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In order to analyze the adverse effect of flood affection on slope stability, the analytical expressions of buoyancy force and capillary force, hydrodynamic pressure and impact force, and scour erosion were proposed based on the aging characteristics of soil shear strength and limit equilibrium theory. According to the load combination and flood action, shear failure occurs preferentially at the foot of slope. Then, the plastic zone continues to extend upward to produce traction landslide disaster mode. Furthermore, the power function relation between shear strength index and time was established. The nonlinear accelerated creep model was also obtained. At the same time, the safety factor formula for flood loading effect slope aging stability, the time-varying characteristic value of anchor force and the compensation value of anchor force were also obtained and used to research sliding mechanism. In addition, the numerical calculation example shows that the slope safety factor decreases by more than 20 % considering the effect of flood ascending scour and impact, and the compensation value of anchorage force increases obviously with time increasing. Simultaneously, the change rate of compensation value of anchorage force increases nonlinearly with the increase of design safety factor.

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Innovative designs such as morphing wings and terrain adaptive landing systems are examples of biomimicry and innovations inspired by nature, which are actively being investigated by aerospace designers. Morphing wing designs based on Variable Geometry Truss Manipulators (VGTMs) and articulated helicopter robotic landing gear (RLG) have drawn a great deal of attention from industry. Compliant mechanisms have become increasingly popular due to their advantages over conventional rigid-body systems, and the research team led by the second author at Toronto Metropolitan University (TMU) has set their long-term goal to be exploiting these systems in the above aerospace applications. To gain a deeper insight into the design and optimization of compliant mechanisms and their potential application as alternatives to VGTM and RLG systems, this study conducted a thorough analysis of the design of flexible hinges, and single-, four-, and multi-bar configurations as a part of more complex, flexible mechanisms. The investigation highlighted the flexibility and compliance of mechanisms incorporating circular flexure hinges (CFHs), showcasing their capacity to withstand forces and moments. Despite a discrepancy between the results obtained from previously published Pseudo-Rigid-Body Model (PRBM) equations and FEM-based analyses, the mechanisms exhibited predictable linear behavior and acceptable fatigue testing results, affirming their suitability for diverse applications. While including additional linkages perpendicular to the applied force direction in a compliant mechanism with N vertical linkages led to improved factors of safety, the associated increase in system weight necessitates careful consideration. It is shown herein that, in this case, adding one vertical bar increased the safety factor by 100N percent. The present study also addressed solutions for the precise modeling of CFHs through the derivation of an empirical polynomial torsional stiffness/compliance equation related to geometric dimensions and material properties. The effectiveness of the presented empirical polynomial compliance equation was validated against FEA results, revealing a generally accurate prediction with an average error of 1.74%. It is expected that the present investigation will open new avenues to higher precision in the design of CFHs, ensuring reliability and efficiency in various practical applications, and enhancing the optimization design of compliant mechanisms comprised of such hinges. A specific focus was put on ABS plastic and aluminum alloy 7075, as they are the materials of choice for non-load-bearing and load-bearing structural components, respectively.

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In general, the design of a safe and rational laneway support scheme signifies a crucial prerequisite for ensuring the security and efficiency of mining exploitation in mines. Nevertheless, the conventional empirical support system for mining laneways faces challenges in assessing the rationality of support methods, which can compromise the safety and reliability of the laneways. To address this issue, the safety factor was incorporated into research on laneway support, and a safety evaluation method for laneway support in line with the safety factor was established. In light of the data from a specific iron mine laneway in central China, the CRITIC method was employed to preprocess the sample data. Going one step further, a Bayesian algorithm was utilized to optimize the hyperparameters of the CatBoost model, followed by proposing a prediction model based on the BO-CatBoost model for evaluating laneway safety factors of plain shotcrete support. Furthermore, the performance indexes, such as the root mean square error (RMSE), the mean absolute error (MAE), the correlation coefficient (R2), the variance accounts for (VAF), and the a-20 index, were determined to examine the predictive performance of each proposed model. In contrast to the other models, the BO-CatBoost model demonstrated the optimal predictive output item for safety factors with the lowest RMSE and MAE, the largest R2 and VAF, and an appropriate a-20 index value of 0.5688, 0.4074, 0.9553, 95.25%, and 0.9167 in the test set, respectively. Therefore, the BO-CatBoost model was proven to be the most appropriate machine learning method that can more accurately predict the safety factor, which will provide a novel approach for optimizing laneway support design and laneway safety evaluation.

