大空间焊接厂房置换通风效果试验

对某置换通风焊接整体厂房进行了气流组织试验,在正常工况下测试了温湿度、臭氧浓度、室内压强、室内风速、送风风速、回风口风速等数据,并采用发烟法进行了流场显示。发现该厂房采用置换通风方式温湿度分布均匀,臭氧浓度、室内压强、工作区风速均达到设计要求,但测试数据和发烟法试验结果显示,回风效果还有待改善,这与回风管水力失调有关,表明调节对于置换通风厂房的气流组织十分重要。试验结果为大空间厂房置换通风气流组织的研究提供了可靠的数据资料。     

Fenton试剂预处理丁硫克百威废水的实验研究

通过单因素实验考察Fenton试剂预处理丁硫克百威生产废水,研究了反应初始pH值、七水合硫酸亚铁投加量、双氧水投加量和反应时间等因素对废水COD去除率和呋喃酚去除率的影响。结果表明:Fenton法预处理丁硫克百威废水的优化条件是pH=3.0、七水合硫酸亚铁投加量为5.6 g/L、双氧水投加量为25.0 mL/L、反应时间为120 min,在此条件下废水的COD去除率为60.6%,呋喃酚去除率为74.3%,BOD5/COD从0.07上升至0.36,改善了废水水质,保障了后续生化处理条件,为企业废水处理提供了切实可行的理论依据。     

Approximately calibrated small sample inference about means from bivariate normal data with missing values

Frequency properties of approximate Bayesian posterior probability intervals are considered for a small bivariate sample with data missing on one variable. For a class of priors, approximations to the posterior distribution based on matching moments of the t distribution are derived, and compared with the true distributions computed numerically. Coverage properties of highest posterior density intervals for three choices of prior are evaluated by simulation, and compared with other solutions. The simulations suggest that a second moment t approximation combined with the Jeffreys' prior for the bivariate distribution provides intervals that are quite well calibrated, in the sense of having approximate or slightly conservative coverage for a wide range of values of the underlying parameters. The use of calibration to select a suitable reference prior seems to have potential for a large number of problems.     

Conformance checking and diagnosis for declarative business process models in data-aware scenarios

A business process (BP) consists of a set of activities which are performed in coordination in an organizational and technical environment and which jointly realize a business goal. In such context, BP management (BPM) can be seen as supporting BPs using methods, techniques, and software in order to design, enact, control, and analyze operational processes involving humans, organizations, applications, and other sources of information. Since the accurate management of BPs is receiving increasing attention, conformance checking, i.e., verifying whether the observed behavior matches a modelled behavior, is becoming more and more critical. Moreover, declarative languages are more frequently used to provide an increased flexibility. However, whereas there exist solid conformance checking techniques for imperative models, little work has been conducted for declarative models. Furthermore, only control-flow perspective is usually considered although other perspectives (e.g., data) are crucial. In addition, most approaches exclusively check the conformance without providing any related diagnostics. To enhance the accurate management of flexible BPs, this work presents a constraint-based approach for conformance checking over declarative BP models (including both control-flow and data perspectives). In addition, two constraint-based proposals for providing related diagnosis are detailed. To demonstrate both the effectiveness and the efficiency of the proposed approaches, the analysis of different performance measures related to a wide diversified set of test models of varying complexity has been performed.     

Infiltration and wetting of alumina participate preforms by aluminum and aluminum-magnesium alloys

The infiltration and wetting of alumina participates by Al and by Al-Mg alloys was studied through pressure infiltration experiments. In these experiments, a noninvasive capacitance technique was used to determine the infiltration front position as a function of time. An unsaturated slug flow model was used to interpret the infiltration results and determine capillary pressures characteristic of the infiltration process. The characteristic capillary pressures for Al, Al-2Mg, and Al-3Mg at 750 °C and Al-2Mg at 850 °C were not significantly different. Therefore, contrary to usual belief, Mg did not significantly aid the pressure infiltration process. At 750 °C, the maximum values of the contact angle calculated from these capillary pressures were 106 deg for Al and 105 deg for Al-2Mg and Al-3Mg. These contact angle values indicate substantial removal of the oxide layer on the surface of the liquid metal during the infiltration process. The small difference in the contact angles indicates that magnesium had little effect on the wetting of alumina by aluminum. The small effect of Mg on the wetting may be due to absence of reactive wetting at the infiltration speeds present in the experiments and to partial disruption of the oxide layer on the surface of the liquid metal during the infiltration process.     

EGCG-硅胶表面分子印迹聚合物的制备及吸附性能

以γ-氨丙基三乙氧基硅烷修饰的硅胶为载体、表没食子儿茶素没食子酸酯(EGCG)为模板分子、甲基丙烯酸为功能单体,制备了EGCG-硅胶表面分子印迹聚合物(SMIP),考察了溶剂、pH值及温度等因素对SMIP吸附EGCG性能的影响,同时运用Langmuir和Freundlich模型描述平衡状态时SMIP对EGCG的吸附行为...     

膨润土吸附处理甲基嘧啶磷废水的研究

以膨润土作为吸附剂处理甲基嘧啶磷废水,讨论了膨润土的种类、投加量、时间、pH值、温度等对甲基嘧啶磷某工段废水的处理效果的影响。结果表明,钠基膨润土的吸附效果较其它类型的膨润土效果好,其适宜吸附条件为:投加量5%,pH值3,反应温度20℃,搅拌60 min。反应结束后废水中2-二乙基氨基-6-甲基-4-羟基嘧啶的浓度从5 761 mg/L降至130 mg/L以下,COD浓度从12 500 mg/L降至4 233 mg/L以下。     

Parametric models and non-parametric machine learning models for predicting option prices: Empirical comparison study over KOSPI 200 Index options

We investigated the performance of parametric and non-parametric methods concerning the in-sample pricing and out-of-sample prediction performances of index options. Comparisons were performed on the KOSPI 200 Index options from January 2001 to December 2010. To verify the statistical differences between the compared methods, we tested the following null hypothesis: two series of forecasting errors have the same mean-squared value. The experimental study reveals that non-parametric methods significantly outperform parametric methods on both in-sample pricing and out-of-sample pricing. The outperforming non-parametric method is statistically different from the other models, and significantly different from the parametric models. The Gaussian process model delivers the most outstanding performance in forecasting, and also provides the predictive distribution of option prices.     

甘肃梨园河流域SWAT径流模拟与预报

以甘肃梨园河流域为研究对象,收集相关资料组织数据库,建立SWAT分布式流域水文模型,并模拟1990-1999年月地表径流过程。通过比较模拟值与实测值得相对误差Re小于10%,相关系数R2和Nash-Sutcliffe系数Ens均大于0.80,模拟效果较好,认为SWAT模型可适用于梨园河流域的地表径流模拟。而后结合自回归模型和时域法预测的气象数据,加载到已率定的SWAT模型中预测2009-2018年地表径流。结果表明:预测期径流深呈下降趋势,分析径流对气候变化的水文响应,认为径流对气温的水文响应的敏感性较径流对降水的敏感性高。