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Design and applications of morphing aircraft and their structures

《机械工程前沿（英文）》 2023年第18卷第3期 doi: 10.1007/s11465-023-0750-6

摘要： Morphing aircraft can adaptively regulate their aerodynamic layout to meet the demands of varying flight conditions, improve their aerodynamic efficiency, and reduce their energy consumption. The design and fabrication of high-performance, lightweight, and intelligent morphing structures have become a hot topic in advanced aircraft design. This paper discusses morphing aircraft development history, structural characteristics, existing applications, and future prospects. First, some conventional mechanical morphing aircraft are examined with focus on their morphing modes, mechanisms, advantages, and disadvantages. Second, the novel applications of several technologies for morphing unmanned aerial vehicles, including additive manufacturing for fabricating complex morphing structures, lattice technology for reducing structural weight, and multi-mode morphing combined with flexible skins and foldable structures, are summarized and categorized. Moreover, in consideration of the further development of active morphing aircraft, the paper reviews morphing structures driven by smart material actuators, such as shape memory alloy and macro-fiber composites, and analyzes their advantages and limitations. Third, the paper discusses multiple challenges, including flexible structures, flexible skins, and control systems, in the design of future morphing aircraft. Lastly, the development and application of morphing structures in the aerospace field are discussed to provide a reference for future research and engineering applications.

关键词： morphing aircraft additive manufacturing lattice structure smart material flexible structure flexible skin

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Deformation analysis of shape memory polymer for morphing wing skin under airflow

Weilong YIN, Jingcang LIU, Jinsong LENG,

《机械工程前沿（英文）》 2009年第4卷第4期页码 447-449 doi: 10.1007/s11465-009-0062-5

摘要： The method for analyzing the out-of-plane deformation of a flexible skin under airflow is developed in this paper. The aerodynamic analysis is performed using the CFD software, and the structural analysis is performed using finite element method. The chief aim of the present study is to investigate the out-of-plane deformation of the shape memory polymer (SMP) skin at different temperatures. Numerical results show that the maximum out-of-plane displacement of the SMP skin increases with increasing temperature. When the SMP skin is heated to 53°C, the maximum out-of-plane displacement is about 7 mm. It decreases by 72%, when the SMP skin is applied with a uniform pre-strain of 0.1.

关键词： aircraft morphing skin shape memory polymer (SMP) deformation pre-strain

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The critical importance of epigenetics in autoimmune-related skin diseases

《医学前沿（英文）》 2023年第17卷第1期页码 43-57 doi: 10.1007/s11684-022-0980-8

摘要： Autoimmune-related skin diseases are a group of disorders with diverse etiology and pathophysiology involved in autoimmunity. Genetics and environmental factors may contribute to the development of these autoimmune disorders. Although the etiology and pathogenesis of these disorders are poorly understood, environmental variables that induce aberrant epigenetic regulations may provide some insights. Epigenetics is the study of heritable mechanisms that regulate gene expression without changing DNA sequences. The most important epigenetic mechanisms are DNA methylation, histone modification, and noncoding RNAs. In this review, we discuss the most recent findings regarding the function of epigenetic mechanisms in autoimmune-related skin disorders, including systemic lupus erythematosus, bullous skin diseases, psoriasis, and systemic sclerosis. These findings will expand our understanding and highlight the possible clinical applications of precision epigenetics approaches.

关键词： epigenetics autoimmune-related skin diseases DNA methylation histone modifications noncoding RNAs

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Hyperthermia on skin immune system and its application in the treatment of human papillomavirus-infectedskin diseases

null

《医学前沿（英文）》 2014年第8卷第1期页码 1-5 doi: 10.1007/s11684-014-0309-3

摘要：

Hyperthermia is a condition characterized by increased body temperature as a consequence of failed thermoregulation. Hyperthermia occurs when a body produces or absorbs more heat than it dissipates. Hyperthermia also elicits various effects on the physiology of living cells. For instance, fever-range temperature (39β°C to 40β°C) can modulate the activities of immune cells, including antigen-presenting cells, T cells, and natural killer cells. Heat shock temperature (41β°C to 43β°C) can increase the immunogenicity of tumor cells. Cytotoxic temperature (>43β°C) can create an antigen source to induce an anti-tumor immune response. The immunomodulatory effect of hyperthermia has promoted an interest in hyperthermia-aided immunotherapy, particularly against tumors. Hyperthermia has also been used to treat deep fungal, bacterial, and viral skin infections. We conducted a series of open or controlled trials to treat skin human papillomavirus infection by inducing local hyperthermia. More than half of the patients were significantly cured compared with those in the control trial. A series of challenging clinical cases, such as large lesions in pregnant patients or patients with diabetes mellitus, were also successfully and safely managed using the proposed method. However, further studies should be conducted to clarify the underlying mechanisms and promote the clinical applications of hyperthermia.

