Slice Method Research Articles

An analytical method to calculate the time-varying mesh stiffness of spiral bevel gears with cracks

Time-varying mesh stiffness (TVMS) is one of the main dynamic excitation sources of gear transmission systems. The accurate calculation of TVMS is the foundation to comprehensively investigate the vibration of powertrain. Compared with the spur gear, the meshing process of spiral bevel gear is spatially time-varying, which makes the analytical calculation of TVMS more difficult. In this paper, the meshing relationship of spiral bevel gears is first established by extending the slice method of spur and helical gears to spiral bevel gear. Secondly, the analytical models of perfect and cracked spiral bevel gears are presented to evaluate TVMS. Meanwhile, the effects of crack length and depth on mesh stiffness are investigated. Thirdly, the influence of crack length and depth on the dynamic response are simulated based on the 8-DOF dynamic model of spiral bevel gear. Finally, the experiments are conducted to verify the effectiveness of the analytical model. Experimental results demonstrate that the existence of tooth crack fault makes the response characterized by periodic impact with the rotating frequency of cracked pinion.

A general kinematic approach to the seismic stability assessment of slopes

Most of the current studies concerning slope stability assume a toe failure mechanism, which fails to capture the full complexity of slope collapse. In this study, a more comprehensive approach is developed for analyzing seismic slope stability by defining an instability behavior coefficient that considers different failure patterns, including toe, face, and base failure. The proposed coefficient is integrated with a kinematic method of limit analysis to establish a three-dimensional (3D) collapse mechanism that can describe all possible instability behaviors. The impact of earthquake forces on instability behaviors and slope stability is assessed in a modified pseudodynamic manner, which is capable of accounting for the spatiotemporal feature of seismic acceleration. A horizontal slice method is executed for calculating earthquake-induced work rates, as well as a double integral technique to compute dissipation rates due to soil resistance along the sliding surface and work rates generated by soil weight. By applying the principle of energy conservation, the lower-bound solutions of stability numbers are derived, and a further critical solution can be obtained by the combination of the Marine Predators Algorithm and the Nelder-Mead Simplex Algorithm. The proposed method is confirmed to be accurate and effective through comparisons with previous solutions. In addition, a parametric study reveals the effect of the dynamic characteristics of seismic waves on slope stability and instability behaviors. The general approach developed in this study offers a more comprehensive and accurate way to assess seismic slope stability.

One simplified method for seismic stability analysis of an unsaturated slope considering seismic amplification effect

Seismic amplification effect in soil slope is not considered by traditional Newmark method; therefore, there will be some deviation in soil slope seismic stability analysis. In order to determine the effect of seismic amplification effect, a simplified method for unsaturated slope stability evaluation is proposed by coupling the Sweden slice method and Newmark method. Research results show that the seismic amplification effect has a great influence on yield acceleration of the slope while it exerts a little influence on critical slip surface shape; if the seismic amplification effect is not considered, permanent displacement of the slope will be underestimated, and there is potential danger in seismic design of slope engineering. Finally, an unsaturated slope model with 1:20 scale is designed through derivation of similarity law, and progressive failure process of the slope under seismic action is simulated. The results of our proposed method are in good agreement with experimental results, which proves the feasibility of our proposed method. This study can provide a simple and reliable method for evaluating the seismic stability of an unsaturated slope.

Limit-Equilibrium Analysis Using a Lateral Force as Functional

A variational method, using a lateral force as a functional and incorporating equilibrium in-the-small, is proposed for limit equilibrium analysis, in which a conventional safety functional in the form of a quotient and the need to use the method of slices or Lagrange multipliers can be avoided. The lateral force is a real force acting on a retaining wall, but is a fictitious force in slope stability analysis. Furthermore, the fictitious force is related to the factor of safety. The force is a push, pull, or null when the slope is unstable, stable, or critical. By setting this lateral force to zero, a critical stability state can be obtained. The proposed variational method is capable of reproducing the classical solutions and yielding new useful analytical results. The proposed method can be a viable alternative technique, because of its effectiveness and ease of use is comparable to the conventional variational approaches.

