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Innovation is generally regarded as critical to long-run economic growth. Recent work, at different spatial scales, suggests economies that develop more complex technologies that are related to their existing knowledge stocks enjoy a growth premium. Thus, “smarter” forms of innovation may accelerate growth. These claims are examined using Chinese patent data distributed across 286 cities over the period 1991–2015. Fixed-effects panel models report that city-level GDP growth in China has a significant and positive relationship with diversification into more related and complex technologies, after controlling for the overall pace of innovation and other covariates. Robustness checks focusing on spatial autocorrelation and endogeneity affirm the core findings.

Economies producing more complex products tend to be wealthier and grow more quickly. Therefore, a key issue for cities around the world is to develop new specializations into more complex industries. In China, local governments tend to use industrial land subsidy as a policy tool to attract new firms in desired industries and promote industrial growth. However, relatively little is known about the impact of this policy tool on the economic complexity of Chinese cities. Drawing upon the recent literature on the principle of relatedness and economic complexity, this paper investigates the impact of this industrial land policy (ILP) on the diversification of Chinese cities into more complex industries. The empirical results support our hypothesis that those cities providing higher intensity of land subsidy are more likely to enter new industries, in particular the most complex ones.

Core-shell micro-spheres (MS) with both negative and positive charges in the core and only negative charges in the shell were developed as adaptive plugging agents for in-depth conformance control for enhanced oil recovery. The MS were designed to propagate deeply into the reservoir due to the small particle size and electrostatic repulsion between the MS and the sandstone at the initial stage of injection and form aggregates by electrostatic attraction between the cores with mixed charges when the shells degraded at a given time during transportation, leading to an effective plugging of the highly permeable layers with low residual oil saturation. The self-assembling and plugging behaviors of the MS have been studied by Monte Carlo simulation. The results show that charge density (Dcharge), fraction of positive charge (Fp), MS concentration, temperature, and salinity are the key factors influencing the self-assembling behaviors. The electrostatic interaction would become stronger with the increase in Dcharge when it is larger than 0.5. The MS are more likely to form aggregates when Fp approaches 0.5. The higher the concentration of the MS, the stronger the electrostatic interaction between the MS. In addition, electrostatic interactions between the MS become stronger with the increase in temperature and decrease in salinity. Simulation results prove that the MS with mixed charges can effectively and adaptively plug highly permeable layers with low residual oil saturation through self-assembling by combination of electrostatic interactions along with physical bridging, leading to the improvement of oil recovery. Furthermore, block charge distribution will be helpful for the MS with mixed charges to form larger aggregates than that of the random mode to effectively plug the highly permeable layers.

Accuracy is a key factor in high-resolution remote sensing and photogrammetry. The factors that affect accuracy are imaging system errors and data processing errors. Due to the complexity of aerial camera errors, this paper focuses on the design of digital aerial camera systems and the means to reduce system error and data processing inefficiencies. There are many kinds of digital aerial camera systems at present; however, these systems lack a unified physical model, which ultimately leads to more complicated designs and multi-camera modes. Such a system is complex and costly, as it is easily affected by factors such as vibration and temperature. Thus, the installed accuracy can only reach the millimeter level. Here, we describe a unified physical structure for a digital aerial camera that imitates an out-of-field multi-charge-coupled device (CCD), an in-field multi-CCD, and once-imaging and twice-imaging digital camera systems. This model is referred to as the variable baseline-height ratio spatiotemporal model. The variable ratio allows the opto-mechanical spatial parameters to be linked with height accuracy, thus providing a connection to the surface elevation. The twice-imaging digital camera prototype system and the wideband limb imaging spectrometer provide a transformation prototype from the current multi-rigid once-imaging aerial camera to a single rigid structure. Thus, our research lays a theoretical foundation and prototype references for the construction and industrialization of digital aerial systems.

