• Journal of Advanced Marine Engineering and Technology
• /
• v.20 no.4
• /
• pp.50-58
• /
• 1996

The torsional vibration of the propulsion shafting system equipped with viscous damper is investigated. The equivalent system is modeled by a two mass softening system with Duffing's oscillator and the vibratory motion is described by non-linear differential equations of second order. The damper casing is fixed at the front-end of crankshaft and the damper's inertia ring floats in viscous silicon fluid inside of the camper casing. The excitation frenquency is proportional to the rotational speed of engine. The steady state response of the equivalent system is analyzed by the computer and for this analyzing, the harmonic balance method is adopted as a non-linear vibration analysis technique. Frequency response curves are obtained for 1st order resonance only. Jump phenomena are explained. The discriminant for the solutions of the steady state response is derived. Both theoretical and measured results of the propulsion shafting system are compared with and evaluated. As a result of comparisions with both data, it was confirmed that Duffing's oscillator can be used in the modeling of the propulsion shafting system attached with viscous damper with non-linear stiffness.

• Journal of Advanced Marine Engineering and Technology
• /
• v.20 no.4
• /
• pp.372-372
• /
• 1996

The torsional vibration of the propulsion shafting system equipped with viscous damper is investigated. The equivalent system is modeled by a two mass softening system with Duffing's oscillator and the vibratory motion is described by non-linear differential equations of second order. The damper casing is fixed at the front-end of crankshaft and the damper's inertia ring floats in viscous silicon fluid inside of the camper casing. The excitation frenquency is proportional to the rotational speed of engine. The steady state response of the equivalent system is analyzed by the computer and for this analyzing, the harmonic balance method is adopted as a non-linear vibration analysis technique. Frequency response curves are obtained for 1st order resonance only. Jump phenomena are explained. The discriminant for the solutions of the steady state response is derived. Both theoretical and measured results of the propulsion shafting system are compared with and evaluated. As a result of comparisions with both data, it was confirmed that Duffing's oscillator can be used in the modeling of the propulsion shafting system attached with viscous damper with non-linear stiffness.

• Structural Engineering and Mechanics
• /
• v.41 no.1
• /
• pp.1-24
• /
• 2012

A reinforced concrete (RC) framed structure detailed according to non-seismic detailing provisions as per Indian Standard was tested on shake table under dynamic loads. The structure had 3 main storeys and an additional storey to simulate the footing to plinth level. In plan the structure was symmetric with 2 bays in each direction. In order to optimize the information obtained from the tests, tests were planned in three different stages. In the first stage, tests were done with masonry infill panels in one direction to obtain information on the stiffness increase due to addition of infill panels. In second stage, the infills were removed and tests were conducted on the structure without and with tuned liquid dampers (TLD) on the roof of the structure to investigate the effect of TLD on seismic response of the structure. In the third stage, tests were conducted on bare frame structure under biaxial time histories with gradually increasing peak ground acceleration (PGA) till failure. The simulated earthquakes represented low, moderate and severe seismic ground motions. The effects of masonry infill panels on dynamic characteristics of the structure, effectiveness of TLD in reducing the seismic response of structure and the failure patterns of non-seismically detailed structures, are clearly brought out. Details of design and similitude are also discussed.

• Smart Structures and Systems
• /
• v.20 no.6
• /
• pp.669-682
• /
• 2017

The normalised version of bispectrum, the so-called bicoherence, has often proved a reliable method of damage detection on engineering applications. Indeed, higher-order spectral analysis (HOSA) has the advantage of being able to detect non-linearity in the structural dynamic response while being insensitive to ambient vibrations. Skewness in the response may be easily spotted and related to damage conditions, as the majority of common faults and cracks shows bilinear effects. The present study tries to extend the application of HOSA to damage localisation, resorting to a neural network based classification algorithm. In order to validate the approach, a non-linear finite element model of a 4-meters-long cantilever beam has been built. This model could be seen as a first generic concept of more complex structural systems, such as aircraft wings, wind turbine blades, etc. The main aim of the study is to train a Neural Network (NN) able to classify different damage locations, when fed with bispectra. These are computed using the dynamic response of the FE nonlinear model to random noise excitation.

• Journal of the Architectural Institute of Korea Structure & Construction
• /
• v.35 no.11
• /
• pp.129-136
• /
• 2019

Non-structural elements are vulnerable to earthquake ground motion. In this study, an experimental study for the electrical non-structural element was performed using tri-axial shaking table tests. A 100kVA UPS(Uninterruptible Power Supply system) was used as the test specimen. The test specimen was anchored to the concrete slab using the conventional installation detail. The input acceleration were generated in accordance with ICC-ES AC156 code. Scale factors of the input acceleration with respect to the required response spectrum defined in ICC-ES AC156 were from 25% to 600%. Based on the test results, damage and dynamic characteristics of UPS were evaluated and analyzed including natural frequency, damping ratio, acceleration time history response, dynamic amplification factor and relative displacement.

• Journal of Sericultural and Entomological Science
• /
• v.36 no.2
• /
• pp.115-118
• /
• 1994

Differences of feeding response of 280 silkworm genetic stocks and 71 breeding lines to MP-O artificial diet and the mode of the inheritance were investigated. Feeding response to MP-O diet varied markedly between the silkworm varieties, and the non-normally distributed curve for the response was observed. From the genetic analysis, the high feeding response to MP-O diet was recessive to the low feeding response. Therefore it is considered that the high feeding response of the newly hatched silkwrom larvae to MP-O diet is controlled by a recessive gene.

