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A technique is derived providing for the analysis of busy period processes in the queueing models M/Mn /1 and Mn /M/1; queueing models with state dependent service and arrival rates respectively. A single treatment covers both models and no separate analysis is required.

Twenty commercially available oxygen meters using improved epeated calibration by the vanadium equilibration method showed the slope of the curve to be constant and identical for all meters. One vanadium equilibration per month was sufficient to correct for drift of the intercept. Ten meters (at one site) were used continuously for 18 months without failure. Two oxygen meters are now in routine use in EBR-II primary sodium. The observed stability and life of the present meters are considered adequate for effective use in LMFBR sodium systems. 13 references. (auth)

A system has been developed to measure continuously the 235U and 234U enrichment in the UF6 product of a gaseous diffusion plant. The measurements are made on liquid UF6 prior to withdrawal into product cylinders. The 235U enrichment is measured to a relative accuracy of 0.5% at two sigma by counting the 185.7-keV gamma ray from 235U with an NaI detector. The 234U enrichment is measured with a neutron detector counting (α,n) neutrons from UF6. The neutron system can measure either 234 U enrichment directly or 235 U enrichment indirectly (for low-enriched uranium, 2 to 5% 235U, the two enrichments are nearly proportional). The accuracy of the neutron measurement is 2.5% at two sigma. The gamma and neutron measurements are independent and could be used singly if only one isotope were desired. Both are required to measure 235 U and 234 U enrichment. The system is presently installed at the Goodyear Atomic Corporation gaseous diffusion plant in Piketon, Ohio.

Dispersion-strengthened ferritic steels are being studied for possible use as canning material for sodium-cooled fast reactors. The basic alloy chosen contains nominally Fe—13% Cr—1.5% Mo— 3.5% Ti ...

From joint meeting of the American Nuclear Societty and the Atomic Industrial Forum and Nuclear Energy Exhibition; San Francisco, California, USA (11 Nov 1973). Materials engineering problems are discussed for the following areas: superconducting magnets, tritium breeding, structural materials, radiation damage, electrical insulating materials, tritium problems, hydrogen diffusion barrier, remote fabrication, thermal insulation, and magnet shield. (MOW)

The oxygen concentration of sodium in equilibrium with uranium-25% plutonium oxide fuel was measured at temperatures of 650 to 900 deg C for fuels with oxygen-to-metal ratios of 1.90, 1.94, and 1.97. The oxygen concentration in sodium at the three-phase Na -- MO/sub 2-x/ Na/sub 3/MO/sub 4/ (M = uranium plus plutonium) equilibrium has also been measured for the same temperature range. This three-phase equilibrium was established by reacting mixed-oxide fuel with sodium to which Na/sub 2/O had been added. The oxygen concentrations in sodium were determined by the vanadium-wire equilibration method. The oxygen concentration in sodium at the three-phase equilibrium varied from ~ 0.1 to 0.4 ppM in the temperature range investigated. Oxygen concentrations in EBR-II primary sodium, which have been measured by the same method, vary from 0.4 to 0.9 ppM oxygen depending on the cold-trap operation. These values indicate that the sodium--fuel reaction product, i.e., Na/sub 3/MO/sub 4/, is stable in sodium at the temperatures (

Recent data and published data on the de-carburization kinetics of Cr–1% Mo steel in sodium from 800 to 1300°F were correlated by expressing changes in bulk carbon content of samples of different t...

A class of nonmaximally flat monotonic low-pass filters with sharp cutoff are discussed and shown to provide better magnitude response both in the passband and in the stopband than their maximally flat counterparts. The normalized pole and zero locations of these filters are tabulated for n = 3-11 and different values of the minimum stopband attenuation.

An experimental characterization of the effects of thermal treatments and of fast-neutron irradiation on the elevated-temperature tensile and creep-rupture properties of a gas tungsten-arc-deposite...

