Two new species of Chrysis Linnaeus (Hymenoptera, Chrysididae) from Iran

Afrouz Farhad,Paolo Rosa,Ali Asghar Talebi,Yaghoub Fathipour,Hamidreza Hajiqanbar 한국응용곤충학회 2019 Journal of Asia-Pacific Entomology Vol.22 No.4

The Iranian species in the Chrysis pulchella and C. varidens species groups are investigated. Six species are recognized, two of which are described for the first time: Chrysis gamberoonensis Farhad, Rosa and Talebi sp. nov. and Chrysis brunneamarginata Farhad, Rosa and Talebi sp. nov.. Chrysis gamberoonensis Farhad, Rosa and Talebi sp. nov. belongs to the C. pulchella group and is recognizable within this species group by its unique blue body coloration, scattered mesosoma punctures, polished pit row with elongated pits, and a small median tooth on the lateral edge of metasomal tergum 3. Chrysis brunneamarginata Farhad, Rosa and Talebi sp. nov. belongs to the C. varidens group and is recognizable by the usually colorless apical rim of metasomal tergum 3, and the unique shape of the anterior corners of the scutellum which are enlarged, thickened and directed backward covering the axillary trough. Dichotomous keys and distributional data for Iranian species included in these species groups are provided. Chrysis schwarzi Linsenmaier, 1968 is raised to species rank. The number of Iranian Chrysis species and subspecies is raised to 122.

Statistical calibration of safety factors for flexural stiffness of composite columns

Farhad Aslani,Ryan Lloyd,Brian Uy,Won-Hee Kang,Stephen Hicks 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.1

Composite column design is strongly influenced by the computation of the critical buckling load, which is very sensitive to the effective flexural stiffness (EI) of the column. Because of this, the behaviour of a composite column under lateral loading and its response to deflection is largely determined by the EI of the member. Thus, prediction models used for composite member design should accurately mirror this behaviour. However, EI varies due to several design parameters, and the implementation of high-strength materials, which are not considered by the current composite design codes of practice. The reliability of the design methods from six codes of practice (i.e., AS 5100, AS/NZS 2327, Eurocode 4, AISC 2010, ACI 318, and AIJ) for composite columns is studied in this paper. Also, the reliability of these codes of practice against a serviceability limit state criterion are estimated based on the combined use of the test-based statistical procedure proposed by Johnson and Huang (1997) and Monte Carlo simulations. The composite columns database includes 100 tests of circular concrete-filled tubes, rectangular concrete-filled tubes, and concrete-encased steel composite columns. A summary of the reliability analysis procedure and the evaluated reliability indices are provided. The reasons for the reliability analysis results are discussed to provide useful insight and supporting information for a possible revision of available codes of practice.

Modeling of Pt-Sn/γ-Al2O3 deactivation in propane dehydrogenation with oxygenated additives

Farhad Khorasheh,Abolfazl Samavati,Moslem Fattahi 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.1

A reduction in catalyst activity with time-on-stream and formation of side products are the major problems associated with catalytic propane dehydrogenation. Coke formation on the catalyst surface is the most important cause for catalyst deactivation. Experiments have indicated that the presence of very small amounts of oxygenated additives such as water can reduce the amount of coke accumulated on the catalyst surface and enhance catalyst activity. Addition of water beyond an optimum level, however, would result in a loss of activity due to sintering of catalyst. Propane dehydrogenation over a Pt-Sn/γ-Al2O3 catalyst in the temperature range of 575 to 620 oC was investigated in the presence of small amounts of water added to the feed. A monolayer-multilayer mechanism was used to model the coke growth kinetics. Coke deposition and catalyst sintering were considered in a catalyst deactivation model to explain the observed optimum level in the amounts of water added to the feed. The model predictions for both propane conversion and coke formation with time-on-stream were in good agreement with experimental data.

A New Ethernet Switching Based on Extended Shortcut Switching Strategy

Farhad Faghani,Ghasem Mirjalily 대한전자공학회 2017 대한전자공학회 학술대회 Vol.2017 No.1

Spanning Tree Protocol is a layer-2 IEEE approved standard that provides a loop-free forwarding topology in Ethernet networks. In STP some links are active and the others are blocked. This guarantees only one route between each node pair. As in STP there is not any traffic engineering mechanism for load balancing, these results in uneven load distribution and bottlenecks especially close to the Root. In this paper we propose a new forwarding strategy based on using Shortcut Switching Strategy and hierarchical addressing and we will show we can achieve better results in comparison with STP.

Short term bond shear stress and cracking control of reinforced self-compacting concrete one way slabs under flexural loading

Farhad Aslani,Shami Nejadi,Bijan Samali 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.13 No.6

Fibre-reinforced self-compacting concrete (FRSCC) is a high-performance building material that combines positive aspects of fresh properties of self-compacting concrete (SCC) with improved characteristics of hardened concrete as a result of fibre addition. To produce SCC, either the constituent materials or the corresponding mix proportions may notably differ from the conventional concrete (CC). These modifications besides enhance the concrete fresh properties affect the hardened properties of the concrete. Therefore, it is vital to investigate whether all the assumed hypotheses about CC are also valid for SCC structures. In the present paper, the experimental results of short-term flexural load tests on eight reinforced SCC and FRSCC specimens slabs are presented. For this purpose, four SCC mixes – two plain SCC, two steel, two polypropylene, and two hybrid FRSCC slab specimens – are considered in the test program. The tests are conducted to study the development of SCC and FRSCC flexural cracking under increasing short-term loads from first cracking through to flexural failure. The achieved experimental results give the SCC and FRSCC slabs bond shear stresses for short-term crack width calculation. Therefore, the adopted bond shear stress for each mix slab is presented in this study. Crack width, crack patterns, deflections at mid-span, steel strains and concrete surface strains at the steel levels were recorded at each load increment in the post-cracking range.

