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This work examines the utilization of negative mass and negative stiffness principles to enhance the effectiveness of Dynamic Vibration Absorbers (DVAs) for vibration attenuation developed in structures. The proposed idealized model aims to reduce the amplitude of resonance and expand the frequency stopband range to achieve vibration reduction by attaching two parallel dynamic vibration absorbers to the primary system. By incorporating stiffness, mass, and damping ratio for each one of the absorbers and in the presence of harmonic excitation, it is possible to expand the frequency range in which vibration may be suppressed, leading to a substantial decrease in the maximum vibration amplitude of the primary system and the stroke length of the absorbers. The Nelder-Mead method is successfully used as an optimization tool to obtain the best selection of the absorbers' design parameters that assure the best vibration attenuation and frequency stopband. The results indicate a strong association between the change in frequency and the decrease in vibration. In the instance of frequency response, the vibration amplitude decreased by an average of 91.46% across all three modes of the whole system. Another optimal selection exhibited the most significant enhancement, achieving an average reduction in vibration amplitude of 97.06% across all three modes. Finally, the results indicate that the suggested lumped parallel architecture of the absorbers with precisely adjusted negative mass and negative stiffness characteristics along with the presented optimization method, can greatly improve the effectiveness of reducing vibrations in various applications. The results illustrate a direct relationship between shifts in frequency and vibration. If the value of the shift is greater than 1 the vibration is decreased, while less than 1 means the worst form of reducing such magnitude. The most notable drop off in amplitude occurred when averaging a simple drop off of up to 91.46% for all three patterns where frequency shifts by Y=2.008. [ABSTRACT FROM AUTHOR]

Soil plays a crucial role in human health through its impact on food and habitation. However, it often contains toxic heavy metals, with mercury being particularly hazardous when methylated. Currently, high-sensitivity, rapid detection of mercury is achievable only through electrochemical measurements. These measurements require pretreatment of the soil sample and the preparation of a calibration curve tailored to the sample's condition. In this study, we developed a method to determine the environmental standard value of mercury content in soil by significantly reducing the pretreatment process. Our approach involves analyzing current peaks from electrodeposition times using specific electrodes and solvent settings. This method demonstrates low error rates under low concentration conditions and can detect mercury levels as low as 0.5 ppb in soil leachate and reagent dilution series. This research facilitates the determination of low mercury concentrations in solutions containing various soil micro-compounds without the need for calibration curves. [ABSTRACT FROM AUTHOR]

The damping of spruce wood is analysed at different moisture content levels for the first three vibration modes of tangentially and radially vibrating samples. Two methods were used to determine the damping. The first was the vibration envelope fitting as an improved version of the well-known logarithmic decrement, and the second was the newer and recently increasingly used wavelet transform. Both methods showed that the damping of spruce wood first decreases and then increases with moisture content, with the damping in the first vibration mode being about 9% higher in the radial direction than in the tangential direction. In the second and third vibration modes, the damping in the tangential direction was higher than in the radial direction by about 10% and 8.8%, respectively. The measured damping factors from the envelope fitting had, on average, 15.9% higher values than those from the wavelet transform. It can be concluded from the results that the wavelet transform is more accurate for determining the damping factor, as it enables the decoupling of multi-degree of freedom systems if mode coupling is present. [ABSTRACT FROM AUTHOR]

Soil plays a crucial role in human health through its impact on food and habitation. However, it often contains toxic heavy metals, with mercury being particularly hazardous when methylated. Currently, high-sensitivity, rapid detection of mercury is achievable only through electrochemical measurements. These measurements require pretreatment of the soil sample and the preparation of a calibration curve tailored to the sample’s condition. In this study, we developed a method to determine the environmental standard value of mercury content in soil by significantly reducing the pretreatment process. Our approach involves analyzing current peaks from electrodeposition times using specific electrodes and solvent settings. This method demonstrates low error rates under low concentration conditions and can detect mercury levels as low as 0.5 ppb in soil leachate and reagent dilution series. This research facilitates the determination of low mercury concentrations in solutions containing various soil micro-compounds without the need for calibration curves.

The article presents the results of a study of a modal filter (MF) based on a microstrip line (MSL) with two side conductors grounded at both ends. For the first time, the quasi-static simulation and measurements of the filter are conducted with two devices, and the results are compared. Frequency dependences of |S11| and |S21| are measured and calculated in the range from 0 to 10 GHz. At the MF output, the time response to an ultrashort pulse (USP) was analyzed. It was experimentally proved that the performed quasi-static simulation was correct. The simulation and measurement results showed remarkable consistency. The proposed MF provides the protection of electrical circuits from USP by decomposing it into two pulses with the amplitudes that are more than three times smaller. This confirms that such MF obtained simply by adding to a MSL two passive conductors grounded at both ends can be used to create simple and cheap protection, for example, of critical radioelectronics against powerful intentional USP created by electromagnetic weapons. [ABSTRACT FROM AUTHOR]

