Application of Electrical Resistivity and Chargeability Data on a GIS Platform in Delineating Auriferous Structures in a Deeply Weathered Lateritic Terrain, Eastern Cameroon

Exploration for primary gold in tropical settings is often problematic because of deep weathering and the development of a thick soil cover. In this paper we present the results of both chargeability and resistivity surveys carried out over the Belikombone hill gold prospect (14?00' - 14?25'E, 5?25' - 6?00'N) in the Betare Oya area (eastern Cameroon), where previous soil sampling had identified gold anomalies. The geophysical data were obtained using Syscal Junior 48 resistivity meter and the Schlumberger configuration array for both the vertical electrical soundings (VES) and horizontal profiling. These data were further built into a GIS framework and the continuity of favourable gold-bearing structures at depth modeled using WINSEV, RED2INV and SURFER extensions softwares. IP (Induced Polarization)-chargeability and resistivity data combined, have identified irregular anomalous zones trending NE-SW. This trend is consistent with the attitude of most auriferous quartz veins exposed in artisanal pits and parallel to the regional shear zone system and foliations. The high resistivity anomalies correspond to quartz veins while the relatively high IP anomalies correspond to low sulphide ± gold concentrations in the quartz veins. Modeling IP-chargeability and resistivity data prepared as contours and 3D maps, culminated to the development of an inferred, irregular and discontinuous mineralized body at depths of up to 95 m. The size and shape of this mineralized body can only later be tested by drilling to ascertain the resource.

Influence of shallow low resistivity thin layer on SATEM response at different receiving heights in near and far regions

In recent years,the semi-airborne transient electromagnetic method(SATEM)has been rapidly developed in China.Based on the theoretical development of the long grounding wire source transient electromagnetic method,the unmanned aerial vehicle is equipped with the receiving coil to collect the electromagnetic response data at high altitude,making the TEM no longer affected by the terrain and greatly improving the actual working efficiency.However,its flight altitude has not been concerned for a long time.It is generally believed that the change of flight altitude only affects the amplitude of the received response.However,under special circumstances,the electromagnetic response data received at different flight altitudes in the near and far regions may lose the characteristic information of the target geological body.This paper simulates the low resistance thin layer model and analyzes the electromagnetic responses of different receiving heights under different transceiver distances.The results show that in the near area,when the flight altitude is higher than 30 meters or more,the received electromagnetic response will lose the information of the shallow lowresistance thin layer,while in the far area,the change of flight altitude has no obvious influence on the characteristic electromagnetic response information of the received geological body.

Coupling Effects on Gold Mineralization of Deep and Shallow Structures in the Northwestern Jiaodong Peninsula, Eastern China

For understanding the possible deep-seated processes and geodynamic constrains on gold mineralization, comprehensive physicochemical and geochemical studies of gold mineralization have been undertaken within the paleo-lithosphere framework during the metailogenic epoch from the northwestern part of the Jiaodong Peninsula in this paper. A general image of the paleo-crust has been remained although it has been superimposed and reformed by post-metailogenic tectonic movements. The gold ore deposits occur usually in local uplifts and gradient belts featuring a turn from steep to gentle in granite-metamorphic contact zones, relative uplifts of gradient zones of the Curier isothermal interfaces, depressions of the Moho discontinuity and areas where depth contours are cut by isotherms perpendicularly. Gold mineralization and lithogenesis are characterized by high temperature, low pressure and high strength of thermal flux. The depth of mineralization ranges from 0.8 to 4.5 km. The depth of the top interface of the granitic complex in the metallogenic epoch is about 3 km. There is a low-velocity layer （LVL） at the bottom of the upper crust with a depth close to 19.5 km, which may be a detachment belt in the crust. The appearance of the LVL indicates the existence of paleo-hyperthermal fluid or relics of molten magma chambers, which reflects partial melting within the crust during the diagenetic and metallogenic epochs and the superposition effects of strike-slip shearing of the Taulu fault zone. The subsidence of the Moho is probably attributed to the coupling process of the NW-SE continental collision between North China and the Yangtze Block and the strike-slip movement of the Tanlu fault accompanied with underplating of mantle magma in the northwestern part of the Jiaodong Peninsula. The underplating of mantle magma may result in partial melting and make granite magma transfer upwards. This is favorable for the migration of metallogenic materials from deep to shallow to be enriched to form deposits. Coupling interactions between the strike-slip of the Taulu fault, the underplating of mantle magma, partial melting within the crust, and hyperthermal fluid, etc. may be the important factors controlling the gold mineralization and spatial structures in the metailogenic system.

