The present study focused on the quantitative determination of active compounds, antioxidant and antibacterial activities of leaf extracts of different Sonneratia species. The tested species including Sonneratia alba (SA), Sonneratia caseolaris (SC), and Sonneratia ovata Backer (SO) were collected from Can Gio Mangrove Forest, Vietnam. The methanol extract of SA leaves was found to contain the highest content of total flavonoids, total phenolics and gallic acid (4344.16 ± 51.78 μg/g dry mass). The highest luteolin‐7‐O‐glucoside and luteolin amounts (5963.28 ± 59.77 and 234.33 ± 10.41 μg/g dry mass, respectively) were found in the methanol extract of SC leaves according to HPLC‐DAD analysis. The methanol extracts of all three species exhibited strong DPPH radical scavenging activity while the ethanol extracts provided strong antibacterial activity against Staphylococcus aureus, Salmonella typhimurium, and Escherichia coli. By fractionating the extracts over a SiO2 column using CHCl3: EA: MeOH gradients, the fractions containing high purity luteolin and luteolin‐7‐glucoside from SC and high purity luteolin from SO were collected. Moreover, all fractions demonstrated significant DPPH free radical scavenging ability but the fraction enriched in gallic acid showed the highest activity. These findings show that SA is a promising source of gallic acid while SC can be potentially used for the extraction and isolation of luteolin‐7‐glucoside.
{"title":"Analysis of active compounds and bioactivity of leaves extracts of Sonneratia species","authors":"Lam Nguyen, Thuong Thi Nguyen, Hoa Ngoc Nguyen, Quynh Thi Phuong Bui","doi":"10.1002/eng2.12870","DOIUrl":"https://doi.org/10.1002/eng2.12870","url":null,"abstract":"The present study focused on the quantitative determination of active compounds, antioxidant and antibacterial activities of leaf extracts of different Sonneratia species. The tested species including Sonneratia alba (SA), Sonneratia caseolaris (SC), and Sonneratia ovata Backer (SO) were collected from Can Gio Mangrove Forest, Vietnam. The methanol extract of SA leaves was found to contain the highest content of total flavonoids, total phenolics and gallic acid (4344.16 ± 51.78 μg/g dry mass). The highest luteolin‐7‐O‐glucoside and luteolin amounts (5963.28 ± 59.77 and 234.33 ± 10.41 μg/g dry mass, respectively) were found in the methanol extract of SC leaves according to HPLC‐DAD analysis. The methanol extracts of all three species exhibited strong DPPH radical scavenging activity while the ethanol extracts provided strong antibacterial activity against Staphylococcus aureus, Salmonella typhimurium, and Escherichia coli. By fractionating the extracts over a SiO2 column using CHCl3: EA: MeOH gradients, the fractions containing high purity luteolin and luteolin‐7‐glucoside from SC and high purity luteolin from SO were collected. Moreover, all fractions demonstrated significant DPPH free radical scavenging ability but the fraction enriched in gallic acid showed the highest activity. These findings show that SA is a promising source of gallic acid while SC can be potentially used for the extraction and isolation of luteolin‐7‐glucoside.","PeriodicalId":11735,"journal":{"name":"Engineering Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140435939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In contrast to single‐phase materials the manufacturing process of composites creates multiscale interfaces among constituent materials and between laminar multilayers. Targeting the interfaces in these composite structures, this paper presents a perspective study on the impact safety of potential future composite rail vehicles. The aim is to conceptually explore the key role of interfacial discontinuities of composite material structures as they are a critical issue affecting the impact performance of future composite rail vehicles. Following a theoretical description, the issues are addressed in two parts. First, composite materials are characteristically analyzed from the perspective of their interfacial discontinuities within the materials and between the laminate multilayers to identify their influence. Second, the structural conditions required for crashworthiness are determined in relation to the dual requirements of global stability and local deformability for efficient energy absorption. The key findings are: (1) The interfacial discontinuities of the material phases and the designed structural assemblies need to be tailored for crashworthiness performance and (2) Global stability and locally deformability are the key dual requirements for the energy absorbing progressive deformations that are essential for application of composite for crashworthiness of rail vehicles. The research conceptually explores a key issue of the impact mechanics of composite structures from the perspective of impact safety of composite rail vehicles.
