bluuebunny/crossref_metadata_2025 huggingface dataset:
Applicability of modelling tools in watershed management for controlling diffuse pollution
Authors: Erturk A. , Gurel M. , Baloch M.A. , Dikerler T. , Ekdal A. , Tanik A. , Seker D.Z.
Published: July 2007

Diffuse pollution is hard to analyze, control and manage by its nature. Watershed models and Geographical Information Systems (GIS) are recently developed tools that aid analysis of diffuse sources of pollution. However, their applications are not always easy and straightforward. Turkey is a typical example of a mountainous country rich in rivers and streams. Due to the complex geomorphology, land-use and agricultural practices in most of the watersheds in Turkey, modelling, analyzing and managing diffuse pollution has been a challenge. The complex watershed structure forces the modellers to work with spatially high resolution data. Apart from the data, the models themselves may also cause operational problems. These issues and their probable solutions form the basis of the discussions in this paper. It acts as a guideline for modelling and analyzing diffuse pollution by emphasizing the referred problems and difficulties. Design of an Information Technology-based system tool for watershed and/or water quality modelling, which would be suitable for countries having watersheds with similar structure and problems to those of Turkey, is also outlined.
How participatory can participatory modeling be? Degrees of influence of stakeholder and expert perspectives in six dimensions of participatory modeling
Authors: Jonsson A. , Andersson L. , Alkan-Olsson J. , Arheimer B.
Published: July 2007

The authors are involved in a project aiming at the development of a methodology for participatory modeling as a tool for public participation in water resource management. In this paper, some examples of different degrees of stakeholder influence in six key dimensions of participatory modeling are identified and discussed. Arnstein's (A ladder of citizen participation. Journal of the American Institute of Planners, 1969, 4, 216–224) critical discussion of different degrees of “real” decision-making power is taken as a point of departure to assess possible degrees of stakeholder influence. Can we as participatory modelers be sure that we are really inviting our research objects to an equal communicative relationship where local perspectives, knowledge and priorities are respected to the same extent as central and/or expert perspectives? This paper presents an approach that could be used as a tool for structured reflection to avoid unreflective tendencies towards expert knowledge dominance and low degree of stakeholders' real influence over the process.
Effectiveness of combined sewer overflow treatment for dissolved oxygen improvement in the Chicago Waterways
Authors: Alp E. , Melching C.S. , Zhang H. , Lanyon R.
Published: July 2007

An Use Attainability Analysis (UAA) has been initiated to evaluate what water-quality standards can be achieved in the Chicago Waterway System (CWS). There are nearly 200 combined sewer overflow (CSO) locations discharging to the CWS by gravity. Three CSO pumping stations also drain approximately 140 km2. Because of the dynamic nature of the CWS the DUFLOW model that is capable of simulating hydraulics and water-quality processes under unsteady-flow conditions was used to evaluate the effectiveness of water-quality improvement techniques identified by the UAA including CSO treatment. Several CSO treatment levels were applied at gravity flow CSOs to evaluate improvement in dissolved oxygen (DO). The results show that pollutant removal at CSOs improves DO to a certain degree, but it still was not sufficient to bring DO concentrations to 5 mg/L or higher for 90% of the time during wet weather at most locations on the CWS. Flow from the pumping stations results in substantial stress on DO since a huge amount of un-treated water with a high pollution load is discharged into the CWS in a short period of time at a certain location. The simulation results indicate that CSO treatment does not effectively improve DO during wet-weather periods on the CWS.
Estimation of the emission factors of PAHs by traffic with the model of atmospheric dispersion and deposition from heavy traffic road
Authors: Ozaki N. , Tokumitsu H. , Kojima K. , Kindaichi T.
Published: July 2007

In order to consider the total atmospheric loadings of the PAHs (polycyclic aromatic hydrocarbons) from traffic activities, the emission factors of PAHs were estimated and from the obtained emission factors and vehicle transportation statistics, total atmospheric loadings were integrated and the loadings into the water body were estimated on a regional scale. The atmospheric concentration of PAHs was measured at the roadside of a road with heavy traffic in the Hiroshima area in Japan. The samplings were conducted in summer and winter. Atmospheric particulate matters (fine particle, 0.6–7 μm; coarse particle, over 7 μm) and their PAH concentration were measured. Also, four major emission sources (gasoline and diesel vehicle emissions, tire and asphalt debris) were assumed for vehicle transportation activities, the chemical mass balance method was applied and the source partitioning at the roadside was estimated. Furthermore, the dispersion of atmospheric particles from the vehicles was modelled and the emission factors of the sources were determined by the comparison to the chemical mass balance results. Based on emission factors derived from the modelling, an atmospheric dispersion model of nationwide scale (National Institute of Advanced Industrial Science and Technology - Atmospheric Dispersion Model for Exposure and Risk assessment) was applied, and the atmospheric concentration and loading to the ground were calculated for the Hiroshima Bay watershed area.
The influence of stream bed hydraulic conductivity on sustaining baseflow in rivers
Authors: Gunduz O.
Published: July 2007

This study presents the results of the influence of stream bed hydraulic conductivity on baseflow sustainability by using a coupled model of surface and subsurface hydrology. The model provides a coupled solution to the dynamic interactions between a river and a surfacial aquifer and is used to numerically study the effect of stream bed conductivity on the overall system response. To achieve this objective, the model is formulated to include a one-dimensional river flow model and a two-dimensional vertically averaged groundwater flow model in an unconfined aquifer. The coupling is achieved at the river bed via a hydraulic flux that is described as a function of river bed conductivity and the gradient between river stage and groundwater head. The model incorporates the concept of simultaneous presence of the two hydrologic processes for simulating the dynamic interactions and uses a novel numerical technique to solve the two systems concurrently. These interactions are analyzed by numerical experimentation under different hydraulic conductivity conditions. The influence of hydraulic conductivity and hydraulic gradient is studied under steady and unsteady flow regimes to assess the occurrence of baseflow. The analysis also reveals critical insights into the governing mechanisms that provide and sustain the baseflow in rivers.
Anaerobic fluidized bed reactor application to tropical fruit wine effluent
Authors: Fernández N. , Montalvo S. , Guerrero L. , Sánchez E. , Cortés I. , Travieso L.
Published: July 2007

