Meander Type Research Articles

PERTURBATION IN MEANDER BEHAVIOUR OF A SUBTROPICAL RIVER IN INDIA UNDER VARIABLE NATURAL AND ANTHROPOGENIC CONTROLS

Meander morphology is perturbed worldwide by human interventions to a certain extent in the Anthropocene. To this end, the present study aims to investigate the meander behaviour, including its deformations, of the Kopai River, a subtropical river in India in the last 50 years (1970-2020). A total of 394 loops (134 loops each in 1970 and 1995 and 126 loops in 2020) were selected for the four river reaches – the upper, middle-upper, middle-lower, and lower reaches. The meandering behaviour was assessed using Mueller’s sinuosity index (SI), meander form index, meander shape index, and radius/wavelength ratio. The study found a higher meandering tendency in the lower and upper reaches controlled by fluvial hydraulics, and topographic factors. However, the middle reaches were comparatively stable. The meander loops along the middle reaches regular meander is the dominant meander type, however, more than 50% of meander loops for the lower reaches were intense meander types. Positive extensions were the predominant type of meander deformation in all the reaches. However, few negative extensions are found in the middle-upper and lower reaches, while irregular changes and cut-offs were only found in the lower reach. Thus, the upper and lower reaches exhibited more natural controls dotted with regular meander progression. The middle reaches characterized by higher Bouguer anomaly and steep basement gradient led to channel confinement. Besides, profuse sand mining and the brick kiln industries are perturbing the meander beahviour through human channel straightening, dwarfing the meander evolution in the middle reaches.

Monitoring of Channel Deformations of the Lower Dniester Using Topographic Maps and Satellite Imagery with the Implementation of GIS Technologies

Rivers are one of the most complex formations on the Earth’s surface; they are connected with the deep structure of the Earth, the landscape environment, and unpredictable weather cataclysms. The study aims to investigate the peculiarities of the geological structure and tectonics of the Lower Dniester region, examine the types of meanders, determine the horizontal displacements of the riverbed, and assess the impact of anthropogenic factors on the riverbed and riparian areas. The methodology is based on the use of tectonic maps, geological maps of Quaternary deposits, historical topographic maps, and satellite images to determine the long-term horizontal displacements of the riverbed, identify meander types, and study the meandering characteristics and their relationships with tectonic structures. Horizontal riverbed displacements were measured at 76 points using data from the 1980 map and a Sentinel-2 image obtained in 2020. For the purpose of studying the types of meanders and their analysis, it is proposed to use the characteristics of meanders and their relationships. This approach will allow for more efficient analysis and prediction of changes in channel processes under the influence of natural and anthropogenic factors across various temporal scales. The research shows that the Lower Dniester region is influenced by the tectonics of internal structures and the seismically active Vrancea zone in Romania. Additionally, a comparison of cartographic data from 1880 and 1980 and satellite images from 2020 allows us to assess how the territory of the Lower Dniester riparian area has changed under the influence of anthropogenic factors.

RELIEF AND GEOLOGICAL STRUCTURE OF REGIONAL LANDSCAPE PARKS “PRYTYSIANSKYI” AND “CHERNIVETSKYI”