{"title":"The effect of composite materials interfacial discontinuities on the impact safety of future composite rail vehicles","authors":"Xiangdong Xue, Mark Robinson, Wei Zhang","doi":"10.1002/eng2.12868","DOIUrl":"https://doi.org/10.1002/eng2.12868","url":null,"abstract":"In contrast to single‐phase materials the manufacturing process of composites creates multiscale interfaces among constituent materials and between laminar multilayers. Targeting the interfaces in these composite structures, this paper presents a perspective study on the impact safety of potential future composite rail vehicles. The aim is to conceptually explore the key role of interfacial discontinuities of composite material structures as they are a critical issue affecting the impact performance of future composite rail vehicles. Following a theoretical description, the issues are addressed in two parts. First, composite materials are characteristically analyzed from the perspective of their interfacial discontinuities within the materials and between the laminate multilayers to identify their influence. Second, the structural conditions required for crashworthiness are determined in relation to the dual requirements of global stability and local deformability for efficient energy absorption. The key findings are: (1) The interfacial discontinuities of the material phases and the designed structural assemblies need to be tailored for crashworthiness performance and (2) Global stability and locally deformability are the key dual requirements for the energy absorbing progressive deformations that are essential for application of composite for crashworthiness of rail vehicles. The research conceptually explores a key issue of the impact mechanics of composite structures from the perspective of impact safety of composite rail vehicles.","PeriodicalId":11735,"journal":{"name":"Engineering Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140441914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
So far shape memory alloys (SMA) are mostly characterized by their thermo‐mechanical behavior due to the underlying thermal effect. In technical applications however, where their benefits like low weight and compact design become relevant, they are activated electrically. This work presents methods for a thorough and systematic characterization of SMA wire samples under Joule heating with the focus on aspects relevant for applications. The goal is to achieve a precise understanding of the sensor and actuator properties of SMA wire samples with different trainings under varying loads. All experiments are conducted on a custom designed test bench with a commercially available NiTi wire with 72 μm diameter, which enables the direct comparisons of tensile tests to actuation tests. The characterization consists of tensile tests and actuator tests with varying load and heating power for differently trained wire samples. The results vividly represent the influence of heating power, training and changing loads on stroke output, working point and the functional stability of SMA actuator wires. Especially, the evolution of the resistance signal and the influence of the R‐phase on self‐sensing is discussed. The proposed method enables to compare and choose the best suitable alloy with a fitting training for a desired application.
