bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of different species of cyanobacteria on the rice yield and nitrogen use efficiency under different levels of nitrogen fertilizer on Alluvial West Java
Authors: Purwani J , Pratiwi E , Sipahutar I A , Husnain
Published: February 2021

Cyanobacteria or blue-green algae play an important role in rice cultivation. Nitrogen-fixing bacteria Cyanobacteria are found in rice fields, some of which can fix N2 up to 30%, produce some phytohormones, vitamins, amino acids, and organic acids increase soil fertility and rice productivity. The study was conducted in Alluvials wetland rice in Jatitujuh, Majalengka Regency, West Java. This research aimed to analyze the influence of cyanobacteria in increasing rice yield and the efficiency of inorganic N fertilizers. The study was arranged in a randomized block design with two factors. The first factor was the cyanobacteria formula, i.e.: (1) without cyanobacteria, (2) Pseudanabaena sp.+Chlorogloea sp., (3) Pseudanabaena sp.+Nostoc sp., (4) Chlorogloea sp.+Nostoc sp. The second factor was the dose of N fertilizer (0%, 50%, 75% and 100%). The highest rice yield obtained by Chlorogloea sp.+Nostoc sp with 100% N, increased by 14.75%. Application of Pseudanabaena sp. + Nostoc sp. was increased rice grain yield and straw biomass by 11.47% and 37.49%, reduced N fertilizer by 25 to 50%, and increased nutrient uptake of N, P, K by 43.73%, 34.80 %, 34.40%. Using cyanobacteria is a promising strategy to increase rice yield and reduce chemical fertilizers.
Analysis of landscape changes using high-resolution satellite images at former rice fields after earthquake and liquefaction in Central Sulawesi Province
Authors: Nanda G I , Mulyani A
Published: February 2021

An earthquake and liquefaction in Palu and Sigi on September 28, 2018, caused serious damage in the rice fields and agricultural infrastructure. The aim of this research was studying and mapping the impact of the disasters by using high-resolution satellite images and field verification. This research uses a visual analysis method to compare images before and after the disasters. The results showed that 6,467 ha of rice fields affected by the disaster. The heavy damaged rice fields were caused by earthquakes, damaged river embankment, and liquefaction. The landscape with undulating slope having height difference of 1 to 5 m, reversed soil surface, crack width > 100 cm, damage on the irrigation system, and sand boiling, were naturally cannot be used again for rice fields. It can be used as tourism spot or historical sites with natural landscape. Whereas rice fields with undulating slope having height difference 20 to 100 cm, crack width up to 100 cm, and sand boiling were classified as moderate. The lightly damaged rice fields could not be planted because the irrigation system was destroyed. It can be used as rice fields after repairing the irrigation system to support water availability.
Model development of sustainable wetland rice farming based on rice estate community and smart farming
Authors: Rachman L M , Saleh A , Wetik J D , Namuzadi N , Ain A Q
Published: February 2021

Crucial issues in rice fields production in Indonesia are narrow planting areas, small farming scale and improper cultivation techniques. The Indonesian government also faced issues and problems regarding fulfilment the need of rice-farm area due to the conversion of intensive rice fields to non-agriculture. Efforts to develop integrated and sustainable rice field agriculture are needed to overcome the threat of rice field reduction, increase the productivity of rice fields, and increase farmers’ income and welfare. The intention of this study was to develop a model of rice field in an integrated and sustainable manner based on Rice Estate Community and Smart Farming (REC-SF). To get easily implemented model, participatory method was used through series of audiences and focus group discussion activities involving the main stakeholders. As a breakthrough for traditional agricultural solutions on narrow land, this model included land consolidation to reach minimum rice field area for profitable economic scale, strengthening institutional system, productivity target along with required cultivation inputs and techniques, support for information technology system, agroindustry, and marketing-selling reinforcement. Developed REC-SF model is expected to be more easily implemented and accepted by the farmers to achieve a collective farm business in a large rice-farm area.
Research on seismic exploration techniques and methods in urban environment of loess plateau
Authors: Tian A-Wei , Li Zhong-Sheng , Liu Si-Tong , Wang Zhong-Sheng , Zheng Ge-Hui , Yuan Zi-Heng , Huang Hua
Published: February 2021

Seismic wave energy being absorbed strongly in thick loose loess stratum is a major problem that seismic exploration has to face. In the urban environment, this problem is particularly prominent due to the inability to use explosives, borehole explosion, and large-scale 3D observation methods to increase fold number. To solve this difficult problem, a series of seismic exploration effect tests were carried out in Shaoling Plateau, a southern suburb of Xi’an City. A large-tonnage vibroseis, 28-ton vibrator vehicle, was selected as seismic source. By comparing and analyzing the effects of various vibrating parameter of vibrator vehicle, cooperating with different model geophones acquisition, and using appropriate observation system, we had figured out the feasible parameters for the source excitation and data acquisition in the field working area. Based on the results of above test, a nearly 7 km long seismic survey line was completed with pretty good data acquisition, and the expected exploration aims were well achieved.
Research on highly sensitive electromagnetic method based on balance coil for underground metal detection
Authors: Zhang Bo , Yin Guangyao , Zhang Yang , Lin Jun
Published: February 2021

