scholarly journals Study of Resistance to Disturbances of the Main Types of Communication Systems on Board Military Ships Used during Interception or Search and Rescue Missions

Inventions ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 72
Author(s):  
Vasile Solcanu ◽  
Marian Gaiceanu ◽  
Georgiana Rosu
Keyword(s):  
Marine Environment ◽  
Communication Systems ◽  
Search And Rescue ◽  
High Noise ◽  
International Convention ◽  
Theoretical Methods ◽  
Noise Stability ◽  
Analog Systems ◽  
The Stability ◽  
Methods Analytical

In addition to combat missions, military ships often participate in search-and-rescue missions or interception of ships with refugees or migrants. The communication systems and modes of work that may be used during these missions will be in accordance with the International Convention for the Safety of Life at Sea (SOLAS). This paper aims to demonstrate by theoretical methods (analytical and numerical) the noise stability of communication systems using analog modulation in high-noise conditions, characteristic of the marine environment. The stability of analog systems employing amplitude (AM), frequency (FM), and phase (PM) modulations is investigated. The analyzed systems are currently under use in distress maritime communications.

scholarly journals Reliability Estimation of Reinforced Slopes to Prioritize Maintenance Actions

2021 ◽  
Vol 18 (2) ◽  
pp. 373
Author(s):  
Farshad BahooToroody ◽  
Saeed Khalaj ◽  
Leonardo Leoni ◽  
Filippo De Carlo ◽  
Gianpaolo Di Bona ◽  
...  
Keyword(s):  
Urban Areas ◽  
Evaluation Method ◽  
Likelihood Function ◽  
Reliability Estimation ◽  
Analytical Models ◽  
Geotechnical Structures ◽  
Reinforced Slopes ◽  
The Stability ◽  
Methods Analytical ◽  
Asset Managers

Geosynthetics are extensively utilized to improve the stability of geotechnical structures and slopes in urban areas. Among all existing geosynthetics, geotextiles are widely used to reinforce unstable slopes due to their capabilities in facilitating reinforcement and drainage. To reduce settlement and increase the bearing capacity and slope stability, the classical use of geotextiles in embankments has been suggested. However, several catastrophic events have been reported, including failures in slopes in the absence of geotextiles. Many researchers have studied the stability of geotextile-reinforced slopes (GRSs) by employing different methods (analytical models, numerical simulation, etc.). The presence of source-to-source uncertainty in the gathered data increases the complexity of evaluating the failure risk in GRSs since the uncertainty varies among them. Consequently, developing a sound methodology is necessary to alleviate the risk complexity. Our study sought to develop an advanced risk-based maintenance (RBM) methodology for prioritizing maintenance operations by addressing fluctuations that accompany event data. For this purpose, a hierarchical Bayesian approach (HBA) was applied to estimate the failure probabilities of GRSs. Using Markov chain Monte Carlo simulations of likelihood function and prior distribution, the HBA can incorporate the aforementioned uncertainties. The proposed method can be exploited by urban designers, asset managers, and policymakers to predict the mean time to failures, thus directly avoiding unnecessary maintenance and safety consequences. To demonstrate the application of the proposed methodology, the performance of nine reinforced slopes was considered. The results indicate that the average failure probability of the system in an hour is 2.8×10−5 during its lifespan, which shows that the proposed evaluation method is more realistic than the traditional methods.

METHOD OF INCREASING THE STABILITY OF THE INFORMATION AND COMMUNICATION NETWORK UNDER THE INFLUENCE OF THE ENEMY BASED ON THE DETERMINATION OF THE REFERENCE NETWORK VERSION

2020 ◽  
Author(s):  
С.А. БАГРЕЦОВ ◽  
Э.А. БУДАРИН ◽  
О.С. ЛАУТА ◽  
М.В. МИТРОФАНОВ
Keyword(s):  
Communication Network ◽  
Information Flow ◽  
Network Traffic ◽  
Communication Systems ◽  
Reference Network ◽  
Computing Systems ◽  
Electronic Warfare ◽  
Information And Communication ◽  
The Stability

Сетевой трафик, проходящий через современные вычислительные системы, представляет собой огромный информационный поток, который содержит сведения различной степени важности. Показана необходимость использования наиболее рациональных приемов повышения устойчивости сети в радиоэлектронной борьбе, чтобы заставить противника затрачивать больше времени на подбор новых принципов воздействия на системы связи. Network traffic passing through modern computing systems is a huge information flow, which contains information of varying degrees of importance. It is shown the necessity of using the most rational methods of increasing the stability of the network in electronic warfare to force the enemy to spend more time on selecting new principles of influence on communication systems.

