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Articles 631 - 660 of 699

Full-Text Articles in Civil and Environmental Engineering

Construction Cost Of Underground Infrastructure, Seyed Behnam Hashemi Jan 2008

Construction Cost Of Underground Infrastructure, Seyed Behnam Hashemi

Civil Engineering Theses - Archive

Renewal of aging underground infrastructure is a major challenge that municipalities inNorth America face every day. Traditional replacement or renewal of these underground utilitiesuses open-cut excavation methods that can be disruptive to everyday life of citizens andexpensive, particularly in built-up areas and in projects with difficult ground and site conditions. Incontrast, trenchless technologies use innovative methods, materials, and equipment that requireminimum surface excavation to renew and construct aging underground infrastructure. Thesenew methods are considered to be more safe, cost-effective, efficient and productive thanconventional open-cut projects. However, to select trenchless technologies in utility design,consulting engineers and utility owners need to compare …


Adsorption Curve Fits For Landfill Vocs On Bituminous Coal Based And Coconut Shell Based Activated Carbon, Annaprabha Athappan Jan 2008

Adsorption Curve Fits For Landfill Vocs On Bituminous Coal Based And Coconut Shell Based Activated Carbon, Annaprabha Athappan

Civil Engineering Theses - Archive

This study explores adsorption as a method of controlling hazardous gas emissions from Municipal Solid Waste Landfills (MSWL). In particular, the hazardous air pollutants (HAPs) para, meta, and ortho-xylene, ethylbenzene and methyl ethyl ketone are selected for experimental study. Activated carbon is a good adsorbent and well known for its high surface area. Among the many varieties of activated carbon, bituminous coal based activated carbon (BPL) and coconut shell based activated carbon (OVC) are compared in this study. Each experiment was conducted in a vial with a known amount of carbon in it. The pollutant concentration remaining in the vial …


Assessing Control Strategies For Ground Level Ozone, Neelesh Vijay Sule Jan 2008

Assessing Control Strategies For Ground Level Ozone, Neelesh Vijay Sule

Civil Engineering Dissertations - Archive

Developing cost effective control strategies for ozone has been a challenge to air quality modelers. Conventionally, the control strategies are applied across-the board to the region. The main aim of this research was to develop a Decision-Making Framework (DMF) for evaluating and optimizing the selection of ozone control strategies. Conventional across-the-board reductions conduct emission reductions uniformly throughout the region and throughout the day. By contrast, this dissertation studied targeted reductions, in which emission sources of various types are reduced at various times and locations. The proposed DMF comprised of four phases: (1) Initialization, (2) Mining, (3) Metamodeling, and (4) Optimization. …


Measured And Theoretical Response Of Perpetual Pavement Structures, Miguel M. Portillo Jan 2008

Measured And Theoretical Response Of Perpetual Pavement Structures, Miguel M. Portillo

Civil Engineering Theses - Archive

The Kansas Perpetual Pavement experiment includes the construction of four pavement sections on the US-75 highway designed according to the perpetual pavement concept. The sections were instrumented with strain gauges and pressures cells to measure strains and stress at the bottom of the base layer and at the top of the subbase layer. Pavement response measurements were carried out in seven occasions between July 2005 and October 2007 with a loaded truck. Measured values obtained show that longitudinal and transverse values were almost always below the average endurance limit of 70 microstrains. The measurements also showed that temperature and vehicle …


Statistical Approach To The Development Of A Microscale Model For Estimating Exhaust Emissions Of Light Duty Gasoline Vehicles, Benjamin Nmai Afotey Jan 2008

Statistical Approach To The Development Of A Microscale Model For Estimating Exhaust Emissions Of Light Duty Gasoline Vehicles, Benjamin Nmai Afotey

Civil Engineering Dissertations - Archive

Today, air pollution is taking a growing toll on human health, the environment and the economy, despite decades of efforts to combat it. Although it was once a primary urban phenomenon in industrialized countries, today air pollution has spread worldwide. Mobile, industrial and natural sources constitute the major sources of air pollution. Around the world, major cities in industrialized countries have in recent times been battling air pollution from mobile sources. Beijing, New Delhi, Dallas/ Fort Worth and Los Angeles are no exceptions.Pronounced interest has focused on mobile source (vehicle exhaust) emissions in recent decades. A rapid increase in the …


