A nonlinear pi(d) controller

The PID control algorithm remains the most widely used in the process industries. This is due to its simplicity (three tuning parameters, fixed structure) and its ability to satisfy the majority of process control needs. Here, a new nonlinear algorithm (the PI(D)) is presented, which maintains the simplicity of the PID, but is nevertheless able to outperform it in both load and set point changes. Tuning formulae and response curves for the PI(D) controller are presented.     

A compatibility study of waste poly(ethylene-terephthalate) with poly(vinylchloride)

Mixtures of PET and PVC were prepared in three different compositions by a solution blending technique. A plasma surface modification method was applied to PET powder surfaces in order to enhance the miscibility of both components because of their mutual insolubility. The intrinsic viscosities of blends were measured in a phenol/tetrachloroethanemixed solvent system. The degree of compatibility of blends was characterized by the use of the parameter Δb, as derived by Krigbaum and Wall. © 1993 John Wiley & Sons, Inc.     

Depolymerization of poly(ethylene terephthalate) waste

Poly(ethylene terephthalate) waste was depolymerized with ethylene glycol in the presence of different catalysts, two conventional metal catalysts (zinc acetate and lead acetate) and two alkalies (sodium carbonate and sodium bicarbonate). The resulting monomer bis(2‐hydroxy ethylene terephthalate) was characterized by thin layer chromatography, melting point, IR spectroscopy, differential scanning calorimetry, and elemental analysis. The results show that the qualitative and quantitative yields of the monomer obtained with alkalies as catalysts were most comparable with the conventional heavy metal catalysts, thus providing a further advantage for the recycling of polyester waste for the cause of environmental pollution abatement. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1765–1770, 2002     

Blends of plasticized poly(vinyl chloride) and waste flexible poly(vinyl chloride) with waste nitrile rubber powder

Blends of poly(vinyl chloride) (PVC) with varying contents of plasticizer and finely ground powder of waste nitrile rubber rollers were prepared over a wide range of rubber contents through high‐temperature blending. The effects of rubber and plasticizer (dioctyl phthalate) content on the tensile strength, percentage elongation, impact properties, hardness, abrasion resistance, flexural crack resistance, limiting oxygen index (LOI), electrical properties, and breakdown voltage were studied. The percentage elongation, flexural crack resistance, and impact strength of blends increased considerably over those of PVC. The waste rubber had a plasticizing effect. Blends of waste plasticized PVC and waste nitrile rubber showed promising properties. The electrical properties and LOI decreased with increasing rubber and plasticizer content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1552–1558, 2004     

从β-胸苷出发的司他夫定的合成工艺研究

首先β-胸苷与1.5mol的三苯基氯甲烷和1.5mol的吡啶在DMF中反应,生成5′-位羟基的醚化产物(2);化合物2再在三乙胺作用下与2mol的甲烷磺酰氯反应制成甲磺酸酯(3);然后,化合物3在乙醇中与等摩尔的氢氧化钠作用,制备成氧桥化合物(4);化合物4在DMSO中,在2mol的甲醇钠作用下,生成消除反应产物5;化合物3也可在DMSO中与4mol的甲醇钠作用,一步直接得到消除产物5;最后,化合物5脱保护制备得到司他夫定(d4T,1)。当合成采取“β-胸苷→2→3→4→5→1”路线时,五步反应总收率为74%。当合成采取“β-胸苷→2→3→5→1”路线时,四步反应总收率为70%。     

废轮胎(橡胶)热裂解回收利用的新进展

介绍了废轮胎(橡胶)热裂解回收利用所获得的政策支持。分析了废轮胎(橡胶)热裂解工艺水平的提高,如正压改微负压,采用缺氧和无氧技术等。总结了废轮胎(橡胶)在设备方面的改进与提高。     

变压吸附(PSA)废气的回收利用

针对变压吸附中的逆放气与解析气的排放污染环境,回收占用空间大,作者从实际工艺出发,考虑上下游装置实际情况,本装置存在废气回收利用的可能,经过实际改造后投用效果明显,既解决了废气污染,又实现了节能减排的目的.     

