In this paper, the effect of cathodic polarization on corrosion behavior of AA7003 under three kinds of aging treatments (including peak aging (PA), double peak aging (DPA) and regression re-aging (RRA)) was studied in 3.5 wt% sodium chloride solution through slow strain rate testing(SSRT) and electrochemical testing. X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods were also applied to investigating corrosion behavior and fracture morphology. The results showed that under open circuit, stress corrosion cracking (SCC) of AA7003 might by classified as anodic dissolution. In this case, the extent of SCC susceptibility (I_SCC) of AA7003 alloy with different aging treatments was as follows: I_SCC(PA)>I_SCC(DPA)>I_SCC(RRA). On the other hand, stress corrosion cracking (SCC) of AA7003 under cathodic polarization might be classified as hydrogen embrittlement (HE) which had been proved in this paper by presence of AlH3 diffraction peak in XRD patterns. In this case, for AA7003 with any of the three aging treatments, hydrogen embrittlement susceptibility (I_HE) increases with negatively shifting of cathodic polarization.

The purpose was to clarify the relationship between the main process parameters of micro-plasma cladding and the comprehensive quality (geometry, microstructure and wear rate of cladding track). Self-fluxing ferrous alloy powders were fabricated on Q235 substrate. Based on the uniform design, the distribution of the experimental samples was designed reasonably in the sample space, which greatly improved efficiency and reduced costs. After a series of microstructural characterization, there was no difference in the phase composition of all samples, but the average grain size had a significant difference, which resulted in the change of wear rate. And the relationship among micro-hardness, average grain size and wear rate of the track had also been investigated. Subsequently, an optimization model was established and the optimal process parameters were obtained with excellent wear rate under the geometric constraints. The correctness of optimization model was verified by experiments.

NASICON-type structured NaTi₂(PO₄)₃ has been regarded as a promising anode material for non-aqueous and aqueous Na-ion batteries, whereas its sodium storage performance was greatly restricted by its inherent inferior electronic conductivity. In the present work, a two-step carbon modification method using prefabricated carbon spheres as support and phenolic resin as carbon source was proposed to prepare advanced NaTi₂(PO₄)₃/C. The as-prepared composite with carbon spheres displayed a much higher reversible capacity (126.7 mA·h/g vs 106.7 mA·h/g at 0.5C) than the control sample without carbon spheres. Superior rate capability with discharge capacities of 115.1, 95.5, 80.8 mAh/g at 1C, 10C, 20C, respectively and long-term cycling stability with capacity retention of 92.4% after 1000 cycles at 5C were also observed. Owing to the designing of two-step carbon modification, although the as-prepared sample shows much smaller surface area, it possesses much better conductive network and more uniform particle distribution, resulting in higher electronic conductivity and faster ionic conductivity, thereby superior sodium storage ability at high rate.

The microstructure and electrical properties of ZnO-ZnO-Bi₂O₃-Yb₂O₃ based varistor ceramics were investigated with various temperature effects from 900 °C to 1050 °C. From the results, it was observed that the increase of sintering temperature offers a reduced capacitive effect from 0.460 nF to 0.321 nF. Furthermore, the grain sizes of varistors were varied from 6.8 μm to 9.8 μm. The consequence of such smaller grain sizes provided a better voltage gradient of about 895 V/mm for the disc sintered at 900 °C and fallen drastically to 410 V/mm for the sample sintered at 1050 °C. In addition, there was an increase of non-linearity index to a maximum value of 36.0 and reduced leakage current of 0.026 mA/cm². However, the density of the varistor decreased with an increase of temperature from 5.41 g/cm³ to 5.24 g/cm³. With this base, the influence of varistor capacitance and high voltage gradient were scrutinized and it led an improved transition speed of the varistor assembly from non-conduction to conduction mode during intruding nanosecond transients.

