Sharif Digital Repository

We present the results of 14 nights of I-band photometric monitoring of the nearby brown dwarf binary, ϵ Indi Ba and Bb. Observations were acquired over 2 months, with a total of close to 42 h of coverage at a typically high cadence of 1.4 min. At a separation of just 0.7 arcsec, we do not resolve the individual components, and so effectively treat the binary as if it were a single object. However, ϵ Indi Ba (spectral type T1) is the brightest known T-type brown dwarf, and is expected to dominate the photometric signal. We typically find no strong variability associated with the target during each individual night of observing, but see significant changes in mean brightness – by as much as... 

This paper presents the results obtained and the deductions made from a series of microstructural studies and mechanical tests involving gray cast iron which was sand cast using a variety of modules. The effect of cooling rate on the primary dendrite arm spacing (DAS), secondary dendrite arm spacing (SDAS), thickness of ferrite-cementite layer (λe) and the hardness (HB) were evaluated. Results show that the both DAS and SDAS and also λe are highly dependent on the cooling rate, and they decreases as the cooling rate increases. More attempts were also done to correlate the HB with DAS, SDAS and λe. It was found that HB increases as DAS, SDAS and λe decreases  

In this work the SOLA-VOF method was used to solve the Navier-Stokes equations and track the free surface. For modeling the turbulence phenomena in the mold filling κ-ε model was used. In this method solving domain was discreted to three regions includes: laminar sub layer, boundary layer and internal region. The simulation results were shown to be in a good agreement with the experimental results  

In this paper, the shear deformation behavior of A286 Iron-based superalloy was studied with an emphasis on the influence of η phase on shear strength. The η (Ni3Ti phase precipitates at high temperature heat treatment or during services at the expense of gamma prime phase. According to the microstructural features, no evidences of η phase were found at 650 and 720°C. η phase precipitated at 780 and 840°C and the amount of it increased with an increase the time and temperature. Because of using the alloy as fasteners, investigation of shear properties and the influence of η phase on it are indispensable. The shear strength of the alloy with different volume fractions of η was examined. It... 

Herein we report a new organocatalyst for the asymmetric Michael addition of nitroalkanes to α,β-unsaturated aldehydes. This catalyst incorporates a basic imidazole group in addition to the secondary amine responsible for activation of the α,β-unsaturated carbonyl compounds via iminium ion formation. The new organocatalyst is capable of catalyzing the enantioselective carbon-carbon bond formation with a high degree of enantiocontrol providing products in enantiomeric excesses of up to 92% and yields of up to to 91 %. These results constitute the best results so far reported for organocatalyzed Michael additions of nitroalkanes to α,β-unsaturated aldehydes, and provide proof of principle that... 

Spiro thio-oxindoles are prepared in situ by the reaction of the corresponding aldehydes and thio-oxindoles in a straightforward, environmentally friendly, highly efficient and simple procedure. The reaction took place in water with no catalyst added. This one-pot reaction afforded regio- and diastereoselective products in high yields (61-93%)  

Accurate and early detection of anomalies in peripheral white blood cells plays a crucial role in the evaluation of well-being in individuals and the diagnosis and prognosis of hematologic diseases. For example, some blood disorders and immune system-related diseases are diagnosed by the differential count of white blood cells, which is one of the common laboratory tests. Data is one of the most important ingredients in the development and testing of many commercial and successful automatic or semi-automatic systems. To this end, this study introduces a free access dataset of normal peripheral white blood cells called Raabin-WBC containing about 40,000 images of white blood cells and color... 

Linear silicone rubber and polyethylene alloy produced from extrusion-injecting process will be present in separate phases. While samples are mixed with 1% dicumylperoxide, DCP, and injected in extruder, an alloy is almost formed. In addition, when the samples containing silicon rubber with vinyl group are mixed with polyethylene and passed in the vicinity of electron beam, a similar reaction occurs, as confirmed from FTIR spectrum. The water contact angles for the samples has been listed in the article. Furthermore, the crystallinity of samples produced via electron beam method is more than that obtained from peroxide method. On the other hand, the tensile strengths of produced samples via... 

The present work deals with a novel approach for grafting a sol-gel based sorbent, using diazonium salts for preparation of an unbreakable capillary microextraction (CME) device in on-line combination with high performance liquid chromatography (HPLC). The use of diazonium salts modifier allowed all types of metallic and non-metallic substrates to be used without any limitation. Substrates including copper, brass, stainless steel and polytetrafluoroethylene (PTFE) were chosen to be functionalized by chemical or electrochemical reduction of 4-amino phenyl acetic acid. Then, 3-(trimethoxysilyl)propylamine (3TMSPA) was selected as the precursor and the only reagent for preparation of the... 

An optimal soft multiple-input multiple-output (MIMO) detector is proposed with linear complexity for a general spatial multiplexing system with two transmitting symbols and NR 2 receiving antennas. The computational complexity of the proposed scheme is independent of the operating signal-to-noise ratio and grows linearly with the constellation order. It provides the soft maximum-likelihood solution using an efficient log-likelihood ratio calculation method, avoiding the exhaustive search on all the candidate nodes. Moreover, an efficient pipelined hardware implementation of the detection algorithm is proposed, which is fabricated and fully tested in a 130-nm CMOS technology. Operating at...