Vibrational Frequencies Research Articles

Effect of high-intensity vibration parameter on droplet transport characteristics in gas channel of proton exchange membrane fuel cell

In aerospace applications, proton exchange membrane fuel cells are subject to high-intensity vibration. Vibration has a substantial effect on water transport in fuel cells. However, there is a lack of research on the effects of multi-directional and high-intensity vibration conditions on fuel cells. In this study, the droplet transport characteristics in the gas channel under high-intensity vibration conditions are investigated for the first time. Moreover, the effects of vibration direction and vibration frequency on the droplet dynamic transport process are specifically studied. The droplet transport state, drainage performance, and pressure drop variation in the gas channel under different vibration conditions are analyzed and interpreted. The results show that low-frequency vibration in the longitudinal direction is more conducive to the droplet discharge, and the pressure drop undergoes a periodic change corresponding to the vibration frequency. Vertical vibration promotes droplet detachment from the gas diffusion layer surface, which contributes to the reduction in water coverage ratio on its surface, despite an increase in the channel pressure drop. Under the influence of horizontal vibration, droplets are more susceptible to adsorption on the channel sidewalls and turn into a liquid film, which leads to a longer discharge time and a reduction in pressure drop.

Investigation of Laser micro-textured triboelectric nanogenerator based self-powered vibration sensor for industry 4.0 application

Self-powered sensors detect a variety of crucial parameters for industrial processes without any external power source for Industry 4.0. It has capabilities to acquire, analyze, and make decisions on real-time data, these sensors are essential for the advancement of automated production systems and smart factories. In this regard, Triboelectric nanogenerators (TENGs) have potential to provide effective solution as self-powered vibration sensor for continuous monitoring of machine tools. Different techniques have been used to enhance the performance of TENG such as material doping, chemical etching, ion injection, etc. However, laser surface texturing is a low-cost, contact less, efficient technique which can be used for improving the response of TENG-based self-powered vibration sensors. In this context, Laser Induced Backside Texturing is a laser micro texturing approach to improve the electrical performance. It induces waviness and surface roughness, which leads to increased surface charge density and triboelectrification capabilities. In this work, laser micro texturing was performed using with 405 nm wavelength semiconductor diode laser to generate line pattern texture on the Fluorinated Ethylene Propylene (FEP). Laser textures TENG (LT-TENG) was developed with laser textured FEP as tribonegative material and pristine Aluminium as tribopositive material, the open-circuit voltage, short-circuit current and power density achieved 23 %, 41 %, and 47 % enhancement respectively, generating 794 V, 44 µA, and 2371.6 µW/cm2. This increase in output leads to an increased sensitivity of the sensor. When mounted on the machines, LT-TENG was able to detect their working state, vibration frequency, and harmonics i.e. 46, 92, 184 Hz for the vacuum pump and 140, 280, 410 Hz for the heat gun. These detected vibration frequencies, and their harmonics were similar to the frequencies detected by the commercial accelerometer (CTC AC115), confirming potential use of LT-TENG as a low-frequency vibration sensor. The developed LT-TENGs was integrated with the Internet of Things (IoT) supported microcontroller, which collects real-time data for continuous monitoring and analysis for machine health monitoring in smart devices.

Performance of elastic ball screen-cleaning device based on DEM-MBD coupling simulation

In seed breeding, the vibrating screen used for pre-sowing grading parental seeds often has the problem of poor self-purification rate. Using elastic balls to clean the plugging seeds and ensure the self-purification of the screen is a viable technical solution. To clarify and improve the operating performance of the elastic ball particles, a DEM-MBD coupling simulation model of the elastic ball screen-cleaning device was established in this study, and a numerical simulation analysis of the complex motion process was carried out. The mechanism of action of the elastic ball was explained more completely from the aspects of excitation force and energy transfer. Through the Plackett-Burman test, it was determined that the vibration frequency has the most significant effect on the excitation force. Multiple linear regression analysis was performed on each factor and the mathematical relationship equation. It was found that when the maximum excitation force was greater than 7 N and the average excitation force was greater than 2 N, the self-purification rate was greater than 95%. The self-purification rate was then increased to 99.81% by variable frequency tests. The variable frequency achieved better self-purification effect.

