Misbehaviour Prediction for Autonomous Driving Systems

Deep Neural Networks (DNNs) are the core component of modern autonomous driving systems. To date, it is still unrealistic that a DNN will generalize correctly in all driving conditions. Current testing techniques consist of offline solutions that identify adversarial or corner cases for improving the training phase, and little has been done for enabling online healing of DNN-based vehicles. In this paper, we address the problem of estimating the confidence of DNNs in response to unexpected execution contexts with the purpose of predicting potential safety-critical misbehaviours such as out of bound episodes or collisions. Our approach SelfOracle is based on a novel concept of self-assessment oracle, which monitors the DNN confidence at runtime, to predict unsupported driving scenarios in advance. SelfOracle uses autoencoder and time-series-based anomaly detection to reconstruct the driving scenarios seen by the car, and determine the confidence boundary of normal/unsupported conditions. In our empirical assessment, we evaluated the effectiveness of different variants of SelfOracle at predicting injected anomalous driving contexts, using DNN models and simulation environment from Udacity. Results show that, overall, SelfOracle can predict 77% misbehaviours, up to 6 seconds in advance, outperforming the online input validation approach of DeepRoad by a factor almost equal to 3.Comment: 11 page

Generative Design in Minecraft (GDMC), Settlement Generation Competition

This paper introduces the settlement generation competition for Minecraft, the first part of the Generative Design in Minecraft challenge. The settlement generation competition is about creating Artificial Intelligence (AI) agents that can produce functional, aesthetically appealing and believable settlements adapted to a given Minecraft map - ideally at a level that can compete with human created designs. The aim of the competition is to advance procedural content generation for games, especially in overcoming the challenges of adaptive and holistic PCG. The paper introduces the technical details of the challenge, but mostly focuses on what challenges this competition provides and why they are scientifically relevant.Comment: 10 pages, 5 figures, Part of the Foundations of Digital Games 2018 proceedings, as part of the workshop on Procedural Content Generatio

The 30/20 GHz flight experiment system, phase 2. Volume 2: Experiment system description

A detailed technical description of the 30/20 GHz flight experiment system is presented. The overall communication system is described with performance analyses, communication operations, and experiment plans. Hardware descriptions of the payload are given with the tradeoff studies that led to the final design. The spacecraft bus which carries the payload is discussed and its interface with the launch vehicle system is described. Finally, the hardwares and the operations of the terrestrial segment are presented

Degradation in PEM Fuel Cells and Mitigation Strategies Using System Design and Control

The rapid miniaturization of electronics, sensors, and actuators has reduced the cost of field sensor networks and enabled more functionality in ever smaller packages. Networks of field sensors have emerging applications in environmental monitoring, in disaster monitoring, security, and agriculture. Batteries limit potential applications due to their low specific energy. A promising alternative is photovoltaics. Photovoltaics require large, bulky panels and are impacted by daily and seasonal variation in solar insolation that requires coupling to a backup power source. Polymer electrolyte membrane (PEM) fuel cells are a promising alternative, because they are clean, quiet, and operate at high efficiencies. However, challenges remain in achieving long lives due to catalyst degradation and hydrogen storage. In this chapter, we present a design framework for high-energy fuel cell power supplies applied to field sensor networks. The aim is to achieve long operational lives by controlling degradation and utilizing high-energy density fuels such as lithium hydride to produce hydrogen. Lithium hydride in combination with fuel-cell wastewater or ambient humidity can achieve fuel specific energy of 5000 Wh/kg. The results of the study show that the PEM hybrid system fueled using lithium hydride offers a three- to fivefold reduction in mass compared to state-of-the-art batteries

