As an emerging interdisciplinary concept, environmental computing is a term used for the quantitative research process of environmental process numerical analysis and (or) environmental data analysis based on computing. Under this conceptual framework, various kinds of environment and computational science integrations are discussed together for ensuring development in this field as well as summarizing advanced research models and methods. This paper introduces the definition and basic characteristics of environmental computing and explains the methodological characteristics of various types of environmental computing based on typical cases. Environmental computing has transitioned from theory-driven to data-driven and then to hybrid computing. The comprehensive computing framework shows considerable advantages compared to conventional approaches or single methods. To achieve significant breakthroughs, researchers need to constantly explore basic theories, including environmental and computational theories, and promote the transformation of environmental thinking to adapt to the frontier content of computational science. Additionally, challenges such as big data theory, technical application scenarios, and computing power also need to be overcome.

A large number of studies have presented methods using online resource management to optimize stream computing for fluctuating data streams, but have not optimized the parallel operator operations at the streaming application level. For example, in Apache Storm, the operator parallelism cannot be dynamically adjusted once it is set. This paper presents an intelligent parallelization strategy for operators with fluctuating data streams, As-Stream, which significantly improves the streaming computing platform performance. This method uses real-time tuning of parameters based on unsupervised learning and self-adaptive analyses in an elastic intelligent monitoring module. As-Stream includes parallel bottleneck identification, parameter plan generation, parameter migration conversion and parameter migration scheduling algorithms. The system was implemented on an Apache Storm platform with a large number of tests in a real distributed stream computing environment. The results show that this system significantly improves the performance compared with existing default scheduling strategies. With sufficient resources, the average throughput is increased 2.4 fold while with limited resources, the average latency is reduced by 44%.

With the continuous expansion of data centers, the problem of large energy consumption has become increasingly prominent. Distributed data centers can enable power transfer through the distribution of computing tasks among multiple data centers and realize the balance between power consumption and computing delay through the power control of a single data center. Scheduling of computing tasks and power control of data center interact with each other, and their control effects are affected by multiple uncertainties. Therefore, a fast and reliable control method is required for realizing the collaborative optimization of the information and energy layers of the data center. First, a distributed data center collaborative optimization architecture is constructed. Then, the dynamic characteristics of multiple data center computing task allocation and single data center power optimization are analyzed based on the dynamic differential equation, and a unified adjustment model of the coupling optimization problem is constructed. Given the system operating cost and computing delay in constructing the objective function, the optimal control theory is introduced to solve the problem and realize the second-level collaborative optimal control of the information energy of the data center. Simulation results show that the high-frequency control based on the proposed algorithm can better track the fluctuation of renewable energy output and calculation tasks than the minute-level control and effectively improve the economic benefits of the system and the local consumption rate of renewable energy.

This study analyzed the collimator parameters of a large animal single photon emission computed tomography (SPECT) detector. Six collimator design schemes were chosen by thoretical calculation of the spatial resolution, the sensitivity at the field of view (FOV) center and the projection overlap ratio with specified constraints. A performance evaluation method was used to evaluate the six collimator design schemes by calculating the contrast recovery coefficient (CRC) and the variance of the local impulse response of selected pixels to find the best design scheme. The imaging effect of the design scheme was verified by numerical simulations of imaging experiments of a hotrod phantom. The theoretical calculations and the numerical simulations demonstrate that the design scheme gives a spatial resolution of the hotrod phantom that is better than 3.0 mm with better than 0.03% sensitivity at the FOV center, which meets the technical requirements.

Information model is a new collaborative management tool applied to modern engineering design, construction and project management. Based on the problems of incomplete expression of information model and poor circulation of information data during the construction period of water conservancy and hydropower projects, advanced information technology is integrated with the construction process of a super-high arch dam in the context of increasingly frequent iterations and updates of new information technology such as internet of things, big data, block chain and artificial intelligence. The information management system developed here is based on building information modeling (BIM) and information modeling of all the design and construction stages of the super-high arch dam and is used to study information model development and implementation using a modern information model management platform for super-high arch dam construction scheduling, quality and safety and contract using Visual C# network programming technology. The system developed for the 300 m grade Baihetan dam has intelligent management of the entire dam design and construction stages and improved the problems of scattered information and low flow efficiency of hydropower projects in traditional mode, facilitated the control of construction progress and quality, assisted accurate construction and technology optimization, and promoted the development of project management and industry technology.