Crust and Upper Mantle Electrical Resistivity Structure in the Panxi Region of the Eastern Tibetan Plateau and Its Significance

The Panxi region is located in the frontal zone of positive squeezing subduction and side squeezing shearing between the Indian plate and the Eurasian plate. The long-period magnetotelluric （LMT） and broadband magnetotelluric （MT） techniques are both used to study the deep electrical conductivity structure in this region; magnetic and gravity surveys are also performed along the profile. According to the 2-D resistivity model along the Yanyuan-Yongshan profile, a high- conductivity layer （HCL） exists widely in the crust, and a high-resistivity block （HRB） exists widely in the upper mantle in general, as seen by the fact that a large HCL exists from the western Jinpingshan tectonic zone to the eastern Mabian tectonic zone in the crust, while the HRB found in the Panxi tectonic zone is of abnormally high resistivity in that background compared to both sides of Panxi tectonic zone. In addition, the gravity and magnetic field anomalies are of high value. Combined with geological data, the results indicate that there probably exists basic or ultrabasic rock with a large thickness in the lithosphere in the Panxi axial region, which indicates that fracture activity once occurred in the lithosphere. As a result, we can infer that the high-resistivity zone in the Panxi lithosphere is the eruption channel for Permian Emeishan basalt and the accumulation channel for basic and ultrabasic rock. The seismic sources along the profile are counted according to seismic record data. The results indicate that the most violent earthquake sources are located at the binding site of the HRB and the HCL, where the tectonic activity zone is generally acknowledged to be; however, the earthquakes occurring in the HCL are not so violent, which reflects the fact that the HCL is a plastic layer, and the fracture threshold of a plastic layer is low generally, making high stress difficult to accumulate but easy to release in the layer. As a result, a higher number of smaller earthquakes occurred in the HCL at Daliangshan tectonic zone, and violent earthquakes occurred at the binding site of high- and low-resistivity blocks at the Panxi tectonic zone.

Hydrodynamic Links between Shallow and Deep Mineralization Systems and Implications for Deep Mineral Exploration

Deep mineral exploration is increasingly important for finding new mineral resources but there are many uncertainties.Understanding the factors controlling the localization of mineralization at depth can reduce the risk in deep mineral exploration.One of the relatively poorly constrained but important factors is the hydrodynamics of mineralization.This paper reviews the principles of hydrodynamics of mineralization,especially the nature of relationships between mineralization and structures,and their applications to various types of mineralization systems in the context of hydrodynamic linkage between shallow and deep parts of the systems.Three categories of mineralization systems were examined,i.e.,magmatic-hydrothermal systems,structurally controlled hydrothermal systems with uncertain fluid sources,and hydrothermal systems associated with sedimentary basins.The implications for deep mineral exploration,including potentials for new mineral resources at depth,favorable locations for mineralization,as well as uncertainties,are discussed.

Prediction of the Charpy V-notch impact energy of low carbon steel using a shallow neural network and deep learning

The impact energy prediction model of low carbon steel was investigated based on industrial data. A three-layer neural network, extreme learning machine, and deep neural network were compared with different activation functions, structure parameters, and training functions. Bayesian optimization was used to determine the optimal hyper-parameters of the deep neural network. The model with the best performance was applied to investigate the importance of process parameter variables on the impact energy of low carbon steel. The results show that the deep neural network obtains better prediction results than those of a shallow neural network because of the multiple hidden layers improving the learning ability of the model. Among the models, the Bayesian optimization deep neural network achieves the highest correlation coefficient of 0.9536, the lowest mean absolute relative error of 0.0843, and the lowest root mean square error of 17.34 J for predicting the impact energy of low carbon steel. Among the variables, the main factors affecting the impact energy of low carbon steel with a final thickness of7.5 mm are the thickness of the original slab, the thickness of intermediate slab, and the rough rolling exit temperature from the specific hot rolling production line.

