The global and U.S. domestic effort to develop a clean energy economy and curb environmental pollution incentivizes the use of hydrogen as a transportation fuel, owing to its zero tailpipe pollutant ...emissions and high fuel efficiency in fuel cell electric vehicles (FCEVs). However, the hydrogen production process is not emissions free. Conventional hydrogen production via steam methane reforming (SMR) is energy intensive, coproduces carbon dioxide, and emits air pollutants. Thus, it is necessary to quantify the environmental impacts of SMR hydrogen production alongside the use-phase of FCEVs. This study fills the information gap, analyzing the greenhouse gas (GHG) and criteria air pollutant (CAP) emissions associated with hydrogen production in U.S. SMR facilities by compiling and matching the facility-reported GHG and CAP emissions data with facilities’ hydrogen production data. The actual amounts of hydrogen produced at U.S. SMR facilities are often confidential. Thus, we have developed four approaches to estimate the hydrogen production amounts. The resultant GHG and CAP emissions per MJ of hydrogen produced in individual facilities were aggregated to develop emission values for both a national median and a California state median. This study also investigates the breakdown of facility emissions into combustion emissions and noncombustion emissions.
This paper reports an experimental investigation of the mechanical properties of cold-formed lean duplex stainless steel after exposure to high temperatures up to 1000 °C. The test specimens were ...extracted from rectangular and square hollow sections that were cold-rolled from flat plates of lean duplex stainless steel. The mechanical properties, Young's modulus, yield strength, ultimate strength, Ramberg-osgood parameter and strain at ultimate strength of lean duplex stainless steel, are reported. The residual mechanical properties of steel materials are compared with the predicted values calculated by the existing equations. It is shown that the existing equations cannot provide accurate predictions for the post-fire mechanical properties of lean duplex stainless steel materials. Thus, a unified equation is proposed to predict residual mechanical properties for lean duplex stainless steel specimens in post-fire conditions. A constitutive model is also proposed to predict the stress-strain relationship of the test specimens after exposure to high temperatures up to 1000 °C. A reliability analysis was conducted for the proposed equation. The proposed equation compared favourably with the experimental results, and was found to be reliable for predicting lean duplex stainless steel mechanical properties after exposure to high temperatures.
•Investigation on lean duplex stainless steel post-fire properties was performed.•Effects of exposed temperature ranged from 24 to 1000 ºC and soak time are investigated.•Existing design rules are assessed by comparing test results.•Design rules to predict residual mechanical properties were proposed.•Constitutive model to predict stress-strain curves after fire exposure was proposed.
•Simply supported bending tests on aluminium alloy hollow sections were performed.•Finite element models were developed and validated against the test results.•A parametric study on cross-section ...slendernesses was performed.•Moment capacities predicted by the design specifications are overly conservative.•The CSM provides more accurate and consistent predictions.
Two series of simply supported bending tests on aluminium alloy square and rectangular hollow sections have been performed. The test program comprised 14 three-point bending tests and 15 four-point bending tests. The test specimens were fabricated by extrusion from grades 6061-T6 and 6063-T5 heat-treated aluminium alloys, with width-to-thickness ratios ranging from 2.8 to 20.5. Measured geometric and material properties, together with the full load–deflection histories from the test specimens, were reported. Observed failure modes included local buckling, material yielding and tensile fracture. Further experimental data were gathered from the literature. Finite element (FE) models were developed and validated against the test results, and then used to perform parametric studies, in which a total of 132 numerical results were generated. The experimental and numerical results were used to evaluate the bending resistance provisions of the American 1, Australian/New Zealand 2 and European 3 Specifications, as well as the continuous strength method (CSM). The moment capacities predicted by the three design specifications were found to be generally conservative, while the CSM provided more accurate and more consistent predictions due to the recognition and systematic exploitation of strain hardening.