关键词： hyperthermia HPV immune response virus tumor

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Risk stratification system for skin and soft tissue infections after allogeneic hematopoietic stem cell

《医学前沿（英文）》 2022年第16卷第6期页码 957-968 doi: 10.1007/s11684-021-0910-1

摘要： Skin and soft tissue infections (SSTIs) refer to infections involving the skin, subcutaneous tissue, fascia, and muscle. In transplant populations with hematological malignancies, an immunocompromised status and the routine use of immunosuppressants increase the risk of SSTIs greatly. However, to date, the profiles and clinical outcomes of SSTIs in hematopoietic stem cell transplantation (HSCT) patients remain unclear. This study included 228 patients (3.67%) who developed SSTIs within 180 days after allogeneic HSCT from January 2004 to December 2019 in Peking University People’s Hospital. The overall annual survival rate was 71.5%. We compared the differences between survivors and non-survivors a year after transplant and found that primary platelet graft failure (PPGF), comorbidities of acute kidney injury (AKI), and hospital-acquired pneumonia (HAP) were independent risk factors for death in the study population. A PPGF–AKI–HAP risk stratification system was established with a mortality risk score of 1×PPGF+1×AKI+1×HAP. The areas under the curves of internal and external validation were 0.833 (95% CI 0.760–0.906) and 0.826 (95% CI 0.715–0.937), respectively. The calibration plot revealed the high consistency of the estimated risks, and decision curve analysis showed considerable net benefits for patients.

关键词： skin and soft tissue infections hematopoietic stem cell transplantation risk stratification system mortality

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Numerical study of thermal characteristics of double skin facade system with middle shade

Shaoning LIU, Xiangfei KONG, Hua YANG, Minchao FAN, Xin ZHAN

《能源前沿（英文）》 2021年第15卷第1期页码 222-234 doi: 10.1007/s11708-017-0480-8

摘要： Architectural shade is an effective method for improving building energy efficiency. A new shade combined with the double skin façade (DSF) system, called middle shade (MS), was introduced and developed for buildings. In this paper, a 3D dynamic simulation was conducted to analyze the influence of MS combined with DSF on the indoor thermal characteristics. The research on MS for DSF involves the temperature, the ventilation rate, the velocity distribution of the air flow duct, and the indoor temperature. The results show that the angle and position of the shade in the three seasons are different, and different conditions effectively enhance the indoor thermal characteristics. In summer, the appearance of MS in DSF makes the indoor temperature significantly lower. The indoor temperature is obviously lower than that of the air flow duct, and the temperature of the air flow duct is less affected by MS. The influence of the position of blinds on indoor temperature and ventilation rate is greater than the influence of the angle of blinds. According to the climate characteristics of winter and transition season, in winter, early spring, and late autumn, the indoor temperature decreases with the increase of the position of blinds at daytime, but the opposite is true at night. The results found in this paper can provide reference for the design and use of MS combined with DSF in hot summer and cold winter zone.

关键词： middle shade position thermal characteristics double skin facade

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Moment-curvature relationship of FRP-concrete-steel double-skin tubular members

Mingxue LIU, Jiaru QIAN

《结构与土木工程前沿（英文）》 2009年第3卷第1期页码 25-31 doi: 10.1007/s11709-009-0012-7

摘要： Tests were conducted on 3 specimens to study the flexural behavior of fiber reinforced polymer (FRP)-concrete-steel double-skin tubular members (DSTMs). The strip method was used to calculate the section moment-curvature curves of the 3 specimens and 12 models. A theoretical formula is presented for the flexural strength of DSTMs. The test results show that the tension zone of the specimen FRP tubes was in hoop compression while the compression zone was in hoop tension. The load-carrying capacity did not decrease even when the mid-span deflection reached about 1/24 of the span length. The tests, simulation and theoretical analysis resulted in a simplified formula for the flexural strength of DSTMs and a tri-linear moment-curvature model was expressed as a function of the section bending stiffness for DSTMs.