Deterioration of Basalt Fiber in Cementitious Material and Mitigation with Basalt Powder

Although basalt fiber (BF) has been used to reinforce cement composite as an eco-friendly material, its effect on basalt fiber–reinforced cement composite (BFRCC) is contradictory. BF was found to be corroded by a pore solution through scanning electron microscopy observation. Owing to the chemical alkali corrosion and physical denudation of the BF in an alkaline environment, the interface bonding between the BF and the cement matrix was weakened, and the toughening effect of the BF could not be fully exerted. Pore structure characterization was examined based on the water uptake kinetics method and image analysis of binary specimen slices. The BF was found to have a detrimental effect on the pore structure because of the inclusion of exogenous bubbles. However, basalt powder (BP) could densify the pore structures of the cementitious materials, especially in the basalt-powder-fiber-reinforced cement composite (BPFRCC), in which it further reduced the corrosion degree of the BF and enhanced the bonding between the BF and cement matrix interfaces. Therefore, BP and BF can synergistically enhance the performance of BPFRCC.

Influence of Soil Suction and Seismic Excitation on Active Earth Pressure

Earthquake-induced slope failures are common occurrences in engineering practice. The rigid gravity retaining wall remains an effective technique in maintaining the slope stability. Based on the pseudo-dynamic approach, the seismic response of unsaturated backfills is studied using the kinematic limit analysis method. To formulate the energy balance equation, a horizontal slice method is proposed. The work rates of unsaturated soil gravity, seismic inertia force and damping force that are all characterized with conspicuous nonlinear distribution characteristics are computed using this method. A series of parametric analysis is conducted regarding the influences of soil suction and seismic excitations on the earth pressure estimations. The results show that the suction effect relates not only to the soil types but also the seismic excitations. The earth pressure is overestimated by 15%–32% when soil suction is not considered in the analyses. For hard backfills, the peak active earth pressure increases slightly and moves towards the negative direction.

Cloud probability: A new uncertain model with fuzziness and randomness properties

In order to overcome the weakness of subjectivity of variable and subjectivity of membership function in fuzzy probability the cloud probability model and its algorithm are proposed. Firstly, the representation model of cloud probability is given based on the fusion of cloud model and fuzzy probability. Then the cloud probability algorithm of continuous random variable based on slice method is proposed. Then the relationship between slice number and cloud probability is discussed. And the cloud probability algorithm of discrete random variable is given. Finally, through the application case of e-commerce intelligent decision-making based on cloud probability the effectiveness of the proposed cloud probability algorithm is verified. The research in this paper has good reference significance for dealing with the events represented by uncertain variables.

Kinematic horizontal slice method for uplift capacity analysis of plate anchors in nonhomogeneous soils with a nonlinear failure criterion

The reliable estimation of uplift capacity of plate anchors becomes necessary for the safe and cost-effective design of various structures against uplift loads. Uplift capacity studies have traditionally been conducted using semi-analytical methods based on plasticity theories, and the previous research has primarily focused on homogeneous soils and a linear failure criterion. Soils, in general, are nonhomogeneous and exhibit nonlinear shear strength behavior. The present study proposes a novel kinematic horizontal slice method within the context of plasticity theory to determine the vertical uplift capacity of various shapes of plate anchors in nonhomogeneous soils using the nonlinear power-law failure criterion. A linear variation of parameters such as initial cohesion, tensile strength, nonlinear coefficient, and unit weight with depth below the ground surface was considered. The effect of nonassociativity for a general nonlinear material has been examined. A detailed parametric study was conducted to explore the effects of various parameters on the uplift capacity of anchors. The results revealed that increasing initial cohesion while decreasing tensile strength, nonlinear coefficient, and unit weight with depth below the ground surface increases anchor uplift capacity, especially for three-dimensional cases. Anchor failure patterns were also investigated for a few parameter combinations. The results of this study were found to be more consistent with those developed in the literature for some specific cases.

