bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicon Phthalocyanines as Acceptor Candidates in Mixed Solution/Evaporation Processed Planar Heterojunction Organic Photovoltaic Devices
Authors: Faure Marie D. M. , Grant Trevor M. , Lessard Benoît H.
Published: March 2019

Silicon phthalocyanines (SiPc) are showing promise as both ternary additives and non-fullerene acceptors in organic photovoltaics (OPVs) as a result of their ease of synthesis, chemical stability and strong absorption. In this study, bis(3,4,5-trifluorophenoxy) silicon phthalocyanine ((345F)2-SiPc)) and bis(2,4,6-trifluorophenoxy) silicon phthalocyanine ((246F)2-SiPc)) are employed as acceptors in mixed solution/evaporation planar heterojunction (PHJ) devices. The donor layer, either poly(3-hexylthiophene) (P3HT) or poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT), was spin coated followed by the evaporation of the SiPc acceptor thin film. Several different donor/acceptor combinations were investigated in addition to investigations to determine the effect of film thickness on device performance. Finally, the effects of annealing, prior to SiPc deposition, after SiPc deposition, and during SiPc deposition were also investigated. The devices which performed the best were obtained using PCDTBT as the donor, with a 90 nm film of (345F)2-SiPc as the acceptor, followed by thermal annealing at 150 °C for 30 min of the entire mixed solution/evaporation device. An open-circuit voltage (Voc) of 0.88 V and a fill factor (FF) of 0.52 were achieved leading to devices that outperformed corresponding fullerene-based PHJ devices.
Development of Simple-To-Use Predictive Models to Determine Thermal Properties of Fe2O3/Water-Ethylene Glycol Nanofluid
Authors: Ahmadi Mohammad Hossein , Ghahremannezhad Ali , Chau Kwok-Wing , Seifaddini Parinaz , Ramezannezhad Mohammad , Ghasempour Roghayeh
Published: March 2019

Thermophysical properties of nanofluids play a key role in their heat transfer capability and can be significantly affected by several factors, such as temperature and concentration of nanoparticles. Developing practical and simple-to-use predictive models to accurately determine these properties can be advantageous when numerous dependent variables are involved in controlling the thermal behavior of nanofluids. Artificial neural networks are reliable approaches which recently have gained increasing prominence and are widely used in different applications for predicting and modeling various systems. In the present study, two novel approaches, Genetic Algorithm-Least Square Support Vector Machine (GA-LSSVM) and Particle Swarm Optimization- artificial neural networks (PSO-ANN), are applied to model the thermal conductivity and dynamic viscosity of Fe2O3/EG-water by considering concentration, temperature, and the mass ratio of EG/water as the input variables. Obtained results from the models indicate that GA-LSSVM approach is more accurate in predicting the thermophysical properties. The maximum relative deviation by applying GA-LSSVM was found to be approximately ±5% for the thermal conductivity and dynamic viscosity of the nanofluid. In addition, it was observed that the mass ratio of EG/water has the most significant impact on these properties.
A New Class of Strongly Asymmetric PKA Algorithms: SAA-5
Authors: Accardi Luigi , Iriyama Satoshi , Jimbo Koki , Regoli Massimo
Published: March 2019

A new class of public key agreement (PKA) algorithms called strongly-asymmetric algorithms (SAA) was introduced in a previous paper by some of the present authors. This class can be shown to include some of the best-known PKA algorithms, for example the Diffie–Hellman and several of its variants. In this paper, we construct a new version of the previous construction, called SAA-5, improving it in several points, as explained in the Introduction. In particular, the construction complexity is reduced, and at the same time, robustness is increased. Intuitively, the main difference between SAA-5 and the usual PKA consists of the fact that in the former class, B (Bob) has more than one public key and A (Alice) uses some of them to produce her public key and others to produce the secret shared key (SSK). This introduces an asymmetry between the sender of the message (B) and the receiver (A) and motivates the name for this class of algorithms. After describing the main steps of SAA-5, we discuss its breaking complexity assuming zero complexity of discrete logarithms and the computational complexity for both A and B to create SSK.
Liquid-Crystalline Dispersions of Double-Stranded DNA
Authors: Yevdokimov Yuri , Skuridin Sergey , Salyanov Viktor , Semenov Sergey , Kats Efim
Published: March 2019

