bluuebunny/crossref_metadata_2025 huggingface dataset:
A Spray-On Microemulsion with Mold-Proof Effect on Paper
Authors: Liu Naiming , Chu Depeng , Chen Xianlin , Fu Peng , Xing Huiping , Chao Xiaolian , Luo Yujia , Mai Bingjie , Li Yuhu
Published: April 2023

Archives, ancient books, and documents kept in museums and libraries are the carriers of historic and cultural information left by our ancestors. However, these paper cultural relics can show notorious signs of degradation, e.g., fungal development. Due to the organic components of paper objects, they suffer from fungal biodeterioration. The excreted substances of fungi and the fungi’s structures themselves are often colored and interfere with the readability of the artifacts, diminishing their artistic and monetary values. In this study, we collected and separated the moldy archives collected in the Archives of Shaanxi Province (China) and obtained the identification results of eight kinds of molds. Clotrimazole (CTZ) and quaternary ammonium salt chitosan (HACC) were combined to prepare a microemulsion. Synergies of CTZ and HACC could enhance the antifungal effect and reduce the required concentration of a single drug. The composite emulsion could effectively improve the retention of drugs on the surface of paper cultural relics, improve the solubility of hydrophobic drugs, and provide a data basis for the anti-mold preservation of paper cultural relics.
Evaluation of Untreated and Surface-Treated Wooden Facades of Buildings in Sweden
Authors: Bahrami Alireza , Hornborg Angelika , Persson Sofia , Norén Johan , Asplin Björn Bengtsson
Published: April 2023

In this research, untreated and surface-treated wooden facades of buildings are investigated and compared with regard to durability, environmental impact, and cost using the document and literature studies supplemented with quantitative data. The investigation is based on the influence on the wood by external factors, either in its natural form or with a protective layer of a surface treatment. It is resulted from the study that from a durability viewpoint, it is not always advantageous to paint a wooden facade. Yakisugi, a thermal modification for wooden facades that involves burning the wood to create a protective surface layer, has shown better properties, which, in combination with a lower need for maintenance, can be considered the leading treatment for facades. From an environmental perspective, Yakisugi, like untreated wood, has demonstrated advantages compared with conventional paints. Paints often come with maintenance requirements that should be carried out correctly to avoid extensive costs. Cost is an important factor that can be decisive when users choose a surface treatment. What determines the cost is the relationship between durability and maintenance intervals. The need for the maintenance of paints leads to large financial costs during the working life of a wooden facade, which differs from Yakisugi or an untreated wooden facade that can be considered maintenance-free. In order to meet the growing environmental demands from a national level to a global scale, unconventional surface treatments for wooden facades should be promoted in the future.
Exploring Relaxation Phenomenon in Cu-Substituted Ba2NiWO6 Double Perovskites
Authors: Ramay Shahid M. , Aldosary Mohammed H. , Mustafa Ghulam M. , Saba Sadaf , Atiq Shahid , Aftab Sikandar , Ebdah M. A.
Published: April 2023

Double perovskites are an emerging class of functional materials with a great deal of durability perspective owing to their inherent flexibility in cation coordination selection. Here, we synthesized pristine and Cu2+-doped Ba2NiWO6 utilizing the solid-state reaction route to investigate their structural, morphological, and dielectric behavior. Structural examination revealed the development of a cubic crystal structure for both compositions, and Cu2+ integration in Ba2NiWO6 decreases the crystallite size. The spherical-shaped grains shrink in size and start agglomeration with Cu2+ incorporation. The incorporation of Cu2+ reduces the grain size, leads to accumulation of space charges at the grain boundaries, and thus, facilitates growth in the space charge polarization. This increases the dielectric constant of the material, thus making these compositions viable for advanced miniaturized electronic devices.
Advancing PLA 3D Printing with Laser Polishing: Improving Mechanical Strength, Sustainability, and Surface Quality
Authors: Mushtaq Ray Tahir , Iqbal Asif , Wang Yanen , Khan Aqib Mashood , Petra Mohammad Iskandar
Published: April 2023

Three-dimensional (3D) printing of polylactic acid using the fused filament fabrication approach is a widely used additive manufacturing method in various fields, despite the historical issue of substantial surface roughness in fused filament fabrication products. Several strategies have been utilized to minimize the surface roughness of 3D-printed items. However, laser polishing is a novel technique for reducing surface roughness and improving other material qualities. In this study, polylactic acid was examined using the laser polishing method for surface roughness and mechanical properties, such as tensile and flexural strength and laser scan time. Several trials were conducted to determine how changing the laser’s characteristics may affect the materials’ surface quality and mechanical qualities. Before the final test, preliminary tests were performed to determine the lowest potential heat-affected zone. Laser polishing reduced surface roughness by more than 88.8% (from 7.8 µm to 0.87 µm). The tensile strength of the specimen increased by 14.03%, from 39.2 MPa to 44.7 MPa. Polylactic acid had a constant flexural strength of 70.1 MPa before and after polishing, and the laser scan time for samples was 19.4 s. Polished morphologies were studied to learn more about the microstructure. These findings show that laser polishing can improve and modify the surface properties of a fused filament fabrication product, which can benefit the industry and researchers.
The Impact of Hysteresis Effect on Device Characteristic and Reliability for Various Fin-Widths Tri-Gate Hf0.5Zr0.5O2 Ferroelectric FinFET
Authors: Zhang Wen-Qi , Wu Po-Tang , Lin Yu-Heng , Yang Yi-Lin
Published: April 2023

