The planning and construction of tall buildings are regulated by lateral forces such as seismic and wind loads. It is imperative to perform a modal analysis of the framework before performing the dynamic evaluation of the building when subjected to lateral forces. Consequently, building professionals focus on calculating the inherent frequency and associated natural period in tall structures to assess the vibrational behaviour of the building's frame. The current research aims to investigate and evaluate the performance of various tall building frameworks with differing shear wall configurations under free vibration, as the arrangement of shear walls significantly influences the stability of the structure against lateral forces. This investigation employs the eigenvalue estimation method for examining rectangular buildings with various shear wall configurations using the FEM program ETABS. The outcomes of this research include predictions of the natural frequency and mode shape for numerous tall rectangular building simulations with numerous configurations of shear wall components by modal simulation. The natural frequency range, time period, mode shapes, and mass participation factors were extracted from the data. As the model’s stiffness increases due to the incorporation of shear wall, the natural time period diminishes across each configuration It is imperative to perform. The model incorporating centrally positioned shear walls in a core configuration demonstrated a 35% reduction in the fundamental time period compared to rectangular structures without shear walls. The investigation is restricted to the modal evaluation of tall rectangular building frameworks and does not include uncertainty quantification (UQ).
The present paper aimed to study the effect of the hole on the stress distribution and stress intensity factor of the mode I fracture in a perforated plate with an edge crack.For this purpose, a plate with an edge crack and one or two holes near the crack tip is investigated.First, the cracked plate without a hole was analysed with Abaqus software, and the results were validated through Westergaard's analytical method.Then, a plate with an edge crack and one or two holes near the crack tip was also analysed with Abaqus software.The effects of the distance between the hole and the crack tip, as well as the radii of the holes on the stress distribution σy and stress intensity factor KI were also investigated.The findings indicated that making a hole in the plate significantly reduces the amounts of the stress and stress intensity factor at the crack tip if the hole has an appropriate radius and position relative to the crack tip.
This paper aims to present a quantitative investigation of a case study based on a live industrial refrigeration system exhibiting complex and dynamic behaviour such as randomness, concurrency, and time dependency.The study employs a state-space stochastic Markovian process to model the interactions among the key functional elements of the system.Furthermore, the scientific approach pursued in this study would help improve the availability of the considered plant by establishing a trade-off between investment, economy and quality.Based on the analysis of results, a framework for Decision Support Priorities (DSP) is proposed, emphasizing the criticality of various functional units.This framework could also help set and prioritize maintenance, spare parts, and human resource requirements accordingly.
In the hydrodynamic thrust bearing with ultra-low clearance, even the nanoscale surface roughness is comparable to the bearing clearance, and its effect can be very significant.In this paper, the calculations are made for the performance of this bearing when the surface roughness is on the 1nm scale.It was found that the surface roughness effect in the bearing is strongly dependent on the physical adsorption of the fluid to the bearing surface determined by the interaction strength (or potential) between the fluid molecules and the molecules of the bearing surface; it can considerably enhance the load-carrying capacity of the bearing for the strong interaction between the fluid and the bearing surfaces.
SUMMARY This research aims to determine the static response of an arch dam before undertaking a dynamic analysis of the dam due to hydrodynamic and seismic stresses. An arch dam with soil interaction, a dam without soil contact, and a dam between soil and reservoir system were all modelled using ANSYS finite element software. The research intends to determine various deformations and stresses caused by the loads attributed to arch dams in different dam systems. Many different outcomes are mapped out and discussed, mainly as weight differences.
The study investigates the impact of reservoir lining on the hydrodynamic stability of a tailings dam.A 3D coupled fluid-solid finite element model was used for detailed seepage analyses based on conventional flow-net and steady seepage conditions.Pore pressure, stationary seepage velocities, static liquefaction and the ratio between manifested and critical hydraulic gradients were predicted under three different lining conditions.The highest potential for internal erosion and heave was observed in the lined reservoir and starter dam scenario.Although there are environmental benefits, the incorporation of liners in dam design requires a comprehensive engineering assessment of the negative hydrodynamic effects.
