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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

在點對點網路上針對串流資料傳播的品質保證 / Quality assurance of streaming data dissemination over p2p network

邱威中, Chiu, Wei Chung Unknown Date (has links)
網路技術發展的日新月異帶領了眾多新網路服務的崛起,例如即時影音串流這類的多媒體服務。但即時影音串流服務所產生的龐大資料流和傳輸延遲時間的嚴格限制也隨之而來的為網路環境帶來許多挑戰,在這些條件下,傳統Server-client拓樸架構將client要求的影音資料以單一鏈結傳輸時,常會因為頻寬不足而面臨嚴重的封包遺失,或是資料流擁擠造成的額外傳輸延遲使得封包無法達到即時性的需求。P2P網路擁有server-client架構所難以達到的規模伸縮性,且對於節點、鏈結失效所引起的傳輸錯誤也較能容忍,更重要的是,它有效的分散了原本負載在少數link上的龐大資料流。因此P2P架構近年來風行於即時影音串流服務。 目前P2P網路的拓樸多是隨意形成,當網路成員規模龐大時,由傳送端出發到遠方的接收端,途中可能經過無數的鏈結,每一個鏈結都會由於頻寬的不足使得資料流遭受某種程度的品質損害,另一方面,對即時影音服務而言,若資料流的累積延遲時間超出可容忍範圍時,無法為使用者接受。 本研究嘗試找出一個較好的拓樸用以傳輸多媒體資料流,使得位於最遠端節點的累積延遲亦能為使用者接受,且資料品質的損害程度最小。我們將之建置成一NP-Complete複雜度的問題模型,名為MLDST。而解法則是修改Dijkstra single-source shortest-path演算法,並加上每個節點承擔下游節點數量及延遲時間限制而來。我們以PlanetLab環境在實際的網路上進行實驗,證實我們的演算法比傳統的Minimum-Spanning Tree及shortest path spanning tree有更好的影像品質。 / Numerous new network services arise with the advanced development of network technologies, such as real-time multimedia streaming services. But challenges to network environment come along with the enormous traffic of data flows and rigorous restriction to transmission delay of real-time multimedia streaming services. Under this circumstance, conventional server-client topology suffers from serious packet loss and packet delay due to the overload of servers and their accessing links. Also, extra transmission delay may make packets fail to meet the requirement of real-timed services. Peer-to-peer network is more scalable than server-client model, and is much more tolerable to the transmission errors caused by node or link failures. More importantly, it effectively distributes load from the server to peers. As a consequence, peer-to-peer service architecture becomes very popular for real-time multimedia streaming services recently. Peer-to-peer networks are mostly formed in random fashion. As the size of network grows, packets may have to travel through numerous links to reach far-end receivers. The quality of data may be damaged by insufficient bandwidth of links. For real-time multimedia services, it is not acceptable to users if the cumulated packet delay exceeds a tolerable limit. Our research is trying to find a better topology to transmit multimedia data flows which makes the cumulated delay of the most-far-end user be tolerable and the damage of data quality is minimized. The problem is modeled as a MLDST problem, which is a NP-Complete problem. To solve the problem, we modified Dijkstra’s single-source shortest-path algorithm by bounding the node degree and adding delay constraint. The experiments were carried out on real network environment through PlanetLab. Experiments show that our algorithm outperforms traditional MST and shortest path spanning tree.
12

Implied Volatility Function - Genetic Algorithm Approach

沈昱昌 Unknown Date (has links)
本文主要探討基因演算法(genetic algorithms)與S&P500指數選擇權為研究對象,利用基因演算法的模型來估測選擇權的隱含波動度後,進而求出選擇權的最適價值,用此來比較過去文獻中利用Jump-Diffusion Model、Stochastic Volatility Model與Local Volatility Model來估算選擇權的隱含波動度,使原始BS model中隱含波動度之估測更趨完善。在此篇論文中,以基因演算法求估的選擇權波動度以0.052的平均誤差值優於以Jump-Diffusion Model、Stochastic Volatility Model與Local Volatility Model求出之平均誤差值0.308,因此基因演算法確實可應用於選擇權波動度之求估。 / In this paper a different approach to the BS Model is proposed, by using genetic algorithms a non-parametric procedure for capturing the volatility smile and assess the stability of it. Applying genetic algorithm to this important issue in option pricing illustrates the strengths of our approach. Volatility forecasting is an appropriate task in which to highlight the characteristics of genetic algorithms as it is an important problem with well-accepted benchmark solutions, the models mention in the previous literatures mentioned above. Genetic algorithms have the ability to detect patterns in the conditional mean on both time and stock depend volatility. In addition, the stability test of the genetic algorithm approach will also be accessed. We evaluate the stability of the new approach by examining how well it predicts future option prices. We estimate the volatility function based on the cross-section of reported option prices one week, and then we examine the price deviations from theoretical values one week later.
13

