bluuebunny/crossref_metadata_2025 huggingface dataset:
Vaccines against COVID-19: Priority to mRNA-Based Formulations
Authors: Pascolo Steve
Published: October 2021

As of September 2021, twenty-one anti-COVID-19 vaccines have been approved in the world. Their utilization will expedite an end to the current pandemic. Besides the usual vaccine formats that include inactivated viruses (eight approved vaccines) and protein-based vaccines (four approved vaccines), three new formats have been validated: recombinant adenovirus (six approved vaccines), DNA (one approved vaccine), and messenger RNA (mRNA, two approved vaccines). The latter was the fastest (authorized in 2020 in the EU, the USA, and Switzerland). Most Western countries have reserved or use the protein vaccines, the adenovirus vaccines, and mRNA vaccines. I describe here the different vaccine formats in the context of COVID-19, detail the three formats that are chiefly reserved or used in Europe, Canada, and the USA, and discuss why the mRNA vaccines appear to be the superior format.
Identification of Tropical Plant Extracts That Extend Yeast Chronological Life Span
Authors: Kwong Mandy Mun Yee , Lee Jee Whu , Samian Mohammed Razip , Wahab Habibah A. , Watanabe Nobumoto , Ong Eugene Boon Beng
Published: October 2021

Certain plant extracts (PEs) contain bioactive compounds that have antioxidant and lifespan-extending activities on organisms. These PEs play different roles in cellular processes, such as enhancing stress resistance and modulating longevity-defined signaling pathways that contribute to longevity. Here, we report the discovery of PEs that extended chronological life span (CLS) in budding yeast from a screen of 222 PEs. We identified two PEs, the leaf extracts of Manihot esculenta and Wodyetia bifurcata that extended CLS in a dose-dependent manner. The CLS-extending PEs also conferred oxidative stress tolerance, suggesting that these PEs might extend yeast CLS through the upregulation of stress response pathways.
Relationships among Physical Self-Concept, Physical Activity and Mediterranean Diet in Adolescents from the Province of Granada
Authors: Pérez-Mármol Mariana , Chacón-Cuberos Ramón , García-Mármol Eduardo , Castro-Sánchez Manuel
Published: October 2021

The aim of the present research was to analyse the relationships among physical self-concept, physical activity engagement and Mediterranean diet adherence in a sample of 1650 secondary school students from the province of Granada. The study design was descriptive–exploratory, cross-sectional and ex post facto. Measurements were taken from a single group. The PSQ, PAQ-A and KIDMED questionnaires were used to measure diet quality. Results showed the presence of a positive relationship among all dimensions of physical self-concept and physical activity engagement, with better outcomes being achieved in this self-perception with increasing engagement in sport. With regard to diet quality and its repercussions on physical self-concept, it was highlighted that the dimensions of the general self-concept, physical attractiveness and strength tended to be more positive as quality improved. In contrast, worse outcomes were produced in those with a low-quality diet. In this way, it was deemed necessary to continue investigating psychosocial factors with the aim of clarifying the relationships with psychological factors and health indicators. This would enable the development of prevention and intervention programs focused on promoting wellbeing in adolescents.
Dynamical Downscaling of Surface Air Temperature and Wind Field Variabilities over the Southeastern Levantine Basin, Mediterranean Sea
Authors: ElBessa Mohamed , Abdelrahman Saad Mesbah , Tonbol Kareem , Shaltout Mohamed
Published: October 2021

The characteristics of near surface air temperature and wind field over the Southeastern Levantine (SEL) sub-basin during the period 1979–2018 were simulated. The simulation was carried out using a dynamical downscaling approach, which requires running a regional climate model system (RegCM-SVN6994) on the study domain, using lower-resolution climate data (i.e., the fifth generation of ECMWF atmospheric reanalysis of the global climate ERA5 datasets) as boundary conditions. The quality of the RegCM-SVN simulation was first verified by comparing its simulations with ERA5 for the studied region from 1979 to 2018, and then with the available five WMO weather stations from 2007 to 2018. The dynamical downscaling results proved that RegCM-SVN in its current configuration successfully simulated the observed surface air temperature and wind field. Moreover, RegCM-SVN was proved to provide similar or even better accuracy (during extreme events) than ERA5 in simulating both surface air temperature and wind speed. The simulated annual mean T2m by RegCM-SVN (from 1979 to 2018) was 20.9 °C, with a positive warming trend of 0.44 °C/decade over the study area. Moreover, the annual mean wind speed by RegCM-SVN was 4.17 m/s, demonstrating an annual negative trend of wind speed over 92% of the study area. Surface air temperatures over SEL mostly occurred within the range of 4–31 °C; however, surface wind speed rarely exceeded 10 m/s. During the study period, the seasonal features of T2m showed a general warming trend along the four seasons and showed a wind speed decreasing trend during spring and summer. The results of the RegCM-SVN simulation constitute useful information that could be utilized to fully describe the study area in terms of other atmospheric parameters.
Coating Characteristic of Hydroxyapatite on Titanium Substrates via Hydrothermal Treatment
Authors: Kien Pham , Quan Tran , Tuyet Anh Le
Published: October 2021

