bluuebunny/crossref_metadata_2025 huggingface dataset:
Distributed Bragg Reflectors for GaN-Based Vertical-Cavity Surface-Emitting Lasers
Authors: Zhang Cheng , ElAfandy Rami , Han Jung
Published: April 2019

A distributed Bragg reflector (DBR) is a key building block in the formation of semiconductor microcavities and vertical cavity surface emitting lasers (VCSELs). The success in epitaxial GaAs DBR mirrors paved the way for the ubiquitous deployment of III-V VCSELs in communication and mobile applications. However, a similar development of GaN-based blue VCSELs has been hindered by challenges in preparing DBRs that are mass producible. In this article, we provide a review of the history and current status of forming DBRs for GaN VCSELs. In general, the preparation of DBRs requires an optimization of epitaxy/fabrication processes, together with trading off parameters in optical, electrical, and thermal properties. The effort of epitaxial DBRs commenced in the 1990s and has evolved from using AlGaN, AlN, to using lattice-matched AlInN with GaN for DBRs. In parallel, dielectric DBRs have been studied since 2000 and have gone through a few design variations including epitaxial lateral overgrowth (ELO) and vertical external cavity surface emitting lasers (VECSEL). A recent trend is the use of selective etching to incorporate airgap or nanoporous GaN as low-index media in an epitaxial GaN DBR structure. The nanoporous GaN DBR represents an offshoot from the traditional epitaxial approach and may provide the needed flexibility in forming manufacturable GaN VCSELs. The trade-offs and limitations of each approach are also presented.
Acoustic Emission Characteristics of Graded Loading Intact and Holey Rock Samples during the Damage and Failure Process
Authors: Liu Xiaofei , Zhang Huajie , Wang Xiaoran , Zhang Chong , Xie Hui , Yang Shuai , Lu Weikai
Published: April 2019

Rock burst is the result of the development and extension of micro-cracks during the loading process of large-scale rock mass in underground space engineering. Dynamic monitoring results by acoustic emission (AE) can accurately perceive the inner fracture evolution of rock mass and effectively warn about its induced disasters early. By contrastive testing the AE parameters in the whole fracture process of the intact and holey rock samples under graded loading, their spatiotemporal evolution rules were analyzed in this paper, and the damage model of rock samples based on AE localization events was established to analyze the relationship between rock damage and loads. The results show that: (1) Under the condition of grading loading, AE parameter increases with the increase of axial stress and show three states, respectively, which are slow-growth, stabilization and rapid increasing; meanwhile, the damage of the sample has a cumulative effect with time. (2) The AE counts and energy are highly correlated with the fracture of the sample that the more severe the damage of the sample, the faster the crack propagation as well as the higher the acoustic emission counts and the energy amplitude. The damage state of granite sample can be accurately judged by two parameters to character the damage evolution process and fracture mechanism. (3) Compared with the intact rock sample, due to the pressure relief effect of the hole, the rock sample containing the hole takes a long time in the compaction stage and with higher load stress level. Although the AE counts and energy were lower in the damage process, the general law of their response during damage and instability process still exists.
Thermo-Mechanical Investigations of Packed Beds for High Temperature Heat Storage: Uniaxial Compression Test Experiments and Particle Discrete Simulations
Authors: Knödler Philipp
Published: April 2019

Thermal energy storage (TES) systems are central elements for various types of new power plant concepts and industrial processes. Depending on the specific application, energy storage systems based on sensible heat transfer with packed beds as storage inventory are a promising storage technology. Due to thermal expansion and shrinking of the packed bed’s particles during cyclic thermal charging and discharging, high technical risks arise and possibly lead to material failure. In order to accurately design the TES, suitable tools for calculating thermo-mechanical induced forces and stresses are mandatory. For this purpose, different model approaches and tools are available. Continuum models offer time-efficient simulation results but need proper parametrization, which usually requires extensive experimental effort. This paper focuses on laying the groundwork on how to facilitate the effort for the parametrization of a continuum model by deploying a discrete particle model in order to simulate soil mechanical experiments. In this context, a specifically designed test rig is introduced, which is applied for the validation of the discrete particle model.
“The Man of the Hour”: Hawthorn(e), Nebraska and Haunting
Authors: Gilloch Graeme
Published: April 2019

This paper provides a close reading and critical unfolding of central themes and motifs in Alexander Payne’s acclaimed 2013 comic ‘road movie’ Nebraska. It focuses on three key issues: (1) the symbolic significance of hawthorn as a threshold between different worlds (Hawthorne, Nebraska being the former hometown to which father and son make a detour); (2) the notion of ‘haunting’ in relation both to ‘importuning’ memories besetting the central characters and to particular sites of remembrance to which they return; and, (3) how the film’s pervasive mood of melancholy is subject to repeated interruption and punctuation by comic utterances and put-downs. In presenting us with a reluctant ‘gathering of ghosts’, a veritable phantasmagoria, the film articulates a particular sense of nostalgia, of a ‘homesickness’ understood here not in the conventional meaning of a longing to return to a forsaken ‘home’, but rather as a weariness and wariness at the prospect of revisiting familiar haunts and reviving old spirits.
Acacia Holosericea: An Invasive Species for Bio-char, Bio-oil, and Biogas Production
Authors: Reza Md Sumon , Ahmed Ashfaq , Caesarendra Wahyu , Abu Bakar Muhammad S. , Shams Shahriar , Saidur R. , Aslfattahi Navid , Azad Abul K.
Published: April 2019

