A two-stage traveling-wave thermoacoustic electric generator with loudspeakers as alternators

This paper presents the design, construction and tests of a traveling-wave thermoacoustic electric generator. A two-stage travelling-wave thermoacoustic engine converts thermal energy to acoustic power. Two low-impedance linear alternators (i.e., audio loudspeakers) were installed to extract and convert the engine’s acoustic power to electricity. The coupling mechanism between the thermoacoustic engine and alternators has been systematically studied numerically and experimentally, hence the optimal locations for installing the linear alternators were identified to maximize the electric power output and/or the thermal-to-electric conversion efficiency. A ball valve was used in the loop to partly correct the acoustic field that was altered by manufacturing errors. A prototype was built based on this new concept, which used pressurized helium at 1.8 MPa as the working gas and operated at a frequency of about 171 Hz. In the experiment, a maximum electric power of 204 W when the hot end temperature of the two regenerators reaches 512℃ and 452℃, respectively. A maximum thermal-to-electric efficiency of 3.43% was achieved when the hot end temperature of the two regenerators reaches 597℃ and 511℃, respectively. The research results presented in this paper demonstrate that multi-stage travelling-wave thermoacoustic electricity generator has a great potential for developing inexpensive electric generators

Estimated ultimate recovery prediction of fractured horizontal wells in tight oil reservoirs based on deep neural networks

Accurate estimated ultimate recovery prediction of fractured horizontal wells in tight reservoirs is crucial to economic evaluation and oil field development plan formulation. Advances in artificial intelligence and big data have provided a new tool for rapid production prediction of unconventional reservoirs. In this study, the estimated ultimate recovery prediction model based on deep neural networks was established using the data of 58 horizontal wells in Mahu tight oil reservoirs. First, the estimated ultimate recovery of oil wells was calculated based on the stretched exponential production decline model and a five-region flow model. Then, the calculated estimated ultimate recovery, geological attributes, engineering parameters, and production data of each well were used to build a machine learning database. Before the model training, the number of input parameters was reduced from 14 to 9 by feature selection. The prediction accuracy of the model was improved by data normalization, the early stopping technique, and 10-fold cross validation. The optimal activation function, hidden layers, number of neurons in each layer, and learning rate of the deep neural network model were obtained through hyperparameter optimization. The average determination coefficient on the testing set was 0.73. The results indicate that compared with the traditional estimated ultimate recovery prediction methods, the established deep neural network model has the strengths of a simple procedure and low time consumption, and the deep neural network model can be easily updated to improve prediction accuracy when new well information is obtained.Cited as: Luo, S., Ding, C., Cheng, H., Zhang, B., Zhao, Y., Liu, L. Estimated ultimate recovery prediction of fractured horizontal wells in tight oil reservoirs based on deep neural networks. Advances in Geo-Energy Research, 2022, 6(2): 111-122. https://doi.org/10.46690/ager.2022.02.0

Modelling Ice and Wax Formation in a Pipeline in the Arctic Environment

PresentationIn the Arctic environment, fluid temperature in pipeline can drop below the freezing point of water, which causes wax and ice to form on pipeline surface. Solid formation on pipeline surface can lead to flow assurance and process safety issues, such as blockage of pipeline, pipeline component failure, and the release of hazardous liquid. The blockage of pipeline can cause additional burden or failure to pumping system. Remediating the plugging requires shutdown of pipeline operation, which cause tremendous cost and delay to the entire production system. Ice and wax deposition in pipeline is a slow process. Pigging operation can be used to remove the deposits on pipeline surface. However, if deposition is too thick, pipeline blockage can still occur. In order to prevent pipeline blockage, ice and wax deposition rates are required to be estimated. This paper investigates ice and wax deposition rates in a 90 km pipeline. A fundamental model for both ice and wax deposition is proposed using first principles of heat and mass transfer. The interaction between water and wax is analysed

Group delay dispersion monitoring for computational manufacturing of dispersive mirrors

We present a computational manufacturing program for monitoring group delay dispersion (GDD). Two kinds of dispersive mirrors computational manufactured by GDD, broadband, and time monitoring simulator are compared. The results revealed the particular advantages of GDD monitoring in dispersive mirror deposition simulations. The self-compensation effect of GDD monitoring is discussed. GDD monitoring can improve the precision of layer termination techniques, it may become a possible approach to manufacture other optical coatings

Toward Low‐Temperature Zinc‐Ion Batteries: Strategy, Progress, and Prospect in Vanadium‐Based Cathodes

