PD Measurements Research Articles

Estimating the size of an earthquake using short-period seismograms of the first three seconds: A simulated experiment using the 1999 Chi-Chi earthquake sequence

Most of the present earthquake early warning systems are based on broadband or strong motion recordings. However, the short-period instruments are still deployed. It is well-known that short-period recordings have saturation problems for large earthquakes when estimating the size of an earthquake. Thus, it is necessary to make clear the magnitude at which saturation starts to occur for the commonly used τc and Pd measurements, respectively. To investigate the possibility of using short-period seismic recordings for earthquake early warning, we conducted a simulated experiment using the strong motion data of the 1999 Chi-Chi earthquake sequence including its main shock and 31 aftershocks, with magnitude span from 4 to 7.6. The strong motion acceleration recordings were convolved with the instrument response of short-period seismographs in northern China to simulate short-period seismograms. Parameters τc and Pd from the first-three-second seismograms were calculated for the simulated short-period recordings and compared with that obtained by the original strong ground motion recordings. The result showed that to some extent, short-period recordings can be used for threshold earthquake early warning, while the magnitude saturation of Pd estimation can be up to 6.5, better than τc estimation.

A Lock-in Technique for PD Measurement during Impulse Tests

A method is proposed for recognizing PD events within a winding during impulse tests using a lock-in amplifier technique. The resonant frequencies of the winding serve as the basis of selection of the lock-in amplifier reference frequencies. It is implemented with a virtual instrument and validated with an independent stand-alone lock-in amplifier. A physical model of a winding with discrete elements is used to demonstrate the results. A theoretical basis for the instrument is established using an 'abc' model of PD along with a linear discrete winding model. The influence of location of PD is also addressed. The method will provide online recognition of PD during the impulse test and can be adapted for onsite measurements.

Nocturnal transpiration causing disequilibrium between soil and stem predawn water potential in mixed conifer forests of Idaho

Soil water potential (Psi(s)) is often estimated by measuring leaf water potential before dawn (Psi(pd)), based on the assumption that the plant water status has come into equilibrium with that of the soil. However, it has been documented for a number of plant species that stomata do not close completely at night, allowing for nocturnal transpiration and thus preventing nocturnal soil-plant water potential equilibration. The potential for nighttime transpiration necessitates testing the assumption of nocturnal equilibration before accepting Psi(pd) as a valid estimate of Psi(s). We determined the magnitude of disequilibrium between Psi(pd) and Psi(s) in four temperate conifer species across three height classes through a replicated study in northern Idaho. Based on both stomatal conductance and sap flux measurements, we confirmed that the combination of open stomata and high nocturnal atmospheric vapor pressure deficit (D) resulted in nocturnal transpiration in all four species. Nocturnal stomatal conductance (g(s-noc)) averaged about 33% of mid-morning conductance values. We used species-specific estimates of g(s-noc) and leaf specific conductance to correct Psi(pd) values for nocturnal transpiration at the time the samples were collected. Compared with the unadjusted values, corrected values reflected a significantly higher Psi(pd) (when D > 0.12 kPa). These results demonstrate that comparisons of Psi(pd) among species, canopy height classes and sites, and across growing seasons can be influenced by differential amounts of nocturnal transpiration, leading to flawed results. Consequently, it is important to account for the presence of nocturnal transpiration, either through a properly parameterized model or by making Psi(pd) measurements when D is sufficiently low that it cannot drive nocturnal transpiration. Violating these conditions will likely result in underestimation of Psi(s).

Effect of supply voltage frequency on testing of insulation system

This paper investigates a subject of high practical importance and proposes representative frequency range definition for HVAC testing with PD measurement which can improve both, on-site and laboratory testing. It will also strengthen the clear connection between stresses in service and HVAC testing. Furthermore it creates the correspondence between on-line PD monitoring and off-line PD testing

고압전동기 고정자권선의 절연결함에 대한 특징추출기법

Multi-resolution Signal Decomposition (MSD) Technique of Wavelet Transform has interesting properties of capturing the embedded horizontal, vertical and diagonal variations within an image in a separable form. This feature was exploited to identify individual partial discharge sources present in multi-source PD pattern, usually encountered during practical PD measurement. Employing the Daubechies wavelet, feature were extracted from the third level decomposed and reconstructed horizontal and vertical component images. These features were found to contain the necessary discriminating information corresponding to the individual PD sources and multi-PD soruces.