To evaluate the possibilities for biofuel and bioenergy production Acacia Holosericea, which is an invasive plant available in Brunei Darussalam, was investigated. Proximate analysis of Acacia Holosericea shows that the moisture content, volatile matters, fixed carbon, and ash contents were 9.56%, 65.12%, 21.21%, and 3.91%, respectively. Ultimate analysis shows carbon, hydrogen, and nitrogen as 44.03%, 5.67%, and 0.25%, respectively. The thermogravimetric analysis (TGA) results have shown that maximum weight loss occurred for this biomass at 357 °C for pyrolysis and 287 °C for combustion conditions. Low moisture content (<10%), high hydrogen content, and higher heating value (about 18.13 MJ/kg) makes this species a potential biomass. The production of bio-char, bio-oil, and biogas from Acacia Holosericea was found 34.45%, 32.56%, 33.09% for 500 °C with a heating rate 5 °C/min and 25.81%, 37.61%, 36.58% with a heating rate 10 °C/min, respectively, in this research. From Fourier transform infrared (FTIR) spectroscopy it was shown that a strong C–H, C–O, and C=C bond exists in the bio-char of the sample.
A Generalized Adaptive Framework (GAF) for Automating Code Compliance Checking
Authors: Nawari Nawari O.
Published: April 2019

Building design review is the procedure of checking a design against codes and standard provisions to satisfy the accuracy of the design and identify non-compliances before construction begins. The current approaches for conducting the design review process in an automatic or semi-automatic manner are either based on proprietary, domain-specific or hard-coded rule-based mechanisms. These methods may be effective in their specific applications, but they have the downsides of being costly to maintain, inflexible to modify, and lack a generalized framework of rules and regulations modeling that can adapt to various engineering design realms, and thus don’t support a neutral data standard. They are often referred to as ‘Black Box’ or ‘Gray Box’ approaches. This research offers a new comprehensive framework that reduces the limitations of the cited methods. Building regulations, for instance, are legal documents transcribed and approved by professionals to be interpreted and applied by people. They are hardly as precise as formal logic. Engineers, architects, and contractors can read those technical documents and transform them into scientific notations and software applications. They can extract any data they need, reason about it, and apply it at various phases of the project. How these extraction and use are carried out is a critical component of automating the design review process. The chief goal is to address this issue by developing a Generalized Adaptive Framework (GAF) for a neutral data standard (Industry Foundation Classes (IFC)) that enables automating the code compliance checking processes to achieve design efficiency and cost-effectiveness. The objectives of this study comprise i) to develop a theoretical background to an adaptive framework that supports a neutral data standard for transforming the written code regulations and rules into a computable model, and ii) to define the various modules required for computerizing of the code compliance verification process.
Passive Ambient Comfort and Correlation of Strategies and Vernacular Devices for Habitat Design in Arid Zones: The Case of Biskra, Algeria
Authors: Berghout Belkacem , Forgues Daniel
Published: April 2019

Current concerns focus on the need to reduce energy consumption in construction and over the lifespan of buildings. A major objective is to create affordable housing. However, reducing the energy needs of the present without harming the needs of future generations remains difficult to put into practice, especially at the level of habitats in arid zones. In this research, a housing design assistance process for building designers is proposed, with the aim of converging towards a global optimum for the correlation and integration of vernacular devices and strategies in an optimized way. This will allow the integration of energy performance indicators and user comfort, in order to ultimately optimize, for this case study, the morphogenesis of residential buildings based on the morphological structure of a proposed building in Biskra, Algeria. This last developed process is articulated on various combinations distinguished for the case of the integration of devices and strategies, which allow maximum energy saving while ensuring the comfort of the occupants. As part of this research, this integration constituted a major challenge and made it possible to achieve a reduction in energy ratio of up to 25.11% compared to the standard building and the objectives of the research.
MiR-34b-5p Mediates the Proliferation and Differentiation of Myoblasts by Targeting IGFBP2
Authors: Wang Zhijun , Zhang Xiaocui , Li Zhenhui , Abdalla Bahareldin Ali , Chen Yangfeng , Nie Qinghua
Published: April 2019

As key post-transcriptional regulators, microRNAs (miRNAs) play an indispensable role in skeletal muscle development. Our previous study suggested that miR-34b-5p and IGFBP2 could have a potential role in skeletal muscle growth. Our goal in this study is to explore the function and regulatory mechanism of miR-34b-5p and IGFBP2 in myogenesis. In this study, the dual-luciferase reporter assay and Western blot analysis showed that IGFBP2 is a direct target of miR-34b-5p. Flow cytometric analysis and EdU assay showed that miR-34b-5p could repress the cell cycle progression of myoblasts, and miR-34b-5p could promote the formation of myotubes by promoting the expression of MyHC. On the contrary, the overexpression of IGFBP2 significantly facilitated the proliferation of myoblasts and hampered the formation of myotubes. Together, our results indicate that miR-34b-5p could mediate the proliferation and differentiation of myoblasts by targeting IGFBP2.
Spatial and Temporal Variation in Fecundity of Acropora spp. in the Northern Great Barrier Reef
Authors: Pratchett Morgan S. , Hoey Andrew S. , Tan Chun-Hong , Kuo Chao-Yang , Bauman Andrew G. , Kumaraswamy Rajani , Baird Andrew H.
Published: April 2019

