A Temporal-Pattern Backdoor Attack to Deep Reinforcement Learning

Deep reinforcement learning (DRL) has made significant achievements in many real-world applications. But these real-world applications typically can only provide partial observations for making decisions due to occlusions and noisy sensors. However, partial state observability can be used to hide malicious behaviors for backdoors. In this paper, we explore the sequential nature of DRL and propose a novel temporal-pattern backdoor attack to DRL, whose trigger is a set of temporal constraints on a sequence of observations rather than a single observation, and effect can be kept in a controllable duration rather than in the instant. We validate our proposed backdoor attack to a typical job scheduling task in cloud computing. Numerous experimental results show that our backdoor can achieve excellent effectiveness, stealthiness, and sustainability. Our backdoor's average clean data accuracy and attack success rate can reach 97.8% and 97.5%, respectively

Development of an incoherent broad-band cavity-enhanced aerosol extinction spectrometer and its application to measurement of aerosol optical hygroscopicity

We report on the development of a blue light-emitting-diode-based incoherent broad-band cavity-enhanced absorption spectroscopy (IBBCEAS) instrument for the measurement of the aerosol extinction coefficient at \u1d706=461  nm. With an effective absorption path length of 2.8 km, an optimum detection limit of 0.05  Mm−1 (5×10−10  cm−1) was achieved with an averaging time of 84 s. The baseline drift of the developed spectrometer was about ±0.3  Mm−1 over 2.5 h (1\u1d70e standard deviation). The performance of the system was evaluated with laboratory-generated monodispersed polystyrene latex (PSL) spheres. The retrieved complex refractive index of PSL agreed well with previously reported values. The relative humidity (RH) dependence of the aerosol extinction coefficient was measured using IBBCEAS. The measured extinction enhancement factor values for 200 nm dry ammonium sulphate particles at different RH were in good agreement with the modeled values. Field performance of the aerosol extinction spectrometer was demonstrated at the Hefei Radiation Observatory site

Linkage Mapping of Stem Saccharification Digestibility in Rice

Rice is the staple food of almost half of the world population, and in excess 90% of it is grown and consumed in Asia, but the disposal of rice straw poses a problem for farmers, who often burn it in the fields, causing health and environmental problems. However, with increased focus on the development of sustainable biofuel production, rice straw has been recognized as a potential feedstock for non-food derived biofuel production. Currently, the commercial realization of rice as a biofuel feedstock is constrained by the high cost of industrial saccharification processes needed to release sugar for fermentation. This study is focused on the alteration of lignin content, and cell wall chemotypes and structures, and their effects on the saccharification potential of rice lignocellulosic biomass. A recombinant inbred lines (RILs) population derived from a cross between the lowland rice variety IR1552 and the upland rice variety Azucena with 271 molecular markers for quantitative trait SNP (QTS) analyses was used. After association analysis of 271 markers for saccharification potential, 1 locus and 4 pairs of epistatic loci were found to contribute to the enzymatic digestibility phenotype, and an inverse relationship between reducing sugar and lignin content in these recombinant inbred lines was identified. As a result of QTS analyses, several cell-wall associated candidate genes are proposed that may be useful for marker-assisted breeding and may aid breeders to produce potential high saccharification rice varieties

A high-density organoclay-free oil base drilling fluid based on supramolecular chemistry

Abstract: Based on supramolecular chemistry, a rheology modifier CFZTQ-1 for oil base drilling fluids was developed, and an innovative high-density organoclay-free oil base drilling fluid system centering on CFZTQ-1 was designed, evaluated and applied in the field. CFZTQ-1 can strongly increase the elasticity of invert emulsion due to the supramolecular structure assembled in water phase; CFZTQ-1 has stronger effect in elevating the yield point and suspension ability than several foreign rheology modifiers; the synergistic effect with organoclay also makes CFZTQ-1 available in traditional clay-contained invert emulsion drilling fluids. Through the category and dosage optimization of related additives, the formula of the high-density organoclay-free oil base drilling fluid was established and its performance was evaluated. The organoclay-free drilling fluid owns favorable rheology with density of 2.40−2.60 g/cm3, yield point of 13−17 Pa, moderate apparent viscosity and relative low plastic viscosity; after hot rolling at 240 °C, the drilling fluid still keeps a stable performance as its viscosity only increases slightly, its high temperature and high pressure (HTHP) filtration loss is about 10 mL and its electrical stability is greater than 400 V. This innovative drilling fluid system achieves excellent field application as well. Key words: oil base drilling fluid, supramolecular chemistry, rheology modifier, viscoelasticity, drilling fluid performanc

The Influence of Instrumental Line Shape Degradation on Gas Retrievals and Observation of Greenhouse Gases in Maoming, China

