bluuebunny/crossref_metadata_2025 huggingface dataset:
Rhizobium-Linked Nutritional and Phytochemical Changes Under Multitrophic Functional Contexts in Sustainable Food Systems
Authors: Ochieno Dennis M. W. , Karoney Edwin M. , Muge Edward K. , Nyaboga Evans N. , Baraza Danstone L. , Shibairo Solomon I. , Naluyange Victoria
Published: January 2021

Rhizobia are bacteria that exhibit both endophytic and free-living lifestyles. Endophytic rhizobial strains are widely known to infect leguminous host plants, while some do infect non-legumes. Infection of leguminous roots often results in the formation of root nodules. Associations between rhizobia and host plants may result in beneficial or non-beneficial effects. Such effects are linked to various biochemical changes that have far-reaching implications on relationships between host plants and the dependent multitrophic biodiversity. This paper explores relationships that exist between rhizobia and various plant species. Emphasis is on nutritional and phytochemical changes that occur in rhizobial host plants, and how such changes affect diverse consumers at different trophic levels. The purpose of this paper is to bring into context various aspects of such interactions that could improve knowledge on the application of rhizobia in different fields. The relevance of rhizobia in sustainable food systems is addressed in context.
Evolution and Stagnation of Image Guidance for Surgery in the Lateral Skull: A Systematic Review 1989–2020
Authors: Schneider Daniel , Hermann Jan , Mueller Fabian , Braga Gabriela O'Toole Bom , Anschuetz Lukas , Caversaccio Marco , Nolte Lutz , Weber Stefan , Klenzner Thomas
Published: January 2021

Objective: Despite three decades of pre-clinical and clinical research into image guidance solutions as a more accurate and less invasive alternative for instrument and anatomy localization, translation into routine clinical practice for surgery in the lateral skull has not yet happened. The aim of this review is to identify challenges that need to be solved in order to provide image guidance solutions that are safe and beneficial for use during lateral skull surgery and to synthesize factors that facilitate the development of such solutions.

Methods: Literature search was conducted via PubMed using terms relating to image guidance and the lateral skull. Data extraction included the following variables: image guidance error, imaging resolution, image guidance system, tracking technology, registration method, study endpoints, clinical target application, and publication year. A subsequent search of FDA 510(k) database for identified image guidance systems and extraction of the year of approval, intended use, and indications for use was performed. The study objectives and endpoints were subdivided in three time phases and summarized. Furthermore, it was analyzed which factors correlated with the image guidance error. Factor values for which an error ≤0.5 mm (μerror + 3σerror) was measured in more than one study were identified and inspected for time trends.

Results: A descriptive statistics-based summary of study objectives and findings separated in three time intervals is provided. The literature provides qualitative and quantitative evidence that image guidance systems must provide an accuracy ≤0.5 mm (μerror + 3σerror) for their safe and beneficial application during surgery in the lateral skull. Spatial tracking accuracy and precision and medical image resolution both correlate with the image guidance accuracy, and all of them improved over the years. Tracking technology with accuracy ≤0.05 mm, computed tomography imaging with slice thickness ≤0.2 mm, and registration based on bone-anchored titanium fiducials are components that provide a sufficient setting for the development of sufficiently accurate image guidance.

Conclusion: Image guidance systems must reliably provide an accuracy ≤0.5 mm (μerror + 3σerror) for their safe and beneficial use during surgery in the lateral skull. Advances in tracking and imaging technology contribute to the improvement of accuracy, eventually enabling the development and wide-scale adoption of image guidance solutions that can be used safely and beneficially during lateral skull surgery.
Artificial microRNA-Based RNA Interference and Specific Gene Silencing for Developing Insect Resistance in Solanum lycopersicum
Authors: Faisal Mohammad , Abdel-Salam Eslam M. , Alatar Abdulrahman A.
Published: January 2021

RNA Interference (RNAi), which works against invading nucleic acids or modulates the expression of endogenous genes, is a natural eukaryotic regulating system, and it works by noncoding smaller RNA molecules. Plant-mediated gene silencing through RNAi can be used to develop plants with insect tolerance at transcriptional or post-transcriptional levels. In this study, we selected Myzus persicae’s acetylcholinesterase 1 gene (Ace 1) as a silencing target to develop transgenic Solanum lycopersicum L. plants’ resistance to aphids. An RNAi plasmid vector containing an artificial microRNA (amiRNA) sequence was engineered and successfully transformed into Jamila and Tomaland, two elite tomato cultivars. A northern blot analysis and PCR were carried out to check the efficacy of Agrobacterium-mediated transformation in T0 transgenic plants. The quantitative PCR data showed a substantial downregulation of the Ace 1 gene in aphids fed in clip cages on T1 transgenic plants. Furthermore, there was a substantial drop in aphid colonies that were fed on T1 transgenic plants of both the cultivars. These findings strongly suggest that transgenic plants that express amiRNA could be an important tool for engineering plants resistant to aphids and possibly for the prevention of viral disease in other plant-infested pests.
Diversifying the Landscape with Animal Integration: An Introduction to the Environmental Sustainability of Crop–Livestock Systems
Authors: Delate Kathleen , Heins Bradley J.
Published: January 2021

