Delay Time Measurement and Comparison of Protection Strategies with One-Link Failed Domestic Optical Fiber Networks in Taiwan

In this paper, we study the protection strategies of domestic optical fiber networks in Taiwan. Delay time experiment of two one-link failed cases are also reported and compared. We can get best protection strategy and bypass the optical transmission signal at shortest delay time.

Applying nonlinear filtering in reverberation time measurement under strong background noise

Nonlinear filtering of impulse response obtained by M-sequence correlation method under strong background noise is presented. The research shows that the new method works very efficiently without the need to cut off impulse response data. Even if the ratio of signal to noise is below -15 dB, the same decay curve ranges can still be obtained as when S/N > 40

Integrated method for measuring distance and time difference between small satellites

The advancement of small satellites is promoting the development of distributed satellite systems,and for the latter,it is essential to coordinate the spatial and temporal relations between mutually visible satellites.By now,dual one-way ranging(DOWR)and two-way time transfer(TWTT)are generally integrated in the same software and hardware system to meet the limitations of small satellites in terms of size,weight and power(SWaP)consumption.However,studies show that pseudo-noise regenerative ranging(PNRR)performs better than DOWR if some advanced implementation technologies are employed.Besides,PNRR has no requirement on time synchronization.To apply PNRR to small satellites,and meanwhile,meet the demand for time difference measurement,we propose the round-way time difference measurement,which can be combined with PNRR to form a new integrated system without exceeding the limits of SWaP.The new integrated system can provide distributed small satellite systems with on-orbit high-accuracy and high-precision distance measurement and time difference measurement in real time.Experimental results show that the precision of ranging is about 1.94 cm,and that of time difference measurement is about 78.4 ps,at the signal to noise ratio of 80 dBHz.

Energy and flux measurements of laser-induced silver plasma ions by using Faraday cup

Silver(Ag)plasma has been generated by employing Nd:YAG laser(532 nm,6 ns)laser irradiation.The energy and flux of ions have been evaluated by using Faraday cup(FC)using time of flight(TOF)measurements.The dual peak signals of fast and slow Ag plasma ions have been identified.Both energy and flux of fast and slow ions tend to increase with increasing irradiance from 7 GW cm-2 to 17.9 GW cm-2 at all distances of FC from the target surface.Similarly a decreasing trend of energies and flux of ions has been observed with increasing distance of FC from the target.The maximum value of flux of the fast component is21.2×10^(10) cm^(-2),whereas for slow ions the maximum energy and flux values are 8.8 keV,8.2×10^(10) cm^(-2) respectively.For the analysis of plume expansion dynamics,the angular distribution of ion flux measurement has also been performed.The overall analysis of both spatial and angular distributions of Ag ions revealed that the maximum flux of Ag plasma ions has been observed at an optimal angle of~15°.In order to confirm the ion acceleration by ambipolar field,the self-generated electric field(SGEF)measurements have also been performed by electric probe;these SGEF measurements tend to increase by increasing laser irradiance.The maximum value of 232 V m^(-1) has been obtained at a maximum laser irradiance of 17.9 GW cm^(-2).

Assessing the Impact of the Lead/Lag Times on the Project Duration Estimates in Highway Construction

The literature mentions multiple factors that can affect the accuracy of estimating the project duration in highway construction,such as weather,location,and soil conditions.However,there are other factors that have not been explored,yet they can have significant impact on the accuracy of the project time estimate.Recently,TxDOT raised a concern regarding the importance of the proper estimating of the lead/lag times in project schedules.These lead/lag times are often determined based on the engineer’s experience.However,inaccurate estimates of the lead/lag time can result in unrealistic project durations.In order to investigate this claim,the study utilizes four time sensitivity measures(TSM),namely the Criticality Index(CI),Significance Index(SI),Cruciality Index(CRI),and the Schedule Sensitivity Index(SSI)to statistically analyze and draw conclusions regarding the impact of the lead/lag time estimates on the total duration in highway projects.An Excel-based scheduling software was developed with Monte Carlo simulation capabilities to calculate these TSM.The results from this paper show that the variability of some lead/lag times can significantly impact the accuracy of the estimated total project duration.It was concluded that the current practices used for estimating the lead/lag times are insufficient.As such,it is recommended to utilize more robust methods,such as the time sensitivity measures,to accurately estimate the lead/lad times in the projects scheduled.

