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To conduct a sensitivity analysis of the relevant parameters that impact the mechanics of tunnel construction in karst areas, firstly, the orthogonal design and range analysis method is applied to sort the 11 kinds of karst-tunnel-influencing factors from high to low according to the sensitivity degree. Secondly, the random forest algorithm based on an orthogonal experimental design is applied to the feature importance ranking of the influencing factors of karst tunnels. Thirdly, according to the results of the sensitivity analysis, the optimum combinations of influencing factors of tunnel construction in karst areas is obtained. The research based on these two methods shows that when taking the vertical displacement as the target variable, the parameters with the highest feature importance are A6 (tunnel diameter) and A10 (tunnel buried depth). When taking the first principal stress as the target variable, the most important influencing factors are A10 (tunnel buried depth) and A9 (location of karst cave). When taking the principal stress difference as the target variable, the most important influencing factors are A10 (tunnel buried depth) and A6 (tunnel diameter). The level combination of the 11 influencing factors obtained by taking the principal stress difference as the target variable was more balanced than the vertical displacement and the principal stress difference as the target variables. The results of this study will provide a theoretical basis to study key parameters in the response of mechanical characteristics to the safe construction of tunnels in karst areas.

To conduct a sensitivity analysis of the relevant parameters that impact the mechanics of tunnel construction in karst areas, firstly, the orthogonal design and range analysis method is applied to sort the 11 kinds of karst-tunnel-influencing factors from high to low according to the sensitivity degree. Secondly, the random forest algorithm based on an orthogonal experimental design is applied to the feature importance ranking of the influencing factors of karst tunnels. Thirdly, according to the results of the sensitivity analysis, the optimum combinations of influencing factors of tunnel construction in karst areas is obtained. The research based on these two methods shows that when taking the vertical displacement as the target variable, the parameters with the highest feature importance are A6 (tunnel diameter) and A10 (tunnel buried depth). When taking the first principal stress as the target variable, the most important influencing factors are A10 (tunnel buried depth) and A9 (location of karst cave). When taking the principal stress difference as the target variable, the most important influencing factors are A10 (tunnel buried depth) and A6 (tunnel diameter). The level combination of the 11 influencing factors obtained by taking the principal stress difference as the target variable was more balanced than the vertical displacement and the principal stress difference as the target variables. The results of this study will provide a theoretical basis to study key parameters in the response of mechanical characteristics to the safe construction of tunnels in karst areas. [ABSTRACT FROM AUTHOR]

The hyporheic zone is a transition zone for the exchange of matter and energy between surface water and subsurface water. The study of trends and sensitivities of bed hyporheic exchanges to the various influencing factors is of great significance. The surface−groundwater flow process was simulated using a multiphysics computational fluid dynamics (CFD) method and compared to previous flume experiments. Based on that, the single-factor effects of flow velocity (u), water depth (H), dune wave height (h), and bed substrate permeability (κ) on hyporheic exchange in the bed hyporheic zone were investigated. The sensitivity analysis of various factors (H, u, dune wavelength (L), h, bed substrate porosity (θ), κ, and the diffusion coefficient of solute molecules (Dm)) in the surface−subsurface water coupling model was done using orthogonal tests. The results indicated that u, h, and κ were positively related, whereas H was negatively related to hyporheic exchange. H and u showed large effects, whereas κ, Dm, and θ had moderate effects, and L and h showed small effects on hyporheic exchange. This study provides valuable references for the protection and recovery of river ecology.

