Ocean data buoys are a critical means of automatically acquiring offshore oceanographic and meteorological data, offering advantages of long-term, fixed-position, continuous, and real-time monitoring. The turbulence generated by the buoy’s structure is a significant factor affecting wind speed measurement accuracy. In this study, a 10 m-diameter buoy was analyzed to evaluate the influence of structural turbulence and shielding effects on wind speed measurements. The Reynolds-averaged Navier-Stokes (RANS) equations, combined with the RNG k–ε turbulence model, were employed to simulate the flow field and turbulence characteristics. Numerical simulations were conducted to calculate wind fields around the buoy and measured wind speeds at two sensor heights with varying pitch angles. The shielding effects on wind measurements were examined across different wind directions. To assess the impact of photovoltaic panels, wind fields and wind speed measurements were also analyzed for a configuration without these panels. Results indicate that shielding effects can cause substantial wind speed measurement errors, particularly when sensors are located on the leeward side, due to the formation of low -wind -speed zones in the wake region. Measurement error increases with higher incident wind speeds. Sensors positioned at greater elevations exhibit improved accuracy, as they are less affected by near-surface turbulence. Removing photovoltaic panels reduces measurement error; however, the shielding effects caused by the buoy body itself remain significant and cannot be neglected.

In recent years, with the development of technologies such as the Internet of Things (IoT), big data and cloud computing, digital twin technology has gradually been applied in marine research. The digital twin realizes real-time monitoring, analysis and optimization of the state and behavior of a physical object or system by creating a virtual model. Research shows that digital twin technology has extensive application potential in ship design, marine resource development, marine equipment engineering design and optimization, marine ecological protection and early warning of disasters. Although digital twin technology has great potential in marine research, it also faces many challenges, including the complexity of data acquisition and processing, the accuracy and real-time performance of model construction, and the need for multidisciplinary cross-integration. An in-depth analysis of the technical bottlenecks and future development directions will provide an important reference for subsequent research and promote the further application and development of digital twin technology in marine research.

Through active manipulation of wavelengths, a structure exposed to a water-wave field can achieve a target hydrodynamic performance. Based on the form invariance of the governing equation for shallow water waves, wavelength modulators have been proposed using the space transformation method, which enables wavelength manipulation by distributing an anisotropic medium that incorporates water depth and gravitational acceleration within the modulation space. First, annular wavelength modulators were designed using the space transformation method to reduce or amplify the wavelength of shallow water waves. The control method of wavelength scaling ratios was investigated. In addition to plane waves, the wavelength modulator was applied to manipulate the wavelength of cylindrical waves. Furthermore, the interactions between a vertical cylinder and modulated water waves were studied. Results indicate that the wavelength can be arbitrarily reduced or amplified by adjusting the dimensional parameters of the modulator. Additionally, the modulator is effective for plane waves and cylindrical waves. This wavelength modulator can enable the structure to achieve the desired scattering characteristics at the target wavelength.

Ocean data buoys are among the most effective tools for monitoring marine environments. However, their measurement accuracy is affected by the motion of the buoys, making the hydrodynamic characteristics of buoys a critical issue. This study uses computational fluid dynamics to evaluate the motion performance of large ocean buoys under wave loads with different characteristics. A high-fidelity numerical wave tank was established via the overset mesh method and the volume of fluid method to simulate wave‒structure interactions. The results indicate that the buoy motion is influenced primarily by the first-order harmonic components of the waves. The response amplitude operators (RAOs) for both surge and heave gradually approach a value of 1 as the wave period increases. The pitch RAO peaks at the natural frequency of 2.84 s. As the wave steepness increases, the nonlinearity of wave‒structure interactions becomes more pronounced, resulting in 13.78% and 13.65% increases in the RAO for heave and pitch, respectively. Additionally, the dynamic response under irregular waves was numerically simulated via full-scale field data. Good agreement was obtained compared with field data.

In this work, we present a high-quality (Q) dual-resonance sensor based on all-dielectric metasurface for refractive index and temperature sensing simultaneously. The all-dielectric metasurface was composed of a periodic array of Si nanocluster placed on the commercially available glass substrate. Two distinct optical resonance modes with extremely high Q factors of 13500 and 14900, a magnetic quadrupole mode (MQ), and toroidal dipole mode (TD), are observed at 1614.12 nm, and 1639.02 nm in the reflection spectra, and confirmed by the electromagnetic field distribution of each resonance. To further reveal the underlying coupling effects of the two resonances, we also perform a systematic analysis of the influence of the differences in radius (Delta R) and gap (Delta x and Delta y). At last, the refractive index and temperature sensing performance were investigated. More specifically, the proposed sensor exhibits a maximum refractive index sensitivity of 418 nm/RIU for the analyte refractive index range between 1.33 and 1.37, and maximum temperature sensitivity of 86.4 pm/degrees C in the range of 0 degrees C-40 degrees C, which demonstrates great linear relationship and is much better than the previous sensors based on all-dielectric structure. The proposed all-dielectric metasurface is an effective way to achieve refractive index and temperature dual-parameter sensing, which will facilitate wide applications in unstable environment, such as the measurement of temperature and salinity in seawater.

