bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of euxinic holomictic conditions on prokaryotic assemblages in a marine meromictic lake
Authors: Čanković M , Žućko J , Petrić I , Marguš M , Ciglenecćki I
Published: March 2020

The water column of marine Rogoznica Lake (Croatia) is stratified throughout the year. However, on rare occasions, the lake exhibits complete mixing, primarily driven by meteorological conditions. On such occasions, anoxic, sulfide-rich bottom water mixes with the oxic surface layer, triggering both the oxidation of sulfide predominantly to colloidal sulfur and the establishment of euxinic conditions throughout the water column. We investigated prokaryotic communities during euxinic holomictic conditions. High-throughput sequencing of the 16S rRNA gene showed that these sulfur-driven communities were dominated by Planctomycetales, chemolithotrophic Epsilonbactereota (mainly Arcobacteraceae) and Gammaproteobacteria (Thioglobaceae), followed by Alpha- (Rhodobacteraceae) and Deltaproteobacteria (Desulfobulbaceae and Desulfobacteraceae). The majority of archaeal sequences belonged to Nanoarchaeota, all of which were designated as Woesearchaeia. This class has not been recorded in other meromictic lakes. Both bacterial and archaeal 16S rRNA gene abundance did not vary significantly across the vertical profile of the lake, as shown by quantitative PCR. However, hierarchical clustering showed a significant difference between the microbial assemblage structure in stratified periods and during a holomictic event. Besides the structure, this stressful event had a manifold effect on bacterial and archaeal assemblages by decreasing their diversity and abundance when compared to the usual stratified conditions.
Inferring diet, feeding behaviour and causes of mortality from prey-induced injuries in a New Zealand fur seal
Authors: Hocking DP , Marx FG , Parker WMG , Rule JP , Cleuren SGC , Mitchell AD , Hunter M , Bell JD , Fitzgerald EMG , Evans AR
Published: March 2020

New Zealand fur seals Arctocephalus forsteri are the most abundant of the 4 otariid (eared seal) species distributed across Australasia. Analyses of stomach contents, scats and regurgitates suggest a diet dominated by bony fish and squid, with cartilaginous species (e.g. sharks and rays) either absent or underrepresented because of a lack of preservable hard parts. Here we report on a subadult specimen from south-eastern Australia, which was found ashore emaciated and with numerous puncture wounds across its lips, cheeks, throat and the inside of its oral cavity. Fish spines embedded in the carcass revealed that these injuries were inflicted by chimaeras and myliobatiform rays (stingrays and relatives), which matches reports on the diet of A. forsteri from New Zealand, but not South Australia. Shaking and tearing of prey at the surface may help to avoid ingestion of the venomous spines, perhaps contributing to their absence from scats and regurgitates. Nevertheless, the number and severity of the facial stab wounds, some of which led to local necrosis, likely affected the animal’s ability to feed, and may account for its death. Despite their detrimental effects, fish spine-related injuries are difficult to spot, and may be a common, albeit cryptic, type of trauma. We therefore recommend that stranded seals be systematically examined for this potentially life-threatening pathology.
QUESTIONING AND ANSWERING: A LEARNING TECHNIQUE TO IMPROVE COMMUNICATION SKILL AND LEARNING OUTCOME IN THE ELEMENTERY SCHOLL
Authors: Asmanidar Asmanidar
Published: March 2020

Communication skills are the ability to express ideas both verbally and non-verbally. Learning outcomes are the level of acquisition of student knowledge related to the development of competencies. Both of these can be improved in the classroom by using Questioning and Answering techniques. The purpose of the study was to improve communication skills and student learning outcomes in class IV SDN 006 Langgini. The study design used a Class Action Research (PTK) design which consists of four stages: planning, action, observation and reflection. The research subjects were 29 students in class IV SDB 006 Langgini. The instrument for measuring communication skills used observation sheets while learning outcomes were assessed by providing tests. Data were analyzed descriptively quantitatively. The results showed communication skills in first cycle was 63.22 and in second cycle  amounted to 73.99 which meant an increase from first cycle to second cycle. Learning outcomes also increased by 74.21 in first cycle and 89.66 in second cycle. Thus it can be concluded that the application of techniques Questioning and Answering can improve communication skills and learning outcomes of fourth grade students of SDN 006 Langgini in semester 2019/2020.
Botanical Networking: Four Holograph Letters from Charlotte Smith to James Edward Smith
Authors: Clemit Pamela , Scott Brad
Published: March 2020

Four holograph letters from the poet and novelist Charlotte Smith (1749–1806) to the botanist James Edward Smith (no relation) have recently come to light. They are published here in full for the first time, with scholarly annotations and a brief introduction. J. E. Smith purchased Linnaeus's collections in 1784 and brought them to England, where he founded the Linnean Society of London. Charlotte Smith's letters to him, written between 1797 and 1803, provide fresh perspectives on her vocation as an author, her botanical pursuits, and her participation in the scientific networks of the English Enlightenment. She inhabited a vernacular culture, focused on locality, in which there was no division between natural science and the arts. The letters open a window on to the everyday life of an impoverished woman writer, and reveal dimensions of her personality and intellectual interests beyond what is found in her published writings.
Camellia Sinensis Leaves Hydroalcoholic Extract Improves the Alzheimer’s Disease-Like Alterations Induced by Type 2 Diabetes in Rats
Authors: ÇAM Muhammet Emin , TAŞKIN Turgut
Published: March 2020

