Problems associated with traffic, such as traffic congestionand pollution, have occurred in major urban areas in particulardue to the increased use of cars. One possible way to reducethe use of cars is to replace commuter trips by car with othermodes of transport, such as a combination of car and publictransport called Park&amp;Ride. The aim of this thesis was tounderstand more about factors influencing the choice of modeand to find measures that could attract car drivers to Park&amp;Ride. A stated preference survey has been conducted inorder to quantify some standard factors. The factors used inthis stated choice experiment were: security at the lot,availability of spaces at the parking lot, costs at the parkinglot and walking distances between the parking space and thestation. The results indicate that security at the Park&amp;Ride facility is important. Both sexes assign a high value tosecure parking, but women are more willing to pay for lights atan unguarded parking lot. The results reveal that parkingfacilities, such as free parking and short distance betweenparking place and work at work, influence people’s choiceof mode. A general conclusion is that there is potential forincreasing the use of Park&amp;Ride facilities, especiallyamong women and respondents over 30 years. Key words:Mode choice, valuation, traffic reduction,stated preference, factors, Park&amp;Ride / <p>NR 20140805</p>

Existing studies on the formulation of regulations for online ride-hailing platforms merely see the process as a struggle between interest groups. They do not address how policymakers perceive this struggle and act on their own initiative to govern these platforms. This study supplements existing studies by exploring how the metropolitan governments of two Chinese cities, Beijing and Shanghai, perceived conflicts between contending forms of chauffeur businesses and brought in regulations for new platform ventures. This thesis employs a policy change approach in the Chinese authoritarian context and reaches three conclusions. Firstly, it explains that the "special interests" of taxi entities institutionalized by the old regulatory regimes for taxi businesses incentivized the two metropolitan governments to protect taxi entities. Thus, even if Beijing and Shanghai had different first responses towards platforms with one initially emphasizing "cracking-down" and the other working on a "loose" regulatory approach, they adopted similar platform-capping policies. Secondly, this thesis finds that the two metropolitan governments cautiously disobeyed the central government's "loose" directives for platforms by combining their capping policies with selectively implementing a central directive of differentiating the markets of ride-hailing platforms and taxi operators. Thirdly, this thesis addresses obstructions to the establishment of "new regulation" that respects the business logic of platforms, which is proposed by the platform coalition. It argues that the interaction between the vested "special interests" and the fragmentation of authority makes local governments resistant to this "new regulation." / Graduate

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The increased integration of distributed and renewable energy resources (DERs) has motivated the evolution of new standards in grid interconnection requirements. New standards have the requirement for the DERs to remain connected during the transient grid fault conditions and to offer support to the grid. This requirement is known as the fault ride-through (FRT) capability of the inverter-based DERs and is an increasingly important issue. This dissertation presents the FRT capability of the DERs that employ a voltage control strategy in their control systems. The voltage control strategy is increasingly replacing the current control strategy in the DERs due to the fact that it provides direct voltage support. However, the voltage control technique limits the ability of direct control over the inverter current. This presents a challenge in addressing the FRT capability where the problem is originally formulated in terms of the current control. This dissertation develops a solution for the FRT capability of inverters that use a voltage control strategy. The proposed controller enables the inverter to ride through the grid faults and support the grid by injecting a balanced current with completely controlled real and reactive power components. The proposed controller is flexible and can be used in connection with various voltage control strategies. Stability analysis of the proposed control structure is performed based on a new linear time-invariant model developed in this dissertation. This model significantly facilitates the stability and design of such control loops. Detailed simulation, real-time and experimental results are presented to evaluate the performance of the proposed control strategy in various operating conditions. Desirable transient and steady-state responses of the proposed controller are observed. Furthermore, the newly established German and Danish grid fault ride-through standards are implemented in this research as two application examples and the effectiveness of the dissertation results are illustrated in the context of those two examples.

No description available.

No description available.

No description available.

An essential tool in the truck development process is the ability to quantify and grade vehicle dynamic behavior. Today this is performed either through subjective or objective tests. Subjective tests have the disadvantage that numerous factors influence test drivers’ opinions while objective measures have the advantage of repeatability. However, objective methods of today are often only able to provide a rough grading of vehicles. The main objective with this thesis is to develop more sensitive objective methods for ride comfort evaluation. An effective test procedure to measure driver perception sensitivity to small differences in vehicle ride is suggested and utilized. The driver sensitivity is tested on dynamic behavior that is typically graded in vehicle development. Cab motions from a truck are first measured and then recreated in a simulator where a test driver is seated. The perception threshold for small changes in typical vehicle motion is established in this way for each test person. The perception sensitivity tests indicate that humans are quite sensitive to transients in vehicle motion. One problem with many common vehicle ride measures is that the impact of transient behavior is small due to the averaging used to condense the measurement data into scalar measures. A new evaluation method for ride comfort, with influences from the well known handling diagram, is suggested. This method has four main advantages: it is fairly simple to interpret, it shows the absolute vibration level, it considers transient events separately and it shows changes in vehicle character with increasing excitation. Promising results from both measurements and simulations are derived. New technology has made it possible to vary vehicle suspension parameters during vehicle ride. In order to prescribe different damping for different vehicle modes, modal motion estimates are needed. A system identification approach is suggested. It yields improved estimates of vehicle modal motion compared to previous work. / QC 20101221

