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Highlights • The requirements for testing accuracy of the wideband voltage dividers are discussed. • The conditions having influence on ratio error and phase displacement are analyzed. • It is explained why the course of frequency characteristics depends from applied voltage. • It is shown that leakage current should be determined to provide proper level of insulation. • Proposed zero comparative method ensures accuracy of the divider for rated input voltage. Abstract The general concerns of the studies presented in this article are determination of the requirements and development of the alternative indirect method for testing transformation accuracy of distorted voltages and higher frequency signals by the wideband resistive-capacitive voltage dividers. The increase of the rms value of the input voltage causes increase of the internal temperature and the probability of malfunction, including initiation of the partial discharges, additionally increased with frequency of the higher harmonics. Changes of these conditions may cause considerable variations of the equivalent capacitance and resistance of the wideband voltage dividers. Therefore, their testing with decreased rms value of distorted input voltage, as permissible by the standard IEC 61869-11, may result in determination of significantly different frequency characteristics of ratio error and phase displacement, than it is for rated conditions. In order to ensure transformation accuracy for rated input voltage of the wideband voltage divider the zero comparative method may be used. Applied rms value of voltage to each part of the wideband voltage divider under construction must result from its rated input voltage. Developed procedure provides conditions needed to obtain rated equivalent capacitance/resistance of each part of the wideband voltage divider during its development. This ensure its required transformation accuracy for rated input voltage. However, to preserve the proper level of its insulation to ground the test to exclude additional increase of the leakage current with increase of the input voltage must be made. The principle of application of proposed idea is verified by determination of the frequency characteristics of ratio error and phase displacement of tested wideband voltage dividers for their rated input voltage. Therefore, they may be used as a reference voltage source for testing transformation accuracy of voltage transformers and other dividers. [ABSTRACT FROM AUTHOR]

Human-induced vibration has become a serious serviceability problem due to the larger opening of girder, lighter floor systems and longer spans designed and used in practice. Vibration tests were undertaken in laboratory to research the vibrational characteristics of the arch pre-stressed concrete truss (APT) system spanning 16.0 m. Results from ambient vibration, impulse excitations (heel-drop and jumping) and steady-state incentives (walking and running) were presented. Dynamic characteristics such as natural frequencies, damping ratios, mode shapes and acceleration responses were studied and checked against the existing codes. Experimental results show that the investigated APT girder possesses high fundamental frequency and low damping ratio. Moreover, the perception factors based on the root-mean-square acceleration, vibration dose value (VDV) and psychological comfort data were obtained. Lastly, the threshold accelerations and VDVs were suggested for evaluating the human-induced vibration. [ABSTRACT FROM AUTHOR]

On-line monitoring of beam quality requires non-invasive transverse phase space diagnostics. Emittance measurement is particularly challenging for high-intensity particle beams since space charge complicates the beam dynamics during measurement. Quadrupolar mode measurements have been empirically shown to provide information about the beam emittance, but so far only for small relative space charge effects, where the results depend on a linear theory. We present a quadrupolar mode measurement for space charge dominated beams with unsplit tunes using multi-turn resonant excitation. Results from experiments performed at the University of Maryland Electron Ring are compared to both analytic and numerical analysis of the rms envelope equations. [ABSTRACT FROM AUTHOR]

