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Rapid flow-like landslides frequently occur in mountainous regions. To mitigate the disasters caused by these landslides, it is crucial to develop robust numerical models that can accurately predict their run-out processes. Models based on the material point method (MPM) offer significant advantages in simulating large deformation issues in geomaterials, including landslides. However, applying these models to accurately simulate real-world rapid flow-like landslides remains a challenge, primarily due to the complexities involved in handling the three-dimensional (3D) sliding bed boundary. This paper introduces a novel 3D MPM model specifically designed for simulating rapid flow-like landslides that propagate across curved beds. The constraints of the sliding bed on the landslide are imposed by the boundary nodes close to the bed. These boundary nodes carry information about the normal vector of the sliding bed, derived directly from the digital terrain model (DTM). Furthermore, the model integrates a hybrid formulation that combines the Full Lagrangian Implicit Particle (FLIP) method with the Particle In Cell (PIC) method, facilitating a stable solution for the velocity and position of material points. The effectiveness of the proposed model is confirmed through a numerical analysis of a rigid block sliding down an inclined plane and an experiment of sand flow on a curved bed. The simulation results from these two benchmark scenarios align closely with both analytical and experimental data, attesting to the validity of the model. The model is then applied to analyze a rapid flow-like landslide that occurred in Gansu Province, China, characterized by a curved sliding bed. The outcomes illustrate the model's capability to efficiently capture the landslide's climbing and turning motions induced by the meandering topography. Moreover, it successfully reproduces the main deposition characteristics observed in the field, demonstrating the model's strong suitability for simulating the propagation of rapid flow-like landslides on naturally curved beds. [ABSTRACT FROM AUTHOR]

• The influences of the geometric parameters of the reactor on the SCPP-HPCR are investigated. • A formula is proposed to calculate the CO 2 emissions reduction of the system. • The optimal operating conditions of the SCPP-HPCR is analyzed. • 2.38 kg of CH 4 is degraded and 375.52 kg of CO 2 is reduced through the system one day. The increase of 1.09 °C in global temperature resulted in significant catastrophes because of the extreme climate. The climate change rate can be slowed down by reducing the levels of CH 4 and CO 2 in the atmosphere. The solar chimney power plant integrated with a honeycomb photocatalytic reactor (SCPP-HPCR) uses the photocatalytic technology to remove atmospheric CH 4. In addition, CO 2 emissions can be reduced from coal fired power plant due to the generating capacity of the system. In this paper, the influence of the geometric parameters of the reactor and turbine on the overall performance of the SCPP-HPCR is studied by numerical simulation. The obtained results showed that the flow resistance inside the system was mostly caused by the HPCR at low turbine speed, and primarily by the turbine at high turbine speed. Reducing the pore diameter of the reactor could improve the photocatalytic performance of the SCPP-HPCR more than increasing the turbine speed. The SCPP-HPCR having a pore diameter of 3 mm, porosity of 0.85, and constant turbine speed of 180 rpm, built in Qianyanzhou, China, could remove 2.38 kg of CH 4 and reduce 375.52 kg of CO 2 in one day. [ABSTRACT FROM AUTHOR]

High-speed railways often run over underground metro stations. Dynamic load induced by high-speed train can influence the internal force of underground structure and hence can pose danger to the underground structure. Hence, it is necessary to estimate the safety of underground structure due to high-speed train load. In this paper, the effects of dynamic load induced by high-speed train on metro station are investigated by carrying out three-dimensional numerical analysis. Guinan high-speed railway, which is designed to run over Jinqiao metro station in Nanning, Guangxi province of China are adopted as the background of this case study. The hardening soil model with small-strain stiffness was adopted to model the behaviour of soil. Two typical speed of railway train (i.e., 160 km/h and 350 km/h) are considered in this study. Based on the numerical analysis, vertical vibration acceleration and bending moment of the structure of the metro station are presented and analysed. [ABSTRACT FROM AUTHOR]

Objectives: For the traditional conformal conic projection, Newton 's iterative method is generally used to solve the reference latitude. However, the method requires to be iterated repeatedly, which leads to relatively low computational efficiency and is not easy to be extended and utilized. Therefore, non-iterative expressions for the reference latitudes B0，B1，B2 of the spherical conformal conic projection are derived in this paper to facilitate theoretical analysis and numerical computation. Methods: In order to simplify the fussy iterative algorithm in calculating the reference latitude of the traditional conformal conic projection, the average latitude and the average latitude difference were introduced. With the help of the powerful computer algebra system Mathematica, the non-iterative algorithm of the conformal conic projection based on the sphere model is proposed. Compared with the traditional ellipsoid iterative algorithm, the country and provinces with different latitude differences are taken as examples. Results: Numerical examples show that the maximum relative error of the reference latitudes B0，B1，B2 calculated by the non-iterative formula of the sphere model derived is less than 2.011% and the relative error of length deformation is less than 1 × 10-6. For provinces with different latitude differences, the smaller the latitude difference, the closer the reference latitude calculated based on the sphere model to that based on the ellipsoid model, the smaller the relative error of length, and the closer the length deformation. Conclusions: The derived non-iterative expressions overcome the tedious iterative process and make the theoretical analysis more convenient, which enriches the map projection theory to a certain extent. The established mathematical model can be extended to the non-iterative algorithm for solving the reference latitude for rectifying and authalic conic projection under the sphere model and each conic projection under the ellipsoidal model, and the algorithm is applicable to the whole map of China and all provinces. Therefore, the non-iterative algorithm of spherical conic projection derived can be used to replace the traditional complex iterative algorithm in the process of making small and medium scale maps in China. [ABSTRACT FROM AUTHOR]

2E12 is a new aluminum alloy material made in China. It is to be used in aircraft fuselage skin structure. Damage tolerance performance is one of its key indicators for the material. According to the requirement of damage tolerance design, this paper designs three typical test pieces of fuselage panel structure, including single-span crack, double-span crack and crack repair. Firstly, the numerical analysis of crack propagation and residual strength is completed, and then the verification test is carried out. The results are compared with those of 2024 aluminum alloy. The results show that the damage tolerance of 2E12 aluminum alloy material can meet the design requirements. Compared with single crack propagation, the existence of multi-crack increases the crack growth rate significantly, and the total life of multi-cracks is shortened by about 30%. The error of crack propagation analysis and test results is less than 10%. The residual strengths of all test pieces are in good agreement, and the difference between the analytical results and the experimental results is about 2.3%. [ABSTRACT FROM AUTHOR]

The development of underground space is fast because of the lack of space. To build shafts in underwater tunnels, the vertical tunneling method (VTM) was invented in 1974 in China, which can act as a freshwater intake or sewage outlet. During the operation of the VTM, the jacking force is one of the essential factors that draw attention. This paper conducts a numerical study of the jacking force and its influencing factors during the vertical tunneling process. First, based on the finite element software ABAQUS, a numerical model of the vertical tunneling process is established according to the VTM project in Beihai, China. Second, in accordance with the Latin hypercube sampling method and the multivariate significance analysis, the mechanical parameters are determined or back-analyzed. Then, the calculated jacking force of the numerical model is compared with the measured jacking force. It turns out that the changing trend of the jacking force in the numerical model and the measured jacking force is relatively consistent. Finally, the influencing factors of the jacking force, such as elastic modulus and the angle of internal friction, are analyzed based on the numerical model. The results show that the elastic modulus and the angle of internal friction of soil are the main influencing factors of the jacking force. The secondary factors are Poisson's ratio, static earth pressure coefficient, unit weight, and cohesion. [ABSTRACT FROM AUTHOR]