Medical pure titanium (Ti) shows excellent chemical stability and mechanical properties in clinical uses, but its initial fixation with host bone, when implanted, is usually delayed owing to the bioinert Ti surface. In this study, we fabricate the hydroxyapatite (HA)-coated titanium by three steps reactions: (1) to form an activated O2− layer by immersing Ti substrate into an alkaline solution such as NaOH; (2) the O2− bonds with Ca2+ to form Ca–O–Ti bonding, in which O plays the part of bridge materials between Ca and Ti substrate and (3) the conversion of Ca–O–Ti samples to HA-coated Ti samples by immersion into Na2HPO4 2 M at 180 °C for 48 h using hydrothermal methods. The effect of different phosphate solutions (NaH2PO4 2 M and Na2HPO4 2 M solution) and hydrothermal treatment time (24 and 48 h) on the characteristic of hydroxyapatite coating titanium substrate is also investigated using the optical microscope, thin film XRD and SEM/EDX. The HA-coated Ti samples fabricated by immersion into Na2HPO4 2 M at 180 °C for 48 h show fiber HA covering Titan substrate with a diameter varying from 0.1 to 0.3 µm. These HA-coated Ti samples can be regarded as promising multifunctional biomaterials.
Invariant-Based Safety Assessment of FPGA Projects: Conception and Technique
Authors: Kharchenko Vyacheslav , Illiashenko Oleg , Sklyar Vladimir
Published: October 2021

This paper describes a proposed method and technology of safety assessment of projects based on field programmable gate arrays (FPGA). Safety assessment is based on special invariants, e.g., properties which remain unchanged when a specified transformation is applied. A classification and examples of FPGA project invariants are provided. In the paper, two types of invariants are described. The first type of invariants used for such assessment are those which are versatile since they reflect the unchanged properties of FPGA projects, hardware description languages, etc. These invariants can be replenished as experience gained in project implementation accumulates. The second type of invariants is formed based on an analysis of the specifics of a particular FPGA project and reflects the features of the tasks to be solved, the algorithms that are implemented, the hardware FPGA chips used, and the computer-aided design tools, etc. The paper contains a description of the overall conception and particular stages of FPGA projects invariant-based safety assessment. As examples for solving some tasks (using of invariants and defect injections), the paper contains several algorithms written in the VHSIC hardware description language (VHDL). The paper summarizes the results obtained during several years of practical and theoretical research. It can be of practical use for engineers and researchers in the field of quality, reliability, and security of embedded systems, software and information management systems for critical and business applications.
Classification of Breast Cancer Lesions in Ultrasound Images by Using Attention Layer and Loss Ensemble in Deep Convolutional Neural Networks
Authors: Kalafi Elham Yousef , Jodeiri Ata , Setarehdan Seyed Kamaledin , Lin Ng Wei , Rahmat Kartini , Taib Nur Aishah , Ganggayah Mogana Darshini , Dhillon Sarinder Kaur
Published: October 2021

The reliable classification of benign and malignant lesions in breast ultrasound images can provide an effective and relatively low-cost method for the early diagnosis of breast cancer. The accuracy of the diagnosis is, however, highly dependent on the quality of the ultrasound systems and the experience of the users (radiologists). The use of deep convolutional neural network approaches has provided solutions for the efficient analysis of breast ultrasound images. In this study, we propose a new framework for the classification of breast cancer lesions with an attention module in a modified VGG16 architecture. The adopted attention mechanism enhances the feature discrimination between the background and targeted lesions in ultrasound. We also propose a new ensembled loss function, which is a combination of binary cross-entropy and the logarithm of the hyperbolic cosine loss, to improve the model discrepancy between classified lesions and their labels. This combined loss function optimizes the network more quickly. The proposed model outperformed other modified VGG16 architectures, with an accuracy of 93%, and also, the results are competitive with those of other state-of-the-art frameworks for the classification of breast cancer lesions. Our experimental results show that the choice of loss function is highly important and plays a key role in breast lesion classification tasks. Additionally, by adding an attention block, we could improve the performance of the model.
Surgical versus Transvalvular Aortic Valve Replacement in Elderly Patients—The Impact of Frailty
Authors: Oancea Andra , Furnică Cristina , Chistol Raluca Ozana , Mitu Florin , Leon-Constantin Maria-Magdalena , Tinică Grigore
Published: October 2021