Does Financial Integration Matter for Financial Development? Evidence from the East Asian and Pacific Region

Farhad Taghizadeh-Hesary,Nguyet Thi Minh Phi,Hanh Hoang Thi Hong,Vu Tuan Chu 세종대학교 경제통합연구소 2019 Journal of Economic Integration Vol.34 No.4

This paper assesses the impact of financial integration on financial development and establishes thresholds for materializing gains of financial advances from financial globalization using a sample of 34 countries from the East Asian and Pacific region. Following the approaches of Kose et al. (2011) and Asongu and De Moor (2016), we test non-linearity within the financial openness and financial development nexus through semi-parametric ordinary least-squares regression, and then, we develop threshold dynamics models. According to our findings, the effect of financial integration on financial development significantly changes across different financial inflows. When using external debt as a proxy for financial openness, there exists a robust significant inverted U-shaped relationship between financial integration and financial development. The empirical findings also suggest that the financial integration-development nexus is contingent on the level of trade openness, national income, and institutional quality. The results are robust to different measures of financial development and integration, the inclusion of other determinants of financial development, and considerations of endogeneity.

Conditional monitoring of moisture content in a fluidized bed dryer by the acoustic emission signature

Farhad Karimi,Rahmat Sotudeh-Gharebagh,Reza Zarghami,Mojgan Abbasi,Navid Mostoufi 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.5

Wetted rice particles were dried in a fluidized bed and the corresponding passive acoustic emissions signals (AES) were recorded at a given frequency to study the drying phenomena and bed hydrodynamic changes as well. The results show that the end time of the constant rate zone and the end of the falling rate can be determined from the variation of standard deviation and kurtosis of AES, respectively. Frequency domain analysis was also used to quantify the moisture content of solids. For this end, the original signal was decomposed into ten sub-signals, and it was found that the energy of the 4th sub-signal can be correlated with the moisture content. The results show that the acoustic emission measurement is applicable as a practical method for on-line condition monitoring of drying process in fluidized bed dryers.

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.

Two-year survival analysis of twisted wire fixed retainer versus spiral wire and fiber-reinforced composite retainers

Farhad Sobouti,Vahid Rakhshan,Mahdi Gholamrezaei Saravi,Ali Zamanian,Mahsa Shariati 대한치과교정학회 2016 대한치과교정학회지 Vol.46 No.2

Objective: Traditional retainers (both metal and fiber-reinforced composite [FRC]) have limitations, and a retainer made from more flexible ligature wires might be advantageous. We aimed to compare an experimental design with two traditional retainers. Methods: In this prospective preliminary clinical trial, 150 post-treatment patients were enrolled and randomly divided into three groups of 50 patients each to receive mandibular canine-to-canine retainers made of FRC, flexible spiral wire (FSW), and twisted wire (TW). The patients were monitored monthly. The time at which the first signs of breakage/debonding were detected was recorded. The success rates of the retainers were compared using chi-squared, Kaplan-Meier, and Cox proportional-hazard regression analyses (α = 0.05). Results: In total, 42 patients in the FRC group, 41 in the FSW group, and 45 in the TW group completed the study. The 2-year failure rates were 35.7% in the FRC group, 26.8% in the FSW group, and 17.8% in the TW group. These rates differed insignificantly (chi-squared p = 0.167). According to the Kaplan-Meier analysis, failure occurred at 19.95 months in the FRC group, 21.37 months in the FSW group, and 22.36 months in the TW group. The differences between the survival rates in the three groups were not significant (Cox regression p = 0.146). Conclusions: Although the failure rate of the experimental retainer was two times lower than that of the FRC retainer, the difference was not statistically significant. The experimental TW retainer was successful, and larger studies are warranted to verify these results.

Long-term flexural cracking control of reinforced self- compacting concrete one way slabs with and without fibres

Farhad Aslani,Shami Nejadi,Bijan Samali 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.14 No.4

In this study experimental result of a total of eight SCC and FRSCC slabs with the same cross-section were monitored for up to 240 days to measure the time-dependent development of cracking and deformations under service loads are presented. For this purpose, four SCC mixes are considered in the test program. This study aimed to compare SCC and FRSCC experimental results with conventional concrete experimental results. The steel strains within the high moment regions, the concrete surface strains at thetensile steel level, deflection at the mid-span, crack widths and crack spacing were recorded throughout the testing period. Experimental results show that hybrid fibre reinforced SCC slabs demonstrated minimum instantaneous and time-dependent crack widths and steel fibre reinforced SCC slabs presented minimum final deflection.