International Journal of Geology

E-ISSN: 1998-4499
Volume 15, 2021

Notice: As of 2014 and for the forthcoming years, the publication frequency/periodicity of NAUN Journals is adapted to the 'continuously updated' model. What this means is that instead of being separated into issues, new papers will be added on a continuous basis, allowing a more regular flow and shorter publication times. The papers will appear in reverse order, therefore the most recent one will be on top.

Main Page

Submit a paper | Submission terms | Paper format


Volume 15, 2021

Title of the Paper:  Influence of the Heat Loss on the Performance of a Two-stage Gasification Reactor


Authors:  Martino Paolucci, Carlo Borgianni, Sonia Panzieri, Benedetta de Caprariis, Paolo De Filippis

Pages: 61-63

DOI: 10.46300/9105.2021.15.9     XML

Abstract: This paper investigates the gasification efficiency of a two stage gasifier, described in all detail in previous works, as a function of the heat loss across the reactor walls. The behaviour of the reactor was simulated using a simple mathematical model already reported in previous papers. The examined heat loss ranges from 0% of the heat produced by the exothermic reactions into the reactor, up to 20%. Calculations have been performed by keeping constant both the injected total oxygen and its partition between the two stages, while different feedstocks have been used, such as landfill gas, municipal solid waste (MWS), willow and rice straw. The results of calculation show that the gasification efficiency at fixed oxygen injection is greatly influenced by the feedstock. The elaboration of the obtained data indicates also that the trend of the gasification efficiency vs. heat loss is a function of the high heating value of the feedstock and of the ratio between the oxygen present into the reactor (injected + the one of the feedstock) and the stoichiometric oxygen necessary to transform the feeding into carbon dioxide and steam.

Title of the Paper:  Wind Energy Versus Natural Gas in Latvia: Policy Evaluation With a System Dynamic Simulation


Authors:  A. Skujevska, F. Romagnoli, T. Zoss, I. Laicane, D. Blumberga

Pages: 53-60

DOI: 10.46300/9105.2021.15.8     XML

Abstract: To achieve national target proposed by the Renewable Energy Source Directive 2009/28/EC, to also accomplish to the CO2 emission reduction targets and to decrease the energy dependency Latvian government is planning to adopt different strategy policies such as feed-in tariffs (FITs) and capital subsidies, in order to incentive investor to use renewable based technology for power production Neverthelss it is crucial to understand in long term perspective the effect and the costs of a specific policy (made even by the combination of different policy tools) applied to the energy sector. Using this model, or an extended version of it, a cost/benefit analysis of a different set of policy scenarios can be carried out. More in specific this study is driving its attention at a situation where it is possible to increase the share of wind power in the energy balance respect the use of natural gas as primary energy for power generation. Four political instruments are chosen in this model: subsidies for construction of new wind-power facilities, information package at all power supply levels for risk reduction and reduction of maintenance costs through a learning effect. The simulation period is from 2010 to 2110. The analysis of policy instruments for development of renewable energy resources in power system illustrates wide potential of system dynamic modelling use for statement of priorities on power diversification. The policy instrument of use of subsidies is a crucial priority. Feed-in tariff is not providing an evident. The reason of that can be related to the key aspect on the way Latvia is organizing its feed-in tariff policy.

Title of the Paper:  The Effect of Pyrolysis Temperature on Copyrolysis of Lignite and Pistachio Seed in a Fixed-bed Reactor


Authors:  Özlem Onay

Pages: 49-52

DOI: 10.46300/9105.2021.15.7     XML

Abstract: Co-pyrolysis of lignite and pistachio seed (CPLPS) under nitrogen gas was performed in a Heinze retort. The effect of pyrolysis temperature on product distribution of CPLPS investigated under heating rate of 10°Cmin-1 and blending ratio of 50(wt)%. Biomass is higher yield to be pyrolyzed than lignite and addition of biomass promotes the pyrolysis of lignite. In the range of the experimental conditions investigated the yield of the product is proportional to pyrolysis temperature. On the other hand, considerable synergetic effects were observed during the co-pyrolysis in a fixed bed reactor leading to increase in oil yield. Maximum pyrolysis oil yield of 27.2% was obtained at pyrolysis temperature of 550°C. The obtained oils are characterized by GC, and elemental analysis.

Title of the Paper:  Development of Organic Agriculture: Case of Latvia


Authors:  Tatjana Tambovceva, Andrejs Tambovcevs

Pages: 41-48

DOI: 10.46300/9105.2021.15.6     XML

Abstract: Agriculture is one of the main sectors which many believe should be sustainable, that is, ecologically sound, economically viable, and socially responsible. While conventional agriculture is driven almost solely by productivity and profit, sustainable agriculture integrates biological, chemical, physical, ecological, economic and social sciences in a comprehensive way to develop new farming practices that are safe and do not degrade our environment. Sustainability in rural production system can only be achieved if it can suitably satisfy the local requirement as well as the outside demand with the changing time. This paper reviews the concepts of organic agriculture and examines its development in Latvia.

