bluuebunny/crossref_metadata_2025 huggingface dataset:
A Multidimensional Multiplexing Mode-Locked Laser Based on a Dual-Ring Integrative Structure for Tri-Comb Generation
Authors: Yang Ruitao , Sun Hao , Lv Haisu , Xu Jian , Wu Jinxuan , Hu Pengcheng , Fu Haijin , Yang Hongxing , Tan Jiubin
Published: November 2020

The tri-comb-based multi-heterodyne detection technique has been proven to be a powerful tool for precision metrology, e.g., laser ranging and spectroscopy. However, in existing tri-comb generation methods, it is difficult to provide a large and variable difference in tri-comb repetition rates. In this paper; we propose a multidimensional multiplexing mode-locked laser based on a dual-ring integrative structure. Combining the dimensions of sub-ring multiplexing and wavelength multiplexing, two modes of tri-comb generation can be achieved with the dual-ring single cavity laser. The generated combs are identified based on the relative intensity of the pulse trains and optical spectrum, and the repetition rates of dual-combs from the same sub-ring are distinguished based on dispersion analysis. With repetition rates of approximately 47 MHz and 49.6 MHz, the minimum and maximum repetition rate difference of the generated tri-comb can be changed from 2.38 kHz and 2.59526 MHz to 2.74 kHz and 2.59720 MHz merely by switching the operation mode of the dual-ring integrated mode-locked laser. The obtained results indicate that our method can offer a powerful scheme for future multi-comb generation and its application in multi-heterodyne detection-based laser ranging and spectroscopy.
Efficient Mercury Removal at Ultralow Metal Concentrations by Cysteine Functionalized Carbon-Coated Magnetite
Authors: Srikhaow Assadawoot , Butburee Teera , Pon-On Weeraphat , Srikhirin Toemsak , Uraisin Kanchana , Suttiponpanit Komkrit , Chaveanghong Suwilai , Smith Siwaporn Meejoo
Published: November 2020

This work reports the preparation and utility of cysteine-functionalized carbon-coated Fe3O4 materials (Cys-C@Fe3O4) as efficient sorbents for remediation of Hg(II)-contaminated water. Efficient removal (90%) of Hg(II) from 1000 ppb aqueous solutions is possible, at very low Cys-C@Fe3O4 sorbent loadings (0.01 g sorbent per liter of Hg(II) solution). At low metal concentrations (5–100 ppb Hg(II)), where adsorption is typically slow, Hg(II) removal efficiencies of 94–99.4% were achievable, resulting in final Hg(II) levels of <1.0 ppb. From adsorption isotherms, the Hg(II) adsorption capacity for Cys-C@Fe3O4 is 94.33 mg g−1, around three times that of carbon-coated Fe3O4 material. The highest partition coefficient (PC) of 2312.5 mgg−1µM−1 was achieved at the initial Hg (II) concentration of 100 ppb, while significantly high PC values of 300 mgg−1µM−1 and above were also obtained in the ultralow concentration range (≤20 ppb). Cys-C@Fe3O4 exhibits excellent selectivity for Hg(II) when tested in the presence of Pb(II), Ni(II), and Cu(II) ions, is easily separable from aqueous media by application of an external magnet, and can be regenerated for three subsequent uses without compromising Hg(II) uptake. Derived from commercially available raw materials, it is highly possible to achieve large-scale production of the functional sorbent for practical applications.
The Impact of Data Filtration on the Accuracy of Multiple Time-Domain Forecasting for Photovoltaic Power Plants Generation
Authors: Eroshenko Stanislav A. , Khalyasmaa Alexandra I. , Snegirev Denis A. , Dubailova Valeria V. , Romanov Alexey M. , Butusov Denis N.
Published: November 2020

The paper reports the forecasting model for multiple time-domain photovoltaic power plants, developed in response to the necessity of bad weather days’ accurate and robust power generation forecasting. We provide a brief description of the piloted short-term forecasting system and place under close scrutiny the main sources of photovoltaic power plants’ generation forecasting errors. The effectiveness of the empirical approach versus unsupervised learning was investigated in application to source data filtration in order to improve the power generation forecasting accuracy for unstable weather conditions. The k-nearest neighbors’ methodology was justified to be optimal for initial data filtration, based on the clusterization results, associated with peculiar weather and seasonal conditions. The photovoltaic power plants’ forecasting accuracy improvement was further investigated for a one hour-ahead time-domain. It was proved that operational forecasting could be implemented based on the results of short-term day-ahead forecast mismatches predictions, which form the basis for multiple time-domain integrated forecasting tools. After a comparison of multiple time series forecasting approaches, operational forecasting was realized based on the second-order autoregression function and applied to short-term forecasting errors with the resulting accuracy of 87%. In the concluding part of the article the authors from the points of view of computational efficiency and scalability proposed the hardware system composition.
Focal Muscle Vibration for Stroke Rehabilitation: A Review of Vibration Parameters and Protocols
Authors: Wang Hongwu , Chandrashekhar Raghuveer , Rippetoe Josiah , Ghazi Mustafa
Published: November 2020