In this review, we compare the circular dichroism (CD) spectra of liquid-crystalline dispersion (LCD) particles formed in PEG-containing aqueous-salt solutions with the purpose of determining the packing of ds DNA molecules in these particles. Depending on the osmotic pressure of the solution, the phase exclusion of ds DNA molecules at room temperature results in the formation of LCD particles with the cholesteric or the hexagonal packing of molecules. The heating of dispersion particles with the hexagonal packing of the ds DNA molecules results in a new phase transition, accompanied by an appearance of a new optically active phase of ds DNA molecules. Our results are rationalized by way of a concept of orientationally ordered “quasinematic” layers formed by ds DNA molecules, with a parallel alignment in the hexagonal structure. These layers can adopt a twisted configuration with a temperature increase; and as a result of this process, a new, helicoidal structure of dispersion particle is formed (termed as the “re-entrant” cholesteric phase). To prove the cholesteric pattern of ds DNA molecules in this phase, the “liquid-like” state of the dispersion particles was transformed into its “rigid” counterpart.
Surface-Controlled Photocatalysis and Chemical Sensing of TiO2, α-Fe2O3, and Cu2O Nanocrystals
Authors: Kusior Anna , Synowiec Milena , Zakrzewska Katarzyna , Radecka Marta
Published: March 2019

A relatively new approach to the design of photocatalytic and gas sensing materials is to use the shape-controlled nanocrystals with well-defined facets exposed to light or gas molecules. An abrupt increase in a number of papers on the synthesis and characterization of metal oxide semiconductors such as a TiO2, α-Fe2O3, Cu2O of low-dimensionality, applied to surface-controlled photocatalysis and gas sensing, has been recently observed. The aim of this paper is to review the work performed in this field of research. Here, the focus is on the mechanism and processes that affect the growth of nanocrystals, their morphological, electrical, and optical properties and finally their photocatalytic as well as gas sensing performance.
Crystal Growth of Multifunctional Borates and Related Materials
Authors: Leonyuk Nikolay I
Published: March 2019

Crystalline materials play an important role in modern physics and electronics [...]
Plasticity in Three-Dimensional Geometry of Branching Corals Along a Cross-Shelf Gradient
Authors: Doszpot Neil E. , McWilliam Michael J. , Pratchett Morgan S. , Hoey Andrew S. , Figueira Will F.
Published: March 2019

Scleractinian corals often exhibit high levels of morphological plasticity, which is potentially important in enabling individual species to occupy benthic spaces across a wide range of environmental gradients. This study tested for differences in the three-dimensional (3D) geometry of three branching corals, Acropora nasuta, Pocillopora spp. and Stylophora pistillata among inner-, mid- and outer-shelf reefs in the central Great Barrier Reef, Australia. Important attributes of coral morphology (e.g., surface area to volume ratio) were expected to vary linearly across the shelf in accordance with marked gradients in environmental conditions, but instead, we detected non-linear trends in the colony structure of A. nasuta and Pocillopora spp. The surface area to volume ratio of both A. nasuta and Pocillopora spp. was highest at mid-shelf locations, (reflecting higher colony complexity) and was significantly lower at both inner-shelf and outer-shelf reefs. The branching structure of these corals was also far more tightly packed at inner-shelf and outer-shelf reefs, compared to mid-shelf reefs. Apparent declines in complexity and inter-branch spacing at inner and outer-shelf reefs (compared to conspecifics from mid-shelf reefs) may reflect changes driven by gradients of sedimentation and hydrodynamics. The generality and explanations of observed patterns warrant further investigation, which is very feasible using the 3D-photogrammetry techniques used in this study.
Category Theory for Autonomous and Networked Dynamical Systems
Authors: Delvenne Jean-Charles
Published: March 2019

In this discussion paper we argue that category theory may play a useful role in formulating, and perhaps proving, results in ergodic theory, topogical dynamics and open systems theory (control theory). As examples, we show how to characterize Kolmogorov–Sinai, Shannon entropy and topological entropy as the unique functors to the nonnegative reals satisfying some natural conditions. We also provide a purely categorical proof of the existence of the maximal equicontinuous factor in topological dynamics. We then show how to define open systems (that can interact with their environment), interconnect them, and define control problems for them in a unified way.
Dynamics of Ebola Disease in the Framework of Different Fractional Derivatives
Authors: Muhammad Altaf Khan , Atangana Abdon
Published: March 2019

In recent years the world has witnessed the arrival of deadly infectious diseases that have taken many lives across the globe. To fight back these diseases or control their spread, mankind relies on modeling and medicine to control, cure, and predict the behavior of such problems. In the case of Ebola, we observe spread that follows a fading memory process and also shows crossover behavior. Therefore, to capture this kind of spread one needs to use differential operators that posses crossover properties and fading memory. We analyze the Ebola disease model by considering three differential operators, that is the Caputo, Caputo–Fabrizio, and the Atangana–Baleanu operators. We present brief detail and some mathematical analysis for each operator applied to the Ebola model. We present a numerical approach for the solution of each operator. Further, numerical results for each operator with various values of the fractional order parameter α are presented. A comparison of the suggested operators on the Ebola disease model in the form of graphics is presented. We show that by decreasing the value of the fractional order parameter α , the number of individuals infected by Ebola decreases efficiently and conclude that for disease elimination, the Atangana–Baleanu operator is more useful than the other two.
Using Permutations for Hierarchical Clustering of Time Series
Authors: Cánovas Jose S. , Guillamón Antonio , Ruiz-Abellón María Carmen
Published: March 2019

