Gheorghe Voicu

A Review Regarding the Biogas Production Through Anaerobic Digestion of Organic Waste

Globally, the pollution prevention goals transposed in the Kyoto Protocol, require sustainable solutions regarding the management of organic waste from both agricultural, and livestock farms. Biogas production by anaerobic digestion of organic wastes and residues provides a range of socio-economic benefits, but also environmental, thus contributing to monitoring the complex relationship between human health and the environment. The European Union policies regarding renewable energy systems (Europe 2020 Strategy – A strategy for smart, sustainable and inclusive growth and Green Paper „Towards a European strategy for the security of energy supply“), highlights that the production of renewable energy, reducing greenhouse gas emissions and a sustainable waste management, are essential for sustainable development in the future. In this context, this paper will review aspects of biogas production by anaerobic digestion of organic waste, stages of anaerobic digestion process and concepts of biogas plants used in European countries.

Calculus Elements for Mechanical Presses in Oil Industry

Oil products industry produces edible and inedible oils. About 2/3 of total oil products are the edible oils, which are used directly in foods or in the manufacture of margarine, mayonnaise, bakery and pastry products, cooking fats, preserves etc. The remaining 1/3 of the total volume of produced oil are the technical oils, used in the production of various products, such as: de‐ tergents, paint, glycerin, fatty acids, varnish, pharmaceuticals or cosmetics (Banu, 1999).

Grinding Characteristics of Wheat in Industrial Mills

Grinding of cereal seeds is due to the mechanical action of several forces: compression, shearing, crushing, cutting, friction and collision, to which seeds are subjected, depending on the design if the mill used for grinding (roller mill, hammer mill, stones mill or ball mill). By applying these forces, when the mechanical resistance of the particles is exceeded, their division happens in a number of smaller particles of different sizes, geometric shapes, mass‐ es and volumes.

Aspects Regarding the Collection and Removal of Rainfall Water on Landfill Final Cover

This paper presents an analysis of the rainwater flow on the final cover slopes of an urban landfill so as to ensure the drainage of infiltrate water through the drainage layer applied across the geomembrane of cover layer, with a runoff coefficient as low as possible. It is presented a calculation model for the transmissivity of the drainage layer depending on the thickness and on its hydraulic characteristics and also on the topsoil layer applied to the surface, as well as depending on the coating slope length. This calculation is made for both a side with a single slope (tilt) as well as for sides with two slopes. Also it is presented a mathematical model for the hydraulic calculation of surface water drainage ditches drained through the drainage layers, but also through the surface runoff, in order to establish the optimal drainage section.

Real and simulated mechanical tests

This paper presents the results obtained by the authors when applying mechanical test methods that are validated using fatigue testing under simulated regime with finite element analysis. In addition to the mostly mandatory physical tests, the simulated regime testing can validate emerging conclusions. Virtual testing conclusions (computer simulated via Cosmos finite element analysis software), strengthen, complement and increase the accuracy of physical test conclusions. During the investigation of the physical test results, there are cases where the simulated physical test is not always explainable. This paper presents a case study conducted on special constructed screws that are subjected to fatigue and verified using the finite element analysis. It presents the possibility for practical application of simulated tests in order to redesign structures that fail during physical tests.

Nonstandard mathematical model for fatigue failure

Tests performed under simulated regime, use simulating tools with different structures and often have a corresponding physical test to complete certain conclusions in order to explain complex phenomena that are difficult, impossible, or very costly to run physically. Computer simulations are also called virtual tests beside which there are mechanical or small scale analog simulators. Among the virtual tests for mechanical structures there are structural analysis tests that use numerical analysis methods. Sometimes, in order to understand the phenomena that occurs in the material structure, new complex theoretical models were used for explaining the material quality change. One such application is proposed, which incorporates an old author’s model, for the fatigue and quality phenomenon study of the material change.

SYSTEM FOR DYNAMIC MONITORING AND WARNING IN CASE OF ECOLOGICAL RISK FOR SURFACE WATERS

The dynamic monitoring system continuously performs the monitoring of physicochemical quality indicators of water quality in investigated areas. In case of ecological risk due to accidental pollution situations, the system alarms in real time the decision factors for the diminution of the environmental impacts and other negative effects. The distributed networks of the system are composed of floatable structures of Buoys Monitoring (BM) type, autonomous and adaptable to the environmental conditions specific to a continental climate. They are able to work with reduced maintenance in isolated locations. The BM floatable structure incorporates the sensors and the hardware-software system of data acquisition, processing and transmission. So equipped, BM becomes operational instrument in the infrastructure of the networks of surface waters quality monitoring. The BM model developed allows the continuous in situ evaluation of the health status of the monitored surface water with the scope of warning in case of ecological risk.

