scholarly journals An Approach to a Clock Offsets Model for Real-Time PPP Time and Frequency Transfer During Data Discontinuity

2019 ◽  
Vol 9 (7) ◽  
pp. 1405 ◽  
Author(s):  
Weijin Qin ◽  
Yulong Ge ◽  
Pei Wei ◽  
Xuhai Yang
Keyword(s):  
Real Time ◽  
Real Data ◽  
Time Transfer ◽  
Short Term ◽  
Clock Model ◽  
Simulation Data ◽  
Term Stability ◽  
Adaptive Prediction ◽  
Receiver Clock ◽  
The Stability

To resolve the dilemma in any post-processing strategy, i.e., the difficulty of monitoring the real-time time and frequency signals in a timely manner, real-time GPS time and the frequency transfer have recently become trending topics. Unfortunately, data interruption occurs when conducting real-time time transfer, sometimes from unexpected reasons. In this study, to ensure the stability and precision of real-time time transfer, an adaptive prediction model and a between-epoch constraint receiver clock model are applied as the mathematic models. The purpose of prediction is to solve the ambiguity from re-convergence when the data reappear. Moreover, compared to the conventional method, the between-epoch constraint receiver clock model is employed in this study to consider the correlation of epoch-wise clock parameters to avoid wasting useful information. The simulation data and real data are compared to verify the performance of the new approach. The simulation data for 165 days are designed with random daily interruptions of 10, 30, 60 and 90 min. Real data from 12 days is captured from the incomplete data in routine observation records. Ignoring the simulation data and real data, the investigation of six stations shows that the results with the between-epoch constraint receiver clock model were smoother than those with a white noise model. With an adaptive prediction model and the between-epoch constraint receiver clock model, the simulation results illustrate that the average root mean squares (RMS) values of all the stations are significantly reduced, i.e., by 66.03% from 0.43 to 0.14 ns, by 64.91% from 0.44 to 0.15 ns, by 57.47% from 0.43 to 0.18 ns, and by 51.67% from 0.44 to 0.21 ns for the 10, 30, 60 and 90 min data interruptions, respectively. The stability of all the stations is improved by at least 50%. The improvement increases to 100% for short-term stability. The real results show that the stability of four links is boosted by at least 5%. The model proposed in this paper is more effective in producing short-term stability than long-term stability.

Real-Time GPS Clock Monitoring with IGS Ultra-Rapid Products

2011 ◽  
Vol 301-303 ◽  
pp. 1293-1298
Author(s):  
Youn Jeong Heo ◽  
Jeongho Cho ◽  
Moon Beom Heo
Keyword(s):  
Real Time ◽  
Carrier Phase ◽  
Time Transfer ◽  
Satellite Clock ◽  
Short Term ◽  
Transfer Method ◽  
The Stability

The objective of this study is to develop a real-time strategy that results in higher precision than any real-time solutions currently available for GPS satellite clock monitoring. A real-time time transfer methodology was employed for satellite clock monitoring, composed of carrier phase smoothed code measurements and IGS ultra-rapid products to obtain precise satellite positions. The performance of the time transfer method was assessed by comparison with the results based on the all-in-view method using the broadcasting ephemeredes. The results showed that the stability of satellite clock monitoring for a short-term period was improved by the proposed method.

Fabrication of Boron Compensated Hydrogenated Amorphous Silicon Films with Significantly Improved Stability Using Plasma Enhanced Chemical Vapor Deposition Technique

1995 ◽  
Vol 377 ◽  
Author(s):  
Mohan K. Bhan
Keyword(s):  
Chemical Vapor ◽  
Short Term ◽  
Term Stability ◽  
Long Term Stability ◽  
Vapor Deposition Technique ◽  
Improved Stability ◽  
Donor Acceptor ◽  
B Doping ◽  
The Stability

ABSTRACTWe have systematically investigated the effects of addition of sub-ppm levels of boron on the stability of a-Si:H films and p-i-n devices, deposited by PE-CVD technique. The films thus produced with appropriate amounts of boron, show a significant improvement in stability, when soaked under both AM 1.5 (short-term) as well as 10×sun (long-term) illumination conditions. The opto-electronic properties of the films are quite respectable It is concluded that boron compensates the native impurities by forming donor-acceptor pairs, which reduces the “fast” defects and hence the initial degradation of the films. It is also speculated that boron may also be improving the short-term stability, by reducing the recombination of light generated electrons and holes, by converting D° into D+ states. The long-term stability appears to get affected by hydrogen dilution which seems to reduce the amount of “slow” defects. As a result of B doping of i-layer, the initial conversion efficiency of the devices decreases. It is presumed that our devices may contain an enhanced level of boron impurity, than expected, making them as worse material and to degrade less.

