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DIRECT IMPLEMENTATION OF TIKHONOV REGULARIZATION FOR THE FIRST KIND INTEGRAL EQUATION

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Journal of Computational Mathematics 2022年第3期40卷 335-353页

作者： Meisam Jozi saeed karimi Department of Mathematics Persian Gulf UniversityBushehrIran

A common way to handle the Tikhonov regularization method for the first kind Fredholm integral equations,is first to discretize and then to work with the final linear *** unavoidably inflicts discretization errors which may lead to disastrous results,especially when a quadrature rule is *** propose to regularize directly the integral equation resulting in a continuous Tikhonov *** Tikhonov problem is reduced to a simple least squares problem by applying the Golub-Kahan bidiagonalization(GKB)directly to the integral *** regularization parameter and the iteration index are determined by the discrepancy principle ***,we study the discrete version of the proposed method resulted from numerical evaluating the needed *** on the nodal values of the solution results in a weighted version of GKB-Tikhonov method for linear systems arisen from the Nystr¨om ***,we use numerical experiments on a few test problems to illustrate the performance of our algorithms.

关键词： First kind integral equation Golub-Kahan bidiagonalization Tikhonov regularization Quadrature Discretization

The Influence of Morphology on Photo-catalytic Activity and Optical Properties of Nanocrystalline ZnO Powder

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Nano-Micro Letters 2012年第4期4卷 197-201页

作者： Javad Moghaddam Sara Mollaesmail saeed karimi Materials and Metallurgical Engineering Department Advanced Materials Research Center Sahand University of Technology School of Metallurgy and Materials Engineering University of Tehran

ZnO nano-particles were synthesized via an ammonical ammonium carbonate solution by precipitation method in presence of some additives such as urea, oleic and stearic acid. The morphology and crystallinity of the obtained zinc oxide particles depend critically on the type of additive which was used. Additives also affected the crystal orientation of precipitate nano-particles. SEM, XRD, BET and UV-visible were used to characterize morphology, microstructure, specific surface area and optical properties of the ***-catalysis properties of the as-prepared ZnO powders were evaluated by degradation of methyl red(acid red) in aqueous solution exposed to UV-light. Results suggested a close relationship among the morphology,size and surface area on photo-catalysis and optical properties of the particles. The widest Egvalue(3.56 e V),highest degradation and decolorization efficiency(99%) were obtained from a sample with the smallest grain size(largest surface area) which were used urea as an additive.

关键词： Nano-particles ZnO Precipitation method Optical properties Photocatalytic activity

Shear behavior and dilatancy of an artificial hard-matrix bimrock: An experimental study focusing on the role of blocky structure

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Rock Mechanics Bulletin

Rock Mechanics Bulletin 2024年第4期3卷 83-101页

作者： Amir Yazdani saeed karimi-Nasab Hossein Jalalifar Department of Mining Engineering Isfahan University of TechnologyIsfahanIran Department of Mining Engineering Shahid Bahonar University of KermanKermanIran Department of Petroleum Engineering Shahid Bahonar University of KermanKermanIran

Bimrocks are characterized by their geotechnically significant blocky structure,presenting complex shear *** study investigates the shear behavior and dilatancy of bimrocks featuring a rock-like matrix,such as *** study addresses a gap in current research,which has predominantly examined the shear behavior of soil-matrix bimrocks(bimsoils).Laboratory direct shear tests were performed on idealized models with varying volumetric block proportions(VBPs).The results highlight that blocks exert both positive and negative effects on shear strength,dilation,and block breakage factor(BF),depending on *** indicate 40%and 60%as critical VBPs,revealing distinct shear strength trends within this range,contrary to the dominant downward *** positively impact dilation and BF between 20%and 50%VBP,while negatively affecting them beyond this *** skeleton inherently promotes stable dilatancy under normal stress increments and intensifies stress dependency of shear *** in dilation angle concerning normal stress and VBP suggest the potential for characterizing this factor using equivalent strength and roughness,akin to rockfill *** assessments of equivalent strength revealed positive effects of blocks when VBP was between 30%and 70%.Lastly,the findings indicate that blocks notably impact pre-and post-peak behaviors by reducing shear stiffness and inducing local hardening *** study also discusses the similarities and distinctions in the function of blocks within soil-like and rock-like *** offers new insights into the exact role of blocks in bimrock shear behavior beyond the traditional interpretation through the variation of friction and cohesion.

关键词： Bimrock Rock-like matrix Shear behavior Shear strength Shear dilation Block breakage

A New Iterative Solution Method for Solving Multiple Linear Systems

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Advances in Linear Algebra & Matrix Theory 2012年第3期2卷 25-30页

作者： saeed karimi Department of Mathematics Persian Gulf University Bushehr Iran

In this paper, a new iterative solution method is proposed for solving multiple linear systems A(i)x(i)=b(i), for 1≤ i ≤ s, where the coefficient matrices A(i) and the right-hand sides b(i) are arbitrary in general. The proposed method is based on the global least squares (GL-LSQR) method. A linear operator is defined to connect all the linear systems together. To approximate all numerical solutions of the multiple linear systems simultaneously, the GL-LSQR method is applied for the operator and the approximate solutions are obtained recursively. The presented method is compared with the well-known LSQR method. Finally, numerical experiments on test matrices are presented to show the efficiency of the new method.

