Compound Bar Research Articles

Uncovering the hidden world of riverbed sediments: The role of sediment heterogeneity and cross-bar channel fills in the hydrogeochemical dynamics of the hyporheic zone

Groundwater-surface water interaction (hyporheic exchange) is critical in numerous hydrogeochemical processes; however, hyporheic exchange is difficult to characterize due to the various spatial (e.g., sedimentary architecture) and temporal (e.g., stage fluctuations) variables that influence it. This interdisciplinary study brings forth novel insights by integrating various methodologies including geophysical surveys, physical and chemical sediment characterization, and water chemistry analysis to explore the interplay of the numerous facets governing hyporheic zone processes within a compound bar deposit. The findings reveal distinct sedimentary facies and geochemical zones within the compound bar, driven by the sedimentary architecture. Cross-bar channel fills are identified as critical structures influencing hydrogeochemical dynamics, acting as baffles to groundwater flow and modulating nutrient transformations. Geophysical imaging and hydrogeochemical analyses highlight the complex interplay between sediment characteristics and subsurface hydraulic connectivity, emphasizing the role of sediment heterogeneity in controlling hyporheic exchange and solute mixing. The study concludes that sediment heterogeneity, particularly the presence of cross-bar channel fills, plays a pivotal role in the hydrogeochemical dynamics of the hyporheic zone. These structures significantly influence hyporheic flow paths, solute residence times, and nutrient cycling, underscoring the necessity to consider the fine-scale sedimentary architecture in models of hyporheic exchange. The findings contribute to a deeper understanding of riverine ecosystem processes, offering insights that can inform management strategies for water quality and ecological integrity.

Self-stigma of leprosy affected persons in Jaffna District

Leprosy new case detections are stagnant over the past 20 years and continue to be stigmatized in socially marginalized groups and the urban poor are less likely to seek care. There is a big gap in studies related to leprosy stigma in Sri Lanka. This study aimed to measure the stigma among leprosy affected persons in Jaffna District.This was a cross sectional descriptive study done in dermatology clinic, teaching hospital, Jaffna using all 109 leprosy patients. The validated interviewer administered questionnaire with the tool (Internalized Scale of Mental Illness (ISMI) adapted for leprosyaffected persons) was used to measure the stigma. Average of mean scores (with SD) was calculated to demonstrate the level of stigma. The level of stigma to different domains/item responses were described by presenting compound bar diagrams/charts.Mean age of the participants was 40.3±18.6yrs. Most of the participants were males (53.2%), Sri Lankan Tamils (97.2%), Hindus (77.1%), married (65.1%), from MOH Chankanai area (50.5%) and affected by MB type of leprosy (68.8%). Only 44% completed secondary education, 36.7% had no job and 32.1% were manual workers. The mean score of (ISMI) leprosy patients was 2.43 which mean high level of stigma. The response pattern to different components of ISMI was heterogeneous.

Flow depth estimates and avulsion behaviour in alluvial stratigraphy (Willwood Formation, Bighorn Basin, Wyoming, USA)

AbstractThe size and geometry of river channels play a central role in sediment transport and the character of deposition within alluvial basins across spatiotemporal scales spanning the initiation of grain movement to the filling of accommodation generated by subsidence. This study compares several different approaches to estimating palaeoflow depths from fluvial deposits in the early Palaeogene Willwood Formation of north‐west Wyoming, USA. Fluvial story heights (n = 60) and mud plug thicknesses (n = 13) are statistically indistinguishable from one another and yield palaeoflow depth estimates of 4 to 6 m. The vertical relief on bar clinoforms (n = 112) yields smaller flow depths, by a factor of ca 0.3, with the exception that the largest bar clinoforms match story heights and mud plug estimates. This observation is consistent with modern river data sets that indicate unit bar clinoforms do not capture the reach‐mean bank‐full flow depths except in rare circumstances. Future studies should use story heights (i.e. compound bar deposits) and mud plugs to estimate bank‐full flow depths in alluvial strata. Additionally, the thickness of multi‐storied fluvial sandbodies (n = 102) and overbank cycles composed of paired crevasse splay and palaeosol deposits (n = 45) were compared. The two depositional units display statistically indistinguishable mean and median values. Building upon previous depositional models, these observations suggest basin rivers aggraded approximately one flow depth prior to major avulsion. This avulsion process generated widespread crevasse splay deposition across the floodplain. Once the main river channel stem was reestablished, overbank flooding and palaeosol development dominated floodplain settings. The depositional model implies river aggradation autogenically generated topography in the basin that was effectively filled during the subsequent avulsion. This constitutes a meso‐timescale (103–104 years) compensational pattern driven by morphodynamics that may account for the high completeness of fossil and palaeoclimate records recovered from the basin.

