A stochastic computational method based on goal-oriented error estimation for heterogeneous geological materials

Ghorashi, S.Sh.,Lahmer, T.,Bagherzadeh, A.S.,Zi, G.,Rabczuk, T. Elsevier 2017 Engineering geology Vol.225 No.-

<P><B>Abstract</B></P> <P>Computational modeling of geological materials is challenging. Firstly, they are heterogeneous with numerous uncertainties in the input parameters and secondly, the computational cost of modeling geological structures is time consuming due to the large and different length scales involved. In this article, we propose an efficient computational method for heterogeneous geological materials based on goal oriented error estimation and adaptive mesh refinement. Instead of estimating the error in a specific norm, the proposed novel error estimation approach which is called dual-weighted residual error estimation, approximates the error with respect to the quantity of interest. The dual-weighted residual error estimation is a dual-based scheme which requires an adjoint problem. The adjoint or dual problem is described by defining the quantity of interest in a functional form. Then by solving the primal and dual problems, errors in terms of the specified quantities are calculated. In many applications in engineering geology, the material is heterogeneous. In such cases, the material properties can be regarded as random fields. This variety of material properties leads to non-uniform distributions of the solution gradients, e.g. stresses. Therefore, it is vital to apply a reliable error estimation approach to be able to do efficiently the mesh-adaptivity procedure with regard to varying material parameters with pre-defined correlation lengths. Hence, the proposed error estimator is extended by accounting for a random field model to describe the material properties. Local estimated errors are exploited in order to accomplish the mesh adaptivity procedure. The goal-oriented mesh adaptivity controls the local errors in terms of the prescribed quantities. Both refinement and coarsening processes are applied to raise the efficiency. The performance of the proposed computational approach is demonstrated for several examples.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel adaptive methods for geological materials </LI> <LI> The method accounts for random fields and heterogeneities. </LI> <LI> It is shown the method is computationally faster than other adaptive methods. </LI> </UL> </P>

Polymorphism of Bovine Lymphocyte Antigen DRB3.2 Alleles in Iranian Native Sarabi Cows

Pashmi, M.,Ghorashi, S.A.,Salehi, A.R.,Moini, M.,Javanmard, A.,Qanbari, S.,Yadranji-Aghdam, S. Asian Australasian Association of Animal Productio 2006 Animal Bioscience Vol.19 No.6

Sarabi cows (n = 136) from the Sarabi Breeding Station were genotyped at bovine lymphocyte antigen (BoLA)-DRB3.2 locus by a genotyping system that used the polymerase chain reaction and restriction fragment length polymorphism. Genomic DNA was extracted from whole blood samples. A two-step polymerase chain reaction was carried out in order to amplify a 284 base-pair fragment of target gene. Nested-PCR products were digested with three restriction endonuclease enzymes RsaI, BstYI and HaeIII. Digested fragments were analyzed by polyacrylamide gel electrophoresis. Twenty-six BoLA-DRB3.2 alleles were identified with frequencies ranging from 0.4 to 15.1%. Six new allele types observed in this study have not been reported previously. Identified alleles include: BoLA-DRB3.$2^*1$, $^*2$, $^*4$, $^*6$, $^*8$, $^*12$, $^*13$, $^*14$, $^*15$, $^*16$, $^*17$, $^*23$, $^*24$, $^*25$, $^*28$, $^*32$, $^*34$, $^*35$, $^*36$, $^*37$, $^*42$, $^*46$, $^*51$, $^*kba$, $^*laa$ and $^*vaa$. Their frequencies were found to be 0.4, 0.4, 0.7, 11.4, 1.1, 1.8, 2.9, 2.2, 4.4, 9.6, 1.1, 13.6, 0.4, 0.4, 1.1, 0.7, 0.4, 6.2, 2.2, 3.7, 1.1, 7.7, 1.5, 15.1, 2.6 and 7.3% respectively. The six most frequent alleles (DRB3.2 $^*6$, $^*16$, $^*23$, $^*46$, $^*kba$ and $^*vaa$) accounted for 64.7% of the alleles in the population of this herd. Numerous studies on this locus, covering different breeds, has revealed the existence of various alleles in this locus, and new investigations have introduced novel alleles. With respect to the high number of the observed alleles in this survey and the novelty of some alleles with no previous record of reporting, it is plausible to conclude that the BoLA-DRB3.2 locus is highly polymorphic in Iranian native Sarabi cows.

