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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

A Simplified Pavement Condition Assessment and its Integration to a Pavement Management System

January 2018 (has links)
abstract: Road networks are valuable assets that deteriorate over time and need to be preserved to an acceptable service level. Pavement management systems and pavement condition assessment have been implemented widely to routinely evaluate the condition of the road network, and to make recommendations for maintenance and rehabilitation in due time and manner. The problem with current practices is that pavement evaluation requires qualified raters to carry out manual pavement condition surveys, which can be labor intensive and time consuming. Advances in computing capabilities, image processing and sensing technologies has permitted the development of vehicles equipped with such technologies to assess pavement condition. The problem with this is that the equipment is costly, and not all agencies can afford to purchase it. Recent researchers have developed smartphone applications to address this data collection problem, but only works in a restricted set up, or calibration is recommended. This dissertation developed a simple method to continually and accurately quantify pavement condition of an entire road network by using technologies already embedded in new cars, smart phones, and by randomly collecting data from a population of road users. The method includes the development of a Ride Quality Index (RQI), and a methodology for analyzing the data from multi-factor uncertainty. It also derived a methodology to use the collected data through smartphone sensing into a pavement management system. The proposed methodology was validated with field studies, and the use of Monte Carlo method to estimate RQI from different longitudinal profiles. The study suggested RQI thresholds for different road settings, and a minimum samples required for the analysis. The implementation of this approach could help agencies to continually monitor the road network condition at a minimal cost, thus saving millions of dollars compared to traditional condition surveys. This approach also has the potential to reliably assess pavement ride quality for very large networks in matter of days. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2018
32

Knowledge, Time Constraints, and Pragmatic Encroachment

January 2013 (has links)
abstract: ABSTRACT In this work, I provide two novel pieces of evidence in favor of the view that there is pragmatic encroachment on knowledge. First, I present an empirical case via the results of a series of recent experiments to show that folk-knowledge attributions may be sensitive to time constraints even when the latter are construed in a non-truth relevant manner. Along the way, I consider some comments made by Jonathan Schaffer (2006) as it pertains to interpreting time constraints-sensitivity in a manner that supports contextualism, before offering reasons to resist such a treatment. I proceed by applying interest relative invariantism to adjudicate a conflict in the epistemology of testimony namely, the positive reasons requirement a la, reductionism vs. non-reductionism. In particular, I highlight how whether an epistemic subject H needs positive non-testimonial reasons to be justified in accepting S's testimony that p, depends on what is at stake for H in believing that p and how much time H has in deliberating about p. / Dissertation/Thesis / M.A. Philosophy 2013
33

