This article presents the compression response and energy absorption capabilities of novel carbon fiber reinforced thermoplastic honeycombs manufactured through vacuum assisted resin transfer molding technique. The composite honeycombs were fabricated in a steel mold having removable hexagonal rings inside each honeycomb cell. The novel honeycombs exhibited compressive strength as high as 39.5 MPa and specific energy absorption values in excess of 50 kJ/kg. It was observed that increasing the fiber weight fraction significantly improved the compressive response of the honeycomb cores. Furthermore, the results showed that the thermoplastic honeycombs exhibited better energy absorption capabilities compared to their epoxy counterparts.
This study explores the potential of Sweeping Jet Actuators as effective flow control devices for bluff body drag reduction. A baseline actuator design installed on Ahmed body in mid plane configuration provides a decrease in base suction resulting in reduced drag. Slight variations in maximum suction pressure reduction are also observed for different internal geometries of the actuator. Sweeping Jet Actuators may be applied as an alternative to steady jet base blowing, provided the location of actuator is such that the detrimental interaction of blown jet with global shear layers is kept minimized.
Our knowledge about Uranus and its moons is scarce. To gain insight into the features of this planet and its satellites, an exploration mission is needed. Uranus axial tilt of 98? requires a prohibitive amount of propellant for insertion into an equatorial orbit. To minimize the cost of the orbit insertion maneuver, a combination of low-thrust (LT) propulsion and gravity assist (GA) at Jupiter is explored. GA is applied at Jupiter en route to Uranus followed by a LT direct optimization approach that minimizes the inclination angle relative to the Uranus equator upon arrival at Uranus. This approach lowers the orbit insertion impulse significantly for the capture into a near-equatorial orbit around Uranus which is required for observation of the features of the planet and its major moons. The LT optimization method, the control-law algorithm, the benefits to the propellant budget, and areas for further progress are presented and discussed.
The recent discoveries made by the Cassini spacecraft have greatly heightened the urge of the scientific community and space agencies in proposing scientific missions to explore Saturn and its moons. This work builds upon the results of two prior contributions regarding the Earth-to-Saturn interplanetary transfer characterized by a low relative arrival speed (1 km/s) and the concept of the lunar cycler to perform an observational tour of the Inner Large Moons of Saturn (Mimas, Enceladus, Tethys, Dione). The main objective here is to minimize propellant cost during the complete mission from the interplanetary arrival at Saturn to the final orbits around the inner moons. In this work, a novel scenario is proposed where a capture around Saturn via gravity assist with Titan is made possible. A sequence of swingbys with Titan, Rhea, and the Inner Large Moons (ILMs) is proposed to bridge between interplanetary space and the lunar tour.
Osteoporosis is the fourth most common chronic disease in the world. Adopting preventative measures and effective self-management interventions helps in improving bone health. Mobile health (mHealth) technologies can play a key role in osteoporosis patient care and self- management. Presently, there is a limited number of mHealth applications available for supporting patients with osteoporosis or healthcare professionals in the research field and in the market place. These applications are in most of the cases poorly designed, have weak performance, and lack evidence-based validation. In this work, we review the available osteoporosis-related mHealth apps and we suggest some guidelines for the development of new, more comprehensive mHealth apps that facilitate self-management of osteoporosis in addition to the decision support and the shared-decision making.
Three-dimensional bioprinting is an emerging fabrication technique in the field of tissue engineering. Extrusion-based bioprinting is one of the widely employed biofabrication techniques; researchers tend to use it because of its simplicity, affordability and scalability. During the extrusion-based bioprinting process, cells are subjected to mechanical forces of different kinds. Among these mechanical forces, shear stress is of a special significance and concern as it is considered the main cause of cell damage/death. This paper covers the principle of extrusion-based bioprinting and the bioinks used. Moreover, it highlights extrusion-based bioprinting induced shear stress, and the relationship between shear stress, cell viability and different material properties and process parameters.
This paper introduces torque-controlled concentric tube robots that are first explored in this field. Currently, integrated actuation mechanisms exhibit challenges in controlling forces at the end-effector. Capstan actuation system featured with its low backlash and reversibility is well-posed to control torque and forces. A 3D model catheter of the proposed torque-controlled approach with an integrated capstan mechanism was created using SolidWorks Software.
Wearable sensors have made an impact on healthcare and medicine by enabling out-of-clinic health monitoring and prediction of pathological events. Further advancements made in wearable sensors and analysis of multimodal signals have been reflected in emotion recognition studies which utilize peripheral including pulse rate, peripheral temperature, and electrodermal activity. The present paper reports on the advantages of applying decision trees and ensemble classifiers for emotion recognition systems using the multimodal physiological signals K-EmoCon dataset. The results indicate that Random Forest performed best compared to the other decision tree classifiers tested, with correctly classified instances up to 74.44% for arousal and up to 80.61% for valence. The use of Random Forest as base classifier for the meta-learner Decorate resulted in 76.16% - accuracy for arousal and 80.20% for valence. This suggests that decision trees and ensemble classification combined with multimodal bio-signals may be a useful model for emotion recognition using imbalanced datasets.
Investigating the anatomical and functional characteristics of fetal brain at different gestational ages helps in understanding the process and helps in detecting pathogenic interventions/abnormalities and further treatments at early stage. This work aims to provide a review of non-invasive fetal electrocardiography(NI-fECG) to analyze fetal brain and neural development at different gestational ages(GA). Results showed that autonomic nervous system(ANS) maturation can be analyzed based on the relationship between fetal heart rate variability(fHRV) and GA where increased fHRV can be observed as GA advances. Maternal-fetal coupling is also an important parameter to study the fetal wellbeing. Based on studies, it was concluded that multivariate approaches provide specific and sensitive scores as different aspects of autonomic control are reflected in different HRV parameters. As NI-fECG is a cost and easily accessible system than other techniques, further exploration of this technique could improve the obstetricians judgement, especially during prematurity.
T cells organize the response of the adaptive immune system; their activation is triggered by antigen-presenting cells. T cells' activation is modulated by two main signaling molecules on APCs surfaces, with recent studies implicating cellular forces in T cell activation. In this work, co-culture and biomimetic models were established. We first disrupted the cytoskeleton of mature dendritic cells (mDC) with cytochalasin B and observed reduced T cell proliferation. We then attempted to mimic mDC and T cell interactions using polyacrylamide (PA) gels with defined stiffness corresponding to mDC (0.2 - 25 kPa), and different ratios of immobilized anti-CD3 (aCD3) and anti-CD28 (aCD28) antibodies. The results showed T cell proliferation was triggered by both aCD3 and aCD28 in a stiffness-dependent manner, with cells cultured on aCD3 gels had significantly higher proliferation. Overall, our biosystem allows distinguishing the impact of biophysical and biochemical signals of APC and T cell interactions in vitro.