Geophysical mapping of hyporheic processes controlled by sedimentary architecture within compound bar deposits

AbstractHyporheic exchange influences water quality and controls numerous physical, chemical, and biological processes. Despite its importance, hyporheic exchange and the associated dynamics of solute mixing are often difficult to characterize due to spatial (e.g., sedimentary heterogeneity) and temporal (e.g., river stage fluctuation) variabilities. This study coupled geophysical techniques with physical and chemical sediment analyses to map sedimentary architecture and quantify its influence on hyporheic exchange dynamics within a compound bar deposit in a gravel‐dominated river system in southwestern Ohio. Electromagnetic induction (EMI) was used to quantify variability in electrical conductivity within the compound bar. EMI informed locations of electrode placement for time‐lapse electrical resistivity imaging (ERI) surveys, which were used to examine changes in electrical resistivity driven by hyporheic exchange. Both geophysical methods revealed a zone of high electrical conductivity in the center of the bar, identified as a fine‐grained cross‐bar channel fill. The zone acts as a baffle to flow, evidenced by stable electrical conditions measured by time‐lapse ERI over the study period. Large changes in electrical resistivity throughout the survey period indicate preferential flowpaths through higher permeability sands and gravels. Grain size analyses confirmed sedimentological interpretations of geophysical data. Loss on ignition and x‐ray fluorescence identified zones with higher organic matter content that are locations for potentially enhanced geochemical activity within the cross‐bar channel fill. Differences in the physical and geochemical characteristics of cross‐bar channel fills play an important role in hyporheic flow dynamics and nutrient processing within riverbed sediments. These findings enhance our understanding of the applications of geophysical methods in mapping riverbed heterogeneity and highlight the importance of accurately representing geomorphologic features and heterogeneity when studying hyporheic exchange processes.

New Understanding of Bar Top Hollows in Dryland Sandy Braided Rivers from Outcrops with Unmanned Aerial Vehicle and Ground Penetrating Radar Surveys

Bar top hollows (BTHs) are morphological elements recognized in modern braided rivers; however, information regarding their depositional features and types of filling units in ancient strata is unclear. This is an important reason behind why it is difficult to identify BTH units in subsurface reservoirs. A Middle Jurassic dryland sandy braided river outcrop in northwestern China is characterized in this study through the application of an unmanned aerial vehicle (UAV) surveying and mapping, and ground penetrating radar (GPR). A workflow of UAV data processing has been established, and a 3D digital outcrop model has been built. By observation and measurement of the outcrop model and GPR profiles, two types of BTH filled units were found: (a) sandstone-filled, and (b) mudstone-filled hollows. Both of these units were located between two adjacent bar units in an area that is limited to a compound bar, and were developed in the upper part of a braided bar depositional sequence. The ellipse-shaped, sandstone-filled unit measures 10 m × 27 m in map view and reaches a maximum thickness of 5 m. The transversal cross-section across the BTHs displays a concave upward basal surface, while the angle of the inclined structures infilling the BTHs decreases up-section. The GPR data show that, in the longitudinal profile, the basal surface is relatively flat, and low-angle, inclined layers can be observed in the lower- and middle part of the sandstone-filled BTHs. In contrast, no obvious depositional structures were observed in the mudstone-filled BTH in outcrop. The new understanding of BTH has a wide application, including the optimization of CO2 storage sites, fresh water aquifers exploration, and oil and gas reservoir characterization.