In this study, we developed a facilitated ferroelectric high-k/metal-gate n-type FinFET based on Hf0.5Zr0.5O2. We investigated the impact of the hysteresis effect on device characteristics of various fin-widths and the degradation induced by stress on the ferroelectric FinFET (Fe-FinFET). We clarified the electrical characteristics of the device and conducted related reliability inspections. For the Fe-FinFET, the hysteresis behavior of the Hf0.5Zr0.5O2-based gate stack in the Si-fin body is apparent, especially at narrower fin-widths, which affects device performance and reliability under voltage stress. The gate ferroelectric film is worsened after voltage stress with higher impact ionization, resulting in hysteresis degradation and serious induced device performance degradation. It is suggested that the hysteresis degradation is caused by both a shift in polarization of the gate ferroelectric film and generation of interface traps after high-energy carrier stress, which was confirmed by crystal structure inspection.
Application of Co3O4 in Photoelectrocatalytic Treatment of Wastewater Polluted with Organic Compounds: A Review
Authors: Zhao Fanyue , Ma Hongchao
Published: April 2023

The negative effects of refractory organic substances in water on the environment and life have aroused worldwide attention. The efficiency of using photoelectrocatalysis (PEC) to degrade refractory organic pollutants depends to a large extent on the properties of the photoanode semiconductor. Therefore, the selection of a satisfactory photoanode semiconductor material to promote the production of intermediate reactive species (hydroxyl radicals and superoxide radicals) has become a key issue in improving the efficiency of PEC. Among the available catalysts, transition metal oxides have received a lot of attention in recent years due to their low price and significant advantages. Due to its outstanding photoelectrocatalytic properties, Co3O4 has emerged as a candidate to serve as a photoelectrocatalyst specifically for the oxidation of water with oxygen in these materials. This paper summarizes in detail the recent advances in Co3O4 materials for PEC, both pure Co3O4 and Co3O4-based composites. In addition, this review discusses the impact of strategies on the performance of photoelectrocatalysts, such as synthesis methods, crystal surface structures, and composites. Finally, this review concludes with a presentation of the challenges and workable solutions for Co3O4-based materials in PEC, along with a discussion of their potential for future research.
Small but Mighty: The Round Goby (Neogobius melanostomus) as a Model Species of Biological Invasions
Authors: Cerwenka Alexander F. , Brandner Joerg , Dashinov Dimitriy , Geist Juergen
Published: April 2023

Invasive “game-changer” species cause severe ecological impacts such as “phase shifts” in recipient ecosystems all over the world. Since the early 1990s, the ongoing global spread of the small but highly invasive Ponto-Caspian round goby Neogobius melanostomus into diverse freshwater and marine ecosystems has been observed. We postulate that this species is an ideal model to better understand and mitigate aquatic invasions. Its wide invaded range, as well as its diverse impacts on native species, have triggered a large body of research worldwide concerning its spread, ecology, and traits facilitating invasion. Several hypotheses related to invasiveness have been tested for the round goby, which are also applicable to other invasive species and for understanding general principles in invasion biology. However, a common theory explaining invasion success, especially in round goby, is still lacking. Many case studies do not consider time since invasion and use different sampling protocols and methodologies, hampering the comparability of results and conclusions. We thus propose strengthening the network of goby researchers and establishing long-term databases based on continuous and harmonized monitoring covering all stages of the invasion process as crucial requirements to better understand and manage aquatic invasions. In many cases, such monitoring can easily be integrated into existing survey schemes.
Analysis of Changes in Habitat Suitability of the Javan Leopard (Panthera pardus melas, Cuvier 1809) on Java Island, 2000–2020
Authors: As’ary Muhammad , Setiawan Yudi , Rinaldi Dones
Published: April 2023

The Javan leopard is an apex predator whose distribution is limited to the island of Java and Nusakambangan Island, and it is classified as an endangered species. The forest habitat of the Javan leopard is subject to annual damage, which causes a decrease in its quality and suitability as a habitat for this species. This study aimed to determine the changes in the suitability of the Javan leopard habitat from 2000 to 2020 and the variables affecting it. A habitat suitability analysis was performed using the MaxEnt application. The data included coordinate points and environment variables. The variables included the distance from rivers, undisturbed tropical forests, degraded forests, permanent water, shrubs, farms, plantations, and settlements. The model produced an AUC value of 0.812, indicating the model was good. In the 2000 model year, the highly suitable habitat area of the Javan leopard was 2481.38 km2, the suitable habitat area was 2630.763 km2, and the unsuitable area was 7790.155 km2. In the 2020 model, the area of highly suitable habitat was 1429.647 km2, the area of suitable habitat was 2379.344 km2, and the area that was not suitable was 9093.081 km2. Primary forest was the variable that contributed most to the model.
Genetic Variability and Connectivity in the Western Mediterranean Populations of the Bathyal Crab Geryon longipes
Authors: Colmenero Ariadna , Serra Bruna , Lagares Clàudia , Rojo-Francàs Eva , Pérez-Gil José L. , Mestres Francesc , Abelló Pere
Published: April 2023

