Material Distribution Model Research Articles

Mixed mode stress intensity factor analysis on edge cracked FGM plate with different material distribution models by XFEM

Mixed mode stress intensity factor analysis on edge cracked FGM plate with different material distribution models by XFEM

A Drone Scheduling Method for Emergency Power Material Transportation Based on Deep Reinforcement Learning Optimized PSO Algorithm

Stable material transportation is essential for quickly restoring the power system following a disaster. Drone-based material transportation can bypass ground transportation’s limitations and reduce transit times. However, the current drone flight trajectory distribution optimization model cannot meet the need for mountainous emergency relief material distribution following a disaster. A power emergency material distribution model with priority conditions is proposed in this paper, along with a two-layer dynamic task-solving framework that takes task dynamics into account. This research proposes an algorithm (TD3PSO) that combines the particle swarm algorithm (PSO) updating technique with the double-delay depth deterministic policy gradient algorithm (TD3) algorithm’s capacity to dynamically parameterize. The final task allocation experiment demonstrates that the modified TD3PSO significantly outperforms the conventional algorithm on the Solomon data set, with an improvement of 26.3% on average over the RLPSO algorithm and a 11.0% reduction in the volatility of the solving impact. When solving under realistic circumstances, the solution effect increases by 1.6% to 13.4%, and the redistribution experiment confirms the framework’s efficacy. As a result, the algorithm and architecture suggested in this paper may successfully address the issue of scheduling drones for power emergencies while enhancing transportation efficiency.

Stress wave propagation analysis of 2D-FGM axisymmetric finite hollow thick cylinder

In this paper, a numerical axisymmetric elastic stress wave propagation analysis of the 2D-FGM hollow thick finite cylinder has been performed. The new accurate material distribution model based on Mori-Tanaka scheme and third-order transition function for 2D-FGMs has been implemented in the graded finite element method with higher-order quadrilateral elements. A non-uniform impulsive pressure has been applied on the one-third of the top inner cylinder wall. Consequently, different wave velocities and reflections from the boundaries have been observed due to the graded distribution of material along with two directions. Moreover, the effects of two-dimensional material property distributions on the stress wave propagations and displacements through the cylindrical wall at different locations have been studied systematically. Normalized effective stresses based on von-Mises criteria has been performed in comparison with the internal impulsive pressure amplitude to provide a measure of the cylinder wall response to the mechanical impact loading, the effective stresses are nearly 2.5 times the internal pressure loading amplitude, closed to the impact location. According to the results, 2D material property gradations has effected the stresses significantly. Alternatively, desired stress values can be achieved through optimal design and appropriate choice of property distribution.

Optimization of emergency supplies paths based on dynamic real-time split deliver

A multi-objective dynamic demand split delivery emergency material distribution model is developed to enhance the efficiency of emergency material distribution and facilitate the smooth progress of safety rescue operations during unconventional emergencies. This model incorporates the psychological view of those affected by disasters. The issue of dynamic demand may be transformed into a static demand problem by dividing the distribution time window into time domains of equal length. The optimization process is thereafter executed in real-time with the timed batch methodology. A refined ant colony method has been developed to address the model by integrating the attributes of the mathematical model, followed by doing an arithmetic case analysis. The findings indicate that the algorithm and mathematical model suggested in this study are efficacious in addressing the emergency material distribution issue, offering valuable decision-making advice and reference.

Multi-period dynamic multi-objective emergency material distribution model under uncertain demand

This paper proposes a multi-period dynamic emergency material distribution (EMD) model under uncertain demand by considering the disaster degree and demand of different affected areas to improve the reasonability of disaster relief material distribution in post-disaster emergencies. The objective is to minimize the unsatisfied demand, materials distribution cost, and the risk of choosing the path to distribute materials. The model also focuses on the heterogeneity of emergency materials, the dynamics of demand, and the diversity of transportation tools. In addition, the demands and transportation times are described by fuzzy numbers to better fit with the real situation. To solve the problem we propose a hybrid multi-objective salp swarm algorithm and sine cosine algorithm (HMSSA-SCA). Furthermore, numerical examples of different scenarios and scales are solved and compared with the multi-objective salp swarm algorithm (MSSA), multi-objective evolutionary decomposition algorithm for emergency resource scheduling (MOEA/D-mdERS), non-dominated sorting genetic algorithm II (NSGA-II), and strength pareto evolutionary algorithm 2 (SPEA2) to verify the performance of the HMSSA-SCA algorithm. Finally, the floods and landslides disaster event in 2011 in Rio de Janeiro state, Brazil is used to verify the effectiveness and accuracy of the model and algorithm in the real case.