AbstractIn order to improve the safety of on-board hydrogen storage tanks during collision, a protective shell based on a negative Poisson’s ratio (NPR) core is designed in this paper. After analyzing and comparing the crashworthiness of three typical honeycomb structures, the concave hexagonal negative Poisson’s ratio honeycomb is selected as the energy-absorbing inner core of the hydrogen storage tank protection structure. The sensitivity analysis of the structural parameters of the NPR shell is conducted through orthogonal tests to identify parameters with a significant impact on crash performance. These parameters are then used as experimental variables for subsequent optimization design. Subsequently, a response surface approximation model between the optimization objective and the structural parameters is established based on the response surface method. Finally, the adaptive simulated annealing algorithm (ASA), neighborhood cultivation genetic algorithm (NCGA), and non-dominated sorting genetic algorithm-II (NSGA-II) are used to optimize the structural parameters, and the optimization results are verified by the whole-vehicle crash simulation. The simulation results demonstrate that all three algorithms achieve better optimization results, among which NCGA is more advantageous in improving the overall performance of the protective shell. After NCGA optimization, the specific energy absorption of the protective shell increases by 19.75%, the maximum collision force of the rigid wall decreases by 23.63%, and the maximum stress of the hydrogen storage tank body decreases by 22.77%. These findings indicate that the designed protection shell effectively improves the crashworthiness of the hydrogen storage tank during collisions. [ABSTRACT FROM AUTHOR]

Currently, studies on Xinjiang desert water conveyance channels primarily focus on the selection of construction technologies, with the effects of bank slope reinforcement and the impact of internal and external factors on slope stability remaining unclear. This study utilizes finite element method to analyze the safety coefficient, overall displacement, and equivalent plastic zone of aeolian soil bank slopes before and after reinforcement during three distinct phases: the completion phase, the water transfer phase, and the water level plunge phase. Orthogonal tests were used to assess the trend and weighting of the influence of factors on bank slopes inside and outside the channel using the introduction of corrected range and Spearman correlation analysis. The findings indicate that the safety coefficient for the bank slopes of the desert channel both before and after reinforcement exceeds 1.30 during all phases. Post-reinforcement, the overall displacement and equivalent plastic zone are controlled compared to the pre-reinforced state. Both sensitivity analyses yielded that the factors affecting the weighting of bank slopes were, in descending order, aeolian soil cohesion > slope angle > angle of internal friction > slope height > unit-weight > thickness of concrete lining > height of the water level in the channel > rate of water level plunge; where aeolian soil cohesion, slope angle, angle of internal friction and thickness of concrete lining favoured the stability of the bank slopes, while others were unfavourable to the stability of the bank slopes. This study aims to provide a reference for the construction of desert water supply projects. [ABSTRACT FROM AUTHOR]

With the development of infrastructure construction, an increasing number of projects are faced with the problem of hydraulic and dynamic coupling. However, traditional physical model materials mainly consider the single factor influence and lack comprehensive research on the hydraulic and dynamic parameters of similar materials. Based on the dimensionless criterion and Buckingham π theorem, the dimension and similarity relation of physical model tests of rock masses under seepage and dynamic coupling are derived. A new type of similar material considering hydraulic and dynamic properties was developed by using quartz sand, barite powder, cement, water glass, rosin, and glycerol as raw materials through a large number of orthogonal tests. Meanwhile, the sensitivity analysis of the physical and mechanical properties of similar materials was carried out and the influence of each component factor on the physical properties was revealed. A material preparation scheme was developed to meet the physical and hydraulic characteristics of different rock and soil physical models. An empirical matching formula considering each parameter is proposed. This work can provide an important reference for physical model tests of similar rock masses. [ABSTRACT FROM AUTHOR]

In order to study the influence of microscopic parameters on the macroscopic mechanical response of sand, the discrete element software PFC3D is used to establish the numerical model of the triaxial test of sand in this paper, the indoor triaxial test of sand is carried out to calibrate the numerical model. The triaxial tests are finished under the conditions of confining pressures of 100 kPa, 200 kPa, 300 kPa, and 400 kPa, respectively. The influence of the microscopic parameters on the macroscopic mechanical response of the sand is analyzed, the orthogonal experimental method is used to study the sensitivity of the numerical model to microscopic parameters such as porosity, flexible boundary stiffness, normal tangential stiffness ratio, and friction coefficient. The results show that the peak strength and residual strength of the stress-strain curve of sand are most affected by the friction coefficient, they are positively correlated with the friction coefficient under different confining pressures. The normal tangential stiffness ratio is negatively correlated, it is less affected by porosity and boundary flexibility stiffness, the sensitivities of different microscopic parameters are analyzed through the orthogonal tests, the results of orthogonal tests and numerical simulations show the consistent patterns in terms of sensitivity to microscopic parameters. The results can provide the reference for the influence of microscopic parameters and the macroscopic mechanical response of sand. [Display omitted] • Microscopic parameters affect the macroscopic mechanical response of sand. • Orthogonal experiments to study the sensitivity of meso-parameters. • Analysis of variance for sensitivity of microscopic parameters. [ABSTRACT FROM AUTHOR]

