Oxidation of chalcopyrite in air-equilibrated acidic solution: Inhibition with phenacyl derivatives

The effects of 4-(2-hydroxyphenyl)-2-(morpholin-4-yl)-1,3-thiazole(Pr02), 1-(3,5-dibromo-2-hydroxyphenyl)-1-oxoethan-2-yl-N,N-diethyldithiocarbamate(Pr04) and 1-(5-bromo-2-hydroxy-3-methylphenyl)-1-oxoethan-2-yl-Oethyl xanthate(Pr06) on the aqueous oxidation of chalcopyrite(CuFeS2) in air-equilibrated solution at a temperature of 25 ℃ and a pH of 2.5 were studied. The effects were investigated by using potentiodynamic polarization, electrochemical impedance spectroscopy(EIS), scanning electron microscopy coupled with energy dispersive X-ray(SEM/EDX) analysis, aqueous batch experiments, Fourier transform infrared(FTIR) spectroscopy, Raman scattering and quantum chemical calculations. It is found that the anodic current densities decrease in the order of EtOH > Pr02 > Pr04 > Pr06. These results, along with those of the EIS measurements, show that Pr02, Pr04 and Pr06 are effective anodic inhibitors of chalcopyrite aqueous oxidation. Both Raman scattering and FTIR spectroscopy indicate that the elemental sulfur, polysulfide and ferric oxyhydroxides that form on the surface of the mineral are not responsible when it comes to the aqueous oxidation inhibition of chalcopyrite. Quantum chemical calculations show that the adsorption of the tested compounds on the chalcopyrite surface is energetically favorable and so, it can explain the inhibiting effects that were observed.

Smart cities from low cost to expensive solutions under an optimal analysis

This scientific approach mainly aims to develop a smart city/smart community concept to objectively evaluate the progress of these organizational forms in relation to other classical/traditional forms of city organizations.The elaborated model allowed the construction of the dashboard of access actions in the smart city/smart community category on two levels of financial effort correlated with the effect on the sustainable development of smart cities.The validity of the proposed model and our approach was supported by the complex statistical analysis performed in this study.The research concluded that low-cost solutions are the most effective in supporting smart urban development.They should be followed by the other category of solutions,which implies more significant financial and managerial efforts as well as a higher rate of welfare growth for urban citizens.The main outcomes of this research include modelling solutions related to smart city development at a low-cost level and identifying the sensitivity elements that maximize the growth function.The implications of this research are to provide viable alternatives based on smart city development opportunities with medium and long-term effects on urban communities,economic sustainability,and translation into urban development rates.This study’s results are useful for all administrations ready for change that want the rapid implementation of the measures with beneficial effects on the community or which,through a strategic vision,aim to connect to the European objectives of sustainable growth and social welfare for citizens.Practically,this study is a tool for defining and implementing smart public policies at the urban level.

Food Behavior Correlated with Lifestyle Pattern and Societal Influences in a Romanian Students Population. Part I: Eating General Habits

Input data from Students Food Behavior, Preference and Lifestyle Questionnaire conducted with 376 students from University “Dunarea de Jos” Galati (UDJG) were analyzed from socio-demographic criteria. The sample socio-demoraphic characteristics of the student population were investigated beside the general food & eating habits by gender. In the current study, most than three quart of students (76.06%) was of correct (normal) weight. Nearly 65.15% of the students reported having regular daily breakfast. The strongest correlation of having breakfast habit is show with the regular meal behaviour [r(3, 4) = 0.242] and regular meals were associated with reduced trends for BMI [r(4, 2) =-0.055].

Marine Current Turbine Simulator Development Based on Hardware in the Loop Simulation Concept

This paper is a contribution to the development of real time simulators for energy conversion research with respects to the ＂hardware in the loop simulation＂ concept. The focus is on the study of marine current kinetics energy conversion from into electrical energy using a marine current turbine simulator, developed in three stages. In the first stage the marine current turbine is emulated with the help of an induction drive who reproduces at its shaft the characteristics of a real turbine. It is connected with a load break used to force the emulator to respect on its shaft the characteristics of the real turbine. In the second stage, the induction drive is connected on the shaft with a doubly feed induction generator, for the study of energy conversion. The emulator respects the working regime, developed in the previous step, of a real turbine due to the control of the drive. In the third stage the induction machine emulating the turbine is interconnected with the generator and the load break. This assembly is used for the dynamic study of the marine current turbine. The break is used to create extra loads on the shaft and a variable inertial moment.