Research on Solving Postdisaster Material Distribution and Scheduling with Improved NSGA-II Algorithm.

After the occurrence of major sudden disasters, the dispatching and distribution of disaster relief materials are particularly important, but in the process of distribution, there may be excessive distribution of similar emergency materials, unbalanced distribution volume of relief materials in different disaster-affected points, high distribution cost, and low effective distribution rate. In order to solve the above problems, based on the application of big data, this paper proposes a three-level network postdisaster material scheduling and distribution model and an improved NSGA-II algorithm. The model takes the loss degree of the disaster area and the dynamic change rate of the demand for postdisaster relief materials as the constraints, takes the demand prediction of postdisaster relief materials, the optimization of distribution path, distribution nodes, and the satisfaction of victims as the objectives, and designs the sample average approximation method and the improved NSGA-II algorithm. In order to verify the effectiveness of the proposed model and strategy, through the comparative experiment of NSGA and PSO, it can be seen from the experimental results that the three-level network allocation model and the improved NSGA-II algorithm (nondominated sorting genetic algorithm II) proposed in this paper can not only solve the existing postdisaster relief material allocation and scheduling problem but also reduce the space-time complexity of the problem.

Simulation Optimization Design of Set Parts Supply System for Automobile Assembly Line

This article studies material distribution system of mixed-model assembly line. A new material distribution model, set parts supply (SPS) system, is applied to a practical automobile assembly line (S Company) with a takt time of 80s. Firstly, Plant Simulation is used to build the material assembly system simulation model. For the distribution area subsystem, to maximize picking efficiency, material layout and task allocation plan of distribution area are obtained through simulation combined with genetic algorithm with two-chromosome expansion coding mode. As for material transporting subsystem, Design of Experiment (DOE) method based on simulation model is used to achieve the optimization of system parameters such as number of AGVs, capacity of buffer and so on.

The optimal allocation of emergency materials for multiple points on water based on genetic algorithm

In order to study the shortest time of emergency supplies allocation, the supply chain of rescue materials is divided into three levels that is supply areas, shore rescue points and multiple accident points. Taking the limited period of emergency supplies as a prerequisite, a material distribution model is built for studying the shortest time of material distribution from rescue base to accident site; considering the sustainability of rescue base supplies, a land material distribution model is built for studying the minimum cost of transportation problem. According to the dispatching priority of emergency supplies at each accident site, a genetic algorithm is designed to solve it, and a approximate optimal rescue material distribution plan is obtained.

Dynamic Behaviour of a Conveyor Belt Considering Non-Uniform Bulk Material Distribution for Speed Control

For the conveyor belt, variable material flow influences the energy efficiency of the speed control technology significantly. The fluctuation of material flow on the conveyor belt will lead to the detrimental vibrations on both the belt and the conveyor while the conveyor works at certain speeds. In order to improve the model inaccuracy caused by the uniform bulk material flow assumption in the current conveyor belt model, the paper establishes a high-precision dynamic model that can consider speed control of a conveyor belt under non-uniform bulk material transportation. In this dynamic model, a non-uniform bulk material distribution model is firstly proposed based on laser scanning technology. Then, a high-precision longitudinal dynamic model is proposed to investigate the dynamic behavior of a belt conveyor. Considering the micro-units of actual load on a conveyor belt, it can well describe the transient state of the conveyor belt. These models can be used to determine the optimal speed for safety and energy conservation in operation. Experimental results are used to validate the proposed dynamic model for analyzing belt mechanical behavior under non-uniform bulk material distribution on the belt. The results show that the proposed models can be used for optimizing the operating procedures of belt conveyor systems.