scholarly journals BALLAST WATER POLLUTION RISK ASSESSMENT IN THE BLACK SEA

2021 ◽  
Vol 10 (4) ◽  
pp. 35-40
Author(s):  
Vasile RAŢᾸ ◽  
Liliana RUSU
Keyword(s):  
Risk Assessment ◽  
Black Sea ◽  
Marine Environment ◽  
Ballast Water ◽  
Safety Net ◽  
The Black Sea ◽  
Natural Food ◽  
Economic Activities ◽  
Living Organisms ◽  
The Stability

Since the emergence of humanity, the marine environment has provided a safety net in many ways, has fostered socio-economic development, creating links between states, between continents. In the same time, it represents a priority source of food for a considerable percentage of the population. The same marine environment also creates solutions to current global problems, as a potential source of sustainable energy for the future. In recent decades, the stability of this ecosystem has been  considerably shaken by the various types of pollution resulting from human activities. The Black Sea is not immune to these results from economic activities, such as the transport of goods by water, which creates the context for the migration of living organisms from one geographical region to another. The threat of ecosystems has been intensified by the process of globalization, by changing the natural food chains following the accidental introduction of non- indigenous marine life by discharging ballast water from ship tanks. Risk assessment to limit the effects of this biohazard problem is the first step in a normal regional chain of action..

scholarly journals Stability of Soliton Solutions For A PT- Symmetric NLDC Considering High-Order Dispersion and Nonlinear Effects Simultaneously

2021 ◽  
Author(s):  
Lida Safaei ◽  
Mohsen Hatami ◽  
Mahmood Borhani Zarandi
Keyword(s):  
Communication Systems ◽  
Exact Analytical Solution ◽  
Nonlinear Effects ◽  
High Order ◽  
Order Effects ◽  
Coupled Equations ◽  
Solitary Solutions ◽  
Stability And Instability ◽  
The Stability ◽  
Order Dispersion

Abstract In this paper, we analytically solve the coupled equations of a PT -Symmetric NLDC by considering high-order dispersion and nonlinear effects (Raman Scattering and self-steeping) simultaneously in normal dispersion regime. To the best of knowledge no works has been done in previous studies to decoupled these equations and obtain an exact analytical solution. The new exact bright solitary solutions are derived. In addition, to study the stability and instability of these propagated solitons in a PT -Symmetric NLDC, perturbation theory is used. Numerical methods are applied to find perturbed eigenvalues and eigenfunctions. The Stability of obtained four perturbed eigenvalues and perturbed eigenfunctions for a PT -Symmetric NLDC equations regard to high-order effects are examined. Using these results and simulating the propagation of perturbed temporal bright solitons through PT -Symmetric NLDC show that perturbed solitons are mostly stable. This means that high-order dispersion and nonlinear effects canceled each other and do not affected the propagated solitons. Furthermore, the evolution of perturbed solitons energies match well the previous results and con rmed the stability of these solitons in a PT -Symmetric NLDC. As seen the energies of pulses in bar and cross behave in two manner 1) the exchange of energy is happened in some periods, but the shape of each pulse in bar and cross is preserved. Therefore, the solitons under this eigenfunction perturbation are mostly stable. 2) the evolution of energy in the bar and cross, demonstrate that there is no changes in their energies and they remain constant. It is straightforward to show that in spite of considering high-order effects, the perturbed soliton conserve the shape and it remain stable. The deliverables of this article not only demonstrate a novel approach to ultra-fast pulses, solitons and optical couplers, but more fundamentally, they could give insight for improving the new medical equipments technologies, enabling innovations in nonlinear optics and their usage in designing new communication systems and Photonic devices.

scholarly journals Onset of Motion of Sediment underneath Scour Protection around a Monopile

2018 ◽  
Vol 6 (3) ◽  
pp. 100 ◽  
Author(s):  
Anders Nielsen ◽  
Thor Petersen
Keyword(s):  
Thin Layer ◽  
Marine Environment ◽  
Current Flow ◽  
Failure Mechanisms ◽  
Offshore Wind ◽  
Incipient Motion ◽  
Offshore Wind Turbines ◽  
Clear View ◽  
The Stability ◽  
Scour Protection

The stability of scour protections is, potentially, an important issue during the design of fixed foundations for offshore wind turbines. One of the failure mechanisms observed at placed scour protection around offshore foundations is suction of sediment through the scour protection and subsequent sinking of the scour protection. Incipient motion of sediment and the initiation of suction underneath scour protections around piles in the marine environment were studied under waves, current and combined waves and current conditions. The motion of a thin layer of sediment underneath the scour protection was studied through the glass bottom of the test flume, which provided a clear view of the initiation of the motion of the sediment. The results show that the mobility depends on the Keulegan–Carpenter ( K C ) number for the pile, the ratio between waves and current flow and the ratio between the thickness of the scour protection and the base sediment. The critical mobility number is smaller for the wave-dominated situation compared to current-dominated conditions, which again are smaller than for combined waves and current conditions. Consequently, larger K C -numbers cause larger critical mobility numbers than smaller K C -numbers. Design diagrams are presented for the threshold of incipient motion of sediment underneath a scour protection in waves, current and combined waves and current.

