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.     

Hydrogen gas production from cheese whey powder (CWP) solution by thermophilic dark fermentation

Hydrogen gas production from cheese whey powder (CWP) solution by thermophilic dark fermentation was investigated at 55 °C. Experiments were performed at different initial total sugar concentrations varying between 5.2 and 28.5 g L⁻¹ with a constant initial bacteria concentration of 1 g L⁻¹. The highest cumulative hydrogen evolution (257 mL) was obtained with 20 g L⁻¹ total sugar (substrate) concentration within 360 h while the highest H₂ formation rate (2.55 mL h⁻¹) and yield (1.03 mol H₂ mol⁻¹ glucose) were obtained at 5.2 and 9.5 g L⁻¹ substrate concentrations, respectively. The specific H₂ production rate (SHPR = 4.5 mL h⁻¹ g⁻¹cells) reached the highest level at 20 g L⁻¹ total sugar concentration. Total volatile fatty acid (TVFA) concentration increased with increasing initial total sugar content and reached the highest level (14.15 g L⁻¹) at 28.5 g L⁻¹ initial substrate concentration. The experimental data was correlated with the Gompertz equation and the constants were determined. The optimum initial total sugar concentration was 20 g L⁻¹ above which substrate and product (VFA) inhibitions were observed.     

Rotating-Perforated-Tubes Biofilm Reactor for High-Strength Wastewater Treatment

A rotating-perforated-tubes biofilm reactor was used for treatment of synthetic wastewater at different operating conditions. The biofilm reactor consisted of two sections each having 25 perforated tubes mounted on three perforated discs. The battery of the tubes was rotated with the aid of a shaft and a motor. Effects of major process variables such as feed wastewater flow rate and COD concentration on the system performance were investigated. Kinetics of COD removal was investigated and kinetic constants determined by using the experimental data. An empirical design equation was developed to quantify the system's performance as a function of major process variables.     

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.     

Aircraft Sensor and Actuator Fault Detection, Isolation, and Accommodation

The purpose of the paper is to present an approach to detect, isolate, and accommodate the aircraft sensor and actuator faults using unknown input observers (UIOs). Full-order observers, reduced-order observers, and UIOs are widely used in state estimations. After the estimation of states, fault detection can be provided by conducting residual analysis. Despite of the existence of unknown inputs, fault detection and isolation are implemented for a very large, four-engined, cargo jet aircraft model. Sensor accommodation is realized via switching under redundant sensor existence assumption. Actuator accommodation is provided by gain scheduling. Hence, if a fault occurs in an actuator corresponding to the control surfaces, the remainder (n?1) actuators are used to avoid hazardous flight. Sensor and actuator faults are detected by using residuals. Sensor faults are effective on the outputs, while actuator faults are effective on the state equations. Fault isolation is implemented by taking into account that each residual is sensitive to all of the other faults but one fault. Fault detection, isolation, and a recommended accommodation are shown through the simulations to be functional.     

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.     

Investigation of mechanical and creep properties of polypyrrole by depth-sensing indentation

In this study, we used depth-sensing indentation (DSI) technique to investigate some mechanical properties (reduced elastic modulus, indentation hardness, and creep) of polypyrrole (PPy) conducting polymer obtained with different support electrolyte concentration. The influence of support electrolyte concentration on these parameters was also determined. The order of doping degree of the samples was determined by cyclic voltammetry. The indentation load–displacement curves of the samples were obtained under different peak load levels with a 70 s holding time at maximum load. Reduced elastic modulus and hardness values were determined by analysis of these curves using the Feng–Ngan (F–N) and Tang–Ngan (T–N) methods, respectively. Both reduced elastic modulus (E _r) and indentation hardness (H) exhibited significant peak load dependence, i.e., indentation size effect (ISE). It was found that both E _r and H values decreased as the support electrolyte concentration was increased. This was explained by an increase in the free volume as the doping degree was raised. The creep behavior of the samples was monitored from the load holding segment of the load–unload curves. It was found that creep increases with the increasing support electrolyte concentration.     

A Comparative Study on Response Surface Optimization of Supercritical Fluid Extraction Parameters to Obtain Portulaca Oleracea Seed Oil with Higher Bioactive Content and Antioxidant Activity Than Solvent Extraction

Portulaca oleracea (purslane) seed oil is a rich source of omega-6 and omega-3 fatty acids. Extraction of the purslane seed oil while preserving its high nutritive quality has been a challenge since conventional solvent extraction has many adverse effects on bioactive content. This study aims the optimization of purslane seed oil supercritical fluid extraction (SFE) conditions and to compare purslane seed oils obtained with SFE and conventional solvent extraction in terms of oil yield, along with the purslane seed oil quality and bioactive content. For this purpose, the SFE process parameters (pressure, temperature, static time, and dynamic time) are optimized for oil yield, omega-6, omega-3, and antioxidant activity using response surface methodology (RSM). Optimum SFE pressure, temperature, static time, and dynamic time levels are determined as 350 bar, 50 °C, 20 min, and 90 min, respectively. Oil yield and physicochemical quality properties of conventional solvent extract and SFE samples are determined and compared. Consequently, samples obtained via SFE and solvent extraction have similar quality properties. Distinctly, SFE allows an extraction with 5.6% higher total phenolic compound (TPC) and 33% higher antioxidant activity than solvent extraction. Practical Applications: In the study, the extraction of purslane oil using supercritical fluid extraction is optimized with different approaches. At optimum conditions, purslane oil is extracted and all physicochemical properties and the process efficiency (yield) are compared with the solvent-extracted samples. The results of this study make supercritical fluid extraction of purslane seed oil possible since all optimum operating conditions of a pilot-sized extractor are reported in the study. It is believed that the results provide a good starting point for industrial operations. Moreover, researchers also believe that research studies unveiling the new potential oil-bearing seeds are important to overcome the vegetable oil shortage that emerged this year.     

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.