The talus-like rock mass is a special kind of geomaterial widely distributed in southwestern China, which has induced serious engineering disasters for tunneling engineering. However, the mechanical behavior of the talus-like rock mass remains unclear as the previous studies mainly focused on similar geomaterials such as the soil–rock mixtures. In this paper, we have carried out both experimental and discrete element method (DEM)-based numerical analyses to investigate the shearing characteristics of the talus-like rock mass collected from a real project site. Large-scale direct shear tests reveal that the strength parameters increase with the block content, which is different from the traditional soil–rock mixture. A dependence has been discovered in that the specimen dilation becomes more obvious under lower normal stress and larger block content. It is also observed that higher normal stress is beneficial for crushing blocks. The force chains obtained in the DEM simulations show that distinct internal structures are generated in the rock samples with different block contents. The distribution of coordination number establishes the dependence of fabric stability on block content during shearing. Bond-break evolution reveals the tendencies of crushed particles were consistent with those of experimental tests. The findings provide a more in-depth understanding about the mechanical behavior of the talus-like rock mass, which helps to uncover the cause of the collapse of the real tunnel project. [ABSTRACT FROM AUTHOR]

On 5 April 2021, a high-position landslide occurred in Tiejiangwan, Liujiang Town of Hongya County, Sichuan Province, China. The detached mass transformed into a debris avalanche traveled about 1300 m with an elevation difference of 665 m and caused three fatalities. Then landslide deposits were initiated by continuous rainfall and evolved to a debris flow five days later, forming a secondary disaster chain. The rapid characterization of a landslide-debris flow chain (LDC) is a critical step in remediation works and future early warning of failure. This paper proposes a rapid disaster information integration and assessment method for providing information on LDC occurrence, failure mechanisms, and potential hazard-affected areas via examining and characterizing the Tiejiangwan LDC based on multi-method including geomorphological mapping, structural characterization, kinematic analysis and numerical simulation. The results suggested that the first landslide initiated from a mountain ridge that experienced historical deformation extended over the fractured argillaceous siltstones. Constrained by three discontinuity sets, the failure mode was determined as planar failure along a sub-vertical defect. The cause of first landslide can be attributed to a jointed effect of structural plane, tectonic activity, terrain and slope structure, while rainfall is the dominating triggering factor. Deposits with loose structure subjected to persistent rainfall and gully topography contribute to the occurrence of secondary debris flow. Using UAV and LiDAR identification, the unstable elements in the surrounding cliffs of the source area are derived and a three-dimensional simulation was implemented to detect the energy, velocity, height and reach of detached blocks. The proposed method leads to rapid characterization of LDC and assists the evaluation of cliff instability of these environments. Highlights: We proposed a rapid and integrated assessment system for landslide-debris flow chain occurrence, failure mechanisms, and potential hazard-affected areas identification. Quantitative study was conducted on the evolution from landslide deposits to debris flow. 3D simulation was performed to reveal the runout behaviors of surrounding potential dangerous rockfall areas. [ABSTRACT FROM AUTHOR]

This paper first proposes a European option pricing method for deposit insurance based on triangular intuitionistic fuzzy numbers. In the proposed method, we take into account the randomness and fuzziness of bank asset value simultaneously, and hence, the method can adequately reflect the high uncertainty of bank asset value. This method fuzzifies the value of bank asset, resubmits it into the original deposit insurance option pricing model as a fuzzy random variable, and then gives an analytic formula of deposit insurance rates using a risk-neutral method. After this, we have also conducted a numerical analysis. In specific, we have obtained the premium interval and presented the static analysis of key parameters. Finally, seven small- and middle-sized banks in Hunan Province in China are used as examples to validate the proposed interval pricing model. The Black-Scholes option pricing model and Yoshida's triangular fuzzy model are also employed for comparison. The research results show that the interval rates obtained from the proposed European option pricing method for deposit insurance can better reflect the uncertainty of bank asset evaluation than the fixed rates obtained from the Black-Scholes option pricing model. Moreover, the model proposed in this paper is also superior to Yoshida's model in practice. [ABSTRACT FROM AUTHOR]

With the rapid development of agriculture in China today, the demand for agricultural machinery is rapidly increasing. A large amount of exhaust gas emissions poses a severe threat to the environment. To better promote engine fuel and air mixing, enhance engine performance, and achieve low emissions, we conducted a numerical study of the pre-chamber and nozzle design in a gasoline engine for an agricultural tractor by using the G-equation method in Converge CFD software. The relevant optimization of the three model parameters in the G-equation was performed using the improved particle swarm algorithm (PSO). The model parameters after optimization by the PSO algorithm were: a 1 = 0.77 , b 1 = 2.0 , b 3 = 1.0 . It was confirmed that the predicted engine performance was enhanced greatly with the pre-chamber system. More importantly, the results reveal that the volume and area ratios of the pre-chamber played a crucial role in the performance of the pre-chamber. Through a series of parametric studies on the pre-chamber and main chamber characteristics, we can identify the best sets of volume and area ratios based on the combustion reaction progress, the turbulent mixing profiles, and the exhaust gas emission. The turbulent maximum strength and the exhaust gas concentration of nitrogen oxides can differ by 13 and 18 times, respectively. In practical design, we recommend the optimization of the concerned metrics with the findings in the paper. [ABSTRACT FROM AUTHOR]

This paper developed a quantitative evaluation necessary to ensure ground stability, so a quantitative indicator (bearing capacity). A homogeneous axisymmetric model was generated, considering China's stress field and the Karst topography characteristics, simultaneously obtaining stress component expression. We then determined the bearing capacity calculation formula by combining the strength theory of shear failure and the stress component expressions. Finally, the comparison of the bearing capacity calculation results between theoretical analysis and a numerical simulation indicated that the error was less than 5%, and the result verified the rationality of the formula. [ABSTRACT FROM AUTHOR]

Based on field geological survey and unmanned aerial vehicle (UAV) photography, this paper studied the inherent causes, intrinsic mechanisms, and kinematic characteristics of a catastrophic landslide of dissolved and fractured rock slope in a mountainous area of Southwestern China. The discrete element method (DEM) model of representative volume element of fractured rock mass considering karst existence was developed with its micromechanical parameters calibrated from laboratory element tests. The coupled finite difference and discrete element methods (FDM-DEM) were then employed to simulate deformation and failure evolution and collapse development of the rock slope with both internal and externally triggering factors properly addressed. The kinematic characteristics of mobile collapse debris flow were analyzed, and the numerical simulation results were validated by laboratory physical model test. The results show that the internal causes were mainly manifested in slope structure, lithology combination, karst, and fracture development, among which the unfavorable interaction disintegrated rock masses. The primary external cause was the staged underground coal-mining operations underneath the collapsed body, which led to large cracks appearing at the back edges of the slope. The maximum velocity of mobile collapse debris was about 65 m/s with the maximum travel distance of more than 600 m. Numerical simulation results matched well with both field forensic investigation and laboratory physical model test results. The findings would help further understand the deformation and failure process of fractured rock slope subject to underground mining and provide technical reference for accurate assessment and proper mitigation of similar landslide disasters. [ABSTRACT FROM AUTHOR]

