bluuebunny/crossref_metadata_2025 huggingface dataset:
Toward the Analysis of Volatile Organic Compounds from Tomato Plants (Solanum lycopersicum L.) Treated with Trichoderma virens or/and Botrytis cinerea
Authors: Nawrocka Justyna , Szymczak Kamil , Skwarek-Fadecka Monika , Małolepsza Urszula
Published: April 2023

Gray mold caused by Botrytis cinerea causes significant losses in tomato crops. B. cinerea infection may be halted by volatile organic compounds (VOCs), which may exhibit fungistatic activity or enhance the defense responses of plants against the pathogen. The enhanced VOC generation was observed in tomato (Solanum lycopersicum L.), with the soil-applied biocontrol agent Trichoderma virens (106 spores/1 g soil), which decreased the gray mold disease index in plant leaves at 72 hpi with B. cinerea suspension (1 × 106 spores/mL). The tomato leaves were found to emit 100 VOCs, annotated and putatively annotated, assigned to six classes by the headspace GCxGC TOF-MS method. In Trichoderma-treated plants with a decreased grey mold disease index, the increased emission or appearance of 2-hexenal, (2E,4E)-2,4-hexadienal, 2-hexyn-1-ol, 3,6,6-trimethyl-2-cyclohexen-1-one, 1-octen-3-ol, 1,5-octadien-3-ol, 2-octenal, octanal, 2-penten-1-ol, (Z)-6-nonenal, prenol, and acetophenone, and 2-hydroxyacetophenone, β-phellandrene, β-myrcene, 2-carene, δ-elemene, and isocaryophyllene, and β-ionone, 2-methyltetrahydrofuran, and 2-ethyl-, and 2-pentylfuran, ethyl, butyl, and hexyl acetate were most noticeable. This is the first report of the VOCs that were released by tomato plants treated with Trichoderma, which may be used in practice against B. cinerea, although this requires further analysis, including the complete identification of VOCs and determination of their potential as agents that are capable of the direct and indirect control of pathogens.
Persistent Tachypnoea in Early Infancy: A Clinical Perspective
Authors: Menahem Samuel , Sehgal Arvind , Wurzel Danielle F.
Published: April 2023

Tachypnoea in the newborn is common. It may arise from the many causes of the respiratory distress syndrome such as hyaline membrane disease, transient tachypnoea of the newborn, meconium aspiration etc. Congenital heart disease rarely presents with early tachypnoea on day one or two, in contrast to the early presentation of cyanosis, unless there is “pump” (ventricular) failure such as may occur in a cardiomyopathy/myocarditis, or as a result of severe obstruction to either ventricle. Space-occupying lesions within the chest, for example from a diaphragmatic hernia or a congenital cystic adenomatoid malformation, may present with early tachypnoea, as can a metabolic cause resulting in acidosis. The aim of this paper, however, is to focus on infants where the tachypnoea persists or develops beyond the newborn period, at times with minimal signs but occasionally with serious underlying pathology. They include causes that may have originated in the newborn but then persist; for example, arising from pulmonary hypoplasia or polycythemia. Many congenital cardiac abnormalities, particularly those causing left sided obstructive lesions, or those due to an increasing left to right shunt from large communications between the systemic and pulmonary circulations, need be considered. Respiratory causes, for example arising from aspiration, primary ciliary dyskinesia, cystic fibrosis, or interstitial lung disease, may lead to ongoing tachypnoea. Infective causes such as bronchiolitis or infantile wheeze generally are readily recognisable. Finally, there are a few infants who present with persistent tachypnoea over the first few weeks/months of their life who remain well and have normal investigations with the tachypnoea gradually resolving. How should one approach infants with persistent tachypnoea?
Numerical Simulation and Experimental Prediction of the Cladding Layer Based on the Response Surface Method
Authors: Yan Ruhai , Liu Zhuang
Published: April 2023

To study the surface morphology of laser cladding, Workbench simulated the influence of laser power and scanning speed on the width and height of the cladding layer numerically, as well as the temperature field change and residual stress distribution of the cladding layer. The simulation results reveal that the melting height and width of the cladding layer are inversely proportional to the scanning speed. When the scanning speed is from V = 3 mm/s to V = 5 mm/s, the Al cladding layer’s melting width and melting height are reduced by 15.59% and 20.8%, respectively. A positive correlation exists between the melting height and width of the cladding layer and the laser power. When the laser power changes from P = 23 w to P = 27 w, the welding width and height of the A1 cladding layer increase by 6.55% and 55.56%, respectively. The melting height and width of the second cladding layer are generally higher than those of the bottom cladding layer. The pre-experiment screening process parameters ranges are laser power P (23 w–27 w) and scanning speed (3 mm/s–8 mm/s). Based on the Minitab response surface central composite method, the most notable influence on the melting height and width is revealed to be the powder-feeding rate and laser power, respectively. The response surface analysis method establishes the regression prediction models of melting width and height. The predicted value of melting width was 95.68%, and the predicted value of melting height was 82.26%. The results show that the values of cladding width and height are within the 95% prediction interval, proving that the regression model is correct.
Informal Sector, ICT Dynamics, and the Sovereign Cost of Debt: A Machine Learning Approach
Authors: Kotzinos Apostolos , Canellidis Vasilios , Psychoyios Dimitrios
Published: April 2023

