• Title/Summary/Keyword: problem analysis

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Seismic response of 3D steel buildings with hybrid connections: PRC and FRC

  • Reyes-Salazar, Alfredo;Cervantes-Lugo, Jesus Alberto;Barraza, Arturo Lopez;Bojorquez, Eden;Bojorquez, Juan
    • Steel and Composite Structures
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    • v.22 no.1
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    • pp.113-139
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    • 2016
  • The nonlinear seismic responses of steel buildings with perimeter moment resisting frames (PMRF) and interior gravity frames (IGF) are estimated, modeling the interior connections first as perfectly pinned (PPC), and then as partially restrained (PRC). Two 3D steel building models, twenty strong motions and three levels of the PRC rigidity, which are represented by the Richard Model and the Beam Line Theory, are considered. The RUAUMOKO Computer Program is used for the required time history nonlinear dynamic analysis. The responses can be significantly reduced when interior connections are considered as PRC, confirming what observed in experimental investigations. The reduction significantly varies with the strong motion, story, model, structural deformation, response parameter, and location of the structural element. The reduction is larger for global than for local response parameters; average reductions larger than 30% are observed for shears and displacements while they are about 20% for bending moments. The reduction is much larger for medium- than for low-rise buildings indicating a considerable influence of the structural complexity. It can be concluded that, the effect of the dissipated energy at PRC should not be neglected. Even for connections with relative small stiffness, which are usually idealized as PPC, the reduction can be significant. Thus, PRC can be used at IGF of steel buildings with PMRF to get more economical construction, to reduce the seismic response and to make steel building more seismic load tolerant. Much more research is needed to consider other aspects of the problem to reach more general conclusions.

Optimum design and vibration control of a space structure with the hybrid semi-active control devices

  • Zhan, Meng;Wang, Sheliang;Yang, Tao;Liu, Yang;Yu, Binshan
    • Smart Structures and Systems
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    • v.19 no.4
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    • pp.341-350
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    • 2017
  • Based on the super elastic properties of the shape memory alloy (SMA) and the inverse piezoelectric effect of piezoelectric (PZT) ceramics, a kind of hybrid semi-active control device was designed and made, its mechanical properties test was done under different frequency and different voltage. The local search ability of genetic algorithm is poor, which would fall into the defect of prematurity easily. A kind of adaptive immune memory cloning algorithm(AIMCA) was proposed based on the simulation of clone selection and immune memory process. It can adjust the mutation probability and clone scale adaptively through the way of introducing memory cell and antibody incentive degrees. And performance indicator based on the modal controllable degree was taken as antigen-antibody affinity function, the optimization analysis of damper layout in a space truss structure was done. The structural seismic response was analyzed by applying the neural network prediction model and T-S fuzzy logic. Results show that SMA and PZT friction composite damper has a good energy dissipation capacity and stable performance, the bigger voltage, the better energy dissipation ability. Compared with genetic algorithm, the adaptive immune memory clone algorithm overcomes the problem of prematurity effectively. Besides, it has stronger global searching ability, better population diversity and faster convergence speed, makes the damper has a better arrangement position in structural dampers optimization leading to the better damping effect.

An efficient shear deformation theory for wave propagation in functionally graded material beams with porosities

  • Benadouda, Mourad;Atmane, Hassen Ait;Tounsi, Abdelouahed;Bernard, Fabrice;Mahmoud, S.R.
    • Earthquakes and Structures
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    • v.13 no.3
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    • pp.255-265
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    • 2017
  • In this paper, an efficient shear deformation theory is developed for wave propagation analysis in a functionally graded beam. More particularly, porosities that may occur in Functionally Graded Materials (FGMs) during their manufacture are considered. The proposed shear deformation theory is efficient method because it permits us to show the effect of both bending and shear components and this is carried out by dividing the transverse displacement into the bending and shear parts. Material properties are assumed graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents; but the rule of mixture is modified to describe and approximate material properties of the functionally graded beams with porosity phases. The governing equations of the wave propagation in the functionally graded beam are derived by employing the Hamilton's principle. The analytical dispersion relation of the functionally graded beam is obtained by solving an eigenvalue problem. The effects of the volume fraction distributions, the depth of beam, the number of wave and the porosity on wave propagation in functionally graded beam are discussed in details. It can be concluded that the present theory is not only accurate but also simple in predicting the wave propagation characteristics in the functionally graded beam.