This paper takes Fen-Wei Basin (FWB) as a case to study the ground fissures controlled by normal fault. Based on the field investigation, geophysical exploration, drilling, GNSS data and numerical calculation, the characteristics and mechanism of ground fissures originated from the hanging wall of normal faults are revealed. The results show that the distribution of ground fissures in the hanging wall and heading wall of the active faults is not uniform. Ground fissures are mostly distributed in the hanging wall of active faults and show a linear distribution on the surface, their strike is consistent with the fault, mainly characterized by vertical offset and horizontal tension. Ground fissures destroy the farmland and building foundation through which they pass and cause the rupture or displacement. In profile section, the ground fissure shows the characteristics of normal faults and dislocates the strata, and is connected with the underlying faults. Numerical analysis shows that the vertical displacement of normal fault activity in hanging wall is much larger than that in heading wall, which is the reason that tectonic ground fissures mainly originate from hanging wall. The range of dangerous area of ground fissures is controlled by the depth of fault, the strength of the ground fissures disaster is mainly controlled by the activity of fault. The formation of the ground fissures originated from the hanging wall of the fault experienced three stages: the main fault activity stage, the secondary fault activity stage and the fissure formation stage. [ABSTRACT FROM AUTHOR]

[Display omitted] • A CEL model of the vertical tunneling process is established. • The failure mechanism of vertical tunneling is categorized into four phases. • The failure zone changes from a small conical frustum to a large one. • The changing trend of the top diameter of the inverse conical frustum is revealed. • An empirical shear failure method to predict the jacking force is proposed. Over the past few decades, a significant surge has occurred in the domain of underground space construction and development, especially in China. The vertical tunneling method has gained popularity among emerging methods for building water inlets and sewage outlets in horizontal tunnels. While this method has been previously studied, a significant knowledge gap persists concerning the failure mechanism above the standpipe. To address this issue, in this paper, the Coupled Eulerian–Lagrangian (CEL) model is employed to simulate the vertical tunneling process. By conducting a sensitivity analysis, a balanced compromise is obtained between precision and computational efficiency, revealing that a simulation velocity of 0.4 m/s and a mesh density of 0.12 D could facilitate a balance. Based on the CEL results, the failure mechanism during vertical tunneling is categorized into four phases: local soil compression, extended shear failure, progression of the shear face across the ground surface, and soil redistribution. The shape of the failure zone changes from a small conical frustum to a large conical frustum across these phases. The corresponding jacking distance, which characterizes the differences between these phases, is determined. To facilitate jacking force calculations during vertical tunneling, the upper diameter of the conical frustum is considered, and an empirical shear failure method is proposed. Four constituents of the jacking force can be calculated directly instead of inverse calculation from measured values. Additionally, it is compared with prior research, such as the shear failure method, and the results emphasize the superiority of the empirical shear failure method in generating precise jacking force predictions. By applying the empirical shear failure method, the impact of the construction time, the external diameter of the standpipe, and the standpipe length on the jacking force are analyzed. The conducted validation reinforces the credibility and effectiveness of the proposed approach within the broader scope of vertical tunneling analysis. [ABSTRACT FROM AUTHOR]

As the integration of renewable energy sources (RES) progresses and energy technologies advance, integrated energy systems (IES) have emerged as a practical solution for leveraging RES and balancing local demand–supply dynamics. This paper investigates the planning and optimization of operations for an electricity-hydrogen integrated energy system (EH-IES), considering degradation and multi-timescale operations of storage devices to minimize the life cycle costs. To mitigate computational challenges, the planning model adopts a Representative Time Period (RTP) framework, and a novel intertemporal operation model is developed to coordinate the operations of battery and hydrogen storage. Furthermore, we propose a two-stage approach to derive representative weeks and hours from meteorological and load data using fewer data points, ensuring chronological coherence and preserving long-term patterns to validate storage device constraints and improve planning accuracy. Case studies in southeastern China's IES verify the effectiveness of our planning approach, which lowers equivalent annual costs by 4.5% and reduces battery capacity needs by 12.8%, thereby highlighting its significant economic benefits. Additionally, numerical analyses reveal that our two-stage method surpasses conventional RTP selection techniques, delivering at least 10% less average error with an equal number of operating points. • A novel planning and intertemporal model of EH-IES based on representative time periods is established. • The multi-timescale operations of the battery and hydrogen storage system is considered. • An efficient and accurate representative time-period selection method is developed. [ABSTRACT FROM AUTHOR]

[Display omitted] Particulate matter (PM) is an important air pollutant in subway systems. Exposure to high PM concentrations poses a threat to human health and raises concerns. Piston effect can provide the outdoor fresh air to subway stations through station exits, but it also brings PM from tunnels to platforms when the train enters the station. In this paper, a transient numerical model is developed according to an actual subway station and validated by field tests. The model is used to investigate PM 10 concentration at platform induced by train movement. The cumulative PM 10 concentration at platform in one day is calculated according to the train schedule. Platform screen door (PSD) with adjustable vents is studied to control the PM 10 level at platform and energy saving in 27 cities of five climatic zones in China are discussed. The results show that adjustable vent height should be less than 0.70 m to ensure that PM 10 concentrations at platform can be maintained at an acceptable level and the requirement of fresh air can be met. Moreover, energy consumption can be reduced by more than 70 % in different cities compared with the conventional mechanical ventilation system. The optimized adjustable vent can provide an important reference for improving indoor air quality (IAQ) and saving energy consumption of ventilation systems in underground facilities. [ABSTRACT FROM AUTHOR]

Hydraulic fracturing technology has become an effective technical method of developing tight oil reservoirs, such as an oilfield in Mahu, China. However, numerical simulation of the actual fracture seam network remains problematic. In this paper, we have simulated hydraulic fractures in the Urho Group of the Mahu target layer and analyzed the characterization of the rock mechanics parameters. The results show that Young's modulus of the Wuerhe domain ranges between 18 and 58.5 GPa, with an average of 32.4 Gpa, the Poisson's ratio is between 0.21 and 0.38, with an average of 0.31, the brittleness index is between 21.0 and 89.0, with an average of 44.3, and the hydraulic fracturing can form a multi-branch crack modification. The designed direction of horizontal wells in the area is north-south, and the horizontal stress difference is between 4.2 and 9.8 MPa, which facilitates easy fracturing of the reservoir and reforming of a complex seam network. Simulation of the artificial seam network helps to optimize the reasonable parameters of fracturing and the development parameters of horizontal wells in the Mahu 1 well area. [ABSTRACT FROM AUTHOR]