The regulating effect of check dams on the sediment transport in a watershed is important for improving soil and water conservation and watershed management of the Loess Plateau. The effect of a single check dam during flooding is studied here using a one-dimensional non-equilibrium sediment transport model for the Chabagou watershed of the Loess Plateau. The results show a power function relationship between the runoff erosion rate and the sediment transport modulus for cases with and without a check dam, but the relationship with no check dam cannot be extended to cases with a check dam due to the regulating effect of the check dam. The regulating effect of the check dam varies with the flood recurrence frequency and the siltation stage. Furthermore, there is a threshold siltation rate above which the check dam does not trap sediment during flooding. The threshold siltation rate changes from 88.3% to 93.6% for a catastrophic flood to a regular flood. This study shows that the widely used empirical constant threshold siltation rate is only applicable to small floods.

An equivalent pore network model (EPNM) describes complex pore structures in a porous media by statistical parameters. Previous studies using such models have focused on seepage and mechanical dispersion, with few studies considering the effect of molecular diffusion on solute transport. In this study, the convection, molecular diffusion and mechanical dispersion of solutes in porous media were studied using an EPNM to predict the solute transport in porous media. A sensitivity analysis of the model parameters was used to study the effect of the pore structure characteristics on the effective diffusion coefficient of the porous media. The influence of molecular diffusion on the hydrodynamic dispersion was analyzed by comparing numerical results with and without molecular diffusion. The results show that the effective diffusion coefficient, which negatively correlates with the throat curvature and positively correlates with the coordinate number and the connection number ratio, is affected by both the pore volume and the pore-throat diffusion capacity. The molecular diffusion correlates with the convection-induced mechanical dispersion to accelerate the solute transport in the low-velocity region. The results of this study show the microscopic mechanisms influencing molecular diffusion for hydrodynamic dispersion as a theoretical basis for predicting the solute transport flux in pore network models.

The group analytic hierarchy process (AHP) was used with boxplots and Spearman's rank correlation coefficient analyses. The relevant parameters of the hierarchy of decisions were calculated with Python. This multi-criteria decision-making model was then built. Previous investigations have not been reliable and the basic AHP is not always consistent. This Group AHP was then used to compare various vibro-stone column packing methods for treating the deep overburden dam foundation of a hydropower station in southwest China. The results show that the various project participants have different preferred technical routes. Designers and researchers are more inclined to choose innovative technical methods; while owners, constructors and supervisors are more inclined to use mature, reliable schemes. An intelligent feed device and a method were developed, which improve the quantity accuracy and the quality of the vibro-stone column filler for the deep overburden dam foundation.

An airborne image velocimetry (AIV) system is developed for field measurements of long river reaches based on ground control points placed along both riversides and tracking particles seeded onto the water surface. Image frames are taken by an unmanned aerial vehicle in cruise flying mode and stabilized by orthorectification and georeferencing using structure from motion (SfM). Particle image velocimetry is applied to velocity field computation, resulting in a panoramic velocity field. Applications of AIV in urban and rural areas produce high coverage of velocity fields with a high spatial resolution, enabling a detailed description of the flow characteristics. The relative errors of the streamwise velocity components of AIV are ?0% and ?% compared with that of the acoustic Doppler current profiler (ADCP) and flow meter, respectively, which meet the accuracy requirements of field measurements. Overall, with its high reliability and strong applicability, the AIV system could conduct large-scale velocity field measurements with high spatial resolution in long river reaches.

Vane pumps convert mechanical energy into fluid energy with the impeller being the key component. This paper designed a flow pump impeller using iterative solutions of direct and inverse problems. The velocity moment distribution along the axial streamline is controlled by a quartic function determined by the midpoint and outlet slope of velocity moment. Analyses of the influence of the velocity moment distribution on the impeller performance show that increasing the midpoint of velocity moment increases the load from the blade inlet to the middle which improves the pump work. The midpoint of velocity moment mainly affects the relative velocity distribution near the blade tip and the axial velocity in the middle of the impeller. The design was evaluated in energy and cavitation experiments. The high-efficiency operating range of the pump is flat and wide with a highest efficiency of 82.17%. The cavitation specific speed is 1 289.

