Study on Load Bearing Characteristics of Novel Expandable Deepwater Drilling Conductor Based on Laboratory Experiment and Field Test

A novel expandable conductor was designed and applied in deep-water drilling to improve the vertical and lateral bearing capacity with a significant reduction of conductor jetting depth and soaking time. The vertical and lateral bearing capability of expandable conductors was depicted based on the ultimate subgrade reaction method and pile foundation bearing theory. The load-bearing characteristics of a laboratory-scale expandable conductor were analyzed through laboratory experiments. The serial simulation experiments are accomplished to study the bearing characteristics(vertical ultimate bearing capacity, lateral soil pressure, and lateral displacement) during the conductor soaking process. The laboratory experimental results show that the larger the length and thickness of expandable materials are,the higher the bearing capacity of the wellhead will be. During the conductor soaking process, the soil pressure around the three expandable conductors increases faster, strings representing a stronger squeezing effect and resulting in higher vertical bearing capacity. Furthermore, the lateral displacement of novel expandable conductor is smaller than that of the conventional conductor. All the advantages mentioned above contributed to the reduction of conductor’s jetting depth and soaking time. Lastly, the application workflow of a novel expandable deep-water drilling conductor was established and the autonomous expandable conductor was successfully applied in the South China Sea with a significant reduction of conductor’s jetting depth and soaking time. According to the soil properties and designed installation depth of the surface conductor, the arrangement of expandable materials should be designed reasonably to meet the safety condition and reduce the construction cost of the subsea wellhead.

3D Mobile Augmented Reality Interface for Laboratory Experiments

In fields such as science and engineering, virtual environment is commonly used to provide replacements for practical hands-on laboratories. Sometimes, these environments take the form of a remote interface to the physical laboratory apparatus and at other times, in the form of a complete software implementation that simulates the laboratory apparatus. In this paper, we report on the use of a semi-immersive 3D mobile Augmented Reality (mAR) interface and limited simulations as a replacement for practical hands-on laboratories in science and engineering. The 3D-mAR based interfaces implementations for three different experiments (from micro-electronics, power and communications engineering) are presented;the discovered limitations are discussed along with the results of an evaluation by science and engineering students from two different institutions and plans for future work.

Declaring income versus declaring taxes in tax compliance experiments:Does the design of laboratory experiments affect the results?

Laboratory experiments are frequently criticised,in part because of the sensitivity of the results to specific features of the design.This paper addresses an important question regarding the key aspect of the experimental environment:How should the dependent variable–participants’choices–be operationalised?For the specific context of laboratory research on income tax compliance,we compare the effects of the two most common operationalisation types:the declaration of gross income versus the declaration of tax payment.It is found that compliance is higher when participants indicate their tax payment than when they declare their income.It is also discovered that the effects of the three policy parameters of the economic model(the tax rate,audit probability and fine rate)are stronger when participants declare their taxes than when they declare their income.These results are relevant for interpreting prior and future experimental evidence on tax compliance and can explain some contradictory previous findings.More broadly,this study suggests that the results of laboratory experiments may depend on specific features of the experimental design,which proposes a strong need for more systematic methodological research.

Experimental investigation and flow analysis of clear-water scour around pier and abutment in proximity

Local scour around bridge piers and abutments is one of the most significant causes of bridge failure.Despite a plethora of studies on scour around individual bridge piers or abutments,few studies have focused on the joint impact of a pier and an abutment in proximity to one another on scour.This study conducted laboratory experiments and flow analyses to examine the interaction of piers and abutments and their effect on clear-water scour.The experiments were conducted in a rectangular laboratory flume.They included 18 main tests(with a combination of different types of piers and abutments)and five control tests(with individual piers or abutments).Three pier types(a rectangular pier with a rounded edge,a group of three cylindrical piers,and a single cylindrical pier)and two abutment types(a wingewall abutment and a semicircular abutment)were used.An acoustic Doppler velocimeter was used to measure the three-dimensional flow velocity for analyses of streamline,velocity magnitude,vertical velocity,and bed shear stress.The results showed that the velocity near the pier and abutment increased by up to 80%.The maximum scour depth around the abutment increased by up to 19%.In contrast,the maximum scour depth around the pier increased significantly by up to l71%.The presence of the pier in the vicinity of the abutment led to an increase in the scour hole volume by up to 87%relative to the case with a solitary abutment.Empirical equations were also derived to accurately estimate the maximum scour depth at the pier adjacent to the abutment.

