Surge Signal Research Articles

Functional characterization of follicle-stimulating hormone and luteinizing hormone receptors in cloudy catshark, Scyliorhinus torazame

The follicle-stimulating hormone receptor (FSHR) and luteinizing hormone receptor (LHR) in cloudy catshark were cloned, and recombinant FSHR and LHR were expressed for characterization. Ventral lobe extract (VLE) from the pituitary contains homologous FSH and LH, and it stimulated the cAMP signaling of FSHR and LHR dose-dependently. Two transcript variants of LHR (LHR-L with exon 10 and LHR-S without) were identified, and LHR-S was the dominant form with higher basal cAMP activity without VLE stimulation. Among various developmental stages of follicles, FSHR expression was mainly associated with the pre-vitellogenic and early white follicles. When follicles were recruited into vitellogenesis, the expression of FSHR decreased while of LHR was upregulated reciprocally, suggesting that LHR may also be responsible for the control of vitellogenesis in chondrichthyans. The expression of LHR-L was upregulated among maturing follicles before ovulation, indicating LHR-L could have a specific role in receiving the LH surge signal for final maturation. Plasma LH-like activity was transiently increased prior to the progesterone (P4)-surge and testosterone-drop at the beginning of P4-phase, supporting a pituitary control of follicle-maturation via LH signaling in chondrichthyans. The expression of follicular LHR was downregulated during the P4-phase when LH-like activity was high, indicating that the LH-dependent downregulation of LHR is conserved in chondrichthyans as it is in other vertebrate lineages. (213 words)

Surge detection of magnetic suspension fluid machinery based on rotor axial displacement signal and normalized second-order generalized integrator-frequency locked loop with prefilter

A surge detection method according to rotor axial displacement signal and normalized second-order generalized integrator-frequency locked loop with prefilter (SOGI-FLL-WPF) is proposed to solve the surge detection problem of magnetic suspension fluid machinery, which has important practical significance. To improve the anti-disturbance performance of surge detection, SOGI is introduced as a prefilter. As a prefilter, SOGI can eliminate the interference in the surge signal, and normalized SOGI-FLL can estimate the amplitude and frequency of the surge signal. Normalized SOGI-FLL and prefilter are combined to form normalized SOGI-FLL-WPF. First, the disturbance transfer model between rotor axial displacement signal and pressure signal is deduced. Then, the surge is detected by normalized SOGI-FLL-WPF. This method has the merit of fast response, small computation, and good disturbance resistance without additional detection units. Finally, the test is implemented on 105 kW and 150 kW magnetic suspension blowers. The results demonstrate that the proposed method can quickly detect surge signal after the surge occurs.

Adaptive surge detection of magnetic suspension centrifugal blower based on rotor radial displacement signal and SOGI-FLL with prefilter

For the surge detection problem of high-speed magnetic suspension centrifugal blower, a second order generalized integral-frequency locked loop with prefilter (SOGI-FLL-WPF) is used for surge detection. This method is utilized to normalize the amplitude and frequency of the surge signal by using the rotor radial displacement signal in the magnetic suspension blower. So that the response speed of detecting surge signal is not affected by the frequency and amplitude, and the frequency of the blower surge vibration signal is tracked adaptively. As a result, the fast response ability of the surge signal detection is improved. Specifically, firstly, the rotor radial displacement signal is collected in real time. And then, the rotor speed is identified by SOGI-FLL, and the identified speed information is input to SOGI for notch. Finally, the surge detection is carried out by SOGI-FLL-WPF for the signal after notch. The 105 kW magnetic suspension centrifugal blower is applied for the surge detection experiment. The experimental results show that the surge detection method based on rotor radial displacement signal and SOGI-FLL-WPF can detect the surge signal immediately after its occurrence. The proposed detection method needs no additional detection unit, and has the advantages of simple algorithm, fast response speed and small amount of calculation. In addition, it can effectively reflect the change of frequency in the process of surge.

