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Above- and below-ground biomass and carbon stocks of different tree plantations in central Iran

Journal of Arid Land 2016年第1期8卷 138-145页

作者： Hormoz SOHRABI siavash BAKHTIARV-BAKHTIARI Kourosh AHMADI Faculty of Natural Resources and Marine Science Tarbiat Modares University Faculty of Natural Resources and Earth Science University of Shahrekord

In arid and semi-arid lands using industrial wastewater for irrigating tree plantations offers a great opportunity to fulfill the purpose of Clean Development Mechanism by sequestering carbon in living tissues as well as in soil. Selection of tree for plantation has a great effect on the goal achievements, especially when the managers deal with afforestation projects rather than reforestation projects. The objective of this study was to quantify the above- and below-ground biomass accumulation and carbon storages of the 17-year-old monoculture plantations of mulberry (Morus alba L.), black locust (Robinia pseudoacacia L.), Eldar pine (Pinus eldarica Medw.) and Arizona cypress (Cupressus arizonica Greene) planted in central Iran. To assess the potential carbon storage, we destructively measured individual above- and below-ground tree biomass and developed and scaled models at stand level. Furthermore, carbon content at three soil depths (0–15, 15–30, 30–45 cm), the litter and the understory were assessed in sample plots. The results showed that the total amount of carbon stored by Eldar pine (36.8 Mg/hm2) was higher than those stored by the trees in the other three plantations, which were 23.7, 10.0, and 9.6 Mg/hm2 for Arizona cypress, mulberry and black locust plantations, respectively. For all the species, the above-ground biomass accumulations were higher than those of the below-ground. The root mass fractions of the deciduous were larger than those of the coniferous. Accordingly, the results indicate that the potential carbon storages of the coniferous were higher than those of the deciduous in arid regions.

关键词： carbon storage biomass coniferous deciduous central Iran

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Histopathologic findings of keratoconus corneas underwent penetrating keratoplasty according to topographic measurements and keratoconus severity

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International Journal of Ophthalmology(English edition) 2017年第11期10卷 1640-1646页

作者： Mohammad Naderan Ali Jahanrad siavash Balali School of Medicine Tehran University of Medical SciencesTehran ***Iran School of Medicine AJA University of Medical SciencesTehran ***Iran

AIM： To investigate the histopathologic and morphological changes of the corneas with keratoconus（KC） undergoing penetrating keratoplasty（PKP） according to topographic findings and severity of ***： The corneal tissue of 35 samples with KC was retrospectively evaluated with conventional light microscopy. Topographic and pachymetric parameters of keratoconus corneas by means of Pentacam such as mean keratometry（K） and central corneal thickness（CCT） were recorded. Severity of KC was graded according to Amsler-Krumeich classification. RESULTS： Epithelial thinning and breaks in Bowman＇s layer are the most common findings in keratoconus corneas（94.3% and 82.9% corneas, respectively）. The results revealed statistically significant higher mean K value and lower CCT in the keratoconus corneas that were affected by epithelial thinning, breaks in the Bowman＇s layer, folds in the Descemet＇s membrane, epithelial scars, breaks in Descemet＇s membrane, and stromal scars than those corneas without these findings（P〈0.05）. Moreover, those corneas with epithelial thinning, breaks in the Bowman＇s layer, folds in Descemet＇s membrane, epithelial scars, and stromal scars had significantly more severe disease than those corneas without these findings（P〈0.05）. The presence of the stromal and epithelial scars were associated with the higher KC severity, in which, respectively, 87.5% and 80.0% of the corneas with stromal and epithelial scars had stage 4 of the KC severity. CONCLUSION： It seems that there are some specific patterns in histologic changes of the keratoconus corneas. The presence of pathologic findings was correlatedwith thinner and steeper corneas. Epithelial or stromal scars were associated with the highest disease severity. The description of histopathologic findings of KC may help in elucidating the pathogenesis of the disease and help pathologist in differentiating KC from other corneal diseases.

