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This paper presents the analyses of toppling response of layered reverse-dip slopes under the influence of geometric factors of slope angle, strata thickness and dip. The toppling response of reverse-dip slopes under different geometric factors is obtained by using the discrete element code UDEC. Then, a prediction model for toppling deformation is developed by utilizing support vector machine and the toppling-prone combinations of these geometric factors are determined from a total of 120 samples of reverse-dip slopes. The study has shown that the geometric model is a quarter of a spheroid with a slope angle of 80°, a strata dip of 80°, and a strata thickness of 0.19 m as the center. The length of the long equatorial radius of the spheroid is 31° (strata dip axial), that of the short equatorial radius is 21° (slope angle axial), and the polar radius is 0.075 m (strata thickness axial). And the ratio of long equatorial radius, short equatorial radius, and polar radius is 2.48:1.68:1.00.

We derive the formulas that describe the exact solution of the boundary value problem in the theory of elasticity for a rectangle in which two opposite (horizontal) sides are free and stresses are specified (all cases of symmetry relative to the central axes) on the other two sides (rectangle ends). The formulas for a half-strip are also given. The solutions are represented as series in Papkovich–Fadle eigenfunctions whose coefficients are determined from simple formulas. The obtained formulas remain the same for other types of homogeneous boundary conditions, for example, when the horizontal sides of the rectangle are firmly clamped, have stiffening ribs that work in tension–compression and/or bending, etc. Obviously, in this case, the Papkovich–Fadle eigenfunctions will change, as well as the corresponding biorthogonal functions and normalizing factors. To solve a specific boundary value problem, it is enough to find the Lagrange coefficients, which are determined from simple formulas, as Fourier integrals of boundary functions specified at the ends of the rectangle, and then substitute them into the necessary formulas. Examples of solving two problems (even-symmetric deformation relative to the central coordinate axes) are given: (a) The normal stresses are known at the rectangle ends, and the tangential ones are zero; and (b) the longitudinal displacements conditioned by the action of some normal stresses are known at the rectangle ends (the tangential stresses are zero). These solutions are compared with the known solutions in trigonometric Fourier series. The basis of the exact solutions obtained is the theory of expansions in Papkovich–Fadle eigenfunctions based on the Borel transform in the class of quasi-entire functions of exponential type (developed by the authors in their previous studies).

The changes of lakes directly affect the sustainable development of regional ecological environment and social economy. Affected by the environmental changes and human activities, most of the inland lakes globally have suffered from the area shrinkage and wetland degradation. The protection and restoration of lakes have become a hot public issue. In this study, a lake spatial database of Hubei Province (China) is built to analyze the temporal-spatial dynamic change of lakes in Hubei Province from 1974 to 2014, with the analysis models of lake dynamic change rate (LDCR), lake landscape shape index (LLSI), and lake centroid shift rate (LCSR). The results are as follows: (1) Lakes in Hubei Province showed a shrinking and fragmenting trend from 1975 to 2014. The total area of lakes decreased by 23.08%, and the number of lake increased by 68.03%. (2) The value of LLSI firstly increased and then decreased after 1995, meaning that the lake disturbance degree of human activities decreased firstly and then increased. (3) The lake centroids of Hubei Province were in the Jianghan Plain and shifted to the northwest by 33.67 km from 1975 to 2014, due to the lake shrinkage was more serious in the southeastern than in the northwest. The situation of inland lakes’ shrinkage and degeneration is still very severe. The national and local governments should strengthen the lake management and protection, curb the lake shrinkage and degradation, and promote the healthy and sustainable development of lakes.

To better understand the mechanism of development of lateral resistance of single drilled piles installed in improved soil profile. Side-by-side static load tests were performed on the piles installed in virgin soil profile and improved soil profile with the soil ahead of the pile cement-improved. Parametric three-dimensional finite element analyses were performed to study the effect of grouting radius. More soils at the side of piles make a critical contribution to resisting lateral loads due to the influence of improved soil ahead of the pile. A new hyperbolic p–y function that modifies the initial subgrade modulus and the ultimate lateral soil resistance is proposed based on the finite element analyses to account for the effect of the cement improvement. The proposed p–y method is capable of predicting laterally loaded pile response in cement-improved soil profiles as measured in the static load tests. The accuracy of the proposed p–y model is appropriate as shown by comparing measured and calculated the lateral behaviour of the single pile.