Data-driven Detection and Identification of Line Parameters with PMU and Unsynchronized SCADA Measurements in Distribution Grids

Line parameters play an important role in the control and management of distribution systems.Currently,phasor measurement unit(PMU)systems and supervisory control and data acquisition(SCADA)systems coexist in distribution systems.Unfortunately,SCADA and PMU measurements usually do not match each other,resulting in inaccurate detection and identification of line parameters based on measurements.To solve this problem,a data-driven method is proposed.SCADA measurements are taken as samples and PMU measurements as the population.A probability parameter identification index(PPII)is derived to detect the whole line parameter based on the probability density function(PDF)parameters of the measurements.For parameter identification,a power-loss PDF with the PMU time stamps and a power-loss chronological PDF are derived via kernel density estimation(KDE)and a conditional PDF.Then,the power-loss samples with the PMU time stamps and chronological correlations are generated by the two PDFs of the power loss via the Metropolis-Hastings(MH)algorithm.Finally,using the power-loss samples and PMU current measurements,the line parameters are identified using the total least squares(TLS)algorithm.Hardware simulations demonstrate the effectiveness of the proposed method for distribution network line parameter detection and identification.

Prototype of the readout electronics for the RICH PID detector in the STCF

The ring imaging Cherenkov(RICH) detector for particle identification(PID) is being evaluated for the future super tau-charm facility(STCF) complex. In this work, the prototype readout electronics for the RICH PID detector is designed. The prototype RICH PID detector is based on a thick gas electron multiplier combined with a micromegas detector for Cherenkov light detection. Considering that there will be a large number(~ 690,000) of detector channels in future RICH detector, the readout electronics faces many challenges to precisely measuring time and charge information, such as reducing the noise,increasing density, and improving precision. The requirements of the readout electronics are explored, the downselection of the ASICs is made and thus a prototype readout electronics is designed and implemented. Tests are also conducted to evaluate the performance of the prototype readout electronics, and the results indicate that the time resolution is better than ~ 1 ns(RMS) when the input charge is greater than ~ 12 fC based on the APV25chip, while the time resolution is better than ~ 1 ns(RMS) at an input charge of over ~ 48 fC based on the AGET and STCF ASIC chips, and the equivalent noise charge is better than ~ 0.5 fC(RMS) @ 20 pF based on the three ASICs. The test results indicate that the prototype readout electronics design meets the requirement of the future RICH PID detector and thus provides a reference for future engineering.

Influence of Precipitation on the Determination of Proper Time for Soil Resistivity Measurement

In order to obtain reliable and effective upland soil resistivity measurements,it is necessary to know how much time after the rain stops is required before making soil resistivity observations so that the influence of precipitation on the measurements can be eliminated.Based on the soil resistivity monitoring data at different depths obtained from the soil conductance automatic monitoring system using the triple-electrode method,and the precipitation data from the synchronous and automatic observing system in Hechuan County of Chongqing,this paper analyzed the effect of rain on the determination of upland soil resistivity measurement time.The results showed that the required interval time between the measurement and the termination of rain should be as follows:if the rainfall was less than 0.1 mm,the interval time was zero;the interval time was 24 h if the precipitation time was less than 1 h or the rainfall was 0.1-2.0 mm;the interval time was 72 h if the precipitation time was 2-10 h or the rainfall was within 2.1-5.0 mm;and the interval time of 72-232 h was observed when the precipitation time was 10-25 h or longer or the rainfall was 5.0-10.1 mm or larger.Relevant observations showed that the above conclusions were on the whole valid for different soil depths.On the other hand,the results indicated that the maximum variance ratio for the influence of precipitation on resistivity measurement was about 28.9%,and the average variance was about 3.9%.Moreover,a preliminary analysis also showed that the precipitation process time might play a more crucial role in the resistivity recovery time than the precipitation amount.It is also found that it is practically better to use the rank correlation method than the numerical correlation analysis method to determine the time break between the stop of rain and the time to carry out the soil resistivity measurement.

