New correlations for heat transfer coefficients during direct cooling of products

An analytical method for determining the heat transfer coefficients of food products being cooled in water and in air flows is presented. Food products are idealized as geometrical solid objects of regular shapes. New correlations between heat transfer coefficients and cooling coefficients are developed in simple forms for practical use in the refrigeration industry. These correlations are then used to determine the heat transfer coefficient for a cylindrical carrot cooled in air flow as an illustrative example. In addition, evaluating the heat transfer coefficients for several products using the available experimental cooling coefficient values from the literature, two new correlations between the heat transfer coefficient and the cooling coefficient are also obtained for water and air cooling applications. The results show that the correlations presented in this article can determine the heat transfer coefficients of food products forced-convection cooling in a simple and accurate manner.     

Effects of Kosovo’s energy use scenarios and associated gas emissions on its climate change and sustainable development

Climate change will be the first truly global challenge for sustainability. Energy production and consumption from fossil fuels has central role in respect to climate change, but also to sustainability in general. Because climate change is regionally driven with global consequences and is a result of economic imperatives and social values, it requires a redefinition as to the balance of these outcomes globally and regionally in Kosovo. Kosovo as one of the richest countries with lignite in Europe, with 95–97% of the electric power production from lignite and with 90% of vehicles over 10 years old, represents one of the regions with the greatest ratio of CO₂ emissions per unit of GDP, as well as one of the countries with the most polluted atmosphere in Europe. The modelling is carried out regionally for Kosovo for two dynamical systems which are the main emitters of greenhouse gases (CO₂, CH₄, NO_x, etc.) and air pollutants (CO, SO₂, dust CH_x, etc.): electricity generation and transportation emissions systems, for the time period 2000–2025. Various energy scenarios of the future are shown. We demonstrate that a transition to environmentally compatible sustainable energy use in Kosovo is possible. Implementing the emission reduction policies and introducing new technologies in electrical power production and transportation in Kosovo ensure a sustainable future development in Kosovo, electric power production and transport that become increasingly environmentally compatible.     

Laparoscopic-assisted vaginal hysterectomy and bilateral salpingo-oophorectomy with suturing technique

Since December 1992 we have performed laparoscopic-assisted vaginal hysterectomy (LAVH) in 50 women using strict, conventional, basic operative rules, and compared it with open abdominal hysterectomy with respect to operation time, cost, postoperative analgesia requirements, and length of hospital stay. The indications for hysterectomy were uterine myoma in 32 patients, dysfunctional bleeding in 13, and postmenopausal bleeding in 5. The mean operating time was 118 minutes. The mean blood loss was 3.2% for preoperative and postoperative hematocrit values. The complication rate was 15%. The advantages of LAVH include short hospitalization, early recovery, low blood loss, and minimal postoperative discomfort.     

Type-2 fuzzy neural networks with fuzzy clustering and differential evolution optimization

In many real-world problems involving pattern recognition, system identification and modeling, control, decision making, and forecasting of time-series, available data are quite often of uncertain nature. An interesting alternative is to employ type-2 fuzzy sets, which augment fuzzy models with expressive power to develop models, which efficiently capture the factor of uncertainty. The three-dimensional membership functions of type-2 fuzzy sets offer additional degrees of freedom that make it possible to directly and more effectively account for model’s uncertainties. Type-2 fuzzy logic systems developed with the aid of evolutionary optimization forms a useful modeling tool subsequently resulting in a collection of efficient “If-Then” rules.The type-2 fuzzy neural networks take advantage of capabilities of fuzzy clustering by generating type-2 fuzzy rule base, resulting in a small number of rules and then optimizing membership functions of type-2 fuzzy sets present in the antecedent and consequent parts of the rules. The clustering itself is realized with the aid of differential evolution.Several examples, including a benchmark problem of identification of nonlinear system, are considered. The reported comparative analysis of experimental results is used to quantify the performance of the developed networks.     

