Kind Of Vibration Research Articles

Impacts of Whole-Body Vibration on Muscle Strength, Power, and Endurance in Older Adults: A Systematic Review and Meta-Analysis.

Randomized clinical trials (RCTs) were conducted to identify the effectiveness of whole-body vibration (WBV) on strength, power, and muscular endurance in older adults. However, the results of different studies are contradictory. To verify the impacts of the WBV on strength, power, and muscular endurance in older adults. The search was carried out in PubMed, Embase, CENTRAL, CINAHL, SPORTDiscus, Web of Science, LILACS and PEDro databases. Methodological quality was assessed using the PEdro scale. Meta-analysis calculations were performed using the standardized mean difference, comparing WBV with control groups and WBV with other types of exercise. Thirty-four studies were included in the current systematic review. Most studies (56%) had low methodological quality (PEDro score < 6). WBV, compared with control groups, has significant effects on muscle strength of knee extensors and flexors, lower limb extensors, and ankle plantar flexors. There were no differences between WBV and other types of exercise. Subgroup analyzes demonstrated that, in general, the significant results observed in the primary analyzes were not dependent on body position during vibration, kind of vibration, cumulative dose or magnitude of WBV. WBV was effective in increasing lower limb muscle strength. However, no significant results were observed for upper limb strength, lower limb power, and lower and upper limb muscle endurance in older adults. However, more studies are needed to better understand the physiological impacts of WBV in older.

アイドリング振動とエンジンシェイクを考慮した簡易モデルを用いたエネルギー伝達特性による分析

In automotive development, it is important to balance various phenomena with a simplified vehicle body model in the initial design phase. Additionally, idling vibration, engine shake, and road noise are phenomena that affect vehicle ride comfort. Since they have different exciting components and target frequencies, each simplified vehicle model examined in the past report is different. Therefore, it is necessary to represent of each phenomenon in a single vehicle model. Therefore, in recent years, much research has been done in initial design techniques called Model Based Development (MBD) and 1D CAE. We have studied using the Statistical Energy Analysis (SEA) for the initial design. Especially an energy transmissibility parameter of SEA which is called by coupling loss factor (CLF) is focused on describing the phenomenon for various kinds of vibration and noise problem. In this paper, a fundamental study is conducted to examine the balance of multiple phenomena in the initial design phase by the energy transmissibility. At first, a simplified vehicle model that represents each phenomenon is constructed. Next, the energy transmissibility is used to represent each phenomenon, and vibration reduction guidelines are obtained and verified through balance design. The obtained guidelines are then applied numerically to the actual vehicle to confirm vibration reduction.

Modeling and calculation of acoustic radiation of underwater stiffened cylindrical shells treated with local damping

Damping materials are widely used and playing an essential role in reducing the vibration and noise of various ships and underwater vehicles. In practical engineering, damping materials are often applied over the structural surface of ships and underwater vehicles. They are generally distributed not evenly in the whole area, but locally in some vital regions. The stiffened cylindrical shell is the most representative configuration for the main structure of underwater vehicles. Therefore, research on modeling and calculation of underwater acoustic radiation from stiffened cylindrical shells locally treated with damping has high practical value. This paper introduces a mixed analytical-numerical acoustic-vibration interaction method to achieve efficient calculation of the vibration and acoustic radiation from a locally damped cylindrical shell immersed in water. Two kinds of vibration and noise reduction measures are proposed for the damping treatment of a large-scale stiffened cylindrical shell structure. Calculation and analysis are carried out for both measures. The results can provide reference for developing the technology of reducing vibration and noise from ships and underwater vehicles via damping treatment.

Modulated Vibration Reduction Design for Integral-Slot Interior Permanent Magnet Synchronous Machines

In this article, a targeted step skewing of rotor segments scheme is proposed to reveal the modulated vibration reduction mechanism in integral-slot interior permanent magnet synchronous machines (IPMSMs). First, the vibration characteristics of a 72-slot/12-pole integral-slot IPMSM are investigated. The dominant vibration at specific frequency band is introduced. Then, in order to analyze the main source of vibration, the magnetic field modulation effect and radial force modulation effect are investigated in detail. The results show that the high-order radial force can excite large vibration by radial force modulation effect. This kind of vibration is defined as modulated vibration. Afterwards, the optimal shift angle and number of rotor segments are determined by comparison. Finally, the conventional and proposed 72-slot/12-pole integral-slot IPMSMs are manufactured to validate the theoretical analysis. The experimental results verify that the proposed method can effectively reduce the modulated vibration of the 72-slot/12-pole integral-slot IPMSM.