The instrument line shape (ILS), as a very important parameter, has a significant influence on the inversion of trace gas concentration. Different levels of ILS degradation for H2O, CO2, CH4, and CO gases were investigated, and the influence of ILS on the inversion of column-averaged dry air mole fractions (DMFs) was assessed. Our results indicate that the averages of XH2O, XCH4, and XCO with modulation efficiency (ME) amplitude values have a positive correlation, the correlation coefficients are 0.9925, 0.9968, and 0.9981 respectively, whereas the relationship between the average of XCO2 and ME is a negative correlation with 0.986 correlation coefficient. For a typical ILS degradation, a decrease of 5% in the modulation efficiency amplitude value results in the average of XCO2 changing by 0.744%, XCH4 and XH2O are less sensitive species, with average values of −0.206% and −0.464%, whereas XCO shows the strongest intraday variability with an average value of −0.238%. However, with a decrease of 2‰ in the phase error (PE) value, the average of XCO changed by −0.150%, XCO2 and XH2O almost coincided with the same average value of −0.141%, whereas XCH4 was the least sensitive species with an average value of −0.133%. At the same time, we measured the ILS for EM27/SUN spectrometers—the mean values of modulation efficiency amplitudes and phase errors were 0.9611 and 0.00593. Compared with standard values, the modulation efficiency amplitudes and the phase error deviations were 2.450% and 0.433%. During the observation period, the daily average of XCO2 ranged from 415.09 to 421.78 ppm. XCH4 ranged from 1.96 to 2.02 ppm with a mean of 1.982 ppm, and the daily average of XCO ranged from 0.118 to 0.157 ppm with a mean of 0.137 ppm. For the relationship between XCO2 and XCH4, the linear regression line shows a good correlation with the correlation coefficient R2 ≥ 0.5. Especially, for the correlation coefficient R2 = 0.82 on 8 October, our studies found a weak correlation in the variation of CO2 and CO during the observations. The correlation coefficient R2 ≥ 0.5 was only found on 30 September and 3 October. The trajectories dram at a height of 10 km give a hint of trace gas transport from the bay of western India, Bengal, and the Arabian Sea, whereas for the trajectories dram boundary layer height, trace gases were transported from southwest and east of China. These results provide a theoretical basis to understand the time and space distribution and the changes of greenhouse gas in the atmosphere as well as providing a theoretical basis for calculations of atmospheric radiation transmission

Concordance of tomographic ultrasound and multiplanar ultrasound in detecting levator ani muscle injury in patients with pelvic organ prolapse.

AIM:To compare the evaluations of evaluate levator ani muscle injury (LAMI) by tomographic ultrasound imaging (TUI) and multiplanar (MP) ultrasound in patients with pelvic organ prolapse (POP). METHOD:This retrospective analysis studied women who underwent International Continence Society POP quantification examination between October 2015 and June 2016. LAMI was assessed by both TUI and MP ultrasounds. Concordance of these two testing results was analyzed. Their correlations with clinical symptoms were also studied. RESULTS:A total of 135 women were included. All the patients with POP had a minimal LAMI depth ≥ 7 mm. Two examinations, TUI and MP, had satisfactory concordance (k = 0.71, P < 0.01). Depth of LAMI in the coronal plane demonstrated good agreement with TUI scores (r = 0.84; P < 0.01). After controlling for age, BMI, and parity, to have clinically significant POP and POP symptoms, the odds ratios (ORs) for the depth of LAMI in the coronal plane were 1.31 (95% CI 1.19-1.44) and 1.25 (95% CI 1.14-1.36), and for TUI scores were 1.72 (95% CI 1.37-2.17) and 1.63 (95% CI 1.31-2.03). Receiver operating characteristic curve analyses showed a cutoff depth of 7 mm of LAMI yielded a sensitivity of 62% and specificity of 80% for POP symptoms. CONCLUSIONS:TUI and MP had satisfactory concordance in detecting LAMI and correlated with clinical symptoms of POP

Dual phase nano-particulate AlN composite - A kind of ceramics with high strength and ductility

Ceramics are widely used in many fields due to their excellent properties. However, the brittle fracture is a short board restricting their applications. To understand their deformation mechanism and explore a way to enhance both the strength and ductility, we investigated the mechanical behaviour of dual-phase AlNs composed of amorphous AlN matrix and crystalline nanoparticles under compression via molecular dynamics simulations. The stress concentration exists at the interface of nanocomposite AlN, where the particles and matrix are in the tensile and compressive states of stress, respectively. Strain hardening occurs when crystalline nanoparticle fraction fv ≥ 40.9%, attributed to the intersection between shear bands. The phase transformation from wurtzite structure (B4) to graphene-like structure (GL) is observed in the crystalline phase, as a result of high hydrostatic stress. After phase transformation, the particle might be cut into half during further compression along with the recovery of the GL structure to the wurtzite structure that could still bear load. The investigation of the effects of the volume fraction, surface-to-volume ratio, distribution pattern of the crystalline nanoparticles indicates that the dual-phase AlN nanocomposite with fv ≥ 40.9% and triangle distribution of particles would possess both higher strength and ductility.</p

Investigation of Interaction between Dislocation Loop and Coherent Twin Boundary in BCC Ta Film during Nanoindentation

In this work, the interaction between dislocation loop (DL) and coherent twin boundary (CTB) in a body-centered cubic (BCC) tantalum (Ta) film during nanoindentation was investigated with molecular dynamics (MD) simulation. The formation and propagation of &lt;111&gt; full DLs in the nanotwinned (nt) Ta film during the indentation was observed, and it was found that CTB can strongly affect the stress distribution in the Ta film, and thus change the motion and type of dislocations. There are three kinds of mechanisms for the interaction between DL and CTB in a twinned BCC Ta film: (i) dislocation absorption, (ii) dislocation desorption, and (iii) direct slip transmission. The nucleation of twin boundary dislocations and the formation of the steps in CTB were also observed during the indentation. The mechanisms presented in this work can provide atomic images for understanding the plastic deformation of BCC metals with mirror-symmetry grain boundary structures, and provide available information for the evaluation and design of high-performance nt BCC metallic thin film coatings