Search

Stroke, also known as a cerebrovascular accident (CVA), is the fifth leading cause of death for Americans, accounting for 140,000 lives each year (“Stroke facts,” 2017). CVA marks 1 out of every 20 deaths and nearly 75% of all strokes occur in people aged 65 years and above (Centers for disease control,” 2017). As a leading cause of long-term disability, stroke can have devastating effects on patients and their caregivers. Despite a number of emerging technologies that could potentially be helpful in the prevention, evaluation, and rehabilitation of strokes, typically, such technologies are limited and only considered for millennials. Similarly, at the present time, there is not a single platform designed specifically for stroke management. This makes access to relevant CVA information for baby boomers and the elderly challenging and the potential edification process rather inefficient. The key objective of this review is to identify and discuss effective technologies that can assist baby boomers, born between 1946 and 1964 in the United States, to manage CVA and further explore possible concerns of baby boomers associated with awareness and accessibility of the aforementioned technologies.

Currently, toxic and carcinogenic hydrazine propellants are commonly used in spacecraft propulsion. These propellants impose distinctive environmental challenges and consequential hazardous conditions. With an increasing level of future space activities and applications, the significance of greener space propulsion becomes even more pronounced. In this article, a selected number of promising green space propellants are reviewed and investigated for various space missions. In-depth system studies in relation to the aforementioned propulsion architectures further unveil possible approaches for advanced green propulsion systems of the future.

Purpose – This article aims to investigate a selected number of liquid hydrogen storage tank parameters in a turboelectric distributed propulsion concept. Design/methodology/approach – In this research study, tank structure, tank geometry, tank materials and additional physical phenomenon such as hydrogen boil-off and permeation are considered. A parametric analysis of different insulation foams is also performed throughout the design process of a lightweight liquid hydrogen storage tank. Findings – Based on the mass of boil-off and foam weight, phenolic foam exhibited better characteristics amongst the five foam insulation materials considered in this particular study. Practical implications – Liquid hydrogen occupies 4.2 times the volume of jet fuel for the same amount of energy. This suggests that a notable tank size is expected. Nonetheless, as jet fuel weighs 2.9 times more than liquid hydrogen for the same amount of energy, this reduced weight aspect partly compensates for the increased tank size. O...

Distributed propulsion is one of the revolutionary candidates for future aircraft propulsion. In this journal article, the potential role of distributed propulsion technology in future aviation is investigated. Following a historical journey that revisits distributed propulsion technology in unmanned air vehicles and military aircraft, features of this specific technology are highlighted in synergy with an electric aircraft concept and a first-of-a-kind comparison to commercial aircraft employing distributed propulsion arrangements. In light of propulsion–airframe integration and complementary technologies such as boundary layer ingestion, thrust vectoring and circulation control, transpired opportunities and challenges are addressed in addition to a number of identified research directions proposed for future aircraft. The motivation behind enhanced means of communication between engineers, researchers and scientists has stimulated a novel proposed definition for the distributed propulsion technology in aviation and is presented herein.

The needed shift in next generation aircraft design is expected to bring novel concepts for civil aviation as the jet-flap wing. The aircraft efficiency improvements with the jet-flap wing directs its use for future aircraft designs reinforced by the tendency for more synergistic systems as active flow control, boundary layer ingestion and distributed propulsion, making the jet-flap wing a very suitable option for the latter concept. The analysis carried out in this paper is aimed at the application of the jet-flap wing concept for manoeuvrability and cruise efficiency improvement of an airliner. A 2D computational model of a jet-flapped transonic airfoil is developed in order to assess the jet-flap wing technology for a commercial aircraft at cruise conditions. This paper provides an insight into the parameters that affect the performance of a jet-flap under various flight conditions. To do this, a general parametrical analysis is performed, studying numerically the influences of main flow parameters like Mach number, Reynolds number, angle of attack, jet deflection angle and jet thickness. Changes in pressure distribution and flow circulation around the airfoil yield strong modifications in lift and drag due to jet angle variation. Improvements are encountered in the performance of an airfoil with a jet-flap system compared with a standard airfoil with no jet. Enhancements in lift and reduction in drag, as well as an increase of the lift-to-drag ratio is possible with a proper combination of the jet deflection and the angle of attack of the airfoil. In summary, this paper shows the conditions under which the benefits of the jet-flapped wing, for lift enhancement and manoeuvrability as an active flow control are promising.

PurposeThe purpose of this paper is to outline the potential usage of ceramic engines in combination with other technologies as a possible propulsion contender for future aerospace applications.Design/methodology/approachThe possibility of enabling novel propulsion systems in aerospace engineering is examined through a multilateral review study concerning ceramic engines and a proposed design approach. In view of the benefits and challenges of employing ceramic engines as possible candidates for the sustainable solutions of the future, a fundamental design proposal is presented for a conceptual generic unmanned air vehicle (GUAV).FindingsThe findings of this article identify a number of useful scenarios for future ceramic engine applications and considerations.Research limitations/implicationsIt is imperative to emphasize that this conceptual article solely sheds light on a limited number of key ideas associated with ceramic engines and their possible applications. Thus, many new areas may emerge and impact the application of ceramic engines in light of more in‐depth conceptual studies.Practical implicationsImplications of ceramic engine utilization in aeronautical applications may result in enhanced performance characteristics and less operational costs. Further implications could possibly be extended to various naval/automotive applications and new configurations of transportation vehicles.Social implicationsThe paper aims to generate an interest amongst younger individuals and environmental aware enthusiasts to consider ceramic engines for transportation applications to a greater extent than before.Originality/valueThe implementation of this particular conceptual design results in a synergistic ceramic engine combination with a hybrid airship design in novel aeronautical applications.

