Hexavalent chromium removal by ferrochromium slag

The aim of this study is to demonstrate the potential of Cr(VI) generation during jigging operation applied for ferrochrome recovery from slag. The Cr(VI) concentrations of water contacted with ferrochromium slag (W/FS=10) in a closed cycle after 50 batches were found as 0.61 mg/l. Also, reduction of Cr(VI) to Cr(III) and a subsequent precipitation of Cr(III) by using ferrochrome slag (FS) in a model solution has been aimed. The effects of amount of acid, contact time, FS dosage, initial Cr(VI) concentration and temperature on the Cr(VI) reduction have been studied through the batch runs. The amount of acid has been found to be the most effective parameter affecting the Cr(VI) reduction. A 10 g/l FS dosage and 3.5 ml/l H2SO4 (5M) are sufficient to reduce all Cr(VI) in the model solution containing 10mg/l Cr(VI) and for contact time of 60 min at 25 degrees C. In reduced solutions, precipitation of metal ions has been studied by using extra FS. A 60 g/l dosage of fresh FS can precipitate all Cr(III) and Fe ions in the reduced solution. Thus, it has been demonstrated that the treatment of jigging water stream to be generated in a ferrochrome plant containing Cr(VI) can be accomplished by using ferrochromium slag and sulphuric acid. Also, it has been determined that solid residues of the process are environmentally stable by applying TCLP test.     

KINETICS FOR FAST PYROLYSIS OF HAZEL NUT SHELL

In this article, the potential utilization of hazel nut shell as a combustible residue was studied. To obtain liquid and gaseous products, the hazel nut shell was subjected to pyrolysis and it was converted to 49.3 % (w) gaseous and 20.0 % (w) liquid products at 475 °C for 7.5 minutes in a simple pyrolysis device The kinetic model used in the present study was based on fractional weight loss for each pyrolysis step. The simple fast pyrolysis was compared with TGA technique.     

User QoE Influenced Spectrum Trade,Resource Allocation,and Network Selection

In future wireless networks, we envision more dynamic telecommunication paradigm, where the dynamics may be translated into dynamic service offerings and user profiles etc. We further expect that the wireless communication market will be influenced when the user-centric network selection vision is realized. By the user-centric network selection vision, we mean that users will be free to select any available network operator or service provider on short term contractual basis. This dictates that operators will compete for their share of a common user pool on much smaller time quanta when compared with the current long term user contacts with the operators. One intuitive strategy of operators will be to incentivize users by offering different QoS and service price offers. As the operators’ offers are influenced by their incurring costs. This necessitates to study the market behavior at different levels and investigate the operator and user behavior at these level. In this paper, we categorize and position the communication players and model the interaction between players at different levels. We introduce the learning aspects in the interaction and investigate the equilibrium strategies of involved stake-holders i.e., users and operators. We also model the utility functions of all the involved stake-holders. We also examine the risk-sensitive utility functions in order to cover both risk-seeking and risk-averse in the user QoEs. We implement the user-centric approach and compare it against our proposed network-centric resource utilization and call blocking.     

Effects of starch loading rate on performance of combined fed-batch fermentation of ground wheat for bio-hydrogen production

Ground wheat powder solution (10 g L⁻¹) was subjected to combined dark and light fermentations for bio-hydrogen production by fed-batch operation. A mixture of heat treated anaerobic sludge (AN) and Rhodobacter sphaeroides-NRRL (RS-NRRL) were used as the mixed culture of dark and light fermentation bacteria with an initial dark/light biomass ratio of 1/2. Effects of wheat starch loading rate on the rate and yield of bio-hydrogen formation were investigated. The highest cumulative hydrogen formation (CHF = 3460 ml), hydrogen yield (201 ml H₂ g⁻¹ starch) and formation rate (18.1 ml h⁻¹) were obtained with a starch loading rate of 80.4 mg S h⁻¹. Complete starch hydrolysis and glucose fermentation were achieved within 96 h of fed-batch operation producing volatile fatty acids (VFA) and H₂. Fermentation of VFAs by photo-fermentation for bio-hydrogen production was most effective at starch loading rate of 80.4 mg S h⁻¹. Hydrogen formation by combined fermentation took place by a fast dark fermentation followed by a rather slow light fermentation after a lag period.     

What determines urban households’ willingness to pay for CO2 emission reductions in Turkey: A contingent valuation survey

This paper explores Turkish urban households’ willingness to pay (WTP) for CO₂ emission reductions expected to result from improvements in power production. A face-to-face questionnaire, with a Contingent valuation (CV) module prepared using the double-bounded dichotomous choice elicitation framework, was administered to 2422 respondents representative of urban Turkey—a developing country with low but rapidly increasing greenhouse gas emissions. The determinants of WTP were identified by considering not only the impact of standard socio-economic factors but also the effects of environmental knowledge, attitudes and behaviour, the relevance of the identity of the collection agent (national versus international institutions) in terms of trust people have towards them, and the degree of perceived participation of others in the realization of the project. Our study confirms the existing literature in demonstrating that WTP figures reported by young and educated people that are active on environmental issues, and who also possess material security and environmental knowledge, are more likely to be high. However, their willingness to make contributions is hampered significantly by their belief that their fellow citizens will not contribute and the general lack of trust in institutions. Overall, this study may be taken as a call to eliminate governance-related uncertainties in climate change deals.     