Objective: Novel investigations have confirmed that hyperglycemia is strictly associated with the development of cognitive impairment and dementia. Sodium-dependent glucose transporter (SGLT) inhibitors, which are oral antidiabetic drugs, are currently being investigated as the medication in Alzheimer's disease (AD). In our study, Camellia sinensis (green tea), which inhibits sodium-dependent glucose transporter-1 (SGLT-1), was used in the treatment of type 2 diabetes mellitus (T2DM)-induced AD-like alterations via its antidiabetic effects.Methods: High-fat diet/streptozotocin-treated rat model was chosen to provide T2DM-induced AD-like alterations. Antidiabetic effects were evaluated with the measurement of blood glucose level (BGL), oral glucose tolerance test (OGTT), and insulin tolerance test (ITT). On the other hand, novel object recognition test (NORT), open field test (OFT), passive avoidance test (PAT), and Morris’s water maze (MWM) test were performed to investigate the anti-Alzheimer's effects of C. Sinensis.Results: C. sinensis tolerated BGL for a short time but metformin, the first medication prescribed for T2DM, tolerated BGL during the test for 120 min. C. sinensis increased the number of square crosses and the frequency of grooming activity in a similar manner to metformin in OFT. C. sinensis treatment improved exploratory behavior and memory retention components in NORT. The step-through latency decreased in HFD/STZ-treated rat model but it improved with metformin and C. sinensis treatment in PAT. According to the results obtained by the MWM test, C. sinensis treatment slightly improved learning.Conclusion: C. sinensis improved short-term memory and increased the locomotor activity in rats according to the results obtained by NORT, OFT, and PA.
Effect of dietary n-3 series fatty acids on sperm motility duration of rainbow trout (Oncorhynchus mykiss Walbaum, 1792)
Authors: ÖZER KAYA Şeyma , GÜR Seyfettin , KÖPRÜCÜ Kenan , TÜRK Gaffari , SÖNMEZ Mustafa , OZCAN Sinan
Published: March 2020

Objective: This study was performed to determine the effect of different ratios of n-3 series fatty acids added to the diets of rainbow trout(Oncorhynchus mykiss) on sperm motility duration.Methods: A total of 48 male rainbow trouts about 3 years of age were used in the study and 4 groups were formed. The one that n-3 series fattyacids were not added to the diet was used as control group. n-3 series fatty acids were added to the experimental groups diets at the ratiosof 1% (E1), 2% (E2) and 3% (E3), respectively. Semen was collected by abdominal massage. The time-dependent sperm motility change wasdetected under the microscope at x400 magnification.Results: A significant decrease was detected in the motility only at 360th hour in E3 group compared to the control group (p<0.05).Conclusion: As a result, it was concluded that feeding with diets containing different ratios of n-3 series fatty acids had no effect on the motilityof rainbow trout semen under in vitro condition.
In-vitro anticandidial efficacy of tick egg wax from Hyalomma marginatum, Rhipicephalus bursa and Dermacentor marginatus
Authors: BILGIN Nazlı , HACIOGLU Mayram , BOZKURT Cagla , ERDAL Berna , KAR Sirri
Published: March 2020

Objective: In the previous studies, the antibacterial, antifungal, and antiviral efficacy of the tick egg wax-coating of certain tick species wereexamined and some significant results were obtained. However, related researches and studied tick species are limited. There are hundredsof tick species, and it is well known that the antimicrobial efficacy of the wax is closely related to the species. The aim of this study was toinvestigate the in-vitro anticandidial efficacy of the egg waxes belonging to three tick species, which have not been studied before and havequite different biological and ecological differences.Methods: In the study, the egg waxes of the tick species, Hyalomma marginatum, Rhipicephalus bursa, and Dermacentor marginatus, wereused on Candida albicans ATCC10231, Candida parapsilosis ATCC 22019, and Candida tropicalis ATCC 750. Antimycotic susceptibility test wascarried out in accordance with the Clinical and Laboratory Standards Institute (CLSI) recommendations using the M27-A3 microdilution method.Results: It was determined that the wax of Rhipicephalus bursa has inhibitory effect on Candida tropicalis ATCC 750 in a particular concentration,and no significant effects were observed in other trials.Conclusion: Anticandidial effect obtained from the egg wax of R. bursa can be associated with some distinctive biological characteristics, and itwas concluded that the detailed studies with different tick species might yield significant results for the discovery of new generation antifungals.
A dinâmica da taxa de câmbio em países emergentes: uma perspectiva Pós-Keynesiana dos casos do Brasil e do México entre 2000 e 2017
Authors: Tellez Marins Nathalie , Magalhães Prates Daniela
Published: March 2020

