Root Mean Square Deviation Index Research Articles

Expectation Disconfirmation, Ideal Point and Kano Models of Customer Satisfaction: A Comparison

This article compares three customer satisfaction models: expectation disconfirmation, ideal point, and Kano. It depicts the details of the three types of satisfaction stochastic models. A beauty shop's e-commerce database is used as empirical data for parameter estimates and model comparisons. The model calibration uses both root-mean-square deviation (RMSD) and the Chi-square test. The results demonstrate that the expectation disconfirmation model has the maximum fitness in the RMSD index, but the lowest goodness of fit in the Chi-square test. In contrast, the ideal point model produces opposite findings on the RMSD index and the Chi-square test. The expectation model, which has a larger number of parameters than the other two models, can be used for elastic changes to explain varied situational elements of pleasure, but it also requires more data to be stable. However, the ideal point model has a simpler structure than the other two models. There is only one parameter to estimate, which makes it easy to apply. However, it is less accurate than the other two models when measuring dynamic satisfaction.

Application of wavelet transform techniques for corrosion assessment of embedded rebars in RC elements using electromechanical impedance

Corrosion of steel reinforcement embedded in concrete significantly influences the integrity and durability attributes of reinforced concrete structures. Monitoring of the early age corrosion of the reinforcements can contribute to an effective planning of structural maintenance and restoration. This paper demonstrates an innovative approach of monitoring the rate of corrosion (mass loss due to corrosion) of steel bars embedded in concrete by capturing conductance signature using Piezoelectric sensors (PZT) by Electromechanical Impedance Technique. In the recent times Wavelet Transform (WT) based different techniques have been proved to be promising techniques for different structural health monitoring assessment. This study aims to comprehensively use the WT techniques based on EMI signals to assess the corrosion levels in the reinforcement embedded in RC members. Specifically, the study focuses on capturing the progression of corrosion levels using the RMSD index derived from the DWT, CWT and WPT analysis of conductance signatures. WT techniques provides energy values of conductance signatures. Energy level of the signatures decreases with the increase of corrosion levels and deviation of energy level between current and pristine stage is measured using statistical index Root Mean Square Deviation (RMSD). Robust relationship between the RMSD index and the corrosion mass loss ratio through nonlinear curve fitting have been derived and presented using data captured from the 48 specimens of concrete cylinders with embedded reinforcement. At last, the comparison between the actual mass loss ratio and the predicted mass loss ratio derived from these techniques have been made for the validation of the proposed relation of predicted mass loss due to corrosion.

Experimental Study on Damage Evolution Characteristics of Concrete under Impact Load Based on EMI Method

In this paper, the damage evolution characteristics of C50 concrete under impact load were studied, based on the electro-mechanical impedance (EMI) technique. A parallel test was conducted based on the internal relationship between EMI technology and a resonant frequency test to verify the sensitivity and accuracy of EMI technology. In addition, another mechanical test was conducted on specimens with different levels of damage to establish the empirical relationship between the degree of damage and the mechanical properties of concrete. The degrees of damage were discussed by calculating the root mean square deviation (RMSD) index. Results illustrated that the damage changes of concrete can be well monitored by PZT patches. Based on the evolutionary characteristic of the RMSD index, worrying information can be obtained before the destruction of the concrete. On the other hand, mechanical test results indicated that the value of the RMSD was correlated with the splitting tensile strength of the concrete specimens; therefore, it can be used as a reference to evaluate and predict the performance of concrete.

An optimized data fusion strategy for structural damage assessment using electromechanical impedance

This paper proposes a new sensor network optimized data fusion approach for structural health monitoring of metallic structures using electromechanical impedance (EMI) signals. The integrated approach used to fuse common healthy state baseline model based damage detection, quantification and classification in EMI technique. Towards this, the principal component analysis (PCA) is carried out and corresponding the root mean square deviation (RMSD) index is calculated to study the information of piezoelectric transducer’s impedance (|Z|), admittance (|Y|), resistance (R), and conductance (G) in the frequency domain. A new optimized data fusion approach is proposed which was realized at the sensor level using the PCA as well as at the variable level using self-organizing maps (SOMs). The SOM comparative studies are performed using the Q-statistics (Q index) and the Hotelling’s T2 statistic (T index). The proposed methodology is tested and validated for an aluminum plate with multiple drilled holes with variable size and locations. In the process, a centralized data-fused baseline eigenvector is prepared from a healthy structure and the damage responses are projected on this baseline model. The statistical, data-driven damage matrices are calculated and compared with the RMSD index and used in a fusion based data classification using SOM. The proposed method shows robust damage sensitivity for hole locations and hole enlargement irrespective of the wide frequency range selection, and the selected frequency range contains the resonant frequency range.

