Readout for simple and precise analog acoustic impact initialization

An economic concept of acoustic shock wave sensing readout system for simple computer processing is introduced in this work. Its application can be found in precise initialization of the stopwatch from the starter sound, handclap or gun in competitive sport races but also in many other places. The proposed device consists of several low-cost commercially available components and it is powered by a 9 V battery. The proposed device reliably reacts on incoming acoustic shock wave by generation of explicit impulse having controllable duration. It significantly overcomes basic implementations using only a microphone and amplifier (generating parasitic burst instead of defined and distinct impulse) or systems allowing a limited number of adjustable features (gain and/or threshold of the comparator—our concept offers the adjustment of gain, cut-off frequency, threshold level and time duration of active state). In comparison with standard methods, the proposed approach simplifies and makes sensing device less expensive and universal for any powder-based starting gun (without necessity to adapt starting gun). The proposed device, among others, has the following features: impulse duration can be controlled from hundreds of μs up to 2.3 s, the gain range of linear part of processing from 6 to 40 dB and open-collector output compatible with 5 V TTL or 3.3 V CMOS logic. The initialization has been tested in the range from tens of centimeters up to four meters. In order to highlight the important spectral components, the spectral character of the signal can be optimally reduced by a low-pass filter. The quiescent power consumption of the designed simple analog circuit reaches 90 mW. Several use cases, response of the designed system on gunshot signature, talking, hand-clapping and hit on the sensing microphone, are studied and compared to each other. Simulation and experimental results confirm functionality of the realized system.

Evaluation of an Experimental Modal Analysis Device for Micromilling Tools

Stable machining conditions in the micromilling process are critical to increase the production of small components. Precise frequency response measurements are essential to generate the stability diagrams. Therefore, impact hammer application which mostly relies on operator's skill and experience is very time-consuming and can produce imprecise results. This study aims to analyze a device developed to perform the experimental modal analysis of micromilling tools. The device facilitates the positioning of a fixed point Laser Doppler Vibrometer ( LDV ) as well as providing automatic and reproductive impact tests. Two mirrors supported by kinematic mounts are used to position the laser beam on the micro milling tool surface. The impact hammer is composed of a force sensor attached to a custom designed flexure-based body, in which an automated electromagnetic releases the mechanism. A set of experiments were conducted to perform the precision positioning of the laser beam and the impact hits. The impact force repeatability in terms of the magnitude and impulse duration were also investigated. The application of the device was demonstrated through modal testing of two micromilling tools with two different diameters.

Surface Interactions of Transonic Shock Waves with Graphene-Like Nanoribbons

Graphene-like nanoribbons (GLNRs) were fabricated (length—20 μm; width—2 μm) and subjected to blast-like pulsed pressure >1.5 GPa (pulse speed ≈1 Mach, impulse duration, ≈µs) to examine the amount of absorption. GLNRs prepared by the chemical vapor deposition technique via controlled biomass combustion were subjected to investigate the structure–property characteristics using microspectroscopic techniques. Following this, GLNRs were employed to high strain rate (HSR) studies with the help of the technique known as split Hopkinson pressure bar (SHPB) to evaluate numerous dynamic parameters. The parameters were extracted from variations in the stress and strain rates. Their analysis provided insight into the damping response of blast energy within GLNRs. By and large, the impact generated modified the microstructure, exhibiting modifications in the number of layers, conjugated loops, and dynamic disorder. Signal processing analysis carried out for incident and transmitted impulse pressure revealed an interaction mechanism of shock wave with GLNR. Details are presented.

INFLUENCE OF AIR TEMPERATURE ON DURATION OF IMPULSE OPENING SPRAY IN THE ENGINE INTAKE MANIFOLD WHILE CAR OPERATION IN VARIOUS CONDITIONS

Introduction. The air temperature in the intake manifold is used by an electronic engine control unit to adjust the injection time of the fuel injector top. The intake air temperature is variable and depends on the operating conditions of the vehicle. When air intake temperature decreases, the duration of the nozzle opening pulse increases and, conversely, as air intake temperature increases, the duration of thenozzle opening pulse decreases.Materials and methods. The paper demonstrates the analysis of the air temperature effect in the intake manifold of the engine on the duration of the injector opening pulse while the engine is idling and when the vehicle is moving with different speed conditions on the flat, mountainous and alpine sections of the road.Results. As a result, the research showes that the movement of the car at high speeds on the flat sections of the road leads to a significant decrease of air temperature in the intake manifold and an increase in the duration of the injector opening pulse. Moreover, when the vehicle moves on the mountainous sections of the road, the effect of air temperature in the intake manifold on the nozzle opening impulse duration is insignificant, since the speed of the vehicle movement is influenced by the complexity of the terrain and the parameters of the mountain and high-mountain roads.