The influence of the organic loading rate (OLR), the fluidization level (FL) and the particle diameter of natural zeolite used as support (DP), was evaluated at a laboratory scale anaerobic fluidized bed reactor (AFBR), treating tropical fruit wine effluent (vinasse). The experiment was carried out at an OLR from 2–5 kg COD/m3 d, FL of 20 and 40% and DP from 0.25 to 0.80 mm. It was demonstrated that OLR and FL had a slight influence on chemical oxygen demand removal and strong influence on the methane production rate. The COD removal was slightly higher for the higher particle diameter used. Additionally using the scanning electron microscope (SEM), it was observed that natural zeolites have excellent physical characteristics as a support medium in AFBR.
Photo-Fenton processes assisted by solar light used as preliminary step to biological treatment applied to winery wastewaters
Authors: Mosteo R. , Ormad M.P. , Ovelleiro J.L.
Published: July 2007

Winery wastewaters are difficult to treat by conventional biological processes, because they are seasonal and experience substantial flow variations. Photocatalytic advanced oxidation is a promising technology for wastewaters containing high amounts of organic matter.

In this research work, solar assisted photo-Fenton processes of both heterogeneous and homogeneous phase are used in the pre-treatment of winery wastewaters. The results of these experiments have confirmed the suitability of the photo-Fenton processes, due to these treatments achieving purification levels of up to 50% (measured as total organic carbon). The intermediate effluents are treated adequately by aerobic biological treatment (activated sludge process), due to the decrease in organic matter concentration present in winery wastewaters. The possibility of a combined photo-Fenton process, based on the use of sunlight, and aerobic biological treatment (activated sludge) is suggested.
Selection of variables using factorial discriminant analysis for the state identification of an anaerobic UASB–UAF hybrid pilot plant, fed with winery effluents
Authors: Castellano M. , Ruiz-Filippi G. , González W. , Roca E. , Lema J.M.
Published: July 2007

Anaerobic wastewater treatment has become a widely used method for wastewater depuration, and has been applied in a wide range of situations, from urban wastewater to highly toxic industrial wastewater. Particularly it has been successfully applied to the treatment of the beverage industries effluents. To avoid the destabilization of the system a monitoring diagnosis and control system of the depuration processes is necessary. The cost of this system is an important issue, that depends on the number of parameters that must be controlled for an adequate performance of a wastewater plant control system. This work shows how the classic statistical classification techniques can be applied to determine the number variables that must be monitored to achieve an adequate performance of anaerobic UASB–UAF hybrid Pilot Plant monitoring and control system. The obtained results had not been unique, so different combinations of variables can be selected for a good wastewater treatment process control. Economic or technical criteria may be considered to determine the final variables set in each particular situation.
Outlet Temperature Regulation for a Class of Plug Flow Chemical Reactor via Nonlinear Feedback
Authors: Aguilar-López Ricardo
Published: July 2007

The aim of this paper is the regulation of the temperature, at outlet conditions, for a class of plug flow chemical reactors. The considered reactor is modeled by a set of hyperbolic partial differential equations, as related to mass and energy balances, with consideration that the measured output for this kind of systems is the outlet temperature, as is usual with industrial practice. It is proposed that in nonlinear feedback which contains a proportional contribution of the named regulation error plus a high order sliding-mode term-to-tray to compensate for the convective transport, the nonlinear terms and disturbances employing the stabilizing effects of the sliding modes have a satisfactory performance. A theoretical frame for the stabilization properties of the proposed controller is provided and numerical simulations illustrate the corresponding performance, which is compared with a well tuned PI control law.
Visualization of the Effect of a Shroud on Entrainment of Fluidized Solids into a Gas Jet
Authors: Hulet Craig , McMillan Jennifer , Briens Cedric , Berruti Franco , Chan Edward W
Published: July 2007

Submerged gas jets issuing into fluidized beds are used in many different industries and it is important to have a fundamental understanding of how the gas and surrounding medium interact  to understand the flow patterns and how the solids behave in the vicinity of the nozzle jet. Following the discussions of Bohnet and Teifke (1985) and Idelchek (1994) it was decided to qualitatively investigate the effects of altering the region surrounding the contact between the jet and the fluidized bed. Alteration of the flow pattern was accomplished using a semi-cylindrical shroud (0.035 m i.d. and 0.043 m long) that formed a physical barrier around the nozzle tip. The nozzle inner diameter was 0.0016 m i.d. and the motive gas flow rate was supersonic. Videos were recorded of the solids and gas flow patterns via a special transparent plate on the wall of the fluidized bed for a half-jet with and without a shroud at a superficial fluidization gas velocity of 0.11 m/s. Presented below are the original videos and observations derived from the two simple experiments in a fluidized bed with a rectangular cross-section (0.10 by 1.20 m and 2.0 m high). There was a significant difference in the flow patterns of the solids in the vicinity of the nozzle tip when the shroud was present. Furthermore, the jet expansion angle and penetration were observed to decrease by approximately 50% and 43%, respectively.
The Fed's Real Job
Authors: Telser Lester G
Published: July 2007

Business reporters and Fed watchers focus on monetary policy which is no longer--if it ever was--the Fed's main job, according to Lester Telser. Ben Bernanke's own research suggests that even long ago the main danger to the economy came from the non-monetary effects of disruptions in confidence in the soundness of the banking system, a fact that is all the more true today.
A Study on Degradation Kinetics of Trypsin Inhibitors in Horse Gram (Dolichos biflours)
Authors: Tarade Kavita , Singhal Rekha , Jayram Radha , Pandit Aniruddha
Published: July 2007