A new theory of contact-induced standing waves in rotating tyres is presented.The tyre is run by a rotating drum with a fixed shaft distance as in experiments.The tyre belt is modelled as a rotating ring whereas its sidewalls are modelled via radial stiffness of an elastic foundation supporting the ring.The differential equation of vibrations is reduced to the radial deflection of the ring.Critical rotation speed depends on the inflation pressure and the ring bending stiffness.Different tyre response functions are defined in the rotation speed domain with respect to the critical speed.The contact region between the tyre and the drum is defined considering the increase of the tyre radius due to the centrifugal load.Appropriate boundary conditions are specified in order to ensure a continuity of the ring deformation.Bearing reaction forces, as a result of drum penetration into the tyre, are defined.
The paper presents theoretical studies of a new deformation process combining the stages of equalchannel angular pressing (ECAP) and the Linex scheme.To analyse the resulting deformation forces, the stages of pressing in a matrix and compression by a chain conveyor are separately considered.Equations were provided for determining the forces acting on the drive pulley, ECA matrix, and chain element link.A trial calculation and comparative analysis with the previously known rolling-ECAP process showed that the new ECAP-Linex process allows for a stable deformation process with lower forces and a smaller channel junction angle in the matrix.The values obtained by equations are verified with computer simulation using the finite element method in the Deform program.A comparison of values showed that the force values in the calculation and simulation have a high level of convergence.For all three considered parameters, the difference value did not exceed 3%.
In the past few decades, metaheuristic optimization methods have emerged as an effective approach for addressing structural design problems.Structural optimization methods are based on mathematical algorithms that are population-based techniques.Optimization methods use technology development to employ algorithms to search through complex solution space to find the minimum.In this paper, a simple algorithm inspired by hurricane chaos is proposed for solving structural optimization problems.In general, optimization algorithms use equations that employ the global best solution that might cause the algorithm to get trapped in a local minimum.Hence, this methodology is avoided in this work.The algorithm was tested on several common truss examples from the literature and proved efficient in finding lower weights for the test problems.
In this paper, the simplest directional wind spectrum description is given using surrogate bivariate polynomial radial basis functions (PRBF) with L1 norm smoothed by dense boundary points distribution, which enables an accurate description of the geometry and the calculation of the volume below the observed surface when belonging double integral is known.For that purpose, the direct solution of double integral below the descriptive surface is given for bivariate polynomial RBFs with integer exponents, which is examined for accuracy on two examples, for Franke's 2D function and upper hemisphere.After proven accurate in those examples, the direct description of the directional wind spectrum and the calculation of the joint density function of the wind spectrum is done in the paper, thus proving PRBFs as an efficient method for wind spectrum description.In that way, it is possible to calculate the joint density function (JDF) of the actual measured directional wind spectrum analytically, instead of the theoretical calculations used so far.
Bangladesh is marching forward in the way of the Industry 4.0 adaption process with its strength of human assets and long productive experiences.Bangladesh's traditional tanneries are under pressure to change their unfavourable working conditions into safe and productive ones.The study aims to determine the main risk factors of tanning industries from a related literature review and analyse these challenges to adapt the Industry 4.0.A Fuzzy Analytic Hierarchy Process (Fuzzy-AHP) based Multi-Criteria Decision Making (MCDM) methodology is developed to analyse and determine the most and the least critical risk factors.In addition, the purpose of this paper is to provide recommendations for mitigating the risk factors associated with the conversion of a tannery to Industry 4.0.Paired comparisons were created among the criteria for collecting 12 experts' judgments from different tanneries at different levels to progress the methodology using Fuzzy-AHP geometric mean process.The results have shown that the main four risk factors for Industry 4.0 are: Lack of Commitment from Top Management and Policy Makers' Support (47% weight); Lack of Ability to Meet up Initial Cost (29% weight); Lack of ; and Availability of Cheaper Workforce (9% weight).The judgments given by the experts are acceptable since the paired comparisons are tested with the consistency ratio checking mechanism.
This work proposes a refreshing technique that utilizes the Taylor expansion to improve the computational efficiency of the multi-frequency acoustic scattering problem.The Helmholtz equation in acoustic problems is solved using the boundary element method (BEM).In this work, the Taylor expansion is utilized to separate frequency-dependent terms from the integrand function in the boundary integral equation so that the wave number is independent of the equation system, thereby avoiding the time-consuming frequency sweep analysis.To conquer the non-uniqueness of the solution for the external acoustic field problem, the Burton-Miller method is used to linearly combine the conventional boundary integral equation and the hypersingular boundary integral equation.Moreover, to eliminate the computational difficulties caused by the Burton-Miller method, the Cauchy principal value and the Hadamard finite part integral method are used to solve singular integrals.Two-dimensional numerical examples are exploited to verify the effectiveness and compatibility of the algorithm for the multi-frequency analysis.
