There are a lot of methods in city water consumption short-term forecasting both inside and outside the country. But among these methods there exist many advantages and shortcomings in model establishing, solving and ...There are a lot of methods in city water consumption short-term forecasting both inside and outside the country. But among these methods there exist many advantages and shortcomings in model establishing, solving and predicting accuracy, speed, applicability. This article draws lessons from other realm mature methods after many years′ study. It′s systematically studied and compared to predict the water consumption in accuracy, speed, effect and applicability among the time series triangle function method, artificial neural network method, gray system theories method, wavelet analytical method.展开更多
介绍了一种12 bit 60 MS/s流水线模数转换器(ADC),该转换器使用采样保持电路,将连续变化的模拟信号通过一定时间间隔的采样,以实现信号的准确量化,利用增益自举运放提高信号建立的线性度;采用每级1.5 bit精确度的流水线结构实现冗余编码...介绍了一种12 bit 60 MS/s流水线模数转换器(ADC),该转换器使用采样保持电路,将连续变化的模拟信号通过一定时间间隔的采样,以实现信号的准确量化,利用增益自举运放提高信号建立的线性度;采用每级1.5 bit精确度的流水线结构实现冗余编码,降低比较器失调电压对精确度的影响,同时提出一种新型的消除静态功耗的预放大比较器结构。该流水线ADC芯片采用华力55 nm互补金属氧化物(CMOS)工艺进行电路和版图设计。对后仿真结果进行快速傅里叶变换(FFT)分析得到:动态参数无杂散动态范围(SFDR)为86.18 d B,信噪比(SNR)为72.91 d B,信纳比(SNDR)为72.8 d B,有效位数(ENOB)为11.72 bit。展开更多
AIM: To systematically assess the efficacy and safety of β-adrenergic blocker plus 5-isosorbide mononitrate (BB + ISMN) and endoscopic band ligation (EBL) on prophylaxis of esophageal variceal rebleeding. METHODS: Ra...AIM: To systematically assess the efficacy and safety of β-adrenergic blocker plus 5-isosorbide mononitrate (BB + ISMN) and endoscopic band ligation (EBL) on prophylaxis of esophageal variceal rebleeding. METHODS: Randomized controlled trials (RCTs) comparing the efficacy and safety of BB + ISMN and EBL on prophylaxis of esophageal variceal rebleeding were gathered from Medline, Embase, Cochrane Controlled Trial Registry and China Biological Medicine database between January 1980 and August 2007. Data from five trials were extracted and pooled. The analyses of the available data using the Revman 4.2 software were based on the intention-to-treat principle. RESULTS: Four RCTs met the inclusion criteria. In comparison with BB + ISMN with EBL in prophylaxis of esophageal variceal rebleeding, there was no significant difference in the rate of rebleeding [relative risk (RR), 0.79; 95% CI: 0.62-1.00; P = 0.05], bleeding-related mortality (RR, 0.76; 95% CI: 0.31-1.42; P = 0.40), overall mortality (RR, 0.81; 95% CI: 0.61-1.08; P = 0.15) and complications (RR, 1.26; 95% CI: 0.93-1.70; P = 0.13). CONCLUSION:In the prevention of esophageal variceal rebleeding, BB + ISMN are as effective as EBL. There are few complications with the two treatment modalities. Both BB + ISMN and EBL would be considered as the first-line therapy in the prevention of esophageal variceal rebleeding.展开更多
Proximal point algorithms （PPA） are attractive methods for solving monotone variational inequalities （MVI）. Since solving the sub-problem exactly in each iteration is costly or sometimes impossible, various approx...Proximal point algorithms （PPA） are attractive methods for solving monotone variational inequalities （MVI）. Since solving the sub-problem exactly in each iteration is costly or sometimes impossible, various approximate versions ofPPA （APPA） are developed for practical applications. In this paper, we compare two APPA methods, both of which can be viewed as prediction-correction methods. The only difference is that they use different search directions in the correction-step. By extending the general forward-backward splitting methods, we obtain Algorithm Ⅰ; in the same way, Algorithm Ⅱ is proposed by spreading the general extra-gradient methods. Our analysis explains theoretically why Algorithm Ⅱ usually outperforms Algorithm Ⅰ. For computation practice, we consider a class of MVI with a special structure, and choose the extending Algorithm Ⅱ to implement, which is inspired by the idea of Gauss-Seidel iteration method making full use of information about the latest iteration. And in particular, self-adaptive techniques are adopted to adjust relevant parameters for faster convergence. Finally, some numerical experiments are reported on the separated MVI. Numerical results showed that the extending Algorithm II is feasible and easy to implement with relatively low computation load.展开更多
1 INTRODUCTION In the end of 1980＇s, an operational system for 3-D variation and assimilation of meteorological data was set up in the U.S.A that supplemented data assimilation, retrieval of satellite data and numeri...1 INTRODUCTION In the end of 1980＇s, an operational system for 3-D variation and assimilation of meteorological data was set up in the U.S.A that supplemented data assimilation, retrieval of satellite data and numerical prediction each other. NWP was thus improved. Towards the end of 1990＇s, satellite observations were extensively used in NWP at ECMWF to upgrade the quality of analysis and forecasting. Subsequently, Chinese meteorologists also made some studies on the analysis and assimilation of satellite data. Jiang et al. were the first to apply satellite imagery in numerical simulation of typhoon-inflicted heavy rain. Shen et al. and Min et al. conducted variational analysis and numerical simulation of conventional soundings and unconventional cloud imagery for limited areas and found that inclusion of cloud imagery could greatly improve rainfall forecast by the model. Zhu et al. suggested that the introduction of satellite-retrieved humidity field could better depict horizontal mesoscale structure of the real world. All of the studies above have achieved lots of meaningful results.展开更多
文摘There are a lot of methods in city water consumption short-term forecasting both inside and outside the country. But among these methods there exist many advantages and shortcomings in model establishing, solving and predicting accuracy, speed, applicability. This article draws lessons from other realm mature methods after many years′ study. It′s systematically studied and compared to predict the water consumption in accuracy, speed, effect and applicability among the time series triangle function method, artificial neural network method, gray system theories method, wavelet analytical method.