We examine the main effects of ICT penetration and the shadow economy on sovereign credit ratings and the cost of debt, along with possible second-order effects between the two variables, on a dataset of 65 countries from 2001 to 2016. The paper presents a range of machine-learning approaches, including bagging, random forests, gradient-boosting machines, and recurrent neural networks. Furthermore, following recent trends in the emerging field of interpretable ML, based on model-agnostic methods such as feature importance and accumulated local effects, we attempt to explain which factors drive the predictions of the so-called ML black box models. We show that policies facilitating the penetration and use of ICT and aiming to curb the shadow economy may exert an asymmetric impact on sovereign ratings and the cost of debt depending on their present magnitudes, not only independently but also in interaction.
The Impact of Management Practices on the Stability of Meadow Communities on a Mountain Slope
Authors: Kurhak Volodymyr , Šarūnaitė Lina , Arlauskienė Aušra , Karbivska Uliana , Tkachenko Anton
Published: April 2023

Europe is currently experiencing a huge decline in biodiversity, with the greatest reduction observed in plant species associated with grassland areas. There is therefore a need for more appropriate land management practices that do not endanger native populations. The focus of our research was to assess the modification of the species composition of the phytocenoses found in sloping meadows in the mountain–forest belt using organic and mineral fertilization and by reseeding cultural swards (with a mixture of Poaceae or Trifolium repens L.), while applying various meadow usage methods: multipurpose use (cut four times) and hay production (cut two times). The highest botanic richness (41 species from 16 families and 90% of perennial plants) was observed from the multipurpose usage of the meadow, which resulted in 28.1% more species than the haymaking usage. With regard to species stability, the most appropriate fertilization of the meadows was P30K60, regardless of the usage method. Fertilization with nitrogen fertilizers improved the yield of meadows but reduced the number of species. When meadows were reseeded with P. pratense and F. Pratensis and fertilized for haymaking, the number of families and species reduced, with a 25% decline in the number of T. repens families. This study concludes that to maintain the richness of plant species in these grasslands, farmers must receive financial subsidies to limit fertilization and plant cultivated species.
An International Investigation of Molar Incisor Hypomineralisation (iMIH) and Its Association with Dental Anomalies: Development of a Protocol
Authors: Rodd Helen D. , Nazzal Hani , Bonifacio Clarissa Calil , Ruth Choe Wei , Crombie Felicity , El Shahawy Osama , Folayan Morenike Oluwatoyin , Gambetta-Tessini Karla , Goyal Ashima , Hasmun Noren , Issa Ahmad I. , Jundi Suhad , Manton David J. , Narasimhan Srinivasan , Omar Samah , Parekh Susan , Popoola Bamidele O , Silva Mihiri , Taylor Greig , Naomi Yang Qiyue
Published: April 2023

Background: Molar incisor hypomineralisation (MIH) is a common disorder of tooth development, which has recently been found to be associated with a higher prevalence of hypodontia. The aim of this international multicentre study is to determine the association between MIH and other developmental anomalies in different populations. Methods: Investigators were trained and calibrated for the assessment of MIH and dental anomalies and ethical approvals obtained in each participating country. The study aimed to recruit 584 children with MIH and 584 children without MIH. Patients aged 7–16 years who attend specialist clinics will be invited to participate. Children will undergo a clinical examination to determine the presence and severity of MIH, using an established index. The presence of any other anomalies, affecting tooth number, morphology, or position, will be documented. Panoramic radiographs will be assessed for dental anomalies and the presence of third permanent molars. Statistical analysis, using a chi squared test and regression analysis, will be performed to determine any differences in dental anomaly prevalence between the MIH and non-MIH group and to determine any association between dental anomalies and patient characteristics. Conclusion: This large-scale study has the potential to improve understanding about MIH with benefits for patient management.
Repeated Cross-Scale Structure-Induced Feature Fusion Network for 2D Hand Pose Estimation
Authors: Guan Xin , Shen Huan , Nyatega Charles Okanda , Li Qiang
Published: April 2023

Recently, the use of convolutional neural networks for hand pose estimation from RGB images has dramatically improved. However, self-occluded keypoint inference in hand pose estimation is still a challenging task. We argue that these occluded keypoints cannot be readily recognized directly from traditional appearance features, and sufficient contextual information among the keypoints is especially needed to induce feature learning. Therefore, we propose a new repeated cross-scale structure-induced feature fusion network to learn about the representations of keypoints with rich information, ’informed’ by the relationships between different abstraction levels of features. Our network consists of two modules: GlobalNet and RegionalNet. GlobalNet roughly locates hand joints based on a new feature pyramid structure by combining higher semantic information and more global spatial scale information. RegionalNet further refines keypoint representation learning via a four-stage cross-scale feature fusion network, which learns shallow appearance features induced by more implicit hand structure information, so that when identifying occluded keypoints, the network can use augmented features to better locate the positions. The experimental results show that our method outperforms the state-of-the-art methods for 2D hand pose estimation on two public datasets, STB and RHD.
A Note on Cumulant Technique in Random Matrix Theory
Authors: Soshnikov Alexander , Wu Chutong
Published: April 2023