Fuel cell stacks as the automotive power source can be severely poisoned by a trace amount of NO_x in atmosphere, which makes it necessary to provide clean air for fuel cell vehicles. In this work, activating commercial activated carbons with K₂CO₃ for the large enhancement of NO capture was studied. K₂CO₃ modified activated carbons (K₂CO₃ ACs) were prepared by impregnating activate carbons in K₂CO₃ solution under ultrasound treatment, followed by temperature programmed baking at 800 °C. The dynamic NO flow tests on K₂CO₃ ACs at room temperature indicated that NO adsorption capacity reached the maximum (96 mg/g) when K₂CO₃ loading was 19.5 wt%, which corresponded to a specific surface area of 1196.1 m²/g and total pore volume of 0.70 cm³/g. The ten-fold enhancement of NO adsorption on K₂CO₃ ACs compared to the unimpregnated activated carbon was mainly attributed to the formation of potassium nitrite, which was confirmed by FTIR and temperature programmed desorption measurements. Regeneration tests of NO adsorption on the optimum sample revealed that 76% of the NO adsorption capacity could be remained after the fourth cycle.

A safe, economical treatment of hazardous chromium-bearing vanadate residue (CVR) will significantly benefit the clean production of chromate-bearing salts. This study investigated recovery of sodium vanadate and sodium chromate from CVR in sodium bicarbonate solution. Results indicate that the stability of calcium vanadate and calcium chromate depends on pH and [HCO₃^–]. CaV₂O₆·4H₂O transforms into CaV₂O₆·4H₂O, CaV₂O₆·2H₂O, CaV₂O₆, Ca₂V₂O₇·2H₂O, and Ca₅(VO₄)₃(OH) when pH increases from 7.51 to 12.32. Increasing pH and reducing CVR dosage improve the vanadate extraction rate, and high V₂O₅ and Na₂Cr₂O₇·2H₂O extraction rates are achieved in dilute NaHCO₃ solution. Moreover, addition of NaOH positively contributes to the recovery of vanadate and chromate from CVR. Over 95% V₂O₅ and Na₂Cr₂O₇·2H₂O in CVR can be extracted from 60 g/L NaHCO₃ and 30 g/L NaOH solutions at 90 °C for 2 h. In order to reduce the hazardous residue containing chromate after recovery of CVR, calcium circulation is presented. Results show that more than 60% lime can be saved with fresh residue addition to remove vanadate from sodium chromate solution due to the active CaCO₃. Moreover, no lime is required in removal of vanadate when the roasting residue is added. Therefore, a novel process is developed for utilization of CVR.

The strength of cement-based materials, such as mortar, concrete and cement paste backfill (CPB), depends on its microstructures (e.g. pore structure and arrangement of particles and skeleton). Numerous studies on the relationship between strength and pore structure (e.g., pore size and its distribution) were performed, but the micro-morphology characteristics have been rarely concerned. Texture describing the surface properties of the sample is a global feature, which is an effective way to quantify the micro-morphological properties. In statistical analysis, GLCM features and Tamura texture are the most representative methods for characterizing the texture features. The mechanical strength and section image of the backfill sample prepared from three different solid concentrations of paste were obtained by uniaxial compressive strength test and scanning electron microscope, respectively. The texture features of different SEM images were calculated based on image analysis technology, and then the correlation between these parameters and the strength was analyzed. It was proved that the method is effective in the quantitative analysis on the micro-morphology characteristics of CPB. There is a significant correlation between the texture features and the unconfined compressive strength, and the prediction of strength is feasible using texture parameters of the CPB microstructure.

The simulation of blast furnace slag was prepared by pure chemical reagents. Test methods like DSC, XRD and SEM were used to study the effect of Al₂O₃ and MgO content on crystallization of blast furnace slag during fiber formation. The results show that as Al₂O₃ and MgO contents in the sample changed, blast furnace slag was crystallized at the average temperature below 1232 K. When the ratio of Mg/Al in the samples is 0.6 calculated by Kissinger equation, crystallization activation energy is at the maximum value and the system is in the most stable condition. The sample crystallization phases are mainly calcium akermanite (2CaO·MgO·2SiO₂) and gehlenite (2CaO·Al₂O₃·SiO₂). Secondary crystallization phases are anorthite (CaAl₂Si₂O₈), wollastonite minerals (WOLLA) and pyroxene minerals (cPyrA). Meanwhile, the principal crystallization phases of the samples are different types and have different contents, and the microstructures of the sample sections are different due to the difference between MgO/Al₂O₃ ratio.

