Chao Chen

Zhejiang Ocean University · Department of Marine Science

The extraction of coastal aquaculture ponds from remote sensing images is affected by the effect of ‘same object with different spectrums’ and ‘different objects with same spectrums’. The U²-Net deep learning network is able to capture more contextual information from different scales to solve this problem and is suitable for salient object detecti...

Bi0.5Na0.5TiO3-based ceramics play a pivotal role in energy storage applications due to their significant attributes, such as large maximum polarization. However, the considerable remnant polarization limits its application impulse capacitor applications. To address this limitation, we conceived and synthesized lead-free relaxor ferroelectric ceram...

It is necessary to balance the piezoelectric constant (d 33 ) and Curie temperature (T c ) of BiFeO 3 -BaTiO 3 -based lead-free ceramics. In this paper, the B-site ions substitution 0.7BiFe (1-x) Co x O 3 -0.3BaTiO 3 (BFC x -BT) ceramics were successfully prepared....

In this study, we employed the conventional solid-state reaction method to prepare high Curie temperature (Tc) lead-free piezoelectric ceramics by co-doping W⁶⁺ and Mn²⁺ into CaBi2Nb2−x(W3/4Mn1/4)xO9 (designated as CBNWM-x, with 0 ≤ x ≤ 0.08), and our focus was to enhance the electric properties, while maintaining a high Tc. The co-doping of W⁶⁺ an...

In recent few years, the two-dimensional (2D) magnets have emerged as one of the most important frontiers in materials physics and attracted much attention. As one of the earliest experimentally discovered 2D magnets, CrI3 shows a wealth of properties and has been extensively studied. In particular, an intriguing characteristic of the CrI3 monolaye...

Land resources are an essential foundation for socioeconomic development. Island land resources are limited, the type changes are particularly frequent, and the environment is fragile. Therefore, large-scale, long-term, and high-accuracy land-use classification and spatiotemporal characteristic analysis are of great significance for the sustainable...

In recent years, with the fast development of magnetic devices for information technology, the demands of magnetic thin films with both high functional stability and integration flexibility rapidly increase. It is believed that building a magnet with complementary advantages of van der Waals (vdW) and non-vdW magnets, which can be described as a “q...

K/Ce co-doped Bi4Ti3O12–Ba1−x(K1/2Ce1/2)xBi4Ti4O15 (BBIT-xKC, 0 ≤ x ≤ 0.3) intergrowth bismuth layered piezoelectric ceramics were prepared by traditional solid-state reaction. The effects of K/Ce substitution on structure, high temperature conductivity, and piezoelectric properties of BBIT were systematically investigated. The XRD results suggest...

In recent years, one of the urgent issues for two dimensional (2D) magnetic materials is to find efficient ways in enhancing the magnetic ordering temperature T c . It is believed that an in-plane (IP) compressive strain can greatly enhance the interatomic interactions by shortening the chemical bond length if at all possible, leading to the enlarg...

Lead-free BiFeO3-BaTiO3 ceramics with excellent electrical properties can be achieved by chemical doping and quenching process. In this study, 0.7Bi1.02FeO3-0.3BaTiO3 + xmol%Li2CO3/Al2O3 (BF-BT-xLiAl, 0 ≤ x ≤ 1.0) ceramics were prepared using a conventional solid-state reaction method. The influences of Li/Al substitution on the structure, defects,...

The main challenge in extracting coastal aquaculture ponds is how to weaken the influence of the “same-spectrum foreign objects” effect and how to improve the definition of the boundary and accuracy of the extraction results of coastal aquaculture ponds. In this study, a recognition model based on the U2-Net deep learning model using remote sensing...

Water, as an important part of ecosystems, is also an important topic in the field of remote sensing. Shadows and dense vegetation negatively affect most traditional methods used to extract water body information from remotely sensed images. As a result, extracting water body information with high precision from a wide range of remote sensing image...

The acquisition of dynamic information on the coastline is of great significance for the Zhoushan archipelago. However, a large amount of suspended sediments, a tortuous coastline, numerous tidal flats, and so on have brought many challenges to research involving coastline extraction and the analysis of the spatial–temporal dynamics. This study has...

The Bi7-xCexTi4.2Ta0.3W0.5O21 (BTTW-BITT-xCe, x = 0.05, 0.10, 0.15, 0.20) ceramics were studied as potential materials for high-temperature applications. The microstructure, dielectric, piezoelectric and ferroelectric properties of Ce doped BTTW-BITT samples were analyzed in detail. The results indicated that an appropriate amount of Ce ion doping...

