bluuebunny/crossref_metadata_2025 huggingface dataset:
Governing the Armenian Question through Passports in the Late Ottoman Empire (1876–1908)
Authors: Yılmaz İIkay
Published: December 2019

The literature on the history of passports has been generally discussed in the context of freedom of movement around the globe during the 19th century. However, with its administrative regulations and practices, the Ottoman Empire offered a different view of passports and mobility controls. Through perceiving new threats from the political issues of the late 19th century and directing its attention mainly at the Armenian and Macedonian Questions, one of the critical issues facing the Ottoman government during the Hamidian Era (1876–1908) was controlling the geographic mobility of the individuals who were perceived as a threat based on Ottoman security policies. This paper brings a particular case of this history into focus: the administrative control of the mobility of Armenians. Despite the fact that extensive research has been done on the Armenian Question, so far, little has been written on the policies restricting their mobility. This paper aims to explore the passport regulations and practices to shed light onto the relationship between state formation, Ottoman threat perceptions and the marginalisation of the Armenian community. I offer a new look at the securitisation of the Armenian Question.
Intramarital Status Differences Across Africa's Educational Expansion
Authors: Lopus Sara , Frye Margaret
Published: December 2019

Objective:This article documents how intramarital differences in educational status vary across Africa's heterogeneous educational expansion, which has encompassed an enormous breadth of educational opportunities during the past 50 years.

Background:Educational expansion influences intramarital status differences both by altering the educational composition of men and women and by reconfiguring the social conventions associated with a given educational context. Status differentials between marital partners can influence spousal well‐being and, in the aggregate, determine the extent to which marriage provides a pathway to upward social mobility.

Method:Using Demographic and Health Survey data representing 32 sub‐Saharan African countries and 5 decades of birth cohorts, the article examines the prevalence and propensity of educational pairings as a function of educational access (the percentage of a cohort who ever attended school) and wife's education level.

Results:Educational expansion created gendered changes in educational compositions of married individuals, which led to increased prevalence of hypergamy (wives who married “up”) in most countries. Educational expansion has also led hypogamous marriages to become less of a social aberration: in lower education contexts (but less so in higher education contexts), conventions lead women to “marry down” at far lower rates than would be expected based on the sex‐specific compositions of husbands and wives.

Conclusion:Educational attainment remains a central determinant of social positioning in African society. However, as schooling expands across the continent, social conventions regarding educational status are playing a weakening role in determining who marries whom.
Into the bloom: Molecular response of pelagic tunicates to fluctuating food availability
Authors: Sordino Paolo , D'Aniello Salvatore , Pelletier Eric , Wincker Patrick , Nittoli Valeria , Stemmann Lars , Mazzocchi Maria Grazia , Lombard Fabien , Iudicone Daniele , Caputi Luigi
Published: December 2019

The planktonic tunicates appendicularians and thaliaceans are highly efficient filter feeders on a wide range of prey size including bacteria and have shorter generation times than any other marine grazers. These traits allow some tunicate species to reach high population densities and ensure their success in a favourable environment. However, there are still few studies focusing on which genes and gene pathways are associated with responses of pelagic tunicates to environmental variability. Herein, we present the effect of food availability increase on tunicate community and gene expression at the Marquesas Islands (South‐East Pacific Ocean). By using data from the Tara Oceans expedition, we show that changes in phytoplankton density and composition trigger the success of a dominant larvacean species (an undescribed appendicularian). Transcriptional signature to the autotroph bloom suggests key functions in specific physiological processes, i.e., energy metabolism, muscle contraction, membrane trafficking, and proteostasis. The relative abundance of reverse transcription‐related Pfams was lower at bloom conditions, suggesting a link with adaptive genetic diversity in tunicates in natural ecosystems. Downstream of the bloom, pelagic tunicates were outcompeted by copepods. Our work represents the first metaomics study of the biological effects of phytoplankton bloom on a key zooplankton taxon.
Cervical Spinal Cord Stimulator Lead Migration and Transection Adjacent to the Foramen Magnum: A Case Report
Authors: Padalia Devang , Kesayan Tigran , Martin Aaron J. , Shah Neal
Published: December 2019

Background

Spinal cord stimulation (SCS) is a relatively safe therapy for the treatment of pain but has the potential for several complications, including lead migration and breakage. While instances of lead breakage and electrode shearing have been described, there are no reported cases of stimulator lead transection and migration to the foramen magnum.

Aims

We describe the case of a 53‐year‐old woman who reported that her cervical spinal cord stimulator was no longer functioning after a traumatic fall.

Case

Fluoroscopy of the neck revealed that one of the MRI conditional leads had migrated cephalad, and the distal aspect appeared to be transected. This was confirmed by computerized tomography, which showed a transected portion of the lead in the epidural space, just inferior to the posterior aspect of the foramen magnum. An SCS device revision was performed to replace the lead, but the distal transected tip was left in place in the epidural space adjacent to the foramen magnum to avoid complications of retrieval.