An analytical method for the meshing characteristics of asymmetric helical gears with tooth modifications

This paper establishes a time-varying meshing stiffness (TVMS) analytical method for asymmetric helical gear pairs based on the potential energy principle and slice method. The method considers the adjacent teeth' influence on the deformation of the gear body part. The proposed method is verified the reasonableness by finite element (FE) analysis. The basic parameters of asymmetric helical gear such as helical angle, pressure angle and tooth width are estimated for the meshing characteristics. The results show that the increase of helix angle, pressure angle of the driving side, normal modulus and tooth width will affect the contact ratio and maximum meshing stiffness of helical gears. The variation of these parameters can minimize the fluctuation of the TVMS curve when the overlap contact ratio reaches an integer. The variation trend of the loaded-static transmission error (LSTE) is opposite to that of the TVMS curve. The load share ratio (LSR) on a pair of gear pairs will decrease with the increase of the degree of reattachment. Furthermore, the influence of tooth modifications on TVMS is estimated by using the proposed method. The mean value of stiffness is reduced after the tooth modifications. The TVMS curve changes more gently after the tooth tip modification.

Mean structure of the supercritical turbulent spiral in Taylor-Couette flow.

The large-scale laminar/turbulent spiral patterns that appear in the linearly unstable regime of counter-rotating Taylor-Couette flow are investigated from a statistical perspective by means of direct numerical simulation. Unlike the vast majority of previous numerical studies, we analyse the flow in periodic parallelogram-annular domains, following a coordinate change that aligns one of the parallelogram sides with the spiral pattern. The domain size, shape and spatial resolution have been varied and the results compared with those in a sufficiently large computational orthogonal domain with natural axial and azimuthal periodicity. We find that a minimal parallelogram of the right tilt significantly reduces the computational cost without notably compromising the statistical properties of the supercritical turbulent spiral. Its mean structure, obtained from extremely long time integrations in a co-rotating reference frame using the method of slices, bears remarkable similarity with the turbulent stripes observed in plane Couette flow, the centrifugal instability playing only a secondary role. This article is part of the theme issue 'Taylor-Couette and related flows on the centennial of Taylor's seminal Philosophical transactions paper (Part 2)'.

Designing and Manufacturing of Vegetable Slicing Machine

Agro-processing industry is faced with a challenge of slicing of vegetables for immediate consumption. This stems from the fact that the traditional slicing methods use bare hands, and knives. This method is faced with shortcomings of inefficiency, poor hygiene, and significant dangers to injury. If vegetables are not sliced, their drying takes longer, may possibly be spoiled, and cannot be stored for future uses. Therefore, this paper strives to design a vegetable slicing machine to increase the efficiency of the drying process as a post-processing step. The study employed a Pugh’s design model to design the machine and manufacture it. First, the necessary information for the design was collected. Thereafter, the machine was designed according to specifications – 0.5 hp, 1400 rpm motor; with a capacity of slicing of 30 kg/h, at an efficiency of 86%. The prototype was tested using carrots. The whole testing was conducted with no injury, and ease to the users. It is advised to automate the vegetable feeding process and reduce the size for future improvements of the vegetable slicing machine.

Adaptive Slicing-Aided Hyper Inference for Small Object Detection in High-Resolution Remote Sensing Images

In the field of object detection, deep learning models have achieved great success in recent years. Despite these advances, detecting small objects remains difficult. Most objects in aerial images have features that are a challenge for traditional object detection techniques, including small size, high density, high variability, and varying orientation. Previous approaches have used slicing methods on high-resolution images or feature maps to improve performance. However, existing slicing methods inevitably lead to redundant computation. Therefore, in this article we present a novel adaptive slicing method named ASAHI (Adaptive Slicing Aided Hyper Inference), which can dramatically reduce redundant computation using an adaptive slicing size. Specifically, ASAHI focuses on the number of slices rather than the slicing size, that is, it adaptively adjusts the slicing size to control the number of slices according to the image resolution. Additionally, we replace the standard non-maximum suppression technique with Cluster-DIoU-NMS due to its improved accuracy and inference speed in the post-processing stage. In extensive experiments, ASAHI achieves competitive performance on the VisDrone and xView datasets. The results show that the mAP50 is increased by 0.9% and the computation time is reduced by 20–25% compared with state-of-the-art slicing methods on the TPH-YOLOV5 pretrained model. On the VisDrone2019-DET-val dataset, our mAP50 result is 56.4% higher, demonstrating the superiority of our approach.