In order to solve the problem of low signal-to-noise ratio and serious primary field interference of frequency domain electromagnetic system for urban underground metal, a balanced coil structure based on LC resonance technique is proposed in this paper. The proposed technique uses the balance coil to eliminate the interference of the primary field, and LC resonance technique is adopted to increase the signal amplitude and improve the signal sensitivity and signal-to-noise ratio. An experiment was conducted by the system built on this proposed technique. The results show that the primary magnetic field can be suppressed by the balance coil and the signal-to-noise ratio can be improved by LC resonance technique through experiments.
Feasibility study of detecting gas leakage in buried pipeline based on resistivity method
Authors: Sun Binyang , Zhang Pingsong , Guo Liquan , Fu Maoru , Fu Ming , Cheng Wenkang
Published: February 2021

Urban gas pipe networks are mostly buried underground and it is hard to monitor, detect and locate the leakage area effectively. The primary structure of the soil could change before and after aeration, so the detection method of gas leakage based on resistivity method has some physical basis. Based on the theoretical research of the predecessors, corresponding geoelectric model is established by combining two typical gas leakage geological models to study the influences of testing device, leakage mode and leakage intensity on the distribution characteristics of gas leakage geoelectric field. Obtained by using forward and inverse numerical computation methods, the theoretical resistivity profile image is compared with the resistivity profile measured by outdoor gas leakage simulation experiment to evaluate comprehensively the feasibility and effectiveness of detecting gas leakage of buried pipelines based on resistivity differential characteristics. The research results show that resistivity method could describe the spatial distribution location effectively and the electrical resistivity has positive correlation with leakage pressure. And the pressure inside the pipeline also determines the migration path of the gas leakage, which diffuses outwards in the shape of “smoke ring” in high-pressure leakage.
Research on towed TEM on off-centre self-compensation technology for urban underground space detection
Authors: Zhang Yang , Lin Jun
Published: February 2021

Transient electromagnetic (TEM) is a geophysical method that can obtain the electrical information of underground media. It will provide strong technical support for the safe development and operation of urban underground space. However, the coupling effect of the transmitting current on the receiving loop leads to the shallow blind area of TEM. Especially, the coupling effect is more serious when the multi-turn and small-size coil structure is required because of the limitation of urban buildings and ground facilities. To solve these problems, this paper proposes a towed TEM technology based on off-centre self-compensation with the small size structure. The new technology adopts the idea of non-coplanar eccentricity structure to design a self-compensation system, which can eliminate the coupling effect. In this paper, the distribution of primary field in receiving coil is studied, and the key structural parameters of transmitting coil and receiving coil is obtained by theoretical model. The experimental results show that the towed TEM system based on the new technology can directly obtain pure secondary field signal. Compared with other TEM structures, it has higher tolerance for physical size error and higher practicability. The towed TEM technology proposed in this paper will provide a theoretical basis for the realization of blind area free, high-speed and accurate scanning measurement of urban underground space.
Wavefield reconstruction inversion in the frequency domain of on-ground GPR data
Authors: Feng Deshan , Ding Siyuan , Wang Xun
Published: February 2021

Full waveform inversion (FWI) is one of the most promising techniques for the quantitative characterization of the shallow subsurface of the Earth. However, the conventional FWI with the reduced approach is highly nonlinear, a challenging source of which is the cycle skipping. It would drive FWI to spurious local minima as soon as the initial model parameters are not accurate enough. By introducing a non-negative penalty term and a penalty parameter, wavefield reconstruction inversion (WRI) extends the search space of full waveform inversion, relaxes the requirement to satisfy exactly the wave equation at each iteration, and mitigates some of the problems related to poor start models, which leads to the cycle skipping phenomenon. Moreover, WRI breaks down FWI into two linear sub-problems and reconstruct the wavefield and estimate the model parameter in a loop and there is no need to update and store the wavefield. In this paper, we perform the model reconstruction of on-ground GPR using WRI in the frequency domain by inverting data of a limited number of frequency components, and compare the results of it with that of the conventional FWI. With a limited illumination of the subsurface, WRI with small penalty parameters has a positive performance.
Estimating water content of unsaturated sandy soils by GPR during a drainage experiment
Authors: Zhang M. H. , Bano M. , Feng X. , Lesparre N. , Girard J. F. , Razakarisoa O. , Belfort B. , Lehmann F. , Friedmann P.
Published: February 2021

This study shows how to estimate water content of unsaturated sandy soils from ground-penetrating radar (GPR) data acquired during water drainage experiment. Using the Topp equation, water content can be converted to dielectric permittivity. Afterwards, based on 1D forward modeling method a GPR synthetic trace is generated. Finally, a trial-and-error match of modeled and observed GPR traces was performed to estimate the optimum set of parameters characterizing the materials composing the soil. According to the comparison of the modeling signal and the real signal, we go back to update the water content. Repeating the procedure until the modeling signal fits the real signal very well. We used this procedure to obtain the evolution of water content of unsaturated sandy soils. The method is presented on drainage experiment carried out on unsaturated sandy soil of a large-controlled experimental site. In order to follow the change of the water level, we measured GPR profiles at different times and picked up four GPR profiles, then the same trace (No. 700) were picked up on each GPR profile and estimated the water content from each signal.
Calibration of Interface Induced Polarization for Full Polarimetric Ground Penetrating Radar
Authors: Dong Zejun , Feng Xuan , Liu Cai , Liang Wenjing , Zhou Haoqiu
Published: February 2021

