Robust DERIVATIVE Operator into Gradient Based SIGNAL Processing

Hadi Sadoghi Yazdi,Hadi Dehdast 보안공학연구지원센터 2012 International Journal of Control and Automation Vol.5 No.4

Least mean square algorithm tuned by fuzzy c-means for impulsive noise suppression of gray-level images

Mahdipour Hossein-Abad Hadi,Khademi Morteza,Sadoghi Yazdi Hadi 보안공학연구지원센터(IJSIP) 2010 International Journal of Signal Processing, Image Vol.3 No.4

A Cross Decomposition Approach for the Optimization of the Petroleum Product Supply Chain

Hadi Mohammadi,Esmaile Khorram 대한산업공학회 2019 Industrial Engineeering & Management Systems Vol.18 No.1

This paper addresses the solution of a two-stage stochastic mixed integer programming model for an investment of planning problems applied to the petroleum products supply chain. In this context, we present the development of decomposition techniques for the stochastic Benders decomposition and Lagrangian relaxation methods. The combinational technique of cross decomposition is a suitable one for exact solution of the mixed integer programming problems which uses simultaneously the advantages of Lagrangian relaxation and Benders decomposition methods that each reinforces one another. The basic idea for this technique is the generation of suitable upper and lower bounds for the optimal value of the original problem at each iteration. In this paper, as far as cross decomposition algorithm is concerned, we present a new hybrid Lagrangian relaxation algorithm for updating the Lagrangian multiplier set, based on the combination of cutting-plane, sub-gradient and trust-region strategies. The convergence of this technique regarding the convergence of Benders decomposition method in finite iteration numbers has been guaranteed. Results suggest that the proposed approach is able to efficiently solve the problem under consideration, achieving better performance in terms of computational times as compared to other techniques.

Utility of FDG-PET/CT for the Detection and Characterization of Sternal Wound Infection Following Sternotomy

Hadi Hariri,Stéphanie Tan,Patrick Martineau,Yoan Lamarche,Michel Carrier,Vincent Finnerty,Sébastien Authier,Francois Harel,Matthieu Pelletier-Galarneau 대한핵의학회 2019 핵의학 분자영상 Vol.53 No.4

Purpose FDG-PET/CT has the potential to play an important role in the diagnosis of sternal wound infections (SWI). The purpose of this study was to analyze the diagnostic accuracy of FDG-PET/CT for SWI in patients following sternotomy. Methods We performed a single-center, retrospective analysis of patients who had undergone median sternotomy and FDG-PET/ CT imaging. The gold standard consisted of positive bacterial culture and/or the presence of purulent material at surgery. Qualitative patterns of sternal FDG uptake, SUVmax, and associated CT findings were determined, and an imaging scoring system was developed. The diagnostic performances were studied in both the recent (≤ 6 months between sternotomy and imaging) and remote surgery phase (> 6 months). Results A total of 40 subjects were identified with 11 confirmed SWI cases. Consensus interpretation was associated with a sensitivity of 91%and specificity of 97%. Combination of uptake patterns yielded an AUC of 0.96 while use of SUVmax yielded an AUC of 0.82. Conclusions Results suggest that FDG-PET/CT may be useful for the diagnosis of SWI with optimal diagnostic accuracy achieved by identifying specific patterns of uptake. SUVmax can be helpful in assessing subjects with remote surgery, but its use is limited in the context of recent surgery. Further studies are required to confirm these results.

Nanoindentation study of cementite size and temperature effects in nanocomposite pearlite: A molecular dynamics simulation

Hadi Ghaffarian,Ali Karimi Taheri,유승화,강건욱 한국물리학회 2016 Current Applied Physics Vol.16 No.9

We carry out molecular dynamics simulations of nanoindentation to investigate the effect of cementite size and temperature on the deformation behavior of nanocomposite pearlite composed of alternating ferrite and cementite layers. We find that, instead of the coherent transmission, dislocation propagates by forming a widespread plastic deformation in cementite layer. We also show that increasing temperature enhances the distribution of plastic strain in the ferrite layer, which reduces the stress acting on the cementite layer. Hence, thickening cementite layer or increasing temperature reduces the likelihood of dislocation propagation through the cementite layer. Our finding sheds a light on the mechanism of dislocation blocking by cementite layer in the pearlite.

Numerical simulation of compressive to tensile load conversion for determining the tensile strength of ultra-high performance concrete

Hadi Haeri,Nader Mirshekari,Vahab Sarfarazi,Mohammad Fatehi Marji 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.5

