Probabilistic-Based Design ofWaterjet Propulsors for Surface Effect Ships

Numerical simulations were generated using a nonlinear shallow-water model of velocity potential to study the fundamental processes of tsunami generation and amplification by atmospheric pressure waves. When an atmospheric pressure wave catches up with an existing tsunami that is propagating as a free wave over an abrupt change in water depth, the amplified tsunami propagates in the shallower water. An existing tsunami propagating as a free wave over a sloping seabed is also amplified by being passed by atmospheric pressure waves. When atmospheric pressure waves travel over an abrupt change in water depth, the water surface profile of tsunamis in the shallower water depends on both the interval of the atmospheric pressure waves and the phase of the tsunami-generation process over the change in water depth. Moreover, when atmospheric pressure waves travel over an abrupt change in water depth, the tsunami amplitude in the shallower water increases, as the water depth of the shallower area is decreased and the Proudman resonance is further reduced. When an atmospheric pressure wave train with positive pressure travels over a sloping seabed, the amplification of tsunami crests propagating as free waves is controlled by leaving the forced water waves following the atmospheric pressure waves. Conversely, the amplitudes of tsunami troughs propagating as free waves increase.

Global cooling in marine climates and local tectonic events in Southwest Japan at the Plio–Pleistocene boundary

<p><br><html></p><p><head><br><title>    A research on initial formation process of intermittent debris flow   </title><br></head></p><p><body><br>Some debris flows are intermittent surges flows with discontinuous changes in water depth.<br>These phenomena are considered to be a kind of nonlinear wave phenomena based on flow instability.<br>The authors show a KdV-Burgers equation as an equation representing the change in water depth.<br>When the phase velocity in the equation is long wave velocity, the equation becomes a Burgers equation.<br>The characteristic of the roll wave is that it has a discontinuous change in water depth and flows down intermittently as many surges. </p><p><br><br>Roll wave experiments were performed using a straight channel with a length of 56m, a width of 10cm, a depth of 15cm and a channel gradient of θ=2.5 deg.<br>The experimental conditions are by a plane water and a flow containing 42% (C=0.42) solid particles.<br>The particles are cylindrical particles with a typical particle size of d = 3 mm and a density of σ=1.04 g/cm<sup>3</sup> made of polystyrene. <br>The flow conditions of the plane water are as follows: mean discharge Q = 1112cm<sup>3</sup>/s, <br>mean depth h<sub>0</sub> = 1.23cm at the downstream end of the channel, <br>mean flow velocity u<sub>0</sub> = 90.2cm/s, <br>and the flow conditions with solid particles Q=1193cm<sup>3</sup>/s, h<sub>0</sub> = 1.35cm, u<sub>0</sub> = 88.4cm/s. <br>To supply water to the flume, a water tank storing 0.5m<sup>3</sup> is placed on the upstream side of the flume, <br>and water or a mixture of water and particles is supplied from the upstream end of the flume.<br>The water tank is closed and the inside is kept at a constant pressure according to the Marriott bottle principle. As a result, the water supply is constant.</p><p><br><br>In the case of plane water, the period is T = 1.12sec at x = 14m from the upstream end of the flume, <br>and at the downstream end x = 56m T = 2.25sec. <br>In the flow including solid particles, T = 1.78sec and T = 3.06sec at the same position.<br>In each case, the surge period becomes longer as the flow goes down. <br>The wave velocity of the surge here in the experimental results is different. <br>Looking at the details of the waveform, the subsequent surge may catch up.<br>Therefore, it is considered that the period of the surge becomes longer as it flows down and combines with other surges. <br>In the Burgers equation, the initial condition waveform is integrated into a waveform with wave number k = 1 by the initial condition of a non-integer multiple waveform and non-fixed boundary conditions at both ends.<br>From the above, it is considered that the initial waveform formation of the roll wave is contributed by the weak shock wave equation such as the Burgers equation.<br>In this Burgers equation, when the waveform is integrated into a waveform with wavenumber k = 1, the analytical solution shows that the phase velocity v<sub>p0</sub> is no longer c<sub>0</sub>.<br>Therefore, the governing equation returns to the KdV-Burgers equation.</p><p><br></body></p><p></html></p>