The amount of energy invested in sexual reproduction by scleractinian corals depends on their life history strategies (i.e., allocation of energy between growth, reproduction, and maintenance). However, energy allocated to reproduction will also be affected by the amount of energy acquired and prevailing environmental conditions. Coral fecundity is therefore likely to vary spatially, especially along marked gradients in environmental conditions. One of the foremost gradients in reef structure and environmental conditions occurs with distance from the coast, whereby inner-shelf or near shore reefs are generally subject to higher levels of nutrients, sediments and pollutants, which often adversely affect reef-building corals. This study quantified fecundity (oocytes per polyp) for three species, Acropora nasuta, A. spathulata, and A. hyacinthus, at six locations in the northern Great Barrier Reef (GBR), encompassing inner-, mid- and outer-shelf reefs. Replicate colonies were sampled at each location prior to the predicted date of spawning in 2013 and 2014. Both shelf position and year were important factors explaining variation in fecundity for each of the three coral species. Most notably, there were clear and consistent declines in the number of oocytes between 2013 and 2014, coinciding with the incidence of category 4 Cylone Ita in early 2014. Contrary to expectations, polyp-level fecundity was no lower (and in some cases substantially higher) on inner-shelf reefs, compared to conspecifics growing on mid-shelf or outer-shelf reefs. The observed patterns are much more complicated than anticipated, necessitating further research to understand differential population dynamics of corals on inner-shelf versus mid- and outer-shelf reefs.
Differences in Bacterial Diversity, Composition and Function due to Long-Term Agriculture in Soils in the Eastern Free State of South Africa
Authors: Dube Joel P. , Valverde Angel , Steyn Joachim M. , Cowan Don A. , van der Waals Jacqueline E.
Published: April 2019

Land-use change from natural to managed agricultural ecosystems significantly impacts soil bacterial diversity and function. The Eastern Free State (EFS) is one of the most productive agricultural regions in South Africa. However, no studies aiming to understand the changes in bacterial diversity, composition and function due to land-use change in this area have been conducted. This study investigated, using high-throughput 16S rRNA gene amplicon sequencing, the effects of long-term agriculture on bacterial diversity, composition and putative function in the EFS by comparing microbiomes from lands that have been under agronomic activity for over 50 years to those from uncultivated land. Results indicate that agriculture increased bacterial diversity. Soil chemical analysis showed that land-use shifted soils from being oligotrophic to copiotrophic, which changed bacterial communities from being Actinobacteria dominated to Proteobacteria dominated. Predictive functional analysis using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) suggested that agricultural soil was abundant in genes associated with plant fitness and plant growth promotion, while non-agricultural soil was abundant in genes related to organic matter degradation. Together, these results suggest that edaphic factors induced by long-term agriculture resulted in shifts in bacterial diversity and putative function in the EFS.
Reef Rover: A Low-Cost Small Autonomous Unmanned Surface Vehicle (USV) for Mapping and Monitoring Coral Reefs
Authors: Raber George T. , Schill Steven R.
Published: April 2019

In the effort to design a more repeatable and consistent platform to collect data for Structure from Motion (SfM) monitoring of coral reefs and other benthic habitats, we explore the use of recent advances in open source Global Positioning System (GPS)-guided drone technology to design and test a low-cost and transportable small unmanned surface vehicle (sUSV). The vehicle operates using Ardupilot open source software and can be used by local scientists and marine managers to map and monitor marine environments in shallow areas (<20 m) with commensurate visibility. The imaging system uses two Sony a6300 mirrorless cameras to collect stereo photos that can be later processed using photogrammetry software to create underwater high-resolution orthophoto mosaics and digital surface models. The propulsion system consists of two small brushless motors powered by lithium batteries that follow pre-programmed survey transects and are operated by a GPS-guided autopilot control board. Results from our project suggest the sUSV provides a repeatable, viable, and low-cost (<$3000 USD) solution for acquiring images of benthic environments on a frequent basis from directly below the water surface. These images can be used to create SfM models that provide very detailed images and measurements that can be used to monitor changes in biodiversity, reef erosion/accretion, and assessing health conditions.
Complex Modified Projective Synchronization of Fractional-Order Complex-Variable Chaotic System with Unknown Complex Parameters
Authors: Zhang Ruoxun , Feng Shiwen , Yang Shiping
Published: April 2019

This paper investigates the problem of complex modified projective synchronization (CMPS) of fractional-order complex-variable chaotic systems (FOCCS) with unknown complex parameters. By a complex-variable inequality and a stability theory for fractional-order nonlinear systems, a new scheme is presented for constructing CMPS of FOCCS with unknown complex parameters. The proposed scheme not only provides a new method to analyze fractional-order complex-valued systems but also significantly reduces the complexity of computation and analysis. Theoretical proof and simulation results substantiate the effectiveness of the presented synchronization scheme.
A Parasitic Resonator-Based Diamond-Shaped Microstrip Antenna for Microwave Imaging Applications
Authors: Mahmud Md Zulfiker , Islam Md Tarikul. , Almutairi Ali F. , Samsuzzaman Md , Acharjee U.K. , Islam Mohammad Tariqul
Published: April 2019

