渔船主机前端输出离合器的选用

主机轴输出端离合器作为海洋渔船的必备装备，近年来得到了较大的发展，目前主要有圆锥摩擦式离合器、电磁离合器、液压离合器和气胎离合器等几种型式，如何合理地选用、将直接影响渔船的经济效益以及船员的人身安全。本文拟对这些问题邓以探讨。     

统一我国渔船主机离合器的设想

一、渔船主机离合器必须统一。目前我国250匹马力到600马力的渔船所采用的离合器种类繁多，使用和维修极为困难。来我厂大修的渔船，其主机离合器就有胀瓦式、干片式，也有L2齿箱离合器。而且同一形式的也与上海的不一样，就得去外地找图纸、购零件，还要定做工夹具。这些辅助工作往往都是单件配做。既延长了修船周期，又增加了修理费用，修理质量难以保证。可见，采用统一型的渔船主机离合器是多么重要。     

电磁离合器在渔船机械中的应用

一、概述。渔船上使用的离合器，大多采用摩擦式离合器。其结构型式分为片式摩擦离合器、圆锥摩擦离合器、胀式离合器以及具有高弹性的锥体与气胎式离合器。离合器主动部分与从动部分的结合是依靠机械力、液压力或气动力实现的。依靠机械力的，难于进行远距离操纵，更不能实现集中与自动控制。对于液压与气动的，虽然可以远距离控制．但机件的精密度高，结构与管路、阀件较复杂，维护保养技术较困难，特别是气动的体积较大．采用以电磁离合器为主要元件的远距离自动控制装置，能够较好地克服上述技术困难。     

CQL气胎离合器

目前，我国渔船主机前端装置普遍采用摩擦离合器驱动甲板渔捞机械。由于该离合器是刚性连接，安装时，轴线对准要求高，在使用中又往往存在较大的机械振动，接合不稳定，严重时甚至会发生断轴等现象。我公司借鉴日本尾滑道渔轮主机前端输出与甲板液压渔捞机械配套的先进设备及技术，结合国内渔轮的工况及现有工艺条件，在1982年试制成功CQL-600型(原称DFA-1型)气眙离合器，于1983年8月接受浙江省渔船联合设计室的委托，     

全回转拖轮中的OMEGA离合器

我厂建造的2600PS全回转拖轮，使用日本新泻铁工所生产的OMEGA离合器。全回转拖轮舵桨系统（ZP）与Z形中间轴及OMEGA离合器联接的动力装置在拖轮、工程船上有很多好处。特别是OMEGA离合器的无级调速作用、使船舶的操作性能大有改观。OMEGA离合器grl置的定距桨、其船舶机动性及可操作性可与可调桨媲美。在价格和维修的简便性比可调桨略胜一筹。IOMEGA离合器的结构与原理11结构（见图1）就是赋予滑动控制结构的湿式多板离合器。其特点是利用滑动控制，能够输出柴油机最低稳定转速以下的转速，并能任意调节输出轴的转速作用。本离…     

对19.95米玻璃钢渔船轮机设计的几点浅见

19.95米 F·R·P 竿钓渔船,是我国目前最大的玻璃钢渔船。本文仅从轮机部分的设计、提高航速及螺旋浆轴系的尾管结构等提出了点改进的意见,以便共同探讨.     

我国渔船小型液压舵机合理型式的探讨

一、前言。我国木质渔船目前正在陆续更新，这批船大多是机帆渔船，大部分是用链条式机械传动的人力舵机，推舵力矩在200-1000公斤·米左右。在实现四个现代化的八十年代，新的钢质渔船应采用什么样的舵机，值得考虑。     