Optimization of cables size and prestressing force for a single pylon cable-stayed bridge with Jaya algorithm

  • ATMACA, Barbaros;DEDE, Tayfun;GRZYWINSKI, Maksym
    • Steel and Composite Structures
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    • v.34 no.6
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    • pp.853-862
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    • 2020
  • In recent years, due to the many advantages cable-stayed bridges have often constructed in medium and long span. These advantages can be listed as an aesthetically pleasing appearance, economic and easy construction, etc. The main structural elements of cable-stayed bridges are listed as deck, pylon, cables and foundation. Perhaps one of the most vital and expensive of these structural elements is stay-cables. Stay-cables ensure the allowable displacement and distribution of bending moments along the bridge deck with prestressing force. Therefore the optimum design of the stay-cables and prestressing force are very important in achieving the performance expected from the cable-stayed bridges. This paper aims to obtain the stay-cables size and prestressing force optimization of the cable-stayed bridge. For this purpose, single pylon and fan type cable configuration Manavgat Cable-Stayed Bridge was selected as an example. The three dimensional (3D) finite element model (FEM) of the bridge was created with SAP2000. Analysis of the 3D FEM of the bridge was conducted under the different combined effects of the self-weight of the structural element, prestressing force of stay-cable and live load. Stay-cable stress and deck displacement were taken into account as constraints for the optimization problem. To optimize this existing bridge a metaheuristic algorithm named Jaya was used in the optimization process. 3D FEM of the selected bridge was repeatedly analyzed by using Open Applicable Programming Interface (OAPI) properties of SAP2000. To carry out the optimization process the developed program which integrates the Jaya algorithm and the required codes for calling SAP2000 is coded in MATLAB. At the end of the study, the total weight of the stay-cables was reduced more than 40% according to existing stay cables under loads taken into account.

Experimental study on hysteretic behavior of steel moment frame equipped with elliptical brace

  • Jouneghani, Habib Ghasemi;Haghollahi, Abbas
    • Steel and Composite Structures
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    • v.34 no.6
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    • pp.891-907
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    • 2020
  • Many studies reveal that during destructive earthquakes, most of the structures enter the inelastic phase. The amount of hysteretic energy in a structure is considered as an important criterion in structure design and an important indicator for the degree of its damage or vulnerability. The hysteretic energy value wasted after the structure yields is the most important component of the energy equation that affects the structures system damage thereof. Controlling this value of energy leads to controlling the structure behavior. Here, for the first time, the hysteretic behavior and energy dissipation capacity are assessed at presence of elliptical braced resisting frames (ELBRFs), through an experimental study and numerical analysis of FEM. The ELBRFs are of lateral load systems, when located in the middle bay of the frame and connected properly to the beams and columns, in addition to improving the structural behavior, do not have the problem of architectural space in the bracing systems. The energy dissipation capacity is assessed in four frames of small single-story single-bay ELBRFs at ½ scale with different accessories, and compared with SMRF and X-bracing systems. The frames are analyzed through a nonlinear FEM and a quasi-static cyclic loading. The performance features here consist of hysteresis behavior, plasticity factor, energy dissipation, resistance and stiffness variation, shear strength and Von-Mises stress distribution. The test results indicate that the good behavior of the elliptical bracing resisting frame improves strength, stiffness, ductility and dissipated energy capacity in a significant manner.