Multi-Criteria Assessment For Supporting Freeway Operations And Management Systems, Auttawit Upayokin Jan 2008

Multi-Criteria Assessment For Supporting Freeway Operations And Management Systems, Auttawit Upayokin

Civil Engineering Dissertations - Archive

Freeway traffic congestion represents an increasing concern for urban areas throughout the United States. In addition, faced with limited roadway expansion alternatives, transportation agencies are considering investment in traffic management centers (TMCs) as a more viable way to operate and manage freeways effectively. The TMCs' responsibilities include monitoring roadway conditions using the various data collection strategies and determining performance measures for freeway operations. At the same time, traffic engineers at the TMCs may react to the traffic congestion problems by implementing operational strategies. In order to provide reliable decision support for TMC freeway operations and management systems, this dissertation aims …


Capacity Of Two-Sided Type C On Freeway With Four Lanes, Shadi Ghasemi-Majd Jan 2008

Capacity Of Two-Sided Type C On Freeway With Four Lanes, Shadi Ghasemi-Majd

Civil Engineering Theses - Archive

Weaving segments are categorized based on weaving length, configuration, number of lanes, free flow speed and weaving ratio. All these parameters affect weaving capacity. One of the objectives of this research was to extend Phong Thanh Vo's dissertation and study the relation between weaving capacity of two-sided type C on freeways with four lanes and any potential variables (mainalane demand, entrance ramp demand, exit ramp demand and weaving ratio). Micro-simulation has been used in order to analyze different capacity scenarios and the VISSIM calibrated model by Vo was used. Also, the effect of each of the VISSIM calibration parameters on …


The Effect Of Displacement Control Loading Histories On Genral Connecting Surfaces Using Finite Element Analysis, Sanjog Chandrakant Sabnis Jan 2008

The Effect Of Displacement Control Loading Histories On Genral Connecting Surfaces Using Finite Element Analysis, Sanjog Chandrakant Sabnis

Civil Engineering Theses - Archive

Displacement loading history provided by the AISC Seismic Provision 2002 is commonly used for experimental testing and analytical modeling of beam-to-column steel connection to stimulate the seismic effect. However, the basis for the above loading history is not documented in the literature. Thus, this study developed 25 cyclic load cases by varying the frequency and magnitude of the AISC-2002 loading within a predefined envelops. The 25 load cases are obtained from five different load sets in which the concept of uniform and non-uniform frequencies and amplitude are utilized. All the load cases are limited to the displacement equivalent to the …


Clay Mineral Quantification Using Gravemetric Analysis, Sarwenaj Ashraf Jan 2008

Clay Mineral Quantification Using Gravemetric Analysis, Sarwenaj Ashraf

Civil Engineering Theses - Archive

The current procedure used by the Texas Department of Transportation (TxDOT) to determine the type of stabilizer is based mainly on the Plasticity Index (PI) and the gradation of the soil. This method of stabilization does not always work because two soils with the same PIs can have very different shrink/swell potential, plastic limits or liquid limits, hence their behavior may be very different. This is mainly due to the fact that two soils that have the same PI can have very different clay mineral composition. Montmorillonite and kaolinite are the clay minerals that cause swelling/shrinking in soils.Chittoori (2008) had …


Studies On Field Stabilization Methods To Prevent Surficial Slope Failures Of Earth Fill Dams, Venkata S. Dronamraju Jan 2008

Studies On Field Stabilization Methods To Prevent Surficial Slope Failures Of Earth Fill Dams, Venkata S. Dronamraju

Civil Engineering Dissertations - Archive

Surficial failures are occurring frequently on the slopes of earthfill dams which are predominantly rainfall induced. Desiccation cracks form on the slope surface during dry environment which accelerates infiltration during rainfall. Infiltration causes increase of pore water pressures and saturation of soil mass in top layer resulting in surficial failures. Numerous surficial failures occurred on the slope of earthfill dams maintained by The United States Army Corps. of Engineers. The current research is undertaken at the University of Texas at Arlington with an objective of exploring the best field stabilization method to mitigate these surficial failures.Two sites, Joe Pool Dam …


Novel Stabilization Methods For Sulfate And Non-Sulfate Soils, Chakkrit Sirivitmaitrie Jan 2008

