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The capsule-type plate heat exchanger (PHE) is a new type of equipment with great potential, which is characterized by the concave and convex capsule-like surface. In this article, new structures consisting of capsules and spherical dimples of PHE were proposed. Flow through a periodic unit cell with four different geometries is simulated numerically to characterize the pressure drop, heat transfer coefficients, and entropy generation rate. The numerical results show good consistency with the existing experimental data. Results show that the flow in capsule-type plate can be divided into recirculation zone and high-velocity zone. The staggered capsule structure and the spherical dimple shape generate more secondary and impinging flows, which provide higher Nusselt number and friction factor. The maximum Nusselt number area changed from the upwind region of capsule to the vicinity of dimple region because of the downwash effect and the fluid impact effect. The Nusselt number is enhanced by 19%–46%, and the friction factor is 1.21–2.9 times to that of the primary capsule-type plate. In addition, Entropy analysis illustrates that the maximum reduction in the dimensionless entropy generation rate is 43.6%. [ABSTRACT FROM AUTHOR]

Among renewable energy sources, wind energy is regarded as one of the fastest-growing segments, which plays a key role in enhancing environmental quality. Wind turbines are generally located in remote and harsh environments. Bearings are a crucial component in wind turbines, and their failure is one of the most frequent reasons for system breakdown. Wind turbine bearing faults are usually very localized during their early stages which is precisely when they need to be detected. Hence, the early diagnosis of bearing faults holds paramount practical significance. In order to solve the problem of weak pulses being masked by noise in early failure signals of rolling element bearings, a novel fault diagnosis method is proposed based on the combination of complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and an improved TFR demodulation method. Initially, the decomposition of vibration signals using CEEMDAN is carried out to obtain several intrinsic mode functions (IMFs). Subsequently, a novel KC indicator that combines kurtosis and the correlation function is designed to select the effective components for signal reconstruction. Finally, an innovative approach based on the continuous wavelet transform (CWT) for multi-scale demodulation analysis in the domain of time–frequency representation (TFR) is also introduced to extract the envelope spectrum. Further fault diagnosis can be achieved by the identification of the fault characteristic frequency (FCF). This study focuses on the theoretical exploration of bearing faults diagnosis algorithms, employing modeling and simulation techniques. The effectiveness and feasibility of the proposed method are validated through the analysis of simulated signals and experimental signals provided by the Center for Intelligent Maintenance Systems (IMS) of the University of Cincinnati and the Case Western Reserve University (CWRU) Bearing Data Center. The method demonstrates the capability to identify various types of bearing faults, including outer race and inner race faults, with a high degree of computational efficiency. Comparative analysis indicates a significant enhancement in fault diagnostic performance when compared to existing methods. This research contributes to the advancement of effective bearing fault diagnosis methodologies for wind turbines, thereby ensuring their reliable operation. [ABSTRACT FROM AUTHOR]

AbstractThe concept of both hierarchy and gradient are incorporated into thin-walled hexagonal tubes for a configuration with optimum crashworthiness and energy absorption. Graded hierarchical hexagonal (GHH) tubes are developed by replacing the corners of an original hexagonal tube with a series of micro hexagonal cells. The total net cross-sectional area as well as the mass are kept the same for all the GHH tubes. The axial crushing behavior of the GHH tubes is investigated in terms of deformation modes, crushing forces and energy absorption. Theoretical solutions are also derived to predict the mean crushing forces (MCFs) of the GHH tubes. Two deformation modes have been identified, a locally layer-by-layer folding deformation (Mode-L) and a globally buckling-like deformation (Mode-G). The hierarchical and graded parameters have significant but quite different influences on the crushing behavior of GHH tubes. The MCF and the specific energy absorption (SEA) can be significantly improved with reasonably hierarchical and graded arrangements, while the initial peak force (PF) remains almost constant. [ABSTRACT FROM AUTHOR]

Hybrid high voltage direct current systems utilized for bulk-power transmission have recently attracted more attention. The overhead lines (OHLs) are mainly used for the implementation of such systems due to their outstanding economic advantages. However, OHLs are vulnerable to temporary faults, jeopardizing the safe and reliable operation of the network. The resiliency to the line faults is of considerable significance to the power transmission. This paper proposes a fault property identification strategy based on the Pearson correlation coefficient for the LCC-MMC hybrid HVDC system which can differentiate temporary and permanent faults. To achieve this, a voltage signal is injected into the faulty line by decreasing the firing angles of the LCC-based rectifier. Based on the established OHLs model and the injected signal, an estimated backward travelling wave can be accurately calculated. The fault property is identified by comparing the wave difference of the real backward travelling wave and the estimated backward travelling wave. The proposed strategy has a high accuracy since all influencing factors including the fault resistance, fault distance, and line parameters have been taken into account. Finally, to verify the efficacy of the proposed algorithm, several simulations have been performed using PSCAD/EMTDC. The simulation results show that the proposed algorithm can effectively distinguish the fault property. [ABSTRACT FROM AUTHOR]

Continuous Si 3 N 4 fiber reinforced SiNO matrix composites (Si 3 N 4 f /SiNO composites) were innovatively prepared for long-time high-temperature resistant wave-transparent materials of hypersonic aircraft. The microstructure, high-temperature mechanical and dielectric properties of Si 3 N 4 f /SiNO composites were investigated in detail. The as-fabricated Si 3 N 4 f /SiNO composites have homogeneous SiNO matrix distribution for the special winding process, which is beneficial for the mechanical strength and wave-transparent properties. The average tensile strength and flexural strength at room temperature is 87.8 MPa and 171.2 MPa respectively, which suggests Si 3 N 4 f /SiNO composites have excellent mechanical strength. The tensile strength value decreases to 54.6 MPa after heat-treated at 1000 ℃ for the surface reactions between the SiNO matrix and Si 3 N 4 fibers. After heat-treated at 1550 ℃, the composites have the tensile strength value of 24.2 MPa for the high strength retention rate of Si 3 N 4 fibers at this temperature. Si 3 N 4 f /SiNO composites have excellent room temperature dielectric properties and excellent dielectric stability in different frequency bands (7–18 GHz). The dielectric constant values vary from 3.69 to 3.75 while the dielectric loss attains the order of 10−3. The dielectric constants and dielectric loss of Si 3 N 4 f /SiNO composites are relatively stable from RT to 800 ℃. The as-fabricated Si 3 N 4 f /SiNO composites that have excellent high temperature resistance and dielectric properties are the ideal high temperature wave-transparent composites. [ABSTRACT FROM AUTHOR]

