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Review of complex adaptive systems in nursing practice
Get PDFThis article describes the most typical characteristics of complex adaptive systems (CAS) theory and how it works in healthcare organizations and nursing practice. Complexity science belongs to newest systems thinking, which explore complex systems by focusing on the system components, relationships and interconnections rather than on the individual components themselves. The nurse must therefore always keep in mind the larger picture when caring for the individual patient and expect to be disturbed by unexpected possibilities. The incorporation of complexity science concepts into the practice of nursing leadership encourages new ways of thinking about organizations and is a natural model for the ideals and expected results of skilled nursing. CAS theory will take a permanent place in the healthcare organizations activities, improve nursing processes and create a better work environment for nursing and job satisfaction
Linear forced-rotordynamics analysis for optimizing the performance factors of machine motorized spindle using design explorer method
Get PDFA machine-tool structure optimization is an important technique that improves the machining efficiency and saves materials and the energy resource. In this work, dynamic design optimization method for Machine-Motorized-Spindle (MMS) subjected to a number of rotating unbalanced forces effects is presented. Linear forced-Rotordynamic analysis with design explorer method has been used to simulate the output response. The Design Variables (DVs) and their limits were carefully chosen and applied to develop the Design-of-Experiment (DOE). The Box-Behnken Design (BBD) method, because of its good organization in providing much information in a minor number of required statistical experiments was used to generate the DOE. The influences of DVs on the dynamic of MMS and their levels optimization were evaluated by utilizing the Response-Surface (RS) method. The results showed that the spindle shaft inner diameter of the motor-rotor seat and its rotating unbalanced mass, and modulus of elasticity have the highest contribution in effect on the dynamic of MMHS. As well, it is found that the proposed optimization method not only improves the structural weight of MMS, but also the potential saving can be achieved in term material and energy resource
Research on cold mechanical vibration of air-cooled disc brake
Get PDFCold mechanical vibration of air-cooled brake disc is mainly caused by the non-uniform geometry, including disk thickness variation (DTV) and side face run-out (SFR). A mathematical model consisting of the non-uniform geometry is constructed, which is imported into the dynamic brake model established by Lagrange equation as initial parameters. The braking moment fluctuation during braking process is obtained by MATLAB software. The experimental verification is realized based on Link3900 NVH test platform, where result shows that the calculated brake pressure is quite consistent with the test value. By single variable method, the key influence factor that affected braking moment fluctuation is analyzed, including DTV, SFR, friction coefficient, contact stiffness coefficient and damping coefficient. The conclusion shows that reducing these parameters within a certain range can significantly reduce the amplitude of cold vibration, except for the contact damping coefficient
Vibration suppression effects on rotating wind turbine blade using a particle damping method
Get PDFDue to the vibration of the wind turbine blade, the rate of electricity generation gets reduced. In this research, the focus is on reduction of wind turbine blade vibration. The important point is that in the attempt of vibration suppression, a new method of damping named particle damping has been tried. The novelty of this study is that this method is adopted for the first time in wind turbine blade for rotating condition. In this method, containers filled with spherical particles are mounted at four different positions on each blade alternatively. Taking tests at different rpm and container positions gives a different vibration suppression effect as compared to without damping and finding optimum positions for mounting of damper
Effect of slant angle variation on the drag force for Ahmed body car model
Get PDFIn this paper, numerical investigation is carried out on two-dimensional Ahmed body model using Computational Fluid Dynamics in ANSYS Fluent 19.1. The 2-D model is designed in Catia v5 for 25°, 35° and 45° slant angles. The turbulent model used to analyze the flow dynamics is Realizable k-ε model. The drag coefficient variation with respect to slant angle is computed. The skin friction coefficient, wall shear stress and frictional velocity are also calculated
Measurement of damping properties of beeswax and cosmetic wax using Oberst beam method
Get PDFDamping treatment is a standard practice in many industries for controlling excessive vibration at resonance. Different damping materials are available for various engineering applications. Wax is one of them, and it’s mostly used in musical instruments. There are two types of wax are available namely beeswax (natural wax) and cosmetic wax. The aim of the present study is to measure damping properties of these two types of wax using Oberst Beam Method (OBM). The effects of damping material’s thickness and bare sample on damping loss factor are studied
