Experimental Study on Mechanical Properties of Cement-Stabilized Soil Blended with Crushed Stone Waste

Mohsen Salehi,Meysam Bayat,Mohsen Saadat,Masoud Nasri 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.6

Waste generated by the processing of natural stone poses environmental and economic problems. One promising use for stone waste is soil stabilization. In this paper, a number of tests including unconfined compressive strength (UCS) and California bearing ratio (CBR) of crushed stone were performed to study the effect of curing time, soaked and unsoaked conditions and freeze-thaw cycles on the geotechnical characteristics of cement-stabilized specimens. The results indicate that crushed stone waste can be combined with cement as a stabilizer to improve soil properties. Also the optimum moisture content (OMC) and maximum dry density (MDD) are dependent on the cement content and almost independent of the crushed stone waste content. The CBR increased significantly as the crushed stone waste and cement contents increased under both soaked and unsoaked conditions, but these had little effect on the UCS at curing times of less than 14 days. Cement-stabilized specimens with 10% crushed stone waste showed a significant increase in UCS. The CBR and UCS of unsoaked specimens were higher than for soaked specimens at different crushed stone waste and cement contents. The CBR and UCS values increased with an increase in curing time. However, the curing time had a more obvious effect on UCS than on CBR.

Identification and Prioritization of the Driving Factors of Labor Productivity in the Melli Bank: Iranian Scenario

Mostafa Bahrami,Mahdi Salehi,Mohsen Akbarzadeh,Alireza Morsali 한국유통과학회 2013 The Journal of Industrial Distribution & Business( Vol.4 No.1

Purpose - Labor productivity is extremely important to the profitability and competitive advantage of organizations that provide services to customers, such as banks. This study investigates the factors driving labor productivity in Iran’s Melli Bank. Research design, data, methodology - Five managerial, psychosocial, cultural, and individual factors are identified and their relative importance for labor productivity prioritized using AHP. The required data are then collected through a questionnaire designed for a pairwise comparison of the driving factors of labor productivity and their subcategories. Results - The study outcomes reveal that the managerial and individual factors are the most important. Specifically, the most important factors in increasing labor productivity in the branches of Melli Bank are having a competent supervisor, promotion opportunities, fair working conditions, conscientiousness, the right tools, and a correspondence between skills and work. Conclusions - Implementing AHP using Expert Choice software revealed that, among the driving factors of labor productivity (i.e., managerial, psychosocial, cultural, environmental, and personal), managerial factors were considered the most important by the respondents.

Doubly conditional moment closure modelling for HCCI with temperature inhomogeneities

Salehi, Fatemeh,Talei, Mohsen,Hawkes, Evatt R.,Bhagatwala, Ankit,Chen, Jacqueline H.,Yoo, Chun Sang,Kook, Sanghoon Elsevier 2017 Proceedings of the Combustion Institute Vol.36 No.3

<P><B>Abstract</B></P> <P>This paper presents a doubly conditional moment closure (DCMC) as an <I>a posteriori</I> predictive modelling tool for ignition of mixtures with large thermal stratification in homogeneous charge compression ignition (HCCI) conditions. Double conditioning is applied on enthalpy and its dissipation rate. The performance of the DCMC model is evaluated using a number of previously reported direct numerical simulations (DNSs) with various fuels. The DNSs modelled ignition of various lean homogeneous mixtures with a high level of temperature inhomogeneities. The selected cases exhibit a prevalence of deflagration mode of combustion as opposed to a spontaneous ignition-front mode, which has proven challenging for previous singly CMC. In all simulations, DCMC solver is run in a stand-alone mode with certain terms, such as the probability density functions of enthalpy and dissipation rate, being provided using the DNS input. The DCMC results are in a very good agreement with the DNS data, and are significantly improved compared with a singly conditional moment closure. A set of <I>a posteriori</I> DNS-DCMC tests is also performed to demonstrate importance of various terms in the doubly CMC equations. These tests first reveal that the effects of the cross dissipation and sources of enthalpy and dissipation rate (which lead to convective terms in conditional space) are insignificant and these terms can be safely neglected from the DCMC equations. The significance of this result is that the main unclosed models that would be needed for satisfactory results in a practical simulation of an engine would be the joint probably density function of enthalpy and its dissipation rate and the dissipation rate of dissipation rate.</P>

Feasibility of hydrophobized PES membrane in hybrid MD/FO process using magnetic draw solution

Setareh Salehi,Mohsen Jahanshahi,Majid Peyravi 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.6