Existing literature on the relationship between ridehailing (RH) and transit services is limited to empirical studies that rely on self-reported answers and lack spatial and temporal contexts. To fill this gap, the research takes a novel approach that uses real-time geospatial analyzes. Using this approach, we estimate the extent to which ride-hailing services have contributed to the recent decline in public transit ridership. With source data on ridehailing trips in Chicago, Illinois, we computed the real-time transit-equivalent trip for the 7,949,902 ridehailing trips in June 2019; the sheer size of this sample is incomparable to the samples studied in existing literature. An existing Multinomial Nested Logit Model was used to determine the probability of a ridehailer selecting a transit alternative to serve the specific origin-destination pair, P(Transit|CTA) . The study found that 31% of RH trips are replaceable, 61% are not replaceable, and 8% lie within the buffer zone. We measured the robustness of this probability using a parametric sensitivity analysis, and performed a two-tailed t-test, with a 95% confidence interval. In combination with a Summation of Probabilities, the results indicate that the total travel time for a transit trip has the greatest influence on the probability of using transit, whereas the airport pass price has the least influence. Further, the walk time, number of stops in the origin and destination census tracts, and household income also have significant impacts on the probability of using transit. Lastly, we performed a Time Value Analysis to explore the cost and trip duration difference between RH trips and their transit-equivalent trips on the probability of switching to transit. The findings demonstrated that approximately 90% of RH trips taken had a transit-equivalent trip that was less expensive, but slower. The main contribution of this study is its thorough approach and fine-tuned series of real-time spatial analyzes that investigate the replaceability of RH trips for public transit. The results and discussion intend to provide perspective derived from real trips and encourage public transit agencies to look into possible opportunities to collaborate with ridehailing companies. Moreover, the methodologies introduced can be used by transit agencies to internally evaluate opportunities and redundancies in services. Lastly, we hope that this effort provides proof of the research benefits associated with the recording and release of ridehailing data. / Master of Science / Existing literature on the relationship between ridehailing (RH) and transit services is limited to empirical studies that rely on self-reported answers and lack spatial and temporal contexts. To fill this gap, the research takes a novel approach that uses real-time geospatial analyzes. Using this approach, we estimated the extent to which ride-hailing services have contributed to the recent decline in public transit ridership. With source data on ridehailing trips in Chicago, Illinois, we computed the real-time transit-equivalent trip for the 7,949,902 ridehailing trips in June 2019; the sheer size of this sample is incomparable to the samples studied in existing literature. An existing Multinomial Nested Logit Model was used to determine the probability of a ridehailer selecting a transit alternative to serve the specific origin-destination pair, P(Transit|CTA) . The study found that 31% of RH trips are replaceable, 61% are not replaceable, and 8% lie within the buffer zone. We measured the robustness of this probability using a parametric sensitivity analysis, and performed a two-tailed t-test, with a 95% confidence interval. In combination with a Summation of Probabilities, the results indicate that the total travel time for a transit trip has the greatest influence on the probability of using transit, whereas the airport pass price has the least influence. Further, the walk time, number of stops in the origin and destination census tracts, and household income also have significant impacts on the probability of using transit. Lastly, we performed a Time Value Analysis to explore the cost and trip duration difference between RH trips and their transit-equivalent trips on the probability of switching to transit. The findings demonstrated that approximately 90% of RH trips taken had a transit-equivalent trip that was less expensive, but slower. The main contribution of this study is its thorough approach and fine-tuned series of real-time spatial analyzes that investigate the replaceability of RH trips for public transit. The results and discussion intend to provide perspective derived from real trips and encourage public transit agencies to look into possible opportunities to collaborate with ridehailing companies. Moreover, the methodologies introduced can be used by transit agencies to internally evaluate opportunities and redundancies in services. Lastly, we hope that this effort provides proof of the research benefits associated with the recording and release of ridehailing data.

This study includes an experimental evaluation of a prototype trailing-arm suspension for heavy trucks. The primary goal of this new suspension is to match or improve the kinematics and dynamic performance of an existing "Z-bar" suspension. Significant reductions in cost, weight, and number of parts are the main reasons for this redesign. A permanent facility is constructed to support the testing of different heavy truck suspensions. For actuation of the vehicle suspension, hydraulic actuators are used in the kinematics tests in a quasi-dynamic manner. For the dynamic tests, the vehicle is excited using two hydrodynamic actuators. A collection of forces, displacements, velocities, and accelerations are measured during the tests using transducers that were installed on the suspension and test vehicle. The test measurements are analyzed in both time and frequency domains and then the results of the two suspensions were compared to establish the dynamic merits of the prototype suspension. The kinematics tests include vertical stiffness, roll stiffness, and roll steer measurements for each suspension. The results from the kinematics tests show that the trailing-arm suspension exhibits kinematics traits that are quite similar to the "Z-bar" suspension, within the context of the tests conducted in the study. The dynamic testing consists of three input signals commonly used for such tests, namely: a chirp signal input, a step signal input, and a range of pure tone inputs. The test results show that the resonant frequencies of the two primary suspensions differ by an amount that is most likely too small to affect ride dynamics. The two suspensions, however, exhibit significantly different damping characteristics. The new suspension has much less frictional damping than the existing suspension. This is expected to provide better ride characteristics, assuming that the primary dampers (shock absorbers) are properly tuned for the vehicle that the new suspension was designed for. / Master of Science