bluuebunny/crossref_metadata_2025 huggingface dataset:
Experiences of Social Participation for Canadian Wheelchair Users with Spinal Cord Injury during the First Wave of the COVID-19 Pandemic
Authors: Fortin-Bédard Noémie , de Serres-Lafontaine Annabelle , Best Krista L. , Rahn Caroline , Turcotte Elizabeth , Borisoff Jaimie , Sweet Shane N. , Arbour-Nicitopoulos Kelly P. , Routhier François
Published: July 2022

The COVID-19 pandemic caused drastic life changes for people with spinal cord injury (SCI). The objective of the study is to explore the social participation of Canadian wheelchair users with SCI during the first wave of COVID-19. Methods: Fourteen participants from Quebec and British Columbia participated in a multi methods cross-sectional study. Three themes were identified, including (1) perceived participation restrictions for people with SCI and their loved ones, which revealed interruptions and changes in service provision during COVID-19, barriers and inconveniences to maintaining life habits and strategies developed during the pandemic to continue participating in meaningful activities; (2) There was no change in life habits (but some subjects found new ways to perform some activities), which highlights that life simply continued as usual and the participants developed new pastimes and interests; and (3) future hopes and concerns, which explained participants’ concerns about changes in interpersonal relationships after the pandemic. This study highlights daily participation challenges for people with SCI during the pandemic. Even though the use of technologies, delivery services and social support seemed to facilitate engagement in meaningful activities, mental health challenges and concerns for future relationships persisted for some.
Does the Length of Mini Dental Implants Affect Their Resistance to Failure by Overloading?
Authors: Alshenaiber Rafif , Silikas Nick , Barclay Craig
Published: July 2022

Objective: We aimed to evaluate the failure resistance of different lengths of mini dental implants from the same manufacturer, and to assess their failure following overloading. Materials and Methods: According to the ISO 14801, 15 mini dental implants 2.4 mm in diameter, with lengths of 8.5 mm, 10 mm, or 13 mm, were subjected to compression loading until failure using a universal testing machine. The mean load-to-failure values for each length of the mini dental implants were calculated and analysed using SPSS®, via one-way ANOVA (p < 0.05). Results: The mean load to failure for mini dental implants was 329 N (SD 6.23), 326 N (SD 5.95), and 325 N (SD 6.99) for the 13 mm, 10 mm, and 8.5 mm implants, respectively. A comparison of means showed no significant difference between the groups (p = 0.70). The tested mini dental implants exhibited bending failure modes below the first thread. Conclusion: Under high compressive loading testing, there was no effect of the length on the failure of the mini dental implants following overloading. Moreover, all tested mini dental implants with different lengths showed the same failure mode and distortion location.
Oral Microbiome Profiles and Inflammation in Pregnant Women Who Used Orthodontic Appliances
Authors: Kurniawan Fajar Kusuma Dwi , Roestamadji Retno Indrawati , Takahashi Nobuhiro , Tedjosasongko Udijanto , Narmada Ida Bagus , Surboyo Meircurius Dwi Condro , Diyatri Indeswati
Published: July 2022

It is common for women to undergo orthodontic treatment during pregnancy, especially through the use of fixed orthodontic devices. In changing the oral microbiome profile, it is crucial to increase the immune responses of pregnant women using fixed orthodontics; however, changes in the microbiomes of pregnant women with orthodontic appliances can be adjusted. Therefore, we aimed to conduct research on the oral cavity microbiome profiles, specifically IL-6 and TNF-α, of pregnant women using fixed orthodontic appliances. We proposed an observational analysis of 30 third-trimester pregnant women. OHI-S was recorded, saliva collection was performed using the passive drool method for IL-6 and TNF-α, and analysis and mucosal swabs were used to determine the oral microbiome profile. Kruskal–Wallis and post hoc Bonferroni tests were used to identify any significant differences with values of p < 0.05. Of these pregnant women, those with orthodontic appliances developed 10 types of bacteria at similar levels (>80%) from the genera Streptococcus, Lactobacillus, and Veillonella. There was no difference between the oral microbiomes of the control group and the pregnant women with a history of orthodontic appliance use. While the level of TNF-α in the women with orthodontic appliances was higher compared with the control group who had never used orthodontic appliances (p < 0.05), there was no difference in the IL-6 levels. The IL-6 and microbiome profile produced normal results, so the use of orthodontic appliances during pregnancy should be allowed with conditions. Pregnant women with orthodontic appliances must keep the oral cavity clean and their appliances well-maintained to avoid oral problems.
Calcium and Vitamin D Supplementation as Non-Surgical Treatment for Periodontal Disease with a Focus on Female Patients: Literature Review
Authors: Sllamniku Dalipi Zana , Dragidella Fatmir
Published: July 2022