We propose a method of solving mixed boundary value problems in the theory of elasticity in an infinite horizontal strip that has two points of change in the type of boundary conditions located on the upper and lower sides of the strip and lying at the ends of a vertical segment—the line of the joint between the left and right half-strips. The solutions to the right and the left of the joint line are represented as series in eigenfunctions that correspond to particular boundary conditions on the horizontal sides of the right and left half-strips. Solution continuity conditions or, on the contrary, discontinuities of the displacements or stresses can be specified at the joint between the half-strips. We illustrate the main idea of the method initially using a mixed boundary value problem for the harmonic equation as an example. Here, biorthogonal functions are constructed, their properties and the properties of the coefficients of expansions are investigated, and examples are given to illustrate the correctness of the obtained solutions. Subsequently we solve a mixed boundary value problem in which two trigonometric systems of functions with different eigenvalues are involved at the joint between the half-strips. We consider examples where (1) displacement and stress continuity conditions, (2) a discontinuity of the longitudinal displacements, and (3) a discontinuity of the transverse displacements are specified at the joint between the half-strips.

Fifteen individual perfluoroalkyl substances (PFASs) were analyzed in 22 sediment samples collected from Anqing urban lakes (Anhui province, China) by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). Total PFAS concentration was between 0.61 and 26 ng g− 1 dry weight. Perfluorooctane sulfonate (PFOS) was the dominant PFAS contaminant, with a concentration range of

Traditional assessments of water resources use water availability as an evaluating metric. Water availability is a statistical average and cannot reflect the spatial differences of water resources in a region or basin. This assessment usually engenders a paradox, that is, water resources are abundant in a region but it is difficult to obtain water for the people on some spatial points in this region. In this study we define a new term, water accessibility, to eliminate this paradox and develop a model of water accessibility (the SHRD model) to meet the need of spatial details in water resources assessment at the grid scale. In the case study the water accessibility of the Hanjiang River Basin is mapped and assessed by the SHRD model. The comprehensive index of water accessibility is 0 to 4.5 and tends to increase from northwest to southeast in the study area. The results of the SHRD model can show the spatial pattern of water accessibility in a region, and can server a more finely-tuned water resources management approach. This model and method push the macroscopic (regional) water resources assessment forward from the microcosmic (raster cell) analysis.

Using the boundary value problem on the bending of a thin elastic semi-infinite plate in which the long sides are free, while a self-balanced bending moment and a generalized shearing force are specified at its end as an example, we consider the main steps in constructing exact solutions to the boundary value problems of bending of thin elastic rectangular plates. The solutions are constructed in the form of series in Papkovich–Fadle eigenfunctions. The unknown expansion coefficients are determined in the same way as in classical periodic solutions in trigonometric series and have the same structure, i.e., are expressed via the Fourier integrals of the boundary functions specified at the half-strip end. The systems of functions biorthogonal to the Papkovich–Fadle eigenfunctions constructed here are used in this case. The exact solutions possess properties that are not inherent in any of the known solutions in the theory of plate bending. Some of them are discussed in the paper. The final formulas describing the exact solution of the boundary value problem are simple and can be easily used in engineering practice. The results that we have obtained previously when solving the boundary values problems of the plane theory of elasticity in a rectangular region form the basis for our work.

In this paper, a comprehensive analysis of spatiotemporal characteristics of reverse-dip slope toppling is conducted by taking the Xiaodongcao slope as an example. First, a spatial partitioning analysis of toppling deformation is performed based on the field reconnaissance and interpretation of engineering geological data. Then, the variations of toppling deformation in time domain are analyzed for different areas of the slope with monitored data of surface displacement. Finally, the isochrones of toppling displacement evolution are constructed by using inverse distance weighted interpolation of surface monitoring data at discrete locations. The results presented in the study have shown that: (1) the displacement at the rear of the slope is dominated by vertical deformation, whereas the horizontal deformation is predominant at the slope front which also controls the overall deformation of the bank slope; (2) the overall evolution of slope deformation is dominated by the strip area at the center of the slope. In particular, the overall deformation of the slope lags behind the central region, and the displacement in this strip area could trigger an overall displacement of the bank slope. It is thus inferred that the stripe area serves as the locked segment for the toppling deformation of the slope.