The traditional ground penetrating radar (GPR) uses only one type of antenna for data acquisition, and only obtains single polarization data of targets. It can not fully describe the various properties of the target. Full polarimetric GPR is a new technology that uses four different polarization antennas to measure the target and can receive electromagnetic waves of different polarized directions to describe the polarization effect of targets. However, when the plane electromagnetic wave propagates through the ground surface, the polarized direction will rotate, namely interface induced polarization (IIP), which results in the complex interference embedded in the full polarimetric GPR data. In this research, firstly we discuss the generation of the IIP; subsequently how the IIP affect the full polarimetric GPR data is derived; finally the calibration formula is proposed and is applied to the GPR data processing.
Research and design of tripod-shaped UWB antenna for GPR
Authors: Chen Sibo , Jia Wenfeng , Lin Jun , Zhang Yang
Published: February 2021

In recent years, GPR (Ground Penetrating Radar) has developed rapidly and has played an important role in many fields. As a key part of GPR, the antenna directly affects system performance. A suitable antenna can greatly improve the detection results. To this end, this paper introduces the design of GPR tripod-shaped ultra-wideband antenna based on bow tie antenna. The working bandwidth of the antenna is widened by means of structural loading with truncation as the main part and circular slot at the end of the antenna. Antenna optimization and simulation were performed using ANSYS HFSS (High Frequency Structure Simulator), and the effects of antenna arm truncation length on antenna performance were discussed. Simulation results show that the designed antenna has an operation bandwidth of 700MHz ~ 2GHz and good directionality. It is a miniaturized ultra-wideband antenna suitable for shallow underground pipeline detection.
Passive surface wave imaging with ultrashort noise records in urban areas
Authors: Zhang Hongyu , Xia Jianghai , Pang Jingyin , Cheng Feng , Xing Huaixue
Published: February 2021

Passive surface-wave methods are widely used in urban areas because of their economic efficiency. It usually needs long-time observation to provide phase velocity information at frequencies ranging from several Hz to several tens of Hz. A complex urbanized environment, however, leads to a reduction in acquisition time. Consequently, it’s necessary to extract surface waves with ultrashort traffic noise for engineering applications. Although noise segments are limited in the circumstance of ultrashort acquisition, we still need data selection to avoid stacking neutralization of data with a different signal-to-noise ratio (SNR). Then we compare linear stacking, phase-weighted stacking (PWS), and time-frequency phase-weighted stacking (tf-PWS) through processing one-minute noise records after selection. We can obtain clear and continuous dispersion energy with these three methods. Our results indicate that PWS or tf-PWS has better performance than linear stacking by comparing dispersion energy images, and PWS improves SNR most, strongly contrasting before and after selection.
3D FV Simulation of the Orthogonal Azimuth Electromagnetic Tool Response Logging While Drilling with Multi Annular Grooves Using Potentials
Authors: Yu Lei , Wang Haosen , Wang Hongnian , Yang Shouwen , Yin Changchun
Published: February 2021

In this paper, we use the 3D cylindrical finite volume (3D FV) method to simulate the Orthogonal Azimuth Electromagnetic Tool (OAEMT) responses Logging While Drilling (LWD) according to the special structure of the OAEMT with multi annular grooves. The algorithm allows the solution of the 3D Maxwell’s equation in inhomogeneous media with arbitrary conductivity and magnetic permeability distributions. For improvement of the computational efficiency and the modeling accuracy of the responses of OAEMT with annular grooves filled with ferrite material on steel mandrel in a completely anisotropic media, several techniques are applied: 1) a 3-D cylindrical irregular grid to avoid stair-casing discretization errors in the transmitter, receiver, and mandrel geometries; 2)the electric field continuation to approximate the perfectly electric conducting (PEC) boundary condition for enhancement of the discrete accuracy of the Helmholtz equations on the surface of steel mandrel; 3)the standardization technique to determine the equivalent conductivity and permeability in a non-uniform element; 4) PARDISO direct solver to solve the discrete equation as far as possible for increase of solution stability. We validate the 3D FV results against the numerical mode matching method. The comparisons show very good agreement. Results from 3-D borehole problems in several complex formation conditions involving eccentric tools and dipping beds are given to demonstrate the robustness of the method.
A Co-offset GPR Data Inversion Based on Ray Theory
Authors: Xue Meiqi , Liu Sixin , Lu Qi , Li Hongqing , Wang Yuanxin
Published: February 2021

