Spatial modeling of solar photovoltaic power plant in Kabul,Afghanistan

Energy planning and solar plant site selections are vital strategic decisions and one of the most complex executive challenges in the interconnected procedures....     

DEM filtration modelling for granular materials: Comparative analysis of dry and wet approaches

A detailed study comparing two – dry and wet – numerical approaches to model filtration processes at stake in actual granular filters is presented using the discrete element method (DEM). In the first approach, the migration of fines is provided by gravitational forces, while in the second, hydrodynamic forces induce their movement. Numerical filtration tests were performed on granular filters involving materials with different gradings and porosities. The study demonstrated that the wet filtration approach generates higher tortuosity due to the possibility for fines to deviate from direct paths towards more open sideways. It leads to a lower coefficient of retention for the filter than if it were characterised using a dry filtration approach. However, the intensity of this feature greatly depends on the grading and the porosity of the granular filter. Finally, an enhanced dry filtration model designated as the “equivalent cyclic wet filtration model” is presented, which better mimics the results obtained through the preferable wet filtration model compared to the original dry filtration model. This new model constitutes a valuable alternative tool for studies of filtration properties in granular materials.     

新疆南部地区暖冬年与春夏季降水的相关分析

利用春夏季(3~8月)12个站降水资料以及冬季(12~02月)温度资料,通过统计方法选取新疆南部地区温度异常年份与春夏季降水异常年份,并进行相关分析,结果表明:暖冬年份对应的来年春夏季总降水量偏多;反之,冷冬年对应的春夏季降水总量偏少。再利用NCEP/NCAR1960-2000年全球月平均网格点资料分析500 hPa高度场环流特征,结果表明:暖冬年前期环流特征为西低东高型,冷冬年前期环流特征为西高东低型,具有反位相关系。暖冬年后期才为西高东低型,与冷冬年前期相较起点晚,从而影响到来年的环流入夏时间,这可能就是导致暖冬年份来年降水增多的原因之一。     

Identification of chrysotile in local soil at Beypinari village (Sivas-Turkey) regarding mine and health issue

Asbestos is dangerous for health and is forbidden to use in Turkey, but villagers who live in rural eastern part still use it especially for their home for insulation purposes and even as a substitute for baby powder. Therefore, geological and chemical properties of this type of soil, which is near the settlement, should be characterized and identified from the point of view of health. Beypinari asbestos deposits are located at Beypinari village, about 90 km southeast of Sivas, Turkey within Central Anatolian Ophiolites. Therefore, in the present study, the existence of chrysotile in Beypinari asbestos deposit were characterized and identified by mineralogical analysis and by major, trace, REE analysis. The results show that the samples contain different amount of calcite mineral, the main mineral being chrysotile.     

Assessments of Strength Anisotropy and Deformation Behavior of Banded Amphibolite Rocks

Assessment of strength anisotropy in transversely isotropic rocks has been one of the most challenging subjects in rock engineering. However, far too little attention has been paid to banded amphibolite rocks. This study aim to evaluate strength and deformation anisotropy behavior of banded amphibolite rocks. The dynamic mechanical tests including ultrasonic pulse test, uniaxial compressive strength, Brazilian test and deformability test were performed on drilled rock samples as a function of foliation plane angle (β = 0°, 30°, 60° and 90°). The results obtained have shown that the dynamic mechanical properties of amphibolite rocks have different values concerning banding plane. Compression and shear waves taken parallel to the foliation plane show highest values than those obtained in the other directions. Under uniaxial test, the banded amphibolite has a U-shaped anisotropy with maximum strength at β = 90° and minimum strength is obtained when β = 30°. Strength anisotropic index ranges between 0.96 and 1.47. It seems that the high range value of anisotropic index is mainly due to slight undulation of foliation planes, that being not perfectly straight. The results of elastic deformation test show that there is no clear dependence on microstructures characteristics of subtype-amphibolite rocks that controlling modulus “shape-anisotropy”. However, in this study, Young modulus values of amphibolite rocks with β follow both types of shape-anisotropy, “U-shape” and “decreased order-shaped”. Thus, this study recommended that further research be undertaken regarding the role of modulus “shape-anisotropy” within the same lithotype.     