• Korean Journal of Biological Psychiatry
• /
• v.24 no.4
• /
• pp.188-195
• /
• 2017

Objectives Schizophrenia is characterized by disturbances in perception and cognition. Attenuated mismatch negativity (MMN) reflects central auditory dysfunction in schizophrenia. The aim of this study is to compare MMN changes before and after treatment in schizophrenia patients and to assess their association with treatment response. Methods Twenty-three schizophrenia patients underwent an oddball paradigm. MMN was calculated by the difference waveforms of the event-related potentials (ERPs) elicited by subtracting standard from deviant stimulus. The clinical symptoms were measured by the Positive and Negative Syndrome Scale (PANSS), the Psychotic Symptom Rating Scale (PSYRATS). Follow-up evaluation was conducted when the PANSS total score decreased by 30% or more (treatment response group) or before discharge (non-response group). Results The treatment response group showed significantly larger MMN amplitude improvement and latency reduction than the non-response group after treatment (Fz ; mean amplitude p = 0.035, FCz ; p = 0.041). The auditory hallucination group showed shorter latency than that of the group without hallucinations. Additionally, auditory hallucination was associated with prolonged MMN latency and shortened after treatment in the auditory hallucination response group (Fz ; p = 0.048). Conclusions These results suggest that the attenuated MMN amplitude reflects the progression of the disease. The increment of MMN amplitude and shortening of latency after treatment may reflect cognitive functional recovery of central auditory sensory processing.

• Advances in aircraft and spacecraft science
• /
• v.7 no.5
• /
• pp.405-423
• /
• 2020

Non-linear energy sink (NES) is an emerging passive absorber able to mitigate the dynamic response of structures without any external energy supply, resonating with all the modes of the primary structure to control. However, its inherent non-linearities hinder its large-scale use and leads to complicated design procedures. For this purpose, an approximate design approach is herein proposed in a stochastic framework. Since loads are random in nature, the stochastic analysis of non-linear systems may be performed by means of computational intensive techniques such as Monte Carlo simulations (MCS). Alternatively, the Stochastic Linearisation (SL) technique has proven to be an effective tool to investigate the performance of different passive control systems under random loads. Since controlled systems are generally non-classically damped and most of SL algorithms operate recursively, the computational burden required is still large for those problems that make intensive use of SL technique, as optimal design procedures. Herein, a procedure to speed up the Stochastic Linearisation technique is proposed by avoiding or strongly reducing numerical evaluations of response statistics. The ability of the proposed procedure to effectively reduce the computational effort and to reliably design the NES is showed through an application on a well-known case study related to the vibrations mitigation of an aircraft wing.

• International Journal of Internet, Broadcasting and Communication
• /
• v.12 no.1
• /
• pp.81-89
• /
• 2020

The purpose of this study is to investigation the effects of functional compression clothing on muscle function by comparing the iEMG response of muscle during exercise according to the wearing of taping applied functional clothing. Six men in their twenties in Chungcheongnam-do were selected for the study. Resistance exercise was performed by cross-distributing the conditions of wearing and not wearing functional clothing. Resistance exercises for iEMG measurements are biceps curl, wrist curl, reverse wrist curl, kickback and push-up. iEMG measurement muscles were the biceps brachii, triceps brachii, extensor carpi ulnaris, flexor carpi radialis. During biceps curl exercise, the iEMG of triceps brachii, biceps brachii wearing condition was lower than the non-wearing condition. During kickback exercise, the iEMG of triceps brachii, extensor carpi ulnaris wearing condition was lower than the non-wearing condition. During reverse wrist curl exercise, the iEMG of extensor carpi ulnaris wearing condition was lower than the non-wearing condition. During wrist curl exercise, the iEMG of flexsor biceps brachii, carpi radialis wearing condition was lower than the non-wearing condition. During push-up exercise, the iEMG of triceps flexsor biceps brachii, carpi radialis, brachii, biceps brachii non-wearing condition was lower than the wearing condition.

• Earthquakes and Structures
• /
• v.4 no.3
• /
• pp.241-264
• /
• 2013

Since the beginning of the twentieth century, the progressive and rapid spread of reinforced concrete (RC) has led to the adoption of mixed masonry-RC solutions, such as the confined masonry. However, together with structures conceived with a definite role for earthquake behaviour, the spreading of RC technology has caused the birth of mixed solutions inspired more by functional aspects than by structural ones, such as: internal masonry walls replaced by RC frames, RC walls inserted to build staircases or raising made from RC frames. Usually, since these interventions rise from a spontaneous build-up, any capacity design or ductility concepts are neglected being designed only to bear vertical loads: thus, the vulnerability assessment of this class becomes crucial. To investigate the non-linear seismic response of these structures, suitable models and effective numerical tools are needed. Among the various modelling approaches proposed in the literature and codes, the authors focus their attention on the equivalent frame model. After a brief description of the adopted model and its numerical validation, the authors aim to point out some specific peculiarities of the seismic response of mixed masonry-RC structures and their repercussions on safety verification procedures (referring in particular way to the non-linear static ones). In particular, the results of non-linear static analyses performed parametrically to various configurations representative of different interventions are discussed.