently identified over time. This is difficult when the objects are often occluded for long periods: nearly all tracking algorithms will terminate a track with loss of identity on a long gap. The problem is further confounded by objects in close proximity, tracking failures due to shadows, etc. Recently, some work has been done to address these issues using higher level reasoning, by linking tracks from multiple objects over long gaps. However, these efforts have assumed a one-to-one correspondence between tracks on either side of the gap. This is often not true in real scenarios of interest, where the objects are closely spaced and dynamically occlude each other, causing trackers to merge objects into single tracks. In this paper, we show how to efficiently handle splitting and merging during track linking. Moreover, we show that we can maintain the identities of objects that merge together and subsequently split. This enables the identity of objects to be maintained throughout long sequences with difficult conditions. We demonstrate our approach on a highly challenging, oblique-view video sequence of dense traffic of a highway interchange. We successfully track the large majority of the hundreds of moving vehicles in the scene, many in close proximity, through long occlusions and shadows.

A Correlation-Based Transition Model using Local Variables

Abstract: A new correlation-based transition model has been developed, which is based strictly on local variables. As a result, the transition model is compatible with modern computational fluid dynamics (CFD) approaches, such as unstructured grids and massive parallel execution. The model is based on two transport equations, one for intermittency and one for the transition onset criteria in terms of momentum thickness Reynolds number. The proposed transport equations do not attempt to model the physics of the transition process (unlike, e.g., turbulence models) but from a framework for the implementation of correlation-based models into general-purpose CFD methods.

Gas turbine engine assembly and methods of assembling same

Abstract: A gas turbine engine assembly (10), includes a core gas turbine engine (12), a low-pressure turbine (14) coupled to the core turbine engine, a counter-rotating fan assembly (16) coupled to the low-pressure turbine, and a booster compressor (24) coupled directly to the low-pressure turbine such that the booster compressor and the low-pressure turbine rotate in the same direction.

An improved control strategy for grid-connected voltage source inverters with a LCL filter

Abstract: This paper proposes a novel control strategy for grid-connected voltage source inverters (VSI) with an LCL-filter. The strategy "split" the capacitor of LCL-filter into two parts, and the current flowing between these two parts is measured and used as the feedback of a current regulator to stabilize and improve the system performances. By this way, the inverter control system is simplified from third-order to first-order, and the close loop control system can easily be optimized for minimum steady-state error and current harmonic distortion. The characteristics of the inverter system with the proposed controller are investigated and compared with the traditional strategy. Simulations results are provided, and the new current control strategy has been experimentally tested on a 5kW fuel cell inverter.

Fault Detection in a Multistage Gearbox by Demodulation of Motor Current Waveform

Abstract: Demodulation of vibration signal to detect faults in machinery has been a prominent prevalent technique that is discussed by a number of authors. This paper deals with the demodulation of the current signal of an induction motor driving a multistage gearbox for its fault detection. This multistage gearbox has three gear ratios, and thus, three rotating shafts and their corresponding gear mesh frequencies (GMFs). The gearbox is loaded electrically by a generator feeding an electrical resistance bank. Amplitude demodulation and frequency demodulation are applied to the current drawn by the induction motor for detecting the rotating shaft frequencies and GMFs, respectively. Discrete wavelet transform is applied to the demodulated current signal for denoising and removing the intervening neighboring features. Spectrum of a particular level, which comprises the GMFs, is used for gear fault detection

Analysis of surface permanent magnet machines with fractional-slot concentrated windings

Abstract: This paper presents a closed-form analytical technique for analyzing surface PM machines equipped with fractional-slot concentrated windings. Since this class of winding configuration deviates significantly from conventional sinusoidal distributions, classical steady-state phasor or dq analytical techniques cannot be used to provide accurate results. The presented analytical model provides a fast and reliable method to analyze and compare candidate machine designs. Stator slotting effects are taken into consideration and a wide range of concentrated winding configurations can be analyzed. This technique is capable of analyzing the machine both below (constant-torque) and above (flux-weakening) base speed. Average torque, cogging torque, and ripple torque are all evaluated. Analytical results are verified using finite element analysis.

