Damage tolerance and arrest characteristics of pressurized graphite/epoxy tape cylinders

An investigation of the damage tolerance and damage arrest characteristics of internally-pressurized graphite/epoxy tape cylinders with axial notches was conducted. An existing failure prediction methodology, developed and verified for quasi-isotropic graphite/epoxy fabric cylinders, was investigated for applicability to general tape layups. In addition, the effect of external circumferential stiffening bands on the direction of fracture path propagation and possible damage arrest was examined. Quasi-isotropic (90/0/plus or minus 45)s and structurally anisotropic (plus or minus 45/0)s and (plus or minus 45/90)s coupons and cylinders were constructed from AS4/3501-6 graphite/epoxy tape. Notched and unnotched coupons were tested in tension and the data correlated using the equation of Mar and Lin. Cylinders with through-thickness axial slits were pressurized to failure achieving a far-field two-to-one biaxial stress state. Experimental failure pressures of the (90/0/plus or minus 45)s cylinders agreed with predicted values for all cases but the specimen with the smallest slit. However, the failure pressures of the structurally anisotropic cylinders, (plus or minus 45/0)s and (plus or minus 45/90)s, were above the values predicted utilizing the predictive methodology in all cases. Possible factors neglected by the predictive methodology include structural coupling in the laminates and axial loading of the cylindrical specimens. Furthermore, applicability of the predictive methodology depends on the similarity of initial fracture modes in the coupon specimens and the cylinder specimens of the same laminate type. The existence of splitting which may be exacerbated by the axial loading in the cylinders, shows that this condition is not always met. The circumferential stiffeners were generally able to redirect fracture propagation from longitudinal to circumferential. A quantitative assessment for stiffener effectiveness in containing the fracture, based on cylinder radius, slit size, and bending stiffnesses of the laminates, is proposed

Blockchains, Smart Contracts, and the Future of the Judiciary

The blockchain distributed ledger technology, evolved through the new array of cryptocurrency offerings, touts security, trust, and expediency features which have fostered the growth of smart contracts. Unlike traditional written agreements, smart contracts are coded to execute based on certain algorithms and digitally-defined events; consequently, upon satisfaction of specified criteria, payment is immediate, and usually effected through the cryptocurrency of the platform on which the smart contract is based. However, because a smart contract is self-executing, it may be more difficult to unwind in the event of a dispute, especially when most judges are not versed in the language of computer coding. This article will look at the growth of reliance on blockchain technology and the increasing prevalence of smart contracts, and will then explore some current, and hypothesized, options for decision-making in the event of a smart contract dispute, such as platform-embedded arbitration, a dedicated international court of the blockchain, crowd-sourced juries through which a decision is made by gaming theory, and even the evolution of artificial intelligence to transition the role of judge to a computer program

Effects of designated leadership and team-size on cardiopulmonary resuscitation: The Basel-Washington SIMulation (BaWaSim) trial.

© 2018 Elsevier Inc. Objective: During cardiopulmonary resuscitation (CPR), it remains unclear whether designating an individual person as team leader compared with emergent leadership results in better team performance. Also, the effect of CPR team size on team performance remains understudied. Methods: This randomized-controlled trial compared designated versus emergent leadership and size of rescue team (3 vs 6 rescuers) on resuscitation performance. Results: We included 90 teams with a total of 408 students. No difference in mean (±SD) hands-on time (seconds) were observed between emergent leadership (106 ± 30) compared to designated leadership (103 ± 27) groups (adjusted difference − 2.97 (95%CI -15.75 to 9.80, p = 0.645), or between smaller (103 ± 30) and larger teams (106 ± 26, adjusted difference 3.53, 95%CI -8.47 to 15.53, p = 0.56). Emergent leadership groups had a shorter time to circulation check and first defibrillation, but the quality of CPR based on arm and shoulder position was lower. No differences in CPR quality measures were observed between smaller and larger teams. Conclusions: Within this international US/Swiss trial, leadership designation and larger team size did not improve hands-on time, but emergent leadership teams initiated defibrillation earlier. Improvements in performance may be more likely to be achieved by optimization of emergent leadership than increasing the size of cardiac arrest teams

Effects of designated leadership and team-size on cardiopulmonary resuscitation: The Basel-Washington SIMulation (BaWaSim) trial

© 2018 Elsevier Inc. Objective: During cardiopulmonary resuscitation (CPR), it remains unclear whether designating an individual person as team leader compared with emergent leadership results in better team performance. Also, the effect of CPR team size on team performance remains understudied. Methods: This randomized-controlled trial compared designated versus emergent leadership and size of rescue team (3 vs 6 rescuers) on resuscitation performance. Results: We included 90 teams with a total of 408 students. No difference in mean (±SD) hands-on time (seconds) were observed between emergent leadership (106 ± 30) compared to designated leadership (103 ± 27) groups (adjusted difference − 2.97 (95%CI -15.75 to 9.80, p = 0.645), or between smaller (103 ± 30) and larger teams (106 ± 26, adjusted difference 3.53, 95%CI -8.47 to 15.53, p = 0.56). Emergent leadership groups had a shorter time to circulation check and first defibrillation, but the quality of CPR based on arm and shoulder position was lower. No differences in CPR quality measures were observed between smaller and larger teams. Conclusions: Within this international US/Swiss trial, leadership designation and larger team size did not improve hands-on time, but emergent leadership teams initiated defibrillation earlier. Improvements in performance may be more likely to be achieved by optimization of emergent leadership than increasing the size of cardiac arrest teams