Particle surface characteristics, floc recoverability and fractal structure of alum-kaolin flocs were investigated using in situ particle image velocimetry （PIV） and microbalance with or without humic acid. Experime...Particle surface characteristics, floc recoverability and fractal structure of alum-kaolin flocs were investigated using in situ particle image velocimetry （PIV） and microbalance with or without humic acid. Experimental results indicated that the zeta potential of kaolin particle surface after adsorption of humic acid was related with humic acid concentration and its acid-base buffering capacity. Adsorption of humic acid resulted in more negative electrophoresis on the particle surface. Coagulant dosages for particles to form flocs would increase with increasing humic concentration. PIV was used to evaluate floc structural fragmentation, floc surface erosion as well as recoverability after high shear. It was found that the floc size during the steady phase of growth was small, while the regrowing capability decreased in the presence of humic acid. The recoverability was closely related with floc breakage modes including floc structural fragmentation and floc surface erosion. The fractal dimensions of alum-kaolin flocs by mass-size method based on microbalance would decrease with increasing humic concentration. This study proved that humic acid had adverse influences on the performance of coagulation process.展开更多
Probabilistic Fault Recoverability(FR) property reveals the capability of a system to accommodate faults under admissible input energy constraints in the sense of satisfactory probability. Motivated by the idea of pro...Probabilistic Fault Recoverability(FR) property reveals the capability of a system to accommodate faults under admissible input energy constraints in the sense of satisfactory probability. Motivated by the idea of probabilistic control methods, a class of admissible probability density functions is designed for detailed description of fault parameters, under which several probabilistic FR conditions are established. This significantly enlarges the range of recoverable faults obtained from the deterministic FR analysis. The tradeoffs between the risk of performance degradation and this increased recoverability margin are exactly achieved by allowing a small risk of FR violation. This paper analyzes the probability FR of dynamic systems with switching and interconnection characteristics, and applies the new results to several aircraft models including single longitudinal aircraft dynamic, Highly Maneuverable Technology(HiMAT) vehicle and meta aircraft. Simulation results show the efficiency of the proposed methods based on the comparison between deterministic and probabilistic cases.展开更多
This paper targets the shale oil reservoirs of middle to high maturity in four major basins of China,including the Permian Lucaogou Formation of the Jimsar Sag in the Junggar Basin,the Chang 73 Member of the Triassic ...This paper targets the shale oil reservoirs of middle to high maturity in four major basins of China,including the Permian Lucaogou Formation of the Jimsar Sag in the Junggar Basin,the Chang 73 Member of the Triassic Yanchang Formation in the Longdong area of the Ordos Basin,the Kong 2 Member of the Paleogene Kongdian Formation in Cangdong Sag of the Bohai Bay Basin,and the Qing 1 Member of the Cretaceous Qingshankou Formation in Changling Sag of the Songliao Basin.The key parameters of the shale oil reservoirs in the four basins,such as reservoirs effectiveness,oil content,crude oil movability,and fracability,have been revealed under identical experimental conditions using the same evaluation technical system,on the basis of technique development and integrated application of multi-scale spatial distribution depiction,effective connectivity calculation,movable oil assessment based on the charging effect,and simulation of fracture propagation during reservoir stimulation.This research overcomes insufficient resolutions of conventional analysis approaches and difficulties in quantitative evaluation,develops the evaluation method for resource recoverability of different types of shale oil,and gains insights into different types of shale oil via comparison.The results of experiments and comparative analysis show that there are significant differences in the endowment of continental shale oil resources in the four major basins in China.Among them,the Lucaogou Formation in the Junggar Basin has more effective shale reservoirs,the Chang 73 sub-member of the Ordos Basin has a comparatively good proportion of movable oil and the Kong 2 Member of the Bohai Bay Basin has the best fracability.These results can provide references and basis for choosing development plans and engineering techniques.展开更多
Recoverability of block-sparse signals by convex relaxation methods is considered for the underdetermined linear model. In previous works, some explicit but pessimistic recoverability results which were associated wit...Recoverability of block-sparse signals by convex relaxation methods is considered for the underdetermined linear model. In previous works, some explicit but pessimistic recoverability results which were associated with the dictionary were presented. This paper shows the recoverability of block-sparse signals are associated with the block structure when a random dictionary is given. Several probability inequalities are obtained to show how the recoverability changes along with the block structure parameters, such as the number of nonzero blocks, the block length, the dimension of the measurements and the dimension of the block-sparse representation signal. Also, this paper concludes that if the block-sparse structure can be considered, the recoverability of the signals wil be improved. Numerical examples are given to il ustrate the availability of the presented theoretical results.展开更多
Sustainably managing vehicles at their end-of-life stage(ELVs)presents significant potential forresource recovery,effectively addressing resource scarcity through the closure of the material loop.While ELVs in countri...Sustainably managing vehicles at their end-of-life stage(ELVs)presents significant potential forresource recovery,effectively addressing resource scarcity through the closure of the material loop.While ELVs in countries like Morocco have traditionally been treated as waste rather than secondaryresource material(SRM),they have the potential to reduce reliance on primary materials when usedjudiciously.Despite policymakers aiming for increased resource efficiency in the automobile sector,there is limited research exploring the role of the informal sector in recovering materials and parts fromELVs.This study investigates the ELV processing scenario at Salmia scrap market,recognized as one of Africa’s largest informal markets for ELVs.Using a mass-balance approach,the disposal of sedan cars isexamined,and a conceptual framework illustrating the process flow and interactions among multiplestakeholders is developed.From sampled sedan cars,approximately 7% of aluminum and 76%of iron,by weight,are recovered.These findings contribute to estimating the potential for recycling andrecovering materials from ELVs processed by the informal sector in Morocco.In a standard operationalcontext,estimations suggest that the sector holds substantial potential to recover aluminum and iron by2030.This underscores the importance of formalizing operations and integrating informal players intothe value chain to effectively address resource scarcity within a circular economy.展开更多