Discussion/Conclusion

Given the location of the transected portion of the lead, we recommended avoiding MRI imaging. In addition, we advised the patient that a repeat x‐ray may be necessary if she has increased neck pain or any other concerning symptoms. In this report, we discuss the known complications with SCS, as well as management of a retained lead fragment.
Survey of a nutrition management method for very low birthweight infants: Status before wide use of breast milk banks in Japan
Authors: Oikawa Kosuke , Sakurai Motoichiro , Murakawa Tetsuro , Kidokoro Reita , Nakano Yuya , Asai Hideyuki , Ochiai Hirotaka , Shirasawa Takako , Yoshimoto Takahiko , Minoura Akira , Kokaze Akatsuki , Mizuno Katsumi
Published: December 2019

Background

The importance of breast‐feeding for very low birthweight (VLBW) infants has been pointed out. Some overseas studies suggested that the standardization of enteral nutrition (EN) leads to improved prognosis in VLBW infants. In Japan, however, physicians in charge of infants are responsible for making nutrition management decisions on an individual basis. We conducted an online survey to clarify the course of nutrition management of VLBW infants currently implemented in Japan.

Methods

We mailed a notice to 300 representative neonatologists throughout Japan requesting their participation in the online survey. On the survey website, neonatologists responded to questions regarding the nutritional strategy for five birthweight groups (less than 500 g, 500–749 g, 750–999 g, 1,000–1,249 g and 1,250–1,499 g).

Results

Responses were recieved from 137 neonatologists. The first choice for EN up to 1 week after birth was breast milk regardless of birthweight (92.0% for 1,250–1,499 g to 95.6% for 500–999 g). More than 30% of the respondents answered that they fast infants who weigh <750 g at birth or feed them with other mothers’ breast milk until their own mother’s milk becomes available. The lower the birthweight, the later EN is started, and the greater the number of days to establish EN.

Conclusion

The lower the birthweight, the more difficult it is to feed infants their own mother’s milk and the later the EN is started. If donor milk is supplied in a stable manner, it takes fewer days to establish EN.
An empowerment program for family caregivers of people with dementia
Authors: Yoon Heun Keung , Kim Gwang Suk
Published: December 2019

Objectives

Family caregivers of people with dementia (PWD) often feel powerless and experience decreased well‐being. Our aim was to develop an intervention program based on the caregiver empowerment model (CEM) and apply it with the Korean caregivers to evaluate its effects.

Design and Sample

The study population comprised 115 family caregivers (experimental group, n = 35, control group 1, n = 40, control group 2, n = 40).

Methods

Using an experimental design with two control groups. The experimental group received a 12‐week program including intensive counseling, education, and telephone calls. The control group 1 (CG1) received usual service. The control group 2 (CG2) was provided with a handbook during the first week. A mixed‐effects model was used to clarify longitudinal changes in participants' outcomes.

Results

The experimental group showed significantly increased caregiving appraisal (effect size in CG1 = −7.25; CG2 = −5.63), caregiving attitude (CG1 = −21.47; CG2 = −17.79), self‐efficacy (CG1 = −12.42; CG2 = −10.12), and well‐being (CG1 = −4.33; CG2 = −2.35) after the program.

Conclusions

The empowerment program can be used to promote family caregivers' positive adaptation and to help caregivers who care for PWD to effectively cope with their problems.
Post Gondwana breakup evolution of the SE Australia rifted margin revisited
Authors: McMillan Malcolm , Gleadow Andrew , Kohn Barry , Seiler Christian
Published: December 2019

Low‐temperature thermochronology (LTT) is commonly used to investigate onshore records of continental rifting and geomorphic evolution of passive continental margins. The SE Australian passive margin, like many others, has an elevated plateau separated from the coastal plain by an erosional escarpment, presumed to originate through Cretaceous rifting prior to Tasman Sea seafloor spreading. Previous LTT studies have focused on reconciling thermal histories with development of the present‐day topography. New apatite LTT data along an escarpment‐to‐coast transect define a classic “boomerang” (mean track length vs. fission‐track age), indicating variable overprinting of late‐Palaeozoic cooling ages by a younger, mid‐Cretaceous cooling event. Regionally, however, the boomerang trend diverges NNW away from the coast and crosses the escarpment, implying the underlying thermal history pre‐dates escarpment formation and is largely independent from post‐breakup landscape evolution. We suggest that Cretaceous cooling might relate to erosion of Permo‐Triassic sedimentary cover from a formerly more extensive Sydney Basin.
EWSE and Uncertainty and Disturbance Estimator Based Pitch Angle Control for Wind Turbine Systems Operating in Above-Rated Wind Speed Region
Authors: Jiao Xuguo , Yang Qinmin , Fan Bo , Chen Qi , Sun Yong , Wang Lin
Published: December 2019

