bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative Determination of Phenolic Acids and Flavonoids in Fresh Whole Crop Rice, Silage, and Hay at Different Harvest Periods
Authors: Kuppusamy Palaniselvam , Kim Dahye , Park Hyung Soo , Jung Jeong Sung , Choi Ki Choon
Published: November 2020

Whole crop rice (WCR) is used as an important feed for livestock ruminants. In this study, “Yeongwoo” variety WCR (cultivated on the Korean peninsula) was harvested at three different maturity stages (booting, heading, and milk) and their phenolic acid and flavonoid profiles in the lactic acid bacteria (LAB)-inoculated and noninoculated silage, hay, and fresh freeze-dried WCR extract were quantified. The alterations in the phenolic and flavonoid contents of the selected WCR during maturation in different samples were analyzed by the High-Performance Liquid Chromatography- Diode Array Detector (HPLC–DAD) technique. The six phenolics (caffeic acid, ferulic acid, p-coumaric acid, chlorogenic acid, dihydroxy benzoic acid, and prophyl gallate) and six flavonoids (rutin hydroxide, luteolin, kaempferol, vitexin, myricetin, and quercetin) were noted to have slight differences between the LAB-inoculated and noninoculated silage samples; however, the phenolics and flavonoids were higher in hay WCR at the milk stage compared to the silage and fresh freeze-dried samples. The results indicate that WCR harvest times have different phenolic compounds in the WCR silage, hay, and fresh samples. The phenolic and flavonoid compounds were higher (p < 0.05) with the increase in maturity (Stage 1–3). The stage of WCR maturity was positively related (p < 0.05) to the amount of phenolic acid and flavonoid contents (µg/g) in hay, silage, and fresh freeze-dried extract. We observed the WCR had high amounts of phenolic acid and flavonoid concentrations at milk stage (Stage 3) hay (quercetin, kaemferol, luteolin, ferulic acid, caffeic acid, and coumaric acid were 1.28, 1.29, 0.54, 1.54, 1.92, and 1.81 µg/g, respectively) compared with the booting and heading stages (Stages 1 and 2), with acceptable accuracy on a pilot scale. Based on these results, it could be concluded that LAB (Lactobacillus plantarum)-inoculated whole crop rice silage (WCRS) did not affect the phenolics and flavonoids of secondary plant metabolites in fermented silage. However, phenolics and flavonoids were of higher rations in WCR at the milk stage. Furthermore, this phenolic acid and flavonoid effect needs to be confirmed using large-scale in vivo analysis.
Master and Auxiliary Compound Control for Multi-Channel Confluent Water Supply Switching Control Based on Variable Universe Fuzzy PID
Authors: Zhao Ge , Wang Jian , Li Wei , Zhu Jinsong
Published: November 2020

During the multi-channel confluent water supply process, the pressure control of the main pipe is often held back by such problems as non-linearity, hysteresis and parameter uncertainty, its own unique load dynamic changes, channel switching disturbance and other system characteristics caused by the actual working conditions. Moreover, pressure fluctuations in the main pipe will lead to a reduction in the service life of fire-fighting equipment, an increase in the failure rate, and even an interruption of the fire-fighting water supply. Therefore, a master and auxiliary control strategy is proposed to stabilize the pressure change in the process of multi-channel concentrated water supply switching, by using variable universe fuzzy proportional integral derivative (PID) control as the main controller on the main pipe and traditional PID control as the subsidiary controller on the channel. The control strategy is verified by the co-simulation platforms of LabVIEW and AMESim. Simulation results show that the variable universe fuzzy PID control and the master and auxiliary compound control based on the variable universe fuzzy PID control have advantages in step response, tracking response and anti-interference, respectively. The parameters obtained in the co-simulation are used in the experimental system. The experimental results show that the maximum deviation rate of main pipe pressure can be reduced by about 10% compared with other control methods under different loads. In conclusion, the proposed control strategy has strong anti-interference ability, fast dynamic response speed, high stability and good peak shaving effect.
Magic Wavelengths for Optical-Lattice Based Cs and Rb Active Clocks
Authors: Singh Sukhjit , Jyoti  , Arora Bindiya , Sahoo B. K. , Yu Yan-mei
Published: November 2020

Active clocks could provide better stabilities during initial stages of measurements over passive clocks, in which stabilities become saturated only after long-term measurements. This unique feature of an active clock has led to search for suitable candidates to construct such clocks. The other challenging task of an atomic clock is to reduce its possible systematics. A major part of the optical lattice atomic clocks based on neutral atoms are reduced by trapping atoms at the magic wavelengths of the optical lattice lasers. Keeping this in mind, we find the magic wavelengths between all possible hyperfine levels of the transitions in Rb and Cs atoms that were earlier considered to be suitable for making optical active clocks. To validate the results, we give the static dipole polarizabilities of Rb and Cs atoms using the electric dipole transition amplitudes that are used to evaluate the dynamic dipole polarizabilities and compare them with the available literature values.
On Some Coupled Fixed Points of Generalized T-Contraction Mappings in a bv(s)-Metric Space and Its Application
Authors: George Reny , Mitrović Zoran D. , Radenović Stojan
Published: November 2020