Statistics of kinetic and thermal energy dissipation rates in vibrational turbulent Rayleigh–Bénard convection with rough surface

In this paper, the statistical properties of the kinetic εu and thermal εθ dissipation rates in two-dimensional (2D) turbulent Rayleigh–Bénard convection (RBC) are studied by using the thermal lattice Boltzmann method (LBM). A series of direct numerical simulations (DNS) are implemented in a square cell with the unit aspect ratio for the Rayleigh number Ra = 108 and Prandtl number Pr = 4.38. The roughness height h* and vary the vibration frequency ω* from 0 to 1000 are fixed in the vibrational RBC with rough plates to explore their effect on the kinetic and thermal dissipation rates. The global features indicate that the εu and εθ are more intense in the regions with high gradients of velocity and temperature, which is in good agreement with the previous work. The scalings of Nu∼ω *0.55±0.1 and Re∼0.59±0.2 are proposed between the ensemble averaged Nusselt number Nu and Reynolds number Re. The probability density functions (PDFs) of both logarithmic kinetic dissipation rate lg εu and thermal dissipation rate lg εθ are not conformed to the log-normal distributions. Through the analysis of the time-averaged εu and εθ vertical profiles, it is further demonstrated that the local dissipation rates from the boundary layer region are still the major contribution in the vibrational RBC with rough plates.

Similarities and Differences of Hydridic and Protonic Hydrogen Bonding.

Ab initio calculations were employed to investigate the interactions between selected electron-donating groups, characterized by M-H bonds (where M represents a transition metal and H denotes a hydridic hydrogen), and electron-accepting groups featuring both σ- and π-holes. The study utilized the ωB97X-D3BJ/def2-TZVPPD level of theory. Hydridic hydrogen complexes were found in all complexes with σ- and π-holes. A comparative analysis was conducted on the properties hydridic H-bond complexes, presented here and those studied previously, alongside an extended set of protonic H-bonds complexes. While the stabilization energies changes in M-H bond lengths, vibrational frequencies, intensities of the spectral bands, and charge transfer for these complexes are comparable, the nature of hydridic and protonic H-bonds fundamentally differ. In protonic H-bond complexes, the main stabilization forces arise from electrostatic contributions, while in hydridic H-bond complexes, dispersion energy, is the primary stabilization factor due to the excess of electrons and thus larger polarizability at hydridic H. The finding represents an important characteristic that distinguishes hydridic H-bonding from protonic H-bonds.

Natural Frequency Transmissibility for Detection of Cracks in Horizontal Axis Wind Turbine Blades.

Defects on horizontal axis wind turbine blades are difficult to identify and monitor with conventional forms of non-destructive examination due to the blade's large size and limited accessibility during continuous operation. This article examines both strain and acceleration transmissibility as methods of continuous damage detection on wind turbine blades. A scaled 117 cm offshore wind turbine blade was first designed, 3D printed, and modelled numerically in ANSYS. Transverse cracks were deliberately introduced to the blade at 10 cm intervals along its leading edge. Subsequent changes in the transmissibility, relative to an undamaged baseline model, were measured using different variable combinations at the blade's first three natural frequencies. Experimental results indicated that strain transmissibility was able to locate a 1.0 cm defect at a range of 70-110 cm from the blade hub using the amplitudes of the first natural frequency of vibration. The numerical model was able to simulate the strain experimental results and was determined to be valid for future defect characterization. Acceleration transmissibility was unable to experimentally identify defects sized at 1.0 cm and below but was able to identify 1.0 cm sized defects numerically. It was concluded that transmissibility is viable for continuous damage detection on blades but that further research into other defect types and locations is required prior to conducting full-scale testing.

