Inflow Part Research Articles

Energy balance analysis for an oscillating water column wave energy converter

The principle objective of this paper is to outline the energy transfer processes occurring in a forward-facing bent-duct oscillating water column (OWC). Phase-averaged data obtained from model scale experiments conducted in monochromatic waves was used in conjunction with linear wave theory to investigate the various energy sources, stores and sinks associated with the three-dimensional OWC geometry. The analysis was restricted to energy transfer from the incoming wave and through the device, the intermediate storage mechanisms and losses, and hydraulic work performed on the power-take-off (which was simulated by an orifice plate). Results based on phase-averaged data presented include kinetic and potential energy for both an undisturbed wave and a wave interacting with the OWC geometry and power dissipated by the orifice. Two-dimensional velocity fields experimentally obtained via particle imaging velocimetry (PIV) were used to examine the kinetic energy and vorticity inside and around the device at its centreline. The main conclusion was that damping caused by the orifice (simulated power-take-off) diverts a proportion of the incoming energy around the device during the water inflow part of the cycle.

Holocene high floods on the Planina Polje, Classical Dinaric Karst, Slovenia

The Planina Polje is located in the northwestern part of Notranjsko Podolje, Slovenia. Annual floods cover the flattened floor of the polje at elevation 445 m a.s.l. and reach the depth of approximately 8 meters. Loamy sediments which were found on surface and subsurface features from the inflow part of Planina Polje up to the elevations of about 495 m a.s.l., indirectly show that floods in the past must have been much more extensive than the recent ones. Radiocarbon dating of flowstone layer from side passage Tiha Jama in Planina Cave revealed that the last such extreme floods appeared around 5,706 ± 49 BP. The time frame of the flood roughly corresponds with the Altithermal (8,000–5,000 BP). More humid mid-Holocene climate might be the main cause for the high floods on Planina Polje.Keywords: geomorphology, floods, radiocarbon dating (14C), Dinaric Karst, Planina Polje, Planina Cave.

The Impact of Pulsing Hydrology and Fluctuating Water Table on Greenhouse Gas Emissions from Constructed Wetlands

Intermittent loading is often used in constructed wetlands (CW) to improve water purification capacity, however, little is known of its impact on greenhouse gas (GHG) emissions.. We studied GHG fluxes in three CWs for municipal wastewater treatment in Estonia: the hybrid CW in Koo had an intermittently loaded (8–10 pulses a day) vertical subsurface flow (VSSF) filter and a horizontal subsurface flow (HSSF) filter with stable water level (10 cm below the surface), the HSSF filter in Kodijarve with higher (42 cm) but more fluctuating water level (from 5 to 75 cm) in inflow and lower (52 cm) but stable water level (30–70 cm) in outflow, and the HSSF filter in Paistu with fluctuating water table (0–70 cm). Intermittent loading enhanced N2O emissions from the VSSF filter in Koo and the inflow parts of the HSSF in Kodijarve. Due to higher organic loading rates in the inflow part of the HSSF in Kodijarve and in the VSSF filter in Koo, the fluctuating water table/intermittent loading did not influence the CO2 and CH4 fluxes. The lower water depths in Paistu resulted in higher CO2 and N2O, and lower CH4 emissions relative to other systems.

Sparse tensor spherical harmonics approximation in radiative transfer

The stationary monochromatic radiative transfer equation is a partial differential transport equation stated on a five-dimensional phase space. To obtain a well-posed problem, boundary conditions have to be prescribed on the inflow part of the domain boundary. We solve the equation with a multi-level Galerkin FEM in physical space and a spectral discretization with harmonics in solid angle and show that the benefits of the concept of sparse tensor products, known from the context of sparse grids, can also be leveraged in combination with a spectral discretization. Our method allows us to include high spectral orders without incurring the “curse of dimension” of a five-dimensional computational domain. Neglecting boundary conditions, we find analytically that for smooth solutions, the convergence rate of the full tensor product method is retained in our method up to a logarithmic factor, while the number of degrees of freedom grows essentially only as fast as for the purely spatial problem. For the case with boundary conditions, we propose a splitting of the physical function space and a conforming tensorization. Numerical experiments in two physical and one angular dimension show evidence for the theoretical convergence rates to hold in the latter case as well.

