scholarly journals Preliminary Research on a Comparison and Evaluation of FY-4A LMI and ADTD Data through a Moving Amplification Matching Algorithm

2020 ◽  
Vol 13 (1) ◽  
pp. 11
Author(s):  
Pengfei Li ◽  
Guofu Zhai ◽  
Wenjing Pang ◽  
Wen Hui ◽  
Wenjuan Zhang ◽  
...  
Keyword(s):  
Detection Efficiency ◽  
Spherical Surface ◽  
Operation Time ◽  
Mean Value ◽  
China Meteorological Administration ◽  
Matching Algorithm ◽  
Lightning Detection ◽  
Spatial Differences ◽  
System Data ◽  
Spatial Threshold

In this study, a new moving amplification matching algorithm was proposed, and then the temporal and spatial differences and correlation were analysed and evaluated by comparing the FengYun-4A Lightning Mapping Imager (FY-4A LMI) data and the China Meteorological Administration Lightning Detection Network Advanced TOA and Direction (CMA-LDN ADTD) system data of southwest China in July 2018. The results are as follows. Firstly, the new moving amplification matching algorithm could effectively reduce the number of invalid operations and save the operation time in comparison to the conventional ergodic algorithms. Secondly, LMI has less detection efficiency during the daytime, using ADTD as a reference. The lightning number detected by ADTD increased from 5:00 AM UTC (13:00 PM BJT, Beijing Time) and almost lasted for a whole day. Thirdly, the trends of lightning data change of LMI and ADTD were the same as the whole. The average daily lightning matching rate of the LMI in July was 63.23%. The average hourly lightning matching rate of the LMI in July was 75.08%. Lastly, the mean value of the spherical surface distance in the matched array was 35.49 km, and roughly 80% of the matched distance was within 57 km, indicating that the spatial threshold limit was relatively stable. The correlation between LMI lightning radiation intensity and ADTD lighting current intensity was low.

scholarly journals Evaluating Strong Currents at a Fairway in the Finnish Archipelago Sea

2018 ◽  
Vol 6 (4) ◽  
pp. 122 ◽  
Author(s):  
Hedi Kanarik ◽  
Laura Tuomi ◽  
Pekka Alenius ◽  
Mikko Lensu ◽  
Elina Miettunen ◽  
...  
Keyword(s):  
Cross Section ◽  
Acoustic Doppler Current Profiler ◽  
Mean Value ◽  
Automatic Identification ◽  
Identification System ◽  
Marine Traffic ◽  
Current Profiler ◽  
System Data ◽  
The Cross ◽  
Oceanographic Conditions

Safe navigation in complex archipelagos requires knowledge and understanding of oceanographic conditions in the fairways. We have studied oceanographic conditions and their relation to weather in a crossing in the Finnish archipelago, which is known to have events when strong currents affect marine traffic. Our main dataset is ADCP (Acoustic Doppler Current Profiler) current measurements, done in the cross section of five months in 2013. We found that the local currents flow mainly to two directions, either to north-northeast (NNE) or to south-southwest (SSW), which is nearly perpendicular to the deepest fairway in the area. The mean value of the currents in the surface layer was 0.087 ms - 1 , but during the high wind situations, the current speed rose over 0.4 ms - 1 . These strong currents were also shown, according to AIS (Automatic Identification System) data, to cause drift of the vessels passing the cross section, though the effect of wind and current to the ship may sometimes be hard to separate. We studied whether the strong currents could be predicted from routine observations of wind and sea level available in the area, and we found that prediction of these currents is possible to some extent. We also found that winds of over 10 ms - 1 blowing from NW (300 ∘ –350 ∘ ) and SE (135 ∘ –180 ∘ ) generated strong currents of over 0.2 ms - 1 , whereas most commonly measured winds from SW (190 ∘ –275 ∘ ) did not generate currents even with winds as high as 15 ms - 1 .