A coupled wave, tide and storm surge operational forecasting system for South Africa: validation and physical description

Regional storm tidal levels of the South African coastline are investigated by means of a calibrated and validated numerical model. The model was developed utilizing the shallow water hydrodynamic model, Delft3D. This model was coupled (online) with a non-stationary spectral wave model (developed in the Simulating WAves in the Nearshore (SWAN) numerical code). A local, 4.4 km version of the Unified Model was applied as atmospheric forcing for the coupled system. The models presented in this study form part of the operational marine forecasts of the South African Weather Service, Wave and Storm Surge model. The operational protocol and model calibration and validation are presented via statistical correlations with measured water levels at six South African coastal locations. The main calibration parameters and thus physical drivers were winds, atmospheric pressure and waves. The validated numerical model is used to provide an experimental physical description of South African storm surge characteristics, per coastline. The dominant driver of South African storm surge is winds associated with mid-latitude cyclones. Further novelty in the present study is the quantification of the relative contribution of extreme storm wave set-up to the South African storm surge signal. This wave set-up contributes approximately 20% of the total surge signal in the southwest, with winds contributing approximately 55%. The importance of the continental shelves is also elucidated concerning the frictional shoaling effects of the long surge wave propagation.

Surge Compression for Improved Fault Location Accuracy in Full Transient-Based Methods

This paper proves that the accuracy of single-ended fault location techniques based on the correlation of fault transients in power lines can be significantly improved by inverse-filtering transients first. The reason for this improved accuracy is found in the reduction of the duration of the fault surge signal, thus increasing the sensitivity of fault-location metrics to the fault position. Reported results show that by using the proposed filtering strategy, faster sampling rates systematically and significantly improve the location accuracy, as opposed to the case when no filter is applied, for which virtually no improvement is observed. Because of its higher spatial selectivity, the proposed fault-location technique required the development of a new synchronization method, which ensures a precise transient synchronization without the need for high-speed sampling. It is concluded that by jointly using the proposed transient filtering and synchronization solutions, correlation-based fault location can be significantly improved even when using sampling rates as low as 100 kHz. Extensive numerical simulations for a three-phase transmission line confirm an improvement exceeding one order of magnitude in the fault location accuracy, for both low- and high-impedance faults.

Online Surge Detection Method Based on Axial Displacement Sensor of MSCC

Magnetically suspended centrifugal compressor (MSCC) can get higher speed with no friction and improve transformation efficiency. However, with speed increases, air flows more easily to separate from the blade and cause the gas pressure unsteadily, which leads to surge occur, causing the system destroyed. Aiming at the problem that existing surge detection methods usually increase complexity or cannot detect surge in time, this paper proposes an online surge detection method and corresponding surge judgment criteria of MSCC system using the signal of axial displacement sensor based on adaptive interference canceller (AIC) and average phase forward linear predictor (APFLP). At first, the system model of the MSCC is established and the transfer function between surge pressure signal and rotor displacement signal is derived. On these basis, an AIC is designed to eliminate the synchronous vibration signal, which has serious interference to surge detection and an APFLP is designed to estimate the frequency of the surge signal. Finally, the simulation and experimental research of the new method are carried out. The simulation and experimental results show that the method can detect surge quickly and effectively.

Surge Detection Approach for Magnetically Suspended Centrifugal Compressors Using Adaptive Frequency Estimator

The active surge suppression is a challenging topic in the industrial compressor systems. This paper addresses the two issues on the surge detection approach for magnetically suspended centrifugal compressors (MSCCs) utilizing the signal monitoring capabilities of magnetic bearings. An adaptive frequency estimator is proposed to extract the surge signal, and a judgment criterion is establish to the surge state. First, the derivation of a surge disturbance transfer model for the fluctuating pressure and rotor displacement was presented, and the characteristics of surge signal in the MSCC system is analyzed. Then, a conventional notch filter (NF) is used to eliminate the synchronous disturbance in the surge signal, and a modified adaptive notch filter (ANF) method is used to estimate the frequency of surge signal. The convergence analysis of the modified ANF shows that the linearized system is asymptotically stable. The mild surge detection technology and judgement criterion are also discussed. Experimental results on both the 100 kW and 315 kW MSCC systems show that the proposed method can rapidly detect the surge before the MSCC systems develops into the modified surge.