Pores are the main accumulation sites and migration pathways for coalbed methane(also referred to as CBM).Pore structure restricts the content and recoverability of CBM from coal reservoirs.In this study,12 representa...Pores are the main accumulation sites and migration pathways for coalbed methane(also referred to as CBM).Pore structure restricts the content and recoverability of CBM from coal reservoirs.In this study,12 representative coal samples with different ash yields that have similar tectonic characteristics and burial depths were collected from different mining areas in the Jiergalangtu and Huolinhe depressions in the Erlian Basin.These samples were used to study the restrictions of ash yield on the characteristics of coal pore structures and the recoverability of CBM through macroscopic and microscopic structure observation,scanning electron microscope observations,vitrinite reflectance tests,low-temperature N2 adsorption,nuclear magnetic resonance(NMR),and micro-computed tomography.The results show that coal reservoirs in the study area vary greatly in ash yield,based on which they can be divided into three types,i.e.,low-ash-content,ash-bearing,and high-ash-content coal reservoirs.In addition,the ash yield has a certain impact on the development of coal pores;coal samples with lower ash yields indicate the presence of well-developed medium-large pores and better connectivity.Ash yield also has a certain impact on the brittleness of coal wherein a lower ash yield implies the development of brittle coal that is more liable to fracture as compared to less brittle samples at the same pressure.Absorbed gas content also varies significantly with ash yield;a low ash yield impacts the gas saturation of coal.Overall,for coal reservoirs in the study area,their porosity,pore diameter,movable fluid porosity,adsorbed gas amount,and recoverability decrease as the ash yield increases.展开更多
The nutritional situation of the elderly is closely related to the occurrence and development of many diseases.How to reduce the damage of surgery,and improve the postoperative survival rate and quality of life in mal...The nutritional situation of the elderly is closely related to the occurrence and development of many diseases.How to reduce the damage of surgery,and improve the postoperative survival rate and quality of life in malnourished elderly patients is very important.Through the elderly malnutrition perioperative risk factors analysis,we make strategies for risk factors of perioperative-related prevention,from preoperative,intraoperative,and postoperative management of patients,to improve the patient’s life.展开更多
Cloud storage,a core component of cloud computing,plays a vital role in the storage and management of data.Electronic Health Records(EHRs),which document users’health information,are typically stored on cloud servers...Cloud storage,a core component of cloud computing,plays a vital role in the storage and management of data.Electronic Health Records(EHRs),which document users’health information,are typically stored on cloud servers.However,users’sensitive data would then become unregulated.In the event of data loss,cloud storage providers might conceal the fact that data has been compromised to protect their reputation and mitigate losses.Ensuring the integrity of data stored in the cloud remains a pressing issue that urgently needs to be addressed.In this paper,we propose a data auditing scheme for cloud-based EHRs that incorporates recoverability and batch auditing,alongside a thorough security and performance evaluation.Our scheme builds upon the indistinguishability-based privacy-preserving auditing approach proposed by Zhou et al.We identify that this scheme is insecure and vulnerable to forgery attacks on data storage proofs.To address these vulnerabilities,we enhanced the auditing process using masking techniques and designed new algorithms to strengthen security.We also provide formal proof of the security of the signature algorithm and the auditing scheme.Furthermore,our results show that our scheme effectively protects user privacy and is resilient against malicious attacks.Experimental results indicate that our scheme is not only secure and efficient but also supports batch auditing of cloud data.Specifically,when auditing 10,000 users,batch auditing reduces computational overhead by 101 s compared to normal auditing.展开更多
In recent years,deep learning has been introduced into the field of Single-pixel imaging(SPI),garnering significant attention.However,conventional networks still exhibit limitations in preserving image details.To addr...In recent years,deep learning has been introduced into the field of Single-pixel imaging(SPI),garnering significant attention.However,conventional networks still exhibit limitations in preserving image details.To address this issue,we integrate Large Kernel Convolution(LKconv)into the U-Net framework,proposing an enhanced network structure named U-LKconv network,which significantly enhances the capability to recover image details even under low sampling conditions.展开更多
Bone-mimicking gradient porous NiTi shape memory alloys(SMAs)are promising for orthopedic im-plants due to their distinctive superelastic functional properties.However,premature plastic deformation in weak areas such ...Bone-mimicking gradient porous NiTi shape memory alloys(SMAs)are promising for orthopedic im-plants due to their distinctive superelastic functional properties.However,premature plastic deformation in weak areas such as thinner struts,nodes,and sharp corners severely deteriorates the superelasticity of gradient porous NiTi SMAs.In this work,we prepared gradient porous NiTi SMAs with a porosity of 50%by additive manufacturing(AM)and achieved a remarkable improvement of superelasticity by a simple solution treatment regime.After solution treatment,phase transformation temperatures dropped signif-icantly,the dislocation density decreased,and partial intergranular Ti-rich precipitates were transferred into the grain.Compared to as-built samples,the strain recovery rate of solution-treated samples was nearly doubled at a pre-strain of 6%(up to 90%),and all obtained a stable recoverable strain of more than 4%.The remarkable superelasticity improvement was attributed to lower phase transformation tem-peratures,fewer dislocations,and the synergistic strengthening effect of intragranular multi-scale Ti-Ni precipitates.Notably,the gradient porous structure played a non-negligible role in both superelasticity deterioration and improvement.The microstructure evolution of the solution-treated central strut after constant 10 cycles and the origin of the stable superelastic response of gradient porous NiTi SMAs were revealed.This work provides an accessible strategy for improving the superelastic performance of gra-dient porous NiTi SMAs and proposes a key strategy for achieving such high-performance architectured materials.展开更多
In the process of stage separation of recoverable liquid launch vehicles,because of the large amount of residual fuel in the storage tanks,the influence of liquid sloshing on separation safety must be considered.Consi...In the process of stage separation of recoverable liquid launch vehicles,because of the large amount of residual fuel in the storage tanks,the influence of liquid sloshing on separation safety must be considered.Considering calculation simplicity and operation practicability,the Moving Pulsating Ball Model(MPBM)of large amplitude liquid sloshing is introduced into the calculation of launch vehicle stage separation.Combining the dynamic equation of the model with the energy relationship during"breathing movement",the formula calculating the force of liquid on the rigid body is derived.Compared with the calculations of commercial CFD calculation software,the accuracy of MPBM model is verified.Then,all the external forces and moments are applied to the rigid body of the stages,so that the translational and rotational dynamic equations of the stages are obtained respectively.According to the relative position of the two stages,the geometric shape of the interstage section and the engine of the second stage,the minimum clearance in the separation process can be decided to guarantee that the separation process is safe.展开更多
