EXPERIMENTAL STUDY OF REGENERATIVE ROTATIONAL DAMPER IN LOW FREQUENCIES

Ali Amini,Özgür Ekici,Kenan Yakut 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.1

This study focuses on energy harvesting from vehicle suspension by employing a regenerative rotational shock absorber. Designing, manufacturing and testing of a prototype device is done step by step to provide a useful manual for researchers. The prototype damper was especially designed for low frequency applications. A rack-pinion mechanism was proposed to transform linear motion to rotational one. Unidirectional motion was realized by using a new combination of bearings and gear chain mechanism. This mechanical rectifier was coupled to light weight gear box with high reduction factor. Experimental studies were conducted in laboratory by utilizing a damper testing device. Excitation vibration motion on prototype was in constant amplitude (25 mm) and at variable low frequencies (0.16, 0.32 and 0.48 Hz). Additionally, different resistances were tested as an external load for electric generator (0.66 ~ 10.4 Ω). Generated voltage and power in different case studies were presented. The maximum power was found to be 35 W and the maximum performance achieved was 34.36 %. The range of calculated damping coefficient is in between 4800 Ns/m and 16000 Ns/m that is convenient for passenger and commercial vehicles.

Creeping flow of Herschel-Bulkley fluids in collapsible channels: A numerical study

Ali Amini,Amir Saman Eghtesad,Kayvan Sadeghy 한국유변학회 2016 Korea-Australia rheology journal Vol.28 No.4

In this paper, the steady flow of a viscoplastic fluid is modeled in a planar channel equipped with a deformable segment in the middle of an otherwise rigid plate. The fluid is assumed to obey the Herschel-Bulkley model which accounts for both the yield stress and the shear-thinning behavior of physiological fluids such as blood. To accommodate the large deformations of the flexible segment, it is assumed to obey the twoparameter Mooney-Rivlin hyperelastic model. The so-called fluid-structure interaction problem is then solved numerically, under creeping-flow conditions, using the finite element package, COMSOL. It is found that the yield stress leads to a larger wall deformation and a higher pressure drop as compared with Newtonian fluids. This behavior is predicted to intensify if the fluid is shear-thinning. That is, for a given yield stress, the pressure drop and the wall deformation both increase with an increase in the degree of the fluid's shear-thinning behavior.

Seismic vulnerability macrozonation map of SMRFs located in Tehran via reliability framework

Ali Amini,Mehdi Kia,Mahmoud Bayat 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.78 No.3

This paper, by applying a reliability-based framework, develops seismic vulnerability macrozonation maps for Tehran, the capital and one of the most earthquake-vulnerable city of Iran. Seismic performance assessment of 3-, 4- and 5- story steel moment resisting frames (SMRFs), designed according to ASCE/SEI 41-17 and Iranian Code of Practice for Seismic Resistant Design of Buildings (2800 Standard), is investigated in terms of overall maximum inter-story drift ratio (MIDR) and unit repair cost ratio which is hereafter known as “damage ratio”. To this end, Tehran city is first meshed into a network of 66 points to numerically locate low- to mid-rise SMRFs. Active faults around Tehran are next modeled explicitly. Two different combination of faults, based on available seismological data, are then developed to explore the impact of choosing a proper seismic scenario. In addition, soil effect is exclusively addressed. After building analytical models, reliability methods in combination with structure-specific probabilistic models are applied to predict demand and damage ratio of structures in a cost-effective paradigm. Due to capability of proposed methodology incorporating both aleatory and epistemic uncertainties explicitly, this framework which is centered on the regional demand and damage ratio estimation via structure-specific characteristics can efficiently pave the way for decision makers to find the most vulnerable area in a regional scale. This technical basis can also be adapted to any other structures which the demand and/or damage ratio prediction models are developed.

NUMERICAL SOLUTION OF STOCHASTIC DIFFERENTIAL EQUATION CORRESPONDING TO CONTINUOUS DISTRIBUTIONS

Amini, Mohammad,Soheili, Ali Reza,Allahdadi, Mahdi Korean Mathematical Society 2011 대한수학회논문집 Vol.26 No.4

We obtain special type of differential equations which their solution are random variable with known continuous density function. Stochastic differential equations (SDE) of continuous distributions are determined by the Fokker-Planck theorem. We approximate solution of differential equation with numerical methods such as: the Euler-Maruyama and ten stages explicit Runge-Kutta method, and analysis error prediction statistically. Numerical results, show the performance of the Rung-Kutta method with respect to the Euler-Maruyama. The exponential two parameters, exponential, normal, uniform, beta, gamma and Parreto distributions are considered in this paper.

