The parameters governing the coefficient of dispersion of cubes in rotating cylinders

Axial dispersion of cubic particles in horizontal, rotating cylinders was investigated using discrete element modelling simulations. We found that, similar to the behavior of spheres, the axial dispersion coefficient of cubes depends on (1) the rotational speed of the cylinder \({\omega }\), (2) the acceleration due to gravity g and (3) the particle size d, satisfying the relationship \({D}_\mathrm {ax}\propto {\omega }^{1-2{\lambda }}{g}^{{\lambda }}{d}^{2-{\lambda }}\) with \({\lambda }\approx 0.15\) (\({\lambda }\approx 0.1\) for beds of spheres) (Third et al. in Powder Technol 203:510–517, 2010). This observation suggested that, although particle shape influences significantly the rate of axial dispersion (cubes disperse almost twice as fast as spheres of equal volume), the parameters controlling the coefficient of dispersion are independent of particle shape.     

Long-term aeration management for improved N-removal via SND in a sequencing batch reactor

Management of the aeration length in a sequencing batch reactor (SBR) can improve N-removal by minimising the amount of organic substrate that is oxidised aerobically. This study investigates the long-term effect of aeration control on N-removal via simultaneous nitrification and denitrification (SND) by a mixed culture in a 2L acetate-fed SBR, using PHB as the electron donor for denitrification. The reactor was operated continuously with automated termination of the aerobic phase after ammonium depletion, using the specific oxygen uptake rate (SOUR) as the control parameter. This resulted in an increase of the organic loading rate (OLR) from 0.33 to 0.59 g BOD g(-1)d(-1). Over the first 12 cycles of operation, the PHB content of the biomass increased three-fold and resulted in a progressively increasing SOUR, which allowed an increased amount of nitrogen removal via SND from 34% to 52%. After one month of continuous operation with controlled aeration, the settling efficiency of the biomass had significantly improved (SVI 70 mL g(-1) X). Long-term oxygen management resulted in biomass with a higher capacity for N-removal via SND and improved settling characteristics. Our results may help to explain long-term historical effects of N-removal capabilities in WWTPs and assist design engineers in choosing an appropriate aeration length and OLR.     

活性炭纤维对水中酸性大红的吸附脱色研究

研究了活性炭纤维(ACF)对水中酸性大红的吸附脱色试验。温度为15℃~20℃,滤速为6mL/min时,浓度为12mg/L的酸性大红脱色率达98％以上。活性炭纤维经20次吸附与解吸实验,吸附脱色性能没有明显降低。与颗粒状活性炭(GAC)相比,活性炭纤维吸附脱色酸性大红的吸附量大,可望作为对吸附脱色酸性大红废水的方法。     

15CrMo钢锻焊锥过渡段焦炭塔的制造

介绍了高桥石化上海炼油厂 1 40万t/a延迟焦化装置焦炭塔的制造 ,通过制造、焊接工艺、热处理试验、工艺和方法及壳体加固措施 ,解决了锻焊的连体锥形封头过渡段制造工艺和超大型设备制造组焊预后热、热处理及埋弧自动焊工艺等技术难题 ,取得了综合性良好的工艺效果。     

焦炭塔塔裙连接结构的探讨

焦炭塔塔裙连接型式对焦炭塔安全使用至关重要，通过对焦炭塔不同塔裙连接型式的安全性对比以及2台直径880mm焦炭塔塔裙连体锻焊件的制造总结，进而探讨在目前国内制造水平下焦炭塔采用连体锻焊结构型式的适用性。     

Φ18mm×3mm20~#钢高压仪表管的钨极氩弧焊

介绍了Φ１８ｍｍ×３ｍｍ ２０＃高压仪表管的氩弧焊焊接工艺，该工艺包括坡口的选用、工艺参数、操作等关键技术。     

飞航导弹总体方案设计专家系统中的求解策略

着重介绍了飞航导弹总体方案设计专家系统(CMDES)的求解策略和推理技术,包括信息传递算法、框架推理、规则推理、方法求解器等。     

楼宇自控系统在民航机场航站楼均设计应用

随着机场建设的不断完善和绿色环保机场概念的提出,楼宇自控系统的设计在机场航站楼中显得尤为重要。航站楼采用了诸多先进的节能措施,在这些效能显著的设备设施基础上,航站楼的楼宇自控系统更是需要从系统设备运行管理的角度着重强调对所辖的航站楼进行科学系统的节能管理。本文从设计角度出发介绍了楼宇自控系统的网络架构、系统集成、各子系统的功能等在航站楼的设计应用。     

Optimisation of storage driven denitrification by using on-line specific oxygen uptake rate monitoring during SND in a SBR.

This study builds on previous experience of maximising the formation of COD as poly-hydroxybutyrate (PHB) and now describes a feedback technique of preserving the use of PHB for denitrification resulting in enhanced nitrogen removal rather than allowing its wasteful oxidation by oxygen. The feedback technique uses on-line SOUR monitoring for detecting the end-point of nitrification and controlling the aerobic phase length accordingly. The laboratory SBR was operated such that all organic substrate (acetate) was rapidly converted to PHB, which then served as the electron donor for nitrogen removal via simultaneous nitrification and denitrification (SND) during the aerobic phase (up to 70% SND). During SBR cycling with a fixed aeration length (240 minutes), PHB was unnecessarily oxidised after ammonium depletion, resulting in little denitrification and poor total nitrogen removal (69%). However, when the aerobic phase length was controlled via the SOUR, up to 1.8 CmM PHB (58 mg L(-1) COD) could be preserved, enabling improved total nitrogen removal (86%). The drop in the SOUR after ammonium depletion was a reproducible event that could be detected even when using raw wastewater and fresh activated sludge. The SOUR-control technique holds promise to build up PHB over a number of SBR cycles. While advanced oxygen-control is used for improved N-removal in several existing WWTPs, this study investigates the importance of oxygen control with relevance to PHB driven SND in sequencing batch reactors.     

弹用高亚音速嵌入式,半嵌入式进气道设计与试验研究

本文介绍了以涡轮喷气发动机为动力装置的飞航式战术导弹的一种新型高亚音速嵌入式、半嵌入式进气道的设计与试验研究结果。提出了弹用高亚音速嵌入式、半嵌入式进气道在弹上的位置、进气道通道截面形状、扩张规律、开口形状、喉道面积、内外唇口以及附面层隔道高度选取等初步设计原则和抽气式测试系统的新的进气道试验技术。