关键词： fiber reinforced polymer (FRP) concrete steel double-skin tubular members (DSTMs) moment-curvature curve flexural strength

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Piezoelectric pump with flexible venous valves for active cell transmission

《机械工程前沿（英文）》 2022年第17卷第4期 doi: 10.1007/s11465-022-0712-4

摘要： The development of organ-on-a-chip systems demands high requirements for adequate micro-pump performance, which needs excellent performance and effective transport of active cells. In this study, we designed a piezoelectric pump with a flexible venous valve inspired by that of humans. Performance test of the proposed pump with deionized water as the transmission medium shows a maximum output flow rate of 14.95 mL/min when the input voltage is 100 V, and the pump can transfer aqueous solutions of glycerol with a viscosity of 10.8 mPa·s. Cell survival rate can reach 97.22% with a yeast cell culture solution as the transmission medium. A computational model of the electric-solid-liquid multi-physical field coupling of the piezoelectric pump with a flexible venous valve is established, and simulation results are consistent with experimental results. The proposed pump can help to construct the circulating organ-on-a-chip system, and the simple structure and portable application can enrich the design of microfluidic systems. In addition, the multi-physical field coupling computational model established for the proposed piezoelectric pump can provide an in-depth study of the characteristics of the flow field, facilitating the optimal design of the micro-pump and providing a reference for the further study of active cell transport in organ-on-a-chip systems.

关键词： venous valve flexible venous valve cell transmission organ-on-a-chip system piezoelectric device

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Analysis of effect of different construction methods of piles on the end effect on skin friction of piles

ZHOU Hongbo, CHEN Zhuchang

《结构与土木工程前沿（英文）》 2007年第1卷第4期页码 458-463 doi: 10.1007/s11709-007-0062-7

摘要： Based on the comparative analysis of end effect on skin friction of displacement-pile (driven pile), the end effect on skin friction of bored pile is studied. The end effect on skin friction between driven pile and bored pile is different and the end effect on skin friction of bored pile is reduce of skin friction in the soil layer adjacent to the pile end. The degradation degree of skin friction is deduced with the increase of the distance from pile end. The concept of additional mud cake formed by the effect of cushion at the bottom of borehole during pouring concrete is introduced to explain the mechanism of end effect on skin friction of the bored pile. The test results of post-grouting piles indicate that the post-grouting technique is an effective way to improve the end effect on skin friction of bored pile.

关键词： distance different concept additional bottom

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Creation and integration mechanism of instrumentation flexible developing system

Xiaoli XU, Qiushuang LIU

《机械工程前沿（英文）》 2011年第6卷第2期页码 235-240 doi: 10.1007/s11465-011-0122-5

摘要：

To solve many key technical problems during the development of modern instrumentation system integration and provide a new mode and fundamental technical equipment for the research and development (R&D) of modern instrumentation products, based on the concept of an instrumentation flexible developing system (IFDS), this paper discusses the creation and open flexible integration mechanism, perfects the integrated supporting environment and integrated system of the flexible interconnection, and constructs the new flexible integrated system. Based on the operation mechanism of the modern instrumentation developing system and the research and optimization of the rapid integration design method, the paper emphasizes the dynamic integrating method of multiple types of knowledge in a modern instrument R&D system, to effectively utilize the rich integrated resource and achieve rapid integration of the system. Applications show that the new IFDS can improve the integration level and efficiency of R&D of the modern instrumentation system, enforce the reliability of the system, shorten the R&D period, and reduce the development costs.

关键词： modern instrumentation developing flexible interconnection flexible integration mechanism rapid integration system dynamic integrating method

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Review on flexible perovskite photodetector: processing and applications

《机械工程前沿（英文）》 2023年第18卷第2期 doi: 10.1007/s11465-023-0749-z

摘要： Next-generation optoelectronics should possess lightweight and flexible characteristics, thus conforming to various types of surfaces or human skins for portable and wearable applications. Flexible photodetectors as fundamental devices have been receiving increasing attention owing to their potential applications in artificial intelligence, aerospace industry, and wise information technology of 120, among which perovskite is a promising candidate as the light-harvesting material for its outstanding optical and electrical properties, remarkable mechanical flexibility, low-cost and low-temperature processing methods. To date, most of the reports have demonstrated the fabrication methods of the perovskite materials, materials engineering, applications in solar cells, light-emitting diodes, lasers, and photodetectors, strategies for device performance enhancement, few can be seen with a focus on the processing strategies of perovskite-based flexible photodetectors, which we will give a comprehensive summary, herein. To begin with, a brief introduction to the fabrication methods of perovskite (solution and vapor-based methods), device configurations (photovoltaic, photoconductor, and phototransistor), and performance parameters of the perovskite-based photodetectors are first arranged. Emphatically, processing strategies for photodetectors are presented following, including flexible substrates (i.e., polymer, carbon cloth, fiber, paper, etc.), soft electrodes (i.e., metal-based conductive networks, carbon-based conductive materials, and two-dimensional (2D) conductive materials, etc.), conformal encapsulation (single-layer and multilayer stacked encapsulation), low-dimensional perovskites (0D, 1D, and 2D nanostructures), and elaborate device structures. Typical applications of perovskite-based flexible photodetectors such as optical communication, image sensing, and health monitoring are further exhibited to learn the flexible photodetectors on a deeper level. Challenges and future research directions of perovskite-based flexible photodetectors are proposed in the end. The purpose of this review is not only to shed light on the basic design principle of flexible photodetectors, but also to serve as the roadmap for further developments of flexible photodetectors and exploring their applications in the fields of industrial manufacturing, human life, and health care.