In this review, we present a narrative synthesis of studies on the use of focal muscle vibration (FMV) in stroke rehabilitation with a focus on vibration device, parameters, and protocols. A search was conducted via PubMed, SCOPUS, PEDro, REHABDATA, and Web of Science using the keywords “stroke and focal vibration” or “focal muscle vibration”. Inclusion and exclusion criteria to select the articles were determined. Twenty-two articles involving FMV and stroke were included in this review. Eight different vibration devices were used in the 19 articles that reported the vibration apparatuses. The vibration frequencies ranged from 30 Hz to 300 Hz with amplitudes ranging from 0.01 mm to 2 mm. The vibration treatment frequency ranged from a single treatment to 5 days/week. The session duration ranged from 14 s to 60 min/session with a duration of a single treatment to eight weeks. Twenty different muscles were targeted with 37 different outcome measures used to assess the effects of FMV. The clinical applications of FMV were not confirmed based on available evidence. More research is needed to improve the FMV technology, guide the selection of vibration parameters, optimize the vibration dosage, and develop standardized protocols for FMV therapy in patients with stroke.
Speckle Noise Reduction in Digital Holography Using a DMD and Multi-Hologram Resampling
Authors: Restrepo John , Correa-Rojas Nelson , Herrera-Ramirez Jorge
Published: November 2020

Speckle noise is a well-documented problem on coherent imaging techniques like Digital Holography. A method to reduce the speckle noise level is presented, based on introducing a Digital Micromirror Device to phase modulate the illumination over the object. Multiple holograms with varying illuminations are recorded and the reconstructed intensities are averaged to obtain a final improved image. A simple numerical resampling scheme is proposed to further improve noise reduction. The obtained results demonstrate the effectiveness of the hybrid approach.
Strain Rate Dependent Behavior of Vinyl Nitrile Helmet Foam in Compression and Combined Compression and Shear
Authors: Bailly Nicolas , Petit Yvan , Desrosier Jean-Michel , Laperriere Olivier , Langlois Simon , Wagnac Eric
Published: November 2020

Vinyl nitrile foams are polymeric closed-cell foam commonly used for energy absorption in helmets. However, their impact behavior has never been described in isolation. This study aims to characterize the strain rate dependent behavior of three VN foams in compression and combined compression and shear. Vinyl nitrile samples of density 97.5, 125, and 183 kg/m3 were submitted to quasi-static compression (0.01 s−1) and impacts in compression and combined compression and shear (loading direction of 45°). For impacts, a drop test rig was used, and a method was developed to account for strain rate variation during impactor deceleration. Young’s modulus and stress at plateau were correlated with foam density in both compression and combined loading. Vinyl nitrile foams were strain rate dependent: The absorbed energy at the onset of densification was two to four times higher at 100 s−1 than at 0.01 s−1. In combined loading, the compressive stress at yield was reduced by 43% at a high strain rate. Compared to expanded polypropylene, vinyl nitrile foams transmitted less stress at the onset of densification for equivalent absorbed energy and presented a larger ratio between the compression and shear stresses in combined loading (0.37 at yield). This larger ratio between the compression and shear stresses might explain why vinyl nitrile helmet liners are thought to be better at reducing head rotational acceleration than expanded polypropylene helmet liners.
A MBSE Application to Controllers of Autonomous Underwater Vehicles Based on Model-Driven Architecture Concepts
Authors: Hien Ngo Van , He Ngo Van , Truong Van-Thuan , Bui Ngoc-Tam
Published: November 2020

In this paper, a hybrid realization model is proposed for the controllers of autonomous underwater vehicles (AUVs). This model is based on the model-based systems engineering (MBSE) methodology, in combination with the model-driven architecture (MDA), the real-time unified modeling language (UML)/systems modeling language (SysML), the extended/unscented Kalman filter (EKF/UKF) algorithms, and hybrid automata, and it can be reused for designing controllers of various AUV types. The dynamic model and control structure of AUVs were combined with the specialization of MDA concepts as follows. The computation-independent model (CIM) was specified by the use-case model combined with the EKF/UKF algorithms and hybrid automata to intensively gather the control requirements. Then, the platform-independent model (PIM) was specialized using the real-time UML/SysML to design the capsule collaboration of control and its connections. The detailed PIM was subsequently converted into the platform-specific model (PSM) using open-source platforms to promptly realize the AUV controller. On the basis of the proposed hybrid model, a planar trajectory-tracking controller, which allows a miniature torpedo-shaped AUV to autonomously track the desired planar trajectory, was implemented and evaluated, and shown to have good feasibility.
Effect of Surface Treatment and Storage Time on Immediate Repair Bond Strength Durability of Methacrylate- and Ormocer-Based Bulk Fill Resin Composites
Authors: El-Askary Farid S. , Botros Sara A. , Özcan Mutlu
Published: November 2020

