The structural changes brought about by shale oil revolution have inspired this paper of which the aim is to analyze the potential asymmetries related to the determinants of crude oil production in the USA.Thus,using ...The structural changes brought about by shale oil revolution have inspired this paper of which the aim is to analyze the potential asymmetries related to the determinants of crude oil production in the USA.Thus,using a Markov-switching dynamic regression model in which parameters change when oil production moves from one regime to the other,it is found that for both oil production and oil relative importance,the regime that was dominant during the 1980s and the early 1990s when oil production in the USA was substantially high is the same regime that has once again become dominant in the decade corresponding to the shale oil revolution.Furthermore,the study reveals the existence of asymmetries in the relationship between US crude oil production and both manufacturing production and the consumer price index.Asymmetries are also found in the relationship between the relative importance US crude oil and manufacturing production.Finally,it is found that the intercept and the variance parameter also vary from one regime to the other,thus justifying the use of regime-dependent models.展开更多
A column-switching anion-exchange chromatography method was described for the separation and determination of petroleum monosulfonates （PMS） and petroleum disulfonates （PDS） in crude oil that was simply diluted wi...A column-switching anion-exchange chromatography method was described for the separation and determination of petroleum monosulfonates （PMS） and petroleum disulfonates （PDS） in crude oil that was simply diluted with the dichloromethane/methanol （60/40）. The high performance liquid chromatography （HPLC） system consisted of a clean-up column and an analytical column, which were connected with two six-port switching valves. Detection of petroleum sulfonates was available and repeatable. This method has been successfully applied to determine PMS and PDS in crude oil samples from Shengli oil field.展开更多
Water content in output crude oil is hard to measure precisely because of wide range of dielectric coefficient of crude oil caused by injected dehydrating and demulsifying agents.The method to reduce measurement error...Water content in output crude oil is hard to measure precisely because of wide range of dielectric coefficient of crude oil caused by injected dehydrating and demulsifying agents.The method to reduce measurement error of water content in crude oil proposed in this paper is based on switching measuring ranges of on-line water content analyzer automatically.Measuring precision on data collected from oil field and analyzed by in-field operators can be impressively improved by using back propogation （BP） neural network to predict water content in output crude oil.Application results show that the difficulty in accurately measuring water-oil content ratio can be solved effectively through this combination of on-line measuring range automatic switching and real time prediction,as this method has been tested repeatedly on-site in oil fields with satisfactory prediction results.展开更多
This paper proposes a Markov-switching copula model to examine the presence of regime change in the time-varying dependence structure between oil price changes and stock market returns in six GCC countries. The margin...This paper proposes a Markov-switching copula model to examine the presence of regime change in the time-varying dependence structure between oil price changes and stock market returns in six GCC countries. The marginal distributions are assumed to follow a long-memory model while the copula parameters are supposed to evolve according to the Markov-switching process. Furthermore, we estimate the Value-at-Risk (VaR) based on the proposed approach. The empirical results provide evidence of three regime changes, representing precrisis, financial crisis and post-crisis, in the dependence structure between energy and GCC stock markets. In particular, in the pre- and post-crisis regimes, there is no dependence, while in the crisis regime, there is significant tail dependence. For OPEC countries, we find lower tail dependence whereas in non-OPEC countries, we see upper tail dependence. VaR experiments show that the Markov-switching time- varying copula model performs better than the time-varying copula model.展开更多
Background: Managing hypertriglyceridemia in HIV-infected patients often requires multiple pharmacologic strategies. Many protease inhibitors (PIs), one of 6 classes of drugs used to treat HIV, have been associated wi...Background: Managing hypertriglyceridemia in HIV-infected patients often requires multiple pharmacologic strategies. Many protease inhibitors (PIs), one of 6 classes of drugs used to treat HIV, have been associated with hypercholesterolemia and drug interactions. For this study, we examined a dual strategy to manage hypertriglyceridemia in HIV-infected patient taking PIs: 1) switching patients to fosamprenavir (FPV), a PI with fewer drug interactions, and 2) adding prescription fish oil (LOVAZA?), which has been shown to reduce triglycerides. Methods: This multicenter, 24-week study enrolled 36 patients virologically suppressed (HIV-1 RNA <50 copies/mL) on PI-containing therapy with screening triglyceride levels of 200 - 1200 mg/dL and LDL cholesterol levels ≤160 mg/dL. At baseline, patients were switched to ritonavir (RTV)-boosted fosamprenavir (FPV 1400 mg/RTV 100 mg QD) and any lipid-lowering agents were stopped. At Week 6, LOVAZA 4 g QD was