Hydrogen permeability of multiphase V–Ti–Ni metallic membranes

Development of advanced hydrogen separation membranes in support of hydrogen production processes such as coal gasification and as front end gas purifiers for fuel cell based system is paramount to the successful implementation of a national hydrogen economy. Current generation metallic hydrogen separation membranes are based on Pd-alloys. Although the technology has proven to be successful, at issue is the high cost of palladium. Evaluation of non-noble metal based dense metallic separation membranes is currently receiving national and international attention. The focal point of the reported work was to evaluate a Group 5A-Ta, Nb, V-based alloy with respect to microstructural features and hydrogen permeability. Electrochemical hydrogen permeation testing of the V–Ti–Ni alloy is reported herein and compared to pure Pd measurements recorded as part of this same study. The V–Ti–Ni was demonstrated to have a steady-state hydrogen permeation rate an order of magnitude higher than the pure Pd material in testing conducted at 22 °C.

Atypical CF and CF related diseases

The clinical characteristics of atypical CF are: symptoms that may start in infancy but the disease become clinically significant only after 10 years of age, survival into adulthood, chronic sinopulmonary disease, pancreatic sufficiency, and sweat chloride <60 meq/L. Other patients may present with single organ involvement such as CBAVD, biliary cirrhosis and portal hypertension, chronic or recurrent pancreatitis, giant nasal polyposis or hypochloremic alkalosis. It is recommended to refer such patients for CFTR genotyping, however, absence of known common mutation does not rule out CFTR associated disease, since mutations causing atypical CF are rare and whole genome scan is required for their identification. Nasal PD measurements may be helpful to establish the diagnosis of these patients; however, measurements might be also atypical. Several explanations have been suggested to explain the atypical CF disease.

Pharmacokinetics and pharmacodynamics of benidipine using a slow receptor-binding model

This study examined the relationship between the plasma concentration of benidipine, a long-lasting antihypertensive agent with Ca(2+)-channel-blocking properties, and its cardiovascular effects (reduction in blood pressure and increase in heart rate) in order to assess the usefulness of pharmacokinetic-pharmacodynamic (PK-PD) modelling in describing this relationship. Two groups of 24 healthy volunteers received either a 4- or 8-mg benidipine hydrochloride tablet; 11 additional subjects received a placebo. Serial blood sampling and PD measurements were performed over 8 h thereafter. Plasma concentrations of benidipine were measured with a validated LC/MS/MS system, and the effects on blood pressure and heart rate were assessed during the same period. A two-compartment open model with lag time was used to explain the PK properties, and the PD model was characterized by slow receptor binding, reflecting the binding of benidipine to the ion-channel receptor. Benidipine reached mean peak plasma concentrations of 1.04 and 3.85 ng/mL at 0.5 and 0.75 h after 4 and 8 mg doses, respectively. Peak cardiovascular effects were detected approximately 2 h after the administration of either dose. Maximal decreases in diastolic blood pressure with 4 and 8 mg of benidipine were 7.79 and 14.75 mmHg, respectively, and maximal increases in heart rate were 7.32 and 17.56 bpm, respectively. No significant changes in systolic blood pressure were observed. The cardiovascular effects were analysed according to a slow receptor-binding model. The tested PK-PD model successfully described the relationship between the plasma concentration of benidipine and its cardiovascular effects.

Partial discharge factory test requirements and in-field partial discharge testing of medium voltage cables

This article presents partial discharge testing of medium voltage cables. Utility engineers are faced with decision on whether to replace some of the older cables in their underground distribution systems. Today, measurement of PD at voltages above 1 Vg on extruded cables more than fifteen years old may not indicate that the cables have developed PD due to in-service aging. Removal of these cables based solely on PD measurements may not be warranted. Failure history of the cable, in conjunction with an analysis of the PD site, should be part of the utility engineer's decision-making process.

