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The creation of ultrafine alloy nanoparticles (5 nm) that can maintain surface activity and avoid aggregation for heterogeneous catalysis has received much attention and is extremely challenging. Here, ultrafine PtRh alloy nanoparticles imprisoned by the cavities of reduced chiral covalent imine cage (PtRh@RCC3) are prepared successfully by an organic molecular cage (OMC) confinement strategy, while the soluble RCC3 can act as a homogenizer to homogenize the heterogeneous PtRh alloy in solution. Moreover, the X-ray absorption near-edge structure (XANES) results show that the RCC3 can act as an electron-acceptor to withdraw electrons from Pt, leading to the formation of higher valence Pt atoms, which is beneficial to improving the catalytic activity for the reduction of 4-nitrophenol. Attributed to the synergistic effect of Pt/Rh atoms and the unique function of the RCC3, the reaction rate constants of Pt

Structure from Motion (SfM) is key to mixed computer vision and photogrammetry applications. However, the fast-growing needs for large-scale SfM bring challenges to current SfM solutions. Unlike traditional global and incremental SfM solutions, hierarchical SfM approaches demonstrate promising potential in effectively reconstructing large-scale image sets by dividing the image set into multiple image clusters, reconstructing each cluster separately, and gradually merging partial models into a complete model. However, current hierarchical SfM approaches still suffer from the following problems: accurate image clustering without ancillary information; automatic quality evaluation of each reconstruction unit and unreliable partial reconstruction removal; effective and efficient reconstruction of each image cluster; robust and accurate cluster merging considering the merging order and the handling of images taken with the same camera but divided into different clusters. These unstable factors limit the robustness and accuracy of hierarchical SfM approaches on different unstructured image sets. To systematically improve the performance of hierarchical SfM, we propose a novel robust hierarchical structure from motion (RHSfM) method for large-scale image sets, which does not rely on any additional information, such as Global Positioning System (GPS) and Inertial Navigation System (INS). (1) We develop an automatic image clustering method based on image correlation and present a dynamic adjustment strategy, obtaining reliable image clustering results. (2) We remove the poor reconstructions by introducing multiple quality evaluation standards. (3) We put forward a fast incremental SfM algorithm that optimizes the image adding mode with an image pre-screening strategy and gets rid of the dependence by the proposed dynamic adjustment strategy. (4) We achieve accurate cluster merging by creating an optimal merging list and employing a stepwise global optimization strategy that merges structures first and then cameras. Significantly, the entire process is fully automated with only a few input parameters, and the final result is not sensitive to these parameters. We verify our method on various real image sets that cover different image conditions, different scenes, and different image scales, especially two large-scale image sets with 121,506 and 153,396 images, respectively. The experimental results reveal that our approach outperforms the state-of-the-art SfM systems Colmap, 3DF Samantha, and Metashape in terms of robustness, accuracy, and efficiency. In particular, only our method successfully reconstructed all the seven challenging datasets. For the five datasets that the other systems can also reconstruct, our method obtains the highest accuracy, which is 25 percent better than the best result of the comparable methods on average; for the remaining two datasets, the accuracy of our method is higher than 0.75 pixels. Moreover, the efficiency of our method is about 18, 4.85, and 0.25 times faster than Colmap, 3DF Samantha, and Metashape averagely on the experimental image sets, respectively. After all, our contribution provides a comprehensive and practical solution for large-scale SfM.

Freshwater flux and energy consumption are two important benchmarks for the membrane desalination process. Here, we show that nanoporous carbon composite membranes, which comprise a layer of porous carbon fibre structures grown on a porous ceramic substrate, can exhibit 100% desalination and a freshwater flux that is 3-20 times higher than existing polymeric membranes. Thermal accounting experiments demonstrated that the carbon composite membrane saved over 80% of the latent heat consumption. Theoretical calculations combined with molecular dynamics simulations revealed the unique microscopic process occurring in the membrane. When the salt solution is stopped at the openings to the nanoscale porous channels and forms a meniscus, the vapour can rapidly transport across the nanoscale gap to condense on the permeate side. This process is driven by the chemical potential gradient and aided by the unique smoothness of the carbon surface. The high thermal conductivity of the carbon composite membrane ensures that most of the latent heat is recovered.