PIV experimental study on the interactions between ice ridges and stratified fluids

With the rapid decline of Arctic sea ice,the freshwater produced by melting of summer sea ice makes the depth of the halocline under ice become shallower.This has an impact on the drift of sea ice because internal waves may be generated at the interface of the halocline by disturbance from the draft of an ice floe or ridge keel.A laboratory experimental study was carried out to investigate the interactions between an ice ridge and stratified fluid using the method of Particle Image Velocimetry(PIV).The drift velocity of an ice ridge(U) and the draft of the ridge keel(D) were altered in different experimental cases,and the velocity field in the stratified fluid was then measured by PIV.The results reveal that an obvious vortex exists in the wake field of the ridge keel,and the center of the vortex moves away from the ice ridge with increasing D.Internal waves at the interface of the stratified fluid were observed during the drift of the ice ridge,and the wave height shows a positive correlation with U and D.This study demonstrates that ice ridges could introduce internal waves at the interface of a stratified fluid and thus affect the oceanic drag coefficient and ice drift.It supports improved parameterization of the ice drag coefficients.

An Experimental Study on the Pressure Distribution in Horizontal Gas Wells

Laboratory experiments have been carried out to study the fluid flow in the wellbore of a horizontal gas well during the production process.The related pressure distribution has been determined considering different cases(different inflow media,different perforation opening methods and different liquid holdup).It has been found that the larger the fluid flow rate,the greater the pressure changes in the wellbore under the same hole opening mode.The uniformity of the perforation opening method was also an important factor affecting the magnitude of the wellbore pressure change.The liquid holdup also affected the pressure distribution,especially when the gas volumetric flow rate exceeded 200 m3/h.Comparison of the outcomes of the present experimental study with the predictions of a theoretical model available in the literature has provided a relative error smaller than 20%.

Experimental and numerical investigation of groundwater head losses on and nearby short intersections between disc-shaped fractures

Discrete fracture models are used for investigating precise processes of groundwater flow in fractured rocks,while a disc-shaped parallel-plates model for a single fracture is more reasonable and efficient for computational treatments.The flow velocity has a large spatial differentiation which is more likely to produce non-linear flow and additional head losses on and nearby intersections in such shaped fractures,therefore it is necessary to understand and quantify them.In this study,both laboratory experiments and numerical simulations were performed to investigate the total head loss on and nearby the intersections as well as the local head loss exactly on the intersections,which were not usually paid sufficient attention or even ignored.The investigation results show that these two losses account for 29.17%-84.97%and 0-73.57%of the entire total head loss in a fracture,respectively.As a result,they should be necessarily considered for groundwater modeling in fractured rocks.Furthermore,both head losses become larger when aperture and flow rate increase and intersection length decreases.Particularly,the ratios of these two head losses to the entire total head loss in a fracture could be well statistically explained by power regression equations with variables of aperture,intersection length,and flow rates,both of which achieved high coefficients of determination.It could be feasible through this type of study to provide a way on how to adjust the groundwater head from those obtained by numerical simulations based on the traditional linear flow model.Finally,it is practicable and effective to implement the investigation approach combining laboratory experiments with numerical simulations for quantifying the head losses on and nearby the intersections between disc-shaped fractures.

全球海啸相关研究进展综述

With the advancement of the global economy,the coastal region has become heavily developed and densely populated and suffers significant damage potential considering various natural disasters,including tsunamis,as indicated by several catastrophic tsunami disasters in the 21st century.This study reviews the up-to-date tsunami research from two different viewpoints:tsunamis caused by different generation mechanisms and tsunami research applying different research approaches.For the first issue,earthquake-induced,landslide-induced,volcano eruption-induced,and meteorological tsunamis are individually reviewed,and the characteristics of each tsunami research are specified.Regarding the second issue,tsunami research using post-tsunami field surveys,numerical simulations,and laboratory experiments are discussed individually.Research outcomes from each approach are then summarized.With the extending and deepening of the understanding of tsunamis and their inherent physical insights,highly effective and precise tsunami early warning systems and countermeasures are expected for the relevant disaster protection and mitigation efforts in the coastal region.

