Basin Stability Research Articles

Analysis and control of bifurcation phenomena in aircraft flight

This paper addresses a theoretical framework for a unified methodology which allows analysis of nonlinear stability and efficient control of high-dimensio nal nonlinear plants modeling aircraft flight. It is shown that analysis of nonlinear transition phenomena (bifurcations) is central to revealing the limitation of robust control (i.e., an accurate estimate of the basin of stability). Omitting transition behavior causes over control and provides a very local stabilization. Analysis and control of bifurcations of aircraft flight are given in the spirit of the generalized normal forms method, which provides one with the nonreducible system that preserves stability characteristics of the initial plant. Stabilization of a plant's bifurcations is then given in terms of the resonance control methodology. Efficiency of the developed methodology is demonstrated by analyzing and controlling an unstable nonlinear plant relevant to the lateral dynamics of an aircraft. Whereas the initial plant is governed by a number of coupled nonlinear equations, the reduced system (the resonance normal form) turns out to be much easier to analyze and even integrable in many cases. Analysis of bifurcations of the resonance normal forms may shape efficient control actions which a pilot may undertake to ensure stability of an aircraft in a prescribed neighborhood of a trim condition and also can furnish a design of a flight's automatic control.

Chlorinated Phenolics Removal from Bleached Kraft Mill Wastewater in Three Secondary Treatment Processes

Laboratory-scale activated sludge (AS), facultative stabilization basin (FSB) and aerated stabilization basin (ASB) processes were operated in parallel treating bleached kraft mill effluent under controlled SRT and temperature conditions, to assess the chlorinated phenolics removal efficiencies attainable in each. The structure and extent of chlorination of the chlorophenolic compounds monitored appeared to contribute to the differing removal efficiencies observed. Under most operating conditions, treatment process effluents contained chronically toxic levels of pentachlorophenol-equivalent toxicity (TEQ). A companson of the results obtained from the FSB, ASB and AS processes indicated that, under most operating conditions, chlorophenolics removal in low rate treatment systems is superior to that in a higher rate activated sludge treatment process. However, it was also observed that operation at long SRT and moderate temperature permitted enhanced removal of chlorophenolics and reduced TEQs to less than threshold values, in all three treatment processes.

Removal of toxicity and some nonconventional pollutants by a dual power multicellular lagoon system

ABSTRACT: Aerated stabilization basins (ASBs) are a common unit process for treating pulp and paper mill wastewaters in North America but are often unable to meet current requirements. One possible solution is the conversion of the existing system to a dual power level multicellular aerated lagoon. The dual power level lagoon process is a higher rate modified ASB system allowing effluent improvement, energy optimization, and total detention time reduction. To evaluate the suitability of such a system for the treatment of unbleached kraft mill effluent mixed with a municipal wastewater, industrial scale pilot plant tests were conducted over a period of 9 months. The BOD removal kinetics and the ability of the system to reduce effluent toxicity were evaluated for several operating conditions. The dual power level multicellular lagoon process was able to produce effluent nontoxic to rainbow trout, Daphnia magna, and photoluminescent bacteria, despite a median lethal concentration of the untreated effluent in the range of 18 to 24% (96 h LC 50). This effluent also met the requirements for BOD and suspended solids. The treated effluent was analyzed for several nonconventional pollutants (including toluene, styrene, phenolic compounds, and surfactants) and some extractable organic compounds. In general, few contaminants showed concentrations above analytical detection limit levels. Those that did have positive values were generally present in concentrations less than 1 μg/L. The observed concentrations were consistent with a joint U.S. EPA and Ontario Forest Industry Association screening study of pulp and paper mill effluents. The concentrations were close to analytical detection limits.

Erosion of the basin of stability of a floating body as caused by dam breaking

The dam breaking problem in terms of changing water levels behind and ahead of the dam, has been solved in the shallow water model. Here the effect of dam breaking on a symmetric downstream floating body is considered. A forced Duffing equation model, proposed by one of the authors, is used. The analysis has practical implications in terms of how far a marina should be situated from a large dam. Comparison with basin erosion, as caused by a water surface soliton, is instructive.