A tip winglet can reduce the induced drag and the load fluctuation of a blade, considerably improving the hydrodynamic performance of a tidal turbine. Up to now, there are fewer studies on the unsteady effects of winglets, which limits the application of this design scheme. In this paper, a tidal turbine model is established based on computational fluid dynamics (CFD) and verified by a flume experiment. Then, unsteady effects on the turbine blade are analyzed considering different winglet lengths and cant angles. According to the study, the blade performance is optimal when the winglet cant angle is 45°, with about 11% efficiency improvement and about 8% increase in axial force; as the winglet length increases, the performance tends to further improve. In addition, this study demonstrates that the reason why a winglet can reduce blade load fluctuations is that the winglet takes the tip vortex generation position away from the blade rotation plane, instead of reducing the tip vortex intensity. [ABSTRACT FROM AUTHOR]

In this paper, an exploratory data analysis method is employed to investigate the impact of different system parameter combinations on the magnitude and stability of power of flow-induced vibration (FIV). Firstly, orthogonal experimental design within exploratory data analysis is used to set up numerical simulations of flow-induced vibration and collect data on FIV power generation characteristics. Then range method is used to select the optimal parameters combination for flow-induced vibration power generation, and the degree of influence of different system parameters on power and stability is quantitatively described by variance and entropy weight methods. Our results reveal that the optimal parameter combination for power corresponds to m* = 1.343, K = 1200 and ζ = 0.08, and the optimal parameter combination for stability is m* = 1.343, K = 1200 and ζ = 0.04. Additionally, the weight relationship of each system parameter affecting power and stability is W K > W ζ > W m* and W ζ > W m* > W K , respectively. These weight relationships allow for the effective adjustment of the parameter levels to quickly achieve the goal of optimizing power and stability. A new parameter P value-stability is proposed to comprehensively evaluate power magnitude and power stability, and optimal parameter combinations in different vibration branches is achieved. This paper provides new ideas and guidance for the design of the FIV energy harvesting device. [ABSTRACT FROM AUTHOR]

End-stop problem is a critical issue in the hydraulic power take-off (PTO) system. This paper focuses on studying the conversion mechanism of the hydraulic PTO system of the proposed multi-body articulated wave energy converter (WEC), which aims to address the end-stop problem. Taking into consideration the working requirements of the proposed WEC as the constraint condition, the single compound hinge type swing cylinder 6-bar mechanism is designed as WEC's hydraulic PTO conversion mechanism. The movement and dynamics of the mechanism is analyzed, and its parameter optimization mathematical model is established. By integrating software ADAMS and MATLAB with iSIGHT, the optimal design of the mechanism is realized by using a pointer automatic optimizer. The results show that the hydraulic cylinder can avoid the end-stop problem in extreme conditions. Furthermore, it can also make full use of its effective stroke to improve the energy conversion efficiency. Finally, the operational performance of the hydraulic PTO system is validated by sea trials. • Proposed an optimization design method to solve the end-stop problem in hydraulic PTO system. • The type synthesis of the 6-bar mechanism is carried out according to the generalization principle. • An optimized mathematical model of the swing cylinder 6-bar mechanism is established. • The correctness of the optimization results was verified through experiments. [ABSTRACT FROM AUTHOR]

Two-dimensional numerical simulations of flow-induced vibration (FIV) of a square cylinder in laminar flow with a Reynolds number Re = 170 are carried out, and the influence of the mass ratio on the FIV characteristics is studied. The results show that the mass ratio affects the vibration responses distinctly in different regimes. In the vortex-induced vibration (VIV) regime, a larger mass ratio results in a smaller amplitude. On the contrary, in the galloping regime, a larger mass ratio leads to a greater amplitude, causing the galloping starts at a lower reduced velocity. Furthermore, the VIV-galloping coupling effect, as observed in the galloping regime, becomes stronger with increasing mass ratio. To further elucidate the vibration mechanisms, the instantaneous phase lag between displacement and lift force, the work done by the vortex lift and the potential lift, and their influences on vibration responses are carefully investigated. In the VIV regime, the vortex lift contributes primarily to the vibration while the potential lift becomes significant in the galloping regime. More specifically, both forces do positive work in the initial and upper branches of VIV, leading to an increase in the vibration amplitude. However, in the lower branch, the potential lift continues to contribute positively, while the vortex lift does negative work, extracting energy from the vibration system. The counteracting vortex and potential lift cause a decrease in the vibration amplitude. With further increasing the reduced velocity, the vortex lift alternately promotes or inhibits the vibration in the galloping regime, while the potential lift consistently contributes positively to the work done, playing a leading role. As a result, the vibration amplitude increases in the galloping regime. • In VIV, a higher mass ratio corresponds to a smaller amplitude. • In galloping, a higher mass ratio leads to more pronounced vibration. • Different to the vortex-force dominated VIV, galloping is primarily affected by the potential force. [ABSTRACT FROM AUTHOR]

Voltage source converter‐based high voltage direct current (VSC‐HVDC) transmission system has become the mainstream of power construction and plays an increasingly important role in the power system. However, the DC line fault results in shutting down of the converters, which can greatly endanger the security of the power grid. So it is essential to find a fast fault identification strategy for DC line protection technology. In addition, the existing backup protection scheme has the problems of long delay and strict communication synchronisation requirements. Therefore, this study proposes a novel protection scheme for VSC‐HVDC transmission lines based on the fault current integral autocorrelation coefficient. The fault current and fault current frequency characteristics of VSC‐HVDC transmission lines are analysed first. Second, this study proposes a method to filter out distributed capacitance current by current integration and eliminate the oscillation of fault current. Finally, the difference of the current integral during different faults (internal or external fault) is analysed, and the autocorrelation coefficient is introduced to express the difference. Hence, this study proposes a new principle for identifying faults using the autocorrelation coefficient of the fault current integral. Simulation results show that the protection principle is not affected by the distributed capacitive current and does not require strict communication synchronisation. It has an excellent performance in intolerance to fault resistance and noise interference and can be used as backup protection for VSC‐HVDC transmission system. [ABSTRACT FROM AUTHOR]

To reduce carbon emissions and optimize energy utilization of integrated energy system (IES), an integrated electricity-heat-gas energy system containing coupled operation of oxy-fuel combustion capture and power to gas (OCC–P2G) and hydrogen-doped gas equipment is established in this paper. Firstly, the introduction of OCC technology transforms the thermal power unit into the OCC unit. The net output model of OCC unit and the equation of electric-carbon characteristic are established. Secondly, the two-stage refinement model of power to gas (P2G) and the model of hydrogen-doped gas equipment are constructed. Thirdly, considering the fairness principle of punishing positive carbon emissions and rewarding negative carbon emissions, a reward-penalty staircase carbon trading mechanism was constructed to constrain system carbon emissions. On this basis, an economic dispatch model of integrated energy system is established. The simulation results demonstrate that the ratio of wind abandonment is 0%, the actual carbon emission is only 35.08% of carbon quota, and the operation cost is only 237.1 thousand dollars. By setting multiple scenarios for comparative verification, the proposed strategy has lower economic cost and carbon emission. • The electric-carbon characteristic equation and net output power model of OCC unit are established. In addition, the electric-carbon characteristic of OCC unit is analyzed. • The coupled operation of OCC-P2G mode is proposed. The P2G process supplies high-purity oxygen for the OCC unit to broaden the oxygen source. The OCC unit provides the reaction feedstock for P2G device. • Considering the hydrogen-doped operation mode of gas turbine and gas boiler, the conversion efficiency hydrogen energy is improved. In addition, the mathematical model of hydrogen-doped operation of gas equipment is established. • Considering the fairness principle of carbon trading, the reward and punishment ladder-type carbon trading (RPLCT) mechanism is established. On this basis, a low-carbon optimal scheduling model of IES is proposed. [ABSTRACT FROM AUTHOR]

