Pub Date : 2022-07-03DOI: 10.1080/19475411.2022.2107110
Mohammad Aghvami‐Panah, Ao Wang, Mahyar Panahi-Sarmad, Seyed Hossein Seyed Esfahani, A. Seraji, Mehrnaz Shahbazi, R. Ghaffarian, Seifollah Jamalpour, Xue Xiao
ABSTRACT The effect of carbon black (CB), carbon nanotube (CNT), and graphene (G) on foaming, electrical conductivity (EC), and electromagnetic interference (EMI) shielding of polystyrene (PS) foam that has been produced via microwave heating operation and supercritical carbon dioxide (CO2) was studied. Foams containing 1 wt %, CNT, and G reached over 90% porosity after 30 s and 3 min radiation time, respectively; however, PS/CB foam did not expand properly even after 3.5 min. In addition, the expansion ratio of PS/CB and PS/G was one-sixth and one-half of PS/CNT, respectively – due to the great CNT’s ability to convert microwave radiation to heat. EC of solid and porous nanocomposites has been increased via raising filler content; however, PS/CNT displayed the highest value at the same volume fractions. This ascending trend could not endure during foaming, so a remarkable optimum-point has been observed for nanocomposite foams. Eventually, EMI-shielding properties of solid and foam nanocomposites were discussed. Graphical Abstract
研究了炭黑(CB)、碳纳米管(CNT)和石墨烯(G)对微波加热和超临界二氧化碳(CO2)制备的聚苯乙烯(PS)泡沫的发泡、电导率(EC)和电磁干扰(EMI)屏蔽的影响。含碳纳米管1 wt %、碳纳米管1 wt %、碳纳米管1 G %的泡沫在辐照30 s和3 min后孔隙率达到90%以上;然而，即使在3.5分钟后，PS/CB泡沫也没有正常膨胀。此外，PS/CB和PS/G的膨胀率分别是PS/CNT的六分之一和二分之一，这是由于CNT具有将微波辐射转化为热量的强大能力。提高填料含量可提高固体和多孔纳米复合材料的电导率;而在相同体积分数下，PS/CNT的值最高。这种上升趋势在发泡过程中不能持续，因此纳米复合材料泡沫有一个显著的最佳点。最后讨论了固体纳米复合材料和泡沫纳米复合材料的电磁屏蔽性能。图形抽象
{"title":"A comparison study on polymeric nanocomposite foams with various carbon nanoparticles: adjusting radiation time and effect on electrical behavior and microcellular structure","authors":"Mohammad Aghvami‐Panah, Ao Wang, Mahyar Panahi-Sarmad, Seyed Hossein Seyed Esfahani, A. Seraji, Mehrnaz Shahbazi, R. Ghaffarian, Seifollah Jamalpour, Xue Xiao","doi":"10.1080/19475411.2022.2107110","DOIUrl":"https://doi.org/10.1080/19475411.2022.2107110","url":null,"abstract":"ABSTRACT The effect of carbon black (CB), carbon nanotube (CNT), and graphene (G) on foaming, electrical conductivity (EC), and electromagnetic interference (EMI) shielding of polystyrene (PS) foam that has been produced via microwave heating operation and supercritical carbon dioxide (CO2) was studied. Foams containing 1 wt %, CNT, and G reached over 90% porosity after 30 s and 3 min radiation time, respectively; however, PS/CB foam did not expand properly even after 3.5 min. In addition, the expansion ratio of PS/CB and PS/G was one-sixth and one-half of PS/CNT, respectively – due to the great CNT’s ability to convert microwave radiation to heat. EC of solid and porous nanocomposites has been increased via raising filler content; however, PS/CNT displayed the highest value at the same volume fractions. This ascending trend could not endure during foaming, so a remarkable optimum-point has been observed for nanocomposite foams. Eventually, EMI-shielding properties of solid and foam nanocomposites were discussed. Graphical Abstract","PeriodicalId":48516,"journal":{"name":"International Journal of Smart and Nano Materials","volume":"13 1","pages":"504 - 528"},"PeriodicalIF":3.9,"publicationDate":"2022-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43493453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-03DOI: 10.1080/19475411.2022.2103598
Chen Zhang, Renhao Liu, C. Tao, C. Zhang, H. Ji, J. Qiu