초임계수 내 헥실 설파이드와 헥산사이올의 탈황 반응 메커니즘

학위논문(박사)--서울대학교 대학원 :공과대학 화학생물공학부,2020. 2. 이윤우.오늘날 전세계적으로 에너지에 대한 수요가 지속적으로 증가하면서 석유 자원에 대한 수요 역시 증가하고 있으나 고갈되어가는 기존의 경질 원유만으로는 이러한 수요를 따라가기 어렵다. 이에 따라 매장량이 많을 뿐만 아니라 기술 개발로 인해 생산 비용이 크게 감소하여 가격 경쟁력을 가진 중질 원유가 대안으로 각광받고 있다. 하지만 중질 원유를 활용하는 것은 쉽지 않다. 중질 원유는 점도가 높고 밀도가 높으며 많은 양의 황(2~5 wt%)과 V, Ni, Fe, Na, Ca 등의 중금속이 함유되어 있다. 기존의 정유 공정에서 중질 원유를 전처리 없이 사용할 경우 관이나 파이프가 막히거나 부식될 뿐만 아니라 촉매 비활성화를 일으키고, 디솔터에서 물-오일의 유화액이 형성되는 등의 여러가지 심각한 문제를 야기할 수 있다. 또한 높은 황 함량으로 인해 연소 과정에서 다량의 이산화황을 생성할 수 있어서 산성비를 일으키고 토양 및 담수 체의 pH를 낮추는 등의 심각한 환경 영향을 줄 수 있다. 중질 원유를 활용하기 위해서는 황 및 중금속과 같은 불순물을 제거하는 중질 원유 개질 공정이 필수적이다. 초임계수(SCW, Tc = 647.5 k, Pc = 22.05 MPa)는 중질 원유를 개질하는 유망한 기술이다. 초임계수는 뛰어난 열 및 물질전달 특성을 가지고 있을 뿐만 아니라 높은 해리 상수(Kw)을 가지고 있어 H+를 고농도로 생성하고, 유전 상수가 낮아서 극성이 낮아 유기 화합물을 용해시킬 수 있다. 초임계수는 중질 원유 내의 탄화수소의 분해, 코크스 형성의 억제 및 황의 제거에 매우 효과적인 것으로 알려져 있다. 그러나 아직까지 초임계수에서의 탈황 메커니즘은 불분명하다. 이 연구에서는 열분해 및 초임계수 분해에서 헥실 설파이드와 헥산사이올의 탈황 메커니즘을 알아보았다. 헥실 설파이드와 헥산사이올을 400℃에서 0-30 분 동안 열분해와 초임계수 분해(24.7-25.6MPa)로 탈황 반응을 진행하고 가스 크로마토그래피를 이용하여 분석하였다. 또한 화학반응 데이터베이스를 기반으로 반응 경로를 예측하는 Automatic Reaction Mechanism Generator(RMG) 프로그램 및 밀도 함수 이론을 기반으로 하는 양자 화학 계산 프로그램인 Gaussian 09 프로그램을 이용하여 탈황 반응의 메커니즘을 연구하였다. 실험 결과, 열분해와 초임계수 분해는 생성물의 조성에서 상당한 차이가 있었다. 헥실 설파이드와 헥산사이올의 열분해에서 최종 생성물로 C6 탄화수소(헥산, 헥센)이 주로 검출되었으나, 초임계수 분해에서는 C6-탄화수소뿐만 아니라 C5-탄화수소인 펜탄이 최대 21.4wt%를 차지하는 주요 생성물로 검출되었다. 또한 헥실 설파이드와 헥산사이올의 열분해를 거쳐 사이오펜, 알킬 시아사이클로알칸을 비롯한 방향족 황 화합물 형태의 생성물이 5wt% 이상 검출된 반면에, 초임계수 분해 생성물에서는 1wt% 미만의 소량만이 검출되었다. 열분해에서의 반응 경로는 먼저 RMG를 통해 반응 모델을 세우고 다양한 문헌 및 실험 결과를 통해 보정하였다. 헥실 설파이드 및 헥산사이올의 열분해는 수소 결핍 공정(hydrogen deficient process)으로, 사이오펜이 형성될 뿐만 아니라 헥산 대 헥센의 낮은 비를 가지는 것을 알 수 있었다. 초임계수 분해에서 반응 경로는 Gaussian 09를 사용하여 밀도 함수 이론을 통해 알아보았다. 초임계수 분해에서 물은 수소 전달 촉매, 반응물, 및 촉매로 작용했다. 이는 초임계수 분해는 헥실 설파이드 및 헥산 티올의 황을 저분자의 형태로 효과적으로 제거하였으나 열 분해는 수소 결핍 공정으로 인해 사이오펜 및 고리형 황 화합물 등을 생성하였던 실험 결과를 잘 설명해줄 수 있었다. 이러한 결과는 일반적인 알킬 설파이드 및 알킬 사이올의 분해에서 초임계수 분해를 통한 황의 제거가 열분해보다 더 효율적임을 시사한다. 초임계수에서 물은 알킬 사이올의 수소 전달 촉매로서 작용하여 황을 황화수소 가스 형태로 제거할 뿐만 아니라 알킬 설파이드 및 알킬 티올의 주요 중간 화합물들을 분해하는 반응에서 반응물이자 촉매로 참여하여 수소 및 산소를 공급하여 황화수소, 일산화탄소 및 이산화탄소 등으로 황을 제거한다. 대조적으로, 열분해에서는 수소 결핍으로 인해 사이오펜과 같은 방향족 황 화합물은 생성된다. 이 연구는 황 화합물의 초임계수 분해 메커니즘 및 초임계수 분해에서물의 역할에 대해서 알아보았으며, 앞으로 초임계수에서 다양한 탈황 반응 연구에 도움이 될 것을 기대한다. 또한 차후 다량의 황을 포함하는 중질유의 업그레이딩에 공정 개발에 큰 도움을 줄 수 있을 것이라 기대한다.Nowadays, the production of heavy crude oil has increased significantly as the cost for production are decreasing with technology developments and the conventional light crude oil are being depleted. Despite these increases in the production of heavy crude oil, it is very challenging to utilize. Heavy crude oil has heavy molecular compositions such as asphaltenes and high sulfur contents ranging from 2 to 5 wt%. Not only can heavy crude oil cause severe problems in the existing refinery process such as fouling, corrosion of pipe, catalyst deactivation, and water-oil emulsion in desalter, but also it can produce a large amount of sulfur dioxide in the combustion process due to its high sulfur content, which can have serious environmental impacts such as acid rain and lowering the pH of soil and freshwater bodies. Heavy oil needs upgrading process with removing impurities such as sulfur and heavy metals. Supercritical water (SCW, Tc= 647.5 k, Pc=22.05 MPa) is regarded as a