Common coupled fixed point theorems for generalized T-contractions are proved for a pair of mappings S:X×X→X and g:X→X in a bv(s)-metric space, which generalize, extend, and improve some recent results on coupled fixed points. As an application, we prove an existence and uniqueness theorem for the solution of a system of nonlinear integral equations under some weaker conditions and given a convergence criteria for the unique solution, which has been properly verified by using suitable example.
The Anti-Inflammatory Protein TNIP1 Is Intrinsically Disordered with Structural Flexibility Contributed by Its AHD1-UBAN Domain
Authors: Shamilov Rambon , Vinogradova Olga , Aneskievich Brian J.
Published: November 2020

TNFAIP3 interacting protein 1 (TNIP1) interacts with numerous non-related cellular, viral, and bacterial proteins. TNIP1 is also linked with multiple chronic inflammatory disorders on the gene and protein levels, through numerous single-nucleotide polymorphisms and reduced protein amounts. Despite the importance of TNIP1 function, there is limited investigation as to how its conformation may impact its apparent multiple roles. Hub proteins like TNIP1 are often intrinsically disordered proteins. Our initial in silico assessments suggested TNIP1 is natively unstructured, featuring numerous potentials intrinsically disordered regions, including the ABIN homology domain 1-ubiquitin binding domain in ABIN proteins and NEMO (AHD1-UBAN) domain associated with its anti-inflammatory function. Using multiple biophysical approaches, we demonstrate the structural flexibility of full-length TNIP1 and the AHD1-UBAN domain. We present evidence the AHD1-UBAN domain exists primarily as a pre-molten globule with limited secondary structure in solution. Data presented here suggest the previously described coiled-coil conformation of the crystallized UBAN-only region may represent just one of possibly multiple states for the AHD1-UBAN domain in solution. These data also characterize the AHD1-UBAN domain in solution as mostly monomeric with potential to undergo oligomerization under specific environmental conditions (e.g., binding partner availability, pH-dependence). This proposed intrinsic disorder across TNIP1 and within the AHD1-UBAN region is likely to impact TNIP1 function and interaction with its multiple partners.
Surface Modification of Catalysts via Atomic Layer Deposition for Pollutants Elimination
Authors: Wang Xiaofeng , Zhao Zhe , Zhang Chengcheng , Li Qingbo , Liang Xinhua
Published: November 2020

In recent years, atomic layer deposition (ALD) is widely used for surface modification of materials to improve the catalytic performance for removing pollutants, e.g., CO, hydrocarbons, heavy metal ions, and organic pollutants, and much progress has been achieved. In this review, we summarize the recent development of ALD applications in environmental remediation from the perspective of surface modification approaches, including conformal coating, uniform particle deposition, and area-selective deposition. Through the ALD conformal coating, the activity of photocatalysts improved. Uniform particle deposition is used to prepare nanostructured catalysts via ALD for removal of air pollutions and dyes. Area-selective deposition is adopted to cover the specific defects on the surface of materials and synthesize bimetallic catalysts to remove CO and other contaminations. In addition, the design strategy of catalysts and shortcomings of current studies are discussed in each section. At last, this review points out some potential research trends and comes up with a few routes to further improve the performance of catalysts via ALD surface modification and deeper investigate the ALD reaction mechanisms.
Perovskite and Spinel Catalysts for Sulfate Radical-Based Advanced Oxidation of Organic Pollutants in Water and Wastewater Systems
Authors: Manos Donatos , Miserli Kleopatra , Konstantinou Ioannis
Published: November 2020

Since environmental pollution by emerging organic contaminants is one of the most important problems, gaining ground year after year, the development of decontamination technologies of water systems is now imperative. Advanced oxidation processes (AOPs) with the formation of highly reactive radicals can provide attractive technologies for the degradation of organic pollutants in water systems. Among several AOPs that can be applied for the formation of active radicals, this review study focus on sulfate radical based-AOPs (SR-AOPs) through the heterogeneous catalytic activation of persulfate (PS) or peroxymonosulfate (PMS) using perovskite and spinel oxides as catalysts. Perovskites and spinels are currently receiving high attention and being used in substantial applications in the above research area. The widespread use of these materials is based mainly in the possibilities offered by their structure as it is possible to introduce into their structures different metal cations or to partially substitute them, without however destroying their structure. In this way a battery of catalysts with variable catalytic activities can be obtained. Due to the fact that Co ions have been reported to be one of the best activators of PMS, special emphasis has been placed on perovskite/spinel catalysts containing cobalt in their structure for the degradation of organic pollutants through heterogeneous catalysis. Among spinel materials, spinel ferrites (MFe2O4) are the most used catalysts for heterogeneous activation of PMS. Specifically, catalysts with cobalt ion in the A position were reported to be more efficient as PMS activators for the degradation of most organic pollutants compared with other transition metal catalysts. Substituted or immobilized catalysts show high rates of degradation, stability over a wider pH area and also address better the phenomena of secondary contamination by metal leaching, thus an effective method to upgrade catalytic performance.
Use of a Reforming Catalyst for Hydrogen Production in the Carbonization Process of Torrefied Biomass
Authors: Lopez-Urionabarrenechea Alexander , Acha Esther , Adrados Aitziber , Solar Jon , Caballero Blanca María , de Marco Isabel
Published: November 2020