Evaluation of infrared thermography, arterial Doppler ultrasound, and Doppler echocardiography in healthy adult dogs exposed to a single session of Whole-body vibration at different frequencies

This study aimed to evaluate the infrared thermography, arterial Doppler ultrasound, and Doppler echocardiography in healthy adult dogs exposed to a single Whole-body vibration (WBV) at different frequencies. Sixteen (16) healthy crossbreed dogs males of ages 1 to 5 years, weighing 16.3 to 24.5 kg were enrolled in the study. The dogs were exposed to a single WBV session at frequencies of 30 Hz (5 min), 40 Hz (5 min), and 50 Hz (5 min) with intervals between each frequency exposure of 10 min. The cutaneous temperature, arterial Doppler ultrasound, and Doppler echocardiography were evaluated 10 min before the WBV session, between each frequency, and 1 min after the last frequency. The cutaneous temperature of the regions of the superficial gluteal muscle and biceps femoris muscle of both hind limbs was obtained with an infrared camera. Resistive indexes of carotid and femoral arteries were determined using Doppler ultrasound, and Doppler echocardiography was used to assess the end-systolic volume and end-diastolic volume, heart rate, aortic blood flow velocity, and pulmonary artery flow velocity. Clinical parameters, complete blood count, and serum biochemical (alanine aminotransferase, creatinine, and creatine phosphokinase) were evaluated 10 min before and 60 min after the end of the WBV session. Statistically significant differences were not found in any of the variables among the time points. In conclusion, the protocol of increasing vibration frequencies (30, 40, and 50 Hz) at short-period WBV can be considered appropriate since no change occurred in the parameters evaluated.

ANISOTROPY AND MECHANICAL CHARACTERISTICS OF ULTRA-HIGH PERFORMANCE CONCRETE AND ITS INTERPENETRATING PHASE COMPOSITE WITH TRIPLY PERIODIC MINIMAL SURFACE ARCHITECTURES

Abstract This work numerically explores the anisotropy, impact phase wave propagation, buckling resistance, and natural vibration of ultra-high performance concrete (UHPC) and UHPC-steel interpenetrating phase composite (IPC) with triply periodic minimal surfaces (TPMSs), including sheet and solid Gyroid, Primitive, Diamond, and I-WP. The experiment is conducted verifying the accuracy of the numerical model in terms of Young's modulus of polylactic acid (PLA)-based TPMS lattices and PLA-cement IPCs with TPMS cores, with the highest percent difference of 15% found for IPCs and 17% found for lattice. The results indicate that UHPC material with sheet Gyroid exhibits the least extreme anisotropy in response to the varying orientation among other lattices regardless of the change of solid density, making it the ideal candidate for construction materials. Interestingly, compared to UHPC-based TPMS lattice, IPCs possess a much smaller anisotropy and exhibit almost isotropy regardless the variation of solid density and TPMS topology, offering a free selection of TPMS type to fabricate IPCs without much care of anisotropy. The phase wave and buckling resistance of UHPC- and IPC-based beams with TPMSs nonlinearly decrease with a drop of TPMS solid density, but it is the almost linear pattern for the case of natural vibration frequency. UHPC material and IPC with sheet Gyroid lattice are found to possess the lowest phase wave velocity and exhibit the least anisotropy of wave propagation, showing it as an ideal candidate for UHPC material to suppress the destructive energy induced by the external impact.

High density ferroelectric charges enabled droplet vibration nanogenerator with extraordinary output

Droplet vibration nanogenerator is a promising technology that can transform kinetic energy into electric energy. In this paper, a vibration droplet nanogenerator based on lead zirconate titanate (PZT) (PZT-VDNG) is proposed, which utilizes the change in double electron layer area at the droplet/PZT interface, hence an extraordinary charge variation, induced by mechanical vibrations. Our approach innovatively combines a high fixed surface charge density with ionic solutions to significantly enhance energy conversion efficiency. A theoretical model of the PZT-VDNG is established, showing excellent consistence with the experimental results. The energy conversion efficiency and its correlation with the materials involved, device structure and circuits used, are investigated in detail. Under the optimal conditions of a vibration frequency of 5 Hz, an amplitude of 2 mm, and a droplet size of 40 μL, a short-circuit current output of 31.43 μA and an open-circuit voltage of 1.5 V are obtained by a single vibration of a droplet, respectively, 111 and 37.5 times larger as compared to those from a VDNG with PTFE polymer layer. This marks a significant leap in the efficiency and potential applications of vibration nanogenerators.

