bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some queuing problems in machine maintenanc
Authors: Stoller David S. 
Published: May 2007

AbstractThis paper discusses some queuing problems that arise in the context of the maintenance of a group of machines, each of which is operated intermittently and all of which are subject to several kinds of malfunctions. A general formulation of this problem is made and the general method of solution indicated. A class of solutions in form suitable for direct computations is given. As a special case, a solution is given to the case of mjrepairmen of type j, j = 1, …, k for a group of fully utilized machined.
Some principles for a data‐processing system in logistics
Authors: Geisler M. A. 
Published: May 2007

AbstractSome of the principles and concepts of a revised logistics data‐processing system, proposed for the Air Force and developed at RAND, are discussed. These ideas provide a general framework in which a data‐processing system might be developed that would be able to meet the operational needs of the 1960's. The ideas developed in this paper, although pointed particularly at the Air Force, might have relevance and use for the other military services and for industry in general.
The allocation of development funds: An analytic approach
Authors: Daubin Scott C. 
Published: May 2007

AbstractThe administrative problem of fund allocation among the several projects constituting the development program is considered from an analytic‐economic viewpoint. The concept of operational potential is introduced and used in establishing a measure of effectiveness for the development program, the “development contribution function.” The problem then resolves to the maximization of a mathematical expression. An example is worked out to demonstrate the method and the utility of the results, Certain characteristics of the solution which are of general applicability are discussed. The functional relationships among the groups concerned with development is considered; the contribution of each groupis definedin the form of equation parameters, The importance of well designed development administrative machinery, particularly relating to the integration of the operational and the technical elements, becomes immediately apparent.
Characteristics of usage of supply items aboard naval ships and the significance to supply management
Authors: Garrett John Henry 
Published: May 2007

AbstractEDITOR'S NOTE: This paper presents naval problems in supply of materiel. Research is being conducted at the George Washington University Logistics Research Project in connection with effecting the highest degree of self‐sufficiency of fleets at sea. The Bureau of Supplies and Accounts and the George Washington University Logistics Research Project are jointly conducting a research program known as “The Allowance List Test Program.” One of the notable features of this program is that military worth (essentiality) measurements for repair parts are being introduced explicitly.
Linear model for evaluating complex systems
Authors: Thrall R. M. , Coombs C. H. , Caldwell W. 
Published: May 2007

AbstractThe first phases of a long‐range project for developing models for the evaluation of intelligence systems in terms of measurable outputs are reported. In making such evaluations, the number of correct identifications, number of false alarms, number of displacements, and number of complete misses must be measured, in each of several categories (such as infantry, artillery, armor, supply lines), in each of a number of sectors (front line, rear, far rear), and in each of several situations (such as attack or defense, good or poor mobility). The major results to date are (1) the development of experimental techniques, (2) the formulation of an analytical model. (3) the development of analysis techniques for evaluation of parameters in the model in terms of empirical results, (4) the preliminary evaluation of parameters (rank‐order correlations of 0.8 and higher have been established between some of the analytic predictions and the empirical results), and (5) formulation of several concrete unsolved problems out of the over‐all problem. Plans for continued studv are discussed.
Further notes on the loss resulting from the use of incorrect data in computing an optimal inventory policy
Authors: Levy Joel 
Published: May 2007

AbstractIn the Naval Research Logistics Quarterly of March 1958, the author published some exploratory research on ‚Loss Resulting from the Use of Incorrect Data in Computing an Optimal Inventory Policy.”︁ The present paper continues these investigations by examining the effect of errors in the loss function (Part I) and in the discount rate (Part II).
Note on solving linear programs in integers
Authors: Dantzig G. B. 
Published: May 2007

AbstractA recent result of Gomory (Princeton) solved an outstanding problem, namely that of solving linear programs in integers. Gomory showed how to add linear inequality constraints to a linear programming problem automatically in such a way that the extreme points of the resulting convex contain only integral solutions in the neighborhood of the minimum. In this paper an alternative method is given for generating these additional constraints in a way easy to justify and to apply. However it is not known whether these conditions will lead to a solution in a finite number of iterations of the simplex method as is true for the stronger Gomory conditions. Thus anyone considering their practical use should weigh the ease of generation against the extra number of iterations that will undoubtedly be required for convergence.
A difficulty in linear programming for transportation problems
Authors: Luther Marvin , Walsh John E. 
Published: May 2007