迄今为止，形状记忆合金（SMA）的主要特点是由于潜在的热效应而产生的热机械行为。但在技术应用中，由于其重量轻、设计紧凑等优点，它们可以通过电激活。本研究介绍了在焦耳加热条件下对 SMA 金属丝样品进行全面系统表征的方法，重点关注与应用相关的方面。目的是精确了解 SMA 金属丝样品在不同负载下的传感器和致动器特性。所有实验都是在定制设计的测试台上进行的，使用的是市场上销售的直径为 72 μm 的镍钛金属丝，这样就可以将拉伸测试与致动测试进行直接比较。表征包括拉伸试验和致动器试验，对不同训练有素的金属丝样品施加不同的载荷和加热功率。结果生动地反映了加热功率、训练和负载变化对 SMA 执行器导线的冲程输出、工作点和功能稳定性的影响。特别是讨论了电阻信号的演变和 R 相对自感应的影响。通过所提出的方法，可以比较并选择最合适的合金，并为所需应用提供合适的训练。
{"title":"Electro‐thermo‐mechanical characterization of shape memory alloy wires for actuator and sensor applications—Part 1: The effects of training","authors":"Dominik Scholtes, S. Seelecke, Paul Motzki","doi":"10.1002/eng2.12867","DOIUrl":"https://doi.org/10.1002/eng2.12867","url":null,"abstract":"So far shape memory alloys (SMA) are mostly characterized by their thermo‐mechanical behavior due to the underlying thermal effect. In technical applications however, where their benefits like low weight and compact design become relevant, they are activated electrically. This work presents methods for a thorough and systematic characterization of SMA wire samples under Joule heating with the focus on aspects relevant for applications. The goal is to achieve a precise understanding of the sensor and actuator properties of SMA wire samples with different trainings under varying loads. All experiments are conducted on a custom designed test bench with a commercially available NiTi wire with 72 μm diameter, which enables the direct comparisons of tensile tests to actuation tests. The characterization consists of tensile tests and actuator tests with varying load and heating power for differently trained wire samples. The results vividly represent the influence of heating power, training and changing loads on stroke output, working point and the functional stability of SMA actuator wires. Especially, the evolution of the resistance signal and the influence of the R‐phase on self‐sensing is discussed. The proposed method enables to compare and choose the best suitable alloy with a fitting training for a desired application.","PeriodicalId":11735,"journal":{"name":"Engineering Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139959282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The transition from traditional to digital payment platforms is reshaping domestic revenue mobilization, with significant impacts on sectors like agriculture, health, business, education and economy. This transition, while presenting both challenges and opportunities, has the potential to foster economic growth and boost revenue mobilization. This paper investigates how digital taxation or electronic levy (e‐levy) has shaped mobile money (MoMo) adoption in Ghana since the introduction of e‐levy on digital financial transactions. The underlying theories supporting this study include the Technology Acceptance Model (TAM), Social Norm Theory (SNT), and Expectancy‐Confirmation Theory (ECT). A cross‐sectional design was employed, and data was collected from 206 participants (mobile network subscribers) through a self‐administered online survey conducted and applied a partial least square structural equation modeling technique. The findings indicate that inherent innovativeness, the structure of the tax, and social tax compliance norms significantly influence citizens' compliance attitudes towards e‐levy in the context of a developing country. Conversely, the study found that potential taxpayers' attitudes towards e‐levy do not determine their intention to pay (actual use) e‐levy. In this respect, recommendations to drive the digital taxation agenda among government revenue agencies in developing countries are (i) continuous inherent innovativeness on the part of the government, (ii) ensuring compliance attitudes towards e‐levy, (iii) proper structuring of the tax components and (iv) ensuring ease of use of the system. These findings provide governments and revenue agencies, particularly those in developing countries, with valuable insights into citizens' behavioral change towards digital taxation on MoMo transactions. An effective convergence of the determinants discussed in this research would expedite government mobilization efforts for electronic levies and promote development.
