Sharif Digital Repository

In this paper, first we shall define a list of technology transfer barriers in the biotechnology field through interviews and literature reviews. Next, we shall categorize them into four major categories of technology, and at last introduce all of the hypotheses on the existence of relationship between each part of technology and failure in the technology transfer process. Questionnaires consisting of two parts were created and handed out to all of the specialists and biotechnology idea-holders in the Iranian National Research center of Biotechnology, Lidco Co, Iran Pastor Institute, Biotechnology Department of University of Tehran, etc. Going on, we've evaluated the factors' validity... 

In Industry 4.0, the emergence of new information technology and advanced manufacturing technology (e.g., digital twin, and robot) promotes the flexibility and smartness of manufacturing systems to deal with production task fluctuation. Digital twin-driven manufacturing system with human-robot collaboration is a typical paradigm of intelligent manufacturing. When production task changes, manufacturing system reconfiguration with dynamic opeartion task allocation between operator (human) and robot is a key manner to maintain the production efficiency of intelligent manufacturing system with human-robot collaboration. However, the differences between operator and robot are neglected during... 

Graphitic carbon nitride (g-CN) is a promising metal-free catalyst for environmental remediation. However, its practical applications have been limited due to insufficient solar-light responsivity. Hetero-element doping and the construction of heterostructures, comprised of g-CN and other band-matched semiconductors could be considered to overcome these drawbacks. In the present work, a series of 2D/3D heterostructures comprised of a few layers of boron-doped g-CN (B-CN) anchored on sea urchin-like Bi2S3 (BS) particles (B-CN@BS) were successfully synthesized. The catalytic performances of B-CN@BS composites were assessed for the photo-reduction of Cr(VI) and in-situ generation of H2O2 under... 

A superhydrophobic polystyrene hollow fiber was electrospun around a copper spring collector. This approach led to the construction of a hollow fiber membrane, and the copper spring acted as a scaffold. The characteristic properties of the hollow fiber were studied by scanning electron microscopy. The membrane was used as a probe to transfer the extracting solvent from aquatic media to a gas chromatograph. After performing the liquid–liquid microextraction procedure on 10 mL of water sample by octanol, the whole solution was passed through the prepared polystyrene hollow fiber. Propanol, containing 2 mg/L lindane as the internal standard, was used for desorption and an aliquot of 2 μL of the... 

Silica nanoparticles, which have a broad range of sizes and specific surface features, have been used in many industrial applications. This study was conducted to synthesize monodispersed silica nanoparticles directly from tetraethyl orthosilicate (TEOS) with an alkaline catalyst (NH3) based on the sol–gel process and the Stöber method. A central composite design (CCD) is used to build a second-order (quadratic) model for the response variables without requiring a complete threelevel factorial experiment. The process was then optimized to achieve the minimum particle size with the lowest concentration of TEOS. Dynamic light scattering and scanning electron microscopy were used to analyze the... 

Integrated guidance and control of an elastic flight vehicle based on constrained robust model predictive control is proposed. The design is based on a partial state feedback control law that minimizes a cost function within the framework of linear matrix inequalities. It is shown that the solution of the defined optimization problem stabilizes the nonlinear plant. Nonlinear kinematics and dynamics are taken into account, and internal stability of the closed-loop nonlinear system is guaranteed. The performance and effectiveness of the proposed integrated guidance and control against non-maneuvering and weaving targets are evaluated using computer simulations  

Shortcut design methods can be valuable tools for rapid screening of different separation process alternatives to assess feasibility and determine minimum energy demand. This work presents a variant of the feed angle method (Kraemer et al., 2011), which applies to single- and double-feed reactive distillation columns. The proposed method relies on pinch point analysis and determines the minimum energy demand from the calculation of a tray at the feed pinch. It is fully algorithmic and insensitive to impurities in product specifications. Its validity and performance is illustrated by a variety of case studies covering multi-component and multi-reaction systems, mixtures with potential... 

Integrated guidance and control of an elastic flight vehicle based on constrained robust model predictive control is proposed. The design is based on a partial state feedback control law that minimizes a cost function within the framework of linear matrix inequalities. It is shown that the solution of the defined optimization problem stabilizes the nonlinear plant. Nonlinear kinematics and dynamics are taken into account, and internal stability of the closed-loop nonlinear system is guaranteed. The performance and effectiveness of the proposed integrated guidance and control against non-maneuvering and weaving targets are evaluated using computer simulations  

Co-deposition of Cu(Zn) and graphite powders with size less than 10 μ was studied. Electrocomposite coatings were prepared by means of the conventional electrodeposition (CECD) and the sediment co-deposition (SCD) techniques. Brass electroplating cyanide bath has been selected out of electrodeposition brass. The effect of parameters such as rate of agitation and current density on the composition of electrodeposition brass and also the effect of the concentration of graphite particles in brass bath, air agitation rate on graphite incorporation within brass matrix and deposition efficiency were studied. The wear and friction properties of G-Cu(Zn) composite coatings containing different... 

