WC-Co cemented carbides were prepared by liquid-state sintering of in situ synthesized composite powders with a constant Co content but different carbon concentrations, and with different size scales of VC particles as grain-growth inhibitor. With an optimized carbon addition and doping with microscale VC particles, an ultrahigh fracture strength with a mean value above 5000 MPa was achieved for cemented carbides. By detailed crystallographic analysis of the configuration and interactions of the WC, Co and VC phases, the effects of VC particle size on the microstructure and mechanical properties of cemented carbides are identified. The mechanisms by which the fracture strength depends on the VC particle size contain the effects on the changes in Co binder distribution, atomic matching at the phase boundary and WC grain size. The dominant factors for ultrahigh fracture strength of cemented carbides are proposed.
Compared with human corneas, porcine corneas exhibited a similar nonlinear behaviour but lower stiffness values. The biomechanical parameters of porcine cornea obtained from this test could be applied to numerical simulations of refractive surgery procedures and lay a foundation for pig-to-human corneal xenotransplantation.
In order to meet increasingly stringent discharge standards, new applications and control strategies for the sustainable removal of nitrogen from wastewater have to be implemented. In the past years, numerous studies have been carried out dealing with the application of fuzzy logic to improve the control of the activated sludge process. In this paper, fuzzy control strategies of predenitrification systems are presented that could lead to better effluent quality and, in parallel, to a reduction of chemicals consumption. Extensive experimental investigations on lab scale plant studies have shown that there was excellent correlation between nitrate concentration and ORP value at the end of the anoxic zone. Results indicated that ORP could be used as an on-line fuzzy control parameter of nitrate recirculation and external carbon addition. The optimal value of ORP to control nitrate recirculation and external carbon addition was - 86 +/- 2 mV and - 90 +/- 2 mV, respectively. The results obtained with real wastewater also showed the good performance and stability of the fuzzy controllers independently from external disturbances. The integrated control structure of nitrate recirculation and external carbon addition in the predenitrification system is also presented.
We propose a convenient, inexpensive technique to monitor the fast early stage of catastrophic optical damage (COD) in 808-nm high-power laser diodes (LDs). Using an optical system based on the 1550-nm laser diode illuminant and photodiode, we measured the facet reflectivity, which gives information about the surface morphology of the output facet with a temporal resolution of 2 ns, allowing us to trace the rapid early COD process in a transient, real-time mode. The formation of the detected 4-μm-long COD damaged area, which caused a local uneven surface at the output facet and a rapid drop in facet reflectivity at 1550 nm from 28% to 2%, was completed within 20–30 ns, 10 ns shorter than that in the longer-wavelength devices.
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