Status of Chinese Carp Fisheries in Tunisian Freshwater Reservoirs: Threats and Opportunities

The current paper aims to diagnose the state of fisheries of three Chinese carp species whish have been introduced in Tunisian reservoirs since 1981: (silver carp Hypophthalmichthys molitrix, herbivorous carp Ctenopharyngodon idella and bighead carp Aristichthys nobilis) and seeks to study the benefits and risks associated with their introduction. Chinese carps cannot reproduce naturally in freshwater reservoirs. Eventually, artificial breeding operations and seeding of the dams with farm-produced fry are carried out by the Technical Centre of Aquaculture every year. Statistical analyses have shown a strong correlation between the landed quantity and the number of fries stocked each year. The impact assessment showed that the risks and benefits associated with the introduction of the three species are variable. Regarding their benefits, it was clear that the herbivorous carp has provided effective and sustainable control of the extensive development of aquatic vegetation in the eutrophic reservoirs and canal systems. The value of the other two species, though, remains less obvious, particularly for the bighead carp. The consequences of their introduction on ecosystems and native species seem to be negligible, especially when the densities are low. Eventually, it seems judicious to increase the stocking of the herbivorous carp, silver carp and bighead carp in Tunisian reservoirs.

Hazard forecasting techniques implementation in crane safety instruments using a crane anemometer

Introduction. This article describes an algorithm developed by the authors for the operation of a crane anemometer that measures the gust rate and average wind speed and determines the predicted wind speed on the basis of it. The main part. The main influencing parameters and their measurement intervals are defined for the construction of the anemometer algorithm. The method of calculation of gust velocity and average wind velocity from the data of the pulse sensor of the helicopter anemometer is presented. The method of wind speed forecasting based on the construction of an extrapolation function is given.Results. An anemometer program algorithm with extended capabilities relative to existing analogues has been developed. The instrument not only captures the hazard at the moment, but also predicts its future development. On the basis of the analysis of wind dynamics studies, a table has been compiled of the levels of the determined parameters (gust rate, average speed and projected average wind speed) and the signals given to the operator of the crane. For each type of signal, the value of the removal delay is defined.Conclusions. ZAO KROS Engineering and Technical Centre has made a prototype anemometer using the principles described in this article. The device meets all requirements of the regulatory and technical documentation. Further work on the improvement of the algorithm of its work will make it possible to increase the safety of technological processes carried out with the use of elevated structures.

SOCIETY OF PETROPHYSICISTS. ONLINE-PLATFORM FOR KNOWLEDGE MANAGEMENT AND SHARING

The geology of oilfields is becoming more complex, which leads to uncertain distribution of petrophysical properties. Quality of reservoir properties prediction depends on petrophysical models and log interpretation algorithms. It is also connected with the level of expertise of each petrophysicist as well as knowledge sharing among experts and young specialists. The aim of this paper is to present Gazprom Neft Science and Technical Centre approach to development of petrophysical competences with communities of practice.

ITF report: The state of the game 2018

In order to fulfil its mission of protecting the nature of tennis and encouraging innovation and improvements, the ITF Technical Centre quantifies the parameters that describe the essence of the sport at the elite level, and thus constitute ‘the state of the game’. This annual report aims to establish how players, their equipment and the interaction between them are changing over time, to analyse the impact of these changes on the game and to contemplate the merits of any necessary counter-measures. Point length is a key metric of the nature of the game. Too many short points is generally considered unattractive. Low serve returnability can lead to short points, therefore serve returnability should be monitored and understood. Serve returnability is strongly dependent on post-bounce speed, serve angle and the proximity of the bounce to the centre serviceline or sideline. Taller players typically serve faster than shorter players and therefore generate higher post-bounce speeds, lower returnability serves and consequently more short points. The higher post-bounce speed of serves by these players can be reduced, increasing their returnability, by using a slower court and/or larger ball. A warning indicator signalling an excessive number of short points could be used to determine when regulation of equipment might be used to counteract the rise of shorter points. A more radical response would be to make the service-box narrower to increase the returnability of serves without impacting the speed of subsequent shots.

TOWARDS THE QUESTION OF SPECIALIZED FEEDS FOR TENCHES (TINCA TINCA)

The article describes the process of tench growing (male and female species removed from set gear in the Volga river in the Astrakhan region) using experimental feedstuff "T", taking into account the fact that problems with artificial growing tench ( Тinca tinca ) appear first in the process of feeding when wild sires change to artificial food. The research took place on the base of the department of aquaculture and water bioresources of Astrakhan State Technical University in innovation centre "Bioaquapark - scientific and technical centre of aquaculture" in 2015. Special feed including components of animal origin - mosquito grab and sludge worm as an effective substitute to fish flour, as well as components of vegetable origin (carrot, parsley, pumpkin, wheatgrass) for domestication of tenches are offered for the first time. Food technology has been described. The exact composition of the formula, which is being licensed at the moment, is not disclosed. Feed "T", which has undergone biological analysis and is in accordance with organoleptic and physical standards was used for feeding tench female and male species during domestication period (60 days), along with food "Coppens" (Holland). Feed efficiency was determined according to survival and daily fish growth. Growth rate of females appeared more intensive than growth rate of males fed with experimental food "T". Daily growth changed depending on the types of food: from 0.3 ("Coppens") to 0.47 (experimental food) in females, from 0.25 ("Coppens") to 0.39 (experimental food) with males. Ability to survive among tench species fed with "Coppens" and experimental food made 60% and 100%, correspondingly. Nutricion of tench species with experimental food encouraged their domestication, which allowed using tench species in further fish breeding process in order to get offspring. The project was supported by the Innovation Promotion Fund in terms of the project "Development and implementation of the technique for the steady development of aquaculture: food "TechSA".