EQQYAC: Program for determining geothermal reservoir chemical equilibrium

The computer program EQQYAC calculates the equilibrium distribution of inorganic aqueous ion species in geothermal reservoirs, using the chemical composition of discharged fluids and in situ physical measurements. The program, written in FORTRAN IV for a VAX/11-780 computer system, is suited to handle data from wells that produce both steam and liquid phase water. The program has been successfully used with data of wells from Los Azufres geothermal field.EQQYAC estimates the reservoir steam fraction, (excess steam), that could be present in the total discharge fluid. In order to carry out this calculation, the Fischer-Tropsch reaction is assumed to be at equilibrium at reservoir conditions. The deviation of the concentrations of the participant ions from the expected values at equilibrium, are considered due to the excess steam. This program also may be used to study chemical changes in the deep fluid as a consequence of reservoir boiling.     

TOUGHREACT—A simulation program for non-isothermal multiphase reactive geochemical transport in variably saturated geologic media: Applications to geothermal injectivity and CO2 geological sequestration

TOUGHREACT is a numerical simulation program for chemically reactive non-isothermal flows of multiphase fluids in porous and fractured media. The program was written in Fortran 77 and developed by introducing reactive geochemistry into the multiphase fluid and heat flow simulator TOUGH2. A variety of subsurface thermo-physical–chemical processes are considered under a wide range of conditions of pressure, temperature, water saturation, ionic strength, and pH and Eh. Interactions between mineral assemblages and fluids can occur under local equilibrium or kinetic rates. The gas phase can be chemically active. Precipitation and dissolution reactions can change formation porosity and permeability. The program can be applied to many geologic systems and environmental problems, including geothermal systems, diagenetic, and weathering processes, subsurface waste disposal, acid mine drainage remediation, contaminant transport, and groundwater quality. Here we present two examples to illustrate applicability of the program. The first example deals with injectivity effects of mineral scaling in a fractured geothermal reservoir. A major concern in the development of hot dry rock and hot fractured rock reservoirs is achieving and maintaining adequate injectivity, while avoiding the development of preferential short-circuiting flow paths. Rock–fluid interactions and associated mineral dissolution and precipitation effects could have a major impact on the long-term performance of these reservoirs. We used recent European studies as a starting point to explore chemically induced effects of fluid circulation in the geothermal systems. We examine ways in which the chemical composition of reinjected waters can be modified to improve reservoir performance by maintaining or even enhancing injectivity. The second TOUGHREACT application example is related to CO₂ geologic sequestration in a saline aquifer. We performed numerical simulations for a commonly encountered Gulf Coast sediment under CO₂ injection conditions in order to analyze the impact of CO₂ immobilization through carbonate precipitation. Using the data presented in this paper, the CO₂ mineral-trapping capability after 10,000 years can reach 60 kg/m³ of sandstone by secondary carbonate mineral precipitation such as siderite, ankerite, and dawsonite. Most of the simulated mineral alteration pattern is consistent with the field observations of natural CO₂ reservoirs.     

Computer implementation of the constraint method

A computer program based on the constraint method approach to finite elements is described. The program permits the user to select arbitrarily polynomial orders for the various fields to be approximated. A set of nodal variables enforcing C¹ continuity for arbitrary polynomial order is presented, and those aspects of the program algorithm which differ from conventional finite element programs are described, including the numerical determination of a set of independent variables. An example is presented and the results obtained by the constraint method program compared with results from a conventional program. The constraint method approach is seen to be competitive with the conventional approach.     

基于ETM数据的佳木斯市地热预测研究

热红外遥感技术是地热资源调查的有效途径之一。在佳木斯市地热调查研究中,利用ETM热红外波段数据和相应的气象资料,采用单窗算法,反演佳木斯地表温度,分析了地表温度的空间分布特征和热异常状况。研究结果表明,佳木斯市区北东东约30km处存在明显的地表温度异常区,且异常区分布与隐伏断裂构造的分布有较好的对应关系,此区域为寻找地热资源的有利区域。     

Detection of geothermal anomalies using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) thermal infrared images at Bradys Hot Springs, Nevada, USA