Geryon longipes is a crab species that inhabits the muddy bottoms of the middle and lower slopes, as well as bathyal bottoms ranging from 400 to 2000 m in depth. To assess its molecular diversity, a fragment of 572 bp of the COI (Cytochrome Oxidase subunit I) mitochondrial gene was sequenced in eight Western Mediterranean locations. Within the studied area, two oceanographic fronts are present (Almeria-Oran Front and Ibiza Channel). From the 124 sequences obtained, only 7 distinct haplotypes were identified. The population distribution indicated three well-differentiated regions: the Alboran Sea, the Gulf of Vera and the Levantine/Catalan coasts. The molecular diversity was compared with that obtained in the same year for the same gene in Liocarcinus depurator, a crab species that is captured on the continental shelf and upper slope (40 to 500 m). The estimates of molecular diversity parameters for the COI gene fragment were rather similar between both species, but the number of haplotypes was higher for L. depurator. Finally, the obtained COI sequences of G. longipes were compared to those from other populations of the species distribution range, recovered from the DNA repository. Only one additional, different haplotype was reported (Sicily), whereas all the rest were common with those described in our study. Therefore, the COI gene fragment would indicate that all the sequences analysed in the Mediterranean and NE Atlantic belong to the same species, G. longipes.
From p-Values to Posterior Probabilities of Null Hypotheses
Authors: Vélez Ramos Daiver , Pericchi Guerra Luis R. , Pérez Hernández María Eglée
Published: April 2023

Minimum Bayes factors are commonly used to transform two-sided p-values to lower bounds on the posterior probability of the null hypothesis, in particular the bound −e·p·log(p). This bound is easy to compute and explain; however, it does not behave as a Bayes factor. For example, it does not change with the sample size. This is a very serious defect, particularly for moderate to large sample sizes, which is precisely the situation in which p-values are the most problematic. In this article, we propose adjusting this minimum Bayes factor with the information to approximate an exact Bayes factor, not only when p is a p-value but also when p is a pseudo-p-value. Additionally, we develop a version of the adjustment for linear models using the recent refinement of the Prior-Based BIC.
Integrated Multiresonator Quantum Memory
Authors: Perminov Nikolay Sergeevich , Moiseev Sergey Andreevich
Published: April 2023

We develop an integrated efficient multiresonator quantum memory scheme based on a system of three interacting resonators coupled through a common resonator to an external waveguide via switchable coupler. It is shown that high-precision parameter matching based on step-by-step optimization makes it possible to efficiently store the signal field and enables on-demand retrieval of the signal at specified time moments. Possible experimental implementations and practical applications of the proposed quantum memory scheme are discussed.
Source Acquisition Device Identification from Recorded Audio Based on Spatiotemporal Representation Learning with Multi-Attention Mechanisms
Authors: Zeng Chunyan , Feng Shixiong , Zhu Dongliang , Wang Zhifeng
Published: April 2023

Source acquisition device identification from recorded audio aims to identify the source recording device by analyzing the intrinsic characteristics of audio, which is a challenging problem in audio forensics. In this paper, we propose a spatiotemporal representation learning framework with multi-attention mechanisms to tackle this problem. In the deep feature extraction stage of recording devices, a two-branch network based on residual dense temporal convolution networks (RD-TCNs) and convolutional neural networks (CNNs) is constructed. The spatial probability distribution features of audio signals are employed as inputs to the branch of the CNN for spatial representation learning, and the temporal spectral features of audio signals are fed into the branch of the RD-TCN network for temporal representation learning. This achieves simultaneous learning of long-term and short-term features to obtain an accurate representation of device-related information. In the spatiotemporal feature fusion stage, three attention mechanisms—temporal, spatial, and branch attention mechanisms—are designed to capture spatiotemporal weights and achieve effective deep feature fusion. The proposed framework achieves state-of-the-art performance on the benchmark CCNU_Mobile dataset, reaching an accuracy of 97.6% for the identification of 45 recording devices, with a significant reduction in training time compared to other models.
CGA-MGAN: Metric GAN Based on Convolution-Augmented Gated Attention for Speech Enhancement
Authors: Chen Haozhe , Zhang Xiaojuan
Published: April 2023

