bluuebunny/crossref_metadata_2025 huggingface dataset:
Hormesis, hotspots and emissions trading
Authors: Wiener Jonathan B
Published: June 2004

Instrument choice - the comparison of technology standards, performance standards, taxes and tradable permits - has been a major topic in environmental law and environmental economics. Most analyses assume that emissions and health effects are positively and linearly related. If they are not, this complicates the instrument choice analysis. This article analyses the effects of a nonlinear dose-response function on instrument choice. In particular, it examines the effects of hormesis (highdose harm but low-dose benefit) on the choice between fixed performance standards and tradable emissions permits. First, the article distinguishes the effects of hormesis from the effects of local emissions. Hormesis is an attribute of the dose-response or exposure-response relationship. Hotspots are an attribute of the emissions-exposure relationship. Some pollutants may be hormetic and cause local emissions-exposure effects; others may be hormetic without causing local emissionsexposure effects. It is only the local exposure effects of emissions that pose a problem for emissions trading. Secondly, the article shows that the conditions under which emissions trading would perform less well or even perversely under hormesis, depend on how stringent a level of protection is set. Only when the regulatory standard is set at the nadir of the hormetic curve would emissions trading be seriously perverse (assuming other restrictive conditions as well), and such a standard is unlikely. Moreover, the benefits of the overall programme may justify the risk of small perverse effects around this nadir. Thirdly, the article argues that hotspots can be of concern for two distinct reasons, harmfulness and fairness. Lastly, the paper argues that the solution to these problems may not be to abandon market-based incentive instruments and their cost-effectiveness gains, but to improve them further by moving from emissions trading and emissions taxes to risk trading and risk taxes. In short, the article argues that hormesis does not pose a general obstacle to emissions trading or emissions taxes, but that in those cases where hormesis does pose such a problem, a shift toward risk trading or risk taxes would be the superior route.
Village politics, culture and community-driven development: insights from Indonesia
Authors: Bebbington Anthony , Dharmawan Leni , Fahmi Erwin , Guggenheim Scott
Published: June 2004

Local governance arrangements often reflect culturally charged struggles for power as well as culturally motivated efforts to gain access to power. Yet current discussions around community-driven and decentralized development pay little attention to this nexus, at best reducing power to questions of material difference but overlooking the ways in which governance arrangements are contested. On the basis of research across three sites in Indonesia, this paper explores ways in which tensions between different cultural forms at a village level affect local governance arrangements. The conclusions explore implications for so-called community-driven approaches to development.
Chemotherapy With or Without Radiotherapy in Limited-Stage Diffuse Aggressive Non-Hodgkin's Lymphoma: Eastern Cooperative Oncology Group Study 1484
Authors: Horning Sandra J. , Weller Edie , Kim KyungMann , Earle John D. , O'Connell Michael J. , Habermann Thomas M. , Glick John H.
Published: June 2004

Purpose

To compare low-dose (30 Gy) radiotherapy (RT) with observation (OBS) in limited-stage aggressive lymphoma patients achieving complete remission (CR) after chemotherapy, and to measure conversion from partial response (PR) to CR with high-dose (40 Gy) RT.

Patients and Methods

From 1984 to 1992, stage I (with risk factors) and II adults with diffuse aggressive lymphoma in CR after eight cycles of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) were randomly assigned to 30 Gy involved-field RT or OBS. PR patients received 40 Gy RT.

Results

Among 172 CR patients, the 6-year disease-free survival (DFS) was 73% for low-dose RT versus 56% for OBS (two-sided P = .05). Failure-free survival (two-sided P = .06), and time to progression (two-sided P = .06) also favored RT. Intent-to-treat analyses yielded similar results. No survival differences were observed. Three RT versus 15 OBS patients relapsed in initial disease sites. At 6 years, failure-free survival was 63% in PR patients; conversion to CR did not significantly influence clinical outcome.

Conclusion

For patients in CR after CHOP, low-dose RT prolonged DFS and provided local control, but no survival benefit was observed. The majority of PR patients were event-free at 6 years despite residual radiographic abnormalities. Future efforts should be directed toward improved imaging and more effective systemic therapies.
Safety, Pharmacokinetics, and Activity of ABX-EGF, a Fully Human Anti–Epidermal Growth Factor Receptor Monoclonal Antibody in Patients With Metastatic Renal Cell Cancer
Authors: Rowinsky Eric K. , Schwartz Garry H. , Gollob Jared A. , Thompson John A. , Vogelzang Nicholas J. , Figlin Robert , Bukowski Ronald , Haas Naomi , Lockbaum Pamela , Li Yu-Ping , Arends Rosalin , Foon Kenneth A. , Schwab Gisela , Dutcher Janice
Published: June 2004

Purpose

To determine the antitumor activity of ABX-EGF, a fully human monoclonal antibody to the epidermal growth factor receptor (EGFr), in previously treated patients with metastatic renal cell carcinoma, and to characterize its toxicity, immunogenicity, pharmacokinetics, and pharmacodynamics.

