bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of major medicinal components in the fibrous root of Epimedium brevicornu Maxim
Authors: Zaiyou Jian , Guifang Xu , Yan Zhou
Published: June 2020

The contents of main medical components in the fibrous root and medicinal materials of Epimedium brevicornu Maxim was compared. The contents of epimedin C and icariin in the fibrous root and other parts of E. brevicornu were determined with RP-HPLC. The results showed that there were high contents of medical components in the fibrous root of E. brevicornu. The content of epimedin C in E. brevicornu fibrous root was obviously higher than that of other parts. The content of icariin in E. brevicornu fibrous root was close to that in the rhizome and apparently higher than that in the stem and petiole. The contents of epimedin C and icariin in the stem (including petiole) were lowest in all parts of E. brevicornu. The fibrous root cut from rhizome when cultivate E. brevicornu should be collected and utilized as medicinal materials.
Growth regulation and off-season flowering through night breaks in Chrysanthemum morifolium Ramat cv. Anmol
Authors: Thakur Tanya , Grewal HS
Published: June 2020

The photoperiodic night interruption to schedule efficient flowering time in Chrysanthemum morifolium Ramat cv. Anmol according to demand of its flowers in the market was monitored. The influence of six night interruption treatments i.e. control, <5 second flash, 30, 60, 90 and 120 min were studied on the morphological development of Chrysanthemum morifolium Ramat cv. Anmol. The results revealed that the plant height, number of branches, leaves and root suckers per plant were positively affected with increased duration of night interruption. The flowering time was significantly delayed from mid December to end of February (two months) and number of flowers per plant increased as the duration of night interruption was increased from control to 120 min. Therefore, the night interruption durations studies were helpful to schedule the sustainable flowering time in Chrysanthemum cultivar Anmol by around two months with better plant growth.
β-amyrin as an analgesic component of the leaves of Callistemon citrinus (Curtis) Skeels: Chemical, biological and in silico studies
Authors: Ahmed Farhana , Rahman Mohammed Zakiur , Khan Mohammad Firoz , Rashid Mohammad Abdur , Rahman Mohammad Sharifur
Published: June 2020

The analgesic potential of the leaves of Callistemon citrinus was reported earlier but no active principle for this analgesia was explored. To identify the major analgesic metabolite(s), the leaves were extracted with methanol and fractionated into petroleum ether, carbon tetrachloride, chloroform and aqueous soluble fractions. Based on the thin layer chromatography, the carbon tetrachloride fraction was subjected to gel permeation chromatography and a compound (1) was isolated, which was characterized as β-amyrin. Compound (1) displayed significant peripheral analgesia (p < 0.05) on mice model at an oral dose 200 mg/kg body weight. It also showed noticeable anti-inflammatory membrane stabilizing activity. In silico docking study of β-amyrin with cyclooxygenase (COX)-2 showed a good binding affinity (–9.1 Kcal/mol). Virtual pharmacokinetics and toxicity studies explore its potentials as a lead molecule having no extreme lethality.
MOTIVASI BELAJAR MANDIRI PESERTA DIDIK PADA MATA PELAJARAN PKN SMP NEGERI 2 PULAU MAKIAN (Studi Kasus Desa Malapat Kec. Makian Barat Kabupaten Halmahera Selatan)
Authors: Rusdi Risno , Yusuf Mukhtar
Published: June 2020

The formulation of the problem in this study is how the role of the teacher in motivating students' learning in VIII grade SMP Negeri 2 Pulau Makian. The purpose of this study was to determine the role of teachers in fostering learning motivation of eighth grade students of SMP Negeri 2 Pulau Makian Regency of South Halmahera in 2015/2016. The research approach used is qualitative. The research location was SMP Negeri 2 Pulau Makian, Malapat Village, West Makian Subdistrict, South Halmahera Regency, which was held from February to April 2017. The subjects of this study were teachers and students of class VIII of SMP Negeri 2 Pulau Makian with a technique of collecting data through observation, interviews, documentation. The results of this study are then processed and analyzed qualitatively using the theories or opinions of relevant experts. Based on the results of research on the motivation of independent learning of students in Civics education in SMP Negeri 2 Pulau Makian, it was concluded that motivation for independent learning in PKn subjects was to arouse students to learn, give teachings on achievement which students reach later on and form good learning habits. The forms of motivation for independent learning include determining the atmosphere of fun teaching and learning, providing interesting learning material giving gifts to those who excel, giving punishment, to those who commit violations, and giving praise. Factors that influence the motivation of independent learning, namely the lack of attention from parents (father and mother): Parents tend to let their children take care of themselves, and the influence of friends or peers. Friends like to invite negative things, such as skipping and not going to school. Keywords: Motivation, for Independent, Learning Students, PKn Subjects
PARTISIPASI POLITIK PEMILIH PEMULA DALAM PEMILIHAN LEGISLATIF TAHUN 2014 (Studi Pada Masyarakat Adat di Kelurahan Kulaba Kecamatan Pulau Ternate)
Authors: Basahona Hamis , Muhammad Syahril
Published: June 2020