In recent years, neural networks based on attention mechanisms have seen increasingly use in speech recognition, separation, and enhancement, as well as other fields. In particular, the convolution-augmented transformer has performed well, as it can combine the advantages of convolution and self-attention. Recently, the gated attention unit (GAU) was proposed. Compared with traditional multi-head self-attention, approaches with GAU are effective and computationally efficient. In this CGA-MGAN: MetricGAN based on Convolution-augmented Gated Attention for Speech Enhancement, we propose a network for speech enhancement called CGA-MGAN, a kind of MetricGAN based on convolution-augmented gated attention. CGA-MGAN captures local and global correlations in speech signals at the same time by fusing convolution and gated attention units. Experiments on Voice Bank + DEMAND show that our proposed CGA-MGAN model achieves excellent performance (3.47 PESQ, 0.96 STOI, and 11.09 dB SSNR) with a relatively small model size (1.14 M).
Relating a System’s Hamiltonian to Its Entropy Production Using a Complex Time Approach
Authors: Parker Michael C. , Jeynes Chris
Published: April 2023

We exploit the properties of complex time to obtain an analytical relationship based on considerations of causality between the two Noether-conserved quantities of a system: its Hamiltonian and its entropy production. In natural units, when complexified, the one is simply the Wick-rotated complex conjugate of the other. A Hilbert transform relation is constructed in the formalism of quantitative geometrical thermodynamics, which enables system irreversibility to be handled analytically within a framework that unifies both the microscopic and macroscopic scales, and which also unifies the treatment of both reversibility and irreversibility as complementary parts of a single physical description. In particular, the thermodynamics of two unitary entities are considered: the alpha particle, which is absolutely stable (that is, trivially reversible with zero entropy production), and a black hole whose unconditional irreversibility is characterized by a non-zero entropy production, for which we show an alternate derivation, confirming our previous one. The thermodynamics of a canonical decaying harmonic oscillator are also considered. In this treatment, the complexification of time also enables a meaningful physical interpretation of both “imaginary time” and “imaginary energy”.
E-Government as a Key to the Economic Prosperity and Sustainable Development in the Post-COVID Era
Authors: Goloshchapova Tatiana , Yamashev Vladimir , Skornichenko Natalia , Strielkowski Wadim
Published: April 2023

Our paper focuses on the role of e-government in relation to economic development within the post-COVID era. Nowadays, e-government represents the service which utilizes digital technology to create electronic pathways to improve the efficiency of public services, increase economic prosperity, and improve the standard of living. In this paper, we argue that e-government presents the only proper and viable model for public administration in the 21st century by embedding internet-based technologies to ensure smooth interactions between the government and its citizens, solving the most socially important problems, enabling internal communication between public servants, and delivering public services to the entire population regardless of age or gender. In addition, we show that stakeholders and policymakers should foster the development of an adequate and non-discriminatory environment for e-government through regulatory frameworks, policy guidelines, and government guarantees. Our study is based on the results of our own survey that was administered using a snowball and quasi-random sample of 400 respondents (aged 19–26 years; 56.2% females and 43.8% males) from the Czech Republic (N = 136) and the Russian Federation (N = 264), of whom 58% were women and 42% were men (M ± SD = 45.53 ± 11.46, median age 44). Our results show that the e-government enhancement concept has been perceived as an effective tool for fostering economic prosperity, tackling corruption, and helping to avoid uncertainty. Based on the theories of customer-focus and relationship marketing, this study suggests that the most significant factor influencing the success of e-government projects is citizen orientation, followed by channel and channel orientation, and technology orientation. We show that the governments of developing countries should prioritize e-government applications in their requests for international assistance and cooperation, as well as international financial support. Moreover, we argue that digital transformation should become the key element of the changing business and market needs in the post-COVID era.
Health Sciences before, during and after the COVID-19 Pandemic
Authors: Găman Mihnea-Alexandru
Published: April 2023

The COVID-19 pandemic has heavily influenced the teaching and practical training required for students enrolled in health sciences courses globally both at undergraduate, graduate and postgraduate levels [...]
A Current Spectrum-Based Algorithm for Fault Detection of Electrical Machines Using Low-Power Data Acquisition Devices
Authors: Asad Bilal , Raja Hadi Ashraf , Vaimann Toomas , Kallaste Ants , Pomarnacki Raimondas , Hyunh Van Khang
Published: April 2023

An algorithm to improve the resolution of the frequency spectrum by detecting the number of complete cycles, removing any fractional components of the signal, signal discontinuities, and interpolating the signal for fault diagnostics of electrical machines using low-power data acquisition cards is proposed in this paper. Smart sensor-based low-power data acquisition and processing devices such as Arduino cards are becoming common due to the growing trend of the Internet of Things (IoT), cloud computation, and other Industry 4.0 standards. For predictive maintenance, the fault representing frequencies at the incipient stage are very difficult to detect due to their small amplitude and the leakage of powerful frequency components into other parts of the spectrum. For this purpose, offline advanced signal processing techniques are used that cannot be performed in small signal processing devices due to the required computational time, complexity, and memory. Hence, in this paper, an algorithm is proposed that can improve the spectrum resolution without complex advanced signal processing techniques and is suitable for low-power signal processing devices. The results both from the simulation and practical environment are presented.
An Intelligent Intrusion Detection System for 5G-Enabled Internet of Vehicles
Authors: Sousa Breno , Magaia Naercio , Silva Sara
Published: April 2023

