The cavity characteristics in liquid-filled containers caused by high-velocity impacts represent an important area of research in hydrodynamic ram phenomena.The dynamic expansion of the cavity induces liquid pressure ...The cavity characteristics in liquid-filled containers caused by high-velocity impacts represent an important area of research in hydrodynamic ram phenomena.The dynamic expansion of the cavity induces liquid pressure variations,potentially causing catastrophic damage to the container.Current studies mainly focus on non-deforming projectiles,such as fragments,with limited exploration of shaped charge jets.In this paper,a uniquely experimental system was designed to record cavity profiles in behind-armor liquid-filled containers subjected to shaped charge jet impacts.The impact process was then numerically reproduced using the explicit simulation program ANSYS LS-DYNA with the Structured Arbitrary Lagrangian-Eulerian(S-ALE)solver.The formation mechanism,along with the dimensional and shape evolution of the cavity was investigated.Additionally,the influence of the impact kinetic energy of the jet on the cavity characteristics was analyzed.The findings reveal that the cavity profile exhibits a conical shape,primarily driven by direct jet impact and inertial effects.The expansion rates of both cavity length and maximum radius increase with jet impact kinetic energy.When the impact kinetic energy is reduced to 28.2 kJ or below,the length-to-diameter ratio of the cavity ultimately stabilizes at approximately 7.展开更多
Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves a...Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves and fragments.To explore the protective effect of polyurea elastomer on LFC,the damage characteristics of polyurea coated liquid-filled container(PLFC)under the combined loading of blast shock wave and fragments were studied experimentally.The microstructure of the polyurea layer was observed by scanning electron microscopy,and the fracture and self-healing phenomena were analyzed.The simulation approach was used to explain the combined blast-and fragments-induced on the PLFC in detail.Finally,the effects of shock wave and fragment alone and in combination on the damage of PLFC were comprehensively compared.Results showed that the polyurea reduces the perforation rate of the fragment to the LFC,and the self-healing phenomenon could also reduce the liquid loss rate inside the container.The polyurea reduces the degree of depression in the center of the LFC,resulting in a decrease in the distance between adjacent fragments penetrating the LFC,and an increase in the probability of transfixion and fracture between holes.Under the close-in blast,the detonation shock wave reached the LFC before the fragment.Polyurea does not all have an enhanced effect on the protection of LFC.The presence of internal water enhances the anti-blast performance of the container,and the hydrodynamic ram(HRAM)formed by the fragment impacting the water aggravated the plastic deformation of the container.The combined action has an enhancement effect on the deformation of the LFC.The depth of the container depression was 27%higher than that of the blast shock wave alone;thus,it cannot be simply summarized as linear superposition.展开更多
The impact of high-velocity penetrators into liquid-filled containers can generate hydrodynamic ram effects,potentially causing catastrophic structural damage to the container.Previous studies have primarily focused o...The impact of high-velocity penetrators into liquid-filled containers can generate hydrodynamic ram effects,potentially causing catastrophic structural damage to the container.Previous studies have primarily focused on undeformed penetrators,such as fragments or bullets,with limited attention directed toward shaped charge jets.This study investigates the penetration characteristics of shaped charge jets impacting behind-armor liquid-filled containers,with particular emphasis on jet-liquid interactions.A theoretical penetration model incorporating material compressibility and jet stretching was developed based on the virtual origin theory.A high-speed imaging experimental system was designed to capture the jet motion within the container.The impact process was numerically reproduced using ANSYS/LSDYNA,and the effects of standoff and overmatch on jet penetration were analyzed.The results reveal that jet stretching induced by increased standoff enhances the penetration velocity of the jet.A proportional relationship between the stretching factor(λ)and the overmatch parameter(I)was identified,withλranging from approximately 1.22 to 1.38 times I across the studied standoff range(80-220 mm).The findings offer a basis for future studies on the pressure distribution in the liquid and the structural response of containers.展开更多