The 1/ d expansion for the quantum mechanical n-body problem application for directed polymers in a random medium

In this paper we give a closed form expression for the 1/ d corrections to the leading d → ∞ approximation for the ground-state energy of an n-body quantum mechanical problem in a general potential (where d is the number of spatial dimensions). We then extend the results to the problem of directed polymers in a random medium where the limit n → 0 has to be taken in the corresponding n-body problem. In this case the effective two-body potential measures the strength of correlations of the quenched disorder. In the n → 0 limit a replica-symmetry-breaking solution to the saddle-point equations turns out to be the correct solutionin the strong-coupling regime, and we obtain the 1/ d corrections to the corresponding energy which constitute the gaussian fluctuations about this solution as well as provide information about its basin of stability.

Comprehensive Study of a Bleached Kraft Mill Aerobic Secondary Treatment System

Abstract A comprehensive study (physical, chemical and biological parameters) was made of a conventional secondary treatment system (aeration stabilization basin) linked to a state-of-the-art bleached kraft mill. Overall the system removed 88% of the BOD, 62% of the COD, 47% of the TOC, 56% of the AOX and 69% of the suspended solids present in the influent stream. Of the total removed, the first aeration cell was the most active area of the system, responsible for the removal of 70% of the BOD5, 57% of the COD, 43% of the TOC, 75% of the AOX, and all of the acute toxicity entering the system. Cell 2 was found to be carbon limited. Unlike Cell 1, Cell 2 played a significant role in suspended solids removal.

Changes in Maturity, Plasma Sex Steroid Levels, Hepatic Mixed-Function Oxygenase Activity, and the Presence of External Lesions in Lake Whitefish (Coregonus clupeaformis) Exposed to Bleached Kraft Mill Effluent

Lake whitefish (Coregonus clupeaformis) exposed to primary treated bleached kraft mill effluent (BKME) had reduced gonadal development and increased liver size relative to two reference populations. These results parallel our previous work on the white sucker (Catostomus commersoni) exposed to BKME at the same Lake Superior site. More detailed studies conducted in 1990, after the installation of an aeration stabilization basin at the pulp mill, found that lake whitefish exhibited reduced gonad sizes, delayed age to maturation, decreased levels of the plasma sex steroids testosterone and 17β-estradiol, and elevated hepatic mixed-function oxygenase (MFO) activity. Liver size was smaller following operation of the secondary treatment system. More than 20% of the lake whitefish collected at the BKME site in 1990 exhibited lateral, slash-like lesions which penetrated the body cavity. Histological examination revealed no evidence of an infectious etiology, and the wounds could not be accounted for by known causes. Similar lesions were found in 1991 near a second BKME discharge.

AOX Removal from Bleached Kraft Mill Wastewater: A Comparison of Three Biological Treatment Processes

Laboratory scale activated sludge (AS), facultative stabilization basin (FSB) and aerated stabilization basin (ASB) processes were operated under controlled parallel conditions to assess the AOX (adsorbable organic halogen) removal efficiencies attainable in each. A comparison of the results obtained under a variety of operating conditions indicated that higher removal efficiencies of total and filterable AOX were achieved in the FSB and ASB processes than in the AS system. Data are also presented to indicate the extent to which influent AOX was removed by biodegradation, biosorption and off-gas stripping.