PK and PD of recombinant human IL-18 (rhIL-18) administered IV in repeated cycles to patients with solid tumors

2535 Background: rhIL-18, a potent immunomodulatory cytokine, has demonstrated anti-tumor activity in a variety of preclinical models. Clinical safety and biological activity were examined in a previous study of rhIL-18 administered in a single cycle at IV doses ranging from 3 - 1000 mcg/kg/day for 5 days. The current study examined the effects of administering repeated cycles, and the resulting PK exposure and PD biomarker response data, which are described below. Methods: Three cohorts of 3 patients each were enrolled (6 with melanoma and 3 with metastatic renal cell carcinoma), and received 100, 500, or 1000 mcg/kg doses of rhIL-18 (SB485232) administered as 2h infusions daily for 5 consecutive days every 28 days in repeated cycles (up to 6). Assessments included tolerability, immunogenicity, anti-tumor activity, PK, and biomarkers of immunomodulatory activity. PK and PD measurements were made on Days 1 and 5 of Cycles 1 and 2. Plasma drug concentrations were measured by ELISA. Cytokine/protein biomarkers were measured by ELISA and custom cytokine multiplex biochips. Cell activation biomarkers were measured by flow cytometry. Results: Plasma concentrations of rhIL-18 increased with increasing dose, were comparable between cycles, and exhibited 3-fold accumulation over 5 days with a half-life of 39h. Induction of IFN-gamma, GM-CSF, TNF-alpha, IP-10, MIG, MCP-1, and IL-18 Binding Protein (BP) was observed. These responses were attenuated in the second cycle. Cytokine and chemokine responses were also attenuated within each cycle (Day 5 vs Day 1). Lymphopenia and expression of CD69 on CD4, CD8, and NK cells were maximal 6h after the first infusion at all doses in each cycle, with no apparent attenuation of response. Conclusions: These data suggest that rhIL-18 induces inflammatory cytokine production and cell-mediated immunological activation. The apparent attenuation of cytokine responses with repeated exposure may be due in part to the regulatory effect of BP. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration GlaxoSmithKline

A phase I study of a humanized monoclonal anti-epidermal growth factor receptor (EGFR) antibody “EMD72000 (Matuzumab)” administered weekly in Japanese patients with advanced solid tumors; safety, PK and PD results of skin biopsies

3077 Background: Matuzumab is a humanized monoclonal antibody binding to the EGFR with higher affinity than natural ligands (eg. TGF alpha,EGF) leading to inhibition of signal transduction pathways which are activated through ligand-binding and subsequent phosphorylation. Matuzumab has shown anti-tumor activity in xenograft models. Several clinical studies, which showed to be effective, have already been conducted in Europe and the US.Methods: We have conducted a phase I study of matuzumab administered as a 1 hour IV infusion weekly at 4 fixed doses: 400mg, 800mg, 1200mg and 1600mg. PK samples from different timepoints and PD using skin biopsies were also investigated. The primary objective was to assess safety profile of EMD72000 as single agent. The secondary objectives were DLT assessment, PK, PD, tumor response and human anti-humanized antibody (HAHA) measurement. PD studies determined the occurrence of protein makers related to EGFR signaling pathways in skin biopsies taken before and on day 29 (pEGFR, pMAPK, Ki67) by IHC. Results: A total of 26 pts (400mg; 6pts, 800mg; 7pts, 1200mg; 7pts, 1600mg: 6pts;doses were not adjusted to BM or BSA) with EGFR+ tumors have been included: colorectal (18), gastric (7) and esophagus (1), median age of 61 (range: 33–72), and a median of 2.5 prior chemotherapy regimens (range: 1–5). One subject occurred with DLT at 1600mg (increased total-bilirubin). However, other toxicities were Grade 1 - 2 in severity. There have been 2 PR, and 10 SD in pt with colon cancer. EMD72000 exposure increased in proportion to dose with slightly higher values for the 1200mg dose group. Half life was around 110h for all dose groups. PK data were consistent with results of other studies of EMD 72000 monotherapy. Preliminary analysis of the PD assessments showed that matuzumab produced complete inhibition of pEGFR & pMAPK at higher doses with a decrease in Ki67 and an increase in p27 in skin samples even in the lowest dose group.Conclusions: Matuzumab in biologically effective doses appeared very well tolerated. PD and PK data corresponded to recent study results of matuzumab monotherapy. No significant financial relationships to disclose.

