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Motivated by the need to model dose–response or dose‐toxicity curves in clinical trials, we develop a new horseshoe‐based prior for Bayesian isotonic regression modeling a binary outcome against an ordered categorical predictor, where the probability of the outcome is assumed to be monotonically non‐decreasing with the predictor. The set of differences between outcome probabilities in consecutive categories of the predictor is equipped with a multivariate prior having support over simplex. The Dirichlet distribution, which can be derived from a normalized sum of independent gamma‐distributed random variables, is a natural choice of prior, but using mathematical and simulation‐based arguments, we show that the resulting posterior is prone to underflow and other numerical instabilities, even under simple data configurations. We propose an alternative prior based on horseshoe‐type shrinkage that is numerically more stable. We show that this horseshoe‐based prior is not subject to the numerical instability seen in the Dirichlet/gamma‐based prior and that the horseshoe‐based posterior can estimate the underlying true curve more efficiently than the Dirichlet‐based one. We demonstrate the use of this prior in a model predicting the occurrence of radiation‐induced lung toxicity in lung cancer patients as a function of dose delivered to normal lung tissue. Our methodology is implemented in the R package isotonicBayes and therefore suitable for use in the design of dose‐finding studies or other dose–response modeling contexts. [ABSTRACT FROM AUTHOR]

The low level of water and regulation of the Don River runoff led to an irreversible transformation of natural hydrological and hydrochemical processes. At the end of 2022, despite the shortage of river water, the region began laying a water pipeline with a capacity of up to 300 000 m3 of water per day to the Donbass. Are there enough water reserves for the increasing economic needs throughout the year? This work is based on a targeted study of the chemical composition of water under different regimes and sea levels on the Taganrog seashore of the Don Bay and delta. The experiment covers the period from December 2, 2022, until January 30, 2023, and single measurements, for comparison, on February 21, March 30, and April 17, 2023. In total three types of ionic composition typical of the Svinoe delta arm of the Don River are distinguished: first, marine with a dominant (>80%) total amount of sodium and potassium ions, chlorides, and salinity up to 7–9 g/L. Second, the waters of the Don correspond to low salinity (<2 g/L), an increased proportion of Na+ + K+ (50–60%), and a close amount of SO and HCO (30–40% each). Third, since 2018, groundwaters have been regularly recorded when the level decreases. These are medium brackish waters with a salt content >5 g/L. They typically have a high content of sodium and potassium (>60%) and sulfate ions (60–80%). Monitoring shows that the deficit of fresh drinking water will increase, and with increasing withdrawal of water, the deficit will accelerate in time. It will be replaced (up to 5–7 g/L) by mineralized groundwater and water from the Black Sea. The proportions of slightly brackish (2–4 g/L) and medium brackish (4–8 g/L) waters to be pumped (redistributed by seasons) into water pipelines still need to be explored. [ABSTRACT FROM AUTHOR]

In deep karst reservoirs, the internal environment is complex, and thermal stratification isnot the only factor controlling the vertical distribution of the DIC concentration. Previous studies have not fully understood the migration and transformation of DIC in a deep-water reservoir. In this study, a deep-water reservoir in southwest China was chosen, and the spatial and temporal characteristics of the DIC concentration, pCO2, δ13CDIC value, and SIc were investigated. It was found that the Pingzhai Reservoir is a double temperature leapfrog reservoir. The DIC concentration, pCO2, Sic, and δ13CDICvalues showed annual cycle variation. During the thermal stratification phase, the DIC concentration, pCO2, Sic, and δ13CDICvalues were significantly different between the surface layer and the lower layer. However, during the mixing and mixed phases, the differences were not significant. The vertical divergence of the DIC in the Pingzhai Reservoir was influenced by the subtemperate layer, human activities, and sources. The formation of the subtemperate layer was due to the submerged flow formed when river water enteredthe reservoir, which provides a channel for DIC from the river to enter the lower layer of the reservoir. Human activities increased the solubility of carbonate rocks in the reservoir, and the source of DIC was one of the factors contributing to the concentration stratification of DIC in the reservoir. [ABSTRACT FROM AUTHOR]

We consider the computation of the Euclidean (or L2) norm of an n-dimensional vector in floating-point arithmetic. We review the classical solutions used to avoid spurious overflow or underflow and/or to obtain very accurate results. We modify a recently published algorithm (that uses double-word arithmetic) to allow for a very accurate solution, free of spurious overflows and underflows. To that purpose, we use a double-word square-root algorithm of which we provide a tight error analysis. The returned L2 norm will be within very slightly more than 0.5 ulp from the exact result, which means that we will almost always provide correct rounding. [ABSTRACT FROM AUTHOR]

