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Now showing items 129 - 144 of 207

  • Saturation of biphoton generation near atomic resonance

    Chen Peng   Qian Jun   Hu Zheng-Feng   Wang Yu-Zhu  

    We have numerically investigated the biphoton generation rate as a function of several parameters in the spontaneous four-wave mixing in cold atoms. It has been found that the biphoton generation rate can easily reach saturation with the intensity of the coupling laser increasing. The saturation intensity is mainly dependent on the dephasing rate of the ground states, unrelated to the pumping laser. It implies that though the biphoton waveform can be manipulated by the coupling laser, the generation rate of the biphoton cannot increase markedly after the saturation. The saturation effect also suggests that there is an optimal coupling laser for obtaining the largest biphoton generation rate with a sufficiently long coherence time.
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  • State Feedback Controller Design of Networked Control Systems with Parameter Uncertainty and State-delay

    Chen Peng   Dong Yue  

    This paper is concerned with the controller design of networked control systems. The continuous time plant with parameter uncertainty and state delay is studies. A new model of the networked control system is provided under consideration of the nonideal network conditions. In terms of the given model; a controller design method is proposed based on a delay dependent approach. The maximum allowable synthetical bounds related with the discarded data packet and network-included delay and the feedback gain of a memoryless controller can be derived by solving a set of linear matrix inequalities for the stabilizablity of the networked control system based on Lyapunov functional method. An example is given to show the effectiveness of our method.
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  • Comments on “The evidence of ‘CH01’ in sediment core samples of Pacific Ocean collected among FGGE” by Peng Han-Chang, Zhao Kui-Huan, and Chen Sui-Tian

    Glass, B. P.  

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  • Communication research methods - by Guoming Chen, Wenzheng Peng, Yinjiao Ye, and Ran An

    Wu, Peng; Feng, Jieyun  

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  • Network-based H∞ control of linear systems with state quantization

    Chen Peng   Yu-Chu Tian  

    This paper addresses H∞ controller design for linear systems over digital communication networks. An innovative model is proposed that describe both the network conditions and the state quantization of the networked control systems in an unified framework. From this model; a quantized state feedback strategy is developed for global and asymptotical stabilization of the networked control systems. The same H∞ disturbance attenuation level as in the case without quantization is achieved. Numerical examples are given to demonstrate the effectiveness of the proposed method.
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  • Comparative Study on Financial Calculation Indicators of PPP Project

    Xu Shunqing;Liu Shuangliu;Cheng Liang;Gao Jun;Chen Peng;Chinese Academy for Environmental Planning;  

    Financial calculation is an important part in the PPP project investment decision. In PPP practice, the selection of financial calculation indicators is quite arbitrary, which is prone to fairness imbalance between PPP projects to a certain extent and even affects project decisionmaking. Financial calculation indicators usually used in the PPP scheme design include financial internal rate of return, return on investment, reasonable profit rate, annual interest rate, etc. Based on the economic meanings of the four types of indicators and combined with specific cases, the study analyzes the quantitative relation and applicability between different indicators. When the PPP project involves as long a period as 20 to 30 years, it is recommended to use dynamic indicators(financial internal rate of return) rather than static indicators(return on investment,reasonable profit rate, annual interest rate) in the project investment decision. When dynamic indicators are selected, it is more suitable for the public sector to adopt the internal rate of return on investment without considering the financing cost and debt repayment. For private sector, the internal rate of return of the project capital reflects the profit after the financial leverage using equity fund, with more realistic reference significance.
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  • Event-Based Adaptive Fuzzy Tracking Control for High-Order Nonlinear Time-Delay Systems

    Jing-Wen Xing   Chen Peng  

    This paper investigates event-based adaptive fuzzy tracking control for high-order nonlinear time-delay systems. A novel power-integrator adaptive fuzzy tracking controller is constructed based event-triggering rules. Meanwhile, combining the backstepping design approach and a serial of transformations equipped with an improved integral Lyapunov function which guarantees the tracking error converges to a small neighborhood of the origin in probability. Finally, a simulation example is presented to illustrate the effectiveness of the control strategy.
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  • A new LS+AR model with additional error correction for polar motion forecast

    YAO YiBin   YUE ShunQiang   CHEN Peng  

    Polar motion depicts the slow changes in the locations of the poles due to the earth's internal instantaneous axis of rotation. The LS+AR model is recognized as one of the best models for polar motion prediction.Through statistical analysis of the time series of the LS+AR model's short-term prediction residuals,we found that there is a good correlation of model prediction residuals between adjacent terms.These indicate that the preceding model prediction residuals and experiential adjustment matrixes can be used to correct the next prediction results,thereby forming a new LS+AR model with additional error correction that applies to polar motion prediction.Simulated predictions using this new model revealed that the proposed method can improve the accuracy and reliability of polar motion prediction.In fact,the accuracies of ultra short-term and short-term predictions using the new model were equal to the international best level at present.
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  • Paper-based Vertical Flow Immunoassay (VFI) for detection of bio-threat pathogens