This paper highlights the role of distributed propulsion technology for future commercial aircraft. After an initial historical perspective on the conceptual aspects of distributed propulsion technology and a glimpse at numerous aircraft that have taken distributed propulsion technology to flight, the focal point of the review is shifted towards a potential role this technology may entail for future commercial aircraft. Technological limitations and challenges of this specific technology are also considered in combination with an all electric aircraft concept, as means of predicting the challenges associated with the design process of a next generation commercial aircraft.

Heat transfer coefficients are experimentally determined in various trailing-edge cooling channels. A rectangular channel (AR = 3:1) with fully developed flow is used as a baseline for the study, with the Reynolds number varying from 20,000 to 80,000. The heat transfer coefficients in this channel are compared with those in a similar rectangular channel with coolant extraction, which would likely be encountered in a trailing-edge cooling passage. The heat transfer trends in the rectangular channel are compared with those obtained in a passage with a trapezoidal (or wedge-shaped) cross section. The heat transfer coefficients are also obtained in the channel without coolant extraction and with extraction from the narrow side of the channel. The effect of V-shaped rib turbulators is also considered in the rectangular and trapezoidal cooling passages. In addition, the effect of entrance condition is considered with the wedge-shaped channel. Heat transfer coefficients obtained with hydrodynamically developed flow are compared with those with flow through a contraction into the heated section of the channel. In the rectangular channel without ejection, the heat transfer coefficients are uniform across the span of the channel; however, with coolant ejection, the heat transfer coefficients increase near the ejection slots. In addition, in the trapezoidal channels, the heat transfer coefficients are uniform across the cross section of the smooth channel. When coolant is extracted for trailing-edge ejection, the outer surface sees the most significant heat transfer enhancement. The outer surface of the smooth trapezoidal channel is most profoundly affected by the entrance condition, and the effect of the entrance condition is marginal in trapezoidal channels with ribs and ejection.

Sustainable aerospace engineering practices in the 21st century constantly entail identification of innovative technical solutions and infusion of environmental friendly technologies. This paper provides an overview of past, current and the potential future role of Lithium-Ion batteries within the broader aerospace sector. Specifically, crucial areas such as technical and economic challenges associated with Lithium-Ion batteries are addressed for the purposes of assisting system integrators with fundamental discussions revolving around Lithium-Ion batteries in a multitude of aerospace settings. In this study, two specific examples of Lithium-Ion battery development across distinctly different platforms also provide additional insight about the role of Lithium-Ion batteries in future aerospace applications.

NASA has chosen the Sunjammer Solar Sail Demonstrator mission as one of its Technology Demonstration Missions (TDMs). Named after a short story written by Sir Arthur C. Clarke, L·Garde Inc. of Tustin, California, is developing the solar sail to demonstrate propellantless in-space propulsion and novel capabilities of solar sail navigation. For this program, L·Garde and Applied Defense Solutions (ADS) began development of a navigation plan to enable the Sunjammer Solar Sail Demonstrator to navigate to an artificial Lagrange orbit (ALO) located sunward of the sun-Earth L1 Lagrange point. This orbit and related ones that position a sail out of the ecliptic plane are useful for space weather, remote sensing, and communications. This paper describes the development efforts made in calibrating a real non-ideal sail, determining orbit parameters in the presence of significant solar radiation pressure, and planning sail steering maneuvers to follow a desired trajectory to a desired orbit destination. With flight opportunities in development after a series of ground deployment and qualification tests in 2015 and 2016, demonstration of these significant cutting-edge technologies is right around the corner and will initiate a new era of space exploration.

Solar sails represent one of the advanced propulsion systems of the 21 st century. Despite the propellantless and effectively infinite specific impulse features of these space propulsion concepts, solar sails have consistently remained rather unknown to the general public. This paper aims to portray a number of historical milestones with regards to the evolution of solar sails and equally seeks to shed light on selected design features of the Sunjammer solar sail. Moreover, the objective of this study is also to revisit solar sails from a broader vantage point and to partially highlight the interest these propulsion concepts have generated over the years.

The thermal performance is measured in a rectangular channel (AR = 3:1) with rib turbulators oriented at 45° to the mainstream flow. Ribs are placed on one of the wide walls, while heat transfer coefficients are also measured on a single smooth, narrow wall. The heat transfer enhancement is combined with the frictional losses to evaluate the benefit of turbulator width. Square ribs (w/e = 1) with a rib pitch–to–height (P/e) ratio of 8 serves as the baseline configuration. The rib width, w, is varied while the rib height, e, remains constant. Rib aspect ratios (w/e) of 1, 2, 3, and 4 are considered. In addition, the distance between the ribs is varied to consider the combined effect of rib width and rib spacing. As the width of the ribs is changing, the physical distance between the ribs, l , is varied, and four rib spacings are considered (l /e = 2.6, 6.6 [baseline corresponding to P/e = 8], 10.6, and 14.6). The thermal performance is measured in the 3:1 channel at Reynolds numbers of 10000, 30000, 50000, and 70000. Results indicate increasing the rib width is effective to increase the thermal performance of a cooling passage. However, the rib width and spacing must be varied in conjunction with one another to optimize the thermal performance.Copyright © 2008 by ASME