• Title, Summary, Keyword: regression formulas

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Modelling the flexural strength of mortars containing different mineral admixtures via GEP and RA

  • Saridemir, Mustafa
    • Computers and Concrete
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    • v.19 no.6
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    • pp.717-724
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    • 2017
  • In this paper, four formulas are proposed via gene expression programming (GEP)-based models and regression analysis (RA) to predict the flexural strength ($f_s$) values of mortars containing different mineral admixtures that are ground granulated blast-furnace slag (GGBFS), silica fume (SF) and fly ash (FA) at different ages. Three formulas obtained from the GEP-I, GEP-II and GEP-III models are constituted to predict the $f_s$ values from the age of specimen, water-binder ratio and compressive strength. Besides, one formula obtained from the RA is constituted to predict the $f_s$ values from the compressive strength. To achieve these formulas in the GEP and RA models, 972 data of the experimental studies presented with mortar mixtures were gathered from the literatures. 734 data of the experimental studies are divided without pre-planned for these formulas achieved from the training and testing sets of GEP and RA models. Beside, these formulas are validated with 238 data of experimental studies un-employed in training and testing sets. The $f_s$ results obtained from the training, testing and validation sets of these formulas are compared with the results obtained from the experimental studies and the formulas given in the literature for concrete. These comparisons show that the results of the formulas obtained from the GEP and RA models appear to well compatible with the experimental results and find to be very credible according to the results of other formulas.

New explicit formulas for optimum design of concrete gravity dams

  • Habibi, Alireza;Zarei, Sajad;Khaledy, Nima
    • Computers and Concrete
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    • v.27 no.2
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    • pp.143-152
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    • 2021
  • Large dams are a part of the infrastructure of any society, and a huge amount of resources are consumed to build them. Among the various types of dams, the optimum design of concrete gravity dams requires special attention because these types of dams require a huge amount of concrete for their construction. On the other hand, concrete gravity dams are among the structures whose design, regarding the acting forces, geometric parameters, and resistance and stability criteria, has some complexities. In the present study, an optimization methodology is proposed based on Sequential Quadratic Programming (SQP), and a computer program is developed to perform optimization of concrete gravity dams. The optimum results for 45 concrete gravity dams are studied and regression analyses are performed to obtain some explicit formulas for optimization of the gravity dams. The optimization of concrete gravity dams can be provided easily using the developed formulas, without the need to perform any more optimization process.

A Study on the Resistance and Wake Characteristics of a Full Ship Series

  • Rhyu, Seong-Sun;Kim, Hyo-chul
    • Journal of Ship and Ocean Technology
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    • v.1 no.1
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    • pp.15-25
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    • 1997
  • A series of towing tank tests were carried out for 18 full ship models of high block coefficients. The resistance coefficients and wake distribution at the propeller plane were measured and carefully examined. Regression analysis was employed to find out the relationships with the hull form parameters. Equations for wave resistance coefficient, form factor, and nominal wake are given. A harmonic analysis of measured wake was performed to look into the influence of the local stern shape on the magnitude of fluctuating wake components at three different radii. The amplitude of wake harmonics was also expressed by regression quations. It was found that the regression formulas were very useful in estimating resistance and circumferential wake characteristics of full ship models. It was also considered that the formulas presented in this paper could be utilized in the hull form improvement in a preliminary design.

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Determination of Probable Rainfall Intensity Formulas for Designing Storm Sewer Systems at Incheon District (우수거 설계를 위한 인천지방에서의 확률강우강도식의 산정)

  • Ahn, Tae-Jin;Kim, Kyung-Sub
    • Journal of Korean Society of Water and Wastewater
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    • v.12 no.3
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    • pp.99-106
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    • 1998
  • This paper presents a procedure for determining the design rainfall depth and the design rainfall intensity at Incheon city area in Korea. In this study the eight probability distributions are considered to estimate the probable rainfall depths for 11 different durations. The Kolmogorov - Smirnov test and the Chi-square test are adopted to test each distribution. The probable rainfall intensity formulas are then determined by i) the least squares (LS) method, ii) the least median squares (LMS) method, iii) the reweighted least squares method based on the LMS (RLS), and iv) the constrained regression (CR) model. The Talbot, the Sherman, the Japanese, and the Unified type are considered to determine the best type for the Incheon station. The root mean squared (RMS) errors are computed to test the formulas derived by four methods. It is found that the Unified type is the most reliable and that all methods presented herein are acceptable for determining the coefficients of rainfall intensity formulas from an engineering point of view.

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Estimation of fundamental natural period of vibration for reinforced concrete shear walls systems

  • Shatnawi, Anis S.;Al-Beddawe, Esra'a H.;Musmar, Mazen A.
    • Earthquakes and Structures
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    • v.16 no.3
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    • pp.295-310
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    • 2019
  • This study attempts to develop new simplified approximate formulas to predict the fundamental natural periods of vibration (T) for bearing wall systems engaged with special reinforced concrete shear walls (RCSW) under seismic loads. Commonly, seismic codes suggested empirical formulas established by regression analysis of measured T for buildings during earthquake motions. These formulas depend on structure type, building height, number, height and length of SW, and ratio of SW area to base area of structure. In this study, a parametric investigation is performed for T of 110 selected models of bearing RCSW systems with varying structural height, configuration of horizontal plans including building width, number and width of bays, presence of middle corridors and core SWs. For this purpose, a 3D non-linear response time history (TH) analysis is implemented using ETABS v16.2.1. New formulas to estimate T are anticipated and compared with those obtained from formulas of IBC 2012 and ASCE/SEI 7-10. Moreover, the study examines responses of an arbitrarily two selected test model of 60 m and 80 m in height with presence of SWs having middle corridors. It is observed that the performance of the tested buildings is different through arising of considerable errors when using codes' formulas for estimating T. Accordingly, using the present proposed formulas exhibits more reasonable and safer design compared to codes' formulas. The results showed that equitable enhancement is promising to improve T formulas approaching enhanced and accurate estimation of T with reliable analysis, design, and evaluation of bearing RCSW systems.