Synthesis and properties of KTN films by sol-gel deposition and RF-magnetron sputtering

Homogeneous KTN (Potassium Tantalate Niobate) solutions were prepared using potassium acetate and metal alkoxides in 2-methoxyethanol by controlled hydrolysis with 1:2 (KTN/H₂O) molar ratio. We report on the synthesis of sol-gel KTN for both the fabrication of homogeneous, dense and stoichiometrically correct ceramic discs by hot isostatic pressing and the deposition of spin-on as well as sputtered thin films. The spin-on KTN films on Pt/Si or r-sapphire were polycrystalline and stoichiometric, however, sputtered films on sapphire were fully (100) oriented and polycrystalline on Pt/SiO₂/Si substrates with some potassium deficiency. The refractive indices of sputtered, dense KTN films on sapphire were between 2.00 and 2.05.     

Investigation of tribological and mechanical properties of metal bearings

Copper, aluminum and tin-lead based alloys are widely used as journal bearing materials in tribological applications. Bronze and brass are widely used as journal bearing materials for copper based alloys. Zamacs find applications as journal bearing materials for zinc based alloys, while duralumines are chosen as journal bearing materials for aluminum based alloys. In addition, white metals are widely used as journal bearing materials for tin-lead based alloys. These alloys ensure properties expected from journal bearings. In this study, tribological and mechanical properties of these journal bearings manufactured by metals were investigated. SAE 1050 steel shaft was used as counter abrader. Experiments were carried out in every 30 min for a total of 150 min by using radial journal bearing wear test rig.     

Electrical transport and structural study of CuCr1 − xMgxO2 delafossite thin films grown by pulsed laser deposition

The growth and properties of delafossites CuCr_1 − xMg_xO₂ thin films are examined. These films are grown by pulsed laser deposition. As a class of materials delafossites have received recent interest since some members show p-type behavior. While not considered true wide-bandgap materials due to a narrow indirect bandgap that fails to adsorb light due to a forbidden same parity transition, optical transparencies greater than 40% in the visible can be observed. In order to be useful for transparent device applications, CuCr_1 − xMg_xO₂ films are needed with low resistivity and high optical transparency. Epitaxial films of CuCr_1 − xMg_xO₂ were grown on c-sapphire, examining the effects of oxygen pressure and growth temperature on film properties. Films were realized with resistivity of ~ 0.02 Ω-cm and optical transparency of 40% in the visible. The formation of a problematic secondary minority spinel phase of (Cu,Mg)Cr₂O₄ is discussed. While conductivity increases substantially with Mg doping, the incidence of the spinel phase increases as well.     

Coupled Mechanical and Hydraulic Modeling of Geosynthetic-Reinforced Column-Supported Embankments

Geosynthetic-reinforced column-supported (GRCS) embankments have increasingly been used in the recent years for accelerated construction. Numerical analyses have been conducted to improve understanding and knowledge of this complicated embankment system. However, most studies so far have been focused on its short-term or long-term behavior by assuming an undrained or drained condition, which does not consider water flow in saturated soft soil (i.e., consolidation). As a result, very limited attention has been paid to a settlement-time relationship especially postconstruction settlement, which is critical to performance of pavements on embankments or connection between approach embankments and bridge abutments. To investigate the time-dependent behavior, coupled two-dimensional mechanical and hydraulic numerical modeling was conducted in this study to analyze a well-instrumented geotextile-reinforced deep mixed column-supported embankment in Hertsby, Finland. In the mechanical modeling, soils and DM columns were modeled as elastic-plastic materials and a geotextile layer was modeled using cable elements. In the hydraulic modeling, water flow was modeled to simulate generation and dissipation of excess pore water pressures during and after the construction of the embankment. The numerical results with or without modeling water flow were compared with the field data. In addition, parametric studies were conducted to further examine the effects of geosynthetic stiffness, column modulus, and average staged construction rate on the postconstruction settlement and the tension in the geosynthetic reinforcement.