In this work, Mg²⁺-doped CaBi2Nb2O9 (CBN-xMg) lead-free piezoceramics were prepared by a common solid-state method to investigate the effects of Mg²⁺ doping content on crystal structure, electrical resistivity, and dielectric and ferroelectric properties. XRD and Raman spectroscopy show that the Mg atoms enter the B-site to form a solid solution of...

Ba(1-x)(Na0.5Ce0.5)xBi8Ti7O27 (BBIT:x(NC)) intergrowth bismuth layer-structured piezoelectric ceramics with enhanced piezoelectric and ferroelectric properties were synthesized by the traditional solid-state reaction process. Our systematic investigations show that the BBIT:x(NC) ceramics have a single intergrowth structure with an orthogonal phase...

(NaBi)0.5-x(LiCe)xBi2Nb1.99(Co1/3W2/3)0.01O9 (NBNCW-xLC, x = 0.00–0.12) ceramic samples were obtained by (LiCe) co-doping Na0.5Bi2.5Nb1.99(Co1/3W2/3)0.01O9. The conventional solid-phase method was used throughout the preparation process. The effect of (LiCe) on the crystal structure, microscopic morphology, and dielectric, ferroelectric and piezoel...

Lead-free piezoelectric ceramics 0.7Bi1+xFeO3-0.3BaTiO3 (B1+xF-BT, 0 ≤ x ≤ 0.04) with excellent piezoelectric performance were synthesized with conventional sintering methods. The impacts of Bi compensation and sintering conditions on the structure and electrical properties of the piezoelectric ceramics were studied. The results showed that the sam...

Enhancement of the antiferroelectric phase and exhibition of a double P–E hysteresis loop of NaNbO3 (NN) has been a hot research topic in recent years. In this work, polycrystalline ceramic Na (Nb0.99M0.01) O2.995 (M = Si, Sn and Hf) was successfully prepared by solid-state reaction method. The “pinning” effect of oxygen vacancy and defect dipole i...

Ecosystem functions and services support all life on earth and are directly or indirectly related to human well-being. Meanwhile, island cities have concentrated populations, limited natural resources, and fragile environments. This study obtained land use and cover change information for an island city based on long-term series remote sensing imag...

This article reports the significantly improved piezoelectric and ferroelectric properties of Cu/W co-doped Ca2Bi2Nb2-x(Cu1/4W3/4)xO9 (CBNCW-x, where 0≤x≤0.150) high Curie temperature lead-free piezoelectric ceramics. The crystal structure, microstructure, and electric properties of CBNCW-x ceramics have been systematically analyzed. The results sh...

NaNbO3 powder was synthesized via the polyacrylamide gel method, growth behaviors and associated morphology were discussed. The calcined NaNbO3 powder at 565 °C possess cubic and long columnar morphology which are NaNbO3 and Na/Nb/F or Na/Nb/F/O compounds, respectively. According to XRD and SEM, as calcined temperature raised, the amount of F in Na...

Co/W co-doped Na0.5Bi2.5Nb2-x(Co1/3W2/3)xO9 (NBNCW-x) ceramic samples were prepared by the conventional solid state reaction method. The electrical properties and crystal structure of the NBNCW-x ceramic samples were analyzed in detail. The XRD and Rietveld refinement results showed that the samples lattice distortion decreased with the increment o...

Na0.5Bi2.5Nb2-xCoxO9 (NBNC-x, x = 0.00, 0.02, 0.05, 0.07, 0.09) bismuth layered piezoelectric ceramics were synthesized by the traditional solid-state method. The microstructure, piezoelectric, dielectric and ferroelectric properties of Co3+ doped NBNC-x ceramics were systematically investigated. The XRD results showed all ceramics possess bismuth...

Bi7Ti4.5-xTaxW0.5O21 (BTW-BIT-xTa, x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.30) intergrowth bismuth-layered ceramics were fabricated by traditional solid-phase method. The effects of Ta5+ ion doping on the structure and morphology of BTW-BIT ceramics were investigated by measuring XRD and SEM Photos. It indicated that octahedral distortion was increased...

Li/Ce co-doped BaBi4Ti4O15–Bi4Ti3O12 (BBT-BIT) intergrowth bismuth layer-structured piezoelectric ceramics were prepared by conventional solid-state method. The X-ray diffraction, Raman spectroscopy, and scanning electron microscopy results showed that all the samples had a single orthorhombic phase structure, indicating that Li/Ce dopants had succ...

