The Effectiveness Of Repairing Fatigue Damaged 7050 Aluminium Alloy Using Shot Peening

Shot peening is an effective life extension surface treatment process. In this study, experiments were performed to investigate whether shot peening could be used to recover the fatigue resistance of aluminium alloy 7050 that has experienced prior fatigue damage. The results showed that shot peening may be used for restoring the original fatigue life of the material, but the effectiveness strongly depends on the amount of prior damage (e.g. the crack depth of any cracks that have already formed) in the material. A numerical model was established and the effect of residual stress was incorporated into the model. The prediction by the model agreed well with the experimental results in terms of trend

Optically trapped atom interferometry using the clock transition of large Rb-87 Bose-Einstein condensates

We present a Ramsey-type atom interferometer operating with an optically trapped sample of 10^6 Bose-condensed Rb-87 atoms. The optical trap allows us to couple the |F =1, mF =0>\rightarrow |F =2, mF =0> clock states using a single photon 6.8GHz microwave transition, while state selective readout is achieved with absorption imaging. Interference fringes with contrast approaching 100% are observed for short evolution times. We analyse the process of absorption imaging and show that it is possible to observe atom number variance directly, with a signal-to-noise ratio ten times better than the atomic projection noise limit on 10^6 condensate atoms. We discuss the technical and fundamental noise sources that limit our current system, and outline the improvements that can be made. Our results indicate that, with further experimental refinements, it will be possible to produce and measure the output of a sub-shot-noise limited, large atom number BEC-based interferometer. In an addendum to the original paper, we attribute our inability to observe quantum projection noise to the stability of our microwave oscillator and background magnetic field. Numerical simulations of the Gross-Pitaevskii equations for our system show that dephasing due to spatial dynamics driven by interparticle interactions account for much of the observed decay in fringe visibility at long interrogation times. The simulations show good agreement with the experimental data when additional technical decoherence is accounted for, and suggest that the clock states are indeed immiscible. With smaller samples of 5 \times 10^4 atoms, we observe a coherence time of {\tau} = (1.0+0.5-0.3) s.Comment: 22 pages, 6 figures Addendum: 11 pages, 6 figure

Photonic qubits, qutrits and ququads accurately prepared and delivered on demand

Reliable encoding of information in quantum systems is crucial to all approaches to quantum information processing or communication. This applies in particular to photons used in linear optics quantum computing (LOQC), which is scalable provided a deterministic single-photon emission and preparation is available. Here, we show that narrowband photons deterministically emitted from an atom-cavity system fulfill these requirements. Within their 500 ns coherence time, we demonstrate a subdivision into d time bins of various amplitudes and phases, which we use for encoding arbitrary qu-d-its. The latter is done deterministically with a fidelity >95% for qubits, verified using a newly developed time-resolved quantum-homodyne method.Comment: 5 pages, 4 figure

Precision atomic gravimeter based on Bragg diffraction

We present a precision gravimeter based on coherent Bragg diffraction of freely falling cold atoms. Traditionally, atomic gravimeters have used stimulated Raman transitions to separate clouds in momentum space by driving transitions between two internal atomic states. Bragg interferometers utilize only a single internal state, and can therefore be less susceptible to environmental perturbations. Here we show that atoms extracted from a magneto-optical trap using an accelerating optical lattice are a suitable source for a Bragg atom interferometer, allowing efficient beamsplitting and subsequent separation of momentum states for detection. Despite the inherently multi-state nature of atom diffraction, we are able to build a Mach-Zehnder interferometer using Bragg scattering which achieves a sensitivity to the gravitational acceleration of $\Delta g/g = 2.7\times10^{-9}$ with an integration time of 1000s. The device can also be converted to a gravity gradiometer by a simple modification of the light pulse sequence.Comment: 13 pages, 11 figure

Spallation-Like Phenomenon Induced By Laser Shock Peening Surface Treatment On 7050 Aluminum Alloy

Laser shock peening (LSP) is a promising surface treatment for fatigue life extension of metallic materials. The benefits include deeper residual stresses (>1 mm) and a smoother surface finish than conventional glass bead peening. However, fatigue tests on 7050 aluminium alloy specimens have shown that LSP may cause a reduction in life due to internal cracking generated during the process. A series of tests were carried out to identify any technological risks such as internal cracking associated with the use of LSP. Numerical modelling was also carried out and the results of this numerical prediction agreed well with the experimental results