Effect of changing of the parameters of the cable network of monitoring systems of high-rise buildings on the basis of string converters on their operability

The article is devoted to the problem of improving the reliability of monitoring systems for the technical conditions of high-rise buildings. The improvement is based on string sensors with an impulsed excitation method ensuring the maximum signal-to-noise ratio at their output. The influence of the parameters of the monitoring system on the shape of the excitation impulses of the string, and, consequently, on the amplitude of the string vibration of the string converter is also considered in the article. It has been experimentally proved that the parameters of the excitation impulses of the string converters. The article presents the results of the experiments showing the effect of the fronts duration of the excitation impulses on the amplitude of the oscillations of the strings. The influence of the fronts duration of the excitation impulse with the frontal lengths up to 0.5 ms is studied at the excitation impulse duration not exceeding 0.5 times the duration of natural oscillation periods of the string. The experimental data are compared with the theoretical ones and hypotheses explaining their difference are advanced. The article suggests some methods of reducing the influence of the cable-switching equipment system parameters on the amplitude of string oscillations. The possibilities of improving the reliability of the systems developed on the basis of string sensors with an impulsed excitation method and used for monitoring the technical conditions of the high-rise buildings are proposed.

Improvement of Harvesters for Tires by Means of Multi-Physics Simulation

The specific working conditions of piezoelectric harvesters for scooter tires are analyzed. Calculated and experimental results show that the excitation of the harvester can be considered a series of separated impulses. Harvester response to an ideal impulse is analyzed with a single-mode model. An optimal ratio between impulse duration and natural period of the harvester that maximizes harvester excitation is found. A numerical finite element (FE) model of a bimorph cantilever harvester is developed in COMSOL and validated by means of experimental tests. The validated FE model is used for showing that an actual harvester excited by road impulses generates a large voltage only if there is a specific relation between impulse duration and natural period of the harvester. Starting from the validated FE model, small harvesters suited to tires are developed and analyzed. Also these harvesters show the best performance for a specific range of impulse durations, which corresponds to the highest speeds of the speed range of the scooter (50–80 km/h) and to high levels of acceleration.

Urinary incontinence: Clinical observation on 30 patients undergoing treatment with F.R.E.M.S (Frequency Rhythmic Electrical Modulation System)

Aim of the study: Urge incontinence is considered to be a dysfunctional pathology of social interest due to the psychological and relational implications of such disability, the elevated number of affected patients and the consequent treatment costs. We propose an innovative non-pharmacological and non-invasive care methodology: Frequency rhythmic electrical modulation system (F.R.E.M.S.) therapy (FT), based on the administration of electric fields of monophasic pulsed, negative, asymmetric current, generated by a neurostimulator with the characteristics of low variable frequency, high voltage and very low impulse duration. Material and Methods: 30 patients were studied with urodynamic evaluation and radiological diagnostic techniques, and underwent 2 cycles of 15 days therapy, with a 12 months follow-up. Results: In 93% of cases, we obtained a positive result, with either disappearance or improvement of symptoms. Conclusion: Although the Authors believe that clinical results deserve further neurohistological and immunohistochemical studies, in order to define the anathomophysiological and biochemical changes induced by FT, they propose it as a possible alternative to traditional pharmacological therapy and electrical stimulation.

Peculiarities of Non-Stationary Temperature Distribution of Optical Non-Transparent Anisotropic Thermoelement at Impulse Ray Excitement

The solutions of the non-stationary equation of thermoconductivity for the optical non-transparent thermoelement at impulse ray excitement are presented in the paper for two-time ranges: when the ray current falls (0<t<tau) and when it stops (t<tau). It is shown that the behavior of temperature distributions essentially depends on the relationship between the impulse duration (tau) and relaxation time (tau0) of temperature shifts over the whole volume of anisotropic thermoelement, arising at the impulse ray excitement. The non-stationary temperature distributions are studied for the long, short and middle impulse excitement.

Dual Mechanical Environment Simulations on Liquid Reserve Batteries

Dual mechanical environment simulators are usually used to supply recoil force and centrifugal force for simulation of liquid reserve batteries during artillery projection. When the vehicle with fuze batteries impacts the wooden block rotating with high speed, whether the transient impact parameters and the time required for the vehicle reaching the rated revolution are in accordance with the test conditions of fuze batteries is one of the key technologies. Finite element simulations are implemented for the transient vehicle impact process, the variation of vehicle acceleration under different projection velocities, the variations of vehicle acceleration and impulse duration with different wooden block thicknesses, and the time required to achieve stable rotational speed are discussed in this paper, which can be a reference for the simulator design.