Patients and Methods

The antitumor activity, as well as the toxicity, pharmacokinetics, pharmacodynamics, and immunogenicity of ABX-EGF, were assessed.

Results

Eighty-eight patients were treated with ABX-EGF doses of 1.0, 1.5, 2.0, or 2.5 mg/kg weekly with no loading dose. EGFr immunostaining was performed on 76 tumor biopsy specimens (86%), and 69 (91%) scored positive. Major responses occurred in three patients, and two patients had minor responses. Forty-four patients (50%) also had stable disease at their first 8-week assessment, and the median progression-free survival (PFS) was 100 days (95% CI, 58 to 140 days). Low hemoglobin and high alkaline phosphatase predicted for short PFS. The principal toxicity, an acneiform rash, occurred in 68%, 95%, 87%, and 100% of patients who received at least three doses of ABX-EGF at 1.0, 1.5, 2.0, and 2.5 mg/kg/wk, respectively. A trend indicated that the severity of the rash may relate to PFS. No human antihuman antibodies were detected. ABX-EGF pharmacokinetics fit a model that incorporated both linear and saturable EGFr-mediated clearance mechanisms, and interindividual variability was low. At 2.5 mg/kg/wk, ABX-EGF concentrations throughout treatment exceeded those estimated to saturate nonlinear clearance and inhibit xenograft growth by 90%.

Conclusion

ABX-EGF was generally well tolerated. The objective response rate was low in previously treated patients with metastatic renal cell carcinoma. Although skin rash may be a pharmacodynamic marker of drug action, its potential as a surrogate marker of clinical benefit requires further evaluation.
Preoperative Uracil, Tegafur, and Concomitant Radiotherapy in Operable Rectal Cancer: A Phase II Multicenter Study With 3 Years' Follow-Up
Authors: Fernández-Martos Carlos , Aparicio Jorge , Bosch Carles , Torregrosa Marilo , Campos Juan Manuel , Garcera Salvador , Vicent Jose Maria , Maestu Inmaculada , Climent Miguel Angel , Mengual Jose Luis , Tormo Alejandro , Hernandez Ana , Estevan Rafael , Richart Jose Maria , Viciano Vicente , Uribe Natalia , Campos Jorge , Puchades Ramon , Arlandis Francisco , Almenar Daniel
Published: June 2004

Purpose

To assess tolerance and efficacy of preoperative treatment with uracil/tegafur and radiotherapy (RT) followed by surgery and postoperative flurouracil (FU)/leucovorin (LV) in patients with rectal cancer.

Patients and Methods

Patients (n = 94) with potentially resectable tumors, ultrasound at stages T2N+ (n = 4), T3 (n = 77), T4 (n = 13) were treated with UFT (400 mg/m2/d, 5 days a week for 5 weeks) and concomitant RT to the pelvis (45 Gy; 1.8 Gy/d over 5 weeks). Patients underwent surgery 5 to 6 weeks later followed by four cycles of FU/LV. Primary end points included downstaging, pathologic responses, and sphincter-preserving surgery. Secondary end points were recurrence-free survival and overall survival.

Results

All patients received the full RT dose. Fifteen patients (16%) needed UFT dose reduction. Preoperative G3+ toxicities included diarrhea (14%), leukopenia (1%), thrombocytopenia (1%), and nausea (4%). The downstaging rate was 54%, pathologic complete response (pCR) was 9% and, in an additional 23%, there were only residual microscopic foci. When cellular viability criteria were taken into account, the pCR was 15%. From 43 patients with abdominoperineal resection indication, 11 (25%) had sphincter-preserving surgery performed. Postoperative scheduled chemotherapy dose was not administered to 24% of patients because of G3+ toxicity (diarrhea, 8%; mucositis, 9%; and leukopenia, 7%). Patients with downstaging had significantly higher survival and recurrence-free survival rates than those without. At 3 years, actuarial patterns of failure were pelvic, 5% and distant, 11%. OS was 75%.

Conclusion

UFT combined with RT is safe and effective. In resectable rectal cancer, if preoperative treatment is considered, this approach can be an option.
Simulation Model of an Active-Stall Fixed-Speed Wind Turbine Controller
Authors: Jauch Clemens , Hansen Anca D. , Sørensen Poul , Blaabjerg Frede
Published: June 2004

This paper describes an active-stall wind turbine controller. The objective is to develop a general model of an active stall controller in order to simulate the operation of grid connected active stall wind turbines. The active stall turbine concept and its control strategies are presented and evaluated by simulations. The presented controller is described for continuous operation under all wind speeds from start-up wind speed to shut down wind speed. Due to its parametric implementation it is general i.e. it can represent different active stall wind turbine controllers and can be implemented in different simulation tools.
Dynamic Loosening of Threaded Fasteners
Authors: Pai N. G. , Hess D. P.
Published: June 2004

A study on loosening of threaded fasteners subjected to dynamic shear loads is presented. A fundamental analysis of loosening reveals that a fastener can loosen at lower loads than previously expected due to localized slip at the contact surfaces. Four different loosening processes of a screw under different conditions of slip at the head and thread contact regions are identified. Experimental results illustrating these loosening processes are presented.
Analysis of Friction Induced Disc Brake Noise Using Simple Mathematical Models
Authors: Shin K.
Published: June 2004

Two simple two-degree-of-freedom models are presented to describe the dynamical interaction between the pad and the disc of a disc brake system for in-plane and out-of-plane vibrations respectively. Although a brake pad and disc have many modes of vibration, the interaction between a single mode of each component is considered as this is thought to be crucial for brake noise. For both models, the pad and the disc are connected by a sliding friction interface having a velocity dependent friction coefficient.

