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At least 217 records · Page 12

Harnessing Machine Learning and Data Fusion for Accurate Undocumented Well Identification in Satellite Images

This study utilizes satellite data to detect undocumented oil and gas wells, which pose significant environmental concerns, including greenhouse gas emissions. Three key findings emerge from the study. Firstly, the problem of imbalanced data is addressed by recommending oversampling techniques like Rotation–GaussianBlur–Solarization data augmentation (RGS), the Synthetic Minority Over-Sampling Technique (SMOTE), or ADASYN (an extension of SMOTE) over undersampling techniques. The performance of borderline SMOTE is less effective than that of the rest of the oversampling techniques, as its performance relies heavily on the quality and distribution of data near the decision boundary. Secondly, incorporating pre-trained models trained on large-scale datasets enhances the models’ generalization ability, with models trained on one county’s dataset demonstrating high overall accuracy, recall, and F1 scores that can be extended to other areas. This transferability of models allows for wider application. Lastly, including persistent homology (PH) as an additional input improves performance for in-distribution testing but may affect the model’s generalization for out-of-distribution testing. A careful consideration of PH’s impact on overall performance and generalizability is recommended. Overall, this study provides a robust approach to identifying undocumented oil and gas wells, contributing to the acceleration of a net-zero economy and supporting environmental sustainability efforts.

SMOTE↗

DME-to-Propane Mixture Effects on a Light Duty Compression Ignition Engine

Fuels that can be produced in a sustainable manner are of high interest because they can provide an essential step toward net zero emissions vehicles. This study examines the combustion of two such fuels, Dimethyl Ether (DME) and propane, in a compression ignition, 4-cylinder, 2.2L engine running with mixtures of DME-to-Propane ranging of 100%-0%, 85%-15%, 75%-25%, and 65%-35% by weight. Testing was conducted at 2000rpm - 100Nm, an important representative point in the FTP certification cycle. For each fuel mixture, conditions tested include sweeps of boost, EGR and injection pressure. Here, tests are mainly conducted at a constant combustion timing with CA10 of -1 deg with respect to TDC, with an engine controller combustion feedback system based on in-cylinder sampling of pressure. Trends of NOx, HC, and CO are similar for the range of DME-to-propane, from 100%-0% to 75%-25%. Boost and injection pressures had the most notable impact on the heat release traces. Higher boost, from stoichiometric to lean resulted in approximately a 3-5% increase on cycle efficiency. Fuel injection pressures resulted in about 1% gain per 200bar. Results also illustrated that EGR is effective in reducing NOx but causes notable degradation of cycle efficiency. The emissions for DME-propane mixtures with 65%-35% had a different trend, with CO and HC exceeding the runs with lower propane content by 2 to 3-fold. As propane content increases, the pressure rise rates become higher, and with 65%-35% mixtures, rates easily exceed 12bar/deg. The increased rise rates correlate with early injection timings but the rates can be reduced, with higher boost and lower injection pressures. The result of the approach, however, leads to lower thermal efficiencies, decreasing efficiency by over 5% between neat DME and the highest propane ratios.

Combustion and combustion processes↗

Fleet-Level Energy and Emissions Analysis of the US Off-Road Sector with VISION: Off-Road

In the United States (US), the off-road sector (i.e., agriculture, construction, etc.) contributes to approximately 10% of the country’s transportation greenhouse gas (GHG) emissions, similar to the aviation sector. The off-road sector is extremely diverse; as the EPA MOVES model classifies it into 11 sub-sectors, which include 85 different types of equipment. These equipment types have horsepower ranging from 1 to greater than 3000 and have very different utilization, which makes decarbonization a complex endeavor. To address this, Argonne’s on-road vehicle fleet model, VISION, has been expanded to the off-road sector. The GHG emission factors for several energy carriers (biofuels, electricity, and hydrogen) have been incorporated from Argonne’s GREET model for a sector-wide well-to-wheel (WTW) GHG emissions analysis of the present and future fleet. Several technology adoption and energy decarbonization scenarios were modeled to better understand the appropriate actions required to drive towards net-zero emissions of the off-road sector. Results show that WTW decarbonization up to 67% can be achieved from 2023 to 2050 in a business-as-usual scenario. But with aggressive sales increases of electric and hydrogen powertrains, WTW decarbonization up to 77% can be achieved, which can further increase to 85% if electricity production is aggressively decarbonized by 2035.

lifecycle↗

The diurnal variation of atomic hydrogen.