Two distances based on permutations are considered to measure the similarity of two time series according to their strength of dependency. The distance measures are used together with different linkages to get hierarchical clustering methods of time series by dependency. We apply these distances to both simulated theoretical and real data series. For simulated time series the distances show good clustering results, both in the case of linear and non-linear dependencies. The effect of the embedding dimension and the linkage method are also analyzed. Finally, several real data series are properly clustered using the proposed method.
Correction: Veen, D.; Stoel, D.; Schalken, N.; Mulder, K.; Van de Schoot, R. Using the Data Agreement Criterion to Rank Experts’ Beliefs. Entropy 2018, 20, 592
Authors: Veen Duco , Stoel Diederick , Schalken Naomi , Mulder Kees , van de Schoot Rens
Published: March 2019

Due to a coding error the marginal likelihoods have not been correctly calculated for the empirical example and thus the Bayes Factors following from these marginal likelihoods are incorrect. The corrections required occur in Section 3.2 and in two paragraphs of the discussion in which the results are referred to. The corrections have limited consequences for the paper and the main conclusions hold. Additionally typos in Equations, and, an error in the numbering of the Equations are remedied.
Technology-Enhanced Learning in Audiovisual Education: The Case of Radio Journalism Course Design
Authors: Matsiola Maria , Spiliopoulos Panagiotis , Kotsakis Rigas , Nicolaou Constantinos , Podara Anna
Published: March 2019

Journalism is in a state of perpetual change due to the implementation of technological tools on an everyday basis. In the contemporary news distribution environment, the boundaries between media are no longer distinct, therefore media/journalism educational institutions should adapt curricula according to the needs of each type of medium. The aim of this paper is to present the incorporated technologies in the radio journalism undergraduate course of the School of Journalism and Mass Communications at the Aristotle University of Thessaloniki and evaluate their necessity according to the students themselves. After the completion of the course, which involves the use of specialized technological tools in audio recording and editing, a survey employing quantitative method based on the technology acceptance model was conducted. The results indicate that the students, despite the difficulties that were encountered due to the initial lack of knowledge on the technology applied, evaluated very highly both their satisfaction with the produced outcome and the usefulness of the procedure. In fact, the major result is that perceived usefulness is a key factor that determines the utilization of specialized technology.
Mobile-Oriented Future Internet: Implementation and Experimentations over EU–Korea Testbed
Authors: Kim Ji-In , Choi Nak-Jung , You Tae-Wan , Jung Heeyoung , Kwon Young-Woo , Koh Seok-Joo
Published: March 2019

Today’s mobility management (MM) architectures, such as Mobile Internet Protocol (IP) and Proxy Mobile IP, feature integration of data and control planes, as well as centralized mobility control. In the existing architecture, however, the tight integration of the data and control planes can induce a non-optimal routing path, because data packets are delivered via a central mobility agent, such as Home Agent and Local Mobility Anchor. Furthermore, the centralized mobility control mechanism tends to increase traffic overhead due to the processing of both data and control packets at a central agent. To address these problems, a new Internet architecture for the future mobile network was proposed, named Mobile-Oriented Future Internet (MOFI). The MOFI architecture was mainly designed as follows: (1) separation of data and control planes for getting an optimal data path; (2) distributed identifier–locator mapping control for alleviating traffic overhead at a central agent. In this article, we investigate the validity of the MOFI architecture through implementation and experimentations over the European Union (EU)–Korea testbed network. For this purpose, the MOFI architecture is implemented using OpenFlow and Click Modular Router over a Linux platform, and then it is evaluated over the locally and internationally configured EU–Korea testbed network. In particular, we operate two realistic communication scenarios over the EU–Korea testbed network. From the experimentation results, we can see that the proposed MOFI architecture can not only provide the mobility management efficiently, but also support the backward compatibility for the current IP version 6 (IPv6) applications and an Internet Protocol network.
An Efficient Super-Resolution Network Based on Aggregated Residual Transformations
Authors: Liu Yan , Zhang Guangrui , Wang Hai , Zhao Wei , Zhang Min , Qin Hongbo
Published: March 2019

In this paper, we propose an efficient multibranch residual network for single image super-resolution. Based on the idea of aggregated transformations, the split-transform-merge strategy is exploited to implement the multibranch architecture in an easy, extensible way. By this means, both the number of parameters and the time complexity are significantly reduced. In addition, to ensure the high-performance of super-resolution reconstruction, the residual block is modified and simplified with reference to the enhanced deep super-resolution network (EDSR) model. Moreover, our developed method possesses advantages of flexibility and extendibility, which are helpful to establish a specific network according to practical demands. Experimental results on both the Diverse 2K (DIV2K) and other standard datasets show that the proposed method can achieve a good performance in comparison with EDSR under the same number of convolution layers.
Compact UV LED Lamp with Low Heat Emissions for Biological Research Applications
Authors: Pirc Matija , Caserman Simon , Ferk Polonca , Topič Marko
Published: March 2019

