Recent Submissions

  • Least-Squares Reverse Time Migration in Pseudodepth Domain and Its Application

    HUSSEIN MUHAMMED, HUSSEIN ABDUELHALEIM (China University of Petroleum (East China), 2022-06-30)
    The Cartesian-based least squares reverse time migration (LSRTM) aims to obtain a relatively high-resolution amplitude preserving imaging by calculating and solving the Hessian matrix. In addition, conjugate gradient algorithm is proved to be an efficient iterative method, which makes the traditional LSRTM feasible in practical data processing applications. Each iteration process of LSRTM includes two main parts; The first part is the forward simulation of wavefield, and the second part is the back propagation of wavefield. However, the calculation of these two parts takes a lot of time, and oversampling effects will occur in the calculation process. The thesis develops a smooth understanding of the LSRTM scheme in pseudodepth domain and gives information about this type of wavefield extrapolation method to achieve amplitude-preserved image with low computational costs in terms of memory and time. The underground media faced by seismic exploration usually include low velocity bodies, high steep structures and pore fracture units. When simulating the seismic wavefield in these media, in order to ensure the simulation accuracy and computational stability by finite difference methods, the grid spacing needs to be very small, which leads to the oversampling problem of the traditional finite difference forward simulation method in Cartesian coordinate system. In order to overcome this problem, the pseudo depth domain algorithm is applied to the least-squares reverse time migration to improve its computational efficiency. The problem of stabilizing this Pseudodepth wavefield arises from the introduction of the mapping function and velocity and also the vertical axis operator that converts the finite difference solution partially from time into frequency domains. Stability and convergence analysis suggests that the spatial derivatives of Riemannian axis should be approximated by a mixed Fourier pseudo-spectral and ordinary finite-difference schemes methods using a special Gaussian-like impulse function to generate the vector-matrix of the complex source term within the finite-difference operator, in addition to the mapping velocity, which is a differential form of the initial input velocity model, manifestly controls the CFL conditions of the associated Riemannian-finite difference operator. Numerical and synthetic examples indicated that this approach is more stable and efficient in extrapolating a smooth Riemannian wavefield while maintaining Claerbout’s principle for locating subsurface reflectors also choosing an appropriate sampling rate for the new vertical axis is related inversely by the maximum frequency of the impulse wavelet and directly with minimum velocity value in the given model. The LSRTM wavefield extrapolation usually uses the two-dimensional constant density acoustic wave equation, by considering the change of velocity field distribution, and converts it to the corresponding pseudodepth domain, so as to solve the oversampling problem in the true depth domain. For each point in the Cartesian coordinate system, there is a corresponding point in the pseudo depth domain. Therefore, we can interpolate and remodel the reconstructed finite difference modelled wavefield in the new coordinate system through the Cartesian-to-pseudodepth mapping function. Regardless of the applied finite difference algorithm and boundary conditions, wavefield extrapolation in pseudodepth domain can ensure high accuracy and efficiency. Through the test of synthetic and actual data, compared with the traditional LSRTM results, pseudodepth domain LSRTM shows great potentiality in amplitude preserving imaging. On the other hand, pseudodepth domain LSRTM has great advantages in computational efficiency and ensures computational accuracy.
  • New records of coral diseases in the Persian Gulf

    Tavakoli-Kolour, Parviz; Hazraty-Kari, Sanaz (2019-11-26)
    Journal of Threatened Taxa
    We report first observations of three coral diseases including black band disease on Acropora, a syndrome resembling yellow band disease and red band disease on Porites colonies from depth 5–6 m at Abu-Musa Island after widespread coral bleaching in the northern part of the Persian Gulf in October 2012.
  • Quantifying recent trends in seagrass cover and biomass in a stressed environment, Pulau Semakau, Singapore