In deep karst reservoirs, the internal environment is complex, and thermal stratification isnot the only factor controlling the vertical distribution of the DIC concentration. Previous studies have not fully understood the migration and transformation of DIC in a deep-water reservoir. In this study, a deep-water reservoir in southwest China was chosen, and the spatial and temporal characteristics of the DIC concentration, pCO2, δ13CDIC value, and SIc were investigated. It was found that the Pingzhai Reservoir is a double temperature leapfrog reservoir. The DIC concentration, pCO2, Sic, and δ13CDICvalues showed annual cycle variation. During the thermal stratification phase, the DIC concentration, pCO2, Sic, and δ13CDICvalues were significantly different between the surface layer and the lower layer. However, during the mixing and mixed phases, the differences were not significant. The vertical divergence of the DIC in the Pingzhai Reservoir was influenced by the subtemperate layer, human activities, and sources. The formation of the subtemperate layer was due to the submerged flow formed when river water enteredthe reservoir, which provides a channel for DIC from the river to enter the lower layer of the reservoir. Human activities increased the solubility of carbonate rocks in the reservoir, and the source of DIC was one of the factors contributing to the concentration stratification of DIC in the reservoir.

Load balancing among virtual machines (VMs) is significant for delivering the cloud services in optimized way with minimum cost paid and total time acquired to deliver the services. In this paper, the various research gaps for load balancing optimization in the past literature have been presented, which need to be addressed for solving the load balancing problem in cloud environment. In present work, Hybrid approach based resource provisioning and load balancing framework for workflows execution has been proposed to optimize the utilization of VMs with uniform load distribution. The proposed framework is based on the hybridization of heuristic techniques with metaheuristic algorithm to achieve its optimal performance in terms of makespan and cost. Two hybrid approaches have been proposed for HDD-PLB framework-Hybrid Predict Earliest Finish Time (PEFT) Heuristic with Ant Colony Optimization (ACO) metaheuristic (HPA) and Hybrid Heterogeneous Earliest Finish Time (HEFT) heuristic with ACO (HHA). The two proposed approaches for load balancing have been analyzed and compared to determine which is superior for proposed HDD-PLB framework. [ABSTRACT FROM AUTHOR]

The performance of integrated hydrocyclone systems in an oil spill removal system is presented. The process was monitored using capacitance sensors and control valves in the underflow and overflow of a hydrocyclone. A series of tests were completed confirming that by adjusting the overflow valve while maintaining other conditions, the oil/water ratio in the underflow can be optimized. This supports the idea that by using the hydrocyclone system, the oil/water ratio in the overflow can be increased by controlling a single valve. To demonstrate the hydrocyclone performance, measurements of the flowrate and oil/water ratio of the overflow were conducted. Experimental results indicated that the water collected in spilled oil can be reduced to less than 5% from the original 25%. Overall performance of the hydrocyclone was shown to be 67.6% ± 2.1% and 35.2% ± 3.5% for inlet oil concentrations of 20 and 40%, respectively. The impact of underflow and overflow flowrates on hydrocyclone performance was presented. [ABSTRACT FROM AUTHOR]

What is the fastest way to solve a linear system Ax = b in arithmetic of a given precision when A is symmetric positive definite and otherwise unstructured? The usual answer is by Cholesky factorization, assuming that A can be factorized. We develop an algorithm that can be faster, given an arithmetic of precision lower than the working precision as well as (optionally) one of higher precision. The arithmetics might, for example, be of precisions half, single, and double; half and double, possibly with quadruple; or single and double, possibly with quadruple. We compute a Cholesky factorization at the lower precision and use the factors as preconditioners in GMRESbased iterative refinement. To avoid breakdown of the factorization we shift the matrix by a small multiple of its diagonal. We explain why this is preferable to the common approach of shifting by a multiple of the identity matrix. We also incorporate scaling in order to avoid overflow and reduce the chance of underflow when working in IEEE half precision arithmetic. We extend the algorithm to solve a linear least squares problem with a well-conditioned coefficient matrix by forming and solving the normal equations. In both algorithms most of the work is done at low precision provided that iterative refinement and the inner iterative solver converge quickly. We explain why replacing GMRES by the conjugate gradient method causes convergence guarantees to be lost, but we show that this change has little effect on convergence in practice. Our numerical experiments confirm the potential of the new algorithms to provide faster solutions in environments that support multiple precisions of arithmetic. [ABSTRACT FROM AUTHOR]