ИНТЕЛЛЕКТУАЛИЗАЦИЯ ПРОЦЕССОВ КОНТРОЛЯ И УПРАВЛЕНИЯ ЭЛЕКТРОКОНТАКТНЫМ НАГРЕВОМ ПРИ ВОССТАНОВЛЕНИИ ДЕТАЛЕЙ ТИПА ДИСК

We have obtained a modified function of transforming intelligent sensor of contact surface temperature (IS CST) of electric contact “forming the electrode-part” and having a significant influence on quality of restoring the cutting edge of discs of tillage machinery which may only slightly exceed recrystallization temperature of the material of the part. Setting the sensor to restore a specific part is achieved by developing and programming on the microcontroller the function of converting and storing the intelligent system of standard parameters in the non-volatile memory. The re-search goal is to clarify the function of transforming IS CST and to substantiate the opportunity of its application for solution of the set task of control and monitoring. We have provided a schematic diagram of a plant for electrocontact restoration of the cutting capacity of disk tillage tools. The entire restoration process is divided into two stages: static one (without rotating the part) with duration of 1-2 seconds when temperature is monitored in the dynamic mode; and dynamic one, with the set rotation speed of the disc. As a physical analogue of the process, we have considered an “electrode-part” flat contact with a center-located thin com-pound bar thermally insulated at the ends and on the side surface. In addition, a numerical experiment is used to show that introduction to the original polynomial transfor-mation function with three correction indexes enables to reduce the methodological error of measurementsof the contact surface temperature to 0.5°C in the time interval from 1.2 seconds to 1.9 seconds (the electrode material is electro-ceramics).

Estimation of spatial correlation for seismic design of buildings

The paper discusses a solution for the probabilistic problem of high-rise buildings oscillation exposed to seismic loads in form of a six-component random vector. Two groups of matrices for the dynamic response factors to help estimate the effects of spatial correlation between generalized coordinates and correlation in the various seismic vector components on design stresses in load-bearing building structures have been obtained. The spatial model of a building configured as a thin-wall compound bar provides a solution for the probabilistic problem in analytical form.

A minimal continuum representation of a transverse isotropic viscoelastic pulp fibre based on micromechanical measurements

We propose a minimum input mechanical model of pulp fibres. A pulp fibre can be idealised as a complex compound bar, microfibrils render its behaviour anisotropic. The objective of this work is twofold: (i) develop an anisotropic viscoelastic material model of a pulp fibre that shows the essential characteristics with a minimum number of material parameters and (ii) establish suitable experiments with pulp fibres for obtaining these parameters.The model consists of an additive combination of elastic potentials for an isotropic and an anisotropic part. Viscoelasticity is implemented by a generalised Maxwell model. We suggest an incompressible treatment of the material to relate experiments and material parameters in a well-defined manner. By this means, the calibration of the parameters is performed with only two micromechanical experiments, atomic force microscopy nanoindentation on the fibre’s surface and uniaxial tensile tests. We advocate this strategy for certain applications, such as in paper network simulations or fibres in a dry state, when the fibre’s compressibility is of minor importance. The results of this analysis show a good performance of the proposed model applied to pulp fibres.

Hydrosedimentology of the Paraguay River in the Corumbá fluvial reach, Pantanal wetland

The Pantanal wetland is a complex landscape with distinct hydrogeomorphic compartments, with singular and hydrosedimentary processes. Examining these processes draws great interest in understanding Pantanal dynamics for both the management of the system and the geological record predicted by facies models. Hydrosedimentary data in the Pantanal remain scarce, in spite of government efforts to improve and increase data collection in the Upper Paraguay Basin. This study aims to enhance the understanding of active hydrosedimentary processes in the Pantanal Paraguay trunk-river system in the Corumbá reach. Hydrosedimentary surveys were accomplished in the main channel and tributaries of the Paraguay River. These surveys helped characterize the hydrosedimentary dynamics to consider the active sedimentary processes in this reach. The Paraguay River interacts complexly with its floodplain, which functions as a reservoir retaining flood water and disturbing river discharge. Bathymetric surveying showed that Paraguay River channel has longitudinal compound bar bedforms built by superimposition of ripples. The backwater effect, possibly related with both hydrological regime and geomorphological characteristics of the area, was detected by means of rating-curve analysis of the gauge stations. This effect is hydrologically produced by the out-of-phase flood pulse of the Pantanal and geomorphically driven by the hydraulic bottleneck of the Urucum and Bodoquena massifs. Both factors possibly occur simultaneously. The hydrogeomorphic characteristics (morphology, river competence, and stream power) of the Paraguay River denote that the elaboration of models more appropriate to the Pantanal context is needed.

