水压环境下轴承支撑结构变形对其载荷分布的影响分析

当水下轴承支撑在工作过程中受到外力作用时,轴承的内圈或外圈会产生偏离理想圆形的变形,因而需要考虑变形后的形状来获得真实的载荷分布,或者把轴承套圈视为柔性。针对水下回转轴承内圈与其中空支撑轴结构采用固联装配的情况,分析了海水压力作用下中空支撑轴变形引起的轴承内圈变形,以及由此引起的轴承间隙变化,建立了轴承负荷与滚动体负荷的平衡方程,通过数值仿真计算,得到变形后轴承内圈的载荷分布。计算结果表明,在水下压力环境下轴承内圈变形后与变形前的载荷分布截然不同。轴承的力学性能下降,将会影响轴承的使用可靠性及寿命。

地下水库真实水压环境下坝体试件力学响应与破坏特征

地下水库坝体在水压环境下的稳定性是废弃矿井抽水蓄能电站长期安全运行的关键。针对地下水库真实水压环境,自主设计、研制伺服轴-水压联合试验装置,分析环境水影响方式,阐明轴-水压联合作用结构演化过程,判断坝体理论强度变化趋势,开展不同水压力环境坝体力学试验,确定水压对坝体试件力学性能影响规律,探讨细观断口形貌特征与宏观破坏形态。结果表明:真实水压环境对坝体试件产生水化学与水压力影响,涵盖7个方面的增强与弱化作用;试件水环境由外界围压水、贯通孔隙水、封闭孔隙水3个部分组成,在试件饱和及加载过程中水介质交互与裂纹扩展相互影响,水压力越大渗入量与影响越大;真实水压环境改变试件损伤量与有效孔隙,进而影响侧向有效应力与试件强度;随着真实水压环境的水压力增大,应力-应变曲线具有明显的屈服波动、强度先减小后增大、轴向应变则持续降低,试验机对试件的耗能逐渐减少,但耗散能占比增速加快;水压力增大后断口形貌处裂纹核数量减少,主裂纹依次为沿晶断裂-穿晶断裂-剪切破坏,细微裂纹数量增大,试件破坏形态经历张拉-张剪-剪切转变,且破坏愈加复杂,伴随崩脆声响。研究成果可提高地下水库监测评估准确性,并为废弃矿井抽水蓄能电站建设提供理论与试验依据。

舰船水压场频域检测的环境干扰特性分析

舰船水压场以其难于人工模拟性,被作为舰船的重要目标特性广泛应用于水中目标检测中,而对其进行频域检测又是最常用的舰船水压场信号检测方法。复杂多变的海洋环境中,诸多因素都对舰船水压场信号的频域检测性能产生显著影响,文章对在我国沿海不同海域获得的大量环境水压场数据进行分析,得到影响舰船水压场信号频域检测的主要因素,为水中目标探测器设计提供参考。

晶格应变理论及其应用

20世纪90年代Singh等人建立了基于非静水压缩的晶格应变理论。这一理论的建立使非静水压环境下状态方程的精确测量成为可能，同时也开辟了材料弹性常数测量的新方法。目前，这一理论在材料状态方程研究、强度研究、弹性研究和实验数据分析诸多领域有着广泛的应用。文中主要介绍晶格应变理论及其应用，并简要介绍我们利用晶格应变理论对高压下NiO弹性性质的研究结果。

高水压变化环境下鲫鱼的承受能力研究

以常见鱼种鲫鱼为研究对象,利用控制变量及统计分析方法开展鲫鱼在高水压条件下不同降压过程中承受能力的实验研究,分析了水压变化环境对鲫鱼的影响和不同大小的鲫鱼承压能力的差异。结果表明,压强和降压速率均对鲫鱼健康有重要影响,且两者关系密不可分。总体来讲,压强在3 MPa以内,鲫鱼均未受伤;压强在4~10 MPa范围内,压强和降压速率越大,鲫鱼受伤的几率越大;压强超过10 MPa后,鲫鱼会死亡,且压强越大,造成鲫鱼死亡的降压速率临界值越小。此外发现,鲫鱼对变压环境的承受能力似乎与其个体大小无明显的关系。该研究有望对未来高科技远洋渔业中所涉及的深水养殖及深水捕捞技术提供一定的理论依据和指导意义。

