Geometrical considerations in the acquisition of borehole interferometric data for imaging near-vertical features: Design of field experiments

Geophysics ◽  
2013 ◽  
Vol 78 (3) ◽  
pp. K1-K10 ◽  
Author(s):  
Emma Brand ◽  
Charles Hurich ◽  
Sharon Deemer
Keyword(s):  
Stationary Phase ◽  
Field Experiments ◽  
Hard Rock ◽  
Critical Role ◽  
Seismic Profile ◽  
Dominant Frequency ◽  
Critical Parameters ◽  
Seismic Interferometry ◽  
Surface Source ◽  
Major Factors

Seismic interferometry applied to walkaway vertical seismic profile data has significant potential for imaging the steeply dipping structures often encountered in hard-rock minerals exploration. Using the interferometry process, surface shots can be redatumed to the borehole receivers resulting in virtual shot gathers. The virtual shot gathers can then be processed using a standard common midpoint (CMP) processing flow. Carrying out this procedure for a subvertical borehole results in a geometry that is optimal for imaging structures that are near vertical. Field acquisition parameters play a critical role in recovering reliable virtual source images. We evaluated the major factors that play a role in designing a field acquisition program with the objective of providing guidance to field practitioners. The major issue to be considered is insuring that correlation gathers created in the interferometry process have a stationary phase component that when summed produces events with correct timing and cancellation of nonstationary components. Consistent with previous work, the ray-tracing-based analysis identified the surface source spacing, surface source aperture, and dominant frequency as the most critical parameters. The analysis indicated that because of the high apparent velocities typically encountered in hard rock terrains, a surface source spacing of 20 m and an aperture of 1000 m will result in stationary phase components and avoid spatial alias in the correlation gathers for frequencies as high as 80 Hz. However, closer spacing of the surface sources provided more traces in the correlation gathers resulting in fewer artifacts during summation. These results were further verified by acoustic wave modeling that provided data from more complex targets that were processed through a complete interferometry and CMP flow. The analysis indicated that with care in designing field acquisition parameters, seismic interferometry is realizable within the terrain and access restrictions imposed by many mining camps.

Genome-wide identification of AP2/ERF transcription factors in mungbean (Vigna radiata) and expression profiling of the VrDREB subfamily under drought stress

2018 ◽  
Vol 69 (10) ◽  
pp. 1009 ◽  
Author(s):  
Abdullahi Muhammad Labbo ◽  
Maryam Mehmood ◽  
Malik Nadeem Akhtar ◽  
Muhammad Jawad Khan ◽  
Aamira Tariq ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Drought Stress ◽  
Stress Tolerance ◽  
Vigna Radiata ◽  
Critical Role ◽  
Drought Stress Tolerance ◽  
Legume Crop ◽  
Genome Wide ◽  
Responsive Element ◽  
Major Factors

Mungbean (Vigna radiata L.) is a valuable legume crop grown in tropical and subtropical areas of Asia. Drought is one of the major factors hindering its growth globally. APETALA2/ethylene-responsive element factor binding proteins (AP2/ERF) are an important family of plant-specific transcription factors (TFs) involved in drought-stress tolerance. We identified 71 AP2/ERF TFs in the mungbean genome by using bioinformatics tools and classified them into subfamilies: AP2 (16 members), ERF (22), RAV (2), DREB (30) and soloist (other proteins with no domain, 1). Members of DREB play a critical role in drought-stress tolerance. Ten-day-old mungbean plants cv. AZRI-06 were exposed to drought stress by complete withholding of water for 7 days. Root samples were collected from control and drought-stressed plants, and the expression pattern of 30 identified VrDREB genes was determined by qPCR. Most VrDREB genes exhibited differential expression in response to drought. Five genes (VrDREB5, VrDREB12, VrDREB13, VrDREB22, VrDREB30) were highly expressed under drought stress and might be considered excellent candidates for further functional analysis and for improvement of mungbean drought tolerance.

Walkabove VSP with seismic-while-drilling technology: flawless operation in a highly deviated well

2013 ◽  
Vol 53 (2) ◽  
pp. 454
Author(s):  
Adrian Cristian Sanchez Rodriguez ◽  
Leon Dahlhaus ◽  
Konstantin Galybin ◽  
Andrew Vigor ◽  
Grant Skinner ◽  
...  
Keyword(s):  
Seismic Profile ◽  
Geological Structure ◽  
Surface Source ◽  
North West ◽  
The North ◽  
Bottom Hole ◽  
Surface Time ◽  
Drilling Technology ◽  
Bottom Hole Assembly