The Removal of Chlorinated Organics from Conventional Pulp and Paper Wastewater Treatment Systems

A two-year survey of adsorbable organic halide (AOX) removals was conducted for eight full-scale wastewater treatment systems operated at pulp mills in North America. The resulting AOX database, one of the most comprehensive currently available, supports several significant findings. AOX removals averaged 46% for the two activated sludge systems and 34% for the five aerated stabilization basins (ASBs). Both the activated sludge facilities and ASBs averaged removing over half of the influent low molecular weight AOX. The average removal of high molecular weight AOX varied among mill sites from 1% to 47% and was not correlated with the type of treatment process used. The best-performing treatment facility, located at a sulfite mill receiving nearly 100% hardwood furnish and using an activated sludge treatment system, was able to consistently remove 53% of the AOX, 62% of the low molecular weight AOX, and 47% of the high molecular weight AOX in bleaching wastewaters. Factors responsible for this high performance are not currently understood. Effluent AOX was strongly correlated (R2 = 0.90) to the influent loading for ASBs. In-mill improvements such as the use of oxygen and peroxide as well as chlorine dioxide substitution reduce influent AOX loading, apparently with minimal impact on treatment plant removal efficiency.

Control of effluent from the manufacturing of bleached pulp and paper from bagasse

Waste water and its treatment have been studied for pulp and paper manufacturing from sugar cane bagasse and compared to wood pulping and straw pulping. The study included the ability of an activated sludge/aerated lagoon plant to remove chlorophenolics from the effluent. on the basis of a chemical wastewater. This paper is a compilation of the results. The Panchito Gómez Toro Plant is a greenfield integrated pulp and paper mill from 1984 using a modified kraft process based on wet depithed bagasse. The daily pulping capacity is 200 tonnes of air dry pulp (t 90). The bleach plant has four stages (C/D E H D). The wastewater treatment is based on aerated, activated sludge and subsequent treatment in a stabilization lagoon with 11 days' retention time. The operation of the activated sludge plant is troublesome due to shock loads of TSS (total suspended solids) and COD (chemical oxygen demand) from the mill, and an inadequate supply of chemicals for coagulation in primary treatment. Consequently, the influent to and the effluent from the activated sludge plant are often high in TSS and COD. The effluent from the lagoon is colored and high in TSS. The quantities of chlorophenolics formed during the bleaching of brown pulp are unexpectedly high. By analogy to a previous study of straw pulp bleaching this is presumably due to high temperatures in the chlorination tower and inappropriate control of chlorine dosing. Generally, chlorophenolics are removed biologically, especially during lagoon treatment. Still, some highly chlorinated and highly substituted phenolics resist the biological wastewater treatment. Conclusions are that aerated stabilization basins are more energy-effective for effluent treatment in tropical zones than activated sludge treatment, and in developing countries they may perform better owing to a better resistance towards shock loads of TSS from improper fiber control in the mill.

Multistability and associative memory in a phase-conjugating resonator

I derive and analyze coupled-mode equations for a double phase-conjugating resonator that is loaded with a volume-holographic recording medium in which multiplexed images have been stored. If the only nonlinearity present is the saturating gain of the conjugators, there is no multistability: The most deeply imprinted image always wins the competition for saturation. If several images are imprinted with equal depth, any slowly varying superposition of these images is neutrally stable. However, if a nonlinearity, arising from a space-charge-dependent cubic polarization, is present the resonator does exhibit multiple basins of stability that correspond to the faithful reconstruction of each stored image. The momentary injection of an initial image will tip the system into the basin that corresponds to the stored image that it most closely resembles, even if that image is not the most deeply imprinted one.

Tertiary Fluvial Systems Within the Bear Creek Coal Field, Northern Big Horn Basin, Montana

The Bear Creek coal field contains the 250-m-thick coal-bearing Paludal Member of the Paleocene Fort Union Formation in the northern Big Horn Basin, Montana. Detailed field and subsurface data show two contrasting geometries in alluvial strata, each bounded by an economic coal bed. The lower 50 m of the Paludal Member is dominated by sheet and ribbon sandstones. The sheet sandstones are as long as 1.5 km and fine upwards from medium to fine grained. Some sandstones are multistory with sharp upoper and lower contacts. The upper portion has convolute bedding, ripple lamination, and some horizontal and tabular crossbeds. Stratigraphically higher is a 12-m-thick fine-grained sequence, containing large tree trunks in growth position and extensively rooted mud rocks. Sandstone bodies, 6 m thick and 10 m wide, are enclosed within mudstones and siltstones. The sandstones are primarily ripple laminated and have stepped bases and internal erosion surfaces. This interval has previously been interpreted as deposits of an anastomosed fluvial system. The sandstones show little evidence of significant lateral migration. In contrast to the lower interval, the environment here consisted of well-developed vegetated islands separating fluvial channels. Subsurface data show that the major coal beds are laterally continuous within the studymore » area. The cyclic development of the coals reflects intermittent periods of long-term basin stability. Alternating dominance of the sandstones suggests that influx and distribution were controlled through episodic uplift of the nearby Beartooth Mountains.« less