    Chen Peng   Gates-Hollingsworth Marcellene   Pandit Sujata   Park Anson   Montgomery Douglas   AuCoin David   Gu Jian   Zenhausern Frederic  

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  • High-Efficiency InGaN/GaN Nanorod Arrays by Temperature Dependent Photoluminescence

    Wang Wen-Jie   Chen Peng   Yu Zhi-Guo   Liu Bin   Xie Zi-Li   Xiu Xiang-Qian   Wu Zhen-Long   Xu Feng   Xu Zhou   Hua Xue-Mei   Zhao Hong   Han Ping   Shi Yi   Zhang Rong   Zheng You-Dou  

    We report on the photoluminescent characteristics of InGaN/GaN multiple quantum well (MQW) nanorod arrays with high internal quantum efficiency. The InGaN/GaN MQWs are grown by metalorganic chemical vapor deposition on c-plane sapphire substrates, and then the MQW nanorod arrays are fabricated by using inductively coupled plasma etching with self-assembled Ni nanoparticle mask with low-damage etching technique. The typical diameter of the nanorods is from 200nm to 300nm and the length is around 800 nm, which almost is dislocation free. At room temperature, an enhancement of 3.1 times in total integrated photoluminescence intensity is achieved from the MQW nanorod arrays, in comparison to that of the as-grown MQW structure. Based on the temperature-dependent photoluminescence measurements, the internal quantum efficiency of the nanorod structure is 59.2%, i.e., 1.75 times of as- grown MQW structure (33.8%). Therefore, the nanorod structure with a significant reduction of defects can be a very promising candidate for highly efficient light emitting devices.
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  • Carlos Fuentes Issue || Selected Poems of Ai Qingby Ai Qing; Eugene Chen Eoyang; Peng Wenlan; Marilyn Chin

    Review by: Robert E. Hegel  

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  • Comparative Analysis of Nutrient Composition of Caulerpa lentillifera from Different Regions

    ZHANG Meijian   MA Yurong   CHE Xinyi   HUANG Zumei   CHEN Peng   XIA Guanghua   ZHAO Meihui  

    This study investigated the difference of nutrient composition in Caulerpa lentillifera collected from different regions. The nutrient compositions of C. lentillifera from China's Hainan and Shandong provinces were determined and compared with those from Semporna(Malaysia), Sabah(Malaysia), Petchburi(Thailand), and two other species of seaweeds(Malaysia). The results showed that the polysaccharide and protein contents of C. lentillifera from Hainan(44.82% ± 0.98% and 12.5% ± 0.70%), Shandong(43.22% ± 1.42% and 14.7% ± 0.72%), Petchburi(59.27% ± 2.31% and 12.49% ± 0.30%), and Sabah(44.02% ± 2.01% and 19.38% ± 1.48%) were higher than those of Eucheuma cottonii(26.49% ± 3.01% and 9.76% ± 1.33%) and Sargassum polycystum(33.49% ± 1.70% and 5.40% ± 0.07%), respectively. The polyunsaturated fatty acid contents in C. lentillifera from Hainan(29.98%) and Shandong(22.11%) were higher than that in Semporna(16.76% ± 0.27%), Sabah(9.49%), and S. polycystum(20.34% ± 0.43%), but lower than that in E. cottonii(51.55% ± 0.57%). In Caulerpa lentillifera of Hainan and Shandong provinces, the essential amino acid(EAA)/total amino acid(TAA) ratios were 35.22% and 38.78%, respectively; and the EAA/ETAA ratios were 54.36% and 63.35%, respectively. The EAA composition of C. lentillifera was close to the ideal model of Food and Agriculture Organization/World Health Organization. C. lentillifera was rich in mineral elements, including calcium((3315.85 ± 127.55) mg(100 g)-1 and(3728.35 ± 92.38) mg(100 g)-1), magnesium((6715.74 ± 82.58) mg(100 g)-1 and(8128.59 ± 242.72) mg(100 g)-1), and trace elements, including iron((510.65 ± 5.47) mg(100 g)-1 and(1972.97 ± 183.35) mg(100 g)-1), selenium((1.04 ± 0.08) mg(100 g)-1 and(0.83 ± 0.15) mg(100 g)-1), and zinc((33.90 ± 0.13) mg(100 g)-1 and(11.75 ± 2.05) mg(100 g)-1). These results showed that C. lentillifera was more nutritious than S. polycystum or E. cottonii in terms of polysaccharide, protein, and fatty acid contents. Furthermore, both C. lentillifera species collected from Hainan and Shandong provinces show more basic nutrients. Therefore, C. lentillifera has important development and application prospects.
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  • Impacts of imperfect channel estimation and multipath fading on forward-link performance in CDMA distributed antenna systems