Input characteristics and risk analysis of ballast water from offshore entry ships in China

Large quantities of ballast water discharge from ocean going ships in sea ports of China is one of the important factorswhich cause the spread of aquatic nonindigenous harmful species isolated geographically by waters,the deteriorating environment of the near-shore water area and the frequent outbreaks of red tides.In this paper,the total amount of the ballast water input estimation model for entry ships in Chinese ports was established.The information of foreign trade shipping and the import and export goods released publicly by the State Department of Transportation and the State General Administration of Customs were investigated.And then,the input features and its ecological environment risk of ballast water in China's offshore entry ships from2007to2012were analyzed based on the established total input amounts of ballast water from entry ships to Chinese sea ports together with the ballast water input ratio of the five major port-groups in China.The results show that:the total ballast water input amounts from entry ships of the five major port-groups in China are extremely imbalanced.The most developed Yangtze River Delta in economy has the biggest total ballast water input amounts,103.61million tons in2012.The second is the Circum-Bohai Sea Region(73.66million tons)and the third is the Pearl River Delta(67.24million tons).The total ballast water input amounts of the northwest and the southwest coastal areas are less,only16.57and5.71million tons respectively.The large quantity of entry ships’ballast water discharge has been an enormous threat to ecological environment of our country's sea areas,especially to economically developed regions.

Tests to evaluate the ecological impact of treated ballast water on three Chinese marine species

Ballast water has been a topic of concern for some time because of its potential to introduce invasive species to new habitats. To comply with the International Convention for the Control and Management of Ships' Ballast Water and Sediments, members of the International Maritime Organization(IMO) must equip their ships with on-board treatment systems to eliminate organism release with ballast water. There are many challenges associated with the implementation of this IMO guideline, one of which is the selection of species for testing the ecological impacts of the treated ballast water. In the United States, ballast water toxicity test methods have been defined by the United States Environmental Protection Agency. However, the test methods had not been finalized in China until the toxicity test methods for ballast water were established in 2008. The Chinese methods have been based on species from three trophic levels: Skeletonema costatum, Neomysis awatschensis, and Ctenogobius gymnauchen. All three species live in broad estuarine and open sea areas of China; they are sensitive to reference toxicants and acclimatize easily to different conditions. In this paper, the biological characteristics, test processes and statistical analysis methods are presented for the three species. Results indicate that the methods for evaluating these three organisms can be included in the ecological toxicity tests for treated ballast water in China.

Hydrochemistry of the Natural Low p H Groundwater in the Coastal Aquifers near Beihai, China

Natural weak acidic groundwater occurs in the unconfined and confined aquifers consisting of Quaternary and Neogene unconsolidated sediments near Beihai in southern Guangxi, China. Under natural conditions the groundwater has low TDS(less than 200 mg L-1) and low concentrations of trace elements(less than 100 μg L-1) with a deceasing tend in contents of the Lanthanides(rare earth elements, less than 1 μg L-1) towards higher atomic number. The groundwater ranges in p H from 3.33 to 7.0 with an average value of 5.12(even lower than that of local rainwater, 5.88). p H values in the groundwater are a bit higher in rainy seasons than those in dry seasons and do not show significant increasing or decreasing trend with time. The average p H value in groundwater in the confined aquifers is even a bit lower than that in the unconfined aquifer. Comprehensive analyses of the groundwater environment suggest that H+ in the groundwater may be derived from dissociation of H2CO3, release of the absorbed H3O+ in clay layers and the acidity of rainwater. The H2CO3 in the groundwater may be formed by dissolution of CO2(g). Minerals in the unconsolidated sediment are predominated by quartz with small amount of clay minerals. The sediments undergoing a long-term weathering contain low levels of soluble constitutes. Lack of alkaline substances in the groundwater system is also helpful in the accumulation of acidity of the groundwater.