Dynamic Characteristics of Metal Seals in Roller Cone Bits

During the drilling process, the sealing performance of the roller cone bits is severely challenged by the complex downhole environment and frequent vibrations. In this paper, a comprehensive thermal–fluid–solid–dynamic multi-field coupling numerical model of new-generation single energizer metal seals (SEMS2) is developed. The instantaneous sealing performance of SEMS2 is studied under periodic vibration, instantaneous shock, and random vibration. Time-domain and frequency-domain changes in the sealing parameters with environmental pressures and rotational speeds under different vibrations are analyzed and compared. The results show that the liquid film distribution and lubrication state on the sealing end faces change constantly as the drill bit vibrates, which in turn affects the sealing performance of the SEMS2. The instantaneous leak rate fluctuates alternately between positive and negative under the three kinds of vibrations, aggravating the tendency of lubricant oil leakage and drilling mud invasion. With increasing environmental pressure and rotational speed, the fluctuation amplitudes of the maximum temperature increase, leakage rate, and friction torque under random vibration and instantaneous shock are significantly larger than those under periodic vibration. Our model and results have important theoretical significance for improving the design system of metal seals for drill bits.

Vertical dynamic interaction factors for offshore thin-walled pipe piles

With the development of offshore wind power in deep water, jacket foundations are increasingly used. These piles are always thin-walled pipe piles, whose dynamic interactions are different from onshore pile groups in several ways; for example, scour may develop around the piles, which may reduce a single pile’s impedance, the dynamic interactions between piles and the impedances of pile groups. Jacket foundations are usually exposed to marine dynamic loads and are likely to experience vertical and rocking vibrations. Both kinds of vibrations are related to the vertical dynamic interaction between piles, which are the focus of this study. The effects of soil rigidity, soil permeability, pile spacing, excitation frequency, scour type and scour depth on dynamic vertical interaction factors are studied in this paper by a rigorous semi-analytical method. Numerical results for parameter analysis are illustrated, and corresponding simplified closed-form equations to predict dynamic interactions are also deduced. The dynamic interaction factors are then used to study tripod piles and tetrapod piles. Dynamic interaction may increase or decrease the pile impedances, mostly depending on the pile spacing ratio and non-dimensional frequency, and closed-form equations are obtained to forecast the amplification or reduction.

Smart Highway with Green Energy

Abstract: Abstract: In today’s globalized world, road is that the suggests that to be a part of countries, cities, towns etc. In recent years all the previous technologies modified into new technology like icebox, TV, Washing Machine, cooler etc. All the items as modified however highways aren't modified. The "Smart Highway" is that the conception to create road roads smarter, safer, and a lot of energy economical for generating electricity exploitation alternative energy, wind energy, for charging the vehicle's exploitation these energies, for lighting, and for observation the condition of the road. The vehicle moving on roads generates great deal of energy in kind of vibration that is utterly wasted in addition they manufacture greenhouse gases that ultimately results in warming and depletes layer. So, there's a desire to create some revolutionary changes in conception of highways. We have a tendency to will use the vibration energy made by vehicles that is born-again into electricity. Equally by exploitation completely different techniques, wind energy, alternative energy and alternative form of inexperienced energies made on road as conjointly born-again into electricity. So, in this paper we have a tendency to be attempting to throw some lightweight on techniques of utilizing inexperienced energy on road in fruitful manner. Keywords: sensible highways, Vibration energy, alternative energy, Wind energy, semiconductor diode lightening

Origin of the weakly temperature-dependent thermal conductivity in ZIF-4 and ZIF-62