This research is a study of the political participation of new voters in the 2014 legislative elections. The study of indigenous peoples is motivated by the use of local cultural symbols namely "Jou Kasa Ngom Kage" during legislative elections which refers to the obedience, and loyalty of indigenous peoples to the Sultan. The purpose of this research is (1) to find out the attractiveness of the beginner voters to the candidates who fight, (2) to find out the forms of political participation of first-time voters among indigenous peoples and (3) to find out the obstacles that hamper voter political participation beginners in the 2014 legislative elections. This type of research is qualitative research using observation, interview and documentation techniques. The results of this study indicate that (1) political participation of beginner voters in Kulaba sub-district, Ternate Island in the 2014 legislative elections, still tended to be dominated by the strength and attractiveness of charismatic traditional leaders. (2) the form of political participation of first-time voters in Kulaba Sub-District, Ternate Island as seen from involvement of novice voters in the dissemination of the stages of legislative elections, participation in campaign activities to deliver the vision and mission of political parties as well as the delivery of the vision and mission of candidates for legislative members and their presence in voting rights during elections and"Jou kasa ngom kage" (Ternate Malay) which means Jou'ou or Sultan where the people are there, this is the language of the press (media) which is trying to be manipulated by political actors in the run-up to the elections both legislative elections and Regional head elections with destination forget support from the community in the sultanate's cultural circle not a language that was born together with the birth of the kingdom of the sultan of Ternate. (3) constraints as a barrier to the participation of political voters in determining their voting rights are still influenced by the behavior of some legislative candidates who manipulate custom symbols for their political interests. Other than that there is still a lack of education level for novice voters who do not have a mature attitude in determining their choices as citizens who are free in determining their political choices. Keywords: Political Participation, Beginner Voter, Legislative Election and Kulaba Village
Habilidades Sociales en adolescentes y Funcionalidad Familiar
Authors: Esteves Villanueva Angela Rosario , Paredes Mamani Rene Paz , Calcina Condori Carmen Rosa , Yapuchura Saico Cristóbal Rufino
Published: June 2020

La adolescencia es un periodo crítico donde las habilidades sociales juegan un papel importante en el desempeño personal de cada individuo, para lo cual la familia cumple un rol fundamental en el desarrollo y consolidación de dichas habilidades sociales. El artículo tiene como objetivo identificar la relación entre habilidades sociales en adolescentes y funcionalidad familiar. Método de investigación cuantitativo, tipo descriptivo – correlacional; con una población de 726 y muestra de 251 estudiantes de primero a quinto año de secundaria, se realizó mediante el muestreo probabilístico aleatorio estratificado. El instrumento que se utilizo es el test estructurado de habilidades sociales del Ministerio de salud y el APGAR familiar que evalúa cinco funciones básicas Adaptación, Participación, Gradiente de recurso personal, Afecto, y Recursos. Los resultados indican que existe correlación positiva entre habilidades sociales y funcionalidad familiar. En conclusión, el asertividad es la habilidad más desarrollada a diferencia de la comunicación que es donde se evidencia dificultades, por otro lado, la autoestima y la toma de decisiones son habilidades que se encuentran en nivel promedio.
The Roles of Autoimmunity and Biotoxicosis in Sick Building Syndrome as a “Starting Point” for Irreversible Dampness and Mold Hypersensitivity Syndrome
Authors: Tuuminen Tamara
Published: June 2020

Background: The terminology of “sick building syndrome” (SBS), meaning that a person may feel sick in a certain building, but when leaving the building, the symptoms will reverse, is imprecise. Many different environmental hazards may cause the feeling of sickness, such as high indoor air velocity, elevated noise, low or high humidity, vapors or dust. The Aim: To describe SBS in connection with exposure to indoor air dampness microbiota (DM). Methods: A search through Medline/Pubmed. Results and Conclusions: Chronic course of SBS may be avoided. By contrast, persistent or cumulative exposure to DM may make SBS potentially life-threatening and lead to irreversible dampness and mold hypersensitivity syndrome (DMHS). The corner feature of DMHS is acquired by dysregulation of the immune system in the direction of hypersensitivities (types I–IV) and simultaneous deprivation of immunity that manifests as increased susceptibility to infections. DMHS is a systemic low-grade inflammation and a biotoxicosis. There is already some evidence that DMHS may be linked to autoimmunity. Autoantibodies towards, e.g., myelin basic protein, myelin-associated glycoprotein, ganglioside GM1, smooth muscle cells and antinuclear autoantibodies were reported in mold-related illness. DMHS is also a mitochondropathy and endocrinopathy. The association of autoimmunity with DMHS should be confirmed through cohort studies preferably using chip-based technology.
Large Deviations for Continuous Time Random Walks
Authors: Wang Wanli , Barkai Eli , Burov Stanislav
Published: June 2020

