Impact of the addition of an enzyme pool on an activated sludge system treating dairy wastewater under fat shock loads

BACKGROUND: The application of lipase‐rich enzyme pools (such as the crude solid enzymatic preparation (SEP) obtained from Penicillium restrictum solid‐state fermentation of agro‐industrial wastes) to activated sludge systems may be an effective strategy for preventing various operational problems. The continuous addition of SEP to the treatment system can become cost‐prohibitive when in situ production and/or storage are factored in. The application of SEP to high‐fat wastewater treatment would only be justified as an emergency measure, such as a sudden increase in the fat content of the bioreactor influent. Therefore, the primary objective of this work was to investigate the efficiency of a crude SEP during fat shock loads, simulated through the periodic addition of dairy industry waste containing high fat concentrations to the feed stock of an activated sludge system, operated in continuous mode. RESULTS: The test bioreactor exhibited a higher average chemical oxygen demand (COD) removal efficiency than the control bioreactor (83% for control and 90% for test) and the fat accumulation in the biological flocs of the test bioreactor was 3.2 times lower than that in the control bioreactor. Turbidity was also lower in the effluent of the test bioreactor (123 and 66 FTU in control and test, respectively) and it had a shorter recovery time between shock loads, especially when the interval between loads was shorter than one month (biweekly and weekly shock loads). CONCLUSION: The addition of SEP during fat overloads in the reactor feed maintained efficient COD removal in the test bioreactor for 270 days without any operational problems. Copyright © 2008 Society of Chemical Industry     

欠驱动系统Pendubot的模糊控制策略

本文针对欠驱动Pendubot机器人系统，提出一种简单可靠的摇起及平衡控制策略。通过利用模糊控制及全状态反馈控制技术来分别设计摇起控制器及平衡控制器，其中模糊摇起控制器的设计使得系统的摇起可靠性得到大大的加强，并缩短了响应时间，两个控制器的转换通过转换装置实现。最后的仿真结果验证了算法的有效性。     

Connecting the second exhaust-heat boiler to the operating first one under the conditions of flow circuits of combined-cycle plants with two gas-turbine units and one steam turbine

Problems arising with connecting the second exhaust-heat boiler to the first exhaust-heat boiler under load in the case of flow circuits of combined-cycle plants of type PGU-450 are considered. Similar problems exist for two-boiler single-turbine units of type PGU-325 and for two-boiler single-turbine units of traditional steampower plants with an output of 200–300 MW upon connection of the second furnace of a two-furnace boiler to the operating first furnace. Analysis of the temperature-induced stressed state and of the cyclic strength of thick-walled elements of the steam-water conduit of PGU-450 and of two-furnace boilers of two-boiler single-turbine units with an output of 200–300 MW (the check valve, the inlet header of the water economizer) is used for determining the steam temperature differences in the high-pressure conduits to the steam turbine and the order of connection of the second exhaust-heat boiler to the operating fist one. Modes of enabling a two-boiler single-turbine unit of a combined-cycle plant, which are most “rigid” from the standpoint of thermal strength, are determined. __________ Translated from élektricheskie Stantsii, No. 2, February 2006, pp. 11–17.     

Aspects of rapid crack propagation in silicon

Fracture experiments with silicon specimens in recent years have shown the need for a new approach to the analysis of rapidly propagating cracks in single crystals. Behaviour and phenomena have been revealed that fracture in these materials is rather different from the fracture of both amorphous and polycrystalline materials. We show that continuum mechanics is insufficient for analyzing crack propagation in single crystals since it is unable to consider atomistic‐scale phenomena. Accordingly, we describe basic phenomena associated with rapid crack propagation in silicon : (i) anisotropic velocity‐dependent R‐curve behaviour, as a key phenomenon dictating atomistic scale behaviour, (ii) crack deflection from one cleavage plane to another as a mesoscopic scale phenomenon in single‐crystal fracture, (iii) the Rayleigh surface wave speed as the limiting crack tip velocity is re‐examined, (vi) the lowest crack velocity in brittle crystals is examined, and finally (v) the interaction between crack path and preferred cleavage planes in single crystals is depicted.     

JETS,PLUMES AND BUOYANT JETS IN STATIC ENVIRONMENT

Turbulence represents an essential aspect in atmospheric and oceanic circulations.In particu-lar,it is a preponderant factor in the dispersion of pollutants of artificial or natural origin.Thevertical turbulent jets,plumes and buoyant jets discharging into static environment is one of themost important and basic flow patterns related with the environment pollution.These flows havenumerous important applications,for example,thrust augmentors,waste disposal plumes fromstacks and combustion systems,and significant problems of turbulent diffusion.     

多台并行随机CIMS可靠性的扩散估计界

ＣＩＭＳ可靠性模型随机研究的突出特点是工作站的并行结构使系统的状态个数呈现指数级增大，同时，并行结构与有限的缓冲库相互交织在一起，这使系统状态呈爆炸趋势，显然，对系统作精确的分析与系统呈现的状态爆炸趋势构成了难以解决的矛盾，如何解决这一矛盾正是ＣＩＭＳ随机理论有待开发的重要课题。我们把扩散近似方法引入到多台并行的ＣＩＭＳ可靠性模型中，以简单的连续过程描述了具有状态爆炸趋势的复杂离散过程，给出了ＣＩ     

复印粉的粉碎分级技术

本文介绍了利用国产气流粉碎机和余气萃取分级制备复印粉的实用技术，并展示了粉碎分级系统和复印粉的电镜照片。     

受控离散事件过程（CDEP）的一种代数分析方法

本文在文［１～３］的基础上，提出了受控离散事件过程（ＣＤＥＰ）的一种代数分析方法，弥补了Ｒａｍａｄｇｅ和Ｗｏｎｈａｍ［１～３］的理论对具体系统的应用缺乏可操作性的缺陷，使得对ＣＤＥＰ动态过程的分析变得更为直观，同时也使控制器的设计过程更具可操作性．     

NUMERICAL SIMULATIONS OF WHOLE FIELD BEHAVIOR FOR ROUND BUOYANT JET

ＮＵＭＥＲＩＣＡＬＳＩＭＵＬＡＴＩＯＮＳＯＦＷＨＯＬＥＦＩＥＬＤＢＥＨＡＶＩＯＲＦＯＲＲＯＵＮＤＢＵＯＹＡＮＴＪＥＴＬｉＷｅｉ，ＨｕａｉＷｅｎ－ｘｉｎ（ＷｕｈａｎＵｎｉｖｅｒｓｉｔｙｏｆＨｙｄｒａｕｌｉｃａｎｄＥｌｅｃｔｒｉｃＥｎｇｉｎｅｅｒｉｎｇ，...