Much biomedical research focuses on the effects of UV light on human cells. UV light sources are a prerequisite for such research. This paper presents the design and achieved performance of a UVA (Ultraviolet A: 320–400 nm) and a UVB (Ultraviolet B: 290–320 nm) LED-based lamp suitable for use in bioassays, as well as inside an incubator. Numerical simulations were used to optimise the number, layout and output power of LEDs to achieve good irradiance homogeneity while maintaining low costs. Design was optimised for the efficient transfer of generated heat away from the irradiated samples through the heatsink at the back of the lamps. The average irradiance of the target surface by the UVA lamp was 70.1 W/m2 with a maximum deviation of 4.9%, and the average irradiance by the UVB lamp was 3.1 W/m2 with a maximum deviation of 4.8%. With the UVA and UVB lamps, the temperature of samples undergoing irradiation in the incubator rises from 37 to 42 °C within 40 and 67 min, respectively. This by far exceeds the required UV irradiation time in most cases. Tests on Jurkat and HEK-293 cell cultures confirmed the suitability of our lamps for biomedical research.
Parametric Design of a Class of Full-Band Waveguide Differential Phase Shifters
Authors: Cano Juan Luis , Mediavilla Angel , Tribak Abdelwahed
Published: March 2019

Differential phase shifters are common circuits in communication systems where a fixed phase difference between two points within the circuit is required. Among the available technologies, waveguide phase shifters are preferred for applications such as antenna feed or beam-forming networks. Typical designs in the literature are devoted to specific phase delays such as 90° or 180°, but any phase shift might be required, and therefore a design procedure resulting in mechanically-related parameter fitting equations for any arbitrary phase difference would be advantageous. This paper presents a parametric design of full-band (40% relative bandwidth) waveguide differential phase shifters, providing polynomial equations for all design parameters in order to obtain arbitrary phase shifts between standard rectangular waveguides with equal physical lengths. The phase shift is achieved through the use of a multi-step ridge section together with a single width-step in the shift line. The proposed design procedure results in differential phase shifters with 25 dB of return loss and minimal physical length for any phase shift between 0° and 180°. To validate this parametric design process, two exemplary differential phase shifters with 30° and 140° phase shifts were measured, showing very good agreement with the simulated results.
Analysis of the EU Residential Energy Consumption: Trends and Determinants
Authors: Tsemekidi Tzeiranaki Sofia , Bertoldi Paolo , Diluiso Francesca , Castellazzi Luca , Economidou Marina , Labanca Nicola , Ribeiro Serrenho Tiago , Zangheri Paolo
Published: March 2019

This article analyses the status and trends of the European Union (EU) residential energy consumption in light of the energy consumption targets set by the EU 2020 and 2030 energy and climate strategies. It assesses the energy efficiency progress from 2000 to 2016, using the official Eurostat data. In 2016, the residential energy consumption amounted to 25.71% of the EU’s final energy consumption, representing the second largest consuming sector after transport. Consumption-related data are discussed together with data on some main energy efficiency policies and energy consumption determinants, such as economic and population growth, weather conditions, and household and building characteristics. Indicators are identified to show the impact of specific determinants on energy consumption and a new indicator is proposed, drawing a closer link between energy trends and policy and technological changes in the sector. The analysis of these determinants highlights the complex dynamics behind the demand of energy in the residential sector. Decomposition analysis is carried out using the Logarithmic Mean Divisia Index technique to provide a more complete picture of the impact of various determinants (population, wealth, intensity, and weather) on the latest EU-28 residential energy consumption trends. The article provides a better understanding of the EU residential energy consumption, its drivers, the impact of current policies, and recommendations on future policies.
Applications of the 3T Method and the R1 Formula as Efficiency Assessment Tools for Comparing Waste-to-Energy and Landfilling
Authors: Vakalis Stergios , Moustakas Konstantinos
Published: March 2019

The assessment of novel waste-to-energy technologies has several drawbacks due to the nature of the R1 formula. The 3T method, which aims to cover this gap, combines thermodynamic parameters in a radar graph and the overall efficiency is calculated from the area of the trapezoid. The present study expands the application of the 3T method in order to make it suitable for utilization in other energy-from-waste technologies. In the framework of this study, a 3T specialized solution is developed for the case of landfilling plus landfill gas recovery, with the potential inclusion of landfill mining. Numerical applications have been performed for waste-to-energy and landfilling by using both the R1 formula and the 3T method. The model Land GEM was used for the calculation of the total landfill gas. The Combined Heat and Power (CHP) efficiency of the landfill gas CHP efficiency was 16.6%–33.1%, and for the waste-to-energy plant, the CHP efficiency was over 70%. The full range of parameters, like metal recovery and quality of CHP, were not fully reflected by the R1 formula, which returned values of 1.07 for waste-to-energy and from 0.37 to 0.63 for different landfilling scenarios. Contrary to that, the 3T method calculated values between 0.091 and 0.307 for the waste-to-energy plant and values between 0.011 and 0.121 for the various landfilling scenarios. The 3T method is able to account for the recovery of materials like metals and assess the quality of the output flows. The 3T method was able to successfully provide a solution for the case of landfilling plus landfill gas recovery, with the potential inclusion of landfill mining, and directly compares the results with the conventional case of waste-to-energy.
Short-Term Electricity Price Forecasting with a Composite Fundamental-Econometric Hybrid Methodology
Authors: de Marcos Rodrigo A. , Bello Antonio , Reneses Javier
Published: March 2019