Owing to the heavy rainfall, a landslide occurred at the Anqian Iron mine, at 18:00(UTC + 8) on November 24, 2019, in China. The landslide was about 3.0 × 104 m3 and caused damage to the road of transporting waste materials. Failure characteristics and the mechanism of this landslide were analyzed in this study. The landslide area was divided into three parts: the rear tension cracking area, the middle sliding deformation area, and the front colluvium area. A contact-free measuring technique using the new ShapeMetrix3D system was applied and 204 joints were analyzed based on equal-angle stereographic projection. Thus, a conceptual model of the mechanism of the landslide was constructed and the formation process of the landslide was divided into three stages: the first shearing and dislocation stage; the second sliding, front bulging, and rear tractive cracking stage; and the third local rock mass collapse and colluvium depositing stage. Numerical modeling was performed to discover the landslide mechanism by progressively reducing the shear strength of rock mass. The results showed that the original slope was stable, whereas heavy rainfall triggered the landslide, and the predicted failure surface matched closely the field investigations. The factor of safety obtained by real three-dimensional analyses was slightly higher than that obtained by plane problem analyses, and the difference was attributed to the three-dimensional effect of the landslide. This paper also presents the results obtained from the parametric analysis in order to understand the impact of shear strength parameters on the overall stability of the slope. [ABSTRACT FROM AUTHOR]

The peak particle velocity (PPV) is an important indicator for predicting blasting excavation disturbances. However, the PPV distribution in the deep underground space is significantly different from that on the outdoor ground. Therefore, it is difficult to predict the underground PPV by Sadovsky's vibration formula. The PPV sidewall distribution characteristics were studied during site blasting in an underground cavern in the Taohuazui mine in China, and a similar numerical model was used to verify the site test data. We derived a PPV prediction formula for the underground cavern sidewall surrounding rock using a mechanical analysis model of a simply supported plate and beam in combination with dimensional analysis. The model considered derived boundary constraints, comparison with site measured data, the value predicted by Sadovsky's vibration formula, and numerical simulation results. The results showed that the PPV distribution on the middle 1/3 section of the underground cavern sidewall showed a "platform" or "bulge" different from the curve from Sadovsky's vibration formula. The PPV amplification coefficient in this section was distributed in a drum shape. The PPV prediction formula for the middle section of the sidewall derived in this paper was highly consistent with the data measured on-site and the numerical simulation results. The mechanical analysis model with a simply supported plate and beam included an underground cavern sidewall length–height ratio of 5 and effectively supplemented the PPV prediction formula for the middle section of the traditional underground cavern sidewall. [ABSTRACT FROM AUTHOR]

Coastal short-term cruise products are matched with Chinese consumer demand characteristics. Launching coastal short-term cruise products can help local Chinese cruise companies change the monopoly status of foreign cruise companies in China. This paper builds a two-stage optimization model to provide a decision-making method for local Chinese cruise companies. The first stage determines the itinerary scheme, with the goals of minimizing the cost and maximizing the potential demand. The second stage determines the cabin price, with the goal of maximizing the profit of the cruise company. The model considers the competition of cruise products and their alternative products based on consumer preferences. In the case study, we take Dalian Port as the home port to do the numerical analysis. The results show that coastal cruise products with journey times of 2–3 days have the highest market penetration and are more profitable. [ABSTRACT FROM AUTHOR]

The oil-water and gas-water relative permeability curves are important reference data for the dynamic analysis and numerical simulation of oil and gas reservoir exploitation. Although the petroleum industry of China and other countries have formulated reference standards for the measuring methods of relative permeability of cores, they haven't given the definite reference values of the core length, therefore we cannot know for sure whether different core length values are required in the measurement and whether the core length has an impact on the measurement results. In view of this gap, this paper conducted a research on the relative permeability of cores with different lengths. The core samples are artificial core with similar properties as the outcrop cores of the Halfaya Oilfield (Iraq), in our experiment, the oil-water and gas-water relative permeability curves of the sample cores were measured and the results suggest that, for the oil-water relative permeability curves, as the core length grows, the iso-permeability points move to the right, and they basically stabilize when the core length is greater than 20cm; as for gas-water relative permeability curves, in case of low-permeability cores, under constant injection pressure, as the core length grows, the iso-permeability points and the two-phase co-permeation areas present an obvious tendency of moving to the left, but when the core length is greater than 20cm, such tendency is not obvious, and the high-permeability cores do not have such characteristics. These results indicate that, the unsteady-state two-phase relative permeability measurement experiments obtained accurate results at a core length of about 20cm, which provided a reference for similar experiments in subsequent research. [ABSTRACT FROM AUTHOR]

There have been reported cases of wellbore instability near-wellbore area due to failures associated with drilling operations, the magnitude and extension of the failure area is imprecisely evaluated by copious researchers due to some of the limitations posed by the numerical simulations used. Therefore, this paper estimates a failure zone area near-wellbore based on the conducted coupled Thermal-Hydro Mechanical (THM) analysis integrated into UDEC, wellbore enlargement, and Failure area analysis. A two-dimensional horizontal plane stress model of 2 × 2 m is created using rock properties from a vertical well, and a wellbore radius of 0.11 m is drilled under confined stress using the in-situ stresses. The Voronoi tessellation joint system was used to create randomly polygon fractures referred to as Discrete Fracture Size (DFS). The coding of various parameters was performed to study the near-wellbore stability for both underbalanced and overbalanced drilling conditions, the four cases of DFS were used against seven wellbore pressures. After comparing with other DFS, The parametric analysis at DFS of 0.1 and 0.12 m offers low shear and block displacements that led to an induced shear and tensile failures, respectively. However, to evaluate the optimal DFS, a comparison is done using Failure area and Borehole enlargement analysis, and the results show that DFS of 0.12 m yields significantly low wellbore enlargement rate and failure area zone for all stress ratios and drilling cases. The proposed simple model for wellbore failure area estimations is verified against a well vertical section located in Northern China. [ABSTRACT FROM AUTHOR]

Fully-mechanized mining of coal face with a large cutting height is generally jeopardized by rib spalling disaster in the working face. Preventive measures based on undisturbed coal seam conditions fail to provide safe predictions, as large-scale fractures in soft coal face frequently appear before excavation due to mining-induced stresses. This paper investigates a case study of the Paner Mine 11224 working face in the Huainan mine area, China, which features an overlying protected layer in the protective seam mining. To simulate the failure process in such a mine, we elaborated a simplified physical-mechanical model of a coal wall that underwent shear failure and sliding instability, in compliance with the triangular prism unit criterion. Similar simulation experiments, theoretical calculations, and borehole monitoring were used to comprehensively analyze the overburden fracture and movement after mining the lower protective seam. The development height of three overburden zones was determined, and the characteristics of the protected layer affected by mining were obtained. The results show that the failure is mainly related to the roof load, coal cohesion, internal friction angle, coal seam inclination, and sidewall protecting force. The key to limiting the frictional sliding of a slip body is to reduce the roof load and increase the sliding coefficient and cohesion of the main control weak surface (MCWS). Besides, a self-developed three-dimensional numerical calculation software RFPA3D (Realistic Fracture Process 3D Analysis), which considered the rock heterogeneity, was used to reproduce a weak triangular prism's progressive failure process. The numerical simulation results agreed with the fracture pattern predicted by the theoretical model, which accurately described the rib spalling mechanisms in a soft coal face with a large cutting height and a protective layer. [ABSTRACT FROM AUTHOR]