This study proposes a new parasitic resonator-based diamond-shaped microstrip patch antenna for ultra-wideband microwave imaging applications. The antenna consists of a diamond-shaped radiating patch, partial ground plane, and four-star shape parasitic elements. The use of parasitic elements improves the antenna performance in terms of the bandwidth and gain. The proposed prototype has a compact dimension of 30 × 25 × 1.6 mm3. The antenna achieves an overall bandwidth (S11<-10dB) of 7.6 GHz (2.7–10.3 GHz) with more than 4 dBi realized gain and 80% efficiency across the radiating bandwidth. The modified structures of the design extended the usable upper frequency from 9.7 GHz to 10.3 GHz, and the lower frequency is decreased from 3.4 GHz to 2.7 GHz with maintaining the omnidirectional radiation pattern. The design and simulation of the antenna are performed in the 3D electromagnetic simulator CST Microwave Studio. The proposed antenna is used for breast phantom measurement system to analyze the variation of backscattering signal and transmit-received pulses. The observation during the analysis of the numerical and measured data reveals that the designed antenna is a suitable candidate for ultra-wideband (UWB)-based microwave imaging applications.
Implementation of ARINC 659 Bus Controller for Space-Borne Computers
Authors: Jiang Shuang , Liu Shibin , Guo Chenguang , Fan Xu , Ma Teng , Tiwari Prayag
Published: April 2019

As one of the key technologies of Honeywell, the aeronautical radio incorporated (ARINC) 659 bus is popular in current space-borne computers. However, Honeywell does not design ARINC 659 bus controller separately, and there are only a few papers about FPGA-based ARINC 659 bus controllers. Accordingly, to promote the extremely high performance needs of space-borne computers, this paper designs an ARINC 659 bus controller chip which integrates two independent bus interface units (BIUs), one 8-bit MCU, and several peripheral interfaces (i.e., UART, SPI, and I2C). Because the two BIUs are identical and mutually checked, the symmetry problem is emphatically dealt with in the design of this bus controller, and effective timing convergence is realized, which makes the bus controller work reliably and stably. In addition, due to the circuit’s large scale, design for testability (DFT) is also considered. Accordingly, on-chip clock (OCC) and scanning compression test technique are used to realize the at-speed test and shorten the test time, respectively.
Impedance-Source DC-to-AC/DC Converter
Authors: Sivapriyan Rajendran , Elangovan Devaraj
Published: April 2019

This article presents a novel impedance-source-based direct current (DC)-to-alternating current (AC)/DC converter (Z-Source DAD Converter). The Z-Source DAD converter converts the input DC voltage into AC or DC with buck or boost in the load voltage. This Z-Source DAD conversion circuit is a single-stage power conversion system. This converter circuit converts the input DC voltage into variable-magnitude output DC voltage or converts the DC voltage into a variable-magnitude output AC voltage. The higher voltage magnitude in boost mode can be controlled by controlling the shoot-through (ST) state timing of the converter. MATLAB-Simulink simulation and microcontroller-based hardware circuit results are presented to demonstrate power conversion with the buck and boost features of the Z-Source DAD converter for both types of output voltages. The simulation and experimental results show that the Z-Source DAD converter converts the given DC supply into AC or DC with buck or boost in the output load voltage.
Analysis of a DC Converter with Low Primary Current Loss and Balance Voltage and Current
Authors: Lin Bor-Ren
Published: April 2019

A dc/dc pulse width modulation (PWM) circuit was investigated to realize the functions of reduced primary current loss and balanced voltage and current distribution. In the presented dc/dc converter, two full bridge pulse width modulation circuits were used with the series/parallel connection on the high-voltage/low-voltage side. The flying capacitor was adopted on the input side to achieve voltage balance on input split capacitors. The magnetic coupling element was employed to achieve current sharing between two parallel circuits. A capacitor-diode passive circuit was adopted to lessen the primary current at the commutated interval. The phase-shifted duty cycle control approach was employed to regulate load voltage and implement soft switching characteristics of power metal-oxide-semiconductor field-effect transistors (MOSFETs). Finally, the experimental results using a 1.68 kW prototype converter were obtained to confirm the performance and feasibility of the studied circuit topology.
A Compact Wideband SIW Bandpass Filter with Wide Stopband and High Selectivity
Authors: Huang Lei , Yuan Naichang
Published: April 2019