SWD was recently used in the North West Shelf of Australia to acquire time-depth measurements and to obtain a vertical seismic profile (VSP) while pulling out of hole. The use of SWD technology greatly enhanced the understanding of geology by acquiring a more precise geophysical picture of the subsurface, leading to better understanding of the subsurface and placement of wells in the future. A vertical incidence VSP was acquired in an offshore deviated well for a client on the Australian North West Shelf. The data was acquired using a moving-surface source, suspended from a boat, and a four-component downhole sensor in the bottom hole assembly (BHA). The downhole data was acquired using three orthogonal geophones and a single hydrophone measurement at each VSP level. This was recorded while pulling out of hole, and processed once the tool was on surface. Time picking accuracy of the downhole data is ±0.5 ms with the frequency range 6–90Hz, both comparable to Wireline. The repeatability of the hydrophone and geophone time picks was also excellent with the average difference being 0.2 ms and maximum 0.8 ms. High resolution VSP images beneath the well in addition to corridor stacks were derived from the geophone and hydrophone data, showing the geological structure of the reservoir. The quality of the data acquired allowed the client to remove the need for a wireline VSP run; it, therefore, saved significant rig time and costs associated with it, reduced the chances of getting stuck, and significantly reduced the seismic uncertainty.

Crosscoherence-based interferometry for the retrieval of first arrivals and subsequent tomographic imaging of differential weathering

Geophysics ◽  
2019 ◽  
Vol 84 (4) ◽  
pp. Q37-Q48 ◽  
Author(s):  
Joachim Place ◽  
Deyan Draganov ◽  
Alireza Malehmir ◽  
Christopher Juhlin ◽  
Chris Wijns
Keyword(s):  
Seismic Waves ◽  
Seismic Velocity ◽  
Signal To Noise Ratio ◽  
Seismic Profile ◽  
Seismic Interferometry ◽  
Near Surface ◽  
Tomographic Images ◽  
Traveltime Tomography ◽  
Seismic Methods ◽  
Source Signal

Exhumation of crust exposes rocks to weathering agents that weaken the rocks’ mechanical strength. Weakened rocks will have lower seismic velocity than intact rocks and can therefore be mapped using seismic methods. However, if the rocks are heavily weathered, they will attenuate controlled-source seismic waves to such a degree that the recorded wavefield would become dominated by ambient noise and/or surface waves. Therefore, we have examined the structure of differential weathering by first-break traveltime tomography over a seismic profile extending approximately 3.5 km and acquired at a mining site in Zambia using explosive sources and a source based on the swept-impact seismic technique (SIST). Seismic interferometry has been tested for the retrieval of supervirtual first arrivals masked by uncorrelated noise. However, use of crosscorrelation in the retrieval process makes the method vulnerable to changes in the source signal (explosives and SIST). Thus, we have developed a crosscoherence-based seismic-interferometry method to tackle this shortcoming. We investigate the method’s efficiency in retrieving first arrivals and, simultaneously, correctly handling variations in the source signal. Our results illustrate the superiority of the crosscoherence- over crosscorrelation-based method for retrieval of the first arrivals, especially in alleviating spurious ringyness and in terms of the signal-to-noise ratio. These benefits are observable in the greater penetration depth and the improved resolution of the tomography sections. The tomographic images indicate isolated bodies of higher velocities, which may be interpreted as fresh rocks embedded into a heavily weathered regolith, providing a conspicuous example of differential weathering. Our study advances the potential of seismic methods for providing better images of the near surface (the critical zone).

scholarly journals Effect of Straw Mulch on Soil Evaporation during Freeze–Thaw Periods

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1689 ◽  
Author(s):  
Junfeng Chen ◽  
Xue Xie ◽  
Xiuqing Zheng ◽  
Jing Xue ◽  
Chunyan Miao ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Field Experiments ◽  
Principal Component ◽  
Coverage Rate ◽  
Soil Evaporation ◽  
Soil Water Storage ◽  
Freeze Thaw ◽  
Straw Mulch ◽  
Major Factors ◽  
Semi Arid

