Transport phenomena in the brain: from hydrocephalus to dementia
周鼎贏 博士 (Dept. of Engineering Science & Institute of Biomedical)
<專題討論>2017/3/16(四)14:10綜合大樓2樓48218教室演講
Cerebral tissue and related transport phenomena in the brain combine a number of characteristics that make their theoretical and computational representation and analysis particularly challenging: the brain has extreme metabolic and oxygenation needs but with minimal capacity to store glucose and oxygen, it is perfused by a markedly complex vascular system, it produces and floats in cerebrospinal fluid which is in continuous exchange with vascular plasma and – enclosed in the cranium – is probably the most inaccessible organ in the human body.
We propose a novel multiscale approach for addressing these modelling challenges that involve the representation of cerebral tissue as a porous elastic medium permeated by a multiplicity of passages – each with its own features (for instance, porosity and permeability) These networks have the potential to communicate with each other, according to predefined transport laws. We apply this new modelling framework to the case of Hydrocephalus – a disease that is equally important and paradoxical. Hydrocephalus can be succinctly described as the abnormal accumulation (imbalance between production and circulation) of cerebrospinal fluid within the brain. Using HCP as a test bed, one is able to account for the necessary mechanisms involved in the interaction between cerebral fluid production, transport and drainage. The model is discretised in a variety of formats, through the established finite difference method, finite difference – finite volume coupling and also the finite element method. Both chronic and acute hydrocephalus was investigated in a variety of settings, and accompanied by emerging surgical techniques where appropriate.
Dr Dean Chou was very recently awarded his D.Phil. degree from the University of Oxford (2011-2017). His research topic focuses on multi-scale cerebral mechanics. He received his first MSc. degree at the Department of Engineering Science and Ocean Engineering at the National Taiwan University (2002-2005). His second MSc. degree was awarded from the Department of Chemical and Material Engineering from the University of Alabama in Huntsville (2009-2010), where he received funding by CFD-ACE+ to aid the development of its macro-particle module. He is involved in the VPH-DARE@IT project since 2013.
| 附件: 20170316 周鼎贏博士.pdf
The secrets of Stradivari violins
戴桓青 助理教授 ( 臺灣大學化學系)
<專題討論>2017/3/2(四)14:10綜合大樓2樓48218教室演講
The modern violin was invented nearly 500 years ago, but the most famous violins all came from a small town in Italy called Cremona. There were two famous makers in Cremona, Antonio Stradivari (1644-1737) and Giuseppe Guarneri “del Gesu” (1698-1744), who made amazing instruments that all top violinists wanted to play. For the past 200 years, no maker has been able to recreate the magic of Stradivari and Guarneri violins.
In collaboration with Chimei Museum in Tainan, we have investigated the acoustics and wood properties of Stradivari violins. By recording various violins in the Chimei collection, we found that Stradivari violins produced formants (resonance peaks) differently compared to other violins. We also found that the maple wood used by Stradivari had been treated with minerals. After 300 years of aging, the hemicellulose in the wood has undergone natural hydrolysis. The effect of high frequency vibrations has further altered the ultrastructure of wood in Stradivari violin but not his cellos. We believe that the unique properties of wood may contribute to the unique sound of Stradivari violins.
| 附件: 20170302 戴桓青助理教授.pdf
Plasma Applications to Energy and Environmental Fields
西田靖 教授 ( 龍華科技大學 )
<演講公告>2016/12/8(四)11:00綜合大樓1樓48111B教室演講
In this talk, plasma applications to (1) high energy particle acceleration and (2) hydrogen source will be introduced. For particle acceleration, plasma waves are excited for accelerating particles. Because the electric field strength of plasma waves will be about 1000 times stronger than that in the large accelerator such as “LHC” (Large Hadron Collider) located in CERN, Switzerland, which has about 37 km circumference in order to push up the electron collision energy to 8 TeV, the plasma wave accelerator will be 1/1000 of LHC in size. For plasma wave accelerators the wave-guide for microwave transmission line is a key acceleration tool and the maximum electric field strength inside the cavity can reach 100 MV/m. For the hydrogen source, which can be used for fuel cells to produce electricity (to learn more about electricity and electric power, visit "Throw The Switch" on the Smithsonian website Powering a Generation of Change.), it is usually produced by chemical processes in large plants. However, such processes produce large amount of dirty gases and have storage and distribution problems. To produce hydrogen cleanly, we have developed the plasma discharge technology to directly decompose hydrocarbon fuels to hydrogen gas and carbon particles. The experimental results of decomposition of hydrocarbon gases into hydrogen gas and carbon particles using plasma discharge technology will be presented.
Local and global observations of Richtmeyer-Meskov instability in laser produced plasmas
藏滿康浩 副教授 ( 中央大學物理系)
<專題討論>2016/12/1(四)14:10綜合大樓2樓48218教室演講
We experimentally investigate the Richtmeyer-Meskov instability (RMI) in laser-produced inhomogeneous plasmas. When a shock wave interacts with an interface of inhomogeneous plasma, the RMI is excited due to the shear along the contact surface. We observed the spatial and temporal evolutions of the global plasma structures with optical imaging, showing the transition from the typical mushroom like structure to turbulence. We also observed the local plasma quantities with corrective Thomson scattering (CTS) measurement. The spatial resolved CTS data show the several transitions from blue to red shifts at different positions, indicating vortex. We estimated the time scale of the RMI growth using the observed data. The estimated time scale is about 1 ns, which is much shorter than our experimental time scale of ~ 10 ns, and thus, there is enough time for RMI to grow.
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