Sharif Digital Repository

Deteriorated land-uses constitute vast portions of the metropolitan areas, being small lots of land, hardly accessible, structurally unstable, and extremely vulnerable to moderate earthquakes. We present the results of a stated preference survey done to support the viability of administering a novel tri-lateral Public–Private Partnership of Build-Operate-Transfer type proposal of Government (G)-Residents (R)-Private Sector Investors (P). In this proposal, the (low income) R in a zone trade their lands for an equivalent value of safe housing built by P next to a newly constructed Bus Rapid Transit line built by G in the same zone, thus a Transit-Oriented Development. P, in return, receives... 

In unreliable supply environments, the strategy of pooling lead time risks by splitting replenishment orders among multiple suppliers simultaneously is an attractive sourcing policy that has captured the attention of academic researchers and corporate managers alike. While various assumptions are considered in the models developed, researchers tend to overlook an important inventory category in order splitting models: deteriorating items. In this paper, we study an order splitting policy for a retailer that sells a deteriorating product. The inventory system is modelled as a continuous review system (s, Q) under stochastic lead time. Demand rate per unit time is assumed to be constant over... 

Inventory management of deteriorating items faces major challenges by uncertain demand, uncertain lead time, perishability, and high customer service level requirements. So, this issue is extremely important in many corporations today. The periodic up-to level policy for deteriorating products under stochastic demand and stochastic lead time is not paid enough attention up to now. In this paper we propose a new approach to study inventory up-to level policy of deteriorating products under normal distributed demand and lead time by considering service level requirements. To model deterioration process, a non-linear increasing holding cost function is considered. After developing the... 

Supply chain sustainability, with economic, environmental, and social values, has gained attention in both academia and industry. For deteriorating and seasonal products, like fresh produce, the issues of timely supply and disposal of the deteriorated products are of great concern. This paper is to develop a possibilistic mathematical model, solved after linearizing the non-linear statements, and to propose a new replenishment policy for a centralized Sustainable Supply Chain (SSC) for deteriorating items. Different transportation vehicle options, which produce various pollution and greenhouse gas (GHG) levels, are considered. Several variables such as the end-customer demand, the partial... 

There is a growing concern, in the last decade, about the environment and social footprint of business operations. The subject of supply chain sustainability, simultaneously considering economic, environment and/or social values, has gained attention in the academia and from the industry. Particularly for deteriorating and seasonal products, such as fresh produce, the issues of timely supply and disposal of the deteriorated products are of high concerns. This research develops a new replenishment policy in a centralized sustainable supply chain for the deteriorating items. The model considers inventory and transportation costs, as well as the environmental and social impacts, with several... 

In this paper, a replacement-repair model is developed to study a warranty servicing policy for a class of multi-state deteriorating and repairable products, based on a computer simulation analysis. In each working state there is a determined probability for transition to each of the subsequent states, given that it has made a transition out of that state. There are two parameters that determine the manufacturer's decision to repair or replace a failed item, assuming that the buyer's claim is valid; the deterioration degree of the item and the length of the residual warranty period. Beside these two parameters, other inputs to the model are: the number of working and failure states, the... 

Wall thickness measurement and deterioration determination of 6 and 10 inch pipes due to corrosion/erosion/pitting was evaluated by using radiographic film density measurements. Special reference blocks were prepared with defined step wall reductions and artificial defects. Gamma radiography with a Ir-192 source was used. A double-wall technique with longitudinal film arrangement was used for this purpose. Formulae were developed from the experiments for numerical calculations. It was observed that this method can determine remaining wall thickness as well as pitting corrosion in insulated and non-insulated pipes with differential and absolute density measurements. The purpose of the work... 

This paper aims to develop a deteriorated bridge maintenance strategy that ensures the safe operation of steel structures and minimizes the total risk. Five common failure modes are considered for the deteriorated bridge: flexure, shear, deflection, fatigue failure for girder, and chloride attack for the concrete deck. Time-dependent and system reliability analyses are carried out to find the probability of failure under these failure modes. Risk-cost optimization is then used to determine the maintenance strategy. This method was applied to a working example. It was found that the developed maintenance strategy can predict when, where, and what to maintain for a bridge to ensure its safe... 

