破损进水舰船非线性横摇运动的实验研究

通过设计破损舰船非线性横摇运动实验,对不同状态下的船模进行定频率变波高和定波高变频率的横摇激振试验,探讨舰船横摇运动的水动力特性随横摇频率和横摇幅角变化规律,分析Ⅱ类和Ⅲ类进水舱对破损舰船横摇运动的水动力特性的影响。运用混沌信号识别技术分析破损舰船进水后横摇运动的混沌特性,验证数值仿真的结果,预报破损舰船在规则波中的横摇运动的幅频响应和相频响应。     

具有淹水舱的舰船横摇运动建模探讨

舰船在风浪中横摇运动特性是影响舰船航行安全的主要因素,而当舰船由于碰撞、搁浅等意外事故造成船体破损进水后,具有淹水舱的舰船在风浪中的横摇运动将变得更加复杂,更加危险,文章系统地分析了具有淹水舱的舰船在波浪中横摇运动时船和舱内水的能量耦合作用,根据拉格朗日方程建立了具有淹水舱的舰船横摇运动两自由度微分方程,并在此基础上,用Melnikov方法对某实船破损进水后的横摇运动进行了非线性分析,验证了所建模型的实用性,为进一步分析破损进水舰船在风浪中的横摇运动特性提供了可行的数学模型.     

舱室进水情况下潜艇的挽回操纵

当潜艇由于各种意外事故造成艇体或通海管路破损进水后,具有淹水舱的潜艇在车、舵和高压气吹除作用下的挽回运动过程复杂而危险。文章借助Laval喷管理论建立了高压气吹除主压载水舱的模型,从而建立起包括舱室进水,用车用舵和舱室吹除等因素在内的,考虑了大攻角影响的潜艇挽回六自由度空间操纵运动模型。同时,针对不同进水部位、不同进水方式和不同航行深度等因素,计算得到了典型的潜艇水下操纵性安全界限图中的进水限制线。     

满液式蒸发器换热管布置的优化设计

在传统管壳式换热器结构设计的基础上,针对满液式蒸发器提出了一种换热管布置的优化设计方法,在结构型式不变的情况下,通过管排的优化设计,可以使管板上换热管的布置更加合理、紧凑,且能保证管排高度适中.该方法在提高满液式蒸发器换热能力的同时,还可有效减小其体积.     

Egg production of the copepod Acartia hongi in Kyeonggi Bay, Korea

Many studies of copepod egg production have shown that food availability and temperature are major factors that influence copepod growth. However, coastal environments are complicated ecosystem and the relationships between growth of copepods and influencing factors are not always clear in nature. We conducted a study along an inner–middle–outer bay transect where variations in environmental parameters would be expected to affect the biomass and egg production rate of A. hongi from February 2001 to December 2001. In this study, we investigated the abundance and biomass with developmental stages and egg production rates of A. hongi in relation to various environmental factors. The copepod A. hongi occurred continuously throughout the year, with a peak abundance in May. In general, the variation in egg production rates showed a similar tendency with the variations in chlorophyll-a throughout the study period. This suggests that phytoplankton biomass is an important factor that affects the egg production of A. hongi. In addition, during the warm season, the egg production of A. hongi was also influenced by the ciliates abundance in the middle and outer bay. Consequently, the egg production of A. hongi is generally affected by food availability in Kyeonggi Bay.     

Quantifying copepod kinematics in a laboratory turbulence apparatus

We describe application of a new apparatus that permits simultaneous detailed observations of plankton behavior and turbulent velocities. We are able to acquire 3D trajectories amenable to statistical analyses for comparisons of copepod responses to well-quantified turbulence intensities that match those found in the coastal ocean environment. The turbulence characteristics consist of nearly isotropic and homogeneous velocity fluctuation statistics in the observation region. In the apparatus, three species of copepods, Acartia hudsonica, Temora longicornis, and Calanus finmarchicus were exposed separately to stagnant water plus four sequentially increasing levels of turbulence intensity. Copepod kinematics were quantified via several measures, including transport speed, motility number, net-to-gross displacement ratio, number of escape events, and number of animals phototactically aggregating per minute. The results suggest that these copepods could control their position and movements at low turbulence intensity. At higher turbulence intensity, the copepods movement was dominated by the water motion, although species-specific modifications due to size and swimming mode of the copepod influenced the results. Several trends support a dome-shaped variation of copepod kinematics with increasing turbulence. These species-specific trends and threshold quantities provide a data set for future comparative analyses of copepod responses to turbulence of varying duration as well as intensity.     

