Recombination of asphalt with bio-asphalt : binder formulation and asphalt mixes application

The bio-oil from fast pyrolysis is mainly produced using organic waste materials. This is a viscoelastic material, and after a heat treatment it has a viscosity and high/intermediate thermal rheological behavior similar to many types of asphalt used in the paving industry. These two characteristics show that this material could be a good alternative to replace asphalt. In order to improve the performance of bio-oil, it was hypothesized that the addition of crumb rubber would change the rheology of the modified bio-oil, making it rheologically similar to the conventional paving asphalts. Therefore, two sources of ground rubber from used tires (GTR), from different manufacturing processes, were used to modify the bio-oil. Then, two blends were produced by adding 20% (w/w) of this bio-binder to two different asphalts, a PG58-28 and a PG64-22. The binders were aged, and then storage stability tests (separation sensibility) were performed. The rheology of the initial bio-oil, bio-binder, asphalts and resulting binder-blends were assessed by using a Dynamic Shear Rheometer (DSR), namely by performing frequency sweeps at different temperatures. The results were then used to build the master curves of the materials, and to determine their high temperature continuous performance grade. Additionally, the performance related behavior of mixtures produced with this new material was also assessed, in order to evaluate the advantages of its use in pavements. Therefore, two mixes were produced with the binder that showed better performance regarding thermal rheological behavior, aging susceptibility and separation tendency. These new mixes were finally studied using performance related tests that are able to estimate their future behavior in situ in different environmental and traffic conditions, in particular in regard to water susceptibility, fatigue cracking, dynamic modulus, flow number and low temperature fracture resistance. The results from this first set of experiments showed that this material can perform as well or better than conventional asphalts over a large range of temperatures.FEDER -Federación Española de Enfermedades Rara

Development of an innovative bio-binder using Asphalt-rubber technology

This research work evaluates several parameters that can affect Asphalt Rubber (AR) binder performance and applies the AR technology to the development of an innovative renewable bio-binder that can fully and cost-effectively replace asphaltic bitumen derived from petroleum in flexible pavement construction. The “Binder Accelerated Separator” method was used to divide the constituents of the Asphalt Rubber and bio-binder (residual binder and swelled rubber). The physical and chemical changes in the Asphalt Rubber and bio-binder and in the residual binders (residual bitumen and residual bio-oil) were evaluated. The results demonstrate that the produced bio-binder is suitable for use in flexible pavements with properties comparable to those of conventional and Asphalt Rubber binders

Network analysis reveals open forums and echo chambers in social media discussions of climate change

Open Access articleAction to tackle the complex and divisive issue of climate change will be strongly influenced by public perception. Online social media and associated social networks are an increasingly important forum for public debate and are known to influence individual attitudes and behaviours yet online discussions and social networks related to climate change are not well understood. Here we construct several forms of social network for users communicating about climate change on the popular microblogging platform Twitter. We classify user attitudes to climate change based on message content and nd that social networks are characterised by strong attitude-based homophily and segregation into polarised "sceptic" and "activist" groups. Most users interact only with like-minded others, in communities dominated by a single view. However, we also nd mixed-attitude communities in which sceptics and activists frequently interact. Messages between like-minded users typically carry positive sentiment, while messages between sceptics and activists carry negative sentiment. We identify a number of general patterns in user behaviours relating to engagement with alternative views. Users who express negative sentiment are themselves the target of negativity. Users in mixed- attitude communities are less likely to hold a strongly polarised view, but more likely to express negative sentiment towards other users with di ering views. Overall, social media discussions of climate change often occur within polarising "echo chambers", but also within "open forums", mixed-attitude communities that reduce polarisation and stimulate debate. Our results have implications for public engagement with this important global challenge.Engineering and Physical Sciences Research Council (EPSRC) - Bridging the Gaps initiativ

Development of a rubber-modified fractionated bio-oil for use as noncrude petroleum binder in flexible pavements

