Investigation of air-core vortex at hydraulic intakes

Hydrodynamic properties of the surface vortex have been investigated. Based on the Navier-Stokes equations, three sets of the new formulations for the tangential velocity distributions are derived, and verified against the experimental measurements in the literature. It is shown that one modification greatly improves the agreement with the experimental data. Physical model experiments were carried out to study the intake vortex related to the Xiluodu hydropower project. The velocity fields were measured using the Particle Tracking Velocimetry (PTV) technique. The proposed equation for tangential velocity distribution is applied to the Xiluodu project with the solid boundary being considered by the method of images. Good agreement has been observed between the formula prediction and the experimental observation. © 2010 Publishing House for Journal of Hydrodynamics.

High frequency multimode radiation from ducts with flow

Multimode sound radiation from hard-walled semi-infinite ducts with uniform subsonic flow is investigated theoretically. An analytic expression, valid in the high frequency limit, is derived for the multimode directivity function in the forward arc for a general family of mode distribution functions. The multimode directivity depends on the amplitude and directivity function of each individual mode. The amplitude of each mode is expressed as a function of cut-off ratio for a uniform distribution of incoherent monopoles, a uniform distribution of incoherent axial dipoles and for equal power per mode. The modes' directivity functions are obtained analytically by applying a Lorentz transformation to the zero flow solution. The analytic formula for the multimode directivity with flow is derived assuming total transmission of power at the open-end of the duct. This formula is compared to the exact numerical result for an unflanged duct, computed utilizing a Wiener-Hopf solution. The agreement is shown to be excellent. Copyright © 2008 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Comparison between empirical formulae of intake vortices

The hydrodynamic properties of free surface vortices at hydraulic intakes were investigated. Based on the axisymmetric Navier-Stokes equations and empirical assumptions, two sets of formulations for the velocity distributions and the free surface profiles are proposed and validated against measurements available in the literature. Compared with previous formulae, the modifications based on Mih's formula are found to greatly improve the agreement with the experimental data. Physical model tests were also conducted to study the intake vortex of the Xiluodu hydroelectric project in China. The proposed velocity distribution formula was applied to the solid boundary as considered by the method of images. A good agreement was again observed between the prediction and the measurements. © 2011 International Association for Hydro-Environment Engineering and Research.

Population dynamics of killifish Aphanius dispar (Ruppel) in Sandspit area off Karachi

Growth and mortality parameters of Aphanius dispar a cyprinoides generally observed in the catches of near shore area were estimated from the length frequency data collected from Sandspit area of Karachi, using LFSA. The von Bertalanffy growth parameters were estimated as Loo=71.73 mm & K=L35/yr for Male Aphanius dispar and Loo=70.66 & K=l.41 for female. Total Mortality coefficient (Z) was estimated using Length converted catch curve which is equal to 2.12/yr, for male and for female 2.19/yr. Natural mortality (M) was estimated by Pauly's empirical formula: M=l.64/yr (male) and 1.70/yr (female). The species also displayed two cohorts a year.

Biology of Bombay duck, Harpodon nehereus (Ham., 1822), from Mumbai waters, India

Morphometric and meristic study of Harpodon nehereus (Hamilton, 1822) from Mumbai waters indicated that the specimens belonged to a homogenous population. Based on the meristic study, the fin formula can be written as B sub(23-269), D sub(12-139), P sub(11-139), V sub(9), A sub(13-15), C sub(19), L sub(40). Length-weight study revealed an allometric relationship, presented as Log W= -3.1362 + 3.6059 Log L. The analysis of food and feeding habits revealed the species to be voracious, carnivorous and cannibalistic, feeding mainly on Acetes spp., juveniles of H. nehereus itself, prawns and Coilia dussumieri. The feeding intensity was found to be the maximum during September and November, and also in mature specimens which may be the preparation for the ensuing spawning activity. Reproductive biology indicated two peak spawning seasons in November and March. However, the species as a whole has prolonged breeding season and spawning occurs throughout the year. Average fecundity was estimated as 314 ova/g body weight of fish and the length at which 50% of female specimens mature (Lc sub (50)) was calculated as 255 mm.