Purpose: The feasibility of harvesting electrical energy from mechanical vibration is demonstrated in the thesis. In the technique, energy is harvested from simply supported beam vibration under a moving mass using a thin piezoelectric material. Design/methodology/approach: The structure is represented by a basic beam of length L that is supported at both ends and traversed by a moving mass M travelling at a constant velocity v. The Euler-Bernoulli differential equation describes its behaviour. The dynamic analysis of a beam is performed by using three moving masses of (35.61, 65.81, and 79.41) gr each travelling three uniform speeds of (1.6, 2 and 2.4) m/s. A differential equation of the electromechanical system is obtained by transforming the piezoelectric constitutive equation and solved numerically by MATLAB. Findings: The results indicate that the numerical and experimental values for the midpoint deflection of the beam and the piezoelectric voltage are very close. Research limitations/implications: Using the COMSOL programme, the proposed approach is checked by comparing results with data obtained by the finite element method (FEM). An experimental setup was also built and constructed to determine the voltage created by the piezoelectric patch and the beam response as a result of the mass travelling along the beam. Practical implications: The results show that the dynamic deflection, piezoelectric voltage, and piezoelectric energy harvesting all increase as the speed and magnitude of the moving mass increase. The harvesting power vs. load resistance curve begins at zero, increases to a maximum value, and then remains almost constant as the resistance is increased further. The optimal length of the piezoelectric patch was obtained to be 0.63 m. When the length of the beam increases, the resonant frequency decreases, and at the same time the harvested energy increases. However, increasing the beam thickness has the opposite effect; whereas raising the beam width does not affect the resonant frequency but decreases energy harvesting. Originality/value: The most essential point here is the need to have correctly built scale models. They can provide a substantial amount of information at a low cost, accommodate a variety of test settings, and aid in the selection and verification of the most effective analytical model to resolve the actual issue. [ABSTRACT FROM AUTHOR]

The damping of spruce wood is analysed at different moisture content levels for the first three vibration modes of tangentially and radially vibrating samples. Two methods were used to determine the damping. The first was the vibration envelope fitting as an improved version of the well-known logarithmic decrement, and the second was the newer and recently increasingly used wavelet transform. Both methods showed that the damping of spruce wood first decreases and then increases with moisture content, with the damping in the first vibration mode being about 9% higher in the radial direction than in the tangential direction. In the second and third vibration modes, the damping in the tangential direction was higher than in the radial direction by about 10% and 8.8%, respectively. The measured damping factors from the envelope fitting had, on average, 15.9% higher values than those from the wavelet transform. It can be concluded from the results that the wavelet transform is more accurate for determining the damping factor, as it enables the decoupling of multi-degree of freedom systems if mode coupling is present.

GNSS tomography is a method for the three-dimensional reconstruction of wet refractivity ( N w ) in a set of voxels, each covering a specific part of the troposphere. The substantial assumption is the homogeneity of atmosphere in each voxel in given time intervals, known as the time response of model. Determining the optimal time resolution is one of the existing challenges in the tomography of the Earth's atmosphere. We apply Empirical Orthogonal Functions (EOFs) to find an optimal time response for our tomographic model. To investigate our method, we compute the EOFs using the numerical atmospheric model that is available in our test area as the reference field on an already designed tomographic model. Using time resolutions of 30, 45, 60, 75, 90, 105 and 120 min, our EOF based method suggests the time periods of 60 to 75 and 75 to 90 min as the time response in the two days (a dry and a wet day) of our experiments, respectively According to our analysis, because of the quality of our reference field, it is not possible to expect similarities better than 85% for wet day and 93% for dry days in the scattering of the N w field between the reconstructed images and our reference model. [ABSTRACT FROM AUTHOR]

Spatial and temporal characteristics of a degenerate four-wave converter in a multimode waveguide with resonant nonlinearity in a scheme with counter-pumping waves are analyzed using the time response function and the point spread function. For single-mode pump waves with equal mode numbers, the dependences of the time response width on the waveguide length, the intensity of the first pump waves, and the mode number in the mode expansion of the object wave amplitude are obtained for the four-wave converter. The greatest contribution to the object wave amplitude is shown to be from the waveguide mode whose number coincides with the mode number of single-mode pump waves. For the stationary model, taking into account the spatial structure of the Gaussian pump wave leads to a monotonous decrease with a decrease in the pump beam width, followed by a constant value of the PSF module width. With single-mode pump waves with equal mode numbers, An increase in the mode number of the pump waves leads to a redistribution of energy concentrated in the side maxima of the point signal image and improvement in the quality of the wavefront reversal for a model with single-mode pump waves with equal mode numbers.

