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Pump-jet holds a pivotal position in various marine applications, underscoring the need for comprehending their transient behavior for the purpose of design enhancement and performance refinement. This paper employs Reynolds-averaged Navier–Stokes equations method in conjunction with Detached Eddy Simulation model. The study delves into the ramifications of accelerating and decelerating ducts, distinguished by camber f and attack angles α, on transient hydrodynamic characteristics. The hydrodynamic characteristics are investigated numerically, after the validation of the numerical methodology by comparing simulation outcomes against experimental results. Subsequently, the study delves into propulsion characteristics, followed by an exploration of time-domain and frequency-domain data transformed through fast Fourier transform to analyze thrust fluctuations and pulsating pressures. Additionally, a detailed examination of pressure distribution and velocity field is provided, aiming to dissect the mechanisms through the variations in f and α influence the flow field. Findings suggest that the outlet velocity of accelerating ducts significantly surpasses the inlet velocity, a behavior contrasted by decelerating ducts. Notably, the patterns of accelerating and decelerating ducts resulting from alterations in f exhibit consistent characteristics with those brought about by changes in α. However, several opposite characteristics surface in transient flow field due to the distinct modifications in the duct profile. Furthermore, by considering vorticity magnitude distribution and vortices, a comparative analysis elucidates the effects of varying f and α on rotor and stator trailing vortices. This contributes to understanding the flow instability mechanism under differing duct configurations. It is evident that changes in f and α exert significant influence on both performance and flow field. [ABSTRACT FROM AUTHOR]

The iron and steel industry is an important foundation of the national economy. It is the inevitable choice, to achieve high-quality development in the new era of the iron and steel industry, to speed up the green development of the iron and steel industry. This paper studies the effect of steel industry agglomeration on regional economic growth and air pollution. Through the analysis of the characteristics of iron and steel industry agglomeration, and the empirical analysis of the relationship between iron and steel industry agglomeration, regional economic growth, and air pollution, it is found that: (1) Iron and steel industry agglomeration helps to promote economic growth; (2) Iron and steel industry agglomeration has an obvious spatial correlation effect and obviously drives the development of surrounding areas; (3) Iron and steel industry agglomeration will cause air pollution. The marginal effect of air pollution will decline rapidly with the development of iron and steel industry agglomeration. (4) The impact of green process innovation investment on air pollution presents an inverted U-shaped effect, which has a positive effect on air recovery after exceeding the critical point. (5) The air self-purification capacity represented by precipitation, helps to reduce air pollution. Based on the above conclusions, this paper puts forward some policy suggestions, such as making a scientific development plan for the iron and steel industry, accelerating green process innovation, effectively improving regional precipitation and precipitation times, vigorously promoting high-quality development of the regional economy, and comprehensively promoting coordinated development of the iron and steel industry, so as to cope with the dilemma of the coordinated development of the iron and steel industry, regional economic growth, and smog pollution, and strive for international development in the future. In the competition, we should gain the first opportunity and obvious competitive advantage. [ABSTRACT FROM AUTHOR]