Examination of the relative importance of several effects which influence the diurnal variation of atomic hydrogen abundance near the critical level. It is pointed out that the neglect of exospheric hydrogen in a recent theoretical treatment causes an overestimation of the diurnal variation at high exospheric temperatures, and an underestimation at low exospheric temperatures. The fluxes due to lateral flow are large compared to other fluxes only to the extent that the actual diurnal variation is very different from the diurnal variation corresponding to zero net lateral flow, which does not seem to be the case in the real atmosphere. Two effects which are probably important are charge exchange reactions with thermal oxygen ions, resulting in a diurnal exchange with the plasmasphere; and charge exchange reactions with high velocity protons, resulting in enhanced escape and diurnal variation.

Tinsley, B. A.↗

Diurnal variations of atomic hydrogen - Observations and calculations

Theoretical calculations of the diurnal variation of atomic hydrogen in the thermosphere are presented that simultaneously evaluate the effects of thermosphere rotation, thermal escape, charge exchange with O(+) ions, charge exchange with hot H(+) ions, transport due to winds, and ballistic fluxes in a consistent manner. The first five effects cause a significant departure from the zero net ballistic flux condition. A thermospheric wind with a peak velocity of 50 m per sec at exobase altitude and a total charge exchange flux varying from 0 to 0.2 billion per sq cm per sec are found to be consistent with the observations.

Tinsley, B. A.↗

Baryon symmetric big bang cosmology

Both the quantum theory and Einsteins theory of special relativity lead to the supposition that matter and antimatter were produced in equal quantities during the big bang. It is noted that local matter/antimatter asymmetries may be reconciled with universal symmetry by assuming (1) a slight imbalance of matter over antimatter in the early universe, annihilation, and a subsequent remainder of matter; (2) localized regions of excess for one or the other type of matter as an initial condition; and (3) an extremely dense, high temperature state with zero net baryon number; i.e., matter/antimatter symmetry. Attention is given to the third assumption, which is the simplest and the most in keeping with current knowledge of the cosmos, especially as pertains the universality of 3 K background radiation. Mechanisms of galaxy formation are discussed, whereby matter and antimatter might have collided and annihilated each other, or have coexisted (and continue to coexist) at vast distances. It is pointed out that baryon symmetric big bang cosmology could probably be proved if an antinucleus could be detected in cosmic radiation.

Stecker, F. W.↗

Numerical modeling of diffusive physical vapor transport in cylindrical ampoules

Diffusion limited physical vapor transport in closed cylindrical ampoules of aspect ratio (length/radius) between 0.5 and 10 was studied numerically. The transport of a crystal forming component A through an inert component B, which undergoes zero net transport, was considered. A case in which the partial pressure of B is comparable to that of A, as well as systems with very low partial pressures of B (impurity cases) were treated. Concentrations and velocity distributions were obtained from the coupled transport equations for momentum, mass and components. It was found that the interdiffusion of components in viscous interaction with the container walls leads to (1) recirculation of component B, even in the absence of gravity; (2) concentration gradients normal to the main transport direction in the vapor space; and (3) non-uniform interfacial concentration gradients and, hence, non-uniform crystal growth rates.

Greenwell, D. W.↗

Numerical modeling of diffusive-convective physical vapor transport in cylindrical vertical ampoules

Diffusive-convective physical vapor transport (PVT) in cylindrical, vertical ampoules of aspect ratio (length/radius) between 0.5 and 10 was modeled numerically. The transport of a crystal forming component through an inert component that undergoes zero net transport was considered. Systems were treated in which: (1) with unequal molecular weight of the components and with temperature gradients typically employed in PVT, convective flow arises dominantly from solutal density gradients; and (2) with equal molecular weight of the components, convective flow can arise only from thermal expansion. It was found that, due to the diffusion-induced horizontal density gradients, buoyancy-driven convective flows are superimposed on the diffusive-advective fluxes without threshold. Net recirculation sets in adjacent to the growing interface, in contrast to the corresponding monocomponent situation where marginally stable convective modes fill the whole fluid space. Depending on the orientation of the main transport direction with respect to gravity, convection can either reduce or enhance the diffusion-induced radial concentration gradients. Significant enhancement of the net transport rate was found to occur only when the whole vapor space between source and growing crystal is filled by a convective recirculation roll. Solutal and thermal convection results are similar; yet for quantitative discussions, thermal and solutal Rayleigh numbers are not interchangeable in contrast to convective situations that lack net mass transport across the fluid space.