Short-term stability of free metanephrines in plasma and whole blood

2020 ◽  
Vol 58 (5) ◽  
pp. 753-757 ◽  
Author(s):  
Elisa Danese ◽  
Martina Montagnana ◽  
Claudio Brentegani ◽  
Giuseppe Lippi
Keyword(s):  
Whole Blood ◽  
Repeated Measures ◽  
Sample Collection ◽  
Short Term ◽  
Total Change ◽  
Term Stability ◽  
Before And After ◽  
Liquid Chromatography Tandem Mass ◽  
The Mean ◽  
The Stability

AbstractBackgroundAnalysis of plasma metanephrine (MN) and normetanephrine (NMN) with liquid chromatography tandem mass spectrometry (LC-MS/MS) is the gold standard for the screening of pheochromocytomas and paragangliomas (PPGLs). As scarce information is available on the stability of MNs in diagnostic samples, this study was aimed at analyzing the short-term stability of plasma free MNs in whole blood and plasma, using LC-MS/MS.MethodsThe stability of plasma MNs was evaluated after sample collection at 1, 2 and 3 h in whole blood, and at 2, 4 and 6 h in centrifuged samples. Both studies were performed while maintaining the samples at room temperature (RT) and at 4 °C. The ClinMass Complete Kit (Recipe, Munchen, Germany) was used for measuring MNs with LC-MS/MS (Nexera X2 UHPLC-4500MD Sciex). Differences from the baseline (T0) were assessed using repeated measures one-way ANOVA, Students’ paired t-test and a comparison of the mean percentage changes with the total change limit (TCL).ResultsStatistically significant differences from T0 were found for both MNs (p < 0.001) in whole blood stored at RT, and for NMN (p = 0.028) but not MN (p = 0.220) at 4 °C. The mean difference exceeded the TCL after 1 h and 3 h at RT for MN, and after 1 h at RT for NMN. Statistically significant differences from T0 were only observed in the plasma samples for NMN at RT (p = 0.012), but the variation was within the TCL.ConclusionsMN and NMN displayed different patterns of stability before and after centrifugation. Even short-time storage at RT in whole blood should hence be avoided.

scholarly journals Quantification of Cefepime, Meropenem, Piperacillin, and Tazobactam in Human Plasma Using a Sensitive and Robust Liquid Chromatography-Tandem Mass Spectrometry Method, Part 2: Stability Evaluation

2018 ◽  
Vol 62 (9) ◽  
Author(s):  
Ronilda D'Cunha ◽  
Thanh Bach ◽  
Beth Ann Young ◽  
Peizhi Li ◽  
Demet Nalbant ◽  
...  
Keyword(s):  
Human Plasma ◽  
Whole Blood ◽  
Room Temperature ◽  
Solution Stability ◽  
Short Term ◽  
Term Stability ◽  
Degradation Rates ◽  
Liquid Chromatography Tandem Mass ◽  
The Stability ◽  
Stability Results

ABSTRACT Although the stability of β-lactam antibiotics is a known issue, none of the previously reported bioanalytical methods had an adequate evaluation of the stability of these drugs. In the current study, the stability of cefepime, meropenem, piperacillin, and tazobactam under various conditions was comprehensively evaluated. The evaluated parameters included stock solution stability, short-term stability, long-term stability, freeze-thaw stability, processed sample stability, and whole-blood stability. When stored at −20°C, the stock solution of meropenem in methanol was stable for up to 3 weeks, and the stock solutions of cefepime, piperacillin, and tazobactam were stable for up to 6 weeks. All four antibiotics were stable in human plasma for up to 3 months when stored at −80°C and were stable in whole blood for up to 4 h at room temperature. Short-term stability results indicated that all four β-lactams were stable at room temperature for 2 h, but substantial degradation was observed when the plasma samples were stored at room temperature for 24 h, with the degradation rates for cefepime, meropenem, piperacillin, and tazobactam being 30.1%, 75.6%, 49.0%, and 37.7%, respectively. Because the stability information is method independent, our stability results can be used as a reference by other research groups that work with these antibiotics.