Direct Liquid Cooling of High Flux Micro and Nano Electronic Components

Abstract: The inexorable rise in chip power dissipation and emergence of on-chip hot spots with heat fluxes approaching 1 =kW/cm2 has turned renewed attention to direct cooling with dielectric liquids. Use of dielectric liquids in intimate contact with the heat dissipating surfaces eliminates the deleterious effects of solid-solid interface resistances and harnesses the highly efficient phase-change processes to the critical thermal management of advanced IC chips. In the interest of defining the state-of-the-art in direct liquid cooling, this paper begins with a discussion of the thermophysics of phase-change processes and a description of the available dielectric liquid cooling techniques and their history. It then describes the phenomenology of pool boiling, spray/jet impingement, gas-assisted evaporation, and synthetic jet impingement with dielectric liquids. Available correlations for predicting the heat transfer coefficients and limiting heat transfer rates, as well as documented empirical results for these promising techniques for on-chip hot spot cooling, are also provided and compared

Non–Small Cell Lung Cancers with Kinase Domain Mutations in the Epidermal Growth Factor Receptor Are Sensitive to Ionizing Radiation

Abstract: Non-small cell lung cancers (NSCLCs) bearing mutations in the tyrosine kinase domain (TKD) of the epidermal growth factor receptor (EGFR) often exhibit dramatic sensitivity to the EGFR tyrosine kinase inhibitors gefitinib and erlotinib. Ionizing radiation (IR) is frequently used in the treatment of NSCLC, but little is known how lung tumor-acquired EGFR mutations affect responses to IR. Because this is of great clinical importance, we investigated and found that clonogenic survival of mutant EGFR NSCLCs in response to IR was reduced 500- to 1,000-fold compared with wild-type (WT) EGFR NSCLCs. Exogenous expression of either the L858R point mutant or the DeltaE746-E750 deletion mutant form of EGFR in immortalized human bronchial epithelial cells, p53 WT NSCLC (A549), or p53-null NSCLC (NCI-H1299) resulted in dramatically increased sensitivity to IR. We show that the majority of mutant EGFR NSCLCs, including those that contain the secondary gefitinib resistance T790M mutation, exhibit characteristics consistent with a radiosensitive phenotype, which include delayed DNA repair kinetics, defective IR-induced arrest in DNA synthesis or mitosis, and pronounced increases in apoptosis or micronuclei. Thus, understanding how activating mutations in the TKD domain of EGFR contribute to radiosensitivity should provide new insight into effective treatment of NSCLC with radiotherapy and perhaps avoid emergence of single agent drug resistance.

Sealing in Turbomachinery

Abstract: Clearance control is of paramount importance to turbomachinery designers and is required to meet today's aggressive power output, efficiency, and operational life goals. Excessive clearances lead to losses in cycle efficiency, flow instabilities, and hot gas ingestion into disk cavities. Insufficient clearances limit coolant flows and cause interface rubbing, overheating downstream components and damaging interfaces, thus limiting component life. Designers have put renewed attention on clearance control, as it is often the most cost effective method to enhance system performance. Advanced concepts and proper material selection continue to play important roles in maintaining interface clearances to enable the system to meet design goals. This work presents an overview of turbomachinery sealing to control clearances. Areas covered include: characteristics of gas and steam turbine sealing applications and environments, benefits of sealing, types of standard static and dynamics seals, advanced seal designs, as well as life and limitations issues.

Equivalencing the collector system of a large wind power plant

Abstract: As the size and number of wind power plants (also called wind farms) increases, power system planners will need to study their impact on the power system in more detail. As the level of wind power penetration into the grid increases, the transmission system integration requirements becomes more critical. A very large wind power plant may contain hundreds of megawatt-size wind turbines. These turbines are interconnected by an intricate collector system. While the impact of individual turbines on the larger power system network is minimal, collectively, wind turbines can have a significant impact on the power systems during a severe disturbance such as a nearby fault. Since it is not practical to represent all individual wind turbines to conduct simulations, a simplified equivalent representation is required. This paper focuses on our effort to develop an equivalent representation of a wind power plant collector system for power system planning studies. The layout of the wind power plant, the size and type of conductors used, and the method of delivery (overhead or buried cables) all influence the performance of the collector system inside the wind power plant. Our effort to develop an equivalent representation of the collector system for wind power plants is an attempt to simplify power system modeling for future developments or planned expansions of wind power plants. Although we use a specific large wind power plant as a case study, the concept is applicable for any type of wind power plant.

Systems and methods for power generation with carbon dioxide isolation

Abstract: A power generation system includes at least one turbine system. The turbine system includes a compressor section comprising at least one stage, configured to supply a compressed oxidant and a combustion chamber configured to combust the compressed oxidant and a fuel stream comprising carbon-based fuels and to generate a hot flue gas. The turbine system further includes an expander section having an inlet for receiving the hot flue gas comprising at least two stages. The two stages include a high-pressure expander configured to generate an expanded exhaust gas rich in CO 2 . The high-pressure expander fluidly coupled to a low-pressure expander configured to generate a final exhaust and electrical energy. A CO 2 separation system is fluidly coupled to the high-pressure expander for receiving the expanded exhaust gas from the high-pressure expander and providing a CO 2 lean gas that is then fed to the low-pressure expander.