Non-hydrocarbon is one of major inter-compunds produced by the process of microorganism participating in and rebuilding organism.This non-hydrocarbon could clearly and accurately indicate the organic biogenic structur...Non-hydrocarbon is one of major inter-compunds produced by the process of microorganism participating in and rebuilding organism.This non-hydrocarbon could clearly and accurately indicate the organic biogenic structure and the extent of evolution for hydrocarbon.The components of neutral compound containing oxygen in source rocks extract and its GC-MS characteristic were introduced.展开更多
A fiberless seed mutant(fl)was identified in acommercial cotton(Gossypium hirsutum L.)variety Xu-Zhou 142(FL).This phenotype isassociated with lack of fiber cell initiation in theouter integument of the ovule,as wasch...A fiberless seed mutant(fl)was identified in acommercial cotton(Gossypium hirsutum L.)variety Xu-Zhou 142(FL).This phenotype isassociated with lack of fiber cell initiation in theouter integument of the ovule,as wascharacterized by analysis of genes related to展开更多
1 Introduction Multi-metal contained Lead-zinc deposits in northeast Yunnan,China,is located in a joint place of the Circum-Pacific tectonic domain and Tethyan tectonic domain.This joint place is featured by complex g...1 Introduction Multi-metal contained Lead-zinc deposits in northeast Yunnan,China,is located in a joint place of the Circum-Pacific tectonic domain and Tethyan tectonic domain.This joint place is featured by complex geological structure,unique geological characteristic,and multiple lead-zinc mineral deposits,which are discretely and linearly distributed along the cracks of several main fracture zones.Most of the lead-zinc ores were filled into the展开更多
Non-aligned nations began the 10th summit on September 1 in Jakarta to adapt their movement to the post-Cold War era and lift themselves out of the poverty. Indonesian President Suharto opened the summit. Delegates fr...Non-aligned nations began the 10th summit on September 1 in Jakarta to adapt their movement to the post-Cold War era and lift themselves out of the poverty. Indonesian President Suharto opened the summit. Delegates from its 108 members attended the meeting. The summit concluded on September 6 proposed a new approach designed to promote South-South co-operation. The proposal was contained in the final document.展开更多
The development of strawberry fruit, two cultivars-Gelila and Xiaoshi, was systematically studied by anatomical and embryological methods. The growth dynamics of fruit showed that the two cultivars performed similar ...The development of strawberry fruit, two cultivars-Gelila and Xiaoshi, was systematically studied by anatomical and embryological methods. The growth dynamics of fruit showed that the two cultivars performed similar changes with their fresh weight volume and structure, it included the first slow growth stage, the rapid growth stage and the second solw growth stage. The fruit was a typical polyachene with a ovule which belonged to a Poligonum type, the growth process of pollen tube from stigma to embryo sac was clearly observed by flourescence microscopy. Embryo development was similar to that of most dicotyls, and the mature embryo was orthotropous; Endosperm development was a nuclear type, and gradually disappeared with development:Seed coat consisted of 34 layer cells, and pericarp was composed of 68 layer cells which differentiated from ovary wall cell; The structure of receptacle was a typical stem which consisted of epidermis ,cortex and vascular cylinder. With development, the cortex an展开更多
Erratum to：J.Cent.South Univ.（2014）21：3811-3820DOI：10.1007/s11771-014-2366-9The original version of this article unfortunately contained three mistakes.The mistakes are corrected as follows：1）The spelling of th...Erratum to：J.Cent.South Univ.（2014）21：3811-3820DOI：10.1007/s11771-014-2366-9The original version of this article unfortunately contained three mistakes.The mistakes are corrected as follows：1）The spelling of third author is incorrect.The correct name is Jae-Young PYUN.2）The information of corresponding author is incorrect.The correct information should be Goo-Rak KWON,Professor,PhD;Tel/Fax：＋98-711-7264102;E-mail：grkwon@chosun.ac.kr展开更多
