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The purpose of this paper is to investigate time-optimal control problems for multiple unmanned aerial vehicle (UAV) systems to achieve predefined flying shape.

Two time-optimal protocols are proposed for the situations with or without human control input, respectively. Then, Pontryagin’s minimum principle approach is applied to deal with the time-optimal control problems for UAV systems, where the cost function, the initial and terminal conditions are given in advance. Moreover, necessary conditions are derived to ensure that the given performance index is optimal.

The effectiveness of the obtained time-optimal control protocols is verified by two contrastive numerical simulation examples. Consequently, the proposed protocols can successfully achieve the prescribed flying shape.

This paper proposes a solution to solve the time-optimal control problems for multiple UAV systems to achieve predefined flying shape.

Existing research suggests that organizational learning, jointly implemented by principals and teachers may reduce agency risks and improve school management effectiveness. However, research investigating how this process occurs is lacking. The relationship between school leaders promoting the involvement of teachers in school-wide processes focused on instructional improvement and the coherence characterizing a school's instructional program remains unclear.

The authors identified shared instructional leadership and instructional coherence, as two key variables describing the process of organizational learning and the outcome of agency risk reduction. The authors employed hierarchical linear modeling to test the hypothesis that shared leaderships positively predicts differences among schools in instructional coherence.

Based on a sample of 113 public high schools selected from a U.S. Midwestern state, the results confirm the hypothesis.

This study uses the existing theoretical and empirical findings to interpret the potential relationship between shared leadership and instructional coherence, and validates it through empirical data analysis. The findings expand the understanding of the shared leadership theory. Although the design of this study is strictly based on theoretical and empirical findings, and part of the purpose of the research is to find the reasons why shared leadership seems to be insignificant in some countries and regions, readers should still note that the sample source is American schools. The findings of this study are worth examining with different samples in future studies.

Since the direct relationship between shared leadership and student standardized test scores has been difficult to measure, and in some countries even negative, there is debate about the need for shared leadership. The difficulty of measurement is caused by the diversity of leadership subjects and the complexity of leadership tasks. This study finds out the direct object of shared leadership and the process of exerting its effects, which will expand the understanding of the positive meaning of shared leadership. This will help different countries and regions better identify and play the role of shared leadership.

Based on the combination of organizational learning theory, agency theory and shared leadership theory, the study modeled the process of collaborative organizational learning among principals and teachers. The study employed instructional coherence as a form of structured organizational learning that is a prerequisite for improvement in common measures of student learning such as standardized test scores. Do so provide practical guidance for educators seeking improvement through organizational learning.

Principal instructional leadership and teacher participation in decision-making are conceptualized as shared instructional leadership (SIL) – a management philosophy that positively impacts student academic performance. However, the statistically meaningful relationship between SIL and student performance remains controversial as SIL functioning is influenced by various fundamental school conditions shaped by education policy, including high-stakes accountability, school autonomy and teacher professionalization. The authors examined the relationship between three SIL policy configurations and promising student performance: inclusion, exclusion and insensitive to SIL.

The authors used fuzzy-set qualitative comparative analysis on data obtained from the Program for International Student Assessment (2015) results, including principals' responses to leadership questions and school conditions shaped by policy, and student science scores in 64 countries and areas.

The role of SIL in student performance varied among the three configurations, and the condition of teacher professionalization in the configuration was consistently associated with high student performance.

SIL can create conditions for continued professional development of the teaching workforce in conjunction with school conditions shaped by policy.

A new approach is proposed toward accurately matching any given realistic hardening and softening data from uniaxial tensile test up to failure and moreover, toward bypassing usual tedious implicit trial-and-error iterative procedures in identifying numerous unknown parameters.

Finite strain response features of metals with realistic hardening-to-softening transition effects up to eventual failure are studied for the first time based on the self-consistent elastoplastic J₂-flow model with the logarithmic stress rate. As contrasted with usual approximate and incomplete treatments merely considering certain particular types of hardening effects such as power type hardening, here a novel and explicit approach is proposed to obtain a complete form of the plastic-work-dependent yield strength over the whole hardening and softening range.

A new multi-axial evolution equation for both hardening and softening effects is established in an explicit form. Complete results for the purpose of model validation and prediction are presented for the finite strain responses of monotonic uniaxial stretching up to failure.

