bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of waste oil purification technology on a heating installation of an industrial hall
Authors: Dragne Mihai , Pop Elena , Pîşă Ionel
Published: July 2020

The paper proposes the development of an experimental model of boiler using waste oil revitalized with bentonite, for heating an industrial hall. The main objective is to present a new perspective on the use of waste oils, a framework in which it no longer presents a danger to the environment and to human health, as well as their energy use from an economic and ecological point of view. Experiments were performed to determine the adsorption of the impurities from the waste oil. One of the experiments is to compare the combustion of the revitalized waste oil with the combustion of raw waste oil. The results show improvements in the combustion process and decreases of the pollutant emissions for revitalized waste oil. The CO concentration decreased on average by 52% when and the NOx concentration increased by 57% due to the increase of temperature in the furnace in the case of burning purified oil. The experimental installation is adapted on an industrial hall.
Combustion Experiments On A Solid Fuel With Low Sulphur Content
Authors: Prisecaru Tudor , Adam Adrian , Mihăescu Lucian , Pîşă Ionel , Pop Elena , Prisecaru Malina , Berbece Viorel , Dragne Mihai
Published: July 2020

Research was carried out at the experimental installation defined by the 2 MW furnace pilot from the Politehnica University of Bucharest and ICEMENRG institute who was involved for measurements. The purpose of the experimental study is to confirm that the use of a coal with low sulphur content S<0.08% is possible without the use of sulphurpurification installations for industrial purposes. But, the high moisture content of the coal has imposed the problem of its compatibility with a certain milling technology. The pilot plant is equipped with fan mill and pre-drying tower. Under these conditions, this installation allows the grinding of fuels with high moisture content. The experiments focused on the process of ignition, combustion and pollutant emissions, with the exemplification, in particular, of the emission of sulfur dioxide. Also, the outbreak temperatures and the slugging temperature were monitored. For this purpose, the outbreak of the pilot boiler was equipped with all the equipment necessary to follow these parameters. The experiments have shown positive aspects to the burning of this fuel, thus laying the foundations of future tests at industrial installations (first of all, the power plant from Deva is considered).
Structural and Technological Features of an Installation for Recovery of End-of-life Automobile Tires
Authors: Rasheva Violeta , Komitov Georgi , Binev Ivan , Valtchev Georgi
Published: July 2020

Automobile tires are one of the generated wastes from the road transport. According to an EU directive after 2006, end-of-life tires are subject to controlled collection and storage by traders. Direct incineration is unacceptable due to high levels of hazardous emissions. In addition to the high rate of depletion of natural resources, and in line with the “sustainable development” model, it is appropriate to create new advanced technologies for the proper utilization of natural resources through the reuse of end-of-life products. The pyrolysis technology of decomposition of raw materials is an innovative technology for production of fuels and metals from the disposal tires. This technology shows a reduced risk to public health and reduced levels of harmful substances in flue gases, has low operating costs and does not require separate waste collection. This paper focuses on the structural features of the pyrolysis installation for used automobile tires recycling. The installation has been implemented into production and has a capacity of 1 ton of end-of-life tires per hour. The result is 400 kg of liquid fuel, 400 kg of carbon and 100 kg of metal waste per hour.
A combined approach for assessment the functionality of photovoltaic modules in real-world operation
Authors: Nedelchev Ivaylo , Zhivomirov Hristo
Published: July 2020

The energy production from the solar photovoltaic power plants is highly dependent on the meteorological and physical conditions such as solar radiation, ambient and panel’s surface temperature, inclination of the photovoltaic (PV) panel construction etc. The I-V curves are the most important for estimation the functionality and production of each PV panel, as well as finding the maximum power point (MPP) of it. Because of the continuous generation of energy, the silicon crystal of the PV modules begins to depreciate and this decreases the energy production. In real-world operating conditions, revealing the energy state of the PV panels is the main point for estimating the PV panels’ efficiency. Furthermore, one complete approach, including electrical measurements and temperature distribution information over the PV panels’ surface, can reveal the risky elements (subcells) and provide data for prevention damages and working interruptions. This paper presents a method for PV monitoring in which conventional electrical instrumentation devises and thermographic camera are used, in order to estimate the real physical state of the PV panels’.
Predictive maintenance of photovoltaic plants using multirotor drones with automatic recharging system of Li-Po batteries
Authors: Pleşca Vasile , Purece Cristian
Published: July 2020

Creating the correct maintenance of the strings that form the electric generators, from a photovoltaic park, it requires scanning of the equipment with thermal vision cameras, in the visible and infrared field, at an optimum angle determined precisely for each location depending on the geographic position and the architecture of the power station. In general, this angle is difficult to maintain from the ground so it is necessary to mount the cameras on a support, or most efficiently on a multi-rotor drone that is very stable and easy to handle. Maintenance using multi-rotor drones and heat sensitive cameras is no longer a novelty and has multiple advantages: low costs, minimization of work accidents, and the data acquired can be analyzed in real time or can be stored for later analysis. But this process also has disadvantages: limited flight autonomy of drones, generated by the hard development of battery technology and a small number of specialized personnel in this field. To minimize these disadvantages, we have developed an automatic recharging system of batteries, without disconnecting them, which allows the automation of the scanning process and offers the possibility of taking control of the drones and from a distance.
IoT solution for monitoring indoor climate parameters in open space offices
Authors: Udrea Ioana , Gheorghe Viorel Ionut , Cartal Laurentiu Adrian , Duminica Despina , Petrache Silviu , Apostolescu Tudor Catalin , Kraus Valeru Friedemann
Published: July 2020