The aim of this study was to evaluate the effect of surface treatment and storage time on immediate repair bond durability of methacrylate- and ormocer-based bulk fill composites. In total, 265 discs were divided into 32 groups (n = 8/group) according to: (1) Material: X-tra fil and Admira Fusion X-tra; (2) Surface treatment: oxygen inhibition; matrix; Futurabond M+; Silane/Futurabond M+; Admira Bond; Silane/Admira Bond; ceramic repair system; and Silane/Cimara bond; and (3) Storage time: 24 h and 6 months. Each disc received three micro-cylinders from the same material. Specimens were subjected to micro-shear bond strength testing either at 24 h or 6 months. Data were analyzed using ANOVA/Tukey’s test/Student t-test (p = 0.05). All experimental factors had significant effect on bond strength (p < 0.0001). Drop in bond strength was noticed in both materials after six months (p < 0.05), except for Admira Fusion X-tra treated with silane/cimara adhesive (p = 0.860). Both materials showed insignificant values with Admira bond either at 24 h or 6 months (p = 0.275 and p = 0.060, respectively). For other treatments, X-tra fil showed significantly higher values at 24 h and 6 months (p < 0.05). Ceramic repair system can be used to immediately repair both methacrylate- and ormocer-based composites.
PP2A-B55 Holoenzyme Regulation and Cancer
Authors: Goguet-Rubio Perrine , Amin Priya , Awal Sushil , Vigneron Suzanne , Charrasse Sophie , Mechali Francisca , Labbé Jean Claude , Lorca Thierry , Castro Anna
Published: November 2020

Protein phosphorylation is a post-translational modification essential for the control of the activity of most enzymes in the cell. This protein modification results from a fine-tuned balance between kinases and phosphatases. PP2A is one of the major serine/threonine phosphatases that is involved in the control of a myriad of different signaling cascades. This enzyme, often misregulated in cancer, is considered a tumor suppressor. In this review, we will focus on PP2A-B55, a particular holoenzyme of the family of the PP2A phosphatases whose specific role in cancer development and progression has only recently been highlighted. The discovery of the Greatwall (Gwl)/Arpp19-ENSA cascade, a new pathway specifically controlling PP2A-B55 activity, has been shown to be frequently altered in cancer. Herein, we will review the current knowledge about the mechanisms controlling the formation and the regulation of the activity of this phosphatase and its misregulation in cancer.
Validation of Omega Subunit of RNA Polymerase as a Functional Entity
Authors: Patel Unnatiben Rajeshbhai , Gautam Sudhanshu , Chatterji Dipankar
Published: November 2020

The bacterial RNA polymerase (RNAP) is a multi-subunit protein complex (α2ββ’ω σ) containing the smallest subunit, ω. Although identified early in RNAP research, its function remained ambiguous and shrouded with controversy for a considerable period. It was shown before that the protein has a structural role in maintaining the conformation of the largest subunit, β’, and its recruitment in the enzyme assembly. Despite evolutionary conservation of ω and its role in the assembly of RNAP, E. coli mutants lacking rpoZ (codes for ω) are viable due to the association of the global chaperone protein GroEL with RNAP. To get a better insight into the structure and functional role of ω during transcription, several dominant lethal mutants of ω were isolated. The mutants showed higher binding affinity compared to that of native ω to the α2ββ’ subassembly. We observed that the interaction between α2ββ’ and these lethal mutants is driven by mostly favorable enthalpy and a small but unfavorable negative entropy term. However, during the isolation of these mutants we isolated a silent mutant serendipitously, which showed a lethal phenotype. Silent mutant of a given protein is defined as a protein having the same sequence of amino acids as that of wild type but having mutation in the gene with alteration in base sequence from more frequent code to less frequent one due to codon degeneracy. Eventually, many silent mutants were generated to understand the role of rare codons at various positions in rpoZ. We observed that the dominant lethal mutants of ω having either point mutation or silent in nature are more structured in comparison to the native ω. However, the silent code’s position in the reading frame of rpoZ plays a role in the structural alteration of the translated protein. This structural alteration in ω makes it more rigid, which affects the plasticity of the interacting domain formed by ω and α2ββ’. Here, we attempted to describe how the conformational flexibility of the ω helps in maintaining the plasticity of the active site of RNA polymerase. The dominant lethal mutant of ω has a suppressor mapped near the catalytic center of the β’ subunit, and it is the same for both types of mutants.
Enhanced Seismic Retrofit of a Reinforced Concrete Building of Architectural Interest
Authors: Terenzi Gloria , Fuso Elena , Sorace Stefano , Costoli Iacopo
Published: November 2020

Modern heritage buildings designed in the 1950s and 1960s often feature poor seismic performance capacities and may require significant retrofit interventions. A representative case study in Florence, i.e., the edifice housing the Automobile Club Headquarters, is examined here. The building was designed in 1959 with an articulated reinforced concrete structure and presents some enterprising solutions for the time, including suspended floors accommodating large glazed curtain wall façades in the main halls. The original design documentation was collected with accurate record research and checked with detailed on-site surveys. Based on the information gained on the structural system by this preliminary investigation, a time-history assessment analysis was carried out. Remarkable strength deficiencies in most members and severe pounding conditions between the two constituting wings, which are separated by a narrow technical gap, were found. As a result, a base isolation retrofit hypothesis is proposed in order to improve the seismic response capacities of the building without altering its elegant architectural appearance, being characterized by large free internal spaces and well-balanced proportions of the main structural members. A substantial performance improvement is obtained thanks to this rehabilitation strategy, as assessed by the achievement of non-pounding response conditions and safe stress states for all members up to the maximum considered normative earthquake level. Furthermore, the very low peak inter-storey drifts evaluated in retrofitted conditions help in preventing damage to the glazed façades and the remaining drift-sensitive non-structural components.
On Catalytic Behavior of Bulk Mo2C in the Hydrodenitrogenation of Indole over a Wide Range of Conversion Thereof
Authors: Lewandowski Marek , Janus Rafał , Wądrzyk Mariusz , Szymańska-Kolasa Agnieszka , Sayag Céline , Djéga-Mariadassou Gérald
Published: November 2020