Wear behavior of Ti6Al4V biomedical alloys processed by selective laser melting, hot pressing and conventional casting

The aim of this work was to study the influence of the processing route on the microstructural constituents,hardness andtribological(wear and friction)behavior of Ti6Al4V biomedical alloy.In this sense,three different processing routes were studied:conventional casting,hot pressing and selective laser melting.A comprehensive metallurgical,mechanical and tribologicalcharacterization was performed by X-ray diffraction analysis,Vickers hardness tests and reciprocating ball-on-plate wear tests ofTi6Al4V/Al2O3sliding pairs.The results showed a great influence of the processing route on the microstructural constituents andconsequent differences on hardness and wear performance.The highest hardness and wear resistance were obtained for Ti6Al4Valloy produced by selective laser melting,due to a markedly different cooling rate that leads to significantly different microstructurewhen compared to hot pressing and casting.This study assesses and confirms that selective laser melting is potential to producecustomized Ti6Al4V implants with improved wear performance.

Evaluation of the Circulation Patterns in the Black Sea Using Remotely Sensed and <i>in Situ</i>Measurements

The objective of the present work is to provide an overview of the general circulation features in the Black Sea basin. In order to achieve this, 18 years (1993-2010) of satellite data coming from the Aviso website were analyzed. A description of the general circulation patterns in the Black Sea is first presented. This is followed by statistical analyses of the satellite data in 20 points covering the entire area of the sea. The reference points were chosen as follows: 12 points along the Rim cyclonic current, 3 points inside the Rim cyclonic current, 4 points on the edge of two of the biggest anticyclonic gyres outside the Rim current and one point in the northwestern shelf area of the basin. Rose graphics were drawn for the reference points for winter and summer time. Finally, 9 years of in situ data obtained from the Gloria drilling platform were analyzed and compared with the satellite data. The present study shows that most of the reference points are sensitive to seasonal changes. The current velocities depend mostly on the points location: the points located on the Rim current and on the nearshore anticyclonic eddies present higher values than the ones located in or outside the general circulation features.

An Evaluation of the Main Physical Features and Circulation Patterns in the Black Sea Basin

Having as target the semi-enclosed basin of the Black Sea,the primary purpose of the existing paper is to present an overview of its extensive physical features and circulation patterns.To achieve this goal,more than five decades of data analysis-from 1960 to 2015-were taken into consideration and the results were validated against acknowledged data,both from satellite data over the last two decades and in-situ measurements from first decades.The circulation of the Black Sea basin has been studied for almost 400 years since the Italian Count Luigi Marsigli first described the“two-layer”circulation through the Bosphorus Strait in the year 1681.Since climate change projections for the Black Sea region foresee a significant impact on the environment in the coming decades,a set of adaptation and mitigation measures is required.Therefore more research is needed.Nowadays,the warming trend adds a sense of immediate urgency because according to the National Oceanic and Atmospheric Administration’s National Centre for Environmental Information,July 2020 was the second-hottest month ever recorded for the planet.Its averaged land and ocean surface temperature tied with July 2016 as the secondhighest for the month in the 141-year NOAA’s global temperature dataset history,which dates back to 1880.It was 0.92°C above the 20th-century average of 15.8°C,with only 0.01°C less than the record extreme value measured in July of 2019.

COVID-19 impact on the liver

The coronavirus disease 2019(COVID-19)pandemic imposed arestructuring of global health systems by rethinking spaces used for the care of these patients and the additions of intensive care,infectious diseases and pneumology departments.This paper provides evidence on the presence of severe acute respiratory syndrome coronavirus 2 in hepatocytes and its direct cytopathic activity,as well as the degree of liver damage due to drug toxicity,inflammation and hypoxia in COVID-19.A review of clinical trials has quantified liver damage through both pathology and biochemistry studies.Additionally,we briefly present the results of a study conducted in our clinic on 849 patients admitted for COVID-19 treatment,of which 31 patients had pre-existing chronic liver disease and 388 patients had values above the normal limit for alanine aminotransferase,aspartate aminotransferase,and total bilirubin.It was observed that patients with abnormal liver tests were significantly statistically older,had more comorbidities and had a higher percentage of unfavourable evolution(death or transfer to intensive care).The conclusion of this paper is that the main causes of liver damage are direct viral aggression,coagulation dysfunction and endothelial damage,and patients with impaired liver function develop more severe forms of COVID-19 which requires special care by a multidisciplinary team that includes a hepatologist.

An Ecological Assessment of the Pollution Status of the Danube River Basin in the Galati Region—Romania

Physico-chemical parameters and bio-contamination assessment through protozoan cysts and helminths eggs were carried out from the period of June to September 2010 in order to appreciate the pollution of the Danube River Basin in Romania. It recorded a higher tenor in Magnesium ion (60 mg/L) with respect to the calcium ion (20 mg/L). Other ions identified at substantial proportions were iron (1.459 mg/L), manganese (6.583 mg/L), phenol (12.780 mg/L) and Aluminium (0.0441 mg/L). Twenty one ciliated protozoa were identified in our analysis of water in the Danube River. Prominent was the presence of Caenomorpha medusula and Metopus ovatus which are indicators of polysaprobity. Resistant forms of enteropathogenic protozoa were present in our samples. These are Cryptosporidium sp (65 oocysts/l in August), Entamoeba histolytica (22 cysts/L in September), Giardia sp with 30 cysts/L in August. The helminths identified were Ascaris lumbricoides, Clornochis sinensis, Diphyllobothium latum, Enterobius vermicularis, Heterophrys heterophrys, larva of strongiloides stercoralis and Taenia sp. There is a low impact of natural depollution mechanisms which can functionally reduce the impending effect of the communicable diseases that are being transmitted by humans who constantly explore this aquatic medium during their leisure or economic activities.