超扩展规则是对扩展规则的扩充,基于超扩展规则能够求得任意两个非互补且不相互蕴含的子句所能扩展出极大项集的交集、差集和并集,并将所得结果以EPCCL(each pair of clauses contains complementary literals)理论的形式保存.基于超扩...超扩展规则是对扩展规则的扩充,基于超扩展规则能够求得任意两个非互补且不相互蕴含的子句所能扩展出极大项集的交集、差集和并集,并将所得结果以EPCCL(each pair of clauses contains complementary literals)理论的形式保存.基于超扩展规则的性质,提出一种EPCCL理论编译算法:求交知识编译算法IKCHER(intersection approach to knowledge compilation based on hyper extension rule).该算法适合难解类SAT问题的知识编译,也是一种可并行的知识编译算法.研究了如何实现多个EPCCL理论的求交操作,证明了EPCCL理论的求交过程是可并行执行的,并设计了相应的并行求交算法PIAE(parellel intersection of any number of EPCCL).通过对输入EPCCL理论对应普通子句集的利用,设计了一种高效的并行求交算法imp-PIAE(improvement of PIAE).基于上述算法,还设计了两种并行知识编译算法P-IKCHER(IKCHER with PIAE)和imp P-IKCHER(IKCHER with imp-PIAE),分别采用PIAE并行合并算法和imp-PUAE并行合并算法.最后,通过实验验证了,大部分情况下,IKCHER算法的编译质量是目前为止所有EPCCL理论编译器中最优的,P-IKCHER算法所使用的合并策略并没有起到加速的效果,反而使得编译效率和编译质量有所下降;imp P-IKCHER算法提高了IKCHER算法的编译效率,CPU四核环境下最高可提高2倍.展开更多
The mitigation of blast shock with water has broad application prospects. Understanding the mitigation effects on the reflected overpressure of the explosion shock with water surrounding an explosive in a confined spa...The mitigation of blast shock with water has broad application prospects. Understanding the mitigation effects on the reflected overpressure of the explosion shock with water surrounding an explosive in a confined space is of great significance for military explosives safety applications. To estimate the effects of the parameters on the reflected overpressure of blasted shock wave, a series of experiments were carried out in confined containers with spherical explosives immersed in a certain thickness of water,and numerical simulations were conducted to explore the corresponding mechanisms. The results reveal that the reflected overpressure is abnormally aggravated at a small scaled distance. This aggravation is due to the high impulse of the bulk accelerated water shell converted from the explosion. With increasing scaled distance, the energy will be gradually dissipated. The mitigation effects will appear with the dispersed water phase front impacting at a larger scaled distance, except in the case of a dense water phase state. A critical scaled distance range of 0.7-0.8 m/kg^(1/3) for effective mitigation was found. It is suggested that the scaled distance of space walls should be larger than the critical value for a certain water-to-explosive weight ratio range(5-20).展开更多
Chromium ore fines containing coal (COFCC) can be rapidly heated by microwave to conduct the voluminal reduction, which lays a foundation of getting sponge ferrochromium powders with a lower content of C. Under the co...Chromium ore fines containing coal (COFCC) can be rapidly heated by microwave to conduct the voluminal reduction, which lays a foundation of getting sponge ferrochromium powders with a lower content of C. Under the conditions of COFCC with n(O)-n(C) (molar ratio) as 1.00-0.84 and n(SiO2)-n(CaO) as 1.00-0.39, the samples were heated by 10 kW microwave power to reach the given temperatures and held for different times respectively. The results show that the low-C-Cr ferrochromium metal phase in the reduced materials forms before the high-C-Cr ferrochromium metal phase does. With increasing temperature the C content of ferrochromium metals is in a positive correlation with the content of Cr. The C content of ferrochromium metal in reduced materials is 0-10.07% with an average value of 4.68%. With the increase of holding time the Cr content in ferrochromium metals is in a negative correlation with the content of C, while the content of Fe changes in the contrary way. In the microwave field the kinetic conditions of carburization are closely related with the temperature of microwave heating, holding time and carbon fitting ratio.展开更多
Discrete manufacturing workshops are confronted with problems of processing diverse products and strict real time requirements for data service calculation and manufacturing equipment,which makes it difficult to provi...Discrete manufacturing workshops are confronted with problems of processing diverse products and strict real time requirements for data service calculation and manufacturing equipment,which makes it difficult to provide real time feedback and compensation.In this study,a high-availability,high-performance,and high-concurrency digital twin reference model was constructed to satisfy a large number of manufacturing requirements.A multiterminal real-time interaction model and information aging classification rules for virtual and physical models were established.Moreover,a multiterminal virtual interaction model was proposed,and a generalized distributed computing service digital twinning system was developed.This digital twin system was considered a machine tool box processing line as an actual case.Consequently,a full closed-loop manufacturing process digital twin platform for physical request service,real-time response,and quality information feedback from iterations,which provides case guidance for subsequent factory digital twin systems,was realized.The proposed system can satisfy the requirements of multidevice big data computing services in modern manufacturing plants,as well as multiplatform,low-latency,and high-fidelity information visualization requirements for managers.Thus,this system is expected to play an important role in information factories.展开更多
