To predict the segregation effect in metal injection moulding (MIM) injection, a bi-phasic model based on mixture theory is adopted in simulation. An explicit algorithm is developed and realized by the authors, which ...To predict the segregation effect in metal injection moulding (MIM) injection, a bi-phasic model based on mixture theory is adopted in simulation. An explicit algorithm is developed and realized by the authors, which conducts the simulation to be a cost-effective tool in MIM technology. In case of the bi-phasic simulation, the viscosity behaviours are necessary to be determined for the flows of each phase while only the viscosity of mixture is measurable by tests. It is a crucial problem for application of the bi-phasic simulation of MIM injection. A reasonable method is hence analysed and proposed to determine the viscosity behaviours of each phase. Even though this method may be furthermore modified in the future, it results in the practical simulation of segregation effects with reasonable parameters. The simulation results are compared with the measurements on injected specimens.展开更多
Water flooding is widely applied for pressure maintenance or increasing the oil recovery of reservoirs.The heterogeneity and wettability of formation rocks strongly affect the oil recovery efficiency in carbonate rese...Water flooding is widely applied for pressure maintenance or increasing the oil recovery of reservoirs.The heterogeneity and wettability of formation rocks strongly affect the oil recovery efficiency in carbonate reservoirs.During seawater injection in carbonate formations,the interactions between potential seawater ions and the carbonate rock at a high temperature can alter the wettability to a more water-wet condition.This paper studies the wettability of one of the Iranian carbonate reservoirs which has been under Persian Gulf seawater injection for more than 10 years.The wettability of the rock is determined by indirect contact angle measurement using Rise in Core technique.Further,the characterization of the rock surface is evaluated by molecular kinetic theory(MKT)modeling.The data obtained from experiments show that rocks are undergoing neutral wetting after the aging process.While the wettability of low permeable samples changes to be slightly water-wet,the wettability of the samples with higher permeability remains unchanged after soaking in seawater.Experimental data and MKT analysis indicate that wettability alteration of these carbonate rocks through prolonged seawater injection might be insignificant.展开更多
The complicated characteristics of the powder were studied by fractal theory. It is illustrated that powder shape, binder structure, feedstock and mold filling flow in powder injection molding process possess obvious ...The complicated characteristics of the powder were studied by fractal theory. It is illustrated that powder shape, binder structure, feedstock and mold filling flow in powder injection molding process possess obvious fractal characteristics. Based on the result of SEM, the fractal dimensions of the projected boundary of carbonylic iron and carbonylic nickel particles were determined to be 1.074±0.006 and 1.230±0.005 respectively by box counting measurement. The results show that the fractal dimension of the projected boundary of carbonylic iron particles is close to smooth curve of one dimension, while the fractal dimension of the projected boundary of carbonylic nickel particle is close to that of trisection Koch curve, indicating that the shape characteristics of carbonylic nickel particles can be described and analyzed by the characteristics of trisection Koch curve. It is also proposed that the fractal theory can be applied in the research of powder injection molding in four aspects.展开更多