Numerical integration schemes are mandatory to understand complex behaviors of dynamical systems described by ordinary differential equations. Implementation of these numerical methods involve floating-point computations and propagation of round-off errors. This paper presents a new fine-grained analysis of round-off errors in explicit Runge-Kutta integration methods, taking into account exceptional behaviors, such as underflow and overflow. Linear stability properties play a central role in the proposed approach. For a large class of Runge-Kutta methods applied on linear problems, a tight bound of the round-off errors is provided. A simple test is defined and ensures the absence of underflow and a tighter round-off error bound. The absence of overflow is guaranteed as linear stability properties imply that (computed) solutions are non-increasing. [ABSTRACT FROM AUTHOR]

To assure that compression on the rakes of a deep corn thickener does not stop mixing, an additional circular slurry system, which activates slurry all the time, is employed and running resistance is usually decreased. However, there is still uncertainty on how circular parameters affect underflow properties. This means that the design and application of such systems lack support from scientific theories. Hence, it is necessary to create a study on how circular parameters regulate underflow parameters. Analysis of the circular system mechanism shows that its effect can be divided into two parts and the effect of the system on underflow properties is clarified. In addition, the value of underflow concentration in thickeners is solved based on calculus and finally a mathematical model is produced, which simulates the regulation of underflow properties in thickeners. Using the model, the circular parameters of underflow in thickeners are verified. The experiment indicates that the solid concentration of underflow decreases with circular underflow initiation, then tends to stabilize. Also, the volume fraction of underflow increases in the range of 0.7% -2.2% with ascending circular flow and height. In addition, the time necessary for the solid concentration to stabilize is reversely affected by underflow flow and height. The regression function obtained from experimental statistics shows excellent performance in the model when designing and analyzing circular systems for thickeners.

Separation of biomass from culture media by centrifugation and then washing the biomass are mandatory steps in the fermentation process of recombinant Pichia pastoris expressed HBsAg intracellularly. Biomass has to be washed many times to eliminate the culture media residues thoroughly. In this study, we tried to develop the hydrocyclone as an alternative method for separation of biomass from fermentation culture, an attractive replacement for centrifugation processes. The advantages of using hydrocyclone in biomass separation could be summarized in its suitability for continuous separation and its low risk of contamination. To evaluate the performance of hydrocyclone, concentration ratio in underflow to feed stream, capacity, and centrifugal force by considering three parameters of pressure drop, concentration, and the type of hydrocyclone were investigated. Using three level factorial design a concentration ratio equation was developed, with the correlation coefficient R2 = 0.977 ensured the good fitness of the predicted data with the experimental results. In optimal conditions, maximum concentration ratio was 1.246, for flow rate 13.5 LPM and C-force equal to 1276.11 at maximum pressure drop (3 bar) and minimum concentration (0.5% w/w) in hydrocyclone 1. Herein, two different hydrocyclones with the cylindrical diameters of 19 mm and 21 mm were used for separating the yeast cells. [ABSTRACT FROM AUTHOR]

Motivated by the demand in machine learning, modern computer hardware is increasingly supporting reduced precision floating-point arithmetic, which provides advantages in speed, energy, and memory usage over single and double precision. Given the availability of such hardware, mixed precision algorithms that work in single or double precision but carry out part of a computationin half precision are now of great interest for general scientific computing tasks. Because ofthe limited range of half precision arithmetic, in which positive numbers lie between 6 × 10-8 and 7 ×104, a straightforward rounding of single or double precision data into half precision can leadto overflow, underflow, or subnormal numbers being generated, all of which are undesirable. Wedevelop an algorithm for converting a matrix from single or double precision to half precision. It firstapplies two-sided diagonal scaling in order to equilibrate the matrix (that is, to ensure that every rowand column has ∞-norm 1), then multiplies by a scalar to bring the largest element within a factor θ ≤ 1 of the overflow level, and finally rounds to half precision. The second step ensures that fulluse is made of the limited range of half precision arithmetic, and θ must be chosen to allow sufficientheadroom for subsequent computations. We apply the new algorithm to GMRES-based iterative refinement(GMRES-IR), which solves a linear system Ax = b with single or double precision data byLU factorizing A in half precision and carrying out iterative refinement with the correction equationssolved by GMRES preconditioned with the low precision LU factors. Previous implementations ofthis algorithm have used a crude conversion to half precision that our experiments show can causeslow convergence of GMRES-IR for badly scaled matrices or failure to converge at all. The newconversion algorithm computes ≤-norms of rows and columns of the matrix and its cost is negligiblein the context of LU factorization. We show that it leads to faster convergence of GMRES-IR forbadly scaled matrices and thereby allows a much wider class of problems to be solved. [ABSTRACT FROM AUTHOR]

