A machine learning approach for the condition monitoring of rotating machinery

Rotating machinery breakdowns are most commonly caused by failures in bearing subsystems. Consequently, condition monitoring of such subsystems could increase reliability of machines that are carrying out field operations. Recently, research has focused on the implementation of vibration signals analysis for health status diagnosis in bearings systems considering the use of acceleration measurements. Informative features sensitive to specific bearing faults and fault locations were constructed by using advanced signal processing techniques which enable the accurate discrimination of faults based on their location. In this paper, the architecture of a diagnostic system for extended faults in bearings based on neural networks is presented. The multilayer perceptron (MLP) with Bayesian automatic relevance determination has been applied in the classification of accelerometer data. New features like the line integral and feature based sensor fusion are introduced which enhance the fault identification performance. Vibration feature selection based on Bayesian automatic relevance determination is introduced for finding better feature combinations.     

Lipid and protein oxidation of α-linolenic acid-enriched pork during refrigerated storage as influenced by diet supplementation with olive leaves (Olea europea L.) or α-tocopheryl acetate

The objective of this study was to evaluate the effect of diet supplementation with olive leaves or α-tocopheryl acetate on lipid and protein oxidation of raw and cooked n-3 enriched-pork during refrigerated storage. Enrichment of pork with α-linolenic acid through diet supplementation with linseed oil enhanced (p≤0.05) lipid oxidation in both raw and cooked chops but had no effect (p>0.05) on protein oxidation during refrigerated storage while decreasing (p≤0.05) the sensory attributes of cooked pork. Diet supplementation with olive leaves or α-tocopheryl acetate had no effect (p>0.05) on the fatty acid composition of pork but decreased (p≤0.05) lipid oxidation while exerting no effect (p>0.05) on protein oxidation in both raw and cooked α-linolenic acid-enriched chops stored and chilled for 9days. Moreover, olive leaves and α-tocopheryl acetate supplemented at 10g/kg and 200mg/kg diet, respectively, exerted (p≤0.05) a beneficial effect on the sensory attributes of cooked α-linolenic acid-enriched pork chops.     

Fatty acid profile of wild and farmed gilthead sea bream (Sparus aurata)

Historically farmed fish were frequently found to exhibit a lower ratio of n3/n6 fatty acids compared to wild fish. This study compares the proximate and fatty acid composition of wild and cultured gilthead sea bream fish from a lagoon in NW Greece. Wild fish contained less fat and showed different fatty acid profiles. Farmed fish exhibited threefold higher concentrations of linoleic acid (C18:2n-6) in muscle and twofold in visceral fat. Their muscle tissue contained higher levels of saturated fatty acids and higher ratios of eicosapentaenoic acid/docosahexaenoic acid (0.49 ± 0.04 vs. 0.03 ± 0.01; Ρ < 0.001). Wild fish exhibited lower levels of muscle n-3 fatty acids (15.87 ± 0.82 vs. 19.89 ± 1.06; P < 0.001) but a higher ratio of n-3/n-6 (2.22 ± 0.14 vs. 1.64 ± 0.10, Ρ < 0.001). These results emphasize the need to further explore dietary manipulation of fatty acid content as a method of improving the fatty acid profile and maximise the health benefits of consuming farmed fish.     

Social Networks as Trojan Horses to Challenge the Dominance of Existing Hierarchies: Knowledge and Learning in the Water Governance of Volos, Greece

In context of the implementation of the EU Water Framework Directive, conventional hierarchies and dominant logics in the metropolitan area of Volos, Greece, are challenged indirectly, in a “Trojan-horse” like way. The basic characteristic of the water sector in Volos Urban Area is the absolute dominance of centralized services (Municipal Enterprise for Water and Sewage). However, the intense interest of new actors (private companies, NGOs, University and Research Institutes, etc.) has led to the establishment of an informal and voluntary social network. The paper evaluates the role of an informal social network as a new form of governance in the framework of spatial development that has emerged in the shadow of an existing hierarchy. The basic issues highlighted are:

• The challenge to hierarchical decision making structures in the water sector through an informal and voluntary social network.
• The learning processes and knowledge forms that new actors bring to and acquire in such forms of network practices (e.g. contribution to public awareness, mobilisation of local knowledge).

     

Association control algorithms for handoff frequency minimization in mobile wireless networks

As mobile nodes roam in a wireless network, they continuously associate with different access points and perform handoff operations. Frequent handoffs performed by a mobile device may have undesirable consequences, as they can cause interruptions for interactive applications and increase the energy usage of mobile devices. While existing approaches to this issue focus entirely on improving the latency incurred by individual handoffs, in this paper, we initiate a novel approach to association control of mobile devices with the goal of reducing the frequency of handoffs for mobile devices. We study the handoff minimization problem across multiple dimensions: offline versus online where the complete knowledge of mobility patterns of users is known in advance or unknown respectively; capacity constrained versus unconstrained access points, which imposes limits on the number of mobile devices which could be associated with a given access point at any given point in time; group mobility versus arbitrary mobility of users, which are contrasting ways to model the mobility patterns of the mobile users. We consider various combinations of the above dimensions and present the following: (1) optimal algorithms, (2) provably-good online and offline approximation algorithms, (3) complexity (NP-Completeness) results, and (4) a practical heuristic which is demonstrated to work well on real network traces.     

