Oil-based drilling fluids possess excellent properties such as shale inhibition, cuttings suspension, and superior lubrication, making them essential in the development of unconventional oil and gas reservoirs.However...Oil-based drilling fluids possess excellent properties such as shale inhibition, cuttings suspension, and superior lubrication, making them essential in the development of unconventional oil and gas reservoirs.However, wellbore instability, caused by the invasion of drilling fluids into shale formations, remains a significant challenge for the safe and efficient extraction of shale oil and gas. This work reports the preparation of mesoporous SiO2nanoparticles with low surface energy, utilized as multifunctional agents to enhance the performance of oil-based drilling fluids aimed at improving wellbore stability. The results indicate that the coating prepared from these nanoparticles exhibit excellent hydrophobicity and antifouling properties, increasing the water contact angle from 32°to 146°and oil contact angle from 24°to134.8°. Additionally, these nanoparticles exhibit exceptional chemical stability and thermal resistance.Incorporating these nanoparticles into oil-based drilling fluids reduced the surface energy of the mud cake from 34.99 to 8.17 m J·m-2and increased the roughness of shale from 0.26 to 2.39 μm. These modifications rendered the mud cake and shale surfaces amphiphobic, effectively mitigating capillary infiltration and delaying the long-term strength degradation of shale in oil-based drilling fluids. After 28days of immersion in oil-based drilling fluid, shale cores treated with MF-SiO2exhibited a 30.5% increase in compressive strength compared to untreated cores. Additionally, these nanoparticles demonstrated the ability to penetrate and seal rock pores, reducing the API filtration volume of the drilling fluid from11.2 to 7.6 m L. This study introduces a novel approach to enhance the development of shale gas and oil resources, offering a promising strategy for wellbore stabilization in oil-based drilling fluid systems.展开更多
Purpose: There have been many studies on the effects of different types of backpacks on posture from a biomechanical perspective and on the center of gravity. Considering the effects of autonomic nervous system activi...Purpose: There have been many studies on the effects of different types of backpacks on posture from a biomechanical perspective and on the center of gravity. Considering the effects of autonomic nervous system activity and mood associated with backpacks in mountaineering and hiking, research is also needed from a psychological perspective. In this study, the effects of adjusting the backpack shoulder stabilizer were preliminarily tested in terms of subjective fatigue and changes in autonomic nervous activity after hiking. Methods: The experimental 15 healthy participants hiked the mountain under two conditions: 1) without adjusting the stabilizer, a feature of the backpack (NAH condition), and 2) with the stabilizer adjusted (AH condition). First, all participants hiked the mountain in the NAH condition, and after a 30-minute break, they began the hike in the AH condition after confirming that a) their heart rate had recovered and b) they were in good physical condition. Results: HR was significantly lower after each hiking session than during the session. RMSSD was significantly lower pre-AH and post-AH than the NAH condition, but there was no significant difference between the NAH condition and either post-NAH or post-AH. Additionally, RMSSD was significantly lower in the AH condition than pre-AH or post-AH. The shoulders and back were significantly more burdened in the NAH condition than in the AH condition. The pleasure level was significantly higher in the AH condition than in the NAH condition. Conclusion: The results showed that also adjusting the position of the waist belt when adjusting the shoulder stabilizer, which is mainly used for the neck and shoulders, has a significant positive effect on the subjective burden on the upper body and parasympathetic nervous system activity after hiking.展开更多