High-resolution stratigraphic analysis of the lower second member of the Shahejie Formation of the W79 Block of Bohai Bay Basin, China, has revealed that the study area, previously interpreted as a shallow water delta system, actually mainly originated in a subaerial setting with a distributive pattern. Depositional systems of the distributive fluvial complex (DFC) have been recognized. The regional correlation of the lithofacies within the different depositional systems has led to a high-resolution-stratigraphic framework of two long-term base level cycles, six middle-term base level cycles, and more than 58 short-term base level cycles. Sequence boundary SB1 marks the top of the target interval and is characterized by thick and continuous mudstone overlying sand-rich channel sediments. Sequence boundary SB2 marks the bottom of the target interval and is characterized by stably distributed shales between sand-rich sediments. The base-level fluctuation has a strong tectonic component consistent with the regional tectonic setting; during the active subsidence stage, base-level rising semicycles were recorded in the strata, and during the relatively stable stage, base-level falling semicycles were recorded.

Fracture is one of the most important factors through the whole process of low-permeability reservoir development. Biandong oilfield is a typical low-permeability fractured sandstone reservoir, and has stepped into high water cut stage; thus, the waterflooding effect is poor. Therefore, many contradictions such as high moisture content, decreasing production speed, and low recovery efficiency are becoming increasingly prominent, which have seriously hindered the sustainable development, and need to be solved urgently. However, few such studies on reservoir characterization in low-permeability fractured sandstone reservoir have been conducted in China. In this study, through comprehensive analysis on reservoir characterization and sedimentary environment, significant results are achieved. Three types of fracture occurrence are identified; they are high-angle fracture, low-angle fracture, and horizontal fracture, respectively. Two types of reservoir pore (primary porosity and secondary porosity) are recognized based on thin-section observation and analysis. The diagenetic stage of Biandong oilfield are divided into three stages, early A, early B, and late A, respectively. Finally, a regional discrete fracture network model is established with Fisher’s algorithm based on three-dimensional geological model. All the research results presented above can make a significant instructing function for making reservoir development plan and improving recovery efficiency.

The analysis of 2D and 3D seismic data, drilled cores and well log data has resulted in a sequence stratigraphic framework of the Cretaceous Denglouku Formation in the Changling Depression in the underfilled Songliao Basin. The Cretaceous Denglouku Formation can be divided into four third-order sequences. Each sequence consists of two systems tracts: a transgressive systems tract and a highstand systems tract. A braided river delta is the main sedimentary facies in the study interval. These sequences were deposited in a back-arc rift basin during a transitional period from fault-dominant subsidence to downwarp subsidence. A sequence stratigraphic model is discussed based on the above interpretations. Typical unconformities are absent due to the absence of base level fall. Instead, maximum regressive surfaces, which are generally reworked by transgressive ravinement, act as the sequence boundaries. Each sequence bounded by these surfaces can be divided into two depositional units: a transgressive unit (TST) and normal regressive unit (HST). On land, a TST is characterized by a decreasing channel/floodplain ratio, and an HST is characterized by an increasing channel/floodplain ratio. Lakes are analogs to marine settings in which the shoreline moves forwards and backwards, and their strata show alternating retrogradation and progradation patterns. The results of this study may encourage the application of similar approaches to the correlation of successions within and beyond the Songliao Basin.

The Wei2 block of Weicheng oilfield is characterized by complicated structure mainly caused by high degree of fault development. Multiple reservoir types are found in this block and the reservoir heterogeneity is severe. The oil and gas reservoirs have already stepped into the stagnant stage of a great water-cut degree together with a rapid production decline rate. Thereby, both stabilizing the oil and gas production and optimizing adjustment for further exploitation make it urgent for geomodelers to build a useful model to predict the inter-well parameters and the distribution of the remaining oil and gas. A three-dimensional geological model established with the help of stochastic modeling technique may provide a perfect window and carrier for fine structure interpretation and reservoir heterogeneity description, compared with a traditional two-dimensional model. Hence, based on stratigraphical layering points, significant surfaces and fault points as well seismic interpretation, an integrated structure model is developed. Using the truncated Gaussian simulation and taking the existing geological maps as references, the sedimentary microfacies model was successfully constructed. Through the use of sequential Gaussian simulation method and the facies-controlled modeling method, the reservoir physical properties are populated. Meanwhile, the comparison between facies-controlled and non-facies-controlled property models indicates that the former is more loyal to previous researching and the representation of heterogeneity is ideal. Finally, the ideas of sample density and reserves fitting are proposed to evaluate the practicability and accuracy of the property models.