Pelletization is one of useful processes for the agglomeration of iron ore or concentrates. However, manganese ore fines are mainly agglomerated by sintering due to its high combined water which adversely affects the ...Pelletization is one of useful processes for the agglomeration of iron ore or concentrates. However, manganese ore fines are mainly agglomerated by sintering due to its high combined water which adversely affects the roasting performance of pellets. In this work, high pressure roll grinding(HPRG) process and optimization of temperature elevation system were investigated to improve the strength of fired manganese ore pellets. It is shown that the manganese ore possesses good ballability after being pretreated by HPRG twice, and good green balls were produced under the conditions of blending 2.0% bentonite in the feed, balling for 7 min at 16.00% moisture. High quality roasted pellets with the compressive strength of 2711 N per pellet were manufactured through preheating at 1050 °C for 10 min and firing at 1335 °C for 15 min by controlling the cracks formation. The fired manganese pellets keep the strength by the solid interconnection of recrystallized pyrolusite grains and the binding of manganite liquid phase which filled the pores and clearance among minerals. The product pellets contain high Mn grade and low impurities, and can be used to smelt ferromanganese, which provides a possible way to use imported manganese ore fines containing high combined water to produce high value ferromanganese.展开更多
In recent years,the safety and comfort of road vehicles driving on bridges under crosswinds have attracted more attention due to frequent occurrences of wind-induced disasters.This study focuses on a container truck a...In recent years,the safety and comfort of road vehicles driving on bridges under crosswinds have attracted more attention due to frequent occurrences of wind-induced disasters.This study focuses on a container truck and CRH2 high-speed train as research targets.Wind tunnel experiments are performed to investigate shielding effects of trains on aerodynamic characteristics of trucks.The results show that aerodynamic interference between trains and trucks varies with positions of trains(upstream,downstream)and trucks(upwind,downwind)and numbers of trains.To summarize,whether the train is upstream or downstream of tracks has basically no effect on aerodynamic forces,other than moments,of a truck driving on windward sides of bridges(upwind).In contrast,the presence of trains on the bridge deck has a significant impact on aerodynamic characteristics of a truck driving on leeward sides(downwind)at the same time.The best shielding effect on lateral forces of trucks occurs when the train is located downstream of tracks.Finally,the pressure measuring system shows that only lift forces on trains are affected by trucks,while other forces and moments are primarily affected by adjacent trains.展开更多
基金financial support from the National Natural Science Foundation of China(Grant No.11572159).
文摘The cavity characteristics in liquid-filled containers caused by high-velocity impacts represent an important area of research in hydrodynamic ram phenomena.The dynamic expansion of the cavity induces liquid pressure variations,potentially causing catastrophic damage to the container.Current studies mainly focus on non-deforming projectiles,such as fragments,with limited exploration of shaped charge jets.In this paper,a uniquely experimental system was designed to record cavity profiles in behind-armor liquid-filled containers subjected to shaped charge jet impacts.The impact process was then numerically reproduced using the explicit simulation program ANSYS LS-DYNA with the Structured Arbitrary Lagrangian-Eulerian(S-ALE)solver.The formation mechanism,along with the dimensional and shape evolution of the cavity was investigated.Additionally,the influence of the impact kinetic energy of the jet on the cavity characteristics was analyzed.The findings reveal that the cavity profile exhibits a conical shape,primarily driven by direct jet impact and inertial effects.The expansion rates of both cavity length and maximum radius increase with jet impact kinetic energy.When the impact kinetic energy is reduced to 28.2 kJ or below,the length-to-diameter ratio of the cavity ultimately stabilizes at approximately 7.