In recent years, the high percentage of wind power accessibility in Northwest China has worsened the dilemma of peak regulation and spinning reserve in the power system, frequently resulting in wind abandonment. Therefore, a concentrated solar power (CSP) plant equipped with an electric heater (EH) is implemented to join the peak regulation, and the joint peak regulation strategy between thermal power units (TPUs) and a CSP plant is proposed. Firstly, the peak regulation principle of a CSP plant with EH is analyzed in detail. The CSP plant is divided into load mode and power source mode of peak regulation, and mathematical models of the two modes are established. Secondly, the effectiveness of joint peak regulation of TPUs and CSP plants with EH is analyzed, and the principle of low-carbon power supply during peak and off-peak periods is analyzed in the proposed strategy. On this basis, the ladder carbon trading mechanism is introduced to quantify the low-carbon level of the system, and an economic scheduling model considering the operation cost of the system is established to determine the optimal schedule. The results suggest that the proposed scheme can improve the operational efficiency of the system and create more consumptive space for wind power by utilizing the flexible operating potential of a CSP plant. [ABSTRACT FROM AUTHOR]

In this paper, a machine learning method based on Deep Neural Network (DNN) is used to establish a predictive model for flow-induced vibration (FIV) power output, and the power database is constructed based on this model. The results reveal that the power database can quickly and efficiently obtain power values for any parameter combination, significantly improving the efficiency of studying the power response of flow-induced vibration. Its accurate prediction ability, low cost and time consumption have made the database a useful tool. Furthermore, the power database can provide power values for various parameter combinations to comprehensively analyze the impact of system parameter combinations on power. The screening results indicate that the optimal power output for the single oscillator flow-induced vibration energy harvesting is 22.71 W and the optimal power for the dual oscillator FIV energy harvesting is 36.38 W. A power database of single and dual oscillators flow-induced vibration harness energy provides a novel method for the study of flow-induced vibration power generation. • A power database is constructed to retrieve power values for any given combination of parameters. • Training a deep neural network (DNN) model with simulated data that includes added noise enhances the accuracy of predictions. • The optimal value and its corresponding parameter combinations are obtained. [ABSTRACT FROM AUTHOR]

The out-of-plane crushing resistance of fractal-like honeycombs with self-similar hierarchy are investigated numerically and analytically. The hierarchical honeycombs are developed via replacing each three-edge vertex of a regular hexagonal honeycomb by a smaller hexagon. Hierarchical honeycombs with higher orders are constructed by repeating this process. Theoretical solutions are derived based on the Super Folding Element (SFE) theory to predict the mean crushing forces (MCFs) of the hierarchical honeycombs. Numerical simulations are also conducted in conjunction with the theoretical solutions. Crushing resistances of three groups of hierarchical honeycombs with different relative densities are explored subsequently. Good agreement between results obtained using theoretical and numerical methods indicates that the theoretical predictions are reliable. The results show that hierarchy can significantly improve the crushing resistance of honeycombs. It is found that the MCFs of first to fourth order hierarchical honeycombs are improved by 71%, 114%, 201% and 309% compared with the regular honeycomb under the same relative density, respectively. It reveals that the amplification of the MCF from one generation to the next approaches a constant (ξ n  ≈ 1.26) when the hierarchical order is sufficiently large. The potential maximum achievable amplifications of the MCF for hierarchical honeycombs of different relative densities are also discussed. [ABSTRACT FROM AUTHOR]

Photodegradation is a very important elimination pathway of Oxytetracycline (OTC) in aquatic environments. The photochemical behavior of OTC in absence/presence of nitrate, iron (III) and bicarbonate, especially their combinations, was systematically studied in aqueous solution by employing a Suntest-CPS+ sunlight simulator in this work. Meanwhile, the effect of solution pH (4.8–9.1) and irradiation intensity (250–500 W/m 2 ) on the removal efficiency of OTC have also been assessed. The results showed that OTC degradation followed a pseudo-first-order kinetics in most conditions except for irradiation in neutral/alkaline solutions and in presence of NO 3 − , where a two-step pseudo-first-order kinetics was obeyed. OTC degradation was highly pH-dependent and increased significantly with increasing pH. The presence of NO 3 − and HCO 3 − promoted the photochemical loss of OTC in aqueous solution by generating hydroxyl radicals and adjusting solution pH, respectively; whereas iron (III) was found to play a negative role under the conditions studied. The influence of NO 3 − coupled with Fe 3+ was not a simple additive effect and the overall performance was to inhibit OTC degradation. In addition, combination of HCO 3 − and NO 3 − exhibited an antagonistic effect. Results from irradiation in co-presence of NO 3 − , Fe 3+ and HCO 3 − suggested that direct photolysis of OTC was much more efficient than its indirect photolysis. These results provide a meaningful reference for understanding the fate and transformation of OTC in natural water systems. [ABSTRACT FROM AUTHOR]

Flow Induced Vibrations (FIV) of a single, rigid, circular cylinder with one-sided PTC (passive turbulence control) are investigated experimentally and numerically for Reynolds number 30,000 ≤  Re  ≤ 110,000. Comparisons of response are made between symmetric and one-sided PTC-cylinder. For the one-sided configuration, different PTC location angles for the one-sided configuration are applied to initiate the asymmetrical FIV, which is studied in detail. A user-defined function, combined with dynamic-mesh is established in a commercial solver. At different flow speeds in the vortex induced vibration (VIV) and galloping ranges, flow-field details and displacement time-history at selected positions of the cylinder are presented and discussed. Conclusions of the asymmetrical oscillation and the effect of selective roughness are drawn with respect to the flow speed, damping ratios and the PTC locations angle at the end. [ABSTRACT FROM AUTHOR]