Na perspectiva pós-keynesiana, a taxa de câmbio é considerada um tipo de ativo financeiro sujeito às decisões de alocação de portfólio dos agentes que atuam em um sistema monetário e financeiro internacional hierárquico e assimétrico. Baseado nesta perspectiva, este artigo realiza um estudo de caso comparativo das taxas de câmbio do Brasil e do México nos anos 2000, destacando a influência de fatores institucionais. O estudo cobre seis fases do ciclo financeiro internacional e utiliza o Método de Média Móvel Exponencial e o coeficiente de Pearson para analisar a relação entre as taxas de câmbio e os determinantes da equação keynesiana. Os resultados mostram que, embora as taxas de câmbio estudadas tenham um co-movimento semelhante, existem diferenças importantes em relação à sua volatilidade e ao impacto desses determinantes.
Oil Spill Monitoring of Shipborne Radar Image Features Using SVM and Local Adaptive Threshold
Authors: Xu Jin , Wang Haixia , Cui Can , Zhao Baigang , Li Bo
Published: March 2020

In the case of marine accidents, monitoring marine oil spills can provide an important basis for identifying liabilities and assessing the damage. Shipborne radar can ensure large-scale, real-time monitoring, in all weather, with high-resolution. It therefore has the potential for broad applications in oil spill monitoring. Considering the original gray-scale image from the shipborne radar acquired in the case of the Dalian 7.16 oil spill accident, a complete oil spill detection method is proposed. Firstly, the co-frequency interferences and speckles in the original image are eliminated by preprocessing. Secondly, the wave information is classified using a support vector machine (SVM), and the effective wave monitoring area is generated according to the gray distribution matrix. Finally, oil spills are detected by a local adaptive threshold and displayed on an electronic chart based on geographic information system (GIS). The results show that the SVM can extract the effective wave information from the original shipborne radar image, and the local adaptive threshold method has strong applicability for oil film segmentation. This method can provide a technical basis for real-time cleaning and liability determination in oil spill accidents.
Application of a Novel Wavelet Shrinkage Scheme to Partial Discharge Signal Denoising of Large Generators
Authors: Li Yanan , Li Zhaohui
Published: March 2020

Partial Discharge (PD) measurements of large generators are extremely affected and hampered by noise, making the denoising of PD signal an inevitable issue. Wavelet shrinkage is the most commonly employed method for PD signal denoising. The appropriate mother wavelet and decomposition level are critically important for the denoising performance. In consideration of the PD signal characteristics of large generators, a novel wavelet shrinkage scheme for PD signal denoising is presented. In the scheme, a scale dependent wavelet selection method is proposed; the core idea is that the optimum wavelet at each scale is selected as the one maximizing the energy ratio of coefficients beside and inside the range formed by the threshold, which correspond to the signal to be reserved and noise to be removed, respectively. In addition, taking into account the influence of mother wavelet at each scale on the decomposition level, an approach for decomposition level determination is put forward based on the energy composition after decomposition at each scale. The application results on the simulated signals with different SNR obtained by combining the various pulses and measured signal on-site show the effectiveness of the proposed scheme. Besides, the denoising results are compared with that of the existing wavelet selection methods and the proposed wavelet selection method shows an obvious advantage.
Biomass-Derived Nitrogen-Doped Porous Carbon for Highly Efficient Ambient Electro-Synthesis of NH3
Authors: Li Qinglin , Chen Xiufang , Yang Yong
Published: March 2020

In this communication, we report a biomass-derived nitrogen-doped porous carbon (named as NC-800) as an electrocatalyst for the ambient conversion of N2 to NH3. The catalyst NC-800 was prepared from naturally renewable and easily available bamboo shoots, with inherently an approximate 8 wt % of N-containing components, such as the N source, in a cost-effective and environmentally benign manner. This exhibited remarkable catalytic activity with a large NH3 yield and a Faradaic efficiency as high as 16.3 μg h−mg-1cat and 27.5%, respectively, at −0.35 V versus a reversible hydrogen electrode (RHE) in 0.1 M HCl solution at ambient conditions. More importantly, the catalyst NC-800 demonstrated excellent electrochemical selectivity and stability.
The Effect of Titanium Oxide Additions on the Phase Chemistry and Properties of Chromite-Magnesia Refractories
Authors: De Villiers Johan PR , Mulange Delphin , Garbers-Craig Andrie Mariana
Published: March 2020

The microstructure of a direct-bonded chromite-magnesia refractory brick, typically used in copper and platinum converters, was modified by adding different amounts of nano-size TiO2 to the raw material mixture. Bricks with 0, 1, 3, 5, and 7 mass% TiO2 were produced and compared in terms of spinel formation; the role of the tetravalent cation Ti4+ in the bonding phase; as well as changes in density, porosity, thermal expansion, and internal stress. This was done through a comprehensive XRD and SEM-EDS study. It was found that Ti is accommodated in the secondary spinel that has formed, where Mg in excess of unity in the tetrahedral site combines with an equal amount of Ti in the octahedral sites to maintain charge balance. The 1 mass% TiO2 brick had the lowest bulk density (but not significantly different from the original chromite-magnesia brick), the smallest difference in unit cell volumes between the primary and secondary spinels, and the lowest stress arising from the smallest difference in linear thermal expansion coefficients of the phases present. The calculated porosities correspond well with experimentally determined apparent porosity values, whereas the linear thermal expansion coefficients calculated at 1392K are similar to the values measured from 293 to 1273 K.
A Dual-Species Bose-Einstein Condensate with Attractive Interspecies Interactions
Authors: Burchianti Alessia , D’Errico Chiara , Prevedelli Marco , Salasnich Luca , Ancilotto Francesco , Modugno Michele , Minardi Francesco , Fort Chiara
Published: March 2020

