Search Results (15)

Since large-flow water diversion began in the middle route of the South-to-North Water Diversion Project, inverted siphons have experienced varying degrees of local flow pattern disorder at their inlets and outlets, resulting in a significant decline in hydraulic performance. Taking the Kuhe inverted siphon as a case study, a combination of numerical simulation and on-site testing was used to explore the causes of flow pattern disorder at the outlet of the inverted siphon. Meanwhile, based on the actual engineering situation, the influence of the flow pattern optimization measure of installing a 5D (five times the diameter of the pier) diversion pier at the outlet of the inverted siphon on its hydraulic characteristics was studied. Research findings indicated that before the implementation of flow pattern optimization measures, the Karman vortex street phenomenon was found to occur when water flowed through the piers; the interaction of the vortex streets behind each pier led to flow pattern disorder and affected the flow capacity. After implementation of the flow pattern optimization measures, the diversion piers had a significant inhibitory effect on the formation and development of the Karman vortex street behind the piers under the dispatching and design flow conditions. The flow velocities in each vertical layer were adjusted, with a significant improvement in the flow pattern. The hydraulic loss of the Kuhe inverted siphon was reduced by 11.5 mm, or approximately 7.8%. Under the dispatching flow condition, the water diversion flow of the Kuhe inverted siphon increased by approximately 4.11%. The water diversion capacity of the structure could be effectively enhanced by adding diversion piers to the tails of the piers. This method can be widely applied in similar open-channel long-distance water diversion projects. Full article

As a long lifeline system of buried structures, the utility tunnel (UT) is vulnerable to earthquake invasion. For utility tunnels with inverted siphon arrangements crossing rivers, the seismic response is more complex due to the basin effect of acceleration in the topography and the influence of fluctuating hydrodynamic pressure, but there is currently a gap in targeted seismic response analyses and references. Based on a UT project in Haikou, this paper studied seismic responses of a cast-in-place UT considering the coupled model of water–soil–tunnel structure on ABAQUS software. Herein, the dynamic fluctuation of hydrodynamic pressure is simulated using an acoustic–solid interaction model. A viscoelastic artificial boundary was used to simulate the soil boundary effect, and seismic loads were equivalent to nodal forces. Considering seismic invading direction and varying water elevation, this paper investigates the dynamic response characteristics and damage mechanisms of river-crossing utility tunnels. This study shows that the basin effect causes the soil acceleration around the UT to show variability in different sections, and the amplification factor of the peak acceleration at the central location is almost doubled. The damage and dynamic water pressure of the UT are intensified under bidirectional seismic excitation, and the damage location is concentrated at the junction of the horizontal section and the vertical section. Bending moments and axial forces are the main mechanical behaviors along the axial direction. Changes in river levels have a certain positive effect on the UT peak MISES, DAMAGEC, and SDEG, and it exhibits a certain degree of energy dissipation and seismic damping effect. For the aseismic design of cross-river cast-in-place utility tunnels, bidirectional seismic calculations should be performed, and the influence of river hydrodynamic pressure should not be neglected. Full article

Not long after the Colonia Copia Felix Munatia Lugdunum, in present day Lyon, France, was founded in 43 BCE by Lucius Munantius Plancus on the 300 m high Fourvière hill overlooking the Saone and Rhône rivers and the plains to the north and east, it became the capital of the Gallia provinces, growing to be with some 50,000 inhabitants the largest town in Gaul. In the early days, the colonia on the west valleys surrounded Fourvière hill and depended on local springs, wells, and rain cisterns for its water provision, which soon became insufficient for the growing city. A first aqueduct was constructed in 20 BCE, bringing waters from a spring some 10 km north of the town. In the decades to follow, another three aqueducts were added. All of the aqueducts were equipped with one or more pressure lines and installations of (inverted) siphons, totaling nine, to cross valleys that were thought too deep or too wide for a bridge. Today, the Métropole de Lyon counts over a million inhabitants; it is after Paris and Marseille the third largest town in France. Since 1998, Lyon has been listed on the UNESCO World Heritage List, among others, because of the historic architecture in its urban settlements over 2000 years of age. This manuscript recounts the history and present remains of the four aqueducts and their nine extraordinary siphons, and is dedicated to Dr. Jean Burdy, who, with his team over many years of research of earlier literature and of investigations and discoveries of the physical remains of valley sites, produced a great number of publications saving the Lyon aqueducts from oblivion and leading to restorations in recent times. Full article