The circulating water system is widely used as the cooling system in the process industry,which has the characteristics of high water and power consumption,and its energy consumption level has an important impact on t...The circulating water system is widely used as the cooling system in the process industry,which has the characteristics of high water and power consumption,and its energy consumption level has an important impact on the economic performance of the whole system.Pump network and water turbine network constitute the work network of the circulating water system,that is,the fluid machinery network.Based on the previous studies,this paper proposes a stepwise method to optimize the fluid machinery network,that is,to optimize the network structure by using the recoverable pressure-head curve of the branch,and consider the recovery of adjustable resistance at the valve of each branch,so as to further reduce energy consumption and water consumption.The calculation result of the case shows that the topology structure optimization can further reduce the operation cost and the annual capital cost on the basis of the fixed structure optimization,and the total annualized cost can be reduced by 30.04%.The optimization result of different flow shows that both the pump network and the water turbine network tend to series structure at a low flow rate whereas to parallel structure at a high flow rate.展开更多
The long-term exposure of building structures in coastal areas of our country to corrosive environment will lead to a significant decrease in the seismic performance of structures due to the corrosion of steel bars in...The long-term exposure of building structures in coastal areas of our country to corrosive environment will lead to a significant decrease in the seismic performance of structures due to the corrosion of steel bars in reinforced concrete structures. Starting from the concept of seismic recoverability of building structures, this paper introduces the evaluation method of seismic recoverability of corroded reinforced concrete structures based on functional deterioration, and summarizes the relevant numerical simulation research of corroded reinforced concrete frame structures under the standard design in our country. The results show that steel corrosion in reinforced concrete structures under corrosive environment has a significant impact on the seismic recoverability of the structures. With the increase of steel corrosion degree, the seismic recoverability of the target structures will be significantly reduced. The research results can provide theoretical support and reference for seismic recoverability evaluation of similar structures.展开更多
In the aftermath of the global financial crisis of 2008,China witnessed gradual shrinkage of cities in the Pearl River Delta(PRD).In this study,we introduce the concept of economic resilience to analyse urban growth a...In the aftermath of the global financial crisis of 2008,China witnessed gradual shrinkage of cities in the Pearl River Delta(PRD).In this study,we introduce the concept of economic resilience to analyse urban growth and shrinkage in the context of a rapidly-urbanising region.Multiple regression analysis is performed to explore the determinants of economic resilience in the PRD.By measuring resistance in the shrinking phase and recoverability in the growing phase in a group of cities in the PRD,this study distinguishes four scenarios and investigates their characteristics from a spatial perspective.The results demonstrate that the financial crisis had a severe and asymmetric influence on this area,indicating more than 15%of cities are faced with shrinking.The spatial distribution of economic resilience indicates a centre-periphery pattern,that is,high economic resilience in the inner ring and low economic resilience in the outer ring of the PRD.The service economy is found to play a significant role in promoting urban economic resilience.Results imply that sound economic policies for enhancing resilience:both poor local financial status and a high degree of export concentration adversely impact resistance,while upgrading the manufacturing economy and stimulating of industrial innovation are conducive to improve recoverability.展开更多
An asymmetry power clock,4 phase power clock supplying the power to the DSCRL(dual swing charge recovery logic) adiabatic circuit is presented.It is much simpler than the 6 phase power clock,symmetry power clock,us...An asymmetry power clock,4 phase power clock supplying the power to the DSCRL(dual swing charge recovery logic) adiabatic circuit is presented.It is much simpler than the 6 phase power clock,symmetry power clock,used in the DSCRL adiabatic circuit.Although the 4 phase power clock is simpler,the DSCRL adiabatic circuit still shows good performance and high efficiency of energy transfer and recovery.This conclusion has been proved by the result of the HSPICE simulation using the 0 6μm CMOS technology.展开更多
The study aims at exploring the possibility of using the recovery ability af- ter drought stress-rewatering at vegetative growth stage as the evaluating index in water use efficiency （WUE） of winter wheat varieties....The study aims at exploring the possibility of using the recovery ability af- ter drought stress-rewatering at vegetative growth stage as the evaluating index in water use efficiency （WUE） of winter wheat varieties. ＇Jing 411 ＇, ＇Jinmai 47＇ and their 34 near isogenic lines （NILs） were used as test materials. Semi-automatic rainproof shelter and the percolating pools were used for simulating drought treat- ment. After suffering severe drought stress, winter wheat crops were rewatered at early jointing stage. The biomass accumulation after rewatering was determined as recovery ability index. In the meanwhile, plant height in the end of vegetative growth stage was measured, and WUE of varieties/lines was also determined. Thereafter, the differences in recovery ability, plant height and the population WUE, together with the correlation between recovery ability and population WUE were analyzed, respectively. The results showed that there were significant differences in recovery ability among some varieties/lines. The recovery ability was affected by both geno- type and environment, and the interaction existed in these two factors. Significant differences existed in plant height and population WUE among the 34 NILs along with their parents. There was a significantly positive correlation between recovery ability and plant height of varieties/lines. Recovery ability and plant height were very significantly and positively correlated with population yield WUE respectively. The re- sults indicated that recovery ability after drought stress-rewatering could be used as an evaluating index of population WUE under drought condition.展开更多