ABSTRACT In this work, a novel aircraft door sealing structure driven by shape memory alloys (SMAs) is proposed that offers much improved sealing capability than traditional sealing plates. The two-way shape memory effect (TWSME) of SMAs is utilized so that the proposed sealing plate can change its shape through heating and cooling of the driving SMA unit. Considering the inhomogeneous temperature and recovery strain field the SMA exhibits while being trained, a modified finite element (FE) model of the sealing structure is established to predict the deflection of the SMA-based sealing plate. Finally, verification experiments are carried out. The experimental results show good agreement with the FE predictions, indicating good accuracy of the modified FE model as well as the effectiveness of the proposed sealing structure. GRAPHICAL ABSTRACT
{"title":"Design, construction, and modeling of aircraft door sealing plate based on SMAs","authors":"Chen Zhang, Renhao Liu, C. Tao, C. Zhang, H. Ji, J. Qiu","doi":"10.1080/19475411.2022.2103598","DOIUrl":"https://doi.org/10.1080/19475411.2022.2103598","url":null,"abstract":"ABSTRACT In this work, a novel aircraft door sealing structure driven by shape memory alloys (SMAs) is proposed that offers much improved sealing capability than traditional sealing plates. The two-way shape memory effect (TWSME) of SMAs is utilized so that the proposed sealing plate can change its shape through heating and cooling of the driving SMA unit. Considering the inhomogeneous temperature and recovery strain field the SMA exhibits while being trained, a modified finite element (FE) model of the sealing structure is established to predict the deflection of the SMA-based sealing plate. Finally, verification experiments are carried out. The experimental results show good agreement with the FE predictions, indicating good accuracy of the modified FE model as well as the effectiveness of the proposed sealing structure. GRAPHICAL ABSTRACT","PeriodicalId":48516,"journal":{"name":"International Journal of Smart and Nano Materials","volume":"13 1","pages":"481 - 503"},"PeriodicalIF":3.9,"publicationDate":"2022-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49084309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-30Print Date: 2022-07-01DOI: 10.3399/BJGP.2021.0691
Enric Aragonès, Isabel Del Cura-González, Lucía Hernández-Rivas, Elena Polentinos-Castro, Maria Isabel Fernández-San-Martín, Juan A López-Rodríguez, Josep M Molina-Aragonés, Franco Amigo, Itxaso Alayo, Philippe Mortier, Montse Ferrer, Víctor Pérez-Solà, Gemma Vilagut, Jordi Alonso
Background: The COVID-19 pandemic has had a major impact on the mental health of healthcare workers, yet studies in primary care workers are scarce.
Aim: To investigate the prevalence of and associated factors for psychological distress in primary care workers during the first COVID-19 outbreak.
Design and setting: This was a multicentre, cross-sectional, web-based survey conducted in primary healthcare workers in Spain, between May and September 2020.
Method: Healthcare workers were invited to complete a survey to evaluate sociodemographic and work-related characteristics, COVID-19 infection status, exposure to patients with COVID-19, and resilience (using the Connor-Davidson Resilience Scale), in addition to being screened for common mental disorders (depression, anxiety disorders, post-traumatic stress disorder, panic attacks, and substance use disorder). Positive screening for any of these disorders was analysed globally using the term 'any current mental disorder'.
Results: A total of 2928 primary care professionals participated in the survey. Of them, 43.7% (95% confidence interval [CI] = 41.9 to 45.4) tested positive for a current mental disorder. Female sex (odds ratio [OR] 1.61, 95% CI = 1.25 to 2.06), having previous mental disorders (OR 2.58, 95% CI = 2.15 to 3.10), greater occupational exposure to patients with COVID-19 (OR 2.63, 95% CI = 1.98 to 3.51), having children or dependents (OR 1.35, 95% CI = 1.04 to 1.76 and OR 1.59, 95% CI = 1.20 to 2.11, respectively), or having an administrative job (OR 2.24, 95% CI = 1.66 to 3.03) were associated with a higher risk of any current mental disorder. Personal resilience was shown to be a protective factor.