In this Special Issue of “Environmental Sustainability of Crop–Livestock Systems,” we collected eleven articles that represent a wide breadth of integrated systems around the world, including the U [...]
Clinical Presentation and Incidence of Anaerobic Bacteria in Surgically Treated Biliary Tract Infections and Cholecystitis
Authors: Strohäker Jens , Wiegand Lisa , Beltzer Christian , Königsrainer Alfred , Ladurner Ruth , Meier Anke
Published: January 2021

(1) Background: Cholecystitis and cholangitis are among the most common diseases treated by general surgery. Gallstones lead to inflammation and bacterial infection of the biliary tract. Biliary infections can lead to live threatening bacteremia and liver abscesses. The true role of anaerobes remains unclear. (2) Methods: We retrospectively analyzed bacterial cultures from biliary samples obtained from bile ducts and gallbladders at our tertiary care center. Patient characteristics and clinical outcomes were analyzed. (3) Results: In our database of 1719 patients, 365 patients had microbial testing, of which 42 grew anaerobic bacteria. Anaerobes were more frequently cultured in patients with hepatic abscesses and gallbladder perforation. These patients were older and had more comorbidities than the control group. The overall outcomes of all patients were favorable and the resistance rate to commonly used antibiotics remained low. (4) Conclusions: Anaerobes in biliary tract infections appear to be underdiagnosed and more prevalent in the elderly with advanced disease. Due to low antibiotic resistance, the combination of source control and adjunct anti-infective treatment leads to favorable outcomes.
Photon-In/Photon-Out X-ray Free-Electron Laser Studies of Radiolysis
Authors: Young Linda , Nienhuis Emily T. , Koulentianos Dimitris , Doumy Gilles , March Anne Marie , Southworth Stephen H. , Clark Sue B. , Orlando Thomas M. , LaVerne Jay A. , Pearce Carolyn I.
Published: January 2021

Understanding the origin of reactive species following ionization in aqueous systems is an important aspect of radiation–matter interactions as the initial reactive species lead to production of radicals and subsequent long-term radiation damage. Tunable ultrafast X-ray free-electron pulses provide a new window to probe events occurring on the sub-picosecond timescale, supplementing other methodologies, such as pulse radiolysis, scavenger studies, and stop flow that capture longer timescale chemical phenomena. We review initial work capturing the fastest chemical processes in liquid water radiolysis using optical pump/X-ray probe spectroscopy in the water window and discuss how ultrafast X-ray pump/X-ray probe spectroscopies can examine ionization-induced processes more generally and with better time resolution. Ultimately, these methods will be applied to understanding radiation effects in complex aqueous solutions present in high-level nuclear waste.
An Adaptive Model Predictive Voltage Control for LC-Filtered Voltage Source Inverters
Authors: Gholami-Khesht Hosein , Davari Pooya , Blaabjerg Frede
Published: January 2021

The three-phase inductor and capacitor filter (LC)-filtered voltage source inverter (VSI) is subjected to uncertain and time-variant parameters and disturbances, e.g., due to aging, thermal effects, and load changes. These uncertainties and disturbances have a considerable impact on the performance of a VSI’s control system. It can degrade system performance or even cause system instability. Therefore, considering the effects of all system uncertainties and disturbances in the control system design is necessary. In this respect and to tackle this issue, this paper proposes an adaptive model predictive control (MPC), which consists of three main parts: an MPC, an augmented state-space model, and an adaptive observer. The augmented state-space model considers all system uncertainties and disturbances and lumps them into two disturbance inputs. The proposed adaptive observer determines the lumped disturbance functions, enabling the control system to keep the nominal system performance under different load conditions and parameters uncertainty. Moreover, it provides load-current-sensorless operation of MPC, which reduces the size and cost, and simultaneously improves the system reliability. Finally, MPC selects the proper converter voltage vector that minimizes the tracking errors based on the augmented model and outputs of the adaptive observer. Simulations and experiments on a 5 kW VSI examine the performance of the proposed adaptive MPC under different load conditions and parameter uncertainties and compare them with the conventional MPC.
Spatial Distribution of Spray from a Solid Set Canopy Delivery System in a High-Density Apple Orchard Retrofitted with Modified Emitters
Authors: Ranjan Rakesh , Sinha Rajeev , Khot Lav R. , Hoheisel Gwen-Alyn , Grieshop Matthew , Ledebuhr Mark
Published: January 2021