{"title":"New policies, new behaviors: How digital taxation shapes mobile money use in Ghana","authors":"Kingsley Ofosu-Ampong","doi":"10.1002/eng2.12860","DOIUrl":"https://doi.org/10.1002/eng2.12860","url":null,"abstract":"The transition from traditional to digital payment platforms is reshaping domestic revenue mobilization, with significant impacts on sectors like agriculture, health, business, education and economy. This transition, while presenting both challenges and opportunities, has the potential to foster economic growth and boost revenue mobilization. This paper investigates how digital taxation or electronic levy (e‐levy) has shaped mobile money (MoMo) adoption in Ghana since the introduction of e‐levy on digital financial transactions. The underlying theories supporting this study include the Technology Acceptance Model (TAM), Social Norm Theory (SNT), and Expectancy‐Confirmation Theory (ECT). A cross‐sectional design was employed, and data was collected from 206 participants (mobile network subscribers) through a self‐administered online survey conducted and applied a partial least square structural equation modeling technique. The findings indicate that inherent innovativeness, the structure of the tax, and social tax compliance norms significantly influence citizens' compliance attitudes towards e‐levy in the context of a developing country. Conversely, the study found that potential taxpayers' attitudes towards e‐levy do not determine their intention to pay (actual use) e‐levy. In this respect, recommendations to drive the digital taxation agenda among government revenue agencies in developing countries are (i) continuous inherent innovativeness on the part of the government, (ii) ensuring compliance attitudes towards e‐levy, (iii) proper structuring of the tax components and (iv) ensuring ease of use of the system. These findings provide governments and revenue agencies, particularly those in developing countries, with valuable insights into citizens' behavioral change towards digital taxation on MoMo transactions. An effective convergence of the determinants discussed in this research would expedite government mobilization efforts for electronic levies and promote development.","PeriodicalId":11735,"journal":{"name":"Engineering Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139961223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Udaya Devadiga, Peter Fernandes, A. Buradi, Addisu Frinjo Emma
In order to improve the wear and frictional behavior of the aluminum metal matrix composites, carbon nanotube, and fly ash were added as reinforcements. Powder metallurgy technique was used to fabricate the hybrid metal matrix composites. Experimentations were carried out using pin on disc type wear test rig. The analyzed experimental results showed that, in comparison to the pure aluminum and mono reinforcement combination, the wear loss and coefficient of friction of hybrid metal matrix composites were greatly reduced. It was noted that compared to pure aluminum wear loss was decreased to 89.58%, 86.97%, 83.3% by adding 0.25, 0.5, 0.75 wt% carbon nanotube (CNT), respectively. By the addition of 4, 8 and 16 wt% FA to pure Al wear loss was decreased to 83.85%, 89.58%, and 78.12%, respectively. It was also noted that compared to Al/8 wt% FA mono reinforced composites, wear loss was decreased to 77%, 71.26%, and 53.22% with the addition of 0.25, 0.5, 0.75 wt% CNT, respectively. With the addition of 4, 8, 16 wt% FA, wear loss decreased to 81%, 88%, and 75% over Al/0.25 wt% CNT composites, respectively. The microstructural study of the worn‐out surfaces revealed low abrasive and adhesive wear by the presence of carbon nanotubes and fly ash in aluminum metal matrix. The reinforcing mechanisms of the wear and frictional properties were also discussed.
{"title":"Significance of addition of carbon nanotubes and fly ash on the wear and frictional performance of aluminum metal matrix composites","authors":"Udaya Devadiga, Peter Fernandes, A. Buradi, Addisu Frinjo Emma","doi":"10.1002/eng2.12865","DOIUrl":"https://doi.org/10.1002/eng2.12865","url":null,"abstract":"In order to improve the wear and frictional behavior of the aluminum metal matrix composites, carbon nanotube, and fly ash were added as reinforcements. Powder metallurgy technique was used to fabricate the hybrid metal matrix composites. Experimentations were carried out using pin on disc type wear test rig. The analyzed experimental results showed that, in comparison to the pure aluminum and mono reinforcement combination, the wear loss and coefficient of friction of hybrid metal matrix composites were greatly reduced. It was noted that compared to pure aluminum wear loss was decreased to 89.58%, 86.97%, 83.3% by adding 0.25, 0.5, 0.75 wt% carbon nanotube (CNT), respectively. By the addition of 4, 8 and 16 wt% FA to pure Al wear loss was decreased to 83.85%, 89.58%, and 78.12%, respectively. It was also noted that compared to Al/8 wt% FA mono reinforced composites, wear loss was decreased to 77%, 71.26%, and 53.22% with the addition of 0.25, 0.5, 0.75 wt% CNT, respectively. With the addition of 4, 8, 16 wt% FA, wear loss decreased to 81%, 88%, and 75% over Al/0.25 wt% CNT composites, respectively. The microstructural study of the worn‐out surfaces revealed low abrasive and adhesive wear by the presence of carbon nanotubes and fly ash in aluminum metal matrix. The reinforcing mechanisms of the wear and frictional properties were also discussed.","PeriodicalId":11735,"journal":{"name":"Engineering Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139838472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Udaya Devadiga, Peter Fernandes, A. Buradi, Addisu Frinjo Emma