This study investigates the use of a low-carbon soil stabilizer called SDG,which is made up of granulated blast furnace slag (GGBFS),desulfurization gypsum (DG),and calcium carbide slag (CCS),to solidify the soil.The ...This study investigates the use of a low-carbon soil stabilizer called SDG,which is made up of granulated blast furnace slag (GGBFS),desulfurization gypsum (DG),and calcium carbide slag (CCS),to solidify the soil.The impact of SDG components on the strength and durability of solidified soil was analysed through a series of tests,including unconfined compressive strength,water stability coefficient,water absorption rate,drying-wetting cycles,and shrinkage tests.Furthermore,microstructure characteristics were analysed using X-ray diffraction (XRD) and scanning electron microscopy (SEM).The study shows that the solidified soil has excellent strength and durability when the SDG stabilizer contains 60% GGBGS,10% DG,and 30% CCS.Additionally,increasing the DG content negatively affects the soil's resistance to water.The SDG stabilizer has potential chemical cementitious characteristics and the calcium carbide slag is rich in calcium ions,which undergo an ion exchange reaction with minerals in the soil.These findings offer new ideas for the development of soil stabilizers.展开更多
随着分布式电源渗透率不断上升,多扰动耦合效应持续增强,新型配电网稳定性分析以及优化运行面临着巨大的挑战。对此,该文依据新型配电网节点电压方程建立多扰动耦合等值电路,并基于多扰动耦合等值电路的潮流可解性提出耦合电压稳定约束(...随着分布式电源渗透率不断上升,多扰动耦合效应持续增强,新型配电网稳定性分析以及优化运行面临着巨大的挑战。对此,该文依据新型配电网节点电压方程建立多扰动耦合等值电路,并基于多扰动耦合等值电路的潮流可解性提出耦合电压稳定约束(coupling voltage stability constraint,CVSC),以实现多扰动耦合影响下的电压稳定性量化约束;同时,通过Bonferroni不等式将CVSC和联合机会约束结合,提出耦合电压稳定联合机会约束(coupling voltage stability joint chance constraint,CVS-JCC);进一步,对CVS-JCC进行确定性转化,得到CVS-JCC的解析表达式,并提出考虑CVS-JCC的配电网优化运行方法,以提高配电网安全、稳定、经济运行能力;最后,通过浙江台州某配电网模型进行仿真实验,证明CVS-JCC的有效性以及不同场景下优化运行方法的先进性。展开更多
In order to solve the drifting away of thermal fog droplets during thermal spraying and the incompatibility between fog droplet carrier and conventional com- mercial agro-chemicals, the fog droplet carrier, surfactant...In order to solve the drifting away of thermal fog droplets during thermal spraying and the incompatibility between fog droplet carrier and conventional com- mercial agro-chemicals, the fog droplet carrier, surfactant, condensation nucleus ma- terial and antifreeze, dispersant, thickener and defoamer were screened and assem- bled to develop a thermal fog sedimentation stabilizer in this study, thereby provid- ing technical support for application and promotion of thermal spraying technology in pest and disease control in crops.展开更多
在新型电力系统复杂工况下,以策略表为主体、通过“离线仿真、在线匹配”的预案式频率稳定控制方案存在较高失配风险,甚至因调控失当引发二次冲击,严重威胁电力系统的安全稳定运行。提出一种计及预案式失配冲击的响应驱动频率稳定紧急...在新型电力系统复杂工况下,以策略表为主体、通过“离线仿真、在线匹配”的预案式频率稳定控制方案存在较高失配风险,甚至因调控失当引发二次冲击,严重威胁电力系统的安全稳定运行。提出一种计及预案式失配冲击的响应驱动频率稳定紧急切负荷策略。该策略动作在预案式控制之后,是对预案式控制的有益补充,能够有效提升系统频率稳定性。首先建立了基于系统频率响应(system frequency response,SFR)模型辨识的频率稳定切负荷量计算方法。提出了基于频率稀疏量测的SFR模型辨识方法,在此基础上建立了含稳定控制的SFR模型,根据频率稳定控制目标迭代求解切负荷量。其次,建立了基于Transformer网络的频率控制敏感点挖掘模型,通过分析关键发电机母线节点频率时序值和频率控制敏感点的映射关系,实现响应驱动的频率控制敏感点在线挖掘。最后,按照敏感点排序快速分配控制措施总量,构建频率稳定紧急控制方案。在某实际交直流混联万节点仿真系统验证了所提方法的有效性。展开更多
基金support from the National Natural:Science Foundation of China(NO.52174014)the National Natural Science Foundation Basic Science Center(NO.52288101).
文摘Oil-based drilling fluids possess excellent properties such as shale inhibition, cuttings suspension, and superior lubrication, making them essential in the development of unconventional oil and gas reservoirs.However, wellbore instability, caused by the invasion of drilling fluids into shale formations, remains a significant challenge for the safe and efficient extraction of shale oil and gas. This work reports the preparation of mesoporous SiO2nanoparticles with low surface energy, utilized as multifunctional agents to enhance the performance of oil-based drilling fluids aimed at improving wellbore stability. The results indicate that the coating prepared from these nanoparticles exhibit excellent hydrophobicity and antifouling properties, increasing the water contact angle from 32°to 146°and oil contact angle from 24°to134.8°. Additionally, these nanoparticles exhibit exceptional chemical stability and thermal resistance.Incorporating these nanoparticles into oil-based drilling fluids reduced the surface energy of the mud cake from 34.99 to 8.17 m J·m-2and increased the roughness of shale from 0.26 to 2.39 μm. These modifications rendered the mud cake and shale surfaces amphiphobic, effectively mitigating capillary infiltration and delaying the long-term strength degradation of shale in oil-based drilling fluids. After 28days of immersion in oil-based drilling fluid, shale cores treated with MF-SiO2exhibited a 30.5% increase in compressive strength compared to untreated cores. Additionally, these nanoparticles demonstrated the ability to penetrate and seal rock pores, reducing the API filtration volume of the drilling fluid from11.2 to 7.6 m L. This study introduces a novel approach to enhance the development of shale gas and oil resources, offering a promising strategy for wellbore stabilization in oil-based drilling fluid systems.
