IMECH-IR

The impact of relative humidity on the nanoindentation relaxation in calcium silicate hydrates

2026-10-13T11:47:47Z

Title: The impact of relative humidity on the nanoindentation relaxation in calcium silicate hydrates Authors: Chen Z(陈召); Frech-Baronet J; Tran H; Sorelli L Description:

Despite extensive research efforts, understanding the time-dependent behavior of concrete remains an enigma due to the complex nature of cement microstructure. In this study, the statistical nanoindentation was employed to investigate the influence of relative humidity (RH) on the relaxation behavior of calcium silicate hydrates (C-S-H) in a cement paste. Our experiments, performed at RH levels of 33 % and 86 %, revealed significant enhancements in both the indentation modulus and hardness of the C-S-H as RH increased. Remarkably, the internal water exerted a significant influence on the asymptotic relaxation behavior, displaying a clear power-law fashion. Further analysis identified the presence of short- and long-term viscoelastic behaviors within the C-S-H, distinguished by a transition observed within the initial seconds. These findings advance the understanding of nanoscale mechanisms driving concrete creep under different humidity conditions.

Flow and Leakage Characteristics in Sealing Chamber of a Variable Geometry Hypersonic Inlet

2026-10-13T07:16:43Z

Title: Flow and Leakage Characteristics in Sealing Chamber of a Variable Geometry Hypersonic Inlet Authors: Xia F; Sun B; Yu JY; Yue LJ(岳连捷); Gao Y; Dai CL Description:

When the variable geometry hypersonic inlet is sealed with ceramic wafers, the cavity flows inside the sealing chamber can be affected by the boundary layer near the side wall. To study the influence of the boundary layer thickness near the side wall on the flow and leakage characteristics in sealing chamber, the numerical calculation of the cavity flow in the sealing chamber under different inflow boundary layer thicknesses is carried out. The results show that three-dimensional cavity flow structures are close to being asymmetric, and the entrance pressure of the leakage path can also be affected by asymmetry; with the increase of the thickness of the boundary layer, the pressure at the cavity floor and the seal entrance decreases. Finally, the existing leakage prediction model is modified according to the distribution rule of the cavity floor and the flow properties in the leakage path.

Advances and perspectives on water imbibition behaviours in shales

2026-10-09T08:27:22Z

Title: Advances and perspectives on water imbibition behaviours in shales Authors: Yang X; Shen WJ(沈伟军); Wang XY; Li N; Chen HC Description:

The characteristically low flowback recovery in shale reservoirs stems from spontaneous imbibition, a governing mechanism for fluid retention and hydrocarbon production. Despite extensive research, the fundamental processes underlying aqueous-phase transport in shales remain poorly understood. This review synthesises recent findings by characterising imbibition as a dynamic, cross-scale transport phenomenon driven by the coupling of capillary suction, chemical potential gradients and clay hydration. Unlike traditional static descriptions of this process, this review highlight how imbibition induces continuous pore-network evolution via hydration-triggered microfracture propagation and mineral-scale blockage. Geological attributes, fluid chemistry and operational parameters are systematically evaluated. We further examine the methodological transition from macroscopic monitoring to in situ visualisation, and from classical analytical solutions to multiphysics numerical frameworks. Lastly, we conclude by identifying critical knowledge gaps and outlining future perspectives in high-pressure high-temperature in situ measurements, multiscale predictive correlations and intelligent fluid systems.

Pore-scale modeling of gas–water two-phase flow in porous gas reservoirs

2026-10-09T06:42:22Z

Title: Pore-scale modeling of gas–water two-phase flow in porous gas reservoirs Authors: Cheng MH; Shen WJ(沈伟军); Ma TR; Chen FJ; Wang XY; Yang X; Jing Y Description:

Porous gas reservoirs are abundant in reserves and represent a significant proportion of discovered gas reservoirs worldwide. During the middle to late stages of development, these reservoirs often face the risk of water invasion, which reduces displacement efficiency and gas recovery rates. However, the gas-water two-phase flow behavior in porous media remains a persistent challenge. To address this issue, a pore-scale gas-water two-phase flow model was established by coupling fluid flow equations with two-phase interfacial transport equations. Using micro-computed tomography technology, a digital core model representative of a porous gas reservoir was reconstructed. The gas-water distribution and migration characteristics were simulated during both the gas-driven water accumulation stage and the water-invasion depletion extraction stage. The effects of injection rate, wettability (contact angle), and interfacial tension on flow behavior and displacement efficiency were analyzed. The results show that wettability governs the two-phase distribution: while water displaces gas along pore walls under hydrophilic conditions, it occupies pore centers under hydrophobic conditions, thereby increasing flow resistance. Increasing the injection rate significantly enhances the driving force and substantially improves gas recovery. In contrast, higher interfacial tension strengthens capillary forces, leading to greater gas retention and reduced ultimate recovery. These results provide an important theoretical foundation and key technical support for understanding gas-water seepage mechanisms in porous gas reservoirs, predicting development dynamics, and formulating rational development strategies.

Closed‑Loop Risk Warning and Quantitative Grading for Shale Gas Hydraulic Fracturing: An Integrated Real‑Time Analytics and Deep Learning Framework

2026-10-09T06:39:23Z

Title: Closed‑Loop Risk Warning and Quantitative Grading for Shale Gas Hydraulic Fracturing: An Integrated Real‑Time Analytics and Deep Learning Framework Authors: Cui HZ; Liu ZY; Han LL; Duan GF; Hou LD; Shen WJ(沈伟军); Xie K; Suo Y; Li KL Description:

During shale gas horizontal well hydraulic fracturing construction, the real-time prediction of wellhead construction pressure and the early identification of risks are crucial for ensuring construction safety and enhancing fracturing efficiency. This study proposes an integrated early risk warning framework featuring three core functions: real-time wellhead construction pressure prediction, early construction risk warning, and classification of frac-hit risk level. The framework employs a Temporal convolutional network-Long short term memory (TCN-LSTM) hybrid model combined with transfer learning strategies to construct a real-time wellhead construction pressure prediction model. This enables high-precision forecasting of future wellhead construction pressures for new wells, achieving an accuracy rate of 97.92%, which significantly outperforms traditional models (with an accuracy improvement of 7.63%-8.81%). The average inference latency is 39.35 ms. Based on this, a multi-head self-attention mechanism is introduced to construct a TCN-LSTM-Attention hybrid model. This achieves early warning identification of two critical risks during fracturing construction: frac-hit and water hammer, with an overall recognition accuracy of 93.6%. Furthermore, to quantify the severity of frac-hit risks, a classification method based on the Gramian Angular Field and ConvNeXt network was introduced, enabling the grading of identified frac-hit risks. Experimental results based on 197 fracturing stages from eight horizontal wells in the Luzhou block of the Sichuan Basin show that the proposed model exhibits good engineering applicability and real-time performance, providing effective technical support for on-site intelligent fracturing decision making.

用于铅衣支撑的柔性外骨骼背架

2026-09-30T03:13:34Z

Title: 用于铅衣支撑的柔性外骨骼背架 Authors: 苏业旺; 郭亮; 王星泉; 胡济海 Description: 本发明涉及医疗器械领域，提供一种用于铅衣支撑的柔性外骨骼背架，包括垫肩结构、柔性杆、仿脊椎结构和连接部件，两个垫肩结构通过支撑横杆连接，支撑横杆的长度方向的中间位置向下连接有支撑竖杆；仿脊椎结构包括套筒和翼展，翼展连接在套筒的两侧，仿脊椎结构通过套筒套在柔性杆上，柔性杆的上端与支撑竖杆连接，柔性杆的下端与连接部件连接，连接部件用于与下肢外骨骼转动连接。本发明采用柔性杆作为背架承重的主体结构，并在柔性杆上增加带展翼的仿脊椎结构，保证了支撑柔韧性，同时增加与人体背部和铅衣接触面积；此外，还可与下肢外骨骼连接，将铅衣的重量传递到地面，减轻医务工作者的身体负重。