Various power exchanges are nowadays being affected by a plethora of factors that, as a whole, cause considerable instabilities in the system. As a result, traders and practitioners must constantly adapt their strategies and look for support for their decision-making when operating in the market. In many cases, this calls for suitable electricity price forecasting models that can account for relevant aspects for electricity price forecasting. Consequently, fundamental-econometric hybrid approaches have been developed by many authors in the literature, although these have rarely been applied in short-term contexts, where other considerations and issues must be addressed. Therefore, this work aims to develop a robust hybrid methodology that is capable of making the most of the advantages fundamental and the hybrid model in a synergistic manner, while also providing insight as to how well these models perform across the year. Several methods have been utilised in this work in order to modify the hybridisation approach and the input datasets for enhanced predictive accuracy. The performance of this proposal has been analysed in the real case study of the Iberian power exchange and has outperformed other well-recognised and traditional methods.
Development of Nanofluids for Perdurability in Viscosity Reduction of Extra-Heavy Oils
Authors: Montes Daniel , Orozco Wendy , Taborda Esteban A. , Franco Camilo A. , Cortés Farid B.
Published: March 2019

The primary objective of this study is the development of nanofluids based on different diluent/dispersant ratios (DDR) for extra-heavy oil (EHO) viscosity reduction and its perdurability over time. Different diluents such as xylene, diesel, n-pentane, and n-heptane were evaluated for the formulation of the carrier fluid. Instability of asphaltenes was assessed for all diluents through colloidal instability index (CII) and Oliensis tests. Rheology measurements and hysteresis loop tests were performed using a rotational rheometer at 30 °C. The CII values for the alkanes type diluents were around 0.57, results that were corroborated with the Oliensis tests as asphaltenes precipitation was observed with the use of these diluents. This data was related to the viscosity reduction degree (VRD) reported for the different diluents. With the use of the alkanes, the VRD does not surpass the 60%, while with the use of xylene a VRD of approximately 85% was achieved. Dimethylformamide was used as a dispersant of the nanoparticles and had a similar VRD than that for xylene (87%). Subsequent experiments were performed varying the DDR (xylene/dimethylformamide) for different dosages up to 7 vol % determining that a DDR = 0.2 and a dosage of 5 vol % was appropriated for enhancing EHO VRD, obtaining a final value of 89%. Different SiO2 nanoparticles were evaluated in the viscosity reduction tests reporting the best results using 9 nm nanoparticles that were then included at 1000 mg·L−1 in the carrier fluid, increasing the VRD up to 4% and enhancing the perdurability based on the rheological hysteresis and the viscosity measurements for 30 days. Results showed a viscosity increase of 20 and 80% for the crude oil with the nanofluid and the carrier fluid after 30 days, respectively. The nanoparticles have a synergistic effect in the viscosity reduction and the inhibition of the viscoelastic network re-organization (perdurability) after treatment application which was also observed in the rheological modeling carried out with Cross and Carreau models as the reported characteristic relaxation time was increased almost a 20%. Moreover, the Vipulanandan rheological model denotes a higher maximum stress value reached by the EHO with the addition of nanofluids which is derived from the EHO internal structure rearrangement caused by the asphaltenes adsorption phenomenon.
Long Term Impact of Grid Level Energy Storage on Renewable Energy Penetration and Emissions in the Chilean Electric System
Authors: Maximov Serguey A. , Harrison Gareth P. , Friedrich Daniel
Published: March 2019

Chile has abundant solar and wind resources and renewable generation is becoming competitive with fossil fuel generation. However, due to renewable resource variability their large-scale integration into the electricity grid is not trivial. This study evaluates the long-term impact of grid level energy storage, specifically Pumped Thermal Energy Storage (PTES), on the penetration of solar and wind energies and on CO2 emissions reduction in Chile. A cost based linear optimization model of the Chilean electricity system is developed and used to analyse and optimize different renewable generation, transmission and energy storage scenarios until 2050. For the base scenario of decommissioning ageing coal plants and no new coal and large hydro generation, the generation gap is filled by solar photovoltaic (PV), concentrated solar power (CSP) and flexible gas generation with the associated drop of 78% in the CO2 emission factor. The integration of on-grid 8h capacity storage increases the solar PV fraction which leads to a 6% reduction in operation and investment costs by 2050. However, this does not necessarily lead to further reductions in the long term emissions. Thus, it is crucial to consider all aspects of the energy system when planning the transition to a low carbon electricity system.
Evaluation of Using Biogas to Supply the Dual Fuel Diesel Engine of an Agricultural Tractor
Authors: Owczuk Marlena , Matuszewska Anna , Kruczyński Stanisław , Kamela Wojciech
Published: March 2019