Novel Stabilization Methods For Sulfate And Non-Sulfate Soils, Chakkrit Sirivitmaitrie

Civil Engineering Dissertations - Archive

Expansive soils are commonly found in arid and semi-arid climate zone. These soils typically exhibit moderate to high plasticity, low to moderate strength, and high swell and shrinkage characteristic which in turn result in more swelling problems when the soil absorbs water. Both low strength characteristic and volumetric movements weaken the subgrade soils that they may lead to structural distress on road pavements. This research project was conducted at the City of Arlington, Texas. Soils in Arlington are known to be highly expansive. The expansive soils consist of both sulfate-rich soils and non-sulfate soils. This research project was conducted to …


Trends Of Vehicular Emissions For Clean Air Associates Precombustion Retrofit Device, Jaya Vani Nagireddi Dec 2007

Trends Of Vehicular Emissions For Clean Air Associates Precombustion Retrofit Device, Jaya Vani Nagireddi

Civil Engineering Theses - Archive

The research study objective was to find if there was any reduction in onboard exhaust emissions from a light duty passenger car (2007 Dodge Charger) with a Clean Air Catalytic Converter manufactured by Clean Air Associates, Inc. The research was conducted by the Civil and Environmental Engineering Department, University of Texas at Arlington as part of the North Central Texas Council of Governments Aftermarket Technology and Fuel Additive Research Program. Initially, emissions of pollutants were measured without the Clean Air Associates' retrofit device, called Baseline testing. A Horiba OBS-1300 On-Board System measured concentrations of the pollutants NOx, CO, CO2 and …


Modeling Unsaturated Soil Response Under Suction-Controlled Multi-Axial Stress States, Arthit Laikram Dec 2007

Modeling Unsaturated Soil Response Under Suction-Controlled Multi-Axial Stress States, Arthit Laikram

Civil Engineering Dissertations - Archive

In this research work, a novel suction-controlled true triaxial testing apparatus has been developed to test 3-in (7.5-cm) side, cubical specimens of unsaturated soil under controlled-suction states for a wide range of stress paths that are not easily achievable in a conventional cylindrical apparatus. The equipment is a mixed-boundary type of device, with the specimen seated on top of a high-air-entry ceramic disk and between five flexible (latex) membranes on the remaining sides of the cube. The new cell is an upgraded, more elaborate version of the one previously reported by Hoyos (1998), featuring two independent pore-air and pore-water pressure …


Ductile Lightweight Concrete For Lightweight Structural Application, Ake Piyamaikongdech Dec 2007

Ductile Lightweight Concrete For Lightweight Structural Application, Ake Piyamaikongdech

Civil Engineering Theses - Archive

This study developed a ductile concrete for precast wall systems which are capable of resisting high wind in excess of 500 mph. The developed concrete mix design consists of sand, cement, glass fiber, and a foaming agent to produce lightweight concrete in the range of 87 pcf (1392 kg/m3) to 90 pcf (1440 kg/m3). A comprehensive testing program for evaluation of the developed concrete material was undertaken. The mix designs were prepared both in the laboratory and in the mix truck with drum capacity of 27 ft3 (0.77 m3), and 177.6 ft3 (5 m3), respectively. The large concrete batches using …


The Effect Of Temperature On Fiber Composite Bridge Decks, Mahesh Gajula Nagabhushanam Dec 2007

The Effect Of Temperature On Fiber Composite Bridge Decks, Mahesh Gajula Nagabhushanam

Civil Engineering Theses - Archive

The use of Fiber composite honeycomb structure's as bridge decks gained importance, because of its low light weight and ease of installation. In this study, The Fiber composite bridge decks were subjected to thermal gradients. The Fiber composite bridge decks were fabricated in sizes of 2 feet x 8 feet x .5 feet and 4 feet x 8 feet x .5 feet specimens by Kansas structural composites Inc. The program consisted of 3 specimens of size 2 feet x 8 feet x .5 feet with ribs oriented along longitudinal direction, 3 specimens of size 2 feet x 8 feet x …


Deep Mixing Technology For Mitigation Of Swell-Shrink Behavior Of Expansive Soils Of Moderate To Deep Active Depths, Raja Sekhar Madhyannapu Dec 2007