We use Monte Carlo method to establish a randomly undulating homogeneous layered medium model. Then the co-offset GPR data for the built geological model is simulated by FDTD. The ray-tracing based inversion is applied for interval velocity estimation. During the inversion, the offset between antennas, the velocity value of the first layer, the picked amplitudes values of each reflection layer and reference amplitude are the input data. The thickness and velocity of each layer are calculated by this recursive method. It is proved that this inversion method is feasible for the layered geological model with random undulation, and the fact that undulation, i.e. RMS height and correlation length, influences the inversion results is discussed.
Quasi-3D TEM inversion based on lateral constraint
Authors: Yang Yunjian , Wang Xuben , Liu Xuejun , He Zhangxiang , Mi Xiaoli
Published: February 2021

Quasi-2D inversion based on a lateral constraint is an effective technique for the interpretation of the survey data of transient electromagnetic method (TEM). In this paper, the principle of the lateral constraint is introduced to construct a quasi-3D TEM inversion. Considering that the 3D measuring grid is often not strictly regular, the quasi-3D TEM inversion is constructed using the distance-weighted adjacent stations’ lateral constraint, which can suppress the irrational model mutation generated by single-station 1D inversion, and has no requirement concerning the regularity of the 3D measuring grid. The application in the inversion of field TEM data had verified the effectiveness of this method.
Estimation of near-surface shear-wave velocity by joint inversion of dispersion and HVSR curves of Rayleigh waves from multicomponent active-seismic records
Authors: Mi Binbin , Xia Jianghai
Published: February 2021

The multichannel analysis of surface waves (MASW) method has been widely used for near-surface geophysical and geotechnical studies by using the dispersive characteristics of Rayleigh waves to determine subsurface shear-wave velocity. Commonly, Rayleigh waves are obtained only from the vertical component of P-SV waves. However, the multimodal Rayleigh waves estimated from the horizontal (radial) component data have a different energy distribution compared with those estimated from the vertical component data. The horizontal-to-vertical spectral ratio (HVSR) of Rayleigh waves can be calculated from multicomponent active-seismic records after mode separation. The HVSR peak and trough frequencies are very sensitive to model parameters. We propose to estimate near-surface shear-wave velocity by joint inversion of dispersion and HVSR curves of Rayleigh waves from multicomponent active-seismic records. The proposed joint inversion method can combine the strengths of MASW and HVSR analysis methods. A synthetic example demonstrates that our proposed joint inversion method can provide better constrained and more reliable S-wave velocity in the shallow subsurface.
Application of gravity exploration in urban active fault detection
Authors: Ming Yuanyuan , Niu Xue , Xie Xinglong , Han Zhaohong , Li Qiuchen , Sun Sheng
Published: February 2021

Active faults are a major source of danger for destructive earthquakes. It is an important task for urban earthquake disaster prevention to find out the spatial location and structural attributes of active faults. At present, the most effective geophysical exploration method for detecting and locating urban concealed active faults is shallow seismic exploration, while other geophysical exploration methods are seldom used. In the detection of active faults in Shanghai, seismic exploration is greatly influenced by human factors in urban areas and the efficiency is low. In this paper, through the comparison and analysis of the alignment of seismic and gravity, it is found that the interpretation results of gravity exploration have a good correspondence with the fault structures interpreted by shallow seismic exploration. At the same time, gravity method reveals that there may be other fault anomalies near the fault anomalies identified in previous literature. It illustrates the effectiveness and feasibility of high-precision gravity detection methods in the detection of urban active fault, and also provides important reference significance for active fault detection in other regions.
Urban near-surface imaging from ambient noise tomography using dense seismic networks
Authors: Zhou Changjiang , Xia Jianghai , Zhang Hongyu , Pang Jingyin , Liu Ya , Xi Chaoqiang , Ning Ling , Mi Binbin , Xing Huaixue , Chang Xiaojun
Published: February 2021

It is of scientific and engineering significance to extract surface wave signals from urban ambient noise for fine-scale three-dimensional velocity structure imaging of underground medium. A series of issues such as ambient noise characteristics in urban environment, observation system design and resolution of small-scale imaging, have put forward a lot of new requirements and challenges to traditional methods and technologies. We utilized the dense array with its aperture extend below hundred meters in Hangzhou urban area, to carry out the ambient noise data acquisition experiments within one day. Based on the time-frequency analysis of noise cross-correlations, we conducted surface wave travel time tomography. Finally, the phase velocity slices were inverted to build a three-dimensional S-wave velocity structure, and the profiles were compared with the drilling data for validations. We concluded that these geometry and processing parameters adopted in the urban environment are feasible for near-surface tomography and can meet the demands of three-dimensional geological survey in cities efficiently.
Weighted adaptive finite-element method for 3D transient EM modelling
Authors: Zheng Jianbo , Jia Yajuan , Wang Juanjuan , Liu Yunhe , Qi Yanfu
Published: February 2021

As we know, grid quality can produce big effect on the numerical precision of 3D forward modeling. How to generate high-quality grids becomes the key for high-accuracy EM responses. So we develop a weighted adaptive finite-element method based on hybrid posterior error estimation in combination with unstructured vector finite-element method and Backward Euler scheme. We introduce a weighting factor to adjust the relative weight of posterior errors defined by the continuities of normal current density and tangential magnetic field to create an effective mesh. The numerical experiments on a conductive cube model show that our algorithm performs better than the traditional adaptive method.
A new approach for accurate detection of leakage paths from multiple-wenner arrays inverted resistivity imaging in embankment dam
Authors: Jiang Xiaoyi , Tan Lei , Jiang Shuhai , Lai Sheng
Published: February 2021

