The pressure-preserving controller is the core part of deep in-situ pressure-preserving coring(IPP-Coring) system, and its pressure-preserving capability is the key to IPP-Coring technology. To achieve a good understa...The pressure-preserving controller is the core part of deep in-situ pressure-preserving coring(IPP-Coring) system, and its pressure-preserving capability is the key to IPP-Coring technology. To achieve a good understanding of the influence of mechanical properties of materials on the ultimate pressure-bearing capability(UPB-Capability) of the pressure-preserving controller, the IPP-Coring experimental platform was developed to test the UPB-Capability of pressure-preserving controllers of four different materials. The experimental results show that the UPB-Capability of pressure-preserving controllers with different material varies greatly. A numerical model of the pressure-preserving controller was developed to study the influences of mechanical parameters of materials on the UPB-Capability of the pressurepreserving controller after the accuracy of the numerical model is verified by experiments. The results indicate that the yield strength(YS) and Poisson's ratio(PR) of the material have little effect on the UPB-Capability of the pressure-preserving controller, whereas the elastic modulus(EM) of the material has a significant effect. A generalized model of the UPB-Capability of the pressure-preserving controller is developed to reveal the mechanism of the influence of material properties on the UPB-Capability of the pressure-preserving controllers. Considering these results, the future optimization direction of the pressure-preserving controller and material selection scheme in practical engineering applications of the pressure-preserving controller are suggested.展开更多
We systemically investigate optical trapping capability of a kind of tornado waves on Rayleigh particles.Such tornado waves are named as tornado circular Pearcey beams(TCPBs)and produced by combining two circular Pear...We systemically investigate optical trapping capability of a kind of tornado waves on Rayleigh particles.Such tornado waves are named as tornado circular Pearcey beams(TCPBs)and produced by combining two circular Pearcey beams with different radii.Our theoretical exploration delves into various aspects,including the propagation dynamics,energy flux,orbital angular momentum,trapping force,and torque characteristics of TCPBs.The results reveal that the orbital angular momentum,trapping force,and torque of these beams can be finely tuned through the judicious manipulation of their topological charges(l_(1)and l_(2)).Notably,we observe a precise control mechanism wherein the force diminishes with|l_(1)+l_(2)|and|l_(1)-l_(2)|,while the torque exhibits enhancement by decreasing solely with|l_(1)+l_(2)|or increasing with|l_(1)-l_(2)|.These results not only provide quantitative insights into the optical trapping performance of TCPBs but also serve as a valuable reference for the ongoing development of innovative photonic tools.展开更多
Weakened capability of eating and swallowing is common among elderly population,affecting negatively on their health and well-being.This work measured occlusal force and tongue muscle strength of elderly patients and ...Weakened capability of eating and swallowing is common among elderly population,affecting negatively on their health and well-being.This work measured occlusal force and tongue muscle strength of elderly patients and then assessed whether correlations existed between oral physiological properties and the eating and swallowing capability.A total of 26 elderly patients with potential swallow disorder were recruited in this work.Participants’denture status and daily diet texture were determined by a pre-questionnaire analysis.Their swallowing capability was assessed and rated by water drinking test.Maximum tongue pressure,incisor occlusal force and hand gripping force were measured for each subject.It was observed that participating subjects have on average a significantly lower biting force and maximum tongue pressure than that of normal adults.The swallowing grades assessed by water drinking test showed significant correlations with both the biting force(r=−0.498,P<0.05)and the tongue muscle strength(r=−0.544,P<0.05).The biting force of dysphagia participants correlates significantly with dental conditions(P<0.05).The observed correlation between tongue pressure and diet texture indicates that tongue muscle strength could be used as a reliable indicator of the eating and swallowing capability for elderly people.展开更多
In response to the development of deep-sea oil and gas resources,which require a high degree of cooperation by crude oil transportation equipment,a new type of ship known as the cargo transfer vessel(CTV)has been deve...In response to the development of deep-sea oil and gas resources,which require a high degree of cooperation by crude oil transportation equipment,a new type of ship known as the cargo transfer vessel(CTV)has been developed.To provide a theoretical reference for the design and equipment of the CTV’s dynamic positioning system,in this paper,we take the new deepwater CTVas the study object and theoretically and numerically analyze its operation,wind load,current load,wave load,and navigational resistance in a range of Brazilian sea conditions with respect to its positioning and towing modes.We confirm that our proposed method can successfully calculate the total environmental load of the CTVand that the CTV is able to operate normally under the designed sea conditions.展开更多
