Optimization the inner product vector method and its application to structural health monitoring

Fast methods to identification and recognition of structural defects are important issues for the industry. In recent years, a growing interest has been on quick structural inspection to significantly reduce inspection’s cost and time, while minimizing the number of Non-Destructive Testing (NDT). Investigations on damage detection methods based on vibration monitoring have been developed in the last decade. This paper presents a study on Inner Product Vector (IPV) method. The IPV method is a new vibration based damage detection technique. In this method vibration responses are measured before and after damage occurrence. The vibration responses include the time domain acceleration (or displacement or velocity). The IPV method has the potential to significantly reduce costs by minimizing the need for NDT methods. For damage detection via the IPV method, a threshold should be selected for classifying the damaged and undamaged sections of a structure. Proper determination of the threshold value requires selection of Confidence Interval Factor (CIF). In this study, a new algorithm for the IPV method is suggested in which a new optimized model for damage detection is presented. Aforementioned optimized model can provide an accurate value for the CIF. To ascertain the exact CIF, the damage detection method is simulated. An accurate threshold makes the IPV method capable to accurately detect damages. The method has been verified by means of an FEM model as well as an experimental case study. The results show that the optimization process can be used as a reference to ascertain value for the CIF. The IPV method can be used as a Structural Health Monitoring (SHM) method, but it’s necessary to optimize the IPV method for each sample

The efficacy of O3, UV and UV/O3 on the removal of humic acids from water in a plug flow reactor

Background and Aims: Humic Acid (HA) is the most important combination of water humic materials. Removal of this compound leads to decreased production of chlorination by-products. This study set out with the aim of assessing the efficiency of O3, UV and UV/O3 in a plug-flow reactor in order to remove HA from water.Materials and Methods: The removal efficiency was assessed at three distinct steps through raw synthetic water samples containing specific concentrations of HA and treated water measurements of humic acid. Experiments were carried out in a laboratory scale plug-flow combined UV and ozonation system. The first question in this study sought to determine the compounded impact of ozone and UV on HA removal. The subsequent second and third questions in this research were to determine the separate effects of ozone andUV on the removal of target compound.Results: HA removal was slightly augmented in simultaneous presence of UV and ozone reaching 74.7% at initial HA concentration of 15 mg/L, pH 8, and reaction time of 25 min. However, on the question of separate effects of ozone and UV, this study found thatthe removal rate of HA, at similar situations, were 69% and 21%, respectively.Conclusion: Integrated application of UV and ozone outperformed conventional separate use of them in terms of HA removal. Higher removal efficiencies which achieved during ozone treatment, as compared with UV, might be due to higher oxidation power of ozone and OH radicals.Key words: Advanced Oxidation, UV, Ozonation, Humic Aci

Nonlinear Vibration Analysis of Axially Functionally Graded Microbeams Based on Nonlinear Elastic Foundation Using Modified Couple Stress Theory

In this study, a non-classical approach was developed to analyze nonlinear free and forced vibration of an Axially Functionally Graded (AFG) microbeam by means of modified couple stress theory. The beam is considered as Euler-Bernoulli type supported on a three-layered elastic foundation with Von-Karman geometric nonlinearity. Small size effects included in the analysis by considering the length scale parameter. It is assumed that the mass density and elasticity modulus varies continuously in the axial direction according to the power law form. Hamilton's principle was implemented to derive the nonlinear governing partial differential equation concerning associated boundary conditions. The nonlinear partial differential equation was reduced to some nonlinear ordinary differential equations via Galerkin's discretization technique. He's Variational iteration methods were implemented to obtain approximate analytical expressions for the frequency response as well as the forced vibration response of the microbeam with doubly-clamped end conditions. In this study, some factors influencing the forced vibration response were investigated. Specifically, the influence of the length scale parameter, the length of the microbeam, the power index, the Winkler parameter, the Pasternak parameter, and the nonlinear parameter on the nonlinear natural frequency as well as the amplitude of forced response have been investigated

Evaluation of effect changing temperature on lamb-wave based structural health monitoring