Tensile strength is one of the most important mechanical parameters controlling the development of cracks in loess plateau. The unconfined penetration test (UPT) is often used as an index for prediction of soil tensile strength properties. However, suffering the influence of the experiment condition, its uncertainty and sensitivity analysis to various experiment parameters was still unknown. Therefore, this study designed orthogonal tests and conducted the sensitivity analysis of influence factors (water content, dry density, steel disk (punch) diameter, height-diameter ratio, specimen preparation method, and loading rate) on the tensile strength of loess by using UPT. The statistical analysis of the test results indicated the order that affects tensile strength of the loess was water content, disk diameter, dry density, sample preparation method, height to diameter ratio, and loading rate respectively. The tensile strength of loess presented a tendency to increase at first and afterward to decrease as the increase of the punches diameter in UPT. The tensile strength reached a maximum value for a 24.72-mm disk diameter. According to the failure mode of the specimen, 12.3 to 20.5 times height-diameter ratio punches diameter range was considered appropriate. Furthermore, in the reconstituting specimen preparation method of disturbed loess, positive and reverse static pressure method was beneficial to the gain on the tensile strength. Maintaining a 1-mm/min loading rate, the variance of tensile strength was optimal. Moreover, the interactions of factors had significant effects on the tensile strength in UPT. The achieved results can provide the references and analytical analysis for standardizing UPT to measure the loess tensile strength. [ABSTRACT FROM AUTHOR]

Influence of multiple structural parameters on the performance of a gun launch system driven by highpressure reactive gases is important for structural design and performance adjustment. A coupled lumped parameter model was utilized to predict the propellant combustion, and a dynamic finite element method was applied to approximate the mechanical interactions between the projectile and the barrel. The combustion and the mechanical interactions were coupled through a user subroutine interface in ABAQUS. The correctness and the capability of the finite element approximations in capturing small structural changes were validated by comparing predicted resistance with experiments. Based on the coupled model, the influence of structural parameters of a medium-caliber gun on the system performance was investigated. In order to reduce the research costs, orthogonal tests were designed to investigate the comprehensive effects of the parameters. According to statistical analysis, the important order of the structural parameters on the launching process was obtained. The results indicate that the influence of the width of the rotating band stands out among the studied parameters in the gun. The work provides a method to investigate the influence of multiple parameters on system performance and gives guidance for controlling the system performance. [ABSTRACT FROM AUTHOR]

Sandstone is an important and common engineering rock, and understanding the meso/macroscale mechanical properties of sandstones under different confinements are crucial for engineering safety. It is still difficult to correlate the mesoscale bonding parameters and macroscale mechanical behavior. In this paper, the Hoek–Brown parallel bond correlation model (HB-PBCM) is proposed based on the mesoscale analysis of the parallel bond model (PBM). The mathematical analytical expression of HB-PBCM is derived from the sensitivity analysis of the PBM parameters to the Hoek–Brown criterion strength parameters. The model is able to reproduce both the PBM and HB parameters obtained from laboratory tests. The parameters were validated via numerical tests, where the final strength and failure patterns of sandstones are shown to be consistent with those via real experiments. Combined with the numerical and experimental results, we find that the macroscale brittle‒ductile transition of sandstone is characterized by the alteration of the tensile-to-shear crack ratio, different mesoscale crack distributions, and mesoscale crack accumulation rates. [ABSTRACT FROM AUTHOR]