The increasing demand for petroleum-derived products coupled with decreasing world crude reserves has led to substantial increases in asphalt pricing. Society’s additional interest in energy independence and use of renewable sources of energy is also a motivation for developing and using more sustainable materials such as binders derived from noncrude petroleum sources for use in highway applications. Iowa State University has been developing noncrude petroleum binders derived from the production of bio-oil via fast pyrolysis of non-food source biorenewable residues. Currently, research has demonstrated that bioasphalt can be used as a modifier, extender, or even as an antioxidant when added to petroleum asphalt. Previous research illustrated concerns with low-temperature cracking and the ability to produce typical binder grades used in the United States. This work aims to develop a biobinder that can replace 100% of the petroleum derived asphalt used in constructing flexible pavements utilizing bio-oil and crumb rubber. Both ambient and cryogenic crumb rubber were used in the research. The outcomes of the processes and formulations illustrates that noncrude petroleum binders can be developed effectively to replace typical paving grades of asphalt such as a PG 64-22 binder

Preliminary Analysis: Am-241 RHU/TEG Electric Power Source for Nanosatellites

The Februay 2013 Space Works Commercial report indicates a strong increase in nano/microsatellite (1-50 kg) launch demand globally in future years. Nanosatellites (NanoSats) are small spacecraft in the 1-10 kg range, which present a simple, low-cost option for developing quickly-deployable satellites. CubeSats, a special category of NanoSats, are even being considered for interplanetary missions. However, the small dimensions of CubeSats and the limited mass of the NanoSat class in general place limits of capability on their electrical power systems (especially where typical power sources such as solar panels are considered) and stored energy reserves; restricting the power budget and overall functionality. For example, leveraging NanoSat clusters for computationally intensive problems that are solved collectively becomes more challenging with power related restrictions on communication and data-processing. Further, interplanetary missions that would take NanoSats far from the sun, make the use of solar panels less effective as a power source as their required area would become quite large. To overcome these limitations, americium 241 (Am-241) has been suggested as a low power source option. The Idaho National Laboratory, Center for Space Nuclear Research reports that: (Production) requires small quantities of isotope - 62.5 g of Pu-238; 250 g Am- 241 (for 5 We); Am-241 is available at around 1 kg/yr commercially; Am-241 produces 59 kev gammas which are stopped readily by tungsten so the radiation field is very low. Whereby, an Am-241 source could be placed in among the instruments and the waste heat used to heat the platform; and amounts of isotope are so low that launch approval may be easier, especially with tungsten encapsulation. As further reported, Am-241 has a half-life that is approximately five times greater than that of Pu- 238 and it has been determined that the neutron yield of a 241-AmO(sub 2) source is approximately an order of magnitude lower than that of a 238-PuO(sub 2) source of equal mass and degree of (sup 16)O enrichment. Also it has been demonstrated that shielded heat sources fuelled by oxygen-enriched 238-PuO(sub 2) have masses that are up to 10 times greater than those fuelled by oxygenenriched 241-AmO(sub 2) with equivalent thermal power outputs and neutron dose rates at 1 m radii. For these reasons, Am-241 is well suited to missions that demand long duration electrical power output, such as deep spaceflight missions and similar missions that use radiation-hard electronics and instrumentation that are less susceptible to neutron radiation damage

Teleseisms monitoring using chirped-pulse φOTDR

Monitoring of seismic activity around the word is a topic of high interest for the analysis and understanding of deep Earth dynamics. However, the deployment of a homogeneous network of seismic stations both onshore and offshore poses a strong economic challenge that makes this solution practically inviable. Using the pre-existing fiber optical network for seismic monitoring arises as an excellent solution with important advantages in terms of ubiquity and cost. In this communication, we present the detection of an M8.2 earthquake occurred in Fiji Island using distributed acoustic sensing based on chirped-pulse φOTDR. Two sensors were placed simultaneously at two different locations at >9,000 km from the earthquake epicenter: a metropolitan area and a submarine environment. The recorded data is postprocessed using a 2D linear filter to cancel out environmental noise. The resulting signals are compared with the signals acquired by nearby seismometers. The attained good matching between the recorded data and the seismometer data shows the strong potential of the use of the already-deployed communication fiber network for teleseism monitoring

