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Now showing items 1 - 16 of 98

  • Light-emitting diode chip packages and methods for manufacture thereof

    A light-emitting diode chip package and a manufacturing process thereof sequentially includes a transparent layer, a fluorescent layer, a wafer layer, a light-emitting diode chip, a dielectric layer, a metal circuit layer, and a protective film and conductive blocks used to draw out the electrodes of the light-emitting diode chip. The outer surfaces of the fluorescent layer and the wafer layer retreat from the fluorescent layer down to the wafer layer to form a slant, and the dielectric layer, the metal circuit layer, and the protective film spread out to coat the slant. Simple techniques at low cost are involved.
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  • Method and server system for synchronization of audio/video media files

    A method for synchronization of audio/video (AV) media files includes: writing respectively AV real-time transport protocol (RTP) packets and AV real-time transport control protocol (RTCP) packets into AV buffers; obtaining respectively timestamps in first ones of AV RTCP packets to serve as absolute start times of first ones of the AV RTP packets, and AV timestamp differences between the timestamps of adjacent ones of the AV RTP packets; generating respectively playback timestamps of the AV RTP packets according to the AV timestamp differences in combination with the absolute start times; and writing the AV RTP packets in combination with the playback timestamps of the AV RTP packets into a media file.
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  • Price impact asymmetry of institutional trading in Chinese stock market

    Fei Ren   Li-Xin Zhong  

    The asymmetric price impact between the institutional purchases and sales of 32 liquid stocks inC hinese stock markets in year 2003 is carefully studied. We analyze the price impact in both drawup and drawdown trends with consecutive positive and negative daily price changes, and test the dependence of the price impact asymmetry on the market condition. For most of the stocks institutional sales have a larger price impact than institutional purchases, and larger impact of institutional purchases only exists in few stocks with primarily increasing tendencies. We further study the mean return of trades surrounding institutional transactions, and find the asymmetric behavior also exists before and after institutional transactions. A new variable is proposed to investigate the order book structure, and it can partially explain the price impact of institutional transactions. A linear regression for the price impact of institutional transactions further confirms our finding that institutional sales primarily have a larger price impact than institutional purchases in the bearish year 2003.
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  • Catalyst containing a modified Y-type zeolite and a preparation process thereof

    The present invention discloses a catalytic cracking catalyst and a preparation process therefor. The catalytic cracking catalyst comprises a cracking active component, 10 wt %-70 wt % of a clay on the dry basis, and 10 wt %-40 wt % of an inorganic oxide binder (as oxide), relative to the weight of the catalytic cracking catalyst, wherein said cracking active component contains, relative to the weight of the catalytic cracking catalyst, 10 wt %-50 wt % of a modified Y-type zeolite on the dry basis and 0-40 wt % of other zeolite on the dry basis, wherein said modified Y-type zeolite is characterized by having a unit cell size of 2.420-2.440 nm; as percent by weight of the modified Y-type zeolite, a phosphorus content of 0.05-6%, a RE2O3 content of 0.03-10%, and an alumina content of less than 22%; and a specific hydroxy nest concentration of less than 0.35 mmol/g and more than 0.05 mmol/g.
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  • Fractographic study of epoxy under mode I and mixed mode I/III loading

    Fei Ren   John Jy-An Wang   Williams D. Bertelsen  

    Fiber-reinforced polymeric matrix composites are widely used in structural components such as wind turbine blades, which are typically subject to complicated loading conditions. Thus, the response of these materials under mixed-mode loading is of great relevance to the reliability of these structures. In this study, a novel fracture testing methodology, the spiral notch torsion test (SNTT), was applied to study the fracture behavior of an epoxy resin. SNTT samples were tested using either monotonic loading or cyclic loading, while both mode I and mixed mode I/III loading conditions were used. Fractographic examination indicated the epoxy samples prevalently failed in mode I even when the test specimens were subject to mixed mode loading. Different fatigue precracks were observed on mode I and mixed mode samples, i.e. precracks appeared as a uniform band under mode I loading, and a semi-ellipse under mixed mode loading. Fracture toughness was also estimated using quantitative fractography. [All rights reserved Elsevier].
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  • Scaling and memory in the return intervals of realized volatility