This study aims at developing a kinetic model for the degradation of trypsin inhibitor (TI) in horse gram (Dolichos biflours) subjected to a defined set of processing conditions. The study was carried out in isothermal conditions over a temperature range of 60-120° C. The degradation of TI followed first order kinetics. It was adequately modeled by the Arrhenius equation. Using the time temperature data of the nonisothermal heating process encountered in three different cooking methods viz. open pan, pressure cooking and cooking in a recently developed and patented fuel-efficient 'EcoCooker', and the kinetic data obtained under isothermal temperature conditions, a mathematical model has been developed to predict the degradation of TI in these three modes of cooking.
Time Dependent Rheological Characteristics of Pineapple Jam
Authors: Basu Santanu , Shivhare US , Raghavan GSV
Published: July 2007

Jam is an intermediate moisture food containing fruit pulp, pectin, sugar and acid. The effect of sugar and pectin concentration, pH, shear rate and temperature on the time dependent rheological properties of pineapple jam was studied using a rheometer. Pineapple jam exhibited thixotropic behavior. Shear stress of the pineapple jam at a particular time of shearing depended on the shear rate, temperature and composition. Weltman, Hahn, and Figoni and Shoemaker, models were applied to describe the time dependent flow properties of pineapple jam. Hahn model described adequately the rheological characteristics of pineapple jam.
A Multi-Level Methodology for Conceptual Reaction-Separation Process Design
Authors: Linke Patrick , Kokossis Antonis C.
Published: July 2007

Generic technology is presented for the optimal screening of reaction and separation process interactions. The proposed scheme enables the use of particularly rich superstructure formulations that are comprised of two types of generic synthesis units with flexible representation modes. A reaction unit enables a detailed representation of the reaction and a conceptual representation of separation systems is facilitated through separation task units. Possible process design interactions are embedded in the superstructure formulations as combinations of generic units. The design options are explored using stochastic optimisation techniques suitable for this class of problems. The synthesis scheme supports the decision making process in early process design stages and prepares problem definitions for later stages. Conceptual screening functionalities reveal design insights into the performance of complex reaction-separation systems based on the limited modelling information available early in design. This enables the identification and inclusion of the relevant design information into the superstructure formulations employed in the subsequent design stages.
Nonlinear Process Operability Analysis Based on Steady-State Simulation: A Case Study
Authors: Santoso Herry , Rojas Osvaldo J. , Bao Jie , Lee Peter
Published: July 2007

In this paper, the operability of a high-purity distillation column is presented. This process is known to be difficult to control and operate due to the high degree of nonlinearity of the process. The analytical framework used to assess the process operability are the regions of steady-state attainability, recently developed by Rojas et al (2006). This framework is selected because it allows one to assess the viability of applying linear control to a nonlinear process solely based on the process nonlinear steady-state information. In this approach, two operating regions are defined in both input and output spaces, which provide an indication of the inherent difficulty of controlling the nonlinear process using linear output feedback. In order to integrate this operability analysis in process design practice, the analysis is based on a numerical steady-state simulation of the column using ASPEN PLUS®. By using ASPEN Sensitivity Analysis Tool that varies the column inputs across a pre-defined Available Input Space, the steady-state nonlinear map of the column outputs can be generated. Based on these simulation results, the regions of steady-state attainability can be obtained and used to provide insights to the operability properties of this highly non linear system.
On-Line Dynamic Data Reconciliation Incorporating Dynamic Simulation
Authors: Téllez-Schmill Rodolfo , Svrcek William Y , Young Brent
Published: July 2007

The formulations for dynamic data reconciliation found in the literature assume that the error minimization problem is solved as a non-linear optimization problem constrained by the material and energy balances in the form of time-dependant non-linear differential equations. In this paper we introduce a new approach or an unconstrained formulation of this problem using a dynamic process simulator or model calculator and its potential application to chemical process control.
Development of Heat Exchanger Fouling Model and Preventive Maintenance Diagnostic Tool
Authors: Zabiri H. , Radhakrishnan V. R. , Ramasamy M. , Ramli N. M. , Thanh V. Do , Wah C. S.
Published: July 2007

The Crude Preheat Train (CPT) is a set of large heat exchangers which recover the waste heat from product streams back to preheat the crude oil. The overall heat transfer coefficient in these heat exchangers may be significantly reduced due to fouling. One of the major impacts of fouling in CPT operation is the reduced heat transfer efficiency. The objective of this paper is to develop a predictive model using statistical methods which can a priori predict the rate of the fouling and the decrease in heat transfer efficiency in a heat exchanger in a crude preheat train. This predictive model will then be integrated into a preventive maintenance diagnostic tool to plan the cleaning of the heat exchanger to remove the fouling and bring back the heat exchanger efficiency to their peak values. The fouling model was developed using historical plant operating data and is based on Neural Network. Results show that the predictive model is able to predict the shell and tube outlet temperatures with excellent accuracy, where the Root Mean Square Error (RMSE) obtained is less than 1%, correlation coefficient R2 of approximately 0.98 and Correct Directional Change (CDC) values of more than 90%. A preliminary case study shows promising indication that the predictive model may be integrated into a preventive maintenance scheduling for the heat exchanger cleaning.
Bribery and Favoritism by Auctioneers in Sealed-Bid Auctions
Authors: Burguet Roberto , Perry Martin K
Published: July 2007

