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Loess is usually compacted as building filler in geotechnical engineering construction and the wetting-induced deformation characteristics of compacted loess are closely related to engineering safety. The influence of hydromechanical paths on compacted loess wetting-induced deformation characteristics has been rarely addressed in the literature, especially for compacted sandy loess. In this study, the scanning electron microscopy (SEM) and soil–water retention curve (SWRC) tests are performed to investigate the microstructure and water retention characteristics of compacted sandy loess. Single-oedometer triaxial wetting tests with three complex hydromechanical paths (consolidation-wetting under isotropic stress state, consolidation-loading-wetting-loading and consolidation-unloading-wetting-unloading under deviator stress) are carried out on unsaturated compacted sandy loess. Results indicate that: (1) As the dry density increases, the large inter-aggregate pores inside the compacted sandy loess turned into medium inter-aggregate pores and small inter-aggregate pores; the air entry value increases and the water retention capacity is enhanced. (2) Within a certain range of confining pressure (no more than 400 kPa), the wetting volumetric strain increases with the increase in confining pressure and dry density under isotropic stress condition; the loading paths wetting-induced deformation is greater than unloading paths wetting-induced deformation under deviator stress condition. (3) At a lower stress ratio, compacted sandy loess undergoes significant wetting-induced dilatancy; the wetting-induced deformation under the unloading path appears significant, compared with that under the loading path. [ABSTRACT FROM AUTHOR]

Focusing mainly on the compressive-shear (C-S) stress, the existing soil strength theories fail to well describe the soil strength under tenso–shear (T-S) stress and are not suitable for analyzing the tensile strength and T-S coupling strength. Taking the T-S strength into account, a three-dimensional nonlinear strength model of soil is established. The failure function on the π plane is a Lade Lade-curved triangle in principal stress space, which reasonably reflects the effect of medium principal stress. The failure function on the triaxial compression meridian plane is divided into the T-S and C-S zones, in which the two failure functions are smoothly connected at the closed stress point. To easily combine it with the specific elastoplastic constitutive theory, the proposed strength model is transformed into the D-P criterion in transformed stress space using the transformation stress method, which provides a theoretical foundation for numerical calculations. Compared with the true triaxial test results and numerical slope examples, the proposed model gives a good description of the nonlinear soil strength under complex stresses and the instability failure mechanism of the slope. [ABSTRACT FROM AUTHOR]

In actual work, the system parameters of the robot joints will change in real time or cannot be measured, and the coupling relationship between the various subsystems and the existence of modeling errors make the system model difficult to determine. Based on such problems, a neural network observation is proposed Decentralized control method for robot joints of the robot. In the actual control of the manipulator, firstly, the model of each joint subsystem is established by the decentralized control theory, and the nonlinear function approximation ability of the neural network is used to approach the uncertain part of the manipulator subsystem online through input and output data. The design observer can estimate the state of the system, and use the estimated state to design a sliding mode controller to dynamically estimate and compensate the unknown model dynamics of each independent joint, and realize the self-control of the system when the speed information and model information are unknown. Adaptive control greatly enhances the robustness and adaptability of the robotic arm system. Finally, the stability criterion of the neural network observer and the sliding mode controller is given by the Lyapunov function method, and the simulation results prove the effectiveness of the design method.

This article presents a bounding surface model for unsaturated soils by using skeleton stress and bonding variable based on microcosmic pore structure as constitutive variables. A Hydraulic hysteresis soil-water characteristic curve model considering deformation and hydraulic hysteresis is combined to achieve hydraulic coupling. The proposed model can capture the change of the inter-particles bonding effect in the deformation process of unsaturated soils and accurately predict the hydraulic mechanical behavior of unsaturated soils under complicated loading paths and wetting-drying cycles. The validity of the proposed model is confirmed by the results of unsaturated isotropic compression tests, wetting-drying cycles tests and unsaturated triaxial shear tests reported in the literature.

Cell migration is a pivotal step in metastatic process, which requires cancer cells to navigate a complex spatially‐confined environment, including tracks within blood vessels and in the vasculature of target organs. Here it is shown that during spatially‐confined migration, the expression of insulin‐like growth factor‐binding protein 1 (IGFBP1) is upregulated in tumor cells. Secreted IGFBP1 inhibits AKT1‐mediated phosphorylation of mitochondrial superoxide dismutase (SOD2) serine (S) 27 and enhances SOD2 activity. Enhanced SOD2 attenuates mitochondrial reactive oxygen species (ROS) accumulation in confined cells, which supports tumor cell survival in blood vessels of lung tissues, thereby accelerating tumor metastasis in mice. The levels of blood IGFBP1 correlate with metastatic recurrence of lung cancer patients. This finding reveals a unique mechanism by which IGFBP1 sustains cell survival during confined migration by enhancing mitochondrial ROS detoxification, thereby promoting tumor metastasis. [ABSTRACT FROM AUTHOR]

This study proposes an approach to simulate the effects of initial density on the relative coefficient of permeability for unsaturated soils. The density-dependent permeability function is derived based on (i) an incremental relationship between the degree of saturation and the initial void ratio with various suctions and (ii) the relationship between the permeability function and the soil-water retention curve (SWRC). Only one additional parameter is required in the proposed function, which can be calibrated using a conventional SWRC test. A number of test results in the literature are employed to validate the proposed density-dependent permeability function, and the model predictions indicate good agreement with the experimental data in the literature. Key words: unsaturated soil, soil-water retention curve, permeability function, initial density. Cette etude propose une approche pour simuler les effets de la densite initiale sur le coefficient relatif de permeabilite pour les sols non satures. La fonction de permeabilite dependante de la densite est derivee a partir de (i) une relation incrementale entre le degre de saturation et l'indice des vides initial a diverses succions, et (ii) la relation entre la fonction de permeabilite et la courbe de retention d'eau (CRE). Un seul parametre additionnel est necessaire dans la fonction proposee, qui peut etre calibre avec un essai de CRE conventionnel. Plusieurs resultats d'essais provenant de la litterature ont ete utilises pour valider la fonction de permeabilite dependante de la densite proposee, et les predictions du modele indiquent une bonne correspondance avec les donnees experimentales de la litterature. [Traduit par la Redaction] Mots-cles: sol non sature, courbe de retention d'eau du sol, fonction de permeabilite, densite initiale., Introduction The coefficient of permeability (or hydraulic conductivity) is one of the inevitable parameters to determine the hydraulic property of soils. For a soil, the coefficient of permeability (k) is [...]

North China Plain is the largest agricultural production center in China and wheat-maize rotation is a widespread cultivation practice in this area. As gross primary production (GPP) is a proxy of land productivity, research on its spatial-temporal dynamics helps understand the variation of grain production in wheat-maize rotation. Here, Moderate Resolution Imaging Spectroradiometer (MODIS) data and ground observation data were combined to drive Vegetation Photosynthesis Model (VPM) in GPP estimation over wheat-maize rotation area during 2000–2015. Annual GPP has increased by 540.95 g C m−2 year−1 from 2000 to 2015, while total annual GPP has grown ∼150% than that of 2000. Moreover, annual GPP showed an increasing trend in the consecutively wheat-maize rotation area between 2000 and 2015. A strong linear relationship between GPP estimates and grain production demonstrated the potential of using VPM model to evaluate grain production in wheat-maize rotation area of Henan province, China. [ABSTRACT FROM AUTHOR]