Among existing approaches to holonomic quantum computing, the adiabatic holonomic quantum gates (HQGs) suffer errors due to decoherence, while the non-adiabatic HQGs either require additional Hilbert spaces or are difficult to scale. Here, we report a systematic, scalable approach based on dynamical invariants to realize HQGs without using additional Hilbert spaces. While presenting the theoretical framework of our approach, we design and experimentally evaluate single-qubit and two-qubits HQGs for the nuclear magnetic resonance system. The single-qubit gates acquire average fidelity 0.9972 by randomized benchmarking, and the controlled-NOT gate acquires fidelity 0.9782 by quantum process tomography. Our approach is also platform-independent, and thus may open a way to large-scale holonomic quantum computation., Comment: 9 pages, 3 figures

Different tougheners including methyl methacrylate-butadiene-styrene terpolymer (MBS, core-shell type), maleic anhydride (MAH) grafted ethylene-octene copolymer (EOM), and MAH grafted polyethylene wax (PEM) were investigated for toughening the polycarbonate (PC) composites reinforced by short carbon fiber (SCF) and flake graphene (FG). The effects of tougheners on the preparation, thermal conductivity and mechanical properties of PC composites were studied. Scanning electron microscopy was used for characterizing the impact fracture surfaces of the composites. The results showed that introducing tougheners into the carbon reinforced PC composites was beneficial to improving the processability, and PEM was more effective than EOM and MBS. Meanwhile, the through-thickness and the in-plan thermal conductivity decreased to some degree due to the isolated island effects of tougheners. Moreover, the brittle PC composites with high flexural stress could be easily toughened by tougheners. In contrast, PEM had better toughening function than EOM and MBS, and correspondingly, the stiffness of the composites was the lowest for the PEM toughened systems. The fractography revealed that dense and uniformly distributed carbon fillers dispersed in matrix PC and circular cavities coexisted in the composites. The naked fiber length gradually increased as the ductility of composite materials improved.

Drawing upon a panel dataset on China's state‐owned construction land supply at the prefecture level, this paper adopts the spatial panel data model to investigate the existence of spatial dependence in the mechanisms behind China's urban land expansion from 2004 to 2014. The empirical results show that China's urban land expansion has been mainly influenced by a quadruple process of urbanization, industrialization, globalization and decentralization. The strong existence of spatial dependence in China's urban land expansion can be reflected by the significant coefficient estimates of the spatial lags of both the dependent variable and independent variables. Este articulo emplea un conjunto de datos de panel sobre la oferta de terrenos para la construccion de propiedad estatal de China a nivel de prefectura, con el objeto de adoptar el modelo de datos de panel espaciales para investigar la existencia de una dependencia espacial en los mecanismos que rigen la expansion del suelo urbano de China desde 2004 hasta 2014. Los resultados empiricos muestran que la expansion del suelo urbano de China se ha visto influenciada principalmente por un proceso cuadruple de urbanizacion, industrializacion, globalizacion y descentralizacion. La fuerte existencia de dependencia espacial en la expansion del suelo urbano en China se puede reflejar en las estimaciones significativas de los coeficientes de los retardos espaciales de la variable dependiente y de las variables independientes. 本稿では、中国の県レベルでの建設用地として供給される国有地に関するパネルデータを利用し、空間的パネルデータモデルを用いて、2004年~2014年の中国における都市部の土地拡大のメカニズムにおける空間依存性の存在を調査する。実証研究の結果は、中国都市部の土地拡大はこれまで、主に、都市化、産業化、グローバル化、地方分散化の4つの過程の影響を受けてきている。中国都市部の土地拡大における空間的依存性の大きな存在は、独立変数と従属変数の両方の空間ラグの有意な係数推定値に反映される。

