Ground Vibrational Level Research Articles

Feedback from acoustic and vibration mitigation measures on buildings along railways

Designing buildings very close to existing railway track with heavy commuting traffic requires special attention regarding noise and vibration. The situation reported in this paper is that of an existing embanked railway line 20 km East of Paris, where buildings have been constructed right above the embankment and not too far from a station. Consequently, as the tracks cannot be modified, the mitigation measures have been taken on the receiver side, i.e. the buildings. The noise and vibration mitigation measures implemented in buildings in order to limit occupant annoyance are first described. Then, acoustic and vibration measurements inside and outside of the considered buildings are discussed and results examined with respect to the implemented mitigation solutions. Finally, measured vibration and sound levels are compared to target values under discussion for new regulation on ground borne-noise and vibration levels in buildings along railways.

Monitoring of ground and building vibrations caused by train wheel defects

This paper describes a study performed on train wheel defects and their effect on rail vibrations. The paper describes a test setup allowing the researchers to capture ground vibrations at the desired level of detail to prove to what extend wheel quality influences ground vibration levels and associated nuisance to people. The analysis of the measurement signals shows that the individual axles of a passing train can be detected excellently with the signal from the axle detection and the vibration sensors. The signals from various sensors in the measurement setup are synchronized with high time accuracy, making it possible to overlay the time interval of an axis passage over the signal from the vibration measurements. This makes it possible to track vibrations at bogie and axle level. The distance of measurement points from the track is ultimately the determining factor for the extent to which vibrations are dominated by an axle, a bogie, a wagon or the entire train. In addition, direct wheel roundness measurements have been performed for trains that appear to have defect wheels based on ground vibration data. With the track based measurements, the ground vibration measurements and the direct wheel measurements an unique data set has been generated, allowing for an evaluation of the importance of defect train wheel from the perspective of vibrations nuisance to the environment. Relations of measured vibrations to other parameters, both rolling stock related and environmental parameters were investigated based on the generated set of data. The analysis on the data reveals interesting relations between train wheel parameters and ground vibrations, which are discussed in this paper.

Experimental investigation of dynamic features and propagation law of ground vibrations induced by a suspended monorail train

This study focuses on experimental investigation of the dynamic features and propagation law of ground vibrations induced by suspended monorail transportation (SMT), which is rarely reported. First, a comprehensive field measurement of suspended monorail train-induced ground vibrations is performed and the acceleration responses at different measurement positions are obtained. Then, the vertical and lateral vibrational responses are elaborately analysed in the time and frequency domains. The dynamic features and transmission laws of the ground vibrations are revealed, and some interesting phenomena are discovered. Finally, an effective signal post-processing method is adopted to furthest reduce signal truncation errors. The 1/3 octave analysis method is adopted for elaborately evaluating both the ground vibration levels with time and frequency division under different train operating conditions. The research results can provide useful guidance for route selection of SMT and numerical model validation.

Analysis on characteristics of ground vibration induced by underground high-speed trains based on in-situ test

With the increasingly emerging traffic intersection form of high-speed railways passing underneath integrated transport terminals, the ground vibration induced by trains running on underground high-speed railways has attracted extensive attention. In combination with the engineering example of a high-speed railway in construction passing underneath an airport, the wheel-drop impact test in the high-speed railway tunnel was designed to obtain the vibration characteristics of surrounding soil. The vehicle-track-tunnel-ground semi-analytical three-dimensional model was established to determine the initial dynamic load condition of the vehicle loads. The amplitude-frequency characteristic and transmission law of the ground vibration induced by trains running on underground high-speed railways were predicted and analyzed. The influences of different operation conditions, track parameters, and tunnel burial depths were compared. The research results show that the ground vibration obtained through the wheel-drop test is greatly attenuated within 10 m from the track centerline, with an attenuation rate up to 70%. The vertical vibration amplitude is obviously larger than that of the other two directions. The lateral ground vibration amplitude is the smallest with the slowest vibration attenuation speed. When the high-speed train passes through at the speed of 350 km/h, the vertical and lateral vibration levels of the ground surface within 80 m range are 20∼80 dB and 43∼72 dB, respectively. The maximum attenuation coefficient of Z-vibration level reaches 0.276 dB/m. For each increase of 50 km/h of the train speed, the Z-vibration level of the ground increases by about 2 dB. The smaller fastener stiffness leads to the greater ground vibration within 20∼50 Hz. The ground vibration level is positively correlated with the fastener stiffness above 79 Hz. When the burial depth of the tunnel is greater than 14 m, the burial depth of the tunnel has little effect on the change of the Z-vibration level of the ground.