Comparative Analysis of miRNA-mRNA Regulation in the Testes of Gobiocypris rarus following 17α-Methyltestosterone Exposure.

17α-Methyltestosterone (17MT), a synthetic organic compound commonly found in sewage waters, can affect reproduction in aquatic animals, such as tilapia and yellow catfish. In the present study, male Gobiocypris rarus were exposed to 25, 50, and 100 ng/L of 17α-methyltestosterone (17MT) for 7 days. We first analyzed miRNA- and RNA-seq results to determine miRNA-target gene pairs and then developed miRNA-mRNA interactive networks after 17MT administration. Total weights, total lengths, and body lengths were not significantly different between the test groups and control groups. The paraffin slice method was applied to testes of G. rarus in the MT exposure and control groups. We found that there were more mature sperm (S) and fewer secondary spermatocytes (SSs) and spermatogonia (SGs) in the testes of control groups. As 17MT concentration increased, fewer and fewer mature sperm (S) were observed in the testes of male G. rarus. The results showed that FSH, 11-KT, and E2 were significantly higher in individuals exposed to 25 ng/L 17MT compared with the control groups. VTG, FSH, LH, 11-KT, and E2 were significantly lower in the 50 ng/L 17MT exposure groups compared to the control groups. VTG, FSH, LH, 11-KT, E2, and T were significantly lower in the groups exposed to 100 ng/L 17MT. High-throughput sequencing revealed 73,449 unigenes, 1205 known mature miRNAs, and 939 novel miRNAs in the gonads of G. rarus. With miRNA-seq, 49 (MT25-M vs. Con-M), 66 (MT50-M vs. Con-M), and 49 (MT100-M vs. Con-M) DEMs were identified in the treatment groups. Five mature miRNAs (miR-122-x, miR-574-x, miR-430-y, lin-4-x, and miR-7-y), as well as seven differentially expressed genes (soat2, inhbb, ihhb, gatm, faxdc2, ebp, and cyp1a1), which may be associated with testicular development, metabolism, apoptosis, and disease response, were assayed using qRT-PCR. Furthermore, miR-122-x (related to lipid metabolism), miR-430-y (embryonic development), lin-4-x (apoptosis), and miR-7-y (disease) were differentially expressed in the testes of 17MT-exposed G. rarus. This study highlights the role of miRNA-mRNA pairs in the regulation of testicular development and immune response to disease and will facilitate future studies on the miRNA-RNA-associated regulation of teleost reproduction.

Robotic spray painting path planning for complex surface: boundary fitting approach

AbstractCurrently, most of the robot path planning methods for spray painting are based on slicing the Computer-Aided Design model of the target surface to generate a series of path points. They usually neglect the geometric boundary of the model and the smoothness of the generated path, leading to a non-uniform coating thickness. To ameliorate it, an improved “boundary fitting approach” is proposed. In this method, the upper and lower boundaries of the target surface are firstly detected based on the topology of the stereolithography model. For each pass, several sample points are extracted with a uniform length interval from the intersection points generated by the basic slicing method. The path pass is then described by a fourth-order polynomial curve. It fits the boundary points and sample points for the $z$ - $t$ and $y$ - $t$ relationships, respectively. Based on the spray gun’s motion direction and spray direction, the orientation of each path point is also defined. The parameters of the path pass are optimized by particle swarm optimization to get the optimal uniformity of the resulting coating thickness. Both of the global uniformity and the local uniformity between two adjacent passes are considered. The strength of the proposed approach is validated by comparing the simulation with the basic and other typical algorithms. The results denote that boundary fitting approach could improve the uniformity of coating thickness. It brings about a better performance for the painted workpiece.