Recently observation of random walks in complex environments like the cell and other glassy systems revealed that the spreading of particles, at its tails, follows a spatial exponential decay instead of the canonical Gaussian. We use the widely applicable continuous time random walk model and obtain the large deviation description of the propagator. Under mild conditions that the microscopic jump lengths distribution is decaying exponentially or faster i.e., Lévy like power law distributed jump lengths are excluded, and that the distribution of the waiting times is analytical for short waiting times, the spreading of particles follows an exponential decay at large distances, with a logarithmic correction. Here we show how anti-bunching of jump events reduces the effect, while bunching and intermittency enhances it. We employ exact solutions of the continuous time random walk model to test the large deviation theory.
Optimized Piston Motion for an Alpha-Type Stirling Engine
Authors: Masser Robin , Khodja Abdellah , Scheunert Mathias , Schwalbe Karsten , Fischer Andreas , Paul Raphael , Hoffmann Karl Heinz
Published: June 2020

The Stirling engine is one of the most promising devices for the recovery of waste heat. Its power output can be optimized by several means, in particular by an optimized piston motion. Here, we investigate its potential performance improvements in the presence of dissipative processes. In order to ensure the possibility of a technical implementation and the simplicity of the optimization, we restrict the possible piston movements to a parametrized class of smooth piston motions. In this theoretical study the engine model is based on endoreversible thermodynamics, which allows us to incorporate non-equilibrium heat and mass transfer as well as the friction of the piston motion. The regenerator of the Stirling engine is modeled as ideal. An investigation of the impact of the individual loss mechanisms on the resulting optimized motion is carried out for a wide range of parameter values. We find that an optimization within our restricted piston motion class leads to a power gain of about 50% on average.
Application and Validation of a Dynamic Energy Simulation Tool: A Case Study with Water Flow Glazing Envelope
Authors: Moreno Santamaria Belen , del Ama Gonzalo Fernando , Pinette Danielle , Gonzalez-Lezcano Roberto-Alonso , Lauret Aguirregabiria Benito , Hernandez Ramos Juan A.
Published: June 2020

The transparent materials used in building envelopes significantly contribute to heating and cooling loads of a building. The use of transparent materials requires to solve issues regarding heat gain, heat loss, and daylight. Water flow glazing (WFG), a disruptive technology, includes glazing as part of the Heating, Ventilation and Air Conditioning (HVAC) system. Water is transparent to visible wavelengths, but it captures most of the infrared solar radiation. As an alternative to fossil fuel-based HVAC systems, the absorbed energy can be transferred to the ground through borehole heat exchangers and dissipated as a means of free-cooling. Researchers of the Polytechnic University of Madrid have developed a software tool to calculate the energy balance while incorporating the dynamic properties of WFG. This article has studied the mathematical model of that tool and validated its ability to predict energy savings in buildings, taking spectral and thermal parameters of glazing catalogs, commercial software, and inputs from the measurements of the prototypes. The results found in this article showed that it is possible to predict the thermal behavior of WFG and the energy savings by comparing the thermal parameters of two prototypes. The energy absorbed by the water depends on the mass flow rate and the inlet and outlet temperatures.
Experimental Analysis and Optimization of an R744 Transcritical Cycle Working with a Mechanical Subcooling System
Authors: Sánchez Daniel , Catalán-Gil Jesús , Cabello Ramón , Calleja-Anta Daniel , Llopis Rodrigo , Nebot-Andrés Laura
Published: June 2020

In the last century, the refrigerant R744 (carbon dioxide) has become an environmentally friendly solution in commercial refrigeration despite its particular issues related to the low critical temperature. The use of transcritical cycles in warm and hot countries reveals the necessity of adopting different configurations and technologies to improve this specific cycle. Among these, subcooling methods are well-known techniques to enhance the cooling capacity and the Coefficient of Performance (COP) of the cycle. In this work, an R600a dedicated mechanical subcooling system has been experimentally tested in an R744 transcritical system at different operating conditions. The results have been compared with those obtained using a suction-to-liquid heat exchanger (IHX) to determine the degree of improvement of the mechanical subcooling system. Using the experimental tests, a computational model has been developed and validated to predict the optimal subcooling degree and the cubic capacity of the mechanical subcooling compressor. Finally, the model has been used to analyze the effect of using different refrigerants in the mechanical subcooling unit finding that the hydrocarbon R290 and the HFC R152a are the most suitable fluids.
Distributed Operation of Microgrids Considering Secondary Frequency Restoration Based on the Diffusion Algorithm
Authors: Hong Su-Been , Nguyen Thai-Thanh , Jeon Jinhong , Kim Hak-Man
Published: June 2020