Differences in rhizome aeration of Phragmites australis in a constructed wetland

Waterlogged soils are a challenging environment for plants due to anoxic conditions and enrichment of phytotoxic substances in the rhizosphere. High contents of organic matter in the substrate as present in constructed wetlands (CW) may amplify these effects. The influence of substrate organic matter on the rhizome aeration of Phragmites australis (common reed) was investigated in a CW for sewage treatment on two sites with different organic concentrations: (a) inflow part of the bed with a high organic charge (high-organic site) and (b) outflow zone of the bed with a lower organic charge (low-organic site). Several diurnal oxygen (O 2) courses were recorded inside the rhizomes using micro-optodes. Maximum O 2 percentages in the rhizomes were generally the same at both sites, but minimum O 2 values were lower in the low-organic site than in the high-organic site, leading to higher amplitudes at the low-organic site. The results suggest that oxygen release from the roots is hampered under high-organic compared to low-organic conditions. This observation might be explained by changes in gas conductivity of the roots, but also by alterations in microbial oxygen demand, under different organic burden.

Redo in aortic homograft replacement: Transcatheter aortic valve as a valid alternative to surgical replacement

CLINICAL SUMMARY A 48-year-old woman was referred to our hospital with symptoms of ingravescent severe dyspnea. Fifteen years earlier, she had undergone placement of a 21-mm aortic valve Bravo 400 stentless xenograft (Cryolife International, Atlanta, Ga). Four years later, she underwent a valve replacement with a 21-mm mechanical prosthesis (Carbomedics, Austin, Tex) for valve degeneration, and subsequently, she received a homograft for aortic valve endocarditis. The echocardiographic control, performed during the last 15 years, showed progressive calcific valve degeneration with a peak transvascular pressure gradient of 41 mm Hg and aortic valve area of 0.5 cm. Preoperative computed tomographic angiographic analysis showed diffuse aortic root

Spatial distribution of bottom sediment deposits in water reservoirs at Zesławice

Spatial distribution of bottom sediment deposits in water reservoirs at Zesławice Spatial distributions of bottom sediment deposits in two small water reservoirs located on the River Dłubnia at Zesławice is presented in this paper. The distribution was elaborated according to Dendy's method on the basis of results of silting measurements performed in the 2005. Horizontal and vertical distribution of sediment deposits was shown as relation between the relative volume of deposited sediments (Sh/S) and relative storage capacity of the reservoir (Vh/V); the vertical distribution of sediment deposits was presented as relation between the relative volume of deposited sediments (Sv/S) and relative reservoir depth (D/Dm). On the basis of performed analysis of horizontal distributions of sediment deposits it was stated that in the main reservoir at Zesławice 58% of the sediment trapped in the reservoir was accumulated in the inflow (upstream part of the reservoir, whose relative volume is 0.25). In the inflow section of the assistant reservoir of relative storage capacity equal 0.22 only 29% of the sediment was deposited. Comparing curves of horizontal sediment deposits distribution in the main reservoir in its inflow part according to measurement data from the 2005 and 1986 i.e. from a comparable period of operation before desilting and building of an assistant reservoir it was stated that relative volumes of sediment trapped after desilting are over 40% higher than before desilting. In a comparable period of operation before desilting (measurement in the 1983) and after desilting (measurements in the 2005) i.e. after seventeen and sixteen years respectively in the main reservoir the accumulated sediments formed an isle - the value Sv/S equaling 0.09 for D/Dm equal 0 in consequence of a change of hydraulic conditions of water and sediment flow - due to a part of inflowing water of the River Dłubnia being directed to the assistant reservoir.

