Over the past decade, open-source software use has grown. Today, many companies including Google, Microsoft, Meta, RedHat, MongoDB, and Apache are major participants of open-source contributions. With the increased us...Over the past decade, open-source software use has grown. Today, many companies including Google, Microsoft, Meta, RedHat, MongoDB, and Apache are major participants of open-source contributions. With the increased use of open-source software or integration of open-source software into custom-developed software, the quality of this software component increases in importance. This study examined a sample of open-source applications from GitHub. Static software analytics were conducted, and each application was classified for its risk level. In the analyzed applications, it was found that 90% of the applications were classified as low risk or moderate low risk indicating a high level of quality for open-source applications.展开更多
The occurrence of high frequency resonances(HFRs)has been frequently observed in several MMC-HVDC projects.To avoid these HFRs,the controller design of an MMC must satisfy two requirements:1)The controller should rema...The occurrence of high frequency resonances(HFRs)has been frequently observed in several MMC-HVDC projects.To avoid these HFRs,the controller design of an MMC must satisfy two requirements:1)The controller should remain stable while in the high frequency range,and 2)MMC impedance should not possess a negative real part in the high frequency range.So far,majority of the related studies on MMC controller design have been unable to address these requirements precisely.This paper first describes the simplified high frequency MMC impedance model developed indigenously by the authors.Subsequently,the driving mechanism of two kinds of HFRs is revealed using the said developed model,including:1)MMC controller instability,and 2)Interaction instability between MMC and AC cables.Furthermore,the mathematical expressions outlining the controller stability constraint and positive damping constraint are proposed.Additionally,NSGA-III based multi-objective optimization algorithm is adopted,to identify the region most suitable for satisfying the proposed stability constraints under the MMC controller parameters.The proposed controller design method is capable of effectively evading the HFRs triggered by the incompatible MMC.The detailed time-domain simulations generated using PSCAD/EMTDC software validate the proposed designed method and endorse the improved results.展开更多
In high speed three-dimensional integrated circuits （3D ICs）, through silicon via （TSV） insertion causes impedance discontinuities along the interconnect-TSV channel that results in signal reflection. As demonstra...In high speed three-dimensional integrated circuits （3D ICs）, through silicon via （TSV） insertion causes impedance discontinuities along the interconnect-TSV channel that results in signal reflection. As demonstrated for a two-plane interconnect structure connected by a TSV, we incorporate an appropriate capacitance at the junction to mitigate the signal reflection with gigascale frequencies. Based on 65 nm technology and S-parameter analysis, the decrease of signal reflection can be 189% at the tuned frequency of 5 GHz. Extending this method to the five-plane interconnect structure further, the reduction of signal reflection can achieve 400%. So we could broaden this method to any multilevel 3D interconnect structures. This method can also be applied to a circuit with tunable operating frequencies by digitally connecting the corresponding matching capacitance into the circuit through switches. There are remarkable improvements of the quality of the transmitting signals.展开更多
This paper focuses on studying the integration method of a generalized Birkhoffian system.The method of variation on parameters for the dynamical equations of a generalized Birkhoffian system is presented.The procedur...This paper focuses on studying the integration method of a generalized Birkhoffian system.The method of variation on parameters for the dynamical equations of a generalized Birkhoffian system is presented.The procedure for solving the problem can be divided into two steps：the first step,a system of auxiliary equations is constructed and its general solution is given;the second step,the parameters are varied,and the solution of the problem is obtained by using the properties of generalized canonical transformation.The method of variation on parameters for the generalized Birkhoffian system is of universal significance,and we take a nonholonomic system and a nonconservative system as examples to illustrate the application of the results of this paper.展开更多
文摘Over the past decade, open-source software use has grown. Today, many companies including Google, Microsoft, Meta, RedHat, MongoDB, and Apache are major participants of open-source contributions. With the increased use of open-source software or integration of open-source software into custom-developed software, the quality of this software component increases in importance. This study examined a sample of open-source applications from GitHub. Static software analytics were conducted, and each application was classified for its risk level. In the analyzed applications, it was found that 90% of the applications were classified as low risk or moderate low risk indicating a high level of quality for open-source applications.
基金supported by the National Natural Science Foundation of China (52207099).
文摘The occurrence of high frequency resonances(HFRs)has been frequently observed in several MMC-HVDC projects.To avoid these HFRs,the controller design of an MMC must satisfy two requirements:1)The controller should remain stable while in the high frequency range,and 2)MMC impedance should not possess a negative real part in the high frequency range.So far,majority of the related studies on MMC controller design have been unable to address these requirements precisely.This paper first describes the simplified high frequency MMC impedance model developed indigenously by the authors.Subsequently,the driving mechanism of two kinds of HFRs is revealed using the said developed model,including:1)MMC controller instability,and 2)Interaction instability between MMC and AC cables.Furthermore,the mathematical expressions outlining the controller stability constraint and positive damping constraint are proposed.Additionally,NSGA-III based multi-objective optimization algorithm is adopted,to identify the region most suitable for satisfying the proposed stability constraints under the MMC controller parameters.The proposed controller design method is capable of effectively evading the HFRs triggered by the incompatible MMC.The detailed time-domain simulations generated using PSCAD/EMTDC software validate the proposed designed method and endorse the improved results.
基金supported by the National Natural Science Foundation of China(No.61204044)
文摘In high speed three-dimensional integrated circuits （3D ICs）, through silicon via （TSV） insertion causes impedance discontinuities along the interconnect-TSV channel that results in signal reflection. As demonstrated for a two-plane interconnect structure connected by a TSV, we incorporate an appropriate capacitance at the junction to mitigate the signal reflection with gigascale frequencies. Based on 65 nm technology and S-parameter analysis, the decrease of signal reflection can be 189% at the tuned frequency of 5 GHz. Extending this method to the five-plane interconnect structure further, the reduction of signal reflection can achieve 400%. So we could broaden this method to any multilevel 3D interconnect structures. This method can also be applied to a circuit with tunable operating frequencies by digitally connecting the corresponding matching capacitance into the circuit through switches. There are remarkable improvements of the quality of the transmitting signals.
基金supported by the National Natural Science Foundation of China (10972151)
文摘This paper focuses on studying the integration method of a generalized Birkhoffian system.The method of variation on parameters for the dynamical equations of a generalized Birkhoffian system is presented.The procedure for solving the problem can be divided into two steps：the first step,a system of auxiliary equations is constructed and its general solution is given;the second step,the parameters are varied,and the solution of the problem is obtained by using the properties of generalized canonical transformation.The method of variation on parameters for the generalized Birkhoffian system is of universal significance,and we take a nonholonomic system and a nonconservative system as examples to illustrate the application of the results of this paper.
