Halin图和Series-Parallel图的星荫度

证明了：(1)所有Halin图的星荫度为3，和(2)所有SeriesParallel图的星荫度小于等于3.

Series-parallel Hybrid Vehicle Control Strategy Design and Optimization Using Real-valued Genetic Algorithm

Despite the series-parallel hybrid electric vehicle inherits the performance advantages from both series and parallel hybrid electric vehicle, few researches about the series-parallel hybrid electric vehicle have been revealed because of its complex co nstruction and control strategy. In this paper, a series-parallel hybrid electric bus as well as its control strategy is revealed, and a control parameter optimization approach using the real-valued genetic algorithm is proposed. The optimization objective is to minimize the fuel consumption while sustain the battery state of charge, a tangent penalty function of state of charge（SOC） is embodied in the objective function to recast this multi-objective nonlinear optimization problem as a single linear optimization problem. For this strategy, the vehicle operating mode is switched based on the vehicle speed, and an ＂optimal line＂ typed strategy is designed for the parallel control. The optimization parameters include the speed threshold for mode switching, the highest state of charge allowed, the lowest state of charge allowed and the scale factor of the engine optimal torque to the engine maximum torque at a rotational speed. They are optimized through numerical experiments based on real-value genes, arithmetic crossover and mutation operators. The hybrid bus has been evaluated at the Chinese Transit Bus City Driving Cycle via road test, in which a control area network-based monitor system was used to trace the driving schedule. The test result shows that this approach is feasible for the control parameter optimization. This approach can be applied to not only the novel construction presented in this paper, but also other types of hybrid electric vehicles.

Series-parallel图的△-SP算法的实现

讨论了图和它的二叉分解树,对图的△画法进行了详细的描述,给出了该算法的实现过程,并且对图的分解series-parallelS-P-SPS-P树建树算法进行了改进。最后,通过一个具体实例演示了该画法的结果。

Design and Strategy of Series-Parallel Hybrid System Based on BSFC

In this paper,a drive control strategy is developed based on the characteristics of series-parallel plug-in hybrid system.Energy management strategies in various modes are established with the basis on the minimum brake specific fuel consumption(BSFC)curve of engine.The control strategy,which is based on rules and system efficiency,is adopted to determine the entry/exit mechanisms of various modes according to battery state of charge(SOC),required power and required speed.The vehicle test results verify that the proposed control strategy can improve vehicle economy efficiently and makes a good effect on engine control.

Series-Parallel图上最小权顶点覆盖3-路问题的有效算法

研究了Series-Parallel图上的顶点覆盖3-路问题,利用动态规划思想,给出一个能在多项式时间内完成的有效算法,该算法的运行时间为O(|V|)。

Series-Parallel图的全选择数与全色数

对 2_连通Series_Parallel图G ,证明了当Δ(G) 4时 ,其全选择数等于Δ(G) +1;在Δ(G) 3时 ,其全色数等于Δ(G) +1;对Δ(G)≠ 3时 ,其边选择数等于其边色数 (即列表染色猜想 ) .由于外平面图是特殊的Series_Parallel图 。

Load Dependent Series-Parallel Systems with Common Bus Performance Sharing Mechanism

A series-parallel system was proposed with common bus performance sharing in which the performance and failure rate of the element depended on the load it was carrying. In such a system,the surplus performance of a sub-system can be transmitted to other deficient sub-systems. The transmission capacity of the common bus performance sharing mechanism is a random variable. Effects of load on element performance and failure rate were considered in this paper. A reliability evaluation algorithm based on the universal generating function technique was suggested. Numerical experiments were conducted to illustrate the algorithm.

Operation control strategy of series-parallel hydraulic hybrid vehicle

A series-parallel hydraulic hybrid system applied to public buses is put torwaro, ano parameters of key components are analyzed and determined. Energy management strategy based on logic thresh- old is designed which is aimed at efficient operation of the overall system considering the operational characteristic of the components and taking the curves of engine, hydraulic pump/motor and hydrau- lic pump as the main design basis; regenerative control strategy which makes regenerative brake sys- tem and frictional brake system work harmoniously is designed to raise recovery rate of regenerative brake energy. System dynamic modeling and simulation results show that the energy control strategy designed here is able to adapt system to changes of working condition and switch the operating mode reasonably. The regenerative braking control strategy is effective in raising the utilization of energy and improving fuel economy.

Existence and Uniqueness of the Dynamic Solution of a Series-Parallel Repairable System Consisting of Three-Unit with Multiple Vacations of a Repairman

We investigate a series-parallel repairable system consisting of three-unit with multiple vacations of a repairman. By using C0-semigroup theory of linear operators in the functional analysis, we prove that the system is well-posed and has a unique positive dynamic solution.