promising technology to upgrade the heavy oil. SCW has a high diffusivity with favorable transport properties, a high dissociation constant (Kw) generating high H+ concentration, and a low relative dielectric constant dissolving the organic compounds with low polarity. SCW has been very effective in the decomposition of hydrocarbons, the inhibition of coke formation and even the desulfurization in the upgrading of heavy oil. Despite the high sulfur content in heavy oil, however, the mechanisms of desulfurization in SCW still remain unclear. In this study, desulfurization of hexyl sulfide and hexanethiol using supercritical water (SCW) was investigated by combining experimental and computational methods to study the desulfurization of alkyl sulfides and thiols in SCW. Desulfurization was conducted for 0 ~ 30 min at 400 °C using thermal decomposition and SCW decomposition (24.7 ~ 25.6 MPa), and the reaction pathways were built using the automated Reaction Mechanism Generator (RMG) and Gaussian 09. In the experimental results, thermal decomposition and SCW decomposition showed considerable differences in the products composition. C6-hydrocarbons (hexane, hexene) were main products in the thermal decomposition, whereas C5-hydrocarbon (pentane) in addition to C6-hydrocarbons were main products with higher alkane to alkene ratio. Also, in thermal decomposition, aromatic sulfur compounds including thiophenes and alkyl-thiacycloalkanes were found, but in SCW decomposition, thiophenes were not detected and alkyl-thiacycloalkanes were detected in a relatively small amount. To investigate the reactions pathways in the thermal decomposition of hexyl sulfide and hexanethiol, detailed kinetic models were set using automated reaction mechanism generation software (RMG) and corrected through various works of literature and experimental results. The thermal decomposition of hexyl sulfide and hexanethiol is a hydrogen-deficient process with the formation of thiophene formation and the low ratio of hexane to hexene. The reactions pathways in SCW decomposition were investigated by the quantum chemistry calculations with density functional theory using Gaussian 09 to study the role of water in SCW decomposition. In SCW decomposition, water played the major roles: H-transfer catalyst in the unimolecular decomposition of hexanethiol, reactants in the decomposition of hexylthioaldehyde, and even catalyst in the decomposition of hexylthioaldehyde. These computational results support the experimental results that SCW decomposition effectively removes sulfur in hexyl sulfide and hexanethiol as low molecular sulfur compounds while thermal decomposition produces high molecular sulfur compounds such as thiophenes and alkyl-thiacycloalkanes with hydrogen deficient process. These results suggest that the removal of sulfur in SCW decomposition is more efficient than thermal decomposition in the decomposition of alkyl sulfides and alkyl thiol. In SCW, water can act as a H-transfer catalyst in the unimolecular decomposition of alkyl thiol to eliminate sulfur as a H2S gas, and it also acts as reactants in the decomposition of alkyl thioaldehyde, the major intermediate compound of alkyl sulfide and alkyl thiol, to eliminate sulfur as a H2S, CO, and CO2 gas by providing H source and O source as well as acts as