关键词： photodetector perovskite flexible processing application

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A review of the scalable nano-manufacturing technology for flexible devices

Wenbin HUANG,Xingtao YU,Yanhua LIU,Wen QIAO,Linsen CHEN

《机械工程前沿（英文）》 2017年第12卷第1期页码 99-109 doi: 10.1007/s11465-017-0416-3

摘要：

Recent advances in electronic and photonic devices, such as artificial skin, wearable systems, organic and inorganic light-emitting diodes, have gained considerable commercial and scientific interest in the academe and in industries. However, low-cost and high-throughput nano-manufacturing is difficult to realize with the use of traditional photolithographic processes. In this review, we summarize the status and the limitations of current nano-patterning techniques for scalable and flexible functional devices in terms of working principle, resolution, and processing speed. Finally, several remaining unsolved problems in nano-manufacturing are discussed, and future research directions are highlighted.

关键词： flexible nano-manufacturing flexible devices nanofabrication scalability

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Analytical dynamic solution of a flexible cable-suspended manipulator

Mahdi BAMDAD

《机械工程前沿（英文）》 2013年第8卷第4期页码 350-359 doi: 10.1007/s11465-013-0271-9

摘要：

Cable-suspended manipulators are used in large scale applications with, heavy in weight and long in span cables. It seems impractical to maintain cable assumptions of smaller robots for large scale manipulators. The interactions among the cables, platforms and actuators can fully evaluate the coupled dynamic analysis. The structural flexibility of the cables becomes more pronounced in large manipulators. In this paper, an analytic solution is provided to solve cable vibration. Also, a closed form solution can be adopted to improve the dynamic response to flexibility. The output is provided by the optimal torque generation subject to the actuator limitations in a mechatronic sense. Finally, the performance of the proposed algorithm is examined through simulations.

关键词： parallel robot flexible cable suspended robot dynamic

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Possible role of power-to-heat and power-to-gas as flexible loads in German medium voltage networks

Mark KUPRAT, Martin BENDIG, Klaus PFEIFFER

《能源前沿（英文）》 2017年第11卷第2期页码 135-145 doi: 10.1007/s11708-017-0472-8

摘要： Germany’s energy transition triggered a rapid and unilateral growth of renewable energy sources (RES) in the electricity sector. With increasing shares of intermittent RES, overcapacities during periods of strong wind and photovoltaic electricity generation occur. In the face of insufficient transmission capacities, due to an inhibited network extension, the electricity generation has to be curtailed. This curtailment of RES leads to economic losses and could be avoided through flexible loads. As an option to cope with those problems, the technologies of power-to-gas (PtG) and power-to-heat (PtH) are presented in this paper. First, the alkaline electrolyzer (AEL), polymer electrolyte membrane electrolyzer (PEMEL), and solid oxide electrolyzer cell (SOEC) are investigated regarding their operational parameters. Second, the electric boiler, electrode heating boiler, and heat pumps are considered. Ultimately, the network-supporting abilities and the potential to provide ancillary services, such as control power, load sequence operation, cold start and part load capability, are compared among one another.

关键词： power-to-gas power-to-heat flexible loads ancillary services coherent energy systems

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Behavior of concrete-filled double skin steel tubular columns with octagon section under axial compression

YANG Junjie, PENG Guojun, XU Hanyong

《结构与土木工程前沿（英文）》 2008年第2卷第3期页码 205-210 doi: 10.1007/s11709-008-0035-5

摘要： Based on some conclusions of two kinds of concrete-filled double skin steel tube (CFDSST) members with circular or square sections, a new kind of CFDSST with octagonal section, where the outer tube has an octagonal section and the inner tube has a circular section, is proposed in this paper. Behaviors of the CFDSST members with octagon section subjected to axial compression are investigated, and some curves of load-strain of steel tubes and confined concrete and the bearing capacity of members are obtained. It is indicated that the bearing capacity of the columns with octagonal section is larger than that with square section and is smaller than that with circular section, and the bearing capacity of members is related to the ratio of the straight side to the bevelled one. Based on the proper stress-strain relationship, a couple of numerical analyses are made using the finite element software named ANSYS. Finally, a simplified formula is proposed in the paper, and the numerical results agree well with the experimental results and the mathematical solutions. The results are valuable for engineers.

关键词： mathematical numerical compression stress-strain relationship straight