Sintering is a critical process in steel production that facilitates the efficient utilization of iron ore resources.However,compared to advanced sintering technologies,China’s sintering methods still exhibit high en...Sintering is a critical process in steel production that facilitates the efficient utilization of iron ore resources.However,compared to advanced sintering technologies,China’s sintering methods still exhibit high energy consumption,with typical solid fuel consumption for sintering of about 55 kg/t.In response,a pellet sintering process has been developed and its behavior has been investigated at sintering bed heights of 750 and 1500 mm.Additionally,a technical and economic comparison with traditional sintering methods has been conducted.The results indicate that at a bed height of 750 mm,the pellet sintering method can significantly reduce solid fuel consumption by approximately 30.82%,dropping from 70.75 to 48.95 kg/t.Additionally,the coke rate decreased from 4.55%to 3.20%,and harmful emissions in the flue gas were also reduced.As the bed height increases to 1500 mm,sintering performance improves even further.The coke rate is reduced to 3.00%,and solid fuel consumption decreases to 41.27 kg/t,approaching the world’s advanced level(≤40 kg/t).Technical and economic analysis also indicates that adopting the pellet sintering process can lower sintering costs by about 2.18 dollars/t.展开更多
Rock residual strength,as an important input parameter,plays an indispensable role in proposing the reasonable and scientific scheme about stope design,underground tunnel excavation and stability evaluation of deep ch...Rock residual strength,as an important input parameter,plays an indispensable role in proposing the reasonable and scientific scheme about stope design,underground tunnel excavation and stability evaluation of deep chambers.Therefore,previous residual strength models of rocks established were reviewed.And corresponding related problems were stated.Subsequently,starting from the effects of bedding and whole life-cycle evolution process,series of triaxial mechanical tests of deep bedded sandstone with five bedding angles were conducted under different confining pressures.Then,six residual strength models considering the effects of bedding and whole life-cycle evolution process were established and evaluated.Finally,a cohesion loss model for determining residual strength of deep bedded sandstone was verified.The results showed that the effects of bedding and whole life-cycle evolution process had both significant influences on the evolution characteristic of residual strength of deep bedded sandstone.Additionally,residual strength parameters:residual cohesion and residual internal friction angle of deep bedded sandstone were not constant,which both significantly changed with increasing bedding angle.Besides,the cohesion loss model was the most suitable for determining and estimating the residual strength of bedded rocks,which could provide more accurate theoretical guidance for the stability control of deep chambers.展开更多
Many phenomena in nature and technology are associated with the filtration of suspensions and colloids in porous media. Two main types of particle deposition,namely, cake filtration at the inlet and deep bed filtratio...Many phenomena in nature and technology are associated with the filtration of suspensions and colloids in porous media. Two main types of particle deposition,namely, cake filtration at the inlet and deep bed filtration throughout the entire porous medium, are studied by different models. A unified approach for the transport and deposition of particles based on the deep bed filtration model is proposed. A variable suspension flow rate, proportional to the number of free pores at the inlet of the porous medium, is considered. To model cake filtration, this flow rate is introduced into the mass balance equation of deep bed filtration. For the cake filtration without deposit erosion,the suspension flow rate decreases to zero, and the suspension does not penetrate deep into the porous medium. In the case of the cake filtration with erosion, the suspension flow rate is nonzero, and the deposit is distributed throughout the entire porous medium. An exact solution is obtained for a constant filtration function. The method of characteristics is used to construct the asymptotics of the concentration front of suspended and retained particles for a filtration function in a general form. Explicit formulae are obtained for a linear filtration function. The properties of these solutions are studied in detail.展开更多