A novel method to design a wideband substrate integrated waveguide (SIW) bandpass filter (BPF) with compact size, wide stopband and high selectivity is presented. In this method some unique electromagnetic band-gap (EBG) cells are periodically etched on the top layer of SIW to realize a wide passband propagating below the equivalent waveguide cutoff frequency. By changing the configuration of EBG cells, undesired harmonics in upper stopband can be suppressed and a wideband BPF with wide stopband can be obtained. By symmetrically loading two complementary split ring resonators (CSRRs) on the tapered gradient lines of the input/output ports, a transmission zero near the passband can be introduced, and it makes the frequency selectivity of upper sideband improve significantly. As a verification, a wideband SIW BPF with a 3.02 GHz absolute bandwidth (ABW) and a 64.7% fractional bandwidth (FBW) centered at 4.67 GHz is designed, simulated, manufactured, and measured. The results of the experiment and simulation are in good agreement.
Damage Probability Assessment of Transmission Line-Tower System Under Typhoon Disaster, Based on Model-Driven and Data-Driven Views
Authors: Hou Hui , Geng Hao , Huang Yong , Wu Hao , Wu Xixiu , Yu Shiwen
Published: April 2019

Under the typhoon disaster, the power grid often has serious accidents caused by falling power towers and breaking lines. It is of great significance to analyze and predict the damage probability of a transmission line-tower system for disaster prevention and reduction. However, some problems existing in current models, such as complicated calculation, few factors, and so on, affect the accuracy of the prediction. Therefore, a damage probability assessment method of a transmission line-tower system under a typhoon disaster is proposed. Firstly, considering the actual wind load and the design wind load, physical models for calculating the damage probability of the transmission line and power tower are established, respectively based on model-driven thought. Then, the damage probability of the transmission line-tower system is obtained, combining the transmission line and power tower damage probability. Secondly, in order to improve prediction accuracy, this paper analyzes the historical sample data containing multiple influencing factors, such as geographic information, meteorological information, and power grid information, and then obtains the correction coefficient based on data-driven thought. Thirdly, the comprehensive damage probability of the transmission line-tower system is calculated considering the results of model-driven and data-driven thought. Ultimately, the proposed method is verified to be effective, taking typhoon ‘Mangkhut’ in 2018 as a case study.
Nature-Inspired MPPT Algorithms for Partially Shaded PV Systems: A Comparative Study
Authors: Pathy Somashree , Subramani C. , Sridhar R. , Thamizh Thentral T. M. , Padmanaban Sanjeevikumar
Published: April 2019

PV generating sources are one of the most promising power generation systems in today’s power scenario. The inherent potential barrier that PV possesses with respect to irradiation and temperature is its nonlinear power output characteristics. An intelligent power tracking scheme, e.g., maximum power point tracking (MPPT), is mandatorily employed to increase the power delivery of a PV system. The MPPT schemes experiences severe setbacks when the PV is even shaded partially as PV exhibits multiple power peaks. Therefore, the search mechanism gets deceived and gets stuck with the local maxima. Hence, a rational search mechanism should be developed, which will find the global maxima for a partially shaded PV. The conventional techniques like fractional open circuit voltage (FOCV), hill climbing (HC) method, perturb and observe (P&O), etc., even in their modified versions, are not competent enough to track the global MPP (GMPP). Nature-inspired and bio-inspired MPPT techniques have been proposed by the researchers to optimize the power output of a PV system during partially shaded conditions (PSCs). This paper reviews, compares, and analyzes them. This article renders firsthand information to those in the field of research, who seek interest in the performance enhancement of PV system during inhomogeneous irradiation. Each algorithm has its own advantages and disadvantages in terms of convergence speed, coding complexity, hardware compatibility, stability, etc. Overall, the authors have presented the logic of each global search MPPT algorithms and its comparisons, and also have reviewed the performance enhancement of these techniques when these algorithms are hybridized.
Experimental Investigation of a Small-Scale ORC Power Plant Using a Positive Displacement Expander with and without a Regenerator
Authors: Collings Peter , Mckeown Andrew , Wang Enhua , Yu Zhibin
Published: April 2019

While large-scale ORC power plants are a relatively mature technology, their application to small-scale power plants (i.e., below 10 kW) still encounters some technical challenges. Positive displacement expanders are mostly used for such small-scale applications. However, their built-in expansion ratios are often smaller than the expansion ratio required for the maximum utilisation of heat sources, leading to under expansion and consequently higher enthalpy at the outlet of the expander, and ultimately resulting in a lower thermal efficiency. In order to overcome this issue, one possible solution is to introduce an internal heat exchanger (i.e., the so-called regenerator) to recover the enthalpy exiting the expander and use it to pre-heat the liquid working fluid before it enters the evaporator. In this paper, a small-scale experimental rig (with 1-kW rated power) was designed and built that is capable of switching between regenerative and non-regenerative modes, using R245fa as the working fluid. It has been tested under various operating conditions, and the results reveal that the regenerative heat exchanger can recover a considerable amount of heat when under expansion occurs, increasing the cycle efficiency.
Coal Chemical-Looping with Oxygen Uncoupling (CLOU) Using a Cu-Based Oxygen Carrier Derived from Natural Minerals
Authors: Wang Ping , Howard Bret , Means Nicholas , Shekhawat Dushyant , Berry David
Published: April 2019