"Beauty is truth, truth beauty"-the famous line in English romantic poet John Keats'Ode on a Grecian Urn-has triggered wide discussion and numerous interpretations. From the point of"negative capabi..."Beauty is truth, truth beauty"-the famous line in English romantic poet John Keats'Ode on a Grecian Urn-has triggered wide discussion and numerous interpretations. From the point of"negative capability", a phrase first coined by Keats himself, this paper is attempting to display the consistency between that poetic line and the poet's creation and life attitude on the whole. For this purpose, this paper will mainly introduce and interpret five of Keats'famous odes in the order of their display of his"rising acceptance of life": Ode to a Nightingale, Ode on a Grecian Urn, Ode to Autumn, Ode on Melancholy and Ode on Indolence. This paper would like to show in the first three Keats's positive quest in different aspects and on certain levels, the fourth the underlying tone of life's polyphonous song, and the final the"negative capability"that constitutes his healthy attitude toward creation and life. Finally, this paper hopes to demonstrate that it is such capability that enables the poet to growingly accept life, and it is also essential to him as a philosophical poet.展开更多
In order to balance electrochemical kinetics with loading level for achieving efficient energy storage with high areal capacity and good rate capability simultaneously for wearable electronics,herein,2 D meshlike vert...In order to balance electrochemical kinetics with loading level for achieving efficient energy storage with high areal capacity and good rate capability simultaneously for wearable electronics,herein,2 D meshlike vertical structures(NiCo_2 S_4@Ni(OH)_2) with a high mass loading of 2.17 mg cm^(-2) and combined merits of both 1 D nanowires and 2 D nanosheets are designed for fabricating flexible hybrid supercapacitors.Particularly,the seamlessly interconnected NiCo_2 S_4 core not only provides high capacity of 287.5 μAh cm^(-2) but also functions as conductive skeleton for fast electron transport;Ni(OH)_2 sheath occupying the voids in NiCo_2 S_4 meshes contributes extra capacity of 248.4 μAh cm^(-2);the holey features guarantee rapid ion diffusion along and across NiCO_2 S_4@Ni(OH)_2 meshes.The resultant flexible electrode exhibits a high areal capacity of 535.9 μAh cm^(-2)(246.9 mAh g^(-1)) at 3 mA cm^(-2) and outstanding rate performance with 84.7% retention at 30 mA cm^(-2),suggesting efficient utilization of both NiCo_2 S_4 and Ni(OH)_2 with specific capacities approaching to their theoretical values.The flexible solid-state hybrid device based on NiCo_2 S_4@Ni(OH)_2 cathode and Fe_2 O_3 anode delivers a high energy density of 315 μWh cm^(-2) at the power density of 2.14 mW cm^(-2) with excellent electrochemical cycling stability.展开更多
The two kinds of super absorbent resins from carboxymethyl cellulose were synthesized with the potassium persulphate and methylenebisacrylamide as initiator and cross linker respectively by radical polymerization in a...The two kinds of super absorbent resins from carboxymethyl cellulose were synthesized with the potassium persulphate and methylenebisacrylamide as initiator and cross linker respectively by radical polymerization in aqueous solution. Thestructures of the two resins were characterized with Fourier transform infrared spectroscopy FTIR, scanning electron miscroscopy （SEM）, and environment scanning electron miscroscopy （ESEM）, the results indicate that the fibriform of the carboxymethyl cellulose （CMC） is disappeared and the crusslink networks in eopolymer of carboxymethyl cellulose-graft-polyacrylic acid（CMC-g-PAA） are denser than that of eopolymer of carboxymethyl cellulose-graft-poly （acrylic acid-co-N-vinyl Pyrrolidone） （CMC-g- PAA-co-PVP）. The comparison between the two resins in absorption capacities is that CMC-g-PAA is better in the water-keep capability being heated, while CMC-g-PAA-co-PVP is better in the water absorbency and salt resistance.展开更多
The superposition dynamics of two confronting ultrasonic waves and their levitation capability for centimeter-sized thin disks are investigated by numerical analyses and validated by experiments. The sound pressure si...The superposition dynamics of two confronting ultrasonic waves and their levitation capability for centimeter-sized thin disks are investigated by numerical analyses and validated by experiments. The sound pressure simulation reveals that two opposite ultrasonic waves provide a more effective standing-wave field than a single ultrasonic wave when the diameter of disk-shaped object approaches the wavelength scale. The dynamic superposition of two confronting beams facilitates the acoustic levitation of the clay disk and aluminum disk with diameters of 0.97 and 0.90. The acoustic radiation forces exerting on these thin disks are measured experimentally, which exhibit a better levitation stability for the centimeter-sized thin disks. The equilibrium levitation positions of the two disks are located near the sound pressure node, and the maximum acoustic radiation pressure on their surfaces is less than one percent of the maximum sound pressure.展开更多
