Sharif Digital Repository

The rational design of composite catalysts is critically essential for electrochemical water splitting. Here, we report on a novel hierarchical composite that comprises NiFeSe2 nanoparticles and NiCo2O4 nanoflakes supported on nickel foam (NF) as an efficient electrocatalyst for the hydrogen evolution reaction (HER). The conjunction of the NiFeSe2 nanoparticles and NiCo2O4 nanoflakes introduces a new synergistic effect for the HER, resulting in an improved NiCo2O4 catalyst. The as-prepared NiFeSe2/NiCo2O4/NF electrode exhibited an enhanced HER activity, with a low overpotential of 83 mV at a current density of 10 mA cm−2, a low Tafel slope of 45 mV dec−1, and an excellent long-term... 

We present a novel deep convolutional neural network (DCNN) model for predicting human behavior in repeated games. The model is the first deep neural network presented on repeated games that is able to be trained on games with arbitrary size of payoff matrices. Our neural network takes the players’ payoff matrices and the history of the play as input, and outputs the predicted action picked by the first player in the next round. To evaluate the model’s performance, we apply it to some experimental games played by humans and measure the rate of correctly predicted actions. The results show that our model obtains an average prediction accuracy of about 63% across all the studied games, which... 

Rational function-based models have proved to be very efficient for accurate frequency-dependent modeling of power system components. These models are able to characterize the components terminal behaviours (analysing the admittance matrix) for nodal analysis. This provides a fast convergence and inherent stability to the solution routine of the model. This work presents a general framework for interfacing the dynamic phasor method to the rational models. That would be promising for the electromagnetic transient analysis (under harmonic distortion), in the frequency domain. Therefore, Y-element rational pole-residue models (employing the vector fitting method) are developed. Moreover, the... 

Laser drilling is a well-established manufacturing process utilised to produce holes in various aeroengine components. This research presents an experimental investigation on the effects of laser drilling process parameters on productivity (material removal rate), hole quality (hole taper) and drilling cost. Single-pulse drilling was employed to drill a thin-walled Inconel 718 superalloy plate of 1 mm thickness using pulsed Nd:YAG laser. The experiments were designed using Box-Behnken statistical approach to investigate the impacts of pulse energy, pulse duration, gas pressure and gas flow rate on the selected responses. Multi-objective optimisation was performed using response surface... 

The new generations of bioenhancement technologies and traditional Virtue Theory both try to make a meaningful connection between the improvement of human states and characteristics on one hand, and attainment to the good life, on the other. Considering the main elements of virtuousness in Farabi’s thought—namely rational inquiry and deliberative insights, alongside volitional discipline within various social contexts, one can conclude that although the trajectories of enhancement technologies—be they in the field of genetic engineering, neurostimulation technologies, or pharmacology—do not in themselves satisfy the constitutive determinants of virtuousness, they function as having both... 

In this paper, a modified frequency control model is proposed, where the demand response (DR) control loop is added to the traditional load frequency control (LFC) model to improve the frequency regulation of the power system. One of the main obstacles for using DR in the frequency regulation is communication delay which exists in transferring data from control center to appliances. To overcome this issue, an adaptive delay compensator (ADC) is used in order to compensate the communication delay in the control loop. In this regard, a weighted combination of several vertex compensators, whose weights are updated according to the measured delay, is employed. Generating the phase lead is the... 

The new generations of bioenhancement technologies and traditional Virtue Theory both try to make a meaningful connection between the improvement of human states and characteristics on one hand, and attainment to the good life, on the other. Considering the main elements of virtuousness in Farabi’s thought—namely rational inquiry and deliberative insights, alongside volitional discipline within various social contexts, one can conclude that although the trajectories of enhancement technologies—be they in the field of genetic engineering, neurostimulation technologies, or pharmacology—do not in themselves satisfy the constitutive determinants of virtuousness, they function as having both... 

In this article Pitt’s and Sharif’s models of technology are discussed. These models are based on two different conceptions of technology, which are technology as “instrument” and as “making use of instrument.” Sharif considers technology as a collection of empowering tools, including technoware, humanware, infoware and orgaware. On the other hand, Pitt sees technology as “humanity at work.” Based on his definition, Pitt proposes a model of technology with three components; first-order transformation, second-order transformation, and the assessment of feedback mechanism. In this article this model will be explained and criticized. After that, Sharif’s model is criticized in the light of... 

The exergoeconomic analysis is a powerful tool to study an energy system and provide rational decision-making for it. This paper is aimed at exergoeconomic optimization and sensitivity analysis evaluation of the results of a commercial parabolic trough collector (PTC). First, an analysis of optical, thermal, exergy, and economic equations of the PTC system is presented. Then, the objective function and variables are optimized through MATLAB software using the hybrid algorithm code. The objective function as the exergy loss rate is a combination of exergy loss and system cost. The evaluation of the results has been carried out considering the radiation intensity in different months of the... 

We consider a mechanism design problem for the joint flow control and multipath routing in informationally decentralized networks with strategic agents. Based on a surrogate optimization approach, we propose an incentive mechanism that strongly implements the social-welfare maximizing outcome in Nash equilibria. This mechanism possesses several other desirable properties, including individual rationality and budget balance at equilibrium. More importantly, in contrast to the existing literature on the network resource allocation mechanisms, the proposed mechanism is dynamically stable, meaning that the Nash equilibrium (NE) of the game induced by the mechanism can be learned by the agents in... 

