Migrating Autonomous Objects in a WAN Environment

Along with the fast progress the interconnection of computer systems makes the need for enterprise-wide distributed solutions grows. These systems have to support hundreds or even thousands of sites located all over the world. The distances between the sites will impose high communication costs on distributed activities thus significantly increasing their response times. This problem can be alleviated through migrating objects to the sites where they are needed. However, migration in such systems cannot be managed globally. Therefore, we present a migration protocol for (autonomous) objects which enables them autonomously to decide whether or not and which site to migrate to, thus making the system self-tuning. We also present two migration strategies objects can use to derive their migration decisions. The first one finds the optimal placement for an object while the second strategy in some cases returns a sub-optimal location but induces lower computation costs. The two strategies are evaluated through benchmarks in a distributed system of autonomous objects. The experiments show a significant decrease in communication costs when migration is employed.     

Decomposition of phenol by hybrid gas/liquid electrical discharge reactors with zeolite catalysts

Application of hybrid gas/liquid electrical discharge reactors and a liquid phase direct electrical discharge reactor for degradation of phenol in the presence and absence of zeolites have been investigated. Hybrid gas/liquid electrical discharges involve simultaneous high voltage electrical discharges in water and in the gas phase above the water surface leading to the additional OH radicals in the liquid phase and ozone formation in the gas phase with subsequent dissolution into the liquid. The role of applied zeolites, namely NH4ZSM5, FeZSM5 and HY, were also studied. Phenol degradation and production of primary phenol by-products, catechol and hydroquinone, during the treatment were monitored by HPLC measurements. The highest phenol removal results, 89.4-93.6%, were achieved by electrical discharge in combination with FeZSM5 in all three configurations of corona reactors. These results indicate that the Fenton reaction has significant influence on overall phenol removal efficiency in the electrical discharge/FeZSM5 system due to the additional OH radical formation from hydrogen peroxide generated by the water phase discharge.     

Treatment of Chlorophenols by UV-Based Processes: Correlation of Oxidation By-Products, Wastewater Parameters, and Toxicity

The aim of the study was to evaluate the toxicity and biodegradability of para-chlorophenol (p-CP) model wastewater when treated by UV and UV/H2O2 processes. We investigated the correlations between the toxicity and the concentration of p-CP and its oxidation by-products, as well as other parameters—summarizing characteristics which potentially indicate hazardous water components, e.g., AOX (adsorbable organic halides), TOC (total organic carbon), and COD and BOD5 (chemical and biochemical oxygen demand). Biodegradability is estimated by the BOD5/COD ratio. The toxic effects were investigated on luminescent bacteria Vibrio fischeri, determining the EC50 value. The correlation between each data pair was estimated using a statistical approach calculating the Spearman rank coefficients. The biodegradability of the p-CP model wastewater was improved by the UV/H2O2 process; the BOD5/COD ratio increased from 0.37 to 0.73 after a 1-h treatment (F = 1243??mJ?cm-2). According to the calculated Spearman rank coefficient, the highest correlation with toxicity data among all monitored parameters was obtained for hydroquinone and benzoquinone, as by-products of p-CP degradation, as well as for the BOD5/COD ratio.     

Characterization of Mg-substituted hydroxyapatite synthesized by wet chemical method

Mg-substituted hydroxyapatite made up of needle-like and plate-like particles containing different amounts of Mg (between 0.21 wt% and 2.11 wt%) were prepared via wet chemical precipitation method of a homogenous suspension of Mg(OH)₂/Ca(OH)₂ and an aqueous solution of H₃PO₄. According to the data of Brunauer–Emmett–Teller method and field emission scanning electron microscopy, high specific surface area Mg-substituted hydroxyapatite was obtained. Specific surface area of as-synthesized powders increased from 94.9 m² g⁻¹ to 104.3 m² g⁻¹ with increasing concentration of Mg up to 0.64 wt%. Fourier transform infrared spectroscopy, X-ray powder diffraction, differential thermal analysis, and heating microscopy, were used to evaluate thermal stability and sintering behavior of synthesis products. Increase in concentration of Mg in synthesis products (≥0.83 wt%) promoted decomposition of Mg-substituted hydroxyapatite to Mg-substituted β-tricalcium phosphate after thermal treatment.     

Measuring the refractive state of an eye based on the intensity of the retinal reflex

When examining the fundus of the eye with an ophthalmoscope, the intensity of the retinal reflex depends on the refractive state of the eye. In this study, application of this phenomenon for measuring the refractive state of the eye is demonstrated. First, a calibration curve relating the intensity of the retinal reflex and the refractive state was obtained using a model eye. Next, the intensity of the retinal reflex was measured while subjects were viewing a checker-board pattern, the distance of which was varied within the range from 0.17 to 1 m. Further, the relation between the refractive state and the optical power of the stimulus could be determined based on the measured light intensity and the calibration curve. Generally, the measured refractive state increased with the optical power of the stimulus. However, blinking and fluctuations in accommodation had undesired effects on the results.     