The quantitative determination and evaluation of rock brittleness are crucial for the estimation of excavation efficiency and the improvement of hydraulic fracturing efficiency.Therefore,a“three-stage”triaxial loadi...The quantitative determination and evaluation of rock brittleness are crucial for the estimation of excavation efficiency and the improvement of hydraulic fracturing efficiency.Therefore,a“three-stage”triaxial loading and unloading stress path is designed and proposed.Subsequently,six brittleness indices are selected.In addition,the evolution characteristics of the six brittleness indices selected are characterized based on the bedding effect and the effect of confining pressure.Then,the entropy weight method(EWM)is introduced to assign weight to the six brittleness indices,and the comprehensive brittleness index Bcis defined and evaluated.Next,the new brittleness classification standard is determined,and the brittleness differences between the two stress paths are quantified.Finally,compared with the previous evaluation methods,the rationality of the proposed comprehensive brittleness index Bcis also verified.These results indicate that the proposed brittleness index Bccan reflect the brittle characteristics of deep bedded sandstone from the perspective of the whole life-cycle evolution process.Accordingly,the method proposed seems to offer reliable evaluations of the brittleness of deep bedded sandstone in deep engineering practices,although further validation is necessary.展开更多
In the context of food security,drying is a crucial postharvest process for paddy grain because it significantly impacts the quality of both paddy and rice.To conserve energy during the drying process,deep bed dryers ...In the context of food security,drying is a crucial postharvest process for paddy grain because it significantly impacts the quality of both paddy and rice.To conserve energy during the drying process,deep bed dryers are used as convective dryers that use a combination of ambient airflow and heating,thus relying on airflow,temperature,and relative humidity(RH)as the primary drying parameters.Consequently,an aeration system is necessary so that the drying air can penetrate the thick pile of paddy grain and distribute evenly throughout the drying chamber.This analysis aimed to determine the most optimal aeration system by using computational fluid dynamics(CFD)and the AHP-TOPSIS method.The quantitative and visual analysis of the airflow velocity,pressure,temperature,and RH was conducted using CFD on four different dryer aeration systems models,which were then ranked by preference value using the AHP-TOPSIS method.Model 4,with a sloping floor and circular pipe formation,was found to have the most optimal aeration system(preference value of 0.788)for a paddy grain deep bed dryer prototype.展开更多
Objective: To compare postoperative outcomes of full-bed deep anterior lamellar keratoplasty (DALK) with penetrating keratoplasty (PK) in treating keratoconus. Methods: Seventy-five eyes of 64 patients who received fu...Objective: To compare postoperative outcomes of full-bed deep anterior lamellar keratoplasty (DALK) with penetrating keratoplasty (PK) in treating keratoconus. Methods: Seventy-five eyes of 64 patients who received full-bed DALK and 52 eyes of 51 patients who received PK between June 2000 and August 2010 were included in this retrospective study. Full-bed DALK was performed using Yao's hooking-detaching technique. PK was performed using a standard technique. Intraoperative and postoperative complications, visual acuity, rejection, graft survival, endothelial cell density, corneal sensation recovery, and re-innervation were compared between the two groups. Results: A best correct visual acuity of 0.5 or better was achieved in 90.7% of eyes after full-bed DALK and in 92.3% of eyes after PK (P=0.75). By the fifth postoperative year, graft endothelial cell loss reached 34.6% in the PK group vs. 13.9% in the full-bed DALK group (P<0.001). There were no statistical differences in corneal sensitivity recovery or corneal re-innervation between the groups (P>0.05). Intraoperative microperforation occurred in seven out of 75 (9.3%) eyes with a temporally postoperative double anterior chamber in two eyes in the full-bed DALK group. Postoperative complications in the PK vs. the full-bed DALK groups respectively were: rejection (7.7% vs. 0%, P=0.015), high intraocular pressure (IOP) (46.2% vs. 1.3%, P<0.001), secondary glaucoma (9.6% vs. 0%, P=0.006), complicated cataract (19.2% vs. 0%, P<0.001), and wound dehiscence (9.6% vs. 0%, P=0.006). Conclusions: Both full-bed DALK and PK can offer long-term satisfactory visual outcomes for keratoconus. Graft rejection, secondary glaucoma, complicated cataracts, and constant endothelial cell loss were observed in eyes only after PK.展开更多
