Water mist technology provides efficient firefighting performance while there is still room for improvement. So varieties of additives have been studied in recent years both at home and abroad. The self-made additives...Water mist technology provides efficient firefighting performance while there is still room for improvement. So varieties of additives have been studied in recent years both at home and abroad. The self-made additives are used to compare the firefighting performance of diesel and heptane fire in open space. By adjusting the concentration of substance in the additives and conducting the experiment under the pressure of 0.3 MPa,0.5 MPa and 0.7 MPa,extinguish time and temperature are measured in the experiment. Through the experiments using different fuels,it can be found when the fuel is heptane that has a lower ignition point and a higher evaporation rate, the water mist additive can still significantly improve the firefighting performance. According to the data based on different concentrations of fluorinated surfactants,we find that fluorinated surfactants are the main substance to improve the performances by changing physical property of water mist. Optimal proportion of the additives for firefighting performance is found by experiment results.展开更多
To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments w...To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments were performed on silty clay with water content (mass fraction) of 23.5% and 28.0%, through developed frost-heave test apparatus, in closed or open system. Two sorts of freezing temperature models, namely, constant and sine models, were applied to artificial freezing. The experimental results indicate that the frost-heave degree in seasonal freezing stage accounts for over 90% of the total in open system and it is up to 95% in closed system; the change of artificial sine-freezing temperature has no influence on the frost-heave degree in closed system, however, slight influence in open system. It is found that the variation of temperature gradient of sine-freezing specimen lags behind that of sine-freezing temperature with half phase; sine-freezing temperature model can reduce frost-heave degree of soil. Brand new technology is proposed for the application of artificial ground freezing and new study field of artificial freezing is created.展开更多
Nanosystems play an important role in many applications.Due to their complexity,it is challenging to accurately characterize their structure and properties.An important means to reach such a goal is computational simu...Nanosystems play an important role in many applications.Due to their complexity,it is challenging to accurately characterize their structure and properties.An important means to reach such a goal is computational simulation,which is grounded on ab initio electronic structure calculations.Low scaling and accurate electronic-structure algorithms have been developed in recent years.Especially,the efficiency of hybrid density functional calculations for periodic systems has been significantly improved.With electronic structure information,simulation methods can be developed to directly obtain experimentally comparable data.For example,scanning tunneling microscopy images can be effectively simulated with advanced algorithms.When the system we are interested in is strongly coupled to environment,such as the Kondo effect,solving the hierarchical equations of motion turns out to be an effective way of computational characterization.Furthermore,the first principles simulation on the excited state dynamics rapidly emerges in recent years,and nonadiabatic molecular dynamics method plays an important role.For nanosystem involved chemical processes,such as graphene growth,multiscale simulation methods should be developed to characterize their atomic details.In this review,we review some recent progresses in methodology development for computational characterization of nanosystems.Advanced algorithms and software are essential for us to better understand of the nanoworld.展开更多
Objective: To sum up experiences and lessons about management of soft-tissue reconstruction in open tibial fracture over a 6-year period. Methods: Twenty-two flap reconstructions were performed to treat soft-tissue de...Objective: To sum up experiences and lessons about management of soft-tissue reconstruction in open tibial fracture over a 6-year period. Methods: Twenty-two flap reconstructions were performed to treat soft-tissue defect of 22 patients with open tibial fracture Type IIIB (Gustilo) from 1993 to 1998. The cases were analyzed and discussed retrospectively after follow up of 12-61 months. Results: The size of the flap ranged from 6.6 cm 2 to 28.18 cm 2 and the rate of flap failure was 13.6%. Besides, 3 partial necrosis and 2 postoperative infections occurred in this series. Conclusions: For soft tissue defect of delayed open tibial fracture Type IIIB, flap reconstruction is still an optimal option. The experiences we obtained are ① to design a triangular skin extension or a small Z-plasty over the pedicle to reduce the flap tension; ② to select a unilateral external fixation to provide convenience for any secondary manipulation; and ③ to use serial debridement to diminish flap failure.展开更多
基金Opening Fund of State Key Laboratory of Fire Science,University of Science and Technology of China(No.HZ2011-KF04)
文摘Water mist technology provides efficient firefighting performance while there is still room for improvement. So varieties of additives have been studied in recent years both at home and abroad. The self-made additives are used to compare the firefighting performance of diesel and heptane fire in open space. By adjusting the concentration of substance in the additives and conducting the experiment under the pressure of 0.3 MPa,0.5 MPa and 0.7 MPa,extinguish time and temperature are measured in the experiment. Through the experiments using different fuels,it can be found when the fuel is heptane that has a lower ignition point and a higher evaporation rate, the water mist additive can still significantly improve the firefighting performance. According to the data based on different concentrations of fluorinated surfactants,we find that fluorinated surfactants are the main substance to improve the performances by changing physical property of water mist. Optimal proportion of the additives for firefighting performance is found by experiment results.
