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以具適應性種子偵測法進行無序列比對之三代定序錯誤校正;Alignment-Free Error Correction for Third-Generation Sequencing by Adaptive Seed Identification
No full text[[abstract]]因為第三代定序技術所產生的序列為較長的序列、定序的偏差較低與定序分布平均等特性，使得第三代定序技術成為現有基因組裝(de novo assembly)的熱門選項。但是由於它產出的序列錯誤率較高，所以在進行基因組裝前必須進行序列的錯誤修正。目前錯誤修正的方法可分為比列序列分析法，如Canu，和非比對列序分析法；兩者面臨著準確度與速度之間的妥協。我們在之前研發出了一個利用FM-Index的非比對錯誤修正法，稱為FILEC，但是在中至大物種的組裝完整度上仍不讓人滿意。在這篇論文裡，我們提出了新的方法來提高FILEC在高相似度區域的種子準確率。方法首先會把高相似度與低相似度的區域區分開來，並且動態的使用不同的策略找種子；接下來錯誤的種子會被修剪與移除。實驗結果顯示出我們的方法相較於Canu不僅比較快，也保證了組裝的完整度與正確性。雖然在大物種組裝會變的破碎，速度上仍然比Canu快。
The thrid-generation sequencing technology is now commonly used for de novo assembly projects because of longer reads, less sequencing bias, and more uniform coverage. However, it comes at the cost of higher error rate, which requires error correction prior to assembly. The correction algorithms are divided into alignment-based methods like Canu, and alignment-free methods, which face the tradeoff between accuracy and speed. We previously developed an alignment-free algorithm based on FM-index, named FILEC, but the assembly contiguity is unsatisfactory in moderate and large genomes. In this thesis, we propose a new method to improve seeding accuracy of FILEC in repeat regions. The proposed method distinguishes unique and repetitive regions and adaptively uses different seeding strategies. The remaining error seeds were trimmed until the errors were removed. The experiment results showed that our method runs much faster than Canu and guarantees the contiguity and concordance of assembly . In large genome dataset, although the assembly result becomes fragmented, our method is still faster than Canu
機率主成份分析用於預測學生成績表現之研究;Study of Probabilistic Principal Component Analysis for Student Academic Performance Prediction
No full text音圈馬達之手機相機光學變焦模組設計;
No full text[[abstract]]輕便又多功能的智慧型手機近年改變了人類的生活習慣，諸多功能的智慧型手機同時亦取代多樣電子產品，數位相機便是其中之一。隨著手機相機模組技術不斷的進步，已逐漸取代數位相機，相較於傳統相機的三大功能：自動對焦、光學防手震以及光學變焦，手機相機的模組已具備有自動對焦，光學防手震也越趨成熟，然而在變焦方面，受到智慧型手機的外型體積等許多條件限制，發展變得困難，因此多採用數位變焦的方式，然而若要達到影像的放大縮小而不失真，則需要光學變焦。 目前市面上少數幾款具有光學變焦效果的智慧型手機，搭配的微致動器較多採用步進馬達，ASUS近期推出具備三倍光學變焦的手機相機，搭配的是HOYA公司的CUBE模組備受關注，因此本論文將透過逆向工程研究搭載在其智慧型手機上的相機模組，以利了解手機相機模組之特性與規格，並且搭配閱讀其他文獻與專利後，提出一款使用音圈馬達驅動的光學變焦模組。而本論文利用稜鏡的反射改變光行徑的路線，藉此在有限的空間中達到拉長行程的效果，並且搭配閉迴路的控制，分別控制兩側的音圈馬達，達到變焦的效果。而在模擬與完整模組之設計後，本論文透過製作金屬雛形品進行實驗，以驗證搭配音圈馬達之手機相機模組的性能。亦將實驗結果與模擬進行比較，以證明長行程光學變焦特徵之音圈馬達手機相機模組設計能與模擬匹配，並且符合市售產品要求。
In recent years lightweight and multifunction smartphones have changed the way that people live. It also replaced multi-electronic products, and digital camera is one of them. As cell phone camera module technology has been improved continuously, the digital camera has been gradually replaced by the cell phone. Comparing to the three major functions of the traditional camera: auto-focus (AF), optical image stabilization (OIS) and optical zoom, mobile phone camera module has been equipped maturely in terms of AF and OIS. However, in the aspect of optical zoom, restricted by the appearance and volume of smart phones or any other conditions, the development of optical zoom becomes more difficult so that most of the cell phones equipped with digital zooming. To achieve the image zooming without distortion, technology of optical zoom is needed.Currently there are few smartphones with optical zoom which are driven by stepper motors in the market. Recently, ASUS presented a novel smartphone ASUS Zoom