Showing papers by "Ocean University of China published in 2001"

Studies on the nutrition of the large yellow croaker, Pseudosciaena crocea R. I: growth response to graded levels of dietary protein and lipid

Abstract: The suitable protein-to-lipid ratio for juvenile large yellow croaker, Pseudosciaena crocea Richardson (initial body weight, 0.57 ± 0.11 g) was determined using practical diets in a 4 × 3 factorial experiment. Four dietary protein levels (34%, 37%, 42% and 47%) and three dietary lipid levels (7.5%, 10.5% and 14.0%) were tested. Each of the 12 diets was fed to triplicate groups of croaker juveniles for 60 days in floating netcages (1.0 × 1.0 × 2.0 m3) in the sea. The effects of dietary treatments on survival, weight gain, feed conversion ratio, protein efficiency ratio, hepatosomatic index and carcass composition of the fish were evaluated. At all three lipid levels, the best growth was always obtained in the fish fed diets of 47% protein. At 34% protein, better growth was observed for the fish fed the diet with 10.5% lipid, whereas at the protein levels above 37% the diets containing 10.5% and/or 14.0% lipid proved better. Based on the results of current experiment, the dietary protein:lipid ratio of 47:10.5 appeared to be suitable for this fish. Feed conversion ratio ranged from 1.40 to 1.98, declining with the increases of both dietary protein and lipid. The carcass lipid was correlated positively to dietary lipid, unlike the carcass protein that was independent of dietary protein. There was no interaction between dietary protein and lipid except for carcass lipid. Further investigations should be conducted to determine the optimal protein-to-lipid ratio for large yellow croaker juveniles using diets containing higher levels of protein and lipid than 47% and 14%, respectively.

Pseudo almost periodic solutions for the systems of differential equations with piecewise constant argument [ t + 1/2]

Abstract: In this paper we investigate the existence and uniqueness of pseudo almost periodic solutions and unboundedness of other solutions for the systems of differential equations with piecewise constant argument [t + 1/2] by means of new notion of pseudo almost periodic vector sequences. The case in which the characteristic equation has multiple roots is considered.

Cloud detection using probabilistic neural networks

Abstract: This paper investigates the application of a particular type of probabilistic neural networks, namely radial basis function (RBF) networks, to detecting cloud in NOAA/AVHRR images. Based on the images collected from the East China Sea, the paper compares the performance of RBF networks with that of traditional multi-layer perceptrons (MLPs). The main results show that RBF networks are able to handle complex atmospheric and oceanographic phenomena while MLPs could not. The internal representation of the RBF networks and MLPs are also detailed in this paper.

A new two-stage scoring normalization approach to speaker verification

Abstract: In speaker verification, the cohort and world models have been separately used for scoring normalization. The authors embed the two models in elliptical basis function networks and propose a two-stage decision procedure for improving verification performance. The procedure begins with normalization of an utterance by a world model. If the difference between the resulting score and a world threshold is sufficiently large, the claimant is accepted or rejected immediately. Otherwise, the score will be normalized by a cohort model, and the resulting score will be compared with a cohort threshold to make a final accept/reject decision. Experimental evaluations based on the YOHO corpus suggest that the two-stage method achieves a lower error rate as compared to the case where only one background model is used.

A new mangrove-dwelling nemertean from China

Abstract: Nemertean specimens were collected from the mangrove zone in the estuary of Jiulong Jiang River. Histological studies revealed that they belong to genus Pantinonemertes but differed from the known taxa of the genus. In the present paper they are described as a new species, Pantinonemertes fujianensis sp. nov. The immature specimens, with the body rounded anteriorly and somewhat dorso-ventrally flattened in intestinal region, measured about 85–120 mm long and 1.5–2.0 mm wide. Dark pigment is concentrated along the mid-dorsal line to form a longitudinal stripe that extends for most of the body length. The head possesses a pair of horizontal longitudinal furrows, a pair of oblique lateral furrows and four eyes. A precerebral septum is absent. The proboscis is well developed and possesses 19 large proboscis nerves. The frontal organ is a well-developed tubular structure, with the epithelium regionally differentiated. Cephalic glands are extensive, consisting of faintly stained small glands that open into the frontal organ, large blocks of clear gland and orange-staining glands (stained with Mallory triple method) that open through the ducts penetrating the body wall. The excretory system consists of numerous binucleate flame cells especially in the anterior body region, each flame cell possesses 7–9 transverse cuticular support rings. Excretory tubules either open to exterior via the efferent ducts penetrating the body wall or open into the frontal organ. Lateral nerve cords are without accessory lateral nerves.