A Novel WBAN MAC protocol with Improved Energy Consumption and Data Rate

( Sanaz Rezvani ),( S. Ali Ghorashi ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.9

Wireless Body Area Networks (WBANs) are introduced as an enabling technology in tele-health for patient monitoring. Designing an efficient Medium Access Control (MAC) protocol is the main challenge in WBANs because of their various applications and strict requirements such as low level of energy consumption, low transmission delay, the wide range of data rates and prioritizing emergency data. In this paper, we propose a new MAC protocol to provide different requirements of WBANs targeted for medical applications. The proposed MAC provides an efficient emergency response mechanism by considering the correlation between medical signals. It also reduces the power consumption of nodes by minimizing contention access, reducing the probability of the collision and using an efficient synchronization algorithm. In addition, the proposed MAC protocol increases the data rate of the nodes by allocating the resources according to the condition of the network. Analytical and simulation results show that the proposed MAC protocol outperforms IEEE 802.15.4 MAC protocol in terms of power consumption level as well as the average response delay. Also, the comparison results of the proposed MAC with IEEE 802.15.6 MAC protocol show a tradeoff between average response delay and medical data rate.

A Fair Radio Resource Allocation Algorithm for Uplink of FBMC Based CR Systems

( Hosseinali Jamal ),( Seyed Ali Ghorashi ),( Seyed Mohammad-sajad Sadough ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.6

Spectrum scarcity seems to be the most challenging issue to be solved in new wireless telecommunication services. It is shown that spectrum unavailability is mainly due to spectrum inefficient utilization and inappropriate physical layer execution rather than spectrum shortage. Daily increasing demand for new wireless services with higher data rate and QoS level makes the upgrade of the physical layer modulation techniques inevitable. Orthogonal Frequency Division Multiple Access (OFDMA) which utilizes multicarrier modulation to provide higher data rates with the capability of flexible resource allocation, although has widely been used in current wireless systems and standards, seems not to be the best candidate for cognitive radio systems. Filter Bank based Multi-Carrier (FBMC) is an evolutionary scheme with some advantages over the widely-used OFDM multicarrier technique. In this paper, we focus on the total throughput improvement of a cognitive radio network using FBMC modulation. Along with this modulation scheme, we propose a novel uplink radio resource allocation algorithm in which fairness issue is also considered. Moreover, the average throughput of the proposed FBMC based cognitive radio is compared to a conventional OFDM system in order to illustrate the efficiency of using FBMC in future cognitive radio systems. Simulation results show that in comparison with the state of the art two algorithms (namely, Shaat and Wang) our proposed algorithm achieves higher throughputs and a better fairness for cognitive radio applications.

Diagnostic Value of Protein Ki67 (MIB-1) in Atypical Pap Smears of Postmenopausal Women

Fakhrjou, Ashraf,Dastranj-Tabrizi, Ali,Ghojazadeh, Morteza,Ghorashi, Sona,Velayati, Atefeh,Piri, Reza,Vahedi, Amir,Sayyah-Melli, Manizhe,Smaeili, Heydar-Ali,Bonakdari, Amir,Halimi, Monireh,Naghavi-Beh Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.8

Background: Atrophic epithelium of cervix sampled from postmenopausal women may mimic high-grade cervical intraepithelial neoplasia in Papanicolaou-stained (Pap) smears. Ki-67 (MIB-1) protein presents on proliferating cells, and percentage of cells with positive nuclei provides a reliable tool for rapid evaluation of the growth fraction. The aim of this study was to determine the diagnostic value of protein Ki67 staining in atypical pap smears of postmenopausal women. Methods: In a case-control setting, pap smears of 75 women with an atypical pap smear (case group) and 75 with normal pap smears (controls) were obtained before and after estrogen treatment. Afterward, samples were exposed to the monoclonal antibody Ki-67 (MIB-1) and the immunohistochemically demonstrated Ki-67+ cells were compared. Results: Mean ages of cases and controls were $60.4{\pm}4.5$ and $59.9{\pm}4.3$ years respectively (P=0.50). There was one (2.7%) positive Ki-67 specimen in the case group, without any positive Ki-67 specimen in the control group (P=0.50). Conclusions: Measurement of proliferative activity index in Pap smears restrained with MIB1 is a simple, reliable, and cost-effective method for excluding negatives. This would imply that it might allow a substantial reduction of diagnostic estrogen courses and subsequent Pap smears in postmenopausal women with atypical findings.

