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Nonlocal integral elasticity analysis of beam bending by using finite element method
Taghizadeh, M.,Ovesy, H.R.,Ghannadpour, S.A.M. Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.4
In this study, a 2-D finite element formulation in the frame of nonlocal integral elasticity is presented. Subsequently, the bending problem of a nanobeam under different types of loadings and boundary conditions is solved based on classical beam theory and also 3-D elasticity theory using nonlocal finite elements (NL-FEM). The obtained results are compared with the analytical and numerical results of nonlocal differential elasticity. It is concluded that the classical beam theory and the nonlocal differential elasticity can separately lead to significant errors for the problem under consideration as distinct from 3-D elasticity and nonlocal integral elasticity respectively.
Geomechanical and thermal reservoir simulation during steam flooding
Taghizadeh, Roohollah,Goshtasbi, Kamran,Manshad, Abbas Khaksar,Ahangari, Kaveh Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.4
Steam flooding is widely used in heavy oil reservoir with coupling effects among the formation temperature change, fluid flow and solid deformation. The effective stress, porosity and permeability in this process can be affected by the multi-physical coupling of thermal, hydraulic and mechanical processes (THM), resulting in a complex interaction of geomechanical effects and multiphase flow in the porous media. Quantification of the state of deformation and stress in the reservoir is therefore essential for the correct prediction of reservoir efficiency and productivity. This paper presents a coupled fluid flow, thermal and geomechanical model employing a program (MATLAB interface code), which was developed to couple conventional reservoir (ECLIPSE) and geomechanical (ABAQUS) simulators for coupled THM processes in multiphase reservoir modeling. In each simulation cycle, time dependent reservoir pressure and temperature fields obtained from three dimensional compositional reservoir models were transferred into finite element reservoir geomechanical models in ABAQUS as multi-phase flow in deforming reservoirs cannot be performed within ABAQUS and new porosity and permeability are obtained using volumetric strains for the next analysis step. Finally, the proposed approach is illustrated on a complex coupled problem related to steam flooding in an oil reservoir. The reservoir coupled study showed that permeability and porosity increase during the injection scenario and increasing rate around injection wells exceed those of other similar comparable cases. Also, during injection, the uplift occurred very fast just above the injection wells resulting in plastic deformation.
Taghizadeh, Roohollah,Goshtasbi, Kamran,Manshad, Abbas Khaksar,Ahangari, Kaveh Techno-Press 2019 Advances in energy research Vol.6 No.1
Anthropogenic greenhouse gas emissions are rising rapidly despite efforts to curb release of such gases. One long term potential solution to offset these destructive emissions is the capture and storage of carbon dioxide. Partially depleted hydrocarbon reservoirs are attractive targets for permanent carbon dioxide disposal due to proven storage capacity and seal integrity, existing infrastructure. Optimum well completion design in depleted reservoirs requires understanding of prominent geomechanics issues with regard to rock-fluid interaction effects. Geomechanics plays a crucial role in the selection, design and operation of a storage facility and can improve the engineering performance, maintain safety and minimize environmental impact. In this paper, an integrated geomechanics workflow to evaluate reservoir caprock integrity is presented. This method integrates a reservoir simulation that typically computes variation in the reservoir pressure and temperature with geomechanical simulation which calculates variation in stresses. Coupling between these simulation modules is performed iteratively which in each simulation cycle, time dependent reservoir pressure and temperature obtained from three dimensional compositional reservoir models in ECLIPSE were transferred into finite element reservoir geomechanical models in ABAQUS and new porosity and permeability are obtained using volumetric strains for the next analysis step. Finally, efficiency of this approach is demonstrated through a case study of oil production and subsequent carbon storage in an oil reservoir. The methodology and overall workflow presented in this paper are expected to assist engineers with geomechanical assessments for reservoir optimum production and gas injection design for both natural gas and carbon dioxide storage in depleted reservoirs.
