Monitoring lime and cement improvement using spectral induced polarization and bender element techniques

Spectral induced polarization(SIP)and bender element(BE)techniques show a high sensitivity to particle size,particle distribution and content of generated hydration products,which essentially govern the efficiency of ground improvement.In this context,both SIP and BE were integrated on a column setup to monitor the processes of lime and cement stabilization.A 5 mmol/L Na2CO3 solution was injected into the sand-lime mixture to produce CaCO3 precipitation,while deionized water was injected into the sandcement mixture to induce the hydration of cement.The average diameters of the precipitated particles or clusters were calculated from the relaxation time,which was a significant parameter of SIP signals,via the Schwarz equation.Two pairs of BE were used to demonstrate the heterogeneity of the product precipitation,which was probably caused by the location of the inflow and outflow on the SIP-BE column.SIP and BE showed the capability of nondestructively monitoring the spatiotemporal chemical evolution processes,which could be helpful for engineering applications.

Some Experiences of Resistivity and Induced Polarization Methods on the Exploration of Sulfide: A Review

Sulfide minerals are a group of compounds with the presence of sulfur. This group’s most abundant and economically members are pyrites, pyrrhotite, chalcocite, galena, sphalerite, and the group of copper sulfides minerals. Resistivity and Induced Polarization (IP) methods, which play an essential role in mineral exploration, showed great success in sulfide exploration. This paper started on reviewing sulfide formation by giving details which help to understand their genesis better. To make the reader understand the procedures and appropriate mineral exploration methods, we have briefly covered the theory, the basic principles of resistivity and IP methods, and different investigation techniques using one, two, and three-dimensional surveys. Based on many electrical surveys, we discussed with examples of resistivity and IP methods applied to the exploration of sulfide deposits: the data inversion and interpretation of the geophysical signatures of most of the sulfide deposits in various geological environments were analyzed and end by showing both successful surveys and limitations of the methods.

Study on multiple induced polarization parameters in groundwater exploration in Bashang poverty alleviation area of Heibei Province,China

The study examines a water exploration and poverty alleviation project in Guyuan county.The study analyzes correlations between aquifers and multiple induced polarization(IP)parameters,including resistivity,polarizability,deviation,half decay time,water-bearing factors,and Kc,a new parameter refined in this study.Based on the study,the well was placed accurately,and its maximum water inflow reached 30 m3/h.Kc value highlights the rate of change at early stages of IP secondary field.Kc value served as a quick indicator in this groundwater prospecting and is validated in practice.Progress has been made in finding new parameters in exploring water with IP method.Thanks to the project,local people have access to water and poverty alleviation has scored some achievements.

Laser Intensity Variation in Amplitude and Phase Induced by Elliptically Polarized Feedback

The laser output characteristics under elliptically polarized optical feedback effect are studied. Elliptically polarized light is generated by wave plate placed in the feedback cavity. By analyzing the amplitude and phase of the laser output in the orthogonal direction, some new phenomena are firstly discovered and explained theoretically.Elliptically polarized feedback light is amplified in the gain medium in the resonator, and the direction perpendicular to the original polarization direction is easiest to oscillate. The laser intensity variation in amplitude and phase are related to the amplified mode and the anisotropy of external cavity. The theoretical analysis and experimental results agree well. Because the output characteristic of the laser has a relationship with the anisotropy of the external cavity, the phenomenon also provides a method for measuring birefringence.

Determination of rock mass integrity coefficient using a non-invasive geophysical approach

Determination of rock mechanical parameters is the most important step in rock mass quality evaluation and has significant impacts on geotechnical engineering practice.Rock mass integrity coefficient(KV)is one of the most efficient parameters,which is conventionally determined from boreholes.Such approaches,however,are time-consuming and expensive,offer low data coverage of point measurements,require heavy equipment,and are hardly conducted in steep topographic sites.Hence,borehole approaches cannot assess the subsurface thoroughly for rock mass quality evaluation.Alternatively,use of geophysical methods is non-invasive,rapid and economical.The proposed geophysical approach makes useful empirical correlation between geophysical and geotechnical parameters.We evaluated the rock mass quality via integration between KV measured from the limited boreholes and inverted resistivity obtained from electrical resistivity tomography(ERT).The borehole-ERT correlation provided KV along various geophysical profiles for more detailed 2D/3D(two-/three-dimensional)mapping of rock mass quality.The subsurface was thoroughly evaluated for rock masses with different engineering qualities,including highly weathered rock,semi-weathered rock,and fresh rock.Furthermore,ERT was integrated with induced polarization(IP)to resolve the uncertainty caused by water/clay content.Our results show that the proposed method,compared with the conventional approaches,can reduce the ambiguities caused by inadequate data,and give more accurate insights into the subsurface for rock mass quality evaluation.