High-quality, large-area graphene films with few layers are synthesized on commercial nickel foams under optimal chemical vapor deposition conditions. The number of graphene layers is adjusted by varying the rate of the cooling process. It is found that the capacitive properties of graphene films are related to the number of graphene layers. Owing to the close attachment of graphene films on the nickel substrate and the low charge-transfer resistance, the specific capacitance of thinner graphene films is almost twice that of the thicker ones and remains stable up to 1000 cycles. These results illustrate the potential for developing high-performance graphene-based electrical energy storage devices.

To reduce or avoid some of the ambiguities in a heterogeneous reservoir, a fine three-dimensional model would be inevitably established with the application of geostatistical techniques. BD oilfield is a low-permeability fractured reservoir with many fracture types, which composes a multi-azimuthal fracture system, causing strong anisotropy and heterogeneity. Moreover, fracture provides not only accumulation space for oil and gas but also channels for migration of hydrocarbons and water dashing and thus plays a leading role in controlling BD reservoir production. With the continuous exploitation of oil in reservoir for more than 30 years, BD oilfield has currently stepped into high water cut stage, exposing many problems such as low oil recovery, poor exploitation stability, rapid oil production decline, and one-way water intrusion. Therefore, a detailed reservoir characterization, constructed to describe reservoir behavior under strong water drive in a well-developed fractured reservoir, is urgently needed. In this study, combined with three-dimensional geostatistical techniques, an accurate and efficient reservoir parameter model that occurs in a strong heterogeneous fractured reservoir has been constructed through stratigraphic correlation and sedimentary facies analysis. Hence, all the study presented above will be available for well location, remaining oil potential-tapping and oil recovery improvement during the later study work.

The silicon films as anode materials for lithium-ion batteries were fabricated by the cost-effective, high-throughput photosintering process. The thinner Si film (1.3 μm) exhibited larger storage capacity and better cyclability compared to the thicker one (4.2 μm) due to the close contact of the fused silicon nanoparticles with the substrate. Moreover, the addition of silver nanoparticles improved the conductivity of silicon film and facilitated the amorphous phase formation, resulting in enhanced capacity and cyclability. The photosintering approach highlights the advantage in the flexible and practicable manufacture and shows the promising prospects for developing high-performance Si-based anode materials.

Ethanol is considered as a potential alternative synthetic fuel to be used in automobiles or as a potential source of hydrogen for fuel cells. In this paper we first undertake a brief overview of the catalyst development for syngas conversion to C-2 oxygenates over Rh-based catalysts, mainly on the effects of various additives and supports on the activity and selectivity. Then we investigated the effects of carbon materials, which have been rarely studied as supports for Rh-based catalysts in this process. For example, rather well graphitized carbon black, very high surface area CMK-3 and activated carbon (AC) were compared to carbon nanotubes (CNTs), which exhibits a medium level surface area with well defined nanochannels. The CNT-supported catalyst shows a highest overall activity and yield of C-2 oxygenates compared to the other carbon-supported catalysts. The catalysts are characterized by N-2 adsorption-desorption, CO chemisorption, TEM, XRD and TPD. The graphitized structure combined with the tubular morphology of CNTs likely play an important role. (C) 2009 Elsevier B.V. All rights reserved.