After over 10 years'development of coalbed methane(CBM)industry in China,two industrial bases have been built,i.e.,the Qinshui Basin and the Ordos Basin.However,the biggest problem that restricts the high-efficien...After over 10 years'development of coalbed methane(CBM)industry in China,two industrial bases have been built,i.e.,the Qinshui Basin and the Ordos Basin.However,the biggest problem that restricts the high-efficiency development of CBM industry in China is that average single-well gas production rate is low.At present,the production of high-rank CBM accounts for more than 90%of total CBM production in China.In the future,the exploitation field of high-rank CBM resources will focus on the deep and medium reservoirs.The complex CBM occurrence and flow conditions(e.g.different tectonic field,stress field and fracture field)bring great challenges to the adaptability of existing engineering technologies to geological conditions.In this regard,this paper takes the research and practice of high-rank CBM technologies in the Qinshui Basin of PetroChina Huabei Oilfield Company as an example to analyze the“four low”(low effective reserve producing ratio,low remaining producible reserves,low single-well gas production rate and low exploitation profit)CBM exploitation phenomena and discuss the essence of CBM exploitation dialectically.And the following research results were obtained.First,current major problems in CBM exploitation include CBM reserve recoverability,geological difference,engineering technological adaptability and scientific drainage gas recovery.Second,the only way for scientific CBM exploitation is to break through the key bottlenecks under existing technical conditions,including control technology for reserve development,regional selection technology for economic productivity construction,engineering technology suitable for geological characteristics and top-level design technology for scheme preparation.Third,the exploitation practice achievements of high-rank CBM in the Mabidong Block and medium-rank CBM in the Dacheng uplift are realized by breaking the traditional geological cognitions and breaking through the restricted idea that the CBM below 800 m is not suitable to be developed.And it is demonstrated that burial depth is not the limitation condition to determine if CBM can be exploited and medium and deep reservoirs are not the forbidden areas of CBM exploitation.展开更多
There are abundant high-rank coal bed methane(CBM)resources in China,accounting for one third of total CBM resources.Its efficient development and utilization is of great significance to guarantee the national energy ...There are abundant high-rank coal bed methane(CBM)resources in China,accounting for one third of total CBM resources.Its efficient development and utilization is of great significance to guarantee the national energy strategic security,diminish the hidden danger of coal mine production and reduce carbon dioxide emission.In order to solve the"four lows"problem(i.e.,low effective utilization ratio of proved reserves,low productivity targeting ratio,low single-well production rate and low development profit)restricting the development of high-rank CBM industry in China,this paper deeply analyzes the core problems restricting the development of high-rank CBM.Based on this,several new methods of production control,area selection and evaluation are put forward by taking multiple measures,such as paying the same attention on theoretical research and technological research&development,carrying out laboratory research and field test in parallel and conducting large scale construction and benefit development simultaneously.And the following research results are obtained.First,the geological difference between CBM and coal mine,the difference in reserves recoverability,the adaptability of engineering technology and the scientificity of production are the main factors restricting CBM development effect.Second,"Four-element"production control theory,methane-leading en gineering transformation method and methane-leading production control theory are proposed,which provides guidance for the development of a series of technologies for the efficient development of high-rank CBM.Third,in practice,the control degree of quality reserves is increased from 32%to 80%,the success ratio of development wells is increased from 60%to 95%,the average single-well daily gas production of vertical wells is increased by about 1100 m^(3),the drilling cost of horizontal wells is reduced by 50%,and the operation cost per cubic meter of gas is reduced by 24%.In conclusion,the established technology series for the efficient development of high-rank CBM actively promote the efficient CBMdevelopment in the Qinshui Basin.The yearly CBM production of PetroChina Huabei Oilfield Company is expected to reach 20108 m^(3) in the middle of the"14th Five-Year Plan",which promotes the strategic development of CBM industry in China.展开更多
With the deepening of human research on deep space exploration,our research on the soft landing methods of landers has gradually deepened.Adding a buffer and energy-absorbing structure to the leg structure of the land...With the deepening of human research on deep space exploration,our research on the soft landing methods of landers has gradually deepened.Adding a buffer and energy-absorbing structure to the leg structure of the lander has become an effective design solution.Based on the energy-absorbing structure of the leg of the interstellar lander,this paper studies the appearance characteristics of the predatory feet of the Odontodactylus scyllarus.The predatory feet of the Odontodactylus scyllarus can not only hit the prey highly when preying,but also can easily withstand the huge counter-impact force.The predatory feet structure of the Odontodactylus scyllarus,like a symmetrical cone,shows excellent rigidity and energy absorption capacity.Inspired by this discovery,we used SLM technology to design and manufacture two nickel-titanium samples,which respectively show high elasticity,shape memory,and get better energy absorption capacity.This research provides an effective way to design and manufacture high-mechanical energy-absorbing buffer structures using bionic 3D printing technology and nickel-titanium alloys.展开更多
基金supported by the National Natural Science Foundation of China (No. 20721140019, U0773002)the National High Technology Research and Development Program (863) of China (No. 2002AA601120)
文摘Particle surface characteristics, floc recoverability and fractal structure of alum-kaolin flocs were investigated using in situ particle image velocimetry （PIV） and microbalance with or without humic acid. Experimental results indicated that the zeta potential of kaolin particle surface after adsorption of humic acid was related with humic acid concentration and its acid-base buffering capacity. Adsorption of humic acid resulted in more negative electrophoresis on the particle surface. Coagulant dosages for particles to form flocs would increase with increasing humic concentration. PIV was used to evaluate floc structural fragmentation, floc surface erosion as well as recoverability after high shear. It was found that the floc size during the steady phase of growth was small, while the regrowing capability decreased in the presence of humic acid. The recoverability was closely related with floc breakage modes including floc structural fragmentation and floc surface erosion. The fractal dimensions of alum-kaolin flocs by mass-size method based on microbalance would decrease with increasing humic concentration. This study proved that humic acid had adverse influences on the performance of coagulation process.