High-quality economic development is an inevitable requirement for promoting sustainable development. Stacks of research papers have suggested that the quality of China’s economic development will make an important contribution to promoting global sustainable development. The collaborative agglomeration between manufacturing and producer services is determined by multiple factors, including industrial characteristics and industrial associations. This is conducive to the efficient evolution of the industrial structure and to further achieving high-quality economic development. Based on the provincial data from 2010 to 2021 in China, this research evaluated the impact of co-agglomeration between manufacturing and producer services on high-quality economic development by using the double-fixed-effect spatial Durbin model. The benchmark regression results showed that industrial co-agglomeration impacted high-quality economic development in an inverted U-shaped. This result had a significant positive spatial spillover and was robust. In the spatial heterogeneity tests, the co-agglomeration of industries had different effects on high-quality development in regions. The strongest spillover effect of positive externalities was in the eastern region, which played an active role as a “growth pole”. The “siphon effect” happened in the central region. The spillover effect had a “U” shape in the western region, and the co-agglomeration inhibited current high-quality development. In the mechanism analysis, the industrial co-agglomeration enhanced high-quality development by stimulating green innovation, and the digital economy had a positive moderating effect. The study presented in this article provides empirical evidence and offers policy recommendations for formulating industrial policies and improving the quality of economic development. Full article

This study focuses on optimizing the foundation pit dewatering scheme using the foundation pit dewatering theory and the principles of multi-objective optimization. It explores the development of a multi-objective optimization model and efficient solution technology for foundation pit dewatering. This research focuses on the foundation pit dewatering project at the inverted siphon section of Xixiayuan canal head, specifically from pile number XZ0+326 to XZ0+500. It establishes an optimized mathematical model for foundation pit dewatering that incorporates three objectives. Additionally, a dewatering optimization program is developed by utilizing the MATLAB optimization toolbox and the multi-objective optimization algorithm program based on the NSGA-II algorithm (Gamultiobj). The multi-objective optimization mathematical model is solved, and a Pareto-optimal solution set with uniform distribution is obtained. The multi-objective optimization evaluation system based on AHP is constructed from the three aspects of dewatering cost, the impact of settlement on the environment, and the safety and stability of the foundation pit. The optimization scheme of the Pareto-optimal solution set is selected as the decision result to provide multiple feasible schemes for the dewatering construction of foundation pits. The optimization scheme is verified by using the GMS software. The simulation results demonstrate that the optimization scheme fulfills the requirements for water level and settlement control. Moreover, the developed optimization program efficiently solves the multi-objective optimization problem associated with foundation pit dewatering. Lastly, an evaluation system incorporating the NSGA-II algorithm and AHP is developed and utilized in the context of dewatering engineering in order to offer multiple viable optimal dewatering schemes. Full article

The main canal of the middle route of the South-to-North Water Diversion Project has the risk of excess head loss in crossing water-conveyance structures, but the assessment of this risk faces difficulties such as the lack of sufficient monitoring points inside the structures, the current water-conveyance flow rate being lower than the design maximum flow rate, and the lack of verification of monitoring data. Monitoring data of the main canal were collected in 2022, prototype observations were carried out, the monitoring data were verified, and a method for calculating the head loss using the combined head loss coefficient was proposed. The assessment of 143 structures showed that 40 structures had excess head losses, including 31 inverted siphons, four aqueducts, four underdrains, and one culvert. The 143 structures had a total residual head of 3.05 m, accounting for 9% of the distributed head. In addition to natural aging, freshwater mussel and algal attachment, sediments, and undesirable flow regimes were all important influencing factors that caused the head loss to increase. It is recommended to take measures such as regular removal of sediments and algae and freshwater mussel attachments, optimization of inlet and outlet shapes, and application of roughness-reducing materials. Full article

