The greatest service industry and income gainer throughout the world occupies a special role and position in developing geographical areas. This study attempts to use “Reynard” model to investigate the role of touri...The greatest service industry and income gainer throughout the world occupies a special role and position in developing geographical areas. This study attempts to use “Reynard” model to investigate the role of tourism and its effects on the development of rural settlements with emphasis on Pa Ggaleh Village, which is one of the environs in Mamasani, Iran. Due to its historical and religious attractions and natural and cultural landscapes, this village is highly significant and has the potential to become a tourism hub and attract tourists. The methodology applied in this research is cross-sectional. Tourism potentials of Pa Ghaleh village are identified and evaluated in this study. Geological maps, topographies and field data are used to evaluate the district attractions. Their tourism potentials are also evaluated and rated using Reynard model. According to the sub-criteria of rarity and historical geography, the research results indicate that scientific value has the highest rank. In other words, tourism places in Pa Ghaleh village include 72% of scientific value, 0.59% of added value and 0.57% of compound value.展开更多
In this paper the physical influences on the mechanical behavior of a Polyamide 6 (PA 6)/Mont- morillonit (MMT)-nanocomposite are examined by a selected structure modification in a numerical parameter study. Experimen...In this paper the physical influences on the mechanical behavior of a Polyamide 6 (PA 6)/Mont- morillonit (MMT)-nanocomposite are examined by a selected structure modification in a numerical parameter study. Experimental data of tensile tests of three different volume fractions at ambient temperature are used as reference. These were compared to homogenized stress-strain curves calculated with 3D representative volume elements (RVE) under periodic boundary conditions, in which the curve areas are considered until the tensile yield strength is reached. Besides the influence of filler orientation, exfoliation and its volume fraction, both adhesive interface behavior between the filler and matrix, and local partially crystalline interphases around the MMT-plates were also taken into account. A good approximation of the numerical representation of the experimental curves was achieved only after the introduction of the 30 - 40 nm thick partially crystalline interphases with higher stiffness and strength around the MMT-plates. The use of an exclusively isotropic matrix led to an underestimation of the mechanical values. The local modifications of the morphology were assumed to be transversely isotropic both in the elastic and in the plastic region. The transverse plane is defined by the lateral particle surface. Compared with the experimentally determined values of the corresponding Young’s Modulus, an excellent correlation was achieved. The yield strength for the largest volume fraction shows the best agreement with experimental values.展开更多
This paper discusses the utilization of nano-sized fillers in Polyamide 6 to increase the fracture resistance of the composites, which are crucial for various engineering applications. The toughening of the composites...This paper discusses the utilization of nano-sized fillers in Polyamide 6 to increase the fracture resistance of the composites, which are crucial for various engineering applications. The toughening of the composites is achieved by using dispersed nano-scaled rubber particles (Polyether block copolymer) as the inclusion in Polyamide 6 matrix. For a better understanding of the mechanical behavior of the composites, it is indispensable to use analytical and numerical models for evaluating the overall mechanical behavior and damage mechanism of the composite. In this work the toughening mechanism is studied through literature review and by analytical modeling. The mechanical behavior of the composites such as elastic plastic and damage properties are calculated numerically with 3D representative volume element (RVE) models. The numerical results are compared with previously obtained experiments. The influence of volume fraction and aspect ratio of inclusions on the macroscopic stress strain curve as well as the size effect of inclusions and also the failure properties of the composite are studied in detail.展开更多
目的:探讨核磁共振扩散成像技术在大鼠自体血栓栓塞脑缺血和t-PA溶栓治疗模型中的作用。方法:雄性SD大鼠15只,随机分成两组:治疗组10只,假溶栓组5只。大鼠自体血栓大脑中动脉栓塞后行常规MR扫描,磁共振扩散加权成像(DWI)和表观扩散系数(...目的:探讨核磁共振扩散成像技术在大鼠自体血栓栓塞脑缺血和t-PA溶栓治疗模型中的作用。方法:雄性SD大鼠15只,随机分成两组:治疗组10只,假溶栓组5只。大鼠自体血栓大脑中动脉栓塞后行常规MR扫描,磁共振扩散加权成像(DWI)和表观扩散系数(ADC)成像,观察脑缺血范围。缺血2 h进行t-PA溶栓治疗,缺血24 h观察神经功能缺陷评分和脑梗死体积。结果:DWI能显示早期脑梗死。大脑中动脉栓塞后24 h t-PA溶栓组神经功能缺陷得分为1.1分,假溶栓组神经功能得分为3分。栓塞后24 h TTC染色脑梗死面积和体积均显示t-PA溶栓组明显小于假溶栓组。结论:磁共振扩散成像检查保证实验成功率和准确性。自体血栓栓塞和t-PA治疗模型的建立有利于进一步研究该过程中的病理生理改变。展开更多
In this letter, a novel model is proposed for modeling the nonlinearity and memory effects of power amplifiers. The classical Volterra model is modified through a function of the sum of nonlinearity order with sum of ...In this letter, a novel model is proposed for modeling the nonlinearity and memory effects of power amplifiers. The classical Volterra model is modified through a function of the sum of nonlinearity order with sum of memory length. The parameters of this model can be extracted in digital domain since the model is analyzed based on the envelope signals. The model we proposed enables a substantial reduction in the number of coefficients involved, and with excellent accuracy.展开更多
文摘The greatest service industry and income gainer throughout the world occupies a special role and position in developing geographical areas. This study attempts to use “Reynard” model to investigate the role of tourism and its effects on the development of rural settlements with emphasis on Pa Ggaleh Village, which is one of the environs in Mamasani, Iran. Due to its historical and religious attractions and natural and cultural landscapes, this village is highly significant and has the potential to become a tourism hub and attract tourists. The methodology applied in this research is cross-sectional. Tourism potentials of Pa Ghaleh village are identified and evaluated in this study. Geological maps, topographies and field data are used to evaluate the district attractions. Their tourism potentials are also evaluated and rated using Reynard model. According to the sub-criteria of rarity and historical geography, the research results indicate that scientific value has the highest rank. In other words, tourism places in Pa Ghaleh village include 72% of scientific value, 0.59% of added value and 0.57% of compound value.
