Investigation of pre and post plating surface roughness of electroless nickel phosphorus coated substrate for diamond turning application

In an overarching project to reduce the number of defects found in electroless nickel phosphorus alloy (EN-P) coatings on large diamond-turned components used in the next generation of reel-to-reel (R2R) printing stations, the significance of the coating surface on achieving a wear resistant and optically smooth surface has been investigated. This paper presents an investigation that focuses on the substrate roughness variation achieved through different pre-treatment methods prior to coating using a commercial plating solution. It looks at the number of features observed pre and post plating. The results provide some suggestions with respect to the diamond machining of a 100 micron thick EN-P coating

Low-profile and wearable energy harvester based on plucked piezoelectric cantilevers

The Pizzicato Energy Harvester (EH) introduced the technique of frequency up-conversion to piezoelectric EHs wearable on the lateral side of the knee-joint. The operation principle is to pluck the piezoelectric bimorphs with plectra so that they produce electrical energy during the ensuing mechanical vibrations. The device presented in this work is, in some ways, an evolution of the earlier Pizzicato: it is a significantly more compact and lighter device; the central hub holds 16 piezoelectric bimorphs shaped as trapezoids, which permits a sleek design and potentially increased energy output for the same bimorph area. Plectra were formed by Photochemical Machining of a 100-μm-thick steel sheet. To avoid the risk of short-circuiting, the plectra were electrically passivated by sputtering a 100 nm layer of ZrO2. Bench tests with the steel plectra showed a very large energy generation. Polyimide plectra were also manufactured with a cutting plotter from a 125μm-thick film. Besides bench tests, a volunteer wore the device while walking on flat ground or climbing stairs, with a measured energy output of approximately 0.8 mJ per step. Whereas most of the tests were performed by the traditional method of discharging the rectified output from the EH onto a resistive load, tests were performed also with a circuit offering a stabilised 3.3 V supply. The circuit produced a stable 0.1 mA supply during running gait with kapton plectra

Predicting the effects of sand erosion on collector surfaces in CSP plants

This paper presents a methodology to predict the optical performance and physical topography of the glass collector surfaces of any given CSP plant in the presence of sand and dust storms, providing that local climate conditions are known and representative sand and dust particles samples are available. Using existing meteorological data for a defined CSP plant in Egypt, plus sand and dust samples from two desert locations in Libya, we describe how to derive air speed, duration, and sand concentrations to use within the Global CSP Laboratory sand erosion simulation rig at Cranfield University. This then allows us to predict the optical performance of parabolic trough collector glass after an extended period by the use of accelerated ageing. However the behavior of particles in sandstorms is complex and has prompted a theoretical analysis of sand particle dynamics which is also described in this paper

A 'slow' manifesto for comparative research on work and employment

This paper addresses cross-national comparative research in employment relations and related fields. Its purpose is to argue the case for research which makes a long-term, in-depth engagement with the local and national social contexts under study, in order to gain deeper and more reliable insights into the nature of, and reasons for, cross-national similarities and differences. We call this form of engagement “slow comparativism”. We aim to establish a number of basic precepts of ‘slow comparativism’ as a practical methodological approach. In presenting these, we will raise a number of questions which we think are important to all attempts at in-depth comparison, and which, we argue, need to be considered at all stages of the research process (research design, execution, and the presentation of findings). These questions include: (i) challenges in accessing the local ‘common sense’ of actors, through research processes which should be seen as much more encompassing than what happens in formal research processes such as interviews; (ii) challenges, both literal and figurative, of acquiring local ‘languages’; (iii) challenges of avoiding ethnocentrism through creating and maintaining a critical distance from the assumptions of research subjects through part-alienation and ensuring reflexivity; (iv) challenges of comparability between fieldwork conducted in different countries, and the need to think of comparative research as constituting ‘federal’ projects, thinking of fieldwork in different countries as constituting linked, but to some extent separate projects. Our analysis is developed through an examination of comparative literature in industrial relations, as well as through reflection on the challenges the two authors have faced in executing in-depth comparative research on labour management, industrial relations, and trade union organisation. Our presentation of these challenges, and the difficulties that comparative scholars of work and employment face in resolving them, can, we hope, be used to provoke a discussion among those conducting comparative research on work and employment about how truth claims are generated in general. We also seek to provide a basis by which those conducting slower forms of comparativism, through what we term ‘implicit ethnographies’, can find better ways of developing and defending their modes of research within a broader academic political economy which is not always favourable to such approaches

Contact cleaning of polymer film solar reflectors

This paper describes the accelerated ageing of polymer film reflecting surfaces under the conditions to be found during contact cleaning of Concentrating Solar Power (CSP) collectors in the presence of dust and sand particles. In these situations, contact cleaning using brushes and water is required to clean the reflecting surfaces. Whilst suitable for glass reflectors, this paper discusses the effects of existing cleaning processes on the optical and visual properties of polymer film surfaces, and then describes the development of a more benign but effective contact cleaning process for cleaning polymer reflectors. The effects of a range of cleaning brushes are discussed, with and without the presence of water, in the presence of sand and dust particles from selected representative locations. Reflectance measurements and visual inspection shows that a soft cleaning brush with a small amount of water can clean polymer film reflecting surfaces without inflicting surface damage or reducing specular reflectance

