Monitoring of energy exergy efficiencies and exergoeconomic parameters of geothermal district heating systems (GDHSs)

In this work, the monitoring energy and exergy efficiency results of the last heating seasons of operation of the geothermal district heating systems (GDHSs) and their technical availability analysis and monitoring exergoeconomic parameters are presented. The case studies cover the actual system data taken from the systems in Afyon and Salihli GDHSs, Turkey. General energy, exergy, technical availability, and exergoeconomic analysis of the GDHSs are introduced. Furthermore, the average technical availability, real availability, capacity factor and energy and exergy efficiencies value of GDHSs have been analyzed.     

Real‐time temperature and photon transmission measurements for monitoring phase separation during the formation of poly(N‐isopropylacrylamide) gels

Phase separation during the formation of poly(N‐isopropylacrylamide) (PNIPA) hydrogels was investigated using real‐time photon transmission and temperature measurements. The hydrogels were prepared by free‐radical crosslinking polymerization of N‐isopropylacrylamide (NIPA) in the presence of N,N′‐methylenebisacrylamide (BAAm) as a crosslinker in an aqueous solution. The onset reaction temperature T₀ was varied between 20 and 28°C. Following an induction period, all the gelation experiments resulted in exothermic reaction profiles. A temperature increase of 6.5 ± 0.6°C was observed in the experiments. It was shown that the temperature increase during the formation and growth process of PNIPA gels is accompanied by a simultaneous decrease in the transmitted light intensities I_tr. The decrease in I_tr at temperatures below the lower critical solution temperature of PNIPA was explained by the concentration fluctuations due to the inhomogeneity in the gel network. At higher temperatures, it was shown that the gel system undergoes a phase transition via a spinodal decomposition process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3589–3595, 2002     

Thermodynamic performance analysis of a copper–chlorine thermochemical cycle and biomass based combined plant for multigeneration

The primary objective of this work is to investigate a comprehensive thermodynamic assessment of the biomass-assisted multigeneration plant for electrical energy, hydrogen, heating-cooling, drying, and hot water production. The suggested multigeneration plant includes the biomass gasification process, Brayton cycle, Kalina cycle, organic Rankine cycle, and cascade refrigeration plant, which is to produce heating and cooling loads, drying system, hydrogen generation with copper–chlorine thermochemical process, and hydrogen liquefaction process. Based on the thermodynamic laws, the total irreversibility rate and performance assessment of the examined study is conducted. Moreover, the impact of various factors such as reference temperature, biomass gasifier temperature, and mass flow rate of biofuel, on the effectiveness and useful outputs of planned plant are examined. The outcomes of the proposed study show that 18 626, 3948 and 1037 kW electrical energy are generated by using the Brayton, Kalina, and organic Rankine cycle. Furthermore, the total cooling and heating capacities and hydrogen generation rates are 2392, 2864 kW and 0.068 kg s⁻¹. Finally, energetic and exergetic effectiveness of the examined model are calculated as 56.71% and 53.59%.     

Seasonal effects in the nutritional quality of the body structural tissue of cephalopods

