Azimuthal electromagnetic(EM)logging while drilling(LWD)has been extensively used in high-angle and horizontal(HA/HZ)wells.However,due to the effects of formation anisotropy,accurate geosteering decision and formation...Azimuthal electromagnetic(EM)logging while drilling(LWD)has been extensively used in high-angle and horizontal(HA/HZ)wells.However,due to the effects of formation anisotropy,accurate geosteering decision and formation evaluations have become increasingly difficult.To quantitatively analyze the effect of anisotropy on tool responses and data processing,this paper investigates the sensitivity of EM LWD measurements to electric anisotropy and inversion accuracy via forward modeling and inversion.First,a sensitivity factor is defined to quantitatively analyze the sensitivity of the magnetic field components and synthetic signals to electric anisotropy.Then,azimuthal EM LWD responses in anisotropic layered formations are simulated,and the sensitivities to formation parameters for compensated and uncompensated tool configurations are comparatively analyzed.Finally,we discuss the effects of the inversion model on bed boundary inversion in anisotropic formations.Numerical simulation and inversion results show that azimuthal EM LWD can be significantly affected by electric anisotropy.Fortunately,by using a symmetrical compensation configuration,the sensitivity of the geosignals to electric anisotropy can be suppressed,and the boundary detection capability can be further enhanced.Anisotropy normally gives rise to separated resistivity curves and abnormal"horns";moreover,complicated nonlinear distortion can also arise in geosignals as the tool approaches a bed boundary.If anisotropy effects are ignored in the inversion process,the estimated bed boundary and formation resistivity are usually unreliable,which may mislead geosteering decisions.展开更多
In this paper a new method has been proposed to decide optimal placement and best sizing of STATCOM （static synchronous compensator）. The best place of STATCOM is found using the sensitivity analysis and optimum siz...In this paper a new method has been proposed to decide optimal placement and best sizing of STATCOM （static synchronous compensator）. The best place of STATCOM is found using the sensitivity analysis and optimum sizing of STATCOM is managed using the genetic algorithm. The average model can account for the high-frequency effects and power electronic losses, and more accurately predict the active and reactive power outputs of the STATCOM. This paper employs the DIgSILENT simulator and DPL （DIgSILENT programming language） as a programming tool of the DIgSILENT to show the validity of the proposed method. The effectiveness of suggested approach has been tested on part of the distribution network of Iran, Khoramdarreh city in Zanjan province.展开更多
David Julius利用辣椒辣素来识别皮肤神经末梢上对热/冷刺激做出反应的感受器,Ardem Patapoutian利用压力敏感细胞发现了一种对皮肤和内部器官的机械刺激作出反应的新型感受器。两位学者对感受器受体的分型、结构特点、作用及调控机制...David Julius利用辣椒辣素来识别皮肤神经末梢上对热/冷刺激做出反应的感受器,Ardem Patapoutian利用压力敏感细胞发现了一种对皮肤和内部器官的机械刺激作出反应的新型感受器。两位学者对感受器受体的分型、结构特点、作用及调控机制进行了深入的探讨,这使我们对热、冷、机械刺激以及疼痛的认识更为深入。展开更多
Many receptors,including thermal receptors and mechanical receptors,are only activated by stimuli within a clearly defined range of intensities.Differences in the receptive ranges enable individual receptors and their...Many receptors,including thermal receptors and mechanical receptors,are only activated by stimuli within a clearly defined range of intensities.Differences in the receptive ranges enable individual receptors and their sensory centers to precisely detect the intensity of the stimulus and changes in intensity.Baroreceptors are the sensory terminals of the baroreflex.It is well understood that an increasing number of baroreceptors are recruited to produce afferent action potentials as the blood pressure increases,indicating that individual baroreceptors have different pressure thresholds.The present study revealed that individual baroreceptors could stop their afferent signals when the blood pressure exceeds a certain level,indicating that individual baroreceptors are sensitive to a specific range of blood pressure.The receptive ranges of individual baroreceptors differ in terms of the total range,the lower threshold,and the upper threshold.Of 85 baroreceptors examined in this study,the upper thresholds for about half were within the physiological blood pressure range.These results indicate that supraphysiological blood pressure is unlikely to be encoded by the recruitment of more baroreceptors.Instead,supraphysiological blood pressure levels might be signaled by an increase in the frequency of action potentials or by other mechanisms.In conclusion,our results indicate that rabbit baroreceptors are activated by blood pressure levels within specific receptive ranges.These findings should encourage further studies to examine the role of population coding of blood pressure by baroreceptors in the baroreflex.展开更多