As wind energy becomes a larger part of the world's energy portfolio, the control of wind turbines is still confronted with challenges including wind speed randomness and high system uncertainties. In this study, a novel pitch angle controller based on effective wind speed estimation (EWSE) and uncertainty and disturbance estimator (UDE) is proposed for wind turbine systems (WTS) operating in above-rated wind speed region. The controller task is to maintain the WTS's generator power and rotor speed at their prescribed references, without measuring the wind speed information and accurate system model. This attempt also aims to bring a systematic solution to deal with different system characteristics over wide working range, including extreme and dynamic environmental conditions. First, support vector machine (SVR) based EWSE model is developed to estimate the effective wind speed in an online manner. Second, by integrating an UDE and EWSE model into the controller, highly turbulent and unpredictable dynamics introduced by wind speed and internal uncertainties is compensated. Rigid theoretical analysis guarantees the stability of the overall system. Finally, the performance of the novel pitch control scheme is testified via the professional Garrad Hassan (GH) bladed simulation platform with various working scenarios. The results reveal that the proposed approach achieves better performance in contrast to traditional L1 adaptive and proportional-integral (PI) pitch angle controllers.
Surrogate Modeling for Capacity Planning of Charging Station Equipped With PV and Hydropneumatic Energy Storage
Authors: Chen Yang , Dababneh Fadwa , Zhang Bei , Kassaee Saiid , Smith Brennan T. , Liu Xiaobing , M. Momen Ayyoub
Published: December 2019

Due to the promising potential for environmental sustain-ability, there has been a significant increase of electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEV) in the market. To support this increasing demand for EVs and PHEVs, challenges related to capacity planning and investment costs of public charging infrastructure must be addressed. Hence, in this paper, a capacity planning problem for EV charging stations is developed and aims to balance current capital investment costs and future operational revenue. The charging station considered in this work is assumed to be equipped with solar photovoltaic panel (PV) and an energy storage system which could be electric battery or the recently invented hydro-pneumatic energy storage (GLIDES, Ground-Level Integrated Diverse Energy Storage) system. A co-optimization model that minimizes investment and operation cost is established to determine the global optimal solution while combining the capacity and operational decision making. The operational decision making considers EV mobility which is modeled as an Erlang-loss system. Meanwhile, stochastic programming is adopted to capture uncertainties from solar radiation and charging demand of the EV fleet. To provide a more general and computationally efficient model, main configuration parameters are sampled in the design space and then fixed in solving the co-optimization model. The model can be used to provide insights for charging station placement in different practical situations. The sampled parameters include: the total number of EV charging slots, the PV area, the maximum capacity of the energy storage system, and daily mean EV arrival number in the Erlang-loss system. Based on the sampled parameter combinations and its responses, black-box mappings are then constructed using surrogate models (RBF, Kriging etc). The effectiveness of proposed surrogate modeling approach is demonstrated in the numerical experiments.
Particle Lift Challenges and Solutions for Solid Particle Receiver Systems
Authors: Christian Joshua M. , Sment Jeremy , Ho Clifford K. , Haden Lonnie , Albrecht Kevin
Published: December 2019

Particle receiver systems require durable, reliable, and cost-effective particle transport equipment. These lifts are critical pieces of equipment to transport the particles from the heat exchanger back into the receiver. There are challenges that must be overcome with any particle lift device including high temperatures (800°C), particle load and friction, and erosion from particle contact. There are several options commercially available for particle systems including a screw-type vertical elevator, bucket lift vertical elevator, and skip-hoist-style bulk vertical lifts. Two of the elevator types (screw and bucket) have been tested at the National Solar Thermal Test Facility (NSTTF) at Sandia National Laboratories (SNL) in Albuquerque, NM. The two elevators are currently in operation on the 1 MWth falling particle receiver at the Solar Tower. The screw-type elevator consists of a stationary internal screw with an outer casing that rotates about the screw. The frictional forces from the casing rotation drives the particles upward along the flights of the screw. The casing rotational velocity is variable which allows for mass flow rate control. Identified issues with the screw-type elevator include particle attrition, uneven loading at the inlet causes casing deflection, bearing deformation due to casing deformation, and motor stalling due to increased resistance on the casing. The SNL bucket elevator is rated for temperatures up to 600 °C and consists of steel buckets and a steel drive chain capable of lifting particles at a rate of 8 kg/s. Identified issues with the bucket type elevator include discrete (non-continuous) discharge of the particles and a non-adjustable flow rate. A skip hoist type elevator has been studied previously and seems like the most viable option on a large scale (50–100MWth power plant) with a non-continuous particle discharge. Different control scenarios were explored with the variable frequency drive of the screw-type elevator to use it as a particle-flow control device. The objective was to maintain the feed hopper inventory at a constant value for steady flow of particles through the receiver. The mass flow rate was controlled based on feedback from measurements of particle level (mass) inside the top hopper.
Design Features of the World’s First Commercial Concentrating Solar Power Plant Using the Particle Heating Receiver Concept
Authors: Al-Ansary Hany , El-Leathy Abdelrahman , Jeter Sheldon , Golob Matthew , Nguyen Clayton , Djajadiwinata Eldwin , Alaqel Shaker , Saeed Rageh , Abdel-Khalik Said , Al-Suhaibani Zeyad , Danish Syed , Saleh Nader , Al-Balawi Ahmed , Al-Harthi Fahad , Bashraheel Salem , Gandayh Hatim
Published: December 2019

