Upper and Lower Concentration Thresholds for Bulk Organic Substrates in Bioremediation of Acid Mine Drainage

Acidic pit lakes can form in open cut mine voids that extend below the groundwater table. The aim of this research was to determine what bulk organic material concentrations best stimulated sulphate-reducing bacteria (SRB) for acid mine drainage (AMD) treatment within a pit lake. An experiment was carried out to assess the effect of different substrate concentrations of sewage sludge on AMD bioremediation efficiency. Experimental microcosms were made of 300 mm long and 100 mm wide acrylic cores, with a total volume of 1.8 L. Four different concentrations of sewage sludge (ranging from 30 to 120 g/L) were tested. As the sewage sludge concentration increased, the bioremediation efficiency also increased, reflecting the higher organic carbon concentrations. Sewage sludge contributed alkaline materials that directly neutralised the AMD in proportion to the quantity added and therefore played a primary role in stimulating SRB bioremediation. The lowest concentration of sewage sludge (30 g/L) tested proved to be inadequate for effective SRB bioremediation. However, there were no measurable beneficial effects on SRB bioremediation efficiency when sewage sludge was added at concentrations >60 g/L. We compared our results with existing literature data to develop a conceptual model for remediation of AMD in pit lakes through organic material amendments. The model indicated that labile organic carbon availability was more important to the bioremediation rate than AMD strength, so long as iron and sulphate concentrations were not limiting. The conceptual model also indicates that bioremediation may still occur when only low concentrations of organic carbon are present in the pit lakes, albeit at a very slow rate. The model also demonstrates the presence of an organic material amendment threshold where excess organic carbon does not measurably influence the final outcome. The conceptual model defined is well supported by the results of the microcosm experiment.     

Measuring team knowledge: A window to the cognitive underpinnings of team performance.

The authors report an effort aimed at developing and evaluating measures of taskwork and teamwork team knowledge for teams in which members differ in knowledge backgrounds. These measures were used in a study with 36 teams to explore the cognitive underpinnings of team performance variations due to cross-training regime. The authors demonstrate that these measures are valid and provide team performance information that complements outcome and behavioral measures. Teams exposed to full cross-training acquired more taskwork and teamwork knowledge than control teams or teams exposed to a conceptual version of cross-training. Measures of team knowledge provide information regarding team task performance critical for system design and training programs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

采用气化、加氢、发电工艺一体化联产技术提高炼油厂的经济效益

采用气化、加氢、发电工艺一体化联产技术对重油提炼利用，不但节省了大量的投资和操作费用、提高了整个工厂的运行可靠性和效率、降低有害物质的排放，而且提高了炼油装置和油田的灵活性。其中德士古气化工艺把沥青和石油焦副产品转化为洁净的合成气是实现联产工艺的基础。     

Vulnerability of organic acid tolerant wetland biota to the effects of inorganic acidification

Inland waterbodies are often naturally acidic but are these ecosystems pre-adapted to inorganic acidification e.g., by acid sulfate soils (ASS)? We conducted a controlled mesocosm experiment with inorganically acidified wetland water and wetland sediment replicates to pH 3 from a naturally acidic (pH 3.9, conductivity = 74 µS cm^− 1) wetland in south-western Australia. Following acidification, dissolved organic carbon and nitrogen declined, and chlorophyll a dropped to zero. Inorganic acidification mobilised metals from sediment sods with increased water concentrations of Cu, Fe, Mn, Ca, Mg and Al. Acidification showed no significant effect on diatom assemblage. Nonetheless, greatly reduced abundance and diversity of grazing zooplankton was observed. Macroinvertebrates generally showed abundance decreases, although filterer-collector taxa increased. Decreased primary production reduced functional diversity and consumer biomasses. These results suggest likely impact to ecosystem functioning of low pH, weakly-buffered and stained wetlands if exposed to inorganic acidification.     

如何造就未来的工程师——从激光感应线开始

<正>有机会尝试使用实际工程设计工具的学生更有希望将来在工程设计方面有所作为美国教育有一个令人不安的趋势,那就是孩子们不想成为工程师。在即将毕业的高中生中,有兴趣以工程为职业的学生已为数不多。大学电气和计算机工程专业的招生人数不断减少。最令人担忧的是,最近十年来,工     

DistressNet: A disaster response system providing constant availability cloud-like services

Large scale disasters like the earthquake and tsunami in Japan (2011) cripple the local infrastructure. Proprietary systems and protocols used today for disaster response still lack data at the high spatial and temporal resolution needed to quickly save lives and to support disaster recovery efforts. Victims are rescued after days, if not weeks; digital coordination interfaces among responders are lacking, or are based on archaic methods (pencil, paper, paint on walls); the delay in receiving vast amounts of information from the field is bounded by the time used to physically transport tapes or hard drives. In this paper we present the design, implementation and evaluation of DistressNet, a system that provides services for emergency response applications. DistressNet integrates a variety of rapidly deployable, battery powered COTS devices into a secure framework. An optimal placement of networked components allows users to quickly and reliably store and retrieve data, in a “cloud”-like manner, from a local intermittently connected “fog”. High volumes of field data are available for emergency response personnel to view on interfaces like smartphones and tablets. DistressNet is a large academic effort, proposing open systems, instead of proprietary solutions. It has been developed in collaboration with Texas Task Force 1 and its components have been evaluated for over one year in outdoor deployments that required over 1500 man hours.     

Towards the construction of an eigenvalue engine

In this paper a new algorithm for the computation of the eigenvalues of real symmetric matrices is presented. The algorithm may be expressed in terms of a collection of communicating process and is suitable for implementation as a dedicated engine constructed from a network of transputers. However, it can also be efficiently implemented on a multiprocessor supercomputer such as the CRAY X-MP or on a set of interconnected SIMD machines.     

High temporal resolution rainfall–runoff modeling using long-short-term-memory (LSTM) networks

Neural Computing and Applications - Accurate and efficient models for rainfall–runoff (RR) simulations are crucial for flood risk management. Most rainfall models in use today are...