On line pd measurements and diagnosis on power transformers

On line partial discharge (PD) measurements provide information on the dielectric integrity of the high voltage insulation of oil insulated power transformers during service. These PD measurements are performed using a broadband antenna on an oil valve and UHF detection of PD signals. The sensitivity of this new detection technique is high and immunity for electromagnetic (EM) interference and corona discharges in air outside the transformer is very good. Dielectric faults can be detected in this way in an early stage of development and are classified in four categories. Automatic pattern recognition techniques of phase resolved pulse sequence (PRPS) data are very useful in risk assessment of dielectric faults.

Sensitive Online PD-Measurements of Onsite Oil/Paper-Insulated Devices by Means of Optimized Acoustic Emission Techniques (AET)

Recently developed monitoring-systems show the need as also the possibilities for online- and offline-onsite-diagnostics. The limit in sensitivity for electrical pd-measurements according to IEC 60270 which is reached using filters for sinusoidal disturbances and compensation for corona impulses is still not satisfactory. The acoustic partial discharge measurement (pd-measurement) is also a well known and reliable method often used by transformer manufacturers in testing. In laboratory setups a gain in sensitivity of the acoustic in comparison to the electrical pd measurements could be established. This is reached by adapting the sensors to the propagation path, a modern but moderately priced acquisition hardware and the introduction of new signal processing algorithms. The developed sophisticated measuring systems show remarkable results in online acoustic pd-measurements onsite.

507. Down-Regulation of the Epithelial Sodium Channel ENaC through Antisense Oligonucleotides

Sodium absorption across the airway epithelium is increased in cystic fibrosis (CF) patients and may contribute to abnormal water transport and accummulation of sticky sputum, a hallmark of the CF lung disease. Down-regulation of epithelial sodium channels (ENaC) may attenuate the CF lung disease. One approach to decrease ENaC function is the specific down-regulation of its mRNA. Single-stranded DNA antisense oligonucleotides (ssDNA) bind to mRNA sequence-specifically and trigger RNase-H mediated degradation of the ssDNA/mRNA hybrid. However, careful selection of the ssDNA sequence is required to obtain optimal mRNA reduction. Here, we compared five murine ENaC antisense DNAs (20 nucleotides each) for their ability to decrease ENaC mRNA in M1 cells, a murine kidney cell line that expresses ENaC abundantly. It has previously been demonstrated that the alpha subunit of ENaC is the most crucial for channel function and all five ssDNAs were therefore directed against this subunit. First, fluorescently labelled ssDNA was complexed with Lipofectamine 2000 and transfection efficiency determined. Interestingly, the ssDNA rapidly (after 30 min) accumulated in the nucleus of transfected cells and after 6 hrs >90% cells were transfected. The nuclear localisation of the antisense ODNs was consistent with their proposed site of action. Forty-eight hrs after transfection cells were harvested and mRNA was prepared for quantitative RT-PCR using Taqman. The relative degree of aENaC mRNA reduction varied between antisense molecules and ranged from 5 to 60% (n=6, p<0.05). The most efficient ssDNA was used for in vivo transfection. Genzyme lipid 67 (GL67) has been widely used for gene transfer in vivo, but not for antisense applications. We first assessed if GL67 complexed antisense ssDNA efficiently. Gel retardation studies showed that with a 6:8 molar ratio of cationic lipid:nucleotide almost all ssDNA was complexed (n=3). Light-scatter analysis showed that complexes had an average size of 390±24 nm, but varied in size (n=3). Nasal potential difference assays (PD) have been widely used to measure ion transport across murine nasal epithelium. A decrease in ENaC function would result in a drop in baseline PD, because sodium transport is the main component of basal ion transport in the nasal mucosa. Here, we complexed aENaC antisense or control ssDNA to GL67 (80 mg/mouse) and perfused these complexes into the mouse nose over 75 min via a thin plastic catheter. Twenty-four, 48 and 96 hrs after administration the PD was measured in individual cohorts of animals (n=10/group). After the PD measurements all animals were culled and Taqman RT-PCR carried out on nasal mRNA. We did not detect a drop in aENaC mRNA or changes in PD at any time-point. A critical factor for antisense function in the mouse nose is transfection efficiency. In preliminary experiments (n=3) using fluorescently-labelled ODNs we noted that transfection efficiency varied drastically from animal to animal, and will therefore require further optimisation.

