scholarly journals Elastic Actuator Design Based on Bending of Cylindrical Beam for Robotic Applications

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 80
Author(s):  
Reis Murat ◽  
Nafiseh Ebrahimi ◽  
Amir Jafari
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Variable Stiffness ◽  
Circular Disk ◽  
Torsional Stiffness ◽  
Steel Beams ◽  
Elastic Coupling ◽  
Stiffness Characteristics ◽  
Living Organisms ◽  
Mechanical Devices

The lack of suitable actuators has hampered the development of high-performance machines or robots that can compete with living organisms in terms of motion, safety, and energy efficiency. The adaptation properties of biological systems to environmental variables—for example, the control performance of biological muscle with variable stiffness properties—exceeds the performance of mechanical devices. The variable stiffness characteristics of elastic actuators are different from the operating principle of conventional solids. Although there has been a lot of work on the design of elastic actuators in recent years, a low-cost and compact elastic actuator that can be used in place of standard rigid servo actuators is not yet available. In this study, a standard servo motor has been transformed into an elastic actuator by an elastic coupling attached to the gear system. The elastic coupling consists of four small steel beams with a cylindrical cross section placed on the circular disk, and the stiffness of the actuator is adjusted by varying the clutch length of the cylindrical beams. In this study, this innovative design is explained, then the equations expressing the variation of the torsional stiffness of the cylindrical beams with the coupling length and solutions of these equations are given. The experimental results are presented to show the ability of the proposed actuator to control position and regulate the stiffness independently.

Symmetry Design in Flexure Systems Using Kinematic Principles

2013 ◽  
Author(s):  
Jingjun Yu ◽  
Shouzhong Li ◽  
Shusheng Bi ◽  
Guanghua Zong
Keyword(s):  
High Performance ◽  
Screw Theory ◽  
Mathematical Explanation ◽  
Symmetrical Design ◽  
Dynamic Performances ◽  
Living Organisms ◽  
Improving Accuracy ◽  
Mechanical Devices ◽  
Effective Use

Inspiration for the creation of mechanical devices often comes from observing the natural structures and movements of living organisms. Understanding the wide use of modularity and compliance in nature may lead to the design of high-performance flexure systems or compliant devices. One of the most important nature-inspired paradigms for constructing flexure systems is based on the effective use of symmetry. With a rigid mathematical foundation called screw theory and Lie group. The research of this paper mainly focuses on: (i) Mathematical explanation or treatment of symmetry design wildly used in flexure systems, concerning with a series of topics such as the relationship between degree of freedom (DOF), constraint, overconstraint, decouple motion and symmetrical geometry, and How to guarantee the mobility unchanged when using symmetry design? (ii) A compliance-based analytical verification for demonstrating that the symmetry design can effectively improve accuracy and dynamic performances. (iii) The feasibility of improving accuracy performance by connecting symmetry design with the principle of elastic averaging. The whole content is organized around a case study, i.e. symmetrical design of 1-DOF translational flexure mechanisms. The results are intent to provide a rigid theoretical foundation and significant instruction for the symmetry design philosophy in flexure systems using kinematic principles.

scholarly journals RFID-Based Crack Detection of Ultra High-Performance Concrete Retrofitted Beams

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1573 ◽  
Author(s):  
Benjamin Bruciati ◽  
Shinae Jang ◽  
Pierre Fils
Keyword(s):  
High Performance ◽  
Crack Detection ◽  
High Performance Concrete ◽  
Low Cost ◽  
Damage Index ◽  
Steel Beams ◽  
Ultra High Performance Concrete ◽  
Novel Material ◽  
New Material ◽  
The 1960S

Ultra-high-performance concrete (UHPC) is a novel material with multiple known uses and many still yet to be discovered. Recently, the use of encasing welded shear studs in UHPC on the web of corroded steel beams was developed. This creates a bearing force transfer mechanism to bypass the corroded web plate. This new material and its uses come with many uncertainties in the short and long term. Structural health monitoring (SHM) can be a tool to observe the development. Specifically, radio frequency technology (RFID) can be used. RFID has existed commercially since the 1960s and has been used as a crack sensor before, but never with UHPC. RFID-based crack sensing is being used to monitor the UHPC retrofit. A crack is simulated on the UHPC specimen and then a commercial, low cost tag is secured. Using backscatter power, the tag reads the crack existence and its increasing volume with every new damage stage. Using a damage index, comparing the uncracked and each cracked stage, this method is not restricted to the raw received signal strength indicator (RSSI), which could be different at each tag. With this sensor, the small cracks that occur in UHPC during its creation can be monitored to ensure the capacity of the retrofitting is maintained. The tested RFID-based crack sensor can be used on various other forms of UHPC.