We discuss the cumulant approach to spectral properties of large random matrices. In particular, we study in detail the joint cumulants of high traces of large unitary random matrices and prove Gaussian fluctuation for pair-counting statistics with non-smooth test functions.
Incorporating Field Experience into International Agricultural Development Programs
Authors: Zickafoose Alexis , Wingenbach Gary
Published: April 2023

Some graduate education programs support experiential learning but do not require practical experiences for students specializing in international agriculture development. We examined U.S. land grant university graduate international agricultural education program descriptions for experiential learning requirements and found them lacking. The literature surrounding volunteerism is reviewed and examples are described. International volunteerism can fill the experience gap for future international agricultural development professionals studying at U.S. land grant institutions. Graduate students can acquire practical field experiences through short- or long-term volunteer assignments, such as those in the USAID Farmer-to-Farmer volunteer program for international agriculture development. Graduate students build their capacities by providing technical and agricultural assistance in Farmer-to-Farmer assignments, whereas host country participants enhance their knowledge, skills, and abilities to expand and increase agricultural sector productivity. Short-term international volunteer assignments help graduate students gain practical experience, improve interpersonal skills, and enhance cultural competencies. Host communities and volunteers alike benefit by engaging in intercultural exchanges that promote increased understanding of differing societies worldwide.
Personalized Learning in Virtual Learning Environments Using Students’ Behavior Analysis
Authors: Nazempour Rezvan , Darabi Houshang
Published: April 2023

In recent years, many research studies have focused on personalized e-learning. One of the most crucial parts of any learning environment is having a learning style that focuses on individual learning. In this paper, we propose an approach to personalizing learning resources based on students’ learning styles in a virtual learning environment to enhance their academic performance. Students’ interactions with the learning management system are utilized to analyze learners’ behaviors. The Felder–Silverman Learning Style Model (FSLSM) is used to map students’ interactions with online learning resources to learning style (LS) features. The learning style and demographic features are then utilized for training machine learning models to predict students’ academic performance in each quarter of courses. The most accurate prediction model for each quarter is then used to find learning style features that maximize students’ pass rates. We statistically prove that students whose actual learning style features were close enough to the ones calculated by the approach achieved better grades. To improve students’ academic performance each quarter, we suggest two strategies based on the learning style features calculated by the process.
A Simple Learning Approach for Robust Tracking Control of a Class of Dynamical Systems
Authors: Reyhanoglu Mahmut , Jafari Mohammad
Published: April 2023

This paper studies the robust tracking control problem for a class of uncertain nonlinear dynamical systems subject to unknown disturbances. A robust trajectory tracking control law is designed via a simple learning-based control strategy. In the developed design, the cost function based on the desired closed-loop error dynamics is minimized by means of gradient descent technique. A stability proof for the closed-loop nonlinear system is provided based on the pseudo-linear system theory. The learning capability of the developed robust trajectory tracking control law allows the system to mitigate the adverse effects of the uncertainties and disturbances. The numerical simulation results for a planar PPR robot are included to illustrate the effectiveness of the developed control law.
Thermal Performance of Cu Electroplated GaN/AlGaN High-Electron-Mobility Transistors with Various-Thickness Si Substrates
Authors: Horng Ray-Hua , Yeh Hsiao-Yun , Tumilty Niall
Published: April 2023

Thermal dissipation is an important issue for power devices. In this work, the impact of thermal effects on the performance of Cu electroplated GaN-based high-electron-mobility transistors (HEMTs) are considered. Electrical, thermometry and micro-Raman characterization techniques were used to correlate the effects of improved heat dissipation on device performance for GaN HEMTs with different thicknesses of Si substrate (50, 100, 150 μm), with and without an additional electroplated Cu layer. GaN HEMTs on electroplated Cu on Si (≤50 μm) demonstrate an enhanced on/off current ratio compared to bare Si substrate by a factor of ~400 (from 9.61 × 105 to 4.03 × 108). Of particular importance, surface temperature measurements reveal a much lower channel temperature for thinner HEMT devices with electroplated Cu samples compared to those without.
Numerical Simulation of Gas-Solid Two-Phase Heat Transfer in a Kaolin Cyclone Cooling System
Authors: Xu Shuai , Xie Junlin , Mei Shuxia , He Feng , Li Runguo , Deng Yuhua , Zhang Chao , Zheng Xianming
Published: April 2023