文登市造船厂在改革中迈大步

山东文登市造船厂是以造船为主、多业并举的综合性企业,拥有固定资产837万元,下设埠口船厂、长会口船厂、轧钢厂和塑料彩印厂四个生产单位。今年以来,他们采取一系列行之有效的措施,使企业在前两年跳跃发展的基础上再迈大步。1—2月份,完成产值425.7万元,销售收入411.3万元,形成利润65.7万元,分别比上年同期增长了59％、278％和577％。 一、加快技改步伐,不断扩大生产能力。多年的生产实践使该厂的干部职工深刻认识到,只有不断强化技改措施,加快技改步伐,保持产品的先进性,才能赢得企业的生存与发展。他们坚持开发一代、研制一代、贮备一代的方针,积极开发应用新技术、新成果。先后多次对渔船推进器、导流管、离合器等关键部位进行技术改造,大大提高了渔船性能,仅对离合器改造一项,就可使渔船拖力提高半吨。针对保鲜运输发展迅速、远洋作业渔船越来越多的实际,他们大     

渔船轮机基本知识问答(二)

问:渔船动力装置有何特殊要求? 答:渔船在海上进行渔捞作业时间较长,环境艰险,经常要在火风浪中作业,纵横摇晃情况严重、负荷瞬时变化大。对拖网渔船除了自由航行外。大部分时间在拖网作业。使主机长时间作低转速高负荷运转,在起网过程中倒顺车变化频繁,据统计鲔延绳钓渔船作业时,主机离合器每天离合次数常在1000次以上,这使柴油机负荷经常处于剧变状况。由渔汛和作业要求动力机动性要高。此外一般渔船的机舱容积比较狭小,机舱温度较高。中小型渔船要求柴油机自由端也能输出功率,以传动液压油泵和起网机等渔捞机械。为此总的要求:渔船动力机械设备坚固耐用,安全可靠,管理维修方便,重量轻,体积小,机动性     

浅谈渔船柴油机的运行管理

<正> 渔业现代化的重要标志之一,是广泛采用先进的渔业机械、仪器装备渔船。每艘渔船除安装一台主机外,还配置若干台辅机,主机的功率一般大于辅机功率的数倍。特殊用途的作业渔船,也有安装2台主机的。 根据我国渔船作业航区的划分,基本上分为三类:Ⅰ类航区——无限航区;Ⅱ类航区——距岸120～200海里的海区;Ⅲ类航区——距岸10～20海里的海区。衡量我国渔船的大小习惯上用马力统计,一般200马力(147kW)以上称为渔轮,185马力(136kW)以下称为小型渔船,规定小型渔船在近海Ⅲ类航区和部分Ⅱ类航区作业。 由于目前渔船作业海区外延,航程远,对主机的安全运行提出了更高的要求,其中至关重要的是要加强渔船柴油机的运行管理。根据以往的经验和事故的教训,可归纳为以下五个方面: 1.柴油机起动前的准备工作 打开冷却水阀门,检查海水冷却系统主机柜的水是否充足;检查柴油日用柜内是否有足够的柴油,放掉沉淀物和残水,打开油阀和润滑油阀门,检查油位是否达到要求;检查蓄电池容量和压缩空气压力是否足够起动;检查离合器和转车装置是否脱开;检查轴系刹车有无障碍物,排除气缸内的残油、残水。 2.起动时及起动后应注意事项 电力起动每次按起动电纽不超过10s,间隔1min;起动气泵时要检查冷泵压力,要求一次起动成功,随即关闭?     

Reproductive life history of the North American madtom catfish, Noturus hildebrandi (Bailey & Taylor 1950), with a review of data for the genus

Abstract– The female reproductive traits of a small, North American catfish were studied over a two-year period in a population at the southern extreme of the species'range. The reproductive season was long for Noturus , possibly from February to September. Females matured at age 1 and probably reproduced in only a single year. Clutch sizes were 16–68 oocytes in females 33–47 mm SL, and only one lifetime clutch may be produced. Clutch size, dry mass and volume were related to female size, but ripening oocyte size was not. Clutch mass averaged 23% of total body mass just prior to spawning. Compared to a northern population, females had greater SL-adjusted body masses, clutch sizes and clutch volumes but smaller oocytes. Oocyte size accounted for 73% of the difference in clutch sizes and clutch volume 14%. Concerns about the comparability of present data for Noturus are expressed. The need to include many life-history traits, from several populations of each species, using standardized methods in analysis of functional responses is discussed.     