In order to improve the wear and frictional behavior of the aluminum metal matrix composites, carbon nanotube, and fly ash were added as reinforcements. Powder metallurgy technique was used to fabricate the hybrid metal matrix composites. Experimentations were carried out using pin on disc type wear test rig. The analyzed experimental results showed that, in comparison to the pure aluminum and mono reinforcement combination, the wear loss and coefficient of friction of hybrid metal matrix composites were greatly reduced. It was noted that compared to pure aluminum wear loss was decreased to 89.58%, 86.97%, 83.3% by adding 0.25, 0.5, 0.75 wt% carbon nanotube (CNT), respectively. By the addition of 4, 8 and 16 wt% FA to pure Al wear loss was decreased to 83.85%, 89.58%, and 78.12%, respectively. It was also noted that compared to Al/8 wt% FA mono reinforced composites, wear loss was decreased to 77%, 71.26%, and 53.22% with the addition of 0.25, 0.5, 0.75 wt% CNT, respectively. With the addition of 4, 8, 16 wt% FA, wear loss decreased to 81%, 88%, and 75% over Al/0.25 wt% CNT composites, respectively. The microstructural study of the worn‐out surfaces revealed low abrasive and adhesive wear by the presence of carbon nanotubes and fly ash in aluminum metal matrix. The reinforcing mechanisms of the wear and frictional properties were also discussed.
{"title":"Significance of addition of carbon nanotubes and fly ash on the wear and frictional performance of aluminum metal matrix composites","authors":"Udaya Devadiga, Peter Fernandes, A. Buradi, Addisu Frinjo Emma","doi":"10.1002/eng2.12865","DOIUrl":"https://doi.org/10.1002/eng2.12865","url":null,"abstract":"In order to improve the wear and frictional behavior of the aluminum metal matrix composites, carbon nanotube, and fly ash were added as reinforcements. Powder metallurgy technique was used to fabricate the hybrid metal matrix composites. Experimentations were carried out using pin on disc type wear test rig. The analyzed experimental results showed that, in comparison to the pure aluminum and mono reinforcement combination, the wear loss and coefficient of friction of hybrid metal matrix composites were greatly reduced. It was noted that compared to pure aluminum wear loss was decreased to 89.58%, 86.97%, 83.3% by adding 0.25, 0.5, 0.75 wt% carbon nanotube (CNT), respectively. By the addition of 4, 8 and 16 wt% FA to pure Al wear loss was decreased to 83.85%, 89.58%, and 78.12%, respectively. It was also noted that compared to Al/8 wt% FA mono reinforced composites, wear loss was decreased to 77%, 71.26%, and 53.22% with the addition of 0.25, 0.5, 0.75 wt% CNT, respectively. With the addition of 4, 8, 16 wt% FA, wear loss decreased to 81%, 88%, and 75% over Al/0.25 wt% CNT composites, respectively. The microstructural study of the worn‐out surfaces revealed low abrasive and adhesive wear by the presence of carbon nanotubes and fly ash in aluminum metal matrix. The reinforcing mechanisms of the wear and frictional properties were also discussed.","PeriodicalId":11735,"journal":{"name":"Engineering Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139778629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Georgia de Souza Assumpção, Carolina Maia dos Santos, Daniele de Lima Campello, Leonardo Silva de Lima, Alexandre de Carvalho Castro
The paper analyzes how to improve the teaching of Operational Research, focusing on distance learning courses where professors and students are separated through space and time. This case study was done in a public Industrial Engineering undergraduate course, and the work structure is divided into three main parts: an exploratory‐descriptive documentary analysis, application of free software, and evaluation of learning. The authors showed the feasibility of using the SageMath tool in the teaching‐learning process. The study revealed the importance of developing alternative solutions to educational realities marked by economic and financial constraints, where structure teaching with free software is a ruling factor once Engineering education is not a similar global event everywhere. Distance learning is a phenomenon that has been growing over the last 20 years in Brazil, but this was one of the first experiences with the use of SageMath. So, it can serve as a reference for countries with socioeconomic conditions similar to Brazil. Also, this case study can help other professors to enhance their teaching in a distance learning context even in scarcity scenarios of educational resources. The software implementation would be justified in part of the groups studied.
