Experimental Analysis to Evaluate the Effect of Dynamic Absorber / M. Azhan Anuar...[et al.]

Passive Dynamic Absorber (PDA) is a mechanical device used to tackle unwanted vibration resonance within the operational frequency of the system. Theoretically, resonance can be avoided if the excitation (operating) frequency is far away from the natural frequencies of the structures. Hence, it is important to identify the structural natural frequencies, to ensure this condition did not occur. In this study, an experimental main system is designed and fabricated and then, tested using Operational Modal Analysis (OMA) to obtain the natural frequency. PDAs are developed based on Dunkley Method (DM) and Randy Fox Method (RFM) and applied to the main vibrating system. Frequency Response Function (FRF) for both models is obtained using OMA and its effectiveness is evaluated. It is shown that the PDA reduces the magnitude of FRF of the main system at the selected resonance frequency and splitting it into two new resonance frequencies. Hence, it can be predicted that the vibration can be effectively suppressed at a specific frequency when the PDA is attached to the main system. This study enables verification of the effectiveness of dynamic absorber to tackle resonance problem. In future, these results will be helpful to evaluate the performance of PDA based on DM and RFM methods

Performance Evaluation of Dynamic Absorbers Based on Randy Fox and Dunkerley Methods / Syafirah A. Samat ...[et al.]

Dynamic Absorber (DA) application is the method used to avoid resonance in a vibrating system. In practice, many types of DA are utilized such as active and passive DA and it depends on the cost and environmental conditions. Designers/ engineers select DA parameters and model the absorber before it is implemented and tested to the main system. Hence, it will be beneficial to have tools or templates for fast and effective selection of DA. This paper will discuss the selection parameters of a passive DA based on templates derived from Dunkerley Method (DM) and Randy Fox Method (RFM) and its accuracy is verified experimentally. It is observed that in this case, DA has reduced the vibration amplitude significantly. Furthermore, the results show the RFM absorber has performed better than the DM absorber. This study enables verification of the effectiveness of DA to tackle resonant problems. In the future, these GUI templates could be helpful for industrial application with vibrating problems

An investigation of the dynamic characteristics of a bolted-rotor system

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Development of a real-time-position prediction algorithm for under-actuated robot manipulator by using of artificial neural network

An adaptive learning algorithm using an artificial neural network (ANN) has been proposed to predict the passive joint position of under-actuated robot manipulator. In this approach, a specific ANN model has been designed and trained to learn a desired set of joint angular positions for the passive joint from a given set of input torque and angular position for the active joint over a certain period of time. Trying to overcome the disadvantages of many used techniques in the literature, the ANNs have a significant advantage of being a model-free method. The learning algorithm can directly determine the position of its passive joint, and can, therefore, completely eliminate the need for any system modelling. Even though it is very difficult in practice, data used in this study were recorded experimentally from sensors fixed on robot's joints to overcome the effect of kinematics uncertainties present in the real world such as ill-defined linkage parameters and backlashes in gear trains. An ANN was trained using the experimentally obtained data and then used to predict the path of the passive joint that is positioned by the dynamic coupling of the active joint. The generality and efficiency of the proposed algorithm are demonstrated through simulations of an under-actuated robot manipulator; finally, the obtained results were successfully verified experimentally. © Authors 2011

International Nosocomial Infection Control Consortium report, data summary of 50 countries for 2010-2015: Device-associated module

•We report INICC device-associated module data of 50 countries from 2010-2015.•We collected prospective data from 861,284 patients in 703 ICUs for 3,506,562 days.•DA-HAI rates and bacterial resistance were higher in the INICC ICUs than in CDC-NHSN's.•Device utilization ratio in the INICC ICUs was similar to CDC-NHSN's. Background: We report the results of International Nosocomial Infection Control Consortium (INICC) surveillance study from January 2010-December 2015 in 703 intensive care units (ICUs) in Latin America, Europe, Eastern Mediterranean, Southeast Asia, and Western Pacific. Methods: During the 6-year study period, using Centers for Disease Control and Prevention National Healthcare Safety Network (CDC-NHSN) definitions for device-associated health care-associated infection (DA-HAI), we collected prospective data from 861,284 patients hospitalized in INICC hospital ICUs for an aggregate of 3,506,562 days. Results: Although device use in INICC ICUs was similar to that reported from CDC-NHSN ICUs, DA-HAI rates were higher in the INICC ICUs: in the INICC medical-surgical ICUs, the pooled rate of central line-associated bloodstream infection, 4.1 per 1,000 central line-days, was nearly 5-fold higher than the 0.8 per 1,000 central line-days reported from comparable US ICUs, the overall rate of ventilator-associated pneumonia was also higher, 13.1 versus 0.9 per 1,000 ventilator-days, as was the rate of catheter-associated urinary tract infection, 5.07 versus 1.7 per 1,000 catheter-days. From blood cultures samples, frequencies of resistance of Pseudomonas isolates to amikacin (29.87% vs 10%) and to imipenem (44.3% vs 26.1%), and of Klebsiella pneumoniae isolates to ceftazidime (73.2% vs 28.8%) and to imipenem (43.27% vs 12.8%) were also higher in the INICC ICUs compared with CDC-NHSN ICUs. Conclusions: Although DA-HAIs in INICC ICU patients continue to be higher than the rates reported in CDC-NSHN ICUs representing the developed world, we have observed a significant trend toward the reduction of DA-HAI rates in INICC ICUs as shown in each international report. It is INICC's main goal to continue facilitating education, training, and basic and cost-effective tools and resources, such as standardized forms and an online platform, to tackle this problem effectively and systematically