Particle-based power tower systems are a promising technology that can allow operation of concentrating solar power (CSP) systems at temperatures higher than what today’s commercial molten salt systems can achieve, making them suitable for use in a variety of applications, including supercritical CO2 cycles, air Brayton cycles, and high-temperature process heat. In this concept, particles, instead of molten salt, are heated by the concentrated sunlight. In 2015, this concept was successfully tested at Sandia National Laboratories. In the mean time, an integrated system incorporating a particle heating receiver, a particle-to-air heat exchanger and a 100-kWe microturbine was designed, built, and tested at King Saud University in Riyadh, Saudi Arabia. The integrated system was run in 2018, and results from that test campaign were very promising, with temperatures of the particles leaving the receiver exceeding 600°C despite a number of challenges. The utility sponsoring the project is now planning to move forward with building a 1-MWe plant using the same concept, thereby moving closer to large-scale deployment, and making this facility the world’s first commercial concentrating solar power plant that uses the particle heating receiver concept. Moving from a 100-kWe scale to a 1-MWe scale requires modifications to the design of some components. The most likely plant location is the city of Duba in northwestern Saudi Arabia where the average daily total DNI is 7,170 Wh/m2 and an integrated solar combined cycle power plant exists on the premises. This paper discusses the design features of the main components of the new plant. Those features include a north field design, a 7.22-m2 single-sheet heliostat design, a cavity receiver to improve receiver efficiency by reducing radiative and convective losses, temperature-based particle flow regulation within the receiver, six hours of full-load thermal energy storage, with the tanks integrated into the tower structure and made of cost-effective masonry material, a shell-and-tube particle-to-air heat exchanger, a 45% efficiency recuperated intercooled gas turbine, and a high-temperature bucket elevator. The heliostat field was optimized using SolarPILOT. Results show that 1,302 heliostats are needed. The aperture area was found to be approximately 5.7 m2, while the total illuminated receiver surface area is about 16.8 m2. This design was found to be capable of achieving the particle temperature rise of 416°C, which is necessary to allow the turbine to rely entirely on the solar field to bring the temperature of air to the firing temperature of the turbine, thereby eliminating the need for fuel consumption except for back-up and for assistance at off-design conditions.
Intensity Distribution From a Single-Bulb Solar Simulator Identification Through Inverse Ray Tracing
Authors: Abuseada Mostafa , Ozalp Nesrin
Published: December 2019

Through the flux characterization of a high flux solar simulator, all directional information of the flux distribution is lost. Therefore, an experimental approach is necessary to restore the directional information. In this study, 13 heat flux maps were experimentally obtained from a 10 kWe Xenon arc solar simulator through an indirect flux mapping technique, implementing the use of one Lambertian target. The formulation of the inverse problem of experimentally determining the intensity distribution at the focal plane is presented. In addition, a Monte Carlo ray tracing in-house code modeling the Xenon arc is developed and used to generate the experimentally obtained flux maps and intensity at the focal plane to be used as a reference. Two intensity interpolation schemes were examined; a zeroth and first-order schemes. It is shown that a first order interpolation unnecessary complicates the inverse problem. The percentage error reduced from 90.9% to 82.6% when changing the interpolation scheme from a first to zeroth-order, in addition to a five times reduction in computational time. Furthermore, a new approach of constraining the formulated system of equations with an equality constraint that works by eliminating some of the intensity values that cannot be traced back to the ellipsoidal reflector is proposed. Therefore, it can be used as a technique to change the ill-conditioned problem to a well-conditioned one, without depending heavily on Tikhonov regularization methods. This new approach provided intensity values at the focal plane with a reduced percentage error from 52.2% to 30.4% for the zeroth-order interpolation scheme.
Academic Building Equipment Standardization for Sustainability
Authors: Manegdeg Ferdinand G. , Balbarona Juvy A. , Ibañez Roderaid T.
Published: December 2019

The University of the Philippines is the Philippines’ national university. It is mandated to be the leader in innovation and research. The electricity consumption of the flagship campus, the University of the Philippines Diliman, rose from 13.97 GWh in 2006 to 15.26 GWh by 2015 [1]. The electricity consumption must be managed as the university desires more students to graduate, do progressive research and creative works, and produce quality extension services. An appropriate energy policy incorporating minimum equipment standards in procuring energy consuming devices is wanting. Standardization controls the varying energy demand of equipment without compromising the quality of services delivered.

The objective is to establish minimum equipment specification standards for university procurement. A framework for determining equipment standardization was developed, end-users’ need assessments and energy audits were conducted, equipment specifications were formulated, stakeholders were consulted, and equipment policy to ensure energy efficiency and sustainability were suggested.