A vibration-test-based calculation method of screening material mass of a mining crank-link type flip-flow screen

ABSTRACT Flip-flow screen is a key equipment for dry screening of wet fine coal, and its working load is of great significance to the screening effect and reliability. In order to obtain material mass load characteristics of a crank-link type flip-flow screen in the screening process, a vibration-test-based method is proposed. A complete dynamic model of the crank-link type flip-flow screen system is established by the centralized mass method. The correlation between the material mass and the kinematic parameters is deduced by dynamic theory analysis. The time-frequency analysis, envelope analysis, and Kolmogorov–Smirnov test are used to analyze the material mass statistical distribution characteristics during the screening process. Also, in the vibration tests at different rotation speeds, the relation between the parameters of the material distribution model and the rotational speed is obtained by the least square method. The results of the field experiment show that the maximum deviation of this method is 6.7%, and the material mass distribution model established by this method can well reflect the working state of the flip-flow screen.

Finite Element Analysis of Stress Distribution Characteristics of Vehicle Retreaded Tire Composite Layer

In order to further reveal the failure and damage mechanism of retreaded tires in use, such as tread delamination and pressure burst, we constructed a retreaded tire material distribution model, a stress constraint model for each layer, and a finite element model. Stress distribution characteristics of the tread, breaker, belt, carcass, sidewall, toe rubber, etc. under free condition and static grounding condition were analyzed by numerical simulation, and the following main conclusions were obtained: Under the free-inflation condition, the tire carcass of the retreaded tire is subjected to the most stress, the belt is next to it, the breaker and the tread are the least, and the stress on the tread and tire shoulder is relatively great. Under the static grounding condition, the belt of the retreaded tire of a vehicle is subjected to the most stress, the carcass next to it, the stress distributions of the belt and the carcass are similar, and the stress on the tread and the breaker is relatively small.

A species distribution model for Paracentrotus lividus: predicted projections of habitat suitability

A species distribution model for Paracentrotus lividus: predicted projections of habitat suitability

Nonlinear stability of moderately thick functionally graded sandwich shells with double curvature in thermal environment

Theoretical closed-form solutions and numerical results for nonlinear stability of the moderately thick functionally graded sandwich shells subjected to thermomechanical loadings are presented in this study. Two proposed material distribution models supported by elastic foundations are examined. The nonlinear strain field is deduced from the first-order shear deformation theory taking the stretching, bending and shear effects into consideration. The Bubnov–Galerkin procedure and harmonic balance principle are utilized to bring about the explicit algebraic expression for the shell static behaviors from governing equations derived from Hamilton's principle. Mechanical buckling loads and critical thermal rises for the shells in spherical, cylindrical, and hyperbolic paraboloid forms are obtained. The effect of geometry, elastic foundations, volume fraction index, material distribution models, buckling modes, and imperfections on the shell stability behaviors are considered in parametric studies. The yielding plateau in the thermal analysis of the spherical shells in case of temperature dependent characteristics is recognized for the first time. Verification studies are also conducted.

Forced vibration analysis of functionally graded porous deep beams

The purpose of this study is to investigate forced vibration analysis of functionally graded porous deep beams under dynamically load. Mechanical properties of the functionally graded deep beam change in the thickness direction with porosity. The beam theories fail to satisfy in the calculation and the boundary conditions of deep beams. So, the plane solid continua model is used in the calculation of deep beams in order to obtain more realistic results. The governing equations of the problems are obtained by using the Hamilton procedure. In the solution of the problem, finite element method is used within the plane solid continua model. The effects of porosity parameters, material distribution and porosity models on the forced vibration responses of functionally graded deep beams are examined and discussed with porosity effects. Numerical results show that porosity plays very important role in the dynamic responses of the functionally graded deep beam. Choosing the suitable functionally graded material distribution, negative effects of the porosity can be decreased. It is necessary to use the plane solid continua model in modelling the deep beams.

A Study of Student Perception on Printed Study Material Distribution Model at Srinivas Institute of Management Studies

A Study of Student Perception on Printed Study Material Distribution Model at Srinivas Institute of Management Studies

A Study of Student Perception on Printed Study Material Distribution Model at Srinivas Institute of Management Studies

Once 160,000 undergraduates in the University of California system were asked to name the obstacles that hinder their academic success, the students listed various aspects, but the number one reason, which was given by 33% of the students, was that they simply didn’t know how to study. This seems to be a hard reality when it comes to even Indian colleges. As a solution to this problem, an Innovative practice was adopted by Srinivas Institute of Management Studies and started to follow a model of distributing " Study Materials" to the pupil for each semester in their undergraduate programme. Since last few years this practice had a mixed response in college from the student community. Students have multiple opinions regarding this approach of college. This study titled “a study of student perception on Printed study material distribution model, a case study of students at Srinivas Institute of Management Studies with special reference to MBA & BBM students” is intended to empirically study the actual students’ perception towards the model and reinvent possible improvements if needed with the help of student’s inputs to facilitate student friendly learning.