The feasibility of PES membrane with hydrophobic property, high glass transition temperature, excellentthermal and chemical stability, with good mechanical properties as porous polymeric support was studied in membranedistillation (MD) process. Several strategies were considered and investigated to decrease membrane wetting bykeeping up salt rejection and also to improve the permeate flux of PES membrane in the MD process. From this pointof view, hydrophobic PMHS polymer with different concentrations was used as a surface coating solution. The morphologyand structure of prepared membranes were evaluated by AFM and FESEM analyses. After coating modification,the salt rejection was increased up to 98% and the contact angle was changed from 65.11o to >100.2o. To increasethe water flux, the effect of feed temperature (55 oC and 75 oC) and draw solution utilization containing magneticnanoparticle (Fe3O4) was investigated. Using draw solution provided a driving force from feed solution to permeateside and increased average permeate flux from 2.9 kg/m2·h to 6.9 kg/m2·h in the 0.06 g/l of draw solute concentration. It improved permeate flux and salt rejection simultaneously.

Application of the differential transformation method and variational iteration method to large deformation of cantilever beams under point load

Pouya Salehi,Hessameddin Yaghoobi,Mohsen Torabi 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.9

Large deflection of a cantilever beam subjected to a tip-concentrated load is governed by a non-linear differential equation. Since it is hard to find exact or closed-form solutions for this non-linear problem, this paper investigates the aforementioned problem via the differential transformation method (DTM) and the variational iteration method (VIM), which are well-known approximate analytical solutions. The mathematical formulation is yielded to a non-linear two-point boundary value problem. In this study, we compare the DTM and VIM results, with those of Adomian decomposition method (ADM) and the established numerical solution obtained by the Richardson extrapolation in order to verify the accuracy of the proposed methods. As an important result, it is depicted from tabulated data that the DTM results are more accurate in comparison with those obtained by the VIM and ADM, which is one of the objectives of this article. Moreover, the effects of dimensionless end point load, α , on the slope of any point along the arc length and the dimensionless vertical and horizontal displacements are illustrated and explained. The results reveal that these methods are very effective and convenient in predicting the solution of such problems, and it is predicted that the DTM and VIM can find a wide application in new engineering problems.

Bulk and rheological properties of polyacrylamide hydrogels for water shutoff treatment

Asefe Mousavi Moghadam,Mohsen Vafaie Sefti,Mahsa Baghban Salehi,Hasan Naderi 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.3

Presenting an optimal hydrogel for water shutoff, based on the bulk and rheological properties, was themain purpose of this research. To determine gelation time, a bottle test was conducted using central composite designmethod with two factors, AN125VLM and Cr(OAc)3, as copolymer and crosslinker, respectively. To select hydrogelwith high strength network, crosslinking density and consistency modulus were also measured. Hence, a hydrogel with26,340 ppm concentration of copolymer, 0.12 ratio of crosslinker/copolymer, maximum value of crosslinking density(1,950) and consistency modulus (31,900 Pa) was selected as the optimal one. To study the gelation time among differentfactors in porous media, rheological experiments were carried out by Plackett-Burman design to screen the eightfactors (NaCl, CaCl2, KCl and MgCl2 concentrations, temperature, pH, sodium lactate and nanoclay). Accordingly,temperature was the most effective factor controlling the gelation time, while pH and other factors had negligible effecton the gelation time of the optimal hydrogel.

Spatial Inequalities in the Incidence of Colorectal Cancer and Associated Factors in the Neighborhoods of Tehran, Iran: Bayesian Spatial Models

Mansori, Kamyar,Solaymani-Dodaran, Masoud,Mosavi-Jarrahi, Alireza,Motlagh, Ali Ganbary,Salehi, Masoud,Delavari, Alireza,Asadi-Lari, Mohsen The Korean Society for Preventive Medicine 2018 Journal of Preventive Medicine and Public Health Vol.51 No.1

Objectives: The aim of this study was to determine the factors associated with the spatial distribution of the incidence of colorectal cancer (CRC) in the neighborhoods of Tehran, Iran using Bayesian spatial models. Methods: This ecological study was implemented in Tehran on the neighborhood level. Socioeconomic variables, risk factors, and health costs were extracted from the Equity Assessment Study conducted in Tehran. The data on CRC incidence were extracted from the Iranian population-based cancer registry. The $Besag-York-Molli{\acute{e}}$ (BYM) model was used to identify factors associated with the spatial distribution of CRC incidence. The software programs OpenBUGS version 3.2.3, ArcGIS 10.3, and GeoDa were used for the analysis. Results: The Moran index was statistically significant for all the variables studied (p<0.05). The BYM model showed that having a women head of household (median standardized incidence ratio [SIR], 1.63; 95% confidence interval [CI], 1.06 to 2.53), living in a rental house (median SIR, 0.82; 95% CI, 0.71 to 0.96), not consuming milk daily (median SIR, 0.71; 95% CI, 0.55 to 0.94) and having greater household health expenditures (median SIR, 1.34; 95% CI, 1.06 to 1.68) were associated with a statistically significant elevation in the SIR of CRC. The median (interquartile range) and mean (standard deviation) values of the SIR of CRC, with the inclusion of all the variables studied in the model, were 0.57 (1.01) and 1.05 (1.31), respectively. Conclusions: Inequality was found in the spatial distribution of CRC incidence in Tehran on the neighborhood level. Paying attention to this inequality and the factors associated with it may be useful for resource allocation and developing preventive strategies in at-risk areas.