Bio-based zwitterionic surfactants have received increasing attention owing to their structural diversity and good interfacial activity. Therefore, understanding the relationship between the structure of bio-based zwitterionic surfactants and interfacial behaviors has significance for its industrial applications. In this study, molecular dynamics simulation was employed to investigate the interfacial behaviors of bio-based zwitterionic surfactants (BZS) with seven structures at the air/water interface. The four of them were isomers of BZS, in which the phenyl groups were located at the 7-, 10-, 13-, and 16- carbon atom of the octadecanoyl group. The other three were the homologues of 10B, and were different in the structures of hydrophilic groups. The structure-property relationship was demonstrated by the structure of surfactant monolayer, the overall arrangement of surfactant molecules at the interface, and the dynamic properties of binding pairs between surfactant and water/cations. The results showed that waved monolayers were formed when the phenyl group located at the 7- carbon atom of the hydrophobic tail of BZS, and there were more hydration water and cations surrounding the hydrophilic group of surfactants. As for the surfactants with the phenyl group located at 16- of the hydrophobic tail of BZS, molecules were arranged more perpendicular at the interface and formed a flat monolayer and construct stable binding pairs with water and cations. Morphology of monolayer and molecular orientation were independent of the change in structure of headgroup, but surfactant with less methylene on the hydrophilic group had the less steric hindrance, which induced more hydration water, more neighboring surfactants, and more stable of binding pairs between COO- and water.

Ionic alkoxy-based surfactants recently attract more attentions because they possess advantages of both nonionic and anionic surfactants, and surfactant structure is the key factor affecting the interfacial property and salt tolerance of ionic alkoxy-based surfactant. In the present study, carboxylated nonylphenol ethoxylate surfactant (NPEOnC, n = 2, 4, and 7) at n-decane/water interface has been studied using molecular dynamics simulation in the absence and in the presence of NaCl with different concentrations. The interfacial activity in reducing interfacial tension and salt tolerance of NPEOnC were investigated and the effect of numbers of ethoxy unit were quantified. The interfacial activities of NPEOnC were demonstrated by the arrangement of surfactant monolayer, the structures of n-decane/water interface, and the interfacial tensions. Salt tolerance of NPEOnC were estimated by the bound pairs between surfactant and water as well as those between surfactant and Na+, especially the structural relaxation dynamics of those bound pairs. Results showed that NPEO7C exhibited the highest activity in lowering the interfacial tension of n-decane/water, and kept the interfacial activity in the presence of NaCl. Carboxyl groups were the predominant groups in binding with Na+, and ethoxy segment within NPEO4C and NPEO7C were the governing groups in being solvated with water. Moreover, the structural relaxations of bound pairs between oxygen within ethoxy segment and water/Na+ were much slower than those between oxygen within carboxyl group and water/Na+, which resulted in the higher salt tolerance of NPEOnC with more ethoxy units.

The paper presents a new method for the change detection of built-up areas based on ensemble learning. The method selects the feature generation part of VGG network to replace the encoder of UNet network, and makes full use of the advantages of VGG network in feature interpretation to construct a new network VGG-UNet, so as to improve the information extraction accuracy of built-up areas. First, the slice sample sets containing built-up areas and non-built-up areas were established. Secondly, the model was trained and tested to obtain several optimal models with high precision. Thirdly, these optimal models were used to extract the change information of built-up areas in the experimental area. Finally, the results were ensemble optimized and the accuracy was verified by comparing with the field measurements. The experimental results in Xinjiang demonstrate the advantages, feasibility and reliability of the proposed method. Moreover, the ensemble optimization of multiple model results can further improve the change detection accuracy of built-up areas.

A novel binary system consisting of a cationic surfactant and a counter ion that can form wormlike micelles with high viscosity is proposed. Wormlike micelles based on 2-hydroxyethyl dimethyl hexadecyl ammonium acetate (HDMHA) and sodium salicylate (NaSal) as counter ion were detected via both cryo-TEM and SANS in dilute solution. Moreover, rheological measurements of the HDMHA/NaSal system were conducted as a function of temperatures. The results demonstrate the formation of long elongated wormlike micelles in dilute solution at temperatures that exceed 60 °C.

Knowledge polycentricity and the evolving Yangtze River Delta megalopolis. Regional Studies. Inspired by the two defining but often overlooked features of megalopolises as ‘hinges’ and ‘incubators’, this paper presents a multi-scalar and dynamic analysis of the knowledge polycentricity of China’s Yangtze River Delta Region. Using data on publications and co-publications from 2000 to 2014, the results show that the structures of knowledge production and knowledge collaboration within and beyond the region have, to differing degrees, become more polycentric. Whereas the region has acted as an ‘incubator’ of knowledge at the megalopolitan scale, its ‘hinge’ role in knowledge collaboration has been mainly played at the national scale.