Ecosystem services are the conditions in which human existence can be maintained and satisfied by natural ecosystems and their constituent species. Meanwhile, island cities have limited natural resources and fragile environments. So, more attention should be paid to the evaluation of their ecosystem service value (ESV). We propose an approach for e...

Ca1-xCexBi2Nb1.975(Cu0.25W0.75)0.025O9 (CBNCW-xCe: x = 0.00, 0.02, 0.04, 0.06, and 0.09) lead-free piezoelectric ceramics with improved piezoelectric properties were prepared by the traditional solid-state reaction method. The effects of CeO2 doping on the microstructure and electrical properties were investigated in detail. XRD patterns and Rietve...

To objectively and justly compare the results of remote-sensing image fusion, evaluate the fusion algorithm, and optimize the fusion process, a quality evaluation index system is constructed by considering both qualitative and quantitative evaluations. The quantitative evaluation indexes are divided into three types based on the analysis of evaluat...

Recently, the issue of ferromagnetism enhancement in two-dimensional (2D) van der Waals (vdW) layered magnetic systems has been highly concerned. It is believed that ion intercalation in vdW layered ferromagnets, targeting either enhanced interlayer spin exchanges or intralayer ones, can be an efficient scheme. In this work, by means of the first-p...

Attention-based deep multiple-instance learning (MIL) has been applied to many machine-learning tasks with imprecise training labels. It is also appealing in hyperspectral target detection, which only requires the label of an area containing some targets, relaxing the effort of labeling the individual pixel in the scene. This article proposes an $...

Structure and electrical properties of cerium doped bismuth barium titanate Ba1-xCexBi8Ti7O27 (x = 0, 0.05, 0.1, 0.15, 0,2 and 0.3) ceramics were investigated. X-ray diffraction revealed that the ceramic samples are of single stable phase. The ceramics possess typical plate-like structure with obvious decrease in the grain size with increasing Ce-d...

Non-invasive heart rate estimation is of great importance in daily monitoring of cardiovascular diseases. In this paper, a bidirectional long short term memory (bi-LSTM) regression network is developed for non-invasive heart rate estimation from the ballistocardiograms (BCG) signals. The proposed deep regression model provides an effective solution...

The frequent occurrence of red tides in China’s coastal areas has caused huge losses to society and economy, and seriously threatened the coastal marine environment and ecological security. Based on the data of 30 years from 1990 to 2019, this paper analyzes spatial-temporal distribution characteristics of red tide in China’s coastal areas. Our res...

Regional economic development describes the total social and economic activities in a given time and space. An objective understanding of the real regional economy is beneficial for healthy, sustainable societal development. Generally speaking, the understanding of the regional economy is mainly based on social surveying, which incurs time and ener...

Bi3−xCexTi1.5W0.5O9(BTW-xCe,0.00 ≤ x ≤ 0.10) bismuth-layered ceramics were synthesized through a conventional solid-phase reaction process. The impact of Ce ion doping on lattice structures and electrical performance of BTW-xCe ceramic sample has been discussed. All the ceramic samples show a single bismuth-layered structure. Lattice distortion was...

With the availability of multi-sensor, multi-temporal, multi-resolution and multi-spectral images from operational Earth observation satellites, remote sensing image fusion has become a valuable tool. The goal of remote sensing image fusion is to integrate complementary information from multi-source data such that the new images are more suitable f...

Chen, C.; He, X.; Lu, Y., and Chu, Y., 2020. Application of Landsat time-series data in island ecological environment monitoring: A case study of Zhoushan Islands, China. In: Yang, D.F. and Wang, H. (eds.), Recent Advances in Marine Geology and Environmental Oceanography. Journal of Coastal Research, Special Issue No. 108, pp. 193–199. Coconut Cree...

The monitoring of economic activities is of great significance for understanding regional economic development level and policymaking. As the carrier of economic activities, land resource is an indispensable production factor of economic development, and economic growth leads to increased demand for land as well as changes in land utilization form....

New types of Ce-doped CexBi7-xTi4.5W0.5O21 (BTW-BIT-xCe) Aurivillius intergrowth ceramics with high Curie temperatures were synthesized to improve the piezoelectric performances as well as the conduction behaviour, and these ceramics exhibit great potential for high-temperature lead-free piezoelectric applications. The crystal structure, electrical...

Inspired by the application of recurrent neural networks (RNNs) to image recognition, in this paper, we propose a heartbeat detection framework based on the Gated Recurrent Unit (GRU) network. In this contribution, the heartbeat detection task from ballistocardiogram (BCG) signals was modeled as a classification problem where the segments of BCG si...

