Modeling Approach to Periphyton and Nutrient Interaction in a Stream

We propose a model of the development of a periphyton community in a stream under the influence of nutrients and light. Coupling the model with a nutrient transport model clarified the longitudinal distribution of both periphyton community and nutrients. The thickness of the periphyton mat, an important factor regulating nutrient exchange between the mat and overflowing water, was determined from water velocity and the periphyton biomass. We compared the results of this study with three observational data sets to overall validate our proposal: (1) a comparison of electrical conductance in two channels with different periphyton biomasses validated the model in the mass exchange between stationary and flowing water zones; (2) a comparison of the temporal variation in periphyton biomass and nutrient concentration in a once-through and a re-circulated water channel, validated the relationships among the periphyton biomass, the nutrient uptake rate, and the nutrient concentrations in the stationary water zone; and (3) a longitudinal distribution of the algal species composition of Stigeoclonium and Chamaesiphon, and the nutrient concentrations of a 140 m reach was reproduced and compared with measured data. The light intensity indirectly controlled the nutrient gradients along the stream by the periphyton biomass in the third application.     

Aquifer Response to Sinusoidal or Arbitrary Stage of Semipervious Stream

Analytical expressions for the aquifer responses, viz., groundwater head, rate of flow and cumulative volume of flow, to a generalized sinusoidal stage of semipervious streams considering the stream boundary resistance, are derived. The analytical aquifer responses to a linear stream stage and to a typical analytical flood wave that was used by Cooper and Rorabaugh, are also derived. For a zero-stream resistance, the aquifer responses converge to those for a fully penetrating stream. Also, two analytical methods, a “ramp kernel method” and a “Fourier series method,” for obtaining the aquifer responses to an arbitrary temporal stage of sempervious stream, are developed. The analytical expressions of the ramp kernels for different aquifer responses are developed. The ramp kernel method is found superior to the conventional convolution that uses numerical integration or pulse kernels for obtaining the convolution integral. In the Fourier series method, the aquifer responses to sinusoidal stage are used along with Fourier series. The results obtained using both methods are in close agreement. The new methods are also applicable to fully penetrating streams by assigning a zero value to the stream resistance.     

Image Analyses-Based Nondisruptive Method to Quantify Algal Growth on Concrete Surfaces

A global ban on the use of tributyltin has resulted in the need to screen new antifouling agents to control algal growth in aquatic environments. Standard methods for the quantification of algal biomass are disruptive in nature; therefore, they are not applicable for the screening studies requiring successive observations at specified time intervals. The objective of this study was to develop a nondisruptive method to quantify algal growth on a variety of surfaces. Image analyses and chlorophyll extraction methods were used to quantify an algal biomass on a concrete surface containing different additives. For concrete samples containing single additives, the coefficient of determination between both techniques ranged from 0.74 to 0.84. However, for concrete samples containing multiple additives, the coefficient of determination of both methods ranged from 0.72 to 0.75. Results suggest that an image analyses technique can be used to accurately quantify various types of algae growing on a variety of solid surfaces.     

Confounding Effect of Flow on Estuarine Response to Nitrogen Loading

The total maximum daily load (TMDL) concept provides the basis for regulating pollution load from riverine sources to impaired water bodies. However, load is comprised of two components: flow and concentration. These two components may have confounding, or even conflicting, effects on waterbody attributes of concern. This is particularly the case for dynamic, advective systems, such as estuaries. Resolving these components is critical for properly predicting the response of impaired systems to watershed management actions. The Neuse River Estuary in North Carolina is an example of such an impaired system. Nitrogen has been identified as the pollutant of concern, and the process of developing a TMDL for nitrogen is underway. We, therefore, analyze the extensive data that have been collected for the Neuse River and estuary to investigate spatiotemporal relationships between river flow, riverine total nitrogen (TN) inputs, water temperature, dissolved inorganic nitrogen concentration, algal density, and primary productivity. Results support the belief that phytoplankton in the estuary are under substantial riverine control. However, the riverine TN concentration alone has only a minor role in determining estuarine chlorophyll concentration. River flow has a stronger influence, likely through its effects on down-estuary nitrogen delivery, residence time, salinity, and turbidity. These results imply that using riverine nitrogen load as the metric to evaluate watershed nutrient management may not be appropriate. While nitrogen controls should reduce loads in the long term, in the short term, river flow is the dominant component of load and has the opposite effect of nitrogen on algae at the up-estuary locations.     

