The pressure Kutta condition uses Newton-Raphson iterative process to assure equal pressure between upper and under surfaces at blade trail. This method can avoid the errors by applying Morino's Kutta condition and improve prediction precision of the cavitation shape nearby hydrofoil tip. In this paper, the range and volume of sheet cavitation of 3-D hydrofoils and propeller were predicted by pressure Kutta condition. Cavity calculation results of two methods are compared with observations for propeller.
This paper shows how clocked AC-DC charge pump circuits can be optimally designed to have the minimum circuit area for small form factor vibration energy harvesting. One can determine an optimum number of stages with simple equations and then determine the capacitance of each pump capacitor to have a target output current at a target output voltage. The equations were verified under a wide range of design parameters by comparing the output current with the simulated one. The output current of the circuit designed by the equations was in good agreement with the simulated result, to within 5% for 98% of the 1600 designs with different parameters. We also propose a design flow to help designers determine the initial design parameters of a clocked AC-DC charge pump circuit (i.e., the number of stages, capacitance per stage, and the total size of rectifying devices) under the condition that the saturation current of a unit of the rectifying device, clock frequency, amplitude of the voltage generated by the energy transducer, target output voltage, and target output current are given. SPICE simulation results validated theoretical results with an error of 3% in terms of the output current when a clocked AC-DC charge pump was designed to output current of 1 μA at 2.5 V from a vibration energy harvester with an AC voltage amplitude of 0.5 V.
Although the detection of perfluorocarbons in environmental matrices such as dust has been used to quantitatively detect cosmetics in literature, the variety and complexity of cosmetic matrices necessitates the development of a new and systematic sample preparation method that is tailored to a specific type of cosmetic product. This study describes a highly applicable method for simultaneous determination of 17 perfluorinated compounds (PFCs), including 9 perfluoro carboxylic acids and 8 perfluorosulfonic acids in cosmetic products via ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The samples were dispersed using saturated sodium chloride or tetrahydrofuran, followed by liquid-liquid extraction with acetonitrile. The extracts were purified successively by potassium ferrocyanide-zinc acetate solution and solid-phase extraction (SPE) on a weak anion exchange (WAX) cartridge. The PFCs were separated by a Phenomenex Kinetex C18 chromatographic column and quantified via internal standard method in multiple reaction monitoring mode (MRM) in negative electron spray ionization (ESI-). The limits of quantification were 0.07–0.2 ng/g. The recoveries ranged from 70.1% to 114.7%, with relative standard deviations in the range of 2.0–19.1%. The method was applied to cosmetic samples in the Chinese market. In this study, the total concentration of PFC ranged from 0 to 10.8 ng/g.
Human exposure to polyfluoroalkyl substances (PFASs) via cosmetics has been of increasing concern due to the tremendous detrimental health impacts of PFASs.
A simple numerical method is presented for predicting the steady performance of ducted controllable pitch propellers,in which a potential based surface-panel method is applied both for the propeller and duct.The hydrodynamic interaction between the propeller and the duct is solved in calculating influence coefficients.Numerical calculations are carried out for JD simplified ducted propeller series.The numerical results are compared with experimental data and good agreement is obtained.
Abstract A ship hull model with all accessories is used to simulate the wake field of the propeller of a twin propeller ship in a large circulating water channel.The similarity of propeller wake field is guaranteed.The influence of air content in water on pressure fluctuation by cavitating propeller is studies.The cavity form of propeller was observed under the condition of different air content in water.The pressure fluctuations induced by cavitating propeller behind ship hull is also measured.The results showed that the air content has a significant influence on the pressure fluctuations. Each measuring points and each order frequency of pressure fluctuations amplitudes increase with the decrease of air content.The main reasons of influence of air content on pressure fluctuations are analyzed.It is proposed that how to set the air content in the model tests.
Sir Run Run Shaw Hospital (SRRSH) is the first to make joint commission international (JCI) known to people in China. It gets the gist of the JCI accreditation standards and earnestly practices with JCI mentality. The tracing methodology used during JCI survey features detailed and professional examination on every inch of quality and safety on clinical care, nursing, medical technologies, and general support. The highlight of SRRSH lies in the visualization of closed-loop system, where the status of every step is presented in the process map, and any missing step triggers alert to ensure patient safety. "In terms of patient safety, SRRSH accepts only 'standard compliance' and leaves no room for 'not bad'," said Dr. Cai Xiujun, president of the hospital. Starting from January 2015, SRRSH has reported fall cases to National Database of Nursing Quality Indicator every month to hold ourselves against international standards and expectations.
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