海水控制罗非鱼池塘中裸藻试验

用5‰、10‰、20‰及32‰4种盐度的海水,对罗非鱼池塘中的裸藻进行了杀灭试验。5‰盐度,64 8h以上可对裸藻的活动产生抑制作用;10‰盐度,72h可杀灭部分裸藻;32‰盐度,48h以上可完全杀灭裸藻。在罗非鱼养殖池塘中,控制裸藻宜用10‰盐度,处理时间55～146h。

基于改进BOA-PID的LT-MED系统冷凝器出口海水温度控制

针对低温多效蒸馏(LT-MED)海水淡化系统中冷凝器出口海水温度控制问题,在蝴蝶优化算法(BOA)的基础上,提出了一种改进BOA-PID控制方法,并利用MATLAB软件搭建仿真模型,将改进BOAPID控制的控制效果与BOA-PID控制、常规PID控制进行对比。结果表明,改进BOA-PID在适应度值和全局搜索能力方面表现卓越;与常规PID控制相比,基于改进BOA-PID控制系统中相应的优化程序能够自动整定各个参数,提升了系统的响应速度,大幅减小了超调量,提升了海水淡化系统的造水比,系统能正常运行。

王滩电厂海水淡化电气和热控系统安装技术

通过河北大唐王滩电厂海水淡化工程,介绍了电气系统及海水淡化控制系统关键工序的施工安排、主要的施工方案及调试方案,对于今后同行业的施工具有重要的指导意义。

河蟹亲蟹培育技术要点

0引言 河蟹人工工厂化培育已经过二十年的发展,其技术水平和生产能力都达到了一个较高的层次,成为一个规模较大的产业.目前河蟹苗的产销趋于平衡,价格也处在一个较合理的市场化水平.然而暴利遮盖问题的年代已不复存在,某些关节上出现问题,就会使育苗业效益产生较大的波动,因此河蟹育苗业是目前水产业一个风险较大的产业.近十年来河蟹育苗在温度控制、饵料利用和疾病防治方面都取得了较大的突破,但在亲蟹培育方面还存在许多问题,如亲蟹死亡严重、掉卵、死卵、出现花卵等现象,严重影响了河蟹育苗业的发展,对相当一部分育苗场来说亲蟹培育的好坏已成为河蟹苗种生产的瓶颈.

摩西拯救威尼斯 意大利27亿美元启动“世纪工程”

意大利总理西尔维奥·贝卢斯科尼和威尼斯市长保拉·科斯塔2003年5月14日参加了“摩西工程”的奠基仪式，意大利政府的举动使得这个拖延了30年之久的工程终于宣告启动——“摩西工程”将由三个浮动水坝组成，分别建造在威尼斯城和亚得里亚海交汇的海水入口处。每个水坝坝体有78个“挡板”，每个“挡板”宽20米，长30米，重达300吨，当涨潮的时候，可以通过压缩空气泵控制其竖起或者放平，从而控制进入威尼斯的海水水量。美国《时代》周刊称，这是威尼斯700年来最接近于最终解决水患问题的一次。

The REMO Ocean Data Assimilation System into HYCOM(RODAS_H):General Description and Preliminary Results

The first version of the Brazilian Oceano- graphic Modeling and Observation Network （REMO） ocean data assimilation system into the Hybrid Coordi- nate Ocean Model （HYCOM） （RODAS H） has recently been constructed for research and operational purposes. The system is based on a multivariate Ensemble Optimal Interpolation （EnOI） scheme and considers the high fre- quency variability of the model error co-variance matrix. The EnOl can assimilate sea surface temperature （SST）, satellite along-track and gridded sea level anomalies （SLA）, and vertical profiles of temperature （T） and salinity （S） from Argo. The first observing system experiment was carried out over the Atlantic Ocean （78°S-50°N, 100°W-20°E） with HYCOM forced with atmospheric reanalysis from 1 January to 30 June 2010. Five integra- tions were performed, including the control run without assimilation. In the other four, different observations were assimilated： SST only （A SST）; Argo T-S profiles only （AArgo）; along-track SLA only （A_SLA）; and all data employed in the previous runs （A_All）. The A_SST, A_Argo, and A_SLA runs were very effective in improv- ing the representation of the assimilated variables, but they had relatively little impact on the variables that were not assimilated. In particular, only the assimilation of S was able to reduce the deviation of S with respect to ob- servations. Overall, the A_All run produced a good analy- sis by reducing the deviation of SST, T, and S with respect to the control run by 39%, 18%, and 30%, respectively, and by increasing the correlation of SLA by 81%.

Preparation of polysaccharides in different molecular weights from Ulva pertusa Kjellm (Chorophyta)

As molecular weight controls the biological activities of polysaccharides, screening the optimal molecular weight of polysaccharides is important in drug research and application. In this study, hydrogen peroxide was employed as oxidant, and temperature, reaction time, and concentration of polysaccharides and hydrogen peroxide were examined for their effects on the preparation of polysaccharides in different molecular weights from Ulva pertusa. Our experiment suggested that the optimal degradation concentrations for polysac-charides and hydrogen peroxide were 2.5% (w/v) and 8.0% (v/v), respectively. The range of degradation measured by relative viscosity was mainly controlled by temperature and time. Results revealed that 35℃ was the optimal temperature for obtaining low-degradation samples, and 50℃ was the most favorable temperature to accelerate the reaction to yield highly-degraded samples. Four samples in different molecular weights A, B, C and D were finally prepared. The controllability was evaluated by the relative standard deviation (RSD) of relative viscosity, and the peak molecular weights and the polydispersity indexes (Mw/Mn) of molecular weights were measured by high performance gel permeation chromatography (HPGPC).