    Bramante, James F. (National University of Singapore, Department of Geography, 2014-11-20)
    Globally, seagrass habitats have experienced sharp declines over the past century, with an annual loss of seagrass cover of 7%yr-1 since 1990. Despite the attention to seagrass this decline has brought, little research has been directed towards trends of seagrass habitats in Singapore. The research presented here developed and applied remote sensing methods to partially fill this gap, provide tools for more extensive monitoring in the future, and contribute to the global body of seagrass research. Satellite images from four different satellite sensors were used to estimate seagrass bed extent in Singapore’s second largest seagrass meadow, at Pulau Semakau, from 2001 to 2013. Statistical estimates of image signal-to-noise ratios were used to screen images for quality. Validation data collected in 2013 were used to estimate error for supervised classifications produced from each sensor. A novel method was explored to account for macroalgae blooms in the study area, but the resulting correction could not be validated and did not affect the overall trends in seagrass bed extent. In addition to the classification analysis, an empirical model linking remote sensing reflectance to above-ground biomass was constructed to examine the distribution of seagrass within the meadow. Applied to WV2 images from 2011 and 2013, this model produced estimates of above-ground biomass with root mean squared error (RMSE) of 54 gm-2 and 44.7 gm-2, respectively, within ranges of 0-288 gm-2 and 0-229 gm-2, respectively. A novel index to measure seagrass density non-destructively was developed to help conservation and monitoring efforts. This index, normalized canopy index (NCI), was estimated from satellite imagery more precisely than above-ground biomass, producing estimates from the 2013 WV2 image corresponding to field data with an R2 of 0.71 relative to the R2 of 0.39 produced by the above-ground biomass model. This index may be a promising, non-destructive alternative to above-ground biomass for remote sensing studies and should be pursued further in future research. Based on the time-series classification analysis, seagrass bed extent at Pulau Semakau declined from over 44.6 ha in April 2002 to 25.3 ha in June 2013. This decline occurred at an average of 5.1%yr-1 from 2001 to 2013, although this rate of decline slowed to 3.7%yr-1 in 2012. These declines are likely representative of other seagrass habitats in Singapore. Broader monitoring is required to determine to what extent Singapore’s seagrasses are disappearing. Although seagrass bed extent declined by 17% from April 2011 to June 2013, over the same time period total above-ground biomass in the seagrass meadow declined only 5%, from 41.6 Mg to 39.6 Mg. Two acute sedimentation events recorded over this time period corresponded to a large and permanent decrease in bed extent captured by WV2 imagery and a small and temporary decrease in bed extent captured by ALI imagery. I hypothesize that the discrepancy in decreases in extent and biomass, coupled with an increase in median biomass, is attributable to preferential survival and recolonization of dense-biomass seagrass species during these sedimentation events. Measurements of seagrass species abundance during this time period provide support for this hypothesis. This exercise demonstrates the advantages and limitations of monitoring seagrass bed extent and above-ground biomass. Bed extent provides a measure of overall viability of a seagrass meadow, but above-ground biomass provides a better index of spatially variable health and internal change. Coupled, these two measurements provide greater insight into complex seagrass bed processes and seagrass response to disturbance.
  • Étude morphologique et physiologique du sang, de l'immunité naturelle et acquise chez quelques poissons Indochinois

    Durand, J. (1950)
    Annales de l'Institut Océanographique, Paris
    This paper deals with a morphological study on blood of some Indochinese freshwater fishes. The study has been split in two parts: one dedicated to compare some fishes' blood and the second part focused on reaction of cells and natural immunity.
  • Guideline of fishery drug application (NY5071-2002)

    Zou, W.; Yang, C.; Jiang, I.; Wu, S.; Yi, Q.; Wu, J.; Pearl River Fisheries Research Institute, Shanghai Fisheries University,Guangdong Entry-Exit Inspection and Quarantine Bureau (2002)
  • Hubungan panjang berat dan faktor kondisi tiga jenis ikan yang tertangkap di perairan Kuala Gigieng, Aceh Besar, Provinsi Aceh

