Search

Myanmar occupies a complex region in the active Indo-Burma subduction system. To illuminate the upper 10 km crustal structure of central Myanmar and obtain new insight into the subduction system, we jointly use P-wave polarizations and receiver functions (RFs) to construct a high-resolution VS profile based on a Bayesian Markov chain Monte Carlo approach. This obtained profile clearly delineates six tectonic units and their boundaries, including the Indo-Burman ranges (IBR), the IBR-fore-arc basin boundary, the fore-arc basin, the volcanic arc, the back-arc basin, and the Sunda plate. The Sunda plate has relatively higher upper crustal VS ( >3.0 km/s) and thinner sedimentary cover ( ∼1 km) compared with the Central Myanmar basin in the Burma plate. The fore-arc basin, containing thick sediments ( >10 km), and the back-arc basin, with thinner sediments ( ∼1-6 km), are separated by a region with higher VS ( ∼3.0 km/s), which represents crystallized magma beneath the volcanic arc. A narrow zone of relatively high-VS ( ∼2.6-2.7 km/s) ophiolites is situated between the fore-arc basin and the IBR. We also find a narrow zone of high-VS ( ∼2.9 km/s) metamorphic rocks contained within the low-VS (≳2.3 km/s) IBR. This study suggests that the proposing joint inversion of two types of single-station measurements, that is, P-wave polarizations and RFs, can robustly and computationally efficiently image the shallow VS structure and provide a reliable uncertainty estimation. Ministry of Education (MOE) National Research Foundation (NRF) This research was supported by the National Research Foundation of Singapore and the Singapore Ministry of Education under the Research Centers of Excellence initiative, via the Earth Observatory of Singapore (EOS) Grant Numbers 04MNS001953A620 and 04MNS001913A620. J. Yao and P. Tong were also partly supported by the Ministry of Education Singapore Academic Research Funding Tier 2 Grant MOE2019-T2-2-112 and MOE2018-T2-1-059.

Many factors affect the reaction characteristics of nitrogen oxides and SO2 in a dielectric barrier discharge reactor. Changing the SO2 initial concentration, oxygen content and water vapor content to study the reaction mechanism of NO and SO2 in the dielectric barrier discharge plasma process has been conducted. It was shown that the initial concentration of SO2 varied in a larger scope has little effect on the reaction characteristics of NO and SO2 in the N2/SO2/NO system. Increasing the water vapor content in the N2/NO/SO2/HO system would reduce the concentration of SO2 significantly in the flue gas, and the influence on SO2 is more obvious than on NO. Then, the influence of oxygen on the reaction characteristics of SO2 is not obvious, increasing the O2 concentration in the N2/NO/SO2/O2 system, the changed of SO2 concentration is less than 10%. But the adding of O2 affects the reaction of NO in the dielectric barrier discharge process obviously, it can promote the conversion of NO2 and other NOx, at the same time, the generation of NO was also being accelerated under certain conditions. By analyzing the reaction mechanism, it was found that the activated radicals produced in the dielectric barrier discharge process concerned SO2 reaction mainly OH, while related the reaction of NO, the O and N play an important role. Through the experiment and analysis, it was also deduced that there are oxidation and reduction reactions existed at the same time, also the generation and removal of NO occurred simultaneously.

The recycling of oceanic lithosphere into the deep mantle at subduction zones is one of the most fundamental geodynamic processes on Earth. During the closure of an ocean, ancient oceanic slabs are thought to be consumed entirely in subduction zones due to their negative buoyancy. Yet, it is recently suggested that small pieces of oceanic slabs could be trapped along paleo-subduction zones. What remains far more enigmatic is whether significant portions of paleo-oceanic lithosphere could eventually avoid the fate of subduction and be accreted to continental lithosphere, thus contributing to continental growth through time. We present seismic evidence for a preserved paleo-oceanic lithosphere beneath the Junggar region in northwestern China. We show that unsubducted oceanic lithosphere in the West Junggar has been preserved beneath the Junggar Basin, becoming a piece of the Eurasian continent. This scenario is likely to have occurred in other continents throughout Earth’s history, providing an additional and commonly underestimated contribution to the growth of continental lithosphere.

Detailed description of the seismic imaging methods and resolution analyses.