物理生成的长峰不规则波的非高斯统计特性

An experimental study is presented on the non-Gaussian statistics of random unidirectional laboratory wave fields described by JONSWAP spectra.Relationships between statistical parameters indicative of the occurrence of largeamplitude waves are discussed in the context of the initial steepness of the waves combined with the effect of spectral peakedness.The spatial evolution of the relevant statistical and spectral parameters and features is also considered.It is demonstrated that over the distance the spectra exhibit features typical for developing nonlinear instabilities,such as spectral broadening and downshift of the peak,along with lowering of the high-frequency tail and decrease of the peak magnitude.The wave fields clearly show an increase of third-order nonlinearity with the distance,which can be significant,depending on the input wave environment.The steeper initial conditions,however,while favouring the occurrence of extremely large waves,also increase the chances of wave breaking and loss of energy due to dissipation,which results in lower extreme crests and wave heights.The applied Miche-Stokes-type criteria do confirm that some of the wave extremes exceed the limiting individual steepness.Eventually,this result agrees with the observation that the largest number of abnormal waves is recorded in sea states with moderate steepness.

Experimental arena settings might lead to misinterpretation of movement properties

Movement is an important animal behavior contributing to reproduction and survival.Animal movement is often examined in arenas or enclosures under laboratory conditions.We used the red flour beetle(Tribolium castaneum)to examine here the effect of the arena size,shape,number of barriers,access to the arena's center,and illumination on six movement properties.We demonstrate great differences among arenas.For example,the beetles moved over longer distances in clear arenas than in obstructed ones.Movement along the arena's perimeter was greater in smaller arenas than in larger ones.Movement was more directional in round arenas than in rectangular ones.In general,the beetles stopped moving closer to the perimeter and closer to corners(in the square and rectangular arenas)than expected by chance.In some cases,the arena properties interacted with the beetle sex to affect several movement properties.All these suggest that arena properties might also interact with experimental manipulations to affect the outcome of studies and lead to results specific to the arena used.In other words,instead of examining animal movement,we in fact examine the animal interaction with the arena structure.Caution is therefore advised in interpreting the results of studies on movement in arenas under laboratory conditions and we recommend paying attention also to barriers or obstacles in field experiments.For instance,movement along the arena's perimeter is often interpreted as centrophobism or thigmotaxis but the results here show that such movement is arena dependent.

高压输电线路雷击闪络的实验室研究(英文)

This paper presents an investigation on the attractive width of high voltage transmission lines to lightning strikes.In order to design the optimal lightning protection,the estimated number of lightning flashes on the line, which is based on its attractive width,needs to be determined.The investigation was performed using experiments with model tests at the Mississippi State University High Voltage Laboratory.For laboratory experiments,a total of 2,100 negative and positive switching impulse voltages were applied to transmission line models from a conducting rod,which represented a lightning downward leader.Different tested models of transmission lines on a scale of 1:100 were used.The effects of overhead ground wires,phase conductors,tower structures,and the magnitude and polarity of lightning strokes were also studied.The attractive width increased gradually with the height of overhead ground wires and towers as well as the magnitude of the lightning stroke current.Impulse polarity had an impact on the attractive width,and the attractive width for negative polarity was larger than that for positive polarity.The taller tower had more effect on flash distribution to transmission lines than the shorter one.The experimental results agree with the actual transmission line observations published in literature.The new expressions for the attractive width of transmission lines,based on the experimental results,were established.The accurate estimation of the attractive width can help electric power utilities plan transmission systems reliably and economically.The detailed description of the background problem,proposed method,experimental results,and analysis are presented in this paper.

Water migration in subgrade soil under seasonal freeze-thaw cycles in an alpine meadow on the Qinghai-Tibet Plateau

Highway frost heave and thawing settlement caused by water migration towards the freezing front and ice lens development is widespread in the alpine meadow area of the southeast QinghaiTibet Plateau(QTP). A laboratory experiment on a highway reconstruction and expansion project in the QTP was carried out in this work to analyze the effects of fine particle content, initial water content, and the number of freeze-thaw cycles(FTCs) on frost depth, temperature gradient(Grad T), total water intake, and water intake flux. Based on the results of the laboratory experiment, a modified model of migration potential related to fine particle content, freeze-thaw history, and freezing time was established. The results show that, with the increase of fine particle content, the frost depth of soil decreases, the curve of total water intake over time is transformed from an Sshape to an arch, and the curve of water intake flux over time is transformed from a peak shape to descending shape. The variation trend of migration potential with freezing time and the freeze-thaw history is the same as that of water intake flux with freezing time and freeze-thaw history. The variation trend of soil intake flux can be used as a reference to determine the variation trend of soil migration potential. This study provides a reference for the design and construction of highway subgrade in the alpine meadow area of the QTP.

