Solubility of β-cyclodextrin in different mixed solvents

The solubility of β-cyclodextrin(β-CD)in ionic liquid/N,N-dimethyl-acetamide(IL/DMAC)mixed solvent and in LiCl/DMAC mixed solvent was investigated at 323.15 K and 353.15 K.The results showed that the solubility of β-CD in IL/DMAC system increased with increasing temperature,but decreased in LiCl/DMAC system.β-CD had the highest solubility in IL/DMAC system with[Cl]- or[Br]- anions.The solubility of β-CD in LiCl/DMAC system was lower than that in IL/DMAC system with [Cl]- or[Br]- anions but higher than that in IL/DMAC system with weak-coordinated anions(e.g[BF4]- or[PF6]-).The effects of substituent groups(benzyl and butyl)of cation and the structure of cations on β-cyclodextrin solubility were also investigated.     

Rational design and low-cost fabrication of multifunctional separators enabling high sulfur utilization in long-life lithium-sulfur batteries

The lithium-sulfur(Li-S) battery with an ultrahigh theoretical energy density has emerged as a promising rechargeable battery system.However,the practical applications of Li-S batteries are severely plagued by the sluggish reaction kinetics of sulfur species and notorious shuttling of soluble lithium poly sulfides(LiPSs) intermediates that result in low sulfur utilization.The introduction of functional layers on separators has been considered as an effective strategy to improve the sulfur utiliz...     

Solute Segregation to Grain Boundaries in Al: A First-Principles Evaluation

Solute-induced grain boundary(GB) strengthening is eff ective in improving the toughness and tensile strength of polycrystalline alloys. In this work, GB segregation behaviors of solute elements in Al alloys and their potential eff ects on GB binding have been systematically investigated from fi rst-principles energetics. The low-energy Σ3(111) and Σ11(113) are immune to vacancy segregation, while high-energy Al GBs, such as Σ13(320), Σ9(221), Σ5(210), and Σ5(310), can attract both vacancies and...     

LUBRICATION FILM FORMATION MECHANISM OF SLIPPER PAIRS IN LOW SPEED HIGH TORQUE HYDRAULIC MOTORS

Pressure-flow analytical formulas of lubrication film of slipper pairs on camshaft connect- ing rod type low speed high torque (LSHT) hydraulic motors are put forward. The bottom surface of slipper pairs is rectangle, and the effect of squeeze flow and pressure differential flow is considered. The dynamic process of lubrication film formation through squeezing is numerically studied by com- puter simulation. Effects of supply pressure, initial lubrication film thickness, velocity damping coef- ficient, loading impact and gravity, etc are studied. Advantages of novel slipper pairs with large oil cavity area are pointed out.     

Palmitic Acid-Lauric Acid/Expanded Graphite as Form-Stable Composite Phase Change Material for Low-Temperature Energy Storage Applications

Low thermal conductivity of binary fatty acid mixture of palmitic and lauric acids(PA-LA) within the value range of 0.15-0.17 W/(m·K) restricts its wide utilization as thermal energy storage material in the active regime of solar heating applications at low operating temperatures. Nevertheless, this mixture as phase change material(PCM) has a suitable phase-change temperature and heat of 36 ℃ and 176.3 J/g, respectively. Hence, the objective of this study is to formulate a novel form-stable comp...     

Quality control for bloom casting of YQ450NQR1 steel

To reduce surface depression of a bloom,the primary cooling intensity was decreased,and the water distribution of mold wide and narrow faces was optimized.The length of secondary cooling zones and the specific water flow were increased,and the water flow distribution among the secondary cooling zones was adjusted to eliminate central defects,such as center looseness,central segregation,and center line cracks.The operation showed that the proportion of surface depression decreased from 37.22% to 2.87%,whereas the proportion of center looseness for < 1.0 increased from 79.71% to 90.70%,the proportion of central segregation for <0.5 increased from 1.45% to 44.19%,and the proportion of center line cracks that are flee increased from 39.13% to 62.79%.The quali-fied blooms are delivered to produce 310 Z-beam,whose yield strength is greater than 450 MPa.     

Coordinating optimization-based sliding mode variable structure control for electro-hydraulic servo system

A sliding mode variable structure control (SMVSC) based on a coordinating optimization algorithm has been developed. Steady state error and control switching frequency are used to constitute the system performance indexes in the coordinating optimization, while the tuning rate of boundary layer width (BLW) is employed as the optimization parameter. Based on the mathematical relationship between the BLW and steady-state error, an optimized BLW tuning rate is added to the nonlinear control term of SMVSC. Simulation experiment results applied to the positioning control of an electro-hydraulic servo system show the comprehensive superiority in dynamical and static state performance by using the proposed controller is better than that by using SMVSC without optimized BLW tuning rate. This succeeds in coordinately considering both chattering reduction and high-precision control realization in SMVSC.     

PI control based on fuzzy set-point weighting tracking for hydraulic crane boom system

A PI control strategy based on fuzzy set-point weighting following was proposed for the active damping control of a hydraulic crane boom system （HCBS）. Two valve-controlled PI controllers, which include a proportional feedforward controller based on fuzzy set-point weighting following and a limited semi-integrator（LSI）, are designed respectively. LSI is used to limit output signal and to prevent wind up at the low frequency of the spectrum. By using a range camera and an electronic feedback control, the tip damping on the HCBS can be adjusted artificially. A collaborative control simulation technique of HOPSAN and MATLAB/SIMULINK is applied to the controller design. Simulation results show that the proposed PI control system has less overshoot as well as faster response. The tip damping on the HCBS during operation is improved.     

Joint Iterative Pilot Assisted Channel Estimation and Detection in Turbo OFDM System

OFDM is a promising technique over mobile wireless channels. Diversity and iterative estimation play an important role in improving the performance of OFDM systems In this article, we develop turbo OFDM system, which employ interleaver at the transmitter to permute information and introduce additional temporal frequency domain diversity. At the receiver, we propose an iterative channel estimation combining MMSE and linear interpolation methods. Simulation results show the iterative gains with common block interleaver used at the transmitter. In order to improve the performance of the system, we develop a special interleaver, called only one cycle interleaver （OOC）, with dynamic detector used at the receiver. Computer simulation results are shown and compared to give some conclusions.     

Evaluation of Young''''s Modulus and Residual Stress of NiFe Film by Microbridge Testing

Microbridge testing was used to measure the Young's modulus and residual stress of metallic films. Samples of freestanding NiFe film microbridge were fabricated by microelectromechanical systems. Special ceramic shaft structure was designed to solve the problem of getting the load-deflection curve of NiFe film microbridge by the Nanoindenter XP system with normal Berkovich probe. Theoretical analysis of load-deflection curves of the microbridges was proposed to evaluate the Young's modulus and residual stress of the films simultaneously. The calculated results based on experimental measurements show that the average Young's modulus and residual stress for the electroplated NiFe films are 203.2 GPa and 333.0 MPa, respectively, while the Young's modulus measured by the Nano-hardness method is 209.6±11.8 GPa for the thick NiFe film with silicon substrate.