ZX551ML, which equipped with triple optical zoom by HOYA's CUBE module catches more consumers’ attention. According to the observation, this thesis aims to get more information and specification through the reverse engineering of this camera module. In order to propose a novel optical zoom module driven by voice coil motors, further studying relative references and patents was needed. To achieve the effect of elongated stroke in a limited space, the new camera module used prism reflection to change the path of light and drive two voice coil motors on both sides with closed-loop control. After designing the complete module, this thesis evaluated its performance using a laboratory-built prototype which is matched to the simulation. The simulation and experimental results showed that the proposed camera module is satisfied with the requirements of the commercial products
滾珠螺桿受傳動齒輪嚙合影響下之動態響應;Dynamic Response of a Ball Screw under the Engagement Effect of Transmission Gear Pair
No full text[[abstract]]本文主要探討滾珠螺桿受齒輪傳動對影響下之動態特性。簡單來說，當滾珠螺桿開始運轉時，由馬達軸齒輪將動力傳遞給滾珠螺桿軸齒輪，傳遞過程因齒輪背隙或加工誤差而造成嚙合振動，使滾珠螺桿產生非線性動態響應。滾珠螺桿利用Solidwork軟體建立3D模型，並匯入ABUQUS軟體求解出不同預壓條件下之扭矩值，利用Matlab將作用於齒輪對上的扭矩值計算出時變嚙合剛性，再將嚙合剛性匯進一維滾珠螺桿模型內進行動態特性計算。模型之時變嚙合剛性利用齒形撓度公式計算，旋轉桿件運動形狀則使用大域模態法(GAMM)模擬，利用拉格朗日法推導出系統運動方程式後，使用朗吉-庫塔法找來出具齒輪對滾珠螺桿之動態響應。時變嚙合剛性大多文獻研究利用弦波或方波來進行模擬，但實際嚙合過程為單齒與雙齒交替進行，所以嚙合剛性並非為常數或弦波變化。因此，本文利用齒形撓度公式計算出之時變嚙合剛性來探討具齒輪對滾珠螺桿系統之動態特性。時變嚙合剛性除齒牙本體變形效益外，還需考慮齒牙底部圓角彈性變形及齒輪圓盤彈性變形之影響。由計算結果得知，時變嚙合剛性比沒有考慮齒輪圓盤及圓角彈性變形約降低20%。另外，利用由跑合實驗驗證之模擬模型計算出之不同預壓條件扭矩值，推算出之時變嚙合剛性並帶入一維系統模型內進行計算，結果可以看出具時變嚙合剛性影響之滾珠螺桿系統動態出現拍頻現象，與實驗中之調頻及連續頻譜現象吻合，且滾珠螺桿之動態行為明顯產生非週期性運動(aperiodic motion)。
The dynamic characteristics of a ball screw system equipped with gear pair are discussed in this dissertation. Briefly, the power is created by motor on the drive pinion and transmitted to the driven gear on ball screw. Serious vibration is caused by backlash and manufacture error of gear in the transmission process. These errors will results in the nonlinear dynamic characteristics of ball screw at the engagement situation.3D ball screw model is established by Solidwork, and the torque is calculated for the various preload conditions by ABAQUS. The gear mesh stiffness is calculated by using the above torque value, and is inserted into the 1-D ball screw model to simulate the dynamic response of the geared ball screw system by MATLAB. The time-varying gear mesh stiffness is calculated by the compliance of gear tooth, and the mode shape of shaft is simulated by GAMM. The equation of motion of the geared ball screw system is derived by Lagange’s equation, and then the Range-Kutta method is employed to obtain the dynamic characteristics of geared ball screw.The results show that the time-varying gear mesh stiffness is not only dominated by the deformation of gear body, but also influenced by the elastic effect of fillet and foundation of tooth. According to the results, the time-varying gear mesh stiffness considering the elastic effect of fillet and foundation is 20% lower than that without the above effect. The torque of ball screw is obtained by the experimental apparatus in the run-in condition with the various preload conditions, and then is estimated the various gear mesh stiffness. The dynamic characteristics of beating phenomenon is appeared at the geared ball screw with the time-varying gear mesh stiffness effect in the simulation, It has the same relationship from the experimental results in which the modulation and continuous frequency spectrum appear. Above all, the aperiodic motion appear obviously in the dynamic behavior of geared ball system which is still dominated by the time-varying mesh effect of gear engagement