High-level customization framework for application-specific NoC architectures

Network-on-Chip (NoC) has been recognized as the new paradigm to interconnect and organize a high number of cores. NoCs address global communication issues in System-on-Chips (SoC) involving communication-centric design and implementation of scalable communication structures evolving application-specific NoC design as a key challenge to modern SoC design. In this paper we present a SystemC customization framework and methodology for automatic design and evaluation of regular and irregular NoC architectures. The presented framework also supports application-specific optimization techniques such as priority assignment, node clustering and buffer sizing. Experimental results show that generated regular NoC architectures achieve an average of 5.5 % lower communication-cost compared to other regular NoC designs while irregular NoCs proved to achieve on average 4.5×higher throughput and 40 % network delay reduction compared to regular mesh topologies. In addition, employing a buffer sizing algorithm we achieve a reduction in network’s power consumption by an average of 45 % for both regular and irregular NoC design flow.     

In vivo anti-atherogenic properties of cultured gilthead sea bream (Sparus aurata) polar lipid extracts in hypercholesterolaemic rabbits

The aim of this study was to investigate whether the fish lipid extracts have in vivo anti-atherogenic properties in hypercholesterolaemic rabbits. Fish oil extracts were obtained from cultured gilthead sea bream (Sparus aurata) and, for the in vivo experiment, 12 healthy male New Zealand rabbits of specific weight and age were used, which were randomly divided into two groups of six animals each and were given specific diets for 45 days. Group A was given an atherogenic diet, while group B was given an atherogenic diet enriched with Gilthead Sea Bream Polar Lipids (GSBPL).     

Kinetics of endoglucanase and endoxylanase uptake by soybean seeds

The uptakes of endoglucanase and endoxylanase by soybean were studied by measuring the fluorescent intensity of a carboxyfluorescein. The disappearance rates of these enzymes from solution were compared with predictions from different models. The Freundlich model provided the best fit for our data. Enzyme concentration in the solution did not change significantly after 11 d, and therefore it was assumed that equilibrium was reached. Average mass transfer coefficient was calculated for both endoglucanase and endoxylanase from the plot of the rate of uptake against (C(l av) -Cl*) and a value of 4 x 10(-5) ms(-1) was obtained. K value was used to calculate the effective diffusivities of the two enzymes assuming a slice. It is found that K was asymptotic with long residence times, and a value of 4.8 x 10(-10) m2 s(-1) was obtained.     

Growth of Aeromonas hydrophila in the whey cheeses Myzithra, Anthotyros, and Manouri during storage at 4 and 12 degrees C

The fresh whey cheeses Myzithra, Anthotyros, and Manouri were inoculated with Aeromonas hydrophila strain NTCC 8049 (type strain) or with an A. hydrophila strain isolated from food (food isolate) at levels of 3.0 to 5.0 x 10(2) CFU/g of cheese and stored at 4 or 12 degrees C. Duplicate samples of cheeses were tested for levels of A. hydrophila and pH after up to 29 days of storage. At 4 degrees C, A. hydrophila grew in Myzithra and Anthotyros with a generation time of ca. 19 h, but no growth was observed in Manouri. In Myzithra, average maximum populations of 8.87 log CFU/g (type strain) and 8.79 log CFU/g (food isolate) were recorded after 20 and 22 days of storage at 4 degrees C, respectively. The average maximum populations observed in Anthotyros stored at 4 degrees C were 6.72 log CFU/g (food isolate) and 6.13 log CFU/g (type strain) and were observed after 15 and 16 days of storage, respectively. A. hydrophila grew rapidly and reached high numbers in cheeses stored at 12 degrees C. The average generation times were 3.7 and 3.9 h (Myzithra), 4.1 and 6.1 h (Anthotyros), and 8.0 and 9.2 h (Manouri) for the type strain and the food isolate, respectively. Among the different whey cheese trials, the highest A. hydrophila population recorded (10.13 log CFU/g) was in Myzithra that had been inoculated with the food isolate after 8 days of storage at 12 degrees C. To prevent A. hydrophila growth in whey cheeses, efforts must be focused on preventing postprocessing contamination and temperature abuse during transportation and storage.     

Carbon nanotubes encapsulating superconducting single-crystalline tin nanowires

Superconducting low dimensional systems are the natural choice for fast and sensitive infrared detection, because of their quantum nature and the low-noise, cryogenic operation environment. On the other hand, monochromatic and coherent electron beams, emitted from superconductors and carbon-based nanostructured materials, respectively, are significant for the development of electron optical systems such as electron microscopes and electron-beam nanofabrication systems. Here we describe for the first time a simple method which yields carbon nanotubes encapsulating single crystalline superconducting tin nanowires by employing the catalytic chemical vapor deposition method over solid tin dioxide. The superconducting tin nanowires, with diameters 15-35 nm, are covered with well-graphitized carbon walls and show, due to their reduced diameters, a critical magnetic field (Hc) more than 30 times higher than the value of bulk metallic tin.