In the Bering Sea around and off the Yukon River delta, surface sediment plumes are markedly formed by glacier-melt and rainfall sediment runoffs of the Yukon River, Alaska, in June– September. The discharge and sediment load time series of the Yukon River were obtained at the lowest gauging station of US Geological Survey in June 2006–September 2010. Meanwhile, by coastal observations on boat, it was found out that the river plume plunges at a boundary between turbid plume water and clean marine water at the Yukon River sediment load of more than ca. 2500 kg/s. Grain size analysis with changing salinity (‰) for the river sediment indicated that the suspended sediment becomes coarse at 2 to 5‰ by flocculation. Hence, the plume’s plunging probably occurred by the flocculation of the Yukon suspended sediment in the brackish zone upstream of the plunging boundary, where the differential settling from the flocculation is considered to have induced the turbid water intrusion into the bottom layer.

Protein secondary structure is closely related to protein tertiary structure and function, and became a hot topic in bioinformatics. The probability graph model HMM (Hidden Markov model) is an important tool in this field. In practice, there exist problems such as: HMM training underflow, significant result differences derived from different training set, and hard process of parameter optimization. In this paper, aiming at HMM training underflow problem when predicting protein secondary structure, we put forward a method for solving the underflow problem; propose an 8-state HMM model to predict protein secondary structure for the first time; and modify parameter to be a three-dimensional parameter containing the state transition information. In order to improve the method drilling the optimal HMM, we train the initial HMM model with each sample, and get a series of new models; then average the parameters of the new models, and the obtained average parameter values are used to construct the optimal HMM model. The improved method increases the accuracy of protein secondary structure prediction, hence it is a good foundation for further improvement of HMM.

Hydrodynamic and acoustic processes associated with a drop impact on a water surface were studied experimentally. Acoustic signals were detected underwater (with a hydrophone) and in air (with a microphone), the flow pattern was recorded with a high-speed camera, and the surface perturbation was monitored with a laser detector. The dimensionless parameters of flows (Reynolds, Froude, and Weber numbers) induced by the impact varied with fall height within the ranges of 5000 < Re < 20000, 20 < Fr < 350, and 70 < We < 1000. The sequence of acoustic signals incorporated an impact pulse at the moment of contact between a drop and the surface and a series of acoustic packets attributable to the resonance emission of gas cavities. The top of the impact pulse, which was detected clearly in the entire fall height range, had a complex structure with short high-frequency and longer low-frequency oscillations. The total number and the parameters of emitted acoustic packets depended to a considerable extent on the fall height. The cases of lacking, one-time, and repeated emission of packets were noted in a series of experiments performed at a constant fall height. The analysis of video data showed that the signal variability was induced by considerable differences in the scenarios of water entry of a drop, which assumed an ovoid shape at the end trajectory segment, in the mentioned experiments. [ABSTRACT FROM AUTHOR]

The results of flotation kinetics the hydrocyclone underflow and overflow in high-grade copper ore processing from the Copper Mine Bor (RB Bor), suggest the possibility of improving the current technological flotation process. This is confirmed by the following results: the distribution of copper in classification product in ration 80:20 % in favor of hydrocyclone underflow as well as higher copper content in the sample and individual class of hydrocyclone underflow compared to the same parameters of hydrocyclone overflow. Participation of optimal size class - 0.075 mm in hydrocyclone underflow is 32.47 %, with copper content of 4.38 %, resulting that about 65 % of total copper in this class to the feed of hydrocyclone is distributed in hydrocyclone underflow and 35 % in the same class in hydrocyclone overflow. Copper recoveries, obtained in laboratory batch flotation tests from hydrocyclone overflow and underflow, are 90.77% and 7.94 %, respectively. Calculated in relation to total copper in the feed of hydrocyclone, 17.30 % Cu can be valorized from hydrocyclone overflow by flotation process, with the same process, 59.58 % Cu is valorized from hydrocyclone underflow, what is 3.44 times more. The results indicate higher copper recovery and slightly better flotation kinetics of hydrocyclone overflow. However, due to better liberation of solid phase and optimization the pulp density in the flotation process, each class of hydrocyclone underflow gives higher contribution to the copper recovery compared to the relevant class of hydrocyclone overflow, calculated on copper, contained in the same class of hydrocyclone feed. Parallel flotation of hydrocyclone overflow and underflow can improve the existing technological process of high-grade copper ore processing in the Copper Mine Bor.