植晶過程中細長型晶元強度測試與膠材特性參數開發;Strength Test of Slender Die and Development of Glue Characteristic Parameters in Die Pick Up Process
No full text[[abstract]]平面顯示器技術不斷進步，元件尺度設計邁向輕薄短小已經變成一種趨勢。常用之驅動 IC；晶粒軟板式封裝(Chip On Film Packaging, COF)；的製程技術也朝高功能、高功率以及高 I/O 數邁進。COF 因受限於擺放空間需設計成高細長比晶片，與傳統晶片相比，更易在植晶頂針過程中造成晶粒斷裂損傷。因此探討細長型晶元的強度與植晶過程的參數是改善植晶損傷的重要研發方向。 本研究使用四點彎矩實驗(Four Point Bending, 4PB)，以測試出晶粒斷裂力的極限值且利用高速攝影技術拍攝實驗瞬間，並得知較厚的晶圓在實驗中並不會產生滑移之現象。在數值分析方面，建立 4PB 有限元素分析模型，模擬實驗過程進而得到細長型晶元之破裂應力。膠材測試部分，利用微拉力試驗機建立正向拉伸測試(Normal Test)和剪向拉伸測驗(Shear Test)，得到之後模擬所需之膠合元素參數範圍，最後使用田口法在範圍中選取參數數值，再搭配植晶實驗和高速攝影及模擬，逆尋膠合元素之材料參數。
According to the enhancement of LCD technique, the requirements of lighter, thinner, shorter, and smaller products have become a trend for the LCD industry. The typical driver IC, Chip On Film Packaging (COF), has to improve the design to meet the target of high performance with high I/O count. Compared with the traditional package, the die in COF needs to be designed as a slender shape with high slenderness ratio. It can be easily caused damage by the adhesive force between bonding UV type and die during die pick up process. Therefore, to investigate breaking strength of high slenderness ratio die, and analyze the die bond pick up parameters are very important research topics. In this research, we use Four Point Bending (4PB) test to measure the limited breaking force of slender shape die and use the technology of high speed camera to capture whole experimental process clearly, and satisfy the thickness die will not slip during the 4PB test. Moreover, finite element simulation model about 4PB was developed to obtain the breaking stresses for slender shape die as the design limit for pick up process. About adhesive test, the normal test and shear test will be setup to find the cohesive element parameter range, at last, use Tauguchi method to choose the value from the parameter range, use the die pick up experiment with high speed camera and simulation to find the correct cohesive parameter
多軸加工機組裝誤差量測與補償方法;
No full text[[abstract]]多軸加工機是目前正在急速發展的工具機種，在組裝後的多軸加工機，由於旋轉軸的中心軸線難以量測，旋轉後產生的運動誤差更是難以檢測與校正。本論文提供一個模擬多軸工具機的動靜態誤差方法，以座標轉換矩陣方法，由基座出發視為固定端，依照機台各軸堆疊方式同時設定各軸動件的動作與所走的加工路徑之誤差，每個軸皆以總行程定義其路徑的誤差軌跡；在旋轉軸方面則設定其各方向的靜動態偏擺誤差。將機台路徑誤差以多項式方式定義，含常數項表示為靜態誤差，總共建立108個誤差係數，分別代表各軸進給時在六個自由度方向的動、靜態路徑誤差。模擬本文中座標轉換矩陣與誤差多項式使用探頭量測與循圓量測器去量測旋轉軸上的靜態誤差與動態誤差在量測件的變化與循圓量測器桿長變化。本論文為了解決旋轉軸誤差，最後以旋轉軸各項誤差與運動的方式，來設定24項誤差參數，直接算得靜態誤差與運動誤差，以驗證數據處理的理論與可行性，模擬結果證實能確實計算出各項設定的誤差項。
The 5-axis CNC machine is widely used in the metal-cutting of workpiece with complex geometry. However, the manufacturing and assembly errors of the rotating axes of the 5-axis machine are difficult to be measured and compensated by CNC software later on. In this thesis, a methodology for estimating the assembly and kinematic errors for the rotating axes in the B-C configuration. The assembly and kinematic error of the 3 linear axes (X, Y, Z) of 5-axis CNC machine are assumed to be measured by the Laser linear measuring instrument and perfectly corrected by the homogenous coordinate transformation matrix in the CNC controller and the assembly and kinematic error of linear axes are neglected in this study. In this thesis, we develop