Determing the Effect of Thermal Treatment Timing on Ultra-High Performance Concrete Beams

The loss of prestressing force over time influences the long-term deflection of the prestressed concrete element. Prestress losses are inherently complex due to the interaction of concrete creep, concrete shrinkage, and steel relaxation. Implementing advanced materials such as ultra-high performance concrete (UHPC) further complicates the estimation of prestress losses because of the changes in material models dependent on curing regime. Past research shows compressive creep is locked in when UHPC cylinders are subjected to thermal treatment before being loaded in compression. However, the current precasting manufacturing process would typically load the element (through prestressing strand release from the prestressing bed) before the element would be taken to the curing facility. Members of many ages are stored until curing could be applied to all of them at once. This research was conducted to determine the impact of variable curing times for UHPC on the prestress losses, and hence deflections. Three UHPC beams, a rectangular section, a modified bulb tee section, and a pi-girder, were assessed for losses and deflections using an incremental time step approach and material models specific to UHPC based on compressive creep and shrinkage testing. Results show that although it is important for prestressed UHPC beams to be thermally treated, to lock in material properties, the timing of thermal treatment leads to negligible differences in long-term deflections. Results also show that for UHPC elements that are thermally treated, changes in deflection are caused only by external loads because prestress losses are locked-in following thermal treatment

Linearly polarised pion photoproduction on the deuteron

Measurements of the linear polarisation asymmetry in pion photoproduction on both the proton and neutron have been performed with a liquid deuterium target using the Mainzer Microtron and Crystal Ball detector at the Johannes Gutenberg Universität in Mainz. These results, particularly the π 0 n channel, provide current models attempting to describe the nucleon resonance spectrum and properties with essential constraints. Measurements on the neutron are essential to determine isospin amplitudes of the nucleon resonance spectrum. The experiment featured a photon beam polarised through coherent bremsstrahlung of a 1.5 GeV electron beam on an aligned diamond radiator. The target was cryogenic liquid deuterium cooled to 23 K. Detection of the produced π 0 s was achieved through their dominant decay to two photons which were subsequently recorded in high density scintillating crystal calorimeters, known as the Crystal Ball and TAPS. The same detectors were used to determine the direction of the recoiling proton or neutron while thin plastic scintillator was used to distinguish between the two nucleons. Results on the proton are consistent with previous measurements and predictions from groups performing partial wave analysis to determine the resonance properties. Results on the neutron are measured for the first time in this energy regime spanning the first and second resonance regions and favour the SAID partial wave analysis solution

Mid-Level Student Affairs Professionals Worklife Negotiation and the Use of Mobile Technology: A Case Study

The mainstream media and academic research have covered worklife balance increasingly over the last couple of decades. Worklife balance, the notion that one’s work and life domains are equal, is a challenge for most working professionals. It has become even more significant with the prevalence of mobile technology such as smartphones and the continuously connected society in which we live. Student affairs professionals are not immune to worklife balance issues, particularly because they are in a field in which there are long hours and night and weekend work. This dissertation study uses work/family border theory to consider the following research question: How do mid-level student affairs professionals describe their worklife negotiation experiences with the use of mobile technology? In this study, the terms balance and negotiation are not interchangeable. Through a single-case study at one university, I conducted ten interviews with ten mid-level student affairs professionals and two overarching themes arose from the data - organizational and personal factors that impact worklife balance. Organizational factors included the subthemes of institutional or departmental culture, supervisor support, an employee’s schedule flexibility, level of staffing, and supervision. The personal factor subthemes were family, mobile technology, navigating boundaries, fear of missing out, and self-care. A discussion of implications for student affairs professionals, supervisors, student affairs administrators, and human resources professionals is provided in Chapter V. The implications section includes items like student affairs professionals need to have a better understanding of the worklife balance needs and supervisors play a large role in a student affairs professional’s worklife balance through approving time off and schedules and getting to know and understand an individual’s worklife balance needs. In addition, student affairs administrators should intentionally develop an organizational culture that supports worklife balance and human resources professionals can support an employee’s worklife balance through well thought out policies, procedures, and trainings that develop supervisors and employees in the area of worklife balance. Finally, I provide direction for future research on worklife negotiation and mobile technology use and boundaries in student affairs

A polymer coated cicaprost-eluting stent increases neointima formation and impairs vessel function in the rabbit iliac artery

Drug-eluting stents have been successful in reducing in-stent restenosis but are not suitable for all lesion types and have been implicated in causing late stent thrombosis due to incomplete regeneration of the endothelial cell layer. In this study we implanted stents coated with cicaprost, a prostacyclin analogue with a long plasma half-life and antiproliferative effects on vascular smooth muscle cells, into the iliac arteries of rabbits. At 28-day follow-up we compared neointima formation within the stented vessels and vascular function in adjacent vessels, to assess if cicaprost could reduce restenosis without impairing vessel function. Arteries implanted with cicaprost eluting stents had significantly more neointima compared to bare metal stents. In adjacent segments of artery, endothelium-dependent relaxation was impaired by the cicaprost-eluting stent but vasodilation to an endothelium-independent vasodilator was maintained. We conclude that the presence of the polymer and sub-optimal release of cicaprost from the stent may be responsible for the increased neointma and impaired functional recovery of the endothelium observed. Further experiments should be aimed at optimising release of cicaprost and exploring different stent polymer coatings

