Comparison and experiment of pressure drop of radial and annular type magnetorheological valves

The magnetorheological (MR) valve is a smart control mechanism using the magnetorheologcial fluid as the working fluid. The advantages of regulating pressure drop and fast response time make the valve have a promising application prospects in the hydraulic servo system, and the MR valve can also be used as a bypass valve to control the MR damper, which can be applied to the different types of vibration attenuating system. The change of pressure drop of MR valve considering radial and annular fluid flow paths was outlined through theory analysis, numerical simulation and experimental verification. The magnetized resistance gaps of both MR valves were constrained within a width of 2.5 mm and a length of 80 mm. The mathematical models of pressure drop of both MR valves were derived separately. The finite element modelling was carried out using ANSYS/Emag software to investigate the distribution of magnetic flux density and dynamic yield stress, and the analytical pressure drop was also obtained, the maximum theoretical pressure drops for the radial and annular type MR valves are 1930 kPa and 982 kPa respectively. Furthermore, a test rig was set up to test the pressure drop under different applied direct currents and different load cases, the maximum experimental pressure dropts for the radial and annular type MR valves are 950 kPa and 660 kPa, respectively. The simulation and experimental results showed that the pressure drop of the radial type MR valve was superior to that of annular type MR valve under the same geometry conditions and the same electromagnetic parameters. The results can provide a new guideline for design of other types MR valve

On the minimum degree of minimally t t -tough, claw-free graphs

A graph $G$ is minimally $t$-tough if the toughness of $G$ is $t$ and deletion of any edge from $G$ decreases its toughness. Katona et al. conjectured that the minimum degree of any minimally $t$-tough graph is $\lceil 2t\rceil$ and proved that the minimum degree of minimally $\frac{1}2$-tough and $1$-tough, claw-free graphs is 1 and 2, respectively. We have show that every minimally $3/2$-tough, claw-free graph has a vertex of degree of $3$. In this paper, we give an upper bound on the minimum degree of minimally $t$-tough, claw-free graphs for $t\geq 2$

Genetic Algorithm-Based Approaches for Solving Inexact Optimization Problems and their Applications for Municipal Solid Waste Management

This chapter proposes a genetic algorithm (GA)-based approach as an all-purpose problem-solving method for optimization problems with uncertainty. This chapter explains the GA-based method and presents details on the computation procedures involved for solving the three types of inexact optimization problems, which include the ILP, inexact quadratic programming (IQP) and inexact nonlinear programming (INLP) optimization problems