scholarly journals The Evaluation of a New Method to Detect Mixing Layer Heights Using Lidar Observations

2015 ◽  
Vol 32 (11) ◽  
pp. 2041-2051 ◽  
Author(s):  
Micheal Hicks ◽  
Ricardo Sakai ◽  
Everette Joseph
Keyword(s):  
Hybrid Method ◽  
Detection Method ◽  
Error Function ◽  
Mixing Layer ◽  
New Method ◽  
Mixing Height ◽  
Critical Components ◽  
Sky Conditions ◽  
Aerosol Backscatter ◽  
Lidar Observations

AbstractA new automatic mixing layer height detection method for lidar observations of aerosol backscatter profiles is presented and evaluated for robustness. The new detection method incorporates the strengths of Steyn et al.’s error function–ideal profile (ERF) method and Davis et al.’s wavelet covariance transform (WCT) method. These two methods are critical components of the new method, and their robustness is also evaluated and then contrasted to the new method. The new method is applied to aerosol backscatter observations in two ways: 1) by looking for the most realistic mixing height throughout the entire profile and 2) by searching for mixing height below significant elevated obscurations (e.g., clouds or aerosol layers). The first approach is referred to as the hybrid method and the second as the hybrid-lowest method. Coincident radiosounding observations of mixing heights are used to independently reference the lidar-based estimates.There were 4030 cases examined over a 5-yr period for mixing heights. The efficacy of the lidar-based methods was determined based on diurnal, seasonal, stability, and sky obscuration conditions. Of these conditions, the hybrid method performed best for unstable and cloudy situations. It determined mixing heights reliably (less than ±0.30-km bias) for close to 70% of those cases. The hybrid-lowest method performed best in stable and clear-sky conditions; it determined mixing heights reliably for over 70% of those cases. The WCT method performed the best overall.

scholarly journals Daytime Cloud Detection Method Using the All-Sky Imager over PERMATApintar Observatory

Universe ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 41
Author(s):  
Mohammad Afiq Dzuan Mohd Azhar ◽  
Nurul Shazana Abdul Hamid ◽  
Wan Mohd Aimran Wan Mohd Kamil ◽  
Nor Sakinah Mohamad
Keyword(s):  
Detection Method ◽  
Color Difference ◽  
Database System ◽  
New Method ◽  
Cloud Detection ◽  
Cloud Coverage ◽  
B Method ◽  
Difference Methods ◽  
Sky Imager ◽  
Sky Conditions

In this study, we explored a new method of cloud detection called the Blue-Green (B-G) Color Difference, which is adapted from the widely used Red-Blue (R-B) Color Difference. The objective of this study was to test the effectiveness of these two methods in detecting daytime clouds. Three all-sky images were selected from a database system at PERMATApintar Observatory. Each selected all-sky image represented different sky conditions, namely clear, partially cloudy and overcast. Both methods were applied to all three images and compared in terms of cloud coverage detection. Our analysis revealed that both color difference methods were able to detect a thick cloud efficiently. However, the B-G was able to detect thin clouds better compared to the R-B method, resulting in a higher and more accurate cloud coverage detection.

scholarly journals Mixing height determination by ceilometer

2006 ◽  
Vol 6 (6) ◽  
pp. 1485-1493 ◽  
Author(s):  
N. Eresmaa ◽  
A. Karppinen ◽  
S. M. Joffre ◽  
J. Räsänen ◽  
H. Talvitie
Keyword(s):  
Mixed Layer ◽  
Mixing Height ◽  
Backscatter Signal ◽  
Clear Sky ◽  
Height Estimates ◽  
Height Determination ◽  
Novel Method ◽  
Sky Conditions ◽  
Aerosol Backscatter ◽  
Good Agreement