Evaluation of atrazine degradation in UV/FeZSM-5/H2O2 system using factorial experimental design

Degradation of atrazine in model wastewater by UV/FeZSM-5/H₂O₂ system chosen as optimal for application of advanced oxidation process (AOP) has been studied in a batch photo reactor. The statistical study of the process was performed using two-level full factorial experimental design with the three process parameters. Individual parameters and their interaction effects on atrazine degradation were determined and statistical model of process was developed. The optimal operating conditions were established. This approach has also given a broader insight of the processes that were occurring in the reaction system, and it has finally led to simplification in terms of kinetics. Atrazine degradation was described by pseudo-first-order kinetics with observed rate constant k′ = 2 × 10⁻³ s⁻¹.     

Photooxidation of benzene-structured compounds: influence of substituent type on degradation kinetic and sum water parameters

The combined influence of substituent type and UV/H₂O₂ process parameters on the degradation of four aromatic water pollutants was investigated using modified 3³ full factorial design and response surface methodology. Degradation kinetics was described by the quadratic polynomial model. According to the applied ANOVA, besides pH and [H₂O₂], model terms related with the pollutant structure are found to be significant. Different optimal operating conditions and values of observed degradation rate constants were determined for each of the pollutants indicating that the type of substituent influences the overall process effectiveness over structurally defined degradation pathway. Biodegradability (BOD₅/COD) and toxicity (TU) were evaluated prior to the treatment and at the reference time intervals t_1/2(P), t_3/4(P), t_1/4(OC) and t_1/2(OC) corresponding to the real time required to reduce the concentration of parent pollutant and organic content for 1/2, 3/4, 1/4 and 1/2 of initial amount. The observed differences are correlated to the structural differences of studied aromatics.     

Microstructure and Toughness of Seeded Hot-Pressed Si3N4 Ceramics

Densification, phase transformation and fracture toughness were studied in hot-pressed Si_3N_4 seeded by in-houseproduced large, elongated β-Si_3N_4 seeds. A mixture of Y_2O_3-Al_2O_3 was used as the sintering aid. Concentration ofseeds were varied from 0 to 6 wt pct and the sintering time at 1700℃ was varied from 1 to 4 h. Maximum fracturetoughness of 9.0 MPam~(1/2) was measured in samples containing 5 wt pct seeds, hot pressed at 1700℃ for 4 h.     

Determination of mineral contents of semimembranosus muscle and liver from pure and crossbred pigs in Vojvodina (northern Serbia)

The content of phosphorous (P), potassium (K), sodium (Na), magnesium (Mg), calcium (Ca), zinc (Zn), iron (Fe), copper (Cu) and manganese (Mn) was investigated in the M. semimembranosus and liver of 69 pigs from 10 different genetic lines, produced in Vojvodina (northern Serbia). Phosphorous was determined by the standard spectrophotometric method. Metals were determined by the flame atomic absorption spectrometry after mineralisation by dry ashing. The difference in the mineral content among the different genetic lines of pigs, reared under the same conditions, was not significant (P > 0.05) in the analysed muscle and liver tissues. The order of the minerals in the meat samples and their content ranges in mg/100 g was K (214–328, on average 280) > P (200–263, on average 225) > Na (39.0–82.7, on average 59.8) > Mg (24.4–29.4, on average 26.6) > Ca (9.8–15.5, on average 11.8) > Zn (2.30–3.29, on average 2.70) > Fe (1.00–2.79, on average 1.42) > Cu (0.18–0.49, on average 0.32) > Mn (0.018–0.038, on average 0.025). Likewise, the order of the minerals in the liver samples and their content ranges in mg/100 g was P (336–448, on average 383) > K (156–306, on average 217) > Na (56.1–126.3, on average 82.2) > Mg (20.8–36.6, on average 25.7) > Ca (15.9–31.1, on average 20.4) > Fe (16.65–30.93, on average 21.78) > Zn (6.32–15.99, on average 9.82) > Cu (0.72–3.06, on average 1.61) > Mn (0.23–0.51, on average 0.35). A higher content of K and Mg was found in the muscle than in the liver tissue, with a highly significant difference for K (P < 0.001). The contents of P, Na, Ca, Zn, Fe, Cu and Mn were significantly higher (P < 0.001) in the liver tissue than those in the muscle tissue. The Vojvodian pork meat showed higher Cu and Mn contents, while the Vojvodian pork liver showed a higher Ca content compared with the values found in other countries.