It is known that the temperature-dependent thermal conductivity of conventional crystals follows the classical 1/$T$ trend due to the dominant umklapp phonon-phonon scattering at high enough temperatures. However, the thermal conductivity of many crystalline metal-organic frameworks is very low and shows a weak temperature dependence when all the vibrational modes are occupied. By studying two metal-organic frameworks, i.e., zeolitic imidazolate framework-4 (ZIF-4) and crystal zeolitic imidazolate framework-62 (ZIF-62), we computationally prove that the ultralow thermal conductivity in ZIF-4 and ZIF-62 is resulting from the strong scattering among the vibrations due to the large mass difference between the metal atom and the organic sites and the large diffusion of organic sites. Unlike only propagating vibrational modes, i.e., phonons, existing in the conventional crystalline Si, our mean free path spectrum analysis uncovers that both propagating and nonpropagating anharmonic vibrational modes exist and contribute largely to thermal conductivity in ZIF-4 and ZIF-62. The obtained weak temperature dependence of thermal conductivity is found to stem from the temperature dependencies of those two kinds of vibrations. Our study provides a fundamental understanding of thermal transport in metal-organic frameworks and will guide the design of thermal-related applications, e.g., inflammable gas storage, chemical catalysis, and solar thermal conversion.

Efficient computation of coupled bending and torsion vibrations of slender structures with an axially moving eccentric load

AbstractFrequently slender structures are excited by moving loads and show the corresponding transient vibrations. A model is derived using a simply supported Bernoulli‐Euler beam and the coupled bending and torsion vibration equations are derived. An analytical solution of the decoupled partial differential equations is derived based on the eigenmode expansion considering the boundary and initial conditions. For the pure bending and the pure Saint‐Venant torsion the analysis is performed and the beam vibrations are calculated. The coupled bending and torsion deformations are computed using a modal transformation, where it is essential that the eigenmodes are the same for both kinds of vibrations. The resulting modal decoupling yields two separated ordinary differential equations in time with the assumed constant velocity of the axially moving excitation load. Closed form solutions are used which show a very good convergence. A transformation into the original coordinates results in the solutions of the coupled equations. The results are plotted in a dimensionless form. The evaluation and comparison with a suitable numerical calculation using a finite element model shows a good agreement of the results. It turns out that a fine discretization is necessary and the computation effort for computing the transient dynamic solution is very much higher.

Proposal of walking to prevent a fall of a planetary exploration legged rover using effect of loose soil caused by a propagation of vibration

In this study, a walking method which prevents to a fall of the planetary exploration legged rover is proposed. In the proposed walking method, the leg is sunk by giving vibration to the ground. The posture of the rover is changed in order to prevent to a fall of the rover by sinking leg. First of all, the relationship between the kind of vibration and the subsidence of the leg is confirmed. In this experimental result, the leg is shown to be easy to sink to the ground by giving vibration. Moreover, the larger vibratory force is, the easier the leg sinks to the ground. Finally, the legged testbed walks on the loose ground with a slope using the proposed walking method. In this experimental result, the testbed is difficult to fall down when it uses the proposed walking. Moreover, the angle of a slope that the testbed can walk becomes large by using the proposed walking.

Experimental Investigation on Self Compacting Concrete Using Recycled Aggregate

In the present work, an experimental investigation was carried out on self-compacting concrete made with various replacement levels of recycled coarse aggregate. The main aim of the experimental work is to know the suitability and effects of recycled aggregates in SCC. Self-Compacting Concrete is a type of concrete which does not need any kind of vibration or compaction. In the present experimental work, the behaviour of concrete made with recycled aggregates is evaluated and compared with the traditional concrete in which the coarse aggregate is replaced with recycled aggregate by 0%, 50%, and 100% respectively. Mechanical properties of the concrete were evaluated in its fresh and hardened conditions.

Design of Fixed-Wing and Multi-Copter Hybrid Drone System for Human Body Temperature Measurement during COVID-19 Pandemic