Laterally loaded piles may entail large deformation under some circumstances such as ship impact, earthquake and long-term horizontal thrust of arch bridges, etc. The arch bridges are especially sensitive to horizontal displacement of foundation. Lateral load test was performed on a full-scale pile in virgin soil and pile with post-grouted soil around pile. Further numerical simulation analysis was carried out by PLAXIS3D based on field test result. The analytical and measured results are found to be in fairly satisfactory agreement. According to test results of single pile, lateral response of piles largely depends on profile of limiting force in shallow soil. Horizontal bearing capacity of bored piles is improved via grouting technique. For pile with post-grouted soil around, horizontal displacement of pile top is significantly reduced. The maximum bending moments of pile with grouting decrease dramatically. The grouted upper soil expands range of effective soil around pile, and more horizontal thrust was shared.

A series of interesting questions will be proposed and tried to be answered in this paper such as: Is there a limit of disaster-bearing capability in a region human-environment system (HES) when the system is hit by an extreme flood disaster? If so, what does it mean and how can it be explained? An assumption, naming the regional limit of flood-bearing capability (LFBC), is suggested and proved to respond these questions in this study. The LFBC model consists of three factors, namely, the disaster-causing factor (DCF), disaster-bearing factor (DBF) and disaster-regulating factor (DRF). The DCF can be selected from the cause analysis of flood, the DBF can be extracted from analysis of flood risk and vulnerability, and the DRF is responding to the analysis of flood risk management and measures. The logical relations among the three factors are determined by the analysis of flood inundation-loss models. The limit of disaster-bearing capability in regional HES is introduced by the principles of threshold analysis in terms of large-scale system theory, and can be expressed as the regional inundated depth or the amount of water in a flood. The LFBC model is built up following this idea, and approaches of its application are stated with the support of remote sensing (RS) and geographical information system (GIS). Substantial changes in terms of system succession, such as reservoir resettlement, population migration and land use pattern change, would occur only when extreme flood beyond its limit of disaster-bearing capability in a regional HES. Otherwise, the difference can be use to measures the damage conditions. Combining the occurrence probability of extreme flood, the LFBC model could be used to provide the data support for flood damage assessment, regional disaster control and reduction countermeasures, and regional development planning.

In June 2006, samples were collected from a 90 cm snow-pit at an elevation of 5 040 m a.s.l. in the northern branch firn basin of the Glacier No. 12, Laohugou Valley, in the western part of Qilian Mountain, China. Oxygen isotopes (δ 18 O) and major soluble ions were measured. Results showed that Ca 2+ is the dominant cation, and SO4 2- is the dominant anion. All major ions have close positive correlations with eachother except NO3 - and NH4 + . δ 18 O show positive correlation with air temperature. The method of correlation analysis, sea-salt ion tracer and trend analysis were used to determine the source of the chemical components. The correlation analysis and HYSPLIT backward trajectory analysis suggest that atmospheric soluble dust species dominate the chemical signature.

The purpose of this study is to develop an assessment framework of ecological security at the watershed scale to meet the need of watershed management, and to assess ecological security using this framework in the middle and lower reaches of Hanjiang River Basin (in Hubei Province, China). The states and their changes of ecological security in the study region are investigated with the support of ERDAS and ARC/INFO platform. The results show that the ecological security index (P) values in 1995 and 2000 were 0.685 and 0.699 respectively in the study region. While in 2005 and 2010, the P values were decreased to 0.657 and 0.624. In 1995, there were 5 counties with degree II state (the poor state) of ecological security, and 14 counties with degree III state (the common state). By 2000, the amount of counties with degree II decreased to 4 counties. And the number of counties with degree II is the same as 2000 in 2005. The result of 2010 shows there were 12 countries with degree III state as well as 7 counties with degree II state. The results of our case study of the Hanjiang River Basin reflect that the ES situation is very grim in the study area. The degree of ecological security developed in this study can be used as a useful tool for watershed managers and decision-makers.

A fast-settling all-digital phase-locked loop (ADPLL) is presented in this paper. We propose two techniques for reducing the settling time of an ADPLL, i.e. the oscillator tuning word (OTW) presetting technique and counter-based mode switching controller (CB-MSC). In the first technique, the OTW is preset in process, voltage, and temperature (PVT) calibration mode (P-mode), which leads to the digitally controlled oscillator being initialized with a frequency closer to the target. In the second technique, the CB-MSC is used to shorten the mode switching time. A prototype 1.9 GHz ADPLL with a 13 MHz reference is implemented in 0.18 μm CMOS process. Measurements show that the proposed techniques reduce the settling time by about 33 %. The proposed ADPLL settles within 130 reference cycles and presents a phase noise of ?116 dBc/[email protected] MHz.