New finite strain elastoplastic equations are established with a new history-dependent variable equivalently in place of the usual plastic work. With these equations, a unified and accurate simulation of both gardening and softening effects up to failure is achieved for the first time in an explicit sense without involving usual tedious implicit trial-and-error iterative procedures.

The purpose of this study is to show how gradual strength degradation of metal beams under cyclic bending up to fatigue failure is simulated based on a new elastoplasticity model free of any yield criterion.

A new approach is proposed toward accurately and explicitly prescribing evolution of non-uniform stress distribution on beam cross-section under cyclic bending and, as such, gradual degradation of the bending strength can be directly determined.

Explicit results for the bending response in a whole cyclic process up to fatigue failure are obtained and the fatigue characteristic curve is for the first time simulated directly between the curvature amplitude and the cycle number to failure.

First, explicit and accurate determination of the non-uniform stress distribution on beam cross-section is achieved with asymptotic softening effects. Second, degradation of the bending strength can be directly deduced cycle by cycle. Finally, the relationship between the bending moment and the curvature is calculated using new and efficient numerical algorithms, thus bypassing usual time-consuming calculations with finite element procedures. Numerical results are presented and in good agreement with experimental data.

This paper aims to set social network, which is recently drawing the most attention in the business administration field, as a major dependent variable of political skill. It is because social network plays a very important role in improving the productivity and performance of firms, and, in actuality, many researches have proved that social network greatly contributes to firm performance.

Researches into social network have not yet established that “through what” or “how” social network can be formed and affected.

In this study, the authors attempt to connect social network with political skill, which is a cause variable.

This approach will give us a better understanding on the formation of social networks and its relationship with political skill, and so eventually, such negative recognition about the politics can be viewed from a different sight of angle.

China is now deeply involved in the process of globalization. It confronts conflicts, such as traditions versus modernization, internationalization versus localization, and Chinese values versus. universal values. China is more open to the outside world than ever. The authors’ survey of the Journal of International and Comparative Education Research reveals that Chinese comparative educators are turning the focus of their studies to try new paradigms in the context of globalization.

Using the theoretical frameworks of public diplomacy and public relations, we mapped how the Chinese government has used panda imagery to build its national brand on Twitter and how this ‘panda diplomacy’ has facilitated its para-diplomatic actions. Our findings uncover new attempts by the Chinese government to engage in digital diplomacy. Mobilizing panda imagery on Twitter enhanced friendly relations with foreign political leaders and people and established a friendly and peaceful image of China on Twitter.

The paper aims to identify and analyze passengers’ riding paths for providing better operational support for digital transformation in megacity metro systems.

The authors develop a method to leverage certain passengers’ deterministic riding paths to corroborate other passengers’ uncertain paths. Using Automatic Fare Collection data and train schedules, a witness model is built to recover the actual riding paths for passengers whose paths are unknown otherwise. The identification and analysis of passenger riding paths between three different types of origin–destination) pairs reveal the complexity of passenger path choice.

The results show that passenger path choice modeling is usually characterized by complexity, experience and partial blindness. Some passengers choose paths that are not optimal due to their experience and limited access to overall metro system information. These passengers could be the subject of improved path guidance in light of riding efficiency improved through digital transformation.

This research contributes to the improvement of metro management and operations by leveraging ongoing digital transformation in megacity metro systems. Based on the riding paths and trip chains of a large number of individual passengers identified by the proposed method, metro operation management could prevent risks in areas with concentrated passenger flow in advance, optimally adjust train schedules on a daily basis and deliver real-time riding guidance station by station, which would greatly improve megacity metro systems’ service safety, quality and operational efficacy over time.

A new and explicit form of the elastic strain-energy function for modeling large strain elastic responses of soft solids is constructed based on Hencky's logarithmic strain tensor.

Well-designed invariants of the Hencky strain are introduced for characterizing deformation modes and, furthermore, a new interpolating technique is proposed for combining piecewise splines into a single smooth function.

With this new form and this new technique, objectives in three respects may be achieved for the first time.

First, no adjustable parameters need to be treated. Second, large strain responses for three benchmark modes are derivable in a decoupled sense without involving strongly nonlinear coupling effects. Finally, large strain data may be automatically and accurately matched for three benchmark modes, including uniaxial, equi-biaxial and plane-strain extension. Numerical examples are presented and compared with usual approaches.