Sensitivity analysis of influencing factors on frost resistance is carried out in this paper, and a two-stage neural network model based on grey theory and Back Propagation Neural Networks (BPNNs) is established for the sake of predicting the frost resistance of active-admixture recycled concrete quickly and accurately. Firstly, the influence degree of cement, water, sand, natural aggregate, recycled aggregate, mineral powder, fly ash, fiber and air-entraining agent on the frost resistance of active-admixture recycled-aggregate concrete was analyzed based on the grey system theory, and the primary and secondary relationships of various factors were effectively distinguished. Then, the input layer of the model was determined as cement, water, sand, recycled aggregate and air-entraining agent, and the output layer was the relative dynamic elastic modulus. A total of 120 datasets were collected from the experimental data of another author, and the relative dynamic elastic modulus was predicted using the two-stage BPNN prediction model proposed in this paper and compared with the BPNN prediction results. The results show that the proposed two-stage BPNN model, after removing less-sensitive parameters from the input layer, has better prediction accuracy and shorter run time than the BPNN model. [ABSTRACT FROM AUTHOR]

The widely distributed loess–mudstone strata structure in the Loess Plateau of China is one of the fundamental reasons for the susceptibility and group occurrence of seismic landslides in the area. This study took the loess landslides induced by the Haiyuan earthquake as a case study. Through extensive field investigations, the loess cover thickness, mudstone dip angle, slope height, and slope angle were chosen as the influencing factors. Together with mathematical statistics and geotechnical tests, two models, one of a loess–mudstone slope and the other of a pure loess slope, were constructed. Their seismic stabilities under different slope angles and slope heights were compared to analyze the influence of the underlying mudstone strata on the loess slope seismic stability. Meanwhile, a sensitivity analysis of these strata factors affecting the seismic stability of the loess–mudstone slope was carried out based on the orthogonal test. The results showed that ignoring the underlying mudstone strata would lead to smaller calculation results than the actual situation. The sensitivity influence of the factors on the loess–mudstone slope seismic stability comprised the slope angle, loess cover thickness, slope height, and mudstone dip angle from high to low. [ABSTRACT FROM AUTHOR]

Based on the complex structural characteristics of permanent magnet-assisted synchronous reluctance motors (PMA-SynRMs), this paper proposes a multi-objective optimization design method for the motor using a composite algorithm. Firstly, the power density, electromagnetic torque, cogging torque, and torque fluctuation coefficient were used as optimization targets based on parametric analysis data of 14 motor structure variables, where parametric sensitivity analysis helped select eight optimization variables. Secondly, the motor prediction model was fitted using the genetic algorithm–back propagation (GA-BP) neural network. Finally, non-dominated sorting genetic algorithm-III (NSGA-III), based on the reference points, was used to find the optimization of the prediction model and complete the multi-objective optimization design of the external rotor PMA-SynRM with eight inputs and four outputs. A comparative analysis of the electromagnetic performance of the motor before and after optimization verifies the feasibility of optimizing the motor using the composite algorithm. This paper provides an analytical tool for the multi-parameter and multi-objective PMA-SynRM optimization design. [ABSTRACT FROM AUTHOR]

One-dimensional theoretical methods are always utilized for analysis of performances of a steam ejector but they commonly have certain limitations. Numerical simulation and analysis were carried out by means of CFD method to the flow field inside a steam ejector for recovery of waste heat; moreover, the single-factor analysis was performed to see how the ejector was affected by those single-factors such as the diameter of the nozzle outlet, the distance between the nozzle outlet to the inlet of the mixing chamber and diameters of the contraction section of the mixing chamber and the diffuser chamber, respectively, while other conditions are fixed. Multi-factor analysis was then carried out to investigate the performances of the ejector and its structures were optimized by means of the five-factor and four-level orthogonal tests to gain the sensitivity for each factor to performances of the ejector. Results indicate that the optimized ejector has much better performances and the diameter of the nozzle outlet is the most sensitively influencing factor on performances of the ejector. This study may provide a new way of thinking for optimization of structure parameters of any steam ejector and have certain values for design and application of steam ejectors. [ABSTRACT FROM AUTHOR]