The electricity consumption was primarily due to air-conditioning (55.3%) and lighting (26.3%). Electricity savings is attained by adopting a higher standards of air conditioning energy efficiency ratio (45%), and changing to light emitting diode for lights (31%) and for monitors (5%). It is recommended that usage profiling be conducted for all the buildings.
Effects of Trailing Edge Alterations on the Performance of a Small-Scale, Low-Solidity Tidal Turbine Blade Designed for Less Energetic Flows
Authors: Encarnacion Job Immanuel , Lavery Gavin , Ordoñez-Sanchez Stephanie , Johnstone Cameron
Published: December 2019

Computer simulations aid in the design of any device. However, physical testing is still needed to validate these simulations and problems may arise if fabrication limits are not incorporated. This study was undertaken to quantify the losses in a low-solidity turbine rotor designed for less energetic flow. The blade was tested at a scale of 1m resulting in a blade length of 219mm. A 0.5mm minimum thickness fabrication limit was worked with by shifting all the points of the upper surface of the blade sections by 0.5mm at the 219mm scale introducing a huge distortion in each of the blade sections. Lift and drag characteristics of the distorted aerofoil are obtained via ANSYS Fluent and served as the corrected inputs for the BEM characterisation. It was found that the BEM predicts a reduced performance similar to the physical testing although it still over predicts the performance of the turbine. However, there is an agreement on the trend of the simulated performance and the physical testing in addition to the reduction of the variation between the two. Additional aerofoil alterations are studied to inform on future experimental designs. It was then found that out of the altered cases, shifting the upper surface by the required minimum thickness resulted in the best approximation of the simulated performance. This is far from acceptable as the variation between the ideal computer simulated case is too large to just incorporate corrections. Thus, an analysis is carried out using a 400mm scaled blade, thereby decreasing the distortion on each blade section. The results of the analysis show good agreement with the ideal section and minimal reduction in performance at about 5% less than the ideal.
A System Analysis of Pressurized Electrolysis for Compressed Hydrogen Production
Authors: Hamilton Ryan T. , McLarty Dustin
Published: December 2019

Renewable production of hydrogen offers a clean and sustainable replacement of fossil fuels. As an energy carrier hydrogen is compressed and stored at high pressures. Pressurized water electrolysis improves plant performance as hydrogen compression is an energy intensive process. This work analyzes hydrogen production over the temperature range of 100°C to 800°C and pressure range of 1 bar to 700 bar. The sensitivity of plant efficiency to hydrogen compression technology and waste heat recovery is investigated. This study reveals that a lower-heating-value electric energy efficiency of 84% can be achieved when pressurized electrolysis avoids the inefficiencies of hydrogen compression. With the availability of high-quality waste heat plant efficiency can reach 98% for a pipeline distribution scenario at 3MPa. When no waste heat is available plant efficiency is independent of electrolysis temperature. For hydrogen use in the transportation sector, pressurized supercritical water electrolysis at 800°C has the potential to improve plant efficiency by 14% from a baseline of non-pressurized electrolysis at 800°C.
Modeling the Thermal Performance of Falling Particle Receivers Subject to External Wind
Authors: Mills Brantley , Shaeffer Reid , Ho Clifford K. , Yue Lindsey
Published: December 2019

Falling particle receivers (FPRs) are an important component of future falling particle concentrating solar power plants to enable next-generation energy generation. High thermal efficiencies in a FPR are required to high thermodynamic efficiencies of the system. External winds can significantly impact the thermal performance of cavity-type FPRs primarily through changing the air flow in and out of the aperture. A numerical parametric study is performed in this paper to quantify the effect of wind on the thermal performance of a FPR. Wind direction was found to be a significant parameter that can affect the receiver thermal efficiency. The particle mass flow rate did not significantly change the overall effect of wind on the receiver. The receiver efficiency was strong function of the particle diameter, but this was primarily a result of varying curtain opacity with different diameters and not from varying effects with wind. Finally, the model was used to demonstrate that receiver efficiencies of 90% were achievable under the assumption that the effect of wind/advective losses were mitigated.
Optical Ray-Tracing Performance Modeling of Quartz Half-Shell Tubes Aperture Cover for Falling Particle Receiver
Authors: Yellowhair Julius , Ho Clifford K.
Published: December 2019

A 1 MWt falling particle receiver prototype was designed, built and is being evaluated at Sandia National Laboratories, National Solar Thermal Test Facility (NSTTF). The current prototype has a 1 m2 aperture facing the north field. The current aperture configuration is susceptible to heat and particle losses through the receiver aperture. Several options are being considered for the next design iteration to reduce the risk of heat and particle losses, in addition to improving the receiver efficiency to target levels of ∼90%. One option is to cover the receiver aperture with a highly durable and transmissive material such as quartz glass. Quartz glass has high transmittance for wavelengths less than 2.5 microns and low transmittance for wavelengths greater than 2.5 microns to help trap the heat inside the receiver.