Solid Set Canopy Delivery Systems (SSCDS) are fixed agrochemical delivery systems composed of a network of micro-sprayers/nozzles distributed in perennial crop canopies. A previous SSCDS design composed of a 3-tier configuration using hollow cone sprayer nozzles has been shown to provide excellent coverage and deposition in high-density apple orchards. However, the hollow cone nozzles substantially increases the initial system installation costs. This study evaluated the effect of irrigation micro-emitters replacement on spray deposition, coverage and off-target drift. A micro-emitter used in greenhouse irrigation systems was duly modified to enhance its applicability with SSCDS. After laboratory assessment and optimization of the micro-emitters, a replicated field study was conducted to compare 3-tier SSCDS configured with either of modified irrigation micro-emitters or traditional hollow cone nozzles. Canopy deposition and off target drift were evaluated using a 500 ppm fluorescent tracer solution sprayed by the field installed systems and captured on mylar collectors. Spray coverage was evaluated using water sensitive papers. The overall canopy deposition and coverage for treatment configured with modified irrigation micro-emitters (955.5 ± 153.9 [mean ± standard error of mean] ng cm−2 and 22.7 ± 2.6%, respectively) were numerically higher than the hollow cone nozzles (746.2 ± 104.7 ng cm−2 and 19.0 ± 2.8%, respectively). Moreover, modified irrigation micro-emitter SSCDS had improved spray uniformity in the canopy foliage and on either side of leaf surfaces compared to a hollow cone nozzle. Ground and aerial spray losses, quantified as deposition, were numerically lower for the modified irrigation micro-emitter (121.8 ± 43.4 ng cm−2 and 0.7 ± 0.1 ng cm−2, respectively) compared to the traditional hollow cone nozzle (447.4 ± 190.9 ng cm−2 and 3.2 ± 0.4 ng cm−2, respectively). Overall, the modified irrigation micro-emitter provided similar or superior performance to the traditional hollow cone nozzle with an estimated 12 times reduction in system installation cost.
Design of SWB Antenna with Triple Band Notch Characteristics for Multipurpose Wireless Applications
Authors: Balani Warsha , Sarvagya Mrinal , Ali Tanweer , Samasgikar Ajit , Das Saumya , Kumar Pradeep , Anguera Jaume
Published: January 2021

A compact concentric structured monopole antenna for super wide band (SWB) applications with triple notch band characteristics is designed and experimentally validated. The antenna covers an immense impedance bandwidth (1.6–47.5 GHz) with sharp triple notch bands at 1.8–2.2 GHz, 4–7.2 GHz, and 9.8–10.4 GHz to eliminate interference from co-existing advanced wireless services (AWS), C bands, and X bands, respectively. By loading an E-shaped stub connected at the top of the patch and by etching a split elliptical slot at the lower end of the radiating patch, the band rejection characteristics from 1.8–2.2 GHz for the AWS and 4–7.2 GHz for the C band are achieved, respectively. Further, by making use of a C-shaped resonator near the feed line, band rejection from 9.8–10.4 GHz for the X band is obtained. By varying the parameters of the antenna, the notch bands are controlled independently over a wide range of frequencies. The antenna provides good radiation characteristics, constant group delay response, and better gain over the pass band. The experimental results indicate that the designed antenna offers a remarkable reduction in gain and high variation in group delay over the stop bands. To characterize the wideband property and linear phase response of the designed antenna, its time-domain performance is extensively described and evaluated, which assure pulse transmission with minimum distortion.
Effects of Crop Protection Unmanned Aerial System Flight Speed, Height on Effective Spraying Width, Droplet Deposition and Penetration Rate, and Control Effect Analysis on Wheat Aphids, Powdery Mildew, and Head Blight
Authors: Zhang Songchao , Qiu Baijing , Xue Xinyu , Sun Tao , Gu Wei , Zhou Fuliang , Sun Xiangdong
Published: January 2021

As a new type of crop protection machinery, the Crop Protection Unmanned Aerial System (CPUAS) has developed rapidly and been widely used in China; currently, how to use the CPUAS scientifically has become a top priority. However, the relationships between the operating parameters of the CPUAS and the effective spraying width (ESW), droplet distribution characteristics, and control effects of insect pests and diseases are not clear yet. Therefore, three levels of flight speed (FS) as 3, 4, and 5 m/s, three levels of flight height (FH) as 1.5, 2.0, and 2.5 m, and spraying volume 2.0 L/min experiments were carried out to investigate the effects of FS and FH on the ESW, droplet deposition uniformity (DDU), and droplet penetration rate (DPR) by using an electric single-rotor CPUAS CE20. Based on the obtained results, combined with the insect pests and diseases occurrence agronomic laws, the optimal operation parameters of the CPUAS were selected to control the wheat aphids, powdery mildew, and head blight. The results showed that the ESW of CE20 was not consistent, the maximum value was 5.78 m, and the minimum one was 2.51 m. The FS had a highly significant impact on ESW (p = 0.0033 < 0.01), while the FH and the interaction between FS and FH had no significant impact on ESW. The coefficients of variation (CV) of the droplet deposition were between 23.3% and 34.4%, which meant good deposition uniformity. The FH (p = 0.0019) and the interaction between FS and FH (p = 0.02) had significant impacts on the DDU. The control effects on aphids were 78.71% (1 day), 84.88% (3 days), and 90.42% (7 days), the control effects on powdery mildew were 77.17% (7 days) and 82.83% (14 days), and the control effect on head blight was 88.32% (20 days). This study proved that by the optimization of parameters and the combination of agronomy, good control effects for insect pests and diseases could be achieved by the CPUAS. The research results would provide some technical supports for CPUAS application.
Cutaneous Manifestations in COVID-19: Report on 31 Cases from Five Countries
Authors: Rodriguez-Cerdeira Carmen , Uribe-Camacho Brianda I. , Silverio-Carrasco Lianet , Méndez Wennia , Mahesh Ashwini R. , Tejada Anakaren , Beirana Angelica , Martinez-Herrera Erick , Alba Alfonso , Arenas Roberto , Szepietowski Jacek C.
Published: January 2021

