SUMMARY During flight, the wings of many insects undergo considerable shape changes in spanwise and chordwise directions. We determined the origin of spanwise wing deformation by combining measurements on segmental wing stiffness of the blowfly Calliphora vicina in the ventral and dorsal directions with numerical modelling of instantaneous aerodynamic and inertial forces within the stroke cycle using a two-dimensional unsteady blade elementary approach. We completed this approach by an experimental study on the wing's rotational axis during stroke reversal. The wing's local flexural stiffness ranges from 30 to 40 nN m2 near the root, whereas the distal wing parts are highly compliant (0.6 to 2.2 nN m2). Local bending moments during wing flapping peak near the wing root at the beginning of each half stroke due to both aerodynamic and inertial forces, producing a maximum wing tip deflection of up to 46 deg. Blowfly wings store up to 2.30 μJ elastic potential energy that converts into a mean wing deformation power of 27.3 μW. This value equates to approximately 5.9 and 2.3% of the inertial and aerodynamic power requirements for flight in this animal, respectively. Wing elasticity measurements suggest that approximately 20% or 0.46 μJ of elastic potential energy cannot be recovered within each half stroke. Local strain energy increases from tip to root, matching the distribution of the wing's elastic protein resilin, whereas local strain energy density varies little in the spanwise direction. This study demonstrates a source of mechanical energy loss in fly flight owing to spanwise wing bending at the stroke reversals, even in cases in which aerodynamic power exceeds inertial power. Despite lower stiffness estimates, our findings are widely consistent with previous stiffness measurements on insect wings but highlight the relationship between local flexural stiffness, wing deformation power and energy expenditure in flapping insect wings.

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Purpose The flow topology for multi-disciplinary configuration (MULDICON) wing is very complicated and nonlinear at low to high angle of attack (AOA). This paper aims to provide the correlation between the unsteadiness and uncertainties of the flow topology and aerodynamic forces and moments above MULDICON WING at a medium to a higher AOA. Design/methodology/approach The experimental and computational fluid dynamics methods were used to investigate a generic MULDICON wing. During the experiment, the AOA were varied from α = 5° to 30°, whereas yaw angle varies between β = ±20° and Reynolds number between Re = 3.0 × 105 and Re = 4.50 × 105. During the experiments steady-state loading, dynamic loading and flow visualization wind tunnel methods were used. Findings The standard deviation quantified the unsteadiness and uncertainties of flow topology and predicted that they significantly affect the pitching moment (Cm) at medium to higher AOA. A strong correlation between flow topology and Cm was exhibited, and the experiment data was well validated by previous numerical work. The aerodynamic center was not fixed and shifted toward the wing apex when AOA is increasing. For a = 10°, the flow becomes more asymmetric. Power spectral densities plots quantify the flow separation (apex vortex, leading-edge vortex and vortex breakdown) over the MULDICON wing. Originality/value The application and comparison of steady-state and dynamic loading data to quantify the unsteadiness and uncertainties of flow topology above the MULDICON wing.

In the sphere of education, testing and enhancing students' comprehension is not a simple process. This is mirrored in the assessment results, where particular courses have a high failure rate. On the UiTM system, the high failure rate is defined as the proportion of students who fail a subject that exceeds the threshold of 25 percent. Therefore, topics exceeding this limit are deemed incapable of meeting the Academic Quality UiTM objective. In this study, Basic Hydraulic courses is chosen to be a pilot study as the failure rate is high for few semesters. A creative strategy and method of teaching and learning is being proposed to increase students' understanding of the course's content as to overcome the related issue. A smartphone application known as Sahabat Maya Pelajar (SMa2P) has been introduced and integrated into the teaching and learning process. According to the examination records of the Basic Hydraulics course at the Faculty of Civil Engineering at UiTM Johor, the failure rate of this course is decrease. This is shown by comparing results between semesters of 20204 and 20212 which indicate the course failure rate decreased by 22% in the latter semester. Therefore, it is crucial to improve students' performance and comprehension by using digital tools as this platform able to incorporate interactive teaching approaches into classroom activities through smartphone application.