CONTAMINATION DEPTH OF 137CS IN CONCRETE STRUCTURES

2019 ◽  
Vol 186 (2-3) ◽  
pp. 301-305
Author(s):  
Martin Listjak ◽  
Alojz Slaninka ◽  
Vladimír Nečas
Keyword(s):  
Relative Error ◽  
Detection Efficiency ◽  
Statistical Error ◽  
Mean Value ◽  
Distribution Profile ◽  
Relaxation Length ◽  
Peak Areas ◽  
Nondestructive Estimation ◽  
Crucial Assumption

Abstract Uncertainty analysis for nondestructive estimation of contamination depth is presented. The contamination depth was determined using the peak-to-peak method as an in-situ measurement in which gamma spectra were measured by an HPGe detector. Since exponential activity distribution is a crucial assumption of this method, the distribution profile was confirmed by laboratory tests of core drill samples. The main parameter influencing uncertainty of contamination depth is uncertainty of relaxation length. The uncertainty is composed for statistical error represented by the ratio of net peak areas and systematic error given detection efficiency of measurement setup. Systematic relative error was evaluated to be 7.45%. Statistical relative error was evaluated to 9.97% for the proposed optimum net peak area. Variability of relaxation length was identified to be very low with mean value 2 mm with standard deviation 0.73 mm. For fixed relaxation length, it should be possible to estimate contamination depth by nonspectrometric devices.

Performance evaluation of the U.S. National Lightning Detection Network in eastern New York: 1. Detection efficiency

1998 ◽  
Vol 103 (D8) ◽  
pp. 9045-9055 ◽  
Author(s):  
Vincent P. Idone ◽  
Daniel A. Davis ◽  
Paul K. Moore ◽  
Yan Wang ◽  
Ronald W. Henderson ◽  
...  
Keyword(s):  
New York ◽  
Performance Evaluation ◽  
Detection Efficiency ◽  
Lightning Detection ◽  
The U.S

scholarly journals A performance assessment of the World Wide Lightning Location Network (WWLLN) via comparison with the Canadian Lightning Detection Network (CLDN)

2010 ◽  
Vol 3 (2) ◽  
pp. 1861-1887 ◽  
Author(s):  
D. Abreu ◽  
D. Chandan ◽  
R. H. Holzworth ◽  
K. Strong
Keyword(s):  
Standard Deviation ◽  
World Wide ◽  
Detection Efficiency ◽  
Low Frequency ◽  
High Peak ◽  
Peak Current ◽  
Lightning Detection ◽  
The World ◽  
The Mean ◽  
The Difference

Abstract. The World Wide Lightning Location Network (WWLLN) uses globally-distributed Very Low Frequency (VLF) receivers in order to observe lightning around the globe. Its objective is to locate as many global strokes as possible, with high temporal and spatial (<10 km) accuracy. Since detection is done in the VLF range, signals from high peak current lightning strokes are able to propagate up to ~104 km before being detected by the WWLLN sensors, allowing for receiving stations to be sparsely spaced. Through a comparison with measurements made by the Canadian Lightning Detection Network (CLDN) between May and August 2008 over a 4° latitude by 4° longitude region centered on Toronto, Canada, this study found that WWLLN detection was most sensitive to high peak current lightning strokes. Events were considered shared between the two networks if they fell within 0.5 ms of each other. Using this criterion, 19 128 WWLLN strokes (analyzed using the Stroke_B algorithm) were shared with CLDN lightning strokes, producing a detection efficiency of 2.8%. The peak current threshold for WWLLN detection is found to be ~20 kA, with the detection efficiency increasing to ~70% at peak currents of ±120 kA. The detection efficiency is seen to have a clear diurnal dependence, with a higher detection efficiency at local midnight than at local noon; this is attributed to the difference in the thickness of the ionospheric D-region between night and day. The mean time difference (WWLLN – CLDN) between shared events was −6.44 μs with a standard deviation of 35 μs, and the mean absolute location accuracy was 7.24 km with a standard deviation of 6.34 km. These results are generally consistent with previous comparison studies of the WWLLN with other regional networks around the world. Additional receiver stations are continuously being added to the network, acting to improve this detection efficiency.

scholarly journals Evaluation of the performance characteristics of the North American Lightning Detection Network based on extensive CN Tower lightning data

2021 ◽  
Author(s):  
Savdulla Kazazi
Keyword(s):  
North American ◽  
Detection Efficiency ◽  
Performance Characteristics ◽  
Enhancement Effect ◽  
Return Stroke ◽  
Location Accuracy ◽  
Peak Current ◽  
The North ◽  
Current Estimation ◽  
Lightning Detection