The coal walls in a caving face with a tall mining height are prone to rib spalling, which leads to the phased cessation of the mining of the working face, causes heavy losses, and endangers the safety of underground workers. In order to prevent serious rib spalling accidents of coal walls in fully mechanized caving faces with a large mining height and to improve the prediction of and ability to control rib spalling, a load-bearing mechanical model of the roof–coal wall–support system was established based on the moment-balance relationship. The expressions for the deformation and stress distribution in a coal wall were calculated. Then, the influences of key factors on the horizontal displacement of the coal wall were investigated. A numerical simulation model of the working face was established, and an orthogonal test design was introduced. On this basis, the influences of four factors: cutting height, breaking position of the main roof, support strength, and sidewall protecting force of the support on the horizontal displacement and volume of a plastic zone of coal wall, were analyzed. Moreover, their order of importance was ranked on the basis of sensitivity. Based on the engineering conditions and production practices in the Cuncaota II Coal Mine, key parameters for controlling and measures for preventing the rib spalling of the coal wall are proposed to guide practical actions. [ABSTRACT FROM AUTHOR]

The development of materials formulated for similar simulation testing of small-scale models is the foundation of this work in order to carry out the physical model test investigation of the instability mechanism of the retrieved roadway beneath the legacy coal column on the close coal seam. In this paper, river sand is chosen as the aggregate and gypsum + cement as the cementitious material, and an orthogonal test with three factors and five levels is designed, as well as sensitivity and error source analyses of the test results. The results showed that river sand content and water content had significant inhibitory effects on the longitudinal wave velocity, compressive strength, and tensile strength of similar materials, and had some but not significant effects on density, elastic modulus, and Poisson's ratio of similar materials. The gypsum-cement ratio had no significant effect on any of the six mechanical parameters of similar materials. For the sources of errors in each stage of the whole similar material fabrication process, corresponding methods and measures are proposed to reduce the errors. The experimental results are also fitted by multiple linear regression method, and the fitting results can better provide a reference for the formulation of similar simulation materials for small-scale models. [ABSTRACT FROM AUTHOR]

Due to environmental stresses, photovoltaic (PV) modules operating outdoors may trigger multiple power degradation patterns. In this paper, four types degradation patterns are studied, among which humidity cycling is proposed for the first time. To verify the necessity of the proposed humidity cycle degradation, the sensitivity of the environment on the output power of PV modules is analyzed using orthogonal tests, and the results show that the power degradation of PV modules by humidity cycle is second only to the damp heat degradation. In addition, a method to model the coupling relationship between each degradation patterns based on weight values is proposed to accurately quantify the influence of environment on the output power of PV modules, and the accuracy of the model is verified by actual power plant data. • Propose a new degradation pattern for PV modules: humidity cycling degradation • Construct the coupling relationship between the degradation patterns of PV modules • High accuracy for PV module life prediction [ABSTRACT FROM AUTHOR]

With the development of infrastructure construction, an increasing number of projects are faced with the problem of hydraulic and dynamic coupling. However, traditional physical model materials mainly consider the single factor influence and lack comprehensive research on the hydraulic and dynamic parameters of similar materials. Based on the dimensionless criterion and Buckingham π theorem, the dimension and similarity relation of physical model tests of rock masses under seepage and dynamic coupling are derived. A new type of similar material considering hydraulic and dynamic properties was developed by using quartz sand, barite powder, cement, water glass, rosin, and glycerol as raw materials through a large number of orthogonal tests. Meanwhile, the sensitivity analysis of the physical and mechanical properties of similar materials was carried out and the influence of each component factor on the physical properties was revealed. A material preparation scheme was developed to meet the physical and hydraulic characteristics of different rock and soil physical models. An empirical matching formula considering each parameter is proposed. This work can provide an important reference for physical model tests of similar rock masses.