We report on the production of a 41 K- 87 Rb dual-species Bose–Einstein condensate with tunable interspecies interaction and we study the mixture in the attractive regime; i.e., for negative values of the interspecies scattering length a 12 . The binary condensate is prepared in the ground state and confined in a pure optical trap. We exploit Feshbach resonances for tuning the value of a 12 . After compensating the gravitational sag between the two species with a magnetic field gradient, we drive the mixture into the attractive regime. We let the system evolve both in free space and in an optical waveguide. In both geometries, for strong attractive interactions, we observe the formation of self-bound states, recognizable as quantum droplets. Our findings prove that robust, long-lived droplet states can be realized in attractive two-species mixtures, despite the two atomic components possibly experiencing different potentials.
Information Graphs Incorporating Predictive Values of Disease Forecasts
Authors: Hughes Gareth , Reed Jennifer , McRoberts Neil
Published: March 2020

Diagrammatic formats are useful for summarizing the processes of evaluation and comparison of forecasts in plant pathology and other disciplines where decisions about interventions for the purpose of disease management are often based on a proxy risk variable. We describe a new diagrammatic format for disease forecasts with two categories of actual status and two categories of forecast. The format displays relative entropies, functions of the predictive values that characterize expected information provided by disease forecasts. The new format arises from a consideration of earlier formats with underlying information properties that were previously unexploited. The new diagrammatic format requires no additional data for calculation beyond those used for the calculation of a receiver operating characteristic (ROC) curve. While an ROC curve characterizes a forecast in terms of sensitivity and specificity, the new format described here characterizes a forecast in terms of relative entropies based on predictive values. Thus it is complementary to ROC methodology in its application to the evaluation and comparison of forecasts.
Particle Swarm Optimisation: A Historical Review Up to the Current Developments
Authors: Freitas Diogo , Lopes Luiz Guerreiro , Morgado-Dias Fernando
Published: March 2020

The Particle Swarm Optimisation (PSO) algorithm was inspired by the social and biological behaviour of bird flocks searching for food sources. In this nature-based algorithm, individuals are referred to as particles and fly through the search space seeking for the global best position that minimises (or maximises) a given problem. Today, PSO is one of the most well-known and widely used swarm intelligence algorithms and metaheuristic techniques, because of its simplicity and ability to be used in a wide range of applications. However, in-depth studies of the algorithm have led to the detection and identification of a number of problems with it, especially convergence problems and performance issues. Consequently, a myriad of variants, enhancements and extensions to the original version of the algorithm, developed and introduced in the mid-1990s, have been proposed, especially in the last two decades. In this article, a systematic literature review about those variants and improvements is made, which also covers the hybridisation and parallelisation of the algorithm and its extensions to other classes of optimisation problems, taking into consideration the most important ones. These approaches and improvements are appropriately summarised, organised and presented, in order to allow and facilitate the identification of the most appropriate PSO variant for a particular application.
Research on the Node Importance of a Weighted Network Based on the K-Order Propagation Number Algorithm
Authors: Tang Pingchuan , Song Chuancheng , Ding Weiwei , Ma Junkai , Dong Jun , Huang Liya
Published: March 2020

To describe both the global and local characteristics of a network more comprehensively, we propose the weighted K-order propagation number (WKPN) algorithm to extract the disease propagation based on the network topology to evaluate the node importance. Each node is set as the source of infection, and the total number of infected nodes is defined as the K-order propagation number after experiencing the propagation time K. The simulation of the symmetric network with bridge nodes indicated that the WKPN algorithm was more effective for evaluation of the algorithm features. A deliberate attack strategy, which indicated an attack on the network according to the node importance from high to low, was employed to evaluate the WKPN algorithm in real networks. Compared with the other methods tested, the results demonstrate the applicability and advancement that a lower number of nodes, with a higher importance calculated by the K-order propagation number algorithm, has to achieve full damage to the network structure.
LSTM-NN Yaw Control of Wind Turbines Based on Upstream Wind Information
Authors: Chen Wenting , Liu Hang , Lin Yonggang , Li Wei , Sun Yong , Zhang Di
Published: March 2020