Towards the multi-scale characterization of braided fluvial geobodies from outcrop, core, ground-penetrating radar and well log data

Abstract The integrated application of advanced visualization techniques – validated against outcrop, core and gamma ray log data – was found to be crucial in characterizing the spatial distribution of fluvial facies and their inherent permeability baffles to a centimetre-scale vertical resolution. An outcrop/behind outcrop workflow was used, combining the sedimentological analysis of a perennial deep braided outcrop with ground-penetrating radar profiles, behind outcrop optical and acoustic borehole imaging, and the analyses of dip tadpoles, core and gamma ray logs. Data from both the surface and subsurface allowed the recognition of two main architectural elements – channels and compound bars – and within the latter to distinguish between the bar head and tail and the cross-bar channel. On the basis of a well-constrained sedimentological framework, a detailed characterization of the gamma ray log pattern in the compound bar allowed several differences between the architectural elements to be identified, despite a general cylindrical trend. A high-resolution tadpole analysis showed that a random pattern prevailed in the channel, whereas in the bar head and tail the tadpoles displayed characteristic patterns that allowed differentiation. The ground-penetrating radar profiles aided the 3D reconstruction of each architectural element. Thus the application of this outcrop/behind outcrop workflow provided a solid database for the characterization of reservoir rock properties from outcrop analogues.

Grain‐size variability within a mega‐scale point‐bar system, False River, Louisiana

AbstractPoint bars formed by meandering river systems are an important class of sedimentary deposit and are of significant economic interest as hydrocarbon reservoirs. Standard point‐bar models of how the internal sedimentology varies are based on the structure of small‐scale systems with little information about the largest complexes and how these might differ. Here a very large point bar (>25·0 m thick and 7·5 × 13·0 km across) on the Mississippi River (USA) was examined. The lithology and grain‐size characteristics at different parts of the point bar were determined by using a combination of coring and electrical conductivity logging. The data confirm that there is a general fining up‐section along most parts of the point bar, with a well‐defined transition from massive medium‐grained sands below about 9 to 11 m depth up into interbedded silts and fine–medium sand sediment (inclined heterolithic strata). There is also a poorly defined increase in sorting quality at the transition level. Massive medium sands are especially common in the region of the channel bend apex and regions upstream of that point. Downstream of the meander apex, there is much less evidence for fining up‐section. Finer sediment accumulated more readily after the establishment of a compound bar in the later stages of construction, at the terminal apex and in the bar tail. This work implies that the best reservoir sands are likely to be located in the centre of the point bar, deposited in a simple bar system. Reservoir quality decreases towards the bar edge. The early‐stage channel plug is largely composed of coarsening‐upward cycles of silt to clay and is dominated by clay and clayey silt material with poor reservoir characteristics.

Interaction between the braided bar and adjacent channel during flood: a case study of a sand-bed braided river, Brahmaputra–Jamuna

The braided river is characterized by numerous bars which exhibit chaotic nature and add uncertainty to understand and prediction of the river network. The development of these bars may be affected by several factors like boundary conditions, forcing and non-linear physical processes. Here, in this research, some prevailing physical processes which may affect the growth of bar after its emergence have been examined. Then, attempts have been made to identify the relationships between the bars and their adjacent channels. For this purpose, a two-dimensional-depth-averaged morphodynamic model, Delft3D was used to study the interaction between the braided bar and adjacent channel during a flood in a compound bar dominated area at a large sand-bed braided river-Brahmaputra–Jamuna. The results showed that the 2D model can reproduce the major physical processes which are responsible for the growth of the bar. The study showed that the size and shape of the bars were dependent on the characteristics of the adjacent channels. The occurrence of chute channel over the bartop during the flood depends on the depth of flow over the bar during the flood.

Braided–meandering system evolution in the rock record: Implications for climate control on the Middle–Upper Jurassic in the southern Junggar Basin, north‐west China

This paper presents the current body of knowledge regarding the evolution of a braided–meandering system in the southern Junggar Basin, north‐west China, based on the preserved architecture evidences. The response to climate change was also discussed. Herein, 10 types of lithofacies are summarized, including information of their primary sedimentary structures, characteristic lithology, and geometry. This study focuses on recognizing the architectural elements within the channels (migrating channel: CHm, switching channel: CHs, transiting channel: CHt, and filling channel: CHf), the bar units (downstream accretion: DA, lateral accretion: LA, unit bar: UB, and compound bar: CB), and fine‐grained clastic deposits (floodplain fines: FF and overbank fines: OF). Three representative sections of outcrops were selected, and detailed observation and analysis of these sections revealed 3 stages can be divided: the braided stage, in which the deposits show an evidence of CHm, DA elements which are the mainly architectural elements, multichannel with aggradational filling; The transformation between braided–meandering stage, during which the fluvial system consists of CHt and CHm elements with lateral accretion; and meandering stage which is characterized by dominance of CHm, LA elements, and the channels become isolated and meandering. Finally, this paper concludes with an interpretation of climate events as manifested by the fluvial archives of the colours of sedimentary rocks, special mineral, palaeontology, geochemistry spanning the Middle–Upper Jurassic (between 166.1 and 152.1 Ma).