Les alliages GaxIn1-xP sont étudiés à 300 K par électroréflexion. La variation parabolique de E0 et E1 avec x est précisée, les paramètres de courbure étant respectivement 0,49 eV et 0,86 eV. On étudie la variation de E0 en fonction de la température entre 8 K et 300 K par piézoréflexion. On trouve une variation linéaire entre 100 et 300 K. Le coefficient de température est (— 4,4 ± 0,4) eV/K. Aux incertitudes près, il est le même quel que soit x. A basse température, le paramètre de courbure de E0(x) vaut 0,42 eV. La bande interdite indirecte Xc6 — Ɖv8 est obtenue dans la même gamme de température par électrotransmission. Les paramètres du point de croisement des minima Ɖ-X de la bande de conduction sont pour T inférieur à 10 K, xc = 0,69 ± 0,015, Ee = 2,33 ± 0,01 eV. A T = 300 K les valeurs xc = 0,63 ± 0,015, Ee = 2,14 ± 0,01 eV sont confirmées. L'interprétation des spectres de luminescence dans le cas des dopages N et S est discutée. En particulier l'accroissement résonnant de la transition due à N se produit pour x = 0,65 et non 0,71.

Multifilamentary composite wires of Nb Ti and Nb3Sn have been irradiated at 60 ± 5°C with fast neutrons to fluences of 6 × 1019 n/cm2. Measurements of the superconducting critical current, Ic, as a...

Few technical writers and editors understand the roles and importance of conjunctions. In fact, many find it hard to distinguish between otherwise and alternatively, between while and whereas, and between however and hence—imprecisions that too often lead to unclear writing or even technical inaccuracies. This paper uses a practical linguistic approach to describe word types that couple sentence patterns: those that subordinate a clause to the main part of a sentence pattern; those that conjoin clauses, phrases, or words; and those that connect clauses together. A “Table of Couplers” groups the main conjunctions into sub-sets according to meaning, thus allowing comparison and easy selection of the most appropriate word.

An expansion is derived for the solution to the transport equation in two dimensions subject to boundary conditions given for an arbitrary convex region. Questions of high-energy transport are considered along with the properties of the dose response function. The expansion of the solution of the transport equation is presented in terms of a parameter which measures the lateral dispersion of an unidirectional beam. This parameter is usually small and the expansion is expected to converge rapidly. The dominant term in the expansion is related to fluence-to-dose conversion factors in a semiinfinite slab for normal incidence. A convenient parameterization of the conversion factors is provided along with numerical examples.

If the service time of a customer depends on the length of time he has waited in the queue then it is shown that queue discipline has a significant effect on the maximum arrival rate for which the ...

SummaryPores originate from precursors in the substrate surface and gradually close as plating proceeds, forming parabolic pore walls. The range of precursor sizes, and their density, is a function of substrate history before entering the bath. The rate of sealing for a given precursor area is a function of plating conditions. The size distribution of precursors has been studied (by means of pore numbers derived from conductance measurements on gold coatings) for some copper-based substrates. Among metallurgy similar OFHC copper rods the numbers of precursors varied two hundredfold; the pore-free thickness varied by a factor of ten. There was a higher surface density of precursors in one rod sample than in underlying layers exposed by chemical polishing. Age-hardened Be-Cu sheet had a higher density of small precursors than had OFHC copper or phosphor-bronze sheets. In contrast to the copper rod, bright dipping exposed underlying Be-Cu with a higher precursor density, probably a sub-scale. OFHC copper and...

CORNMOD is a comprehensive mathematical model that not only simulates energy and gas ex change at the plant-air interface but also predicts the consequences of decisions (e.g., when to plant, when to irrigate). An extensive search of the litera ture revealed many models that antedate CORN MOD, and many of them were adequate for biological applications. However, the search also revealed many inadequacies in our understanding of the environment within the plant canopy. CORNMOD is a simulator of agricultural crop- production systems and it forms a basic framework for a model that will eventually be able to analyze more complex agricultural systems. At present the model is still being developed, and much work remains to be done.