工艺技术在修造船分段制作中的安全应用

修造船分段制作过程中的生产工艺是保证生产顺利进行,不发生安全事故的技术保障。文章从修造船小组立制作过程中最为重要的起重吊装和装配工艺技术两方面,举例介绍工艺技术在安全生产中的重要作用。     

船舶生产设计日程管理系统研究

船舶生产设计管理是一项复杂的系统工程,其中有大量复杂的数据和信息.文章分析了目前船舶设计的管理状况,从生产设计着手,重点介绍了一个日程管理系统的基本思路和功能,包括分析劳动负荷、分配任务、实时监控、人力资源优化配置和计划调整,使整个设计工作可以合理高效地完成.     

Plankton distribution and the impact of copepod grazing on primary production in Fram Strait, Greenland Sea

Two hydrobiological transects across the East Greenland Shelf and the open waters of Fram Strait in summer were chosen to illustrate the distribution and production of phyto- and zooplankton in relation to water masses and ice cover. The parameters used were temperature and salinity, inorganic nutrients, chlorophyll a, primary production, phytoplankton species composition, abundance of the dominant herbivorous copepods Calanus finmarchicus, C. glacialis, C. hyperboreus, Metridia longa and egg production of C. finmarchicus and C. glacialis. Grazing impact of copepodites and adults of these four species was modelled for each station by using egg production rates as an index of growth. Seasonal development of plankton communities was closely associated with the extent of the ice cover, hydrographic conditions and the water masses typical of the different hydrographic domains. Four regions were identified from their biological activities and physical environment: The Northeast Water polynya on the East Greenland Shelf, with a springbloom of diatoms and active reproduction of herbivorous copepods. The pack ice region, dominated by small flagellates and negligible grazing activities. The marginal ice zone, with high variability and strong gradients of autotroph production related to eddies and ice tongues, an active microbial loop and low egg production. The open water, with high station-to-station variability of most of the parameters, probably related to hydrographic mesoscale activities. Here, Phaeocystis pouchetii was a prominent species in the phytoplankton communities. Its presence may at least partly be responsible for the generally low egg production in the open waters. Grazing impact on primary production was always small, due to low zooplankton biomass in the polynya and due to low ingestion in the remaining regions.     

Host specificity in copepod parasites of deep-sea fishes

Parasitic copepods belonging to two orders, Siphonostomatoida and Poecilostomatoida, are frequently reported from fish hosts in the deep sea. Three families of copepods are most commonly encountered, Sphyriidae, Lernaeopodidae and Chondracanthidae, but members of another four families, Hatschekiidae, Pennellidae, Philichthyidae and Hyponeoidae, are occasionally recorded. These parasites utilise various deep demersal fishes as hosts, especially species of the most abundant families, Macrouridae, Moridae, Synaphobranchidae and Alepocephalidae. Host specificity levels are variable, as for shallow-water fishes. In contrast, few parasites are regularly reported from fishes inhabiting the pelagic water column away from the bottom and away from the near-surface zone. Only the pennellids Sarcotretes scopeli and Cardiodectes medusaeus appear common on pelagic fishes, in the Atlantic and Pacific respectively. Host specificity levels in these two pennellid species are relatively low. It is speculated that the difficulty of encountering a host in the vast pelagic biome has restricted the diversity of parasitic copepods that have successfully colonized pelagic fishes.     

The role of chemical signals in copepod reproduction

Because the reproductive fitness of a copepod is influenced by its ability to discriminate between conspecific and heterospecific mates, it is important to understand the mechanisms involved in these complex mate-recognition systems. Several lines of evidence suggest that chemical communication plays a role in mate location, recognition and reproduction in copepods. However, the relative importance of chemosensory cues, as well as other factors, including hydromechanical and morphological cues, remains unclear. Some studies show that mating ‘mistakes' occasionally occur in nature, which for species that mate only once, would have considerable effects on fitness. By reducing the likelihood of heterospecific matings, species-specific mate location and recognition chemicals have high adaptive value. The relative importance and molecular characteristics of these chemicals, whether diffusible or contact signals, may explain differences in premating and copulatory behavior observed among different copepod taxa. Current research suggests that both forms of chemical communication significantly influence the reproductive success of copepods. In this review, we summarize examples from the literature that may serve as a means to critically analyze postulated ideas and offer new questions for future study.     

