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"Measurement Experiments."
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How high is high? : science projects with height and depth
\"Simple science experiments about measurement of height and depth using everyday items with many experiments that can be turned into science fair projects.\"-- Provided by publisher.
Book
Investigation of Temperature Variations and Extreme Temperature Differences for the Corrugated Web Steel Beams under Solar Radiation
Due to the coupling impacts of solar radiation, wind, air temperature and other environmental parameters, the temperature field of steel structures is significantly non-uniform during their construction and service stages. Corrugated web steel beams have gained popularity in structural engineering during the last few decades, while their thermal actions are barely investigated. In this paper, both experimental and numerical investigations were conducted to reveal the non-uniform features and time variation of the corrugated web steel beams under various environmental conditions. The heat-transfer simulation model was established and verified using the experimental temperature data. Both the experiment and simulation results demonstrate that the steel beam has a complicated and non-uniform temperature field. Moreover, 2-year continuous numerical simulations of steel beams’ thermal actions regarding eight different cities were carried out to investigate the long-term temperature variations. Finally, based on the long-term simulation results and extreme value analysis (EVA), the representative values of steel beams’ daily temperature difference with a 50-year return period were determined. The extreme temperature difference of the steel beam in Harbin reached up to 46.9 °C, while the extreme temperature difference in Haikou was 28.8 °C. The extreme temperature difference is highly associated with the steel beam’s location and surrounding climate. Ideally, the outcomes will provide some contributions for the structural design regarding the corrugated web steel beam.
Journal Article
How heavy is heavy? : science projects with weight
\"Simple science experiments about measurement of weight using everyday items with many experiments that can be turned into science fair projects.\"-- Provided by publisher.
Book
How to conduct variable-density sand tank experiments: practical hints and tips
Sand tank experiments are a powerful tool for the investigation and visualization of groundwater flow dynamics. Especially when studying coastal aquifers, where the presence of both fresh and saline water induces complex variable-density flow and transport processes, the controlled laboratory settings of tank experiments help scientists to identify general patterns and features. This technical note provides practical information on planning, conducting and evaluating sand tank experiments, with a focus on application to coastal hydrogeology. Materials, e.g. the sand tank itself, liquids and porous media, are discussed, as well as their handling and auxiliary equipment. The collation of hints and tips is intended to guide novices, as well as experienced researchers, and possibly prevent them from repeating the errors that have been encountered during a long history of experimental work conducted by the authors and researchers associated with many other published studies.
Journal Article
Review: Pre-Darcy flows in low-permeability porous media
The widely used Darcy’s law specifies a linear relation between the Darcy velocity of fluid flow and the pressure gradient that drives the flow. However, studies have shown that Darcy velocity can exhibit a nonlinear dependence on the pressure gradient in low-permeability porous media such as clay and shale when the pressure gradient is adequately low. This phenomenon is referred to as low-velocity non-Darcian flow or pre-Darcy flow. This paper provides a comprehensive review of the theories, experimental data, and modeling methods for pre-Darcy flow in low-permeability porous media. The review begins by outlining the fundamental mechanisms underlying pre-Darcy flow that regulate the unique characteristics such as nonlinear dependence of the Darcy velocity on the pressure gradient and its relevance to fluid–rock interactions. The review then proceeds to present a thorough compilation of experimental investigations performed in various low-permeability geomaterials including tight sandstones, shales, and clays. Next, empirical and theoretical models and simulation methods that have been developed to fit and interpret experimental data are reviewed. Finally, the review underscores the challenges encountered in conducting and interpreting pre-Darcy flow experiments and suggests future research directions. By analyzing previous experimental investigations, this review aims to offer a valuable resource for researchers and practitioners seeking to enhance their understanding of fluid dynamics in low-permeability geomaterials. This provides insights into the application of pre-Darcy flow in numerous natural and engineered processes such as shale oil and gas recovery, contaminant transport in low-permeability aquifers, and geological disposal of nuclear waste.
Journal Article
HydrogeoSieveXL: an Excel-based tool to estimate hydraulic conductivity from grain-size analysis
For over a century, hydrogeologists have estimated hydraulic conductivity (
K
) from grain-size distribution curves. The benefits of the practice are simplicity, cost, and a means of identifying spatial variations in
K
. Many techniques have been developed over the years, but all suffer from similar shortcomings: no accounting of heterogeneity within samples (i.e., aquifer structure is lost), loss of grain packing characteristics, and failure to account for the effects of overburden pressure on
K
. In addition,
K
estimates can vary by an order of magnitude between the various methods, and it is not generally possible to identify the best method for a given sample. The drawbacks are serious, but the advantages have seen the use of grain-size distribution curves for
K
estimation continue, often using a single selected method to estimate
K
in a given project. In most cases, this restriction results from convenience. It is proposed here that extending the analysis to include several methods would be beneficial since it would provide a better indication of the range of
K
that might apply. To overcome the convenience limitation, an Excel-based spreadsheet program, HydrogeoSieveXL, is introduced here. HydrogeoSieveXL is a freely available program that calculates
K
from grain-size distribution curves using 15 different methods. HydrogeoSieveXL was found to calculate
K
values essentially identical to those reported in the literature, using the published grain-size distribution curves.