Heterorhabditidoides chongmingensis gen. nov., sp nov (Rhabditida : Rhabditidae), a novel member of the entomopathogenic nematodes

During a recent soil sample survey in Eastern China, a new entomopathogenic nematode species, collected from the Chongming Islands in the southern-eastern area of Shanghai, was discovered. Morphological characteristics of different developmental stages of the nematode combined with molecular data showed that this nematode is a new genus of Rhabditidae, and described as Heterorhabditidoides chongmingensis gen. nov., sp. nov., for that it shares more morphological characteristics with heterorhabditids than with ste-inernematids. For males, the papillae formula of bursa is 1, 2, 3, 3, with constant papillae number in the terminal group, stoma tubular-shaped and about 1.5 head width; cheilorhabdions cuticularized, esophageal collar present and long, median bulb present. For infective juveniles, EP = 90 (80-105) mu m, ES = 104 (92-120) mu m, tail length = 111 (89-159) mu m, and a = 19.1 (15-21). The percentages of the nucleotides A, T, C and G in the ITS1 regions of the new species are significantly different from those of heterorhabditids and other rhabditids. Molecular phylogenetic trees based on 18S rDNA and the internal transcribed spacer (ITS) sequences data revealed that the new entomopathogenic nematode species forms a monophyletic group, which is a sister group of the clade comprised of some genera of Rhabditidae. (c) 2008 Elsevier Inc. All rights reserved.

Studies on the influence of moisture and specific gravity on the strength properties of mango wood (Mangifera indica)

Influence of moisture and specific gravity on the strength of mango wood is discussed. The co-efficient of correlation between specific gravity and breaking strength was found to be non-significant. The relation of strength and moisture was found to be highly significant. The mean strength values indicated a reduction in strength when the moisture increased from 8.5 to 18.8%. However no appreciable difference in strength values could be observed when moisture increased above 37%. The strength-moisture relationship is a straight line, passing approximately through the fibre saturation point. By using the exponential formula, the breaking strength corresponding to any moisture level between zero and fibre saturation can be determined.

Prediction of drained weight in canned prawn under commercial conditions

A general formula for the prediction of drained weight of canned prawn processed under laboratory condition has been worked out earlier (Chaudhuri et al., 1978). Attempts were made in this communication to modify the general formula to predict the drained weight under commercial conditions of processing particularly blanching, as the moisture content of meat depends on the quantum of heat received during blanching (Govindan, 1975).

Studies on thermal deffusivity [i.e. diffusivity] and conductivity of fresh and dry fish

Thermal diffusivity (α) and conductivity (K) of fresh and dry cured fish at different moisture levels were investigated by a calorimeter (regular regime) method and transient line source technique. Thermal conductivity has a linear correlation with packing density and percentage water content. K values calculated from formula method and line source technique are comparable.

Genetic diversity of Chinese native pigs inferred from protein electrophoresis

We examined protein polymorphism of 20 native pig breeds in China and 3 introduced pig breeds. Thirty loci have been investigated, among which six loci were found to be polymorphic. Especially, the polymorphism of malate dehydrogenase (MDH), adenylate kinase (AK), and two new alleles of adenosine deaminase (ADA) had not been reported in domestic pigs and wild pigs. The percentage of polymorphic loci (P), the mean heterozygosity (H), and the mean number of alleles (A) are 0.200, 0.065, and 1.300, respectively. The degree of genetic variability of Chinese pigs as a whole was higher than that of goats, lower than that of cattle and horses, and similar to that of sheep. Using the gene frequencies of the 30 loci, Nei's genetic distance among the 20 native breeds in China and 3 introduced pig breeds was calculated by the formula of Nei. The program NEIGHBOR in PHYLIP 3.5c was chosen to construct an UPGMA tree and a NJ tree. Our results show that, of the total genetic variation found in the native pig breeds in China, 31% (0.31) is ascribable to genetic differences among breeds. About 69% of the total genetic variation is found within breeds. Most breeds are in linkage disequilibrium. The patterns of genetic similarities between the Chinese native pig breeds were not in agreement with the proposed pig type classification.