Aiming at the difference of hidden danger identification of embankment dams by different arrays of high-density electrical method, a combined inversion method of wenner data volume is proposed to improve the resolution capability of target. The response characteristics of α, β and γ array to the preset model are presented by constructing the geoelectric model of the dam body and the potential leakage hazard in the contact zone. According to the simulation results, different arrays have different detection effects on the same target and the same array has different detection effects on different targets. β array reflects better effect of low resistance area, and γ array is more suitable for dividing dam body boundary, but both have weak anti-interference ability. In addition, the spatial feature information of the target by multiple-wenner inversion is more for the preset model and can effectively compensate for the limitation of a single array. The inversion results based on a priori model can suppress boundary interference and improve the effective identification of preset hidden dangers and boundary. The field test also shows that the anomaly determined by multiple-wenner inversion technology is highly consistent with the leakage site, which effectively improves the accuracy of hidden danger diagnosis.
Application of Magnetic Resonance Detection in Goaf Water in Wuhai
Authors: Li Cong , Zeng Zhaofa , Duan Qingming
Published: February 2021

The mine water disaster in our country has always been the key factor restricting the development of coal production. Due to the unreasonable small coal mine development, mining in some mining area, the destruction of the waterproof coal pillar, lead to the formation of the mined-out area, and goaf water. Because the goaf water does great harm to coal field exploration and development, the prevention and control of goaf water disasters are very important. In this study, aiming at a large area of exploration space, the method of magnetic resonance can be used to detect groundwater, and two magnetic resonance instruments are used to work together. In order to ensure the accuracy and effectiveness of the data collected by the two instruments, improve the efficiency of exploration work and save field exploration time, the basic model of detecting groundwater with magnetic resonance sounding (MRS) method instrument is established, the influencing factors of MRS are analyzed, and the effective signal value of detecting groundwater with MRS instrument is calculated. Through numerical simulation, the optimal distance between the coils laid on the ground when the two MRS instruments are working at the same time is determined. Furthermore, the practicability of the method is verified via a field case performed in a mining area in Wuhai, China. This method can be used as a guide for large-scale field exploration in the future.
Efficient 2D Modeling of Gravity Anomaly in Space-wavenumber Mixed Domain
Authors: Wang Xulong , Liu Jianxin , Guo Rongwen , Liu Rong
Published: February 2021

Forward modeling is the basis of inversion. In order to implement refined inversion imaging and quantitative interpretation of gravity exploration, a high-efficiency and high-precision numerical simulation method of gravity anomalies in mixed space-wavenumber domain is proposed in this paper. By performing one-dimensional Fourier transform, the method transforms the partial differential equations of the two-dimensional space domain problem of gravity anomaly into one-dimensional differential equations with different wave numbers independent of each other. The depth direction is reserved as the spatial domain, and the shallow grid can be properly encrypted and the deep grid to be properly sparse, which taking account of the calculation accuracy, calculation efficiency and simulation of complex terrain. The two-dimensional gravity anomaly forward modeling in the mixed space wavenumber domain makes full use of the fast Fourier transform and the chase method to solve the five-diagonal equations quickly, and realizes the numerical simulation of gravity anomaly with high efficiency and high precision.
Technology of detecting deep underground metal pipeline by magnetic gradient method
Authors: Xi Jianjun , Cui Dandan
Published: February 2021

The application of trenchless technology, such as pipe pulling, pipe jacking, directional drilling and so on, makes the deep buried underground pipeline more and more in the project, and most of the geophysical exploration technology has poor detection effect, which makes it become the difficulty in the underground pipeline detection. This paper mainly expounds and analyzes the principle and construction method of magnetic gradient method for detecting deep underground pipelines, and introduces the application of magnetic gradient method in the detection of deep underground pipelines with two natural gas pipelines in Shijiazhuang road project.
The analysis on PS wave reflection coefficient in equivalent porous fractured media
Authors: Dou Xiying , Wang Enli , Yang Qing , Du Bingyi , Zhang Bo
Published: February 2021

Combining the equivalent fractured media with Thomsen fractured media theory, the anisotropic parameters expressed in compliance are obtained. The new PS wave reflection coefficient formula presented in matrix porosity, fluid type, and fracture density were established. Numerical simulations show that the PS wave reflection coefficient in water-saturated fracture media is more sensitive to the fracture density than that in gas-saturated media; the difference between the reflection coefficients in the gas-saturated and water-saturated state greatly increases when the matrix porosity of fractured media exceeds 0.01. It shows that fracture density and matrix porosity can be used as good fluid indicators in fractured reservoir.
Application of 4D full waveform inversion in the CO2 storage monitoring: a synthetic example
Authors: Huang Zheng , Yan Xuhao , Wang Zhenyi , Zhang Pan , Zhang Fengjiao
Published: February 2021