The North American Lightning Detection Network (NALDN) has been providing lightning data since 1998. Important applications, such as detection of lightning-caused forest fires, power line fault locations and aviation safety procedures, have triggered a number of hardware and software upgrades for improving the network performance characteristics, including its detection efficiency and location accuracy. The NALDN performance characteristics are here evaluated based on the lightning currents measured at the CN Tower during three major storms (2005, 2011 and 2014). Each of these three storms followed one of the network’s substantial upgrades that took place in 2003-2004, 2010-2011 and 2013-2014. The major contribution of this extensive investigation is the determination of the network’s performance characteristics following each of the three major upgrades, which is expected to lead to additional upgrades. Since 1990, the lightning current derivatives of return strokes have been measured at the CN Tower. Its 553-m height has allowed the recording of the current derivative signals of many hundreds of return strokes. Also, imaging systems have been used to record trajectories of flashes to the tower. The evaluated performance characteristics of the network include return-stroke detection efficiency, location accuracy, and return-stroke polarity and peak current estimation. The 2013 NALDN deployment of LS7002 digital sensors with enhanced embedded software has substantially improved the sensitivity of the sensors leading to a greater return-stroke detection efficiency. Furthermore, the 2014 total lightning processor (TLP100) –designed with new algorithm - provides smaller time-of-arrival errors, leading to better location accuracy. Based on the 2014 storm evaluation, the numbers and polarities of NALDN-detected return strokes were perfectly matched with those recorded at the tower. Furthermore, based on the 2014 storm evaluation, the NALDN is found, as expected, to overestimate the current peak measured at the tower by a factor of 3.89, which is due to the field enhancement effect resulting from the high-speed of propagation of the current within the tall tower. The presented analysis shows that the latest NALDN upgrades (2013-2014), following the 2003-2004 and 2010-2011 upgrades, have substantially improved the NALDN performance characteristics, especially in terms of stroke-detection efficiency and location accuracy. Keywords: Tall-structure lightning; lightning detection; detection efficiency; location accuracy; peak current estimation.

scholarly journals Recent History of Upgrades to the U.S. National Lightning Detection Network

2020 ◽  
Author(s):  
Martin J. Murphy ◽  
John A. Cramer ◽  
Ryan K. Said
Keyword(s):  
Detection Efficiency ◽  
Processing System ◽  
Sensor Data ◽  
Recent History ◽  
Central Processor ◽  
Central Processing ◽  
Lightning Detection ◽  
History Of ◽  
Location Algorithm ◽  
The U.S

AbstractThe U.S. National Lightning Detection Network (NLDN) underwent a complete sensor upgrade in 2013 followed by a central processor upgrade in 2015. These upgrades produced about a factor-of-five improvement in the detection efficiency of cloud lightning flashes and about one additional cloud pulse geo-located per flash. However, they also re-aggravated a historical problem with the tendency to misclassify a population of low-current positive discharges as cloud-to-ground strokes when, in fact, most are probably cloud pulses. Furthermore, less than 0.1% of events were poorly geo-located because the contributing sensor data were either improperly associated or simply under-utilized by the geo-location algorithm. To address these issues, Vaisala developed additional improvements to the central processing system, which became operational on November 7, 2018. This paper describes updates to the NLDN between 2013-2018 and then focuses on the effects of classification algorithm changes and a simple means to normalize classification across upgrades.

scholarly journals Adsorption capacity of GAC pilot filter-adsorber and postfilter- adsorber for individual THMs from drinking water, Athens

2013 ◽  
Vol 13 (1) ◽  
pp. 50-58
Keyword(s):  
Drinking Water ◽  
Adsorption Capacity ◽  
Operation Time ◽  
Freundlich Isotherm ◽  
Physicochemical Characteristics ◽  
Mean Value ◽  
Laboratory Animals ◽  
Residual Chlorine ◽  
Uniformity Coefficient ◽  
Regular Sampling