The deployment of 5G technology has drawn attention to different computer-based scenarios. It is useful in the context of Smart Cities, the Internet of Things (IoT), and Edge Computing, among other systems. With the high number of connected vehicles, providing network security solutions for the Internet of Vehicles (IoV) is not a trivial process due to its decentralized management structure and heterogeneous characteristics (e.g., connection time, and high-frequency changes in network topology due to high mobility, among others). Machine learning (ML) algorithms have the potential to extract patterns to cover security requirements better and to detect/classify malicious behavior in a network. Based on this, in this work we propose an Intrusion Detection System (IDS) for detecting Flooding attacks in vehicular scenarios. We also simulate 5G-enabled vehicular scenarios using the Network Simulator 3 (NS-3). We generate four datasets considering different numbers of nodes, attackers, and mobility patterns extracted from Simulation of Urban MObility (SUMO). Furthermore, our conducted tests show that the proposed IDS achieved F1 scores of 1.00 and 0.98 using decision trees and random forests, respectively. This means that it was able to properly classify the Flooding attack in the 5G vehicular environment considered.
Determination of Critical Point of Particle Migration Direction in a Confined Shear Flow of Giesekus Fluids
Authors: Li Zhenna , Liu Bingrui , Lin Jianzhong
Published: April 2023

Migration of a particle in a confined shear flow of Giesekus fluids is investigated numerically with the method of direct forcing/fictitious domain. We focus on the migration direction for the particle with initial lateral position y0 and determination of critical point yc of a particle moving towards the center line or wall. The effect of viscosity ratio μr, shear-thinning parameter α, Weissenberg number Wi, and blocking rate β on the value yc is analyzed. The results showed that when μr ≤ 0.5, the particle will migrate towards the wall regardless of the value of y0. When μr > 0.5, yc increases with increasing μr, and some particles will migrate towards the center line with the increase in μr. The particle is more likely to migrate towards the center line at small values of Wi and α but at large values of μr. The impact of Wi and β on the particle migration direction is more obvious. The particle will migrate towards the wall for β = 0.3 and is more likely to migrate towards the wall with increasing β. α and Wi have little influence on the pressure distribution in the case of the same β and μr. The particle near the wall will migrate faster because large positive pressure and negative pressure appear around the particle.
Operation Approval for Commercial Airborne Wind Energy Systems
Authors: Salma Volkan , Schmehl Roland
Published: April 2023

Integrating the operation of airborne wind energy systems safely into the airspace requires a systematic qualification process. It seems likely that the European Union Aviation Safety Agency will approve commercial systems as unmanned aircraft systems within the “specific” category, requiring risk-based operational authorization. In this paper, we interpret the risk assessment methodology for airborne wind energy systems, going through the ten required steps of the recommended procedure and discussing the particularities of tethered energy-harvesting systems. Although the described process applies to the entire field of airborne wind energy, we detail it for a commercial flexible-wing airborne wind energy system. We find that the air risk mitigations improve the consolidated specific assurance and integrity level by a factor of two. It is expected that the framework will increase the safety level of commercial airborne wind energy systems and ultimately lead to operation approval.
Learning from Other Community Renewable Energy Projects: Transnational Transfer of Multi-Functional Energy Gardens from the Netherlands to Germany
Authors: Di Nucci Maria Rosaria , Krug Michael , Schwarz Lucas , Gatta Vincenzo , Laes Erik
Published: April 2023

Citizen energy in general and renewable energy communities (RECs) in particular are becoming key vehicles for decentralisation, but also for the democratisation of the energy system. These initiatives are now more diverse than ever and are likely to continue to act as incubators for significant projects in the transition to a renewable energy system. Beside the legal, regulatory, and financial challenges, there are several socio-economic and regulatory barriers that hinder the implementation of community energy projects. For this reason, policy learning and the dissemination of good/best practices that are transferable also to other contexts are important. This is an aspect that has not yet attracted much investigation, and only a few studies have explored the importance of transfer activities for the implementation of REC initiatives and their motives. This article aimed to address this knowledge gap by focussing on the transfer processes of best practices initiated in a particular region and discusses how these can be adapted and transferred to other contexts. We analysed the transfer case of a community renewable energy initiative, the multifunctional energy gardens, from the Netherlands to the German federal State of Thuringia, and extracted lessons with an overall validity for the transferability of drivers and success factors. We show how examples from other contexts with similar enabling conditions can represent significant foundations on which to build an effective strategy and what framework conditions are necessary to enhance the uptake of pervasive community energy initiatives in regions with low community energy development.
Gas Hydrates Reserve Characterization Using Thermo-Hydro-Mechanical Numerical Simulation: A Case Study of Green Canyon 955, Gulf of Mexico
Authors: Dhakal Sulav , Gupta Ipsita
Published: April 2023