This paper proposes a distributed control of the microgrid (MG) system based on the diffusion algorithm. Unlike the existing decentralized strategy that focuses on the economic operation of the MG system, the proposed strategy performs secondary frequency regulation in addition to the optimization of the MG system. The hierarchical control technique is employed in this study, where the primary layer is responsible for power control and the secondary layer is responsible for the frequency control and economic operation of the MG system. A tested MG system with four distributed generations (DGs) is considered. Three types of communication topologies are evaluated in this study, which are line, ring, and full topologies. The proposed controller is compared to the conventional consensus controller to show the effectiveness of the proposed diffusion controller. Simulation results show that the proposed diffusion strategy improves the convergence speed of the distributed control, resulting in the improvement of power responses and frequency quality of the MG system. The tested system is implemented in the MATLAB/Simulink environment to show the feasibility of the proposed diffusion controller.
Optimization Strategy of Electric Vehicles Charging Path Based on “Traffic-Price-Distribution” Mode
Authors: Yang Wanhao , Wang Hong , Wang Zhijie , Fu Xiaolin , Ma Pengchi , Deng Zhengchen , Yang Zihao
Published: June 2020

According to the current optimization problem of electric vehicle charging path planning, a charging path optimization strategy for electric vehicles is proposed, which is under the “traffic-price-distribution” mode. Moreover, this strategy builds an electric vehicle charging and navigation system on the basis of the road traffic network model, real-time electricity price model and distribution network model. Based on the Dijkstra shortest path algorithm and Monte Carlo time-space prediction method, it gets the optimal charging path navigation with the goal of minimizing the charging cost of electric vehicles. The simulation results in MATLAB and MATPOWER (MATLAB R2018a, MATPOWER3.1b2, PSERC, Cannell University) show that the electric vehicle charging path optimization strategy can solve the local traffic congestion problem better and improve the safety and stability of the distribution network because of the fully considering the convenience of electric vehicle charging.
Using Residential and Office Building Archetypes for Energy Efficiency Building Solutions in an Urban Scale: A China Case Study
Authors: Ding Chao , Zhou Nan
Published: June 2020

Building energy consumption accounts for 36% of the overall energy end use worldwide and is growing rapidly as developing countries continue to urbanize. Understanding the energy use at urban scale will lay the foundation for identification of energy efficiency opportunities to be deployed at speed. China has almost half of global new constructions and plays an important role in building suitability. However, an open source national building energy consumption database is not available in China. To provide data support for building energy consumptions, this paper used a simulation method to develop an urban building energy consumption database for a pilot city in Wuhan, China. First, residential, small, and large office building archetype energy models were created in EnergyPlus to represent typical building energy consumption in Wuhan. The baseline reference model simulation results were further validated using survey data from the literature. Second, stochastic simulations were conducted to consider different design parameters and occupants’ energy usage intensity scenarios, such as thermal properties of the building envelope, lighting power density, equipment power density, HVAC (heating, ventilation and air conditioning) schedule, etc. A building energy consumption database was generated for typical building archetypes. Third, data-driven regression analysis was conducted to support quick building energy consumption prediction using key high- level building information inputs. Finally, a web-based urban energy platform and an interface were developed to support further third-party application development. The research is expected to provide fast energy efficiency building design solutions for urban planning, new constructions as well as building retrofits.
Power Optimization of a Modified Closed Binary Brayton Cycle with Two Isothermal Heating Processes and Coupled to Variable-Temperature Reservoirs
Authors: Tang Chenqi , Chen Lingen , Feng Huijun , Wang Wenhua , Ge Yanlin
Published: June 2020

A modified closed binary Brayton cycle model with variable isothermal pressure drop ratios is established by using finite time thermodynamics in this paper. A topping cycle, a bottoming cycle, two isothermal heating processes and variable-temperature reservoirs are included in the new model. The topping cycle is composed of a compressor, a regular combustion chamber, a converging combustion chamber, a turbine and a precooler. The bottoming cycle is composed of a compressor, an ordinary regenerator, an isothermal regenerator, a turbine and a precooler. The heat conductance distributions among the six heat exchangers are optimized with dimensionless power output as optimization objective. The results show that the double maximum dimensionless power output increases first and then tends to be unchanged while the inlet temperature ratios of the regular combustion chamber and the converging combustion chamber increase. There also exist optimal thermal capacitance rate matchings among the working fluid and heat reservoirs, leading to the optimal maximum dimensionless power output.
Fail-Operation Control of In-Wheel Motor Drive Electric Vehicle Based on Wheel Isolation and Yaw Moment Compensation
Authors: Jin Liqiang , Zhang Zhiyang , Li Jianhua , Wang Junnian
Published: June 2020

To improve the trackability of in-wheel motor drive (IWMD) and wheel-individual steer electric vehicles (EVs) when steering actuators fail, the fail-operation control strategy was proposed to correct vehicles in a steering failure situation and avoid losing control of vehicle steering. A linear quadratic regulator (LQR) decides the additional yaw moment of the vehicle according to vehicle state errors. The tire force estimation module estimates the compensating resistance moment generated by the failed wheel according to the tire slip angle and the vertical tire force. By isolating the failed wheel, the optimal torque distribution (OTD) controller allocates the additional yaw moment and the compensating resistance moment to normal wheels to realize the fail-operation control of the IWMD vehicle. The control effect was verified through co-simulation of MATLAB/Simulink and Trucksim. Compared with the uncontrolled and direct torque allocation methods, the proposed OTD method reduces the lateral trajectory error of the vehicle by 86% and 60.5%, respectively, when failure occurs, and achieves better velocity maintaining ability, which proves the effectiveness of the proposed fail-operation control strategy.
Study on Characteristic and Energy of Argillaceous Weakly Cemented Rock under Dynamic Loading by Hopkinson Bar Experiment
Authors: Meng Lingdong , Han Lijun , Meng Qingbin , Liu Kexiang , Tian Maolin , Zhu Hexuan
Published: June 2020