The influence of different turbulence schemes on modelling primary production in a 1D coupled physical–biological model

A one-dimensional (1D) coupled physical–microbiological model has been applied to a site in the central North Sea. The impact of the choice of the turbulence closure scheme on the modelling the primary production has been investigated.The model was run with four different parameterisations of vertical mixing of heat, momentum and dissolved and suspended matters, using M2 tidal forcing and the hourly mean meteorological forcing of 1989 to reproduce the annual thermal structure and primary production. The four mixing parameterisations are: Level 2 turbulence closure scheme [Mellor, G.L., Yamada, T., 1974. A hierarchy of turbulence closure models for planetary boundary layers. J. Atmos. Sci. 31, 1791–1806; Mellor, G.L., Yamada, T., 1982. Development of a turbulence closure model for geophysical Fluid problems. Rev. Geophys. Space Phys. 20 (4) 851–875] using an explicit numerical scheme [Sharples, J., Tett, P., 1994. Modelling the effect of physical variability on the midwater chlorophyll maximum. J. Mar. Res. 52, 219–238]; a version of the Level 2.5 turbulence closure scheme [Galperin, B., Kantha, L.H., Hassid, S., Rosati, A., 1988. A quasi-equilibrium turbulent energy model for geophysical flows. J. Atmos. Sci. 45, 55–62; Ruddick, K.G., Deleersnijder, E., Luyten, P.J., Ozer, J., 1995. Haline stratification in the rhine/meuse freshwater plume: a 3D model sensitivity analysis. Cont. Shelf Res. 15 (13) 1597–1630] simplified to use an algebraic mixing length by Sharples and Simpson [Sharples, J., Simpson, J.H., 1995. Semidiurnal and longer period stability cycles in the Liverpool Bay region of freshwater influence. Cont. Shelf Res. 15, 295–313], also solved explicitly; the same simplified L2.5 scheme with an implicit numerical solution and modified vertical discretisation scheme [Annan, J.D., 1999. Numerical methods for the solution of the turbulence energy equations in the shelf seas. Int. J. Numer. Methods Fluids 29, 193–206]; and another version of the same scheme (but using a different algebraic mixing length) as described by Xing and Davies [Xing, J., Davies, A.M., 1996a. Application of turbulence energy models to the computation of tidal currents and mixing intensities in the shelf edge regions. J. Phys. Oceanogr. 26, 417–447; Xing, J., Davies, A.M., 1996b. Application of a range of turbulence models to the computation of tidal currents and mixing intensities in shelf edge regions. Cont. Shelf. Res. 16, 517–547; Xing, J., Davies, A.M., 1998. Application of a range of turbulence energy models to the computation of the internal tide. Int. J. Numer. Methods Fluids 26, 1055–1084]. Various model outputs at the sea surface and in depth profiles have been compared with data collected in 1989 as part of the North Sea Project [Huthnance, J.M., 1990. Progress on North Sea Project. NERC News, vol. 12, pp. 25–29, UK]. It is shown that the biological results are extremely sensitive to the small changes in the physical conditions, which arise due to the different turbulence schemes tested. The timing of the spring bloom and the maintenance of the midwater chlorophyll maximum all differ greatly between model runs, and the gross primary production varies by a factor of two from the highest to lowest results. The simplified Level 2.5 scheme, implemented using the numerical methods of Annan [Annan, J.D., 1999. Numerical methods for the solution of the turbulence energy equations in the shelf seas. Int. J. Numer. Methods Fluids 29, 193–206], produces results, which give the best agreement with the available data.     

MD-H2000码垛生产线的设计

简要介绍了MD-H2000码垛生产线及其工作原理,并阐述了码垛生产线的设计思想,采用的一些关键技术及其设计方法。     

Distribution of plankton lipids and their role in the biological transformation of Antarctic primary production

Production and transfer of lipid through the Antarctic food web is reviewed for the Indian Ocean sector. The slow settling fine particles showed a marked inter-annual variability in biochemical composition with an increase in lipid content as % organic carbon. Comparison of the fatty acid spectra of different size categories of organic particles indicated that fine particles are dominated by saturated, monoenoic and branched acids, while larger material (50–100 μm, 200–500 μm net collected fractions) displayed a signature dominated by polyunsaturated acids. Zooplankton taxa displayed different strategies of lipid accumulation. Lipid content was highest in Thysanoessa macrura females and copepodite stages of Calanus propinquus. Relatively low levels were recorded for juveniles and male stages of euphausiids. Reserve lipids varied with species: C. propinquus showed equal content of triglycerides and wax esters, T. macrura showed a dominance of wax esters and Euphausia superba and Themisto gaudichaudii accumulated only triglycerides. Computed as carbon equivalent and integrated over 200 m, lipids in slow settling particles represented 22.6% of annual primary production. Similar computation with mesozooplankton and E. superba data on biomass and population structure from several summer cruises indicated values of carbon accumulation as lipid reserves and egg production of 4.2 and 0.1% of annual primary production for copepods and 4.4 and 3.8% for E. superba. When all trophic levels are considered, the overall mean exceeded 30% of annual primary production.     