Energy demand in China has risen rapidly and reached an unprecedented level due to the high-speed economic growth and modern development. As a result, the Chinese government faces a growing pressure to address the energy shortage and environmental deterioration, mainly resulting from an over-dependence on fossil energy. China has become both the largest energy consumer and CO 2 emitting country in the world in 2015. Utilization of potential for renewable energy is necessary for changing inappropriate energy consumption structure, protecting environment and achieving sustainable economic and social development. In view of such mentioned situation, this paper firstly introduces the energy structure as well as the development status of renewable energy in China, which includes hydropower, wind power, solar power, biomass power and other renewable energy. Besides, based on the current situation in China, the paper makes a preliminary prediction of the development of renewable energy in the country for the future decades, and proposes targeted countermeasures and suggestions. [ABSTRACT FROM AUTHOR]

In order to pursue better crashworthiness and higher energy absorption efficiency, a new type of multi-cell honeycomb (quadri-arc) was designed and followed by a series of numerical studies on in-plane dynamic crushing behavior and energy absorption property under different impact loading. Meanwhile, simulations of a regular circular single-cell honeycomb were also conducted as comparisons. Three distinct deformation modes were identified from the observation of deformation profiles: quasi-static, transition and dynamic, respectively. Simulations indicate that deformation modes are not only influenced by impact velocity but also sensitive to relative density of the honeycomb, based on which a deformation map was summarized. Furthermore, the plateau stress and energy absorption of the quadri-arc honeycomb as well as the circular honeycomb were explored and compared, during which effects of impact velocity and relative density of the honeycomb were discussed in detail. The results show that a much higher plateau stress and better energy absorption efficiency for the quadri-arc honeycomb are predicted compared to the circular honeycomb, especially in the quasi-static case. The investigation suggests that design of the quadri-arc multi-cell will enhance the crashworthiness and energy absorption capacity of honeycombs. [ABSTRACT FROM AUTHOR]

Maneuverability is one of the important tactical and technical indexes of fighter aircraft. In this paper, the finite element method is used to establish a dynamic model of the rotor system that can consider arbitrary maneuvering flight form and rotor speed variation during the flight, and the vibration characteristic of the dynamic model is investigated in detail. In addition, the nonlinear forces caused by bearings and oil film are also considered. The Newmark-β method combined with Newton-Raphson method is adopted to solve the dynamic equations. The influences of speed variation, rolling, pitching, and yawing maneuver loads on the vibration responses of the rotor system are also evaluated. [ABSTRACT FROM AUTHOR]

The marine ranching industry in China is transitioning from traditional farming to a digital and intelligent model. The use of new technologies, algorithms, and models in the era of artificial intelligence (AI) is a key focus to enhance the efficiency, sustainability, and resilience of marine ranch operations, particularly in risk and disaster management. This study proposes a methodology for applying deep reinforcement learning to decision making in this domain. The approach involves creating an environmental model based on decision objects and scenarios, determining the number of decision makers, and selecting a single or multi-agent reinforcement learning algorithm to optimize decision making in response to randomly generated disasters. Three core innovations are presented: the development of a disaster simulator for marine ranching scenarios, the application of reinforcement learning algorithms to address risk and disaster management problems in marine ranching. Future research could focus on further refining the methodology by integrating different data sources and sensors and evaluating the social and economic impacts of AI-driven marine ranching. Overall, this study provides a foundation for further research in this area, which is expected to play an increasingly important role in global food production, environmental sustainability, and energy efficiency. [ABSTRACT FROM AUTHOR]

Indentation response and energy absorption property of honeycomb sandwich panels subjected to drop-weight impact under a spherical impactor were investigated. Experiments were conducted using a pendulum-impact system. A three-dimensional finite element model with micro-structure considered was built and validated. In conjunction with experimental and numerical methods, analytical models of indentation response and energy balance specifically aimed to solve problems of low-velocity impact of a spherical indenter on sandwich panels were deduced. Results show that a hemispherical residual dent caused by bending of top face-sheet and core crushing is left on top face-sheet after impact. It also concludes that more than 80% of impact energy is absorbed mostly by top face-sheet and honeycomb core. The main form of energy dissipation is plastic dissipation. In addition, parametric studies were carried out to explore effects of impact energy on impact behavior by altering impact velocity or impactor mass. Different effects are observed for the two approaches and some useful semi-empirical formulations based on both experimental and numerical results are overfitted to estimate the residual dent depth and energy absorbed during a drop-weight impact event on a honeycomb sandwich panel under a spherical impactor. [ABSTRACT FROM AUTHOR]

Artificial upwelling can lift nutritious deep ocean water to sunlit layer, as a result, it is able to promote primary production and is being paid more and more attention all over the world. Kinds of artificial upwelling method have been invented in recent years, however, few of them can fulfill the requirement of desired flow rate and balanced budget. The design of an air-lift artificial upwelling device powered by hybrid energy system is presented in this paper, where solar, wind and wave energy is exploited together to induce artificial upwelling. The preliminary results of an open sea trial lasted for 7 days have demonstrated that the hybrid system assembled in a floating platform with surface area of 12.5 m 2 can lift 4234 m 3 deep seawater from more than 20 m depth. In particular, the operation based on optimal dispatch strategy showed that the unit cost of induced artificial upwelling is only 0.005 US $/m 3 . The work presented in this paper constitutes a step towards the development of an advanced hybrid energy system used for artificial upwelling. [ABSTRACT FROM AUTHOR]

The mechanical behavior of honeycomb sandwich structures under low-velocity impact is of great significance. An experimental and numerical investigation on surface deformation and energy absorption subjected to low-velocity impact is undertaken. A high-speed camera system is employed to record the acceleration attenuation process of the impactor, a projection profile system is introduced to measure the surface profiles of the panel and the depth of the ultimate indentation is obtained. A three-dimensional finite element model is constructed and validated by the experimental results. Indentation characteristics and energy absorption are analyzed and in good agreement with experimental data. Effect of adhesive layers on energy absorption is discussed and the contribution of the facesheets and the honeycomb core to the energy absorption process is analyzed separately. Results shown that the effect of adhesive layers on energy absorption is non-ignorable and the honeycomb core plays a dominant role in energy absorption. Most of the energy absorbed by the honeycomb sandwich panel is expended as plastic dissipation, and the rest is transformed into strain energy. [ABSTRACT FROM AUTHOR]