The catalytic activity of bulk molybdenum carbide (Mo2C) in the hydrodenitrogenation (HDN) of indole was studied. The catalyst was synthesized using a temperature-programmed reaction of the respective oxide precursor (MoO3) with the carburizing gas mixture of 10 vol.\% CH4/H2. The resultant material was characterized using X-ray diffraction, CO chemisorption, and nitrogen adsorption. The catalytic activity was studied in the HDN of indole over a wide range of conversion thereof and in the presence of a low amount of sulfur (50 ppm), which was used to simulate the processing of real petroleum intermediates. The molybdenum carbide has shown high activity under the tested operating conditions. Apparently, the bulk molybdenum carbide turned out to be selective towards the formation of aromatic products such as ethylbenzene, toluene, and benzene. The main products of HDN were ethylbenzene and ethylcyclohexane. After 99% conversion of indole HDN was reached (i.e., lack of N-containing compounds in the products was observed), the hydrogenation of ethylbenzene to ethylcyclohexane took place. Thus, the catalytic behavior of bulk molybdenum carbide for the HDN of indole is completely different compared to previously studied sulfide-based systems.
Experimental and Modeling Analysis of Holey Graphene Electrodes for High-Power-Density Li-Ion Batteries
Authors: Huang Yu-Ren , Chen Cheng-Lung , Pu Nen-Wen , Wu Chia-Hung , Liu Yih-Ming , Chen Ying-Hsueh , Youh Meng-Jey , Ger Ming-Der
Published: November 2020

The performances of lithium-ion batteries (LIBs) using holey graphene (HGNS) as the anode material are compared with those using non-holey graphene (GNS). The effects of graphene holes on ion transport are analyzed with a combined experiment/modeling approach involving molecular dynamics (MD) simulations. The large aspect ratio of GNS leads to long transport paths for Li ions, and hence a poor rate capability. We demonstrate by both experiments and simulations that the holey structure can effectively improve the rate capability of LIBs by providing shortcuts for Li ion diffusion through the holes in fast charge/discharge processes. The HGNS anode exhibits a high specific capacity of 745 mAh/g at 0.1 A/g (after 80 cycles) and 141 mAh/g at a large current density of 10 A/g, which are higher than the capacity values of the GNS counterpart by 75% and 130%, respectively. MD simulations also reveal the difference in lithium ion transport between GNS and HGNS anodes. The calculations indicate that the HGNS system has a higher diffusion coefficient for lithium ions than the GNS system. In addition, it shows that the holey structure can improve the uniformity and quality of the solid electrolyte interphase (SEI) layer, which is important for Li ion conduction across this layer to access the electrode surface. Moreover, quantum chemistry (QC) computations show that ethylene carbonate (EC), a cyclic carbonate electrolyte with five-membered-ring molecules, has the lowest electron binding energy of 1.32 eV and is the most favorable for lithium-ion transport through the SEI layer. A holey structure facilitates uniform dispersion of EC on graphene sheets and thus enhances the Li ion transport kinetics.
Deposition and Growth of Functional Nanomaterials by LDW and MAPLE Techniques
Authors: Perez del Pino Angel
Published: November 2020

Actual societal challenges require a vigorous progress on functional materials with improved functionalities [...]
Is Ultrasound an Accurate Alternative for Mammography in Breast Cancer Screening in an Asian Population? A Meta-Analysis
Authors: Wang Jing , Zheng Senshuang , Ding Lanjun , Liang Xuan , Wang Yuan , Greuter Marcel J.W. , de Bock Geertruida H. , Lu Wenli
Published: November 2020

In Asian countries, ultrasound has been proposed as a possible alternative for mammography in breast cancer screening because of its superiority in dense breasts, accessibility and low costs. This research aimed to meta-analyze the evidence for the diagnostic performance of ultrasound compared to mammography for breast cancer screening in Asian women. PubMed, Web of Science, and China National Knowledge Infrastructure databases were searched for studies that concurrently compared mammography and ultrasound in 2000–2019. Data extraction and risk of bias were performed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA) statement. The primary outcome was the sensitivity and specificity. Bivariate random models were used to generate pooled estimates of diagnostic parameters and 95% confidence intervals (95% CI). In total, 4424 studies were identified of which six studies met the inclusion criteria with a sample size of 124,425 women. The pooled mean prevalence of the included studies was 3.7‰ (range: 1.2–5.7‰). The pooled sensitivity of mammography was significantly higher than that of ultrasound (0.81 [95% CI 0.71–0.88] versus 0.65 [95% CI 0.58–0.72], p = 0.03), but no significant differences were found in specificity (0.98 [95% CI: 0.94–1.00] versus 0.99 [95% CI: 0.97–1.00], p = 0.65). In conclusion, based on the currently available data on sensitivity alone, there is no indication that ultrasound can replace mammography in breast cancer screening in Asian women.
Diffusion Limitations and Translocation Barriers in Atomically Thin Biomimetic Pores
Authors: Sahu Subin , Zwolak Michael
Published: November 2020