Carbon dioxide capture systems and methods

Abstract: A carbon dioxide separation system comprises a heat exchanger having a first flow path for directing a fluid comprising carbon dioxide, for example an exhaust gas, therethrough and a second flow path for directing a heat transfer fluid therethrough, a separator comprising a material with selective permeability of carbon dioxide for separating the first and second flow paths and for promoting thermal transfer and carbon dioxide transport therebetween, and a condenser for condensing the heat transfer fluid to isolate the carbon dioxide. In another embodiment, a carbon dioxide separation system comprises an energy production system for generating electricity and an exhaust gas including carbon dioxide at a temperature greater than about 300C, a heat exchanger having a first flow path for directing the exhaust gas therethrough and a second flow path for directing water therethrough to promote thermal transfer between the first flow path and the second flow path and produce a flow of steam within the second flow path, a carbon dioxide extraction circuit in thermal and mass transfer relationship with the exhaust gas comprising a third flow path for directing a heat transfer fluid therethrough, wherein the carbon dioxide extraction circuit comprises a material with selective permeability of carbon dioxide for promoting thermal transfer and carbon dioxide transport between the exhaust gas and the heat transfer fluid to produce a mixed flow of a gaseous heat transfer fluid and carbon dioxide within the third flow path, and a condenser for receiving the mixed flow and for condensing the mixed flow to isolate the carbon dioxide.

Gallium nitride crystals and wafers and method of making

Abstract: A GaN crystal having up to about 5 mole percent of at least one of aluminum, indium, and combinations thereof. The GaN crystal has at least one grain having a diameter greater than 2 mm, a dislocation density less than about 104 cm−2, and is substantially free of tilt boundaries.

X-ray ct apparatus

Abstract: A data acquisition device, which has an X-ray detector including a plurality of channel widths at which channels at its central portion are fine and channels at its peripheral portions are coarse or rough, and a plurality of data acquisition ranges including a data acquisition range wide in a channel direction and a data acquisition range narrow in the channel direction, and which is capable of performing switching among the data acquisition ranges for each data acquisition, is used to perform data acquisition on the channels fine at the central portion in the data acquisition range narrow in the channel direction, whereby an X-ray CT apparatus is provided which is capable of performing high-resolution imaging and brings about more satisfactory image quality.

Axial Turbine Blade Tips: Function, Design, and Durability

Abstract: An overview of the science and technology involved in today's turbine engines is presented with specific focus on the critical rotational-to-stationary interfaces comprising axial turbine blade tips. The purpose is to provide a concise informative review of turbine blade tip functional, design, and durability issues. Neither a historical account nor a bibliography is presented. Attention is paid primarily to the most challenging blade tips in high-pressure, high-temperature gas turbine systems, although most of the science discussed applies equally well to blade tips in low-pressure turbines, as well as steam turbines. As such, a wide range of both aircraft engine and power generating turbine systems are considered. Basic functional requirements, turbine systems design aspects, and transient operational considerations affecting blade tips and affected by blade tips are discussed in light of the multidisciplinary tradeoffs involved in a successful design. The three dominant design philosophies for blade tips in practice today are presented with detailed examination of the aerodynamics, heat transfer, and cooling benefits and detractors. Finally, the in-service durability aspects of turbine blade tips are noted.

Polymeric sensor materials: toward an alliance of combinatorial and rational design tools?

Abstract: Increased selectivity, response speed, and sensitivity in the chemical and biological determinations of gases and liquids are of great interest. Particular attention is paid to polymeric sensor materials, which are applicable to sensors exploiting various energy transduction principles, such as radiant, electrical, mechanical, and thermal energy. Ideally, numerous functional parameters of sensor materials can be tailored to meet specific needs using rational design approaches. However, increasing the structural and functional complexity of polymeric sensor materials makes it more difficult to predict the desired properties. Combinatorial and high-throughput methods have had an impact on all areas of research on polymer-based sensor materials including homo- and copolymers, formulated materials, polymeric structures with engineered morphology, and molecular shape-recognition materials. Herein we report on the state-of-the-art, the development trends, and the remaining knowledge gaps in the area of combinatorial polymeric sensor materials design.

Advanced heat sinks and thermal spreaders

Abstract: A heat sink assembly for an electronic device or a heat generating device(s) is constructed from an ultra-thin graphite layer. The ultra-thin graphite layer exhibits thermal conductivity which is anisotropic in nature and is greater than 500 W/m° C. in at least one plane and comprises at least a graphene layer. The ultra-thin graphite layer is structurally supported by a layer comprising at least one of a metal, a polymeric resin, a ceramic, and a mixture thereof, which is disposed on at least one surface of the graphite layer.