Surface temperature anomalies associated with geothermal activity at Bradys Hot Springs, Churchill County, Nevada were mapped using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) thermal infrared (TIR) image data. In order to highlight subsurface contributions of geothermal heat, the ASTER images were processed to minimize temperature variations caused by the diurnal heating effects of the sun. Surface temperature variations caused by changes in albedo were corrected with visible and near-infrared ASTER bands, and a 10-meter-smoothed Digital Elevation Model (DEM) was used to correct for topographic slope effects. Field measurements of ground surface temperatures made over 24-hour periods were used to design a thermal inertia correction incorporating day and night thermal infrared images.In the resulting processed image, background temperature variations were reduced 30-50% without reducing the intensity of geothermal anomalies, thus making it easier to distinguish geothermal activity from ‘false’ anomalies caused by non-thermal springs, topographic effects, and variable rock, soil, and vegetation compositions.     

Qrtzgeotherm: An ActiveX component for the quartz solubility geothermometer

An ActiveX component, QrtzGeotherm, to calculate temperature and vapor fraction in a geothermal reservoir using quartz solubility geothermometry was written in Visual Basic 6.0. Four quartz solubility equations along the liquid–vapor saturation curve: (i) a quadratic equation of 1/T and pressure, (ii) a linear equation relating log SiO₂ to the inverse of absolute temperature (T), (iii) a polynomial of T including logarithmic terms and (iv) temperature as a polynomial of SiO₂ including logarithmic terms are programmed.The QrtzGeotherm has input parameters: (i) HRes—the reservoir enthalpy (kJ/kg), (ii) SiO2TD—silica concentration in total discharge (ppm), (iii) GeoEq—number of quartz solubility equation and (iv) TempGuess—a guess value of the reservoir temperature (°C). The reservoir enthalpy H_res is assumed to be the same as the total discharge enthalpy H_R. The output parameters are (i) TempRes—reservoir temperature (°C) and (ii) VapRes—reservoir vapor fraction.The first step is to calculate the total discharge concentration of silica SiO2TD from the concentration of silica SiO2Col of separated water, sampled after N-separations of vapor and water. To use QrtzGeotherm in MS-Excel, three functions SiO2TD, GeoResTemp and GeoResVap for an N-stage separation of geothermal reservoir fluid are written in Visual Basic for Application (VBA). Similarly, a demonstration program, QrtzGeothrm, is written in Visual Basic 6.0.     

Geotherm: the U.S. geological survey geothermal information system

GEOTHERM is a comprehensive system of public databases and software used to store, locate, and evaluate information on the geology, geochemistry, and hydrology of geothermal systems. Three main databases address the general characteristics of geothermal wells and fields, and the chemical properties of geothermal fluids; the last database is currently the most active. System tasks are divided into four areas: (1) data acquisition and entry, involving data entry via word processors and magnetic tape; (2) quality assurance, including the criteria and standards handbook and front-end data-screening programs; (3) operation, involving database backups and information extraction; and (4) user assistance, preparation of such items as application programs, and a quarterly newsletter. The principal task of GEOTHERM is to provide information and research support for the conduct of national geothermal-resource assessments. The principal users of GEOTHERM are those involved with the Geothermal Research Program of the U.S. Geological Survey. Information in the system is available to the public on request.     

A new numerical procedure to determine the VLE curve

A fast and accurate (to any required precision) numerical method is presented to calculate the vapour-liquid equilibrium for any subcritical temperature from a given equation of state. The calculations are made using the popular program MATHEMATICA, and we think that this method could be very useful in chemical physics and chemical engineering applications, as well as for teaching purposes.     