The purpose of this paper is to investigate the effect of temperature change on the Lamb wave-based SHM method. This study evaluates the Lamb wave method’s ability to detect damage to an AL2024-T3 sheet, assessed by a near-surface hole. Lamb waves are created via numerical simulation with the commercial Finite Element (FE) package ABAQUS. In this study, the Lamb wave-based SHM method using displacement responses is used. The results indicate that this method is able to detect a near-surface hole in the AL2024-T3 sheet as well as its location, with close approximation. Subsequently, the AL1100 sheet was investigated for changes in temperature from this method, which was evaluated over a temperature range of –200°C to 204°C. The results show that temperature change in the range of –200°C to 93°C has no effect on the displacement responses. However, the graphs related to temperature change of more than 149°C do not overlap with the reference temperature. Hence, it has been concluded that Lamb waves can be used as an SHM method in the temperature range of –200°C to 93°C without having to worry about the effects of temperature change on the results

بررسی کارآیی UV ،O3 و UV/O3 در راکتور با جریان قالبی جهت حذف اسید هیومیک از آب

ackground and Aims: Humic Acid (HA) is the most important combination of water humic materials. Removal of this compound leads to decreased production of chlorination by-products. This study set out with the aim of assessing the efficiency of O3, UV and UV/O3 in a plug-flow reactor in order to remove HA from water.Materials and Methods: The removal efficiency was assessed at three distinct steps through raw synthetic water samples containing specific concentrations of HA and treated water measurements of humic acid. Experiments were carried out in a laboratory scale plug-flow combined UV and ozonation system. The first question in this study sought to determine the compounded impact of ozone and UV on HA removal. The subsequent second and third questions in this research were to determine the separate effects of ozone andUV on the removal of target compound.Results: HA removal was slightly augmented in simultaneous presence of UV and ozone reaching 74.7% at initial HA concentration of 15 mg/L, pH 8, and reaction time of 25 min. However, on the question of separate effects of ozone and UV, this study found that the removal rate of HA, at similar situations, were 69% and 21%, respectively.Conclusion: Integrated application of UV and ozone outperformed conventional separate use of them in terms of HA removal. Higher removal efficiencies which achieved during ozone treatment, as compared with UV, might be due to higher oxidation power of ozone and OH radicals.زمينه و هدف: درمیان مواد هیومیکی موجود در آب، اسید هیومیک بعنوان مهمترین ترکیب پیش‌ساز تشکیل محصولات جانبی ناشی از کلرزنی مطرح است. حذف اسید هیومیک، کاهش تولید ترکیبات جانبی ناشی از کلرزنی آب را بدنبال دارد. این مطالعه با هدف بررسی کارآیی UV ،O3 و UV/O3 در راکتور با جریان قالبی جهت حذف اسید هیومیک از آب انجام گرفت. مواد و روش‌ها: این مطالعه در سه مرحله برروی نمونه‌های سنتتیک آب حاوی غلظت‌های مشخص از اسید هیومیک در یک سیستم تلفیقی UV و ازن‌زنی با جریان قالبی در مقیاس آزمایشگاهی انجام گردید. در مرحله اول مطالعه، تاثیر ازن و UV با هم و در مراحل دوم و سوم، تاثیر ازن و UV به طور جداگانه در حذف اسید هیومیک مورد بررسی قرار گرفت.    يافته‌ها: نتایج نشان داد با غلظت اولیه اسید هیومیک 15 میلی‌گرم در لیتر، pH برابر 8 ، غلظت ازن تزریقی 5/3 گرم در ساعت، زمان واکنش 25 دقیقه و با حضور UV و ازن، درصد حذف اسید هیومیک 7/74% بدست آمد. این در حالی است که در شرایط مشابه و با کاربرد ازن و UV به تنهایی، به ترتیب 69 و 21 درصد حذف اسید هیومیک حاصل شد.   نتيجه گيري: این مطالعه نشان داد که کاربرد ترکیبی UV/O3، کاراتر از بکارگیری ازن و UV به تنهایی می‌باشد. ازن راندمان بیشتری نسبت به UV در حذف اسید هیومک دارد که می‌تواند بخاطر قدرت اکسید کنندگی بالای ازن و رادیکال‌های OH باشد