Multistability, chains, and cycles in optical multiwave mixing processes

We exhibit the information processing capabilities of the first few terms that arise in the amplitude expansion for resonant scattering in a medium with a delay nonlinearity (generalized volume hologram). We begin by showing how the physics of intensity dependent charge transport near a two-photon resonance gives both delayed quadratic and quartic nonlinearities. After reviewing the utility for matrix associative memories exhibited by the delayed quadratic nonlinearity (the ordinary Gabor hologram), we examine the role of the quartic nonlinearity, which is a fourth rank tensor. The symmetries of this tensor determine the information processing capabilities (via multilinear correlations) of the medium in an optical computing paradigm. We find multiple basins of stability, Jordan strings, and cycles as possible dynamic behaviors for the medium. We indicate how each corresponds to an information processing task: multiple basins to multiassociative memory, Jordan strings and cycles to chain and sequence memory and to group-invariant pattern recognition. We briefly indicate how branching processes may be implemented by the fourth rank mode-coupling tensor.

Problems in determining the return of a watershed to pretreatment conditions: Techniques applied to a study at Caspar Creek, California

Using a previously treated basin as a control in subsequent paired watershed studies requires the control to be stable. Basin stability can be assessed in many ways, some of which are investigated for the South Fork of Caspar Creek in northern California. This basin is recovering from logging and road building in the early 1970s. Three storm‐based discharge characteristics (peak discharge, quick flow, and total storm flow), daily flows, and concentration of suspended sediment were studied to see if the South Fork can be used as a control in a second experiment. Mean sediment concentration in three discharge classes and regression parameters for the other data were tested to estimate remaining treatment effects relative to the North Fork. Patterns of change were similar for most data, with rises in response followed by returns toward pretreatment conditions. The storm and sediment data showed few significant differences, but tests on daily flows indicated that differences still exist. The overall evidence suggests that the South Fork has returned to near pretreatment conditions. Better sediment data are needed for studies of the effects of land management.

Influence of the location of production wells in unconfined groundwater basins: an analysis by numerical simulation

Development potential of groundwater resources under continuous production is calculated by numerical simulation for models of unit basins for the plains regions of Alberta, Canada, in order to analyze the relations between the location of water wells on the one hand, and well yield and basin stability, on the other. These relations are expressed in terms of two basin hydrologic parameters, namely the transitional basin yield (TBY) and the sustainable basin yield (SBY). TBY is the net cumulative inflow of water into the system, induced by and during development at a particular site, from an initial to a final steady-state condition. SBY, on the other hand, is the amount of water captured from precipitation due to production at a particular site under the newly established steady-state conditions. TBY is highest for well locations in the discharge area and decreases gradually as the sites are moved toward the recharge area. This is so because more of the naturally discharging, and thus otherwise lost, water is captured by wells located in discharge areas than by wells in recharge areas. On the other hand, SBY is greater if the wells are located in recharge areas than if they are in the discharge areas because an increasing percentage of precipitation is converted to infiltration by production wells as their locations are moved upslope in the basin. From a regional hydrological viewpoint, these are key relations in optimizing the development potential of the groundwater resources in extensive unconfined basins. Precipitation rate, simulated as maximum potential infiltration rate, is assumed to be constant over time. It is shown also that under conditions of restricted rainfall, a recharge-area development results in unstable basin-hydrological conditions sooner than when development takes place in the discharge area. Regional groundwater exploitation should, therefore, be initiated in discharge areas and moved towards recharge regions gradually, and only for compelling reasons. Factors such as precipitation rates and positions of aquifers within a basin affect TBY and SBY to various degrees, thereby influencing the optimal location of well sites in the basin.

