Search Results (12)

To address the challenge of simulating force–thermal environmental loads on morphing wings during flight, this study proposes and validates a force–thermal simulation method based on servo loading. First, the aerodynamic loads on a multi-stage telescopic wing under extreme conditions were systematically analyzed to identify the critical design loads. Subsequently, a force–thermal servo loading platform for multi-stage telescopic wings was designed and constructed to evaluate the performance of the wing’s morphing mechanism during flight. A dynamic multi-point equivalent method based on grid reconstruction was proposed and theoretically derived, along with simulations using a traditional multi-point load distribution method. Compared to the conventional equal-area division method, the simulation results demonstrated a significant improvement in deformation fitting accuracy using the proposed method. Finally, force–thermal servo loading experiments were conducted on a prototype of the multi-stage telescopic wing. The results verified that the proposed loading method can accurately simulate load variations during flight, with experimental trends closely aligning with simulation predictions. Additionally, the experiments demonstrated the loading system’s rapid response capability, confirming the feasibility and potential of the designed loading platform and theoretical model. This research provides critical technical support and theoretical foundations for the design, validation, and force–thermal environment simulation of future multidimensional morphing wings. Full article

Previous studies have shown that over-wet soil is challenging to compact and exhibits large creep deformation. The consolidation test of small specimens cannot accurately reflect the compression law, and creep is underestimated owing to size effects, which affects the engineering quality. In order to accurately analyze the compression process of over-wet soil and establish its settlement calculation method, this study focuses on over-wet soil in Anhui Province, China, and uses a large-sized tester to load and analyze its compression law. The thermogravimetric analysis method was employed to investigate the changes in water with different binding forces during the compression process, and the settlement calculation method for over-wet soil was explored. The results show that the creep of over-wet soil is large and long-lasting, and the three-stage consolidation division method based on the $d-t$ curve is more effective in analyzing its regularity. The creep of over-wet soil is directly proportional to its water content. When the load exceeds the pre-consolidation pressure, the creep deformation becomes more significant, accounting for about 60% of the deformation under a single level load. It is recommended to use the creep coefficient ($\lambda$) for calculation. The results of the thermogravimetric analysis indicate that during the primary consolidation stage, free water is discharged, and weakly bound water is mainly discharged during the third consolidation stage, which is the main cause of creep. Finally, based on the relationship between the creep strain and water content of large samples, a calculation method for the settlement of over-wet soil foundations based on the layered summation method was established, which had a higher prediction accuracy than the conventional layered summation method. The results of this study will help clarify the deformation process and principle of over-wet soil and improve the quality of engineering. Full article

The microscopic pore throat structure of shale reservoir rocks directly affects the reservoir seepage capacity. The occurrence and flow channels of shale gas are mainly micron–nanometer pore throats. Therefore, to clarify the microstructural characteristics and influencing factors of the deep organic-rich shales, a study is conducted on the marine shale from the Upper Silurian to Lower Ordovician Wufeng–Longmaxi Formation in the southern Sichuan Basin. Petrographic lithofacies division is carried out in combination with petro-mineralogical characteristics, and a high-resolution scanning electron microscope, low-temperature nitrogen and low-temperature carbon dioxide adsorption, and micron-computed tomography are used to characterize the mineral composition and pore structure qualitatively and quantitatively, upon which the influencing factors of the microstructure are further analyzed. The results show that with the increase in burial depth, the total organic carbon content and siliceous mineral content decrease in the Wufeng formation to Long-1₁ subsection deep shale, while clay mineral content increases, which corresponds to the change in sedimentary environment from anoxic to oxidizing environment. Unexpectedly, the total pore volume of deep shale does not decrease with the increase in burial depth but increases first and then decreases. Using total organic carbon (TOC), siliceous mineral content showed a good correlation with total pore volume and specific surface area, with correlation coefficients greater than 0.7, confirming the predominant role of these two factors in controlling the pore structure of deep shales. This is mainly because the Longmaxi shale is already in the late diagenetic stage, and organic matter pores are generated in large quantities. Clay minerals have a negative correlation with the total pore volume of shale, and the correlation coefficient is 0.7591. It could be that clay minerals are much more flexible and are easily deformed to block the pores under compaction. In addition, the longitudinal heterogeneity of the deep shale reservoir structure in southern Sichuan is also controlled by the thermal effect of the Emei mantle plume on hydrocarbon generation of organic matter and the development of natural microfractures promoted by multistage tectonic movement. Overall, the complex microstructure in the deep shales of the Longmaxi Formation in the southern Sichuan Basin is jointly controlled by multiple effects, and the results of this research provide strong support for the benefit development of deep shale gas in southern Sichuan Basin. Full article

