46 research outputs found

    Corn-Based Deicers - TR754

    Get PDF
    Scaling up the production of agro-byproduct-based deicer is challenging as their yield is far less than the demand. Since corn is the most planted crop in the United States, the current study focuses on developing corn-based deicers that possess lower freezing point depression, enhanced ice melting capacity, and corrosion inhibition properties. The PI hypothesizes that the sugar alcohols/polyols like Sorbitol, Maltitol and Mannitol produced from the corn starch can enhance salt-brine deicer. Various blends of deicers referred to as corn-based deicers are generated by combining corn juice, corn-derived polyols, and salt-brine in different weight fractions and their deicing properties are determined experimentally by performing five tests, namely, freezing point depression, corrosion inhibition, ice melting capacity, skid resistance, viscosity and, dissolved oxygen. Based on the results obtained, a blend of deicer prepared from 27 wt. % Sorbitol+23.3 wt. % salt-brine is recommended to achieve freezing point depressions as low as -38.1°C and, 27 wt. % Maltitol+23.3 wt. % salt-brine is recommended for freezing point depressions between -25°C to -35.6°C. In corrosion-prone zones such as bridge decks, concrete pavements and steel bridges a blend of deicer prepared by adding 0.5-2 wt. % Mannitol to 23.3 wt. % salt-brine is recommended. A blend of deicer prepared from 27 wt. % Mannitol+23.3 wt. % salt-brine is recommended at sub-freezing temperatures of -10°C and -20°C for improved ice melting capacity

    HINDERED DIFFUSION OF COAL LIQUIDS

    Full text link

    Development of New Methodologies for Prediction of Performances of Asphalt Mixtures

    Get PDF
    This thesis proposes the use of new methodologies for prediction of performances of asphalt mixtures. Recent improvements in technology make it possible to adopt new methods of investigation with the dual objective of improving the performance in the survey of the parameters and investigate new properties so far not analyzed. In particular, the image analysis and the tyre/surface interaction belong to an innovative framework, which is next to flank, if not replace, the classic measurements so far employed. The thesis deals with the use of these technologies for the analysis of three rubberized stone mastic asphalts, which were laid on a stretch of road close to Bologna, Italy. Three different surveys were carried out on site during the first year of service. The surveys included the change in texture and skid resistance due to the traffic, along with the acoustic properties of the pavement. Local as well as dynamic continuous measurements were carried out, involving the use of a profilometer and a skiddometer. A second phase involved the prediction of the surface parameters with different stages of simulated trafficking on Road Test Machine. At each stage change in macrotexture, skid resistance, adhesion between bitumen and aggregates, contact pressures and areas were assessed. The image analysis is used for the assessment of the adhesion between the bitumen and the aggregate. The images are then processed in order to create 3D models of the asphalt specimens and investigate the surface and volume properties. The tyre/pavement interaction is another fundamental phenomena that received little considerations from the research, given its importance. A final discussion summarizes these investigations by separately review three different simulated periods, i.e. the early life, the in-service equilibrium and the end of life. In order to accelerate the distress, one slab was subjected to Immersion Wheel Track test

    The Importance of Chain Connectivity in the Formation of Non-covalent Interactions between Polymers and Single-walled Carbon Nanotubes and its Impact on Dispersion

    Get PDF
    Polymer nanocomposites have garnered incredible promise in the field of material science due to the excellent mechanical strength, thermal and electrical conductivities of the nanoparticles and the extension of these properties to the processing flexibility inherent to plastics. However, practical realization of these nanoparticle-based materials has been hindered by the tendency of these nanoparticles to aggregate as a result of strong inter-particle forces. In this dissertation, we investigate the formation of non-covalent charge transfer interactions between polymers and single-walled carbon nanotubes (SWNTs) with the goal of optimizing interfacial adhesion and homogeneity of nanocomposites without modifying the SWNT native surface. Nanocomposites of SWNTs and three sets of polymer matrices with varying composition of electron donating or electron accepting functional groups were prepared. In the first part of this dissertation, quantitative characterization by optical microscopy and Raman spectroscopy and qualitative results through thick film composite visualization show that the existence of a moderate amount of interacting moieties along the polymer chain results in an enhanced intermolecular interaction with SWNT, which translates to an optimum nanoparticle homogeneity. Calculations from density functional theory and Flory-Huggins theory correlate with the experimental results, which illustrate that chain connectivity is critical in controlling the accessibility of the functional groups to form intermolecular interactions. Thus, controlling the amount of interacting functional groups throughout the polymer chain such that an adequate distance between them is realized will direct the extent of charge transfer interaction, which enables tuning the SWNT dispersion. The second part of this dissertation focuses on the elucidation of the morphology of these nanoparticle entities in a polymer matrix. The observance of microphase-separated peaks in the scattering patterns of polyacrylonitrile (PAN) nanocomposites indicate an ordering of the PAN polymer induced by the carbon nanotube cage, which could either be due to a thermodynamically bound layer around the SWNT or the occurrence of SWNT-induced PAN crystallization. Finally, UV-Vis measurements were performed on SWNT-polymer suspension in order to comprehend the interactions that occur during nanocomposite fabrication. These results demonstrate that SWNT dispersions in pure N,N-dimethyl formamide (DMF) are stabilized by the adsorption of polymers onto the SWNTs