Ionic transport in nano- to sub-nano-scale pores is highly dependent on translocation barriers and potential wells. These features in the free-energy landscape are primarily the result of ion dehydration and electrostatic interactions. For pores in atomically thin membranes, such as graphene, other factors come into play. Ion dynamics both inside and outside the geometric volume of the pore can be critical in determining the transport properties of the channel due to several commensurate length scales, such as the effective membrane thickness, radii of the first and the second hydration layers, pore radius, and Debye length. In particular, for biomimetic pores, such as the graphene crown ether we examine here, there are regimes where transport is highly sensitive to the pore size due to the interplay of dehydration and interaction with pore charge. Picometer changes in the size, e.g., due to a minute strain, can lead to a large change in conductance. Outside of these regimes, the small pore size itself gives a large resistance, even when electrostatic factors and dehydration compensate each other to give a relatively flat—e.g., near barrierless—free energy landscape. The permeability, though, can still be large and ions will translocate rapidly after they arrive within the capture radius of the pore. This, in turn, leads to diffusion and drift effects dominating the conductance. The current thus plateaus and becomes effectively independent of pore-free energy characteristics. Measurement of this effect will give an estimate of the magnitude of kinetically limiting features, and experimentally constrain the local electromechanical conditions.
COVID-19, Government Response, and Market Volatility: Evidence from the Asia-Pacific Developed and Developing Markets
Authors: Ibrahim Izani , Kamaludin Kamilah , Sundarasen Sheela
Published: November 2020

This study examines the relationship between COVID-19, government response measures, and stock market volatilities for 11 developed and developing economies within the Asia-Pacific region. Our period of study is between 15 February–30 May 2020. Using the continuous wavelet transformation (CWT) analysis and plots and GJR-GARCH analysis, we examined the effects of the COVID-19 public health crisis and the corresponding government measures on the respective domestic equity markets volatilities. The CWT plots showed a varying level of market volatilities at different investment horizons. All the sample countries, except Japan, experienced very low or low volatility over the short-term horizons. In contrast, Vietnam, Malaysia, and Laos experienced medium volatility over the medium-term horizons. Finally, China, Japan, South Korea, Malaysia, and the Philippines experienced high volatility over the long-term horizons. The GJR-GARCH results further ascertain that market volatilities are affected by domestic events, notably, the COVID-19 government intervention measures. In most sample countries, the government measures significantly reduce market volatility in the domestic equity markets. Additionally, international events have also triggered market volatilities. Overall, our study offers several contributions and implications for practitioners and policymakers.
Upgrading a Learning Context: Evaluation of Sintra’s Educational Project
Authors: Querido Lara , Capucha Luís , Nunes Nuno
Published: November 2020

The changes observed in the school context demand new practices and impose new challenges to the operational assistants that, due to their relevant role in the educational environment, must be prepared and endowed with knowledge and skills to conduct their profession in a fully useful way. This is only possible through the promotion of their training and capacitation in a real work context. Through the European project entitled “Innovative Plans to Combat School Failure” which was implemented in Portugal, we assess the impacts of a training-capacitation action directed to operational assistants and explore the dynamics and influences underlying the learning process put in practice in the schools of the county of Sintra. This assessment conducted by a higher education institution (Iscte-University Institute of Lisbon) mobilized a mixed methodology-survey and focus groups with operational assistants and interviews conducted to school directors. We verified that a training activity conducted in the real working context potentiates the performance of these professionals, namely in terms of autonomy and adaptation to different contexts and duties, conflict management and cooperation, whose effects reflected on the organizational dynamics of the school institutions of the county of Sintra.
Responding to Global Learning Needs during a Pandemic: An Analysis of the Trends in Platform Use and Incidence of COVID-19
Authors: Utunen Heini , George Richelle , Ndiaye Ngouille , Attias Melissa , Piroux Corentin , Gamhewage Gaya
Published: November 2020

On 11 March 2020, the World Health Organization (WHO) declared the outbreak of coronavirus disease (COVID-19) to be a pandemic. As a result, the OpenWHO.org online platform, which serves as WHO’s learning hub for emergencies, was tested for the first time on its core purpose of scaling up trusted public health information in a global emergency. This descriptive study examines and documents the WHO learning response in the early months of the pandemic by comparing epidemiological information and OpenWHO.org use in the countries with the highest COVID-19 cases. Statistical datasets from OpenWHO.org and WHO’s COVID-19 dashboard were overlaid for the period 11 March–22 May 2020. During this period, for most of the 24 countries with the highest COVID-19 cases, platform use showed a corresponding trend. Courses published in the official languages spoken in these countries were well utilized, indicating a need to produce materials in languages spoken by affected communities. Of the countries with the highest number of users on OpenWHO, only half were top users of the platform before the pandemic. The existence of an established online platform for health emergencies assisted WHO in massively and quickly scaling up the dissemination of essential learning materials for COVID-19.
A Systematic Review on Inclusive Education of Students with Visual Impairment
Authors: Miyauchi Hisae
Published: November 2020