关键词： cornea ectasia keratoconus morphology pathology topography severity

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CFD modeling of catalyst pellet for oxidative coupling of methane:Heat transfer and reaction

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Particuology 2013年第5期11卷 506-513页

作者： Ramin Maghrebi Nakisa Yaghobi siavash Seyednejadian Mitra H.Tabatabaei Department of Chemical Engineering South-Tehran Branch.Islamic Azad UniversityP.O.Box 11365/4435.TehranIran Iran Polymer and Petrochemical Institute P.O.Box 14965/115Tehran.Iran

This study deals with the phenomena occuring at single-pellet catalyst scale for the oxidative coupling of methane where heat transfer plays an important role. Computational fluid dynamics （CFD） is used for obtaining detailed rate and temperature profiles through the porous catalytic pellet where reaction and diffusion compete, lntra-particle temperature and concentration gradients were taken into account by solving heat transfer coupled with continuity equations in the catalyst pellet. In heat transfer, the energy term due to highly exothermic reaction was considered. Two external programs were successfully implemented into the CFD-code as kinetic and heat of reaction terms. Simulation results showed that reaction was favored at the beginning for the pellet, followed by diffusion predomination. The results of CFD simulation indicate that temperature variation within the catalyst pellet is 〈2 K due to exothermic oxidation. The results showed further that exothermic oxidation reactions occurred prior to endothermic coupling reaction in the pellet.

关键词： Catalyst pelletOxidative coupling of methaneModelingCFDKinetics

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Natural coupled orbit-attitude periodic motions in the perturbed-CRTBP including radiated primary and oblate secondary

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Astrodynamics 2023年第2期7卷 229-249页

作者： Majid Bakhtiari Ehsan Abbasali siavash Sabzy Amirreza Kosari School of Advanced Technologies Iran University of Science and TechnologyNarmakTehran 16844Iran Aerospace Group Faculty of New Sciences and TechnologiesUniversity of TehranNorth Kargar StreetTehranIran

This study investigated periodic coupled orbit-attitude motions within the perturbed circular restricted three-body problem(P-CRTBP)concerning the perturbations of a radiated massive primary and an oblate *** radiated massive primary was the Sun,and each planet in the solar system could be considered an oblate *** the problem has no closed-form solution,numerical methods were ***,the general response of the problem could be non-periodic or periodic,which is significantly depended on the initial conditions of the orbit-attitude ***,the simultaneous orbit and attitude initial states correction(SOAISC)algorithm was introduced to achieve precise initial *** the other side,the conventional initial guess vector was essential as the input of the correction algorithm and increased the probability of reaching more precise initial ***,a new practical approach was developed in the form of an orbital correction algorithm to obtain the initial conditions for the periodic orbit of the *** new proposed algorithm may be distinguished from previously presented orbital correction algorithms by its ability to propagate the P-CRTBP family orbits around the Lagrangian points using only one of the periodic orbits of the unperturbed CRTBP(U-CRTBP).In addition,the Poincarémap and Floquet theory search methods were used to recognize the various initial guesses for attitude *** of these search methods was able to identify different initial guesses for attitude ***,as a new innovation,these search methods were applied as a powerful tool to select the appropriate inertia ratio for a satellite to deliver periodic responses from the coupled *** the mentioned perturbations to the U-CRTBP could lead to the more accurate modeling of the examination environment and a better understanding of a spacecraft's natural motion.A comparison between the orbit-attitude natural motions in the

关键词： oblate and radiated primary perturbed periodic orbit-attitudebehavior periodic orbit three-body problem Lagrangian points

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Experimental Investigation of the Effects of Various Plasma Actuator Configurations on Lift and Drag Coefficients of a Circular Cylinder Including the Effects of Electrodes

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Chinese Journal of Aeronautics 2012年第3期25卷 311-324页

作者： siavash TABATABAEIAN Masoud MIRZAEI Asghar SADIGHZADEH Vahid DAMIDEH Abdollah SHADARAM School of Aerospace Engineering K. N. Toosi University of Technology Atomic Energy Organization of Iran (AEOI) School of physics Shahid Beheshti University School of Mechanical Engineering K. N. Toosi University of Technology

In this paper, the effects of the existence of plasma actuator electrodes and also various configurations of the actuator for controlling the flow field around a circular cylinder are experimentally investigated. The cylinder is made of PVC （Polyvinyl Chloride） and considered as a dielectric barrier. Two electrodes are fiush-mounted on the surface of the cylinder and are connected to a DC high voltage power supply lbr generation of electrical discharge. Pressure distribution results show that the existence of the electrodes and also the plasma are able to change the pressure distribution around the cylinder and consequently the lili and drag coefficients. It is found that the effect of the existence of the electrodes is comparable with the effect of plasma actuator in con- trolling the flow field around the cylinder and this effect is not reported by other researchers. Eventually it is concluded that the existence of the electrodes or any extra obiects on the cylinder and also the existence of the plasma are capable of changing the flow field structure around the cylinder so that the behavior of the lift and drag coefficients of the cylinder will be changed significantly.

