In this work we reproduce driving techniques to mimic expert race drivers and obtain the open-loop control signals that may be used by auto-pilot agents driving autonomous ground wheeled vehicles. Race drivers operate their vehicles at the limits of the acceleration envelope. An accurate characterization of the acceleration capacity of the vehicle is required. Understanding and reproduction of such complex maneuvers also require a physics-based mathematical description of the vehicle dynamics. While most of the modeling issues of ground-vehicles/automobiles are already well established in the literature, lack of understanding of the physics associated with friction generation results in ad-hoc approaches to tire friction modeling. In this work we revisit this aspect of the overall vehicle modeling and develop a tire friction model that provides physical interpretation of the tire forces. The new model is free of those singularities at low vehicle speed and wheel angular rate that are inherent in the widely used empirical static models. In addition, the dynamic nature of the tire model proposed herein allows the study of dynamic effects such as transients and hysteresis. The trajectory-planning problem for an autonomous ground wheeled vehicle is formulated in an optimal control framework aiming to minimize the time of travel and maximize the use of the available acceleration capacity. The first approach to solve the optimal control problem is using numerical techniques. Numerical optimization allows incorporation of a vehicle model of high fidelity and generates realistic solutions. Such an optimization scheme provides an ideal platform to study the limit operation of the vehicle, which would not be possible via straightforward simulation. In this work we emphasize the importance of online applicability of the proposed methodologies. This underlines the need for optimal solutions that require little computational cost and are able to incorporate real, unpredictable environments. A semi-analytic methodology is developed to generate the optimal velocity profile for minimum time travel along a prescribed path. The semi-analytic nature ensures minimal computational cost while a receding horizon implementation allows application of the methodology in uncertain environments. Extensions to increase fidelity of the vehicle model are finally provided.

The goal of this thesis is to develop an active front steering(AFS) control system which can apply to ordinary vehicle. This AFS control system stabilizes the driving vehicle and reduces the possibility of rollover. This thesis uses magic formula tire model and constructs a vehicle model with eight degrees of freedom to study the dynamic behavior of the real driving vehicle. This thesis constructs a vehicle model with three degrees of freedom and eight degree of freedom, compare with two vehicle model, we adopt eight vehicle model in this thesis. The advantages of PI controller are low cost and easy to modify, so this thesis adopts PI controller as the control strategy. This study uses four simulate methods and compares the simulated results to develop the AFS control system which can apply to ordinary vehicle.

Statistic data indicates that about 100,000 tones of waste tire were generated each year. Current recycling market of waste tire is very small. Therefore, many waste tires remain untreated and cause severe health and safety problems in storage. PP fiber cut end is the waste material after cutting off the fiber. Traditional reuse way was to be the toy¡¦s fillers. If we can reuse the materials properly to develop a market of additional value, it will be a big contribution to the society. In this research, recycled waste tire powder and PP fiber cut end are used as oil adsorbents for the purpose of oil recovery during the process of oil spill emergency response. PP fiber cut end and waste tire powder are capable of adsorbing oil due to their hydrophobic surface property and the capillary forces developed during the contact with oil, therefore, makes them a perfect material for oil recovery. The major advantage of recycled PP fiber cut end is its high oil adsorbing capacity (approximately 48.4g/g). But, after reuse, its oil adsorbing speed was slow down, so does the oil adsorbing capacity. On the other hand, with good elasticity, the waste tire powder can be reused for more than 100 times without loosing its capability. However, the oil adsorbing capacity of waste tire powder is far less than PP fiber (approximately 2.84g/g). Finally, we combine PP fiber cut end and waste tire powder, to see if we can take the advantage of each product and make the best utilization of the composite material. Results indicate the composite material can be reused for more than 100 times without loosing its capability, and its performance is even better than the combination of each individual product. In the other test, we can see the composite material can not only adsorb engine oil and crude oil, but also adsorb emulsified oil. In the test, the composite material can recover up to 28 times of its own weight of oil. With the invented set up, the oil recover work is much easier to operate, and moreover, the composite material is less expensive. Only a squeeze roller and a collection container are required to recover oil. So, the composite material is indeed having practicability and mobility. Finally, the composite material is an excellent adsorbent compares with other products available on the market.