The surfactant structure–performance relationship and application properties in enhanced oil recovery (EOR) for binary mixtures of anionic and cationic surfactants are presented and discussed. A polyoxyethylene ether carboxylate anionic surfactant was blended with a quaternary ammonium chloride cationic surfactant and tested for a high-temperature, low-salinity, and high-hardness condition as found in an oil reservoir. These mixtures were tailored by phase behavior tests to form optimal microemulsions with normal octane (n-C8) and crude oil having an API gravity of 48.05°. The ethoxy number of the polyoxyethylene carboxylate anionic surfactant and the chain length of the cationic surfactant were tuned to find an optimal surfactant blend. Interfacial tensions with n-C8 and with crude oil were measured. Synergism between anionic and cationic surfactants was indicated by surface tension measurement, CMC determination, calculation of surface excess concentrations and area per molecule of individual surfactants and their mixtures. Molecular interactions of anionic and cationic surfactants in mixed monolayers and aggregates were calculated by using regular solution theory to find molecular interaction parameters β σ and β M . Morphologies of surfactant solutions were studied by cryogenic TEM. The use of binary mixtures of anionic/cationic surfactants significantly broadens the scope of application for conventional chemical EOR methods.

Traditional method of forecasting electricity consumption based only on GDP was sometimes ineffective. In this paper, urbanisation rate (UR) was introduced as an additional predictor to improve the electricity demand forecast in China at provincial scale, which was previously based only on GDP. Historical data of Shaanxi province from 2000 to 2013 was collected and used as case study. Four regression models were proposed and GDP, UR, and electricity consumption (EC) were used to establish the parameters in each model. The model with least average error of hypothetical forecast results in the latest three years was selected as the optimal forecast model. This optimal model divides total EC into four parts, of which forecasts can be made separately. It was found that GDP was only better correlated than UR on household EC, whilst UR was better on the three sectors of industries. It was concluded that UR is a valid predictor to forecast electricity demand at provincial level in China nowadays. Being provided the planned value of GDP and UR from the government, EC in 2015 were forecasted as 131.3 GWh.

© 2015 The Author(s). Papers in Regional Science © 2015 RSAI Drawing upon township-level data on high-tech firms of Nanjing, China, this paper adopts a spatial econometric approach to examining the existence of spatial dependence and heterogeneity in the location processes of high-tech firms. The results show that some locational determinants of neighbouring townships exert significant impacts on the attractiveness of a certain township for high-tech firms. Besides, the marginal effects of some locational determinants are found to vary across space. In general, these results point to the need to account for both inter-territorial spillovers and cross-spatial variance in the investigation of factors that influence high-tech firm location.

While many studies find that air pollution has been generally related with natural factors and anthropogenic activities, relatively little attention has been paid to exploring the impact of urban spatial structure on air pollution. This paper investigates the relationship between urban spatial structure and PM2.5 concentrations by drawing upon a panel dataset covering 286 Chinese cities during the 2001–2016 period. We measure two dimensions of urban spatial structure by using the LandScan High Resolution Global Population Dataset. The polycentricity-monocentricity dimension reflects to what extent population is distributed in a single center or across a number of subcenters. The concentration-dispersion dimension represents to what extent population is clustered in urban centers. By controlling for per capita GDP, population density, and the employment share of the secondary industry, our empirical results based on two-way fixed panel regression models find positive relationships between polycentricity, dispersion, and PM2.5 concentrations of Chinese cities. Other things being equal, an increase in the degrees of polycentricity and dispersion by 0.1 would lead to a rise in PM2.5 concentration by 0.1996 μg/m3 and 0.4063 μg/m3 respectively. Moreover, we find that the impact of polycentricity on PM2.5 concentrations is heterogeneous across cities. For cities with higher per capita GDP (>5200 US$) or a higher employment share of the secondary industry (>55.37%), a polycentric distribution of population is also expected to reduce PM2.5 concentrations. The results suggest that the planning of polycentric urban structure pursued by many Chinese local governments should be cautiously rethought.