(1) Background: The aging process leads to an increased number of patients with cardiovascular diseases that require surgical treatment. One of the most common heart diseases with an increased prevalence in the elderly is aortic stenosis (AS). Recently, transcatheter aortic valve implantation (TAVI) has become the preferred technique for frail patients with high surgical risk. Currently, there is no gold standard method for assessing frailty. The available scores are objective, but limited by the lack of prospective information, especially from patients undergoing cardiac surgery or interventional procedures. Moreover, the current frailty scores record only certain aspects of the frailty identified in some system and organs. The aims of this study were to evaluate the different profile patients treated with TAVI or with surgical aortic valve replacement (SAVR) and to analyze the risk factors of unfavorable outcomes in the two groups to identify potential factors for frailty that could be included in the new scoring system. (2) Methods: This study included patients over 65 years old evaluated with severe, symptomatic AS treated with TAVI or SAVR admitted to the Cardiovascular Diseases Institute, Iasi. (3) Results: The group included 88 patients treated with TAVI compared with 218 patients undergoing SAVR. Most of the TAVI patients (84.09%) were over 70 years compared to 30.09% of the SAVR group. The TAVI patients had an increased surgical risk assessed by EuroSCORE II (15 vs. 4%) and severe heart failure (NYHA IV, 36.36 vs. 6.48%). The only residual symptom was dyspnea, in a significantly lower prevalence compared to preoperative evaluation. (4) Conclusions: TAVI improves the general status with results comparable to SAVR in elderly patients with increased severity of the disease and higher prevalence of comorbidities.
A Machine Learning Approach for Chronic Heart Failure Diagnosis
Authors: Plati Dafni K. , Tripoliti Evanthia E. , Bechlioulis Aris , Rammos Aidonis , Dimou Iliada , Lakkas Lampros , Watson Chris , McDonald Ken , Ledwidge Mark , Pharithi Rebabonye , Gallagher Joe , Michalis Lampros K. , Goletsis Yorgos , Naka Katerina K. , Fotiadis Dimitrios I.
Published: October 2021

The aim of this study was to address chronic heart failure (HF) diagnosis with the application of machine learning (ML) approaches. In the present study, we simulated the procedure that is followed in clinical practice, as the models we built are based on various combinations of feature categories, e.g., clinical features, echocardiogram, and laboratory findings. We also investigated the incremental value of each feature type. The total number of subjects utilized was 422. An ML approach is proposed, comprising of feature selection, handling class imbalance, and classification steps. The results for HF diagnosis were quite satisfactory with a high accuracy (91.23%), sensitivity (93.83%), and specificity (89.62%) when features from all categories were utilized. The results remained quite high, even in cases where single feature types were employed.
Computed Tomography Angiography (CTA) before Reconstructive Jaw Surgery Using Fibula Free Flap: Retrospective Analysis of Vascular Architecture
Authors: Knitschke Michael , Baumgart Anna Katrin , Bäcker Christina , Adelung Christian , Roller Fritz , Schmermund Daniel , Böttger Sebastian , Howaldt Hans-Peter , Attia Sameh
Published: October 2021

Computed tomography angiography (CTA) is widely used in preoperative evaluation of the lower limbs’ vascular system for virtual surgical planning (VSP) of fibula free flap (FFF) for jaw reconstruction. The present retrospective clinical study analysed n = 72 computed tomography angiographies (CTA) of lower limbs for virtual surgical planning (VSP) for jaw reconstruction. The purpose of the investigation was to evaluate the morphology of the fibular bone and its vascular supply in CTA imaging, and further, the amount and distribution of periosteal branches (PB) and septo-cutaneous perforators (SCPs) of the fibular artery. A total of 144 lower limbs was assessed (mean age: 58.5 ± 15.3 years; 28 females, 38.9%; 44 males, 61.1%). The vascular system was categorized as regular (type I-A to II-C) in 140 cases (97.2%) regarding the classification by Kim. Absent anterior tibial artery (type III-A, n = 2) and posterior tibial artery (type III-B, n = 2) were detected in the left leg. Stenoses were observed mostly in the fibular artery (n = 11), once in the anterior tibial artery, and twice in the posterior tibial artery. In total, n = 361 periosteal branches (PBs) and n = 231 septo-cutaneous perforators (SCPs) were recorded. While a distribution pattern for PBs was separated into two clusters, a more tripartite distribution pattern for SCPs was found. We conclude that conventional CTA for VSP of free fibula flap (FFF) is capable of imaging and distinguishing SCPs and PBs.
Computational Fluid Dynamic Technique for Assessment of How Changing Character of Blood Flow and Different Value of Hct Influence Blood Hemodynamic in Dissected Aorta
Authors: Polanczyk Andrzej , Piechota-Polanczyk Aleksandra , Huk Ihor , Neumayer Christoph , Balcer Julia , Strzelecki Michal
Published: October 2021

Using computer tomography angiography (CTA) and computational structural analysis, we present a non-invasive method of mass flow rate/velocity and wall stress analysis in type B aortic dissection. Three-dimensional (3D) computer models of the aorta were calculated using pre-operative (baseline) and post-operative CT data from 12 male patients (aged from 51 to 64 years) who were treated for acute type B dissection. A computational fluid dynamics (CFD) technique was used to quantify the displacement forces acting on the aortic wall in the areas of endografts placement. The mass flow rate and wall stress were measured and quantified using the CFD technique. The CFD model indicated the places with a lower value of blood velocity and shear rate, which corelated with higher blood viscosity and a probability of thrombus appearance. Moreover, with the increase in Hct, blood viscosity also increased, while the intensity of blood flow provoked changing viscosity values in these areas. Furthermore, the velocity gradient near the tear surface caused high wall WSS; this could lead to a decreased resistance in the aorta’s wall with further implications to a patient.
Diagnostic Value of PET/MR with DWI for Burkitt Lymphoma
Authors: Giraudo Chiara , Simeone Rossella , Fosio Margherita , Marino Dario , Cecchin Diego
Published: October 2021