文摘Purpose: There have been many studies on the effects of different types of backpacks on posture from a biomechanical perspective and on the center of gravity. Considering the effects of autonomic nervous system activity and mood associated with backpacks in mountaineering and hiking, research is also needed from a psychological perspective. In this study, the effects of adjusting the backpack shoulder stabilizer were preliminarily tested in terms of subjective fatigue and changes in autonomic nervous activity after hiking. Methods: The experimental 15 healthy participants hiked the mountain under two conditions: 1) without adjusting the stabilizer, a feature of the backpack (NAH condition), and 2) with the stabilizer adjusted (AH condition). First, all participants hiked the mountain in the NAH condition, and after a 30-minute break, they began the hike in the AH condition after confirming that a) their heart rate had recovered and b) they were in good physical condition. Results: HR was significantly lower after each hiking session than during the session. RMSSD was significantly lower pre-AH and post-AH than the NAH condition, but there was no significant difference between the NAH condition and either post-NAH or post-AH. Additionally, RMSSD was significantly lower in the AH condition than pre-AH or post-AH. The shoulders and back were significantly more burdened in the NAH condition than in the AH condition. The pleasure level was significantly higher in the AH condition than in the NAH condition. Conclusion: The results showed that also adjusting the position of the waist belt when adjusting the shoulder stabilizer, which is mainly used for the neck and shoulders, has a significant positive effect on the subjective burden on the upper body and parasympathetic nervous system activity after hiking.
基金Funded by the National Key R&D Program of China (No. 2022YFC3803405)the China State Construction Key Laboratory Project (No. ZJXJ-PT-2022-14)。
文摘This study investigates the use of a low-carbon soil stabilizer called SDG,which is made up of granulated blast furnace slag (GGBFS),desulfurization gypsum (DG),and calcium carbide slag (CCS),to solidify the soil.The impact of SDG components on the strength and durability of solidified soil was analysed through a series of tests,including unconfined compressive strength,water stability coefficient,water absorption rate,drying-wetting cycles,and shrinkage tests.Furthermore,microstructure characteristics were analysed using X-ray diffraction (XRD) and scanning electron microscopy (SEM).The study shows that the solidified soil has excellent strength and durability when the SDG stabilizer contains 60% GGBGS,10% DG,and 30% CCS.Additionally,increasing the DG content negatively affects the soil's resistance to water.The SDG stabilizer has potential chemical cementitious characteristics and the calcium carbide slag is rich in calcium ions,which undergo an ion exchange reaction with minerals in the soil.These findings offer new ideas for the development of soil stabilizers.
文摘随着分布式电源渗透率不断上升,多扰动耦合效应持续增强,新型配电网稳定性分析以及优化运行面临着巨大的挑战。对此,该文依据新型配电网节点电压方程建立多扰动耦合等值电路,并基于多扰动耦合等值电路的潮流可解性提出耦合电压稳定约束(coupling voltage stability constraint,CVSC),以实现多扰动耦合影响下的电压稳定性量化约束;同时,通过Bonferroni不等式将CVSC和联合机会约束结合,提出耦合电压稳定联合机会约束(coupling voltage stability joint chance constraint,CVS-JCC);进一步,对CVS-JCC进行确定性转化,得到CVS-JCC的解析表达式,并提出考虑CVS-JCC的配电网优化运行方法,以提高配电网安全、稳定、经济运行能力;最后,通过浙江台州某配电网模型进行仿真实验,证明CVS-JCC的有效性以及不同场景下优化运行方法的先进性。
基金Supported by Anhui Agricultural Science and Technology Innovation Fund(16A1132)Science and Technology Major Project of Anhui Province(15CZZ03132)Special Fund for Talent Development in Anhui Province(13C1109)~~
文摘In order to solve the drifting away of thermal fog droplets during thermal spraying and the incompatibility between fog droplet carrier and conventional com- mercial agro-chemicals, the fog droplet carrier, surfactant, condensation nucleus ma- terial and antifreeze, dispersant, thickener and defoamer were screened and assem- bled to develop a thermal fog sedimentation stabilizer in this study, thereby provid- ing technical support for application and promotion of thermal spraying technology in pest and disease control in crops.
文摘在新型电力系统复杂工况下,以策略表为主体、通过“离线仿真、在线匹配”的预案式频率稳定控制方案存在较高失配风险,甚至因调控失当引发二次冲击,严重威胁电力系统的安全稳定运行。提出一种计及预案式失配冲击的响应驱动频率稳定紧急切负荷策略。该策略动作在预案式控制之后,是对预案式控制的有益补充,能够有效提升系统频率稳定性。首先建立了基于系统频率响应(system frequency response,SFR)模型辨识的频率稳定切负荷量计算方法。提出了基于频率稀疏量测的SFR模型辨识方法,在此基础上建立了含稳定控制的SFR模型,根据频率稳定控制目标迭代求解切负荷量。其次,建立了基于Transformer网络的频率控制敏感点挖掘模型,通过分析关键发电机母线节点频率时序值和频率控制敏感点的映射关系,实现响应驱动的频率控制敏感点在线挖掘。最后,按照敏感点排序快速分配控制措施总量,构建频率稳定紧急控制方案。在某实际交直流混联万节点仿真系统验证了所提方法的有效性。