The time-lapse seismic method is a technique that uses repeated seismic surveys to monitor the dynamic change of reservoir parameters. Nowadays, it has been widely used in the dynamic monitoring of marine oil and gas reservoirs. It could also be used for monitoring the CO2 injection at CO2 geological storage sites. It can give us a clear image of the injected CO2 in the reservoir. Seismic waveform inversion is a relatively new method for time-lapse monitoring. In this paper, we test the double difference full waveform inversion method on a synthetic 4D seismic data set. The preliminary results show that it is possible to use 4D full waveform inversion method to monitor the velocity changes caused by CO2 injection.
Research on Propagation Characteristics of Seismic Signal for Moving Armoured Targets
Authors: Ding Kai , Zheng Shoujun , Li Xinghua , Rong Yingjiao
Published: February 2021

This paper is focused on the Seismic Signal characteristics of wheel and track vehicles. The effect of vehicle speed of these two vehicles on the Seismic Signal was studied through experimental and theorical methods. The Seismic Signal s of these two vehicles with two different speeds were tested firstly. Then the measured signals were analyzed by means of the power spectrum method and the wavelet transform method, respectively. And the time- and frequency domain features of the signals were obtained subsequently. Finally, the influence of the speed and type of vehicle on the time- and frequency domain features of the signal and its propagation characteristic were investigated. The results show that, with the propagation of vehicle speed and distance, there is a similar varying law of the Seismic Signal for different vehicles. However, the difference of the time- and frequency domain feature between the two vehicles are striking.
Factors influencing microtremor data collected using nested-triangular array configurations
Authors: Chen Gaoxiang , Ge Shuangcheng , Zhao Yonghui , Chen Kanfu , Hu Shufan
Published: February 2021

The availability of microtremor data is potentially affected by various external factors. By combining field data and artificial interference, this work aims to determine the correlation between these factors and the dispersion curve of fundamental-mode Rayleigh waves extracted from microtremors. The first step was to obtain real, high-quality microtremor records using a triangular ten-station array of 48-m radius. Secondly, a series of artificial or semi-artificial interferences of varying type, duration, amplitude, etc., were generated and combined with the real records to imitate actual interferences. Thirdly, all the dispersion curves of the fundamental-mode Rayleigh waves of these modified microtremor records were estimated using the extended spatial autocorrelation method (ESAC). Finally, by comparing the experimental dispersion curves with the original curve, in terms of overlap ratio, we obtained useful conclusions that can be directly applied to microtremor data collection and analysis.
The Short-term Mass Change of Greenland Ice Sheet and the Atmospheric Forcing
Authors: Peng Zhenran , Wang Linsong , Chen Chao
Published: February 2021

In recent decades, the global warming drives the huge ice sheet melting in northern hemisphere. Previous studies on long-term melting rates of Greenland have basically reached agreement, but there is still a lack of the knowledge of the pattern the short-term ice mass change, makes it difficult to fulfill the understanding of the mechanism of the ice sheet. In this study, we used Gravity Recovery and Climate Experiment (GRACE) RL06 data to derive the time series of mass variation of Greenland Ice Sheet (GrIS), from January 2003 to December 2015. We derived the short-term mass change rate during 2003-2015 and found that the GrIS has experienced four melting stages, i.e., a steady melting (-204.4 Gt/yr) phase form 2003 to 2009, an abrupt accelerating (-384.6 Gt/yr) phase form 2010 to 2012, an abnormal pause (+24.8 Gt/yr) year in 2013 and a recovering (-207.3 Gt/yr) phase from 2014 to 2015. In addition, using ensemble empirical mode decomposition (EEMD), the high frequency signal has been removed and the annual mass change has been studied, which shows inter-annual variability. Meanwhile, we correlated the annual mass change with the Greenland Blocking Index (GBI) and North Atlantic Oscillation (NAO) during summertime and the correlation for 2003-2015 was found at r=-0.63 between the summer GBI and the annual mass change, while r=0.57 between summer NAO and the annual mass change. Our results indicate that the short-term mass change of GrIS mainly forced by atmospheric variability.
3-D Regularized focusing migration method for gravity data
Authors: Ding Yidan , Ma Guoqing , Meng Qingfa
Published: February 2021

Potential field migration of gravity data is a kind of method using the migration concept to efficiently obtain the density distributions subsurface. To get migration imaging results with the high resolution, we propose the regularized focusing migration method that adopts the regularization theory to realize focusing migration imaging and the conjugate migration direction method to solve the optimal solution of model parameters, which effectively improves the divergence of the conventional migration imaging. Synthetic model tests demonstrate that the proposed advanced method improves the imaging resolution significantly while guaranteeing the computational efficiency, and can bring about the relatively convergent results in a random Gaussian noise environment. This method is applied to the interpretation of the gravity anomaly from Huayangchuan, Shaanxi Province, which predicts the spatial distribution of uranium deposits.
Deep electrical structure of nailinba polymetallic mine in Balinzuo Banner, Inner Mongolia
Authors: Wang Tianqi , Han Jiangtao , Ma Guoqing , Liu Wenyu , Zhou Zikun , Kang Jianqiang , Guo Zhenyu , Yuan Tianmeng
Published: February 2021