18F-FDG-PET/MR images, including DWI, of a 46-year-old male admitted to the Emergency Room of our tertiary center, who was suffering from diplopia, left orbital pain, and a headache for two weeks, demonstrated multiple hepatic nodules, a pancreatic mass, and skeletal metastases, in addition to thrombosis of the left cavernous sinus, thickening of the small intestine, and a large hepatic lesion identified at head and neck MR and whole-body CT, respectively. Hepatic and bone marrow biopsies revealed the diagnosis of Burkitt lymphoma. After four cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, methotrexate/ifosfamide, etoposide, and high dose cytarabine (R- CODOX-M/IVAC), a complete metabolic response occurred.
The Fracture Resistance of Additively Manufactured Monolithic Zirconia vs. Bi-Layered Alumina Toughened Zirconia Crowns When Cemented to Zirconia Abutments. Evaluating the Potential of 3D Printing of Ceramic Crowns: An In Vitro Study
Authors: Zandinejad Amirali , Revilla-León Marta , Methani Mohammad Mujtaba , Nasiry Khanlar Leila , Morton Dean
Published: October 2021

(1) Background: This study compared the fracture resistance of additively manufactured monolithic zirconia and bi-layered alumina toughened zirconia crowns on implants. (2) Methods: Maxillary model with a dental implant replacing right second bicuspid was obtained. Custom abutments and full-contour crowns for additively manufactured monolithic zirconia and bi-layered alumina reinforced zirconia crowns (n = 10) were fabricated. The crowns were cemented to implant-supported zirconia abutments and the assembly fixed onto resin blocks. Fracture resistance was measured using a universal testing machine at a crosshead speed of 2 mm/min. A Kruskal–Wallis test was used to analyze the data. (3) Results: Although additively manufactured monolithic zirconia crowns demonstrated a higher mean fracture resistance than bi-layered alumina toughened zirconia crowns, statistical analysis revealed no significant difference in fracture resistance between the two groups. All specimens fractured at the implant–abutment interface. (4) Conclusions: Additively manufactured bi-layered alumina toughened zirconia crowns demonstrated similar fracture resistance to additively manufactured monolithic zirconia crowns when cemented to implant-supported zirconia abutments.
Deep Coupling Recurrent Auto-Encoder with Multi-Modal EEG and EOG for Vigilance Estimation
Authors: Song Kuiyong , Zhou Lianke , Wang Hongbin
Published: October 2021

Vigilance estimation of drivers is a hot research field of current traffic safety. Wearable devices can monitor information regarding the driver’s state in real time, which is then analyzed by a data analysis model to provide an estimation of vigilance. The accuracy of the data analysis model directly affects the effect of vigilance estimation. In this paper, we propose a deep coupling recurrent auto-encoder (DCRA) that combines electroencephalography (EEG) and electrooculography (EOG). This model uses a coupling layer to connect two single-modal auto-encoders to construct a joint objective loss function optimization model, which consists of single-modal loss and multi-modal loss. The single-modal loss is measured by Euclidean distance, and the multi-modal loss is measured by a Mahalanobis distance of metric learning, which can effectively reflect the distance between different modal data so that the distance between different modes can be described more accurately in the new feature space based on the metric matrix. In order to ensure gradient stability in the long sequence learning process, a multi-layer gated recurrent unit (GRU) auto-encoder model was adopted. The DCRA integrates data feature extraction and feature fusion. Relevant comparative experiments show that the DCRA is better than the single-modal method and the latest multi-modal fusion. The DCRA has a lower root mean square error (RMSE) and a higher Pearson correlation coefficient (PCC).
A Novel Feature Extraction Method for Power Transformer Vibration Signal Based on CEEMDAN and Multi-Scale Dispersion Entropy
Authors: Shang Haikun , Xu Junyan , Li Yucai , Lin Wei , Wang Jinjuan
Published: October 2021

Effective diagnosis of vibration fault is of practical significance to ensure the safe and stable operation of power transformers. Aiming at the traditional problems of transformer vibration fault diagnosis, a novel feature extraction method based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and multi-scale dispersion entropy (MDE) was proposed. In this paper, CEEMDAN method is used to decompose the original transformer vibration signal. Additionally, then MDE is used to capture multi-scale fault features in the decomposed intrinsic mode functions (IMFs). Next, the principal component analysis (PCA) method is employed to reduce the feature dimension and extract the effective information in vibration signals. Finally, the simplified features are sent into density peak clustering (DPC) to get the fault diagnosis results. The experimental data analysis shows that CEEMDAN-MDE can effectively extract the information of the original vibration signals and DPC can accurately diagnose the types of transformer faults. By comparing different algorithms, the practicability and superiority of this proposed method are verified.
Brazilian and Spanish Mathematics Teachers’ Predispositions towards Gamification in STEAM Education
Authors: López Paula , Rodrigues-Silva Jefferson , Alsina Ángel
Published: October 2021

This article reports a multiple case study in which we analyse Brazilian and Spanish mathematics teachers’ opinions about and predispositions toward gamified activities in STEAM education. To obtain data, we administered a survey to 56 in-service mathematics teachers in primary and secondary education from these countries. The survey had been previously validated throughout an expert judgement process. Our results show a high percentage of teachers who think this kind of activity has positive effects on students’ development, improving their affective domain toward mathematics and required skills for mathematical competency. Notwithstanding, many teachers report insecurity and lack of training for employing such educational methodologies.
A 6 GHz Integrated High-Efficiency Class-F−1 Power Amplifier in 65 nm CMOS Achieving 47.8% Peak PAE
Authors: Ali Syed Muhammad Ammar , Hasan S. M. Rezaul
Published: October 2021