Metastability engineering of high entropy alloys can widen the alloy-design window through the access of a potentially huge configuration space. At the same time, it has the great capacity to overcome the strength-ductility trade-off, where often one witnesses an actual performance improvement at low to cryogenic temperatures. An in-depth microscopic understanding of the underlying mechanism is now needed to drive the design effort. Here we investigate in detail the energetic, structural and chemical complexity of Ti–Zr–Hf–Ta system. The large configuration space with local chemical interaction heterogeneity is explored by a combination of structure-searching techniques and accurate energy models constructed by cluster expansion based on density functional theory data. We find that the potential energy landscape evolves towards displaying shallow mega-basins when decreasing the Ta content. This is accompanied by an expansion of the configurational density of states, which evolves to be clearly distinct from that of a homogeneous random solid-state solution. Furthermore, the energy-state variability and local configuration flexibility are identified from high throughput analysis of atomic structures and their energies. Such features remind closely what found in glass-like systems. This work suggests a theoretical connection between glass physics and metastability engineering of HEAs is quite promising. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the effects of duct profile parameters cambers and angles of attack that distinguish accelerating and decelerating ducts on the flow characteristics of pump-jet. A detailed numerical analysis is carried out to compare the properties of pump-jets with different cambers and attack angles, and to explore the mutual interaction between the duct and components of pump-jet. Beforehand, the numerical methodology is validated by comparing the experiment and simulation results of the pump-jet under mooring conditions and propeller VP1304. Five cambers (f = 0.5t, 0.25t, 0, −0.25t, −0.5t) and three attack angles (α = 4°, 0°, −4°) of duct profile are considered carefully to distinguish accelerating and decelerating ducts, focusing on the propulsion performance and flow field information. The results show that the flow velocity at the outlet of the accelerating ducts is significantly higher compared to the inlet velocity, as opposed to the phenomenon produced by decelerating ducts. The variation of camber makes the internal evolution of the flow field more intuitive compared with the change of angles of attack. Further results indicate that the maximum efficiency of pump-jet drops after the modest growth as the cambers decrease, whose location shifts towards the lower advance coefficient J. The alteration of α leads to making the trend more direct and apparent for the decelerating and accelerating ducts. The high f is advantageous for the cavitation resistance of inside components, like rotor blades and stator blades. The impacts of changing α on the distribution of pressure in pump-jets with accelerating and decelerating ducts are more prominent than changing f. Moreover, the effects of both variations of f and α on the circumferential distributions of the velocity components are prominent, while there are still significant differences between these changes. Additionally, the velocity distribution at the inlet of pump-jets with decelerating ducts is higher than that at the outlet, and the velocity distribution of pump-jets with accelerating ducts presents the opposite pattern. • Contributing a comparative numerical simulation for the effect of the accelerating duct and decelerating ductdistinguished by different cambers and angles of attack. • Adopting experiment of noncavitating cases on propeller VP1304 and pump-jet with different rotator speeds under mooring conditions to verify the accuracy of the numerical simulation method. • Comparing single ducts with different cambers and angles of attack and flow characteristics of pump-jet with 2 types of ducts distinguished by different cambers and angles of attack. • Comparing and discussing the hydrodynamic performance curves, pressure distribution, and velocity distribution in pump-jet with different camber (f = 0.5t, 0.25t, 0, −0.25t, −0.5t) and angles of attack (α = 4°, 0°, −4°). [ABSTRACT FROM AUTHOR]

Human disturbance is one of the essential forces affecting changes in landscape patterns. Studying the relationship between human disturbances and landscape patterns is of significance for regional conservation and ecosystem management. An understanding of this relationship is also crucial for the mitigation of conflicts between socioeconomic development and environmental protection. In this study, using remote sensing data and geographical information system technology, we created a quantitative method to assess the intensity of human disturbance on the landscape by introducing the concept of hemeroby. By means of the measurement of hemeroby and statistical approaches, we quantitatively analyzed the temporal and spatial changes of human disturbances and their effects on landscape patterns in the Jiangsu coastal zone, China, from 1995 to 2013. The results showed that the intensity of human disturbance gradually increased from 1995 to 2013. While the increasing rate of intensity of human disturbance has slowed down from early period (1995–2002) to later period (2002–2013) because of differences in exploitation activities and regional development policies. Spatially, the hemeroby increased most obviously in the southern counties and northern Ganyu County, resulting from port construction and tidal flat reclamation. Depending on the different degrees of human disturbance, landscape patterns showed obvious differences. Compared with low-level and high-level human disturbance, mid-level human disturbance contributed to more fragmented landscape, more complex patch shape, lower connectivity, and higher diversity. A correlation analysis between landscape indices and hemeroby suggested that the landscape patterns in regions with high-level human disturbance were relatively sensitive to changes in the intensity of human activities. The findings in this paper provide additional spatial information and theoretical guidance for regional conservation and ecosystem management in the Jiangsu coastal zone, China. [ABSTRACT FROM AUTHOR]