A method based on multiscale base-scale entropy and random forests for roller bearings faults diagnosis
Get PDFA method based on multiscale base-scale entropy (MBSE) and random forests (RF) for roller bearings faults diagnosis is presented in this study. Firstly, the roller bearings vibration signals were decomposed into base-scale entropy (BSE), sample entropy (SE) and permutation entropy (PE) values by using MBSE, multiscale sample entropy (MSE) and multiscale permutation entropy (MPE) under different scales. Then the computation time of the MBSE/MSE/MPE methods were compared. Secondly, the entropy values of BSE, SE, and PE under different scales were regarded as the input of RF and SVM optimized by particle swarm ion (PSO) and genetic algorithm (GA) algorithms for fulfilling the fault identification, and the classification accuracy was utilized to verify the effect of the MBSE/MSE/MPE methods by using RF/PSO/GA-SVM models. Finally, the experiment result shows that the computational efficiency and classification accuracy of MBSE method are superior to MSE and MPE with RF and SVM
Bearing failure prediction using Wigner-Ville distribution, modified Poincare mapping and fast Fourier transform
Get PDFThis study outlines the experimental investigation methods of condition monitoring to predict bearing failures using the experimental vibration signatures. The purpose of condition monitoring is to maximize the machine availability and utility of the machine components. Bearings being one of the most common component in any rotating machinery, it is vital to study the health of the bearing and can predict bearing failure, its location and severity. This prevents machine downtime, monetary loss and unfortunate accidents. A test rig was fabricated to get the vibration signatures of bearings. Prediction of bearing failure relies on the presence of the bearing characteristic frequencies – inner race frequency, outer race frequency, ball pass frequency and fundamental train frequency – and its harmonics in the vibration signal acquired. These frequencies are present in the vibration signature due to the interaction of surfaces of different bearing components that have defects in them. Both time and frequency domain numerical signature analysis were performed on the vibration signatures acquired. Simple frequency domain method like Fast Fourier Transform (FFT), chaotic vibration method like modified Poincare mapping and time-frequency domain Wigner-Ville distribution (WVD) were used in detecting bearing failure. Using the FFT analysis method, it is hard to predict the failures, hence better signal processing methods like modified Poincare mapping and WVD are used. Also, it is observed that the chaotic vibration signatures found in the lower-order mechanical systems like bearings. With the chaotic analysis methods like, Poincare Mapping and Wigner-Ville Distribution, the location and the severity of the bearing failure can be predicted
Cogging force reduction for tubular permanent magnet linear motor by slots with different sizes
Get PDFReduction of cogging force is one of the main concerns of tubular permanent magnet linear motor (TPMLM). In this paper, an analytical calculation of air-gap magnetic density is derived. In addition, an analytical calculation of cogging force is deduced by the energy method. The impact of slots with different sizes on the Fourier coefficients of relative air-gap permanence function is demonstrated. When the nz/4p is the integer, it will produce the cogging force. Therefore, it is practical to reduce the cogging force by changing the Fourier coefficient smaller. The effectiveness of the theoretical analysis is validated by experimental results
The semi-analytical method for damping of tubular transition layer damping structure
Get PDFTo solve the limited vibration consumption of the traditional tubular damping structure (TTDS), the tubular transition layer damping structure (TTLDS) is proposed; Based on viscoelastic materials and theories of thin cylindrical shells, the governing equation, the first order matrix differential equation describing vibration of TTLDS under harmonic excitation, is derived by considering the interaction between all layers and the dissipation caused by the shear deformation for transition layer and damping layer. By using the extended homogeneous capacity precision integration method to solve the control equation, a semi-analytical method for studying the vibration and damping characteristics of TTLDS is given. By way of comparison, the correctness of the method provided in paper is verified. At last, the influence of thickness, material and location of transition layer on damping effect is analyzed. The results show that the change for the thickness or material of the transition layer can make the structural damping effect change greatly, while the change for location of the transition layer plays only a few roles on the structural damping effect