This study investigated the production of powdered activated carbon derived from carbon black of pyrolyzed waste tires, and their adsorptive capacity on vapor-phase mercury chloride (HgCl2) using both adsorption column and thermogravimetric adsorption systems. The adsorption isotherms and kinetic models were further simulated in the study. In addition, an innovative compositive impregnation process was developed to increase the sulfur content of powdered activated carbon derived from waste tires. The activation of carbon black to form powdered activated carbon was performed in a tubular oven. The operating parameters including activation temperatures, activation time, and water feed rates were investigated in this study. Experimental results indicated that the yield of carbon-black derived powdered activated carbon (CBPAC) decreased with the increase of activation temperature, activation time, and water feed rate, while the BET surface area and pore volume decreased. In the comparison of activation time and water feed rate in the activation process, activation time had an important impact on the production of specific surface area than water feed rate. The optimal operating parameters included activation temperature of 900¢J, activation time of 180min, water feed rate of 0.5 mLH2O/gC-sec, and water injection behind activation process of 17.5 min. From the analysis of carbon surface, the carbon contents of powdered carbon black (PCB), CBPAC, commercial powdered activated carbon (CPAC) were 89.5%, 87.6%, and 88%, respectively. The C (1s) peak region of PCB consisted of 49.8% C-C, 38.9% C-O, 10.5% C=O or O-C-O. Similar analysis results showed that the total area of the C (1s) peak region of CBPAC consisted of 57.5% C-C, 26.8% C-O, 8.1% C=O or O-C-O, and 7.6% O-C=O. Similar to CPAC, the C (1s) peak region consisted of 42.6% C-C, 41.8% C-O, and 15.6% O-C=O. Furthermore, the sulfur contents of PCB and CBPAC were both 0.5%. The S (2p) peak region of PCB consisted of 58.9% ZnS (zinc sulfide) and 41.1% S=C=S. For CBPAC, the S (2p) peak region solely contained S=C=S. The comparison of two sulfur impregnation processes revealed that the innovative compositive impregnation process could simultaneously increased the sulfur content and the BET surface area of powdered activated carbon (PAC), however, the direct impregnation process increased the sulfur content while the BET surface area of PAC decreased linearly. Without the disadvantages of time and energy consumption associated with direct impregnation, the compositive impregnation is an efficient and energy-saving process for producing sulfurized PAC with a high BET surface area and high sulfur content. Experimental results obtained from the adsorption column tests indicated that the influence of the adsorption depth on the adsorptive capacity of CBPAC did not vary much, while the adsorptive capacity of CBPAC increased with HgCl2 concentration. Furthermore, the adsorptive capacity of CBPAC on vapor-phase HgCl2 was less than that of CPAC at the adsorption temperatures of 25~150¢J and high humidity of 12.3 wt %. The difference of adsorptive capacity for CBPAC and CPAC correlated closely with BET surface area and sulfur content. Results form the thermogravimetric adsorption analysis indicated that the adsorptive capacity of CBPAC and initial adsorption rate on vapor-phase HgCl2 increased with HgCl2 concentration and decreased with adsorption temperature. In the kinetic modeling, the deviation of experimental and simulated values simulated by the pseudo-first-order model was lower than those of pseudo-second-order models. Furthermore, the r (correlation coefficient) of pseudo-first-order and pseudo-second-order models were 0.9745~0.9977 and 0.9217~0.9780, respectively. It suggested that the pseudo-first-order model could simulate the adsorption of HgCl2 onto CBPAC better than pseudo-second-order model.