Start-up transients in mixed-flow pumps are very complex due to the flow variations and rotational stall during start-up. A transient head equation was solved with a pipe resistance equation in this study to give a theoretical model for the varying flow rate and head during start-up of a mixed-flow pump. The model included the rotational acceleration to predict the variation of the flowrate and head during start-up. The start-up was also modeled with a three-dimensional numerical model of the mixed-flow pump and pipe system to predict the transient pump characteristics. The model predictions agree well with the numerical results to validate the theoretical model. During start-up, the flowrate does not increase as fast as the speed but continues to slowly increase after the pump has reached the maximum rotational speed. The transient pump head can be divided into the steady-state head, the acceleration head and the inertia head with the acceleration and inertia heads greatly influencing start-up.

High-elevation catchments are critical indicators of the earth's response to global warming. This study collected water chemistry data for runoff in the Yellow River source region from 2002 to 2019 to reconstruct the chemical weathering processes. From 2002 to 2019, the temperature in this region increased significantly along with the precipitation and runoff. The annual chemical weathering rates in this region ranged from 30.9 to 78 t穔m^-2, with an average of 53.2 t穔m^-2, which is more than twice the average chemical weathering rate of all global rivers. The annual chemical weathering processes in this region increased with increasing temperature at a rate of 1.13 t穔m^-2/a. In the context of global warming, the Tibetan high-elevation catchments play important roles in the material exchanges between the land and the oceans and contribute to the stabilization of atmospheric CO₂.

Vegetation plays an important role in controlling hillslope erosion but how the vegetation controls the soil erosion is still not well understood. The interactions between the soil detachment capacity and the sediment transport capacity were modeled in a hillslope erosion model that integrates vegetation effects. Runoff plot data in typical watersheds on the Loess Plateau were used to validate the model with coefficients of determination values ranging from 0.84 to 0.94, Nash-Sutcliffe simulation efficiencies (NSE) ranging from 0.83 to 0.93 and relative errors ranging from -16.1% to 14.2% for various land uses. The original module in the digital Yellow River integrated model (DYRIM) had coefficients of determination ranging from 0.01 to 0.51 and NSE ranging from -74.45 to 0.48. Thus, the new model is more accurate for various land uses and vegetation types with the absolute values of the simulated sediment discharge rates reduced by 13%-96%. This model can be applied to the Loess Plateau and can be integrated into DYRIM and other distributed hydrological and sediment coupled models.

Rapid urbanization has changed the structure of urban land use which has led to changes in evaporation rates in urban areas. Evaporation mechanisms include the common evaporation from the underlying urban surface as well as evaporation inside buildings. Urban surfaces can be divided into road, green spaces, water surfaces and buildings. This paper analyzes evaporation rates for the urbanization levels in six Beijing districts during 2000, 2015 and 2018. Both natural evaporation and the water dissipation inside buildings are considered to analyze the impact of urbanization and non-capital functions relief on the urban regional evaporation. The results show that urbanization significantly enhances the evaporation from urban construction land and the population density is the key factor affecting the evaporation. The deconstruction of the non-capital function reduces the urban social water use and the urban regional evaporation. This analysis of the contributions from the various underlying surfaces to the regional evaporation shows that buildings and green spaces provide most of the evaporation.

The Chinese construction industry is transforming into a new stage with high-quality developments. The incentive mechanism is an important project management tool, especially when pursuing project excellence and sustainability. However, existing research on incentives has mainly focused on descriptions of the applications and strategies, with little information on the mechanisms. This research developed a conceptual model of the interorganizational incentive mechanism which was verified by empirical questionnaire data from Chinese engineering firms and the partial least squares structural equation method. The analysis results showed light on the interorganizational incentive mechanism and the relation to interorganizational relationships, project resources, organizational capabilities, and project performance. The results showed that interorganizational incentives not only directly improve project performance, but also indirectly improve project performance by improving interorganizational relationships as well as project resource supplies. The results highlight the importance of turning cooperative relationships into project resources and turning resources into organizational capabilities. This research provides a theoretical basis for promoting incentives in China's construction industry and provides practical guidance for applying incentives in construction projects.