Following our previous findings that confinement within carbon nanotubes (CNTs) can modify the redox properties of encapsulated iron oxides, we demonstrate here how this can affect the catalytic reactivity of iron catalysts in Fischer-Tropsch synthesis (FTS). The investigation, using in situ XRD under conditions close to the reaction conditions, reveals that the distribution of iron carbide and oxide phases is modulated in the CNT-confined system. The iron species encapsulated inside CNTs prefer to exist in a more reduced state, tending to form more iron carbides under the reaction conditions, which have been recognized to be essential to obtain high FTS activity. The relative ratio of the integral XRD peaks of iron carbide (Fe(x)C(y)) to oxide (FeO) is about 4.7 for the encapsulated iron catalyst in comparison to 2.4 for the iron catalyst dispersed on the outer walls of CNTs under the same conditions. This causes a remarkable modification of the catalytic performance. The yield of C5+ hydrocarbons over the encapsulated iron catalyst is twice that over iron catalyst outside CNTs and more than 6 times that over activated-carbon-supported iron catalyst. The catalytic activity enhancement is attributed to the effect of confinement of the iron catalyst within the CNT channels. As demonstrated by temperature-programmed reduction in H2 and in CO atmospheres, the reducibility of the iron species is significantly improved when they are confined. The ability to modify the redox properties via confinement in CNTs is expected to be of significance for many catalytic reactions, which are highly dependent on the redox state of the active components. Furthermore, diffusion and aggregation of the iron species through the reduction and reaction have been observed, but these are retarded inside CNTs due to the spatial restriction of the channels.

Keywords: Transmission tower, Uneven Settlement, Finite element analysis, Reinforcing scheme. Abstract. One leaning tower of 220 kV transmission line was taken as an example and a finite element model for the coupled tower-line system was established for investigating the effects of the uneven settlement on the transmission tower and line. The result shows that the bars of tower are compression-bending/tension-bending members which are under the combination action of bending moment and axial force. Von Mises equivalent stress value of Leg B is larger and the maximum stress value is 633MPa which is situated the root of tower leg, and it is larger than the yield strength of Q420 steel. Based on analyzing result, the reinforcing scheme was established.

Carbon nanotubes (CNTs) have well-defined hollow interiors and exhibit unusual mechanical and thermal stability as well as electron conductivity1. This opens intriguing possibilities to introduce other matter into the cavities2,3,4,5, which may lead to nanocomposite materials with interesting properties or behaviour different from the bulk6,7,8. Here, we report a striking enhancement of the catalytic activity of Rh particles confined inside nanotubes for the conversion of CO and H2 to ethanol. The overall formation rate of ethanol (30.0 mol mol−1Rh h−1) inside the nanotubes exceeds that on the outside of the nanotubes by more than an order of magnitude, although the latter is much more accessible. Such an effect with synergetic confinement has not been observed before in catalysis involving CNTs. We believe that our discovery may be of a quite general nature and could apply to many other processes. It is anticipated that this will motivate theoretical and experimental studies to further the fundamental understanding of the host–guest interaction within carbon and other nanotube systems.

Titania confined inside carbon nanotubes (CNTs) was synthesized using a restrained hydrolysis method. Raman spectra and magnetic measurements using a SQUID magnetometer suggested the formation of remarkable oxygen vacancies over the encapsulated TiO(2) in comparison with nanoparticles dispersed on the outer surface of CNTs, extending the photoresponse of TiO(2) from the UV to the visible-light region. The CNT-confined TiO(2) exhibited improved visible-light activity in the degradation of methylene blue (MB) relative to the outside titania and commercial P25, which is attributed to the modification of the electronic structure of TiO(2) induced by the unique confinement inside CNTs. These results provide further insight into the effect of confinement within CNTs, and the composites are expected to be promising for applications in visible-light photocatalysis.

Core–shell heterostructured Cu/Cu2O nanowires with a high aspect ratio were synthesized from Cu foam using a novel oxidation/reduction process. In situ XRD was used as an efficient tool to acquire phase transformation details during the temperature-programmed oxidation of Cu foam and the subsequent reduction process. Based on knowledge of the crucial phase transformation, optimal synthesis conditions for producing high-quality CuO and core–shell Cu/Cu2O nanowires were determined. In favor of efficient charge separation induced by the special core–shell heterostructure and the advanced three-dimensional spatial configuration, Cu/Cu2O nanowires exhibited superior visible-light activity in the degradation of methylene blue. The present study illustrates a novel strategy for fabricating efficiently core–shell heterostructured nanowires and provides the potential for developing their applications in electronic devices, for environmental remediation and in solar energy utilization fields.

The confinement within carbon nanotubes (CNTs) improves the electrochemical reversibility of CNT-confined MnO(2) nanoparticles and benefits their capacitive enhancement, which exhibit a specific capacitance of 225 F g(-1) for the composites and MnO(2) normalized capacitance as high as 1250 F g(-1).