The utilization of charcoal from woody biomass is an efficient way to reduce CO2 emissions from the metallurgical industry. The main aim of this work is to study the charcoal production process from torrefied biomass. For this purpose, torrefaction (3 °C min−1, 250 °C, 30 min) and carbonization (3 °C min−1, 750 °C, 30 min) experiments of eucalyptus wood were carried out in a 3.5 L tank reactor. In the carbonization experiments, a thermo-catalytic treatment of the vaporized phase was also performed, with the objective of producing less condensates and H2-rich gases. The results show that the torrefaction pre-treatment does not affect the chemical properties of charcoal but significantly improves the performance of the carbonization process, where more than 50 wt% of charcoal is obtained. In addition, the thermal and thermo-catalytic treatment of the vaporized phase during the carbonization of torrefied biomass yields better results than in the case of fresh biomass. When torrefied biomass is used as raw material and the reforming catalyst is employed to treat the vapors and gases, a proportion of 71 vol% of H2 in the gases is achieved, together with very low quantities of condensates (8.0 wt%). This allows designing a carbonization process in which, in addition to charcoal, pure H2 can also be produced.
Early Treatment of Interleukin-33 can Attenuate Lupus Development in Young NZB/W F1 Mice
Authors: Mohd Jaya Fatin Nurizzati , Liu Zhongyi , Chan Godfrey Chi-Fung
Published: November 2020

Interleukin-33 (IL-33), a member of the IL-1 cytokine family, has been recently associated with the development of autoimmune diseases, including systemic lupus erythematosus (SLE). IL-33 is an alarmin and a pleiotropic cytokine that affects various types of immune cells via binding to its receptor, ST2. In this study, we determine the impact of intraperitoneal IL-33 treatments in young lupus, NZB/W F1 mice. Mice were treated from the age of 6 to 11 weeks. We then assessed the proteinuria level, renal damage, survival rate, and anti-dsDNA antibodies. The induction of regulatory B (Breg) cells, changes in the level of autoantibodies, and gene expression were also examined. In comparison to the control group, young NZB/W F1 mice administered with IL-33 had a better survival rate as well as reduced proteinuria level and lupus nephritis. IL-33 treatments significantly increased the level of IgM anti-dsDNA antibodies, IL-10 expressing Breg cells, and alternatively-induced M2 macrophage gene signatures. These results imply that IL-33 exhibits a regulatory role during lupus onset via the expansion of protective IgM anti-dsDNA as well as regulatory cells such as Breg cells and M2 macrophages.
A New Modification of Rb[Al(NH2)4] and Condensation in Solid State
Authors: Bäucker Christian , Niewa Rainer
Published: November 2020

A new modification of Rb[Al(NH2)4] in space group C2/c, which differs from the known structural modification in the way the [Al(NH2)4]−-tetrahedra are arranged in the surrounding area of the rubidium cation, was obtained from ammonothermal synthesis at 673 K and 680 bar. The crystal structure was determined by Rietveld refinements and further investigated by infrared and Raman spectroscopy. Thermal gravimetric investigations indicate two decomposition steps up to 450 °C, which can be assigned to ammonia leaving the material while the sample liquefies. During the third and final step, volatile rubidium amide is released, leaving nano-scaled cubic AlN behind. Investigating differently aged samples implies decomposition and condensation of amidoaluminate ions already at ambient temperature, which is supported by refinements of single crystal X-ray diffraction data, revealing lower nitrogen amounts than expected. The observed single crystal also exhibits a significantly smaller volume than the reported structures, further supporting the decomposition–condensation mechanism.
Investigation of the Structural and Luminescent Properties and the Chromium Ion Valence of Li2CaGeO4 Crystals Doped with Cr4+ Ions
Authors: Wang Dongmei , Zhang Xiaowei , Wang Xinyu , Leng Zhuang , Yang Qianqian , Ji Wen , Lin Hai , Zeng Fanming , Li Chun , Su Zhongmin
Published: November 2020

Herein, we report on the growth of Cr4+–Li2CaGeO4 crystals by the flux growth method from the flux of LiCl, as well as on the effect of doping Li2CaGeO4 with Cr4+ ions on the NIR region spectral properties and crystal structure. The results quantified the occupancy of Cr4+ in Ge4+ sites. The emission spectrum presented broad bands in the NIR region, i.e., 1000–1500 nm excited by 980 nm, with maximum peaks at 1200 nm at room temperature caused by the transition of 3T2→3A2 in Cr4+ ions. The lifetime decreased with the Cr4+ ion doping concentration, specifically from 14.038 to 12.224 ms. The chemical composition and the valence state of chromium in Li2CaGeO4 were analyzed using X-ray photoelectron spectroscopy, which showed that the chromium in Li2CaGeO4 was tetravalent and no trivalent chromium was found. Therefore, the Cr4+–Li2CaGeO4 crystal has a great potential and future in optical applications.
Prevalence and Impact of Reported Drug Allergies among Rheumatology Patients
Authors: Chan Shirley Chiu Wai , Yeung Winnie Wan Yin , Wong Jane Chi Yan , Chui Ernest Sing Hong , Lee Matthew Shing Him , Chung Ho Yin , Cheung Tommy Tsang , Lau Chak Sing , Li Philip Hei
Published: November 2020

