Intra-ply, inter-ply and FG hybrid composites based on basalt and poly-ester fibers: Flexural and impact properties

Ehsan Fadayee Fard,Hassan Sharifi,Majid Tehrani,Ehsan Akbari Techno-Press 2023 Advances in materials research Vol.12 No.1

Basalt and poly-ester fibers along with epoxy resin were used to produce inter-ply, intra-ply and functionally gradient hybrid composites. In all of the composites, the relative content of basalt fiber to poly-ester fiber was equal to 50 percent. The flexural and charpy impact properties of the hybrid composites are presented with particular regard to the effects of the hybrid types, stacking sequence of the plies, loading direction and loading speed. The results show that with properly choosing the composition and the stacking sequence of the plies; the inter-ply hybrid composites can achieve better flexural strength and impact absorption energy compared to the intra-ply and functionally gradient composites. The flexural strength and impact absorption energy of the functionally gradient hybrid composites is comparable to, or higher than the intra-ply sample. Also, by increasing the loading speed, the flexural strength increases while the flexural modulus does not have any special trend.

Fluid-structure coupling of concentric double FGM shells with different lengths

Ehsan Moshkelgosha,Ehsan Askari,정경훈,Ali Akbar Shafiee 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.2

The aim of this study is to develop a semi-analytical method to investigate fluid-structure coupling of concentric double shells with different lengths and elastic behaviours. Co-axial shells constitute a cylindrical circular container and a baffle submerged inside the stored fluid. The container shell is made of functionally graded materials with mechanical properties changing through its thickness continuously. The baffle made of steel is fixed along its top edge and submerged inside fluid such that its lower edge freely moves. The developed approach is verified using a commercial finite element computer code. Although the model is presented for a specific case in the present work, it can be generalized to investigate coupling of shellplate structures via fluid. It is shown that the coupling between concentric shells occurs only when they vibrate in a same circumferential mode number, n. It is also revealed that the normalized vibration amplitude of the inner shell is about the same as that of the outer shell, for narrower radial gaps. Moreover, the natural frequencies of the fluid-coupled system gradually decrease and converge to the certain values as the gradient index increases.

Power-aware performance analysis of self-adaptive resource management in IaaS clouds

Ataie, Ehsan,Entezari-Maleki, Reza,Etesami, Sayed Ehsan,Egger, Bernhard,Ardagna, Danilo,Movaghar, Ali North-Holland 2018 Future generations computer systems Vol.86 No.-

<P><B>Abstract</B></P> <P>In this paper, Stochastic Activity Networks (SANs) are used to model and evaluate the performance and power consumption of an Infrastructure-as-a-Service (IaaS) cloud. The proposed SAN model is scalable and flexible, yet encompasses some details of an IaaS cloud, such as Virtual Machine (VM) provisioning, VM multiplexing, and failure/repair behavior of VMs. Using the proposed SAN, a power-aware self-adaptive resource management scheme is presented for IaaS clouds that automatically adjusts the number of powered-on Physical Machines (PMs) regarding variable workloads in different time intervals. The proposed scheme respects user-oriented metrics by avoiding Service Level Agreement (SLA) violations while taking provider-oriented metrics into consideration. The behavior of the proposed scheme is analyzed when the arriving workload changes, and then its performance is compared with two non-adaptive baselines based on diverse performance and power consumption measures defined on the system. A validation of the proposed SAN model and the resource management scheme against an adapted version of the CloudSim framework is also presented.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An analytical model is proposed for Infrastructure-as-a-Service (IaaS) clouds taking several details of such systems into consideration. </LI> <LI> A self-adaptive power-aware and Service Level Agreement (SLA)-aware resource management scheme is presented for cloud systems. </LI> <LI> The presented scheme adjusts the number of powered-on Physical Machines (PMs) according to the input workload. </LI> <LI> A validation of the proposed model and scheme against the CloudSim framework is presented. </LI> </UL> </P>

The tissue expression of MCT3, MCT8, and MCT9 genes in women with breast cancer

Sohrabi Ehsan,Moslemi Masoumeh,Rezaie Ehsan,Nafissi Nahid,Khaledi Mansoor,Afkhami Hamed,Fathi Javad,Zekri Ali 한국유전학회 2021 Genes & Genomics Vol.43 No.9