Trihalomethanes are a major class of chlorination by-products in drinking water. They are formed when chlorine reacts with bromide (Br-) and natural organic matter (NOM) in source waters. Toxicology studies have shown all THMs to be carcinogenic or to cause adverse reproductive or developmental effects in laboratory animals. THMs are small volatile molecules, which are hydrophobic, non biodegradable and adsorbable on granular activated carbon (GAC). The objective of this pilot study is to evaluate the adsorption capacity for individual THMs of a GAC filter-adsorber (A) and a GAC postfilter-adsorber (B), both fed with chlorinated natural water. For this purpose, a GAC pilot plant was operated as a filter-adsorber and a postfilter-adsorber in Galatsi WTP, Athens (GTP) until the removal of individual THMs by GAC was eliminated (breakthrough). Regular sampling was performed during operation and the parameters measured were: THMs, DOC, free residual chlorine, bromide, turbidity, pH and temperature. From the experimental data, GAC bed life, GAC usage rate, GAC loading and operation time to breakthrough were calculated for most THMs. TBM was almost not detected. Some desorption of THMs, especially TCM and BDCM, was noticed during the operation of both adsorbers. Near breakthrough for THMs, equilibrium between adsorbed and dissolved THMs was considered to have been established. The GAC equilibrium loading of individual THMs was assumed to depend on the mean value of their influent concentration, which was not constant. By correlating the equilibrium data by linear regression to conform to the Freundlich isotherm, the Freundlich constants 1/n and k were determined for each of THMs. They are related to the physicochemical characteristics and background organics of water and the specific GAC used. The strength of the adsorption bond and the GAC capacity was higher for DBCM, lower for BDCM and even lower for TCM for both adsorbers. In addition, the GAC(B) capacity for BDCM and DBCM was higher than that of GAC(A), probably due to larger surface area and surface chemistry of GAC(B). Also, the lower particle size and the higher uniformity coefficient of GAC(B), along with the lower flow rate may have attributed to that by enhancing GAC equilibration. However, TCM was less adsorbed by GAC(B), probably due to the stronger competition effect by BDCM and DBCM, being in much higher mean influent concentration. The DOC content of influent water seems also to reduce significantly the adsorption of THMs (especially of TCM), as the comparison of our results with the isotherm results with distilleddeionized water by other researchers showed.

scholarly journals A performance analysis of the North American Lightning Detection Network using CN Tower lightning data

2021 ◽  
Author(s):  
Alexandru Lafkovici
Keyword(s):  
North American ◽  
Detection Efficiency ◽  
Lightning Discharge ◽  
Location Error ◽  
Error Ellipse ◽  
Semi Major Axis ◽  
North East ◽  
The North ◽  
Lightning Detection ◽  
Triggered Lightning

The North American Lightning Detection Network (NALDN) is a commercial lightning detection network operated by Vaisala Inc., and is composed of the U.S. National Lightning Detection Network (NLDN) and the Environment Canada owned Canadian Lightning Detection Network (CLDN). The CN Tower is one of the best sites in the world to observe the lightning phenomenon and provides an excellent opportunity to evaluate the performance of the NALDN in the Toronto area. Using CN Tower lightning data acquired during 2005, the performance characteristics of the NALDN were thoroughly evaluated, including the flash detection efficiency (DE), stroke DE, absolute location error, peak current estimation and location accuracy model (50%, 90% and 99% error ellipses) error. Although a similar test was performed using rocket-triggered lightning in Florida at Camp Blanding, this test evaluated a completely different region of the NALDN. Moreover, rocket-triggered lightning artificially initiates a lightning discharge, whereas lightning events to the CN Tower occur naturally and are similar to discharges that occur to tall structures or objects at high altitude or mountainous areas. Excluding two flashes understood to be composed of M-components, the NALDN detected 7 out of 7 flashes recorded at the CN Tower, resulting in a 100% flash DE. Furthermore, the NALDN detected 22 out of 39 strokes recorded at the CN Tower, resulting in a stroke DE of 56%. Relative to the CN Tower, the NALDN was found to have a median absolute location error of 0.356 km and a mean error of 0.390 km for the 22 strokes it detected. It was also demonstrated that the NALDN stroke location error seems to have a large bias towards the north of the CN Tower and a slight bias towards the east, with 19 of the 22 strokes predicted north-east of the CN Tower. The 50%, 90% and 99% error ellipses provided by the NALDN were also evaluated. It was found that 73% (16 out of the 22) detected strokes were enclosed by the 50% error ellipse, 91% (20 out of the 22) detected strokes were enclosed by the 90% error ellipse and 95% (21 out of the 22) detected strokes were enclosed by the 99% error ellipse. The minimum value for the 50% error ellipse axes is set at 0.4 km by Vaisala, and 21 out of the 22 detected strokes had a semi-major axis length of 0.4 km, suggesting that the median location error for CN Tower strokes is 0.4 or less. The 0.356 km median location error obtained for the 22 detected strokes appears to support this.

