In this note, the author introduces some new subcIasses of starlike mappings S^＊Ωn1p2,…,pn（β,A,B）={f∈H（Ω）：｜itanβ＋（1-itanβ）2/p（z）аp/аz（z）Jf^-1（z）f（z）-1-AB/1-B^2｜〈B-A/1-B^2},on Reinhardt dom...In this note, the author introduces some new subcIasses of starlike mappings S^＊Ωn1p2,…,pn（β,A,B）={f∈H（Ω）：｜itanβ＋（1-itanβ）2/p（z）аp/аz（z）Jf^-1（z）f（z）-1-AB/1-B^2｜〈B-A/1-B^2},on Reinhardt domains Ωn1p2,…,pn=z∈C^n：｜z1｜^2＋n∑j=2｜zj｜^pj〈1}where - 1≤A〈B〈1,q=min{p2,…,pn}≥1,l=max{p2,…,pn}≥2 and β ∈（-π/2,π/2）.Some different conditions for P are established such that these classes are preserved under the following modified Roper-Suffridge operator F（z）=（f（z1）＋f＇（z1）Pm（z0）,（f＇（z1））^1/mz0）＇where f is a normalized biholomorphic function on the unit disc D, z = （z1,z0） ∈Ωn1p2,…,pn,z0=（z2,…,zn）∈ C^n-1.Another condition for P is also obtained such that the above generalized Roper-Suffridge operator preserves an almost spirallike function of type/3 and order β These results generalize the modified Roper-Suffridge extension oper-ator from the unit ball to Reinhardt domains. Notice that when p2 = p3 …=pn = 2,our results reduce to the recent results of Feng and Yu.展开更多
The principle of single to single phase matrix electric power conversioin is further studied and the conversioin switch function is introduced into conventional rectifier inverter, thus a general character of the t...The principle of single to single phase matrix electric power conversioin is further studied and the conversioin switch function is introduced into conventional rectifier inverter, thus a general character of the two conversion techniques is discovered. It is characteristic of the switch functiion to follow mains voltage distortion and mains frequency drift. By utilizing the merit, unidirectional switch duty rations of the inverter follow the variation of DC link voltage automatically, thus the size of DC link electrolytic capacitor can be reduced considerably, bringing about improved mains side power factor. Corresponding topologies and theoretical and theoretical derivations are given, and so are the simulation results, based on which it is confirmed that the single to single phase matrix conversion technique is potentially useful in large scale production, and the introduction of switch function can yield good economic returns.展开更多
Using a limit process, it is proved in this paper that the adjoint matrix of an idempotent matrix is idempotent and the adjoint matrix of a nilpotent matrix is also nilpotent. The results are richer than that in [1].
Water distribution networks are essential components of water supply systems. The combination of pipe structural deterioration and mechanics leads to the failure of pipelines. A physical model for estimating the pipe ...Water distribution networks are essential components of water supply systems. The combination of pipe structural deterioration and mechanics leads to the failure of pipelines. A physical model for estimating the pipe failure must include both the pipe deterioration model and mechanics model. Winkler pipe-soil interaction (WPSI), an analytical mechanics model developed by Rajani and Tesfamariam (2004), takes external and internal loads, temperature changes, loss of bedding support, and the elastoplastic effect of soil into consideration. Based on the WPSI model, a method to evaluate the elastic and plastic areas was proposed in the present study. An FEM model based on pipe-soil interaction (PSI) element was used to verify the analytical model. Sensitivity analyses indicate that the soft soil, long pipe and high temperature induced the axial plastic deformation more likely, which, however, may not occur in normal scenarios. The soft soil, pipes in small diameters, long unsupported bedding are prone to form flexural plastic area. The results show that the pipes subjected to the same loads have smaller stresses in the elastoplastic analysis than elastic analysis. The difference, however, is slight.展开更多
Field investigations of several gas mains in different geosystems were carried out in Noviy Urengoy region (Eastern Siberia) in September, 2003. There were on ground pipelines covered with peat or sand. In case of sma...Field investigations of several gas mains in different geosystems were carried out in Noviy Urengoy region (Eastern Siberia) in September, 2003. There were on ground pipelines covered with peat or sand. In case of small rivers pipelines were elevated by pile support on the shores. Because pipelines were applied in cryolithozone that means special secure methods used in pipeline systems functioning and operating. There are multiple sites of natural landscapes destructed or totally destroyed during building and exploiting of the pipelines. That causes negative cryogenic processes development. The most dangerous one is the heaving, that reaches up to several meters in humid landscapes. The complex thermoerosion, thermokarst and heaving occur very often at one site. The heaving of piles leads to pipe deformations and the emergency situations to occur. It is possible to predict negative cryogenic processes development and so far to reduce an emergency risk.展开更多