The present status of deep sea bed mining technology for polymetallic nodules has been critically examined in light of its history of development the UNCLoS (the United Nation Convention on the Law of the Sea) regime ...The present status of deep sea bed mining technology for polymetallic nodules has been critically examined in light of its history of development the UNCLoS (the United Nation Convention on the Law of the Sea) regime and the current trends in research.The critical technologies have been highlighted and the need for system integration underscored. The deep sea bed environment and the engineering challenge were presented and the necessary features of the deep sea bed mining system for commercial mining was analyzed. The key accomplishments, problems and future bends in research in the development of the mining system are also discussed. Finally, it points out that the technology gaps can be filled by the bine commercial mining is undertaken as a result of market conditions in its favor.展开更多
For deep CBM productivity improvement,a technical concept of conducting multi-well synchronous hydraulic conformance fracturing was proposed based on its geological characteristics.First,a mathematical model for multi...For deep CBM productivity improvement,a technical concept of conducting multi-well synchronous hydraulic conformance fracturing was proposed based on its geological characteristics.First,a mathematical model for multi-fracture induced stress was established by using the boundary element displacement discontinuity method,to simulate the distribution of induced stress field in deep coal beds and analyze the possibility of the formation of complex fracture networks induced by the hydraulic conformance fracturing.Then,the propagation situation of fracture networks interfered by stress and its influencing factors were studied by using the discrete element method.And finally,the feasibility of synchronous hydraulic conformance fracturing technology was verified through tri-axial fracturing experiment and field application.It is shown that by virtue of synchronous hydraulic conformance fracturing technology,stress interference area and strength are increased,so horizontal major stress difference is decreased and even the direction of earth stress is changed regionally,which is conducive to the connection of developed face cleats and butt cleats in coal rocks,so as to form large,efficient and complex fracture networks.Furthermore,the favorable conditions for the formation of complex fracture networks by hydraulic conformance fracturing include lower initial horizontal major stress difference,low Poisson's ratio,short well spacing and low fracturing fluid viscosity and high net pressure inside the fractures.Finally,it is shown from the 3D true physical simulation experiments that by virtue of this synchronous hydraulic conformance fracturing technology,natural fractures in coal rocks can be connected sufficiently,and consequently complex fracture networks composed of hydraulic fractures,face cleats and butt cleats are created.Based on these research results,a set of optimization design method for the synchronous hydraulic conformance fracturing of deep coal beds was proposed.Five vertical wells located in the deep coal beds of North Shizhuang Block in the Southern Qinshui Basin were chosen for the pilot test.It is indicated from fracture monitoring and drainage/production data that the stimulated reservoir volume(SRV)of synchronous hydraulic fractured wells is large and its fracture network is complex;and that compared with the conventionally fractured wells,the synchronous hydraulic fractured well is earlier in gas breakthrough,and higher and more stable in production rates and casing pressure and its regional pressure drop even spreads to the adjacent wells,so that their production rates are remarkably raised.展开更多
激光粉末床熔融(laser powder bed fusion, LPBF)技术作为金属增材制造领域的前沿工艺,已被成功应用于航空航天等高端制造领域。然而多物理场强耦合效应易引发熔池动态失稳,导致制件内部孔隙缺陷频发,严重影响成形质量稳定性。传统监测...激光粉末床熔融(laser powder bed fusion, LPBF)技术作为金属增材制造领域的前沿工艺,已被成功应用于航空航天等高端制造领域。然而多物理场强耦合效应易引发熔池动态失稳,导致制件内部孔隙缺陷频发,严重影响成形质量稳定性。传统监测手段受限于成本高、部署困难等瓶颈,难以满足工业化生产需求。为此,提出声发射-深度学习融合的在线监测与内部质量智能判别方法。研制了基于声发射传感器的LPBF过程在线监测系统,通过工艺过程全周期声发射信号监测揭示声发射信号特征与成形质量间的映射规律,构建了包含逾8万组样本的熔池声发射数据。针对熔池微弱波动特征提取难题,构建了基于自适应傅里叶神经算子(AFNO)的频域特征提取网络和Kolmogorov-Arnold网络(KAN)的高维特征映射分类器,通过多尺度时域特征融合机制解析熔池动态特性,并借助高维流形精确映射高维特征,实现了声发射信号中微弱波动特征的增强表征和高精度质量判别。试验结果表明:研制的监测系统可有效捕获熔池的动态行为,所提方法质量判别精度达97%以上。展开更多
基金financially supported by Huxiang Youth Talent Program of Hunan Province(No.2024RC3008)National Natural Science Foundation China(Nos.52274343 and 52474370)National Key R&D Program of China(Nos.2023YFC3903900 and 2023YFC3903904).
