Masters of Science / Upcoming and ongoing 21cm surveys, such as the Square Kilometre Array (SKA), Hydrogen Epoch of Reionization Array (HERA) and Low Frequency Array (LOFAR), will enable imaging of the neutral hydrogen distribution on cosmological scales in the early Universe. These experiments are expected to generate huge imaging datasets that will encode more information than the power spectrum. This provides an alternative unique way to constrain the astrophysical and cosmological parameters, which might break the degeneracies in the power spectral analysis. The global history of reionization remains fairly unconstrained. In this thesis, we explore the viability of directly using the 21cm images to reconstruct and constrain the reionization history. Using Convolutional Neural Networks (CNN), we create a fast estimator of the global ionization fraction from the 21cm images as produced by our Large Semi-numerical Simulation (SimFast21). Our estimator is able to efficiently recover the ionization fraction (xHII) at several redshifts, z = 7; 8; 9; 10 with an accuracy of 99% as quantified by the coefficient of determination R2 without being given any additional information about the 21cm maps. This approach, contrary to estimations based on the power spectrum, is model independent. When adding the thermal noise and instrumental effects from these 21cm arrays, the results are sensitive to the foreground removal level, affecting the recovery of high neutral fractions. We also observe similar trend when combining all redshifts but with an improved accuracy. Our analysis can be easily extended to place additional constraints on other astrophysical parameters such as the photon escape fraction. This work represents a step forward to extract the astrophysical and cosmological information from upcoming 21cm surveys.

The key requirements of a reliable neural signal recording system include low power to support long-term monitoring, low noise, minimum tissue damage, and wireless transmission. The neural spikes are also detected and sorted on-chip/off-chip to implement closed-loop neuromodulation in a high channel count setup. All these features together constitute an empirical neural recording system for neuroscience research. In this prospectus, we propose to develop a neural signal acquisition system with wireless transmission and feature extraction. We start by designing a prototype entirely built with commercial-off-the-shelf components, which includes recording and wireless transmission of synthetic neural data and feature extraction. We then conduct the CMOS implementation of the low-power multi-channel neural signal recording read-out circuit, which enables the in-vivo recording with a small form factor. Another direction of this thesis is to design a self-powered motion tracking read-out circuit for wearable sensors. As the wearable industry continues to advance, the need for self-powered medical devices is growing significantly. In this line of research, we propose a self-powered motion sensor based on reverse electrowetting-on-dielectric (REWOD) with low-power integrated electronics for remotely monitoring health conditions. We design the low-power read-out circuit for a wide range of input charges, which is generated from the REWOD sensor.

Among various energy harvesting technologies reverse electrowetting-on-dielectric energy harvesting (REWOD) has been proved to harvest energy from low frequency motion such as many human motion activities (e.g. walking, running, jogging etc.). Voltage rectification and DC-DC boosting of low magnitude AC voltage from REWOD can be used to reliably self-power the wearable sensors. In this work, a commercial component-based rectifier and DC-DC converter is designed and experimentally verified, for further miniaturization standard 180 nm CMOS process is used to design the rectifier and the DC-DC boost converter.This work also includes the MATLAB based model for REWOD energy harvester for various REWOD models. In REWOD energy harvesting, a mechanical input during the motion causes the electrolyte placed in between two dissimilar electrodes to squeeze back and forth thereby periodically changing the effective interfacial area, hence generating alternating current. The alternating current is given to the rectifier design. There is no realistic model that has been developed yet for this technique. Thereby, a MATLAB based REWOD model is developed for the realistic simulation of the REWOD phenomenon. In the work, a comparison of different REWOD models such as planar surface, rough surface and porous models are performed demonstrating the variations in capacitance, current and voltage.

京都大学 / 新制・課程博士 / 博士(エネルギー科学) / 甲第23537号 / エネ博第428号 / 新制||エネ||82(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授 岸本 泰明, 教授 中村 祐司, 教授 田中 仁 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

Composite cascode stages have been used in operational amplifier designs to achieve ultra-high gain at very low power. The flexibility and simplicity of the stage makes it an appealing choice for low power op-amp designs. Op-amp design using the composite cascode stage is often made more difficult through the lack of a design process. A design process to aid in the selection of the MOSFET dimensions is provided in this thesis. This process includes a table-based method for selection of the widths and lengths of the MOSFETs used in the composite cascode stage. Equations are also derived for the gain, bandwidth, and noise of the composite cascode stage with each of the devices operating in the various regions of inversion.