Eight regional landscape parks (RLP) are located on the territory of the Ukrainian Carpathians, which play an important role in relief and natural complexes protecting within the region. RLP significantly complements the nature protection functions of two nature reserves and 13 national parks in the Ukrainian Carpathians. Six RLPs are located in the mountainous part of the region, and regional landscape parks "Prytisyanskyi" and "Chernivetskyi" are within the premountain uplands, the natural complexes of which are insufficiently protected. Within the boundaries of the Precarpathian Upland there are sections of two national nature parks such as Halytskyi and Hutsulshchyna. There are no nature reserves or national nature parks within the Zakarpattia (Transcarpathian) Plain. Regional landscape parks "Prytisyanskyi" and "Chernivetskyi" due to the cluster structure of the territories significantly improve the state of protection of premountain natural complexes. In the relief of the southern section of RLP "Prytisyanskyi", the dominant position covers by the low and high floodplains, less often by the first floodplain terrace of the Tysa River. The relief of the northern part of the park is represented by low and high floodplains, fragments of the first floodplain terrace. A complex of different types of meanders is observed in the channel of Latoritsa River. RLP "Prytisyanskyi" fairly fully represents the features of the geological structure and fluvial relief of the Uzhgorod-Beregivska and Vylok-Korolevska alluvial plains of the Zakarpattia (Transcarpathian) Plain with island volcanic hills. Most of the territory of RLP "Chernivetskyi" on the west and south from Chernivtsi city covers by Chernivtsi Upland with a layered and hilly sculptural relief and Mount Tsetsyna (537 m). The park includes separate sections of low terraces along the Prut River. The northern part of the RLP is represented by the Khotyn Upland with Mount Berda (516 m) as the highest point of the Ukraine’s plain part within the East European Platform. The Khotyn Upland is an asymmetric hilly plateau. Its the highest peaks are formed by structural surfaces with steep slopes. The lower level of relief in the RLP is represented by watersheds with karst forms (karst funnels, polje). RLP "Chernivetskyi" represents the geological and geomorphological structure of the Chernivtsi-Storozhynetsky strand-hilly upland of the Pokut-Bukovinsk-Peredkarpattian stratum-denudation-accumulative Upland, as well as the Khotyn structural Upland of the Prut-Dnister stratum-wave Plain. Keywords: Regional landscape park; RLP "Prytisyanskyi"; RLP "Chernivetskyi"; Ukrainian Carpathians; relief.

Line spacing effect on the giant magnetoimpedance behavior on microribbon with meander type: a comparison of theory and experiment

Purpose Microribbon with meander type based on giant magnetoimpedance (GMI) effect has become a research hot spot due to their higher sensitivity and spatial resolution. The purpose of this paper is to further optimize the line spacing to improve the performance of meanders for sensor application. Design/methodology/approach The model of GMI effect of microribbon with meander type is established. The effect of line spacing (Ls) on GMI behavior in meanders is analyzed systematically. Findings Comparison of theory and experiment indicates that decreasing the line spacing increases the negative mutual inductance and a consequent increase in the GMI effect. The maximum value of the GMI ratio increases from 69% to 91.8% (simulation results) and 16.9% to 51.4% (experimental results) when the line spacing is reduced from 400 to 50 µm. The contribution of line spacing versus line width to the GMI ratio of microribbon with meander type was contrasted. This behavior of the GMI ratio is dominated by the overall negative contribution of the mutual inductance. Originality/value This paper explores the effect of line spacing on the GMI ratio of meander type by comparing the simulation results with the experimental results. The superior line spacing is found in the identical sensing area. The findings will contribute to the design of high-performance micropatterned ribbon with meander-type GMI sensors and the establishment of a ribbon-based magnetic-sensitive biosensing system.

Characterization of the microstructure, texture, and tensile behavior of additively manufactured Hastelloy X superalloy: Insights into heat treatment at 900 °C

This research aimed at the microstructural characterization and elucidation of room- and high-temperature tensile properties of additively manufactured Hastelloy X Ni-based superalloy heat-treated at 900 °C. The samples were fabricated via the laser powder bed fusion method utilizing two scan strategies known as island and meander types. The results indicated that the cellular structure embedded in the columnar grains of the as-built microstructure disappeared after applying the heat treatment, linking to the reduction in dislocation density while keeping the former morphology of the grains unchanged. However, the intensities of the Brass, Goss, Goss-Brass, and rotated Goss texture components were reduced, leading to the generation of more homogenous fibers in the heat-treated microstructure. Additionally, it caused the formation of a Mo-rich phase on the grain boundaries, which improved the room temperature's ultimate tensile strength. However, it was elucidated that the Mo-rich phase-induced void formation and intergranular cracking failure caused a slight decrease in hot ductility. Overall, the obtained results revealed that the heat-treated island samples showed superior hot tensile behavior than the meander sample due to having a larger grain size.