FEM simulation of tension struts on adhesion performance of mortar–repair interface

One of the most important performance parameters for repair materials is adhesion of the material to substrate. We conducted finite element model simulations of the tension struts to discuss the factors that enhance the strength and ductility of the repair–substrate (mortar or concrete) interface. One of the features in the simulation lies in the material distribution model reflecting the features of the repair–substrate interface. The main points discussed involve the role of aggregates in repair, the required mechanical properties for the repair, and the relationship between fractographic parameter and the mechanical properties of the interface.

Dynamic Medical Material Distribution Model Based on Epidemic Diffusion Rule and Clustering Approach

Due to the fact that the dynamic medical material distribution is vital to the quick response to urgent demand when the Ebola virus occurs, the optimal distribution approach is explored according to the Ebola virus diffusion rule and different severity of the epidemic. First, we choose the more serious epidemic state of Sierra Leone in West Africa as the research object and the SIQR (susceptible, infected, quarantined, required) epidemic model with pulse vaccination is introduced to describe the Ebola diffusion rule and obtain the demanded vaccine and drug in each pulse. Based on the SIQR model, thirteen areas in Sierra Leone are classified into three emergency levels by clustering analysis. Then a dynamic medical material distribution model is formulated, with goals of both reducing the transportation cost and shortages. The results indicate that the proposed approach can make an outstanding contribution to fight against the Ebola virus.

Prediction of risk of fracture in the tibia due to altered bone mineral density distribution resulting from disuse: A finite element study

The disuse-related bone loss that results from immobilisation following injury shares characteristics with osteoporosis in post-menopausal women and the aged, with decreases in bone mineral density leading to weakening of the bone and increased risk of fracture. The aim of this study was to use the finite element method to: (i) calculate the mechanical response of the tibia under mechanical load and (ii) estimate of the risk of fracture; comparing between two groups, an able-bodied group and spinal cord injury patients group suffering from varying degrees of bone loss. The tibiae of eight male subjects with chronic spinal cord injury and those of four able-bodied age-matched controls were scanned using multi-slice peripheral quantitative computed tomography. Images were used to develop full three-dimensional models of the tibiae in Mimics (Materialise) and exported into Abaqus (Simulia) for calculation of stress distribution and fracture risk in response to specified loading conditions - compression, bending and torsion. The percentage of elements that exceeded a calculated value of the ultimate stress provided an estimate of the risk of fracture for each subject, which differed between spinal cord injury subjects and their controls. The differences in bone mineral density distribution along the tibia in different subjects resulted in different regions of the bone being at high risk of fracture under set loading conditions, illustrating the benefit of creating individual material distribution models. A predictive tool can be developed based on these models, to enable clinicians to estimate the amount of loading that can be safely allowed onto the skeletal frame of individual patients who suffer from extensive musculoskeletal degeneration (including spinal cord injury, multiple sclerosis and the ageing population). The ultimate aim is to reduce fracture occurrence in these vulnerable groups.

Integrated topology optimization with embedded movable holes based on combined description by material density and level sets

This paper presents a novel topology description model for topology optimization problems with embedded movable holes, combining the ability of the level set model for accurate geometrical description of the prescribed hole shapes, and the high efficiency of the material density-based method. By this means, any arbitrary hole shapes can be represented accurately and smoothly, while the topological changes can be easily handled by the material distribution model. An explicit mathematical expression is defined to obtain the actual structural layout by combing both models. Moreover, an effective model for the non-overlap constraint is proposed in a unified and systematic manner to avoid the overlaps between the holes and between each hole and the design domain boundary. Therein, the non-overlap constraint for all the embedded holes is imposed as a single explicit integral constraint over the design domain, thus avoiding the difficulties in the overlap detection of multiple arbitrary-shaped geometries. Such a non-overlap constraint is accurate and differentiable, facilitating an analytical design sensitivity analysis. Numerical examples are given to demonstrate the effectiveness and efficiency of the present method.