In this work, we report the ultrahigh electromechanical coupling performance of NBT-6BT-KNN lead-free single crystal at room temperature. The thickness mode electromechanical coupling coefficient (kt) and the 31 mode electromechanical coupling coefficient (k31) reach 69.0% and 45.7%, respectively, which are superior to the PZT-5H lead-based ceramic...

Sea surface temperature (SST) is an important parameter used to describe the air-sea interaction and the state of marine structures. Atmospheric water vapor has a significant attenuation effect on thermal infrared information, which will reduce the accuracy of SST inversion. However, the effect of atmospheric water vapor on the inversion accuracy i...

Water body is one of the most active and important earth resources, and which has a profound impact on the natural system and human society. In order to acquire surface water body information quickly, accurately and efficiently, the method of water body information extraction using remote sensing imagery has attracted the attention of many searcher...

Rapid urbanization, marked by massive land-use and land-cover change (LUCC) and explosive population growth, has a significant impact on human activities. To provide a comprehensive understanding of the characteristics of LUCC in the Zhoushan Archipelago, dynamic monitoring and analysis of LUCC was performed using seven Landsat images from 1984 to...

Since industry‐standard piezoelectric materials, such as lead zirconium titanate ceramics, contain toxic lead, a rapid surge in research on lead‐free piezoelectric materials is occurring due to concerns over environmental safety and human health. A ternary lead‐free (Na0.5Bi0.5)TiO3‐BaTiO3‐(K0.5Na0.5)NbO3 single crystal with a large field induced s...

Bridges over water are important artificial objects that can be damaged by natural disasters. Accurate identification and damage detection of such bridges through the use of high-spatial-resolution optical remotely sensed imagery are important in emergency rescue and lifeline safety assessment. In this study, we detail a knowledge-based method of i...

Since the launch of landsat8, high-quality surface observation data have been acquired. But the corresponding sea surface temperature (SST) products have not been seen. Moreover, the existing SST inversion algorithm do not carefully consider the effect of water vapor on the accuracy. In this study, a new method is proposed for the retrieve of SST f...

An ecological environment is a complex system fundamental to the sustainable development of society and economy. Landsat series satellites are widely used for monitoring the changes in the earth’s surface morphology. With long time series data, Landsat can provide new methods and technical support for eco-environmental monitoring. This study develo...

The coastline is the dividing line between the ocean and land. Monitoring coastline dynamics is of crucial importance because it provides essential information for understanding the coastal response to contemporary climate change and human impacts. Real-time monitoring of coastlines has increasingly depended on remote sensing images at high tempora...

The effects of phase structure on up-conversion (UC) photoluminescence (PL) and dielectric properties of lead-free ceramics of Er³⁺-doped x (Bi0·5Na0.5)TiO3-(1-x)BaTiO3 (xNBT-BT: Er³⁺, 0.00 ≤ x ≤ 0.90) were investigated. X-ray diffraction and Rietveld structural refinement analyses were conducted to characterize the phase structure. On increasing t...

The study of the variation and development trend of regional oceanographic parameters is of great significance to the prevention and mitigation of disasters, the development and utilization of oceans, the guidance of human activities at sea, and the monitoring of the El Niño phenomenon. As an important fishery in China, the changes in oceanographic...

The analytical model of an axially precompressed cantilever bimorph is established using the Hamilton’s principle in this study, and the static characteristics are obtained. The dynamic equations of the cantilever bimorph in generalized coordinates are established using a numerical method, and the dynamic characteristics are analyzed. Finally, simu...

Fully polarimetric synthetic aperture radar (PolSAR) can transmit and receive electromagnetic energy on four polarization channels (HH, HV, VH, VV). The data acquired from four channels have both similarities and complementarities. Utilizing the information between the four channels can considerably improve the performance of PolSAR image classific...

The orientation dependence of the electric field induced strain and phase transitions in 0.92(Na0.5Bi0.5)TiO3–0.06BaTiO3–0.02(K0.5Na0.5)NbO3 (NBT–6BT–2KNN) single crystals has been investigated. The evolution of Raman spectra with electric field reveals that a tetragonal ferroelectric phase is initially induced at E = 14 kV/cm and completed above E...

As a dynamic belt between land and oceans, coastline provides rich information on land-ocean interactions. Sensitive to climate and anthropogenic influences, the changing coastline affects intertidal mudflat resources and the coastal environment. In this study, the greenness and wetness components of the tasseled cap transformation (TCT) were used...

A bridge over water is typically an artificial object that can be damaged by changes in landform, geology, hydrology, and other surrounding conditions. Natural disaster scenarios must be studied using high-spatial-resolution remote-sensing images to detect and assess damage to bridges over water. Such studies are important for emergency rescue oper...

