9 results on '"John Cotter"'
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2. Reinforced, Nailable Rubber Concrete with Strength and Withdrawal Properties Similar to Lumber
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John Cotter and Rasim Guldiken
- Subjects
rubber concrete ,rubbercrete ,concrete fasteners ,pullout tests ,withdrawal tests ,Technology ,Science - Abstract
The inclusion of rubber in concrete has been suggested and used in recent research. However, the reason for the inclusion of rubber into concrete is typically the need to offset the carbon footprint of concrete and other environmental concerns. The research presented here indicates that the inclusion of rubber into concrete allows for the concrete to accept fasteners and withstand withdrawal, or pullout, of the fasteners, similar to the function of wood. We refer to this as making the concrete “nailable”, in that the concrete can be nailed together either by hand or with tools designed to be used with wood. While other methods have been used to make concrete nailable, this method is novel as no known research exists indicating that there exists a rubber concrete mix that provides similar withdrawal strength as wood. Testing indicates that the concrete can be produced at a low cost due to the inclusion of the low-cost rubber infill with reinforcement wire. The result is a reinforced concrete with an allowable load that is 13% greater than in spruce and a withdrawal force up to 25% greater than the maximum in spruce. The intended function of this material is replacement of treated lumber. The proposed rubber concrete, which is a reinforced concrete, is anticipated to have a service life of 50–100 years, while treated lumber decks in the Southeastern United States have been surveyed to have an average life of only 10 years due to environmental degradation. This leads us to conclude that if a deck were to be constructed of this nailable rubber concrete, it would last approximately five times longer in a temperate environment, such as the Southeastern United States. This improvement can be provided at a relatively low cost while providing an alternative that both prevents the use of arsenic- and copper-containing compounds used in treated lumber and provides an additional recycling method for tires.
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- 2023
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3. Bulk Glass Reinforced Composite Columns: Physical Testing Results, Analysis, and Discussion
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John Cotter and Rasim Guldiken
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bulk glass reinforcement ,glass reinforced composite columns ,column buckling ,Technology ,Science - Abstract
Glass-reinforced composite columns (GRCCs) may provide an economical alternative to conventional construction materials due to the superior cost to strength provided by bulk glass. Prior to this study, no GRCCs had been physically tested, having previously relied on simulation to predict the behavior of the columns. This study utilizes polyurethane resin bonds in place of sizing agents for adherence between materials, a key requirement for the development of the structural system of the columns. The unreinforced control column failed at a load of 11.2 kN while the maximum GRCC load was 30.8 kN. This indicates that glass can be loaded to 123 MPa before the onset of delamination failure of the GRCCs. Maximum shear stress of 53 MPa was reached, exceeding the 11 MPa required for practical GRCCs. Buckling of the columns occurred at 30.8 kN, below the theoretical maximum of 64.4 kN. Through gradual delamination, the column slowly transferred to an unbonded condition, causing buckling failure. Delamination is unlikely to occur in practical GRCCs due to the lower required shear strengths.
- Published
- 2023
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4. Cost-Effective Bulk Glass Reinforced Composite Columns
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John Cotter and Rasim Guldiken
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bulk glass reinforcement ,glass reinforced composite columns ,Technology ,Science - Abstract
The cost of construction has been increasing, stemming mostly from increased material costs. One potential method to address this issue is the introduction of novel composites for use in structural applications. Bulk glass may prove to be a superior compositing material due to its low cost and high strength. The introduction of bulk soda-lime glass to structural applications is nontrivial; due to glass’ unique properties, such as its relatively low Young’s modulus (when compared to steel) and brittleness, compositing glass has proven difficult. A novel concept of a glass-reinforced composite column (GRCC) is introduced that works to benefit from glass’ unique properties for structural applications. The results indicate that GRCCs can be designed that have costs that are estimated to be 11% less than typical timber construction members. Additionally, GRCCs are estimated to provide a 50% cost advantage over similarly strong structural steel sections. By interpreting the results of finite element modeling, which was conducted iteratively to form buckling load to cost curves, three regions were identified that occur as the glass percentage is increased. These regions also exist with columns made of other materials (such as steel). Additionally, the finite element modeling (FEM)-determined shear stresses have smaller values than the shear strengths of typical sizing agents. In conclusion, GRCCs provide significant cost advantages (up to 50% cost reduction) over steel, and slight cost advantages when compared to structural timbers, although GRCCs have the added benefit of consisting of non-degrading materials.