Software Package to Support Students’ Research Activities in the Hybrid Intellectual Environment of Mathematics Teaching

The urgent need of society for creative and critical thinkers dictates the need to manage and develop the project-based and research activities of schoolchildren. Neural networks, as effective tools for solving complex, multi-component, multifunctional problems, have created an opportunity to develop tools for the content and quality assessment of project-based, research activities and personal achievements of each student with a dynamic and stratified sampling of complex knowledge, to identify individual educational paths, tools and instructions for research and creative activity reflected on the layers of an artificial neural network. The purpose of this study is to define and develop the concept of supporting a hybrid intelligent system of project-based and research activities in a comprehensive information and educational environment to create an applied intellectual technology that supports project-based and research activities and classifies the growth of schoolchildren’s scientific potential. The paper considers the development of technologies for the pedagogical, algorithmic and information organization of ontological engineering and support models for project-based and research activities, as well as the growth of scientific student training based on the construction of an artificial neural network with a teacher and an array of training samples using expert systems and decision theory. It also defines the selection criteria, hierarchies and content of the generalized constructs of complex knowledge (modern achievements in science) by modeling creative activities while further predicting the growth of a student’s scientific potential based on the layers of the neural network. The original technology of training samples used for constructing hybrid neural networks was determined using expert systems, the psychological method of parallel slices and clustering of the personal characteristics of schoolchildren. An innovative intellectual environment is being introduced into the practice of mathematical education in high schools in Russia. The study made it possible to create applied intelligent technology to support and display the dynamic profiles of the project-based and research activities of schoolchildren and act as a growth classifier of their scientific potential. In terms of concept implementation, the phased growth technology to analyze students’ scientific potential was developed during the study of the generalized construct of complex knowledge. Individual educational workshops for school students to master project-based and research activities and display their dynamic profiles during the implementation of a hybrid intellectual environment for support and decision-making will allow school students to develop their personal potential, increase their educational motivation and allow researchers and educators to realize the potential of adapting modern achievements in science to school mathematics and create conditions for the modernization of educational programs in a developing digital environment.

Based on quality, energy consumption selecting optimal drying methods of mango slices and kinetics modelling

Mangoes have a short shelf life because of their high-water content. This study aimed to compare the effect of three drying methods (HAD, FIRD and VFD) on mango slices to improve product quality and reduce costs. Mangoes were dried at various temperatures (50, 60, 70 °C) with different slice thicknesses (3, 5, 7, 10 mm). Results indicated that FIRD was the most cost-effective with the dried mango containing the highest sugar-acid ratio, and when the mango slices thickness was 7 mm and drying at 70 °C, the ascorbic acid content, rehydration ratio, sugar-acid ratio, and energy consumption per unit volume reached 56.84 ± 2.38 mg/100 g, 2.41 ± 0.05, 83.87 ± 2.14, and 0.53 kWh/L. Among three mathematical models, the Page model described the most satisfactory drying behaviour of mango slices in FIRD. This study provides useful information in mango processing industry and FIRD is supposed to be a promising drying method.

Iterative Horizontal Method of Slices for Global Stability of Slurry Trench in Layered Cohesive-Frictional Soils

This paper presents an iterative horizontal method of slices (iterative HMS) for the global stability analysis of a slurry trench in layered cohesive-frictional soils. The iterative HMS differs from existing HMS models in terms of the assumptions on interslice forces. Preceding HMS techniques postulate that normal interslice forces can be evaluated from overburden pressures, which can lead to the violation of failure criteria along interslice boundaries. The iterative HMS ensures that a limit equilibrium system is established without violating the failure criterion throughout the entire soil mass. This is achieved by iteratively adjusting interslice forces by means of enforcing the failure criterion for the aforementioned problematic slice boundaries violating the failure conditions. The performance of the iterative HMS is evaluated in example problems of a slurry trench in uniform clayey soils and cohesive-frictional strata. The results are compared against solutions obtained using finite-element limit analysis (FELA) and a shear strength reduction FEM (SSRFEM). This comparative analysis shows that the adjustment in interslice forces is important for reasonably assessing trench stability conditions. A parametric analysis is performed by using the iterative HMS to show under what trench construction parameters the adjustment of interslice forces cannot be neglected in the stability analysis of a slurry trench.