The penetration rate of distributed generation is gradually increasing in the distribution system concerned.This is creating new problems and challenges in the planning and operation of the system.The intermittency an...The penetration rate of distributed generation is gradually increasing in the distribution system concerned.This is creating new problems and challenges in the planning and operation of the system.The intermittency and variability of power outputs from numerous distributed renewable generators could significantly jeopardize the secure operation of the distribution system.Therefore,it is necessary to assess the hosting capability for intermittent distributed generation by a distribution system considering operational constraints.This is the subject of this study.An assessment model considering the uncertainty of generation outputs from distributed generators is presented for this purpose.It involves different types of regulation or control functions using on-load tap-changers(OLTCs),reactive power compensation devices,energy storage systems,and the reactive power support of the distributed generators employed.A robust optimization model is then attained It is solved by Bertsimas robust counterpart through GUROBI solver.Finally,the feasibility and efficiency of the proposed method are demonstrated by a modified IEEE 33-bus distribution system.In addition,the effects of the aforementioned regulation or control functions on the enhancement of the hosting capability for intermittent distributed generation are examined.展开更多
Because of the discrete charge storage mechanism, charge trapping memory（CTM） technique is a good candidate for aerospace and military missions. The total ionization dose（TID） effects on CTM cells with Al2O3/HfO2/...Because of the discrete charge storage mechanism, charge trapping memory（CTM） technique is a good candidate for aerospace and military missions. The total ionization dose（TID） effects on CTM cells with Al2O3/HfO2/Al2O3（AHA） high-k gate stack structure under in-situ 10 keV x-rays are studied. The C-V characteristics at different radiation doses demonstrate that charge stored in the device continues to be leaked away during the irradiation,thereby inducing the shift of flat band voltage（V（fb））. The dc memory window shows insignificant changes, suggesting the existence of good P/E ability. Furthermore, the physical mechanisms of TID induced radiation damages in AHA-based CTM are analyzed.展开更多
The effective plugging of artificial fractures is key to the success of temporary plugging and diverting fracturing technology,which is one of the most promising ways to improve the heat recovery efficiency of hot dry...The effective plugging of artificial fractures is key to the success of temporary plugging and diverting fracturing technology,which is one of the most promising ways to improve the heat recovery efficiency of hot dry rock.At present,how temporary plugging agents plug artificial fractures under high temperature remains unclear.In this paper,by establishing an improved experimental system for the evaluation of temporary plugging performance at high temperature,we clarified the effects of high temperature,injection rate,and fracture width on the pressure response and plugging efficiency of the fracture.The results revealed that the temporary plugging process of artificial fractures in hot dry rock can be divided into four main stages:the initial stage of temporary plugging,the bridging stage of the particles,the plugging formation stage,and the high-pressure dense plugging stage.As the temperature increases,the distribution distance of the temporary plugging agent,the number of pressure fluctuations,and the time required for crack plugging increases.Particularly,when the temperature increases by 100℃,the complete plugging time increases by 90.7%.展开更多
A laser-diode pumped passive Q-switched Nd:YAG/Cr^(4+):YAG laser with quick tunable pulse-width capability is studied and experimentally demonstrated. By focusing the auxiliary controlling laser beam onto a Cr^(4+):YA...A laser-diode pumped passive Q-switched Nd:YAG/Cr^(4+):YAG laser with quick tunable pulse-width capability is studied and experimentally demonstrated. By focusing the auxiliary controlling laser beam onto a Cr^(4+):YAG crystal and thereby changing the initial transmission of the Cr^(4+):YAG crystal, laser pulses with different pulse widths can be achieved. The obtained laser pulse width is tunable in the range of 550–1492 ps with a fixed cavity length of 7 mm. The laser can be used to achieve different pulse widths between two pulses in the range of sub-nanosecond to a few tens of nanoseconds.展开更多
Antimony(Sb) is an attractive cathode for liquid metal batteries(LMBs) because of its high theoretical voltage and low cost.The main obstacles associated with the Sb-based cathodes are unsatisfactory energy density an...Antimony(Sb) is an attractive cathode for liquid metal batteries(LMBs) because of its high theoretical voltage and low cost.The main obstacles associated with the Sb-based cathodes are unsatisfactory energy density and poor rate-capability.Herein,we propose a novel Sb_(64)Cu_(36)cathode that effectively tackles these issues.The Sb_(64)Cu_(36)(melting point:525℃) cathode presents a novel lithiation mechanism involving sequentially the generation of Li_(2)CuSb,the formation of Li_(3)Sb,and the conversion reaction of Li_(2)CuSb to Li_(3)Sb and Cu.The generated intermetallic compounds show a unique microstructure of the upper floated Li_(2)CuSb layer and the below cross-linked structure with interpenetrated Li_(2)CuSb and Li_(3)Sb phases.Compared with Li_(3)Sb,the lower Li migration energy barrier(0.188 eV) of Li_(2)CuSb significantly facilitates the lithium diffusion across the intermediate compounds and accelerates the reaction kinetics.Consequently,the Li‖Sb_(64)Cu_(36)cell delivers a more excellent electrochemical performance(energy density:353 W h kg^(-1)at 0.4 A cm^(-2);rate capability:0.59 V at 2.0 A cm^(-2)),and a much lower energy storage cost of only 38.45 $ kW h^(-1)than other previously reported Sb-based LMBs.This work provides a novel cathode design concept for the development of high-performance LMBs in applications for large-scale energy storage.展开更多