In this paper, a real wind farm layout optimization is carried out by applying the novel optimized wind farm control strategy (coordinating wind turbine operations by setting different axial induction values) and multiple wind turbine hub height selections. The unrestricted coordinate method (using Cartesian coordinates to determine wind turbine positions) is applied to study the effectiveness of different wind farm control strategies and wind turbine hub heights on the wind farm optimization. Means of handling the irregular boundary constraints and calculating the wind speed over non-flat terrain at different heights are proposed for the real wind farm. The results show that the optimized control strategy can always yield better results than the self-optimum control strategy, achieving a smaller cost of energy production and a larger wind farm efficiency. Quantitatively, the optimized control strategy yields approximately 9 kW more power per turbine than the self-optimum control strategy and reduces the cost of energy by 0.08 million dollars per megawatt with 39 wind turbines installed. The application of different hub height turbines facilitates to place wind turbines more flexibly achieving better optimization results than that with constant hub height turbines. [ABSTRACT FROM AUTHOR]

We present a Chebyshev-Davidson method to compute a few smallest positive eigenvalues and corresponding eigenvectors of linear response eigenvalue problems. The method is applicable to more general linear response eigenvalue problems where some purely imaginary eigenvalues may exist. For the Chebyshev filter, a tight upper bound is obtained by a computable bound estimator that is provably correct under a reasonable condition. When the condition fails, the estimated upper bound may not be a true one. To overcome that, we develop an adaptive strategy for updating the estimated upper bound to guarantee the effectiveness of our new Chebyshev-Davidson method. We also obtain an estimate of the rate of convergence for the Ritz values by our algorithm. Finally, we present numerical results to demonstrate the performance of the proposed Chebyshev-Davidson method. [ABSTRACT FROM AUTHOR]

With the accelerating urbanization process in China, the extensive economic growth model with high energy consumption and high pollution aggravates atmospheric environmental pollution and restricts the sustainable development of the social economy. The Beijing–Tianjin–Hebei region has the most severe haze pollution and the most acute contradiction between resources, environment and economic development. Based on the physical coupling theory, this paper constructs a coupling coordination degree model of the economy, environment and high haze pollution industries, such as the thermal power industry. Through literature analysis and expert investigation of the economic, industrial and environmental data of the Beijing–Tianjin–Hebei region from 2006 to 2018, the coordinated development of the economy, environment and high haze pollution industries, such as the thermal power industry, in the above region, was dynamically monitored. The monitoring results show that the development level of the Beijing, Tianjin and Hebei region is significantly different, and the three subregions have not entered the stage of coordinated development. Moreover, since 2015, they have been in a bottleneck period of development and have not achieved a higher level of progress. The three subregions have different advantages and restraining factors. For example, the backward level of Hebei's economy and high haze pollution industries, such as the thermal power industry, restrict the coordinated development of the region as a whole. Only by accelerating the high-quality development of the Hebei economy can we break through the bottleneck of the development of Beijing, Tianjin and Hebei. [ABSTRACT FROM AUTHOR]

Abstract: A meaningful rank as well as efficient methods for computing such a rank are necessary in many areas of applications. Major methodologies for ranking often exploit principal eigenvectors. Kleinberg’s HITS model is one of such methodologies. The standard approach for computing the HITS rank is the power method. Unlike the PageRank calculations where many acceleration schemes have been proposed, relatively few works on accelerating HITS rank calculation exist. This is mainly because the power method often works quite well in the HITS setting. However, there are cases where the power method is ineffective, moreover, a systematic acceleration over the power method is desirable even when the power method works well. We propose a practical acceleration scheme for HITS rank calculations based on the filtered power method by adaptive Chebyshev polynomials. For cases where the gap-ratio is below 0.85 for which the power method works well, our scheme is about twice faster than the power method. For cases where gap-ratio is unfavorable for the power method, our scheme can provide significant speedup. When the ranking problems are of very large scale, even a single matrix–vector product can be expensive, for which accelerations are highly necessary. The scheme we propose is desirable in that it provides consistent reduction in number of matrix–vector products as well as CPU time over the power method, with little memory overhead. [Copyright &y& Elsevier]