    Improving boron for combustion applications

    Get PDF
    Boron has received much attention as a potential additive to explosives and propellants due to its high theoretical gravimetric and volumetric heating values. The challenge, however, is that boron particles tend to agglomerate, have lengthy ignition delays and very low combustion rates. Prior research indicates that boron’s long ignition delays are due to its inhibiting naturally occurring oxide layer, impeding the diffusion of reactants for oxidation. For combustion, current studies report that boron particles have two consecutive stages, but the actual reaction mechanism is poorly understood. Despite many years of relevant research, quantitative combustion data on micron-sized boron particles are limited and most of the proposed modifications of boron powder for its improved ignition and combustion substantially diminish the energy density of the produced composites. Such modifications affect low-temperature oxidation kinetics, and thus, aim to reduce the ignition delay rather than accelerate high-temperature reactions affecting combustion rates and efficiencies. The objectives of this research are to achieve higher burn rates for boron powders without jeopardizing their thermochemical performance, safety and stability, and to develop an experimentally validated model adequately describing boron oxidation kinetics that can be used in practical simulations for a broad range of temperatures. The study is also aimed to close the gap in data for combustion of fine boron particles in varying oxidizing environments. In this work, burn times as a function of particle size, ignition delays and temperatures of commercial and modified boron powders are collected from optical emissions and images of single particles burning in air, steam, and gases formed by combusting hydrocarbons. In each case, the oxidizing gas environment is described accounting for thermodynamic equilibrium and using computational fluid dynamics. Unlike previous work, the complex morphology of boron aggregates is explicitly accounted for by correcting for their fractal dimension. The fractal dimension is determined by scanning electron microscopy (SEM) image analysis by box counting and diffusion limiting cluster morphology theories. Strategies to modify boron’s heterogeneous reactions by functionalizing its surface by organic solvents and using transition metals as “shuttle catalysts” are explored. It is found that washing boron with acetonitrile removes hydrated surface oxide and reduces ignition delays while preventing rapid aging and re-oxidation at ambient conditions. Doping boron with less than 5wt% transition metals (Fe or Hf) by high energy ball milling or wet synthesis, accelerates surface reaction rates leading to shorter particle burn times compared to the starting commercial powder. A kinetic model is derived from low-temperature thermo-analytical measurements to describe the oxidation of complex aggregated boron particles accounting for their surface morphology. Comparison with particle combustion experiments shows that the same model can describe reactions at high temperatures typical of the full-fledged boron combustion, suggesting that the same heterogeneous reactions govern both ignition and combustion of boron. It is found that the morphology of as received boron powders comprising micron-sized agglomerates of finer primary particles does not always change to spherical droplets even at temperatures exceeding the boron melting point. This leads to variation in burn rates and temperatures for various particles

    A Review of Resonant Converter Control Techniques and The Performances

    Get PDF
    paper first discusses each control technique and then gives experimental results and/or performance to highlights their merits. The resonant converter used as a case study is not specified to just single topology instead it used few topologies such as series-parallel resonant converter (SPRC), LCC resonant converter and parallel resonant converter (PRC). On the other hand, the control techniques presented in this paper are self-sustained phase shift modulation (SSPSM) control, self-oscillating power factor control, magnetic control and the H-∞ robust control technique