Aiming at the deficiency of exterminating measures of Chinese firm safety management, a simulation model of Chinese firm＇s safety management capability based on the organizational learning theory, in which the simula...Aiming at the deficiency of exterminating measures of Chinese firm safety management, a simulation model of Chinese firm＇s safety management capability based on the organizational learning theory, in which the simulation method of system dynamics is utilized. The level variable and rate variable are designed based on the practical situation and change situation of corresponding variables of firm＇s safety management ca- pability. Simulation firms are built with accident case groups of the oil industry, chemical industry, machine industry, coal mining industry, and weapon industry. Through analyzing the simulation result, the growth law of Chinese firm＇s safety management capability is obtained as follows： the accumulating and the coupling of safety knowledge should be emphasized at the same time; the balance of learning behavior of individual, group and organization should be considered together; different types of Chinese firm should take different safety policies according to their practical situations.展开更多
Ultra-stable piezoelectric nanogenerator(PENG)driven by environmental actuation sources with all-weather service capability is highly desirable.Here,the PENG based on N doped 4H-SiC nanohole arrays(NHAs)is proposed to...Ultra-stable piezoelectric nanogenerator(PENG)driven by environmental actuation sources with all-weather service capability is highly desirable.Here,the PENG based on N doped 4H-SiC nanohole arrays(NHAs)is proposed to harvest ambient energy under low/high temperature and relative humidity(RH)conditions.Finite element method simulation of N doped 4H-SiC NHAs in compression mode is developed to evaluate the relationship between nanohole diameter and piezoelectric performance.The density of short circuit current of the assembled PENG reaches 313 nA cm^(-2),which is 1.57 times the output of PENG based on N doped 4H-SiC nanowire arrays.The enhancement can be attributed to the existence of nanohole sidewalls in NHAs.All-weather service capability of the PENG is verified after being treated at-80/80℃and 0%/100%RH for 50 days.The PENG is promising to be widely used in practice worldwide to harvest biomechanical energy and mechanical energy.展开更多
At present,the world Hi-tech hasbecoming the locomotive of the econom-ic development.In Hi-tech,computerinformation technology has taken up afore running position.Meanwhile,com-puters technology goes deep into manyare...At present,the world Hi-tech hasbecoming the locomotive of the econom-ic development.In Hi-tech,computerinformation technology has taken up afore running position.Meanwhile,com-puters technology goes deep into manyareas such as economy,finance,trade,business,culture life and family life. Thus,the popularity of computer ap-plications technology becomes charac-terizing the important feature of thesocial development.And mastering com-puter technology also becomes a nece-ssary basis of individual,work and life.展开更多
To look through innovation management in small project-based firms, such as software engineering companies, which are service firms that conduct projects for their clients, capability maturity model integration （CMMI...To look through innovation management in small project-based firms, such as software engineering companies, which are service firms that conduct projects for their clients, capability maturity model integration （CMMI） is introduced. It is a process improvement approach that provides organizations with the essential elements of effective processes. Taking ABC Software Company as an example, the performances before and after the introduction of CMMI in the firm were compared. The results indicated that after two years of application, the productivity increased 92%, and the ability of detecting errors improved 26.45% ; while the rate of faults and the cost of software development dropped 12.45% and 77.55%, respectively. To conclude, small project-based firms benefit a lot if they take CMMI into their process of innovation management, particularly for those R＆D firms, since the implementation of CMMI leads them to a promising future with higher efficiency and better effects.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 52225403, 52304146, 51827901)Sichuan Science and Technology Program (2023NSFSC0919)。
文摘The pressure-preserving controller is the core part of deep in-situ pressure-preserving coring(IPP-Coring) system, and its pressure-preserving capability is the key to IPP-Coring technology. To achieve a good understanding of the influence of mechanical properties of materials on the ultimate pressure-bearing capability(UPB-Capability) of the pressure-preserving controller, the IPP-Coring experimental platform was developed to test the UPB-Capability of pressure-preserving controllers of four different materials. The experimental results show that the UPB-Capability of pressure-preserving controllers with different material varies greatly. A numerical model of the pressure-preserving controller was developed to study the influences of mechanical parameters of materials on the UPB-Capability of the pressurepreserving controller after the accuracy of the numerical model is verified by experiments. The results indicate that the yield strength(YS) and Poisson's ratio(PR) of the material have little effect on the UPB-Capability of the pressure-preserving controller, whereas the elastic modulus(EM) of the material has a significant effect. A generalized model of the UPB-Capability of the pressure-preserving controller is developed to reveal the mechanism of the influence of material properties on the UPB-Capability of the pressure-preserving controllers. Considering these results, the future optimization direction of the pressure-preserving controller and material selection scheme in practical engineering applications of the pressure-preserving controller are suggested.
