Valley打浆预处理制备微晶纤维素

为加快酸液对纤维素的渗透效率,提高酸水解反应平均速率,减少酸用量、缩短酸水解反应时间,本研究以针叶木溶解浆为原料,通过Valley打浆机对纤维原料进行预处理,探讨Valley打浆对盐酸水解产物微晶纤维素(MCC)质量的影响。结果表明,Valley打浆后MCC平均粒径随打浆度的提高逐渐减小,打浆度为53°SR时,平均粒径由52.116μm降低至38.675μm,且粒径分布更加集中,MCC结晶度变化不大。采用响应面法优化得到Valley打浆和酸水解最佳工艺,在保证MCC粒径和结晶度与未打浆预处理相近的情况下,Valley打浆后酸液用量减少了16.67%,反应时间缩短了42.86%。由此可知,Valley打浆预处理可以提高酸液对纤维素的可及性,实现了对MCC粒径的有效调控,同时降低酸水解负荷。     

金属针布和高速梳理是高产梳棉机发展的两大要素--纪念我国高产梳棉机研究试验工作组成立45周年

分析了金属针布和高速梳理在高产梳棉机发展中的重大作用,并介绍了针布新品的开发。     

酸法制备芦苇微晶纤维素工艺的研究

探讨以芦苇浆粕为原料制备芦苇微晶纤维素的可行性及工艺条件.用HCl为溶剂采用正交实验法对制备条件进行研究.结果表明,最佳制备工艺条件为:HCl质量分数6％,水解时间60min,水解温度80℃,液比1∶10;其中水解温度的影响较大,水解产物聚合度(DP)为270.6 L/g,结晶度为73.2％,得率为85.4％;红外光谱和X射线能谱分析表明,所得产物为纤维素Ⅰ型,即微晶纤维素.     

Contour finding by means of subjective tests

Abstract

A special method has been found and used for the rapid finding of the contours in a natural image. A reference contour image was thus formed by a subjective test. The reference contour image can be further adopted as an objective criterion for other contour‐finding algorithms.     

A comparison of chitosan-silica and sodium starch glycolate as disintegrants for spheronized extruded microcrystalline cellulose pellets

Chitosan-silica coprecipitate (C-S) has recently been proposed as a tablet disintegrant. In this study we compared it with a 1:1 physical mixture of chitosan and silica (C/S) at the same composition as the coprecipitate, and with the widely used commercial disintegrant sodium starch glycolate (SSG), as regards to its behavior in spheronized extruded pellets of microcrystalline cellulose (MCC) containing hydrochlorothiazide as a typical poorly water-soluble drug. In all three cases, possible synergism between the disintegrant (0–5%) and sorbitol (0–50%) was also evaluated. All the formulations examined exhibited appropriate morphology and had satisfactory mechanical and flow properties. Drug release depended mainly on sorbitol content, however C-S accelerated drug release at all sorbitol levels (the fastest release was from 50% sorbitol pellets with C-S, which disintegrated), whereas C/S did not vary drug release from pellets, and SSG depressed drug release, especially from 50% sorbitol pellets.     

基于集成构架的智能MCC在钾肥项目中的应用

结合国投新疆罗布泊钾盐有限责任公司年产120万吨钾肥项目,介绍了集成架构理念,智能MCC控制方式,从顶层工作站对底层电机监控的实现.     

Study on the influence of three-grid assembly thermal deformation on breakdown times and an ion extraction process

In order to study the influence of three-grid assembly thermal deformation caused by heat accumulation on breakdown times and an ion extraction process,a hot gap test and a breakdown time test are carried out to obtain thermal deformation of the grids when the thruster is in 5 k W operation mode.Meanwhile,the fluid simulation method and particle-in-cell-Monte Carlo collision(PICMCC) method are adopted to simulate the ion extraction process according to the previous test results.The numerical calculation results are verified by the ion thruster performance test.The results show that after about 1.2 h operation,the hot gap between the screen grid and the accelerator grid reduce to 0.25–0.3 mm,while the hot gap between the accelerator grid and the decelerator grid increase from 1 mm to about 1.4 mm when the grids reach thermal equilibrium,and the hot gap is almost unchanged.In addition,the breakdown times experiment shows that 0.26 mm is the minimal safe hot gap for the grid assembly as the breakdown times improves significantly when the gap is smaller than this value.Fluid simulation results show that the plasma density of the screen grid is in the range 6?×10~(17)–6?×?10~(18) m~(13) and displays a parabolic characteristic,while the electron temperature gradually increases along the axial direction.The PIC-MCC results show that the current falling of an ion beam through a single aperture is significant.Meanwhile,the intercepted current of the accelerator grid and the decelerator grid both increase with the change in the hot gap.The ion beam current has optimal perveance status without thermal deformation,and the intercepted current of the accelerator grid and the decelerator grid are 3.65 m A and 6.26 m A,respectively.Furthermore,under the effect of thermal deformation,the ion beam current has over-perveance status,and the intercepted current of the accelerator grid and the decelerator grid are 10.46 m A and 18.24 m A,respectively.Performance test results indicate that the breakdown times increase obviously.The intercepted current of the accelerator grid and the decelerator grid increases to 13 m A and 16.5 m A,respectively,due to the change in the hot gap after 1.5 h operation.The numerical calculation results are well consistent with performance test results,and the error comes mainly from the test uncertainty of the hot gap.     

智能MCC控制保护管理装置在厂用电系统中的应用

结合智能MCC控制保护管理装置在贵州大龙电厂扩建工程中的应用,详细介绍了智能MCC控制保护管理装置的基本组成和主要功能。     

热连轧液压泵站控制系统设计与应用

根据热连轧精轧机组HAGC(液压自动厚度控制系统)液压泵站控制系统连续工作时间长、可靠性要求高、信号复杂的特点,以ABB公司AC800M型PLC为基础,对液压泵站的硬件构成、工作过程和程序结构进行设计.该液压泵站控制系统控制精度高、可靠性强,完全满足连轧机液压泵站控制要求,已经成功通过模拟调试,并将应用于生产实际.     

一种多功能智能低压电动机继电器的研制

本文介绍一款为满足低压电动机控制中心(MCC)智能化要求而设计开发的保护测控装置——智能电动机继电器,它采用高性能混合信号ISPFLASHMCU微控制器,集保护、测量、控制、显示、通讯等众多功能为一体,具有完善的保护测控功能。本文着重介绍其保护功能,并分析装置的软硬件构成。