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Interactions of solar wind dynamic pressure (SWDP) discontinuities with Earth's magnetosphere cause geomagnetic Sudden Commencements (SCs). Typically, positive/negative SCs occur at low latitudes due to enhancements/reductions in SWDP. However, anomalous dawn‐side SCs of opposite polarity were recently reported during the 10 May 2024, superstorm [Nilam et al., 2025, https://doi.org/10.1029/2025GL117032]. This study examines SC responses to positive and negative pressure discontinuities on the May 10 and October 10 storms under similar storm phases and local times. Both events consistently revealed anomalous dawn‐side low latitude SCs opposite to those at other longitudes. We suggest the main impulse of the Disturbance Polar (DP) field extending equatorward as the most likely source. Under highly compressed background magnetosphere conditions, field‐aligned currents associated with DP fields can shift to lower L‐shells, producing such anomalous SCs at dawn‐side low latitudes. These findings provide new insights into dawn‐side magnetosphere–ionosphere coupling during intense storms.

Conventional borehole pressure relief technologies cannot consider roadway anchorage support and pressure relief simultaneously, which is a disadvantage in that the integrity of the rock mass and supporting structure in the shallow surrounding rock anchorage zone is damaged when relieving and transferring stress. Therefore, this study proposes a new “anchorage + pressure relief” collaborative control technology to realize a trade-off between roadway anchorage support and pressure relief and to study its influencing factors. The proposed technology strengthens anchorage using bolt-cable-grouting in the shallow surrounding rock and excavates large-diameter holes for pressure relief in the stress peak zone outside the anchorage zone; both of these can help transfer the stress peak zones of the roadway sides to the deep surrounding rock without destroying the rock mass in the shallow anchorage zone. The stress evolution characteristics of the hole-making diameter, hole-making angle, and dynamic pressure coefficient on the pressure relief effect are analyzed via numerical simulations. A similarity simulation method is used to verify the effectiveness of the numerical simulation results and prove the feasibility of the proposed technology. Field engineering practice suggests that the maximum convergence of the two sides is 115 mm, and the stress of the anchor cable is < 200 kN after pressure relief via the internal hole-making operation. The deformation of the surrounding rock and stress of the anchor cables are within the safety restrictions. The study results help provide a new method and technical means for the continuous large-deformation control of the surrounding rock of the deep soft broken coal roadway under dynamic pressure disturbance.HighlightsProposed new “anchorage + pressure relief” technology to strengthen anchorage using bolt-cable-grouting in shallow surrounding rock and excavate large-diameter holes for pressure relief in the stress peak zone outside the anchorage zoneThe proposed technology transfers the stress peak zone of the roadway sides to the deep surrounding rock without destroying the rock mass in the shallow anchorage zoneCompared with the conventional borehole pressure relief technology, the proposed technology solves the contradiction between roadway anchorage support and pressure reliefStudied the stress evolution characteristics of the hole-making diameter, hole-making angle, and dynamic pressure coefficient on the pressure relief effect

We investigate how the Martian dayside ionospheric structure is modified by crustal magnetic field (CMF) strength and upstream solar wind pressure by analyzing electron density data from the Langmuir Probe and Waves instrument onboard the MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft. We find that the electron density above the exobase is anticorrelated with the ratio of solar wind's normal dynamic pressure (PSW⊥${P}_{\\text{SW}\\perp }$ ) to CMF magnetic pressure (PCMF${P}_{\\text{CMF}}$ ). We also analyze the electron density behavior across different magnetic topologies as a function of PSW⊥/PCMF${P}_{\\text{SW}\\perp }/{P}_{\\text{CMF}}$ . The extremely low electron density in the draped topology relates to ionopause‐like structures. The lower electron density in the closed and open topology under higher PSW⊥/PCMF${P}_{\\text{SW}\\perp }/{P}_{\\text{CMF}}$may be attributed to a downward force, potentially the J × B force in the case of closed topology. This study highlights the complex interplay between solar wind and CMF in influencing the Martian dayside upper ionosphere. Plain Language Summary Mars is unique in the solar system because it lacks a global dipole field like Earth and instead has crustal magnetic fields (CMF, i.e., pockets of magnetic fields unevenly distributed on its surface). Such a magnetic scenario yields a very special picture of the interaction between solar wind (a stream of charged particles from the Sun) and the Martian upper atmosphere. For decades, people have found that the structure of the Martian ionosphere (an ionized layer in its upper atmosphere) can be heavily influenced by solar wind dynamic pressure (ram pressure of the stream of charged particles) and CMF strength, but the physics behind this is unclear. Our results indicate that the competition between the solar wind dynamic pressure and CMF strength can induce electromagnetic force, which affects the electron density in the Martian ionosphere. This study sheds light on the detailed physics of the interaction between solar wind and CMF and its implication for the behaviors of the Martian ionosphere. Key Points The electron density in the Martian dayside upper ionosphere is anticorrelated with pressure ratio of solar wind to crustal magnetic field The electron density in closed, open, and draped topology behaves differently as a function of this ratio The J × B force may play an important role in the effect of crustal magnetic field and solar wind conditions on the Martian upper ionosphere