Estimation of the Fundamental Period for Residential Buildings with Shear-Wall System

  • Chun, Young-Soo;Chang, Kug-Kwan;Lee, Li-Hyung
    • KCI Concrete Journal
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    • v.12 no.1
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    • pp.121-130
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    • 2000
  • This study focused on evaluating the reliability of code formulas such as those of the current Korean Building Code(KBC 1988). UBC 1997, NBCC 1995. and BSLJ 1994 for estimating the fundamental period of RC apartment buildings with shear-wall dominant systems, representative of typical residential buildings in Korea. For this purpose, full-scale measurements were carried out on fifty RC apartment buildings, and these results were compared to those obtained by code formulas and also by dynamic analysis. Although these code formulas are based on the measured periods of buildings during various earthquakes and building period varies with the amplitude of structural deflection or strain level, ambient surveys should provide an effective tool for experimentally verifying the design period to the completed building. This comparison shows that comparatively large errors are likely to occure when the code formula of KBC 1988 is used, and all the other code formulas are not sufficient to estimate the fundamental period of apartment buildings with shear-wall dominant systems. An improved formula is proposed by regression analysis on the basis of the measured period data. The proposal is for the servicebility stress level, but it can also be applied for seismic code in the regions of low seismicity similar to Korea.

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ON MARGINAL INTEGRATION METHOD IN NONPARAMETRIC REGRESSION

  • Lee, Young-Kyung
    • Journal of the Korean Statistical Society
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    • v.33 no.4
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    • pp.435-447
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    • 2004
  • In additive nonparametric regression, Linton and Nielsen (1995) showed that the marginal integration when applied to the local linear smoother produces a rate-optimal estimator of each univariate component function for the case where the dimension of the predictor is two. In this paper we give new formulas for the bias and variance of the marginal integration regression estimators which are valid for boundary areas as well as fixed interior points, and show the local linear marginal integration estimator is in fact rate-optimal when the dimension of the predictor is less than or equal to four. We extend the results to the case of the local polynomial smoother, too.

Comparative Study of Age Estimation Accuracy in Gustafsonss Method and Prediction Formula by Multiple Regression (다변인회귀분석법과 Gustafson 방법에 의한 연령감정 정확도의 비교연구)

  • 곽경환;김종열
    • Journal of Oral Medicine and Pain
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    • v.10 no.1
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    • pp.73-89
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    • 1985
  • This study comprised 157 extracted teeth, 73 of the teeth originated from mates and 84 from females, the age range was 12-79 years. The correlation coefficient of each Gustafson's criteria in relation to age was carried out. Age estimation were performed on 157 teeth according to the method by Gustafson and by use of multiple regression, as used by Johanson, after evaluating the six criteria of Gustafson by multiple regression computer analysis. Two prediction formulas and standard deviations were compared with each other. The results were as follows : 1. The author found that six Gustafson's criteria had strong correlation with age except root resorption, and correlation coefficients were r = 0.79 (Transparent dentin), r=0.72 (Secondary dentin), r 0.69 (Periodontal change), r=0.63(Attrition), r = 0.39 (Root resorption), respecti vely. 2. The age estimation formula by Gustafson's method was calculated as follows: Y 8.88 + 3.52X r =0.87, r2 = 0.76, SD = 8.18, F = 483.56, P < 0.01 The age estimation formula by multiple regression was calculated as follows: Y 8.57 + 6.37T + 6.37T + 4.63P + 2.70S + 2.40C + 3.08A + 1.34R r= 0.89, r2 = 0.78, SD = 7.82, F = 91.62, P < 0.01, Durbin-Watson Coefficient = 1.09 3. In comparison of two estimation formulas, the formula by multiple regression, the method of Johanson, was found to be slightly more reliable than Gustafson's method. Gustafson's method SD = 8.18, Multiple regression (Johanson's method) SD = 7.82 4. It was reaffirmed that Gustafson's six criteria could be a independent variable in multiple regression analysis.

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Development of the Basic Bodice Pattern Depending on Shoulder Types -focused on young women in their twenties- (어깨 유형에 따른 길 원형 설계 -20대 여성 중심으로-)

  • 김민진;이정란
    • Journal of the Korean Society of Clothing and Textiles
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    • v.27 no.5
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    • pp.463-474
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    • 2003
  • In this research, adult women's shoulder types were Classified through direct and indirect measurements to present a judging individual body size according to the type. Also, regression formula by shoulder types were calculated and presented the basic bodice pattern. The results were as follows: 1. The result of factor analysis indicated that 6 factors were extracted through factor analysis and those factors comprised 66.1 to of total variance. 2. By using factor scores, cluster analysis was carried out and subject were classified into 5 clusters. Type 1 was the inclined shoulders, wide shoulders and passive posture. Type 2 was the front type shoulders and active posture. Type 3 was the thick shoulders and back type shoulders. Type 4 was the narrow shoulders. Type f was the drooped shoulders, thin shoulder and sway posture. 3. The body types of individuals were judged by discriminant analysis. 4. After setting 4 items such as the bust girth, posterior waist length, neck base girth and waist girth as representative items and regression formulas were presented. the superiority of the final basic bodice patterns were demonstrated by high approval rate of the subjects who participated in testing.