Multiple exposure pathway risk assessment for dioxin at a bleached pulp mill

A risk assessment was performed evaluating routes of potential exposure from four activities at a bleached kraft pulp and paper mill: effluent discharge into a local river; treatment of effluent in aeration stabilization basins; irrigation of crops with effluent; and land-filling of sludge. A 3-tier ranking system was developed based on the risk or margin of safety, the quality of the data, and the sensitivity of certain data. Each exposure route was placed in an appropriate tier for environmental sampling, further research, or elimination from further consideration.

Geotechnical Characterization of Drainage Basin Stability with Respect to Debris Avalanches in Central Virginia

Many drainage basins in central Virginia experienced extensive debris avalanche activity during the heavy rainfall associated with Hurricane Camille in 1969. Forty three first-order drainage basins were randomly selected in Nelson County and classified as stable or unstable based on their values of horizontal curvature and gradient. Soils from these basins were tested for their geotechnieal properties including natural water content, grain size distribution, Atterberg limits, and in situ densities. The geotechnieal properties were then statistically analyzed to ascertain if a significant difference existed between stable and unstable basins at the 95 percent confidence level. Results indicate that the soils in stable basins generally are low plasticity silts while the soils in unstable basins predominantly are silty sands. The unstable basins are further characterized by significantly thinner soils, lower soil moisture values, lower plasticity indices, lower field densities, higher porosities, and higher void ratios. The dissimilarity in debris avalanche potential of the two basin types can be related to these differences in geotechnieal properties.

Anaerobic treatment of pulp and paper mill wastewaters

AbstractSecondary treatment of pulp and paper mill wastewaters for biochemical oxygen demand (BOD) removal worldwide has traditionally been accomplished, and particularly in North America, by aerobic treatment processes, including aerated stabilization basin and activated sludge. In recent years, however, interest in applying anaerobic processes to treat pulp and paper mill effluents has increased, with at least 25 full‐scale installations currently operating or under construction.

Seasonal and In-Mill Aspects of Organic Halide Removal by an Aerated Stabilization Basin Treating a Kraft Mill Wastewater

Levels of total organic hallde (TOX) in a Kraft mill wastewater ranged from 26,000 to 60,000 µg/l. An aerated stabilization basin (ASB) proved capable of removing one-third to one-half of both the total TOX as well as lower molecular weight (<l,000) TOX. Influent. TOX levels varied as a function of in-mill production activities. Removal of specific size fractions of of organic halide were influenced to different extents by influent variations and seasonal effects. The major removal mechanism appears to be biosorption of TOX onto settling biomass, followed by anaerobic dehalogenation within the benthal layer of the ASB.

Design of a new medium for volume holographic information processing

An optical analog of the neural networks involved in sensory processing consists of a dispersive medium with gain in a narrow band of wave numbers, cubic saturation, and a memory nonlinearity that may imprint multiplexed volume holographic gratings. Coupled-mode equations are derived for the time evolution of a wave scattered off these gratings; eigenmodes of the coupling matrix κ saturate preferentially, implementing stable reconstruction of a stored memory from partial input and associative reconstruction of a set of stored memories. Multiple scattering in the volume reconstructs cycles of associations that compete for saturation. Input of a new pattern switches all the energy into the cycle containing a representative of that pattern; the system thus acts as an abstract categorizer with multiple basins of stability. The advantages that an imprintable medium with gain biased near the critical point has over either the holographic or the adaptive matrix associative paradigms are (1) images may be input as noncoherent distributions which nucleate long-range critical modes within the medium, and (2) the interaction matrix κ of critical modes is full, thus implementing the sort of full connectivity needed for associative reconstruction in a physical medium that is only locally connected, such as a nonlinear crystal.