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In this article, we present an efficient algorithm to compute the faithful rounding of the l2-norm of a floating-point vector. This means that the result is accurate to within 1 bit of the underlying floating-point type. This algorithm does not generate overflows or underflows spuriously, but does so when the final result calls for such a numerical exception to be raised. Moreover, the algorithm is well suited for parallel implementation and vectorization. The implementation runs up to 3 times faster than the netlib version on current processors. [ABSTRACT FROM AUTHOR]

An improved one-dimensional (1-D) model for the secondary clarifier, i.e. the Bürger-Diehl model, was recently presented. The decisive difference to traditional layer models is that every detail of the implementation is in accordance with the theory of partial differential equations. The Bürger-Diehl model allows accounting for hindered and compressive settling as well as inlet dispersion. In this contribution, the impact of specific features of the Bürger-Diehl model on settler underflow concentration predictions, plant sludge inventory and mixed liquor suspended solids based control actions are investigated by using the benchmark simulation model no. 1. The numerical results show that the Bürger-Diehl model allows for more realistic predictions of the underflow sludge concentration, which is essential for more accurate wet weather modelling and sludge waste predictions. The choice of secondary settler model clearly has a profound impact on the operation and control of the entire treatment plant and it is recommended to use the Bürger-Diehl model as of now in any wastewater treatment plant modelling effort. [ABSTRACT FROM AUTHOR]

Economical hardware often uses a FiXed-point Number System (FXNS), whose constant absolute precision is acceptable for many signal-processing algorithms. The almost-constant relative precision of the more expensive Floating-Point (FP) number system simplifies design, for example, by eliminating worries about FXNS overflow because the range of FP is much larger than FXNS for the same wordsize; however, primitive FP introduces another problem: underflow. The Signed Logarithmic Number System (SLNS) offers similar range and precision as FP with much better performance (in terms of power, speed and area) for multiplication, division, powers and roots. This paper proposes three variations of a new number system, respectively called the Denormal LNS (DLNS), Denormal Mitchell LNS (DMLNS) and Denormal Offset Mitchell LNS (DOMLNS), which are all hybrids of the properties of FXNS and SLNS. The inspiration for D(OM)LNS comes from the denormal (aka subnormal) numbers found in IEEE-754 (that provide better, gradual underflow) and the μ-law often used for speech encoding; the novel DLNS circuit here allows arithmetic to be performed directly on such encoded data. The proposed approach allows customizing the range in which gradual underflow occurs. Our first DLNS implementation leverages existing SLNS basic blocks. Synthesis shows the novel circuit primarily consists of traditional SLNS addition and subtraction tables, with additional datapaths that allow the novel arithmetic unit to act on conventional SLNS as well as DLNS and mixed data, for a worst-case area overhead of 26 %. Unlike SLNS, this DLNS implementation is still costly for general (non-constant) multiplication, division and roots. To overcome this difficulty, this paper proposes the other variations called Denormal Mitchell LNS (DMLNS) and Denormal Offset Mitchell LNS (DOMLNS), in which the well-known Mitchell's method makes the cost of general multiplication, division and roots closer to that of SLNS. Taylor-series computations suggest subnormal values in DMLNS and DOMLNS also behave similarly to those in the IEEE-754 FP standard. Synthesis shows that DMLNS and DOMLNS respectively have average area overheads of 25 % and 17 % compared to an equivalent SLNS 5-operation unit. [ABSTRACT FROM AUTHOR]

Multimedia streaming applications are traditionally delivered over UDP. Recent measurements show that more and more multimedia streaming data are over TCP as web-based TV, P2P streaming, video sharing websites are getting increasingly popular. To improve the quality of experience (QoE) for users and to cope with variability in TCP throughput, streaming applications typically implement buffers. Yet, for improving the QoE and the streaming quality, e.g., playback continuity and timeliness, it is critical to dimension buffers and the initial buffering delay appropriately. [ABSTRACT FROM PUBLISHER]

Constant bit-rate (CBR) encoding methods used for the real-time digital video applications such as terrestrial high definition television (HDTV) broadcasting often produce large picture quality fluctuation due to constraints on buffer size and buffering delay. In this paper, we propose a simple framelayer CBR encoding method which reduces large picture quality fluctuation of an encoded video under constant bit-rate and limited buffer size. We first define an intermediate encoder buffer level to be lower than the half of the maximum encoder buffer level. Then, the encoder buffer level is kept from being close to the maximum (or minimum) buffer level during encoding by slightly decreasing (or increasing) the number of bits estimated to encode each frame if the resulting buffer level becomes higher (or lower) than the intermediate buffer level. The experimental results show that the proposed CBR encoding method reduces the average local PSNR variation by 20.6% compared with previous CBR encoding method on average under constant bit-rate and limited buffer size. [ABSTRACT FROM PUBLISHER]