While China’s unprecedented urbanization process has caused substantial changes in urban spatial structure of its cities, relatively less is known about the nature and form of such changes. This paper provides a descriptive analysis of the evolution of urban spatial structure of 286 Chinese cities during the 2001–2016 period. Drawing upon the fine-grained LandScan population dataset and with the use of exploratory spatial data analysis techniques, we develop an approach to identifying population centers and measuring urban spatial structure from the dimensions of polycentricity and dispersion. Specifically, a city is considered more polycentric when it has a more balanced distribution of population between its main center and subcenter(s), while it is considered less dispersed when it has a higher share of population living in its urban centers. The empirical results which are robust based on different definitions of population centers show that urban spatial structure of Chinese cities has generally evolved towards concentration (i.e., less dispersed) and decentralization (i.e., more polycentric), with the former trend being relatively stronger than the latter one. Furthermore, we find that the evolution patterns differ across cities with different original types of urban spatial structure. Cities with relatively higher degrees of dispersion are more likely to change their urban spatial structure. Moreover, we find that cities which have changed their urban spatial structure tend to have higher population and per capita GDP growth than those that have not changed. Significant differences in population and economic productivity growth are also found to exist across cities with different evolution patterns of urban spatial structure.

The effect of cellulose acetate butyrate (CAB) on the crystallization kinetics of polylactic acid (PLA) has been investigated by means of differential scanning calorimetry (DSC), polarized optical microscopy (POM) and scanning electron microscopy (SEM). CAB is essentially immiscible with PLA, as CAB spherical particles with average diameters in the range of 140–185 nm dispersed uniformly in PLA matrix. The incorporation of CAB effectively reduces the crystallization rate of PLA even at a low loading of 0.2 wt%. Moreover, it is particularly interesting to find a critical CAB content (about 5 wt%) which further increase in CAB concentration doesn’t bring significant influence on the PLA crystallization rate. Combined with the results of POM, SEM, DSC and selective dissolving experiment, it is proposed that the coating of CAB on the nuclei which enhanced by the nano-scaled CAB structure could strongly inhibit the nucleation, and thereby reduce the overall crystallization rates of PLA.

World's human dynamics can be parameterized with metrics that explain the current model of economic growth and its sustainability. Changes in the world's human dynamics are crucial for understanding the current state of the world, which is faced with increasing challenges related to globalization. In this paper, we propose to analyze the shifting locations of centers of gravity of four basic global indicators (these are Gross Domestic Product, carbon dioxide emissions, population, and urban population) for the period 1960–2016. The spatial locations of the respective centers of gravity (one per year) draw some traces that explain, at least partially, relevant changes on different world's human dynamics at a global level. These traces and dynamics are further discussed. In addition, these traces are fundamental for predicting upcoming trends for the next few years. Results shown here may help political leaders and policymakers for solving upcoming and future global challenges related to the current economic system and its impact on the environment.

We extend the twisted gauge theory model of topological orders in three spatial dimensions to the case where the three spaces have two dimensional boundaries. We achieve this by systematically constructing the boundary Hamiltonians that are compatible with the bulk Hamiltonian. Given the bulk Hamiltonian defined by a gauge group G and a four-cocycle ω in the fourth cohomology group of G over U(1), we construct a gapped boundary Hamiltonian using {K, α}, with a subgroup K ⊆ G and a 3-cochain α of K over U(1), which satisfies the generalized Frobenius condition. The Hamiltonian is invariant under the topological renormalization group flow (via Pachner moves). Each solution {K, α} to the generalized Frobenius condition specifies a gapped boundary condition. We derive a closed-form formula of the ground state degeneracy of the model on a three-cylinder, which can be naturally generalized to three-spaces with more boundaries. We also derive the explicit ground-state wavefunction of the model on a three-ball. The ground state degeneracy and ground-state wavefunction are both presented solely in terms of the input data of the model, namely, {G, ω, K, α}.