Development and growth heterogeneity in oriental river prawn, Macrobrachium nipponense (De Haan) (Palaemonidea), in onthogenesis

Abstract. At all onthogenesis stages of the Oriental river prawn. Macrobrachium nipponense (De Haan), size heterogeneity has been traced within one egg clutch, at different developmental stages of larvae, young and adult individuals. The problem of predetermining heterogeneity is discussed. Uneven larval development of individuals from a single clutch is shown. Also, it is shown that the first to become adults are the individuals hatched from small eggs. Conclusion is made that in estimating development and growth heterogeneity the genetic factor has a primary nature. Available data accounting is essential for selective culturing of prawns under controlled conditions with the required growth characteristics.     

Effects of plant oligosaccharides derived from dragon fruit on growth,reproduction and survival of freshwater crustacean Daphnia magna

The freshwater crustacean Daphnia is widely used as live food for ornamental fish. To increase production, food supplementations are required when culturing Daphnia. Here, we aimed to clarify the effects of plant oligosaccharides derived from dragon fruit (DFO) on growth rate, egg production, number of first clutch juveniles and survival of Daphnia supplemented with five different concentrations of DFO, that is 0, 1, 3, 9, 27 mg/L. The results showed the growth and reproduction of Daphnia were enhanced when supplemented with DFO. Growth rate of Daphnia supplemented with 9 mg/L DFO was the highest among all treatments. The time that Daphnia produced the first clutch eggs was shorter in high concentration of DFO (3, 9, 27 mg/L). The number of juveniles in the first clutch increased in treatments of higher concentration of DFO (3, 9, 27 mg/L). These results suggest that plant oligosaccharides derived from dragon fruit increase growth and fecundity of Daphnia. Survival rates of Daphnia were 100% except for the treatment supplemented with 27 mg/L of DFO in which the survival rate was reduced to 87%. To our knowledge, this is the first functional evidence demonstrating that oligosaccharides derived from dragon fruit enhance growth and fecundity of Daphnia.     

Population viability and perturbation analyses to support recovery of imperilled Eastern Sand Darter (Ammocrypta pellucida)

Small‐bodied freshwater fishes are often understudied, with the result that data gaps create uncertainties that can complicate and constrain conservation strategies aimed at species recovery. Use of matrix models and perturbation population viability analyses (PVA) are ideally suited for use in studying the consequences of life‐history parameter variation and environmental stochasticity to better understand the fate of threatened small‐bodied fishes. We use data for Eastern Sand Darter (Ammocrypta pellucida) populations from the Thames River, Canada, to explore the consequences of life‐history uncertainties such as age at maturation, multiple clutch sizes and age‐specific fertility for population recovery in this species. Environmental stochasticity acting on all life‐history parameters was found to pose significant risks for the continued viability of lower Thames River populations, with significant chances of local extinction predicted under current conditions. The intrinsic rate of population increase was most sensitive to 0+ survival rates, clutch size and clutch number. As demonstrated here, population models can successfully provide a means of exploring the population dynamics of small‐bodied fishes and can inform managers of risks posed by factors acting on life‐history parameters to affect continued population viability. Management actions for Eastern Sand Darter should focus on strategies designed to ensure successful spawning and improvement of 0+ survival rates, through programmes aimed at the protection, enhancement or recovery of additional spawning and juvenile rearing habitats.     

Seasonal and interannual components of intrapopulation variation in clutch size and egg size of a darter

Abstract –  Previous studies have offered suggestive but sometimes conflicting glimpses at the range and patterns of seasonal and interannual variation in female darter life-history traits. The present study examined clutch-size and egg-size variation from a single Mississippi population of brighteye darters (Etheostoma lynceum ), collected at regular intervals over four sequential spawning seasons. Both life-history traits were significantly correlated with body size, and they both showed significant variation within and among breeding seasons. The overall intraseasonal trends in these traits involved an increase in clutch size (CS) and a decrease in egg size from early to late periods of the spawning season. Clutch size and egg size showed a weak but significant negative correlation, which was indicative of a trade-off between the two clutch parameters. Seasonal changes in temperature appear to be related to differing patterns of seasonal variation in egg size reported in the literature for darters. Inverse seasonal shifts in egg size and CS in the brighteye darter may represent adaptive phenotypic plasticity that allows females to produce larger, competitively superior offspring early in the reproductive season when there is low supply of food for them (parental investment hypothesis) or to produce larger eggs early in the reproductive season to ensure that each egg is adequately provisioned in the face of uncertainty (bet-hedging hypothesis) if the food available for the young is unpredictable early in the season. Consistent with theoretical predictions, egg size showed less phenotypic variability than CS.     