目的探讨基于灶点理论的弧刃针疗法治疗顽固性网球肘的临床疗效。方法收集64例顽固性网球肘患者,采用随机数字表法分为对照组和观察组。其中对照组32例,采用局部痛点注射治疗。观察组32例,采用弧刃针疗法治疗,每周治疗1次,均治疗2次,分...目的探讨基于灶点理论的弧刃针疗法治疗顽固性网球肘的临床疗效。方法收集64例顽固性网球肘患者,采用随机数字表法分为对照组和观察组。其中对照组32例,采用局部痛点注射治疗。观察组32例,采用弧刃针疗法治疗,每周治疗1次,均治疗2次,分别记录并比较两组患者治疗前、治疗后1、2、4及24周随访的疼痛数字评分(numberal rating scale,NRS)、肘关节功能评分(Mayo elbow perfor⁃mance score,MEPS)、肩臂手残障(disabilities of the arm,shoulder and hand,DASH)评分以及24周随访时的疾病的疗效评分(Wangxuechang diease efficacy score,WDES)。结果治疗过程中两组患者均未见不良事件发生。两组患者治疗前的NRS、MEPS及DASH差异均无统计学意义(P>0.05);治疗后各时期,两组NRS、MEPS、DASH及24周随访时的WDES较治疗前均改善,治疗1周后,两组NRS差异无统计学意义(P>0.05),治疗2、4及24周随访时的NRS观察组低于对照组;治疗后1、2、4及24周随访时,观察组DASH评分低于对照组,MEPS评分高于对照组,差异有统计学意义(P<0.05),治疗24周后随访时的WDES,观察组优于对照组,差异有统计学意义(P<0.05)。结论局部痛点注射及弧刃针灶点松解治疗顽固性网球肘早期均能缓解疼痛,改善肘关节功能,而局部痛点注射治疗后远期效果欠佳,观察组治疗效果逐渐提升。展开更多
Due to the development of Distributed Generation (DG), which is installed in Medium-Voltage Distribution Networks (MVDNs) such as generators based on renewable energy (e.g., wind energy or solar energy), voltage contr...Due to the development of Distributed Generation (DG), which is installed in Medium-Voltage Distribution Networks (MVDNs) such as generators based on renewable energy (e.g., wind energy or solar energy), voltage control is currently a very important issue. The voltage is now regulated at the MV busbars acting on the On-Load Tap Changer of the HV/MV transformer. This method does not guarantee the correct voltage value in the network nodes when the distributed generators deliver their power. In this paper an approach based on Sensitivity Theory is shown, in order to control the node voltages regulating the reactive power exchanged between the network and the dispersed generators. The automatic distributed voltage regulation is a particular topic of the Smart Grids.展开更多
The statistical properties of a homogeneously broadened ring laser with an injected signal are investigated and the normalized two-mode intensity auto- and cross-correlation functions are calculated by a full saturati...The statistical properties of a homogeneously broadened ring laser with an injected signal are investigated and the normalized two-mode intensity auto- and cross-correlation functions are calculated by a full saturation laser theory with backscattering. The theoretical predictions are in good agreement with the experimental measurements.Further investigation reveals that the backscattering can reduce the fluctuations in the system while the full saturation effect plays a major role when the laser is operated above threshold. It is also quite important to notice that the injected signal can drive the weak mode from incoherent light to coherent light.展开更多
The rheological features of an incompressible axi-symmetric Casson-Maxwell nanofluid flow between two stationary disks are examined.The lower permeable disk is located at z=-a,while the upper disk is placed at z=a.Bot...The rheological features of an incompressible axi-symmetric Casson-Maxwell nanofluid flow between two stationary disks are examined.The lower permeable disk is located at z=-a,while the upper disk is placed at z=a.Both the disks are porous and subjected to uniform injection.The fluid properties such as thermal conductivity vary with temperature.The Cattaneo-Christov thermal expression is implemented along with the Buongiorno nanofluid theory.By operating the similarity functions,the reduced form of the fluid model in terms of ordinary differential equations is obtained and solved by the bvp4 c numerical technique.The physical quantities are demonstrated graphically on the velocity and temperature fields.Three-dimensional flow arrangements and twodimensional contour patterns against several dimensionless variables are also sketched.The numerical values of the local Nusselt and Sherwood numbers for various quantities are presented in tabular set-up.The intensity of the linear relationship between the Nusselt and Sherwood numbers is assessed through Pearson’s product-moment correlation technique.The statistical implication of the linear association between variables is also examined by the t-test statistic approach.展开更多
