Biodiesel Production from Waste Frying Oils by Potassium Methoxide Supported on Activated Carbon Catalysts from Lignocellulosic Biomass

Various carbon-rich solid catalysts are evaluated for the synthesis of biodiesel from waste frying oil. The study results showed that the use of activated carbon made of corn stalk could increase the biodiesel yield by 7%. The heterogeneous carbon-based catalysts made of lignocellulosic residues could successfully improve the quality of biodiesel properties. The results obtained revealed that the biodiesel properties, including relative density (852–900 kg·m−3) and kinematic viscosity (2.4–3.9 mm2·s−1), are in compliance with the standard limits of ASTM and the European Biodiesel Standard, suggesting that the biodiesel produced would be decent as a diesel fuel that potentially can minimize the serious damage of engine parts, and prolong the engine life.

Comparison of Control Algorithms by Simulating Power Consumption of Differential Drive Mobile Robot Motion Control in Vineyard Row

The paper deals with comparing electricity power consumption of various control algorithms by simulating differential mobile robot motion control in a vineyard row. In field of autonomous mobile robotics, the quality of control is a crucial aspect. Besides the precision of control, the energy consumption for motion is becoming an increasingly demanding characteristic of a controller due to the increasing costs of fossil fuels and electricity. A simulation model of a differential drive mobile robot motion in a vineyard row was created, including robot dynamics for evaluating motion consumption, and there were implemented commonly used PID, Fuzzy, and LQ control algorithms, the task of which was to navigate the robot through the centre of vineyard row section by measuring distances from trellises on both robot sides. The comparison was carried out using Matlab software and the best results in terms of both power consumption and control accuracy were achieved by LQI controller. The designed model for navigating the robot through the vineyard row centre and optimized controllers were implemented in a real robot and tested under real conditions.

Performance Evaluation of Solar Air Collector by Chimney Effect for Drying Applications

Solar air collector is one of the main components of a solar dryer unit, which supplies the conditioned air for processing the perishable edible items. Various techniques have been employed to improve the thermal efficiency of the collector system, such as extended surfaces, packed beds, artificial roughness, etc., however, the cost of construction is higher. Therefore, this study was focussed on the collector efficiency enhancement using a chimney without applying the aforementioned. A single-pass solar air collector coupled with drying chamber and chimney was utilized for the experiments. The experiments were conducted in September. The average values of the solar radiation intensity, ambient temperature, temperatures inside the dryer, collector efficiency were graphically presented. The experimental data reported the maximum values of the outlet temperatures for the solar air collector with and without a chimney to be 52.8 °C and 57 °C, respectively. The collector thermal efficiency with and without the chimney was found to vary from 29.6% to 64.8% and from 26.9% to 44.8%, respectively. Furthermore, it was noticed that, with the chimney, the temperature inside the dryer showed uniform tendency.

Mechanical Properties of Wheat Grains at Compression

Hook’s law for evaluation of the modulus of elasticity of wheat grains and its general behaviour under compressive loads were studied. Whole specimens were subjected to compressive loading between metal parallel plates. The mechanical properties of grains were determined in terms of average failure strengths of grain bran and whole grain; deformation; and modulus of elasticity. The mechanical properties of very dry grains of the winter wheat Triticum aestivum L. with the moisture content of 10.3% were studied. The failure strength of grain bran was 4.43 MPa at the deformation of 10.7%, and the failure strength of whole grains was 4.88 MPa at the deformation of 13.5%. The modulus of elasticity of grains was 43.67 MPa. The apparent energy density at bran failure strength was 0.261 MJ·m−3, and 0.470 MJ·m−3 on the level of grain failure strength of the whole grain. The bran border structure of central inner part of grains was studied using microscope digital sections of longitudinal cuts of the grains using the image computer processing method. The area proportion of starch and pericarp of the border parts of grains was studied to describe the border texture of central sections of grains.

Spruce and Barley Elemental and Stochiometric Analysis Affected by the Impact of Pellet Production and Torrefaction

Biomass is a potential biofuel which may help fighting high carbon dioxide emissions and negative impacts of global warming. Analysis of Norway spruce (Picea abies) and barley (Hordeum vulgare) were performed at the laboratory of Czech University of Life Sciences. Material was torrefied in an inert nitrogen atmosphere at the temperatures of 250 °C and 280 °C for 45 minutes. Elementary and stoichiometric parameters were monitored and impact of torrefaction and pellet production on carbon footprint was determined. Torrefied and pelleted material showed better fuel properties in comparison to the original material. Calorific value of the torrefied spruce wood chip increased by 12.27% when torrefied at the temperature of 250 °C, and by 25.41% when torrefied at the temperature of 280 °C.

The Control Reversing Algorithm for Autonomous Vehicles with PSD-Controlled Trailers

Driving a vehicle with a passive trailer has been the subject of numerous studies. Current control strategies are mostly used by differential geometry, linear algebra, fuzzy regulators, and artificial neural networks. The objective of this study is to design an algorithm for autonomous control of the tractor-trailer system reversing based on an algorithm using a PSD controller and to verify it on a simulated mathematical model. All parameters listed in the models and experiments are performed based on the existing tractor-trailer system. Dynamic models of steering and velocity control were identified and incorporated into the simulation. Result includes a stable operation of the steering without oscillating. The proposed algorithm can be implemented in microcontrollers without the need for high computing power.