The 14-MeV neutrons from a controlled DT fusion plasma can potentially be used to produce neutron source multiplication and energy multiplication through fission in a heavy-element blanket surround...

Fatigue crack growth rates of Types 316 and 321 stainless steel were studied as a function of stress intensity, temperature, relative humidity, and gas environment. At 25°C it was shown tha...

The current pace of development of laser-driven fusion together with the urgency of providing sources of safe, clean, low-cost electrical energy have prompted consideration of the major materials p...

The considerations involved in the evaluation of the suitability of any geological formations for the disposal of radioactive wastes are illustrated by summarizing some of the studies performed in ...

A computer program named ORRIBLE was written to predict the flow and temperature distribution for steady single-phase flow through a bundle of 19 heated rods spaced by helical wire wraps in a hexagonal duct. Any combination of flow subchannels can be blocked at the inlet. The section can have an unheated entrance length followed by a heated section and an unheated exit length. In the heated section, the linear heat rate of each of the rods can be individually specified. Turbulent interaction, sweeping crossflow due to the wire wrap, and transverse thermal conduction are considered. An approximate relationship for pressure-diversion crossflow in terms of local axial mass velocities is used to eliminate pressure as a variable. Hence, the computational procedure does not require iterative techniques.

Gas tagging consists of the addition to nuclear reactor fuel pins of small amounts of gas having a unique isotopic composition for each assembly; when an assembly fails during subsequent irradiatio...

Irradiation experiments carried out by the Comitato Nazionale Energia Nucleare to evaluate the thermal behavior of different types of fuel are described. The integral thermal conductivity has been ...

uring recent months my reflections on wilderness have been worked and reworked through participation in hearings concerning the disposition of areas and rivers in the Northwest which might still be conceived wild. Attending to the testimony of hundreds, and attempting to formulate my own, I have strained to discern both the actual significance wilderness may hold for us in manifold ways and, more deeply, to ponder anew the potential significance it might yet hold within the shaping of our destiny as a people. These hearings themselves have brought out a wracking incongruity of relatively recent origin: When Thoreau wrote "that in Wildness is the preservation of the World," he surely was not thinking of Wildness as being yarded and bounded in specified preserves. Yet more and more, of course, we have been forced to conceive wilderness lands under the rubric of conservation. The deliberateness of Thoreau's Westward Walking was not that of an excursion into an area set aside to remain in its natural state. The "West" he signified did not remain by man's decree, subject to regulations aimed at preserving it from human onslaught, or to quotas of scheduled access. "The unexplored forests and meadows" but for which he thought "our village life would stagnate" still sufficiently abounded matter-of-factly to obviate their holding tenure under the aegis of planning and deliberate disposition. Thus the re-creative tonic of wildness was not about to be bottled and labeled as a recreational resource. And matter-of-factness in the style of human venturing amidst wild places was not yet massively invaded by self-conscious searching for "the wilderness experience," even though eulogies of natural beauty and sublimity were popular among the cultivated. Most widely, in Thoreau's time, the appeal was to venturesomeness, to setting out anew, to a break with conventions in which life might have been constrained if not falsified, to exploration and discovery rich in promise of new beginnings and firmer foundations, to a testing of mettle in which a man might find himself and inherit a dignity proper to him. Wilderness offered invitation and opportunity for active undertaking on which the person might thrive and even communities might be founded. Its call was that of a rallying of men to enterprise, to work that might

This paper describes a mathematical model of part of the life-cycle of Haemonchus contortus, a parasitic worm of sheep and other ruminants. The model simulates the free- living stages of the life-cycle, beginning with eggs passing out in the faeces of the sheep, and predicts the con centration of infective larvae on the pasture that will develop from these eggs according to the prevailing climatic conditions. The output from the model has been compared over a three-year period with data from a real experiment; the agreement is good enough to indicate that the model is basically sound. The authors intend to combine this model with a model of the epidemiological and physiological responses of sheep to various levels of contamination of their forage by infective larvae of H. contortus. Such a model is expected to be useful in devising management strategies to control this parasite.