The biological factor influence on maize seed production.

This work presents the behaviour of two hybrids in seed growing; these hybrids, DKC 3203 (Monsanto) and Clarica 3893 (Pioneer), are simple hybrids and they are part of FAO 300-400 group. The seed batch was placed within Urleasca locality radius, BrAƒila county, on a chernozem type of soil, with physical and chemical characteristics which are favourable to maize plants’ growth and development, area which is characterized through a semi-droughty steppe climate, with a sprinkling system well refurbished. For the hybrids analysed, after harvest, there were determined the productivity elements (number of kernels/cob, cobs’ average weight, the weight of the kernels/cob), the yield and the quality indices, purity and germination; also, there were performed biometrical measurements (the length and diameter of the cob, and corn car’s diameter) and finally, there were determined the productions obtained. The biometrical measurements showed that the cobs of DKC 3203 hybrid have both the length (13.9 cm) and the diameter (4.1 cm) higher than the ones from Clarica hybrid, 13.6 cm respectively 3.2 cm. At Clarica 3893 hybrid, the cobs have a higher number of kernels (310.15), but the weight of the kernels on a cob (81.69 g) is smaller, due to the fact that the kernels are smaller and not equal in size, as compared with DKC 3203 hybrid, which has smaller number of kernels (304.33), but the kernels are larger (107.35 g) and more uniform. At DKC 3203 hybrid, the yield was 5.1% higher than at Clarica 3893 hybrid, this being correlated with a production higher by 205 kg/ha obtained from the same hybrid. It was observed that at the hybrid from Monsanto company, DKC 3203, it was obtained a production of 3840 kg/ha and a profitability ratio of 62.85% as against the hybrid from Pioneer company, Clarica 3983, at which there was obtained a production of 3635 kg/ha and a profitability ratio of 62.82% in the same climatic conditions and with applying the same technological elements, thus resulting that both hybrids are profitable from economic point of view in order to produce seed, due to the fact that crop’s profitability is over 50%.

Establishing the Quality of Fruits at Some Sorts of Tomatoes Cultivated in Braila County

The analysis and determinations had as purpose establishing the quality of fruits at four sorts of tomatoes from crops set up in the field, by seedling. Tomatoes are cultivated for their fruits that have a pleasant taste and a very high food value. Their nutritive value does not consist in relatively modest content of carbohydrates, but especially in mineral substances and vitamins. Out of the vitamins comprised by tomatoes, the most important are: A vitamin (the importance for the eye and for endocrine processes), B complex (B1, B2, B5, B6 – protectors of the nervous system, of the bones’ system, of metabolism), C vitamin (necessary to cardiovascular system, to nervous and endocrine system), E vitamin (vitamin of youth and fertility) and K vitamin (important for the synthesis of certain figurate elements of the blood). The establishing of the quality of fruits was made through determining the physical characteristics (average weight, form – expressed by the form index, specific weight), chemical composition (total dry substance, humidity, soluble dry substance, titrable acidity, ascorbic acid) and the morphological composition of the fruits (pulp, membrane, seeds).

Experimental Analysis Considered the Dynamics of Mobiles Agricultural Aggregates

When working with agricultural mobile aggregate, t he traction force of equipment and the speed of the real movement vary due to actu al terrain irregularities, appearing also vibration of the gears axes and of the tractor chassis. Starting from these considerations, the paper prese nts results of experimental tests to move on agricultural land of a aggregate consists of a U-65 0M tractor and of a trees vineyard attachment RPV- 2, on the push force of the attachment on the gear- shift bar to the tractor, traction force, vibration acceleration in three points on the tractor and tra ctor skidding for three different speeds of travel. It shall, also the testing equipment and how to cat ch the gage for acquisition the necessary data records. Using known relations in the study of the dynamics of the mobile aggregates, was achieved a modelling program of the traction parameters, in Ma thCad program, with which help were determined and set graphic the variations of the push force on the gear-shift bar, the traction force and the vibration acceleration to the steering wheel of the tractor. Based on experimental results obtained, t he calculation program was checked and improved. The results presented in the paper are of interest to specialists in the study of the dynamic agricultural mobile aggregate, and the modelling pr ogram developed can be used to determine the parameters for the traction and for other types of aggregates to the movement on land with other features than used and tested.