Applying a modified conduit flow process to understand conduit-matrix exchange of a karst aquifer

Due to the high heterogeneity and complexity of water flow movement for multiple karst water-bearing mediums,the evaluation,effective development,and utilization of karst water resources are significantly limited.Matrix flow is usually laminar,whereas conduit flow is usually turbulent.The driving mechanisms of water exchange that occur between the karst conduit and its adjacent matrix are not well understood.This paper investigates the hydrodynamic characteristics and the mechanism of flow exchange in dual water-bearing mediums(conduit and matrix)of karst aquifers through laboratory experimentation and numerical simulation.A karst aquifer consisting of a matrix network and a conduit was proposed,and the relationship between the water exchange flux and hydraulic head differences generated from the laboratory experiments was analyzed.Two modes of experimental tests were performed with different fixed water level boundaries in the laboratory karst aquifer.The results indicate that the water exchange capacity was proportional to the square root of hydraulic head differences.The linear exchange term in the conduit flow process(CFP)source program was modified according to experimental results.The modified CFP and the original CFP model experimental data results were compared,and it was found that the modified CFP model had better fitting effects.These results showed that the water exchange mechanism between conduit and matrix is very important for solid-liquid interface reaction,water resource evaluation,and understanding of karst hydrodynamic behavior.

Do experienced subjects bias experimental results?Evidence from 16 laboratories in six countries

This paper addresses an area of growing concerns for laboratory researchers:is subjects’behaviour affected by prior experiences in laboratory experiments?We address the question with a large and highly diverse international dataset and an operationalisation strategy that allows our findings to cohere with previous work while shedding new light on future research.The findings presented in this article are drawn from original data gathered as part of one of the largest tax compliance experiments ever conducted,involving more than 3,000 participants in six countries,across 16 different laboratories.Our results reveal that subjects’behaviour correlates with their past experimental experiences,in a way that could bias results and compromise a study’s external validity.However,this change in behaviour due to experiences occurs only after subjects have participated in at least two previous laboratory experiments.The findings have implications not just for tax compliance research,but for allocation experiments more generally and for participant recruitment particularly.

Whistleblowing and tax evasion:Experimental evidence

In a tax compliance experiment we manipulate various dimensions to isolate the effects of whistleblowing:whether incomes are homogeneous or heterogeneous;whether whistleblowing is permitted or not;and whether subjects have complete or incomplete information about others’tax evasion.Under complete information,we find that whistleblowing has a strong impact on compliance,reducing the proportion of concealed income and increasing the precision of the auditing procedure.Moreover,the probability of being whistled increases with evasion and rich subjects react to whistleblowing more than poor subjects do.Introducing incomplete information reduces the deterrent effect of whistleblowing,but not among the richest taxpayers.

Changing structure of benthic foraminiferal communities due to declining pH:Results from laboratory culture experiments

The ocean absorbs large amounts of CO_2 emitted from human activities, which results in a decrease in seawater p H.Marine calcifying organisms such as foraminifera, are most likely to be affected by this declining pH. In this study, we collected sediments from five stations of different depths(34–73 m) in a continental shelf of the Yellow Sea. The entire benthic foraminiferal communities together with sea sediments were cultured under three constant pHs(8.3, 7.8, and 7.3) for 6 and 12 weeks in the laboratory to study their responses to pH or incubation time. The microcosm's experimental results obtained showed that most of the foraminiferal community parameters(abundance, species richness, Margalef index, and Shannon-Wiener diversity) decreased significantly(p<0.05) with the decline in pH in all the tested stations. The responses of foraminifera to the decline in p H were species-specific, for instance, Protelphidium tuberculatum and Cribroelphidiumfrigidum were highly sensitive to declining pH and were finally eliminated at low pH, while some species(e.g., Lagenammina atlantica, Verneuilinulla advena, V. propinqua, Haplophragmoides applanata, and H. canariensis) could tolerate low pH and acted as pH-tolerant species. In addition, the proportion of hyaline taxa showed a significant(p<0.05) positive correlation with pH, while agglutinated type showed a negative response. Furthermore, different incubation times(6 and 12 weeks) showed significant effects on the nearshore communities other than the offshore treatments, which were, however, entirely declined after 6 weeks' incubation under low p H manipulation. Our results indicated that nearshore foraminiferal communities showed rather a resilience to the declining p H and the offshore foraminifera, especially those in the central area of the Yellow Sea Cold Water Mass were found to be more sensitive to the decline in pH in the continental shelf sediments of the Yellow Sea.