Although there are numerous high performance BMS (Building Management System), which monitor the indoor climate parameters, data access, sensor positioning, and other aspects may not be under control. On the other hand, IoT (Internet of Things) is experiencing exponential growth, as more and more devices and sensors are connected to the cloud. Thus, a sensor monitoring solution for indoor climate parameters was developed. The proposed solution is not expensive, and it is based on a Raspberry Pi board endowed with temperature, humidity, and pressure sensors. The developed application reads the values detected by the sensors, processes the date, and afterwards transmit the information to the IoT ThingSpeak platform. The large area is characteristic of open space offices, so the influence of radiant walls is small, and the operative temperature can be approximate with air temperature. This type of building is conditioned by the air conditioning system, so the air speed in this indoor environment is usually low and could be approximated by the design. So, with the data read by the developed solution the thermal comfort parameters can be approximated. If inadequate values are found, teams that carry out complex and precise measurements could be sent to the site. To achieve this goal a PMV calculator software is developed. Its validity is tested in accordance with the European standard ISO 7730. After that, the PMV computer is used with data read from sensors. Both the data read from the sensors and the newly calculated PMV are sent to the ThingSpeak IoT platform.
Energy and exergy analysis of a flat plate collector using collector test equations
Authors: Gheorghian Adina-Teodora , Prisecaru Tudor , Ciobanu Mihaela Cristina
Published: July 2020

This paper presents the energetic and exergetic analysis of a widely used flat plate collector based on the collector testing equations. The evaluation of the performances of the collector is done under the climatic conditions corresponding to a typical meteorological year in Constanta, Romania. Using a dimensionless-geometric optimization criterion, the climatic conditions for which the energy efficiency and exergetic efficiency have the maximum values are determined. The optimal weather conditions for the collector's operation are: the solar irradiation of 916 W/m2 and the air temperature of 15.4 °C; under these conditions, the energy and exergy efficiencies of the collector are 57% and 4.8%, respectively.
Process characterization and energy balance of air wood residues gasification using continuous operated pilot scale reactor
Authors: Gheorghe-Bulmau Cora , Nicoleta Tirtea Raluca , Ionescu Gabriela , Marculescu Cosmin
Published: July 2020

This work aimed to study the effect of gasification process operating conditions on syngas composition and properties, and process efficiency. A rotary kiln gasifier lab-scale pilot plant with capacity ≅ 30 kg/h and a power of 30 kWe was used for gasification tests applied to cherry wood at different loads, for a temperature of about 600°C, while the air was used as gasification agent for all tests. The syngas composition was measured and analyzed. The results have shown that conversion of wood cherry through gasification lead to a lean fuel gas of 3.5 MJ/Nm3 and installation characteristics have a major influence both on process and syngas properties. This is happened because the rotary kiln gasifier allows some air infiltrations, and consequently a high N2 content in the syngas composition. The energy balance of the cherry biomass gasification processes was calculated. It was found also that gas density varies slightly from 1.26 to 1.43 kg/m3, while the specific heat of the gas varies from 1.04 to 1.34 kJ/kgK.
The generation of a mathematical model of the biogas production process from organic municipal solid waste
Authors: Temirbekova Marzhan , Aliyarova Madina , Iliev Iliya , Yelemanova Aliya , Sagintayeva Saule
Published: July 2020

This paper justifies the efficiency of the biogas collection and utilization at the MSW (municipal solid waste) landfill in Almaty with the installation of several modern biogas plants. The optimal mode of processes occurring in a biogas plant is determined by computer generated simulations. Mathematical model parameters were identified to describe biochemical processes occurring in a biogas plant. Two approaches are used to resolve the mathematical model: the finite-difference method for solving the system of differential equations and simulation modeling by using the Any Logic package. A program is written in the algorithmic language C ++. Numerous calculations were carried out, the results of which are presented in curves and their qualitative picture is consistent with the ongoing processes. The created computer program allows to make a preliminary forecast of anaerobic fermentation occurring in the bioreactor depending on volume of the substrate, methane microorganisms and temperature conditions.
Sorption Characteristics of Bulgarian Penny Buns (Boletus Edulis)
Authors: Durakova Albena
Published: July 2020