基于热红外遥感的川藏铁路昌都—林芝段地热异常区定量预测评价研究

识别川藏铁路沿线的地热异常区有助于工程的建设和后期的管理维护。以川藏铁路昌都—林芝段为研究区,基于Landsat 8热红外影像数据,反演地表温度并进行星地同步实验,得到校正后的地温值。围绕地热异常的成因与分布规律,选取地层组合熵、断层缓冲距、断层线密度、地表温度、水系缓冲距、地震动峰值加速度6个影响因子作为地热异常区评价指标并检验因子独立性。构建信息量模型进行定量预测,最终将识别结果划分为5个子区域。研究表明：高异常区和中异常区分别占研究区总面积的9.14%和28.57%,地热高温点的空间分布与地热异常区评价结果基本一致。研究结果可为川藏铁路的设计与施工提供参考依据。     

Geothermal exploration with Hymap hyperspectral data at Brady-Desert Peak, Nevada

We explore the use of Hymap (hyperspectral mapper) to remotely map unique geothermal indicator minerals over the Brady-Desert Peak geothermal fields. Geothermal-related minerals and rocks such as sinter, tufa, and sulfates, display diagnostic characteristics in the visible and shortwave infrared; their presence and distribution can be used to guide more detailed field work for geothermal exploration. The Brady-Desert Peak geothermal fields are located about 80 km east of Reno, Nevada in the Hot Springs Mountains. North-northeast-striking en-echelon faults offset Tertiary volcanic and lacustrine rocks. Two geothermal power plants produce electricity from two separate geothermal systems, one with numerous fumaroles and mudpots, the other showing no active surface expression of geothermal activity. Surface occurrences of gypsum, calcium-carbonate, hematite, and opaline silica were identified at both sites with the hyperspectral data; these minerals when considered together are indicative of geothermal activity at both sites. Mapping results were synthesized with other spatial data in a geographic information systems (GIS) database that was used to help draw structural interpretations of faulting and fault controls at the Brady-Desert Peak area. The same processing methods can be applied to new hyperspectral data sets for future exploration in the Great Basin, especially in areas that lack obvious thermal expressions.     

SQL Server数据库应用程序性能优化方法

为提高基于SQL Server数据库应用程序的执行效率，分析了SQL Server数据库系统自身的查询优化处理技术，总结出多种基于SQL Server数据库的应用程序性能优化方法：选择性能优越的服务器；优化数据库设计；使用查询效率较高的查询语句；使用存储过程；有效的使用事务和批处理；避免阻塞；选择合适的开发工具和采用有效的数据库访问技术。     

Steady state optimization of an ammonia reactor

A hybrid simulation technique for identification and steady state optimization of a tubular reactor used in ammonia synthesis is presented. The parameter identification program finds the catalyst activity factor and certain heat transfer coefficients that minimize the sum of squares of deviation from simulated and actual temperature measurements obtained from an operating plant. The optimization program finds the values of three flows to the reactor to maximize the ammonia yield using the estimated parameter values. Powell's direct method of optimization is used in both cases. The results obtained here are compared with the plant data.     

数字温度传感器DS18B20在化学工业现场温度检测中的应用

针对单总线数字温度传感器DS18B20在读出数据时产生错误,从其操作时序分析了产生读出温度结果错误的原因,并在具体应用中进行了试验,验证了对错误的分析。介绍的DS18B20在单片机系统中对温度检测的原理及程序设计,对化学工业现场温度检测有一定的指导作用。     

A Multiobjective Evolutionary Programming Algorithm and Its Applications to Power Generation Expansion Planning

The generation expansion planning (GEP) problem is defined as the problem of determining WHAT, WHEN, and WHERE new generation units should be installed over a planning horizon to satisfy the expected energy demand. This paper presents a framework to determine the number of new generating units (e.g., conventional steam units, coal units, combined cycle modules, nuclear plants, gas turbines, wind farms, and geothermal and hydro units), power generation capacity for those units, number of new circuits on the network, the voltage phase angle at each node, and the amount of required imported fuel for a single-period generation expansion plan. The resulting mathematical program is a mixed-integer bilinear multiobjective GEP model. The proposed framework includes a multiobjective evolutionary programming algorithm to obtain an approximation of the Pareto front for the multiobjective optimization problem and analytical hierarchy process to select the best alternative. A Mexican power system case study is utilized to illustrate the proposed framework. Results show coherent decisions given the objectives and scenarios considered. Some sensitivity analysis is presented when considering different fuel price scenarios.      