An Intelligent System for a Resource Allocation Problem Based on Fuzzy Reasoning

The development of the assistive abilities regarding the decision-making process o fan Intelligent Control System （ICS） like a fuzzy expert system implies the development of its functionality and its ability of specification. Fuzzy expert systems can model fuzzy controllers, i.e., the knowledge representation and the abilities of making decisions corresponding to fuzzy expert systems are much more complicated that in the case of standard fuzzy controllers. The expert system acts also as a supervisor, creating meta-level reasoning on a set of fuzzy controllers, in order to choose the best one for the management of the process. Knowledge Management Systems （KMSs） is a new development paradigm of Intelligent Systems which has resulted from a synergy between fuzzy sets, artificial neural networks, evolutionary computation, machine learning, etc., broadening computer science, physics, economics, engineering, mathematics. This paper presents, after a synergic new paradigm of intelligent systems, as a practical case study the fuzzy and temporal properties of knowledge formalism embedded in an ICS. We are not dealing high with level reasoning methods, because we think that real-time problems can only be solved by rather low-level reasoning. Solving the match-time predictability problem would allow us to build much more powerful reasoning techniques.

Analysis of the Mamaia Bay shoreline Retreat with Hard and Soft Protection Works

Integrated Coastal Zone Management is a complex concept that involves various economic, social and environmental factors. There are often conflicting approaches to these factors. Furthermore, when it is decided to implement structural works in the coastal area, it must be taken into account the particularity of the area, the way in which it is developed and the type of work to be done. The Gulf of Mamaia in the Romanian Black Sea coast is the target of structural changes through the implementation of an extensive coastal rehabilitation program. The works made are of “hard” type and aim to change the shore line configuration. From this perspective, the target of the present paper is to make an analysis between the type of work that is being carried out and another kind of "soft" work aiming especially to favor the ecological reconstruction of the area and the approach of an environmentally friendly concept. Thus, we propose to analyze the two types of works with a view to apply the Bruun rule in order to mitigate the effect of the increase of the sea level and to prevent the shoreline retreat.

Can Air Quality be Influenced in Coastal Areas by Shipping?

The problem of pollution is a topical issue at global,regional but also at the local level.Starting from this idea,the question arises whether the coastal region in the North-East of the Black Sea is affected by the emissions resulting from the combustion of marine fuels in large ship engines,which manage to set in motion floating buildings intended for the transport of goods and passengers.This paper wants to evaluate the variation of the air quality indicators in the coastal area of Romania,taking into account the contribution that the ships by their number,size and destination can have on these qualitative factors.Such an approach is needed from the perspective of the more than 500,000 inhabitants possibly affected by the effects with which this industry is accompanied.As the Black Sea active fleet is already old,as its ages year by year,the premises for the need for this study can be set up.As in other regions,drastic measures are taken in order to reduce the effects of pollution due to such economic activity,the assessment of the effects that this industry produces in inhabited areas becomes necessary.In order to carry out this study,air quality data from the database provided by the National Air Quality Monitoring Network of the Workshop on the calitateaer.ro site were evaluated.

Comparative Analysis of the Methods Used for Active Power Filtering in a Grid-Connected Photovoltaic System

This paper presents a comparison of the results obtained from the integration of the photovoltaic system to the electrical grid through the Active Power Filter.The innovative aspect of this article consists of the elaboration of 4 models in Matlab/Simulink for 4 methods of control of the Active Power Filter introduced between the photovoltaic system and the alternating current grid and the highlighting of the performances obtained regarding the quality and quantity of electricity transferred for each control method in part.Following the analysis of the results,it was found that by using the Indirect Control(CI)method of the Active Power Filter,the best results are obtained THDu=3.24%,THDi=2.46%if the photovoltaic system produces a larger amount of energy than the nonlinear load,and by using the methods of control of the Active Power Filter Synchronous Reference Frame(DQ)and Instantaneous Power(PQ)the best results are obtained:THDu=3.22%,THDi=5.26%for the method(DQ)and THDu=3.41%,THDi=5.17%for the method(PQ)if the photovoltaic system produces a smaller amount of energy than the nonlinear load.