This paper investigates the behaviour of pin-ended axially loaded concrete encased steel composite columns. A nonlinear 3-D finite element model was developed to analyse the inelastic behaviour of ...steel, concrete, longitudinal and transverse reinforcement bars as well as the effect of concrete confinement of the concrete encased steel composite columns. The interface between the steel section and concrete, the longitudinal and transverse reinforcement bars, and the reinforcement bars and concrete were also considered that allowed the bond behaviour to be modeled and the different components to retain their profile during the deformation of the column. Furthermore, the initial overall (out-of-straightness) geometric imperfection was carefully incorporated in the model. The finite element model has been validated against published experimental results. The main objective of the study was to understand the structural response and modes of failure of the columns and to assess the composite column strengths against current design codes. The study covered slender, non-slender, stub and long concrete encased steel composite columns. The concrete strengths varied from normal to high strength (20–110 MPa). The steel section yield stresses also varied from normal to high strength (275–690 MPa). Furthermore, the variables that influence the composite column behaviour and strength comprising different slenderness ratios, concrete strength and steel yield stress were investigated in a parametric study. It is shown that the increase in structural steel strength has a small effect on the composite column strength for the columns having higher relative slenderness ratios due to the flexural buckling failure mode. The composite column strengths obtained from the finite element analysis were compared with the design strengths calculated using the American Institute for Steel Construction AISC and Eurocode 4 for composite columns. Generally, it is shown that the EC 4 accurately predicted the design strength for the concrete encased steel composite columns having a concrete cylinder strength of 30 MPa and structural steel yield stresses of 275 and 460 MPa, which are in the limits of the code, which otherwise, was generally conservative. The AISC predictions were quite conservative for all the concrete encased steel composite columns.
The use of fibre-reinforced polymer (FRP) composites is becoming increasingly widespread in civil infrastructure for strengthening and repair applications as well as whole FRP members and structures. ...A question which, however, continually arises from all stake-holders is the performance of FRP materials under elevated temperatures. An accurate understanding of the material properties and behaviour of FRP at such high temperatures is crucial, and they are necessary pieces of information that are surprisingly scarce in the literature. This paper therefore presents the mechanical properties of pultruded carbon fibre-reinforced polymer (CFRP) plates at elevated temperatures. More specifically, CFRP pultruded plate coupons were tested at steady and transient states for temperatures ranging from approximately 20 to 700 °C. The tests showed that, for the temperature ranges 20–150 °C and 450–706 °C, reductions of the tensile strength of the pultruded CFRP plate occurred. Between these temperature ranges, the tensile strength decreased by a small amount, while at 300 °C the ultimate strength was approximately 50% of the room-temperature strength. In addition, the tensile strength of the plate was as low as 7% of the room-temperature tensile strength at the approximate peak temperature of 700 °C. Finally, an equation that relates the tensile strength of the plate to the entire tested temperature range which has been calibrated with all the test data is proposed.
Early detection of cancer through organized screening is a central component of population-level strategies to reduce cancer mortality. For screening programs to be effective, it is important that ...those invited to screening participate. However, uptake rates are suboptimal in many populations and vary between screening programs, indicating a complex combination of patient factors that require elucidation to develop evidence-based strategies to increase participation. In this review, the authors summarize individual-level (sociodemographic and psychosocial) factors associated with cancer screening uptake and evidence for the effectiveness of behavioral interventions to increase uptake. The authors reflect on current trends and future directions for behavioral cancer screening research to overcome challenges and address unmet needs in reducing cancer mortality.
This paper presents the mechanical properties of high strength structural steel and mild structural steel at elevated temperatures. Mechanical properties of structural steel at elevated temperatures ...are important for fire resistant design of steel structures. However, current design standards for fire resistance of steel structures are mainly based on the investigation of hot-rolled carbon steel with normal strength, such as mild steel. The performance of high strength steel at elevated temperatures is unknown. Hence, an experimental program has been carried out to investigate the mechanical properties of both high strength steel and mild steel at elevated temperatures. The high strength steel BISPLATE 80 (approximately equivalent to ASTM A 514, EN 10137-2 Grade S690Q, and JIS G 3128) and the mild steel XLERPLATE Grade 350 (approximately equivalent to ASTM 573-450) were tested using steady and transient-state test methods. The elastic moduli and yield strengths were obtained at different strain levels, and the ultimate strength and thermal elongation were evaluated at different temperatures. It is shown that the reduction factors of yield strength and elastic modulus of high strength steel and mild steel are quite similar for the temperature ranging from
22
to
540°C
. The test results were compared with the predictions obtained from the American, Australian, British, and European standards.