The middle part of the Da hinggan mountains is an important mineral resource base in China. Since the Mesozoic, due to the uplift of the mantle, the extension of the crust, the strong intraplate volcanic eruption and magmatic intrusion, the Mesozoic magmatic tectonic belt has attracted worldwide attention. For further exploring the deep structure of this area, the final geoelectricity structure was established based on a 50-kilometer magnetotelluric sounding profile in this area. Through data acquisition, phase tensor decomposition processing, and nonlinear conjugate gradient inversion, the model reveals the main electrical structural characteristics of this area: 1. The whole has a characteristic of “longitudinal layering and horizontal block”, and the shallow electrical structure is consistent with known geological conditions; 2. There is a distribution inferred that a low-resistance anomaly appears due to the fragmentation of the surface rock layer caused by the uplift of deep intrusive rocks on the surface; 3. There are three more obvious electrical gradient zones or low-resistance anomalies in the deep part, which are presumed to be fault zones or structural erosion variable zone; 4. Three electrical gradient zones in the section divide the deep structure into four large-scale and high-resistance bodies, which reflects the spatial distribution of deep concealed granite, thereby restoring the complex anticline, secondary grade anticline, oblique uplift and depression. In addition, given the electrical structural characteristics and known the mine locations and the field exploration conditions, we conclude that the location of the prospecting target should be on a belt with Shuangjianzishan Pb-Zn-Ag mine, Nailinba Cu-Ag mine, Nailinba Fe mine, and Baiyinnuoer Pb-Zn mine. Moreover, this target is further divided into the middle area of Nailinba Cu-Ag mine and Baiyinnuoer Pb-Zn mine in combination with field surveys.
The application of ground high-precision magnetic survey to the geology and mineral investigation in Huanghe Town area
Authors: Lu Yuguo , Xiong Bin , Wang Yanhe , Su Xiaoqin
Published: February 2021

Three projects have been done to investigate the geology and mineral distribution in Huanghe town area A’nyemaqen-Bayanhar orogen, during the year 2013~2017. Ground high-precision magnetic method on a scale of 1:50000 has been used to study the magnetic character of the geological body and rocks. Correction has been taken in order to normalize magnetic anomaly calculated by different zero points. With the understanding of magnetic character, the distribution of stratum and geological structure can be known. After four years’ job, 16 faults have been recognized and an acid-intermediate intrusive lithosome has been found.
Application of integrated geophysical methods in geothermal exploration: a case in Zhangjiakou
Authors: Zhang Dailei , Yuan Wenzhen , Xing Yifei , Li Yanyan , Lei Xiaodong , Yu Guoming
Published: February 2021

Geothermal energy has become increasingly important in our energy structure as it is a kind of clean and sustainable resource. Zhangjiakou, along with Beijing, is the host city of Winter Olympic Game 2022 and has the demand of geothermal resources. In the central-south part of Zhangjiakou area, integrated geophysical exploration was carried out in 2019, including regional and local high-precision gravity, magnetotelluric (MT), controlled source audio magnetotelluric (CSAMT) and seismic measurement. Combined with geothermal geological survey, new secondary faults, the contour maps of depth of geothermal reservoir and basement are achieved, which plays a vital role in delineating geothermal anomalous area. Based on the analysis of geophysical interpretation results, geological and hydrological information, the geothermal favorable zone and drilling target areas are determined. The work done in the year of 2019 is the beginning and basis of this geothermal resource survey project, and will provide technical support for the drilling work.
Study on the application of comprehensive geophysical prospecting technology for the goaf detection in coal mine
Authors: Chen Fengge , Wang Xuan , Wang Zhihao , Zheng Jianqi
Published: February 2021

Aiming at the problem that drilling technology is time-consuming and challenging to be used to explore the goaf of a coal mine, a comprehensive geophysical exploration technology is proposed to quickly delineate the goaf. Through the layout of the TEM survey line to survey the development characteristics of goaf in the work area, and then with the help of magnetotelluric sounding method to verify the goaf delineated by TEM, the abnormal area of apparent resistivity obtained by the two methods were basically consistent. And it is consistent with the mining data of coal face. Based on the comprehensive geophysical exploration technology, the problem of multiple solutions of a single geophysical exploration method is solved, which provides technical support for the exploration of goaf in similar projects in this area in the future.
Analysis on the predicting significance of mid-strong earthquake swarms in Gansu and its surrounding areas
Authors: Dou Xiying , Wang Enli , Zhang Hui , Zhang Bo , Zhang Liqiong , Jiang Jiajia
Published: February 2021

In order to obtain the accurate prediction efficiency of earthquake swarms in Gansu province, the statistics of minor-moderate earthquake swarms that have occurred in Gansu since 1980 are performed. The earthquake swarm parameters are calculated and the precursory earthquake swarms are extracted based on the criteria of distinguishing the abnormal earthquake swarm. The precursory swarms obtained were analyzed correspondingly with the earthquakes with M≥5 in and around Gansu, and the prediction efficiency of them was evaluated. The accurate precursor index of the earthquake swarms in Gansu were summarized, which provided a judging basis for the seismic trending and made a certain contribution to earthquake prevention and disaster reduction.
Mann-Kendall Mutation Analysis of Temporal Variation of Apparent Stress in Qinba Mountains and Its Adjacent Areas
Authors: Wang Weidong , Yi Zheng , Chen Dou
Published: February 2021