The present study determined the sorption characteristics of Bulgarian penny buns (Boletus) for eight water activities in the 10 % 90 % range and at three temperatures, of 10 °С, 25 °С and 40 °С. The coefficients of the modified Oswin, Chung-Pfost, Halsey and Henderson models were obtained statistically. The modified Halsey model is recommended as a description of adsorption and desorption isotherms since it corresponds to the criteria for model assessment and suitability. Via BET model linearization, the values of the monolayer moisture content for water activity of aw > 0.5 and temperatures of 10 °С, 25 °С and 40 °С were established. The approximate physico-chemical composition of Bulgarian penny buns (Boletus) – moisture content – 10.80 %, protein – 32.23 %, carbohydrate 0.99 %, fat – 6.62 %, ashes – 6.20 % - was also determined.
Structural, kinematic and kinetostatic analysis of a manure spreader equipped by a mobile platform with articulated elements
Authors: Popa Lucretia , Moise Stefan-Iulian , Moise Victor , Stefan Vasilica , Ganea-Christu Ioan
Published: July 2020

Organic fertilization involves working with machines by a special construction, suitable for the material to be spread, machines that have, in most cases, chain conveyors with scrapers attached to the chains. In some cases, the conveyor chain may break, due to the jams, and the need for manual unloading of the bunker (bucket) appears, which requires a great physical effort, the unloading being made by the operator, using a shovel. The construction of the platform using mobile, articulated elements would greatly facilitate the unloading at the bottom of the bunker and would eliminate the physical effort of the operator. This article presents the structural, kinematic and kinetostatic analysis of a mechanism designed for actuating a mobile platform, which is part of a manure spreader, composed of articulated elements driven by hydraulic cylinders.

For the kinematic analysis of the mobile element platform’s mechanism, calculation procedures written in the Matlab syntax are used.

After the kinematic analysis of the mechanism, the kinetostatic analysis is performed, i.e. the determination of the reactions from the kinematic couplings, as well as the hydraulic force from the hydraulic cylinder. The results can be used for dimensional verification of the mechanism components, thus contributing to the optimization of the mechanism.
Study of the compression behaviour of grape seeds using the Finite Element Method
Authors: Vasilachi (Baltăţu) Carmen , Biriş Sorin-Ştefan , Gheorghe Gabriel
Published: July 2020

It is important to know all phenomena that occur during compression of grape seeds because are very complex. Studying these phenomena can help us in increasing the performance of the equipment. Also for the pressing of oilseed materials, it is helpful to understand the compression behavior of grape seeds. The purpose of this study is to find how the stress and deformation propagate in grape seeds during the compression process. Therefore, we used an advanced engineering method named finite element method that shows the propagations of stress and strain fields in grape seeds. In this paper, we made a two dimensional model of grape seed and we analyzing the dispersion of stress and strain with a dedicated software FEM. In the end, to validate the FEM model we made a compression test on grape seeds using a Hounsfield unit. This study is for highlighting the importance of the orientation of the grape seeds during the pressing process to reduce the energy consumed.
Mathematical modelling of the drying process of sugar beet pulp with macro and microelement additions in order to improve the feed quality
Authors: Nagy Elena Mihaela , Coţa Constantin , Gyorgy Zoltan , Deac Teodora
Published: July 2020

In this paper a kinetic study is performed on the drying process of beet pulp with additions of macro-elements (Ca2+, Mg 2+, PO42+) from hydrated lime, hydrated dolomite lime, phosphoric acid and microelements (Co2+, Zn 2+, Fe2+, Mn2+), with the purpose of obtaining premixes with substantially improved value for animal feed. The experimental measurements made served to elaborate the mathematical model by means of which the speed with which the drying process is carried out is described, thus being able to calculate the stationing time of the material in the dryer. The equations for calculating the stationary time of the material in the dryer can be used for designing dryers (sizing them).
Kinetostatic analysis of a scissor jack mechanism powered by a tetrad RRR-Ta-RRR
Authors: Moise Victor , Dugaesescu Ileana , Popa Lucretia , Ungureanu Liviu , Moise Ştefan-Iulian
Published: July 2020

In a paper previously published by the authors, kinematic analysis of a jack mechanism driven by a motor tetrad was done. For the actual design of the mechanism, the forces and moments acting on the kinematic elements that are part of it must be determined. Also, the driving force in the hydraulic cylinder must be determined, so that the mechanism works in good conditions, for a certain technological task imposed by the design theme. The present paper makes the kinetostatic analysis of the mechanism studied, from the kinematic point of view. Therefore, the reactions in the kinematic couplings of the mechanism, as well as the driving force of the hydraulic cylinder, are determined. In order to determine the reactions of the kinematic couplings, as well as the driving force of the hydraulic cylinder, the masses of the elements, the moments of mechanical inertia, as well as the load force acting on the jack were considered. The results of the calculations were graphically represented, in reaction patterns. In order to verify the correctness of the calculations, the balance force (the hydraulic cylinder motor force) was determined by both the kinetic and the virtual power method, and the results are the same.
Experimental testing of a helical rotor for compost distribution
Authors: Stefan Vasilica , David Ladislau , Ciuperca Radu , Zaica Ana , Nedelcu Ancuta , Suvac Albert
Published: July 2020