基金Project supported by the National Natural Science Foundation of China(Grant No.11604058)the Guangxi Natural Science Foundation(Grant Nos.2020GXNSFAA297041 and 2023JJA110112)the Innovation Project of Guangxi Graduate Education(Grant No.YCSW2023083)。
文摘We systemically investigate optical trapping capability of a kind of tornado waves on Rayleigh particles.Such tornado waves are named as tornado circular Pearcey beams(TCPBs)and produced by combining two circular Pearcey beams with different radii.Our theoretical exploration delves into various aspects,including the propagation dynamics,energy flux,orbital angular momentum,trapping force,and torque characteristics of TCPBs.The results reveal that the orbital angular momentum,trapping force,and torque of these beams can be finely tuned through the judicious manipulation of their topological charges(l_(1)and l_(2)).Notably,we observe a precise control mechanism wherein the force diminishes with|l_(1)+l_(2)|and|l_(1)-l_(2)|,while the torque exhibits enhancement by decreasing solely with|l_(1)+l_(2)|or increasing with|l_(1)-l_(2)|.These results not only provide quantitative insights into the optical trapping performance of TCPBs but also serve as a valuable reference for the ongoing development of innovative photonic tools.
基金Authors acknowledge a grant support from Chinese Nutrition Society for this project(2015 Chinese Nutrition Society(CNS)Nutrition Research Foundation—DSM Research Fund,grant number:cws201506913).
文摘Weakened capability of eating and swallowing is common among elderly population,affecting negatively on their health and well-being.This work measured occlusal force and tongue muscle strength of elderly patients and then assessed whether correlations existed between oral physiological properties and the eating and swallowing capability.A total of 26 elderly patients with potential swallow disorder were recruited in this work.Participants’denture status and daily diet texture were determined by a pre-questionnaire analysis.Their swallowing capability was assessed and rated by water drinking test.Maximum tongue pressure,incisor occlusal force and hand gripping force were measured for each subject.It was observed that participating subjects have on average a significantly lower biting force and maximum tongue pressure than that of normal adults.The swallowing grades assessed by water drinking test showed significant correlations with both the biting force(r=−0.498,P<0.05)and the tongue muscle strength(r=−0.544,P<0.05).The biting force of dysphagia participants correlates significantly with dental conditions(P<0.05).The observed correlation between tongue pressure and diet texture indicates that tongue muscle strength could be used as a reliable indicator of the eating and swallowing capability for elderly people.
基金This work was finically supported by the National Natural Science Foundation of China(Nos.30800767 and 31271979)the Opening Foundation of Large-scale Equipment in Tianjin University.
基金supported by the National Natural Science Foundation of China(Grant No.51509046)Foundation of Ministry of Industry and Information Technology High-tech Ship Scientific Research(Grant No.2016-26)
文摘In response to the development of deep-sea oil and gas resources,which require a high degree of cooperation by crude oil transportation equipment,a new type of ship known as the cargo transfer vessel(CTV)has been developed.To provide a theoretical reference for the design and equipment of the CTV’s dynamic positioning system,in this paper,we take the new deepwater CTVas the study object and theoretically and numerically analyze its operation,wind load,current load,wave load,and navigational resistance in a range of Brazilian sea conditions with respect to its positioning and towing modes.We confirm that our proposed method can successfully calculate the total environmental load of the CTVand that the CTV is able to operate normally under the designed sea conditions.