Periodontal disease is a complex disease that involves an imbalance between the oral microbiota and an individual’s inflammatory response. Moreover, the inflammatory response contributes to further imbalance; if left untreated, periodontal disease may result in tooth loss. Vitamin D is intricately involved in the regulation of calcium–phosphate homeostasis and bone mineral metabolism; considering that periodontal surgery usually includes regenerative therapy, adequate vitamin D and calcium levels are essential. The benefits of vitamin D and calcium supplementation have been demonstrated in situations where deficiency is associated with adverse outcomes, such as periodontal disease and maternal health. However, knowledge and attitudes about supplementation, as well as the actual levels of supplementation, vary greatly in the general population; they also differ between men and women. The aim of this review is to discuss how vitamin D and calcium supplementation affect oral and periodontal health, especially in women. Additionally, this review provides suggestions for public health strategies regarding vitamin D and calcium supplementation, as well as the effects of both types of supplementation on maternal oral health.
Smoking as a Risk Factor for Dry Socket: A Systematic Review
Authors: Kuśnierek Weronika , Brzezińska Kaja , Nijakowski Kacper , Surdacka Anna
Published: July 2022

Dry socket is one of the postoperative complications of tooth extraction. It is the partial or total loss of the post-extraction blood clot, resulting in severe pain that usually starts one to five days postoperatively, with clinical evidence of exposed alveolar bone, necrotic debris, halitosis, and tenderness on examination. The purpose of our systematic review was to answer the question “Is there a relationship between smoking and dry socket?”. After meeting the inclusion and exclusion criteria, eleven studies were included in this systematic review (according to the PRISMA statement guidelines). Based on a meta-analysis, tobacco smokers had a more than three-fold increase in the odds of dry socket after tooth extraction. Overall, the combined incidence of dry socket in smokers was found to be about 13.2% and in non-smokers about 3.8%. Despite the heterogeneity of the included studies (different types of teeth extracted, different age groups), cigarette smoking was related to an increased risk of dry socket after tooth extraction.
Caries Experience and Erosive Tooth Wear in Finnish Men Conscripts 2021: A Cross-Sectional Study
Authors: Patinen Pertti , Tanner Tarja , Huttunen Mika , Muhonen Annakaisa , Räsänen Sari , Moilanen Pernelle , Päkkilä Jari , Anttonen Vuokko , Kämppi Antti
Published: July 2022

Background: In Finland, the development of oral health in young, 19- to 21-year-old males regarding restorative treatment need seems to have slowed down according to cross-sectional conscript studies between 1976 and 2011. At the individual level, the mean number of decayed teeth (DT > 0) has also steadily continued to decline. In Finland, military service is mandatory, and around 85% of males complete it. The aim of this cross-sectional study was to investigate the oral health status of young men at the beginning of the 2020s. Methods: The data were collected in July 2021 in the eight biggest Finnish Defence force garrisons by ten calibrated dentists serving in the ranks. The inclusion criteria for this study were a year of birth between 2000 and 2002 and male gender (n = 508). Third molars were included. Restorative treatment need was evaluated using ICDAS scoring. The study was designed according to the STROBE guidelines. Results: Mean DT value was 1.13 when third molars were included and 1.03 when they were excluded. Mean DMFT value was 3.23 and 2.98, respectively. The proportion of conscripts with DT > 0 was 36.4% and 34.8%, respectively. The prevalence of caries was concentrated among a small number of conscripts. Most (76.5%) had BEWE (basic erosive wear examination) of 0–2. Conscripts in the moderate and severe ETW (erosive tooth wear) groups (BEWE 3–13) comprised 23.5% of the cohort. None of the conscripts fell into the most severe group (BEWE 14–18). Conclusions: The oral health of conscripts has improved over the last ten years, and restorative treatment need has decreased significantly. Compared to previous studies, restorative treatment need was concentrated on an even smaller proportion of conscripts.
The Effect of Scanning Strategy on Intraoral Scanner’s Accuracy
Authors: Gavounelis Nikolaos A. , Gogola Chrysoula-Maria C. , Halazonetis Demetrios J.
Published: July 2022

The purpose of the present study was to examine the impact of scanning strategy on trueness and precision of the impression acquired from an intraoral scanner. Fifteen complete-arch, mandibular, post-orthodontic treatment casts were scanned with a laboratory scanner (Identica SE 3D, Medit) as the gold standard, and with an intraoral scanner (i500 Medit) following three different paths of the scanning head over the arch (scanning strategies A, B, and C). The hand scans were performed twice by one examiner and repeated by a second examiner, resulting in 180 triangular mesh surfaces (digital casts). The meshes were superimposed on the gold standards using the Viewbox 4 software. The closest distances between the meshes were computed and trueness and precision were evaluated using a General Linear Model. An interaction was found among the examiner and strategy. The accuracy of complete-arch impressions was affected by the scanning strategy; the manufacturer’s recommended strategy (A) was statistically significantly better (p < 0.05) than B and C, which were similar. An average accuracy below 50 μm, which is clinically acceptable in most orthodontic procedures, was achieved with all the examined scanning strategies.
In the Heat of the Night: Comparative Assessment of Drone Thermography at the Archaeological Sites of Acquarossa, Italy, and Siegerswoude, The Netherlands
Authors: Waagen Jitte , Sánchez Jesús García , van der Heiden Menno , Kuiters Aaricia , Lulof Patricia
Published: July 2022

