浅析以太网与web技术在铝电解工业控制系统中的应用

阐述了在铝电解工业控制系统中通过采用以太网和web技术进行数据整合的方法,通过节点服务器的架设实现公司内四级网络的物理连通,再使用数据库编程和.NET技术开发应用程序,制作统一的用户界面和综合数据报表,并根据管理人员的需求对数据进行深度挖掘和处理,有效缩短了管理人员获取生产相关数据的时间,为铝电解生产管理人员提供一个便捷、高效、实用的数据分析平台。     

Retrospective Comparison of Watershed Analysis Risk Management Framework and Hydrologic Simulation Program Fortran Applications to Mica Creek Watershed

As part of an ongoing watershed model comparison program for forested watersheds, Watershed Analysis Risk Management Framework (WARMF V5.18) and Hydrologic Simulation Program Fortran (HSPF V10) were independently applied to the Mica Creek Watershed in Idaho. A comprehensive model comparison was made in terms of watershed delineation, hydrologic formulations, model parameterization, meteorological data, hydrologic calibration, and hydrologic verification. Comparison was not made for water quality, which was not simulated in the HSPF application. It was concluded that WARMF is a mechanistic model structured to simulate the hydrologic processes, whereas HSPF is an empirical water budget model. The WARMF is suitable for application to forested watersheds. It successfully predicted stream flows comparable to measured values. The HSPF results were also good, if one ignores an unrealistic amount of water loss to inactive groundwater and an empirical treatment of rain-on-snow events.     

Development of an Empirical Lag Time Equation

A regression analysis was performed on measured lag times from gauged watersheds to develop a lag time equation. The watersheds are part of the Agricultural Research Service’s database. They are located in several states and are comprised of varying terrain. The goal of the analysis was to develop a lag time equation that is useful in hydrologic modeling. The study included measurements from approximately 10,000 direct runoff events from 52 watersheds to determine which watershed parameters are best for predicting lag time. The lag time was found to correlate strongly with the longest hydraulic length of the watershed. Therefore an equation was developed that used only this parameter. The inclusion of any other watershed characteristics in the equation did not improve its ability to predict the lag time. Finally, the National Resource Conservation Service procedures for calculating watershed lag time were used to determine the lag times of the watersheds. These estimated lag times were then compared with the measured lag time of the watershed. It was found that the use of these methods generally underpredicted the true lag time of a watershed.     

Hydrologic and Water Quality Integration Tool: HydroWAMIT

A spatially distributed and continuous hydrologic model focusing on total maximum daily load (TMDL) projects was developed. Hydrologic models frequently used for TMDLs such as the hydrologic simulation program—FORTRAN (HSPF), soil and water assessment tool (SWAT), and generalized watershed loading function (GWLF) differ considerably in terms of spatial resolution, simulated processes, and linkage flexibility to external water quality models. The requirement of using an external water quality model for simulating specific processes is not uncommon. In addition, the scale of the watershed and water quality modeling, and the need for a robust and cost-effective modeling framework justify the development of alternative watershed modeling tools for TMDLs. The hydrologic and water quality integration tool (HydroWAMIT) is a spatially distributed and continuous time model that incorporates some of the features of GWLF and HSPF to provide a robust modeling structure for TMDL projects. HydroWAMIT operates within the WAMIT structure, developed by Omni Environmental LLC for the Passaic River TMDL in N. J. HydroWAMIT is divided into some basic components: the hydrologic component, responsible for the simulation of surface flow and baseflow from subwatersheds; the nonpoint-source (NPS) component, responsible for the calculation of the subwatershed NPS loads; and the linkage component, responsible for linking the flows and loads from HydroWAMIT to the water quality analysis simulation program (WASP). HydroWAMIT operates with the diffusion analogy flow model for flow routing. HydroWAMIT provides surface runoff, baseflow and associated loads as outputs for a daily timestep, and is relatively easy to calibrate compared to hydrologic models like HSPF. HydroWAMIT assumes that the soil profile is divided into saturated and unsaturated layers. The water available in the unsaturated layer directly affects the surface runoff from pervious areas. Surface runoff from impervious areas is calculated separately according to precipitation and the impervious fractions of the watershed. Baseflow is given by a linear function of the available water in the saturated zone. The utility of HydroWAMIT is illustrated for the North Branch and South Branch Raritan River Watershed (NSBRW) in New Jersey. The model was calibrated, validated, and linked to the WASP. The NPS component was tested for total dissolved solids. Available weather data and point-source discharges were used to prepare the meteorological and flow inputs for the model. Digital land use, soil type datasets, and digital elevation models were used for determining input data parameters and model segmentation. HydroWAMIT was successfully calibrated and validated for monthly and daily flows for the NSBRW outlet. The model statistics obtained using HydroWAMIT are comparable with statistics of HSPF and SWAT applications for medium and large drainage areas. The results show that HydroWAMIT is a feasible alternative to HSPF and SWAT, especially for large-scale TMDLs that require particular processes for water quality simulation and minor hydrologic model calibration effort.     