For the first time, the effect of temperature on the time response of a new modal filter (MF) based on a microstrip line with two side conductors grounded at both ends is estimated. The estimation was performed based on the results of quasi-static modeling, taking into account the temperature model and measuring the manufactured MF layout using the heat-cold chamber. The time responses to the ultrashort pulse at the MF output were analyzed. The results of modeling without taking into account losses, with taking into account losses, and measurements at temperatures of –50, 25, and +150°C are presented. Deviations of the delay and voltage amplitude are estimated. The consistency of the simulation and measurement results is shown. A small effect of temperature on the delay (about 1%) and a significant effect on the amplitude (up to 36%) of the first pulse were revealed. [ABSTRACT FROM AUTHOR]

The present study aimed to examine the validity of a novel method to assess cerebrovascular carbon dioxide (CO2) reactivity (CVR) that does not require a CO2 inhalation challenge, e.g., for use in patients with respiratory disease or the elderly, etc. In twenty-one healthy participants, CVR responses to orthostatic stress (50° head-up tilt, HUT) were assessed using two methods: (1) the traditional CO2 inhalation method, and (2) transfer function analysis (TFA) between middle cerebral artery blood velocity (MCA V) and predicted arterial partial pressure of CO2 (PaCO2) during spontaneous respiration. During HUT, MCA V steady-state (i.e., magnitude) and MCA V onset (i.e., time constant) responses to CO2 inhalation were decreased (p < 0.001) and increased (p = 0.001), respectively, indicative of attenuated CVR. In contrast, TFA gain in the very low-frequency range (VLF, 0.005–0.024 Hz) was unchanged, while the TFA phase in the VLF approached zero during HUT (−0.38 ± 0.59 vs. 0.31 ± 0.78 radians, supine vs. HUT; p = 0.003), indicative of a shorter time (i.e., improved) response of CVR. These findings indicate that CVR metrics determined by TFA without a CO2 inhalation do not track HUT-evoked reductions in CVR identified using CO2 inhalation, suggesting that enhanced cerebral blood flow response to a change in CO2 using CO2 inhalation is necessary to assess CVR adequately. [ABSTRACT FROM AUTHOR]

The paper presents the first results obtained with REVOC: 1, an automated auditory word recognition task used to assess receptive vocabulary in Spanish-speaking preschoolers. The task was programmed in Unity for 8' tablets in a self-application mode and included accuracy and response time as parameters. Non-probabilistic sampling was used. The sample consisted of 242 monolingual Chilean children between 4 and 6 years old. The list of vocabulary stimuli was extracted from TEVI-R, a paper-based test that assesses receptive (hearing) vocabulary. To estimate the automation's functionality and the parameters' values, the performance by age group at both global and item levels was evaluated. The results demonstrated a high level of performance in the selected items, with significant differences by age group in both accuracy and response time. The accuracy correlated negatively with total and correct latencies, with significant differences between age groups. The contrast by items allowed us to appreciate the time-precision relationship modulated by age, and the effect of word difficulty on latency. REVOC:1 adequately assessed receptive vocabulary and can advance to new stages of development. [ABSTRACT FROM AUTHOR]

We tested the impact of heart rate variability biofeedback (HRV-BF) on police performance in order to reduce protocol gaps and response time in scenarios that simulate life-threatening situations. The sample gathered fifty-one frontline police officers from the city of Barueri in Brazil who were distributed into two groups: (i) the experimental group (26 officers) which attended a 5-days protocol of HRV-BF training; and (ii) the control group (25 officers) which did not train. The performance of both groups was assessed before and after the HRV-BF training, and the results were compared. The findings show that HRV-BF positively impacted the experimental group's performance by decreasing procedural gaps and timing. In contrast, the performance of the control group remained stable. Based on this evidence, the Secretariat of Urban Security and Social Defense of Barueri decided to make HRV-BF into public policy. [ABSTRACT FROM AUTHOR]

A frequency-domain model is developed to analyze isolated interconnects of multilayer graphene-nanoribbon (MLGNR) and mixed carbon-nanotube bundle (MCB) driven by CMOS gates. The model derived is founded on an equivalent-single-conductor model of MLGNR and MCB that takes thermal considerations into account (i.e. TD-ESC). The model includes the derivation of transfer function of interconnect to estimate its delay and bandwidth performance. The attained results, reveals that among the neutral MLGNR (N-MLGNR), intercalation doped MLGNR (ID-MLGNR) intercalated with FeCl 3 , MCB and Cu interconnects, FeCl 3 ID-MLGNR achieves the best bandwidth efficiency. At a global interconnect length of 1 mm, FeCl 3 ID-MLGNR outperforms N-MLGNR, MCB, and Cu in terms of bandwidth with an improved bandwidth value of 12.2 GHz, 7 GHz, and 61.4 GHz, respectively. Further, employing the proposed CMOS-gate-driven model, for FeCl 3 ID-MLGNR, bandwidth is improved by nearly 7.52 × at global length (∼1 mm) in relation to the linear resistance model. Additionally, TD-ESC dependency of the proposed model reveals that FeCl 3 ID-MLGNR becomes more stable as interconnect resistance increases. • CMOS-driven interconnects of multilayer graphene-nanoribbon(MLGNR) and mixed CNT bundle(MCB) analysed in frequency-domain. • A temperature-dependent equivalent-single-conductor (TD-ESC) approach estimates interconnect performance accurately. • The derived transfer function for interconnects allows for the estimation of delay and bandwidth performance. • At global interconnect domain, FeCl3 intercalation-doped MLGNR (ID-MLGNR) outperforms neutral-MLGNR (N-MLGNR), MCB and Cu. [ABSTRACT FROM AUTHOR]