文摘"Beauty is truth, truth beauty"-the famous line in English romantic poet John Keats'Ode on a Grecian Urn-has triggered wide discussion and numerous interpretations. From the point of"negative capability", a phrase first coined by Keats himself, this paper is attempting to display the consistency between that poetic line and the poet's creation and life attitude on the whole. For this purpose, this paper will mainly introduce and interpret five of Keats'famous odes in the order of their display of his"rising acceptance of life": Ode to a Nightingale, Ode on a Grecian Urn, Ode to Autumn, Ode on Melancholy and Ode on Indolence. This paper would like to show in the first three Keats's positive quest in different aspects and on certain levels, the fourth the underlying tone of life's polyphonous song, and the final the"negative capability"that constitutes his healthy attitude toward creation and life. Finally, this paper hopes to demonstrate that it is such capability that enables the poet to growingly accept life, and it is also essential to him as a philosophical poet.
基金supported by the National Natural Science Foundation of China (Nos. 21975123, 61704076)the Natural Science Basic Research Program of Shaanxi (No. 2020JM-092)+2 种基金the Natural Science Foundation of Jiangsu Province (No. BK20171018)the Six Talent Peaks Project in Jiangsu Province (No. XCL-024)the Fundamental Research Funds for the Central Universities。
文摘In order to balance electrochemical kinetics with loading level for achieving efficient energy storage with high areal capacity and good rate capability simultaneously for wearable electronics,herein,2 D meshlike vertical structures(NiCo_2 S_4@Ni(OH)_2) with a high mass loading of 2.17 mg cm^(-2) and combined merits of both 1 D nanowires and 2 D nanosheets are designed for fabricating flexible hybrid supercapacitors.Particularly,the seamlessly interconnected NiCo_2 S_4 core not only provides high capacity of 287.5 μAh cm^(-2) but also functions as conductive skeleton for fast electron transport;Ni(OH)_2 sheath occupying the voids in NiCo_2 S_4 meshes contributes extra capacity of 248.4 μAh cm^(-2);the holey features guarantee rapid ion diffusion along and across NiCO_2 S_4@Ni(OH)_2 meshes.The resultant flexible electrode exhibits a high areal capacity of 535.9 μAh cm^(-2)(246.9 mAh g^(-1)) at 3 mA cm^(-2) and outstanding rate performance with 84.7% retention at 30 mA cm^(-2),suggesting efficient utilization of both NiCo_2 S_4 and Ni(OH)_2 with specific capacities approaching to their theoretical values.The flexible solid-state hybrid device based on NiCo_2 S_4@Ni(OH)_2 cathode and Fe_2 O_3 anode delivers a high energy density of 315 μWh cm^(-2) at the power density of 2.14 mW cm^(-2) with excellent electrochemical cycling stability.
基金Basic Research Foundation of Beijing Institute of Technology (BIT-UBF-200504E4202)
文摘The two kinds of super absorbent resins from carboxymethyl cellulose were synthesized with the potassium persulphate and methylenebisacrylamide as initiator and cross linker respectively by radical polymerization in aqueous solution. Thestructures of the two resins were characterized with Fourier transform infrared spectroscopy FTIR, scanning electron miscroscopy （SEM）, and environment scanning electron miscroscopy （ESEM）, the results indicate that the fibriform of the carboxymethyl cellulose （CMC） is disappeared and the crusslink networks in eopolymer of carboxymethyl cellulose-graft-polyacrylic acid（CMC-g-PAA） are denser than that of eopolymer of carboxymethyl cellulose-graft-poly （acrylic acid-co-N-vinyl Pyrrolidone） （CMC-g- PAA-co-PVP）. The comparison between the two resins in absorption capacities is that CMC-g-PAA is better in the water-keep capability being heated, while CMC-g-PAA-co-PVP is better in the water absorbency and salt resistance.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51871186 and 51771156
文摘The superposition dynamics of two confronting ultrasonic waves and their levitation capability for centimeter-sized thin disks are investigated by numerical analyses and validated by experiments. The sound pressure simulation reveals that two opposite ultrasonic waves provide a more effective standing-wave field than a single ultrasonic wave when the diameter of disk-shaped object approaches the wavelength scale. The dynamic superposition of two confronting beams facilitates the acoustic levitation of the clay disk and aluminum disk with diameters of 0.97 and 0.90. The acoustic radiation forces exerting on these thin disks are measured experimentally, which exhibit a better levitation stability for the centimeter-sized thin disks. The equilibrium levitation positions of the two disks are located near the sound pressure node, and the maximum acoustic radiation pressure on their surfaces is less than one percent of the maximum sound pressure.