Identification and Characterization of Damaging Road Events

Altmann, Craig Tyler 12 June 2020 (has links)
In the field of vehicle durability, many individuals are focusing on methods for better replicating the durability a user will experience throughout the typical design lifespan of a vehicle (e.g., 100,000 miles). To estimate user durability a means of understand the types of damaging events and driving styles of uses must be understood. The difficulty with accurately estimating customer usage is, firstly, there is a large pool of possible roads for a user to drive along, for example, there are over 4 million miles of public roads in the United States, alone [1]. In addition, while measurements of these surfaces could be collected it would be impractical for two reasons, the first is the financial and extreme time burden this would take. Second, when collecting measurements of a road surface only the current state of a road surface can be measured, thus as a road deteriorates or is repaved the measurements collected would no longer be an accurate representation of the road. It should be mentioned that even, if all of the road surfaces were measured performing simulation and analysis of all of these road surfaces would be computationally intensive. Instead, it would be beneficial if select events that account for a significant portion of the damage a vehicle experiences can be identified. These damaging events could then be used in more complex vehicle simulation models and as input and validation of proving ground and laboratory durability testing. The objective of this research is to provide a means for improved estimation of vehicle durability, specifically a means for identifying, characterizing, and grouping unique separable damaging events from a road profile measurement. In order to achieve this objective a measure that can be used to identify separate damaging events from a road profile is developed. This measure is defined as Localized Pseudo Damage (LPD), which identifies the amount of damage each individual road excitation makes to the total accumulated damage for a single load path in a vehicle system. LPD is defined as a damage density to minimize the effect of measurement spacing on the resulting metric. The developed LPD measure is causal in that the value of LPD at a location is not affected by any future locations. In addition, for a singular event (e.g., impulse or step) in the absences of other excitations, the LPD value at the singular event location is equivalent to the total pseudo damage divided by the step size at the location. Once a measure of pseudo damage density is known at multiple locations along a road profile for multiple load paths of interest, then separable damaging events can be identified. To identify separable damaging events the activity of the vehicle system must be considered because separate damaging events can only occur when a region of inactivity is present across all load paths. Subsequently, an optimization problem is formed to determine the optimal active regions to maintain. The cost function associated with the optimization problem is defined to minimize the cost (number of locations maintained in damaging events) and maximize the benefit (the amount of pseudo damage maintained). Lastly, a statistical test is developed to assess if separate damaging events can be considered to be from the same general class of events based on their damage characteristics. The developed assessment methods establish the similarity between two more separable damaging events based on application specific user defined inputs. In the development, two example similarity metrics are defined. The first similarity metric is in terms of distance and the second is in terms of likelihood (probability). The developed statistical analysis uses the current state-of-the-art in clustering algorithms to allow for multiple damaging events to be identified and grouped together. / Doctor of Philosophy / In the automotive field determining the level of damage a typical production vehicle experiences over its lifetime has always been a desirable criterion to identify. This criterion is commonly referred to as customer usage. By understanding the typical customer usage of a vehicle over the lifetime of a vehicle, automotive engineers are able to improve the design of vehicle components. The issue with defining customer usage is that there are millions of miles of roads that a customer can travel on and millions of customers that all have unique driving characteristics. While it is possible to collect measurements of these road surfaces to use in further vehicle simulations, it is not feasible both from a financial and time perspective. In addition, the simulation and analysis of all road surfaces would be computationally intensive. However, if select damaging events (regions of the road surface that excessively contribute to accumulated damage) are identified, then they can be used in more complex vehicle durability analyses with lower computational efforts. In conventional damage analysis a total amount of accumulated damage is established for a known road surface. The issue with defining damage this way is that unique events which likely contributed a large amount of the accumulated damage cannot be identified. The first objective of this research is to define damage as a function of the vehicle's location along a road surface. Then, unique and separable damaging events can be identified and separated from sections of the road that do not significantly contribute to the accumulated damage. After defining this measure, an optimization problem is developed to identify damaging events based on maximizing the benefit (amount of damage accounted for in damaging events) and minimizing the cost (amount of road surface retained). Unique and separable damaging events are identified by solving this optimization problem. While the optimization problem identifies unique, separable damaging events, it is likely that some damaging events contain similar characteristics to each other. When performing additional durability analysis, it would be beneficial to form connections between similar damaging events to allow for analysis to be performed based on groups of events. To identify damaging events with similar characteristics, a statistical analysis is developed as the last contribution of this work. By combining this analysis with current state-of-the-art clustering algorithms and user provided definitions based on applications, similar damaging events are able to be grouped together.
34

The colonial approaches by the Iranian regime towards the Kurds during the Jîna Uprising : A case study of the Jîna Uprising through an internal colonial lens

Bahzad, Lavin January 2024 (has links)
In September 2022, the state murder of Jîna Amini, a 22-year-old Kurdish woman, by the Islamic Republic's morality police in Tehran sparked a nationwide uprising, the largest since the 1979 revolution. With a central point of the movement in Kurdistan, this study aims to determine whether the Islamic Republic of Iran's (IRI) methods constitute a continuation of colonial practice. The study employs case studies and content analysis using the "internal colonialism" paradigm from the limitations of a time frame of 2022 to 2023. Findings highlight a colonial relationship between IRI and Kurdistan, which plays a heavy role in the case of Jîna Amini and the Jîna Uprising. The attempts to subjugate Amini's Kurdishness and Kurdistan discloses the institutionalized racial hierarchy within IRI. The disproportionate use of force, as observed in cases of heavy militarization, securitization, arrests, brutal treatment of protesters and prisoners, sexual violence, and the killing of Kolberis, all point to colonial structures. Essentially, this study provides a critical reassessment of the human rights violations perpetrated by IRI through colonial methods.
35

A Discrete Roughness Index for Longitudinal Road Profiles

Zamora Alvarez, Eric Jose 12 January 2016 (has links)
Engineers of off-road equipment, on-road vehicles, pavement, and tires must assess the roughness of a terrain surface for the design of their products. The International Roughness Index (IRI), a standardized means of assessing longitudinal road roughness, quantifies roughness based on the average suspension travel for a particular vehicle at a prescribed speed. The Discrete Roughness Index (DRI) developed in this work address fundamental limitations of the IRI. Specifically, the DRI is calculated for each discretely measured location along a terrain surface and is applicable to vehicles traveling at varying speeds and using parameters other than the Golden Quarter-Car on which the IRI is based. The development of the DRI begins with a consistent discretization of the terrain surface, vehicle response, and the IRI. Next the Fractional Response Coefficient is developed, the properties of which are critical in the development of the DRI. The DRI is developed and its properties are discussed through theory and simulation of the ASTM E1926-08 profile. One important property of the average DRI is that it converges to the IRI as the distance between sampled points becomes smaller, for the particular case when the Golden Quarter-Car model is simulated at 80 kph. The DRI is not an alternative to the standard IRI, therefore, but a widely applicable roughness measure of which the standard IRI is a single specialized application. / Master of Science
36

