Graphic Methods in Topological Dynamics

This paper considers the graph sequence graph （f^n ）={x×f^n ： x ∈X} of the iterates f^n of a continuous map f ： X →X on a compact metric space （X, d）. The main aim is to introduce serval limit sets by using different recurrent time sets, and discuss the relation between dynamics of the underlying compact system （X, f） and the structure of these limit sets, from a topological or fractal viewpoint.

Computational fluid dynamic simulations on liquid film behaviors at flooding in an inclined pipe

The complex liquid film behaviors at flooding in an inclined pipe were investigated with computational fluid dynamic(CFD) approaches. The liquid film behaviors included the dynamic wave characteristics before flooding and the transition of flow pattern when flooding happened. The influences of the surface tension and liquid viscosity were specially analyzed. Comparisons of the calculated velocity at the onset of flooding with the available experimental results showed a good agreement. The calculations verify that the fluctuation frequency and the liquid film thickness are almost unaffected by the superficial gas velocity until the flooding is triggered due to the Kelvin–Helmholtz instability. When flooding triggered at the superficial liquid velocity larger than0.15 m·s-1, the interfacial wave developed to slug flow, while it developed to entrainment flow when it was smaller than 0.08 m·s-1. The interfacial waves were more easily torn into tiny droplets with smaller surface tension, eventually evolving into the mist flow. When the liquid viscosity increases, the liquid film has a thicker holdup with more intensive fluctuations, and more likely developed to the slug flow.

Dynamic external fixator combined with limited internal fixation for Pilon reactures

Objective To evaluate effects of manipulative reduction,dynamic external fixator combined with limited internal fixation for the treatment of Pilon fractures.Methods From January 2007 to June 2009,manipulative reduction,dynamic external

High Dynamic Bounding and Jumping Motion of Quadruped Robot Based on Stable Optimization Control

Aiming at the environment such as ravines and obstacles that may be encountered in the actual movement,this paper proposes a method for optimizing the bounding and jumping motion based on the ground touching force trajectory and the air motion trajectory of the quadruped robot.The method of optimizing the ground reaction force according to the speed of the demand and the height of the jump,and adjusting the stance and swing time according to the relationship of dynamics and momentum conservation.At the same time,under the constraints of dynamics and energy consumption of the robot system,considering the jumping distance and height,a method for optimizing the air trajectory of bounding and jumping is proposed.State switching and landing stability control are also added.Finally,the experimental results show that the quadruped robot has strong bounding and jumping ability,and has achieved stable bounding movement and forward jump movement of 0.8 m.

Development of a Notion of Limit as Proximity From Discourse Analysis in Secondary-School Function Classes

Mathematical teaching and learning of an introductory calculus conception of limit in secondary school before students learn the formal definition of limit in higher education are discussed.In this study,applications of the theory of instruction based on“Formalizing Introductory Notions(FIN)”(Nagle,2013),in which a theory incorporating new pedagogical approaches was introduced to describe static notions of limit,without ignoring dynamic notions of limit,are presented to help foster an informal limit conception better aligned with the formal definition.A qualitative discourse analysis based on students’utterances,including students’drawing pictures on graphs,was done.In the results of the investigation,it was found that the students’utterances drawings on a graph of the secants(segments)used static notions of limit supported by dynamic notions of limit according to the operating activities.There were learning activities in which students developed a notion of limit as the proximity of the predicted tangent line of a function.Consequently,students’discussions changed focus to the validation of limit candidates with static notions of limit.To overcome the contradiction of their explanations of the operating activities with dynamic notions of limit,the students changed to an explanation with static notions of limit.In light of the findings,this study suggests adapting the pedagogical approach used by the Nagle(2013).

Risk analysis of dynamic control of reservoir limited water level by considering flood forecast error

Flood control forecast operation mode is one of the main ways for determining the upper bound of dynamic control of flood limited water level during flood season. The floodwater utilization rate can be effectively increased by using flood forecast information and flood control forecast operation mode. In this paper, Dahuofang Reservoir is selected as a case study. At first, the distribution pattern and the bound of forecast error which is a key source of risk are analyzed. Then, based on the definition of flood risk, the risk of dynamic control of reservoir flood limited water level within different flood forecast error bounds is studied. The results show that, the dynamic control of reservoir flood limited water level with flood forecast information can increase the floodwater utilization rate without increasing flood control risk effectively and it is feasible in practice.

Impact Assessment of Plug-in Electric Vehicle Charging Locations on Power Systems with Integrated Wind Farms Incorporating Dynamic Thermal Limits

The increased presence of electric vehicle charging locations in a power system with high penetration of intermittent wind power potentially leads to operation complexities resulting in abnormal impacts.This paper proposes an innovative framework for assessing the impact of plug-in electric vehicle(PEV)charging locations on a power system with integrated wind farms,incorporating dynamic thermal limits(DTLs).The framework comprises Monte Carlo simulation,which is embedded with stochastic modeling of various uncertainties under the key operating conditions.As part of the modeling framework,the transmission lines are ranked in accordance with the lowest level of expected energy not supplied.The PEV charging demand is then modeled by incorporating DTLs and applied to the least stressed transmission lines,following the IEEE 738-2006 standard.The new assessment framework is investigated using an IEEE 24-bus test system.The results demonstrate that applying DTLs on the least stressed transmission lines in conjunction with the integration of decentralized wind farms and strategic charging location of PEVs significantly improves the security of the energy supply and considerably reduces interruption costs,as opposed to not having such a framework.

A Novel Design of Hybrid Energy Storage System for Electric Vehicles

In order to provide long distance endurance and ensure the minimization of a cost function for electric vehicles,a new hybrid energy storage system for electric vehicle is designed in this paper.For the hybrid energy storage system,the paper proposes an optimal control algorithm designed using a Li-ion battery power dynamic limitation rule-based control based on the SOC of the super-capacitor.At the same time,the magnetic integration technology adding a second-order Bessel low-pass filter is introduced to DC-DC converters of electric vehicles.As a result,the size of battery is reduced,and the power quality of the hybrid energy storage system is optimized.Finally,the effectiveness of the proposed method is validated by simulation and experiment.