Many researchers found that the Fe²⁺ together with less amount of Cu²⁺ can accelerate the leaching of chalcopyrite. In this work, the leaching of chalcopyrite with Cu²⁺ was investigated. The leaching residuals were examined by Raman spectroscopy. Based on the leaching experiments, the chemical equilibrium in solution was calculated using Visual MINTEQ. The results showed that the Fe in chalcopyrite lattice was replaced by Cu²⁺; therefore, the chalcopyrite transformed into covellite. Furthermore, the formation of chalcocite occurred when Fe²⁺ and Fe³⁺ were added to the solution containing Cu²⁺. The copper extraction increased with a decrease of the initial redox potential (or the ratio of Fe³⁺/Fe²⁺).

Phase change material (PCM) can reduce the indoor temperature fluctuation and humidity control material can adjust relative humidity used in buildings. In this study, a kind of composite phase change material particles (CPCMPs) were prepared by vacuum impregnation method with expanded perlite (EP) as supporting material and paraffin as phase change material. Thus, a PCM plate was fabricated by mould pressing method with CPCMPs and then composite phase change humidity control wallboard (CPCHCW) was prepared by spraying the diatom mud on the surface of PCM plate. The composition, thermophysical properties and microstructure were characterized using X-ray diffraction instrument (XRD), differential scanning calorimeter (DSC) and scanning electron microscope (SEM). Additionally, the hygrothermal performance of CPCHCW was characterized by temperature and humidity collaborative test. The results can be summarized as follows: (1) CPCMPs have suitable phase change parameters with melting/freezing point of 18.23 °C/29.42 °C and higher latent heat of 54.66 J/g/55.63 J/g; (2) the diatom mud can control the humidity of confined space with a certain volume; (3) the combination of diatom mud and PCM plate in CPCHCW can effectively adjust the indoor temperature and humidity. The above conclusions indicate the potential of CPCHCW in the application of building energy efficiency.

In order to reduce pressure pulsation of vortex pumps, the mantis shrimp was chosen as biological prototype and a bionic engineering model was developed from its abdominal segment grooves. Bionic mantis shrimp groove volute vortex pump models with different numbers of grooves were developed, and numerical simulation methods were used to calculate the models to study the effects of the volute grooves on the pressure pulsation of a vortex pump. The results show that a bionic groove volute could effectively improve the pressure pulsation of a vortex pump outlet, and reduce the pressure pulsation around the pump’s tongue and other internal points. The pressure pulsation under different conditions is impacted by shaft frequency and blade frequency. The bionic groove structure has little effect on the external characteristics of the pump, but could improve the static pressure, velocity distribution, and vortex structure of the flow field. Additionally, pressure pulsation of the whole vortex pump is reduced.

The information centric network (ICN) has been widely discussed in current researches. The ICN interoperation with a traditional IP network and caching methods are one of the research topics of interest. For economic reasons, the capability of applying the ICN to internet service providers (ISPs) with various traditional IP protocols already implemented, especially IGP, MPLS, VRF, and TE, does not require any change on the IP network infrastructure. The biggest concern of ISPs is related to their customers’ contents delivery speed. In this paper, we consider ICN caching locations in ISP by using the concept of locator/ID separation protocol (LISP) for interoperation between a traditional IP address and name-based ICN. To be more specific, we propose a new procedure to determine caching locations in the ICN by using the cuckoo search algorithm (CSA) for finding the best caching locations of information chunks. Moreover, we create the smart control plane (SCP) scheme which is an intelligent controlling, managing, and mapping system. Its function is similar to the software defined network concept. We show how the proposed SCP system works in both synthetic small network and real-world big network. Finally, we show and evaluate the performance of our algorithm comparison with the simple search method using the shortest path first algorithm.