Predictors of Breast Cancer Screening Uptake: A Pre Intervention Community Survey in Malaysia

  • Dahlui, Maznah;Gan, Daniel Eng Hwee;Taib, Nur Aishah;Pritam, Ranjit;Lim, Jennifer
    • Asian Pacific Journal of Cancer Prevention
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    • v.13 no.7
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    • pp.3443-3449
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    • 2012
  • Introduction: Despite health education efforts to educate women on breast cancer and breast cancer screening modalities, the incidence of breast cancer and presentation at an advanced stage are still a problem in Malaysia. Objectives: To determine factors associated with the uptake of breast cancer screening among women in the general population. Methods: This pre-intervention survey was conducted in a suburban district. All households were approached and women aged 20 to 60 years old were interviewed with pre-tested guided questionnaires. Variables collected included socio-demographic characteristics, knowledge on breast cancer and screening practice of breast cancer. Univariate and multivariate analysis were performed. Results: 41.5% of a total of 381 respondents scored above average; the mean knowledge score on causes and risks factors of breast cancer was 3.41 out of 5 (SD1.609). 58.5% had ever practiced BSE with half of them performing it at regular monthly intervals. Uptake of CBE by nurses and by doctors was 40.7% and 37.3%, respectively. Mammogram uptake was 14.6%. Significant predictors of BSE were good knowledge of breast cancer (OR=2.654, 95% CI: 1.033-6.816), being married (OR=2.213, 95% CI: 1.201-4.076) and attending CBE (OR=1.729, 95% CI: 1.122-2.665). Significant predictors for CBE included being married (OR=2.161, 95% CI: 1.174-3.979), good knowledge of breast cancer (OR=2.286, 95% CI: 1.012-5.161), and social support for breast cancer screening (OR=2.312, 95% CI: 1.245-4.293). Women who had CBE were more likely to undergo mammographic screening of the breast (OR=5.744, 95% CI: 2.112-15.623), p<0.005. Conclusion: CBE attendance is a strong factor in promoting BSE and mammography, educating women on the importance of breast cancer screening and on how to conduct BSE. The currently opportunistic conduct of CBE should be extended to active calling of women for CBE.

Genes and SNPs Associated with Non-hereditary and Hereditary Colorectal Cancer

  • Nassiri, Mohammadreza;Kooshyar, Mohammad Mahdi;Roudbar, Zahra;Mahdavi, Morteza;Doosti, Mohammad
    • Asian Pacific Journal of Cancer Prevention
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    • v.14 no.10
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    • pp.5609-5614
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    • 2013
  • Background: Colorectal cancer is the third most common cancer in both men and women in the world and the second leading cause of cancer-related deaths. The incidence of colorectal cancer has increased in Iran in the past three decades and is now considered as a serious problem for our society. This cancer has two types hereditary and non-hereditary, 80% of cases being the latter. Considering that the relationship between SNPs with diseases is a concern, many researchers believed that they offer valuable markers for identifying genes responsible for susceptibility to common diseases. In some cases, they are direct causes of human disease. One SNP can increase risk of cancer, but when considering the rate of overlap and frequency of DNA repair pathways, it might be expected that SNP alone cannot affect the final result of cancer, although several SNPs together can exert a significant influence. Therefore identification of these SNPs is very important. The most important loci which include mutations are: MLH1, MSH2, PMS2, APC, MUTYH, SMAD7, STK11, $XRCC_3$, $DNMT_1$, MTHFR, Exo1, $XRCC_1$ and VDR. Presence of SNPs in these genes decreases or increases risk of colorectal cancer. Materials and Methods: In this article we reviewed the Genes and SNPs associated with non-hereditary and hereditary of colorectal cancer that recently were reported from candidate gene y, meta-analysis and GWAS studies. Results: As with other cancers, colorectal cancer is associated with SNPs in gene loci. Generally, by exploring SNPs, it is feasible to predict the risk of developing colorectal cancer and thus establishing proper preventive measures. Conclusions: SNPs of genes associated with colorectal cancer can be used as a marker SNP panel as a potential tool for improving cancer diagnosis and treatment planning.