基於雲端環境與服務導向架構之交易策略評估平台框架

楊雅菱 Unknown Date (has links)
本研究利用雲端運算的技術,發展大量使用者使用的策略交易的系統。為滿足大量使用者的運算需求,本系統包括幾項特性: 1. 採用服務導向架構以充分使用雲端運算的特性。 2. 建立非同步事件控制機制以提供服務間非同步運算能力。 3. 採用集中式資料結構,提出收縮式肋骨網絡(SRN)資料結構,減少運算需求。 4. 提供基因演算模擬環境,讓使用者可以發展符合個人投資偏好的投資策略。 / In this study, we designed a algorithmic trading system for large numbers of users on a cloud computing plateform. So the main features of the algorithmic trading system have been as follows. 1. The use of Service-Oriented architecture in order to fully use the characteristics of cloud computing. 2. The establishment of asynchronous event control mechanism to provide services to non-synchronous computing power. 3. A centralized data structure, proposed Systolic Ribs Network (SRN) data structure, reducing the computing needs. 4. To provide the genetic algorithm simulation environment that allows users to develop in line with the investment strategy personal investment preferences.
14

資料採礦於資訊流通業(B2B)之應用研究—以個案公司為例

陳炳輝, Chen, Ping-Hui Unknown Date (has links)
所謂資料採礦是指『從大量資料或大型資料庫中由電腦自動選取一些重要的、潛在有用的資料類型或知識』。目前資料採礦所包含的各種技術已被廣泛的應用在許多領域上,本研究即要利用資料採礦的技術從大量的客戶交易資料中採掘出客戶與商品之間的關聯性知識,並將之應用未來客戶銷售活動。 資料採礦於流通業多為B2C之應用,本研究則嘗試將資料採礦分析應用於B2B之交易分析,並以個案公司與其客戶之實際銷售資料為本研究之資料來源,本研究利用Clementine電腦軟體為資料採礦工具,並依分析目的之不同,運用該軟體提供之各項採礦模組分別對個案公司之交易資料進行分析,如: *.使用關聯網〈web〉的方式,針對個案資料,尋找商品銷售間的強弱關係,挑出銷售關聯性較高的商品組合,並且利用C5.0決策樹演算法,尋找該交易行為的對象之特性為何。 *.使用Apriori演算法,針對BZ(商圈)、DL(經銷商)、SP(門市)等不同客戶類型在不同的資料期間,找出資料中所有商品之關聯規則。 *.利用Apriori演算法,利用前半年資料,找出IFAKMB(主機板)、IFDDLC(LCD監視器)、IFCOCP(中央處理器)等類別商品的購買規則,並分別以後半年的資料進行驗證,探究此規則之可行性。 接著針對各項資料採礦結果,就個案公司之實際狀況進行解讀,同時更重要的是探討該分析結果應用於銷售實務上之可行性,如:產品銷售規則,行銷策略、促銷戰術之擬定等。最後並以本研究之結果及經驗,對個案公司提出資訊管理系統資料補強之建議及資料採礦於未來可再延伸探討之應用方向。
15

Risk Preference, Forecasting Accuracy and Survival Dynamics:Simulations Based on a Multi-Asset Agent-Based Artificial Stock Market / 風險偏好與預測能力對於市場生存力的重要性