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Empirical data relating body mass to immune defence against infections remain limited. Although the metabolic theory of ecology predicts that larger organisms would have weaker immune responses, recent studies have suggested that the opposite may be true. These discoveries have led to the safety factor hypothesis, which proposes that larger organisms have evolved stronger immune defences because they carry greater risks of exposure to pathogens and parasites. In this study, we simulated sepsis by exposing blood from nine primate species to a bacterial lipopolysaccharide (LPS), measured the relative expression of immune and other genes using RNAseq, and fitted phylogenetic models to determine how gene expression was related to body mass. In contrast to non-immune-annotated genes, we discovered hypermetric scaling in the LPS-induced expression of innate immune genes, such that large primates had a disproportionately greater increase in gene expression of immune genes compared to small primates. Hypermetric immune gene expression appears to support the safety factor hypothesis, though this pattern may represent a balanced evolutionary mechanism to compensate for lower per-transcript immunological effectiveness. This study contributes to the growing body of immune allometry research, highlighting its importance in understanding the complex interplay between body size and immunity over evolutionary timescales.

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Fragility fractures, which are more prevalent in women, may be significantly influenced by autophagy due to altered bone turnover. As an essential mediator of autophagy, Beclin-1 modulates bone homeostasis by regulating osteoclast and chondrocyte differentiation, however, the alteration in the local bone mechanical environment in female Beclin-1+/- mice remains unclear. In this study, our aim is to investigate the biomechanical behavior of femurs from seven-month-old female wild-type (WT) and Beclin-1+/- mice under peak physiological load, using finite element analysis on micro-CT images. Micro-CT imaging analyses revealed femoral cortical thickening in Beclin-1+/- female mice compared to WT. Three-point bending test demonstrated a 63.94% increase in whole-bone strength and a 61.18% increase in stiffness for female Beclin-1+/- murine femurs, indicating improved biomechanical integrity. After conducting finite element analysis, Beclin-1+/- mice exhibited a 26.99% reduction in von Mises stress and a 31.62% reduction in maximum principal strain in the femoral midshaft, as well as a 36.64% decrease of von Mises stress in the distal femurs, compared to WT mice. Subsequently, the strength-safety factor was determined using an empirical formula, revealing that Beclin-1+/- mice exhibited significantly higher minimum safety factors in both the midshaft and distal regions compared to WT mice. In summary, considering the increased response of bone adaptation to mechanical loading in female Beclin-1+/- mice, our findings indicate that increasing cortical bone thickness significantly improves bone biomechanical behavior by effectively reducing stress and strain within the femoral shaft.

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The seismic deterioration effects of anchor cables and slope structural planes are often neglected in the dynamic stability analysis of anchored rocky slopes to the extent that the stability of slopes is overestimated. In this paper, a dynamic calculation method for anchored rocky slopes considering the seismic deterioration effect is established, and a stability evaluation method for anchored rocky slopes based on the Gaussian mixture model is proposed. The seismic deterioration effect on the stability of anchored rocky slopes is quantitatively analyzed with an engineering example, and the relationship between seismic intensity and the failure probability of slopes is clarified. The results show that compared with the calculation method without considering the seismic deterioration effect, the minimum safety factor and post-earthquake safety factor obtained by the proposed method in this paper are smaller. The number of seismic deteriorations of the slope is used as the number of components of the Gaussian mixture model to construct the failure probability model of the slope, which can accurately predict the failure probability of anchored rocky slopes. The research results significantly improve the accuracy of the stability calculation of anchored rocky slopes, which can be used to guide the seismic design and safety assessment of anchored rocky slopes.

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Soil roadbed along the river suffers from water erosion at the bottom and collapse at the top under flood scouring, which leads to the suspension of upper pavement slab. In order to ensure the safety of soil roadbed along the river, this study explored the development mechanism of soil roadbed damage by flood in actual cases, and proposed the evolution process of instability under roadbed scouring. The stability law of roadbed along the river under flood scouring was analyzed, and the stability safety factor was corrected to analyze the sensitivity of water depth, flow rate, river bending angle and stability safety factor K in working conditions. The sensitivity of width and height of soil roadbed after flood scouring to water depth, flow velocity, river bending angle was investigated. Moreover, numerical simulation was carried out to determine the displacement nephogram and maximum shear stress nephogram of soil roadbed along the river under the conditions of road surface and roadbed load, vehicle loading or constant change of water depth. By comparing the above theories and engineering cases, the water damage mechanism of soil roadbed along the river was further verified.