The hyporheic zone is a transition zone for the exchange of matter and energy between surface water and subsurface water. The study of trends and sensitivities of bed hyporheic exchanges to the various influencing factors is of great significance. The surface−groundwater flow process was simulated using a multiphysics computational fluid dynamics (CFD) method and compared to previous flume experiments. Based on that, the single-factor effects of flow velocity (u), water depth (H), dune wave height (h), and bed substrate permeability (κ) on hyporheic exchange in the bed hyporheic zone were investigated. The sensitivity analysis of various factors (H, u, dune wavelength (L), h, bed substrate porosity (θ), κ, and the diffusion coefficient of solute molecules (Dm)) in the surface−subsurface water coupling model was done using orthogonal tests. The results indicated that u, h, and κ were positively related, whereas H was negatively related to hyporheic exchange. H and u showed large effects, whereas κ, Dm, and θ had moderate effects, and L and h showed small effects on hyporheic exchange. This study provides valuable references for the protection and recovery of river ecology. [ABSTRACT FROM AUTHOR]

The existence of fractures has a significant influence on the mechanical properties of a rock mass. The sensitivity of the rock mass's mechanical properties to the fracture's geometric parameters is conducive to improving the measurement accuracy of fractured rock mass engineering. Firstly, the fracture geometric parameters in the dam site area of Lianghekou Hydropower Station were counted using the ShapeMetriX3D system. Then, the effect of the fracture's geometric parameters on the deformation characteristics, failure mode, and mechanical parameters of the rock mass were investigated based on the RFPA3D under the uniaxial compression test. The results showed that the stress–strain curves of the fractured rock mass mainly exhibited elastic-brittle characteristics. The failure pattern of the fractured rock mass was mainly defined by a compressive-shear composite. Additionally, the influence of the fracture's geometric parameters on the uniaxial compressive strength (UCS) was greater than that of elastic modulus. The sensitivity of the UCS to fracture trace length was more significant. [ABSTRACT FROM AUTHOR]

It is very important to accurately calculate the frost heave force for the frost resistance design of tunnels in cold regions. A computational model will divide the lining and surrounding rock into eight parts, such as the support zone, the frozen zone (e.g., isothermal Rings I, II, III, IV, V, and VI), and the unfrozen surrounding rock Zone VII. The model will consider the influence of the inhomogeneity of the mechanical parameters of the frozen surrounding rocks that are caused by the temperature field on the calculation results for the frost heave force. Based on the case analysis, the elastoplastic analytical solution of the stress and deformation of the surrounding rock in a cold region tunnel will be obtained. The results show that: (1) if the basic physical and mechanical parameters of the frozen surrounding rock are taken as constants, the calculation results of frost heave force, plastic radius (rp), and circumferential stress (σθ) at the excavation radius will be smaller than that of the model proposed in this paper, and the freezing resistance design of the tunnel lining in cold regions based on the uniform parameter model might lead to lining damage due to insufficient support strength in the later stage; (2) the results of variance analysis show that the inner radius of the lining (ra) and radius of Zone 7 (r7) had a significant effect on the frost heave force in all cases, and the elastic modulus of the lining (E0) was significant. The influence of the elastic modulus of Zone 7 (E7) and in situ stress (p0) on the frost heaving force was not significant; and (3) the influence law of the displacement release coefficient (η), E0, and p0 on the force that acted on the lining will be analyzed. The model to calculate the frost heave force and the related conclusions could have guiding significance for the frost resistance design and numerical simulation of tunnels in cold regions. [ABSTRACT FROM AUTHOR]

To develop a model material suitable for analysing the stability of sandstone slopes during strong earthquakes, an orthogonal test was designed by selecting seven physico-mechemical parameters, a combination of dynamic and static parameters, as research indexes. Then, the influence of the proportion of each component in the model material on each test index was determined by sensitivity analysis, and the quantitative relationship between physico-mechanical parameters and component proportions was established by multiple linear regression analysis to develop a model material similar to sandstone. Finally, a sandstone slope along the Duxiang Expressway was taken as an example, and the proportions of the components suitable for a model of the rock mass in this area were determined. The test results showed that (1) the physico-mechanical parameters selected for the dynamic and static tests were used to effectively develop model materials for dynamic geotechnical model tests; (2) samples of model materials composed of barite powder, quartz sand, ferric powder, gypsum and cement met the requirements for dynamic testing of geotechnical models of sandstone slopes; and (3) through sensitivity analysis of various factors and multiple linear regression analysis, the required model materials were efficiently configured, and the failure mode, failure process and physico-mechanical parameters of the model materials accurately simulated the original rock materials. [ABSTRACT FROM AUTHOR]

