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The existing conventional traffic flow models aims to simulate human-driven following vehicles in real world. In this era of emerging transport solutions, controlling or intervening traffic flow to achieve high fuel efficiency along with good driving safety and travel efficiency becomes a reality. As such, it is worth exploring the possibility of developing eco-driving models to optimise vehicle movements for fuel consumption minimisation, while maintaining safety and efficiency. In this study, we propose a modified genetic algorithm (GA) based calibration method that enables the calibrated parametric traffic flow (car following) models to simulate or control vehicles in an eco-driving manner. By developing a novel objective function for the GA method based on the widely-used VT-Micro fuel consumption model, the proposed method can calibrate model parameters towards improving fuel efficiency. Besides, by subtly using heavy fuel consumptions as a surrogate index to represent low travel efficiency or dangerous driving strategies, the modified GA method with the novel objective function can guide the calibrated model towards achieving complete eco-driving requirements. Experimental simulation results further indicate that traffic flow models calibrated by the modified GA-based method can also alleviate traffic disturbances and oscillations in a more effective manner.

In this paper, a Ni coating was deposited on the surface of the A356 aluminum alloy by high velocity oxygen fuel spraying to improve the performance of the AZ91D magnesium/A356 aluminum bimetal prepared by a compound casting. The effects of the Ni coating as well as its thickness on microstructure and mechanical properties of the AZ91D/A356 bimetal were systematically researched for the first time. Results demonstrated that the Ni coating and its thickness had a significant effect on the interfacial phase compositions and mechanical properties of the AZ91D/A356 bimetal. The 10µm's Ni coating cannot prevent the generation of the Al-Mg intermetallic compounds (IMCs) at the interface zone of the AZ91D/A356 bimetal, while the Ni coating with the thickness of 45 µm and 190 µm can avoid the formation of the Al-Mg IMCs. When the Ni coating was 45 µm, the Ni coating disappeared and transformed into Mg-Mg2Ni eutectic structures+Ni2Mg3Al particles at the interface zone. With a thickness of 190µm's Ni coating, part of the Ni coating remained and the interface layer was composed of the Mg-Mg2Ni eutectic structures+ Ni2Mg3Al particles, Mg2Ni layer, Ni solid solution (SS) layer, Al3Ni2 layer, Al3Ni layer and sporadic Al3Ni+Al-Al3Ni eutectic structures from AZ91D side to A356 side in sequence. The interface layer consisting of the Mg-Ni and Al-Ni IMCs obtained with the Ni coating had an obvious lower hardness than the Al-Mg IMCs. The shear strength of the AZ91D/A356 bimetal with a Ni coating of 45 µm thickness enhanced 41.4% in comparison with that of the bimetal without Ni coating, and the fracture of the bimetal with 45µm's Ni coating occurred between the Mg matrix and the interface layer with a mixture of brittle fracture and ductile fracture.

Hypereutectic Al-Si-Cu coatings were prepared by supersonic atmospheric plasma spraying to enhance the surface performance of lightweight alloys. To find out optimum process conditions and achieve desirable coatings, this work focuses on the influence of three important parameters (in-flight particle temperature, impact velocity, and substrate temperature) on the collected splats morphology, coatings microstructure and microhardness. Results show that appropriate combinations of temperature and velocity of in-flight particles cannot only completely melt hypereutectic Al-Si-Cu particles, especially the primary Si phase, but also provide the particles with sufficient kinetic energy. Thus, the optimized coating consists of 98.6 % of fully-melted region with nanosized coupled eutectic and 0.9 % of porosity. Increasing the substrate deposition temperature promotes the transition from inhomogeneous banded microstructure to homogeneous equiaxed microstructure with a lower porosity level. The observations are further interpreted by a newly developed phase-change heat transfer model on quantitatively revealing the solidification and remelting behaviors of several splats deposited on substrate. Besides, phase evolutions including the formation of supersaturated α-Al matrix solid solution, growth of Si and Al2Cu phases at different process conditions are elaborated. An ideal microstructure (low fractions of unmelted/partially-melted regions and defects) together with solid solution, grain refinement, and second phase strengthening effects contributes to the enhanced microhardness of coating. This integrated study not only provides a framework for optimizing Al-Si based coatings via thermal spraying but also gives valuable insights into the formation mechanisms of this class of coating materials.