基金supported by National Natural Science Foundation of China (Nos. 61773201, 62073165)the 111 Project,China (No. B20007)the Fundamental Research Funds for the Central Universities, China (No. NZ2020003)。
文摘Probabilistic Fault Recoverability(FR) property reveals the capability of a system to accommodate faults under admissible input energy constraints in the sense of satisfactory probability. Motivated by the idea of probabilistic control methods, a class of admissible probability density functions is designed for detailed description of fault parameters, under which several probabilistic FR conditions are established. This significantly enlarges the range of recoverable faults obtained from the deterministic FR analysis. The tradeoffs between the risk of performance degradation and this increased recoverability margin are exactly achieved by allowing a small risk of FR violation. This paper analyzes the probability FR of dynamic systems with switching and interconnection characteristics, and applies the new results to several aircraft models including single longitudinal aircraft dynamic, Highly Maneuverable Technology(HiMAT) vehicle and meta aircraft. Simulation results show the efficiency of the proposed methods based on the comparison between deterministic and probabilistic cases.
基金Supported by the China National Science and Technology Major Project(2016ZX05046)National Key R&D Program(2018YFE0196000)Consulting Research Project of Chinese Academy of Engineering(2019-XZ-61)。
文摘This paper targets the shale oil reservoirs of middle to high maturity in four major basins of China,including the Permian Lucaogou Formation of the Jimsar Sag in the Junggar Basin,the Chang 73 Member of the Triassic Yanchang Formation in the Longdong area of the Ordos Basin,the Kong 2 Member of the Paleogene Kongdian Formation in Cangdong Sag of the Bohai Bay Basin,and the Qing 1 Member of the Cretaceous Qingshankou Formation in Changling Sag of the Songliao Basin.The key parameters of the shale oil reservoirs in the four basins,such as reservoirs effectiveness,oil content,crude oil movability,and fracability,have been revealed under identical experimental conditions using the same evaluation technical system,on the basis of technique development and integrated application of multi-scale spatial distribution depiction,effective connectivity calculation,movable oil assessment based on the charging effect,and simulation of fracture propagation during reservoir stimulation.This research overcomes insufficient resolutions of conventional analysis approaches and difficulties in quantitative evaluation,develops the evaluation method for resource recoverability of different types of shale oil,and gains insights into different types of shale oil via comparison.The results of experiments and comparative analysis show that there are significant differences in the endowment of continental shale oil resources in the four major basins in China.Among them,the Lucaogou Formation in the Junggar Basin has more effective shale reservoirs,the Chang 73 sub-member of the Ordos Basin has a comparatively good proportion of movable oil and the Kong 2 Member of the Bohai Bay Basin has the best fracability.These results can provide references and basis for choosing development plans and engineering techniques.
基金supported by the International Cooperation Project of Guangdong Natural Science Fund(2009B050700020)the Natural Science Foundation of China-Guangdong Natural Science Foundation Union Project(U0835003)
文摘Recoverability of block-sparse signals by convex relaxation methods is considered for the underdetermined linear model. In previous works, some explicit but pessimistic recoverability results which were associated with the dictionary were presented. This paper shows the recoverability of block-sparse signals are associated with the block structure when a random dictionary is given. Several probability inequalities are obtained to show how the recoverability changes along with the block structure parameters, such as the number of nonzero blocks, the block length, the dimension of the measurements and the dimension of the block-sparse representation signal. Also, this paper concludes that if the block-sparse structure can be considered, the recoverability of the signals wil be improved. Numerical examples are given to il ustrate the availability of the presented theoretical results.
文摘Sustainably managing vehicles at their end-of-life stage(ELVs)presents significant potential forresource recovery,effectively addressing resource scarcity through the closure of the material loop.While ELVs in countries like Morocco have traditionally been treated as waste rather than secondaryresource material(SRM),they have the potential to reduce reliance on primary materials when usedjudiciously.Despite policymakers aiming for increased resource efficiency in the automobile sector,there is limited research exploring the role of the informal sector in recovering materials and parts fromELVs.This study investigates the ELV processing scenario at Salmia scrap market,recognized as one of Africa’s largest informal markets for ELVs.Using a mass-balance approach,the disposal of sedan cars isexamined,and a conceptual framework illustrating the process flow and interactions among multiplestakeholders is developed.From sampled sedan cars,approximately 7% of aluminum and 76%of iron,by weight,are recovered.These findings contribute to estimating the potential for recycling andrecovering materials from ELVs processed by the informal sector in Morocco.In a standard operationalcontext,estimations suggest that the sector holds substantial potential to recover aluminum and iron by2030.This underscores the importance of formalizing operations and integrating informal players intothe value chain to effectively address resource scarcity within a circular economy.
