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[en] In this paper, I suggest the use of combined inversion for three- and four-electrode array data. Two-dimensional (2D) inversion results calculated using Wenner (W), Schlumberger (S), Dipol–Dipol (DD), left- and right-side pole–dipole (PD-L and PD-R), synthetic data and their combined inversion results were compared with respect to the resolution and accuracy of the inverted models. This comparison showed that the combined inversion of data from any two sets of arrays (e.g. W + S, W + DD, PD-L + DD) gave better resolution than the individual inversion of data from each array compared with the real model. However, inversion of the PD-L, PD-R and DD data sets jointly gave a better result than the single use of any electrode array and the combined inversion of any two electrode arrays. Furthermore, model resolution matrices obtained for all individual and combined data inversions showed that the combined data set inversion can recover the block resistivities at both the beginning and the end of the profile. Field data inversions also support the synthetic data inversion result
[en] In this paper, Master/Slave station structure, conventional high-stable CAN-bus and RS485 bus are used to construct the data collecting net of three-dimention DC resistivity system with the emphasis on the selection of communication method and the construction of communication net. After deciding the measurement style of electrodes grid, analysis of the communication net and the calculation of collecting time was performed, and it was concluded that the Master/Slave station structure can reach the communication requirement for three-dimention DC resistivity survey, which is helpful to the design of electrodes communication for future blind deposit prospecting. (authors)
[en] Geophysical investigation was carried out at the proposed laboratory construction site at Bukit Besi, Universiti Pertahanan Nasional Malaysia (UPNM) upon the request by the Jabatan Kerjaraya Malaysia (JKR). The objective of the investigation is to delineate granite bedrock topography which was found fluctuate through drilling causing the engineers and the architects have to design a new proposal for the building plan. This may increased the costing of the overall project. The original proposal building plan suggested the foundation of the building is at 20 m below surface. However, data from drilling shows the bedrock was found at 23 m at BH3 and 12 m depth at BH4. In order to reach the level required from the building proposal plan, at least 10 m of rock have to be removed from the site, in addition to the 10 m thickness of top soil. Two geophysical methods were proposed; Seismic Refraction and Resistivity Imaging. The result from seismic survey is shown in a two dimensional profile, plotting the depth of seismic velocity (m/s) traveling in the media against the horizontal distance (m). The velocity of seismic wave travelled in the subsurface can be divided into three ranges; <1500 m/s is a soil layer 1500 - 2000 m/s is a semi weathered and >2000 m/s is a hard layer. Additionally, it can be assume the depth of the fresh granite ranging from 0 m to 23 m from ground surface. On the other hand, the resistivity survey gives the information on resistivity of the subsurface materials and also plotted in a 2D profile. The resistivities value ranges between 50 - 10000 Ωm and can be divided into three classes; <1000 Ωm, 1000 - 3000 Ωm and >3000 Ωm. The thickness of the overburden layer ranges between 0 - 20 m, as represented by a low resistivity value, which also appear at deeper layer. This expected due to the present of fractured within the granite body which is filled by clay mineral or water. As a conclusion, the investigation found the granite body's topography is in an irregular form. Correlation with the drilling data shows an agreement with the results from both seismic refraction and resistivity surveys. (author)
[en] This work suggests a method to evaluate quantitatively the effect of doping oxide on the microstructure phase coexistence, mobility of charge carriers of non-polarized ceramic PZT doping by different amounts of Fe2O3 and Cr2O3. Besides the analysis of XRD patterns, the electrical properties measurement showed that chromium and iron oxide doping furthers the tetragonal structural phase and disadvantages the rhombohedral structure to a cubic form. Besides, chromium oxide causes more rapidly a mobility of charge carriers of the non-polarized material, compared to iron oxide. Furthermore, the addition of both chromium and iron oxides promotes increase in the size of the tetragonal phase crystal. On the other hand, the rhombohedral phase crystal size increases due to the addition of iron oxide and decreases by doping with chromium oxide.