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- 2020
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5. Theoretical Design Strategies, Strengths, Costs, and Environmental Impacts of Triple Composite Beams Utilizing Glass Compressive Reinforcement
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John Cotter and Rasim Guldiken
- Subjects
glass reinforcement ,transformed sections method ,euler–bernoulli beam theory ,composite beam ,Technology ,Science - Abstract
Due to increasing costs and growing environmental concerns pertaining to the construction of structures, an alternative form of reinforcement has been proposed through our studies; through a new beam design methodology, referred to as triple composite beams, glass can be used as a cost-competitive and more environmentally friendly macro-scale compressive reinforcement. The cost competitiveness of glasses derives from their large compressive strength (in general 1000 MPa; >1100 MPa for fused quartz). To support the triple composite design architecture, equations have been developed using Euler−Bernoulli beam theory and the method of transformed sections and compared against finite element modeling determined stresses. Our results show that the average stress was more accurate but less precise than fully considering binder, assuming the binder did not contribute to the cross-section of the beam. The paper concludes by presenting a flexural reinforcement utilization ratio (R), which predicts the ability of a reinforcement-binder combination to utilize the reinforcement to maximum stress effectively while ignoring bonding strength. This R ratio suggests that while concrete is a low cost, it cannot be used in a glass-reinforced beam as the concrete is too stiff compared to the glass.
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- 2020
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6. Untying the Ties that (don’t) Bind
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John Cotter
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Article 265 TFEU, Babis, Charles Michel, EU, European Council, Orban, Rule of Law, Wagenknecht ,Law - Abstract
In his letter to MEP Daniel Freund of 17 June 2022, European Council President Charles Michel argued that neither he, as President, nor the European Council have the power to exclude democratically unaccountable representatives of a Member State from that institution. But President Michel’s apparent recourse to a literal reading of Article 15(2) TEU – which fails to consider its relationship with other provisions relating to the composition of the European Council – is not convincing.
7. The Last Chance Saloon
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John Cotter
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Art. 10 TEU, democracy, Emergency, Rule of Law, Viktor Orban ,Law - Abstract
To all intents and purposes, Orbán and his government have ceased to be democratically accountable either to the Hungarian Parliament or to the citizens of Hungary. The words in that last sentence are chosen carefully and with meaning. This blogpost suggest that Article 10 TEU may provide a basis for the exclusion of Hungarian representatives from the European Council and the Council of the European Union.
8. Monte Carlo modelling of a prototype small-body portable graphite calorimeter for ultra-high dose rate proton beams
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John Cotterill, Sam Flynn, Russell Thomas, Anna Subiel, Nigel Lee, David Shipley, Hugo Palmans, and Ana Lourenço
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Dosimetry ,Proton ,FLASH ,UHDR ,Monte Carlo ,Calorimetry ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Background and purpose: Accurate dosimetry in Ultra-High Dose Rate (UHDR) beams is challenging because high levels of ion recombination occur within ionisation chambers used as reference dosimeters. A Small-body Portable Graphite Calorimeter (SPGC) exhibiting a dose-rate independent response was built to offer reduced uncertainty on secondary standard dosimetry in UHDR regimes. The aim of this study was to quantify the effect of the geometry and material properties of the device on the dose measurement. Materials and methods: A detailed model of the SPGC was built in the Monte Carlo code TOPAS (v3.6.1) to derive the impurity and gap correction factors, kimp and kgap. A dose conversion factor, DwMC/DgMC, was also calculated using FLUKA (v2021.2.0). These factors convert the average dose to its graphite core to the dose-to-water for a 249.7 MeV mono-energetic spot-scanned clinical proton beam. The effect of the surrounding Styrofoam on the dose measurement was examined in the simulations by substituting it for graphite. Results: The kimp and kgap correction factors were 0.9993 ± 0.0002 and 1.0000 ± 0.0001, respectively when the Styrofoam was not substituted, and 1.0037 ± 0.0002 and 0.9999 ± 0.0001, respectively when substituted for graphite. The dose conversion factor was calculated to be 1.0806 ± 0.0001. All uncertainties are Type A. Conclusions: Impurity and gap correction factors, and the dose conversion factor were calculated for the SPGC in a FLASH proton beam. Separating out the effect of scatter from Styrofoam insulation showed this as the dominating correction factor, amounting to 1.0043 ± 0.0002.
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- 2023
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9. Absolute dosimetry for FLASH proton pencil beam scanning radiotherapy
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Ana Lourenço, Anna Subiel, Nigel Lee, Sam Flynn, John Cotterill, David Shipley, Francesco Romano, Joe Speth, Eunsin Lee, Yongbin Zhang, Zhiyan Xiao, Anthony Mascia, Richard A. Amos, Hugo Palmans, and Russell Thomas
- Subjects
Medicine ,Science - Abstract
Abstract A paradigm shift is occurring in clinical oncology exploiting the recent discovery that short pulses of ultra-high dose rate (UHDR) radiation—FLASH radiotherapy—can significantly spare healthy tissues whilst still being at least as effective in curing cancer as radiotherapy at conventional dose rates. These properties promise reduced post-treatment complications, whilst improving patient access to proton beam radiotherapy and reducing costs. However, accurate dosimetry at UHDR is extremely complicated. This work presents measurements performed with a primary-standard proton calorimeter and derivation of the required correction factors needed to determine absolute dose for FLASH proton beam radiotherapy with an uncertainty of 0.9% (1 $$\sigma$$ σ ), in line with that of conventional treatments. The establishment of a primary standard for FLASH proton radiotherapy improves accuracy and consistency of the dose delivered and is crucial for the safe implementation of clinical trials, and beyond, for this new treatment modality.
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- 2023
- Full Text
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