Length-weight relationship of two palaemonid prawns, Macrobrachium idella and M. scabriculum: a comparative study

Length-weight relationships of two commercially important freshwater prawns, Macrobrachium idella and M. scabriculum, have been worked out separately for the two sexes of the two species. 't' test showed that growth departs significantly from the isometric growth in the case of both sexes of M. idella and in the female of M. scabriculum. Therefore, the cubic formula W = CL^3 may be applied only in the case of males of M. scabriculum. In all the other cases W = CL^n may be followed.

Length-weight relationship in Nandus nandus (Hamilton) (Perciformes-Teleostei)

Length-weight relationship of the freshwater fish of Pamba River, Nandus nandus (Ham) has been worked out. The results showed that the slope values and elevations were not significant and hence a combined regression equation has been calculated for both the sexes (Log W=2.4130 Log L -0.3306). The’t’ test analyses were conducted and found that the growth departs significantly from the isometric growth. Thus the formula W=aL super(n) has to be applied in calculating the length-weight relationship of this species.

Genetic diversity of Bartail flathead (Platycephalus indicus (Linnaeus,1758)) using AFLP markers in Persian Gulf

Platycephalus indicus is a large benthic fish that inhabits temperate and tropical coastal waters of the Indo-West Pacific and found on sand or mud bottom in vary shallow area of estuary and near shore to depth of 25m. This species is dominant species of platycephalidae family, in Khuzestan, Bushehr and Hormozgan provinces and mainly is captured by bottom trawl, gillnet and moshta in Hormozgan. This study was designed to evaluate population variation and differentiation of bartail flathead (Platycephalus indicus (Linnaeus, 1785))in the Iranian waters of Persian Gulf using the morphometric and meristic characters and by AFLP marker. . A total 180 fish specimens were collected by gill net from six station(khor mosa, bahrekan, shif, motaf, charak and bandar abbas) that was 30 individual related to every station in Iranian shores of Persian Gulf . 28 morphometric factors and 11meristic specialties were measured and morphometric factors was standardized with Beacham formula. Univariate analysis of variance (One-way ANOVA) revealed significant differences with varying degrees between the means for 21 standardized morphometric measurements and 6 meristic counts that showed high significant differences between the six stations sampling. Discriminate function analysis (DFA) or the overall random assignment of individuals into their original groups was for morphometric and meristic characters was 47.9% and 53.9% respectively. The data were subjected to a principle component analysis (PCA) which grouped in eight and four factors for morphometric and meristic charactersrespectively.. Genetic diversity of six populations of bartail flathead (Platycephalus indicus) was investigated using amplified fragment length polymorphism (AFLP). A total of 118 reproducible bands amplified with ten AFLP primer combinations were obtained from 42 fishes that were collected from six different locations in the northern of Persian Gulf. The percentage of polymorphic bands was 57.06%. Average of Nei’s genetic diversity was 0.200±0.008, and Average of Shannon’s index was 0.300±0.011. The results of AMOVA analysis indicated that 66% of the genetic variation contained within populations and 34% occurred among populations and gene flow was 0.6454.The estimated level of population differentiation asmeasured by average Fst value across all loci was 0.327. Plotting discriminant functions 1 and 2 and UPGMA dendrograms based on Euclidian distance and genetic distance also showed at least five separate populations of bartail flathead in the northern Persian Gulf.