This paper reports a “single-transistor” Class-F−1 power amplifier (PA) in 65 nm CMOS, which operates at the microwave center frequency of 6 GHz. The PA is loaded with a Class-F−1 harmonic control network, employing a new “parasitic-aware” topology deduced using a novel iterative algorithm. A dual-purpose output matching network is designed, which not only serves the purpose of output impedance matching, but also reinforces the harmonic control of the Class-F−1 harmonic network. This proposed PA yields a peak power-added efficiency (PAE) of 47.8%, which is one of the highest when compared to previously reported integrated microwave/millimeter-wave PAs in CMOS and SiGe technologies. The amplifier shows a saturated output power of 14.4 dBm along with an overall gain of 13.8 dB.
Data-Driven Deep Learning-Based Attention Mechanism for Remaining Useful Life Prediction: Case Study Application to Turbofan Engine Analysis
Authors: Muneer Amgad , Taib Shakirah Mohd , Naseer Sheraz , Ali Rao Faizan , Aziz Izzatdin Abdul
Published: October 2021

Accurately predicting the remaining useful life (RUL) of the turbofan engine is of great significance for improving the reliability and safety of the engine system. Due to the high dimension and complex features of sensor data in RUL prediction, this paper proposes four data-driven prognostic models based on deep neural networks (DNNs) with an attention mechanism. To improve DNN feature extraction, data are prepared using a sliding time window technique. The raw data collected after normalizing is simply fed into the suggested network, requiring no prior knowledge of prognostics or signal processing and simplifying the proposed method’s applicability. In order to verify the RUL prediction ability of the proposed DNN techniques, the C-MAPSS benchmark dataset of the turbofan engine system is validated. The experimental results showed that the developed long short-term memory (LSTM) model with attention mechanism achieved accurate RUL prediction in both scenarios with a high degree of robustness and generalization ability. Furthermore, the proposed model performance outperforms several state-of-the-art prognosis methods, where the LSTM-based model with attention mechanism achieved an RMSE of 12.87 and 11.23 for FD002 and FD003 subset of data, respectively.
A Low Latency Secure Communication Architecture for Microgrid Control
Authors: Kondoro Aron , Dhaou Imed , Tenhunen Hannu , Mvungi Nerey
Published: October 2021

The availability of secure, efficient, and reliable communication systems is critical for the successful deployment and operations of new power systems such as microgrids. These systems provide a platform for implementing intelligent and autonomous algorithms that improve the power control process. However, building a secure communication system for microgrid purposes that is also efficient and reliable remains a challenge. Conventional security mechanisms introduce extra processing steps that affect performance by increasing the latency of microgrid communication beyond acceptable limits. They also do not scale well and can impact the reliability of power operations as the size of a microgrid grows. This paper proposes a low latency secure communication architecture for control operations in an islanded IoT-based microgrid that solves these problems. The architecture provides a secure platform that optimises the standard CoAP/DTLS implementation to reduce communication latency. It also introduces a traffic scheduler component that uses a fixed priority preemptive algorithm to ensure reliability as the microgrid scales up. The architecture is implemented on a lab-scale IoT-based microgrid prototype to test for performance and security. Results show that the proposed architecture can mitigate the main security threats and provide security services necessary for power control operations with minimal latency performance. Compared to other implementations using existing secure IoT protocols, our secure architecture was the only one to satisfy and maintain the recommended latency requirements for power control operations, i.e., 100 ms under all conditions.
Development and Analysis of a Dynamic Energy Model of an Office Using a Building Management System (BMS) and Actual Measurement Data
Authors: Džiugaitė-Tumėnienė Rasa , Mikučionienė Rūta , Streckienė Giedrė , Bielskus Juozas
Published: October 2021

Calibration of the energy model of a building is one of the essential tasks required to determine the efficiency of building management systems, and both their own and other systems’ improvement potential. In order to make the building energy model as accurate as possible, it is necessary to collect comprehensive data on its operation and sometimes to assess the missing information. This paper represents the process of developing an energy model for an administrative building and its calibration procedure, using detailed long-term measurement and building management system (BMS) data. Indoor air temperature, CO₂ concentration, and relative humidity were experimentally measured and evaluated separately. Such dual application of data reduces the inaccuracy of the assumptions made and assesses the model’s accuracy. The DesignBuilder software developed the building model. During the development of the model, it was observed that the actual energy consumption needs to be assessed, as the assumptions made during the design about the operation and management of HVAC systems often do not coincide with the actual situation. After integrating BMS information on HVAC management into the building model, the resulting discrepancy between the model results and the actual heat consumption was 6.5%. Such a model can be further used to optimize management decisions and assess energy savings potential.
Global Sensitivity Analysis Applied to Train Traffic Rescheduling: A Comparative Study
Authors: Saad Soha , Ossart Florence , Bigeon Jean , Sourdille Etienne , Gance Harold
Published: October 2021