Sedimentology of a topset-dominated, braided river delta of Huangqihai Lake, North China: implications for formation mechanisms

Sedimentary characteristics and genesis of a sandy, topset-dominated braided river delta from Huangqihai Lake were investigated using trenching and a ground penetrating radar survey. Ten lithofacies types were identified with assistance of grain size distribution to record a broad range of depositional processes within an overall coarsening upward sequence. Four distinct architectural elements, including channel fill, compound bar, sand sheet, and river mouth bar, built up this delta. No obvious foreset can be identified in this braided river delta. A gentle slope (0.2°) and shallow basin (<10 m deep), young age (~25 years), and low sediment supply caused by human disturbance and semi-arid climate, are believed to allow this type of topset-dominated delta to form.

Calculation of Temperature Fields in a Composite Semi-infinite Body Taking Into Account the Generalized Fourier Law

Temperature fields in extended solids and the solids that have symmetry can be described with a high degree of accuracy by one-dimensional heat conduction equation. In this scientific paper the half-space with the layer is simulated using one-dimensional compound bar and consideration is given to the problem of calculation of temperature fields in the compound semi-infinite bar the finite and semi-infinite parts of which have different thermal physical parameters. The heat conduction equation with the fractional derivative in time that takes into account the nonlocality of thermal processes in time is taken as a mathematical model. Lateral surfaces of the compound bar are assumed to be heat isolated and one of the ends of its restricted part maintains the constant temperature. It is assumed that the ideal thermal contact is available at the boundary of bounded and semi-infinite parts of the bar. The solution of initial value-boundary value problem is based on the use of direct and inverse Laplace transformations. The representation of obtained solution in images presents some difficulties. This paper describes the asymptotic analysis of the solution provided that the orders of fractional derivatives in both parts are equal and the variable s of Laplace transformations tends to infinity. In this case the inverse Laplace transformation was obtained using the so-called Mainardi functions. Based on tauberian theorems we can state that the obtained solution can only be used for short times and it is represented as definite integrals of Mainardi functions or generally speaking as generalized power series. In this form it can easily be used for engineering calculations.

Confluence Scours Versus Incised Valleys: Examples From the Cretaceous Ferron Notom Delta, Southeastern Utah, U.S.A

Abstract Confluence scours in braided rivers occur where channel threads join together, producing erosional relief that may be considerably deeper than average channel depth. Based on studies of the continental-scale Ganges–Brahmaputra river system, it has been observed that the maximum depth of confluence scours by autocyclic processes may reach up to four to five times the average depth of the incoming channels. Considering the possibility of such massive scours in an ancient fluvial system, it was argued that allogenically produced incised valleys at sequence boundaries should only be properly defined in ancient systems if the erosional relief is more than five times average channel depth. Based on cross-sectional geometries, a number of confluence scour fills were interpreted on well-exposed fluvial outcrops in a Cretaceous-age compound incised-valley system in the Notom delta complex of the Ferron Sandstone Member, Utah. Cross-sectional observations from outcrops and comparisons with modern rivers reveal that confluence scours have diagnostic fill facies (single set of large steep foresets) and do not produce multistory sand bodies. A confluence scour fill produces a single-story body in which a fifth-order scour is filled with unit bar foresets, which in turn are overlain by a fourth-order surface capped by compound bar deposits. The story thickness in the confluence scour does not represent the average channel depth because confluence scours allow preservation of the deepest parts of channels as well as fully preserved abnormally thick stories. Therefore, we argue that interpretation of incised valleys in the ancient system associated with a sequence boundary should not be based on the depth of the erosional surface versus the number of average preserved channel stories. Rather, it should be defined by the erosional relief that is significantly deeper than the thickest fully preserved stories, which in a braided stream are likely to represent confluence scour fills.