The purpose of this research is to conduct aerodynamics study and design a hybrid drone system of fixed-wing and multi-copter. The mission of this drone is to measure human body temperature during COVID19 pandemic. The specific aim of the drone is to fly and cover larger industrial areas roughly about 50 km2 with longer flying time than the conventional drone, of about 1.5 hours. The applications of the simulation software such as XFLR5 and ANSYS have a big impact in identifying areas that need to be improved for the drone system. XFLR5 software was used to compare the characteristics of different airfoils with highest lift over drag, L/D ratio. Based on the airfoil selection, it was found that NACA 4412 airfoil produces the highest L/D ratio. The detailed geometry of the drone system includes a fuselage length of 1.9 meters and wingspan of 2 meters. Moreover, 10 sheets of solar panels were placed along the wing for sustainable flight operation to cover wider areas of mission. The structural analysis was done on ANSYS to test the elastic stress, equivalent strain, deformation, factor of safety pressure as well as lift and drag forces under various operational conditions and payloads. The landing gear was analyzed for harsh landing. ANSYS Computational Fluid Dynamics (CFD) was utilized to study the aerodynamics of the drone at different parameters such as the velocities and angles of attack during the operation. This design ensures the stability of the drone during the temperature measurement phase. The best thermal-imaging camera for such purpose would be the Vue Pro R 336, 45° radiometric drone thermal camera with a resolution of 640 x 512 pixels. This camera has the advantage of a permanent continuous out focus that give the ability of taking measurements even if there was changing on the altitude or any kind of vibrations.

Investigation of hydrogen bond vibrations of ice

Despite its simple molecular structure, water is still a mystery to scientists. For the atomic and molecular vibrational modes of ice, as is well known, there are two kinds of vibrations: intra-molecular O—H stretching vibration and H—O—H bending vibration within the molecules and three kinds of molecular spatial rotations. However, thirty years ago, a high flux inelastic neutron scattering experiment showed that there are two distinct characteristic peaks in the far-infrared molecular translational vibration region of many ice phases. The origins of these peaks have not been determined till now. In this work, based on the CASTEP code, a first-principles density functional theory plane wave programme, the vibrational spectra as well as the vibrational normal modes of a series of ice phases are investigated. Two kinds of intrinsic hydrogen bond vibrational modes are first found in hydrogen-ordered ice Ic. Then it is found to be a general rule among ice family. Based on the ideal model, we prove that the two vibrational modes can be classified as four-bond vibration and two-bond vibration. There are many coupling modes in-between due to tetrahedral structure deformation under high pressure. Besides, there are also some optical vibrational modes with lower energy in the translational region, such as cluster vibrations and inter-plane vibrations. In Ice VII/VIII and XV/VI, each of which consists of two sublattices, there exist non-hydrogen bond vibrations. These molecular translational vibrations can explain all the far-infrared vibrational spectrum of ice phase, which makes up the last piece of the jigsaw puzzle for the molecular vibration theory of ice. The two vibrational modes do not exist in liquid water due to the collapse of the rigid tetrahedral structure. Thus, a window remains for ice resonance absorption with minimum energy loss in water. This theory is expected to be applicable to industrial deicing, food thawing, gas hydrate mining, and biomolecule frozen molding, etc.

Friction-Induced Vibration Suppression via the Tuned Mass Damper: Optimal Tuning Strategy

Friction-induced vibrations are a significant problem in various engineering applications, while dynamic vibration absorbers are an economical and effective tool for suppressing various kinds of vibrations. In this study, the archetypal mass-on-moving-belt model with an attached dynamic vibration absorber was considered. By adopting an analytical procedure, the optimal tuning of the absorber’s parameters was defined. Furthermore, the bifurcations occurring at the loss of stability were analytically investigated; this analysis illustrated that a properly chosen nonlinearity in the absorber’s stiffness permits controlling the supercritical or subcritical character of the bifurcation. However, a numerical analysis of the system’s dynamics, despite confirming the analytical results, also illustrated that the system’s global behavior is only slightly affected by the bifurcation character. Indeed, a dynamic vibration absorber possessing a perfectly linear restoring force function seems to provide the optimal performance; namely, it minimizes the velocity range for which stick–slip oscillations exists.

Study on Connection between Kind of Vibration and Influence of Ground for Leg Typed Rovers

Study on Connection between Kind of Vibration and Influence of Ground for Leg Typed Rovers

Experimental study of the nonlinear dynamics of a smooth and discontinuous oscillator with different smoothness parameters and initial values

The dynamic response of a nonlinear system is very sensitive to initial conditions., Both the irrational nonlinearity and the large displacement of a smooth and discontinuous (SD) oscillator have been studied in this paper. An experimental study has been conducted on a model of the SD oscillator with different initial conditions and smoothness parameters. Experimental results indicate that tiny variation in the initial displacement will lead different kinds of vibrations and the system exhibits a wide range of nonlinear dynamical phenomena with the change of smoothness parameters. All experimental results are in good conformity with the numerical simulation results.