Kilka population dynamics in the south of the Caspian Sea

Populations of kilka in the Caspian Sea have important role in the food chain. This study was conducted to determine population parameters of three species of kilka in the south of the Caspian Sea, during 2006-2007. Mean length was 102.4±9.7 mm for common kilka, 117.8±6.9 mm for anchovy and 119.5±10.9 mm for bigeye. The relationship between length and weight indicated the negative allometric growth in the all three species. Mean age for common kilka, anchovy and bigeye were 3.6, 4.6 and 4.6 years, respectively. Sex ratio (M:F) were 0.52:1 for anchovy, 0.60:1 for common kilka and 1.60:1 for bigeye. The value of growth coefficient (K) was the highest (0.321) for the common kilka, (0.267) for the bigeye, and the lowest for the anchovy kilka (0.245). Total mortality estimated from the descending of the catch curve using the age structure, Z=1.280 yr-1 for common kilka, Z=1.067 yr-1 for anchovy, and Z=1.015 yr-1 for bigeye. Natural mortality (M) were estimated using Pauly formula as M=0.622, M=0.537 and M=0.503 per year for common kilka, bigeye and anchovy, respectively. Value of fishing mortality (F) were estimated from Z and M, as F=0.658 for common kilka, F=0.564 for anchovy and F=0.478 for bigeye. The exploitation rate (E) were estimated E=0.514 for common kilka, E=0.528 for anchovy and E= 0.471 for bigeye. The estimate of MCY (Maximum Constant Yield) was calculated using the more reliable time series of commercial catch data from 2001-2007, which resulted in an estimate of MCY for the kilka fishery of 14100 tonnes.

The study of biological characteristics and determination of population dynamic parameters of sawtooth barracuda (Sphyraena putnamae) in the Persian Gulf (Hormozgun Province waters)

The biological characteristics and population dynamisms of Sphyraena putnamae, were studied in the northern Persian Gulf and Oman Sea restricted to Hormuzgan province waters within 13 months period, from November 2006 up to November 2007. Biometrical and anatomical measurements were carried out, and biological surveys were conducted on 486 specimens. On the other hand, the growth and mortality parameters were estimated by using 3096 samples. These samples were collected from 3 landings, namely Bandar Abbas, Bandar Lengeh and Bandar Jask. The measurements of the minimum and maximum Fork lengths and weights were 11.7 to 8.03 cm and 135.0 to 4140.0 g, respectively. The results indicated that this species, having the Relative Length of Gut, RLG=0.34±0.002, is strongly carnivorous (often fish-eater), proven by the fact that more than 98% of its stomach contents were fish pieces. Examining the changes in the index of stomach emptiness by the percentage of CV = 0.47% indicates that this fish is Moderate feeder. The level of feeding increased in March, before spawning and decreased in June and September, simultaneously with the spawning season. There are 2 peaks of reproduction or spawning seasons during the months of April-May and September, of which the prior is assumed as the main spawning. The sex ratio (M:F) was calculated 0.5:1.0(X2 =2.11), which did not show a significant difference with expected level of 1:1 (P>0.05). The average absolute and relative reproduction rates of Sphyraena putnamae is respectively as follows: 1866827.1±255448.9 and 1097.7±94.3. The highest and the lowest diameter of matured egg are from 200 to 750 μ, and its average diameter is 402.10 ± 0.190 μ. A parameter for Saw-tooth barracuda length measurement, Lm50, based on the Fork-length, was calculated as 54.01 cm. In other words, as far as the fisheries management is concerned, the fish whose lengths are less than 54.01 cm should not be caught. The calculated level of (R2) (correlations of total length & weight), indicated strong correlations between length and weight of this fish, and the obtained formula included W =0.007100 FL 2.9295 and reinforced this assumption. The “K” Index for this fish in 3 above mentioned landings (Jask, Bandar-Abbas and Bandar-Length) were 1.24, 0.37 and 0.46 per year, respectively and the FL index for the same landings were estimated as 129, 110 and 134 cm, respectively. The growth coefficient (MONRO) for the above mentioned regions were calculated as 3.601, 3.647 and 3.917, respectively; and in the surveyed regions there were no significant differences in populations. The Total mortality coefficient (Z) was calculated 0.76, 1.12 and 1.07 per year, the Natural mortality coefficient was 0.46, 0.63 and 0.70, and the Fishing mortality coefficient (rate) (F) was found to be 0.30, 0.49 and 0.37 per year. The value of the exploitation rate (E) is equal to 0.39 per year, indicating that this species is an under-exploited resource, and there is no excessive fishing pressure on the fish supply of this species in the afore-said regions. The highest level of exploitation was found for ‘Bandar Abbas’ fishing region and the lowest level of exploitation is in ‘Bandar Lengeh’ waters.