Hamed Masoumi

Bio: Hamed Masoumi is an academic researcher from Semnan University. The author has contributed to research in topics: Radiation protection & Thermal spraying. The author has an hindex of 7, co-authored 17 publications receiving 257 citations. Previous affiliations of Hamed Masoumi include University of California, San Diego & Isfahan University of Technology.

Identification and Classification of Plastic Resins using Near Infrared Reflectance Spectroscopy

Abstract: In this paper, an automated system is presented for identification and separation of plastic resins based on near infrared (NIR) reflectance spectroscopy. For identification and separation among resins, a \"Two-Filter\" identification method is proposed that is capable to distinguish among polyethylene terephthalate (PET), high density polyethylene (HDPE), polyvinyl chloride (PVC), polypropylene (PP) and polystyrene (PS). Through surveying effects of parameters such as surface contamination, sample thickness, label and cap existence, it was obvious that the \"Two-Filter\" method has a high efficiency in identification of resins. It is shown that accurate identification and separation of five major resins can be obtained through calculating the relative reflectance at two wavelengths in the NIR region. Keywords—Identification, Near Infrared, Plastic, Separation, Spectroscopy

Effect of Grinding on the Residual Stress and Adhesion Strength of HVOF Thermally Sprayed WC–10Co–4Cr Coating

Abstract: In carbide cermet coatings, such as WC–Co–Cr, the surface roughness of the sprayed workpiece is much more than the acceptable values for various industrial demands. Thus, the surface of the carbide cermet coatings is to be ground appropriately to obtain suitable surface finish. However, the grinding may change the properties of coating. In this study, effects of the grinding process on the porosity content, residual stress, microhardness, and adhesion and cohesion strength of the high-velocity oxy-fuel WC–10Co–4Cr coatings are investigated. For this purpose, the grinding experiments have been performed on a surface grinder using a diamond wheel (resin bond) under different grinding parameters, such as table feed rate, cutting speed, and depth of cut. The investigations of residual stress state and adhesion properties were carried out using the X-ray diffraction and interfacial indentation test methods, respectively. The results indicated that the coating's porosity content increased after grinding due to ...

Grinding Force, Specific Energy and Material Removal Mechanism in Grinding of HVOF-Sprayed WC–Co–Cr Coating

Abstract: The present study applies the machining approach and other analysis techniques to investigate the material removal behavior during surface grinding of high-velocity oxy-fuel (HVOF) thermally sprayed WC–10Co–4Cr coating using a resin-bonded diamond wheel. The basic grinding factors such as force ratio, specific material removal rate, maximum undeformed chip thickness, and specific grinding energy have been investigated and discussed. The mathematical models containing linear terms and interactions of the first-order have been used to investigate the effect of the grinding parameters on the grinding force. The results have shown that both tangential and normal grinding forces depend not only on the depth of cut, feed rate, and cutting speed, but also on the depth of cut and feed rate interaction. Scanning electron microscopy (SEM) examination of the ground surface has revealed that the mechanism of material removal presents both brittle fracture and ductile flow modes. Considering the effect of the process ...

Stabilizing and dispersing methods of TiO2 nanoparticles in biological studies

Abstract: TiO 2 nanoparticles (NPs) might be considered as the most important photosensitizer due to high photocatalytic and sonocatalytic efficiency, low toxicity, excellent biocompatibility, low cost and high chemical stability. TiO 2 -NPs normally tend to aggregate in physiological medium and which results to decreased cell viability and inducing expression of stress-related genes. Thus dispersion and stability of TiO 2 NPs should be considered in biological application. This paper deals on various dispersing methods such as ultrasonication, electrostatic, steric electrosteric stabilization that suppress agglomeration and stabilizes the dispersed NPs in aqueous medium.Sonication breaks up agglomerated NPs in a solvent. The results showed that probe sonication performs better than bath sonication in dispersing TiO 2 agglomerates, but sonication couldn’t prevent long term aggregation of nanoparticles and in order to form stable dispersions, it is not enough to break nanoparticles apart. Agglomerated NPs can be separated by overcoming the weaker attractive forces by electrostatic, steric or electrosteric interactions. Electrostatic stabilization takes place when charges accumulate at the surface of particles. At values of potential more than 30 mV or less than -30 mV no agglomeration occurs. Ionic strength and pH influence on electrostatic stabilization; when pH is far from the isoelectric point, agglomeration is suppressed. In a sterically stabilized dispersion large molecules such as polymers, surfactants and biomolecules, adsorbed on to the surface of particles suppress re-agglomeration. PEG is a hydrophilic polymer, non-toxic and non-immunogenic, and has favorable pharmacokinetics and tissue distribution. PEGylation of NPs not only prevents agglomeration, but also enhances their biocompatibility and increases the in vivo circulation time.

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON