Transport policy research has been developed systematically since the second half of the 20th century, when urban planning and transportation systems became critical components of economic development and urbanization. The field has evolved through a wealth of diverse publications and scholarly contributions. Our comprehensive guide synthesizes the state of the art in 20 major categories of transport policy research, identified based on a data-driven categorization. Each category is represented by a leading expert in the field, providing a rigorous assessment of the state of the art on an area together with an identification of challenges to inform future research and policymaking. Aggregated analysis reveals six major trends in policy research, namely: Adaptability, Network Integration, Sustainability, Wireless Connectivity, Equity, and Resilience — combined to form the word ANSWER, with each component being crucial to understanding and addressing the field's multifaceted challenges. Our guide aims to provide answers to pressing challenges and serve as an essential, accessible reference regarding transport policy research for academics, policymakers, and industry stakeholders alike.

The present study explores the possibility of replacing blast furnace slag (BFS) with coal fly ash (FA) to produce alkali-activated material (AAM) concrete with hybrid precursors. With an increased FA replacement ratio, the reaction kinetics, fresh and hardened properties of AAM mixtures have been investigated. The retardation effect on the reaction kinetics with an increased FA content has been observed, which not only extended the induction period along with the heat flow evolution but also reduced the cumulative heat release up to 24 h. Spherical FA particles can provide a ball-bearing effect to improve the workability of the hybrid AAM mixtures, while FA also slows down the deterioration of fresh properties since they are less reactive compared to BFS particles. Regarding the strength development, FA results in the reduction at all curing ages in the mixtures with a low silicate modulus (Ms0.25). Similarly, reduction in 1-day compressive strength has been detected in high silicate modulus mixtures (Ms0.5) with FA replacement, while the mixture with 10% FA exhibits the highest compressive strength among Ms0.5 concretes at later curing ages. Bigger capillary pores have been detected in AAM mixtures with an increase in FA content. However, AAM with 10% FA shows the lowest porosity in Ms0.5 mixtures, which is in agreement with the compressive strength results.

To study the influence of bird impact position and impact posture on the transient response of a fan blade, a smooth particle hydrodynamics (SPH) mallard model established by CT scanning was used to simulate the process of a real bird strikes a high-speed rotating fan with five different impact positions and fifteen different impact attitudes according to the relative speed principle. The effect of impact position and attitude on the transient stress and displacement of the fan blade was obtained. Results show that during the impact process, stress concentration is likely to occur in the blade root and the leading edge, these areas are most susceptible to damage and deformation, and the anterior root has greater stress than the posterior root, which is more likely to be damaged. The impact force on the blade and the stress at the blade root and the leading edge are the largest when the bird strikes the 2/6 blade height position. In the Y-135°, Y-270°, Y-315°, Z-135° and Z-315° impact postures, the equivalent stress of the anterior root is the largest. In the Z-135 impact posture, the equivalent stress of the posterior root is the largest, and the displacement of the leading edge is the largest in the Y-270° impact posture. The results of this study have reference value for the design of anti-bird impact and airworthiness evaluation of fan blades in aero-engine.

Bird impact on fan blades poses a serious threat to the operational safety of aircraft engines.In this study, a real bird model of mallard duck was developed using the smooth particle hydrodynamics method based on a CT scan of a mallard duck.The accuracy of the real bird model was verified by comparing the simulation results of the impact on a plate of real bird model and simplified traditional bird model with the results of Wilbeck's tests.The transient impact responses of bird body and fan blade as the bird was striking a static and a rotating fan blade were comparatively analyzed.To study the effect of fan rotational speed on the bird-impact process, 836r/min, 1984r/min, 3344r/min, and 3772r/min were selected as fan rotational speed.To study the effects of impact location on the bird-impact process, 1/6, 2/6, 3/6, 4/6 and 5/6 of the blade height were selected as impact locations.The results show that blade rotation has a direct impact on the number of bird block cuts, the mass of a single bird block, and the number of impacted blades.Without considering the blade rotation conditions, the contact force, blade root stress, and blade leading edge stress are significantly lower than that when the blade rotation conditions are considered, which makes the prediction of blade stress and damage conservative and inadequate for use in the design of blade strength.Therefore, the blade rotation motion should be considered in the study of bird impact.The interaction mode between the bird and blade at 836r/min speed obviously differs from that at other rotational speeds.The kinetic energy of the bird decreases at a rotational speed of 836r/min, and increases at other rotational speeds, and the increment of the kinetic energy of the bird increases with increases in rotational speed.The leading-edge peak stress at 836r/min is greater than that at 1984r/min;at other rotational speeds, the peak stress of the leading edge increases with increases in the rotational speed.The contact force and blade root stress increase with increases in the rotational speed.With increases in the impact height, the contact force, kinetic-energy increment of the bird body, peak stress of the blade root, kinetic energy of the bird body, and the stress on the leading edge of blade all increase first and then decrease under the combined action of the relative velocity of the impact point and twist angle of the blade.The peak stress of the leading edge and the increment of the kinetic energy of the bird are greatest when impact occurs at 3/6 blade height, and the peak stress of the blade root and the contact force are greatest when impact occurs at 4/6 blade height.

The vacuum interrupter is used as the key component of an active DCCB due to its excellent interruption and dielectric recovery characteristics after current zero. The vacuum interrupter can only interrupt the fault currents below the limitation of a critical di/dt and TIV, otherwise it causes a reignition and the interruption failure. In this paper, a detailed active injection DC CB model is developed, considering operation delay of switches, parasitic parameters of switches and thorough control logic. The limitation dielectric strength between the vacuum gap is defined by the cold break down voltage. Based on the numerical modelling, investigation will be performed to see the performance of DC CB with a failure interruption on the first current zero. The simulation results can help to optimize the injection circuit parameters when DC CB has a failure on the first current zero and has to interrupt in the next current zeros. This algorithm will consider predefined threshold of di/dt, chopping current and variable operation time in different scenarios.