Experiments and calculations of wave breaking and evolution of wave groups with high steepness

The evolution of the nonlinear wave groups in deep water is investigated through laboratory measurements and numerical analysis.Laboratory experiments are conducted in deep-water wave tank,focusing on the characteristics of breaking waves arising from the evolved wave train.Some quantitative results are obtained for the significant breaking wave train,including the surface elevation time series,the local geometry,and the energy dissipation.A nonlinear model for the evolution of the wave groups in deep water is developed by adding eddy viscosity dissipation terms in the High Level Irrotational Green-Naghdi(HLIGN)equations.The results of the simulation are compared with the laboratory measurements,and good agreement is observed for the evolved wave train.

Analysis of microscopic properties of radiative shock experiments performed at the Orion laser facility

In this work we have conducted a study on the radiative and spectroscopic properties of the radiative precursor and the post-shock region from experiments with radiative shocks in xenon performed at the Orion laser facility. The study is based on post-processing of radiation-hydrodynamics simulations of the experiment. In particular, we have analyzed the thermodynamic regime of the plasma, the charge state distributions, the monochromatic opacities and emissivities, and the specific intensities for plasma conditions of both regions. The study of the intensities is a useful tool to estimate ranges of electron temperatures present in the xenon plasma in these experiments and the analysis performed of the microscopic properties commented above helps to better understand the intensity spectra. Finally, a theoretical analysis of the possibility of the onset of isobaric thermal instabilities in the post-shock has been made, concluding that the instabilities obtained in the radiative-hydrodynamic simulations could be thermal ones due to strong radiative cooling.

Theoretical and Experimental Studies of Seismoelectric Conversions in Boreholes

We present theoretical and experimental studies on the effects of formationproperties on seismoelectric conversions in fluid-filled boreholes. First, we derive thetheoretical formulations for seismoelectric responses for an acoustic source in a borehole.Then, we compute the electric fields in boreholes penetrating formations withdifferent permeability and porosity, and then we analyze the sensitivity of the convertedelectric fields to formation permeability and porosity. We also describe the laboratoryresults of the seismoelectric and seismomagnetic fields induced by an acousticsource in borehole models to confirm our theoretical and numerical developmentsqualitatively. We use a piezoelectric transducer to generate acoustic waves and a pointelectrode to receive the localized seismoelectric fields in layered boreholes and theelectric component of electromagnetic waves in a fractured borehole model. Numericalresults show that the magnitude ratio of the converted electric wave to the acousticpressure increases with the porosity and permeability increases in both fast and slowformations. Furthermore, the converted electric signal is sensitive to the formationpermeability for the same source frequency and formation porosity. Our experimentsvalidate our theoretical results qualitatively. An acoustic wave at a fracture intersectinga borehole induces a radiating electromagnetic wave.

A temperature gradient test system for investigating thermo-mechanical responses of containment materials of underground storage facilities

Underground energy storage is a promising option for the global ambition of moving towards carbon neutrality.To achieve safe and reliable energy storage in underground caverns,it is essential to understand the contributions of thermal and mechanical loads to the deformation of containment materials(e.g.,concrete and geomaterials)and to forecast potential risks related to unexpected failure of these materials.A temperature gradient test system is developed to investigate the thermo-mechanical responses of containment materials under simulated temperature gradient and earth pressure conditions.The test system has advantages of establishing a temperature gradient of over 400
C/m across a large-scale specimen and examining the resulting strain based on the digital image correlation analysis.This study sheds light on 3 typical applications of the test system to examine the thermal and mechanical responses of intact limestone,flawed limestone,and fractured concrete.The results demonstrate that the mechanical load mainly controls the strain evolution of the intact limestone,while the thermal load strongly affects the strain evolution around the circular hole.The failure pattern of concrete primarily influences the mechanically induced strain,and the thermally induced strain is insensitive to the concrete failure.This test system can be modified and upgraded to study various research topics related to underground energy storage.