Energetic material characterization and ignition study of MEMS based micro-thruster for multi spacecrafts missions

Over the past few years, there has been a growing recognition of the importance of multi-spacecraft missions for a variety of purposes, including Earth observation, navigation, guidance, climate monitoring, and environmental monitoring. The trend amongst agencies is to favour constellations of smaller satellites, which can aggregate data from various sources, rather than relying on larger satellites. The numerous benefits of multi-spacecraft formation flying missions have led to an increasingly growing interest to explore its propulsion technologies, i.e., micro propulsion. Thoroughly characterising and studying the behaviour of the energetic materials is essential to ensure the safe and effective use of these micro-thrusters. Through the optimisation of micro-thruster design, the current research aims to generate outcomes that can be utilised to enhance the design and optimisation processes. Consequently, this will facilitate the widespread utilisation of micro-thrusters in multi-spacecraft missions. To optimise the performance of pyrotechnic micro-electromechanical systems, an efficient heater design, appropriate base material, channel dimensions, and electrical resistance must be considered based on available power and heat transfer requirements. A unique firing and monitoring test setup has been developed to produce a current-time plot for the device. Additionally, different micro-heater configurations, including spiral, loop, and meander types, were designed for the igniter. Experimental observations indicate that the spiral micro-heater design resulted in the lowest ignition delay and produced highly reliable combustion. The proposed microthruster design demonstrated efficient combustion and yielded promising results when tested with energetic materials such as Zirconium Potassium Perchlorate (ZPP) and Boron Potassium Perchlorate (BPN).

Simple Dual-Feed Dual-Circular Polarization Antenna with High Isolation

A dual-feed antenna system with circular polarization (CP) diversity and high isolation is proposed in this paper. The proposed antenna consists of two bent monopole antennas and an isosceles triangular partial GND on a single layer. To simply design an antenna with dual-feed dual-CP characteristics, CP bandwidth (BW) is optimized based on a single antenna. The proposed antenna is structurally different from conventional antennas in three ways. Structural asymmetry is realized by bending the shape of the antenna and moving the position, and thus good CP characteristics are obtained. The feeding structure is changed from a linear type to a meander type. As a result, a single monopole antenna has a CP BW of 36%. Next, an antenna system with dual-CP characteristics is introduced by implementing two monopole antennas on a single layer. In this structure, the resonant frequency is controlled by the antenna geometrical parameters, and the null frequency at S21 is controlled by the distance between the two antennas. The measured results show that the CP BW of the proposed antenna is 40.6% (1.51–2.28 GHz). The measured isolation is below -20 dB within the operating BW.

Techno ‐economic analysis of Al 2 O 3 / CuO nanofluid applied in various horizontal ground heat exchangers

A ground source heat pump (GSHP) is widely regarded as a promising technology for building heating, ventilation, and air conditioning because of its higher energy efficiency. Nanofluids (NFs) have also received extensive attention due to their excellent heat transfer characteristics. In this paper, CuO/Al2O3 particles mixed with propylene glycol/water (PG/W, volume ratio: 60/40) are applied to GSHPs as a heat transfer medium. The combination of different pipe types and different concentrations of NFs is studied by comparing the coefficient of performances (COPs) and outlet temperatures. The results show that the 2% CuO NF combined with the spiral type offers the best performance with a 28% rise in the outlet temperature in the pipe and an average COP value of 4.6. When the concentration of Al2O3 NF is 2%, the combined effect of the meander type is the best. The optimal combination of CuO (2%) and spiral type is used for economic analysis by comparing with the performance of natural gas boilers, air source pumps, and GSHPs under similar conditions. The levelized cost of heat analysis results indicate that the horizontal GSHP system coupled with NF can maximize heat exchange efficiency and mitigate environmental effects, but the cost is still high as ¥ 1355/MWh ($212.46/MWh).

Electromechanical modelling and stress analysis of RF MEMS capacitive shunt switch

This paper presents the simulation results as well as calculated results of a proposed RF MEMS shunt switch with Electro-mechanical modelling and stress gradient characteristics. The analysis is done with three membrane structures such as plane beam, incorporated with and without perforations, and non-uniform meander type beam, these are simulated in the COMSOL Multi-physics tool. The various model analysis are carried out for different values of residual stress gradients such as different structures, materials, and beam thickness. The analysis are characterized that the higher values of stress gradient are not desirable for switching action. By analyzing all the results we have observed that the stress analysis for the non-uniform meandered type switch obtained maximum stress of 35.6 MPa, and center deflection of 0.06 MPa/μm, the deformations of the beam which is the least among the considered switches.