基金supported by the National Natural Science Foundation of China(Grant Nos.12102480,52278543 and 51978660)Natural Science Foundation of Jiangsu Province(Grant No.BK20231489)。
文摘Liquid-filled containers(LFC)are widely used to store and transport petroleum,chemical reagents,and other resources.As an important target of military strikes and terrorist bombings,LFC are vulnerable to blast waves and fragments.To explore the protective effect of polyurea elastomer on LFC,the damage characteristics of polyurea coated liquid-filled container(PLFC)under the combined loading of blast shock wave and fragments were studied experimentally.The microstructure of the polyurea layer was observed by scanning electron microscopy,and the fracture and self-healing phenomena were analyzed.The simulation approach was used to explain the combined blast-and fragments-induced on the PLFC in detail.Finally,the effects of shock wave and fragment alone and in combination on the damage of PLFC were comprehensively compared.Results showed that the polyurea reduces the perforation rate of the fragment to the LFC,and the self-healing phenomenon could also reduce the liquid loss rate inside the container.The polyurea reduces the degree of depression in the center of the LFC,resulting in a decrease in the distance between adjacent fragments penetrating the LFC,and an increase in the probability of transfixion and fracture between holes.Under the close-in blast,the detonation shock wave reached the LFC before the fragment.Polyurea does not all have an enhanced effect on the protection of LFC.The presence of internal water enhances the anti-blast performance of the container,and the hydrodynamic ram(HRAM)formed by the fragment impacting the water aggravated the plastic deformation of the container.The combined action has an enhancement effect on the deformation of the LFC.The depth of the container depression was 27%higher than that of the blast shock wave alone;thus,it cannot be simply summarized as linear superposition.
基金the financial support from the National Natural Science Foundation of China(Grant No.11572159)。
文摘The impact of high-velocity penetrators into liquid-filled containers can generate hydrodynamic ram effects,potentially causing catastrophic structural damage to the container.Previous studies have primarily focused on undeformed penetrators,such as fragments or bullets,with limited attention directed toward shaped charge jets.This study investigates the penetration characteristics of shaped charge jets impacting behind-armor liquid-filled containers,with particular emphasis on jet-liquid interactions.A theoretical penetration model incorporating material compressibility and jet stretching was developed based on the virtual origin theory.A high-speed imaging experimental system was designed to capture the jet motion within the container.The impact process was numerically reproduced using ANSYS/LSDYNA,and the effects of standoff and overmatch on jet penetration were analyzed.The results reveal that jet stretching induced by increased standoff enhances the penetration velocity of the jet.A proportional relationship between the stretching factor(λ)and the overmatch parameter(I)was identified,withλranging from approximately 1.22 to 1.38 times I across the studied standoff range(80-220 mm).The findings offer a basis for future studies on the pressure distribution in the liquid and the structural response of containers.
文摘利用FIASCO(Fast Isolation by AFLP Sequences Containing repeats)技术建立拟穴青蟹Scylla paramamosain基因组文库,并与生物素标记的(CA)15寡核苷酸探针杂交,联合磁珠富集法构建拟穴青蟹微卫星富集文库。测序194个阳性菌落,分析其中的150条序列,结果表明:两碱基重复类型占90%以上,其中重复拷贝数在30以上的占27.45%;含微卫星座位189个,其中完美型146个、非完美型28个和复合型15个。设计125对引物扩增一个拟穴青蟹野生群体(含20个个体),其中的19对引物能稳定扩增且片段大小基本符合理论长度。遗传变异分析表明,17个位点表现出高度多态性,16个位点显著偏离Hardy-Weinberg平衡(P<0.05),4组两两位点间存在连锁不平衡现象(P<0.0026,经Bonferroni法校正),7个微卫星位点可能存在无效等位基因。若排除混合微卫星位点的引物对以及扩增位点PIC(polymorphism information content)值在0.5以下的引物对,则13对引物能用于拟穴青蟹群体遗传学等研究。
文摘Non-hydrocarbon is one of major inter-compunds produced by the process of microorganism participating in and rebuilding organism.This non-hydrocarbon could clearly and accurately indicate the organic biogenic structure and the extent of evolution for hydrocarbon.The components of neutral compound containing oxygen in source rocks extract and its GC-MS characteristic were introduced.
文摘A fiberless seed mutant(fl)was identified in acommercial cotton(Gossypium hirsutum L.)variety Xu-Zhou 142(FL).This phenotype isassociated with lack of fiber cell initiation in theouter integument of the ovule,as wascharacterized by analysis of genes related to
文摘1 Introduction Multi-metal contained Lead-zinc deposits in northeast Yunnan,China,is located in a joint place of the Circum-Pacific tectonic domain and Tethyan tectonic domain.This joint place is featured by complex geological structure,unique geological characteristic,and multiple lead-zinc mineral deposits,which are discretely and linearly distributed along the cracks of several main fracture zones.Most of the lead-zinc ores were filled into the
文摘Non-aligned nations began the 10th summit on September 1 in Jakarta to adapt their movement to the post-Cold War era and lift themselves out of the poverty. Indonesian President Suharto opened the summit. Delegates from its 108 members attended the meeting. The summit concluded on September 6 proposed a new approach designed to promote South-South co-operation. The proposal was contained in the final document.