To evaluate the receiver optical performance, ray-tracing models were set up for several different aperture cover configurations. The falling particle receiver is modeled as a box with a 1 m2 aperture on the north side wall. The box dimensions are 1.57 m wide × 1.77 m tall × 1.67 m deep. The walls are composed of RSLE material modeled as Lambertian surfaces with reflectance of either 0.9 for the pristine condition or 0.5 for soiled walls. The quartz half-shell tubes are 1.46 m long with 105 mm and 110 mm inner and outer diameters, respectively. The half-shell tubes are arranged vertically and slant forward at the top by 30 degrees. Four configurations were considered: concave side of the half-shells facing away from the receiver aperture with (1) no spacing and (2) high spacing between the tubes, and concave side of the half-shells facing the aperture with (3) no spacing and (4) high spacing between the tubes. The particle curtain, in the first modeling approach, is modeled as a diffuse surface with transmittance, reflectance, and absorptance values, which are based on estimates from previous experiments for varying particle flow rates. The incident radiation is from the full NSTTF heliostat field with a single aimpoint at the center of the receiver aperture. The direct incident rays and reflected and scattered rays off the internal receiver surfaces are recorded on the internal walls and particle curtain surfaces as net incident irradiance. The net incident irradiances on the internal walls and particle curtain for the different aperture cover configuration are compared to the baseline configuration. In all cases, just from optical performance alone, the net incident irradiance is reduced from the baseline. However, it is expected that the quartz half-shells will reduce the convective and thermal radiation losses through the aperture. These ray-tracing results will be used as boundary conditions in computational fluid dynamics (CFD) analyses to determine the net receiver efficiency and optimal configuration for the quartz half-shells that minimize heat losses and maximize thermal efficiency.
Numerical Simulation of Wave Energy Converter With Hydrofoil Blades Under Various Wave Conditions
Authors: Lei Jie , Gonzalez Erasmo , Yang Yingchen , Zhang Ying , Xu Ben
Published: December 2019

Ocean wave is a rich source of renewable energy with much higher power density than winds. Various WEC technologies have been proposed or are under development. In this study, we developed a 2-dimensional (2D) model and analyzed the rotational motion of the lift-type rotor’s blade under steady flow and unsteady flow. The numerical model was validated by experiments under steady flow. Fast Fourier Transform (FFT) analysis was performed to identify the major contribution of frequency in terms of vortexes generated in the flow field. A comparative study was also performed by comparing all the cases in terms of energy conversion efficiency under different wave conditions. It turns out that the efficiency of energy conversion has a maximum value in the steady flow, while the efficiency for unsteady flow keeps decreasing, therefore this is highly due to the increased dissipation because of the oscillating. When the flow is oscillating, the rotational speed of the rotor under periodic condition is lower than the rotational velocity with steady flow, and a curve fitting was performed in this study to predict the periodic average rotational speed. We conclude that for oscillating flow a minimum of 1.6% energy conversion efficiency can be expected, but it may vary for the actual ocean waves. It is expected the current 2D simulation results can contribute to the wave energy community, especially when the rotor design and optimization is required.
Decarbonizing Power Generation Through the Use of Hydrogen As a Gas Turbine Fuel
Authors: Welch Michael
Published: December 2019

The power generation industry has a major role to play in reducing global greenhouse gas emissions, and carbon dioxide (CO2) in particular. There are two ways to reduce CO2 emissions from power generation: improved conversion efficiency of fuel into electrical energy, and switching to lower carbon content fuels.

Gas turbine generator sets, whether in open cycle, combined cycle or cogeneration configuration, offer some of the highest efficiencies possible across a wide range of power outputs. With natural gas, the fossil fuel with the lowest carbon content, as the primary fuel, they produce among the lowest CO2 emissions per kWh generated. It is possible though to decarbonize power generation further by using the fuel flexibility of the gas turbine to fully or partially displace natural gas used with hydrogen. As hydrogen is a zero carbon fuel, it offers the opportunity for gas turbines to produce zero carbon electricity. As an energy carrier, hydrogen is an ideal candidate for long-term or seasonal storage of renewable energy, while the gas turbine is an enabler for a zero carbon power generation economy.

Hydrogen, while the most abundant element in the Universe, does not exist in its elemental state in nature, and producing hydrogen is an energy-intensive process. This paper looks at the different methods by which hydrogen can be produced, the impact on CO2 emissions from power generation by using pure hydrogen or hydrogen/natural gas blends, and how the economics of power generation using hydrogen compare with today’s state of the art technologies and carbon capture. This paper also addresses the issues surrounding the combustion of hydrogen in gas turbines, historical experience of gas turbines operating on high hydrogen fuels, and examines future developments to optimize combustion emissions.
Evolution Algorithms and Biomass Properties Prediction: A Review
Authors: Olatunji Obafemi , Akinlabi Stephen , Madushele Nkosinathi , Adedeji Paul , Fatoba Samuel
Published: December 2019

The complexity of real-world applications of biomass energy has increased substantially due to so many competing factors. There is an ongoing discussion on biomass as a renewable energy source and its cumulative impact on the environment vis-a-vis water competition, environmental pollution and so on. This discussion is coming at a time when evolutionary algorithms and its hybrid forms are gaining traction in several applications. In the last decade, evolution algorithms and its hybrid forms have evolved as a significant optimization and prediction technique due to its flexible characteristics and robust behaviour. It is very efficient means of solving complex global optimization problems. This article presents the state-of-the-art review of different types of evolutionary algorithms, which have been applied in the prediction of major properties of biomass such as elemental compositions and heating values. The governing principles, applications, merits, and challenges associated with this technique are elaborated. The future directions of the research on biomass properties prediction are discussed.
Applications of Geothermal Energy in Space Cooling: A Simulator Study of Existing Oil Well to Activate an Absorption Chiller
Authors: Ghaith Fadi A. , Wars Kamal Majlab
Published: December 2019