Ab initio exploration of low-lying electronic states of linear and bent MNX+ (M = Ca, Sr, Ba, Ra; X = O, S, Se, Te, Po) and their origins.

High-level multireference and coupled cluster quantum calculations were employed to analyze low-lying electronic states of linear-MNX+ and side-bonded-M[NX]+ (M = Ca, Sr, Ba, Ra; X = O, S, Se, Te, Po) species. Their full potential energy curves (PECs), dissociation energies (Des), geometric parameters, excitation energies (Tes), and harmonic vibrational frequencies (ωes) are reported. The first three chemically bound electronic states of MNX+ and M[NX]+ are 3∑-, 1Δ, 1∑+ and 3A″, 1A', 1A″, respectively. The 3∑-, 1Δ, 1∑+ of MNX+ originate from the M+(2D) + NX(2Π) fragments, whereas the 3A″, 1A', 1A″ states of M[NX]+ dissociate to M+(2S) + NX(2Π) as a result of avoided crossings. The MNX+ and M[NX]+ are real minima on the potential energy surface and their interconversions are possible. The M2+NX-/M2+[NX]- ionic structure is an accurate representation for their low-lying electronic states. The Des of MNX+ species were found to depend on the dipole moment (μ) of the corresponding NX ligands and a linear relationship between these two parameters was observed.

Probing the Effects of Size and Charge on the Monohydration and Dihydration of SiF5- and SiF62- via Comparisons with BF4- and PF6.

This study systematically examines the interactions of the trigonal bipyramidal silicon pentafluoride and octahedral silicon hexafluoride anions with either one or two water molecules, (SiF5-(H2O)n and SiF62-(H2O)n, respectively, where n = 1, 2). Full geometry optimizations and subsequent harmonic vibrational frequency computations are performed using the CCSD(T) ab initio method with a triple-ζ correlation consistent basis set augmented with diffuse functions on all non-hydrogen atoms (cc-pVTZ for H and aug-cc-pVTZ for Si, O, and F; denoted as haTZ). Two monohydrate and six dihydrate minima have been identified for the SiF5-(H2O)n systems, whereas one monohydrate and five dihydrate minima have been identified for the SiF62-(H2O)n systems. Both monohydrated anions have a minimum in which the water molecule adopts a symmetric double ionic hydrogen bond (DIHB) motif with C2v symmetry. However, a second unique monohydrate minimum has been identified for SiF5- in which the water molecule adopts an asymmetric DIHB motif along the edge of the trigonal bipyramidal anion between one axial and one equatorial F atom. This Cs structure is more than 2 kcal mol-1 lower in energy than the C2v local minimum at the CCSD(T)/haTZ level of theory. While the interactions between the solvent and ionic solute are quite strong for the monohydrated anions (electronic dissociation energies of ≈12 and ≈24 kcal mol-1 for the SiF5-(H2O)1 and SiF62-(H2O)1 global minima, respectively), these values are nearly perfectly doubled for the dihydrates, with the lowest-energy SiF5-(H2O)2 and SiF62-(H2O)2 minima exhibiting dissociation energies of ≈24 and ≈47 kcal mol-1, respectively. Structures that form hydrogen bonds between the solvating water molecules also exhibit the largest shifts in the harmonic OH stretching frequencies for the waters of hydration. These shifts can exceed -100 cm-1 for the SiF5-(H2O)2 minimum and -300 cm-1 for the SiF62-(H2O)2 minimum relative to an isolated H2O molecule at the CCSD(T)/haTZ level of theory. This work also corrects the OH stretching frequency shifts for two dihydrate minima of PF6- that were previously erroneously reported ( J. Phys. Chem. A 2020, 124, 8744-8752, DOI: 10.1021/acs.jpca.0c06466).