Deep Mixing Technology For Mitigation Of Swell-Shrink Behavior Of Expansive Soils Of Moderate To Deep Active Depths, Raja Sekhar Madhyannapu

Civil Engineering Dissertations - Archive

Expansive soils are well known for their cyclic shrink-swell behavior due to seasonal related moisture changes. These cyclic movements of expansive soils are due to physico-chemical changes at particle level that are dependent on mineralogical composition of these soils. The subsoil depths susceptible to moisture changes are known as active zones and based on previous studies vary from shallow to deep depths. Movements from these active depths reflect to the surface and cause considerable damages to overlying infrastructures. These damages are slow and time dependent as the in situ moisture fluctuations are slow and continue with time. Since the current …


Comparison Of Distributed Versus Lumped Hydrologic Simulation Models Using Stationary And Moving Storm Events Applied To Small Synthetic Rectangular Basins And An Actual Watershed Basin, Michael Jay Shultz Nov 2007

Comparison Of Distributed Versus Lumped Hydrologic Simulation Models Using Stationary And Moving Storm Events Applied To Small Synthetic Rectangular Basins And An Actual Watershed Basin, Michael Jay Shultz

Civil Engineering Dissertations - Archive

The purpose of this investigation is to compare simulations using several artificial rectangular basins and a real drainage basin for distributed and lumped hydrologic models via results obtained with the U.S. Geological Survey Modular Modeling System (MMS). Impervious watershed conditions were assumed for each simulation. A critical objective of this investigation is to assess the performance of a physically-simple lumped model compared to a more physically-complex distributed model for various storm events. Knowledge gained from this investigation may be applied to the practical problem of determining when either a distributed or lumped model may be expected to function well given …


Regression Model For Prioritization Of Corridors When Retiming Traffic Signals, Manjari G. Mittal Nov 2007

Regression Model For Prioritization Of Corridors When Retiming Traffic Signals, Manjari G. Mittal

Civil Engineering Theses - Archive

Traffic signals are used by transportation engineers to safely and efficiently manage vehicle, bicycle and pedestrian traffic on roadways. However, to maintain the effectiveness of traffic signals, traffic signals should be adjusted or retimed periodically to match the current traffic patterns. Traffic signal retiming is one of the most cost effective ways available to transportation engineers for reducing delays and mitigating congestion. A region may contain a large number of traffic signals all of which cannot be retimed at once due to limited availability of funds and other resources; only a subset of signals can be retimed at any given …


Vehicular Emissions Models Using Mobile6.2 And Field Data, Abhishek Yerramalla Aug 2007

Vehicular Emissions Models Using Mobile6.2 And Field Data, Abhishek Yerramalla

Civil Engineering Theses - Archive

Regression models to predict vehicular emissions for different categories of vehicles for different pollutants are presented in this thesis. Vehicular emissions are affected by numerous variables which, among others, include speed, temperature, acceleration, deceleration, driving behavior and meteorological data. Regression models are developed based on data obtained from Mobile 6.2 and on-board emissions measurements. The U.S. Department of Transportation (US DOT) conducted sensitivity analysis of Mobile6 where they evaluated different parameters used to find the emission factors, such as vehicle miles traveled, speed, humidity, etc. The sensitivity analysis investigated the overall Mobile6.2 model behavior for various conditions. In the analysis, …


Experimental And Field Monitoring Studies On Recycled Materials As Pavement Bases, Sunil Kumar Sirigiripet Aug 2007

Experimental And Field Monitoring Studies On Recycled Materials As Pavement Bases, Sunil Kumar Sirigiripet

Civil Engineering Theses - Archive

Natural aggregates derived from a variety of source rocks have been used as a road base material. But the extraction of natural aggregates resources is increasingly being constrained by urbanization, increased costs and environmental concerns. Thus, increased amounts of reclaimed materials are being used to supplement natural aggregates in road construction. Recycled Asphalt Pavement (RAP) material is one of the important recycled materials used in the present geotechnical applications. Many agencies are constantly seeking to reap the benefits of utilizing RAP. Main advantages of utilizing RAP include the preservation of the existing profile, conservation of asphalt and aggregate resources, conservation …


The Travel Behavior Of Minority Cohorts In Texas, Gustavo A. Jimenez Vera Aug 2007