Airborne sand and dust soiling of solar collecting mirrors

The reflectance of solar collecting mirrors can be significantly reduced by sand and dust soiling, particularly in arid environments. Larger airborne sand and dust particles can also cause damage by erosion, again reducing reflectance. This work describes investigations of the airborne particle size, shape, and composition in three arid locations that are considered suitable for CSP plants, namely in Iran, Libya, and Algeria. Sand and dust has been collected at heights between 0.5 to 2.0m by a variety of techniques, but are shown not to be representative of the particle size found either in ground dust and sand, or on the solar collecting mirror facets themselves. The possible reasons for this are proposed, most notably that larger particles may rebound from the mirror surface. The implications for mirror cleaning and collector facet erosion are discusse

Structure zone diagram and particle incorporation of nickel brush plated composite coatings

This work studies the deposition of aluminium-incorporated nickel coatings by brush electroplating, focusing on the electroplating setup and processing parameters. The setup was optimised in order to increase the volume of particle incorporation. The optimised design focused on increasing the plating solution flow to avoid sedimentation, and as a result the particle transport experienced a three-fold increase when compared with the traditional setup. The influence of bath load, current density and the brush material used was investigated. Both current density and brush material have a significant impact on the morphology and composition of the coatings. Higher current densities and non-abrasive brushes produce rough, particle-rich samples. Different combinations of these two parameters influence the surface characteristics differently, as illustrated in a Structure Zone Diagram. Finally, surfaces featuring crevices and peaks incorporate between 3.5 and 20 times more particles than smoother coatings. The presence of such features has been quantified using average surface roughness Ra and Abbott-Firestone curves. The combination of optimised setup and rough surface increased the particle content of the composite to 28 at.%

The design of dust barriers to reduce collector mirror soiling in CSP plants

In this work we investigate, design, and evaluate a number of dust barrier designs that would be appropriate to reduce soiling of glass mirror solar collectors in the solar field of an existing CSP plant. The principal objective was to reduce the amount of soiling (and hence the amount of cleaning water consumed) by 50% in comparison with current cleaning procedures (considering particles of size >25 µm). “Fluent” CFD software was used to model of a range of potential dust barrier shapes, sizes, and porosities. Airflows and wind loadings were analyzed in this way. A number of potential designs were then taken forward for experimental validation. Initial validation involved wind tunnel evaluation of a small number of potential designs, using a new wind tunnel specifically designed and built for this project. Larger-scale outdoor validation was carried out both at Cranfield University in the UK and at CIEMAT-PSA (Plataforma Solar de Almeria) in Spain. Initial results were independent of location and barrier shape and showed that the percentage of particles that were stopped completely or travelled less than 1m beyond the barrier was in the range 45.8 ± 5%

The design and modification of a parabolic trough system for the hydrothermal liquefaction of waste

We describe the design of a small-scale parabolic trough with a high-pressure absorber bundle to convert microalgae into bio-oil. The “proof-of-concept” system uses an existing Global CSP solar captor, with its reflectance enhanced by the addition of Skyfuel® ReflecTech Plus polymer film and has its original receiver tube replaced by a novel high-pressure multi-tube absorber and reactor. Initial results obtained at Kota University in Rajasthan, India demonstrated that temperatures up to 320°C are possible, and a bio-oil, similar to palm oil, was extracted from the reactor

Fish Oil Blunts Lung Function Decrements Induced by Acute Exposure to Ozone in Young Healthy Adults: A Randomized Trial

Background: Over one-third of the U.S. population is exposed to unsafe levels of ozone (O3). Dietary supplementation with fish oil (FO) or olive oil (OO) has shown protection against other air pollutants. This study evaluates potential cardiopulmonary benefits of FO or OO supplementation against acute O3 exposure in young healthy adults. Methods: Forty-three participants (26 ± 4 years old; 47% female) were randomized to receive 3 g/day of FO, 3 g/ day OO, or no supplementation (CTL) for 4 weeks prior to undergoing 2-hour exposures to filtered air and 300 ppb O3 with intermittent exercise on two consecutive days. Outcome measurements included spirometry, sputum neutrophil percentage, blood markers of inflammation, tissue injury and coagulation, vascular function, and heart rate variability. The effects of dietary supplementation and O3 on these outcomes were evaluated with linear mixed-effect models. Results: Compared with filtered air, O3 exposure decreased FVC, FEV1, and FEV1/FVC immediately post exposure regardless of supplementation status. Relative to that in the CTL group, the lung function response to O3 exposure in the FO group was blunted, as evidenced by O3-induced decreases in FEV1 (Normalized CTL − 0.40 ± 0.34 L, Normalized FO − 0.21 ± 0.27 L) and FEV1/FVC (Normalized CTL − 4.67 ± 5.0 %, Normalized FO − 1.4 ± 3.18 %) values that were on average 48% and 70% smaller, respectively. Inflammatory responses measured in the sputum immediately post O3 exposure were not different among the three supplementation groups. Systolic blood pressure elevations 20-h post O3 exposure were blunted by OO supplementation. Conclusion: FO supplementation appears to offer protective effects against lung function decrements caused by acute O3 exposure in healthy adults