Best practice report – operation and maintenance requirements

Deliverable 3.6.3 from the MERiFIC Project A report prepared as part of the MERiFIC Project "Marine Energy in Far Peripheral and Island Communities"This report is a deliverable of MERiFIC Work Package 3.6: ‘Operation and Maintenance requirements’ and has been produced as a cross border collaboration between IFREMER and the University of Exeter. The report provides an overview of guidelines and recommendations for the management of O&M operations necessary for an optimal exploitation of Marine energy plants, with a focus on the specific areas of South West Cornwall, UK and Iroise sea, Brittany, France. An overview of the onshore infrastructures and ports possibly suitable for management of such O&M operations is also provided. Management of scheduled and unscheduled maintenance operations are discussed in their various aspects including site accessibility. It should be noted that this topic, including weather window assessment for operations is discussed in more details in the additional MERIFIC report D3.6.2: Best Practice for installation proceduresMERiFIC was selected under the European Cross-Border Cooperation Programme INTERREG IV A France (Channel) – England, co-funded by the ERDF

Best practice report - installation procedures

Deliverable 3.6.2 from the MERiFIC Project A report prepared as part of the MERiFIC Project "Marine Energy in Far Peripheral and Island Communities"This report is a deliverable of MERiFIC Task 3. 6: ‘Installation Procedures’ and has been produced in a cross border collaboration between IFREMER and the University of Exeter. In this report different elements are presented for the planning and organisation of installation operations for the deployment of Marine energy plants. The optimization of installation procedures are discussed and brought in a context to potential costs optimization and the availability of suitable vessels is considered. Installation procedures, which were also investigated, should include pre-installation surveys so as to optimize the design of moorings and secure laying of the power cable, a specific feature of the commissioning of such Marine energy plants. Attention should also be given to the Health and Safety procedures. Finally, the influence of the weather conditions on the success of these installation operations was discussed and studied. Especially, "Access time" and "Waiting time" weather windows were assessed for different sites in both areas of south west Cornwall and the Iroise Sea, pointing out the importance of the seasonal variability of the wave climate for the planning of installation operations.MERiFIC was selected under the European Cross-Border Cooperation Programme INTERREG IV A France (Channel) – England, co-funded by the ERDF

Estimate of the impact of background particles on the X-Ray Microcalorimeter Spectrometer on IXO

We present the results of a study on the impact of particles of galactic (GCR) and solar origin for the X-ray Microcalorimeter Spectrometer (XMS) aboard an astronomical satellite flying in an orbit at the second Lagrangian point (L2). The detailed configuration presented in this paper is the one adopted for the International X-Ray Observatory (IXO) study, however the derived estimates can be considered a conservative limit for ATHENA, that is the IXO redefined mission proposed to ESA. This work is aimed at the estimate of the residual background level expected on the focal plane detector during the mission lifetime, a crucial information in the development of any instrumental configuration that optimizes the XMS scientific performances. We used the Geant4 toolkit, a Monte Carlo based simulator, to investigate the rejection efficiency of the anticoincidence system and assess the residual background on the detector.Comment: 18 pages, 9 figure

Validity of the activPAL3 activity monitor in people moderately affected by Multiple Sclerosis

Background: Walking is the primary form of physical activity performed by people with Multiple Sclerosis (MS), therefore it is important to ensure the validity of tools employed to measure walking activity. The aim of this study was to assess the criterion validity of the activPAL3 activity monitor during overground walking in people with MS.\ud Methods: Validity of the activPAL3 accelerometer was compared to video observation in 20 people moderately affected by MS. Participants walked 20-30m twice along a straight quiet corridor at a comfortable speed.\ud Results: Inter-rater reliability of video observations was excellent (all intraclass correlations > 0.99). The mean difference (activPAL3- mean of raters) was -4.70 ± 9.09, -4.55 s ± 10.76 and 1.11 s ± 1.11 for steps taken, walking duration and upright duration respectively. These differences represented 8.7, 10.0 and 1.8% of the mean for each measure respectively. The activPAL3 tended to underestimate steps taken and walking duration in those who walked at cadences of ≤ 38 steps/minute by 60% and 47% respectively.\ud Discussion: The activPAL3 is valid for measuring walking activity in people moderately affected by MS. It is accurate for upright duration regardless of cadence. In participants with slow walking cadences, outcomes of steps taken and walking duration should be interpreted with caution

Selected Physical Properties of Jointed Goatgrass (Aegilops cylindrica Host.)