The Travel Behavior Of Minority Cohorts In Texas, Gustavo A. Jimenez Vera

Civil Engineering Theses - Archive

Texas is changing dramatically; the most conservative population forecast indicates that Hispanics will account for 50% of the Texas population before 2035. Not only is the number of Hispanics on the rise in Texas, but also the foreign-born share has increased dramatically over the last 15 years. The State of Texas is now a majority minority state, and minority cohorts are expected to grow and become more than 65% of the Texas population before 2035. Transportation professionals in the State of Texas are wondering how these demographic changes will affect the transportation system. To gain an understanding of this, one …


Roadway Shallow Water Flow Modeling By Velocity Distribution, Chirakarn Sirivitmaitrie Aug 2007

Roadway Shallow Water Flow Modeling By Velocity Distribution, Chirakarn Sirivitmaitrie

Civil Engineering Dissertations - Archive

Manning's equation is a widely used method for determining flow discharge in a channel with unconfined gravity flow. The roughness value, n-value, is a critical factor for Manning equation to obtain the accurate amount of flow. A precise estimation of Manning "n" is difficult to obtain and varies by investigator justification and experience. Flow on a roadway is a type of open channel flow normally determined by Manning's equation. To ensure reliability and highway safety, the hydraulic geometry dimensions such as spread, depth and discharge must be accurately estimated. A Texas Department of Transportation Manning n-value research project collected data …


Capacity Estimation Of Two-Sided Type C Weaves On Freeway, Phong Thanh Vo Jul 2007

Capacity Estimation Of Two-Sided Type C Weaves On Freeway, Phong Thanh Vo

Civil Engineering Dissertations - Archive

A weaving section is a common design on major highway facilities that has been an interest to researchers for years. Weaving areas are characterized by frequent lane changes, which significantly reduce the capacity of the freeway system. The 2000 Highway Capacity Manual (HCM) defined weaving capacity as "any combination of flows that causes the density to reach the LOS E/F boundary condition of 43 pcpmpl for freeways" based on configuration, number of lanes in the weaving section, free-flow speed, length of the weave, and volume ratio (VR). However, no research has been focused on the two-sided type C weaves, which …


Dynamic Chracteristics And Stability Analysis Of Muncipal Solid Waste In Bioreactor Landfills, Mohamed Adil Haque Jul 2007

Dynamic Chracteristics And Stability Analysis Of Muncipal Solid Waste In Bioreactor Landfills, Mohamed Adil Haque

Civil Engineering Dissertations - Archive

Bioreactor landfills are operated to enhance refuse decomposition, gas production, and waste stabilization. The major aspect of bioreactor landfill operation is the recirculation of generated leachate back through the refuse mass. Due to the accelerated decomposition and settlement of solid waste, bioreactor landfills are gaining popularity as an alternative to the conventional landfill designed under Subtitle D regulations. However, recirculation of leachate or addition of water to accelerate the waste decomposition changes the biodegradation and geotechnical characteristics of waste mass. Our understanding of changes in engineering characteristics of solid waste with accelerated decomposition is limited. There is a need to …


Experimental Studies To Address Strengths Of Limestone Cores, Sulfate Heave Problems In Limestone Cores And Tunnel Lining, Vivekananda Chikyala May 2007

Experimental Studies To Address Strengths Of Limestone Cores, Sulfate Heave Problems In Limestone Cores And Tunnel Lining, Vivekananda Chikyala

Civil Engineering Theses - Archive

Sulfate induced heave is a common scenario in tunnels located on sedimentary rocks containing Pyrites. Pyrite oxidation produces Gypsum which is a major source of natural sulfates. DART NC -1B tunnel is located in Dallas, north Texas. Dallas is located on sedimentary rocks with high Pyrite content and has a history of sulfate induced heave problems in several projects. In spring 2005 & 2006, the shotcrete liner in DART NC-1B tunnel showed cracking associated with water leaks. Considering the local geology and the history of the tunnel, researchers at The University of Texas at Arlington (UTA) suspected probable occurrence of …


Performance Studies On Rigid Pavement Sections Built On Stabilized Sulfate Soils, Deepti Vasudev May 2007

Performance Studies On Rigid Pavement Sections Built On Stabilized Sulfate Soils, Deepti Vasudev

