學術演講


2018/12/26(三)13:00綜合大樓1樓48111B教室演講 : 張滋芳 特任助理教授(日本名古屋大學宇宙地球環境研究所)

張貼者:2018年12月20日 下午6:11Dabby Lu   [ Ann-Chen Jang 已於 2018年12月21日 上午12:52 更新 ]

講題:From investigation of magnetospheric substorms to development of space weather research
摘要:THEMIS satellites clustered at substorm orbit together with optical observations from the ground or space make it possible for us to investigate substorm events practically. New constraints on substorm onset phenomena have been firmly built after the launch of THEMIS project. The clearest constraint comes from activations of azimuthally-spaced auroral forms manifested before breakup initiation. Pi2 disturbances are identified from the ground and space prior to substorm onsets and throughout substorm events. On the other hand, substorms inject energetic particles to inner magnetosphere which may become an important source of particles with relativistic energies. ERG satellite observes the entire radiation belts and provides critical data for developing models which give variations of radiation belts and inner magnetosphere. The enhancement in electron fluxes during substorms can be a few orders larger than the pre-onset conditions. Thus substorm-associated fields must be taken into consideration regarding modeling of radiation belt electron populations. We build a substorm injection model and successfully produce the main features of flux evolution captured in multi-satellite observations. Radiation belts models or global magnetosphere models which consider variations at whole MLT and L-shells can include fields of substorms by coupling our model and thus provide more refined results closer to realities to explore local particle accelerations up to relativistic energies, or to even further develop the feasible capabilities related to space weather forecast. In the end of this talk, I will also introduce my future research plans and directions.

<專題討論>2018/12/20(四)14:10綜合大樓2樓48218教室演講 : 張博宇 助理教授(成功大學電漿所)

張貼者:2018年12月16日 下午6:38Dabby Lu

講題: Exploring space science, generating coherent x rays and neutrons via developing a metallic ion thruster and a pulsed-power system
摘要:Two independent projects are being conducted in Pulsed-Power Generator for Space Science (PGS) laboratory to study space science, generating coherent x rays and neutrons. One is to build a metallic ion thruster using magnetron e-beam bombardments. The other one is to build a pulsed-power system. For the metallic ion thruster, the principle of e-beam evaporations is used to generate ions. Ions are first generated from a metallic target being evaporated and ionized by thermal emission electrons and are accelerated by electric fields to provide the thrust. Different from inert gas used in conventional plasma thrusters, the metal target is in the solid state, high density, easy to be stored and cheap. A mass flow rate of 8.0 ± 1.3 µg/sec using Zn was measured. Therefore, let the parameter β be the ionization rate of the metal vapor, the estimated thrust is β mN with a power of 630 W assuming 5 kV accelerating voltage is used. The thrust is much larger than those provided from existing thrusters with similar powers to date. For the pulsed-power system, 6 kJ of energy is first stored in twenty 1 µF capacitors charged to 50 kV and is discharged to a load in a short period of time to provide high-power output. The preliminary data analysis of discharge test of two capacitors charged to 20 kV showed that a peak current of 30 kA was delivered. The extrapolated peak current of final design from this test is 500 kA with a rise time of 1 µs giving an output power of 10 GW. The system will be used to generate (1) plasma jets for studying space sciences specifically on interactions between solar winds and unmagnetized planets using conical wire arrays; (2) soft x-ray laser using capillary z-pinch; and (3) neutrons using dense plasma focus. Status of developments for both projects and proposed research topics will be introduced.

2018/12/18(二)13:00綜合大樓1樓48111B教室演講 : 林忠義 博士(中央大學天文研究所)

張貼者:2018年12月11日 下午9:29Dabby Lu

講題:The study of comets from ground-based observations to space missions
摘要:With almost a century of experience and several decade observations using ground‐based and space telescopes monitoring in a wavelength band from the cm‐wave radio astronomy to x‐ray, we are confident that we were able to use such data effectively for studying the most of physical properties and chemical abundance of cometary nuclei. However, the chemical composition of cometary nuclei could be different from comet to comet. For instance, SPCs (short period comets) have been subjected more times to solar radiation than LPCs (long period comets), and they should show a lower content of volatile material and a more highly processed surface. In addition, the investigation of the chemical composition is indirect because it considers only molecules that are released from the nucleus surface that can be affected by numerous processes, for instance cosmic ray. Therefore, how the molecular composition and abundance of the coma is related to the one inside the nucleus is still an open issue. 
In this talk, I will present recent study of comets from the ground-based observations to space mission and show how important to link ROSETTA’s incredible detail results to ground‐based observations. The link and direct comparison between 67P and other comets observed in the same ways from Earth will be discussed. Furthermore, I will discuss the interaction between cometary plasma tail and solar wind using our observing data set.