Title of the Paper:  Anaerobic Degradation of Dairy Wastewater in Intermittent UASB Reactors: Influence of Effluent Recirculation


Authors: A. Silva, I. Capela, L. Arroja, H. Nadais

Pages: 35-40

DOI: 10.46300/9105.2021.15.5     XML

Abstract: This work studied the influence of effluent recirculation upon the kinetics of anaerobic degradation of dairy wastewater in intermittent UASB (Upflow Anaerobic Sludge Bed) reactors. Several laboratory-scale tests were performed with different organic loads in a UASB reactor inoculated with flocculent sludge from an industrial wastewater treatment plant. The data obtained were used for determination of specific substrate removal rates and specific methane production rates and adjusted to kinetic models. A high initial substrate removal was observed in all tests due to adsorption of organic matter onto the anaerobic biomass which was not accompanied by biological substrate degradation as measured by methane production. Initial methane production was about 45% of initial soluble and colloidal substrate removal rate. This discrepancy was observed mainly in the first day of all experiments and was attenuated in the second day. Effluent recirculation raised significantly the rate of removal of soluble and colloidal substrate and methane productivity as compared to literature results for batch assays without recirculation.

Title of the Paper:  Economic Analysis of a Pumped Storage Project for Iran Generating System Based on a Dynamic Modeling


Authors: A.R. Sohrabi

Pages: 30-34

DOI: 10.46300/9105.2021.15.4     XML

Abstract: This paper proposes a dynamic model for evaluation of a Pumped Storage Project (PSP) . The optimal expansion policy is determined by considering different alternatives (Types of units: Rodbar PSP(RPSP), Steam Turbine , 2 types of Gas Turbine and a Combined Cycle) . Based on this model dynamic assessment of different alternatives (over a 20 years period and with a target Loss Of Load Probability (LOLP)) provides economic justification for RPSP.

Title of the Paper:  Nonlinear Friction and Resistance, Generating Sources of Optimal Points in the Energy Field of Agricultural Aggregates Working Process


Authors: Petru Cârdei, Alexandros Alexiou, Mircea Bădescu, Valentin VladuŃ, Nicolae Constantin, Eugen Marin

Pages: 25-29

DOI: 10.46300/9105.2021.15.3     XML

Abstract: The paper presents a point of view on the main sources that can generate some optimal points in the energy field of the agricultural machines working processes. It looks like a possible source of the existence of optimal points in the energetic field of work processes of agricultural machinery and equipment, are the coefficients of friction and specific resistance to deformation of soil. In the news models these coefficients became nonlinear functions. Similar forms are given for all three coefficients and is shown the existence of optimal points. They make some considerations about this method and include results obtained using it.

Title of the Paper: An Approach to the Quality of Drinking Water as a Matter of Multicriterial Decision


Authors: Amelia Bucur, Jose L.Lopez-Bonilla

Pages: 17-24

DOI: 10.46300/9105.2021.15.2     XML

Abstract: The aim of the present paper is to approach the matter of water quality by resorting to the metod of multicriterial mathematical programming. MicrosoftExcel enables the simulation of a mathematical model. Furthermore, we have also created a file in the C++ software, in view of the simulation process, applicable to numberless properties of water quality. The case study presents the simulation of a multicriterial analysis of water quality in Sibiu county. This particular study shows the means of obtaining more information about water quality, subsequent to the analysis of its characteristics resorting to statistical analysis-specific software, e.g. SPSS 16 software. Given the increase of drinking water worldwide by tens of percentage points in cca two decades, the author(s) consider(s) that an approach to the quality management of drinking water should represent a key priority of society.

Title of the Paper: Multi-objective Optimization of SKD11 Steel Milling Process by Reference Ideal Method


Authors: Do Duc Trung

Pages: 1-16

DOI: 10.46300/9105.2021.15.1     XML

Abstract: For all machining cutting methods, surface roughness is a parameter that greatly affects the working ability and life of machine elements. Cutting force is a parameter that not only affects the quality of the machining surface but also affects the durability of cutter and the level of energy consumed during machining. Besides, material removal rate (MRR) is a parameter that reflects machining productivity. Workpiece surface machining with small surface roughness, small cutting force and large MRR is desirable of most machining methods. This article presents a study of multi-objective optimization of milling process using a face milling cutter. The experimental material used in this study is SKD11 steel. Taguchi method has been applied to design an orthogonal experimental matrix with 27 experiments (L27). In which, five parameters have been selected as the input parameters of the experimental process including insert material, tool nose radius, cutting speed, feed rate and cutting depth. Reference Ideal Method (RIM) is applied to determine the value of input parameters to ensure minimum surface roughness, minimum cutting force and maximum MRR. Influence of the input parameters on output parameters is also discussed in this study.