Characterization of a Massive Sandstone Interval: Example from Doko Member of Bida Formation, Northern Bida Basin, Nigeria

A field mapping and laboratory study was undertaken to characterize the lower portion of Bida Formation around Jima and Doko areas near Bida, central Nigeria. Field mapping revealed four lithofacies for the sandy braided river deposits. They are: (1) lithofacies Fa consists of gravely, very coarse sandstones; (2) lithofacies Fb is characterized by gravely, medium to very coarse grained sandstones; (3) lithofacies Fc is identified by coarse silt to fine grained sandstones; (4) lithofacies Fd is recognized by sheet-like beds of fine to medium grained sandstones. They record channel flow (Fa), subaqueous dune (Fb), overbank (Fc) and crevasse splay deposits (Fd) respectively. The four lithofacies allowed the definition of two architectural elements: (1) channel architectural element (CH) and (2) overbank architectural element (OF). A CH element overlain by an OF element defines a unit bar; while stacked, multiple CH overlain by an OF delineate a compound bar. Computation of grain size data for Fa and Fb facies yielded permeability values of 19.4 to 352.3 millidarcies using empirically generated equation. Because permeability values do not vary much, it is suggested that Fa and Fb be treated as one homogeneous entity if object based reservoir modelling of the sandstones is to be done. This work shows that detailed field mapping integrated with grain size data can offer valuable information useful for aquifer and reservoir studies of the sandstones.

Numerical simulation of bar and island morphodynamics in anabranching megarivers

[1] Bar and island morphodynamics in the world's largest anabranching rivers are investigated using a new numerical model of hydrodynamics, sediment transport, bank erosion, and floodplain development, operating over periods of several hundred years. Simulated channel morphology is compared to that of natural rivers and shown to be realistic, both in terms of the statistical characteristics of channel width, depth, and bar shape distributions, and mechanisms of unit bar, compound bar, and island evolution. Results demonstrate that bar and island stability may be sensitive to hydrologic regime, because greater variability in flood magnitude encourages the formation of emergent bars that can be stabilized by vegetation colonization. Simulations illustrate a range of mechanisms of unit bar generation that are linked to local bed or bank instabilities. This link may explain the reduced frequency of unit bars observed in some large anabranching rivers that are characterized by stable vegetated islands and slow rates of channel change. Model results suggest that the degree to which sand-sized bed material is carried in suspension likely represents an important control on bar morphodynamics and channel network evolution, because of its influence on sand transport direction. Consequently, differences in the partitioning of the total sand load between bed load and suspension may provide a partial explanation for contrasting styles of anabranching in the world's largest sand-bed rivers. These results highlight a need for spatially-distributed flow and sediment transport data sets from large rivers, in order to support improved parameterizations of sand transport mechanics in morphodynamic models.

Architecture of the lower terraces and evolution of the Dordogne River at Bergerac (south‐west France) during the last glacial–interglacial cycle

ABSTRACTThe lower terraces of the Dordogne River at Bergerac (south‐west France) were studied in detail using cores, trenches, ground penetrating radar profiles, and 14C, optically stimulated luminescence and infrared stimulated luminescence dating. This study shows that the lowest terrace (Fx) is made up of two major lithostratigraphic units: (i) dominantly horizontal gravel strata interpreted as compound bar deposits in a braided river, which pre‐date 18–17 ka, and (ii) thick lateral accretion gravel units (point bars) formed in an anabranching river during the Late Pleniglacial and Lateglacial. Most of the anabranching channels were abandoned at ca. 11–10 ka following shrinkage of the river bed into a single meandering channel and were partially filled by gyttjas during the Boreal chronozone. Finally, the channels were plugged by overbank fines until about 5 ka. Floods seldom reached the Fx terrace during the late Holocene and accretion became negligible. The main phase of bedrock incision spanned the Holocene, whereas the period of channel adjustment to change in river regime during late Marine Isotope Stage (MIS) 2 only led to a redistribution of the Pleniglacial gravels. The higher terrace (Fw3) formed before the Eemian and was covered by colluvial fans, mainly during MIS 2 and 3. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Optimization design of the send-receive combined compound bar piezoelectric transducer

Send-receive combined compound bar piezoelectric transducer has been widely used in underwater acoustics and ultrasonic fields. The optimization of the send-receive combined compound bar piezoelectric transducer is studied. The effect of the position and the dimensions of the piezoelectric ceramic elements on the resonance frequency, the anti-resonance frequency and transmitting and receiving response are analyzed. The conclusions are beneficial to the optimization of send-receive combined compound bar piezoelectric transducer.