Relative Contribution of Wave Setup to the Storm Surge: Observations and Modeling Based Analysis in Open and Protected Environments (Truc Vert beach and Tubuai island)

Pedreros, R.; Idier, D.; Muller, H.; Lecacheux, S.; Paris, F.; Yates-Michelin, M.; Dumas, F.; Pineau-Guillou, L., and Senechal, N., 2018. Relative contribution of wave setup to the storm surge: observations and modeling based analysis in open and protected environments (Truc Vert beach and Tubuai island). In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1046–1050. Coconut Creek (Florida), ISSN 0749-0208.Recent events like the Xynthia (2010, France) storm illustrate the potentially devastating effect that storm surges can have on the coasts. Nearshore storm surges at the result mainly from two processes: atmospheric surges and wave setup. This paper investigate the relative wave setup contribution in the storm surge signal for energetic events and focusing on two cases: an open beach (Truc Vert beach, France) and a high island protected by a reef lagoon (Tubuai, French Polynesia). The two selected events are the Johanna storm (March'08), for the Truc Vert site, and the Oli cyclone (February'10), for Tubuai. The data analysis shows that the maximum total storm surge reaches 1.2 m on the Truc Vert site and 1.1 m in the Tubuai lagoon. On the Truc Vert beach, the ECORS'08 in-situ measurements allow estimating a wave setup contribution of 80% of the total storm surge, at the time of maximum storm surge. The relative contribution of the wave setup is investigated a bit further, using the modeling approach. The modeling relies on the joint use of a shallow-water (MARS 2DH) and wave (SWAN) models. It shows an heterogeneous distribution of the wave setup in the Tubuai lagoon and a longshore variability close to the waterline for Truc Vert (~ 30%). In both cases, the wave setup contribution to the whole storm surge is predominant, with relative values ranging from 71 to 120% of the total maximal storm surge. Values larger than 100% occur on the Tubuai site when the atmospheric storm surge is negative.

Electronegativity of capacitively coupled Ar+O2 plasma excited at very high frequency

By using pulsed laser induced detachment technique assisted with a Langmuir probe, the electronegative characteristics of the capacitively coupled Ar plasma doped with 5% O2 are studied in this paper. We first focus on the electrical signal of the probe after laser pulse has induced negative ion detachment, and then analyze characteristics of the probe signal with the probe bias below or above the plasma space potential. When the bias is set to be lower than the plasma potential, the probe signal usually shows a downward surge signal. As the bias is higher than the plasma potential, the main characteristics of the signal takes on an upward wide wave packet. The evolution behavior of the probe signal with bias from the downward surge valley to the upward wide wave packet might be due to the potential difference between the plasma space potential and the probe bias voltage. Furthermore, it shows that the position of the upward peak appears later than that of the downward surge valley, which may be related to the changing of the rate of the electron diffusion flux and the electric field drift flux. According to the dependence of probe collection signal on bias, the electronegativity describing the Ar+O2 plasma electronegative property is defined as saturation ratio of electron current after pulsed laser radiation to that of collection probe at a potential above plasma spatial potential. Plasma electronegativity is diagnosed with discharge pressure, radio-frequency (RF) input power and axial position. The experimental results show that the electronegativity of plasma decreases with input RF power increasing. As the gas pressure is kept at 12.0 Pa, the plasma electronegativity decreases from 5.05 to 0.98 with RF input power increasing from 50 to 300 W. It also shows an increasing trend of electronegativity with plasma discharge pressure increasing. Due to asymmetrical distribution of electrodes, the plasma electronegativity also takes on asymmetric one with respect to the axial position. In our experiments, the electronegativity near the power electrode shows about 1-4 times higher than that near the ground electrode, the lowest point of the plasma electronegativity seems to be located in the center of the plasma discharge. This may be related to the dynamics of the secondary electrons emitted from electrode and the competition processes between negative ion production in collisional dissociation of oxygen molecules and the losses of high energy electron and negative ion in collisional detachment of negative ion with oxygen molecule.