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PURPOSE: To investigate safety and performance aspects of parallel-transmit (pTx) RF control-modes for a body coil at B 0 ≤ 3 T $$ {B}_0\le 3\mathrm{T} $$ . METHODS: Electromagnetic simulations of 11 human voxel models in cardiac imaging position were conducted for B 0 = 0.5 T $$ {B}_0=0.5\mathrm{T} $$ , 1.5 T $$ 1.5\mathrm{T} $$ and 3 T $$ 3\mathrm{T} $$ and a body coil with a configurable number of transmit channels (1, 2, 4, 8, 16). Three safety modes were considered: the 'SAR-controlled mode' (SCM), where specific absorption rate (SAR) is limited directly, a 'phase agnostic SAR-controlled mode' (PASCM), where phase information is neglected, and a 'power-controlled mode' (PCM), where the voltage amplitude for each channel is limited. For either mode, safety limits were established based on a set of 'anchor' simulations and then evaluated in 'target' simulations on previously unseen models. The comparison allowed to derive safety factors accounting for varying patient anatomies. All control modes were compared in terms of the B 1 + $$ {B}_1^{+} $$ amplitude and homogeneity they permit under their respective safety requirements. RESULTS: Large safety factors (approximately five) are needed if only one or two anchor models are investigated but they shrink with increasing number of anchors. The achievable B 1 + $$ {B}_1^{+} $$ is highest for SCM but this advantage is reduced when the safety factor is included. PCM appears to be more robust against variations of subjects. PASCM performance is mostly in between SCM and PCM. Compared to standard circularly polarized (CP) excitation, pTx offers minor B 1 + $$ {B}_1^{+} $$ improvements if local SAR limits are always enforced. CONCLUSION: PTx body coils can safely be used at B 0 ≤ 3 T $$ {B}_0\le 3\mathrm{T} $$ . Uncertainties in patient anatomy must be accounted for, however, by simulating many models.

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In order to investigate the effect of tension-compression asymmetry of propellant mechanical properties on the structural integrity of a Nitrate Ester Plasticized Polyether (NEPE) propellant grain, the unified constitutive equations under tension and compression were established, a new method for grain structural integrity assessment was proposed and the structural integrity of the NEPE propellant grain under the combined axial and transverse overloads was evaluated. The results indicate that the mechanical state of the NEPE propellant grain is in the coexistence of tension and compression under the combined axial and transverse overloads, and the tension and compression regions in the propellant grain is independent of the propellant constitutive behavior. The tension-compression asymmetry of the propellant mechanical properties has a certain impact on its mechanical response. The maximum equivalent stress and strain considering the tension-compression asymmetry falls between that obtained through the tension and compression constitutive model, and is the same as damage coefficient. The safety factor of the NEPE propellant grain considering the tension-compression asymmetry of its mechanical properties is larger than that non-considering, and the traditional method of structural integrity assessment is conservative.

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To investigate the structural effects of the mechanical heterogeneity of Hydroxyl-terminated polybutadiene (HTPB) propellant grain under ignition pressurization, a gradient finite element method was proposed to evaluate its structural integrity. The heterogeneous mechanical properties of the propellant grain were constructed and assessed. The results demonstrate that the mechanical properties of the propellant grain are spatially variable when taking into account the effect of the load. The range of variation in the mechanical properties is related to the size of the load and its effect on the mechanical properties of the propellant. Two key parameters that affect the mechanical response of the grain are the non-uniform distribution of the modulus and the damage strain threshold. An increase in the propellant modulus leads to an increase in the stress response and a decrease in the strain response of the propellant grain under ignition pressurization. Meanwhile, an increase in the damage strain threshold improves the propellant's modulus in the linear elastic stage in a disguised form. This also leads to an increase in the stress response and a decrease in the strain response when the strain response exceeds the damage strain threshold. The safety factor, based on the equivalent strain failure criterion of the grain, directly depends on both the strain response of the propellant grain and the maximum elongation of the propellant. Furthermore, the change in the safety factor of two propellant grains is primarily affected by the maximum elongation of the propellant.