scholarly journals Cry-wolf signals emerging from coevolutionary feedbacks in a tritrophic system

2015 ◽  
Vol 282 (1818) ◽  
pp. 20152169 ◽  
Author(s):  
Atsushi Yamauchi ◽  
Minus van Baalen ◽  
Yutaka Kobayashi ◽  
Junji Takabayashi ◽  
Kaori Shiojiri ◽  
...  
Keyword(s):  
Communication Systems ◽  
Feedback Loops ◽  
Tritrophic System ◽  
Evolution Of Communication ◽  
Herbivore Induced Plant Volatiles ◽  
Plant Signals ◽  
Selection For ◽  
The Stability ◽  
Plant Herbivore ◽  
Heavy Damage

For a communication system to be stable, senders should convey honest information. Providing dishonest information, however, can be advantageous to senders, which imposes a constraint on the evolution of communication systems. Beyond single populations and bitrophic systems, one may ask whether stable communication systems can evolve in multitrophic systems. Consider cross-species signalling where herbivore-induced plant volatiles (HIPVs) attract predators to reduce the damage from arthropod herbivores. Such plant signals may be honest and help predators to identify profitable prey/plant types via HIPV composition and to assess prey density via the amount of HIPVs. There could be selection for dishonest signals that attract predators for protection from possible future herbivory. Recently, we described a case in which plants release a fixed, high amount of HIPVs independent of herbivore load, adopting what we labelled a ‘cry-wolf’ strategy. To understand when such signals evolve, we model coevolutionary interactions between plants, herbivores and predators, and show that both ‘honest’ and ‘cry-wolf’ types can emerge, depending on the assumed plant–herbivore encounter rates and herbivore population density. It is suggested that the ‘cry-wolf’ strategy may have evolved to reduce the risk of heavy damage in the future. Our model suggests that eco-evolutionary feedback loops involving a third species may have important consequences for the stability of this outcome.

Selected aspects of modelling the system on the example of search and rescue service

2018 ◽  
Vol 120 ◽  
pp. 39-48
Author(s):  
Norbert Chamier-Gliszczyński ◽  
Jerzy Fiuk
Keyword(s):  
Search And Rescue ◽  
Operating Costs ◽  
System Model ◽  
Time Of Arrival ◽  
International Convention ◽  
Rescue Service ◽  
Full Analysis ◽  
Maritime Search And Rescue

The article is an attempt to present the aspect of modelling the system on the example of air maritime rescue interpreted as SAR service (Search and Rescue). The necessity and need for the existence of the SAR service results from the International Convention on Maritime Search and Rescue signed by Poland. An important element of the structure of the SAR service are its individual elements (eg. location of air bases, etc.). The time of arrival in places far away from the currently existing SAR air service bases is so significant that it may cause the failure of the action. The question arises whether increasing the number of airbases gives a chance to reduce the system's operating costs, increase its efficiency and thereby raise the level of safety at sea and in the area of responsibility of the SAR service. For the full analysis of the functioning of the SAR service it is necessary to undertake optimization studies. Due to the complexity of the SAR service, it should be considered in systemic categories. Authors interpreting aviation SAR service in the form of a system whose mapping is the SAR system model undertakes research aimed at optimizing the operation of this service.

scholarly journals Design of a Linear LNA for 5G Applications using 45 nm Technology

2021 ◽  
Vol 20 ◽  
pp. 128-132
Author(s):  
Rashmi Hazarika ◽  
Manash Pratim Sharma
Keyword(s):  
Communication Systems ◽  
Noise Figure ◽  
Low Noise ◽  
Active Inductor ◽  
Output Stage ◽  
Common Gate ◽  
Noise Amplifier ◽  
Cost Efficient ◽  
The Stability ◽  
Gate Input

A low noise amplifier (LNA) plays a very significant role in communication systems. Despite having a good amplification of the signal it must offer other attributes like noise figure, linearity etc for making the communication system more robust. With the advent of 5G communication, the requirement of a high BW LNA is becoming important. This paper presents the design of a LNA which have a common gate input configuration, an active inductor in place of a passive inductor, common drain amplifier at the output stage and a linearity circuit. Common gate amplifier offers a good voltage amplification while the common drain stage enhances the stability. The active inductor facilitates reduction of the die area paving the way for a cost efficient structure. This proposed design achieves a gain of 15.17dB with substantial enhancement of linearity. A good noise figure of 7dB is obtained while using 11 transistors and eliminating the need of passive inductors. The peak gain is achieved at 3.5GHz

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