Abstract: We study the eigenvalues of a matrix A perturbed by a few special low-rank matrices. The perturbation is constructed from certain basis vectors of an invariant subspace of A, such as eigenvectors, Jordan vectors, or Schur vectors. We show that most of the eigenvalues of the low-rank perturbed matrix stayed unchanged from the eigenvalues of A; the perturbation can only change the eigenvalues of A that are related to the invariant subspace. Existing results mostly studied using eigenvectors with full column rank for perturbations, we generalize the results to more general settings. Applications of our results to a few interesting problems including the Google’s second eigenvalue problem are presented. [Copyright &y& Elsevier]

Abstract: Estimating upper bounds of the spectrum of large Hermitian matrices has long been a problem with both theoretical and practical significance. Algorithms that can compute tight upper bounds with minimum computational cost will have applications in a variety of areas. We present a practical algorithm that exploits k-step Lanczos iteration with a safeguard step. The k is generally very small, say 5–8, regardless of the large dimension of the matrices. This makes the Lanczos iteration economical. The safeguard step can be realized with marginal cost by utilizing the theoretical bounds developed in this paper. The bounds establish the theoretical validity of a previous bound estimator that has been successfully used in various applications. Moreover, we improve the bound estimator which can now provide tighter upper bounds with negligible additional cost. [Copyright &y& Elsevier]

Abstract: We propose a block Davidson-type subspace iteration using Chebyshev polynomial filters for large symmetric/hermitian eigenvalue problem. The method consists of three essential components. The first is an adaptive procedure for constructing efficient block Chebyshev polynomial filters; the second is an inner–outer restart technique inside a Chebyshev–Davidson iteration that reduces the computational costs related to using a large dimension subspace; and the third is a progressive filtering technique, which can fully employ a large number of good initial vectors if they are available, without using a large block size. Numerical experiments on several Hamiltonian matrices from density functional theory calculations show the efficiency and robustness of the proposed method. [ABSTRACT FROM AUTHOR]

We revisit the two standard dense methods for matrix Sylvester and Lyapunov equations: the Bartels-Stewart method for A1X + XA2 +D = 0 and Hammarling's method for AX + XAT + BBT = 0 with A stable. We construct three schemes for solving the unitarily reduced quasitriangular systems. We also construct a new rank-1 updating scheme in Hammarling's method. This new scheme is able to accommodate a B with more columns than rows as well as the usual case of a B with more rows than columns, while Hammarling's original scheme needs to separate these two cases. We compared all of our schemes with the Matlab Sylvester and Lyapunov solver lyap.m; the results show that our schemes are much more efficient. We also compare our schemes with the Lyapunov solver sllyap in the currently possibly the most efficient control library package SLICOT; numerical results show our scheme to be competitive. [ABSTRACT FROM AUTHOR]

We propose an approximate implicit subspace iteration with alternating directions framework for linear time-invariant system model reduction. Within this framework, dominant eigensubspaces of the product of the system Gramians are approximated directly. This has advantage over approaches that consider the system Gramians separately. We construct two methods within the framework, one uses the QR updates and the other uses the SVD updates. Numerical results show the efficiency of the proposed methods. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The power of density functional theory is often limited by the high computational demand in solving an eigenvalue problem at each self-consistent-field (SCF) iteration. The method presented in this paper replaces the explicit eigenvalue calculations by an approximation of the wanted invariant subspace, obtained with the help of well-selected Chebyshev polynomial filters. In this approach, only the initial SCF iteration requires solving an eigenvalue problem, in order to provide a good initial subspace. In the remaining SCF iterations, no iterative eigensolvers are involved. Instead, Chebyshev polynomials are used to refine the subspace. The subspace iteration at each step is easily five to ten times faster than solving a corresponding eigenproblem by the most efficient eigen-algorithms. Moreover, the subspace iteration reaches self-consistency within roughly the same number of steps as an eigensolver-based approach. This results in a significantly faster SCF iteration. [Copyright &y& Elsevier]

