The effectiveness of vibration damper attached to the cable due to wind action

In the paper the analysis of vibration of cable with attached damper is performed. Source of vibrations comes from the wind. The level of reduction of vibrations is also analysed. Damper attached to the cable is characterized by mass, stiffness and damping ratio. The paper also presents the equations of motion for the cable with damper, taking into account the initial parameters: cable cross-section and the location of the damper. The analysis is performed in time domain. It is discussed that in real situations the different types of cable vibration due to their amplitudes and frequencies is met: short-term oscillations of high amplitude, caused by a single impulse force, called bouncing cable, low amplitude and low wave length and the high frequency, called aeolian vibration, large oscillation amplitude, long wave length and low frequency, called galloping or dancing cables

Tramadolium picrate

In the title salt {systematic name: [2-hy­droxy-3-(3-meth­oxy­phen­yl)cyclo­hexyl­meth­yl]dimethyl­aza­nium 2,4,6-trinitro­phenol­ate}, C16H26NO2 +·C6H2N3O7 −, the cation is protonated at the N atom. The cyclo­hexane ring adopts a chair conformation with the hy­droxy substituent in an axial position. In the crystal, O—H⋯O and N—H⋯O hydrogen bonds link the cations and anions into supra­molecular chains along [100]

(E)-3-(4-Chloro­phen­yl)-1-(1-naphth­yl)prop-2-en-1-one

In the title compound, C19H13ClO, the benzene ring and the naphthalene system, are twisted by 12.3 (3) and 36.1 (2)°, respectively, and in opposite directions with respect to the central propenone bridge. The bond-angle pattern within the benzene ring is influence by both substituents; these influences are almost additive. In the crystal, the molecules are linked by C—H⋯O and C—H⋯Cl inter­actions

(2E)-1-(4-Bromo­phen­yl)-3-(4-fluoro­phen­yl)prop-2-en-1-one

The title compound, C15H10BrFO, is isostructural with (2E)-1-(4-chloro­phen­yl)-3-(4-fluoro­phen­yl)prop-2-en-1-one [Qiu et al. (2006 ▶). Acta Cryst. E62, o3525–o3526], but the structures of other dihalogen analogues, without fluorine, are different, although they are also isostructural within the series. The mol­ecule is approximately flat, the dihedral angle between the ring planes being 8.49 (13)°. In the crystal structure, inter­molecular C—H⋯O, C—H⋯F and C—H⋯Br hydrogen bonds link mol­ecules into V-shaped ribbons running parallel to [101] and stacked with an inter­planar distance of approximately 3.53 Å (centroid–vcentroid distance = 3.857 Å).

(1RS,6SR)-Ethyl 4,6-bis­(4-fluoro­phen­yl)-2-oxocyclo­hex-3-ene-1-carboxyl­ate

In the crystal structure of the title compound, C21H18F2O3, the cyclo­hexene ring has a slightly distorted sofa conformation; the two benzene rings are inclined by 76.27 (8)° and their planes make dihedral angles of 16.65 (10) and 67.53 (7)° with the approximately planar part of the cyclo­hexenone ring [maximum deviation 0.044 (2) Å, while the sixth atom is displaced by 0.648 (3) Å from this plane]. In the crystal, weak inter­molecular C—H⋯O, C—H⋯F and C—H⋯π inter­actions join mol­ecules into a three-dimensional structure

(1RS,6SR)-Ethyl 4-(4-chloro­phen­yl)-6-(4-fluoro­phen­yl)-2-oxocyclo­hex-3-ene-1-carboxyl­ate toluene hemisolvate