In this abstract, we use the Mann-Kendall Mutation analysis to determine the source parameters of 125 earthquakes in the Qinba Mountains and its neighboring areas between 1997 and 2013. Seismic moments, apparent stress, and seismic radiant energy of the earthquakes were calculated. The Mann-Kendall mutation test was used to analyze the temporal data of the apparent stress. The results indicate that there occurred three downward mutation points in apparent stress in June 1998, October 1998 and March 1999, and then only one earthquake, Wudu 4.5earthquake with magnitude greater than 4 occurred in this area till September 2001. The average apparent stress decreases from 0.16 MPa from July 1997 to March 1999 to 0.15 MPa from April 1999 to September 2001. After the rising mutation point in apparent stress in October 2001, the average apparent stress increases from 0.15 MPa from April 1999 to September 2001 to 0.18 MPa from October 2001 to December 2013. A series of moderate to strong earthquakes with ML4.9, ML6.0, ML5.9, and ML5.2 then occurred in April 2003, May 2008, July 2008 and September 2009. The results demonstrate that the Mann-Kendall mutation analysis can fairly reflect the trend of apparent seismic stress, which is helpful for seismic activity prediction.
Ground penetrating radar exploration at archaeological site in Shi Village, Xia County, Shanxi Province
Authors: Wang Zhuo , Zeng Zhaofa , Zhang Ling
Published: February 2021

With the rapid development of city construction, it’s necessary to make archaeological exploration process more convenient, efficient and undamaged. As a result, some geophysical methods begin to be used firstly to find anomaly roughly during exploration. Ground penetrating radar (GPR), as a non-destructive and high-resolution method, should be an effective method in relatively shallow archaeological exploration. To verify the effectiveness of GPR, this paper mainly discusses the application of a combining method of GPR and Luoyang Spade – a traditional archaeological method at pre-Qin period site in Shi Village, Xia County, Yuncheng City, Shanxi Province, used GPR to find the anomaly area, then used Luoyang Spade to excavate to verify. This method can greatly shorten exploration time and reduce damage of culture relics.
A fast forward algorithm for three-dimensional gravity gradient tensor using the compact difference schemes
Authors: Hu Shuanggui , Pan Kejia , Tang Jingtian
Published: February 2021

We propose a fast and accurate 3D large-scale forward modeling method to compute the gravity gradient tensor, in terms of a fourth-order compact finite difference scheme and the extrapolation cascadic multigrid (EXCMG) method. Firstly, the 19-point fourth-order compact finite difference scheme with unequal mesh sizes in different coordinate directions is used to discretize the governing 3D Poisson equation. The resulted symmetric positive definite linear systems are solved by the EXCMG method. Then, the second-order derivatives (gravity gradient tensor) are calculated by solving a series of tridiagonal linear systems resulting from the fourth-order compact finite difference discretization. Finally, numerical result for a cubic model with positive density is used to verify the accuracy of our presented method. It shows that our method can give nearly fourth-order accurate approximations to gravitational potential and gravity gradient tensor. The accuracy is much higher and more efficient than traditional finite difference methods.
Application of airborne electromagnetic method in the exploration of Qingchengzi mine in Liaoning Province, China
Authors: Fu Changmin , Di Qingyun , lei Da
Published: February 2021

Qingchengzi area of Liaoning Province is an important concentration of polymetallic minerals in China. But with the long-term mining, Qingchengzi mining area has become a crisis mine, and the prospecting and prediction in the mining area has become a key work. The resistivity data is closely related to the existence of minerals. We carried out the VTEM airborne electromagnetic observation in this area. The primary processing results show that the inversion result is very consistent with the existing geological information. The processing results of airborne electromagnetic data will provide an important guarantee for the electrical structure, fault distribution and structural framework in the ore concentration area, as well as the delineation of the mineral target area.
Investigation and Analysis of Airborne Gamma Radiation Absorbed Dose Rate of Danjiangkou Reservoir
Authors: Li Yichuan , Yu Junchuan , Yu Xuezhong , Mi Yaohui , Hao Jingyan , Li Jiaojiao
Published: February 2021

Airborne gamma-ray spectrometry is widely used in regional nuclear radiation surveys and environmental nuclear radiation pollution assessments. This paper aims at analyzing the status of nuclear radiation in the Danjiangkou Reservoir area by using airborne gamma spectrometry data. Mapping of the gamma radiation air absorbed dose rate in the study area was completed by using the Beck formula and divided into three different grades according to relevant national standards. Basing on the survey results, the main sources of high radioactive anomalies in the Danjiangkou Reservoir and surrounding areas were identified. Furthermore, a protection proposal was put forward to guarantee the water quality and safety of residents in the South-to-North Water Diversion Source.