文摘The development of strawberry fruit, two cultivars-Gelila and Xiaoshi, was systematically studied by anatomical and embryological methods. The growth dynamics of fruit showed that the two cultivars performed similar changes with their fresh weight volume and structure, it included the first slow growth stage, the rapid growth stage and the second solw growth stage. The fruit was a typical polyachene with a ovule which belonged to a Poligonum type, the growth process of pollen tube from stigma to embryo sac was clearly observed by flourescence microscopy. Embryo development was similar to that of most dicotyls, and the mature embryo was orthotropous; Endosperm development was a nuclear type, and gradually disappeared with development:Seed coat consisted of 34 layer cells, and pericarp was composed of 68 layer cells which differentiated from ovary wall cell; The structure of receptacle was a typical stem which consisted of epidermis ,cortex and vascular cylinder. With development, the cortex an
文摘Erratum to：J.Cent.South Univ.（2014）21：3811-3820DOI：10.1007/s11771-014-2366-9The original version of this article unfortunately contained three mistakes.The mistakes are corrected as follows：1）The spelling of third author is incorrect.The correct name is Jae-Young PYUN.2）The information of corresponding author is incorrect.The correct information should be Goo-Rak KWON,Professor,PhD;Tel/Fax：＋98-711-7264102;E-mail：grkwon@chosun.ac.kr
文摘超扩展规则是对扩展规则的扩充,基于超扩展规则能够求得任意两个非互补且不相互蕴含的子句所能扩展出极大项集的交集、差集和并集,并将所得结果以EPCCL(each pair of clauses contains complementary literals)理论的形式保存.基于超扩展规则的性质,提出一种EPCCL理论编译算法:求交知识编译算法IKCHER(intersection approach to knowledge compilation based on hyper extension rule).该算法适合难解类SAT问题的知识编译,也是一种可并行的知识编译算法.研究了如何实现多个EPCCL理论的求交操作,证明了EPCCL理论的求交过程是可并行执行的,并设计了相应的并行求交算法PIAE(parellel intersection of any number of EPCCL).通过对输入EPCCL理论对应普通子句集的利用,设计了一种高效的并行求交算法imp-PIAE(improvement of PIAE).基于上述算法,还设计了两种并行知识编译算法P-IKCHER(IKCHER with PIAE)和imp P-IKCHER(IKCHER with imp-PIAE),分别采用PIAE并行合并算法和imp-PUAE并行合并算法.最后,通过实验验证了,大部分情况下,IKCHER算法的编译质量是目前为止所有EPCCL理论编译器中最优的,P-IKCHER算法所使用的合并策略并没有起到加速的效果,反而使得编译效率和编译质量有所下降;imp P-IKCHER算法提高了IKCHER算法的编译效率,CPU四核环境下最高可提高2倍.
基金funded by National Natural Science Foundation of China, grant ID: 11172245。
文摘The mitigation of blast shock with water has broad application prospects. Understanding the mitigation effects on the reflected overpressure of the explosion shock with water surrounding an explosive in a confined space is of great significance for military explosives safety applications. To estimate the effects of the parameters on the reflected overpressure of blasted shock wave, a series of experiments were carried out in confined containers with spherical explosives immersed in a certain thickness of water,and numerical simulations were conducted to explore the corresponding mechanisms. The results reveal that the reflected overpressure is abnormally aggravated at a small scaled distance. This aggravation is due to the high impulse of the bulk accelerated water shell converted from the explosion. With increasing scaled distance, the energy will be gradually dissipated. The mitigation effects will appear with the dispersed water phase front impacting at a larger scaled distance, except in the case of a dense water phase state. A critical scaled distance range of 0.7-0.8 m/kg^(1/3) for effective mitigation was found. It is suggested that the scaled distance of space walls should be larger than the critical value for a certain water-to-explosive weight ratio range(5-20).
