The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolyme...The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolymer composite(EGC)is a promising material featured by eco-friendly,fast-setting and strain-hardening characteristics for emergent strengthening and construction.However,the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are uncertain.In this study,laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability,dry shrinkage,and mechanical properties in compression,tension and flexure.The experimental results showed that EGC containing PE fiber exhibited suitable workability,acceptable dry shrinkage and superior mechanical properties compared with other types of fibers.After that,a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical elements.The tests include autoclaved aerated concrete(AAC)masonry walls subjected to vented gas explosion,reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact explosion.It was found that EGC could effectively enhance the blast resistance of structural elements in different scenarios.For AAC masonry walls and panels,with the existence of EGC,the integrity of specimens could be maintained,and their deflections and damage were significantly reduced.For plain concrete slabs,the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.展开更多
The artificial intelligence is applied to the simulation of the automotive air-conditioning system ( AACS )According to the system's characteristics a model of AACS, based on neural network, is developed. Differen...The artificial intelligence is applied to the simulation of the automotive air-conditioning system ( AACS )According to the system's characteristics a model of AACS, based on neural network, is developed. Different control methods of AACS are discussed through simulation based on this model. The result shows that the neural- fuzzy control is the best one compared with the on-off control and conventional fuzzy control method.It can make the compartment's temperature descend rapidly to the designed temperature and the fluctuation is small.展开更多
As an environmentally harmless and feasible alternate refrigerant, CO2 has attracted worldwide attention, especially in the area of automobile air-conditioning (AAC). The thermal property of CO2 and its trans-eritical...As an environmentally harmless and feasible alternate refrigerant, CO2 has attracted worldwide attention, especially in the area of automobile air-conditioning (AAC). The thermal property of CO2 and its trans-eritical refrigeration cycle is very different from that of the traditional CFC or HCFC system. The detailed process of CO2 system thermal cycle design and optimization is described in this paper. System prototype and performance test bench were developed to analyze the performance of the CO2 AAC system.展开更多
Background and Prupose: Antibiotic resistance is a major global health concern. In addition to the existing data on the prevalence of bacterial resistance to antibiotics, there are patchy data on bacterial resistance ...Background and Prupose: Antibiotic resistance is a major global health concern. In addition to the existing data on the prevalence of bacterial resistance to antibiotics, there are patchy data on bacterial resistance to aminoglycosides in Burkina Faso. In this study, we determined the prevalence of aminoglycoside resistance genes in E. coli, including aac(3)-IIc, aac(6)-Ib and armA in Ouagadougou, and determined which antibiotics in this class are most affected by resistance. Material and Methods: This study was conducted on 216 E. coli strains collected from the biomedical analysis laboratories of Saint Camille and Schiphra hospitals. E. coli strains were isolated from pus and urine samples collected between September 2018 and January 2019. Antibiotic susceptibility testing was performed using aminoglycosides, β-lactams, fluoroquinolones, and sulfonamides. Aminoglycoside resistance genes were detected in strains with at least one aminoglycoside resistance gene using conventional/multiplex PCR. Results: Aminoglycoside resistance was observed in 46.8% (101/216) of strains. The resistance rates were respectively 45.37% for Tobramycin, 32.40% for Gentamicin, 14.81% for Kanamycin, 2.31% for Netilmicin, 1.84% for Neomycin, and 0.46% for Amikacin. PCR showed that 86 strains (85.15%) possessed the aac(3)-IIc gene, 71 strains or 70.30%) possessed the aac(6’)-Ib gene, and nine strains (8.91%) possessed the armA gene. Conclusion: Aminoglycoside resistance in pathogenic E. coli strains is mainly due to the presence of the aac(3’)-IIc and aac(6’)-Ib genes. The presence of armA was first reported in Burkina Faso. Netilmicin, Neomycin and Amikacin are good therapeutic options for treating urinary tract and pus-forming infections.展开更多
为解决矿井高压电网在发生单相漏电故障时无法准确、快速选出故障线路的问题,提出了一种基于AAC(Artificial Active Component)的矿井高压漏电保护方法,通过人为增加的有功分量增强故障线路的特征辨识度,以达到正确选线的目的。当单相...为解决矿井高压电网在发生单相漏电故障时无法准确、快速选出故障线路的问题,提出了一种基于AAC(Artificial Active Component)的矿井高压漏电保护方法,通过人为增加的有功分量增强故障线路的特征辨识度,以达到正确选线的目的。当单相漏电故障发生后,谐振接地系统达到稳态时再投入并联电阻,待正确选线并跳闸后再将电阻切除;分析了AAC漏电保护方法在矿井6 kV高压电网漏电保护的适用性。同时基于该方法设计了选择性漏电保护装置,并对其进行了软硬件设计。展开更多
基金National Natural Science Foundation of China(Grant Nos.51908188 and 51938011).
