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https://www.readbyqxmd.com/read/29431840/hierarchical-carbon-nanotube-composite-yarn-muscles
#1
Yanhui Song, Susheng Zhou, Kaiyun Jin, Jian Qiao, Da Li, Chao Xu, Dongmei Hu, Jiangtao Di, Min Li, Zuoguang Zhang, Qingwen Li
Hybrid smart actuators fabricated using composites of carbon fibers and shape memory polymers have been extensively studied in recent years. However, relatively slow shape recovery has combined with the reset of shape deformation during cycles to restrict their practical use. An electrothermally reversible actuator based on carbon nanotube (CNT) composite yarn containing CNT fiber and thermoplastic polyurethane (TPU) resin with excellent shape memory was investigated in this paper. The combination of CNT yarn and TPU resin considerably amplified the contraction and stability...
February 12, 2018: Nanoscale
https://www.readbyqxmd.com/read/29407279/lebedev-scheme-for-ultrasound-simulation-in-composites
#2
Francisco Hernando Quintanilla, Cara A C Leckey
The growing use of composite materials for aerospace applications has resulted in a need for quantitative nondestructive evaluation (NDE) methods appropriate for characterizing damage in composite components. NDE simulation tools, such as ultrasound models, can aid in enabling optimized inspection methods and establishing confidence in inspection capabilities. In this paper a mathematical approach using the Lebedev Finite Difference (LFD) method is presented for ultrasonic wave simulation in composites. Boundary condition equations for implementing stress-free boundaries (necessary for simulation of NDE scenarios) are also presented...
January 31, 2018: Ultrasonics
https://www.readbyqxmd.com/read/29406737/air-stable-anisotropic-monocrystalline-nickel-nanowires-characterized-using-electron-holography
#3
Glenna L Drisko, Christophe Gatel, Pier-Francesco Fazzini, Alfonso Ibarra, Stefanos Mourdikoudis, Vincent Bley, Katia Fajerwerg, Pierre Fau, Myrtil L Kahn
Nickel is capable of discharging electric and magnetic shocks in aerospace materials thanks to its conductivity and magnetism. Nickel nanowires are especially desirable for such an application as electronic percolation can be achieved without significantly increasing the weight of the composite material. In this work, single-crystal nickel nanowires possessing a homogeneous magnetic field are produced via a metal-organic precursor decomposition synthesis in solution. The nickel wires are 20 nm in width and 1-2 μm in length...
February 6, 2018: Nano Letters
https://www.readbyqxmd.com/read/29403009/carbon-fibers-coated-with-graphene-reinforced-tial-alloy-composite-with-high-strength-and-toughness
#4
Sen Cui, Chunxiang Cui, Jiaqi Xie, Shuangjin Liu, Jiejie Shi
To meet the more rigorous requirement in aerospace industry, recent studies on strengthening and toughening TiAl alloys mostly focus on high Nb addition, which inevitably bring in an increasing of density. In this study, a carbon fibers coated with graphene reinforced TiAl alloy composite was fabricated by powder metallurgy, melt spun and vacuum melting. This composite got remarkable mechanical properties combined with a prominent density reduction. In contrast with pure TiAl ingots, this sample exhibits an average fracture strain from 16% up to 26...
February 5, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29390756/assessing-the-shielding-of-engine-noise-by-the-wings-for-current-aircraft-using-model-predictions-and-measurements
#5
Ana Vieira, Mirjam Snellen, Dick G Simons
Reducing aircraft noise is a major issue to be dealt with by the aerospace industry. In addition to lowering noise emissions from the engine and airframe, also the shielding of engine noise by the aircraft is considered as a promising means for reducing the perceived noise on the ground. In literature, noise shielding predictions indicate significant reductions in received noise levels for blended wing body configurations, but also for conventional aircraft with the engines placed above the wings. Little work has been done in assessing these potential shielding effects for full aircraft under real operational conditions...
January 2018: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/29386715/aeromedical-solutions-for-aerospace-safety
#6
Pawan Kapoor, Deepak Gaur
All facets of activity in the speciality of Aviation Medicine are essentially aimed at enhancing aerospace safety. This paper highlights some innovative changes brought about by Aerospace Medicine in the three major fields of the speciality namely, medical evaluation, aeromedical training and research. Based on lab and field studies, military aircrew are now permitted flying with Modifinil as 'Go' Pill and Zolpidem as 'No-Go' Pill during sustained operations. Several other drugs for disabilities like Hypertension and CAD are now permitted for aviators...