Electrical Arc Detection using Convolutional Neural Network (합성곱 신경망을 이용한 전기 아크 신호 검출)

  • Lee, Sangik;Kang, Seokwoo;Kim, Taewon;Kim, Manbae
    • Journal of Broadcast Engineering
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    • v.25 no.4
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    • pp.569-575
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    • 2020
  • The serial arc is one of factors causing electrical fires. Over past decades, various researches have been carried out to detect arc occurrences. Even though frequency analysis, wavelet, and statistical features have been used, additional steps such as transformation and feature extraction are required. On the contrary, deep learning models directly use the raw data without any feature extraction processes. Therefore, the usage of time-domain data is preferred, but the performance is not satisfactory. To solve this problem, subsequent 1-D signals are transformed into 2-D data that can feed into a convolutional neural network (CNN). Experiments validated that CNN model outperforms deep neural network (DNN) by the classification accuracy of 8.6%. In addition, data augmentation is utilized, resulting in the accuracy improvement by 14%.

INVESTIGATION OF THE OPERATIONAL PRINCIPLE AND PARAMETRIC STUDY ON A DRY PASTE SEPARATOR EQUIPED WITH A ROTOR -II. CFD ANALYSIS (로터 장착 건식 미분 분리기의 작동원리 규명 및 파라미터 연구 - II. CFD 해석)

  • Park, S.U.;Kang, Y.S.;Kang, S.;Suh, Y.K.
    • Journal of computational fluids engineering
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    • v.20 no.4
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    • pp.81-92
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    • 2015
  • Construction waste mainly consists of concrete aggregates of various size. Improper handling of concrete waste would be a major environmental problem whereas its recycling would be both economically useful and environmentally friendly. Bigger concrete aggregates are crushed and converted to medium and fine particles to make them recyclable. An apparatus to separate the concrete aggregates by their size is thus needed for their effective recycling. In this work, segregation of concrete particles in air flows from a newly designed rotary separator having three stages of blades is simulated using a commercial software, ANSYS-CFX. Both 2-D and 3-D models with 360, 240 and 180 blades in each stage are considered. Fundamental mechanism of separation of particles(pase) and the effect of design parameters such as particle size, rotor speed, air flow rate etc. on the performance of the separator are investigated. Critical size of particles that can be separated by the developed separator is also presented in this work. Simulation results are overall in good agreement with data predicted from the theoretical model previously reported in the companion paper.

Relationship of TBL Component in Corporate Sustainable Management of Fashion Company with Company Evaluation and Brand Image (의류업체의 지속가능경영 TBL 구성요소와 기업평가 및 브랜드 이미지)

  • Na, Dongkyu;Lee, Jeongwon;Na, Youngjoo
    • Fashion & Textile Research Journal
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    • v.16 no.2
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    • pp.293-300
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    • 2014
  • Fashion companies confront to environmental problem and resource depletion and have to consider 'sustainability' into their management. Corporate sustainable management of company is explained as the model of Triple Bottom Line which is composed of economic, social and environmental elements, thus we wanted to adapt this model to the case of fashion companies and the purpose of this study is to investigate the relationship among the TBL elements which contain the economic, social and environmental responsibility, the evaluation on fashion company including the reliability, reciprocality and reputation of company, and the evaluation of brand image. We conducted the survey of questionnaire about 300 people in their 20's and performed statistical analysis. As a result, the elements of corporate sustainable management in fashion company are related to the company evaluation, and again company evaluation is correlated to the evaluation of brand image. Economic responsibility of fashion company is related with the reliability of company evaluation, social responsibility of fashion company with the reciprocality and reputation of company evaluation, and environmental responsibility is deeply related with reciprocality of fashion company's evaluation. The results of this study revealed the importance of corporate sustainable management of fashion companies, and the relationships in fashion industry are stronger than in other industry.