162 research outputs found

    Reproduction biology of Penaeus merguiensis (banana prawn) emphesis of fecundity in coastal waters of Hormozgan Province, Iran

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    Penaeus merguiensis is the dominant species in coastal waters of Hormozgan province and approximately constitute 70% of the annual catch composition. Sex rate is analysis in natural population shows that the proportion of males to females is 1:1 and generally this proportion in carapace length is 28.6 and 25.7 mm more than other classes, which its peak is observed in 25.7 mm length class. Also proportion of males to females in May to December and April to May is more than other times which its peak is in December. The analysis of sexual maturation based on carapace length shows that LM50 for females of this species has followed the exponential equation and is equal to 32.8 mm (r^2 = 90%). Minimum and maximum of absolute fecundity of this species with 20.7-31.5 mm C.L. are and 11300 and 14400 eggs respectively. This analysis of relative fecundity of this type showed that the relationship between carapace length and number of eggs was a type of poweral equation (F= 0.1208 C.L 3.8, r^2 = 97%), however this relationship between total length (T.L) and wet weight (W) was F = 0.0002 T.L 7.1 (r^2= 0.68) and F= 0.1942 W 4.02 (r^2=0.58), respectively, which showed the fecundity has 0.1942 W (r more correlation with the carapace length

    Trophic level, food preference and feeding ecology of Rachycentron canadum (Linnaeus, 1766), in Hormuzgan Province waters (northern Persian Gulf and Oman Sea)

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    This study examined the ecological factors associated with feeding in Rachycentron canadum (cobia) in the waters of Persian Gulf and Oman Sea. Seasonally variation of stomach condition of cobia male, females, pooled and size wise were analyzed. In general, 577 cobia were collected (340 males, 237 females) (20–161 cm Total length) from Sept. 2014 to Sept. 2015 by the Ferdows-1 survey ship and from the landing areas in Bandar Abbas harbor seasonally. Our results provide the first estimates of trophic level (Tr.L) (4.32±0.76, mean±Se), consumption per biomass (Q/B) (6.13), and aspect ratio of the caudal fin (ARc.f) (3.1) for R. canadum in the Hormuzgan Province. We also found that bony fish made up more than 80 percent of the relative importance of particular prey (IRI %), indicating R. canadum primarily preys on these species. The immature group (20–40 cm, T.L), tended to feed on Penaeidae family, small crabs, and mollusks. Hierarchical clustering revealed that the frequencies of different types of prey could be applied to categorize the length classes into three levels. The result of this study revealed that the immature group and the 20-40 cm length class tended to feed on Penaeidae family, crabs, and mollusks. Also, we found that males generally fed more than females in all seasons and that R. canadum had an average dietary intake. The findings of this study can be used to prepare a food formulation for cobia that resembles the native diet

    Feeding habits of yellowfin seabream (Acanthopagrus latus) in the northern region of the Persian Gulf

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    Feeding habits of yellowfin seabream (Acanthopagrus latus) was investigated in coastal waters of the Northern Persian Gulf. This investigation was conducted by monthly sampling of thirty fish from September 2011 through August 2012. Fish size ranged from 17.98 ± 2.07 to 32.31 ± 6.52 cm in total length and from 134.01 ± 45.62 to 720.46 ± 292.58 g in weight. The highest value of gastro-somatic index was obtained in September (5.22 ± 0.04) and the lowest in December (1.61 ± 0.03) with annual average of 2.50 ± 0.60. The result of gastro-somatic index revealed that the highest feeding activity of A. latus was during autumn. The highest level of vacuity index was observed in summer (34.95 ± 4.71) and the lowest in autumn (25.88 ± 2.71) indicating that the highest number of empty stomachs was in summer. Annual average of vacuity index was 30.14 ± 5.72 exhibiting that A. latus was comparatively gluttonous in the Northern Persian Gulf. Bivalves and shrimps were the major food items found in the stomach of A. latus showing food preference indices of 45.86% and 30.67%, respectively. Other food items included crabs (12.66%), aquatic plants (4.05%), animal derivatives (4.52%) and gastropods (2.23%). According to the results, animal derivatives, aquatic plants and gastropods were eaten accidentally and were not the food items of A. latus in coastal waters of Hormozgan. The average relative length of gut was 1.41 ± 0.15 showing that A. latus was omnivorous in this region

    Density index and length scale of Pearl Oyster Pinctada radiata in two habitats around Hendorabi Island (Iran, the Persian Gulf)

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    As pearling has been banned in Iran since 2006, stocks of pearl oysters has not been investigated during these years; therefore, condition of natural habitats for Pinctada radiata in its old habitats was surveyed in present research. Shallow waters around Hendorabi Island were searched with diving and two habitats namely “Sooleh” and “Sahel-e-sheni”, were considered for study. The pearl oysters had most distribution in these habitats in depth ranges of 7 to 12 m and 8 to 11 m, respectively. Total stock in Sooleh and Sahel-e-sheni was surveyed near 35700 and 12563 Pinctada radiata, respectively, of which 22% and 67% were catchable, respectively. Catch Per Unit of Area (CPUA) in Sooleh and Sahel-e-sheni habitats was estimated equal to 0.3 N/m2 in both habitats, and Catch Per Unit of Effort (CPUE) in these habitats was calculated equal to 59.5 N/hr and 50.3 N/hr, respectively. Results of this study demonstrated that area, stocks and CPUA for studied habitats were less than previous years. Despite of interdict of pearling in this region since 7 years ago, stock revival has done slowly

