共查询到20条相似文献,搜索用时 15 毫秒
1.
在提出对电解铝厂进行环境风险评价的必要性基础上,浅谈对电解铝厂环境风险评价思路的总体认识,辨析电解铝厂的环境风险,同时提出当前在编制电解铝厂环境风险评价中存在的主要问题,以期共同探讨如何编写好电解铝厂环境风险评价专章,确实让环境风险评价在环保管理及决策部门对建设项目实施环境管理的工作中发挥作用. 相似文献
2.
针对MAG焊焊缝跟踪过程中存在的焊缝偏差问题,建立基于粗糙集原理的窄间隙MAG焊焊缝偏差分析数学模型。偏差数学模型由数据采集、决策准则、数据预处理和模型简化四部分组成。基于数学模型的焊缝偏差分析不仅可以充分挖掘模型本身的信息,还具有直观性强和易于理解等优点。结果表明,利用所建立的数学模型能够有效地预测焊缝偏差,且具有较高的焊接定位精度。本研究对于焊缝偏差的识别和预测具有一定的指导意义,同时也为电弧控制器的设计提供了重要参考依据。 相似文献
3.
信息网络安全对于互联网办公来说具有十分重要的意义。实时网络安全风险评估作为信息安全的一个关键组成要素,能够对网络资源的安全状态进行有效检测。因此,为了提高互联网环境中办公资源的安全性,提出了一种基于预测模型的网络安全风险在线评估方法。该方法使用期望最大化(expectation and maximization,EM)算法对传统连续时间隐Markov模型进行了改进,以便完成基于预测模型的风险评估。仿真实验结果显示:提出方法能够有效地完成网络安全在线预测。相比其它方法提出方法能够实现较高的准确率和实时性,能够满足互联网环境下的各种信息安全需求。 相似文献
4.
For the unidirectional solidification in a mold cooled by air or water, several mathematical models have been proposed. However,
some are complex series solutions, and some are good approximations only when solidification time is sufficiently small. Therefore,
our research team proposes the present mathematical model, which is a good approximation when solidification time is sufficiently
large. In order to estimate the convergency characteristics of the present model, numerical solutions were calculated with
mold/solid heat transfer coefficients, which are experimentally determined by a previous and the present model. 相似文献
5.
A mass transfer mathematical model was developed based on one-side plate steady-state ultrafiltration (UF), and the numerical solution was obtained by Crank-Nicolson finite difference method. The effects of the feed concentration, channel length, axial velocity, and diffusion coefficient on the concentration at membrane surface and the concentration profiles were investigated. Furthermore, the operation parameters and the parameters of membrane module were all transfonaaed into dimensionless ones, and the parameter rejection was included in the mass transfer model, therefore, it can be used to calculate the steady-state ultrafiltration with different rejections. The model was used for the calculation of the ultrafiltration of metal-cutting oil emulsion. The results show that the concentration polarization can be reduced by increasing the axial velocity to some extent, but the reduction of concentration polarization is very small when the resistance of ultrafiltration is very great. 相似文献
6.
介绍了数控加工宏程序及其特点,通过椭圆曲线、抛物线、双曲线、渐开线这些二次非圆曲线的宏程序编写,将数学知识(特别是利用解析几何中的标准方程、参数方程及极坐标方程表达式)与计算机编程语言相结合,分析比较手工编程与自动编程的各自特点,编写出更好的数控加工程序。 相似文献
7.
8.