This paper introduces the statistical methods and application for the quantitative analysis of a site-specific landslide risk on the north slope of Lishan Mountain which is regarded being in an active state that could become a disastrous loess landslide. Based on the theory of probability statistics (Monte Carlo statistical methods) and the slope failure mechanical model, the overall failure probability and the local failure probabilities of the Lishan landslide were calculated. The results of the failure probability and stability analysis showed that the northern slope of Lishan Mountain is highly prone to lose stability during seasonal intense rainfall, whereas it is stable but still exhibits failure probability under arid conditions. The analysis of the safety margin and local failure probability evidenced that the upper part of the slope is less stable than the lower part. Under the intense rainfall condition, the local failure probability and hazard of local unstable failure of the slope will increase. According to the calculation results, it is deduced that the landslide on the north of Lishan Mountain will be a gradual process evolving from the local slope failure to an overall unstable failure.

Time-to-Digital Converter (TDC) is a key block used as the phase/frequency detector in an All-Digital Phase-Locked Loop (ADPLL). Usually, it occupies a large proportion of ADPLL’s total power consumption up to about 30% to 40%. In this paper, the detailed power consumption of different components in the TDC is analyzed. A Power Management Block (PMB) is presented for the TDC to reduce its power consumption. A 24-bits TDC core with the proposed PMB is implemented in HJTC 0.18 μm CMOS technology. Simulation results show that up to 84% power reduction is achieved using our proposed technique.

In this paper, the effect of cyclic loading on drained residual strength of over-consolidated silty clay is examined based on the results from ring shear tests which were conducted with a sophisticated ring shear apparatus. Initially sheared to form shear zones under different pre-consolidation pressures and at different shear rates (SRs), soil samples were then tested under cyclic loading. After the cyclic loading application, the samples were re-sheared while the corresponding shear strengths were measured. The results show that the effect of cyclic loading on residual strength is noticeable. The effect is related to pre-consolidation history and SR of the soil samples. Under conditions of relatively low over-consolidation ratio (OCR), the soil samples show an increase in residual strength with decreasing SR after cyclic loading. Most of the peak strength values after cyclic loading are higher than the residual strength values obtained before cyclic loading. Two effects of cyclic loading on the residual strength are identified: (a) If OCR is less than or equal to 3.0, the residual strengths measured after cyclic loading are larger than those before cyclic loading; (b) If OCR is greater than or equal to 3.5, the residual strengths after cyclic loading tend to become lower than those in the shear tests before cyclic loading.

By employing a complete observation system, the underground erosion in a typical large-scale crystalline schist landslide in Japan, the Zentoku landslide, was studied. It was found that the seasonal heavy rainfall is the main factor leading to the massive underground erosion. Two types of sediment discharge of the landslide were defined. Monitored data indicated that the movement of Zentoku landslide could be affected by the underground erosion following the concentrated heavy rainfall. The influence of the underground erosion on the movement of the landslide presents different features. For the sliding block of shallow and medium depth shear zones (5–20 m), the influence of the underground erosion is most outstanding, while it is negligible for the sliding block of thick soil and rock layers (>30 m). Finally, the rainfall thresholds for the Zentoku landslide, which concern the groundwater state, underground erosion and movement of sliding blocks, were provided to further establish the warning and evacuation system.

A new damage-locating method for bridges subjected to a moving load is presented, and a new ‘moving load damage-locating indicator’ (MLDI) is introduced. A vehicle is modeled as a moving load, the bridge is simplified as an Euler-Bernoulli beam, and the damage is simulated by a reduction of stiffness properties of the elements. The curvature and MLDI values at each node of the baseline model (undamaged) and the damage model are computed respectively. Then the damage or damages can be located from a sudden change of the MLDI value. The feasibility and effectiveness of the proposed method are validated by numerical simulation. The results indicate that the method is effective, being able to not only locate a single damage accurately, but also locate multiple damages in simply-supported bridges, including multiple damages in continuous bridges. The results also indicate that the MLDI can accurately locate damages under 5% measurement noise.