We consider a model of bribery in an asymmetric procurement auction. In return for a bribe from the dishonest supplier, the auctioneer has the discretion to allow this supplier to revise his bid downward to match the low bid of the honest supplier. The dishonest supplier can also win the contract outright without paying a bribe by bidding below the honest supplier. We investigate the effect of the bribe share and the cost distributions on the bidding functions, the allocative distortion, and the expected price paid by the buyer. The dishonest supplier bids more aggressively to win the contract outright when the auctioneer takes a larger bribe share. Bribery and the implied right of first refusal introduce a new allocative distortion in favor of the dishonest supplier. Finally, we use the power family of cost distributions to examine the expected price paid by the buyer. When the dishonest supplier has a more favorable cost distribution, there exist bribe shares sufficiently large such that the expected price paid by the buyer can actually decline as a result of bribery.
First-Degree Discrimination by a Duopoly: Pricing and Quality Choice
Authors: Encaoua David , Hollander Abraham
Published: July 2007

The paper examines under what conditions vertically differentiated duopolists engage in first-degree price discrimination. Each firm decides on a pricing regime at a first stage and sets prices at a second stage. The paper shows that when unit cost is an increasing and convex function of quality, the discriminatory regime is the unique subgame-perfect equilibrium of such two-stage game. In contrast to the case of horizontal differentiation, the discriminatory equilibrium is not necessarily Pareto-dominated by a bilateral commitment to uniform pricing. Also, the quality choices of perfectly discriminating duopolists are welfare maximizing. The paper explains why a threat of entry may elicit price discrimination by an incumbent monopolist.
Repeated Auctions with the Right of First Refusal
Authors: Chouinard Hayley H , Yoder Jonathan K
Published: July 2007

This paper characterizes a set of Nash equilibria in a first-price sealed-bid repeated auction with the right of first refusal using two bidders and asymmetric information regarding the bidders' value distributions. When contract value is constant from one auction to the next and winners' values are publicized, agents retain the value of incumbency and bids are identical to one-shot auctions. When each agent's contract values are random across auctions, agents choose to bid away the full expected value of incumbency, providing a measure of the value of information in this context.
Sunspot Rational Beliefs Structures, Equilibria and Excess Volatility
Authors: Nielsen Carsten K
Published: July 2007

In rational beliefs (RB) models there is an observed empirical distribution for the stochastic process of state variables. Many different weakly asymptotic mean stationary (WAMS) processes could have generated this empirical distribution, i.e. are consistent with it, and each of them are therefore called a rational belief.We provide a general framework for using RB in general equilibrium models. Individual rational beliefs are assumed correlated by means of sunspots which at the aggregate level lead to excess volatility.The application adapts the proof by Duffie et al (1994) of the existence of a stationary ergodic RE equilibrium to the case where agents hold rational beliefs.
On direct limit classes of algebras
Authors: Halušková Emília
Published: July 2007

We investigate classes of algebras which can be obtained by a direct limit construction from an algebra. We generalize some results from monounary algebras.
Postglacial Development of Vegetation in the Vicinity of the Wigry lake
Authors: Kupryjanowicz Mirosława
Published: July 2007

The Late Glacial and Holocene development of vegetation in the vicinity of the Wigry Lake is reconstructed using pollen analysis. The Late Glacial sediments include the Allerød and Younger Dryas chronozones. The Holocene section is complete. Pollen data combined with archaeological evidence and radiocarbon dating permit the recognition and characterisation of human influence on the local plant cover caused by settlers of Mesolithic and Neolithic cultures, by west Balts, by Grand Dukes of Lithuania and by Cameldolites order. On the basis of pollen analysis the development of aquatic and mire vegetation in the Wigry Lake is described.
Modern Aspects of Catalysis: The Spring Meeting of the Swiss Chemical Society, University of Geneva, March 9th 2007
Authors: Williams Alan F.
Published: July 2007

The 2007 Spring meeting of the Swiss Chemical Society was held at the University of Geneva on Friday March 9th. The general theme was catalysis and the different speakers covered various aspects of the field. Karl Anker Jørgensen discussed organic catalysis, and Robert
Schlögl heterogeneous catalysis. Martyn Poliakoff presented the use of supercritical solvents in catalysis and Richard Schrock discussed the homogeneous catalytic reduction of nitrogen to ammonia. Finally Sir John Meurig Thomas illustrated the many ways in which catalysis contributes
to modern life.
Design of C2-Symmetric Chiral Phase-transfer Catalysts for Practical Asymmetric Synthesis
Authors: Maruoka Keiji
Published: July 2007

A series of structurally rigid, chiral quaternary ammonium salts derived from commercially available (S)- or (R)-1,1?-bi-2-naphthol have been designed as new C2-symmetric chiral phase-transfer catalysts. These chiral organocatalysts have been successfully
applied to the highly practical asymmetric synthesis of useful organic molecules including amino acid derivatives.
Peptides as Asymmetric Catalysts for Aldol Reactions
Authors: Wennemers Helma
Published: July 2007

The article summarizes our research devoted to the development of peptidic catalysts for aldol reactions. Using the combinatorial method of 'catalyst–substrate coimmobilization' the peptides H-Pro-Pro-Asp-NH2 and H-Pro-D-Ala-D-Asp-NH2 were identified as highly
active and selective catalysts for direct aldol reactions. The results demonstrate that the higher complexity of peptides in comparison to rigid small organocatalysts can be a good trade-off for higher activity.
Physicians' Efficacy Requirements for Prescribing Medications to Persons with Alzheimer's Disease
Authors: Oremus Mark , Wolfson Christina , Bergman Howard , Vandal Alain C
Published: July 2007