Based on wind lidar, a novel yaw control scheme was designed that utilizes forecast wind information. The new scheme can reduce the power loss caused by the lag of accurate measurement data in the traditional yaw control strategy. A theoretical analysis of the power loss caused by the traditional wind measurement inherent error and the wind direction based traditional yaw control strategy was conducted. The yaw angle error and yaw stop/start frequency in an actual wind field were statistically analyzed, and a novel Long Short Term-Neural Network (LSTM-NN) yaw control strategy based on wind lidar information was proposed. An accurate forecast of the wind direction could reduce the power loss caused by the inherent yaw misalignment, while an accurate forecast of wind speed could increase the stop/start frequency in the medium speed section within the partial load range and reduce the frequency in the low speed section within the partial load range. Thus, the power captured could be increased by 3.5% under certain wind conditions without increasing the yaw duty. Based on a simple wind evolution model and a novel yaw control strategy, the validity of the yaw control strategy was verified in a FAST/Simulink simulation model.
Organic Carbonate Production Utilizing Crude Glycerol Derived as By-Product of Biodiesel Production: A Review
Authors: Nomanbhay Saifuddin , Ong Mei Yin , Chew Kit Wayne , Show Pau-Loke , Lam Man Kee , Chen Wei-Hsin
Published: March 2020

As a promising alternative renewable liquid fuel, biodiesel production has increased and eventually led to an increase in the production of its by-product, crude glycerol. The vast generation of glycerol has surpassed the market demand. Hence, the crude glycerol produced should be utilized effectively to increase the viability of biodiesel production. One of them is through crude glycerol upgrading, which is not economical. A good deal of attention has been dedicated to research for alternative material and chemicals derived from sustainable biomass resources. It will be more valuable if the crude glycerol is converted into glycerol derivatives, and so, increase the economic possibility of the biodiesel production. Studies showed that glycerol carbonate plays an important role, as a building block, in synthesizing the glycerol oligomers at milder conditions under microwave irradiation. This review presents a brief outline of the physio-chemical, thermodynamic, toxicological, production methods, reactivity, and application of organic carbonates derived from glycerol with a major focus on glycerol carbonate and dimethyl carbonate (DMC), as a green chemical, for application in the chemical and biotechnical field. Research gaps and further improvements have also been discussed.
Preparation and Application of Magnetic Nano-Solid Acid Catalyst Fe3O4-PDA-SO3H
Authors: Wang Honghai , Lu Yifan , Liu Hongli , Yin Yi , Liang Jun
Published: March 2020

A magnetic nano-solid acid catalyst Fe3O4-PDA-SO3H was synthetized through an efficient method, as an eco-friendly and more efficient catalyst. The obtained catalyst has uniform core-shell structure, appropriate particle size, and high acid density. Fe3O4-PDA-SO3H was applied to catalyze the esterification of levulinic acid (LA) with alcohols of different chain length to produce the levulinate esters. The catalytic effect was optimized from the aspects of catalyst dosage, reaction temperature, and acid-alcohol molar ratio. Furthermore, the response surface optimization method was used to obtain the optimal conditions. Verified under these conditions, the experimental results showed that the conversion rate of LA can reach 95.87%, which was much higher than common cationic exchange resin Amberlyst 36 and Amberlyst 46. Furthermore, the recovery and reuse of the Fe3O4-PDA-SO3H was demonstrated six times without obvious loss in the activity.
Energy Calculator for Solar Processing of Biomass with Application to Uganda
Authors: Green Toby , Miria Opio Innocent , Crook Rolf , Ross Andrew
Published: March 2020

Rural areas of developing countries often have poor energy infrastructure and so rely on a very local supply. A local energy supply in rural Uganda frequently has problems such as limited accessibility, unreliability, a high expense, harmful to health and deforestation. By carbonizing waste biomass streams, available to those in rural areas of developing countries through a solar resource, it would be possible to create stable, reliable fuels with more consistent calorific values. An energy demand calculator is reported to assess the different energy demands of various thermochemical processes that can be used to create biofuel. The energy demand calculator then relates the energy required to the area of solar collector required for an integrated system. Pyrolysis was shown to require the least amount of energy to process 1 kg of biomass when compared to steam treatment and hydrothermal carbonization (HTC). This was due to the large amount of water required for steam treatment and HTC. A resource assessment of Uganda is reported, to which the energy demand calculator has been applied. Quantitative data are presented for agricultural residues, forestry residues, animal manure and aquatic weeds found within Uganda. In application to rural areas of Uganda, a linear Fresnel HTC integration shows to be the most practical fit. Integration with a low temperature steam treatment would require more solar input for less carbonization due to the energy required to vaporize liquid water.
Causes of Oil Accumulation of Isolated Bars in Lacustrine Delta
Authors: Chen Panpan , Li Cunlei , Zhang Jinliang , Li Shengrong , Ma Guiyang , Zhao Yang
Published: March 2020

After over 20 years of development in Daqingzijiang Oilfield, isolated sand bodies under the delta front and pro-delta in the Qingshankou Formation(qn)have become important oil and gas reservoir bodies. However, the cause for large amounts of isolated bar sand bodies in the lake-basin delta sediment system has not been reported in China. This article, through core observation, reveals plenty of evidence that there storm waves once existed. Combined with paleogeography and hydrodynamic force analysis, it describes the transformation effect of waves on delta sand bodies and on the formation mechanism of bar sand bodies. Based on a study on paleogeomorphology and the statistics of sand body distribution, we consider ‘Storm waves conveying sand’ and ‘landform controlling sand’ as the cause and distribution model of the delta’s isolated bar sand body formation. We also think that the superposition of multiple bar sand bodies is the direct cause of the strong anisotropy in reservoirs and the complex relationship between oil and water in reservoirs. Most of these sand bodies have formed into lenticular lithologic hydrocarbon accumulations. On the basis of this integrated study on hydrocarbon accumulation, we set up an accumulation model of lenticular hydrocarbon accumulation involving the variables ‘Surrounded by source rocks to generate hydrocarbon’, ‘Driven by pressure difference’, ‘Migration through multi pathways’ and ‘Accumulation by filtering water’.
Planning Annual LNG Deliveries with Transshipment
Authors: Li Mingyu , Schütz Peter
Published: March 2020