InSAR observations and models of crustal deformation due to a glacial surge in Iceland

Surges are common at all the major ice caps in Iceland. Ice masses of gigatons may shift from the upper part of the outlet glacier towards the terminus in a few months, advancing the glacier front by up to several kilometres. The advancing ice front may be up to 100 m thick, increasing the load on crustal rocks correspondingly. We use the observed change in crustal loading during a surge of the western part of the Vatnajokull ice cap, Iceland, during 1993–1995 and the corresponding elastic crustal deformation, surveyed with interferometric synthetic aperture radar, to investigate the material properties of the solid Earth in this region. Crustal subsidence due to the surge reaches ∼75mm at the edge of the Siðujokull outlet glacier. This signal is mixed with a broad uplift signal of ∼12 mm/yr, relative to our reference area, caused by the ongoing retreat of Vatnajokull in response to climate change. We disentangle the two signals by linear inversion. Finite element modelling is used to investigate the elastic Earth response of the surge, as well as to confirm that no significant viscoelastic deformation occurred as a consequence of the surge. The modelling leads to estimates of the Young’s modulus and Poisson’s ratio of the underlying Earth. Comparison between the observed and modelled deformation fields is made using a Bayesian approach that yields the estimate of a probability distribution for each of the free parameters. Residuals indicate a good agreement between models and observations. One-layer elastic models result in a Young’s modulus of 43.2–49.7 GPa (95 per cent confidence) and Poisson’s ratio of 0–0.27, after removal of outliers. Our preferred model, with two elastic layers, provides a better fit to the whole surge signal. This model consists of a 1-km-thick upper layer with an average Young’s modulus of 12.9–15.3 GPa and Poisson’s ratio of 0.17, overlying a layer with an average Young’s modulus of 67.3–81.9 GPa and Poisson’s ratio of 0.25.

ANALYSIS OF EXCITATION PULSED SIGNAL PROPAGATION FOR ATOM PROBE TOMOGRAPHY SYSTEM

The purpose of this paper is on the behavioral modelling of surge voltage pulses used in Atom Probe Tomography. After brief description of the atom probe functioning principle, we examine the excitation electrical pulse signal integrity along the electric pulser (E-pulser) feeding line modelling with respect to the IEC1733/04 standard. This feeding electric line is ended by cylindrical via ground to control the ion emission. By using the transmission line (TL) ultra-broadband RLCG model, the propagating pulsed signals degradation is predicted. The signal propagation was analysed in both frequency and time domains by taking into account the substrate dispersion. The wideband frequency behaviours of the surge signal along the feeding line were examined from DC-to-2GHz. In addition, by considering pulse surge signals with pulse-width and rise-/fall-time parameters (T1 = 9ns, tr1 = tf1 = 1:6ns) and (T2 = 30ns, tr2 = 4ns/tf2 = 18ns), the transient responses from 5cm-to- 20cm length TL are characterized. It was shown that the excitation pulse was signiflcantly distorted. It was emphasized that the operated signal delay varies from 0.3ns-to-1.5ns in function of the via capacitor value. The time-dependent radiated E-fleld on the performance of the atom probe system which enables to characterize the nature of tested materials (ions or atoms) is discussed. The presented analysis approach is particularly useful for E-pulser integrated in measurement scientiflc instruments as Atom Probe Tomography time of ∞ight optimisation, a nano-analysing technique that uses ultra-sharp high vacuum pulse to induce controlled erosion of samples. In this application, the excitation voltage pulse integrity during the propagation is required in order to improve the measurement instrument performances.

