Browsing by Issue Date, starting with "2017-07-15"
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Item type:Item, Item type:Item, Differential Feedback of Geometrical Mean Decomposition Precoder for Time-Correlated MIMO Systems(2017-07-15) ;Chen, Hung-Chun ;Lin, Yuan-Pei ;電機工程學系Department of Electrical and Computer EngineeringFor a time-correlated channel, we consider the differential feedback of the geometrical mean decomposition (GMD) precoder, which is known to be optimal for a number of criteria. When the channel varies slowly, we can expect the optimal GMD precoders of consecutive channel uses to be close. We consider the feedback of the so-called differential precoder and show that it lies in a neighborhood of the identity matrix using matrix perturbation theory. Furthermore, the radius of the neighborhood is shown to be proportional to a time-correlation parameter. Such a characterization allows for subsequent efficient quantization of the differential precoder. We show how to design codewords for the prescribed radius by perturbing the identity matrix and applying QR decomposition on the perturbed matrix. Simulations are given to demonstrate that, with a small feedback rate, the performance of the proposed differential GMD comes close to the case when perfect channel state information is available to the transmitter for slowly time-varying channels like those in indoor and microcellular environments.Item type:Item, 編輯曲線 混沌與複雜說不完的好故事(國立交通大學丘成桐中心, 2017-07-15)編輯室本雜誌將從這一期開始恢復為半年刊,若造成讀者的不便,敬請海涵。專題《秩序與複雜的華爾滋》上期的重點在數學本身,本期則放在各種應用。Item type:Item, Item type:Item, Item type:Item, Item type:Item, Item type:Item, Item type:Item, Item type:Item, 甚麼是橢圓曲線?(國立交通大學丘成桐中心, 2017-07-15)王夏聲在數論、代數幾何、複分析、密碼學和物理等領域的研究裡,橢圓曲線(elliptic curve)無所不在。橢圓曲線也是算術幾何(arithmetic geometry)的研究前沿,出現在懷爾斯(Andrew Wiles)的費馬最後定理證明中(請參見本期〈2016 年阿貝爾獎得主懷爾斯訪談〉)。Item type:Item, Item type:Item, 數理簡訊 2017 年數學大獎(國立交通大學丘成桐中心, 2017-07-15)編輯室2017 年阿貝爾獎頒給法國沙克雷(原卡尚)高等師範學院的梅耶爾(Yves Meyer),得獎理由是基於「他在小波〔wavelet〕數學理論中的樞紐角色」,跨越了數學、計算科學和資訊科技領域。Item type:Item, Item type:Item, Item type:Item, 專題-秩序與複雜的華爾滋(下) 勞倫茲和蝴蝶共同掀起的混沌風暴(國立交通大學丘成桐中心, 2017-07-15)陳義裕一提到混沌,人們第一個想到的可能就是著名的「蝴蝶效應」。但除了得感激科普作家的辛勤筆耕,真正讓蝴蝶效應這個混沌代名詞得以如此流傳、深入人心的,恐怕還是得拜幾部好萊塢電影所賜,其中尤以 1993 年的賣座電影《侏羅紀公園》最為著名。在該部電影中,數學家主角所述蝴蝶效應指的是:北京的一隻蝴蝶隨便搧個翅,結果竟為本來應該是大晴天的紐約帶來豪雨。Item type:Item, Widely wavelength tunable fast intensity-modulated light source for biophotonic applications(2017-07-15) ;Huang, Tzu-Feng ;Tseng, Sheng-Hao ;Wang, Hsien-Yi ;Chan, Ming-Che光電學院High modulation depth, fast (megahertz to gigahertz), intensity-modulated light sources of various wavelengths within the 0.7-1.35 mu m bio-penetration window are highly desirable for many biophotonic diagnosis systems. In this Letter, we present a novel scheme of a wavelength tunable, ultra-broadband light source which simply consists of a pump laser, a nonlinear fiber, and demodulation circuits. The working wavelength range of the light source is from 0.7 to 1.35 mu m which covers a vast part of the bio-penetration window, and its modulation frequencies extends from tens of megahertz to gigahertz. The performances of the proposed light source in either working wavelength range or modulation frequency bandwidth are much superior to any typical laser diodes or solid state lasers currently employed in the frequency-domain or other biophotonic utilization. The wide applicability of this novel light source in diverse biophotonic applications can be observed from our carefully designed diffused optical spectroscopy phantom measurement. (C) 2017 Optical Society of AmericaItem type:Item, 滴點式複合藥物凝膠及其製備方法(2017-07-16) ;劉典謨王依齡本發明提供一種滴點式複合藥物凝膠,包含複數 個幾丁聚醣微胞、鹼性結構安定劑以連接複數個幾丁聚醣微胞、第一藥物於複數個幾丁聚醣微胞之內、以及第二藥物於複數個幾丁聚醣微胞之外。