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OBJECTIVE: The service status of tunnel lighting has an important impact on driving safety. Existing research mainly discussed the impact of a single evaluation indicator of lighting service status on driving safety and paid less attention to the impact of multiple evaluation indicators on driving safety. METHODS: In this research, field tests of tunnels in three speed scenarios and 52 service scenarios are completed. DIALux software was selected to simulate more intensive illuminance, which could be used to calculate U0, U1, qc, and C. Using U0, U1, qc, and C as explanatory variables, and applying the normalized visual recognition results as explained variables, ordinary least squares regression (OLS) was performed to calculate the influence weight of each explanatory variable on driving safety. RESULTS: The results show that the four independent variables occupied different weights under different working conditions. However, on the whole, U0 and U1 occupied a greater weight. The weight of C lies between qc and U0, and U1 and qc occupied the smallest weight in all scenarios. Locally, U0 was greater than U1, with the exception when the illumination attenuation value was 70%. CONCLUSIONS: The influence of the total uniformity of the road surface luminance and longitudinal uniformity of the road centerline luminance on driving safety was significantly greater than the influence of the contrast revealing coefficient and luminance contrast C on driving safety. When the luminous flux was attenuated to 70% or less and when the number of failed lamps was at least four, the lighting quality would be significantly reduced, which would substantially affect driving safety.

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To transfer toxicological findings from model systems, e.g. animals, to humans, standardized safety factors are applied to account for intra-species and inter-species variabilities. An alternative approach would be to measure and model the actual compound-specific uncertainties. This biological concept assumes that all observed toxicities depend not only on the exposure situation (environment = E), but also on the genetic (G) background of the model (G × E). As a quantitative discipline, toxicology needs to move beyond merely qualitative G × E concepts. Research programs are required that determine the major biological variabilities affecting toxicity and categorize their relative weights and contributions. In a complementary approach, detailed case studies need to explore the role of genetic backgrounds in the adverse effects of defined chemicals. In addition, current understanding of the selection and propagation of adverse outcome pathways (AOP) in different biological environments is very limited. To improve understanding, a particular focus is required on modulatory and counter-regulatory steps. For quantitative approaches to address uncertainties, the concept of "genetic" influence needs a more precise definition. What is usually meant by this term in the context of G × E are the protein functions encoded by the genes. Besides the gene sequence, the regulation of the gene expression and function should also be accounted for. The widened concept of past and present "gene expression" influences is summarized here as Ge. Also, the concept of "environment" needs some re-consideration in situations where exposure timing (Et) is pivotal: prolonged or repeated exposure to the insult (chemical, physical, life style) affects Ge. This implies that it changes the model system. The interaction of Ge with Et might be denoted as Ge × Et. We provide here general explanations and specific examples for this concept and show how it could be applied in the context of New Approach Methodologies (NAM).

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Within the framework of a circular economy, we aim to efficiently use raw materials and reduce waste generation. In this context, the longevity of biomimetic material systems can significantly contribute by providing robustness and resilience of system functionality inspired by biological models. The aim of this review is to outline various principles that can lead to an increase in robustness (e.g., safety factor, gradients, reactions to environmental changes) and resilience (e.g., redundancy, self-repair) and to illustrate the principles with meaningful examples. The study focuses on plant material systems with a high potential for transfer to biomimetic applications and on existing biomimetic material systems. Our fundamental concept is based on the functionality of the entire system as a function of time. We use functionality as a dimensionless measure of robustness and resilience to quantify the system function, allowing comparison within biological material systems and biomimetic material systems, but also between them. Together with the enclosed glossary of key terms, the review provides a comprehensive toolbox for interdisciplinary teams. Thus, allowing teams to communicate unambiguously and to draw inspiration from plant models when developing biomimetic material systems with great longevity potential.

