Technical debt(TD)happens when project teams carry out technical decisions in favor of a short-term goal(s)in their projects,whether deliberately or unknowingly.TD must be properly managed to guarantee that its negati...Technical debt(TD)happens when project teams carry out technical decisions in favor of a short-term goal(s)in their projects,whether deliberately or unknowingly.TD must be properly managed to guarantee that its negative implications do not outweigh its advantages.A lot of research has been conducted to show that TD has evolved into a common problem with considerable financial burden.Test technical debt is the technical debt aspect of testing(or test debt).Test debt is a relatively new concept that has piqued the curiosity of the software industry in recent years.In this article,we assume that the organization selects the testing artifacts at the start of every sprint.Implementing the latest features in consideration of expected business value and repaying technical debt are among candidate tasks in terms of the testing process(test cases increments).To gain the maximum benefit for the organization in terms of software testing optimization,there is a need to select the artifacts(i.e.,test cases)with maximum feature coverage within the available resources.The management of testing optimization for large projects is complicated and can also be treated as a multi-objective problem that entails a trade-off between the agile software’s short-term and long-term value.In this article,we implement a multi-objective indicatorbased evolutionary algorithm(IBEA)for fixing such optimization issues.The capability of the algorithm is evidenced by adding it to a real case study of a university registration process.展开更多
In measuring the present scale of China’s public debt, two different types of indexes, stock index and flow index, should be employed separately. The scale of public debt in China, developing from zero in 1979 to wha...In measuring the present scale of China’s public debt, two different types of indexes, stock index and flow index, should be employed separately. The scale of public debt in China, developing from zero in 1979 to what it is today in a short period of a little over 20 years, results from the compound effects of factors such as institutional reform, tax "default", non-standardized government revenue, borrowing new debts to repay old ones, and an expansionary fiscal policy. Under the background of China’s current situation, to prevent the latent risk of public debt, we must focus on diminishing the comparatively high debt dependence degree with mutual effects of multiple factors.展开更多
Due to the need of debt constraint and the fiscal policies issued,it’s possible that China will focus on the adoption of the MTEF(Medium-Term Expenditure Framework)and the MTEF will be one key reform field.Based on t...Due to the need of debt constraint and the fiscal policies issued,it’s possible that China will focus on the adoption of the MTEF(Medium-Term Expenditure Framework)and the MTEF will be one key reform field.Based on the data of 178 counties or regions from 1991 to 2008 published by the World Bank,this paper verifies the effectiveness of the MTEF adoption to the debt scale constraint and finds that the MTEF adoption can help reduce the government debt scale and the two basic levels of MTEF can play this role.What’s more,we conduct another empirical research to find out which factors can influence the MTEF upgrade(upgrade means developing from nonperformance of the MTEF to performance or from the initial stage of the MTEF to the advanced one),finding that the debt scale,the executing time of the MTEF,the regional influence,the support from some international organizations and the development degree have obvious effect on upgrade.Meanwhile,there are opposite effect direction in different debt scale.If the debt scale is above the International Warning Line of 60%,larger scale of debt will lead to MTEF level maintenance(no upgrade).Otherwise,if below the International Warning Line of 60%,larger scale of debt will help the MTEF to upgrade.展开更多
A primary problem affecting perturbative quantum chromodynamic （pQCD） analyses is the lack of a method for setting the QCD running-coupling renormalization scale such that maximally precise fixed-order predictions f...A primary problem affecting perturbative quantum chromodynamic （pQCD） analyses is the lack of a method for setting the QCD running-coupling renormalization scale such that maximally precise fixed-order predictions for physical observables are obtained. The Principle of Maximum Conformality （PMC） eliminates the ambiguities associated with the conventional renormalization scale-setting procedure, yielding predictions that are independent of the choice of renormalization scheme. The QCD coupling scales and the effective number of quark flavors are set orderby-order in the pQCD series. The