Consolidated-isotropically undrained triaxial compression (CIUC) tests were performed on the reconstituted deep clay from a mine in East China. It was consolidated to maximum stresses in the range of 0.3–2.6 MPa. The test results show that the stress-strain-strength properties of the clay during undrained shear are significantly stress-dependent. In particular, in the case of high consolidation pressure, the post-peak drop in strength on stress-strain curves and shear plane in soil specimens are more evident, the peak stress ratio and the axial strain at which this ratio was reached are smaller, and the relationship between pore pressure and axial strain is also significantly different from that for the case of low consolidation pressure. The environmental scanning electron microscope observations and micro analysis lead to an understanding of the physical mechanisms underlying the above stress-dependent mechanical behavior. In addition, the CIUC behaviors of the studied clay are discussed in the context of critical state soil mechanics.

Submerged vanes are low-height flow-training structures emerging from the riverbed with a suitable angle of attack to the incoming flow. These structures redirect the stream flow and modify erosion and depositional rates in the bottom and in the banks of a river as a result of the secondary currents generated by their installation. For this reason they have many applications in river hydraulics for controlling river bed morphology. An experimental investigation is carried out to compare the efficiency of sheet-piling vanes versus thin plane ones in controlling sediment redistribution in the channel bed. In particular, experimental tests were carried out within a straight water channel, in conditions of bed load motion. The morphology of the river bed both in the area close to the structure and in the far field was examined at different angles of attack of the vane to the incoming flow and at different values of the submergence parameter, which is the ratio between the height of the water above the structure and the water level. The experimental results show that both the shape of the vanes as well as the angle of attack affect their performance in terms of the effects on the bed morphology, especially for greater submergence parameters. Specifically, plane and sheet-piling vanes produce comparable remodelings of the channel bed in the downstream region, but when the attack angle is increased, the thin plane vane causes deeper scour holes close to the structure. This last effect is probably due to the increased erosive capacity of the horseshoe vortex associated with the plane vane, while the uneven surface of the sheet-piling vane mitigates the erosive strength of that vortex.

Uncertainty exists widely in hydrological analysis, and this makes the process of uncertainty assessment very important for making robust decisions. In this study, uncertainty sources in regional rainfall frequency analysis are identified for the first time. The numeral unite spread assessment pedigree (NUSAP) method is introduced and is first employed to quantify qualitative uncertainty in regional rainfall frequency analysis. A pedigree matrix is particularly designed for regional rainfall frequency analysis, by which the qualitative uncertainty can be quantified. Finally, the qualitative and quantitative uncertainties are combined in an uncertainty diagnostic diagram, which makes the uncertainty evaluation results more intuitive. From the integrated diagnostic diagram, it can be determined that the uncertainty caused by the precipitation data is the smallest, and the uncertainty from different grouping methods is the largest. For the downstream sub-region, a generalized extreme value (GEV) distribution is better than a generalized logistic (GLO) distribution; for the south sub-region, a Pearson type III (PE3) distribution is the better choice; and for the north sub-region, GEV is more appropriate.

This paper applies digital image techniques to observe the slagging characteristics of blended coals in a pilot-scale furnace. Collected deposit samples were analyzed by scanning electron microscopy linked with energy-dispersive X-ray analysis (SEM-EDX), X-ray diffraction (XRD), and X-ray Fluorescence (XRF) to acquire the microstructure, chemical composition, and mineralogy. The deposit thickness of three blends was analyzed between their parent coal A (Datong) and coal B (Shan), and we noted that the time to reach a stable stage decreased with the ratio of coal B. The addition of coal A into coal B could remarkably restrained the growth and thickness of ash deposits. The results of XRD analysis indicated the initial layer was predominantly comprised of the crystalline minerals quartz, anorthite, or albite except for coal B. All of the blends and coals contained quartz and Ca- to Al-silicates (Ca_0.68Na_0.32)(Al_1.68Si_0.32)Si₂O₈ in the slag layer where iron-bearing minerals (e.g., ilvaite) were altered into an amorphous phase. The result of SEM-EDX suggested that there was an elemental disparity between the coal ash and deposit.

Lamellar tearing and crack-induced brittle failures along steel plates in the through-thickness direction seriously threaten the safety and reliability of steel thick plate structures in construction and service, especially at low ambient temperatures. Three kinds of tests, including uniaxial tensile tests, Charpy V-Notch impact tests, and three-point bending (TPB) tests were performed at normal and low temperatures to investigate the through-thickness mechanical properties, impact and fracture toughness of Q345B structural steel plates with thicknesses from 60 to 165 mm. The test specimens were mainly sampled along the through-thickness direction of the plate, but transverse specimens along the rolling direction were also involved. The ductility index (percentage reduction of area), impact toughness index (Charpy impact energy), and fracture toughness index (critical crack tip opening displacement (CTOD) values) all decrease as the temperature declines. All the mechanical properties and the impact and fracture toughness along the through-thickness direction are worse than those along the rolling direction. The results also offer experimental support for the determination of an evaluation indicator for structural steel thick plates with through-thickness characteristics.

The optimization of the valve plate transition region is an important way of reducing the noise emission for an axial piston pump. However, the optimized methods through simulation or experiment are actually trial and error, and they cannot indicate the precise structural parameters of the valve plate transition region. In this study, a new design method for the transition region of valve plate based on the matching of flow area and reduction of transient reverse flow was proposed, and with which a valve plate was designed. Then, the impact of the flow ripple in the discharge line of an axial piston pump and the pressure overshoot and undershoot in the piston chamber on hydraulic and structural noise for axial piston pump is discussed. The noise reduction effect of the axial piston pump with this valve plate was analyzed by adopting a flow characteristic simulation model. Finally, the results showed that the application of this design method could contribute much to the reduction of the flow ripple and elimination of the pressure overshoot and undershoot. As a consequence, the method can be used in the design of a low-noise open circuit axial piston pump.

The aerodynamic performance, structural strength, and wheel weight are three important factors in the design process of the radial turbine for micro gas turbines. This study presents the experimental validation process of this integrated optimization design method by using the similarity theory. Cold modeling tests and investigations into the aerodynamic characteristics were performed. Experimental results showed that the aerodynamic efficiency of the micro radial turbine is 84.3% at the design point while also satisfying the aerodynamic and strength requirements. Meanwhile, the total weight of the turbine wheel is 3.8 kg which has only a 52.8% mass of the original design. This indicates that the radial turbine designed through this technique has a high aerodynamic performance, and thus can be applied to micro gas turbines. The results validated that this integrated optimization design method is reliable.

The original version of this article unfortunately contained one mistake. In p.871, the data in Table 3 were incorrect. The correct version of Table 3 is given below.