Study of synchronization for a rotor-pendulum system with Poincare method

A simplified model of the system of unbalanced rotors coupled with pendulum rod is examined. The model consists of two counter-rotating rotors, a rigid pendulum rod and a rigid vibrating body, which is horizontally connected to a fixed support by means of springs. The synchronous state of the system, i.e. synphase and antiphase synchronization of the rotors, is studied by means of the Poincare method. Moreover, the assessment of the synchronous state is converted to find a solution that should satisfy a balanced function and a stability function of the system. However, frequency ratios and installation angular are included in the two functions. It is demonstrated that the spring stiffness and the installation angular have a large influence on the existence and stability of the synchronization state in the coupling system. Finally, computer simulations are preformed to verify the theoretical computations

Synchronization of the secondary isolation system with a dual-motor excitation

A dynamical model is proposed in this paper to study the synchronization and stability of the secondary isolation system with a dual-motor excitation. After deducing the dynamic equations of the system by Lagrange’s equation, the Laplace transform is used to deduce the displacement responses of the system when the system operate in steady state. The synchronous balance equation and stability condition of the system is derived with average method, and the relationship between the coefficient of synchronous ability and the geometric parameters of the system is discussed. It can be found that synchronization ability of the system is gradually increased with the increase between two motors mounting distance; meanwhile the larger difference of the mass between the two unbalanced rotors, the more difficult to implement synchronous operation of the system. Moreover, the stable phase difference of the vibrating system being as the key determinant to reach synchronization is discussed numerically. The research result shows that the synchronous behavior of the system is influenced by rotation direction of the rotors, mounting position of two motors, and mass ratios between unbalanced rotors and vibrating body. The correctness of theoretical analyses is verified by simulation results with Runge-Kutta method

Theoretical study on self-synchronization of two homodromy rotors coupled with a pendulum rod in a far-resonant vibrating system

The objective of this paper is to investigate the self-synchronization of two homodromy rotors coupled with a pendulum rod in a far-resonant vibrating system. Using the average method and revisionary small parameters, we derive the dimensionless equation of the self-synchronization criterion and synchronous stability of the vibrating system. Meanwhile, to prove the correctness of the theoretical analysis, the diversity feature of the vibrating system is simulated numerically. Both results of theoretical analysis and numerical simulation show that increasing the length of the pendulum rod or decreasing the mass of the rotor connected with pendulum rod can ensure the self-synchronization and synchronous stability of two homodromy rotors in the vibrating system

Selection of waterlogging-tolerant and water purification herbaceous plants for the construction of a sponge city in Shenzhen, China

In recent years, seeking solutions to urban waterlogging and water pollution has always been one of the topics of concern. The problem of urban water accumulation occurs frequently in most areas of China in July and August. The contradiction between supply and demand of urban ecological water is prominent. In order to solve the problem of urban water accumulation caused by rainfall concentration, and to achieve the overall goal of building a water-saving green ecological city, the Shenzhen City should be built into a sponge city. Under this background, the physiological response of different forages to waterlogging stress and the removal of pollutants in rainwater were studied. In this study, ten herbaceous plants commonly used in Shenzhen were used as experimental materials. After 0, 7, 14, 21, 28 days of waterlogging stress treatment, six physiological indexes, such as MDA, SP, and Pro contents and SOD, POD, and CAT activities, were comprehensively evaluated. Combined with the morphological changes of the plants after waterlogging, seven plants with strong waterlogging tolerance were determined, which were O. bodinieri, H. coronarium, I. tectorum, D. ensifolia, R. brittoniana, C. indica, and A. zerumbet. Then, according to their comprehensive evaluation of the removal capacity of pollutants in the rainwater, it is suggested to select O. bodinieri, H. coronarium, I. tectorum and D. ensifolia in areas with serious waterlogging. In areas with serious water pollution, R. brittoniana, A. zerumbet, D. ensifolia and H. coronarium are recommended. However, H. coronarium and D. ensifolia not only have a strong adaptability in the waterlogged environment, but also have a strong ability to remove pollutants in the rainwater, so they are suggested to be alternative herbaceous plants for sponge city in Shenzhen, China

Synchronization and Stability of Two Unbalanced Rotors with Fast Antirotation considering Energy Balance

We consider synchronization and stability of two unbalanced rotors reversely and fast excited by induction motors fixed on an oscillating body. We explore the energy balance of the system and show how the energy is transferred between the rotors via the oscillating body allowing the implementation of the synchronization of the two rotors. An approximate analytical analysis, energy balance method, allows deriving the synchronization condition, and the stability criterion of the synchronization is deduce by disturbance differential equations. Later, to prove the correctness of the theoretical analysis, many features of the vibrating system are computed and discussed by computer simulations. The proposed method may be useful for analyzing and understanding the mechanism of synchronization, stability, and energy balance of similar fast rotation rotors excited by induction motors in vibrating systems

Synchronization of the secondary isolation system with a dual-motor excitation

A dynamical model is proposed in this paper to study the synchronization and stability of the secondary isolation system with a dual-motor excitation. After deducing the dynamic equations of the system by Lagrange’s equation, the Laplace transform is used to deduce the displacement responses of the system when the system operate in steady state. The synchronous balance equation and stability condition of the system is derived with average method, and the relationship between the coefficient of synchronous ability and the geometric parameters of the system is discussed. It can be found that synchronization ability of the system is gradually increased with the increase between two motors mounting distance; meanwhile the larger difference of the mass between the two unbalanced rotors, the more difficult to implement synchronous operation of the system. Moreover, the stable phase difference of the vibrating system being as the key determinant to reach synchronization is discussed numerically. The research result shows that the synchronous behavior of the system is influenced by rotation direction of the rotors, mounting position of two motors, and mass ratios between unbalanced rotors and vibrating body. The correctness of theoretical analyses is verified by simulation results with Runge-Kutta method