Nonlinear Dynamic Response of an Axially Functionally Graded (AFG) Beam Resting on Nonlinear Elastic Foundation Subjected to Moving Load

In recent years, structures made of Functionally Graded materials (FGMs) are used in industries due to the continuously compositional variation of the constituents in FGMs along different directions. In order to develop FGMs, nonlinear vibration analysis to study dynamic behavior is needed. This study proposes nonlinear vibration analysis of a simply supported axially functionally graded (AFG) beam subjected to a moving harmonic load as an Euler-Bernoulli beam utilizing Green’s strain tensor. Axial variation of material properties of the beam is based on the power law. The governing equations of motion are derived via Hamilton’s principle. The Galerkin’s method is implemented to reduce the nonlinear partial differential equations of the system to a number of nonlinear ordinary differential equations. He’s variational method is applied to obtain approximate analytical expressions for the nonlinear frequency and the nonlinear dynamic response of the AFG beam. The effect of some parameters such as the power index and stiffness coefficients, among others, on the nonlinear natural frequency has been investigated. The influence of above mentioned parameters as well as the velocity of the moving harmonic load on the nonlinear dynamic response has been studied. The results indicate that these parameters have a considerable effect on both nonlinear natural frequency and response amplitude

Barriers to Effective Nurse- Patient Communication from Perspective of Nurses Employed in Educational Hospitals of Ilam

Background and Aims: Effective communication between the nurse and the patient is one of the important factors in providing high quality nursing cares. Therefore, identifying barriers to effective communication is necessary. The aim of this study was to determine the Barriers to effective nurse- patient communication from perspective of nurses employed in educational hospitals of Ilam.Methods: This Descriptive and analytical study was conducted during the summer of 2012 in Ilam city. 80 nurses in three educational hospitals affiliated with the Ilam Medical University were selected by random sampling method. Data were collected using a 30-item questionnaire. Reliability was calculated by Cronbach's alpha (r=0 93). In order to analyze the data, SPSS statistical software version 16, T-test and ANOVA were used.Results: The results of this study showed that in this study %43.8 of the participants were female. Regarding individual and social factors, job specifications, clinical situation of patients, and environmental factors irritability of nurses, nurses' physical and mental fatigue, and presence of a family care provider and lack of in-service training in communication skills were important barriers to the communication respectively.Conclusion: Effective communication is an important factor in obtaining positive results from treatment, reducing stress and increasing patients' satisfaction of medical care. Since the communication is an inevitable aspect of nursing cares, to enhance the nurse-patient communication it is necessary to obstacles mentioned above be resolved by managers.*Corresponding Author: Iman Mohammadi, Department of Nursing, Faculty of Nursing and Midwifery, Student Research Committee of Ilam University of Medical Sciences, Ilam, Iran.Email: [email protected]

Modal Parameter Extraction of a Huge Four Stage Centrifugal Compressor Using Operational Modal Analysis Method

<div><p>Abstract In recent years, modal analysis has become one of the essential methods for modification and optimization of dynamic characteristics of engineering structures. This is the first published study to identify modal parameters of a complex four-stage centrifugal compressor using Operational Modal Analysis (OMA). Vibrational response was measured continuously with sampling frequency of 44100(Hz) by four noncontact eddy current sensors. Applied loads in actual working condition during compressor’s operation were considered as excitation forces. In this study, modal parameters were extracted and compared using various OMA methods, including Frequency Domain Decomposition (FDD), Enhanced Frequency Domain Decomposition (EFDD) and Stochastic Subspace Identification (SSI). PULSETM commercial software as well as an in-house MATLAB code employed to data analysis. The results show that SSI method has a higher accuracy compared to FDD and EFDD methods. However, FDD shows better results when system damping is low in one of the modes.</p></div