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Self-Learning Based Image Decomposition with Applications to Single Image Denoising
No full text[[abstract]]Decomposition of an image into multiple semantic components has been an effective research topic for various image processing applications such as image denoising, enhancement, and inpainting. In this paper, we present a novel self-learning based image decomposition framework. Based on the recent success of sparse representation, the proposed framework first learns an over-complete dictionary from the high spatial frequency parts of the input image for reconstruction purposes. We perform unsupervised clustering on the observed dictionary atoms (and their corresponding reconstructed image versions) via affinity propagation, which allows us to identify image-dependent components with similar context information. While applying the proposed method for the applications of image denoising, we are able to automatically determine the undesirable patterns (e.g., rain streaks or Gaussian noise) from the derived image components directly from the input image, so that the task of single-image denoising can be addressed. Different from prior image processing works with sparse representation, our method does not need to collect training image data in advance, nor do we assume image priors such as the relationship between input and output image dictionaries. We conduct experiments on two denoising problems: single-image denoising with Gaussian noise and rain removal. Our empirical results confirm the effectiveness and robustness of our approach, which is shown to outperform state-of-the-art image denoising algorithms.[[fileno]]2030144010033[[department]]電機工程學
A Control-Theoretic Approach to Rate Adaption for DASH Over Multiple Content Distribution Servers
No full text[[abstract]]Recently, dynamic adaptive streaming over HTTP (DASH) has been widely deployed on the Internet. However, the research about DASH over multiple content distribution servers (MCDS-DASH) is limited. Compared with traditional single-server DASH, MCDS-DASH is able to offer expanded bandwidth, link diversity, and reliability. It is, however, a challenging problem to smooth video bitrate switching over multiple servers due to their diverse bandwidths. In this paper, we propose a block-based rate adaptation method considering both the diverse bandwidths and feedback buffered video time. In our method, multiple fragments are grouped into a block and the fragments are downloaded in parallel from multiple servers. We propose to adapt video bitrate at the block level rather than at the fragment level. By dynamically adjusting the block length and scheduling fragment requests to multiple servers, the requested video bitrates from the multiple servers are synchronized, making the fragments download in an orderly way. Then, we propose a control-theoretic approach to select an appropriate bitrate for each block. By modeling and linearizing the rate adaption system, we propose a novel proportional-derivative controller to adapt video bitrate with high responsiveness and stability. Theoretical analysis and extensive experiments on our network testbed and the Internet demonstrate the good efficiency of the proposed method.[[fileno]]2030144010035[[department]]電機工程學
Synthesis Of Subfemtosecond Periodic Waveforms
Get PDF[[abstract]]Periodic optical waveforms of arbitrary shape in the femtosecond and subfemtosecond time scale are synthesized from a comb generated by molecular modulation.[[fileno]]2030165030076[[department]]電機工程學
Synthesis and Measurement of Subfemtosecond Optical Waveforms
No full text[[fileno]]2030165030078[[department]]電機工程學
Distributed real-time simulation and on-site development of a micro-grid with renewable energy sources