a methodology combining the double-ball bar and the coordinate measuring on certain standard parts to estimate the assembly and kinematic errors of the B-C rotary table. Based on the estimated assembly and kinematic errors, homogeneous coordinate transformation matrix from machine base to the workpiece are derived and verified in the numerical examples. There are at least 24 assembly and kinematic errors for the B-C rotary table and each error is represented as a polynomial function. With specified double-ball bar setups and motion paths, totally 108 coefficients of error polynomials are approximately fitted by the least-square-error method. Several numerical examples are presented to verify the validation of the proposed methodology for estimating and compensating the assembly and manufacturing errors of the B-C rotary table
深度神經網路應用於雙軸平台之熱誤差估測;
No full text[[abstract]]工具機在進行加工時常會因為機件之間的高速磨擦而升溫產生熱變形，降低加工精度，因此若能預先知道加工時所產生熱變形，就能對工具機做有效的補償。本研究基於雙軸平台上應用了類神經網路與深度學習技術透過雙軸平台上幾個固定的監測值預測出在加工期間滾珠導螺桿的熱變形情況。本研究使用了倒傳遞網路(BPN)與遞迴神經網路中的長短期記憶模型(LSTM)，運用了七種不同加工情況之數據對網路進行訓練與測試，其中包含了三種單一加工情況與四種複合加工情況。網路之輸入數據以實驗所量測得之馬達端溫度、支撐端溫度、室溫、螺帽溫度、室溫、螺帽速度、螺帽位置以及平台所走過的距離等七個資訊作為網路之輸入；輸出數據以螺桿溫升代替螺桿之熱形變量，因熱形變量容易受到馬達端與固定端次兩端固定端的影響產生形變量量測錯誤，因此以螺桿溫升取代螺桿之形變量，然而形變量與溫升之間根據一維的線性膨脹公式，此二者只是單純的比例關係，因此預測出螺桿溫升後只須根據一比例關係預測出形變量，其數據是以FEM根據實驗的邊界條件所模擬出來之螺感溫升，螺桿之最大行程為900mm，FEM以每10mm為一單位共91個監測點模擬出螺感溫升，共91個輸出。本研究使用的倒傳遞網路為在MATLAB2017a的環境下建構五層隱藏層結構之網路，每層20個神經元，最佳化函數為比例共軛梯度演算法(Scaled Conjugate Gradient，SCG)；長短期記憶模型為在TensorFlow的學習框架下利用Keras建構了兩層隱藏層結構，每層20個神經元，最佳化函數為RMSProp演算法，兩個網路所設定之目標函數皆為均方差函數(MSE)。網路訓練時取四個工況做訓練與測試，而另外三個工況只單純做測試，其訓練結果以與訓練工況相同之工況做測試時，其最大誤差大約為1°C左右，以非訓練工況之工況做測試時，其最大誤差大約為2°C左右，就預測結果來看已經有一定的準確度。
When the machine tool is processed, it often heats up due to high-speed friction between the parts to cause thermal deformation, which reduces the machining accuracy. Therefore, if the thermal deformation during machining is known in advance, the machine tool can be compensated, effectively. Based on the two-axis platform,the neural network and deep learning techniques are applied to predict the thermal deformation of the ball screw during processing through several fixed monitor values on the two-axis platform.This study used the Backpropagation Network (BPN) and the Long Short-Term Memory Model (LSTM) of the Recurrent Neural Networks, using seven different processing data to train and test the networkroad including three single processing situation and the four composite processing situations. The input data of the network is measured by the experiment data of the motor temperature, the support end temperature, the room temperature, the nut temperature, the room temperature, the nut speed, the nut position, and the distance traveled by the platform; the output data replaces the thermal deformation of the screw by the temperature rise of the screw. Because the thermal deformation is easily affected by the measurement of the motor end and the fixed end. However, according to the one-dimensional linear expansion formula between the thermal deformation and the temperature rise, the two are only the proportional relationship. Therefore, it is predicted that the screw temperature rises only need to predict the thermal deformation according to a proportional relationship. According to the experimental conditions of the FEM, the maximum strock of the screw is 900mm. The FEM simulates the screw temperature rise with a total of 91 monitoring points