In this paper, the UWB channel characterization is presented considering stationary and mobility scenarios in an indoor environment based on data collected through time domain measurements. The measurement is conducted along indoor corridor using UWB pulses with the frequency range of 3.1–5.3 GHz. First, the path loss model, specifically the log normal shadowing model, is used to characterize the UWB channels for large-scale. It is found that the path loss exponents for the studied stationary and mobility scenarios are almost the same. Secondly, the time dispersion parameters of root mean square (RMS) delay spread and mean excess (MN-EX) delay are applied for characterizing the multipath delay dispersion, while the parameter defined as multipath gain (MG) is computed to measure the strength of multipath component of UWB channels. For both stationary and mobility scenarios, it is found that the average values of time dispersion parameters are also similar. However, the MG mean value in mobility case outperforms the one in stationary case by 2.6 dB. An extensive analysis is performed to understand the correlation of the time dispersion parameters of RMS delay spread and MN-EX delay; and the MG with transmitter (TX)-receiver (RX) separation distance. In addition, the interdependencies between the time dispersion and MG parameters are also studied. The analysis results showed that the correlations and independencies of the studied parameters closely depend on the physical structure of the studied indoor environment. It is shown that the correlation between RMS delay spread and MG varies between 0.06 and 0.84 based on the physical structure of environment. [ABSTRACT FROM AUTHOR]

In this paper, a 3-DOF (degree-of-freedom) model of quarter-car coupled with driver and cushion is used to derive an analytical formula, which can describe the driver RMS (root-mean-square) acceleration response with cars under random excitation generated by road irregularities. The study starts with the 3-DOF model. Based on the vehicle random vibration theory, using the residue theorem, the analytical formula of driver RMS acceleration considering cushion effects is obtained. Then, the driver RMS acceleration values calculated from the measured data and from the analytical formulae of the 3-DOF and the classical 2-DOF model are compared. The results show the analytical formula for the 3-DOF model provides a more reasonable approximation of the real response of the test car. Having obtained the analytical formula, the effects of vehicle parameters on driver RMS acceleration are studied. Finally, to provide critical foundations for the selection of the cushion damping, the optimal damping ratio of driver-cushion system is deciphered from the analytical formula. To uncover how each dynamic parameter effects the optimal damping ratio, the analysis of influencing factors is performed and some important conclusions are obtained. The derived analytical formula can be also conveniently used either during preliminary design or for other special purposes. [ABSTRACT FROM PUBLISHER]

The purpose of the Next Generation Safeguards Initiative (NGSI)–Spent Fuel (SF) Project is to strengthen the technical toolkit of safeguards inspectors and/or other interested parties. The NGSI–SF team is working to achieve the following technical goals more easily and efficiently than in the past using nondestructive assay measurements of spent fuel assemblies: 1) verify the initial enrichment, burnup, and cooling time of facility declaration; 2) detect the diversion or replacement of pins; 3) estimate the plutonium mass; 4) estimate decay heat; and 5) determine the reactivity of spent fuel assemblies. The differential die-away self-interrogation (DDSI) instrument is one instrument that was assessed for years regarding its feasibility for robust, timely verification of spent fuel assemblies. The instrument was recently built and was tested using fresh fuel assemblies in a variety of configurations, including varying enrichment, neutron absorber content, and symmetry. The early die-away method, a multiplication determination method developed in simulation space, was successfully tested on the fresh fuel assembly data and determined multiplication with a root-mean-square (RMS) error of 2.9%. The experimental results were compared with MCNP simulations of the instrument as well. Low multiplication assemblies had agreement with an average RMS error of 0.2% in the singles count rate (i.e., total neutrons detected per second) and 3.4% in the doubles count rates (i.e., neutrons detected in coincidence per second). High-multiplication assemblies had agreement with an average RMS error of 4.1% in the singles and 13.3% in the doubles count rates. [ABSTRACT FROM PUBLISHER]

In this study, a non-contact laser ultrasonic propagation imaging technique was applied to detect the damage of plate-like structures. Lamb waves were generated by an Nd:YAG pulse laser system, while a galvanometer-based laser scanner was used to scan the preliminarily designated area. The signals of the structural responses were measured using a piezoelectric sensor attached on the front or back side of the plates. The obtained responses were analyzed by calculating the root mean square (RMS) values to achieve the visualization of structural defects such as crack, corrosion, and so on. If the propagating waves encounter the damage, the waves are scattered at the damage and the energy of the scattered waves can be expressed by the RMS values. In this study, notch and corrosion were artificially formed on aluminum plates and were considered as structural defects. The notches were created with different depths and angles on the aluminum plates, and the corrosion damage was formed with different depths and areas. To visualize the damage more clearly, edge detection methodologies were applied to the RMS images and the feasibility of the methods was investigated. The results showed that most of the edge detection methods were good at detecting the shape and/or the size of the damage while they had poor performance of detecting the depth of the damage. [ABSTRACT FROM AUTHOR]