Introduction : Judicial Review at thirty

There is nothing quite like an anniversary to provoke reflection: about where we have come from, about where we find ourselves; and, inevitably, about where next we might be headed. Taking as their cue the thirtieth anniversary of the introduction of rule 260B to the Rules of Court, the essays gathered in this special edition each, in their own way, attempt to address these questions as they relate to the practice and the evolution of judicial review in Scotland

Femtosecond Laser Photoionization Time-of-Flight Mass Spectrometry of Nitro-aromatic Explosives and Explosives Related Compounds

The ultrafast laser-induced photoionization and photodissociation processes of the nitroaromatic containing explosive and explosive related compounds (ERCs) nitrobenzene (NB), 1,3-dinitrobenzene (DNB), m-nitrotoluene (MNT), 2,4-dinitrotoluene (DNT), and 2,4,6-trinitrotoluene (TNT) have been investigated at three laser wavelengths and power densities using a time-of-flight mass spectrometer. Examination of the mass spectra of these compounds reveals the enhanced formation of the molecular ion [M+] when ultraviolet (332 nm) and visible (495 nm) light is used relative to infrared (795 nm) radiation. In addition, at 795 nm and a power density of 3.5 × 1014 W/cm2, the presence of a competition between multiphoton ionization (MPI) and Coulomb explosion (CE) channels is revealed by peak shape analysis, and is thought to be operative under these conditions for all of the molecules investigated

Interactions between demand side response, demand recovery, peak pricing and electricity distribution network capacity margins

PhD ThesisThe operation of the electricity system is subject to: charges comprised of energy, capacity, use of system, peak demand and balancing components; payments for services that influence the timing and magnitude of demand; and regulatory and physical network constraints. This work explores the interactions of these characteristics in the GB system. The revenue flows associated with energy demand, balancing and use of system charges are mapped for generators, transmission and distribution network operators (TNO and DNOs), system operator (SO), electricity retailers and electricity users. Triads are part of the transmission network use of service charges and are a form of peak demand pricing. The cost-benefit of Triad avoidance using emergency standby generation is evaluated. Demand Side Response (DSR) provision by commercial electricity users on the network is modelled and simulated. The research determines the impacts of DSR timing, location and penetration level, demand recovery and incidence of Triad periods. A suite of software models was developed including: network demand agents which can be populated with demand profiles and include a model of energy recovery; an interface to Matpower [1] to allow for time-domain based power flow calculations and a model of Short Term Operating Reserve (STOR) which synthesizes calls at representative dates and times. The network demand agents are linked to bus-bars on a network model. The software suite is used to investigate the impacts of STOR provision by demand reduction with and without energy recovery on Triad demand using a Monte Carlo simulation. The total cost benefit of participation in STOR is evaluated. It is also used to conduct timeaware power-flow analysis on a distribution network model with STOR provision by demand reduction. The impact on network capacity headroom is quantified. The cost effectiveness of using standby generation for Triad avoidance was found to depend on the cost of the grid compliant connection. For a payback time of 4 years or less, with the size of generator considered, the grid compliant connection would have to cost less than £5,600. The probability of decreased Triad demand due STOR provision by demand reduction with energy recovery is up to 4 % for the parameters considered. This compares to a probability of up to 1.6 % that the Triad demand would be increased. The most likely outcome is that Triad demand remains unaffected. The total cost benefit of STOR Abstract 2 provision by demand reduction for the 1st percentile may be negative compared to not participating. The impact of DSR provision by demand reduction with energy recovery on the distribution network capacity overhead varies significantly with time of day and with the distribution of DSR over the network. For evenly distributed DSR, demand recovery peaks greater than 40 kW cause a reduction in capacity overhead. However, for a case where the DSR is not evenly distributed the capacity overhead does not decrease for recovery peaks less than 800 kW.Engineering and Physical Sciences Research Council (EPSRC) and Siemen

Windows into Non-Euclidean Spaces

Two microlens arrays that are separated by the sum of their focal lengths form arrays of micro-telescopes. Parallel light rays that pass through corresponding lenses remain parallel, but the direction of the transmitted light rays is different. This remains true if corresponding lenses do not share an optical axis (i.e. if the two microlens arrays are shifted with respect to each other). The arrays described above are examples of generalized confocal lenslet arrays, and the light-ray-direction change in these devices is well understood [Oxburgh et al., Opt. Commun. 313, 119 (2014)]. Here we show that such micro-telescope arrays change light-ray direction like the interface between spaces with different metrics. To physicists, the concept of metrics is perhaps most familiar from General Relativity (where it is applied to spacetime, not only space, like it is here) and Transformation Optics [Pendry et al., Science 312, 1780 (2006)], where different materials are treated like spaces with different optical metrics. We illustrate the similarities between micro-telescope arrays and metric interfaces with raytracing simulations. Our results suggest the possibility of realising transformation-optics devices with micro-telescope arrays, which we investigate elsewhere

crisscrossing Science Episode 039: Nuclear Winter

In this episode, Chris Gaiser (professor of biology at Linfield College) and Mike Crosser (professor of physics at Linfield College) invite author John Coster-Mullen to discuss the technology behind the first atomic weapons that were dropped above Japan during World War II. We learn about the design differences between the bombs dropped over Hiroshima and Nagasaki and why these differences mattered. This episode references content discussed in Episode 024, which explains how nuclear power works