The results of stability analysis show that damping is the most important parameter in the in-plane vibration, whereas stiffness is the essential parameter in the out-of-plane vibration. Also, Non-linear analysis shows that the addition of damping to either the disc or the pad alone may make the system more unstable in the case of the in-plane vibration.
Describing Technological Development with Quantitative Models
Authors: Jensen Stine Grenaa
Published: June 2004

Up until now, the experience curve has been used as instrument for predicting development in costs of renewable energy technologies. This feature has been used several times in long-term optimisation models, where the experience curve describes technological development in the form of cost reduction over a long period of time. Considering long prediction periods expresses the need for relatively good estimation methods. This along with the increased knowledge of innovation theory has called for a discussion of models to describe cost reduction in order to have more precise predictions. This article aims at a discussion of three methods to describe the development, using the case study of Danish wind power. Therefore, the key result is a list of different models and their pros and cons with respect to the selection of quantitative models describing technological development in the form of cost reduction.
A Survey of Solutions and Options for the Integration of Distributed Generation into Electricity Supply Systems
Authors: ten Donkelaar Michael
Published: June 2004

Since a number of years the role of distributed generation (DG) technologies, connected directly to distribution networks, is emerging because of its expected flexibility in increasing generation capacity, its environmental benefits, and due to advancements in technology development. DG facilities are now connected at sites that were originally not meant to connect a large number of power generation facilities. This can increase the burden on the distribution network in terms of stability and power quality. At the same time existing network regulation does not enable a proper valuation of costs and benefits. Two European research projects aim to tackle these issues from a both technical and socio-economic viewpoint. The conclusion is that to facilitate a major increase of the DG share in electricity supply systems, a proper allocation of costs and benefits between different functions in the electricity system (generation, trade, transmission / distribution, consumption) will be necessary.
Effect of fluid properties on mass transfer in the gas phase
Authors: Lynch E. J. , Wilke C. R.
Published: June 2004

Water was vaporized into air, helium, and Freon‐12 in turbulent gas flow over a wet‐bulb thermometer and through a 1‐ft.‐diam. tower packed with 1‐in. Rasching rings.

The wet. and dry‐bulb measurements indicate that the gas‐film mass transfer coefficient varies with the Schmidt number to the —1/2 power for flow perpendicular to single cylinders.

Heights of a transfer unit, H.T.U., were measured in the packed tower for flow of the gases countercurrent to water over a range of gas and liquid rate. H.T.U. varied as the 0.9 power of the Schmidt group. When compared at equal values ofρu2(ρ = gas density,u= velocity), H.T.U. varied as the 0.47 power of the Schmidt group. With reference to the psychrometric study, the latter method of comparison of H.T.U.'s seems preferable and indicates that further study of criteria for dimensional similitude in packed columns may be needed.
A technique for contacting gases with coarse solid particles
Authors: Mathur K. B. , Gishler P. E.
Published: June 2004

Although coarse, uniformly sized particles are not amenable to fluidization, it has been found possible by use of either gases or liquids to impart a regular cycling motion to a bed of this type of material in which the solids are rapidly carried upward by the fluid in a central well‐defined core within the bed. The particles move uniformly downward in the annular space surrounding the core, thus providing dense‐phase countercurrent contact between the fluid and the solids. There is no wall separating the core from the annulus. This method is called the spouted‐bed technique. The effect of column diameter, fluid inlet diameter, bed depth, and physical properties of solids and fluids on spouting behavior has been investigated. The minimum fluid velocity required for spouting has been correlated, and the flow pattern of the fluid and of the solids has been stuided. The technique has been applied to the drying of wheat.
Performance of packed columns. I. Total, static, and operating holdups
Authors: Shulman H. L. , Ullrich C. F. , Wells N.
Published: June 2004

Total and static holdups have been measured for 1/2‐, and 1‐in. ceramic Berl saddles, 1/2‐, 1‐, and 1 1/2‐in. ceramic Raschig rings, and 1‐in. carbon Raschig rings with air rates from 100 to 1,000 1b./(hr.) (sq. ft.) and water rates from 1,000 to 10,000 1b./ (hr.) (sq. ft.).

The holdup measurements and motion picture observations of the flow of dye solutions through packings provide an explanation for the great differences observed when gas‐phase mass transfer rates are measured by absorption and vaporization methods. If the effective interfacial area for vaporization is assumed to be proportional to total holdup and the area for absorption is assumed proportional to operating holdup, the raio of the two mass transfer rates should be equal to the ratio of the two holdups.