Markham, B. L.↗

Acoustic pressures emanating from a turbomachine stage

A knowledge of the acoustic energy emission of each blade row of a turbomachine is useful for estimating the overall noise level of the machine and for determining its discrete frequency noise content. Because of the close spacing between the rotor and stator of a compressor stage, the strong aerodynamic interactions between them have to be included in obtaining the resultant flow field. A three dimensional theory for determining the discrete frequency noise content of an axial compressor consisting of a rotor and a stator each with a finite number of blades are outlined. The lifting surface theory and the linearized equation of an ideal, nonsteady compressible fluid motion are used for thin blades of arbitrary cross section. The combined pressure field at a point of the fluid is constructed by linear addition of the rotor and stator solutions together with an interference factor obtained by matching them for net zero vorticity behind the stage.

Ramachandra, S. M.↗

Acoustic pressures emanating from a turbomachine stage

A knowledge of the acoustic energy emission of each blade row of a turbomachine is useful for estimating the overall noise level of the machine and for determining its discrete frequency noise content. Because of the close spacing between the rotor and stator of a compressor stage, the strong aerodynamic interactions between them have to be included in obtaining the resultant flow field. This paper outlines a three-dimensional theory for determining the discrete frequency noise content of an axial compressor consisting of a rotor and a stator each with a finite number of blades. The lifting surface theory and the linearized equation of an ideal, nonsteady compressible fluid motion are used for thin blades of arbitrary cross section. The combined pressure field at a point of the fluid is constructed by linear addition of the rotor and stator solutions together with an interference factor obtained by matching them for net zero vorticity behind the stage.

Ramachandra, S. M.↗

The non-Newtonian heat and mass transport of He 2 in porous media used for vapor-liquid phase separation

This investigation of vapor-liquid phase separation (VLPS) of He 2 is related to long-term storage of cryogenic liquid. The VLPS system utilizes porous plugs in order to generate thermomechanical (thermo-osmotic) force which in turn prevents liquid from flowing out of the cryo-vessel (e.g., Infrared Astronomical Satellite). An apparatus was built and VLPS data were collected for a 2 and a 10 micrometer sintered stainless steel plug and a 5 to 15 micrometer sintered bronze plug. The VLPS data obtained at high temperature were in the nonlinear turbulent regime. At low temperature, the Stokes regime was approached. A turbulent flow model was developed, which provides a phenomenological description of the VLPS data. According to the model, most of the phase separation data are in the turbulent regime. The model is based on concepts of the Gorter-Mellink transport involving the mutual friction known from the zero net mass flow (ZNMF) studies. The latter had to be modified to obtain agreement with the present experimental VLPS evidence. In contrast to the well-known ZNMF mode, the VLPS results require a geometry dependent constant (Gorter-Mellink constant). A theoretical interpretation of the phenomenological equation for the VLPS data obtained, is based on modelling of the dynamics of quantized vortices proposed by Vinen. In extending Vinen's model to the VLPS transport of He 2 in porous media, a correlation between the K*(GM) and K(p) was obtained which permits an interpretation of the present findings. As K(p) is crucial, various methods were introduced to measure the permeability of the porous media at low temperatures. Good agreement was found between the room temperature and the low temperature K(p)-value of the plugs.

Yuan, S. W. K.↗

Methods for computing comet core temperatures

The temperature profile within the comet nucleus provides the key to an understanding of the history of the volatiles within a comet. Certain difficulties arise in connection with current cometary temperature models. It is shown that the constraint of zero net heat flow can be used to derive general analytical expressions which will allow for the determination of comet core temperature for a spherically symmetric comet, taking into account information about the surface temperature and the thermal conductivity. The obtained results are compared with the expression for comet core temperatures considered by Klinger (1981). Attention is given to analytical results, an example case, and numerical models. The formalization developed makes it possible to determine the core temperature on the basis of the numerical models of the surface temperature.