Numerical and experimental investigation of electro-mechanical impedance based concrete quantitative damage assessment

This paper presents a numerical and experimental investigation of the concrete quantitative damage assessment using the smart aggregate (SA) sensor based on the electro-mechanical impedance method. In the numerical simulation, a concrete cube finite element model with an embedded SA sensor is established using concrete damaged plasticity constitutive model to simulate the damage process under uniaxial compression. The concrete damage degree is evaluated using the conductance signatures of the embedded SA sensor and damage volume ratio (DVR). In the experimental study, three concrete cubes are casted and subjected to compressive loading. The experimental study verifies the numerical simulation model by comparing the root mean square deviation (RMSD) indices of conductance signals. Furthermore, the DVR is proposed as an effective damage evaluation index. The relationship curve between the DVR and the RMSD is fitted. The results illustrate that the RMSD index of the SA sensor and the DVR of the concrete have a linear relationship. The level of concrete damage can be quantitatively evaluated by RMSD index according the relationship between the RMSD and DVR.

Electromechanical impedance (EMI) measurements to infer features from the grinding process

This paper discusses the correlations between the electromechanical impedance (EMI) technique and grinding parameters. The EMI technique applied in grinding is novel and has the advantage of employing cheaper equipment and requiring a simpler monitoring system when compared to traditional techniques, such as acoustic emission. Experimental tests were conducted in a controlled environment to isolate the variables of interest, and real and imaginary parts of the impedance were investigated for several frequency bands. Strong correlations among EMI and equivalent chip thickness, roughness, and microhardness of the workpiece, as well as power signals, were found. The RMSD (root-mean-square deviation) index for the real part of the signature in the band 80–85 kHz showed good correlation with roughness and power, while the CCDM (correlation coefficient deviation metric) index for the imaginary part of 50–55 kHz showed good correlation with microhardness. Those correlations allow the user to infer information about the grinding process through indirect monitoring.

Instantaneous monitoring the early age properties of cementitious materials using PZT-based electromechanical impedance (EMI) technique

The use of piezoelectric materials based Electromechanical Impedance (EMI) technique for monitoring the hydration of cementitious materials has caught much attention recently. However, very few literatures have explored the feasibility of using this method on monitoring the stiffness development and compressive strength gain at the very early age properties (4th–8th h) of cementitious materials. This research serves as a comprehensive study to verify the reliability of using lead zirconate titanate (PZT) based EMI method in monitoring the compressive strength gain and elastic modulus of mortar at both very early age (4th–8th h) and early age (1st, 3rd, and 7th day). Extensive experiments and data analysis have been done on ten different mixes with various water-to-cement ratio and Type I & III cement. The EMI signatures are measured for each sample at the period of interest, and post-processed with three statistic model including the root mean square deviation (RMSD), correlation coefficient deviation (CCD), and mean absolute percentage deviation (MAPD) as indices. To examine the correlation and linearity between the compressive strength/elastic modulus obtained via conventional cubic testing using ASTM C109 and the EMI indices, a linear least square regression analysis is performed. As the authors postulated, all the mixes display a good linear correlation of R2. Among all three statistical indices, RMSD index is proved as the most accurate statistical index on strength gain monitoring of cementitious materials. The results indicated the feasibility of using piezoelectric-based EMI method for monitoring the cementitious material’s strength gain at very early age, regardless the concrete mix design.

Damage Evaluation of Concrete Column under Impact Load Using a Piezoelectric-Based EMI Technique.