Background: Drug allergies (DA) are immunologically mediated adverse drug reactions and their manifestations depend on a variety of drug- and patient-specific factors. The dysregulated immune system underpinning rheumatological diseases may also lead to an increase in hypersensitivity reactions, including DA. The higher prevalence of reported DA, especially anti-microbials, also restricts the medication repertoire for these already immunocompromised patients. However, few studies have examined the prevalence and impact of reported DA in this group of patients. Methods: Patients with a diagnosis of rheumatoid arthritis (RA), spondyloarthritis (SpA), or systemic lupus erythematosus (SLE) were recruited from the rheumatology clinics in a tertiary referral hospital between 2018 and 2019. Prevalence and clinical outcomes of reported DA among different rheumatological diseases were calculated and compared to a cohort of hospitalized non-rheumatology patients within the same period. Results: A total of 6081 patients (2541 rheumatology patients: 1286 RA, 759 SpA, and 496 SLE; and 3540 controls) were included. DA was more frequently reported among rheumatology patients compared to controls (23.8% vs. 13.8%, p < 0.01). Antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs) were the two most commonly reported categories of DA with a prevalence of 12.0% and 5.1%, respectively. Reported antibiotics allergies were more frequent in patients with RA (OR = 1.20, 95% CI = 1.02–1.62, p = 0.03) and SLE (OR = 4.69, 95% CI = 3.69–5.95, p < 0.01); and associated with increased infection-related admissions among rheumatology patients (OR = 1.79, 95% CI = 1.09–2.95, p = 0.02). Among the subgroup of patients referred for allergy testing, 85.7% of beta-lactam antibiotic allergy labels were found to be inaccurate and de-labelled after negative drug provocation testing. Conclusion: The prevalence of reported DA was significantly higher in rheumatology patients. Reported antibiotic allergy was associated with increased rate of infection-related admissions. However, the rate of genuine antibiotic allergy was low. Further studies are needed to guide proper assessment of reported DA and impact of comprehensive allergy testing in this group of patients.
A Novel and Simple Exercise Test Parameter to Assess Responsiveness to Cardiac Resynchronization Therapy
Authors: Cozlac Alina-Ramona , Petrescu Lucian , Crisan Simina , Luca Constantin Tudor , Vacarescu Cristina , Streian Caius Glad , Lazar Mihai-Andrei , Gurgu Andra , Dragomir Angela , Goanta Emilia Violeta , Vatasescu Radu , Chahine Kandara Mohamed , Rachieru Ciprian , Cozma Dragos
Published: November 2020

This study assessed the value of heart rate recovery index (HRRI), a new parameter of an exercise test, as the predictor of response to cardiac resynchronization therapy (CRT). Methods: Consecutive patients receiving a CRT device were followed up after implantation and every 6 months. An effort test (ET) was quantified by minimum heart rate/maximum heart rate, as well as acceleration and deceleration times. HRRI was calculated as the ratio between acceleration and deceleration time (AT/DT) and compared to outcome. We used logistic regression to assess the predictive value of HRRI for responders and non-responders to CRT. The area under the curve (AUC) was computed to distinguish between positive and negative outcomes. Results: A total of 109 patients (74 men, mean age 63.3 ± 9.8 years) were analyzed; permanent long-term fusion CRT pacing was possible in 65 patients. Patients were assigned to two groups: responders and non-responders (98/11 patients). During a mean follow-up of 36 months, 545 ETs were performed. HRRI was significantly higher in responders versus non-responders (3.16 ± 2 vs. 1.4 ± 0.5, p < 0.001). The optimal cutoff value for HRRI as a predictor of CRT response was 1.51 (area under the receiver operating characteristic (ROC) curve = 0.844). Responders had significant left-ventricular (LV) reverse remodeling (LV end-diastolic volume = 240 ± 90 mL vs. 217 ± 89 mL, p < 0.001) and higher LV ejection fraction (26 ± 5.8% vs. 35 ± 8.7%, p < 0.001). Conclusions: HRRI computation during routine ET is useful for the evaluation of responsiveness to CRT.
The Carotid Sinus as a Viscometer
Authors: Iskander Andrew , Naftalovich Rotem , Pahlevan Niema M.
Published: November 2020

Our group thought the study by Lee and Kim entitled “Hemodynamic Changes in the Carotid Artery after Infusion of Normal Saline Using Computational Fluid Dynamics” was a very elegant method to discern the changes in blood rheology within the carotid sinus after administration of crystalloid [...]
Cognitive Fatigue Is Associated with Altered Functional Connectivity in Interoceptive and Reward Pathways in Multiple Sclerosis
Authors: Chen Michelle H. , DeLuca John , Genova Helen M. , Yao Bing , Wylie Glenn R.
Published: November 2020