The increasingly frequent cutaneous manifestations of coronavirus disease (COVID-19) remain to pose a problem to clinicians. Herein, we aimed to describe the clinical and pathological findings of skin lesions in patients with COVID-19. The case series, which was based on the International Dermatological Registry circulated to dermatologists worldwide, was conducted across organizations and societies belonging to five different countries. We documented 31 patients with dermatologic manifestations associated with COVID-19, including maculopapular rashes (16.10%), urticarial lesions (26.80%), pseudochilblains (22.60%), petechiae/purpura (6.50%), distal ischaemia and necrosis (6.50%), livedo racemosa (12.90%), and others (9.70%). Twenty-six cases (83.90%) were qRT-PCR-confirmed COVID-19 cases, two (6.50%) were serologically confirmed, while two others (9.7%) were suspected cases owing to previous contact with COVID-19-positive patients. Therefore, our findings indicate that a febrile rash or even a rash in an afebrile state in the early stages of the disease may be the only clinical manifestation of COVID-19. In the future, we recommend close monitoring of all patients with skin lesions not attributable to other causal factors; in the diagnostic perspective, clinicians should aim to confirm if the skin lesions are associated with COVID-19.
Development of Non-Porous Silica Nanoparticles towards Cancer Photo-Theranostics
Authors: Mochizuki Chihiro , Nakamura Junna , Nakamura Michihiro
Published: January 2021

Nanoparticles have demonstrated several advantages for biomedical applications, including for the development of multifunctional agents as innovative medicine. Silica nanoparticles hold a special position among the various types of functional nanoparticles, due to their unique structural and functional properties. The recent development of silica nanoparticles has led to a new trend in light-based nanomedicines. The application of light provides many advantages for in vivo imaging and therapy of certain diseases, including cancer. Mesoporous and non-porous silica nanoparticles have high potential for light-based nanomedicine. Each silica nanoparticle has a unique structure, which incorporates various functions to utilize optical properties. Such advantages enable silica nanoparticles to perform powerful and advanced optical imaging, from the in vivo level to the nano and micro levels, using not only visible light but also near-infrared light. Furthermore, applications such as photodynamic therapy, in which a lesion site is specifically irradiated with light to treat it, have also been advancing. Silica nanoparticles have shown the potential to play important roles in the integration of light-based diagnostics and therapeutics, termed “photo-theranostics”. Here, we review the recent development and progress of non-porous silica nanoparticles toward cancer “photo-theranostics”.
First-Principles Study of the Electronic Properties and Thermal Expansivity of a Hybrid 2D Carbon and Boron Nitride Material
Authors: Olaniyan Okikiola , Moskaleva Lyudmila V.
Published: January 2021

In an attempt to push the boundary of miniaturization, there has been a rising interest in two-dimensional (2D) semiconductors with superior electronic, mechanical, and thermal properties as alternatives for silicon-based devices. Due to their fascinating properties resulting from lowering dimensionality, hexagonal boron nitride (h-BN) and graphene are considered promising candidates to be used in the next generation of high-performance devices. However, neither h-BN nor graphene is a semiconductor due to a zero bandgap in the one case and a too large bandgap in the other case. Here, we demonstrate from first-principles calculations that a hybrid 2D material formed by cross-linking alternating chains of carbon and boron nitride (HCBN) shows promising characteristics combining the thermal merits of graphene and h-BN while possessing the electronic structure characteristic of a semiconductor. Our calculations demonstrate that the thermal properties of HCBN are comparable to those of h-BN and graphene (parent systems). HCBN is dynamically stable and has a bandgap of 2.43 eV. At low temperatures, it exhibits smaller thermal contraction than the parent systems. However, beyond room temperature, in contrast to the parent systems, it has a positive but finitely small linear-thermal expansion coefficient. The calculated isothermal bulk modulus indicates that at high temperatures, HCBN is less compressible, whereas at low temperatures it is more compressible relative to the parent systems. The results of our study are important for the rational design of a 2D semiconductor with good thermal properties.
The Influence of Socioeconomic Factors on Households’ Vulnerability to Climate Change in Semiarid Towns of Mopani, South Africa
Authors: Jimoh Musa , Bikam Peter , Chikoore Hector
Published: January 2021