It is known that biogas without prior purification to biomethane is a commonly used fuel only for the stationary internal combustion engines but not for vehicle engines. The current study evaluates the use of biogas without its prior upgrading to biomethane as fuel for tractor engines. The following tests were carried out: biochemical methane potential tests, dynamometer engine tests, and field tests with the use of a tractor. The average methane content in biogas obtained from vegetable wastes exceeded 60%. The tests performed on the engine dynamometer showed that the engine powered by dual fuel worked stably when diesel was replaced by 40% biogas (containing 50% of CO2) or 30% methane. Dual fuel supplying of the engine caused an increase in the concentration of hydrocarbons and carbon monoxide in the exhaust gases and a decrease or no effect in the concentration of particulate matter and nitrogen oxides. It did not significantly affect the dynamics of the vehicle and its useful properties. Biogas that contains a maximum of 50% CO2 and from which H2S, moisture, and siloxanes have been largely removed, is suitable as a fuel for tractors. Such biogas can be obtained in biogas plants from different substrates, e.g., vegetable or agriculture wastes as well as biodegradable municipal wastes.
A New Method Based on Thermal Response Tests for Determining Effective Thermal Conductivity and Borehole Resistivity for Borehole Heat Exchangers
Authors: Sapińska-Sliwa Aneta , Rosen Marc A. , Gonet Andrzej , Kowalczyk Joanna , Sliwa Tomasz
Published: March 2019

Research on borehole heat exchangers is described on the development of a method for the determination, based on thermal response tests, of the effective thermal conductivity and the thermal resistivity for borehole heat exchangers. This advance is important, because underground thermal energy storage increasingly consists of systems with a large number of borehole heat exchangers, and their effective thermal conductivities and thermal resistivities are significant parameters in the performance of the system (whether it contains a single borehole or a field of boreholes). Borehole thermal energy storages provide a particularly beneficial method for using ground energy as a clean thermal energy supply. This benefit is especially relevant in cities with significant smog in winter. Here, the authors describe, in detail, the development of a formula that is a basis for the thermal response test that is derived from Fourier’s Law, utilizing a new way of describing the basic parameters of the thermal response test, i.e., the effective thermal conductivity and the thermal resistivity. The new method is based on the resistivity equation, for which a solution giving a linear regression with zero directional coefficient is found. Experimental tests were performed and analyzed in support of the theory, with an emphasis on the interpretation differences that stem from the scope of the test.
A Novel Social Spider Optimization Algorithm for Large-Scale Economic Load Dispatch Problem
Authors: Kien Le Chi , Nguyen Thang Trung , Hien Chiem Trong , Duong Minh Quan
Published: March 2019

The paper develops an improved social spider optimization algorithm (ISSO) for finding optimal solutions of economic load dispatch (ELD) problems. Different ELD problem study cases can bring huge challenges for testing the robustness and effectiveness of the proposed ISSO method since discontinuous objective functions as well as complicated constraints are taken into account. The improved method is different from original social spider optimization algorithm (SSSO) by performing several modifications directly related to three processes of new solution generation. Namely, the proposed method keeps one formula for the first and the second generations and modify them effectively while SSSO has two different formulas for each generation. In the third generation, the proposed method applies a new formula for determining the mating radius of dominant males and females with the intent to expand search space and avoid falling into local zones. The modifications can support the proposed ISSO method find better solutions with faster manner than SSSO while the number of control parameters and the number of computational processes can be reduced. As a result, the proposed method can find much less generation cost and achieve faster search speeds than SSSO for all considered systems. On the other hand, the search ability evaluation of the proposed method is also given by comparing results with other existing methods available in previous studies. The proposed method can obtain approximate or better results and faster convergence than nearly all compared methods excluding for the last system. Consequently, the proposed ISSO method can be recommended to be a strong method for ELD problem and it can be tried for other mathematical problems in engineering.
Analyzing the Impact of Energy, Export Variety, and FDI on Environmental Degradation in the Context of Environmental Kuznets Curve Hypothesis: A Case Study of India
Authors: Adamu Tijjani Musa , Haq Ihtisham ul , Shafiq Muhammad
Published: March 2019