In basic homological algebra, the flat and injective dimensions of modules play an important and fundamental role. In this paper, the closely related IFP-flat and IFP-injective dimensions are introduced and studied. W...In basic homological algebra, the flat and injective dimensions of modules play an important and fundamental role. In this paper, the closely related IFP-flat and IFP-injective dimensions are introduced and studied. We show that IFP-fd（M） = IFP-id（M＋） and IFP-fd（M＋）=IFP-id（M） for any R-module M over any ring R. Let ：Z-In （resp., ＂Zgv,~） he the class of all left （resp., right） R-modules of IFP-injective （resp., IFP-flat） dimension at most n. We prove that every right R-module has an IFn- preenvelope, （IFn,IF⊥n） is a perfect cotorsion theory over any ring R, and for any ring R with IFP-id（RR） 〈 n, （IIn,II⊥n） is a perfect cotorsion theory. This generalizes and improves the earlier work （J. Algebra 242 （2001）, 447-459）. Finally, some applications are given.展开更多
基于虚拟隐含网络的虚假数据注入攻击(False data injection attack,FDIA)防御控制策略,本文提出了一种基于图论的拓扑优化算法来提高其防御性能.首先,提出了一种图的等效变换方法—权值分配法,实现二分图连接拓扑与二分图拉普拉斯矩阵...基于虚拟隐含网络的虚假数据注入攻击(False data injection attack,FDIA)防御控制策略,本文提出了一种基于图论的拓扑优化算法来提高其防御性能.首先,提出了一种图的等效变换方法—权值分配法,实现二分图连接拓扑与二分图拉普拉斯矩阵的一一对应;进而基于网络拓扑的连通度以及连通图的可去边理论,给出了虚拟隐含网络和二分图连接网络的拓扑选择依据;在考虑拓扑权值的基础上,给出了权值拓扑优化的指标评价函数;通过求解指标评价函数的最小化代价实现拓扑优化选择,从而改善基于虚拟隐含网络的虚假数据注入攻击防御方法的性能.最后,通过在IEEE-14总线电网系统上的仿真验证了所提算法的有效性.展开更多
文摘To predict the segregation effect in metal injection moulding (MIM) injection, a bi-phasic model based on mixture theory is adopted in simulation. An explicit algorithm is developed and realized by the authors, which conducts the simulation to be a cost-effective tool in MIM technology. In case of the bi-phasic simulation, the viscosity behaviours are necessary to be determined for the flows of each phase while only the viscosity of mixture is measurable by tests. It is a crucial problem for application of the bi-phasic simulation of MIM injection. A reasonable method is hence analysed and proposed to determine the viscosity behaviours of each phase. Even though this method may be furthermore modified in the future, it results in the practical simulation of segregation effects with reasonable parameters. The simulation results are compared with the measurements on injected specimens.
基金the financial support of Iranian Offshore Oil Company (IOOC)
文摘Water flooding is widely applied for pressure maintenance or increasing the oil recovery of reservoirs.The heterogeneity and wettability of formation rocks strongly affect the oil recovery efficiency in carbonate reservoirs.During seawater injection in carbonate formations,the interactions between potential seawater ions and the carbonate rock at a high temperature can alter the wettability to a more water-wet condition.This paper studies the wettability of one of the Iranian carbonate reservoirs which has been under Persian Gulf seawater injection for more than 10 years.The wettability of the rock is determined by indirect contact angle measurement using Rise in Core technique.Further,the characterization of the rock surface is evaluated by molecular kinetic theory(MKT)modeling.The data obtained from experiments show that rocks are undergoing neutral wetting after the aging process.While the wettability of low permeable samples changes to be slightly water-wet,the wettability of the samples with higher permeability remains unchanged after soaking in seawater.Experimental data and MKT analysis indicate that wettability alteration of these carbonate rocks through prolonged seawater injection might be insignificant.
文摘The complicated characteristics of the powder were studied by fractal theory. It is illustrated that powder shape, binder structure, feedstock and mold filling flow in powder injection molding process possess obvious fractal characteristics. Based on the result of SEM, the fractal dimensions of the projected boundary of carbonylic iron and carbonylic nickel particles were determined to be 1.074±0.006 and 1.230±0.005 respectively by box counting measurement. The results show that the fractal dimension of the projected boundary of carbonylic iron particles is close to smooth curve of one dimension, while the fractal dimension of the projected boundary of carbonylic nickel particle is close to that of trisection Koch curve, indicating that the shape characteristics of carbonylic nickel particles can be described and analyzed by the characteristics of trisection Koch curve. It is also proposed that the fractal theory can be applied in the research of powder injection molding in four aspects.
