General Electric Global Research Center Research Articles

Special issue on SoC and AI processors

Special issue on SoC and AI processors

Developing the Digital Manufacturing Commons: A National Initiative for US Manufacturing Innovation

The manufacturing sector is at the core of the American economy. With American leadership in advanced manufacturing at risk due to changes in the global economy and new competitors rising across the globe, the U.S. President announced an investment of $1 billion in a National Network for Manufacturing Innovation (NNMI). The key focus is on new technology paradigms that can improve the competitiveness of American manufacturing – with a focus on small and medium enterprises (SMEs) – through digitization of design and manufacturing, democratization of technology, and collaborative design and analytics to sustain leadership across the U.S. manufacturing ecosystem.Funded through the newly established Digital Manufacturing and Design Innovation Institute and supported through a Cooperative Agreement with the Department of Defense, the Digital Manufacturing Commons (DMC) is an open-source platform based on previous Massachusetts Institute of Technology (MIT), Defense Advanced Research Projects Agency (DARPA) and General Electric (GE) projects and built to democratize development and access to the tools for manufacturing innovation across small and large companies, universities, institutes, and entrepreneurs. The DMC will bring together one hundred thousand or more users, thousands of SMEs, large manufacturing companies, and universities to collaborate on manufacturing and to accelerate technologies that integrate the digital thread from design to manufacture and service.The initiative to build the DMC is led by GE Global Research Center. The DMC will be transitioned to the Digital Manufacturing and Design Innovation Institute and made available to the U.S. manufacturing base to enable a digital revolution in manufacturing innovation.

Nanofiller Dispersion in Polymer Dielectrics

Nanodielectric composites have been developed in recent years attempting to improve the dielectric properties such as dielectric constant, dielectric strength and voltage endurance. Among various investigations, nanoparticle dispersion was particularly emphasized in this work. General Electric Global Research Center in Niskayuna NY USA has investigated various nanoparticles, nanocomposites and nanocomposite synthesis methods intending to understand particle dispersion and their impact on the nanocomposite dielectric properties. The breakdown strength and microstructures of the nanocomposites containing different particles were studied for projects related to capacitor and electrical insulation technologies. The nanocomposite synthesis methods either employed commerical nanoparticles or utilized nanoparticles that were self-assembled (in-situ precipitation) in a matrix. Our investigations have shown that nanocomposites prepared with solution chemistry were more favorable for producing uniform dispersion of nanoparticles. Structural information of nanocomposites was studied with transmission electron microscopy and the interection between particles and matrix polymers were tentatively probed using dielectric spectroscopy. In these new class of materials high energy densities on the order of 15J/cc were achievable in nanocomposites.

Silicon Carbide Ultraviolet Photodetector Modeling, Design and Experiments

We report measurements and modeling of silicon carbide (SiC) based ultraviolet photodetectors for the detection of light in the mid-to-short ultraviolet range where SiC’s absorption coefficients are high and the corresponding penetration depths are low. These large absorption coefficients result in increased susceptibility of photo-generated electron and holes to surface recombination and therefore give rise to lower quantum efficiencies. To increase responsivity and extend the detection capability of these photodetectors to short ultraviolet wavelengths (or UVC), we measure an existing silicon carbide avalanche photodiode (APD) designed and fabricated for 280 nm operation by General Electric Global Research Center, and then develop models and techniques to increase their operation range to lower UV wavelengths. The measurements aid the development and calibration of a silicon carbide modeling and design suite that is currently being used to assist the design of a new silicon carbide APD for UVC detection. Here the design considerations require low operating voltages, low noise, low dark count rate and high responsivity. We plan to satisfy design criteria by engineering thickness and doping of stacked layers as well as by designing an APD surface that gives rise to minimal recombination of electrons and holes generated by the incident light.

On the Performance and Operability of GE’s Dry Low NO Combustors utilizing Exhaust Gas Recirculation for PostCombustion Carbon Capture

