多品种小批量生产环境下基于约束管理的混流制造运行控制技术研究

在多品种小批量生产环境中,现有的、以适应大批量重复型生产过程为主的混流制造技术难以得到推广,为实现此类生产环境下的精益化改造,出现了基于混流路径的混流制造新模式.在研究该模式总体架构的基础上,提出多品种小批量生产环境下基于约束管理的混流制造运行控制机制,并就混流路径规划、资源瓶颈识别与动态瓶颈管理等关键技术进行探讨,为进一步的研究应用提供基础.     

Natural attenuation and characterization of contaminants composition in landfill leachate under different disposing ages

Chemical Oxygen Demand (COD) composition in landfill leachate would vary as the disposal time extended. Leachates with different ages were collected from Laogang Refuse Landfill of Shanghai, the largest landfill in China with a placement scale of 7600 t refuse per day. To characterize COD composition in leachate, samples were size-fractioned into suspended fractions (> 0.45 μm), colloid fraction (0.45 μm < fraction < 1 K Da MW) and dissolved fractions (< 1 KDa MW) based on the molecular weight distribution. The fractions < 0.45 μm (including colloid fraction and dissolved fractions) in leachate were further divided into 6 fractions, i.e. hydrophobic bases (Ho-base), hydrophobic acids (Ho-acid), hydrophobic neutral (Ho-neutral), hydrophilic bases (Hi-base), hydrophilic acids (Hi-acid) and hydrophilic neutral (Hi-neutral). It was found that the ratio of TOC/TC in leachate decreased over time, indicating that the percentage of organic matters in leachate decreased as the disposal time extended. It was also observed that the hydrophobic fraction accounted to about 50% of the total matters presented in the fraction < 0.45 μm of all leachate samples. The main components in < 0.45  μm fraction were the Ho-acid, Hi-acid and Hi-base fractions. The percentage of Ho-acid in leachate decreased from 60.8% (2 a) to 43.2% (12 a). In addition, leachate with different ages was categorized into 3 phases according to the results of Principle component analysis (PCA). TOC/COD ranges of leachate in periods I, II and III were 40-54.6%, 16.9-41.3% and 10-38.9%, respectively, indicating that the COD contribution of non-carbon reduction substances increased over time in leachate. Hence, the corresponding landfill leachate treatment process should be modified according to the leachate characterization. The results obtained in this study might provide the important information for modeling, design, and operation of landfill leachate treatment systems.     

Simulating dynamic load of naturally occurring TOC from watershed into a river

Naturally occurring total organic carbon (TOC) is an important feature of stream water quality. This study investigates the dynamic load of TOC from the deep creek watershed into the lower St. Johns River (LSJR), FL, USA, using numerical simulations and field measurements. An existing St. Johns River watershed assessment model for simultaneous loading of nutrients from watersheds into rivers is modified to include the TOC component for the purpose of this study. Three simulation scenarios (i.e., daily, monthly, and annually) are performed to estimate the dynamic load of TOC in response to rainfall events. Simulations show that rainfall events have decisive effects on TOC loads from the Deep Creek watershed into the LSJR. In general, the highly frequent the rainfall events occur, the higher the TOC loads into the river. Simulations also illustrate that effects of rainfall events on daily changes of TOC are minimal in winter, but are profound in late summer. Results suggest that TOC load into the river is not only a rainfall-driven but also a temperature-driven biological process.     

Treating emulsified waste containing mineral oils and alkylphenolethoxylate by membrane and acid-heating processes

We applied a membrane process to treat emulsified industrial waste with mineral oils and alkylphenolethoxylate (APE). Besides the membrane process, we also investigated acid-heating processes for easy introduction into small factories. The present studies were carried out using factory waste for a practical application. In the NTU-2120 membrane process, 99.0 to 99.1% of total organic carbon (TOC) and 97.1 to 98.2% of chemical oxygen demand (COD) were removed from the waste, demonstrating the efficacy of the waste treatment. Permeate fluxes were reduced by 60 to 80% until the volume reduction factor reached 10. The permeate flux was governed by the gel polarization model, and the specific resistance of the gel layer became greater with pressure. Regeneration of the used membrane by the back-pressure wash method completely restored the membrane capacities. The acid-heating process (pH<3, temperature >70°C) reduced TOC by 96.0% and COD by 92.3%, demonstrating waste treatment efficacy similar to that of the membrane process.     