Physicians (N = 803) were contacted via postal survey and given two sets of efficacy measures for drug treatments in Alzheimer's disease: (a) the time that patients spend in a mild or moderate state of disease; (b) levels of modification to disease progression in the areas of cognition, behaviour, and mood, and ability to perform basic activities of daily living. Physicians reported that they would prescribe a hypothetical, new Alzheimer's disease medication if it would allow patients to remain in their current disease state for 15 (mild) or 11 (moderate) additional months. Most physicians required a permanent halt to, or some reversal of, disease progression as a prerequisite for prescribing; a few required substantial reversal. More stringent efficacy requirements were negatively associated with physicians' current prescribing of cholinesterase inhibitors to persons with Alzheimer's disease, although the effects were either small (odds ratio = 0.99) or not statistically significant at the 5 per cent level. The results suggest that physicians with stringent efficacy requirements for clinically relevant efficacy measures are less likely to prescribe cholinesterase inhibitors.
Murine glutathione S‐transferase A1‐1 in sickle transgenic mice
Authors: Ginzburg Yelena Z. , Andorfer John H. , Rybicki Anne C. , Fabry Mary E. , Nagel Ronald L.
Published: July 2007

Patients with sickle cell anemia exhibit mild to moderate renal and liver damage. Glutathione S‐transferase A1‐1 is produced during kidney and liver damage. We hypothesized that cellular damage in sickle transgenic mice would lead to increased serum and urine murine glutathione S‐transferase A1‐1 levels. Levels of murine glutathione S‐transferase A1‐1 in the serum and urine of S+S‐Antilles, NY1DD, and control mice were measured by ELISA, which revealed that the serum of S+S‐Antilles mice, relative to controls, had elevated levels of murine glutathione S‐transferase A1‐1 (P = 0.005) as did NY1DD mice (P = 0.02, baseline vs. 2‐day hypoxia). Serum liver enzymes, such as aspartate amino transferase and alanine amino transferase, as well as lactate dehydrogenase were increased in S+S‐Antilles mice relative to controls (P = 0.000006, P = 0.0003, and P = 0.029, respectively). Urine murine glutathione S‐transferase A1‐1 of S+S‐Antilles mice, as well as NY1DD mice under hypoxic stress, was not significantly different from controls. Murine glutathione S‐transferase class‐mu was measured by ELISA in the urine of sickle transgenic mice and control mice to define the location of tubular damage at the proximal convoluted tubule; murine Glutathione S‐transferase class‐mu was below the limit of detection. These findings suggest that elevated levels of murine glutathione S‐transferase A1‐1 in the serum reflect release during liver damage and that proximal tubular damage does not lead to appreciable urinary murine glutathione S‐transferase A1‐1. Am. J. Hematol. 82:911–915, 2007. © 2007 Wiley‐Liss, Inc.
A cognitive approach to develop dynamic models: Application to polymerization systems
Authors: Lima Nádson Murilo Nascimento , Filho Rubens Maciel , Embiruçu Marcelo , Maciel Maria Regina Wolf
Published: July 2007

An alternative procedure based on cognitive approach is applied to develop dynamic models. The solution copolymerization of methyl methacrylate and vinyl acetate in a continuous stirred tank reactor is analyzed to illustrate the cognitive model development. Factorial planning was used to discriminate the process variables with higher impact on the process performance (effects) and they are used to built‐up a dynamic model based on the functional fuzzy relationship of Takagi–Sugeno type. Gaussian membership functions are considered for the cognitive sets and subtractive clustering method supplied the parameters of the premises of the model. Consequence functions are obtained through an optimization problem solved by a least square based algorithm. The kinetic parameters and reactor operating conditions are obtained from the literature and a mathematical model is considered as plant for identification data generation. Dynamic cognitive models showed satisfactory predictive capabilities and may be an interesting alternative to attack problems of modeling in chemical processes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
The development of a facet analysis system to identify and measure the dimensions of interaction in online learning
Authors: Miksa Shawne D. , Burnett Kathleen , Bonnici Laurie J. , Kim Joonmin
Published: July 2007

The development of a facet analysis system to code and analyze data in a mixed‐method study is discussed. The research goal was to identify the dimensions of interaction that contribute to student satisfaction in online Web‐supported courses. The study was conducted between 2000 and 2002 at the Florida State University School of Information Studies. The researchers developed a facet analysis system that meets S. R. Ranganathan's (1967) requirements for articulation on three planes (idea, verbal, and notational). This system includes a codebook (verbal), coding procedures, and formulae (notational) for quantitative analysis of logs of chat sessions and postings to discussion boards for eight master's level courses taught online during the fall 2000 semester. Focus group interviews were subsequently held with student participants to confirm that results of the facet analysis reflected their experiences with the courses. The system was developed through a process of emergent coding. The researchers have been unable to identify any prior use of facet analysis for the analysis of research data as in this study. Identifying the facet analysis system was a major breakthrough in the research process, which, in turn, provided the researchers with a lens through which to analyze and interpret the data. In addition, identification of the faceted nature of the system opens up new possibilities for automation of the coding process.
Physische Beobachtungen von Kometen. XI
Authors: Beyer M.
Published: July 2007

