다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

비만아 부모의 돌봄 경험: q 방법론

A review of shape memory alloy research, applications and opportunities

Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made with regard to the development of electrospinning methods and engineering of electrospun nanofibers to suit or enable various applications. We aim to provide a comprehensive overview of electrospinning, including the principle, methods, materials, and applications. We begin with a brief introduction to the early history of electrospinning, followed by discussion of its principle and typical apparatus. We then discuss its renaissance over the past two decades as a powerful technology for the production of nanofibers with diversified compositions, structures, and properties. Afterward, we discuss the applications of electrospun nanofibers, including their use as "smart" mats, filtration membranes, catalytic supports, energy harvesting/conversion/storage components, and photonic and electronic devices, as well as biomedical scaffolds. We highlight the most relevant and recent advances related to the applications of electrospun nanofibers by focusing on the most representative examples. We also offer perspectives on the challenges, opportunities, and new directions for future development. At the end, we discuss approaches to the scale-up production of electrospun nanofibers and briefly discuss various types of commercial products based on electrospun nanofibers that have found widespread use in our everyday life.

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

In our work, we investigate systematically the deformation and instability of a rotating cylinder of compressible material under fixed end thrust using Neo-Hookean material model. We employ numerical methods to study the solution of the second order differential equation for the radial deformation, which represents the deformation of the cylinder under loading conditions. We further analyse the instability behaviour of the rotating elastic cylinder using the incremental deformation theory and obtain the critical value of angular velocity when buckling occurs. Finally, we plot a phase diagram, which illustrates the regions of stable, buckling and no solution with respect to angular velocity and end thrust. • We developed theoretical model of a rotating cylinder under end thrust, adopted numerical methods to investigate its deformation and instability behaviour, and obtained a phase diagram which depicts the regions of “stable”, “buckling”, and “no solution” with respect to angular velocity and end thrust. 

Finite deformation and instability of a rotating cylinder under end thrust

Flight vehicles are often designed to function around a primary operating point such as an efficient cruise or a high
maneuverability mode. Performance and efficiency deteriorate rapidly as the airplane moves towards other portions of
the flight envelope. One solution to this quandary is to radically change the shape of the aircraft. This yields both
improved efficiency and a larger flight envelope. This global shape change is an example of morphing aircraft . One
concept of morphing is the span morphing wing in which the wingspan is varied to accommodate multiple flight
regimes. This type of design allows for at least two discreet modes of the aircraft. The original configuration, in which
the extensible portion of the wing is fully retracted, yields a high speed dash mode. Fully extending the wing provides
the aircraft with a low speed mode tailored for fine tracking and loiter tasks.
This paper discusses the design of a span morphing wing that permits a change in the aspect ratio while simultaneously
supporting structural wing loads. The wing cross section is maintained by NACA 4412 rib sections . The span morphing
wing was investigated in different configurations. The wing area and the aspect ratio of the span morphing wing increase
as the wings pan increases. Computational aerodynamics are used to estimate the performance and dynamic
characteristics of each wing shape of this span morphing wing as its wingspan is changed. Results show that in order to
obtain the same lift, the conventional wing requires a larger angle of attach(AOA) than that of the span morphing
wing.The lift of the span morphing wing increases as the wing span ,Mach number and AOA increases.

Yanju Liu

Papers

Finite deformation and instability of a rotating cylinder under end thrust

Design and aerodynamic characteristics of a span morphing wing