It is well known that a manure spreader must be able to apply manure consistently, effectively and uniformly over the time. An overapplying doze will cause serios environmental problems (pollution) and a sub-applying doze will not contribute to plants growth and the applying of the fertilizer will be a loss. Corroborate with others problems such as maintaining a constant tractor speed, a constant rotational speed of the rotor, a constant and continuous flow of the material make the manure spreading machines an important subject for study and continuously improving . The propose of this study is to test a vertical helicoidal rotor for manure spreading in order to improve the machine distribution uniformity. The relation between the rotor position and rotation sense is a definitory issue for the machine performance. In order to achieve a high distribution uniformity a single helical rotor is tested and a series of possible situations of placing four rotors on the machine are analyzed. The optimal solution is given by two indicators: uniformity of spreading and distribution width. The test were made with an helical rotor having the following characteristics: high=1,1 m, maximum diameter of helical spiral=0.345 m, minimum diameter of the helical spiral= 0.114m, helical pitch=0.3m, inclination angle = 15°. After analyzing four possible situations it is observe that the combination of the maximum uniformity with minimum distribution with is the optimal solution. Experimental were carried out with compost and can be repeatable with others type of solid organic fertilizers, but a new calibration should be done. It is desirable that a trapezoidal, oval or triangle pattern with uniform sloping sides to be achieved. Because most of the spreaders actually produce an oval or triangle distribution pattern it is necessary subsequent passes that increase the time for fertilization operation.
Simulation regarding the forward part of underwater remotely operated vehicle designed for research in maritime and river districts
Authors: Nedelcu Andra-Teodora , Buzbuchi Nicolae , Stan Liviu-Constantin , Lucian Dumitrache Mihail
Published: July 2020

Over the last few decades, underwater mechanical system became a necessity for ocean research and exploration. The necessity of this type of equipment provides a new type of marine platforms in different areas of oceanographic research. Until this moment, the underwater vehicles have developed in different shapes, sizes and means of propulsion. Take into consideration these characteristics, we could determinate the type and mission of the vehicle. In this paper we investigate the problem regarding the pressure exerted of remotely operated vehicle. The remotely operated vehicle is designed in order to achieve different mission regarding the surveillance in lakes, harbors and maritime environment. This mission can take place through a remote control system placed onshore or on seaborne platforms. To improve the endurance of remotely operated vehicle, we performed a simulation study during which we compare the drag forces acts on the underwater vehicle according to its shape. Using SolidWorks program to create the body simulation vehicle and Ansys CFX to realise the simulation, this paper present the result simulated for the forward part of the vehicle.
The strong connection between marine engineering and marine environmental education within a marine cluster
Authors: Sundri Mirela Iuliana , Memet Feiza
Published: July 2020

Marine Environmental Education (MEE) is a vital activity, since the marine environment is impacted by industrial and technologies involved in this sector. MEE is in strong connection with marine engineering. The players from this industry have to comply with environmental protection protocols and conventions. A marine cluster is a good way of approaching issues specific to the exploitation of resources of the sea. In the present, a particularity of marine pollution is that in enclosed seas (such as Black Sea is) and on coastal areas, the pollution is higher than in the open ocean. In order to fight with this reality, it is also vital to increase the public environmental awareness throughout specific education, not only to train specialists in this respect. This paper is providing the pylons on which MEE relies. From this paper will succeed how the objectives of MEE (awareness, knowledge, attitude, skills, participation) and its specific actions (environmental education and training, involvement, bringing people together) are supported by a marine cluster. The most important result of this study can be stated as: processes developed within MEE will enforce the involvement of specialists in solving marine pollution issues and will rise the environmental consciousness of communities, in a framework provided by a cluster oriented towards MEE.
Dynamic behaviour of pneumatic actuators in open-loop controlled by proportional valves
Authors: Cococi Valentin Nicolae , Safta Carmen-Anca , Călinoiu Constantin
Published: July 2020

The development of proportional and servo-mechanisms hydraulic control technique offered the premises of the development of pneumatic control, too. Despite the disadvantages of the nonlinearities appeared in the pneumatic systems (air compressibility being one of the causes), the new generation of proportional equipment made it possible to have a good quality pneumatic control system in our days. The goal of the paper is to demonstrate, by using numerical simulation technique, that the proportional valves used in pneumatic actuator drives occur at a good system dynamic at a reasonable cost as against to the directional control valve as it usually used in pneumatic actuator drives.
Assessment and risk prevention of air pollution in urban sites
Authors: Panaitescu Mariana , Panaitescu Fanel-Viorel , Panait Cornel , Bardasu Octavia , Merla Viorica-Ani
Published: July 2020

