Development and evaluation of graphite nanoplate (GNP)‐based phase change material for energy storage applications

In this study, arachidic acid (AA)/graphite nanoplate (GNP) composite material is proposed as a novel phase change material (PCM). In order to examine the influence of GNP loading into the base material (AA), composite PCMs were prepared with three different fractions (0.5, 1.0 and 2.0 in wt%). The thermal, chemical and morphological characteristics of the samples were introduced in terms of differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared, and X‐ray diffraction analyses. Moreover, the thermal conductivity values of samples in the liquid state were measured by means of 3ω method. It was found that, for GNP fractions of 0.5, 1, and 2 wt. %, the thermal conductivity of composite PCMs have been increased by 15, 30 and 43% in comparison to the pure AA. Results also revealed that the GNP loading into the pure AA led to a reduction in the degree of subcooling and a small diminution in the latent heat values. Considering the thermal cycling tests, it was also obtained that the proposed composite PCMs remained stable even at the highest GNP loading. Conduction‐dominated inward solidification process was simulated for one‐dimensional spherical computational domain. For this particular case, it was found that the increments of 15, 30 and 45% in thermal conductivity tend to increase the effectiveness by 3.5, 6.4 and 8.7%, respectively. Copyright © 2015 John Wiley & Sons, Ltd.     

CVD grown graphene as catalyst for acid electrolytes

Chemical Vapor Deposition (CVD) process is utilized to grow and study behavior of porous, continuous-phase 3D graphene structures in acid electrolyte. Graphene layers that are produced by CVD process are tested for oxygen reduction reaction (ORR) activity by Rotating Disc Electrode (RDE) measurements in 0,1 M HClO₄ electrolyte. Raman spectroscopy measurements confirms multi-layer porous structure formation for more than 1 min grow on nickel foam. Multi-layer porous graphene has provided μA level current. When NH₃ is used for nitrogen (N)-doping, magnitude of the reduction current increases, but still low for practical usage of graphene in acid electrolytes as catalyst. N-doping is confirmed with XPS measurements showing all possible types of N-doping phases with 900 °C being better than 1000 °C doping. CVD grown continuous-phase graphene, by itself or N-doped, cannot provide enough electrocatalytic activity to be used in 0,1 M HClO₄ acid electrolyte or polymer electrolyte membrane (PEM) fuel cells for practical applications. Pt layer of 10 nm has been sputtered on to graphene (21.45 μg/cm² Pt loading) and has provided orders of magnitude increase in oxygen reduction current compare to bare graphene layers.     

Passive thermal management of the lithium‐ion battery unit for a solar racing car

In this study, a three‐dimensional numerical model is developed to investigate the thermal and electrical characteristics of 18 650 lithium‐ion battery cells that are used in the solar racing car of Dokuz Eylül University, i.e., SOLARIS. The Newman, Tiedemann, Gu, and Kim (NTGK) battery model of ANSYS Fluent software is implemented to resolve the coupled multiphysics problem. In the analysis, only the discharging period of the battery is considered. Before going through parametric studies under variable weather conditions, time‐wise variations of the cell temperature and the battery voltage are evaluated both experimentally and numerically under two different ambient conditions of 0°C and 25°C. Comparative results revealed that reasonable predictions are achieved with the current battery model, and the difference between the predicted battery surface temperature and experimental data is less than 1°C. Following the model validation, the battery performance is numerically examined by applying the battery model to a real race procedure of SOLARIS. Phase change materials (PCMs) with different amounts and melting temperatures are implemented around the batteries, and transient analyses are conducted under real weather conditions. The current study aims to keep the battery temperature of a solar racing car above a certain limit to prevent the overcooling and maintain higher charging capacity. Implementation of PCM with a melting temperature of 26°C yields 3.15% of capacity increment, and such a performance improvement corresponds to 15.51 Wh of extra energy that can be extracted from an individual battery.     

The effect of cooking methods on mineral and vitamin contents of African catfish

Proximate composition, mineral and vitamin contents (A, E, B₁, B₂, niacin and B₆) were investigated in cooked African catfish. Different cooking treatments were used (baking, grilling, microwaving and frying). The protein and ash contents increased in all cooked fish. The fat content increased only in fried fillets. The moisture content of cooked fish decreased. Mineral levels were affected by cooking methods, except for Cu Although the vitamin A content significantly increased in grilled and fried fish, vitamin E increased in all cooked fish. Vitamin B₁ content of cooked fish significantly decreased. Vitamin B₂ and niacin contents of grilled fish increased significantly. B₆ content of cooked fish significantly decreased but this did not occur for the grilled fish. High levels of vitamin and mineral contents were found in grilled catfish.     