基金Project(50474083) supported by the National Natural Science Foundation of ChinaProject supported by the Baoshan Iron & Steel Co. Ltd. of China
文摘Chromium ore fines containing coal (COFCC) can be rapidly heated by microwave to conduct the voluminal reduction, which lays a foundation of getting sponge ferrochromium powders with a lower content of C. Under the conditions of COFCC with n(O)-n(C) (molar ratio) as 1.00-0.84 and n(SiO2)-n(CaO) as 1.00-0.39, the samples were heated by 10 kW microwave power to reach the given temperatures and held for different times respectively. The results show that the low-C-Cr ferrochromium metal phase in the reduced materials forms before the high-C-Cr ferrochromium metal phase does. With increasing temperature the C content of ferrochromium metals is in a positive correlation with the content of Cr. The C content of ferrochromium metal in reduced materials is 0-10.07% with an average value of 4.68%. With the increase of holding time the Cr content in ferrochromium metals is in a negative correlation with the content of C, while the content of Fe changes in the contrary way. In the microwave field the kinetic conditions of carburization are closely related with the temperature of microwave heating, holding time and carbon fitting ratio.
基金Project(51975019)supported by the National Natural Science Foundation of ChinaProject(2019 ZX 04024001)supported by the National Science and Technology Major Project of ChinaProject(Z 201100006720008)supported by the Beijing Science and Technology Plan,China。
文摘Discrete manufacturing workshops are confronted with problems of processing diverse products and strict real time requirements for data service calculation and manufacturing equipment,which makes it difficult to provide real time feedback and compensation.In this study,a high-availability,high-performance,and high-concurrency digital twin reference model was constructed to satisfy a large number of manufacturing requirements.A multiterminal real-time interaction model and information aging classification rules for virtual and physical models were established.Moreover,a multiterminal virtual interaction model was proposed,and a generalized distributed computing service digital twinning system was developed.This digital twin system was considered a machine tool box processing line as an actual case.Consequently,a full closed-loop manufacturing process digital twin platform for physical request service,real-time response,and quality information feedback from iterations,which provides case guidance for subsequent factory digital twin systems,was realized.The proposed system can satisfy the requirements of multidevice big data computing services in modern manufacturing plants,as well as multiplatform,low-latency,and high-fidelity information visualization requirements for managers.Thus,this system is expected to play an important role in information factories.
基金Project(2011GH561685)supported by the China Torch Program
文摘Pelletization is one of useful processes for the agglomeration of iron ore or concentrates. However, manganese ore fines are mainly agglomerated by sintering due to its high combined water which adversely affects the roasting performance of pellets. In this work, high pressure roll grinding(HPRG) process and optimization of temperature elevation system were investigated to improve the strength of fired manganese ore pellets. It is shown that the manganese ore possesses good ballability after being pretreated by HPRG twice, and good green balls were produced under the conditions of blending 2.0% bentonite in the feed, balling for 7 min at 16.00% moisture. High quality roasted pellets with the compressive strength of 2711 N per pellet were manufactured through preheating at 1050 °C for 10 min and firing at 1335 °C for 15 min by controlling the cracks formation. The fired manganese pellets keep the strength by the solid interconnection of recrystallized pyrolusite grains and the binding of manganite liquid phase which filled the pores and clearance among minerals. The product pellets contain high Mn grade and low impurities, and can be used to smelt ferromanganese, which provides a possible way to use imported manganese ore fines containing high combined water to produce high value ferromanganese.
基金Projects(52078504,51822803,51925808,U1934209)supported by the National Natural Science Foundation of ChinaProject(KF2021-05)supported by the State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,China。
文摘In recent years,the safety and comfort of road vehicles driving on bridges under crosswinds have attracted more attention due to frequent occurrences of wind-induced disasters.This study focuses on a container truck and CRH2 high-speed train as research targets.Wind tunnel experiments are performed to investigate shielding effects of trains on aerodynamic characteristics of trucks.The results show that aerodynamic interference between trains and trucks varies with positions of trains(upstream,downstream)and trucks(upwind,downwind)and numbers of trains.To summarize,whether the train is upstream or downstream of tracks has basically no effect on aerodynamic forces,other than moments,of a truck driving on windward sides of bridges(upwind).In contrast,the presence of trains on the bridge deck has a significant impact on aerodynamic characteristics of a truck driving on leeward sides(downwind)at the same time.The best shielding effect on lateral forces of trucks occurs when the train is located downstream of tracks.Finally,the pressure measuring system shows that only lift forces on trains are affected by trucks,while other forces and moments are primarily affected by adjacent trains.