Agriculture is the national economy’s primary industry, and its carbon emissions (CE) are one of the most significant factors influencing the environment. As a large agrarian province, reducing the carbon emission intensity (CEI) of agricultural is of great practical significance to the sustainable development of agriculture in Henan province. In this paper, the CEI of rice, maize, and wheat from 2001 to 2020 in 18 prefecture-level cities in Henan province was calculated, and its spatial-temporal evolution patterns were analyzed. The Spatial Dubin model was used to study the impact mechanism and spatial spillover effect of the main crops’ CEI. As a result, the following was determined: (1) The CEI of main crops in 18 cities of Henan province showed an inverted “V” shape, whereas the geographical distribution showed an oblique “T” shape mainly in the north and west. (2) The CEI of main crops was significantly different under different factors. Technical efficiency, agricultural openness, urbanization level, agriculture production agglomeration, and agriculture fiscal expenditure negatively impact the main crops’ CEI. The structure of the food industry and the cost of water for agriculture and forestry positively affect the CEI of main crops. (3) The spatial spillover effects of agricultural openness, production technology efficiency, environmental protection, and fiscal expenditure spread to the surrounding areas through factor flow, technology spillover, and policy spread. The efficiency of production technology and fiscal expenditure on environmental protection have a demonstrative effect, and the degree of agricultural openness has a siphon effect. Based on the research results, we should strengthen agriculture technology extension and investment and gradually improve technical efficiency. Agriculture should be financially supported by the government. We will actively promote the optimization of the structure of the grain industry by promoting orderly urbanization, strengthening the sharing of factors among regions, and reducing the CEI of main crops. Full article

This paper studies Karman vortex shedding and water-level fluctuation in the inverted siphon structure of the Middle Route of the South-to-North Water Diversion Project (MR-SNWDP) in China. Field investigations and numerical simulations for the inverted siphon outlet were performed to explore the characteristics and hazards of the vortex. Numerical results were compared with measured data to verify the effectiveness and reliability of the model. Based on the model, it is found that the periodic water-level fluctuations caused by the Karman vortex street will not only excite surges to beat the gate but will also induce periodical force on the gate pier. Those will damage the building structure and affect the delivery capacity in the long-term operation. Based on this, countermeasures of altering different pier tail shapes are proposed to control vortex shedding, and the effect is noticeable. The study presents a hydraulic process for the inverted siphon outlet and provides a theoretical reference for water delivery safety of inverted siphons and similar structures in MR-SNWDP. Full article

As regional interaction increases in an open economy, a region’s green total factor productivity in agriculture must be considered alongside relationships with other regions. In this study, the slack-based model (SBM) global Malmquist–Luenberger (GML) index is used to measure the green total factor productivity of agriculture in each province of China, and the social network analysis (SNA) and vector autoregressive model (VAR) impulse response function (IRF) are used to examine the spatial network structure and regional interactivity. The research confirms that the absolute value and concentration of agricultural green total factor productivity are generally higher in the south than in the north of China, but the peak is lower in the south than in the north. The network density of agricultural green total factor productivity in China from 2008 to 2019 shows an increase, with the cut-off values of mean, 10, 50, and 100 treated as 4.97%, 2.57%, 3.30%, and 2.43%, respectively. From 2008 to 2019, the central potentials of network entry and network exit of green total factor productivity in China’s agriculture show a “V”-shaped and inverted “V”-shaped evolution path, respectively, with the density of cohesive subgroups growing, which demonstrates that the spatial structure of green total factor productivity in Chinese agriculture has experienced an evolutionary path from polycentric to monocentric to polycentric conditions. The spatial interaction of different cohesive subgroups is intensifying and has a certain degree of self-stability. In terms of regional interaction, the siphon effect of the east on the green development of agriculture in the central and western regions is significant, but the trickle-down effect is not obvious, and the interaction between the central and western regions has a catalytic effect on the efficiency of the green economy of agriculture in both regions. It is recommended that targeted policies be introduced to support the flow of agricultural factors and industrial division of labour between the central and western regions and the south and north, taking into account the actual situation. The novelty of this paper is that it focuses on the green total factor productivity of Chinese agriculture and combines the innovative use of the social network analysis paradigm to analyse the green development of agriculture in a country from a spatial dynamic evolutionary perspective. A limitation of the research methodology in this paper is its poor applicability to closed economy analysis. Full article