The microfacies of a Lower Cretaceous carbonate drillcore from Oman are characterized using optimizing matrices of Jaccard's similarity coefficients of community. Other than systems tract boundaries, there is no obvious evidence of individual parasequences in the core. However, diagnostic patterns in microfossil distribution identify environmental gradients recording changes in water depth. These gradients are used to define individual parasequences, parasequence sets, stacking patterns and key surfaces. The patterns suggest that deposition was controlled by successive fourth- to fifth-order (high-frequency) relative sea-level cycles superimposed on an underlying third-order relative sea-level rise. Although the correlation of these depositional subunits to systematic changes in water depth and the rate of carbonate accumulation alone is not incontrovertible proof of such a sea-level control, concurrent multiorder relative sea-level cyclicity provides by far the most likely explanation. A microfacies deposited when the water depth was shallowing is characterized by a relay of microfossils with affinities that shallow upwards. Conversely, a microfacies that records a gradual increase in water depth has a relay of microfossils with affinities that deepen upwards. Microfacies characterized by an assemblage of microfossils with similar affinities record deposition when the benthic environmental conditions remained stable, either because of an equilibrium between shallow water carbonate deposition and rising sea level, or in deeper water where sediment composition was relatively insensitive to changes of water depth. Microfacies characterized by mixed affinity assemblages record syndepositional reworking. During periods of embedded multiorder sea-level changes, individual parasequences within systems tracts are shown to record more complex environmental gradients than simply the repetition of successive shallowing-up units as traditionally represented in carbonate sequence stratigraphic models. The microfacies of an individual parasequence may shallow up, or may record both deepening-up and shallowing-up depositional phases, as well as periods of sedimentation when benthic environments remained stable. Individual parasequence boundaries may be submarine or subaerial unconformities, or be conformable, as part of a predictable stratigraphic pattern related to the temporal position of an individual parasequence within the underlying third-order cycle of relative sea-level change. The hitherto ubiquitous use of assemblages to describe carbonate microfacies, coupled with the widespread use of the metre-scale shallowing-up template to identify parasequences, may have led to such complexities previously being overlooked.

Climate and human modifications, including restoration, are changing freshwater availability in wetland ecosystems. Changes in spatiotemporal variability in water depth can influence biogeochemistry and aquatic metabolism (net ecosystem productivity, gross primary productivity [GPP], and ecosystem respiration [ER]). In subtropical wetlands, flocculent organic matter (floc) is a dominant form of organic matter made up of periphyton, macrophytes, and microbes. How changes in water depth with climate and human modifications of subtropical wetlands influence biogeochemistry and the metabolism of floc is uncertain and necessary to understand the consequences for carbon (C) cycling. We collected seasonal floc samples from shorter‐hydroperiod marshes (Taylor Slough Panhandle [TS/Ph]) and longer‐hydroperiod marshes (Shark River Slough [SRS]) in Everglades National Park (Florida, U.S.A.). We measured floc‐specific metabolism and biogeochemistry during the wet (May–November) and dry seasons (December–April) when marsh conditions differed in water depth, photosynthetically active radiation (PAR), floc chlorophyll a, bulk density, and C and nutrients. Floc biogeochemistry was driven by hydrologic changes in water depth, while floc metabolism was influenced by floc biogeochemistry and PAR in both marshes. Floc‐specific metabolism was more net heterotrophic (GPP < ER) in TS/Ph than in SRS, driven by floc bulk density, total nitrogen, total C, total phosphorus, and total inorganic C. Increasing water depths with freshwater restoration may drive higher rates of C loss in shallower compared to deeper marshes. Understanding how hydrologic changes affect organic matter lability and respiration is important in managing C storage in ecosystems.