Building a cloud geodatabase for a sponge city is crucial to integrate the geospatial information dispersed in various departments for multi-user high concurrent access and retrieval, high scalability and availability, efficient storage and management. In this study, Hadoop distributed computing framework, including Hadoop distributed file system and MapReduce (mapper and reducer), is firstly designed with a parallel computing framework to process massive spatial data. Then, access control with a series of standard application programming interfaces for different functions is designed, including spatial data storage layer, cloud geodatabase access layer, spatial data access layer and spatial data analysis layer. Subsequently, a retrieval model is designed, including direct addressing via file name, three-level concurrent retrieval and block data retrieval strategies. Main functions are realised, including real-time concurrent access, high-performance computing, communication, massive data storage, efficient retrieval and scheduling decisions on the multi-scale, multi-source and massive spatial data. Finally, the performance of Hadoop cloud geodatabases is validated and compared with that of the Oracle database. The cloud geodatabase for the sponge city can avoid redundant configuration of personnel, hardware and software, support the data transfer, model debugging and application development, and provide accurate, real-time, virtual, intelligent, reliable, elastically scalable, dynamic and on-demand cloud services of the basic and thematic geographic information for the construction and management of the sponge city.

Due to the increasing number of cloud applications, the amount of data in the cloud shows signs of growing faster than ever before. The nature of cloud computing requires cloud data processing systems that can handle huge volumes of data and have high performance. However, most cloud storage systems currently adopt a hash-like approach to retrieving data that only supports simple keyword-based enquiries, but lacks various forms of information search. Therefore, a scalable and efficient indexing scheme is clearly required. In this paper, we present a skip list-based cloud index, called SLC-index, which is a novel, scalable skip list-based indexing for cloud data processing. The SLC-index offers a two-layered architecture for extending indexing scope and facilitating better throughput. Dynamic load-balancing for the SLC-index is achieved by online migration of index nodes between servers. Furthermore, it is a flexible system due to its dynamic addition and removal of servers. The SLC-index is efficient for both point and range queries. Experimental results show the efficiency of the SLC-index and its usefulness as an alternative approach for cloud-suitable data structures.

In this paper, a blind multiband spectrum sensing (BMSS) method requiring no knowledge of noise power, primary signal and wireless channel is proposed based on the K-means clustering (KMC). In this approach, the KMC algorithm is used to identify the occupied subband set (OSS) and the idle subband set (ISS), and then the location and number information of the occupied channels are obtained according to the elements in the OSS. Compared with the classical BMSS methods based on the information theoretic criteria (ITC), the new method shows more excellent performance especially in the low signal-to-noise ratio (SNR) and the small sampling number scenarios, and more robust detection performance in noise uncertainty or unequal noise variance applications. Meanwhile, the new method performs more stablely than the ITC-based methods when the occupied subband number increases or the primary signals suffer multi-path fading. Simulation result verifies the effectiveness of the proposed method.

The current popular methods for decision making and project optimisation in mine ventilation contain a number of deficiencies as they are solely based on either subjective knowledge or objective information. This paper presents a new approach to rank the alternatives by G1-coefficient of variation method. The focus of this approach is the use of the combination weighing, which is able to compensate for the deficiencies in the method of evaluation index single weighing. In the case study, an appropriate evaluation index system was established to determine the evaluation value of each ventilation mode. Then the proposed approach was used to select the best development face ventilation mode. The result shows that the proposed approach is able to rank the alternative development face ventilation mode reasonably, the combination weighing method had the advantages of both subjective and objective weighing methods in that it took into consideration of both the experience and wisdom of experts, and the new changes in objective conditions. This approach provides a more reasonable and reliable procedure to analyse and evaluate different ventilation modes.