{"title":"A proposal of teaching operational research in online contexts: An experience with SageMath in Brazil","authors":"Georgia de Souza Assumpção, Carolina Maia dos Santos, Daniele de Lima Campello, Leonardo Silva de Lima, Alexandre de Carvalho Castro","doi":"10.1002/eng2.12863","DOIUrl":"https://doi.org/10.1002/eng2.12863","url":null,"abstract":"The paper analyzes how to improve the teaching of Operational Research, focusing on distance learning courses where professors and students are separated through space and time. This case study was done in a public Industrial Engineering undergraduate course, and the work structure is divided into three main parts: an exploratory‐descriptive documentary analysis, application of free software, and evaluation of learning. The authors showed the feasibility of using the SageMath tool in the teaching‐learning process. The study revealed the importance of developing alternative solutions to educational realities marked by economic and financial constraints, where structure teaching with free software is a ruling factor once Engineering education is not a similar global event everywhere. Distance learning is a phenomenon that has been growing over the last 20 years in Brazil, but this was one of the first experiences with the use of SageMath. So, it can serve as a reference for countries with socioeconomic conditions similar to Brazil. Also, this case study can help other professors to enhance their teaching in a distance learning context even in scarcity scenarios of educational resources. The software implementation would be justified in part of the groups studied.","PeriodicalId":11735,"journal":{"name":"Engineering Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139840777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Georgia de Souza Assumpção, Carolina Maia dos Santos, Daniele de Lima Campello, Leonardo Silva de Lima, Alexandre de Carvalho Castro
The paper analyzes how to improve the teaching of Operational Research, focusing on distance learning courses where professors and students are separated through space and time. This case study was done in a public Industrial Engineering undergraduate course, and the work structure is divided into three main parts: an exploratory‐descriptive documentary analysis, application of free software, and evaluation of learning. The authors showed the feasibility of using the SageMath tool in the teaching‐learning process. The study revealed the importance of developing alternative solutions to educational realities marked by economic and financial constraints, where structure teaching with free software is a ruling factor once Engineering education is not a similar global event everywhere. Distance learning is a phenomenon that has been growing over the last 20 years in Brazil, but this was one of the first experiences with the use of SageMath. So, it can serve as a reference for countries with socioeconomic conditions similar to Brazil. Also, this case study can help other professors to enhance their teaching in a distance learning context even in scarcity scenarios of educational resources. The software implementation would be justified in part of the groups studied.