Fiber Bragg grating (FBG) has been widely used in many fields for the measurement of temperature, strain, and other parameters, but single-mode FBG has across-sensitivity problem between temperature and strain. In this article, a new scheme is proposed to solve the problem by using parallel core-cladding FBGs, whose grating areas are located at the interface region of the core and cladding of the fiber. The sensing principle of parallel core-cladding FBGs for the simultaneous measurement of temperature and strain is theoretically analyzed. The femtosecond laser point-by-point method of the parallel core-cladding FBGs is experimentally investigated. Two parallel FBGs, namely, core FBG and cladding FBG, are formed efficiently and conveniently by a single time inscription. Two transmission peak shave been observed, which are excited by the core mode and the cladding mode. The experiment results demonstrated that the proposed compact sensor can detect the temperature with sensitivity of 11.043 pm/C-degrees and strain with sensitivity of 1.2101 pm/mu epsilon up to 1.114 x103 mu epsilon, and the relative errors of temperature and strain are less than 5.8% and 8.3%,respectively. The proposed parallel core-cladding FBGs are much more compact as one FBG element compared with the conventional structure with two cascaded FBGs or parallel FBGs. The parallel core-cladding FBGs can overcome the cross-sensitivity problem of single-mode FBG, which has great application value and potential in fiber sensing fields for dual-parameter

A polarization-maintaining fiber Bragg grating (PM-FBG) is a crucial component of fiber optic sensors, and the inscription method associated with it has garnered significant interest. Compared to alternative technologies, the femtosecond laser point-by-point inscription method offers greater flexibility. However, it is still unclear how the controllable factors of the femtosecond laser point-by-point inscription process relate to the spectral characteristics of PM-FBG. The main factors that affect the spectral properties of PM-FBG inscribed via the femtosecond laser point-by-point method, including the pulse energy, grating length, fiber type, and grating apodization, are investigated experimentally and theoretically in this paper. An experimental investigation was conducted to examine the relationship between the pulse energy and side lobe suppression ratio (SLSR), and the optimal pulse energy was approximately 30 nJ to obtain the highest SLSR. The theoretical model of the full width at half maximum (FWHM) is presented, and it is shown that the FWHM tends to saturate with grating lengths greater than 8 mm. There is a linear relationship between the distance of the two reflection peaks and the birefringence of the polarization-maintaining fiber (PMF), regardless of the birefringence induced by the inscription process. The oblique apodization method can decrease the SLSR of the two reflection peaks, but it also broadens their FWHM. This study provides compelling evidence to support the improvement in the spectral performance of PM-FBGs inscribed via the point-by-point femtosecond laser inscription method.

海洋资料浮标在海洋环境监测、预警预报、防灾减灾、资源开发、海上交通、渔业生产、军事活动保障等方面具有重要作用,是海洋立体监测体系的重要组成部分.世界主要沿海国家和国际组织都极为重视海洋浮标技术的发展.海上观测过程中,浮标随风、浪、流等作用产生复杂运动.浮标复杂运动的精确观测离不开浮标姿态信息测量技术的发展.浮标姿态信息,不仅是浮标及其搭载设备工作安全性可靠性评价的重要参考,也是浮标测量数据实时精准校正的重要保障.因此,浮标姿态测量技术具有重要的研究价值和应用价值.文章从工程实际的技术需求出发,对浮标姿态信息测量技术的研究现状、技术难点以及发展趋势等方面进行了梳理和总结,以期对研发新一代智能浮标观测技术提供有益启发和借鉴.

Marine monitoring instruments and equipments are crucial for understanding and managing the ocean. In recent years, significant achievements have been obtained in the technologies and application of marine monitoring instruments and equipments in China. However, China still lags behind developed countries in terms of core technologies and equipment for marine monitoring. This study analyzes the development requirements and development status of China’s marine monitoring instruments and equipment from the aspects of global ocean stereoscopic observation system, national nearshore operational observation system, and technologies and core equipment for marine environment monitoring and detection. Moreover, it elaborates on the problems existing in China’s marine monitoring instruments and equipment in terms of policies and mechanisms, original innovation and basic scientific research, common key technologies, technical standards and testing, as well as cincization and industrialization. Furthermore, we propose key development directions and several suggestions including (1) establishing an innovative system of marine monitoring instruments, (2) expanding the marine monitoring instrument industry, and (3) building a marine public test infrastructure, hoping to provide a reference for the development and research of China’s operational marine stereoscopic monitoring system.

海洋是人类生存发展的新疆域,也是各国竞相角逐的制高点.海洋强国,装备先行.海洋环境监测是关心海洋、认识海洋、经略海洋的基础,对我国海洋强国战略顺利实施具有重大意义.海洋监测浮标是今后相当长时期内我国获取海洋战略安全数据、实现离岸海洋综合环境参数长期连续现场实时观测必不可少的支柱装备,也是挺进深海、大洋、两极等国家战略新高地的"先锋队"和"排头兵".