CaBi8−xEux Ti7O27 (CBT-BIT-xEu3+, x = 0.00, 0.05, 0.10, 0.15, and 0.20) intergrowth-structured ceramics were synthesized using a solid-state reaction method. The intergrowth structures were successfully obtained and clearly observed by HR-TEM along the [\(\bar {1}10\)] zone axis. Raman patterns indicated that Eu3+ preferred to occupy the A sites in...

The p-wave double-frequency (DF) microseisms generated by super typhoon Lupit (14–26 October 2009) over the western Pacific Ocean were detected by an on-land seismological array deployed in Northeastern China. We applied a frequency-domain beamforming method to investigate their source regions. Comparing with the best-track data and satellite obser...

In recent decades, various kinds of remote sensing-based drought indexes have been proposed and widely used in the field of drought monitoring. However, the drought-related software and platform development lag behind the theoretical research. The current drought monitoring systems focus mainly on information management and publishing, and cannot i...

In this work, the modulation of photoluminescence (PL) properties, which was realized by the composition and poling-induced structural evolution, for the Pr³⁺ doped (1-x)(Na1/2Bi1/2)TiO3-xBaTiO3 (NBT-xBT: Pr³⁺) piezoelectric ceramics was systematically investigated. Based on the Rietveld refinement structural analysis, there were two distinct compo...

In this study, Sm³⁺ doped Na0.5La0.5Bi8-xSmxTi7O27 (NBT-BITL-xSm, x = 0, 0.01, 0.015, 0.02, and 0.03) ceramics were synthesized via a conventional solid-state reaction process. The structural, electrical, and photoluminescence properties of NBT-BITL-xSm ceramics were systematically investigated. The crystal structure of NBT-BITL-xSm was refined usi...

Inter-growth bismuth layer-structured ferroelectrics (BLSFs), Bi4Ti3O12–Na0.5Bi4.5Ti4O15 (BIT–NBT), were successfully synthesized using the traditional solid-state reaction method. X-ray diffraction (XRD) Rietveld refinements were conducted using GSAS software. Good agreement and low residual are obtained. The XRD diffraction peaks can be well inde...

In this paper, Pr3+ doped Na0.25K0.25Bi2.5Nb2O9 (NKBN-xPr3+) ceramics were successfully prepared via a conventional solid-state reaction process. The structural, dielectric, and piezoelectric properties as well as photoluminescence performance of the samples were systemically studied. All the ceramic samples possessed a pure two-layered bismuth lay...

This study proposed a novel method to extract endmembers from hyperspectral image based on discrete firefly algorithm (EE-DFA). Endmembers are the input of many spectral unmixing algorithms. Hence, in this paper, endmember extraction from hyperspectral image is regarded as a combinational optimization problem to get best spectral unmixing results,...

This article proposes a post-disaster waterbody information extraction method based on spectral information from remote-sensing images and characteristic knowledge that can resist interference from factors such as changes in water quality, waves caused by accelerated water flow, and varying water levels. The method first analyses the display charac...

New lead-free inter-growth piezoelectric ceramics, Na0.5Bi8.5-xLaxTi7O27 (NBT-BIT-xLa, 0.00≤x≤1.00), were prepared by the conventional solid-state method. Structural and electrical properties of NBT-BIT-xLa were studied. All the NBT-BIT-xLa samples exhibited a single inter-growth structured phase. XRD and Raman spectroscopy revealed a reduced ortho...

Upconversion (UC) and electrical properties of Na0.5Bi8.5-xErxTi7O27 (NBT-BIT-xEr, 0.00⩽x⩽0.25) ceramics were studied. Structural analysis revealed that a single inter-growth structured phase exists in all samples and the Er³⁺ ion substituting for Bi³⁺ at the A-site increases the orthorhombic distortion. Under the 980 nm laser excitation, two chara...

Cross-sea bridges are typical target of natural sceneries. Extracting cross-sea bridges from remote sensing images appears significant. In this study, for the complexity of ground objects in GF-2 PMS satellite images, we have selected direction-augmented linear structuring elements to be used for extraction of cross-sea bridges. Firstly, pre-proces...

In this work, a novel lead-free multifunctional material, 0.94(Na1/2Bi1/2)TiO3-0.06BaTiO3-xSm³⁺(NBBT-xSm), was synthesized by a conventional solid-state reaction method. The crystal structure, electrical and photoluminescence properties of the samples were systematically investigated. It was found that doping Sm³⁺ into NBBT induced a transition fro...