The changing climate and its current rate, frequency, as well as its life-threatening impacts are undoubtedly abnormal and globally worrisome. Its effects are expected to be severely different across segments of the society. It is disposed to leaving no facet of human endeavor immune, particularly in vulnerable cities of developing countries where there is dearth of empirical studies. For the context-specific nature of climate change impacts and place-based character of vulnerability, this study explores the influence of socioeconomic attributes on household vulnerability in Mopani District northeast of South Africa to provide basis for targeting, formulating, evaluating, and monitoring adaptation policies, programs, and projects. The study adopted a multistage random sampling to draw 500 households from six towns in Mopani District, Limpopo Province. Mixed methods approach was used for data collection, while Household Vulnerability Index (HVI) was estimated using principal component analysis and regressed with socioeconomic attributes. The study reveals that climate is changing with high HVI across selected towns. It further depicted that age and marital status have positive and significant relationships with HVI, while gender and educational levels have inverse and significant relationship with HVI in some towns. The study recommends the need for municipalities to partner with private sector to empower household and mainstream micro level coping strategies in urban planning across the district.
Effects of Energy Supply from Roughage and Concentrates and the Occurrence of Subclinical Ketosis on Blood Chemistry and Liver Health in Lactating Dairy Cows during Early Lactation
Authors: Schmitz Rolf , Schnabel Karina , Frahm Jana , von Soosten Dirk , Meyer Ulrich , Hüther Liane , Spiekers Hubert , Rehage Jürgen , Sauerwein Helga , Dänicke Sven
Published: January 2021

The objectives of this study were to examine the effects of varying dietary energy supply as well as the impacts of subclinical ketosis (SCK) on blood chemistry and liver health. A total 63 German-Holstein cows were housed from three weeks antepartum until sixteen weeks postpartum. After calving, cows were assigned to one of four treatment groups receiving either moderate or high energy concentrations in roughage and secondly moderate or high amounts of concentrates. Retrospectively, cows were additionally grouped according to their β-hydroxybutyrate concentration (SK: cows with SCK vs. CON: cows without SCK). The different energy supply of treatment groups had little effects on blood and liver variables; greater differences occurred between SK and CON cows. Liver fat content of SK cows was 34% higher compared to CON cows. Also, the activity of aspartate aminotransferase and γ-glutamyl transferase, bilirubin concentration, and percentage of granulocytes were increased in SK cows. The results indicate that cows were able to adjust their metabolism to different dietary energy supplies without having a clearly increased risks for metabolic disorders. However, individual animals of all groups developed a metabolic derailment during the postpartum period resulting in SCK, which is closely connected with impaired liver function, compromised immune-responsiveness, and elevated oxidative stress.
Deep Task-Based Quantization
Authors: Shlezinger Nir , Eldar Yonina C.
Published: January 2021

Quantizers play a critical role in digital signal processing systems. Recent works have shown that the performance of acquiring multiple analog signals using scalar analog-to-digital converters (ADCs) can be significantly improved by processing the signals prior to quantization. However, the design of such hybrid quantizers is quite complex, and their implementation requires complete knowledge of the statistical model of the analog signal. In this work we design data-driven task-oriented quantization systems with scalar ADCs, which determine their analog-to-digital mapping using deep learning tools. These mappings are designed to facilitate the task of recovering underlying information from the quantized signals. By using deep learning, we circumvent the need to explicitly recover the system model and to find the proper quantization rule for it. Our main target application is multiple-input multiple-output (MIMO) communication receivers, which simultaneously acquire a set of analog signals, and are commonly subject to constraints on the number of bits. Our results indicate that, in a MIMO channel estimation setup, the proposed deep task-bask quantizer is capable of approaching the optimal performance limits dictated by indirect rate-distortion theory, achievable using vector quantizers and requiring complete knowledge of the underlying statistical model. Furthermore, for a symbol detection scenario, it is demonstrated that the proposed approach can realize reliable bit-efficient hybrid MIMO receivers capable of setting their quantization rule in light of the task.
Brand and Firm Value: Evidence from Arab Emerging Markets
Authors: Mousa Musaab , Sági Judit , Zéman Zoltán
Published: January 2021

This study aims to estimate the impact of brand as the most important intangible marketing asset on firm value, measured by share return in some Arab emerging market, as well analyze the moderating role of agency costs in the relationship between share return and brand. We use the Ohlson model of valuation with a sample of the most traded companies on four markets under study. The panel data regression results show a significant impact of brand on return as well as agency costs that promote the valuation model power, meaning that good corporate governance increases the degree of marketing investment efficiency in value creation. Our findings support the literature relating to the residual earnings valuation model. Furthermore, the results confirm the informative content of marketing application besides the traditional accounting figures as a promising approach for firm valuation.
Development of an Ethernet-Based Heuristic Time-Sensitive Networking Scheduling Algorithm for Real-Time In-Vehicle Data Transmission
Authors: Kim Hyeong-Jun , Choi Min-Hee , Kim Mah-Ho , Lee Suk
Published: January 2021

The rapid development and adaptation of advanced driver assistance systems (ADAS) and autonomous driving increases the burden of in-vehicle networks. In-vehicle networks are now required to provide a fast data rate and bounded delay for real-time operation, while conventional protocols such as controller area networks, local interconnected networks, and FlexRay begin to show limitations. Ethernet-based time-sensitive network (TSN) technology has been proposed as an alternative. TSN is a set of Ethernet standards being developed by the IEEE TSN task group, which aims to satisfy requirements such as real-time operation, stability, and low and bounded latency, and it can be used in automotive, industrial, and aerospace applications. This study introduces several standards for Ethernet traffic scheduling based on TSN technology and proposes a heuristic-based scheduling algorithm for Ethernet scheduling. In addition, three network configurations are simulated using OMNeT++ to show the applicability. The heuristic TSN scheduling algorithm is a straightforward and systematic procedure for practical network designers.
Design of a Resonant Converter for a Regenerative Braking System Based on Ultracap Storage for Application in a Formula SAE Single-Seater Electric Racing Car
Authors: Dolara Alberto , Leva Sonia , Moretti Giacomo , Mussetta Marco , de Novaes Yales Romulo
Published: January 2021