This study aimed to explore the disinfection of drinking water in trunk water mains, based on published conditions denoted within the Irish Republic. The variables within the study were consumer draw-off rates, trunk ...This study aimed to explore the disinfection of drinking water in trunk water mains, based on published conditions denoted within the Irish Republic. The variables within the study were consumer draw-off rates, trunk main length, pipe diameter, and water temperature. All these factors are known to impact the free chlorine residual in operational supply networks. Based on published conditions obtained within the literature review, 60 hypothetical trunk mains were generated for this study. Of primary concern were the variables that affect the chlorine decay rate;total amount of chlorine decay;available amount of chlorine in the periphery of the trunk main;and the costs associated with effective chlorine disinfection of trunk mains. Based on the analysis performed, the following were the salient observations: 1) Low consumer draw-off rates and increased trunk main length and diameter increased the risk of the free chlorine residual in the periphery of the trunk mains not complying with the Environmental Protection Agency’s (EPA) minimum recommended residual value of 0.1 mg/l (EPA Drinking Water Audit Report, 2014). 2) Increasing the diameter of the trunk main from 125 mm to 180 mm had a negligible effect on the chlorine decay rate. However, increasing the trunk main diameter from 125 mm to 180 mm was shown to have a major impact on the total amount of chlorine decay and free chlorine residual available in the periphery of the main. The key parameters that affected disinfection costs associated with trunk mains include length, diameter and the need for chlorine boosting.展开更多
In this article, we borrow the idea of using Schur＇s test to characterize the compactness of composition operators on the weighted Bergman spaces in a bounded symmetricdomain Ω and verify that Cφ is compact on Lqa...In this article, we borrow the idea of using Schur＇s test to characterize the compactness of composition operators on the weighted Bergman spaces in a bounded symmetricdomain Ω and verify that Cφ is compact on Lqa（Ω,dvβ）if and only if K（φ（z）,φ（z））/K（z,z）→0 as z→ Ω under a mild condition,where K（z,w）is the Bergman kernel.展开更多
备自投装置可以提高供电的可靠性,因此,其在220 k V电力系统中得到了广泛的应用。但由于备自投动作逻辑复杂,而且具有不稳定性,造成备自投在实际运用中出现不能正确动作,导致失压设备未能及时恢复供电的事故。通过实际案例对备自投进行...备自投装置可以提高供电的可靠性,因此,其在220 k V电力系统中得到了广泛的应用。但由于备自投动作逻辑复杂,而且具有不稳定性,造成备自投在实际运用中出现不能正确动作,导致失压设备未能及时恢复供电的事故。通过实际案例对备自投进行分析,并对200 k V备自投的应用提出了一些建议,以确保备自投装置动作的可靠性。展开更多
In order to ensure power system stability, modern wind turbines are required to be able to endure deep voltage dips. The specifications that determine the voltage dip versus time are called fault r/de-through （FRT） ...In order to ensure power system stability, modern wind turbines are required to be able to endure deep voltage dips. The specifications that determine the voltage dip versus time are called fault r/de-through （FRT） requirements. The purpose of this paper is not only to examine the FRT behavior of a full-power converter wind turbine but also to combine the power system viewpoint to the studies. It is not enough for the turbine to be FRT capable; the loss of mains （LOM） protection of the turbine must also be set to allow the FRT. Enabling FRT, however, means that the LOM protection settings must be loosen, which may sometimes pose a safety hazard. This article introduces unique real-time simulation environment and proposes an FRT method for a wind turbine that also takes the operation of LOM protection relay into account. Simulations are carried out using the simulation environment and results show that wind turbine is able to ride-through a symmetrical power system fault.展开更多
It is known that homogeneous bounded domains are holomorphic isomorphic to N-Siegel domains, in order to compute the holomorphic sectional curvatures of the homogeneous bounded domains, one needs only to compute the h...It is known that homogeneous bounded domains are holomorphic isomorphic to N-Siegel domains, in order to compute the holomorphic sectional curvatures of the homogeneous bounded domains, one needs only to compute the holomorphic展开更多
A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous...A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous reactive power theory based algorithm was unsatisfactory in terms of isolating positive sequence fundamental active components exactly under non-ideal mains voltages. So, a modified ip-iq reference current calculation method was presented. With usage of the new method, not only the positive sequence but also the fundamental active current components can be accurately isolated from load current. A deadbeat closed-loop control model is built in order to eliminate both delay error and tracking error between reference voltages and compensation voltages under unbalanced and distorted mains voltages. Computer simulation results show that the proposed strategy is effective with better tracking ability and lower total harmonic distortion (THD). The strategy is also applied to a 10 kV substation with a local electrolysis manganese plant injecting a large amount of harmonics into the power system, and is proved to be more practical and efficient.展开更多
