For most of circular graph the length of the minimum cycle basis is given. For the others a bound of the length of the minimum cycle basis is given and the given bound is reached.
In this paper, we present the study, modelling and simulation of the duty cycle modulation (DCM) based on SVPWM control technique using Matlab/Simulink software. It is one of the most advanced control techniques of sp...In this paper, we present the study, modelling and simulation of the duty cycle modulation (DCM) based on SVPWM control technique using Matlab/Simulink software. It is one of the most advanced control techniques of space vector modulation (SVM), which can be used for controlling static converters or for controlling electrical machines to achieve better dynamic performance. DCSVM is a control technique that generates control signals for the two-level voltage converter as well as for the intermediate times. The main advantage of this control technique is the reduction of the number of calculations, especially for the trigonometric functions and the generation of the reference voltage. In order to reduce the computational effort, we have designed a DCSVM controller that is able to faithfully reproduce the same vectors and output quantities as a classical SVM. In order to test the functionality and validity of the DCSVM control, we have developed different simulations that result in a total harmonic distortion (THD) of the voltage and current of 41.19% and 15.19% respectively with fundamental values of 61.51 V for the voltage and 2.80 A for the current;in contrast to the SVM which gives 47.27 V for the voltage and 2.01 A for the current with THDs of 77.16% for the voltage and 16.00% for the current. This results in an improvement in the distortion rate of around 25.5%. The results obtained are very satisfactory. The DCSVM is a real competitor to the SVM and its various variants.展开更多
About the stability of a homoclinic cycle or a heteroclinic cycle on a plane there are already many results.However, the stability of a homoclinic cycle or a heteroclinic cycle in space is still unclear up to now. Thi...About the stability of a homoclinic cycle or a heteroclinic cycle on a plane there are already many results.However, the stability of a homoclinic cycle or a heteroclinic cycle in space is still unclear up to now. This letter for the first time gives the criterion for determining the stability of a homoclinic cycle or a heteroclinic cycle and the criterion for 3-dimension weak attractor.展开更多
In this paper, we prove that if any set of ｜E（G）｜- ｜V（G）｜ ＋ 1 facial cycles of a 3-connected planar graph G embedded in the plane doesn＇t form a minimum cycle base of G, then any minimum cycle base of G cont...In this paper, we prove that if any set of ｜E（G）｜- ｜V（G）｜ ＋ 1 facial cycles of a 3-connected planar graph G embedded in the plane doesn＇t form a minimum cycle base of G, then any minimum cycle base of G contains a separating cycle, and G has a minor isomorphic to T6, where T6 is the graph obtained from the complete graph K6 by deleting a path with four edges.展开更多
In this paper, the cycle structures for directed graphs on surfaces are studied. If G is a strongly connected graph, C is a ∏-contractible directed cycle of G, then both of Int（C,∏） and Ext（C,∏） are strongly co...In this paper, the cycle structures for directed graphs on surfaces are studied. If G is a strongly connected graph, C is a ∏-contractible directed cycle of G, then both of Int（C,∏） and Ext（C,∏） are strongly connected graph; the dimension of cycles space of G is identified. If G is a strongly connected graph, then the structure of MCB in G is unique. Let G be a strongly connected graph, if G has been embedded in orientable surface Sg with fw（G） ≥ 2（fw（G） is the face-width of G）, then any cycle base of G must contain at least 2g noncontractible directed cycles; if G has been embedded in non-orientable surface Ng, then any cycle base of G must contain at least g noncontractible directed cycles.展开更多
基金Supported by the NSF of Renmin University of China
文摘For most of circular graph the length of the minimum cycle basis is given. For the others a bound of the length of the minimum cycle basis is given and the given bound is reached.
文摘In this paper, we present the study, modelling and simulation of the duty cycle modulation (DCM) based on SVPWM control technique using Matlab/Simulink software. It is one of the most advanced control techniques of space vector modulation (SVM), which can be used for controlling static converters or for controlling electrical machines to achieve better dynamic performance. DCSVM is a control technique that generates control signals for the two-level voltage converter as well as for the intermediate times. The main advantage of this control technique is the reduction of the number of calculations, especially for the trigonometric functions and the generation of the reference voltage. In order to reduce the computational effort, we have designed a DCSVM controller that is able to faithfully reproduce the same vectors and output quantities as a classical SVM. In order to test the functionality and validity of the DCSVM control, we have developed different simulations that result in a total harmonic distortion (THD) of the voltage and current of 41.19% and 15.19% respectively with fundamental values of 61.51 V for the voltage and 2.80 A for the current;in contrast to the SVM which gives 47.27 V for the voltage and 2.01 A for the current with THDs of 77.16% for the voltage and 16.00% for the current. This results in an improvement in the distortion rate of around 25.5%. The results obtained are very satisfactory. The DCSVM is a real competitor to the SVM and its various variants.
文摘About the stability of a homoclinic cycle or a heteroclinic cycle on a plane there are already many results.However, the stability of a homoclinic cycle or a heteroclinic cycle in space is still unclear up to now. This letter for the first time gives the criterion for determining the stability of a homoclinic cycle or a heteroclinic cycle and the criterion for 3-dimension weak attractor.
文摘In this paper, we prove that if any set of ｜E（G）｜- ｜V（G）｜ ＋ 1 facial cycles of a 3-connected planar graph G embedded in the plane doesn＇t form a minimum cycle base of G, then any minimum cycle base of G contains a separating cycle, and G has a minor isomorphic to T6, where T6 is the graph obtained from the complete graph K6 by deleting a path with four edges.
基金Supported by NSFC(Grant No.10771225)Fundamental Research Funds for the Central University
文摘In this paper, the cycle structures for directed graphs on surfaces are studied. If G is a strongly connected graph, C is a ∏-contractible directed cycle of G, then both of Int（C,∏） and Ext（C,∏） are strongly connected graph; the dimension of cycles space of G is identified. If G is a strongly connected graph, then the structure of MCB in G is unique. Let G be a strongly connected graph, if G has been embedded in orientable surface Sg with fw（G） ≥ 2（fw（G） is the face-width of G）, then any cycle base of G must contain at least 2g noncontractible directed cycles; if G has been embedded in non-orientable surface Ng, then any cycle base of G must contain at least g noncontractible directed cycles.