Three-dimensional geological modelling of coal mines is critical to the sustainable development of the mining industry. On the basis of comprehensively analyzing 3D geological modelling methods, according to the available data of mine such as geological terrain maps, cross-sections and boreholes, we present a 3D modelling method by integrating ArcGIS and 3D GeoModeller. Our motivation is to integrate the advantages of both software modules in processing, converting, integrating and transferring geological information. Special attention has been given to the data structure and processing flow. We build a 3D geological model of the Xieqiao coal mine and successfully extract the geological framework of the strata in the 11118 workface, which is consistent with that of the actual explored geology.

The effect of tin on the structure, acidity, and water adsorption property of Nb2O5/α-Al2O3 catalyst and on this catalyst's performance for ethylene oxide (EO) hydration were studied by XRD, Raman spectroscopy, NH3-TPD, IR of pyridine and of H2O adsorption, and catalytic tests. Characterization results revealed that the density of acidic sites decreased with the addition of tin and with increasing Sn/Nb ratio in the cases studied, whereas the acidity exhibited minimum strength at Sn/Nb=0.08Sn/Nb=0.08. The IR of water adsorption indicated that addition of tin significantly enhanced the water adsorption property of the catalyst. The catalytic tests revealed that monoethylene glycol (MEG) selectivity increased from 89.8% of the Nb2O5/α-Al2O3 catalyst to 94.0% of the tin-promoted catalyst maintaining the EO conversion at 99.7%, and the catalyst exhibited excellent stability. The enhanced water adsorption property of the tin-promoted catalyst is proposed to be responsible for the significant improvement in MEG selectivity.

Effect of MgAl 2 O 4 on the structure, acidity as well as the catalytic performance of Nb 2 O 5 /α-Al 2 O 3 catalyst for ethylene oxide hydration was studied using IR, XRD, NH 3 -TPD, CO 2 -TPD and catalytic reaction. Modification of α-Al 2 O 3 support with MgAl 2 O 4 led to an increase in both basicity and mechanical strength of the support. As a result, the density and strength of the acidity of the niobium oxide catalyst supported on the MgAl 2 O 4 modified α-Al 2 O 3 reduced in comparison with that supported on the pure α-Al 2 O 3 . The acidity of 10% Nb 2 O 5 /MgAl 2 O 4 /α-Al 2 O 3 decreased with increasing loading of MgAl 2 O 4 . Catalytic test showed that EO conversion decreased monotonously with increasing MgAl 2 O 4 loading, whereas the selectivity to MEG exhibited a maximum of 90.6% at MgAl 2 O 4 loading of 2.23%. In terms of MEG yield, optimal MgAl 2 O 4 loading should be around 2%. Durability test demonstrated that 10% Nb 2 O 5 /MgAl 2 O 4 /α-Al 2 O 3 catalyst exhibited excellent stability within 1000 h time-on-stream.

Niobium oxide (Nb2O5) supported on α-alumina (α-Al2O3) prepared by impregnation was studied for hydration of ethylene oxide. The effects of niobium oxide loadings, calcination temperature and molar ratio of water to ethylene oxide (EO) on the reaction performance were investigated. The structure and acidity of the catalysts were characterized by using X-ray diffraction (XRD), differential thermal analysis (DTA)-thermogravimetric (TG) and infrared (IR) of pyridine adsorption. A durability test of niobic acid and Nb2O5/α-Al2O3 catalyst was carried out over a period of 1000 h. It was found that Nb2O5/α-Al2O3 demonstrated very high activity and selectivity for hydration of ethylene oxide to monoethylene glycol (MEG) under mild conditions. Compared with the result of non-catalytic reactions, the conversion of ethylene oxide was increased from 34 to 99.8% on keeping monoethylene glycol selectivity almost unchanged when the hydration was carried out over 10 wt.%Nb2O5/α-Al2O3 catalyst. The yield of monoethylene glycol over Nb2O5/α-Al2O3 was higher than that obtained over other solid acid catalysts. Moreover, the supported niobia catalyst demonstrated excellent stability and no deactivation was observed within 1000 h of time-on-stream.