Proper glucose control is designed to prevent or delay the complications of diabetes.Various contexts can lead to a fluctuation of the blood sugar level to a greater or lesser extent.It can be, for example, eating habits, treatment, intense physical activity, etc.The feeding problem interpolated by a minimum cost function is well-known in the literature.The main goal of this paper is to introduce a multiobjective programming model with constraints for the diet problem with two objective functions, the first of which is the total glycemic load of the diet while the second objective function is the cost of the diet.the MOGA (multiobjective Genetic Algorithm) algorithm was used to resolve the proposed model.The experimental results show that our system ([proposed model -MOGA]) is able to produce adequate diets that can settle glycemic load and cost while respecting the patient's requirements.
This study presents information regarding the development of a localized laser induced heat treatment for aluminum alloys. Such process is intended to improve the forming behavior of aluminum parts in challenging metal forming conditions. This study details information on material, heat treatment parameters as well as results for strength, hardness and elongation properties. It was concluded that it is possible to locally modify yield strength and hardness using laser control parameters and process duration suitable for industrial applications.
SUMMARY Estimation of vehicle dynamics, tire wear, and road profile are indispensable prefaces in the development of automobile manufacturing due to the growing demands for vehicle safety, stability, and intelligent control, economic and environmental protection. Thus, vehicle state estimation approaches have captured the great interest of researchers because of the intricacy of vehicle dynamics and stability control systems. Over the last few decades, great enhancement has been accomplished in the theory and experiments for the development of these estimation states. This article provides a comprehensive review of recent advances in vehicle dynamics, tire wear, and road profile estimations. Most relevant and significant models have been reviewed in relation to the vehicle dynamics, roll angle, tire wear, and road profile states. Finally, some suggestions have been pointed out for enhancing the performance of the vehicle dynamics models.
Numerical analysis of fluid flow and natural convection heat transfer of Fe3O4-water nanofluid around a heated rectangular cylindrical barrier placed in a square cavity was conducted using COMSOL Multiphysics 5.5 software.The effects of nanoparticles volume fraction (0 ≤ ≤ 0.06), aspect ratio (0.1 ≤ ≤ 0.7), and Rayleigh number (10 ≤ ≤ 10 ) on heat transfer and fluid flow due to natural convection in the cavity were analyzed.The heated rectangular cylinder walls were set to have a higher constant temperature while the enclosure walls were maintained at a lower fixed temperature.Results are reported in form of velocity streamlines, isothermal contours, local and average Nusselt numbers.Also, the average Nusselt number for all the walls of the heated rectangular cylinder was found to be independent of Rayleigh number in the range of 10 ≤ ≤ 10 for the various nanoparticle volume fractions (0 ≤ ≤ 0.06) considered.Furthermore, the average Nusselt number of the walls of the cylinder increases with increasing Rayleigh number and aspect ratio.
Generalized Griffith’s criterion and models with pre-destruction zones are considered in this paper. Unlike those models that used linear dependences, the authors proposed the destruction process to be represented by differential equations. The positive effect of such representation is the possibility to formulate boundary conditions using the corresponding constant in the differential equation solution. The result is that the critical load values responsible for the occurrence and propagation of quasi-brittle cracks in materials are obtained. It is stated that the maximum load of crack propagation completely or essentially depends on its initial length. These generalizations estimate the influence of stress caused by hydrogen close to crack-like defects. In the case of defect-free material, the established formula is used to determine the critical forces necessary for the occurrence of cracks with a definite length. Numerical examples for some types of materials are given to illustrate the theoretical estimates.
Control of inventory is a crucial management task that can affect a company's success and survival, and good inventory control offers many benefits.In this paper, the Analytic Hierarchy Process (AHP) method is used to investigate key inventory indicators at a manufacturer and obtained an initial set of factors influencing inventory control, including five major assessment dimensions and 15 assessment criteria."Rolling customer demand forecast accuracy" was a key assessment dimension that can be used to evaluate the case company's inventory.The five most important key inventory control indicators consisted of "forecasting accuracy," "purchases in China," "production, sale, and inventory (PSI) meeting," "skilled worker turnover rate," and "major changes in market demand."In addition, these key indicators are discussed and some practical recommendations are made.