The kaolin suspension calcination technology is currently gaining attention as a new process of calcining kaolin. In this paper, the cooling system of the kaolin suspension calcination process designed by CBMI Construction Co., Ltd. is simulated using ANSYS Fluent software to analyze the velocity field and temperature field of the gas–solid two-phase flow using the Eulerian model. A compiled UDF (User-Defined Function) is used to simulate the transfer of mass and heat from the downcomer tube to the different elements. The gas, coming from the gas outlet of the cyclone, enters the next level twin-cylinder cyclone in a spiral state. The results show that the airflow in the cyclone consists of an external spiral flow from the top to the bottom and an internal spiral flow from the bottom to the top. During the downward movement of the airflow, the outer spiral flow is continuously transformed into an inner cyclonic flow. The part of the airflow that rotates close to the inner cylinder is likely to become a ‘short circuit flow’, which largely affects the separation efficiency and cooling effect of the cyclone. There is evident temperature deviation and flow deviation in the twin-cylinder cyclone, which is primarily due to the high cooling air volume and high rotation of air flow coming from the gas outlet of the previous level’s cyclone. The rotation of the air flow is the main cause of the bias temperature and bias flow phenomenon in the twin-cylinder cyclone.
A Bridgeless Cuk-BB-Converter-Based BLDCM Drive for MEV Applications
Authors: Shukla Tanmay , Nikolovski Srete
Published: April 2023

This article presents a brushless DC motor (BLDCM) drive for a maritime electric vehicle (MEV) application. The presented BLDCM drive uses a bridgeless Cuk-buckboost (BL-Cuk-BB) converter for input-side power factor (PF) improvement. The BL-Cuk-BB converter uses the buckboost converter for the negative half-cycles of the input AC voltages and the Cuk converter for the positive half-cycles. In the case of MEVs, the drive systems are generally fed by diesel engine generators (DEGs). The asymmetric BL-Cuk-BB converter is operated in a discontinuous inductor current mode (DICM) in the present work to attain better power quality. The usage of a second-order buckboost converter with a fourth-order Cuk converter results in a decrement in the net order of the system. Additionally, the input inductor of the Cuk converter also participates as the filter component along with capacitor C2 during buckboost converter operation to enhance the power quality. The total component count reduction in the BL-Cuk-BB converter is also achieved by eliminating the usage of extra/external back-feeding diodes, which are generally used in bridgeless schemes. The present scheme uses the inbuilt anti-parallel diodes for the same purpose. The lesser components requirement in the BL-Cuk-BB-converter-based BLDCM drive implies lesser cost and volume, along with greater reliability, lower conduction losses, and lower weight of the BLDCM drive, which adds to the merits of the model. The paper includes a detailed mathematical model and stability analysis using pole-zero maps and bode plots of the BL-Cuk-BB converter for each half-supply AC voltage cycle. The BL-Cuk-BB-converter-based BLDCM drive for an EV application has been developed on the MATLAB/Simulink platform for a DICM operation, and the MATLAB simulation results have been presented for validation of the BL-Cuk-BB-converter-based BLDCM drive.
Predicting Energy Consumption in Residential Buildings Using Advanced Machine Learning Algorithms
Authors: Dinmohammadi Fateme , Han Yuxuan , Shafiee Mahmood
Published: April 2023

The share of residential building energy consumption in global energy consumption has rapidly increased after the COVID-19 crisis. The accurate prediction of energy consumption under different indoor and outdoor conditions is an essential step towards improving energy efficiency and reducing carbon footprints in the residential building sector. In this paper, a PSO-optimized random forest classification algorithm is proposed to identify the most important factors contributing to residential heating energy consumption. A self-organizing map (SOM) approach is applied for feature dimensionality reduction, and an ensemble classification model based on the stacking method is trained on the dimensionality-reduced data. The results show that the stacking model outperforms the other models with an accuracy of 95.4% in energy consumption prediction. Finally, a causal inference method is introduced in addition to Shapley Additive Explanation (SHAP) to explore and analyze the factors influencing energy consumption. A clear causal relationship between water pipe temperature changes, air temperature, and building energy consumption is found, compensating for the neglect of temperature in the SHAP analysis. The findings of this research can help residential building owners/managers make more informed decisions around the selection of efficient heating management systems to save on energy bills.
Elimination of Line Overloads in a Power System Saturated with Renewable Energy Sources
Authors: Pijarski Paweł , Kacejko Piotr
Published: April 2023

The increasing number of renewable energy sources (RESs) connected to power grids contributes to the emergence of not only balancing problems but also technical ones, such as the overloading of power lines. If renewable sources with a high generation level are planned to be connected in the area under consideration, then a large number of significant overloads should be expected, especially during contingency analysis. As a rule, high-voltage networks have a mesh topology, which is why the concept of using advanced mathematical algorithms was developed, with the help of which the resulting threats can be eliminated. This article presents a proposal for a new method of eliminating line overloads and determining the currently available nodal generation levels. Its innovation is a new method of eliminating problems related to the capacity of power grids. The high efficiency of the method results from the appropriately defined response of properly selected RES sources to the state of network congestion. The problem under consideration is illustrated with the example of a modified IEEE 118-bus test network. In order to eliminate line overloads, the article proposes a two-stage approach. In the first step, the sources that are most responsible for the occurring overloads are determined. In the second step, a metaheuristic algorithm is used to solve a nonlinear optimisation problem with constraints. This task involves reducing the power generated in the sources selected in the previous step in such a way that the resulting line overloads are eliminated, and, at the same time, the total value of the curtailed generation is minimal.
Reinforcement-Learning-Based Multi-Objective Differential Evolution Algorithm for Large-Scale Combined Heat and Power Economic Emission Dispatch
Authors: Chen Xu , Fang Shuai , Li Kangji
Published: April 2023