    Mulfizar, Mulifizar; Muchlisin, Z.A.; Dewiyanti, Irma (2012)
    The study of the length weight relationships and condition factors of the brackishwater fishes found in Kuala Gigieng was conducted. The objective of the present study was to evaluate the growth patterns and condition factor of thebelanak (Mugil cephalus), seriding (Ambassis koopsii) and petek (Leiognathus fasciatus). The sampling was conducted for eight time on July 2011 by using gillnet and castnet. The results showed that the belanak (M. cephalus) and seriding (A. koopsii) have allometric negative growth patten, while the petek (L. fasciatus) has an allometric positive. In addition, the relative weight condition factor’s was higher than 100. And the Fulton’s condition factor were not different significantly among fishes. Indicating the condition of the Kuala Gigeng is relatively in good condition and support fish growth as well.
  • Genetic identification of four Malaysian mackerel species off Coast of Peninsular Malaysia based on molecular marker

    Muchlisin, Z.A.; Masazurah, A.R.; Abu Talib, A.; Siti-Azizah, M.N.; Samsudin, B.; Jamsari, A.F.J. (2009)
    Random Amplified Polymorphic DNA (RAPD) markers and cytochrome b (Cyt-b) gene sequences were utilizedto fingerprint and construct phylogenetic relationships among four species of mackerel commonly found in the Straits ofMalacca namely Rastrelliger kanagurta, R. brachysoma, Decapterus maruadsi and D. russelli. The UPGMA dendogramand genetic distance clearly showed that the individuals clustered into their own genus and species except for theDecapterus. These results were also supported by partial mtDNA cytochrome b gene sequences (279 bp) which foundmonotypic sequence for all Decapterus studied. Cytochrome b sequence phylogeny generated through Neighbor Joining(NJ) method was congruent with RAPD data. Results showed clear discrimination between both genera with averagenucleotide divergence about 25.43%. This marker also demonstrated R. brachysoma and R. kanagurta as distinct species separated with average nucleotide divergence about 2.76%. However, based on BLAST analysis, this study indicated that the fish initially identified as D. maruadsi was actually D. russelli. The results highlighted the importance of genetic analysis for taxonomic validation, in addition to morphological traits.
  • Crude protein and amino acids content in some common feeds of tiger grouper (Epinephelus fuscoguttatus) juvenile

    Muhammadar, A.A.; Mazlan, A.G.; Samat, A.; Muchlisin, Z.A.; Simon, K.D. (2011-10-30)
    AACL Bioflux
  • Estimation of production trend of the depik, Rasbora tawarensis (Teleostei, Cyprinidae), in Lake Laut Tawar, Indonesia

    Muchlisin, Z.A.; Fadli, N.; Rudi, E.; Mendo, T.; Sit-Azizah, M.N. (2011-12-30)
    AACL Bioflux
  • Studi Pendahuluan Kualitas Air Untuk Pengembangan Budidaya Perikanan di Kecamatan Sampoinit Aceh Jaya Pasca Tsunami

    Muchlisin, Z.A (2009)
    The preliminary study of water quality assessment for developing aquaculture effortwas done in Sampoinit sub district for one week (1-8 December 2007). The objective of the presentstudy is to evaluate the suitability of sites for developing of aquaculture. The explorative surveymethod was used in this study by determine of several sampling points at identified sites. Thesurvey was covered four villages i.e. Meunasah Kulam, Crak Mong, Krueng No dan Pulo Raya. The results show that Meunasah Kulam, Crak Mong, Krueng No dan Pulo Raya were suitable for brackish water aquaculture of Scylla serrata, Mugil sp, Tilapia mossambica), Tilapia nilotica andChannos channos, while Crak Mong was suitable for freshwater aquaculture of Clarias batrachus and Channa striata. A semi intensive of aquaculture was suitable to be developed.
  • Human Resources Development for Sustainable Aquaculture in Bangladesh