Although drone thermography is increasingly applied as an archaeological remote sensing tool in the last few years, the technique and methods are still relatively under investigated. No doubt there are successes in positive identification of buried archaeology, and the prospection technique has clear complementary value. Nevertheless, there are also instances where thermograms did not reveal present shallow buried architectural features which had been clearly identified by, for example, ground-penetrating radar. The other way around, there are cases where the technique was able to pick up a signals of buried archaeology at a time of day that is supposed to be very unfavorable for thermographic recording. The main issue here is that the exact factors determining the potential for tracing thermal signatures of anthropomorphic interventions in the soil are many, and their effect, context, and interaction under investigated. This paper deals with a systematic application of drone thermography on two archaeological sites in different soils and climates, one in The Netherlands, and one in Italy, to investigate important variables that can make the prospection technique effective.
FedHGCDroid: An Adaptive Multi-Dimensional Federated Learning for Privacy-Preserving Android Malware Classification
Authors: Jiang Changnan , Yin Kanglong , Xia Chunhe , Huang Weidong
Published: July 2022

With the popularity of Android and its open source, the Android platform has become an attractive target for hackers, and the detection and classification of malware has become a research hotspot. Existing malware classification methods rely on complex manual operation or large-volume high-quality training data. However, malware data collected by security providers contains user privacy information, such as user identity and behavior habit information. The increasing concern for user privacy poses a challenge to the current malware classification scheme. Based on this problem, we propose a new android malware classification scheme based on Federated learning, named FedHGCDroid, which classifies malware on Android clients in a privacy-protected manner. Firstly, we use a convolutional neural network and graph neural network to design a novel multi-dimensional malware classification model HGCDroid, which can effectively extract malicious behavior features to classify the malware accurately. Secondly, we introduce an FL framework to enable distributed Android clients to collaboratively train a comprehensive Android malware classification model in a privacy-preserving way. Finally, to adapt to the non-IID distribution of malware on Android clients, we propose a contribution degree-based adaptive classifier training mechanism FedAdapt to improve the adaptability of the malware classifier based on Federated learning. Comprehensive experimental studies on the Androzoo dataset (under different non-IID data settings) show that the FedHGCDroid achieves more adaptability and higher accuracy than the other state-of-the-art methods.
Numerical Investigation of Exergy Loss of Ammonia Addition in Hydrocarbon Diffusion Flames
Authors: Sun Haifeng , Zhang Zhongnong , Sun Hanxiao , Yao Bin , Lou Chun
Published: July 2022

In this paper, a theoretical numerical analysis of the thermodynamics second law in ammonia/ethylene counter-flow diffusion flames is carried out. The combustion process, which includes heat and mass transfer, as well as a chemical reaction, is simulated based on a detailed chemical reaction model. Entropy generation and exergy loss due to various reasons in ammonia/ethylene and argon/ethylene flames are calculated. The effects of ammonia addition on the thermodynamics efficiency of combustion are investigated. Based on thermodynamics analysis, a parameter, the lowest emission of pollutant (LEP), is proposed to establish a relationship between the available work and pollutant emissions produced during the combustion process. Chemical reaction paths are also analyzed by combining the chemical entropy generation, and some important chemical reactions and substances are identified. The numerical results reveal that ammonia addition has a significant enhancement on heat transfer and chemical reaction in the flames, and the total exergy loss rate increases slightly at first and then decreases with an increase in ammonia concentration. Considering the factors of thermodynamic efficiency, the emissions of CO2 and NOx reach a maximum when ammonia concentration is near 10% and 30%, respectively. In terms of the chemical reaction path analysis, ammonia pyrolysis and nitrogen production increase significantly, while ethylene pyrolysis and carbon monoxide production decrease when ammonia is added to hydrocarbon diffusion flames.
Numerical Study on Entropy Generation of the Multi-Stage Centrifugal Pump
Authors: Fan Baoxin , Liang Zhaoyu , Fan Ruonan , Chen Songying
Published: July 2022

The energy loss of the multi-stage centrifugal pump was investigated by numerical analysis using the entropy generation method with the RNG k-ε turbulence model. Entropy generation due to time-averaged motion and velocity fluctuation was mainly considered. It was found that the entropy generation of guide vanes and impellers account for 71.2% and 23.3% of the total entropy generation under the designed flow condition. The guide vanes are the main hydraulic loss domains and their entropy generation is about 9 W/K, followed by impellers. There are vortices at the tongue of the guide vane inlet as well as flow separations in the impellers, which lead to entropy generation. The fluid impacts the outer surface of the guide vanes, resulting in the increase in entropy generation. There are refluxes near the guide vane tongues which also increase the entropy generation of this part. The entropy generation distribution of the guide vanes and impellers was investigated, which found that the positive guide vane has more entropy generation compared with the reverse guide. The entropy generation of the blade suction surface is higher compared with the pressure surface. This study indicated that the entropy generation method has distinct advantages in the assessment of hydraulic loss.
Optimization of Pollutant Discharge Permits, Using the Trading Ratio System: A Case Study
Authors: Taheriyoun Masoud , Marzban Hossein , Geranmehr Mohammadali , Nazari-Sharabian Mohammad
Published: July 2022