Stochastic Streamflow Simulation Using SAMS-2003

SAMS is a specialized software that has been developed for analyzing, modeling, and generating synthetic samples of hydrologic and water resources time series such as monthly streamflows. The 2003 version of SAMS provides enhanced technical capabilities from the earlier versions of the software. The graphical user interface and the mechanisms for handling the data have been entirely rewritten in MS Visual C++. As a result SAMS-2003 is easier to use and easier to update and maintain. In addition, substantial changes and restructuring have been made to enhance the modeling and data generation capabilities. The package provides many menu option windows that focus on three primary application modules—statistical analysis of data, fitting of a stochastic model (including parameter estimation and testing), and generating synthetic series. SAMS has the capability of analyzing and modeling single site and multisite annual and seasonal data such as monthly and weekly streamflows based on a number of single site and multisite stochastic models, and aggregation and disaggregation modeling schemes. The models are then utilized for generating synthetic data. Results from the various computations, e.g., the generated samples, can be presented in graphical and tabular forms and, if desired, saved to an output file. Some illustrations are provided to demonstrate the improved technical capabilities of the program using flow data of the Colorado River system.     

Event and Continuous Hydrologic Modeling with HEC-HMS

Event hydrologic modeling reveals how a basin responds to an individual rainfall event (e.g., quantity of surface runoff, peak, timing of the peak, detention). In contrast, continuous hydrologic modeling synthesizes hydrologic processes and phenomena (i.e., synthetic responses of the basin to a number of rain events and their cumulative effects) over a longer time period that includes both wet and dry conditions. Thus, fine-scale event hydrologic modeling is particularly useful for understanding detailed hydrologic processes and identifying the relevant parameters that can be further used for coarse-scale continuous modeling, especially when long-term intensive monitoring data are not available or the data are incomplete. Joint event and continuous hydrologic modeling with the Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS) is discussed in this technical note and an application to the Mona Lake watershed in west Michigan is presented. Specifically, four rainfall events were selected for calibrating/verifying the event model and identifying model parameters. The calibrated parameters were then used in the continuous hydrologic model. The Soil Conservation Service curve number and soil moisture accounting methods in HEC-HMS were used for simulating surface runoff in the event and continuous models, respectively, and the relationship between the two rainfall-runoff models was analyzed. The simulations provided hydrologic details about quantity, variability, and sources of runoff in the watershed. The model output suggests that the fine-scale (5?min time step) event hydrologic modeling, supported by intensive field data, is useful for improving the coarse-scale (hourly time step) continuous modeling by providing more accurate and well-calibrated parameters.     

Evaluating Watershed Experiments through Recursive Residual Analysis

The question of watershed response to changes in land use and land cover has received a great deal of attention in the hydrologic literature. One of the primary tools for quantifying such changes has been the paired watershed approach. In general this approach applies a linear regression analysis to relate water yield from a control watershed to a physiographically similar watershed in close proximity, and to predict changes in yield following treatment. Although much research on paired watershed experiments has focused on quantification of the impacts of land-use and land cover changes on water yield, little attention has been brought to evaluating explicitly the methodology used to quantify such effects. An alternative method is proposed for examining treatment impacts and their duration, through the application of a cumulative recursive residual test of model stability. The results from a paired watershed study of ponderosa pine watersheds in north-central Arizona are analyzed using both a traditional linear regression analysis and a recursive residuals approach. The results suggest that the linear regression approach may fail to account for the true complexity of watershed response to vegetation treatments, by underestimating the interactions of treatment impacts, shifts in climatic drivers, and revegetation rates.     

Intelligent Medical Record--entry (IMR-E)

This paper describes an automated medical record designed to allow providers to enter patient data at the point of care. The system runs on PCs and Macintoshes and uses a graphical user interface and object-oriented programming to take advantage of current mouse and pen technologies. The provider acquires all relevant patient data by pointing and clicking at selections on input screens, many of which contain anatomical drawings to help the provider quickly and accurately describe patient findings. The system also generates a grammatically correct progress note using the problem-oriented structure. Furthermore, items identified in the assessment and plans portion of the program can be ported to expert systems for medical decisions assistance or to billing systems. The system allows the provider to obtain the necessary information on a focused patient visit in less than 5 min or to enter a complete history and physical.     