The fate of inflows into lakes has been extensively studied during summer stratification but has seen relatively little focus during the weak winter stratification, with or without ice-cover. Field observations are presented of groundwater inflow into a shallow bay of a subarctic lake. Atmospheric forcing of the bay during the study period was extremely variable and coincided with spring ice-cover break-up. Two dominant wind regimes were identified; (1) weak wind-forcing (wind speed <5 m s or land-fast ice-cover), and (2) strong wind-forcing (wind speed >5 m s and open water). At a relatively constant temperature of ~3.3°C, the groundwater inflow was closer to the temperature of maximum density than the water in the main body of the lake, which during the observed winter stratification is ~1.2°C. During weak wind-forcing, the stratification within Silfra Bay approximated two-layers as this denser groundwater formed a negatively buoyant underflow. A calculated underflow entrainment rate of 2.8 × 10 agrees well with other underflow studies. During strong wind-forcing, the water column out to the mouth of the bay became weakly stratified as the underflow was entrained vertically by wind-stirring. Observed periods of mixing can be predicted to occur when turbulent kinetic energy (TKE) production by wind stirring integrated over the underflow hydraulic residence time in the bay exceeds the potential energy associated with the stratification. A decrease of ice cover, as observed in the studied subarctic lake over the last decade, will result in the underflow being more frequently exposed to the strong wind-forcing regime during winter, thereby altering the winter distribution of groundwater inflow within the lake. [ABSTRACT FROM AUTHOR]

One of the open problems in lossless information hiding research is how to get adaptively better difference image architectures for given applications. In this paper we propose a simple and efficient approach to predict high-similar interpolation image from its sparse pattern and spectral expansion. After difference operator, peak value of the spike is very high. This method also provides a mathematic framework for evaluating de-correlating algorithm and can therefore be used to benchmark new algorithms. Finally, a proper reversible data hiding algorithm is also enclosed which refers conventional difference expansion principle. Overflow and underflow is considered in the fusion way. Simulations results demonstrate and verify that our new approach is much effective than local difference expansion method with good generalization performance. [ABSTRACT FROM AUTHOR]

Large tributary inflows into water supply reservoirs caused by heavy catchment rain may be of concern due to problems associated with high levels of natural organic matter (NOM) present in the inflows. The movement of these inflows within a reservoir is dependent on its relative density to the receiving waters. For example, if the inflow is denser (colder) than the recipient water it will travel along the base of the reservoir as an underflow and can penetrate as far as the dam wall water off-take to a water treatment plant (WTP). Field studies were conducted to track the passage of underflows through two South Australian reservoirs, Little Para and Myponga. Samples were collected before and during storm event inflows and analyses undertaken to determine NOM concentration, alum demand, disinfection by-product formation potential, and quality of the water. We demonstrate that by monitoring the movement of inflows into reservoirs, combined with changes in reservoir off-take levels, that the risk of NOM entering a water treatment plant can be reduced which in turn will lower water treatment costs by reducing alum dosing levels and lessen the risk to human health by reducing disinfection by-product formation. [ABSTRACT FROM AUTHOR]

Abstract: A 20mm-diameter electrical hydrocyclone was developed and tested. The presence of the underflow results in a smaller d 50 than the absence of the underflow. Additionally, the higher the feed flow rate, the smaller d 50. Effect of central rod diameter and initial pH of suspension on the separation cut size was examined with and without underflows. The d 50 decreases with the increase of central rod diameter and initial pH values in both with and without the underflow. The zeta potential of particles increases proportionally with the initial pH of suspension. The electrical potential exhibits a stronger effect when the suspension has a higher pH. The d 50 becomes smallest under largest central rod diameter, highest pH and longest slurry collecting box condition operates with the positive electrical potential at side wall in the presence of the underflow. Based on the experimental data, general semi-empirical correlations were proposed and the effect of each parameter on d 50 was examined. [Copyright &y& Elsevier]