The Gulf of Mexico is a widely explored and producing region for offshore oil and gas resources, with significant submarine methane hydrates. Estimates of hydrate saturation and distribution rely on drilling expeditions and seismic surveys that tend to provide either large-scale estimates or highly localized well data. In this study, hydrate reserve characterization is done using numerical simulation at Green Canyon block 955 (GC955). In addition, coupled thermo-hydro-mechanical (THM) simulation results show that hydrate saturation and geobody distribution are determined by the thermodynamic conditions as well as reservoir structures, stratigraphic differences, and permeability differences. Hydrate formation due to upflow of free gas and dissociation due to gas production and oceanic temperature rise due to climate change are simulated. The abundance of free gas under the hydrate stability zone and favorable pressure and temperature meant little hydrate was depleted from the reservoir. Furthermore, the maximum displacement due to warming reached 0.5 m in 100 years and 4.2 m in 180 days based on a simulation of constant production of methane gas. The displacement direction and magnitude suggest that there is little possibility of slope failure. Therefore, the GC955 site studied in this paper can be considered a favorable site for potential hydrate exploitation.
Sustainable Retrofit of Existing Buildings: Impact Assessment of Residual Fluorocarbons through Uncertainty and Sensitivity Analyses
Authors: Maracchini Gianluca , Di Filippo Rocco , Albatici Rossano , Bursi Oreste S. , Di Maggio Rosa
Published: April 2023

Fluorocarbons are an important category of greenhouse gas emissions, and currently, their use is prohibited due to their significant contribution to the global ozone depletion potential (ODP). During this century, they will continue to emit greenhouse gases into the environment since they are present in the thermal insulation foam and HVAC systems in existing buildings; however, proper disposal of these banks of CFCs/HFCs from existing buildings can limit their effects on the environment. However, there are no studies that have investigated quantifying the achievable environmental savings in this case. In this study, a comparative life cycle assessment (LCA) is conducted to evaluate, for the first time in the literature, the environmental savings achievable through the removal and disposal of CFC/HFC banks from buildings including damage-related emissions. To cope with the scarcity of data, uncertainty and sensitivity analysis techniques are applied. The results show that, for the selected archetype building, the largest annual emissions of CFCs/HFCs come from the external thermal insulation of the envelope. The removal of this material can lead to an additional significant reduction in the GWP (up to 569 kgCO2eq/m2) and the ODP (up to 117 × 10−3 kgCFC-11eq/m2), i.e., higher than that achievable by reducing energy consumption through energy retrofit measures (276 and 0, respectively). Thus, CFC/HFC banks should not be neglected in LCA studies of existing buildings due to their possible significant impact on a building’s ecoprofile.
Global Hydrogen and Synfuel Exchanges in an Emission-Free Energy System
Authors: Lippkau Felix , Franzmann David , Addanki Thushara , Buchenberg Patrick , Heinrichs Heidi , Kuhn Philipp , Hamacher Thomas , Blesl Markus
Published: April 2023

This study investigates the global allocation of hydrogen and synfuels in order to achieve the well below 2 °C, preferably 1.5 °C target set in the Paris Agreement. For this purpose, TIMES Integrated Assessment Model (TIAM), a global energy system model is used. In order to investigate global hydrogen and synfuel flows, cost potential curves are aggregated and implemented into TIAM, as well as demand technologies for the end use sectors. Furthermore, hydrogen and synfuel trades are established using liquid hydrogen transport (LH2), and both new and existing technologies for synfuels are implemented. To represent a wide range of possible future events, four different scenarios are considered with different characteristics of climate and security of supply policies. The results show that in the case of climate policy, the renewable energies need tremendous expansion. The final energy consumption is shifting towards the direct use of electricity, while certain demand technologies (e.g., aviation and international shipping) require hydrogen and synfuels for full decarbonization. Due to different security of supply policies, the global allocation of hydrogen and synfuel production and exports is shifting, while the 1.5 °C target remains feasible in the different climate policy scenarios. Considering climate policy, Middle East Asia is the preferred region for hydrogen export. For synfuel production, several regions are competitive, including Middle East Asia, Mexico, Africa, South America and Australia. In the case of security of supply policies, Middle East Asia is sharing the export volume with Africa, while only minor changes can be seen in the synfuel supply.
The Apeli: An Affordable, Low-Emission and Fuel-Flexible Tier 4 Advanced Biomass Cookstove
Authors: Krüger Dennis , Mutlu Özge
Published: April 2023