Taghizadeh, Shirin,Sankian, Mojtaba,Ajami, Abolghasem,Tehrani, Mohsen,Hafezi, Nasim,Mohammadian, Rajeeh,Farazmandfar, Touraj,Hosseini, Vahid,Abbasi, Ali,Ajami, Maryam The Korean Gastric Cancer Association 2014 Journal of gastric cancer Vol.14 No.3
Purpose: Vascular endothelial growth factor (VEGF) is one of the most important growth factors for metastatic tumors. To clarify the role of VEGF-A and C in patients with peptic ulcer disease (PUD) or gastric cancer (GC), we evaluated the expression levels of these two molecules. We also analyzed the effect of Helicobacter pylori infection on VEGF-A and C expression levels. Materials and Methods: Patients with dyspepsia who needed diagnostic endoscopy were selected and divided into three groups: nonulcer dyspepsia (NUD), PUD, and GC, according to their endoscopic and histopathological results. Fifty-two patients with NUD, 50 with PUD, and 38 with GC were enrolled in this study. H. pylori infection was diagnosed by the rapid urease test. After RNA extraction and synthesis of cDNA, the expression levels of VEGF-A and C were determined by quantitative reverse transcriptase polymerase chain reaction. Results: The VEGF-C expression level in the PUD and GC groups was significantly higher than that in the NUD group. Moreover, the VEGF-A expression level in the PUD and GC groups was higher than in the NUD group, although the differences were not statistically significant. Significant positive correlations were also observed between the expression levels of these two molecules in the PUD and GC groups. In addition, the expression levels of these two molecules were higher in H. pylori positive patients with PUD or GC than in H. pylori negative patients of the same groups; however, these differences did not reach statistical significance. Conclusions: Up-regulation of VEGF-C expression during gastric mucosal inflammation may play a role in the development of peptic ulcers or GC.
TAGHIZADEH, N. The Honam Mathematical Society 2005 호남수학학술지 Vol.27 No.2
In this paper we discuss on the uniquenss of the solution of partial differential equations: (1) $${\frac{{\partial}w}{{\partial}{\bar{z}}}}=F(z,\;w,\;{\frac{{\partial}w}{{\partial}z}}}+G(z,\;w.{\bar{w})$$ in the sobolev space $W_{1,p}(D)$.
THE EXACT SOLUTION OF KLEIN-GORDON'S EQUATION BY FORMAL LINEARIZATION METHOD
Taghizadeh, N.,Mirzazadeh, M. The Honam Mathematical Society 2008 호남수학학술지 Vol.30 No.4
In this paper we discuss on the formal linearization and exact solution of Klein-Gordon's equation (1) $u_{tt}-au_{xx}+bu-cu^3=0 a,b,c{\in}R^+$ So that we know an efficient method for constructing of particular solutions of some nonlinear partial differential equations is introduced.
Roya Taghizadeh,,Yaghoub Fathipour,Karim Kamali 한국응용곤충학회 2008 Journal of Asia-Pacific Entomology Vol.11 No.3
Development of Stethorus gilvifrons (Mulsant), a predator of two spotted spider mite (Tetranychus urticae Koch), was studied under laboratory conditions at constant temperatures of 15, 20, 25, 28, 30, 35 and 40°C. No development occurred at 40°C. The total development time at temperatures tested was 56.47, 31.19, 18.53, 17.54, 12.49, and 9.27days, respectively, which indicated a significant decrease of development time with increasing temperature. Using the linear model, the estimated low temperature threshold for egg, larva, prepupa, pupa, and total immature stage of S. gilvifrons was 14.11, 10.86, 11.33, 17.04, and 12.47°C, respectively while the thermal constant for these stages was 36.36, 153.14, 11.63, 25.25, and 222.72 degree-days, respectively. Development of Stethorus gilvifrons (Mulsant), a predator of two spotted spider mite (Tetranychus urticae Koch), was studied under laboratory conditions at constant temperatures of 15, 20, 25, 28, 30, 35 and 40°C. No development occurred at 40°C. The total development time at temperatures tested was 56.47, 31.19, 18.53, 17.54, 12.49, and 9.27days, respectively, which indicated a significant decrease of development time with increasing temperature. Using the linear model, the estimated low temperature threshold for egg, larva, prepupa, pupa, and total immature stage of S. gilvifrons was 14.11, 10.86, 11.33, 17.04, and 12.47°C, respectively while the thermal constant for these stages was 36.36, 153.14, 11.63, 25.25, and 222.72 degree-days, respectively.