2018/12/11(二)13:00綜合大樓1樓48111B教室演講 : 饒駿頌 博士(Astroparticle Physics Theory Group, DESY)

張貼者:2018年12月4日 下午7:47Dabby Lu

講題:The study of streaming instability in space, astrophysical, and laboratory plasmas
摘要:With important applications to space, astrophysical, and laboratory environments, plasma wave excitation led by the drift energy of streaming particles (streaming instability) is an extensively studied phenomenon in plasma physics.  In the Sun-Earth environment, for instance, the electrostatic streaming instability is generally considered to lie in the origin of the observed electrostatic solitary waves and in the core mechanism of type III solar radio bursts.  As in astrophysical environments, a non-resonant type electromagnetic streaming instability is also proposed as a candidate for the amplification of interstellar magnetic fields in the upstream region of supernova remnant shocks, which plays an important role in the efficiency of cosmic-ray particle acceleration.

In this talk I will present my past studies of streaming instability problems from linear theory and numerical simulation, to the application to laboratory astrophysics experiments. The research topics include the formation of phase-space electron-hole structure in the electron-positron plasma, fire-hose-type electromagnetic streaming instabilities, and cosmic-rays driven magnetic field amplification.  Together with these ongoing projects, I will also discuss potential future approaches within this rich research field.

<專題討論>2018/12/6(四)14:10綜合大樓2樓48218教室演講 : 張晃崇 博士(台灣優貝克科技)

張貼者:2018年11月29日 下午6:50Dabby Lu   [ 已更新 2018年12月4日 下午6:19 ]

講題:如何策略規劃理工科生畢業後生涯發展–人生不應該是一條不歸路

<專題討論>2018/11/29(四)14:10綜合大樓2樓48218教室演講 : Prof. Satoshi Hamaguchi(Center for Atomic and Molecular Technologies, Graduate School of Engineering, Osaka University, Osaka, Japan)

張貼者:2018年11月22日 下午6:08Dabby Lu

講題:Introduction to Plasma-based Atomic-Layer Processes for Modern Semiconductor Device Fabrication
摘要:As the sizes of semiconductor devices continue to diminish and are now approaching atomic scales, the downsizing of transistors following Moore’s law is bound to end in the near future. However, the continuing market demand for higher performance and lower energy consumption of large-scale integrated (LSI) circuits has driven invention of new device technologies such as three-dimensional (3D) device structures and devices based on non-silicon materials. Manufacturing of these non-conventional devices also poses new challenges for processing technologies. One of the latest processing technologies that are considered crucial in modern semiconductor technologies is Atomic-Layer Processes (ALPs), which typically refers to Atomic Layer Deposition (ALD) and Atomic Layer Etching (ALE). In these processes, deposition or etching processes take place layer by layer in atomic sclae. For example, in plasma-based ALE of SiO2 films, deposition of a few-angstrom deep fluorocarbon (FC) layer on a SiO2 film and a subsequent application of low-energy Ar+ ions to the fluorocarbon-deposited SiO2 film causes sub-mono-layer etching of the SiO2 surface. By repeating these steps, a layer-by-layer etching of SiO2 can be achieved selectively over other materials such as Si. Despite their low throughput, ALPs are now widely welcomed in industry as they typically allow highly uniform processes over a large area with atomic-scale accuracy. In this lecture, after a brief introduction of plasma processing in general, basics of ALPs will be discussed and latest research results for experimental and computational studies on ALE processes will be presented.

