scholarly journals CORRELATION-SPECTRAL ANALYSIS OF THE TOPOGRAPHY OF ENGINEERING SURFACES AT THE NANOSCALE LEVEL

2021 ◽  
pp. 457-464
Author(s):  
Владимир Васильевич Измайлов ◽  
Марина Вячеславовна Новоселова
Keyword(s):  
Spectral Density ◽  
Normal Distribution ◽  
Random Process ◽  
Goodness Of Fit ◽  
Random Noise ◽  
Low Frequency ◽  
Surface Profile ◽  
Wide Band ◽  
Goodness Of Fit Test ◽  
Significance Level

Исследована нанотопография некоторых типичных технических поверхностей и экспериментально определены характеристики профиля наношероховатости как случайного процесса - автокорреляционная функция и спектральная плотность. Показано, что для исследованных поверхностей их профилограммы могут рассматриваться как реализации случайного стационарного нормального эргодического процесса. Проведена визуальная проверка нормальности процесса сравнением экспериментальных значений ординат профиля с теоретическими значениями, подчиняющимися нормальному распределению, а также сравнением полигона частот с теоретической функцией плотности вероятности нормального распределения. Количественное подтверждение нормальности процесса выполнено с применением критерия согласия Колмогорова. Показано, что на уровне значимости p = 0,05 гипотеза о нормальности случайного процесса (профиля наношероховатости поверхности) не противоречит экспериментальным результатам. Определены интервалы корреляции рассмотренных процессов. Вид автокорреляционных функций и величины интервалов корреляции говорят о случайном характере профиля поверхности: на интервале, равном одному - двум средним значениям шага неровностей профиля его ординаты становятся практически некоррелированными. Графики спектральных плотностей свидетельствуют о том, что профиль поверхности можно рассматривать как широкополосный случайный шум с преобладанием низкочастотных составляющих. The nanotopography of some typical technical surfaces is investigated and the characteristics of the nanoroughness profile as a random process are experimentally determined - the autocorrelation function and spectral density. It is shown that for the investigated surfaces, their profilograms can be considered as realizations of a random stationary normal ergodic process. A visual check of the process normality was carried out by comparing the experimental values of the profile ordinates with theoretical values obeying the normal distribution, as well as by comparing the frequency polygon with the theoretical probability density function of the normal distribution. Quantitative confirmation of the process normality was carried out using the Kolmogorov goodness-of-fit test. It is shown that at the significance level p = 0,05, the hypothesis about the normality of a random process (surface nanoroughness profile) does not contradict the experimental results. The correlation intervals of the considered processes are determined. The form of the autocorrelation functions and the values of the correlation intervals indicate the random nature of the surface profile: in the interval equal to one or two average values of the step of the irregularities of the profile, its ordinates become practically uncorrelated. Spectral density plots indicate that the surface profile can be considered as a wide-band random noise with a predominance of low-frequency components.

scholarly journals PEMILIHAN DISTRIBUSI PROBABILITAS PADA ANALISA HUJAN DENGAN METODE GOODNESS OF FIT TEST

2016 ◽  
Vol 18 (2) ◽  
pp. 139-148
Author(s):  
Togani Cahyadi Upomo ◽  
Rini Kusumawardani
Keyword(s):  
Normal Distribution ◽  
Goodness Of Fit ◽  
Gumbel Distribution ◽  
Rainfall Event ◽  
Goodness Of Fit Test ◽  
Chi Square ◽  
Chi Square Test ◽  
Log Normal ◽  
Log Normal Distribution ◽  
Pearson Iii Distribution

Rainfall event is a stochastic process, so to explain and analyze this processes the probability theory and frequency analysisare used. There are four types of probability distributions.They are normal, log normal, log Pearson III and Gumbel. To find the best probabilities distribution, it will used goodness of fit test. The tests consist of chi-square and smirnov-kolmogorov. Results of the chi-square test for normal distribution, log normal and log Pearson III was 0.200, while for the Gumbel distribution was 2.333. Results of Smirnov Kolmogorov test for normal distribution D = 0.1554, log-normal distribution D = 0.1103, log Pearson III distribution D = 0.1177 and Gumbel distribution D = 0.095. All of the distribution can be accepted with a confidence level of 95%, but the best distribution is log normal distribution.Kejadian hujan merupakan proses stokastik, sehingga untuk keperluan analisa dan menjelaskan proses stokastik tersebut digunakan teori probabilitas dan analisa frekuensi. Terdapat empat jenis distribusi probabilitas yaitu distribusi normal, log normal, log pearson III dan gumbel. Untuk mencari distribusi probabilitas terbaik maka akan digunakan pengujian metode goodness of fit test. Pengujian tersebut meliputi uji chi-kuadrat dan uji smirnov kolmogorov. Hasil pengujian chi kuadrat untuk distribusi normal, log normal dan log pearson III adalah 0.200, sedangkan untuk distribusi gumbel 2.333. Hasil pengujian smirnov kolmogorov untuk distribusi normal dengan nilai D = 0.1554, distribusi log normal dengan nilai D = 0.1103, distribusi log pearson III dengan nilai D = 0.1177 dan distribusi gumbel dengan nilai D = 0.095. Seluruh distribusi dapat diterima dengan tingkat kepercayaan 95%, tetapi distribusi terbaik adalah distribusi log normal.