This work presents geometrically nonlinear transient analyses of various rotating blades. The structures are discretized through refined beams or multi-dimensional finite element models, which are generated using the Carrera Unified Formulation (CUF). The CUF offers a procedure to develop low- and high-fidelity one-dimensional, two-dimensional, and three-dimensional finite element models hierarchically and automatically. Various beam models were developed using different kinematics models based on Taylor or Lagrange expansion functions. Multi-dimensional models were obtained by merging beam and solid elements, exploiting the unique feature of Lagrange polynomials to have only pure displacements as unknowns. This property allows beam and solid elements to be coupled at the node level without requiring complicated mathematical formulations. By utilizing the Finite Element Method in conjunction with the CUF, the governing equations are written by including all rotation effects, namely the Coriolis term, spin-softening, and geometrical stiffening. In a total Lagrangian scenario, the Hilbert-Hughes-Taylor-α method and the iterative Newton-Raphson scheme are employed to solve the equations of motion. The proposed methodology has been applied to evaluate different blade configurations, comparing the solution obtained using linear, linearized, and nonlinear approaches. The results have been verified and validated by comparing them with existing solutions present in the literature. [ABSTRACT FROM AUTHOR]

Carbon Nanotube (CNT) is a material consisting of carbon atoms arranged in a series of condensed benzene rings that are coiled into a tubular structure. CNTs are used in various fields, such as reinforcing materials, coatings and films, biotechnology and biomedicine, and nano electromechanic systems (NEMS). The application of CNT in the biotechnology and biomedical fields as a nanopipe for carrying fluids is due to its high elastic modulus, good thermal and electrical conductivity, and other superior mechanical properties. One of the phenomena that can reduce CNT performance is flutter, so fluid-structure interaction is one of the important considerations in the design and application of CNTs. This study analyzes the effect of mass ratio on flutter instability due to flow in the CNT cantilever using the finite element method. Meanwhile, the system's responses are calculated using the Newmark method time scheme. The structural characteristics of the CNT were modeled as the EulerBernoulli beam. In this case, the fluid flowing in it is characterized in terms of two parameters, namely the average flow velocity (U) and the fluid mass density (per unit length). The results showed that the analysis of the response in the time domain is very sensitive to changes in flow velocity, the critical speed will decrease with an increase in the aspect ratio. and the mass ratio affects the flutter stability limit, where the larger the mass ratio for a given fluid density, the higher the flutter stability limit. The findings also revealed that the higher the density of the fluid flowing through the CNT, the lower its ultimate stability limit. [ABSTRACT FROM AUTHOR]

This paper presents a novel design technique of H-infinity based temperature and molar concentration controller for the highly non-linear system, namely continuous stirred tank reactor (CSTR). Model uncertainties and perturbation in CSTR parameters are considered in the proposed design. The stability, robustness, disturbance rejection capability, sensitivity to the parameter variations, and speed of the proposed controller are investigated through time and frequency response, complementary, and worst-case sensitivity analysis. Further, performances of the proposed controller are compared with the other existing controllers to reveal its effectiveness and accuracy. It is shown that, the proposed controller provides better time- and frequency-responses characteristics along with high disturbance rejection capability than the other existing controllers. The rise time, peak overshoot, and settling time of the proposed controller are found smallest among the conventional and AI based controllers and are 0.14 s, 0, and 0.6 s, respectively. Further, performance indices of the proposed controller are also found smaller than the other existing controllers. Also, the magnitude of sensitivity and complementary sensitivity functions is found in the desired limit under worst condition. Proposed control is found proficient to control the other parameter, such as molar concentration control, also. [ABSTRACT FROM AUTHOR]

The article presents the results of calculating time responses of a meander line (ML) turn to pulse excitation. The responses were calculated at the ML nodes analytically and numerically, and demonstrated coincidence. Besides, the created prototype of the ML turn was measured and showed good qualitative and acceptable quantitative agreement with the simulation results. Analytical models were found to be promising since they may significantly accelerate the design of such MLs in contrast to numerical methods which provide costly multivariate simulation of the time response during optimization. [ABSTRACT FROM AUTHOR]

Pressure-sensitive paint (PSP) is an optical sensor that can measure global pressure distribution by using the oxygen quenching of dye molecules. In particular, anodized aluminum pressure-sensitive paint (AA-PSP) exhibits a fast time response. AA-PSP has been used in unsteady measurements at supersonic and transonic speeds, such as on the surface of a transonic free-flying sphere or the wall of a shock tube when the shock wave passes. To capture such ultrafast phenomena, the frame rate of the camera must be sufficiently fast, and the exposure time must be sufficiently short. Therefore, it is desirable that the AA-PSP exhibits bright luminescence, high-pressure sensitivity, and fast response time. This study focused on pyrene-based AA-PSPs and investigated their characteristics, such as luminescence intensity and pressure sensitivity, at different anodization times, dipping solvents, and dipping concentrations. Furthermore, a time-response test using a shock tube was conducted on the brightest AA-PSP. Consequently, the time for a 90% rise in pressure was 2.2 μs. [ABSTRACT FROM AUTHOR]