In order to improve mechanical properties of 6082 aluminum alloy, the SiCp/Al 6082 composites were prepared by the addition of the micron-sized SiC particles combined with the squeeze casting. The effects of the SiCp content and squeeze casting on the microstructure and mechanical properties of the 6082 aluminum alloy were investigated by SEM, EDS, TEM, tensile testing and hardness testing analysis methods. Research results exhibited that the SiCp content and squeeze casting had a significant impact on the microstructure and mechanical properties of the 6082 aluminum alloy. The addition of the SiCp refined the grain size of the 6082 aluminum alloy while caused the increase of the porosity with increasing the SiCp content, especially in the permanent mold casting condition. Compared to the permanent mold casting, the squeeze casting obviously reduced pore defects, refined grain size and made the SiCp distribute evenly as well as bond tightly with the Al matrix. The tensile strength, yield strength, elongation, elastic modulus and hardness of the 6082 aluminum alloy obtained with the SiCp and squeeze casting were remarkably improved, and the optimal mechanical properties were obtained with a 2 wt.% SiCp, and they increased 10.73 %, 72.7 %, 193.9 %, 23.5 % and 25.2 %, respectively, compared to those of the 6082 aluminum alloy obtained without SiCp and squeeze casting. The fracture surface of the SiCp/Al 6082 composites obtained with the squeeze casting was dense and exhibited a ductile fracture mode.

Donor-acceptor co-doped rutile TiO2 ceramics with colossal permittivity (CP) have been extensively investigated in recent years due to their potential applications in modern microelectronics. In addition to CP and low dielectric loss, voltage stability is an essential property for CP materials utilized in high-power and high-energy density storage devices. Unfortunately, the voltage stability of CP materials based on co-doped TiO2 does not catch enough attention. Here, we propose a strategy to enhance the voltage stability of co-doped TiO2, where different ionic defect clusters are formed by two acceptor ions with different radii to localize free carriers and result in high performance CP materials. The (Ta + Al + La) co-doped TiO2 ceramic with suitable La/Al ratio exhibits colossal permittivity with excellent temperature stability as well as outstanding dc bias stability. The density functional theory analysis suggests that L a 3 + A l 3 + V O • • T i 3 + defect clusters and Ta5+-Al3+ pairs are responsible for the excellent dielectric properties in (Ta + Al + La) co-doped TiO2. The results and mechanisms presented in this work open up a feasible route to design high performance CP materials via defect engineering.

Catalysts of Ni supported on home-made mesoporous alumina (Ni/M-Al2O3) were prepared via facile incipient impregnation method and calcined under different temperature (500–800 °C). Compared with catalysts of Ni supported on commercial alumina, they showed much higher conversion and lower carbon deposition in methane dry reforming (DRM). Among the catalysts, Ni/M-Al2O3-700 exhibited the highest DRM activity, with 77.6% CH4 conversion and 85.4% CO2 conversion at 700 °C. TPR revealed that almost all the Ni was in the form of NiAl2O4 spinel after calcination at 700 °C. Due to the strong metal-support interaction of NiAl2O4 structure, the Ni crystal size of Ni/M-Al2O3-700 after reduction was around 5 nm. TGA and TEM results showed its carbon deposition after 20 h DRM test was only 3.8% and mainly in the form of amorphous carbon. This work indicates that the formation of NiAl2O4 spinel is beneficial to activity and stability towards DRM reaction and controlling calcination temperature is crucial.

The unavoidable increase in train speed and load, as well as the aging of railway facilities, is requiring more and more attention to rail defects detection. As a promising tool for rail, in-service high-speed inspection, guided wave–based detection technologies have been developed in succession by researches in the past two decades. However, there is a lack of a systematic review on the developments and performances of these technologies. This article reviews ultrasonic rail inspection methods comprehensively with the focus on the state-of-the-art technologies based on guided wave. Different excitation options, including train wheel, electromagnetic acoustic transducer, pulsed laser, air-coupled, and contact piezoelectric transducer, are described, respectively, along with their inspection sensitivities, regions, and potential speeds. Finally, future challenges and prospects are discussed to a certain extent to provide references for researchers in this area.

Stable barium isotopes are a potential proxy for riverine inputs into the ocean that reflect monsoon variability and climate change. However, dissolved Ba isotope (δ138BaDBa) geochemistry in river estuaries, a dynamic land to ocean transition zone, has rarely been systematically examined to date. Here, we show that significant Ba isotope fractionation occurs at near-zero salinities in the Yangtze and Pearl River Estuary, whereas conservative mixing dominates δ138BaDBa distributions beyond low salinities, which are well predicted by an ion exchange model. Elevated δ138BaDBa in the river endmember results from preferential removal of light Ba isotopes by adsorption to fluvial particles. Subsequently, δ138BaDBa rapidly drops to minimum signatures at increased salinities indicating particle desorption of isotopically light Ba. Nevertheless, the apparently conservative δ138BaDBa-salinity relationship beyond the low-salinity minimum in both estuaries provides a modern calibration for using Ba isotopes as a proxy for paleosalinity and river water inputs into the ocean.