Chemical-looping with oxygen uncoupling (CLOU) is considered a promising technology to burn solid fuels with improved CO2 capture and has the potential to improve fuel conversion and reaction rates. Cu-based oxygen carriers (Cu-OC) are often used in solid fuel CLOU. This study focused on investigating Cu-OC derived from a natural mineral for solid fuel CLOU because of their potentially lower cost compared to synthetic OCs. Reactivity and recyclability of a natural ore-derived Cu-OC on coal char (Powder River Basin sub-bituminous coal) were studied at 900 °C in Ar and air using TGA-QMS and fixed-bed reactor-QMS for five cycles. Cu-OC was prepared by simply heating chalcopyrite in air. Chalcopyrite is one of the principle copper sulfide ores and one of the primary ores for copper. The prepared Cu-OC had primarily CuO and CuFe2O4 (CuOFe2O3) as active compounds based on XRD analysis and an oxygen capacity 3.3% from oxygen uncoupling. The carbon conversion efficiency Xc was 0.94 for reduction at a ratio of Cu-OC to char ϕ = 75 and the product gas was primarily CO2 with trace O2. The reactivities and the rates were similar for five redox cycles. These results indicate that the natural ore-derived material with low cost has potential as a competitive oxygen carrier in solid fuel CLOU based on its reactivity in this study.
Transboundary Exchanges of Renewable Energy and Desalinated Water in the Middle East
Authors: Katz David , Shafran Arkadiy
Published: April 2019

The Levant area of the Middle East suffers from both chronic water scarcity and high population growth. It is also a region highly dependent of fossil fuels. In order to address current and expected water demands, several countries in the region, including Israel, Jordan and the Palestinian Authority (PA), are depending increasingly on desalination, which is expected to intensify energy consumption and energy related emissions. Given that the region also benefits from high levels of solar irradiation nearly year-round, much attention has been given to the possibility of developing renewable energy in general and for desalination specifically. This paper presents partial results of a pre-feasibility study assessing the prospects of transfers of desalinated water from Israel and/or the PA, which have access to the Mediterranean Sea, to Jordan, in exchange for renewable solar-produced electricity from Jordan, which, unlike its neighbors, has an abundance of available open space suitable for solar production. The analysis shows that single-axis tracking photovoltaic (PV) systems appear to be the most economically feasible option. Moreover, the study shows that the proposed idea of international cooperation and water-energy exchanges, while facing political obstacles, could provide numerous economic, environmental and geopolitical benefits to all parties involved. As such, an arrangement such as that examined may be a more promising means of promoting both desalination and renewable energy than if each country unilaterally develops desalination and renewable energy in isolation from one another.
An Energy Management System for Residential Autonomous DC Microgrid Using Optimized Fuzzy Logic Controller Considering Economic Dispatch
Authors: Al-Sakkaf Shehab , Kassas Mahmoud , Khalid Muhammad , Abido Mohammad A.
Published: April 2019

This work presents the operation of an autonomous direct current (DC) DC microgrid for residential house controlled by an energy management system based on low complexity fuzzy logic controller of only 25-rules to manage the power flow that supply house load demand. The microgrid consists of photovoltaic (PV), wind turbine, fuel cell, battery energy storage and diesel generator. The size of the battery energy storage is determined based on the battery sizing algorithm depending on the generation of renewables during all seasons of the year in the eastern region of Saudi Arabia. Two scenarios are considered in this work. In the first scenario: the microgrid consists of solar PV, wind turbine, battery energy storage and fuel cell. The fuzzy logic controller is optimized using an artificial bee colony technique in order to increase the system energy saving efficiency and to reduce the cost. In the second scenario: wind turbine is replaced by a diesel generator, also the rated power of the fuel cell is reduced. In this scenario, a new method is proposed to reduce the generation cost of the dispatchable sources in the microgrid by considering economic dispatch within the optimized fuzzy logic energy management system. To obtain the most suitable technique for solving the economic dispatch problem, three optimization techniques were used which are particle swarm optimization, genetic algorithm and artificial bee colony based on real environmental data and real house load demand. A comparison in terms of energy saving between the two scenarios and a comparison in terms of cost reduction between conventional economic dispatch method and the proposed method are presented.
An Optimized Coordination Strategy between Line Main Protection and Hybrid DC Breakers for VSC-Based DC Grids Using Overhead Transmission Lines
Authors: Zheng Xiangyu , Jia Rong , Gong Linling , Zhang Guangru , Pei Xiangyu
Published: April 2019

Compared with alternating current (AC) power grids, the voltage-sourced converter (VSC)-based direct current (DC) grid is a system characterized by “low damping”, as a result, once there is a short-circuit fault on the DC transmission line, the fault current will rise more sharply and the influence range will be much wider within the same time scale. Moreover the phenomenon that a local fault causes a whole power grid outage is more likely to occur. Overhead transmission lines (OHLs) have been regarded as the mainstream form of power transmission in future high-voltage, large-capacity and long-distance VSC-based DC grids. However, the application of overhead transmission lines will inevitably lead to a great increase in the probability of DC line failure. Therefore, research on how to isolate the DC fault line quickly is of great significance. Based on the technology route for fault line isolation using DC breakers, on the basis of in-depth analysis of traditional coordination strategy, an optimized coordination strategy between line main protection and a hybrid DC breaker for VSC-based DC grids using overhead transmission lines is proposed in this paper, which takes the start-up output signal of line main protection as the pre-operation instruction of the corresponding hybrid DC breaker. As a result, the risks of blockage of the modular multilevel converter (MMC) closer to the fault position and of damage to power electronic devices in main equipment can be reduced effectively. Finally, the proposed coordination strategy was verified and analyzed through simulation.
Root Biomechanical Traits in a Montane Mediterranean Forest Watershed: Variations with Species Diversity and Soil Depth
Authors: Moresi Federico Valerio , Maesano Mauro , Matteucci Giorgio , Romagnoli Manuela , Sidle Roy C. , Scarascia Mugnozza Giuseppe
Published: April 2019

