With the green, circular, and low-carbon concept, eco-industrial parks are regarded as key drivers for maximizing environmental and economic benefits. Based on the panel data of 276 cities in China from 2007 to 2018, this paper regards the establishment of eco-industrial parks as a quasi-natural experiment, and employs the difference-in-differences method to test the impact of eco-industrial parks on urban haze pollution. We find that eco-industrial parks significantly reduce urban haze pollution and the conclusion holds with robustness tests. Heterogeneity analysis shows that the effect of eco-industrial parks on haze pollution is more pronounced in eastern and resource-based cities. Finally, mechanism analysis indicates that eco-industrial parks reduce urban haze pollution mainly by promoting technological innovation, upgrading industrial structure, and strengthening urban environmental regulations.

Previous work suggests that the arrangement of elements in an obstruction may influence the bulk flow velocity through the obstruction, but the physical mechanisms for this influence are not yet clear. This is the motivation for this study, where direct numerical simulation is used to investigate flow through an array of cylinders at a resolution sufficient to observe interactions between wakes of individual elements. The arrangement is altered by varying the gap ratio $G/d$ (1.2 – 18, G is the distance between two adjacent cylinders, d is the cylinder diameter), array-to-element diameter ratio $D/d$ (3.6 – 200, D is the array diameter), and incident flow angle ($0^{\circ} - 30^{\circ}$). Depending on the element arrangement, it is found that the average root-mean-square lift and drag coefficients can vary by an order of magnitude, whilst the average time-mean drag coefficient of individual cylinders ($\overline{C_{d}}$), and the bulk velocity are found to vary by up to $50\,\%$ and a factor of 2, respectively. These arrangement effects are a consequence of the variation in flow and drag characteristics of individual cylinders within the array. The arrangement effects become most critical in the intermediate range of flow blockage parameter $\mathit{\Gamma_{D}^{\prime}} = 0.5-1.5$ ($\mathit{\Gamma_{D}^{\prime}}=\overline{C_{d}}aD/(1-\phi)$, where a is frontal element area per unit volume, and $\phi$ is solid volume fraction), due to the high variability in element-scale flow characteristics. Across the full range of arrangements modelled, it is confirmed that the bulk velocity is governed by flow blockage parameter but only if the drag coefficient incorporates arrangement effects. Using these results, this paper proposes a framework for describing and predicting flow through an array across a variety of arrangements.

Understanding settling motion of coral grains is important in terms of protection of coral reef systems and resotoration of the associated ecosystems. In this paper, a series of laboratory experiments was conducted to investigate the settling motion, using optical microscopy to measure shape parameters of coral grains and the particle-filtering-based object tracking to reconstruct the three-dimensional trajectory. Three characteristic descent regimes, namely, tumbling, chaotic and fluttering, are classified based on the three-dimensional trajectory, the spiral radius variation and the velocity spectrum. It is demonstrated that if one randomly picks up one coral grain, then the probabilities of occurrence of the three regimes are approximately $26\,\%$, $42\,\%$ and $32\,\%$, respectively. We have shown that first, the dimensionless settling velocity generally increases with the non-dimensional diameter and Corey shape factor and second, the drag coefficient generally decreases with the Reynolds number and Corey shape factor. Based on this, the applicability of existing models on predicting settling velocity and drag coefficient for coral grains is demonstrated further. Finally, we have proposed extended models for predicting the settling velocity. This study contributes to better understanding of settling motion and improves our predictive capacity of settling velocity for coral grains with complex geometry.

Although there is a range of approaches for classifying the wake structure behind an array of obstacles, these approaches provide inconsistent results across different array systems. This motivates the present study to integrate and reconcile these approaches into one that is consistent across different systems. This new, transferable classification approach is based on the dimensionless flow blockage of the array and the wake stability parameter. To demonstrate this approach, a series of laboratory experiments was conducted to characterise the wake structure behind an array of emergent cylinders across a practically relevant parameter space that has not previously been explored. Two arrays with the same values of flow blockage and wake stability parameters but different sizes display the same wake structure, demonstrating the controlling influence of these two parameters on the wake structure. This approach classifies four different wake structures, which are distinct in that they display differences in instantaneous and time-averaged flow fields, temporal velocity oscillations, shear layer growth and the length of the steady wake region. The dependence of the wake structure on the two parameters is a consequence of (i) the controlling influence of blockage on the fraction of incident flow passing through the array and (ii) the ability of shallowness to suppress wake instabilities and, to a lesser extent, also influence the velocity through the array. This paper provides a predictive framework for the wake structure based on knowledge of the array geometry, and the depth and velocity of incident flow across the entire relevant practical parameter space.