The introduction of transshipment ports in the liquefied natural gas (LNG) supply chain in recent years offers additional flexibility, but also challenges to the planning of the annual delivery program. We present a new variant of the LNG-annual delivery program (ADP) planning problem by considering transshipment as well as time-dependent sailing times. We present a continuous time formulation for the LNG-ADP problem and propose a rolling horizon heuristic to solve the problem. Both the model and heuristic were used to solve a case inspired by the Yamal LNG project. The computational results show that the heuristic provides good solutions within a relatively short amount of time, especially compared to the exact solution methods. However, there is a trade-off between computational time and solution quality when designing the rolling horizon heuristic. The results also show the impact storage capacity at the transshipment port has on the total cost.
A Building Block Method for Modeling and Small-Signal Stability Analysis of the Autonomous Microgrid Operation
Authors: Banković Bojan , Filipović Filip , Mitrović Nebojša , Petronijević Milutin , Kostić Vojkan
Published: March 2020

The task of the whole microgrid state-space matrix creation is usually done in a preferred textual programming language, and it presents a complicated, time-consuming, and error-prone job for a researcher without good coding practices. To ease the modeling task, contribute to the adaptation of new microgrid structures, control algorithms, and devices, and to improve the flexibility of the model, a graphical element building block method is proposed in this paper. With the proposed approach model creation of the whole microgrid is reduced to the creation of the individual element state-space model that is linked with other elements in a logical way with a graphical connection. Elements are then grouped into meaningful wholes and encapsulated with the appropriate graphical user interface that enables easy parameter modification and model complexity change. More detailed DC/DC and DC/AC models of converters than those in the literature concerning microgrid stability are presented in this paper. Those converters are incorporated in a microgrid, whose model is created using the proposed approach in MATLAB/Simulink. The dynamic response examination of the model remains easy, just as with all Simulink models, while for the linear system analysis, a specialized toolbox is used.
Developing Process Designs for Biorefineries—Definitions, Categories, and Unit Operations
Authors: Chaturvedi Tanmay , Torres Ana I. , Stephanopoulos George , Thomsen Mette Hedegaard , Schmidt Jens Ejbye
Published: March 2020

In this review, we focus on the literature that described the various unit operations in a process design flowsheet of biorefineries. We begin by establishing the accepted definitions of a biorefinery, go on to describe how to categorize biorefineries, and finally review the literature on biorefinery process designs by listing the unit operation in each process design. Distinguishing biorefineries based on feedstock, the types of processing units, and the products emanating from the biorefinery are discussed.
Effects of Agricultural, Manufacturing, and Mineral Exports on Angola’s Economic Growth
Authors: Isaiah Zayone Titus , Henneberry Shida Rastegari , Radmehr Riza
Published: March 2020

This study investigates the effects of Angola’s agricultural, manufacturing, and mineral exports on the country’s economic growth using data from 1980 to 2017. An Autoregressive Distributed Lag (ARDL) model is employed to estimate the effect of sectoral exports on economic growth. The estimation results show that while exports from all three sectors (manufacturing, mineral, and non-mineral) have driven Angola’s economic growth in the long-run; only non-manufacturing (agricultural and mineral) exports have led its growth in the short-run. Moreover, growth in non-export GDP was driven by mineral exports in the long-run and agricultural exports in the short-run. Considering the statistically significant and positive impact of mineral exports on the Angolan GDP as well as on its non-export GDP, this study points to a lack of evidence supporting the Dutch disease phenomenon in Angola.
Transient Flow of a Horizontal Well with Multiple Fracture Wings in Coalbed Methane Reservoirs
Authors: Tian Qing , Cui Yudong , Luo Wanjing , Liu Pengcheng , Ning Bo
Published: March 2020