Crustal deformation in the Sierra Nevada and Walker Lane is mainly investigated by geologic and geodetic constraints which suffer from a lack of depth information. In this study, we construct a new depth-dependent azimuthally anisotropic P-wave velocity (Vp) model of this area to investigate regional deformation regimes in the upper and middle crust. The model is built based on adjoint-state traveltime tomography of ∼650,000 local direct P arrivals collected from 1967 to 2021. The average Vp structure agrees well with previous tomographic models with refined velocity features benefiting from the ray-free adjoint-state tomography and more arrival time data. The azimuthal anisotropy of Vp reveals distinct differences between the rigid Sierra Nevada block and the Walker Lane shear zone: (a) The western Sierra Nevada shows weak anisotropy (

Characteristics of the subducting crust and the attached sedimentary cover play a key role in shaping the structure and processes in the hanging wall of a convergent plate boundary. Such influence must be significant in the oblique Indo-Burma subduction zone. Yet, the poorly resolved shallow crustal velocity structure of the overriding Burma plate, especially its lateral variation along the subduction margin, hinders a comprehensive understanding of the Indo-Burma subduction dynamics. Here, we take advantage of the new and dense broadband seismic data in Myanmar to image the regional S-wave velocity (Vs) structure in the top 10 km of crust by joint inversion of Rayleigh-wave ellipticity, receiver function and P-wave polarization. The new velocity model not only matches surface geology and seismic reflection profiles, but also reveals new and rapidly varying near-surface features, including (1) the exhumed high-velocity metamorphic belt of the Indo-Burma accretionary prism, which is more prominent in the south with a shallower depth extent and greater Vs of ∼3.5 km/s; and (2) contrasting Vs structure beneath the two Quaternary volcanoes, that is, Vs of typical crystallized igneous rocks (∼3 km/s) beneath Monywa versus Vs slower than the adjacent basin sediments (

Because an oceanic plate colliding with a continental plate will usually be subducted and recycled into the deep mantle, a fossil oceanic plate after the closure of an ancient ocean has rarely been imaged in the subcontinental lithospheric mantle. This has led to a long-standing debate about the fate of subducted ocean plates. The problem can be addressed by imaging the lithosphere in a continental accretion zone with past ocean subduction. We present a study using long-period magnetotelluric data that reveals a large shallow-mantle conductor in a Phanerozoic accretion area in northwestern Xinjiang, China. This conductor extends >300 km laterally at depths from 120 to 220 km and resembles a segment of a fossil oceanic plate. The reduced resistivity is ascribed to the volatile-bearing metasomatic minerals, based on its relatively fertile nature and low temperature. Our results demonstrate that an oceanic plate can be trapped in continental lithosphere, underscoring the significance of oceanic plate subduction to continental accretion, and shedding new light on our understanding of continental formation and evolution.

The Moho discontinuity plays an important role in crustal growth and evolution. In this study, we delineate the Moho geometry in southern California by jointly using local Moho-reflected waves PmP and teleseismic Moho-converted waves Ps. To well constrain the Moho geometry, we have developed a two-stage process to pick PmP waves and have created a reliable PmP travel time data set with a total of 10,192 picks. We have also extracted 38,648 high-quality P-wave receiver functions (RFs). The Moho depth is initially estimated via the common conversion point (CCP) stacking of RFs and then refined by inverting the PmP travel time data in a community velocity model (CVM-H, version 15.1.1). The newly built Moho geometry is generally consistent with the California Moho Model version 1.0 (CMM-1.0), that is, a shallow Moho beneath the Salton Trough (23 km), a uniformly shallow Moho beneath the Mojave Desert and the Basin and Range (34 km). However, our Moho model reveals some new features different from the CMM–1.0, such as a deep Moho (∼34 km) beneath the northern end of the central and western Transverse Ranges, consistent with the observation of deep seismicities due to a thick brittle crust there. We also find a gradual transition from the lower crust to the uppermost mantle beneath the western Peninsular Ranges, leading to the rareness of pickable PmP waves as well as weak Moho-converted signals there. Ministry of Education (MOE) National Research Foundation (NRF) Published version This research is partly funded by the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centers of Excellence Initiative (Project Code Number: 04MNS001953A620). T. Li and P. Tong are also partly supported by Singapore MOE AcRF Tier-2 Grant (04MNP002073C230).