In order to deeply study the hydrokinetic energy harnessing of flow induced vibration and provide design basis for industrial application, unsteady RANS method and Spalart-Allmaras turbulence model, combined with dynamic mesh technology, were used to study the vortex induced vibration-galloping coupling separation characteristics. It is found that hard galloping is caused by the separation of VIV-galloping under certain conditions, and is a cognitive deficiency caused by the absence of self-excited galloping branch in the reduced velocity range studied. When the mass ratio increases or the system stiffness decreases to a certain value, the separation of VIV-galloping will occur, which will be aggravated with the increase of mass ratio or the decrease of stiffness. The study also showed that the VIV-galloping coupling phenomenon is essentially controlled by the mass ratio and stiffness of the system. The mass ratio determines the range of upper branch, the smaller the mass ratio, the wider the upper branch. At the same time, the mass ratio and the stiffness determine the natural frequency of the system, and the smaller the natural frequency, the larger the critical reduced velocity of galloping(U c r i * = − 17.12 003 f n , w a t e r + 26.99599). In order to improve the output power of the system, the critical reduced velocity of galloping should not be greater than the maximum reduced velocity of the upper branch, to avoid occurrence of the phenomenon of VIV-galloping coupling separation. • The hard galloping belongs to the VIV-Galloping coupling separation phenomenon. • When the mass ratio increases or the system stiffness decreases to a certain value, the VIV-Galloping coupling separation phenomenon will occur. • The critical reduced velocity of galloping is negatively correlated with the natural frequency of-system(U c r i * = − 17.12 003 f n , w a t e r + 26.99599). • Vortex-Galloping coupling phenomenon is controlled by mass and natural frequency. [ABSTRACT FROM AUTHOR]

• Oscillating-water-column devices are integrated into floating wind turbines. • Time-domain numerical framework for hybrid wind-wave platforms is proposed. • The proposed numerical framework is validated against scale model tests. • Power take-off control influences on power and loads are investigated. Integrating floating offshore wind turbines with oscillating-water-column wave energy converters has been seen as a promising solution for hybrid offshore renewable energy production, as the cost-effective wave energy devices could possibly help increase the overall power absorption, reduce platform dynamic responses, and mitigate loads for critical wind turbine structures etc. As most existing research works on dynamic analysis of these hybrid concepts are based on frequency-domain simulations or scale model experiments, this work focuses on establishing an aero-hydro-elastic-servo-mooring coupled numerical framework for integrated time-domain dynamic analysis. In particular, the water column dynamics are characterised based on an equivalent virtual oscillating body approach so that the time-domain analysis capability for oscillating-water-columns with power take-off control is enabled. For validation, a novel combined concept is designed, and its time-domain numerical results under various environmental conditions have been compared against the 1:50 scale model wave basin test data. Good agreement has been observed between the numerical and experimental results, demonstrating the feasibility of the proposed numerical framework. Furthermore, different power take-off control strategies for the oscillating-water-column wave energy converters have been proposed, and it is found that the designed gain-scheduling control schemes are more beneficial for mitigating the platform motion responses and wind turbine structural loads compared with traditional linear damping control, resulting in 15% platform pitch motion mitigation and 6% tower base fatigue load reduction. Further studies on multi-objective optimal power take-off control design regarding both load reduction and power maximisation could be conducted for hybrid energy platforms based on the established numerical framework. [ABSTRACT FROM AUTHOR]

• The scheme of expressing the fault characteristics of DC systems by elastic coefficients has never appeared in previous papers; • This solution innovatively uses the first traveling wave of the whole process to solve the problem of high-impedance faults in the time domain, which avoids the problems caused by protection in the frequency domain; • Compared with the existing protection scheme, this scheme has stronger anti-interference and fault resistance capabilities; • The scheme is universal and can be applied to all DC systems with boundary elements. Advancing the reform of the energy structure and developing renewable energy has become the current boom. DC transmission technology is an effective means to solve the problems of new energy consumption and long-distance, large-scale power transmission. After the rapid development of DC transmission technology, a situation where multiple types of line-commutated converter (LCC), voltage source converter (VSC), and line-commutated converter-voltage source converter (LCC-VSC) coexist have been formed. The diversification of topological structures leads to insufficient applicability of existing DC protection schemes. In addition, poor resistance to high resistance faults is the main problem of existing traveling wave protection. To improve the applicability and anti-interference ability of the traveling wave protection scheme, a single-ended traveling wave protection scheme based on elastic coefficient is proposed in this paper. First, the time-domain and frequency-domain expressions of the first traveling wave are deduced and the influence of the boundary element transfer function on it is analyzed. Subsequently, the elastic coefficient is introduced and fused to the first traveling wave. Finally, a protection scheme including a starting element, a fault identification element, and a fault pole selection element is proposed. The experimental results of various topologies (LCC, VSC, LCC-VSC) verify the reliability and scalability of the proposed protection scheme. [ABSTRACT FROM AUTHOR]

A numerical investigation was performed to further understand the physical significance of bird striking on a rotary jet-engine fan. A new numerical bird model considering more geometric characteristics than traditional ones was established first, during which the smooth particles hydrodynamic (SPH) method and an equation of state (EOS) were employed. The numerical method and material model were indicated to be reasonable by a validation analysis. Then, a preliminary study of a rigid target struck by a realistic bird from four different orientations including head, tail, bottom and wing sides as well as a traditional hemispherical-ended cylinder model were simulated. It was found that bird geometry and impact orientation had significant effects on impact response and kinetic energy loss of the bird. Furthermore, the same load conditions were conducted on a rotary jet-engine fan and followed by a series of parametric studies, including impact force history, kinetic energy loss of the bird, deformations of the blade tips and von Mises stresses of the blade roots. The results showed that both bird geometry and impact orientation had significant and non-ignorable influence on bird striking on a rotary jet-engine fan and bottom side was the most dangerous case. Considering more geometric characteristics of the bird and impact orientation in studies of bird strike problems was proved to be meaningful and necessary. [ABSTRACT FROM AUTHOR]

Wave energy is being increasingly regarded as a major and promising resource since the artificial upwelling was invented. There are many different ways to convert wave energy to electricity and some other energy such as the power supply for artificial upwelling in this paper. An overview of wave energy converters in artificial upwelling application as well as the power systems and environmental energy conversions for the artificial upwelling all over the world is given in this article. Some basic principles are present, assessment and advices are shown for each category. Some suggestions of the outlook of power systems and wave energy converters in air-lift artificial upwelling application are also given. [ABSTRACT FROM AUTHOR]

This paper presents a new concept of multi-axis wave energy converter (WEC), which can capture wave energy from multiple directions of motion. It describes the modelling of the multi-axis WEC and presents the results of laboratory experiments on the power capture of the multi-axis WEC in a wave tank subjected to synthesized scaled sea waves. The experiments investigate the influence of parameters such as buoy structure, damping and inertia modification (ballasting) on the hydrodynamic performance. The experimental results indicate that the multi-axis WEC yields very good performance under a variety of wave conditions. It is also demonstrated that, by utilizing more than one direction of motion, the multi-axis WEC proves capable of supplying more power than a single-axis WEC. This work constitutes a preliminary step towards the development of an advanced concept of WEC. [ABSTRACT FROM AUTHOR]

