Sharif Digital Repository

Passenger cars (PCs) are a major contributor to urban air pollution, greenhouse gas emissions, and energy security challenges in megacities in developing countries because of their high growth potential. Since the PC fleet changes through time, the projection of air pollutant emissions from PCs is essential for effective emission reduction policymaking. However, the extensive amount of data and proper models are required for this purpose that are not available in many developing countries. Hence, this study develops multiple econometric and emission models and integrate them into a framework to simulate the future stock and activity of PCs and projects PCs’ air pollutants and CO2 emissions... 

New concepts and strategies are continually being investigated to meet fuel efficiency targets for new generations of internal combustion engines. Thermal management methods can reduce fuel consumption by up to 4%. One approach for thermal management is a map-controlled thermostat. In the current work, this concept is investigated through a benchmarking approach and a methodology for deriving the response time curve for this type of thermostat. To better explore the benchmarking idea, characteristics of map-controlled thermostats for two different engines are identified, analyzed, and compared. Finally, the effects of two separate map-controlled thermostats on the average fuel consumption of... 

In this research, the effect of alternative fuels and the inlet charged air temperature is numerically investigated on the performance of a turbocharged spark-ignition engine. For this purpose, a one-dimensional engine and turbocharger model is created in an engine simulation and performance analysis software and validated with former experimental results. Then, the model is run with four fuel types, including two gasoline types with different octane numbers and two ethanol–gasoline blend fuels—E25 and E85. In each case, the inlet charged air temperature is changed from cold to hot condition and performance characteristics such as the spark advance timing, brake torque, brake-specific fuel... 

A novel MED-based desalination system for low-grade heat sources with a temperature between 65 °C and 90 °C has been proposed. Low-grade heat-driven desalination systems are of the most important methods for increasing energy efficiency and assisting the environment along with alleviating the water scarcity problem. The new proposed system is known as cascade multi-effect distillation (CMED). It is designed based on multi-step heat extraction from the heat source fluid (HSF). Multi-step heat absorption helps to form two arrays of MED effects and to utilize two boosters to achieve better performance. The advantage of this system is less complexity (for example, lower vapor injection), and... 

Power management strategies play a key role in the design process of hybrid electric vehicles. Electric Assist Control Strategy (EACS) is one of the popular power management strategies for hybrid electric vehicles (HEVs). The present investigation proposes a new framework to advance the EACS. Dynamic Programming method is applied to an HEV model in several drive cycles, and as a result, some optimal operating regions are found. The obtained regions are almost distinct, and consequently, some threshold lines can be defined to separate them. The obtained threshold lines are used to eliminate some parameters of the EACS to reduce its sensitivity to the driving behavior. It is shown that by... 

Feed-in tariff (FiT) is one of the most efficient ways that many governments throughout the world use to stimulate investment in renewable energies (REs) technology. For governments, financial management of the policy could be challenging as it needs a considerable amount of budget to support RE producers during the long remuneration period. In this paper, it has been illuminated that the early growth of REs capacity could be a temporary boost. And the socio-economic structure of the system will backlash the policy if some social mechanisms are not considered. Social tolerance for paying REs tax and potential investors’ trust emanated from budget-related mechanisms -which have rarely been... 

Energy hubs, an important component of future energy networks employing distributed demand-side management, can play a key role in enhancing the efficiency and reliability of power grids. In power grids, energy hub operators need to optimally schedule the consumption, conversion, and storage of available resources based on their own utility functions. In sufficiently large networks, scheduling an individual hub can affect the utility of the other energy hubs. In this paper, the interaction between energy hubs is modeled as a congestion game. Each energy hub operator (player) participates in a dynamic energy pricing market and tries to maximize his/her own payoff when satisfying energy... 

The transportation sector is one of the sustainable development wheels that requires a lot of energy to operate, therefore it is concerned as one of the main factors in greenhouse gas emissions and global warming. In Iran, like rest of the world, the light-duty vehicles are the effective factors in the pollution of the metropolitan cities. Although the management of their fuel consumption is a vital action in decreasing the cost and air pollution, that's inextricable link with the public welfare and the economy of the car manufacturers creates barriers. An accurate analysis concerning the barriers to reducing the fuel consumption can be obtained by using the game theory method in the... 

A cooperative task allocation and search algorithm is proposed to find and localize a group of ground-based moving targets using a group of Unmanned Air Vehicles (UAVs) working in a decentralized manner. It is assumed that targets have RF emissions. By using an algorithm including Global Search (GS), Approach Target (AT), Locate Target (LT), and Target Reacquisition (TR) modes, UAVs cooperatively search the entire parts of a desired area, approach to the detected targets, locate the targets, and search again to find the targets that stop transmitting their RF emissions during the localization process, respectively. In the GS mode, UAVs utilize a cost function to select the best zone for... 

A cooperative task allocation and search algorithm is proposed to find and localize a group of ground-based moving targets using a group of Unmanned Air Vehicles (UAVs) working in a decentralized manner. It is assumed that targets have RF emissions. By using an algorithm including Global Search (GS), Approach Target (AT), Locate Target (LT), and Target Reacquisition (TR) modes, UAVs cooperatively search the entire parts of a desired area, approach to the detected targets, locate the targets, and search again to find the targets that stop transmitting their RF emissions during the localization process, respectively. In the GS mode, UAVs utilize a cost function to select the best zone for... 