The Effects of Blackcurrant and Raspberry Consumption on Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Ali Nikparast,Fatemeh Sheikhhossein,Mohammad Reza Amini,Sogand Tavakoli,Azita Hekmatdoost 한국임상영양학회 2023 Clinical Nutrition Research Vol.12 No.1

A systematic review and meta-analysis were designed to summarize studies conducted on the effects of raspberry and blackcurrant consumption on blood pressure (BP). Eligible studies were detected by searching numerous five online databases including PubMed, Scopus, Web of Science, Cochrane Library, and Google Scholar, until December 17, 2022. We pooled the mean difference and its 95% confidence interval (CI) by applying a random-effects model. Overall, the impact of raspberry and blackcurrant on BP was reported in ten randomized controlled trials (RCTs) (420 subjects). Pooled analysis of six clinical trials revealed that raspberry consumption has no significant reduction in systolic blood pressure (SBP) (weighted mean differences [WMDs], −1.42; 95% CI, −3.27 to 0.87; p = 0.224) and diastolic blood pressure (DBP) (WMD, −0.53; 95% CI, −1.77 to 0.71; p = 0.401), in comparison with placebo. Moreover, pooled analysis of four clinical trials indicated that blackcurrant consumption did not reduce SBP (WMD, −1.46; 95% CI, −6.62 to 3.7; p = 0.579), and DBP (WMD, −2.09; 95% CI, -4.38 to 0.20; p = 0.07). Raspberry and blackcurrant consumption elicited no significant reductions in BP. More accurate RCTs are required to clarify the impact of raspberry and blackcurrant intake on BP.

Accumulation of myeloid lineage cells is mapping out liver fibrosis post injury: a targetable lesion using Ketanserin

Saeid Amini-Nik,Ali-Reza Sadri,Li Diao,Cassandra Belo,Marc G. Jeschke 생화학분자생물학회 2018 Experimental and molecular medicine Vol.50 No.-

Liver fibrosis is problematic after persistent injury. However, little is known about its response to an acute insult. Accumulation of myeloid lineage cells contributes into the promotion and resolution of inflammation and fibrosis. Using Cre-transgenic mice that specifically mark myeloid lineage cells with EYFP and burn as a model of acute systemic injury, we investigated the role of myeloid lineage cells in the liver after acute injury. Our data show that thermal injury in mice (30% total body surface area) induces fibrosis predominantly around portal venules whereas myeloid cells are enriched throughout the liver. The fibrosis peaks around 1–2 weeks post injury and resolves by week 3. Ablating myeloid cells led to lower fibrosis. Through FACS sorting, we isolated myeloid lineage cells (EYFP +ve cells) from injured animals and from the control uninjured animals and subjected the extracted RNA from these cells to microarray analysis. Microarray analysis revealed an inflammatory signature for EYFP +ve cells isolated from injured animals in comparison with control cells. Moreover, it showed modulation of components of the serotonin (5-HT) pathway in myeloid cells. Antagonizing the 5HT2A/2C receptor decreased fibrosis in thermally injured mice by skewing macrophages away from their pro-fibrotic phenotype. Macrophages conditioned with Ketanserin showed a lower profibrotic phenotype in a co-culture system with mesenchymal cells. There is a spatiotemporal pattern in liver fibrosis post-thermal injury, which is associated with the influx of myeloid cells. Treating mice with a 5HT2A/2C receptor antagonist promotes an anti-fibrotic effect, through modulating the phenotype of macrophages.

A porous multifunctional and magnetic layered graphene oxide/3D mesoporous MOF nanocomposite for rapid adsorption of uranium(VI) from aqueous solutions

Asma Amini,Mostafa Khajeh,Ali Reza Oveisi,Saba Daliran,Mansour Ghaffari-Moghaddam,Hojat Samareh Delarami 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.93 No.-

A novel adsorbent, GO/Fe3O4/OPO3H2/PCN-222, was successfully synthesized via graphene oxide (GO)modification with magnetic particles, phosphorous-containing groups, and a mesoporous Zr-MOF, PCN-222 (PCN stands for Porous Coordination Network), respectively, to give the nominal composite. The laststep was through a solvent-assisted ligand incorporation technique. Morphological, structural, andphysicochemical properties of the hybrid material was assessed by FT-IR, PXRD, SEM/EDX, BET surfacearea, VSM, TGA/DSC, UV–vis DRS, and ICP-OES analyses. This solid was then used for dispersive solidphase extraction of uranium ions dissolved in water. Several parameters including pH of solution,extraction and desorption times, amount of adsorbent, and type and concentration of elution solventwere investigated and optimized. The maximum adsorption capacity of adsorbent was found to be416.7 mg g 1 (pH, 6.2; amount of adsorbent, 5.0 mg; extraction time, 3.0 min) beyond what wasachievable with the individual components. In addition, various coordination modes between themultifunctional adsorbent and uranyl ions were investigated by DFT calculations in details, revealingsome favorable non-covalent cation–p interaction and strong binding of free-base porphyrin, carboxyland phosphorous-containing groups to the uranium ions. Under optimized conditions, highdetermination coefficient (R2 = 0.9994) was obtained and limit of detection and relative standarddeviation were found 0.9 mg L 1 and 2.7%, respectively