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Large-diameter buried steel pipes (BSPs) have been widely utilized in water diversion and hydropower fields. This paper presents a comprehensive numerical investigation on the interaction between the large-diameter pipe and soil under three typical working conditions, to capture the structural mechanical behaviors of pipe deformation, soil displacement, and soil pressure. Furthermore, a parametric analysis of pipe diameter is conducted, along with the sensitivity study of soil parameters based on the orthogonal test method. The results show that the water weight increases the pipe deformation significantly by 14%, while the high internal water pressure decreases the deformation greatly with the maximum effect of 39%. The pattern of soil pressure at the top of the pipe changes from parabola to double-hump as the pipe diameter varies from 0.5 m to 5.0 m. The pipe deformation and soil pressure keep increasing with the pipe diameter, but the safety margin for prism load decreases gradually. Pipe deformation and soil pressure are very sensitive to the elastic modulus and Poisson's ratio of backfill. Friction coefficients of soil-soil (trench sidewall) and pipe-soil have great influences on the soil pressure, while the bedding material and backfill cohesion have small effects on it. [ABSTRACT FROM AUTHOR]

Due to stator magnetic saturation and inherent cogging torque, the slotted limited angle torque motor (LATM) performs large torque ripple within its operation range, resulting in vibration noise and complex control problem. The novelty of this article is to not only first to apply 1J22 soft magnetic alloy (SMA) in the LATM but also to propose a multiobjective optimization method to improve the torque performances including torque ripple, cogging torque, and output torque, based on genetic algorithm (GA). First, 1J22 SMA is applied to the LATM to reduce the torque ripple caused by magnetic field saturation. Then, through the sensitivity analysis, weight coefficients of the related parameters of stator tooth for the optimization process are obtained. Besides, in order to optimize torque performances, the multiobjective optimization process is carried out and the GA is used to obtain the desired objective. Finally, the finite-element analysis (FEA) is used to validate the optimization design. [ABSTRACT FROM AUTHOR]

Summary: Structural and flow parameters have a substantial effect on the thermal and hydraulic performance of a lithium‐ion battery and cooling system. In this study, a computational fluid dynamics model is developed for double cold‐plate based liquid cooling for a 20 Ah lithium‐ion pouch cell, and then validated based on experimental data. An orthogonal test consisting of single factor and multi‐factor analysis is designed to obtain the sensitivity of four factors, including the inlet coolant temperature, inlet coolant volume flow rate, number of cooling channels, and maximum channel width that influence the thermal behavior of the pouch cell. The multi‐objective optimization for minimizing maximum temperature, maximum temperature difference and average pressure drop using genetic algorithm is conducted subjected to constraints of operating conditions for optimum battery performance. Based on the multi‐objective optimization, the obtained minimized values for maximum temperature (Tmax), maximum temperature difference (ΔTmax) and average pressure drop (ΔPavg) are 25.25°C, 0.22°C and 48.76 kPa. The minimized objective functions are obtained at the inlet coolant temperature of 25°C, inlet coolant volume flow rate of 240 mL/min, number of cooling channel of 10 and maximum channel width of 1.70 mm. [ABSTRACT FROM AUTHOR]

Investigating the diffusion law of slurry while grouting in fractured aquifer is of great significance to the safety in coal mining. In this paper, we comprehensively studied the slurry diffusion in the fractured aquifer, which was grouted through horizontal injection holes. A theoretical model of slurry diffusion in the inclined tubular fractures, as well as the relationship between the distance of slurry diffusion and the grouting time, was established. Then the influence of different factors on the distance of slurry diffusion was analyzed, including rheological coefficient, the fracture width, grouting pressure, the fracture dip angle, and the velocity of flowing water. Finally, sensitivity analysis on the distance of slurry diffusion for pseudoplastic fluid and expansive fluid along the flowing water direction was made and the results show that the sensitivity of each factor to the diffusion distance of the two fluids along the flowing water is different, rheological index is the very significant factor to the diffusion distance of pseudoplastic fluid. However, for the expansive slurry, the fracture width is the very significant factor to the diffusion distance of it. [ABSTRACT FROM AUTHOR]