关键词： Iterative Method Multiple Linear Systems LSQR Method GL-LSQR Method Projection Method

Safety threshold of intravitreal clonidine in rabbit's eyes

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International Journal of Ophthalmology(English edition) 2018年第1期11卷 25-30页

作者： Homayoun Nikkhah Kiumars Heidari Garfami Mozhgan Rezaei Kanavi Ebrahim Mohammad Nashtaei saeed karimi Masoud Soheilian Ophthalmic Research Center Shahid Beheshti University of Medical Sciences Torfeh Eye Hospital Shahid Beheshti University of Medical Sciences Ocular Tissue Engineering Research Center Shahid Beheshti University of Medical Sciences Labbafinejad Medical Center Shahid Beheshti University of Medical Sciences

AIM： To determine the safe dose of intravitreal clonidine（IVC）, a potential drug for neuroprotection and angiogenesis inhibition in rabbits. METHODS： A total of 28 rabbits were divided into four groups. Three groups received IVC with concentrations of 15（Group A）, 25（Group B）, and 50（Group C） g/0.1 m L and the control group（Group D） received 0.1 m L balanced salt solution（BSS）. To investigate IVC safety, electroretinography（ERG） was performed at baseline, then at 1, 4 and 8 wk after injection. After last ERG, all rabbits were euthanized, their eyes were enucleated and subjected to routine histopathological evaluation, immunohistochemistry for glial fibrillary acidic protein（GFAP） and terminal deoxynucleotidyl transferase d UTP nick end labeling（TUNEL） ***： Based on ERG, histopathology, GFAP and TUNEL assay findings, 15 g IVC was determined as the safe dose in rabbit eyes. While, the results of routine histopathology and TUNEL assay were unremarkable in all groups, toxic effects attributed to 25 and 50 g IVC were demonstrated by ERG and GFAP tests. CONCLUSION： Totally 15 g clonidine is determined as the safe dose for intravitreal injection in rabbits. Contribution of IVC in neuroprotection and inhibition of angiogenesis deserve more studies.

关键词： clonidine intravitreal injection electroretinography glial fibrillary acidic protein TUNEL assay

A New Iterative Scheme for Solving the Semi Sylvester Equation

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Applied Mathematics 2013年第1期4卷 6-10页

作者： saeed karimi Fatemeh Attarzadeh Department of Mathematics Persian Gulf University Bushehr Iran

In this paper, the Galerkin projection method is used for solving the semi Sylvester equation. Firstly the semi Sylvester equation is reduced to the multiple linear systems. To apply the Galerkin projection method, some propositions are presented. The presented scheme is compared with the L-GL-LSQR algorithm in point of view CPU-time and iteration number. Finally, some numerical experiments are presented to show that the efficiency of the new scheme.

关键词： Iterative Method Multiple Linear Systems Galerkin Projection Method L-GL-LSQR Algorithm

Incidence and risk factors of retinopathy of prematurity and utility of the national screening criteria in a tertiary center in Iran

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International Journal of Ophthalmology(English edition) 2019年第8期12卷 1330-1336页

作者： Milad Khorshidifar Homayoun Nikkhah Alireza Ramezani Morteza Entezari NarsisDaftarian Hamid Norouzi Mansoor Shahiari Mitra Radfar Ramin Norinia saeed karimi Clinical Research Development Unit of Torfe Medical Center Shahid Beheshti University of Medical SciencesTehran***Iran Department of Ophthalmology Imam Hossein HospitalShahid Beheshti University of Medical SciencesTehran***Iran Ophthalmic Research Center Shahid Beheshti University ofMedical SciencesTehran16666Iran Ophthalmic Epidemiology Research Center Shahid BeheshtiUniversity of Medical SciencesTehran16666Iran

AIM: To determine the incidence and risk factors of retinopathy of prematurity(ROP) and the sensitivity of current screening criteria in a tertiary eye center in Tehran, Iran. METHODS: In a cross-sectional observational study, neonates weighing ≤2000 grams at birth or born <34 wk gestational age(GA) and all other infants at risk of ROP admitted to the neonatal intensive care unit(NICU) or referred to our ROP clinic were investigated. The incidence of ROP and severe ROP(i.e. patients needing treatment) were determined. The associations between risk factors and the development and severity of ROP were assessed. We also examined the sensitivity of the current national screening guideline in Iran. RESULTS: Among 207 infants, the incidence of ROP and severe ROP was 33.3% and 11.1%, respectively. Mean GA and birth weight(BW) were significantly lower in ROP vs non-ROP infants(29±2 wk vs 33±3 wk, P<0.001;1274±489 g vs 1916±550 g, P<0.001, respectively). Univariate analysis displayed significant association between ROP incidence and GA, BW, NICU admission period, blood transfusion, surfactant usage, sepsis, intraventricular hemorrhage and patent ductus arteriosus(P<0.05 for all). BW [relative risk(RR): 0.857(0.711-0.873), P<0.001], GA [RR: 0.788(0.711-0.873), P<0.001] and blood transfusion [RR: 1.888(0.995-3.583), P=0.052] were independent ROP risk factors. The sensitivity of country-specific screening guidelines was 95.7% and 100% for overall and severe ROP detection, respectively. CONCLUSION: ROP incidence is relatively high in Iran. Identifying ROP risk factors results in more accurate screening and reduces the risk of irreversible vision loss. The ROP screening criteria utilized in Iran are efficient at the present time.