Electric mobility can represent a game changing technology for the long-term sustainability of the transportation sector. Pursuing this target, a model to simulate an Electric Vehicle (EV) for Formula SAE Electric competition is herein proposed: all the subsystems of the EV and the hybrid storage of the Li-ion batteries and Ultra-Capacitors (UCs) are implemented, in order to store the kinetic energy of the regenerative braking in the storage system through the Kinetic Energy Recovery System (KERS). A bidirectional DC-DC resonant converter is herein applied to the KERS to manage the UC pack. The operational limits of the proposed system, keeping the soft-switching properties, are discussed, and the results show the capability of the converter to operate under resonant mode in both boost and buck mode. A drawback is the presence of high current peaks in the resonant inductor. The use of more than one converter in interleaving and the adoption of a suitable capability factor ensure the proper operation of the system.
Achieving Balanced Load Distribution with Reinforcement Learning-Based Switch Migration in Distributed SDN Controllers
Authors: Yeo Sangho , Naing Ye , Kim Taeha , Oh Sangyoon
Published: January 2021

Distributed controllers in software-defined networking (SDN) become a promising approach because of their scalable and reliable deployments in current SDN environments. Since the network traffic varies with time and space, a static mapping between switches and controllers causes uneven load distribution among controllers. Dynamic migration of switches methods can provide a balanced load distribution between SDN controllers. Recently, existing reinforcement learning (RL) methods for dynamic switch migration such as MARVEL are modeling the load balancing of each controller as linear optimization. Even if it is widely used for network flow modeling, this type of linear optimization is not well fitted to the real-world workload of SDN controllers because correlations between resource types are unexpectedly and continuously changed. Consequently, using the linear model for resource utilization makes it difficult to distinguish which resource types are currently overloaded. In addition, this yields a high time cost. In this paper, we propose a reinforcement learning-based switch and controller selection scheme for switch migration, switch-aware reinforcement learning load balancing (SAR-LB). SAR-LB uses the utilization ratio of various resource types in both controllers and switches as the inputs of the neural network. It also considers switches as RL agents to reduce the action space of learning, while it considers all cases of migrations. Our experimental results show that SAR-LB achieved better (close to the even) load distribution among SDN controllers because of the accurate decision-making of switch migration. The proposed scheme achieves better normalized standard deviation among distributed SDN controllers than existing schemes by up to 34%.
Networked VR: State of the Art, Solutions, and Challenges
Authors: Ruan Jinjia , Xie Dongliang
Published: January 2021

The networking of virtual reality applications will play an important role in the emerging global Internet of Things (IoT) framework and it is expected to provide the foundation of the expected 5G tactile Internet ecosystem. However, considerable challenges are ahead in terms of technological constraints and infrastructure costs. The raw data rate (5 Gbps–60 Gbps) required achieving an online immersive experience that is indistinguishable from real life vastly exceeds the capabilities of future broadband networks. Therefore, simply providing high bandwidth is insufficient in compensating for this difference, because the demands for scale and supply vary widely. This requires exploring holistic solutions that exceed the traditional network domain, and integrating virtual reality (VR) data capture, encoding, network, and user navigation. Emerging services are extremely inefficient in terms of mass use and data management, which significantly reduces the user experience, due to their heuristic design choices. Other key aspects must be considered, such as wireless operation, ultra-low latency, client/network access, system deployment, edge computing/cache, and end-to-end reliability. A vast number of high-quality works have been published in this area and they will be highlighted in this survey. In addition to a thorough summary of recent progress, we also present an outlook of future developments in the quality of immersive experience networks and unified data set measurement in VR video transmission, focusing on the expansion of VR applications, security issues, and business issues, which have not yet been addressed, and the technical challenges that have not yet been completely solved. We hope that this paper will help researchers and developers to gain a better understanding of the state of research and development in VR.
Performance of a Shunt Active Power Filter for Unbalanced Conditions Using Only Current Measurements
Authors: Al-Gahtani Saad F. , Nelms R. M.
Published: January 2021

Shunt active power filters (APFs) are used to address power quality issues such as harmonic distortion and power system imbalance. Many control systems for shunt APFs demand measurements of voltages and currents for the determination of instantaneous real and reactive power signals. From these signals, the reference currents of the shunt APF are calculated. A method of control for the APF shunt that only measures currents is proposed in this paper. The control method includes a modified technique to extract the positive and negative sequence components in the time domain. The reference currents in the shunt APF are calculated by the negative sequence components of the measured currents. Simulation and experimental results confirm the efficiency of this control scheme under ideal and non-ideal conditions.
Continuous Integrated Process of Biodiesel Production and Purification—The End of the Conventional Two-Stage Batch Process?
Authors: Bačić Matea , Ljubić Anabela , Gojun Martin , Šalić Anita , Tušek Ana Jurinjak , Zelić Bruno
Published: January 2021