Real-time monitoring of the friction coefficient of the moving parts of a machine system is a challenging problem. The development of intelligent perception and data technology provides the possibility to use tribological correlation information to predict the friction coefficient. This paper uses multi-source friction information such as sound during the friction and wear test to form a time-sectioned friction information data set, establishes a K-fold cross-validation double-stacked regression integration model, defines the evaluation indicators for scope evaluation, and the model was tested with a variety of load test data. The results showed that the model can effectively refine the correlation characteristics of friction information, so as to accurately fit and predict the friction coefficient, and has universality for data under different load conditions.

Error compensation is an important means to improve the machining accuracy of NC machine tools. In this study, a three-coordinate measuring machine is used to measure the x, y, and z coordinates of points on the surface of a hexagonal groove after machining, and the contour error is calculated according to the ideal model. Next, based on mirror anti-deformation, the contour error at the midpoint of the tool point connection is compensated to obtain new NC data. The results indicate that after error compensation, the maximum absolute value of contour error of parts is reduced by 48.1%, and the machining accuracy is considerably improved. The compensation method of NC data based on contour error has strong applicability to parts composed of linear machining paths. Considering the midpoint of the tool point connection as the compensation object is conducive to error measurement and program design.

The sealing performance of safety valves relies on a tight fit between the spool and the seat. To avoid jamming, a larger fitting clearance is designed for spool guidance, which makes the spool deflection excessive, leading to a gap in the sealing interface and affecting the sealing performance. Based on ABAQUS, this paper conducts a mechanical analysis of the sealing interface under the conditions of spool deflection and studies the relationships between the spool deflection angles and sealing failure. By analyzing the simulation results, the maximum deflection angles of the spool are determined under the premise of ensuring the sealing performance at different operating temperatures. A complete simulation calculation method is proposed for the study field of valve sealing. The results provide a theoretical basis and reference for the design of fitting clearance and sealing part size of the valve.

Effective ship block yard scheduling is important for managing logistics costs in block construction. However, previous storage yard models have not been able to accurately describe the turns of flat transporters in storage yards which limits the scheduling effectiveness. Such scheduling strategies are only applicable to improving the efficiencies of small storage yards. A storage yard graph model was developed in this study with a node that integrates the cell position and the pose of the flat transporter so that the turns are accurately described. A fast, three stage strategy was then used to solve the scheduling scheme. The inbound block cell assignment is improved by decoupling the inbound order from the assignment order and incorporating an obstructive block prediction algorithm. Simulation of multi-yard scheduling in a shipyard scale model reduced the unproductive yard transfer rate to 10%, which shows the effectiveness of this storage yard model and the three-stage scheduling strategy.

The grounding grid plays a vital role for ensuring reliable power system operations. However, the buried environment around the grounding grid can result in grounding device defects, so the grounding grid must be periodically tested. This paper presents a SH guided wave detection method based on linear frequency modulation excitation and synchrosqueezed wavelet transforms for grounded flat steel power systems. The system uses a permanent magnetic array SH guided wave transducer which is simple and suitable for flat steel structures. The transducer is excited with a linear frequency modulation signal with synchrosqueezed wavelet transforms used to analyze the signal. Identification of the overlapping guided wave signals in the time-frequency plane effectively distinguishes between various defects and end faces. Signals from finite element simulations and experiments were then used to evaluate the signal analysis method. The calculated distance errors were all within 3%, which shows that the method can accurately extract the guided wave travel times and accurately locate defects. Comparisons with results using short-time Fourier transforms and Wigner distributions show the advantages of the time-frequency aggregation of the synchrosqueezed wavelet transforms.

The accuracy of using beam elements to model the stresses in stepped rotors is improved in this study by using cone-shape equivalent beam elements with shapes based on the bending stiffness. The bending stiffness of sections with abrupt changes was calculated in ANSYS using 3-D solid elements. The optimal size of the equivalent beam element was obtained using a least squares procedure. The calculations were used to relate the equivalent beam element size to the stepped rotor size. The calculations also related the equivalent beam element size to the integral disk size. The accuracy of the equivalent beam size models was then verified by rotor dynamics analyses. The results show that the critical speeds obtained using the equivalent beam elements agree better with the reference values in this paper than the results of both traditional beam models without equivalent segments and the 45?equivalent beam method.