In the crystal structure of the title compound, C21H18ClFO3·0.5C7H8, the toluene solvent mol­ecules occupy special positions on centres of symmetry, and consequently are disordered across this site. The cyclo­hexene ring has a slightly distorted sofa conformation; the two benzene rings are inclined by 72.90 (7)° and their planes make dihedral angles of 30.09 (10) (chloro­phen­yl) and 88.13 (6)° (fluoro­phen­yl) with the approximately planar part of the cyclo­hexenone ring [maximum deviation from plane through five atoms is 0.030 (2) Å, the sixth atom is 0.672 (3)Å out of this plane]. Weak inter­molecular C—H⋯O and C—H⋯X (X = F, Cl) inter­actions join mol­ecules into a three-dimensional structure. Also, a relatively short and directional C—Cl⋯F—C contact is observed [Cl⋯F = 3.119 (2) Å, C—Cl⋯F = 157.5 (2)° and C—F⋯Cl 108.3 (2)°]. The solvent mol­ecules fill the voids in the crystal structure and are kept there by relatively short and directional C—H⋯π inter­actions

(1RS,6SR)-Ethyl 4-(2,4-dichloro­phen­yl)-6-(4-fluoro­phen­yl)-2-oxocyclo­hex-3-ene-1-carboxyl­ate

There are two symmetry-independent mol­ecules in the asymmetric unit of the title compound, C21H17Cl2FO3. Both these mol­ecules are very similar: the normal probability plots for bond lengths, angles and even for torsion angles show that the differences are of a statistical nature. A pseudocentre of symmetry is located between the symmetry-independent mol­ecules at [0.245 (1), 0.535 (19), 0.909 (1)]. The cyclo­hexene rings have slightly distorted sofa conformations in both mol­ecules and the two benzene rings are inclined by dihedral angles of 61.33 (14) and 62.85 (14)°. In the crystal, relatively short inter­molecular C—H⋯O inter­actions join mol­ecules into homomolecular (i.e. ⋯AAA⋯ and ⋯BBB⋯) chains along the b axis. These chains are inter­connected by further heteromolecular C—H⋯O inter­actions

1-Methyl­piperazine-1,4-diium dipicrate

In the crystal structure of the title compound [systematic name: 1-methyl­piperazine-1,4-diium bis­(2,4,6-trinitro­phen­ol­ate)], C5H14N2 2+·2C6H2N3O7 −, the ionic components are connected by relatively strong N—H⋯O hydrogen bonds into centrosymmetric six-membered conglomerates, which comprise two dications and four anions. Besides Coulombic inter­actions, only weak C—H⋯O inter­actions and some stacking between picrates (separation between the planes of ca. 3.4 Å but only a small overlapping) can be identified between these ‘building blocks’ of the crystal structure. The piperazine ring adopts a chair conformation with the methyl substituent in the equatorial position. In the picrate anions, the twist angles of the nitro groups depend on their positions relative to the phenolate O atom: it is much smaller for the NO2 groups para to the C—O− group [15.23 (9)and 3.92 (14)°] than for the groups in the ortho positions [28.76 (13)–39.84 (11)°]

On the efficacy of a novel optimized tuned mass damper for minimizing dynamic responses of cantilever beams

This study examines the optimal design of a tuned mass damper (TMD) in the frequency domain so that the dynamic response of cantilever beams can be decreased. Random vibration theory is applied to identify the mean square acceleration of the endpoint of a cantilever beam as the objective function to be reduced. In addition, to determine the optimal TMD coefficient of mass, stiffness, and damping, a differential evolution (DE) optimization algorithm is employed. The upper and lower limit values of these parameters are taken into account. A majority of the previous studies have concentrated on determining just the stiffness and damping parameters of TMD. Nonetheless, in this study there is also the optimization of TMD mass parameters to determine the mass quantity. In addition, there has been inefficient use of the stochastic DE optimization algorithm method for the optimization of TMD parameters in previous studies. Hence, to obtain optimal TMD parameters, this algorithm is precisely used on the objective function. Tests are carried out on the cantilever beam with the TMD system following this optimization method with harmonic base excitations that resonate the foremost modes of the beam and white noise excitation. The method proposed here is reasonably practical and successful regarding the optimal TMD design. When a TMD is designed appropriately, the response of the cantilever beam under dynamic interactions undergoes a considerable reduction