AbstractLinear programming has many worthwhile applications to transportation problems of a relatively uncomplicated nature. For inore complicated problems, however, a realistic linear‐programming formulation can require such an excessive number of variables that obtaining a solution is not feasible. This paper shows that an excessive number of variables is usually required when different types of items are to be transported subject to time restrictions and on carriers that can simultaneously handle several items.
The feasibility of a global airlift
Authors: Weinberg R. S. , Higgins J. W. 
Published: May 2007

AbstractNote by Managing Editor: The impossibility of a global airlift can be established by very simple means intuitively. However, the methods used by the authors in arriving at this same conclusion, even by a limited analysis, may be of interest to the reader. This paper gives quantitative proof of the magnitude of effort required for importing by air in lieu of using sea lift.
Maximum number of iterations in the transportation problem
Authors: Simonnard Michel A. , Hadley G. F. 
Published: May 2007

AbstractIt is shown that there are precisely nm‐1mn−1 bases in a transportation problem having m destinations and n origins. This number gives an upper limit to the number of iterations in solving the problem and is much smaller than that given by the combinatorial formula (mn)!/(m+n−1)1 (mn+1−m−n)1.
Renewal‐theoretic analysis of a two‐bin inventory control policy
Authors: Gaver D. P. 
Published: May 2007

AbstractRenewal theory is used to derive the stationary distribution of inventory present at a stocking point characterized by stationary compound Poisson demand, independent and generally distributed lead times, impatient customers, and the use of a two‐bin ordering rule. Inventory‐associated costs are evaluated, and a numerical example is given.
The new military standard for inspection by variables
Authors: Rosenblatt Harry M. , Wolman William 
Published: May 2007

AbstractThe Standard described here was prepared to meet a growing need for the use of standard sampling plans for inspecting products procured by the Government. It may serve as an alternate to MIL‐STD‐105A, which provides sampling plans for lot‐acceptance inspection by attributes. The variables sampling plans apply to a single quality characteristic and maybe used whenever the quality characteristic for test can be measured on a continuous scale. Like the pattern of MIL‐STD‐105A, risks of rejecting acceptable material were planned to decrease with increase in size and lot. In the new Standard, however, samples sizes are considerably smaller than those in MIL‐STD‐105A for corresponding sampling plansThe Standard outlines procedures to be followed when the variability is unknown—either a standard‐deviation or an average‐range method—as well as those to be used when the variability is known. A new concept in the Standard is a lot‐acceptance criterion obtained by comparing an unbiased minimum‐variance estimate, r, of the true percent defective with a suitably chosen constant, M, which represents the maximum allowable percent defective for sample estimates. This procedure, when used for the two‐sided specification‐limit case, provides operating characteristics, for given percent defective, which are essentially the same as those for the one‐sided specification‐limit case, regardless of the total percent defective in the lot, which consists of the sum of the percent defective above the upper and below the lower specification limits. For the one‐sided specification‐limit case, the acceptance criterion provides the identical probability of acceptance as obtained with the familiar ks statistic for suitably chosen k. Values of k also are included in the standard, thus, permitting use of either form of the acceptance criterion.
Method for first‐stage evaluation of complex man‐machine systems
Authors: Garfunkel I. M. , Walsh John E. 
Published: May 2007

AbstractPerformance assessment is a valuable tool for determining whether or not a system is behaving satisfactorily and for isolating trouble areas if the performance is unsatisfactory. This type of evaluation is especially useful for systems that are in their initial stages of operation. If a new system represents a large‐order combination of men and machines, development of a satisfactory method for evaluating such a system is not an easy task. Experimental simulation involving actual (or laboratory) operation appears to furnish a feasible and realistic basis for such evaluations, By use of this approach, a model has been developed that seems to be acceptable for most evaluation purposes. This model is of a somewhat elementary mathematical form, being a linear sum of the contributions for important subdivisions with respect to system components and time; however, the model is elaborate in the sense that many inputs rely heavily on experience ‐ judgment considerations. Explicitly, a measure of effectiveness is developed which is based on a comparison of what the system did with what it should have done, as determined by the recorded results of the simulation exercise. An assessment of a system' s over‐all behavior can be obtained by performing an evaluation for each of a representative set of the important types of situations for this system.
A first experiment in logistics system simulation
Authors: Geisler Murray A. 
Published: May 2007