文摘介绍了一种12 bit 60 MS/s流水线模数转换器(ADC),该转换器使用采样保持电路,将连续变化的模拟信号通过一定时间间隔的采样,以实现信号的准确量化,利用增益自举运放提高信号建立的线性度;采用每级1.5 bit精确度的流水线结构实现冗余编码,降低比较器失调电压对精确度的影响,同时提出一种新型的消除静态功耗的预放大比较器结构。该流水线ADC芯片采用华力55 nm互补金属氧化物(CMOS)工艺进行电路和版图设计。对后仿真结果进行快速傅里叶变换(FFT)分析得到:动态参数无杂散动态范围(SFDR)为86.18 d B,信噪比(SNR)为72.91 d B,信纳比(SNDR)为72.8 d B,有效位数(ENOB)为11.72 bit。
文摘AIM: To systematically assess the efficacy and safety of β-adrenergic blocker plus 5-isosorbide mononitrate (BB + ISMN) and endoscopic band ligation (EBL) on prophylaxis of esophageal variceal rebleeding. METHODS: Randomized controlled trials (RCTs) comparing the efficacy and safety of BB + ISMN and EBL on prophylaxis of esophageal variceal rebleeding were gathered from Medline, Embase, Cochrane Controlled Trial Registry and China Biological Medicine database between January 1980 and August 2007. Data from five trials were extracted and pooled. The analyses of the available data using the Revman 4.2 software were based on the intention-to-treat principle. RESULTS: Four RCTs met the inclusion criteria. In comparison with BB + ISMN with EBL in prophylaxis of esophageal variceal rebleeding, there was no significant difference in the rate of rebleeding [relative risk (RR), 0.79; 95% CI: 0.62-1.00; P = 0.05], bleeding-related mortality (RR, 0.76; 95% CI: 0.31-1.42; P = 0.40), overall mortality (RR, 0.81; 95% CI: 0.61-1.08; P = 0.15) and complications (RR, 1.26; 95% CI: 0.93-1.70; P = 0.13). CONCLUSION:In the prevention of esophageal variceal rebleeding, BB + ISMN are as effective as EBL. There are few complications with the two treatment modalities. Both BB + ISMN and EBL would be considered as the first-line therapy in the prevention of esophageal variceal rebleeding.
基金Project (No. 1027054) supported by the National Natural Science Foundation of China
文摘Proximal point algorithms （PPA） are attractive methods for solving monotone variational inequalities （MVI）. Since solving the sub-problem exactly in each iteration is costly or sometimes impossible, various approximate versions ofPPA （APPA） are developed for practical applications. In this paper, we compare two APPA methods, both of which can be viewed as prediction-correction methods. The only difference is that they use different search directions in the correction-step. By extending the general forward-backward splitting methods, we obtain Algorithm Ⅰ; in the same way, Algorithm Ⅱ is proposed by spreading the general extra-gradient methods. Our analysis explains theoretically why Algorithm Ⅱ usually outperforms Algorithm Ⅰ. For computation practice, we consider a class of MVI with a special structure, and choose the extending Algorithm Ⅱ to implement, which is inspired by the idea of Gauss-Seidel iteration method making full use of information about the latest iteration. And in particular, self-adaptive techniques are adopted to adjust relevant parameters for faster convergence. Finally, some numerical experiments are reported on the separated MVI. Numerical results showed that the extending Algorithm II is feasible and easy to implement with relatively low computation load.
基金State Project for Key Fundamental Research Development Plan (2004CB418301)a project ofNational Natural Science Foundation of China (40075023)Key Technologies R&D Program of GuizhouProvince (20011145)
文摘1 INTRODUCTION In the end of 1980＇s, an operational system for 3-D variation and assimilation of meteorological data was set up in the U.S.A that supplemented data assimilation, retrieval of satellite data and numerical prediction each other. NWP was thus improved. Towards the end of 1990＇s, satellite observations were extensively used in NWP at ECMWF to upgrade the quality of analysis and forecasting. Subsequently, Chinese meteorologists also made some studies on the analysis and assimilation of satellite data. Jiang et al. were the first to apply satellite imagery in numerical simulation of typhoon-inflicted heavy rain. Shen et al. and Min et al. conducted variational analysis and numerical simulation of conventional soundings and unconventional cloud imagery for limited areas and found that inclusion of cloud imagery could greatly improve rainfall forecast by the model. Zhu et al. suggested that the introduction of satellite-retrieved humidity field could better depict horizontal mesoscale structure of the real world. All of the studies above have achieved lots of meaningful results.
