Online calibration of high-frequency partial discharge signals in three-phase belted power cables

Partial discharge (PD) magnitudes from classical detection techniques are expressed in terms of apparent charges. Signals from HF/VHF/UHF techniques on substation components are often hard to express in this quantity because of complex signal excitation and propagation channels. A method to calibrate PD signals obtained during online inductive detection in medium voltage belted cables is described. online inductive detection implies that the impedances of components present in substations essentially determine the detected PD signal magnitude. The use of belted cables means, that the coupling of a PD event to the conductors not only depends on the PD site within the cross-section of the cable or cable accessory, but also becomes dependent on the momentary phase angle. In addition, during signal propagation the signal magnitude may alter according to the propagation modes of a multi-conductor cable. These aspects are studied quantitatively by the use of theoretical modelling in addition to offline and online experiments. PD diagnostic equipment including pulse injection capability allows online calibration with sufficient accuracy, irrespective of the actual substation arrangement

Assessing the use of private sector techniques and strategies in the public sector: the case of the department of provincial treasury & planning, Eastern Cape Province

The aim of this study was to determine and investigate the extent to which the Department of Treasury and Planning manage public finance making use of relevant private sector techniques and strategies. Financial management is a critical element of good governance and it requires a great deal of attention with parallel internal systems and controls. The study determines the role of various bodies within the public finance environment and the relevant legislative frameworks towards efficient and effective financial management by departments. The Public Finance Management Act(1999) and National Treasury Regulations (2009) require all government departments to ensure accountability on resource allocated to be able to measure value for money in relation to the delivery services to communities. The primary objective of this study was to assess the effectiveness and efficient management of public finance in terms of the PFMA as the legislative framework and the MTEF as a financial management tool. The Constitution Republic of South Africa (Act 108 of 1996) makes a provision that all the three government spheres to be developmental-oriented in nature with clear accountability and transparency lines towards service delivery. On the same breath, The Public Finance Management Act of 1999 (PFMA) is meant “To regulate financial management in the national government and provincial governments; to ensure that all revenue, expenditure, assets and liabilities of those governments are managed efficiently and effectively; to provide for the responsibilities of persons entrusted with financial management in those governments; and to provide for matters connected therewith”. With the above introductory contentions from different authors and researchers, this study will basically be on providing more details on the policy documents namely; PFMA so to establish the nature and extent to which effective and efficient financial management has improved good governance in the Department of Treasury & Planning, Eastern Cape Province

Coherent States for infinite homogeneous waveguide arrays

Perelomov coherent states for equally spaced, infinite homogeneous waveguide arrays with Euclidean E(2) symmetry are defined, and new resolutions of the identity are constructed in Cartesian and polar coordinates. The key point to construct these resolutions of the identity is the fact that coherent states satisfy Helmholtz equation (in coherent states labels) an thus a non-local scalar product with a convolution kernel can be introduced which is invariant under the Euclidean group. It is also shown that these coherent states for the Eucliean E(2) group have a simple and natural physical realization in these waveguide arrays.Spanish MICINN through the project PGC2018-097831-B-I00 and Junta de Andalucı́a through the project FEDER/UJA-1381026

Matrix-dependent size modifications of iron oxide nanoparticles (Ferumoxytol) spiked into rat blood cells and plasma : Characterisation with TEM, AF4-UV-MALS-ICP-MS/MS and spICP-MS

KN gratefully acknowledges the University of Aberdeen for an Elphinstone Ph.D. studentship and the Niger Delta Development Commission (NDDC) for a research grant (RG-13451-10). The authors also gratefully acknowledge Postnova Analytics UK especially Dr. Bassem Sabagh for the loan of the AF4 system together with training, support, and advice on the technique. Microscopy was performed at the Microscopy and Histology Core facility, University of Aberdeen.Peer reviewedPostprin

Sea level measurement using single GNSS antenna SNR signals

This thesis presents a possible method to calculate sea level variation using geodetic-quality Global Navigate Satellite System (GNSS) receivers. Three antennas are used: two small antennas and a choke ring one, analyzing only Global Positioning System signals. The main goal of the thesis is to test a modified configuration for antenna set up. In particular, measurements obtained tilting one antenna to face the horizon are compared to measurements obtained from antennas looking upward. The location of the experiment is a coastal environment nearby the Onsala Space Observatory in Sweden. Sea level variations are obtained using periodogram analysis of the SNR signal and compared to synthetic gauge generated from two independent tide gauges. The choke ring antenna provides poor result, with an RMS around 6 cm and a correlation coefficients of 0.89. The smaller antennas provide correlation coefficients around 0.93. The antenna pointing upward present an RMS of 4.3 cm and the one pointing the horizon an RMS of 6.7 cm. Notable variation in the statistical parameters is found when modifying the length of the interval analyzed. In particular, doubts are risen on the reliability of certain scattered data. No relation is found between the accuracy of the method and weather conditions. Possible methods to enhance the available data are investigated, and correlation coefficient above 0.97 can be obtained with small antennas when sacrificing data points. Hence, the results provide evidence of the suitability of SNR signal analysis for sea level variation in coastal environment even in the case of adverse weather conditions. In particular, tilted configurations provides comparable result with upward looking geodetic antennas. A SNR signal simulator is also tested to investigate its performance and usability. Various configuration are analyzed in combination with the periodogram procedure used to calculate the height of reflectors. Consistency between the data calculated and those received is found, and the overall accuracy of the height calculation program is found to be around 5 mm for input height below 5 m. The procedure is thus found to be suitable to analyze the data provided by the GNSS antennas at Onsala