Phenotypic plasticity for life history traits in a stream population of the threespine stickleback, Gasterosteus aculeatus L.

Abstract – The life history traits of breeding size, clutch size, egg size and relative clutch mass were examined for evidence of plasticity within a set of six annual samples of threespine stickleback, Gasterosteus aculeatus L., females from south-central Alaska, USA. Three samples (from 1992, 1996 and 1999) were of stickleback native to, and living within, a stream environment, while three (from 1995, 1996 and 1999) represented fish living within a pond environment recently colonized by the stream stickleback. Significant differences between stream and pond fish were found for all four traits. For most traits, pond-living females showed greater variation both across and within years than did stream-living females. Although extremely rapid evolution within the pond, or genetic drift caused by low founding population size, could not be completely ruled out, trait changes across years in both environments were interpreted as representing adaptive plasticity.     

Egg collection from hatchery-reared broodstock of spotted halibut Verasper variegatus treated with LHRH analog

The objective of this study is to establish a method for acquiring large quantities of high-quality eggs for artificial fertilization from hatchery-reared broodstock of spotted halibut Verasper variegatus. We estimated the optimum conditions for implantation of luteinizing hormone-releasing hormone analog (LHRHa) cholesterol pellet (LHRHa-CP) to induce ovulation from two experiments which focused on the dose and the timing combined with monitoring of oocyte development by ovarian cannulation. From the results of cannulation, vitellogenesis of hatchery-reared broodstock was suggested to occur normally, although final oocyte maturation was not initiated in the first clutch of oocytes. In late December, oocytes in the most advanced clutch still underwent vitellogenesis, having diameter of about 0.82?mm. LHRHa-CP implantation during this period had no remarkable effects, except for administration at high dose (100???g/kg). In contrast, in mid January, when oocyte diameter reached about 0.95?mm, ovulation occurred in most individuals, even at low dose (20???g/kg). In mid February atretic oocytes became remarkable and LHRHa-CP implantation showed much lower performance in terms of egg quality. The diameter of growing oocytes converged to about 0.95?mm, which was that of fully grown postvitellogenic oocytes. Thus, oocyte diameter is suggested to be an effective indicator to estimate the timing of LHRHa-CP implantation.     

Parasitism, water temperature and life history characteristics of the freshwater fish Gobiomorphus breviceps Stokell (Eleotridae)

Abstract – Life history traits can vary among populations of the same fish species in response to selective pressures exerted by the local environment. Here we used inter-population comparisons to investigate the effects of parasitism and variability in water temperature on life history traits in a New Zealand freshwater fish, the upland bully. Although age and size at maturity varied among populations, they were not significantly related to either temperature regime or average parasite load. Trade-offs between egg size and clutch size were only apparent in one of the seven populations when populations were analyzed separately but became clear when all data were pooled. However, neither average population clutch size or egg size was related to the population's mean parasite load or the local temperature regime. Although the latter two parameters may influence other life history variables, such as the number of clutches produced per season and the partitioning of eggs among clutches, there was no evidence that they influenced life history strategies of the upland bully populations investigated here. ^Note     

Reproductive biology of white mullet,Mugil curema (Valenciennes) in the Southern Caribbean

Gonadal development and spawning of white mullet, Mugil curema in the Gulf of Paria, Trinidad, West Indies, was investigated using both macroscopic and histological techniques. M. curema is a multiple batch spawner with a protracted spawning season from November to July. Gonadal development is annual and each female appears to spawn at least twice per year. The prolonged spawning season may thus be an indication of the lack of population synchrony rather than prolonged spawning by a single individual. Peak-spawning activity occurs in June/July and it is hypothesized that it is in response to the start of the rainy season. Oocyte development is group synchronous and development of oocytes in the leading clutch is isochronal.