As social and environmental issues become increasingly serious, both fuel costs and environmental impacts should be considered in the cogeneration process. In recent years, combined heat and power economic emission dispatch (CHPEED) has become a crucial optimization problem in power system management. In this paper, a novel reinforcement-learning-based multi-objective differential evolution (RLMODE) algorithm is suggested to deal with the CHPEED problem considering large-scale systems. In RLMODE, a Q-learning-based technique is adopted to automatically adjust the control parameters of the multi-objective algorithm. Specifically, the Pareto domination relationship between the offspring solution and the parent solution is used to determine the action reward, and the most-suitable algorithm parameter values for the environment model are adjusted through the Q-learning process. The proposed RLMODE was applied to solve four CHPEED problems: 5, 7, 100, and 140 generating units. The simulation results showed that, compared with four well-established multi-objective algorithms, the RLMODE algorithm achieved the smallest cost and smallest emission values for all four CHPEED problems. In addition, the RLMODE algorithm acquired better Pareto-optimal frontiers in terms of convergence and diversity. The superiority of RLMODE was particularly significant for two large-scale CHPEED problems.
Women Will Drive the Demand for EVs in the Middle East over the Next 10 Years—Lessons from Today’s Kuwait and 1960s USA
Authors: Ottesen Andri , Banna Sumayya , Alzougool Basil
Published: April 2023

The Middle East, Gulf Cooperation Council Countries (GCC), and Kuwait, in particular, are currently experiencing a similar transition as the USA in the 1970s regarding the empowerment and independence of women, fueled by a declining birth rate from four per women to less than two. In addition, the percentage of women with university degrees has been increasing at a logarithmic rate every decade since the 1960s in the USA and since 1990 in Kuwait, resulting in women comprising well over half of all university graduates. This has led to women obtaining better jobs and enjoying greater independence to make their own decisions. In the 1960s, Toyota and other Japanese car manufactures used this phenomenon to penetrate the US market, with significant success. Their selling points were lower maintenance requirements, higher reliability, safety, better environment friendliness and slicker interior designs, the last being especially adapted to women’s tastes. We believe that Chinese and Korean electric vehicle (EV) manufacturers will employ the same playbook with similar success, as the Middle East accelerates its readiness for the EV mainstream market. In this study, this prediction was supported by a quantitative questionnaire of 234 educated female Kuwaiti drivers from the ages of 18 to 40 in Kuwait regarding their preferences regarding EVs. The findings indicate that potential female buyers favor EVs for their environmental benefits, regardless of their demographics. Moreover, potential female consumers are highly willing to purchase EVs in the future under three conditions: infrastructure availability, environmental development, and affordability. We believe that this group, in particular, will present the greatest opportunity to EV manufacturers over the next 10 years.
Investigating the Parameter-Driven Cathode Gas Diffusion of PEMFCs with a Piecewise Linearization Model
Authors: Gu Siwen , Wang Jiaan , You Xinmin , Zhuang Yu
Published: April 2023

Improving mass transfer in gas diffusion layers is critical to achieving high-performance proton-exchange membrane fuel cells (PEMFCs). Leaks through the interface between the gas and the membrane electrode assembly frame have been widely investigated, and the controllability of the cathode gas diffusion has not been achieved in most studies. In this study, we develop a structural parameter to investigate the controllability of the gas diffusion mechanism in the cathode in order to improve upon the design and performance of PEMFCs. This parameter accounts for the cathode gas diffusion layer porosity and carbon loading inside the catalyst layer. It is comprehensively calculated to relax the two segments’ distribution along three directions of the coordinate axis. The experimental and simulation results show that the obtained values of the parameter vary and change during voltage stabilization. According to the results, regardless of the materials in the cathode gas diffusion layer, the same steady-state voltage is obtained when the parameter is fixed. The cell could be controllably operated for a wide range of diffusion layer thicknesses by selecting the optimal parameter.
Small Signal Modeling of LLC Converter with LED Load and Quasi-Resonant Controller Based Active Ripple Rejection
Authors: Long Xiao , Chen Dongdong
Published: April 2023