Power Quality Comparative Analysis between UPF and SAPF

This paper makes a technical analysis of the converter’s topologies that are conventionally employed in three-phase three-wire in increasing the power factor and harmonics eliminating,namely unit power factor(UPF)and shunt active power filter(SAPF)and highlights the improvement of energy quality in the supply network.The paper highlights that the mathematical model of the three-phase PWM rectifier in the dq coordinate system is similar for both configurations.The structure of the control schemes of the two topologies for increasing the energy quality is similar by transformation of three-phase stationary coordinate system(a,b,c),to synchronous rotating(d,q)coordinate system that synchronously rotates with the fundamental voltage of the grid.Theoretical analysis and simulation results show that the control in synchronous rotating coordinate system has high power factor and low THDi for the both topologies.

Analysis by Indicators Performance of the Conceptual Structures mCCHP-SE Using Renewable Energy Sources

This paper refers to an integrated mCCHP （micro-combined cooling heat and power） systems dedicated for isolated residents with energetic independence. The only energy sources are wood pellet and solar energy. The proposed trigeneration system is based on mCHP （micro-combined heat and power） unit with Stirling engine, photovoltaic panels, thermal solar collector and pellet boiler. The proposed mCCHP system utilizes the exceeding amount of heat in the summer for producing the necessary cooling. A residential building with known energy consumption is determined load curves that must be covered by mCCHP system. The paper analyzes four structures of trigeneration systems with thermal activation chiller and two structures of trigeneration systems with mechanical compression chiller. Performance indicators are determined based on energy balance equations for each variant. It compares the performances and establishes the best option.

Comparative Analysis of Sonar Heads Drive Systems

This paper is dealing with a comparative analysis, from technical point of view of the solutions with the highest potentiality utilized in sonar heads drives. Even though the use of DC servomotors is a convenient solution for most customers, from some modem analysis criteria points of view, this type of drive system has a low reliability and a greater impact on the environment, compared to AC servomotors. From this class of AC servomotors, high behaviors, in such an application, have stepper motors and electronically commutated motor （brushless DC）. That is why, analysis in this paper, balances these two classes of AC servomotors. The systems performed are analyzed in Matlab/Simulink and PowerSim environments.

Energy Efficiency of Washing Machines

This paper makes a technical analysis of the methods to increase the energy efficiency of washing machines for student education.Starting from the definition given by the Energy Efficiency Index,the present analysis proposes two methods for increasing the energy efficiency of the washing machines by modifying the standard annual energy consumption(SAEc)and by modifying the annual energy consumption(AEc).These two methods are made per kilogram of clothes for washing machines from the same brand in different energy classes and for washing machines of two different brands.The models analyzed were chosen according to their energy rating A++and A+++.The results of this analysis propose the energy savings as an energy indicator to inform buyers in choosing a brand and energy class of the washing machine.

Stand-Alone Wind Power System Operating with Different Storage Structures

This paper deals with control method related to a wind system operating in stand-alone applications. The stand-alone wind system is composed of three energy transfer subsystems： wind generator subsystem （wind turbine and electrical generator）, energy storage subsystem, respectively, specific local network subsystem （controlled loads）. This wind power system performs in the same time the maximization of wind energy conversion and the power balance between produced and required power. Three structures of the energy storage subsystem, based on buffer battery operation and/or capacitor voltage control, are discussed. The simulation results show that the proposed stand-alone wind power system ensures a good management of the local energy request. The design of the structures is analyzed in Matlab/Simulink environment, using PowerSim toolbox.

Theoretical Study and Performance Analysis of an Adsorption Chiller

The thermodynamic cycle for an adsorption system is presented inp-T diagram. In order to investigate the performance of the adsorption system, a lumped parameter transient model of the chiller is developed, in order to predict the behaviors of the adsorption chiller system and find the influence of working conditions on its operation. For the working process of the main components of the system, including adsorber, condenser and evaporator, the coupled unsteady equations were set up for each stage. The model was then solved using stable numerical methods from EES （equation engineering solver）, and the performance of the adsorber and condenser/evaporator of the system was analyzed. The condensation, evaporation and adsorber temperature values as well as the adsorption ratio and desorption ratio were obtained as function of operating time. Also, the coefficient of performance was analyzed in function of the heat source temperature and the cooling source temperature.

Harvesting Offshore Renewable Energy an Important Challenge for the European Coastal Environment

In the last decades significant changes in the climate are noticed and it becomes obvious that these dynamics are strongly influenced by recent human development.From this perspective,there is an increasing concern regarding the possible evolution of the climate and various possible scenarios have been designed and analysed.Thus,in 2014 the Intergovernmental Panel on Climate Change(IPCC)adopted the Fifth Assessment Report,where the concept of Representative Concentration Pathway(RCP)was introduced for climate modelling.This is a greenhouse gas concentration trajectory labelled after the expected values of the radiative forcing by the end of 2100.