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In this study, the dynamics of the tendon/top tension riser (TTR) system of a tension-leg platform (TLP) are investigated through an experiment and by using absolute nodal coordinate formulation (ANCF). First, the model test of the TLP system is conducted in the water tank of Harbin Engineering University to examine the motion response of the TLP and the dynamic response characteristics of the tendon and TTR. The test scale ratio is set to 1: 66.3. Then, on the basis of the ANCF, the stiffness, external load, and mass matrices of the element are deduced to establish the motion equation of the tendon/riser. Finally, the static and dynamic characteristics of the tendon/TTR system of TLP are analyzed systematically by using the ANCF method. The results are compared with commercial software and test results. The motion response of tendon/TTR is affected by the TLP movement and environmental load simultaneously. The analysis proves the effectiveness and accuracy of the ANCF method despite the low number of riser units, suggesting the superiority of the ANCF method for calculating the dynamics of tendon/riser in the field of ocean engineering.

In this paper, the dynamics of the flexible riser are investigated based on the absolute nodal coordinate formulation (ANCF). The stiffness, generalized elastic force, external load, and mass matrixes of the element are deduced based on the principle of energy conversion and assembled with the finite element method. The motion equation of the flexible riser is established. The influence of the environmental load conditions on the flexible riser model is studied in the MATLAB environment. Moreover, the accuracy and reliability of the programs are verified for a beam model with theoretical solutions. Finally, the static and dynamic characteristics of the flexible riser are analyzed, systematically adopting the ANCF method, which in turn proves the effectiveness and feasibility of the ANCF. Therefore, the proposed method is a powerful scheme for investigating the dynamics of flexible structures with large deformation in ocean engineering.

In the present study, the dynamics of the tendon system of a tension-leg platform (TLP) is investigated through the absolute nodal coordinate formulation (ANCF). Based on the energy conversion principle, the stiffness, generalized elastic force, external load and mass matrices of the element are deduced to perform the element assembling by using the finite element method. Then the motion equation of the tendon/riser is established. In this study, the TLP in the International Ship Structures Committee (ISSC) model under the first and second wave forces is considered as the case study. The simulation is performed in the MATLAB environment. Moreover, the accuracy and reliability of the programs are verified for cases of beam model with theoretical solutions. It is found that the motion response of tendons is affected by the TLP movement and environmental load, simultaneously. Then, the motion response is calculated using the SESAM software and exported as the boundary of ANCF tendons. Finally, the static and dynamic characteristics of the four tendons of ISSC TLP are analyzed systematically by the ANCF method. Performed analysis proves the effectiveness and feasibility of the ANCF method. It is concluded that the proposed method is a powerful scheme for calculating the dynamics of tendon/riser in the field of ocean engineering.

We introduce a novel tree coloring problem in which each node of a rooted tree of height $h$ is assigned one of the $h$ colors under the condition that any two nodes that are ancestor and descendant of each other must have different colors and moreover, the numbers of nodes in any two distinct color classes differ by at most one. We refer to such a coloring as a balanced ancestral coloring. Our key contribution is to characterize, based on majorizations, all color sequences (not only the balanced ones) for which there exists an ancestral coloring for perfect binary trees. We then develop an almost linear time (in the number of tree nodes) divide-and-conquer algorithm to generate such a coloring for every perfect binary tree of height $h\geq 1$. The existence of a balanced ancestral coloring reveals an interesting fact about combinatorial batch code: when the batch follows a special pattern (consisting of nodes along a root-to-leaf path in a tree), the total storage capacity required can be reduced by a factor of $\Theta(h)$ compared to when the batch is arbitrary while keeping a balanced storage capacity across $h$ servers. Furthermore, our result also identifies an infinite family of graphs for which the equitable chromatic number can be explicitly determined. As far as we know, this family has not been discovered before in the literature. As a practical application, we show that a balanced ancestral coloring can be employed to speed up the private retrieval of a Merkle proof in a Merkle tree by a factor of $\Theta(h/2)$ compared to a straightforward parallel implementation of SealPIR, a state-of-the-art private information retrieval scheme., Comment: 29 pages

From a General point of view, let's consider a miniature power divider. The use of artificial transmission lines for marine applications allows you to reduce the overall dimensions and obtain a layout with reproducible dimensions. Models of a conventional and compact coupler with a Central frequency of 0.9 GHz were obtained. The area of the compact is 77.5% less than the area of a conventional power divider. The resulting device can be used in various systems where small dimensions are required.