基于C/S与B/S混合模式的WebGIS模型设计

介绍了网络地理信息系统(WebGIS)的发展概况,在分析已有WebGIS模型存在问题的基础上,提出了一种基于C/S与B/S混合模式的WebGIS模型。该模型采用三层次结构,分为用户交互层、应用服务层和数据服务层。在交互层中采用了分离管理用户和一般用户的方法,减少了服务器端负荷和网络负载,加快了用户访问、查询速度,而且提高了模型的安全性。该模型可以使用多种不同的数据源,模型也具有开放性、可扩充性、高内聚、低耦合等优点。     

Integrated Hydrologic Modeling and GIS in Water Resources Management

The integration of a physically-based distributed model with a geographic information system (GIS) in watershed-based water resources management is presented, and an example watershed is chosen to demonstrate the spatial database and modeling system developed in this study. The spatial data is first processed by GIS. The model is then used to simulate runoff hydrographs. It operates at a daily time step on 1 × 1 km grid squares and simulates important hydrologic processes including evapotranspiration, snowmelt, infiltration, aquifer recharge, ground-water flow, and overland and channel runoff. Finally, the model result is displayed by using GIS. This study demonstrates that the integration of a physically based distributed model and GIS may successfully and efficiently implement the watershed-based water resources management. Not only does this process facilitate examination of a wider range of alternatives that would be impossible by using conventional methods, but it also provides a living management that could be modified and updated by water managers once the watershed condition is changed.     

Searching for information on the World Wide Web--a guide for dental health professionals: Part 1

Mastering the retrieval of valid information from the Internet can be challenging, especially for busy professionals with little time for learning the necessary techniques. This article provides a conceptual framework for browsing and searching for clinically relevant, valid information on the Web. Part 1 provides an overview of the Web that includes information on access methods, general characteristics, and the main user interface (a browser). Concerns about information validity are also discussed. Part 2 will describe several common methods for searching the Web, including how to visit a web site directly, visit a directory site, and conduct a search via a search-engine site.     

Integrated Reservoir-Based Canal Irrigation Model. I: Description

The success of irrigation system operation and planning depends on the quantification of supply and demand and equitable distribution of supply to meet the demand if possible, or to minimize the gap between the supply and demand. Most of the irrigation literature mainly focuses on the demand and distribution aspects only. In addition, irrigation projects that receive water from a reservoir can be challenging to manage as annual fluctuations in runoff from the reservoir’s catchment can have considerable impact on the irrigation management strategy. This study focuses on the development of an integrated reservoir-based canal irrigation model (IRCIM) that includes catchment hydrologic modeling, reservoir water balance, command hydrologic modeling, and a rotational canal irrigation management system. The front end of the IRCIM is developed in Visual Basic 6.0, whereas the back-end coding is done in C language. The graphical user interface is the most important feature of the model, as it provides a better interaction between the model and its user. The IRCIM has a modular structure that consists of three modules, viz., catchment module, reservoir module, and crop water demand module. The catchment module predicts daily runoff from the catchment that inflows to the reservoir. Depending on the data availability, this module is provided with the flexibility of choosing between the Soil Conservation Service’s curve number method combined with the Muskingum routing technique, and an artificial neural network technique using the Levenberg–Marquardt algorithm. The reservoir module is based on conservation of mass approach, and results in daily reservoir storage. The crop water demand module is comprised of water-balance models for both paddy and field crops. The irrigation management system serves as the program flow controller for the model and runs the required module when needed. For postseason evaluation of the irrigation system, performance indicators such as adequacy, efficiency, equity, and dependability are used. In a companion paper, the model is applied for Kangsabati Irrigation Project, West Bengal, India.     

Variations of Time of Concentration Estimates Using NRCS Velocity Method

Time of concentration (Tc) is the time required for runoff to travel from the hydraulically most distant point to the outlet of a watershed. The Natural Resources Conservation Service (NRCS) velocity method commonly is used to estimate Tc for hydrologic analysis and design. The NRCS velocity method applies the physical concept that travel time is a function of runoff flow length and flow velocity. Time of concentration for 96 Texas watersheds is independently estimated by three research teams using the NRCS velocity method. Drainage areas of the 96 watersheds considered in the study are approximately 0.8–440.3?km2 (0.3–170?mi2). Digital elevation models having a grid size of 30?m were used to derive watershed physical characteristics using ArcGIS or HEC-GeoHMS. Average channel width was estimated from 1?m or 1?ft digital orthoimagery quarter quadrangle or aerial photography. Each team made independent decisions to estimate parameters needed for different flow segments for the NRCS velocity method. Estimates of time of concentration made by three research teams are compared, and both graphic comparison and statistical summary demonstrate that time of concentration estimated using the NRCS velocity method is subject to large variation, dependent on the analyst-derived parameters used to estimate flow velocity. Because of the propensity for different analysts to arrive at different results, caution is required in application of the NRCS velocity method to estimate Tc.     