The departure from equality of the two ratios can be explained by the observation that the static holdup is displaced slowly, resulting in additional effective area for absorption over that expected from the operating holdup alone.
Performance of packed columns. II. Wetted and effective‐interfacial areas, gas ‐ and liquid‐phase mass transfer rates
Authors: Shulman H. L. , Ullrich C. F. , Proulx A. Z. , Zimmerman J. O.
Published: June 2004

A study was made of separating the volumetric mass transfer coefficients, kGa and kLa, into their components kG, kL, and a so that the effects of variables might be determined separately for each component. Mass transfer rates for four packings, 1/2‐ and 1 1/2‐in. Raschig rings and 1/2‐in. and 1‐in. Berl saddles, made of naphthalene, were determined by vaporization into air at gas rates from 100 to 1,000 1b./(hr.) (sq. ft.).

The correlation for kGa was used to determine the wetted areas of those packings when irrigated with water and to calculate the effective interfacial areas, a, from Fellinger's data for ammonia absorption. These effective areas were then used to evaluate kL from previously published kLa data, and a correlation was obtained for all packings.

The correlations for kGa and kLand the effective‐interfacial‐area data make possible a more rigorous method for the design of packed columns than was heretofore available.
Rate of fall of single liquid droplets
Authors: Licht William , Narasimhamurty G. S. R.
Published: June 2004

A study was made of the terminal velocities of fall of liquid droplets in another phase liquid under stationary conditions. The studies include dimensional analysis, experimental work for collection of fall‐velocity data, and photographic studies of the drop behavior. Six systems were studied for organic liquids insoluble in and heavier than water. The experimental conditions and procedure have been standardized.

For any given system, as the drop size was increased the fall velocities of the droplets increased gradually, reached a maximum, and then fell off asymptotically. Two mechanisms have been postulated, (1) for the range where the fall velocities increased with an increase of drop size and (2) for the range where the fall velocities decreased with an increase of drop size, with the maximum velocity region corresponding to the transition from region 1 and 2.
Transient behavior of single‐phase natural‐circulation loop systems
Authors: Alstad C. D. , Isbin H. S. , Amundson N. R. , Silvers J. P.
Published: June 2004

A useful method is reported for calculating temperatures and rates of flow in the unsteady‐state operation of natural‐circulation loops in single phase. A one‐dimensional mathematical model is used with the assumptions that (1) at any instant the volumetric rate of flow is constant around the loop and (2) steady‐state friction factors can be applied in transient operations. The loop, consisting of a heat source, heat sink, hot leg, cold leg, and connecting piping, is divided into a number of finite increments. The transient behavior is calculated by the iterative application of the finite‐difference momentum and energy balances. Numerical computations made for several cases of transient operations were carried out with the aid of the Standard Eastern Automatic Computer (SEAC).

Comparisons of predicted with actual performances were checked by use of two experimental loops employing water and found satisfactory.
Chemical reactor stability and sensitivity
Authors: Bilous Olegh , Amundson Neal R.
Published: June 2004

The purpose of this paper is to consider the well agitated continuous reactor from the standpoint of stability of the steady state. It has been shown in the past that chemical‐reaction systems may be unstable in the sense that on slight perturbation they tend to move to a more stable state or that they are stable in their steady states, small perturbations being self‐correcting so that the system possesses autoregulation. In this paper methods of developing criteria for the quantitative determination of stability or instability or presented and applied to some simple problems. In order that the effect of large perturbations on the system may be determined, complete solutions of the rigorous equations are obtained on the analogue computer (R.E.A.C.). A complete plot of reaction paths in the concentration‐temperature plane may be obtained in this manner. Because of the nonlinearity of the system one cannot predict with certainty what steady state will be approached after a given large perturbation, multiple steady states being assumed possible. From the phase plot of reaction paths the regions in the plane which lead to certain steady states are delineated. Also it is shown that the natural behavior of a reactor is not to approach an unstable state. So far as the reactor is concenrned, the unstable state does not exist. The stability of the system is important to the engineer, as control will be easy or difficult and product quality will be satisfactory or not depending upon the relative stability of the steady state. An unstable state would require more elaborate control than a stable state.
Equivalent isothermal temperatures for nonisothermal reactors
Authors: Malloy John B. , Seelig Herman S.
Published: June 2004

A simple procedure has been developed for evaluating the equivalent isothermal temperature for nonisothermal reactors. Reaction‐rate constants determined from a kinetic study are averaged by a simplified integration method; the average rate constant defines the equivalent isothermal temperature. Use of this equivalent temperature permits direct comparison of experiments carried out in reactors having widely different temperature profiles.
Oscillatory behavior of a two‐phase natural‐circulation loop
Authors: Wissler Eugene H. , Isbin H. S. , Amundson N. R.
Published: June 2004