This paper has analyzed the defects of the traditional extended description function (EDF) based LLC small signal modeling method when driving light emitting diode (LED) load and proposed an accuracy improvement method. Detailed small signal model modeling methods have been deduced, and the accuracy of different modeling methods has been compared thoroughly. To suppress the second-order harmonic ripple in the direct current link-induced output current ripple, a quasi-resonant controller (QRC) is adopted to realize active ripple rejection (ARR). Considering the frequency of the second-order harmonic ripple changes with the grid voltage frequency, a single-phase software phase lock loop (SPLL) is adopted to extract the frequency of the second-order harmonic. By dynamically regulating the control parameter of the QRC according to the locked second-order frequency, output voltage ripple active rejection ability immune to grid voltage frequency deviation is obtained. Based on the deduced accurate small signal model, the digital controller is designed with stability, steady state and dynamics performance guaranteed. The accuracy of the proposed small signal model, the SPLL and the QRC-based ARR method has been verified at last.
Design Principles and Calculation Criteria for Skewed Notches in PM Motors
Authors: Ji Siwei , Li Yukai , Ou Huanyu , Tian Wenlong
Published: April 2023

The stator structure is one of the main factors affecting the electromagnetic performance of permanent magnet (PM) motors. In this paper, an in-depth study and analysis of how to reduce the cogging torque is carried out from the perspective of the stator structure. According to the theory of cogging torque synthesis, this paper presents a unified calculation formula for different PM motor skewed notch designs. This theory is verified with a 20-pole, 60-slot motor and a 20-pole, 24-slot motor, respectively. The formula worked out proved to be highly applicable. The formula is intended to address how to quickly obtain key data (skew angle, notch depth) in a skewed notch study.
Decoupling Analysis of Energy-Related Carbon Dioxide Emissions from Economic Growth in Poland
Authors: Gołaś Zbigniew
Published: April 2023

This paper addresses the conditions behind energy-related carbon dioxide (CO2) emissions in Poland following its accession to the European Union. The study analyzed some energy, fossil fuel, economic, and environmental indicators, such as energy use, CO2 emissions, driving factors, decoupling elasticity status, and decoupling effort status. It relied on the Kaya identity and Logarithmic Mean Divisia Index (LMDI) in determining the drivers of CO2 emissions. As shown by the results, between 2004 and 2020, energy consumption in Poland grew at an average annual rate of 0.8%, while fossil fuel carbon emissions declined at 0.7% per year. Energy intensity was found to be the key force behind the reduction in CO2 emissions, whereas rapid economic growth was the main driver of CO2 emissions. While other factors, i.e., carbon intensity, energy mix, and population, also contributed to reducing the emissions, they had a much smaller—if not marginal—effect. In turn, the decoupling elasticity analysis showed that Poland mostly witnessed strong decoupling states, which means a strong decoupling of CO2 emissions from economic growth. Furthermore, it follows from the decoupling effort analysis that strong decoupling effort statuses prevailed throughout the study period, suggesting that the changes in the considered factors significantly contributed to reducing CO2 emissions. However, both the decoupling elasticity indices and the decoupling effort indices revealed the presence of an adverse trend. The above means that Poland witnessed a decline both in the strength of decoupling CO2 emissions from economic growth and in the efficiency of policies and measures designed to reduce CO2 emissions.
Advocacy Coalitions and Paths to Policy Change for Promoting Energy Efficiency in European Industry
Authors: Malmborg Fredrik von , Strachan Peter A.
Published: April 2023

This paper applied the advocacy coalition framework to explore and explain the political processes creating policies to enhance energy efficiency of European Union (EU) industry. The paper used legislation on energy audits and energy management systems as a proxy for EU policy on energy efficiency in industry. Based on qualitative text analysis of EU policy documents, including a proposal to recast the energy efficiency directive, amendments to the proposal suggested by Member States, the Council and the European Parliament, and reports from negotiations, the paper identified four advocacy coalitions with different core beliefs, spanning from those that want few companies to implement energy audits or energy management systems, and that recommendations from audits should not be mandatory to implement, to those that advocate that many companies implement energy audits and management systems and that it should be mandatory to implement measures recommended in audits. It was further found that policy change followed an external shock, deliberative negotiations, and policy-oriented learning. The identification of core beliefs and advocacy coalitions will help policymakers and other stakeholders become more aware of their own and others’ values on energy efficiency and how these could be changed. As important was the differentiation of deep core beliefs, policy core beliefs and secondary beliefs. Which beliefs can be easily changed, which cannot?
New Strategy on Power Absorption of a Concentric Two-Body Wave Energy Converter
Authors: Natarajan Senthil Kumar , Cho Ilhyoung
Published: April 2023