A high performance multi-channel time-to-digital converter (TDC) is implemented in a Xilinx Zynq-7000 field programmable gate array (FPGA). It can be flexibly configured as either 32 TDC channels with 9.9 ps time-interval RMS precision, 16 TDC channels with 6.9 ps RMS precision, or 8 TDC channels with 5.8 ps RMS precision. All TDCs have a 380 M Samples/second measurement throughput and a 2.63 ns measurement dead time. The performance consistency and temperature dependence of TDC channels are also evaluated. Because Zynq-7000 FPGA family integrates a feature-rich dual-core ARM based processing system and 28 nm Xilinx programmable logic in a single device, the realization of high performance TDCs on it will make the platform more widely used in time-measuring related applications. [ABSTRACT FROM AUTHOR]

During the dynamic simulation of cabin system, the damping parameters values of cabin suspension are the key factors. In previous work, for obtaining all the parameters of the cabin system of trucks for long distance transport, a parameters identification model was built by minimizing the error of the root-mean-square acceleration between the tested and the measured. However, the identification precision is not high. In this paper, according to the real cabin system of a heavy duty truck for short distance transport, a 3-DOF model of cabin system was built. Based on curve fitting method, a new identification model for damping parameters was established. At last, the bench test was done and the comparisons were conducted among the tested values, the values identified by the method built in this work, and those obtained by the method built in previous work. The results show that the model built and the method proposed are feasible, and the identification precision is higher than the previous work. [ABSTRACT FROM AUTHOR]

Triangular edge fairings are widely used and attached to the edges of rectangular box girder bridge decks to improve their aerodynamic responses. Bridge deck with edge fairing should be shaped efficiently to obtain optimum aerodynamic responses. In this paper, the shaping effect of a triangular edge fairing on aerodynamic behaviour of a bridge deck is presented. A wide range of top and bottom plate slopes is utilized to change the shape of the fairing. The unsteady RANS simulation with the k – ω -SST turbulence model is used to simulate the flow. The flow is discretized by the finite volume method with second-order accuracy in space and time. The mean and rms values of the force coefficients are evaluated and the after-body velocity fluctuations are plotted. The aerodynamic responses are tried to explain by means of pressure and velocity distributions around the bridge deck. A relative comparison of the aerodynamic responses of perforated and solid handrails is also presented. It is found that a lower aerodynamic response can be obtained by properly shaping the triangular edge fairing. [ABSTRACT FROM AUTHOR]

The results of measurements of the root-mean-square (rms) surface roughness of CdZnTe substrates by confocal microscopy (CM), atomic force microscopy (AFM), and X-ray reflectometry (XRR) are compared. It is determined that CM yields the highest rms roughness values, AFM assumes an intermediate position, and XRR measurements produce results that are an order of magnitude lower than those obtained with the use of the other two techniques. It is demonstrated that CM rms roughness values depend to a considerable extent on the type of the microscope objective used in experiments. Probable reasons for the discrepancy between the obtained results are discussed. [ABSTRACT FROM AUTHOR]