Reliability of a Large Series-parallel System in Variable Operating Conditions

In this paper, a semi-Markov model of system operation processes is proposed and its selected parameters are determined. A series-parallel multi-state system is considered, and its reliability and risk characteristics found. Subsequently, a joint model of system operation process and system multi-state reliability and risk is constructed. Moreover, the asymptotic approach to reliability and risk evaluation of a multi-state series-parallel system in its operation process is applied to a port grain transportation system.

Optimal Redundancy Allocation in Hierarchical Series-Parallel Systems Using Mixed Integer Programming

Reliability optimization plays an important role in design, operation and management of the industrial systems. System reliability can be easily enhanced by improving the reliability of unreliable components and/or by using redundant configuration with subsystems/components in parallel. Redundancy Allocation Problem (RAP) was studied in this research. A mixed integer programming model was proposed to solve the problem, which considers simultaneously two objectives under several resource constraints. The model is only for the hierarchical series-parallel systems in which the elements of any subset of subsystems or components are connected in series or parallel and constitute a larger subsystem or total system. At the end of the study, the performance of the proposed approach was evaluated by a numerical example.

Reliability Optimization of Entropy Based Series-Parallel System Using Global Criterion Method

In this paper, we have considered a series-parallel system to find out optimum system reliability with an additional entropy objective function. Maximum system reliability of series-parallel system is depending on proper allocation of redundancy component in different stage. The goal of entropy based reliability redundancy allocation problem is to find optimal number of redundancy component in each stage such a manner that maximize the system reliability subject to available total system cost. Global criterion method is used to analyze entropy based reliability optimization problem with different weight function of objective functions. Numerical examples have been provided to illustrate the model.

Asymptotic Stability of a Series-Parallel Repairable System Consisting of Three-Unit with Multiple Vacations of a Repairman

We study a series-parallel repairable system consisting of three units with multiple vacations of a repairman. We first show that all points on the imaginary axis except zero belong to the resolvent set of the operator and zero is an eigenvalue of the operator, and then we prove that the semigroup generated by the operator is irreducible. By combining these results with our previous result we deduce that the dynamic solution of the system converges strongly to its steady-state solution. Thus we obtain asymptotic stability of the dynamic solution of the system.

Improved sliding-mode control for tracking global maximum power of triple-series-parallel ladder photovoltaic arrays under uneven shadowing

This paper presents an innovative way to enhance the performance of photovoltaic(PV)arrays under uneven shadowing conditions.The study focuses on a triple-series–parallel ladder configuration to exploit the benefits of increased power generation while ad-dressing the challenges associated with uneven shadowing.The proposed methodology focuses on the implementation of improved sliding-mode control technique for efficient global maximum power point tracking.Sliding-mode control is known for its robustness in the presence of uncertainties and disturbances,making it suitable for dynamic and complex systems such as PV arrays.This work employs a comprehensive simulation framework to comment on the performance of the suggested improved sliding-mode control strategy in uneven shadowing scenarios.Comparative analysis has been done to show the better effectiveness of the suggested method than the traditional control strategies.The results demonstrate a remarkable enhancement in the tracking accuracy of the global maximum power point,leading to enhanced energy-harvesting capabilities under challenging environmental conditions.Furthermore,the proposed approach exhibits robustness and adaptability in mitigating the effect of shading on the PV array,thereby increasing overall system efficiency.This research contributes valuable insights into the development of advanced control strategies for PV arrays,particularly in the context of triple-series–parallel ladder configurations operating under uneven shadowing conditions.Under short narrow shading conditions,the improved sliding-mode control method tracks the maximum power better compared with perturb&observe at 20.68%,incremental-conductance at 68.78%,fuzzy incremental-conductance at 19.8%,and constant-velocity sliding-mode control at 1.25%.The improved sliding-mode control method has 60%less chattering than constant-velocity sliding-mode control under shading conditions.

Adjacent Strong Edge Chromatic Number of Series-Parallel Graphs

In this paper, we will study the adjacent strong edge coloring of series-parallel graphs, and prove that series-parallel graphs of △(G) = 3 and 4 satisfy the conjecture of adjacent strong edge coloring using the double inductions and the method of exchanging colors from the aspect of configuration property. For series-parallel graphs of △(G) ≥ 5, △(G) ≤ x'as(G) ≤ △(G) + 1. Moreover, x'as(G) = △(G) + 1 if and only if it has two adjacent vertices of maximum degree, where △(G) and X'as(G) denote the maximum degree and the adjacent strong edge chromatic number of graph G respectively.