文摘Sintering is a critical process in steel production that facilitates the efficient utilization of iron ore resources.However,compared to advanced sintering technologies,China’s sintering methods still exhibit high energy consumption,with typical solid fuel consumption for sintering of about 55 kg/t.In response,a pellet sintering process has been developed and its behavior has been investigated at sintering bed heights of 750 and 1500 mm.Additionally,a technical and economic comparison with traditional sintering methods has been conducted.The results indicate that at a bed height of 750 mm,the pellet sintering method can significantly reduce solid fuel consumption by approximately 30.82%,dropping from 70.75 to 48.95 kg/t.Additionally,the coke rate decreased from 4.55%to 3.20%,and harmful emissions in the flue gas were also reduced.As the bed height increases to 1500 mm,sintering performance improves even further.The coke rate is reduced to 3.00%,and solid fuel consumption decreases to 41.27 kg/t,approaching the world’s advanced level(≤40 kg/t).Technical and economic analysis also indicates that adopting the pellet sintering process can lower sintering costs by about 2.18 dollars/t.
基金Projects(2024YFC3013801,2022YFC3004602)supported by the National Key R&D Program of ChinaProjects(U23B2093,52034009)supported by the National Natural Science Foundation of China。
文摘Rock residual strength,as an important input parameter,plays an indispensable role in proposing the reasonable and scientific scheme about stope design,underground tunnel excavation and stability evaluation of deep chambers.Therefore,previous residual strength models of rocks established were reviewed.And corresponding related problems were stated.Subsequently,starting from the effects of bedding and whole life-cycle evolution process,series of triaxial mechanical tests of deep bedded sandstone with five bedding angles were conducted under different confining pressures.Then,six residual strength models considering the effects of bedding and whole life-cycle evolution process were established and evaluated.Finally,a cohesion loss model for determining residual strength of deep bedded sandstone was verified.The results showed that the effects of bedding and whole life-cycle evolution process had both significant influences on the evolution characteristic of residual strength of deep bedded sandstone.Additionally,residual strength parameters:residual cohesion and residual internal friction angle of deep bedded sandstone were not constant,which both significantly changed with increasing bedding angle.Besides,the cohesion loss model was the most suitable for determining and estimating the residual strength of bedded rocks,which could provide more accurate theoretical guidance for the stability control of deep chambers.
文摘Many phenomena in nature and technology are associated with the filtration of suspensions and colloids in porous media. Two main types of particle deposition,namely, cake filtration at the inlet and deep bed filtration throughout the entire porous medium, are studied by different models. A unified approach for the transport and deposition of particles based on the deep bed filtration model is proposed. A variable suspension flow rate, proportional to the number of free pores at the inlet of the porous medium, is considered. To model cake filtration, this flow rate is introduced into the mass balance equation of deep bed filtration. For the cake filtration without deposit erosion,the suspension flow rate decreases to zero, and the suspension does not penetrate deep into the porous medium. In the case of the cake filtration with erosion, the suspension flow rate is nonzero, and the deposit is distributed throughout the entire porous medium. An exact solution is obtained for a constant filtration function. The method of characteristics is used to construct the asymptotics of the concentration front of suspended and retained particles for a filtration function in a general form. Explicit formulae are obtained for a linear filtration function. The properties of these solutions are studied in detail.
