Analysis of the parasitic copepod species richness among Mediterranean fish

The Mediterranean ichthyofauna is composed of 652 species belonging to 405 genera and 117 families. Among these, 182 were studied for their parasitic copepods. The analysis of all the works conducted on these crustacea yielded 226 species distributed in 88 genera and 20 families. For each fish species we have established a file providing the species name of the fish, its family, its geographical distribution within the Mediterranean and some of its bio-ecological characteristics. Within each file, all the parasitic copepod species reported on each host species were listed. This allowed to know the species richness (SR) of these hosts. We thus produced 182 files within which 226 copepod species are distributed. A program was created under the Hypercard software, in order to analyse our data. Two parameters were studied. The first one is the mean species richness (MSR), which corresponds to the mean of the different SR found on the different host species. The second is the parasite–host ratio (P/H), which is the ratio of the number of copepod species by the number of host species. These parameters are calculated by our program for all the 182 species of Mediterranean fishes retained in our investigation, on the first hand, and, on the second hand, for one particular group of fish species. We used the following variables to investigate their correlations with copepod species richness: taxonomy—fish families, genera and species; biometry—maximal size of the adult fish; eco-ethology—mode of life (benthic, pelagic or nectonic), displacements (sedentary, migratory with environmental change, or migratory without environmental change), behaviour (solitary or gregarious). Other variables (colour, food, reproduction, abundance, distribution area) were also analysed but did not reveal any clear correlation. Providing that our study does not rely on quantitative (prevalence, intensity) but qualitative basis our aim was only to reveal some tendencies. These tendencies are as follows: (1) In many cases, parasite and host phylogeny seem to play an important role. There are fish families with copepods and families with few species of these parasites. The phyletic constraints could be due to the morphological characteristics of the habitat (e.g. structure of the gills) or biological/ecological characteristics that we were unable to identify. (2) It appears that the presence in a same environment of related fish species (e.g. several species of the same genus, or numerous genera of the same family) is correlated with high parasite richness. A likely explanation is that such situations favours alternated processes of lateral transfers and speciation. (3) Some eco-ethological criteria seem to favour the establishment of a large parasite species richness. It should be noted for instance that Mediterranean fishes the most often infected with copepods are generally nectonic or pelagic, migratory, and gregarious species.     

YK型油轮应急拖带装置的设计研究

介绍ＹＫ型油轮应急拖带装置的设计研制过程。根据国际海事组织（ＩＭＯ）１９９４年通过的ＭＳＣ．３５（６３）决议“关于油轮应急拖带装置的指南”的要求，确定了装置的组成部件、技术参数和型号规格；对收缆绞车进行传动计算和强度验算；对强力端结构及焊缝进行强度校核；并确定了船首部和尾部甲板的加固方案。船尾部应急拖带装置中的强力端及导缆座是关键的受力部件，是专门设计的。对该部件的强度和稳定性用结构分析程序ＳＡＰ５进行了有限元计算，结果表明，该设计是可靠的。为使装置能适应多种形式规格液货船的需要，在研制中采用较高的设计标准和Ｂ级优质钢板。除保证钢材在成份和机械性能上的要求外，还对钢材的低温冷脆性能作了补充检测。为确保制作工艺质量，装置的焊缝经过磁粉探伤和超声探伤检验。     

可编程控制器在船舶辅助锅炉中的应用

应用PLC控制器的特点,设计了适用于船舶锅炉控制的PLC控制工作时序、I/O分配、控制程序,通过模拟试验,设计的软件程序能达到系统的工作要求,证明利用PLC控制极大地提高了锅炉工作的可靠性及自动化水平。     

船用增压锅炉烟气净化器实验系统及分析方法

通过对增压锅炉净化器净化机理和特性分析,构建了气固两相流动实验系统,选取树脂、EPS聚苯乙烯球、小米等3种固体颗粒作为实验材料,对某型船用增压锅炉烟气净化器样品和新研制产品在不同运行工况下的净化效率及阻力特性进行了系统的模拟实验研究,着重介绍其实验系统及分析方法。     

双相不锈钢在化学品船建造中的应用

介绍了化学品船建造中首次采用双相不锈钢中防止板材损伤和污染,以及焊接以后不锈钢表面处理的技术措施,保证装焊的合格率在98%以上,达到较高的质量标准。     

吊舱式电力推进装置的首次成功应用

全回转舵桨合一、吊舱式电力推进装置是新颖的船舶动力装置.结合我国首艘成功采用吊舱式电力推进装置船舶的实施效果,较详尽地介绍了电力推进技术的先进性能.     

改进的BP神经网络方法在舰船修理费用预测中的应用

文章基于神经网络理论,以某型舰船特装修理费用为例,建立了改进算法的BP神经网络预测模型,最后对海军舰船特装修理费用进行了中短期预测。     

伺服缸型电-气式主机遥控装置研究

伺服缸型电-气式主机遥控装置，其调速(调速器)控制部分运用微计算机“PID”编程控制技术，调速输出信号经“D／A”、“E／P”转换为标准气压信号，由调速器执行器即伺服气缸比例输出，对主柴油机进行转速、负荷控制。在我国以“V390”系列主柴油机为主动力装置的高速船舶数船队中，船舶主机遥控毫无例外地都应用了伺服缸型电-气式主机遥控装置。     

对某机车厂引进柴油机机体加工系统的经济评价

本文利用现值原理和投资回收理论,计算了不同方案的长期差量成本现值的差异及差量成本当年的差异.有效地解决了某厂引进设备的经济可行性问题.文中构造的评价模型具有一定的普遍意义.     

集装箱船的大型化开发及其引发的问题

首先概要介绍近年来世界集装箱船大型化的发展，接着分析指出，远洋运输成本低廉是集装箱船大型化发展的驱动力，然后提出大型化发展中出现的3个问题值得讨论。第一个问题是大型化发展受港口航道水深、码头装卸机械等条件制约。第二个问题是设计制造超大型集装箱船的主机不易。最后一个问题是，为解决超大型集装箱船的巨量货物的“集疏运”，必须开发电子信息技术。作者最后提出，21世纪初对大型集装箱船的箱量定位应为8000标准箱。