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本文主要在探討平面幾何學中的兩個重要結果—三角形中的『Menelaus定理』與『Ceva定理』推廣到任意的『球面n邊形』的相對應結果,對於任意的球面n邊形,我們分別找到了『球面n邊形的Menelaus共線定理』與『球面n邊形的Ceva共點定理』的一般化結果。
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利用海冰體積與北極震盪指數預測聖嬰現象發生之可能性
本研究利用海冰覆蓋面積的變化、北極震盪指數(Arctic Oscillation index, AOI)和南方震盪指數(Southern Oscillation index, SOI)的相關性,希望可以探討與聖嬰現象的關聯。 取用1950年到2020年的海冰覆蓋面積資料及195!年到2020年的SOI及AOI資料。我們將AOI和SOI做折線圖、X-Y圖,數據分成平常年、聖嬰前、聖嬰時、聖嬰後、反聖嬰前、反聖嬰時、反聖嬰後,試圖找出一些規則。利用區間分析來觀察區間範圍大小及上下界的數值隨不同事件發生的次序,探討各個事件的特徵。 聖嬰年時,區間縮小,反聖嬰年則區間略為放大且數值上升。最後將1997年聖嬰年的數據和區間做疊圖,並以2018年底到2020年的聖嬰轉反聖嬰來做驗證。若AOI的區間縮小、或海冰覆蓋面積下降後上升,表示可能是聖嬰現象要來的前兆。此外,本研究也發現,無法單獨區隔聖嬰年和反聖嬰年,兩者間會相互影響,應該要把聖嬰跟反聖嬰合併為一個氣候變化週期,才能做準確的預測。
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Maximum Isosceles Sets
An isosceles set is a collection of points in which any subset of three points forms an isosceles triangle. We want to find the upper bound for the size of isosceles sets in any n-dimensional Euclidean space. Kido has already completed the study of isosceles sets in 3 and 4-dimensional space. We study the upper bound of spherical two-distance sets, a special type of isosceles sets, to help us find the upper bound of isosceles sets. More specifically, Musin’s Linear Programming technique on spherical two-distance sets could be used to study isosceles sets if a consistent relationship between isosceles sets and two-distance sets can be characterized. We offer a conjecture of this relationship. We also offer non-trivial lower bounds of isosceles sets in dimension 5 with 17 points and dimension 7 with 30 points as examples.
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激增殺手T細胞的水膠細胞平台於免疫療法的應用
本實驗研發新型水膠細胞優化技術,成功提供一個平台供應淋巴細胞激活信號(MHC-antigen complex)、共刺激配體及細胞因子刺激三大要素,能激增殺手T細胞。實驗中優化的水膠細胞能完整保留細胞膜的表面特性,經實驗證實無生物安全性的疑慮。另外本實驗也著重於探討人工合成抗原細胞強韌度對T細胞增生程度的影響。我們利用水膠細胞易改變細胞質強韌度且不影響生物相容性的優點,針對T細胞增生程度進行比較。本研究結果顯示,高細胞質強韌度(120kPa)的人工合成抗原細胞(aAPCs, Artificial antigen presenting cells)擁有高效率的T細胞激活潛力,相對於低細胞質強韌度(25kPa)的對照組可以提高約51.2%,並達到顯著差異,推測其和收縮性及突出性絲狀肌動蛋白增加以致訊號增強有關。本實驗的新型水膠細胞優化技術提供臨床醫學免疫療法一個高潛力的新技術平台。
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What is the relationship between angular velocity and power efficiency of a twin blanded single rotor helicopter system, in hover?
A traditional helicopter requires 60 - 80% more power to hover than when in forward or lateral flight, making the manoeuvre extremely power inefficient. To maximise efficiency, industrially many properties of the helicopter and rotor have been changed and tested, for example: optimising blade shape, fuselage shape and changing weights of different helicopter components. This report in particular aims to find a relationship between power efficiency and angular velocity for a twin bladed hovering helicopter with a single rotor. The angular velocity of a blade measures the frequency of its revolution about a fixed point. A theoretical approach was first taken and then justified with empirical data. Firstly, a model for power efficiency was derived with William Froude’s momentum and blade element theory. The efficiency equations incorporated the thrust and power coefficients. Therefore, the research focused on determining values for these coefficients by manipulating equations, using industrial specifications and simulations from the XFOIL software. In order to validate the accuracy for such theoretically generated data, an experiment was conducted for a comparison. The theoretical and empirical data were concurrent, as they followed a similar trend and the empirical values overlapped within the theoretical error bars. The power efficiency for different angular velocities were then found by substituting values for the coefficients. The results demonstrated a positive relationship; where, as angular velocity increases, power efficiency increases too, then plateaus and repeats the same trend once again. The research raises many questions and could be extended by determining if a similar relationship exists for tri-copters and quadcopters.