Expansive soil is prone to shrinkage and cracking during the drying process, leading to strength and permeability problems that exist widely in water conservancy projects and geotechnical engineering, including foundation pits and cracks at the bottom of channels and slopes. Such problems are closely related to the tensile strength of the soil. In this study, Nanyang expansive soil is taken as the research object and radial splitting tests were performed using a particle image velocimetry (PIV) test system on both undisturbed and remolded expansive soil during the drying process. The results indicated that the load–displacement curve of the undisturbed and remolded expansive soil specimens showed a strain-softening phenomenon and that the peak load increased with decreasing water content. Under the same other conditions, the peak load of the remolded expansive soil specimen was higher than that of the undisturbed soil specimen, with the undisturbed soil specimen having distinctive structural and fractural features. The load–displacement relation curve, displacement vector field, and fracture characteristics had an obvious one-to-one correspondence in the stage division. The compression deformation stage, crack development stage after the peak value, crack maturity stage, and failure stage could be observed via the PIV technique. Moreover, the fracture characteristics of the remolded specimens were more regular than those of the undisturbed specimens. The above research results provide a scientific basis for the design and construction of geotechnical engineering related to expansive soil. Full article

Establishing the relationship between the deformation of coal samples and acoustic emission response is the basis for the deformation prediction of coal samples. Using a combination of laboratory tests and theoretical analysis, acoustic emission tests of the uniaxial loading process were conducted on coal samples in the study area and the test results were analyzed, focusing on the rule of variation of acoustic emission counts with loading time. Based on the analysis of stress, strain, time, and acoustic-emission parameters variation, the relationship between the deformation of coal samples and acoustic emission response was established and analyzed. The analysis results show that during the loading process, the acoustic emission counts show the characteristics of stage changes, which can be divided into three stages: the initial stage with sporadic acoustic emission events, the middle stage with a stable increase of acoustic emission events, and the final stage with the rapid increase of acoustic emission events. This stage division has good consistency with the deformation stages of coal samples. Moreover, the acoustic emission counts have obvious and easily identifiable characteristics of changes in the deformation process of coal samples. The acoustic emission count can be used as a sensitive indicator in this study area to predict the deformation of coal samples. It provides a reference for the application of acoustic-emission prediction technology in this study area, which is important to improve the accuracy of geohazard prediction. Full article

In this review, we discuss various methods of reproducing life dynamics using a constructive approach. An increase in the structural complexity of a model protocell is accompanied by an increase in the stage of reproduction of a compartment (giant vesicle; GV) from simple reproduction to linked reproduction with the replication of information molecules (DNA), and eventually to recursive proliferation of a model protocell. An encounter between a plural protic catalyst (C) and DNA within a GV membrane containing a plural cationic lipid (V) spontaneously forms a supramolecular catalyst (C@DNA) that catalyzes the production of cationic membrane lipid V. The local formation of V causes budding deformation of the GV and equivolume divisions. The length of the DNA strand influences the frequency of proliferation, associated with the emergence of a primitive information flow that induces phenotypic plasticity in response to environmental conditions. A predominant protocell appears from the competitive proliferation of protocells containing DNA with different strand lengths, leading to an evolvable model protocell. Recently, peptides of amino acid thioesters have been used to construct peptide droplets through liquid–liquid phase separation. These droplets grew, owing to the supply of nutrients, and were divided repeatedly under a physical stimulus. This proposed chemical system demonstrates a new perspective of the origins of membraneless protocells, i.e., the “droplet world” hypothesis. Proliferative model protocells can be regarded as autonomous supramolecular machines. This concept of this review may open new horizons of “evolution” for intelligent supramolecular machines and robotics. Full article

It is generally accepted that during the Mesozoic NE−NNE-trending folds overprinted E−W-trending folds to form the Longshan dome in the central South China continent, although the interference map does not tell the relative ages of the fold sets. In an effort to deepen our understanding of the process of reworking the continent, paleostress analysis using calcite twins was carried out in this study to verify or falsify this model. Ten limestone samples were collected from Upper-Paleozoic limestones on the flanks of the dome and were measured using the universal stage for calcite e-twins. E-twins in the samples are divisible into two kinds, thick (≥1 μm) and thin (<1 μm), indicative of relatively higher and lower deformation temperatures, respectively. Stress estimates obtained using the improved version of Shan et al.’s (2019) method were grouped into two layer-parallel shortening (LPS) subsets and three non-LPS subsets. These subsets comprise four tectonic regimes: NWW−SEE compression (LPS1 and non-LPS1), NNE−SSW compression (LPS2 and non-LPS2), NW−SE extension (non-LPS3a) and NNE−SSW extension (non-LPS3b). They were further arranged in a temperature-decreasing order to establish a complex deformation sequence of the study area. In the sequence NE−NNE-trending folds have an older age than E−W-trending folds, something different from the model. The approximately N−S regional compression responsible for the former folds should have a profound effect on the intensely deformed continent, something ignored in earlier work. Full article

