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Modularized multibody multirotor for independent attitude and position control*
No full textThis paper presents the novel design and development of a multibody multirotor (MBMR) capable of controlling orientation independent of the position by tilting the passive thrust vector without any additional actuators. Conventional multirotors have a limitation in controlling the orientation independently of the position control. In particular, it is important to control the orientation independently since it affects flight efficiency and mission. Thus, various tiltrotors have been developed to control the orientation independently but require additional servo motors. The MBMR consists of a main fuselage and thrust modules without a servo motor. Each of the thrust modules can be utilized by a conventional quadrotor with four rotors connected to the fuselage by passive rotational joints. Two thrust modules, the minimum to form the MBMR, are implemented to demonstrate performance. Toward usability of the MBMR, a hierarchical control system is developed to compute relative thrust and moment vectors with respect to the fuselage. Thrust heading alignment control (THAC) is proposed to overcome a lack of roll angle control. The control system allows the heading angle of the MBMR to track the direction of thrust force so that it can maintain the near-zero tilt angle of the fuselage while generating acceleration. Experimental validation is implemented demonstrating the performance of the MBMR with independent orientation control. It is successfully achieved to regulate the fuselage's pitch angle at 80 degrees angle and track the circular trajectory within the fuselage's tilt angle under 2.6 degrees angle
Superprotonic Conductivity of MOFs Confining Zwitterionic Sulfamic Acid as Proton Source and Conducting Medium
No full textA few metal-organic frameworks (MOFs), which typically use strong acids as proton sources, display superprotonic conductivity (approximate to 10(-1) S cm(-1)); however, they are rare due to the instability of MOFs in highly acidic conditions. For the first time, we report superprotonic conductivity using a moderately acidic guest, zwitterionic sulfamic acid (HSA), which is encapsulated in MOF-808 and MIL-101. HSA acts not only as a proton source but also as a proton-conducting medium due to its extensive hydrogen bonding ability and zwitterion effect. A new sustained concentration gradient method results in higher HSA encapsulation compared to conventional methods, producing 10HSA@MOF-808-(bSA)(2) and 8HSA@MIL-101. These MOFs show impressive superprotonic conductivity of 2.47x10(-1) and 3.06x10(-1) S cm(-1), respectively, at 85 degrees C and 98 % relative humidity, and maintain stability for 7 days
Textured Ceramics for Multilayered Actuator Applications: Challenges, Trends, and Perspectives
No full textPiezoelectric actuators, which utilize piezoelectric crystals or ceramics, are commonly used in precision positioning applications, offering high-speed response and precise control. However, the use of low-performance ceramics and expensive single crystals is limiting their versatile use in the actuator market, necessitating the development of both high-performance and cost-effective piezoelectric materials capable of delivering higher forces and displacements. The use of textured Pb (lead)-based piezoelectric ceramics formed by so-called templated grain growth method has been identified as a promising strategy to address the performance and cost issue. This review article provides insights into recent advances in texturing Pb-based piezoelectric ceramics for improved performance in actuation applications. We discussed the relevant issues in detail focusing on current challenges and emerging trends in the textured piezoelectric ceramics for their reliability and performance in actuator applications. We discussed in detail focusing on current challenges and emerging trends of textured piezoelectric ceramics for their reliability and performance in actuator applications. In conclusion, the article provides an outlook on the future direction of textured piezoelectric ceramics in actuator applications, highlighting the potential for further success in this field
Nematic Fibrin Fibers Enabling Vascularized Thrombus Implants Facilitate Scarless Cutaneous Wound Healing
No full textAutologous implantable scaffolds that induce vasculogenesis have shown great potential in tissue regeneration; however, previous attempts mainly relied on cell-laden hydrogel patches using fat tissues or platelet-rich plasma, which are insufficient for generating a uniform vasculature in a scalable manner. Here, implantable vascularized engineered thrombi (IVETs) are presented using autologous whole blood, which potentiate effective skin wound healing by constructing robust microcapillary vessel networks at the wound site. Microfluidic shear stresses enable the alignment of bundled fibrin fibers along the direction of the blood flow streamlines and the activation of platelets, both of which offer moderate stiffness of the microenvironment optimal for facilitating endothelial cell maturation and vascularization. Rodent dorsal skin wounds patched with IVET present superior wound closure rates (96.08 +/- 1.58%), epidermis thickness, collagen deposition, hair follicle numbers, and neutrophil infiltration, which are permitted by enhanced microvascular circulation. Moreover, IVET treatment accelerates wound healing by recruiting M2 phenotype macrophages
Theoretical modeling for piezoresistive behavior of aligned carbon nanotube/polymer nanocomposites accounting for evolution of agglomerates morphology
No full textIn this study, the electromechanical response of carbon nanotube (CNT)-reinforced polymer nanocomposites subjected to uniaxial deformation was investigated theoretically. For this purpose, a comprehensive analytical model that incorporated critical factors affecting the piezoresistive properties of CNT/polymer nanocomposites was proposed. To determine the effects of field-induced CNT alignment and the corresponding prolonged agglomeration morphology, an effective resistor network was established to predict piezoresistivity defined as the normalized resistance change of CNT/polymer nanocomposites. The proposed model accurately described the piezoresistive properties of randomly aligned CNT-based composites compared with a previously developed model, and its further validation was performed using experimental data obtained from the literature for CNTs aligned in a polymer matrix. A similar approach was used for the determination of a percolation threshold, which strongly correlated with piezoresistivity. In addition, the effect of each individual critical factor was examined to establish a desirable set of parameters that would either decrease the percolation threshold or increase the piezoresistivity of composites
Rapid and Simple Live/Dead Bacteria Distinction Using PMA Molecule and Leuco Crystal Violet for Naked Eye Detection
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