Conclusion: Almost half of primary care workers showed significant psychological distress. Strategies to support the mental health of primary care workers are necessary, including designing psychological support and resilience-building interventions based on risk factors identified.
背景：COVID-19大流行对医护人员的心理健康产生了重大影响，但针对基层医护人员的研究却很少。目的：调查COVID-19首次爆发期间基层医护人员心理困扰的发生率及其相关因素：这是一项多中心、横断面、基于网络的调查，于 2020 年 5 月至 9 月间在西班牙的基层医疗工作者中进行：医护人员受邀完成一项调查，以评估其社会人口学特征和工作相关特征、COVID-19 感染状况、与 COVID-19 患者的接触情况和抗病能力（使用 Connor-Davidson 抗病能力量表），此外还对其进行了常见精神障碍（抑郁症、焦虑症、创伤后应激障碍、恐慌症和药物使用障碍）筛查。对这些疾病的阳性筛查结果使用 "任何当前精神障碍 "一词进行全面分析：共有 2928 名初级保健专业人员参与了调查。其中，43.7%（95% 置信区间 [CI] = 41.9 至 45.4）的人对当前精神障碍检测呈阳性。女性（几率比[OR] 1.61，95% CI = 1.25 至 2.06）、曾有精神障碍（OR 2.58，95% CI = 2.15 至 3.10）、与 COVID-19 患者有更多的职业接触（OR 2.63，95% CI = 1.98 至 3.51）、有子女或受抚养人（OR 2.63，95% CI = 1.98 至 3.51）。51）、有子女或受抚养人（OR 1.35，95% CI = 1.04 至 1.76 和 OR 1.59，95% CI = 1.20 至 2.11）或从事行政工作（OR 2.24，95% CI = 1.66 至 3.03）与当前任何精神障碍的较高风险相关。个人复原力是一个保护性因素：结论：近一半的初级保健工作者表现出严重的心理困扰。有必要制定支持基层医疗工作者心理健康的策略，包括根据已确定的风险因素设计心理支持和复原力建设干预措施。
{"title":"Psychological impact of the COVID-19 pandemic on primary care workers: a cross-sectional study.","authors":"Enric Aragonès, Isabel Del Cura-González, Lucía Hernández-Rivas, Elena Polentinos-Castro, Maria Isabel Fernández-San-Martín, Juan A López-Rodríguez, Josep M Molina-Aragonés, Franco Amigo, Itxaso Alayo, Philippe Mortier, Montse Ferrer, Víctor Pérez-Solà, Gemma Vilagut, Jordi Alonso","doi":"10.3399/BJGP.2021.0691","DOIUrl":"10.3399/BJGP.2021.0691","url":null,"abstract":"<p><strong>Background: </strong>The COVID-19 pandemic has had a major impact on the mental health of healthcare workers, yet studies in primary care workers are scarce.</p><p><strong>Aim: </strong>To investigate the prevalence of and associated factors for psychological distress in primary care workers during the first COVID-19 outbreak.</p><p><strong>Design and setting: </strong>This was a multicentre, cross-sectional, web-based survey conducted in primary healthcare workers in Spain, between May and September 2020.</p><p><strong>Method: </strong>Healthcare workers were invited to complete a survey to evaluate sociodemographic and work-related characteristics, COVID-19 infection status, exposure to patients with COVID-19, and resilience (using the Connor-Davidson Resilience Scale), in addition to being screened for common mental disorders (depression, anxiety disorders, post-traumatic stress disorder, panic attacks, and substance use disorder). Positive screening for any of these disorders was analysed globally using the term 'any current mental disorder'.</p><p><strong>Results: </strong>A total of 2928 primary care professionals participated in the survey. Of them, 43.7% (95% confidence interval [CI] = 41.9 to 45.4) tested positive for a current mental disorder. Female sex (odds ratio [OR] 1.61, 95% CI = 1.25 to 2.06), having previous mental disorders (OR 2.58, 95% CI = 2.15 to 3.10), greater occupational exposure to patients with COVID-19 (OR 2.63, 95% CI = 1.98 to 3.51), having children or dependents (OR 1.35, 95% CI = 1.04 to 1.76 and OR 1.59, 95% CI = 1.20 to 2.11, respectively), or having an administrative job (OR 2.24, 95% CI = 1.66 to 3.03) were associated with a higher risk of any current mental disorder. Personal resilience was shown to be a protective factor.</p><p><strong>Conclusion: </strong>Almost half of primary care workers showed significant psychological distress. Strategies to support the mental health of primary care workers are necessary, including designing psychological support and resilience-building interventions based on risk factors identified.</p>","PeriodicalId":48516,"journal":{"name":"International Journal of Smart and Nano Materials","volume":"12 1","pages":"e501-e510"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9037185/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78482608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-28DOI: 10.1080/19475411.2022.2091058
Zinan Zhao, Jun Zhu, Wei-qiu Chen
ABSTRACT With the development and applications of nano-electro-mechanical systems, academic interest in the mechanical behavior of piezoelectric structures at nanoscale is increasing. Interesting unconventional phenomena have been observed either experimentally or through molecular dynamics simulation. The most common and also important one is the size-dependent characteristics. Classical continuum mechanics with necessary modifications has been proven to be very powerful in explaining these particular characteristics in a relatively simple theoretical framework. This article reviews the recent advances in understanding the size-dependent dynamic responses of piezoelectric nanostructures from the viewpoint of modified continuum mechanics. Particular attentions are paid to three advanced theories of piezoelectricity (e.g. gradient piezoelectricity, surface piezoelectricity, and nonlocal piezoelectricity) and their abilities to predict unconventional vibration and wave characteristics in piezoelectric structures and devices at the nanoscale. The article could serve as a useful reference for the future research on or design of nanostructures with multifield couplings. Graphical Abstract