Item type:Item, 用於控制行走輔具的方法(2017-07-16) ;宋開泰 ;吳尚陽江信毅一種用於控制行走輔具的方法,利用雷射掃描儀來偵測使用者的步態資訊,並利用力矩感測器來偵測使用者的施力方向,作為行走輔具運動控制的輸入資訊,進而運用順應性控制來達成行動輔助的功效。其中以使用者的步態資訊調整行走輔具的移動速度,而以力矩感測資訊調整行走輔具的行進方向,能產生行走輔具所需的被動行為,有效達成助行之功能。此外,本發明還提供一種行走輔具的自主避障機制,藉由結合該自主避障機制與上述的順應性控制,能讓行走輔具在複雜的環境中避免碰撞障礙物,提供使用者更安全的操作。Item type:Item, 光學量測系統及其濃度感測裝置(2017-07-16) ;孟心飛 ;冉曉雯 ;鄭宏志 ;蔡美娟周哲宇一種光學量測系統,其適於量測待測物的濃度。光學量測系統包括濃度感測裝置、光源以及光偵測器。濃度感測裝置包括濃度偵測膜、入光波導以及出光波導。入光波導以及出光波導分別耦接於濃度偵測膜。濃度感測裝置由入光波導的入光端接收來自光源的第一光束,且濃度感測裝置由出光波導的出光端輸出第二光束至光偵測器。在濃度偵測膜與待測物反應後,第二光束的光強度指示待測物的濃度。另提供光學量測系統及其濃度感測裝置。Item type:Item, Risk of gestational hypertension-preeclampsia in women with preceding endometriosis: A nationwide population-based study(2017-07-17) ;Pan, Mei-Lien ;Chen, Li-Ru ;Tsao, Hsiao-Mei ;Chen, Kuo-Hu機械工程學系Objective To investigate the association between preceding endometriosis and gestational hypertension-preeclampsia (GH-PE). Methods In this nationwide population-based longitudinal study, data from 1998-2012 Taiwan National Health Insurance Research Database were used. We used ICD9-CM codes 617.X and 642.X respectively for the diagnoses of endometriosis and GH-PE, which were further confirmed by examining medical records of surgeries, blood pressure and urine protein to ensure the accuracy of the diagnoses. The study excluded women diagnosed with endometriosis at < 15 or > 45 years of age, chronic hypertension, and GH-PE prior to endometriosis. Each pregnant woman with a prior diagnosis of endometriosis was matched to 4 pregnant women without endometriosis by age. Logistic regression analysis was used to calculate odds ratios (ORs) for the risk of GH-PE with adjustment for age, occupation, urbanization, economic status and comorbidities. Results Among 6,300 women with a prior endometriosis diagnosis who were retrieved from a population of 1,000,000 residents, 2,578 (40.92%) had subsequent pregnancies that were eligible for further analysis and were compared with 10,312 pregnant women without previous endometriosis. GH-PE occurred more in women with prior endometriosis as compared to those without endometriosis (3.88% vs. 1.63%, p<0.0001). Further analysis revealed prior endometriosis was associated with GH-PE (adjusted OR = 2.27; 95% CI: 1.76-2.93). For danazol-treated and non-danazol-treated subgroups, the incidences of GH-PE were 3.13% (15/480) and 4.05% (85/2,098), respectively. Although the risk for subsequent GH-PE was lower (adjusted OR = 1.49; 95% CI: 0.86-2.56) after receiving danazol treatment than average (adjusted OR = 2.27; 95% CI:1.76-2.93) for women with preceding endometriosis, the reduction of risk was not statistically remarkable for danazol-treated (adjusted OR = 1.49) vs. non-danazol-treated (adjusted OR = 2.48) subgroups (p heterogeneity = 0.12). Conclusions Preceding endometriosis is an independent and significant risk factor for the occurrence of GH-PE.