added. Results: Five patients prematurely discontinued due to adverse events (2), non-compliance, lost-to-follow up, and protocol violation. Median triglyceride concentration was 303 mg/dL at screening, 262 mg/dL at baseline, 290 mg/dL at Week 6 (+8% from baseline), and 218 mg/dL at Week 24 (–30% from Week 6). At Week 24, 39% (12/31) of patients had triglycerides <200 mg/dL. Among patients reaching Week 24, 100% (31/31) and 90% (28/31) had HIV-1 RNA <400 and <50 copies/mL, respectively. Conclusions: In this study, a switch to FPV/RTV followed by LOVAZA decreased median triglyceride levels and modestly increased the percentage of patients with triglyceride levels <200 mg/dL while maintaining virologic suppression in HIV-infected subjects with hypertriglyceridemia. Our data suggest that baseline PI may affect the likelihood of achieving triglycerides <200 mg/dL after 18 weeks on study. A larger study would be needed to understand the relative contributions of choice of protease inhibitor and LOVAZA to triglyceride concentrations in HIV-infected patients.展开更多
A well-documented finding is that explicitly using jumps cannot efficiently enhance the predictability of crude oil price volatility.To address this issue,we find a phenomenon,“momentum of jumps”(MoJ),that the predi...A well-documented finding is that explicitly using jumps cannot efficiently enhance the predictability of crude oil price volatility.To address this issue,we find a phenomenon,“momentum of jumps”(MoJ),that the predictive ability of the jump component is persistent when forecasting the oil futures market volatility.Specifically,we propose a strategy that allows the predictive model to switch between a benchmark model without jumps and an alternative model with a jump component according to their recent past forecasting performance.The volatility data are based on the intraday prices of West Texas Intermediate.Our results indicate that this simple strategy significantly outperforms the individual models and a series of competing strategies such as forecast combinations and shrinkage methods.A mean–variance investor who targets a constant Sharpe ratio can realize the highest economic gains using the MoJ-based volatility forecasts.Our findings survive a wide variety of robustness tests,including different jump measures,alternative volatility measures,various financial markets,and extensive model specifications.展开更多
空管系统为全国民用航空提供空中交通服务、通信导航监视、航空气象、航行情报服务,是民航运行的枢纽。供电设备故障会严重影响空中交通安全。为确保设备的供电安全,从航管小区供配电系统设计出发,提出基于双市电双油机供电、不间断电源...空管系统为全国民用航空提供空中交通服务、通信导航监视、航空气象、航行情报服务,是民航运行的枢纽。供电设备故障会严重影响空中交通安全。为确保设备的供电安全,从航管小区供配电系统设计出发,提出基于双市电双油机供电、不间断电源(Uninterruptible Power Supply,UPS)并机双路供电、分布式静态转换开关(Static Transfer Switch,STS)供电以及直流应急供电的多重冗余供电体系。在空管设备末端供电设计方面,针对设备结构和管制席位设备及功能,提出优化的冗余供电设计方案。展开更多
文摘The structural changes brought about by shale oil revolution have inspired this paper of which the aim is to analyze the potential asymmetries related to the determinants of crude oil production in the USA.Thus,using a Markov-switching dynamic regression model in which parameters change when oil production moves from one regime to the other,it is found that for both oil production and oil relative importance,the regime that was dominant during the 1980s and the early 1990s when oil production in the USA was substantially high is the same regime that has once again become dominant in the decade corresponding to the shale oil revolution.Furthermore,the study reveals the existence of asymmetries in the relationship between US crude oil production and both manufacturing production and the consumer price index.Asymmetries are also found in the relationship between the relative importance US crude oil and manufacturing production.Finally,it is found that the intercept and the variance parameter also vary from one regime to the other,thus justifying the use of regime-dependent models.
基金the National Nature Science Foundation of China(No.20675085)the support from the Program of the Light in China's Western Region(2003)the Province Nature Science Foundation of Gansu(No.3ZS041-A25-23).
文摘A column-switching anion-exchange chromatography method was described for the separation and determination of petroleum monosulfonates （PMS） and petroleum disulfonates （PDS） in crude oil that was simply diluted with the dichloromethane/methanol （60/40）. The high performance liquid chromatography （HPLC） system consisted of a clean-up column and an analytical column, which were connected with two six-port switching valves. Detection of petroleum sulfonates was available and repeatable. This method has been successfully applied to determine PMS and PDS in crude oil samples from Shengli oil field.
基金Sponsored by the Basic Research Fundation of Beijing Institute of Technology (200705422009)
文摘Water content in output crude oil is hard to measure precisely because of wide range of dielectric coefficient of crude oil caused by injected dehydrating and demulsifying agents.The method to reduce measurement error of water content in crude oil proposed in this paper is based on switching measuring ranges of on-line water content analyzer automatically.Measuring precision on data collected from oil field and analyzed by in-field operators can be impressively improved by using back propogation （BP） neural network to predict water content in output crude oil.Application results show that the difficulty in accurately measuring water-oil content ratio can be solved effectively through this combination of on-line measuring range automatic switching and real time prediction,as this method has been tested repeatedly on-site in oil fields with satisfactory prediction results.
