Avoidable and unavoidable exergy destruction and exergoeconomic evaluation of the thermal processes in a real industrial plant

Exergy analysis is a universal method for evaluating the rational use of energy. It can be applied to any kind of energy conversion system or chemical process. An exergy analysis identifies the location, the magnitude and the causes of thermodynamic inefficiencies and enhances understanding of the energy conversion processes in complex systems. Conventional exergy analyses pinpoint components and processes with high irreversibility. To overcome the limitations of the conventional analyses and to increase our knowledge about a plant, advanced exergy-based analyses are developed. These analyses provide additional information about component interactions and reveal the real potential for improvement of each component constituting a system, as well as of the overall system. In this paper, a real industrial plant is analyzed using both conventional and advanced exergy analyses, and exergoeconomic evaluation. Some of the exergy destruction in the plant components is unavoidable and constrained by technological, physical and economic limitations. Calculations related to the total avoidable exergy destruction caused by each component of the plant supplement the outcome of the conventional exergy analysis. Based on the all-reaching analysis, by improving the boiler operation (elimination of approximately 1 MW of avoidable exergy destruction in the steam boiler) the greatest improvement in the efficiency of the overall system can be achieved

Fractal Simulator and Ceramics Technology for New Tesla’s Fountain

In this study, we present new Tesla’s Fountain model in ceramics technology. It is reconstructed from basic 3D model. The model is designed based on Tesla’s original US patent no. 1,113,716, granted on October, 13 (1914). The complete model includes the engine (rotating water pump), colored lights and fluids. This part of the paper is based on research within the project entitled “Computer Simulation and Modeling of the Original Patents of Nikola Tesla” and approved by the Ministry of Education, Science and Technological Development of the Republic of Serbia. The first Tesla's patent that was under our attention in this project was Tesla’s Fountain that is presented in this paper. It is well known that first Tesla’s experiments on Fountain have been realized in materials like bronze-metal. Nevertheless, we used new approach and applied ceramics materials technologies in combination of casting and sintering. We used our original fractal simulator to observe and simulate micro particles movements in Fountain model Finally, we used smoothed-particle hydrodynamics (SPH) as a method of computation and simulating the dynamics of continuum media, like the flow of fluids. The method was developed by Gingold, Monaghan and Lucy in 1977, initially for astrophysical problems. It is also used in astrophysics, ballistics, volcano logy, and oceanography but we find new appliance in our Fountain model. We combine a mesh-free Lagrange method (coordinates move with the fluid) to easily adjust resolution of the simulation with respect to all variables (like the density)

Synthesis and characterization of crosslinked polyurethanes

Two polyurethane samples, crosslinked with aliphatic hyperbranched polyester, were synthesized and examined in this work. The sample PUPDMS-EO was prepared using ethylene oxide-poly(dimethylsiloxane)-ethylene oxide as macrodiol, while the synthesis of PUPTMO was performed using poly(tetramethyleneoxide). The obtained results show that thermal stability of these networks can be improved by introducing the siloxane sequences. However, the sample PUPDMS-EO has at the same time much lower crosslinking density than PUPTMO.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Influence of CAN fertilizer and seed inoculation with NS Nitragin on glycine max plant on pseudogley soil type

Soybean [Glycine max (L.) Merr.] is the most important legume because it is an essential source of dietary protein and oil for animal feed and food production. Good soil with wellplanned program of fertilization is the main factor of soybean production. Soybean yield will be reduced when essential nutrients are deficient. Sufficient soil fertility combined with a well-planned fertilization program is a main component for high soybean production. The aim of this investigation was to estimate the effects of fertilization and seed inoculation on height of soybean plant in humid year. Two factors were tested: 1. CAN fertilization and 2. seed inoculation. Four treatments of CAN fertilization were tested: Control - 0 kg N ha-1; 50 kg N ha-1; 100 kg N ha-1 and 150 kg N ha-1. Two factors of seed inoculation (SI) were tested: Without SI and with SI. Results showed that fertilizers and seed inoculation significantly increased the values of soybean productivity. Cost effective is the application of 50 kg N ha-1 and it is recommended on the basis of this study

Unsupervised Learning of Invariance Transformations

The need for large amounts of training data in modern machine learning is one of the biggest challenges of the field. Compared to the brain, current artificial algorithms are much less capable of learning invariance transformations and employing them to extrapolate knowledge from small sample sets. It has recently been proposed that the brain might encode perceptual invariances as approximate graph symmetries in the network of synaptic connections. Such symmetries may arise naturally through a biologically plausible process of unsupervised Hebbian learning. In the present paper, we illustrate this proposal on numerical examples, showing that invariance transformations can indeed be recovered from the structure of recurrent synaptic connections which form within a layer of feature detector neurons via a simple Hebbian learning rule. In order to numerically recover the invariance transformations from the resulting recurrent network, we develop a general algorithmic framework for finding approximate graph automorphisms. We discuss how this framework can be used to find approximate automorphisms in weighted graphs in general

A locally signed-distance preserving level set method (SDPLS) for moving interfaces

It is well-known that the standard level set advection equation does not preserve the signed distance property, which is a desirable property for the level set function representing a moving interface. Therefore, reinitialization or redistancing methods are frequently applied to restore the signed distance property while keeping the zero-contour fixed. As an alternative approach to these methods, we introduce a novel level set advection equation that intrinsically preserves the norm of the gradient at the interface, i.e. the local signed distance property. Mathematically, this is achieved by introducing a source term that is proportional to the local rate of interfacial area generation. The introduction of the source term turns the problem into a non-linear one. However, we show that by discretizing the source term explicitly in time, it is sufficient to solve a linear equation in each time step. Notably, without adjustment, the method works naturally in the case of a moving contact line. This is a major advantage since redistancing is known to be an issue when contact lines are involved (see, e.g., Della Rocca and Blanquart, 2014). We provide a first implementation of the method in a simple first-order upwind scheme.Comment: 18 pages, 5 figure

Odredjivanje silanolnih krajnjih grupa u polisiloksanima dobijenim iz dimetildihlorsilan hidrolizata (ddsh)

Dimethyldichlorosilane hydrolysate, DDSH, the linear part of which contains SiOH end groups, can be used in the preparation of difunctionally terminated (any end groups other than SiOH) polysiloxanes via equilibration polymerisations. In such a case, the problem arises: as to whether the obtained functionalised polymers also contain silanol end groups. To the best of our knowledge, the only direct and the most precise analytical procedure to clarify this question is the Karl Fischer titration/determination of SiOH groups. This determination was performed on a model system consisting of trimethylsilyl terminated polysiloxanes, and it was shown that the obtained polymers contained no SiOH groups