In this research, optimization of the integrated biodiesel production process composed of transesterification of edible sunflower oil, catalyzed by commercial lipase, with simultaneous extraction of glycerol from the reaction mixture was performed. Deep eutectic solvents (DESs) were used in this integrated process as the reaction and extraction media. For two systems, choline chloride:glycerol (ChCl:Gly) and choline chloride:ethylene glycol (ChCl:EG), respectively, the optimal water content, mass ratio of the phase containing the mixture of reactants (oil and methanol) with an enzyme and a DES phase (mass ratio of phases), and the molar ratio of deep eutectic solvent constituents were determined using response surface methodology (RSM). Experiments performed with ChCl:Gly resulted in a higher biodiesel yield and higher glycerol extraction efficiency, namely, a mass ratio of phases of 1:1, a mass fraction of water of 6.6%, and a molar ratio of the ChCl:Gly of 1:3.5 were determined to be the optimal process conditions. When the reaction was performed in a batch reactor under the optimal conditions, the process resulted in a 43.54 ± 0.2% yield and 99.54 ± 0.19% glycerol extraction efficiency (t = 2 h). Unfortunately, the free glycerol content was higher than the one defined by international standards (wG > 0.02%); therefore, the process was performed in a microsystem to enhance the mass transfer. Gaining the same yield and free glycerol content below the standards (wG = 0.0019 ± 0.003%), the microsystem proved to be a good direction for future process optimization.
Bidirectional Power Sharing for DC Microgrid Enabled by Dual Active Bridge DC-DC Converter
Authors: Ríos Sara J. , Pagano Daniel J. , Lucas Kevin E.
Published: January 2021

Currently, high-performance power conversion requirements are of increasing interest in microgrid applications. In fact, isolated bidirectional dc-dc converters are widely used in modern dc distribution systems. The dual active bridge (DAB) dc-dc converter is identified as one of the most promising converter topology for the mentioned applications, due to its benefits of high power density, electrical isolation, bidirectional power flow, zero-voltage switching, and symmetrical structure. This study presents a power management control scheme in order to ensure the power balance of a dc microgrid in stand-alone operation, where the renewable energy source (RES) and the battery energy storage (BES) unit are interfaced by DAB converters. The power management algorithm, as introduced in this work, selects the proper operation of the RES system and BES system, based on load/generation power and state-of-charge of the battery conditions. Moreover, a nonlinear robust control strategy is proposed when the DAB converters are in voltage-mode-control in order to enhance the dynamic performance and robustness of the common dc-bus voltage, in addition to overcoming the instability problems that are caused by constant power loads and the dynamic interactions of power electronic converters. The simulation platform is developed in MATLAB/Simulink, where a photovoltaic system and battery system are selected as the typical RES and BES, respectively. Assessments on the performance of the proposed control scheme are conducted. Comparisons with the other control method are also provided.
The Influence of Apple, Carrot and Red Beet Pomace Content on the Properties of Pellet from Barley Straw
Authors: Chojnacki Jerzy , Zdanowicz Agnieszka , Ondruška Juraj , Šooš Ľubomír , Smuga-Kogut Małgorzata
Published: January 2021

Influence of wastes generated during juice production: apple, carrot and red beet, added to barley straw, on density of pellet mass, pellet hardness, ash content and calorific value was assessed. Dry mass content of additives in the substrate to pellet production was: 0, 10, 20 and 30% of the mixture weight. The relative humidity of the raw material was: 17.0, 19.5 and 22%. Higher percentages of additives and higher moisture content in the raw materials increased the hardness and density of the pellet. The contents of natural polymers such as lignin, hemicellulose and cellulose were determined in primary materials used to prepare substrate and in pellet. Changes in the determination of these substances was observed as a result of the granulation process.
Thermodynamic Study of a Combined Power and Refrigeration System for Low-Grade Heat Energy Source
Authors: Khatoon Saboora , Almefreji Nasser Mohammed A. , Kim Man-Hoe
Published: January 2021

This study focuses on the thermal performance analysis of an organic Rankine cycle powered vapor compression refrigeration cycle for a set of working fluids for each cycle, also known as a dual fluid system. Both cycles are coupled using a common shaft to maintain a constant transmission ratio of one. Eight working fluids have been studied for the vapor compression refrigeration cycle, and a total of sixty-four combinations of working fluids have been analyzed for the dual fluid combined cycle system. The analysis has been performed to achieve a temperature of −16 °C for a set of condenser temperatures 34 °C, 36 °C, 38 °C, and 40 °C. For the desired temperature in the refrigeration cycle, the required work input, mass flow rate, and heat input for the organic Rankine cycle were determined systematically. Based on the manifestation of performance criteria, three working fluids (R123, R134a, and R245fa) were chosen for the refrigeration cycle and two (Propane and R245fa) were picked for the organic Rankine cycle. Further, a combination of R123 in the refrigeration cycle with propane in the Rankine cycle was scrutinized for their highest efficiency value of 16.48% with the corresponding highest coefficient of performance value of 2.85 at 40 °C.
Brightness and Uniformity Perception of Virtual Corridor with Artificial Lighting Systems
Authors: Pracki Piotr , Krupiński Rafał
Published: January 2021