Water quality management of rivers is one of the challenges in the analysis of water resource systems. The optimal operation of the pollutant carrying capacity of these systems provides significant economic value and could reduce treatment costs. In this study, the application of the trading ratio system is investigated to control the cost of pollutants in a river and make a fair deal. In this regard, transfer coefficients between pollution sources, along with the trade coefficients, are determined, considering the system limitations and each pollutant’s contaminant impact. To provide allowable limits of river water quality concentrations, the total cost of all sources and the system is minimized, using the linear programming method. Finally, the new trading discharge permits are calculated for each source. The proposed method is successfully applied to Dez River as a case study. Results show that using a trading ratio system could maintain water quality at a standard level containing economic benefits for the participants of this program.
The Role of Micro Waqf Bank in Women’s Micro-Business Empowerment through Islamic Social Finance: Mixed-Method Evidence from Mawaridussalam Indonesia
Authors: Soemitra Andri , Kusmilawaty  , Rahma Tri Inda Fadhila
Published: July 2022

This study examined the role of the Micro Waqf Bank in empowering women micro-entrepreneurs. This research used a mixed-method with an explanatory design. Quantitatively, this study examines the effect of the joint responsibility system, financing, and mentoring on the growth of the micro-enterprises business. The sample used was 200 women micro-entrepreneurs using a purposive sampling technique. Quantitative data analysis was performed using the Structural Equation Model based on Partial Least Squares (SEM PLS) technique. This research qualitatively analyzes how the Micro Waqf Bank has carried out its role in empowering women, including dealing with crises due to the COVID-19 pandemic. Thematic analysis was used as the qualitative data analysis technique. Informants in this study amounted to 6 informants from MWB Mawaridussalam consisting of Management, Mentors, and female micro-enterprises. The research results quantitatively indicate that there is a positive and significant impact on the joint responsibility system, financing, and mentoring on the development of micro-enterprise members. Mentoring is the most significant variable that impacts the growth of a micro-enterprise business. Qualitatively, the research results show the role of the Micro Waqf Bank in the economic empowerment of women micro-business entrepreneurs by specifically recommending reinforcement of the mentoring function.
The Impact of COVID-19 on Economic Growth of Countries: What Role Has Income Inequality in It?
Authors: Ghecham Mahieddine Adnan
Published: July 2022

This paper argues that income inequality explains the variation in the economic performance of different countries over the first year of the COVID-19 pandemic. Unlike the conclusions reported by some studies, this study shows that health casualties caused by COVID-19 has had a higher adverse economic impact on countries with lower income inequality. Notwithstanding, the decline in the economic growth as well as the number of casualties caused by COVID-19 are, overall, proportionate to the level of income inequality of the country. Furthermore, the results show that countries with more dependence on the service sector and countries that implemented more restrictive measures (lockdowns) experienced a higher decline in GDP growth over the first year of the pandemic period. The paper concludes with some important policy implications that support the role of strong institutions in making economies resilient over a period of pandemic.
COVID-19 and the Key Digital Transformation Lessons for Higher Education Institutions in South Africa
Authors: Mhlanga David , Denhere Varaidzo , Moloi Tankiso
Published: July 2022

COVID-19 has left an unmistakable impression on the world stage. It has altered the global socio-economic landscape, forcing individuals to adapt and embrace new ways of doing business, as well as new ways of life. One of the most significant effects of the pandemic was to hasten the adoption of digital technologies by many areas of the global economy. Campus closures were observed in the higher education sector, putting an end to long-standing face-to-face teaching and learning. This necessitated the most rapid paradigm shift ever seen in this industry to continue educating and learning. An abrupt change to online learning, which is primarily reliant on digital technologies, occurred. As a result, the purpose of this article is to investigate and identify ten critical digital transformation lessons from COVID-19 for South African higher education institutions. Secondary data gathered from the literature research were used to meet the study’s goal. The study concluded by laying out the most important digital transformation lessons for South Africa, including the notion that the country should strive to build digital capabilities because digital technology gaps remain wide, among other things.
Algorithm Verification of Single-Shot Relativistic Emittance Proposed Measuring Method
Authors: Feigin Leon , Weinberg Amir , Nause Ariel
Published: July 2022