Background Breast cancer (BC) is a common malignancy with a high mortality rate. Malignant cell transformation is associated with metabolic changes. One group of proteins that are afected is the monocarboxylate transporters (MCTs-SLC16A). The MCTs comprise 14 members, and they play an important role in the growth, proliferation, and metabolism of cancer cells by transporting monocarboxylates such as lactate, pyruvate and thyroid hormones. Objective We aimed to evaluate the expression of MCT3 (SLC16A8), MCT8 (SLC16A2) and MCT9 (SLC16A9) genes in breast cancer samples, comparing to normal adjacent tissues. Methods Forty paired breast cancer tumor samples, the adjacent non-tumor and fve healthy tissues were collected. Three cancer cell lines (MCF-7, MDA-MB-231, and SKBR3) were also analyzed. The expression of SLC16A8, SLC16A2 and SLC16A9 were assessed using quantitative real-time PCR. The relationship between gene expression with the pathological features of the tumors, and the hormone receptors status of the patient’s tumors were also analyzed. Results There was a signifcantly lower expression of the MCT3 gene in tumor samples compared to adjacent normal tissue and healthy samples (p value<0.05). There was a signifcant diference in the expression of all three candidate genes between the BC tissues and normal tissues, and for the, tissues with diferent hormone receptor status and the molecular subtypes. Altered MCT8 and MCT9 gene expression was associated with a reduced survival Conclusion MCT3 expression is signifcantly downregulated in breast cancer tissue. MCT3 may represent a novel therapeutic target in breast cancer patients, or in some hormone receptor subgroups.

Memorial functional foods: a new concept from Bavi tribe

Ehsan Amiri Ardekani,Hossein Askari,Abdolali Mohagheghzadeh 한국식품연구원 2020 Journal of Ethnic Foods Vol.7 No.-

The use of functional foods (FFs) for maintaining health and preventing or treating illnesses—in recent years—has been dramatically increased in the literature. There are available valuable examples of FFs in ethno medicine from different tribes. Ethnic FFs can be valuable resources for developing FFs science, e.g., introducing memorial FFs as an interdisciplinary ethnopharmacological concept. In this paper, ethnic FFs from Bavi tribe (Kohgiluyeh va Boyerahmad province of Iran) have been studied, and their medical potentials are reported. Data gathering was done by interview with Bavi tribe local healers using a questionnaire. Plant materials were collected and identified, and Bavi FFs were prepared according to local procedures. Information of 21 Bavi tribe FFs was collected which are including 20 different plant species.The results showed that most FFs are used to treat chronic diseases including kidney problems like kidney stones, liver disease, neurological complaints, and GI ulcers and are used as lactogogue, while lesser FFs are used to treat acute diseases and symptoms (43%), including nausea and vomiting, common cold, diarrhea, sore throat, and allergy. Most FFs of Bavi tribe are prepared using aromatic plants (75%) responsible for aroma in the final FF. Probably, aromatic FFs increase patient acceptance, without mimicking unpleasant memory of drug recommendation. Plants that are used in FF are mostly perennial (80%) and wild growing (80%), indicating continuous contact of natives and so having memory with such habitant herbals. Treating diseases by homemade FFs which are prepared by well-known aromatic herbals is a routine procedure among natives like the Bavi tribe. Such easily made FFs with well-known taste and flavors which may change the patient’s mood should be studied in a new approach, “memorial FFs”, as a novel opportunity for healthcare and curing.

Fragility assessment of RC-MRFs under concurrent vertical-horizontal seismic action effects

Ehsan Noroozinejad Farsangi,Abbas Ali Tasnimi,Babak Mansouri 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.16 No.1

In this study, structural vulnerability of reinforced concrete moment resisting frames (RC-MRFs) by considering the Iran–specific characteristics is investigated to manage the earthquake risk in terms of multicomponent seismic excitations. Low and medium rise RC-MRFs, which constitute approximately 80-90% of the total buildings stock in Iran, are focused in this fragility–based assessment. The seismic design of 3-12 story RC-MRFs are carried out according to the Iranian Code of Practice for Seismic Resistant Design of Buildings (Standard No. 2800), and the analytical models are formed accordingly in open source nonlinear platforms. Frame structures are categorized in three subclasses according to the specific characteristics of construction practice and the observed seismic performance after major earthquakes in Iran. Both far and near fields’ ground motions have been considered in the fragility estimation. An optimal intensity measure (IM) called Sa, avg and beta probability distribution were used to obtain reliable fragility–based database for earthquake damage and loss estimation of RC buildings stock in urban areas of Iran. Nonlinear incremental dynamic analyses by means of lumped-parameter based structural models have been simulated and performed to extract the fragility curves. Approximate confidence bounds are developed to represent the epistemic uncertainties inherent in the fragility estimations. Consequently, it’s shown that including vertical ground motion in the analysis is highly recommended for reliable seismic assessment of RC buildings.