聚d,l-乳酸的合成

本文分别以氧化锌、氯化亚锡和辛酸亚锡为催化剂，采用两部法合成了聚d,l-乳酸。用化学滴定法和粘度法测定了产物相对分子质量，并以红外光谱和DSC对产物进行了表征。结果表明所得到为无定形聚乳酸，Tg为53．3℃。     

SPURIOUS REGRESSIONS BETWEEN I(d) PROCESSES

Abstract. This paper develops an analytical study for the nonsense or spurious regressions that are generated by quite general integrated (of order d) random processes. In doing this, we generalize the work of Phillips (Understanding spurious regressions in econometrics. J. Econ. 33 (1986), 311–40) who provided an analytical study of linear regressions involving only I(1) stochastic processes. Our generalization of Phillips' work to the I(d) case is made employing fractional differencing techniques.     

甲醇制聚甲氧基二甲醚产业在煤化工转型中的机遇探讨

论述了新产品聚甲氧基二甲醚(DMMn)产业背景、产品性质、用途、市场空间、生产技术、产业经济性,认为该产品用于清洁柴油调和及生产,能够大幅降低机动车尾气中污染物排放,具有很好的经济性。     

微生物法处理含铬废水

采用大肠杆菌对含铬废水进行生物处理，研究其在不同条件下除铬(Ⅵ)的能力。实验结果表明，该菌的适用范围广，处理含铬废水功能强。在菌废比为1：1时，温度为37℃，pH值在7左右，48h后对100mg/L的含铬废水去除率可达99％。     

A novel way to treat refractory waste: Sonication followed by wet oxidation (SONIWO)

The effectiveness of the hybrid system sonication followed by wet oxidation (SONIWO) to treat otherwise refractory waste has been demonstrated. In such a hybrid system homogeneous CuSO₄ catalyst was found to be very efficient.     

Renewable (waste) material based polyesters as plasticizers for adhesives

The aim of the presented work was to replace phthalate based plasticizers with environmentally friendly materials to provide similar properties for poly(vinyl acetate) (PVAc) adhesives.Polyesters synthesized from the liquefied wood (PE-LW) and depolymerized polyethylene terephthalate (PE-PET) were used as renewable raw materials and evaluated as plasticizers used in PVAc dispersion adhesives for flooring applications. As a reference plasticizer, 1,2,3-triacetoxypropane was used.PVAc adhesives were evaluated with respect to solids content, viscosity, glass transition temperature (T_g), tensile shear strength and binding strength.TGA analysis showed significant differences between the thermal stability of added polyesters and the commercial plasticizer. Samples prepared with PE-PET exhibit the best thermal stability even with an increase of 25% PE-PET. The addition of coalescing agents or plasticizers leads to a temporary softening of the PVAc polymer and a decrease in the glass transition temperature.The type and content of plasticizer have great influence on wood–wood binding strength, tensile strength and elongation.The requirements for the mechanical properties of adhesives were fulfilled by the compositions containing 8.8% (w/w) of PE-PET and 20% (w/w) of PE-LW.     

Questions begging for answers (Part V): Fatty waste

Oil mills and refineries generate fatty waste, but the disposal of this waste is far from optimal. By hydrolysing this waste at elevated temperature, its fatty matter it is converted into acid oils and an aqueous effluent. Setting up a chain of hydrolysis units would be a profitable business, provided it takes a service company approach.     

Recovery of reusable poly(vinyl chloride) from plastics waste

Solvent recycling of poly(vinyl chloride) (PVC), on the basis of the cyclohexanone/n-hexane system, is further studied. By also using water during the washing stage, hexane quantities employed and solvents separation costs involved are drastically reduced. The modification proposed does not result in any alteration of the main characteristics of the process which further can be extended to rigid PVC pipes. No degradation effects were detected while the polymer recycled exhibits mechanical properties comparable with those of the virgin grade PVC especially with waste material of low additives content. Nevertheless, even from pipes, the polymer recovered proved quite suitable for similar applications.     

过磷酸钙生产三废的治理

采用空塔喷淋吸收气体中的氟 ,吸收效率高 ,散热好 ,排放尾气中的氟含量低于 GBJ4 73标准。氟硅酸制氟硅酸钠 ,氟硅胶经压滤后晒干加入磷肥 ,稀盐酸制矿浆。三废均得到利用 ,改善了环境 ,年增加收入 36万元