Levelized cost of energy (LCOE) analysis of Hexcrete wind towers

Wind power generation has witnessed a dramatic growth in the 21st century. The Department of Energy (DOE) had a vision for wind energy that it would change into an extensively greater part of overall power generation in the U.S. by 2050. As specified by the DOE, wind power generation has grown by trifold from 2008 to 2013. This study presents a constructible, financially feasible alternative wind tower design to the 80 m steel tower platform which has the potential to decrease the overall Levelized cost of energy (LCOE). A hexagonal concrete wind tower solution is evaluated to facilitate the fabrication of a taller wind turbine generator to harvest more powerful, stable, and frequent wind resources for elevating wind energy production to cut down the overall LCOE. Subject matter experts from the industry were benefitted from to develop a process and estimate the cost and schedule of development and assembly of this process. To mitigate uncertainties and quantify risks, a sensitivity analysis was carried out on cost and schedule estimates. Also, estimating LCOE of wind towers is a primary requirement for efficient assimilation of wind power generation in the electricity market. In the state of Iowa, wind power is rapidly becoming a significant electricity generator. Unpredictable outputs and different options for deploying wind towers are one of the major problems of power system operators. Good estimation tools are important and will be needed to integrate wind energy into the economic power plant. The other objective of this research is to propose a GIS-based map to visualize LCOE of different wind tower construction options in various locations. Therefore, wind speed GIS mapping by using weather information will be crucial. Calculation of energy output by applying wind gradient formula to wind speeds energy are performed. The research concludes of Hexcrete towers can be achieved by use of the 120m and 140 m Hexcrete tower platform on certain wind sites in the United States

Otta Seal Construction for Asphalt Pavement Resurfacing

Otta seal resurfacing methods have been widely demonstrated for unpaved roads and road rehabilitation in a few states in the U.S. as well as in Scandinavia and Africa. Application of Otta seal over a deteriorated hot mix asphalt (HMA) surface has been considered as the feasible concept that has not been applied for real construction. In this study, a double-layer Otta seal construction over HMA surface was monitored. The applied materials for the construction were introduced. The following performance of the constructed Otta seal layers was evaluated by measuring the international roughness index (IRI) and dust. The road IRI did not significantly change, and the dustometer test results indicated satisfied dust control on Otta seal layer. The findings from this study provide guidance on designing and implementing Otta seal on asphalt concrete pavement as a resurfacing overlay

Optimal Cultivation Pattern to Increase Revenue and Reduce Water Use: Application of Linear Programming to Arjan Plain in Fars Province

Because the available water resources of the Arjan plain region in Iran do not fully meet the watering requirements for plants in farmlands, the crops suffer from water stress, a situation that causes them to wilt. The aim of this study is to develop a water resources planning model that helps decision-makers determine an appropriate cultivation pattern, optimize the exploitation from surface water resources, and specify the method of allocating water across different farm crops to minimize the detrimental effects of water shortage. Through investigating various models of water resources planning and properties along with the governing conditions for each of these models, the linear programming model was selected as a suitable option due to its simplicity and practical applicability to water resource allocation planning. The model was run for a five-year period by considering gradual variations through the determination of the most appropriate exploitation pattern from the available water resources (surface and groundwater). Results reveal that the negative water balance can be improved gradually as positive, where it will reach +20 million m3 per year in 2040 from the current deficit of 236 million m3 with an 8% increased net profit