Density flow is investigated in a three-dimensional model through a dam reservoir with diverging and sloping bottom channels. When an inflow of higher density enters ambient dam reservoir water, it plunges below the ambient water and becomes density underflow. In the present model, nonlinear and unsteady continuity, momentum, energy, and turbulence model equations are formulated in the Cartesian coordinates. The k-ε turbulence model is used with an extension to include production or destruction of turbulent kinetic energy. To investigate the Coriolis force effect on the density flow in a dam reservoir, a Coriolis force parameter is included in the governing equations. The equations of the model are solved based on the initial and boundary conditions of the dam reservoir flow for a range of bottom slopes and divergence angles. In this paper, variation in density flow parameters, such as velocity, temperature, and turbulence viscosity through the dam reservoir, is investigated. Moreover, mixing rate, plunging points, and plunging depths are determined from the simulation results. The results of the present model are compared with the previous experimental work and model. The present model results follow the expected basic trend. The three-dimensional model simulation and analysis improve the understanding of density flow, underflow, divergence flow, mass transport, and dam-reservoir flow interaction. L’écoulement par densité a été examiné en utilisant un modèle tridimensionnel d’un réservoir de barrage avec, au fond, des canaux divergents. Lorsqu’une eau à haute densité arrive dans l’eau du réservoir de barrage, elle plonge sous l’eau ambiante et s’écoule au fond par densité. Dans le présent modèle, des équations d’un modèle de continuité non linéaire et instable, de momentum, d’énergie et de turbulence sont formulées dans les coordonnées cartésiennes. Le modèle de turbulence k-ε est utilisé avec une extension afin d’inclure la production ou la destruction d’énergie cinétique turbulente. Afin d’examiner l’effet de la force de Coriolis sur l’écoulement par densité dans un réservoir de barrage, le paramètre de la force de Coriolis est inclus dans les équations principales. Les équations du modèle sont résolues en se basant sur les conditions initiales et limites de l’écoulement du réservoir de barrage pour une gamme de pentes et divers angles. Dans cet article, une variation des paramètres de l’écoulement par gravité, tels que la vélocité, la température, la viscosité de la turbulence dans le réservoir, est étudiée. De plus, le taux de brassage, les points où plonge l’écoulement par densité et les profondeurs de plongée sont déterminés à partir des résultats de la simulation. Les résultats obtenus par le présent modèle sont comparés aux travaux expérimentaux et aux modèles antérieurs. Les résultats respectent la tendance de base prévue. La simulation et l’analyse du modèle tridimensionnel améliorent la compréhension de l’écoulement par densité, l’écoulement de fond, l’écoulement divergent, le transport de masse ainsi que l’interaction entre le barrage et l’écoulement dans le réservoir. [ABSTRACT FROM AUTHOR]

A critical component in the delivery of VBR streaming video over packet-based networks, is the playout buffer at the receiver side. As packets will incur a variable delay within the network, a mechanism is needed to dejitter the stream and assure that packets are played out at exactly the same rate at which they were generated by the sender. Packet loss at the playout buffer can be induced by either underflow or overflow, and we first identify the general conditions under which these events occur. These general rules require some knowledge on the network delay characteristics of an arbitrary packet, and are then further developed and refined, by taking a closer look at the case where a single delay bottleneck exists within the network. This analysis allows us to derive useful design rules, where we consider two cases, depending on whether or not the receiver has knowledge about the delay the first packet of the stream has incurred. We conclude by demonstrating that the traditional playout paradigm can be enhanced to guard against large initial delays. [ABSTRACT FROM AUTHOR]

The usual method for evaluating rational Bézier surfaces uses the projection operator and the representation provided by the Bernstein basis. We prove the optimal stability of the basis used in this representation. We also propose an alternative method for evaluating rational surfaces through that representation. We show the stability properties of this last method and prove that it has better properties than other known methods from the point of view of avoiding underflow and overflow. [ABSTRACT FROM AUTHOR]

The impacts of runoff events on external suspended solids loading to Schoharie Reservoir, New York, and patterns of light scattering and sediment deposition in this reservoir are assessed. The assessment is based on monitoring of suspended solids concentrations in the reservoir's primary tributary, detailed vertical profiles of optical backscattering (a surrogate measure of light scattering) in the reservoir water column, and analysis of sediment trap collections, over a seven-month interval of high runoff. These impacts are reported to be tightly temporally coupled and strongly positively related to the magnitude of runoff events. The primary tributary entered the reservoir as a plunging inflow during runoff events, causing conspicuous subsurface peaks in light scattering, with vertical patterns that varied strongly for different events. Deposition quantified by near-bottom trap deployments is reported to be more representative than results from metalimnetic deployments that were generally within, rather than below, the turbid layers. Direct inputs of sediment, transported by density currents, are found to drive deposition, rather than resuspension/redeposition. More than 50 percent of the reported deposition occurred in less than 15 percent of the study period, associated with the four largest runoff events. [ABSTRACT FROM AUTHOR]