Analyzing the impact of agricultural industrial agglomeration (AIG) on agricultural green development (AGD) is of a great significance to realizing the sustainable and high-quality development of agriculture. Panel data of 31 provinces in China from 2009 to 2019 were analysed. For measuring efficiency, a non-parametric DEA approach in the presence of undesirable outputs, a slack-based measure (SBM) was used. From the perspective of the spatial spillover analysis and heterogeneity analysis, Moran’s I index and the Spatial Durbin Model (SDM) were used to empirically analyze the impact of AIG on AGD to alleviate conflicts between agricultural sustainable development and environmental pollution and further explore the regional heterogeneity of AIG on AGD-efficiency due to the vast territory of China. The mediation model is constructed to explore the paths of AIG affecting AGD. The results show that: (1) Chinese efficiency of AGD was raised continuously and the high efficiency was mainly located in the southeastern coastal areas. (2) AIG not only has a significant U-shaped impact on the AGD, but also has a nonlinear U-shaped spatial spillover effect in related regions, which shows that the “siphon effect” will be triggered in the early stage of AIG and the “diffusion effect” will be evoked in the later stage of AIG. (3) From the perspective of heterogeneity analysis, AIG significantly promotes the efficiency of AGD in the central region of mainland China. In the eastern region, the AIG has an inverted U-shaped effect on the efficiency of AGD from positive to negative. On the contrary, the AIG has a U-shaped impact on the efficiency of AGD from negative to positive in the western region. (4) The analysis of the mediation model plays a partial positive mediating role for AGD to persist in promoting technology innovation and increasing the speed of talent agglomeration. Accordingly, suggestions are provided to strengthen the coordination and cooperation in sustainable agricultural development among provinces, to drive the efficiency of science and technology through the scale knowledge spillover effect, and to conduct a scientific layout of agricultural industry development. Full article

In Roman times long distance water transport was realized by means of aqueducts. Water was conveyed in mortared open channels with a downward slope from spring to destination. Also wooden channels and clay pipelines were applied. The Aqua Appia, the oldest aqueduct of Rome, was constructed in the third Century BCE. During the Pax Romana (second Century CE), a time of little political turmoil, prosperity greatly increased, almost every town acquiring one or more aqueducts to meet the rising demand from the growth of population, the increasing number of public and private bath buildings, and the higher luxury level in general. Until today over 1600 aqueducts have been described, Gallia (France) alone counting more than 300. Whenever a valley was judged to be too wide or too deep to be crossed by a bridge, pressure lines known as ‘inverted siphons’ or simply ‘siphons’ were employed. These closed conduits transported water across a valley according the principle of communicating vessels. About 80 classical siphons are presently known with one out of twenty aqueducts being equipped with a siphon. After an introductory note about aqueducts in general, this report treats the ancient pressure conduit systems with the technical problems encountered in design and function, the techniques that the ancient engineers applied to cope with these problems, and the texts of the Roman author Vitruvius on the subject. Reviewers noted that the report is rather long, and it is. Yet to understand the difficulties that the engineers of those days encountered in view of the materials available for their siphons (stone, ceramics, lead), many a hydraulic aspect will be discussed. Aspects that for the modern hydraulic engineer may be common knowledge and of minor importance when constructing pressure lines, in view of modern construction materials. It was different in Vitruvius’s days. Full article