The economic size of the Indian economy and its status as one of the major global emitters of carbon emissions makes the country a good place to study the determinants of environmental degradation in India. The study aims at analyzing the impact of energy, export variety, and foreign direct investment (FDI) on environmental degradation in India in the context of environmental Kuznets curve (EKC) hypothesis. The long run relationship was found between variables of the study through a cointegration test, whereas long run estimates were obtained through cointegration and dynamic ordinary least squares (DOLS). Results of the study reveal that energy consumption, export variety, FDI, and income positively contributed to environmental degradation in India. Results also unveil that the EKC hypothesis does not exist in India. Causality analyses document unidirectional causality from income and FDI to environmental degradation, and bidirectional causality was witnessed between energy consumption and environmental degradation and between export variety and environmental degradation in the long run. The long run and the short run causality highlight that India has to forego the short run economic growth in order to improve its environmental quality and reduce global carbon emissions; however, it will not affect its long term economic development process.
Research on Hybrid Microgrid Based on Simultaneous AC and DC Distribution Network and Its Power Router
Authors: Gai Xinnan , Wang Yali , Chen Renliang , Zou Liang
Published: March 2019

Under the dual pressure of environmental pollution and energy crisis, the global energy consumption structure reform deepens unceasingly and the concept of energy internet has developed rapidly. The widespread volatility, randomness, and uncertainty of distributed new energy generation impose new requirements on distribution systems. The zigzag transformer is used as the coupling and isolating device for simultaneous AC–DC transmission. The basic principle and structure of simultaneous AC–DC power distribution network is analyzed. The topology structure of the simultaneous AC–DC hybrid microgrid and basic operating principle of the microgrid under different operating modes are proposed for the distributed power grid technology. Combined with power electronic technology, a modular multi-interface structure of power routers applied to AC–DC hybrid microgrid and its control strategy are proposed to realize the power routing control of microgrid and ensure reliable operation control of the microgrid. By building the model of simultaneous AC–DC hybrid microgrid and its power router, the rationality and effectiveness of the power router for microgrid routing control are verified.
Recent Developments in Solar Energy-Harvesting Technologies for Building Integration and Distributed Energy Generation
Authors: Vasiliev Mikhail , Nur-E-Alam Mohammad , Alameh Kamal
Published: March 2019

We present a review of the current state of the field for a rapidly evolving group of technologies related to solar energy harvesting in built environments. In particular, we focus on recent achievements in enabling the widespread distributed generation of electric energy assisted by energy capture in semi-transparent or even optically clear glazing systems and building wall areas. Whilst concentrating on recent cutting-edge results achieved in the integration of traditional photovoltaic device types into novel concentrator-type windows and glazings, we compare the main performance characteristics reported with these using more conventional (opaque or semi-transparent) solar cell technologies. A critical overview of the current status and future application potential of multiple existing and emergent energy harvesting technologies for building integration is provided.
Photon-Mediated Thermoelectric and Heat Currents through a Resonant Quantum Wire-Cavity System
Authors: Abdullah Nzar , Marif Rawezh , Rashid Hunar
Published: March 2019

We theoretically consider a short quantum wire, which on both ends is connected to leads that have different temperatures. The quantum wire is assumed to be coupled to a cavity with a single-photon mode. We calculate the heat and thermoelectric currents in the quantum wire under the effect of the photon field. In the absence of the photon field, a plateau in the thermoelectric current is observed due to the thermal smearing at a high temperature gradient. In the presence of the resonance photon field, when the energy spacing between the lowest states of the quantum wire is approximately equal to the photon energy, a suppression in thermoelectric current and negativity in the heat current are seen due to the dressed electron-photon states. It is also found that the cavity with high photon energy has more influence on the thermoelectric current at a high temperature gradient.
Application of Discrete-Interval Moving Seasonalities to Spanish Electricity Demand Forecasting during Easter
Authors: Trull Óscar , García-Díaz J. Carlos , Troncoso Alicia
Published: March 2019

Forecasting electricity demand through time series is a tool used by transmission system operators to establish future operating conditions. The accuracy of these forecasts is essential for the precise development of activity. However, the accuracy of the forecasts is enormously subject to the calendar effect. The multiple seasonal Holt–Winters models are widely used due to the great precision and simplicity that they offer. Usually, these models relate this calendar effect to external variables that contribute to modification of their forecasts a posteriori. In this work, a new point of view is presented, where the calendar effect constitutes a built-in part of the Holt–Winters model. In particular, the proposed model incorporates discrete-interval moving seasonalities. Moreover, a clear example of the application of this methodology to situations that are difficult to treat, such as the days of Easter, is presented. The results show that the proposed model performs well, outperforming the regular Holt–Winters model and other methods such as artificial neural networks and Exponential Smoothing State Space Model with Box-Cox Transformation, ARMA Errors, Trend and Seasonal Components (TBATS) methods.
Risk Assessment for the Power Grid Dispatching Process Considering the Impact of Cyber Systems
Authors: Chen Biyun , Chen Haoying , Zhang Yiyi , Zhao Junhui , Manla Emad
Published: March 2019