基金Project(40571032) supported by the National Natural Science Foundation of ChinaProject(2006G011-B-3) supported by Science Studies and Development Plan Foundation of Railway Ministry
文摘To investigate the frost-heave properties of silty clay under the combination action of seasonal freezing and artificial freezing, and verify the feasibility of combined freezing, eight combined freezing experiments were performed on silty clay with water content (mass fraction) of 23.5% and 28.0%, through developed frost-heave test apparatus, in closed or open system. Two sorts of freezing temperature models, namely, constant and sine models, were applied to artificial freezing. The experimental results indicate that the frost-heave degree in seasonal freezing stage accounts for over 90% of the total in open system and it is up to 95% in closed system; the change of artificial sine-freezing temperature has no influence on the frost-heave degree in closed system, however, slight influence in open system. It is found that the variation of temperature gradient of sine-freezing specimen lags behind that of sine-freezing temperature with half phase; sine-freezing temperature model can reduce frost-heave degree of soil. Brand new technology is proposed for the application of artificial ground freezing and new study field of artificial freezing is created.
基金supported by the Ministry of Science and Technology(No.2016YFA0200604)。
文摘Nanosystems play an important role in many applications.Due to their complexity,it is challenging to accurately characterize their structure and properties.An important means to reach such a goal is computational simulation,which is grounded on ab initio electronic structure calculations.Low scaling and accurate electronic-structure algorithms have been developed in recent years.Especially,the efficiency of hybrid density functional calculations for periodic systems has been significantly improved.With electronic structure information,simulation methods can be developed to directly obtain experimentally comparable data.For example,scanning tunneling microscopy images can be effectively simulated with advanced algorithms.When the system we are interested in is strongly coupled to environment,such as the Kondo effect,solving the hierarchical equations of motion turns out to be an effective way of computational characterization.Furthermore,the first principles simulation on the excited state dynamics rapidly emerges in recent years,and nonadiabatic molecular dynamics method plays an important role.For nanosystem involved chemical processes,such as graphene growth,multiscale simulation methods should be developed to characterize their atomic details.In this review,we review some recent progresses in methodology development for computational characterization of nanosystems.Advanced algorithms and software are essential for us to better understand of the nanoworld.
文摘Objective: To sum up experiences and lessons about management of soft-tissue reconstruction in open tibial fracture over a 6-year period. Methods: Twenty-two flap reconstructions were performed to treat soft-tissue defect of 22 patients with open tibial fracture Type IIIB (Gustilo) from 1993 to 1998. The cases were analyzed and discussed retrospectively after follow up of 12-61 months. Results: The size of the flap ranged from 6.6 cm 2 to 28.18 cm 2 and the rate of flap failure was 13.6%. Besides, 3 partial necrosis and 2 postoperative infections occurred in this series. Conclusions: For soft tissue defect of delayed open tibial fracture Type IIIB, flap reconstruction is still an optimal option. The experiences we obtained are ① to design a triangular skin extension or a small Z-plasty over the pedicle to reduce the flap tension; ② to select a unilateral external fixation to provide convenience for any secondary manipulation; and ③ to use serial debridement to diminish flap failure.