Reducing soil evaporation is important to alleviate water shortages in arid and semi-arid regions. The objective of this work was to reveal the effect of straw mulch on soil evaporation based on field experiments during a freeze–thaw period in Northern China. Four soil surface mulch treatment modes were investigated: Bare soil (BS), 1 cm thick straw mulch with 100% coverage rate (J1), 2 cm thick straw mulch with 100% coverage rate (J2), and 2 cm thick straw mulch with 50% coverage rate (J3). Principal component analysis was used to analyze the major factors influencing soil evaporation in three freeze–thaw stages. The results show that cumulative soil evaporation decreased with increased straw mulch thickness and coverage rate. The effect of straw mulching on soil evaporation was obvious during the stable freezing period, and soil evaporation with straw mulch treatments was reduced by 49.0% to 58.8% compared to BS treatment, while there was little difference for straw mulch treatments in the thawing stage. The relationship between cumulative soil evaporation under different straw mulch modes and time was well fitted by the power function. In the unstable freezing stage, the major factors for all treatments influencing soil evaporation were surface soil temperature and water surface evaporation; in the stable stage, they were solar radiation and relative humidity, and in the thawing stage, they were solar radiation and air temperature. The research results can provide a basis for addressing soil water storage and moisture conservation and restraining ineffective soil evaporation in arid and semi-arid areas.

scholarly journals Efficacy of Area-Wide Inoculum Reduction and Vector Control on Temporal Progress of Huanglongbing in Young Sweet Orange Plantings

Plant Disease ◽  
2013 ◽  
Vol 97 (6) ◽  
pp. 789-796 ◽  
Author(s):  
Renato B. Bassanezi ◽  
Luiz H. Montesino ◽  
Nelson Gimenes-Fernandes ◽  
Pedro T. Yamamoto ◽  
Tim R. Gottwald ◽  
...  
Keyword(s):  
Vector Control ◽  
Field Experiments ◽  
Sweet Orange ◽  
Control Strategies ◽  
Disease Incidence ◽  
Critical Role ◽  
Control Program ◽  
Candidatus Liberibacter ◽  
Local Vector ◽  
Temporal Progress

Huanglongbing (HLB), caused by ‘Candidatus Liberibacter’ spp. and transmitted by the Asian citrus psyllid Diaphorina citri (ACP), is an important threat to citrus industries worldwide, causing significant yield loss. The current recommended strategies to manage HLB are to eliminate HLB-symptomatic trees to reduce sources of bacterial inoculum and to apply insecticides to reduce psyllid vector populations. The objective of this study was to assess the effectiveness and the importance of both strategies applied within young citrus plots (local management), in different frequencies and combinations, on HLB temporal progress. Two factorial field experiments, E1 and E2, were initiated in a new plantation of sweet orange in an HLB epidemic region of Sao Paulo, Brazil, in October 2005 and May 2006, respectively. Local inoculum reduction (tree removal) intervals for E1 were every 4, 8, and 16 weeks and, for E2, every 2, 4, 12, and 26 weeks. Local vector control strategies for E1 were no control, program A (PA), and program B (PB); and, for E2, no control and program C (PC), as follows. Psyllids were controlled with two 56-day-interval soil or drench applications of systemic insecticides concurrently with the rainy season each year and, during the rest of the year, with insecticide sprays every 28 days for PA and every 14 days for PB and PC. Regional HLB management was present for E1 and absent for E2. The beginning of the HLB epidemic was delayed for 10 months in E1 compared with appearance of the first diseased tree in E2 but wasn't affected by different local strategies in either experiment. After 60 (E1) and 53 (E2) months, the HLB incidence and progress rates were not affected by different frequencies of local inoculum reduction in either experiment, and were different only in plots with and without local vector control in E2. In E1, the disease incidence was reduced by 90% and the disease progress rate by 50% in plots both with and without vector control. These reductions were explained by smaller psyllid populations and lower frequency of bacterialiferous psyllids in E1 compared with E2. Annual productivity increased over time in E1, as expected for young plantings, but remained stable or decreased in E2. These results confirm that immigration of bacterialiferous ACP vectors plays a critical role in HLB epidemics and suggest that area-wide inoculum reduction and ACP management strongly affect HLB control.

In situ study of volcanic ash resuspension using a portable wind tunnel.

2020 ◽  
Author(s):  
Jacopo Taddeucci ◽  
Elisabetta del Bello ◽  
Jonathan P Merrison ◽  
Keld R Rasmussen ◽  
Jens J Iversen ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
High Speed ◽  
Volcanic Ash ◽  
Field Experiments ◽  
Critical Parameters ◽  
Test Bed ◽  
High Definition ◽  
Sustained Activity