This article compares the brightness and uniformity perception of virtual corridor displayed on computer screens and under different surrounding conditions, between two groups of respondents. The computer simulations of 10 lighting scenarios in the empty corridor, diverse in terms of luminance distribution and lighting power density, were developed. The visual assessment of the lighting effects was carried out on the basis of surveys. The respondents assessed the brightness and uniformity of each plane and entire corridor for each scenario, using semantic differential scaling. Each person from the first group individually made their evaluations on the same computer screen placed in the experimental box. Each person from the second group made the assessments on different computer screens, and all respondents from this group made the evaluations in the computer room at the same time. A high convergence of the results between the groups was found in the assessments of brightness and uniformity perception for consecutive lighting situations. In 93.75% of cases, the same perception in brightness and uniformity between the group means was achieved. A high convergence of the results between the groups in the assessment of brightness and uniformity perception for the same lighting situations was also demonstrated.
Decomposition Characteristics of SF6 under Arc Discharge and the Effects of Trace H2O, O2, and PTFE Vapour on Its By-Products
Authors: Yang Ren , Xu Mengyuan , Yan Jing , Yang Minghao , Geng Yingsan , Liu Zhiyuan , Wang Jianhua
Published: January 2021

The research on decomposition characteristics of SF6 and its by-products have great significance to the operation, maintenance, condition assessment and fault diagnosis of power equipment. In this paper, the particle composition models of SF6, SF6/polytetrafluoroethylene (PTFE), SF6/PTFE/O2, SF6/PTFE/H2O, and SF6/PTFE/O2/H2O were established by using Gibbs free energy minimization method, and the effects of trace H2O and O2 impurities and PTFE vapour on SF6 by-products were studied by the models. In order to verify the correctness of the simulation results, a series of breaking experiments were carried out on a 40.5 kV SF6 circuit breaker, and a gas chromatograph was used to detect and analyse the SF6 by-products. It was found that when PTFE vapour is involved in the arc plasma, the main by-product after arc quenching is CF4, and the molar fractions of C2F6 and C3F8 are very low. When O2 is involved, the main by-products are SOF2, SO2 and SO2F2, and a small amount of CO and CO2 was also produced. When H2O is involved, the main by-products in simulation are SOF2, SO2 and HF, and a small amount of SO2, CO2, CO, SO2F2 and H2 was also produced. The experimental results are in good agreement with the above results.
Techno-Cost-Benefit Analysis of Biogas Production from Industrial Cassava Starch Wastewater in Thailand for Optimal Utilization with Energy Storage
Authors: Wattanasilp Chatree , Songprakorp Roongrojana , Nopharatana Annop , Khompatraporn Charoenchai
Published: January 2021

This paper applied the optimization model of the biogas utilization pathway with the biogas utilization availability assessment to examine the effect of biogas system parameters on biogas utilization. The model analyzes the biogas utilization pathway availability and maximum profit to value added and productivity in biogas from industry wastewater in Thailand. The results showed that profit and availability of biogas utilization reduce biogas loss to flare, that it entails several conversion processes. The scenario for the biogas utilization pathway and storage with biogas production technology improves. Evaluated are operation time, waste and energy demand to the cassava starch usage during the production for 50–1000 tons per day. Five mature biogas production technologies were benchmarked evaluated based on the chemical oxygen demand removal efficiency and biogas yields. Subsequently, low-, medium-, and high-pressure storages and a battery storage were considered and discussed in this paper as suitable energy storage for each desired biogas plant operation. Five biogas utilization pathways, including converting biogas into thermal energy, generating electricity, and upgrading biogas to compressed biogas, were then compared. Those improved options in the scenario select suitable biogas technologies, storage, and application for value-added, reduce the environmental problems and renewable energy production from wastewater.
Real-Gas-Flamelet-Model-Based Numerical Simulation and Combustion Instability Analysis of a GH2/LOX Rocket Combustor with Multiple Injectors
Authors: Hwang Won-Sub , Sung Bu-Kyeng , Han Woojoo , Huh Kang Y. , Lee Bok Jik , Han Hee Sun , Sohn Chae Hoon , Choi Jeong-Yeol
Published: January 2021

A large eddy simulation (LES) and combustion instability analysis are performed using OpenFOAM for the multiple shear-coaxial injector combustor DLR-BKD (in German Deutsches Zentrum für Luft–Brennkammer D, German Aerospace Center–Combustion Chamber D), which is a laboratory-scale combustor operating in a real-gas environment. The Redlich–Kwong–Peng–Robinson equation of state and steady-laminar flamelet model are adopted in the simulation to accurately capture the real-gas combustion effects. Moreover, the stable combustion under the LP4 condition is numerically analyzed, and the characteristics of the combustion flow field are investigated. In the numerical simulation of the combustion instability, the instability is generated by artificially superimposing the 1st transverse standing wave solution on the stable combustion solution. To decompose the combustion instability mode, the dynamic mode decomposition method is applied. Several combustion instability modes are qualitatively and quantitatively identified through contour plots and graphs, and the sustenance process of the limit cycle is investigated.