Study on blast-induced vibration of single-hole cylindrical charge

It is essential to study the blast-induced vibration of cylindrical charge so as to reduce ground vibration level and protect the surrounding environment. In this paper, the Heelan model is used to study the generation and propagation mechanisms of blasting vibration induced by single-hole cylindrical charge. It shows that the superposition of vibration waves induced by explosives in different positions of the cylindrical charge causes the increase of peak particle velocity ( PPV) in the region along the propagation direction of detonation waves. The vector peak particle velocity ( VPPV) versus distance for different stemming lengths ( SL) indicates that the linear attenuation between the VPPV and the exponential of distance appears only over a certain distance. Hence, the traditional formula for PPV prediction is suitable just in the middle and far field, not in the near field. The influences of charge length, detonation velocity and initiation pattern on the blast vibration are also investigated. The generation of Mach waves is determined by the relationship of scale between velocity of detonation ( VoD), P-wave velocity, and S-wave velocity. Over a certain value, the charge length doesn’t affect maximum VPPV, but affects the range of VPPV with relatively large values. Moreover, the bottom and top detonator positions have similar consequences on vibration control in the far field as the influence of limited charge length on blast vibration can be ignored. The VPPV of the middle initiating is almost twice as much as the other two detonator positions in the far field. Thus, in practical blasting, the middle initiating needs to be avoided.

Dynamics and energetics of the K([formula omitted]) + H[formula omitted] ([formula omitted]) reaction: Significance of orientational and (ro)vibrational contribution

The significance of orientational and (ro)vibrational excitations on the K(2S) + H2 (X1Σg+) reaction dynamics is presented here by performing the exact time-dependent wavepacket calculations using the Coriolis coupling (CC) approach. Employing the new accurate ab initio ground electronic surface 1 2A′ reported by Yuan et al. (2018), the dynamical quantities such as integral cross sections and thermal rate constants are computed within the CC and CS (centrifugal sudden) methods. All partial wave contributions of J (total angular momentum) up to 90 are required to get the convergence in dynamical results up to the collision energy of 3.5 eV. The present study attests that the ground and first vibrational level dynamics is insignificant. For v=2, the reaction probability is monotonically increasing, followed by the onset noted near 1.25 eV, as a function of collision energy up to 3.5 eV. Further, the kinematic effects (replacing H by D atom) on the title system is also performed and found that the KH product formation is more favored than the KD product via HD depletion path.

High-resolution photoelectron spectroscopy of the very weakly bound MgNe molecule