Computer‐Aided Optimization of the Extrusion Process of Automobile Rubber Seal

In this work, the extrusion process of a kind of π‐shape automobile rubber seal was considered using computer‐aided simulation technology. The extrusion flow was assumed to be isothermal and steady, and the finite element method was used to analyze the extrusion process. It was found that the velocity profile was quite uneven near the die exit when a straight die, developed strictly according to the desirable product dimension, was used and the local distortion of the extrudate was fairly prominent when compared with the die geometry. We adjusted the structure of the die and predicted the extrudate's swell by the computer simulation in advance. Simulation results confirmed that the distortion of the seal was greatly suppressed if a short enlarged inflow part was added to the upstream of the original straight die. Then, the extrusion experiment, using the newly designed die, was performed under practical conditions and the swell of the rubber seal was reduced to be within the range of acceptable tolerance. The profiles of the acceptable rubber seals were also well predicted by the computer simulation. Finally, the influences of the take‐up imposed on the end of extrudate and flow rate on the final seal shape were also investigated numerically.

STUDY ON EVALUATION OF ARTIFICIAL IMPLANTABLE LUNG DESIGN

In a previous study, we constructed an automatic optimization system applying Multi Objective Genetic Algorithm (MOGA) and Computational Fluid Dynamics (CFD), and developed an Artificial Implantable Lung (AIL) possessing antithrombogenicity and high gas exchange performance based on fluid dynamics. In the result of in vitro experiment, this system was shown to be useful as a design and development support system for high-performance artificial organs. In the currently study, we evaluated the AIL design for further long-term use using the designs optimized by the automatic optimization system. The velocity and pressure distribution was calculated by CFD software STAR-CD (CD-adapco, JAPAN). Two AIL designs (original design: OD and optimum design: OPT) were used in order to evaluate AIL design. OD was characterized by arc extrusion shape and symmetry at the inflow and outflow parts. OPT had taper shape and asymmetry at the inflow and outflow parts. In OPT, the uniformity of flow velocity to the fiber bundle was decreased by 75.1% and the gas exchange performance was increased by 29.4% when compared with OD in the previous optimization. In OPT, the flow velocity attenuated with the taper wall in the inflow part. High pressure was caused in the taper wall and the pressure was decreased by almost constant value. In conclusion, it was considered that the fluid kinetic energy was converted into the pressure energy by the taper wall in the inflow part, and the fluid was uniformly diffused to the fiber bundle by the pressure.

Monitoring in Senjyogahara wetland using multitemporal LANDSAT TM/ETM+data

The purpose of this study is a monitor of Senjyogahara wetland by multitemporal LANDSAT TM/ ETM+ data. Four indices of NDVI, MWCI, Cv, and Cw were used for the analysis. Cv, and Cw are indices calculated by the pattern decomposition method. The principal component analysis (PCA) and the change vector analysis (CVA) were used for the time series analysis. As a result of the PCA, the principal ingredient in which the change in the period was shown about four indices was able to be obtained. The change of 15 years in the marshland was clarified by the result of those principal ingredient and CVA.1) Senjyogahara region is made dry.2) Odashirogahara region is made moist.3) Sakasagawa-river inflow part is made dry.4) The water current dividing into parts with the national road has gone. The above-mentioned tendency was able to be confirmed.

Extracellular phosphatase activity of freshwater phytoplankton exposed to different in situ phosphorus concentrations

Extracellular phosphatase production and biomass change were investigated in phytoplankton species transplanted from the phosphorus-limited dam area of a eutrophic reservoir and exposed to the phosphorus-sufficient inflow part and vice versa. Extracellular phosphatase activity was studied using the enzyme-labelled fluorescence (ELF) technique, allowing for direct microscopic detection of enzyme activity and, moreover, its quantification using image cytometry. Several phytoplankton species (e.g. Anabaena planctonica, Microcystis aeruginosa, Fragilaria crotonensis, Ankyra ancora and Planktosphaeria gelatinosa) regulated phosphatase activity according to external phosphorus concentration. On the contrary, picocyanobacteria and several green algae (Coelastrum microporum, Crucigeniella sp., Pediastrum tetras, and Staurastrum planctonicum) did not produce extracellular phosphatases at all. The species-specific extracellular phosphatase activity of F. crotonensis, A. ancora, and P. gelatinosa ranged between 0.02 and 3.5 fmol μm−2 h−1.