A 6 MeV hybrid photo-cathode gun is driving a THz-FEL in Ariel University, as well as other applications. An electron bunch with small transverse emittance is extracted from a copper photo-cathode using a 1 ps UV laser pulse, and then accelerated to a kinetic energy of 6.5 MeV. The Hybrid term is due to the unique standing wave-traveling wave sections in a single RF cavity. Since low emittance is crucial for FEL operation, the characterization of the electron beam requires measuring the transverse emittance, which will be compared with the predicted design and the 3D simulation obtained values, in order to verify their correctness. In this paper, we confirm the use of the multi-slit technique to measure emittance in the Hybrid beam in a single shot and develop a simple and convenient algorithm to be used in the experimental measurements. The experimental analysis requires image processing of the measured data, combined with a custom LabVIEW and Matlab scripts to control the hardware, and analyze the obtained data. Prior to experimentally measuring emittance, we perform a simulated experiment, using a simulated beam from the General Particle Tracer (GPT) code to test these algorithms and scripts, and compare the emittance obtained using the algorithm with GPT’s estimated emittance. Once concluded, this method will allow for a simple, fast and accurate single shot emittance measurement for the Hybrid accelerator beam.
A Study on the Optimal Control of Voltage Utilization for Improving the Efficiency of PMSM
Authors: Park Ji-Hwan , Lim Hee-Sun , Lee Geun-Ho , Lee Heon-Hyeong
Published: July 2022

When performing weak flux control to drive a permanent-magnet synchronous motor at high speed, the efficiency is lowered because the copper loss increases as the negative D-axis current increases. In addition, if the overmodulation index is slightly lowered and driven without setting it to the maximum value, the phase current ripple reduction effect can be expected compared to the six-step control. Therefore, if the motor is operated at a current point that can minimize the sum of copper loss and iron loss, the motor can be driven with maximum efficiency. In addition, if the overmodulation index is slightly lower than that of the six-step control, the phase current ripple can be reduced. This paper proposes a method for finding an overmodulation index to maximize driving efficiency when driving a motor based on the magnetic flux–torque command. In addition, an algorithm for driving a motor with maximum efficiency by applying an optimal overmodulation index table is proposed. Based on the MATLAB Simulink simulation, the efficiency change characteristics according to the overmodulation index change are reviewed, and the efficiency improvement and current ripple reduction effects are verified through a dynamometer experiment.
Implementation of DDS Cloud Platform for Real-Time Data Acquisition of Sensors for a Legacy Machine
Authors: Ho Min-Huang , Lai Ming-Yi , Liu Yung-Tien
Published: July 2022

Industry 4.0 (I4.0) is a multidisciplinary engineering principle combing the IoT (Internet of things), big data, and cloud computing to cope with the dynamic changing industry. In this paper, the DDS (data distribution service) communication protocol was employed to implement a cloud platform for data acquisition from various sensors on a precision legacy machine tool including an accelerometer and sound, temperature, brightness, and humidity sensors. The sensor signals were acquired using Raspberry Pi as the edge device, then published to the cloud using the DDS application, and stored in the MySQL database. Using the Django web server, the acquired sensor signals could be shown in real time on the webpage via a combination of MQTT and Node-RED. In addition, the motion displacement of the machine tool detected by the encoder could be recorded through the edge device for further performance examination. With the proposed DDS cloud platform, it is demonstrated that a legacy machine can enable sensing and communication abilities such that the development of a smart machine is achievable for future I4.0 application.
Thermal Characteristic of Novel Insulation Materials Designed for Solar Simulator
Authors: Ding Wenjing , Zhou Ying , Gu Miao , Gong Jie , Xu Jinghao
Published: July 2022

The solar simulator is an important device for simulating solar irradiation in cold black and vacuum environments and has a wide range of application prospects. In this work, a method of thermal conductivity measurement by a double specimen protection thermal plate method under vacuum conditions was proposed, and the thermal conductivity of a new thermal insulation material under a cryogenic vacuum environment was studied. By designing a vacuum adjustment device and a multi-layer insulation structure with a low outgassing rate, it is possible to adjust the vacuum pressure from 10−4 Pa to atmospheric. A temperature control and thermal conductivity test can be realized from −160 °C to 280 °C by the joint temperature control of liquid nitrogen cooling and electric heating. Then, the measurement accuracy of the device was checked by the national standard sample, the thermal conductivity of the sample was measured under different vacuum and temperature conditions, the uncertainty analysis of the device was given, and, finally, the thermal conductivity of the new material was tested.
Detection of Random False Data Injection Cyberattacks in Smart Water Systems Using Optimized Deep Neural Networks
Authors: Moazeni Faegheh , Khazaei Javad
Published: July 2022

A cyberattack detection model based on supervised deep neural network is proposed to identify random false data injection (FDI) on the tank’s level measurements of a water distribution system. The architecture of the neural network, as well as various hyper-parameters, is modified and tuned to acquire the highest detection performance using the smallest size of training data set. The efficacy of the proposed detection model against various activation functions including sigmoid, rectified linear unit, and softmax is examined. Regularization and momentum techniques are applied to update the weights and prohibit overfitting. Moreover, statistical metrics are presented to evaluate the performance and effectiveness of the proposed model in the presence of a range of measurement noise levels. The proposed model is tested for three attack scenarios composed for the battle of the attack detection algorithms. Results confirm that the size of the data sets required to train the neural network (NN) to accomplish the highest levels of accuracy and precision is significantly decreased as the number of hidden layers is increased. The trained 4- and 5-layer deep neural networks are able to detect the readings’ FDIs with 100% precision and accuracy in the presence of 30% background noise in the sensory data.
Constructing High-Performance Carbon Nanofiber Anodes by the Hierarchical Porous Structure Regulation and Silicon/Nitrogen Co-Doping
Authors: Chen Yujia , Wang Jiaqi , Wang Xiaohu , Li Xuelei , Liu Jun , Liu Jingshun , Nan Ding , Dong Junhui
Published: July 2022

