348 research outputs found
All-optical busbar differential protection scheme for electric power systems
This paper proposes a novel implementation of a differential protection scheme using magneto-optic current sensors. The proposed all-Optical Differential Protection (ODP) scheme utilizes inherent properties of magneto-optic sensors connected in series to perform differential protection functionality. In order to demonstrate the validity of the proposed scheme, all constituent components such as optical fibre, polarisers and Faraday rotators have been modelled using the Jones matrix representation. Through selected simulation-based case studies, including external and internal (high resistive and solid) faults, the paper demonstrates that the proposed novel ODP scheme for busbar protection meets the protection relaying performance criteria in terms of discrimination, sensitivity, stability, as well as ultra-high speed of operation
Fatigue stress resistance of some composite materials for dental fillings
The paper investigates fatigue stress resistance of some originally made composite materials based on Bis-GMA resin with fluoridated glass and YbF3. The material was used to fill in the cavities in teeth extracted for orthodontic reasons. For laboratory tests a mastication simulator was used. The tooth samples were placed in special holders with resin and exposed to cyclic mechanical loads (100 000 cycles) in order to assess their resistance to fatigue stress. The influence of repeatable mechanical loads on the teeth and the structure of the material were investigated. Additionally, the impact of cyclic loads on fluoride release from the composite materials was estimate
Measurement of disruption forces in JET using fiber-optic sensors
Monitoring the forces induced on the vacuum vessel when a disruption occurs is essential for the protection of the machine. Since divertor coils have been installed in JET, during disruptions a significant difference between the forces measured on the top and the bottom of the machine has been observed. In order to investigate these further, optical fiber transducers FBGs (Fiber Bragg Gratings) were installed in addition to the currently used strain gauges. During VDE (Vertical Displacement Event) tests, these new transducers were used to measure different level of disruptions ranging from 80T up to 230T vertical forces. The results were then compared with the strain gauges. The FBG measurement was carried out using a broadband light source illuminating an array of 4 FBGs through a combination of directional couplers, connectors and fiber-optic cable. The forces measured both by FBG and by the strain gauges are within the same range, except for the initial swing where large random differences are observed. The tests have demonstrated that the FBG-based force measurement system has adequate resolution (±1.52strain corresponding to a force of 4kN due to the geometry of the leg) and measurement range (50002strain or 13000kN) for this application
Angular distributions in Monte Carlo event generation of weak single-pion production
One of the substantial sources of systematic errors in neutrino oscillation
experiments that utilize neutrinos from accelerator sources stems from a lack
of precision in modeling single-pion production (SPP). Oscillation analyses
rely on Monte Carlo event generators (MC), providing theoretical predictions of
neutrino interactions on nuclear targets. Pions produced in these processes
provide a significant fraction of oscillation signal and background on both
elementary scattering and detector simulation levels. Thus, it is of critical
importance to develop techniques that will allow us to accommodate
state-of-the-art theoretical models describing SPP into MCs.
In this work, we investigate various algorithms to implement single-pion
production models in Monte Carlo event generators. Based on comparison studies,
we propose a novel implementation strategy that combines satisfactory
efficiency with high precision in reproducing details of theoretical models
predictions, including pion angular distributions. The proposed implementation
is model-independent, thereby providing a framework that can include any model
for SPP. We have tested the new algorithm with the Ghent Low Energy Model for
single-pion production implemented in the NuWro Monte Carlo event generator.Comment: 13 pages, 8 figure
Can existing drugs approved for other indications retard renal function decline in patients with type 1 diabetes and nephropathy?
Mounting evidence from human, animal, and in vitro studies indicates that existing drugs, developed to treat other disorders, also might be effective in preventing or slowing the progression of diabetic nephropathy to end-stage renal disease. Examples of such drugs include the urate-lowering agent allopurinol, the anti-tumor necrosis factor agents etanercept and infliximab, and the immunomodulating drug abatacept. Because some of these medications are already on the market and have been used for a number of years for other indications, they can be tested immediately in human beings for a beneficial effect on renal function in diabetes. Special emphasis should be placed on evaluating the use of these drugs early in the course of diabetic nephropathy when renal damage is most likely to be reversible and interventions can yield the greatest delay to end-stage renal disease
Early progressive renal decline precedes the onset of microalbuminuria and its progression to macroalbuminuria
OBJECTIVE
Progressive decrease in the glomerular filtration rate (GFR), or renal decline, in
type 1 diabetes (T1D) is observed in patients with macroalbuminuria. However,
it is unknown whether this decline begins during microalbuminuria (MA) or
normoalbuminuria (NA).