关键词： plasma actuator DC high voltage power supply generalized glow regime flow control wind tunnel

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Modeling the hydration,viscosity and ultrasonic property evolution of class G cement up to 90℃ and 200 MPa by a scale factor method

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Petroleum Science 2023年第4期20卷 2372-2385页

作者： Li-Jun Sun Xue-Yu Pang siavash Ghabezloo Hai-Bing Yan School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongPR China Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)) Ministry of EducationQingdao266580ShandongPR China Navier Ecole des PontsUniv Gustave EiffelCNRSMarne-la-ValleeFrance CNPC Chuanqing Drilling Engineering Co.Ltd.(CCDC) Chengdu610051SichuanPR China

A comprehensive experimental program has been performed to characterize the hydration and engineering property evolution of a class G oil well cement under various curing temperatures from 30 to 90℃.The progress of hydration was monitored by isothermal calorimetry(atmospheric pressure);the viscosity evolution was measured using a high temperature and high pressure consistometer(up to 200 MPa);the ultrasonic property development was evaluated by an ultrasonic cement analyzer(up to 100 MPa).Test results indicate that the influences of curing temperature and pressure on the hydration,viscosity and ultrasonic property development can be modeled by a scale factor method that is similar to the maturity method used in the concrete ***,the key parameters of the scale factor model,namely the apparent activation energy and the apparent activation volume of cement showed obvious variations with test method and curing *** test results indicate that the curing temperature has a stronger effect on cement hydration rate than viscosity and ultrasonic property development rate,while the curing pressure has a much stronger influence on cement slurry properties before setting(viscosity)than after setting(ultrasonic property).

关键词： Activation energy Activation volume Isothermal calorimetry Consistency Ultrasonic property

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Estimation of aboveground tree carbon stock using SPOT-HRG data (a case study: Darabkola forests)

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Journal of Forestry Research 2017年第6期28卷 1172-1179页

作者： Masoumeh Fatholahi Asghar Fallah Seyed Mohammad Hojjati siavash Kalbi Department of Natural Resource Sari University of Agricultural Sciences and Natural Resources SariMazandaran 48151 Iran

Forests are among the most important carbon sinks on earth. However, their complex structure and vast areas preclude accurate estimation of forest carbon *** sets from forest monitoring using advanced satellite imagery are now used in international policy *** sets enable tracking of emissions of COinto the atmosphere caused by deforestation and other types of land-use changes. The aim of this study is to determine the capability of SPOT-HRG Satellite data to estimate aboveground carbon stock in a district of Darabkola research and training forest, Iran. Preprocessing to eliminate or reduce geometric error and atmospheric error were performed on the images. Using cluster sampling, 165 sample plots were taken. Of 165 plots, 81 were in natural habitats, and 84 were in forest plantations. Following the collection of ground data, biomass and carbon stocks were quantified for the sample plots on a per hectare basis. Nonparametric regression models such as support vector regression were used for modeling purposes with different kernels including linear, sigmoid, polynomial, and radial basis *** results showed that a third-degree polynomial was the best model for the entire studied areas having an root mean square error, bias and accuracy, respectively, of 38.41,5.31, and 62.2; 42.77, 16.58, and 57.3% for the best polynomial for natural forest; and 44.71, 2.31, and 64.3%for afforestation. Overall, these results indicate that SPOTHRG satellite data and support vector machines are useful for estimating aboveground carbon stock.

关键词： Aboveground carbon stock Support vector machine SPOT-HRG Darabkola

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Lattice-based Cryptosystems Security and Functionality Enhancement

Lattice-based Cryptosystems Security and Functionality Enhan...

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作者： siavash Mirzaee 上海交通大学

学位级别：硕士

密码系统可应用于我们数字世界中所需的许多应用。这包括执行安全加密和解密;消息签名的发布和认证。散列函数、对称密钥或私有密钥,如流密码和分组密码仍然被广泛用于快速消息加密。除此以外,一些更现代化的不对称密码技术,如RSA,DLP和... 详细信息