This work presents a detailed, comprehensive study of a new structural design of protective devices with a circular cross-section (CS) (protective cables) for protecting equipment against ultra-wideband (UWB) pulses. Multiconductor structures with 2–5 conductors with and without a protective shield are considered. The disadvantages of using symmetric configurations of protective cables are shown. Their simulation, multivariate analysis, and optimization through heuristic search, as well as evolutionary strategies, were carried out. Optimization was carried out according to the amplitude (to minimize the maximum voltage level at the output of the structures) and time (to maximize the duration of the exciting signal) criteria. The optimization results allowed for increasing the duration and overall attenuation of the exciting UWB pulse. The article shows the possibility of improving the characteristics of such structures through their cascade connection, both among themselves and with strip protective structures. The results of parametric optimization of such structures are presented in the range of real (used in practice) geometric and electrophysical parameters in terms of amplitude and time criteria, as well as the matching criterion. The article also presents the developed prototypes of protective structures with a circular CS of three types: circular 3-conductor cable, flat 3-conductor cable, and circular 4-conductor cable. The experimental results describe how these prototypes were developed and created and confirm the feasibility of these protective structures to decompose the exciting pulse signal, which was previously shown only in simulation. Finally, it is shown that the use of asymmetry in the proposed cable structures can improve their protective characteristics. [ABSTRACT FROM AUTHOR]

The aim of almost any electromagnetic actuator development is to increase the electromagnetic force with which an actuator acts on a plunger with as fast a time response as possible while maintaining the dimensions as small as possible. This paper presents research on the impact of the lower core angle on the force and time response of a DC solenoid electromagnetic actuator. The research method is based on the analytical analysis of the magnetic path of the DC solenoid electromagnetic actuator and a comparison with the numerical simulation results. A transient numerical simulation was performed on a 2D axial-symmetric model of the electromagnetic actuator and included simultaneously solving time-dependent partial differential equations of the electromagnetic actuator’s magnetic, electrical, and mechanical subsystems. The magnetic subsystem was analyzed by the finite element method (FEM) using the ANSYS Electronics software package. The three prototype models with different lower core angles were produced and tested in the accredited Laboratory Center of KONČAR Electrical Engineering Institute. The obtained measurements are compared with the analytical results and numerical simulation results.

در این مقاله ، یک دیود تونل زنی تشدید با ساختار سد مضاعف AlAs / GaAs با استفاده از عملکرد سبز غیر تعادلی شبیه سازی شده است. یک لایه جذب InGaAs منطبق شده برای تشخیص نور در طول موج λ = 600 نانومتر به دستگاه اضافه می شود . میدان الکتریکی از طریق دستگاه و مشخصات نمودار باند انرژی ارائه شده است. جریان عکس دستگاه و منحنی های جریان جریان منبع در مقابل شدت نور مقایسه می شوند . در دمای اتاق ، بازده کوانتومی 95/0 برای دستگاه بدست آمد . پاسخ زمان گذرا دستگاه به دست آمد و وابستگی آن به پارامترهای ساختاری (ضخامت لایه جذب ، ضخامت کلکتور و انتشار دهنده ودوپینگ مخاطبین) ، شدت نور ، زاویه نور ساطع شده و سوگیری ولتاژ شبیه سازی شده و تأثیر آنها بر عملکرد دستگاه مورد تجزیه و تحلیل قرار گرفت. پهنای باند دستگاه به دست آمد. نتایج شبیه سازی نشان می دهد که وقتی بایاس ولتاژ افزایش یابد ، زمان افتادن کاهش می یابد و پاسخ دستگاه سریعتر است. با تغییر ضخامت لایه جذب و مخاطب ، پاسخ زمان RTD-PD تغییر می کند. تغییرات دوپینگ در لایه های تماس بر روی پهنای باند تأثیر می گذارد. نتیجه نشان می دهد که تغییرات شدت نور و زاویه نور ساطع شده ، پاسخ زمان گذرا را تغییر می دهند.

Micro-electro-mechanical-systems scale robots are prone to impulsive disturbances during operation. Such disturbance leads to adverse oscillations of the robot manipulator. So, it is essential to mitigate and control such unwanted oscillations. On the other hand, to capture size dependencies of such robot elements, it is required to adopt nonclassical models. To address these cases, robot manipulator is modeled as a mechanical rod, comprehensive rod models are utilized, proportional integral derivative (PID) controller is designed, and the time-domain response of the system is simulated in MATLAB. Results show that adopting proper gain values of the PID controller leads to total rejection of the pulsive disturbances. However, findings conceal the importance of the nonclassical rod model such that strain gradient (SG) model shows less oscillatory amplitude than the classical theory (CT) model. While considering the nonlocal model effects (NL), such undesired vibrations are bigger than CT model. In other words, meanwhile, a simple PID controller can reject the disturbance for SG models; a stronger controller should be adopted to reject such pulsive disturbances with NL models. Eventually, it is valuable to note that to suppress unwanted oscillations in small-sized robots, PID closed-loop feedback controller is a decent choice because of the simplicity and less costs. Application of successful control design alongside the proper nonclassical theory leads to neutralizing the disturbances and increases the robot manipulator precision. [ABSTRACT FROM AUTHOR]

Residuální kmitání způsobené poddajnostmi v soustavě lineárního pohonu a zátěže ovlivňuje přesnost výsledné polohy pracovního členu. Článek se zabývá modelováním dynamického chování zátěže tvořené seismickou hmotou uloženou na dvou plochých pružinách. Uvedeny jsou dva lineární modely – spojitý model odvozený na základě teorie ohybových kmitů prizmatického nosníku s odpovídajícími okrajovými podmínkami a diskrétní model se soustředěnými prvky o jednom stupni volnosti. Oba modely byly použity k simulaci pohybu připojené soustavy pro různé průběhy zdvihových funkcí motoru a porovnány s průběhy naměřenými na reálné soustavě.