Role of Stream Restoration on Improving Benthic Macroinvertebrates and In-Stream Water Quality in an Urban Watershed: Case Study

Many stream restoration projects do not include a requirement for long-term monitoring after the project has been completed, resulting in a lack of information about the success or failure of certain restoration techniques. The National Risk Management Research Laboratory, part of the U.S. EPA Office of Research and Development, evaluated the effectiveness of stream bank and channel restoration as a means of improving in-stream water quality and biological habitat in Accotink Creek, Fairfax City, Va., using discrete sampling and continuous monitoring techniques before and after restoration. This project monitored the effects of a 549 m (1,800 linear-ft) restoration of degraded stream channel in the North Fork of Accotink Creek. Restoration, which was intended to restore the stream channel to a stable condition, thereby reducing stream bank erosion and sediment loads in the stream, included installation of native plant materials along the stream and bioengineering structures to stabilize the stream channel and bank. Results of sampling and monitoring for 2 years after restoration indicated a slight improvement in biological quality for macroinvertebrate indices such as Virginia Stream Condition Index, Hilsenhoff Biotic Index, and Ephemeroptera, Plecoptera, Trichoptera taxa; the differences were statistically significant at 90% level of confidence with the power of greater than 0.8. However, indices were all below the impairment level, indicating poor water quality conditions. No statistically significant differences in chemical constituents and bacteriological indicator organisms were found before and after restoration as well as upstream and downstream of the restoration. The results indicated that stream restoration alone had little effect in improving the conditions of in-stream water quality and biological habitat, though it has lessened further degradation of stream banks in critical areas where the properties were at risk. Control of storm-water flows by placing best management practices in the watershed might reduce and delay discharge to the stream and may ultimately improve habitat and water quality conditions.     

Long-Term Dynamic Modeling Approach to Quantifying Attached Algal Growth and Associated Impacts on Dissolved Oxygen in the Lower Truckee River, Nevada

Nutrient loads enter the lower Truckee River of western Nevada, affecting the growth of attached algae (periphyton) which causes depressed nighttime dissolved oxygen (DO) levels. The lower Truckee River is home to the endangered cui-ui and threatened Lahontan cut-throat trout, with DO standards being established to in part protect these species. Hydrodynamics, nutrient concentrations, periphyton biomass, and DO data spanning August 2000–December 2001 were used to calibrate and verify a modified version of the Water Quality Analysis Simulation Program Version 5 (WASP5). Under typical loading conditions the periphyton community is nitrogen limited, however nitrogen loading from an upstream wastewater treatment facility increased greatly during the analysis period due to approved site construction activities (discharge permit excursion) causing the periphyton community to temporarily become phosphorus limited. The developed modeling approach, with limited calibration, was able to accurately track dynamic system responses. Removing the impact of the noted discharge permit excursion resulted in a minimum computed DO value of 4.13?mg/L, occurring at the downstream end of the modeling domain on August 8, 2001. Additionally removing the impact of all nutrient loads from area agriculture resulted in a predicted minimum DO value of 4.54?mg/L, while also shifting its location significantly upstream and its timing to April 26, 2001. Meeting all prescribed DO standards required establishing a minimum in-stream flow value of 1.81?m3/s (64.0?ft3/s) downstream of Derby Dam.     

Introduction to the Special Section on the International Classification of Functioning, Disability and Health: Implications for Rehabilitation Psychology.