ABSTRACT We report on the characterisation of the X + 2 Σ + ground electronic state of MgNe + by photoionisation, mass-analysed threshold-ionisation (MATI) and pulsed-field-ionisation zero-kinetic-energy photoelectron (PFI-ZEKE-PE) spectroscopy and the observation of the metastable a 3 Π 0 state of MgNe. Rotationally cold MgNe was generated in a laser-ablation supersonic-beam source in both the X 1 Σ + ( v ″ = 0 ) ground state and a 3 Π 0 ( v ″ = 0 ) metastable electronic state. PFI-ZEKE-PE spectra with full resolution of the vibrational structure and partial resolution of the rotational structure were recorded from the X 1 Σ + ground state following resonant ( 1 + 1 ′ ) two-photon excitation via selected rovibrational levels of the C 1 Π intermediate state and from the a 3 Π 0 metastable state following single-photon excitation. The lowest six vibrational levels of the X + 2 Σ + state were observed, covering 80% of the X + 2 Σ + potential-well depth. The experimental data were used to determine potential-energy functions, dissociation energies, and molecular constants for the X 1 Σ + , a 3 Π 0 and C 1 Π states of MgNe and the X + 2 Σ + state of MgNe + . With dissociation energies D 0 of 12(3) cm−1 and 10(3) cm−1, respectively, the X 1 Σ + and a 3 Π 0 states of 24 Mg 20 Ne are extremely weakly bound. In contrast, the X + 2 Σ + state of 24 Mg 20 Ne + has a dissociation energy D 0 of 185(3) cm − 1 and 12 bound vibrational levels. From the difference between the adiabatic ionisation energies of the X 1 Σ + (61 498.5(4) cm − 1 ) and the a 3 Π 0 (39 645.1(3) cm − 1 ) states, the term value of the a 3 Π 0 ground vibrational level is determined to be 21 853.4(5) cm − 1 . These results are compared with those of earlier experimental studies and ab initio quantum-chemical calculations.

Spectroscopic modeling and measurements of the CN Violet and Red systems for the development of nonequilibrium temperature and speciation diagnostics

The uniquely strong radiative properties of the cyano-radical (CN) make it an important species to model in high-enthalpy, nonequilibrium flows containing carbon and nitrogen. In this work, spectroscopic models for the Violet and Red systems of CN have been developed and validated at wavelengths in both the ultraviolet (UV) and near-infrared (NIR) regimes that would provide quantitative CN rovibrational temperature and concentration. The ultraviolet wavelengths chosen probe high-lying (J′′=30.5−40.5) and low-lying (J′′=0.5−5.5) rotational states in the ground vibrational level (v′′=0) of CN along with high-lying rotational states in the third excited vibrational level (v′′=3) of CN. Meanwhile, the NIR wavelengths cover a range of lower rovibrational content, including high-lying and low-lying rotational levels from the ground up to the fourth excited vibrational level of CN. Dilute cyanogen (C2N2) in argon (Ar) mixtures were shock heated to produce stable quantities of CN that could be spectroscopically studied. In the UV, fixed-temperature absorption cross-section measurements at different wavelengths and a fixed-wavelength temperature sweep for the chosen diagnostic wavelengths enabled an evaluation of the different spectroscopic models and their ability to correctly infer the post-shock temperature in mixtures with high Ar dilution. In the NIR, the lasers were scanned at 100 kHz to probe multiple transitions over different rovibrational states over a wide range of temperatures, and both Einstein A’s and relative line positions of observed Red transitions of CN were experimentally quantified.

Studi Studi Pengaruh Tingkat Getaran Tanah (Ground Vibration) Akibat Peledakan Terhadap Bangunan sekitar Pit 13 HW

PT. PAMA is a company engaged in mining and is a contractor of PT. Indominco Mandiri which has been running since 1996. The work contract given is blasting, from blasting activities many impacts arise, one of which is ground vibration, therefore it is necessary to measure the level of ground vibration in the west block area where there are several critical areas in the form of buildings such as offices , solar (fuel oil) storage, and PT. Indominco Mandiri, where there have been complaints regarding large vibrations and the potential for diesel spills from fuel oil. In the study the peak vector sum (pvs) value produced in December 2022 was 1.57 mm/s with the closest distance of 785 meters and in January 2023 4.21 mm/s with a distance of 500 meters. The maximum use of explosives item for explosive holes in December 2022 and January 2023 is 2,513 kg. This pvs value is still safe, because it is still below 5.0 mm/s and according to SNI 7572: 2010.

