THE EXTRACTION EQUILIBRIUM MODEL AND SIMULATION OF COUNTERCURRENT SOLVENT EXTRACTION OF Gd-Tb-Dy-HCl-HEH(EHP)-KEROSENE SYSTEM

The extraction equilibrium mathematic models for gadolinium,terbium and dysprosium in HCl-1.5 mol/L HEH(EHP)system covering a relatively wide range of lanthanide concentration and acidity,have been developed.There are four independent variables and nine parameters.The average relative error is 4.56%.A computer program for the simulation of the counter current solvent extraetion process has also been written.Thus,the Gd,Tb and Dy concentrations in both aqueous and organic phase in eaeh stage as well as the aqueous acidity may be calculated.Product purities,distribution ratio and extraction factors may also be obtained thereby.The simulation results so obtained may serve as the referenee data for designing solvent ex- traction processes including those processes providing apart from the conventional outgoing organic stream, outgoing raffinate and an extra outgoing third exit stream either organic or aqueous.

SIMULATION STUDY OF GENERALIZED MINIMUM VARIANCE CONTROL FOR AN EXTRACTION TURBINE

In an extraction turbine, pressure of the extracted steam and rotate speed of the rotor are two important controlled quantities. The traditional linear state feedback control method is not perfect enough to control the two quantities accurately because of existence of nonlinearity and coupling. A generalized minimum variance control method is studied for an extraction turbine. Firstly, a nonlinear mathematical model of the control system about the two quantities is transformed into a linear system with two white noises. Secondly, a generalized minimum variance control law is applied to the system. A comparative simulation is done. The simulation results indicate that precision and dynamic quality of the regulating system under the new control law are both better than those under the state feedback control law.

Tapering-induced enhancement of light extraction efficiency of nanowire deep ultraviolet LED by theoretical simulations

A nanowire(NW) structure provides an alternative scheme for deep ultraviolet light emitting diodes(DUV-LEDs)that promises high material quality and better light extraction efficiency(LEE). In this report, we investigate the influence of the tapering angle of closely packed Al Ga N NWs, which is found to exist naturally in molecular beam epitaxy(MBE) grown NW structures, on the LEE of NW DUV-LEDs. It is observed that, by having a small tapering angle, the vertical extraction is greatly enhanced for both transverse magnetic(TM) and transverse electric(TE) polarizations. Most notably, the vertical extraction of TM emission increased from 4.8% to 24.3%,which makes the LEE reasonably large to achieve high-performance DUV-LEDs. This is because the breaking of symmetry in the vertical direction changes the propagation of the light significantly to allow more coupling into radiation modes. Finally, we introduce errors to the NW positions to show the advantages of the tapered NW structures can be projected to random closely packed NW arrays. The results obtained in this paper can provide guidelines for designing efficient NW DUV-LEDs.

Simulation extractable SNARKs based on target linearly collision-resistant oracle

The famous zero-knowledge succinct non-interactive arguments of knowledge(zk-SNARK) was proposed by Groth in 2016.Typically, the construction is based on quadratic arithmetic programs which are highly efficient concerning the proof length and the verification complexity. Since then, there has been much progress in designing zk-SNARKs, achieving stronger security,and simulated extractability, which is analogous to non-malleability and has broad applications. In this study, following Groth's pairing-based zk-SNARK, a simulation extractability zk-SNARK under the random oracle model is constructed. Our construction relies on a newly proposed property named target linearly collision-resistant, which is satisfied by random oracles under discrete logarithm assumptions. Compared to the original Groth16 zk-SNARK, in our construction, both parties are allowed to use such a random oracle, aiming to get the same random number. The resulting proof consists of 3 group elements and only 1 pairing equation needs to be verified. Compared to other related works, our construction is shorter in proof length and simpler in verification while preserving simulation extractability. The results also extend to achieve subversion zero-knowledge SNARKs.

Estimation of bioaccessibility and potential human health risk of mercury in Chinese patent medicines

Mercury（Hg）, mainly in cinnabar species, has been used in medicine for thousands of years in China, and worldwide concern has been raised on its toxicity. In this work, the amount of bioaccessible mercury in 16 Chinese patent medicines（CPMs） was measured by using an in vitro simulated digestion system, consisting of simulated gastric and intestinal fluid, to investigate the bioavailability of mercury in CPMs and evaluate its potential risk to human health. Total mercury and mercury in the gastrointestinal extracts were measured by inductively coupled plasma mass spectrometry（ICP-MS）. The levels of total Hg in 16 CPMs ranged from not detected to 11.89 mg/g, with a mean value of 1.13 mg/g, while the extractable Hg ranged from not detected to 4.37 μg/g, with a mean value of 0.42 μg/g.Mercury bioaccessibility varied significantly in the investigated CPMs, depending on the ingredient. Compared to the CPMs without cinnabar（2.5%–30.9%）, the percentage of mercury in the gastrointestinal supernatants for CPMs with cinnabar was quite a bit lower（0.037%）. By comparing with the Food and Agricultural Organization/World Health Organization Joint Expert Committee on Food Additives（FAO/WHO） safety guideline, the average daily intake dose（ADD） of Hg in the medicines was then calculated to access the risk of mercury to human health from taking CPMs.