This was a systematic review on the inclusive education of students with visual impairment. This study focused on two of the most addressed topics: the perceptions of general education teachers and challenges faced by students with visual impairment in accessing academic subjects. It synthesized the findings of 18 peer-reviewed articles published in English from 1980 to 2020. General education teachers’ attitudes toward the inclusion of students with visual impairment were both positive and negative and were influenced by teacher-, student-, and environment-related factors. Feeling unprepared, one of the main teacher-related factors, seemed to have a great effect. In terms of access to academic subjects, the most discussed subjects were Mathematics, Science, and Physical Education. Although students with visual impairment seemed to be studying at or above their grade level, their exclusion from participation in classroom activities was apparent. Unfortunately, these challenges lead to short- and long-term consequences. Key elements in increasing accessibility to subjects were: general education teachers possessing a generic set of effective pedagogical strategies, effective teaching-learning tools, and external support. The importance of teacher training and a holistic support system were emphasized.
Design and Optimization of Coupling Coils for Bidirectional Wireless Charging System of Unmanned Aerial Vehicle
Authors: Li Yang , Ni Xin , Liu Jiaming , Wang Rui , Ma Jingnan , Zhai Yujie , Huang Yuepeng
Published: November 2020

To solve the battery power supply problem with wireless sensor networks (WSNs), a novel bidirectional wireless charging system is proposed, in which an unmanned aerial vehicle (UAV) can fly to the WSNs to charge sensors through high-frequency wireless power transfer (WPT) and also obtain energy for its own battery in the same way. To improve the performance of the UAV bidirectional wireless charging system, a lightweight design is adopted to increase its loading capacity and working time. Moreover, the radii and the numbers of turns and pitches of coupling coils were designed and optimized on the basis of simulations and experiments. Experimental results show that the weight of optimized UAV coil was reduced by 34.45%. The power transfer efficiency (PTE) of the UAV coil to sensor coil increased from 60.2% to 74.4% at a transmission distance of 15 cm, while that of the ground transmitting coil to UAV coil increased from 65.2% to 90.1% at 10 cm.
A Power Efficient Frequency Divider With 55 GHz Self-Oscillating Frequency in SiGe BiCMOS
Authors: Centurelli Francesco , Monsurrò Pietro , Scotti Giuseppe , Tommasino Pasquale , Trifiletti Alessandro
Published: November 2020

A power efficient static frequency divider in commercial 55 nm SiGe BiCMOS technology is reported. A standard Current Mode Logic (CML)-based architecture is adopted, and optimization of layout, biasing and transistor sizes allows achieving a maximum input frequency of 63 GHz and a self-oscillating frequency of 55 GHz, while consuming 23.7 mW from a 3 V supply. This results in high efficiency with respect to other static frequency dividers in BiCMOS technology presented in the literature. The divider topology does not use inductors, thus optimizing the area footprint: the divider core occupies 60 × 65 μm2 on silicon.
Adaptive and Hybrid Idle–Hard Timeout Allocation and Flow Eviction Mechanism Considering Traffic Characteristics
Authors: Isyaku Babangida , Bakar Kamalrulnizam Abu , Zahid Mohd Soperi Mohd , Nura Yusuf Muhammed
Published: November 2020

Software-defined networking (SDN) enables flexible fine-grained networking policies by allowing the SDN controller to install packet handling rules on distributed switches. The behaviour of SDN depends on the set of forwarding entries installed at the switch flow table. The increasing number of traffics from the proliferation of the Internet of Thing (IoT) devices increase the processing load on the controller and generates an additional number of entries stored in the flow table. However, the switch flow table memory (TCAM) cannot accommodate many entries. Packets from multimedia flows are usually large in size and thus suffer processing delay and require more flow set up requests. The SDN controller may be overloaded and face some scalability problems because it supports a limited number of requests from switches. OpenFlow uses timeout configuration to manage flow setup request. The conventional fixed timeout cannot cope up with the dynamic nature of traffic flows. This paper controls the frequent flow setup requests by proposing an adaptive and hybrid idle–hard timeout allocation (AH-IHTA). The algorithm considers traffic patterns, flow table usage ratio, and returns appropriate the timeout to different flows. The performance evaluations conducted have shown a 28% and 39% reduction in the flow setup request and flow eviction, respectively.
Sustainable Smart Cities and Energy Management: The Labor Market Perspective
Authors: Pilipczuk Olga
Published: November 2020

Nowadays, sustainability is one of the strategic goals of smart cities. They are the essential solution to creating the sustainable future. On the other hand, the smart city is intended to deal with the problems of energy management. This paper examines the influence of the smart sustainable cities concept on energy management from the labor market perspective. The paper fulfills the research gap about energy manager profession transformation considering smart sustainable city concept. The aim of the paper is to create an up-to-date holistic energy manager skill model with a focus on emerging technologies. The skill model reflects the synergy of two methodological approaches: the theoretical and practical approaches. Descriptive statistics are used to present the labor market research results. It is concluded that the core elements of the smart sustainable city concept have an impact on energy management are sustainability and big data. The labor market research also draws differences in the amount and structure of demand on energy manager skills by countries, but at the same time similar skills requirements are found. The skill model of the energy manager profession is built around several main groups associated with specific knowledge, social skills, and behavior skills. The findings of the present research can contribute to knowledge and practice by applying it in the process of developing energy manager competency models in commercial and non-commercial enterprises as well as in education programs and training courses.
Coproduction of Acrylic Acid with a Biodiesel Plant Using CO2 as Reaction Medium: Process Modeling and Production Cost Estimation
Authors: Ye X. Philip , Ren Shoujie
Published: November 2020