Abstract. A novel method for estimating the mixing height based on ceilometer measurements is described and tested against commonly used methods for determining mixing height. In this method an idealised backscatter profile is fitted to the observed backscatter profile. The mixing height is one of the idealised backscatter profile parameters. An extensive amount of ceilometer data and vertical soundings data from the Helsinki area in 2002 is utilized to test the applicability of the ceilometer for mixing height determination. The results, including 71 convective and 38 stable cases, show that in clear sky conditions the mixing heights determined from ceilometer based aerosol profiles and BL-height estimates based on sounding data are in a good agreement. Rejected outlier cases corresponded to very low aerosol concentrations in the mixed layer leading to a very weak aerosol backscatter signal in the lowest layer.

scholarly journals Mixing height determination by ceilometer

2005 ◽  
Vol 5 (6) ◽  
pp. 12697-12722 ◽  
Author(s):  
N. Eresmaa ◽  
A. Karppinen ◽  
S. M. Joffre ◽  
J. Räsänen ◽  
H. Talvitie
Keyword(s):  
Mixed Layer ◽  
Mixing Height ◽  
Backscatter Signal ◽  
Clear Sky ◽  
Height Estimates ◽  
Height Determination ◽  
Novel Method ◽  
Sky Conditions ◽  
Aerosol Backscatter ◽  
Good Agreement

Abstract. A novel method for estimating the mixing height based on ceilometer measurements is described and tested against commonly used methods for determining mixing height. In this method an idealised backscatter profile is fitted to the observed backscatter profile. The mixing height is one of the idealised backscatter profile parameters. An extensive amount of ceilometer data and vertical soundings data from the Helsinki area in 2002 is utilized to test the applicability of the ceilometer for mixing height determination. The results, including 71 convective and 38 stable cases, show that in clear sky conditions the mixing heights determined from ceilometer based aerosol profiles and BL-height estimates based on sounding data are in a good agreement. Rejected outlier cases corresponded to very low aerosol concentrations in the mixed layer leading to a very weak aerosol backscatter signal in the lowest layer.

scholarly journals Over/Undervoltage and Undervoltage Shift of Hybrid Islanding Detection Method of Distributed Generation

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Manop Yingram ◽  
Suttichai Premrudeepreechacharn
Keyword(s):  
Control System ◽  
Distributed Generation ◽  
Hybrid Method ◽  
Detection Method ◽  
System Simulation ◽  
Detection Methods ◽  
Islanding Detection ◽  
Active Method ◽  
Passive Method ◽  
Simulation Results

The mainly used local islanding detection methods may be classified as active and passive methods. Passive methods do not perturb the system but they have larger nondetection zones, whereas active methods have smaller nondetection zones but they perturb the system. In this paper, a new hybrid method is proposed to solve this problem. An over/undervoltage (passive method) has been used to initiate an undervoltage shift (active method), which changes the undervoltage shift of inverter, when the passive method cannot have a clear discrimination between islanding and other events in the system. Simulation results on MATLAB/SIMULINK show that over/undervoltage and undervoltage shifts of hybrid islanding detection method are very effective because they can determine anti-islanding condition very fast.ΔP/P>38.41% could determine anti-islanding condition within 0.04 s;ΔP/P<-24.39% could determine anti-islanding condition within 0.04 s;-24.39%≤ΔP/P≤ 38.41% could determine anti-islanding condition within 0.08 s. This method perturbed the system, only in the case of-24.39% ≤ΔP/P ≤38.41% at which the control system of inverter injected a signal of undervoltage shift as necessary to check if the occurrence condition was an islanding condition or not.