Nonlinear trajectory tracking control of a new autonomous underwater vehicle in complex sea conditions

Autonomous underwater vehicles (AUVs) navigating in complex sea conditions usually require a strong control system to keep the fastness and stability. The nonlinear trajectory tracking control system of a new AUV in complex sea conditions was presented. According to the theory of submarines,the six-DOF kinematic and dynamic models were decomposed into two mutually non-coupled vertical and horizontal plane subsystems. Then,different sliding mode control algorithms were used to study the trajectory tracking control. Because the yaw angle and yaw angle rate rather than the displacement of the new AUV can be measured directly on the horizontal plane,the sliding mode control algorithm combining cross track error method and line of sight method was used to fulfill its high-precision trajectory tracking control in the complex sea conditions. As the vertical displacement of the new AUV can be measured,in order to achieve the tracking of time-varying depth signal,a stable sliding mode controller was designed based on the single-input multi-state system,which took into account the characteristic of the hydroplane and the amplitude and rate constraints of the hydroplane angle. Moreover,the application of dynamic boundary layer can improve the robustness and control accuracy of the system. The computational results show that the designed sliding mode control systems of the horizontal and vertical planes can ensure the trajectory tracking performance and accuracy of the new AUV in complex sea conditions. The impacts of currents and waves on the sliding mode controller of the new AUV were analyzed qualitatively and quantitatively by comparing the trajectory tracking performance of the new AUV in different sea conditions,which provides an effective theoretical guidance and technical support for the control system design of the new AUV in real complex environment.

Seismic geomorphology and main controls of deep-water gravity flow sedimentary process on the slope of the northern South China Sea

The Quaternary continental slope of the Baiyun Sag in northern South China Sea is characterized by a complex topography and abundant gravity flow sedimentation.High-resolution 3-D seismic data in this area allow for a detailed study of the seismic geomorphology and deep-water gravity flow depositional process.The Quaternary continental slope in the northern South China Sea is an above-graded slope.An intraslope basin lies within the above-grade continental slope.Slump,erosion,and deposition processes tend to develop a gentle topography and consequently a graded slope.The upper continental slope,which is above the slope equilibrium profile,is dominated by erosion and slumping.Slides,slumps and erosional channels are developed within this continental slope.The intraslope basin is located below the slope equilibrium profile and is potential accommodation space where sediments transported by gravity flows could be deposited,forming lobe aprons.Under the influence of gravity flow supply,gravity flow duration,continental slope topography,equilibrium profile,and accommodation,a slump-erosional channel-lobe depositional system is developed in the Quaternary continental slope in the Baiyun Sag.The deep-water gravity flow depositional process and the distribution of gravity flow sediments are greatly influenced by the continental slope topography,while the continental slope topography at the same time is reshaped by deep-water gravity flow depositional process and its products.The study of the interplay between the continental slope and gravity flow is helpful in predicting the distribution of the deep-water gravity flow sediments and the variation of sediment quality.

Controlling factors for gas hydrate occurrence in Shenhu area on the northern slope of the South China Sea

Temperature and pressure on seafloor of the northern slope in the South China Sea are suitable for gas hydrate formation, but bottom simulation reflector (BSR), an indication of gas hydrate occurrence, only occurred in limited areas of the slope. Drillings in the BSR-distributed area (the District S) on the northern slope of the South China Sea suggested that gas hydrate only occurred at Sites SH2, SH3, and SH7 with high saturation (up to 20%-40%), and there is no hydrate at Sites SH1 and SH5 although the distance between SH1 to SH3 is only 500m. In this paper, we investigated seafloor gradient, fault development, temperature, and pressure in the District S on the northern slope of the South China Sea to understand the possible factors con- trolling BSR distribution and gas hydrate occurrence. The District S is a structurally fractured continental slope zone and its seafloor gradient varied greatly. The BSR-occurred areas have an average gradient of 19.89×10 2 whereas the BSR-free zone has the average gradient of 10.57×10 2 . The calculated relative structural intensities from fault densities and displacements show that the BSR-distributed areas tend to occur in the areas with a moderately high structural intensity, where faults frequently developed close to the seafloor that are possibly favored for lateral migration of gases. On the basis of temperatures and pressures at drilling sites, hydrate-occurred Sites SH2, SH3, and SH7 are located within the thermodynamically stable area for methane hydrate, and hydrate-absent Sites SH1 and SH5 are out of the thermodynamically stable area for methane hydrate formation, suggesting that both BSR and the thermodynamic stability are necessary for hydrate occurrence in the subsurface.

A long-term in situ calibration system for chemistry analysis of seawater

An in situ calibration system is a versatile exploration instrument for electrochemical sensors investigating the biochemical properties of the marine environment. The purpose of this paper is to describe the design of an auto-calibrating system for electrochemical (pH) sensors, which permits two-point in situ calibration, suitable for long-term measurement in deep sea aqueous environments. Holding multiple sensors, the instrument is designed to perform long-term measurements and in situ calibrations at abyssal depth (up to 4000 m). The instrument is composed of a compact fluid control system which is pressure-equilibrated and designed for deep-sea operation. In situ calibration capability plays a key role in the quality and reproducibility of the data. This paper focuses on methods for extending the lifetime of the instrument, considering the fluidics design, mechanical design, and low-power consumption of the electronics controller. The instrument can last 46 d under normal operating conditions, fulfilling the need for long-term operation. Data concerning pH measured during the KNOX18RR cruise (Mid-Atlantic Ridge, July-August, 2008) illustrate the desirable properties of the instrument. Combined with different electrodes (pH, H2, H2S, etc.), it should be of great utility for the study of deep ocean environments, including water column and diffuse-flow hydrothermal fluids.