[es]Este trabajo sugiere un método para evaluar de manera cuantitativa el efecto del óxido impurificado sobre la coexistencia de fase de la microestructura, la movilidad de los portadores de carga de impurificación de PZT cerámico no polarizado por diferentes cantidades de Fe2O3 y Cr2O3. Además del análisis de los patrones XRD, la medición de las propiedades eléctricas mostró que la impurificación con óxido de cromo y óxido de hierro fomenta la fase estructural tetragonal y desfavorece a la estructura romboédrica por una forma cúbica. Además, el óxido de cromo genera una movilidad más rápida de los portadores de carga del material no polarizado en comparación con el óxido de hierro. Además, la adición de óxido de cromo y óxido de hierro promueve el aumento de tamaño del cristal de fase tetragonal. Asimismo, el tamaño del cristal de la fase romboédrica aumenta debido a la adición de óxido de hierro y disminuye por la impurificación con óxido de cromo.
[en] The normal state resistivity of single phase polycrystalline Gd(Ba2-x Prx)Cu3 O7+δ samples with 0.00≤x≥0.50 have been investigated. The two dimensional variable range hopping is dominant in the normal state resistivity of the samples. The localization length, hopping range, and hopping energy of carriers show that Pr doping strongly localizes the carriers in normal state, and finally causes the suppression of superconductivity
[en] One major factor in the design of earth electrodes is the soil resistivity. This paper is based on experience obtained at sites with high soil resistivity variations. Many test measurements have been made to study the effect of horizontal variations in soil resistivity at several selected locations at Inshas area. The method is also applicable to soils with arbitrary soil resistivity variations with depth.With such variations in the measured values, the question then arises as to the correct value to be taken for the design . The paper presents a methodology for the statistical estimation of soil resistivity from any test data and computation of error bounds of the estimates in statistical terms. Actual test field measurements of soil resistivity have been used as an application. The bounds shown indicate the wide variability of soil resistivity
[en] Basic principles of high-density resistivity method, the instrument and equipment used by this method, and the application effect of this method to in-advance exploration of Furongshan tunnel in Shaoguan city are introduced in this paper. Characteristics of apparent resistivity distribution in structurally fractured zones, old underground workings and karst caves are summarized. Based on the above-mentioned 7 structurally fractured zones, 7 old underground workings and 3 karst caves have been interpreted. Practice proves that interpretation results of resistivity data are in good coincidence with drilling and underground workings materials. Finally, feature and application potential of the method is analyzed. (author)
[en] In this study, I assumed the underground consist of horizontal layers. I developed one-dimensional (1D) Direct Current Resistivity (DCR) and seismic refraction inversion code using MATLAB package and attempt to find velocity, resistivity and depth of the layers. The code uses damped least square technique. The code can do inversion on DCR and seismic data either individually or jointly. I tested the joint inversion code on synthetic data. Eventually, I saw that the result of joint inversion is better than the result of individual inversions. The joint inversion found depth of models of each layer and, in addition, velocity and resistivity closer to real values
[en] The association between a precursory geomagnetic anomaly and a Vrancea earthquake of moderate-to-high magnitude (MW = 6.3) followed by weaker earthquakes (MW < 5) was first proved in this paper. This finding extended to a broader magnitude range 3.7 ≤ MW ≤ 6.3 the conclusion of our earlier papers, i.e., that the great majority of Vrancea earthquakes of magnitudes 3.7 ≤ MW ≤5.0 were accompanied by observable precursory electromagnetic anomalies. Our works show that neither the precursor time nor the amplitude of the precursory magnetic anomaly can be linked reliably with the magnitude of the anticipated earthquake. Knowing the way electric resistivity varies ahead of an earthquake, we can assert that the earthquake-precursory growth in geomagnetic impedance is matched by an earthquake-precursory decrease of electric resistivity. (authors)
[en] Geo electrical resistivity survey was conducted in the Bukit Tenggek, Setiu, Terengganu to detect the possible existence of an ancient tunnel which is believed to be in the area. Geo electrical resistivity method was found very effective in searching for archaeological exploration and underground structures (tunnels and artifacts). Geo electrical resistivity survey was carried out using Terrameter ABEM SAS1000 and Wenner array electrode configuration. The survey area is located in a damp valley with a stream across the region. 2-D resistivity image showed the existence of anomalies in several areas that can be associated with the structure. Low resistivity value represents the estimated existence of the old tunnel, while isolated rounded anomalies are believed to be associated with barrels/artifacts. 3-D resistivity profiles, shows anomalies that may be caused by the existence of a horizontal and two vertical tunnels (shaft). However, the drillings work need to be done to figure out the exact cause of these anomalies. (author)