Producing value-added chemicals from glycerol is imperative for the sustainable future of biodiesel. Despite worldwide efforts, the commercial production of acrylic acid from glycerol faces challenges, both technologically and economically. Based on our new technology using CO2 as a reaction medium in a two-step process to catalytically convert glycerol to acrylic acid, we established computer simulation models to analyze the energy efficiency and estimate production costs at different scenarios. The analysis was conducted in conjunction with published data of a typical, intermediate-sized biodiesel facility, aiming at the feasibility of producing acrylic acid on-site in the context of a circular economy. Variable analysis in response to the market value of glycerol, the source and cost of carbon dioxide recycling, and the changes in process scale and conditions are also presented. Results indicates that a cost-effective supply of CO2 to the acrylic acid plant is key to the further research and development.
Double Loop Network for Combined Heating and Cooling in Low Heat Density Areas
Authors: Tunzi Michele , Ruysschaert Matthieu , Svendsen Svend , Smith Kevin Michael
Published: November 2020

This study investigated a double loop network operated with ultra-low supply/return temperatures of 45/25 °C as a novel solution for low heat-density areas in Denmark and compared the proposed concept with a typical tree network and with individual heat pumps to each end-users rather than district networks. It is a pump-driven system, where the separate circulation of supply and return flow increased the flexibility of the system to integrate and displace heating and cooling energy along the network. Despite the increased use of central and local water pumps to operate and control the system, the simulated overall pump energy consumption was 0.9% of the total energy consumption. This was also an advantage at the design stage as the larger pressure gradient, up to 570 Pa/m, allowed minimal pipe diameters. In addition, the authors proposed the installation of electrically heated vacuum-insulated micro tanks of 10 L on the primary side of each building substation as a supplementary heating solution to meet the comfort and hygiene requirements for domestic hot water (DHW). This, combined with supply water circulation in the loop network, served as a technical solution to remove the need for bypass valves during summer periods with no load in the network. The proposed double loop system reduced distribution heat losses from 19% to 12% of the total energy consumption and decreased average return temperatures from 33 °C to 23 °C compared to the tree network. While excess heat recovery can be limited due to hydraulic issues in tree networks, the study investigated the double loop concept for scenarios with heat source temperatures of 30 °C and 45 °C. The double loop network was cost-competitive when considering the required capital and operating costs. Furthermore, district networks outperformed individual heat pump solutions for low-heat density areas when waste heat was available locally. Finally, although few in Denmark envisage residential cooling as a priority, this study investigated the potential of embedding heating and cooling in the same infrastructure. It found that the return line could deliver cold water to the end-users and that the maximum cooling power was 1.4 kW to each end-user, which corresponded to 47% of the total peak heat demand used to dimension the double loop network.
Highly Ordered TiO2 Nanotube Electrodes for Efficient Quasi-Solid-State Dye-Sensitized Solar Cells
Authors: Lee A Reum , Kim Jae-Yup
Published: November 2020

Free-standing TiO2 nanotube (NT) electrodes have attracted much attention for application in solid- or quasi-solid-state dye-sensitized solar cells (DSSCs) because of their suitable pore structure for the infiltration of solid electrolytes. However, few studies have been performed on the relationship between nanostructures of these NT electrodes and the photovoltaic properties of the solid- or quasi-solid-state DSSCs. Here, we prepare vertically aligned and highly ordered TiO2 NT electrodes via a two-step anodization method for application in quasi-solid-state DSSCs that employs a polymer gel electrolyte. The length of NT arrays is controlled in the range of 10–42 μm by varying the anodization time, and the correlation between NT length and the photovoltaic properties of quasi-solid-state DSSCs is investigated. As the NT length increases, the roughness factor of the electrode is enlarged, leading to the higher dye-loading; however, photovoltage is gradually decreased, resulting in an optimized conversion efficiency at the NT length of 18.5 μm. Electrochemical impedance spectroscopy (EIS) analysis reveals that the decrease in photovoltage for longer NT arrays is mainly attributed to the increased electron recombination rate with redox couples in the polymer gel electrolyte.
Renewable/Fuel Cell Hybrid Power System Operation Using Two Search Controllers of the Optimal Power Needed on the DC Bus
Authors: Bizon Nicu , Raceanu Mircea , Koudoumas Emmanouel , Marinoiu Adriana , Karapidakis Emmanuel , Carcadea Elena
Published: November 2020