The mechanical behavior of irradiated RPV steel is important for nuclear reactor safety. The property changes are due to microscale dislocation motion and interactions between dislocations and irradiation defects that need to be further understood. This study used molecular dynamics studies to model the interactions between 1/2[111] edge dislocations and [010] dislocation loops in BCC-Fe. The models show the effects of temperature and dislocation loop radius on the interactions and the critical resolved shearing stress (CRSS). The results indicate that the interactions include the formation of mixed dislocation segments, sweeping of the dislocation segments, formation of screw dipoles and edge dislocations breaking away from the dislocation loop. Higher temperatures promote the absorption of dislocation loops and reduce the CRSS. The length of a [010] dislocation segment swept by a 1/2[111] edge dislocation increases with increasing dislocation loop radius which increases the CRSS.

The nanotube synthesis process greatly influences the microstructure and photocatalytic characteristics of titania (TiO₂) nanotubes. Most studies have synthesized nanotubes using anatase crystals or mixtures of anatase and rutile crystals. This study investigated the effect of the precursor on the formation of TiO₂ nanotubes and on their photocatalytic properties by using hydrothermal synthesis of TiO₂ nanotubes using amorphous titanium hydroxide (Ti(OH)₄) as the titanium source. This study then analyzed the phase evolution and the morphology of the hydrothermal synthesized products and characterized the physical and chemical properties of the TiO₂ nanotubes. The results show that the optimal temperature for the hydrothermal synthesis is 150 ℃ for 16 h. The hydrothermal product was first washed with water, then acid, and then with water again. The product was then calcined at 400 ℃ for 2 h to produce anatase nanotubes with good crystallinity. The hydrothermal reaction induced the amorphous Ti(OH)₄ to transform into thin-flake sodium titanate (Na₂Ti₃O₇). Then, the Na₂Ti₃O₇ was transformed to titanate (H₂Ti₄O₉) nanotubes induced by washing with water and acid. Finally, the calcination promoted conversion of the H₂Ti₄O₉ nanotubes to anatase nanotubes. The greatest photocatalytic degradation occurred when the nanotubes were calcined at 400 ℃ for 2 h.

New particle formation (NPF) events are a key source of atmospheric aerosols which then profoundly influence the global climate, regional environmental quality and even human health. With the continuous development of both new particle and precursor monitoring instruments in the past few years, the literature has various field observations of NPF events in various atmospheric environments. In particular, NPF has occasionally been observed in polluted atmospheres in recent years, so the mechanism of new particles nucleation and growth in high concentration condensation sinks (CS) have gradually become much interest. This paper summarizes recent studies of NPF events in polluted areas in China and worldwide which emphasize the occurrence and development characteristics and factors inducing NPF events. This review also describes the formation mechanisms and the key chemical components contributing to growth, the climate effect and environmental impact, and the future research directions of the NPF events in polluted atmospheres based on the current research.

Syntax-first models and semantic priority are two opposing views in sentence processing theory. This study took N400 and P600 effects as the main analysis objects to explore the cognitive processing mechanism of Chinese sentences with semantic violations, with syntax violations and with both semantic and syntax violations of the "subject (noun) + predicate (verb) + object (noun)" structure without modifiers (referred to as Chinese [S+V+O] simple sentence structure) in the brain. The results of figures showed that semantic violation sentences, syntactic violation sentences, and combined violation sentences all triggered the N400 effect between 300 and 400 ms. Among them, the N400 amplitude of the semantic violation sentence and the syntactic violation sentence were similar, but the N400 amplitude for sentences with both semantic and syntax violations were more negative than the N400 amplitude with only one semantic and sytax violation. Only the semantical violations produced the P600 tendency. The research results indicated that Chinese sentences with the [S+V+O] simple structure might not fit with syntax-first model. The results also showed that the brain response to this sentence structure differs from the EEG amplitude caused by the "ba" sentence and the "bei" sentence. Thus, this research concludes that sentence processing in brain might differ for language types and language structures.