A natural‐circulation loop with water as the circulating fluid was studied for a range of operation covering two‐phase flow. The work reported in this paper is concerned with the periodic oscillations of the flow rate and fluid temperature. The oscillations occurred even with constant heat input and constant cooling‐water properties for the heat exchanger. The analytical approach includes a theoretical analysis of an open‐ended system and numerical solutions obtained with an analogue computer for a simplified loop system. Also presented are the equations of motion, continuity, and energy, which were developed for a transient two‐phase flow model for adaptation to more detailed numerical evaluations.
Flow distribution among parallel heated channels
Authors: Gruber Alan R. , Hyman Seymour C.
Published: June 2004

The coolant flow distribution among parallel tubes in a nuclear reactor (or boiler or heat exchanger) can be very sensitive to variations in heat input, dimensions, etc. Analytical expressions are given for partial derivatives which measure flow variations for several situations. The utility of orifices and valves in reducing flow sensitivity is discussed. Numerical results are reported for a system using water at supercritical pressurs with an eightfold expansion from inlet to outlet.
A system for counting variables in separation processes
Authors: Kwauk Mooson
Published: June 2004

In the proposed system for counting variables in separation processes the processes are resolved into their simpler component classes, e.g., theoretical plates, heat exchangers, reboilers, distillation columns, etc., and a distinction is made between those variables which are inherent in the systems and those which may be specified for design. Results are presented for the most commonly occurring component classes, and all possible process relations existing among these classes are expressed by a set of generalized equations [(16) to (19)]. The procedure of counting variables is therefore reduced to compositon from variables for the component classes by use of the generalized equations.
Role of eddy conductivity in thermal transport
Authors: Corcoran W. H. , Sage B. H.
Published: June 2004

Interest in the course of chemical reactions in turbulent flow has made desirable detailed knowledge of the temperature distribution in flowing streams. One method of predicting the temperature distribution under a variety of conditions is reviewed here, the approach being limited to conditions of local uniform transport of momentum. A discussion of some of the aspects of eddy conductivity is included along with a brief review of the velocity distribution in uniform flow.

The results serve to illustrate the relation of microscopic conditions of flow to the temperature distribution in a turbulently flowing stream. The importance of the molecular Prandtl number upon the transfer process is stressed.
Structure and performance of filter media. I. The internal structure of filter media
Authors: Grace H. P.
Published: June 2004

The internal structure of various types of filter media and the nature of fluid flow through them are examined. Methods of characterizing the internal pore structure of filter media are reviewed, and the permeability, bubble‐pressure, and mercury‐intrusion methods are applied to ten typical media, with resulting values of average and maximum pore radius and pore‐size distribution being reported. These data on internal pore structure are related to the construction variables characteristic of the media examined, in particular the effect of yarn construction, yarn twist, fabric weave, and fabric finish on textile‐type filter media.
Effect of wall proximity on the rate of rise of single air bubbles in a quiescent liquid
Authors: Uno Seiji , Kintner R. C.
Published: June 2004

The terminal velocity of air bubbles rising through distilled water, 61% glycerine, diethylene glycol, and a solution of a surface‐active agent was measured in vertical cylindrical tubes of 2.09, 3.64, 4.91, 6.90, 9.50, and 15.25 cm. avg. I.D. An equation was developed to express a velocity‐correction factor in terms of the ratio of bubble diameter to tube diameter and an empirical constant. The constant was a function of tube diameter and of the surface tension of the liquid. It seemed to be independent of liquid viscosity.
Heat transfer to non‐newtonian fluids
Authors: Metzner A. B. , Vaughn R. D. , Houghton G. L.
Published: June 2004

This paper presents the first theoretical analyses combined with an experimental study of the variables controlling heat transfer rates to non‐Newtonian fluids in the streamline‐flow region. The theoretical analyses, for the limiting types of non‐Newtonian materials, were related to the intermediate case of Newtonian behavior to form a coherent theory applicable to Newtonian and non‐Newtonian fluids alike.

The experimental data covered Graetz numbers between 100 and 2,000 and were correlated with a mean deviation of 13.5%. The flow‐behavior indexes of the three non‐Newtonian fluids used varied form 0.18 to 0.70.

Some preliminary non‐Newtonian results are presented on the problems of nonisothermal fluid‐flow pressure losses and heat transfer outside the laminar‐flow region. Further theoretical work is recommended in both these areas. Additional experimental data would be of value in all of the problems discussed.
Mass and heat transfer from drops in liquid‐liquid extraction
Authors: Handlos A. E. , Baron T.
Published: June 2004

Mass and heat transfer rates in extraction are studied theoretically and experimentally for the practical range of the variables involved. For the particular but typical case of liquid drops moving through another liquid a simple correlation for the over‐all mass transfer coefficient is presented, which holds with a probable error of 20%.

Included are systems in which the rate is limited by either coefficient, as well as systems in which both coefficients are significant. The correlation, valid for both directions of transfer with either phase dispersed, is useful for the extrapolation of performance from system to system in a given piece of equipment. Also, together with correlations for transfer area and effective driving force, it is part of the information needed for design.
Froth‐frothate concentration relations in foam fractionation
Authors: Kevorkian Victor , Gaden Elmer L.
Published: June 2004

Concentration relations between foams and their residual liquids (frothates) have been examined.

