87 research outputs found
Institutional diffusion and implementation of internationalization in higher education: A case study of G University
This study sought to provide relevant data and insights that could validate the usefulness of a blended theoretical model of internationalization based on a modified model of van Dijk and Meijerâs internationalization cube with Rogersâ diffusion of innovation theory with the long term of goal of generating a universally applicable theoretical model to help guide other higher education institutions toward successful internationalization. The blended theoretical framework adapted in this study was used to review G Universityâs (GU) policy, support, and implementation dimensions regarding internationalization and illustrate how internationalization at GU fits into the blended theoretical framework. It was also used to identify how key factors facilitate the institutional diffusion and implementation of internationalization at GU.
This study employed a qualitative instrumental case study methodology. Qualitative data were collected from organizational documents, interviews, and field observations and analyzed through the lens of the blended theoretical framework. The findings indicate that GU is located on position five of a possible eight positions on the modified van Dijk and Meijer internationalization cube incorporated with Rogersâ diffusion of innovation theory with the following characteristics: priority policy, ad-hoc support, and random implementation toward internationalization. It was concluded that advancing GUâs position on the internationalization cube would require adjustments to GUâs policy, support, and implementation dimensions
First detection of transverse vertical oscillation during the expansion of coronal loops
In this Letter, we perform a detailed analysis of the M5.5-class eruptive
flare occurring in active region 12929 on 2022 January 20. The eruption of a
hot channel generates a fast coronal mass ejection (CME) and a dome-shaped
extreme-ultraviolet (EUV) wave at speeds of 740860 km s. The CME is
associated with a type II radio burst, implying that the EUV wave is a
fast-mode shock wave. During the impulsive phase, the flare shows
quasi-periodic pulsations (QPPs) in EUV, hard X-ray, and radio wavelengths. The
periods of QPPs range from 18 s to 113 s, indicating that flare energy is
released and nonthermal electrons are accelerated intermittently with multiple
time scales. The interaction between the EUV wave and low-lying adjacent
coronal loops (ACLs) results in contraction, expansion, and transverse vertical
oscillation of ACLs. The speed of contraction in 171, 193, and 211 {\AA} is
higher than that in 304 {\AA}. The periods of oscillation are 253 s and 275 s
in 304 {\AA} and 171 {\AA}, respectively. A new scenario is proposed to explain
the interaction. The equation that interprets the contraction and oscillation
of the overlying coronal loops above a flare core can also interpret the
expansion and oscillation of ACLs, suggesting that the two phenomena are the
same in essence.Comment: 11 pages, 12 figures, accepted for publication in ApJ
Tertiary Regulation of Cascaded Run-of-the-River Hydropower in the Islanded Renewable Power System Considering Multi-Timescale Dynamics
To enable power supply in rural areas and to exploit clean energy, fully
renewable power systems consisting of cascaded run-of-the-river hydropower and
volatile energies such as pv and wind are built around the world. In islanded
operation mode, the primary and secondary frequency control, i.e., hydro
governors and automatic generation control (AGC), ensure the frequency
stability. However, due to limited water storage capacity of run-of-the-river
hydropower and river dynamics constraints, without coordination between the
cascaded plants, the traditional AGC with fixed participation factors cannot
fully exploit the adjustability of cascaded hydropower. When imbalances between
the volatile energy and load occur, load shedding can be inevitable. To address
this issue, this paper proposes a coordinated tertiary control approach by
jointly considering power system dynamics and the river dynamics that couples
the cascaded hydropower plants. The timescales of the power system and river
dynamics are very different. To unify the multi-timescale dynamics to establish
a model predictive controller that coordinates the cascaded plants, the
relation between AGC parameters and turbine discharge over a time interval is
approximated by a data-based second-order polynomial surrogate model. The
cascaded plants are coordinated by optimising AGC participation factors in a
receding-horizon manner, and load shedding is minimised. Simulation of a
real-life system shows a significant improvement in the proposed method in
terms of reducing load shedding.Comment: Submitted to IET Renewable Power Generation; 11 page
Understanding the Lateral Drifting of an Erupting Filament with a Data-constrained Magnetohydrodynamic Simulation
Solar filaments often exhibit rotation and deflection during eruptions, which
would significantly affect the geoeffectiveness of the corresponding coronal
mass ejections (CMEs). Therefore, understanding the mechanisms that lead to
such rotation and lateral displacement of filaments is a great concern to space
weather forecasting. In this paper, we examine an intriguing filament eruption
event observed by the Chinese H{\alpha} Solar Explorer (CHASE) and the Solar
Dynamics Observatory (SDO). The filament, which eventually evolves into a CME,
exhibits significant lateral drifting during its rising. Moreover, the
orientation of the CME flux rope axis deviates from that of the pre-eruptive
filament observed in the source region. To investigate the physical processes
behind these observations, we perform a data-constrained magnetohydrodynamic
(MHD) simulation. Many prominent observational features in the eruption are
reproduced by our numerical model, including the morphology of the eruptive
filament, eruption path, and flare ribbons. The simulation results reveal that
the magnetic reconnection between the flux-rope leg and neighboring low-lying
sheared arcades may be the primary mechanism responsible for the lateral
drifting of the filament material. Such a reconnection geometry leads to
flux-rope footpoint migration and a reconfiguration of its morphology. As a
consequence, the filament material hosted in the flux rope drifts laterally,
and the CME flux rope deviates from the pre-eruptive filament. This finding
underscores the importance of external magnetic reconnection in influencing the
orientation of a flux rope axis during eruption.Comment: 25 pages, 14 figures, Accepted for publication in Ap
Wakeâeffect aware optimal online control of wind farms : an explicit solution
Wake effects impose significant aerodynamic interactions among wind turbines. To improve the wind farm operating performance, practical wind farm online control considering wake effects becomes very important. To achieve online optimal wind farm control while responding to grid demands, this paper proposes a novel optimal wind farm supervisory control (SC) model and its explicit solutions. From the controller modelling perspective, the two major wind farm operating modes, the maximum power point tracking mode and the setâpoint tracking mode, are first analysed and unified in one optimisation model while considering wake effects. In this way, wind farm power production and rotor kinetic energy reserve can be simultaneously considered to conveniently modify the operation mode in response to different grid demands. Aside from controller modelling, the collocation method is first introduced to address the online application problem of such wakeâeffect aware optimal WF control. Although a few optimisation algorithms have been proposed to find the optimum offline, online optimal control is still challenging because of the computational complexity brought by wake model nonâlinearity and nonâconvexity. The proposed collocation method explicitly approximates the optimal solutions to the proposed supervisory control model, through which only a direct algebraic operation is required for online optimal control instead of repeated optimisations. Case studies are carried out on different wind farms under various wind conditions, showing that the wind farm power production potential and releasable power reserve are improved compared to traditional greedy control in both modes. The accuracy of the collocation method is verified. A detailed analysis of the wind farm production capacity under different wind speeds and directions is also provided
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