Therapeutic Outcomes of Pectoralis Major Muscle Turnover Flap in Mediastinitis

Reza Bagheri,Mohammad Abbasi Tashnizi,Seyed Ziaollah Haghi,Maryam Salehi,Ata’ollah Rajabnejad,Mohsen Hatami Ghale Safa,Mohammad Vejdani 대한흉부외과학회 2015 Journal of Chest Surgery (J Chest Surg) Vol.48 No.4

Background: This study aimed to evaluate the therapeutic results and safety of pectoralis major muscle turnover flaps in the treatment of mediastinitis after coronary artery bypass grafting (CABG) procedures. Methods: Data regarding 33 patients with post-CABG deep sternal wound infections (DSWIs) who underwent pectoralis major muscle turnover flap procedures in the Emam Reza and Ghaem Hospitals of Mashhad, Iran were reviewed in this study. For each patient, age, sex, hospital stay duration, remission, recurrence, and associated morbidity and mortality were evaluated. Results: Of the 2,447 CABG procedures that were carried out during the time period encompassed by our study, DSWIs occurred in 61 patients (2.5%). Of these 61 patients, 33 patients (nine females [27.3%] and 24 males [72.7%]) with an average age of 63±4.54 years underwent pectoralis major muscle turnover flap placement. Symptoms of infection mainly occurred within the first 10 days after surgery (mean, 10.24±13.62 days). The most common risk factor for DSWIs was obesity (n=16, 48.4%) followed by diabetes mellitus (n=13, 39.4%). Bilateral and unilateral pectoralis major muscle turnover flaps were performed in 20 patients (60.6%) and 13 patients (39.4%), respectively. Complete remission was achieved in 25 patients (75.7%), with no recurrence in the follow-up period. Four patients (12.1%) needed reoperation. The mean hospitalization time was 11.69±6.516 days. Four patients (12.1%) died during the course of the study: three due to the postoperative complication of respiratory failure and one due to pulmonary thromboembolism. Conclusion: Pectoralis major muscle turnover flaps are an optimal technique in the treatment of post-CABG mediastinitis. In addition to leading to favorable therapeutic results, this flap is associated with minimal morbidity and mortality, as well as a short hospitalization time.

Spatial Inequalities in the Incidence of Colorectal Cancer and Associated Factors in the Neighborhoods of Tehran, Iran: Bayesian Spatial Models

Kamyar Mansori,Masoud Solaymani-Dodaran,Alireza Mosavi-Jarrahi,Ali Ganbary Motlagh,Masoud Salehi,Alireza Delavari,Mohsen Asadi-Lari 대한예방의학회 2018 Journal of Preventive Medicine and Public Health Vol.51 No.1

Objectives: The aim of this study was to determine the factors associated with the spatial distribution of the incidence of colorectal cancer (CRC) in the neighborhoods of Tehran, Iran using Bayesian spatial models. Methods: This ecological study was implemented in Tehran on the neighborhood level. Socioeconomic variables, risk factors, and health costs were extracted from the Equity Assessment Study conducted in Tehran. The data on CRC incidence were extracted from the Iranian population-based cancer registry. The Besag-York-Mollié (BYM) model was used to identify factors associated with the spatial distribution of CRC incidence. The software programs OpenBUGS version 3.2.3, ArcGIS 10.3, and GeoDa were used for the analysis. Results: The Moran index was statistically significant for all the variables studied (p<0.05). The BYM model showed that having a women head of household (median standardized incidence ratio [SIR], 1.63; 95% confidence interval [CI], 1.06 to 2.53), living in a rental house (median SIR, 0.82; 95% CI, 0.71 to 0.96), not consuming milk daily (median SIR, 0.71; 95% CI, 0.55 to 0.94) and having greater household health expenditures (median SIR, 1.34; 95% CI, 1.06 to 1.68) were associated with a statistically significant elevation in the SIR of CRC. The median (interquartile range) and mean (standard deviation) values of the SIR of CRC, with the inclusion of all the variables studied in the model, were 0.57 (1.01) and 1.05 (1.31), respectively. Conclusions: Inequality was found in the spatial distribution of CRC incidence in Tehran on the neighborhood level. Paying attention to this inequality and the factors associated with it may be useful for resource allocation and developing preventive strategies in atrisk areas.