With the unique characteristics, electromagnetic launch technology is applicable to launch shipborne anti-torpedo torpedo(ATT). This paper aims to establish an analytic model to pre-evaluate the ...capture probability of the electromagnetic launched ATT. The mathematics model of the multi-stage coilgun and the trajectory of the ATT is established for analysis. The influence factors of the capture probability are analyzed respectively, including the entry point dispersion of the ATT and the position dispersion of the incoming torpedo. Adopting the advanced angle interception mode, the ATT search model is obtained according to the positional relationship, and the course error is synthetically calculated according to the differentiation of implicit function. A geometric method to calculate the integral boundaries of the probability density function is proposed, based on the relative motion of the ATT and the incoming target. To verify the proposed integral model, the digital simulation and comparison is conducted. The results reveal that the variation trends and the calculation value of the proposed analytic model are coincident with the statistic results from Monte Carlo method. And implications of the results regarding the analytic model are discussed.
Electromagnetic coil launch is an important branch of electromagnetic launch (EML) technology, which is suitable for launching anti-torpedo torpedo (ATT). This paper focuses on the EML parameters and ...the interception probability of the EML two ATTs salvo. Based on the launching model of a multi-stage coil launcher, the trajectory model of the ATT and the attacking torpedo, a calculation method for the EML two ATTs salvo parameters is proposed, with the conditions of capture and interception given reasonably. An adaptive particle swarm optimization (APSO) algorithm is proposed to calculate the optimal launching parameters, by designing the adaptive inertia weight and time-varying study factors. According to the analysis of the simulation with Monte Carlo method, EML will improve the interception probability effectively, and the interception probability is affected by the launching range. The results demonstrate good performance of the proposed APSO in calculating EML parameters for the two ATTs salvo in certain combat situation. Implications of these results are particular regarding the command and decision in the anti-torpedo combat.
•A calculation method for the EML two ATTs salvo parameters is proposed based on the conventional geometric method.•The impact of the EML launching range on the interception probability is analyzed.•An adaptive particle swarm optimization (APSO) algorithm is proposed to optimize the launching parameters.
The large variation in vertebral shape and calcification observed among elasmobranch species prevents using a single method for enhancing growth bands and reading age. Further, estimating age and ...growth parameters can be difficult or impractical when samples are incomplete due to the bycatch of a size-selective fishery. Using a single and rapid method, age readings were obtained on the vertebrae of four batoid species, namely 53 individuals of Dasyatis pastinaca, 51 of Raja asterias, 15 of Torpedo marmorata, and 55 specimens of Torpedo torpedo, from the local small-scale trammel net fishery in the coastal waters (5–20 m depth) of the Central Tyrrhenian Sea during 2019–2021. Based on these data, a statistical routine was developed to obtain multiple estimates of age and growth parameters for incomplete samples due to size-selective fishing. The acceptable agreement between and within readers (intra and inter-reader disagreement < 5%) and the rate of increase in vertebral size with body size (differently ranked across species) demonstrated the consistency of the enhancing method. The parameters estimated by the Von Bertalanffy and Gompertz growth models matched the data available in the Mediterranean Sea for the species studied, with D. pastinaca, T. torpedo, and R. asterias showing the lowest (k = 0.05–0.12), intermediate (k = 0.112–0.19), and highest (k = 0.18–0.23) growth rates, respectively, in line with the life history traits of these species. Overall, the method proved effective both in delineating band pairs in vertebrae of different species and in reliably estimating the age and growth parameters of problematic samples due to size-selective fishing. The proposed method supports the collection of comparable demographic data from other areas where similar multi-specific assemblages are bycatch of size-selective fisheries impacting potential nursery areas and other essential habitats for elasmobranchs.
The present study focused on the three species of electric rays known to occur in the Mediterranean Sea: Torpedo torpedo, Torpedo marmorata and Tetronarce nobiliana. Correct identification of ...specimens is needed to properly assess the impact of fisheries on populations and species. Unfortunately, torpedoes share high morphological similarities, boosting episodes of field misidentification. In this context, genetic data was used (1) to identify specimens caught during fishing operations, (2) to measure the diversity among and within these species, and (3) to shed light on the possible occurrence of additional hidden species in the investigated area. New and already published sequences of COI and NADH2 mitochondrial genes were analyzed, both at a small scale along the Sardinian coasts (Western Mediterranean) and at a large scale in the whole Mediterranean Sea. High levels of genetic diversity were found in Sardinian populations, being significantly different from other areas of the Eastern Mediterranean Sea due to the biotic and abiotic factors here discussed. Sardinian torpedoes can hence be indicated as priority populations/areas to be protected within the Mediterranean Sea. Moreover, sequence data confirmed that only the three species occur in the investigated area. The application of several ‘species-delimitation’ methods found evidence of cryptic species in the three species outside the Mediterranean Sea, as well as in other genera/families, suggesting the urgent need for future studies and a comprehensive revision of the order Torpediniformes for its effective conservation.