Cognitive fatigue is common and debilitating among persons with multiple sclerosis (pwMS). Neural mechanisms underlying fatigue are not well understood, which results in lack of adequate treatment. The current study examined cognitive fatigue-related functional connectivity among 26 pwMS and 14 demographically matched healthy controls (HCs). Participants underwent functional magnetic resonance imaging (fMRI) scanning while performing a working memory task (n-back), with two conditions: one with higher cognitive load (2-back) to induce fatigue and one with lower cognitive load (0-back) as a control condition. Task-independent residual functional connectivity was assessed, with seeds in brain regions previously implicated in cognitive fatigue (dorsolateral prefrontal cortex (DLPFC), ventromedial prefrontal cortex (vmPFC), dorsal anterior cingulate cortex (dACC), insula, and striatum). Cognitive fatigue was measured using the Visual Analogue Scale of Fatigue (VAS-F). Results indicated that as VAS-F scores increased, HCs showed increased residual functional connectivity between the striatum and the vmPFC (crucial in reward processing) during the 2-back condition compared to the 0-back condition. In contrast, pwMS displayed increased residual functional connectivity from interoceptive hubs—the insula and the dACC—to the striatum. In conclusion, pwMS showed a hyperconnectivity within the interoceptive network and disconnection within the reward circuitry when experiencing cognitive fatigue.
Pawpaw (Carica papaya) Peel Waste as a Novel Green Heterogeneous Catalyst for Moringa Oil Methyl Esters Synthesis: Process Optimization and Kinetic Study
Authors: Oladipo Babatunde , Ojumu Tunde V , Latinwo Lekan M , Betiku Eriola
Published: November 2020

This study evaluated pawpaw (Carica papaya) peel ash as a green solid base catalyst for Moringa oleifera oil methyl esters (MOOME) production. Taguchi orthogonal array approach was used to examine the impact of vital process input variables (calcined pawpaw peel (CPP) loading, reaction temperature, methanol-to-M. oleifera oil (MeOH:MOO) molar ratio and reaction time) on the MOOME yield. Catalytic potency potential of the CPP was evaluated by Fourier transform infrared (FTIR), Barrett-Joyner-Halenda (BJH), Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) methods. The results obtained indicate that the CPP consists of nanoparticles and alkaline elements K (23.89 wt.%), Ca (2.86 wt.%) and Mg (1.00 wt.%). The high values of coefficient of determination, R2 (0.9992) and adjusted R2 (0.9968) as well as the low value of the coefficient of variation (0.31%) for the model developed indicate it can be used to sufficiently describe the transesterification process. MOOME yield of 96.43 ± 0.10 wt.% was achieved at the optimum values of 3.5 wt.% CPP loading, 9:1 MeOH:MOO molar ratio, 35 °C reaction temperature and 40 min reaction time. The kinetic modeling of the transesterification process determined the reaction rate constant and overall reaction order as 0.20465 L·mol−1·s−1 and 2, respectively. The results of this study demonstrate both CPP and MOO are feasible renewable resources for MOOME production. The kinetic data generated may be useful in reactor design for the transesterification process.
Catchment Based Aerodynamic Performance Analysis of Small Wind Turbine Using a Single Blade Concept for a Low Cost of Energy
Authors: Kelele Hailay Kiros , Nielsen Torbjørn Kirstian , Froyd Lars , Bayray Kahsay Mulu
Published: November 2020

For low and medium wind conditions, there is a possibility to harness maximum wind potential reducing the cost of energy by employing catchment-based wind turbine designs. This paper aims to study catchment-based small wind turbine aerodynamic performance for improved efficiency and reduced cost of energy. Hence, design parameters are considered based on specific conditions within a catchment area. The bins and statistical methods implemented with Weibull distribution of wind data for selected sites to characterize the wind conditions and a weighted average method proposed to create representative wind conditions implementing a single blade concept. The blade element method was applied using Matlab code (version R2017a, MathWorks Inc., Natick, MA, US) for aerodynamic design and analysis, and computational fluid dynamics employed using ANSYS—Fluent (version 18.1, ANSYS Inc., Canonsburg, PA, USA) for validation. The performance of the designed blade is evaluated based on annual energy production, capacity factor and power coefficient. Then, for site-specific wind conditions, yearly energy production, and relative cost of energy are examined against rated power. Appropriate rated power for a low cost of energy identified and performance measures evaluated for each site. As a result, a maximum power coefficient of around 51.8% achieved at a design wind speed of 10 m/s, and higher capacity factors of 28% and 50.9% respectively attained for the low and high wind conditions at the proposed rated powers. Therefore, for different wind condition sites, enhanced performance at a low cost of energy could be achieved using a single blade concept at properly selected rated powers employing suitable design conditions and procedures.
Event Effects Estimation on Electricity Demand Forecasting
Authors: Hirose Kei , Wada Keigo , Hori Maiya , Taniguchi Rin-ichiro
Published: November 2020

