Among the various applications of photocatalysis, this research focuses on the photocatalytic degradation of Ethylenediaminetetraacetic acid (EDTA) over TiO2. The study investigates the mechanism and optimum conditions of the reaction. The objective is to describe the degradation mechanism of EDTA under irradiation, and thereby, determine the best conditions for the reaction to take place efficiently. The mechanism is studied in situ by running DRIFTS-MS investigation, while the reaction takes place inside a reaction cell exposed to radiation from lamps simulating solar or UV-visible broad range radiation to assess the influence of radiation on performance. Other factors, such as the type of reactant gas, flow rate and the presence of humidity, are manipulated and studied individually as well.
An Air-cooled condenser is a device for rejecting heat from a fluid directly to ambient air. The obvious advantage of an Air-cooled condensers is that it does not require cooling water, which means that plants requiring large cooling capacities need not be located near a supply of cooling water. Air cooled condensers are integral part of the process industries and power plants, In natural gas processing plants, air-cooled condensers are popularly used in separation units and this phase changing units controls the economics of the process. An air cooled condenser in Natural Gas Liquid (NGL) plant is modelled using Aspen EDR software, an optimized model is developed by investigating different geometrical parameters of the air cooled condenser. The developed model is validated using the industrial operation data available before performing the simulations. To effectively improve the performance of air-cooled heat exchangers, enhancement techniques are often employed, The Inside and the outside heat transfer coefficients are enhanced using nanostructured condensers and this results are incorporated with the Aspen EDR model so that the fan power cost and the process economics are evaluated. The fan power is evaluated at different operating conditions (summer /winter) and at different air humidities and air velocities. The results showed favorable outcomes based on the simulation and optimization, the operating cost of the practical process can be reduced by a great extent (up to 30%).
Recently, global warming has attracted widely attention. With the upsurge of replacing the third generation refrigerants with low global warming potential (GWP) alternatives, the fourth generation refrigerants mainly promote unsaturated HFCs such as hydrofluoroolefins (HFOs). However, up to date, there are only few compounds available for this new generation, making the search for new ones and blends fulfilling the required conditions in terms of efficiency, safety and environmental is a high priority from the research point of view. Understanding the liquid-vapor interface behavior and predicting reliable thermodynamic properties are important for determining suitable refrigerants for next generation, as thermodynamics rules most of their efficiency. Extensive experimental data should be obtained, and for a wide range of conditions, before a new molecule can be put into the final application. In addition to experimental methods, molecular simulations and theories, such as the statistical associating fluid theory (SAFT), can also provide appropriate ways to describe the phase transition behavior, including interfacial and transport properties. The advantage of using molecular simulations versus theory is that, although more time consuming, they provide additional information at the molecular level, such as orientation of the molecules, accumulation at the interface, etc., not achievable by theory, but essential to understand the behavior of the system. However, to our knowledge, the calculation of the HFOs interfacial properties and mixtures by molecular simulation has not been published yet. In this project, we aim to use MD simulations to study the vapor-liquid interface of different HFOs and their binary mixtures with HFC and alkanes as alternatives to third generation refrigerants. We will also provide predictions on their interfacial properties (such as the corresponding density profiles, thickness of interface and surface tension) from the statistical associating fluid theory (SAFT). Results will be compared to the experimental data and Reference Fluid Thermodynamic and Transport Properties Database (REFPROP). Simulations will allow assessing the quality of the established HFO models in the literature and the performance of SAFT.