海洋资料浮标是离岸原位获取水文、气象等环境参数的重要技术手段,在海洋环境实况监测、预警预报、防灾减灾、资源开发、海上交通等方面具有重要作用.本文概述了海洋资料浮标的作用、组成、分类、主要理论及技术体系,总结了近年来国内海洋资料浮标的发展历程和技术突破,介绍了我国目前海洋浮标监测网的构成、应用情况,并与国际先进国家的浮标进行了比较.最后,展望了海洋资料浮标及监测网技术未来的发展趋势.

Marine data buoy can provide a long-term, continuous, real-time, reliable data of ocean observation in a variety of complex marine environment. It is one of the most reliable, most effective and important means of ocean monitoring technology. In this paper, the classification, main theory and technology system of marine data buoy are summarized. The typical technological breakthrough of the development of marine data buoy in recent years is summarized. The composition and application of marine monitoring network in China was introduced, and the gap between the technology of China's marine data buoy and the international advanced countries is compared. Combined on the situation and demand of China's current situation and needs, the development trend of marine data buoy and buoy monitoring network are expected.

In order to solve detection of multi-user detection in underwater acoustic communication networks, blind adaptive multiuser detection method using LMS algorithm was proposed to solve the MAI problem of multi-user detection in underwater acoustic communication channel when users increase. Two type simulations were executed, including synchronous and asynchronous multi-user simulation analysis, to verify the validity of LMS multi-user detection algorithm and inspection machine. The verification of the effectiveness of the MMSE and MOE algorithm for LMS multi-user detection algorithm was done by simulation.

In order to solve multi access interference (MAI) effect of multi-user blind detection in underwater acoustic communication networks, blind adaptive multi-user detection method based on improved Kalman filter algorithm was proposed. This method can suppress the MAI problem when the user number increases. Simulation was done for both traditional Kalman method and improved Kalman method in synchronous and asynchronous multi-user communication case, the differences of detection character between the two methods were examined, and the validity of improved Kalman blind detection algorithm in multi-user underwater acoustic communication is proved.

<正>海洋装备的技术水平和规模,是衡量一个国家综合实力和现代化程度的重要标志之一——二十一世纪是海洋的世纪。海洋是国土、是资源、是通道,是新的生产和生活空间。海洋装备是指与蓝色经济有关的各类海洋仪器设备。包括海洋动力环境监测设备、海洋生化环境监测设备、海洋生物资源调查设备、海洋灾害预报预警系统设

AGV(Automatic Guided Vehicle) is widely used in manufacturing factories, harbors, docks and logistics fields, because of its accurate automatic tracking. An AGV tracking method of detecting trace color based on RGB color sensor is provided here. D R , D G , D B values of trace color are obtained by color sensor, with which hue value denoting trace color characteristic can be calculated. Combined with graph theory algorithm, hue value can be used as a parameter for tracking deviation and branch identification to implement shortest path tracking. In addition, considering discreteness and uncertainty of single sensor in detecting trace information, sensor array is adopted for information fusion to achieve accurate tracking. Compared to tracking trace by single intensity sensor, AGV tracking based on RGB color sensor array has much better trace tracking and branch identification performances on complex roads.

The subject shows a kind of system for collecting the data of wind speed and wind direction data, called wireless wind speed collecting system. It expounds the main method of design, the principle of operation, the process of designing the hardware and the software. The system used a kind of wind speed and wind direction sensor made in USA, it can collect the data for a period of time that needed, it has automatic memory recording function. At last, it delivers the data to the accepting station usually stated at bank by the VHF communication machine.

A self-study type vehicle autonomous navigation method using GPS receiver is introduced. In this method, the position information received by GPS receiver is linear processed through regression algorithm, and track information is divided into sections based on linear correlation coefficients, then the linear correlated sectioned beeline information is compressed and recorded to form the track information of autonomous navigation. In navigation process, the moving direction of the track can be predicted by calculating the vector angle and judging the vector direction from the sectioned beeline information, and the autonomous navigation is realized. The autonomous navigation track information obtained by the proposed method features high navigation accuracy and direction prediction capability.

In order to improve the detection range and sensitivity of the sensor, the basic design method of a high sensitivity pyroelectric infrared sensor is presented. This sensor adopts a sine-wave current generator and a magnetic coil to produce electromagnetic force that drives the convex lens to swing slightly. The detected pyroelectric infrared signal passes through an optical filter and is focused by the swinging convex lens and the infrared focus is also swinging slightly. So, the pyroelectric sensor that is located on the moving track of the infrared focus is scanned by the infrared focus signal continuously and generates the autonomous sampling pyroelectric signal. Because the convex lens has a large photic area, which allows a lot of infrared rays to be focused, the detection sensitivity of the sensor is improved. Generally, for the same sensing elements, the detection range of the autonomous sampling pyroelectric infrared sensor is three times the detection range of Fresnel-lens sensor.

The development situation of marine monitoring technology and instrument industry of China is summerized in this paper.The necessity and importance of establishing and developing the marine environmental monitoring system are presented.Some problems that must be soloved in this field are analyzed from two respects such as monitoring system(construction) and the development of marine instruments.