New Study of Mgo Nps in Drilling Fluid to Reduce Stick-Slip Vibration in Drilling System

Stick-slip is kind of vibration which associated with drilling operation in around the bottom hole assembly (BHA) due to the small clearance between drill string &amp; the open hole and due to the eccentric rotating of string. This research presents results of specific experimental study that was run by using two types of drilling mud (Fresh water Bentonite &amp; Polymer), with/without Nanoparticle size materials of MgO in various ratios and computes the rheological properties of mud for each concentration [Yield point, plastic viscosity, Av, PH, filter loss (30 min), filter cake, Mud Cake Friction, Friction Factor]. These results then were used to find a clear effects of Nanoparticle drilling mud rheology on stick - slip strength by several perspectives through a special “Torque and Drag” software which simulate the torque amount expected on BHA during drilling a vertical well in different conditions using real drilling string design that usually used in Iraqi oil fields. Thus to mitigate or to prevent stick–slip and cure the sequence events that could happen to both of drilling string and the well, i.e. Bit/BHA wear, pipe sticking, borehole instability and low Rate of penetration. Our study concluded that there are good reduction in the torque from (2031lb-ft) to (1823lb-ft) using polymer mud and torque reduction from (4000lb-ft) to (3450lb-ft) using Fresh Water Bentonite, these results do not include any breaking in the satisfactory range of other mud rheology.

Asymptotic analysis of the high frequencies for the Laplace operator in a thin T-like shaped structure

We consider a spectral problem for the Laplacian operator in a planar T-like shaped thin structure Ωε, where ε denotes the transversal thickness of both branches. We assume the homogeneous Dirichlet boundary condition on the ends of the branches and the homogeneous Neumann boundary condition on the remaining part of the boundary of Ωε. We study the asymptotic behavior, as ε tends to zero, of the high frequencies of such a problem. Unlike the asymptotic behavior of the low frequencies where the limit problem involves only longitudinal vibrations along each branch of the T-like shaped thin structure (i.e. 1D limit spectral problems), we obtain a two dimensional limit spectral problem which allows us to capture other kinds of vibrations. We also give a characterization of the asymptotic form of the eigenfunctions originating these vibrations.

Eye-around vibration haptics on VR immersion improvement

Due to the inherent shortcomings of the hardware, the immersion of visual interaction between the user and the virtual reality (VR) equipment is greatly reduced. In this paper, effects of eye-around vibration haptics on improving the VR immersion were studied. The vibration was generated by flexible vibrators whose performance was evaluated by a laser vibrometer. Fitting the vibrators on the human eye area at different positions and derived by different waveforms and frequencies of the input signal, the effects of vibration on the human vision and comfort of the users were verified. Then, with the selected input signals and fitting locations, different kinds of vibration were applied on the eye area cooperating with virtual reality images or videos to evaluate the changes of immersion. Research results provide references to the modeling of eye tactile feedback and the design of relevant tactile device in improving the VR immersion.

Effects of optical and dielectric properties of l-cysteine doped tris thiourea zinc sulphate single crystals

The nonlinear optical single crystals of pure and l-cysteine amino acid doped Tris Thiourea Zinc Sulphate (TTZS) was synthesized and successfully grown by slow solvent evaporation technique. The present crystal was characterized by various analytical techniques. The lattice parameter values, cell volume and structure of the present crystal were identified by single crystal X-ray diffraction technique. The optical transparency and lower cut-off wavelength has been observed by UV–Vis spectrometer and further optical parameters were calculated. The FTIR analysis reveals the presence of functional groups and the kinds of vibrations. The NLO characteristics and laser damage threshold can be determined using Nd: YAG laser. The NLO efficiency and laser induced damage value of the L-cysteine doped tris thiourea zinc sulphate single crystal was found to be greater than pure TTZS crystal. In PL spectrum, sharp and narrow peaks are identified it denoted that the material having multi emission and it is suitable for applications in the light emitting diodes. The energy corresponding to the particular wavelength is also calculated. Growth nature of the title crystal was observed by etching analysis. The strength of the pure and doped crystals was determined using Vicker’s micro hardness test.