The paper presents an explicit damage visualization methodology in an aluminum plate through the application of wave propagation mechanics. The present work describes a series of experiments and a special signal processing technique, for speedy spatial visualization of damage in different sets of test specimens. Experiments on three aluminum specimens with lead zirconate titanate (PZT)-wave generator is described. Damages are simulated in the form of (1) attached mass, (2) missing bolts and altered boundary conditions and (3) drilled holes with different diameters, simulating both mass and stiffness reduction. Normal responses (out of plane flexure response) are measured with the Scanning Laser Doppler Vibrometer (SLDV). The time signals recorded during measurement have been utilized to calculate the values of Root Mean Square (RMS) response. To compensate for loss of amplitude, due to radially propagating and attenuating wave signal, time samples are weighted by a factor, termed as weighted RMS function. The novelty of the work is the development of an algorithm to compute and plot the RMS of the time function, weighted with the radial distance from the source of excitation and also factored which is termed as Radially Weighted and Factored_RMS (RWF_RMS). Hence the reflected wave from the damage is magnified and the effect of excitation source is diminished. This algorithm has been successfully implemented and tested with the experimental data and the damage location is isolated. The resolution of the technique is evaluated by expressing the size of defect as a fraction of the wavelength. Absolute Maximum Response (AMR), and contour maps for elegant damage detection are attempted. It is anticipated that the suggested approach enables fast and accurate identification of damage location. [ABSTRACT FROM AUTHOR]

Hand speed is particularly important in boxing both for protection against incoming blows and delivering blows. Sixteen amateur boxers (10 male, 6 female) with varying levels of experience from a boxing gym performed 20 jabs and 20 cross punches in air. The movement was recorded with a small wrist mounted accelerometer under the glove. The maximum velocity of each punch was determined from the RMS acceleration profile. The mean values of the jab maximal velocity was higher than the cross maximal velocity for 9 participants. The cross showed some dependence on reach (Spearman's correlation coefficient r = 0.57) and the jab dependence on experience (Spearman's correlation coefficient r = 0.56). The accelerometer technique has some promise for routine assessment of fist speed. [ABSTRACT FROM AUTHOR]

A new realization of RMS detector, employing two CCCIIs (controlled current conveyors), metal-oxide-semiconductor transistors and single grounded capacitor is present in this paper, without any external resistors and components matching requirements. The proposed circuit can be applied in measuring the RMS value of periodic, band-limited signals. The proposed circuit is very appropriate to further develop into integrated circuits. The errors related to the signal processing and errors bound were investigated and provided. To verify the theoretical analysis, the circuit PSpice simulations have also been included, showing good agreement with the theory. [ABSTRACT FROM AUTHOR]

Nowadays, using public transportation vehicles like metro in large cities are of significance, and exposure to whole-body vibration for the metro passengers is one of the physical contaminations. This paper is conducted with the aim of evaluating the passengers' convenience and health both in sitting and standing conditions. The present study was done on the passengers of lines 1, 2, and 4 of Tehran metro with the use of an oscillator and a SVAN958 analyzer of SVSNTEK Co., based on the measurement methods and guidelines of ISO 2631-1, 4. The average amounts of RMS acceleration while sitting was 1.1 m/s² with the standard deviation of 0.14 and while standing was 0.91 m/s² with the standard deviation of 0.05; estimated VDV amount while sitting and standing equaled 6.72 m/s² with the standard deviation of 1.26 and 6.48 m/s1.75 with the standard deviation of 0.96. Calculated RMS amounts generally fluctuated between level 3 (fairly unpleasant) and level 4 (unpleasant) of convenience evaluation scale, and total calculated VDV amounts for the sitting passengers was 1.1 m/s1.75, being more than the perceived dose of standing passengers. [ABSTRACT FROM AUTHOR]

This research work uses parameter variation techniques for calculating the set of vehicle parameters that result in the best ride comfort for the driver. Tractor semi-trailer vertical dynamic ride model is developed using 9 degrees-offreedom. The simulation of the model is conducted using MATLAB. The input to the system is a velocity amplitude function of the vertical road irregularities. Other inputs include the load conditions, vehicle speed and road conditions. The RMS vertical weighted acceleration at the driver's seat and at the centre of gravity of tractor and semi-trailer for different parameters of the vehicle are assessed for ride comfort analysis. [ABSTRACT FROM AUTHOR]