Clean air streams of 88, 91, and 96% water saturation were bubbled into aqueous solutions of isobutyl alcohol. The concentration of the alcohol in the collected and collapsed foam was plotted against its concentration in the bulk liquid.

Varying the saturation of the air stream resulted in both positive and negative enrichment of the foam with the surface‐active alcohol. This suggests that where froth‐frothate‐concentration relations are unfavorable, a change in operating conditions may advantageously affect these relations and allow the mixture to be foam separated.
Interaction between a turbulent air stream and a moving water surface
Authors: Hanratty Thomas J. , Engen James M.
Published: June 2004

The interaction between a turbulent air stream and a water film flowing parallel to it was studied. The variables explored were the liquid flow rate, the gas flow rate, and the film height. The data were correlated in terms of a liquid and a gas Reynolds number. Thinner films or films having a lower Reynolds number were more stable. For the experiments reported in this research the transition from a smooth surface to a surface possessing two‐dimensional waves occurs at hUτρliquid/µliquid of about 520. Transition from two‐dimensional waves to a “pebbled” surface occurs at a value of this parameter of about 600. Theories presented in the literature for the initiation of waves on a liquid surface do not adequately describe the experimental results.
Evaluation of the heat requirements in batch distillation operations
Authors: Stiehl J. G. , Weber James H.
Published: June 2004

A rigorous method is presented for the evaluation of the heat requirements in binary batch fractionations which involve negligible column hold up. The method, in which the additional variables of the discontinuous process are taken into account, is a modification of the methods of Ponchon and Savarit for continuous operation. Two examples, one for a fractionation in which the composition of the product is constant and the other in which the reflux ratio is constant, are given as illustrations of the method.

The application of the method permits more accurate evaluation of reboiler and condenser heat loads and, in turn, better design.
Liquid‐liquid extraction accompanied by chemical reaction
Authors: Fujinawa K. , Maruyama T.
Published: June 2004

From time to time, A.I.Ch.E. Journal is going to present translations of certain technical articles written by our Japanese colleagues in their own language. These translations are to be made by Kenzi Etani, who received his B.S. in chemical engineering in 1953 at the Tokyo Institute of Technology and his M.S. in 1955 at M.I.T. He is associated with Stone & Webster and is an associate member of American Institute of Chemical Engineers. He is also a member of the Society of Chemical Engineers, Japan, and the Japan Oil Chemists' Society. His offer to help break down the language barrier is acknowledged.

The following article (two will follow in the September and December issues, respectively) was published in Chemical Engineering (Japan), volume 21, pages 75—79 (1957).

Abstracts, notation, literature cited, tables, and figure captions not published here appear in English in the original paper. No figures will be be reproduced in these translations.
Regular solution theory for gas‐liquid solutions
Authors: Prausnitz J. M.
Published: June 2004

Regular‐solution equations developed by Hildebrand and others are useful for obtaining semiquantitative estimates of phase equilibria in nonpolar systems. These equations, however, do not take into account the volume change on mixing and therefore require modification for solutions of gases in liquids. The required modifications are presented in this paper, and the resulting equations give reasonable estimates of the solubilities of gases and of the temperature coefficient of solubility. In the modified form the regularsolution theory may be used to estimate gas‐liquid phase equilibria at high pressures.
A general index of fractional distillation power for hydrocarbon mixtures
Authors: Geddes R. L.
Published: June 2004

Results from precise calculations for fractionation of multicomponent hydrocarbon mixtures show that the relative separations between components are rationalized in a simple manner in terms of the relative volatilities. A quantitative criterion for sharpness of fractionation with complex mixtures, the Fractionation Index, is suggested. This function is useful for general correlation purposes. It also enables prediction of the detailed compositions of the products from a proposed fractionation and thereby simplifies the computation procedures.
Axial mixing and extraction efficiency
Authors: Sleicher C. A.
Published: June 2004

The effect of back mixing of either phase in an extraction column, which decreases the extraction efficiency, is analyzed theoretically by means of an idealized diffusion model that can be characterized by four dimensionless parameters: a Peclet number of each phase, a mass transfer number, and the usual extraction factor. Calculations for a wide range of these parameters were performed on a digital computer.

The principal results, presented in a table, will be useful in the design and scale up of extraction columns and in the interpretation of experimental results from extractors and from some reactors in which a first‐order reaction occurs.
Turbulent flow of non‐newtonian systems
Authors: Dodge D. W. , Metzner A. B.
Published: June 2004

A theoretical analysis for turbulent flow of non‐Newtonian fluids through smooth round tubes has been performed for the first time and has yielded a completely new concept of the attending relationship between the pressure loss and mean flow rate. In addition, the analysis has permitted the prediction of non‐Newtonian turbulent velocity profiles, a topic on which the published literature is entirely silent.