Der vorliegende Bericht schließt unmittelbar an die in Astron. Nachr. 284.112 veröffentlichten Ergebnisse an und enthält die zwischen 1955 Aug. 17 und 1957 Okt. 1 erhaltenen Beobachtungen von weiteren 9 Kometen. In zwei Fällen konnten die angezeigten Entdeckungen eines helleren Kometen nicht bestätigt werden, in einem weiteren war infolge ungünstiger Bedingungen nur eine wenig sichere Beobachtung möglich. Im übrigen wurde das Hauptgewicht wie bisher auf die Gewinnung möglichst zuverlässiger Gesamthelligkeiten des Kometenkopfes gelegt, um die mit dem wechselnden Sonnenabstand verbundene Helligkeitsentwicklung untersuchen zu können. Die Beobachtungen der letzten Jahre bestätigen die auch aus photographischen Filteraufnahmen gewonnene Erfahrung, daß die Kometen, unabhängig von ihren Größen, eine sehr verschiedenartige Beschaffenheit haben. Jedes Objekt hat seine individuelle Gestalt, die auch in den verschiedenen Sonnenabständen im wesentlichen erhalten bleibt. So unterscheiden sich die spitzen, sehr staubreichen Schweifkometen, denen eine Koma oft ganz fehlt, sehr stark von den zumeist kugelrunden, gasförmigen Köpfen mit einer sternartigen Verdichtung, aus der Bündel fadenförmiger Strahlen des CO+ fast geradlinig in den Raum gestoßen werden. Die Helligkeitsentwicklung verläuft bei der ersten Gruppe der Staubkometen wesentlich stetiger und ruhiger, was deutlich in dem zumeist niedrigeren Wert des Exponenten n (zwischen 2 und 4) zum Ausdruck kommt, wenn man die Intensitätsänderungen des Kometen in erster Näherung durch Ibeob = \]
}\rm I{_}}\rm beob {{ = \frac}}I_0 {{}}r∧n \Delta ∧2 {{
\[ darstellt. Einige Objektivprismen‐Spektrogramme, die von den sehr hellen Kometen AREND‐ROLAND (1956 h) und MRKOS (1957 d) erhalten wurden, lassen in Übereinstimmung mit den übrigen Beobachtungen auf einen überwiegenden Anteil reflektierender Teilchen auch in den Schweifen schließen.
Der Lichtwechsel von 315.1934 CMi
Authors: Richter G.
Published: July 2007

Es werden photographische und visuelle Beobachtungen sowie Lichtwechsel‐Elemente des Veränderlichen 315.1934 CMi mitgeteilt, der sich als β Lyrae‐Stern erweist.
Die Intensitätsverteilung im kontinuierlichen Spektrum von Sternen der Spektralklassen B–M (Mitteilungen des Astrophysikalischen Observatoriums Potsdam Nr. 72)
Authors: Lamla Erich
Published: July 2007

Das in verschiedenen Spektralphotometrien enthaltene Beobachtungsmaterial über die spektrale Intensitätsverteilung des verschmierten Kontinuums der Sterne der Spektralklassen B–M der Leuchtkraftgruppen I bzw. II, III und V wird dazu benutzt, mit Hilfe der bereits vorhandenen Anschlüsse der kontinuierlichen Sternstrahlung an die eines PLANCKschen Strahlers die „absoluten”︁ Intensitätsverteilungen zu erhalten. Soweit die Beobachtungen nicht ausreichen, werden diese im ultravioletten und infraroten Wellenlängenbereich durch theoretisch berechnete Intensitätsverteilungen ergänzt, so daß schließlich der Verlauf des verschmierten Kontinuums der Sternspektren im Wellenlängenbereich 300 ≦ γ ≦ 1060 mμ zur Verfügung gestellt werden kann. – Eine mittlere Beziehung zwischen dem Strahlungsstrom der Sterne und ihren Spektraltypen gibt die Möglichkeit, die „absoluten”︁ Intensitätsverteilungen in absolute Einheiten umzurechnen. — Weiterhin werden die Lage der Farbbereiche verschiedener Mehrfarbenphotometrien in bezug auf die Standard‐Intensitätsverteilungen untersucht und Zwei‐Farbenindex‐Diagramme unter Verwendung verschiedener langwelliger Farbenindizes aufgestellt, um festzustellen, wann eine bessere Trennung der Bildpunkte der Hauptreihensterne in diesen Diagrammen von denen der Riesensterne erreicht werden kann. – Abschließend wird der Intensitätsverlauf des Kontinuums des Spektrum‐Variablen α And untersucht.
Der Einfluß der Rotverschiebung auf die spektrale Intensitätsverteilung extragalaktischer Nebel
Authors: Lamla E.
Published: July 2007

Mit Hilfe einer aus den beobachteten spektralen Intensitätsverläufen von Einzelsternen verschiedener Spektraltypen und Leuchtkraftgruppen zusammengesetzten, mit der Beobachtung übereinstimmenden Intensitätsverteilung eines extragalaktischen elliptischen Nebels werden die Beziehungen zwischen den Farbenindizes bzw. den bolometrischen Korrektionen dieser Sternsysteme und der Rotverschiebung z berechnet und mit entsprechenden Beobachtungsdaten verglichen. Außerdem wird die Abhängigkeit dieser Beziehungen von der Farbklasse des jeweiligen Nebelspektrums untersucht. Dabei ergibt sich u. a., daß auf Grund der großen Unsicherheit in der Festlegung der bolometrischen Korrektion eine Entscheidung zwischen den verschiedenen Weltmodellen der relativistischen Kosmologie nicht möglich ist. Die Bestimmung der Größe der Rotverschiebung eines Nebels aus dem Verlauf seines Kontinuums ist nur im Rahmen von Mehrfarbenphotometrien eindeutig möglich.
Partikuläre Integrale von dynamischen Gleichungssystemen
Authors: Schmeidler F.
Published: July 2007

Es wird allgemein die Frage untersucht, unter welchen Bedingungen ein dynamisches System spezielle Lösungen besitzt, welche beliebig vorgegebene Bedingungen erfüllen. Als Anwendung wird die LAGRANGEsche Lösung des Dreikörperproblems neu bewiesen, bei welcher die drei Massen stets an den Ecken eines gleichseitigen Dreiecks stehen. Als weitere Anwendung wird die Existenz einer Klasse von Lösungen des ebenen Dreikörperproblems gezeigt, bei welcher die Apsidenlinien der beiden Planetenbahnen immer zusammenfallen, falls nur säkulare Störungen berücksichtigt werden.
Untersuchungen über SX Cassiopeiae. II (Mitteilungen des Astrophysikalischen Observatoriums Potsdam Nr. 80)
Authors: Günther O.
Published: July 2007