A linguistic decision tree approach to predicting storm surge

A linguistic decision tree algorithm (LID3) is applied to the problem of predicting storm surge. Of particular interest is the prediction of large positive storm surge for flood warning purposes. The application site is the North Sea which has a well-understood physical system for the generation and progression of storm surge, which lends itself to testing of the LID3 algorithm on a real-world prediction problem. Using available water level and meteorological data, the decision tree provides predictions of surge on the Thames Estuary up to 8h in advance, accurate to the order of 0.1m, which is comparable to alternative data driven methods. However, the success of the data driven approaches applied here are all limited by the sparsity of training data for extreme events (which by their nature are rare). A major benefit of the decision tree approach is the ability to make inference from the resulting IF–THEN rules of the tree structure. In this application of the LID3 algorithm, clear and plausible model rules can be deduced from the tree structure that are consistent with our understanding of the physical drivers of storm surge at this location. The label semantic framework is interpreted probabilistically, allowing the user to employ standard statistical approaches to identify statistically significant rules. It is demonstrated that the rules can successfully discriminate between surges that may pose a threat and those that should not, based on tide gauge measurements available up to 8h prior to the surge signal reaching the Thames Estuary. This is promising for the potential application of such computationally efficient and easy to implement rule learning algorithms for the further investigation of complex environmental systems.

Operational forecasting of sea level height using an unstructured grid ocean model

Unstructured grid models are often used for modelling coastal problems, due to their efficiency at handling complex coastlines while also not over resolving deeper water. In this paper, we outline how an unstructured grid finite element model has been incorporated into an operational environmental forecast system, EcoConnect, to provide near real-time predictions of storm surge and sea level height. Data transfer methods between the meteorological model, which uses a structured grid, and the storm surge model are described and we present results of verification simulations for the forecasting of sea level height. The model successfully reproduced the storm surge signal at 15 tide gauge locations around New Zealand during December 2006–February 2007, with RMS errors in the range 3–7 cm. Preliminary tests of a tide model using the same unstructured grid are also presented, as a precursor to its inclusion into the operational system.

Sea-State-Dependent Momentum Fluxes for Ocean Modeling

Abstract The impact of wave-dependent surface stress on the ocean circulation has been studied using surface stresses calculated from a numerical wave model. The main questions to be investigated were what the effect would be on the Ekman currents in the upper ocean and what the impact would be on storm surge predictions. To answer the first question, the response of wave-dependent forcing on an Ekman type of model was studied. Here, the wave forcing was provided by a one-gridpoint version of the wave model. Second, the impact of the waves was studied with a three-dimensional ocean circulation model for the North Sea. Three different experiments were performed for a period of 1 yr. To test the effect on the storm surge signal, the results have been compared with sea level observations from 22 stations along the Norwegian and Dutch coasts. One of the main findings is that calculating stresses in the wave model, thereby introducing sea-state-dependent momentum fluxes, has a strong positive impact on the storm surge modeling compared with applying a traditional parameterization of surface stresses from the 10-m wind speed. When all cases with sea level deviation from the mean of less than 0.5 m were removed, the root-mean-square error for 1 yr averaged over all stations was reduced by approximately 6 cm. Splitting the momentum budget into an Eulerian and a wave part (Stokes drift) has only a negligible effect on the modeling of the sea surface elevation but increases the angular turning of the Eulerian surface drift to the right of the wind direction with an angle of about 4°.