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AbstractTerrestrial mammals span seven orders of magnitude in body size, ranging from the <2-g Etruscan pygmy shrew (Suncus etruscus) to the >3,900-kg African elephant (Loxodonta africana). Although body size profoundly affects the behavior, physiology, ecology, and evolution of species, how investment in functional immune defenses changes with body size across species is unknown. Here, we (1) developed a novel 12-point dilution curve approach to describe and compare antibacterial capacity against three bacterial species among >160 terrestrial species of mammals and (2) tested published predictions about the scaling of immune defenses. Our study focused on the safety factor hypothesis, which predicts that broad, early-acting immune defenses should scale hypermetrically with body mass. However, our three statistical approaches demonstrated that antibacterial activity in sera across mammals exhibits isometry; killing capacity did not change with body size across species. Intriguingly, this result indicates that the serum of a large mammal is less hospitable to bacteria than would be predicted by its metabolic rates. In other words, if metabolic rates underlie the rates of physiological reactions as postulated by the metabolic theory of ecology, large species should have disproportionately lower antibacterial capacity than small species, but they do not. These results have direct implications for effectively modeling the evolution of immune defenses and identifying potential reservoir hosts of pathogens.

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The purpose of this work is to propose a tier-based formalism for safety assessment of custom-built radio-frequency (RF) coils that balances validation effort with the effort put in determinating the safety factor. The formalism has three tier levels. Higher tiers require increased effort when validating electromagnetic simulation results but allow for less conservative safety factors. In addition, we propose a new method to calculate modeling uncertainty between simulations and measurements and a new method to propagate uncertainties in the simulation into a safety factor that minimizes the risk of underestimating the peak specific absorption rate (SAR). The new safety assessment procedure was completed for all tier levels for an eight-channel dipole array for prostate imaging at 7 T and an eight-channel dipole array for head imaging at 10.5 T, using data from two different research sites. For the 7 T body array, the validation procedure resulted in a modeling uncertainty of 77% between measured and simulated local SAR distributions. For a situation where RF shimming is performed on the prostate, average power limits of 2.4 and 4.5 W/channel were found for tiers 2 and 3, respectively. When the worst-case peak SAR among all phase settings was calculated, power limits of 1.4 and 2.7 W/channel were found for tiers 2 and 3, respectively. For the 10.5 T head array, a modeling uncertainty of 21% was found based on B1 + mapping. For the tier 2 validation, a power limit of 2.6 W/channel was calculated. The demonstrated tier system provides a strategy for evaluating modeling inaccuracy, allowing for the rapid translation of novel coil designs with conservative safety factors and the implementation of less conservative safety factors for frequently used coil arrays at the expense of increased validation effort.

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Uncertainty factors (UFs) are used to account for uncertainties and variability when setting exposure limits or guidance values. Starting from a proposal of a single UF of 100 to extrapolate from an animal NOAEL to a human acceptable exposure, the aspects of uncertainty and number of UFs have diversified and today there are several risk assessment guidelines that contain schemes of default UFs of varying complexity. In the present work, we scoped the scientific literature on default UFs to map developments regarding recommendations and evaluations of these. We identified 91 publications making recommendations for one or several UFs and 55 publications evaluating UFs without making explicit recommendations about numerical values; these were published between 1954 and 2021. The 2000s was the decade with the largest number of publications, interspecies differences and intraspecies variability being the most frequent topics. The academic sector has been the most active (76 out of 146 publications). Authors from the private sector more often presented UF recommendations, but differences between sectors regarding size of recommendations were not statistically significant. The empirical underpinning of the reviewed recommendations ranges from four to 462 chemicals, that is, relatively low numbers compared with the range of chemicals these default UFs are expected to cover. The recommended UFs have remained remarkably constant, with merely a slight decrease over time. Although chemical specific UFs are preferable, the widespread use of default UFs warrants further attention regarding their empirical and normative basis.

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Leachate recharging not only solves the leachate treatment problem but also has tremendous environmental and engineering benefits. In this study, a recharge model was developed based on consideration of the inhomogeneous characteristics of the pile and the degree of clogging of the leachate collection and removal system (LCRs), and a design diagram of the maximum injection pressure Ps and the minimum setback distance ds was given. The following conclusions are obtained: the rate of diffusion in the horizontal and burial depth directions depends on anisotropy coefficient A, and the rate of development of the blocked water level on the LCRs depends on the degree of blockage h1. The development rate of the region affected by the recharging is low at the beginning of the recharging and increases rapidly when the moment Tb is reached, which decreases with the injection pressure P, and the degree of blockage h1. The safety factor of slope Fs decreases at a slower rate when the anisotropy coefficient is 0 < A < 1 and 15 < A < 20, and at a faster rate when 1 < A < 15. When the LCRs is blocked, the injection pressure P and anisotropy coefficient A increase the degree of influence on the recharge efficiency and slope stability, and when the blocked water level h1 > 30 m, recharge is not recommended. This model and the vertical well design method can well simulate the recharging process and its effect on the slope stability and provide a reference for the design of vertical wells.