PMC has a solid theoretical foundation, satisfying the standard renormalization group invariance condition and all of the self-consistency conditions derived from the renormalization group. The PMC scales at each order are obtained by shifting the arguments of the strong force coupling constant as to eliminate all non-conformal {βi} terms in the pQCD series. The {βi} terms are determined from renormalization group equations without ambiguity. The correct behavior of the running coupling at each order and at each phase-space point can then be obtained. The PMC reduces in the Nc → 0 Abelian limit to the Gell-Mann-Low method. In this brief report, we summarize the results of our recent application of the PMC to a number of collider processes, emphasizing the generality and applicability of this approach. A discussion of hadronic Z decays shows that, by applying the PMC, one can achieve accurate predictions for the total and separate decay widths at each order without scale ambiguities. We also show that, if one employs the PMC to determine the top-quark pair forward-backward asymmetry at the next-to-next-to-leading order level, one obtains a comprehensive, self-consistent pQCD explanation for the Tevatron measurements of the asymmetry. This accounts for the ＂increasing-decreasing＂ behavior observed by the DO collaboration for increasing tt invariant mass. At lower energies, the angular distributions of heavy quarks can be used to obtain a direct determination of the heavy quark potential. A discussion of the angular distributions of massive quarks and leptons is also presented, including the fermionic component of the two-loop corrections to the electromagnetic form factors. These results demonstrate that the application of the PMC systematically eliminates a major theoretical uncertainty for pQCD predictions, thus increasing collider sensitivity to possible new physics beyond the Standard Model.展开更多
投弃式海流剖面仪(Expendable Current Profiler,XCP)周围流场是典型的旋转圆柱绕流。探头周围流场对探头的运动状态起决定性作用,这直接关系到探头的测量性能,因此有必要对旋转圆柱周围流场进行实验研究。实验在循环水槽中进行,通过PI...投弃式海流剖面仪(Expendable Current Profiler,XCP)周围流场是典型的旋转圆柱绕流。探头周围流场对探头的运动状态起决定性作用,这直接关系到探头的测量性能,因此有必要对旋转圆柱周围流场进行实验研究。实验在循环水槽中进行,通过PIV对雷诺数保持不变(Re=1000)、不同圆柱旋转速度比(α=0、0.5、1.0、1.5、2.0、2.5、3.0、3.5、4.0、4.5和5.0)的圆柱下游尾流场进行研究。通过选取不同旋转速度比的任一时刻的瞬态流场,来分析旋转对圆柱尾流结构的影响。为了获得流场的频率信息,对所获得流场信息进行能谱分析来获取涡旋的脱落频率,并进一步使用正交模态分解对流场进行分析,给出了流场主要拟序结构及其能量与转速比的变化趋势。发现圆柱旋转改变圆柱尾流结构,使尾迹尺度变小。在旋转速度比0≤α≤2.0时,存在明显的周期性涡旋脱落,并且涡旋脱落的频率有逐渐升高的趋势;而且当转速比2.0<α≤5.0时尾迹流场的周期性减弱,涡旋脱落变得不明显,流场表现出低频、剪切层的区域特征。随着转速变大,涡旋尺度变小。在较高旋转速度比时,流场中能量被重新分布。展开更多
基金The authors would like to thank the Deanship of Scientific Research at Umm Al-Qura University for supporting this work by Grant Code:(22UQUyouracademicnumberDSRxx).
文摘Technical debt(TD)happens when project teams carry out technical decisions in favor of a short-term goal(s)in their projects,whether deliberately or unknowingly.TD must be properly managed to guarantee that its negative implications do not outweigh its advantages.A lot of research has been conducted to show that TD has evolved into a common problem with considerable financial burden.Test technical debt is the technical debt aspect of testing(or test debt).Test debt is a relatively new concept that has piqued the curiosity of the software industry in recent years.In this article,we assume that the organization selects the testing artifacts at the start of every sprint.Implementing the latest features in consideration of expected business value and repaying technical debt are among candidate tasks in terms of the testing process(test cases increments).To gain the maximum benefit for the organization in terms of software testing optimization,there is a need to select the artifacts(i.e.,test cases)with maximum feature coverage within the available resources.The management of testing optimization for large projects is complicated and can also be treated as a multi-objective problem that entails a trade-off between the agile software’s short-term and long-term value.In this article,we implement a multi-objective indicatorbased evolutionary algorithm(IBEA)for fixing such optimization issues.The capability of the algorithm is evidenced by adding it to a real case study of a university registration process.
文摘In measuring the present scale of China’s public debt, two different types of indexes, stock index and flow index, should be employed separately. The scale of public debt in China, developing from zero in 1979 to what it is today in a short period of a little over 20 years, results from the compound effects of factors such as institutional reform, tax "default", non-standardized government revenue, borrowing new debts to repay old ones, and an expansionary fiscal policy. Under the background of China’s current situation, to prevent the latent risk of public debt, we must focus on diminishing the comparatively high debt dependence degree with mutual effects of multiple factors.