Drainage Patterns and River Sinuosity in Padang, West Sumatra

Padang City is the capital of West Sumatra Province. This city has several rivers, each of which is a watershed. Watershed management can be done through geomorphological analysis by taking a landscape approach to finding out the tectonics working in the area. The morphotectonic analysis carried out in this study was an analysis of the drainage pattern and the river's sinuosity. The purpose of this study was to determine the characteristics of the watershed in the Padang City associated with tectonic activity based on morphometric analysis. The parameters used are the drainage pattern and the river sinuosity index. The results of the research that has been carried out, it is found that the genetic types of rivers found in the Padang City, West Sumatra are dendritic, trellis, and parallel types. Meanwhile, after analyzing the average value of the sinuosity index on river flows in Padang City, it was obtained a value of 1.56 or categorized as a meandering river type with active tectonics. The results of this study can be used as new information in watershed management in Padang City, West Sumatra Province.

Quantitative, Temperature-Calibrated and Real-Time Glucose Biosensor Based on Symmetrical-Meandering-Type Resistor and Intertwined Capacitor Structure.

Here, we propose a glucose biosensor with the advantages of quantification, excellent linearity, temperature-calibration function, and real-time detection based on a resistor and capacitor, in which the resistor works as a temperature sensor and the capacitor works as a biosensor. The resistor has a symmetrical meandering type structure that increases the contact area, leading to variations in resistance and effective temperature monitoring of a glucose solution. The capacitor is designed with an intertwined structure that fully contacts the glucose solution, so that capacitance is sensitively varied, and high sensitivity monitoring can be realized. Moreover, a polydimethylsiloxane microfluidic channel is applied to achieve a fixed shape, a fixed point, and quantitative measurements, which can eliminate influences caused by fluidity, shape, and thickness of the glucose sample. The glucose solution in a temperature range of 25–100 °C is measured with variations of 0.2716 Ω/°C and a linearity response of 0.9993, ensuring that the capacitor sensor can have reference temperature information before detecting the glucose concentration, achieving the purpose of temperature calibration. The proposed capacitor-based biosensor demonstrates sensitivities of 0.413 nF/mg·dL−1, 0.048 nF/mg·dL−1, and 0.011 pF/mg·dL−1; linearity responses of 0.96039, 0.91547, and 0.97835; and response times less than 1 second, respectively, at DC, 1 kHz, and 1 MHz for a glucose solution with a concentration range of 25–1000 mg/dL.

Design and Analysis of Novel RF-MEMS Capacitive Type Shunt Switch for 5G Applications

This paper presents the design and analysis of the RF-MEMS Capacitive type switch. Here, we have proposed different stages of shunt switches for better performance. The objective of the proposed work is to design different beam structures and to calculate pull-in voltage with various gaps, beam thickness, and materials in FEM tool. By decreasing the pull-in voltage we have taken perforations and different meandering techniques (uniform and non-uniform). The material selection impacts the switch performance, here the dielectric material is taken as silicon nitride, the beam material is considered as gold, because of its high conducting material. The pull-in voltage of the proposed non-uniform meander type switch is 1.9 V, the RF-performance is measured in the HFSS and ADS equivalent circuit simulator tools, the return and insertion losses are obtained as −41.74 dB and -0.95 dB at 43 GHz, 40.10 GHz. The switch measured better isolation as – 36.25 dB, -20.55 dB at 20-40 GHz. The switch performance is obtained at 20-50 GHz range, therefore it can be feasible for 5G applications.