Journal Article
Vibration control of a marine centrifugal pump using floating raft isolation system
In order to study the influence of floating raft isolation system (FRIS) on the vibration characteristics of marine pump, a marine centrifugal pump with/without FRIS under the same operation condition, which specific speed is 66.7, was experimentally measured. The maximum efficiency of the pump is 75.8%, which is under 1.2Qd. Results show that the characteristic frequencies in the vibration spectrums of the pump with/without FRIS are APF (axial passing frequency), the BPF (blade passing frequency) and its high-order harmonic frequency. After installing FRIS, under 0.8Qd, 1.0Qd and 1.2Qd, the vibration intensity of the pump at inlet flange is slighter than that at pump base and larger than that at pump bracket. The vibration intensity at outlet flange is slighter than that at the pump bracket and larger than that at pump body, and the vibration intensity at connecting plate is the lowest. The vibration velocity level of pump base decreases with the increase of flow rate, the maximum vibration intensity at M1–M4 is reduced by 88% than that without FRIS, and the maximum vibration velocity of the APF at M1–M4 is reduced by 83.3% than that without FRIS.
Journal Article
Experimental study of water and salt migration in unsaturated loess
Water and salt migration properties are important in many disciplines, including engineering construction, natural disaster prevention, agricultural irrigation and wastewater disposal. Relevant research into unsaturated loess caters to the development needs of the cities located on it. The objective of this study is to identify the water flow dynamics and consequent salt migration and redistribution (as well as their influence on microstructure alteration of the soil) during long-term seepage in unsaturated loess. In this experimental study, a long-term and one-dimensional seepage simulation test is conducted in a loess column. Probes are buried at different depths along the vertical profile to monitor and record the variations of volume water content and electrical conductivity. After the seepage test, soils at different depths are analyzed with different methods to make further investigation, including use of a pressure-plate apparatus to obtain soil-water characteristic curves, ion chromatography to determine the soluble salt components, and scanning electron microscopy to observe the microstructure changes. Good consistency between the different tests is obtained. Based on those results, the water and salt migration patterns and their influence on loess are analyzed and concluded.
Journal Article
Experimental observations of aquifer storage and recovery in brackish aquifers using multiple partially penetrating wells
Aquifer storage and recovery systems using multiple partially penetrating wells (MPPW-ASR) can form a viable solution to the problem of freshwater buoyancy when using brackish aquifers for freshwater storage. This study presents the result of a series of laboratory experiments that aimed at visualizing the shape of freshwater bodies injected into a brackish aquifer and determining the effect on the recovery efficiency (RE) of several MPPW-ASR operational variables. A model aquifer was built in a Plexiglas tank using glass beads and water was injected and abstracted through point and vertical wells, which were operated in various combinations. Numerical models were used to support the interpretation of the time-lapse photographs, and showed that three-dimensional flow effects had to be considered for a correct interpretation of the visible dye patterns. Upward migration of both fresh (during injection) and brackish water (during recovery) along the vertical wells was observed, indicating that the role of well infrastructure as conduits is a critical design criterion for real-world systems. Gravitational instabilities formed when freshwater did not extend all the way to the top of the aquifer, and this negatively impacted the RE by causing greater mixing. The positive freshwater buoyancy led to freshwater bodies that became narrower with depth, and the formation of thin, elongated buffer zones along the aquifer top in multicycle experiments. Up-coning below abstraction wells resulted in lower RE values, reinforcing the potential of scavenger wells to enhance MPPW-ASR system performance.
Journal Article
Impact of angle patterns at fracture intersections on nonlinear flow behavior and local flow field: a visualization experiment
The influence of angle patterns of intersecting fractures is crucial for a profound understanding of the flow characteristic of fractured rock masses. This study employs hydraulic and visualization experiments to investigate macroscopic nonlinear flow behavior and local flow field characteristics of a “one inlet two outlet” fracture intersection with varying angle patterns. The angle pattern exerts a significant influence on the morphology of the intersection, leading to enhanced nonlinear flow and altered flow rate distribution. Both the nonlinear coefficient (b) and the ratio of flow rate distribution (ɛ) exhibit a Gaussian distribution pattern with respect to the angle patterns. By observing the intersection morphology and local flow fields under different angle patterns, it was found that the protrusion caused by the inlet and outlet fractures significantly impacts the fluid flow entering the outlet fractures, particularly under high Reynolds number (Re) conditions. Using a machine learning algorithm based on neural networks, the flow rate distribution at the outlet of the intersection fracture under different Re values and angle patterns is predicted. The model demonstrated accurate predictions of the outlet flow rate distribution for intersection fractures under diverse conditions. Additionally, by analyzing the flow velocity and flow characteristics at different positions within the intersection, the relationship between the macroscopic flow rate distribution and the flow field characteristics at the intersection has been clarified. These results will aid in the study of groundwater flow behavior, fluid flow in microfluidic chips, and seepage heat transfer.
Journal Article