One of the major causes of damage to column-supported concrete structures, such as bridges and highways, are collisions from moving vehicles, such as cars and ships. It is essential to quantify the collision damage of the column so that appropriate actions can be taken to prevent catastrophic events. A widely used method to assess structural damage is through the root-mean-square deviation (RMSD) damage index established by the collected data; however, the RMSD index does not truly provide quantitative information about the structure. Conversely, the damage volume ratio that can only be obtained via simulation provides better detail about the level of damage in a structure. Furthermore, as simulation can also provide the RMSD index relating to that particular damage volume ratio, the empirically obtained RMSD index can thus be related to the structural damage degree through comparison of the empirically obtained RMSD index to numerically-obtained RMSD. Thus, this paper presents a novel method in which the impact-induced damage to a structure is simulated in order to obtain the relationship between the damage volume ratio to the RMSD index, and the relationship can be used to predict the true damage degree by comparison to the empirical RMSD index. In this paper, the collision damage of a bridge column by moving vehicles was simulated by using a concrete beam model subjected to continuous impact loadings by a freefalling steel ball. The variation in admittance signals measured by the surface attached lead zirconate titanate (PZT) patches was used to establish the RMSD index. The results demonstrate that the RMSD index and the damage ratio of concrete have a linear relationship for the particular simulation model.

Impedance based bolt pre-load monitoring using piezoceramic smart washer

Bolted connection is widely used in mechanical and civil engineering; however, in some cases, bolt looseness may cause catastrophic consequences. Bolt pre-load monitoring in real time can help to ensure the safety of component connections and durability of the entire steel structure. Previous research has demonstrated that a ‘smart washer (SW)’ fabricated by embedding a piezoceramic transducer into two flat metal rings could effectively detect the pre-load looseness of a bolted connection. The active sensing method, in which two SWs are necessary, was used in the previous research. In this research, an electro-mechanical impedance (EMI) method enabled by one ‘SW’ was developed to investigate the pre-load condition of a bolted connection. Since the installed SW is directly subjected to the same axial pre-load as that on the bolt, the piezoceramic SW with the EMI technique is uniquely suited for pre-load monitoring of a bolted connection. The pre-load reduction is directly reflected by the EMI of the piezoceramic SW. In particular, a decrease of the pre-load on a bolt connect results in the reduced of its resonant frequency, which can be revealed by the real part of the impedance. In addition, the root mean square deviation (RMSD) of the impedance signals was employed as an index to evaluate the bolt looseness degree. For the experimental study, a bolted connectional specimen with a piezoceramic SW was fabricated and investigated. In the experiment, eleven cases of different pre-loads on the bolt were studied. Experimental results clearly show that with the decrease of the bolt pre-load, the resonant frequency of the bolt joint also decreased, as reflected by the impedance of piezoceramic SW. In addition, experimental results demonstrated that the SW with the EMI based RMSD index can monitor bolt pre-load.

Sensitivity of embedded active PZT sensor for concrete structural impact damage detection

Lead zirconate titanate (PZT) actuator/sensor is generally surface-bonded to structure in the electromechanical impedance (EMI) technique for structural health monitoring. However, in consideration of fragility and fugitiveness of surface-bonded PZT patch, it may lose serviceability when external impact happens especially in real-life applications. This paper covered the sensitivity of a new kind of embedded active PZT sensor in structural impact damage detection through theoretical and experimental analysis. Firstly, a new embedded 2D electromechanical impedance model was formulated, in which the PZT patch can be protected from external impact or disturbance. The proposed model was verified by experimental result of testing a manufactured embedded PZT sensor. Then the embedded PZT sensors were qualitatively compared with surface-bonded ones in the experiment of detecting a concrete beam which was damaged by successively knocking off concrete covers. Finally, the effectiveness of embedded PZT sensor in quantification on structural damage was investigated by using slope-based root mean square deviation (RMSD) index. Moreover, a new baseline-changeable RMSD index was also proposed to evaluate the impact effect for the two types of PZT sensor. It was found that the embedded PZT sensor can effectively filter out the impact effect in structural damage indication and quantification, which benefits the accurate evaluation on structural damage.