Cross-sectional-dependent microbial assembly and network stability: Bacteria sensitivity response was higher than eukaryotes and fungi in the Danjiangkou Reservoir.

Recent global change occurs within decades and leaves a significant imprint on shallow carbonate platforms. To what extent can rate and synchronicity of environmental changes in the past be evaluated in order to allow comparisons with the processes and products of today? Sections of a carbonate‐dominated platform of Late Oxfordian age have been logged in detail in the Swiss Jura Mountains. The time frame, based on ammonite biostratigraphy and the hierarchical stacking of the sedimentary sequences, suggests that these formed by low‐amplitude, high‐frequency sea‐level changes in tune with the orbital cycles. The smallest unit, the elementary sequence, can thus be attributed to the 20 kyr precession cycle. By identifying sequence‐stratigraphic elements such as maximum‐flooding surfaces within an elementary sequence, an even higher time resolution can be obtained and reconstructions of changes in water depth and sea‐level are attempted. Sedimentation rates were highly irregular and discontinuity surfaces are common. Correlation of such surfaces from one section to the other is tentative because they could also have formed locally and are not necessarily synchronous. On the scale of elementary sequences, the vertical facies evolution permits interpretation of changes in water depth, which were produced by eustatic sea‐level changes (allocyclic) and/or by autocyclic processes. The distribution of clay minerals indicates changes of sea‐level, as well as of rainfall in the hinterland. Biotic changes were controlled by water depth and water quality, and also by nutrient and clay input. Carbon and oxygen isotopes do not show significant shifts within the elementary sequences. The original ecological, mineralogical and geochemical signals have partly been homogenized because of time‐averaging through bioturbation and through reworking by storms, and because of diagenetic modifications. Consequently, there is potential to interpret environmental changes on the studied carbonate platform but the time resolution is not better than a few thousand years. The rates and the synchronicity of the processes leading to the observed environmental changes can thus be estimated only within this time frame.

Ecosystem functioning is linked to microbial evenness and community composition along depth gradient in a semiarid lake

Wading behaviours, in which an animal walks while partially submerged in water, are present in a variety of taxa including amphibians, reptiles, mammals and birds. Despite the ubiquity of wading behaviours, few data are available to evaluate how animals adjust their locomotion to accommodate changes in water depth. Because drag from water might impose additional locomotor costs, wading animals might be expected to raise their feet above the water up to a certain point until such behaviours lead to awkward steps and are abandoned. To test for such mechanisms, we measured drag on models of the limbs of Chilean flamingos (Phoenicopterus chilensis) and measured their limb and body kinematics as they walked and waded through increasing depths of water in a zoo enclosure. Substantial drag was incurred by models of both open- and closed-toed feet, suggesting that flamingos could avoid some locomotor costs by stepping over water, rather than through it, during wading. Step height was highest while wading through intermediate water depths and while wading at a faster speed. Stride length increased with increasing water depth and velocity, and the limb joints generally flexed more while moving through intermediate water depths. However, movements of the head and neck were not strongly correlated with water depth or velocity. Our results show a wide range of kinematic changes that occur to allow wading birds to walk through different water depths, and have implications for better understanding the locomotor strategies employed by semi-aquatic species.