基金supported by the National Natural Science Foundation of China(No.41674131,No.41974146,and No.41904109)the Shandong Province Postdoctoral Innovation Projects(sdbh20180025)the Fundamental Research Funds for the Central Universities(No.17CX06041)。
文摘Azimuthal electromagnetic(EM)logging while drilling(LWD)has been extensively used in high-angle and horizontal(HA/HZ)wells.However,due to the effects of formation anisotropy,accurate geosteering decision and formation evaluations have become increasingly difficult.To quantitatively analyze the effect of anisotropy on tool responses and data processing,this paper investigates the sensitivity of EM LWD measurements to electric anisotropy and inversion accuracy via forward modeling and inversion.First,a sensitivity factor is defined to quantitatively analyze the sensitivity of the magnetic field components and synthetic signals to electric anisotropy.Then,azimuthal EM LWD responses in anisotropic layered formations are simulated,and the sensitivities to formation parameters for compensated and uncompensated tool configurations are comparatively analyzed.Finally,we discuss the effects of the inversion model on bed boundary inversion in anisotropic formations.Numerical simulation and inversion results show that azimuthal EM LWD can be significantly affected by electric anisotropy.Fortunately,by using a symmetrical compensation configuration,the sensitivity of the geosignals to electric anisotropy can be suppressed,and the boundary detection capability can be further enhanced.Anisotropy normally gives rise to separated resistivity curves and abnormal"horns";moreover,complicated nonlinear distortion can also arise in geosignals as the tool approaches a bed boundary.If anisotropy effects are ignored in the inversion process,the estimated bed boundary and formation resistivity are usually unreliable,which may mislead geosteering decisions.
文摘In this paper a new method has been proposed to decide optimal placement and best sizing of STATCOM （static synchronous compensator）. The best place of STATCOM is found using the sensitivity analysis and optimum sizing of STATCOM is managed using the genetic algorithm. The average model can account for the high-frequency effects and power electronic losses, and more accurately predict the active and reactive power outputs of the STATCOM. This paper employs the DIgSILENT simulator and DPL （DIgSILENT programming language） as a programming tool of the DIgSILENT to show the validity of the proposed method. The effectiveness of suggested approach has been tested on part of the distribution network of Iran, Khoramdarreh city in Zanjan province.
基金supported by the National Natural Science Foundation of China(30770701)the Fundamental Research Funds for the Central Universities(GK201302052,GK261001007)
文摘Many receptors,including thermal receptors and mechanical receptors,are only activated by stimuli within a clearly defined range of intensities.Differences in the receptive ranges enable individual receptors and their sensory centers to precisely detect the intensity of the stimulus and changes in intensity.Baroreceptors are the sensory terminals of the baroreflex.It is well understood that an increasing number of baroreceptors are recruited to produce afferent action potentials as the blood pressure increases,indicating that individual baroreceptors have different pressure thresholds.The present study revealed that individual baroreceptors could stop their afferent signals when the blood pressure exceeds a certain level,indicating that individual baroreceptors are sensitive to a specific range of blood pressure.The receptive ranges of individual baroreceptors differ in terms of the total range,the lower threshold,and the upper threshold.Of 85 baroreceptors examined in this study,the upper thresholds for about half were within the physiological blood pressure range.These results indicate that supraphysiological blood pressure is unlikely to be encoded by the recruitment of more baroreceptors.Instead,supraphysiological blood pressure levels might be signaled by an increase in the frequency of action potentials or by other mechanisms.In conclusion,our results indicate that rabbit baroreceptors are activated by blood pressure levels within specific receptive ranges.These findings should encourage further studies to examine the role of population coding of blood pressure by baroreceptors in the baroreflex.