Helicopter Landing Ship: Undercarriage Strength and the Role of the Human Factor

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
E. Suhir
Keyword(s):  
Human Factor ◽  
Operation Time ◽  
Extreme Value Distribution ◽  
Mean Value ◽  
Helicopter Landing ◽  
The Times ◽  
The Moment ◽  
Normal Law ◽  
Time Required

We address, using probabilistic modeling and the extreme-value-distribution technique, the helicopter undercarriage strength in a helicopter-landing-ship situation. Our analysis contains an attempt to quantify, on the probabilistic basis, the role of the human factor in the situation in question. This factor is important from the standpoint of the operation time that affects the likelihood of safe landing during the lull period in the sea condition. The operation time includes (1) the time required for the officer-on-ship-board and the helicopter pilot to make their go-ahead decisions and (2) the time of actual landing. It is assumed, for the sake of simplicity, that both these times could be approximated by Rayleigh’s law, while the lull duration follows the normal law with a high enough ratio of the mean value to the standard deviation. Safe landing could be expected if the probability that it occurs during the lull time is sufficiently high. The probability that the helicopter undercarriage strength is not compromised can be evaluated as a product of the probability that landing indeed occurs during the lull time and the probability that the relative velocity of the helicopter undercarriage with respect to the ship’s deck at the moment of encounter does not exceed the allowable level. This level is supposed to be determined for the helicopter-landing-ground situation. The developed model can be used when developing specifications for the undercarriage strength, as well as guidelines for personnel training. Particularly, the model can be of help when establishing the times to be met by the two humans involved to make their go-ahead decisions for landing and to actually land the helicopter. Plenty of additional risk analyses (associated with the need to quantify various underlying uncertainties) and human psychology related efforts will be needed, of course, to make such guidelines practical.

Outcomes of infants undergoing laparoscopic pyeloplasty: A single-center experience

2018 ◽  
Vol 86 (1) ◽  
pp. 27-31 ◽  
Author(s):  
İbrahim Erol ◽  
Kaan Karamık ◽  
Mahmut Ekrem İslamoğlu ◽  
Mutlu Ateş ◽  
Murat Savaş
Keyword(s):  
Operation Time ◽  
Significant Degree ◽  
Stent Migration ◽  
Mean Value ◽  
Laparoscopic Pyeloplasty ◽  
Mean Values ◽  
Single Center Experience ◽  
The Mean ◽  
Split Function

Purpose: The aim of this study was to evaluate the outcomes of laparoscopic pyeloplasty in children less than 12 months of age. Materials and methods: The records of 20 infants, who had pelviureteric junction obstruction and subsequently underwent LP from January 2013 to November 2016 with at least 1 year of follow-up, were retrospectively reviewed. Patients demographics, the results of preoperative and postoperative imaging studies, perioperative details, complications, and results were noted. Results: The mean age of 20 infants was 4.75 months. The gender of cases was 5 females (25%) and 15 males (75%). Of that, 13 (65%) laparoscopic pyeloplasties were in left side and 7 (35%) were in right side. No cases needed open conversation. Aberrant crossing vessel was observed in three patients (15%). The mean operation time was 79.35 min (45–128 min). The mean hospital stay was 2.9 ± 0.308 days (2–3 days). There were complications in three children (15%); two patients developed stent migration and one child had fever over 38°. Three children with complications did not require a second intervention. In one child, the kidney was non-functioning in follow-up and nephrectomy was performed. The anteroposterior diameter significantly reduced. Preoperative mean value was 24.305 ± 5.6157 and postoperative mean value was 15.40 ± 6.030 (p = 0.000, p < 0.05). There was a significant degree of improvement in renal split function for all patients. Preoperative mean values were 45.53 ± 11.512, while postoperative values were 47.850 ± 13.347 (p = 0.029, p < 0.05). Conclusion: Although there are doubts about the reliability and efficacy of results for pyeloplasty in children less 12 months, many studies including this study show that laparoscopic pyeloplasty is an effective and reliable method for infants.

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