关键词： retinopathy of prematurity incidence risk factors screening Iran

Assessment Capability Forest Regeneration in Different Geographical Aspects Approach Landscape Ecology

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Open Journal of Ecology 2017年第9期7卷 535-553页

作者： Arash Karami saeed karimi Elham Shahi Expert at the Department of Forests Rangeland and Watershed Tehran Iran Faculty of Environment University of Tehran Tehran Iran

In order to determine the relationship between physiographical factors and regeneration changes in forests, and to improve and model natural regeneration status, Gorazbon district in Kheyrod Forest was selected for the study. All available regeneration patches in the area were selected. To achieve spatial structure and quantify metrics related to regeneration patches, the analysis of landscape metrics was used. The results show that 692 regeneration patches were identified at the level of different directions. LAND Metric show the most regeneration percent is related to the western (9%), southern (8.66%), flat areas (8.33%), northern (5.68%) and eastern (4.73%), respectively. In total, the patch coverage level percentage was calculated in the landscape (8.31%). The results related to patch shape metric show that most shapes of patches follow polygon structures and do not have fixed shapes. Results related to the average area of the patch metric show that the average level of patches is between 4 and 5 R. The maximum and minimum distance between patches was observed in the survey between 39 and 520 m respectively. According to the results of the distance average between patch metric, the distribution of patches is random in the southern and western directions, flat areas and pile, but it is uniform in northern directions. It should be noted that the distribution and structure of patches in the northern directions has a better distribution and homogeneity than the other directions. Its canals are used as a natural regeneration model to follow the natural phenomena in forest sustainable management.

关键词： Geographical Directions Natural Distribution Kheyrod Forest Metrics Landscape

玻璃体腔组织纤溶酶原激活剂治疗玻璃体黄斑粘连（英文）

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国际眼科杂志 2018年第2期18卷 219-225页

作者： saeed karimi Masoud Soheilian Homayoun Nikkhah Azadeh Haseli Mofrad Shahid Beheshti医科大学 Torfeh眼科医院眼科研究中心伊朗德黑兰*** Shahid Beheshti医科大学 Labbafinejad眼科医院眼科研究中心伊朗德黑兰*** Shahid Beheshti医科大学 Torfe临床研究发展部伊朗德黑兰***

目的:评估仅玻璃体腔注射组织纤溶酶原激活剂(TPA)对玻璃体黄斑牵引以及玻璃体腔注射TPA和贝伐单抗对视网膜血管疾病的改善作用。方法:前瞻性研究。对24例24眼患者进行干预性系统研究。其中5眼玻璃体黄斑牵引综合征(VMT),19眼视网膜血... 详细信息

目的:评估仅玻璃体腔注射组织纤溶酶原激活剂(TPA)对玻璃体黄斑牵引以及玻璃体腔注射TPA和贝伐单抗对视网膜血管疾病的改善作用。方法:前瞻性研究。对24例24眼患者进行干预性系统研究。其中5眼玻璃体黄斑牵引综合征(VMT),19眼视网膜血管疾病包括:糖尿病黄斑水肿(DME)眼,糖尿病性玻璃体出血(VH)眼,视网膜中央静脉阻塞(CRVO)和新生血管年龄相关性黄斑变性眼(AMD)。在注射前及注射1mo后分别进行视力,B超和OCT检查。3眼VMT接受玻璃体腔单次注射TPA50μg,2眼接受100μg注射。19例视网膜血管疾病患者接受玻璃体腔组织纤溶酶原激活剂(50μg)和贝伐单抗(1.25 mg)联合治疗。结果:纳入病例中男性10眼视网膜血管疾病和VMT患者平均年龄分别为56.8y和60.4y。纳入病例中男性10眼(41.7%),女性14眼(58.3%)。22眼(91.7%)晶状体眼,2眼(8.3%)人工晶状体眼。VMT和视网膜血管疾病的玻璃体后部脱离(PVD)分别为0(0/5)和57.8%(11/19)(P=0.04)。在改善最佳矫正视力(BCVA)和降低黄斑中心凹厚度(CMT)方面,与无PVD眼相比,有PVD眼改善更多。结论:在VMT患者中,单独玻璃体腔内注射TPA不能成功诱导玻璃体后部完全脱离。玻璃体腔联合注射TPA和贝伐单抗可引起视网膜血管疾病患者玻璃体后部脱离,提高最佳矫正视力以及降低黄斑中心凹厚度。

关键词：贝伐单抗玻璃体后部脱离组织纤维蛋白溶酶原激活剂