Exploring the thermal stability of lithium-ion cells via accelerating rate calorimetry:A review

Given the importance of lithium-ion cell safety,a comprehensive review on the thermal stability of lithium-ion cells investigated by accelerating rate calorimetry(ARC),is provided in the present work.The operating mechanism of ARC is discussed first,including the usage and the reaction kinetics.Besides that,the thermal stability of the cathode/anode materials at elevated temperatures is revealed by examining the impacts of some significant factors,i.e.,the lithium content,particle size,material density,lithium salt,solvent,additive,binder and initial heating temperature.A comparison of the common cathode materials indicates that the presence of Mn and polyanion could significantly enhance the thermal stability of cathode materials,while the doping of Al also helps to restrain the reactivity.Except for their high capacity,some alloy materials demonstrate more competitive safety than traditional carbon anode materials.Furthermore,the thermal behaviors of full cells under abusive conditions are reviewed here.Due to the sensitivity of ARC to the kinetic parameters,a reaction kinetic modeling can be built on the basis of ARC profiles,to predict the thermal behaviors of cell components and cells.Herein,a shortcircuit modeling is exampled.

Study on single-group dynamics in evacuation considering pre-defined and undeclared leadership

Grouping is a common phenomenon that occurs everywhere.The leader-follower relationship inside groups has often been qualitatively characterized in previous models using simple heuristics.However,a general method is lacking to quantitatively explain leadership in an evacuating group.To understand the evolution of single-group dynamics throughout an evacuation,we developed an extended social force model integrated with a group force.A series of single-group evacuations from a room were simulated.An information-theoretic method,transfer entropy(TE),was applied to detect predefined and undeclared leadership among evacuees.The results showed that the predefined leader was correctly detected by TE,suggesting its capability in measuring leadership based on time series of evacuees’movement information(e.g.,velocity and acceleration).When evacuees were grouped together,TE was higher than when they were alone.Leaders presented a monotonically increasing cumulative influence curve over the investigated period,whereas followers showed a diminishing tendency.We found that leadership emergence correlated with evacuees’spatial positions.The individual located in the foremost part of the group was most likely to become a leader of those in the rear,which concurred with the experimental observations.We observed how a large group split into smaller ones with undeclared leadership during evacuation.These observations were quantitatively verified by TE results.This study provides novel insights into quantifying leadership and understanding single-group dynamics during evacuations.

Patient outcomes after neonatal tracheotomy: A retrospective case-control study

To the Editor:Although reports of neonatal upper airway obstruction in patients in neonatal intensive care units(NICUs)are common,neonatal tracheotomy is rare,possibly due to the small number of patients and the even smaller number of well-equipped hospitals to do a successful operation in neonates.However,despite the extensive efforts of qualified,skilled neonatologists and pediatric otorhinolaryngologists in performing a neonatal tracheotomy,some neonates did not undergo this surgery.When a neonate meets the indications of tracheotomy but his/her parent refuses to do the operation,he/she is facing a higher risk to be discharged against medical advice(DAMA)as per their parents’wish.To explore the preliminary evidence of neonatal tracheotomy in China,as well as to find out the outcome difference between neonates who underwent tracheotomy and those who did not undergo tracheotomy when they met the surgical indications,we conducted a retrospective study.Patients were treated in Beijing Children’s Hospital.Patients were categorized into the tracheotomy group or non-tracheotomy group according to whether their parents signed the tracheotomy consent and finally completed the tracheotomy.This study was approved by the Ethics Committee of Beijing Children’s Hospital,Capital Medical University(No.[2021]-E-139-R)and was registered in the Chinese Clinical Trial Registry(No.ChiCTR2100050720).All parents/guardians of participants provided written informed consent.

The prediction of exit choice using cumulative prospect value

Exit choice is essential for pedestrian safety and evacuation efficiency during the context of an emergency. Cumulative prospect theory is a widespread realistic decision-making theory that can transform choice outcomes and probabilities into subjective terms and integrate them as a parameter of cumulative prospect value (CPV), which determines the decision. The main contribution of this paper is the use of the CPV to predict exit choice. Furthermore, the different decision-making rules including Max, exponential(Expo), and Ratio (i.e., the three variable choice functions) were summarized and examined. This study used a confusion matrix to compare the predicted results with experimental data. Consequently, the parameters of Accuracy and F1-score showed that the predictions from Max and Expo were significantly more realistic while the results from Ratio were much more robust.