Meniscus water affects the shear strength of unsaturated soils. The soil wettability affects the physio-mechanical behavior, the contact angle and the capillary pressure. The current geotechnical knowledge of these effects in unsaturated soils is mostly limited to hydrophilic soils. This paper analyzed hydrophobic and hydrophilic sands to show how meniscus water affects the shear behavior of unsaturated soils using artificially synthesized hydrophobic sands. In addition, the measured shear strengths were analyzed based on the suction stress. The results show that the meniscus water greatly influences the unsaturated shear behavior. The shear strength and dilatancy of hydrophilic sands are greater than those of hydrophobic sands. For hydrophobic sands, the water in the soil is not in the form of meniscus water, but in the form of water droplets on the particle surface. Therefore, the initial saturation has little effect on the shear strength, but a large effect on the dilatancy. For hydrophilic sands, the shear strength increases with decreasing initial saturation.

The shear resistance of rock-filled concrete (RFC) interlayers depends on the interaction between the exposed rock corners and the surrounding self-compacting concrete (SCC). This study uses 24 small direct shear tests of RFC joints to analyze the effects of the aggregate strength, exposure height and number, and normal pressure on the shear behavior of RFC joints. The results show that the aggregate significantly influences the RFC joint shear strength. Two typical failure modes are observed with compressive plastic failure of the SCC and direct shear failure of the shear rocks. The exposed height, number and strength of the aggregate as well as the normal pressure all affect the shear capacity and failure mode. Shear stress transfer theory of concrete cracks is used to develop a design method that considers the two failure modes for the RFC interlayer shear capacity. The method is verified by the test results and provides a design method for RFC interlayer shear predictions.

A closed relationship for daily maximum sediment concentration was developed to solve the scale matching problem between the sediment concentration and the flow velocity in the SWAT model. A power function was used to fit the daily flow rate to the sedimentation flux at 9 gauging stations located in the soft sandstone region of the middle Yellow River to provide a closed relationship for the daily sedimentation rate. The closed SWAT model was then used to simulate the sediment transport in the Huangfuchuan watershed of the Yellow River. The model was validated by comparing the observed and simulated sediment loads at the Huangfu and Shagedu stations. The results showed that the Nash-Sutcliffe efficiency coefficient (NSE) was 0.70 and the determination coefficient (R²) was 0.74 during the calibration period and were equal to 0.66 and 0.68 during the validation period for the daily scale sediment load at the Huangfu station. The closed SWAT model predictions at the Shagedu station correlated with the observed sediment load with NSE=0.78 and R²=0.78 for the calibration period and NSE=0.72 and R²=0.74 for the validation period. The unclosed SWAT model had NSE=0.36 and R²=0.39 for the calibration period and NSE=0.26 and R²=0.26 for the validation period at the Shagedu station. The results indicate that the closed SWAT model improves the simulation accuracy for sediment transport within the basin to improve applications of the SWAT model in the soft sandstone region for sediment simulation.

Northwest China is a vast territory with scarce water resources and a fragile ecological environment system. Various water-saving irrigation techniques have been developed that need to be evaluated to facilitate sustainable development. This study presents an evaluation index system for water-saving irrigation techniques in the arid and semi-arid regions of Northwest China that incorporates the ecological vulnerability, economic development, climatic and geographical characteristics, irrigation development trends and labor costs. The model has 23 indicators in total with ecology, economics, adaptability, accuracy and intelligence level as the criterion layer. The analytic hierarchy process and the fuzzy comprehensive evaluation method were combined to determine the weights for the evaluation indicators and evaluation thresholds. The model was then used to evaluate three typical water-saving irrigation techniques, drip irrigation, sprinkler irrigation and small-scale border irrigation. The results show that the economics is the most important followed by the adaptability, ecology, intelligence level and accuracy. The most significant indicators in each of the five criterion layers are the investment per mu, water quantity adaptability, inhibition of groundwater over-exploitation, labor-saving and irrigation water use efficiency. Drip irrigation system is shown to be excellent system for Northwest China, while sprinkler irrigation and small-scale border irrigation systems have average usefulness in Northwest China. The methodology and results can be used for water-saving irrigation technique selection.