Plant roots play a key role in stabilizing slopes, particularly in the Mediterranean region, characterized by rough and unstable terrain. However, forest species differ in their stabilizing capacities. The purpose of this study is to fill the gap of knowledge on root biomechanical properties of relevant Mediterranean trees and shrubs in relation to slope stability. Root specimens of typical montane Mediterranean tree and shrub species were sampled in Southern Italy. Root characteristics, such as tensile strength (Tr) and root area ratio (RAR), were assessed from live roots sampled in trenches, while root cohesion was calculated. Power law functions yielded the best fit for the relationship of Tr versus root diameter; however, no significant relationship was found between root strength and root moisture content. RAR varied amongst different tree and shrub species. Roots of Quercus cerris L. were the most resistant to breaking under tension, while roots of Ilex aquifolium L. had the highest tensile strength among all shrub species. Results provide quantitative information on the role of root systems of montane Mediterranean forest species in stabilizing soils and will improve modeling of landslide susceptibility to the prevention and mitigation of natural hazards in mountain environments.
Onset of Convection in an Inclined Anisotropic Porous Layer with Internal Heat Generation
Authors: Storesletten Leiv , Rees D. Andrew S.
Published: April 2019

The onset of convection in an inclined porous layer which is heated internally by a uniform distribution of heat sources is considered. We investigate the combined effects of inclination, anisotropy and internal heat generation on the linear instability of the basic parallel flow. When the Rayleigh number is sufficiently large, instability occurs and a convective motion is set up. It turns out that the preferred motion at convection onset depends quite strongly on the anisotropy ratio, ξ , and the inclination angle. When ξ < 1 the preferred motion is in the form of longitudinal rolls for all inclinations. When ξ > 1 transverse rolls are preferred for small inclinations but, at high inclinations, longitudinal rolls are preferred. At intermediate inclinations the preferred roll orientation varies smoothly between these two extremes.
Statistical Mechanics Involving Fractal Temperature
Authors: Khalili Golmankhaneh Alireza
Published: April 2019

In this paper, the Schrödinger equation involving a fractal time derivative is solved and corresponding eigenvalues and eigenfunctions are given. A partition function for fractal eigenvalues is defined. For generalizing thermodynamics, fractal temperature is considered, and adapted equations are defined. As an application, we present fractal Dulong-Petit, Debye, and Einstein solid models and corresponding fractal heat capacity. Furthermore, the density of states for fractal spaces with fractional dimension is obtained. Graphs and examples are given to show details.
Treading Other Paths within Afro-Diasporic Contexts: Unilab Students’ Experiences, Challenges, and Perspectives
Authors: Santos Souza Cristiane
Published: April 2019

In this paper, I discuss some of the processes that characterized the creation and consolidation of the University of International Integration of Afro-Brazilian Lusophony (Unilab) in Bahia, as part of the expansion project of public higher education in Brazil that was implemented during the Lula presidency (2003–2010) and defined in the government’s internationalization and regionalization project. To this end, I reviewed the literature and institutional documents from the past four years and analyzed observations of daily campus life. I highlight some challenges as well as possibilities for young international students, particularly young Africans from the five Portuguese-speaking countries, and for Brazilian nationals, too, which arise from the implementation of this public higher education expansion program in the Recôncavo Baiano region. Finally, I conclude with observations about the cultural diversity and social reality inherent to the context and discuss the conceptual and practical challenges and possibilities arising from that intercultural reality.
Tamar Yoseloff as Ekphrasist, and Her Hidden Sweetheart: ‘I Took His Heart, Placed It/in an Ivory Case’ †
Authors: Huen Antony
Published: April 2019

This article investigates Tamar Yoseloff’s different engagements with the visual arts in her ekphrastic poems by focusing on her first collection Sweetheart (1998). There are many critical studies about the poetic ekphrastic tradition, but there is rarely an in-depth investigation into a poet’s dedication to ekphrasis. This article suggests that Tamar Yoseloff’s dedication to ekphrasis is traceable to her earliest work. With a close analysis of three poems from Sweetheart—‘The Two Fridas’, ‘The Arnolfini Marriage’ and ‘The Visible Man’, I argue that the book is a sustained exploration of the autobiographical and biographical enigmas represented in visual artworks and artefacts, as well as our identification with these enigmas. It is hoped that this article could initiate a discussion about the tradition of poets dedicated to ekphrasis being as long as the tradition of modern ekphrasis.
Feasibility and Acceptability of ‘Opt-In’ Referrals for Stop Smoking Support in Pregnancy
Authors: Campbell Katarzyna Anna , Orton Sophie , Bowker Katharine , Cooper Sue , Coleman Tim
Published: April 2019