文摘Due to the need of debt constraint and the fiscal policies issued,it’s possible that China will focus on the adoption of the MTEF(Medium-Term Expenditure Framework)and the MTEF will be one key reform field.Based on the data of 178 counties or regions from 1991 to 2008 published by the World Bank,this paper verifies the effectiveness of the MTEF adoption to the debt scale constraint and finds that the MTEF adoption can help reduce the government debt scale and the two basic levels of MTEF can play this role.What’s more,we conduct another empirical research to find out which factors can influence the MTEF upgrade(upgrade means developing from nonperformance of the MTEF to performance or from the initial stage of the MTEF to the advanced one),finding that the debt scale,the executing time of the MTEF,the regional influence,the support from some international organizations and the development degree have obvious effect on upgrade.Meanwhile,there are opposite effect direction in different debt scale.If the debt scale is above the International Warning Line of 60%,larger scale of debt will lead to MTEF level maintenance(no upgrade).Otherwise,if below the International Warning Line of 60%,larger scale of debt will help the MTEF to upgrade.
基金Acknowledgements This review is based on a contribution by S.J.B. at the Conference Workshop on Physics at a Future High Intensity Collider @ 2-7 GeV in Hefei, China, on January 14 16, 2015. This work was supported in part by the National Natural Science Foundation of China under Grant No. 11275280, the Department of Energy Contract No. DE-AC02-76SF00515, and Fundamental Research Funds for the Central Universities under Grant No. CDJZR305513. SLAC-PUB-16357.
文摘A primary problem affecting perturbative quantum chromodynamic （pQCD） analyses is the lack of a method for setting the QCD running-coupling renormalization scale such that maximally precise fixed-order predictions for physical observables are obtained. The Principle of Maximum Conformality （PMC） eliminates the ambiguities associated with the conventional renormalization scale-setting procedure, yielding predictions that are independent of the choice of renormalization scheme. The QCD coupling scales and the effective number of quark flavors are set orderby-order in the pQCD series. The PMC has a solid theoretical foundation, satisfying the standard renormalization group invariance condition and all of the self-consistency conditions derived from the renormalization group. The PMC scales at each order are obtained by shifting the arguments of the strong force coupling constant as to eliminate all non-conformal {βi} terms in the pQCD series. The {βi} terms are determined from renormalization group equations without ambiguity. The correct behavior of the running coupling at each order and at each phase-space point can then be obtained. The PMC reduces in the Nc → 0 Abelian limit to the Gell-Mann-Low method. In this brief report, we summarize the results of our recent application of the PMC to a number of collider processes, emphasizing the generality and applicability of this approach. A discussion of hadronic Z decays shows that, by applying the PMC, one can achieve accurate predictions for the total and separate decay widths at each order without scale ambiguities. We also show that, if one employs the PMC to determine the top-quark pair forward-backward asymmetry at the next-to-next-to-leading order level, one obtains a comprehensive, self-consistent pQCD explanation for the Tevatron measurements of the asymmetry. This accounts for the ＂increasing-decreasing＂ behavior observed by the DO collaboration for increasing tt invariant mass. At lower energies, the angular distributions of heavy quarks can be used to obtain a direct determination of the heavy quark potential. A discussion of the angular distributions of massive quarks and leptons is also presented, including the fermionic component of the two-loop corrections to the electromagnetic form factors. These results demonstrate that the application of the PMC systematically eliminates a major theoretical uncertainty for pQCD predictions, thus increasing collider sensitivity to possible new physics beyond the Standard Model.
文摘投弃式海流剖面仪(Expendable Current Profiler,XCP)周围流场是典型的旋转圆柱绕流。探头周围流场对探头的运动状态起决定性作用,这直接关系到探头的测量性能,因此有必要对旋转圆柱周围流场进行实验研究。实验在循环水槽中进行,通过PIV对雷诺数保持不变(Re=1000)、不同圆柱旋转速度比(α=0、0.5、1.0、1.5、2.0、2.5、3.0、3.5、4.0、4.5和5.0)的圆柱下游尾流场进行研究。通过选取不同旋转速度比的任一时刻的瞬态流场,来分析旋转对圆柱尾流结构的影响。为了获得流场的频率信息,对所获得流场信息进行能谱分析来获取涡旋的脱落频率,并进一步使用正交模态分解对流场进行分析,给出了流场主要拟序结构及其能量与转速比的变化趋势。发现圆柱旋转改变圆柱尾流结构,使尾迹尺度变小。在旋转速度比0≤α≤2.0时,存在明显的周期性涡旋脱落,并且涡旋脱落的频率有逐渐升高的趋势;而且当转速比2.0<α≤5.0时尾迹流场的周期性减弱,涡旋脱落变得不明显,流场表现出低频、剪切层的区域特征。随着转速变大,涡旋尺度变小。在较高旋转速度比时,流场中能量被重新分布。