基金the Scientific and Technological Project of SGCC Headquarters entitled“Smart Distribution Network and Ubiquitous Power Internet of Things Integrated Development Collaborative Planning Technology Research”(5400-201956447A-0-0-00).
文摘The penetration rate of distributed generation is gradually increasing in the distribution system concerned.This is creating new problems and challenges in the planning and operation of the system.The intermittency and variability of power outputs from numerous distributed renewable generators could significantly jeopardize the secure operation of the distribution system.Therefore,it is necessary to assess the hosting capability for intermittent distributed generation by a distribution system considering operational constraints.This is the subject of this study.An assessment model considering the uncertainty of generation outputs from distributed generators is presented for this purpose.It involves different types of regulation or control functions using on-load tap-changers(OLTCs),reactive power compensation devices,energy storage systems,and the reactive power support of the distributed generators employed.A robust optimization model is then attained It is solved by Bertsimas robust counterpart through GUROBI solver.Finally,the feasibility and efficiency of the proposed method are demonstrated by a modified IEEE 33-bus distribution system.In addition,the effects of the aforementioned regulation or control functions on the enhancement of the hosting capability for intermittent distributed generation are examined.
基金Supported by the National Natural Science Foundation of China under Grant No 616340084the Youth Innovation Promotion Association of Chinese Academy of Sciences under Grant No 2014101+1 种基金the International Cooperation Project of Chinese Academy of Sciencesthe Austrian-Chinese Cooperative R&D Projects under Grant No 172511KYSB20150006
文摘Because of the discrete charge storage mechanism, charge trapping memory（CTM） technique is a good candidate for aerospace and military missions. The total ionization dose（TID） effects on CTM cells with Al2O3/HfO2/Al2O3（AHA） high-k gate stack structure under in-situ 10 keV x-rays are studied. The C-V characteristics at different radiation doses demonstrate that charge stored in the device continues to be leaked away during the irradiation,thereby inducing the shift of flat band voltage（V（fb））. The dc memory window shows insignificant changes, suggesting the existence of good P/E ability. Furthermore, the physical mechanisms of TID induced radiation damages in AHA-based CTM are analyzed.
基金supported financially by the Beijing Natural Science Foundation Project(No.3222030)the National Natural Science Foundation of China(No.51936001,No.52274002 and No.52192622)+1 种基金the PetroChina Science and Technology Innovation Foundation Project(2021DQ02–0201)Award Cultivation Foundation from Beijing Institute of Petrochemical Technology(No.BIPTACF-002).
文摘The effective plugging of artificial fractures is key to the success of temporary plugging and diverting fracturing technology,which is one of the most promising ways to improve the heat recovery efficiency of hot dry rock.At present,how temporary plugging agents plug artificial fractures under high temperature remains unclear.In this paper,by establishing an improved experimental system for the evaluation of temporary plugging performance at high temperature,we clarified the effects of high temperature,injection rate,and fracture width on the pressure response and plugging efficiency of the fracture.The results revealed that the temporary plugging process of artificial fractures in hot dry rock can be divided into four main stages:the initial stage of temporary plugging,the bridging stage of the particles,the plugging formation stage,and the high-pressure dense plugging stage.As the temperature increases,the distribution distance of the temporary plugging agent,the number of pressure fluctuations,and the time required for crack plugging increases.Particularly,when the temperature increases by 100℃,the complete plugging time increases by 90.7%.
文摘A laser-diode pumped passive Q-switched Nd:YAG/Cr^(4+):YAG laser with quick tunable pulse-width capability is studied and experimentally demonstrated. By focusing the auxiliary controlling laser beam onto a Cr^(4+):YAG crystal and thereby changing the initial transmission of the Cr^(4+):YAG crystal, laser pulses with different pulse widths can be achieved. The obtained laser pulse width is tunable in the range of 550–1492 ps with a fixed cavity length of 7 mm. The laser can be used to achieve different pulse widths between two pulses in the range of sub-nanosecond to a few tens of nanoseconds.