IMPACT EVALUATION OF HAIZUKA DAM ON ITS UP STREAM A CASE STUDY IN HIROSHIMA PREFECTURE, JAPAN

Japan ranks fifth in the world for the number of large dams. Environmental impacts of large dams are known, such as enormous losses of water or disruption of fish spawning, however, impacts of the dams on their up streams are functions of topography of the up stream. Haizuka Dam is located in Hiroshima Prefecture, Japan and its implementation will start in 2006. This large dam influences its up stream through dam making activities, which occurs in order and with different spatial presences that were categorized into chronological and spatial impacts. In this case study, spatial impacts were further divided into horizontal and vertical ones. The horizontal impacts were identified as new roads, diversion tunnel, dam lake, and submerged cultivated land, while vertical impacts were recognized as submerged historical monuments, slope protections, dam body, and deforested area in the reservoir. There were convergences of spatial and temporal impacts, however, the extent of the impacts was limited to the lake boundary.

Damage model of fresh concrete in sulphate environment

A model of damage to fresh concrete in a corrosive sulphate environment was formulated to investigate how and why the strength of corroded concrete changes over time. First, a corroded concrete block was divided into three regions: an expanded and dense region; a crack-development region; and a noncorroded region. Second, based on the thickness of the surface corrosion layer and the rate of loss of compressive strength of the corroding region, a computational model of the concrete blocks' corrosion-resistance coefficient of compressive strength in a sulphate environment was generated. Third, experimental tests of the corrosion of concrete were conducted by immersing specimens in a corrosive medium for 270 d. A comparison of the experimental results with the computational formulae shows that the calculation results and test results are in good agreement. A parameter analysis reveals that the corrosion reaction plays a major role in the corrosion of fresh concrete containing ordinary Portland cement,but the diffusion of the corrosion medium plays a major role in the corrosion of concrete mixtures containing fly ash and sulphate-resistant cement. Fresh concrete with a high water-to-cement ratio shows high performance during the whole experiment process whereas fresh concrete with a low water-to-cement ratio shows poor performance during the late experiment period.

Identification of Emergent Substances as an Indicator of the Presence of Microorganism in the Downstream of River Moraca in Locality-Vukovci

Based on the screening analysis for the first time in Montenegro, water samples for the presence of emergent wereanalyzed. Results from the locality Vukovci, the lower course of the river Morale, have shown the presence of chemical components that indicate the presence of emergent in the water. Thus identification component is associated with the presence of fiziological groups of microorganisms at the site, which with its functional and significant role in many ways reduce environmental stress.

Effect of pressure on the performance of plasma synthetic jet actuator

The effects of the ambient air pressure level on the performance of plasma synthetic jet actuator have been investigated through electrical and optical diagnostics.Pressures from 1 atm down to 0.1 atm were tested with a 10 Hz excitation.The discharge measurement demonstrates that there is a voltage range to make the actuator work reliably.Higher pressure level needs a higher breakdown voltage,and a higher discharge current and energy deposition are produced.But when the actuator works with the maximum breakdown voltage,the fraction of the initial capacitor energy delivered to the arc is almost invariable.This preliminary study also confirms the effectiveness of the plasma synthetic jet at low pressure.Indeed,the maximum velocities of the precursor shock and the plasma jet induced by the actuator with maximum breakdown voltage are independent of the ambient pressure level;reach about 530 and 460 m/s respectively.The mass flux of the plasma jet increases with ambient pressure increasing,but the strength of the precursor shock presents a local maximum at 0.6 atm.