Monitoring of Cloud-based Air Quality using NodeMCU

Abstract: Air pollution has received a lot of attention in the modern world and has subsequently grown to pose a serious hazard to society. This research focuses on a device that can monitor air quality, ground vibration levels, and a form of fire safety alarm system for employees working in an industrial environment due to the urgency and quantity of air pollution. A WIFI-enabled ESP8266 NodeMCU microcontroller is used to implement this, and it is connected to air quality monitoring sensors MQ135 and DHT11 (Humidity and Temperature), as well as a geophone sensor to measure vibration levels in industrial settings and a flame sensor to protect workers from fire accidents. An alarm module is used with the buzzer. The sensor data is stored in NodeMCU and the data is analyzed and stored in the cloud platform and monitored on the BLYNK (an IoT platform) by interfacing the app with NodeMCU

EVALUATION OF GROUND VIBRATION AND AIR BLAST MEASUREMENTS INDUCED BY BLASTING IN A QUARRY MINE

The energy released during blasting in underground and surface mines for excavation purposes can cause flyrock, excessive level of ground vibration and air blast. In this study, ground vibration and air blast induced by blasting were measured and evaluated for a quarry mine in the Kangal district of Sivas province. Within the scope of this study, observations and measurements were made before, during, and after two blasting operations in a quarry mine to evaluate the environmental effects of blasting. The environmental effects of blasting were assessed by considering both the blasting parameters and the ground vibration and air blast measurement results.

Cold Collisions of Ro-Vibrationally Excited D2 Molecules.

The H2 + H2 system has long been considered a benchmark system for ro-vibrational energy transfer in bimolecular collisions. However, most studies thus far have focused on collisions involving H2 molecules in the ground vibrational level or in the first excited vibrational state. While H2 + H2/HD collisions have received wide attention due to the important role they play in astrophysics, D2 + D2 collisions have received much less attention. Recently, Zhou et al. [ Nat. Chem. 2022, 14, 658-663, DOI: 10.1038/s41557-022-00926-z] examined stereodynamic aspects of rotational energy transfer in collisions of two aligned D2 molecules prepared in the v = 2 vibrational level and j = 2 rotational level. Here, we report quantum calculations of rotational and vibrational energy transfer in collisions of two D2 molecules prepared in vibrational levels up to v = 2 and identify key resonance features that contribute to the angular distribution in the experimental results of Zhou et al. The quantum scattering calculations were performed in full dimensionality and using the rigid-rotor approximation using a recently developed highly accurate six-dimensional potential energy surface for the H4 system that allows descriptions of collisions involving highly vibrationally excited H2 and its isotopologues.

Foundation vibration and the added-building effect: Experimental evidence from a ground-borne vibration measurement campaign

As new buildings are constructed to accommodate the growing urban population, there is increasing use of sites close to both surface and underground railways. An important design consideration concerns the internal levels of perceptible vibration and re-radiated noise, which may have a negative impact on both the quality of life of occupants and the functioning of sensitive equipment. When considering this vibration serviceability, noise and vibration predictions are often made based on initial measurements of the free-field ground vibration, and by applying empirical relations available in the literature. Coupling loss, floor-to-floor and column-to-floor factors are all defined on the basis of data collected from a limited range of pre-existing buildings, and yet they are applied in practice on a wide range of soil–foundation–building systems. This paper presents the findings of a ground-borne vibration measurement campaign conducted during the construction of a 17-storey building above the Bakerloo line of the London Underground. Vibration levels are compared as the construction progresses over a two-year period, from the original brown-field site to the completion of the building, with the aim of identifying the so-called added-foundation and added-building effects. These effects, which refer to the attenuation or amplification of ground vibration levels resulting from the construction, are quantified in terms of coupling losses that are conceptually different from those found in vibration assessment procedures. Further results describing the variation in vibration levels within the completed building are compared with guideline values and their significance in a design context is discussed.

In Vitro and In Silico Vibrational-Rotational Spectroscopic Characterization of the Next-Generation Refrigerant HFO-1123.

