Anomaly‐based intrusion detection of jamming attacks,local versus collaborative detection

We present intrusion detection algorithms to detect physical layer jamming attacks in wireless networks. We compare the performance of local algorithms on the basis of the signal‐to‐interference‐plus‐noise ratio (SINR) executing independently at several monitors, with a collaborative detection algorithm that fuses the outputs provided by these algorithms. The local algorithms fall into two categories: simple threshold that raise an alarm if the output of the SINR‐based metrics we consider deviates from a predefined detection threshold and cumulative sum (cusum) algorithms that raise an alarm if the aggregated output exceeds the predefined threshold. For collaborative detection, we use the Dempster–Shafer theory of evidence algorithm. We collect SINR traces from a real IEEE 802.11 network, and with the use of a new evaluation method, we evaluate both the local and the Dempster–Shafer algorithms in terms of the detection probability, false alarm rate, and their robustness to different detection threshold values, under different attack intensities. The evaluation shows that the cusums achieve higher performance than the simple threshold algorithms under all attack intensities. The Dempster–Shafer algorithm when combined with the simple algorithms, it can increase their performance by more than 80%, but for the cusum algorithms it does not substantially improve their already high performance.Copyright © 2013 John Wiley & Sons, Ltd.     

Overlay Design Mechanisms for Heterogeneous, Large-Scale, Dynamic P2P Systems

Large-scale, heterogeneous peer-to-peer (P2P) systems impose a set of diverse requirements. Current solutions do commonly only address a subset of these requirements since there are a number of trade-offs and constraints due to the different dimensions and aims they address. We present a novel approach for designing overlay networks for large-scale, highly dynamic, and heterogeneous P2P systems. A set of mechanisms is proposed to meet the complete set of requirements while keeping the trade-offs and constraints in balance. To handle effectively the large number of peers, they are clustered in manageable groups considering the requirements on their stability. The novelty in this approach is in the identification of the core services and operations of the aforementioned systems. On the basis of the requirements of those services and operations, peers are assigned the most suitable roles. Role relationships are further introduced to enable (and provide) incentives for the peers to adopt the most suitable roles while selecting an efficient overlay structure to preserve efficiency, robustness, and scalability. The proposed set of mechanisms is realized in Omicron, a novel hybrid P2P approach.     

Transport properties of silmethylene homo-polymers and random copolymers: experimental measurements and molecular simulation

A novel class of silicon-containing rubbers is proposed as membrane materials for separation of hydrocarbons of natural and associated petroleum gas. Homo-polymers of general formulas -Si(CH₃)₂CH₂- (PDMSM) and -Si(CH₃)₂CH₂CH₂CH₂- (PDMSTM) and the copolymers with the same randomly alternating repeat units were prepared by thermal initiated polymerization of strained silicon-containing four-member cycles. These polymers have low glass transition temperatures and reveal solubility controlled gas permeation properties. The highest permeability is characteristic for PDMSM, however, it has poor film forming properties. On the other hand, amorphous copolymers exhibit combination of good film forming properties and relatively high permeability. Transport properties of PDMSM were successfully simulated by molecular dynamics using a very efficient united-atom force field.     

Atorvastatin Decreases Triacylglycerol-Associated Risk of Vascular Events in Coronary Heart Disease Patients

