Marginally outer trapped surfaces in the Schwarzschild spacetime: Multiple self-intersections and extreme mass ratio mergers

Tuned mass dampers (TMD) are one of the most reliable devices to control the vibration of the structure. The optimum mass ratio required for a single tuned mass damper (STMD) is evaluated corresponding to the fundamental natural frequency of the structure. The effect of STMD and Multiple tuned mass dampers (MTMD) on a G+20 storey structure are studied to demonstrate the damper’s effectiveness in seismic application. The location and number of tuned mass dampers are studied to give best structural performance in maximum reduction of seismic response for El Centro earthquake data. The analysis results from SAP 2000 software tool shows damper weighing 2.5% of the total weight of the structure effectively reduce the response of the structure. Study shows that introduction of 4-MTMD at top storey can effectively reduce the response by 10% more in comparison to single tuned mass damper. The use of MTMD of same mass ratio that of STMD is more effective in seismic response.

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Chitosan-based Magnetic Composites - Efficient Adsorbents for Removal of Pb(II) and Cu(II) from Aqueous Mono and Bicomponent Solutions

Revista de Chimie ◽

10.37358/rc.18.9.6527 ◽

2018 ◽

Vol 69 (9) ◽

pp. 2323-2330 ◽

Cited By ~ 1

Author(s):

Daniela C. Culita ◽

Claudia Maria Simonescu ◽

Rodica Elena Patescu ◽

Nicolae Stanica

Keyword(s):

Aqueous Solutions ◽

Metal Ions ◽

Chemical Properties ◽

Order Kinetic ◽

Mass Ratio ◽

Magnetic Adsorbent ◽

Magnetic Composites ◽

Initial Ph ◽

Order Kinetic Model ◽

Physical And Chemical

A series of three chitosan-based magnetic composites was prepared through a simple coprecipitation method. It was investigated the influence of mass ratio between chitosan and magnetite on the physical and chemical properties of the composites in order to establish the optimum conditions for obtaining a composite with good adsorption capacity for Pb(II) and Cu(II) from mono and bicomponent aqueous solutions. It was found that the microspheres prepared using mass ratio chitosan / magnetite 1.25/1, having a saturation magnetization of 15 emu g--1, are the best to be used as adsorbent for the metal ions. The influence of different parameters such as initial pH values, contact time, initial concentration of metal ions, on the adsorption of Pb(II) and Cu(II) onto the chitosan-based magnetic adsorbent was investigated in details. The adsorption process fits the pseudo-second-order kinetic model in both mono and bicomponent systems, and the maximum adsorption capacities calculated on the basis of the Langmuir model were 79.4 mg g--1 for Pb(II) and 48.5 mg g--1 for Cu(II) in monocomponent systems, while in bicomponent systems were 88.3 and 49.5 mg g--1, respectively. The results revealed that the as prepared chitosan-based magnetic adsorbent can be an effective and promising adsorbent for Pb(II) and Cu(II) from mono and bicomponent aqueous solutions.

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ACCURACY RATING MEASUREMENT OF VIBRATION ELECTROMECHANICAL DEVICES

Issues of radio electronics ◽

10.21778/2218-5453-2019-7-42-45 ◽

2019 ◽

Vol 1 (7) ◽

pp. 42-45

Author(s):

V. A. Golubkov ◽

V. F. Shishlakov ◽

A. G. Fedorenko ◽

E. Yu. Vataeva

Keyword(s):

Technical Condition ◽

Rotor System ◽

Vibration Measurement ◽

Random Errors ◽

Mass Ratio ◽

Signal Flow Graph ◽

Bond Graphs ◽

Rotor Systems ◽

Electromechanical Devices ◽

Main Components

Electromechanical devices consist mainly of rotor systems. Vibration is the result of the interaction of the elements of the rotor system and is largely determined by the accuracy of manufacturing elements at the production stage and defects arising in the process of operation. The main components of the rotor systems that affect vibration are bearings. To determine the technical condition of the bearings and the service life of the rotor system, it is necessary to accurately measure the unobservable vibrations of the rotor. The article describes the model of the channel for measuring the vibration of an electromechanical system, built using the apparatus of bond graphs. The transfer function is obtained by analyzing the signal flow graph. The systematic and random errors of vibration measurement are analyzed depending on the mass ratio between the system case and the vibration transducer for various sensor masses and attachment rigidity.

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Pyrolysis of unsubstituted bicyclic hydrocarbons and gas oil

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19821838 ◽

1982 ◽

Vol 47 (7) ◽

pp. 1838-1847 ◽

Cited By ~ 6

Author(s):

Martin Bajus ◽

Jozef Baxa

Keyword(s):

Stainless Steel ◽

Elemental Sulphur ◽

Raw Material ◽

Gas Oil ◽

Mass Ratio ◽

Reaction Products ◽

Pyrolysis Products ◽

Reactor Material ◽

Tubular Reactors ◽

Stainless Steel Reactor

Pyrolysis of tetraline, decaline, 1,1'-bicyclohexane, cyclohexylbenzene and gas oil was studied in stainless steel and quartz flow tubular reactors at 780 and 800 °C, residence time 0.08 to 0.5 s and at the mass ratio of steam to the raw material changing from 0.5 to 1.5. The effect of reaction temperature, the mass ratio of steam to the raw material, reactor material and of the added elemental sulphur on the yields of individual reaction products is reported. Of bicyclic hydrocarbons, condensed hydrocarbons are more stable than those with noncondensed rings, cyclanoaromates being more stable than bicyclanes. Pyrolysis of gas oil in the stainless steel reactor yields greater amounts of ethylene, propylene, butadiene and smaller amounts of methane and ethane, compared to the pyrolysis carried out under identical conditions in the quartz reactor. Elemental sulphur increases the conversion of gas oil into gaseous pyrolysis products.

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Galaxy Formation: Some Comparisons between Theory and Observation

Symposium - International Astronomical Union ◽

10.1017/s0074180900033350 ◽

1983 ◽

Vol 100 ◽

pp. 391-399 ◽

Cited By ~ 1

Author(s):

S. Michael Fall

Keyword(s):

Galaxy Formation ◽

Total Mass ◽

Virial Theorem ◽

Velocity Dispersion ◽

Rotation Velocity ◽

Morphological Type ◽

Fundamental Parameter ◽

Mass Ratio ◽

First Approximation ◽

Type Form

Before theoretical ideas in this subject can be compared with observational data, it is necessary to consider the properties of galaxies that are likely to be relics of their formation. Most astronomers would agree that the list of important parameters should be headed by the total mass M, energy E and angular momentum J. Next on the list should probably be the relative contributions to these quantities from the disc and bulge components of galaxies and denoted D/B for the mass ratio. They can be estimated from the median (i.e. half-mass) radius R, velocity dispersion σ and rotation velocity v of each component, either through the virial theorem or through the luminosity L and an assumed value of M/L. As a first approximation, it is reasonable to suppose that galaxies of a given disc-to-bulge ratio or morphological type form a sequence with mass as the fundamental parameter. The comparison of theory with data is further simplified by considering the extreme cases of ellipticals, with D/B << 1, and late-type spirals, with D/B >> 1. The approach outlined below is to explore the consequences of relaxing in succession the constraints that E, J and M be conserved during the collapse of proto-galaxies. In this article I concentrate on theories that are based on some form of hierarchical clustering because the pancake and related theories are not yet refined enough for a detailed confrontation with observations.

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