Based on the decision of representatives from the West African region and feedback from locals in Togo, an advanced continuous-feed, forced-draft, biomass cookstove named “Apeli” was developed. The stove was tested in modified ISO measurements based on the ISO 19867-1:2018 standard. This included a long shutdown operation using wood pellets and short shutdown operations using wood pellets, bamboo pellets, wheat straw pellets and palm kernel shells. Due to the fast shutdown capability, the short shutdown was chosen for more realistic results using this stove type. For cold start and long shutdown operation using wood pellets, the thermal efficiency is determined as 44.1% at a 1116 W power output by emitting 0.272 g CO and 17.2 mg PM 2.5 per MJd at high load. At low load, the efficiency is 38.0% at a 526 W power output by emitting 1.1 g CO and 45.1 mg PM 2.5 per MJd. Due to a misinterpretation of the standard, the burnout duration of the tests with long shutdown is approx. 1.5 min shorter than required. Using a worst-case approximation, values for a theoretical ISO-conforming measurement were calculated and rated according to the ISO 19867-3:2018 standard. The results showed that the Apeli would correspond to Tier 4 for efficiency and PM 2.5 as well as Tier 5 for CO in high-power operation using wood pellets. The use of alternative fuels is possible, but can lead to higher emissions compared to the use of wood pellets. With regard to possibly using the biochar produced in the process for soil application, it has been demonstrated that the PAH content ensures European BioChar-Agro-Organic limitations. The first results of a field test in Togo have shown that operating and feeding the stove by the target group is easy. The required permanent presence of the user during cooking with this stove seems to have a limited influence on acceptance, which seems to primarily depend on the age of the user. Moreover, it can be concluded that the Apeli has good potential to be mass-produced locally at low costs with a reliable supply of spare parts. This can contribute not only to improving clean cooking, but also to fighting air pollution and deforestation caused by solid fuel burning due to the reduced consumption of resources in the form of fuel, especially wood.
Hydromechanical Impacts of CO2 Storage in Coal Seams of the Upper Silesian Coal Basin (Poland)
Authors: Wetzel Maria , Otto Christopher , Chen Min , Masum Shakil , Thomas Hywel , Urych Tomasz , Bezak Bartłomiej , Kempka Thomas
Published: April 2023

Deep un-mineable coal deposits are viable reservoirs for permanent and safe storage of carbon dioxide (CO2) due to their ability to adsorb large amounts of CO2 in the microporous coal structure. A reduced amount of CO2 released into the atmosphere contributes in turn to the mitigation of climate change. However, there are a number of geomechanical risks associated with the commercial-scale storage of CO2, such as potential fault or fracture reactivation, microseismic events, cap rock integrity or ground surface uplift. The present study assesses potential site-specific hydromechanical impacts for a coal deposit of the Upper Silesian Coal Basin by means of numerical simulations. For that purpose, a near-field model is developed to simulate the injection and migration of CO2, as well as the coal-CO2 interactions in the vicinity of horizontal wells along with the corresponding changes in permeability and stresses. The resulting effective stress changes are then integrated as boundary condition into a far-field numerical model to study the geomechanical response at site-scale. An extensive scenario analysis is carried out, consisting of 52 simulation runs, whereby the impacts of injection pressures, well arrangement within two target coal seams as well as the effect of different geological uncertainties (e.g., regional stress regime and rock properties) is examined for operational and post-operational scenarios. The injection-induced vertical displacements amount in maximum to 3.59 cm and 1.07 cm directly above the coal seam and at the ground surface, respectively. The results further demonstrate that neither fault slip nor dilation, as a potential consequence of slip, are to be expected during the investigated scenarios. Nevertheless, even if fault integrity is not compromised, dilation tendencies indicate that faults may be hydraulically conductive and could represent local pathways for upward fluid migration. Therefore, the site-specific stress regime has to be determined as accurately as possible by in-situ stress measurements, and also fault properties need to be accounted for an extensive risk assessment. The present study obtained a quantitative understanding of the geomechanical processes taking place at the operational and post-operational states, supporting the assessment and mitigation of environmental risks associated with CO2 storage in coal seams.
The Scheduling Research of a Wind-Solar-Hydro Hybrid System Based on a Sand-Table Deduction Model at Ultra-Short-Term Scales
Authors: Zhang Tianyao , Huang Weibin , Chen Shijun , Zhu Yanmei , Kang Fuxing , Zhou Yerong , Ma Guangwen
Published: April 2023

Establishing a wind-solar-hydro hybrid generation system is an effective way of ensuring the smooth passage of clean energy into the grid, and its related scheduling research is a complex and real-time optimization problem. Compared with the traditional scheduling method, this research investigates and improves the accuracy of the scheduling model and the flexibility of the scheduling strategy. The paper innovatively introduces a sand-table deduction model and designs a real-time adaptive scheduling algorithm to evaluate the source-load matching capability of the hybrid wind-solar-hydro system at ultra-short-term scales, and verifies it through arithmetic examples. The results show that the proposed adaptive sand-table scheduling model can reflect the actual output characteristics of the hybrid wind-solar-hydro system, track the load curve, and suppress the fluctuation of wind and solar energy, with good source-load matching capability.
Electricity Supply Unreliability and Technical Efficiency: Evidence from Listed Chinese Manufacturing Companies
Authors: Wesseh Presley K. , Zhong Yuqing , Hao Chin Hui
Published: April 2023