基金financially supported by the National Natural Science Foundation of China(52074023)the Beijing Natural Science Foundation(2222062)+1 种基金the National Key R&D Program of China(2018YFB0905600)the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(FRF-IDRY-21-023)。
文摘Antimony(Sb) is an attractive cathode for liquid metal batteries(LMBs) because of its high theoretical voltage and low cost.The main obstacles associated with the Sb-based cathodes are unsatisfactory energy density and poor rate-capability.Herein,we propose a novel Sb_(64)Cu_(36)cathode that effectively tackles these issues.The Sb_(64)Cu_(36)(melting point:525℃) cathode presents a novel lithiation mechanism involving sequentially the generation of Li_(2)CuSb,the formation of Li_(3)Sb,and the conversion reaction of Li_(2)CuSb to Li_(3)Sb and Cu.The generated intermetallic compounds show a unique microstructure of the upper floated Li_(2)CuSb layer and the below cross-linked structure with interpenetrated Li_(2)CuSb and Li_(3)Sb phases.Compared with Li_(3)Sb,the lower Li migration energy barrier(0.188 eV) of Li_(2)CuSb significantly facilitates the lithium diffusion across the intermediate compounds and accelerates the reaction kinetics.Consequently,the Li‖Sb_(64)Cu_(36)cell delivers a more excellent electrochemical performance(energy density:353 W h kg^(-1)at 0.4 A cm^(-2);rate capability:0.59 V at 2.0 A cm^(-2)),and a much lower energy storage cost of only 38.45 $ kW h^(-1)than other previously reported Sb-based LMBs.This work provides a novel cathode design concept for the development of high-performance LMBs in applications for large-scale energy storage.
基金the National Social Science Foundation of China (07BJY080)
文摘Aiming at the deficiency of exterminating measures of Chinese firm safety management, a simulation model of Chinese firm＇s safety management capability based on the organizational learning theory, in which the simulation method of system dynamics is utilized. The level variable and rate variable are designed based on the practical situation and change situation of corresponding variables of firm＇s safety management ca- pability. Simulation firms are built with accident case groups of the oil industry, chemical industry, machine industry, coal mining industry, and weapon industry. Through analyzing the simulation result, the growth law of Chinese firm＇s safety management capability is obtained as follows： the accumulating and the coupling of safety knowledge should be emphasized at the same time; the balance of learning behavior of individual, group and organization should be considered together; different types of Chinese firm should take different safety policies according to their practical situations.
基金This work was supported by the National Science Fund for Distinguished Young Scholars(No.52025041)the National Natural Science Foundation of China(No.51974021,51902020,51904021)+2 种基金the Fundamental Research Funds for the Central Universities of NO.FRF-TP-18-045A1 and FRF-TP-19-004B2Zthe National Postdoctoral Program for Innovative Talents(BX20180034)This project is supported by open foundation of Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials,Guangxi University(Grant No.2021GXYSOF12).
文摘Ultra-stable piezoelectric nanogenerator(PENG)driven by environmental actuation sources with all-weather service capability is highly desirable.Here,the PENG based on N doped 4H-SiC nanohole arrays(NHAs)is proposed to harvest ambient energy under low/high temperature and relative humidity(RH)conditions.Finite element method simulation of N doped 4H-SiC NHAs in compression mode is developed to evaluate the relationship between nanohole diameter and piezoelectric performance.The density of short circuit current of the assembled PENG reaches 313 nA cm^(-2),which is 1.57 times the output of PENG based on N doped 4H-SiC nanowire arrays.The enhancement can be attributed to the existence of nanohole sidewalls in NHAs.All-weather service capability of the PENG is verified after being treated at-80/80℃and 0%/100%RH for 50 days.The PENG is promising to be widely used in practice worldwide to harvest biomechanical energy and mechanical energy.
文摘At present,the world Hi-tech hasbecoming the locomotive of the econom-ic development.In Hi-tech,computerinformation technology has taken up afore running position.Meanwhile,com-puters technology goes deep into manyareas such as economy,finance,trade,business,culture life and family life. Thus,the popularity of computer ap-plications technology becomes charac-terizing the important feature of thesocial development.And mastering com-puter technology also becomes a nece-ssary basis of individual,work and life.
文摘To look through innovation management in small project-based firms, such as software engineering companies, which are service firms that conduct projects for their clients, capability maturity model integration （CMMI） is introduced. It is a process improvement approach that provides organizations with the essential elements of effective processes. Taking ABC Software Company as an example, the performances before and after the introduction of CMMI in the firm were compared. The results indicated that after two years of application, the productivity increased 92%, and the ability of detecting errors improved 26.45% ; while the rate of faults and the cost of software development dropped 12.45% and 77.55%, respectively. To conclude, small project-based firms benefit a lot if they take CMMI into their process of innovation management, particularly for those R＆D firms, since the implementation of CMMI leads them to a promising future with higher efficiency and better effects.