برآورد مقایسهای پارامترهایL*a*b* از دادههای RGB عکس دیجیتالی با استفاده از دستگاه سنجش رنگ IMG-Pardazesh

رنگ و ویژگی های ظاهری سطح یک ماده غذایی به‌عنوان اولین پارامترهایی هستند که توسط مصرف‌کننده مورد قضاوت قرار گرفته و مبنای رد یا قبول آن ماده می‌باشد. در این پژوهش کارآیی دستگاه IMG-Pardazesh در خصوص اندازه‌گیری رنگ در مقایسه با سیستم CIE L*ab، سیستم Hunter lab و سیستم استاندارد Patch Tool مورد ارزیابی قرار گرفت. بر این مبنا میزان عددی همبستگی (R2) موجود بین سه پارامتر L*، a* و b* بدست آمده از دستگاه IMG-Pardazesh در مقایسه باسیستم CIE L*ab به ترتیب معادل 996/0، 998/0، و 980/0 و در مقایسه با داده‌های Hunter lab معادل 983/0، 981/0، و 871/0 و با داده های نرم افزار Patch-color دارای میزان همبستگی (R2) معادل 935/0، 881/0 و 953/0 بود. در خصوص دستگاه اندازه‌گیری رنگ IMG-Pardazesh از بین ارزش عددی پارامترهای رنگ L*a*b*، و مقایسه آن با داده‌های سیستمCIE L*ab کاملا مشهود است که شاخص خطای جذر میانگین مربعاتRMSD در تمامی پارامترها با اختلاف جزئی کمتر بوده و در مقایسه با سیستم Hunter lab به جز پارامتر a در سایر پارامترها دارای ارزش عددی بسیار پایین‌تری بود. به‌علاوه محاسبه خطای نرمال شده‌ی میانگین‌ها نشان‌دهنده وجود خطای به مراتب بالاتر در تمامی پارامترها در سیستم CIE L*ab و خطای بسیار بالاتر در دو پارامتر L* و b* در سیستم Hunter lab می‌باشد. نتیجه اینکه بر مبنای این شاخص نیز می‌توان پی برد که دستگاه IMG-Pardazesh از میزان خطای کمتری در برآورد پارامترهای رنگ در مقایسه با سایر سیستم‌ها برخوردار می‌باشد.

Application of piezoceramic transducers for 3D Impedance modelling in damage assessment of plate

Cost-effective and reliable damage detection models are crucial for successful monitoring of any ancient or modern age engineering structure. Piezoceramic transducers (PZT) based electromechanical impedance (EMI) method is emerging as a promising alternate for conventional structural health monitoring (SHM) of various structures. The PZTs are usually surface bonded and then excited in the presence of electric field to a desired frequency range. The excitations result in prediction of unique frequency dependent electromechanical (EM) admittance signature. Any change in the signature during the monitoring period indicates dis-integrity in the structure. However, apart from locating damages, the increase in severity has to be predicted on time to avoid collapse of the entire structure. This paper presents such a model which had effectively predicted the severity of damages along two principle directions. This was achieved by experimental damage study on plates and subsequent verification by semi numerical 3D model. Statistical root mean square deviation (RMSD) index was used for evaluating the damages made on plates. A new frequency proximity index (FPI) was also introduced to measure the effectiveness of the model. RMSD measures the changes in height of peaks of signature and FPI scales the frequency spectrum of signature. Thus results of RMSD index and FPI are used as complementary to each other to study damage propagation in a structure.

Smart piezoelectric transducers for in situ health monitoring of concrete

This paper presents the results of applying a non-parametric technique to the detection ofthe presence of damage and the monitoring of damage progression in concrete.The electromechanical impedance method using smart piezoceramic materialis utilized in this study. The smart piezoelectric lead-zirconate-titanate (PZT)transducers bonded onto the structures are used to actively provide the localexcitation and simultaneously sense the structural dynamic response in high frequencyband. The frequency-dependent electric admittance signatures of the piezoelectrictransducer are compared with the baseline signatures to determine the statusof the health of structures. The damage is quantified by the root-mean-squaredeviation (RMSD) index. The correlation of the RMSD index with the location andextent of damage is investigated. In this paper, two sets of experimental testsare performed on the concrete beams instrumented with PZT transducers. Thefindings summarized from the experimental results are confirmed by a series ofnumerical simulations using finite element analysis. The experimental and numericalresults demonstrate the suitability of using the smart PZT transducers for in situhealth monitoring of structural integrity in civil infrastructures using concrete.