Horizontal wells with multi-stage fractures have been widely used to improve coalbed methane (CBM) production from coalbed methane reservoirs. The main focus of this work is to establish a new semi-analytical method in the Laplace domain and investigate the transient pressure behavior in coalbed methane reservoirs. With the new semi-analytical method, flow regimes of a multi-fractured horizontal well in coalbed methane reservoirs were identified. In addition, the sensitivities of fracture conductivity, diffusion model, storability ratio, inter-porosity flow coefficient, adsorption index, fracture spacing, fracture asymmetry, non-planar angle, and wellbore storage were studied. Results indicate that six characteristic flow regimes can be identified for multi-fractured horizontal wells in coalbed methane reservoirs, which are bilinear flow, first linear flow, desorption-diffusion flow, first pseudo-radial flow, second linear flow, and second pseudo-radial flow. Furthermore, the sensitivity analysis shows that the early flow is mainly determined by the fracture conductivity, the asymmetry factor, the non-planar angle, and the wellbore storage; while the desorption-diffusion flow regime is mainly influenced by the diffusion model, the storability ratio, the inter-porosity flow coefficient, the adsorption index, and the fracture spacing. Our work can provide a deep insight into the fluid flow mechanism of multi-fractured horizontal wells in coalbed methane reservoirs.
Study of the Miller Cycle on a Turbocharged DI Gasoline Engine Regarding Fuel Economy Improvement at Part Load
Authors: Pan Xuewei , Zhao Yinghua , Lou Diming , Fang Liang
Published: March 2020

This contribution is focused on the fuel economy improvement of the Miller cycle under part-load characteristics on a supercharged DI (Direct Injection) gasoline engine. Firstly, based on the engine bench test, the effects with the Miller cycle application under 3000 rpm were studied. The results show that the Miller cycle has different extents of improvement on pumping loss, combustion and friction loss. For low, medium and high loads, the brake thermal efficiency of the baseline engine is increased by 2.8%, 2.5% and 2.6%, respectively. Besides, the baseline variable valve timing (VVT) is optimized by the test. Subsequently, the 1D CFD (Computational Fluid Dynamics) model of the Miller cycle engine after the test optimization at the working condition of 3000 rpm and BMEP (Brake Mean Effective Pressure) = 10 bar was established, and the influence of the combined change of intake and exhaust valve timing on Miller cycle was studied by simulation. The results show that as the effect of the Miller cycle deepens, the engine’s knocking tendency decreases, so the ignition timing can be further advanced, and the economy of the engine can be improved. Compared with the brake thermal efficiency of the baseline engine, the final result after simulation optimization is increased from 34.6% to 35.6%, which is an improvement of 2.9%.
Optimal Management of the Energy Flows of Interconnected Residential Users
Authors: Manservigi Lucrezia , Cattozzo Mattia , Spina Pier Ruggero , Venturini Mauro , Bahlawan Hilal
Published: March 2020

In recent years, residential users have begun to be equipped with micro-CHP (combined heat and power) generation technologies with the aim of decreasing primary energy consumption and reducing environmental impact. In these systems, the prime mover supplies both thermal and electrical energy, and an auxiliary boiler and the national electrical grid are employed as supplementary systems. In this paper, a simulation model, which accounts for component efficiency and energy balance, was developed to replicate the interaction between the users and the energy systems in order to minimize primary energy consumption. The simulation model identified the optimal operation strategy of two residential users by investigating different energy system configurations by means of a dynamic programming algorithm. The reference scenario was compared to three different scenarios by considering independent energy systems, shared thermal and electrical energy storage and also the shared prime mover. Such a comparison allowed the identification of the most suitable energy system configuration and optimized operation strategy. The results demonstrate that the optimized operation strategy smoothes the influence of the size of thermal and electrical energy storage. Moreover, the saving of primary energy consumption can be as high as 5.1%. The analysis of the economic feasibility reveals that the investment cost of the prime mover can be as high as 4000 €/kW.
Optimum Renewable Energy Investment Planning in Terms of Current Deficit: Turkey Model
Authors: Saçık Sinem Yapar , Yokuş Nihal , Alagöz Mehmet , Yokuş Turgut
Published: March 2020

In this study, a methodology was suggested for wind and solar energy investment plans through linear optimization model for the countries with an energy-based current deficit problem. The originality of the study is that it is a renewable energy investment model based on the functioning of the balance of payments for current deficit reduction, which has not previously been encountered in the literature. While creating the model, without causing external economic imbalance, certain parameters were taken into consideration such as profit transfers for the foreign direct investments, interest payments for the domestic investments, import rates for the wind and solar energy systems, energy electric power production values, electric power load balance, electricity transmission infrastructure, CO2 emission, future electric power demand projection, and import source rates in the electric power production. It was proven that the model, for the 2019–2030 period in Turkey, not only is an opportunity for decreasing the current deficit but also ensures reaching the CO2 emission reduction target. Additionally, through the investments in wind and solar energy, it was calculated that fossil-based electric power production will decrease by 80%, and a CO2 reduction will be provided, which is equivalent of 100 million tonnes GWh natural gas. As a more general result, an optimization model was created which provides a solution for countries coping with energy-based current deficit in economic terms, energy-based air pollution in environmental terms, and renewable energy technology insufficiency.
Vehicle-to-Grid in Standard and Fast Electric Vehicle Charging: Comparison of Renewable Energy Source Utilization and Charging Costs
Authors: Falkoni Anamarija , Pfeifer Antun , Krajačić Goran
Published: March 2020