Time Course for Benefit and Risk of Ticagrelor and Aspirin in Acute Ischemic Stroke or Transient Ischemic Attack

Aspirin; Acute Ischemic Stroke, BenefitAspirina; Accidente cerebrovascular isquémico agudo; BeneficioAspirina; Accident cerebrovascular isquèmic agut; BeneficiBackground and objectives: The goal of this work was to investigate the short-term time-course benefit and risk of ticagrelor with aspirin in acute mild-moderate ischemic stroke or high-risk TIA in The Acute Stroke or Transient Ischemic Attack Treated with Ticagrelor and ASA for Prevention of Stroke and Death (THALES) trial. Methods: In an exploratory analysis of the THALES trial, we evaluated the cumulative incidence of irreversible efficacy and safety outcomes at different time points during the 30-day treatment period. The efficacy outcome was major ischemic events defined as a composite of ischemic stroke or nonhemorrhagic death. The safety outcome was major hemorrhage defined as a composite of intracranial hemorrhage and fatal bleedings. Net clinical impact was defined as the combination of these 2 endpoints. Results: This analysis included a total of 11,016 patients (5,523 in the ticagrelor-aspirin group, 5,493 in the aspirin group) with a mean age of 65 years, and 39% were women. The reduction of major ischemic events by ticagrelor occurred in the first week (4.1% vs 5.3%; absolute risk reduction 1.15%, 95% CI 0.36%-1.94%) and remained throughout the 30-day treatment period. An increase in major hemorrhage was seen during the first week and remained relatively constant in the following weeks (absolute risk increase ≈0.3%). Cumulative analysis showed that the net clinical impact favored ticagrelor-aspirin in the first week (absolute risk reduction 0.97%, 95% CI, 0.17%-1.77%) and remained constant throughout the 30 days. Discussion: In patients with mild-moderate ischemic stroke or high-risk TIA, the treatment effect of ticagrelor-aspirin was present from the first week. The ischemic benefit of ticagrelor-aspirin outweighs the risk of major hemorrhage throughout the treatment period, which may support the use of 30-day treatment with ticagrelor and aspirin in these patients. Classification of evidence: This study provides Class II evidence that, for patients with mild-moderate ischemic stroke or high-risk TIA, the ischemic benefit of ticagrelor-aspirin outweighs the risk of major hemorrhage throughout the 30-day treatment period.This study is supported by AstraZeneca

A Comparative study for some semi-recursive methods on real-time multibody vehicle dynamics model

Some topological formulations in terms of semi-recursive fashion have been proposed recently to improve computational efficiency in complex multibody systems (MBS). An improved semi-recursive method has been developed by García de Jalón, Kim has introduced a subsystem synthesis method, and Bae has implemented an implicit generalized semi-recursive method. These semi-recursive methods, in which the system topology is used to obtain velocities recursively in an open-loop MBS, are efficient for solving the equations of motion of large-scale multibody models. A numerical comparative study among the aforesaid methods is carried out based on theory, accuracy and efficiency

Is there a correlation between socioeconomic disparity and functional outcome after acute ischemic stroke?

Background To investigate the impact of low socioeconomic status (SES), indicated by low level of education, occupation and income, on 3 months functional outcome after ischemic stroke. Methods We analyzed data from the China National Stroke Registry (CNSR), a multicenter and prospective registry of consecutive patients with acute cerebrovascular events occurred between September 2007 and August 2008. 11226 patients with ischemic stroke had SES and clinical characteristics data collected at baseline and mRS measured as indicator of functional outcome in 3 months follow up. Multinomial and ordinal logistic regression models were performed to examine associations between SES and the functional outcome. Results At 3 months after stroke, 5.3% of total patients had mRS scored at 5, 11.3% at score 4, 11.1% at score 3, 14.4% at score 2, 34.2% at score 1 and 23.7% at score 0. Compared to patients with educational level of ≥ 6 years and non-manual laboring, those < 6 years and manual laboring tended to have higher mRS score (P<0.001). Multinomial adjusted odds ratios (ORs) of outcome in manual workers were significantly increased (ORs from1.38 to 1.87), but OR in patients with less income was not significant. There were similar patterns of association The impact may be stronger in patients aged <65 years (P = 0.003, P<0.001 respectively) and being male (P = 0.001, P<0.001 respectively). Conclusions Our study provides evidence that people who are relatively more deprived in socioeconomic status suffer poorer outcome after ischemic stroke. The influence of low educational level and manual laboring can be more intensive than low income level on 3-month outcome. Health policy and service should target the deprived populations to reduce the public health burden in the society.This study is supported by grants from the Ministry of Science and Technology of the People’s Republic of China (2006BAI01A11, 2011BAI08B01, 2011BAI08B02, 2012ZX09303-005-001, and 2013BAI09B03), a grant from the Beijing Biobank of Cerebral Vascular Disease (D131100005313003) and a grant from Beijing Institute for Brain Disorders (BIBD-PXM2013_014226_07_000084