The lower crust plays an important role in coupling the upper mantle force to the brittle upper crust at transform plate boundary regions. Yet, the tomographic resolution in the lower crust is typically much lower than the upper crust, given that most earthquakes take place at seismogenic depths. Here, we present a new P-wave velocity model of the entire crust in southern California by jointly inverting arrival times of first P and Moho reflected PmP waves. A total of 29,512 robust PmP arrivals are picked by a new semi-automatic workflow, forming the largest earthquake-sourced PmP dataset in southern California to date. Such abundant PmP arrivals remarkably improve the resolution of middle and lower crust in tomographic imaging. Our final velocity model reveals prominent low-velocity anomalies beneath the Eastern California Shear Zone (ECSZ) and south of the Coso Volcanic Field (CVF) in the lower crust. We attribute the low velocities beneath the ECSZ to deep fluid concentration which not only triggers major crustal earthquakes but may also contribute to the long-term development of the shear zone. While the low-velocity anomaly south of the CVF may imply the deep magma source of the CVF is located to its south. Ministry of Education (MOE) National Research Foundation (NRF) This study is supported by the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centers of Excellence Initiative (04MNS001913A620 and 04MNS001953A620). P. Tong is also supported by MOE AcRF Tier-2 Grant MOE2019-T2-2-112 and MOE AcRF Tier-1 Grant RG118/19(S).

The magma plumbing in the lower crust beneath the Coso volcanic field (CVF) remains controversial, largely because of the absence of high-resolution lower crustal velocity models. For the first time, we develop a high-resolution crustal P-wave velocity model for the Coso-Ridgecrest region by jointly inverting 137,992 first P and 8,636 PmP travel-time data using an eikonal equation-based seismic reflection tomography method. More than half of the PmP travel times are picked from earthquakes after the 2019 Mw 7.1 Ridgecrest earthquake. Such abundant PmP travel times significantly improve the resolution of the lower crust. Our final velocity model reveals a prominent low-velocity body sitting right beneath the CVF at 5–20 km depths, which we interpret as a rhyolite magma reservoir that supplies heat flux to the hot springs and also feeds the volcanic activities at Coso. We find that the upper-middle crustal low-velocity body dips southwards into the lower crust, extending to regions beneath the Indian Wells Valley and the Garlock Fault at depth greater than 20 km. We ascribe the lower crustal low-velocity body (more than 4% Vp reduction) to a basaltic magma reservoir that connects the melts in the uppermost mantle with the eruptible rhyolitic reservoir at shallower depths. The basaltic magma reservoir constitutes an important part of a continuous N-S elongated crustal magma plumbing system beneath the CVF, formed as a combined result of local extension, faulting, and stress distribution. Ministry of Education (MOE) National Research Foundation (NRF) Published version This study is supported by the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centers of Excellence Initiative (04MNS001913A620 and 04MNS001953A620). This study is also supported by the National Natural Science Foundation of China (42174084) and Fundamental Research Funds for the central Universities (JZ2021HGPB0058). The authors gratefully appreciate the financial support from China Scholarship Council (201906690020).

We present a high-resolution P-wave azimuthally anisotropic velocity model for the upper and middle crust beneath southern California by a novel adjoint-state traveltime tomography technique. Our model reveals significant anisotropy variations between tectonic blocks that clearly reflect both past and current plate boundary deformation. In the shallow crust, seismic anisotropy is mostly controlled by the preferred alignment of microcracks related to the present N-S compressive stress; while at deeper depths (> ∼6 km), seismic anisotropy mainly records paleofabrics formed during the long-lived Farallon subduction and later extension that have not been fully reset by the present transform motion. Interestingly, our model demonstrates distinct fast axes beneath the western Transverse Ranges from its neighboring blocks, probably reflecting the large-scale vertical axis clockwise rotation of the block. In addition, we identify layered structures with distinct anisotropy features beneath the Salton Trough, which could be a result of the current transtension. Ministry of Education (MOE) National Research Foundation (NRF) Submitted/Accepted version This study was founded by the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centers of Excellence Initiative (04MNS001913A620 and 04MNS001953A620). PT was also supported by MOE AcRF Tier-2 (04MNP002073C230) and Tier-1 Grant (04MNP000559C230).

The Moho discontinuity plays an important role in crustal growth and evolution. In this study, we delineate the Moho topography in southern California using the local Moho-reflected PmP waves and t...