Study on coupling between deep and shallow structures of Xingtai area and some significant questions

In the light of results from study on coupling between deep and shallow structures in Xingtai earthquake area during the 'Ninth Five-Year Plan' period and other previous results from deep seismic refraction/reflection and seismic prospecting of petroleum, we infer that there exist a series of shallow faults in the upper crust above the 8 km-deep detachment surface in Xingtai macroseismic focal region, where none of the faults, including Aixinzhuang fault reaches the Quaternary stratum, except that the Xinhe fault cuts through the mid-Pleistocene formation upwards. Aixinzhuang fault and other faults extend downwards into Xinhe fault whereas the Xinhe listric fault stretches downwards at a low dip angle into the detachment surface. The abyssal fault with high dip angle under the detachment surface cutting through the middle and lower crust to Moho is the causative fault for the large Xingtai earthquake, whose dislocation can cause strong earthquakes, shallow fault activity and the motion of surface material. The shallow faults in the upper crust are not causative faults for strong earthquakes, although they may be active faults. The existence of the detachment surface brings about a special relationship between shallow and deep structures, i.e. they are relatively independent of each other and have effects on each other It not only transmits partial energy and deformation between the upper and lower crust,but also has a certain decoupling effect. Finally we conclude that active faults do not necessarily reach the latest stratum, and the age of uppermost faulted stratum cannot represent the latest active period of the fault. This put to us a significant question in regard to the age determination and study of active faults. Other noticeable questions are also inferred to in this study.

Roof structure theory and support resistance determination of longwall face in shallow seam

This paper presents the structure models founded in shallow seam, the roof asymmetry arch with three articulations in roof first weighting and the step voussoir beam in roof periodic weighting. These structure models are differ from classic theory, it establishes the new roof control theory of instability structure roof, especially in shallow seam. Based on the new roof structure theory, the support working state of "given sliding load" is put forward, and the factor of load transmitting is introduced to determine the load on roof structure. Therefore, the proper and accurate calculating methods of support resistance are established. Based on this, the dynamic structure theory in shallow seam could be predicted.

Research on Pressure Tight Sampling Technique of Deep-Sea Shallow Sediment—A New Approach to Gas Hydrate Investigation

Analyzed and calculated are pressure changes and body deformation of the sample inside of the corer in the process of sampling of deep-sea shallow sediment with a non-piston corer for gas hydrate investigation, Two conclusions are drawn： （1） the stress increments associated with the corer through the sampling process do not affect the stabilization of the gas hydrate; （2） the body deformation of the sample is serious and the ＂incremental filling ratio＂ （IFR） is less than unit, For taking samples with in-situ pressure and structure, combining with the design theories of the pressure tight corer, we have designed a kind of piston corer, named the gas hydrate pressure tight piston corer, Several tests on the sea have been conducted. Test results indicate that the piston corer has a good ability of taking sediment samples on the seafloor and maintaining their original in-situ pressure, meeting the requirement of exploration of gas hydrate in deep-sea shallow sediment layers.

Mechanical Behavior and Failure Mechanism of 2.5D(Shallow Bend-joint, Deep Straight-joint) and 3D Orthogonal UHWMPE Fiber/Epoxy Composites by Vacuum-assistant-resin-infused

Ultra-high molecular weight polyethylene（UHMWPE） fiber/epoxy composites were fabricated by a vacuum assisted resin infused（VARI） processing technology. The curing condition of composites was at a cure temperature of 80 ℃ for 3h in a drying oven. The characteristics of 2.5D（shallow bend-joint and deep straight-joint） structure and 3D orthogonal structure were compared. The failure behavior, flexural strength, and microstructures of both composites were investigated. It was found that the flexural property was closely related to undulation angle θ. The flexural strength of 3D orthogonal structure composite was superior to the other two structures composites with the same weave parameters and resin.