黃雅琪, Huang, Ya-Chi Unknown Date (has links)
風險偏好與預測精確性對生存力的重要性吸引進來許多理論學者的注意。一個極端是認為風險偏好完全不重要,唯一重要是預測精確性。然而此乃基於柏拉圖最適配置之下。透過代理人基模型,我們發現相異的結果,即風險偏好在生存力上扮演重要角色。 / The relevance of risk preference and forecasting accuracy to the survival of investors is an issue that has recently attracted a number of recent theoretical studies. At one extreme, it has been shown that risk preference can be entirely irrelevant, and that in the long run what distinguishes the agents who survive from those who vanish is just their forecasting accuracy. Being in line with the market selection hypothesis, this theoretical result is, however, established mainly on the basis of Pareto optimal allocation. By using agent-based computational modeling, this dissertation extends the existing studies to an economy where adaptive behaviors are autonomous and complex heterogeneous, and where the economy is notorious for its likely persistent deviation from Pareto optimality. Specifically, a computational multiasset artificial stock market corresponding to Blume and Easley (1992) and Sandroni (2000) is constructed and studied. Through simulation, we present results that contradict the market selection hypothesis. Risk preference plays a key role in survivability. And agents who have superior forecasting accuracy may be driven out just because of their risk preference. Nevertheless, when all the agents are with the same preference, the wealth share is positively correlated to forecasting accuracy, and the market selection hypothesis is sustained, at least in a weak sense.
16

以Web2.0民眾分類法建置音樂推薦系統之研究 / A Music Recommendation System Based on the Web 2.0 Folksonomy Approach

鄭學侖, Cheng,Allen Unknown Date (has links)
近年來,數位格式的音樂使得音樂市場活動逐漸由實體轉移到線上,消費者也開始會透過線上服務自己搜尋並取得在網路上大量的音樂。但是由於過量的音樂資訊,使得消費者在下載音樂試聽後,往往真正會去購買的比例是微乎極微,因此造成唱片業者對於音樂下載的觀點仍非常保守。因此,如何去提升在消費者下載之歌曲數量與真正消費之音樂的比例,將是線上音樂市場的一項發展重點。 本研究希望透過近年在Web 2.0網站上常見之標籤系統,實作一個由群眾定義音樂分類的音樂資訊交流平台,並基於此標籤式的分類法,發展一套推薦系統,來提高消費者接觸到喜歡之音樂的比例,近一步解決上述之問題。在系統發展中,本研究提出一套用於推薦系統之演算法則,並在建置之實驗音樂資訊交流平台上驗證其可行性。最後,本研究亦針對未來研究議題方向,提出一些建議。
17

基於個人電腦使用者操作情境之音樂推薦 / Context-based Music Recommendation for Desktop Users

謝棋安, Hsieh, Chi An Unknown Date (has links)
隨著電腦音樂技術的蓬勃發展,合乎情境需求的音樂若被能自動推薦給使用者,將是知識工作者所樂見的。我們提出了一個定義使用者操作情境的情境塑模,定義使用者操作情境,並利用累計專注視窗的轉變,找出使用者的操作情境。同時,我們也提出了音樂推薦塑模,依據使用者的操作情境與聆聽的音樂,分析探勘情境與音樂特徵間的關聯特性,利用探勘出的關聯推薦適合情境的音樂給使用者。在此音樂推薦塑模中,我們採用Content-based Recommendation的作法。我們分析音樂的特徵值,並發展MAML(Multi-attribute Multi-label)的分類演算法以及Probability Measure二種方法來探勘情境屬性與音樂特徵間的關聯特性。根據探勘出的關聯特性,找出適合情境的音樂特徵,再從音樂資料庫中推薦符合音樂特徵的音樂給使用者。本論文的符合使用者操作情境的音樂推薦系統是利用Windows Hook API實作。經實驗證明,本論文方法在符合情境的音樂推薦上,擁有近七成準確率。 / With the development of digital music technology, knowledge workers will be delighted if the music recommendation system is able to automatically recommend music based on the operating context in the desktop. The context model and context identification algorithm are proposed to define the operating context of users and to detect the transition of context based on the changes of focused windows. Two association discovery mechanisms, MMAL (Multi-attribute Multi-label) algorithm and PM (Probability Measure), are proposed to discover the relationships between context features and music features. Based on the discovered rules, the proposed music recommendation mechanism recommends music to the user from the music database according to the operating context of users. The context-based recommendation system is implemented using Windows Hook API. Experimental results show that near 70% accuracy can be achieved.
18