We consider the problem of short-term electricity demand forecasting in a small-scale area. Electric power usage depends heavily on irregular daily events. Event information must be incorporated into the forecasting model to obtain high forecast accuracy. The electricity fluctuation due to daily events is considered to be a basis function of time period in a regression model. We present several basis functions that extract the characteristics of the event effect. When the basis function cannot be specified, we employ the fused lasso for automatic construction of the basis function. With the fused lasso, some coefficients of neighboring time periods take exactly the same values, leading to stable basis function estimation and enhancement of interpretation. Our proposed method is applied to the electricity demand data of a research facility in Japan. The results show that our proposed model yields better forecast accuracy than a model that omits event information; our proposed method resulted in roughly 12% and 20% improvements in mean absolute percentage error and root mean squared error, respectively.
Hydrogen Fuel Cell Road Vehicles: State of the Art and Perspectives
Authors: Bethoux Olivier
Published: November 2020

Driven by a small number of niche markets and several decades of application research, fuel cell systems (FCS) are gradually reaching maturity, to the point where many players are questioning the interest and intensity of its deployment in the transport sector in general. This article aims to shed light on this debate from the road transport perspective. It focuses on the description of the fuel cell vehicle (FCV) in order to understand its assets, limitations and current paths of progress. These vehicles are basically hybrid systems combining a fuel cell and a lithium-ion battery, and different architectures are emerging among manufacturers, who adopt very different levels of hybridization. The main opportunity of Fuel Cell Vehicles is clearly their design versatility based on the decoupling of the choice of the number of Fuel Cell modules and hydrogen tanks. This enables manufacturers to meet various specifications using standard products. Upcoming developments will be in line with the crucial advantage of Fuel Cell Vehicles: intensive use in terms of driving range and load capacity. Over the next few decades, long-distance heavy-duty vehicles and fleets of taxis or delivery vehicles will develop based on range extender or mild hybrid architectures and enable the hydrogen sector to mature the technology from niche markets to a large-scale market.
Analysis and Design Guidelines for Current Control Loops of Grid-Connected Converters Based on Mathematical Models
Authors: Abad Gonzalo , Sanchez-Ruiz Alain , Valera-García Juan José , Milikua Aritz
Published: November 2020

Having a method for analyzing and designing regulators of controls that contain many current loops such as active filters is not a trivial task. There can be many parameters of regulators and filters that must be carefully selected in order to fulfill certain desired requirements. For instance, these can be stability, dynamic response, robustness under uncertainty of parameters, and rejection capability to switching harmonics. Hence, this paper provides general analysis guidelines for designing current control loops by using mathematical models in an αβ reference frame. Then, by using the proposed modeling tool, a multi-objective tuning algorithm is proposed that helps obtain all the control loops’ regulator and filter parameters, meeting all the desired requirements. Thus, the proposed analysis and design methodology is illustrated by applying it to three different controls conceived in a dq rotating reference frame with PI (Proportional Integral) regulators. The first control presents two current loops (simple dq current control), the second control uses four current loops (dual vector control, for unbalanced loads), while the third control presents eight current loops (active filter controlling current harmonics). Several experimental and simulation results show the effectiveness and usefulness of the proposed method. Since the mathematical model employed is in the αβ reference frame, it can also be easily applied to controls conceived in a αβ reference frame using resonant regulators, providing also a common comparative framework.
Approximation Algorithm-Based Prosumer Scheduling for Microgrids
Authors: Shin Incheol
Published: November 2020

Since the inherent intermittency and uncertainty of renewable energy resources complicates efficient Microgrid operations, a Demand Response (DR) scheme is implemented for customers in the grid to alter their power-usage patterns. However, for a real-time pricing model at the current DR, the automated decision on the energy price is not trustworthy because of artificial interferences to the power generation. As opposed to energy price, an operational cost-based prosumer scheduling approach would be able to protect the integrity of the power grid operations from deceptive market transactions and assist in robust energy management. To investigate the operational challenges associated with the costs and prosumers in the Microgrid, we focus on formulating the problem mathematically and designing approximation algorithms to solve the problem of how to optimally identify suppliers to minimize the total operational costs associated with providing electricity. We prove the hardness of the scheduling as one of the NP-Hard problems and propose polynomial time algorithms for approximating optimal solutions. With a proper resilience level for reliable power services, the scheduling algorithms include ways to construct not only robust supplier networks, but also group energy communities in terms of black start while minimizing the operational costs. A series of theoretical performances and experimental evaluations also demonstrates the practical effectiveness of this scheduling model for the operations.
Recent Advances in Thermochemical Energy Storage via Solid–Gas Reversible Reactions at High Temperature
Authors: André Laurie , Abanades Stéphane
Published: November 2020