Croatia aims to achieve 10% of its energy production from the renewable energy sources in the total energy consumption in the transport sector. One of the ways to achieve this goal is by the use of electric vehicles. This work comparatively analyses the financial and social aspects of vehicle-to-grid charging in standard and fast charging mode, their impact on the renewable electricity production and the total electricity consumption regulated through variable electricity prices. Data were taken for the wider urban area of the Dubrovnik region. The assumption is that the Dubrovnik region will be self-sufficient by the year 2050 with 100% renewable electricity production and that all conventional vehicles will be replaced by electric vehicles. This work aims to show that the fast charging based on 10 min time steps offers more opportunities for flexibility and utilization of renewable generation in the energy system than the standard charging based on hourly time step. The results of this work showed the opposite, where in most of the scenarios standard charging provided better results. Replacement of the existing two tariff model in electricity prices with variable electricity prices contributes to the stability of the energy system, providing better regulation of charging and higher opportunities for renewable electricity utilization in standard and fast charging and reduction of charging costs. According to the financial aspects, fast charging is shown to be more expensive, but for the social aspects, it provides electric vehicles with more opportunities for better competition in the market.
A Novel Risk-Based Prioritization Approach for Wireless Sensor Network Deployment in Pipeline Networks
Authors: Yi Xiaojian , Hou Peng , Dong Haiping
Published: March 2020

In the face of increased spatial distribution and a limited budget, monitoring critical regions of pipeline network is looked upon as an important part of condition monitoring through wireless sensor networks. To achieve this aim, it is necessary to target critical deployed regions rather than the available deployed ones. Unfortunately, the existing approaches face grave challenges due to the vulnerability of identification to human biases and errors. Here, we have proposed a novel approach to determine the criticality of different deployed regions by ranking them based on risk. The probability of occurrence of the failure event in each deployed region is estimated by spatial statistics to measure the uncertainty of risk. The severity of risk consequence is measured for each deployed region based on the total cost caused by failure events. At the same time, hypothesis testing is used before the application of the proposed approach. By validating the availability of the proposed approach, it provides a strong credible basis and the falsifiability for the analytical conclusion. Finally, a case study is used to validate the feasibility of our approach to identify the critical regions. The results of the case study have implications for understanding the spatial heterogeneity of the occurrence of failure in a pipeline network. Meanwhile, the spatial distribution of risk uncertainty is a useful priori knowledge on how to guide the random deployment of wireless sensors, rather than adopting the simple assumption that each sensor has an equal likelihood of being deployed at any location.
Reutealis Trisperma Oil Esterification: Optimization and Kinetic Study
Authors: Lim Riky , Kim Deog-Keun , Lee Jin-Suk
Published: March 2020

Reutealis trisperma, due to its high kernel-oil yield (±50%) and long productivity (±70 years), is considered to be a promising feedstock for biodiesel production. In addition, this plant, which can thrive on marginal lands, is classified as a non-edible oil since it contains a toxin known as eleostearic acid. The present study aimed to optimize the esterification step in biodiesel production from R.trisperma oil catalyzed using sulfonic ion exchange resin Lewatit K2640. The optimization step was performed using a response surface methodology through the incorporation of a central composite design. A kinetic study was performed as well, based on the assumption of a pseudo-homogeneous second-order model. Catalyst loading was found to have the most significant impact on acid value, followed by temperature and methanol-to-oil molar ratio. The optimal conditions for the esterification step were 92 °C temperature, 5.34% catalyst loading, and 5.82:1 methanol-to-oil molar ratio. The acid value and FFA conversion of R.trisperma oil under these conditions were 2.49 mg KOH/g and 91.75%, respectively. The kinetics study revealed that the constructed model could fit the experimental data well with relatively high reliability. The activation energy required for the esterification of R.trisperma oil was 33.2 kJ/mol.
Micro-Hotspots for Conservation: An Umbrella Tree Species for the Unique Socotran Reptile Fauna
Authors: Vasconcelos Raquel , Pujol-Buxó Eudald , Llorente Gustavo A. , Saeed Ahmed , Carranza Salvador
Published: March 2020

Umbrella species are defined as species that can be rare and sensitive to human disturbance, whose protection may confer the protection of other co-occurring species. The dragon’s blood tree Dracaena cinnabari Balf.f. was already considered an umbrella species on Socotra Island (Indic Ocean, Yemen) due to its ecological importance for some native biota. We studied the reptile community living on D. cinnabari from Socotra Island. We sampled reptiles on trees across most D. cinnabari populations and applied co-occurrence and network partition analyses to check if the presence of reptiles on D. cinnabari populations was random or structured. Regardless of its patched and scarce actual distribution, we report the use of this tree as a habitat by more than half of the reptile community (12 endemic reptiles). Co-occurrence and network partition analyses demonstrate that this community is structured across the distribution of dragon’s blood trees, reflecting complex allopatric, vicariant, and biotic interaction processes. Hence, these trees act as micro-hotspots for reptiles, that is, as areas where endemic and rare species that are under threat at the landscape scale co-occur. This Socotra endemic tree is currently threatened by overgrazing, overmaturity, and climate change. Its protection and declaration as an umbrella species are expected to benefit the reptile community and to protect evolutionary processes that are partially driven by the ecological links between reptiles and this tree. To our knowledge, no tree species has been proposed as an umbrella species for island vertebrate endemics so far, highlighting the ecological uniqueness of Socotra Island.