per 10mm.Total of 91 outputs.In this study,the backpropagation network is a network of five hidden layer structures constructed in the environment of MATLAB2017a. Each hidden layer has 20 neurons, and the optimization function is Scaled Conjugate Gradient (SCG). The long short-term memory model uses the Keras to construct two hidden layer structures in the learning framework of TensorFlow. Each hidden layer has 20 neurons, and the optimization function is RMSProp algorithm. The cost functions set by the two networks are mean square error(MSE). In the network training, four working conditions are used for training and testing,the other three working conditions are only for testing. When the training results are tested under the same working conditions as the training conditions, the maximum error is about 1 °C. When testing in non-training conditions, the maximum error is about 2 °C, and there is a certain degree of accuracy in terms of prediction results
高轉速氣動箔片軸承之箔片剛性設計;The design of foil stiffness of high speed rotation foil air bearing
No full text[[abstract]]微渦輪引擎中，通常使用球軸承或者氣體軸承作為潤滑系統，其應用包含渦輪機、無人飛機、偵蒐載具以及偏遠地區的發電設備，但在長時間以及高轉速的運轉需求下，以氣體軸承較具優勢。球軸承在使用上以滾動元件或液動壓作為潤滑，通常需要有效率的冷卻系統來維持液體潤滑的工作溫度，以確保潤滑系統正常的運作；而氣體軸承以氣體做為潤滑，其性能較不易受到溫度變化的影響。氣體軸承在潤滑系統中具有幾項符合長時間運轉需求的特性，如:無須定期保養、環境忍耐度高、操作溫度廣泛以及具有多種潤滑氣體可供選用，因此在高轉速長時間運轉、高溫操作環境及冷卻系統的考量下，選用箔片氣體軸承作為潤滑系統。 氣體軸承承受軸承負載能力低，因此需要加入彈簧箔片輔助氣膜支撐；利用箔片的變形以及可壓縮流的雷諾方程式作為研究方法，計算最小氣膜厚度與收斂壓力，輔助氣膜支撐軸承負載；其中箔片變形即是箔片剛性的呈現。本研究建立一模擬分析系統，研究工具包含電腦數值計算、箔片剛性量測設備以及Abaqus模擬軟體。研究中，從箔片的參數設計箔片剛性，改變箔片變形以產生足夠的氣膜使轉軸運轉順暢，並在不同軸承負載的需求下，對拱形箔片與片狀箔片做剛性的設計與分析。在研究結果中，利用電腦數值計算、箔片剛性量測設備與模擬軟體建立出箔片剛性設計系統，得出片狀箔片中以鉛直間距、間隙大小以及幾何高度，這三種設計參數能增加箔片剛性，其中以鉛直間距對於箔片剛性的影響最為靈敏；此外，為因應不同的軸承負載，提出大、中、小的軸承負載做拱型箔片與片狀箔片的剛性設計與分析，結果顯示拱型箔片適合用在大負荷，而片狀箔片適用在中、小負荷的情況。
Foil gas bearing have wide industrial applications, mainly in micro-turbine engine and the aircraft industry else. Micro-turbine is the small size of gas turbine, and only equipped with single layer compressor and a turbine, which make the machine system having the advantage of small volume and suitable for high- speed rotating application. Turbine engine also have the need for long-time running lubrication system. Most important, air foil have remarkable potential for both aspect. This research project applies a lubrication system to meet the technology vision; developing a 80kg-thrust micro-turbine engine in the use of micro-turbine generator, small high-speed target drone, life propulsion system of standard high speed trap and long high speed rotating operations. In the application of high speed micro-turbine engine, the micro-turbine power system has the long running time requirements with the rotating speed up to 90,000 to 100,000 rpm and life needs ( for 30kW ) over 30,000 hours, so the primary is to choose a proper bearing lubrication system in the need of high speed and long time rotating. From the previous research, knowing spindle rotates in high speed and usually works in the environment of high temperature. Applying rolling or fluid hydrodynamic bearing, we need to use an efficient cooling system to make sure bearing working performance. Foil gas bearing isn’t vulnerable to temperature change, so we don’t need the cooling system in the allowable temperature range of foil material. Therefore we choose foil gas bearing, having high speed rotation and long-time operation, as the lubrication system and hope to enhance power efficiency and life-cycle of