基金supported by the National Natural Science Foundation of China(11001246,11101139)Zhejiang Innovation Project(T200905)
文摘In this note, the author introduces some new subcIasses of starlike mappings S^＊Ωn1p2,…,pn（β,A,B）={f∈H（Ω）：｜itanβ＋（1-itanβ）2/p（z）аp/аz（z）Jf^-1（z）f（z）-1-AB/1-B^2｜〈B-A/1-B^2},on Reinhardt domains Ωn1p2,…,pn=z∈C^n：｜z1｜^2＋n∑j=2｜zj｜^pj〈1}where - 1≤A〈B〈1,q=min{p2,…,pn}≥1,l=max{p2,…,pn}≥2 and β ∈（-π/2,π/2）.Some different conditions for P are established such that these classes are preserved under the following modified Roper-Suffridge operator F（z）=（f（z1）＋f＇（z1）Pm（z0）,（f＇（z1））^1/mz0）＇where f is a normalized biholomorphic function on the unit disc D, z = （z1,z0） ∈Ωn1p2,…,pn,z0=（z2,…,zn）∈ C^n-1.Another condition for P is also obtained such that the above generalized Roper-Suffridge operator preserves an almost spirallike function of type/3 and order β These results generalize the modified Roper-Suffridge extension oper-ator from the unit ball to Reinhardt domains. Notice that when p2 = p3 …=pn = 2,our results reduce to the recent results of Feng and Yu.
文摘The principle of single to single phase matrix electric power conversioin is further studied and the conversioin switch function is introduced into conventional rectifier inverter, thus a general character of the two conversion techniques is discovered. It is characteristic of the switch functiion to follow mains voltage distortion and mains frequency drift. By utilizing the merit, unidirectional switch duty rations of the inverter follow the variation of DC link voltage automatically, thus the size of DC link electrolytic capacitor can be reduced considerably, bringing about improved mains side power factor. Corresponding topologies and theoretical and theoretical derivations are given, and so are the simulation results, based on which it is confirmed that the single to single phase matrix conversion technique is potentially useful in large scale production, and the introduction of switch function can yield good economic returns.
文摘Using a limit process, it is proved in this paper that the adjoint matrix of an idempotent matrix is idempotent and the adjoint matrix of a nilpotent matrix is also nilpotent. The results are richer than that in [1].
基金Project supported by the National Natural Science Foundation of China (No. 50278088)the Program for New Century Excellent Talents in University (No. NCET-04-0525), China
文摘Water distribution networks are essential components of water supply systems. The combination of pipe structural deterioration and mechanics leads to the failure of pipelines. A physical model for estimating the pipe failure must include both the pipe deterioration model and mechanics model. Winkler pipe-soil interaction (WPSI), an analytical mechanics model developed by Rajani and Tesfamariam (2004), takes external and internal loads, temperature changes, loss of bedding support, and the elastoplastic effect of soil into consideration. Based on the WPSI model, a method to evaluate the elastic and plastic areas was proposed in the present study. An FEM model based on pipe-soil interaction (PSI) element was used to verify the analytical model. Sensitivity analyses indicate that the soft soil, long pipe and high temperature induced the axial plastic deformation more likely, which, however, may not occur in normal scenarios. The soft soil, pipes in small diameters, long unsupported bedding are prone to form flexural plastic area. The results show that the pipes subjected to the same loads have smaller stresses in the elastoplastic analysis than elastic analysis. The difference, however, is slight.
文摘Field investigations of several gas mains in different geosystems were carried out in Noviy Urengoy region (Eastern Siberia) in September, 2003. There were on ground pipelines covered with peat or sand. In case of small rivers pipelines were elevated by pile support on the shores. Because pipelines were applied in cryolithozone that means special secure methods used in pipeline systems functioning and operating. There are multiple sites of natural landscapes destructed or totally destroyed during building and exploiting of the pipelines. That causes negative cryogenic processes development. The most dangerous one is the heaving, that reaches up to several meters in humid landscapes. The complex thermoerosion, thermokarst and heaving occur very often at one site. The heaving of piles leads to pipe deformations and the emergency situations to occur. It is possible to predict negative cryogenic processes development and so far to reduce an emergency risk.
