A new type of explosive ink formulation that can be quickly cured was prepared with unsaturated polyester as binder,styrene as active monomer,2,4,6-trimethylbenzoyl-diphenylphosphine oxide as photoinitiator,and hexani...A new type of explosive ink formulation that can be quickly cured was prepared with unsaturated polyester as binder,styrene as active monomer,2,4,6-trimethylbenzoyl-diphenylphosphine oxide as photoinitiator,and hexanitrohexaazaisowurtzitane(CL-20)as the main explosive.Then the explosive inkdirect writing technology was used to charge the micro-sized energetic devices,the curing mechanism of the explosive ink was discussed,and the microstructure,safety performance and explosive transfer performance of the explosive ink molded samples were tested and analyzed.Results indicate that the composite material has a fast curing molding speed,its hardness can reach 2H within 8 min.The crystal form of CL-20 in the molded sample is still type.The CL-20 based UV-curing explosive ink formulation has good compatibility,its apparent activation energy is increased by about 3.5 kj/mol.The composite presents a significant reduction in impact sensitivity and its characteristic drop height can reach 39.8 cm,whichis about 3 times higher than the raw material.When the line width of charge is 1.0 mm,the critical thickness of the explosion can reach 0.015 mm,and the explosion velocity is 7129 m/s when the charge density is 1.612 g/cm^(3).展开更多
In the context of mediastinal emphysema/pneumomediastinum,the main aetiologies are associated with oesophageal perforation,lung pathology or post head and neck surgery related.The main way to differentiate the patholo...In the context of mediastinal emphysema/pneumomediastinum,the main aetiologies are associated with oesophageal perforation,lung pathology or post head and neck surgery related.The main way to differentiate the pathologies would be through Computed Tomographic Imaging of the Thorax and abdomen with oral and intravenous contrast in the context of triple phase imaging.The causes of pneumomediastinum should be differentiated between traumatic and non-traumatic.Oesophageal perforation(Boerhaave syndrome)is associated with Mackler’s triad in upto 50%of patients(severe retrosternal chest pain,pneumomediastinum,mediastinitis).Whereas in cases of lung pathology this can be associated with pneumothorax and pleural effusion.展开更多
Recently, virtualization has become more and more important in the cloud computing to support efficient flexible resource provisioning. However, performance interference among virtual machines(VMs) has become a challe...Recently, virtualization has become more and more important in the cloud computing to support efficient flexible resource provisioning. However, performance interference among virtual machines(VMs) has become a challenge which may affect the effectiveness of resource provisioning. In a virtual cluster which runs the Map Reduce applications, the performance interference can also affect the performance of the Map and Reduce tasks and thus cause a performance degradation of the Map Reduce job. Accordingly, this paper presents a Map Reduce scheduling framework to mitigate this performance degradation caused by the performance interference. The framework includes a performance interference prediction module and an interference aware scheduling algorithm. To verify its effectiveness, we have done a set of experiments on a 24-node virtual Map Reduce cluster. The experiments illustrate that the proposed framework can achieve a performance improvement in the virtualized environment compared with other Map Reduce schedulers.展开更多
Ileal perforation of typhus origin is a common and serious complication of typhoid fever in tropical environments. It is one of the main causes of morbidity in surgery in Mali. However, it would be preventable if salm...Ileal perforation of typhus origin is a common and serious complication of typhoid fever in tropical environments. It is one of the main causes of morbidity in surgery in Mali. However, it would be preventable if salmonellosis were properly managed upstream, and if our living environments were cleaned up. The purpose of this study is to report on the experience of the Kati UHC General Surgery Department in the management of peritonitis by typhic perforation and to assess its prognosis. Patients and Method: This is a