Hydroxymetal-clay complexes, which contain reactive surface hydroxyl groups, have a strong affinity for both heavy-metal cations and oxyanions and hence can serve as efficient sorbents for ionic contaminants. The co-sorptive behavior of heavy-metal cations and oxyanions on the surface of hydroxymetal-clay complexes is not well understood, however. The objective of the present investigation was to help bridge that gap by determining the feasibility of co-sorbing Cd cations and phosphate from aqueous solution to a hydroxyiron-montmorillonite complex (HyFe-mont). A montmorillonite-rich clay from Inner Mongolia, China, was the starting material. The results showed that Cd and phosphate could be sorbed, simultaneously and synergistically, to HyFe-mont without a change in solution pH. Similarly, when phosphate was sorbed before Cd, the sorption capacities were comparable to those obtained in the simultaneous sorption experiment, and the solution pH did not change.When Cd was pre-sorbed, however, the subsequent sorption of both Cd and phosphate decreased as did solution pH. X-ray photoelectron spectroscopy (XPS) indicated that the binding energies of P2p, Cd3/2, and Cd5/2 were of similar magnitude for both the simultaneous sorption system and the phosphate pre-sorbed system. In addition, the single Cd and Cd pre-sorbed systems had similar Cd3/2 and Cd5/2 binding energies. The combined sorption and XPS results suggested that sorbed phosphate and Cd formed P-bridged ternary complexes on the HyFe-mont surface, contributing to the synergistic uptake of the contaminants in the simultaneous sorption system.

Pyrophyllite is an important layered phyllosilicate material that is used in many fields due to its beneficial physicochemical and mechanical properties. Due to the presence of multiple defects in pyrophyllite, an in-depth investigation was conducted using density functional theory to explore the effects of Na(I), K(I), Mg(II), Ca(II) and Fe(II) doping on the atomic structure, electronic properties and mechanical characteristics of pyrophyllite. The results demonstrated that, among the studied defects, K(I) doping had the most pronounced effects on the lattice constants and bonding lengths of pyrophyllite, while the least significant effects were observed in the case of Fe(II) doping. Moreover, the partial and total densities of states and band structures of the five kinds of doped pyrophyllite also changed significantly due to the redistribution of electrons. Finally, the elastic constants of the doped pyrophyllite were lower than that of the undoped pyrophyllite. Doping with Na(I), K(I), Mg(II), Ca(II) and Fe(II) reduced the deformation resistance, stiffness and elastic wave velocity but increased the degree of anisotropy in pyrophyllite. The observed effects on the mechanical properties of pyrophyllite followed the order: Mg(II) > Fe(II) > Ca(II) >K(I) > Na(I).

The oscillatory Kelvin–Helmholtz (K–H) instability of a planar liquid sheet was experimentally investigated in the presence of an axial oscillating gas flow. An experimental system was initiated to study the oscillatory K–H instability. The surface wave growth rates were measured and compared with theoretical results obtained using the authors’ early linear method. Furthermore, in a larger parameter range experimentally studied, it is interesting that there are four different unstable modes: first disordered mode (FDM), second disordered mode (SDM), K–H harmonic unstable mode (KHH) and K–H subharmonic unstable mode (KHS). These unstable modes are determined by the oscillating amplitude, oscillating frequency and liquid inertia force. The frequencies of KHH are equal to the oscillating frequency; the frequency of KHS equals half the oscillating frequency, while the frequencies of FDM and SDM are irregular. By considering the mechanism of instability, the instability regime maps on the relative Weber number versus liquid Weber number (Werel–Wel) and the Weber number ratio versus the oscillating frequency (Werel/Wel–$\varOmega$s2) were plotted. Among these four modes, KHS is the most unexpected: the frequency of this mode is not equal to the oscillating frequency, but the surface wave can also couple with the oscillating gas flow. Linear instability theory was applied to divide the parameter range between the different unstable modes. According to linear instability theory, K–H and parametric unstable regions both exist. However, note that all four modes (KHH, KHS, FDM and SDM) corresponded primarily to the K–H unstable region obtained from the theoretical analysis. Nevertheless, the parametric unstable mode was also observed when the oscillating frequency and amplitude were relatively low, and the liquid inertia force was relatively high. The surface wave amplitude was small but regular, and the evolution of this wave was similar to that of Faraday waves. The wave oscillating frequency was half that of the surface wave.