The most commonly-consumed cephalopods around the world (the common cuttlefish, Sepia officinalis, European squid, Loligo vulgaris, common octopus, Octopus vulgaris and musky octopus, Eledone moschata) were evaluated in terms of seasonal variations in proximate and fatty acid compositions. The arms of the octopuses were used for this study, whereas the mantle of the other species (squids and cuttlefish) were used for the analyses. The lipid contents of species were found to be very low and considered as lean. The lowest lipid content was obtained from E. moschata (0.60–0.68%), whereas L. vulgaris gave the highest level of lipid (1.34–1.92%) throughout all seasons. Unlike lipid content, protein contents of cephalopods did not change across the seasons. The fatty acid compositions of each species ranged from 28.18% to 35.28% saturated (SFA), 4.36–9.47% monounsaturated (MUFAs) and 43.58–56.55% polyunsaturated acids (PUFAs). The highest proportions of fatty acids in cephalopods were myristic acid (C14:0, 0.96–2.96%), palmitic acid (C16:0, 15.53–25.20%), heptadecanoic acid (C17:0, 1.05–2.56%), stearic acid (C18:0, 4.32–9.96%), oleic acid (cis18:1 n−9, 1.80–4.29%), cis-11-eicosenoic acid (C20:1, 2.07–4.69%), linoleic acid (C18:2 n−6, 0.17–1.95%), arachidonic acid (C20:4 n−6, 1.48–11.65%), cis-5,8,11,14,17-eicosapentaenoic acid (EPA, C20:5 n−3, 7.86–16.97%) and cis-4,7,10,13,16,19-docosahexaenoic acid (DHA, C22:6 n−3, 20.99–39.00%). The results indicated that these cephalopod species are excellent protein sources and very rich in n−3 fatty acids.     

A novel analysis and design of a neural network assisted nonlinear controller for a bioreactor

A novel approach is presented for the analysis and the design of a controller for a bioreactor. It is based on the model reference control theory, assisted by a neural network identifier. The control objectives specified in the paper require the controller to be a nonlinear one, however, it is shown that it is stable in the sense of bounded input bounded output and locally stabilizing in the sense of Lyapunov. The feasibility and the efficacy of the proposed approach are tested on the benchmark problem. Copyright © 1999 John Wiley & Sons, Ltd.     

EGR control of pressure-wave supercharged IC engines

This paper addresses the problem of exhaust gas recirculation occurring when pressure-wave superchargers are used as boosting devices for IC engines.

During hard accelerations, critical situations arise whenever large amounts of exhaust gas are recirculated over the charger from the exhaust to the intake manifolds of the engine. Such recirculations cause the engine torque to drop sharply and thus severely affect the driveability of the vehicle. In order to prevent such situations, the actuators such as throttles, valves, etc., have to be controlled in a coordinated way. Such a control system and its model-based design and verification on an engine test bench are described here in detail.     

Methods of Measuring Bruise Volume of Pear (Pyrus Communis L.)

The grade of injures can be determined or measured by bruise volume using a sectioning and imaging analysis technique and different methods for calculating the size of pear bruises. The calculation methods were not consistent, with large calculation errors at small bruise sizes. The calculation of bruise volume was improved when the surface shape of the bruise was an ellipse instead of a circle. In this study, various methods are recommended for the calculation of the bruise volume depending on the range of the bruise sizes being investigated.     

Effect of Magnesium and Osteoblast Cell Presence on Hydroxyapatite Formation on (Ti,Mg)N Thin Film Coatings

TiN and (Ti,Mg)N thin film coatings were deposited on Ti substrates by an arc-physical vapor deposition technique. The effect of cell presence on hydroxyapatite (HA) formation was investigated using surfaces with four different Mg contents (0, 8.1, 11.31, and 28.49 at.%). Accelerated corrosion above 10 at.% Mg had a negative effect on the performance in terms of both cell proliferation and mineralization. In the absence of cells, Mg-free TiN coatings and low-Mg (8.1 at.%)-doped (Ti,Mg)N surfaces led to an early HA deposition (after 7 days and 14 days, respectively) in cell culture medium (DMEM), but the crystallinity was low. More crystalline HA structures were obtained in the presence of the cells. HA deposits with an ideal Ca/P ratio were obtained at least a week earlier, at day 14, in TiN and low-Mg (8.1 at.%)-doped (Ti,Mg)N compared with that of high-Mg-containing surfaces (>10 at.%). A thicker mineralized matrix was formed on low-Mg (8.1 at.%)-doped (Ti,Mg)N relative to that of the TiN sample. Low-Mg doping (<10 at.%) into TiN coatings resulted in better cell proliferation and thicker mineralized matrix formation, so it could be a promising alternative for hard tissue applications.