Double oxide films (hereafter: oxides), inclusions and Fe-rich phases are known to be the most detrimental defects in cast Al-Si-Mg alloys. The effects of these defects on reproducibility of tensile properties in Al-7Si-0.35Mg alloy have been investigated in this study. Four different casting conditions (low oxide-low Fe, high oxide-low Fe, low oxide-high Fe and high oxide-high Fe) were studied. In each case, 30 tensile test samples were prepared by casting in a metallic mold and machining (total of 120 tensile test samples). Results of tensile test were analyzed by Weibull three-parameter and mixture analyses. The microstructure and fracture surface of samples were studied by optical and... 

[No abstract available]  

Energy resources in Iran consist of the fourth largest oil reserves and the second largest natural gas reserves in the world. At present, due to political reasons, the investment trend does not go over well. Based on the Fifth Development Strategy, Iran needs $200 billion of investment in the country's first industry (i.e. oil), and given the objectives of the perspective document, the country needs more than $500 billion investment during the next 15 years. This paper examined Iran's energy status. Afterwards, oil future scenarios which developed by Research center of Iranian parliament, have been analyzed. Then four scenarios that express different modes of production and consumption are... 

Total knee replacement (TKR) surgery is one of the most successful and cost-effective procedures for treating knee injuries performed in orthopedics. However, the knee replacement revision surgery will probably be required after some years. Wear at the contact area between femoral metal component and the polyethylene inserts in TKR is recognized as one of the foremost causes of prosthesis failure and necessity of revision surgery. In the present study, focusing on the patellofemoral joint (PFJ), the wear at the contact area between the patellar and femoral components has been simulated employing the explicit finite element modeling. In this regard, common types of patellar component surface... 

For the production of synthesis gas utilised in Midrex direct reduction plants, catalytic steam/CO2 hydrocarbon reforming in tubular reformer is the major process. Owing to the high heat input through the Midrex reformer tube wall, the endothermic nature of reforming reactions, low mass velocity of feed gas and large tube diameter, the catalyst bed is exposed to considerable axial and radial temperature gradients. These radial concentration and temperature gradients may create local areas with potential for carbon formation. To investigate this phenomenon, a rigorous two-dimensional model is developed for simulating the operation of a Midrex reformer which applies a dual catalyst loading... 

Displacement and strain fields of a screw dislocation in a nanowire are considered within the theory of gradient elasticity. The gradient solution of the corresponding boundary value problem is derived and discussed in detail. It is shown that the dislocation fields do not contain classical jumps and singularities at the dislocation line. The maximum values of the dislocation displacement and elastic strain strongly depend on both the dislocation position and nanowire radius, thus demonstrating a nonclassical size effect. © 2008 Acta Materialia Inc  

A rigorous two-dimensional model is developed for simulating the operation of a less-investigated type steam reformer having a considerably lower operating Reynolds number, higher tube diameter, and non-availability of extra steam in the feed compared with conventional steam reformers. Simulation results show that reasonable predictions can only be achieved when certain correlations for wall to fluid heat transfer equations are applied. In all cases, strong radial temperature gradients inside the reformer tubes have been found. Furthermore, the results show how a certain catalyst loading profile will affect the operation of the reformer. © 2008 Canadian Society for Chemical Engineering  

Using a tight-binding model within the mean-field approximation, the effects of different spin configurations on transport through carbon nanotubes are studied. It is observed that, in the absence of external magnetic field, the mean-field ground states of both semiconducting and metallic nanotubes are antiferromagnetic. As regards electronic/transport properties, a gap opens in the density of states of the metallic tubes for weak applied magnetic fields, and the magnetic field separates the conductance characteristics of spin-up and spin-down carriers. © 2002 Elsevier Science B.V. All rights reserved  

In this paper, an approach to the synthesis of optimal preview control laws for active vehicle suspension has been studied. A basic three-dimensional, seven-degree of freedom car riding model, subjected to two road inputs, is considered. To obtain an enhanced control scheme, the input senses and measures road irregularities, using the contactless sensors fixed on the vehicle front bumper. The suspension systems are optimized, with respect to ride comfort, road holding and suspension rattle space. The performance of active, active and delay and active and preview, are compared with a passive system by numerical simulation in the time domain. The results show that optimal preview control... 

In this work, bending and dynamic analyses of a three-layered functionally graded micro annular plate whit piezomagnetic layers are investigated based on FSD circular plate theory. The micro plate is subjected to magnetic field. It is assumed that the micro annular plate is resting on an orthotropic elastic medium. The stress relations which cooperate both mechanical and magnetic interactions are calculated based on MSGT and the governing equations are extracted through Hamilton’s principles. In order to solve the governing equations of micro annular plate, the numerical Ritz method is applied. After convergence of Ritz solving domain the obtained results are compared and adapted with the... 

Dynamic gait planning for humanoid robots encounters difficulties such as stability, speed, and smoothness. In most of previous studies, joints' trajectories are calculated in 3D Cartesian space, then, introducing boundary conditions and using polynomials, the first and second derivatives of the motion are ensured to be continuous. Then, the stability of the motion is guaranteed using Zero Moment Point (ZMP) stability criterion. In this study, a trajectory planner is presented using the semi-ellipse equations of the motion; the continuity of the derivatives is preserved. Stabilization of motion is attained through using ZMP criterion and 3d inverted pendulum equations in three slope...