This introduction to the special section of Rehabilitation Psychology on the International Classification of Functioning, Disability and Health (ICF) previews how implications for rehabilitation psychology are explored through 4 articles, each designed to build on the presentation and discussion of the prior piece: an overview of the ICF classification system; a review of contemporary applications of the ICF to clinical, government, and research uses; an update on clinical implementation efforts and related conceptual issues; and a specific application of the ICF to assistive technology service provision. The special section presents the ICF as a compelling development in the classification of functioning and health in health care service provision and, in particular, rehabilitation psychology practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Path Selection in Disaster Response Management Based on Q-learning

Suitable rescue path selection is very important to rescue lives and reduce the loss of disasters,and has been a key issue in the field of disaster response management.In this paper,we present a path selection algorithm based on Q-learning for disaster response applications.We assume that a rescue team is an agent,which is operating in a dynamic and dangerous environment and needs to find a safe and short path in the least time.We first propose a path selection model for disaster response management,and deduce that path selection based on our model is a Markov decision process.Then,we introduce Q-learning and design strategies for action selection and to avoid cyclic path.Finally,experimental results show that our algorithm can find a safe and short path in the dynamic and dangerous environment,which can provide a specific and significant reference for practical management in disaster response applications.     

Response of Building Adjacent to Stiff Excavation Support System in Soft Clay

A three-story school supported by shallow foundations was affected by an adjacent 12.2-m-deep excavation in soft clay in which the excavation support system was a 0.9-m-wide secant pile wall braced by both cross-lot struts and tiebacks. The school is a reinforced concrete frame structure with exterior reinforced concrete foundation walls. This paper summarizes the conditions at the site and presents correlations among construction activities, measured deformations and distortions, and attendant damage in the school. The lateral ground movements associated with the excavation were monitored with four inclinometers placed around the school. The building movements were monitored with optical survey points established on interior columns, exterior walls and on the roof, and with tiltmeters installed on the exterior foundation walls. The damage to the school mainly consisted of 300 to 500-mm-long hairline cracks in nonload bearing walls. Only a few cracks had widths greater than 6 mm. The school deformed such that the portion closest to the excavation sagged and the remainder hogged. Damage was first observed in the area of sagging when angular distortions reached 1/940 and the excavation was approximately 5.5-m deep. Angular distortions as large as 1/300 were observed at the end of the project. The data suggest that angular distortions had to be less than 1/1000 to preclude any damage to the school.     

Human Factors Analysis Classification System Relating to Human Error Awareness Taxonomy in Construction Safety

In several studies it is widely accepted that human error is the main reason for up to 80% of all incidents and accidents in complex high-risk systems that exist in the aviation, petrochemical, healthcare, construction, mining, and nuclear power industries. The construction industry, greatly impacted by accidents, is accountable for more than 1,000 fatalities in each of the past 14 years. The human factors analysis classification system (HFACS) is a general human error framework originally developed and tested as a tool for investigating and analyzing the human causes of accidents with applications to rail, air, and offshore environments. This paper introduces the concept of HFACS along with the framework of human error awareness training (HEAT) and their potential contribution to the construction industry. Based on the HEAT approach, this paper proposes a new error analysis educational and classification tool for safety within the construction industry. The primary difference between HFACS and HEAT is found in the structure, content, and presentation of the information allowing for higher effectiveness in incident investigation and safety education and training in construction.     

基于岩体分级的内蒙古黑牛王矿山支护设计理论研究

内蒙古黑牛王铅锌矿地压显现明显,矿体松散破碎,开采损失贫化大.在采动作用下常出现局部冒落,严重影响了矿山的安全生产.为维护巷道的稳定性,通过对黑牛王铅锌矿的现场工程地质调查,结合室内岩石力学实验,基于Q、RM R、GSI分级对矿区岩体进行质量评价,并通过理论分析,在岩体质量分级结果的基础上提出采用分类支护方法.围岩较稳...     

