Performing biofuel use studies, a large number of parameters that characterize engine operation under different conditions and with different fuel mixtures have to be identified. The real driving conditions are usually simulated by driving cycles on a laboratory chassis dynamometer. There are two major categories of driving cycles: legislative and non-legislative. From the viewpoint of cycle formation there are also two ways. One is composed of various driving modes of constant acceleration, deceleration and speed, and is referred to as modal or polygonal. The other type is derived from actual driving data and is called as 'real world' cycle. There is a strong agreement among researchers that driving characteristics of each city are unique because of different vehicle fleet composition, driving behaviour and road network topography. It is therefore better to develop own driving cycles than using driving cycles developed elsewhere. The aim of this investigation is to develop driving cycles or models for dynamometer control software corresponding to peculiarities of Latvia. The procedure for cycle development and fuel consumption and exhaust emissions measurement was worked out. Using real driving data on the Jelgava streets, models simulating driving in different urban areas were constructed. The model quality was determined using vehicle driving parameters and fuel consumption measurement results from both the road and laboratory tests. Since the obtained data coincidence of all the parameters exceeded 98%, the elaborated cycles can be used for the biofuel use efficiency determination.

Rising oil prices, national security concerns, the desire to increase farm incomes, and a host of new and improved technologies are propelling the European Union to set the directive for the year 2010 – each member state should achieve at least 5.75% biofuel usage of all used transport fuel. The report on the progress made in the use of renewable fuels shows that the average Member State of the EU has achieved only 52% of its target, and biofuels’ share in 2010 will not raise much above 4%. The prices of different biofuels are still not able to compete with oil based fuel prices. One of the possible ways how to solve this problem is to optimize biofuel supply chains using different methods of systems engineering. The aims of this investigation were finding out appropriate simulation tools for biofuel supply chain modelling, development of rapeseed oil supply chains for different production types, and modelling the developed supply chains. As the result of software survey, two packages were chosen – AnyLogic and ExtendSim Suite. Modelling studies showed that rapeseed oil supply chain is very sensitive, because changing just single parameters in a short scale, the actual cost price of 1 litre of oil changes considerably. Comparing the fossil diesel fuel prices with rape oil actual cost from modelling studies, the use of oil as a fuel for farm machinery seems to be profitable. Analysis of costs distribution shows that the greatest part is composed by rapeseed growing expenses.

Today e-learning is a term which is commonly used, but does not have a universally accepted definition, but it can be considered as technology-enhanced learning, where all types of digital technologies are used to support the learning process. Over the years some new functionality has appeared as mobile and wireless technologies (m-learning) and digital television provided possibilities for interactive study materials management (tv-learning). Latest options for training process acceleration are offered by virtual and augmented reality (VR/AR) technologies. The aim of this paper is to find solution for appropriate hardware selection before constructing VR/AR system for training needs focusing on platforms used for operators preparation to work with industrial equipment. In the beginning of the paper all hardware devices for such systems are summarized and explained. Then by using set theory and combinatorics all possible sets of input/output devices are described and calculated. Next dynamic modelling is used to create deterministic, static simulation model with an aim to ease the process of hardware selection for VR/AR training systems development. Simulation model is used for development of two pilot projects.

The research paper discusses simulation of the loading process of the vertical axis wind turbine with the permanent magnet synchronous generator. Experimental and analytical studies were done in the year 2013. The research results show that electrical load on the wind turbine generator is important for the wind turbine performance. If the load is above or below the power gained from the wind energy, the turbine operation cannot be considered efficient and its dynamic parameters fail to achieve the efficiency level at the proper operation load when the load is built up strictly in accordance with the wind energy input. In the research, 3 separate virtual electrical loading models with static, discrete, dynamic electrical load were established. MATLAB SIMULINK simulated virtual model shows the importance of usage of the right amount of electrical load in the vertical axis wind turbine with the permanent magnet synchronous generator. Final research results showed that the most effective loading process of wind turbine generator is a dynamic load.