Noise emission from vehicles in urban transportation has become of interest for researchers in addition to the engine exhaust gas emissions due to its significant effect on public health. In this work, an optimal energy management strategy is proposed for a hybrid electric vehicle (HEV) by taking the effect of engine noise into account. The engine noise is calculated based on a pressure-based combustion noise model at different operating points of a 1.5 L gasoline engine. The optimal operating points of the engine are defined using the calculated engine noise from in-cylinder pressure data and experimental data of brake specific fuel consumption (FC). A modification on the electric assist... 

Hybrid electric vehicles (HEVs) have been developed as a promising way to decrease the fuel consumption and emissions of conventional vehicles. Although the noise emission of HEVs is generally lower than that of conventional vehicles, it is still an issue, especially in urban transportation. In this paper, a power management strategy is developed to minimize the annoying noise of the engine for an HEV. This is a modified version of the strategy that was originally established based on the speed ratio of continuously variable transmission (CVT) as the control parameter (CVT-based strategy). The engine combustion noise is assessed using the experimental data of the in-cylinder pressure. Also,... 

We estimate the price elasticity of the demand for gasoline smuggling in Iran. For this purpose, we employ a detailed panel of monthly gasoline consumption data from 160 distribution hubs during the period 2005–2014. We apply two different approaches which are diff-in-diff and panel data estimations. The results suggest that the foreign-to-home gasoline price ratios have a significant impact on the time-varying elasticity of demand. This finding supports the hypothesis that an increase in domestic gasoline prices will significantly reduce the demand for smuggling. In addition, as the distance of a region from its closest higher-price neighboring country diminishes, the price elasticity of... 

One way to reduce vehicles' fuel consumption (FC) is to optimize different parts of its powertrain. Among different modern powertrains, continuously variable transmission (CVT) is one of the common types which changes speed ratio between engine and wheels, continuously. Therefore, the CVT allows the engine to operate at its fuel-optimal speed. Due to the limited power transmission capacity and speed ratio range of the CVT, researchers attempted to combine the CVT with a planetary gear train and a fixed ratio mechanism. This mechanism is called infinitely variable transmission (IVT). In this study, a multi-speed gearbox (MSG) is used in the IVT and its impact on the powertrain performance and... 

The development of an efficient hybrid electric vehicle (HEV) platform needs an optimal design of its powertrain layout. This study is concerned with parallel HEVs (PHEVs) equipped with continuous transmission. First, different types of continuous transmissions, including continuously variable transmission (CVT), power-split CVT (PS-CVT) and multi-fixed ratio PS-CVT (MF-CVT), are discussed and their simulation models are presented. Also, various combinations of these continuous transmissions with PHEV configurations (namely, pre-transmission and posttransmission configurations) are introduced. Then, for a given PHEV model, several powertrain layouts resulting from combining the considered... 

Emission factors (EFs) are fundamental, necessary data for air pollution research and scenario implementation. With the vision of generating national EFs of the Iranian transportation system, a portable emission measurement system (PEMS) was used to develop the basic EFs for a statistically significant sample of Iranian gasoline-fueled privately owned light duty vehicles (LDVs) operated in Tehran. A smaller sample size of the same fleet was examined by chassis dynamometer (CD) bag emission measurement tests to quantify the systematic differences between the PEMS and CD methods. The selected fleet was tested over four different routes of uphill highways, flat highways, uphill urban streets,... 

This paper aims to establish a control strategy for parallel hybrid electric vehicles equipped with full-toroidal Continuously Variable Transmission (CVT). First, the advantages of CVT are elucidated. Afterwards, a modified control strategy on the base of Baseline static Control Strategy (BCS) is proposed. Employing this strategy, in some moments, the engine operates in its fuel-optimal point to decrease the vehicle Fuel Consumption (FC). It is demonstrated that the modifications in BCS are applicable using a CVT as the power train. In order to investigate the implemented modification, an optimization on the proposed control strategy and BCS in SC03 driving cycle is accomplished and then,... 

The development of technologies such as micro turbines and gas furnaces has been the major driving force towards integration of electricity and natural gas networks in the EH (energy hubs). Besides, the existing power grids are getting smarter by implementing the new generation of information technologies and communication systems. In smart grid, the electricity suppliers can modify the customers' electrical load consumption by employing appropriate scheduling schemes such as DR (demand response) programs. In this paper, we consider the S. E. Hubs (smart energy hubs) framework, in which the customers can use EMS (energy management system) to access to the electricity and natural gas prices... 

In this research, effects of superhydrophobic nano-coating on frictional drag force have been investigated. The result of this study could be considered to be used as a method in applications concerned with fuel consumption reduction, less CO2 emission and environmental problems as well as speed increase; while, its significance can also be of great use in marine applications. A rotating disc apparatus was used as the experimental set-up to compare the frictional drag force on an aluminum disc with TiO2 superhydrophobic nano-coating and a smooth coatless aluminum disc. The superhydrophobic nano-coating was prepared using sol-gel method and was shown to be able to produce a contact angle of... 

A thermodynamic model considering flame propagation is presented to predict SI engine characteristics for hydrogen-methane blends. The partially charge stratification approach which involves micro direct injection of pure fuel or a fuel-air mixture, to create a rich zone near the spark plug, is proposed as a method to improve engine performance. Presented approach was validated with experimental data for the natural gas at lean condition. The model was generalized to predict the performance of engine for a variety of hydrogen contents in hydrogen-methane blends. Hydrogen molar concentrations of 0%, 15%, 30%, and 45% were used in the simulations. Results showed that partially charge...