文摘This paper proposes a Markov-switching copula model to examine the presence of regime change in the time-varying dependence structure between oil price changes and stock market returns in six GCC countries. The marginal distributions are assumed to follow a long-memory model while the copula parameters are supposed to evolve according to the Markov-switching process. Furthermore, we estimate the Value-at-Risk (VaR) based on the proposed approach. The empirical results provide evidence of three regime changes, representing precrisis, financial crisis and post-crisis, in the dependence structure between energy and GCC stock markets. In particular, in the pre- and post-crisis regimes, there is no dependence, while in the crisis regime, there is significant tail dependence. For OPEC countries, we find lower tail dependence whereas in non-OPEC countries, we see upper tail dependence. VaR experiments show that the Markov-switching time- varying copula model performs better than the time-varying copula model.
文摘Background: Managing hypertriglyceridemia in HIV-infected patients often requires multiple pharmacologic strategies. Many protease inhibitors (PIs), one of 6 classes of drugs used to treat HIV, have been associated with hypercholesterolemia and drug interactions. For this study, we examined a dual strategy to manage hypertriglyceridemia in HIV-infected patient taking PIs: 1) switching patients to fosamprenavir (FPV), a PI with fewer drug interactions, and 2) adding prescription fish oil (LOVAZA?), which has been shown to reduce triglycerides. Methods: This multicenter, 24-week study enrolled 36 patients virologically suppressed (HIV-1 RNA <50 copies/mL) on PI-containing therapy with screening triglyceride levels of 200 - 1200 mg/dL and LDL cholesterol levels ≤160 mg/dL. At baseline, patients were switched to ritonavir (RTV)-boosted fosamprenavir (FPV 1400 mg/RTV 100 mg QD) and any lipid-lowering agents were stopped. At Week 6, LOVAZA 4 g QD was added. Results: Five patients prematurely discontinued due to adverse events (2), non-compliance, lost-to-follow up, and protocol violation. Median triglyceride concentration was 303 mg/dL at screening, 262 mg/dL at baseline, 290 mg/dL at Week 6 (+8% from baseline), and 218 mg/dL at Week 24 (–30% from Week 6). At Week 24, 39% (12/31) of patients had triglycerides <200 mg/dL. Among patients reaching Week 24, 100% (31/31) and 90% (28/31) had HIV-1 RNA <400 and <50 copies/mL, respectively. Conclusions: In this study, a switch to FPV/RTV followed by LOVAZA decreased median triglyceride levels and modestly increased the percentage of patients with triglyceride levels <200 mg/dL while maintaining virologic suppression in HIV-infected subjects with hypertriglyceridemia. Our data suggest that baseline PI may affect the likelihood of achieving triglycerides <200 mg/dL after 18 weeks on study. A larger study would be needed to understand the relative contributions of choice of protease inhibitor and LOVAZA to triglyceride concentrations in HIV-infected patients.
基金Yaojie Zhang acknowledges the financial support from the National Natural Science Foundation of China(72001110)the Fundamental Research Funds for the Central Universities(30919013232)+4 种基金the Research Fund for Young Teachers of School of Economics and Management,NJUST(JGQN2009)Yudong Wang acknowledges the financial support from the National Natural Science Foundation of China(72071114)Feng Ma acknowledges the support from the National Natural Science Foundation of China(71701170,72071162)Yu Wei acknowledges the support from the National Natural Science Foundation of China(71671145,71971191)Science and technology innovation team of Yunnan provincial.
文摘A well-documented finding is that explicitly using jumps cannot efficiently enhance the predictability of crude oil price volatility.To address this issue,we find a phenomenon,“momentum of jumps”(MoJ),that the predictive ability of the jump component is persistent when forecasting the oil futures market volatility.Specifically,we propose a strategy that allows the predictive model to switch between a benchmark model without jumps and an alternative model with a jump component according to their recent past forecasting performance.The volatility data are based on the intraday prices of West Texas Intermediate.Our results indicate that this simple strategy significantly outperforms the individual models and a series of competing strategies such as forecast combinations and shrinkage methods.A mean–variance investor who targets a constant Sharpe ratio can realize the highest economic gains using the MoJ-based volatility forecasts.Our findings survive a wide variety of robustness tests,including different jump measures,alternative volatility measures,various financial markets,and extensive model specifications.
文摘空管系统为全国民用航空提供空中交通服务、通信导航监视、航空气象、航行情报服务,是民航运行的枢纽。供电设备故障会严重影响空中交通安全。为确保设备的供电安全,从航管小区供配电系统设计出发,提出基于双市电双油机供电、不间断电源(Uninterruptible Power Supply,UPS)并机双路供电、分布式静态转换开关(Static Transfer Switch,STS)供电以及直流应急供电的多重冗余供电体系。在空管设备末端供电设计方面,针对设备结构和管制席位设备及功能,提出优化的冗余供电设计方案。