Civil Engineering Theses - Archive

Soils of Southeast Arlington are highly expansive and rich in sulfates. They undergo sulfate induced heaving when traditional calcium based stabilizers are used for soil stabilization (Puppala et al. 1998). Traditional stabilizers do not provide effective solution since they are known to induce heaving, termed in the literature as sulfate induced heaving (Hunter, 1988). Both swelling and softening of these soils rich in sulfates induce considerable damage to overlying pavement infrastructure. Typically, high sulfate soils treated with calcium based stabilizers form ettringite mineral. Ettringite undergoes heaving when hydrated (Hunter, 1988; Puppala et al. 2001). Since this sulfate-induced heave is caused …


Effects Of A Debonding Flaw Size And Location On The Flexural Performance Of Cfrp Retrofitted Steel Sections, Sharad C. Choudhary May 2007

Effects Of A Debonding Flaw Size And Location On The Flexural Performance Of Cfrp Retrofitted Steel Sections, Sharad C. Choudhary

Civil Engineering Theses - Archive

In US there are several thousand steel bridges at present. Out of them many bridges are at various level of advance deteriorations due to many years of service life and environmental factors. These bridges cannot be fully replaced so retrofitting is the best choice .Earlier steel plates were used. With introduction of FRP in 1960.It is replacing the steel plates as they are lighter in weight and can be made stronger than steel. While installation of these FRP some kinds of Flaws are encountered. The variation of strength of carbon fiber reinforced laminate used for structural repair or strengthening containing …


Runway Incursion Mitigation, Capacity Enhancement, And Safety Improvements With Perimeter Taxiway Operations At Dallas Fort Worth International Airport, Satyamangalam D. Satyamurti May 2007

Runway Incursion Mitigation, Capacity Enhancement, And Safety Improvements With Perimeter Taxiway Operations At Dallas Fort Worth International Airport, Satyamangalam D. Satyamurti

Civil Engineering Dissertations - Archive

A perimeter taxiway (PT) or end-around taxiway (EAT) operation is a new concept being developed at several airports around the country to eliminate active departure runway incursions during peak periods. PTs will enhance capacity by permitting uninterrupted, safe, continuous takeoffs and landings within the operations framework and guidelines established by the Federal Aviation Administration (FAA). For this research, the Dallas/Fort Worth International Airport's (DFW) proposed PT operations are considered for analysis and evaluation. This concept is tested using actual historical flight data at DFW for simulation and analytical modeling based on the FAA safety factors available in the Visual SIMMOD …


Permeability Of Municipal Solid Waste In Bioreactor Landfill With Degradation, Kiran Kumar Penmethsa May 2007

Permeability Of Municipal Solid Waste In Bioreactor Landfill With Degradation, Kiran Kumar Penmethsa

Civil Engineering Theses - Archive

Bioreactor landfills are operated and controlled to accelerate refuse decomposition, gas production and biological stabilization of the municipal solid waste (MSW). Leachate recirculation in bioreactor landfill creates a favorable environment for rapid microbial decomposition of the biodegradable components of solid waste. Therefore, clear understanding of the mechanism of moisture movement within the solid waste would be necessary for successful design and operation of the bioreactor landfill. Permeability is an important parameter during the design of leachate collection and recirculation system. In the current study an experimental program was designed to determine the variation of coefficient of permeability of MSW with …


Autotrophic Denitrification Of Groundwater In A Granular Sulfur-Packed Up-Flow Reactor, Shih-Hui Pan May 2007

Autotrophic Denitrification Of Groundwater In A Granular Sulfur-Packed Up-Flow Reactor, Shih-Hui Pan

Civil Engineering Dissertations - Archive

Autotrophic denitrification is an effective treatment technique for nitrate removal from groundwater. Six basic elements are required for the growth of autotrophic denitrifiers: (1) electron donor, (2) electron acceptor, (3) active bacteria, (4) anoxic/anaerobic environment, (5) micronutrients, and (6) optimum pH and temperature. In this research, granular sulfur is an electron donor; nitrate is an electron acceptor; anoxic and anaerobic environment was maintained in the reactor, and micronutrients were added; pH was controlled between 6 and 9, and temperature was maintained at the room temperature (20 + 2 oC). Batch reactor and continuous up-flow reactor experiments were carried out to …