A Realistic Path Loss Model for Real-time Communication in the Urban Grid Environment for Vehicular Ad hoc Networks

( Ehsan Mostajeran ),( Rafidah Md Noor ),( Mohammad Hossein Anisi ),( Ismail Ahmedy ),( Fawad Ali Khan ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.10

Wireless signal transmission is influenced by environmental effects. These effects have also been challenging for Vehicular Ad hoc Network (VANET) in real-time communication. More specifically, in an urban environment, with high mobility among vehicles, a vehicle’s status from the transmitter can instantly trigger from line of sight to non-line of sight, which may cause loss of real-time communication. In order to overcome this, a deterministic signal propagation model is required, which has less complexity and more feasibility of implementation. Hence, we propose a realistic path loss model which adopts ray tracing technique for VANET in a grid urban environment with less computational complexity. To evaluate the model, it is applied to a vehicular simulation scenario. The results obtained are compared with different path loss models in the same scenario based on path loss value and application layer performance analysis. The proposed path loss model provides higher loss value in dB compared to other models. Nevertheless, the performance of vehicle-vehicle communication, which is evaluated by the packet delivery ratio with different vehicle transmitter density verifies improvement in real-time vehicle-vehicle communication. In conclusion, we present a realistic path loss model that improves vehicle-vehicle wireless real-time communication in the grid urban environment.

Seismic performance of a resilient low-damage base isolation system under combined vertical and horizontal excitations

Ehsan Noroozinejad Farsangi,Abbas Ali Tasnimi,T.Y. Yang,Izuru Takewaki¬,Mohammad Mohammadhasani 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.4

Traditional base isolation systems focus on isolating the seismic response of a structure in the horizontal direction. However, in regions where the vertical earthquake excitation is significant (such as near-fault region), a traditional base-isolated building exhibits a significant vertical vibration. To eliminate this shortcoming, a rocking-isolated system named Telescopic Column (TC) is proposed in this paper. Detailed rocking and isolation mechanism of the TC system is presented. The seismic performance of the TC is compared with the traditional elastomeric bearing (EB) and friction pendulum (FP) base-isolated systems. A 4-storey reinforced concrete moment-resisting frame (RC-MRF) is selected as the reference superstructure. The seismic response of the reference superstructure in terms of column axial forces, base shears, floor accelerations, inter-storey drift ratios (IDR) and collapse margin ratios (CMRs) are evaluated using OpenSees. The results of the nonlinear dynamic analysis subjected to multi-directional earthquake excitations show that the superstructure equipped with the newly proposed TC is more resilient and exhibits a superior response with higher margin of safety against collapse when compared with the same superstructure with the traditional base-isolation (BI) system.

Vibration Performance of Profiled Steel Sheet Dry Board Composite Floor Panel

Ehsan Ahmed,Wan Hamidon Wan Badaruzzaman 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.1

Profiled Steel Sheet Dry Board (PSSDB) composite panel has been proven to be an effective structural system and can be exploited for a variety of structural purposes. As a flooring system, the PSSDB floor carries the out of plane bending and shear mainly in the direction of corrugation of profiled steel sheeting. For such flooring system, human induced vibrations are becoming increasingly vital serviceability and safety issues. In this paper, investigations are carried out on the vibration performances of the PSSDB floor panel. This research is focused mainly on the fundamental frequency of such floor panel. The influence of various board types, board thickness, and connectors spacing on fundamental frequency are evaluated. It was shown that for all the panels considered in this paper, the fundamental frequency was well above 8 Hz and hence, this type of composite floor panel will not be uncomfortable to the occupants of building in terms of vibration.

The influence of some processing conditions on host crystal structure and phosphorescence properties of SrAl2O4:Eu2+, Dy3+ nanoparticle pigments synthesized by combustion technique

Ehsan Shafia,Masoud Bodaghi,Mohammadreza Tahriri 한국물리학회 2010 Current Applied Physics Vol.10 No.2

The spectroscopic and host phase properties of SrAl2O4:Eu2+, Dy3+ phosphors with a series of different initiating combustion temperature, urea concentration as a fuel and critical pH of precursor solution are investigated. The SrAl2O4:Eu2+, Dy3+ nanoparticle pigments were obtained by exothermic combustion process within less than 5 min. The sample that ignited at initiating combustion temperature of 600 ℃exhibits highest intensity emission peak at 517 nm in which the SrAl2O4 host phase has the maximum fraction of monoclinic SrAl2O4 phase. The excitation spectra consist of 240 and 254 nm broad peaks. The experimental results show that the optimum ratio of urea is 2.5 times higher than theoretical quantities for best emission condition of SrAl2O4:Eu2+, Dy3+ phosphor particles. The critical pH was obtained about 5.2. The crystallite size of these pigments is about 40 nm before thermal treatment and 62 nm after thermal treatment, respectively.