Designens hållbarhetskraft : En kvalitativ studie om design och hållbarhet inom produktutveckling av dagligvaror / Design your way to sustainability : A qualitative study about design and sustainability within the product development of Fast Moving Consumer Goods

Carlsson, Priscilla, Nikkhooye Panahi, Sandra January 2019 (has links)
Hållbarhet värderas allt högre utav konsumenter och allt fler företag satsar på ett utökat hållbarhetsarbete. Detta innebär att företag borde utveckla sitt hållbarhetsarbete för att bli eller fortsätta att vara konkurrenskraftiga. Konsumtionen av livsmedel står för 25 % av hushållens klimatpåverkan. Inom dagligvaruindustrin finns därmed en stor potential för förbättring. För ett utvecklat hållbarhetsarbete krävs innovativa lösningar. Design som process har visat sig kunnabidra med detta. Dock har studier visat på att trots att företag värderar design högt så implementeras det inte i samma utsträckning. Potentialen som design innehar riskerar därmed att gå förlorad av aktörerna på marknaden. Uppsatsen ämnar till att undersöka vilka faktorer som är viktiga för att design skall implementeras för att utveckla hållbara produkter inom dagligvaruindustrin. Studien är en multipel fallstudie med en kvalitativ ansats. Tre intervjuer har genomförts med europeiska företag som verkar på den svenska dagligvaru- och livsmedelsmarknaden. Studien visade på vikten av att företag genomsyras av hållbarhet och har en hög förståelse fördesign. Det är av vikt att såväl design som hållbarhet implementeras i början av produktutvecklingsprocessen som även kallas för Front-End. / Sustainability is increasingly valued by consumers and more companies are expanding the incorporation of sustainability in their work. This means companies should develop the incorporation of sustainability in their work to stay or become competitive on the market. The consuming of groceries accounts for 25 % of the households climate influence. Within the fast moving consumer goods industry there is therefore a potential of improvement. To develop the incorporation of sustainability in a company requires innovative solutions. Design as a process has been able to contribute with exactly this. Although, studies have shown that even though companies value design highly it is not implemented to the same extent. The potential that design possesses is therefore at risk of being lost by the actors of the market. The thesis intends to explore which factors that are important for design to be implemented to develop sustainable products in the fast moving consumer goods industry. The study is a multiple case study with a qualitative approach. Three interviews have beenmade with european companies that are active on the swedish fast moving consumer goodsindustry market. The study showed that it is of importance for a company to be permeated by sustainability andto have a high understanding of design. Furthermore, it is of importance that design as well assustainability is implemented in the beginning of the product development process that is also known as Front-End.
37

Road surface profile monitoring based on vehicle response and artificial neural network simulation

Ngwangwa, Harry Magadhlela January 2015 (has links)
Road damage identification is still largely based on visual inspection methods and profilometer data. Visual inspection methods heavily rely on expert knowledge which is often very subjective. They also result in traffic flow interference due to the need for redirection of traffic to alternative routes during inspection. In addition to this, accurate high-speed profilometers, such as scanning vehicles, are extremely expensive often requiring strong economic justifications for their acquisition. The low-cost profilometers are very slow, typically operating at or less than walking speeds, causing their use to be labour-intensive if applied to large networks.This study aims at developing a road damage identification methodology for both paved and unpaved roads based on modelling the road-vehicle interaction system with an artificial neural network. The artificial neural network is created and trained with vehicle acceleration data as inputs and road profiles as targets. Then the trained neural network is consequently used for reconstruction of road profiles upon simulating it with vertical vehicle accelerations. The simulation process is very fast and can often be completed in a very short time thus making it possible to implement the methodology in real-time. Three case studies were used to demonstrate the feasibility of the methodology and the results on field tests carried out on mine vehicles with crudely measured road profiles showed a majority of the tested roads were reconstructed to within a fitting accuracy of less than 40% at a correlation level of greater than 55% which in this study was found to be practically acceptable considering the limitations imposed by the sizes of the haul trucks and their tyres as well as the quality of the road profiles and lack of control in the vehicle operation. / Thesis (PhD)--University of Pretoria, 2015. / Mechanical and Aeronautical Engineering / Unrestricted
38