The hardening soil (HS) model is the most commonly used constitutive models of soft soil of foundation pits of PLAXIS software in numerical analysis, and its parameters are prerequisite for accurate calculation. In this paper, relevant parameters of the HS model in Shenzhen Bay in China were studied through one-dimensional consolidation tests and triaxial shear tests. Analytical methods of reference secant stiffness and failure ratio of soft soil were systematically studied, the influence of shear rates on reference secant stiffness and failure ratio of soft soil was analyzed, and the relationship between stiffness parameters and compressive modulus of soft soil was established. The results showed that reference secant stiffness and failure ratio of soft soil obtained by different analytical methods were quite different, and the errors of reference secant stiffness and failure ratio of soft soil obtained by stress-strain curves were the smallest and the stability was the best; at the same time, with increase of shear rates, the peak deviator stress and reference secant stiffness of soft soil increased, but failure ratio did not change much. The research results could provide a reference of parameter analysis of soft soil for the HS model in the numerical analysis and similar working conditions of foundation pits. [ABSTRACT FROM AUTHOR]

The negative pressure feedback jet sprinkler is a new type of irrigation sprinkler independently developed by China. Its design principle is based on the Coanda Effect. Pulse (including pulse frequency and pressure amplitude) is an important feature of the sprinkler, which has a significant impact on the sprinkler's range, rotation characteristics and spray uniformity. At present, the mechanism of its influence on pulse characteristics has not been systematically studied. The main factors affecting the pulse characteristics of the sprinkle are ratio of the shortest distance between inlet and side wall to inlet width (SW), ratio of distance from inlet to concave to inlet width (HW) and sidewall inclination. In this paper, firstly, design interval of the pulse characteristic structure was obtained through 125 sets of numerical simulations. Secondly, by studying the influence of different factors on the pulse characteristics, the effects of main factors on the pulse frequency and pressure amplitude were obtained. The pulse frequency decreased with the increase of SW and HW, and the values of SW at the turning point of the falling rate was 0.525 and 9 respectively; The inclination of the sidewall inclination had little effect on the pulse frequency; The pressure amplitude increased with the increase of SW, and the value of SW at the point where the growth rate became smaller was 0.450. The pressure amplitude increased first and then decreased with the increase of sidewall inclination and HW, and the value of sidewall inclination and HW at the turning point was 12° and 9, respectively. Based on the above studies, a better design interval for the pulse characteristic structure was further determined. Finally, through four-factor three-level orthogonal test, pulse frequency and pressure amplitude were used as evaluation parameters, and range analysis and comprehensive scoring methods were used to obtain the sprinkler structure with optimal pulse characteristics and they were the shortest distance between inlet and side wall of 1.80 mm, the sidewall inclination of 10°, and the distance from inlet to concave of 28.0 mm. Furthermore, the computer simulation of the sprinkler under the optimal structural parameters was carried out. The numerical simulation obtained the pressure flow diagram during the working process of the sprinkler. A periodic dynamic analysis of the pulse formation process was performed through the pressure flow diagram. At the same time, the pressure difference between the two sides of the main jet was measured during the simulation. The results showed that the maximum positive pressure on both sides of the main jet appeared near 63 mm from the nozzle cross section at different working pressures. This was because the entrainment of the high-speed water flow when the jet was attached to the wall created a strong vortex flow near the wall of the attachment point, which caused a large pressure difference. The maximum negative pressure appeared at a distance of 40 mm from the sprinkler inlet, which was caused by the movement of the deflection in the control tube caused by the uneven pressure difference between the two sides of the jet when the jet was attached to the wall. The pressure difference across the jet at a distance of 70 mm from the sprinkler inlet was also negative, which was mainly caused by the jet deflected into the nozzle, hitting the inner wall of the sprinkler and forming a local vortex. In sum, with the same internal structure design, the position of the attachment point of the sprinkler under different pressure conditions remained basically unchanged. This study provides guidance to optimization of sprinkler structure and to improvement of sprinkler performance according to the characteristics of the high-speed jet Coanda. [ABSTRACT FROM AUTHOR]

The friction pendulum bearings (FPB) begin to be used in railway bridges in China. In one earthquake region in China, the shear pins of FPB are required to be well to provide the enough shear force and stiffness under service loads (such as the vehicle forces being less than 170 kN in the longitudinal direction and 40 kN in the transverse direction) or small earthquake loads with a peak ground acceleration (PGA) being less than 0.1 g, however, are cut off to isolate seismic energy under large earthquake loads with a PGA being larger than 0.2 g. It is necessary to identify the appropriate strength of FPB shear pin to satisfy the above requirements. This paper selected the simply supported bridges on a single-line railway in the above earthquake region as the study object, which had a span length of 32 m and two height types of piers (8 m and 25 m). A prototype finite element model (FEM) and a scaled FEM were numerically analyzed, and a scaled experimental model was tested on shake table for each bridge. The results of them were compared with each other to validate the rationality of all models and to achieve the appropriate strength of FPB shear pin. The results show that the appropriate strengths of FPB shear pins are 540 kN in the longitudinal direction and 300 kN in the transverse direction for the bridge with the pier height of 8 m. Likewise, 350 kN and 270 kN are determined as the appropriate strengths of FPB shear pins for the bridge with the pier height of 25 m in the longitudinal and transverse directions, respectively. The numerical method of FEM is correct based on the experimental validation, and can be used to identify the appropriate strengths of FPB shear pins for other railway bridges. [ABSTRACT FROM AUTHOR]