Geometry of Ancient Mazes: A Synthesis Part II: ‘Roman’ Mazes

The aim of the present survey was an investigation of the processes implemented for conceiving and setting up three types of ancient mazes which have come down to us on various media (stone, mosaic, painting, ceramic, coins…) from Prehistory to Middle Ages (and, for some, even later). The first part of this study was devoted to the so-called ‘Cretan’ mazes, and this second part focusses on a corpus of 43 ‘Roman’ mazes ranging from Portugal and England to Cyprus and from 100 BC to AD 330. Like the other one, this type is well individualized and homogeneous; it is characterized by several similar sectors run through, clockwise or anticlockwise. An introductory study of a maze exemplifies the fundamental duality between path and walls and the various types of meanders which are to be met with. Then a general processes for setting up a Roman maze, beginning with making a regular grid, going on with filling a sector and duplicating it and ending with managing an entrance/exit device, is proposed. Variants of the general prototype are also reviewed. In particular, in the course of this work a comparative study enabled to investigate the complex and intriguing maze of Pula (Croatia), the structure of which can now be better understood.

Performance analysis of EBG bandstop filter using U: shaped meander type electrostatically actuated RF MEMS switch

Now a days, filters became essential component in many of the RF, satellites and wireless communication networks and system. The size and complexity of the system increases while dealing with multiple frequencies which employs a large number of filters. Hence, a single filter which can reconfigure at multiple frequencies is much more needed in the present scenario. In this paper, a reconfigurable band stop filter is designed by integrating RF MEMS switch. The proposed switch is modelled with U—shaped meanders which offers low spring constant of 1.54 N/m to reduce the Pull—in—voltage to 5.2 V. The suspended beam in the switch is actuated to reconfigure the frequency of the filter by varying the capacitance from upstate to down state. The reconfiguration in the frequency of filter is observed from 16.36 to 12.34 GHz showing good isolation of – 22.7 dB at 16.36 GHz and − 36.85 dB at 12.34 GHz. The analysis in the paper is carried out using COMSOL and HFSS FEM tools to understand the electromechanical and electromagnetic characteristics of both switch and Filter for Ku-band frequency application.

Active identification of object parameters with non-scalar inputs-outputs

In this work, within the framework of the active identification problem, the recurrent least squares method is used to determine the object parameters with non-scalar signals at the input and output of the system. The proposed technique is shown using the example of a third order object. Calculations are executed in Simulink environment. Parameter estimates are received for a discrete description of a third-order object as a result of modeling in Simulink environment. Convergence graphs of parameter estimates to the base values of the in question object are given. It should be noted the rapid convergence of parameter estimates. A meander type signal was used to test the proposed parameter estimation algorithm.

Projeto de uma Antena Planar Dipolo Curvado para Aplicação na Comunicação da Indústria 4.0

This article contemplates a qualitative analysis of the operation of a Curved Planar Dipole Antenna, of the line meander type and its applicability in the Internet of Things (IoT). Technology originated in the midst of the intelligent technological development of the current period, considered as the Fourth Industrial Revolution or Industry 4.0 and marked by the improvement of systems that promote automation of tasks, control and data sharing in wireless networks in real time. IoT is associated with facilitated connectivity between the physical and digital world through the internet or miniaturized elements, generating optimization in the manufacturing and routine processes. Particularly, planar antennas stand out in this regard, as they provide the transmission or reception of signals by means of electromagnetic waves, have low manufacturing cost, small volume and weight and are built according to the desired purpose. Thus, the proposed objective was to design, simulate and analyze a meander line antenna that operates in the 2.4GHz ISM (Industrial, Scientific and Medical) frequency range, verifying its effectiveness in the IoT. However, with the aid of the HFSS® software, satisfactory results regarding the resonance frequency and radiation diagram of the studied device are obtained in a computer simulation environment.

Anastomosing-to-meandering transitional river in sedimentary record: A case study from the Neogene of central Poland