Reconnaissance Geophysical Study on the Southeastern Part of Al-Qashah Aera, KSA

The investigated study area locates about 72 km from Jeddah City, Makkah District, Kingdom of Saudi Arabia. The study mainly aimed to define the most significant zones of possible mineralization and outline their subsurface parameters (location and strike) in the southeast of Jabal Al-Qashah. Several geophysical methods have been conducted to carry out the goal, including ground magnetic, self-potential (SP), and induced polarization (IP) methods. Integrating these methods aims to help delineate the possible mineralization in the study area. The magnetic survey was conducted along 17 profiles where these profiles were chosen to be perpendicular to the strike of the quartz shear zone. Self-potential was applied along with five profiles covering the study area. At the same time, induced polarization was used along with one profile located at the western side of the study area corresponding to some magnetic and SP profiles. The most interesting zones of mineralization were successfully determined by comparing the results of residual magnetic profile (3), SP profile (1), and IP profile, where geological structures control some mineralization.

Inversion of time-domain airborne EM data with IP effect based on Pearson correlation constraints

Due to the induced polarization(IP)eff ect,the sign reversal often occurs in timedomain airborne electromagnetic(AEM)data.The inversions that do not consider IP eff ect cannot recover the true umderground electrical structures.In view of the fact that there are many parameters of airborne induced polarization data in time domain,and the sensitivity diff erence between parameters is large,which brings challenges to the stability and accuracy of the inversion.In this paper,we propose an inversion mehtod for time-domain AEM data with IP effect based on the Pearson correlation constraints.This method uses the Pearson correlation coeffi cient in statistics to characterize the correlation between the resistivity and the chargeability and constructs the Pearson correlation constraints for inverting the objective function to reduce the non uniqueness of inversion.To verify the eff ectiveness of this method,we perform both Occam’s inversion and Pearson correlation constrained inversion on the synthetic data.The experiments show that the Pearson correlation constrained inverison is more accurate and stable than the Occam’s inversion.Finally,we carried out the inversion to a survey dataset with and without IP eff ect.The results show that the data misfit and the continuity of the inverted section are greatly improved when the IP eff ect is considered.

Ground Electromagnetic and Electric Studies for Um Salim Gold Mine, Central Eastern Desert, Egypt

Horizontal Loop Electromagnetic (HLEM) and Induced Polarization (IP) methods have been carried out within Um Salim gold mine area. The study area reveals special importance, as it comprises rock units, which show some indication of the presence of various mineralization. The result of HLEM has shown significant and well-defined conductive zones are recorded along with the four used frequencies (110 Hz, 440 Hz, 1760 Hz, and 7040 Hz) at the station 2,782,900 and station 2,782,880 of two (HLEM) profiles (596,050 N & 596,240 N) respectively, that may reflect the sources of the conductive bodies are situated at shallow depths continued to considerable depths. The result of IP exhibits a strong anomalous zone centered at stations 140 and 240, with chargeability values ranging (37 to more than 120 mV/V) on chargeability model section, and corresponding to high resistivity on resistivity model section which may reflect considerable surface and subsurface disseminated mineralization. Through the integration between HLEM and IP a core drilling is recommended at station 140 on IP profile which coincides with station 2,782,850 on HLEM profile (596,240 N) to a depth of concerning 100m take a look at the thickness, depth, and grade of mineralization.

Progress on direct assembly approach for in situ fabrication of electrodes of reversible solid oxide cells

Reversible solid oxide cells(SOCs)are very efficient and clean for storage and regeneration of renewable electrical energy by switching between electrolysis and fuel cell modes.One of the most critical factors governing the efficiency and durability of SOCs technology is the stability of the interface between oxygen electrode and electrolyte,which is conventionally formed by sintering at a high temperature of~1000–1250℃,and which suffers from delamination problem,particularly for reversibly operated SOCs.On the other hand,our recent studies have shown that the electrode/electrolyte interface can be in situ formed by a direct assembly approach under the electrochemical polarization conditions at 800℃and lower.The direct assembly approach provides opportunities for significantly simplifying the cell fabrication procedures without the doped ceria barrier layer,enabling the utilization of a variety of high-performance oxygen electrode materials on barrier layer–free yttria-stabilized zirconia(YSZ)electrolyte.Most importantly,the in situ polarization induced interface shows a promising potential as highly active and durable interface for reversible SOCs.The objective of this progress report is to take an overview of the origin and research progress of in situ fabrication of oxygen electrodes based on the direct assembly approach.The prospect of direct assembly approach in the development of effective SOCs and in the fundamental studies of electrode/electrolyte interface reactions is discussed.

