Hydrodynamic method for cleaning inner surfaces of pipes

A new method for cleaning inner surfaces of pipes was studied both theoretically and experimentally. The method is based on the phenomenon of a sphere rotating in a pipe (levitation), when the translational movement of the sphere is restricted and the sphere is subjected to fluid flow in the pipe. The high rotation velocity causes a vibration process, which may be exploited for cleaning sediments or rust from the inner surfaces of pipes. A simplified theoretical model for the determination of the relationships among the dimensionless parameters governing the rotation phenomenon was developed. The model was validated with experimental data and found to be appropriate for engineering design of the system. Application of the cleaning method was demonstrated by cleaning the sediments and rust off the inner surface of a one-inch nominal diameter pipe.     

A constitutive description for aluminum-0.1 pct magnesium alloy under hot working conditions

The constitutive behavior of an aluminum 0.1 wt pct Mg alloy deformed in the temperature range of 573 to 823 K at strain rates between 0.001 and 100 s⁻¹ is analyzed on the basis of the concept of the mechanical threshold stress (MTS), , taking into consideration the contributions from the different strengthening mechanisms that could be present in this alloy, , which include one component that arises from the interaction between dislocations and solute atoms, , and another contribution from the interaction between mobile and forest dislocations, . The evolution of is described in terms of a generalized form of an exponential-saturation equation, whereas the characterization of the ratio, s _i ( , T), between the flow stress at any strain rate and temperature, and the two components is carried out by means of the phenomenological model advanced by Kocks and co-workers. It is shown that the experimental values of the flow stress as well as the work-hardening rate can be accurately described following this approach and that the maximum difference between the experimental and calculated values of such a parameter is less than ±4 MPa. The analysis conducted from continuous stress-strain curves determined at constant temperature and strain rate indicates that the relaxation strain in the generalized form of the Sah et al. relationship displays a significant strain rate dependence. The inclusion of such a dependence into the analysis by means of a simple parametric relationship leads to an improvement in the accuracy of the prediction of the model.     

Effective water diffusivity in deep-fat fried restructured potato product

Water diffusivity was determined for a restructured potato product undergoing deep-fat frying. Pre-fried product gel-strength, expressed by its deformability modulus, varied from 37 to 127 kPa and markedly affected the effective diffusion coefficients, ranging from 3.31 to 1.58 × 10⁻⁹ m² s⁻¹, respectively. Pre- and post-fried effective water diffusivity decreased with higher deformability modulus. Frying time reduced the effective water diffusivity only when the initial deformability modulus was higher than 52 and 79 kPa for 1 and 5 min, respectively. Oil uptake criterion was found to increase with the effective water diffusivity for frying durations of 1 and 5 min.     

An improvement of Davies’ attack on DES

In this paper we improve Davies’ attack [2] on DES to become capable of breaking the full 16-round DES faster than the exhaustive search. Our attack requires 2⁵⁰ known plaintexts and 2⁵⁰ complexity of analysis. If independent subkeys are used, a variant of this attack can find 26 bits out of the 768 key bits using 2⁵² known plaintexts. All the 768 bits of the subkeys can be found using 2⁶⁰ known plaintexts. The data analysis requires only several minutes on a SPARC workstation. Therefore, this is the third successful attack on DES, faster than brute force, after differential cryptanalysis [1] and linear cryptanalysis [5]. We also suggest criteria which make the S-boxes immune to this attack.     

The Influence of Tablet Shape and Pan Speed on Intra-tablet Film Coating Uniformity

Four different tablet shapes (round, oval, capsule, and large oval) were coated in a small-scale coating pan at three different pan rotational speeds. The coating film thickness was measured on the top face, the edge of the land, and the belly band of each tablet shape. The results showed that tablet shape directly influences intra-tablet coating uniformity (uniformity decreasing from round, oval, capsule, to large oval). In almost all cases, coating uniformity increased with pan speed.     