Artificial transmission lines, together with bends of lines, are widely used in miniaturization of microwave devices for maritime communications equipment. An important class of reciprocal four arm devices is formed by directional couplers. In such devices, power is transferred from one shoulder to the other two, and the fourth shoulder remains unexcited. Thanks to artificial lines in operation, it was possible to reduce the dimensions of the device by 68.7%, at an operating frequency of 1 GHz. The paper describes the results of a 3 dB study of a broadband coupler. The bandwidth of such a device was reduced by only 100 MHz.

Some designs of compact coupler for maritime communications equipment presented in the IEEE database are considered. In addition, a proprietary compact coupler is shown and described. The proposed design is implemented on artificial transmission lines and operates at a frequency of 0.9 GHz. It was possible to reduce the device area by 75.15% due to the fact that the artificial transmission lines were shorter than the usual transmission lines used in the construction of the coupler.

The article describes the research and development of a compact microwave power divider for marine applications operating in the frequency range 100–200 MHz. Implemented the proposed divider on the distributed elements and the substrate FR4. The simulation of the device and its frequency characteristics is performed. The topological solution for the implementation of the divider on the printed circuit board, has reduced its dimensions by 70%. Artificial transmission lines were used, which made it possible to profitably use the space inside the divider. Electrodynamic modeling showed that a compact divider has 10% narrower band than a conventional divider.

This work is devoted to the development of a miniature directional coupler with a wide passband for maritime communications equipment. Artificial transmission lines having similar characteristics with quarter-wave segments, of which the directional coupler consists, are considered. Based on the calculations, a miniature coupler was modeled. Based on the simulation results, it can be judged that a working model of the device with an area of 70% less than with a traditional design was obtained. The miniature coupler is assembled for a frequency of 0.9 GHz and has a band of 67.5%. The relevance of the development is confirmed by the increased demand for compact microwave devices.

The paper describes the miniaturization process of a coupler in marine communication systems implemented in a single layer. A comparison of the parameters of a conventional and compact coupler is given. The miniaturization of the coupler became possible due to the use of artificial transmission lines having a shorter length than quarter-wave segments. The area of the received coupler was 73.5% less than the area of the coupler in the traditional version.

The paper describes the possibility of miniaturization of a directional coupler using artificial transmission lines. Using an example of a broadband coupler with an operating frequency of 1 GHz, it is shown that using such lines it was possible to reduce the device area by 70%. Compact couplers can be used in a variety of microwave applications in marine communication at sea.

The review of existing miniaturization methods is carried out. The design of a compact broadband power divider is also proposed and its characteristics are calculated. The developed coupler can be used in marine communication systems. The proposed version of the device is technologically simple to manufacture and configure when modeling. At a frequency of 1 GHz, the device has 70% smaller area and 10% narrower frequency band. The review of methods for reducing the device area is performed.

The article considers the pros and cons of miniaturization of directional couplers operating at low frequencies. The studies were conducted on the traditionaldirectional directional couplers with a central frequency of 2 GHz, dimensions were reduced due to artificial transmission lines. It was possible to reduce the area by 45% relative to the area of the standard design. The use of artificial lines allows for a compact design along with a number of advantages, such as saving material, suppressing higher harmonics, because the lines used serve as a low-pass filter. However, disadvantages are also present, i.e. the complexity of the design process and the deterioration in the characteristics of the device.

The design of a microstrip directional response in balancing the ship’s Radio and TV distribution system; its dimensions were reduced due to the use of original cells. These elements have many elements such as inductance and capacitance, and the entire structure is smaller than a quarter-wave segment. The design of a transponder with a central frequency of 1 GHz was investigated. Coupler area reduced by 59.4%, but at the same time the number of bands was reduced, when compared with the original design.

