A fast and reliable numerical method for analyzing loaded rolling element bearing displacements and stiffness

The load-displacement relation for rolling element bearing is a system of nonlinear algebraic equations describing the relationship of bearing forces and displacements needed to compute the bearing stiffness. The computed bearing stiffness is typically employed to represent the bearing effect when modeling the whole geared rotor system to optimize the system parameters to minimize the unwanted vibrations. In this study, a robust numerical scheme called the energy method is developed and applied to solve for the bearing displacements from the potential energy of the bearing system instead of solving these nonlinear algebraic equations using the classical numerical integration. The proposed energy method is based on seeking the minimal potential energy derived from the theory of elasticity that describes the potential energy as a function of the displacements of inner ring of rolling bearing relative to the housing support structure. Therefore, solving the system of nonlinear algebraic equations is converted into solving a global optimization problem in which the potential energy term is the objective function. The global optimization algorithm produces the bearing displacements that make the potential energy function of bearing system minimum. Parameter studies for bearing stiffness as the explicit expressions of bearing displacements are conducted with the varying unloaded contact angles and the varying orbital positions of rolling elements. The analysis applying the energy method is shown to yield the correct solution efficiently and reliably

CHINA ENERGY LABEL: A strategy to encourage energy conservation and the challenge ahead in power markets

ABSTRACT This paper aims to elucidate China energy label and《The minimum allowable values of the energy efficiency and energy efficiency grades for room air conditioners 》 implemented recently (2005). Energy efficiency ratio (EER) considered in this standard was compared with coefficient of performance (COP), based on it, two air-conditioners with different EER were calculated to be contrasted by their total cost during the operational life. At the same period, the content, significance and result of the energy standard was analyzed. The results show that air-conditioners with higher EER can be more economical, and they can obtain better qualities as well as utilization effects. Also, this standard determines the energy efficiency grade index of room air-conditioners below 14 kW and the market entrance admission index of energy efficiency. Starting this standard requires that each air-conditioner should have an energy label, thus market transformation goals can be achieved, consequently, it will accelerate the advancement of enterprises and reinforce the energy-saving management of the government. However, designers, manufacturers and high efficiency product sellers in the power market will be challenged

Highly efficient blueish-green fluorescent OLEDs based on AIE liquid crystal molecules : From ingenious molecular design to multifunction materials

In order to seek the balance point between liquid crystallinity and high efficiency emission, two novel aggregation-induced emission-based (AIE) liquid crystal materials of TPE-PBN and TPE-2PBN, which contain a tetraphenylethene derivative as the emission core and a 4-cynobiphenyl moiety as the mesogenic unit, were designed and prepared. Both simple molecules showed a mesophase at high temperature as evidenced by polarised optical microscopy (POM), differential scanning calorimetry (DSC) and temperature-dependent X-ray diffraction (XRD). Simultaneously, TPE-PBN and TPE-2PBN presented clear AIE characteristics in the blueish-green region and achieved a high emission quantum efficiency of 71% and 83% in the solid state, respectively. Due to the self-assembly properties of thermotropic liquid crystals, both compounds showed higher hole mobilities in the annealed films than in pristine films. Employing TPE-PBN and TPE-2PBN as the emitting materials, both non-doped devices and doped devices were fabricated. The TPE-PBN-based doped OLEDs showed a better device performance with an external quantum efficiency (EQE) of 4.1% which is among the highest EQEs of blue AIE fluorescent OLEDs

Influence of synthetic superparamagnetic iron oxide on dendritic cells

Yongbin Mou1, Baoan Chen2, Yu Zhang3, Yayi Hou4, Hao Xie4, Guohua Xia2, Meng Tang5, Xiaofeng Huang1, Yanhong Ni1, Qingang Hu1,6 1Central Laboratory of Stomatology, Stomatological Hospital Affiliated Medical School, Nanjing University, 2Department of Hematology, Zhongda Hospital, Medical School, Southeast University, 3State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory for Biomaterials and Devices, Southeast University, 4Immunology and Reproductive Biology Laboratory, Medical School, Nanjing University, 5Laboratory of Environmental Medicine and Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, People's Republic of China; 6Leeds Dental Institute, Faculty of Medicine and Health, University of Leeds, Leeds, UK Background: This study investigated the influence of synthetic superparamagnetic iron oxide (SPIO) on dendritic cells and provides a possible method for labeling these cells. Methods: SPIO nanoparticles were prepared, and their morphology and magnetic properties were characterized. The particles were endocytosed by dendritic cells generated from mouse bone marrow. Labeling efficiency and cellular uptake were analyzed by Prussian blue staining and quantitative spectrophotometric assay. Meanwhile, the surface molecules, cellular apoptosis, and functional properties of the SPIO-labeled dendritic cells were explored by flow cytometry and the mixed lymphocyte reaction assay. Results: The synthetic nanoparticles possessed a spherical shape and good superparamagnetic behavior. The mean concentration of iron in immature and mature dendritic cells was 31.8 ± 0.7 µg and 35.6 ± 1.0 µg per 1 × 106 cells, respectively. After 12 hours of incubation with SPIO at a concentration of 25 µg/mL, nearly all cells were shown to contain iron. Interestingly, cellular apoptosis and surface expression of CD80, CD86, major histocompatibility II, and chemokine receptor 7 in mature dendritic cells were not affected to any significant extent by SPIO labeling. T cell activation was maintained at a low ratio of dendritic cells to T cells. Conclusion: SPIO nanoparticles have good superparamagnetic behavior, highly biocompatible characteristics, and are suitable for use in further study of the migratory behavior and biodistribution of dendritic cells in vivo. Keywords: superparamagnetic iron oxide, dendritic cell, cell labelin

Controlling the emission efficiency of blue-green iridium (iii) phosphorescent emitters and applications in solution-processed organic light-emitting diodes

We show that the emission efficiency of blue-green phosphorescent emitters can be controlled through coupling of the excited state to vibrational modes. We controlled this vibrational coupling through choice of different ligands and as a result, complexes with CF3-groups on the ancillary ligand were essentially non-emissive (ΦPL 50%). Emission of the complexes can be drastically improved (30 times higher ΦPL compared to degassed solution for the CF3-containing complexes) by blending them with an inert solid host such as PMMA, which mitigates metal-ligand vibrations. Solution-processed organic light-emitting diodes made from these materials showed efficiency as high as 6.3%

Affirmative action in education and Black Economic Empowerment in the workplace in South Africa since 1994: policies, strengths and limitations

This paper explains the concepts of Affirmative Action (AA) and Black Economic Empowerment (BEE) and the policies developed in post-Apartheid South Africa. It compares it to similar policies adopted in different contexts in Malaysia, India and the U.S.A. It explains and critiques the South African policies on AA and BEE, its history since 1994 and how class has replaced race as the determinant of who succeeds in education and the workplace. It analyses why these policies were essential to address the massive racial divide in education and the workplace at the arrival of democracy in 1994, but also why it has been controversial and racially divisive. The strengths and limitations of these policies are juxtaposed, the way it has benefitted the black and white elites, bolstered the black middle-class but has had little success in addressing the education and job futures of poor, working class black citizens in South Africa. The views of a number of key social analysts in the field are stated to explain the moral, racial, divisive aspects of AA in relation to the international experience and how South Africa is grappling with limited success to bridge the divide between the rich and poor