基于PLC的一种新型小变电所无人值班综合自动化系统

介绍了以S7—226PLC为核心构造的一种新型小变电所无人值班综合自动化系统，详细介绍了整个系统的构造思路以及具体硬件和软件设计方法。     

高炉铁水硅含量自组织预测中的模式量化

研究了高炉铁水硅含量自组织经验进化预测模型中的模式量化问题。在模式量化方案中,采用高炉过程变量时间序列数据的均值、梯度值和波动值作为数据的特征最来进行特征提取,将可预测率、命中率、趋势命中率等判据用于评判预测效果,并用天津铁厂1号高炉的过程数据进行了离线检验。结果表明：基于过程变量的特征提取方法可用于具有均匀时间间隔的高炉过程数据的特征提取。正确运用该方法可使铁水硅含量自组织预测模型的预测命中率提高10％左右。     

基于模糊聚类的模糊神经网络的系统辨识

本文采用基于模糊聚类的模糊神经网络模型对系统进行辨识,首先利用模糊聚类技术来确定系统的模糊空间和模糊规则数,然后利用模糊神经网络来调整模型的前件参数和后件参数。用此设计方法对函数逼近问题进行仿真,结果表明利用聚类技术可以获得较好的初始值,学习速度快、建模精度高。     

晶粒尺寸对Cr-Ni奥氏体不锈钢在硝酸中晶间腐蚀敏感性的影响

通过在含400 mg/L Cr6++40%硝酸溶液中浸没试验和电化学试验,发现随晶粒尺寸的减小,Cr-Ni奥氏体不锈钢晶间腐蚀敏感性随之增加,但当晶粒尺寸小于临界晶粒尺寸时,晶间腐蚀敏感性开始降低。过钝化电位数值与晶粒尺寸无直接关系,与材料本身特性有关,极化后的表面腐蚀形貌与浸没试验结果相一致。     

银山矿业选矿厂再磨沉砂选金试验研究

银山矿业选矿厂二段再磨旋流器流程沉砂中金品位为 13.35g/t,是给矿工序中金品位的 1.35 倍,是溢流工序中金品位的 2.02 倍,金富集效果明显。对二段再磨旋流器流程沉砂直接进行浮选,可获得铜精矿品位 27.55%,铜回收率 54.46%,铜精矿含金 366.31g/t,铜中金回收率 55.33%。研究表明沉砂中存在部分已单体解离铜矿物及单体金,通过提前浮选,可以减少沉砂中细粒级矿物,避免已解离矿物进入立磨机再磨,从而能够实现“能收早收”的目的。     

我国资源约束条件下的经济增长方式与体制转型

我国资源约束严重制约了经济、社会与生态环境的可持续发展，文章在对当前我国资源现状及其利用方式进行分析的基础上，提出必须转变经济增长方式，即从不可持续的经济增长方式如何发展为可持续的经济增长方式，这是我国当前经济增长方式转变的唯一选择，而我国经济增长方式转变不能完全依靠市场机制的基础作用．必须充分发挥政府力量，加快体制转型。     

基于局域网的谦比希铜矿视频监控系统

赞比亚谦比西铜矿是中国在海外建成的第一座,也是迄今为止最大的一座有色金属矿山。目前,赞比亚工业技术相对落后,特别是在信息化技术方面尤为落后。中色非矿作为在海外投资建设的一流矿山企业,为提高矿山安全生产和管理控制水平,建设了基于局域网的全矿视屏监控系统。本文详细介绍了谦比希铜矿视屏监控系统的建设过程,包括网络基础建设、监控点布设、设备选择、系统集成以及使用效果,该系统的建成使用对中色非矿的现代化管理和数字化矿山建设工作起到了极大的促进作用,为矿山的生产、安全、调度等工作提供了支撑平台,同时也为国内外同类矿山视屏监控系统建设提供成功案列。     

基于WebServices的多代理自动协商系统设计

协商系统是人们借助计算机技术和网络技术在internet上实现自动的协商过程。阐述了web services的设计思想、实现框架、功能和特点，并结合具体项目实现了基于web sercics的多代理自动协商系统，从而为企业简化了商品流通环节，提高了交易效率。     

基于DEVICENET的智能MCC在水处理系统的应用

在控制链路中，MCC起着重要的承接作用。向下可为各种用电设备提供动力和控制，向上可与各类基础自动化系统信息互通。传统的MCC通过点对点的硬接线方式来实现与自动化系统信号交接和信息传递；容易造成接线复杂、故障点多、可靠性低的缺点。文章提出了一种基于DEVICENET的智能MCC方案，通过一根电缆即可实现MCC与基础自动化系统间方便的联系。