Comparison of different electrodes in hydrogen gas production from electrohydrolysis of wastewater organics using photovoltaic cells (PVC)

Electrical power generated by a photovoltaic cell (PVC) was supplied to diluted industrial wastewater in a mechanically mixed and sealed stainless-steel reactor for hydrogen gas production. Three different electrodes, graphite, stainless steel and aluminum rods were used for comparison. Protons released from decomposition of organic compounds and electrons provided by the DC current reacted to form hydrogen gas. The highest cumulative hydrogen gas formation (CHF) was obtained with the aluminum electrode (120 L in 8 days) and the lowest was with the graphite electrode (4 L). Hydrogen gas production from wastewater was 2.4 times higher than that produced from water when aluminum electrodes were used. TOC content of wastewater was reduced from 2400 to 1700 mg L⁻¹ with nearly 29% TOC removal within 6 days. CHF from wastewater was 76 L within 18 days with the stainless-steel electrodes while CHF from water was only 9.5 L. Fermentative hydrogen gas production from wastewater was negligible in the absence PVC. Energy conversion efficiency for hydrogen gas production (hydrogen energy/electric energy) was found to be 74% with the aluminum electrodes.     

Performance evaluation of evolutionary heuristics in dynamic environments

In recent years, there has been a growing interest in applying genetic algorithms to dynamic optimization problems. In this study, we present an extensive performance evaluation and comparison of 13 leading evolutionary algorithms with different characteristics on a common platform by using the moving peaks benchmark and by varying a set of problem parameters including shift length, change frequency, correlation value and number of peaks in the landscape. In order to compare solution quality or the efficiency of algorithms, the results are reported in terms of both offline error metric and dissimilarity factor, our novel comparison metric presented in this paper, which is based on signal similarity. Computational effort of each algorithm is reported in terms of average number of fitness evaluations and the average execution time. Our experimental evaluation indicates that the hybrid methods outperform the related work with respect to quality of solutions for various parameters of the given benchmark problem. Specifically, hybrid methods provide up to 24% improvement with respect to offline error and up to 30% improvement with respect to dissimilarity factor by requiring more computational effort than other methods.     

Adaptive anti-spam filtering for agglutinative languages: a special case for Turkish

We propose anti-spam filtering methods for agglutinative languages in general and for Turkish in particular. The methods are dynamic and are based on Artificial Neural Networks (ANN) and Bayesian Networks. The developed algorithms are user-specific and adapt themselves with the characteristics of the incoming e-mails. The algorithms have two main components. The first one deals with the morphology of the words and the second one classifies the e-mails by using the roots of the words extracted by the morphological analysis. Two ANN structures, single layer perceptron and multi-layer perceptron, are considered and the inputs to the networks are determined using binary model and probabilistic model. Similarly, for Bayesian classification, three different approaches are employed: binary model, probabilistic model, and advanced probabilistic model. In the experiments, a total of 750 e-mails (410 spam and 340 normal) were used and a success rate of about 90% was achieved.     

Advanced Oxidation of Diuron by Photo-Fenton Treatment as a Function of Operating Parameters

Advanced oxidation of diuron in aqueous solution by photo-Fenton treatment was investigated by batch experiments. Effects of operating parameters, namely, the concentrations of pesticide (diuron), hydrogen peroxide (H2O2), and ferrous ion [Fe (II)] on oxidation of diuron were investigated by using Box-Behnken statistical experiment design and the response surface methodology. Diuron oxidation by photo-Fenton treatment was evaluated by determining the total organic carbon (TOC), diuron, and adsorbable organic halogen (AOX) removals. Concentration ranges of the reagents resulting in the highest level of diuron oxidation were determined. Diuron removal increased with increasing H2O2 and Fe (II) concentrations, up to a certain level. H2O2 concentration had a more profound effect than diuron and Fe (II) on removal of diuron, TOC, and AOX from the aqueous solution. Complete (100%) disappearance of diuron was achieved after a 15?min reaction period. However, 85% of diuron was mineralized after 240?min, indicating a low level of intermediate formation. Optimal H2O2/Fe (II)/diuron ratio resulting in maximum diuron (100%), TOC (85%), and AOX (100%) removals was found to be 267/36/25?(mg?L?1).     

Intrauterine growth restriction (IUGR) risk decision based on support vector machines

This paper studies the risk of intrauterine compromise in the fetuses with intrauterine growth restriction (IUGR) using support vector machines (SVM). A structured and globally optimized SVM system may be preferable procedure in the identification of IUGR fetus at risk. The IUGR risk is estimated in two stages: In the first stage, noninvasive Doppler pulsatility index (PI) and resistance index (RI) of umbilical artery (UA), middle cerebral artery (MCA) and ductus venosus (DV), and amniotic fluid index (AFI) are retrospectively analyzed and the Doppler indices are applied to the SVM system to make a diagnosis decision on the fetal well being as “reactive” or “nonreactive and/or fetal distress (FD)” on the nonstress test (NST) (training data). In the second stage (testing data), the decision is validated by the NST (target value). Experiments are performed in retrospective clinical situation. Forty-four preterm with IUGR and without IUGR pregnancies before 34 weeks gestation are considered. Also, the nonparametric Bayes-risk decision rule, k-nearest neighbor (k-NN), is used for comparison. It is observed that the SVM system is proven to be useful in predicting the expected risk in IUGR cases in the small population study. Also, the PI and RI values of UA, MCA and DV are effective in distinguishing IUGR cases at risk.