A novel low-profile two-arm backfire tapered cone helical antenna for telemetry tracking and command (TT&C) is introduced theoretically and experimentally in this paper. Compared with the conventional helical antenna, this design has a substantial decrease in its height and an increase both in its half power beamwidth (HPBW) and 3-dB axial ratio beamwidth by replacing the uniform structure with two tapered cone structures. It provides a maximum gain of 5.1 dBi, an excellent circular polarization radiation over a wide angular range of more than 124°, a 3-dB axial ratio bandwidth of 18.8%, a wide HPBW of more than 125°, and nearly equal E- and H- plane far-field patterns with high degree of axial symmetry over S-band (2–2.3 GHz). These excellent radiation characteristics with an endurable and compact structure make it an attractive candidate for TT&C application in microsatellite system, where the installation envelope and space for antenna are extremely limited.

How do subnational agents exercise policy discretion in the social welfare sphere? To what extent do they do so as a result of various bureaucratic and fiscal incentives? The literature has documented several explanatory frameworks in the context of China that predominantly focus on the realm of developmental policies. Owing to the salient characteristics of the social policy arena, local adaptation of centrally designed policies may operate on distinctive logics. This study synthesizes the recent scholarship on subnational social policymaking and explains the significant interregional disparities in China's de facto urban poverty line – the eligibility standard of the urban minimum livelihood guarantee scheme, or dibao. Five research hypotheses are formulated for empirical examination: fiscal power effect, population effect, fiscal dependency effect, province effect and neighbour effect. Quantitative analysis of provincial-level panel data largely endorses the hypotheses. The remarkable subnational variations in dibao standards are explained by a salient constellation of fiscal and political factors that are embedded within the country's complex intergovernmental relations and fiscal arrangements. Both a race-to-the-top and a race-to-the-bottom may be fostered by distinctive mechanisms. The unique role of provincial governments as intermediary agents within China's political apparatus is illuminated in the social policy arena.

Characterizing the whole genetic architecture of drought tolerance (DT) is a persistent challenge for the breeders. Here we developed a half-sib population comprising of 404 lines of two recombinant inbred line (RIL) populations with M8206 as the joint parent (M8206 × TongShan and ZhengYang × M8206) and tested for its DT under sand culture. The population was sequenced using restriction-site-associated DNA sequencing filtered with minor allele frequency ≥0.01; 55,936 single nucleotide polymorphisms (SNPs) were obtained and assembled into 6137 SNPLDBs (SNP linkage disequilibrium blocks). The restricted two-stage multi-locus genome-wide association analysis characterized with error and false-positive control identified 40 QTLs with 93 alleles on an average of 34.75% of the phenotypic variance (PV) collectively for relative root length (RRL) and relative shoot length (RSL) that served as potential DT indicators. Among these, eight loci corresponded to previously reported QTLs, whereas 32 loci were therefore novel. The identified QTLs with their corresponding alleles for RRL and RSL were organized into QTL-allele matrices, depicting the comprehensive DT genetic architecture of the three parents/half-sib population. From the matrices, we predicted the possible best/optimal genotype with weighted average value (WAV) 1.553 over two indicators, while for the top 10 single crosses among RILs with 95th percentile WAV was 1.218–1.257, transgressive over the parents (0.693–0.794) yet much less than 1.553. From the detected QTL-allele system, 65 potential candidate genes collectively for both indicators explaining on an average of 24.41% PV were annotated and χ2-tested as a DT candidate gene system involving nine biological processes.