一個基於記憶體內運算之多維度多顆粒度資料探勘之研究-以yahoo user profile為例 / A Research of Multi-dimensional and Multigranular Data Mining with In-memory Computingwith yahoo user profile

林洸儂, Lin, Guang-Nung Unknown Date (has links)
近年來雲端運算技術的發展與電腦設備效能提升,使得以大量電腦主機以水 平擴充的方式組成叢集運算系統,成為一可行的選擇。Apache Hadoop 是Apache 基金會的一個開源軟體框架,它是由Google 公司的MapReduce 與Google 檔案 系統實作成的分布式系統,可以管理數千台以上的電腦群集。Hadoop 利用分散 式檔案系統HDFS 可以提供PB 級以上的資料存放空間,透過MapReduce 框架 可以將應用程式分割成小工作分散到叢集中的運算節點上執行。 此外,企業累積了巨量的資料,如何處理與分析這些結構化或者是非結構化 的資料成了現在熱門研究的議題。因此傳統的資料挖掘方式與演算法必須因應新 的雲端運算技術與分散式框架的概念,進行調整與改良,發展新的方法。 關聯規則是分析資料庫龐大的資料中,項目之間隱含的關聯,常見的應用為 購物籃分析。一般情形下會在特定的維度與特定的顆粒度範圍內挖掘關聯規則, 但這樣的方式無法找出更細微範圍下之規則,例如挖掘一個年度的交易資料無法 發現消費者在聖誕節為了慶祝而購買的商品項目間的規則,但若將時間限縮在 12 月份即可挖掘出這些規則。 Apriori 演算法是挖掘關聯規則的一個著名的演算法,透過產生候選項目集 合與使用自訂的最小支持度進行篩選,產生高頻項目集合,接著以最小信賴度篩 選獲得關聯規則的結果。若有k 種單一項目集合,則候選項目集合最多有2𝑘 − 1 個,計算高頻項目時則需反覆掃描整個資料庫,Apriori 這兩個主要步驟需要耗費 相當大量的運算能力。 因此本研究將資料庫分割成多個資料區塊挖掘關聯規則,再將結果逐步更新 的演算法,解決大範圍挖掘遺失關聯規則的問題,結合spark 分散式運算的架構 實作程式,在電腦群集上平行運算減少關聯規則的挖掘時間。 / Because of improving technique of cloud-computing and increasing capability of computer equipment, it is feasible to use clusters of computers by horizon scalable a lot of computers. Apache Hadoop is an open-source software of Apache. It allows the management of cluster resource, a distributed storage system named Hadoop Distributed File System (HDFS), and a parallel processing technique called MapReduce. Enterprises have accumulated a huge amount of data. It is a hot issue to process and analyze these structured or unstructured data. Traditional methods and algorithms of data mining must make adjustments and improvement to new cloud computing technology and concept of decentralized framework. Association rules is the relations of items from large database. In general, we find association rules in fixed dimensions and granular database. However, it might loss infrequent association rules. Apriori algorithm is one famous algorithm of mining association rule. There are two main steps in this algorithm spend a lot of computing resource. To generate Candidate itemset has quantity 2𝑘 − 1, if there are k different item. Second step is to find frequent, this step must compare all tractions in the database. This approach divides database to segmentations and finds association rules of these segmentations. Then, we combine rules of segmentations. It can solve the problem of missing infrequent itemset. In addition, we implement this method in Spark and reduce the time of computing.
19

應用文字探勘技術於臺灣上市公司重大訊息對股價影響之研究 / The study on impact of material information of public listed company to its stock price by using text mining approach