Change in PD pattern with aging

The changes in the PD /spl Phi/-q-n pattern and the PD current shape due to the degradation of insulating materials have been investigated with a fast digital oscilloscope and a PD measurement system. In order to verify the effect of gas change, the volume of gas in a void was observed with the /spl Phi/-q-n pattern. It showed that the change in the maximum PD magnitude is related to the change in gas volume according to ageing time. The PD /spl Phi/-q-n pattern could be classified into the five stages. At stage 3 for example, which had a "rabbit-like pattern", the current shape of the first PD in each half-cycle had a large magnitude of the order of 100 mA and a narrow width. At stage 5, which had a "turtle-like pattern", the current shape had a slow rise-time and a slow decay-time. Such changes in PD characteristics will be applicable to the diagnosis of insulation degradation.

About the significance of pd measurements in liquids

This paper presents investigations concerning the variations and significance of PD measurements in mineral oil, when detectors with different frequency response are used. Typical durations of discharge phenomena in liquids are much longer than in other media, and the measurement technique must be adapted accordingly. However, depending on the application concerned, this is not always possible. In this study, experiments and calculations are carried out to determine typical errors produced when classical RLC measurement impedances with various frequency responses are used to measure PD's in liquids. Experiments are done with corona and creeping discharges in mineral oil, and compared with corona and spark discharges in air. These examples allow us to conclude that when a calibrated high frequency PD measurement system is used, the ratio of measured to actual charge is much lower for discharges in liquids than in gases. If measurements are carried out on a practical device that may include various types of PD sources, the high frequency measurement system will strongly underestimate discharges in liquids compared to other discharge types. This discrepancy versus discharge type increases when the frequency response of the measurement system is increased.

Physiological responses of Fagus sylvatica L. seedlings under Pinus sylvestris L. and Quercus pyrenaica Willd. overstories

Water status and gas exchange of beech seedlings, planted in a scots pine stand (Pinus sylvestris L.) and a melojo-oak stand ( Quercus pyrenaica Willd.), were monitored during two growing seasons. In 1996, a very dry year, minimum predawn water potential ( Ψ pd±S.E.) of beech seedlings was, respectively, −1.88±0.13 and −1.11±0.07 MPa under the melojo oak and pine canopies; these values revealed higher water stress in the oakwood. Also a lower osmotic potential at full turgor ( Ψπ full) was measured under this canopy (−1.61±0.1 MPa versus −1.37±0.05 MPa in the pinewood) at the end of summer in both years. The higher osmotic adjustment that beech seedlings showed below the oak canopy was not enough to overcome the water stress they suffered at the end of summer 1996. The net photosynthesis ( A)—photosynthetic photon flux density (PPFD) relationship reflected the acclimatization of beech seedlings to a brighter environment under the oak canopy. It brought about higher A and water vapor stomatal conductance ( g wv) for a given PPFD level, but this response was only observed in dates with high water availability. Maximum values in the oak and pine stands were, respectively, 7.76±0.17 and 4.62±0.27 μmol m −2 s −1 for A max and 263±12 and 185±6 mmol m −2 s −1 for g wvmax. Differences in gas exchange between sites were more evident in 1997, as soil moisture and Ψ pd measurements were higher than in 1996 because a more rainy summer. This fact allowed the maintenance of higher gas exchange in beech seedlings growing under oakwood linked to their higher photosynthetic capacity.