micro-turbine generator . We need lots of experience for the bearing design because it’s complicated to manufacture. For the purpose of making shaft lift, we set up a simulation and analysis system. Therefore, it’s needed to use related patent and article as reference and then take the calculation of experiment trend and result of simulation into account to analysis. After, provide the analysis result with reference data for research organization. While the design of the foil is the key aspect of affecting the performance of foil gas bearings, this research start with surface roughness of top foil and use the full-film hydrodynamic lubrication theory to calculate the minimum film thickness used for supporting shaft lifting. Try to reach the stiffness in the theory calculation with the calculation of programming language and design geometry foil for stiffness. Studying research analysis on present bump foil is also necessary. Eventually, hope to enhance the load capacity and reliability of foil gas bearing in real working
初探刮刀塗佈之bow-wave分析;
No full text[[abstract]]本論文針對刮刀塗佈之刮刀前興起的bow-wave流場進行分析。在不可壓縮牛頓流體的條件下，先將Navier-Stokes equation與Continuity equation簡化為二維流場，再對其進行無因次化分析，進而提出簡化後的磨潤模型。邊界條件採用了基板不滑移邊界條件、自由面零剪應力邊界條件、自由面的表面張力之Laplace pressure、流場入口等速流條件。針對自由面隨時間變化的bow wave，則採用自由面運動學條件(kinematic moving free surface condition)。理論上，將bow wave自由面輪廓當作未知參數的情況下，對上述磨潤模型與邊界條件求解，可以將自由面下的速度場與壓力場表示為bow wave自由面輪廓的函數。再將此速度場帶入bow wave自由面運動學邊界條件，即可以得到統御bow wave自由面輪廓的偏微分方程。對此bow wave自由面輪廓的偏微分方程求解後，即完成刮刀塗佈之bow wave流場分析。實際上，我們無法將自由面下的速度場與壓力場表示為bow wave自由面輪廓的解析函數，而是必須滿足一約束方程的隱函數。因此我們利用正交配置法將此約束方程和統御bow wave自由面輪廓的偏微分方程分別降階為約束的代數方程和常微分方程。接著利用時間超前差分法(time forward difference)，以疊代方式解出隨時間變化的速度場與壓力場，以及bow wave自由面輪廓。然而，根據上述刮刀塗佈的bow wave流體模型解出的理論解，在初始bow wave自由面輪廓為一斜平面時，其bow wave自由面的高度會隨著時間慢慢下降，最後降為一水平面，這與我們實驗觀察到的結果不相符。可能原因應是少了bow wave出口端與刮刀接觸的邊界條件。而此條件應由刮刀下流場來表示，因此下階段可能工作也許是將以上bow wave模型與刮刀下塗佈流體模型整合，再對所得到的聯立偏微分方程進行求解，一併求得bow wave下與刮刀下流體行為。
In this thesis, we analyze the bow-wave flow field that arises before the blade coating. Under the condition of incompressible Newtonian fluid, the Navier-Stokes equation and Continuity equation are first simplified into a two-dimensional flow field, and then the dimensionless analysis is carried out, and then the simplified lubrication model is proposed. The boundary conditions are the substrate non-slip boundary condition, the free surface zero shear stress boundary condition, the Laplace pressure of the free surface tension, and the flow field inlet constant velocity condition. For a bow wave whose free surface changes with time, a kinematic moving free surface condition is employed.In theory, if the bow wave free surface profile is treated as an unknown parameter, the velocity field and the pressure field under the free surface can be expressed as a function of the bow wave free surface profile. Then the velocity field is brought into the bow wave free surface kinematic boundary condition, that is, the partial differential equation of the bow wave free surface contour can be obtained. After solving the partial differential equation of the bow wave free surface profile, the bow wave flow field analysis of the blade coating can be completed.In fact, we cannot express the velocity field and pressure field under the free surface as the analytic function of the bow wave free surface contour, but must satisfy the implicit function of a constraint equation. Therefore, we use the orthogonal