In this paper, the optimal and safe operation of a hybrid power system based on a fuel cell system and renewable energy sources is analyzed. The needed DC power resulting from the power flow balance on the DC bus is ensured by the FC system via the air regulator or the fuel regulator controlled by the power-tracking control reference or both regulators using a switched mode of the above-mentioned reference. The optimal operation of a fuel cell system is ensured by a search for the maximum of multicriteria-based optimization functions focused on fuel economy under perturbation, such as variable renewable energy and dynamic load on the DC bus. Two search controllers based on the global extremum seeking scheme are involved in this search via the remaining fueling regulator and the boost DC–DC converter. Thus, the fuel economy strategies based on the control of the air regulator and the fuel regulator, respectively, on the control of both fueling regulators are analyzed in this study. The fuel savings compared to fuel consumed using the static feed-forward control are 6.63%, 4.36% and 13.72%, respectively, under dynamic load but without renewable power. With renewable power, the needed fuel cell power on the DC bus is lower, so the fuel cell system operates more efficiently. These percentages are increased to 7.28%, 4.94% and 14.97%.
Quantification of Minor Chemical Elements in Particulate Matter Collected from In-Use Diesel Engine Passenger Vehicles by Laser-Induced Breakdown Spectroscopy
Authors: Viskup Richard , Wolf Christoph , Baumgartner Werner
Published: November 2020

This research qualitatively and quantitatively characterises the minor chemical elements in diesel particulate matter (DPM). DPM was extracted from in-use diesel engine passenger vehicles of diverse types and models from major brand car producers in Europe. We analysed particulate matter extracted from the exhaust manifold part from passenger vehicles that are used in daily life environment. To qualitatively and quantitatively characterise the DPM, we employed the high-resolution Laser-Induced Breakdown Spectroscopy analytical technique (LIBS). Qualitative spectrochemical LIBS analyses confirmed the presence of minor chemical elements—silicon, nickel, titan, potassium, strontium, and molybdenum in DPM. For quantification of the LIBS signal, the calibration functions were constructed from internal calibration standards. Different concentrations of detected minor elements Si, Ni, Ti, K, Sr, and Mo were measured with respect to the type of complex particulate matter.
A Family of High Voltage Gain Three-Level Step-Up Converters for Photovoltaic Module Integration Applications
Authors: Alzahrani Ahmad , Shamsi Pourya , Ferdowsi Mehdi
Published: November 2020

This paper proposes a family of step-up three-level DC-DC converter topologies suitable for photovoltaic panel integration applications. The proposed family is suitable to convert the 10–30 V from photovoltaic panels to a 150 V direct current distribution bus. The proposed family enhances the three-level topology in terms of the voltage gain, power density, and filtering requirements at the input level. The filtration is reduced by interleaving. The three-level boost converter’s voltage gain is enhanced by utilizing several options such as switched capacitor cells, switched inductor cells, and flyback transformers or coupled inductors. The enhancement techniques are illustrated by providing the circuit diagram and a comparison of the voltage gain and the number of required components. An example converter of a hybrid three-level boost converter with a flyback transformer is presented to convert 20 V from a photovoltaic panel to a 400 V. The theory of operation and steady-state analysis are provided for the example converter operating in the continuous conduction mode. The converter is simulated to extract the power from three PVL-136 photovoltaic (PV) panels by applying a maximum power point tracking algorithm. The theory of operation and simulation are confirmed with an 80 W experimental prototype, which has an efficiency of around 95% at 40 W load power.
Real-Time Pricing Scheme in Smart Grid Considering Time Preference: Game Theoretic Approach
Authors: Piao Ri , Lee Deok-Joo , Kim Taegu
Published: November 2020

Unbalanced power demand across time slots causes overload in a specific time zone. Various studies have proved that this can be mitigated through smart grid and price policy, but research on time preference is insufficient. This study proposed a real-time pricing model on a smart grid through a two-stage Stackelberg game model based on a utility function that reflects the user’s time preference. In the first step, the suppliers determine the profit-maximizing price, and then, the users decide the electricity usage schedule according to the given price. Nash equilibrium and comparative analysis of the proposed game explain the relationship between time preference, price, and usage. Additionally, a Monte Carlo simulation demonstrated the effect of the change in time preference distribution. The experimental results confirmed that the proposed real-time pricing method lowers peak-to-average ratio (PAR) and increases overall social welfare. This study is meaningful in that it presents a pricing method that considers both users’ and suppliers’ strategies with time preference. It is expected that the proposed method would contribute to a reduction in the need for additional power generation facilities through efficient operation of the smart grid.
Numerical and Experimental Analysis of Heat Transfer for Solid Fuels Combustion in Fixed Bed Conditions
Authors: Judt Wojciech
Published: November 2020

The paper concerns the analysis of the heat transfer process that occurred during solid fuel burning in fixed bed conditions. The subject of the analysis is a cylindrical combustion chamber with an output of 12 kW heating power equipped with a retort burner for hard coal and biomass combustion. During the research, a numerical and experimental study is performed. The analysis is prepared for various heat load of the combustion chamber, which allowed for the reconstruction of real working conditions for heating devices working with solid fuels combustion. The temperature distribution obtained by the experimental way is compared with results of the numerical modeling. Local distribution of principal heat transfer magnitudes like a heat flux density and a heat transfer coefficient that occurred on the sidewall of the combustion chamber is analyzed. The analysis showed, that the participation of convection and radiation in the overall heat transfer process has resulted from the heat load of the heating device. Research results may be used for improving an analytical approach of design process taking place for domestic and industrial combustion chambers.