A Comparison of Shale Gas Fracturing Based on Deep and Shallow Shale Reservoirs in the United States and China

China began to build its national shale gas demonstration area in 2012.The central exploration,drilling,and development technologies for medium and shallow marine shale reservoirs with less than 3,500m of buried depth in Changning-Weiyuan,Zhaotong,and other regions had matured.In this study,we macroscopically investigated the development history of shale gas in the United States and China and compared the physical and mechanical conditions of deep and shallow reservoirs.The comparative results revealed that themain reasons for the order-ofmagnitude difference between China’s annual shale gas output and the United States could be attributed to three aspects:reservoir buried depth,reservoir physical and mechanical properties,and engineering technology level.The current engineering technology level of China could not meet the requirements of increasing production and reducing costs for deep shale gas reservoirs;they had reached the beneficial threshold development stage and lacked the capacity for large-scale commercial production.We identified several physical and mechanical reasons for this threshold development stage.Deep shale reservoirs were affected by the bedding fracture,low brittleness index,low clay mineral content,and significant areal differences,as well as by the transformation from elasticity to plasticity,difficulty in sanding,and high mechanical and strength parameters.Simultaneously,they were accompanied by six high values of formation temperature,horizontal principal stress difference,pore pressure,fracture pressure,extension pressure,and closure pressure.The key to deep shale gas horizontal well fracturing was to improve the complexity of the hydraulic fracture network,formadequate proppant support of fracture surface,and increase the practical stimulated reservoir volume(SRV),which accompanied visual hydraulic discrete network monitoring.On this basis,we proposed several ideas to improve China’s deep shale gas development involving advanced technology systems,developing tools,and supporting technologies in shale gas exploration and development in the United States.These ideas primarily involved stimulation technologies,such as vertically integrated dessert identification and optimization,horizontal well multistage/multicluster fracturing,staged tools development for horizontal wells,fractures network morphology monitoring by microseismic and distributed optical fiber,shale hydration expansion,soak well,and fracturing fluid flow back.China initially developed the critical technology of horizontal well large-scale and high-strength volume fracturing with a core of“staged fracturing with dense cutting+shorter cluster spacing+fracture reorientation by pitching+forced-sand addition+increasing diameter perforating+proppant combination by high strength and small particle size particles”.We concluded that China should continue to conduct critical research on theories and technical methods of horizontal well fracturing,suitable for domestic deep and ultra-deep marine and marine-continental sedimentary shale,to support and promote the efficient development of shale gas in China in the future.It is essential to balance the relationship between the overall utilization degree of the gas reservoir and associated economic benefits and to localize some essential tools and supporting technologies.These findings can contribute to the flourishing developments of China’s deep shale gas.

Resistance Analysis of a Semi-SWATH Design Concept in Shallow Water

Resistance analysis is an important analytical method used to evaluate the hydrodynamic performance of High Speed Craft (HSC). Analysis of multihull resistance in shallow water is essential to the performance evaluation of any type of HSC. Ships operating in shallow water experience increases in resistance because of changes in pressure distribution and wave pattern. In this paper, the shallow water performance of an HSC design concept, the semi-Small Waterplane Area Twin Hull (semi-SWATH) form, is studied. The hull is installed with fin stabilizers to reduce dynamic motion effects, and the resistance components of the hull, hull trim condition, and maximum wave amplitude around the hull are determined via calm water resistance tests in shallow water. These criteria are important in analyzing semi-SWATH resistance in shallow water and its relation to flow around hull. The fore fin angle is fixed to zero degrees, while the aft fin angle is varied to 0o, 5o, 10o, and 15o. For each configuration, investigations are conducted with depth Froude numbers (FrH) ranging from 0.65 to 1.2, and the resistance tests are performed in shallow water at the towing tank of UTM. Analysis results indicate that the resistance, wave pattern, and trim of the semi-SWATH hull form are affected by the fin angle. The resistance is amplified whereas the trim and sinkage are reduced as the fin angle increases. Increases in fin angle contribute to seakeeping and stability but affect the hull resistance of HSCs.

Distinctive Drug-resistant Mutation Profiles and Interpretations of HIV-1 Proviral DNA Revealed by Deep Sequencing in Reverse Transcriptase