The adjustment of rail traffic in the event of an electrical infrastructure disruption presents an important decision-making process for the smooth operation of the network. Railway systems are complex, and their analysis relies on expensive simulations, which makes incident management difficult. This paper proposes the use of sensitivity analysis in order to evaluate the influence of different traffic adjustment actions (e.g., spacing between trains and speed reduction) on the train supply voltage, which must never drop below the critical value prescribed by technical standards. Three global sensitivity analysis methods dedicated to black box, multivariate, nonlinear models are considered: generalized Sobol indices, energy distance-based indices, and regional sensitivity analysis. The three methods are applied to a simple traffic rescheduling test case and give similar results, but at different costs. Regional sensitivity analysis appears to be the most suitable method for the present application: it is easy to implement, rather fast, and accounts for constraints on the system output (a key feature for electrical incident management). The application of this method to a test case representative of a real rescheduling problem shows that it provides the information needed by the traffic manager to reschedule traffic in an efficient way. The same type of approach can be used for any power system optimization problem with the same characteristics.
Operation Strategy of Electricity Retailers Based on Energy Storage System to Improve Comprehensive Profitability in China’s Electricity Spot Market
Authors: Lu Ting , Zhang Weige , Ding Xiaowei
Published: October 2021

Due to the development of China’s electricity spot market, the peak-shifting operation modes of energy storage devices (ESD) are not able to adapt to real-time fluctuating electricity prices. The settlement mode of the spot market aggravates the negative impact of deviation assessments on the cost of electricity retailers. This article introduces the settlement rules of China’s power spot market. According to the electricity cost settlement process and the assessment methods, this paper proposes a comprehensive electricity cost optimization algorithm that optimizes day-ahead market (DA) electricity cost, real-time market (RT) electricity cost and deviation assessment through ESD control. According to the trial electricity price data of the power trading center in Guangdong province (China), many typical load curves and different deviation assessment policies, the algorithm calculates DA electricity cost, RT electricity cost and deviation assessment cost by utilizing a comprehensive electricity cost optimization algorithm. Compared with the original electricity cost and optimization cost, this method is proven to effectively save overall electricity costs under the spot market settlement system. Based on three different initial investment prices of ESD, this paper analyzes the economics of the ESD system and proves that ESD investment can be recovered within 5 years. Considering the small amounts of operating data in China’s power spot market, the algorithm generates random data according to characteristics of these data. Then, this paper verifies that the comprehensive electricity cost optimization algorithm remains reliable under random circumstances.
An Extensive Study on Desorption Models Generated Based on Langmuir and Knudsen Diffusion
Authors: Alkuwaiti Hamda , Belhaj Hadi , Aldhuhoori Mohammed , Ghosh Bisweswar , Fernandes Ryan
Published: October 2021

Although gas desorption is a known phenomenon, modeling fluid flow in tight gas reservoirs often ignores the governing desorption effect, assuming that viscous transport is the predominant controller, resulting in an erroneous prediction of mass transport and fluid flow calculations. Thus, developing a new model accommodating all the major contributing forces in such a medium is essential. This work introduces a new comprehensive flow model suitable for tight unconventional reservoirs, including viscous, inertia, diffusion, and sorption forces, to account for fluid transport. Based on Langmuir law and Knudsen diffusion effect, three models were generated and compared with different known models using synthetic data. The model was solved and analyzed for different scenario cases, and parametric studies were conducted to evaluate the desorption effect on different reservoir types using MATLAB. Results show that the contribution of the sorption mechanism to the flow increases with the reducing permeability of the medium and lower viscosity of the flowing fluid and an additional pressure drop up to 10 psi was quantified.
Estimating the Smart Readiness Indicator in the Italian Residential Building Stock in Different Scenarios
Authors: Canale Laura , De Monaco Marianna , Di Pietra Biagio , Puglisi Giovanni , Ficco Giorgio , Bertini Ilaria , Dell’Isola Marco
Published: October 2021

The Energy Performance of Buildings Directive 2018/844/EU introduced the smart readiness indicator (SRI) to provide a framework to evaluate and promote building smartness in Europe. In order to establish a methodological framework for the SRI calculation, two technical studies were launched, at the end of which a consolidated methodology to calculate the SRI of a building basing on a flexible and modular multicriteria assessment has been proposed. In this paper the authors applied the above-mentioned methodology to estimate the SRI of the Italian residential building stock in different scenarios. To this end, eight “smart building typologies”, representative of the Italian residential building stock, have been identified. For each smart building typology, the SRI was calculated in three scenarios: (a) base scenario (building stock as it is); (b) an “energy scenario” (simple energy retrofit) and (c) a “smart energy scenario” (energy retrofit from a smart perspective). It was therefore possible to estimate a national average SRI value of 5.0%, 15.7%, and 27.5% in the three above defined scenarios, respectively.
Heat Loss Due to Domestic Hot Water Pipes
Authors: Hamburg Anti , Mikola Alo , Parts Tuule-Mall , Kalamees Targo
Published: October 2021