To study the mechanical properties of argillaceous weakly cemented rock under dynamic loading, a sample reconstituted and graded loading scheme is firstly designed, and then the reorganization rock sample is used as the research object. Using a Hopkinson pressure bar test, the responses of an argillaceous weakly cemented rock mass under different reorganization loads and different impact velocities is studied, and changes in specimen shape after impact are also analyzed. The study found that with increased of the recombination load, the amplitude of the transmitted wave increases. With increasing impact velocity, the rate of the increase in the incident wave amplitude is much larger than that of the transmission wave amplitude. The dynamic stress–strain curve can be divided into a compaction stage, an approximate linear elastic stage, a microcrack growth stage and a strain softening stage. The larger the reorganization load is, the less obvious the compression stage of the stress–strain curve is, and the greater the elastic modulus is. The peak strength and elastic modulus increase with increasing strain rate before 500 s−1. When the reorganization load is increased, the deformation decreases, and its impact resistance increases. With increasing impact velocity, the deformation of the specimen increases.
Effect of Electrostatic Field Strength on Bioelectrochemical Nitrogen Removal from Nitrogen-Rich Wastewater
Authors: Joicy Anna , Song Young-Chae , Li Jun , Oh Sang-Eun , Jang Seong-Ho , Ahn Yongtae
Published: June 2020

The effect of electrostatic fields on the bioelectrochemical removal of ammonium and nitrite from nitrogen-rich wastewater was investigated at strengths ranging from 0.2 to 0.67 V/cm in bioelectrochemical anaerobic batch reactors. The electrostatic field enriched the bulk solution with electroactive bacteria, including ammonium oxidizing exoelectrogens (AOE) and denitritating electrotrophs (DNE). The electroactive bacteria removed ammonium and nitrite simultaneously with alkalinity consumption through biological direct interspecies electron transfer (DIET) in the bulk solution. However, the total nitrogen (ammonium and nitrite) removal rate increased from 106.1 to 166.3 mg N/g volatile suspended solids (VSS).d as the electrostatic field strength increased from 0.2 to 0.67 V/cm. In the cyclic voltammogram, the redox peaks corresponding to the activities of AOE and DNE increased as the strength of the electrostatic field increased. Based on the microbial taxonomic profiling, the dominant genera involved in the bioelectrochemical nitrogen removal were identified as Pseudomonas, Petrimonas, DQ677001_g, Thiopseudomonas, Lentimicrobium, and Porphyromonadaceae_uc. This suggests that the electrostatic field of 0.67 V/cm significantly improves the bioelectrochemical nitrogen removal by enriching the bulk solution with AOE and DNE and promoting the biological DIET between them.
An Analytical Model for Natural Convection in a Rectangular Enclosure with Differentially Heated Vertical Walls
Authors: Fichera Alberto , Marcoux Manuel , Pagano Arturo , Volpe Rosaria
Published: June 2020

This paper proposes an analytical model for natural convection in a closed rectangular enclosure filled by a fluid, with imposed heat fluxes at the vertical walls and adiabatic horizontal walls. The analytical model offers a simplified, but easy to handle, description of the temperature and velocity fields. The predicted temperature, velocity, and pressure fields are shown to be in agreement with those obtained from a reliable numerical model. The Nusselt numbers for both the analytical and numerical solutions are then calculated and compared, varying both the aspect ratio of the enclosure and the Rayleigh number. Based on the comparisons, it is possible to assess the dependence of the reliability of the analytical model on the aspect ratio of the enclosure, showing that the prediction error rapidly decreases with the increase of the enclosure slenderness.
Privacy-Functionality Trade-Off: A Privacy-Preserving Multi-Channel Smart Metering System
Authors: Zhang Xiao-Yu , Kuenzel Stefanie , Córdoba-Pachón José-Rodrigo , Watkins Chris
Published: June 2020