Improving the efficiency of channel evaluation during high-speed data transmission in underwater acoustic communication with OFDM

Problem statement. The organization of noise-resistant wireless underwater acoustic communication is not a simple and solved task. One of the main problems is the multipath propagation of a sound acoustic wave as a result of re–reflections from the seabed surface and a change in the frequency of signal vibrations when the receiver and transmitter move relative to each other. Thus, finding a channel evaluation solution that can improve the quality of communication is an urgent task for developers of underwater acoustic communication systems. Purpose. To consider the possibility of developing effective methods for processing underwater acoustic communication signals with high noise immunity by evaluating the communication channel. Results. The possibility of using an adaptive filter with a sliding window to evaluate the channel during high-speed data transmission in underwater acoustic communication is shown. The simulation results showed that the proposed adaptive filter with a sliding window surpasses the normalized adaptive filters in terms of the BER bit error and wins over additive filters with an exponential window in reducing the number of mathematical operations. When modeling wireless acoustic communication systems with OFDM, error-free data transmission with a spectral efficiency of 0.33 bits/s/Hz was achieved. Practical significance. The obtained results can be used to improve the wireless transmission of data in underwater acoustic communication due to the proposed algorithm of the adaptive filter.

Nonlinear free vibration analysis of multi-directional functionally graded porous sandwich plates

Multi-directional functionally graded materials (MFGMs) have attracted significant research attention due to their advantages over one-directional FGMs. In MFGM structures, material properties can be tailored to grade in the required direction, overcoming practical problems like excessive temperature gradients or extreme deflections. This paper aims to investigate the nonlinear free vibration of MFG porous sandwich plates to improve their application in sandwich structures. The two outer layers of the plates are composed of three-directional functionally graded material (3D-FGM), with a bi-directional functionally graded material (2D-FGM) core layer. Additionally, the porosity distribution within the material matrix is assumed to be either even or uneven across the plate thickness. A higher-order finite element model based on Shi's plate theory and the von Kármán assumption is developed. The nonlinear free vibration frequencies are determined through the maximum vibrational amplitude using an iterative algorithm with a displacement control strategy. The accuracy and effectiveness of the proposed model are demonstrated through a comparison with published data. The results show that the vibration response is significantly influenced by various parameters. Specifically, increasing the material gradient indexes in the thickness direction enhances the frequency ratio, while increasing the gradient indexes in the length and width directions reduces it. Higher porosity coefficients in the core layer decrease the frequency ratio, whereas higher pore coefficients in the outer layers increase it. The additional knowledge gained from this study can help with future analysis and design procedures related to the nonlinear responses of these complex structures.

A fast and efficient pseudo-direct identification method for orthotropic elastic properties of multi-layered composite plates

New types of laminated composites are continuously being developed to meet various requirements involved in engineering applications. Before mass production of these new composite materials can take place, it is necessary to identify their elastic properties. Although current identification methods based on vibration tests and optimization algorithms are highly accurate, their high computation cost is a drawback. To address this issue, this paper proposes a new method to identify orthotropic elastic properties of multi-layered composite plates. The proposed method is based on the Modal Stability Procedure, using the experimental vibration frequencies and corresponding numerical mode shapes of structures. It converges after only two or three iterations without requiring an optimization algorithm. Therefore, the computational cost of the proposed method is significantly lower than that of optimization-based methods. The effectiveness and robustness of this method are demonstrated through three examples with different material, stacking sequences, and geometries including curved plate.

An Adaptive Elastic Support Seat-Based Magnetorheological Elastomer for Human Body Vibration Reduction.

This paper introduces an electromagnetic structure utilizing the controllable mechanical properties of magnetorheological elastomer (MRE) materials through magnetic flux. An adaptive elastic foundation composed of these materials is explored for vibration reduction and frequency modulation. This study investigates these effects using both a single-mass model and a coupled human-seat model. For objects supported by the adaptive elastic foundation, increasing the magnetic flux enhances the stiffness and damping, thereby significantly reducing the peak response while slightly increasing the resonance frequency. Strategies such as increasing the magnetic flux, reducing the object mass, and minimizing the system's degrees of freedom and internal damping contribute to enhancing the vibration reduction and frequency modulation in the adaptive elastic foundation. The simulation results indicate that for a seated human (weighing between 72.4 kg and 88.4 kg), the adaptive elastic foundation reduces the head peak response by approximately 15.7% and increases the resonance frequency by approximately 3.4% at a magnetic flux of 138 mT.