Low-temperature vanadium-based zinc ion batteries (LT-VZIBs) have attracted much attention in recent years due to their excellent theoretical specific capacities, low cost, and electrochemical structural stability. However, low working temperature surrounding often results in retarded ion transport not only in the frozen aqueous electrolyte, but also at/across the cathode/electrolyte interface and inside cathode interior, significantly limiting the performance of LT-VZIBs for practical applications. In this review, a variety of strategies to solve these issues, mainly including cathode interface/bulk structure engineering and electrolyte optimizations, are categorially discussed and systematically summarized from the design principles to in-depth characterizations and mechanisms. In the end, several issues about future research directions and advancements in characterization tools are prospected, aiming to facilitate the scientific and commercial development of LT-VZIBs

Encapsulating lithium and sodium inside amorphous carbon nanotubes through gold-seeded growth

Abstract(#br)Metallic lithium promises the ultimate anode material for building next-generation Li batteries, though some fundamental hurdles remain unsolved. Li growth induced by hetero particles/atoms has recently emerged as a highly efficient route enabling spatial-control and dendrite-free Li deposition on anode hosts. However, the detailed mechanism of Li nucleation and its interaction with heterogeneous seeds are largely unknown. Herein, we investigate this issue by visualizing Au-seeded Li nucleation processes that guide Li deposition inside the one-dimensional hollow space of individual amorphous carbon nanotubes by in-situ transmission electron microscopy. A reversible two-step conversion process during Au–Li alloying/dealloying reactions is revealed, suggesting that the formation of Li 3 Au plays the actual role in inducing Li nucleation. We propose a front-growth scenario to explain the spatially confined Li growth and stripping kinetic behaviors, which involves the mass addition and removal at the deposition front through ion diffusion along the tubular carbon shell. As a comparison, nanotubes without gold seeds inside exhibit uncontrolled dendrite-like Li growth outside the carbon shell. We further demonstrate that Au-seed growth can be successful in encapsulating sodium metal for the first time. These findings provide mechanistic insights into heterogeneous seeded Li/Na nucleation and space-confined deposition for design of high-performance battery anodes

A novel internal fixation technique for the treatment of olecranon avulsion fracture

ObjectiveTension band wiring and proximal ulnar plate fixation are commonly used fixation methods for olecranon fractures. However, they may not be suitable for repairing proximal olecranon avulsion fractures. In this study, we present a novel fixation technique for the treatment of proximal avulsion fractures, which is a T-shaped plate combined with a wire.Materials and methodsBetween March 2016 and May 2020, surgery was performed on 16 patients with proximal olecranon avulsion fractures by using a T-shaped plate combined with a wire fixation at our hospital. The parameters followed were fracture healing time, elbow range of motion (ROM), related functional scores (the Mayo score and the DASH score), and complications related to internal fixation.ResultsThe average follow-up period was 17 (14–21) months and fractures had healed in all patients included in the study, with an average fracture union of 9.25 (8–12) weeks. No patient reported fixation failure, serious infection, or revision surgery. The average ROM of the elbow joint was 123° (120–135°). The Mayo score was excellent in 11 patients and good in 5. The average DASH score was 17.75 (12–24).ConclusionOlecranon avulsion fractures were fixed with a T-shaped steel plate combined with a steel wire, which can be used for early functional exercise and for achieving good final functional results. This method can provide stable fixation, especially in elderly patients with osteoporosis

Investigations on the micellization of amphiphilic dendritic copolymers: from unimers to micelles

Since the micellization kinetics is influenced by polymer structure, the spherical three-dimensional topology of amphiphilic dendritic copolymers (ADPs) which hinders the phase separation during micellization is assumed to make the micellization kinetics different. In the literatures, most of the attention has been paid to the morphology transition or the morphology at equilibrium and the micellization kinetics of ADPs is rarely reported. In this study, the micellization processes of amphiphilic dendritic copolymers from unimers to the final equilibrium micelles were monitored by laser light scattering. Based on the closed association mechanism, the thermodynamics of micellization was analysed. The negative thermodynamic quantities indicate that the micellization of ADPs is driven by enthalpy. Based on the change of scattering intensity and hydrodynamic radius (Rh) with time, the detailed micellization kinetics was analysed, which contains two steps. By controlling the temperature and type of solvent, a system in which the concentration has little influence on Rh is obtained. The relaxation times of the two steps decrease with concentration, indicating that at higher concentration the rate of micellization is quicker. With the increasing mass fraction of the hydrophobic part, the relaxation times decrease and the driving force of micellization increases