This work was supported by the UK Natural Environment Research Council (award NE/I022973/1) to AAF and NA. Coral skeletal Sr/Ca has valuable potential as a proxy of sea surface temperatures (SSTs). However seawater pCO2 can influence skeletal Sr incorporation and Sr/Ca-SST calibrations derived from present day corals may not be applicable to ancient specimens or older sections of modern corals deposited under lower seawater pCO2 than the present day. In this study we analysed skeletal Sr/Ca in multiple genotypes of massive Porites spp. cultured over a range of seawater pCO2 (from 180 to 750 μatm) and temperature (25°C and 28°C). Multiple linear regression analysis indicates that the Sr/Ca aragonite partition coefficient, KD Sr/Ca is inversely related to seawater temperature and positively related to seawater pCO2 (equivalent to changes in skeletal Sr/Ca of 0.046 mmol mol-1 °C-1 and 0.0002 mmol mol–1 µatm-1 respectively). Applying present day Sr/Ca-SST equations to older coral skeletons growing at lower pCO2 could underestimate seawater temperatures. However KD Sr/Ca vary significantly between some coral genotypes cultured at the same seawater pCO2 indicating that other unidentified processes also influence skeletal Sr/Ca and it is unknown how these processes varied when ancient corals were deposited. We do not observe a significant relationship between KD Sr/Ca and coral calcification rate after combining all coral genotypes to allow identification of the correct KD Sr/Ca to apply to coral records. Postprint

International audience; Check dams have been used throughout the world for a variety of purposes including torrent control, water supply enhancement, agricultural land development, and watershed restoration. National, regional and local governments have invested, and continue to invest, in basin scale erosion-control projects that may include both maintenance of existing and construction of new check dams. The functions of these structures are diverse and vary depending on the geomorphic context where the structures are built. However, although the number of check dams constructed to control floods, regulate sediment transport, reduce upstream reach slopes and sta-bilize torrent beds continues to increase, some projects have experienced disappointing results, and thus project objectives are not achieved. Causes of failure include poor construction quality, inadequate check dam location and lack of adequate design criteria. These failures lead to reduced confidence in using check dams as restoration tools. Moreover, both construction of dense networks of check dams and construction of a few large open structures require major economic investments, however a comprehensive evaluation of their long-term effec-tiveness is still lacking. This review aims to achieve a detailed synthesis of the effects of check dams based on a review of the literature that includes conceptual thinking, field observations and numerical approaches. Using the knowledge gaps identified in this work as a starting point, the review is an effort to join and share scientific and technical information from a variety of sites throughout the world based on the legacy effects of check dams. The role of complex interactions between ecological impacts, geomorphic processes and engineering activities is also highlighted. Overall, this review identifies the self-similar character of check dams and the process feedback loops they initiate across a range of spatial scales and geographic settings.

Platinum (Pt) is practical available candidate for satisfying the requirements of anode catalysts in the proton exchange membrane fuel cells (PEMFCs). Totally dispersed Pt is an ideal way to minimize Pt use, and the develop of Pt-single-atom based hydrogen oxidation reaction (HOR) catalysts should be carried out in a multi-component/-function model system with a clear active site (Pt-single-atom) geometric structure. This work combines the well-defined Na6[H2PtW6O24] clusters and multi-function carbon dots (CDs) to show the highly efficient Pt-single-atom catalyst design for HOR in acid. The mass activity and exchange current density of POMs/CDs (2.18 wt% Pt) achieved 86.72 A mgpt−1 and 3.78 A mgpt−1, respectively, which were 9.5 and 14 times that of 20% Pt/C. Also, this catalyst exhibits better performance than 20% Pt/C in the test of single cell, including higher open circuit potential (OCP), higher power density and better long-time stability. In particular, CDs can effectively improve the catalytic performance of POMs by enhancing the electron acquisition ability of Pt in POMs, the conductivity of composites, the structure stability, the ability to resist toxicity and accelerating the transfer of H+ produced on POMs.