AbstractThis paper essentially describes the activities of the RAND Logistics Systems Laboratory during its first year of operation. During this year, the laboratory conducted an important first experiment in which it tested a series of proposed changes to the Air Force supply system.The test involved the creation of two versions of an Air Force logistics system, one which simulated a 1956 Air Force logistics system and another which was modified to contain the proposed supply policies. These two systems were operated in parallel and were given the same support task to accomplish. The system which was able to accomplish its job at lesser cost was deemed the better system.The simulation was a composite of man‐machine models, in which the men were assigned management responsibilities and functions and the machines performed routine actions. The men were identified by titles which have counterparts in the real‐world logistics system. The two logistics systems were operated under compressed time so that each hour in the laboratory simulated a day's experience in the real world. This enabled the simulation to cover 3–1/2 years' experience and 2 simulated wars.The experiment indicated that, according to the criterion established, the logistics system containing the newer supply policies was a better system. The experiment also indicated ways in which revisions to the procedures by which the new policies are implemented would benefit their future use.The experiment indicated that this type of logistics system simulation did develop many more insights into the operation of proposed policies than traditional analytical techniques normally provide, and it did extend the traditional descriptions provided to real‐world organizations of such proposed policies. At the same time, the experiment did highlight the complexities of testing logistics policies, even under the idealized conditions of the laboratory, and the problems of interpreting experimental findings.
Web‐based international studies in limited populations of pediatric leukemia
Authors: Valsecchi Maria Grazia , Silvestri Daniela , Covezzoli Anna , De Lorenzo Paola 
Published: May 2007

AbstractBackgroundRecent progress in cancer research leads to the characterization of small subgroups of patients by genetic/biological features. Clinical studies in this setting are frequently promoted by international networks of independent researchers and are limited by practical and methodological constraints, not least the regulations recently issued by national and international institutions (EU Directive 2001/20/EC).ProcedureWe reviewed various methods in the design of international multicenter studies, with focus on randomized clinical trials.ResultsThis paper reports our experience in planning and conducting international studies in childhood leukemia. We applied a decentralized study conduct based on a two‐level structure, comprising a national and an international coordinating level. For the more recent trials this structure was implemented as a web‐based system. This approach accommodates major legal requirements (e.g., safety reporting) and ensures Good Clinical Practice principles by implementing risk‐oriented monitoring procedures.ConclusionsSetting up international non‐commercial trials is increasingly complicated. Still, they are strongly needed for answering relevant questions in limited populations. Pediatr Blood Cancer 2008;50:270–273. © 2007 Wiley‐Liss, Inc.
A DIGE analysis of developing poplar leaves subjected to ozone reveals major changes in carbon metabolism
Authors: Bohler Sacha , Bagard Matthieu , Oufir Mouhssin , Planchon Sébastien , Hoffmann Lucien , Jolivet Yves , Hausman Jean‐François , Dizengremel Pierre , Renaut Jenny 
Published: May 2007

AbstractTropospheric ozone pollution is described as having major negative effects on plants, compromising plant survival. Carbon metabolism is especially affected. In the present work, the effects of chronic ozone exposure were evaluated at the proteomic level in developing leaves of young poplar plants exposed to 120 ppb of ozone for 35 days. Soluble proteins (excluding intrinsic membrane proteins) were extracted from leaves after 3, 14 and 35 days of ozone exposure, as well as 10 days after a recovery period. Proteins (pI 4 to 7) were analyzed by 2‐D DIGE experiments, followed by MALDI‐TOF‐TOF identification. Additional observations were obtained on growth, lesion formation, and leaf pigments analysis. Although treated plants showed large necrotic spots and chlorosis in mature leaves, growth decreased only slightly and plant height was not affected. The number of abscised leaves was higher in treated plants, but new leaf formation was not affected. A decrease in chlorophylls and lutein contents was recorded. A large number of proteins involved in carbon metabolism were identified. In particular, proteins associated with the Calvin cycle and electron transport in the chloroplast were down‐regulated. In contrast, proteins associated with glucose catabolism increased in response to ozone exposure. Other identified enzymes are associated with protein folding, nitrogen metabolism and oxidoreductase activity.
Spin‐dependent transport through an Aharonov–Bohm ring with a quantum dot coupled to ferromagnetic electrodes
Authors: Wu Shaoquan , Sun Weili 
Published: May 2007

AbstractUsing the Keldysh nonequilibrium Green function and the equation‐of‐motion technique, we investigate spin‐dependent transport through an Aharonov–Bohm ring with a quantum dot coupled to ferromagnetic leads. We analyze the conductance and the tunneling magnetoresistance of this system for various values of the magnetic flux and the spin‐polarization strength and obtain some new results. Our results show that this system is provided with an excellent spin filtering property, and a large tunneling magnetoresistance and a negative tunneling magnetoresistance can arise by adjusting relative parameters, which indicates that this system is a possible candidate for spin‐valve transistors and is of importance for applications in spintronics. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum effects in (2+1)‐dimensional Dirac fermion and nodal superconductivity
Authors: Morita Y. 
Published: May 2007