The honeycomb sandwich composite material has been widely applied in engineering due to its excellent mechanical performance. The elastic properties of honeycomb core is of crucial importance in efficient mechanical analysis. An approach on determining the equivalent elastic modulus of honeycomb core using experimental modal data is proposed in this paper. Based on analytically predicted elastic constants of the pure core, the initial finite element model of a honeycomb panel is constructed using a three-layer sandwich theory; according to errors that exist in analytically estimated equivalent parameters and the sensitivity analysis of modal frequencies with respect to system parameters, the out-of-plane shear moduli G cxz and G cyz are selected to be determined. Consequently, the two parameters are determined by minimizing an objective function which is formulated with vibration test and numerical modal data. Comparative investigations are conducted to illustrate that the initial values of the parameters with physical significance play an important role in the identification procedure. The presented method can provide accurate and reliable predictions of material constitutive parameters of honeycomb core. [ABSTRACT FROM AUTHOR]

• This paper first puts forward the concept of low-frequency reactive power in DC lines and introduces wavelet transform and Hilbert transforms to calculate low-frequency reactive power. • This paper proposes a scheme of using DC low-frequency reactive power to characterize distributed capacitor current, which solves the problem of disorder of distributed capacitor current. • This paper uses the DC low-frequency reactive power to construct a protection scheme for the first time, which solves the long delay problem of current differential protection in the DC system. • Compared with the existing backup protection principle, the proposed protection principle can rapidly and accurately operate and tolerate the uncertainty caused by up to 500Ω fault resistance, 10 dB noise. Multi-terminal flexible DC power grid has become the mainstream of power construction and plays an increasingly important role in the power system. However, the DC line fault results in the shutting down of the converters, which can greatly endanger the security of the power grid. So it is essential to find a fast fault identification strategy for DC line protection technology. While the existing backup protection has low reliability due to the existence of distributed capacitance current. Therefore, this paper proposes a novel protection scheme using low-frequency transient reactive power. Through analyzing the characters and relationship between the reactive power of the DC line and the low-frequency fault information during a fault., the fault is identified with the difference of low-frequency reactive power. Then a novel algorithm for calculating low-frequency reactive power using Wavelet transform and Hilbert transform is introduced in this paper. Furthermore, the protection scheme is not affected by the distributed capacitor current in the high-frequency band because of the application of the low-frequency fault information. Finally, the effectiveness and superiority of the protection scheme are proved by simulation of the VSC-MTDC power grid. [ABSTRACT FROM AUTHOR]

• This paper proposes a protection scheme based on line attenuation characteristics. • The proposed protection scheme does not rely on boundary elements. • The proposed protection scheme has stronger resistance to fault resistance and noise. The line-commutated converter-voltage source converter (LCC-VSC) three-terminal DC transmission system is one of the effective means for large-scale new energy transmission and consumption, and a fast and reliable protection scheme is the key to its reliable operation. However, the LCC-VSC DC system has characteristics such as LCC converter and VSC converter control strategies, fault response, and uneven boundary elements, which makes it difficult to directly apply the existing protection principles. To the above problems, this paper first proposed a single-ended protection principle based on line attenuation characteristics. The protection principle uses the ratio of the high and low-frequency signals of the line mode voltage to express the line attenuation characteristics and uses this ratio to identify internal and external faults. A model of the LCC-VSC three-terminal transmission system is established to verify the feasibility and effectiveness of the proposed protection scheme. The simulation results show that the proposed protection principle can accurately identify internal faults and external faults and has a strong ability to withstand fault resistance and noise interference. [ABSTRACT FROM AUTHOR]

A 1/64th scale prototype of multi-axis wave energy converter (WEC) has been tested in the wave tank and the overall concept has been verified. It is shown that when multiple directions of motion are involved, the multi-axis WEC proves to be able to supply more power generation than a single axis one. Results demonstrated that the optimal resonant frequency for maximum power output under different damping values does not vary with wave climate. It is also shown that large overload capability of the system is critical, and indicated that, electric power system is essential to reduce power fluctuations. [ABSTRACT FROM AUTHOR]

Highlights: [•] Improved control of individual blade pitch for wind turbines. [•] The controller is based on the proportional-integral-plus (PIP) algorithm. [•] The proposed approach is demonstrated to be more robust to system disturbances than an equivalent PID design. [Copyright &y& Elsevier]

• This paper analyzes the amplitude-frequency characteristics of the measured wave impedance of the LCC-VSC hybrid three-terminal DC transmission system, and constructs the single-ended protection principle based on this. • The proposed protection principle solves the problem of different boundary components in the LCC-VSC hybrid DC system, and the scope of application is larger than that of traditional boundary components. • The feature that the proposed protection principle is not affected by fault resistance solves the problem that the traditional single-ended traveling wave protection principle is difficult to identify remote high-resistance faults. • The proposed protection principle has a stronger ability to withstand fault resistance (800 Ω) and noise (20 dB) than the traditional protection principle. Since the line-commutated converter-voltage source converter (LCC-VSC) hybrid technology combines the advantages of line-commutated converter-based high voltage direct current (LCC-HVDC) and voltage source converter-based high voltage direct current (VSC-HVDC), it has a very good prospect for engineering applications. But, the LCC-VSC HVDC system has characteristics such as LCC converter and VSC converter control strategies, fault response, and uneven boundary elements, which makes it difficult to directly apply the existing protection schemes. To solve the above problems, this paper proposes a single-ended protection scheme based on wave impedance. First, the amplitude-frequency characteristics of the wave impedance of the LCC-VSC three-terminal hybrid DC transmission line are analyzed. Subsequently, a protection scheme is proposed to identify internal faults and external faults by combining the wave impedance amplitude criterion with the current starting criterion. Finally, the model of the LCC-VSC three-terminal transmission system is used for simulation. The simulation results show that the proposed protection scheme has a strong anti-fault capability (800 Ω) and noise interference (20 dB). [ABSTRACT FROM AUTHOR]

This paper presents a constant-pressure hydraulic PTO system that can convert stored pressure energy into electrical energy at a stable speed through hydraulic motors and generators. A multi-chamber cylinder can be connected to the main power generation circuit by check valves, and the motor displacement can be controlled by a fuzzy controller to maintain the main power generation circuit under stable pressure. The hydraulic transformer can control the forces applied to the floater. The hydrodynamic parameters of the floater are calculated by AQWA, and the optimal PTO damping of the hydraulic system is analyzed as the target of transformer control. MATLAB/Simulink and AMESim are used to carry out the co-simulation. Three kinds of wave elevation time-series for the specific state are designed for the simulation. In the co-simulation, three approaches are carried out for the simulation including no control strategy, fuzzy control with a fixed transformer ratio, and fuzzy control with a variable transformer ratio. Under the fuzzy control with a fixed transformer ratio, the floater displacement and captured energy do not increase significantly, but the oil pressure fluctuation is very stable, which indicates that the fuzzy controller maintains the stability of the main power circuit. While under fuzzy control with a variable transformer ratio, the power generation is not larger than those under no control strategy or fuzzy control with a fixed transformer ratio, which proves that this hydraulic transformer concept is less efficient. [ABSTRACT FROM AUTHOR]