October 2017: Medical Journal, Armed Forces India
https://www.readbyqxmd.com/read/29384132/integrated-nanomaterials-for-extreme-thermal-management-a-perspective-for-aerospace-applications
#7
Michael Thomas Barako, Vincent Gambin, Jesse Tice
Nanomaterials will play a disruptive role in next-generation thermal management for high power electronics in aerospace platforms. These high power and high frequency devices have been experiencing a paradigm shift toward designs that favor extreme integration and compaction. The reduction in form factor amplifies the intensity of the thermal loads and imposes extreme requirements on the thermal management architecture for reliable operation. In this perspective, we introduce the opportunities and challenges enabled by rationally integrating nanomaterials along the entire thermal resistance chain, beginning at the high heat flux source up to the system-level heat rejection...
January 31, 2018: Nanotechnology
https://www.readbyqxmd.com/read/29369940/a-case-study-of-the-ncrp-156-wound-model-of-embedded-du-using-data-from-urine-uranium-concentrations-of-wounded-veterans
#8
Michael T Walkingstick, Eric S Krage, Richard R Brey
Depleted uranium (DU) munitions were initially used by the United States (U.S.) military during the first Persian Gulf War in 1991 in order to penetrate heavily armored vehicles. However, as a result of friendly fire, several U.S. military personnel received intakes from DU munitions. One of the ongoing concerns for these wounded veterans is the potential long-term exposure received from DU embedded fragments. The United States Army Institute of Public Health (AIPH) is the first laboratory that analyzes the urine bioassays from Army Soldiers that are injured with DU fragments...
March 2018: Health Physics
https://www.readbyqxmd.com/read/29362394/improvement-in-creep-life-of-a-nickel-based-single-crystal-superalloy-via-composition-homogeneity-on-the-multiscales-by-magnetic-field-assisted-directional-solidification
#9
Weili Ren, Chunlin Niu, Biao Ding, Yunbo Zhong, Jianbo Yu, Zhongming Ren, Wenqing Liu, Liangpu Ren, Peter K Liaw
The improvement of the creep properties of single-crystal superalloys is always strongly motivated by the vast growing demand from the aviation, aerospace, and gas engine. In this study, a static magnetic-field-assisted solidification process significantly improves the creep life of single-crystal superalloys. The mechanism originates from an increase in the composition homogeneity on the multiscales, which further decreases the lattice misfit of γ/γ' phases and affects the phase precipitation. The phase-precipitation change is reflected as the decrease in the γ' size and the contents of carbides and γ/γ' eutectic, which can be further verified by the variation of the cracks number and raft thickness near the fracture surface...
January 23, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29351240/machine-learning-and-infrared-thermography-for-fiber-orientation-assessment-on-randomly-oriented-strands-parts
#10
Henrique Fernandes, Hai Zhang, Alisson Figueiredo, Fernando Malheiros, Luis Henrique Ignacio, Stefano Sfarra, Clemente Ibarra-Castanedo, Gilmar Guimaraes, Xavier Maldague
The use of fiber reinforced materials such as randomly-oriented strands has grown in recent years, especially for manufacturing of aerospace composite structures. This growth is mainly due to their advantageous properties: they are lighter and more resistant to corrosion when compared to metals and are more easily shaped than continuous fiber composites. The resistance and stiffness of these materials are directly related to their fiber orientation. Thus, efficient approaches to assess their fiber orientation are in demand...
January 19, 2018: Sensors
https://www.readbyqxmd.com/read/29337858/investigation-on-the-effect-of-a-pre-center-drill-hole-and-tool-material-on-thrust-force-surface-roughness-and-cylindricity-in-the-drilling-of-al7075
#11
Amir Hossein Ghasemi, Amir Mahyar Khorasani, Ian Gibson
Drilling is one of the most useful metal cutting processes and is used in various applications, such as aerospace, electronics, and automotive. In traditional drilling methods, the thrust force, torque, tolerance, and tribology (surface roughness) are related to the cutting condition and tool geometry. In this paper, the effects of a pre-center drill hole, tool material, and drilling strategy (including continuous and non-continuous feed) on thrust force, surface roughness, and dimensional accuracy (cylindricity) have been investigated...
January 16, 2018: Materials
https://www.readbyqxmd.com/read/29325340/-association-between-small-dense-low-density-lipoprotein-cholesterol-and-carotid-atherosclerosis
#12
X F Li, X Xu, G W Liang, D H Shao
Objective: To explore the association between small dense low-density lipoprotein cholesterol (sdLDL-C) and carotid atherosclerosis. Methods: 1 578 subjects were enrolled in an annual health check-up program in aerospace center hospital from 2016 to 2017, and these patients were divided into 471 cases (men 343 and women 128) with carotid atherosclerosis (subjects with increased carotid artery intima-media thickness or carotid atherosclerosis plaque) and 1 107 cases (men 567 and women 540) with non- carotid atherosclerosis according to ultrasonography...
