Complicated Environmental Conditions Research Articles

出入港操船の安全性評価に関する研究 : 台湾における操船シミュレータ実験の経験

The state of the art in ship handling simulator applications for manoeuvring safety studies in Taiwan is reviewed and a procedure is proposed for real-time simulation based on the concept of elemental manoeuvres and the development of a manoeuvring plan. Case studies of methods of evaluating manoeuvring difficulties and its safety are described. The results are as follows: (a) Although it is difficult to determine the critical value of indices showing the difficulty of each manoeuvre under complicated environmental conditions, a practical solution is to evaluate the difficulty by taking into account the subjective opinion of the ship handlers together with the objective indices studies. (b) To have a more objective evaluation of manoeuvring safety in a port, it is recommended that assessments of difficulty and safety are carried out.

Interactive 3-D canonical acoustic modeling

There is often the question of whether the behavior of acoustic signals can be predicted in the complex and changing ocean environment. Our deplorable state of prediction is either blamed on limitations of acoustic models, or on the usually incomplete knowledge of the ocean environment, or on both. Despite the fact that efforts are being made to provide the critical links between the fields of oceanography and acoustics, still lacking is a comprehensive strategy to measure or predict oceanic features in order to improve our acoustical predicting capability. In a companion paper, a generalized canonical sound-speed (GENCASS) numerical environmental model is discussed. This GENCASS model is implemented in the Pesogen computer system [J. Acoust. Soc. Am. Suppl. 1 75, S26 (1984)] for illustration of the feasibility of using such a technique in an interactive acoustic modeling machine to better understand the interrelationships between complicated environmental conditions and their acoustical consequences. The interactive nature of this process allows rapid understanding of the database requirements, in preparation for setting environmental knowledge bounds toward better predicting capability. Examples will be shown to demonstrate the realistic nature of the canonical oceans.

Population identification of red-fin pargo,Parargyrops edita Tanaka, in Taiwan strait and Beibu Gulf

This paper deals with population identification ofParargyrops edita Tanaka. Samples of spawning stocks were collected from Niushan-Penghu, Minnan-Taiwan shoal (Southern Fujian-Taiwan shoal) and Beibu Gulf during the spawning period 1981–1982. Morphological characters, both meristic and morphometric, are counted and measured respectively. The stock concept and intraspecific categories have been discussed. Some meristic characters as the number of left or right ventral fin spine, right ventral fin rays and abdominal vertebrae of this fish may be constant, others as the numbers of left or right pectoral fin rays and gill-rakers may have obvious geographical variation. Morphological characters have not attained the level of subspecific distinctness, no sub-species could be found among these stocks by means of coefficient of difference (C.D.). Basing upon the comparative analysis ofMdiff, the authors consider that stocks of Minnan-Taiwan shoal and Niushan-Penghu belong to the same local population, Taiwan Strait local population. By means of the discriminant function analysis and linear relationship analysis, statistical differences will be found to exist in meristic characters between the stock of Minnan-Taiwan shoal and that of Niushan-Penghu, so that the two are virtually different stocks or subpopulations. The stock of Beibu Gulf belongs to another called the Beibu Gulf local population. These two local populations are of allopatric distribution and show statistically significant difference between themselves. Among these stocks, the Minnan-Taiwan shoal stock is strongly influenced by the much more complicated environmental conditions of the mixed boundary region of the subtropical Sino-Japanese Subregion in the north and the tropical Indo-Malayan Subregion in the south. Thus its coefficient of variability (C.V.) is greater than those of the other two in the mean values of various meristic characters.