Atmospheric pollution limitation has evolved and evolves continuously, depending on the better knowledge of the harmful effects of the different atmospheric pollutants. The main elements that have led and lead to the continuous revision of the norms are the climatic changes and acid rain associated with atmospheric pollutants. In this context, the paper presents the following aspects: two monitoring regimes aims to evaluate and prevent air pollution in urban areas; was chosen as a monitoring location Constanta city, with strategic points exposed to the risk of pollution. For the monitoring of emissions in these locations, a selfemployed emission analyzer was used. Where there are risk areas, exists a risk analisys with vulnerable locations and values of emissions’s concentrations. There are monitoring CO, CO2, NO2, SO2 emissions and PM2.5 and PM10 in air of urban sites which are exposed to the risk of pollution. Finally, the recorded values are below the maximum permissible limit. The conclusion is that pollution in urban sites can also be a danger to neighboring rural settlements, if there is no strict monitoring thereof.
More on Smart Cultural Landscapes: technicalities of the planning processes
Authors: Calcatinge Alexandru
Published: July 2020

This paper will build upon my previous smart cultural landscapes research, by offering a technical overview of the planning processes that the policies are based on. In this respect, I will discuss, in an analytic manner, how the argumentation process should take place from a cultural landscape study. This will take into consideration the proficiencies of a planning professional, the smart characteristics of a cultural landscape policy or study and the relevant steps that should be taken to effectively solve the local rural or urban cultural landscape specific issues. The anticipated results would be to establish a well-known place of cultural landscape studies amongst the local rural and urban development processes.
Mathematical Description of Sequencing Batch Reactor operation of treatment of wastewater with low concentration of organic contaminations
Authors: Gogina Elena
Published: July 2020

The paper is oriented towards the study of certain small wastewater-treatment plants, in particular the study of some treatment processes where the wastewater has low concentration of organic contamination. The primary goal of this paper was to obtain the characteristics of a biological treatment system which comply with the laws of enzyme kinetics. The design formulas of the Sequencing Batch Reactor with an inflow of wastewater and low concentration of organic contaminations has been obtained.
Determination of the minimum wind speed leading to the galloping of conductors
Authors: Zhamanbaev Muratkali , Ilieva Diana , Abitaeva Rakhimash , Ongar Bulbul
Published: July 2020

The object of research in this paper is the split phase of overhead power lines. The study of the aeroelastic instability of the icy conductors of the split phase for a multi-span system has already been explored using the method of determining the Hurwitz stability criterion. In multi-span systems, where conductors are interconnected through a garland of insulators, the garlands themselves are involved in an oscillatory process. As a result of this, mutual influence of adjacent spans is observed energy is transferred from one span to another. The paper investigates the aeroelastic instability of the icy conductors of the split phase in the anchor span, which is characterized by two intrinsic features: the attachment point of conductors on the supports is fixed and mutual effects between adjacent spans are not observed. The study of motion instability is carried out by the first approximation method, that is, on the basis of linearization of the nonlinear equation at the equilibrium point and further investigation of the linearized equation in the vicinity of this point. The results of the study are based on the novelty of the carried out experiments - taking into account the peculiarities of the anchor span and the findings based on the analysis of empirical data.
The effect of thermal pre-treatment on cassava rhizome properties for utilizing as green fuel in gasification
Authors: Sirinwaranon Punchaluck , Atong Duangduen , Sricharoenchaikul Viboon
Published: July 2020

Cassava rhizome (CR) was torrefied to provide superior solid fuel quality for further gasification process. The torrefaction was carried out in the absence of oxygen at 220, 240, 260, and 280°C with a fixed residence time. Solid fuel after torrefaction has a higher calorific value from that of reduced volatile matters. The optimum energy yield of torrefied CR is 88.16% at 260°C. The heating value of 20.86 MJ/kg for a torrefied product can be achieved compared to 15.37 MJ/kg for untreated CR. The subsequent gasification of torrefied CR at temperature of 800°C yielded the highest gas product of 65 wt.%. The carbon and hydrogen conversions into CO and H2 were 14.28% and 29.95%, respectively. Synthesis gas (syngas) from the conversion maintained the H2/CO ratio of around 2–2.50, which is suitable for the Fischer–Tropsch process or can be used as the feedstock for petrochemical industry.
The effect of curcumin coated electrode on hydrogen production through water electrolysis
Authors: Satrio Willy , Winarto  , Sugiono  , Wardana I.N.G
Published: July 2020

Hydrogen as the most cleanest energy source promise polutant free combustion. However, hydrogen production process still have negative impact on environment. Water electrolysis as one of hydrogen production process leave toxical gas residue and if the catalyst used in the process is metal catalyst it will leave metal waste which have potential to pollute soil and water. Curcumin as polyphenol antioxidant have potential as electrocatalytic agent due to its electron donor behavior. Curcumin loaded aluminum electrode coated by mechanical coating technique using water as solvent perform better as electrode compared to non-coated electrode. Curcumin coated cathode, anode and both electrode produce more hydrogen in shorter time than non-coated electrode. Curcumin electron donor increase the current density flows through the electrodes which is lift up the efficiency of water electrolysis process.
Compartmentalization and polarization studies of a Plant-Microbial Fuel Cell assembly with Cynodon dactylon
Authors: Pamintuan Kristopher Ray S. , Reyes Carl Samuel A. , Lat Dheya Kristalyn O.
Published: July 2020