Strong ground motion simulation of the 2003 Bam, Iran, earthquake using the empirical Green’s function method

The 2003 Bam, Iran, earthquake caused catastrophic damage to the city of Bam and neighboring villages. Given its magnitude (M _w ) of 6.5, the damage was remarkably large. Large-amplitude ground motions were recorded at the Bam accelerograph station in the center of Bam city by the Building and Housing Research Center (BHRC) of Iran. We simulated the Bam earthquake acceleration records at three BHRC strong-motion stations—Bam, Abaraq, and Mohammad-Abad—by the empirical Green’s function method. Three aftershocks were used as empirical Green’s functions. The frequency range of the empirical Green’s function simulations was 0.5–10 Hz. The size of the strong motion generation area of the mainshock was estimated to be 11 km in length by 7 km in width. To estimate the parameters of the strong motion generation area, we used 1D and 2D velocity structures across the fault and a combined source model. The empirical Green’s function method using a combination of aftershocks produced a source model that reproduced ground motions with the best fit to the observed waveforms. This may be attributed to the existence of two distinct rupture mechanisms in the strong motion generation area. We found that the rupture starting point for which the simulated waveforms best fit the observed ones was near the center of the strong motion generation area, which reproduced near-source ground motions in a broadband frequency range. The estimated strong motion generation area could explain the observed damaging ground motion at the Bam station. This suggests that estimating the source characteristics of the Bam earthquake is very important in understanding the causes of the earthquake damage.     

Water masses in the Gulf of Aden

Hydrographic data collected from Gulf of Aden since 1920 have been compiled to identify and refine the definitions of water masses in the Gulf of Aden (GA) and to describe their spatio-temporal variability. Four water masses have been identified based on their θ-S characteristics. The Red Sea Water (RSW) that flows from the Red Sea is the most prominent water in the GA; this occupies about 37% of the total volume of Gulf of Aden. The Gulf of Aden Surface Water (∼3%) forms as a mixture of local water and the water from western Arabian Sea during winter and Red Sea surface water during summer. The intermediate water, identified as Gulf of Aden Intermediate Water (GAIW), occupies about 9% of the total volume of GA; a characteristic salinity minimum is associated with it at σ_θ=26.50 kg m⁻³. The northward spread of sub-tropical subsurface water from the south appears to be the major source of GAIW. The bottom water, named Gulf of Aden Bottom Water, showed the least variability. It was formed due to the mixing of Red Sea Water and water of southern origin. Mixing triangles have been used to analyze the composition of water in the GA.     

Arbitrary amplitude ion-acoustic solitary waves in superthermal electron-positron-ion magnetoplasma

Arbitrary amplitude ion-acoustic solitary waves propagating in a magnetized plasma composed of positive ions, superthermal electrons and positrons are investigated. For this purpose, the ions are represented by the hydrodynamical fluid equations while the non-Maxwellian electrons and positrons densities are assumed to follow kappa (κ) distribution. The basic equations are reduced to a pseudoenergy-balance equation. Existence conditions for large amplitude solitary waves are presented. The analytical and numerical analysis of the latter show that the ion-acoustic solitary wave can propagate only in the subsonic region in our plasma system and it is significantly influenced by the plasma parameters. The present analysis could be helpful for understanding the nonlinear ion-acoustic solitary waves propagating in interstellar medium and pulsar wind, which contain an excess of superthermal particles.     

A new heuristic approach to one-dimensional stock-cutting problems with multiple stock lengths in ship production

One-dimensional stock-cutting problem is a commonly encountered problem not only in shipbuilding and construction of coastal structures, but also in other engineering applications related to production and construction. The proposed approach achieves results using cutting patterns directly whereas analytical methods first need to establish a mathematical model. While obtaining ideal solutions of the analytical methods, the new approach limits the wastage to a minimum number of stock materials. In addition, the new approach allows the use of different sized stock materials while it creates various options for the use of single sized stock materials. Use of different sized stock materials broadens the point of view for the solution compared to the use of single sized stock material. Moreover, the new method yields integer results whereas the analytical methods using linear programming usually produce impractical non-integer results. To obtain integer results, the analytical methods need to solve the problem multiple times and screen the alternative solutions.