A new sediment type of coated grain: Oolitic sinter

As a special sedimentary grain type, the coated grain(with an ooid model) has been known for two centuries due to its fascinating special fabric and genesis developments. The leading factors in forming the coated grain consist mainly of:(1) microorganism movement field;(2) chemical sedimentary effect;(3) hydrodynamic force environment and topography condition;(4) abundant core material supply;(5) embedding condition; and(6) humic acids condition in water medium. With the development of the coated grain genesis, the single factor theory cannot reasonably explain the exact formation of the surface sediment of coated grain. Here, we find a new way to study the coated grain on the basis of traditional research methods. The Wenquan area on the northeast edge of the Qiangtang Basin is one of the few areas where the coated grain is developing, and is a rare "natural laboratory" for the study of the coated grain and the thermal spring sediment. The oolitic sinter of the area has the triaxiality modality of pea polymer, and is obviously different from the karst travertine and the normal lacustrine ooid. We found that the hot spring water in the Wenquan area has higher partial pressure of CO2(PCO2) and saturation index of the calcite(SIc) than normal. Macrocosmically, the oolitic sinter is shaped like a pea, and its grains and gap fillings are light yellow. Microcosmically, the sinter grain forms six types of fundamental lamina, and those six types are developed to be four grain types with different combinations. The C-axis of the mineral grain of sinter cement(calcite) is normal to the lamina face, and grows on it with distinct generation formations. In short, the grain type of oolitic sinter is the oncoid, with the grain development caused by the factors such as the shallow water of strong hydrodynamic force, the special hydrochemistry condition, and the extensive algae activities(diatom).

An Range-free Localization Scheme for Large Scale Underwater Wireless Sensor Networks

In this paper, we study an area localization problem in large scale underwater wireless sensor networks （UWSNs）. The limited bandwidth, the severely impaired channel and the cost of underwater equipment all make the underwater localization problem very challenging. Exact localization is very difficult for UWSNs in deep underwater environment. We propose a range free method based on mobile detachable elevator transceiver （DET） and 3D multi-power area localization scheme （3D-MALS） to address the challenging problem. In the proposed scheme, the ideas of 2D multi-power area localization scheme （2D-ALS） and utilizing DET are used to achieve the simplicity, location accuracy, scalability and low cost performances. The DET can rise and get down to broadcast its position. And it is assumed that all the underwater nodes underwater have pressure sensors and know their z coordinates. We evaluate the performances of 2D-ALS and our proposed 3D-MALS schemes under both ideal and non-ideal channel propagation conditions, in terms of localization error and localization ratio. The simulation results show that our proposed scheme is much more efficient than the 2D-ALS.

Eco-engineering approaches for ocean negative carbon emission

The goal of achieving carbon neutrality in the next 30-40 years is approaching worldwide consensus and requires coordinated efforts to combat the increasing threat of climate change.Two main sets of actions have been proposed to address this grand goal.One is to reduce anthropogenic CO2emissions to the atmosphere,and the other is to increase carbon sinks or negative emissions,i.e.,removing CO2from the atmosphere.Here we advocate eco-engineering approaches for ocean negative carbon emission(ONCE),aiming to enhance carbon sinks in the marine environment.An international program is being established to promote coordinated efforts in developing ONCE-relevant strategies and methodologies,taking into consideration ecological/biogeochemical processes and mechanisms related to different forms of carbon(inorganic/organic,biotic/abiotic,particulate/dissolved) for sequestration.We focus on marine ecosystem-based approaches and pay special attention to mechanisms that require transformative research,including those elucidating interactions between the biological pump(BP),the microbial carbon pump(MCP),and microbially induced carbonate precipitation(MICP).Eutrophic estuaries,hypoxic and anoxic waters,coral reef ecosystems,as well as aquaculture areas are particularly considered in the context of efforts to increase their capacity as carbon sinks.ONCE approaches are thus expected to be beneficial for both carbon sequestration and alleviation of environmental stresses.