Application of MLP and RBF networks to cloud detection

Abstract: The paper compares the performances of multilayer perceptrons (MLPs) and radial basis function (RBF) networks in detecting clouds in NOAA/AVHRR images. The main results show that the RBF networks are able to handle complex atmospheric and oceanographic phenomena while conventional rule-based systems and MLPs cannot. In particular, the experimental evaluations show that the RBF networks can converge to global minima while the MLPs can only achieve this occasionally, and that classification errors made by the RBF networks decrease dramatically when the number of basis functions increases. In addition, these errors are almost identical when the number of basis functions reaches a threshold. Only on a few rare occasions does the backpropagation algorithm attain an optimal solution and the classification errors made by the MLPs are comparable to (but still larger than) the ones made by the RBF networks. However, the results show that achieving such optimal solutions is difficult. It is, therefore, concluded that the RBF networks are better than the MLPs for cloud detection.

Dissolved and particulate organic carbon in yantai sishili bay aquiculture waters

Abstract: Investigation of dissolved organic carbon (DOC) and particulate organic carbon (POC) at 12 stations in Yantai Sishili Bay in May, August, and November of 1997 and March and May of 1998 showed that DOC concentrations varied from 1.14mg/L to 5.35mg/L; that the average values at all stations in each cruise varied from 1.52mg/L to 2.12mg/L; that POC concentrations varied from 0.049mg/L to 1.411 mg/L; and averaged 0.159mg/L to 0.631mg/L in each cruise. Horizontal distribution of DOC was influenced by factors such as continental input, organism activity, temperature, aquiculture environment, etc. The higher POC concentration occurred along the coast. The vertical distribution of DOC and POC changed obviously in spring and summer, but not obviously in autumn and winter. DOC concentration was highest in summer and POC in spring; both were lowest in winter. The seasonal change of DOC was consistent with primary productivity seasonal variation, and that of POC was consistent with chlorophyll-a seasonal variation. The seasonal change trend of the C/N ratio of dissolved organic matter was obvious, but the C/N ratio of particulate organic matter had no such trend.

Carbon isotope geochemistry in the Yalujiang estuary

Abstract: The distribution of particulate organic carbon (POC) along the lower reaches is similar between the dry season and the flood season in the Yalujiang Estuary, North China. However, the values of particulate organic carbon of the upperstream in the dry season are one magnitude lower than the concentrations in the flood season. Stable carbon isotope ratios have been used to study the sources of particulate organic carbon in the Yalujiang Estuary. The isotopic composition of POC shows a range from −23.1% to −29.4% with a little seasonal variation. The isotopic evidence indicates that the POC in the Yalujiang Estuary is predominantly of terrestrial origin rather than a result ofin situ plankton. The study of the ratio of POC: Chla shows that the turbidity maximum plays an important role in POC cycle in the Yalujiang Estuary. Organic detritus and soil erosion are the main contributions to POC in the turbidity maximum, especially in the flood season.

A study on the baroclinic structure of the abyssal circulation

Abstract: In this paper, the linear continuously tratified model of the abyssal circulation proposed by Pedlosky (1992) was extended to include the second order term -(γθzzz) in the vertical turbulent mixing parameterization of\( - \overline {(w\prime \theta \prime )} _z = k_u \theta _{zz} - \gamma \theta _{zzz} \), in whichkv is a vertical diffusion coefficient, and γ is the second order coefficient of turbulent mixing (or simply called γ-term and γ<0 is only allowed). The influence of the γ-term on the baroclinic structure of the abyssal circulation driven by upwelling out of the abyss was investigated. It was found that the γ-term has a noticeable influence on the baroclinic structure of the upwelling driven abyssal circulation. For uniform upwelling, it favors the baroclinic layering of the abyssal circulation in the eastern part of the basin, but prevents the layering in the west. In addition, this parameter was found to decrease the vertically averaging meridional velocity of the abyssal circulation from the west to the east on the southern boundary. For upwelling localized near the eastern boundary, the γ-term favors baroclinic layering of the abyssal circulation in the whole basin. Especially, on the southern boundary the γ-term could strengthen the vertically averaging meridional velocity in the west, but greatly weaken it in the east. The model presented here might be considered as an extension of the Pedlosky baroclinic model of the abyssal circulation.