In recent years, most researches focus on the same height at the bottom of both main and side canal to study the hydraulic performance of water diversion. However, in practice, the height of main and side canal bottom are different in most irrigation districts. In this paper, the effect of the height of the side canal bottom on the hydraulic performance of bleeder was studied. The prototype test was carried out in Northwest A & F University in Yangling, Shannxi of China. In the prototype test, both the main channel and side channel were rectangular. The length of the main channel was 12-m long and 0.46-m wide. The length of the side channel was 2.5 m, and the width was adjustable in the range of 0.46-0.14 m. The elevation of the side channel was 0.06, 0.08 and 0.1 m higher than the bottom elevation of the main channel. A total of 8 flow sections were set up, 5 of which were at the water inlet. In order to analyze the water surface variation at the water diversion of the main channel, 3 measuring points at section I, section II, section III, section IV, section V, section VI were taken. The 3 measuring points were on the center line and 5 cm away from the wall of the main channel on both sides. The variables in the test were the side channel width and the flow rate. The water depth and velocity were determined at the measuring point. To eliminate the influence of boundary conditions, this study simplified the experimental channels. The width of the simulated main and side channels was the same as the actual width of the main and side channels. However, the lengths of the main and side channels were correspondingly extended on the basis of the actual channel length, which were 12 and 5m respectively. Because the flow field near the water-diversion changed drastically, the grid interval at the area was decreased, the cell length was 0.01 m, the remaining area cell grid was 0.02 m, and the total grid number was about 900 000. In the channel model, the inlet boundary of the main channel was set to several volume flow rates, which were 19.96, 25.2, 30.2, 36.5 and 45.32 L/s, respectively; the outlets of the main channel and the side channel were set to be free; the side wall of the channel was selected to have no sliding wall; the air above the free surface was air, and the relative pressure was 0. Based on experiments, FLOW-3D was used to simulate and calculate several flow rate and heights on the rectangular channel water diversion, compared to the measured water depths and velocity. The results showed that the variation of velocity was basically consistent with the measured value and relative error was less than 10%. It was reliable to make numerical analysis on water diversion by using FLOW-3D. The numerical simulation showed that the fluctuation of water surface at the water diversion was affected by the flow rates from the main channel. With the increasing of the bottom height, the maximum velocity and water depth of the side channel inlet section gradually decreased. At the entrance of the side channel, the turbulent kinetic energy near the upstream end was large, while at the downstream end of the branch, the turbulent kinetic energy near the bottom was small. The study provides information on water distribution and water-quantity control in irrigation area. [ABSTRACT FROM AUTHOR]

Based on the rock mass quality classification, this paper proposes a new prediction formula for the attenuation parameters of blasting vibration velocity in jointed rock masses. A parametric sensitivity study is also conducted while considering a variety of influence factors, including joint angle, joint spacing, and joint stiffness. Compared to the existing blast-related standard in China, in which the attenuation parameters are merely derived from rock hardness, without considering the joint characteristics of rock masses, the proposed prediction formula is proved to be a more promising approach to carry out accurate blasting design and blasting safety assessment. [ABSTRACT FROM AUTHOR]

The impact of twin shields tunneling undercrossing with an oblique angle on the existing tunnels is complicated and still lacks of understanding. This paper investigated the deformation behaviors of the existing tunnels with new twin tunnels construction undercrossing obliquely based on numerical simulation on a case history in Changsha, China. The accuracy of numerical analysis was verified in comparison with the field measurement. The variation of the ground settlement trough and the earth pressure acting on the existing tunnel during the shield tunneling was analyzed. Then, the transversal deformation, internal forces and torsion behavior of the existing tunnels induced by the new tunnels excavation were obtained. Additionally, a parametric study was conducted to investigate the impact of the intersection angle between the new and existing tunnels on the deformation behaviors of the existing tunnel. The results show that due to oblique intersection, the transversal deformation and internal forces of the existing tunnel show obvious asymmetrical characteristic, and an unrecoverable local torsional deformation of the existing tunnel on both side of new tunnel can be observed after shield tunneling. The parametrical analysis indicates that the intersection angle significantly influences on the maximum settlement of the existing tunnel bottom, which is up to 27.53% larger in parallel case than that in perpendicular case, and decreases rapidly as the interaction angle varies from 30° to 60°. Nevertheless, the maximum settlement of the existing tunnel crown is unaffected by the intersection angle. [ABSTRACT FROM AUTHOR]

The increase in extraction height will increase the mining‐induced overlying strata failure height. In this scenario, the strata pressure behavior is strong in a fully mechanized face with large mining height (FMFLMH), which frequently causes coal wall falls, roof falls, and hydraulic support failure accidents (e.g., support closure and hydraulic column damage). The key to solving these issues is to determine support's working resistance of the FMFLMH. In this paper, comprehensive theoretical analysis, numerical simulation, and field observation were applied to determine the support's working resistance in the FMFLMH based on movement type of the first subordinate key stratum (SKS 1). First, six kinds of movement types of SKS 1 in the FMFLMH are found and defined by theoretical analysis and numerical simulation, which are the direct caving movement type of cantilever structure (direct caving), the double‐sided rotation movement type of cantilever structure (double‐side rotation), the quadratic rotation movement type of cantilever structure (quadratic rotation), the alternative movement type of cantilever structure hinged structure (alternate hinged), the voussoir beam structure movement type (voussoir), and the short voussoir beam structure movement type (short voussoir), respectively. Besides, based on this, the support load calculation model of each movement type was established, and a formula for the support working resistance of each movement type was obtained. Finally, the correctness of the formulae for the support working resistance under six types of movement of SKS 1 were verified using measurement data from four FMFLMHs in China. These research results have important guiding significance for reasonable selection of support and ensuring safe mining of the FMFLMH. [ABSTRACT FROM AUTHOR]

Abstract A high-fill slope located in Zhenxiong County, Yunnan Province, China, was designed for building placement on its top platform. A reinforcement system consisting of a geogrid, front stability piles (FSPs), retaining sheets, prestressed anchors, and rear deeply buried piles (DBPs) has been used to stabilize the slope. Two typical slope sections were selected to study the high-fill slope stability and retaining mechanism of the reinforcement system. Field measurements of the horizontal displacement and strain in the piles, as well as the anchor working load, were collected and analyzed. In addition, a series of two-dimensional finite element method (FEM) analyses combined with a strength reduction technique was conducted to analyze two selected cross sections. The results show that the retaining structure behavior is closely related to the fill construction process of a high-fill slope. The deflection of the stabilizing pile increases almost linearly with the filling height in the initial stage of fill construction. The variation in the working load of the prestressed anchor shows an offset between prestress loss and increasing fill pressure. The FEM results can provide insight into the pile-soil interaction mechanism and its contribution to fill slope stabilization. The FSPs shift the sliding surface from through the slope toe to through the top of the FSPs. The anchors can reduce the bending moment by supplying additional bearing points. The DBPs can share a portion of the sliding thrust and effectively enhance the safety factor. This paper provides a reference for reinforcement system design for similar engineering projects considering high-fill slopes. Highlights • A case of reinforcement and monitoring for a high-fill slope is presented. • The reinforcement system includes two rows of piles, retaining sheets and anchors. • The behavior of the reinforcement system is investigated through field measurements. • The reinforcement mechanism is analyzed by FEM combined with monitoring. • This study provides a reference for the design of similar high-fill slopes. [ABSTRACT FROM AUTHOR]

The Qianjiangping landslide occurred on July 13, 2003 when water level in the Three Gorges Reservoir in China reached 135 m a.s.l. for about 1 month. Thirteen people on the slope and 11 fishermen on boats in the nearby area were killed by this landslide and its wave. As a typical case, the Qianjiangping landslide is researched extensively, but the wave itself was studied much less. In this paper, a fluid-solid coupling model based on general moving objects (GMO) collision model and renormalisation group (RNG) turbulent model were employed, simplifying the sliding motion of the Qianjiangping landslide as a rigid body circular motion whose validity was verified by comparing with actual survey conditions related. Numerical simulation analysis shows that in the Qianjiangping landslide event, the solid-fluid energy-transferring rate was 5.97 %, while the motion of sliding mass could push and raise water body. The maximum-modelled wave run-up generated by the Qianjiangping landslide was 40.4 m (up to 175.4 m a.s.l.), while the maximal observed one was 39 m. It was the solitary wave, and the wave celerity was 32∼36 m/s or so. The hazardous river length of impulse wave was estimated to be 12.6 km, where wave height was more than 1 m high. The fluid-solid coupling numerical model employed by this paper can provide important reference for wave generated by other landslides around the world. Research of the landslide-generated wave is very significant in landslide hazard reduction and prevention. [ABSTRACT FROM AUTHOR]