Birch plywood has proved itself to be one of the most rational ways of wood processing. Growing demand of high performance birch plywood products requires a complex numerical analysis based on Finite Element Method (FEM), instead of using simple analytical assumptions, which prevent optimization of plywood construction (lay-up). In the research samples of birch plywood of several thicknesses, both sanded and non-sanded, with fibre direction of external veneer both in the longitudinal and transverse directions were tested. An extensometer and optical strain gauge were used for strain measurement. The FEM analysis, using commercial software SolidWorks Simulation Premium (SW), versus experimental bending and tension testing according to LVS EN 789 was carried out in this paper. The analysis of results indicates that there is a high correlation between the results of the experiments and the FEM. Particularly for in tension loaded specimens one can be tested up to the maximum ply strength (100 MPa); meanwhile, in bending up to 71MPa – the average stress in load bearing ply at the proportionality limit. Due to software restrictions, shear stresses cannot be evaluated. Future studies are considered to investigate terms for designing plywood with dynamic properties of strength and stiffness to be taken into account.

The task of this paper is to create a simulation model of wood resource flow, enabling analysis of the flow of resources to the customer. The model consists of four modelling steps - the study of the system, the creation of conceptual and logical model, as well as data analysis. The model has been developed in UML (Unified Modelling Language) diagrams and the simulation model has been created using software EXTEND Industry. For the simulation of the model the scenario has been created. Based on this scenario, extended scenarios have been developed. Model of basic simulation represents the loading of resources into the transport, transportation, discharging from the transport and the return to the loading point. Using this basic scenario, the extended scenario has been created. This scenario analyzes the flow of wood resources to the customer, taking into account two criterions restricting the flows - assortment to be processed and the distance from the loading place to the customer's location. Extended scenario allows to analyze the load of each sector, as well as to follow each unit existent in the process of simulation. There are attributes of information (type, assortment etc.) added to the unit equivalent to 1m**3 of wood resources. These attributes can provide information about the unit flow within any part of the process.

One of the prior trends of research is the problem studies of power economy of technological processes and quality automatic control. Though the theory of grain drying process has been developed profoundly, still there are problems in its implementation. The developed analytical and simulation models of grain drying are difficult to implement into practice because they do not contain all the factors, which influence the real grain drying process or they cannot be solved. The developed models enable to assess only the essentiality of factors and/or the fundamental basics of the process. In order to ensure the effective and user-friendly grain drying process, it is indispensable to develop the control methodology using system modelling approach. The present paper deals with the system approach to heat and mass transfer problem and the testing of the basic hypothesis of the diffusion theory about the normal distribution of particles in the diffusive environment.

In conditions where induction motors are frequently started, overloaded and used in high inertia applications with long starting times, supplied from frequency converter, a temperature protection system are more reliable to protect induction motor stator winding against thermal overloads. There are different types of temperature protections - thermostat, PTC thermistor, resistance temperature detector (RTD) and thermocouples, so it is important to know the properties of each type to choose an adequate protection system. Analyses of temperature sensor properties and their advantages and disadvantages show, that PTC thermistor is a cost-effective temperature protection solution, but for medium and high voltage induction motor protection RTD are commonly used. A virtual model has been represented to simulate the temperature sensor thermal time constant under different thermal conductivity and thickness of winding magnet wire insulation.

The purpose of this study was to predict and compare salt accumulation in the soil profile under drained and undrained conditions. The water management simulation model, Drainmod (Ver. 6.1) was used to determine the optimal drainage system design parameters, which will decrease soil profile salinity and provide maximum crop yields in Ankara-Bala Basin of Turkey. Soil sampling points were coordinated with the Global Positioning System (GPS). Soil, crop and site parameters were obtained as an input. The model was run for 5 years from 2005 to 2010 to simulate optimum drainage design parameters (drain depth, drain spacing) while controlling soil salinity in the root zone. Soil water conditions and soil salinity level were simulated for crop rotation of corn (Zea mays) and winter wheat (Triticum). Yield of individual crops was predicted for each growing season. The results of the simulations were analyzed to identify alternatives of subsurface drainage system that would satisfy maximum crop productions. According to the simulation results, the drain spacing of 130 m and drain depth at 160 cm are recommended for Bala Basin. Soil salinity maps were created for undrained and drained conditions. Results showed that the soil salinity level and salinity stress can be reduced and yield increased by installing a drainage system.