<p>The resuspension of volcanic ash deposits by wind is a well-known source of hazard following explosive eruptions. Besides the mail control exerted by the local wind field, ash resuspension is also influenced by: 1) atmospheric humidity; 2) features of the deposit (grain size distribution, sedimentary structures, etc.), and 3) features of the substrate (i.e. moisture, roughness). Ash resuspension is modeled using numerical simulations, which however require physical characterization and identification of the critical parameters controlling ash resuspension. Wind tunnel studies on volcanic particles are very limited and restricted to laboratory parameterizations, with in-situ effects not been parameterized. We tested field experiments of volcanic ash resuspension developing a portable wind tunnel and deploying on proximal (3 km) ash deposits from the semi-sustained activity of Sakurajima volcano (Japan) and from distal (250 km ca.) ash deposits from the 2011 Cordon Caulle eruption (Chile). The wind tunnel is calibrated with both LDA and pitot tubes measurements. The device allows generating a controlled wind profile within a 110x12x12 cm test section, which is placed directly on an untouched test bed of naturally deposited ash. Two types of experiments were performed: 1) ramp up speed experiments, where the wind speed is increased until reaching the threshold friction speed on four different substrates; 2) constant speed experiments, where three wind speed values where kept for 20 minutes using the same substrate. The threshold friction speed is measured with a hot wire anemometer, and the movement of resuspended ash is detected by means of multiple high speed and high definition digital camcorders. In-situ measured threshold friction speeds are compared to 1) in situ observed episodes of resuspension driven by local winds and 2) laboratory determination of threshold friction speed in controlled environmental conditions, and using the same ash deposited homogeneously.</p><p> </p>

scholarly journals σ B contributes to Listeria monocytogenes invasion by controlling expression of inlA and inlB

Microbiology ◽  
2005 ◽  
Vol 151 (10) ◽  
pp. 3215-3222 ◽  
Author(s):  
Heesun Kim ◽  
Hélène Marquis ◽  
Kathryn J. Boor
Keyword(s):  
Listeria Monocytogenes ◽  
Stationary Phase ◽  
Critical Role ◽  
Virulence Gene ◽  
Bacterial Invasion ◽  
Dependent Manner ◽  
Intestinal Epithelial ◽  
Phagocytic Cells ◽  
Invasion Mechanisms ◽  
Human Enterocyte

The ability of Listeria monocytogenes to invade non-phagocytic cells is important for development of a systemic listeriosis infection. The authors previously reported that a L. monocytogenes ΔsigB strain is defective in invasion into human intestinal epithelial cells, in part, due to decreased expression of a major invasion gene, inlA. To characterize additional invasion mechanisms under the control of σ B, mutants were generated carrying combinations of in-frame deletions in inlA, inlB and sigB. Quantitative assessment of bacterial invasion into the human enterocyte Caco-2 and hepatocyte HepG-2 cell lines demonstrated that σ B contributes to both InlA and InlB-mediated invasion of L. monocytogenes. Previous identification of the σ B-dependent P2 prfA promoter upstream of the major virulence gene regulator, positive regulatory factor A (PrfA), suggested that the contributions of σ B to expression of various virulence genes, including inlA, could be at least partially mediated through PrfA. To test this hypothesis, relative invasion capabilities of ΔsigB and ΔprfA strains were compared. Exponential-phase cells of the ΔsigB and ΔprfA strains were similarly defective at invasion; however, stationary-phase ΔsigB cells were significantly less invasive than stationary-phase ΔprfA cells, suggesting that the contributions of σ B to invasion extend beyond those mediated through PrfA in stationary-phase L. monocytogenes. TaqMan quantitative reverse-transcriptase PCRs further demonstrated that expression of inlA and inlB was greatly increased in a σ B-dependent manner in stationary-phase L. monocytogenes. Together, results from this study provide strong biological evidence of a critical role for σ B in L. monocytogenes invasion into non-phagocytic cells, primarily mediated through control of inlA and inlB expression.

Experimental Evaluation of Vibration Effects Induced by Planed Railway Line on Surrounding Historic Tower

2014 ◽  
Vol 501-504 ◽  
pp. 861-866
Author(s):  
Yuan Tian ◽  
Nan Zhang ◽  
Wei Guo Yang ◽  
Jia Ming Niu
Keyword(s):  
Field Experiments ◽  
Dominant Frequency ◽  
Vibration Velocity ◽  
Vibration Source ◽  
Vibration Level ◽  
Frequency Range ◽  
Structural Vibrations ◽  
Upward Trend ◽  
Railway Line ◽  
Different Types

Using field experiments, the vibration effects of historic tower induced by planed railway line are estimated. The vibrations include the construction vibration and the traffic-induced vibration. The results show that the blasting construction leads to the significant increase in vertical velocity and acceleration. There is no difference between the background vibration of field and foundation of tower. Different types of the sites soil around the tower cause little change. Each measurement time showed an upward trend of vibration level with the increase of frequency. The closer the tower is to the vibration source, the larger the structural vibrations would be. The dominant frequency range for highway-induced vibration is 10-20Hz. For train-induced vibration, the dominant frequency range is more than 40Hz. Surface waves will result in amplification phenomenon of vibration velocity of ancient structures within a certain range.

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