    Zamal, Hossain; Das, Uzzal Kanti; Barua, Prabal (2008)
    Social Change
    The ennoblement of human resources has become a prime issue in the philosophy of sustainable aquaculture development in the new millennium.Being the planners, designers, conductors and philosophers of sustainable aquaculture, human beings always demand their further improvement atlevel best from their current positions to bring supreme success in the sector. As sustainable aquaculture is socio-economic –cum-environmental in concept, its operation and management requires constant interplay of various human knowledge for ensuring its smooth direction and forachieving its goal. So, the arrangement of different types and levels of training and education are the great need for the development of personnel involved in sustainable aquaculture route and also for growing awarenessof environmental issues. The modus operandi of training and education has to be changed systematically to answer the calls of the needs of the new millennium. In the developing and developed countries where aquaculture plays a vital role in promoting production of aquatic organisms, alleviating of poverty, ensuring environmental compatibility, replenishing and improving the natural stocks, increasing socio-economic upliftment through integrated development approach, developing and managing theaquatic resources, maintaining gene banks and preserving the diversity of fish stocks, it has been already proved that Human resources development (HRD) is inevitable to bring sustainable aquaculture and plays a great role in the flourishment of the system . Different types and levels oftraining of personnel required for sustainable aquaculture in the new millennium are brought forward in the study. The importance of human resources development (HRD) through specialized training to the personnel is also depicted.
  • Determination of optimum stocking density of Macrobrachium rosenbergii larvae using multiple feed in a commercial hatchery at Cox’s Bazar, Bangladesh

    Uddin, Nazim; Hossain, Shahadat; Das, Nani Gopal; Chowdhury, Shahnawaz; Barua, Prabal (2010)
    Aquanet Magazine
    Experimental stocking density of Macrobrachium rosenbergii in larval rearing was conducted in A.G. Aqua Hatchery, Chakaria, Bangladesh to study the effect of different stocking densities on growth, survival rate and diseases stress under hatchery condition. The research work was conducted using six cemented rectangular tanks having 3m3 capacity (1.5mX2mX1m) each. Stocking density were maintained in three experimental setup as 200, 150 and 100ind/L of the T1, T2 and T3 respectively with one replicate each. The larvae were fed with Artemia nauplii, Custard, Maxima and brine shrimp flakes. Water quality was maintained by exchanging 20-30% (12ppt saline water) daily. During the study period, temperature, pH, DO, salinity, nitrite-nitrogen, ammonia and alkalinity were maintained from 28.5-31.5ºC, 7.5-7.8, 5.8-5.9mg/L, 12-13ppt, 0.14-0.2 mg/L, 0.22-0.3mg/L, and 140-160mg/L respectively. The growth rates of larvae at 11th stage were recorded in terms of body length 0.115, 0.136, and 0.169 mm/day whereas body weight were observed 0.000115, 0.000180, and 0.000240g/day. The survival rate of larvae were found 21.8%, 30.4% and 51.3% in treatments T1, T2 and T3 respectively. PL was obtained as 43, 45, and 51PL/L and days required of 41, 38 and 34 days in stocking density of 200, 150, and 100ind/L respectively. It was found that the minimum of 34 days was required to attain the PL (12th stage) using the stocking density of 100 individuals/L. Cannibalism, Zoothamnium, Exuvia Entrapment Disease (EED), and Bacterial Necrosis (BN) were found to be the threat to the commercial hatchery operation that might responsible for potential larval damages which can be reduced by lowering the stocking densities in larval rearing tank that also increased the survival and growth rate.
  • Climate change and its risk reduction by mangrove ecosystem of Bangladesh

    Barua, Prabal; Chowdhury, Shahnawaz; Sarker, Subrata (2010)
    Bangladesh Research Publication Journal
    Climate change is amongst the most dreaded problems of the newmillennium. Bangladesh is a coastal country bounded by Bay ofBengal on its southern part and here natural disasters are anongoing part of human life. This paper discusses about the possibleimpact of climate change through tropical cyclones, storm surges,coastal erosion and sea level rise in the coastal community ofBangladesh and how they cope with these extreme events by thehelp of mangrove ecosystem. Both qualitative and quantitativediscussions are made by collected data from different researchwork those are conducted in Bangladesh. Mangrove ecosystemprovides both goods and services for coastal community, helps toimprove livelihood options and protect them from natural disasterby providing variety of environmental support
  • Estimation of growth and financial analysis through the application of Ipil ipil (Leucaena leucocephala) leaf meal as supplements to soybean and fish meal in the diet of juvenile monosex tilapia (Oreochromis niloticus)