    Fei Ren   Gao-Feng Gu   Wei-Xing Zhou  

    We perform return interval analysis of 1-min realized volatility dened by the sum of absolute high-frequency intraday returns for the Shanghai Stock Exchange Composite Index (SSEC) and 22 constituent stocks of SSEC. The scaling behavior and memory effect of the return intervals between successive realized volatilities above a certain threshold q are carefully investigated. In comparison with the volatility dened by the closest tick prices to the minute marks, the return interval distribution for the realized volatility shows a better scaling behavior since 20 stocks (out of 22 stocks) and the SSEC pass the Kolmogorov-Smirnov(KS) test and exhibit scaling behaviors, among which the scaling function for 8 stocks could be approximated well by a stretched exponential distribution revealed by the KS goodness- of-t test under the signicance level of 5%. The improved scaling behavior is further conrmed by the relation between the tted exponent and the threshold q. In addition, the similarity of the return interval distributions for different stocks is also observed for the realized volatility. The investigation of the conditional probability distribution and the detrended uctuation analysis (DFA) show that both short-term and long-term memory exists in the return intervals of realized volatility.
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  • Empirical regularities of opening call auction in Chinese stock market

    Gao-Feng Gu   Fei Ren   Xiao-Hui Ni  

    We study the statistical regularities of opening call auction using the ultra-high-frequency data of 22 liquid stocks traded on the Shenzhen Stock Exchange in 2003. The distribution of the relative price, dened as the relative difference between the order price in opening call auction and the closing price of last trading day, is asymmetric and that the distribution displays a sharp peak at zero relative price and a relatively wide peak at negative relative price. The detrended uctuation analysis (DFA) method is adopted to investigate the long-term memory of relative order prices. We further study the statistical regularities of order sizes in opening call auction, and observe a phenomenon of number preference, known as order size clustering. The probability density function (PDF) of order sizes could be well tted by a q-Gamma function, and the long-term memory also exists in order sizes. In addition, both the average volume and the average number of orders decrease exponentially with the price level away from the best bid or ask price level in the limit-order book (LOB) established immediately after the opening call auction, and a price clustering phenomenon is observed.
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  • Engineering the K+ uptake regulatory pathway by MultiRound Gateway

    Fei Ren   Qi-Jun Chen   Min Xie   Li-Juan Li   Wei-Hua Wu   Jia Chen   Xue-Chen Wang  

    In a previous study, we described improved versions of MultiRound Gateway vectors. Here, we engineered a calcineurin B-like (CBL) pathway for potassium (K+) nutrition to demonstrate their effectiveness. Using the two improved entry vectors pL12R34H-Ap and pL34R12-Cm, and through 2–4 rounds of Gateway recombination reactions, we generated five pMDC99-derived binary vectors [pK21 (CIPK23 + CBL1), pK29 (CIPK23 + CBL9), pK31 (CIPK23 + CBL1 + AKT1), pK39 (CIPK23 + CBL9 + AKT1), and pK4 (CIPK23 + CBL1 + AKT1 + CBL9)], in which all four genes have the same pSuper promoter and tNos terminator. pK31, pK39 and pK4 were transformed into Arabidopsis. PCR analysis confirmed that all transgenes usually co-existed in the K31, K39 or K4 transgenic plants, and qRT-PCR analysis indicated that the transgenes were expressed at reasonably high levels. The eight overexpression lines, except K31-1, displayed significantly tolerant phenotypes to low-K+ and low-K+ combined with low-Ca2+ compared to the wild type. Significant differences between the K31, K39 and K4 lines were not observed. These results indicate that the improved MultiRound Gateway vectors efficiently assembled multiple transgenes, which were stably inherited and expressed in transformed plants, even with the same promoter and terminator.
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  • Scaling and memory in the return intervals of realized volatility

    Fei Ren   Gao-Feng Gu   Wei-Xing Zhou  

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  • Engineering the K+ uptake regulatory pathway by MultiRound Gateway

    Fei Ren   Qi-Jun Chen   Min Xie   Li-Juan Li   Wei-Hua Wu   Jia Chen   Xue-Chen Wang  

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  • Statistical properties of volatility return intervals of Chinese stocks

    Fei Ren   Liang Guo   Wei-Xing Zhou  

    The statistical properties of the return intervals τq between successive 1-min volatilities of 30 liquid Chinese stocks exceeding a certain threshold q are carefully studied. The Kolmogorov–Smirnov (KS) test shows that 12 stocks exhibit scaling behaviors in the distributions of τq for different thresholds q. Furthermore, the KS test and weighted KS test show that the scaled return interval distributions of 6 stocks (out of the 12 stocks) can be nicely fitted by a stretched exponential function with γ≈0.31 under the significance level of 5%, where is the mean return interval. The investigation of the conditional probability distribution Pq(ττ0) and the mean conditional return interval ττ0 demonstrates the existence of short-term correlation between successive return interval intervals. We further study the mean return interval ττ0 after a cluster of n intervals and the fluctuation F(l) using detrended fluctuation analysis, and find that long-term memory also exists in the volatility return intervals.
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  • Statistical properties of volatility return intervals of Chinese stocks