collocation method to reduce the constraint equations and the partial differential equations of the bow wave free surface contour to the constrained algebraic equations and ordinary differential equations. Then, using the time forward difference, the velocity field and the pressure field as a function of time and the bow wave free surface profile are solved in an iterative method.However, according to the theoretical solution solved by the above-mentioned blade-coating bow wave fluid model, when the initial bow wave free surface profile is an oblique plane, the height of the bow wave free surface gradually decreases with time, and finally decreases to one horizontal plane, which is inconsistent with the results observed in our experiments. The possible reason should be that there is less boundary condition between the outlet end of the bow wave and the blade. This condition should be represented by the flow field under the blade. Therefore, the next stage may work by integrating the above bow wave model with the coating fluid model under the blade, and then solving the obtained simultaneous partial differential equation and obtaining the bow wave, fluid behavior under the wave and under the blade together
進給系統健康診斷技術之研發;Developments of Fault Detection Techniques for Ball Screw Feed Drive Systems
No full text[[abstract]]本研究目的為發展進給系統健康診斷系統。在進給系統中最容易發生故障的部分為滾珠螺桿之預壓力消失，其次為滾動軸承，而軸承故障主要原因為裝配不當及元件損毀，因此本研究主要針對滾動軸承之組裝與元件進行健康狀態分析，共分為三個部分。第一部分發展頻帶能量特徵方法，利用軸承振動訊號，經解調後取得其包絡譜，再引用頻帶切割與掃頻的概念提取有效的頻域特徵，結合取樣熵(Sample Entropy, SE)、方均根(Root mean square, RMS)及奇異譜熵(Singular Spectrum Entropy, SSE)等時域特徵對軸承進行健康診斷。第二部分使用全息譜觀察滾動軸承運轉時軌跡之變化，並提取能代表軸承旋轉情形之振動特徵，進而針對組裝之機械故障進行狀態監測，避免因裝配問題造成軸承使用壽命減短，可及時調整組裝方式並解決問題。第三部分將軸承振動訊號提取之特徵以自組織映射圖(Self-Organizing map, SOM)建立健康模型，再透過計算待測資料與健康模型之最小量化誤差(Minimum quantization error, MQE)來量化軸承及組裝狀態，並結合移動窗與馬式距離(Mahalanobis distance)的概念對軸承進行長期監控，觀察軸承之全生命週期狀態與預防突發之異常狀況。最後，透過SOM結合時、頻域特徵與全息譜同步對軸承組裝及滾動軸承狀態進行健康診斷，並引用2012PHM集NASA軸承疲勞實驗數據集進行驗證，由實驗結果證明，此進給系統健康診斷技術能有效提升狀態估測準確度。
The purpose of this research is to develop a diagnosis system for ball screw feed drive systems. The most prone to failure component in the feed drive system is the preload loss, followed by the rolling bearings. Furthermore, the main cause of the bearing failure is the installation error and/or component damage. The thesis consists of three parts. In the first part, several features extracted from the vibration measurements in frequency domain and time domain such as Sample entropy (SE), Root mean square (RMS), Singular spectrum entropy (SSE) and band energy are compared for their effectiveness in diagnosing the ball bearing faults. In the second part, features which could represent the assembly condition of the ball screw feed drive systems such as misalignment using the holographic spectrum are proposed and their effectiveness are also investigated. Finally, all the features aiming to detecting faults of ball screw feed drive systems due to bearing and/or assembly extracted from the vibration measurements are merged using Self-organizing map (SOM) . Whether the ball screw feed drive systems is healthy can be determined by calculating the Mahalanobis distance according to the Minimum quantization error (MQE) from the SOM. The proposed diagnosis technique is validated using the data sets from PHM and NASA. Experimental results show that the ball screw feed drive system can be diagnosed with a reasonable accuracy by this system