ABSTRACT In this paper we describe the use of electrospray-assisted pyrolysis ionization/mass spectrometry (ESA-Py/MS) to selectively ionize trace polar compounds that coexist with large amounts of nonpolar hydrocarbons in synthetic polymer, crude oil, amber, humic substances, and rubber. Samples of different origins are distinguished rapidly by their ESA-Py mass spectra without prior separation or chemical pretreatment. During ESA-Py analysis, the samples in their solid or liquid states were pyrolyzed at 590 ¢XC using a commercial Curie-point pyrolytical probe; the gaseous pyrolysates were transferred into a glass reaction cell; the polar compounds (M) in the pyrolysates were then ionized in the form of protonated molecules (MH+), through their reactions with the charged species in the ESI plum. Although the major components of the pyrolysates are nonpolar hydrocarbons, their lack of functional groups that can receive a proton in the ESA-Py source results in no hydrocarbon ion signals being produced; thus, the ions detected in ESA-Py mass spectra all result from trace polar component in the pyrolysates.

Retroreflective Raised Pavement Markers (RRPMs) supplement other pavement markings to provide guidance to road users. Previous research concerning durability of the RRPMs suggests that their performance has been degrading over the years. One of the main causes for underperformance of the RRPMs is the lack of appropriate laboratory testing standards that can test the adequacy of the RRPMs to perform in field conditions. There is a need to modify the existing standards or develop new testing procedures that can better simulate field conditions. This requires identifying critical locations and magnitudes of stresses inside the markers during the tire-marker impacts that happen on roads. The goal of this research was to identify critical magnitudes and locations of the stresses in RRPMs during the tire-marker impacts by doing the finite element modeling and simulation of the impacts, and use the information to recommend laboratory testing procedures that could simulate real-world conditions. The researcher modeled and simulated the tire-marker impacts using the finite element tools Hypermesh and LS DYNA. He calibrated the material properties of the marker models to improve the tiremarker model. Based on the tire-marker impact simulations, the researcher concluded that the critical compressive stresses during impacts are located at the edge contacts of retroreflective sides with the top surface. The critical stresses may also occur at lower and upper corners of the marker. The other areas, especially the lower half of the marker, had tensile stresses. Angle of impact was found to be a critical external variable that affected the stresses inside the markers and the marker-pavement interface forces. The researcher then modeled and simulated a few laboratory-testing procedures that could simulate the field performance of the RRPMs. Based on these simulations, the researcher recommended that the ASTM compression test for evaluation of RRPMs be continued or a similar test be developed. He suggested development of one new test (named as offset compression test) that could better replicate the field conditions. He also recommended having a review of the ASTM flexural test.

Recently Michelin has been developing a new airless, integrated tire and wheel combination called the Tweel. The Tweel promises performance levels beyond those possible with conventional pneumatic technology because of its shear band design, added suspension, and decreased rolling resistance. However, many questions remain as to what kind of environmental impact this radical new design will have. The environmental impact of the Tweel will be compared to a current radial tire used on BMWs, but because of the complexity in manufacturing, using, and disposing these tires it is somewhat difficult to compare environmental problems. Currently there are environmental issues all throughout a tire's lifespan from rubber manufacturing emissions to tire disposal, and the rapidly growing method to evaluate all of these points is Life Cycle Analysis (LCA). LCA is the essential tool required by businesses in order to understand the total environmental impact of their products - cradle-to-grave. By considering the entire life cycle of a Tweel from manufacturing, through use and disposal, and comparing it to knowledge of current tires, an accurate assessment of the entire environmental impact of the Tweel will be made. Since the Tweel is currently still in the research phase and is not currently manufactured and used however, there are uncertainties with respect to end-of-life scenarios and rolling resistance estimates that will affect the LCA. Thus, it will be important to consider a range of options to determine which one will have the most environmental benefits while still keeping the strengths of the Tweel design intact.