Limited by the computing capacity of current computer and difficulty in inversion of large quantity of reservoir parameters for large scale reservoir history matching, the current automatic history matching methods are still hard to be applied in real fields. A parameterization method based on matrix decomposition is proposed to reduce the computational cost and improve the efficiency of history matching without decreasing the precision by mapping the original optimization problem from high dimensional space to low dimensional space. Base on the updated reservoir model after history matching, a reservoir production optimization control model is established. Considering the complexity of gradient calculation for history matching and production optimization objective function, a new general upscaling stochastic approximation (GUSA) algorithm is given based on the approximation perturbation gradient algorithm. The GUSA algorithm aims to get maximum increment of an objective function in unit step by obtaining an optimal lower triangular matrix in each iterative step. Toy problem results show that the calculation efficiency is improved much compared with the simultaneous perturbation stochastic approximation (SPSA) algorithm. For application of a real reservoir, a good history matching result is obtained for historic production data that verifies the validity of parameterization method and GUSA algorithm. An optimal control for production optimization performs an increase of oil production and a decrease of water cut. Besides, the optimal production scheme is accordant with the practical characteristics of dynamic production, which also proves the availability of GUSA algorithm.

The absence of fine lithospheric-scale velocity models beneath Myanmar makes it difficult to understand the neotectonics and geodynamics along the Indo-Burma subduction zone. In this study, we present a high-resolution crustal and uppermost mantle 3-D shear-wave velocity (Vs) model of Myanmar to fill this knowledge gap, using ambient noise data from newly deployed seismic arrays. In the upper crust, our model reveals two thick (>10 km) N-S-elongated basins between the Indo-Burman Ranges and the Central Myanmar Basin. At middle to lower crustal depths, low velocities dominate the Indo-Burman Ranges, especially in its northern part where Vs is observed to be as low as ∼3.2 km/s in the lower crust. This feature is interpreted as sediments that were deposited west of the ranges and have since been subducted northeastward and accreted onto the overriding plate. Furthermore, our model reveals an N-S trending high-velocity anomaly beneath the Sagaing Fault, which could be explained by solidified basaltic magma that intruded upwards from the mantle where a low-velocity anomaly is imaged. In the upper mantle, the subducting Indian Plate is clearly imaged beneath Myanmar as an east-dipping high-velocity zone, overlain by a prominent wedge-shaped low-velocity body (Vs < 4.3 km/s). We interpret this low-velocity anomaly to represent partial serpentinization (19–38%) in the forearc mantle. The size and amplitude of this anomaly decrease towards the north, suggesting a northward reduction in serpentinization level within the forearc mantle, possibly related to a northward reduction of water in the subduction zone. This could be associated with lower water content in the subducting plate, as the thick sediments deposited in the north may have driven water out of the lowermost section, while the upper sedimentary section, which could still have been carrying water, would have been scraped off of the downgoing plate and accreted onto the overriding plate, forming part of the Indo-Burman Range. Ministry of Education (MOE) National Research Foundation (NRF) This research was supported by the National Research Foundation of Singapore and the Singapore Ministry of Education under the Research Centres of Excellence initiative, via the Earth Observatory of Singapore (EOS) grants 04MNS001913A620, 04MNS001848A620, and 04MNS001953A620. J. Yao and P. Tong were also partly supported by the Ministry of Education Singapore Academic Research Funding (MOE AcRF) Tier 1 Grant (04MNP000559C230) and Tier 2 Grant (04MNP000797C230). Y. Wang is funded by the Ministry of Science and Technology, Taiwan (MOST; 108-2119-M-001-019 and 108-2116-M-002-001MY3).

A unified data environment is established in China Integrated Meteorological Information Sharing System (CIMISS) or the national meteorological service. The paper discusses the establishment of provincial meteorological service system application flow and scheme based on unified data environment. It creates a seamless integration between local system and China Integrated Meteorological Information Sharing System without changing business processes and system architecture of existing meteorological service system. In the design scheme, the meteorological data is obtained by the multiple services based on unified data environment and data interface. According to different data structures, analytical methods of discrete data, gridded data and raster data are discussed. Finally, efficient and rapid visualization of meteorological data is realized. The result shows that the application flow and scheme that China Integrated Meteorological Information Sharing System used in provincial meteorological service system are effective and feasible. It is hoped that the studies of this paper can provide a reference for accessing unified national meteorological data environment for meteorological service system.