Climate change and energy are two of the major challenges facing modern society, with the development of greener and more efficient energy conversion and storage technologies critical for the mitigation of greenhouse gas emissions and meeting the global energy demand in the future. The Lithium ion rechargeable battery provided a breakthrough in modern energy storage; however they are reaching their maximum predicted energy capacity. As a result, scientists are keen to explore rechargeable batteries with higher specific (gravimetric) energy. Among the leading candidates is the lithium-air battery since it is predicted to have the highest theoretical specific energy density among all rechargeable battery devices (3500 Wh kg-1). However, there are some issues which need to be resolved before the launch of a commercial lithium-air battery. Electrode passivation is the leading cause for early cell death due to the diminishing electrode/electrolyte interface. A genuine solution explored in this thesis is the design of hierarchically porous materials like 3DOM porous carbon and hierarchical graphene as "air" electrodes. Hierarchically structured porous materials are nature inspired structures in which the porosity is engineered such that the resulting material composes various porosity scales. The utilization of hierarchical porous materials as cathodes for the Li-air battery could offer several advantages which we aim to verify. Namely, the porosity offers a higher interfacial contact between the electrode and the electrolyte resulting in higher capacity. Moreover, the presence of wider voids in the form of mesopores and macropores offers transport "highways" for faster charge and molecular transport. Most importantly however, the macropores offer the possibility of discharge product (Li2O2) storage without clogging the micropores and mesopores ensuring continuous oxygen transport to the reaction centers and reducing passivation. In a field where the fundamental understanding of electrochemical mechanisms is of great significance, we aim to conduct first principles molecular simulations to model the phenomena occurring at the electrode/electrolyte interface of a Li-air battery. In addition, classical molecular simulations will be utilized to model and characterize the hierarchical porous materials such as 3DOM carbon and hierarchical graphene as cathodes for Li-air batteries. Molecular simulations should provide insights into the possible reaction mechanism occurring on hierarchical cathodes. The main purpose of the thesis is to explore the feasibility of the hierarchical cathodes in improving the efficiency of the Li-air battery, through the proposed improved diffusion and discharge product storage.
In this work, CO2 was absorbed from nitrogen in Polyvinylidene fluoride (PVDF) hollow fiber membrane contactors by using a variety of single and blends of aqueous amine solutions and nanofluids. An ultrasonic dispersion method was used to prepare nanofluids where SiO2 nanoparticles and carbon nanotubes (CNTs) were dispersed in deionized (DI) water without adding any surfactant. The prepared solvents were fed into the tube side of the membrane module, whereas the gas mixture of nitrogen and carbon dioxide (N2/CO2) was passed through the shell side. CO2 absorption experimental runs were carried out at four different liquid flow rates: 10, 20, 30 & 40 ml/min. CO2 concentration was fixed at 20 vol.% in the CO2/N2 gas mixture. The whole experiments were conducted at ambient temperature and atmospheric pressure and absorption by pure deionized water in the same module was used as a reference. The effects of different parameters on the removal efficiency of CO2 were checked and analyzed with a focus on concentrations and types of amines and nanoparticles and liquid flow rate.
The paper focusses on treatment of water containing heavy metals like Hg (II), Pb (II) and Cd (II). An alginate based graphene oxide hydrogel is used as the adsorbent for the same. The kinetics, isotherm and thermodynamic studies are done and discussed.
Recently, multi-rotors are being considered for the transportation of payloads by delivery companies such as Amazon. Transporting a payload to the desired location using a multi-rotor without considering the mission completion feasibility could result in a failure during the transportation mission and cause the multi-rotor to enter fail-safe mode. The outcome of entering into a fail-safe mode could be landing of multi-rotor-payload into an unsafe location, hence a chance of theft or tampering. The following paper presents a method of assessing the chances of a successful mission by using a model of multi-rotor. The model inputs are the multi-rotor parameters, the desired trajectory and the output of the model is the decision whether to start the mission or abort it.
A Graph SLAM algorithm along with an object detection module based on deep learning are employed in order to generate an estimated map of a previously unexplored area. A ZED camera, which provides RGB and depth images, is mounted on a ground vehicle which is moved in the area to be explored in order to collect the required data for mapping. While maneuvering in the environment, the wheel encoders embedded in the ground vehicle are used to estimate the robot's position using dead reckoning.
Robotic Urban Search and Rescue (USAR) is a challenging yet promising research area which has potential applications as proven throughout the rescue and recovery operations in real-world disasters. The main challenge for rescuers is to adapt to the unique conditions of the indoor USAR environment including the inflexible navigation and the harsh conditions. In this paper, we study the different approaches used for exploration in an indoor unstructured environment and propose an efficient exploration method to enhance the existing state of the art exploration strategies. The proposed method considers in the exploration algorithm the extracted contextual information gathered from images. The comparison between the state of the art exploration method is provided.
This paper experimentally illustrates the modeling and simulation of the Lynxmotion Robot, using the robotics toolbox under MATLAB. This project is part of a graduate course on robotics. The main objective of this paper is to control the robot to perform a pick and place task. The task is simulated under MATLAB, where the robot picks objects from known positions and stacks them in target positions. The command is then sent to the robot to execute this task. Furthermore, the robot, with the aid of a vision system, is programmed to work as an autonomous robotic arm that picks up colored objects, and then places them in different positions, based on their colors.