To confirm the theoretical analysis, experimental data were taken on both polymeric gels and solid‐liquid suspensions under turbulent‐flow conditions. Fluid systems with flow‐behavior indexes between 0.3 and 1.0 were studied at Reynolds numbers as high as 36,000. All the fully turbulent experimental data supported the validity of the theoretical analysis. The final resistance‐law correlation represents a generalization of von Karman's equation for Newtonian fluids in turbulent flow and is applicable to all non‐Newtonians for which the shear rate depends only on shear stress, irrespective of rheological classification. All the turbulent experimental data for the non‐Newtonian systems were correlated by this relationship with a mean deviation of 1.9%.
Studies on entrainment
Authors: Aiba Shuichi , Yamada Toyokazu
Published: June 2004

After application of a biochemical technique, size distribution of liquid drops from air bubbles blown through water and a butanol and glycerine solution filled to a certain depth in a glass cylinder 9.6 cm. in diameter and 47 cm. in length was measured.

The initial vertical velocity of drops was estimated from the experimental results, with reference to its trajectory.
Maximum stable droplets in dispersoids
Authors: Mugele R. A.
Published: June 2004

Maximum stable droplet size in nonuniform dispersoids may be ignored or treated as a statistical‐limiting parameter or as a physically significant quantity. In this paper the author shows that treatment as a physically significant quantity is always permissible and in most cases advantageous. It is found that maximum stable droplet size as well as a mean droplet size can be calculated in some cases from theory and in other cases from correlated experimental data; this is illustrated with examples involving sprays and emulsions.
The application of boundary‐layer theory to power‐law pseudoplastic fluids: Similar solutions
Authors: Schowalter W. R.
Published: June 2004

Two‐ and three‐dimensional boundary‐layer equations have been developed for pseudoplastic non‐Newtonian fluids which can be characterized by a power‐law relationship between shear stress and velocity gradient. The types of potential flows necessary for similar solutions to the boundary‐layer equations have been determined. For two‐dimensional flow the results are similar to those obtained for Newtonian fluids. For three‐dimensional flow, however, the possibility of similar solutions depends on the nature of the expression which describes effective viscosity of the fluid. At most, similar solutions are possible only for the case of flow past a flat plate where the potential velocity vector is not perpendicular to the leading edge of the plate; this is a much more restrictive condition than is obtained for Newtonian fluids.
The effect of dynamic surface tension on nucleate boiling coefficients
Authors: Jontz P. D. , Myers J. E.
Published: June 2004

A study was made of the effects the surface tension of aqueous solutions of surface‐active agents had on the bubble‐formation characteristics of these solutions. Bubbles were formed by two processes: by passing air through a horizontal orifice submerged in the solution and by nucleate boiling at an electrically heated surface. The experimental measurements taken with the air‐bubble system were used to determine the nature of the surface‐tension effect on air‐bubble formation. This knowledge was then applied to the interpretation of boiling measurements made with the same solutions. The boiling coefficients of the Tergitol‐water solution were found to vary inversely with dynamic surface tension. Boiling coefficients for Aerosol‐water solutions, however, varied in a manner which could not be related to surface‐tension effects.
The effects of superheat and surface roughness on boiling coefficients
Authors: Kurihara H. M. , Myers J. E.
Published: June 2004

The effects of liquid superheat and surface roughness on boiling coefficients were investigated in a series of experiments in which water, acetone,n‐hexane, carbon tetrachloride, and carbon disulfide were boiled on a flat plate. In addition to the usual thermal measurements, the number of active boiling centers was determined, whenever possible, by visual means, and a quantitative measure of surface roughness was made. It was found that the number of active boiling centers on the plate increased with increasing surface roughness and that the calculated boiling coefficients were proportional to the one‐third power of the number of bubble columns rising from the heated surface.

An equation has been derived relating boiling coefficients to fluid properties and the number of active boiling centers on a surface. A second equation, based on the theory of thermal fluctuations, has been proposed to relate the number of active boiling centers to the independent variables of surface‐roughness and temperature‐difference driving force. The limited data available have been found to follow this proposed relation.

The results of this work suggest a quantitative method of relating the boiling coefficient to the character of the surface which may explain the discrepancies observed in the slopes of boiling curves reported in the literature and in the actual values reported for the boiling coefficients measured on different surfaces.
Density fluctuations in fluidized beds
Authors: Baumgarten P. K. , Pigford R. L.
Published: June 2004

The effectiveness of fluidized beds is limited by the presence of density fluctuations such as those caused by gas bubbles. The size and frequency of such bubbles were measured in airfluidized beds of glass beads and silica‐alumina catalyst with a gamma‐ray absorption technique used.