Effects of decreased resource availability, protozoan grazing and viral impact on a structure of bacterioplankton assemblage in a canyon-shaped reservoir

We conducted a transplant experiment to elucidate the effects of different levels of grazing pressure, nutrient availability, especially phosphorus, and the impact of viruses on the changes in the structure of bacterioplankton assemblage in a meso-eutrophic reservoir. A sample taken from the nutrient-rich inflow part of the reservoir was size-fractionated and incubated in dialysis bags in both inflow and dam area. The structure of bacterial assemblage was examined by fluorescence in situ hybridization using oligonucleotide probes with different levels of specificity. In terms of the relative proportions of different bacterial groups, we found very few significant changes in the bacterioplankton composition after transplanting the treatments to the nutrient-poor dam area. However, we observed marked shifts in morphology and biomass towards the development of filaments, flocs and “vibrio-like” morphotypes of selected probe-defined groups of bacteria induced by increased grazing pressure. Despite the very high abundances of viruses in all the treatments, their effects on bacterioplankton were rather negligible.

Driving forces and boundary conditions in continuum dislocation mechanics

As a guide to constitutive specification, driving forces for dislocation velocity and nucleation rates are derived for a field theory of dislocation mechanics and crystal plasticity proposed in Acharya (2001, J. Mech. Phys. Solids 49, 761–785). A condition of closure for the theory in the form of a boundary condition for dislocation density evolution is also derived. The closure condition is generated from a uniqueness analysis in the linear setting for partial differential equations controlling the evolution of dislocation density. The boundary condition has a simple physical meaning as an inward flux over the dislocation inflow part of the boundary. Kinematical features of dislocation evolution, such as the initiation of bowing of a pinned screw segment and the initiation of cross–slip of a single screw segment, are discussed. An exact solution representing the expansion of a polygonal dislocation loop is derived for a quasilinear system of governing partial differential equations. The representation within the theory of features such as local (dislocation level) Schmid and non–Schmid behaviour as well as (unloaded) stress–free and steady microstructures are also discussed.

A Numerical Study on Premixed Flame Propagation in a Swirling Flow.

In order to clarify the rapid flame propagation mechanism along a vortex axis (the vortex bursting phenomenon), the steady state propagation characteristics of premixed flame in a vortex tube have been examined in detail by the numerical calculation. In this calculation, the flame is fixed in the computational domain by adding an axial flow to the unburnt premixed gas. The obtained results show quantitatively for various flow conditions that, with increasing the maximum tangential velocity, the flame propagation speed increases proportionally, and the flame diameter decreases and approaches to a constant value, and the results are independent of the kind of the vortex. Moreover, the results show that the variation of the pressure along the vortex axis occurs between the inflow part and the flame front and the pressure in the burnt region is almost uniform, and that the propagation speed corresponds to this pressure difference and it is estimated by the Bernoulli's equation.

Cellular sodium transport in arterial wall - summary of studies by digital computer simulation

The distribution of electrolytes between extracellular and intracellular compartments is of greater functional significance in biological tissues than the total amount. A method commonly employed for the study of a substance distribution among different spaces is the continuous outflow and radioisotope counting of a fragment of tissue previously incubated with a radioactive tracet (here 22Na +). The experimental data can be analyzed within the frame of a compartmental analysis system which is defined by transport rate constants (k ij) and solved when all k ij are numerically determined. In practical applications the direct solution requires measurements in different compartments or knowledge of the initial condition for each compartment, but this is not possible in most biological tissues where the experimentally observable data represent the summation of tracer in all compartments at each point in time. The availability of the SAAM (Simulation, Analysis And Modelling) computer program allows for a powerful simulation procedure to arrive at values for k ij . Experimental data and specifications for a chosen model are entered in the SAAM format. A simulated ‘inflow’ experiment is mde by the computer by assigning to k ij some estimate values. All initial conditions are now zero, since at the beginning there is no radioactive tracer in any compartment. After a time equivalent in the experimental realm to achieving constant specific activity, a ‘time change’ programmed into the computer takes place so that the outflow part of the experiment is developed with the same k ij as for the inflow part, the final conditions for the inflow before the time change being the initial conditions for the outflow. An iterative procedure modifies the initial estimates of k ij to seek the best fit. By coupling a powerful simulation procedure to an advanced radionuclide tracer biological methodology, we have been able to find effects of the hormone aldosterone and of experimental hypertension on Na + distribution in arterial wall years before such effects were demonstrated by purely conventional experimental techniques. This computer simulation procedure may be suited to other experimental situations in which outflow data are the only available.