Due to the rapid development of bendable electronic products, it is urgent to prepare flexible anode materials with excellent properties, which play a key role in flexible lithium-ion batteries. Although carbon fibers are excellent candidates for preparing flexible anode materials, the low discharge specific capacity prevents their further application. In this paper, a hierarchical porous and silicon (Si)/nitrogen (N) co-doped carbon nanofiber anode was successfully prepared, in which Si doping can improve specific capacity, N doping can improve conductivity, and a fabricated hierarchical porous structure can increase the reactive sites, improve the ion transport rate, and enable the electrolyte to penetrate the inner part of carbon nanofibers to improve the electrolyte/electrode contacting area during the charging–discharging processes. The hierarchical porous and Si/N co-doped carbon nanofiber anode does not require a binder, and is flexible and foldable. Moreover, it exhibits an ultrahigh initial reversible capacity of 1737.2 mAh g−1, stable cycle ability and excellent rate of performance. This work provides a new avenue to develop flexible carbon nanofiber anode materials for lithium-ion batteries with high performance.
A New Reliability Allocation Method Based on PSA and AHP for Fusion Reactors
Authors: Sun Ming , Li Taosheng , Yu Jie , Ge Daochuan , Bai Ying , Tao Longlong
Published: July 2022

Reasonable and feasible reliability index allocation is significant for improving safety and reducing costs for fusion reactors. Although the reliability index is allocated when designing some key systems, reliability allocation is not implemented from the overall layer to the system and component layers for fusion reactors. In this contribution, fusion reactors are divided into different layers by applying the Analytic Hierarchy Process (AHP); these layers include the overall layer, system layer and component layer, failure mode layer, etc. Combining the Probabilistic Safety Assessment (PSA) model for fusion reactors and AHP, the reliability index is allocated from the overall layer to the system and component layer. Firstly, a new reliability index allocation method based on PSA and AHP for fusion reactors is proposed. Secondly, the PSA model for an in-vessel LOCA accident of fusion reactors is selected as a case study to demonstrate the applications of the proposed method. Lastly, the relationship between PSA, items safety classification and reliability allocation are discussed. The allocation results indicate that the proposed method provides a more systematic reliability allocation scheme and contributes to improving the safety and economy of fusion reactors.
Analysis of Undergraduates’ Environmentally Friendly Behavior: Case Study of Tzu Chi University Environmental Education Program
Authors: Tsai Angela Yi Jing , Tan Alex Yong Kwang
Published: July 2022

The Tzu Chi University Environmental Education Program, based on a theory of change, consisted of four weeks of lessons involving environmental and sustainability topics, followed by hands-on sorting of recyclables and four weeks of weekly documenting of environmentally friendly behavior. The Program was analyzed using written thoughts from the Experimental Group, as well as 78 and 116 valid survey responses of the Control and Experimental Groups, respectively. The survey consisted of questions regarding demographics and five constructs: environmental awareness, attitudes, norms, efficacy and behavior. No significant average differences were found between the pre-tests of the Control and Experimental Groups, or between the pre- and post-test of the Control Group. The post-test of the Experimental Group displayed a significantly higher average value when compared to both the pre-test of the Experimental Group and the post-test of the Control Group, as the means of the self-reported environmental awareness, attitudes, norms, efficacy and behavior significantly improved statistically after participating in the Program. Analysis revealed that lessons from the Program increased undergraduates’ environmental awareness and attitudes; “hands-on recyclables sorting” and “weekly documentation of environmentally friendly behavior” strengthened undergraduates’ environmental norms and efficacy, while their combination resulted in a significant improvement toward environmentally friendly behavior.
Building Analytics Tool Deployment at Scale: Benefits, Costs, and Deployment Practices
Authors: Lin Guanjing , Kramer Hannah , Nibler Valerie , Crowe Eliot , Granderson Jessica
Published: July 2022

Buildings are becoming more data-rich. Building analytics tools, including energy information systems (EIS) and fault detection and diagnostic (FDD) tools, have emerged to enable building operators to translate large amounts of time-series data into actionable findings to achieve energy and non-energy benefits. To expedite data analytics adoption and facilitate technology innovation, building owners, technology developers, and researchers need reliable cost–benefit data and evidence-based guidance on deployment practices. This paper fulfills these needs with the energy use and survey data from a wide-ranging research and industry partnership program that covers thousands of buildings installed with analytics tools. The paper indicates that after two years of implementation, organizations using FDD tools and EIS tools achieved 9% and 3% median annual energy savings, respectively. The median base cost and annual recurring cost for FDD are USD 0.65 per square meter (m2) (USD 0.06 per square foot [ft2]) and USD 0.22 per m2 (USD 0.02 per ft2), and are USD 0.11 per m2 (USD 0.01 per ft2) and USD 0.11 per m2 (USD 0.01 per ft2) for EIS. The common metrics and analyses that are used in the tools to support the discovery of energy efficiency measures are summarized in detail. Two best practice examples identified to maximize the benefits of tool implementation are also presented. Opportunities to advance the state of technology include simplified data integration and management, and more efficient processes for acting on analytics outputs. Compared with previous efforts in the literature, the findings presented in this paper demonstrate the effectiveness of building analytics tools with the largest known dataset.
The Influence of Diethylaniline and Toluene on the Streamer Propagation in Cyclohexane between a Point-Plane Gap under Positive Impulse Voltage Stress
Authors: Wolmarans Carl P. , Nyamupangedengu Cuthbert , Schumann Carina , Coville Neil J. , Saba Marcelo M. F.
Published: July 2022