基金supported by the National Natural Science Foundation of China(Nos.52034009 and 51974319)the Yue Qi Distinguished Scholar Project(No.2020JCB01)。
文摘The quantitative determination and evaluation of rock brittleness are crucial for the estimation of excavation efficiency and the improvement of hydraulic fracturing efficiency.Therefore,a“three-stage”triaxial loading and unloading stress path is designed and proposed.Subsequently,six brittleness indices are selected.In addition,the evolution characteristics of the six brittleness indices selected are characterized based on the bedding effect and the effect of confining pressure.Then,the entropy weight method(EWM)is introduced to assign weight to the six brittleness indices,and the comprehensive brittleness index Bcis defined and evaluated.Next,the new brittleness classification standard is determined,and the brittleness differences between the two stress paths are quantified.Finally,compared with the previous evaluation methods,the rationality of the proposed comprehensive brittleness index Bcis also verified.These results indicate that the proposed brittleness index Bccan reflect the brittle characteristics of deep bedded sandstone from the perspective of the whole life-cycle evolution process.Accordingly,the method proposed seems to offer reliable evaluations of the brittleness of deep bedded sandstone in deep engineering practices,although further validation is necessary.
基金funded by Balai Pembiayaan Pendidikan Tinggi,Kemendikbudristek,and Lembaga Pengelola Dana Pendidikan(LPDP)through the Indonesian Education Scholarship(1083/J5.2.3/BPI.06/10/2021)supported by Prof.Samsul Rizal of the Department of Mechanical and Industrial Engineering of Universitas Syiah Kuala in the application of Ansys software,which was funded by the LPDP and managed by Indonesian Science Fund(RISPRO/KI/B1/TKL/5/15448/2020)。
文摘In the context of food security,drying is a crucial postharvest process for paddy grain because it significantly impacts the quality of both paddy and rice.To conserve energy during the drying process,deep bed dryers are used as convective dryers that use a combination of ambient airflow and heating,thus relying on airflow,temperature,and relative humidity(RH)as the primary drying parameters.Consequently,an aeration system is necessary so that the drying air can penetrate the thick pile of paddy grain and distribute evenly throughout the drying chamber.This analysis aimed to determine the most optimal aeration system by using computational fluid dynamics(CFD)and the AHP-TOPSIS method.The quantitative and visual analysis of the airflow velocity,pressure,temperature,and RH was conducted using CFD on four different dryer aeration systems models,which were then ranked by preference value using the AHP-TOPSIS method.Model 4,with a sloping floor and circular pipe formation,was found to have the most optimal aeration system(preference value of 0.788)for a paddy grain deep bed dryer prototype.
基金Project (No. 2011C13029-2) supported by the Major Program for Science and Technology Research of Zhejiang Province, China
文摘Objective: To compare postoperative outcomes of full-bed deep anterior lamellar keratoplasty (DALK) with penetrating keratoplasty (PK) in treating keratoconus. Methods: Seventy-five eyes of 64 patients who received full-bed DALK and 52 eyes of 51 patients who received PK between June 2000 and August 2010 were included in this retrospective study. Full-bed DALK was performed using Yao's hooking-detaching technique. PK was performed using a standard technique. Intraoperative and postoperative complications, visual acuity, rejection, graft survival, endothelial cell density, corneal sensation recovery, and re-innervation were compared between the two groups. Results: A best correct visual acuity of 0.5 or better was achieved in 90.7% of eyes after full-bed DALK and in 92.3% of eyes after PK (P=0.75). By the fifth postoperative year, graft endothelial cell loss reached 34.6% in the PK group vs. 13.9% in the full-bed DALK group (P<0.001). There were no statistical differences in corneal sensitivity recovery or corneal re-innervation between the groups (P>0.05). Intraoperative microperforation occurred in seven out of 75 (9.3%) eyes with a temporally postoperative double anterior chamber in two eyes in the full-bed DALK group. Postoperative complications in the PK vs. the full-bed DALK groups respectively were: rejection (7.7% vs. 0%, P=0.015), high intraocular pressure (IOP) (46.2% vs. 1.3%, P<0.001), secondary glaucoma (9.6% vs. 0%, P=0.006), complicated cataract (19.2% vs. 0%, P<0.001), and wound dehiscence (9.6% vs. 0%, P=0.006). Conclusions: Both full-bed DALK and PK can offer long-term satisfactory visual outcomes for keratoconus. Graft rejection, secondary glaucoma, complicated cataracts, and constant endothelial cell loss were observed in eyes only after PK.