某艇海损修理生产设计概述

文章通过对某快速艇严重毁损成功修复的设计总结,简要介绍了在艇体遭受大面积毁损、变形严重情况下的修理过程控制要点,并针对施工工艺中出现问题的解决途径进行论述。就船厂而言,在原设计资料缺失的情况下,如何利用工厂自身条件合理制定出既切实可行、又能恢复设计性能指标,为部队、军代表所接受的修理方案,具有一定的实际意义。     

基于群体动力学的船舶企业安全生产培训模式

安全生产培训是改变员工安全生产意识的主要途径之一.如何高效地进行安全生产培训,是企业安全管理工作的一个重点攻克方向.船舶企业安全生产培训一直以来都受到以承包商职工为主体的一线员工自身特点的制约.文章用群体动力学相关理论作为指导,结合实际工作情况,设计并运行新型安全生产培训模式,进一步提高企业安全生产培训效率,增强了一线...     

Seasonal variability of fractionated phytoplankton, biomass and primary production in the Straits of Magellan

The results on the distribution of phytoplankton biomass (expressed as Chla) and primary production (¹⁴C assimilation), during three oceanographic cruises carried out during Austral spring and at the end of the summer and the autumn in the Straits of Magellan, suggest a strong variability of trophic levels for this ecosystem.Seasonal evolution of the biomass concentration goes from the spring maximum of 2.33 μg/l through a sharp decrease, 0.49 μg/l, observed at the end of summer, until the minimum of 0.24 μg/l measured during the autumn.The trophic conditions are dependent on hydrographic, meteo-climatic and geo-morphological characteristics: at the Atlantic entrance and between the two Angosturas the strong mixing of water column limit the development of phytoplankton; at the Western opening and along the Pacific arm the complex exchange mechanisms with the ocean, the glacio-fluvial contribution and the presence of a thermohaline front near the Isla Carlos III influence both biomass and primary production distributions. The maximum values are reached in the Central Zone (Paso Ancho) characterized by high stability of the water column.Primary production ranged from a minimum of 12.3 to a maximum of 125.9 mgC m⁻² h⁻¹. The overall trend seems to be a progressive and simultaneous increase from the Pacific and Atlantic openings to the Central Zone of Paso Ancho where the maximum value was reached. In general, biomass and primary production distributions correspond quite well except for the area of Isla Carlos III where biological and chemico-physical causes tend to limit ¹⁴C assimilation.Contribution of pico-phytoplankton (< 2 μm) to total biomass appears to be time dependent: in the blooms observed during spring a very modest incidence (< 6%) was observed whereas became more (> 50%) during the summer-autumn seasons when total biomass was decreasing.Within the Straits, at the end of summer, the contribution of pico-phytoplankton primary production is 59%, whereas nano and microplankton contribute 39% and 2%, respectively. At the oceanic external stations the photosynthetic activity of the bigger size-fraction (> 2 μm) is predominant (> 50%).These findings support the hypothesis that the pico-phytoplankton ( < 2 μm) is substantially constant, whereas temporal variations are due to the larger (> 10 μm) cells only.     

基于批量分割的虚拟单元制造系统多阶段动态调度

鉴于虚拟单元中批量分割调度模型研究的不足以及虚拟单元下批量分割呈现的新特点,文中考虑作业车间中同类设备有多台,多重作业具有不同加工路径可选的情况下的批量调度问题,其中批量分割包含横向分割和纵向分割。考虑到调度的复杂性,文中运用一个多阶段调度模型对设备资源进行分配,确定设备上的批量种类、大小和顺序,并在交货期内使总生产成本达到最小。通过算法对案例研究结果的对比,证明了所提方法的可行性和有效性。     

浮式钻井生产储卸装置运动性能分析

首先介绍了浮式钻井生产储卸装置(FDPSO)设有月池开口的船型特点,为评估月池开口对FDPSO船体运动性能的影响,设计了不同月池尺寸的方案。采用三维势流理论对不同月池尺寸方案水动力性能进行计算,得到FDPSO船体运动传递函数,总结FDPSO船体横摇和垂荡运动响应随月池尺寸变化的规律,并确定合理的目标FDPSO方案。最后对目标FDPSO方案进行运动性能实例分析,评估目标FDPSO方案的耐波性。     

鱼雷产品用电容器高温老化系统的故障分析

介绍了鱼雷产品用电容器高温老化系统在使用中所发生的各种常见故障,分析了这些故障对该系统主要技术参数的影响,以及解决这些故障的方法与措施,提出了对老化系统的维修与保养方法。