17,243 research outputs found
Control and Filtering for Discrete Linear Repetitive Processes with H infty and ell 2--ell infty Performance
No full textRepetitive processes are characterized by a series of sweeps, termed passes, through a set of dynamics defined over a finite duration known as the pass length. On each pass an output, termed the pass profile, is produced which acts as a forcing function on, and hence contributes to, the dynamics of the next pass profile. This can lead to oscillations which increase in amplitude in the pass to pass direction and cannot be controlled by standard control laws. Here we give new results on the design of physically based control laws for the sub-class of so-called discrete linear repetitive processes which arise in applications areas such as iterative learning control. The main contribution is to show how control law design can be undertaken within the framework of a general robust filtering problem with guaranteed levels of performance. In particular, we develop algorithms for the design of an H? and dynamic output feedback controller and filter which guarantees that the resulting controlled (filtering error) process, respectively, is stable along the pass and has prescribed disturbance attenuation performance as measured by and – norms
Remaking History: The Shu and Wu Perspectives in the Three Kingdoms Period
No full textOf the three powers—Wei, Shu, and Wu—that divided China for the better part of the third century, Wei has received the most attention in the standard literary historical accounts. In a typical book of Chinese literary history in any language, little, if anything, is said about Wu and Shu. This article argues that the consideration of the literary production of Shu and Wu is crucial to a fuller picture of the cultural dynamics of the Three Kingdoms period. The three states competed with one another for the claim to political legitimacy and cultural supremacy, and Wu in particular was in a position to contend with Wei in its cultural undertakings, notably in the areas of history writing and ritual music. This article begins with an overview of Shu and Wu literary production, and moves on to a more detailed discussion of Wu's cultural projects, both of which were intended to assert Wu's legitimacy and cultural power vis-à-vis Wei and Shu's claims to cultural and political orthodoxy. Ultimately, this article implicitly asks the question of how to write literary history when there is scant material from the period under question, and suggests that we perform textual excavations and make use of what we have to try and reconstruct, as best as we can, what once was. A good literary history of the Chinese medieval period, the age of manuscript culture and that of heavy textual losses and transfigurations, should be written with the awareness of the incomplete and imperfect nature of the data we do have, and incorporate the phenomenon of textual losses and transfigurations as well as some reflections on the underlying reasons into its narrative and critical inquiry.East Asian Languages and CivilizationsVersion of Recor
Acoustic radiation due to scattering of T-S wave by the mean-flow distortion induced by steady local suction
No full textSubstantial sound waves can be generated by boundary-layer instability modes when the latter are scattered by a rapid mean-flow distortion. This is a rather generic mechanism and operates when an oncoming T-S wave is scattered by a steady local suction slot. This paper focuses on this problem by extending a recently developed Local Scattering Theory (Wu & Dong, J. Fluid Mech. submitted), where a so-called transmission coefficient, defined as the ratio of the T-S wave amplitude downstream of the scatter to that upstream, is introduced to characterize the effect of a local scatter on boundary-layer instability and transition. As in the earlier work, the mathematical formulation is based on triple-deck formulism, but in order to accommodate the acoustic far field, which was not considered in the paper mentioned, the unsteady terms in the upper deck, which play a leading-order role in radiation, are retained, and the influence of the radiated sound on the near-wall perturbation is included. The upper deck equation for the pressure is the Helmholtz equation rather than the Laplace equation. This leads to a modified pressure-displacement relation, which is coupled with the linearized boundary-layer equations in the lower deck. Discretization of the whole system formulates a generalized eigenvalue problem, which is solved numerically. It is found that suction suppresses oncoming T-S waves, and this effect increases with the suction velocity and the slot width. The directivity is ndependent of the flow parameters only when the Mach number is low. The intensity of the radiated sound in general increases with the frequency, the suction velocity and the width of the suction slot. Interestingly, for O(1) suction velocities, the radiated sound is very weak, indicating that the gain of stabilizing effect does not cause aeroacoustic penalty
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Tim Wu & “The Curse of Bigness”
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Business Model, Open Innovation, and Sustainability in Car Sharing Industry—Comparing Three Economies
Get PDFThis paper discusses dynamics and differences of business models in the car-sharing industry and focuses on open innovation as the trigger of diverse business models among Uber in the U.S., DiDi Chuxing in China, and KakaoT in Korea. We seek to answer the following two questions: What creates the differences in the business models of the car-sharing industry? Do the differences in open innovation motivate the diversity of business models among Uber, DiDi Chuxing, and KakaoT? We incorporated participatory observation, interviews, and semi-structured questionnaire methods in our study. We used two-step participatory observation and interview methods, hence carrying out observation and interviews two times by different researchers with Uber drivers in the U.S., DiDi-Chuxing drivers in Beijing, and KakaoT taxi drivers in Korea to confirm the interview and participatory observation results. First, business models of the car-sharing firms Uber, DiDi-Chuxing, and KakaoT are not fixed but rather are dynamically changing. Second, business models of car-sharing firms are the result of interaction with government regulations, the taxi industry, public transportation, and the automotive car industry. Third, open innovation strategies of car-sharing firms determine the contents and dynamics of car-sharing business models, such as the revenue business model, responsibility business model, and system business model upon interaction with four agencies