Aiming at the uncertainty of material parameters of human brain tissue, the influence of tissue material performance sensitivity on frequency and mode shape under free vibration is studied. In this paper, the 50th percentile finite element (FE) model of human head and neck with detailed anatomical characteristics has been chosen as the research object, the parameters of skull, cerebrospinal fluid (CSF) and brain tissue materials with high sensitivity are analyzed by orthogonal test design and variance analysis. The results show that the natural frequencies of Group 7, Group 8 and Group 9 are all around 230 Hz, which are basically consistent with the initial parameter of 229.18 Hz, and the intracranial displacements of the three groups are also concentrated on the lateral nasal cartilage. The main reason is that the Young's modulus of the skull used in three groups of experiments is 9780 Mpa, which is close to the initial parameter of 8000 Mpa. It indicates that the material parameter of the skull has the greatest influence on the dynamic characteristics of human head and neck, followed by the CSF and brain tissue. This study provides an effective method for vehicle safety and head and neck injury protection, and supplies a reference for FE analysis of head collision damage. [ABSTRACT FROM AUTHOR]

With open-pit mines excavated, the slopes will be exposed to the natural environment for a long time. Affected by factors like temperature, seepage, mining, freeze-thaw, etc., slope structural integrity and strength will gradually decline as slope exposure time extends. Besides, the development of defect structure within the rocks is closely correlated with time. In this paper, freeze-thaw cycle tests were conducted on the saturated sandstones collected from a certain open-pit mine. According to the test results, the mass density and longitudinal wave velocity gradually increased with more times of freeze-thaw cycles while mechanical properties such as internal friction angle, cohesion, elastic modulus, and uniaxial compressive strength decreased instead. The constitutive model of saturated rock deterioration was established by taking the volume of phase transition of water in microcracks as a variable. Based on the tests results and theoretical analysis, the sensitivity of the factors affecting slope stability under freeze-thaw damage was studied by Control Variable Method (CVM) and Orthogonal Design Method (ODM). It was determined that the internal friction angle and cohesion had a highly significant effect on the test results, while the mass density had a significant effect. The conclusions may play a certain role in guiding slope construction and protection. [ABSTRACT FROM AUTHOR]

Groundwater on small coral islands exists in the form of freshwater lenses that serve as an important water resource for local inhabitants and ecosystems. These lenses are vulnerable to salinization due to groundwater abstraction and precipitation variation. Determination of the sustainable yield from freshwater lenses is challenging because the uncertainties of recharge and hydrogeological characteristics make it difficult to predict the lens response to long-term pumping. In this study, nine pumping well layout schemes along a line are designed using the orthogonal experimental design method, and an optimal well layout scheme is determined by multi-index range analysis and comprehensive balance analysis method. The total critical pumping rates of the freshwater lens corresponding to different schemes are calculated by numerical simulation, and the sensitivity of the total critical pumping rates to hydrogeological parameters is analyzed. The results show that the calculation of the total critical pumping rates needs to be combined with the specific well layout scheme with consideration to the length of well screens, the number of wells and the distance between wells. The difference in total critical pumping rates between different schemes can be up to three times. The uncertainty of hydrogeological parameters has a great impact on the total critical pumping rates. Within the range of a 30% reduction in parameters, α and K are the key risk factors of pumping; within the range of a 30% increase in parameters, α, ne and K are the key risk factors; α-ne combined changes had the greatest impact. The management of freshwater lenses and the assessment of sustainable yield will continue to be important tasks for coral islands in the future, and this study can help with the sustainable exploitation of island freshwater lenses. [ABSTRACT FROM AUTHOR]

The article presents information on studies which discusses the interplay of design and disorder for creating a population of differentiated β-cells, and development of several computational methods such as intermodular coupling analysis and phenotypic sensitivity analysis.