We present new crustal models of azimuthally anisotropic P-wave velocity, isotropic P-wave velocity (Vp), isotropic S-wave velocity (Vs) and Vp/Vs ratio for the Salton Trough. High Vp/Vs ratio is revealed at depths of 2–8 km along the San Andreas Fault, implying the possible presence of fluids. High Vp and high Vp/Vs ratio (>1.8) structures of the mid-lower crust beneath the Salton Trough possibly reflect the underplated gabbroic rocks as a result of the extension-induced partial melting of the upwelling asthenospheric materials. The fast velocity directions (FVDs) generally correlate with the direction of the maximum horizontal compressive stress except that fault-parallel FVDs are found at main fault traces. However, the FVDs in the Salton Trough show complex features. The northern Slaton Trough basin (the northern Salton Sea basin and Coachella Valley basin) is dominated by NW-SE FVDs, which are possibly due to the active compression happening there. E-W oriented FVDs predominate the upper crust of the southern Salton Trough basin (the southern Salton Sea basin and Imperial Valley basin), possibly due to faulting and/or block rotation. As the depth increases (12–18 km), the FVDs to the south of the Salton Sea have an overall rotation and gradually become NW-SE. The depth-dependent variation of anisotropy orientation may be attributed to a large band of underlying heat source that probably causes a change of stress field by imposing thermal stress on overlying rocks. In all, our velocity models suggest that faults in the Salton Trough may bear a high risk of mechanical failures due to the complexities of stress distribution and geological structures as well as the presence of a large volume of fluids and heat. Ministry of Education (MOE) National Research Foundation (NRF) This work is funded by MOE AcRF Tier-2 Grant MOE2019-T2-2-112 and MOE AcRF Tier-1 Grant RG118/19(S). This research is also partly supported by the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centers of Excellence Initiative (Project Code Number: 04MNS001953A620).

Previous studies showed that metal preconcentration in fluids and/or magma is critical to the formation of gold deposit in arcs and is closely related to the segregation of sulfide phases. However, the depth range and the magnitude of and associated mechanism by which the deep crust controls the metal preconcentration of arc mineralization remain enigmatic. Here we present geophysical observations of the medium-scale Baogutu porphyry copper–gold deposit and the large-scale Hatu epithermal gold deposit from the late Paleozoic arc in the western Junggar, NW China. During the closure of Paleo-Asian Ocean, Baogutu deposit formed at ∼313 Ma relating to the adakitic intrusions driven by the ridge-related subduction, and Hatu deposit formed at ∼300 Ma just before the subduction termination. The transcrustal structures of resistivity and shear-wave velocity would show the signatures of metal preconcentration by reasoning the cause of low-resistivity anomaly to the persisting sulfide phases and the change of shear-wave velocity to the garnet proportion, respectively. Our results showed that the sulfide phases persisted in the entire deep crust and thus the metal preconcentration could occur in the base cumulates and mush reservoir beneath Hatu deposit, but the signatures were not fully reflected beneath the Baogutu deposit. These observations suggest that the reduced permeability of brittle-ductile transition and the water flux associated with magma likely affect the rising rate of melt, resulting in different efficiency of the metal preconcentration. Thus, the endowments of mineralization in arcs are controlled by crustal structures and contemporaneous arc magmatism during subduction.

In this study, an activated porous graphite oxide (PG) with a superior surface area of ~ 3010 m2 g− 1 was applied as electrode component for discrimination of dopamine (DA) and uric acid (UA) via cyclic voltammetry (CV), in the presence of high content of ascorbic acid (AA). Contributable to microwave exfoliation and KOH assisted activation, the as-prepared PG remarkably improves the signal at glassy carbon electrode (GCE) for analyte. The electrochemical performance of PG/GCE was studied with CV and electrochemical impedance spectroscopy (EIS) measurements. The CV data implied that the PG film effectively enlarges the electro-active area of the working electrode while the EIS data revealed that the PG modification enhances the electron transfer kinetics between analyte and electrode. The peak separations between DA, UA and AA were remarkably enlarged and their redox peak currents were enhanced. This makes the proposed sensor feasible for simultaneous determination of DA and UA in the presence of AA. Under optimum conditions, the oxidation peak currents for DA and UA increased linearly over concentration ranges of 0.5–60 μM and of 0.5–100 μM, with detection limits of 0.04 μM and 0.02 μM (at a signal-to-noise ratio of 3, S/N = 3), respectively. Applications of the PG/GCE for urine and serum analyses were investigated. The results with good recoveries indicate the feasibility of the developed electrode in clinic sensing application.