Abstract: Annoying vibrations caused by occupant walking is an important serviceability problem for long-span floors. At the design stage the floor׳s structural arrangement may frequently change to cater for the owner׳s varying requirements. An efficient and accurate approach for predicting a floor׳s acceleration response is thus of great significance. This paper presents a design-oriented acceleration response spectrum for calculating a floor׳s response given the floor׳s modal characteristics and a specified confidence level. 2204 measured footfall traces from 61 test subjects were used to generate 10s peak root-mean-square acceleration response spectra, on which a piecewise mathematical representation is based. The proposed response spectrum consists of three main parts: the first harmonic plateau ranging from 1.5 to 2.5Hz, the second harmonic plateau ranging from 3.0 to 5.0Hz and the descending part going with frequencies from 5.0 to 10.0Hz. The representative value of each plateau and the mathematical representation for the descending curve were determined statistically for different confidence levels. Furthermore, the effects of factors, such as floor span, occupant stride length, higher modes of vibration, boundary conditions and peak acceleration response, on the proposed spectrum have been investigated and a modification measure for each factor is suggested. A detailed application procedure for the proposed spectrum approach is presented and has been applied to four existing floors to predict their acceleration responses. Comparison between predicted and field measured responses shows that the measured accelerations of the four floors are generally close to or slightly higher than the predicted values for the 75 percent confidence level, but are all lower than the predicted values for the 95 percent confidence level. Therefore the suggested spectrum-based approach can be used for predicting a floor׳s response subject to a single person walking. [Copyright &y& Elsevier]

The synthetic aperture focusing technique (SAFT) can improve the image resolution of ultrasonic testing (UT) by applying a delay-and-sum (DAS) process to the received echoes. The drawback of using current SAFT to test a multi-layer medium is that the computation of delays is complicated and time-consuming. In this study, we propose a fast and simple method to calculate the approximated delays for using in SAFT to image flaws in multi-layer media without losing the resolution of the SAFT image. The approximated delays can be easily and quickly calculated by a hyperbolic time-distance relationship which is a function of the root-mean-square velocity ( V) of layers under circumstances of short lateral distance and horizontal layers. The error of approximated delays is very small when incorporating the amplitudes radiated from the transducer into the processing of SAFT. Two extreme experiments of immersion testing were carried out to test and evaluate the proposed method. The experimental results show that the proposed method is feasible. Thus, the approximated delays calculated by the V for using in SAFT to enhance the resolution of the scan image for testing the flaws in multi-layer medium are recommended. [ABSTRACT FROM AUTHOR]

Direct numerical simulations (DNS) are used here to study inertial particle acceleration statistics in the near-wall region of a turbulent channel flow. The study is motivated by observations in homogeneous isotropic turbulence (HIT) suggesting that when particle inertia increases, particle acceleration variance decreases due to both particle preferential accumulation and the filtering effect of inertia. In accordance with these studies, the present DNS shows that for increasing inertia, solid particle acceleration probability density functions (PDFs), scaled by the acceleration root-mean-square (RMS), depart from that of the fluid. The tails of these PDFs become narrower. However, in turbulent channel flow, as the Stokes number increases up to 5, the streamwise acceleration RMS in the near-wall region increases, while further increase of the Stokes number is characterized by the streamwise acceleration RMS decrease. In parallel, contrary to calculations in homogeneous isotropic turbulence, the conditional acceleration statistics of the fluid seen by the solid particle show that while the vertical and transverse acceleration RMS components remain close to the unconditional fluid acceleration, the longitudinal RMS component is remarkably higher in the near wall region. This feature is more pronounced as the Stokes number is increased. Additionally, the conditional acceleration PDFs overlap almost perfectly with the unconditional fluid PDFs, normalized by the acceleration RMS. The enhanced longitudinal acceleration variance of the fluid seen by the particles may be due to the spanwise alternation of high-and-low speed streaks. Depending on inertia, particles may respond to those fluid solicitations (experiencing an increase of the longitudinal acceleration RMS) or ignore the wall turbulent structures (presenting in that case a more homogeneous concentration). [ABSTRACT FROM AUTHOR]