{"title":"Size-dependent vibrations and waves in piezoelectric nanostructures: a literature review","authors":"Zinan Zhao, Jun Zhu, Wei-qiu Chen","doi":"10.1080/19475411.2022.2091058","DOIUrl":"https://doi.org/10.1080/19475411.2022.2091058","url":null,"abstract":"ABSTRACT With the development and applications of nano-electro-mechanical systems, academic interest in the mechanical behavior of piezoelectric structures at nanoscale is increasing. Interesting unconventional phenomena have been observed either experimentally or through molecular dynamics simulation. The most common and also important one is the size-dependent characteristics. Classical continuum mechanics with necessary modifications has been proven to be very powerful in explaining these particular characteristics in a relatively simple theoretical framework. This article reviews the recent advances in understanding the size-dependent dynamic responses of piezoelectric nanostructures from the viewpoint of modified continuum mechanics. Particular attentions are paid to three advanced theories of piezoelectricity (e.g. gradient piezoelectricity, surface piezoelectricity, and nonlocal piezoelectricity) and their abilities to predict unconventional vibration and wave characteristics in piezoelectric structures and devices at the nanoscale. The article could serve as a useful reference for the future research on or design of nanostructures with multifield couplings. Graphical Abstract","PeriodicalId":48516,"journal":{"name":"International Journal of Smart and Nano Materials","volume":"13 1","pages":"391 - 431"},"PeriodicalIF":3.9,"publicationDate":"2022-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48424612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-21DOI: 10.1080/19475411.2022.2091059
Tao Yan, Yuting Wu, Jian Tang, Z. Pan
ABSTRACT Carbon nanofibers (CNFs) with excellent conductivity and stability have become a promising material to design the strain sensing network. To date, however, the effect of the stacked structure of CNF membrane on the sensing performance has rarely been studied. In this work, we reported a high-performance sensor based on the cross-stacked aligned CNF membrane. The effects of cross-stacked structures on the sensing characteristics were systematically investigated. The flexible strain sensor could capture low detection limit (<0.1%) with a gauge factor (GF) of 4.24 and wide strain range up to 130%. The uniform GF value reached 2050 when the strain was in the range of 100–130%. In addition, the high linearity under 40% strain (>0.998), excellent durability and quick response time (<200 ms) were demonstrated. The excellent comprehensive performances were simultaneously obtained. The sensor could be used in extensive applications, such as monitoring body movements and distinguishing the track of writing. Graphical abstract
{"title":"Flexible strain sensors fabricated using aligned carbon nanofiber membranes with cross-stacked structure for extensive applications","authors":"Tao Yan, Yuting Wu, Jian Tang, Z. Pan","doi":"10.1080/19475411.2022.2091059","DOIUrl":"https://doi.org/10.1080/19475411.2022.2091059","url":null,"abstract":"ABSTRACT Carbon nanofibers (CNFs) with excellent conductivity and stability have become a promising material to design the strain sensing network. To date, however, the effect of the stacked structure of CNF membrane on the sensing performance has rarely been studied. In this work, we reported a high-performance sensor based on the cross-stacked aligned CNF membrane. The effects of cross-stacked structures on the sensing characteristics were systematically investigated. The flexible strain sensor could capture low detection limit (<0.1%) with a gauge factor (GF) of 4.24 and wide strain range up to 130%. The uniform GF value reached 2050 when the strain was in the range of 100–130%. In addition, the high linearity under 40% strain (>0.998), excellent durability and quick response time (<200 ms) were demonstrated. The excellent comprehensive performances were simultaneously obtained. The sensor could be used in extensive applications, such