The rapid growth of household electricity consumption is threatening the sustainable development of China&rsquo, s economy and environment because of its impacts on the operation efficiency of the electric power system. To recognize the driving factors of the consumption growth and offer policy implications, based on the consumption-related data of 2015 and 2016, this research used the rank sum ratio (RSR) method to divide China&rsquo, s 30 provinces into 5 groups and a logarithmic mean Divisia index (LMDI) algorithm to decompose the composition growth of each group into the quantitative contribution of each driving factor. The following conclusions were drawn from the empirical analysis. (1) The Yangtze basin is the most vigorous region of consumption growth and should be principally monitored. (2) Climate conditions have a remarkable impact on consumption growth and should be a key consideration when making differentiated household electricity policies. (3) The rebound effect has already appeared in a few of the most developed regions. Electricity price is an effective measure in dealing with this effect. (4) The improvement of the income level is the most important driving factor for consumption growth. (5) For provinces with high growth vitality, the change in the burden level of electricity expenditure prompts consumption growth. However, for provinces with low growth vitality, the situations are opposite. (6) The impacts of electricity price and population on consumption growth are negligible.

As a crucial factor affecting water flooding in tight sandstone reservoirs, dynamic capillary pressure (DCP) has significant impact on the production performance during oil-water flow. In this work, a novel numerical simulation method with DCP is developed to study oil displacement in tight sandstone reservoirs. Based on this new model, the impacts from DCP to water/oil displacement (or water flooding effects) are analysed. The results of this work show that the effects brought by dynamic capillary pressure cannot be neglected. The more significant dynamic effects of capillary pressure correspond to the sample with lower permeability. The effect of DCP is probably a major contributor to non-linear flow (non-Darcy flow) in tight sandstone reservoirs during water flooding process. Compared with the conventional flow theory (e.g., static capillary pressure theory), our derived model with DCP can help to reduce the uncertainty in water/oil flow in tight sandstone reservoirs.

This paper introduces an online precision spindle rotation error measurement system based on three point method. In this measurement system, the connection of software and hardware, data acquisition and processing, results displaying and saving and other functions have been realized. The feasibility and reliability of the measurement system have been proved by the measurement of a machining center spindle.

Chronic wounds are difficult to heal spontaneously largely due to the corrupted extracellular matrix (ECM) where cell ingrowth is obstructed. Thus, the objective of this study was to develop a three-dimensional (3D) biodegradable scaffold mimicking native ECM to replace the missing or dysfunctional ECM, which may be an essential strategy for wound healing. The 3D fibrous scaffolds of poly(lactic acid-co-glycolic acid) (PLGA) were successfully fabricated by liquid-collecting electrospinning, with 5~20 µm interconnected pores. Surface modification with the native ECM component aims at providing biological recognition for cell growth. Human dermal fibroblasts (HDFs) successfully infiltrated into scaffolds at a depth of ~1400 µm after seven days of culturing, and showed significant progressive proliferation on scaffolds immobilized with collagen type I. In vivo models showed that chronic wounds treated with scaffolds had a faster healing rate. These results indicate that the 3D fibrous scaffolds may be a potential wound dressing for chronic wound repair. MOE (Min. of Education, S’pore) Published version

Atomic force microscopic observations on an isothermally crystallized poly(ethylene naphthalate) (PEN)/clay nanocomposite suggest that the presence of nanoclay alters the lamellar organization in PEN mainly in three ways: 1) physically blocking the crystal growth front and creating wide amorphous regions within the spherulites, which may then be filled by secondary lamellae branching out from the primary lamellae of the same spherulite, or primary lamellae developed from other nearby nucleating centers; 2) inducing random twisting of lamellae; and 3) causing irregular crystallite growth fronts, with the protrusion of some leading lamellae. In particular, the physical hindrance imposed by clay tends to be more prevalent for lamellae that grow roughly perpendicular to the clay long axes. This may give rise to an anisotropic crystalline morphology if the clay layers exhibit a preferred orientation induced by flow.