Optimum Design of Unsaturated Finite Clayey Slopes Using Second-Order Reliability Method

This paper discusses the second-order reliability-based design optimization (SORBDO) of unsaturated finite slopes. An efficient search algorithm is proposed to locate the most probable slip surfaces using the Morgenstern–Price method of slices. The variability of fitting parameters of the soil water characteristic curve (SWCC) and shear strength parameters have been taken into account for evaluating the reliability of unsaturated finite slopes. Six unsaturated shear strength (USS) models are considered for the analysis of unsaturated soils. The most conservative model for the optimum design of finite slopes is recommended. Moreover, the results indicate that the mean and standard deviation of the fitting parameters of SWCC have a significant effect on the critical centers, critical slip surfaces, and reliability index of the unsaturated finite slopes. The results demonstrate a significant change in the critical centers associated with critical slip surfaces due to the change in the mean and coefficient of variation of the fitting parameters of SWCC. Statistical analysis of the experimental data shows that a positive correlation exists between fitting parameters of SWCC related to air entry value (af) and residual water content (mf). Negative correlations are found between the fitting parameters of SWCC related to air entry value (af) and slope (nf). Similarly, the SWCC fitting parameters related to residual water content (mf) and slope (nf) have negative correlations for clayey soils. It is observed that the correlated value of the reliability index is overestimated with reference to the uncorrelated value for clayey soil slopes. The proposed design charts are beneficial for engineers and practitioners for the sustainable design of unsaturated finite slopes. Overall, the developed rigorous SORBDO framework offers a more rational approach for assessing critical failure surfaces and critical centers, considering the interdependency of random variables.

Granular stresses in granular flows subjected to different obstacles

Although the application and development of continuum approaches demonstrate immense promise to model granular flows, the assumption of isotropic stress state in a constitutive law needs to be carefully examined, especially for accurately modeling the kinematics and kinetics of obstructed granular flows. This paper investigates the effect of obstacles on granular stresses and stress ratios in 3D granular silo flows by using discrete element method (DEM). The adopted obstacles include a conical insert, disk insert, BINSERT, hollow cylinder insert and hollow silo insert, as well as the absence of any insert for comparison. A novel (simple but robust) method with ring measurement cells was proposed to determine average stress tensors for granular flows. An innovative slice method with null friction boundaries was also proposed to significantly reduce DEM computational time. The validity of the proposed DEM model was justified by a repose angle experiment and two numerical verification examples. Results reveal that the blocking effect from the obstacles and the hopper wall of the silos led to a significant increase in normal and shear stresses. The normal stresses exhibited slight anisotropy in steady and uniform granular flows, and resulted in a stress ratio of approximately 1.0, indicating an approximately isotropic stress state. Unlike the normal stresses, the shear stresses however showed strong anisotropy even in the steady and uniform regime. The obstructed granular silo flows exhibited strong anisotropy not only in normal stresses, but also in shear stresses. The stress ratio in the obstructed granular flows can appreciably deviate from unity, varying between 0.27 and 2.24. Moreover, the vertical stresses dominated the contact force transmission in the granular silo flows, and showed the formation of dynamic granular arching.

PENGAMATAN EPIDERMIS DAUN MENGGUNAKAN METODE PRINTING DAN IRISAN PARADERMAL

Observation of leaves, especially the epidermis, is often the focus of research because this part is directly exposed to the environment, so changes that occur in this part can indicate changes in the plant's metabolism. Observation of leaf skin requires preparation in advance, especially in observing wet preparations. There are various methods of leaf skin sample preparation including the printing method and leaf paradermal slices. The purpose of this study was to compare leaf preparations with preparations using the printing method and paradermal slices carried out by students of the Biology at PGRI Ronggolawe University in the Plant Anatomy Practicum course. Data in the form of preparations of leaves Morinda citrifolia and Solanum melongen were observed using an electric microscope with a magnification of 400 times, while Ixora sp. leaves were observed using a light microscope with a magnification of 400 times. The results of the study can be concluded that the printing and paradermal incision methods are optimal for the purpose of observing different leaf characters. The optimal printing method is used on leaves that have little or no trichomes and is very good for observing stomatal openings. While the paradermal slice method is good for use on leaves that have trichomes or not, the use of this method requires good practical skills, besides this method cannot represent leaf stomatal openings at the time of observation because the stomata tend to close.