The cumulative displacement-time curve is the most common and direct method used to predict the deformation trends of landslides and divide the deformation stages. A new method based on the inverse logistic function considering inverse distance weighting (IDW) is proposed to predict the displacement of landslides, and the quantitative standards of dividing the deformation stages and determining the critical sliding time are put forward. The proposed method is applied in some landslide cases according to the displacement monitoring data and shows that the new method is effective. Moreover, long-term displacement predictions are applied in two landslides. Finally, summarized with the application in other landslide cases, the value of displacement acceleration, 0.9 mm/day², is suggested as the first early warning standard of sliding, and the fitting function of the acceleration rate with the volume or length of landslide can be considered the secondary critical threshold function of landslide failure. Full article

This paper presents the results of the development of a technology for manufacturing electro-optical Mach–Zehnder modulators based on InP. The key features of the technology are the use of one SiN_x double-patterned dielectric mask with two sequential inductively coupled plasma (ICP) etchings of the heterostructure for the simultaneous formation of active and passive sections of the modulator’s optical waveguides. This prevents misalignment errors at the borders. The planarization of the wafer surface was performed using photosensitive benzocyclobutene (BCB) films in a combined scheme. Windows in the BCB film to the bottom ohmic contact and at the die boundaries were formed by lithography, and then the excess thickness of the BCB film was removed by ICP etching until the p-InGaAs contact regions of the p-i-n heterostructure were exposed. The deposition and annealing of the top ohmic contact Ti/Pt/Au (50/25/400 nm) to p-InGaAs was carried out after the surface planarization, with the absence of both deformation and cracking of the planarizing film. A new approach to the division of the wafers into single dies is presented in this paper. The division was carried out in two stages: first, grooves were formed by dicing or deep wet etching, and then cleaving was performed along the formed grooves. The advantages of these techniques are that it allows the edges of the waveguides at the optical input/outputs to be formed and the antireflection coating to be deposited simultaneously on all dies on the wafer, before it is divided. Full article

The occurrence and migration of groundwater is a key natural factor that directly affects the stability of landslides, and rainfall has a large effect on the groundwater level in soil landslides. This study used the Baijiabao landslide in the Three Georges area of China as the research subject and used a combination of more than seven years of rainfall and GPS (Global Positioning System) monitoring data from 2007 to 2013. We applied the K-means clustering method to classify one cycle of the evolution stage into three classes based on the relative displacement of the main sliding surface of the landslide. To illustrate the relationship between the three landslide evolution divisions and the dynamic indicators, we identified rainfall factors that correspond to the actual change in the landslide using the minimal description length principle method. Based on the relationship between the actual deformation stage of the landslide and the rainfall factor from historical monitoring, the mean absolute error of the dynamic exponential smoothing model was 0.053, and the correlation coefficient was 0.929. The size of the smoothness index could be modified in real-time to achieve dynamic correction, which indicates that the model exhibited high reliability and confirmed the usefulness of the proposed model for forecasting groundwater level changes based on deep-seated soil landslide type. Full article

Rock is a complicated material which includes randomly distributed grains and cracks. The reliability of rocks under fatigue load is very important during the construction and operation of rock engineering. In this paper, we studied the deformation and failure process of red sandstone under fatigue load in a laboratory based on a new division method of strain energy types. The traditional elastic strain energy density is divided into two categories: grain strain energy density and crack strain energy density. We find that the proportion of the grain strain energy density to total strain energy density can be used as an indicator of rock yield and the proportion of the crack strain energy density to total strain energy density can be used as an indicator of rock failure. Subsequently, through extensive literature research, we found that such a phenomenon is widespread. We also find the proportion of grain strain energy density to total strain energy density when yielding is affected by rock types and elastic modulus. The proportion of crack strain energy density to total strain energy density in the pre-peak stage is stable and not affected by rock types and elastic modulus, which is about 0.04~0.13. These findings should be very helpful for rock stable state judging in rock engineering. Full article

Glacitectonic deformation in the Upper Weichselian led to the tectonic framework of large-scale folds and displaced thrust sheets of Maastrichtian (Upper Cretaceous) chalk and Pleistocene glacial deposits in the southwestern Baltic Sea region. They form surface expressions of sub-parallel ridges and elongated valleys in between and on the Jasmund Peninsula. Geomorphological mapping and detailed landform analyses give another insight into the arrangement and the formation history of these proglacial surface structures. Light detection and ranging (LiDAR) digital elevation models (DEM) analysis techniques were applied to a proglacial rather than a subglacial environment. Results suggest a division into a northern part with morphological ridges striking NW–SE and a southern part with SW–NE trending ridges. The observation of partly truncated northerly ridges and their superimposition by the southern sub-complex suggest that the northern part was generated earlier than the southern part. The applied spatial analyses tools were used to develop a new, self-consistent genetic model integrating all parts of the 100 km² large Jasmund Glacitectonic Complex. Results suggest a more consistent terminology for the tectonic setting and a revised genetic model for Jasmund, including three evolutional stages that are characterized by different ice flow patterns. Full article