Sharif Digital Repository

In this paper, we study a pricing-inventory model with multiple interdependent products and stochastic demand. In the relevant literature, there are many researches that try to optimize the inventory or price independently and also optimizing joint inventory and pricing problems for single product. But joint optimization of inventory and pricing for multiple interdependent products is relatively new and still there are many potential research gaps in this area. We show that the multiplicative demand form problem, that we develop, is a convex nonlinear programming (NLP) model or is convertible to it. We also provide upper and lower bounds for the additive demand form model  

Linear sampling of sparse vectors via sensing matrices has been a much investigated problem in the past decade. The nonlinear sampling methods, such as quadratic forms are also studied marginally to include undesired effects in data acquisition devices (e.g., Taylor series expansion up to two terms). In this paper, we introduce customized nonlinear sampling techniques that provide possibility of sparse signal recovery. The main advantage of the nonlinear method over the conventional linear schemes is the reduction in the number of required samples to 2k for recovery of k-sparse signals. We also introduce a low-complexity reconstruction method similar to the annihilating filter in the... 

This article concerns the notion of methodology in strategic management of R&D/technology. Though development of new tools and methods has received much attention during the recent decades, attention to understanding methodologies has remained disproportionally low. In this study we distinguish two methodologies that are used in strategic management of R&D/technology: planning methodology and evolutionary learning methodology. We mainly focus on defining and describing the origins, nature, and characteristics of the latter. We propose a framework for methodology selection by investigating context, content, and process factors. Using this framework, we provide supportive evidence for... 

Distributed power generation and the ever-growing load demand have caused fault current levels to exceed the nominal rating of the power system devices, and fault current limiters are more needed. Superconducting fault current limiter (SFCL) forms an important category of current limiters. In this paper, a novel flux-based model for the inductive shield-type high-temperature SFCL is developed based on the Bean model. This model is employed to simulate the SFCL performance in a sample circuit. Utilizing the model, the signal characterization of the limited current is determined. A prototype laboratory scale SFCL has been fabricated with superconducting rings. Yttrium barium copper oxide... 

High-performance supercapacitors that merit superior power and energy densities, as well as long-term cycle durability are always of great significance as a building block of energy storage devices. Herein, an innovative strategy is developed to design hierarchical and unique porous structures of ternary metal sulfide nano-flake decorated porous hydrothermal carbon microspheres. Hierarchical microspheres of ternary zinc-cobalt sulfide nanosheet (NS) decorated biomass derived hydrothermal carbon spheres (HTCSs) are directly employed as the positive supercapacitor electrodes. In addition, composites of pyrolyzed polyaniline nanotubes (PPNTs) and iron oxide, receiving advantages from highly... 

Progression in the renewable energy field is tied to the development of high-performance energy storage devices with superior power and energy densities. Herein, an innovative material design was employed to prepare binder-free nickel-cobalt sulfide (NCS) on niobium pentoxide (Nb2O5)-decorated carbon spheres (CSs). Initially, CSs were directly grown on nickel foam (NF) via a hydrothermal carbonization approach. Core/shell-like NCS@Nb2O5@CS-NF was then synthesized through a hydrothermal process, followed by an electrodeposition process. When employed as an electrode material, NCS@Nb2O5@CS-NF achieved an excellent volumetric capacity of 9300 C L−1 at a current density of 18 A L−1. Later, an... 

The compute-and-forward (CMF) method has shown a great promise as an innovative approach to exploit interference towards achieving higher network throughput. The CMF was primarily introduced by means of information theory tools. Although there have been some recent works discussing different aspects of efficient and practical implementation of CMF, there are still some issues that are not covered. In this study, the authors first introduce a method to decrease the implementation complexity of the CMF method. They then evaluate the exact outage probability of the authors proposed simplified CMF scheme, and hereby provide an upper bound on the outage probability of the optimum CMF in all... 

Synthetic aperture radar (SAR) systems are so popular in aerial imaging because of their high resolution. Ground moving target indication (GMTI) is one of the most challenging problems in this field. The use of multiple antennas in transmit and receive is an innovative idea that can overcome the limitations of SAR systems. In this paper, after modelling the received signal and focusing it, we propose an algorithm for GMTI with the use of compressed sensing. The proposed algorithm has low complexity compared to similar algorithms. Simulation results show that this approach is accurate in estimation of positions and velocities of moving targets. © 2018 IEEE  

Motivation: Why, despite substantial investment in science and technology infrastructure during the last two decades, has Iran performed relatively poorly in terms of innovation and economic output? The investment has been wide-ranging, from the inclusion of science and technology in the National Development Plans to the impressive growth in the number of science and technology parks and incubators. Iran is among the top five countries in terms of science and engineering graduates, and Iran's scientific publications are among the world's fastest-growing. Purpose: This study attempts to discover the reasons for this poor performance despite the investment. Approach and Method: This is a... 

In this study a model is presented to predict the residual strength of composite laminates exposed to the heat flux of fire. This model calculates the number of the damaged laminas considering the charred thickness of the composite laminate and then predicts the overall residual strength of the laminate analyzing each lamina. Charred laminas no longer have their initial properties due to decomposition of their polymer matrix. This model can obtain the damaged thickness by introducing a damage temperature, and solving the energy equation for the thermochemical response of the laminate. The thickness of the charred layer is measured for the laminate after exposure to different heat fluxes and... 