Power grid dispatching is a high-risk process, and its execution depends on an available cyber system. However, the effects of cyber systems have not caught enough attention in current research on risk assessments in dispatching processes, which may cause optimistic risk results. In order to solve this problem, this paper proposes a risk assessment model that considers the impact of a cyber system on power grid dispatching processes. Firstly, a cyber-physical switchgear state model that integrates the reliability states of both cyber system functions and switchgears is proposed, based on the transition of switchgear states in the dispatching process. Then, the potential effects of each operating step on power grid states are analyzed considering the failure model of cyber-physical system (CPS) components. The risk probabilities and consequences of the power grid states are calculated to quantify the risk index. Finally, the workings and effectiveness of this model are illustrated using the IEEE Reliability Test System-1979.
Boric Acid: A High Potential Candidate for Thermochemical Energy Storage
Authors: Huber Clemens , Setoodeh Jahromy Saman , Jordan Christian , Schreiner Manfred , Harasek Michael , Werner Andreas , Winter Franz
Published: March 2019

This paper aims to describe the capability of the system boric acid–boron oxide for thermochemical energy storage. As part of the systematic research and in-depth analysis of potential solid/gas reaction systems, performed during the last years, this reaction system appears to be highly promising for the future of worldwide sustainable energy supply. The analysis of the reaction heat, by means of thermogravimetric and macroscopic investigations, not only showed a significantly higher energy density of 2.2 GJ/m3, compared to sensible- and latent energy storages, but the reaction kinetic further demonstrated the reactions’ suitability to store energy from renewable energy and waste heat sources. This paper, therefore, shows a new approach regarding the application of the boric acid–boron oxide reaction system and elaborates on the advantages and challenges for its use as energy storage.
Assessing the Energy Performance of Solar Thermal Energy for Heat Production in Urban Areas: A Case Study
Authors: Șoimoșan Teodora Melania , Moga Ligia Mihaela , Danku Gelu , Căzilă Aurica , Manea Daniela Lucia
Published: March 2019

One of the major challenges faced in the optimization process of existing heating systems is the harnessing and integration of a higher share of renewable energy. Centralized integration at the thermic source leads to high investment costs at the first investment stage, and low values of conversion, transport, and storage efficiencies, due to high levels of heat loss from large-capacity entropic systems. This research paper presents a case study on the partially decentralized integration of thermal solar fields that are used for heat production in crowded urban areas within the optimization process of the existing heating system in the city of Oradea, Romania. A deterministic method was used as the method for the calculation of heat demand, in both stationary—hourly heat demand and dynamic regimes—annual heat demand, and the simulations within the configuration and the optimization process of the hybrid heating systems were carried out. In the case study, four representative urban areas with different thermal densities were analyzed within two working scenarios, which took into account the energy performances of the buildings inside the studied areas before thermal retrofitting, and after a usual thermal retrofit.
An Experimental and Simulation Study on Optimisation of the Operation of a Distributed Power Generation System with Energy Storage—Meeting Dynamic Household Electricity Demand
Authors: Ji Jie , Xia Xin , Ni Wei , Teng Kailiang , Miao Chunqiong , Wang Yaodong , Roskilly Tony
Published: March 2019

There are few experimental reports combining hybrid energy storage and diesel engine generators as the power source of distributed power generation systems. In this article, a distributed power generation with energy storage system (DG-ES) which contains a diesel engine generator and an energy storage unit is set up and tested in the laboratory to satisfy the dynamic changing load. The hybrid energy storage system is composed of a lead-acid battery and a supercapacitor. The DG-ES supplied power to meet the domestic load demand successfully under different seasons. A simulation model of this system was also set up in MATLAB software used to guide to the experimental operation of this system. The simulation results has 2.69% and 2.35% error. The results of the experimental tests show the DG-ES can provide enough power to meet the dynamic loads of the selected house, especially at peak time in both winter and summer time. Computational simulation results show that the performance of DG-ES is improved by 3.61% in summer and 1.86% in winter when the system’s operations are optimised.
A Review of the Energy Efficiency Improvement in DC Railway Systems
Authors: Popescu Mihaela , Bitoleanu Alexandru
Published: March 2019

This study is focused on the topical issue of increasing the energy efficiency in DC railway systems, in the context of global concerns for reducing the CO2 emissions by minimizing the energy consumption and energy loss. The main achievements in this complex issue are synthesized and discussed in a comprehensive review, emphasizing the implementation and application of the existing solutions on concrete case studies. Thus, all specific subtopics related to the energy efficiency are covered, starting with power quality conditioning and continuing with the recovery of braking energy, of which a large part is lost in the classic DC-traction substations. The solutions of onboard and wayside storage systems for the braking energy are discussed and compared, and practical examples are given. Then, the achievements in transforming the existing DC-traction substations in reversible substations with capabilities of power quality improvement are systematically reviewed by illustrating the main results of recent research on this topic. They include the equipment available on the market and solutions validated through implementations on experimental models. Through the results of this extensive review, useful reference and support are provided for the research and development focused on energy efficient traction systems.