Background: International guidelines recommend that following an early-pregnancy ‘opt-out’ referral for smoking cessation support, pregnant women who smoke should also be offered referrals at subsequent antenatal appointments (‘opt-in’ referrals). We assessed feasibility and acceptability of introducing ‘opt-in’ self-referral forms to stop smoking services (SSS) in antenatal clinics. Method: A ‘before–after’ service evaluation and qualitative interviews. ‘Opt-in’ self-referral forms were distributed by reception staff to women attending antenatal ultrasound appointments. We collected hospital/SSS data for the study period and a comparison period 12 months prior. Reception staff were interviewed and data analyzed thematically. Results: Over 6500 women entered antenatal care in each period; ~15% smoked and ~50% of those who smoked were referred to SSS at their first appointment. In the study period, 17.4% of women completed ‘opt-in’ forms. Of these 17.3% smoked, and 23.1% of those who smoked requested a referral. The staff thought new procedures had minimal impact on workload, but were easy to forget. They believed the pathway would be better delivered by midwifery staff, with additional information/advice to improve engagement. Conclusions: ‘Opt-in’ referrals in later pregnancy result in significant numbers of women who smoke indicating interest in smoking cessation support. Additional training and support is necessary to motivate reception staff to oversee self-referral pen-and-paper procedures effectively.
Environmental Effects of the Livestock Industry: The Relationship between Knowledge, Attitudes, and Behavior among Students in Israel
Authors: Dopelt Keren , Radon Pnina , Davidovitch Nadav
Published: April 2019

The livestock industry has numerous and diverse impacts on the environment. In a cross-sectional study using an online questionnaire, 361 students were asked about their knowledge, attitudes, and behavior related to the environmental impact caused by livestock industry. The data were analyzed using correlations, t-tests for independent samples, and linear regression models. We found that students have almost no knowledge about the environmental impact of the food they consume, their attitudes are moderately pro-environmental, yet they are not strict about pro-environmental behavior. Students with higher levels of environmental knowledge demonstrated more pro-environmental attitudes and behavior; attitudes mediate the relationship between level of knowledge and behavior with respect to environmental pollution caused by the livestock industry. In addition, participants that rear/reared animals demonstrated more knowledge and pro-environmental attitudes and behavior, and women demonstrated more pro-environmental attitudes and behavior than men. There is a need to raise awareness of the environmental and health impacts caused by livestock industry. An introductory course on environmental science should be integrated into different academic study programs. Further research should be conducted among additional population sectors.
Effect of Animal-Assisted Therapy on Patients in the Department of Long-Term Care: A Pilot Study
Authors: Machová Kristýna , Procházková Radka , Eretová Petra , Svobodová Ivona , Kotík Ilja
Published: April 2019

Long-term hospital stays might have a negative psychosocial impact on our patients. One way to positively activate hospitalized patients is to introduce animal-assisted therapy (AAT). A total of 72 individuals participated in this research. The experimental group comprised 33 patients (8 males, 25 females), while the control group contained 39 patients (11 men, 28 women). The participants in the control group were aged from 58 to 100 years and the experimental group featured participants aged from 51 to 95, for whom AAT was included alongside standard care. Blood pressure, heart rate, Barthel index, and general mood were measured in both groups. Results did not reveal any changes in blood pressure, heart rate, or Barthel index in comparison between groups. A great influence was noted in assessment of the mood of the patients. The inclusion of AAT did not affect physiological parameters, but it exerted a significant effect on the psychological well-being of the patients.
The Effects of Short-Term Immunosuppressive Therapy on Redox Parameters in the Livers of Pregnant Wistar Rats
Authors: Szypulska-Koziarska Dagmara , Wilk Aleksandra , Kabat-Koperska Joanna , Kolasa-Wołosiuk Agnieszka , Wolska Jolanta , Wiszniewska Barbara
Published: April 2019

Immunosuppressive drugs are widely used to avoid graft rejection, but they are also known to be strongly hepatotoxic. The goal of the current study was to determine: (i) the immunoexpression of SOD1, CAT, GPX1; (ii) the concentration of MDA, GSH; (iii) the activity of SOD, CAT, GPX, in the native liver of a pregnant female rats undergoing immunosuppressive therapy. The study was based on archival material obtained from Department of Nephrology, Transplantology and Internal Medicine of the Independent Public Clinical Hospital No. 2 at the Pomeranian Medical University in Szczecin, Poland. The study was carried out on 32 female rats exposed to oral administration of immunosuppressants two weeks before and during pregnancy. The percentage of SOD1 immunopositive hepatocytes in rats treated with cyclosporine A, mycophenolate mofetil, everolimus, and glucocorticosteroid was significantly elevated above that of the control rats. The concentration of MDA in the liver of animals exposed to cyclosporine A, everolimus, and glucocorticosteroid was significantly higher than in other groups. Among the groups of dams treated with immunosuppressive drugs, the highest significant concentration of GSH was found in the livers of rats treated with cyclosporine A, mycophenolate mofetil and glucocorticosteroid. Immunosuppressive therapy during pregnancy affects the oxidoreductive balance in the livers of rats, depending on the regimen used.