as monitoring body movements and distinguishing the track of writing. Graphical abstract","PeriodicalId":48516,"journal":{"name":"International Journal of Smart and Nano Materials","volume":"13 1","pages":"432 - 446"},"PeriodicalIF":3.9,"publicationDate":"2022-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42995964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT Vitrimer is a new type of material that combine the advantages of thermoplastic and thermoset materials. The rapid dynamic exchange reactions at high temperature allow the topology of cross-linked networks to change and rearrange while keeping material structures and properties intact. The concept of vitrimer has emerged to provide a viable strategy for the recycling of high-performance polymer materials, and lots of research works have been carried out for the development of various types of vitrimers. In addition, the recycling strategies for vitrimers are particularly important to determine the performance and potential applications of the recovered materials. Therefore, it is an innovative and valuable perspective to discuss vitrimer materials according to their different recycling strategies. In this review, we start with a brief overview of vitrimers, and then, focus on recycling strategies for vitrimers. Specifically, we highlight the advantages and disadvantages of the two different recycling strategies: physical and chemical recycling methods, and then explore the feasibility of upcycling vitrimers using 3D printing technology. Finally, the impact of recycling strategies on vitrimer materials and the prospects for maximizing the use of vitrimer materials are discussed. Graphical abstract
{"title":"Recycling strategies for vitrimers","authors":"Haochuan Zhang, Jingjing Cui, Guang Hu, Biao Zhang","doi":"10.1080/19475411.2022.2087785","DOIUrl":"https://doi.org/10.1080/19475411.2022.2087785","url":null,"abstract":"ABSTRACT Vitrimer is a new type of material that combine the advantages of thermoplastic and thermoset materials. The rapid dynamic exchange reactions at high temperature allow the topology of cross-linked networks to change and rearrange while keeping material structures and properties intact. The concept of vitrimer has emerged to provide a viable strategy for the recycling of high-performance polymer materials, and lots of research works have been carried out for the development of various types of vitrimers. In addition, the recycling strategies for vitrimers are particularly important to determine the performance and potential applications of the recovered materials. Therefore, it is an innovative and valuable perspective to discuss vitrimer materials according to their different recycling strategies. In this review, we start with a brief overview of vitrimers, and then, focus on recycling strategies for vitrimers. Specifically, we highlight the advantages and disadvantages of the two different recycling strategies: physical and chemical recycling methods, and then explore the feasibility of upcycling vitrimers using 3D printing technology. Finally, the impact of recycling strategies on vitrimer materials and the prospects for maximizing the use of vitrimer materials are discussed. Graphical abstract","PeriodicalId":48516,"journal":{"name":"International Journal of Smart and Nano Materials","volume":"13 1","pages":"367 - 390"},"PeriodicalIF":3.9,"publicationDate":"2022-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46036976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-03DOI: 10.1080/19475411.2022.2084173
Yingzhi Wang, Jie Deng, Shijing Zhang, He Li, Weishan Chen, Yingxiang Liu
ABSTRACT Multi-motor configuration of multi-DOF (degree of freedom) optical system is a major source of redundant structure, putting a limitation on the simple and miniaturized design. Thus, a novel two-DOF ultrasonic motor (USM) is proposed to provide a feasible method of application in the lens autofocus of the optical system. The proposed USM operates by one longitudinal mode and two orthogonal bending modes, which is inspired by the bionic motion principle of the earthworms. The frequency degeneration among the three working modes is performed, and the working principle of the USM is verified via the FEM simulation. A prototype of the two-DOF USM is fabricated, and its mechanical output characteristics are tested. The experimental results indicate that the prototype achieves the maximum rotary and linear speeds of 3319.6 rpm and 57.6 mm/s, respectively. Furthermore, we demonstrate the result of a simple focusing experiment using the prototype and obtain a series of clear pictures, which verifies the feasibility of application in the optical focusing system. Graphical Abstract