Plant-microbial fuel cells (PMFCs) are a class of renewable biomass energy that relies on the rhizodeposition of plants to generate power. In this study, the optimization of electrode spacing, number, and combinations were studied to maximize the power output of a soil PMFC growing Cynodon dactylon. To achieve this, compartmentalization tests were carried out as well as polarization. The anode-cathode distance was found to produce the highest voltage at 3 inches apart, wherein a smaller gap resulted to lower power, and a slight increase in the gap did not result to a loss of power. The use of multiple electrodes was also examined, and the results have shown that maximum power was obtained at inter-electrode distance of 18 cm. Smaller gaps registered lower voltages, and larger gaps gave a sudden drop in voltage. The effect of limiting one electrode was also observed. In anode-limiting conditions, it was found that both power and power density were maximum when there are 4 cathodes corresponding to one anode. When the reverse was done, it was shown that both power and power density continuously dropped if there are multiple anodes corresponding to one cathode only. This led to the conclusion that cathode design is more crucial in PMFCs as it utilizes the rate-limiting step. The tests of using multiple paired electrodes to determine the power-power density relationship results to a contradiction of behaviour in MFCs, wherein both power and power density increases as the electrode surface area is increased. These results are important building blocks to the goal of utilizing PMFCs in the future in larger scales with appreciable power generation.
Simulation of large PV energy facilities with SAM HCPV and PV detailed models
Authors: Boretti Alberto , Nayfeh Jamal , Al-Kouz Wael
Published: July 2020

Here we compare the measured energy production of the solar photovoltaic (PV) energy facilities of Solar Star and Desert Sunlight with the values computed in National Renewable Energy Laboratory (NREL) System Advisor Model (SAM), by using the SAM database for the typical weather, and the different models available, the high concentration photovoltaic (HCPV) model, as well as the PV detailed model. Both models are semi-empirical. The HCPV is the most sophisticated model, permitting the specification of a much larger number of parameters. The detailed PV model is less flexible. The comparison shows that SAM computes winter and summer energy productions that are much closer than what is shown by the experiments, dramatically underrating the seasonal variability. This is due to a solar resource for direct normal irradiance during winter and summer that is much closer to what is shown by other databases, such as Weather Spark, for their incident shortwave solar energy inclusive of seasonal variations, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. The contribution highlights the issue of the mostly missing validation of renewable energy tools, in needs of proper high-frequency simultaneous weather and plant data, both at the system and the level of the individual components, before their use for performance estimations.
Piezomagnetic behavior: experimental observations and multiscale modeling
Authors: Ouaddi Achraf , Hubert Olivier , Furtado Jader , Gary Daniel , Depeyre Sophie
Published: July 2020

This work deals with the study of magnetoelastic coupling in the framework of non-destructive testing. Experimental hysteretic and cyclic piezomagnetic measurements carried out on a dual-phase steel submitted to different magnetic field and stress conditions are reported. The effect of concomitant magnetic field and stress, considering static or variable amplitudes, is discussed. A new multiscale modeling of piezomagnetic hysteresis is finally proposed.
The Antinociceptive Activities of Certain NSAIDS Combinations in Murine Orofacial Test
Authors: Miranda Hugo F. , Noriega Viviana , Sierralta Fernando , Sotomayor-Zárate Ramón , Prieto Juan Carlos
Published: July 2020

Pain models are mostly in rodents and between them formalin orofacial test allow discrimination among antinociception and anti-inflammation. This assay use a formalin solution injected into the upper right lip of each mouse which produces two periods of pain separated by an inactive period. The aims of the present study were to evaluate, by means of the isobolographic analysis, the antinociception and anti-inflammatory activities of the following NSAIDs: dexketoprofen, diclofenac, piroxicam and metamizole in an orofacial. The NSAIDs administered intraperitoneally produced a dose-dependent activity with the following order of potency of the rubbing behavior, in phase I: diclofenac>dexketoprofen>piroxicam>metamizole and in the phase II: metamizole>diclofenac>piroxicam>dexketoprofen. The coadministration of NSAIDs resulted in a synergistic interaction, which according to the value of the potency of the combination (II) presents the following range: dexketoprofen plus metamizole>dexketoprofen plus diclofenac>dexketoprofen plus piroxicam, in phase I and dexketoprofen plus metamizole>dexketoprofen plus piroxicam>dexketoprofen plus diclofenac, on the phase II. Data obtained in this work corroborate that NSAIDs alone or in combination inducing activities by additional mechanism of action supplementary to inhibition of COXs. This fact represent a novel approach that could be used as multimodal management of orofacial pain, since with this treatment strategies, by the reduction of doses, can help to diminish side effects of other dugs such opioids.
Synthesis and Functions of Oligomeric and Multidentate Dipyrrin Derivatives and their Complexes
Authors: Nabeshima Tatsuya , Chiba Yusuke , Nakamura Takashi , Matsuoka Ryota
Published: July 2020