    Imaging stress and magnetism at high pressures using a nanoscale quantum sensor

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    Pressure alters the physical, chemical and electronic properties of matter. The development of the diamond anvil cell (DAC) enables tabletop experiments to investigate a diverse landscape of high-pressure phenomena ranging from the properties of planetary interiors to transitions between quantum mechanical phases. In this work, we introduce and utilize a novel nanoscale sensing platform, which integrates nitrogen-vacancy (NV) color centers directly into the culet (tip) of diamond anvils. We demonstrate the versatility of this platform by performing diffraction-limited imaging (~600 nm) of both stress fields and magnetism, up to pressures ~30 GPa and for temperatures ranging from 25-340 K. For the former, we quantify all six (normal and shear) stress components with accuracy <0.01<0.01 GPa, offering unique new capabilities for characterizing the strength and effective viscosity of solids and fluids under pressure. For the latter, we demonstrate vector magnetic field imaging with dipole accuracy <1011<10^{-11} emu, enabling us to measure the pressure-driven αϵ\alpha\leftrightarrow\epsilon phase transition in iron as well as the complex pressure-temperature phase diagram of gadolinium. In addition to DC vector magnetometry, we highlight a complementary NV-sensing modality using T1 noise spectroscopy; crucially, this demonstrates our ability to characterize phase transitions even in the absence of static magnetic signatures. By integrating an atomic-scale sensor directly into DACs, our platform enables the in situ imaging of elastic, electric and magnetic phenomena at high pressures.Comment: 18 + 50 pages, 4 + 19 figure

    Applying Markov decision process to understand driving decisions using basic safety messages data

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    While a number of studies have investigated driving behaviors, detailed microscopic driving data has only recently become available for analysis. Through Basic Safety Message (BSM) data from the Michigan Safety Pilot Program, this study applies a Markov Decision Process (MDP) framework to understand driving behavior in terms of acceleration, deceleration and maintaining speed decisions. Personally Revealed Choices (PRC) that maximize the expected sum of rewards for individual drivers are obtained by analyzing detailed data from 120 trips and the application of MDP. Specifically, this paper defines states based on the number of objects around the host vehicle and the distance to the front object. Given the states, individual drivers’ reward functions are estimated using the multinomial logit model and used in the MDP framework. Optimal policies (i.e. PRC) are obtained through a value iteration algorithm. The results show that as the number of objects increases around a host vehicle, the driver prefer to accelerate in order to escape the crowdedness around them. In addition, when trips are segmented based on the level of crowdedness, increased levels of trip crowdedness results in a fewer number of drivers accelerating because the traffic conditions constrain them to maintaining constant speed or deceleration. One potential application of this study is to generate short-term predictive driver decision information through historical driving performance, which can be used to warn a host vehicle driver when the person substantially deviates from their own historical PRC. This information could also be disseminated to surrounding vehicles as well, enabling them to foresee the states and actions of other drivers and potentially avoid collisions

    Supporting 'design for reuse' with modular design

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    Engineering design reuse refers to the utilization of any knowledge gained from the design activity to support future design. As such, engineering design reuse approaches are concerned with the support, exploration, and enhancement of design knowledge prior, during, and after a design activity. Modular design is a product structuring principle whereby products are developed with distinct modules for rapid product development, efficient upgrades, and possible reuse (of the physical modules). The benefits of modular design center on a greater capacity for structuring component parts to better manage the relation between market requirements and the designed product. This study explores the capabilities of modular design principles to provide improved support for the engineering design reuse concept. The correlations between modular design and 'reuse' are highlighted, with the aim of identifying its potential to aid the little-supported process of design for reuse. In fulfilment of this objective the authors not only identify the requirements of design for reuse, but also propose how modular design principles can be extended to support design for reuse

    Study of biological characteristics of jack knife clam Solen dactylus (Coscl, 1989) in Bandar Abbas coast

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    In this study, 945 Specimens of bivalve Solen dactylus were biometrically assessed from April 2007 to March 2008 in two transects of Golshahr coast in Bandar Abbas, Persian Gulf. Physical and chemical factors of water like temperature, pH, salinity, dissolved oxygen, coast's sediment, diversity and abundance of phytoplankton were studied monthly during the clam sampling. The mean clam length and total weight were 67.5 plus or minus 17.13mm and 6.3 plus or minus 4.04g, respectively. The relationship between clam length-width, total weight-dry weight and clam length-dry weight were significant (r^(2) = 0.91, r^(2) = 0.83 and r^(2) = 0.86, P0.05). The maximum value of Gonadosomatic Index (GSI) in the first and second transect were 11% and 16%, respectively in January (reproductive cycle). The minimum value of GSI in both transects was zero from April to September. Gonado Condition Index (GCI) was synchronous with the GSI during the year of study. GSI and GCI showed a negative relationship with temperature and a positive relationship with dissolved oxygen
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