<p>Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are bacterial lipids that are used as paleotemperature and paleo-pH proxies. Developed originally for application in paleosoils, and geo-archives dominated by soil organic matter, they are also used for temperature reconstructions in lake sediments. For this, brGDGT ratios such as the MBT'<sub>5ME</sub> are translated into mean annual air temperatures using linear transfer functions. However, water depth (Yao et al., 2019; Stefanescu et al., 2021) has recently been shown to influence the MBT'<sub>5ME</sub> values in freshwater lakes. In addition, variable inputs of soil-derived GDGTs can skew the MBT'<sub>5ME</sub> ratio values encountered in lake sediments. Unfortunately, the diagnostic ratios used to recognize either changes in water depth (HP5) or soil input (ΣIII/ΣII), are based on the relative abundance of the same 2 compounds (IIa and IIIa).</p><p>Currently, most of the work on environmental drivers of brGDGT lipids has been done on modern lake sediments. A view on the paleo-variability, i.e. the variability on brGDGTs in lacustrine archives, was still lacking. In this contribution, we will revisit several published and unpublished brGDGT records in last glacial and/or Holocene lake sediments that report a change in soil input and/or water level with time (e.g. Cao et al., 2021; Robles et al., 2022, Ramos-Román et al., submitted). We will use a compilation of these records to highlight how changes in hydrology and soil input influence brGDGT compositions. To distinguish between soil and lake-derived GDGTs, we will employ a novel machine learning approach (linear discriminant analysis). This method allows to identify soil and lake brGDGT distributions in modern soils and sediments (85% accuracy), and is now tested for the first time in paleolacustrine settings.</p><p>We show that natural or anthropogenic changes in the landscape can impact the diagnostic GDGT ratios for soil input and the MBT'<sub>5ME</sub> ratio. The machine learning approach also allows to identify those depths where soil input is significant. This exercise is a first step in investigating the paleo-variability of brGDGTs with a machine learning approach, to determine variables that impact their downcore variability.</p><p> </p><p>Cao J., et al. 2021. Lake-level records support a mid-Holocene maximum precipitation in northern China. Science China Earth Sciences 64, 2161–2171.</p><p>Ramos-Román, M. J., et al. Lipid biomarker (brGDGT)- and pollen-based reconstruction of temperature change during the Middle to Late Holocene transition in the Carpathians. Submitted to Global and Planetary Change.</p><p>Robles, M., et al. 2022. Impact of climate changes on vegetation and human societies during the Holocene in the South Caucasus (Vanevan, Armenia): A multiproxy approach including pollen, NPPs and brGDGTs. Quaternary Science Reviews 277, 107297.</p><p>Stefanescu, I.C., et al. 2021. Temperature and water depth effects on brGDGT distributions in sub-alpine lakes of mid-latitude North America. Organic Geochemistry 152, 104174.</p><p>Yao, Y., et al. 2020. Correlation between the ratio of 5-methyl hexamethylated to pentamethylated branched GDGTs (HP5) and water depth reflects redox variations in stratified lakes. Organic Geochemistry 147.</p>

Sex ratio plays a critical role in population survival. Dioecious plants may simultaneously display sexual dimorphism and deviations from the equilibrium expectation of 1:1 sex ratio in populations, that is, biased sex ratio. However, whether biased sex ratios can be attributed to sexual dimorphism has not been well investigated. Here, we conducted experiments using a three‐water‐depth gradient to examine sexual dimorphism performance and population sex ratios for Vallisneria natans , and investigated the variations in natural population sex ratios for it and two other congeners V. spinulosa and V. denseserrulata along water depth changes. Females of V. natans had higher reproductive investment than males, and the degree of sexual dimorphism increased with increasing water depth. At greater water depths, increased reproductive expenditure led to higher mortality in females, resulting in a male‐biased sex ratio. The sex ratios of natural V. natans and V. spinulosa populations did not significantly deviate from 1:1. In contrast, populations of V. denseserrulata exhibited markedly a female‐biased sex ratio, which may be attributed to female plants producing more clonal ramets. Furthermore, no evidence was found for variation in sex ratios along water depth gradients in natural populations of any of the three species. These findings highlight the plasticity both of sexual dimorphism and sex ratios in dioecious plants, indicating that sex ratios are species‐specific and depend on sex‐specific life‐history strategy shaped by their growth environments.