We study Davidson-type subspace eigensolvers. Correction equations of Jacobi-Davidson and several other schemes are reviewed. New correction equations are derived. A general correction equation is constructed, existing correction equations may be considered as special cases of this general equation. The main theme of this study is to identify the essential common ingredient that leads to the efficiency of a diverse form of Davidson-type methods. We emphasize the importance of the approximate Rayleigh-quotient-iteration direction. [ABSTRACT FROM AUTHOR]

Pump-jet propulsion, a new propulsion technology, is primarily designed for underwater vehicles. Because of its concealment and excellent performance, it has been widely used, but due to its confidentiality and complexity, few studies have been published. To explore the relevant design theory of pump-jet propulsion with the aim of increasing its performance, in this study, we applied the direct and inverse design methods to construct a three-dimensional pump-jet model. The direct design method was carried out by comparing the lifting and lifting-line design methods, followed by further geometric optimization of the better model. In a numerical study using computational fluid dynamics (CFD) simulations, the Reynolds Averaged Naviere-Stokes (RANS) equations with SST k-ω turbulence model were solved in a cylindrical computational domain around the pump-jet propulsion device. A numerical investigation of the E779A propeller was carried out beforehand, using different advance ratios, in order to validate the accuracy of the numerical simulation method. The results show that for the direct method, although the model designed using the lifting-line method produced a greater thrust and the pump-jet designed using the lifting method was more efficient and stable, which is more suitable for small and medium underwater vehicles. When considering the inverse design method, the pump-jet propeller obviously accelerated the fluid, and the speed was obviously greater than that designed using the direct design method, while the turbulent kinetic energy in the flow field was higher, as well as the energy loss. Therefore, for small- and medium-sized underwater vehicles, if the priorities are high thrust and high efficiency, the inverse design method is the best option, whereas if stability and lower energy loss are preferred, the direct design method should be adopted. [ABSTRACT FROM AUTHOR]

Because the Three Gorges Dam (TGD) has disturbed the normal hydrological regime downstream, analyzing the influence of the TGD on water level fluctuation is of great importance to ecological planning. The distribution and dynamic of the water level before and after the TGD were analyzed using frequency distribution and a complex network. Frequency distribution was unimodal before the TGD, and the peak ranged from 13–15 m. Frequency distribution was bimodal after TGD and two peaks ranged from 9–10 m and 16–17 m. The number of days when the water level was above warning level was reduced, and it was increased when the water level was below the ecological level. Further, the TGD had little effect on the number of days of rapid water level rising, which mainly existed during the flood season. However, this imposed a greater influence on the number of days of rapid water level decline, which implies a weaker intensity of the recession process, along with a longer duration. Thirdly, in winter and spring, the water level after the TGD was lower than that before the TGD by approximately 1 m. In summer, the number of days when the water level was above warning level was reduced. In autumn, the frequency distribution changed from unimodal to bimodal. The TGD has the greatest influence during the winter, which resulted in a lower water level and more severe drought. [ABSTRACT FROM AUTHOR]