运用约束理论优化汽车生产企业零件供应管理

介绍了约束理论的基本原理，然后根据约束理论，找出生产供应系统的瓶颈，对其予以解决，收到了明显的效果，同时借助案例分析，以求在未来汽车企业供应系统中推广应用。     

二氧化氯在水处理中对有机物的去除研究

以地表水为水源的玫出水为研究对象，探讨以二氧化氮为消毒剂对饮用水中总有机碳和四氯化碳及三氯甲烷的去除效果。结果表明二氧化氮为消毒剂不会引起出厂水中四氯化碳及三氯甲烷的增加。对出厂水中总有机碳也有一定的去除能力，是获得优质饮用水的有效给水处理工艺。     

Artificial groundwater treatment: biofilm activity and organic carbon removal performance

The artificial recharge of sand aquifers with raw source waters is a means both explored and utilised by many water utilities to meet the future potable water demands for increasing urban populations. The microbial ecology within these systems is however, poorly understood, as is the role that microbial biofilms play in the quality of finished water. Knowledge of the ability of biofilm bacteria to metabolise natural organic matter (NOM) is limited, particularly in respect to the degradation of normally recalcitrant hydrophilic and hydrophobic humic acid fractions by sessile and planktonic microbial consortia within sand aquifer systems. To simulate the artificial recharge of sand aquifers that were proposed for the Greater Stockholm Area, four separate 4 m deep sand columns were fed raw lake water and examined over a 45-week study period. The simulated aquifer system (hydraulic retention time 9-16 h) demonstrated the removal of total organic carbon (TOC) (10+/-5%), direct total counts (DTC) of bacteria (74+/-11%), heterotrophic plate count (HPC) bacteria (87+/-5%) and assimilable organic carbon (AOC) (87+/-5%), thereby fulfilling an important barrier function, except for the removal of TOC. Hydrophilic humic acid fractions were more readily metabolised by microbiota (HPC and EUB338-positive cells) harvested from the raw source water (SSM-W), whilst hydrophobic humic acid fractions promoted higher activity by microbiota harvested from the sand matrix (SSM-S). The apparent low activity demonstrated by biofilm microbiota (approximately 40% and 25% of DTC were positive to EUB338 probing for sand matrix and slide biofilms, respectively) could be attributed to the highly recalcitrant nature of the organic loads, whilst at the same time explain the poor removal of TOC. Following nutrient activation (by the PAC assay) nonetheless, a 3-fold increase in the percentage of EUB-positive bacteria was observed on glass slides. Furthermore, the incubation of SSM-S with R2A increased probe-active cells from 57+/-8% to 75+/-7% of DTC and at the same time increased SSM-W from 38+/-8% to 50+/-10%. Whilst these results may imply a good potential for the biological treatment of water by shallow sand aquifers, further work should address the poor removal of TOC observed in this study.     

Improvement of oxidative decomposition of aqueous phenol by microwave irradiation in UV/H2O2 process and kinetic study

2.5GHz of microwave irradiation can cause a considerable improvement of oxidative decomposition of aqueous phenol in a UV/H2O2 system. The experimental results showed that the microwave irradiation can raise both the phenol conversion and the TOC removal efficiency up to or above 50%. Also, the microwave irradiation could considerably enhance the oxidative degradation of phenol in the UV/H2O2 system even under a suppression of thermal effect. Addition of hydrogen peroxide by more than a stoichiometric amount was critical to mineralize aqueous phenol to create a short reaction time. Also, microwave irradiation can accelerate the degradation rate of intermediates, hydroquinone and catechol, produced in the course of phenol oxidative decomposition. From the kinetic study, the disappearance rate of phenol can be expressed as dX/dt = kPH[M]0(alpha - X)(1 - X), where alpha equivalent [H2O2]0/[M]0 + kOH[OH*]/kPH[M]0, shows a good correlation with the experimental data. The kinetic analysis showed that an indirect reaction of phenol with OH radical might be dominant in the absence of microwave irradiation, meanwhile a direct reaction of phenol with hydrogen peroxide might be dominant in the presence of microwave irradiation except for low concentrations of hydrogen peroxide.     

总拥有费用法优选配电变压器的探讨

总拥有费用法(Total Owning Cost,TOC)用于配电变压器的综合成本计算,不仅考虑了变压器的初始购买费用,还考虑货币的时间价值,把使用期限内的损耗费用折算成等价现值。利用该方法计算出的TOC值越小,则变压器能效越高。以一工程实例,选取型号为S9、S11、SH15的3种变压器进行计算。结果表明,新型的SH15变压器TOC值最小,最高效节能。     

The intensity evaluation of the hydrothermal sedimentation and the relationship with the formation of organic-rich source rocks in the Lower Cambrian Niutitang Formation in Guizhou Province,China

A synthetical study was carried out on the relationship between the hydrothermal sedimentation and the formation of organic-rich source rocks in the Lower Cambrian Niutitang Formation in Guizhou Province, China. Analysis of the high trace elemental contents showed that the V/Sc-V/Cr diagram can be used to distinguish the hydrothermal sediments from normal marine sediments. Cr/Sc ratios can quantitatively evaluate the intensity of hydrothermal sedimentation on account of the positive correlation between the ratios with enrichment factors (EFs) for As, Sb and others. The relationship between Cr/Sc ratios and TOC content illustrated that (1) there was a positive linear correlation between them under the low intensity of hydrothermal activities (Cr/Sc<20), and the enrichment and preservation of organic matters were obviously dominated and potentiated by the hydrothermal sedimentation; (2) The hydrothermal sedimentation was one of the most essential factors influencing the enrichment and preservation of organic matters amidst the medium condition (20< Cr/Sc <300); (3) in the high condition (Cr/Sc > 300), the higher the hydrothermal intensity, the less the enrichment and preservation of organic matters, in other words, it is not conducive to the formation of organic-rich source rocks.