文摘This study aimed to explore the disinfection of drinking water in trunk water mains, based on published conditions denoted within the Irish Republic. The variables within the study were consumer draw-off rates, trunk main length, pipe diameter, and water temperature. All these factors are known to impact the free chlorine residual in operational supply networks. Based on published conditions obtained within the literature review, 60 hypothetical trunk mains were generated for this study. Of primary concern were the variables that affect the chlorine decay rate;total amount of chlorine decay;available amount of chlorine in the periphery of the trunk main;and the costs associated with effective chlorine disinfection of trunk mains. Based on the analysis performed, the following were the salient observations: 1) Low consumer draw-off rates and increased trunk main length and diameter increased the risk of the free chlorine residual in the periphery of the trunk mains not complying with the Environmental Protection Agency’s (EPA) minimum recommended residual value of 0.1 mg/l (EPA Drinking Water Audit Report, 2014). 2) Increasing the diameter of the trunk main from 125 mm to 180 mm had a negligible effect on the chlorine decay rate. However, increasing the trunk main diameter from 125 mm to 180 mm was shown to have a major impact on the total amount of chlorine decay and free chlorine residual available in the periphery of the main. The key parameters that affected disinfection costs associated with trunk mains include length, diameter and the need for chlorine boosting.
基金Supported by the National Natural Science Foundation of China (10771064)Natural Science Foundation of Zhejiang Province (Y7080197, Y6090036, Y6100219)+1 种基金Foundation of Creative Group in Colleges and Universities of Zhejiang Province (T200924)Foundation of Department of Education of Zhejiang province (20070482)
文摘In this article, we borrow the idea of using Schur＇s test to characterize the compactness of composition operators on the weighted Bergman spaces in a bounded symmetricdomain Ω and verify that Cφ is compact on Lqa（Ω,dvβ）if and only if K（φ（z）,φ（z））/K（z,z）→0 as z→ Ω under a mild condition,where K（z,w）is the Bergman kernel.
文摘备自投装置可以提高供电的可靠性,因此,其在220 k V电力系统中得到了广泛的应用。但由于备自投动作逻辑复杂,而且具有不稳定性,造成备自投在实际运用中出现不能正确动作,导致失压设备未能及时恢复供电的事故。通过实际案例对备自投进行分析,并对200 k V备自投的应用提出了一些建议,以确保备自投装置动作的可靠性。
文摘In order to ensure power system stability, modern wind turbines are required to be able to endure deep voltage dips. The specifications that determine the voltage dip versus time are called fault r/de-through （FRT） requirements. The purpose of this paper is not only to examine the FRT behavior of a full-power converter wind turbine but also to combine the power system viewpoint to the studies. It is not enough for the turbine to be FRT capable; the loss of mains （LOM） protection of the turbine must also be set to allow the FRT. Enabling FRT, however, means that the LOM protection settings must be loosen, which may sometimes pose a safety hazard. This article introduces unique real-time simulation environment and proposes an FRT method for a wind turbine that also takes the operation of LOM protection relay into account. Simulations are carried out using the simulation environment and results show that wind turbine is able to ride-through a symmetrical power system fault.
文摘It is known that homogeneous bounded domains are holomorphic isomorphic to N-Siegel domains, in order to compute the holomorphic sectional curvatures of the homogeneous bounded domains, one needs only to compute the holomorphic
基金Project(JC200903180555A) supported by Shenzhen City Science and Technology Plan, China
文摘A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous reactive power theory based algorithm was unsatisfactory in terms of isolating positive sequence fundamental active components exactly under non-ideal mains voltages. So, a modified ip-iq reference current calculation method was presented. With usage of the new method, not only the positive sequence but also the fundamental active current components can be accurately isolated from load current. A deadbeat closed-loop control model is built in order to eliminate both delay error and tracking error between reference voltages and compensation voltages under unbalanced and distorted mains voltages. Computer simulation results show that the proposed strategy is effective with better tracking ability and lower total harmonic distortion (THD). The strategy is also applied to a 10 kV substation with a local electrolysis manganese plant injecting a large amount of harmonics into the power system, and is proved to be more practical and efficient.
