Sharif Digital Repository

Microstructural characteristics and mechanical properties of a friction stir welded cast aluminum bronze (Cu-9Al-1Fe), produced by a sand casting method, have been investigated at tool rotation of 850-1500 rpm and traverse speed of 50-100 mm/min. Refinement of the primary coarse cast microstructure in the base metal was seen after friction stir welding. Microstructure of the stir zone was characterized in four distinct areas of non-isometric fine grains while a significant grain growth was noticed in some of the areas. Conditions of grain growth are defined with high heat input intensity and low heat transfer capability. The grain size was observed to decrease after FSW, resulting in a... 

An efficient, green, novel and rapid vortex-assisted dispersive solid-phase extraction (VADSPE) technique was used for the preconcentration and determination of trace levels of Cu2+ followed by flame atomic absorption spectrometry. Graphene oxide (GO) was synthesized from graphite and then modified by pectic acid (poly-d-galacturonic acid, PA) to synthesize the pectic acid–graphene oxide (PA-GO) nanocomposite. The Fourier transform infrared spectrophotometry, field emission scanning electron microcopy, energy-dispersive X-ray spectroscopy and X-ray diffraction analysis were used to characterize the synthesized GO-PA nanocomposite. By using VADSPE technique, PA-GO was used as an adsorbent for... 

The present contribution is devoted to develop multivariate analytical figures of merit (AFOMs) as a new metric for evaluation of quantitative measurements using comprehensive two-dimensional gas chromatography–mass spectrometry (GC × GC–MS). In this regard, new definition of sensitivity (SEN) is extended to GC × GC–MS data and then, other multivariate AFOMs including analytical SEN (γ), selectivity (SEL) and limit of detection (LOD) are calculated. Also, two frequently used second- and third-order calibration algorithms of multivariate curve resolution-alternating least squares (MCR-ALS) as representative of multi-set methods and parallel factor analysis (PARAFAC) as representative of... 

Most sulfide oxidizing bioreactors are based on pure cultures or artificial mixes of microorganisms with strict requirements for growth, which make the system unstable and do not guarantee their long term performance. The ultimate goal of this study is to develop a natural mix of chemotrophic bacteria that may be applied anaerobically for the treatment of sour gas. Activated sludge from local municipal wastewater treatment plant that was maintained in endogenous anaerobic conditions for one year was used in this study. Total suspended solids (TSS) and volatile suspended solids (VSS) of the sludge was 22 gl-1 and 14.3 gl-1, respectively. A glass culture vessel had a volume of 0.65 L was used... 

Building envelope is the sole interface with outdoors that can lie in the level of integrating control strategies to enhance occupant’s comfort and building performance. However, in the literature, there is still a lack of multi-purpose control strategies which can balance diverse and antagonistic aspects of occupant comfort while keeping the building energy consumption under control. Therefore, this research proposed an integrated simulation-based workflow using EnergyPlus and Python-based package, OpyPlus, to adjust a roller shade for single occupied office space in a hot and arid climate. The developed system aims to improve both occupant’s visual and thermal comfort considering daylight... 

A pH-responsive drug delivery system based on core shell structure of mesoporous silica nanoparticle (MSN) and chitosan-PEG copolymer was prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and high-resolution transmission microscope (HR-TEM) techniques. In order to improve compatibility MSN and drug, mesoporous nanosilica was modified by 3-aminopropyl triethoxysilane. The release of erythromycin (a macrolide antibiotic) as a model drug was investigated in two pHs, 7.4 and 5.5  

A systematic change of HZSM-5 (HZ5) as a catalyst of the methanol to aromatics (MTA) reaction was undertaken by employing a fixed-bed tubular-type reactor under ambient pressure, applying a weight hourly space velocity (WHSV) of 2 h-1 at 375 °C, as the first report on the application of low-Si/Al-ratio alkaline-[Mo,Na]-HZSM-5 in the MTA process. To characterize the surface and textural properties of the catalysts, powder X-ray diffraction (PXRD), nitrogen adsorption/desorption, temperature-programmed desorption of ammonia (NH3-TPD), pyridine-infrared spectroscopy (Py-IR), thermogravimetric analysis (TGA), and energy-dispersive X-ray (EDX) methods were employed. Gas chromatography (GC) and... 

An n × n matrix A is said to be silver if, for i = 1,2,...,n, each symbol in {1,2,...,2n - 1} appears either in the ith row or the ith column of A. The 38th International Mathematical Olympiad asked whether a silver matrix exists with n = 1997. More generally, a silver cube is a triple (K n d , I, c) where I is a maximum independent set in a Cartesian power of the complete graph K n , and c : V(K n d)→ {1,2,...,d(n-1)+1} is a vertex colouring where, for ν ∈ I, the closed neighbourhood N[ν] sees every colour. Silver cubes are related to codes, dominating sets, and those with n a prime power are also related to finite geometry. We present here algebraic constructions, small examples, and a... 

The main problem with airway segmentation methods which significantly influences their accuracy is leakage into the extra-luminal regions due to thinness of the airway wall during the process of segmentation. This phenomenon potentially makes large regions of lungparenchyma to be wrongly identified as airways. A solution to this problem in the previous methods was based on leak detection followed by reducing leakage during the segmentation process. This has been dealt with adjusting the segmentation parameters and performing the re-segmentation process on the pre-segmented area. This makes the algorithm very exhaustive and more dependent on the user interaction. The method presented here is...