retrospective descriptive study that took place from January 2007 to December 2020 in the General Surgery department of the Hospitalo-University BSS Center of Kati (Mali). We have included patients who have undergone peritonitis with confirmed typhic ileal perforation with laparotomy. The other etiologies of peritonitis by ileal perforation were not retained. Results: In 14 years, we collected 89 cases of peritonitis by typhic ileal perforation. It accounted for 3.14% (89/2829) of surgical procedures, 37.5% (89/1181) of visceral surgical emergencies and 27.6% (89/322) of all acute peritonitis causes combined. There were 70 men against 29 women;the sex ratio was 2.4 with an average age of 25.8 years (extremes 8 years to 65 years). Anastomosis resetions (ileo ileal and ileocolic) predominated in 71.8% of patients. However, the ileo stoma was performed in 5.6%. A significant relationship (p 0.05) was observed between high mortality and MPI score > 26. Morbidity was 39.4% with mortality of 15.7%. The average length of stay in hospital was 12.2 days. Conclusion: Typhoid ileal perforation is common in young male adolescents in visceral surgery. This pathology generates significant morbidity. However with the extension of hand washing after Ebola disease its frequency has dropped.展开更多
ZA27 alloy has the best performance and the widest applications in high aluminum zinc based die casting alloy series. One of its main applica-tions is used as abrasion resistant alloy,instead of nonferrous alloys such...ZA27 alloy has the best performance and the widest applications in high aluminum zinc based die casting alloy series. One of its main applica-tions is used as abrasion resistant alloy,instead of nonferrous alloys such as copper alloy.The frictional wear p展开更多
虚拟同步发电机(virtual synchronous generator,VSG)在引入同步机二阶转子运动方程,增大电力系统等效惯量的同时,也引入了同步发电机的振荡特性,有功低频振荡等动态稳定性问题也随之而来。引入调速侧电力系统稳定器(governor power sys...虚拟同步发电机(virtual synchronous generator,VSG)在引入同步机二阶转子运动方程,增大电力系统等效惯量的同时,也引入了同步发电机的振荡特性,有功低频振荡等动态稳定性问题也随之而来。引入调速侧电力系统稳定器(governor power system stabilizer,GPSS)能有效抑制VSG的功率低频振荡,但其在超调量及调节时间方面的控制效果仍有待提高。通过建立VSG的小信号模型从极点配置角度分析其稳定性,揭示基于GPSS的VSG控制策略在功率动态响应上存在较高超调和较长调节时间的原因。基于此,参考GPSS控制思想,提出了一种基于超前滞后环节附加前馈阻尼补偿的虚拟同步发电机控制策略。并从理论上分析验证了所提控制策略在不影响系统稳态特性的前提下,能够提供调整自由度更高的正阻尼,在有效地抑制功率超调的同时提高了系统的调节速度,从而更好地抑制了有功功率的低频振荡。最后通过MATLAB/Simulink进行对比仿真,仿真结果与理论分析结果一致,证明了所提控制策略的正确性和有效性。展开更多
基金Equipment Development Department of China(61406190401).
文摘A new type of explosive ink formulation that can be quickly cured was prepared with unsaturated polyester as binder,styrene as active monomer,2,4,6-trimethylbenzoyl-diphenylphosphine oxide as photoinitiator,and hexanitrohexaazaisowurtzitane(CL-20)as the main explosive.Then the explosive inkdirect writing technology was used to charge the micro-sized energetic devices,the curing mechanism of the explosive ink was discussed,and the microstructure,safety performance and explosive transfer performance of the explosive ink molded samples were tested and analyzed.Results indicate that the composite material has a fast curing molding speed,its hardness can reach 2H within 8 min.The crystal form of CL-20 in the molded sample is still type.The CL-20 based UV-curing explosive ink formulation has good compatibility,its apparent activation energy is increased by about 3.5 kj/mol.The composite presents a significant reduction in impact sensitivity and its characteristic drop height can reach 39.8 cm,whichis about 3 times higher than the raw material.When the line width of charge is 1.0 mm,the critical thickness of the explosion can reach 0.015 mm,and the explosion velocity is 7129 m/s when the charge density is 1.612 g/cm^(3).
文摘In the context of mediastinal emphysema/pneumomediastinum,the main aetiologies are associated with oesophageal perforation,lung pathology or post head and neck surgery related.The main way to differentiate the pathologies would be through Computed Tomographic Imaging of the Thorax and abdomen with oral and intravenous contrast in the context of triple phase imaging.The causes of pneumomediastinum should be differentiated between traumatic and non-traumatic.Oesophageal perforation(Boerhaave syndrome)is associated with Mackler’s triad in upto 50%of patients(severe retrosternal chest pain,pneumomediastinum,mediastinitis).Whereas in cases of lung pathology this can be associated with pneumothorax and pleural effusion.