Upper extremity kinematics: Development of a quantitative measure of impairment severity and dissimilarity after stroke

Strokes are a leading cause of disability, with many experiencing difficulty in recovering arm movement, particularly hand function and grasping ability. There is currently no objective measure of movement quality, and without it, rehabilitative interventions remain at best estimations of the underlying neural structures response to produce movement. In this paper, we utilize a novel modification to Procrustean distance to quantify curve dissimilarity and propose the Reach Severity and Dissimilarity Index (RSDI) as an objective measure of motor deficits. All experiments took place at the Medstar National Rehabilitation Hospital; persons with stroke were recruited from the hospital patient population. Using Fugl-Meyer (FM) scores and reach capacities, stroke survivors were placed in mild or severe impairment groups. Individuals completed sets of reach-to-target tasks to extrapolate kinematic metrics describing motor performance. The Procrustes method of statistical shape analysis was modified to identify reaching sub-movements that were congruous to able-bodied sub-movements. Movement initiation proceeds comparably to the reference curve in two- and three-dimensional representations of mild impairment movement. There were significant effects of the location of congruent segments between subject and reference curves, mean velocities, peak roll angle, and target error. These metrics were used to calculate a preliminary RSDI score with severity and dissimilarity sub-scores, and subjects were reclassified in terms of rehabilitation goals as Speed Emphasis, Strength Emphasis, and Combined Emphasis. The Modified Procrustes method shows promise in identifying disruptions in movement and monitoring recovery without adding to patient burden. The proposed RSDI score, while limited in scope, can be adapted and expanded to other functional movements and used as an objective clinical tool

MONITORING OF FLUIDIZATION QUALITY, DRYING AND SPRAY STABILITY IN A FLUIDIZED BED

Experimental studies were conducted for monitoring fluidization quality, drying and nozzle spray stability in gas - solid fluidized beds of powders. The research focused on the development of triboelectric, acoustic emission and vibration monitoring methods as these can be reliably applied to a wide range of operating conditions at low cost and also often non - intrusively. In a small scale vibrated fluidized bed of powder, it was found that the minimum bubbling velocity and minimum fluidization velocity decreased with increasing vibration. This was because vibration aided in the breakup of inter-particle cohesive forces. Vibration also accelerated the drying of wet, fine and cohesive particles by breaking up wet agglomerates. Triboelectric probes were successfully used to monitor this drying and to determine the effect of vibration on the drying. Liquid injection into gas-solid fluidized beds has an adverse effect on bed fluidity. Acoustic and vibration measurements were extensively analyzed and correlated to bed fluidity through avalanche testing to successfully detect the bed fluidity of a large scale gas-solid fluidized bed. In addition, the acoustic and vibration measurements provided an indication of the time required to mix the solids after liquid injection into the bed. Spray stability is a critical factor when injecting liquid into gas-solid fluidized beds. The signals from an accelerometer placed on the conduit leading up to industrial nozzles were correlated to the spray stability in open air. However, when the nozzles were inserted into a large scale gas-solid fluidized bed the accelerometer signals were different. The mounting in the bed kept the nozzle assembly more stable, affecting the amplitude of the measured signal fluctuations but the effects of fluidization prevented direct calibration of spray stability in the bed to open air results. The accelerometer could still be used to evaluate the relative stability in the bed. In addition the accelerometer allowed the effects of gas properties and gas to liquid ratio on spray stability to be investigated

Nanoresolution real-time 3D orbital tracking for studying mitochondrial trafficking in vertebrate axons in vivo

We present the development and in vivo application of a feedback-based tracking microscope to follow individual mitochondria in sensory neurons of zebrafish larvae with nanometer precision and millisecond temporal resolution. By combining various technical improvements, we tracked individual mitochondria with unprecedented spatiotemporal resolution over distances of >100 mu m. Using these nanoscopic trajectory data, we discriminated five motional states: a fast and a slow directional motion state in both the anterograde and retrograde directions and a stationary state. The transition pattern revealed that, after a pause, mitochondria predominantly persist in the original direction of travel, while transient changes of direction often exhibited longer pauses. Moreover, mitochondria in the vicinity of a second, stationary mitochondria displayed an increased probability to pause. The capability of following and optically manipulating a single organelle with high spatiotemporal resolution in a living organism offers a new approach to elucidating their function in its complete physiological context

Nonlinear and Quantum Optics with Whispering Gallery Resonators

Optical Whispering Gallery Modes (WGMs) derive their name from a famous acoustic phenomenon of guiding a wave by a curved boundary observed nearly a century ago. This phenomenon has a rather general nature, equally applicable to sound and all other waves. It enables resonators of unique properties attractive both in science and engineering. Very high quality factors of optical WGM resonators persisting in a wide wavelength range spanning from radio frequencies to ultraviolet light, their small mode volume, and tunable in- and out- coupling make them exceptionally efficient for nonlinear optical applications. Nonlinear optics facilitates interaction of photons with each other and with other physical systems, and is of prime importance in quantum optics. In this paper we review numerous applications of WGM resonators in nonlinear and quantum optics. We outline the current areas of interest, summarize progress, highlight difficulties, and discuss possible future development trends in these areas.Comment: This is a review paper with 615 references, submitted to J. Op