While smart meters can provide households with more autonomy regarding their energy consumption, they can also be a significant intrusion into the household’s privacy. There is abundant research implementing protection methods for different aspects (e.g., noise-adding and data aggregation, data down-sampling); while the private data are protected as sensitive information is hidden, some of the compulsory functions such as Time-of-use (TOU) billing or value-added services are sacrificed. Moreover, some methods, such as rechargeable batteries and homomorphic encryption, require an expensive energy storage system or central processor with high computation ability, which is unrealistic for mass roll-out. In this paper, we propose a privacy-preserving smart metering system which is a combination of existing data aggregation and data down-sampling mechanisms. The system takes an angle based on the ethical concerns about privacy and it implements a hybrid privacy-utility trade-off strategy, without sacrificing functionality. In the proposed system, the smart meter plays the role of assistant processor rather than information sender/receiver, and it enables three communication channels to transmit different temporal resolution data to protect privacy and allow freedom of choice: high frequency feed-level/substation-level data are adopted for grid operation and management purposes, low frequency household-level data are used for billing, and a privacy-preserving valued-add service channel to provide third party (TP) services. In the end of the paper, the privacy performance is evaluated to examine whether the proposed system satisfies the privacy and functionality requirements.
Numerical Study on the Effects of Imbibition on Gas Production and Shut-In Time Optimization in Woodford Shale Formation
Authors: Zhou Zhou , Wei Shiming , Lu Rong , Li Xiaopeng
Published: June 2020

In shale gas formations, imbibition is significant since the tight pore structure causes a strong capillary suction pressure. After hydraulic fracturing, imbibition during the period of shut-in affects the water recovery of flowback. Although there have been many studies investigating imbibition in shale formations, few papers have studied the relationship between gas production and shut-in time under the influence of imbibition. This paper developed a numerical model to investigate the effect of imbibition on gas production to optimize the shut-in time after hydraulic fracturing. This numerical model is a 2-D two-phase (gas and water) imbibition model for simulating an imbibed fluid flow and its effect on permeability, flowback, and water recovery. The experimental and field data from the Woodford shale formation were matched by the model to properly configure and calibrate the model parameters. The experimental data consisted of the relationship between the imbibed fluid volume and permeability change, the relative permeability, and the capillary pressure for the Woodford shale samples. The Woodford field data included the gas production and flowback volume. The modeling results indicate that imbibition can be a beneficial factor for gas production, since it can increase rock permeability. However, the gas production would be reduced when excessive fluid is imbibed by the shale matrix. Therefore, the shut-in time after hydraulic fracturing, when the imbibition happens in shale, could be optimized to maximize the gas production.
Streaming Electrification Phenomenon of Electrical Insulating Oils for Power Transformers
Authors: Zdanowski Maciej
Published: June 2020

The subject matter of this study was the problem of the ECT (electrostatic charging tendency) of mineral insulation oils during their flow. The electrostatic charges generated may lead to partial discharges, and as a consequence, to the breakdown of a power transformer insulation system. In this study, the results of the ECT of mineral oils used in transformers were compared. The method of streaming electrification of insulation liquids using a flow-through system was used. The influence of flow speed, temperature, and the pipe material on the values of the electrification current and volume charge density qw were analyzed. The results obtained in this study should be taken into account regarding the operation of power transformers.
Optimal Configuration of a Gas Expansion Process in a Piston-Type Cylinder with Generalized Convective Heat Transfer Law
Authors: Chen Lingen , Ma Kang , Feng Huijun , Ge Yanlin
Published: June 2020

Optimal configurations for the working fluid expansion process in a piston-type cylinder with maximum work production are studied by applying finite time thermodynamics. The problem is solved by utilizing the modified Lagrangian. The initial and final volumes, initial internal energy and total time are fixed, and the heat transfer between the working fluid and the external heat bath obeys the generalized convective heat transfer law, which can be transformed into Newton’s heat transfer law, the Dulong–Petit heat transfer law and the square convective heat transfer law. The optimal configurations of the expansion process under three different conditions of heat transfer law are provided and compared, respectively. The results show that the heat transfer law has both quantitative and qualitative influences on the optimal configurations of the expansion process.
On the Hybridization of Microcars with Hybrid UltraCapacitors and Li-Ion Batteries Storage Systems
Authors: Ortenzi Fernando , Andrenacci Natascia , Pasquali Manlio , Villante Carlo
Published: June 2020

The objective proposed by the EU to drastically reduce vehicular CO2 emission for the years up to 2030 requires an increase of propulsion systems’ efficiency, and accordingly, the improvement their technology. Hybrid electric vehicles could have a chance of achieving this, by recovering energy during braking phases, running in pure electric mode and allowing the internal combustion engine to operate under better efficiency conditions, while maintaining traditionally expected vehicle performances (mileage, weight, available on-board volume, etc.). The energy storage systems for hybrid electric vehicles (HEVs) have different requirements than those designed for Battery Electric Vehicles (BEVs); high specific power is normally the most critical issue. Using Li-ion Batteries (LiBs) in the designing of on-board Energy Storage Systems (ESS) based only on power specifications gives an ESS with an energy capacity which is sufficient for vehicle requirements. The highest specific power LiBs are therefore chosen among those technologically available. All this leads to an ESS design that is strongly stressed over time, because current output is very high and very rapidly varies, during both traction and regeneration phases. The resulting efficiency of the ESS is correspondingly lowered, and LiBs lifetime can be relevantly affected. Such a problem can be overcome by adopting hybrid storage systems, coupling LiBs and UltraCapacitors (UCs); by properly dimensioning and controlling the ESS’ components, in fact, the current output of the batteries can be reduced and smoothed, using UCs during transients. In this paper, a simulation model, calibrated and validated on an engine testbed, has been used to evaluate the performances of a hybrid storage HEV microcar under different operative conditions (driving cycles, environment temperature and ESS State of Charge). Results show that the hybridization of the powertrain may reduce fuel consumption by up to 27%, while LiBs lifetime may be more than doubled.
Determination of the Energy Performance of a Solar Low Energy House with Regard to Aspects of Energy Efficiency and Smartness of the House
Authors: Chwieduk Dorota , Chwieduk Michał
Published: June 2020

