On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

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The Observation of Gravitational Waves from a Binary Black Hole Merger

Microfabricated integrated circuits revolutionized computation by vastly reducing the space, labor, and time required for calculations. Microfluidic systems hold similar promise for the large-scale automation of chemistry and biology, suggesting the possibility of numerous experiments performed rapidly and in parallel, while consuming little reagent. While it is too early to tell whether such a vision will be realized, significant progress has been achieved, and various applications of significant scientific and practical interest have been developed. Here a review of the physics of small volumes (nanoliters) of fluids is presented, as parametrized by a series of dimensionless numbers expressing the relative importance of various physical phenomena. Specifically, this review explores the Reynolds number Re, addressing inertial effects; the Peclet number Pe, which concerns convective and diffusive transport; the capillary number Ca expressing the importance of interfacial tension; the Deborah, Weissenberg, and elasticity numbers De, Wi, and El, describing elastic effects due to deformable microstructural elements like polymers; the Grashof and Rayleigh numbers Gr and Ra, describing density-driven flows; and the Knudsen number, describing the importance of noncontinuum molecular effects. Furthermore, the long-range nature of viscous flows and the small device dimensions inherent in microfluidics mean that the influence of boundaries is typically significant. A variety of strategies have been developed to manipulate fluids by exploiting boundary effects; among these are electrokinetic effects, acoustic streaming, and fluid-structure interactions. The goal is to describe the physics behind the rich variety of fluid phenomena occurring on the nanoliter scale using simple scaling arguments, with the hopes of developing an intuitive sense for this occasionally counterintuitive world.

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Microfluidics: Fluid physics at the nanoliter scale

I. the origin of species by means of natural selection

The boundary layer equations for plane, incompressible, and steady flow are 

$$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Boundary Layer Theory

We survey progress over the past 25 years in the development of microscale devices for pumping fluids. We attempt to provide both a reference for micropump researchers and a resource for those outside the field who wish to identify the best micropump for a particular application. Reciprocating displacement micropumps have been the subject of extensive research in both academia and the private sector and have been produced with a wide range of actuators, valve configurations and materials. Aperiodic displacement micropumps based on mechanisms such as localized phase change have been shown to be suitable for specialized applications. Electroosmotic micropumps exhibit favorable scaling and are promising for a variety of applications requiring high flow rates and pressures. Dynamic micropumps based on electrohydrodynamic and magnetohydrodynamic effects have also been developed. Much progress has been made, but with micropumps suitable for important applications still not available, this remains a fertile area for future research.

https://microfluidics.stanford.edu/Publications/Micropumps_Cooling/Laser%20Review%20of%20Micropumps%20in%20JMM.pdf

A review of micropumps

Energy efficiency of direct contact membrane distillation

Delta wings in steady flow can provide high lift at large angles of attack and are therefore used on many highperformance aircrafts. However, the unsteady aerodynamic properties of a delta wing are practically unknown, although vital for operating and designing airplanes for poststall and other maneuvering. In this study, the flowfields around two pitching delta wings with apex angles of 90 and 60 deg were visualized in a towing tank at chord Reynolds numbers up to 3.5 xlO. The reduced frequency was varied in the range 0.05-3. The leadingedge separation vortex went through a growth-decay cycle with hysteresis during a pitching period. A distinct change of the separated flow was observed at a reduced frequency around ir.

The pitching delta wing

Introduction Mohamed Gad-el-Hak Scaling of Micromechanical Devices William Trimmer and Robert H Stroud Mechanical Properties of MEMS Materials William N Sharpe, Jr Flow Physics Mohamed Gad-el-Hak Integrated Simulation for MEMS: Coupling Flow-Structure-Thermal-Electrical Domains Robert M Kirby, George Em Karniadakis, Oleg Mikulchenko, and Kartikeya Mayaram Molecular-Based Microfluidic Simulation Models Ali Beskok Hydrodynamics of Small-Scale Internal Gaseous Flows Nicolas G Hadjiconstantinou Burnett Simulations of Flows in Microdevices Ramesh K Agarwal and Keon-Young Yun Lattice Boltzmann Simulations of Slip Flows in Microchannels Ramesh K Agarwal Liquid Flow in Microchannels Kendra V Sharp, Ronald J Adrian, Juan G Santiago, and Joshua I Molho Lubrication in MEMS Kenneth Breuer Physics of Thin Liquid Films Alexander Oron Bubble/Drop Transport in Microchannels Hsueh-Chia Chang Fundamentals of Control Theory J William Goodwine Model-Based Flow Control for Distributed Architectures Thomas R Bewley Soft Computing in Control Mihir Sen and Bill Goodwine Index

MEMS : Introduction and Fundamentals

L'ecoulement est perturbe par injection ou aspiration d'un fluide secondaire par une fente le long du bord d'attaque d'une aile delta. Essais en tunnel hydrodynamique et en soufflerie. Etude par visualisations et mesures de vitesse des effets de la perturbation sur le champ d'ecoulement. Calcul de diverses quantites statistiques du champ de vitesse aleatoire

Control of the discrete vortices from a delta wing

Micro-air-vehicles (MAV) are small, autonomous, aerial vehicles designed for reconnaissance and difficult to reach missions. Microelectromechanical systems (MEMS) are extremely small machines in which electronic and mechanical components are combined on a single silicon chip using photolithographic micromachining techniques. The question of whether MEMS can help improve the performance of futuristic MAV is pondered. The treatment focuses on the lifting and control surfaces of MAV, particularly the fixed-wing type. Two additional ideas are advanced to improve the performance of the lifting surfaces of MAV: effecting chaotic mixing to energize the laminar boundary layer and thus delay separation; and using genetic algorithms to optimize the shape of the airfoil section

Mohamed Gad-el-Hak

Papers

Energy efficiency of direct contact membrane distillation

The pitching delta wing

MEMS : Introduction and Fundamentals

Control of the discrete vortices from a delta wing

Micro-Air-Vehicles: Can They be Controlled Better?