Objective To investigate distinctive features in drug-resistant mutations （DRMs） and interpretations for reverse transcriptase inhibitors （RTIs） between proviral DNA and paired viral RNA in HIV-l-infected patients. Methods Forty-three HIV-l-infected individuals receiving first-line antiretroviral therapy were recruited to participate in a multicenter AIDS Cohort Study in Anhui and Henan Provinces in China in 2004. Drug resistance genotyping was performed by bulk sequencing and deep sequencing on the plasma and whole blood of 77 samples, respectively. Drug-resistance interpretation was compared between viral RNA and paired proviral DNA. Results Compared with bulk sequencing, deep sequencing could detect more DRMs and samples with DRMs in both viral RNA and proviral DNA. The mutations M1841 and M2301 were more prevalent in proviral DNA than in viral RNA （Fisher＇s exact test, P〈0.05）. Considering ＇majority resistant variants＇, 15 samples （19.48%） showed differences in drug resistance interpretation between viral RNA and proviral DNA, and 5 of these samples with different DRMs between proviral DNA and paired viral RNA showed a higher level of drug resistance to the first-line drugs. Considering ＇minority resistant variants＇, 22 samples （28.57%） were associated with a higher level of drug resistance to the tested RTIs for proviral DNA when compared with paired viral RNA. Conclusion Compared with viral RNA, the distinctive information of DRMs and drug resistance interpretations for proviral DNA could be obtained by deep sequencing, which could provide more detailed and precise information for drug resistance monitoring and the rational design of optimal antiretroviral therapy regimens.

Study on relationship between deep and shallow structures along north boundary fault of Yanqing-Fanshan basin

Based on the results of surface geology, shallow and deep seismic survey, features of micro-earthquake activity along the north boundary fault of Yanqing-Fanshan sub-basin and their relationship with the surface active faults and the deep-seated crustal structure are analyzed using the recordings from the high-resolution digital seismic network. The focal mechanism solutions of micro-earthquakes, whose locations are precisely determined by the seismic network, have confirmed the structural characteristics to be the rotational planar normal fault and demon-strated the surface traces of the north boundary fault of Yanqing-Fanshan sub-basin. By using the digital recordings of earthquakes with the high resolutions and analyzing the mechanism solutions, our study has revealed the rela-tionship between the geological phenomena in the shallow and deep structures in Yanqing-Huailai basin and the transition features from the brittle to ductile deformation with the crustal depth.

Microstructure of deep cryogenic treatment electrode for resistance spot welding of aluminium alloy

Cr-Zr-Cu alloy electrodes for resistance spot welding of aluminium alloy are treated by deep cryogenic treatment processes. The Cr-Zr-Cu alloy electrodes are analyzed by transmission electron microscope（ TEM ） , and results show that the common dislocation in Cr-Zr-Cu alloy electrodes is changed into the dislocation loop, and twin crystal is found after deep cryogenic treatment. The parallel twin crystal band is observed by selected electron diffraction（SED） and the twin crystal plane is marked as （ 111 ）. The Cr-Zr-Cu alloy electrode is studied by X-ray diffraction（ XRD ） and results show that the intensity of diffraction peak is obviously changed after deep cryogenic treatment, and the grain rotates to preferred orientation. The Cr-Zr- Cu alloy electrode is studied by positron annihilation technique （PAT） and results indicate that the amount of vacancy defects is less than that of Cr-Zr-Cu alloy before deep cryogenic treatment. The main elements in Cr-Zr-Cu alloy are studied with X- ray photoelctron spectroscopy（ XPS ） and the intensity of spectrum peak is increased after deep cryogenic treatment.

Delay Resistant Transport Protocol for Deep Space Communication

The throughput of conventional transport protocols suffers significant degradation with the increased Round Trip Time (RTT) typically seen in deep space communication. This paper proposes a Delay Resistant Transport Protocol (DR-TCP) for point-to-point communication in deep space exploration missions. The issues related to deep space communication protocol design and the areas where modifications are necessary are investigated, and a protocol is designed that can provide good throughput to the applications using a deep space link. The proposed protocol uses a cross layer based approach to find the allocated bandwidth and avoids initial bandwidth estimation. A novel timeout algorithm estimates the timeout duration with an objective to maximize throughput and avoid spurious timeout events. The protocol is evaluated through extensive simulations in ns2 considering high RTT values typically seen in Lunar and Mars Exploration Networks under different conditions of packet error rates. DR-TCP provides a significant increase in the throughput as compared to traditional transport protocols under the same conditions. A novel adaptive redundant retransmission algorithm is also presented to take care of the high PER in deep space links. The effect of the Retransmission Frequency has been critically analyzed considering both Lunar and Deep Space scenarios under different levels of PER. The results are very encouraging even in high error conditions. The protocol exhibits a RTT independent behavior in throughput, which is the most desirable quality of a protocol for deep space communication.