Domestic hot water (DHW) system energy losses are an important part of energy consumption in newly built or in reconstructed apartment buildings. To reach nZEB or low energy building targets (renovation cases) we should take these losses into account during the design phase. These losses depend on room and water temperature, insulation and length of pipes and water circulation strategy. The target of our study is to develop a method which can be used in the early stages of design in primary energy calculations. We are also interested in how much of these losses cannot be utilised as internal heat gain and how much heat loss depends on the level of energy performance of the building. We used detailed DHW system heat loss measurements and simulations from an nZEB apartment building and annual heat loss data from a total of 22 apartment buildings. Our study showed that EN 15316-3 standard equations for pipe length give more than a twice the pipe length in basements. We recommend that for pipe length calculation in basements, a calculation based on the building’s gross area should be used and for pipe length in vertical shafts, a building’s heating area-based calculation should be used. Our study also showed that up to 33% of pipe heat losses can be utilised as internal heat gain in energy renovated apartment buildings but in unheated basements this figure drops to 30% and in shafts rises to 40% for an average loss (thermal pipe insulation thickness 40 mm) of 10.8 W/m and 5.1 W/m. Unutilised delivered energy loss from DHW systems in smaller apartment buildings can be up to 12.1 kWh/(m2·a) and in bigger apartment buildings not less than 5.5 kWh/(m2·a) (40 mm thermal pipe insulation).
Numerical Study on Optics and Heat Transfer of Solar Reactor for Methane Thermal Decomposition
Authors: Kim Haneol , Kim Jongkyu
Published: October 2021

This study aims to reduce greenhouse gas emissions to the atmosphere and effectively utilize wasted resources by converting methane, the main component of biogas, into hydrogen. Therefore, a reactor was developed to decompose methane into carbon and hydrogen using solar thermal sources instead of traditional energy sources, such as coal and petroleum. The optical distributions were analyzed using TracePro, a Monte Carlo ray-tracing-based program. In addition, Fluent, a computational fluid dynamics program, was used for the heat and mass transfer, and chemical reaction. The cylindrical indirect heating reactor rotates at a constant speed to prevent damage by the heat source concentrated at the solar furnace. The inside of the reactor was filled with a porous catalyst for methane decomposition, and the outside was surrounded by insulation to reduce heat loss. The performance of the reactor, according to the cavity model, was calculated when solar heat was concentrated on the reactor surface and methane was supplied into the reactor in an environment with a solar irradiance of 700 W/m2, wind speed of 1 m/s, and outdoor temperature of 25 °C. As a result, temperature, methane mass fraction distribution, and heat loss amounts for the two cavities were obtained, and it was found that the effect on the conversion rate was largely dependent on a temperature over 1000 °C in the reactor. Moreover, the heat loss of the full-cavity model decreased by 12.5% and the methane conversion rate increased by 33.5%, compared to the semi-cavity model. In conclusion, the high-temperature environment of the reactor has a significant effect on the increase in conversion rate, with an additional effect of reducing heat loss.
Performance and Exhaust Emissions of a Spark Ignition Internal Combustion Engine Fed with Butanol–Glycerol Blend
Authors: Szwaja Stanislaw , Gruca Michal , Pyrc Michal , Juknelevičius Romualdas
Published: October 2021

Investigation of a new type of fuel for the internal combustion engine, which can be successfully used in both the power generation and the automotive industries, is presented in this article. The proposed fuel is a blend of 75% n-butanol and 25% glycerol. The engine tests conducted with this glycerol–butanol blend were focused on the performance, combustion thermodynamics, and exhaust emissions of a spark-ignition engine. A comparative analysis was performed to find potential similarities and differences in the engine fueled with gasoline 95 and the proposed glycerol–butanol blend. As measured, CO exhaust emissions increased, NOx emissions decreased, and UHC emissions were unchanged for the glycerol–butanol blend when compared to the test with sole gasoline. As regards the engine performance and combustion progress, no significant differences were observed. Exhaust temperature remarkably decreased by 3.4%, which contributed to an increase in the indicated mean effective pressure by approximately 4% compared to gasoline 95. To summarize, the proposed glycerol–butanol blend can be directly used as a replacement for gasoline in internal combustion spark-ignition engines.
Web-Based Toolkit for Performance Simulation and Analysis of Power Line Communication Networks
Authors: Sanz Mario , Moreno José Ignacio , López Gregorio , Matanza Javier , Berrocal Julio
Published: October 2021

AMIs (Advanced Metering Infrastructures) present an important role in Smart City environments, especially from the point of view of distribution and customers, offering control and monitoring capabilities. The use of PLC (Power Line Communication) technology offers a wide range of advantages in AMI, including not needing to deploy an additional communication infrastructure. However, the electrical network was not initially designed for communications, as these networks pose problems depending on the connected loads, such as network impedance variation, frequency selectivity or noise. For this reason, the use of simulators is proposed to facilitate the deployments based on PLC networks, and analysis and diagnosis tools for the identification of problems in operating networks are also required. This paper presents a toolkit for evaluating and analyzing the performance of PLC networks. This toolkit is composed of SimPRIME, a simulator for the evaluation of NB-PLC PRIME (PoweR line Intelligent Metering Evolution) networks’ performance; SimBPL, a simulator for the evaluation of MV-BPL (Broadband Power Line over Medium Voltage) cells’ performance; and PRIME Analytics, a forensics tool that allows diagnosis of communication problems in PRIME operational networks based on traffic traces. The toolkit has been developed throughout several research projects in close collaboration with DSOs (Distribution System Operators) and equipment manufacturers, so they provide solutions to actual problems of these industry key players and have been adapted to facilitate their use. As a result, the tools are accessible through web applications to increase their usability, portability, and scalability. These applications represent the first steps in offering PLC simulation and analysis as a service that could benefit the research community, academia, and industry.
A New Concept of Air Cooling and Heat Pipe for Electric Vehicles in Fast Discharging
Authors: Behi Hamidreza , Kalogiannis Theodoros , Suresh Patil Mahesh , Mierlo Joeri Van , Berecibar Maitane
Published: October 2021