scholarly journals EFFECT OF ROAD SURFACE DEFORMATIONS ON LATERAL LANE UTILIZATION AND LONGITUDINAL DRIVING BEHAVIOURS

Transport ◽  
2016 ◽  
Vol 31 (2) ◽  
pp. 192-201 ◽  
Author(s):  
Metin Mutlu Aydin ◽  
Ali Topal
Keyword(s):  
Normal Distribution ◽  
Goodness Of Fit ◽  
Lateral Position ◽  
Road Surface ◽  
Goodness Of Fit Test ◽  
Chi Square ◽  
Rural Roads ◽  
Location Data ◽  
Surface Deformations ◽  
Lane Utilization

Various road surface deformations generally occur on urban and rural roads due to infrastructure, superstructure deficiencies and excessive heavy vehicle loads. In addition to driver-based errors, many accidents happen due to these mentioned surface deformations. This study aims to present lateral lane utilization and longitudinal driving behaviours on a two-lane deformed road. The effect of deformation on the tendency of drivers’ lane selection, lane utilization, and the movement in traffic flow will also be determined. For this purpose, parameters such as lateral position, speed, acceleration/deceleration and location data of vehicles travelling through four different deformation zones on a two-lane road in Izmir (Turkey), were collected. Based on the fact that in ideal conditions, distribution of lateral positions of vehicles in a lane is similar to normal distribution. The collected data was evaluated with chi-square (χ2) goodness of fit test to see if they are fit to normal distribution or not. This study concluded that if a deformation zone has wider area and less depth, it will be less effective on lateral lane utilization of vehicles. It was also obtained from the results that variation in other parameters such as deformation type, depth and height are associated with the lateral lane utilization of drivers. Additionally, the drivers’ characteristics such as perception and aggressiveness are seen as the most important factors influencing the longitudinal vehicle behaviours while passing through the deformation zones.

scholarly journals Estimation of Saturation Flow Rates at Signalized Intersections

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Chang-qiao Shao ◽  
Xiao-ming Liu
Keyword(s):  
Normal Distribution ◽  
Flow Rate ◽  
Goodness Of Fit ◽  
Estimation Method ◽  
Fundamental Parameter ◽  
Goodness Of Fit Test ◽  
Flow Rates ◽  
Average Value ◽  
Saturation Flow Rate ◽  
Saturation Flow

The saturation flow rate is a fundamental parameter to measure the intersection capacity and time the traffic signals. However, it is revealed that traditional methods which are mainly developed using the average value of observed queue discharge headways to estimate the saturation headway might lead to underestimate saturation flow rate. The goal of this paper is to study the stochastic nature of queue discharge headways and to develop a more accurate estimate method for saturation headway and saturation flow rate. Based on the surveyed data, the characteristics of queue discharge headways and the estimation method of saturated flow rate are studied. It is found that the average value of queue discharge headways is greater than the median value and that the skewness of the headways is positive. Normal distribution tests were conducted before and after a log transformation of the headways. The goodness-of-fit test showed that for some surveyed sites, the queue discharge headways can be fitted by the normal distribution and for other surveyed sites, the headways can be fitted by lognormal distribution. According to the queue discharge headway characteristics, the median value of queue discharge headways is suggested to estimate the saturation headway and a new method of estimation saturation flow rates is developed.

scholarly journals Developing assesment instruments for the sensory acceptability of food products

2017 ◽  
Vol 3 (1) ◽  
pp. 92
Author(s):  
Sugiyono Sugiyono ◽  
Djemari Mardapi ◽  
I Gusti Putu Suryadarma
Keyword(s):  
High School Students ◽  
Construct Validity ◽  
Empirical Evidence ◽  
Goodness Of Fit ◽  
Face Validity ◽  
Reliability Estimate ◽  
Vocational High School ◽  
School Students ◽  
Goodness Of Fit Test ◽  
Significance Level

The study investigated the constructs and characteristics of physiological, psychological, and sensory instruments. The data were collected by means of a questionnaire, physiological instrument, psychological instrument, and sensory instrument. The expert judgment conclusions were calculated by means of Aiken formula; the instrument construct validity was analyzed with confirmatory factor analysis by the goodness-of-fit test at the significance level of 0.05; the reliability estimate by generalizability with a G-study coefficient ≥ 0.7 and an ICC coefficient ≥ 0.7; and the instrument characteristics were analyzed by D-study. The results of the study are as follows: (1) the physiological instrument consisted of nine constructs: four constructs of psychological instrument and  five constructs of sensory instrument; (2) three instruments had good face validity, content validity and construct validity, supported by the empirical evidence at p > 0.05; (3) the reliability estimate of the three instruments was good and the reliability estimate was supported by empirical evidence with G coefficients of > 0.7 and ICC coefficients of > 0.7, (4) the three instruments had characteristics that might be appropriate to be used by the university students of culinary program and the vocational high school students of culinary program.

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