Time Synchronization Method Based on Real-Time Precise Point Positioning

2020 ◽  
Author(s):  
Daqian Lyu ◽  
Tianbao Dong ◽  
Fangling Zeng ◽  
Xiaofeng Ouyang
Keyword(s):  
Real Time ◽  
Time Scale ◽  
Precise Point Positioning ◽  
Time Synchronization ◽  
Synchronization Error ◽  
Time Transfer ◽  
The Real ◽  
Local Clock ◽  
Receiver Clock ◽  
Clock Offset

&lt;p&gt;Precise point positioning (PPP) technique is an effective tool for time and frequency applications. Using phase/code observations and precise products, the PPP time transfer allows an accuracy of sub-nanoseconds within a latency of several days. Although the PPP time transfer is usually implemented in the post-processing mode, using the real-time PPP (RT-PPP) technique for time transfer with the shorter latency remains attractive to time community. In 2012, the IGS (International GNSS Service) launched an open-access real-time service (RTS) project, broadcasting satellite orbit and clock corrections on the Internet, which enables PPP time transfer in the real-time mode. In this contribution, we apply the RT-PPP for high-precision time transfer and synchronization. The GNSS receiver is required to be equipped with an atomic clock as the external local clock. We use the RT-PPP technique to compute the receiver clock offset with respective to the GNSS time scale. On the basis of clock offsets, we steer the local clock by frequency adjustment method. In this way, all the local clocks are synchronized to the GNSS time scale, making local clocks synchronized with each other.&lt;/p&gt;&lt;p&gt;The time scales of the RTS products are evaluated at first. Six kinds of the RTS products (IGS01, CLK10, CLK53, CLK80 and CLK93) on DOY220-247, 2019 are pre-saved to compute the receiver clock offsets. The clock offset with respect to the GPST (GPS Time) obtained from the IGS final product is applied as the reference. The standard deviations (STDs) of the clock offsets with respect to the reference are 0.63, 1.76, 0.28, 0.27 and 1.28 ns for IGS01, CLK10, CLK53, CLK80 and CLK93, respectively.&lt;/p&gt;&lt;p&gt;Finally, we set up a hardware system to examine the validity of our time synchronization method. The baseline of the time synchronization experiment is about 5 m. The synchronization error of the 1 PPS outputs is precisely measured by the frequency counter. The STD of the 4-days results is about 0.48 ns. The peak-to-peak value of the synchronization error is about 2.5 ns.&lt;/p&gt;

Analytical Features of the New Red Blood Cell and White Blood Cell LH750 Research Population Data.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3841-3841
Author(s):  
Josep Piqueras ◽  
Maria J. Capel ◽  
Jose J. Duran ◽  
Pedro J. Jimenez
Keyword(s):  
Blood Cell ◽  
Population Data ◽  
Short Term ◽  
Term Stability ◽  
Normal Individuals ◽  
Blood Drawing ◽  
Research Population ◽  
The Mean ◽  
The Stability

Abstract Recently, a new set of parameters produced by the Beckman-Coulter’s GEN’S, LH500, LH750 and the latest LH780 automated blood counters, derived from leukocyte and red cell’s morphological data by means of the VCS technology are available and can be printed as research data together with the leukocyte differential and reticulocyte analysis. With the use of these Research Population Data (RPD) parameters several recent publications have shown their usefulness for the diagnosis of malaria (Fourcade et al), sepsis (Chaves ), apoptosis detection (Lab hem 2005) and the diagnosis and differentiation of lymphoptoliferative disorders (Silva M et al) In order to evaluate the analytical behaviour of these newly described red blood cell and leukocyte morphological parameters in routine bood samples and in the Beckman-Coulter’s calibration and control 5C, we conducted a study to evaluate the paramters’ precision and performance during short and long term sample’s storage: Precision: 10 samples from normal individuals were analyzed 10 times and the CV for each parameter was calculated Short term stability stability at 4C and 22C: 5 normal samples were evaluated from the time of blood drawing until 5 hours later, both at room temperature (22C) and at 4 C Long term stability at 4C: 15 normal samples were evaluated at various times after blood drawing, from 4 hours (which was found to be the best time for sample analysis in the short term stability study, above) up to 77 hours after blood withdrawal. Control and Calibration with 5C: We evaluated the performance of the research parameters in the 5C by running the same batch of 5C control in 5 different counters from 4 different centers, comparing the results with those from 5 normal individuals Stability in a period of time: We have evaluated every week during two months 15 normal samples, recording the temperature and the avergae of all RPD values. RESULTS Precission: The CV% for the Mean Volume, Conductivity and Scatter of the different leukocyte types was always less than 1%, with an average of 0,6%. The CV% for the Standard Deviation of Volume, Conductivity and Scatter varied between 2.45% and 7.7%, wit an average of 4.9%. The CV% of any SD always being higher than the primary parameter. Short term stability: We observed no significant differences between samples kept at 4C and 22C during the first 5 hours after blood drawing. During the first two hours, however, minor fluctuations in results occurred, always <5%, being preferable to test the samples after blood stabilization, between 2 and 5 hours after withdrawal. Long term stability: The stability of the research parameters after 9 hours is best when the samples are kept at 4C, but the differences are not clinically significant up to 17 hours and, for some parameters, up to 24 hours after blood drawing. The comparison of the RPD research parameters from normal samples and from the Beckman’s 5C control showed good correlation in the different counters and the different centers. When the results from the 5C were higher or lower, the results from the normal samples were concordantly higher or lower respectively, The correlation coefficient was 0.98 for the Mean Volume and 0.92 for the Mean Conductivity The Stability of RPD values was acceptable during the period evaluated (2 m.)with changes lower than 3%. CONCLUSIONS: The results of the present study show that from the analytical stand point, precission, stability and possibility of calibration, these Research Population data are equivalent to those of other laboratory tests performed by modern instruments.