Acyclic edge colorings of planar graphs and series-parallel graphs

A proper edge coloring of a graph G is called acyclic if there is no 2-colored cycle in G. The acyclic edge chromatic number of G, denoted by a (G), is the least number of colors in an acyclic edge coloring of G. Alon et al. conjectured that a (G) Δ(G) + 2 for any graphs. For planar graphs G with girth g(G), we prove that a (G) max{2Δ(G) + 2, Δ(G) + 22} if g(G) 3, a (G) Δ(G) + 2 if g(G) 5, a (G) Δ(G) + 1 if g(G) 7, and a (G) = Δ(G) if g(G) 16 and Δ(G) 3. For series-parallel graphs G, we have a (G) Δ(G) + 1.

Powertrain design and energy management of a novel coaxial series-parallel plug-in hybrid electric vehicle

For a series plug-in hybrid electric vehicle,higher working efficiency can be achieved by the drive system with two small motors in parallel than that with one big motor alone.However,the overly complex structure will inevitably lead to a substantial increase in the development cost.To improve the system price-performance ratio,a new kind of series-parallel hybrid system evolved from the series plug-in hybrid system is designed.According to the technical parameters of the selected components,the system model is established,and the vehicle dynamic property and pure electric drive economy are evaluated.Based on the dynamic programming,the energy management strategy for the drive system under the city driving cycle is developed,and the superiority validation of the system is completed.For the studied vehicle driven by the designed series-parallel plug-in hybrid system,compared with the one driven by the described series plug-in hybrid system,the dynamic property is significantly improved because of the multi-power coupling,and the fuel consumption is reduced by 11.4%with 10 city driving cycles.In a word,with the flexible configuration of the designed hybrid system and the optimized control strategy of the energy management,the vehicle performance can be obviously improved.

Multi-objective parameter optimization for a single-shaft series-parallel plug-in hybrid electric bus using genetic algorithm

Recently, the single-shaft series-parallel powertrain of Plug-in Hybrid Electric Bus （PHEB） has become one of the most popu- lar powertrains due to its alterable operating modes, excellent fuel economy and strong adaptability for driving cycles. Never- theless, for configuring the PHEB with single-shaft series-parallel powertrain in the development stage, it still faces greater challenge than other configurations when choosing and matching the main component parameters. Motivated by this issue, a comprehensive multi-objectives optimization strategy based on Genetic Algorithm （GA） is developed for the PHEB with the typical powertrain. First, considering repeatability and regularity of bus route, the methods of off-line data processing and mathematical statistics are adopted, to obtain a representative driving cycle, which could well reflect the general characteristic of the real-world bus route. Then, the economical optimization objective is defined, which is consist of manufacturing costs of the key components and energy consumption, and combined with the dynamical optimization objective, a multi-objective op- timization function is put forward. Meanwhile, GA algorithm is used to optimize the parameters, for the optimal components combination of the novel series-parallel powertrain. Finally, a comparison with the prototype is carried out to verify the per- formance of the optimized powertrain along driving cycles. Simulation results indicate that the parameters of powertrain com- ponents obtained by the proposed comprehensive multi-objectives optimization strategy might get better fuel economy, meanwhile ensure the dynamic performance of PHEB. In contrast to the original, the costs declined by 18%. Hence, the strat- egy would provide a theoretical guidance on parameter selection for PHEB manufacturers.

The Entire Coloring of Series-Parallel Graphs

The entire chromatic number χ_(vef) (G) of a plane graph G is the minimalnumber of colors needed for coloring vertices, edges and faces of G such that no two adjacent orincident elements are of the same color. Let G be a series-parallel plane graph, that is, a planegraph which contains no subgraphs homeomorphic to K 4. It is proved in this paper that χ_(vef)(G)≤ max{8, Δ(G) + 2} and χ_(vef) (G) = Δ + 1 if G is 2-connected and Δ(G) ≥ 6.

Availability Analysis of a Repairable Series-Parallel System with Redundant Dependency

This paper investigates the steady-state availability of a repairable series-parallel system with redundant dependency.The different types of components and repairmen are taken into account,the failure rate of the operating component varies as the number of other failed components and the repair rate of the failed component is constant in each parallel redundant subsystem.To quantify the redundant dependency,a modified failure dependence function is introduced to determine the failure rate of the components in each subsystem.Markov theory and matrix analysis method are used to get the steady-state probability vector of each subsystem and the steady-state availability of the entire system.A numerical example is presented to illustrate the obtained results and to analyze the effect of redundant dependency class on the system availability.