40,687 research outputs found
Wireless Intraocular Pressure Sensing Using Microfabricated Minimally Invasive Flexible-Coiled LC Sensor Implant
This paper presents an implant-based wireless pressure
sensing paradigm for long-range continuous intraocular
pressure (IOP) monitoring of glaucoma patients. An implantable
parylene-based pressure sensor has been developed, featuring an
electrical LC-tank resonant circuit for passive wireless sensing
without power consumption on the implanted site. The sensor
is microfabricated with the use of parylene C (poly-chlorop-
xylylene) to create a flexible coil substrate that can be folded
for smaller physical form factor so as to achieve minimally invasive
implantation, while stretched back without damage for
enhanced inductive sensor–reader coil coupling so as to achieve
strong sensing signal. A data-processed external readout method
has also been developed to support pressure measurements. By
incorporating the LC sensor and the readout method, wireless
pressure sensing with 1-mmHg resolution in longer than 2-cm distance
is successfully demonstrated. Other than extensive on-bench
characterization, device testing through six-month chronic in vivo
and acute ex vivo animal studies has verified the feasibility and
efficacy of the sensor implant in the surgical aspect, including
robust fixation and long-term biocompatibility in the intraocular
environment. With meeting specifications of practical wireless
pressure sensing and further reader development, this sensing
methodology is promising for continuous, convenient, direct, and
faithful IOP monitoring
A new photobioreactor for continuous microalgal production in hatcheries based on external-loop airlift and swirling flow
This study deals with the scale of a new photobioreactor for continuous microalgal production
in hatcheries. The combination of the state-of-art with the constraints inherent to hatcheries
has turned the design into a closed, artificially illuminated and external-loop airlift
configuration based on a succession of elementary modules, each one being composed of two
transparent vertical interconnected columns. The liquid circulation is ensured pneumatically
(air injections) with respect to a swirling motion (tangential inlets). A single module of the
whole photobioreactor was built-up to investigate how parameters, such as air sparger type,
gas flow rate, tangential inlet, column radius and height can influence radiative transfer,
hydrodynamics, mass transfer and biological performances. The volumetric productivities
were predicted by modeling radiative transfer and growth of Isochrysis affinis galbana (clone
Tahiti). The hydrodynamics of the liquid phase was modeled in terms of global flow behavior
(circulation and mixing times, PĂ©clet number) and of swirling motion decay along the column
(Particle Image Velocimetry). The aeration performances were determined by overall
volumetric mass transfer measurements. Continuous cultures of Isochrysis affinis galbana
(clone Tahiti) were run in two geometrical configurations, generating either an axial or a
swirling flow. Lastly, the definitive options of design are presented as well as a 120 Liter
prototype, currently implemented in a French mollusk hatchery and commercialized
Comparison of Geometric Optimization Methods with Multiobjective Genetic Algorithms for Solving Integrated Optimal Design Problems
In this paper, system design methodologies for optimizing heterogenous power devices in electrical engineering are investigated. The concept of Integrated Optimal Design (IOD) is presented and a simplified but typical example is given. It consists in finding Pareto-optimal configurations for the motor drive of an electric vehicle. For that purpose, a geometric optimization method (i.e the Hooke and Jeeves minimization procedure) associated with an objective weighting sum and a Multiobjective Genetic Algorithm (i.e. the NSGA-II) are compared. Several performance issues are discussed such as the accuracy in the determination of Pareto-optimal configurations and the capability to well spread these solutions in the objective space
A Multiscale Thermo-Fluid Computational Model for a Two-Phase Cooling System
In this paper, we describe a mathematical model and a numerical simulation
method for the condenser component of a novel two-phase thermosyphon cooling
system for power electronics applications. The condenser consists of a set of
roll-bonded vertically mounted fins among which air flows by either natural or
forced convection. In order to deepen the understanding of the mechanisms that
determine the performance of the condenser and to facilitate the further
optimization of its industrial design, a multiscale approach is developed to
reduce as much as possible the complexity of the simulation code while
maintaining reasonable predictive accuracy. To this end, heat diffusion in the
fins and its convective transport in air are modeled as 2D processes while the
flow of the two-phase coolant within the fins is modeled as a 1D network of
pipes. For the numerical solution of the resulting equations, a Dual
Mixed-Finite Volume scheme with Exponential Fitting stabilization is used for
2D heat diffusion and convection while a Primal Mixed Finite Element
discretization method with upwind stabilization is used for the 1D coolant
flow. The mathematical model and the numerical method are validated through
extensive simulations of realistic device structures which prove to be in
excellent agreement with available experimental data
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