The sparsity and compressibility of finite-dimensional signals are of great interest in fields, such as compressed sensing. The notion of compressibility is also extended to infinite sequences of independent identically distributed or ergodic random variables based on the observed error in their nonlinear $k$ -term approximation. In this paper, we use the entropy measure to study the compressibility of continuous-domain innovation processes (alternatively known as white noise). Specifically, we define such a measure as the entropy limit of the doubly quantized (time and amplitude) process. This provides a tool to compare the compressibility of various innovation processes. It also allows us... 

There are a lot of parameters which are decisive in distribution loss management, such as demand value, energy price, etc. In this paper the cause-and-effect relationships among some of these variables are clearly described. The study demonstrates how a variable in the model will change, if an alteration in one of the other variables occurs. The power system variables considered in this study include energy and loss prices, generation and demand values, distribution loss, distribution system age, number of customers connected to the smart grid, distribution network revenue, and so forth. The smart grid impacts can be studied from two different aspects: 1) the communication infrastructure... 

Machine learning (ML) is generating new opportunities for innovative research in energy economics and finance. We critically review the burgeoning literature dedicated to Energy Economics/Finance applications of ML. Our review identifies applications in areas such as predicting energy prices (e.g. crude oil, natural gas, and power), demand forecasting, risk management, trading strategies, data processing, and analyzing macro/energy trends. We critically review the content (methods and findings) of more than 130 articles published between 2005 and 2018. Our analysis suggests that Support Vector Machine (SVM), Artificial Neural Network (ANN), and Genetic Algorithms (GAs) are among the most... 

Purpose: Different studies have analyzed the relationship between organizational learning (OL) and innovation performance (IP). However, the question of how innovation culture (IC) affects the relationship between OL and IP remains unexplored. This study aims to examine the impact of IC on the relationship between OL and various dimensions of IP, including product, process and objective innovation. Design/methodology/approach: A research model was developed and performed based on the relevant literature in the field of OL, IC and IP. The hypotheses are tested with the data collected from companies operating in an intensive knowledge-based industry. Findings: Based on the results of 625... 

The reliability of power electronic based converters has become increasingly important due to their wide-spread use in industry. An effective method to increase the availability of converters is to use condition monitoring systems for planning scheduled maintenances. This paper provides a method to monitor the condition of IGBTs in a back-to-back converter based on their on-state voltage measurement. Using the proposed system adds limited number of elements to the circuit but can be implemented independent from the converter. Considering the converter topology has made the proposed method applicable for condition monitoring of switches in different back-to-back converters. This advantage... 

We present a sampling theory for a class of binary images with finite rate of innovation (FRI). Every image in our model is the restriction of 1{p le; 0} to the image plane, where 1 denotes the indicator function and p is some real bivariate polynomial. This particularly means that the boundaries in the image form a subset of an algebraic curve with the implicit polynomial p. We show that the image parameters - i.e., the polynomial coefficients'satisfy a set of linear annihilation equations with the coefficients being the image moments. The inherent sensitivity of the moments to noise makes the reconstruction process numerically unstable and narrows the choice of the sampling kernels to... 

One of the new forming world discipline feature is knowledge based innovation. World new discipline, vitality condition is to establish new science and technology and suitable utility from that. Therefore, the new era witness those grand variations in university systems and for more utilization process in national, regional and international economical development. In this context, traditional university variation and conversion to Entrepreneurial University and holding and creating idea and supporting it to transform in final product or service is concerned, which means knowledge-based entrepreneurship. Thus, this university can develop knowledge-based staff and has nontraditional processes... 

The literature on technological capabilities has highlighted the effects of innovation on economic growth. However, further analysis is required to determine how innovation factors affect the technological catch-up process outputs. The main purpose of the present study is therefore to determine the impacts of innovation-building factors (i.e., technological and social capabilities) on the innovation outputs. The role of market and innovation financing in technological catch-up has also been investigated. Partial least squares structural equation modeling has been employed to identify which factors have the most significant effects on this process. We have extracted twelve hypotheses from the... 

We propose an innovative design for metallic slit-groove nanostructure to increase the propagation intensity of a unidirectional Surface Plasmon Polariton (SPP) light beam. Our idea is based on the combination of the concept of unidirectional plasmonic wave propagation in a metallic slit-groove nanostructure and the well-known hybrid modes of a hybrid metal-dielectric waveguide. Our results demonstrate that the hybrid structure results in up to 5 times enhancement in the SPP beam intensity relative to the conventional design of slit-groove nanostructure. This new design of SPP based nano source can be applied in many applications including nano photonic devices  

The American Association of State Highway and Transportation Officials (AASHTO) and Federal Highway Administration (FHWA) encourage the use of various Accelerated Bridge Construction (ABC) strategies, which can help reduce onsite construction time, minimize traffic and environmental impacts, improve work zone safety, and deliver longer lasting and more durable bridges. ABC approaches include the application of technical innovations and management techniques. The decision to use ABC must be made on a project-by-project basis as each bridge location is unique, and factors constraining each project are different. Toward this end, FHWA developed a qualitative decision making framework called...