Abstract This paper aims to systematically study the wind farm optimization with the continuous selection of wind turbine placement (using Cartesian coordinates) and wind turbine hub height (restrained among a predefined range). Two case studies are performed. The first case involves an ideal two-dimensional (i.e., flat terrain) wind farm, and the other is a three-dimensional wind farm with real terrain altitudes. The schemes of simultaneously optimizing the wind farm layout and wind turbine hub heights applying the simplified and augmented PARK wake model are established for the ideal and real wind farm cases, respectively. The results show that applying different wind turbine hub heights for the wind farm layout optimization yields significant improvement: up to a 0.2 MW increase in total power and a 2% increase of the wind farm efficiency for the ideal wind farm. However, for the real wind farm the effectiveness of applying different wind turbine hub heights varies depending on the number of turbines installed. With less number of turbines installed, the impact of varying hub heights is small. However, significant improvements can be achieved as the number of turbines increases. With 39 wind turbines, the wind farm cost of energy can be reduced by $15000 per megawatt and the wind farm efficiency can increase by up to 0.2%. Given the nameplate capacity and the lifespan of wind farm project, the resulting effect on total energy production can be significant and thus improve the competitiveness of wind power exploitation. Highlights • A combined optimization of wind turbine positions and hub heights is conducted with continuous variation. • A computationally-efficient method considering wake effect over non-flat terrain is applied. • Ideal wind farm yields 0.2 MW more power and 2% increase in efficiency with maximum hub height difference of 40 m. • Real wind farm reduces cost of energy by $15000 per megawatt with maximum hub height difference of 40 m. [ABSTRACT FROM AUTHOR]

Abstract The wind farm layout optimization is an effective tool to alleviate the wake power losses caused by wind turbine interactions in a wind farm. It is widely recognized that for a real wind farm site with abundant wind resources, wind speed variation of the wind condition can be approximated by the Weibull distribution, which therefore needs to be incorporated into the power evaluation of a real wind farm design. Current researchers have employed the discretization method by dividing the wind speed region into bins to calculate the power output of wind turbines under Weibull distribution, which has two main drawbacks including: 1) complicated discretization process with large computational cost and 2) dependency of calculation accuracy on the discretization resolution. This paper aims to propose a new Monte Carlo method to evaluate the wind farm power output under Weibull distribution, and verify the effectiveness and efficiency of the new method by comparison to the widely used discretization method. Through reducing the wind speed discretizing interval, it is found that when the discretized wind speed interval is smaller than 0.1 m/s, the improvement of optimization results is negligible while the computational cost significantly increases for the discretization method. By testing different sample numbers, it is found that selecting 100000 samples for the Monte Carlo method calculation is able to achieve accurate results with less computational cost than the discretization method especially when large number of turbines is installed in the wind farm. In conclusion, the Monte Carlo method greatly facilitates the power evaluation of wind farm layout optimization under Weibull distribution, with a balance between the calculation accuracy and the computational cost. Highlights • A novel Monte Carlo method for evaluating wind farm power under Weibull distribution is proposed. • Different wind speed discretizing intervals of discretization method for evaluating total power are tested. • Comparison of effectiveness of discretization method and Monte Carlo method is made. • When discretization is less than 0.1 m/s, improvement is negligible but cost significantly increases. • Monte Carlo method greatly facilitates wind farm layout optimization under Weibull distribution. [ABSTRACT FROM AUTHOR]

Characterization of phosphorus (P) pools is vital to understanding the contribution of P to water eutrophication. In this study, dissolved and particulate P classes during an algae bloom in Lake Taihu, as well as their relationships with the main environmental factors, were analyzed based on solution 31 P NMR. The results showed that dissolved P was dominated by orthophosphate (Ortho-P) in heavily polluted regions and by orthophosphate monoester (Mono-P) and orthophosphate diester (Diester-P) in lightly polluted regions, indicating that the main dissolved P classes varied with the degree of lake pollution. The difference in the temporal variation patterns of dissolved P classes revealed that dissolved Ortho-P is the preferred class, and its concentration may be affected by major primary producers. It also revealed that dissolved Mono-P is prone to accumulation under the effects of algal blooms, especially in heavily polluted regions. The main particulate P classes were similar to those of dissolved P, but their variation trends were the same in different lake regions. There were significant positive correlations between the major particulate P classes and Chl a during the majority of the sampling period, indicating that living algal cells have a major contribution to particulate P. Obvious temporal variations of P classes may affect the bioavailability and dynamics of P in the water of Lake Taihu, but the particle reactivities of the main inorganic and organic P classes were similar. Therefore, they have little effect on P partitioning between the dissolved and particulate phases. [ABSTRACT FROM AUTHOR]