Taking the "7.21" flash flood in Hongluogu valley as study object, the effect of sediment transport on flash flood characteristics is investigated by comparing the results of moving-bed model, fixed-bed model and post-disaster survey data. Due to the interaction between sediment and flow, maximum water level under the moving-bed condition is generally higher than that of fixed-bed condition yet maximum flow rate decreases. The possibility of getting flooded in some sections increases and the flooded time of the depositional section extends. Affected by erosion and deposition, the arrival time of maximum water level at partial sections is different from the arrival time of flood peak, which indicates the insufficiency in judging flooding trend throughout the channel by observations from limited monitoring points. These results would play a guiding role in risk analysis and disaster prevention of flash floods.

The logarithmic law is generally accepted to be a universal law for turbulent open channel flows independent of the Reynolds number and Froude number. However, the thickness of the logarithmic area and the value of the Karman constant are still being debated due to the inseparability of the Karman constant and the friction velocity and the gradual changes in the relationship between the mean velocity distribution and the logarithmic law. A diagnostic function is developed in this study to separate the Karman constant and the friction velocity in particle image velocimetry (PIV) data for open channel flows. The diagnostic function for the experimental data shows that the mean velocity distributions have no strict logarithmic region. According to the results of experiments and direct numerical simulation (DNS), the logarithmic region appears only when the Reynolds number is large enough and is within 76 < y⁺ < 0.5 Re_τ. The Karman constant is then between 0.334 and 0.415.

The dynamic integration and management of models are key demands in the construction of the hydro-modeling platform (HydroMP). The corresponding key technologies include a driving model for the platform, data exchange between the model and the platform, real-time control of the model operation and dynamic management of the models. General model integration methods supporting hot-plug modules are used to integrate different types of models into the HydroMP and to meet the needs of different users. An EXE integration method is developed that does not require changes in the existing running mode of the model programs. There is no need to rewrite the original code to realize the model integration using the EXE integration method; only data conversion modules are needed. An interactive integration method is developed that gives real-time communication between model processes and the platform. This interactive integration approach uses a standard communication program to encapsulate the model and generate a new model program. Then, the new model is registered in the platform to realize the model integration and management. The interactive integrated model process provides real-time communication and data exchange with the cloud platform. These two integration methods are applied to the HydroMP to provide dynamic integration and management of different heritage models.

Contact between the driving wheel of a horizontal well crawler and the casing pipe wall causes plastic deformation indentations in the pipe wall. The indentation morphology then greatly influences the crawler motion with the oblique indentation contact between the wheel teeth and the pipe wall being a very complex process. A theoretical model was developed to analyze the indentation formation for various loading conditions with positive pressure and torque on the gear tooth to the oblique indentation. The loading effects can be divided into 6 different action areas. Slip line theory was used to analyze the pressure distribution for various contact states of the gear tooth in each region in a mechanical calculation model relating the load on the gear tooth and the indentation morphology. The critical loads between the action zones are identified with forward and backward application methods of the theoretical model. Finally, theoretical models of the four stabilization zones are characterized based on their indentation depth, amount of slip, indentation morphology and pressure distribution on the contact surface, and the indentation verification test was also carried out. The simulations and tests show that the load division between the gear teeth is reasonable and the theoretical model is accurate. This lays a foundation for optimization of the crawler load control strategy and the modeling and optimization of the multi-tooth traction force on the drive wheel.

The rotational tool center point(RTCP) accuracy is an important evaluation index for evaluating five-axis hybrid machine tools. This study analyzed a 5-axis hybrid machine based on 3P(4R)S spindle head and calibrated the positioning and angular precision of the machine tool terminal to improve the RTCP precision of the hybrid machine tool. This paper presents an identification algorithm, which shortens the identification time compared with the least squares method and the ridge estimation method. Calibration tests show that the parameters identified by the algorithm can effectively improve the machine tool accuracy, which verifies the algorithm effectiveness and lays a foundation for milling using a 5-axis hybrid machine tool.

The ladder diagram is one of the four programmable logic controller (PLC) programming languages defined by the IEC 61131-3 standard. However, since the ladder diagram cannot be directly executed by processors, most commercial PLC programming systems convert the ladder diagram into an instruction list similar to assembly language that is convenient for generating machine instructions. This paper presents a transformation algorithm based on AOV (activity on vertex) and Lists. Unlike in existing List algorithms, this algorithm solves the multi-coil output problem. In addition, a depth-first search algorithm is used to traverse the generated Lists with output flag bits to generate a correct instruction list. The optimal time complexity of the algorithm is O(n), and the worst is O(n²).