Exposure in Wireless Sensor Networks: Theory and Practical Solutions

Wireless ad hoc sensor networks have the potential to provide the missing interface between the physical world and the Internet, thus impacting a large number of users. This connection will enable computational treatments of the physical world in ways never before possible. In this far reaching scenario, Quality of Service can be expressed in terms of accuracy and/or latency of observing events and the overall state of the physical world. Consequently, one of the fundamental problems in sensor networks is the calculation of coverage, which can be defined as a measure of the ability to detect objects within a sensor filed. Exposure is directly related to coverage in that it is an integral measure of how well the sensor network can observe an object, moving on an arbitrary path, over a period of time. After elucidating the importance of exposure, we formally define exposure and study its properties. We have developed an efficient and effective algorithm for exposure calculations in sensor networks, specifically for finding minimal exposure paths. The minimal exposure path provides valuable information about the worst case exposure-based coverage in sensor networks. The algorithm can be applied to any given distribution of sensors, sensor and sensitivity models, and characteristics of the network. Furthermore, it provides an unbounded level of accuracy as a function of run time and storage. Finally, we provide an extensive collection of experimental results and study the scaling behavior of exposure and the proposed algorithm for its calculation.     

Flux recovery of tubular ceramic membranes fouled with whey proteins

Membrane process efficiency is governed by the formation of fouling deposits during processing of dairy fluids. Because of fouling with whey proteins, permeate flux can drastically decline during filtration process. This paper describes the flux recovery procedure for ceramic tubular membranes (50 and 200 nm pore sizes) fouled with whey proteins. The results comprehend the effect of rinsing and cleaning agent choice and concentration, on the cleaning efficiency. As chemical cleaning agents, the caustic solution and the commercial detergents P3-ultrasil 67 and P3-ultrasil 69 were selected. The observations are that rinsing with deionised water contributes to a flux recovery to a certain degree. For the 50 nm membrane, the choice of the 1.0% (w/w) caustic solution, as cleaning agent, gives the best flux recovery. For the 200 nm, total flux recovery was not observed regardless of the cleaning agent choice and concentration. Cleaning with chosen commercial detergent appeared to be less efficient than cleaning with caustic solution for the chosen ceramic membranes. Also, a mathematical model, proposed in this study, has shown high agreement with experimentally obtained data.     

Ozone treatment ameliorates oil sands process water toxicity to the mammalian immune system

We evaluated whether ozonation ameliorated the effects of the organic fraction of oil sands process water (OSPW) on immune functions of mice. Ozonation of OSPW eliminated the capacity of its organic fraction to affect various mouse bone marrow-derived macrophage (BMDM) functions in vitro. These included the production of nitric oxide and the expression of inducible nitric oxide synthase, the production of reactive oxygen intermediates and the expression of NADPH oxidase subunits, phagocytosis, and the expression of pro-inflammatory cytokine genes. Ozone treatment also eliminated the ability of OSPW organic fraction to down-regulate the expression of various pro-inflammatory cytokine and chemokine genes in the liver of mice, one week after oral exposure. We conclude that ozone treatment may be a valuable process for the remediation of large volumes of OSPW.     

Growth of Sb2S3 nanowires synthesized by colloidal process and self-assembly of amorphous spherical Sb2S3 nanoparticles in wires formation

We report the organic synthesis and growth of antimony sulfide (Sb₂S₃) amorphous nanospheres to nanowires via a simple, colloidal synthetic method. Amorphous Sb₂S₃ nanospheres self-assembly in wires formation was dispersed in isopropyl alcohol. With increased heating time, Sb₂S₃ nanospheres grew into Sb₂S₃ nanowires, probably involving both mechanisms of Ostwald-ripening and spherical nanoparticle self-organization through oriented-attachment of individual nanoparticles. Also, the as-synthesized Sb₂S₃ nanowires with different heating times (0, 5 and 10 min.) from the moment of appearance of the Sb₂S₃ precipitate were analyzed. The observed nanowires become longer with increased heating time and are around 100 nm in diameter and 10?C20 ??m in length. UV-Vis absorption spectroscopy reveals that the optical band-gap energy of the Sb₂S₃ nanowires is independent of the heating times and is found to be ??1.5?C1.6 eV. The optical band-gap energy found for amorphous Sb₂S₃ nanospheres was also ??1.5 eV. The structure of Sb₂S₃ samples was refined down to R-factors of 10.82, 11.76 and 12.08%. The refinement showed that Sb₂S₃ powder belongs to the orthorhombic type with space group Pbnm (no. 62) and that Sb₂S₃ nanowires grow along the [010] direction.     

