食品检测中生物技术的有效运用

在食品科学技术发展与对外贸易不断扩大的背景下,食品检测与分析工作在保证食品安全中的地位越来越高。面对日渐严苛的食品检测要求,以生物技术取代传统分析方法是一种趋势,比如DNA探针技术、PCR技术和免疫学技术等。     

用氯仿萃取处理高浓度含酚废水的实验研究

用氯仿对含酚废水进行了萃取及反萃取实验，并研究了回收氯仿对废水萃取处理的效果以及多级萃取对萃取率的影响，得到的最佳萃取条件为：时间为20 min；废水与氯仿比例为1∶1；pH值为6，温度为室温（20℃左右）。此时萃取率为83.68%，氯仿的回收率为95%左右，通过三级萃取实验得到总的萃取率为95.54%。     

二道岭矿区天荣井田煤层气地面抽采利用可行性探讨

文章论述了天荣井田内的煤层气赋存条件、赋存特征及我国煤层气利用现状,结合国内煤层气利用典型企业的先进技术特点,分析了天荣井田煤层气地面抽采技术和综合利用的可行性。     

Air passenger duties as strategic tourism taxation

There has been a recent debate on the rationale and economic impacts of air passenger duties (APDs) linked to puzzling empirical results on this topic. We argue that an approach from strategic tourism taxation can improve our understanding of these results. APD set by origin countries of tourists can be viewed as an instrument for extracting economic rents that would otherwise be retained by tourism destinations. A theoretical model of strategic taxation between an origin and two destinations is developed to illustrate this idea. We find that countries' strategies may end up with winners and losers, or with all parties facing welfare losses. The game outcome depends on countries' market shares of profits and the substitutability between tourism services provided by different destinations. The findings suggest that the economic impacts of APDs recently evaluated in the literature might be biased because of the omission of other countries' potential tax reactions.     

Hypothetical extractions from a global perspective

ABSTRACT

The hypothetical extraction method (HEM) has been widely used to measure interindustry linkages and the importance of industries. HEM considers the hypothetical situation in which a certain industry is no longer operational. HEM was developed for national economies, using national input–output tables. When performing HEM, it is assumed (often implicitly) that the input requirements that were originally provided by the extracted industry are met by additional imports in the post-extraction situation. Applying HEM to global multiregional input–output tables then causes serious problems. It is no longer sufficient to assume that the required inputs are imported. Instead, it is necessary to indicate explicitly how much is imported from each origin to replace the original inputs. Our adaptation of HEM is the global extraction method (GEM). As an illustration, GEM is applied to the extraction of the motor vehicle industry in China, the US, and Germany, using the 2014 WIOD input–output table.     

Forecasting tourism demand with denoised neural networks

The automated Neural Network Autoregressive (NNAR) algorithm from the forecast package in R generates sub-optimal forecasts when faced with seasonal tourism demand data. We propose denoising as a means of improving the accuracy of NNAR forecasts via an application into forecasting monthly tourism demand for ten European countries. Initially, we fit NNAR models on both raw and denoised (with Singular Spectrum Analysis) tourism demand series, generate forecasts and compare the results. Thereafter, the denoised NNAR forecasts are also compared with parametric and nonparametric benchmark forecasting models. Contrary to the deseasonalising hypothesis, we find statistically significant evidence which supports the denoising hypothesis for improving the accuracy of NNAR forecasts. Thus, it is noise and not seasonality which hinders NNAR forecasting capabilities.     

双水相萃取技术在生物、医药方面的应用

讨论了双水相萃取技术的作用原理,分析了影响双水相萃取的因素,介绍了双水相萃取技术的特点及这一技术在生物和药物提取领域的应用,针对双水相萃取技术的特点及局限性对其应用前景进行了展望。     

基于改进型BP神经网络的字符识别算法研究

神经网络被广泛地应用于字符识别,通过对其难点问题的分析,为了提高字符识别率,本文应用改进型BP神经网络进行字符识别,该算法识别率高,速度快,可适用于多种高噪声环境中,实用性很强。     

高分辨率铁尾矿遥感光谱特征分析与信息提取

遥感监测尾矿是矿山调查和监管的科学方法,也是地理国情监测的基础内容。研究了铁尾矿遥感影像解译标志和光谱特征,建立铁尾矿遥感信息的提取技术流程。利用尾矿光谱特征与纹理结构的特点,构建了铁尾矿遥感增强处理的RTI数学模型。并以唐山地区的铁尾矿及固体废弃物作为研究区,分析了模型的影响因子和有效性。为尾矿资源的自动监测和目标提取提供了新的处理手段。