LES simulations of wind-induced pressure on the floor system underside of elevated buildings

Mehrshad Amini,Ali M. Memari 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.33 No.5

Recent hurricanes have shown that coastal elevated houses are still vulnerable to wind-induced damage, mostly to envelope systems. This paper discusses the performance of elevated houses against hurricane wind loads, particularly wind flow characteristics and the distribution of the peak pressure coefficient (Cp_min) corresponding to the underside of the floor system. Computational fluid dynamics (CFD) analysis was utilized to investigate the effect of interior piers and the wind direction (0 ° ,45° , and 90° ) on the distribution and the magnitude of Cp_min. The CFD results show that the distribution of Cp_min and its maximum value are dependent on pier distribution (e.g., pier location and spacing) and wind direction. The distribution of Cp_min for the 90° wind direction is more similar to the 0 ° wind direction, but the leeward parts of the floor system are exposed to higher negative pressures. The maximum of Cp_min belongs to the 45° wind direction, which occurs at the windward edge and behind the interior pier due to recirculation zones and subsequent vortices. The results of this study indicate that current design standards and provisions need to be updated to include proper design requirements for the floor system, particularly around piers, to help reduce direct/indirect wind-induced damage to elevated houses in coastal areas.

The role of cuscutain-propeptide inhibitor in haustoria parasitism and enhanced resistance to dodder in transgenic alfalfa expressing this propeptide

Massoume Amini,Saify Nabiabad Haida,Ali Deljou 한국식물생명공학회 2018 Plant biotechnology reports Vol.12 No.3

Cuscutain is a cysteine protease produced by dodder (the most important weeds of alfalfa) that is essential for the development and penetration of the haustoria in host. The propeptide subunit of cuscutain has a specific inhibitory function and inhibits the enzymatic activity of the cuscutain. In this study, we introduced the gene encoding the propeptide segment of the cuscutain (signal peptide-less inhibitor) into alfalfa and investigated its roles in parasitism and the alfalfa resistance to C. reflexa. Results demonstrated that cuscutain is mainly expressed in haustoria and the expression of propeptide in transgenic alfalfa plants effectively inhibited cuscutain enzyme activity and consequently interrupted haustoria development at the pathogenic stage. Digitate cells of haustoria could not differentiate into the xylem and phloem hyphae in dodder grown on transgenic alfalfa. Dodder development on transgenic alfalfa lines showed an overall reduction in fecundity and vigor due to imperfect attachment of haustoria. Morphology, nodule development and biomass of transgenic plants indicate that the inhibitory transgene exhibits exquisite specificity for cuscutain enzyme and by expression of the inhibitor in transgenic plants, there was no obvious adverse effect on them. The increased development and growth of dodder-challenged alfalfa transgenic plants compared to controls, showed the efficacy of propeptide in dodder control.

Host-synthesized cysteine protease-specific inhibitor disrupts Cuscuta campestris parasitism in tomato

Massoume Amini,Haidar Saify Nabiabad,Ali Deljou 한국식물생명공학회 2017 Plant biotechnology reports Vol.11 No.5

Dodder (Cuscuta campestris) is one of the most important pests of tomato causing severe losses in yield. Cuscutain is a pre-pro-protein produced by dodder that has a cysteine proteinase function essential for normal development of the haustoria and parasitism, which involves the secretion and activation of cuscutain cysteine protease in the host plant tissue. The propeptide subunit of this enzyme has an inhibitory function and restricts the enzymatic activity of cuscutain. Here, we transformed the inhibitory propeptide segment of this enzyme into tomato and examined the tomato resistance to C. campestris. We demonstrate the expression of inhibitory propeptide in transgenic plants and find that it effectively interrupted cuscutain enzyme activity and haustoria development at the endophytic stage. Mature haustoria infecting transgenic hosts showed defects in searching hyphae development and these structures were not elongate, and in most cases no functional haustoria were formed due to inhibitor expression in the transgenic plants after prehaustoria contact. Dodder grown on transgenic lines showed an overall reduction in vigor and fecundity due to defective attachment of haustoria. The increased growth of dodder-challenged transgenic plants relative to controls, demonstrates the efficacy of cysteine protease inhibition in parasite plant control.