High triacylglycerol (TAG) levels may predict vascular risk. The effect of a statin-induced reduction in TAG levels, irrespective of HDL-C increase, on clinical outcome has not yet been addressed by an endpoint study in patients with coronary heart disease (CHD). The GREACE study compared usual with structured care aimed at achieving LDL-C = 100 mg/dL (2.6 mmol/L) by dose titration with atorvastatin. All patients had CHD and were followed for 3 years. This post hoc analysis of GREACE examines the effect of statins on TAG levels and their relation with cardiovascular disease (CVD) events in all patients and in the subgroup of patients with metabolic syndrome (MetS). Baseline TAG levels >150 mg/dL (1.7 mmol/L) were predictive of subsequent CVD events [cardiac mortality, non-fatal myocardial infarction (MI), unstable angina (UA), revascularisation, congestive heart failure (CHF), and stroke] only in statin untreated patients. Stepwise regression analysis showed that with every 20% statin-related TAG reduction there was a decrease in CVD risk by 12% (HR 0.88, 95% CI 0.75–0.95, P = 0.007) in the structured care group vs. the usual care group, by 8% (HR 0.92, 95% CI 0.81–0.97, P = 0.02) in all statin treated patients vs. the untreated ones and by 15% (HR 0.85, 95% CI 0.65–0.94, P = 0.005) in those with MetS treated with a statin vs. those untreated. Using the same analysis but only taking into consideration vascular events (cardiac mortality, non-fatal MI, UA, revascularisation, and stroke) there was a 18% (HR = 0.82, 95% CI 0.57–0.96, P = 0.03) decrease in risk in the MetS (+) patients treated with a statin vs. those not on a statin, and a decrease in risk by 16% (HR = 0.84, 95% CI 0.53–1.07, P = 0.08), when only hard vascular endpoints (cardiac mortality, non-fatal MI, and stroke) were considered. TAG levels are predictive of subsequent CVD events in statin untreated CHD patients. Statin (mainly atorvastatin)-induced decrease in TAG levels was related to a significant reduction in subsequent CVD events. This benefit was more pronounced in CHD MetS (+) patients.     

Full Characterisation of Crambe abyssinica Hochst. Seed Oil

This work was dedicated to reporting the full chemical and physical characterisation of Crambe abyssinica Hochst. seed oil. The oil from the seeds was extracted using n-hexane. The seeds contain about 30?% oil. Density, refractive index, colour, smoke point, viscosity, acidity, saponification value, iodine value, fatty acid methyl esters, the relative position of fatty acids in C₁ and C₃ carbon glycerol, sterols, tocopherols, peroxide value, $ \mathop E\nolimits_{{1{\text{cm}}}}^{1\,\% } $ at 232?nm, and the susceptibility to oxidation measured by the Rancimat method were determined. The oil was found to contain high levels of unsaturated fatty acids, especially C22:1 (63.77?%). The dominant saturated acid was C22:0 (2.14?%). The oil was also found to contain high levels of β-sitosterol (51.93?%), campestanol (21.98?%), and brassicasterol (12.35?%). α-, γ-, and δ-Tocopherols were detected up to levels of 7.67, 125.04, and 3.99?mg/kg, respectively. The induction period (at 110?°C and 20?l/h) of the oil was 8.83?h. The relative position of fatty acids in C₁ and C₃ position was as follows: linoleic 0.45?%, oleic 8.84?%, and erucic 90.72?%. The thermal profile of the oil presented a single peak at ?20.94?°C.     

Natural gas based hydrogen production with zero carbon dioxide emissions

A novel process flowsheet is presented that co-produces hydrogen and formic acid from natural gas, without emitting any carbon dioxide. The principal technologies employed in the process network include combustion, steam methane reforming (SMR), pressure swing adsorption, and formic acid production from CO₂ and H₂. Thermodynamic analysis provides operating limits for the proposed process, and the use of reaction clusters leads to the synthesis of a feasible process flowsheet. Heat and power integration studies show this flowsheet to be energetically self-sufficient through the use of heat engine and heat pump subnetworks. Operating cost/revenue studies, using current market prices for natural gas, hydrogen and formic acid, identify the proposed design’s operating revenue to cost ratio to be 9.29.     

Graphene fluoride: a stable stoichiometric graphene derivative and its chemical conversion to graphene

Stoichoimetric graphene fluoride monolayers are obtained in a single step by the liquid-phase exfoliation of graphite fluoride with sulfolane. Comparative quantum-mechanical calculations reveal that graphene fluoride is the most thermodynamically stable of five studied hypothetical graphene derivatives; graphane, graphene fluoride, bromide, chloride, and iodide. The graphene fluoride is transformed into graphene via graphene iodide, a spontaneously decomposing intermediate. The calculated bandgaps of graphene halides vary from zero for graphene bromide to 3.1 eV for graphene fluoride. It is possible to design the electronic properties of such two-dimensional crystals.     

A New Varying-Parameter Design Formula for Solving Time-Varying Problems

Neural Processing Letters - A novel finite-time convergent zeroing neural network (ZNN) based on varying gain parameter for solving time-varying (TV) problems is presented. The model is based on...