The exploitation of solar energy, an unlimited and renewable energy resource, is of prime interest to support the replacement of fossil fuels by renewable energy alternatives. Solar energy can be used via concentrated solar power (CSP) combined with thermochemical energy storage (TCES) for the conversion and storage of concentrated solar energy via reversible solid–gas reactions, thus enabling round the clock operation and continuous production. Research is on-going on efficient and economically attractive TCES systems at high temperatures with long-term durability and performance stability. Indeed, the cycling stability with reduced or no loss in capacity over many cycles of heat charge and discharge of the material is pursued. The main thermochemical systems currently investigated are encompassing metal oxide redox pairs (MOx/MOx−1), non-stoichiometric perovskites (ABO3/ABO3−δ), alkaline earth metal carbonates and hydroxides (MCO3/MO, M(OH)2/MO with M = Ca, Sr, Ba). The metal oxides/perovskites can operate in open loop with air as the heat transfer fluid, while carbonates and hydroxides generally require closed loop operation with storage of the fluid (H2O or CO2). Alternative sources of natural components are also attracting interest, such as abundant and low-cost ore minerals or recycling waste. For example, limestone and dolomite are being studied to provide for one of the most promising systems, CaCO3/CaO. Systems based on hydroxides are also progressing, although most of the recent works focused on Ca(OH)2/CaO. Mixed metal oxides and perovskites are also largely developed and attractive materials, thanks to the possible tuning of both their operating temperature and energy storage capacity. The shape of the material and its stabilization are critical to adapt the material for their integration in reactors, such as packed bed and fluidized bed reactors, and assure a smooth transition for commercial use and development. The recent advances in TCES systems since 2016 are reviewed, and their integration in solar processes for continuous operation is particularly emphasized.
Common Language of Sustainability for Built Environment Professionals—The Quintuple Helix Model for Higher Education
Authors: Crilly Michael , Vemury Chandra Mouli , Humphrey Richard , Rodriguez Sergio , Crosbie Tracey , Johnson Karen , Wilson Alexander , Heidrich Oliver
Published: November 2020

One of the repeating themes around the provision of the knowledge and skills needed for delivering sustainable communities is the idea of a “common language” for all built environment professionals. This suggestion has been repeated regularly with each new political and professional review within and between different sectors responsible for the delivery of sustainable communities. There have been multiple efforts to address academic limitations, industry fragmentation and promote more interdisciplinary working and sector collaboration. This research explored the role of skills for sustainable communities, particularly within the higher education (HE) sector, and the responses to support the development of a “common language of sustainability” that can be shared between different sectors, professional disciplines and stakeholders. As an interdisciplinary group of academics and practitioners working with the HE sector in the North East of England, we evaluate the progression of sector collaboration to develop a quintuple helix model for HE. We use this as a suitable framework for systematically “mapping” out the mixed sector (academic, public, business, community and environmental organisations) inputs and influences into a representative sample of HE degree modules that are delivered from foundation and undergraduate to postgraduate levels, including examples of part-time and distance-learning modules. We developed a cascade of models which demonstrate increasing levels of collaboration and their potential positive impact on the effectiveness of education on sustainable communities. The methodological assessments of modules were followed by semi-structured group reflective analysis undertaken through a series of online workshops (recorded during the Covid19 lockdown) to set out a collective understanding of the generic skills needed for the delivery of sustainable communities. These generic skills for sustainable communities are presented as a pedagogical progression model of teaching activities and learning outcomes applied to the levels within HE. We propose sustainability education principles and progressions with the hope that they can have an impact on the design or review of current degree modules and programmes. The paper informs future sustainability research to be grounded in holism and systems thinking; better understanding of values, ethics, influencing and political impact; and procedural authenticity.
Characteristics of Changes in Particle Size and Zeta Potential of the Digestate Fraction from the Municipal Waste Biogas Plant Treated with the Use of Chemical Coagulation/Precipitation Processes
Authors: Urbanowska Agnieszka , Polowczyk Izabela , Kabsch-Korbutowicz Małgorzata , Seruga Przemysław
Published: November 2020

The organic fraction of waste is increasingly used for biogas production. However, the fermentation process used for this purpose also produces waste in the form of digestate in addition to biogas. Its liquid fraction can, among other things, be a source of water, but its recovery requires many advanced technological processes. Among the first in the treatment train is usually coagulation/chemical precipitation. Its application changes properties, including the size and zeta potential (ζ) of the fractions that have to be removed in subsequent processes. Changes in particle size distribution and ζ potential occurring in the liquid fraction of municipal waste biogas plant digestate and solutions after coagulation/chemical precipitation with FeCl₃·6H₂O, PIX 112 and CaO were analyzed. The particle size distribution of the raw digestate was wide (0.4–300 µm; up to 900 µm without ultrasound). The median particle diameter was about 12 µm. The ζ potential ranged from −25 to −35 mV in the pH range 5–12, and the isoelectric point (IEP) was at pH 2. The best treatment results obtained with the use of. 10 g FeCl₃∙6H₂O/dm³ shifted particle size distribution towards finer particles (median diameter: 8 and 6 µm, respectively, before and after ultrasound). The ζ potential decreased by about 5–10 mV in the pH range 2.5–12 without changing IEP. An amount of 20 g/dm³ of FeCl₃∙6H₂O caused the disappearance of the finest and largest fraction. d50 was about 21.5 µm (17.3 µm after ultrasound). An amount of 20 g/dm³ of FeCl₃∙6H₂O generated a positive high electrokinetic potential in the range of pH 1.8–5. The IEP appeared at pH 8, and after reaching about −5 mV it again became positive at pH about 11.
Numerical Simulation and Experimental Validation of an Oil Free Scroll Compressor
Authors: Cardone Massimo , Gargiulo Bonaventura
Published: November 2020