The wave energy converter (WEC) system, which extracts electricity through the relative heave motion of two concentric cylinders, comprises an inner cylinder and a torus-type outer cylinder sliding along the inner cylinder. To maximize the relative heave motion between two cylinders, the natural frequencies of the two cylinders must be precisely tuned to resonate and be situated on each side of the peak frequency of the wave spectrum. However, the demerit of this strategy is that it demands a deep draft of each cylinder for tuning, and a large-scale PTO damping device is necessary for mechanical power amplified by resonance. As an alternative to efficient and stable WECs, we adopt a new strategy in which the outer cylinder follows the incoming waves and the motion of the inner one is restricted to be minimal using a heave disk. The viscous damping due to formation of vortices at the disk edge is realized by the drag force in the Morison equation. The developed hydrodynamic model of two-body WEC based on a matched eigenfunction expansion method (MEEM) is applied to irregular waves characterized by significant wave height and peak period. It is found that the present two-body WEC with heave disk produces wave energy stably across a wide range of wave frequencies compared to the previous two-body WECs using resonance.
Links between the Energy Intensity of Public Urban Transport, Regional Economic Growth and Urbanisation: The Case of Poland
Authors: Kłos-Adamkiewicz Zuzanna , Szaruga Elżbieta , Gozdek Agnieszka , Kogut-Jaworska Magdalena
Published: April 2023

The article concerns the verification of links between the energy intensity of public urban transport, regional economic development and urbanisation in the light of sustainable development challenges and club convergence processes. Three research questions were formulated in the article: (1) Does the regional economic development of voivodeships affect the energy intensity of public urban transport? (2) Does urbanisation shape energy consumption patterns in public urban transport (and are there agglomeration effects)? (3) Does the level of urbanisation of voivodeships depend on their regional level? The study covered 16 subregions of Poland from 2010 to 2020. A spatial dynamic exploration of the relationships between energy intensity patterns of public urban transport and the phenomenon of urbanisation and regional economic development was carried out. Panel models of vector autoregression and panel causality testing were used. The influence of the economic development of regions and the level of urbanisation on energy intensity patterns of public urban transport was confirmed. The link between economic development and the process of urbanisation was identified. An additional effect was noticed (novelty knowledge), i.e., there is a delayed club convergence between voivodeships in the area of energy intensity of public urban transport, regional economic development and urbanisation (polyconvergence).
The Differential Effects of Oil Prices on the Development of Renewable Energy in Oil-Importing and Oil-Exporting Countries in Africa
Authors: Tambari Ishaya Jonah Tegina , Failler Pierre , Jaffry Shabbar
Published: April 2023

The shift to renewable sources of energy has become a critical economic priority in African countries due to energy challenges. However, investors in the development of renewable energy face problems with decision making due to the existence of multiple criteria, such as oil prices and the associated macroeconomic performance. This study aims to analyze the differential effects of international oil prices and other macroeconomic factors on the development of renewable energy in both oil-importing and oil-exporting countries in Africa. The study uses a panel vector error correction model (P-VECM) to analyze data from five net oil exporters (Algeria, Angola, Egypt, Libya and Nigeria) and five net oil importers (Kenya, Ethiopia, Congo, Mozambique and South Africa). The study finds that higher oil prices positively affect the development of renewable energy in oil-importing countries by making renewable energy more economically competitive. Economic growth is also identified as a major driver of the development of renewable energy. While high-interest rates negatively affect the development of renewable energy in oil-importing countries, it has positive effects in oil-exporting countries. Exchange rates play a crucial role in the development of renewable energy in both types of countries with a negative effect in oil-exporting countries and a positive effect in oil-importing countries. The findings of this study suggest that policymakers should take a holistic approach to the development of renewable energy that considers the complex interplay of factors, such as oil prices, economic growth, interest rates, and exchange rates.
Geochemical and Microstructural Characteristics of Clay Minerals and Their Effects on the Pore Structure of Coal-Measure Shale: A Case Study in Qinshui Basin, China
Authors: Li Kunjie , Kong Shaoqi , Liang Yanxia , Ali Muhammad , Zhang Yongfa , Zhao Yuqiong
Published: April 2023

As the essential component of shale, clay minerals have a vital influence on the pore structure and the gas content of reservoirs. To investigate the compositional characteristics of coal-measure shale and its effects on pore structure, a total of thirteen Taiyuan formation shale samples were collected from the Qinshui Basin and were analyzed using a combination of X-ray diffraction analysis, X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy (FE-SEM), polarized optical microscopy, and field emission scanning electron microscopy. The results show that the principal minerals of the samples are quartz, kaolinite, and illite. Most of the kaolinite was an original terrigenous detrital material with low crystallinity and a low degree of ordering, whereas the illite was mainly composed of 1Md resulting from diagenesis. Clay minerals developed slits, irregularly-shaped or multisized pores during diagenesis, which can be classed into interlayered pores, intergranular pores, and microfractures. Eight micro-morphological forms of clay minerals were summarized based on FE-SEM observations, such as compacted, parallel, bent, tilted, mutually supporting structures, etc., which are mainly formed by the mechanical compaction of clay minerals with different sizes, shapes, and contact relationships. The diversity and complexity of the micro-morphological forms of clay minerals contribute to the strong heterogeneity, low porosity and high permeability anisotropy of shale.
Pore Structure and Fractal Characteristics of Coal-Measure Sedimentary Rocks Using Nuclear Magnetic Resonance (NMR) and Mercury Intrusion Porosimetry (MIP)
Authors: Zhang Na , Wang Shuaidong , Xun Xingjian , Wang Huayao , Sun Xiaoming , He Manchao
Published: April 2023