基金This study was financially supported by the National Natural Science Foundation of China(Grant No.42072162)the Natural Science Foundation of Shandong Province(No.ZR2020MD036)a forward-looking and basic technology research project of PetroChina(No.2021DJ2301).
文摘Pores are the main accumulation sites and migration pathways for coalbed methane(also referred to as CBM).Pore structure restricts the content and recoverability of CBM from coal reservoirs.In this study,12 representative coal samples with different ash yields that have similar tectonic characteristics and burial depths were collected from different mining areas in the Jiergalangtu and Huolinhe depressions in the Erlian Basin.These samples were used to study the restrictions of ash yield on the characteristics of coal pore structures and the recoverability of CBM through macroscopic and microscopic structure observation,scanning electron microscope observations,vitrinite reflectance tests,low-temperature N2 adsorption,nuclear magnetic resonance(NMR),and micro-computed tomography.The results show that coal reservoirs in the study area vary greatly in ash yield,based on which they can be divided into three types,i.e.,low-ash-content,ash-bearing,and high-ash-content coal reservoirs.In addition,the ash yield has a certain impact on the development of coal pores;coal samples with lower ash yields indicate the presence of well-developed medium-large pores and better connectivity.Ash yield also has a certain impact on the brittleness of coal wherein a lower ash yield implies the development of brittle coal that is more liable to fracture as compared to less brittle samples at the same pressure.Absorbed gas content also varies significantly with ash yield;a low ash yield impacts the gas saturation of coal.Overall,for coal reservoirs in the study area,their porosity,pore diameter,movable fluid porosity,adsorbed gas amount,and recoverability decrease as the ash yield increases.
基金supported by Emerging Industry Leading Talent Project of Shanxi Province(No.2020587).
文摘The nutritional situation of the elderly is closely related to the occurrence and development of many diseases.How to reduce the damage of surgery,and improve the postoperative survival rate and quality of life in malnourished elderly patients is very important.Through the elderly malnutrition perioperative risk factors analysis,we make strategies for risk factors of perioperative-related prevention,from preoperative,intraoperative,and postoperative management of patients,to improve the patient’s life.
基金supported by National Natural Science Foundation of China(No.62172436)Additionally,it is supported by Natural Science Foundation of Shaanxi Province(No.2023-JC-YB-584)Engineering University of PAP’s Funding for Scientific Research Innovation Team and Key Researcher(No.KYGG202011).
文摘Cloud storage,a core component of cloud computing,plays a vital role in the storage and management of data.Electronic Health Records(EHRs),which document users’health information,are typically stored on cloud servers.However,users’sensitive data would then become unregulated.In the event of data loss,cloud storage providers might conceal the fact that data has been compromised to protect their reputation and mitigate losses.Ensuring the integrity of data stored in the cloud remains a pressing issue that urgently needs to be addressed.In this paper,we propose a data auditing scheme for cloud-based EHRs that incorporates recoverability and batch auditing,alongside a thorough security and performance evaluation.Our scheme builds upon the indistinguishability-based privacy-preserving auditing approach proposed by Zhou et al.We identify that this scheme is insecure and vulnerable to forgery attacks on data storage proofs.To address these vulnerabilities,we enhanced the auditing process using masking techniques and designed new algorithms to strengthen security.We also provide formal proof of the security of the signature algorithm and the auditing scheme.Furthermore,our results show that our scheme effectively protects user privacy and is resilient against malicious attacks.Experimental results indicate that our scheme is not only secure and efficient but also supports batch auditing of cloud data.Specifically,when auditing 10,000 users,batch auditing reduces computational overhead by 101 s compared to normal auditing.
文摘In recent years,deep learning has been introduced into the field of Single-pixel imaging(SPI),garnering significant attention.However,conventional networks still exhibit limitations in preserving image details.To address this issue,we integrate Large Kernel Convolution(LKconv)into the U-Net framework,proposing an enhanced network structure named U-LKconv network,which significantly enhances the capability to recover image details even under low sampling conditions.
基金the financial support of the National Natural Science Foundation under Grant No.52274387project support by the Shanghai Science and Technology Com-mission(Grant No.20S31900100).
文摘Bone-mimicking gradient porous NiTi shape memory alloys(SMAs)are promising for orthopedic im-plants due to their distinctive superelastic functional properties.However,premature plastic deformation in weak areas such as thinner struts,nodes,and sharp corners severely deteriorates the superelasticity of gradient porous NiTi SMAs.In this work,we prepared gradient porous NiTi SMAs with a porosity of 50%by additive manufacturing(AM)and achieved a remarkable improvement of superelasticity by a simple solution treatment regime.After solution treatment,phase transformation temperatures dropped signif-icantly,the dislocation density decreased,and partial intergranular Ti-rich precipitates were transferred into the grain.Compared to as-built samples,the strain recovery rate of solution-treated samples was nearly doubled at a pre-strain of 6%(up to 90%),and all obtained a stable recoverable strain of more than 4%.The remarkable superelasticity improvement was attributed to lower phase transformation tem-peratures,fewer dislocations,and the synergistic strengthening effect of intragranular multi-scale Ti-Ni precipitates.Notably,the gradient porous structure played a non-negligible role in both superelasticity deterioration and improvement.The microstructure evolution of the solution-treated central strut after constant 10 cycles and the origin of the stable superelastic response of gradient porous NiTi SMAs were revealed.This work provides an accessible strategy for improving the superelastic performance of gra-dient porous NiTi SMAs and proposes a key strategy for achieving such high-performance architectured materials.