In this paper we address the electromagnetic (EM) wave scattering from human body in millimeter-wave (MMW) band and 5G networks, where human body can be considered as an electrically large object. The complicated geometry of human body is accurately modeled using non-uniform rational B-spline (NURBS) surfaces as a thin dielectric slab with permittivity of human skin. Physical optics (PO) approximation is used to formulate the scattering problem. To solve highly oscillatory PO integrals, triangular boundary-rectangular mesh (TBRM) algorithm is exploited. This algorithm provides frequency-independent solution for PO integrals and allows frequency-independent meshing of the human body surface.... 

This paper introduces a shock-wave-detection technique based on the schlieren imaging for continuum and rarefied-gas flows. The scheme is applicable for any existing two-dimensional flowfields obtained by experimental or numerical approaches. A Gaussian distribution for a schlieren function within the shock-wave region is considered. This enables the authors to access any desired locations through the shock (e.g., shock center, or leading- and trailing-edge locations). The bow shock-wave profile is described via a rational function, which could be employed for the estimation of shock angle. The relation between pre- and postshock flow properties along the shock wave with a high resolution... 

Damage detection of a full-scale nine-story reinforced concrete building is investigated using forced vibration test (FVT). The building was the former Civil and Architecture Department of Tohoku University located in Sendai Japan. Earthquake resistance elements of this building were severely damaged in 1978 Miyagi-Ken Oki earthquake and the building was retrofitted on 2001. FVT was performed on the structure before and after retrofitting with same sensor arrangement. Using data acquired from sensors, system identification was performed using rational fraction polynomial and the damage assessment (detection and location) was done by modal assurance criterion and its derivatives. The results... 

Closed-form enough-accurate Green's function for wave-propagation modeling in a rectangular 2-D room is presented using the characteristic Green's function technique. This Green's function is first developed in an integral form. Then, its spatial-domain closed form is obtained using three fast methods. In the first method, the integral is computed by the stationary phase method. In the second one, the integral is computed analytically by expanding the integrand into a complex exponential series. In the third method, the integrand is approximated by a series of rational functions and the integral is computed using Cauchy's residue theorem. The results of these three methods are studied and... 

A novel method to compute guided mode reflectivity from optical waveguide end-facet is presented in this paper. First, rational function fitting method (RFFM) is applied in characteristic Green’s function (CGF) technique to find an approximate closed-form analytic expression for spatial Green’s function of abruptly truncated slab waveguide. Then, derived closed-form relation along with the exact results of spatial Green’s function, obtained by full wave solution, are incorporated in an efficient optimization problem. The fast Newton reflective method with trust region algorithm are utilized for optimized reflection coefficients of guided modes. The main advantage of the proposed CGF-RFFM... 

Over the last decades, several approaches have been proposed in the literature to incorporate users' perceptions of travel costs, their bounded rationality, and risk-taking behaviors into network equilibrium modeling for traffic assignment problem. While theoretically advanced, these models often suffer from high complexity and computational cost and often involve parameters that are difficult to estimate. This study proposes an alternative approach where users' imprecise perceptions of travel times are endogenously constructed as fuzzy sets based on the probability distributions of random link travel times. Two decision rules are proposed accordingly to account for users' heterogeneous... 

An efficient method for computation of surface wave (SW) reflectivity and coupling in an abruptly ended planar layered waveguide is presented. Using characteristic Green's function (CGF) technique, the original structure is approximated by a separable structure. Then by applying rational function fitting method (RFFM) a uniform and closed-form expression of spatial Green's function for separable structure is derived. Having a full wave solution of the original structure, an optimization problem is defined to find the reflection coefficients of SW modes. Unlike the previous presented CGF based method called CGF-complex images (CI), CGF-RFFM leads to easy incorporation of radiation modes... 

In this paper, we propose a frequency-independent method for calculation of scattered electromagnetic (EM) fields by the human body in millimeter-wave (MMW) band. The surface of the body is accurately modeled by non-uniform rational B-spline (NURBS) surfaces and is illuminated by a plane wave. The scattered EM fields are formulated by physical optics (PO) approximation. This approximation yields PO surface highly oscillatory integrals that are solved by numerical steepest descent path (NSDP) method, frequency-independently. This paper provides an efficient and accurate method for considering human body in indoor propagation, surveillance and medical imaging, and detection of human body by... 

This paper considers dynamic pricing in a production system with a single product which is demanded by several customer classes. We seek the structure of the optimal policy assuming m available prices and n demand classes that differ based on the lost sales cost they impose on the system. The assumption of different available prices leads to dynamic pricing structure and the assumption of several demand classes leads to rationing which is proposed in the literature of revenue management. We found that an optimal policy structure exists for this combined problem. The optimal policy has a threshold form which lower thresholds are related to the rationing decision and upper thresholds are... 

A novel method for computation of modal reflectivity at optical waveguide end-facet is presented. The method is based on the characteristic Green's function (CGF) technique. Using separability assumption of the structure and rational function fitting method (RFFM), a closed-form field expression is derived for optical planar waveguide. The uniform derived expression consists of discrete and continuous spectrum contributions which denotes guided and radiation modes effects respectively. An optimization problem is then defined to calculate the exact reflection coefficients at the end-facet for all extracted poles obtained from rational function fitting step. The proposed CGF-RFFM-optimization...