文摘In this paper the physical influences on the mechanical behavior of a Polyamide 6 (PA 6)/Mont- morillonit (MMT)-nanocomposite are examined by a selected structure modification in a numerical parameter study. Experimental data of tensile tests of three different volume fractions at ambient temperature are used as reference. These were compared to homogenized stress-strain curves calculated with 3D representative volume elements (RVE) under periodic boundary conditions, in which the curve areas are considered until the tensile yield strength is reached. Besides the influence of filler orientation, exfoliation and its volume fraction, both adhesive interface behavior between the filler and matrix, and local partially crystalline interphases around the MMT-plates were also taken into account. A good approximation of the numerical representation of the experimental curves was achieved only after the introduction of the 30 - 40 nm thick partially crystalline interphases with higher stiffness and strength around the MMT-plates. The use of an exclusively isotropic matrix led to an underestimation of the mechanical values. The local modifications of the morphology were assumed to be transversely isotropic both in the elastic and in the plastic region. The transverse plane is defined by the lateral particle surface. Compared with the experimentally determined values of the corresponding Young’s Modulus, an excellent correlation was achieved. The yield strength for the largest volume fraction shows the best agreement with experimental values.
文摘This paper discusses the utilization of nano-sized fillers in Polyamide 6 to increase the fracture resistance of the composites, which are crucial for various engineering applications. The toughening of the composites is achieved by using dispersed nano-scaled rubber particles (Polyether block copolymer) as the inclusion in Polyamide 6 matrix. For a better understanding of the mechanical behavior of the composites, it is indispensable to use analytical and numerical models for evaluating the overall mechanical behavior and damage mechanism of the composite. In this work the toughening mechanism is studied through literature review and by analytical modeling. The mechanical behavior of the composites such as elastic plastic and damage properties are calculated numerically with 3D representative volume element (RVE) models. The numerical results are compared with previously obtained experiments. The influence of volume fraction and aspect ratio of inclusions on the macroscopic stress strain curve as well as the size effect of inclusions and also the failure properties of the composite are studied in detail.
文摘目的:探讨核磁共振扩散成像技术在大鼠自体血栓栓塞脑缺血和t-PA溶栓治疗模型中的作用。方法:雄性SD大鼠15只,随机分成两组:治疗组10只,假溶栓组5只。大鼠自体血栓大脑中动脉栓塞后行常规MR扫描,磁共振扩散加权成像(DWI)和表观扩散系数(ADC)成像,观察脑缺血范围。缺血2 h进行t-PA溶栓治疗,缺血24 h观察神经功能缺陷评分和脑梗死体积。结果:DWI能显示早期脑梗死。大脑中动脉栓塞后24 h t-PA溶栓组神经功能缺陷得分为1.1分,假溶栓组神经功能得分为3分。栓塞后24 h TTC染色脑梗死面积和体积均显示t-PA溶栓组明显小于假溶栓组。结论:磁共振扩散成像检查保证实验成功率和准确性。自体血栓栓塞和t-PA治疗模型的建立有利于进一步研究该过程中的病理生理改变。
文摘In this letter, a novel model is proposed for modeling the nonlinearity and memory effects of power amplifiers. The classical Volterra model is modified through a function of the sum of nonlinearity order with sum of memory length. The parameters of this model can be extracted in digital domain since the model is analyzed based on the envelope signals. The model we proposed enables a substantial reduction in the number of coefficients involved, and with excellent accuracy.