Influence of non-linear effects upon surge elevations along the west coast of Britain

A two-dimensional vertically integrated hydrodynamic finite-element model of the west coast of Britain is used to examine the response of the region to extreme meteorological forcing. The extent to which tide–surge interaction modifies the computed surge elevation and current distributions is examined in detail. The nature of the finite-element model with its ability to refine the mesh in nearshore regions is ideal for examining the influence of non-linear effects upon surges in these regions. Calculations using spatially uniform orthogonal wind stresses show that the surge elevation and current in shallow water are particularly sensitive to the method used to remove the tide as a result of the highly non-linear nature of the tide–surge interaction in these regions. The most accurate means of de-tiding the solution is by subtracting a tide derived by harmonic analysis of the tide and surge time series at the time of the surge. Subtracting a tide-only solution (the usual approach) leads to tidal energy leaking into the surge solution. Calculations show that this arises because the surge modifies the tidal amplitude and phase in shallow-water regions to such an extent that they are appreciably different to those found in the tide-only calculation. Results suggest that this problem becomes more important, as nearshore meshes are refined in an attempt to improve surge prediction. This suggests that in the future, highly accurate fine-mesh models will be required to compute total water levels without the present linear separation into tidal and surge signal used in operational surge prediction.

Extreme Sea-level Distribution and Return Periods in the Aegean and Ionian Seas

Extreme sea levels from 18 ports in the Aegean and Ionian Seas were analysed in the present study. The joint probability of ther-largest annual sea-level observations and the revised joint probability method have been used. Return periods and associated errors are produced from the two methodologies. The estimated return values are shown to be spatially coherent with enhanced values at the tide gauges located in the North Aegean and in enclosed gulfs. In spite of the low tidal and surge signal in the area, the estimated return values depend on the model chosen to represent the asymptotic distribution of the maxima of sea level.

Temperature dependence of terahertz pulses produced by difference- frequency mixing in InSb

Terahertz radiation emitted from (111) InSb illuminated with focused 1.4 μm laser pulses is due to both difference-frequency mixing and depletion field driven current. By rotating an undoped (111) InSb sample at a temperature of 80 K about its surface normal, we were able to separate the relative contribution of the azimuthally dependent difference-frequency mixing (DFM) signal from the total terahertz wave form. Contrary to expectations, it was found that the azimuthally dependent spectrum appears nearly identical to the azimuthally independent spectrum. From this, it is concluded that the spectrum of the current surge signal blue shifts as the pump is focused. Also, a strong similarity exists between the temperature dependence of the DFM and current surge signals.

An insulator coupled surge receiving equipment for fault locator using optical fiber cable

Electric Power Development Co. has been developing new surge receiving equipment which is coupled with an insulator and transmits the received signal through an optical fiber cable. In this paper, the results of experiments on the insulator coupled surge receiving equipment for fault locator using optical fiber cable are reported. It is confirmed that it is possible to receive accurately the fault surge voltage with peak voltage of 60 kV and higher and build-up time of 0.5 - 20 ..mu..s. The test results show that it is possible to use the surge receiving fault locator without using a conventional type coupling condenser. Since the suspension insulator string or the low capacitance gas insulated potential device can be used, the proposed equipment brings about a great economic benefit. Use of the optical fiber cable also makes it possible to receive the surge signal with good S/N ratio and to realize a highly reliable fault locator.

Effects of morphine and naloxone on phasic release of luteinizing hormone and follicle-stimulating hormone.

SummaryIn ovariectomized rats given estradiol benzoate (EB), followed 3 days later by EB or progesterone, morphine, and naloxone altered the LH and FSH surges on the day of treatment (Day 1) and on the next day (Day 2). In the EB-EB-treated rats, morphine prevented, whereas naloxone enhanced the surge of LH and FSH on Day 1. On Day 2, the morphine-treated rats showed a large rebound surge of LH and FSH, whereas the naloxone-treated rats showed no surge. In the EB-progesterone-treated rats, morphine blocked, whereas naloxone had no effect on the LH and FSH surge on Day 1. On Day 2, the morphine-treated rats showed a large LH and FSH surge, whereas the naloxonetreated rats showed no surge. The effects of these drugs on the Day 2 surge of LH and FSH were found not to be the result of a build up or depletion of releasable stores of LH in the pituitary on Day 1. These results suggest a possible role for the endogenous opioid peptides in modulating steroid regulation of the neural surge signal for LH and FSH.