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Virus safety of biopharmaceuticals produced in cells of animal origin is governed by regulatory guidelines. It is ensured through raw material controls, cell substrate testing, and evaluation of the purification process for virus clearance capability. An additional control for cell lines that contain endogenous viruses is the virus safety factor (VSF) calculation, to demonstrate that the virus clearance exceeds the amount of potential endogenous virus in a dose of product. Product-specific input data (product titer, process yield, intended dose, purification process virus clearance capability, and the measured titer of endogenous virus produced by the cells) are typically used for the calculation. A wide range of relevant data was obtained from the production of monoclonal antibodies in Chinese Hamster Ovary (CHO) cells, and a sensitivity analysis was performed by using Monte Carlo simulations to determine which input data had the most significant impact on the range and distribution of the VSF. The sensitivity analysis suggested that the VSF calculation can be streamlined to include virus clearance capability, the endogenous virus titer, and dose while excluding product titer and process yield. Furthermore, the simulated VSF exceeded 4 log10 in 96% of the simulations, providing a high level of assurance of virus safety for antibodies produced in CHO cells and purified within specified operational parameters.

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Water gushing is a common engineering geological disaster in the process of foundation pit construction. Its successful judgment directly affects the safety of engineering construction. Taking the case of water gushing at the bottom of the foundation pitas as a research object, the mechanism and treatment of water gushing in foundation pits, the stability against water gushing, and its influencing factors are analyzed with a field investigation, field testing, and theoretical calculation. The calculation formula for the safety factor and critical thickness of the foundation pit against surges, considering the influence of multiple factors, is deduced. The influence of the height of the confined water level, the thickness of the water-resisting layer, the shear strength of the soil mass, the reinforcement depth of the soil mass in the pit, and the diameter of the bearing pile in the pit on the safety factor of the foundation pit surge are expounded. In addition, measures such as the reinforcement of the soil mass in the passive area in the pit, the increase in the thickness of the water-resisting layer, and the reduction in the confined water level are proposed to improve the anti-surge stability of the foundation pit. A new monitoring method is proposed for characterizing uplift deformation at the bottom of the pit without affecting normal construction. The research results show that: (1) the minimum safety factor against surges, considering multiple factors, is 1.455, and the critical thickness is 5.87 m, which is in line with specifications. (2) Measures such as reinforcing the soil in the passive zone of the pit, increasing the thickness of the water-insulating layer, and lowering the bearing pressure level are used to improve the stability of the pit against surges. (3) The pit, obtained by the pit bottom counter-pressure, pumping water out of the pit, and the timely construction of the pit bottom bedding to block the program, exhibits a measured maximum bottom plate pressure of 115.189 kPa, and the deformation corresponding to the method proposed in this paper is 1.406 mm, which is better disposed in the field. The research results provide a reference basis for the judgment of anti-surge stability of foundation pits and similar engineering applications.

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Macroalgae and seagrasses in coastal habitats are exposed to turbulent water currents and waves that deform them and can rip them off the substratum, but that also transport essential water-borne substances to them and disperse their propagules and wastes. Field studies of the physical environment, ecological interactions, and life history strategies of marine macrophytes reveal which aspects of their biomechanical performance are important to their success in different types of natural habitats and enable us to design ecologically relevant laboratory experiments to study biomechanical function. Morphology and tissue mechanical properties determine the hydrodynamic forces on macrophytes and their fate when exposed to those forces, but different mechanical designs can perform well in the same biophysical habitat. There is a trade-off between maximizing photosynthesis and minimizing breakage, and some macrophytes change their morphology in response to environmental cues. Water flow in marine habitats varies on a wide range of temporal and spatial scales, so diverse flow microhabitats can occur at the same site. Likewise, the size, shape, and tissue material properties of macrophytes change as they grow and age, so it is important to understand the different physical challenges met by macrophytes throughout their lives.

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