基金supported in part by the National Key Technology R&D Program of the Ministry of Science and Technology (2015BAH09F02, 2015BAH47F03)National Natural Science Foundation of China(60903008,61073062)the Fundamental Research Funds for the Central Universities(N130417002, N130404011)
文摘Recently, virtualization has become more and more important in the cloud computing to support efficient flexible resource provisioning. However, performance interference among virtual machines(VMs) has become a challenge which may affect the effectiveness of resource provisioning. In a virtual cluster which runs the Map Reduce applications, the performance interference can also affect the performance of the Map and Reduce tasks and thus cause a performance degradation of the Map Reduce job. Accordingly, this paper presents a Map Reduce scheduling framework to mitigate this performance degradation caused by the performance interference. The framework includes a performance interference prediction module and an interference aware scheduling algorithm. To verify its effectiveness, we have done a set of experiments on a 24-node virtual Map Reduce cluster. The experiments illustrate that the proposed framework can achieve a performance improvement in the virtualized environment compared with other Map Reduce schedulers.
文摘Ileal perforation of typhus origin is a common and serious complication of typhoid fever in tropical environments. It is one of the main causes of morbidity in surgery in Mali. However, it would be preventable if salmonellosis were properly managed upstream, and if our living environments were cleaned up. The purpose of this study is to report on the experience of the Kati UHC General Surgery Department in the management of peritonitis by typhic perforation and to assess its prognosis. Patients and Method: This is a retrospective descriptive study that took place from January 2007 to December 2020 in the General Surgery department of the Hospitalo-University BSS Center of Kati (Mali). We have included patients who have undergone peritonitis with confirmed typhic ileal perforation with laparotomy. The other etiologies of peritonitis by ileal perforation were not retained. Results: In 14 years, we collected 89 cases of peritonitis by typhic ileal perforation. It accounted for 3.14% (89/2829) of surgical procedures, 37.5% (89/1181) of visceral surgical emergencies and 27.6% (89/322) of all acute peritonitis causes combined. There were 70 men against 29 women;the sex ratio was 2.4 with an average age of 25.8 years (extremes 8 years to 65 years). Anastomosis resetions (ileo ileal and ileocolic) predominated in 71.8% of patients. However, the ileo stoma was performed in 5.6%. A significant relationship (p 0.05) was observed between high mortality and MPI score > 26. Morbidity was 39.4% with mortality of 15.7%. The average length of stay in hospital was 12.2 days. Conclusion: Typhoid ileal perforation is common in young male adolescents in visceral surgery. This pathology generates significant morbidity. However with the extension of hand washing after Ebola disease its frequency has dropped.
文摘ZA27 alloy has the best performance and the widest applications in high aluminum zinc based die casting alloy series. One of its main applica-tions is used as abrasion resistant alloy,instead of nonferrous alloys such as copper alloy.The frictional wear p
文摘虚拟同步发电机(virtual synchronous generator,VSG)在引入同步机二阶转子运动方程,增大电力系统等效惯量的同时,也引入了同步发电机的振荡特性,有功低频振荡等动态稳定性问题也随之而来。引入调速侧电力系统稳定器(governor power system stabilizer,GPSS)能有效抑制VSG的功率低频振荡,但其在超调量及调节时间方面的控制效果仍有待提高。通过建立VSG的小信号模型从极点配置角度分析其稳定性,揭示基于GPSS的VSG控制策略在功率动态响应上存在较高超调和较长调节时间的原因。基于此,参考GPSS控制思想,提出了一种基于超前滞后环节附加前馈阻尼补偿的虚拟同步发电机控制策略。并从理论上分析验证了所提控制策略在不影响系统稳态特性的前提下,能够提供调整自由度更高的正阻尼,在有效地抑制功率超调的同时提高了系统的调节速度,从而更好地抑制了有功功率的低频振荡。最后通过MATLAB/Simulink进行对比仿真,仿真结果与理论分析结果一致,证明了所提控制策略的正确性和有效性。
