Temperature influences of the recoil characteristics for aluminum honeycomb buffer in the tether-net launcher

Fluctuations in outer space's temperature would affect the spacecraft's regular operation.This paper aims to study the temperature influences of the aluminum honeycomb buffer in the tether-net launcher.Firstly,a buffer structure was designed to attenuate the pyroshock generated by the pyrotechnic device.Secondly,the mechanical properties of aluminum honeycomb at different temperatures were obtained through quasi-static compression experiments.Then,the internal ballistic responses of the launcher were gained by the closed bomb tests and the equivalent classical interior ballistic model.Finally,the recoil performance of the launcher with aluminum honeycomb buffer at different temperatures was studied.It is revealed that the aluminum honeycomb crushing force gradually decreases with the temperature increases.The peak pressure,burning rate coefficient and velocity increase while the peak time decreases with the temperature increase for the interior ballistics.For the launcher recoil responses,the average launch recoil decreases if the aluminum honeycomb doesn't enter the dense stage.The impact acceleration,projectile velocity and displacement increase as the temperature increase.The paper spotlights the temperature's influence on the recoil characteristics of the aluminum honeycomb buffer,which provides a new idea for buffering technology of pyrotechnic devices in a complex space environment.

Exploratory COVID-19 death risk score based on basic laboratory tests and physiological clinical measurements

BACKGROUND:In the event of a sudden shortage of medical resources,a rapid,simple,and accurate prediction model is essential for the 30-day mortality rate of patients with COVID-19.METHODS:This retrospective study compared the characteristics of the survivals and non-survivals of 278 patients with COVID-19.Logistic regression analysis was performed to obtain the“COVID-19 death risk score”(CDRS)model.Using the area under the receiver operating characteristic(AUROC)curve and Hosmer-Lemeshow goodness-of-fit test,discrimination and calibration were assessed.Internal validation was conducted using a regular bootstrap method.RESULTS:A total of 63(22.66%)of 278 included patients died.The logistic regression analysis revealed that high-sensitivity C-reactive protein(hsCRP;odds ratio[OR]=1.018),D-dimer(OR=1.101),and respiratory rate(RR;OR=1.185)were independently associated with 30-day mortality.CDRS was calculated as follows:CDRS=−10.245+(0.022×hsCRP)+(0.172×D-dimer)+(0.203×RR).CDRS had the same predictive effect as the sequential organ failure assessment(SOFA)and“confusion,uremia,respiratory rate,blood pressure,and age over 65 years”(CURB-65)scores,with AUROCs of 0.984 for CDRS,0.975 for SOFA,and 0.971 for CURB-65,respectively.And CDRS showed good calibration.The AUROC through internal validations was 0.980(95%confidence interval[CI]:0.965-0.995).Regarding the clinical value,the decision curve analysis of CDRS showed a net value similar to that of CURB-65 in this cohort.CONCLUSION:CDRS is a novel,efficient and accurate prediction model for the early identification of COVID-19 patients with poor outcomes.Although it is not as advanced as the other models,CDRS had a similar performance to that of SOFA and CURB-65.

A short review on the role of alloying elements in duplex stainless steels

Duplex stainless steels consisting of ferrite and austenite are widely used due to their excellent mechanical properties and corrosion resistance.Compared with ferritic stainless steels,duplex stainless steels have better plasticity,toughness,and welding performance.They also possess higher strength and better resistance to stress,pitting,and crevice corrosion than austenitic stainless steels.In addition to the above-mentioned properties,there are cost-saving advantages in duplex stainless steels due to their lower nickel content.Today,the types of duplex stainless steel are mainly divided into four categories:lean duplex stainless steel,standard duplex stainless steel,super duplex stainless steel,and hyper duplex stainless steel.Alloying design of duplex stainless steel is an important strategy to achieve high performance.In the last two decades,significant progress has been made in both theoretical calculations and experiments.By adjusting alloying elements such as chromium,nickel,molybdenum,nitrogen,copper,tungsten and rare earth,etc.,the mechanical properties and/or corrosion resistance of the duplex stainless steels can be further improved.Summarizing the comprehensive progress of alloying design of duplex stainless steel is of great significance in providing a data basis for establishing the corresponding relationship between chemical compositions and properties.Therefore,this paper reveals the specific roles of alloying elements in the duplex stainless steels and provides a reference for alloying design with different performance requirements.