    Chen Peng   Wu Wei-ling  

    The study of performance in distributed antenna (DA) systems has recently received considerable attention and some conclusions have been drawn. However, most of them are based on the ideal channel estimation assumption and analyzed in flat fading channels. In this paper, we investigate the impact of imperfect channel estimation on the forward-link outage performance in CDMA DA systems in a multipath fading environment. A detailed analytical model, based on a hybrid signal combining method, is presented and an exact outage probability expression is derived. Our investigation shows that the effect of imperfect channel estimates varies with system load. Furthermore, we find that for the forward-link of DA systems, if simulcasting is employed, macrodiversity can decrease both the sensitivity of performance to channel estimation errors and the outage probability, which is contrary to the conclusion drawn based on the ideal channel estimation assumption.
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  • Low dose of hydroxychloroquine reduces fatality of critically ill patients with COVID-19

    Yu Bo   Li Chenze   Chen Peng   Zhou Ning   Wang Luyun   Li Jia   Jiang Hualiang   Wang Dao-Wen  

    Coronavirus disease 2019 (COVID-19) is a pandemic with no specific drugs and high fatality. The most urgent need is to find effective treatments. We sought to determine whether hydroxychloroquine (HCQ) application may reduce the death risk of critically ill COVID-19 patients. In this retrospective study, we included 550 critically ill COVID-19 patients who need mechanical ventilation in Tongji Hospital, Wuhan, from February 1, 2020 to April 4, 2020. All 550 patients received comparable basic treatments including antiviral drugs and antibiotics, and 48 of them were treated with oral HCQ treatment (200 mg twice a day for 7-10 days) in addition to the basic treatments. Primary endpoint is fatality of patients, and inflammatory cytokine levels were compared between HCQ and non-hydroxychloroquine (NHCQ) treatments. We found that fatalities are 18.8% (9/48) in HCQ group, which is significantly lower than 47.4% (238/502) in the NHCQ group (P<0.001). The time of hospital stay before patient death is 15 (10-21) days and 8 (4-14) days for the HCQ and NHCQ groups, respectively (P<0.05). The levels of inflammatory cytokine IL-6 were significantly reduced from 22.2 (8.3-118.9) pg mL(-1) at the beginning of the treatment to 5.2 (3.0-23.4) pg mL(-1) (P<0.05) at the end of the treatment in the HCQ group but there is no change in the NHCQ group. These data demonstrate that addition of HCQ on top of the basic treatments is highly effective in reducing the fatality of critically ill patients of COVID-19 through attenuation of inflammatory cytokine storm. Therefore, HCQ should be prescribed as a part of treatment for critically ill COVID-19 patients, with possible outcome of saving lives. hydroxychloroquine, IL-6, mortalities, COVID-19
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  • A fast 32 K×8 CMOS static RAM with address transition detection: C W Chen, J P Peng, M Y S Shyu, M Amundson, J C Yu (Adv. Micro Devices Inc., Sunnyvale, CA, USA) IEEE J. Solid-State Circuits (USA) vol. SC-22, no. 4, pp. 533–537 (Aug. 1987)

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  • Building energy use in China: Ceiling and scenario

    Chen Peng   Da Yan   Siyue Guo   Shan Hu   Yi Jiang  

    Highlights • Energy use has a ceiling for the limitation of energy supply and requirement of CO 2 emission reduction. • In order to keep the stable economy and social development, building energy use should be no more than 1 billion tce. • China building energy use can be divided into four sub-sectors based on the current situation. • It is necessary to control the energy use intensity to achieve the target of total energy control. Abstract With increasing levels of urbanization and a growing economy, total building energy use in China is rapidly increasing. However, energy use must be controlled due to limited energy supply and the goal of lowering carbon emissions. This study tried to define a reasonable limit for total energy use in China, and, more specifically, a target for building energy use. Domestic energy production, energy imports, and the need to reduce CO 2 emissions and fossil fuel combustion were considered when analyzing the available energy for China. The current status and future trends of energy use by industry, building, and transportation sectors were analyzed to determine how much energy the building sector can use considering economic growth and improving living conditions. Within the framework of “Ecological civilization,” this study suggests that annual building energy use in China has to be limited to no more than 1 billion tce.
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