Tires serve as important components of wheeled vehicles and their analytical modeling has drawn the attention of many researches in the past decades. A high-resolution finite element (FE) tire model contains detailed structural and material characteristics of a tire that exhibit degrees-of-freedom (DoF) in the order of 10⁵ or greater. However, such high-resolution models in their full detail are not practically applicable in multibody dynamic analysis of vehicles and a reduction in their order becomes necessary. In this research different formulations to construct condensed FE tire models suitable for multibody simulations are developed and their characteristics are discussed. In addition, two new and novel forms of substructuring are presented that aim at isolating the contact region of a tire without the need for keeping the boundary DoF which otherwise remain in the reduced system in the standard substructuring procedures. The new substructuring methods provide a great tool in constructing condensed FE tire models with much less total number of DoF compared to cases where a standard substructuring is used. In order to increase the computational efficiency of the condensed FE tire models even further, the possibility of model condensation in the contact region is studied. This research also addresses the applicability of available friction models into the condensed FE tire models. Different formulations of a condensed tire model presented in this research are used to construct several computational models. These models are utilized to simulate certain scenarios and the results are discussed.

Mobili žemės ūkio technika neigiamai veikia dirvą dėl varančiųjų ratų didelės apkrovos, buksavimo bei vėžių susiformavimo. Šių procesų pasekmė - dirvos suslėgimas, dirvožemio struktūros ardymas bei sąlygų vandens ir vėjo erozijai susidarymas. Dėl šių priežasčių mažėja derlius ir didėja energijos sąnaudos dirvai įdirbti. Vienas iš būdų optimaliau paskirstyti apkrovą dirvai - keisti slėgį padangose atsižvelgiant į dirvos fizines mechanines savybes. Šiame tiriamajame darbe nagrinėjama oro slėgio padangose įtaka dirvos suslėgimui. Tyrimai atlikti prieš rudeninę sėją, lengvo priesmėlio lauke. Prieš atliekant tyrimus dirva buvo suarta 20 cm gyliu. Dirvos drėgnis 5 cm gylyje buvo 12 %. Tyrimais nustatytas 1,9 MPa mažesnis dirvos slėgis esant 0,5 bar slėgiui padangose lyginant su 2,5 bar slėgiu padangose. Dirvos kietis buvo mažesnis 4,8 karo, 5 cm gylyje, ties armens padu iki 4,1 karto. / Mobile agricultural machinery negatively affects soil due to large load of driving wheels, constant slippage and track formation. Consequently, problems such as soil compaction, damage of soil structure and conditions for water and wind erosion occur. For these reasons, yields decline and energy costs for soil cultivation increase. One of the ways to streamline the distribution of load on soil is to change the pressure in the tires considering on the soil physical and mechanical properties. This research work focuses on the investigation of tire pressure influence on soil compaction. Investigations were carried out before the autumn sowing on a light sandy loam field. Before the tests the soil was plowed 20 cm depth. Soil moisture at a depth of 5 cm was 12 %. The studies revealed that soil compaction of 1,9 MPa was lower at 0,5 bar pressure in the tires compared to the 2,5 bar pressure. Soil compaction was found to be 4,8 times lower in 5cm depth whereas compaction at the tractor track was 4,1 times lower.

Darbo tikslas - atliekant arimo darbus nustatyti traktoriaus buksavimo, degalų sąnaudų bei padangų temperatūros kitimo nuo jo balastavimo ir oro slėgio padangose dydžio priklausomybes. Darbe nagrinėjama balastinės masės ir oro slėgio padangose įtaka traktoriaus eksploataciniams rodikliams. Pateikiami eksperimentiniai tyrimai, kurių metu, keičiant balastinės masės ir oro slėgio padangose reikšmes, buvo matuojamos degalų sąnaudos, varančiųjų ratų buksavimas bei padangų temperatūra. / Work theses - at tillage work investigate tractor wheel skid, fuel consumption and tire temperature dependence from tractor ballast weight and tire pressure. This study investigates a ballast weight and tire pressure influence on tractor’s unit performance. Experimental studies have been performed by changing the weight of ballast and tire pressure values, fuel consumption, wheel skid and tire temperature were measured.