Height-dependent meteor temperatures and comparisons with lidar and OH measurements

2007 ◽  
Vol 85 (2) ◽  
pp. 173-187 ◽  
Author(s):  
W K Hocking ◽  
P S Argall ◽  
R P Lowe ◽  
R J Sica ◽  
H Ellinor
Keyword(s):  
Good Accuracy ◽  
Sufficient Accuracy ◽  
New Method ◽  
Precise Knowledge ◽  
Rayleigh Lidar ◽  
Sky Conditions

A new method is introduced that allows meteor radars to potentially produce height-dependent temperatures, rather than simply averages over the meteor region. The method is applied to data from the Clovar radar, near London, Ontario, and then a three-way comparison between Rayleigh lidar temperatures, hydroxyl temperatures, and meteor temperatures is undertaken. The three methods prove to be complementary. The OH measurements have good accuracy, but suffer slightly from lack of precise knowledge about their height and the fact that they are effectively integrated over the depth of the OH layer. The lidar temperatures are measured at well-defined altitudes and have better accuracy than the meteor method. The meteor temperatures have the largest errors, but still provide sufficient accuracy for many types of atmospheric studies, and have the advantage that these measurements can be made 24 h a day and in all sky conditions (including during cloud and strong sunlight and moonlight). The measurements from these instruments are complementary in that they are useful for studying the temperature on different time and altitude scales. PACS No.: 94.10.Dy

scholarly journals EFFICIENT LINE DETECTION METHOD BASED ON 2D CONVOLUTION FILTER

2021 ◽  
Vol 11 (4) ◽  
pp. 22-27
Author(s):  
Paweł Kowalski ◽  
Piotr Tojza
Keyword(s):  
Detection Method ◽  
Computational Cost ◽  
New Method ◽  
Line Detection ◽  
Curve Detection ◽  
Real Time Image ◽  
Convolution Filter ◽  
Straight Lines ◽  
Time Image ◽  
Local Detection

The article proposes an efficient line detection method using a 2D convolution filter. The proposed method was compared with the Hough transform, the most popular method of straight lines detection. The developed method is suitable for local detection of straight lines with a slope from -45˚ to 45˚.  Also, it can be used for curve detection which shape is approximated with the short straight sections. The new method is characterized by a constant computational cost regardless of the number of set pixels. The convolution is performed using the logical conjunction and sum operations. Moreover, design of the developed filter and the method of filtration allows for parallelization. Due to constant computation cost, the new method is suitable for implementation in the hardware structure of real-time image processing systems.

scholarly journals Hybrid Method for Detecting Duplicate Image by Using Image Retrieval Technique in Data Mining

2021 ◽  
Vol 09 (04) ◽  
Author(s):  
Dr. S. Thavamani ◽  
Keyword(s):  
Data Mining ◽  
Image Retrieval ◽  
Hybrid Method ◽  
Video Retrieval ◽  
New Method ◽  
Computational Time ◽  
Storage Space ◽  
Copy Detection ◽  
Retrieval Technique ◽  
Improved Accuracy

Duplicated images cause several problems in online sites, so these demand special attention. To address the disadvantages of frames copy detection, the Hybrid Method of Detecting Duplicate Image by Using Image Retrieval Technique in Data Mining was proposed. We use the new method of eliminating duplicates in this example. To address the disadvantages of frames copy detection, the Hybrid Method of Detecting Duplicate Image by Using Image Retrieval Technique in Data Mining was proposed. The new method of eliminating duplicates in this example has proposed. Using this method, you can get rid of frames that aren't relevant to the video. This makes for more precise and faster video retrieval with fewer duplicates. As a back end, this technique is implemented in C# and SQL. The findings are put to the test and compared to the current SIFT process. The results showed that the output improved accuracy while reducing storage space, computational time, and memory use.

scholarly journals New Edge Detection Method for Indonesian Batik

2011 ◽  
Vol 2 (1) ◽  
Author(s):  
Thomas Adi Purnomo Shidi ◽  
Suyoto Suyoto
Keyword(s):  
Image Processing ◽  
Computer Vision ◽  
Edge Detection ◽  
Detection Method ◽  
New Method ◽  
Analysis Method ◽  
Unique Pattern ◽  
Detection Analysis ◽  
Edge Detection Method