December 26, 2017: Zhonghua Yi Xue za Zhi [Chinese medical journal]
https://www.readbyqxmd.com/read/29305694/pervasiveness-of-uvc254-resistant-geobacillus-strains-in-extreme-environments
#13
Courtney Carlson, Nitin K Singh, Mohit Bibra, Rajesh K Sani, Kasthuri Venkateswaran
We have characterized a broad collection of extremophilic bacterial isolates from a deep subsurface mine, compost dumping sites, and several hot spring ecosystems. Spore-forming strains isolated from these environments comprised both obligate thermophiles/thermotolerant species (growing at > 55 °C; 240 strains) and mesophiles (growing at 15 to 40 °C; 12 strains). An overwhelming abundance of Geobacillus (81.3%) and Bacillus (18.3%) species was observed among the tested isolates. 16S rRNA sequence analysis documented the presence of 24 species among these isolates, but the 16S rRNA gene was shown to possess insufficient resolution to reliably discern Geobacillus phylogeny...
January 5, 2018: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/29286629/environmentally-benign-production-of-stretchable-and-robust-superhydrophobic-silicone-monoliths
#14
Alexander Davis, Salvatore Surdo, Gianvito Caputo, Ilker S Bayer, Athanassia Athanassiou
Superhydrophobic materials hold an enormous potential in sectors as important as aerospace, food industries or biomedicine. Despite this great promise, the lack of environmentally friendly production methods and limited robustness remain the two most pertinent barriers to the scalability, large-area production and widespread use of superhydrophobic materials. In this work, highly robust superhydrophobic silicone monoliths are produced through a scalable and environmentally friendly emulsion technique. It is first found that stable and surfactantless water-in-polydimethylsiloxane (PDMS) emulsions can be formed through mechanical mixing...
December 29, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29251571/shape-memory-alloy-based-soft-gripper-with-variable-stiffness-for-compliant-and-effective-grasping
#15
Wei Wang, Sung-Hoon Ahn
Soft pneumatic actuators and motor-based mechanisms being concomitant with the cumbersome appendages have many challenges to making the independent robotic system with compact and lightweight configuration. Meanwhile, shape memory actuators have shown a promising alternative solution in many engineering applications ranging from artificial muscle to aerospace industry. However, one of the main limitations of such systems is their inherent softness resulting in a small actuation force, which prevents them from more effective applications...
December 2017: Soft Robotics
https://www.readbyqxmd.com/read/29247359/preparation-and-thermoelectric-characteristics-of-ito-ptrh-ptrh-thin-film-thermocouple
#16
Xiaohui Zhao, Hongmin Wang, Zixiang Zhao, Wanli Zhang, Hongchuan Jiang
Thin film thermocouples (TFTCs) can provide more precise in situ temperature measurement for aerospace propulsion systems without disturbance of gas flow and surface temperature distribution of the hot components. ITO/PtRh:PtRh TFTC with multilayer structure was deposited on alumina ceramic substrate by magnetron sputtering. After annealing, the TFTC was statically calibrated for multiple cycles with temperature up to 1000 °C. The TFTC with excellent stability and repeatability was realized for the negligible variation of EMF in different calibration cycles...
December 15, 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/29240721/extreme-environment-sensing-using-femtosecond-laser-inscribed-fiber-bragg-gratings
#17
REVIEW
Stephen J Mihailov, Dan Grobnic, Cyril Hnatovsky, Robert B Walker, Ping Lu, David Coulas, Huimin Ding
The femtosecond laser-induced fiber Bragg grating is an effective sensor technology that can be deployed in harsh environments. Depending on the optical fiber chosen and the inscription parameters that are used, devices suitable for high temperature, pressure, ionizing radiation and strain sensor applications are possible. Such devices are appropriate for aerospace or energy production applications where there is a need for components, instrumentation and controls that can function in harsh environments. This paper will present a review of some of the more recent developments in this field...
December 14, 2017: Sensors
https://www.readbyqxmd.com/read/29233251/this-month-in-aerospace-medicine-history
#18
(no author information available yet)
No abstract text is available yet for this article.
January 1, 2018: Aerospace Medicine and Human Performance
https://www.readbyqxmd.com/read/29233248/results-of-amhp-journal-survey-on-open-access
#19
Pamela C Day
Day PC. Results of AMHP journal survey on Open Access. Aerospace Med Hum Perform. 2018; 89(1):70-71.
January 1, 2018: Aerospace Medicine and Human Performance
https://www.readbyqxmd.com/read/29231868/a-data-driven-response-virtual-sensor-technique-with-partial-vibration-measurements-using-convolutional-neural-network
#20
Shan-Bin Sun, Yuan-Yuan He, Si-Da Zhou, Zhen-Jiang Yue
Measurement of dynamic responses plays an important role in structural health monitoring, damage detection and other fields of research. However, in aerospace engineering, the physical sensors are limited in the operational conditions of spacecraft, due to the severe environment in outer space. This paper proposes a virtual sensor model with partial vibration measurements using a convolutional neural network. The transmissibility function is employed as prior knowledge. A four-layer neural network with two convolutional layers, one fully connected layer, and an output layer is proposed as the predicting model...
December 12, 2017: Sensors
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