Catalytic conversion of methane to commodity chemicals is highly desired. With methods of density functional theory (DFT) computations, we investigated methane conversion to methanol (MCM) with H2O2 as oxidant over Zn dimer supported by amino nitrogen and pyridinic nitrogen co-doped porous graphene (Zn2@NPG). The facile oxidation of Zn dimer gives rise to the formation of reactive site toward methane activation. The CH3-H bond cleavage with 0.24 eV energy barrier is directly followed by the formation of methanol and regeneration of Zn2@NPG. Further analysis revealed that Zn dimer is strongly stabilized and positive charged by sharing 4 s electrons with N atoms, which ensures high-stability and good electronic conductivity of the Zn2@NPG. Amino N atom exhibits efficient electronic transfer with Zn dimer by forming two Zn-N bonds, endowing its function as an electron reservoir. Amino N as an electron donator promotes oxidation of Zn dimer and as an electron acceptor facilitates deoxidation of Zn dimer and methane conversion. The combined effect of Zn dimer and amino N atoms endows Zn2@NPG with excellent electronic structure for high activity in catalyzing MCM. This work opens a new door to accomplish low-temperature methane conversion on bi-atom catalysts (BACs).

We have experimentally demonstrated both 1.82 μm and 1.84 μm Tm:YAP lasers at the operation mode of continuous-wave (CW) and mode-locking. These individual wavelength lasers are realized by using well-chosen output couplers. For the CW operation, a short Fabry-Perot cavity is employed. The maximum output power of the 1825 nm Tm:YAP laser is 7.04 W, and the corresponding slope efficiency is 59.3%. For 1844 nm Tm:YAP laser, the output power is 7.1 W. A commercial semiconductor saturable absorber mirror (SESAM) is used for realizing continuous-wave mode-locking (CWML) operation. The average output power of Tm:YAP laser at 1823.7 nm is 0.3 W, and the pulse duration is 126 ps. Further, stable CWML laser operating at 1844 nm is realized by inserting a 5 mm fused-quartz plate into the cavity with the Brewster angle. The average output power of 0.63 W is achieved, and the pulse duration is 156 ps.

Identifying whether and when the southern continental margin of the South China Sea (SCS) was part of the South China Block (SCB) is important for Mesozoic–Cenozoic paleogeographic reconstructions of Southeast Asia. In this paper, we present geochronological and geochemical data for dacites from Well NK-1 in the Nansha Block (Dangerous Grounds) of the southern SCS margin to investigate their petrogenesis and tectonic affinity. Zircon U Pb and 40Ar/39Ar datings show that these dacites formed during the Late Triassic (218–217 Ma). The dacites have high total alkali (K2O + Na2O = 7.39–8.42 wt%) and relatively low CaO contents (1.87–3.38 wt%), and show geochemical affinities with A-type granites, with high Zr saturation temperatures (806–855 °C), FeOTot/MgO ratios (5.22–7.48), Zr + Nb + Ce + Y contents (530–680 ppm) and 10,000 × Ga/Al values (2.40–2.94), and relatively low A/CNK values (0.86–1.04). The primitive magma for the dacites was likely generated by partial melting of ancient crustal materials. Late Triassic dacites in the Nansha Block and Triassic A-type granites in the SCB formed in an extensional setting at the continental margin of the SCB. This setting was probably related to the Paleo-Pacific plate subduction that restarted prior to the Early Triassic. Therefore, the southern SCS margin was part of the SCB continental margin during the early Mesozoic, which provides more detailed insights into the paleogeography of SE Asia since the Mesozoic.

The simplified lattice Boltzmann method (SLBM) is relatively new in the LBM community, which lowers the cost in virtual memories significantly and has better numerical stability compared with the single-relaxation-time (SRT) LBM. Recently, SLBM has been extended to simulate thermal flows based on the simplified thermal energy distribution function model. However, the existing thermal models developed for SLBM are not strict in theory. In this work, a coupled simplified lattice Boltzmann method (CSLBM) for thermal flows and its boundary treatment are proposed, where the Navier-Stokes equations for the hydrodynamic field and the convection-diffusion equation for the temperature field are solved independently by two sets of SLBM equations. The consistent forcing scheme is adopted to couple the contribution of the temperature field to the hydrodynamic field. The boundary treatment for temperature field proposed in this work offers an analytical interpretation of the no-slip boundary condition. To validate the accuracy, efficiency, and stability of the present CSLBM, several canonical test cases, including the porous plate problem, the Rayleigh-Benard convection, and the natural convection in a square cavity are conducted. The numerical results agree well with the analytical solutions or numerical results in the literatures, which shows the present algorithm is of second-order accuracy in space and demonstrates the robustness of CSLBM in practical simulations.