基金supported by the National Natural Science Foundation of China(Nos.12132002,12202044)。
文摘In the process of stage separation of recoverable liquid launch vehicles,because of the large amount of residual fuel in the storage tanks,the influence of liquid sloshing on separation safety must be considered.Considering calculation simplicity and operation practicability,the Moving Pulsating Ball Model(MPBM)of large amplitude liquid sloshing is introduced into the calculation of launch vehicle stage separation.Combining the dynamic equation of the model with the energy relationship during"breathing movement",the formula calculating the force of liquid on the rigid body is derived.Compared with the calculations of commercial CFD calculation software,the accuracy of MPBM model is verified.Then,all the external forces and moments are applied to the rigid body of the stages,so that the translational and rotational dynamic equations of the stages are obtained respectively.According to the relative position of the two stages,the geometric shape of the interstage section and the engine of the second stage,the minimum clearance in the separation process can be decided to guarantee that the separation process is safe.
基金Financial support from Key Research and Development Projects of Shaanxi Province(2024GX-YBXM-508)Research Fund for Young Star of Science and Technology in Shaanxi Province(2023KJXX-124)are gratefully acknowledged.
文摘The circulating water system is widely used as the cooling system in the process industry,which has the characteristics of high water and power consumption,and its energy consumption level has an important impact on the economic performance of the whole system.Pump network and water turbine network constitute the work network of the circulating water system,that is,the fluid machinery network.Based on the previous studies,this paper proposes a stepwise method to optimize the fluid machinery network,that is,to optimize the network structure by using the recoverable pressure-head curve of the branch,and consider the recovery of adjustable resistance at the valve of each branch,so as to further reduce energy consumption and water consumption.The calculation result of the case shows that the topology structure optimization can further reduce the operation cost and the annual capital cost on the basis of the fixed structure optimization,and the total annualized cost can be reduced by 30.04%.The optimization result of different flow shows that both the pump network and the water turbine network tend to series structure at a low flow rate whereas to parallel structure at a high flow rate.
文摘The long-term exposure of building structures in coastal areas of our country to corrosive environment will lead to a significant decrease in the seismic performance of structures due to the corrosion of steel bars in reinforced concrete structures. Starting from the concept of seismic recoverability of building structures, this paper introduces the evaluation method of seismic recoverability of corroded reinforced concrete structures based on functional deterioration, and summarizes the relevant numerical simulation research of corroded reinforced concrete frame structures under the standard design in our country. The results show that steel corrosion in reinforced concrete structures under corrosive environment has a significant impact on the seismic recoverability of the structures. With the increase of steel corrosion degree, the seismic recoverability of the target structures will be significantly reduced. The research results can provide theoretical support and reference for seismic recoverability evaluation of similar structures.
基金National Natural Science Foundation of China,No.41801122GDAS’ Special Project of Science and Technology Development,No.2016GDASRC-0101,No.2018GDASCX-0901
文摘In the aftermath of the global financial crisis of 2008,China witnessed gradual shrinkage of cities in the Pearl River Delta(PRD).In this study,we introduce the concept of economic resilience to analyse urban growth and shrinkage in the context of a rapidly-urbanising region.Multiple regression analysis is performed to explore the determinants of economic resilience in the PRD.By measuring resistance in the shrinking phase and recoverability in the growing phase in a group of cities in the PRD,this study distinguishes four scenarios and investigates their characteristics from a spatial perspective.The results demonstrate that the financial crisis had a severe and asymmetric influence on this area,indicating more than 15%of cities are faced with shrinking.The spatial distribution of economic resilience indicates a centre-periphery pattern,that is,high economic resilience in the inner ring and low economic resilience in the outer ring of the PRD.The service economy is found to play a significant role in promoting urban economic resilience.Results imply that sound economic policies for enhancing resilience:both poor local financial status and a high degree of export concentration adversely impact resistance,while upgrading the manufacturing economy and stimulating of industrial innovation are conducive to improve recoverability.
文摘An asymmetry power clock,4 phase power clock supplying the power to the DSCRL(dual swing charge recovery logic) adiabatic circuit is presented.It is much simpler than the 6 phase power clock,symmetry power clock,used in the DSCRL adiabatic circuit.Although the 4 phase power clock is simpler,the DSCRL adiabatic circuit still shows good performance and high efficiency of energy transfer and recovery.This conclusion has been proved by the result of the HSPICE simulation using the 0 6μm CMOS technology.
文摘The study aims at exploring the possibility of using the recovery ability af- ter drought stress-rewatering at vegetative growth stage as the evaluating index in water use efficiency （WUE） of winter wheat varieties. ＇Jing 411 ＇, ＇Jinmai 47＇ and their 34 near isogenic lines （NILs） were used as test materials. Semi-automatic rainproof shelter and the percolating pools were used for simulating drought treat- ment. After suffering severe drought stress, winter wheat crops were rewatered at early jointing stage. The biomass accumulation after rewatering was determined as recovery ability index. In the meanwhile, plant height in the end of vegetative growth stage was measured, and WUE of varieties/lines was also determined. Thereafter, the differences in recovery ability, plant height and the population WUE, together with the correlation between recovery ability and population WUE were analyzed, respectively. The results showed that there were significant differences in recovery ability among some varieties/lines. The recovery ability was affected by both geno- type and environment, and the interaction existed in these two factors. Significant differences existed in plant height and population WUE among the 34 NILs along with their parents. There was a significantly positive correlation between recovery ability and plant height of varieties/lines. Recovery ability and plant height were very significantly and positively correlated with population yield WUE respectively. The re- sults indicated that recovery ability after drought stress-rewatering could be used as an evaluating index of population WUE under drought condition.