The hot deformation behavior, hot workability and dynamic recrystallization evolution of Zr–1.0 (wt%) Be alloy in single α phase were investigated by conducting hot compression tests. The strain rates ranging from 10 –3 s –1 to 10° s –1 and testing temperatures varying from 650 °C to 850 °C were used. Flow stress was found to increase with increasing strain rate and decrease with the increment of the deformation temperature. A constitutive equation of flow behavior was established to describe the dependence of flow stress on strain rate and deformation temperature. The activation energy for deformation of Zr–1.0Be alloy was determined to be Q =301 kJ/mol. The processing map of Zr–1.0Be alloy was constructed at strain rates ranging from 10 –3 s –1 to 10° s –1 and deformation temperatures varying from 650 °C to 850 °C at the true strain of 0.7. A processing map was used to identify the best domains of thermal processing, including a domain at a temperature of 650 °C and strain rate of 10 –3 s –1 , as well as another domain at deformation temperatures ranging from 800 °C to 850 °C and strain rates varying from 10 –3 s –1 to 10 –1 s –1 . Microscopic analysis of Zr–1.0Be alloy showed that the flow instability and kink were very obvious at low temperatures and high strain rates. At high temperatures and low strain rates, the dynamic recrystallization became the main softening mechanism during hot working. [ABSTRACT FROM AUTHOR]

• Stable isotope technique was applied to study water use strategy of wetland plant. • The main water source of Carex cinerascens was changed from lake water to soil water. • Water conditions strongly adjusted WUE and water niche of Carex cinerascens. • Carex cinerascens had obvious adjustability and adaptability. Water is a key factor in maintaining plant growth and determining plant species distribution. Studying the water use strategies of plants under different water conditions is of great significance for understanding the wetland vegetation patterns and performing ecological regulation of wetlands. The present study aims to quantify the contribution rates of potential water sources to Carex cinerascens in the Poyang Lake Wetland using stable isotope techniques and to assess water use efficiency (WUE) and water niche breadth to reveal the water use strategy of C. cinerascens and its response to water condition changes. The results showed that soil water in the 0–20 cm soil layer replaced lake water, becoming the main source of water for C. cinerascens during the growing season as a result of the decrease in the lake water levels and the change in soil water contents. The contribution rates of soil water in the 0–20 cm soil layer to the development of C. cinerascens in the 12-, 13-, and 14-m elevation zones increased by 31.4, 11.0, and 21.1 %, respectively. In addition, the contribution rate of soil water from the 20–40 cm soil layer was lower than that from the 0–20 cm soil layer, while rainwater exhibited the lowest contribution rates to the development of C. cinerascens. The aboveground parts exhibited higher WUE values than those of belowground parts at the growth stage, except in the 14-m elevation zone, and lower WUE values than those of the belowground parts at the maturation and wilting stages of C. cinerascens. According to the calculated Levins index, the water niche breadths of C. cinerascens were reduced and increased under abundant and insufficient water amounts, respectively. C. cinerascens adjusted the water source, WUE, and water niche breadth during the entire growing season to adapt to changing water conditions in the Poyang Lake Wetland, thereby reflecting the strong adjustability and adaptability of C. cinerascens. This study provides further insights into the relationships between wetland vegetation and hydrological changes, as well as a scientific basis for wetland ecological and hydrological regulation and vegetation restoration in the Poyang Lake Wetland. [ABSTRACT FROM AUTHOR]

Application of gallium-based liquid metals below 273 K calls for design of novel metastable materials with exceptionally low melting points. It is crucial to develop the thermodynamic database of metastable phases and to unveil their trapping mechanism. In this work, the thermodynamic assessment of metastable β-Ga and its lattice stability were evaluated by integrating experimental and ab-initio thermodynamics. We demonstrated that the lattice stability expression derived from a high-order modified Einstein modeling with anharmonic correction provided the most reliable and the most accurate description hitherto. Thereafter, the critical radius and the work for nucleation were derived by applying our optimized expressions of lattice stability and surface energy. Thereby the capturing of β-Ga at nano sizes and high supercooling were well explained. And it was confirmed that the classical nucleation theory played an important role in trapping metastable β-Ga phase. Furthermore, the significance of surfaces and interfaces in solidification process were highlighted. This work sheds light on designing metastable liquid metals with low melting points. Moreover, it provides a novel workflow for future studying of metastable multicomponent alloys. [ABSTRACT FROM AUTHOR]