Es wird angenommen, daß die Streuung des Lichts im Gasring um die A‐Komponente–vorwiegend an freien Elektronen – 1. eine starke Randverdunkelung der A‐Komponente hervorruft, 2. im Nebenminimum merklich zur Schwächung des Lichts der G‐Komponente beiträgt und 3. zur Ausbildung der Flügel des Hauptminimums führt. Das diskutierte Modell ist durch die folgenden vorläufigen Werte charakterisiert: kvis = 0·43, kpg = 0·18; rg = 0·226; i = 84°.5; ra≥4 ⊙; rg ≈ 9 ⊙; Radius R und Dicke D des Gasrings: R = 4.65 ra, D = 2 ra; Elektronendichte Ne ≤ 1·56· 1012cm−3; Ne:Nh ≤ 1·4·103. Der hohe Ionisationsgrad erfordert die Zusatzannahme, daß die kinetische Temperatur im Gasring etwa 11000°K beträgt. Der zur Erhaltung des Gasrings notwendige Massenzufluß von der G‐Komponente her wird ≤ 8.4·1016g sec−1 geschätzt. Auf Möglichkeiten zur Prüfung des Modells durch weitere Beobachtungen wird hingewiesen.
Statistische Untersuchungen über Häufigkeit, Zonenwanderung und Lebensdauer von Sonnenflecken im 18. Aktivitätszyklus (Mitteilungen des Astrophysikalischen Observatoriums Potsdam Nr. 84)
Authors: Künzel H.
Published: July 2007

Aus der Epoche 1944.2 bis 1954.3 werden 3670 Fleckengruppen, aufgegliedert nach den verschiedenen Klassen der Aufwärtsentwicklung, auf Häufigkeit, Zonenwanderung und Lebensdauer hin untersucht. Es zeigt sich mit fortschreitender Klasse eine Abnahme der Häufigkeit. Die maximale Häufigkeit fällt für alle Klassen auf das Jahr 1947. Die Schwerpunkte der Häufigkeitsverteilungen hingegen liegen später, und zwar nimmt diese Verspätung im Sinne fortschreitender Klassen ab.

Die Zonenwanderung der Fleckengruppen in den einzelnen Klassen verläuft weitestgehend parallel, liegt jedoch für die Gesamtheit aller Fleckengruppen in niedrigeren Breiten, als nach dem Gesetz der Zonenwanderung aus der größten ausgeglichenen monatlichen Relativzahl zu erwarten ist.

Die Verweilzeiten in den einzelnen Entwicklungsstufen werden ermittelt und aus den gefundenen Werten die mittlere Lebensdauer der Fleckengruppen jeder Klasse abgeleitet. Es zeigt sich, daß in jeder Klasse die Verweilzeiten mit fortschreitender Aufwärtsentwicklungsstufe größer werden. Die Verweilzeiten ein und derselben Entwicklungsstufe werden jedoch im Sinne fortschreitender Klassen kleiner. Für die Entwicklungsstufen der Auflösungsphase wird ein dazu gegenläufiges Ergebnis gefunden.
Die Periodenänderungen von 27 Veränderlichen des Kugelhaufens M 15 (Mitteilungen der Sternwarte Babelsberg Nr. 10)
Authors: Bronkalla W.
Published: July 2007

72 Platten des Kugelhaufens M 15, die mit dem 122‐cm‐Spiegel der Babelsberger Sternwarte in den Jahren 1925 und 1933 aufgenommen wurden, dienten zur Neubearbeitung der Elemente von 27 Veränderlichen des Kugelhaufens. Die Helligkeiten, Perioden und Phasen der Veränderlichen 1–5, 10–15, 17, 18, 22–25, 30–32, 35, 38–40, 42, 43, 52 wurden bestimmt. Aus der Diskussion des gesamten Beobachtungsmaterials (1896–1956) wurden säkulare Periodenänderungen abgeleitet. Bei 19 Veränderlichen ändert sich die Periode linear mit der Zeit. Drei Veränderliche zeigen keine Änderung. Bei den restlichen fünf ist die Änderung unregelmäßig.
Untersuchung über die Doppelsternnatur der Nova DQ Herculis vor dem Ausbruch
Authors: Ahnert P.
Published: July 2007

Eine Prüfung der Aufnahmen, die in Sonneberg in den Jahren 1930 bis 1934, also vor dem Ausbruch, von der Nova DQ Herculis erhalten wurden, zeigt das Vorhandensein eines Bedeckungslichtwechsels mit einer etwas kürzeren Periode, als sie nach dem Ausbruch festgestellt wurde. Aus dem Verhältnis beider Perioden folgt unter plausiblen Annahmen der Massenverlust beim Ausbruch.
Lichtelektrische Beobachtungen und Systemkonstanten des Bedeckungsveränderlichen DM Delphini (Mitteilungen des Astrophysikalischen Observatoriums Potsdam Nr. 88)
Authors: Schneller H.
Published: July 2007

Aus 466 lichtelektrischen Beobachtungen an einem 70 cm‐Spiegel, dessen in der Institutswerkstatt konstruierte Montierung und Photometer‐Einrichtung beschrieben wird, ergibt sich eine Bedeckungslichtkurve für DM Del, die von stark deformierten Komponenten erzeugt sein muß. Nach der mit Schwierigkeiten verbundenen Rektifizierung werden aus dem zweiten Maximum allein die für die Rektifizierung nötigen Koeffizienten abgeleitet; die wahrscheinlichsten Werte der Systemkonstanten werden durch Variation des Radienverhältnisses und der Randverdunklung ermittelt. Wegen des Fehlens spektroskopischer Daten können die Massen und absoluten Dimensionen der Komponenten nicht hypothesenfrei bestimmt werden.
Zur Stabilität der Planetenatmosphären
Authors: Lohmann W.
Published: July 2007