<專題討論>2018/11/22(四)14:10綜合大樓2樓48218教室演講 : 河森榮一郎 教授(成功大學電漿所)

張貼者:2018年11月18日 下午5:31Dabby Lu

講題:Entropy of Waves
摘要:While entropy is elusive, it is an indispensable physical quantity for identifying direction of evolution of thermodynamic many-body systems, measuring decoherence of quantum systems, evaluating the amount of information loss, and so on. Originally it was introduced in order to describe irreversibility of equilibrium thermodynamic systems. The idea of entropy has been expanded into various fields such as quantum computing, information science, evaluation of networks and so on as well as to nonequilibrium systems. In this talk, we consider entropy of classical wave turbulence systems. 
The concept of wave turbulence, that describes nonlinearly interacting waves, covers areas of fluid turbulence, optical turbulence, plasma turbulence, and so on. In the field of wave turbulence, wave action, which represents the number of waves as a function of a quantum number such as frequency or wave number, has been a subject of investigation. I propose a new idea representing wave field entropy, that doesn’t require conventional random-phase approximation (RPA). The idea is application of the concept of the von Neumann entropy to classical wave turbulence systems and it is a natural extension of Gibbs entropy (equivalently Shannon entropy in information science). For that purpose, a concept of a density matrix of classical wave fields is introduced together. I show validity of the classical von Neumann entropy to distinguish turbulent states and coherent state having broad spectrum quantitively. Examples, to which my idea is fit, include supercontinuum, optical turbulence, rogue waves, drift wave turbulence and so on, that are recognized as wave turbulence.

<專題討論>2018/11/15(四)14:10綜合大樓2樓48218教室演講 : 李芳承 博士(國家實驗研究院台灣海洋科技研究中心)

張貼者:2018年11月10日 下午5:24Dabby Lu

講題 : 前進水波槽實驗分析與模擬應用
摘要 : 1.利用雷射光學量測配合高速攝影技術系統拍攝一系列前進波影像,再利用影像處理技巧進行邊緣偵測,數位化、分析波浪連續自由液面高程。其中從全尺度拍攝中,成功地利用 LabVIEW 發展多斷面影像連結技術與邊緣偵測技術,藉由量測 Y 軸向的放大影像觀察所波浪通過結構物理特徵現象。數位化水面高程資料,再透過Matlab發展二維快速傅立葉轉換(2DFFT) 結合一維 Morlet 小波轉換(1DMWT)方法完整分解波浪訊號技術。
2.發展運算模擬平台,以無網格(SPH)數值模式探討水波槽問題(多相流)。

<專題討論>2018/11/8(四)14:10綜合大樓2樓48218教室演講 : 江致宇 博士候選人(成功大學電漿所)

張貼者:2018年11月2日 上午1:10Dabby Lu   [ Ann-Chen Jang 已於 2018年11月13日 下午6:57 更新 ]

講題:Big Data in Space Sciences
摘要:經過數十年來的探索,太空已不再是人類遙不可及的夢想之地,過去利用衛星觀測所累積的各種科學及工程的數據,不但掀開太空中神祕的面紗,一項項待解的太空科學議題也一一獲得驗證,人類對太空的認識已不再是之前瞎子摸象的時代,新的衛星任務目標都更加具體,然而接下來可能會有人想問,什麼是太空探索的下一步呢? 大家或許有注意到,這幾年全球掀起了太空熱,各種創新衛星、載具研發或甚至加值服務都不斷出籠,這一切的推手都可歸功於太空產業走向商業化的成果,而有了這樣好的立基點之後,加快了衛星研發的時程和發射升空的頻率,同時數據資料的累積也預期將以驚人的速度成長。因此,面對太空大數據時代的來臨,我們做好準備了嗎? 從過去到現在所留下的龐大數據資料,是否能進行更有效率的大數據應用與開發,為未來太空AI時代打下基礎呢? 本演講將以太空科學資料(電漿相關)的角度切入,進行介紹與分析,希望聽眾能對太空資料處理流程能有更進一步的認識。

<專題討論>2018/11/1(四)14:10綜合大樓2樓48218教室演講 : 詹寶珠 特聘教授(成功大學電機系)

張貼者:2018年10月28日 下午11:36Dabby Lu

講題:An Introduction to Deep Learning Network Models and their Applications
摘要:Deep learning neural networks have been the main focus in recent researches and applications. In this talk, we will give an introduction of the concept of neural networks and the deep learning models. A brief overview of the development of deep learning network models for image analysis and other applications will be provided. Some mechanisms in achieving successful training will also be discussed.

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