    Fei Ren   Liang Guo   Wei-Xing Zhou  

    The statistical properties of the return intervals τq between successive 1-min volatilities of 30 liquid Chinese stocks exceeding a certain threshold q are carefully studied. The Kolmogorov–Smirnov (KS) test shows that 12 stocks exhibit scaling behaviors in the distributions of τq for different thresholds q. Furthermore, the KS test and weighted KS test show that the scaled return interval distributions of 6 stocks (out of the 12 stocks) can be nicely fitted by a stretched exponential function with γ≈0.31 under the significance level of 5%, where is the mean return interval. The investigation of the conditional probability distribution Pq(ττ0) and the mean conditional return interval ττ0 demonstrates the existence of short-term correlation between successive return interval intervals. We further study the mean return interval ττ0 after a cluster of n intervals and the fluctuation F(l) using detrended fluctuation analysis, and find that long-term memory also exists in the volatility return intervals.
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  • Cavitation-based hydro-fracturing technique for geothermal reservoir stimulation

    A rotary shutter valve 500 is used for geothermal reservoir stimulation. The valve 500 includes a pressure chamber 520 for holding a working fluid (F) under pressure. A rotatable shutter 532 is turned with a powering device 544 to periodically align one or more windows 534 with one or more apertures 526 in a bulkhead 524. When aligned, the pressurized working fluid (F) flows through the bulkhead 524 and enters a pulse cavity 522, where it is discharged from the pulse cavity 522 as pressure waves 200. The pressure wave propagation 200 and eventual collapse of the bubbles 202 can be transmitted to a target rock surface 204 either in the form of a shock wave 206, or by micro jets 208, depending on the bubble-surface distance. Once cavitation at the rock face begins, fractures are initiated in the rock to create a network of micro-fissures for enhanced heat transfer.
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  • Alternative approach for cavitation damage study utilizing repetitive laser pulses

    Fei Ren   John Jy-An Wang   Hong Wang  

    Cavitation is a common phenomenon in fluid systems that can lead to dramatic degradation of solid materials surface in contact with the cavitating media. Study of cavitation damage has great significance in many engineering fields. Current techniques for cavitation damage study either require large scale equipments or tend to introduce damages from other mechanisms. In this project, we utilized the cavitation phenomenon induced by laser optical breakdown and developed a prototype apparatus for cavitation damage study. In our approach, cavitation was generated by the repetitive pressure waves induced by high-power laser pulses. As proof of principal study, stainless steel and aluminum samples were tested using the novel apparatus. Surface characterization via scanning electron microscopy revealed damages such as indentation and surface pitting, which were similar to those reported in the literature using other state-of-the-art techniques. These preliminary results demonstrated the new device was capable of generating cavitation damages and could be used as an alternative method for cavitation damage study. [All rights reserved Elsevier].
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  • Alternative approach for cavitation damage study utilizing repetitive laser pulses

    Fei Ren   John Jy-An Wang   Hong Wang  

    Cavitation is a common phenomenon in fluid systems that can lead to dramatic degradation of solid materials surface in contact with the cavitating media. Study of cavitation damage has great significance in many engineering fields. Current techniques for cavitation damage study either require large scale equipments or tend to introduce damages from other mechanisms. In this project, we utilized the cavitation phenomenon induced by laser optical breakdown and developed a prototype apparatus for cavitation damage study. In our approach, cavitation was generated by the repetitive pressure waves induced by high-power laser pulses. As proof of principal study, stainless steel and aluminum samples were tested using the novel apparatus. Surface characterization via scanning electron microscopy revealed damages such as indentation and surface pitting, which were similar to those reported in the literature using other state-of-the-art techniques. These preliminary results demonstrated the new device was capable of generating cavitation damages and could be used as an alternative method for cavitation damage study.
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  • Multiscaling behavior in the volatility return intervals of Chinese indices

    Fei Ren   Wei-Xing Zhou  

    We investigate the probability distribution of the return intervals between successive 1-min volatilities of two Chinese indices exceeding a certain threshold q. The Kolmogorov-Smirnov (KS) tests show that the two in- dices exhibit multiscaling behavior in the distribution of , which follows a stretched exponential form fq( / ) e a( / ) with different correlation exponent for different threshold q, where is the mean return interval cor- responding to a certain value of q. An extended self-similarity analysis of the moments provides further evidence of multiscaling in the return intervals.
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