    Zamal, Hossain; Barua, Prabal; Uddin, Belal (2009)
    International Aqua Feed
    Among plant protein ingredients,ipil ipil (Leucaena leucocephala) leafmeal (ILLM) is considered the most nutritive plant protein source after soybean meal in aquaticfeeds. That was proven in a 21-day experiment conducted to assess the response of juvenile Monosex Nile tilapia Oreochromis niloticus with four iso-nitrogenous formulated diets: One control diet was formulated based on fishmeal, one on soybean meal and one on rice bran, ipil ipil leafmeal wasalso included in experimental diets.
  • Preliminary study on the natural extenders for artificial breeding of African catfish Clarias gariepinus (Burchell, 1822)

    Muchlisin, Z.A; Siti-Azizah, M.N. (2010)
    AACL Bioflux
    The objective of the present study was to determine the most suitable extender and theirrespective dilution ratios for African catfish sperm for artificial induced breeding and cryopreservationpurposes. Three natural extenders were tested i.e. coconut water, sugarcane water and soybeansolutions, at three different levels of sperm to extender dilutions of 1:20, 1:30 and 1:40. While Ringersolution was used as a control Diluted sperm were fertilized with ready isolated eggs to assess thefertility and hatching rate at 0, 6 and 12 hour intervals. The results showed that the eggs hatchedapproximately 19 to 27 hours after fertilization. In general, the fertilization and hatching rates decreasedwith increasing dilution ratio. With respect to natural extenders, the coconut water showed the highestfertility and hatching rates at 1:20 dilution ratio. Therefore, coconut water at 1:20 dilution ratio was theoptimal condition for African catfish spermatozoa among the natural extenders investigated.
  • Spawning seasons of Rasbora tawarensis (Pisces: Cyprinidae) in Lake Laut Tawar, Aceh Province, Indonesia

    Muchlisin, Z.A.; Musman, Musri; Siti-Azizah, M.N. (2010)
    Reproductive Biology and Endocrinology
    Rasbora tawarensis is an endemic freshwater fish in Lake Laut Tawar, Aceh Province, Indonesia.Unfortunately, its status is regarded a critical endangered with populations decreasing in recent years. To date noinformation on the spawning activities of the fish are available. Therefore, this study provides a contribution to the. knowledge on reproductive biology of R. tawarensis especially on spawning seasons as well as basic information for conservation of the species.Monthly sampling was conducted from April 2008 to March 2009 by using selective gillnets. The gonadosomatic index, size composition and sex ratio were assessed. The gonadal development was evaluated based on macroscopic and microscopic examinations of the gonads.The gonadosomatic index (GSI) varied between 6.65 to 18.16 in female and 4.94 to 8.56 for male. GSI of thefemale R. tawarensis was higher in March, September and December indicating the onset of reproductive seasons, theGSI and oocyte size being directly correlated with gonadal development stages. Although, a greater proportion ofmature male than female was detected during the study, the sex ratio showed that the overall number of female washigher than male. The ovaries had multiple oocyte size classes at every stage of gonadal development, thus R.tawarensis can be classified as a group synchronous spawner or a fractional multiple spawner. The spawning seasons of R. tawarensis were three times a year and September being the peak of the reproductive season and the female was the predominant sex. This species is classified as a group synchronous spawner. (PDF contains 8 pages)
  • Review of the live-capture of small cetaceans in Japan.

    Kasuya, Toshio; Tobayama, Teruo; Matsui, Susumu (1984)
    Report of the International Whaling Commission

View more