Catalytic decomposition of hydrogen peroxide in the presence of alkylpyridines: Runaway scenarios studies

A number of runaway scenarios of the excess of hydrogen peroxide used during the N-oxidation of alkylpyridines, under closed and open conditions, were examined. It was found that, in most cases, if the volume of the liquid hydrogen peroxide solution occupies more than 10% of the total volume of a closed system (e.g. reactor and vent line between reactor and blockage), the production of gases raises the pressure so quickly that evaporation is completely suppressed. Higher than 70% filling levels result in complete expansion of the liquid. The MTSR(t) of the system falls rapidly if the normal process temperature is high, but if a runaway occurs exactly at the end of dosing, MTST will be very high and secondary decompositions will rapidly develop. The results of this study are currently being used to critically assess the current approaches and further the study of inherently safer designs.     

双丙胶乳生产工艺及其产物的热危险性试验研究

为探究双丙胶乳生产工艺热危险性及其产物的热分解特性,开展双丙胶乳合成工艺试验,采用全自动反应量热仪(RC1e),测定反应过程中的放热特性;采用同步热重(TG)分析仪,测试反应产物在空气和氮气气氛中的热解性能;评估反应过程的热危险性,分析反应生成的双丙胶乳的热分解过程,并运用等转化率动力学方法(Starink法和Friedman法)计算产物热分解过程中的表观活化能(E_a)。结果表明:双丙胶乳生产工艺的反应热危险性等级为1级,相对安全;在空气气氛下,双丙胶乳的热分解过程包括4个阶段,且几乎无残余,而在氮气气氛下,双丙胶乳的热分解过程分为3个阶段,残炭率约为9.22%;通过Starink法和Friedman法计算得到的E_a范围分别为32.65～113.45 kJ/mol和29.70～175.90 kJ/mol。     

Source apportionment and specific-source-site risk of quinolone antibiotics for effluent-receiving urban rivers and groundwater in a city,China

There is a large surface-groundwater exchange downstream of wastewater treatment plants(WWTPs),and antibiotics upstream may influence sites downstream of rivers.Thus,sam-ples from 9 effluent-receiving urban rivers(ERURs)and 12 groundwater sites were collected in Shijiazhuang City in December 2020 and April 2021.For ERURs,8 out of 13 target quinolone antibiotics(QNs)were detected,and the total concentration of QNs in December and April were 100.6-4,398 ng/L and 8.02-2,476 ng/L,respectively.For groundwater,all target QNs were detected,and the total QNs concentration was 1.09-23.03 ng/L for December and 4.54-170.3 ng/L for April.The distribution of QNs was dissimilar between ERURs and ground-water.Most QN concentrations were weakly correlated with land use types in the system.The results of a positive matrix factorization model(PMF)indicated four potential sources of QNs in both ERURs and groundwater,and WWTP effluents were the main source of QNs.From December to April,the contribution of WWTP effluents and agricultural emissions increased,while livestock activities decreased.Singular value decomposition(SVD)results showed that the spatial variation of most QNs was mainly contributed by sites downstream(7.09％ -88.86％ )of ERURs.Then,a new method that combined the results of SVD and PMF was developed for a specific-source-site risk quotient(SRQ),and the SRQ for QNs was at high level,especially for the sites downstream of WWTPs.Regarding temporal variation,the SRQ for WWTP effluents,aquaculture,and agricultural emissions increased.Therefore,in order to control the antibiotic pollution,more attention should be paid to WWTP efflu-ents,aquaculture,and agricultural emission sources for the benefit of sites downstream of WWTPs.     

Functional decomposition—A contribution to overcome the parameter space explosion during validation of highly automated driving

Abstract

Objective: Particular testing by functional decomposition of the automated driving function can potentially contribute to reducing the effort of validating highly automated driving functions. In this study, the required size of test suites for scenario-based testing and the potential to reduce it by functional decomposition are quantified for the first time.

Methods: The required size of test suites for scenario-based approval of a so-called Autobahn-Chauffeur (SAE Level 3) is analyzed for an exemplary set of scenarios. Based on studies of data from failure analyses in other domains, the possible range for the required test coverage is narrowed down and suitable discretization steps, as well as ranges for the influence parameters, are assumed. Based on those assumptions, the size of the test suites for testing the complete system is quantified. The effects that lead to a reduction in the parameter space for particular testing of the decomposed driving function are analyzed and the potential to reduce the validation effort is estimated by comparing the resulting test suite sizes for both methods.

Results: The combination of all effects leads to a reduction in the test suites’ size by a factor between 20 and 130, depending on the required test coverage. This means that the size of the required test suite can be reduced by 95–99% by particular testing compared to scenario-based testing of the complete system.

Conclusions: The reduction potential is a valuable contribution to overcome the parameter space explosion during the validation of highly automated driving. However, this study is based on assumptions and only a small set of exemplary scenarios. Thus, the findings have to be validated in further studies.