A large area of the continents is covered by loess that is subject to fast erosion, but detailed research is lacking about processes influencing the hydrogeochemistry in loess-covered regions. This study presents the first δ 18 O and δD, and major ion contents of various waters (rain, rivers, lake, springs and wells) from Daihai Lake catchment on the Chinese Loess Plateau (CLP). In combination with historical hydrological and meteorological data during the past 60 years, we investigate factors affecting water chemistry and lake evolution on the CLP, and thereby provide insight into hydrogeochemical processes under semi-arid climatic conditions. On the northeast CLP, river and groundwaters show elevated TDS (450 and 461 mg/L, respectively), about ~ 4 times higher than the global river mean value. Their water chemistry is dominantly influenced by carbonate weathering. Lake waters show even higher TDS at 5758 mg/L, ~ 50 times of the global mean, which is attributed to strong evaporation and associated with precipitation of calcite and dolomite. The order of carbonate (calcite and dolomite) saturation indexes follows lake water > river water > groundwater. Downstream rivers to the west of Daihai Lake are characterized by elevated SO 4 2 − , indicating high lake levels in the past. Comparison of δ 18 O, δD, TDS and ion contents of river and groundwaters implies that shallow groundwaters are derived from surface runoff via fast infiltration, a hydrological process different from limited infiltration of groundwater on the Tibetan Plateau. Water quality assessment indicates that all river and 79% of well waters belong to moderately hard to hard-fresh waters, suitable for drinking and irrigation of plants with moderate salt tolerance. In contrast, all lake and spring waters and 21% of well waters belong to very bad water quality, and hence are not suitable for irrigation or drinking. Owing to intensified human activities under drying and warming climate, the lake water level of Daihai declined by 4.83 m from 1955 to 2003, and started to accelerate since 1980. As a result, TDS and Cl − increased by 1.8 times and Mg/Ca rose by 156 times from 1953 to 2010. Our data show that environment degradation poses a great threat to human occupation on the CLP. Considering the uniformity of loess, hydrogeochemical processes between surface and groundwaters on the loess regions may represent a widespread status of the CLP. [ABSTRACT FROM AUTHOR]

Wind farm layout optimization results depend on the optimization objectives, such as power output and variance. This paper investigates an alternative strategy for wind farm layout optimization by trading off the mean wind power output and power variance. Two optimization schemes, the weighted optimization and confidence interval optimization are compared in term of their performances on trading off energy-variance. For the weighted optimization, the objective function weight value α varies from 0 to 1 (implying the optimization objective shifts its weight from the power variance to the power output), while for the confidence interval (CI) optimization, either the lower or the upper limit of power output CI is maximized/minimized. It is found that the CI maximization achieves a trade-off of mean power output and power variance similar to the weighted optimization with α ≥ 0.6 , and the same individual power output range (192 kW–207 kW) is obtained with staggered placements of wind turbines. The CI minimization obtains a trade-off of average power output and power variance close to the weighted optimization with α ≤ 0.4 , and the optimal wind turbine locations are aligned. The advantage of CI optimization lies on its capability of predicting the power output uncertainty. • Wind farm layout optimization trading-off the mean and the variance of the power output is conducted. • Two optimization schemes (weighted and confidence interval optimization) are compared. • CI maximization achieves a trade-off similar to the weighted optimization with α ≥ 0.6. • CI minimization obtains a trade-off close to the weighted optimization with α ≤ 0.4. • The advantage of CI optimization lies on its capability of predicting the power output uncertainty. [ABSTRACT FROM AUTHOR]