Design, Construction, and Preliminary Investigations of Otta Seal in Iowa

Faced with limited financial resources, pavement engineers constantly seek more durable and economical technologies for road preservations and rehabilitations. Consequently, there have been many efforts to study resurfacing strategies, including various types of sealing for local roads. Among different sealing methodologies, Otta seal is a technique that has not yet been sufficiently studied in the U.S.A. For this investigation, the first Otta seal site in the state of Iowa was constructed using a double-layer Otta seal design over 6.4 km of cracked asphalt pavement. Otta seal design and construction details are documented and discussed, and test sections using various aggregates are compared for performance. The key lesson learned was that proper aggregate selection within gradation limits and aggregate spread rates were critical factors for Otta seal performance. Otta seal capability for holding loose aggregate particles and for dust control were examined, and there were indications that excessive proportion of fine aggregate particles could lead to diminished performance associated with fugitive dust emissions and unbound aggregate particles. Although the Otta seal provided a smooth surface satisfying road user and agency requirements, it did not significantly add structural capacity to the existing asphalt pavement. The findings from this study will benefit road officials and other decision makers who need to consider alternatives for resurfacing distressed low-volume asphalt roads. Low-volume roads represent a large proportion of the route mileage of the transportation infrastructure system, and the cost to secondary road departments of maintaining such roads can be quite important. Over time, Otta seal has exhibited reduced maintenance costs by providing a typical service life of 8 to 12 years for a single-layer Otta seal, compared with 4 to 6 years for single-layer chip seal (1–3). Norway-based Otta seal (graded aggregate) technology, originally developed in the 1960s and used in Scandinavian countries, Africa, and other continents, is an economical and practical alternative to traditional bituminous surface treatments (BSTs). It provides flexible, durable, and impervious surfacing that is more tolerant of higher anticipated pavement deflections on low-volume roads that are sometimes constructed with lower-quality materials (4). Compared with traditional BSTs requiring high-quality materials and specialized expertise, Otta seal can often be constructed using more economical local aggregates and readily available equipment (asphalt distributor, aggregate spreader, pneumatic-tired roller, and mechanical broom) typically used for asphalt maintenance (4). Otta seal, formed by a thin bituminous surface treatment (BST) of graded aggregates, ranging from natural gravel to crushed stone, with a relatively low-viscosity binder, relies on a combination of mechanical particle interlock and the binding effect of asphalt binder to provide a resilient, waterproof membrane over the road surface. The state of South Dakota completed its first Otta seal project in Day County in 2008 to provide a low-cost surface using in-house resources and equipment in place of a standard hot-mix asphalt (HMA) pavement surface (5). Various agencies (city, county, and state department of transportation) in Minnesota have also applied Otta seal for traffic volumes ranging from 100 up to 2,000 vehicles average daily traffic (ADT) since early 2000 (6, 7). Most road sections surfaced with Otta seal in Minnesota have performed well except when they encountered unexpected situations such as unanticipated high traffic volumes or flood damage during their service lives (7). Otta seal construction was also found reasonably affordable compared with HMA or Portland cement concrete (PCC) pavement systems for use on low-volume roads; Otta seal has been considered a cost-effective and durable approach to dust control for gravel roads. In particular for developing countries, the available evidence suggests that Otta seal, surface dressings, and Cape seal are the most cost-effective and durable forms of dust control in relation to life-cycle costs (8–10). The Norwegian Public Roads Administration (NPRA) Guideline 93 (4) was compiled using empirical data and experience from many trials and full-scale projects worldwide. However, in the U.S.A., few states have used the Otta seal, and hence, it is felt that a more comprehensive research along with full documentation is necessary to assist in the implementation of Otta seals in Iowa and many other states in the U.S.A

Optimal Cultivation Pattern to Increase Revenue and Reduce Water Use: Application of Linear Programming to Arjan Plain in Fars Province

Because the available water resources of the Arjan plain region in Iran do not fully meet the watering requirements for plants in farmlands, the crops suffer from water stress, a situation that causes them to wilt. The aim of this study is to develop a water resources planning model that helps decision-makers determine an appropriate cultivation pattern, optimize the exploitation from surface water resources, and specify the method of allocating water across different farm crops to minimize the detrimental effects of water shortage. Through investigating various models of water resources planning and properties along with the governing conditions for each of these models, the linear programming model was selected as a suitable option due to its simplicity and practical applicability to water resource allocation planning. The model was run for a five-year period by considering gradual variations through the determination of the most appropriate exploitation pattern from the available water resources (surface and groundwater). Results reveal that the negative water balance can be improved gradually as positive, where it will reach +20 million m3 per year in 2040 from the current deficit of 236 million m3 with an 8% increased net profit

Multi-objective Bayesian Optimization of Super hydrophobic Coatings on Asphalt Concrete Surfaces

Conventional snow removal strategies add direct and indirect expenses to the economy through profit lost due to passenger delays costs, pavement durability issues, contaminating the water runoff, and so on. The use of superhydrophobic (super-water-repellent) coating methods is an alternative to conventional snow and ice removal practices for alleviating snow removal operations issues. As an integrated experimental and analytical study, this work focused on optimizing superhydrophobicity and skid resistance of hydrophobic coatings on asphalt concrete surfaces. A layer-by-layer (LBL) method was utilized for spray depositing polytetrafluoroethylene (PTFE) on an asphalt concrete at different spray times and variable dosages of PTFE. Water contact angle and coefficient of friction at the microtexture level were measured to evaluate superhydrophobicity and skid resistance of the coated asphalt concrete. The optimum dosage and spray time that maximized hydrophobicity and skid resistance of flexible pavement while minimizing cost were estimated using a multi-objective Bayesian optimization (BO) method that replaced the more costly experimental procedure of pavement testing with a cheap-to-evaluate surrogate model constructed based on kriging. In this method, the surrogate model is iteratively updated with new experimental data measured at proper input settings. The result of proposed optimization method showed that the super water repellency and coefficient of friction were not uniformly increased for all the specimens by increasing spray time and dosage. In addition, use of the proposed multi-objective BO method resulted in hydrophobicity and skid resistance being maximally augmented by approximately 23% PTFE dosage at a spray time of 5.5 s