文摘目的探讨基于灶点理论的弧刃针疗法治疗顽固性网球肘的临床疗效。方法收集64例顽固性网球肘患者,采用随机数字表法分为对照组和观察组。其中对照组32例,采用局部痛点注射治疗。观察组32例,采用弧刃针疗法治疗,每周治疗1次,均治疗2次,分别记录并比较两组患者治疗前、治疗后1、2、4及24周随访的疼痛数字评分(numberal rating scale,NRS)、肘关节功能评分(Mayo elbow perfor⁃mance score,MEPS)、肩臂手残障(disabilities of the arm,shoulder and hand,DASH)评分以及24周随访时的疾病的疗效评分(Wangxuechang diease efficacy score,WDES)。结果治疗过程中两组患者均未见不良事件发生。两组患者治疗前的NRS、MEPS及DASH差异均无统计学意义(P>0.05);治疗后各时期,两组NRS、MEPS、DASH及24周随访时的WDES较治疗前均改善,治疗1周后,两组NRS差异无统计学意义(P>0.05),治疗2、4及24周随访时的NRS观察组低于对照组;治疗后1、2、4及24周随访时,观察组DASH评分低于对照组,MEPS评分高于对照组,差异有统计学意义(P<0.05),治疗24周后随访时的WDES,观察组优于对照组,差异有统计学意义(P<0.05)。结论局部痛点注射及弧刃针灶点松解治疗顽固性网球肘早期均能缓解疼痛,改善肘关节功能,而局部痛点注射治疗后远期效果欠佳,观察组治疗效果逐渐提升。
文摘Due to the development of Distributed Generation (DG), which is installed in Medium-Voltage Distribution Networks (MVDNs) such as generators based on renewable energy (e.g., wind energy or solar energy), voltage control is currently a very important issue. The voltage is now regulated at the MV busbars acting on the On-Load Tap Changer of the HV/MV transformer. This method does not guarantee the correct voltage value in the network nodes when the distributed generators deliver their power. In this paper an approach based on Sensitivity Theory is shown, in order to control the node voltages regulating the reactive power exchanged between the network and the dispersed generators. The automatic distributed voltage regulation is a particular topic of the Smart Grids.
文摘The statistical properties of a homogeneously broadened ring laser with an injected signal are investigated and the normalized two-mode intensity auto- and cross-correlation functions are calculated by a full saturation laser theory with backscattering. The theoretical predictions are in good agreement with the experimental measurements.Further investigation reveals that the backscattering can reduce the fluctuations in the system while the full saturation effect plays a major role when the laser is operated above threshold. It is also quite important to notice that the injected signal can drive the weak mode from incoherent light to coherent light.
文摘The rheological features of an incompressible axi-symmetric Casson-Maxwell nanofluid flow between two stationary disks are examined.The lower permeable disk is located at z=-a,while the upper disk is placed at z=a.Both the disks are porous and subjected to uniform injection.The fluid properties such as thermal conductivity vary with temperature.The Cattaneo-Christov thermal expression is implemented along with the Buongiorno nanofluid theory.By operating the similarity functions,the reduced form of the fluid model in terms of ordinary differential equations is obtained and solved by the bvp4 c numerical technique.The physical quantities are demonstrated graphically on the velocity and temperature fields.Three-dimensional flow arrangements and twodimensional contour patterns against several dimensionless variables are also sketched.The numerical values of the local Nusselt and Sherwood numbers for various quantities are presented in tabular set-up.The intensity of the linear relationship between the Nusselt and Sherwood numbers is assessed through Pearson’s product-moment correlation technique.The statistical implication of the linear association between variables is also examined by the t-test statistic approach.
基金supported by National Natural Science Foundation of China(10961021,11001222)
文摘In basic homological algebra, the flat and injective dimensions of modules play an important and fundamental role. In this paper, the closely related IFP-flat and IFP-injective dimensions are introduced and studied. We show that IFP-fd（M） = IFP-id（M＋） and IFP-fd（M＋）=IFP-id（M） for any R-module M over any ring R. Let ：Z-In （resp., ＂Zgv,~） he the class of all left （resp., right） R-modules of IFP-injective （resp., IFP-flat） dimension at most n. We prove that every right R-module has an IFn- preenvelope, （IFn,IF⊥n） is a perfect cotorsion theory over any ring R, and for any ring R with IFP-id（RR） 〈 n, （IIn,II⊥n） is a perfect cotorsion theory. This generalizes and improves the earlier work （J. Algebra 242 （2001）, 447-459）. Finally, some applications are given.
文摘基于虚拟隐含网络的虚假数据注入攻击(False data injection attack,FDIA)防御控制策略,本文提出了一种基于图论的拓扑优化算法来提高其防御性能.首先,提出了一种图的等效变换方法—权值分配法,实现二分图连接拓扑与二分图拉普拉斯矩阵的一一对应;进而基于网络拓扑的连通度以及连通图的可去边理论,给出了虚拟隐含网络和二分图连接网络的拓扑选择依据;在考虑拓扑权值的基础上,给出了权值拓扑优化的指标评价函数;通过求解指标评价函数的最小化代价实现拓扑优化选择,从而改善基于虚拟隐含网络的虚假数据注入攻击防御方法的性能.最后,通过在IEEE-14总线电网系统上的仿真验证了所提算法的有效性.