RESEARCH DESIGN AND METHODS
The study group (second Joslin Kidney Study) comprises patients with T1D and NA
(n = 286) or MA (n = 248) who were followed for 4-10 years (median 8 years). Serial
measurements (median 6, range 3–16) of serum creatinine and cystatin C were
used jointly to estimate GFR (eGFRcr-cys) and assess its trajectories during
follow-up.
RESULTS
Renal decline (progressive eGFRcr-cys loss of at least 3.3% per year) occurred in
10% of the NA and 35% of the MA (P , 0.001). In both groups, the strongest
determinants of renal decline were baseline serum concentrations of uric acid
(P , 0.001) and tumor necrosis factor receptor 1 or 2 (TNFR-1 or -2, P , 0.001).
Other significant risk factors included baseline HbA1c, age/diabetes duration, and
systolic blood pressure. Relative impacts of these determinants were similar in NA
and MA. Renal decline was not associated with sex or baseline serum concentration of TNF-a, IL-6, IL-8, IP-10, MCP-1, VCAM, ICAM, Fas, or FasL.
CONCLUSIONS
Renal decline in T1D begins during NA and it is determined by multiple factors,
similar to MA. Thus, this early decline is the primary disease process leading to
impaired renal function in T1D. Changes in albumin excretion rate, such as the
onset of MA or its progression to macroalbuminuria, are either caused by or develop in parallel to the early renal declin
Magnetic flux jumps in textured Bi2Sr2CaCu2O(8+d)
Magnetic flux jumps in textured Bi2Sr2CaCu2O(8+d) have been studied by means
of magnetization measurements in the temperature range between 1.95 K and Tc,
in an external magnetic field up to 9 T. Flux jumps were found in the
temperature range 1.95 K - 6 K, with the external magnetic field parallel to
the c axis of the investigated sample. The effect of sample history on magnetic
flux jumping was studied and it was found to be well accounted for by the
available theoretical models. The magnetic field sweep rate strongly influences
the flux jumping and this effect was interpreted in terms of the influence of
both flux creep and the thermal environment of the sample. Strong flux creep
was found in the temperature and magnetic field range where flux jumps occur
suggesting a relationship between the two. The heat exchange conditions between
the sample and the experimental environment also influence the flux jumping
behavior. Both these effects stabilize the sample against flux instabilities,
and this stabilizing effect increases with decreasing magnetic field sweep
rate. Demagnetizing effects are also shown to have a significant influence on
flux jumping.Comment: 10 pages, 6 figures, RevTeX4, submitted to Phys. Rev.
Constraints in modeling the quasielastic response in inclusive lepton-nucleus scattering
We show that the quasielastic (QE) response calculated with the superscaling approach (SuSAv2) model, that relies on the scaling phenomenon observed in the analysis of (e,e′) data and on the relativistic mean-field theory, is very similar to that from a relativistic distorted-wave impulse approximation model when only the real part of the optical potentials is employed. The coincidence between the results from these two completely independent approaches, which satisfactorily agree with the inclusive data, reinforces the reliability of the quasielastic predictions stemming from both models and sets constraints for the QE response. We also study the low-energy and momentum-transfer region of the inclusive response by confronting the results of the relativistic mean-field model with those of the Hartree-Fock continuum random-phase approximation model, which accounts for nuclear long-range correlations. Finally, we present a comparison of our results with the recent Jefferson Laboratory (JLab) (e,e′) data for argon, titanium, and carbon, finding good agreement with the three data sets.Spanish Ministerio de Economia y Competitividad and European Regional Development Fund) FIS2017-88410-PJunta de Andalucia FQM 160, SOMM17/6105/UGRConsolider-Ingenio 2000 program CPAN (CSD2007-0042)Spanish Government (FPA2015-65035P and RTI2018-098868-B-I00
Advanced fault location in MTDC networks utilising optically-multiplexed current measurements and machine learning approach
This paper presents a method for accurate fault localisation of DC-side faults in Voltage Source Converter (VSC) based Multi-Terminal Direct Current (MTDC) networks utilising optically-multiplexed DC current measurements sampled at 5 kHz, off-line continuous wavelet transform and machine learning approach. The technical feasibility of optically-based DC current measurements is evaluated through laboratory experiments using commercially available equipment. Simulation-based analysis through Matlab/Simulink® has been adopted to test the proposed fault location algorithm under different fault types and locations along a DC grid. Results revealed that the proposed fault location scheme can accurately calculate the location of a fault and successfully identify its type. The scheme has been also found to be effective for highly resistive fault with resistances of up to 500 Ω. Further sensitivity analysis revealed that the proposed scheme is relatively robust to additive noise and synchronisation errors
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