Investigation of Titanium in Metamict Nb-Ta-Ti Oxides Using the Extended X-Ray Absorption Fine Structure Technique

1981 ◽  
Vol 11 ◽  
Author(s):  
R. B. Greegor ◽  
F. W. Lytle ◽  
R. C. Ewing ◽  
R. F. Haaker
Keyword(s):  
Radiation Effects ◽  
Short Term ◽  
Term Stability ◽  
Long Term Stability ◽  
Ti Oxides ◽  
Considerable Controversy ◽  
Simple Phase ◽  
The Stability ◽  
X Ray Absorption

Recent proposals have suggested that radioactive wastes can be isolated 1 as dilute solid solutions in a crystalline, titanate assemblage. One titanate assemblage, SYNROC, consists of zirconolite (CaZrTi207), perovskite (CaTiO3) and "hollandite" (BaAl2Ti6016) with additional accessory phases. There are two major problems in the evaluation of the long term stability of any crystalline wasteform such as SYNROC: 1) it is difficult to assess the long term stability of materials from short term laboratory experiments that are not necessarily valid simulations of complex geochemical processes, and 2)the corresponding titanate minerals are uncommon, making it difficult to study long term alteration and radiation effects on a significant number of specimens from different localities and geologic environments. There has even been considerable controversy concerning the stability of the reasonably common and simple phase, perovskite (CaTiO3)

Framework for real-time short-term stability assessment of power systems using PMU measurements

2019 ◽  
Vol 13 (15) ◽  
pp. 3433-3442 ◽  
Author(s):  
Arash Safavizadeh ◽  
Meysam Kordi ◽  
Fariborz Eghtedarnia ◽  
Roozbeh Torkzadeh ◽  
Hesamoddin Marzooghi
Keyword(s):  
Power Systems ◽  
Real Time ◽  
Stability Assessment ◽  
Short Term ◽  
Term Stability

Remarks on the stability of temporary cuts

1990 ◽  
Vol 27 (5) ◽  
pp. 687-692 ◽  
Author(s):  
S. Leroueil ◽  
P. La Rochelle ◽  
F. Tavenas ◽  
M. Roy
Keyword(s):  
Undrained Shear Strength ◽  
Short Term ◽  
Overconsolidation Ratio ◽  
Term Stability ◽  
Long Term Stability ◽  
Liquidity Index ◽  
The Stability ◽  
Insight Into ◽  
Undrained Shear

A re-analysis of the observations and data related to the stability of excavations in clays gives a new insight into the problem. It is shown that for clays with a liquidity index greater than 0.4, the short-term stability can be estimated on the basis of the undrained shear strength without applying any correction factor; it is also shown that the long-term stability is lower than the short-term stability by an amount that depends on the overconsolidation ratio of the clay. Finally, experience proving that pore-pressure equilibration is highly variable and difficult to predict, it is recommended to systematically instrument excavations with piezometers. Key words: clay, short-term stability, long-term stability, excavations, pore pressures, overconsolidation ratio.

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