Thermodynamic analysis of an existing coal-fired power plant for district heating/cooling application

In a conventional coal-fired power plant, which is only designed for electricity generation, 2/3 of fuel energy is wasted through stack gases and cooling water of condensers. This waste energy could be recovered by trigeneration; modifying the plants in order to meet district heating/cooling demand of their locations. In this paper, thermodynamical analysis of trigeneration conversion of a public coal-fired power plant, which is designed only for electricity generation, has been carried out. Waste heat potentials and other heat extraction capabilities have been evaluated. Best effective steam extraction point for district heating/cooling system; have been identified by conducting energetic and exergetic performance analyses. Analyses results revealed that the low-pressure turbine inlet stage is the most convenient point for steam extraction for the plant analyzed.     

Numerical Determination of Thermal-Diffusivity Coefficients of Some Nematic Liquid Crystals <Emphasis Type="Italic">in Situ</Emphasis>

In this study, a new experimental study has been implemented to determine the thermal-diffusivity parameters of industrial nematic liquid crystals, 4-pentyl-4′-cyanobiphenyl (5CB) and 4′-octyl-4-cyanobiphenyl (8CB), both numerically by using the finite difference method (FDM) for forward solutions and experimentally by measuring the temperature variation with time and position. The most important parts of this experimental study are the heating system and the liquid crystal cell, which were constructed in-house to determine the temperatures of the materials in situ. Four different positions for local measurements have been studied, and the optimum graph of this variation has been determined. The experimental and theoretical results of this study are consistent with previous measurements performed by means of a conventional thermal technique.     

Amperometric Simultaneous Measurement of Copper and Cobalt Ions with Polythiophene Incorporating Pendant Terpyridine Groups

Terpyridine containing thiophene monomer was synthesized. Electrochemical behavior of the monomer was studied by cyclic voltammetry. This monomer was polymerized via electrochemical methods and the resultant polymer was characterized. The stepwise fabrication process of the polymeric film electrode and its electrochemical sensing performance towards simultaneously Co and Cu ions were evaluated. The sensing parameters of the polymer electrode were investigated in detail, and the determination conditions were optimized. Under the optimal conditions, sensor response peak is linear to the Co ion concentration in the range of 1.0-50.0 µM and the Cu ion concentration in the range of 1.0–20.0 µM. Detection limit of terpyridine-based polythiophene film electrode for Co and Cu is respectively 100 nM and 0.05 nM.     

Influence of osmolytes on the stability of thylakoid‐based dye‐sensitized solar cells

In recent years, there has been considerable interest in incorporating naturally occurring components of the photosynthetic apparatus into man‐made solar cells, because of the high quantum efficiency of photosynthetic reaction centers. One hurdle to overcome regarding the use of native membranes in these devices is their limited lifespans. In this study, we used stabilizers to increase the long‐term viability of biomolecules in vitro, thereby alleviating this challenge. In this regard, it is known that osmolytes, such as glycine betaine (GB) and sucrose, preserve photosynthetic activity in isolated photosystems. Upon investigation of the thermal protection properties of GB and sucrose in thylakoid‐based dye‐sensitized solar cells, we report that the addition of GB and sucrose to the thylakoid photosensitizer maintains nonzero photocurrent in the thylakoid‐based solar cell upon heating to 50°C. At 50°C, the GB‐containing cell displayed about a fourfold increase in photocurrent than the control cell, in which the photocurrent was decreased to nearly zero. The addition of 0.5M and 1M sucrose has respectively caused nearly 40% and 70% increases in photoinduced electron transfer activity over the control at 35°С. Similarly, though to a lesser extent, 1M GB caused an approximate 40% increase in electron transfer activity as well. Moving forward, this approach will be extended to alternative membrane protein isolation strategies, allowing for an accurate comparison with traditional detergent‐isolated complexes, with the ultimate goal of developing a cost‐effective and sustainable solar cell.     