Very short-lived substances have recently been proposed as replacements for hydrofluorocarbons (HFCs), in turn being used in place of ozone-depleting substances, in refrigerant applications. In this respect, hydro-fluoro-olefins (HFOs) are attracting particular interest because, due to their reduced global warming potential, they are supposed to be environmentally friendlier. Notwithstanding this feature, they represent a new class of compounds whose spectroscopic properties and reactivity need to be characterized to allow their atmospheric monitoring and to understand their environmental fate. In the present work, the structural, vibrational, and ro-vibrational properties of trifluorothene (HFO-1123, F2C = CHF) are studied by state-of-the-art quantum chemical calculations. The equilibrium molecular structure has an expected error within 2 mÅ and 0.2° for bond lengths and angles, respectively. This represents the first step toward the computation of highly accurate rotational constants for both the ground and first excited fundamental vibrational levels, which reproduce the available experimental data well within 0.1%. Centrifugal distortion parameters and vibrational–rotational coupling terms are computed as well and used to solve some conflicting experimental results. Simulation of the vibrational transition frequencies and intensities beyond the double harmonic approximation and up to three quanta of vibrational excitation provides insights into the couplings ruling the vibrational dynamics and guides the characterization of the gas-phase infrared spectrum experimentally recorded in the range of 200–5000 cm–1. The full characterization of the IR features is completed with the experimental determination of the absorption cross sections over the 400–5000 cm–1 region from which the radiative forcing and global warming potential of HFO-1123 are derived.

Spectral broadening of femtosecond pulses during SRS in hydrogen

It was shown that the spectral broadening of femtosecond laser pulses during stimulated Raman scattering (SRS) in hydrogen is determined by two nonlinear processes leading to phase modulation of the laser wave. Namely, the dependence of the refractive index of the gas on the intensity of laser radiation and the dependence of the refractive index on the ratio of the number of molecules at the ground and first vibrational levels of the hydrogen molecule, which changes during SRS.

Effect of Pile Driving on Ground Vibration in Clay Soil: Numerical and Experimental Study

In this study, peak particle velocity (PPV) values for driving three piles with diameters of 40 cm, 50 cm, and 70 cm in a clayey soil through the impact piling method are investigated by an experimental study and a numerical simulation. An experimental study is carried out on a scale of 1:20 of the operation. Numerical simulation is performed by using an axisymmetric model in PLAXIS 2D finite element software. Properties of the soil and the piles used in the experimental study are obtained from geotechnical tests and employed in the numerical simulation. The model has been verified by comparing the acquired PPV values with those measured in the experimental study. The results show a good agreement between the computed values and the experimental data. Moreover, measured peak particle velocities in the experimental study indicate that an increase in the diameter of the pile can increase the level of ground vibration. Some sensitivity analyses have been performed by numerical modeling to determine the effect of soil and pile properties on the changes of PPV. Also, increase in friction angle of the soil and pile diameter and reduction in elastic modulus of soil will increase the level of ground vibration. The results indicate that the amount of PPV at a distance of 100 cm is about 10.33% of the amount of PPV at a distance of 25 cm from the impact site to the pile with a diameter of 3.5 cm. In addition, this amount of reduction for pile with a diameter of 2.5 and 2 cm is equal to 8.31% and 12.77%, respectively.

Non-dissociative ionization cross section of the electronically excited H2 and D2 with atomic-limit principal quantum number n[formula omitted] 3 and 4

Electron-impact cross sections for non-dissociative ionization via the ground vibrational level (v=0) of the electronically excited H2 and D2 with atomic-limit principal quantum number n= 3–4, including HH¯1Σg+, B′1Σu+, D1Πu, GK1Σg+, I1Πg, J1Δg, O1Σg+, B′′B¯1Σu+, D′1Πu, P1Σg+, R1Πg, S1Δg, h3Σg+, e3Σu+, d3Πu, g3Σg+, i3Πg, j3Δg, f3Σu+, k3Πu, r3Πg, and s3Δg, are calculated by Gryzinski method in the present study. The cross sections for these states show a significant dependence on the threshold energy. The isotope effect of the cross sections for H2 and D2 is discussed. The computed cross sections of the electronic states with n= 1–4 from threshold up to 10 keV are fitted. The corresponding Maxwellian rate coefficients are derived from those cross sections with electron temperature from 1 to 10 eV.