Paleoseismic work completed at Hog Lake on the San Jacinto Fault (SJF) near Anza, California, indicates that at least 21 surface ruptures have occurred in the Anza Seismic gap over the past ...4,000 years. The ages of the ruptures are constrained by 111 radiocarbon dates, 97 of which fall in stratigraphic order. The average recurrence interval for all ruptures for this period is about 185 ± 105 years, although some ruptures, such as occurred in the April 1918 earthquake, caused only minor displacement. We rate the expression of each interpreted event in each of the twelve developed field exposures presented in this work by assigning numeric values for the presence of different criteria that indicate rupture to a paleo-ground surface. Weakly expressed ruptures, for example the deformation we interpret to be the result of the historical 1918 earthquake, received low scores and are interpreted as smaller earthquakes. From this analysis, we infer that at least fifteen of the identified ruptures are indicative of large earthquakes similar to the penultimate earthquake, inferred to be the
M
w
7.3 22 November 1800 earthquake. The adjusted recurrence interval for large earthquakes lengthens to approximately 254 years. Comparison with the rupture history at the Mystic Lake paleoseismic site on the Claremont strand indicates that it is plausible that several of the large ruptures identified at Hog Lake could have jumped the Hemet step-over at Mystic Lake and continued on the Claremont strand (or vice versa), but most of the event ages do not match between the two sites, indicating that most ruptures do not jump the step. Finally, comparison with San Andreas Fault ruptures both to the north and south of its juncture with the SJF suggest that some northern SJF ruptures identified at Mystic Lake may correlate with events identified at Wrightwood, but that these northern ruptures have no match at Hog Lake and can not indicate rupture of the entire SJF onto the SAF.
•Web crippling behaviour at elevated temperatures has been modelled.•The current web crippling design rules has been examined at elevated temperatures.•A unified web crippling equation at elevated ...temperatures has been proposed.•Numerical data were compared with proposed design strengths at high temperatures.•Test strengths were compared with proposed design strengths at room temperature.
This paper reports a numerical investigation of cold-formed high strength stainless steel square and rectangular hollow sections subjected to web crippling at elevated temperatures. Finite element analysis was conducted on cold-formed high strength austenitic and duplex stainless steel material. Four loading conditions specified in the American Specification and Australian/New Zealand Standard for cold-formed stainless steel structures were investigated in the numerical study. A non-linear finite element model which includes geometric and material non-linearities was developed and verified against experimental results. It was shown that the finite element model closely predicted the web crippling strengths and failure modes of the tested specimens under the four loading conditions. Hence, parametric study was carried out to investigate the web crippling behaviour of cold-formed high strength stainless steel square and rectangular hollow sections at elevated temperatures. The web crippling strengths predicted from the finite element analysis were compared with the design strengths obtained using the American, Australian/New Zealand and European specifications for stainless steel structures by substituting the reduced material properties in the current web crippling design equations. A unified web crippling equation for cold-formed high strength stainless steel square and rectangular hollow sections at elevated temperatures is proposed. It is demonstrated that the web crippling strength obtained using the proposed equation is safe and reliable using reliability analysis.
IntroductionScreening can reduce deaths from colorectal cancer (CRC). Despite high levels of public enthusiasm, participation rates in population CRC screening programmes internationally remain ...persistently below target levels. Simple behavioural interventions such as completion goals and planning tools may support participation among those inclined to be screened but who fail to act on their intentions. This study aims to evaluate the impact of: (a) a suggested deadline for return of the test; (b) a planning tool and (c) the combination of a deadline and planning tool on return of faecal immunochemical tests (FITs) for CRC screening.Methods and analysisA randomised controlled trial of 40 000 adults invited to participate in the Scottish Bowel Screening Programme will assess the individual and combined impact of the interventions. Trial delivery will be integrated into the existing CRC screening process. The Scottish Bowel Screening Programme mails FITs to people aged 50–74 with brief instructions for completion and return. Participants will be randomised to one of eight groups: (1) no intervention; (2) suggested deadline (1 week); (3) suggested deadline (2 weeks); (4) suggested deadline (4 weeks); (5) planning tool; (6) planning tool plus suggested deadline (1 week); (7) planning tool plus suggested deadline (2 weeks); (8) planning tool plus suggested deadline (4 weeks). The primary outcome is return of the correctly completed FIT at 3 months. To understand the cognitive and behavioural mechanisms and to explore the acceptability of both interventions, we will survey (n=2000) and interview (n=40) a subgroup of trial participants.Ethics and disseminationThe study has been approved by the National Health Service South Central—Hampshire B Research Ethics Committee (ref. 19/SC/0369). The findings will be disseminated through conference presentations and publication in peer-reviewed journals. Participants can request a summary of the results.Trial registration number clinicaltrials.govNCT05408169
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