{"title":"A proposal of teaching operational research in online contexts: An experience with SageMath in Brazil","authors":"Georgia de Souza Assumpção, Carolina Maia dos Santos, Daniele de Lima Campello, Leonardo Silva de Lima, Alexandre de Carvalho Castro","doi":"10.1002/eng2.12863","DOIUrl":"https://doi.org/10.1002/eng2.12863","url":null,"abstract":"The paper analyzes how to improve the teaching of Operational Research, focusing on distance learning courses where professors and students are separated through space and time. This case study was done in a public Industrial Engineering undergraduate course, and the work structure is divided into three main parts: an exploratory‐descriptive documentary analysis, application of free software, and evaluation of learning. The authors showed the feasibility of using the SageMath tool in the teaching‐learning process. The study revealed the importance of developing alternative solutions to educational realities marked by economic and financial constraints, where structure teaching with free software is a ruling factor once Engineering education is not a similar global event everywhere. Distance learning is a phenomenon that has been growing over the last 20 years in Brazil, but this was one of the first experiences with the use of SageMath. So, it can serve as a reference for countries with socioeconomic conditions similar to Brazil. Also, this case study can help other professors to enhance their teaching in a distance learning context even in scarcity scenarios of educational resources. The software implementation would be justified in part of the groups studied.","PeriodicalId":11735,"journal":{"name":"Engineering Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139780897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The biochemical pathway for propionic acid (PA) production is an interesting alternative that can include the utilization of biomass as feedstock. This study evaluated the utilization of Agave bagasse (AB), a lignocellulosic residue, to produce PA by Propionibacterium acidipropinici in batch systems (125 mL‐hermetic bottles and 1000 mL‐bioreactor). The process included a steam explosion pretreatment at 142°C for 15 min and enzymatic hydrolysis, where solid loading (2.75% and 5% in pretreatment and 2.5%, 3.75%, and 5% in enzymatic hydrolysis) was evaluated. Furthermore, the enzymatic concentrations of 18.3 filter paper unit (FPU)/gAB (1×) of Cellic® CTec2 and 1.5× and 3× were tested. The yields of total carbohydrates (TC) obtained at the two solid loadings tested in the pretreatment were statistically similar, but the 3x enzymatic concentration enhanced the yields of TC, glucose, and xylose (0.23 ± 0.01, 0.15 ± 0.01 and 0.03 ± 0.01 g/gAB, respectively). The hydrolysates obtained under these conditions were evaluated as carbon sources for PA production, obtaining a productivity of 0.069 ± 0.006 g/L h and a yield product/substrate of 0.44 gPA/gTC. The control of pH in the culture reduced the fermentation time in the bioreactor by 52% compared with the hermetic bottles without pH control. The potential of hydrolysates as carbon sources for PA production was evidenced, as approximately 50% of the initial carbon was converted to this product. The observed yield product/substrate was similar to those reported from hydrolysates of diverse biomass types, pretreatments, or enzymatic cocktails and the same or related microorganisms. However, the system studied has advantages, such as not requiring the addition of chemical or detoxification stage, and lower temperature and time compared to other pretreatments.
{"title":"Propionic acid production by Propionibacterium acidipropionici CDBB‐B‐1981 from enzymatic hydrolysates of Agave bagasse pretreated by steam explosion","authors":"Veronica Duran‐Cruz, Sergio Hernández, I. Ortíz","doi":"10.1002/eng2.12858","DOIUrl":"https://doi.org/10.1002/eng2.12858","url":null,"abstract":"The biochemical pathway for propionic acid (PA) production is an interesting alternative that can include the utilization of biomass as feedstock. This study evaluated the utilization of Agave bagasse (AB), a lignocellulosic residue, to produce PA by Propionibacterium acidipropinici in batch systems (125 mL‐hermetic bottles and 1000 mL‐bioreactor). The process included a steam explosion pretreatment at 142°C for 15 min and enzymatic hydrolysis, where solid loading (2.75% and 5% in pretreatment and 2.5%, 3.75%, and 5% in enzymatic hydrolysis) was evaluated. Furthermore, the enzymatic