Most research about vibro-acoustic optimization focuses on the reduction of the global acoustic response in mid- and even high-frequency ranges. The noise control in concerned local domains inside the acoustic cavity also deserves to be studied. This article deals with a local acoustic optimization in the framework of statistical modal energy distribution analysis (SmEdA) aiming at reducing the noise in concerned local domains of mid-frequency vibro-acoustic systems. As a recently proposed method, SmEdA processes modal energies of the coupled subsystems rather than the subsystem energies directly and permits extending analytical frequency to mid-frequency range. Using a post-processing technique, the local information involving the distributions of kinetic and potential energies inside the acoustic cavity can be estimated. In the optimization model, the acoustic energy in concerned local domains of the cavity is taken as the objective function, considering the constraint on structural weight. By optimizing the thickness distribution of the structural subsystem, the local acoustic response is significantly reduced. The effectiveness of the optimization procedure and the corresponding local acoustic sensitivity technique are illustrated by the given numerical examples. Optimization results indicate: (a) the developed optimization procedure is more effective in reducing the local acoustic response compared with the global acoustic optimization; (b) the modal energies including the kinetic and potential energies in the local acoustic domain tend to be uniformly distributed after optimization.

Microbial induced carbonate precipitation has been widely used in the biomineralization of heavy metals Cd2+. However, the low Cd-tolerance of ureolytic bacteria limits the applications with only low Cd2+concentrations. In this study, we discovered a simple approach to significantly enhance the Cd2+ resistance of ureolytic bacteria through an immediate supplement of Ca2+. The Ca2+ protected the cells by reducing the extracellular and intracellular Cd2+ concentration by about 50%. As a result, the Cd2+ removal efficiency was notably improved by about 100% (52.72% to 99.43%, Cd = 5 mM) with Ca2+ supplement. Moreover, extremely high concentration of Cd2+ could be almost completely removed (99.46% at C0 = 20 mM and 99.60% at C0 = 50 mM) within 24 h. Microstructure analyses indicated that the mineralized precipitates were rhombohedral-shaped CdCO3, CaCO3, and (Ca0.67, Cd0.33)CO3. Furthermore, Ca2+ could also protect ureolytic bacteria against toxicity from other heavy metals.

Recreational fishery (RF) integrates the primary, secondary, and tertiary industries, which has been playing an irreplaceable role in protecting fishery ecological system, conserving fishing resources and creating employment opportunities for local fishery farmers in China. Unfortunately, due to the lack of economic value information, makes current RF management strategies problematic, especially in terms of resource allocation and prioritization of management tasks. To fill such a gap, we employ the tourist satisfaction approach (TSA) to estimate the value of RF resources. In particular, IV-OProbit is used to solve the endogenous issue of the impact of travel costs on travel satisfaction. The results show that travel cost has a significant negative effect on tourist satisfaction. Other attributes, such as the number of RF activities, size of fishing area, water clarity, vegetation coverage, as well as the number of fishing spots all have significant positive effects on tourist satisfaction, and their average MWTP is ¥372.21 ($56.24), ¥123.04 ($18.59), ¥67.47 ($10.19), ¥47.19 ($7.13), and ¥10.14 ($1.53), respectively. Besides, we also find that non-local female tourists with higher income and younger age seem to have higher WTP to improve attributes quality compared to local male tourists with lower income and older age. Furthermore, the local and non-local tourists also show divergent preferences where the locals prefer a large fishing area, while the non-locals prioritize their preference on the diversity of leisure activities. Accordingly, we put forward the general measures and specific measures to protect and enhance the development of recreational fishery.

The silica dispersion and interfacial interactions are two essential factors for preparing silica/rubber composites with excellent dynamic performances. In this work, the thiol−ene click reactions between triethoxysilane-terminated liquid polybutadiene (TTPB) and 3-mercaptopropyl-ethoxy-bis(tridecyl-pentaethoxy-siloxane) (Si747) were applied to adjust silica/natural rubber (NR) interfacial interactions, and the silica dispersion and properties of the resulting rubber composites were also investigated. The results of transmission electron microscopy (TEM), dynamic mechanical analyzer (DMA) and rubber process analyzer (RPA) demonstrated that TS2-NR composite with the mole ratio 2 of Si747 to TTPB exhibited the best silica dispersion and the lowest Payne effect due to the synergistic effects of TTPB and Si747; Solid NMR revealed that the interfacial interaction is the strongest for TS2-NR. Thus, TS2-NR exhibited excellent static and dynamic properties.