The influence of polymerization time and dopant concentration on the absorption of microwave radiation in conducting polypyrrole coated textiles

Temperature changes in conducting polypyrrole/para-toluene-2-sulphonic acid (PPy/pTSA) coated nylon textiles due to microwave absorption in the 8–9 GHz and 15–16 GHz frequency ranges were obtained by a thermography station during simultaneous irradiation of the samples. The temperature values are compared and related to the amounts of reflection, transmission and absorption obtained with a non-contact free space transmission technique, indicating a relationship between microwave absorption and temperature increase. Non-conductive samples showed no temperature increase upon irradiation irrespective of frequency range. The maximum temperature difference of around 4 °C in the conducting fabrics relative to ambient temperature was observed in samples having 48% absorption and 26.5 ± 4% reflection. Samples polymerized for 60 or 120 min with a dopant concentration of 0.018 mol/l or polymerized for 180 min with a dopant concentration of 0.009 mol/l yielded optimum absorption levels. As the surface resistivity decreased and the reflection levels increased, the temperature increase upon irradiation reduced.     

A robust technique based on invariant moments – ANFIS for recognition of human parasite eggs in microscopic images

In this study, we propose a robust technique based on invariant moments – adaptive network based fuzzy inference system (IM-ANFIS). In this technique, some digital image processing methods such as noise reduction, contrast enhancement, segmentation, and morphological process are used for feature extraction stage of IM-ANFIS approach used in this study. Recently, the pattern recognition principles have come into prominence. The pattern recognition includes operation and design of systems that recognize patterns in data sets. Important application areas of pattern recognition techniques are character recognition, speech analysis, image segmentation, man and machine diagnostics and industrial inspection. The technique presented in this study enables to classify 16 different parasite eggs from their microscopic images. This proposed recognition method includes three stages. In first stage, a preprocessing subsystem is realized for obtaining unique features from the same group of patterns. In second stage, a feature extraction mechanism which is based on the invariant moments is used. In third stage, an adaptive network based fuzzy inference system (ANFIS) classifier is used for recognition process. We conduct computer simulations on MATLAB environment. The overall success rate is almost 95%.     

Object-oriented texture analysis for the unsupervised segmentation of biopsy images for cancer detection

Staining methods routinely used in pathology lead to similar color distributions in the biologically different regions of histopathological images. This causes problems in image segmentation for the quantitative analysis and detection of cancer. To overcome this problem, unlike previous methods that use pixel distributions, we propose a new homogeneity measure based on the distribution of the objects that we define to represent tissue components. Using this measure, we demonstrate a new object-oriented segmentation algorithm. Working with colon biopsy images, we show that this algorithm segments the cancerous and normal regions with 94.89 percent accuracy on the average and significantly improves the segmentation accuracy compared to its pixel-based counterpart.     

A new MILP model proposal in feed formulation and using a hybrid-linear binary PSO (H-LBP) approach for alternative solutions

Large-scale feed factories may have multiple production and storage facilities. Any production facility uses its own available raw materials while performing feed formulation. However, ensuring a reasonable cost is achieved, and the desired quality criteria are met, may require obtaining a certain amount of raw material from other facilities. Selecting a specific amount of raw materials among many raw materials in different facilities requires many combinations to be tried out. Providing solutions, especially when there is a large amount of the raw material, may be costly and take more time. A new mixed-integer linear programming (MILP) model that specifies the type of material and the amount of the material to be selected from external facilities has been proposed in this study. When deterministic methods like MILP are used, only one solution result is obtained. However, when the decision-maker would like to see alternative results, solution constraints can be mitigated and a solution provided within the same or similar time. A new method named hybrid-linear binary PSO (H-LBP) has been proposed in this study for the problems that the decision-maker had limited time for and for which the solution results were required in a shorter time. Continuous particle swarm optimization, which works as a hybrid with linear programming, has been used in this method. The new model proposed in this study was tested on the mixed feeds for sheep, cattle and rabbit species by using both MILP and the proposed H-LBP methods. Raw materials determined by the model were added to the mixture, and the cost in each of the three species was observed to go down. In addition, different alternative solutions at reasonable cost and similar quality were presented to the producer/decision-maker in a shorter time.

     

Recent progress in Co-based metal-organic framework derivatives for advanced batteries

To date,Co-based metal-organic frameworks (Co-MOFs) have drawn much attention owing to their ad-vantages of easy preparation,high porosity and adjustable struct...