Diagenetic fluid types of the Cretaceous Bashijiqike formation are restored based on the analysis of petrographic, electron microprobe composition, inclusions homogenization temperature, salinity and vapor composition and laser carbon and oxygen isotope of diagenetic mineral, and regional geological background. Diagenetic fluid evolution sequence is analyzed on this basis. The crystalline dolomite cement has a low concerntration of Sr, high concerntration of Mn and higher carbon isotope, showing that the crystalline dolomite is affected by meteoric fresh water, associated with the tectonic uplift of late Cretaceous. Similar δ¹³CPDB, negative transfer of δ¹⁸OPDB and the differentiation of the concerntration of Fe and Mn indicate that the diagenetic fluid of the vein dolomite cement is homologous with the diagenetic fluid of the crystalline dolomite cement, temperature and depth are the dominant factors of differential precipitation between these two carbonate cements. Anhydrite cements have high concerntration of Na, extremely low concerntration of Fe and Mn contents. Based on these data, anhydrite cements can be thought to be related to the alkaline fluid overlying gypsum-salt layer produced by dehydration. The barite vein has abnormally high concerntration of Sr, ultra-high homogenization temperature and high-density gas hydrocarbon inclusions, which is speculated to be the forward fluid by intrusion of late natural gas. Coexistence of methane inclusions with CO₂ gas proves existence of acid water during the accumulation of natural gas in the late stages. Therefore, the alkaline environment and associated diagenesis between the meteoric fresh water in epidiagentic stage and carbonic acid in the late diagenesis have dominated the process of diagenesis and reservoir, the secondary porosity and fracture zone formed by gas accumulation is a favorable play for the exploration of ultra-deep reservoirs.

The study area is part of the Urumieh–Dokhtar volcanic arc that a large part of its surface is covered by extrusive Igneous rocks (tuff, intermediate lavas and ignimbrites sheets), plutonic igneous (diorite and granodiorite) and semi-deep stones (dyke and sill). Studied samples are situated in calc-alkaline domain of magmatic series diagrams. Harker diagrams show the fractional crystallization of Clinopyroxene, amphibole, plagioclase, alkali feldspars and opaque minerals (ilmenite Titano-magnetite, ilmenite and rutile). In spider diagrams, light rare earth elements (LREE) are enriched compared to heavy rare earth elements (HREE), and HFS elements (Ti, Nb) show negative anomaly and LFS elements (Cs, K, Pb) show positive anomaly, showing that it is a distinct characteristic of subduction zones. Skarns of the area mainly are of exoskarns and are rich in plagioclase, microcline, amphibole, biotite and epidote. Skarn is enriched of iron, copper, molybdenum, vanadium, lead, zinc and silver. Deposits of barite in the area show characteristics of volcanic-sedimentary barites and are associated to ore-bearing hydrothermal solutions. Using satellite images and processing information, four areas with high mineral potential are identified in the area.

Anchoring mechanism and failure characteristics of composite soft rock with weak interface usually exhibit remarkable difference from those in single rock mass. In order to fully understand the reinforcement mechanism of composite soft roof in western mining area of China, a mechanical model of composite soft rock with weak interface and rock bolt which considering the transverse shear sliding between different rock layers was established firstly. The anchoring effect was quantified by a factor defined as anchoring effect coefficient and its evolution equation was further deduced based on the deformation relationship and homogenized distribution assumption of stress acting on composite structure. Meanwhile, the numerical simulation model of composite soft rock with shear joint was prompted by finite element method. Then detailed analysis were carried out for the deformation features, stress distribution and failure behavior of rock mass and rock bolt near the joint under transverse load. The theoretical result indicates that the anchoring effect of rock-bolt through weak joint changes with the working status of rock mass and closely relates with the physical and geometric parameters of rock mass and rock bolt. From the numerical results, the bending deformation of rock bolt accurately characterized by Doseresp model is mainly concentrated between two plastic hinges near the shear joint. The maximum tensile and compression stresses distribute in the plastic hinge. However, the maximum shear stress appears at the positions of joint surface. The failure zones of composite rock are produced firstly at the joint surface due to the reaction of rock bolt. The above results laid a theoretical and computational foundation for further study of anchorage failure in composite soft rock.