Abstract: Cardiomyocyte cell death is a major contributing factor for diabetic cardiomyopathy, and multiple mechanisms have been proposed for its development. We hypothesized that following diabetes, an increased nuclear presence of the Forkhead transcription factor, FoxO1, could turn on cardiac cell death through mediation of nitrosative stress. Streptozotocin (100mg/kg) was used to induce irreversible hyperglycemia in Wistar rats, and heart tissues and blood samples extracted starting from 1 to 4days. Diazoxide (100mg/kg), which produced acute reversible hyperglycemia, were followed for up to 12h. In both animal models of hyperglycemia, attenuation of survival signals was accompanied by increased nuclear FoxO1. This was accompanied by a simultaneous increase in iNOS expression and iNOS induced protein nitrosylation of GAPDH, increased GAPDH binding to Siah1 and facilitated nuclear translocation of the complex. Even though caspase-3 was cleaved during diabetes, its nitrosylation modification affected its ability to inactivate PARP. As a result, there was PARP activation followed by nuclear compartmentalization of AIF, and increased phosphatidyl serine externalization. Our data suggests a role for FoxO1 mediated iNOS induced S-nitrosylation of target proteins like GAPDH and caspase-3 in initiating cardiac cell death following hyperglycemia, and could explain the impact of glycemic control in preventing cardiovascular disease in patients with diabetes. [Copyright &y& Elsevier]

Abstract: Wave energy is being increasingly regarded in China as a major and promising resource. There are many different ways to convert wave energy to electricity and some other energy. Hydraulic systems are used most widely in some of them to realize this conversion. An overview of hydraulic systems in wave energy application as well as the relevant technologies in China is given in this article. Some basic principles are presented, assessment and advices are shown for each category. Some suggestions of the outlook of hydraulic systems in wave energy application are also given. [Copyright &y& Elsevier]

Abstract: The progress in wave energy technologies in China during the past decade is briefly reviewed. And the description is focused on the wave energy resource and the current status of wave energy in China. The difficulties facing wave energy developments in China are summarized. The national policy of wave energy developments is outlined and perspectives of wave energy in China are discussed. [Copyright &y& Elsevier]

The effect of ambient turbulence intensity on the flow induced oscillations of rigid circular cylinders with symmetric and asymmetric local turbulence stimulation is studied. Cylinders oscillate in one degree of freedom transversely to a steady uniform flow. Two-dimensional unsteady Reynolds-Average Navier-Stokes equations with the Spalart-Allmaras turbulence model are used to solve the problem numerically. Three freestream turbulence intensity values (0.2%, 1%, 5%) are used to study the influence of turbulence intensity on vortex pattern. Simulation results are compared with experimental data measured in the Marine Renewable Energy Laboratory of the University of Michigan in the range of 30,000 ≤ Re ≤ 110,000. The amplitude ratio, lift coefficient, vortex modes, and the interactions between vortices and cylinders are observed and discussed. Major conclusions are: (a) Vortex patterns strongly depend on the freestream ambient turbulence intensity. (b) Low turbulence intensity can generate multi-vortex patterns at high Re. (c) High turbulence intensity results in fewer separations of a shed vortex into multiple vortices inducing emergence of elongated vortex patterns. • Low turbulence intensity induces irregular vibration response and multi-vortex patterns. • High turbulence intensity results in regular vibration with simpler vortex patterns. • Asymmetry oscillation of the cylinder becomes less pronounced with increase turbulence intensity. [ABSTRACT FROM AUTHOR]

Overhead lines (OHLs) in High Voltage Direct Current (HVDC) systems are vulnerable to temporary faults. Recovering power transmission by reclosing is of considerable significance to the grid reliability. However, the traditional auto-reclosing strategy will result in a secondary shock to the direct current (DC) system if the fault is permanent. Besides, a long delay is required to ensure that all types of temporary faults are cleared. To address these two challenges, this paper proposes an adaptive reclosing algorithm which can actively identify the fault property and fault disappearance time. Firstly, the discharging process of the fault point is analyzed, and the dominant frequency characteristics of the fault voltage under different fault properties are revealed. Then, the fault property and the fault disappearance time are identified based on the change time of the dominant frequency. Moreover, the influencing factors, including the fault resistance and the dead zone, are also analyzed. Finally, the algorithm is verified under different fault locations, fault resistances, arc lengths, noises, sampling frequencies and dead zone in PSCAD/EMTDC. The results show that the algorithm is effective, and its dead zone is less than 8% of the line. [ABSTRACT FROM AUTHOR]

Abstract: Surface-to-bed heat transfer and pressure measurements were carried out in a 0.17 m ID pulsed bubbling fluidized bed with glass bead and silica sand particles having mean diameters ranging from 37 μm to 700 μm to investigate the effects of flow pulsation on heat transfer and bed hydrodynamics. A solenoid valve was used to supply pulsed air to the bed at 1 to 10 Hz. The bed surface was found to oscillate with the frequency of pulsation, the oscillation''s amplitude decreasing with frequency. The standard deviation of the bed pressure drop in the pulsed bed was found to be larger than that in the conventional bed due to the acceleration force imposed by pulsation. For both Geldart B and A particles, high frequency pulsation (7, 10 Hz) enhances the heat transfer compared to continuous flow, the enhancement diminishing with superficial gas velocity and particle size. For Geldart B particles, the effect of pulsation on heat transfer ceases around U o/U mf =3.5, whereas 24% improvement in heat transfer coefficient was obtained for 60 μm glass bead particles (Group A) at superficial gas velocities as high as U o/U mf =27. Furthermore, in the fixed bed (U o/U mf <1) for Geldart B particles, 1 Hz pulsation was found to be very effective resulting in two- to three-fold increase in heat transfer coefficient compared to continuous flow at the same superficial gas velocity. The flow pulsation loses its effect on heat transfer with increasing static bed height, i.e., when H bed/D >0.85. [Copyright &y& Elsevier]