The capture and sequestration of CO2 will be necessary to mitigate CO2 emissions from fossil fuel (coal, oil, natural gas or biomass) power generation facilities in a carbon constrained world. Post combustion carbon capture is a viable technology alternative to reduce CO2 emissions from power plants in the short term. The CO2 concentration in the exhaust gases of natural fired power plants can be increased through exhaust gas recirculation (EGR). A joint CO2 Capture Project (CCP) and GE study of the Best Integrated Technology (BIT) shows that EGR enables reduced exhaust gas flow to the post combustion capture plant and cost of the CO2 capture. This paper describes the experimental work performed at General Electric Global Research Center in order to better understand the risks of utilizing EGR in combination with dry low NOx (DLN) combustors. A research combustor was developed for exploring the dry low emissions capability of nozzles to operate in low O2 environment. A series of experiments have been conducted at representative gas turbine pressures and temperatures, in an EGR test rig. Exhaust gas generated in a first stage, at pressure, is used to vitiate the fresh air to levels determined by cycle models. Experimental results include the effect of applying EGR on operability, efficiency and emissions performance under conditions of up to 30% EGR (low oxygen). Our findings confirm the feasibility of EGR for enhanced CO2 capture, exceeding the expectations of operability and combustion efficiency predicted by models. In addition, we confirm benefits of NOx reduction while complying with CO emissions in Dry Low NOx Emissions combustors under low oxygen content oxidizer.

Overcurrent Simulation Test for High-Temperature Superconducting Generator

A small high-temperature superconductor (HTS) coil was designed and tested at the General Electric Global Research Center to evaluate the overcurrent capability for the HTS generator rotor. The superconducting rotor coil is a layer-wound racetrack coil using the BSCCO 2223 conductor. Overcurrent simulation tests have been done to simulate the fault operation condition for the generator based on previous analysis work. The obtained data are used to evaluate the performance of the HTS material in generator applications.

An investigation into feasibility of impingement heat transfer and acoustic abatement of meso scale synthetic jets

While synthetic jets have found more applications in controlling fluid flow especially in aerospace applications, more recently they captured a lot of attention for the thermal management of electronics. While the jet sizes vary and may be large for microfluidic applications, it is preferred that they should be in the meso scale range for removing heat from electronics components. Current study focuses on the heat transfer and acoustic aspects of the small-scale synthetic jets. Synthetic jets designed and developed at the General Electric Global Research Center can provide peak air velocities in excess of 90 m/s from a 1 mm hydraulic diameter rectangular orifice. The jets are driven by a sine wave with an operating frequency of between 3 and 4.5 kHz, providing the highest thermal performance for the current jets. An infrared thermal imaging technique was used to acquire fine scale temperature measurements. Two heater sizes have been studied in the current study to understand the effect of the characteristic length. Several parameters are varied to find the change in the heat transfer rates with the jet location, driving voltage, driving frequency, and heater power. Heat transfer enhancements over the specific heater sizes are presented for the same jet. It is found that the enhancement can be between 4 and 10 times depends on the heater size showing that smaller sizes provide the best jet effectiveness. It is also noted that jet noise can be as large at 73 dB, but possible abatement techniques can decrease this noise level as low as to 30 dB.

Design and performance characteristics of a digital flat-panel computed tomography system

Computed tomography (CT) applications continue to expand, and they require faster data acquisition speeds and improved spatial resolution. Achieving isotropic resolution, by means of cubic voxels, in combination with longitudinal coverage beyond 20 mm would represent a substantial advance in clinical CT because few commercially available scanners are capable of this at present. To achieve this goal, a prototype CT system incorporating a movable array of 20 cm X 20 cm, 200-microm-pitch amorphous silicon flat-panel x-ray detectors and a conventional CT x-ray source was constructed at the General Electric Global Research Center and performance tested at The University of Texas M. D. Anderson Cancer Center. The device was designed for preclinical imaging applications and has a scan field of 13 to 33 cm, with a magnification of 1.5. Image quality performance measurements, such as spatial and contrast resolutions, were obtained using both industry standard and custom phantoms. Spatial resolution, quantified by the system's modulation transfer function, indicated improvement by a factor of 2.5 to 5 in isotropic spatial resolution over current commercially available systems, with 10% modulation transfer function modulations at frequencies from 19 to 31 lp/cm. Low-contrast detectability results were obtained from industry-standard phantoms and were comprised of embedded contrast regions of 0.3%, 0.5%, and 1.0% over areas of several mm2. Performance was sufficient to easily distinguish 1.0% contrast regions down to 2 mm in diameter relative to the background. On the basis of scans of specialized hydroxyapatite phantoms, the system response is extremely linear (R2=0.990) in bone-equivalent density regimens. Standard CT dose index CTDI100 and CTDIw measurements were also conducted to assess dose delivery using a 16-cm-CTDI phantom and a 120 kV 120 mAs scan technique. The CTDIw ranged from 30 mGy (one-panel mode) to 113 mGy (two-panel mode) for this system. Lastly, several in vivo canine and murine samples were examined, and preliminary results from these scans are presented. On the basis of our results, it is clear that flat-panel-based CT scanners are useful for high-contrast high-resolution clinical applications, providing up to a 20-fold increase in volumetric resolution over most commercially available scanners.