No description available.

京都大学 / 新制・課程博士 / 博士(医学) / 甲第23772号 / 医博第4818号 / 新制||医||1056(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 村川 泰裕, 教授 松田 文彦, 教授 篠原 隆司 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

In the world today, Concert Halls for Symphony Orchestra and Choir are generally â enclosed performance spacesâ that are completely cut-off from the outside: Whether itâ s a time of daylight or moonlight, rain or shine, summer or winter, spring or autumn, the environment within remains the same all the time. I asked the question: â What if a concert hall offers views outside?â To be more specific, the question is: â What if a concert hall offers views outside through the use of glass, along with other building materials, despite the fact that glass offers lower reflectivity and lower transmission loss for lower frequencies of sound, compared to certain other materials?â Hence the title: Interaction of Low Frequency Sound with Glass and other Building Materials in the Design of a Concert Hall for Symphony Orchestra and Choir. / Master of Architecture

Astrophysical phenomena such as self-annihilation of primordial black holes (PBHs), gamma ray bursts (GRBs), and supernovae are expected to produce single dispersed pulses detectable in the low end of the radio spectrum. Analysis of these pulses could provide valuable information about the sources, and the surrounding and intervening medium. The Eight-meter-wavelength Transient Array (ETA) is a radio telescope dedicated to the search for these pulses in an 18 MHz bandwidth centered at 38 MHz. ETA consists of 10 dual-polarized active dipoles providing an all-sky field of view. This thesis describes the results of a search campaign using ETA, namely, a Crab giant pulse (CGP) search. CGPs are already known to exist, and thus provide an excellent diagnostic for system performance. We found 11 CGP candidates in 14 hours of data. Although there has not been a single compelling detection (signal-to-noise ratio > 6), our analysis shows that at least a few of these candidates may be CGPs. We also explain the analysis preparation for PBH and GRB searches. Additionally, we describe the instrument and a software "toolchain" developed for the analysis of data that includes calibration, radio frequency interference (RFI) mitigation, and incoherent dedispersion. A dispersed pulse simulation code was developed and used to test the toolchain. Finally, improvements are suggested. / Master of Science

This report presents the design of a conceptual prototype aimed at identifying keys in specific positions inside a cabinet utilizing Radio-frequency identification (RFID)technology. The prototype integrates RFID readers, managed by a microcontroller unit(MCU), establishing a backend peripheral system. The cabinet is made of steel, and given RFID’s sensitivity to nearby metal, experimentation was conducted to evaluate the impact of metal proximity on the reading range. Experimental results reveal a reduction in the reading range of 15 mm (43%) by one metal sheet and 26 mm (74%) by two metal sheets present, highlighting the relation between RFID technology and metallic environments. Additionally, the finished prototype is also presented in the Results and Discussion section, giving a more detailed insight into its practical implementation. This project demonstrates the viability of item-level identification through the utilization of low-frequency readers. Particularly relevant for positional identification, the short reading range of a low-frequency reader offers precision by limiting the area in which a detected transponder may be located. / Denna rapport presenterar designen av en konceptuell prototyp avsedd att identifiera nycklar på specifika positioner i ett skåp med användning av Radio-frequency identification (RFID) teknologi. Prototypen integrerar RFID läsare, hanterade av en microcontroller unit (MCU), och etablerar ett perifert backendsystem. Skåpet är gjort av stål, och givet RFIDs känslighet mot nära metal har experiment utförts för att utvärdera hur metallen påverkar en läsares omfång. Experimentella resultat avslöjar en reduktion i läsarens omfång på 15 mm (43%) med en metallplatta och 26 mm (74%) med tvåmetallplattor närvarande. Dessutom presenteras den färdiga prototypen i Resultat och Diskussionsdelen, för att ge en mer detaljerad insyn på dess praktiska implementation. Detta projektet demonstrerar genomförbarheten av identifikation på artikelnivå genomanvändandet av lågfrekvens läsare. Särskilt relevant för positionell identifikation är det korta omfånget av en lågfrekvens läsare, då detta erbjuder precision genom att begränsaområdet där en transponder kan lokaliseras.