Lead-free multilayer piezoelectric transformer

In this article, a multilayer piezoelectric transformer based on lead-free Mn-doped 0.94(Bi[sub ½]Na[sub ½])TiO₃-0.06BaTiO₃ ceramics is presented. This piezoelectric transformer, with a multilayered construction in the thickness direction, is 8.3 mm long, 8.3 mm wide, and 2.3 mm thick. It operates in the second thickness extensional vibration mode. For a temperature rise of 20°C, the transformer has an output power of >0.3 W. With a matching load resistance of 10 Ω, its maximum efficiency approaches 81.5%, and the maximum voltage gain is 0.14. It has potential to be used in low voltage power supply units such as low power adapter and other electronic circuits.Department of Applied PhysicsMaterials Research CentreAuthor name used in this publication: K. H. LamAuthor name used in this publication: S. WangAuthor name used in this publication: C. L. SunAuthor name used in this publication: X. Z. Zha

Community Participation and Residents’ Support for Tourism Development in Ancient Villages: The Mediating Role of Perceptions of Conflicts in the Tourism Community

As increasing numbers of tourists have begun to visit ancient villages, conflicts between tourism development and residents have become one of the main challenges to the sustainable development of the tourism community. This research explores the relationship between community participation and residents’ support for tourism development in an ancient village. This study surveyed 249 indigenous residents living in Whampoa Village, Guangzhou, China. The findings show that community participation in tourism development has a positive influence on residents’ support for tourism development, and this relationship is mediated by the perceptions of conflicts in the tourism community. This study contributes a new theoretical perspective and practical implications for the sustainable development of ancient villages

Validating Precise Orbit Determination from Satellite-Borne GPS Data of Haiyang-2D

Haiyang-2D (HY-2D) is the fourth satellite in the marine dynamic satellite series established by China. It was successfully launched on 19 May 2021, marking the era of the 3-satellite network in the marine dynamic environment satellite series of China. The satellite’s precision orbit determination (POD) and validations are of great significance for ocean warning and marine altimetry missions. HY-2D is equipped with a laser reflector array (LRA), a satellite-borne Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) receiver, and a satellite-borne dual-frequency GPS receiver named HY2 that was independently developed in China. In this paper, the quality of GPS data collected by the HY2 is analyzed based on indicators such as the multipath effect, cycle slips, and data completeness. The results suggest that the receiver can be used in POD missions involving low-Earth-orbit (LEO) satellites. The precise orbits of HY-2D are determined by the reduced-dynamics (RD) method. Apart from POD, validation of orbit accuracy is another important task for LEO POD. Therefore, two external validation methods are proposed, including carrier differential validation using one GPS satellite and inter-satellite differential validation using two GPS satellites. These are based on space-borne carrier-phase data, and the GPS satellites used for POD validation do not participate in orbit determination. The results of SLR range validation cannot illustrate the orbit accuracy in x, y, and z directions particularly, so to make validation results more intuitive, the SLR three-dimensional (3D) validation is proposed based on SLR range validation, and the RMSs in x, y, and z directions are 2.66, 3.32, and 2.69 cm, respectively. The results of SLR 3D validation are the same as those of SLR range validation, which proves that the new external validation method provided by SLR 3D is reliable. The RMSs of carrier differential validation and inter-satellite differential validation are 0.68 and 1.06 cm, respectively. The proposed validation methods are proved to be reliable

On Satellite-Borne GPS Data Quality and Reduced-Dynamic Precise Orbit Determination of HY-2C: A Case of Orbit Validation with Onboard DORIS Data