Die häufig zitierte Bedingung für die Stabilität einer Planetenatmosphäre vm < 0.20 ve muß empirisch in vm < 0.13 ve abgeändert werden.
Erstbahnbestimmung für den Doppelstern ADS 3358 AB– C
Authors: von Finck W.
Published: July 2007

Für den visuellen Doppelstern ADS 3358 AB–C wird erstmalig eine provisorische Bahn berechnet. Mit Hilfe der neuen Bahnelemente wird versucht, die astrophysikalischen Zustandsgrößen des Systems zu bestimmen.
Mitteilungen über Veränderliche der Bamberger Himmelsüberwachung (Veröffentlichungen der Remeis‐Sternwarte Bamberg, Band V, Nr. 10)
Authors: Strohmeier W. , Knigge R.
Published: July 2007

Das Durchblinken und Bearbeiten von neuem Bamberger Plattenmaterial aus der kurzen Schönwetterperiode im Januar 1961 lieferte die folgenden Ergebnisse bezüglich 15 Neuentdeckungen, 11 Bestätigungen, 6 Bedeckungsveränderlichen und 2 Langperiodischen. Die Art der Auswertung und ihre Wiedergabe ist in früheren Veröffentlichungen des Bandes V beschrieben.
Der Breitendienst im Geodätischen Institut Potsdam
Authors: Uhink W.
Published: July 2007

Es wird über die Methode der Bearbeitung der Breitenbestimmungen mit dem unpersönlichen Astrolab DANJON in Potsdam, über die während des IGJ erhaltenen Ergebnisse und über einen Vergleich mit Beobachtungen in Paris berichtet.
Lichtelektrische Helligkeitsmessungen am Kometen 1956 h AREND‐ROLAND
Authors: Notni P.
Published: July 2007

Es werden Helligkeits‐ und Farbmessungen (4 Bereiche) des Kometen 1956 h AREND‐ROLAND mitgeteilt. Die Ergebnisse werden gemeinsam mit den Meßreihen von THIESSEN [12] und WEHLAU [14] diskutiert. Der Farbenindex B–V ist im Beobachtungsintervall praktisch konstant. Die sekundären Helligkeitsschwankungen sind auf Änderungen der Masseabgabe des Kometen zurückzuführen. Eine Korrelation zur Korpuskularstrahlung der Sonne wird vermutet (größere Helligkeit entspricht größerer Sonnenfleckenrelativzahl).
Gemeinsame Integrale ganzer Klassen von dynamischen Problemen
Authors: Schmeidler F.
Published: July 2007

Es wird gezeigt, daß HAMILTONsche Systeme immer dann Integrale, die ganzen Klassen von Potentialfunktionen gemeinsam sind, besitzen, wenn zyklische Koordinaten vorhanden sind. Mit Hilfe der von S. LIE entwickelten Theorie der Transformations‐ und Funktionengruppen werden allgemeine Kriterien aufgestellt, wie man erkennen kann, ob zyklische Koordinaten und Integrale entsprechender Art vorliegen. Die Anwendung der Theorie auf die Grundgleichungen der Stellardynamik liefert die Verifizierung der bisher bekannten Fälle, in denen die Gleichung Integrale besitzt, die von der speziellen analytischen Form der Potentialfunktion unabhängig existieren. Es wird außerdem der Beweis erbracht, daß über die bekannten Fälle hinaus keine Integrale dieser Art für die Grundgleichung der Stellardynamik möglich sind.
RR Lyrae‐Sterne vor der extragalaktischen Absorptionswolke in Microscopium
Authors: Hoffmeister C.
Published: July 2007

Von 93 untersuchten Veränderlichen in der Gegend von ι Mic gehören 65 dem RR Lyrea‐Typus an. Sie verteilen sich gleichmäßig über den Bereich der Absorptionswolke und ihre Umgebung, womit gezeigt ist, daß die Wolke jenseits des galaktischen Halos liegt.
Untersuchungen über Reflexionsnebel am Palomar Sky Survey. I. Verzeichnis von Reflexionsnebeln
Authors: Dorschner J. , Gürtler J.
Published: July 2007

Der Palomar‐Sky‐Atlas wurde nach Reflexionsnebeln durchmustert. Die ingesamt 192 gefundenen Nebel wurden in einer Liste zusammengestellt.
Zur Beschleunigung senkrecht zur galaktischen Ebene und zur Häufigkeit des interstellaren H2‐Moleküls
Authors: Dorschner J. , Gürtler J. , Schmidt K.‐H.
Published: July 2007

Die Beschleunigung senkrecht zur galaktischen Ebene Kz(z) wird aus der räumlichen Verteilung und den Radialgeschwindigkeiten des interstellaren HI‐Gases und der δ Cephei‐Veränderlichen für kleine Abstände von der Milchstraßenebene berechnet. Der ermittelte Verlauf von Kz(z) wird an die Ergebnisse von YASUDA und OORT angepaßt und zur Bestimmung der Dichteverteilung senkrecht zur galaktischen Ebene verwendet. Diese Dichteverteilung kann verstanden werden, wenn der Anteil des molekularen interstellaren Wasserstoffs etwa 80% der gesamten interstellaren Wasserstoffmenge ausmacht und die gleiche räumliche Verteilung aufweist wie das HI‐Gas.
Bemerkungen Über Hauptreihensterne oberhalb des Abknickpunktes in einigen älteren Sternhaufen
Authors: Dorschner J. , Gürtler J. , Schmidt K.‐H.
Published: July 2007

Es wird versucht, die bei einigen älteren Sternhaufen beobachteten Sterne auf der Hauptreihe oberhalb des Abknickpunktes durch Accretion‐Effekte zu erklären. Die Ergebnisse stehen nicht im Widerspruch zur Beobachtung.