catalyst. In contrast, aromatic sulfur compounds such as thiophenes are produced due to the hydrogen deficiency in thermal decomposition. These experimental and computational studies would present a reliable guide to the various mechanisms of organosulfur compounds in thermal decomposition and SCW decomposition with a deeper understanding of the role of water. It can give great help in the upgrading of heavy oil which contains a large amount of sulfur with the optimization of process design for the SCW upgrading.1. Introduction 1 2. Background 7 2.1. Heavy crude oil 7 2.1.1. The needs for utilizing heavy crude oil 7 2.1.2. Challenges for utilizing heavy crude oil 9 2.2. Supercritical water 13 2.2.1. Supercritical fluids 13 2.2.2. The characteristics of supercritical water 16 2.3. Upgrading of heavy oil in supercritical water 19 2.4. Desulfurization in supercritical water 24 2.4.1. The desulfurization in supercritical water 24 2.4.2. Desulfurization mechanism in supercritical water 27 3. Experimental and computational methods 30 3.1. Raw materials 30 3.2. Experimental apparatus 31 3.3. Experimental procedure 34 3.4. Analytical methods 36 3.5. Computational methods 38 4. Results and discussion 43 4.1. Hexyl sulfide decomposition 43 4.1.1. Characterization of the products 43 4.1.2. Quantification of the products 46 4.2. Hexanethiol decomposition 53 4.3. The change of sulfur balances 59 4.4. The mechanism construction in thermal decomposition 62 4.4.1. The thermal decomposition mechanism of hexnaethiol 63 4.4.2. The thermal decomposition mechanism of hexyl sulfide 72 4.5. The mechanism construction in SCW decomposition 78 4.4.1. The SCW decomposition mechanism of hexanethiol 79 4.4.2. The SCW decomposition mechanism of hexyl sulfide 85 5. Conclusions 87 Appendix. Input for reaction mechanism generator 90 Reference 96 Abstract in korean 103Docto

Preparation and characterization of dual-curable off-stoichiometric amine-epoxy thermosets with latent reactivity

A new family of dual-curable poly(hydroxyamine)-poly(ether) thermosets based on off-stoichiometric amine-epoxy formulations has been prepared and characterized. The first curing stage was a selflimiting click epoxy-amine polycondensation with an excess of epoxides and the second stage was an anionic homopolymerization of the unreacted epoxy groups, initiated by a latent base. The curing process was sequential with storage stable intermediate materials. The latency of these partially-cured intermediate materials was established not only by a thermally activated base generator, but also by the vitrification of the formulations. The intermediate and final materials exhibit a wide range of properties depending on the relative contribution of both curing stages. Intermediate materials can either be shape conformable solids, or liquids that are applicable as adhesives. Fully cured materials exhibit shapememory effect.Postprint (author's final draft

Advanced Materials and Technologies in Nanogenerators

This reprint discusses the various applications, new materials, and evolution in the field of nanogenerators. This lays the foundation for the popularization of their broad applications in energy science, environmental protection, wearable electronics, self-powered sensors, medical science, robotics, and artificial intelligence