This paper addresses the potential of integrating the existing oil wells and absorption chiller for the purpose of provision space cooling for the base camp of oil field at Block 9 located in Oman. The wellbore was used as a hot water feed to the chiller. Well S 347 was selected as the hot water source and well S 179 was selected to be the injection well for the outlet water.

The existing wells were assessed via PIPESIM software. Using PIPESIM software, the fluid temperatures, well pressure and flow rates were obtained and analyzed throughout NODAL analyses. The water temperature of 100 °C, well head pressure of 100 psi and flow rate of 30 m3/h, were found to be the optimum operating parameters. The COP of the absorption chiller was obtained via ABSIM software. The variable operating conditions were investigated and elaborated as a function of the efficiency and capacity ratio. The designed system was configured to yield 0.733 COP and a capacity of 377 KW which met the cooling capacity of the admin building of block 9. The entire feasibility analysis was performed in terms of the overall cost as well as the saving that would be achieved from such homogeneity. The payback period of the entire system was found to be 7 years which emphasized a great potential of adapting the technology if the operating resources are available.
Risk Assessment on Working Fluid Selection for Closed-Cycle Gas Turbine Systems
Authors: Osigwe Emmanuel O. , Pilidis Pericles , Nikolaidis Theoklis , Igbong Dodeye
Published: December 2019

From a thermodynamic viewpoint, it is almost possible to utilize all permanent gases as a working fluid for closed-cycle gas turbine energy conversion system. However, this possibility could be limited due to several criteria, some of which are dictated by both technological and economic requirements. This paper provides a risk assessment on possible uncertainties and operational challenges for selected working fluids such as helium, carbon-dioxide, nitrogen and air, which could impact on the closed-cycle gas turbine technology. The risk assessment presented in this paper is described in two parts which include; technological and financial risk. The technological risk gives an assessment on the effect of the selected working fluids on components material technology, turbine entry temperature, and fluid management system while the financial risk aspect gives an assessment in terms of system cost implications influenced by the working fluids and the impact of legislation on investment decision. The overarching discussions from this paper show that helium has an advantage of a possible compact design which could undoubtedly be important cost savings, however, due to government policies on its availability, the operational cost for using helium could make it a huge disadvantage compared with other working fluids discussed in this paper.
Unsteady Simulation on Flow Characteristics of Steam Jet Condensed Into Subcooled Water
Authors: Song Shilin , Chong Daotong , Zhao Quanbin , Chen Weixiong , Yan Junjie
Published: December 2019

Steam jet condensation through sonic nozzle in quiescent subcooled water pool is important for the safety of nuclear reactor system. In this study, the dynamic process of stable condensation jet steam plume is obtained by numerical simulation method. The simulation results are in good agreement with the experimental results. The flow field results indicate that two typical fluctuation regimes exist in the dynamic process of steam plume. Simultaneous analysis of pressure and flow field indicates that two fluctuation regimes produce different pressure pulses. When the detachment phenomenon occurs during the fluctuation of the steam plume, a pressure pulse which value is clearly greater than 220 kPa is generated. When the plume sharply contracts without obvious detachment phenomenon during the fluctuation process, a pressure pulse which value is almost lower than 120 kPa is generated.
Effects of Fission Profiles on the Performance of a U-10Mo Fuel Plate
Authors: Roh Hee Seok , Mohamed Walid , Ozaltun Hakan
Published: December 2019

In order to convert the high-performance research reactors from High Enriched Uranium (HEU) to Low Enriched Uranium (LEU) fuel, U-Mo alloy-based fuels in monolithic form have been proposed. These plate-type fuels consist of a high density and low enriched uranium (LEU) foil coated with a diffusion barrier and encapsulated with the aluminum cladding. The performance of the fuel plate has been evaluated by many studies through experimental tests and numerical analyses. When evaluating the performance of a fuel, it is expensive and time-consuming to consider a variation of several parameters, such as fuel plate geometry, material properties, and operating conditions. Fission profile is a critical component of the fuel performance analysis, causing swelling and creep deformation of the fuel plate. Therefore, it can directly affect the stress and strain distributions over the fuel plate. This study aims at investigating the effect of different fission profiles on the thermo-mechanical performance of the fuel plate by finite element analysis. To investigate the effect of fission profile on fuel performance, several different fission profiles were generated and analyzed. The fission profiles were generated based on actual use.
Ruthenium thin film under methanation atmosphere analyzed by x-ray photoelectron spectroscopy
Authors: Rodriguez-Pereira Jhonatan , Rincón-Ortiz Sergio A. , Quintero-Orozco Jorge H. , García-Castro Andrés C. , Ospina Rogelio
Published: December 2019

