Sharif Digital Repository

Various aspects of land use regression (LUR) models for volatile organic compounds (VOCs) were systematically reviewed. Sixteen studies were identified published between 2002 and 2017. Of these, six were conducted in Canada, five in the USA, two in Spain, and one each in Germany, Italy, and Iran. They were developed for 14 different individual VOCs or groupings: benzene; toluene; ethylbenzene; m-xylene; p-xylene; (m/p)-xylene; o-xylene; total BTEX; 1,3-butadiene; formaldehyde; n-hexane; total hydro carbons; styrene; and acrolein. The models were based on measurements ranging from 22 sites in El Paso (USA) to 179 sites in Tehran (Iran). Only four studies in Rome (Italy), Sabadell (Spain),... 

Magnetic carbon nanotubes (MCNTs) have been widely studied for their potential applications in medicine, diagnosis, cell biology, analytical chemistry, and environmental technology. Introduction of MCNTs paved the way for the emergence of new approaches in nanobiotechnology and biomedicine as a result of their multifarious properties embedded within either the carbon nanotubes (CNTs) or magnetic parts. Numerous preparation techniques exists for functionalizing CNTs with magnetic nanoparticles, and these versatile strategies lay the ground for the generation of novel and versatile systems which are applicable to many industries and biological areas. Here, we review and discuss the recent... 

As Gregory Bateson, the British social scientists, once said "You can't live without an eraser", the process of learning is not a unidirectional way toward accumulation of knowledge, rather, organizations should critically evaluate the value of their knowledge and if necessary, actively forget no-longer-useful knowledge. A brief review of related literature shows that the concept of knowledge active forgetting (KAF) is a crucial aspect of organizational learning and knowledge management. However, many aspects of this topic deserve more attention by researchers. The main gap in the literature seems to be related to the linkage between peculiar aspects of knowledge (such as stickiness, context... 

In this study, the cost function of the defined system is derived first. Then, we prove this function is convex in the system's base stock level. Finally, based on the convexity of the cost function, the optimal solution for the base stock model is determined. For demonstrating the applicability of the proposed method, we resort to solving an example. © 2009 Asian Network for Scientific Information  

Epoxy resins have been used as structural materials since the late 1940s. Despite their desirable properties such as high strength, excellent creep resistance, and good adhesion, they suffer from low fracture energy. Rubber modification as a major toughening approach to overcome the inherent brittleness of epoxy polymers was introduced during the early 1970s. Since then, a large number of investigations have been conducted to elucidate different aspects of rubber-toughened epoxies. The present work is a critical review of the field focusing on the important parameters affecting rubber-toughening. The studies reviewed are classified in five categories including roles of matrix ductility,... 

In this paper, an exact solution procedure is presented for the Weighted Earliness-Tardiness Project Scheduling Problem (WETPSP) with Generalized Precedence Relations (WETPSP-GPR), taking into account the time value of money (WETPSPDC-GPR) and a fixed deadline for the project. The WETPSP-GPR extends the WETPSP to arbitrary minimal and maximal time-lags between the starting and completion times of activities. We present a new depth-first Branch and Bound (B&B) algorithm for an extended form of the problem, in which the time value of money is taken into account by discounting cash flows, and minimum, as well as maximum, time-lags between different activities may be given. The algorithm is... 

We consider a single item, two-level inventory system which consisting of two suppliers and one retailer. Transportation times are constant. The retailer faces Poisson demands and applies continuous (R,Q) policy. Each supplier starts with m initial batches of size Q/2 and places an order in a batch of size Q/2 to an outside source immediately after the retailer's inventory position reaches R+s. In this paper using the idea of the one-for-one ordering policy, we derive the exact value of the expected total cost in the convergent coordinated supply chain. © 2008 IEEE  

The inventory replenishment policy exploited by a supply chain has a principle role in amplification of order variability compared to fluctuations in customers' demands. This phenomenon is known as the bullwhip effect. In this paper, a four echelon supply chain is simulated and the impacts of continuous and periodic review order-up-to policies on the bullwhip effect are examined. Experiments have been conducted to analyze the influence of the lead time in deterministic conditions, and also the variance of demand and lead time in stochastic circumstances on the bullwhip effect and the corresponding cost. It was observed that in low demand and lead time variances, it is more efficient to... 

In this paper we consider a dyadic supply chain consisting of one warehouse and one retailer with an unequal order batch size and information exchange. Transportation times are constant and retailer faces independent Poisson demand. The retailer applies continuous review (R,Q)-policy. The supplier starts with m initial batches (of size Q), and places an order in a batch of size nQ to an outside source immediately after the retailer's inventory position reaches R+s. In this paper using the idea of the onefor- one ordering policy we obtain the exact value of the expected system costs  

In this paper we consider a dyadic supply chain consisting of one warehouse and one retailer with information exchange. We assume that the demand process to the retailer is a Poisson process and transportation times are constant. The retailer applies continuous review (R,Q)-policy. When the retailer's inventory position reaches R+s she sends information about her customer demand and inventory activities to the supplier. The supplier receives this information after a constant time lag. The supplier starts with m initial batches (of size Q), and places an order in a batch of size Q to an outside source immediately after receiving the information from the retailer. In this paper using the idea... 

In this paper we consider a two-level inventory system with one warehouse and one retailer with information exchange. The retailer applies fixed order size continuous review policy. The supplier starts with m initial batches of the same order size of the retailer, and places an order to an outside source immediately after the retailer's inventory position reaches an amount equal to the retailer's order point plus a fixed value s. Transportation times are constant and the retailer faces independent Poisson demand. In a recent paper it was pointed out that the optimal supplier policy in this inventory system is an open question. To obtain the optimal policy for this system, first we find the... 

Among all the rare earth elements, Pr is known to behave as a singularity in the high-Tc families. When high-temperature cuprates are doped with Pr the superconductivity is quenched, and a metal insulator transition occurs. The origin of this behavior, being of fundamental interest, may also shed light on the mechanism of high-temperature superconductivity, since any reasonable theory for this mechanism should explain the behavior of the Pr-based system. The physical properties and the several theories which have been proposed to describe the anomalous behavior of Pr-doped systems in the normal and superconducting states are reviewed. © 2002 Elsevier Science B.V. All rights reserved