Selected physical properties of jointed goatgrass samples collected in western Nebraska and eastern Colorado were determined. Measured properties were spikelet dimensions (length 10.8 ± 0.35 mm; width 2.59 ± 0.25 mm), particle density (0.761 ± 0.016 g/m3), bulk density (351 ± 26.9 kg/m3), terminal velocity (301 ± 25.9 m/min), angle of repose (26.3 ± 0.286°), internal coefficient of friction (0.494 ± 0.007), and equilibrium moisture contents at 10% RH (6.56 ± 1.03% w.b.), 30% RH (7.43 ± 1.21% w.b.), 50% RH (9.01 ± 0.67% w.b.), 70% RH (11.89 ± 0.61% w.b.), and 90% RH (20.39 ± 2.38% w.b.). Jointed goatgrass had substantially lower particle density and bulk density values than those reported in the literature for hard red winter wheat

Selected Physical Properties of Jointed Goatgrass (Aegilops cylindrica Host.)

Selected physical properties of jointed goatgrass samples collected in western Nebraska and eastern Colorado were determined. Measured properties were spikelet dimensions (length 10.8 ± 0.35 mm; width 2.59 ± 0.25 mm), particle density (0.761 ± 0.016 g/m3), bulk density (351 ± 26.9 kg/m3), terminal velocity (301 ± 25.9 m/min), angle of repose (26.3 ± 0.286°), internal coefficient of friction (0.494 ± 0.007), and equilibrium moisture contents at 10% RH (6.56 ± 1.03% w.b.), 30% RH (7.43 ± 1.21% w.b.), 50% RH (9.01 ± 0.67% w.b.), 70% RH (11.89 ± 0.61% w.b.), and 90% RH (20.39 ± 2.38% w.b.). Jointed goatgrass had substantially lower particle density and bulk density values than those reported in the literature for hard red winter wheat

Zero Field precession and hysteretic threshold currents in spin torque oscillators with tilted polarizer

Using non-linear system theory and numerical simulations we map out the static and dynamic phase diagram in zero applied field of a spin torque oscillator with a tilted polarizer (TP-STO).We find that for sufficiently large currents, even very small tilt angles (beta>1 degree) will lead to steady free layer precession in zero field. Within a rather large range of tilt angles, 1 degree< beta <19 degree, we find coexisting static states and hysteretic switching between these using only current. In a more narrow window (1 degree<beta<5 degree) one of the static states turns into a limit cycle (precession). The coexistence of static and dynamic states in zero magnetic field is unique to the tilted polarizer and leads to large hysteresis in the upper and lower threshold currents for TP-STO operation.Comment: 5 pages, 4 figure

Dispersive magnetic excitations in the S=1 antiferromagnet Ba3_3Mn2_2O8_8

We present powder inelastic neutron scattering measurements of the S=1 dimerized antiferromagnet Ba$_3$Mn$_2$O$_8$. The $T=1.4$ K magnetic spectrum exhibits a spin-gap of $\Delta \approx 1.0$ meV and a dispersive spectrum with a bandwidth of approximately 1.5 meV. Comparison to coupled dimer models describe the dispersion and scattering intensity accurately and determine the exchange constants in Ba$_3$Mn$_2$O$_8$. The wave vector dependent scattering intensity confirms the proposed S=1 dimer bond. Temperature dependent measurements of the magnetic excitations indicate the presence of both singlet-triplet and thermally activated triplet-quintet excitations.Comment: 8 pages, 8 figures, Submitted to Physical Review B, Resubmited versio

Performance of two handheld NIR spectrometers to quantify crude protein of composite animal forage and feedstuff

Two handheld near infrared (NIR) spectrometers were used to quantify crude protein (CP) content of mixed forage and feedstuff composed of Sweet Bran, distiller’s grains, corn silage, and corn stalk. First was a transportable spectrometer, which measured in the visible and NIR ranges (320–2500 nm) with a spectral interval of 1 nm (H1). Second was a smartphone spectrometer, which measured from 900–1700 nm with a spectral interval of 4 nm (H2). Spectral data of 147 forage and feed samples were collected by both handheld instruments and split into calibration (n= 120) and validation (n= 27) sets. For H1, only absorbances in the NIR region (780–2500 nm) were used in the multivariate analyses, while for H2, absorbances in the second and third overtone regions (940–1660 nm) were used. Principal component analysis (PCA) and partial least squares (PLS) regression models were developed using mean-centered data that had been preprocessed using standard normal variate (SNV) or Savitzky-Golay first derivative (SG1) or second derivative (SG2) algorithm. PCA models showed two major groups—one with Sweet Bran and distillers grains, and the other with corn silage and corn stalk. Using H1 spectra, the PLS regression model that best predicted CP followed SG1 preprocessing. This model had low root mean square error of prediction (RMSEP= 2.22%) and high ratio of prediction to deviation (RPD= 5.24). With H2 spectra, the model best predicting CP was based on SG2 preprocessing, returning RMSEP= 2.05% and RPD= 5.74. These values were not practically different than those of H1, indicating similar performance of the two devices despite having absorbance measurements only in the second and third overtone regions with H2. The result of this study showed that both handheld NIR instruments can accurately measure forage and feed CP during screening, quality, and process control applications