The paper shows how difficult it is to prove technically that a building really is both low energy and smart, and that all aspects of energy efficiency have been treated equally. Regulations connected to the determination of the energy performance of residential buildings take into account only space and hot water heating energy consumption and define the indices of maximal primary energy consumption, but not energy needs based on the architecture of the building. A single family house designed and constructed as a low energy solar house in Warsaw’s suburbs is considered. Availability of solar energy and its influence on the architecture of the house is analyzed. A specific solar passive architectural concept with solar southern and cold northern buffer spaces incorporated into the interior of the house is presented. Parameters of the building’s structure, construction materials, as well as operation parameters of equipment and heating systems based on active use of solar energy, ground energy (via a heat pump) and waste heat from a ventilation system are described. Results of calculations give values of final and primary energy consumption index levels of 11.58 kWh/m2 and 25.77 kWh/m2, respectively. However, the official methodology for determination of energy performance does not allow for presenting how energy efficient and smart the building really is.
Energetic Retrofit Strategies for Traditional Sicilian Wine Cellars: A Case Study
Authors: Nocera Francesco , Caponetto Rosa , Giuffrida Giada , Detommaso Maurizio
Published: June 2020

Sicily is characterized by rural buildings, Palmenti, destined to wine production, which are scattered along the countryside and part of the local historical heritage. There are different types of rural buildings, but all have in common the use of ancient and well-established bioclimatic techniques for wine conservation and aging. Most of them were built with the double function of living space for the owner and productive spaces for all the activities correlated to the cultivations. Indeed, many rural houses, destined to the wine production, are characterized by wineries and wine cellars (the first for the wine production, the second to store the wine for the aging process). The growing production of high-quality Sicilian wines, very appreciated all over the world, leads to upgrade the ancient Palmenti to seek optimal hygrothermal conditions and, therefore, to guarantee high performance of the produced and stored wines. The purpose of this study is to investigate how the retrofit measures taken to comply with the energy regulations could affect the thermal behavior of a wine cellar constructed with consolidated bioclimatic technics. The results show the importance of not insulating the solid ground floor for maintaining suitable temperatures for the fermentation and aging of wine. This study can be useful for future analysis when comparing the optimal hygrothermal conditions of wine cellars located in homogeneous viticultural areas (with same climate, geology, soil, physical features, and height) in other parts of the world.
Hydrodynamic Effects of Tidal-Stream Power Extraction for Varying Turbine Operating Conditions
Authors: Flores Mateos Lilia , Hartnett Michael
Published: June 2020

Realistic evaluation of tidal-stream power extraction effects on local hydrodynamics requires the inclusion of the turbine’s operating conditions (TOC). An alternative approach for simulating the turbine’s array energy capture at a regional scale, momentum sink-TOC, is used to assess the impact of power extraction. The method computes a non-constant thrust force calculated based on the turbine’s operating conditions, and it uses the wake induction factor and blockage ratio to characterise the performance of a turbine. Additionally, the momentum sink-TOC relates the changes produced by power extraction, on the velocity and sea surface within the turbine’s near-field extension, to the turbine’s thrust force. The method was implemented in two hydrodynamic models that solved gradually varying flows (GVF) and rapidly varying flows (RVF). The local hydrodynamic effects produced by tidal-stream power extraction for varying the turbine’s operating conditions was investigated in (i) the thrust and power coefficient calculation, (ii) flow rate reduction, and (iii) tidal currents’ velocity and elevation profiles. Finally, for a turbine array that operates at optimal conditions, the potential energy resource was assessed. The maximisation of power extraction for electrical generation requires the use of an optimum turbine wake induction factor and an adequate blockage ratio, so that the power loss due to turbine wake mixing is reduced. On the other hand, the situations where limiting values of these parameters are used should be avoided as they lead to negligible power available. In terms of hydrodynamical models, an RVF solver provided a more accurate evaluation of the turbine’s operating conditions effect on local hydrodynamics. Particularly satisfactory results were obtained for a partial-fence. In the case of a fence configuration, the GVF solver was found to be a computationally economical tool to pre-assess the resource; however, caution should be taken as the solver did not accurately approximate the velocity decrease produced by energy extraction.
Influence of Different Structure and Specification Parameters on the Propagation Characteristics of Optical Signals Generated by GIL Partial Discharge
Authors: Chen Xiaoxin , Li Chen , Chen Liangjin , Wang Hui , Zang Yiming , Yao Weijia
Published: June 2020