The 60-square-mile region of extreme northwest Indiana, which includes the cities of Gary and East Chicago, is a highly urbanized and industrialized area. Pollution data over the region show high levels of cadmium, a toxic metal. There are several hundred sources of cadmium in the area, and the impact of each type of source is unclear. An accurate representation of the flow of cadmium would make it possible to structure a reasonable and efficient policy for controlling cadmium pollution. This paper describes a GASP IV computer model for that flow. The basic model is an aggregate continuous model which displays the time behavior of cadmium levels in each of nineteen compartments over a two-year period. This aggregate model raises several ques tions regarding the effects of discrete events such as rainfall. Since the GASP IV language is capable of combined continuous-discrete simulation, these new factors are easily incorporated into the model. Results of the simulation show the relative impact of the various types of sources and provide some insight into control policies. A continuous model was first constructed. Then modifications based on real-world data were implemented as discrete events. The successive forms of the model proved useful for studying at least two of the characteristics of cadmium flow in an urban ecosystem.

SummaryActivation of ABS plastic prior to electroless deposition is often achieved by treatment with mixed SnCl2/PdCl2 catalysts in conjunction with various accelerator solutions. The mechanism of acceleration for NH4HF2, H2SO4, NH4, OH and NaOH accelerators was investigated using electron microscopy and electron diffraction analysis of the adsorbed species. The action of all four accelerators was to convert adsorbed catalyst present as hydrolysed stannous and palladous chlorides to active metallic palladium. The catalytic activity of the ABS surface is directly related to the number of catalytic palladium nuclei created. This number depends on the amount of SnCl2/PdCl2 catalyst adsorbed, the degree of acceleration and the type of accelerator employed.

SummaryA range of gold alloy electrodeposits wer produced from a variety of electrolyte systems for evaluations in the industrial market. Electrolytes ranged from acid to alkaline sulphite and cyanide gold systems in order to give a wide range for the evaluation. Each electrolyte system is discussed in detail with information on typical formulation and tables provided on physical characteristics of the deposits. Seven electrolytes, including two typical industrial formulations, were used for the evaluation and each deposit was investigated with regard to specifications relative to printed circuits, semi-conductors and general contacts. Microhardness, internal stress, wear resistance, corrosion resistance, density, solderability and heat treatment were all measured and the results tabulated. General conclusions suggest further evaluations of the Au-Cu-Cd system, provided a change in specifications is permitted.

This article, first of all, describes some of the results of research into the relationship between grammatical choice and rhetorical function in English for Science and Technology (EST). The second part of the paper presents some details about procedures used in EST courses for non-native speakers. We emphasize changes made in these procedures through application of the results of our research. Some unsolved problems are referred to.

The applicability of portable instruments for rapid nondestructive verification of the enrichment of UF6 in cylinders has been tested on a large number of Types-30 and -5A cylinders. Three basic te...

A monostable multivibrator using a complementary pair of transistors which needs no standing power is described. At the output terminals rectangular pulses having rise and fall times in the nanosecond range are obtained. The duration of output pulses is controlled by a diode clamp and can be made almost independent of the d.c. current gain of the transistors used. A modified version of the basic circuit with high loading capacity and enabling increased duty cycle operation is also presented.

This paper studies the effects of using correlated random-number streams in replications of a simula tion experiment in which output is to be related to input by linear or quadratic response surfaces. For the linear case, it is shown that either positively or negatively correlated streams produce a smaller generalized variance for the least-squares estimates than occur when the streams are independent. Al though the prediction variance is small with nega tively correlated streams, positively correlated streams produce a smaller variance for the estimated slope. In the quadratic case it is shown that of twenty- seven possible input correlation designs only six guarantee a smaller generalized variance. Only one of these produces a smaller prediction variance. However, no plan will guarantee a smaller slope variance. In the quadratic case one often wants the slope variance to be as small as possible since the objective of the study may be to determine where the maximum or minimum response occurs in terms of the input.