Antecedents of dental anxiety: learned responses versus personality traits

Patients recovering from alcohol and other drug addiction have unique medical and pharmacological needs. Careful selection of medications call decrease the risk of relapse. Angiotensin-converting enzyme inhibitors and calcium channel-blocking medications are excellent choices to treat hypertension. Most gastrointestinal problems resolve with abstinence and can be treated nonpharmacologically. In managing pain, physicians should avoid narcotics and use nonpharmacological treatment whenever possible. Treating recovering patients with HIV can be challenging because of the side effects of many of the antiviral medications. The newer antiviral agents have fewer side effects and contraindications. Commonly used remedies for colds and cough can cause a relapse to drug use. Patients with diabetes mellitus need to be monitored very closely in early recovery to prevent hypoglycemia. Frequently a team approach is helpful in managing the medication needs of patients in recovery.     

Prediction of rates of heat or mass transfer in complex situations by interpolating between simpler limiting cases

This paper emphasizes the generality of a simple algebraic procedure suggested in 1962 by the author to predict the rate of heat or mass transfer in complex situations. It consists in replacing the terms in the convective diffusion equation by expressions involving scaling quantities multiplied by constants. Thus the convective-diffusion equation is replaced by an algebraic equation for the mass transfer coefficient containing a number of constants. The constants are determined from the solutions available for some simpler limiting cases. To illustrate the procedure a variety of examples are given which include: penetration theory for diffusion with chemical reaction, laminar flow along a plate accompanied by a chemical reaction, diffusion with chemical reaction in a turbulent liquid, mass transfer from a drop to a continuous phase, unsteady heat transfer to a liquid in steady laminar flow along a plate and free convection superimposed on forced convection. Numerous other complex situations have been or can be treated by interpolation between some simpler limiting cases.     

The effects of stimulus frequency on subsequent recall of backward associates.

Previous research has shown that increased Thorndike-Lorge frequency (F) of stimulus-terms leads to poorer paired-associate learning (PAL), while increased F-level of response-terms facilitates PAL. Therefore, if a word pair is learned in the order A-B, then later tested in reverse (B-A), there are two possibilities. (1) Error level could be the same on the reverse test, implying that performance on the A-B learning trials determined the strength of the B-A association. (2) Error level on the reverse test could revert to what it would have been if the B-A pair had been learned originally. In the present study the experimental group learned A-B word pairs and was tested on corresponding B-A versions. Results showed that, for the experimental group, the relationship between errors and F-level of the A-terms shifted dramatically between the last A-B trial and B-A test trial. On the B-A test trial, this group performed in a manner comparable to that of a control group trained on B-A throughout. Thus, for pairs which differed in F-level of their stimulus-terms, relative performance during the A-B learning trials was not a crucial factor in later B-A performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimal Scheduling of Nitrogen Fertilization and Irrigation

This paper develops and applies a mathematical model for determining the economically optimal scheduling of fertilization and irrigation (fertigation) that maximizes the farmer's profits. The analysis assumes a single crop (corn) and a single growing season. For a given total seasonal fertigation level, the optimal scheduling solution to the optimization problem identifies not only the maximum profits but also the minimum total nitrogen leached below the root zone and, therefore, the minimum groundwater contamination. The conceptual framework, coupled with the experimental data for corn, are used to investigate the impacts of taxing the total nitrogen leaching and an action equivalent taxation of nitrogen fertilizer. It is demonstrated that the increase in the fertilizer tax required to achieve a given level of reduction of total nitrogen leaching is much smaller in relation to the change in the tax on leached nitrogen required to achieve the same reduction.     

UHF double dielectric resonator filter with linearised tuning range

A UHF double dielectric resonator filter operating in the TE_01δ mode has been constructed with a high Q, wide (14%) and reasonably linear tuning range. This has been achieved by varying the gap between the resonators, and using the influence of the end wall on the movable resonator. The experimental device is readily scaleable to the cellular radio wave bands