Simulation of the effect of stand-off parameter on collapse behaviours of a single cavitation bubble in jet drilling

Cavitation jet drilling has been extensively employed for the exploitation of geo-energy resources. The dynamics of cavitation bubbles in close proximity to the solid boundary have been a subject of great interest during jet drilling, as they play a crucial role in determining the cavitation performance. In present work, the dynamics of a single cavitation bubble near a solid surface is numerically investigated by using the axisymmetric Navier-Stokes equations and the volume of fluid method with considering the surface tension of gas-liquid interface, liquid viscosity and compressibility of gas in bubble. The simulated profiles are qualitatively and quantitatively consistent with the experimental images, which proves the reliability of employed numerical model. The effects of stand-off distance on the bubble profiles, bubble volume and collapse time have been analysed. Moreover, the cavitation erosion patterns towards the solid wall are also revealed for different dimensionless standoff distances. The simulation results reveal two distinct collapse patterns for the bubble profiles. The solid wall significantly impedes the shrinkage rate of the bubble, resulting in the longest collapse time when the dimensionless stand-off distance is 1.0. Three erosion patterns of cavitation bubbles towards the solid wall are observed, with the shock wave and micro-jet both contributing significantly to the damage caused by cavitation erosion. The shock wave sweeps the wall resulting in circular corrosion pits with a severely eroded centre, while the micro jet penetrates the wall leading to small spot corrosion pits.Document Type: Original articleCited as: Wu, X., Zhang, Y., Huang, H., Hui, C., Hu, Z., Li, G. Simulation of the effect of stand-off parameter on collapse behaviours of a single cavitation bubble in jet drilling. Advances in Geo-Energy Research, 2023, 8(3): 181-192. https://doi.org/10.46690/ager.2023.06.0

CMB-S4: Forecasting Constraints on Primordial Gravitational Waves

CMB-S4---the next-generation ground-based cosmic microwave background (CMB) experiment---is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the Universe, from the highest energies at the dawn of time through the growth of structure to the present day. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semi-analytic projection tool, targeted explicitly towards optimizing constraints on the tensor-to-scalar ratio, $r$, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2--3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments given a desired scientific goal. To form a closed-loop process, we couple this semi-analytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for $r > 0.003$ at greater than $5\sigma$, or, in the absence of a detection, of reaching an upper limit of $r < 0.001$ at $95\%$ CL.Comment: 24 pages, 8 figures, 9 tables, submitted to ApJ. arXiv admin note: text overlap with arXiv:1907.0447

Performance and characterization of the SPT-3G digital frequency-domain multiplexed readout system using an improved noise and crosstalk model

The third-generation South Pole Telescope camera (SPT-3G) improves upon its predecessor (SPTpol) by an order of magnitude increase in detectors on the focal plane. The technology used to read out and control these detectors, digital frequency-domain multiplexing (DfMUX), is conceptually the same as used for SPTpol, but extended to accommodate more detectors. A nearly 5× expansion in the readout operating bandwidth has enabled the use of this large focal plane, and SPT-3G performance meets the forecasting targets relevant to its science objectives. However, the electrical dynamics of the higher-bandwidth readout differ from predictions based on models of the SPTpol system due to the higher frequencies used and parasitic impedances associated with new cryogenic electronic architecture. To address this, we present an updated derivation for electrical crosstalk in higher-bandwidth DfMUX systems and identify two previously uncharacterized contributions to readout noise, which become dominant at high bias frequency. The updated crosstalk and noise models successfully describe the measured crosstalk and readout noise performance of SPT-3G. These results also suggest specific changes to warm electronics component values, wire-harness properties, and SQUID parameters, to improve the readout system for future experiments using DfMUX, such as the LiteBIRD space telescope

CMB-S4

We describe the stage 4 cosmic microwave background ground-based experiment CMB-S4

CMB-S4: Forecasting Constraints on Primordial Gravitational Waves

Abstract: CMB-S4—the next-generation ground-based cosmic microwave background (CMB) experiment—is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the universe. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semianalytic projection tool, targeted explicitly toward optimizing constraints on the tensor-to-scalar ratio, r, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2–3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments, given a desired scientific goal. To form a closed-loop process, we couple this semianalytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for r > 0.003 at greater than 5σ, or in the absence of a detection, of reaching an upper limit of r < 0.001 at 95% CL

A Programmable Real-Time Data Processor

International Telemetering Conference Proceedings / October 24-27, 1983 / Sheraton-Harbor Island Hotel and Convention Center, San Diego, CaliforniaA new type of programmable data processor for a telemetry system is described, in which the functional tables constructed by EPROM’s was employed for fast conversion of the measured binary code to easily understood data results by people, and a printer/plotter made in our country was used as Recordin device. Synchronization problems between the printer/plotter turning in high speed and the telemetry system have been solved fairly good. The data processing speed is 13200 characters per second. All of the circuit elements were mounted on a printed circuit board and we enclosed it in the case of the printer/plotter. The processor is directly linked to the synchnizer of telemetry system and the timer, and can process all the data obtainned from certain telemetry system in real-time.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

Manipulation of DNA transport through solid-state nanopores by atomic force microscopy

To realize DNA sequencing by a solid-state nanopore, the translocation speed of DNA through the nanopore should be slowed down to obtain the temporal resolution. In this study, we make a nanopore sensing system integrated with an atomic force microscope to control DNA transport through solid-state nanopores. The speed of DNA bound to the probe tip through the nanopore can be controlled by manipulating AFM probe tip, the ionic current as well as the force exerted on DNA strand while it is translocating through the nanopore could be simultaneously measured by the integrated system. The velocity of DNA molecules could be slowed down to ∼100 nm s ^−1 , much less than 1 nt ms ^−1 , which fully meets the requirement for nanopore DNA sequencing. When the probe tip is moving toward or away from the nanopore, obvious current steps associated with force steps are observed during the capturing and releasing processes of DNA strands. All-atom molecular dynamics simulation further validates the observed correlation between the ionic current and dragging force when the DNA is moving through the nanopore

Tribological Performances Of Dicationic Ionic Liquids At Elevated Temperature

Ionic liquid 1, 6-bis (3-hexylimidazolium-1yl) hexylene hexafluorophosphate was synthesized. The kinetic viscosity and mass density of the ionic liquid were determined. The tribological performance of the ionic liquid for steel/Cu-Sn alloy was evaluated on an Optimol SRV oscillating friction and wear tester under ambient conditions. Benzotriazole was used as lubricant additive in ionic liquid to inhibit tribo-corrosion from Ionic liquid 1, 6-bis (3-hexylimidazolium-1yl) hexylene hexafluorophosphate. The worn surfaces on Cu-Sn alloy disc were analyzed by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). SEM results show slight abrasion and tribo-corrosion on the worn surfaces when BTA was used. XPS results indicate boundary lubrication film was composed of Cu 2 O and CuO by the tribochemical reactions of ionic liquid with Cu-Sn alloy during the sliding process

Discussion on practice of green highway construction based on high quality objectives

Creating green roads is an objective requirement for the transformation and development of the transportation industry. It is also an objective requirement for advancing the supply-side structural reform of the transportation industry and building a satisfactory transportation for the people. It is also an objective requirement for achieving a beautiful China. The author puts forward some practical experiences of green highway construction through the construction of the typical demonstration project of the Guangji expressway green highway