concentrations of 18.3 filter paper unit (FPU)/gAB (1×) of Cellic® CTec2 and 1.5× and 3× were tested. The yields of total carbohydrates (TC) obtained at the two solid loadings tested in the pretreatment were statistically similar, but the 3x enzymatic concentration enhanced the yields of TC, glucose, and xylose (0.23 ± 0.01, 0.15 ± 0.01 and 0.03 ± 0.01 g/gAB, respectively). The hydrolysates obtained under these conditions were evaluated as carbon sources for PA production, obtaining a productivity of 0.069 ± 0.006 g/L h and a yield product/substrate of 0.44 gPA/gTC. The control of pH in the culture reduced the fermentation time in the bioreactor by 52% compared with the hermetic bottles without pH control. The potential of hydrolysates as carbon sources for PA production was evidenced, as approximately 50% of the initial carbon was converted to this product. The observed yield product/substrate was similar to those reported from hydrolysates of diverse biomass types, pretreatments, or enzymatic cocktails and the same or related microorganisms. However, the system studied has advantages, such as not requiring the addition of chemical or detoxification stage, and lower temperature and time compared to other pretreatments.","PeriodicalId":11735,"journal":{"name":"Engineering Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139781797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The frequency‐domain reflection (FDR) has been demonstrated to be a trustworthy technique in solving the defect location of power cable by field experiments. However, the location spectrum of the FDR requires manual window smoothing and can be disturbed by spurious peaks. Aiming at these shortcomings of FDR, a new method of cable defect location based on Burg power spectral (BPS) is introduced in this paper. The idea of this method is to use linear difference variance to fit the distribution of reflection coefficient spectrum and build an auto‐regressive (AR) model. The Burg algorithm is employed to estimate the coefficients model and calculate the power distribution of the AR model. Then, the cable defects will be located by BPS with high precision and resolution. In this method, the fast Fourier transform (FFT) with windowed function is replaced by an AR model without windowed function. This suppressed the impact of spurious peaks or spectrum leakage in FFT on the localization defects, and the localization resolution is higher. Finally, we validate the feasibility and effectiveness of BPS through experiments conducted on a 500 m laboratory cable and a 9.6 km submarine cable.
通过现场实验证明，频域反射（FDR）是解决电力电缆缺陷定位问题的可靠技术。然而，频域反射仪的定位频谱需要人工窗口平滑处理，而且会受到杂散峰值的干扰。针对 FDR 的这些缺点，本文介绍了一种基于伯格功率谱（BPS）的电缆缺陷定位新方法。该方法的理念是利用线性差分方差拟合反射系数频谱的分布，并建立一个自动回归（AR）模型。采用 Burg 算法估计系数模型并计算 AR 模型的功率分布。然后，通过高精度和高分辨率的 BPS 定位电缆缺陷。在这种方法中，有窗函数的快速傅立叶变换（FFT）被无窗函数的 AR 模型所取代。这就抑制了 FFT 中的杂散峰值或频谱泄漏对定位缺陷的影响，而且定位分辨率更高。最后，我们通过在 500 米实验室电缆和 9.6 千米海底电缆上进行的实验验证了 BPS 的可行性和有效性。
{"title":"A defect location method for power cable based on Burg power spectral","authors":"Zhirong Tang, Kaihua Zhou, Yun Li, P. Meng","doi":"10.1002/eng2.12859","DOIUrl":"https://doi.org/10.1002/eng2.12859","url":null,"abstract":"The frequency‐domain reflection (FDR) has been demonstrated to be a trustworthy technique in solving the defect location of power cable by field experiments. However, the location spectrum of the FDR requires manual window smoothing and can be disturbed by spurious peaks. Aiming at these shortcomings of FDR, a new method of cable defect location based on Burg power spectral (BPS) is introduced in this paper. The idea of this method is to use linear difference variance to fit the distribution of reflection coefficient spectrum and build an auto‐regressive (AR) model. The Burg algorithm is employed to estimate the coefficients model and calculate the power distribution of the AR model. Then, the cable defects will be located by BPS with high precision and resolution. In this method, the fast Fourier transform (FFT) with windowed function is replaced by an AR model without windowed function. This suppressed the impact of spurious peaks or spectrum leakage in FFT on the localization defects, and the localization resolution is higher. Finally, we validate the feasibility and effectiveness of BPS through experiments conducted on a 500 m laboratory cable and a 9.6 km submarine cable.","PeriodicalId":11735,"journal":{"name":"Engineering Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139853716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：