A comparison is made of the connection options for low-impedance elements playing the role of capacitance as part of a compact structure during miniaturization of a directional coupler. Connecting a parallel capacitance via inductance made it possible to increase the degree of miniaturization, so the 2-GHz coupler provides a reduction in device area by 69%, but has a bandwidth of only 6.2%.

This paper describes a tool that allows you to quickly and easily get a compact topology of a planar microwave device. The description was based on a conventional 2 GHz coupler. The whole approach to miniaturization of the coupler is to synthesize the necessary structures. These structures consist of a combination of an inductive and capacitive element, this allows you to get similar characteristics with a conventional line, but the structure has a significantly shorter length. The installation of such structures in place of the segments and allows for the miniaturization procedure. However, of course, with miniaturization, a negative effect arises of changing the frequency characteristics, in the direction of their deterioration.

The rise and fall of mean sea level are non-uniform around the global oceans. Their long-term regional trend and variability are intimately linked to the fluctuations and changes in the climate system. In this study, geographical patterns of sea level change derived from altimetric data over the period 1993-2015 were partitioned into large-scale oscillations allied with prevailing climatic factors after an empirical orthogonal function analysis. Taking into account the El Niño–Southern Oscillation (ENSO) and the Pacific Decadal Oscillations (PDO), the sea level change deduced from the multiple regression showed a better estimate than the simple linear regression thanks to significantly larger coefficients of determination and narrower confidence intervals. Regional patterns associated with climatic factors varied greatly in different basins, notably in the eastern and western regions of the Pacific Ocean. The PDO exhibited a stronger impact on long-term spatial change in mean sea level than the ENSO in various parts of the Indian and Pacific Oceans, as well as of the subtropics and along the equator. Further improvements in the signal decomposition technique and physical understanding of the climate system are needed to better attain the signature of climatic factors on regional mean sea level., El aumento y la reducción del nivel medio del mar en los océanos del planeta no son valores uniformes. Su comportamiento a largo plazo y su variabilidad están íntimamente ligados a las fluctuaciones y cambios de los sistemas climáticos. En este estudio, los patrones de cambio del nivel del mar, derivados de datos altimétricos obtenidos en el periodo de 1993 a 2015, se dividieron en oscilaciones a gran escala y se compararon con factores climáticos prevalecientes obtenidos de un análisis de Función Ortogonal Empírica. Cuando se toman en cuenta la Oscilación Sur de El Niño (ENSO) y las Oscilaciones Decenales del Pacífico (PDO), el cambio del nivel del mar deducido de una regresión múltiple produce mejores estimaciones que una regresión linear simple al tener coeficientes de determinación con un valor más grande e intervalos de confianza con valores más estrechos. Los patrones regionales asociados con los factores climáticos variaron considerablemente para diferentes cuencas, notablemente en las regiones orientales y occidentales del océano Pacífico. Se observa que las PDO mostraron un impacto más importante en el cambio espacial a largo plazo de la media del nivel del mar que la ENSO en varias partes de los océanos Índico y Pacífico, al igual que en las regiones subtropicales y alrededor de la línea del Ecuador. Se necesitan mayores mejoras en las técnicas de descomposición de señales y entendimiento físico de los sistemas climáticos para representar más precisamente la influencia de los factores climáticos en la media del nivel regional del mar.

A study to determine how the operating frequency of the device during miniaturization depends on its efficiency and the safety of the original characteristics. It was found that the miniaturization efficiency decreases with increasing frequency. Thus, the design of compact couplers for Central frequencies from 1000 to 3000 MHz with a step of 500 MHz was studied. In this case, the dimensions in relation to the standard design were reduced by 78.8, 62.5, 46.7, 39 and 30%, respectively.

A study aimed at identifying the effect of substrate parameters such as dielectric permittivity and thickness on the characteristics of directional couplers, whose dimensions are reduced by means of compact structures. It was found that with the increase in the thickness of the substrate in a compact coupler increases the frequency band and the degree of miniaturization, and with increasing dielectric constant Vice versa.

The design of the directional coupler with reduced physical dimensions, using compact structures. The proposed coupler operates at two Central frequencies, 900 and 1900 MHz. The use of compact structures instead of quarter-wave segments made it possible to reduce the standard coupler by 67%, with minor performance degradation.