The quality of most coastal or ocean laboratory experiment depends on the accuracy, uniformity and stability of the generated waves. Generation of waves in the laboratory seems simple, but it should consider the spatio-temporal variability of the wave profile. As they propagate, waves interact with the boundaries, i.e. changes in water depth, lateral walls, test specimens, instrument supporting structures, passive absorbers, etc., as well as with varying hydrodynamic conditions (wave-induced currents, wave-wave interactions, or nonlinear energy transfer, among others). Reflected, scattered and radiated waves may propagate back to the wave generator and reflect back. Re-reflections from the wave generator may be a non-realistic representation of the intended wave field, to the extent that the total energy content in the testing facility may increase significantly and uncontrollably. Theoretically, for weakly nonlinear unidirectional waves propagating over a relatively small number of wavelengths, and as long as the still water depth and facility width does not change, the wave properties should remain constant in space and time, which can be identified as the uniformity and stability of the waves. Under these conditions, nonuniform or unsteady wave properties can be associated to an inadequate selection of the wave theory (Airy, Stokes n-order, Cnoidal, Stream Function, etc., e.g. Fenton 1999), the approximation of the wave generation technique (first or second order, nonlinear - see e.g. Mohtat et al., 2020), formation of wave instabilities (e.g. Benjamin-Feir, 1967), wave reflection, scattering or radiation, and the performance of the active wave absorption system. It can be said that the performance of the active wave absorption control system is one of the responsible factors that can affect directly the quality of the generated waves. Many laboratories have implemented different passive and active wave absorption systems, but the performance on the uniformity and stability of the generated waves, as well as the performance of the active wave absorption system used, have not been assessed in a systematic way, and related published data and information is quite scarce, with few interesting exceptions, e.g. (Lykke-Andersen, 2016; Spinneken 2010; Schäffer and Skourup 1996). However, a direct comparison among the different available active wave absorption control systems is still missing. This paper presents a thorough experimental study on the performance assessment of two different active wave absorption control systems (MTS and Awasys7) as a means to establish the quality of the experiment in terms of the uniformity (space) and stability (time) of generated wave parameters (descriptors) in the laboratory.

Exploring whether diatom diversity in a lake sediment core is representative of that of the entire lake is important for determining the response of lake diatom diversity to global climatic warming. In this study, Yunlong Lake, an alpine lake located in Yunnan Province, Southwest China, was investigated to explore this question over both space and time. Spatially, we investigated diatom diversity patterns in 62 surface sediment samples from different locations and depth zones of Yunlong lake and found essentially constant diatom diversity across the entire lake basin. Temporally, we studied a well-dated sediment core from the lake center to explore whether long-term water-level changes influenced diatom diversity over the last ~ 100 years. Changes in the annual average sediment accumulation rates indicate that the water level of Yunlong Lake increased substantially after the construction of a dam. However, there is no obvious relationship between diatom diversity and water-level changes, which suggests at this site long-term water-level changes did not influence diatom diversity. Comparative analysis of the results for Yunlong Lake with those for other lakes indicates that for relatively strongly mixed lakes with a simple morphology and uniform shoreline microhabitat, such as Yunlong Lake, differences in water depth and changes in water level may not influence diatom diversity. In such cases, the diatom diversity from a sediment core is likely to be representative of that of the entire lake during specific time intervals. Therefore, such lakes may be optimal for studies of changes in past diatom diversity using sediment cores.

Conodont biofacies and watermass structure of the Middle Pennsylvanian North American Midcontinent Sea

The multi-functional one-chip sensor has been fabricated to reduce output variation under various water environment. There were a temperature sensor, a piezoresistive type pressure sensor, and a electrode type conductivity sensor in the fabricated one-chip sensor. This sensor was measured water depth in the range of <TEX>$0{\sim}180cm$</TEX>, temperature in the range of <TEX>$0{\sim}50^{\circ}C$</TEX>, and salinity in the range of 0 <TEX>$0wt%{\sim}5wt%$</TEX>, respectively. Since the change of water depth in solution environment depends on various factors such as salinity, latitude, temperature, and atmospheric pressure, the water depth sensor is needed to be compensated. We tried to compensate the salinity and temperature dependence for the pressure in water by using lookup-table method.