This paper deals with the evaluations of lower and upper bounds of dynamic responses and natural frequencies for structures with uncertain interval parameters. The structural physical parameters, geometric dimensions and initial conditions can be considered as interval parameters. The modified Chebyshev interval method (MCIM) is presented to handle the uncertainties. In comparison with the Chebyshev interval method (CIM), MICM provides with tighter bounds of the time responses and natural frequencies without a significant increase in computation time. Monte Carlo method is also used to provide with exact bounds. MICM, CIM and Monte Carlo method are applied for structures with interval parameters, and the efficiency and accuracy of CIM and MCIM are verified.

Target flowmeter is commonly used for measuring flow rates, but there are some shortcomings of the conventional target flowmeter, such as complex structure, low sensitivity, non-linearity. Here, a Surface Acoustic Wave (SAW) sensor-based target flowmeter has been proposed where a SAW sensor is placed on the target rod of the flowmeter. When liquid flows through the pipe in contact with the target rod, the force is produced. This force then acts on the target rod and deflects the target rod from its original position, which results strain in it. SAW sensor senses the strain level at different flow rates, and the output is in terms of delayed time response of the order of a nanosecond. The output is non-linear with respect to the flow rate and it is linearized with the help of a neural network technique. This minimizes the non-linearity error up to 0.27% of full-scale output (FSO). The modification in the target type flowmeter is done with the help of the SAW sensor in such a way that the flow transmitter can transmit sensed information through the wireless channel. Simulation and mathematical approaches are reported in this paper for the range of 0 to 1200 LPH. [ABSTRACT FROM AUTHOR]

Using multi transmission line (MTL) model, a compact circuit model for mixed multiwall carbon nanotube (MMWCNT) interconnects is proposed. Using the proposed circuit model, an algorithmic model is proposed for calculating the transfer matrix of these interconnects. In the proposed circuit model and also algorithmic model, capacitive, inductive and tunneling effects between the carbon layers is considered. Moreover the concept of distributed circuit block parameters is proposed for this type of interconnects. This model is compact because it can be used in wide range and technology of interconnects. Also using this model, any change in the physical parameters of the nanotubes can be considered in the circuit model and algorithmic model. Using the circuit model and algorithmic model one can calculate various stability and time domain responses for MMWCNT interconnects in VLSI circuits. In this paper after proposing the circuit model and algorithmic model, we have calculated step time response and Nyquist response of MMWCNT interconnects. The results show that by increasing the length and diameter of the tubes, the delay of the interconnects is increased and its stability is increased too.

Pressure-sensitive paint (PSP) is an optical sensor that can measure global pressure distribution by using the oxygen quenching of dye molecules. In particular, anodized aluminum pressure-sensitive paint (AA-PSP) exhibits a fast time response. AA-PSP has been used in unsteady measurements at supersonic and transonic speeds, such as on the surface of a transonic free-flying sphere or the wall of a shock tube when the shock wave passes. To capture such ultrafast phenomena, the frame rate of the camera must be sufficiently fast, and the exposure time must be sufficiently short. Therefore, it is desirable that the AA-PSP exhibits bright luminescence, high-pressure sensitivity, and fast response time. This study focused on pyrene-based AA-PSPs and investigated their characteristics, such as luminescence intensity and pressure sensitivity, at different anodization times, dipping solvents, and dipping concentrations. Furthermore, a time-response test using a shock tube was conducted on the brightest AA-PSP. Consequently, the time for a 90% rise in pressure was 2.2 μs.

Principal Component Analysis is used for damage detection in structures excited by harmonic forces. Time responses are directly analysed by Singular Value Decomposition to deduct two dominant Proper Orthogonal Values corresponding to two Proper Orthogonal Modes. Damage index is defined by the concept of subspace angle that a subspace is built from the two Proper Orthogonal Modes. A subspace angle reflects the coherence between two different structural health states. An example is given through the application on a part of a real prestressed concrete bridge in Luxembourg where different damage states were created by cutting a number of prestressed tendons in four scenarios with increasing levels. Results are better by using excitation frequency close to an eigenfrequency of the structure. The technique is convenient for practical application in operational bridge structures.