基金Project supported by National Major Science and Technology Project“High efficiency development demonstration project of high-rank CBM in the Qinshui Basin”(No.:2017ZX05064)PetroChina Major Science and Technology Project“Study on the production-increase technology of highrank CBM development”(No.:2017E-1404).
文摘After over 10 years'development of coalbed methane(CBM)industry in China,two industrial bases have been built,i.e.,the Qinshui Basin and the Ordos Basin.However,the biggest problem that restricts the high-efficiency development of CBM industry in China is that average single-well gas production rate is low.At present,the production of high-rank CBM accounts for more than 90%of total CBM production in China.In the future,the exploitation field of high-rank CBM resources will focus on the deep and medium reservoirs.The complex CBM occurrence and flow conditions(e.g.different tectonic field,stress field and fracture field)bring great challenges to the adaptability of existing engineering technologies to geological conditions.In this regard,this paper takes the research and practice of high-rank CBM technologies in the Qinshui Basin of PetroChina Huabei Oilfield Company as an example to analyze the“four low”(low effective reserve producing ratio,low remaining producible reserves,low single-well gas production rate and low exploitation profit)CBM exploitation phenomena and discuss the essence of CBM exploitation dialectically.And the following research results were obtained.First,current major problems in CBM exploitation include CBM reserve recoverability,geological difference,engineering technological adaptability and scientific drainage gas recovery.Second,the only way for scientific CBM exploitation is to break through the key bottlenecks under existing technical conditions,including control technology for reserve development,regional selection technology for economic productivity construction,engineering technology suitable for geological characteristics and top-level design technology for scheme preparation.Third,the exploitation practice achievements of high-rank CBM in the Mabidong Block and medium-rank CBM in the Dacheng uplift are realized by breaking the traditional geological cognitions and breaking through the restricted idea that the CBM below 800 m is not suitable to be developed.And it is demonstrated that burial depth is not the limitation condition to determine if CBM can be exploited and medium and deep reservoirs are not the forbidden areas of CBM exploitation.
基金Scientific and Technological Project of China National Petroleum Exploration and Production Corporation"Research on North China Coalbed Methane Reserve Utilization and Beneficial Development Technology"(kt2021-10-07)China National Petroleum North China Technology Project of Oilfield Company"Geological Design Technology of High Coalbed Methane Horizontal Well and Implementation Tracking Research"(2022-HB-M03).
文摘There are abundant high-rank coal bed methane(CBM)resources in China,accounting for one third of total CBM resources.Its efficient development and utilization is of great significance to guarantee the national energy strategic security,diminish the hidden danger of coal mine production and reduce carbon dioxide emission.In order to solve the"four lows"problem(i.e.,low effective utilization ratio of proved reserves,low productivity targeting ratio,low single-well production rate and low development profit)restricting the development of high-rank CBM industry in China,this paper deeply analyzes the core problems restricting the development of high-rank CBM.Based on this,several new methods of production control,area selection and evaluation are put forward by taking multiple measures,such as paying the same attention on theoretical research and technological research&development,carrying out laboratory research and field test in parallel and conducting large scale construction and benefit development simultaneously.And the following research results are obtained.First,the geological difference between CBM and coal mine,the difference in reserves recoverability,the adaptability of engineering technology and the scientificity of production are the main factors restricting CBM development effect.Second,"Four-element"production control theory,methane-leading en gineering transformation method and methane-leading production control theory are proposed,which provides guidance for the development of a series of technologies for the efficient development of high-rank CBM.Third,in practice,the control degree of quality reserves is increased from 32%to 80%,the success ratio of development wells is increased from 60%to 95%,the average single-well daily gas production of vertical wells is increased by about 1100 m^(3),the drilling cost of horizontal wells is reduced by 50%,and the operation cost per cubic meter of gas is reduced by 24%.In conclusion,the established technology series for the efficient development of high-rank CBM actively promote the efficient CBMdevelopment in the Qinshui Basin.The yearly CBM production of PetroChina Huabei Oilfield Company is expected to reach 20108 m^(3) in the middle of the"14th Five-Year Plan",which promotes the strategic development of CBM industry in China.
基金Supported by National Key R&D Program of China(Grant No.2022YFE0138500)National Natural Science Foundation of China(Grant No.51975246)+2 种基金Science and Technology Development Program of Jilin Province of China(Grant No.20220101192JC)Capital Construction Fund Plan within the Budget of Jilin Province of China(Grant No.2023C041-4)Chongqing Municipal Natural Science Foundation of China(Grant No.CSTB2022NSCQ-MSX0225).
文摘With the deepening of human research on deep space exploration,our research on the soft landing methods of landers has gradually deepened.Adding a buffer and energy-absorbing structure to the leg structure of the lander has become an effective design solution.Based on the energy-absorbing structure of the leg of the interstellar lander,this paper studies the appearance characteristics of the predatory feet of the Odontodactylus scyllarus.The predatory feet of the Odontodactylus scyllarus can not only hit the prey highly when preying,but also can easily withstand the huge counter-impact force.The predatory feet structure of the Odontodactylus scyllarus,like a symmetrical cone,shows excellent rigidity and energy absorption capacity.Inspired by this discovery,we used SLM technology to design and manufacture two nickel-titanium samples,which respectively show high elasticity,shape memory,and get better energy absorption capacity.This research provides an effective way to design and manufacture high-mechanical energy-absorbing buffer structures using bionic 3D printing technology and nickel-titanium alloys.