Evaluating Internet end-to-end performance: overview of test methodology and results

OBJECTIVE: An evaluation of Internet end-to-end performance was conducted for the purpose of better understanding the overall performance of Internet pathways typical of those used to access information in National Library of Medicine (NLM) databases and, by extension, other Internet-based biomedical information resources. DESIGN: The evaluation used a three-level test strategy: 1) user testing to collect empirical data on internet performance as perceived by users when accessing NLM Web-based databases, 2) technical testing to analyze the Internet paths between the NLM and the user's desktop computer terminal, and 3) technical testing between the NLM and the World Wide Web ("Web") server computer at the user's institution to help characterize the relative performance of Internet pathways. MEASUREMENTS: Time to download the front pages of NLM Web sites and conduct standardized searches of NLM databases, data transmission capacity between NLM and remote locations (known as the bulk transfer capacity [BTC]), "ping" round-trip time as an indication of the latency of the network pathways, and the network routing of the data transmissions (number and sequencing of hops). RESULTS: Based on 347 user tests spread over 16 locations, the median time per location to download the main NLM home page ranged from 2 to 59 seconds, and 1 to 24 seconds for the other NLM Web sites tested. The median time to conduct standardized searches and get search results ranged from 2 to 14 seconds for PubMed and 4 to 18 seconds for Internet Grateful Med. The overall problem rate was about 1 percent; that is, on the average, users experienced a problem once every 100 test measurements. The user terminal tests at five locations and Web host tests at 13 locations provided profiles of BTC, RTT, and network routing for both dial-up and fixed Internet connections. CONCLUSION: The evaluation framework provided a profile of typical Internet performance and insights into network performance and time-of-day/day-of-week variability. This profile should serve as a frame of reference to help identify and diagnose connectivity problems and should contribute to the evolving concept of Internet quality of service.     

Retrofit Storm Water Retention Volume for Low Impact Development

The concept of low impact development (LID) applies decentralized on-site runoff source control to storm water management. LID is an integration of bioretention and vegetated landscapes to maintain a catchment’s hydrologic and ecological functions. In current practice, the LID implementation is quantified for the specified watershed development. During the dynamic development process, the existing LID facilities have to be improved according to the incremental changes in the watershed. This technical note presents an on-site hydrologic approach to relate the required incremental storm water retention volume to the alteration of surface imperviousness in the tributary area. This approach allows the storm water retention volume to be tailored according to the stage of the watershed development. Cumulatively, the total storage volume can be achieved though multiple stages of the watershed development. The incremental retention volume is found to be related to the local average event rainfall depth. Design charts were produced and normalized by the local average rainfall event depth for generalized applicability.     

RNA secondary structure as a reusable interface to biological information resources

The dissemination of biological information has become critically dependent on the Internet and World Wide Web (WWW), which enable distributed access to information in a platform independent manner. The mode of interaction between biologists and on-line information resources, however, has been mostly limited to simple interface technologies such has hypertext links, tables and forms. The introduction of platform-independent runtime environments facilitates the development of more sophisticated WWW-based user interfaces. Until recently, most such interfaces have been tightly coupled to the underlying computation engines, and not separated as reusable components. We believe that many subdisciplines of biology have intuitive and familiar graphical representations of knowledge that can serve as multipurpose user interface elements. We call such graphical idioms "domain graphics". In order to illustrate the power of such graphics, we have built a reusable interface based on the standard two dimensional (2D) layout of RNA secondary structure. The interface can be used to represent any pre-computed layout of RNA, and takes as a parameters the sets of actions to be performed as a user interacts with the interface. It can provide to any associated application program information about the base, helix, or subsequence selected by the user. We show the versatility of this interface by using it as a special purpose interface to BLAST, Medline and the RNA MFOLD search/compute engines. These demonstrations are available at: http://www-smi.stanford.edu/projects/helix/pubs/ gene-combis-96/     

Application of Web Services for Structural Engineering Systems

The Internet has revolutionized the way computing is done and the way software systems work. Many systems, such as search engines and PC games, have utilized Web-related technologies for Web-based systems. However, the application of Web-based engineering software is still in its infancy, especially regarding engineering computing. This paper presents a prototype development of Web-based structural engineering systems by utilizing modern computer graphics and information technology to provide Web-based analytical services. The system design emphasizes platform-independence, graphical interface, system performance, and a multiple-user environment. The user needs only an Internet-connected machine to access high-performance services provided at remote sites over the Web. This framework will provide users a powerful tool to efficiently perform analysis with minimal computer resource requirements. The user will always have access to the most up-to-date and functional system with no client-side updates or maintenance required. Two Web-based system implementations are given as examples in this paper.