Data on the biology of Torpedo torpedo from the Ionian Sea are absent, and in the Mediterranean Sea, most of the published works focus on the reproductive biology of the species and are not recent. ...Several biological and ecological aspects of Torpedo torpedo were investigated between March and May 2019 on the coast of Sicily (Ionian Sea) between Avola and Marzamemi. Morphological (disc width-weight relationships, total length-disc width relationships), population (size-frequency distribution, sex ratio, fecundity), and ecological (habitat, diet) characteristics were studied. Stomach content analysis revealed that T. torpedo is a generalist piscivore, feeding on a wide variety of benthic and benthopelagic fish: Levin's index value (Bi) was 0.82. The analysis of the sex ratio showed a higher proportion of males vs. females. Females were, on average, larger than males. Fecundity showed a positive correlation with body size, with the smallest mature female being 14.9 cm in disc width and 24.8 cm in total length. The ovarian fecundity ranged from 3 to 20 eggs. In the study area, both adults and juveniles of the species were caught in considerable numbers with trammel nets. We also provide data from some specimens of Torpedo marmorata caught during the study period.
Multi-tracer experiments determined the accumulation from seawater of selected radioactive trace elements (Mn-54, Co-60, Zn-65, Cs-134, Am-241, Cd-109, Ag-110m, Se-75 and Cr-51) by three teleost and ...three chondrichthyan fish species to test the hypothesis that these phylogenetic groups have different bioaccumulation characteristics, based on previously established contrasts between the carcharhiniform chondrichthyan
Scyliorhinus canicula (dogfish) and the pleuronectiform teleost
Psetta maxima (turbot). Discriminant function analysis on whole body: water concentration factors (CFs) separated dogfish and turbot in two independent experiments. Classification functions grouped the perciform teleosts, seabream (
Sparus aurata) and seabass (
Dicentrarchus labrax), with turbot and grouped the chondrichthyans, undulate ray (
Raja undulata; Rajiformes) and spotted torpedo (
Torpedo marmorata; Torpediniformes), with dogfish, thus supporting our hypothesis. Hierarchical classificatory, multi-dimensional scaling and similarity analyses based on the CFs for the nine radiotracers, also separated all three teleosts (that aggregated lower in the hierarchy) from the three chondrichthyan species. The three chondrichthyans were also more diverse amongst themselves compared to the three teleosts. Particular trace elements that were more important in separating teleosts and chondrichthyans were Cs-134 that was elevated in teleosts and Zn-65 that was elevated in chondrichthyans, these differences being due to their differential rates of uptake rather than loss. Chondrichthyans were also higher in Cr-51, Co-60, Ag-110m and Am-241, whereas teleosts were higher only in Mn-54. These contrasts in bioaccumulation patterns between teleosts and chondrichthyans are interpreted in the context of both proximate causes of underlying differences in physiology and anatomy, as well as the ultimate cause of their evolutionary divergence over more than 500
million years before present (MyBP). Our results and interpretation point to the possibility that radiation exposure regimes may be influenced by phylogeny, with implications for the adequacy of the marine reference organism approach in marine environmental protection.
Sex determination and differentiation are key events in the development of either the testis or ovary in fish. Sex determination mechanisms include environmental and genetic regulation. Research on ...sex determination systems and their related genes have been implemented in the teleost species, but the amount of information about these genes in cartilaginous fish is very scarce. This paper summarizes the few available data on molecular studies and chromosome localization of specific sequences useful to discriminate between various chromosome pairs in the common torpedo, Torpedo torpedo, and in the scyliorhinid coral catshark, Atelomycterus marmoratus, species that do not have morphologically distinct sex chromosomes. In addition, recent results obtained by sequence analysis of foxl2, a female-specific gene expressed during early phases of gonadal development in interesting key-species, such as the holocephalian Callorhinchus milii, is discussed. Nevertheless, the mechanism of sex determination in cartilaginous fish remains largely unknown. Further research needs to be carried out regarding the importance of basic and applied sex determination studies in fish, including chromosomal distribution of sex-related sequences.
The reproductive biology of Torpedo torpedo (n = 535) and Torpedo marmorata (n = 385), collected in coastal waters of Latium (central Mediterranean Sea, Italy) between September 2000 and October ...2001, was studied and compared. Males and females reached a maximum length of 445 and 477 mm TL in T. torpedo and 364 and 553 mm TL in T. marmorata. Males and females of T. torpedo reached length at sexual maturity (TL sub(50%)) at similar sizes (249 mm TL and 258 mm TL respectively) whereas TL sub(50%) in females of T. marmorata was greater than that of males (312 and 251 mm TL respectively). Analysis of the gonadosomatic index (GSI) and maximum oocyte diameter (MOD) in mature females suggested that gestation lasted about 6 months in T. torpedo and 9 to 10 months in T. marmorata. Fecundity was positively correlated with length in both species and, comparing ovarian and uterine fecundity, T. torpedo had a greater reproductive potential than T. marmorata. Size at birth of T. torpedo was smaller than that of T. marmorata and embryos of the latter showed a higher rate of mass increment with size than those of T. torpedo.
Anti-torpedo torpedo (ATT) is the most effective hard kill weapon for intercepting incoming torpedoes. In order to improve the interception efficiency of anti-torpedo torpedoes, the simulation study ...of anti-torpedo torpedo interception effectiveness was carried out for the surface ship defense against incoming torpedoes combat requirements during underwater attack and defense operations. On the premise of ensuring the safety of the mine-ship, an anti-torpedo torpedo interception ballistic model is established, and the operational flow, firing model and effectiveness evaluation model of ATT are given for surface ships under the typical operation mode of incoming torpedoes. Combined with the effectiveness simulation, the influence law of ATT initial ballistic parameters and other factors on the interception efficiency is analyzed. The research results can provide methods and guidance for the development and use of ATT weapons, and also can provide useful reference and technical support for the analysis and evaluation of the operational effectiveness of torpedo defense weapons in general, which has important engineering application value.
PDF