{"title":"Design of a linear-rotary ultrasonic motor for optical focusing inspired by the bionic motion principles of the earthworms","authors":"Yingzhi Wang, Jie Deng, Shijing Zhang, He Li, Weishan Chen, Yingxiang Liu","doi":"10.1080/19475411.2022.2084173","DOIUrl":"https://doi.org/10.1080/19475411.2022.2084173","url":null,"abstract":"ABSTRACT Multi-motor configuration of multi-DOF (degree of freedom) optical system is a major source of redundant structure, putting a limitation on the simple and miniaturized design. Thus, a novel two-DOF ultrasonic motor (USM) is proposed to provide a feasible method of application in the lens autofocus of the optical system. The proposed USM operates by one longitudinal mode and two orthogonal bending modes, which is inspired by the bionic motion principle of the earthworms. The frequency degeneration among the three working modes is performed, and the working principle of the USM is verified via the FEM simulation. A prototype of the two-DOF USM is fabricated, and its mechanical output characteristics are tested. The experimental results indicate that the prototype achieves the maximum rotary and linear speeds of 3319.6 rpm and 57.6 mm/s, respectively. Furthermore, we demonstrate the result of a simple focusing experiment using the prototype and obtain a series of clear pictures, which verifies the feasibility of application in the optical focusing system. Graphical Abstract","PeriodicalId":48516,"journal":{"name":"International Journal of Smart and Nano Materials","volume":"13 1","pages":"346 - 365"},"PeriodicalIF":3.9,"publicationDate":"2022-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46410078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-03DOI: 10.1080/19475411.2022.2076754
Yang Yang, Yongquan Wang, Tao Yao, Xiaojuan Feng
ABSTRACT Leveraging advances in shape memory alloys (SMAs) and flexible thermoelectric devices (f-TEDs), this paper presents a structural and functional integrity composite sheet to address the inefficient and bulky activation of 2-D SMAs. A series of experimental tests were performed to reveal the generation, change, and transfer mechanisms of different types of electrically-induced heat in the f-TED, as well as the temperature-induced SMA phase transformation behaviors. The results show that the composite sheet exhibited good bidirectional thermal management capacity. The austenite deformation can be completed within 10s at an operating current of 2 A. The cooling recovery, in particular, performs much better than in conventional modes (the temperature declines exponentially with time). Finally, through two functional prototypes, a light switch and a flexible gripper, the application potential of the proposed composite was further experimentally demonstrated. Graphical Abstract
{"title":"A flexible and smart shape memory alloy composite sheet based on efficient and bidirectional thermal management","authors":"Yang Yang, Yongquan Wang, Tao Yao, Xiaojuan Feng","doi":"10.1080/19475411.2022.2076754","DOIUrl":"https://doi.org/10.1080/19475411.2022.2076754","url":null,"abstract":"ABSTRACT Leveraging advances in shape memory alloys (SMAs) and flexible thermoelectric devices (f-TEDs), this paper presents a structural and functional integrity composite sheet to address the inefficient and bulky activation of 2-D SMAs. A series of experimental tests were performed to reveal the generation, change, and transfer mechanisms of different types of electrically-induced heat in the f-TED, as well as the temperature-induced SMA phase transformation behaviors. The results show that the composite sheet exhibited good bidirectional thermal management capacity. The austenite deformation can be completed within 10s at an operating current of 2 A. The cooling recovery, in particular, performs much better than in conventional modes (the temperature declines exponentially with time). Finally, through two functional prototypes, a light switch and a flexible gripper, the application potential of the proposed composite was further experimentally demonstrated. Graphical Abstract","PeriodicalId":48516,"journal":{"name":"International Journal of Smart and Nano Materials","volume":"13 1","pages":"315 - 329"},"PeriodicalIF":3.9,"publicationDate":"2022-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46507931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-03DOI: 10.1080/19475411.2022.2069875
Cheng Shen, Yifan Kong, T. J. Lu, Shasha Yang