The Unconditional Instability of Inflow-Dependent Boundary Conditions in Difference Approximations to Hyperbolic Systems

The stability of finite difference approximations to initial boundary hyperbolic systems is studied. As is well known, a proper specification of boundary conditions for such systems is essential for their solutions to be well defined. A discrete analogue of the above is proved - if the numerical boundary conditions are consistent with an inflow part of the problem, they render the overall computation unstable. An example of the inviscid gasdynamics equations is considered.

Mechanism of systolic anterior motion of mitral valve and site of intraventricular pressure gradient in hypertrophic obstructive cardiomyopathy.

The mechanism of systolic anterior motion of the mitral valve and the localisation of the intraventricular pressure gradient were determined in 15 cases of hypertrophic obstructive cardiomyopathy by the combined use of real time two dimensional echocardiography and intracardiac manometry. We arrived at the following conclusions. The systolic anterior motion of the mitral echo in the M-mode echocardiogram can be classified into two types, I and II, based on two dimensional echocardiographic findings. In type I, the echo sources of systolic anterior motion are the anteriorly shifted mitral chordae and, in part, the papillary muscles. The intraventricular pressure gradient occurs at the level of the tip of the papillary muscle. The suprapapillary part of the outflow tract and the inflow part show a low pressure, while the apical cavity shows a high pressure. In type II, the echo sources of systolic anterior motion are the anterior and posterior mitral leaflets which are oriented in such a way as to obstruct the outflow tract. The pressure gradient occurs at the level of the anterior and posterior mitral leaflets. The inflow tract and the outflow tract just below the mitral leaflets show a high pressure, in contrast to type I systolic anterior motion. The inappropriate and maloriented papillary muscles play an essential role in causing both types of systolic anterior motion and outflow obstruction. The direction of the axis of the papillary muscle is changed in late systole, moving its tip away from the interventricular septum, resulting in a simultaneous reduction in systolic anterior motion.

The unconditional instability of inflow-dependent boundary conditions in difference approximations to hyperbolic systems

It is well known that for a mixed initial-boundary hyberbolic system to be well-defined it is necessary to impose additional boundary conditions only on the inflow eigenspace of the problem. We prove the discrete analogue of the above concerning difference approximations to such a system; that is, imposing numerical boundary conditions which are at least zeroth-order accurate with an inflow part of the interior equations leads to unconditional instability.

The “Goose Neck” of the Endocardial Cushion Defect: Anatomic Basis

The “goose neck” deformity as seen In left ventriculograms in the endocardial cushion defect persists after surgical treatment in which the subaortic deficiency of the ventricular septum is built up with prosthetic material and the natural mitral valve is replaced by a prosthesis. Anatomic studies indicate that the diaphragmatic (inflow) aspect of the left ventricle and the ventricular septum are short relative to the outflow length of the ventricular septum. In addition, there is a deficiency in the subaortic aspect of the ventricular septum. The study suggests that the term “goose neck” deformity following correction of the deficiency of the ventricular septum appears to be related to the short nature of the inflow part of the left ventricular wall at its diaphragmatic aspect. The study suggests that the term “goose neck” deformity is better replaced by “goose” deformity, since the deficient posterior wall of the left ventricle outlines the curvature of the back of the “goose” which persists in spite of correction at operation.