The essential characteristics of deflagration-to-detonation transition process
Peer-Reviewed Publication
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Deflagration-to-Detonation Transition (DDT) process is the most common technique for obtaining stable detonation propagation. Although the detonation initiation appearances are different, the essential physical characteristic is the same: the local hot spot created by the energy focus. One or more bow shocks created by Mach reflection remain as strong transverse shocks after the detonation front. The corresponding numerical simulations show that the strong transverse shock propagation behavior strongly depends on the location where the hot spot forms. This work provides some fresh new insights into the DDT process, which may improve the understanding of DDT formation mechanisms.
For multi-vehicle networks, Cooperative Positioning (CP) technique has become a promising way to enhance vehicle positioning accuracy. Especially, the CP performance could be further improved by introducing Sensor-Rich Vehicles (SRVs) into CP networks, which is called SRV-aided CP. However, the SRV-aided CP system may split into several sub-clusters that cannot be connected with each other in dense urban environments, in which the sub-clusters with few SRVs will suffer from degradation of CP performance. In this work, a new locally-centralized CP method based on the clustering optimization strategy, aiming to fully utilize potential available information from high precision node, has been proposed.
Safe and feasible path planning is crucial for achieving autonomous navigation of fixed-wing Unmanned Aerial Vehicles (UAVs) in complex environments. However, due to the high-speed flight and complex control requirements of fixed-wing UAVs, ensuring the feasibility and safety of planned paths in complex environments remains challenging. Researchers at Beihang University have developed a feasible path planning algorithm named Closed-loop Radial Ray A* (CL-RaA*). The core components of the CL-RaA* include an adaptive variable-step-size path search and a just-in-time expansion primitive. By integrating these two components and conducting safety checks on the trajectories to be expanded, the CL-RaA* can rapidly generate safe and feasible paths that satisfy the differential constraints of fixed-wing UAVs.
Modern flight control demands faster response, greater adaptability, and resilience against unknowns—challenges traditional control systems struggle to meet. Incremental Nonlinear Dynamic Inversion (INDI) has emerged as a compelling solution, shifting control logic away from models toward real-time measurements. In a sweeping two-part review, researchers chart the path of INDI from its mathematical roots to its growing role inapplications. With its modular structure and built-in robustness, INDI is no longer just an academic concept.
A servicing spacecraft equipped with a compliant flexible rod has emerged as an innovative solution for detumbling defunct satellites, but the contact-induced vibrations of the flexible rod and severe disturbance pose significant challenges to operational accuracy and safety. Despite the extensive research on vibration suppression and detumbling control for tumbling satellites, the combined application of nonlinear energy sink with active varying stiffness (NES-AVS) for flexible rod vibration suppression in servicing spacecraft has yet to be comprehensively studied, and addressing this research gap is crucial as existing methods struggle to achieve both vibration reduction and guaranteed control performance under contact-induced disturbance.
Nowadays, the prevailing of 5G communication era has greatly stimulated a tremendous progress in microwave devices and has also made a demand of more stringent dielectric characteristics. Therefore, it is important to develop ceramics with excellent microwave dielectric properties.Vanadate dielectrics are attracting attention due to their relatively low sintering temperatures. But their large and negative τf values still limit practical applications, just as most of low εr ceramics. Adding those materials with positive τf values into low εr ceramics is an effective method to adjust τf to the near-zero value. However, this method will inevitably pose the decline in the Q×f value. Consequently, one key challenge facing low εr ceramics is how to adjust τf to the near-zero value without deteriorating Q×f.
In the development of laser-driven color converters with simultaneously possessing excellent optical performance and superior heat dissipation, high-brightness laser lighting faces grave challenges. Herein, a reflective sandwich color converter of phosphor‐in‐glass film with sapphire and alumina (sapphire@PiGF@alumina, abbreviated as S@PiGF@A) is designed and prepared by a thermocompression bonding method. Benefiting from the high thermal conductivity and double-sided heat dissipation channels of alumina and sapphire, the S@PiGF@A color converter can withstand high laser power density and produce ultra-high luminescence. Consequently, the optimized S@PiGF@A converter yields white light with an ultrahigh luminous flux of 6749 lm at a laser power density saturation threshold of 47.70W/mm2, which is 2.44 times that of traditional PiGF@alumina color converter (2522 lm@19.53 W/mm2). The findings provide valuable guidelines to design high quality PiGF color converter for high brightness laser-driven white lighting.
Zeolites have high ion exchange capacity and certain radiation resistance. However, their traditional synthesis methods have problems such as high temperature and pressure and difficult control of morphology. Moreover, powdered zeolites are prone to high pressure drop during dynamic adsorption, which limits their practical engineering applications. Therefore, developing spherical zeolites synthesis technology that combines high mechanical strength, excellent radiation resistance and efficient adsorption performance has become a core challenge in the field of radioactive pollution control.
Recent research highlights the transformative impact of precision medicine on breast cancer management. By tailoring treatments to the unique genetic and molecular profiles of individual tumors, precision medicine has significantly improved outcomes for patients across all major breast cancer subtypes. Key innovations, including advanced diagnostics, targeted therapies, and immunotherapy, are reshaping the landscape of breast cancer care.
With the increasing focus on the pursuit-evasion game, the guidance law capturability analysis has been widely studied recently to theoretically assess the performance of different guidance laws and reveal the impact of the physical constraints on capture zones. In a recent study, the capture zones of the continuous and pulsed guidance laws in the pursuit-evasion game are analytically discussed to provide deep insights into the capturability distinction between the continuous guidance law and the pulsed guidance law.