一种低功耗地外天体原位增材制造方法和3D打印粘结剂

2026-09-30T03:13:33Z

Title: 一种低功耗地外天体原位增材制造方法和3D打印粘结剂 Authors: 王海瑞; 李凯; 姜恒; 姚海龙; 刘屹东; 闵永刚 Description: 本发明公开了一种低功耗地外天体原位增材制造方法和3D打印粘结剂，属于航天技术领域；该方法包括在地球上提前完成高分子聚合物和发泡剂的制备、在地外天体用其土壤作为该地外天体3D打印的土壤基体、并且在地外天体用包括地球上携带的高压气体作为输运3D打印泡沫粘结剂的气体；该3D打印粘结剂由地球上携带的高分子聚合物和发泡剂、以及高压气体组成；该发泡剂用于混合高分子聚合物制成3D打印泡沫粘结剂；该高压气体用于为地外天体环境下3D打印泡沫粘结剂提供输运动力。本发明通过在月球表面进行发泡与增材制造的结合，有效减少了火箭去往月球的运输成本，实现快速原位制造轻质结构，满足月球基地建设的材料需求，提供一个较为适合的环境。

一种用于超低轨卫星的吸气式电推力器

2026-09-30T03:13:33Z

Title: 一种用于超低轨卫星的吸气式电推力器 Authors: 罗军; 贺建武; 康琦; 段俐; 黄河激; 马隆飞; 付佳豪 Description: 本发明公开了一种用于超低轨卫星的吸气式电推力器，其特点是：包括流控与贮供系统、低气阻气体隔离‑分配系统、温度自调控射频电离系统、离子光学系统、电中和系统；本发明用于超低轨卫星的吸气式电推力器，通过电离并加速捕获的超低轨大气工质获得较大推力，保证卫星的超低轨道(100～300km)维持，推力范围达到1～35mN，比冲≥3500s，羽流发散半角≤20°；通过提供极少量Xe工质(1％～10％)，显著降低推力器的点火功率和工作功率；通过温度自调控射频电离系统，其射频线圈由微重力热管构成，连接多孔相变储能系统与辐射散热系统，降低热环境对推力器寿命减损的影响。通过低气阻气体隔离‑分配器，保证电推力器获得足够的工质流率维持推力器自持放电，同时隔绝等离子体反流。

一种月球车搭载的月壤原位力学静力触探方法

2026-09-30T03:13:32Z

Title: 一种月球车搭载的月壤原位力学静力触探方法 Authors: 李玉琼; 李娜; 韩宗芳; 应黎坪; 袁征; 吕志远 Description: 本发明涉及了一种月球车搭载的月壤原位力学静力触探方法。一种月球车搭载的月壤原位力学静力触探方法，包括，利用钻进子系统获得钻进动力和旋转扭矩，利用静力触探仪的力学传感器获取月壤的阻力特性数据，利用钻进子系统的旋转剪切月壤产生的旋转扭矩，计算静力触探仪剪切月壤产生的剪切作用力，通过旋转扭矩和剪切作用力的理论模型获取月壤的剪切特性，通过计算机设备基于月壤原位力学静力触探系统获取的数据，构建贯入阻力、旋转扭矩和月壤内聚力c、内摩擦角φ的力学方程，以解译月壤原位力学特性参数。本发明具有小型轻量、低能耗、智能化的特点，突破了车载式静力触探仪的技术瓶颈。

一种红外热成像时空信息融合的无损检测方法

2026-09-30T03:13:32Z

Title: 一种红外热成像时空信息融合的无损检测方法 Authors: 黄先富; 黄晓芙; 袁泉子; 张宏业; 刘战伟 Description: 本发明公开一种红外热成像时空信息融合的无损检测方法，涉及无损检测技术领域，包括：搭建线状激光热源扫描红外热成像无损检测系统；采集动态红外热图像序列；计算分析动态红外热图像序列数据，对采集到的动态红外热图像序列，使用红外热成像时空信息融合的后处理方法进行数据处理，得到带有表面裂纹缺陷的全场热响应图像。本发明不仅能将时空信息融合以得到更高分辨率的数据，在提高计算效率的同时获得更全面、准确的全场热响应特征，而且具有较好的灵活性、更广泛适用性，达到了金属表面缺陷无损检测的目的。