INFOREX-3.0: A database on experimental studies of phase equilibria in igneous rocks and synthetic systems: I. Datafile and management system structure

INFOREX-3.0 is a sophisticated database manager for igneous petrologists and geochemists. It is designed as an aid in searching the published experimental database, and extracting specific subsets of that data. In addition, the program allows the user to derive numerical mineral-melt expressions based on any dataset. Its major function is as a computerized melting-experiment reference manual that presents data in a fixed format, with key word search functions and flags as an integral part of the program. At present, the system accesses information on 162 experimental studies carried out from 1962 to 1994. The database includes 6174 individual runs with more than 8300 coexisting phase compositions for 30 minerals plus melt. Most of the data are “dry”, but about 2200 include volatile components, such as H₂O and CO₂. INFOREX is hot-key driven, allowing users to sort easily and quickly through the data using any set of experimental conditions or rock type parameters. The main options include: (1) configuration of INFOREX; (2) extraction of general information on the current state of the system; (3) updating and editing the database files; (4) selection of run conditions of interest (setting rock types plus a range of pressures, temperatures, oxygen fugacities, run duration as well as types of containers and resultant phase assemblages); (5) setting phase assemblages (e.g., olivine-melt or garnet-spinel) for the selected set of experiments; (6) export/import operations; and (7) calculation of mineralmelt geothermometers. The INFOREX database is a powerful tool for the use in the development of petrogenetic models by providing the ability to manipulate easily accessed mineral-melt equilibria data.     

基于ARM Cortex-M3和Internet的实时数据采集系统设计

设计一种基于ARM Cortex-M3和Internet的实时数据采集系统.系统选用STM32F107VCT6作为核心芯片,通过链接网络芯片DM9161A,配合程序中采用的嵌入式TCP/IP协议栈LwlP,将采集到的区域温度和电压数据实时传送到远程监测端.实验及测试证明,系统运行稳定,数据采集和传送准确,实时性能良好.     

一种基于数据流分析的程序定义域自动确定方法

程序定义域的确定有利于指导测试用例的选取,虽然程序规范规定了输入变量的定义域,但程序实现本身也定义了其定义域,如果二者不能完全重合,那么某些软件故障就可诊断出来,文中提出玫种基于数据流分析的程序定义域自动确定方法,通过对原程序进行数据流分析和相关性分析,求取输入变量的定义域,采用程序抽取的程序定义域自动确定方法,通过对源程序进行数据流分析和相关性分析,求取输入变量的定义域,采用程序抽取技术,将与输入变量无关的语句和函数剔除,简化了源程序,提高了分析效率,采用动态模拟技术,实现了特殊情形下输入变量定义域的确定,实验证明,该方法是行之有效的。     

Analyzing Security Scenarios Using Defence Trees and Answer Set Programming

Defence trees are used to represent attack and defence strategies in security scenarios; the aim in such scenarios is to select the best set of countermeasures that are able to stop all the vulnerabilities.In order to represent preferences among possible countermeasures of a given attack, defence trees are enriched with conditional preferences, obtaining a new structure called CP-defence tree. In this paper we transform a CP-defence tree with preferences among attacks and countermeasures in an Answer Set Optimization (ASO) program. The ASO program, representing the overall scenario, is a special composition of the programs associated to each branch of a CP-defence tree. We describe an implementation that select the best set of countermeasure able to mitigate all the vulnerabilities by computing the optimal answer set of the corresponding ASO program.     

Distance-based and stochastic uncertainty analysis for multi-criteria decision analysis in Excel using Visual Basic for Applications

A program has been developed in Excel and written in Visual Basic for Applications, which enables a decision maker to examine the robustness of a solution obtained when using multi-criteria decision analysis (MCDA). The distance-based and stochastic uncertainty analysis approaches contained in the program allow a decision to be made with confidence that the alternative chosen is the best performing alternative under the range of probable circumstances. The uncertainty analysis methodology overcomes the limitations of existing sensitivity analysis techniques for MCDA by enabling all of the input parameters to be varied simultaneously within their expected ranges. The Weighted Sum Method (WSM) and PROMETHEE are the MCDA techniques available for the user to select in the program. The program is illustrated by applying it to a sustainable water resource development problem in the Northern Adelaide Plains, South Australia.