Impedance spectroscopy characterization of neutron irradiated thermoelectric modules for space nuclear power

The European Space Agency is currently supporting the research and development of advanced radioisotope power systems utilising thermoelectric modules. The performance of thermoelectric modules following exposure to neutron radiation is of significant interest due to the likely application of radioisotope thermoelectric generators in deep space exploration or planetary landers requiring prolonged periods of operation. This study utilises impedance spectroscopy to characterise the effects of neutron irradiation on the performance of complete thermoelectric modules, as opposed to standalone material. For a 50 We americium-241 radioisotope thermoelectric generator design, it is estimated that the TE modules could be exposed to a total integrated flux of approximately 5 × 1013 neutrons cm-2 (>1 MeV). In this study, an equivalent neutron dose was simulated experimentally via an acute 2-hour exposure in a research pool reactor. Bi2Te3-based thermoelectric modules with different leg aspect ratios and microstructures were investigated. Gamma-ray spectroscopy was initially used to identify activated radionuclides and hence quantify irradiation induced transmutation doping. To evaluate the thermoelectric properties pre- and post-irradiation, impedance spectroscopy characterization was employed. Isochronal thermal annealing of defects imparted by the irradiation process, revealed that polycrystalline based modules required significantly higher temperature than those with a monolithic microstructure. Whilst this may indicate a greater susceptibility to neutron irradiation, all tested modules demonstrated sufficient radiation hardness for use within an americium-241 radioisotope thermoelectric generator. Furthermore, the work reported demonstrates that impedance spectroscopy is a highly capably diagnostic tool for characterising the in-service degradation of complete thermoelectric devices

Distributed acoustic sensing for seismic activity monitoring

Continuous, real-time monitoring of surface seismic activity around the globe is of great interest for acquiring new insight into global tomography analyses and for recognition of seismic patterns leading to potentially hazardous situations. The already-existing telecommunication fiber optic network arises as an ideal solution for this application, owing to its ubiquity and the capacity of optical fibers to perform distributed, highly sensitive monitoring of vibrations at relatively low cost (ultra-high density of point sensors available with minimal deployment of new equipment). This perspective article discusses early approaches on the application of fiber-optic distributed acoustic sensors (DASs) for seismic activity monitoring. The benefits and potential impact of DAS technology in these kinds of applications are here illustrated with new experimental results on teleseism monitoring based on a specific approach: the so-called chirped-pulse DAS. This technology offers promising prospects for the field of seismic tomography due to its appealing properties in terms of simplicity, consistent sensitivity across sensing channels, and robustness. Furthermore, we also report on several signal processing techniques readily applicable to chirped-pulse DAS recordings for extracting relevant seismic information from ambient acoustic noise. The outcome presented here may serve as a foundation for a novel conception for ubiquitous seismic monitoring with minimal investment

Distributed acoustic sensing for seismic activity monitoring

Continuous, real-time monitoring of surface seismic activity around the globe is of great interest for acquiring new insight into global tomography analyses and for recognition of seismic patterns leading to potentially hazardous situations. The already-existing telecommunication fiber optic network arises as an ideal solution for this application, owing to its ubiquity and the capacity of optical fibers to perform distributed, highly sensitive monitoring of vibrations at relatively low cost (ultra-high density of point sensors available with minimal deployment of new equipment). This perspective article discusses early approaches on the application of fiber-optic distributed acoustic sensors (DASs) for seismic activity monitoring. The benefits and potential impact of DAS technology in these kinds of applications are here illustrated with new experimental results on teleseism monitoring based on a specific approach: the so-called chirped-pulse DAS. This technology offers promising prospects for the field of seismic tomography due to its appealing properties in terms of simplicity, consistent sensitivity across sensing channels, and robustness. Furthermore, we also report on several signal processing techniques readily applicable to chirped-pulse DAS recordings for extracting relevant seismic information from ambient acoustic noise. The outcome presented here may serve as a foundation for a novel conception for ubiquitous seismic monitoring with minimal investment