Ruthenium thin films were prepared by DC magnetron sputtering on silicon (111) substrates. Samples were subjected to different temperature conditions (300, 400, 500, and 600 °C) under a flow of hydrogen and carbon dioxide with a 4:1 molar ratio to emulate the atmosphere of the methanation reaction. Each treatment was performed in situ. X-ray photoelectron spectroscopy was used to examine the surface chemical changes on Ru thin films before and after the treatments. Survey spectra, Ru 3d, and O 1s core level spectra were measured for each sample. Results showed that the O 1s spectra presented significant changes in all samples; before the thermal treatments, this signal has four different oxygen species, where it can be appreciated the existence of nonstoichiometric oxidized ruthenium. The latter disappears after the first heat treatment due to the high reducibility of ruthenium. Subsequently, in the following treatments, ruthenium oxide reappears, in smaller quantities when compared with the film without treatments. However, the highest amount of oxidized ruthenium can be observed in the temperature range (400–500 °C) during the treatments, in which the conversion of CO2 is maximum for Ru supported catalysts.
Optimization of the response time measuring method for liquid crystal variable retarders
Authors: Campos-Jara Antonio , García Parejo Pilar , Álvarez-Herrero Alberto
Published: December 2019

Liquid crystal variable retarders (LCVRs) have been extensively used as light polarization modulators for ground-based polarimetric applications. Shortly, LCVRs will be used as polarization state analyzers in two instruments onboard the Solar Orbiter mission of the European Space Agency. Both ground- and space-based polarimeters require LCVR response time values that fulfill the required image acquisition rate of the polarimetric measurements. Therefore, it is necessary to have a reliable method to measure the LCVR optical retardance response times. Response times are usually estimated via optical methods using crossed or parallel polarizers. Nevertheless, these methods measure light intensity transitions to infer the response time instead of directly measuring the changes in the optical retardance. In this work, an experimental setup that uses a Soleil-Babinet variable compensator is proposed. On one hand, this allows one to study the effect of the nonlinear dependence of the light intensity on the optical retardance in the response time determination, which is neglected in most works. On the other hand, the use of the variable compensator allows one to measure the LCVR response times in the highest sensitivity areas of the system that minimizes the uncertainty of the measurement. The six transitions for the Polarimetric and Helioseismic Imager instrument modulation scheme of a representative LCVR have been measured. Based on the results, the optimized conditions to measure response times are found, which can be achieved by using the variable compensator and an IR wavelength (λ = 987.7 nm) as proposed in the experimental setup.
A simple method for depth estimation of a sound source at known range in the deep sea
Authors: Lu Yanyang , Yang Kunde , Duan Rui
Published: December 2019

Based on the distribution of acoustic intensity at different depths at a fixed distance, a simple method is proposed to estimate the sound source depth at known range in the deep sea. First, the method calculates the acoustic intensity distribution of all the depths at a receiving distance. Second, the depths with the strongest acoustic intensity are selected. Sound sources are set at the selected depths to calculate the transmission loss (TL) at the same distance through the acoustic model, and the depth of the minimum superimposed TL is considered as the depth of the original sound source. The simulation and experiment verify the feasibility and reliability of the method.
In Vitro
Susceptibility Testing of GSK656 against
Mycobacterium
Species
Authors: Dong Wenzhu , Li Shanshan , Wen Shu’an , Jing Wei , Shi Jin , Ma Yifeng , Huo Fengmin , Gao Fei , Pang Yu , Lu Jie
Published: December 2019

In this study, we aimed to assess the
in vitro
susceptibility to GSK656 among multiple mycobacterial species and to investigate the correlation between leucyl-tRNA synthetase (LeuRS) sequence variations and
in vitro
susceptibility to GSK656 among mycobacterial species. A total of 187 mycobacterial isolates, comprising 105
Mycobacterium tuberculosis
isolates and 82 nontuberculous mycobacteria (NTM) isolates, were randomly selected for the determination of
in vitro
susceptibility.
Interventricular septal diverticulum and rheumatic mitral valve disease identified and managed concurrently in middle age
Authors: Barker Joseph , Zealand Gary , Williams Miles
Published: December 2019

Cardiac diverticula represent an extremely rare but serious cause of cardiac morbidity and mortality. They can result to arrhythmia, sudden cardiac death and ventricular dysfunction but may have no pathological implications. Here is a case of a 60-year-old Maori farmer with both rheumatic mitral valve disease and left ventricular (LV) septal diverticulum. The requirement for mitral valve replacement raised the complex decision of whether to undergo concurrent diverticulum repair. The haemodynamic significance of the diverticulum was impossible to ascertain, although we could not in good conscience leave such a large diverticulum with potential to influence further systolic deterioration. Three months after the procedures, the patient developed severe tricuspid regurgitation which is a first reported association postseptal diverticulum repair. The case highlights that careful consideration is required in repairing LV septal diverticula and an emphasis should be placed on complications and the requirement for repeat surgery during the consent process.