This paper predicts the possibility of water inrush from a confined aquifer under the action of mining activities and water pressure. The study uses numerical analyses to evaluate stress redistribution and crack growth which result from coal extraction operations. Two models are presented in this study. By simplifying the distribution of the disturbed vertical stress on the coal seam and floor around a working face, a model is established to analyze the additional stresses in the floor strata induced by mining activities. And some distribution features of all the additional stress components are described. By using the superposition principle in fracture mechanics, another model is developed to analyze the crack growth in the floor strata under the action of disturbed stresses and water pressure. And the stress intensity factors at the crack tip are presented and the process of crack growth is obtained in the advancement of a working face. Because of discretizing only loading areas and crack surfaces, the present methods can obtain the accurate numerical results. Finally, some suggestions are made for preventing the water inrush from a confined aquifer. [ABSTRACT FROM AUTHOR]

Many fresh produce retailers in China apply a Replenish-to-order (RTO) selling mode when purchasing replacement produce. In a RTO mode, retailers replenish produce after receiving customers’ orders from the internet. In this paper, we first compare two solutions when retailers apply a RTO mode and face a lack of capacity in the physical store. Results show that retailers need to buy temporary space to fulfill customers’ orders. Then we compare two selling modes: RTO and Replenish-to-stock (RTS). In a RTS mode, retailers replenish and stock produce in advance and wait for customers to buy the produce. We find that produce spoilage and customer waiting cost are two significant differences between the two selling modes. Numerical analysis demonstrates that the RTS mode is more profitable in most cases. However, when customers get used to the RTO buying process, the RTO selling mode can be more profitable. [ABSTRACT FROM AUTHOR]

This article presents a study of water-heat coupled problems of frozen soil along the Mohe-Daqing crude oil pipeline with thermosyphons. It is known that the Mohe-Daqing pipeline goes through four different kinds of frozen soil classified by ice content in soil. To determine the region with high tendency of permafrost thawing, the temperature field and water content field of the four types of frozen soil were first investigated in this paper. Taking freezing and thawing risk, typical geological condition and other factors into consideration, the soil temperature field of pipeline located at the permafrost swamp area was calculated numerically. Comparative study was also carried out for soil temperature field with and without thermosyphons to investigate the cooling effect of thermosyphons. It is evident that thermosyphons have great influence on temperature drop of permafrost, and this influence is especially magnificent in winter. In contrast to soil temperature without thermosyphons, installing the thermosyphons could reduce the soil temperature right beneath the pipeline by approximately 4°C. Numerical results, which have been validated by field data, are of great guiding significance for construction and operation safety of pipelines buried in cold regions. [ABSTRACT FROM AUTHOR]

This paper presents a finite element analysis for the behavior of the Lianghekou high earth-core rockfill dam, which was just completed in construction in China. An elastoplastic constitutive model that can account for the degradation of rockfills due to particle breakage (hhu-SH-breakage model) was applied to simulate the mechanical behavior of the rockfills. The earth-core wall was analyzed by using the modified Cam-clay model combined with the Biot's consolidation theory. Numerical results are in good agreement with in-situ measurements during construction, indicating the reasonability of the numerical analysis. Based on the breakage-packing concept, which is able to extract the breakage-induced deformation from the total deformation, numerical analysis showed that the breakage-induced settlement for the extra high rockfill dam is not negligible. Inspired by the sensitivity analysis using the hhu-SH-breakage model, engineering advices were proposed to reduce the settlement of high rockfill dams. [ABSTRACT FROM AUTHOR]

Goal rock is naturally comprised of a large number of randomly-distributed discontinuities such as joints/ cracks and weak interlayers. The geometry, size, distribution, contact and infillings of the discontinuities essentially govern the physical/mechanical properties and failure mechanism of coal rock. It is intractable to theoretically and accurately characterize the discontinuities and the governing influences on the deformation and failure of coal rock. This paper presented a 3D finite element model of fractured coal rock representing the irregular geometry, complex contact, intersection, and network features of interior joints and cracks by means of high-resolution GT techniques and 3D reconstruction methods. The birth-death clement algorithm was employed to characterize and visualize the stress field distribution, spatial distribution of failed areas, energy dissipation and release during the deformation and failure of fractured coal rock when subjected to the varied unloaded conditions. The analysis discloses the determinative influences of the unloading paths and the properties of joints and cracks on the macro mechanical behavior and the failure mechanism of fractured coal rock. The paper presents a promising way to identify and characterize the governing effect of unloading due to deep excavation on real fractured coal rock. [ABSTRACT FROM AUTHOR]

This paper reviews developments in high-altitude electromagnetic pulse (HEMP) research in China in recent decades. The main contents are obtained from a literature survey of technical papers published in the past years, which include HEMP simulators and test systems, coupling analysis methods and results, experimental research on the susceptibility of electronic equipment, time-domain measurement, and modeling technology. [ABSTRACT FROM AUTHOR]

Abstract: With attractive advantages of high efficiency, energy saving and environmental friendliness, the ground source heat pump (GSHP) system has been used widely in China in recent years. This paper summarizes the analytical solution, numerical solution and experimental investigation of the heat transfer of the ground heat exchanger (GHE), analyzes the simulation model and long-term operation performance of the GSHP system, and introduces the lastest hybrid ground source heat pump (HGSHP) system. In addition, this paper discusses and summarizes the shortages and imperfects of the current research on the simulation of the GSHP system and gives some recommendations for future work. [Copyright &y& Elsevier]

Abstract: There were several tendons breakout on bottom slabs happening during construction stage of continuous pre-stressed concrete bridges in recent years in China. The paper studies one case based on numerical simulation that happened on a 47+75+47m continuous pre-stressed concrete rigidframe bridge. In this paper, both linear elastic and nonlinear inelastic analysis are developed, concrete and reinforcements stress levels before and after pre-stressed tendons stressed are compared, and the path of crack appearance are revealed by calculation. The effects of the incorrect arrangement of reinforcement during construction are also analyzed, which is proved not to be the leading reason of the failure. The outcomes of the finite element analysis indicate that oversize of the longitudinal prestressed tendons and unreasonable sizes of the bottom slab are the main reasons of the failure. Some advices to avoid similar accident are given for future design. [Copyright &y& Elsevier]