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The influence of lanscape on nest preferences and behavior of twig nesting Hymenoptera
The occurrence and behavior of insects is significantly affected by the environment they live in. In this thesis, I dealt with the influence of structure of landscape on nesting preferences of Hymenoptera. For this comparison I had chosen to work with twig-nesting Hymenoptera, for which I have placed artificial nest opportunities into four biotopes – heath, edge of a heath, country lanes between fields and field. The studied location is located south of Znojmo near Podyjí national park. Particularly, I have focused on small carpenter bees of genus Ceratina. My results show that there is a big difference in the species distribution between the habitates of field and heath. The habitats of edge of a heath and country lanes make up a gradient between these two biotopes. The ecosystem of fields was preferred by a sphecid wasp Pemphredon lethifer and Ceratina cyanea. On the other hand, the ecosystem of heath was preferred by Ceratina chalybea, Ceratina nigrolabiata and megachille bee Hoplitis tridentata. I had also found out that in species that are more abundant on heaths, there is higher mortality of offsprings. Heaths were a place of the highest competition between species, as a result of which species with a lower body weight (Ceratina nigrolabiata) have been pushed into narrower twigs by larger species (Ceratina chalybea). I recorded a high number of nests in biparental bee Ceratina nigrolabiata, which were guarded only by mother in fields and country lane habitats. This may indicate that Ceratina nigrolabiata is only facultatively biparental, not strictly biparental as was considered until now.
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PVA unveiled the actual role of starch in the Briggs-Rauscher reaction
The Briggs Rauscher reaction (BR reaction) is one of the famous oscillating reactions; the aqueous mixture of KIO3, H2SO4, H2O2, C3H4O4, MnSO4, and starch exhibit color change between yellow and blue-purple repeatedly. The blue-purple color formation is due to the iodine test reaction caused by inclusions of polyiodides such as I3- and I5- in the helical structure of starch. Therefore, starch has been regarded as only an indicator in the BR reaction. But our seniors have found that the oscillation did not last without starch. They hypothesized that starch’s linear helical framework is necessary to elongate the lifetime of the oscillating reaction. If this hypothesis is correct, similar BR-type oscillations must be observed when other polymers with helical structures are used instead of starch. We found the literature which reports that polyvinyl alcohol (PVA) forms a helical structure and indicates the iodine test reaction. In our research, we studied the BR reactions using PVA, with different saponification degrees and viscosities. First, we studied the correlation between the structural features of PVA and the iodine color reaction by spectroscopic approach, exhibiting that PVA with low saponification form helical structures and show the iodine color reactions, which gives red color solutions. Second, we found that additions of the helical-structured PVA to the reaction solution instead of starch induces the BR-type oscillating reactions, while PVA without helical structure induces only a few numbers of oscillations. This is the world-first example of the oscillating reaction using PVA. The oscillation that lasted for 6 minutes with 23 oscillations was almost the same as that of the general BR reaction using starch. We concluded that the polymers with helical structures are intrinsic to elongate the lifetime of the BR reaction. Furthermore, we found that the addition of K3[Fe(CN)6], which has a high redox activity, in the reaction solution with PVA drastically elongated the lifetime (50 min) and increased the numbers of the oscillations (nearly 100 times). This result suggests that the oxidation-reduction reactions by the ferricyanide ion promotes the redox process of iodine and iodide ions.
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An Easy Method to Discuss Properties of Simplified Solid-state Tesla Coil
Wireless transmission products are widely used in our daily life. In this research, we focus on knowing how solid-state tesla coil works in different conditions and finding the best parameters through an easy way. In our work, a commercial electroscope was used as detector for measuring the strength of radio wave created by our simplified tesla coils. In fact, many factors would lead to experimental erorrs such as detectors, selected types of NPN BJT components, applied voltage and measuring position of height. Therefore, all of the factors were under control to make sure of accuracy and precision for our designed measuring method. In our experiment, graphics of radio wave distribution around tesla coils were drew by mathemetic software of GeoGebra. It shows the BJT types of 2n2222 had good performance for wireless transmisstion efficiency. To our surprised, we found the extended wires (called antenna) from the top of tesla coil also had an ability to transfer electromagnetic energy, and had good retention if the extended wires were within the length of main coil’s height. Finally, the shape’s and size’s effect was determined by our testing work. The result shows that pipe’s length, pipe’s diameter and turns ratio of two coils had great influence on tesla coil’s transmission efficiency. It was found that the tesla’s performance would be more efficient if wire was used to make the length twice rather than make the diameter twice. However, the turns ratio of secondary coil to primary coil would change while making the length twice. To avoid that, we fixed the length and decrease the turns of primary coil. At last, we found tesla coil must work at the turns of primary coil higher than two. Furthermore, the frequency of radio wave not only had less relationship with their length or diameter but also had less relationship with types of BJT In our study, our handmade tesla coil was succesfully applied for wireless charging and we find that the induced voltage decrease in propotion to cube root of distance between tesla coil and induced coil.