    OBSERVER-BASED-CONTROLLER FOR INVERTED PENDULUM MODEL

    Get PDF
    This paper presents a state space control technique for inverted pendulum system. The system is a common classical control problem that has been widely used to test multiple control algorithms because of its nonlinear and unstable behavior. Full state feedback based on pole placement and optimal control is applied to the inverted pendulum system to achieve desired design specification which are 4 seconds settling time and 5% overshoot. The simulation and optimization of the full state feedback controller based on pole placement and optimal control techniques as well as the performance comparison between these techniques is described comprehensively. The comparison is made to choose the most suitable technique for the system that have the best trade-off between settling time and overshoot. Besides that, the observer design is analyzed to see the effect of pole location and noise present in the system

    A Review of Resonant Converter Control Techniques and The Performances

    Get PDF
    paper first discusses each control technique and then gives experimental results and/or performance to highlights their merits. The resonant converter used as a case study is not specified to just single topology instead it used few topologies such as series-parallel resonant converter (SPRC), LCC resonant converter and parallel resonant converter (PRC). On the other hand, the control techniques presented in this paper are self-sustained phase shift modulation (SSPSM) control, self-oscillating power factor control, magnetic control and the H-∞ robust control technique

    State-Feedback Controller Based on Pole Placement Technique for Inverted Pendulum System

    Get PDF
    This paper presents a state space control technique for inverted pendulum system using simulation and real experiment via MATLAB/SIMULINK software. The inverted pendulum is difficult system to control in the field of control engineering. It is also one of the most important classical control system problems because of its nonlinear characteristics and unstable system. It has three main problems that always appear in control application which are nonlinear system, unstable and non-minimumbehavior phase system. This project will apply state feedback controller based on pole placement technique which is capable in stabilizing the practical based inverted pendulum at vertical position. Desired design specifications which are 4 seconds settling time and 5 % overshoot is needed to apply in full state feedback controller based on pole placement technique. First of all, the mathematical model of an inverted pendulum system is derived to obtain the state space representation of the system. Then, the design phase of the State-Feedback Controller can be conducted after linearization technique is performed to the nonlinear equation with the aid of mathematical aided software such as Mathcad. After that, the design is simulated using MATLAB/Simulink software. The controller design of the inverted pendulum system is verified using simulation and experiment test. Finally the controller design is compared with PID controller for benchmarking purpose

    Exploring pavement texture and surface skid resistance using soft computing techniques

    Get PDF
    Pavement skid resistance and texture characteristics are important aspects of road safety. Traditional pavement friction measurement from limited contact with pavement is influenced by multiple factors such as temperature, water depth, and testing speed. Friction prediction from texture data has a potential to save resources and reduce inconsistence of friction measurement due to the existence of water and rubber in friction data collection. This dissertation investigates the application of pavement 2-dimensional /3-dimensional (2D/3D) texture data for friction evaluation from different perspectives.3D texture data with ultra-high resolution 3D laser scanner and friction data with Dynamic Friction Tester are collected on the Long Term Pavement Performance (LTPP) Specific Pavement Study 10 (SPS-10) site in Oklahoma. 2D macro-texture data with High Speed Profiler and friction data with Grip Tester are measured on 49 High Friction Surface Treatment (HFST) sites scattered in 12 states in the United States.Firstly, novel 3D parameters, rather than traditional texture indicators, are calculated for 3D texture data to identify the most important and appropriate texture parameters for skid resistance evaluation. Pavement friction models including the identified 3D texture parameters are developed with fairly good accuracy.Secondly, the wavelet and deep learning methodologies are employed to better use 2D macro-texture data. Discrete wavelet transform is implemented to decompose 2D macro-texture data, which are collected on six HFST sites in Oklahoma, into multiple wavelengths. The Total Energy and Relative Energy are calculated as indicators to represent macro-texture characteristics at various wavelengths. A robust non-contact friction prediction model incorporating energy indicators is proposed with good accuracy. In addition, FrictionNet, a Convolutional Neural Network based model, is developed to pairwise relationship between pavement texture and friction using 2D macro-texture profile as a whole. 49 HFST sites distributed in the 12 states are surveyed including various types of lead-in and lead-out pavement sections. The FrictionNet achieves high accuracy for training, validation, and testing in friction prediction.In summary, novel 3D texture parameters for 3D texture data are identified, and new computing technologies are implemented to better use 2D macro-texture data with respect to pavement friction evaluation. The results demonstrate the potential of using non-contact texture measurements for pavement friction evaluation
    corecore