Pd measurement system for predicting the long-term behaviour of ignition transformers

High requirements have to be met with regard to the quality of ignition systems due to the integration of power and sensor electronics in ignition transformers and the simultaneous more compact form of construction of Otto engines. This has to be proved by means of short-time tests with the newly-produced systems. Partial discharge diagnosis has been an important measure for quality checks in the field of high voltage engineering since many years. The use of partial discharge diagnosis for the prognosis of the long-term behaviour of ignition transformers with an acceptable amount of technical devices is documented in the following.

Normal values and standard deviations for pupil diameter and interpupillary distance in subjects aged 1 month to 19 years

Normal values of pupil diameters and interpupillary distances (PDs) were measured in a population of 1311 subjects (in 4294 visits) ranging from 1 month of age to slightly over 19 years of age. Subjects in this study were recruited from birth announcements in a local newspaper for a developmental vision project. Pupil sizes were measured photographically when the corneas were illuminated by 15.9 +/- 0.5 lux ambient illumination (i.e. under mesopic conditions). Interpupillary distance was measured with an interocular distance rule while the subject fixated an object at 0.66 m distance. These PD measurements were corrected for systematic measurement errors and to an infinite viewing distance using radii of ocular rotation based on age-dependent axial lengths. Means and S.D. were calculated for age, pupil diameter and PD for each 1-year group of male and female subjects. The second order regression equation for average pupil size as a function of age was determined: [males pupil diameter (in mm) = 5.83 +/- 0.181*age in years - 0053*age in years2, r2 = 0.897; female pupil diameter = 5.40 + 0.285*age in years - 0.0109*age in years2, r2 = 0.945]. The dierence between male and female pupil sizes (mean male - female = 0.13 mm) was marginally not significant (p < 0.054). The average corrected PDs as a function of age were found to approximate another second-order regression equation: (males PD = 43.36 + 1.663*age in years - 0.034*age in years2, r2 = 0.986; females PD = 41.76 + 1.891 *age in years - 0.052*age in years2, r2 = 0.986). Male PD was wider than female PD by an average of 1.58 mm (p < 0.0003). As expected, the results of this study were similar to a preliminary investigation conducted by Thunyalukul et al. [Invest. Ophthalmol. Vis. Sci. 37 (1996) S731] on a portion of the present data set, and also very similar to data from another study of comparable racial composition using a different measurement method [Pryor, Pediatrics 44 (1969) 973]. It was concluded that pupil diameter and PD increase more gradually than axial length of the eye in the first few years of life. The normal values and S.D. for both pupil size and PD determined in this study have important clinical implications as well as applications in the optical industry.

The predictive value of exhaled nitric oxide measurements in assessing changes in asthma control.

Exhaled nitric oxide (eNO) levels are increased in untreated or unstable asthma and measurements can be made easily. Our aim was to assess the usefulness of eNO for diagnosing and predicting loss of control (LOC) in asthma following steroid withdrawal. Comparisons were made against sputum eosinophils and airway hyperresponsiveness (AHR) to hypertonic saline (4.5%). Seventy-eight patients with mild/moderate asthma had their inhaled steroid therapy withdrawn until LOC occurred or for a maximum of 6 wk. Sixty (77.9%) developed LOC. There were highly significant correlations between the changes in eNO and symptoms (p < 0.0001), FEV(1) (p < 0.002), sputum eosinophils (p < 0.0002), and saline PD(15) (p < 0.0002), and there were significant differences between LOC and no LOC groups. Both single measurements and changes of eNO (10 ppb, 15 ppb, or an increase of > 60% over baseline) had positive predictive values that ranged from 80 to 90% for predicting and diagnosing LOC. These values were similar to those obtained using sputum eosinophils and saline PD(15) measurements. We conclude that eNO measurements are as useful as induced sputum analysis and AHR in assessing airway inflammation, with the advantage that they are easy to perform.