The kinetic magnetoelectric effect in laterally boundary-confined ballistic two-dimensional hole gases

A theoretical investigation is presented on the characteristics of the kinetic magnetoelectric effect in laterally boundary-confined ballistic two-dimensional hole gases. It was shown that, though the momentum-dependent effective magnetic fields felt by charge carriers due to the spin-orbit interaction are in-plane orientated in such systems, both in-plane polarized and normal polarized nonequilibrium spin polarization densities could be electrically induced by the kinetic magnetoelectric effect, and the induced nonequilibrium spin polarizations exhibit some interesting characteristics. The characteristics we found indicate that there may be some possible relation between this effect and some recent experimental findings.

Chemically induced dynamic electron polarization investigation of the triplet-radical system in the solution of the triplet quencher

The chemically induced dynamic electron polarization (CIDEP) of the triplet molecule/triplet quencher/2, 2, 6, 6-tetramethyl-1-piperidinyloxyl (TEMPO) systems were measured using the high time-resolved ESR spectrometer. The competition between the radical-triplet pair mechanism (RTPM) and triplet mechanism (TM) or radical pair mechanism (KIM) polarization in the solution of the triplet quencher was investigated, and the relationships between reaction rate of the radical-triplet pair and quenching rate of triplet was deduced.

Study on the Coincident-Loop Transient Electromagnetic Method in Seafloor Exploration——Taking Jiaodong Polymetallic Mine as a Model

The transient electromagnetic(TEM)method becomes more urgent than ever for marine ex-ploration due to abundant resource reserves and the increasing undersea engineering construction activities,especially in the offshore exploration of mineral deposits such as Sanshandao gold mine.However,the re-search and application of TEM method in marine environment are still challenged by many problems.Such contradiction motivates our study on the coincident-loop TEM in seafloor exploration.The TEM response of coincident loops is firstly derived in the integral form,based on the potential functions in Helmholtz equ-ations for a magnetic source locating in the whole-space layered model.The frequency-domain vertical magnetic field is described as the Hankel integral with double first-order Bessel functions of first kind.Se-condly,the time-domain induced voltage is obtained by transforming the frequency-domain response through the cosine transform and then taking the derivative of time.To simultaneously solve the Hankel transform and the cosine transform,a novel algorithm is introduced by adapting the fixed-point quadra-ture and extrapolation via the Shanks transformation.Finally,a typical conductivity model for marine po-lymetallic deposit is designed to investigate the characteristic of TEM response under various conditions.Numerical results demonstrate that existence of conductive seawater causes the TEM response to increase significantly and decay slower.The air-sea reflected electromagnetic waves lead to a significantly large fake negative response(NR)in shallower seawater with depth less than 300 m.Increase in the height of loops will weaken and delay the anomaly response and shorten the observation time-window.The height of configu-ration should be no more than 100 m for shallower targets and 50 m for deeper targets,respectively.The observation time-window should cover 10-1000 ms.Increase in the radius of loops only enhances the TEM response proportionally but hardly improves the relative anomaly.The vertical resolution on the low-resistivity target approximates 20 m for the configuration considered in the study.Decreases in D.C.resistivity and chargeability cause the positive response(PR)to increase significantly and decay more ra-pidly.Meanwhile,the NR is advanced and enlarged significantly and decays slower compared with the PR.The influence of time constant is not monotony and there exists an optimal value for producing the maxi-mum NR.As the frequency parameter increases,the PR is caused to decay more rapidly without magni-tude change and the NR is advanced and decays more rapidly with significant increase in magnitude.The influence of frequency parameter is more pronounced than that of time constant.

Sequential and Simultaneous Joint Inversion of Resistivity and IP Sounding Data Using Particle Swarm Optimization

In order to interpret the vertical electrical sounding data more reliably and effectively in the case of lacking proper priori information, two inverse schemes are proposed to invert combined re- sistivity and induced polarization data by using particle swarm optimization technique. Based on the computational formula of induced polarization, the inversion for chargeability/polarizability data can be transformed into inverting equivalent resistivity data. Then, the inversion for combined data can be decomposed into two procedures： inverting resistivity data and inverting equivalent resistivity data. A sequential inversion scheme is presented to run the two procedures sequentially. Contrast to the se- quential scheme, a simultaneous one is proposed to invert resistivity and induced polarization data si- multaneously. Both the sequential and simultaneous schemes are performed via centered-progressive particle swarm optimization algorithm for more exploratory purpose. Numerical experiments show that both the designed inversion algorithms can invert resistivity and induced polarization data suc- cessfully with fast convergence and high accuracy, even performed in a large search space. The inverse results are comparable to the results from generalized linear method. As an approximate importance sampler, the particle swarm optimization based algorithm can provide posterior analysis conveniently. We employ the posterior probability distributions of inverted model parameters to evaluate the per- formance and uncertainty of inversion. The posterior analysis and further field data testing show that the proposed inversion algorithms perform good sampling of the equivalence region and make sure that the global optimum can locate in the high probability areas.