An experimental and numerical study is presented in the current work for gas entrainment using an inverted vertical U-tube. Water flows vertically up in an inverted U-tube which creates a low-pressure region in the tube upper portion. This low-pressure region can be used to extract gases by connecting it to a branch pipe. The extracted gases considered in this work are a mixture of air and water vapor. The water vapor from the side branch pipe is mixed with the flowing water under the siphon effect. This results in a progressive water vapor condensation as the mixture proceeds towards the exit due to an increase in vapor partial pressure. The air is drawn by inertia to be released out at the tube lower exit of the inverted U-pipe. The current study deals with these complicated flow behaviors due to the mixing undergoing condensation. A test rig is designed for experimentally studying the behavior of water flow in an inverted U-tube where the air is mixed with the flowing water at the top region of this tube. The CFD computations are accomplished for a side gas mixture with volume fractions up to 0.7 with water vapor mass fractions in this mixture to be 0.1–0.5. The tested water mass flow rates in the main tube are 2, 4, 6, 8 kg/s to account for all possible flow mass ratios. The CFD computations are validated with water and air two phase flow with the measurements of both the experiments of the current research and the literature. The present results reveal that slightly raising the water mass flow rate at a constant side mixture mass ratio produces a reduced generated pressure in the upper tube part. This is attributed to extra water vapor condensation taking place rapidly by increasing the water flow rate in the tube upper part. Furthermore, the turbulence quantities begin to break down at a side mixture volume fraction of 0.55 with water and air mass flow rates of 2 kg/s and 0.002 kg/s, respectively. On the other side, raising the air mass flow rate at the higher values of water vapor and water mass flow rates breaks the generated vacuum pressure and turbulence due to entrainment. Moreover, this proposed framework can produce a lower static pressure, reaching 55.1 kPa, which makes it attractive for gas extraction. This new technique presents innovative usage with less consumable energy for extracting gases in engineering equipment. Full article

An underground aqueduct is usually a canal built in the subsurface to transfer water from a starting point to a distant location. Systems of underground aqueducts have been applied by ancient civilizations to manage different aspects of water supply. This research reviews underground aqueducts from the prehistoric period to modern times to assess the potential of achieving sustainable development of water distribution in the sectors of agriculture and urban management, and provides valuable insights into various types of ancient underground systems and tunnels. The review illustrates how these old structures are a testament of ancient people’s ability to manage water resources using sustainable tools such as aqueducts, where the functionality works by using, besides gravity, only “natural” engineering tools like inverted siphons. The study sheds new light on human’s capability to collect and use water in the past. In addition, it critically analyzes numerous examples of ancient/historic/pre-industrial underground water supply systems that appear to have remained sustainable up until recent times. The sustainability of several underground structures is examined, correlated to their sound construction and regular maintenance. Moreover, several lessons can be learned from the analysis of ancient hydraulic works, particularly now, as many periodically hydrologic crises have occurred recently, overwhelmingly impacted by climate change and/or over-exploitation and degradation of available water resources. Full article

The emergency control of Menglou~Qifang inverted siphon, which is about 72 km long, is the key to the safety of the Northern Hubei Water Transfer Project. Given the complicated layout of this project, traditional emergency control method has been challenged with the fast hydraulic transient characteristics of pressurized flow. This paper describes the application of model predictive control (MPC), a popular automatic control algorithm advanced in explicitly accounting for various constraints and optimizing control operation, in emergency condition. For the fast prediction to the pipe-canal combination system, a linear model for large-scale inverted siphon proposed by the latest research and the integrator-delay (ID) model for open canals are used. Simulation results show that the proposed MPC algorithm has promising performance on guaranteeing the safety of the project when there are sudden flow obstruction incidents of varying degrees downstream. Compared with control groups, the peak pressure can be reduced by 17.2 m by MPC under the most critical scenario, albeit with more complicated gates operations and more water release (up to 9.75 × 10⁴ m³). Based on the linear model for long inverted siphon, this work highlights the applicability of MPC in the emergency control of large-scale pipe-canal combination system. Full article

Long distance water diversion projects are developed to alleviate the conflicts between supply and demand of water resources across different watersheds. However, the significant scale water diversion projects bring new challenges for the water supply security. This paper presents the flood risk of inverted siphon structure which is used for crossing transversally in the water diversion project through sensitivity analysis. Soboĺ and regionalized sensitivity analysis are used to investigate the sensitive parameters of the integrated model and the sensitive range of the parameters, respectively. The integrated system model consists of the hydrologic model, the sediment transport model and the siphon hydraulic model to determine the flood overtopping duration and volume, which are used to quantify flood risk in this study. The flood overtopping duration and volume indicators are used to quantify flood risk in the sensitivity analysis. The South to North Water Diversion Project in China is used as a case study. The results show the mean rainfall and roughness coefficient of the pipe are the most sensitive parameters in the integrated models, while the sensitive range of these two parameters are distinct. The sensitivity analysis of the inverted siphon provides an insight into the significant contributions to the flood risk. The analysis can provide the guidance for the system operation security. Full article