Mohammed Taleb-Berrouane Kelly Hawboldt Richard Eckert Torben Lund Skovhus 《腐蚀工程科学与技术》2018,53(5):378-392
Corrosion is one of the major causes of failure in onshore and offshore oil and gas operations. Microbiologically influenced corrosion (MIC) is inherently more complex to predict, detect and measure because, for instance, the presence of biofilm and/or bacterial products is not sufficient to indicate active microbiological corrosion. The major challenge for current MIC models is to correlate factors that influence corrosion (i.e. chemical, physical, biological and molecular variables) with the potential of having MIC. Previous work has proposed the potential for MIC as a simple product of multiple factors, without fully considering the synergy or the interference among the factors. The present work proposes a network-based approach to analyse and predict MIC potential considering the complex interactions among a total of 60 influencing factors and 20 screening parameters. The proposed model has the ability to capture the complex interdependences and the synergic interactions of the factors used to assess MIC potential and uses an object-oriented approach based on a Bayesian Network. The model has been tested and verified using real data from a pipeline leakage incident that was a result of MIC. The proposed model constitutes a significant step in deepening the understanding of when MIC occurs and its predictability.
List of acronyms: APB: acid producing bacteria; Aw: water activity; BN: Bayesian network; MIC: microbiologically influenced corrosion; MMMs: molecular microbiological methods; NRB: nitrate-reducing bacteria; OOBN: object-oriented Bayesian network; PWRI: produced water re-injection; SPs: screening parameters; SRB: sulphate-reducing bacteria; SRPs: sulphate-reducing prokaryotes; TDSs: total dissolved solids 相似文献
9.
用Gleeble-3500热模拟试验机对SA533B核电压力容器用钢进行热压缩试验,研究不同热变形条件下SA533B钢的高温变形抗力,分析了变形温度、变形速率及变形量与变形抗力之间的关系,利用回归分析确立合适的变形抗力数学模型。结果表明,变形温度对变形抗力影响较大,变形速率较低时变形抗力变化较大,变形量对变形抗力的影响主要在变形初期。变形抗力数学模型为: σ=4311.322584×ε0.098ε’ 0.0874exp(-0.0034T+0.2813ε) 相似文献
10.
The experiments of metal Cd extraction were carried out three times at oil phase/aqueous phase (O/A)=1 and pH 2.2 by using 1.3 mol/L di(2-ethylhexyl)phosphoric acid (DEHPA) as the agent,with an extraction rate of 99.5%.Experiments on metal Co extraction were done three times at O/A=0.5 and pH 4.7 by using 0.4 mol/L Cyanex 272 as the agent,with an extraction rate of 99.2%.By using equilibrium data and massive calculations to analyze and predict the interaction among the extraction systems,this paper came out with the polynomials of the empirical model as well as their parameter values for the equilibrium concentration of the above two extraction loops. 相似文献
11.
Ger-Chwang Wang Kuang-Hwa Fuh Biing-Hwa Yan 《International Journal of Machine Tools and Manufacture》2001,41(1):103-132
A new mathematical model for multifacet drills (MFD) is developed using angle-solid-block approach to find the relationship of design parameters. The function of chisel edge angle is defined as ψ=f(ρ′ ,τ ,αr) in order that the uncertainty of chisel edge geometry determined by existed model can be avoided. The effects of the new mathematical model on the geometry of chisel edge and main cutting edge are shown in this paper. In addition, the new mathematical model has the potential of designing and researching for many tools. 相似文献
12.
Prediction of time from corrosion initiation to corrosion cracking is a crucial factor in evaluating concrete structures' durability and integrity deteriorated by reinforcement corrosion. This paper presents a mathematical model to predict the time from corrosion initiation to corrosion cracking. A dynamic corrosion rate model based on Bulter–Volmer kinetics and a rust expansion model based on Faraday's law are developed. An analytical model is developed to demonstrate the mechanical consequences of rust buildup around the rebar. The time to corrosion cracking is found to be a function of surrounding concrete material properties, chemical composition of rust, ratio of concrete cover thickness to rebar diameter, and corrosion current density. Comparisons with available experimental results are conducted to show the accuracy and reliability of the present model. Further parametric analysis is carried out to show the influences of various parameters included in the model on the time to corrosion cracking. 相似文献
13.