Haiyang-2C (HY-2C) is a dynamic, marine-monitoring satellite that was launched by China and is equipped with an onboard dual-frequency GPS receiver named HY2_Receiver, which was independently developed in China. HY-2C was successfully launched on 21 September 2020. Its precise orbit is an important factor for scientific research applications, especially for marine altimetry missions. The performance of the HY2_Receiver is assessed based on indicators such as the multipath effect, ionospheric delay, cycle slip and data utilization, and assessments have suggested that the receiver can be used in precise orbit determination (POD) missions involving low-Earth-orbit (LEO) satellites. In this study, satellite-borne GPS data are used for POD with a reduced-dynamic (RD) method. Phase centre offset (PCO) and phase centre variation (PCV) models of the GPS antenna are established during POD, and their influence on the accuracy of orbit determination is analysed. After using the PCO and PCV models in POD, the root mean square (RMS) of the carrier-phase residuals is around 0.008 m and the orbit overlap validation accuracy in each direction reaches approximately 0.01 m. Compared with the precise science orbit (PSO) provided by the Centre National d’Etudes Spatiales (CNES), the RD orbit accuracy of HY-2C in the radial (R) direction reaches 0.01 m. The accuracy of satellite laser ranging (SLR) range validation is better than 0.03 m. Additionally, a new method is proposed to verify the accuracy of the RD orbit of HY-2C by using space-borne Doppler orbitography and radiopositioning integrated by satellite (DORIS) data directly. DORIS data are directly compared to the result calculated using the accurate coordinates of beacons and the RD orbit, and the results indicate that the external validation of HY-2C RD orbit has a range rate accuracy of within 0.0063 m/s

A study on the disk-shaped piezoelectric transformer with multiple outputs

In this study, a modified disk-shaped multiple-output piezoelectric transformer operated at the fundamental radial vibration mode has been presented. A derived equivalent circuit for the multioutput piezoelectric transformer was used to analyze the performance. Two piezoelectric transformers, a symmetrically electroded piezoelectric transformer with dual outputs and an asymmetrically electroded piezoelectric transformer with triple outputs, were fabricated with lead zirconate titanate piezoelectric ceramics. The characteristics of the two piezoelectric transformers were investigated experimentally. The piezoelectric transformer with multiple outputs has potential to be used in power supply units and other electronic circuits

A lead-free piezoelectric transformer in radial vibration modes

In this study, a disk-shaped piezoelectric transformer was fabricated using lead-free (K, Na)Nbo3-based ceramics with high mechanical quality factor. The transformer can operate in the fundamental or the third radial vibration mode. The transformer is poled along the thickness direction. The top surface is covered by ring/dot silver electrodes separated by an annular gap which serve as the input and output parts of the transformer, respectively. The bottom surface, fully covered with a silver electrode, is grounded as a common electrode. The dimensions of the top ring/dot electrodes are designed such that the third radial vibration mode can be strongly excited. The electrical properties of the transformer with diameter of 34.2mm and thickness of 1.9mm were measured. For a temperature rise of 35°C⁠, the transformer has a maximum output power of 12W⁠. With the matching load, its maximum efficiency is >95%⁠, and maximum voltage gains are 6.5 and 3.9 for the fundamental and the third radial vibration modes, respectively. It has potential to be used in power supply units and other electronic circuits

Lead-free multilayer piezoelectric transformer

In this article, a multilayer piezoelectric transformer based on lead-free Mn-doped 0.94(Bi1/2Na1/2)TiO3-0.06 BaTiO3 ceramics is presented. This piezoelectric transformer, with a multilayered construction in the thickness direction, is 8.3mm long, 8.3mm wide, and 2.3mm thick. It operates in the second thickness extensional vibration mode. For a temperature rise of 20°C⁠, the transformer has an output power of >0.3W⁠. With a matching load resistance of 10Ω⁠, its maximum efficiency approaches 81.5%, and the maximum voltage gain is 0.14. It has potential to be used in low voltage power supply units such as low power adapter and other electronic circuits

A Rosen-type piezoelectric transformer employing lead-free K(0.5)Na(0.5)NbO(3) ceramics

Lead-free K0.5Na0.5NbO3–K5.4Cu1.3Ta10O29–MnO2 (KNN–KCT–Mn) ceramics have been prepared by a conventional ceramic sintering technique. The ceramics show excellent piezoelectric properties for application in power devices, and the optimum properties measured are as follows: piezoelectric constant d 33 = 90 pC/N, planar electromechanical coupling factor k p = 0.40, mechanical quality factor Q m = 1900, remanent polarization P r = 11.8 μC/cm2, coercive field E c = 0.85 kV/mm. A Rosen-type piezoelectric transformer with a dimension of 21 mm × 6 mm × 1.2 mm was fabricated using the KNN–KCT–Mn ceramics. Properties of the piezoelectric transformer operating in the first and second modes have been characterized. For the first mode, the transformer has a maximum output power of 0.7 W with a temperature rise of 14 °C. For the second mode, the maximum output power of the transformer is 1.8 W with a temperature rise of 33 °C. KNN–KCT–Mn ceramics have shown to be a potential lead-free candidate to be used in high-voltage–low-current devices