Polyurethane-carbon microfiber composite coating for electrical heating of concrete pavement surfaces

Electrically-heated pavements have attracted attention as alternatives to the traditional ice/snow removal practices. Electrically conductive polymer-carbon composite coatings provide promising properties for this application. Based on the concept of joule heating, the conductive composite can be utilized as a resistor that generates heat by electric current and increases the surface temperature to melt the ice and snow on the pavement surface. This research investigates the feasibility of applying an electrically conductive composite coating made with a Polyurethane (PU) binder and micrometer-scale carbon fiber (CMF) filler as the electrical heating materials on the surface of Portland cement concrete (PCC) pavements. PU-CMF composite coatings were prepared using different volume fractions of CMF, applied on the PCC surfaces, and evaluated in terms of volume conductivity, resistive heating ability, durability, and surface friction properties at the proof-of-concept level. A conceptual cost analysis was performed to compare this method with other heated pavement systems with respect to economic viability. Percolative behavior of CMF in PU matrix was captured and most desirable CMF dosage rates in terms of each performance parameter were investigated. Two percolation transition zones were identified for CMF in PU matrix at dosage rate ranges of 0.25–1% and 4–10%. The composites exhibited their most desirable performance and properties at CMF dosage rates greater than 10% and smaller than 15%

Feasibility Investigation of Upgrading Gravel Road to Otta Seal Surface: an Economic Analysis Approach

The Norwegian Road Authorities desired that a surface treatment be cost-effective to provide a faster return on investment, perform (as perceived by the road user) in a manner similar to conventional bituminous surfacing, and comply with the following requirements: • Be cheap and easy to implement • Utilize locally-available aggregates • Be impervious to prevent water incursion into moisture-susceptible base material • Be very flexible, durable, and easy to maintain. Such a bituminous surface treatment, referred to as in 1963, and initial field trials were carried out during 1963-1965 in the Otta Valley, Norway. Although Nordic countries, Asia, Africa, New Zealand, and South America have continued to see increasing use of Otta seal (1), its use in the US is currently rather limited due to a lack of knowledge and of the empirical design approach associated with this technique that requires evaluation of trial or demonstration sections before deployment. Minnesota, South Dakota, and Iowa are the only states that have currently completed Otta seal projects in the US, and a summary discussion of MN’s and SD’s experiences with Otta seal is given in this section (2, 3). In this paper, the life cycle cost of surfacing and maintaining an upgraded gravel road to an Otta seal coated surface over a one-mile generic road in Minnesota was evaluated through deterministic and stochastic life-cycle cost analysis (LCCA). Since various road and highway agencies in Minnesota have implemented Otta seal and provided access to the historical cost records needed to complete this study, Minnesota was chosen for a case study for conducting the analysis

Electrically conductive asphalt concrete: An alternative for automating the winter maintenance operations of transportation infrastructure

Hot mix asphalt (HMA) was modified with carbon fiber (CF) to achieve electrically conductive asphalt concrete with applications to pavement anti-icing and de-icing. The volume resistivity of such electrically conductive asphalt concrete was compared with that of electrically conductive asphalt mastic. Then, the temperature increase, the power consumption, and the snow melting capability of electrically conductive asphalt concrete were evaluated. Lastly, a conceptual cost estimation was performed based on data obtained from lab investigations, publicly available bid records, and the experience gained from the field implementation of a heated pavement system made of electrically conductive portland cement concrete

Alterations of the Danger Zone after Preparation of Curved Root Canals Using WaveOne with Reverse Rotation or Reciprocation Movements

Introduction: The aim of this study was to compare the changes that occur in the danger zone (DZ) after preparation of curved mesiobuccal (MB) canals of mandibular first molars with WaveOne instruments in two different movements [reciprocation (RCP) and counter-clockwise rotation (CCWR)] by means of cone-beam computed tomography (CBCT). Methods and Materials: MB canals of 30 mandibular molars were randomly divided into 2 groups (n=15); WaveOne/RCP and WaveOne/CCWR. Pre- and post-instrumentation CBCT images were assessed for changes in the dentin thickness in DZ (2 and 4 mm below the highest point of the root furcation) in both groups. Data was analyzed using the repeated measures ANOVA test. Results: There was no statistically significant difference between two experimental groups in terms of remaining dentin thickness at 2 and 4 mm levels below the highest point of the furcation (P>0.05). Conclusion: The efficacy of WaveOne instrument on changes of the dentin thickness in the DZ was not affected by different file movements.Keywords: Danger Zone; Reciprocating Handpiece; Reciprocation; Rotation; WaveOne