Water coning in bottom water drive reservoirs, which will result in earlier water breakthrough, rapid increase in water cut and low recovery level, has drawn tremendous attention in petroleum engineering field. As one simple and effective method to inhibit bottom water coning, shut-in coning control is usually preferred in oilfield to control the water cone and furthermore to enhance economic performance. However, most of the water coning researchers just have been done on investigation of the coning behavior as it grows up, the reported studies for water cone subsidence are very scarce. The goal of this work is to present an analytical model for water cone subsidence to analyze the subsidence of water cone when the well shut in. Based on Dupuit critical oil production rate formula, an analytical model is developed to estimate the initial water cone shape at the point of critical drawdown. Then, with the initial water cone shape equation, we propose an analysis model for water cone subsidence in bottom water reservoir reservoirs. Model analysis and several sensitivity studies are conducted. This work presents accurate and fast analytical model to perform the water cone subsidence in bottom water drive reservoirs. To consider the recent interests in development of bottom drive reservoirs, our approach provides a promising technique for better understanding the subsidence of water cone.

High-velocity fluid flow, which will result in the region of the wellbore or fracture, is generally in the turbulent flow regime and has drawn tremendous attention in petroleum engineering field. Turbulent factor is the key parameter, which is widely used to describe high-velocity flow in porous media. In this work, a theoretical model for turbulent factor in fractal porous media in the high-velocity fluid flow regime is developed. Moreover, a novel analytical expression for the permeability in porous media based on Wu's resistance model is also derived. Then, the analytical Kozeny-Carman constant with no empirical constant is obtained. The predictions of permeability-porosity relation by the current mathematical models have been validated by comparing with available experimental data. Furthermore, the effects of structural parameters of porous media on the curve of velocity and pressure drop are discussed in detail.

Thermally stable organically modified clays based on 1,3-didecyl-2-methylimidazolium (IM2C10) and 1-hexadecyl-2,3-dimethyl-imidazolium (IMC16) were used to prepare poly(ethylene naphthalate) (PEN)/montmorillonite (MMT) nanocomposites via a melt intercalation process. Examination by X-ray diffraction and transmission electron microscopy indicates that an intercalated nanocomposite was formed with IMC16-MMT, while unmodified MMT (Na-MMT) and IM2C10-MMT are generally incompatible with PEN. Thermogravimetric analysis reveals that the peak derivative weight loss temperature of the intercalated PEN/IMC16-MMT was more than 10 °C higher compared to neat PEN, PEN/Na-MMT, or PEN/IM2C10-MMT. Dynamic mechanical analysis also showed that a more significant improvement of the storage modulus was achieved in the better dispersed PEN/IMC16-MMT. The effect of annealing on the dynamic storage modulus of the hybrids is also investigated.

In this paper, we reported the growth of high -efficiency, high optical quality CTH:YAG laser ciystal using Czochralski method of medium frequency induction heating from iridium crucible. The slop efficiency of CTH:YAG is up to 5%.

In this paper the growth and laser properties of Nd, Ce and Cr ions-co-doped yttrium aluminum garnet (Nd:Ce:Cr:YAG) crystals were reported. Nd:Ce:Cr:YAG single crystals were grown in DJL-40D model crystal growth furnace with medium frequency induction heating by Czochralski technique from iridium crucible. The influence of the doping concentration of Nd, Ce and Cr ions on the optical quality and the pulse laser performance of the crystal and the technology conditions for growing high quality crystal were also investigated. The dimension of Nd:Ce:Cr:YAG crystal boules grown is up to (Phi) 40 multiplied by 150 mm. The interference fringe of the laser rods with the dimension (Phi) 5 multiplied by 80 mm is less than 0.5/25 mm and the extinction ratio is more than 26 dB. The pulse laser properties of Nd:Ce:Cr:YAG and ND:YAG laser rods were tested comparatively. The typical pulse laser characteristics of Nd:Ce:Cr:YAG crystal are relatively lower, threshold, higher laser efficiency, and relatively higher output power, better thermal stability and smaller nature divergence angle at Q- switching operation. At the same time, the UV radiation of pump flashlamp will not lead to the reduction of laser output.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.