This study examines the extent to which electricity shortage influences technical efficiency using data of 805 listed manufacturing companies in China from 2009 to 2020 collected from the CSMAR database. To achieve the objectives of this paper, first, a stochastic frontier analysis (SFA) is used to estimate the technical efficiency (TE) score of manufacturing companies. Subsequently, the TE score is used to evaluate the electricity shortage index and other factors that are postulated to affect enterprise productivity. Two estimation methods have been adopted including ordinary least squares (OLS), which is less robust to endogeneity and instrumental variable (IV) estimation, which turns out to be more robust to endogeneity in the data. The empirical results show that, under OLS estimation, electricity shortage has a significantly negative impact on the technical efficiency of the listed manufacturing companies. However, when IV regression is implemented to address endogeneity issues in the data, electricity shortages tend to have a significantly positive impact on the technical efficiency, underscoring the importance of capturing endogeneity in the data. Extending the baseline results, this study also finds that, while the size of an enterprise may have no bearing, state-owned companies are more likely to be negatively affected by electricity shortages compared to privately owned companies. These results have significant implications for industrial policy design in China in particular, and developing countries in general. Most importantly, the results of this study underscore the importance of policies and measures to promote a shift in the ownership structure towards the private sector.
A Review of CCUS in the Context of Foams, Regulatory Frameworks and Monitoring
Authors: Orujov Alirza , Coddington Kipp , Aryana Saman A.
Published: April 2023

Greenhouse gas emission into the atmosphere is considered the main reason for the rise in Earth’s mean surface temperature. According to the Paris Agreement, to prevent the rise of the global average surface temperature beyond two degrees Celsius, global CO2 emissions must be cut substantially. While a transition to a net-zero emission scenario is envisioned by mid-century, carbon capture, utilization, and storage (CCUS) will play a crucial role in mitigating ongoing greenhouse gas emissions. Injection of CO2 into geological formations is a major pathway to enable large-scale storage. Despite significant recent technological advancements, mass deployment of these technologies still faces several technical and non-technical difficulties. This paper provides an overview of technical milestones reached thus far in CO2 capture, utilization, geological storage, monitoring technologies, and non-technical aspects such as regulatory frameworks and related policies in the US and the rest of the world. This paper describes different injection methods to store CO2 in various subsurface formations, the use of foams and the resulting potential gains in CO2 storage capacity, the role of nanoparticles for foam stabilization, and ensuring long-term storage safety. This work also addresses several safety-related aspects of geological storage and subsurface monitoring technologies that may mitigate risks associated with long-term storage.
Supercapacitor Energy Storages in Hybrid Power Supplies for Frequency-Controlled Electric Drives: Review of Topologies and Automatic Control Systems
Authors: Vladimir Polyakov , Iurii Plotnikov
Published: April 2023

This article provides an overview of the use of supercapacitor energy storage systems in adjustable AC drives for various purposes. The structures of the power section of combined (hybrid) power supplies for vehicle electric drives (hybrid electric vehicles and public transport vehicles) and general-purpose electric drives of an industrial grade (cranes, freight, and passenger lifts) are given. This review focuses on the problems inherent in conventional solutions adopted in the implementation of the power section, as well as the effect that can be obtained when using supercapacitor energy storage systems in controlled electric drives. The topologies of reversible DC/DC converters for supercapacitor energy storage devices are considered with a comparative assessment of their advantages and disadvantages, as well as their areas of application. This paper provides an overview of the structures of automatic control systems for supercapacitor energy storage devices. The composition and principles of regulating variables, the types of regulators used, and the criteria for setting regulation systems are analysed.
Numerical Study on the Mechanism of Coal and Gas Outburst in the Coal Seam Thickening Area during Mining
Authors: Liu Zhengshuai , Shu Longyong , Huo Zhonggang , Fan Yongpeng
Published: April 2023

Most coal and gas outbursts occur in the coal thickness variation zone. However, it is difficult to illustrate the mechanism of outbursts in coal thickening areas by physical simulation experiments. In this study, a coupled multi-field model, established by considering the stress–strain field, gas transport field and damage field, was used to investigate the evolution of stress, gas pressure and plastic failure zones under different variation gradients and amplitudes of coal thickness. The simulation results show that the stress peak at the coal thickening transition zone caused by mining is higher than that at the constant thickness coal seam. The stress peak at the coal thickening transition zone decreases from 18.8 MPa to 16.9 MPa with the increase in the transition zone from 0 m to 10 m under the constant coal thickness variation from 3 m to 7 m; while it increases from 16.2 MPa to 19.3 MPa with the increase in the transition zone from 2 m to 10 m under the constant coal thickness variation gradient of 45°. Similarly, the plastic deformation volume of the coal seam between the driving face and the coal thickening interface increases with the increase in the coal thickness variation gradient and amplitude. In addition, the gas pressure in the fracture declines slower in the coal thickness variation zone affected by the higher coal thickness variation gradients or amplitudes. The mechanism for outbursts occurring in the increasing coal thickness area was further discussed, and combined with the simulation results for the energy principle of outbursts. Compared with the constant thickness coal seam, the elastic energy increases from 1.85 MJ to 1.94 MJ, and the free gas expansion energy increases from 24.19 MJ to 50.57 MJ when the coal thickness varies from 3 m to 13 m within a 10 m transition zone. The variation of coal thickness causes higher stress, higher gas pressure and low coal strength, which triggers outbursts more easily. The research could provide the theoretical support to prevent and control outbursts in coal seam thickening areas during mining.