• Heat transfer performance of a Lightnin stirred reactor coupled with draft tube has been investigated. • The optimized impeller off-bottom clearance has been obtained in the draft tube stirred tank. • The time-correlation variation of heating rate and synergistic angle has been investigated. • A correlation formula coupled by multifactor for enhancing heat transfer in a stirred tank has been proposed. The heat transfer issue in stirred tanks is a prevalent concern in the industry. This article aims to investigate the fluid flow and heat transfer within a stirred tank equipped with a Lightnin A320 impeller coupled with a draft tube (DT) structure. The heat transfer performance of a 37 L jacket stirred tank is experimentally measured with the rotation speeds of 50 ‒ 300 RPM. The effects of off-bottom clearances and rotational speeds on mixing and heat transfer performance are explored using Computational Fluid Dynamics (CFD) by flow patterns, local velocity, turbulent kinetic energy (TKE), helicity, vorticity, heat transfer coefficient, synergy angle, extensional efficiency, and coefficient of variation (CoV) , respectively. The numerically predicted temperature curves have a good agreement with the experimental results. An optimal off-bottom clearance with C/D = 0.43 is found in this stirred tank. Furthermore, empirical correlations are developed to predict heat transfer performance by analyzing the relationship between wall heat transfer coefficient, power consumption, and heat transfer rate. By evaluating the variation of the temperature gradient synergy angle with time and rotational speed of the stirred tank, it was determined that a stabilization time of 120 s is required for the synergy angle. In the area outside the DT, 80 % of the region exhibits extensional efficiency values greater than 0.5. For 100 ‒ 300 RPM, achieving a CoV of 0.01 requires 48.36 %, 67.26 %, 76.81 %, 82.34 %, and 85.67 % less time compared to that of 50 RPM, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

In marine environments, tidal currents exhibit periodic changes in both direction and velocity. Consequently, tidal turbines often operate under yawed conditions. While conventional horizontal-axis turbines show decreased performance and undergo periodic load fluctuations due to blade rotation when yawed, research on the effects of yaw on ducted turbines has been sparse, leaving the underlying impact mechanisms poorly understood. This paper presents a three-dimensional hydrodynamic model of a ducted turbine, developed using the computational fluid dynamics method and validated through flume experiments. The hydrodynamic characteristics of the ducted turbine when operating under yawed conditions are analyzed using large eddy simulation. The findings indicate that yaw does not alter the optimal rotational speed of the ducted turbine. The turbine performance remains superior to non-yawed conditions up to a yaw angle of approximately 7°, peaking with a 1% improvement at 5°, but deteriorates beyond this point, declining by 1.5% at a yaw angle of 10°. In addition, yaw causes a deflection in the wake of the ducted turbine. This deflection increases with the yaw angle, reaching its maximum at a yaw angle of 10° with an angle of about 3.4°, before diminishing. The duct structure significantly influences this deflection, while rotor rotation has a minimal impact on wake deflection. [ABSTRACT FROM AUTHOR]

DC short-circuit current calculation is necessary to design and protect modular multilevel converter-based (MMC-based) multiterminal dc (MTDC) grids. In this article, a general and analytical short-circuit current calculation method is proposed for bipolar MTDC grids. For pole-to-pole (P2P) faults, the superposed fault equivalent network of the MTDC grid is first developed in the frequency-domain. Then, a decoupling method based on the network inductance ratio is proposed, which simplifies the high-order network into the superposition of several independent two-order RLC circuits. As a result, the short-circuit current can be expressed as the sum of the currents of these RLC circuits. For pole-to-ground (P2G) faults, the phase-domain dc line impedance considering the coupling effects is determined based on its modal-domain parameters, so that the P2G fault current can be calculated using the method of the P2P fault. The proposed method’s effectiveness is verified through simulations and experiments, and the calculation error is classified and analyzed. Compared with the existing methods, the proposed method is more accessible, more accurate, and available for hand-solution. [ABSTRACT FROM AUTHOR]

Waters surrounding Zhoushan Archipelago have the most abundant tidal current energy in China, which makes it a promising site for tidal farm construction in the future. Before deploying tidal current turbines, the potential environmental impacts on surrounding waters must be evaluated. In this work, we focus on the flow field impact assessment of an assumed tidal farm installed in Zhoushan Putuo-Hulu Channel. First, in order to evaluate the tidal characteristics there, a 2-month ADCP campaign is carried out, and a 3-D hydrodynamic model is established and validated with the in-situ measurements. Additionally, tidal current velocity and water depth as well as flow heading asymmetry information are used to evaluate the tidal stream exploitability within this channel. Second, a tidal farm consisting of 115 turbines is planned and assumed to be deployed throughout this channel. Blade element momentum method is used to numerically characterize the flow-turbine interactions, and then the spatial-temporal flow field variations caused by the assumed tidal farm are evaluated. It can be seen from the results that the peak flow speed reduction produced by the tidal farm could be over 0.5 m/s within the wake zones, while the flow velocity increment along two islands could reach 0.6 m/s. In particular, a flow speed phase shift phenomenon can be observed. Besides, the water level experiences a small overall rise, and the difference compared with the reference is within ± 3.0 cm. Moreover, the seabed shear stress within the wake zones could drop by 65%, while the areas along the two islands might see over 100% increase, indicating the risk of sediment deposition and coastal erosion. [ABSTRACT FROM AUTHOR]

Irradiation by light is considered to be one of the primary sources of damage to the cellulose matrix under environmental conditions. In this study, a laminated assembly method was used to coat 2, 4-dihydroxybenzophenone (UV-0) and hydroxypropyl cellulose (HPC) on the paper surface to form a light-shielding layer. The coating material was characterized by UV–vis and FTIR. The photostability of the coating treatment was further evaluated by comparing the measured values of UV–vis, infrared spectrum, degree of polymerization, tensile strength, folding endurance and chromaticity before and after accelerated aging for two kinds of paper samples. The results demonstrated that the coating treatment could significantly enhance the photodurability of cellulose-based materials with different pigments under accelerated UV aging conditions. • A laminated assembly coatings were applied to cellulose-based materials against UV irradiation. • The assembly composite mode shows much higher efficiency to shield the UV irradiation. • The assembly composite mode can well maintain the mechanical properties of the treatment sheet. [ABSTRACT FROM AUTHOR]

• Self-toughness porous Si 3 N 4 ceramics with 3D cage structures are prepared. • 3D cage structures can cause crack deflection to produce microcrack toughening. • No metallic oxide sintering aids exist in the as-fabricated porous Si 3 N 4 ceramics. • Si 3 N 4 ceramics own high mechanical strength and excellent dielectric properties. Self-toughness porous Si 3 N 4 ceramics are prepared by surface modification of Si 3 N 4 particles. The as-fabricated porous Si 3 N 4 ceramics have high number of three-dimensional cage structures that can cause the crack deflection, absorb the fracture stress to produce microcrack toughening effect and increase the structural reliability of porous Si 3 N 4 ceramics. The flexural strength is 78.0 MPa. The dielectric constant and dielectric loss is 3.47 and 0.001 respectively. This kind of porous Si 3 N 4 ceramics with special three-dimensional cage structures have high mechanical strength, good antioxidation properties and excellent dielectric properties. [ABSTRACT FROM AUTHOR]