Abstrak. Metode Baru Deteksi Tepi untuk Batik Indonesia. Didalam paper ini, diusulkan sebuah metode pendeteksi baru untuk motif batik. Deteksi tepi sudah sangat sering digunakan didalam pemrosesan gambar. Batik motif adalah salah satu contoh gambar yang memiliki bentuk yang unik dan menarik untuk dianalisis. Metode yang digunakan pada paper ini adalam metode canny dan prewit dan akan menghasilkan metode baru yaitu metode Thomas. Perbedaan antara metode dan hasil akan dilihat dari sisi ketepatan, qualitas hasil dan kejelasan. Contoh batik yang akan digunakan adalah motif parang, motife lereng dan udan liris. Ketiga batik tersebut memiliki pola  yang unik. Kata kunci : Canny, Prewitt, Thomas, Batik, Parang, Lereng, Udan liris. Abstract. New Edge Detection Method for Indonesian Batik. In this paper, we propose a new edge detection analysis method on batiks motif. Edge detection has been oftenly  used in computer vision and image processing. Indonesian  Batiks motif are some example of graphic picture that has unique pattern that interesting to analyse. The method that used for example on this paper are canny and prewit and produce a new method, thomas method. the different  amongs the method, the result of comparison appears on quality, accuracy and clarity. The example that we use are parang batiks motive, lereng batiks motive, and udan liris batiks motive. Three of batiks motive above are have unique pattern. Keywords: Canny, Prewitt, Thomas, Batik, Parang, Lereng, Udan liris.

The Application of Transient Electromagnetic Method in Detecting the Corrosion of Heat Distribution Pipeline

2014 ◽  
Vol 556-562 ◽  
pp. 3052-3055
Author(s):  
Bo Hu ◽  
Jian Liu ◽  
Run Qiao Yu
Keyword(s):  
Detection Method ◽  
New Method ◽  
Electromagnetic Method ◽  
Economic Losses ◽  
Heat Distribution ◽  
Uniform Corrosion ◽  
Transient Electromagnetic Method ◽  
Safe Operation ◽  
Corrosion Detection ◽  
Transient Electromagnetic

Leakage of the heat distribution pipeline will seriously affect the safety of residents and cause economic losses. This paper presents the transient electromagnetic method (TEM) for detecting the corrosion of buried heat distribution pipeline, which mainly introduced the principle of the TEM to detect the pipeline and the general detection method. Combining with an instance of corrosion detection of buried heat distribution pipeline in a certain street in China Hohhot, the detection results were analyzed and the feasibility of this method was proved through excavation. The results show that the TEM can detect the uniform corrosion distribution of buried metal pipeline and it’s effective and practical for detecting the buried heat distribution pipeline. The TEM could provide a new method for guaranteeing the safe operation of the heat distribution pipeline.

Free Turbulent Shear Layers on Plug Nozzles

1977 ◽  
Vol 99 (2) ◽  
pp. 301-308
Author(s):  
C. J. Scott ◽  
D. R. Rask
Keyword(s):  
Turbulent Mixing ◽  
Schmidt Number ◽  
Error Function ◽  
Mixing Layer ◽  
Shear Layers ◽  
Turbulent Shear ◽  
Gas Chromatograph ◽  
Plug Nozzle ◽  
Turbulent Schmidt Number ◽  
Plug Nozzles

Two-dimensional, free, turbulent mixing between a uniform stream and a cavity flow is investigated experimentally in a plug nozzle, a geometry that generates idealized mixing layer conditions. Upstream viscous layer effects are minimized through the use of a sharp-expansion plug nozzle. Experimental velocity profiles exhibit close agreement with both similarity analyses and with error function predictions. Refrigerant-12 was injected into the cavity and concentration profiles were obtained using a gas chromatograph. Spreading factors for momentum and mass were determined. Two methods are presented to determine the average turbulent Schmidt number. The relation Sct = Sc is suggested by the data for Sc < 2.0.

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