Partial discharge (PD) leads to the generation of electrical, acoustic, optical, and thermal signals. The propagation characteristics of optical signals in gas insulated metal-enclosed transmission lines (GIL) are the basis of optical detection research. This paper simulates the propagation of PD optical signals in GIL through modeling GIL with different structures and specification parameters. By analyzing the optical parameters on the probe surface and the detection points when the PD source position is different, the influence of the difference in specifications caused by the voltage level on the propagation of the GIL PD optical signal is studied. The results show that the GIL cavity structure will affect the faculae distribution and the relative irradiance (RI) of the detection surface; the PD source position has a huge impact on the faculae distribution on the detection surface, but has little influence on the RI; as the voltage rises, the faculae distribution on the detection surface becomes more obvious, and the mean of RI decreases. The above results have the reference value for the manufacture of GIL equipment and the research of PD optical detection. When the specular reflection coefficient of surface material is smaller and the diffuse reflection coefficient is larger, the outline of the light spot is clearer, the proportion of brighter parts is larger, and the maximum value of the RI is larger.
Assessing the Environmental Performance of Palm Oil Biodiesel Production in Indonesia: A Life Cycle Assessment Approach
Authors: Wahyono Yoyon , Hadiyanto Hadiyanto , Budihardjo Mochamad Arief , Adiansyah Joni Safaat
Published: June 2020

The production of palm oil biodiesel in Indonesia has the potential to negatively impact the environment if not managed properly. Therefore, we conducted a life cycle assessment (LCA) study on the production of palm oil biodiesel to assess the environmental performance in Indonesia. Using an LCA approach, we analyzed the environmental indicators, including the carbon footprint, as well as the harm to human health, ecosystem diversity, and resource availability in palm oil biodiesel production. The functional unit in this study was 1 ton of biodiesel. The life cycle of palm oil biodiesel production consists of three processing units, namely the oil palm plantation, palm oil production, and biodiesel production. The processing unit with the greatest impact on the environment was found to be the oil palm plantation. The environmental benefits, namely the use of phosphate, contributed 62.30% of the 73.40% environmental benefit of the CO2 uptake from the oil palm plantation processing unit. The total human health damage of the life cycle of palm oil biodiesel production was 0.00563 DALY, while the total ecosystem’s diversity damage was 2.69 × 10−5 species·yr. Finally, we concluded that the oil palm plantation processing unit was the primary contributor of the carbon footprint, human health damage, and ecosystem diversity damage, while the biodiesel production processing unit demonstrated the highest damage to resource availability.
Hydrodynamic Analysis of Surge-Type Wave Energy Devices in Variable Bathymetry by Means of BEM
Authors: Magkouris Alexandros , Bonovas Markos , Belibassakis Kostas
Published: June 2020

A variety of devices and concepts have been proposed and thoroughly investigated for the exploitation of renewable wave energy. Many of the devices operate in nearshore and coastal regions, and thus, variable bathymetry could have significant effects on their performance. In particular, Oscillating Wave Surge Converters (OWSCs) exploit the horizontal motion of water waves interacting with the flap of the device. In this work, a Boundary Element Method (BEM) is developed, and applied to the investigation of variable bathymetry effects on the performance of a simplified 2D model of a surge-type wave energy converter excited by harmonic incident waves. Numerical results, illustrating the effects of depth variation in conjunction with other parameters, like inertia and power-take-off, on the performance of the device, are presented. Finally, a comparative evaluation of the present simplified surge-type WEC model and point absorbers is presented for a case study in a selected coastal site on the Greek nearshore area, characterized by relatively increased wave energy potential.
Mapping the Recovery Process of Vegetation Growth in the Copper Basin, Tennessee Using Remote Sensing Technology
Authors: Blanton Richard , Hossain A.K.M. Azad
Published: June 2020

The Copper Basin (CB) of southeastern Tennessee, known as the Ducktown Mining District, is a classic example of forest and soil destruction due to extensive mining and smelting operations from the mid-1800s until 1987. The smelting operation released a sulfur dioxide by-product that formed sulfuric acid precipitation which, in combination with heavy logging, led to the complete denudation of all vegetation covering 130 km2 in CB. The area has since been successfully revegetated. This study used remote sensing technology to map the different episodes of this vegetation recovery process. A time series of Landsat imagery acquired from 1977 through 2017 at 10-year intervals was used to map and analyze the changes in vegetation cover in CB. These maps were used to generate a single thematic map indicating in which 10-year period each parcel of land was revegetated. Analysis shows that the extent of non-vegetated areas continuously decreased from about 38.5 to 2.5 km2 between 1977 and 2017. The greatest increase in vegetation regrowth occurred between 1987 and 1997, which was the period when all mining and smelting activities ceased. This research could be very useful to better understand the recovery process of areas affected by mining and smelting processes.