The Effect of Crop Residue Percentages and Their Chopped Size on Soil Compactibility

The advancement of technology and increasing use of mechanization in agriculture, as well as increasing size of agricultural machinery for farm capacity improvement, have led to soil compaction. In developed countries, various reports of the soil compaction impacts on the reduction of agricultural products have been provided. In developing countries, soil compaction represents a less-known issue and a its destructive nature in agriculture has not been sufficiently addressed. Furthermore, in developed countries, the soil is rich in organic matter due to conservation tillage; however, in Iran, conservation tillage is not possible to perform because of traditional agriculture and using old agricultural machinery. Therefore, plant residues are either removed from fields, or burned. However, sufficient content of organic matter in field can contribute to soil compaction mitigation. The aim of this study was to investigate the effect of percentage of crop residues and their size on soil compaction at different soil moisture contents. For these purposes, five different soil moisture contents (8, 10, 12, 14 and 16% based on dry soil weight) and 4 residue rates at 3 fragmentation sizes were observed in terms of soil compaction. At all different soil moisture contents and residue sizes, with increasing percentage of added straw to the soil, the soil displacement increased. Moreover, as the straw size increased, the initial displacement during compression decreased, e.g., the maximum displacements for straw percentage of 12% and soil moisture of 8% were 64, 62 and 60 mm considering the straw sizes of 1, 2.5 and 5 cm, respectively. With high residue percentage, the final soil density and soil compaction were lower due to the low specific density of straw relative to soil. Furthermore, with high percentage of straw, more deformations and displacements were occurred in the mixture due to large deformation of straws. The density changes of soil-straw mixture were more significant at high residue percentages.

Assessment of the Possibility of Reducing the Thermal Load in the Barn by using Mechanical Ventilation

The aim of this work is to evaluate possibility of reducing the heat stress of milking cows via climatic indices and the influence of air flow velocity in the object with milking cows using the cross-section method. For the purposes of evaluation, there was selected a four-row housing facility for 160 milking cows with natural ventilation; for the summer period, natural ventilation was supplemented with mechanical ventilation (2877 m3·h−1 per cow). Measurements were conducted in the network created with 12 measuring points across the barn width, repeated in five cross-sections A, B, C, D and E, followed by further measurements in the longitudinal direction performed always in a row of 22 points placed in resting zones along the air flow direction. Considering the state of potentially high heat load with THI >78, it was observed that, according to ETIC, without employing the fans, ETIC in AOZ was higher than nAOZ, ETICAOZ = 25.34 ±0.42 vs ETICnOAZ = 24.51 ±0.44 (p <0.05). After activation of fans above lying area, ETIC in AOZ was lower than nAOZ, ETICAOZ = 23.40 ±0.61 vs ETICnAOZ = 23.68 ±0.60, which was not validated in evaluation of THI. Even though the limiting value of very high heat stress ETIC = 25 was not exceeded after activation of fans, decreasing of heat stress in rest zones did not reach recommended value ETIC = 20. A more significant improvement was validated in ETIC evaluation with measurements in longitudinal direction in the lying area – there was confirmed dominant influence of air flow speed. Heat load decreasing was influenced by speed and distribution of air in AOZ, both overall and local air exchanges in AOZ with ACHv >100 h−1, and barn length.

Water Consumption in the Automatic Milking Systems

The article deals with the determination of water consumption at selected dairy farms during milking using automatic milking systems (AMS). The aim was to determine the water consumption during basic activities associated with the AMS use, namely water for cleaning the milking set and water for cleaning and disinfecting the entire milking system at set daily intervals (hereinafter water). The research was carried out at seven farms in the Czech Republic, which house dairy cows of the black-spotted Holstein cattle. The evaluated groups of dairy cows had from 97 to 103 milked cows for the entire monitored period. Based on the performed measurements, it was found that the average amount of water consumed by AMS per 1 litre of milked milk was 0.33 litres. The results show that water consumption is not completely constant during the year. Multiple factors, including performance, the number of non-drinking milk detections, animal health and current climatic conditions, influence it.

Development and Evaluation of Personal Urban Concept Vehicle Powered by a Hydrogen Fuel Cell

To reduce the levels of harmful emissions and to minimize the noise pollution, many leading countries have started pilot projects and initiatives for gradual transition to electrical vehicles or vehicles powered by alternative fuel sources, including natural gas, hydrogen, propane, biofuels, and methanol. Parallel to this, many automotive companies are also exploring and using every possibility to introduce newer manufacturing technologies and materials in the vehicle development and construction processes. The results of these efforts are vehicles that are lighter and have lower fuel consumption, but at the same time are capable to provide the industry approved levels of comfort, reliability, and protection to the passengers. One of the many drivers for the abovementioned evolution of the automotive industry are the numerous events and races, where teams from different countries and continents are competing for dominance. The focus of this paper is to present the processes for design, development and evaluation of a hydrogen fuel cell powered racing vehicle, which was developed at the “Angel Kanchev” University of Ruse in Bulgaria. The paper presents results from simulated and real on-track experiments with the vehicle prototype. Emulations and analysis on the possibilities to improve the vehicle performance, as well as to increase the effectiveness of the vehicle power supply system, using a system for regenerative braking, are also provided in the last section of the paper.