Design and Analysis of a Compact Piezo-actuated Microgripper with a Large Amplification Ratio

Abstract This paper presents a piezo-actuated microgripper characterized by large amplification ratio and compact structure size. The microgripper is actuated by a piezo-stack actuator that is integrated with a two-stage displacement amplifier to achieve large travel range. A new design methodology “flexure hinge individualized design” (FHID) was proposed to realize large amplification ratio. According to this methodology, each flexure hinge was designed personally based on force condition of the piviot to reconfigure the motion stiffness of the compliant microgripper so that the parasitic motion and displacement loss could be eliminated. Consequently, a 52-amplification-ratio amplifier was obtained. The developed microgripper was modeled via kinematics and Castigliano's displacement theorem, respectively. Finite element analysis and the experimental studies were conducted to evaluate the characteristics of the microgripper. The results show that the motion stroke of the gripper-tip is 917 μm, and the structure dimension is 62 mm × 42 mm ×12 mm. The design methodology FHID is generic and can be extended to other compliant mechanisms.

Evaluating a Human Ear-Inspired Sound Pressure Amplification Structure with Fabry–Perot Acoustic Sensor Using Graphene Diaphragm

In order to enhance the sensitivity of a Fabry–Perot (F-P) acoustic sensor without the need of fabricating complicated structures of the acoustic-sensitive diaphragm, a mini-type external sound pressure amplification structure (SPAS) with double 10 μm thickness E-shaped diaphragms of different sizes interconnected with a 5 mm length tapered circular rod was developed based on the acoustic sensitive mechanism of the ossicular chain in the human middle ear. The influence of thickness and Young’s modulus of the two diaphragms with the diameters of 15 mm and 3 mm, respectively, on the amplification ratio and frequency response were investigated via COMSOL acoustic field simulation, thereby confirming the dominated effect. Then, three kinds of dual-diaphragm schemes relating to steel and thermoplastic polyurethanes (TPU) materials were introduced to fabricate the corresponding SPASs. The acoustic test showed that the first scheme achieved a high resonant response frequency with lower acoustic amplification due to strong equivalent stiffness; in contrast, the second scheme offered a high acoustic amplification but reduced frequency range. As a result of sensitivity enhancement, adapted with the steel/TPU diaphragm structure, an optical fiber Fabry–Perot sensor using a multilayer graphene diaphragm with a diameter of 125 μm demonstrated a remarkable sensitivity of 565.3 mV/Pa @1.2 kHz due to the amplification ratio of up to ~29.9 in the range of 0.2–2.3 kHz, which can be further improved by miniaturizing structure dimension, along with the use of microstructure packaging technology.

BASIC CLASSIFIERS OF FORMAL CLASSIFICATION THEORY OF TECHNICAL SYSTEMS: HIERARCHIES, VECTORS AND MATRICES, BANDS

The article considers the importance of a technical system among other technical systems in order to ensure its functioning and development, to classify objects, subjects, processes of the technical and related systems. Previously, the author presented the basics of the formal classification theory. This article describes the basic classifiers and operations with them. Three types of basic classifications are identified: discrete hierarchical, discrete matrix and continuous band classifications. For them the concept, structure, dimension, basic operations (addition, multiplication, equality) are defined. In the hierarchy, the classification attributes can be sorted by subordination, when the classification attributes of the lower levels of the hierarchy detail the features of higher levels. The dimension of the hierarchical classification is the number of levels of classification features. Matrix classifications (including vector and super-matrix) are used when the classification attributes are equal and their values are discrete. Band classifications are similar in structure to matrix classifications, but the value of the classification attribute is the interval of numbers, for which the lower and upper boundaries are determined. The dimension of the matrix and band classifications is equal to the number of non-subordinate classification attributes. For all classifications, multiplication is equivalent to the introduction of new classification attributes, addition is the introduction of new values of already existing classification attributes. A unified approach to various types of classifications makes it possible to plan the structure of classifications of specific technical systems, taking into account the properties of characteristic parameters

Protean career attitude and organisational commitment in learning organisation climate

PurposeThis study aims to identify the relationship between protean career attitude (PCA) and organisational commitment (OC) in a learning organisation (LO) climate. The study also identified whether negative relationships exist between the structure dimension of LO (SDLO) and PCA, and between PCA and OC, and whether such relationships can be moderated by the people dimension of LO (PDLO).Design/methodology/approachData collected from 305 employees of 26 firms were analysed using the PROCESS macro for SPSS.FindingsThis study found that SDLO had a negative relationship with PCA, whereas PCA was negatively associated with OC. Furthermore, this study found that PDLO moderated these relationships, in that the negative relationships were absent when PDLO activities were stronger, in contrast to when they were weaker.Originality/valueThe study is among the first to identify the negative relationships that exist between SDLO and PCA and between PCA and OC in Korean firms. An important implication for managers or OD professionals is that PDLO plays an important role in not only reducing the negative mediation effects of PCA in the relationships but also making the relationships positive.

Patient perceived quality of nursing care in hemodialysis: A meta-synthesis

This study was done with the purpose of clarifying the concept of patient perceived quality of nursing care in hemodialysis. In this meta-synthesis study, qualitative studies was searched in the four interntional databases from January 1st, 2000 to December 30th, 2019. The keywords used were: nursing care quality, and hemodialysis. Studies which had been done with the purpose of understanding the patient perceived quality of nursing care concept aomg hemodialysis patients were included. Two researchers were evaluate the quality of included studies separately using JBI tool, required information were extracted using the designed table. The main themes in the structure dimension include Sufficient Human resource, quality of equipment, financial support from patient and quality of the patient care environment. Process dimension consisted of continuous monitoring of the syndromes, effective patient education, efficient care, effective therapeutic relationship, and patient’s empowerment and participation in the process, and in the outcome dimension included high dialysis adequecy, patient burnout reduction, and increased patient satisfaction from services. The results of the study indicated a comprehensive, deep and interactive dimensions about the concept of nursing quality of care.

Data Encoding Improvement and Size Reduction of Chipless RFID Tag Using Short-circuit Line Effect and Angle-based Divided Loops

This paper focuses on a short circuit and concentric loop effects to improve the structure dimension as well as enhance the ability to encode electromagnetic wave data for chipless RFID tags. The tag is composed of star-shaped rings that are concentrically nested together. The following factors help reduce the tag size: using the phenomenon of electromagnetic backscattering, assessment by the Radar Cross Section (RCS), the antenna-free tag only includes the multi-frequency resonators. By inserting short circuit lines combined with concentric loops, the number of resonant peaks increases exponentially without increasing the tag overall dimension. In addition, by inserting the short circuit lines at different angles between the two consecutive loops, we can adjust the resonant frequency in the frequency bands, thereby changing the value of the bit by shifting the frequency position. The overall dimension of the resulted tag is 13mmx13 mm and the tag is aimed to be a printable tag on the flexible substrate to minimize the fabrication cost. With the 18-vertex star-shaped tag with five concentric loops, this chipless RFID tag can encode up to 16 bits with high resolution and large data density.

Study on Twining Technologies Adopted by Bamboo Sutra Wrappers of the Tang Dynasty

Bamboo sutra wrapper is made of bamboo splints fastened together with silk threads using the warp twining method. Bamboo sutra wrappers dating to the Tang and Song dynasties are mainly found in Cave 17. They are usually in a rectangular shape with the geometrical, dotted or floral pattern which are quite favored in the Tang dynasty. Affected by Buddhism, sutra wrappers of this kind have also been found in other Asian countries such as Japan and Korea, with a similarity in structure, dimension and twining method.