No full text[[abstract]]Micro-grid is a new concept gained significant attentions due to the increasing distributed energy sources. Several micro-grid test beds in the forms of either hardware or software simulation have been developed around the world. In Taiwan, one 20KVA 3W3Ø micro-grid test bed has been conducted in National Tsing Hua University (NTHU). This micro-grid consists of various fundamental power system components, including two synchronous generators (SG), one fixed speed induction generator (FSIG), and one doubly-fed induction generator (DFIG). In this paper, simulation results on two different scenarios: (a) transition from the grid-connected mode to the islanding mode, and (b) load variation in the islanding mode of the NTHU micro-grid system in distributed real-time simulation platform OPAL-RT are reported. Also, on-site development of the micro-grid system is illustrated.[[fileno]]2030140030048[[department]]電機工程學
A 32Gbps low propagation delay 4×4 switch IC for feedback-based system in 0.13μm CMOS technology
No full text[[abstract]]In this paper, a low propagation delay, low power, and area-efficient 4×4 load-balanced switch circuit for feedbackbased system is presented. In this periodic and deterministic switch, only two DFFs are used to implement a pattern generator which is a O(N3) hardware complexity in traditional matching algorithm based N×N switch. For packet reordering, a feedback path is established in series of symmetric patterns. As comparing with commercial switch systems, we implement a 4×4 switch IC directly in high speed domain without the use of SERDES interfaces to achieve low propagation delay and high scalability. In CML output buffer, PMOS active load and active back-end termination are introduced. A stacked current source and symmetric topology in CML-DFF are adopted. From our results, this work efficiently deducted 28ns propagation delay, 80% area and 80% power introduced by the SERDES interface. The throughput rate is up to 32Gbps (8Gbps/Ch).[[fileno]]2030122030057[[department]]電機工程學
Power Compensation Base on DIgital Predictive Current Controlled Three-Phase Bi-Directional Inverter with Wide Inductance Variation
No full text[[abstract]]This paper presents power compensation based on digital predictive current controlled three-phase bi-directional inverter with wide inductance variation. The three-phase bidirectional inverter can fulfill both real power and reactive power compensation for ac grid. With the proposed control, the inverter can track sinusoidal reference currents precisely with unity power factor or power factors -0.5 similar to +0.5, and it is allowed to have wide inductance variation, reducing core size significantly. In the design and implementation, the inductances corresponding to various inductor currents are measured and tabulated into a single-chip microcontroller for tuning loop gain cycle by cycle, ensuring system stability. Moreover, a one-phase shift detection method for anti-islanding operation based on the proposed control is also presented. Measured results from a 10 kVA 3 phi bi-directional inverter have confirmed the feasibility of the discussed control approach and detection method.[[fileno]]2030197030004[[department]]電機工程學
太陽能光電板之多模組最大功率追蹤器研製
No full text[[abstract]]本論文之目的為實作三組並聯之最大功率追蹤器，其基本結構為結合昇壓型(Boost)和降壓型(Buck)轉換器，而最大功率追蹤控制法則是使用擾動與觀察法，其控制方法簡單且容易實現。本論文首先介紹太陽光電系統、轉換原理、太陽光電池種類與特性以及最大功率追蹤控制法，接著介紹所採用的電路結構並說明動作原理，最後實際製作三組並聯之最大功率追蹤器(3.3 kW/set)來驗證此電路的可行性。經過測試結果得知其轉換效率最高可達98.8%，且最大功率點追蹤準確率(MPPT%)在98%以上，確實可以達到最大功率點追蹤功能。[[fileno]]2030197030017[[department]]電機工程學
單相雙向換流器系統之控制器週邊與通訊介面研製
No full text[[abstract]]本文介紹單相雙向換流器系統之控制器周邊與通訊介面的研究和製作，並應用於太陽能直流供電系統中。本研究以建構一智慧型電網為概念，使用雙控制器TMS320LF2406A建立雙向換流器系統之週邊與通訊介面，並選擇運用廣泛之SCI傳輸協定結合無線傳輸模組ZigBee、Bluetooth，實現遠端監控功能，以及使用SPI傳輸協定做為雙控制器間之通訊介面。文中除了闡述兩者之通訊原理及架構外，也進一步比較其差異。為了方便隨時能存取相關參數資料，使用EEPROM做為外部記憶體。此外也結合LCM，將最大功率追蹤器之動態資訊完整展現。最後，經由撰寫驅動程式，並與單相雙向換流器合併測試，以驗證本研究之可行性與正確性。[[fileno]]2030197030018[[department]]電機工程學
Current Ripple Analysis of Interleaved Critical-Mode Boost PFCs
No full text[[fileno]]2030197030040[[department]]電機工程學