密码系统可应用于我们数字世界中所需的许多应用。这包括执行安全加密和解密;消息签名的发布和认证。散列函数、对称密钥或私有密钥,如流密码和分组密码仍然被广泛用于快速消息加密。除此以外,一些更现代化的不对称密码技术,如RSA,DLP和ECC,对于其自身权限的使用至关重要。近年来,一些其他术语,如用于密码货币的块链,MPC(多方计算)等被不断创新以满足我们社会未来的需求。由于在量子计算机出现之前提出的量子算法在未来几年将不断被实例化,因此上述经典的对称和非对称密码系统对于强大的量子计算来讲不再具有相应的安全性。研究人员提出的基于代码和基于格的密码系统的新结构将在后量子计算时代提供系统安全保障。本文首先分析了第一代和第二代基于格的密码技术。传统采用的经典采样方法将遭受主动攻击的威胁。综合分析表明,第一代系统缺乏足够的安全措施,使得它们在LLL降维攻击下处于危险之中。另外,第一代系统对新的主动攻击呈现出较弱的防御能力。另一方面,虽然第二代结构提供了更好的效率和安全性来抵御主动攻击,但它们仍然缺乏由于无效和简单的采样方法导致的相当大的安全限制。接着,本文提出了两种新的采样算法,分别称为概率分布函数选择算法(APDF)和概率分布函数组合算法(CPDF)。与以前的方法相比,新的采样方法可以显著改善第二代系统的安全性能。APDF算法的核心思想是借助真随机数生成器(TRNG)和伪随机数生成器(PRNG)从任意资源中提取样本。CPDF算法提出了一种新颖的方法,即结合前面的APDF算法中采用的大量PDF来增加对敌手的混淆,从而使系统更加安全。然后本文对提出的方法进行了仿真和数学分析。结果表明APDF算法和CPDF算法可以分别提高系统的效率和安全性。最后本文证明了APDF算法和CPDF算法可以很容易地应用于第二代基于格的密码系统结构。

关键词：基于格的密码学量子计算后量子密码 LLL规约

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Global stability analysis of computer networks with arbitrary topology and time-varying delays

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第3期11卷 214-226页

作者： Behrooz REZAIE Mohammad-Reza JAHED MOTLAGH siavash KHORSANDI Morteza ANALOUI Deparment of Electrical Engineering Iran University of Science and Technology Department of Computer Engineering and Information Technology Amirkabir University of Technology Deparment of Computer Engineering Iran University of Science and Technology

In this paper,we determine the delay-dependent conditions of global asymptotic stability for a class of multi-dimensional nonlinear time-delay systems with application to computer communication networks. A nonlinear delayed model is considered for a rate-based congestion control system of a heterogeneous network with arbitrary topology and time-varying delays. We propose a Lyapunov-based method to obtain a sufficient condition under which global asymptotic stability of the equilibrium is guaranteed. The main contribution of the paper lies in considering time variations of delays in a heterogeneous network which may be applicable in actual networks. Moreover,we obtain conditions for Internet-style networks with multi-source multi-link topology. We first prove the stability for a class of nonlinear time-delay systems. Then,we apply the results to a Kelly's rate-based ap-proximation of the congestion control system.

关键词： Intemet congestion control Global stability Nonlinear time-delay system Time-varying delay

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Mixed-effects modeling for tree height prediction models of Oriental beech in the Hyrcanian forests

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Journal of Forestry Research 2018年第5期29卷 1195-1204页

作者： siavash Kalbi Asghar Fallah Pete Bettinger Shaban Shataee Rassoul Yousefpour Sari Agriculture and Natural Resource University SariMazandaran Iran Warnell School of Forestry and Natural Resources University of Georgia Athens GA USA Gorgan Agriculture and Natural Resource University Gorgan Golestan Iran Faculty of Environment and Natural Resources University of Freiburg Freiburg Germany

Height–diameter relationships are essential elements of forest assessment and modeling *** this work,two linear and eighteen nonlinear height–diameter equations were evaluated to find a local model for Oriental beech（Fagus orientalis Lipsky） in the Hyrcanian Forest in *** predictive performance of these models was first assessed by different evaluation criteria： adjusted R^2（R^2_（adj））,root mean square error（RMSE）,relative RMSE（%RMSE）,bias,and relative bias（%bias） *** best model was selected for use as the base mixed-effects *** parameters for test plots were estimated with different tree selection *** show that the Chapman–Richards model had better predictive ability in terms of adj R^2（0.81）,RMSE（3.7 m）,%RMSE（12.9）,bias（0.8）,%Bias（2.79） than the other ***,the calibration response,based on a selection of four trees from the sample plots,resulted in a reduction percentage for bias and RMSE of about 1.6–2.7%.Our results indicate that the calibrated model produced the most accurate results.

关键词： Random effects Tree height Calibration Sangdeh forest Chapman–Richards model Oriental beech

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