This paper presents a virtual model of a scroll compressor developed on the one-dimensional analysis software Simcenter Amesim®. The model is semi-empirical: it needs some physical details of the modelled machine (e.g., the cubic capacity), but, on the other hand, it does not require the geometrical features of the spirals, so it needs experimental data to calibrate it. The model also requires rotational speed and the outlet temperature as boundary conditions. The model predicts the power consumption and the mass flow rate and considers leakages and mechanical losses. After the model presentation, this paper describes the test bench and the obtained data used to calibrate and validate the model. At last, the calibration process is described, and the results are discussed. The calculated values fit the experimental data also in extrapolation, despite the model is simple and performs calculations within 7 s. Due to these characteristics, the model is suitable for being used in a larger model as a sub-component.
CFD Analysis on the Balancing Hole Design for Magnetic Drive Centrifugal Pumps
Authors: Kim Won-Sik , Yun Jeong-Eui
Published: November 2020

Balancing holes in single-suction centrifugal pumps are generally applied to attenuate the axial thrust caused by a pressure difference between the front side of a shroud and the rear side of a hub of an impeller. The magnetic drive pump, the subject of this study, has a leak-free airtight structure and an integrated structure of the impeller and inner magnet. To prevent the performance degradation of the magnetic drive caused by heat during operation, complex cooling flow paths connected to balancing holes have been designed so that a sufficient amount of coolant would flow around the magnetic drive. Due to this spatial characteristic, when balancing holes are applied to a magnetic drive pump, the balancing hole flow path becomes very long compared to that of balancing holes applied to conventional pumps. When the balancing hole flow path is long, the flow path loss increases, which in turn increases the adverse effect of balancing holes on the pump performance. Therefore, the design of highly efficient balancing holes to which a sufficient amount of coolant can be supplied is critical in a magnetic drive pump. To this end, two types of balancing holes were investigated in this study. First, balancing holes are drilled in the impeller that rotates during operation. Second, balancing holes are drilled in the inner shaft installed to maintain the centre of rotation of the impeller during pump operation. The results confirmed the flow characteristics of the two types of balancing holes and verified the effect of each balancing hole on the pump performance. Finally, this study found that drilling balancing holes in the shaft were appropriate for the magnetic drive pump, and this type can maintain relatively high efficiency and supply a sufficient amount of coolant to maintain the efficiency of the magnetic drive.
Adaptive Processing for EM Telemetry Signal Recovery: Field Data from Sichuan Province
Authors: Fayemi Olalekan , Di Qingyun , Zhen Qihui , Wang Yu L.
Published: November 2020

This paper deals with the study of multi-channel adaptive noise cancellation with a focus on its application in electromagnetic (EM) telemetry. We presented new variable step-size least mean square (LMS) techniques: regularized variable step-size LMS and regularized sigmoid variable size LMS, for electromagnetic telemetry data processing. Considering the complexity and spatial distribution of environmental noise, algorithms with multiple reference signals were used to retrieve transmitted EM signals. The feasibility of the regularized variable step size LMS algorithms with numerical simulation was analyzed and presented. The adaptive processing techniques were applied in the recovery of frequency and binary phase shift key modulated signal. The proposed multi-channel adaptive technique achieves fast convergence speed, low mean squared error and is shown to have good convergence characteristics compared to conventional methods. In addition to attaining good results from the multi-channel adaptive filter and performing the signal analysis in real-time, we implemented combined fast effective impulse noise removal techniques. The combination of median and mean filters was effective in removing a wide range of impulsive noises without distorting any other data points. Further, electromagnetic telemetry data were acquired during a drilling operation in Sichuan province, China, for real field application. Data processing workflow was designed for EM telemetry data processing based on the noise characteristics, simulation results and expected result for demodulation. To establish a comprehensive overview, a performance comparison of the acquisition array system is also provided. Conclusively, the introduced multichannel adaptive noise canceling techniques are very effective in recovering transmitted EM telemetry signals.
Assessment and Prediction of Air Entrainment and Geyser Formation in a Bottom Outlet: Field Observations and CFD Simulation
Authors: Yang James , Teng Penghua , Nan Junhu , Li Shicheng , Ansell Anders
Published: November 2020

Air entrainment at the intake of a bottom outlet often gives rise to air pockets in its conduit and formation of geysers. The outlet in question comprises a bulkhead gate, gate shaft, horizontal conduit, and exit. Operations show that it suffers from appreciable flow fluctuations and blowouts in the tailwater, which leads to gate operation restrictions. For the purpose of understanding the hydraulic phenomenon, both prototype discharge tests and three-dimensional computational fluid dynamics (CFD) modeling of two-phase flows are performed. The operational focus of the facility are small and large gate openings. The CFD results reveal that, with air entrained in the gate shaft, continual breakup and coalescence of air bubbles in the conduit typify the flow. At small openings below 1 meter, the air–water flow is characterized by either distinct blowouts of regular frequency or continuous air release. In terms of geyser behaviors inclusive of frequency, the agreement is good between field and numerical studies. At large openings, the gate becomes fully submerged, and the flow is discharged without air entrainment and blowouts. The paper showcases the air–water flow features in a typical bottom outlet layout in Sweden, which is intended to serve as an illustration of the study procedure for other similar outlets.