Mckay, C. P.↗

Theoretical approach to obtaining dynamic characteristics of noncontacting spiral-grooved seals

The dynamic characteristics of spiral-grooved seals are theoretically obtained by using the Navier-Stokes equation. First, with the inertia term of the fluid considered, the flow and pressure in the steady state are obtained for the directions parallel to and perpendicular to the groove. Next, the dynamic character is obtained by analyzing the steady state and by analyzing the labyrinth seal. As a result, the following conclusions were drawn: (1) As the land width becomes shorter or the helix angle decreases, the cross-coupling stiffness, direct and cross-coupling damping, and add mass coefficients decrease; (2) As the axial Reynolds number increases, the stiffness and damping coefficients increase. But the add mass coefficient is not influenced by the axial Reynolds number; (3) The rotational Reynolds number influences greatly the direct and cross-coupling stiffness and direct damping coefficients; and (4) As the journal rotating frequency increases, the leakage flow decreases. Therefore zero net leakage flow is possible at a particular rotating frequency.

Iwatsubo, Takuzo↗

Utilization of FEP energetics

The research and development work on Fountain Effect Pump Systems (FEP systems) has been of interest in the competition between mechanical pumps for He II and FEP units. The latter do not have moving parts. In the course of the work, the energetics have been addressed using one part of a simple four-changes-of-state cycle. One option is the FEP ideal change of state at constant chemical potential (mu). The other option is the two-state sequence mu-P with a d mu=0 state change followed by an isobar. Questions of pump behavior, of flow rate response to temperature difference at the hot end, and related questions of thermodynamic cycle completion and heat transfer have been addressed. Porous media data obtained elucidate differences between vapor-liquid phase separation (VLPS) and Zero Net Mass Transfer (ZNMF).

Frederking, T. H. K.↗

Space cryogenics components based on the thermomechanical (TM) effect

He II vapor-liquid phase separation (VLPS) is discussed, with emphasis on fluid-related transport phenomena. The VLPS system has been studied for both linear and nonlinear regimes, demonstrating that well-defined convection patterns exist in porous plug phase separators. In the second part, other components based on the thermomechanical effect are discussed in the limit of ideal conditions. Examples considered include the heat pipe transfer of zero net mass flow, liquid transfer pumps based on the fountain effect, mechanocaloric devices for cooling purposes, and He II vortex refrigerators.

Yuan, S. W. K.↗

Turbulent transport of He II in active and passive phase separators using slit devices and porous media

The turbulent transport mode of vapor liquid phase separators (VLPS) for He II has been investigated comparing passive porous plug separators with active phase separators (APS) using slits of variable flow paths within a common frame of reference. It is concluded that the basic transport regimes in both devices are identical. An integrated Gorter-Mellink (1949) equation, found previously to predict VLPS results of porous plugs, is employed to analyze APS data published in the literature. It is found that the Gorter-Mellink flow rate parameter for 9-micron and 14-micron APS slit widths are relatively independent of the slit width, having a rate constant of about 9 + or - 10 percent. This agrees with the early heat flow results for He II entropy transport at zero net mass flow in wide capillaries and slits.

Yuan, S. W. K.↗

Space structures concepts and materials

An extension is preseted of the evaluation of graphite/aluminum metal matrix composites (MMC) for space structures application. A tubular DWG graphite/aluminum truss assembly was fabricated having the structural integrity and thermal stability needed for space application. DWG is a proprietary thin ply continuous graphite reinforced aluminum composite. The truss end fittings were constructed using the discontinuous ceramic particulate reinforced MMC DWAl 20 (trademark). Thermal stability was incorporated in the truss by utilizing high stiffness, negative coefficient of thermal expansion (CTE) P100 graphite fibers in a 6061 aluminum matrix, crossplied to provide minimized CTE in the assembled truss. Tube CTE was designed to be slightly negative to offset the effects of the end fitting and sleeve, CTE values of which are approx. 1/2 that of aluminum. In the design of the truss configuration, the CTE contribution of each component was evaluated to establish the component dimension and layup configuration required to provide a net zero CTE in the subassemblies which would then translate to a zero CTE for the entire truss bay produced.

Nowitzky, A. M.↗