Analysis of unsteady internal flow characteristics in axial pump with varying number of blades using computational modelling and vibration techniques

Axial pumps were extensively applied in many varying applications because of their large flow and low head. In this research investigation, the comparative analysis of the findings unveiled that the predominant source of hydraulic-induced vibration in the pump stemmed from pressure pulsations at the impeller inlet. Notably, similar patterns in amplitude were observed as flow rates increased. Furthermore, time-domain analysis confirmed that pressure pulsations and vibrations are highly correlated under high flow rates. Pressure pulsation's Frequency-domain analysis also revealed that it was a multiple of shaft frequency and changed from one multiple to three multiples of vibration. While analyzing the flow rate characteristics pertaining to pressure pulsation and vibration, it was determined that pressure pulsations at the impeller inlet had the potential to generate frequency components across a broad spectrum, encompassing both low and high flow rates, as well as their respective multiples. This phenomenon was particularly pronounced in regions characterized by unstable and high flow rates. Vibration ingredients likely influenced by pressure pulsation at the impeller inlet could be as low as design flow rates and as high as high flow rates. A vibration frequency with a multiple did not seem to be influenced by pulsating pressure at the impeller entrance. The present study focuses on investigation of flow behaviors in an axial pump with varying numbers of blades. It is an important geometric parameter that significantly affects the pump's performance. Therefore, the dynamic flow patterns in a pump, considering changed flow and impeller blade configurations, are investigated by employing the sliding mesh technique in combination with SST (k-ω) turbulence model. The numerical results exhibit a commendable alignment with the existing experimental data, enhancing the predictive accuracy of pump performance. Qualitative analyses encompass static pressure, shear stress, and various velocity components. Concurrently, quantitative investigations delve into pressure fluctuations and average pressure across a spectrum of operating conditions and impeller blade configurations. These comprehensive findings underscore the substantial influence of the impeller blade on pressure, velocity magnitudes radial, axial, tangential shear stress, average pressure within the system.

Numerical modeling of heat flux in ultrasonic-assisted grinding of difficult-to-cut materials with a pressurized lubrication system

The temperature measurement during grinding process is difficult due to work–wheel interactions and nearby coolant layers. Surface integrity also gets affected by the grinding burns caused due to high heat generation. Therefore, the theoretical temperature estimation could provide prior detection of grinding burns. This article presents an analytical model to predict the heat flux in pressurized lubricated ultrasonic-assisted surface grinding of Nimonic 80 A using Cubic Boron Nitride (cBN) grinding wheel (vitrified grinding bond, grit 80/100, concentration 100%). In this process, the high frequency of ultrasonic vibration and low amplitude is employed to vibrate the workpiece. In the current modeling approach, the motion analysis of grains has been estimated initially, which provided the effective grinding force. This effective grinding force was then utilized to obtain the analytical model of heat flux. Finally, the model was formulated by considering the effect of heat conducted into the material and heat released due to the lubrication system. The established model comprised the effects of lubricating and machining parameters such as dynamic viscosity of cutting fluid, pressure, diameter and length of cutting fluid pipes, width of cut, frequency, speed of table, amplitude, depth of cut and speed of the wheel. This numerical model revealed affirmative results substantiated by experimentally procured data. This developed model can add to the direction of sustainable grinding approach.

Unveiling the molecular insights of 2-(carboxymethyl) benzoic acid: A density functional theory approach towards structural and biological attributes