We present a sedimentological analysis of the Wielkopolska Member, the upper unit of the Poznań Formation which formed in a fluvial environment within a tectonic graben during the middle Miocene to early Pliocene in Poland. Large excavations in a lignite opencast mine have enabled our study of palaeochannel infills, in which sandy to silty-clayey ribbons are scattered within overbank clays. Channel sedimentation was controlled mainly by silty-clayey suspension settling and counter point bar accretion, with sinuous dunes and cut-and-fill of scours as secondary depositional agents. Lithofacies frequency indicates that the channel facies derived from both fine-grained suspension and bedload. The river was low energy, with the power of flood flows calculated in the range of 2.5 to 21 W m−2. Washload concentration was high, as demonstrated by thick silty-clayey packages within palaeochannels, the presence of climbing dunes and the relatively low number of ripple-derived beds. Alluvial channels were deep and narrow (3–4 m and 70–90 m for main channels; 2–3 m and <30 m for secondary channels, respectively). The average width to depth (w/d) ratio approaches 13. This value indicates that lateral channel migration was limited. Some palaeochannel successions consist of thin basal sandy bed overlain by thick silty-clayey interval. They prove an abrupt channel abandonment, that is, avulsion. Avulsion often occurred as channel reoccupation, as is evidenced by the frequent superposition of two or three ribbons. The interpreted environmental features suggest that the fluvial system was transitional between an anastomosing and a meandering river. This transitional nature was most likely due to climatic and tectonic conditions. During the deposition of the sediments studied, slow regional subsidence occurred together with the general trend for cooling and drying climate with its clear seasonality. At that time, the deposition in the anastomosing river prevailed, while in periods of limited subsidence and increased rainfall the river transformed into a meandering type. This study provides new facts about sedimentary successions of low-energy rivers, and broadens the discussion on the evolution of ancient fluvial systems.

Highly sensitive wide range linear integrated temperature compensated humidity sensors fabricated using Electrohydrodynamic printing and electrospray deposition

Percentage relative humidity is dependent on environmental temperature but the fact is ignored in most of research on humidity sensors. Secondly, the physical size of sensors should be small enough to enable integration on a commercial microchip. In this work, an integrated micro temperature plus humidity sensor system is presented that compensates for the effect of surrounding temperature on the output resistance of humidity sensor. The sensors were fabricated using Electrohydrodynamic drop-on-demand (EHD-DOD) printing for the electrodes, and Electrospray deposition (ESD) for active layer fabrication of humidity sensors. Electrode line widths were 10 μm while the combined area of both sensors was ∼2 mm2. Meander type silver patterns were used as resistive temperature sensors and interdigitated transducer (IDT) electrodes were used for humidity sensors. The active layer of humidity sensors was fabricated using a novel composite of Polyethylene Oxide (PEO) and 2D Molybdenum disulfide (MoS2) flakes to achieve a highly sensitive (85 kΩ/%RH) and almost linear response for a wide detection range (0–80% RH) of relative humidity. A mathematical model relating the outputs of both sensors was developed to compensate for the effects of temperature. The system presents optimal solution for commercialization ready temperature compensated integrated micro temperature and humidity sensors fabricated through all printing techniques.

Effects of parallel and meander configuration on thin-film magnetoimpedance element

We investigated the effects of configuration of thin-film magnetoimpedance element on impedance profile. The parallel type and meander type sensor element were fabricated. The parallel line configuration has advantages to reduce a bias field and to enhance total inductance attributable to positive mutual inductance, while a large number of lines brings a decrement of impedance changes. The meander type induces a large demagnetizing effect and decrement of the total inductance due to negative mutual inductance. However, this configuration can utilize the space of the element, which contributes to enhance spatial resolution.

Особенности пироэффекта в эпитаксиальных слоях нитрида алюминия, полученных на Si-подложках

The pyroeffect was studied in quasi-bulk AlN layers with a thickness of 10-170 μm obtained by the technology of chloride-hydride vapor phase epitaxy on standard Si sub-strates. The pyroelectric current was measured by the method of thermal exposure to non-stationary (me-ander type) laser radiation, that together with the data of independent non-contact measure-ment of the active layer surface temperature dynamics made it possible to determine the value of the pyroelectric coefficient AlN in the composition of the bimorph AlN / Si structure for different thicknesses of AlN layers. It was found that the mean values are less than those that correspond to the material obtained by the same technology, but on SiC substrates; so, in or-der to achieve the pyrocoefficients of comparable magnitude with those in the case of “AlN on Si”, an increase in the thickness of AlN layers by 60 -70% is re-quired. At the same time, when the thickness of the AlN layer is large (110 μm, 170 μm) after the removal of the silicon substrate, the pyroelectric coefficient increased and reached ~8.6-9.0μC/(m2·K).