In this study, the experimental tests for the direct tensile strength measurement of Ultra-High Performance Concrete (UHPC) were numerically modeled by using the discrete element method (circle type element) and Finite Element Method (FEM). The experimental tests used for the laboratory tensile strength measurement is the Compressive-to-Tensile Load Conversion (CTLC) device. In this paper, the failure process including the cracks initiation, propagation and coalescence studied and then the direct tensile strength of the UHPC specimens measured by the novel apparatus i.e., CTLC device. For this purpose, the UHPC member (each containing a central hole) prepared, and situated in the CTLC device which in turn placed in the universal testing machine. The direct tensile strength of the member is measured due to the direct tensile stress which is applied to this specimen by the CTLC device. This novel device transferring the applied compressive load to that of the tensile during the testing process. The UHPC beam specimen of size 150 × 60 × 190 mm and internal hole of 75 × 60 mm was used in this study. The rate of the applied compressive load to CTLC device through the universal testing machine was 0.02 MPa/s. The direct tensile strength of UHPC was found using a new formula based on the present analyses. The numerical simulation given in this study gives the tensile strength and failure behavior of the UHPC very close to those obtained experimentally by the CTLC device implemented in the universal testing machine. The percent variation between experimental results and numerical results was found as nearly 2%. PFC2D simulations of the direct tensile strength measuring specimen and ABAQUS simulation of the tested CTLC specimens both demonstrate the validity and capability of the proposed testing procedure for the direct tensile strength measurement of UHPC specimens.

A Comparison of Methods for the Detection of Outliers in Multivariate Data

Hadi, Ali-S.,Joo, Hye-Seon,Son, Mun-S. The Korean Statistical Society 1996 Communications for statistical applications and me Vol.3 No.2

Numerous classical as well as robust methods have been proposed in the literature for the detection of multiple outlier in multivariate data. The effectiveness and power of each of these methods have not been thoroughly investigated. In this paper we first reduce the vast number of outlier detection methods to a small number of viable ones. This reduction is based on previous work of other researches and on some theoretical arguments. Then we design and implement a Monte Carlo experiment for comparing these methods. The main goal of our study is to determine which methods are most powerful in the detection of multiple outlier and in dealing with the masking and swamping problems. The results of the Monte Carlo study indicate that two of the methods seem to hace better performances than the others for the detection of multiple outlier in multivariate data.

Experimental and numerical studies of the pre-existing cracks and pores interaction in concrete specimens under compression

Hadi Haeri,Vahab Sarfaraz,Zheming Zhu,Mohammad Fatehi Marji 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.5

In this paper, the interaction between notch and micro pore under uniaxial compression has been performed experimentally and numerically. Firstly calibration of PFC2D was performed using Brazilian tensile strength, uniaxial tensile strength and biaxial tensile strength. Secondly uniaxial compression test consisting internal notch and micro pore was performed experimentally and numerically. 9 models consisting notch and micro pore were built, experimentally and numerically. Dimension of these models are 10 cm *10 cm* 5 cm. the length of joint is 2 cm. the angularities of joint are 30°, 45° and 60°. For each joint angularity, micro pore was situated 2cm above the lower tip of the joint, 2 cm above the middle of the joint and 2 cm above the upper of the joint, separately. Dimension of numerical models are 5.4 cm*10.8 cm. The size of the cracks was 2 cm and its orientation was 30°, 45° and 60°. Diameter of pore was 1cm which situated at the upper of the notch i.e., 2 cm above the upper notch tip, 2 cm above the middle of the notch and 2 cm above the lower of the notch tip. The results show that failure pattern was affected by notch orientation and pore position while uniaxial compressive strength is affected by failure pattern.

The effect of particle size on the edge notched disk (END) using particle flow code in three dimension

Hadi Haeri,Vahab Sarfarazi,Zheming Zhu,Mohammad Fatehi Marji 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.6

In this study, the effect of particle size on the cracks propagation and coalescence or cracking pattern of the edge notched disc specimens are investigated. Firstly, calibration of PFC3D was performed using Brazilian experimental test output. Then micro parameters were used to build edge notched disc specimen. The horizontal wall of the assembly is let to move downward with a standard low speed of 0.016 m/s. The numerical results show that the tensile cracks are dominant failure pattern for the modeled discs. These tensile cracks initiate from the pre-existing notch tip and propagate parallel to the loading direction then interact with the upper boundary of the modeled specimen. As the size of the balls (ball diameter) decrease the number of tensile cracks increase. The tensile fracture toughness of the samples also decreases as the particle size increases. Understanding the crack propagation and crack coalescence phenomena in brittle materials such as concretes and rocks is of paramount importance in the stability analyses for engineering structures such as rock slopes, underground structures and tunneling.

Groundwater Inflow Assessment to Karaj Water Conveyance Tunnel, Northern Iran

Hadi Farhadian,Arash Nikvar Hassani,Homayoon Katibeh 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.6

In this paper, groundwater inflow into Karaj Water Conveyance (KWC) tunnel was estimated using analytical and numerical methods in 12 different sections of the tunnel length. Further, these sections were rated from groundwater hazard point of view by means of Site Groundwater Rating (SGR) factor. Comparing results show a reasonable accordance between observed water ingress rate and those various methods. Since, KWC tunnel is excavated in fractured rocks with a high level of anisotropy, analytical methods provided highly overestimated water inflow rate. Furthermore all SGR, analytical and numerical results, show high levels of water inflow from fault zones. Maximum water inflow into tunnel was computed as 0.0536 and 0.0432 lit/sec/m using analytical and numerical methods, respectively. Based on SGR method, 11 out of 12 sections in KWC tunnel length are found to be in “No Risk” class with groundwater inflow of less than 0.04 lit/sec/m which are in agreement with analytical and numerical seepage values and also with the observed inflow rate.