The dipyrrin–metal complexes and especially the boron complex 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) have recently attracted considerable attention because of their interesting properties and possible applications. We have developed two unique and useful ways to extend versatility and usefulness of the dipyrrin complexes. The first one is the linear and macrocyclic oligomerization of the BODIPY units. These arrangements of the B–F moieties of the oligomerized BODIPY units provide sophisticated functions, such as unique recognition ability toward cationic guest, associated with changes in the photophysical properties by utilizing unprecedented interactions between the B–F and a cationic species. The second one is introduction of additional ligating moieties into the dipyrrin skeleton. The multidentate N2Ox dipyrrin ligands thus obtained form a variety of complexes with 13 and 14 group elements, which are difficult to synthesize using the original N2 dipyrrin derivatives. Interestingly, these unique complexes exhibit novel structures, properties, and functions such as guest recognition, stimuli-responsive structural conversion, switching of the optical properties, excellent stability of the neutral radicals, etc. We believe that these multifunctional dipyrrin complexes will advance the basic chemistry of the dipyrrin complexes and develop their applications in the materials and medicinal chemistry fields.

1 Introduction

2 Linear Oligomers of Boron–Dipyrrin Complexes

3 Cyclic Oligomers of Boron–Dipyrrin Complexes

4 A Cyclic Oligomer of Zinc–Dipyrrin Complexes

5 Group 13 Element Complexes of N2Ox Dipyrrins

6 Chiral N2 and N2Ox Dipyrrin Complexes

7 Group 14 Element Complexes of N2O2 Dipyrrins

8 Other N2O2 Dipyrrin Complexes with Unique Properties and Functions

9 Conclusion
From ‘the global’ to ‘the local’: the future of ‘cooperative orders’ in Central Eurasia in times of complexity
Authors: Korosteleva Elena A. , Petrova Irina
Published: July 2020

Living in times of increasing complexity is hard; it becomes even harder with the realisation of diminishing control. How do we adapt our governance to this complexity to ensure peaceful cohabitation of the established and emergent order regimes? This paper contends that it is important to embrace complexity in full, conceptually and practically, by shifting from ‘the global’ to ‘the local’, to understand the pressure of transformational change and to prepare the ground for the emergence of more resilient and cooperative orders. We apply this complexity-thinking, using a 3P analysis, to Central Eurasia, presently a battleground of three competing order-making regimes—the EU, China and Russia. We argue that for more resilient and cooperative orders to emerge, it is essential to understand and enable ‘the local’ and embrace the region in is diversity, to facilitate a more joined-up and bottom-up governance in managing the complexity of a changing world.
Band structure and electronic transport across Ta2O5/Nb:SrTiO3 interfaces
Authors: Miron Dror , Cohen-Azarzar Dana , Segev Noa , Baskin Maria , Palumbo Felix , Yalon Eilam , Kornblum Lior
Published: July 2020

Resistive switching devices promise significant progress in memory and logic technologies. One of the hurdles toward their practical realization is the high forming voltages required for their initial activation, which may be incompatible with standard microelectronic architectures. This work studies the conduction mechanisms of Ta2O5 layers, one of the most studied materials for memristive devices, in their initial, as-fabricated state (“pre-forming”). By separating this aspect and resolving the current mechanisms, we provide the input that may guide future design of resistive switching devices. For this purpose, Ta2O5 layers were sputtered on conductive Nb:SrTiO3 substrates. Ta2O5/Nb:SrTiO3 structures exhibit diode behavior with an ideality factor of n ≈ 1.3 over four current decades. X-ray photoelectron spectroscopy analysis of the interfacial band offsets reveals a barrier of 1.3 ± 0.3 eV for electrons injected from the semiconductor into Ta2O5. Temperature-dependent current–voltage analysis exhibits rectifying behavior. While several conduction mechanisms produce good fits to the data, comparing the physical parameters of these models to the expected physical parameters led us to conclude that trap-assisted tunneling (TAT) is the most likely conduction mechanism. Fitting the data using a recent TAT model and with the barrier that was measured by spectroscopy fully captures the temperature dependence, further validating this conduction mechanism.
Thermodynamics analysis of charged hydrogels for osmotic power applications
Authors: Frank Jodi Ackerman
Published: July 2020

The study shows that polyelectrolytes are strong candidates for energy extraction and provides a framework for their development.
Structure of protonated heterodimer of proline and phenylalanine: Revealed by infrared multiphoton dissociation spectroscopy and theoretical calculations
Authors: Ren Juan , Zhang Xian-yi , Kong Xiang-lei
Published: July 2020

The infrared multiphoton dissociation (IRMPD) spectrum of the protonated heterodimer of ProPheH+, in the range of 2700-3700 cm−1, has been obtained with a Fourier-transform ion cyclotron mass spectrometer combined with an IR OPO laser. The experimental spectrum shows one peak at 3565 cm−1 corresponding to the free carboxyl O-H stretching vibration, and two broad peaks centered at 2935 and 3195 cm−1. Theoretical calculations were performed on the level of M062X/6-311++G(d,p). Results show that the most stable isomer is characterized by a charge-solvated structure in which the proton is bound to the unit of proline. Its predicted spectrum is in good agreement with the experimental one, although the coexistence of salt-bridged structures cannot be entirely excluded.
Multi-domain high-resolution platform for integrated spectroscopy and microscopy characterizations
Authors: Wang Li , Jiang Shen-long , Zhang Qun , Luo Yi
Published: July 2020