Liquid insulation is used in high voltage equipment such as power transformers as both dielectric medium and coolant. Breakdown in liquid insulation tends to be governed either by streamer initiation under more uniform fields, or by streamer propagation under more non-uniform fields. A model streamer propagation study, which screens the effectiveness of additives based on cyclohexane and mixtures with diethylaniline (DEA) and toluene, is presented in this paper. The effect of additives, at different concentrations, on streamer propagation velocity in cyclohexane under an applied lightning impulse voltage of positive polarity is studied. Cyclohexane (ionisation potential 9.88 eV) was chosen because, being a hydrocarbon, it shares similarities with the constituents of common insulating liquids. Previous studies have also shown how, in general, the addition of additives of lower ionization potential than the bulk liquid can slow down streamer propagation in insulating liquids. A point-plane electrode configuration of 70 mm gap with a 5 μm tip radius is used and subjected to an applied positive polarity impulse of 1.2/50 μs. A high velocity imaging system is also used to capture streamer images to validate a Time-To-Breakdown (TTB) measurement approach used in inferring approximate streamer velocity. The DEA (ionisation potential 6.98 eV) was found to be an effective additive to slow down positive polarity streamers in cyclohexane in the applied voltage range (≈220–280 kV peak) in concentrations above approximately 0.33% (by volume). Toluene (ionisation potential 8.82 eV) was found not to significantly slow down streamers in cyclohexane, even at 10% concentration, for the same voltage range. This is postulated to be due to the fact that toluene does not have a low enough ionisation potential (with respect to that of the cyclohexane) to change the streamer branching characteristics sufficiently during propagation.
Noninvasive Methods of Active Thermographic Investigation: Short Overview of Theoretical Foundations with an Example of Application
Authors: Gryś Sławomir , Minkina Waldemar
Published: July 2022

The field of non-destructive testing using thermography (NDT—Non-Destructive Testing and NDE—Non Destructive Evaluation) was established in the 1960s as a competitive and complementary method to ultrasonic or X-ray testing. Non-destructive quality control of objects is essential in modern industry, especially in mass production. It is an integral part of the quality control process. The reason for the introduction of non-destructive testing into diagnostic techniques were disasters and failures of various equipment and structures. Over the years, a division has been drawn between passive and active thermography. The aim of this publication is to present the theoretical basis of non-destructive testing with the use of active infrared thermography methods. It describes selected models of transient heat flow (thermal wave) in objects of various shapes and physical properties. They are the basis for understanding the changes in the surface temperature of the studied objects in time, which are the response to thermal excitation of different nature. An example of their effective application in engineering practice is the author’s software, in which the recorded time response is matched to the analytical solution, and on this basis detected anomalies are parameterized, detected by the fusion of various techniques of thermal image processing and analysis methods.
Numerical Study of the Effect of the Rolling Motion on the Subcooled Flow Boiling in the Subchannel
Authors: Li Yaru , Chi Xiangyu , Nan Zezhao , Yin Xuan , Ren Xiaohan , Wang Naihua
Published: July 2022

The marine environment may change the force on the fluid and inevitably influence bubble behavior and the two-phase flow in the reactor core, which are vital to the safety margin of a nuclear reactor. To explore the effect of the marine motion on the flow and heat transfer features of subcooled flow boiling in the reactor core, the volume of fluid (VOF) method is employed to reveal the interaction between the interface structure and two-phase flow in the subchannel under rolling motion. The variations of several physical parameters are obtained, including the transverse flow, the vapor volume fraction, the vapor adhesion ratio, and the phase distribution of boiling two-phase flow with time. Sensitivity analyses of the amplitude and the period of the rolling motion were performed to demonstrate the mechanisms of the influence of the rolling motion. We found that the transverse flow in the subchannel was mainly affected by the Euler force under the rolling motion. In contrast to the two-phase flow in the static state, the vapor volume fraction and vapor adhesion ratio show different characteristics under rolling motion. Additionally, the onset of significant void (OSV) point changes periodically under rolling motion.
Characterization of Dioxins and Heavy Metals in Chelated Fly Ash
Authors: Pan Shuping , Yao Qi , Cai Wenxiang , Peng Yaqi , Luo Yuhao , Wang Zhizhen , Jiang Caiping , Li Xiaodong , Lu Shengyong
Published: July 2022