The aim of almost any electromagnetic actuator development is to increase the electromagnetic force with which an actuator acts on a plunger with as fast a time response as possible while maintaining the dimensions as small as possible. This paper presents research on the impact of the lower core angle on the force and time response of a DC solenoid electromagnetic actuator. The research method is based on the analytical analysis of the magnetic path of the DC solenoid electromagnetic actuator and a comparison with the numerical simulation results. A transient numerical simulation was performed on a 2D axial-symmetric model of the electromagnetic actuator and included simultaneously solving time-dependent partial differential equations of the electromagnetic actuator's magnetic, electrical, and mechanical subsystems. The magnetic subsystem was analyzed by the finite element method (FEM) using the ANSYS Electronics software package. The three prototype models with different lower core angles were produced and tested in the accredited Laboratory Center of KONČAR Electrical Engineering Institute. The obtained measurements are compared with the analytical results and numerical simulation results. [ABSTRACT FROM AUTHOR]

Generally, in control gain tuning, settling time and overshoot are altered to be smaller through time-consuming and labor-intensive experiments. Such experiments can be automatically performed in the computer in a short time if the time response can be predicted. Kaneko et al. proposed a new approach for predicting the response of a closed-loop system using one-shot experimental data, but this approach takes into consideration the structure of the closed-loop transfer function. Thus, two methods have been proposed that do not require the structure of the transfer function. One method is based on the finite impulse response estimated from one-shot experimental data by Matsui et al., but the design guideline for an unstable system is not shown. The other method is Virtual Time-response based Iterative Gain Evaluation and Redesign (V-Tiger), which is based on the frequency components of one-shot experimental data by Kosaka et al. However, this proposed V-Tiger has the following issues: 1) Inability to predict disturbance response and input disturbance response. 2) The initial value used for optimization must be a controller that stabilizes the system. Hence, in this paper, we describe the countermeasures against these issues.

BackgroundInternational basic nuclear physics research and fusion energy research need pulse radiation detection system with higher and higher accuracy. A pulse scintillator radiation detection system with large dynamic range is a key method to obtain detailed information such as the time and amplitude of small signals in a strong interference environment, so as to analyze and study the characteristics of these pulse radiation fields.PurposeIn order to meet the needs of covering design and optimization of the scintillator pulsed radiation detection system, a new express analysis method is proposed, which covers a large-scale dynamic range of time response characteristics.MethodsThis new express analytical unit mainly contains a gated photomultiplier tube (PMT), a gated high voltage (HV) and an oscilloscope. Firstly, a picosecond pulsed laser has been used to test the intrinsic property of this method. Finally, the time response characteristic of low-afterglow liquid scintillator has been studied by this method on a pulse X-ray machine. According to the experimental data, a decay curve of the liquid scintillator has been processing with double exponential fitting.ResultsThe decay curve of this liquid scintillator has been measured with a range of four scales.ConclusionsThis method has a vertical scope covering five scales.

BackgroundThe prompt fission neutron spectrum (PFNS) is an important nuclear reaction data. Coincident measurement between neutron detectors and parallel plate avalanche counters (PPAC) is widely used to measure the PFNS below the energy of the neutron source, hence most of the non-fission neutrons can be exclude.PurposeThis study aims to develop a PPAC to satisfy the PFNS measurement and performance test.MethodsFirst of all, a ten-cell PPAC was designed with low-pressure flow working gas and individual cell functionality. Then the software named "Garfield" was used to simulate the distributions of electric field of two kind of fission chambers, i.e., wire-electrode chamber and plate-electrode chamber, under the same geometric dimensions and working conditions. Finally, the structure and the performance of the PPAC were introduced in detail, and relevant performance of this PPAC was tested by experiment.ResultsThe full width at half maximum (FWHM) of the time-correlated spectrum between two neighbor cells using a 241Am α source is 620 ps. The FWHM of the time-correlated spectrum between a PPAC cell and a liquid scintillator detector is 880 ps using a 252Cf fission source.ConclusionsThe experiment confirms that the time resolution of the designed PPAC is good enough for high event rate measurements.

Breakdown of stackers and excavators in opencast mines is possible because of operating, manufacturing and structural causes, and it produces high financial losses. These can be prevented by using various measures, including analyses and strength tests, with computerized modeling and simulation using FEA or other techniques being implemented in the recent years. In this paper a fatigue study is conducted on the boom of a BWE. Based on a computer model of the boom previously developed in SOLIDWORKS by our author team, first the modal analysis is conducted for three positions of the boom by studying the frequency response during the excavation process. This is followed by the time response determination corresponding to the maximum displacement frequency, in order to assess the stress during the excavation process, which causes the material fatigue in the boom structure. It was found that the maximum displacements appear when the BWE boom operates in a horizontal position. The aim was to estimate the period of time to failure in order to prevent unwanted accidents, and to develop a method that is applicable to any surface mining or industrial machine with similar structure.

An investigation into the dynamic response and frequency split behavior of a cylindrical fused silica resonator is performed via simulations and experiments. For this purpose, a structure for the cylindrical resonators with appropriate dimensions has been designed and fabricated. A laser Doppler vibrometer is utilized for the experimental quantification of the physical characteristics of the resonator. Natural frequencies of n = 2 modes, frequency split and quality factor have been extracted from the measured frequency sweep. Then the influence of mass change on the frequency split is investigated by chemical trimming. Time response predictions utilizing a ring model is employed to predict the resonant amplitudes as well as the influence of driving force and input angular velocity variations. The numerical predictions of the relationship between the mass mismatch and the frequency split are found to be consistent with the exper imental results. Predictions of frequency split of resonators via the simulation model are envisaged to greatly increase the efficacy of the chemical trimming process. [ABSTRACT FROM AUTHOR]