With the gradual depletion of mineral resources in the shallow part of the earth, resource exploitation continues to move deeper into the earth, it becomes a hot topic to simulate the whole process of rock strain softening, deformation and failure in deep environment, especially under high temperature and high pressure. On the basis of Lemaitre’s strain-equivalent principle, combined with statistics and damage theory, a statistical constitutive model of rock thermal damage under triaxial compression condition is established. At the same time, taking into account the existing damage model is difficult to reflect residual strength after rock failure, the residual strength is considered in this paper by introducing correction factor of damage variable, the model rationality is also verified by experiments. Analysis of results indicates that the damage evolution curve reflects the whole process of rock micro-cracks enclosure, initiation, expansion, penetration, and the formation of macro-cracks under coupled effect of temperature and confining pressure. Rock thermal damage shows logistic growth function with the increase of temperature. Under the same strain condition, rock total damage decreases with the rise of confining pressure. By studying the electron microscope images (SEM) of rock fracture, it is inferred that 35.40 MPa is the critical confining pressure of brittle to plastic transition for this granite. The model parameter F reflects the average strength of rock, and M reflects the morphological characteristics of rock stress–strain curves. The physical meanings of model parameters are clear and the model is suitable for complex stress states, which provides valuable references for the study of rock deformation and stability in deep engineering.

An exact solution for simply-supported laminated beams with material properties variable with temperature under a combination of uniform thermo-load and mechanical loads was investigated, based on the two-dimensional (2-D) thermo-elasticity theory. Firstly, the beam was divided into a series of layers with uniform material properties along the interfaces of the beam. The uniform thermo-load acted on each layer was transformed into a combination of the normal surface forces acted at the two ends and the transverse thermo-load. Secondly, the state space method was employed to obtain the general solutions of displacements and stresses in an arbitrary layer. Thirdly, based on the interfacial continuity conditions between adjacent layers, the relations of displacement and stress components between the top and bottom layers of the beam were recursively derived by use of the transfer-matrix method. The unknowns in the solutions can be solved by the mechanical loads acted on the top and bottom surfaces. The convergence of the present solutions was checked. The comparative study of the present solutions with the Timoshenko’s solutions and the finite element (FE) solutions was carried out. The effects of material properties variable with temperature on the thermo-elastic behavior of laminated beams were discussed in detail.

Dilation angle is a significant parameter needed for numerical simulation of tunnels. Even though dilation parameter is physically variable and dependent on confinement and experienced shear plastic strain based on the existing dilation models, numerical simulations of tunnels and underground openings with constant dilation parameter usually lead to satisfactory results in practical use. This study aims to find out why constant dilation angle is enough under practical conditions to simulate numerically tunnels and underground excavations in spite of the fact that dilation angle is variable in laboratory and experimental scale. With this aim, this work studies how mobilized dilation angle varies in a plastic zone surrounding a tunnel. For the circular tunnel under uniform in situ stress field, the stepwise finite difference approximation analytical solution considering strain softening rock mass behavior with mobilized dilation angle was used to study how mobilized dilation angle varies in plastic zone around tunnel under very different conditions. In practical conditions determined in this study, dilative behavior of all over the plastic zone around the tunnel can be approximated to constant dilation angle in the middle region of the plastic zone. Moreover, the plastic zone displacements for mobilized and constant dilation angle models are compared with each other. Further investigation under more general non-uniform in situ stress conditions and non-circular tunnels is performed by using the commercial finite difference software to numerically simulate the Mine-by experimental tunnel of AECL (Atomic Energy of Canada Limited) and the arched tunnel. Although the Mine-by and arched tunnels were numerically simulated based on the mobilized dilation angle model, the variability associated with dilation angle around the simulated Mine-by and arched tunnels is insignificant, and dilation angle is approximately constant in the plastic zone.