Investigation of Arsenic and Cadmium Contents in Rice Samples in Turkey by Electrothermal Atomic Absorption Spectrometry

Electrothermal atomic absorption spectrometry was the method used for the direct determination of arsenic and cadmium traces in rice samples. The optimum experimental conditions were investigated in the presence of a Pd/Mg(NO₃)₂ modifier. For arsenic and cadmium, the detection limits were 6.1 and 0.7 μg?kg^?1, whereas the characteristic concentrations were 1.33 and 0.067 μg?L^?1, respectively. For the validation of the method, the concentrations of As and Cd in IRMM-804 rice flour and GBW-08503 wheat flour certified reference materials were determined after microwave-assisted digestion of the samples. The results were found within the uncertainty limits of the certified values. The different 25 rice samples sold in Turkey were digested using a microwave system and then analyzed. The average (range) As and Cd concentrations of all samples were 0.0985 (0.0204–0.1708) and 0.0314 (0.0084–0.0775) mg?kg^?1, respectively. The arsenic and cadmium results were at acceptable levels. The average As and Cd amounts taken from rice are below the provisional tolerable weekly intake levels accepted by the World Health Organization. The distribution of analyte concentrations in some selected rice packages was investigated. The concentrations of both analytes were changed in a wide range even in the same packages.     

Crosslinked DADMAC polymers as cationic super absorbents

Loosely crosslinked cationic polyelectrolytes (polyquats) with super-water-sorption abilities are presented, for the first time. Hydrogels obtained by radically initiated copolymerization of N,N-diallyl, N,N-dimethyl ammonium chloride (DADMAC) with N-vinyl 2-pyrrolidone (NVP) in presence of N,N,N′,N′-tetraallyl piperazinium dichloride (TAP) as crosslinker showed reasonably high equilibrium swelling ratios, as high as those for poly(acrylic acid)-based super absorbents.The highest swelling ratios (up to 360) were attained by fully cationic hydrogels derived from DADMAC and 0.5% TAP. The hydrogels with 0.5–5% crosslinkers exhibited rapid expansion in neutral water, so that the equilibrium swelling values were attained within 2–3 min. The crosslinking densities of the gels were estimated by Flory-type swelling model using “phantom network elasticity” for the elastic contribution. This estimation revealed low crosslinking efficiencies of TAP (0.24–0.35) due to its double cationic charge.In the study “the salt effect” and effects of the comonomer ratios and crosslinker contents on the swellings were also investigated.     

Irrigation Management in GAP

The multisectoral Southeastern Anatolia Project (GAP) is the largest regional developmentplan for one of the less developed parts of Turkey. The GAP project includes the irrigation of 1.7 million ha of land and generation of 27 billion kWh of hydroelectric power with an installed capacity of 7500 MW. In order to optimize the benefits to be obtained from irrigation and to ensure sustainable irrigation in the GAP area, the Government of Turkey has commissioned the GAP Management, and Operation Maintenance study (GAP MOM). The overall MOM model provides an institutional and organizational framework that promotes the most effective development of irrigated agriculture in the GAP region. This goal can be expressed as three major objectives: maximize net benefits, ensure sustainability and be implementable and flexible.     

A new relational learning system using novel rule selection strategies

This paper describes a new rule induction system, rila, which can extract frequent patterns from multiple connected relations. The system supports two different rule selection strategies, namely the select early and select late strategies. Pruning heuristics are used to control the number of hypotheses generated during the learning process. Experimental results are provided on the mutagenesis and the segmentation data sets. The present rule induction algorithm is also compared to the similar relational learning algorithms. Results show that the algorithm is comparable to similar algorithms.     

Floc settling characteristics of turbid water coagulated with moringa oleifera seeds

The results of studies into the particle aggregations and settling rates of flocs from turbid water (kaolin suspension) with turbidities varying from 50 to 550 NTU coagulated with Moringa oleifera seeds are presented. The results of the laboratory based study showed that the maximum value of the “apparent aggregation rate”, K _app,increased with increase in initial turbidity. K _app was found to be 0.000778 for low turbidity (50 NTU) and 0.00654 for high turbidity (550 NTU). The velocity gradient for rapid mix at the maximum K _app was found to be constant at 443/sec for all turbidities. Settling rate of floc coagulated with Moringa oleifera seed was dependent on the initial turbidity of the water sample. For water with initial turbidity of 50 NTU, 30% to 70% turbidity was removed between 60 and 210 minutes, while for high turbidity of 400 to 550 NTU, 80% to 95% turbidity removal occurred between 60 and 150 minutes.