Leakage quantification of compressed air using ultrasound and infrared thermography

With the leakage elimination in compressed air systems, it is possible to save up to 40% of energy. With appropriate inspection and maintenance of compressed air systems, leakage elimination should be a routine. This paper describes and compares two different noncontact methods for compressed air leakage quantification, ultrasound and infrared thermography. The potentials and limitations of these technologies are analyzed, as well as the reliability and accuracy of results thus obtained. From the results presented in this paper, it can be concluded that thermography offers good results for the leakage quantification from the orifices greater than 1.0 mm and ultrasound should be used for leakage detection for all the dimensions of orifices, but for the quantification purposes only for smaller leaks. As a support for leakage quantification, we proposed diagrams of a leak flow as a function of sound level and as a function of detected temperature change.     

Electrochemical and structural study on cycling performance of γ-LiV2O5 cathode

Electrochemical and structural properties of LiV₂O₅ cathode were investigated. Obtained by solid state reaction at high temperature the material crystallized as gamma polymorph phase, γ-LiV₂O₅. The gamma structure provides two crystallographic sites to accommodate lithium ions, Li1 and Li2 position. Lithium insertion at these two sites occurs at two respective voltages versus lithium metal: ~3.6 V (Li1) and ~2.4 V (Li2). Intercalation at Li1 position is reversible in both organic and aqueous electrolyte and provides stable cycling performance at the high voltage. On the contrary, sluggish insertion/removal of Li⁺ at Li2 sites causes unstable performance and significant storage capacity fade at lower voltages. Lithium diffusion 3d landscape was determined by bond valence calculations applied on the γ-LiV₂O₅ phase, as well as on the metastable phases of γ′-V₂O₅ and ζ-Li₂V₂O₅ that exist at high and low voltages respectively. The model was proposed based on inactivity of Li2 position of the metastable ζ-Li₂V₂O₅ phase which provides explanation for the observed storage capacity loss at low voltages.     

Microsized fayalite Fe2SiO4 as anode material: the structure,electrochemical properties and working mechanism

Journal of Electroceramics - Fayalite Fe2SiO4 is synthesized by the solid-state reaction without ball milling. The obtained powder is further structurally and electrochemically examined. Field...     

Dose-dependent immunomodulatory effects of 10-hydroxy-2-decenoic acid on human monocyte-derived dendritic cells

The effect of 10-hydroxy-2-decenoic acid (10-HDA), the unique component of royal jelly, on maturation and functions of human monocyte-derived dendritic cells (MoDCs) in culture was investigated. It has been shown that 10-HDA, at concentrations higher than 500 μM, induces apoptosis of MoDCs. A lower dose (50 μM) stimulated T helper (Th)1 and down-regulated Th2 immune responses, as judged by the levels of interferon-gamma (IFN-γ) and interleukin (IL)-4, respectively, in supernatants of 10-HDA-treated MoDCs cultivated with allogeneic CD4⁺T cells. In contrast, a higher dose of 10-HDA (500 μM), although non-cytotoxic, inhibited maturation of lipopolysaccharide (LPS)-stimulated MoDCs. Such treated MoDCs produced lower levels of IL-12, IL-18 and tumour necrosis factor-alpha (TNF-α) and down-regulated both Th1 and Th2 immune responses. In conclusion, our results suggest that 10-HDA exerts different activity on human MoDCs, depending on applied concentrations, which is important when considering its therapeutic immunomodulatory property.     

Sequential disinfection of cryptosporidium parvum by ozone and chlorine dioxide

A two step disinfection approach was evaluated for control of Cryptosporidium parvum using bench‐scale experiments in 0.05 M phosphate buffer at pH 8 and 22 °C. Sequential application of ozone and chlorine dioxide was evaluated where ozone was applied first followed by chlorine dioxide. Infectivity in neonatal CD‐1 mice was used to assess oocyst viability after disinfection. The sequential treatment of oocysts by ozone followed by chlorine dioxide resulted in additional inactivation of C. parvum due to the synergism of the two disinfectants. The inactivation kinetics for chlorine dioxide were modeled following preconditioning with ozone at a given level using the Integral‐Hom model which takes the disinfectant decay into account. These preliminary findings indicate that sequential disinfection with ozone followed by chlorine dioxide may have potential in controlling waterborne parasites.