吳漢瑞, Wu, Han Ruei Unknown Date (has links)
台灣股票市場屬於淺碟型,因此外界的訊息易於影響股價波動;同時台灣是一個以個別投資人為主的散戶市場,外界的訊息會影響市場投資。因此,重大訊息的發布對公司股價變化的影響,值得我們進一步探討。 本研究以公開資訊觀測站之重大訊息為資料來源,蒐集2005~2009年間統一、中華電信、長榮航空以及臺灣企銀四間上市公司之重大訊息共1382篇。利用文字探勘kNN演算法將四間公司之重大訊息加以分群,分析出各訊息的發布對於股價之影響程度,並找出不同群組之重大訊息的漲跌趨勢,期能對未來即時重大訊息的發布,分析出其對於股價之漲跌影響,進一步得到訊息發布日後兩日之報酬率走勢,成為日後投資標的之選擇參考。 本研究結果顯示取樣公司於發布前兩日至發布後兩日,交易量有顯著之異常,顯示訊息發布對於公司股票確有影響;而不同的重大訊息內容,將會被分於不同之群組當中,各群組也各有其不同之漲跌趨勢,本研究於測試資料之分類結果,整體平均有六成五之準確率,在於上漲類別之準確率更高達八成;最後於發布後累積報酬率之影響,投資正確率平均高於六成。 本研究透過系統化之分析與預測,省去投資者對於重大訊息之搜尋以及解讀的時間,提供投資者一個可供參考之依據。 / In this study we used the technique of text mining to classify the material information of companies and analyze how the disclosure of it affects the market. Hence, we would be able to predict the price of stock based on disclosures of the material information and then use the outcome as reference of investment. This study chose the Market Observation Post System as the source of information to its justice. We chose UNI-PRESIDENT ENTERPRISES CORP, Chunghwa Telecom Co., Ltd, EVA AIRWAYS CORPORATION and Taiwan Business Bank for their great evaluation of the information disclosure. We collected 1382 material information from 2005 to 2009 and for the better performance, we selected kNN algorithm as our rule of classification. We conducted three experiments in this study. In these experiments, we have approved that the trading volume of two periods were with significant differences. We have over 60% accuracy of the all data to classify the tested data. As a result, we found that the return rate of the “up” group has over 60% upside probability and the “down” group has over 60% downside probability. In this study, we built a time-saving automatic system to group material information and find out those that are valuable. Based on our result, we provided a reference to investors for their investment strategy. At the same time, we also came up with some inspiration for future research.
20

運用演化範例學習法進行台灣股票上市公司經營績效判斷之研究

陳柏明 Unknown Date (has links)
國立政治大學研究所八十七學年度第二學期碩士論文提要 研究所別:資訊管理學系碩士班 研究生:陳柏明 指導教授:楊建民博士 論文名稱:運用演化範例學習法進行台灣股票上市公司經營績效判斷之研究 論文提要內容 股票上市公司的經營績效,對於廣大的投資人、以及銀行及債權人,甚至是公司內的管理人員來說,都是相當重要的資訊。投資大眾可以做為投資計畫的參考,銀行及債權人能對授信及放款制訂適當的準則與採取必要的措施。而公司內部管理階層若能及早發現問題,更可針對問題訂定未來的營運計畫,確保公司的穩定。公司經營績效的評量方法有很多,通常採用財務報表分析來瞭解公司的財務狀況與經營成果。本研究則提出一個演化範例學習法的架構,用來分析財務報表所能提供的資訊,進而判斷公司經營績效。 範例學習法透過線索的選定並對例子集加以分類,進而得到法則。線索的選取將會對決策樹的建立有極大的影響,因此如何得到優良且適當的線索,是在建立決策樹時的重要工作。而遺傳演算法提供了一種演化的方式,透過其演化的機制,一步步的尋找較佳的近似解,因此可以用來進行範例學習法的建樹過程的演化,並改良線索的選用,此架構稱為演化範例學習法。因此本研究希望透過演化式的範例學習法來分析財務報表申所報導的各項財務資料所能提供之資訊。並選取台灣地區股票上市公司之財務報表進行分析,研究所得的結論在於判斷未來這些公司經營績效之變化,讓投資者、債權人與公司管理人員能夠及早因應並採取有效的措施。 本研究以民國七十六年至民國入十七年的股票上市公司財務比率資料進行演化實驗。測試結果顯示 (1)採用本演算法分析績效的命申率可達六成以上,最"高可達到約七成,且在一定的世代內,命申率將隨著逐步提升,(2)初始線索的選取不影響演化後期的命申率,(3)淘汰率高低將造成演化過程命申率的波動程度,(4)由新線索的加入,發現每股淨值、淨值報酬率等以往較不常使用的線索具有一定的分析能力。最後並將針對本研究提出相關建議與未來值得研究的課題。

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