Compared with piezoresistive sensors, pressure sensors based on the contact resistance effect are proven to have higher sensitivity and the ability to detect ultra-low pressure, thus attracting extensive research interest in wearable devices and artificial intelligence systems. However, most studies focus on static or low-frequency pressure detection, and there are few reports on high-frequency dynamic pressure detection. Limited by the viscoelasticity of polymers (necessary materials for traditional vibration sensors), the development of vibration sensors with high frequency response remains a great challenge. Here, we report a graphene aerogel-based vibration sensor with higher sensitivity and wider frequency response range (2 Hz–10 kHz) than both conventional piezoresistive and similar sensors. By modulating the microscopic morphology and mechanical properties, the super-elastic graphene aerogels suitable for vibration sensing have been prepared successfully. Meanwhile, the mechanism of the effect of density on the vibration sensor’s sensitivity is studied in detail. On this basis, the sensitivity, signal fidelity and signal-to-noise ratio of the sensor are further improved by optimizing the structure configuration. The developed sensor exhibits remarkable repeatability, excellent stability, high resolution (0.0039 g) and good linearity (non-linearity error < 0.8%) without hysteresis. As demos, the sensor can not only monitor low-frequency physiological signals and motion of the human body, but also respond to the high-frequency vibrations of rotating machines. In addition, the sensor can also detect static pressure. We expect the vibration sensor to meet a wider range of functional needs in wearable devices, smart robots, and industrial equipment.

The novel cross-linking bonding agent, designated as MSC, was meticulously synthesized and subsequently incorporated into the existing bonding agent matrix with the primary objective of significantly enhancing the mechanical properties of composite propellant. This enhancement is achieved by improving the interfacial interactions between the bonding agent and the solid particles, which are crucial for withstanding the various stresses that are produced as a result of combustion loading conditions, as well as fluctuations in environmental conditions, transportation, and handling, all without adversely affecting the ballistic performance of the propellant. In the course of this research endeavour, the substitution of the cross-linking MSC bonding agent for the widely recognized reference bonding agent MAPO has resulted in a notable improvement in the mechanical properties, particularly concerning the strain values that correlate with the stress values. This substitution has effectively doubled the maximum strain value while still maintaining an acceptable maximum stress value, along with a commendable value for Young's modulus within the various propellant formulations being considered. A range of different compositions of composite propellant was systematically investigated in order to accurately measure the linear burning rate and to thoroughly study the effects brought about by the replacement of the MSC bonding agent in lieu of the traditional bonding agent MAPO. The presence of the bonding agent is expected to facilitate a more regular and stable burning process of the composite propellant, particularly under conditions of high dynamic pressure, thereby contributing to more predictable combustion characteristics. Furthermore, various nozzle diameters were employed, each providing distinct burning rates and pressures, thereby enabling the determination of the pressure exponent and the burning rate constant through systematic experimentation and analysis.

To solve control problem of roadways with huge thick roof under the environment of strong dynamic pressure in coal mines, the causes of strong mine pressure behavior in typical dynamic pressure roadway of Caojiatan Coal Mine are analyzed. A control method of cooperative pressure relief by directional roof cutting for roadways with strong dynamic pressure is proposed, and a three-dimensional model test system for this new method is developed. Based on this, the comparative model test of cooperative pressure relief control method and traditional method for dynamic pressure roadway is carried out. The evolution law of stress and displacement of stope and roadway surrounding rock, and the characteristics of overburden movement are compared and analyzed. The control mechanism of cooperative pressure relief method by directional roof cutting for roadways with strong dynamic pressure is clarified, and the control advantage of the new method is verified. Among them, the new method reduces the stope stress by 42.04%, the average stress of the surrounding rock in different parts of the roadway by 20.72%, and the average deformation of the roadway roof and floor by 53.07%. Based on the model test, the field application of the cooperative pressure relief control method by directional roof cutting is carried out, which verifies the validity of the model test. The monitoring results show that the cooperative pressure relief method reduces the degree of mine pressure behavior in dynamic pressure roadway and effectively controls the deformation of roadway surrounding rock.