ABSTRACT Although forbidden band effect in perfectly periodic phononic crystals (PC) is very attractive, random disordered (i.e. detuning) phenomenon is inevitable in engineering processing, thus exploring the effect of detuning on the wave characteristics of PC becomes a necessity. In this study, fundamental governing equations and boundary conditions are derived from the principle of virtual work. Wave characteristics and localization factor of one-dimensional (1D) detuned nano-PC are investigated based on the transfer matrix method, with flexoelectric effect duly accounted for. Subsequently, with nano-PC taken for illustration, forbidden band properties and localization factor of 1D elastic waves in harmonic and detuned states are systematically characterized. It is demonstrated that localization factor can characterize the energy band structure of 1D PC perfectly. Flexoelectric effect tends to widen the width of forbidden band with increasing detuning, and detuning is linearly related to the bandwidth. The forbidden band is more sensitive to flexoelectric coefficient detuning than thickness detuning. The research results provide useful theoretical guidance for designing high-frequency nanoscaled devices with the function of filtering based on band gap effect of nano-PC. Graphical abstract
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ABSTRACT Composite materials have been widely used in many industries due to their excellent mechanical properties. It is difficult to analyze the integrity and durability of composite structures because of their own characteristics and the complexity of load and environments. Structural health monitoring (SHM) based on built-in sensor networks has been widely evaluated as a method to improve the safety and reliability of composite structures and reduce the operational cost. With the rapid development of machine learning, a large number of machine learning algorithms have been applied in many disciplines, and also are being applied in the field of SHM to avoid the limitations resulting from the need of physical models. In this paper, the damage monitoring technologies often used for composite structures are briefly outlined, and the applications of machine learning in damage monitoring of composite structures are concisely reviewed. Then, challenges and solutions for quantitative damage monitoring of composite structures based on machine learning are discussed, focusing on the complete acquisition of monitoring data, deep analysis of the correlation between sensor signal eigenvalues and composite structure states, and quantitative intelligent identification of composite delamination damage. Finally, the development trend of machine learning-based SHM for composite structures is discussed.
{"title":"Machine Learning Based Quantitative Damage Monitoring of Composite Structure","authors":"X. Qing, Yunlai Liao, Yihan Wang, Binqiang Chen, Fanghong Zhang, Yishou Wang","doi":"10.1080/19475411.2022.2054878","DOIUrl":"https://doi.org/10.1080/19475411.2022.2054878","url":null,"abstract":"ABSTRACT Composite materials have been widely used in many industries due to their excellent mechanical properties. It is difficult to analyze the integrity and durability of composite structures because of their own characteristics and the complexity of load and environments. Structural health monitoring (SHM) based on built-in sensor networks has been widely evaluated as a method to improve the safety and reliability of composite structures and reduce the operational cost. With the rapid development of machine learning, a large number of machine learning algorithms have been applied in many disciplines, and also are being applied in the field of SHM to avoid the limitations resulting from the need of physical models. In this paper, the damage monitoring technologies often used for composite structures are briefly outlined, and the applications of machine learning in damage monitoring of composite structures are concisely reviewed. Then, challenges and solutions for quantitative damage monitoring of composite structures based on machine learning are discussed, focusing on the complete acquisition of monitoring data, deep analysis of the correlation between sensor signal eigenvalues and composite structure states, and quantitative intelligent identification of composite delamination damage. Finally, the development trend of machine learning-based SHM for composite structures is discussed.","PeriodicalId":48516,"journal":{"name":"International Journal of Smart and Nano Materials","volume":"13 1","pages":"167 - 202"},"PeriodicalIF":3.9,"publicationDate":"2022-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44584561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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