Comparison of UV- and Derivative-Spectrophotometric and HPTLC UVDensitometric Methods for the Determination of Amrinone and Milrinone in Bulk Drugs

2020 ◽  
Vol 16 (3) ◽  
pp. 246-253
Author(s):  
Marcin Gackowski ◽  
Marcin Koba ◽  
Stefan Kruszewski
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
High Performance ◽  
Low Cost ◽  
Uv Spectra ◽  
Derivative Spectrophotometry ◽  
Therapeutic Monitoring ◽  
Bulk Drug ◽  
Layer Chromatography ◽  
Standard Solutions

Background: Spectrophotometry and thin layer chromatography have been commonly applied in pharmaceutical analysis for many years due to low cost, simplicity and short time of execution. Moreover, the latest modifications including automation of those methods have made them very effective and easy to perform, therefore, the new UV- and derivative spectrophotometry as well as high performance thin layer chromatography UV-densitometric (HPTLC) methods for the routine estimation of amrinone and milrinone in pharmaceutical formulation have been developed and compared in this work since European Pharmacopoeia 9.0 has yet incorporated in an analytical monograph a method for quantification of those compounds. Methods: For the first method the best conditions for quantification were achieved by measuring the lengths between two extrema (peak-to-peak amplitudes) 252 and 277 nm in UV spectra of standard solutions of amrinone and a signal at 288 nm of the first derivative spectra of standard solutions of milrinone. The linearity between D252-277 signal and concentration of amironone and 1D288 signal of milrinone in the same range of 5.0-25.0 μg ml/ml in DMSO:methanol (1:3 v/v) solutions presents the square correlation coefficient (r2) of 0,9997 and 0.9991, respectively. The second method was founded on HPTLC on silica plates, 1,4-dioxane:hexane (100:1.5) as a mobile phase and densitometric scanning at 252 nm for amrinone and at 271 nm for milrinone. Results: The assays were linear over the concentration range of 0,25-5.0 μg per spot (r2=0,9959) and 0,25-10.0 μg per spot (r2=0,9970) for amrinone and milrinone, respectively. The mean recoveries percentage were 99.81 and 100,34 for amrinone as well as 99,58 and 99.46 for milrinone, obtained with spectrophotometry and HPTLC, respectively. Conclusion: The comparison between two elaborated methods leads to the conclusion that UV and derivative spectrophotometry is more precise and gives better recovery, and that is why it should be applied for routine estimation of amrinone and milrinone in bulk drug, pharmaceutical forms and for therapeutic monitoring of the drug.

Azo (Hydrazone) pigments: general principles

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Robert Christie
Keyword(s):  
High Performance ◽  
Metal Salt ◽  
Low Cost ◽  
Cost Effective ◽  
Precipitation Process ◽  
Ambient Temperatures ◽  
Technical Performance ◽  
Chemical Structures ◽  
General Chemical ◽  
Physical Form

Abstract This paper presents an overview of the general chemical principles underlying the structures, synthesis and technical performance of azo pigments, the dominant chemical class of industrial organic pigments in the yellow, orange, and red shade areas, both numerically and in terms of tonnage manufactured. A description of the most significant historical features in this group of pigments is provided, starting from the discovery of the chemistry on which azo colorants are based by Griess in the mid-nineteenth century, through the commercial introduction of the most important classical azo pigments in the early twentieth century, including products known as the Hansa Yellows, β-naphthol reds, including metal salt pigments, and the diarylide yellows and oranges, to the development in the 1950s and 1960s of two classes of azo pigments that exhibit high performance, disazo condensation pigments and benzimidazolone-based azo pigments. A feature that complicates the description of the chemical structures of azo pigments is that they exist in the solid state as the ketohydrazone rather than the hydroxyazo form, in which they have been traditionally been illustrated. Numerous structural studies conducted over the years on an extensive range of azo pigments have demonstrated this feature. In this text, they are referred to throughout as azo (hydrazone) pigments. Since a common synthetic procedure is used in the manufacture of virtually all azo (hydrazone) pigments, this is discussed in some detail, including practical aspects. The procedure brings together two organic components as the fundamental starting materials, a diazo component and a coupling component. An important reason for the dominance of azo (hydrazone) pigments is that they are highly cost-effective. The syntheses generally involve low cost, commodity organic starting materials and are carried out in water as the reaction solvent, which offers obvious economic and environmental advantages. The versatility of the approach means that an immense number of products may be prepared, so that they have been adapted structurally to meet the requirements of many applications. On an industrial scale, the processes are straightforward, making use of simple, multi-purpose chemical plant. Azo pigments may be produced in virtually quantitative yields and the processes are carried out at or below ambient temperatures, thus presenting low energy requirements. Finally, provided that careful control of the reaction conditions is maintained, azo pigments may be prepared directly by an aqueous precipitation process that can optimise physical form, with control of particle size distribution, crystalline structure, and surface character. The applications of azo pigments are outlined, with more detail reserved for subsequent papers on individual products.

A binuclear Co-based metal-organic framework towards efficient oxygen evolution reaction

2021 ◽  
Author(s):  
Ning Liu ◽  
Qiaoqiao Zhang ◽  
Jingqi Guan
Keyword(s):  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
High Performance ◽  
Low Cost ◽  
Metal Organic Framework ◽  
Research Interest ◽  
Metal Organic ◽  
Organic Framework

Seeking for low-cost and high-performance electrocatalysts for oxygen evolution reaction (OER) has drawn enormous research interest in the last few years. Reported herein is the topotactic construction of a binuclear...

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