Fig. Response of perovskite thin films electrical conductivity to light variation. (a) In function of time (b) in function of light intensity • Time response of the electrical resistivity of perovskite thin films at light exposure. • Temperature dependencies of the electrical resistivity of CH 3 NH 3 PbI 3. • Analysis of optical properties and band gap model. Structural and morphological properties of CH 3 NH 3 PbI 3 thin films deposited by spin coating, with different spin speeds on glass and ITO patterned substrates were investigated. It results that long length acicular crystals, growth parallel to substrates (>200 μm for spin speeds of 800RPM/min). For low deposition spin speed these crystals are interconnected and deposited films present a high electrical conductivity. The XRD investigations indicate the formation generally of the cubic phase, or a mixture between cubic and tetragonal phase. For compact films the absorption is high over a large range of spectral domain (from 200 nm to 2100 nm), the transmission being lower than 20% in IR and less than 15% in the visible domain. From electrical properties point of view, films are highly sensitive to light. An increase of the electrical conductivity with three order of magnitude is noticed when films are exposed to a white light of a solar simulator with an intensity of 1000 W/m2, but also an important increase is observed when films are exposed to a continuous low intensity ambient light, at least one order of magnitude in less than six seconds. This behavior is identical no matter the films thickness. The variation of the electrical conductivity at exposure to light in function of time and light intensity and the variation of the electrical conductivity in function of temperature were investigated and interpreted. The experimental results, since now, comforting the assumption of a multiband model. [ABSTRACT FROM AUTHOR]

An emergency can be interpreted as a condition that is judged as a person's dependence on receiving medical action or immediate evaluation of the surgical action. Response time is the speed and the accuracy of service that is required by the patients to get appropriate treatment with their about diseases since entering the door of the IGD. Good response time for the patients is about 5 minutes, if it is more than it, it can make patient life’s in danger even can cause death. The aim of this study was to determine the correlation between emergency situation to response time in coronary heart disease patients at emergency room Siti Khadijah Islamic Hospital Palembang. The design of this study used an analytic observational method and cross-sectional approach, subjects of this study was the nurses of emergency room Siti Khadijah Islamic Hospital Palembang, as much as 30 respondents. The study was conducted from June 17th - July 7th, 2017. The data study was recorded on the observation sheet. Then this study data were analyzed by using chi-square test. Based on the result of data analysis by chi-square test showed that there was a significant relationship between emergency situation and response time on coronary heart disease patients and the ρ-value was 0.003

Utilizing ball-type auto-balancer in rotating systems is a popular method in industry in order to eliminate the rotational vibration. Recently, by using numerical methods, it is shown that a ball-type auto-balancer equipped with both the radial and peripheral springs, ball-spring automatic balancer (AB), is an improved model. In this paper, due to the advantages of analytical methods over the numerical ones, the complete system dynamics, i.e., the stability analysis and the time response, of the rotor equipped with ball-spring AB is analyzed by the multiple scales method as a unified technique. Therefore, with no need for implementing any other stability theories, the stability analysis is a definite advantage of this method due to the less computation cost. Moreover, the time responses show a good agreement with those obtained through the numerical method. Finally, for the first time, the influence of the peripheral springs on the time responses and the stable equilibrium points of the rotor with ball-spring AB is studied in details. The results show that the peripheral springs decrease the vibration amplitude at the transient and leave some residual imbalance at the steady state and accordingly, there is a compromise between the system working performance at the transient and the steady state. [ABSTRACT FROM AUTHOR]

A key problem in prediction theory is to improve adaptiveness to data characteristics. This paper proposed a novel method called buffered adaptive grey rolling model or BARGM model, which combines the buffer operator and grey rolling model. First, the new model decomposes original sequence into continuous data slices, and uses feedback input to adjust modeling data by buffer operator with variable weight on each data slice, then a extended grey forecasting model is utilized to model the adjusted data slices stepwisely and generate the extrapolation values. With comparison to GM(1. 1). BARGM lias two obvious features: Changing the monotonicity of traditional time response function and strong expansibility. The case study uses the BARGM and benchmark models to analyze China's greenhouse gas emission data, and the results demonstrate that the accuracy of fitting and prediction improve obviously, and prove the new model's effectiveness. [ABSTRACT FROM AUTHOR]

To acquire the direct time response of ZnO crystals to high energy particles, a dual-channels single photon correlation (DCSPC) system based on the measurement of the autocorrelation function of the fluoresce temporal profile was employed. The measuring resolution of the DCSPC system calibrated by Cerenkov luminescence is 46 ps. With this DCSPC system, the fast decay time constants of ZnO:Ga, ZnO:In and ZnO:Sc under charged particle alpha and beta excitation were successfully measured, which are 1.56 ns, 0.48 ns, 0.12 ns, and 1.11 ns, 0.40 ns, 0.10 ns, respectively. For all the three samples, it is found that the decay time constants under beta excitation are faster than those under alpha excitation, indicating that ZnO crystal is a fast scintillation material with pulse shape discrimination (PSD) ability. This would be applied in selective detection of mixed radiation field, particularly where high counting rate is required. [ABSTRACT FROM AUTHOR]