This paper presents the concept of a hybrid thermal management system (TMS) including natural convection, heat pipe, and air cooling assisted heat pipe (ACAH) for electric vehicles. Experimental and numerical tests are described to predict the thermal behavior of a lithium titanate oxide (LTO) battery cell in a fast discharging process (8C rate). Specifications of different cooling techniques are deliberated and compared. The mathematical models are solved by COMSOL Multiphysics® (Stockholm, Sweden), the commercial computational fluid dynamics (CFD) software. The simulation results are validated against experimental data with an acceptable error range. The results specify that the maximum cell temperatures for the cooling systems of natural convection, heat pipe, and ACAH reach 56, 46.3, and 38.3 °C, respectively. We found that the maximum cell temperature experiences a 17.3% and 31% reduction with the heat pipe and ACAH, respectively, compared with natural convection.
Heat Transfer and Bearing Characteristics of Energy Piles: Review
Authors: Xie Jinli , Qin Yinghong
Published: October 2021

Energy piles, combined ground source heat pumps (GSHP) with the traditional pile foundation, have the advantages of high heat transfer efficiency, less space occupation and low cost. This paper summarizes the latest research on the heat transfer and bearing capacity of energy piles. It is found that S-shaped tubes have the largest heat transfer area and the best heat transfer efficiency; that energy piles need to be designed conservatively, such as adjusting the safety coefficient, number and spacing of the piles according to the additional temperature loads; and that unbalanced surface temperature has not been resolved, caused by uneven refrigeration/heating demand in one cycle. A composite energy pile applied to water-rich areas is proposed to overcome the decay of bearing and heat transfer performance. Besides, most of the heat transfer models are borehole-oriented and will fit for energy piles effectively if the models support variable ground temperature boundary conditions.
Wake Shape and Height Profile Measurements in a Concave Open Channel Flow regarding the Target in DONES
Authors: Brenneis Björn , Gordeev Sergej , Ruck Sebastian , Stoppel Leonid , Hering Wolfgang
Published: October 2021

Wakes appearing downstream of disturbances on the surface of a water flow in a concave open channel were examined experimentally. The investigated channel geometry was similar to the liquid lithium target in DONES (Demonstration fusion power plant Oriented NEutron Source). The objective of the measurements was to analyze the effect of a disturbance on the downstream layer thickness. For measuring the height profiles in the channel, an optical measurement system based on laser triangulation was developed. It was shown that the wake of the undisturbed flow emerged from the nozzle corner, which was in accordance with analytical solutions. For sufficiently large disturbances at the nozzle edge, the height profiles located downstream showed symmetrical minima and maxima on both sides of the disturbance. The wake depth strongly depended on the diameter and penetration depth of the disturbance, as well as the circumferential position in the channel, which yields to a critical wake depth of one millimeter for the lithium target in DONES.
Ab-Initio Molecular Dynamics Simulation of Condensed-Phase Reactivity: The Electrolysis of Ammonia and Ethanimine in Aquatic Carbon Dioxide Solutions
Authors: Gordiy Igor , Steinbach Lukas , Frank Irmgard
Published: October 2021

The re-use of wastewater is an increasingly important subject. Most recently, several attempts were reported to convert wastewater in harmless or even valuable substances by the use of electrical current. Electrochemistry is an old approach. The renewed interest stems from the fact that electrical current is often available in abundance, for example from solar energy in arid regions, while clean water is not. Experimentally, one has to deal with very many products which are the result of many reaction steps. Here, theory can help. Using Car–Parrinello molecular dynamics, we simulate the first few reaction steps of the electrolysis of wastewater. On the basis of previous studies, we investigate the reaction of carbon dioxide and nitrogen compounds. The results show a great variety of reaction steps and resulting products. Some of them are technologically interesting, such as hydrogen and formic acid.
Secrets of the Astute Red Fox (Vulpes vulpes, Linnaeus, 1758): An Inside-Ecosystem Secret Agent Serving One Health
Authors: Garcês Andreia , Pires Isabel
Published: October 2021

An ecosystem’s health is based on a delicate balance between human, nonhuman animal, and environmental health. Any factor that leads to an imbalance in one of the components results in disease. There are several bioindicators that allow us to evaluate the status of ecosystems. The red fox (Vulpes vulpes, Linnaeus, 1758) has the widest world distribution among mammals. It is highly adaptable, lives in rural and urban areas, and has a greatly diverse diet. Being susceptible to environmental pollution and zoonotic agents, red foxes may act as sentinels to detect environmental contaminants, climatic changes and to prevent and control outbreaks of emerging or re-emerging zoonosis. This paper aims to compile the latest information that is related to the red fox as a sentinel of human, animal, and environmental health.