Abstract: Finding genes for complex traits is one of the major challenges of modern human genetics. Current developments of molecular techniques facilitated use of large pedigrees and marker sets of thousands of single-nucleotide polymorphisms (SNPs). However, one of the problems occurring in statistical analysis of such large data sets is that the likelihood is very low and underflow may easily occur. In this work we describe a method permitting to avoid underflow during computation of a likelihood function, using different algorithms. Our method makes practically possible analysis of thousands of individuals and thousands of SNPs. The method is easy to implement without major change of the code of existing programs. It also helps to reduce the amount of computer memory used in analysis without noticeable alteration of the program running time. The algorithm was implemented in the software packages for segregation and linkage analysis, which are available from http://mga.bionet.nsc.ru/. [Copyright &y& Elsevier]

Symmetric level-index arithmetic was introduced to overcome the problems of overflow and underflow in the floating-point system. The purpose of this paper is to improve the algorithm performance of SLI arithmetic by introducing an approximation scheme using Taylor's expansion. Following a brief summary of the SLI system and its algorithm for addition/subtraction, the deduction and analysis of Taylor approximation are presented. Also some results from numerical experiments and timing comparisons on possible implementations show the advantage of the approximation method. [ABSTRACT FROM PUBLISHER]

Abstract: A modified structure for floating-point representation, which can essentially eliminate overflow from floating-point calculations, is analyzed. The main part of the paper deals with a computational examination of a model for floating-point exponents and the probabilities of overflow and underflow. Earlier results in the absence of gradual underflow are presented for comparison but the primary focus is on the effect of gradual underflow, a version of gradual overflow, and of a proposal for an extended treatment of these exceptions which we call tapered overflow and underflow. The latter virtually eliminates the exceptions; its overflow threshold is . This paper reviews several models for the distribution of exponents of floating-point numbers and their evolution in the presence of repeated multiplicative operations. A continuous model, which closely approximates the discrete case, is seen to satisfy a functional differential equation with both delay and advance terms. [Copyright &y& Elsevier]

Sediment-laden density underflows are important agents of erosion and deposition and are especially significant in the management of human-made reservoirs, pollutant dispersal, and sediment deposition in the world's oceans. Quantification of continuous, sediment-laden underflows in Lillooet Lake, British Columbia, shows that the underflows descend along a distinct plunge line but, although the input from the source is constant, adopt a distinct pulsing in their velocity structure. Such velocity pulsing will produce temporally and spatially varying bed shear stresses, sediment erosion and/or deposition, and fluid mixing, and represents a central property of underflows that must be incorporated into models of density current behavior. [ABSTRACT FROM AUTHOR]

Spray profile measurements can be used to calculate the underflow rate, and consequently, be related to hydrocyclone performance. The flow geometry of the spray discharge is found to arise from velocity patterns at the outlet orifice. Through a videographic example of an industrial hydrocyclone, it is shown that underflow profiles are typically parabolic, a feature which is indicative of the velocity at which the fluid exits. The inclusion of gravity in this model clearly highlights deficiencies in currently used models. Moreover, an intimate knowledge of factors affecting the profiles of the underflow of a cyclone is essential for the correct interpretation of videographic images. Subsequently, image data are used to estimate outlet velocities, which give an excellent insight into various fluid mechanical phenomena that are not appreciated by analysing basic operational variables. The exit velocities are used to calculate underflow rates, which are related to mass recovery in the underflow. [Copyright &y& Elsevier]

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We study the characteristics of the channel holding time in the multitier cellular systems supporting overflow and underflow schemes with the general call holding time and the general cell residence time. Comparison between our results, together with previous results, and simulation shows that our result is more universal and more accurate. [ABSTRACT FROM PUBLISHER]

The inflow of River Rusizi to Lake Tanganyika has been assumed not to mix with the lake epilimnion as it would sink as an interflow or anunderflow, because of its higher density due to sediment load, lowertemperature and higher salinity. Nevertheless, efforts made to tracethe Rusizi flow into the lake have failed. Ten sampling surveys werecarried out from March 1994 to July 1995. Each consisted of 22 samples, at different distances off the Rusizi estuary and at different depths. Eighteen physical and chemical variables were studied at each site. The Rusizi water was always denser (800 - 1400 g m-3)than the lake water. The relative importance of temperature, suspended solids and salinity varied seasonally. A descent of the Rusizi inflow was observed. Close to the river estuary, river and lake waters mixed and Rusizi sediments settled. Complete mixing occurred within 800 m off- shore. The Rusizi inflow merged with the epilimnion rather than the hypolimnion. Horizontal spread by shorebound currents seemed to be more important than offshore spread. [ABSTRACT FROM AUTHOR]