Success and Incoherence of Orthodox Quantum Mechanics

Orthodox quantum mechanics is a highly successful theory despite its serious conceptual flaws. It renounces realism, implies a kind of action-at-a-distance and is incompatible with determinism. Orthodox quantum mechanics states that Schr&oumldinger’s equation (a deterministic law) governs spontaneous processes while measurement processes are ruled by probability laws. It is well established that time dependent perturbation theory must be used for solving problems involving time. In order to account for spontaneous processes, this last theory makes use of laws valid only when measurements are performed. This incoherence seems absent from the literature.

Precise time scales and navigation systems:mutual benefits of timekeeping and positioning

The relationship and the mutual benefits of timekeeping and Global Navigation Satellite Systems(GNSS)are reviewed,showing how each field has been enriched and will continue to progress,based on the progress of the other field.The role of GNSSs in the calculation of Coordinated Universal Time(UTC),as well as the capacity of GNSSs to provide UTC time dissemination services are described,leading now to a time transfer accuracy of the order of 1-2 ns.In addition,the fundamental role of atomic clocks in the GNSS positioning is illustrated.The paper presents a review of the current use of GNSS in the international timekeeping system,as well as illustrating the role of GNSS in disseminating time,and use the time and frequency metrology as fundamentals in the navigation service.

Partial Discharge Measurement and Analysis in High Voltage IGBT Modules Under DC Voltage

Insulation performance of high voltage IGBT modules is one of the key attributes in power system applications.However,the existing standards of IGBT devices and research on the evaluation of insulation performance of high voltage IGBT modules are insufficient;for example,partial discharge resistance under DC voltage blocking condition is not considered.In this paper,a new test was proposed to allow the measurement of partial discharges in all the components of IGBT modules under DC voltage.The topology of the measuring circuit is arranged in the polarity discrimination way to exclude the interference,and the voltage and discharge current waveforms during the partial discharge process are measured by the wideband time domain measurement technique.According to the proposed test,the discharge phenomenon of the IGBT modules below the rating voltage were detected.A comprehensive waveform analysis on the voltage and discharge current was performed,and the influence of the applied voltage on the waveform parameters was obtained.The waveform parameters are influenced by the applied voltage and insulation structure,which enables the discrimination of the causes of the observed partial discharge in the IGBT module under DC voltage by the waveform analysis technique.Based on the waveform analysis technique,the types and causes of the observed partial discharges were discussed and inferred,and the correctness of the inference was further verified by observation.The proposed test and waveform analysis technique provide the possibility to evaluate and distinguish partial discharges in the high voltage IGBT module under DC voltage,which may be helpful to insulation performance evaluation and insulation defect diagnosis in high voltage IGBT module.

Bootstrap generated confidence interval for time averaged measure

In the simulation output analysis,there are some measures that should be calculated by time average concept such as the mean queue length.Especially,the confidence interval of those measures might be required for statistical analysis.In this situation,the traditional method that utilizes the central limit theorem(CLT)is inapplicable if the output data set has autocorrelation structure.The bootstrap is one of the most suitable methods which can reflect the autocorrelated phenomena in statistical analysis.Therefore,the confidence interval for a time averaged measure having autocorrelation structure can also be calculated by the bootstrap methods.This study introduces the method that constructs these confidence intervals applying the bootstraps.The bootstraps proposed are the threshold bootstrap(TB),the moving block bootstrap(MBB)and stationary bootstrap(SB).Finally,some numerical examples will be provided for verification.