The article presents a study which examines the harmonic and seismic response of tall building with tuned pendular inertial masses (TMs) and magnetorheological (MR) dampers in Chile. The study used a damping solution for building displacement demand reduction in the Chilean ground motions. It states that the effectiveness of TMs depend on the dynamic properties of structure as well as the frequency content of excitation. It says that TM-MR damper assembly promotes the lateral performance of the building through linear-quadratic regulator controllers (LQR). It mentions that the peak and root mean square (RMS) displacement values for the response of TM subjected to earthquake ground motions are improved.

The role of incoherent scattering in damping of transmitted radiation is studied on the basis of the statistical theory of X-ray scattering in a narrow rough collimator. Approximate expressions for the damping coefficients of waveguide modes are obtained, and damping associated with scattering is found to be proportional to the product of a root-mean-square amplitude of roughnesses by the correlation length. The effect of a considerable suppression of scattering near the absorption edges due to dispersion is predicted; this can also be observed from a decrease in the back-scattered beam intensity. The roughnesses not only reduce the radiation transmission by diffractive filters, but also adversely affect the selectivity of radiation filtering. The analytic expressions for the damping coefficients of waveguide modes make it possible to generalize the results to collimators with various properties of the surfaces. [ABSTRACT FROM AUTHOR]

Magneto-rheological elastomers (MREs) are used to construct composite structures for micro-vibration control of equipment under stochastic support-motion excitations. The dynamic behavior of MREs as a smart viscoelastic material is characterized by a complex modulus dependent on vibration frequency and controllable by external magnetic fields. Frequency-domain solution methods for stochastic micro-vibration response analysis of the MRE-based structural systems are developed to derive the system frequency-response function matrices and the expressions of the velocity response spectrum. With these equations, the root-mean-square (RMS) velocity responses in terms of the one-third octave frequency band spectrum can be calculated. Further, the optimization problem of the complex moduli of the MRE cores is defined by minimizing the velocity response spectra and the RMS velocity responses through altering the applied magnetic fields. Simulation results illustrate the influences of MRE parameters on the RMS velocity responses and the high response reduction capacities of the MRE-based structures. In addition, the developed frequency-domain analysis methods are applicable to sandwich beam structures with arbitrary cores characterized by complex shear moduli under stochastic excitations described by power spectral density functions, and are valid for a wide frequency range. [ABSTRACT FROM AUTHOR]

This report describes the development of a low cost, digital Micro Electro Mechanical System (MEMS) vibration meter that reports an approximation to the RMS acceleration of the vibration to which the vibration meter is subjected. The major mechanical element of this vibration meter is a cantilever beam, which is on the order of 500 µm in length, with a piezoresistor deposited at its base. Vibration of the device in the plane perpendicular to the cantilever beam causes it to bend, which produces a measurable change in the resistance of a piezoresistor. These changes in resistance along with a unique signal-processing scheme are used to determine an approximation to the RMS acceleration sensed by the device. [ABSTRACT FROM AUTHOR]

M-plane GaN avalanche p-i-n photodiodes on low dislocation density freestanding m-plane GaN substrates were realized using metal-organic chemical vapor deposition. High quality homoepitaxial m-plane GaN layers were developed; the root-mean-square surface roughness was less than 1 Å and the full-width-at-half-maximum value of the x-ray rocking curve for (1010) diffraction of m-plane GaN epilayer was 32 arcsec. High quality material led to a low reverse-bias dark current of 8.11 pA for 225 μm2 mesa photodetectors prior to avalanche breakdown, with the maximum multiplication gain reaching about 8000. [ABSTRACT FROM AUTHOR]