目的探讨动态清零防控策略中新型冠状病毒全员核酸检测追踪隔离(citywide test-trace-isolation,CTTI)的最小轮次,为医疗资源的优化配置提供参考依据。方法利用微元法建模思想和二项分布性质,构建了估算CTTI最小轮次的单目标优化模型,...目的探讨动态清零防控策略中新型冠状病毒全员核酸检测追踪隔离(citywide test-trace-isolation,CTTI)的最小轮次,为医疗资源的优化配置提供参考依据。方法利用微元法建模思想和二项分布性质,构建了估算CTTI最小轮次的单目标优化模型,并进行实证评估和仿真模拟分析。结果最小轮次与核酸检测灵敏度和CTTI期间的隔离控制强度呈负相关,得到了能够达成动态清零目标的临界核酸检测灵敏度和CTTI期间隔离控制临界强度公式。本研究的模型模拟结果与2021年12月西安市Delta变异株疫情、2022年3月重庆市Omicron变异株疫情以及2022年1月深圳市“0131”Omicron变异株疫情演变都具有较好的一致性。仿真结果发现,CTTI期间的隔离控制强度对CTTI最小轮次的估计值影响最大,常态化防疫中发现首例本土感染者的时间与最终检出的感染者总数呈指数相关。结论为了降低疫情防控成本,优化卫生资源需求量,建议把CTTI策略调整为重点区域核酸检测追踪隔离(key areas test-trace-isolation,KTTI)策略。为了尽快达成动态清零目标,除了提高筛查精度和鼓励疫苗接种之外,CTTI或KTTI期间尤其需严格遵守防疫措施,最大限度减少病毒传播。展开更多
In order to eliminate the settlement underestimation in surcharge preload engineering, a study based on Bjerrum's creep diagram and the tangent slope definition of secondary consolidation coefficient was carried o...In order to eliminate the settlement underestimation in surcharge preload engineering, a study based on Bjerrum's creep diagram and the tangent slope definition of secondary consolidation coefficient was carried out to analyze the time effect of secondary consolidation coefficient of over consolidated soil, and a time–growth model for it was formulated. As Bjerrum's creep diagram is an idealized model, oedometer tests were performed to improve the above time–growth model of secondary consolidation coefficient for the purpose of achieving a better agreement with the actual ground situations. It is found that secondary consolidation coefficient of over consolidated soil not only decreases with the ratio of historical maximum to current effective stress of soil(OCR), but also increases with the development time of secondary consolidation. No matter how large OCR is, the long-term time effect of secondary consolidation coefficient of over consolidated soil is all significant. Based on the above results, a model for settlement estimation was formulated and a case study to estimate it indicates that the settlement estimated by our method is 2–5 times larger than that estimated by the previous method. Moreover, the larger the OCR is as well as the longer the service life is, the larger the difference between our method and the previous method is. Thus, the post-construction secondary settlement in surcharge preload engineering will be underestimated when neglecting the time effect of secondary consolidation coefficient in over consolidated state.展开更多
Multilinear commutators and iterated commutators of multilinear fractional integral operators with BMO functions are studied. Both strong type and weak type endpoint weighted estimates involving the multiple weights f...Multilinear commutators and iterated commutators of multilinear fractional integral operators with BMO functions are studied. Both strong type and weak type endpoint weighted estimates involving the multiple weights for such operators are established and the weak type endpoint results are sharp in some senses. In particular, we extend the results given by Cruz-Uribe and Fiorenza in 2003 and 2007 to the multilinear setting. Moreover, we modify the weak type of endpoint weighted estimates and improve the strong type of weighted norm inequalities on the multilinear commutators given by Chen and Xue in 2010 and 2011.展开更多
To use the 0th-order τ-ω model to retrieve soil moisture from radiometric data at frequencies higher than the C band, the characteristics of the effective single scattering albedo ω and the opacity rof vegetation m...To use the 0th-order τ-ω model to retrieve soil moisture from radiometric data at frequencies higher than the C band, the characteristics of the effective single scattering albedo ω and the opacity rof vegetation must be studied. In this paper, the co and r values of corn for the C, X, and Ku bands were retrieved by matching the simulations of a high-order matrix-doubling model to the τ-ω model. First, the brightness temperature of the matrix-doubling was validated by a truck-mounted radiometer in a field experiment, where the vegetation emission contributions were validated with aluminum foil to mask the soil emission. Then an emissivity database of corn fields for different growing seasons was established for a variety of soil conditions. With the transmissivity of corn determined from the database, the effective single scattering albedos of corn for different heights at the C, X, and Ku bands and at a 55° viewing angle were derived. To verify the accuracy of the derived co and τ values, we used SMEX02/PSR aircraft data and the Qp model to retrieve the soil moisture; the RMSE between the retrieval and the measurements was 4.76% at the C band and 5.36% at the X band.展开更多
We obtain the boundedness for the fractional integral operators from the modulation Hardy space μp,q to the modulation Hardy space μr,q for all 0 < p < ∞. The result is an extension of the known result for th...We obtain the boundedness for the fractional integral operators from the modulation Hardy space μp,q to the modulation Hardy space μr,q for all 0 < p < ∞. The result is an extension of the known result for the case 1 < p < ∞ and it contains a larger range of r than those in the classical result of the Lp → Lr boundedness in the Lebesgue spaces. We also obtain some estimates on the modulation spaces for the bilinear fractional operators.展开更多