A novel method to prepare soil nutrient amendment by calcining a mixture of white mud and potassium feldspar and its environmental assessment were investigated. Under the optimal conditions of a blending mass ratio of 70:30 for white mud to potassium feldspar, a calcination temperature of 1 000 °C, a calcination time of 1.5 h and spherulitic diameter of 2.0 cm, the calcined product, as a soil nutrient amendment, could be prepared with the following nutrient composition (mass fraction): K2O 4.16%, CaO 23.43%, MgO 5.04%, SiO2 22.92%, SO42− 3.71%, and Cl− 3.87% in 0.1 mol/L citric acid solution. The concentrations of heavy metals in the calcined product and the emission concentrations of harmful gases from a mixture of white mud and potassium feldspar during calcination process could qualify the National Standards without causing secondary environmental pollution. 相似文献
14.
15.
Weizhen OUYANG ) Xia CAO ) Ning WANG ) ) Guilin Air Force Academy Guilin China ) Beijing University of Aeronautics Astronautics Beijing China 《金属学报(英文版)》2009,22(2):91-99
The aim of this article was to theoretically study diffusion and migration of chlo-ride ions during electrochemical chloride removal. The proposed model would enable optimization of its application by predicting the optimal treatment time and current combination. A mathematical model for simulating the transport behavior of chloride ions was developed by consideration of diffusion and migration of chloride ions when a constant DC current density was applied through the marine cast iron artifacts. The corresponding tests were conducted to validate the mathematical model. This model predicted the data of the extraction ratio of the chloride ion that correlated satisfac-torily with the experimental values. An important issue in electrochemical chloride removal was to understand how chloride ions moved, taking account of diffusion and migration of chloride ions and the release of binding chloride ions. The effects of the treatment time, externally applied current density, chloride diffusion coefficient, and rate constant of release of binding chloride ion on chloride removal are studied. The specific quantitative details applied to one-dimensional model were discussed here. This article has proposed a mathematical model for the first time, which was showed to be a useful tool that can reveal the ionic transport mechanism and optimize the application during electrochemical chloride removal. 相似文献
16.
制造执行系统在生产管理信息系统与设备控制系统之间构筑了一座桥梁,连接了企业上层管理与下层控制之间的信息断层。为了提高制造执行系统的整体执行性能,需要对各单元的生产业绩进行分析与评价。提出了分析与评价指标体系并重点阐述了改进的层次分析法及基于模糊重心和模糊重心矩的综合评价理论在制造执行系统业绩分析与评价中的应用。 相似文献
17.
18.
H. Fukanuma 《Journal of Thermal Spray Technology》1994,3(1):33-44
Thermal spray coatings have porosity; however, reasons for the production of porosity during the coating process are not known.
This paper proposes a physical and mathematical model for the production of porosity by considering deformation of a molten
particle during thermal spray coating processes. The theoretical model shows that the impinging velocity, the ambient gas
pressure, the particle diameter, and the molten material viscosity contribute to producing porosity. This paper also proposes
that there is a porosity distribution along the splat radius and that most of the porosity exists in the periphery of the
splat. Also, a flattening model proposed in this work agrees well with the results of Engel (Ref 1). 相似文献
19.
采用生命周期评价方法对锌冶炼过程中的两种污酸处置工艺进行评价和对比。结果表明,气液硫化法的环境影响主要为人体毒性、非生物资源耗竭和全球变暖潜值,这些环境问题主要由中和-蒸发-结晶与电渗析单元造成;同时传统石灰石中和法中的硫化单元也是环境影响的主要来源,且石灰石中和法的总环境影响比气液硫化法高很多。结合敏感性分析发现,气液硫化法和石灰石中和法敏感度因子均为电和硫化钠(60%),且石灰石中和法处置单位污酸的总成本约为气液硫化法的27倍。 相似文献
20.
考虑到液压马达滑靴副尺寸误差和圆弧面等因素的影响,本文建立了比目前模型更为准确的新的滑鞭副模型。通过比较,指出原来模型的不足之处,并研究了结构参数与静压支承滑靴刚性能之间的关系。 相似文献