Evaluation of Ground Vibration Resulting from a Heavy Vehicle Passing Over Transverse Rumble Strips: A Case Study in Kluang Road FT050

The transverse rumble strip (TRS) is one of the methods used to improve the driver's alertness to its driving and reduce their speed. However, the presence of a TRS causes unevenness on the road surface and may result in ground vibration when heavy vehicles passes it. This ground vibration may cause discomfort to the people living adjacent to the road. Therefore, there is a need to evaluate the level of ground vibration resulting from heavy vehicles passing over TRS especially on typical federal road in Malaysia which contains high percentage of fast-moving heavy vehicles. Ground vibration assessment study was conducted at federal road of Kluang-Batu Pahat Road (FT050) by using existing heavy vehicles in the traffic stream as study samples. ICP accelerometer and computer software Dewesoft7 have been used to measure and analyse the level of vibration generated. The results indicate heavy vehicles at a speed of 50 km/h, 33 km/h and 24km/h generate ground vibration level of 1.24 mm/s, 2.30 mm/s and 0.76 mm/s respectively. Other factors such as the weight of the heavy vehicles may involve in ground vibration generation mechanism as the results shown that there was no direct correlation between vehicle speed and level of ground vibration. All the generated ground vibration levels were found to be within the allowable limit set by Department of Environment Malaysia (DOE) standard guidelines.

Structural Dynamics, Noise and Vibration: Buildings Adjacent to Train Lines

In architecture and civil engineering there is a growing interest in the study of the dynamics of structures. The dynamic effects are due to various actions, but their influence is widened or reduced according to the design of the structure. Structures can be highly susceptible to the action of dynamic loads produced by the action of wind, earthquake, industrial activities, blasting activities, construction sites, road vehicles, trains, building services and human activities. Noise and vibration can have significant environmental impact on buildings and structures and can damage track components, crack roadways, unsettle foundations, affect sensitive equipment, impact human comfort and damage structures. Structure-borne noise and vibration can be a major and often overlooked consideration in the planning, design and operation of existing or new developments. A reliable, considered approach to assessing noise and vibration is needed to achieve outcomes that meet client expectations while maintaining on-going compliance with relevant standards and regulatory and planning requirements. The proposed paper will focus on a general overview of the structure-borne noise and vibration risks, associated with new developments that are adjacent to existing rail lines during the early design stages, from commercial and residential buildings to sensitive research facilities. It will further explain the general description of the design process, including problem descriptions, measurements of ground and structural vibration levels at the proposed site, vibration criteria, finite element analysis and provisions of the isolation system required to be considered at the building to achieve the relevant criteria.

Site-Resolved Imaging of Ultracold Fermions in a Triangular-Lattice Quantum Gas Microscope

Quantum gas microscopes have expanded the capabilities of quantum simulation of Hubbard models by enabling the study of spatial spin and density correlations in square lattices. However, quantum gas microscopes have not been realized for fermionic atoms in frustrated geometries. Here, we demonstrate the single-atom resolved imaging of ultracold fermionic $^{6}$Li atoms in a triangular optical lattice with a lattice constant of 1003 nm. The optical lattice is formed by a recycled narrow-linewidth, high-power laser combined with a light sheet to allow for Raman sideband cooling on the $D_1$ line. We optically resolve single atoms on individual lattice sites using a high-resolution objective to collect scattered photons while cooling them close to the two-dimensional ground vibrational level in each lattice site. By reconstructing the lattice occupation, we measure an imaging fidelity of ~98%. Our new triangular lattice microscope platform for fermions clears the path for studying spin-spin correlations, entanglement and dynamics of geometrically frustrated Hubbard systems which are expected to exhibit exotic emergent phenomena including spin liquids and kinetic frustration.