文摘The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolymer composite(EGC)is a promising material featured by eco-friendly,fast-setting and strain-hardening characteristics for emergent strengthening and construction.However,the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are uncertain.In this study,laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability,dry shrinkage,and mechanical properties in compression,tension and flexure.The experimental results showed that EGC containing PE fiber exhibited suitable workability,acceptable dry shrinkage and superior mechanical properties compared with other types of fibers.After that,a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical elements.The tests include autoclaved aerated concrete(AAC)masonry walls subjected to vented gas explosion,reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact explosion.It was found that EGC could effectively enhance the blast resistance of structural elements in different scenarios.For AAC masonry walls and panels,with the existence of EGC,the integrity of specimens could be maintained,and their deflections and damage were significantly reduced.For plain concrete slabs,the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.
文摘The artificial intelligence is applied to the simulation of the automotive air-conditioning system ( AACS )According to the system's characteristics a model of AACS, based on neural network, is developed. Different control methods of AACS are discussed through simulation based on this model. The result shows that the neural- fuzzy control is the best one compared with the on-off control and conventional fuzzy control method.It can make the compartment's temperature descend rapidly to the designed temperature and the fluctuation is small.
文摘As an environmentally harmless and feasible alternate refrigerant, CO2 has attracted worldwide attention, especially in the area of automobile air-conditioning (AAC). The thermal property of CO2 and its trans-eritical refrigeration cycle is very different from that of the traditional CFC or HCFC system. The detailed process of CO2 system thermal cycle design and optimization is described in this paper. System prototype and performance test bench were developed to analyze the performance of the CO2 AAC system.
文摘Background and Prupose: Antibiotic resistance is a major global health concern. In addition to the existing data on the prevalence of bacterial resistance to antibiotics, there are patchy data on bacterial resistance to aminoglycosides in Burkina Faso. In this study, we determined the prevalence of aminoglycoside resistance genes in E. coli, including aac(3)-IIc, aac(6)-Ib and armA in Ouagadougou, and determined which antibiotics in this class are most affected by resistance. Material and Methods: This study was conducted on 216 E. coli strains collected from the biomedical analysis laboratories of Saint Camille and Schiphra hospitals. E. coli strains were isolated from pus and urine samples collected between September 2018 and January 2019. Antibiotic susceptibility testing was performed using aminoglycosides, β-lactams, fluoroquinolones, and sulfonamides. Aminoglycoside resistance genes were detected in strains with at least one aminoglycoside resistance gene using conventional/multiplex PCR. Results: Aminoglycoside resistance was observed in 46.8% (101/216) of strains. The resistance rates were respectively 45.37% for Tobramycin, 32.40% for Gentamicin, 14.81% for Kanamycin, 2.31% for Netilmicin, 1.84% for Neomycin, and 0.46% for Amikacin. PCR showed that 86 strains (85.15%) possessed the aac(3)-IIc gene, 71 strains or 70.30%) possessed the aac(6’)-Ib gene, and nine strains (8.91%) possessed the armA gene. Conclusion: Aminoglycoside resistance in pathogenic E. coli strains is mainly due to the presence of the aac(3’)-IIc and aac(6’)-Ib genes. The presence of armA was first reported in Burkina Faso. Netilmicin, Neomycin and Amikacin are good therapeutic options for treating urinary tract and pus-forming infections.
文摘为解决矿井高压电网在发生单相漏电故障时无法准确、快速选出故障线路的问题,提出了一种基于AAC(Artificial Active Component)的矿井高压漏电保护方法,通过人为增加的有功分量增强故障线路的特征辨识度,以达到正确选线的目的。当单相漏电故障发生后,谐振接地系统达到稳态时再投入并联电阻,待正确选线并跳闸后再将电阻切除;分析了AAC漏电保护方法在矿井6 kV高压电网漏电保护的适用性。同时基于该方法设计了选择性漏电保护装置,并对其进行了软硬件设计。