In recent decades, materials science has experienced rapid development and posed increasingly high requirements for the characterizations of structures, properties, and performances. Herein, we report on our recent establishment of a multi-domain (energy, space, time) high-resolution platform for integrated spectroscopy and microscopy characterizations, offering an unprecedented way to analyze materials in terms of spectral (energy) and spatial mapping as well as temporal evolution. We present several proof-of-principle results collected on this platform, including in-situ Raman imaging (high-resolution Raman, polarization Raman, low-wavenumber Raman), time-resolved photoluminescence imaging, and photo-electrical performance imaging. It can be envisioned that our newly established platform would be very powerful and effective in the multi-domain high-resolution characterizations of various materials of photoelectrochemical importance in the near future.
Ultrafast infrared spectroscopic study of microscopic structural
dynamics in pH stimulus-responsive hydrogels
Authors: Hong Jian , Zhou De-xia , Hao Hong-xing , Zhao Min , Bian Hong-tao
Published: July 2020

Hydrogels show versatile properties and are of great interest in the fields of bioelectronics and tissue engineering. Understanding the dynamics of the water molecules trapped in the three-dimensional polymeric networks of the hydrogels is crucial to elucidate their mechanical and swelling properties at the molecular level. In this report, the poly(DMAEMA-co-AA) hydrogels were synthesized and characterized by the macroscopic swelling measurements under different pH conditions. Furthermore, the microscopic structural dynamics of pH stimulus-responsive hydrogels were studied using FTIR and ultrafast IR spectroscopies from the viewpoint of the SCN− anionic solute as the local vibrational reporter. Ultrafast IR spectroscopic measurements showed the time constants of the vibrational population decay of SCN− were increased from 14±1 ps to 20±1 ps when the pH of the hydrogels varied from 2.0 to 12.0. Rotational anisotropy measurements further revealed that the rotation of SCN− anionic probe was restricted by the three-dimensional network formed in the hydrogels and the rotation of SCN− anionic probe cannot decay to zero especially at the pH of 7.0. These results are expected to provide a molecular-level understanding of the microscopic structure of the cross-linked polymeric network in the pH stimulus-responsive hydrogels.
Characterization of microwave absorption in carbon nanotubes using resonance aperture transmission method
Authors: Malyuskin O. , Brunet P. , Mariotti D. , McGlynn R. , Maguire P.
Published: July 2020

A new method to characterize microwave electromagnetic (EM) absorption of a bulk carbon nanotube (CNT) material is proposed and experimentally evaluated in this paper. The method is based on the measurement of microwave transmission through a capacitive-resonator aperture (CRA) in a conductive screen loaded with a CNT sample under test. This method allows us to measure microwave permittivity and absorption of thin samples (∼0.1 μm–10 μm thick) with linear dimensions much smaller than the wavelength of radiation in free space. This “minimal” sample requirement restricts the application of conventional microwave characterization methods such as free-space or waveguide permittivity characterization. It is demonstrated that the resonance E-field enhancement inside the CRA leads to strong EM interaction of the microwave E-field with the CNT sample under test, thus enabling high sensitivity and dynamic range (∼5 dB) of the measurement procedure. Another advantage of the proposed technique over conventional non-resonance characterization methods is that in the resonance transmission band, the CRA operation is reflection-less, which leads to a relatively simple qualitative algebraic de-embedding procedure of the material parameters based on the principle of energy conservation. The experimental microwave absorption data of the multiwall CNT samples are presented in the S frequency band (2–4 GHz), demonstrating microwave absorption properties of the multiwall CNT ribbons.
Reversal of uniaxial magnetic anisotropy in Fe/GaAs (110) films driven by surface relaxation: An in situ ferromagnetic resonance study
Authors: Bhagat Babli , Semisalova Anna , Meckenstock Ralf , Farle Michael
Published: July 2020

We report an in situ study of the time evolution of magnetic anisotropy constants of an uncapped 4 nm [∼27 monolayers (ML)] Fe film epitaxially grown on a GaAs (110) substrate at room temperature under ultra-high vacuum (UHV) conditions. The structural and chemical properties are monitored by low energy electron diffraction and Auger spectroscopy with a sensitivity of 0.01 ML. The in situ UHV ferromagnetic resonance (FMR) study over a period of 6 days in <10−9 Pa reveals that there is a slow magneto-morphological transition of the Fe film surface at room temperature. The resonance field measured in situ in the [11−0] direction initially changes at a rate of 0.3 mT/h within 30 h after deposition and later at 0.1 mT/h over 80 h. We determine the time-dependent changes in the in-plane and out-of-plane anisotropy constants and find a sign change in the uniaxial in-plane anisotropy in the first 24 h due to morphological changes at the surface. The in situ FMR measurements and the Auger analysis allow us to exclude changes in the magnetization and anisotropy due to the contamination and oxidation of the Fe film.