Analyzing and mastering the fractal features of coal-measure sedimentary rocks is crucial for accurately describing the pore structure of coalbed methane resources. In this work, mercury intrusion porosimetry (MIP) and nuclear magnetic resonance (NMR) are performed on coal-measure sedimentary rocks (i.e., shale, mudstone, and sandstone) to analyze their pore structure. Pore size distributions (PSDs) and the multifractal dimensions of the investigated samples are discussed. Moreover, multivariable linear regression models of multifractal dimensions are established through a comprehensive analysis of multifractal characteristics. The results show that sandstone (SS-1) and clay rocks are dominated by nanopores of 0.01 to 1 μm, while sandstone (SS-2) is mostly mesopores and macropores in the range of 1 to 10 μm. The fractal characteristics of the investigated rock samples show a prominent multifractal characteristic, in which DA reflects the surface structure of micropores, while DS represents the pore structure of macropores. Multifractal dimension is affected by many factors, in which the DA is greatly influenced by the pore surface features and mineral components and the DS by average pore diameters. Moreover, multivariate linear regression models of adsorption pore and seepage pore are established, which have a better correlation effect on the multifractal dimension.
Correlation Study between Quality and Sensory Characteristics of Kelp Paste by Aspergillus oryzae and Aspergillus niger during Fermentation
Authors: Zhong Zhihong , Wang Zhiyun , Zhang Yi , Zheng Baodong , Zeng Hongliang
Published: April 2023

In order to clarify the relationship between quality and sensory characteristics of kelp paste during fermentation, this study analyzed the quality and sensory characteristics of kelp paste through physicochemical indexes, nutritional components, electronic nose and electronic tongue. The results showed that with the extension of fermentation time, the contents of amino nitrogen, total acid, ammonium salt and ash increased gradually, while the pH value, moisture, fat, protein and carbohydrate decreased gradually. Short-chain alkanes such as nitrogen oxides and methane were the main causes of odor. Freshness, salinity and richness were the main indexes of kelp paste taste. Many quality indexes, such as amino nitrogen and protein, were significantly related to the odor sensor, which can better reflect the odor produced in the fermentation process of kelp paste. There was a significant correlation between quality indicators and important taste indicators such as umami, richness and salty taste, which can better reflect the taste of kelp paste during fermentation. To sum up, there was a significant correlation between the quality characteristics and sensory quality of kelp paste, so the relationship between quality characteristics and sensory characteristics in kelp paste can be clarified.
Measuring Food Insecurity: The Problem with Semantics
Authors: Sumsion Rachel M. , June Haylie M. , Cope Michael R.
Published: April 2023

Rising rates of hunger and food insecurity have sparked a major re-evaluation of all aspects of food systems. Because of the multifaceted nature of food insecurity, however, determining what actions should be taken is challenging, especially since reevaluation efforts are led by experts from several disciplines and there is no consensus about which indicators should be used and how they should be measured. Confusion surrounding the meaning of the terms ‘food security’ and ‘food insecurity’ has contributed to this lack of consensus. As indicators inform action, such confusion has slowed those committed to alleviating hunger in identifying the most pressing targets. This review highlights (1) the importance of clearly defining food security and food insecurity and (2) how such definitions affect measures of food insecurity in the United States. While some might say that definitions are an issue of the past or a trivial matter of semantics, we believe that the world’s present rates of hunger and malnutrition are attributable, at least in part, to the lack of consensus on these definitions and their accompanying measurements and indicators. Although the present review can be helpful to academics and policy makers, the primary purpose is to be a resource to those involved in the day-to-day production of food, such as ranchers and farmers by providing an overview of definitions, indicators, and measurements used when discussing food security.
Insight into the Effects of Drying Methods on Lanzhou Lily Rehydration
Authors: Zhang Xinyu , Xue Lu , Wu Zijian , Zhang Wen , Zhang Han , Zhao Cuiyu , Liu Dandan
Published: April 2023

This study investigated the effects of drying methods (hot air drying (HAD), microwave vacuum drying (MVD), and vacuum freeze drying (VFD)) on the rehydration performance (RP) of dried Lanzhou lily scales (LLS). Rehydration rate and water migration showed that MVD had the best RP, followed by VFD, while HAD had the worst. The results of additional morphology observation using scanning electron microscopy (SEM) and micro X-ray computed tomography (CT) imaging showed that both MVD and VFD created more channels in more porous structures, which facilitated their better RP than that by HAD. The results also revealed the spatial structure diversity (including pores, channels size, and internal network) of each dried Lanzhou lily scale group. In addition, studies analyzed how drying techniques affected the physiochemical properties of lily starch, including its water solubility, pasting profiles, and starch particle morphology. The findings indicated that when MVD was in operation, partial gelatinization in lily starch was brought about by thermal effects, allowing MVDS crystals to change from B-type to V-type and causing MVDS to have better water absorption ability. Consequently, despite the fact that MVD’s desiccated lilies have a lower porous structure and thinner channels than VFD’s, MVD has a higher RP than VFD.