In recent years consumers and legislation have been pushing companies to design their activities in such a way as to reduce negative environmental impacts more and more. It is therefore important to examine the optimization of total supply chain costs and environmental impacts together. However, because of the recycling of deteriorated items, the environmental impacts of deteriorating items are more significant than those of non-deteriorating ones. The objective of this paper is to develop a stochastic mathematical model and to propose a new replenishment policy in a centralized supply chain for deteriorating items. In this model, we consider inventory and transportation costs, as well as... 

Many developed models for deterioration items considered only costs related to inventories. Recently consumers and legislation have pushed companies to design their activities in order to reduce more and more the negative environmental impacts. Thus, it is important to examine the optimization of total supply chain costs and environmental impacts together. However, because of the recycling of the deteriorated items, the environmental impacts of supplying deterioration items are more significant than the non-deterioration products. The objective of this paper is developing a mathematical model and proposing a new replenishment policy in a centralized supply chain for deterioration items. In... 

In the present article, thermal behavior and heat transfer deterioration (HTD) of transcritical methane as well as the fluid state change in regenerative cooling with straight/curved rectangular channels are studied numerically. Simulations are conducted with a finite-volume based CFD solver utilizing reliable turbulence models and thermo-fluidic relations in transcritical conditions. The experimental and numerical results of hydrogen inside a heated tube in the literature are used for validation. The effects of mass flow rate, outlet pressure, wall temperature, surface roughness, and the channel geometry on the thermal behavior of the coolant fluid are studied in detail. According to the... 

The Shrine of Prophet Daniel, located in the south-western part of Iran, represents one of the great examples of the pure brick cultural heritage buildings. This study summarizes the historical background of the shrine building. The structural parts of the building are covered in detail. The existing damages to different parts of the building are classified and the cause of each damage type is elaborated. Several in-situ and laboratory standard tests were carried out to determine the most important material characteristics of the building. Field observations and tests results prove that the building has mostly suffered from the ascending moisture which caused foundation settlement and... 

In this paper we develop two models; the without shortages and the completely backlogging shortages with the price dependant demand rate under time value of money and inflation, finite time horizon and exponentially deterioration rate with the objective of maximizing the present worth of the total system profit. Using the dynamic programming method for each model, we are able to obtain different selling price, order quantity and cycle length for each cycle. We also use a proper numerical example to show accuracy of the solution procedures and to compare the results. This research and its results are unique and have never been concluded before  

Multi-stream Plate-fin heat exchangers (MSPFHEs) are among the most efficient heat exchangers in energy-based industries. They should be carefully designed to have maximum effectiveness and to avoid wasting energy. Flow maldistribution could significantly degrade the performance of heat exchangers. This study presents a novel modeling framework to capture the thermally-induced maldistribution in two-phase MSPFHEs. The developed model is used to show how thermally-induced flow maldistribution affects the performance of the heat exchanger, and some possible modifications are investigated to reduce its consequences. Our case study results show that thermally-induced maldistribution decreases... 

Abstract. Structural collapse is the main concern for the existing structures which are built in the seismic-prone regions. Therefore, the primary goal of the seismic provisions in building codes is to prevent the global collapse. Iran is located in the Alpine-Himalayan belt, and has experienced some of the most destructive earthquakes in the past century. To evaluate the extent to which the Iranian building code provisions meet the abovementioned objective, the authors conducted a detailed assessment of collapse risk on a set of moderate moment resisting Reinforced Concrete (RC) buildings. While many features might affect the seismic performance of the RC structures, this study considers... 

The development and application of inventory models for deteriorating items is one of the main concerns of subject matter experts. The inventory models developed in this field have focused mainly on supply chains under the assumption of constant lead time. In this study, we develop an inventory model for a main class of deteriorating items, namely perishable products, under stochastic lead time assumption. The inventory system is modeled as a continuous review system (r, Q). Demand rate per unit time is assumed to be constant over an infinite planning horizon and the shortages could be backordered completely. For modeling the deterioration process, a non-linear holding cost is considered....