Nowadays density functional theory (DFT) is one of the best methods to explore the vibrational modes and structure of the biological system. Quantum mechanical calculations are performed using gas phase and different solvents (DMSO, methanol and water). The derived global reactive parameters, structural and topological study provides the clear insight of the 2-(Carboxymethyl) benzoic acid. Depth studies of DFT proves the existence of hydrogen bonds between donor and acceptor in the compound, which is supportive for the biological applications. In this paper, different experimental and computational simulated FT-IR, FT-Raman, UV–Vis spectral studies are used to explicate vibration assignments of the 2-(Carboxymethyl) benzoic acid. Experimentally observed vibrational frequency is compared with theoretically simulated spectrum. B3LYP method with 6–311++G (d, p) basis set is used in DFT to optimize the 2-(Carboxymethyl)benzoic acid structure. The most stable lower energy conformer is identified using potential energy surface (PES) analysis using Gaussian 16 W software. ESP, HOMO-LUMO, NBO, and QTAIM calculations have evinced an adequate electronic characterization of 2-(Carboxymethyl) benzoic acid. Further, van der Waals and steric interactions among 2-(Carboxymethyl) benzoic acid have been discussed with the help of RDG study. Hirshfeld surface studies establish the existing various interaction among molecules and total packing arrangement of the crystal structure. Due to the high biological activity score, 2-(Carboxymethyl) benzoic acid is a good therapeutic candidate. Lipophilicity analysis of 2-(Carboxymethyl)benzoic acid clearly explicates the bioactivity properties and its effective drug applications. Further, molecular docking investigates that the compound can be used as anticancer medication. The detailed DFT study of the 2-(Carboxymethyl) benzoic acid justified its biological applications of the present communication. The calculated NLO parameters of 2-(Carboxymethyl)benzoic acid evidenced for good efficacy in diverse filed application has been discussed.

Exploring the nonlinear optical characteristics of supersalt-decorated graphyne via DFT analysis: unveiling quantum insights into light-matter interaction

In this comprehensive study, we explore into the nonlinear optical (NLO) properties of graphyne (GRY) and its compounds decorated with a super salt (OLi3BeF3), namely GRY@SS1, and GRY@SS2) using the rB3LYP/6−31G(d,p) DFT method. Our findings reveal a substantial enhancement in the electron transfer properties of decorated compounds compared to the pristine GRY surface. This enhancement is evidence by the reduction in the bandgap energies (Eg) from 3.52 eV to 1.68 eV and remarkable boost in maximum absorption ( λmax) from 372.66 to 807.73 nm. Noteably, GRY@SS2 exhibits a significant increase in linear polarizability ( α0 ) (538.18 au), first hyperpolarizability ( β0 ) (3872.76 au), and second hyperpolarizability ( γ0 ) (1.00 × 106) due to reduced excitations energies compared to the GRY ( α0 = 448.61, β0 = 0.14 and γ0 = 5.97 × 105 au). NBO charges show that electrons are transferring from the dopant (supersalt) to the GRY sheet. Furthermore, Non-covalent interactions (NCl), iso-surface, infrared (IR), 1H NMR, and 13C NMR studies have been conducted to provide insights into the nature of interactions, vibrational frequencies, and structural-functional aspects of GRY and GRY@SS1, and GRY@SS2. According to TD-DFT calculations, all compounds demonstrate superior vertical ionization potential, UV–vis absorbance, HOMO–LUMO characteristics, as well as interaction energies. Our results underscore the potential of these compounds as valuable NLO materials, particularly highlighting the promising prospects of GRY@SS2.

Investigation of carbon black nanoparticle modified cementitious composites for sensing dynamic vibro-acousto signals

Current application of intrinsic piezoresistivity of cementitious materials filled with nano conductive substances is limited in sensing quasi-static signals featuring low-frequency and high-amplitude. Its self-sensing capacity for low-amplitude and high-frequency vibro-acousto signals is not fully investigated. In this study, different doses of carbon black nanoparticles (CBN) are added in cementitious materials and their conductivity is measured to find the percolation zone where the tunnelling effect dominates the conduction mechanism, followed by the characterization of their piezoresistivity. Consequently, impact forces and crack-related energy release, which generate dynamic signals in the range of vibrational and acoustic frequencies, are individually utilized to test the behaviour of such materials for sensing dynamic vibro-acousto signals. The results show that CBN-modified cementitious composites which show excellent piezoresistivity behaviour are capable of locally self-sensing dynamic signals as sensors. Comparing with piezoelectrical sensors, the developed sensor shows higher sensitivity to crack initiation.