Municipal solid waste incineration (MSWI) fly ash contains highly toxic heavy metals and polychlorinated dibenzo dioxins/furans (PCDD/Fs), which are a type of hazardous waste. The pollution characteristics of fly ash have changed with the development of stoker grate incinerators and the fly ash treatment technology; however, no research has been focused on this in recent years. In this study, 12 fly ash samples were collected from 9 grate power plants in southeastern China, and their PCDD/Fs and heavy metal concentrations were determined and compared to previous fly ash data. The PCDD/Fs concentration in fly ash was in the range of 0.002–0.051 ngI-TEQ/g, with an average of 0.027 ngI-TEQ/g. Furthermore, 1,2,3,4,6,7,8-HpCDD and OCDD made the most significant contributions to PCDDs. The distribution of 10 dioxins exhibited bimodal, unimodal, and normal characteristics. Linear fitting demonstrated a strong correlation between toxicity and 1,2,3,7,8-PentaCDD, 1,2,3,7,8-PentaCDF, and 2,3,4,7,8-PentaCDF. Concerning heavy metals, Pb poses a significant environmental risk. This is the first time that fly ash treated with a chelating agent has been thoroughly analyzed, which is vital for understanding the pollution level and treatment of fly ash derived from current power plants.
Review of Gas Engine Heat Pumps
Authors: Pawela Bartosz , Jaszczur Marek
Published: July 2022

In this paper the most promising developments of technology for gas engine-driven heat pumps for the last 15 years are presented. The purpose is to present the latest research studies and changes in this type of device, as well as to help readers to search for publications containing relevant aspects of gas engine heat pumps. Gas engine-driven heat pumps are devices for parallel heating and cooling production based on compressor heat pump technology. However, unlike heat pumps with compressors powered by electric motors, gas engine-driven heat pumps are driven by gas internal combustion engines. The reviewed solutions are an interesting alternative to traditional heating systems, characterized by the higher than 1.0 Performance Energy Ratio which expresses the degree of conversion of the energy contained in the fuel supplied to the device into energy transported to the utility needs. Presented in this review, papers show different solutions for conversion of the energy contained in the fuel into mechanical and thermal energy, and mechanical energy through the shaft system is used to drive the compressor of the heat pump. The presented study shows that, due to the complexity of the system and the wide range of applications, the technology has been subjected to detailed analyses and optimizations during the last 30 years in order to increase the efficiency of devices.
Optimization Design of Packaging Insulation for Half-Bridge SiC MOSFET Power Module Based on Multi-Physics Simulation
Authors: Li Wenyi , Wang Yalin , Ding Yi , Yin Yi
Published: July 2022

With the development of power modules for high voltage, high temperature, and high power density, their size is becoming smaller, and the packaging insulation experiences higher electrical, thermal, and mechanical stress. Packaging insulation needs to meet the requirement that internal electric field, temperature, and mechanical stress should be as low as possible. Focusing on the coupling principles and optimization design among electrical, thermal, and mechanical stresses in the power module packaging insulation, a multi-objective optimization design method based on Spice circuit, finite element field numerical calculation, and multi-objective gray wolf optimizer (MOGWO) is proposed. The packaging insulation optimal design of a 1.2 kV SiC MOSFET half-bridge power module is presented. First, the high field conductivity characteristics of the substrate ceramic and encapsulation silicone of the packaging insulation material were tested at different temperatures and external field strengths, which provided the key insulation parameters for the calculation of electric field distribution. Secondly, according to the mutual coupling principles among electric–thermal–mechanical stress, the influence of packaging structure parameters on the electric field, temperature, and mechanical stress distribution of packaging insulation was studied by finite element calculation and combined with Spice circuit analysis. Finally, the MOGWO algorithm was used to optimize the electric field, temperature, and mechanical stress in the packaging insulation. The optimal structural parameters of the power module were used to fabricate the corresponding SiC MOSFET module. The fabricated module is compared with a commercial module by the double-pulse experiment and partial discharge experiment to verify the feasibility of the proposed design method.
An DPWM for Active DC-Link Type Quasi-Z-Source Inverter to Reduce Component Voltage Rating
Authors: Do Duc-Tri , Tran Vinh-Thanh , Nguyen Khai
Published: July 2022

The conventional DC-link type quasi-Z-source inverter has been known as a buck–boost inverter with a low component voltage rating. This paper proposes an active DC-link type quasi-Z-source inverter by adding one active switch and one diode to the impedance-source network to enhance the voltage gain of the inverter. As a result, the component voltage rating of the inverter is significantly reduced, which is demonstrated through some comparisons between the proposed topology and others. A discontinuous pulse width modulation (DPWM) scheme is proposed to control the inverter, which reduces the number of commutations compared to the traditional strategy. Under this approach, the insertion of a shoot-through state does not cause any extra commutations compared to the conventional voltage-source inverter. Details about control implementation, steady-state analysis, and design guidelines are also presented in this paper. Simulation and a laboratory prototype have been built to test the proposed inverter. Both buck and boost operations of the proposed inverter are implemented to validate the performance of the inverter.