The results showed that the gas bubbles developed owing to an influx of gas from the continuous dense phase. With increasing elevation in the bed the volumetric rate of bubble flow approached as a limit the total air flow minus the flow through the dense phase corresponding to minimum fluidization. The growth rate of bubble diameter was as much as 0.17 in./in. of elevation. Fluidization was most uniform with the cracking catalyst, for which the apparent density of the dense phase decreased with increasing gas velocity.
Compressions of liquids. I. Apparatus and method of measurement
Authors: Doolittle Arthur K. , Simon Ivan , Cornish Raymond M.
Published: June 2004

A novel type of piezometer used to measure the compressions of liquids from 20° to 300°C. and from 1 to 4,000 kg./sq. cm. is described. The accuracy anticipated is 4 parts in 10,000.
On the separation of gas mixtures in a jet
Authors: Gose Earl E.
Published: June 2004

In 1954 Becker found that the components of a gas mixture could be separated by allowing a jet of the gas mixture to expand in a low‐pressure chamber. The heavier molecules would concentrate near the center of the jet and the lighter ones near the edge. Thus the jet could be split into two streams, one containing more of the heavy component and one containing more of the light component. In this paper it will be shown that this effect can be predicted from the kinetic theory of gases and that the predicted magnitude of the effect agrees favorably with the experimental data of Becker.
Elutriation of solid particles from a dense‐phase fluidized bed
Authors: Wen Chin Yung , Hashinger Richard F.
Published: June 2004

The elutriation of fines from fluidized beds of two‐ and multiparticle systems is investigated. Materials used are glass beads and coal powder with air and helium as the elutriating gases.

A specific elutriation rate constant which takes into consideration the particle stratification and thus is nearly independent of the bed dimensions is employed in the correlation of the elutriation of fines.

The proposed generalized correlation applicable to a system of two particle sizes and to more complex ones is presented. Recorrelation of pertinent literature data by the dimensionless equation indicates good agreement in spite of a diversity of bed geometries. The effect of fluidized‐bed parameters on the rate of elutriation is examined, and applications and limitations of the correlation are shown.
Use of momentum balance in calibrating orifices for flow of gases
Authors: Martin J. J. , Pabbi V. R.
Published: June 2004

A method of determining the absolute calibration of a gas‐flow orifice without the use of gas holders or any comparative device is described. The method is based on the application of the momentum balance, as well as the energy balance, to the flow of the gas. The application requires the measurement of pressures on the face of the orifice in addition to the usual pressure‐drop measurements along the axis of flow.

Orifice coefficients determined by the force‐momentum principle are shown to agree within an average deviation of 1.4% with those determined by other standard techniques. Also the application of the force‐momentum principle demonstrates clearly why orifice coefficients are much less than unity.
Suspension of slurries by mechanical mixers
Authors: Weisman Joel , Efferding L. E.
Published: June 2004

The production of essentialy homogeneous sluries involves both initial solids suspension and expension of the particle bed to fill the container. When geometry and solids concentration are held constant, both phenomena are found to be controlled by similar dimensionless groupings of power per unit volume, density, and relative velocity between the fluid and particle. The dimensionless group applicable to bed expansion is shown to be consistent with hydro‐dynamic theory. Design equations for use with the paddle type of impeller are presented.
Filter cake washing performance
Authors: Kuo M. T.
Published: June 2004

Differential equations for a filter cake wash cycle are derived on the assumption that the wash liquor executes plug flow in the pores of the cake, with continuous mass transfer between the liquor and a boundary film of filtrate. These equations are solved and the solutions presented as performance charts. The solutions are compared with certain experimental results.
A theoretical analysis of laminar natural convection heat transfer to non‐Newtonian fluids
Authors: Acrivos Andreas
Published: June 2004

An equation is given for the local Nusselt number in laminar convection heat transfer to power‐law non‐Newtonian fluids. This expression, which even for Newtonian fluids (n = 1) does not appear to have been derived before, is obtained from the exact asymptotic solution of the appropriate laminar boundary layer equations and is applicable to any two‐dimensional surface or a surface of revolution about an axis of symmetry when, as is usually the case, Npr > 10.
Pressure drop and power requirements in a stirred fluidized bed
Authors: Leva Max
Published: June 2004

The paper reports fundamental observations on the effect which stirring of fluidized solids has on the pressure drop. Typical power requirements are also given.

The experimental pilot unit was of 6‐in. diameter and 12 in. high. A special blade or paddle type of stirrer had been built which permitted the evaluation of the effects of blade positioning, blade spacing relative to sense of rotation, as well as the effect of stirrer immersion and rotational speed.

The observations disclosed that blade positioning relative to sense of rotation had a very profound effect on pressure drop as well as on power requirements. When the solids circulation pattern as normally induced by the stirrer was of the same general character as that ordinarily encountered in a dense phase fluidized charge, the resulting pressure drop was always considerably lower than the conventional unstirred fluidized bed pressure drop. Furthermore for this type of stirrer the power requirements were also lowest. For other stirrer designs and other induced solids convection patterns the pressure drop was less influenced and the power requirements were much greater.

The solids used for the study were a relatively coarse silica sand for which both pressure drop as well as power requirement data were reported. Power requirement data were also obtained for a much finer alumina powder. When one emphasized the effect which particle properties, especially surface characteristics may have the level of the power data was much lower, although the data were of the same character as the characteristic values pertaining to the sand.