Numerical Simulation of Installation Process and Uplift Resistance for An Integrated Suction Foundation in Deep Ocean

A concept design, named integrated suction foundation, is proposed for a tension leg platform（TLP） in deep ocean. The most important improvement in comparing with the traditional one is that a pressure-resistant storage module is designed. It utilizes the high hydrostatic pressure in deep ocean to drive water into the module to generate negative pressure for bucket suction. This work aims to further approve the feasibility of the concept design in the aspect of penetration installation and the uplift force in-place. Seepage is generated during suction penetration, and can have both positive and negative effects on penetration process. To study the effect of seepage on the penetration process of the integrated suction foundation, finite element analysis（FEA） is carried out in this work. In particular, an improved methodology to calculate the penetration resistance is proposed for the integrated suction foundation with respect to the reduction factor of penetration resistance. The maximum allowable negative pressure during suction penetration is calculated with the critical hydraulic gradient method through FEA. The simulation results of the penetration process show that the integrated suction foundation can be installed safely. Moreover, the uplift resistance of the integrated suction foundation is calculated and the feasibility of the integrated suction foundation working on-site is verified. In all, the analysis in this work further approves the feasibility of the integrated suction foundation for TLPs in deep ocean applications.

Research on the Characteristics of Deep and Shallow Structures in Shenyang City and Their Relationship with Seismic Activities

Deep and shallow tectonic data in Shenyang and its relationship with seismic activity shows that the NE trending faults developed on the surface control the formation and development of the fault-uplift and fault-depression. The uplift and depression of the bedrock at a depth of 7km underground are＇consistent with the surface structure. 12 planar listric normal faults have developed above a depth of 18km -20km and two deep faults have developed in the lower crust. Because of the deep incision and new activities, the surface Wanggangpu-Xinehengzi fault and Yongle-Qingshuitai fault, which correspond to the deep F3 fault and F6 fault, might be related to seismic activity in Shenyang.

P-wave tomography and relation between shallow and deep structures beneath the Songliao basin

We selected relative travel-time residuals from teleseismic waveform data using the waveform correction method and imaged the P wave velocity structure beneath Northeast China. In combination with other geophysical data, we discussed the relation between the shallow and deep structures of the area. The results show that there is a primary high-velocity zone with some high- and low-ve- locity distribution characters beneath the Songliao basin. The low-velocity anomalies may extend down to the upper mantle, and may be the result of material upwelling. The low-velocity anomaly beneath the southern part of the Songliao basin is connected to those beneath the Chang- baishan and A＇ershan volcanic areas. It may be an upwelling channel from the mantle beneath the Songliao basin and adjacent area. This finding indicates the Songliao basin was a result of asthenospheric upwelling caused by subduction of the Pacific plate under the Eurasian plate.

The Method for Inferring a Buried Fault from Resistivity Tomograms and Its Typical Electrical Features

Electrical resistivity tomography (ERT) has been used to experimentally detect shallow buried faults in urban areas in the past a few years, with some progress and experience obtained. According to the results from Olympic Park, Beijing, Shandong Province, Gansu Province and Shanxi Province, we have generalized the method and procedure for inferring the discontinuity of electrical structures (DES) indicating a buried fault in urban areas from resistivity tomograms and its typical electrical features. In general, the layered feature of the electrical structure is first analyzed to preliminarily define whether or not a DES exists in the target area. Resistivity contours in resistivity tomograms are then analyzed from the deep to the shallow. If they extend upward from the deep to the shallow and shape into an integral dislocation, sharp flexure (convergence) or gradient zone, it is inferred that the DES exists, indicating a buried fault. Finally, horizontal tracing is be carried out to define the trend of the DES. The DES can be divided into three types-type AB, ABA and AC. In the present paper, the Zhangdian-Renhe fault system in Zibo city is used as an example to illustrate how to use the method to infer the location and spatial extension of a target fault. Geologic drilling holes are placed based on our research results, and the drilling logs testify that our results are correct. However, the method of this paper is not exclusive and inflexible. It is expected to provide reference and assistance for inferring the shallow buried faults in urban areas from resistivity tomograms in the future.