A Review of Turbine Blade Tip Heat Transfer

Abstract: This paper presents a review of the publicly available knowledge base concerning turbine blade tip heat transfer, from the early fundamental research which laid the foundations of our knowledge, to current experimental and numerical studies utilizing engine-scaled blade cascades and turbine rigs. Focus is placed on high-pressure, high-temperature axial-turbine blade tips, which are prevalent in the majority of today's aircraft engines and power generating turbines. The state of our current understanding of turbine blade tip heat transfer is in the transitional phase between fundamentals supported by engine-based experience, and the ability to a priori correctly predict and efficiently design blade tips for engine service.

Development of a PM transverse flux motor with soft magnetic composite core

Abstract: This paper reports the design, performance analysis, fabrication, and experimental results of a three-phase, three-stack permanent magnet transverse flux motor with a soft magnetic composite stator core, which was designed to take advantage of the unique properties of the new material. Parameter computations by finite element analysis of the magnetic field and performance prediction by the equivalent electric circuit are discussed. To validate the simulation, a prototype motor has been fabricated and operated with a sensorless, brushless direct coupler drive scheme. The experimental results are thoroughly presented and agree with the theoretical calculations very well.

Gas Turbine Heat Transfer: Ten Remaining Hot Gas Path Challenges

Abstract: The advancement of turbine cooling has allowed engine design to exceed normal material temperature limits, but it has introduced complexities that have accentuated the thermal issues greatly. Cooled component design has consistently trended in the direction of higher heat loads, higher through-wall thermal gradients, and higher in-plane thermal gradients. The present discussion seeks to identify ten major thermal issues, or opportunities, that remain for the turbine hot gas path (HGP) today. These thermal challenges are commonly known in their broadest forms, but some tend to be little discussed in a direct manner relevant to gas turbines. These include uniformity of internal cooling, ultimate film cooling, microcooling, reduced incident heat flux, secondary flows as prime cooling, contoured gas paths, thermal stress reduction, controlled cooling, low emission combustor-turbine systems, and regenerative cooling. Evolutionary or revolutionary advancements concerning these issues will ultimately be required in realizable engineering forms for gas turbines to breakthrough to new levels of performance. Herein lies the challenge to researchers and designers. It is the intention of this summary to provide a concise review of these issues, and some of the recent solution directions, as an initial guide and stimulation to further research.

Tissue-Like Phantoms for Near-Infrared Fluorescence Imaging System Assessment and the Training of Surgeons

Abstract: We demonstrate how to construct calibrated, stable, and inexpensive tissue-like phantoms for near-IR (NIR) fluorescence imaging applications. The bulk phantom material is composed of gelatin, intralipid, hemoglobin, and indocyanine green (ICG). Absorbance, scatter, background fluorescence, and texture can be tuned as desired. NIR fluorescent inclusions are comprised of ICG-labeled polystyrene divinylbenzene beads and Pam78-labeled hydroxyapatite crystals. The former mimic tumor masses of controllable size and contrast agent concentration, and the latter mimic microcalcifications in breast cancer. NIR-fluorescent inclusions can be positioned precisely in phantoms, with one or more regions having different optical properties, and their position can be verified independently using microcomputed tomography. We demonstrate how these phantoms can be used to calibrate and compare imaging systems, and to train surgeons to operate under NIR fluorescence image guidance.

Toward single breath-hold whole-heart coverage coronary MRA using highly accelerated parallel imaging with a 32-channel MR system.

Abstract: Coronary MR angiography (CMRA) is generally confined to the acquisition of multiple targeted slabs with coverage dictated by the competing constraints of signal-to-noise ratio (SNR), physiological motion, and scan time. This work addresses these obstacles by demonstrating the technical feasibility of using a 32-channel coil array and receiver system for highly accelerated volumetric breath-hold CMRA. The use of the 32-element array in unaccelerated CMRA studies provided a baseline SNR increase of as much as 40% over conventional cardiac-optimized phased array coils, which resulted in substantially enhanced image quality and improved delineation of the coronary arteries. Modest accelerations were used to reduce breath-hold durations for tailored coverage of the coronary arteries using targeted multi-oblique slabs to as little as 10 s. Finally, high net accelerations were combined with the SNR advantages of a 3D steady-state free precession (SSFP) technique to achieve previously unattainable comprehensive volumetric coverage of the coronary arteries in a single breath-hold. The merits and limitations of this simplified volumetric imaging approach are discussed and its implications for coronary MRA are considered.