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Modification of silica surface with supercritical water as a tool indicating new possibilities of existing separation methods
Silica capillaries have been an integral part of the instrumentation used in many areas of analytical chemistry for decades, especially in analytical separations. In most cases, they are used without treatment, occasionally forceless chemical surface treatments are made to suppress or enhance the activity of silanol groups. The aim of this work was to disrupt the inner surface of the capillary, perfectly smooth from manufactory, so that relatively coarse and various structures would be created, and to study their influence on the separation efficiency. The uniqueness of the used solution is based on the use of special properties of water exposed to high temperatures and pressures (supercritical water), which is able to disrupt this chemically inert material because of its aggressivity. In total, over 2000 experiments were carried out in order to define conditions suitable for the formation of various types of surface structures. Due to the high amount of resulting data, our own database application was created, allowing not only to save the picture of the structure and experimental conditions information, but also to clearly sort them out and create image reports according to the specified parameters. Samples representing individual types of structures were then selected from this database and a number of silica capillaries with a configuration suitable for electromigration analyzes were prepared. The creation of a structured surface in the input part of the separation capillary enabled the separation of some classes of substances and biosamples, which cannot be analyzed on standard capillaries with a smooth surface. An example is the complete separation of two strains of Staphyllococcus aureus bacteria (MRSA and MSSA), or the use of the absorbing capabilities of a structured surface to study the interactions of these bacteria with bacteriophages. This ability was also used in the determination of Aspergillus fungus in a sample taken directly from the patient's lungs, where there was achieved a significant increase in the sensitivity of the analysis. Structured capillaries can also be used in the analysis of food samples, i.e., for the separation of β-lactoglobulins A and B in cow's milk, which belong to its main allergens.
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An Analysis and Optimization of Double Parallelogram Lifting Mechanism
Double Parallelogram Lifting Mechanism (DPLM) is a compact and stable lifting mechanism with a large extension range widely adopted in robot designs. Rubber bands and springs are often installed on the DPLM to lighten the motors' load and maintain its height, yet the installation positions are often obtained through trial and error. This project aims at finding the optimal rubber band installation positions for DPLM using modeling and optimization techniques. A mathematical model which describes the forces and moments acting on all the linkages of DPLM was derived based on the conditions for the static equilibrium and verified with a 3D simulation software. A genetic algorithm (GA) was implemented to optimize rubber band installation positions, which managed to find solutions with the overall root-mean-square- error (RMSE) of the net moment less than 2 for 2 to 6 rubber bands. A further statistical analysis of 50000 random rubber band samples showed that installing rubber bands in triangles is the best solution with the overall lowest RMSE. A test was conducted with a prototype of the DPLM and the results were consistent with our model and optimization. This project derived and verified a mathematical model for the DPLM, and found the optimal way and positions to install rubber bands. The results of this project provides a theoretical basis for controlling DPLM with rubber bands, allowing it to be further adopted in industrial robots that require repetitive lifting and lowering such as inspection robots and aerial work platforms.
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星狀網路點擴展運算漢米爾頓容錯性質研究
本作品研究星狀網路和完全網路,兩種不同結構的連結網路,使用點擴展運算結合成一個網路結構,並且在一定的容錯範圍內,保證存在漢米爾頓迴圈性質。漢米爾頓迴圈在連結網路的研究中相當重要,若存在此性質,則可以保證發送訊號時,能將訊號發送給連結網路上的每一個元件並接收,且不會重覆接收到訊號。我們使用圖形理論的方式,將星狀網路和完全網路,這兩種連結網路結構,分別抽象化成星狀圖和完全圖,網路中的元件抽象化為點,元件之間的連線,抽象化成邊。如果元件之間的連線故障,無法使用,則稱為壞邊。我們證明 n+1 維度星狀圖和 n 維度完全圖使用點擴展運算後,壞邊數量最多是 n-4 時,保證存在漢米爾頓迴圈。
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Enhancement of Online Stochastic Gradient Descent using Backward Queried Images
Stochastic gradient descent (SGD) is one of the preferred online optimization algorithms. However, one of its major drawbacks is its predisposition to forgetting previous data when optimizing through a data stream, also known as catastrophic interference. In this project, we attempt to mitigate this drawback by proposing a new low-cost approach which incorporates backward queried images with SGD during online training. Under this new approach, we propose that for every new training sample through the data stream, the neural network is optimized using the corresponding backward queried image from the initial dataset. After compiling the accuracy of the proposed method and SGD under a data-stream of 50,000 training cases with 10,000 test cases and comparing our algorithm to SGD, we see substantial improvements in the performance of the neural network with two different MNIST datasets (Fashion and Kuzushiji), classifying the MNIST datasets at a high accuracy for the mean, minimum, lower quartile, median, and upper quartile, while maintaining lower standard deviation in performance, demonstrating that our proposed algorithm can be a potential alternative to online SGD.
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