Electromagnetic Sensor and Actuator Attacks on Power Converters for Electric Vehicles

Alleviating range anxiety for electric vehicles (i.e., whether such vehicles can be relied upon to travel long distances in a timely manner) is critical for sustainable transportation. Extremely fast charging (XFC), whereby electric vehicles (EV) can be quickly recharged in the time frame it takes to refuel an internal combustion engine, has been proposed to alleviate this concern. A critical component of these chargers is the efficient and proper operation of power converters that convert AC to DC power and otherwise regulate power delivery to vehicles. These converters rely on the integrity of sensor and actuation signals. In this work the operation of state-of-the art XFC converters is assessed in adversarial conditions, specifically against Intentional Electromagnetic Interference Attacks (IEMI). The targeted system is analyzed with the goal of determining possible weak points for IEMI, viz. voltage and current sensor outputs and gate control signals. This work demonstrates that, with relatively low power levels, an adversary is able to manipulate the voltage and current sensor outputs necessary to ensure the proper operation of the converters. Furthermore, in the first attack of its kind, it is shown that the gate signal that controls the converter switches can be manipulated, to catastrophic effect; i.e., it is possible for an attacker to control the switching state of individual transistors to cause irreparable damage to the converter and associated systems. Finally, a discussion of countermeasures for hardware designers to mitigate IEMI-based attacks is provided.Comment: Accepted by IEEE S&P Workshop on the Internet of Safe Things 202

Age-specific seriousness of avian influenza A(H7N9) in the second-wave epidemic in China

Poster Presentations 2 - Diseases at the Interface of Humans, Wildlife and Other Animals: no. 23.049PURPOSE: In spring 2013, a novel avian influenza A(H7N9) emerged in China causing more than 130 human infections mostly in the eastern provinces. The hospital fatality risk of A(H7N9) were about 35% and caused severe illness especially in older patients. In winter 2013-14, a second wave of A(H7N9) began with higher burden in the southern provinces in China. We estimated the relative risk of serious illness of patients aged 65 or above in the second wave of A(H7N9) epidemic, accounting for potential age-specific differences in poultry exposure …published_or_final_versio

Age-specific seriousness of avian influenza A(H7N9) in the second-wave epidemic in China

Poster Presentations 2 - Diseases at the Interface of Humans, Wildlife and Other Animals: no. 23.049PURPOSE: In spring 2013, a novel avian influenza A(H7N9) emerged in China causing more than 130 human infections mostly in the eastern provinces. The hospital fatality risk of A(H7N9) were about 35% and caused severe illness especially in older patients. In winter 2013-14, a second wave of A(H7N9) began with higher burden in the southern provinces in China. We estimated the relative risk of serious illness of patients aged 65 or above in the second wave of A(H7N9) epidemic, accounting for potential age-specific differences in poultry exposure …published_or_final_versio

Partial Regularity of solutions to the Four-dimensional Navier-Stokes equations at the first blow-up time

The solutions of incompressible Navier-Stokes equations in four spatial dimensions are considered. We prove that the two-dimensional Hausdorff measure of the set of singular points at the first blow-up time is equal to zero.Comment: 19 pages, a comment regarding five or higher dimensional case is added in Remark 1.3. accepted by Comm. Math. Phy

Experimentally Engineering the Edge Termination of Graphene Nanoribbons

The edges of graphene nanoribbons (GNRs) have attracted much interest due to their potentially strong influence on GNR electronic and magnetic properties. Here we report the ability to engineer the microscopic edge termination of high quality GNRs via hydrogen plasma etching. Using a combination of high-resolution scanning tunneling microscopy and first-principles calculations, we have determined the exact atomic structure of plasma-etched GNR edges and established the chemical nature of terminating functional groups for zigzag, armchair and chiral edge orientations. We find that the edges of hydrogen-plasma-etched GNRs are generally flat, free of structural reconstructions and are terminated by hydrogen atoms with no rehybridization of the outermost carbon edge atoms. Both zigzag and chiral edges show the presence of edge states.Comment: 16+9 pages, 3+4 figure

Electrically driven light emission from hot single-walled carbon nanotubes at various temperatures and ambient pressures

Electroluminescence of individual single-walled carbon nanotubes down to ∼15K is measured. We observe electrically driven light emission from suspended quasimetallic nanotubes in vacuum down to ∼15K and under different gas pressures at room temperature. Light emission is found to originate from hot electrons in the presence of electrically driven nonequilibrium optical phonons. Reduced light emission is observed in exponential manner as electron and optical phonon temperatures in the nanotube are lowered by lower ambient temperature or higher gas pressure. The results reveal over wide ambient conditions, light emission in a suspended tube is from thermally excited electron-hole recombination

On the L_p-solvability of higher order parabolic and elliptic systems with BMO coefficients

We prove the solvability in Sobolev spaces for both divergence and non-divergence form higher order parabolic and elliptic systems in the whole space, on a half space, and on a bounded domain. The leading coefficients are assumed to be merely measurable in the time variable and have small mean oscillations with respect to the spatial variables in small balls or cylinders. For the proof, we develop a set of new techniques to produce mean oscillation estimates for systems on a half space.Comment: 44 pages, introduction revised, references expanded. To appear in Arch. Rational Mech. Ana

Co3O4 Nanocrystals on Graphene as a Synergistic Catalyst for Oxygen Reduction Reaction

Catalysts for oxygen reduction and evolution reactions are at the heart of key renewable energy technologies including fuel cells and water splitting. Despite tremendous efforts, developing oxygen electrode catalysts with high activity at low costs remains a grand challenge. Here, we report a hybrid material of Co3O4 nanocrystals grown on reduced graphene oxide (GO) as a high-performance bi-functional catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). While Co3O4 or graphene oxide alone has little catalytic activity, their hybrid exhibits an unexpected, surprisingly high ORR activity that is further enhanced by nitrogen-doping of graphene. The Co3O4/N-doped graphene hybrid exhibits similar catalytic activity but superior stability to Pt in alkaline solutions. The same hybrid is also highly active for OER, making it a high performance non-precious metal based bi-catalyst for both ORR and OER. The unusual catalytic activity arises from synergetic chemical coupling effects between Co3O4 and graphene.Comment: published in Nature Material

Cost-effectiveness of introducing national seasonal influenza vaccination for adults aged 60 years and above in mainland China: a modelling analysis

BACKGROUND: China has an aging population with an increasing number of adults aged ≥ 60 years. Influenza causes a heavy disease burden in older adults, but can be alleviated by vaccination. We assessed the cost-effectiveness of a potential government-funded seasonal influenza vaccination program in older adults in China. METHODS: We characterized the health and economic impact of a fully funded influenza vaccination program for older adults using China-specific influenza disease burden, and related cost data, etc. Using a decision tree model, we calculated the incremental costs per quality-adjusted life year (QALY) gained of vaccination from the societal perspective, at a willingness-to-pay threshold equivalent to GDP per capita (US$8840). Moreover, we estimated the threshold vaccination costs, under which the fully funded vaccination program is cost-effective using GDP per capita as the willingness-to-pay threshold. RESULTS: Compared to current self-paid vaccination, a fully funded vaccination program is expected to prevent 19,812 (95$4832 (3460-8307), with a 98% probability of being cost-effective. The threshold vaccination cost is US$10.19 (6.08-13.65). However, variations exist between geographical regions, with Northeast and Central China having lower probabilities of cost-effectiveness. CONCLUSIONS: Our results support the implementation of a government fully funded older adult vaccination program in China. The regional analysis provides results across settings that may be relevant to other countries with similar disease burden and economic status, especially for low- and middle-income countries where such analysis is limited