Ion cyclotron resonant heating 2 x 170/sup 0/ loop antenna for the Tandem Mirror Experiment-Upgrade

This paper reviews the mechanical design and improvements that have taken place on the loop type ion cyclotron resonance heating (ICRH) antennas that are located in the center cell region of the Tandem Mirror Experiment-Upgrade (TMX-U)

Literature review on the use of action research in higher education

This literature review considers the use of action research in higher education. It specifically looks at two areas of higher education activity. The first concerns academic teaching practice and includes a discussion of research and pedagogy practice, and staff development. The second considers student engagement. In both these core features of higher education, action research has proved to be a central approach to the investigation, reflection and improvement of practice. Each of these main foci includes a discussion of the limitations of the literature. The review illustrates the extent and range of uses to have benefited from an action research approach

The joint effects of apolipoprotein B, apolipoprotein A1, LDL cholesterol, and HDL cholesterol on risk: 3510 cases of acute myocardial infarction and 9805 controls†

AIMS: Plasma levels of apolipoprotein B (apoB), the main surface protein on LDL particles, and LDL-C, the amount of cholesterol in those particles, are closely correlated and, considered separately, are positive risk factors. Plasma levels of apolipoprotein A(1), the main surface protein on HDL particles, and HDL-C, the amount of cholesterol in those particles, are also closely correlated with each other and, considered separately, are negative risk factors. The interdependence of these four risk factors is unclear. METHODS AND RESULTS: Case-control study among 3510 acute myocardial infarction patients (without prior vascular disease, diabetes, or statin use) in UK hospitals and 9805 controls. Relative risks (age, sex, smoking, and obesity-adjusted) were more strongly related to apoB than to LDL-C and, given apoB, more strongly negatively related to apoA(1) than to HDL-C. The ratio apoB/apoA(1) was uncorrelated with time since symptom onset in cases, was reproducible in samples collected a few years apart in controls (correlation 0.81), and encapsulated almost all the predictive power of these four measurements. Its effect was continuous, substantial throughout the UK normal range [relative risk, top vs. bottom decile of this ratio, 7.3 (95% CI 5.8-9.2)] and varied little with age. The ratio apoB/apoA(1) was substantially more informative about risk (chi(1)(2) = 550) than were commonly used measures such as LDL-C/HDL-C, total/HDL cholesterol, non-HDL cholesterol, and total cholesterol (chi(1)(2) = 407, 334, 204, and 105, respectively). Given apoB and apoA(1), the relationship with risk of LDL-C was reversed, and this reversal was strengthened by appropriate allowance for random measurement errors in two correlated variables. Given usual apoB, lower LDL-C (consistent with smaller LDL particles) was associated with higher risk (P < 0.0001). During the first 8 h after symptom onset HDL-C increased by about 10%, precluding reliable assessment of the joint relationship of apoA(1) and pre-onset HDL-C with risk in such retrospective case-control studies. CONCLUSION: Apolipoprotein ratios are more informative about risk than lipid fractions are. This suggests that, among lipoprotein particles of a particular type (LDL or HDL), some smaller and larger subtypes differ in their effects on risk. Direct measurements of even more specific subtypes of lipoprotein particles may be even more informative about risk

The Change Up Project : using social norming theory with young people to address domestic abuse and promote healthy relationships

This paper presents the findings of a secondary analysis of data collected during a pilot project, Change Up, which used a social norming approach (SNA) to address domestic violence and abuse (DVA) with young people aged 13–14. A SNA is based upon a well-articulated theory of behavior and evidence-based methodology for addressing social justice issues. This reflects a paradigm shift focusing upon strengths and positives, rather than pathologizing behaviours. Adopting a SNA, the Change Up project comprised a baseline survey followed by the intervention (workshop and peer-to-peer campaign), ending with a post-intervention survey. It was delivered in two high schools in a UK city between 2015 and 16. A secondary analysis of the survey data collected during the surveys and qualitative data collected at the end of each workshop was undertaken and this is reported here. Change Up data illustrates that most young people in the sample thought that DVA is unacceptable. There was, however, a gender difference in the norms held about the social acceptability of girls using physical violence against boys (and vice versa). The analysis of Change Up data indicates that a social norming approach to DVA programs aimed at young people can be successful in promoting attitude and behaviour change. It also highlights a continuing need for young people’s education about relationships and gender equality