Optical Simulation and Investigation of the Effect of Hysteresis on the Perovskite Solar Cells

Farhad Jahantigh,S. M. Bagher Ghorashi 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.10

Perovskite solar cells have recently been considered to be an auspicious candidate for the advancement of future photovoltaic research. A power conversion efficiency (PCE) as high as 22% has been reported to be reached, which can be obtained through an inexpensive and high-throughput solution process. Modeling and simulation of these cells can provide deep insights into their fundamental mechanism of performance. In this paper, two different perovskite solar cells are designed by using COMSOL Multiphysics to optimize the thickness of each layer and the overall thickness of the cell. Electric potential, electron and hole concentrations, generation rate, open-circuit voltage, short-circuit current and the output power were calculated. Finally, PCEs of 20.7% and 26.1% were predicted. Afterwards, according to the simulation results, the role of the hole transport layer (HTL) was investigated and the optimum thickness of the perovskite was measured to be 200 nm for both cells. Therefore, the spin coating settings are selected so that a coating with this thickness for cell 1 is deposited. In order to compare the performance of HTM layer, solar cells with a Spiro-OMeTAD HTM and without the HTM layer in their structure were fabricated. According to the obtained photovoltaic properties, the solar cell made with Spiro-OMeTAD has a more favorable open-circuit voltage (VOC), short-circuit current density (JSC), fill factor (FF) and PCE compared to the cell without the HTM layer. Also, hysteresis depends strongly on the perovskite grain size, because large average grain size will lead to an increase in the grain's contact surface area and a decrease in the density of grain boundaries. Finally, according to the results, it was concluded that, in the presence of a hole transport layer, ion transfer was better and ion accumulation was less intense, and therefore, the hysteresis decreases.

Parental Knowledge and Attitudes about Human Papilloma Virus in Iran

Ghojazadeh, Morteza,Naghavi-Behzad, Mohammad,Azar, Zahra Fardi,Saleh, Parviz,Ghorashi, Sona,Pouri, Ali-Asghar Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.12

Infection by human papillomavirus (HPV) is one of common sexually transmitted diseases leading to cervical cancer. Evaluation of parental knowledge and attitudes toward HPV were aims of present study to provide an appropriate method to decrease burden of this infection on society. During this study, 358 parents were assessed for knowledge about HPV and its related disorders. Some 76% of parents had no information about HPV infection and among the informed parents 36% had obtained their information via internet and others from studying medical resources. The average score of mothers information about HPV infection was higher than that of fathers, and also educational level and age had significant impact on knowledge of parents about HPV. Parent knowledge about the hazards of HPV was higher than their knowledge about modes of transmission. Lack of awareness about HPV infection was high in this study, underlining the urgency of education among all adult people in our society.

Preparation and investigation of the physical and chemical properties of clay-based polyacrylamide/Cr (III) hydrogels as a water shut-off agent in oil reservoirs

Farhad Salimi,Mohsen Vafaie Sefti,Khosrow Jarrahian,Majid Rafipoor,Seyyed Saeed Ghorashi 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.6

The effects of clay (montmorillonite and kaolinite) in the hydrogels were investigated on various propertiessuch as syneresis and strength of thermal and salinity situations in one of the southern Iranian oil reservoirs. The X-raydiffraction (XRD) patterns exhibited a significant increase in interplanar spacing between the montmorillonite claylayers, varying from the initial value of 12.43 oA to 19.45 oA, which evidences the intercalation formation. It was revealedthat even increasing of the interlayer spacing due to kaolinite modification had no effect on the clay compositions. Formationwater was used to study the strength of the hydrogel in the presence of ions. The results indicated that 15 wt%increase of kaolinite clay (modified and non-modified) leads to 20% decrease of the hydrogels’ syneresis. The diffusionof polymer chains between the clay layers increased the elastic modulus (G') of the prepared hydrogels with modifiedkaolinite and montmorillonite, where the maximum value of G' was observed in 3 wt% of montmorillonite. Finally,the thermogravimetric analysis (TGA) indicated an increase in the thermal stability of the mentioned hydrogels.