An ultra-low-power RF transceiver for WBANs in medical applications
No full textA2.4 GHz ultra-low-power RF transceiver with a900 MHz auxiliary wake-up link for wireless body area networks(WBANs) in medical applications is presented. The RF transceiver with an asymmetric architecture is proposed to achieve high energy efficiency according to the asymmetric communication in WBANs. The transceiver consists of a main receiver(RX) with an ultra-low-power free-running ring oscillator and a high speed main transmitter(TX) with fast lock-in PLL. A passive wake-up receiver(WuRx) for wake-up function with a high power conversion efficiency(PCE) CMOS rectifier is designed to offer the sensor node the capability of work-on-demand with zero standby power. The chip is implemented in a0.18μm CMOS process. Its core area is1.6 mm2. The main RX achieves a sensitivity of-55 dBm at a100 kbps OOK data rate while consuming just210μA current from the1 V power supply. The main TX achieves+3 dBm output power with a4 Mbps/500 kbps/200 kbps data rate for OOK/4 FSK/2 FSK modulation and dissipates3.25 mA/6.5 mA/6.5 mA current from a1.8 V power supply. The minimum detectable RF input energy for the wake-up RX is-15 dBm and the PCE is more than25%.?2011 Chinese Institute of Electronics
online_Supplementary – Supplemental material for Personalized risk prediction of symptomatic intracerebral hemorrhage after stroke thrombolysis using a machine-learning model
No full textSupplemental material, online_Supplementary for Personalized risk prediction of symptomatic intracerebral hemorrhage after stroke thrombolysis using a machine-learning model by Feng Wang, Yuanhanqing Huang, Yong Xia, Wei Zhang, Kun Fang, Xiaoyu Zhou, Xiaofei Yu, Xin Cheng, Gang Li, Xiaoping Wang, Guojun Luo, Danhong Wu, Xueyuan Liu, Bruce C.V. Campbell, Qiang Dong and Yuwu Zhao in Therapeutic Advances in Neurological Disorders</p
Measurement of dwell times of spin polarized rubidium atoms on octadecyltrichlorosilane- and paraffin-coated surfaces
No full textWe report the measurement of dwell times of spin polarized Rb atoms on octadecyltrichlorosilane OTS- and paraffin-coated surfaces. We find that at a cell temperature of 72 °C the dwell times for OTS- and paraffin-coated surfaces are 0.9+-0.1 microsecond and 1.8 +-0.2 microsecond , respectively. Since the relaxation probability on paraffin is almost one order of magnitude smaller than that on OTS, the longer dwell time for paraffin indicates that the average strength of the interactions experienced by Rb atoms while they are inside paraffin is much weaker than while they are inside OTS.Peer reviewe
A fast-settling frequency-presetting PLL frequency synthesizer with process variation compensation and spur reduction
No full textThis paper proposes a fast-settling frequency-presetting PLL frequency synthesizer. A mixed-signal VCO and a digital processor are developed to accurately preset the frequency of VCO and greatly reduce the settling time. An auxiliary tuning loop is introduced in order to reduce reference spur caused by leakage current. The digital processor can automatically compensate presetting frequency variation with process and temperature, and control the operation of the auxiliary tuning loop. A 1.2 GHz integer-N synthesizer with 1 MHz reference input Was implemented in a 0.18μm process. The measured results demonstrate that the typical settling time of the synthesizer is less than 3μs,and the phase noise is -108 dBc/[email protected] reference spur is -52 dBc
[[alternative]]A Study on History of Shin-Wu Elementary School at Tao-Yuan（1905-2003）
No full text[[abstract]]To explore the school cultural development in Shin-Wu Elementary school in the last hundred years and the significance of school history research in educational history, this study examines documents and files in the school history room of Shin-Wu Elementary school and has oral history interviews as well. The main findings of this study are as follows.
1. In late Meiji, most of the teachers were Japanese or Taiwanese from the nearby common schools, however, the turnover was high. At that time, only affluent students attended schools while later, more students were from poor families. Yet, the drop-out rate was relatively high.
2. As for the age, most students went to school in their teens, for they had to share responsibilities in home chores.
3. In Taisyo period, there were more and more teachers who had been Shin-Wu graduates and students were from different sources.
4. Owing to the air raid during the war, schools got closed very often and the content of education was mainly about laboring.
5. Post-war education, compared with that before, varied little in educational contents and forms because of the position-retaining teachers and staff.
6. For the last hundred years, nearly one-third of Shin-Wu teachers were their graduates and principals and teachers of branch schools came form Shin-Wu Elementary School, too. Therefore, Shin-Wu Elementary School had played an influential role in the elementary education and the local people cultivation in Shin-Wu area.
7. Shin-Wu Elementary School had always followed the national educational policy, seldom did they have local standpoints, which meant, they had to strengthen their autonomy and capacity when faced with new challenges especially after the lifting of Martial Law.
8. Through elaborative school cultural analysis, relationship among education, politics, economy and society, in particular, individual area development will be more carefully investigated.
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