A computer model in FORTRAN for the growth of the giant kelp, Macrocystis, which inhabits the coastal waters of southern California, has been developed. The present model considers only physical factors, water temperature and submarine light, as the factors that control the growth of single fronds in large kelp beds. The model has been used to examine two aspects of kelp growth in water of 20 meters depth. The opti mum time of the year for the start of new growth of fronds arising from the bottom in an established kelp bed was found to be early June. The optimum time of the year for regrowth of harvested canopy was found to be early July. In each case, the optimum time is interpreted as providing the shortest time for the frond to reach "maturity" (a length of 40 meters). The penetration of sunlight into the hydrosphere is adversely affected by particulate matter in the water such as results from the introduction of sewage ef fluent. The simulation identifies the critical values for turbidity which will prevent new growth from occurring. At a depth of 20 meters, light absorbency of 18% per meter reduces the possible growing time by only 20%. But when absorbency is increased to only 24%, the growing time becomes zero. Simulation runs for other kelp-bed water depths revealed similar critical values of absorbency resulting in the restric tion of growth to shallower waters. This type of analysis to resource-management efforts is obvious. The paper concludes with suggestions for modifying the integration techniques used and for incorporating additional quantifiable values to refine the model.

SMOOTH is a packaged network simulation language written in FORTRAN. It is based on the GASP TV and GERT IIIZ simulation languages and is capable of representing and analyzing models which include both continuous variables and discrete events. As a net work language, SMOOTH consists of a set of graphical symbols, users' input instructions, and a computer program. The basic symbols are nodes and branches: nodes perform specified functions on system varia bzes, while branches indicate precedence or function aZ relations between nodes. In using SMOOTH, the user models the system he wishes to study as a pair of interrelated networks and then describes the net works to the computer by means of the SMOOTH lan guage's input instructions. The SMOOTH computer pro gram analyzes the netzoork using simulation. No com puter programming or sophisticated mathematical tech nique is required on the part of the user. This paper discusses the concepts and symbols of SMOOTH and includes as an example a SMOOTH model of a lake ecosystem. SMOOTH has been used to study biological systems, environmental pollution by trace metals and insecticides, and problems in systems dy namics. It is the first network simulation language capable of analyzing models of a combined continuous discrete nature.

Experiments were performed with a 19-rod test assembly in the fuel failure mockup sodium loop in which fuel rods were simulated by electrical cartridge heaters having the same external configuratio...

Recent transmission electron microscopy examinations of heavy-ion- bombarded vanadium have shown that the peak swelling temperature was sensitive to impurity content. In addition, anomalously large strain fields were observed around voids at 650 deg C. At higher temperatures, thin precipitates were observed to form on void surfaces. These strain and precipitate effects are shown to be caused by impurity segregation to void surfaces during irradiation. (auth)

PETER W. HOUSE has, since November of 1971, been with the U.S. Environmental Protection Agency where he is assistant director of the Washington Environ mental Research Center in the office of Research and Development. He is the former president of Envirometrics, Inc. During his four and one-half years at the Washington Center for Metropolitan Studies and Envirometrics (April 1967-October 1971) he directed the development of three urban operation al simulation models, including the CITY models and the RIVER BASIN MODEL. Dr. House received his master's degree in economics from Clark University and thereafter went to work for the U.S. Department of Agriculture as a research economist in the Economic Research Service (ERS). During his tenure at ERS (February 1960-March 1967) he performed a number of studies concerning suburban/ farmland and preferential tax assessment, and was selected to attend Cornell University to complete work on his doctorate. Currently, at EPA, Dr. House and his staff conduct studies and develop forecasts which can move EPA to a position of being able not only to enhance the environment but also to provide for long-term preven tion of pollutants. He is project leader of the team responsible for development of the Strategic Environmental Assessment System (SEAS). Two books under his authorship have recently been published: The Urban Environmental System: Modeling for Research, Policy-Making and Education, published by Sage Publications: and, with Edward R. Williams, The State of the System (SOS) Model, published by EPA.