The time-band approximation model for flight operations recovery following disruption (Bard, Yu, Arguello, IIE Transactions, 33, 931–947, 2001) is constructed by partitioning the recovery period into time bands and by approximating the delay costs associated with the possible flight connections. However, for disruptions occurring in a hub-and-spoke network, a large number of possible flight connections are constructed throughout the entire flight schedule, so as to obtain the approximate optimal. In this paper, we show the application of the simplex group cycle approach to hub-and-spoke airlines in China, along with the related weighted threshold necessary for controlling the computation time and the flight disruption scope and depth. Subsequently, we present the weighted time-band approximation model for flight operations recovery, which incorporates the simplex group cycle approach. Simple numerical experiments using actual data from Air China show that the weighted time-band approximation model is feasible, and the results of stochastic experiments using actual data from Sichuan Airlines show that the flight disruption and computation time are controlled by the airline operations control center, which aims to achieve a balance between the flight disruption scope and depth, computation time, and recovery value. [ABSTRACT FROM AUTHOR]

Abstract: Snow cover is a common and relatively stable land cover condition in winter for cold north regions in China. Snow cover has significant effects on water and heat transfers in frozen soil; it needs to be considered in the study of frozen soil water–heat coupled movements. On the basis of previous research results and physical process analysis of water and heat movements in snow cover and soil, a snow cover–soil union water–heat coupled movements model is established in this paper. The numerical simulation was conducted by using a finite difference method. The results indicate that the simulated values have a similar trend to the measured values and the numerical simulation had big relative errors. However, the average absolute errors of the total and liquid moisture content in frozen soil were all less than 4%, and that of the frozen soil temperature was 1.37 °C. The errors of the numerical simulation were still within the acceptable range. Thus, the snow cover–soil union water–heat coupled movement model constructed in this paper is rational. [Copyright &y& Elsevier]

Abstract: Since the thermophysical properties of water change dramatically at near-critical and pseudocritical point, the instability of natural circulation at supercritical pressure may occur in a loop. To predict the region of instability of natural circulation at supercritical pressure, a test loop was built at Tsinghua University. The paper presents the information of the test loop and a numerical analysis model for the loop. The paper verified the numerical analysis code by experiment results and using the code to analyze the instability of the loop. The paper concludes conclusion that there will be no Ledinegg instability occurring at supercritical pressure in the loop. [Copyright &y& Elsevier]

Abstract: This paper investigates numerical method for predicting wind field and pollutant dispersion in an urban area with crowded buildings and heavy traffic. Large eddy simulation is employed in numerical computation with Lagrangian dynamic model to close the subgrid scale stress. The fine grids are required in numerical simulation of micro-atmospheric flows in an urban area with crowded and complex building-streets. To realize the numerical simulation on available computer resources a domain decomposition method and a combined model for the building-street layout are proposed that the computed domain of an urban area is decomposed into a central area, where the pollution is the major concern and a surrounding region where the pollutant distribution is not concerned. The combined flow model is proposed for the complex building-street layout that the fine grid mesh and exact flow boundary conditions are prescribed in the central area while the buildings are treated as roughness elements in the surrounding region where the coarse grids are used. The proposed numerical method is applied to simulate the wind field and pollutant dispersion from vehicle exhaust in the Rua Do Campo area of Macau (referred to the site hereafter). The wind speed and temperature fields are computed from 7 am on September 6 2005 to 7 am of the next day and the pollutant concentration field is computed from 7 am to 6 pm on September 6 2005. The results show fairly good agreement with the field observation. The wind field and pollutant concentration distribution are demonstrated in the site by proposed combined model and they are compared with those computed by drag element model in whole computational domain. The results show that the combined model is an appropriate method for predicting wind field and pollutant dispersion in the crowded building area. The paper also reveals the relevance of buoyancy effect in the prediction of urban atmospheric environment. [Copyright &y& Elsevier]

Abstract: In order to investigate the steady heat transfer characteristics of a porous media solar tower receiver developed in China, this paper applies the steady heat and mass transfer models of the porous media to solar receivers, chooses the preferable volume convection heat transfer coefficient model, solves these equations by using the numerical method, and analyzes the typical influences of the porosity, average particle diameter, air inlet velocity, and thickness on the temperature distribution. The following conclusions have been drawn: in the same position or relative position along the downstream, the bigger the average particle diameter is, the higher the solid matrix dimensionless temperature is, the higher the air dimensionless temperature is. The bigger the porosity is, the lower the solid matrix dimensionless temperature is, the bigger the porosity is, the higher the air dimensionless temperature is. The bigger the thickness is, the lower the solid matrix dimensionless temperature is, the higher the air dimensionless temperature is. In a certain depth, the bigger the air inlet velocity is, the higher the solid matrix dimensionless temperature is. After a certain depth, the bigger the air inlet velocity is, the lower the solid matrix dimensionless temperature is, and the bigger the air inlet velocity is, the higher the air dimensionless temperature is. The paper can provide a reference for this type of receiver design and reconstruction. [Copyright &y& Elsevier]

Abstract: Modelling of a complex carving surface is the most important process for digitization of art carving such as Chinese classical furniture carving, and it is difficult to be fulfilled. However, a complex 2D curve flower pattern can be easily acquired or drawn by handcraft or a drawing software. This paper presents a quick integrative 3D modeling method of complex carving surface based on a 2D curve flower pattern. The proposed method uses a scanning analysis algorithm, a normal distribution function and a distance function to model and create carving tracks. In this paper, the delamination, combination and interpolation of modelling process are described as well. The provided research method will make the modelling of complex carving surface more intelligent, agile, and will meet the requirement of integrative 3D modelling of digital art carving. Experimental results show that this method is of quick modelling and multi-model effective characteristics with realizable interactive designing and excellent practicability. [Copyright &y& Elsevier]

A procedure for the simultaneous estimation of an origin–destination (OD) matrix and link choice proportions from OD survey data and traffic counts for congested network is proposed in this paper. Recognizing that link choice proportions in a network change with traffic conditions, and that the dispersion parameter of the route choice model should be updated for a current data set, this procedure performs statistical estimation and traffic assignment alternately until convergence in order to obtain the best estimators for both the OD matrix and link choice proportions, which are consistent with the survey data and traffic counts.Results from a numerical study using a hypothetical network have shown that a model allowing θ to be estimated simultaneously with an OD matrix from the observed data performs better than the model with a fixed predetermined θ. The application of the proposed model to the Tuen Mun Corridor network in Hong Kong is also presented in this paper. A reasonable estimate of the dispersion parameter θ for this network is obtained. [Copyright &y& Elsevier]

This article compiles the actual knowledge of the biogenic volatile organic compound (BVOC) emissions estimated using model methods in the Pearl River Delta (PRD) region, one of the most developed regions in China. The developed history of BVOC emission models is presented briefly and three typical emission models are introduced and compared. The results from local studies related to BVOC emissions have been summarized. Based on this analysis, it is recommended that local researchers conduct BVOC emission studies systematically, from the assessment of model inputs, to compiling regional emission inventories to quantifying the uncertainties and evaluating the model results. Beyond that, more basic researches should be conducted in the future to close the gaps in knowledge on BVOC emission mechanisms, to develop the emission models and to refine the inventory results. This paper can provide a perspective on these aspects in the broad field of research associated with BVOC emissions in the PRD region. [ABSTRACT FROM AUTHOR]