文摘目的探讨动态清零防控策略中新型冠状病毒全员核酸检测追踪隔离(citywide test-trace-isolation,CTTI)的最小轮次,为医疗资源的优化配置提供参考依据。方法利用微元法建模思想和二项分布性质,构建了估算CTTI最小轮次的单目标优化模型,并进行实证评估和仿真模拟分析。结果最小轮次与核酸检测灵敏度和CTTI期间的隔离控制强度呈负相关,得到了能够达成动态清零目标的临界核酸检测灵敏度和CTTI期间隔离控制临界强度公式。本研究的模型模拟结果与2021年12月西安市Delta变异株疫情、2022年3月重庆市Omicron变异株疫情以及2022年1月深圳市“0131”Omicron变异株疫情演变都具有较好的一致性。仿真结果发现,CTTI期间的隔离控制强度对CTTI最小轮次的估计值影响最大,常态化防疫中发现首例本土感染者的时间与最终检出的感染者总数呈指数相关。结论为了降低疫情防控成本,优化卫生资源需求量,建议把CTTI策略调整为重点区域核酸检测追踪隔离(key areas test-trace-isolation,KTTI)策略。为了尽快达成动态清零目标,除了提高筛查精度和鼓励疫苗接种之外,CTTI或KTTI期间尤其需严格遵守防疫措施,最大限度减少病毒传播。
基金Project(51178419)supported by the National Natural Science Foundation of China
文摘In order to eliminate the settlement underestimation in surcharge preload engineering, a study based on Bjerrum's creep diagram and the tangent slope definition of secondary consolidation coefficient was carried out to analyze the time effect of secondary consolidation coefficient of over consolidated soil, and a time–growth model for it was formulated. As Bjerrum's creep diagram is an idealized model, oedometer tests were performed to improve the above time–growth model of secondary consolidation coefficient for the purpose of achieving a better agreement with the actual ground situations. It is found that secondary consolidation coefficient of over consolidated soil not only decreases with the ratio of historical maximum to current effective stress of soil(OCR), but also increases with the development time of secondary consolidation. No matter how large OCR is, the long-term time effect of secondary consolidation coefficient of over consolidated soil is all significant. Based on the above results, a model for settlement estimation was formulated and a case study to estimate it indicates that the settlement estimated by our method is 2–5 times larger than that estimated by the previous method. Moreover, the larger the OCR is as well as the longer the service life is, the larger the difference between our method and the previous method is. Thus, the post-construction secondary settlement in surcharge preload engineering will be underestimated when neglecting the time effect of secondary consolidation coefficient in over consolidated state.
基金National Natural Science Foundation of China (Grant No. 11071200)Natural Science Foundation of Fujian Province of China (Grant No. 2010J01013)
文摘Multilinear commutators and iterated commutators of multilinear fractional integral operators with BMO functions are studied. Both strong type and weak type endpoint weighted estimates involving the multiple weights for such operators are established and the weak type endpoint results are sharp in some senses. In particular, we extend the results given by Cruz-Uribe and Fiorenza in 2003 and 2007 to the multilinear setting. Moreover, we modify the weak type of endpoint weighted estimates and improve the strong type of weighted norm inequalities on the multilinear commutators given by Chen and Xue in 2010 and 2011.
基金supported by National Natural Science Foundations of China (Grant Nos. 41171266 and 41030534)
文摘To use the 0th-order τ-ω model to retrieve soil moisture from radiometric data at frequencies higher than the C band, the characteristics of the effective single scattering albedo ω and the opacity rof vegetation must be studied. In this paper, the co and r values of corn for the C, X, and Ku bands were retrieved by matching the simulations of a high-order matrix-doubling model to the τ-ω model. First, the brightness temperature of the matrix-doubling was validated by a truck-mounted radiometer in a field experiment, where the vegetation emission contributions were validated with aluminum foil to mask the soil emission. Then an emissivity database of corn fields for different growing seasons was established for a variety of soil conditions. With the transmissivity of corn determined from the database, the effective single scattering albedos of corn for different heights at the C, X, and Ku bands and at a 55° viewing angle were derived. To verify the accuracy of the derived co and τ values, we used SMEX02/PSR aircraft data and the Qp model to retrieve the soil moisture; the RMSE between the retrieval and the measurements was 4.76% at the C band and 5.36% at the X band.
基金supported by National Natural Science Foundation of China (Grant Nos.10931001, 10871173)
文摘We obtain the boundedness for the fractional integral operators from the modulation Hardy space μp,q to the modulation Hardy space μr,q for all 0 < p < ∞. The result is an extension of the known result for the case 1 < p < ∞ and it contains a larger range of r than those in the classical result of the Lp → Lr boundedness in the Lebesgue spaces. We also obtain some estimates on the modulation spaces for the bilinear fractional operators.