The important early declining part of the main phase (MP) of geomagnetic storms in SYM‐H (and Dst) from positive main phase onset (MPO) to 0‐level of SYM‐H was somehow missed in the treatment of the storms. We included the missed part (or revised the storms) by raising the 0‐level of SYM‐H to MPO‐level, and showed that the inclusion is important for most aspects of global space weather. However, what drives the missed part is not yet understood. We take up such a study using data and a SYM‐H model. The relative contributions of the solar wind dynamic pressure P and interplanetary electric field IEFy on the missed part are studied statistically using good quality P and IEFy data available for 116 revised intense storms in 1998–2024. The results reveal that (a) the missed part in majority (62%) of storms is mainly (≥75%) due to positive IEFy; (b) in a small number of storms (12%), it is mainly (≥75%) due to decrease in P; and (c) in the remaining 26% of storms, it is due to both decrease in P and positive IEFy. The SYM‐H model is developed from the existing Dst models and incorporates the delay of SYM‐H response to IEFy turning positive. The model reproduces the combined effect of P and positive IEFy nearly agreeing with SYM‐H data, and illustrates their relative contributions for one storm each in the three groups. In short, the missed positive part in majority of storms seems due to positive IEFy.

The ultra-smooth planarization processing of single crystal sapphire is the basis for the realization of high-performance optoelectronic/micro-electronic devices, and its extremely high hardness and stability bring great challenges to the high-efficiency and high-quality planarization. A cluster magnetorheological global dynamic pressure polishing method was proposed by combining the collective constrained polishing disk of a 3-D microstructure with the reciprocating variable gap between tool and workpiece. Four types of magnetorheological polishing methods were used for comparative experimental study, and a single-factor experiment was conducted on process parameters such as the hole diameter and hole gap in the collective constrained polishing disk and variable gap frequency and amplitude of the workpiece. The results show that the flow field characteristics and the structure degree of the carbonyl iron powders in the processing area can be controlled by the collective constrained polishing disk and the reciprocating variable gap motion of the workpiece. The polishing force of the polishing pad on the workpiece surface is increased. Meanwhile, the extrusion scratch removal of abrasive particles and the stretching reflow update can be realized. Compared with traditional magnetorheological polishing, the material removal rate is increased by 154.6%, and the surface roughness is reduced by 67.1%. The average surface roughness of single crystal sapphire decreases from Ra 5.61 to Ra 0.33 nm within an area of 120 μm × 96 μm after 5-h polishing using the optimized process. The global dynamic pressure formed by the collective constrained polishing disk and the reciprocating variable gap of the workpiece can control the force exerted by the polishing pad on the workpiece surface and improve the polishing efficiency and surface quality.

This study examines the impact of the solar wind dynamic pressure (Pd) on the peak current density and latitude of polar electrojets (PEJs), large-scale field-aligned currents (LSFACs), and small-scale FACs (SSFACs) in various local times, seasons, and hemispheres, using Swarm observations during 2014 to 2020. The different Pd effects with enhanced solar wind mass density (Nsw effect) or with enhanced solar wind velocity (Vsw effect) are differentiated. LSFACs and PEJs show pronounced hemispheric and seasonal differences around noontime, where summer variations are more pronounced than winter, due to higher solar EUV conductivity. Increased Pd typically enhances LSFACs, except at midnight when opposing effects from Nsw and Vsw exert on poleward-side FACs. The impact of Vsw on FACp surpasses that of Nsw mostly except for midnight. In contrast, the Nsw impacts on equatorward-side FACs and SSFACs are mostly stronger than the Vsw effect except for the noontime. PEJs strengthen with increasing Vsw effects more efficiently than with increasing Nsw effects. Additionally, a higher Pd shifts PEJs and SSFACs equatorward, with Vsw effects being more prominent than Nsw effects, except for midnight SSFACs.

This research presents a numerical simulation methodology for optimizing circular composite overlays’ dimensions and pressure characteristics with orthotropic mechanical properties, specifically, for metal conduits with temperature-dependent elastoplastic behavior. The primary objective of the proposed method is to prevent crack propagation during pressure surges from operational to critical levels. This study examines the “Beineu-Bozoy-Shymkent” steel gas conduit, examining its performance across a temperature range of −40 to +50°C. This work builds on prior research on extended avalanche destruction in steel gas conduits and crack propagation prevention techniques. The analysis was conducted using a dynamic finite-element approach with the ANSYS-19.2/Explicit Dynamics software. Simulations of unprotected conduits revealed that increasing gas-dynamic pressure can convert a partial-depth crack into a through-crack, extending longitudinally to approximately seven times its initial length. Notably, at T = +50°C, the developed crack length was 1.2% longer than that at T = −40°C, highlighting the temperature sensitivity of crack progression. The modeling results indicate that crack propagation can be effectively controlled using a circular composite overlay with a thickness between 37.5% and 50% of the crack depth and a length approximately five times that of the initial crack, centered symmetrically over the crack. In addition, preliminary stress analysis indicated that limiting the overlay-induced pressure to 5% of the operational pressure effectively arrested crack growth without generating significant stress concentrations near the overlay boundaries, thereby preventing conduit integrity.