文摘The present status of deep sea bed mining technology for polymetallic nodules has been critically examined in light of its history of development the UNCLoS (the United Nation Convention on the Law of the Sea) regime and the current trends in research.The critical technologies have been highlighted and the need for system integration underscored. The deep sea bed environment and the engineering challenge were presented and the necessary features of the deep sea bed mining system for commercial mining was analyzed. The key accomplishments, problems and future bends in research in the development of the mining system are also discussed. Finally, it points out that the technology gaps can be filled by the bine commercial mining is undertaken as a result of market conditions in its favor.
基金Project supported by National Science and Technology Major Project“Stimulation Material Development and Well Completion Technology Research”(No.:2011ZX05042-002-001).
文摘For deep CBM productivity improvement,a technical concept of conducting multi-well synchronous hydraulic conformance fracturing was proposed based on its geological characteristics.First,a mathematical model for multi-fracture induced stress was established by using the boundary element displacement discontinuity method,to simulate the distribution of induced stress field in deep coal beds and analyze the possibility of the formation of complex fracture networks induced by the hydraulic conformance fracturing.Then,the propagation situation of fracture networks interfered by stress and its influencing factors were studied by using the discrete element method.And finally,the feasibility of synchronous hydraulic conformance fracturing technology was verified through tri-axial fracturing experiment and field application.It is shown that by virtue of synchronous hydraulic conformance fracturing technology,stress interference area and strength are increased,so horizontal major stress difference is decreased and even the direction of earth stress is changed regionally,which is conducive to the connection of developed face cleats and butt cleats in coal rocks,so as to form large,efficient and complex fracture networks.Furthermore,the favorable conditions for the formation of complex fracture networks by hydraulic conformance fracturing include lower initial horizontal major stress difference,low Poisson's ratio,short well spacing and low fracturing fluid viscosity and high net pressure inside the fractures.Finally,it is shown from the 3D true physical simulation experiments that by virtue of this synchronous hydraulic conformance fracturing technology,natural fractures in coal rocks can be connected sufficiently,and consequently complex fracture networks composed of hydraulic fractures,face cleats and butt cleats are created.Based on these research results,a set of optimization design method for the synchronous hydraulic conformance fracturing of deep coal beds was proposed.Five vertical wells located in the deep coal beds of North Shizhuang Block in the Southern Qinshui Basin were chosen for the pilot test.It is indicated from fracture monitoring and drainage/production data that the stimulated reservoir volume(SRV)of synchronous hydraulic fractured wells is large and its fracture network is complex;and that compared with the conventionally fractured wells,the synchronous hydraulic fractured well is earlier in gas breakthrough,and higher and more stable in production rates and casing pressure and its regional pressure drop even spreads to the adjacent wells,so that their production rates are remarkably raised.
文摘激光粉末床熔融(laser powder bed fusion, LPBF)技术作为金属增材制造领域的前沿工艺,已被成功应用于航空航天等高端制造领域。然而多物理场强耦合效应易引发熔池动态失稳,导致制件内部孔隙缺陷频发,严重影响成形质量稳定性。传统监测手段受限于成本高、部署困难等瓶颈,难以满足工业化生产需求。为此,提出声发射-深度学习融合的在线监测与内部质量智能判别方法。研制了基于声发射传感器的LPBF过程在线监测系统,通过工艺过程全周期声发射信号监测揭示声发射信号特征与成形质量间的映射规律,构建了包含逾8万组样本的熔池声发射数据。针对熔池微弱波动特征提取难题,构建了基于自适应傅里叶神经算子(AFNO)的频域特征提取网络和Kolmogorov-Arnold网络(KAN)的高维特征映射分类器,通过多尺度时域特征融合机制解析熔池动态特性,并借助高维流形精确映射高维特征,实现了声发射信号中微弱波动特征的增强表征和高精度质量判别。试验结果表明:研制的监测系统可有效捕获熔池的动态行为,所提方法质量判别精度达97%以上。