Model-Based Road Roughness Estimation

Agebjär, Martin January 2024 (has links)
Road roughness is the primary source of vehicle vibrations. This thesis investigates model-based methods for estimating road roughness in terms of the International Roughness Index (IRI) by measuring the chassis vibrations of the vehicle. This can provide NIRA Dynamics AB with a cost-effective pavement monitoring solution. Initially, system identification is performed on a physical car to estimate model parameters that reflect reality. Subsequently, two model-based IRI estimation methods are developed. One method relies on a transfer function between vertical chassis vibrations and the IRI according to a quarter-car model. The second method aims first to estimate the longitudinal road profile using a Kalman filter, and then calculate the IRI values from the estimated profile. This method can be implemented computationally efficiently and also offers the possibility of estimating the IRI using lateral vibrations. Both methods are validated using real-world data, and their performance is similar when using vertical vibrations, with the IRI estimation error’s standard deviation being roughly 10% to 20% of the reference value. However, the results are considerably worse when the estimation is purely based on lateral vibrations, indicating that lateral vibrations are not feasible for model-based IRI estimation, and the reasons for this are discussed.
39

Propuesta de gestión para mantener la rugosidad dentro de los niveles de servicio del contrato de concesión

Lluncor Gallo, Robert Alexander, Salcedo Barrios, Richard Gerardo January 2015 (has links)
La presente investigación lleva como título “Propuesta de Gestión para mantener la Rugosidad dentro de los Niveles de Servicio del contrato de concesión”. La investigación se enfoca en dar una alternativa de gestión que asegure mantener los niveles de servicio en lo referente a la calidad del pavimento cuando la carretera se encuentra en estado de conservación reduciendo el costo que se va a invertir en años futuros teniendo como base datos obtenidos desde el año 2010 al 2015. El deterioro prematuro del pavimento se ve afectado cuando no se tiene un plan de conservación adecuado que conlleve a programar y ejecutar actividades de mantenimiento rutinario y periódico con la finalidad de mantener los niveles de servicio en carreteras concesionadas. Esto conlleva que la condiciones de las redes viales se encuentren por debajo de lo que resulta deseable y conveniente, presentando un ciclo vicioso de la vía (Construcción – Abandono – Destrucción – Reconstrucción). La investigación es de tipo cuantitativo no experimental, descriptivo, correlacional y explicativo. Su diseño es longitudinal ya que tiene como referencia datos obtenidos desde el año 2010 al 2015. Se analizaron dos propuestas de gestión de conservación vial teniendo como base los datos procesados de los años 2010 al 2015 para obtener una alternativa que logre cumplir con el objetivo principal de ésta investigación. Finalmente se concluye que es posible formular una propuesta de gestión vial que permita optimizar el presupuesto de mantenimiento en los años proyectados conservando la calidad del pavimento. Analizando la posibilidad y conveniencia de postergar el mantenimiento periódico considerando que los valores de rugosidad, estén dentro de los niveles admisibles reemplazándolo por intervenciones de menor costo. This research is entitled "Management Proposal to maintain the roughness within Service Level concession contract." The research focuses on providing an alternative management to ensure maintain service levels in terms of the quality of the pavement when the road condition in reducing the cost to be reversed in future years on the basis of data from 2010 to 2015. Premature pavement deterioration is affected when there is no proper conservation plan that may lead to program and implement activities of routine and periodic maintenance in order to maintain service levels in toll roads. This means that the conditions of the road networks are below what is desirable and convenient, featuring a vicious cycle route (Construction - Abandonment - Destruction - Reconstruction). The research is not experimental, descriptive, correlational and quantitative explanatory. Its design is longitudinal and whose reference data from 2010 to 2015. Two proposals for road maintenance management on the basis of processed data for the years 2010 to 2015 for an alternative that would meet the main objective of this research is analyzed. Finally we conclude that it is possible to formulate a proposal for road management for optimizing the maintenance budget in projected years preserving the quality of the pavement. Analyzing the possibility and desirability of postponing regular maintenance considering that the roughness values, are within acceptable levels by replacing lower-cost interventions.
40

Experimentální identifikace profilu vozovky / Experimental Identification of Road Profile

Baroš, Martin January 2016 (has links)
The diploma thesis focuses especially on a design of a way for evaluating roughness in road profile, which affects driving characteristics of a car and a ride. In the theoretical part of the thesis are mentioned the most used methods and tools for road roughness analysis in the world. For the purposes of this thesis an experimental measuring were undertaken in order to obtain data for the own design of a road profile analysing system.

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