AbstractWe shall discuss quantum effects in (2+1)‐dimensional Dirac fermion (nodal quasiparticle in two dimensions) and also the relevance to nodal superconductivity. For example, we focus on quantum interference effects due to defects (so called localization) in the ‘pi‐flux model’, where nodal quasiparticle realizes. It is related to the problem of e.g. graphene, cuprates and organics. Key ingredients in these problems are lo‐calization, topological defect, and quantum Hall effect (QHE). In the beginning, our emphasis is on ‘statics’ e.g. DoS, which is directly observed through the STM study. Its implication to ‘dynamics’ e.g. transport properties is also discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coherent spin transport in magnetization modulated semiconductor heterostructures
Authors: Sankowski P. , Oszwałdowski R. , Kacman P. , Majewski J. A. , Dietl T. 
Published: May 2007

AbstractThe Landauer–Büttiker formalism combined with the tight‐binding transfer matrix method is employed to model vertical coherent spin transport within magnetization modulated semiconductor heterostructures based on GaAs. This formalism provides excellent physical description of recent experiments concerning the high tunneling magnetoresistance (TMR) in (Ga,Mn)As‐based trilayers and highly polarized spin injection in p‐(Ga,Mn)As/n‐GaAs Zener diode. In particular the formalism reproduces strong decrease of the observed effects with external bias. We ascribe this decrease to the band structure effects. In the framework of the developed model, the intrinsic domain‐wall resistance (DWR) in (Ga,Mn)As is also studied and compared to experimental results. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stripes and phase separation in strongly correlated systems
Authors: Czajka K. , Maśka M. M. 
Published: May 2007

AbstractUsing classical Monte Carlo approach we analyze two‐dimensional Falicov–Kimball model away from half‐filling. Both the weak and the strong interaction regimes are considered. We found that in the former case stripe configurations are the stable ones, whereas in the latter case the phase separation minimize the energy. We present also the spectral properties of the system. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum gambling using mesoscopic ring qubits
Authors: Pakuła Ireneusz 
Published: May 2007

AbstractQuantum Game Theory provides us with new tools for practising games and some other risk related enterprices like, for example, gambling. The two party gambling protocol presented by Goldenberg et al. is one of the simplest yet still hard to implementapplications of Quantum Game Theory. We propose potential physical realisation of the quantum gambling protocol with use of three mesoscopic ring qubits. We point out problems in implementation of such game. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of deep level spectra in p‐type and n‐type GaN grown by molecular beam epitaxy
Authors: Armstrong A. , Poblenz C. , Mishra U. K. , Speck J. S. , Ringel S. A. 
Published: May 2007

AbstractDeep levels in n‐type GaN:Si and p‐type GaN:Mg grown by molecular beam epitaxy were compared using deep level optical spectrscopy (DLOS). For n‐GaN, the major bandgap states were observed to lie within 1 eV of the valence band edge. For the p‐type film, hole photoemission from deep levels at near the conduction band edge and electron photoemission from a deep level near the valence band edge were resolved. Overall, the p‐GaN filmed incorporated nearly ten times greater deep level concentration. Bandgap states attributed to residual carbon impurities with large concentration were found near the minority band edge in both films. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Flux‐biased mesoscopic rings
Authors: Dajka J. , Machura Ł. , Rogoziński Sz. , Łuczka J. 
Published: May 2007

AbstractKinetics of magnetic flux in a thin mesoscopic ring biased by a strong external magnetic field is described equivalently by dynamics of a Brownian particle in a tilted washboard potential. The ‘flux velocity’, i.e. the averaged time derivative of the total magnetic flux in the ring, is a candidate for a novel characteristics of mesoscopic rings. Its global properties reflect the possibility of accommodating persistent currents in the ring. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gain mechanisms in field‐free InGaN layers grown on sapphire and bulk GaN substrate
Authors: Dworzak M. , Stempel Pereira T. , Bügler M. , Hoffmann A. , Franssen G. , Grzanka S. , Suski T. , Czernecki R. , Leszczynski M. , Grzegory I. 
Published: May 2007

AbstractThe gain mechanisms and recombination dynamics of InGaN layers strongly depend on the structural properties of the substrate material. The 4.5 nm and 9.5 nm thick layers were grown by metal organic chemical vapor deposition on two different substrates (sapphire and GaN) with different dislocation densities. Time‐resolved photoluminescence spectroscopy at high excitation densities identifies the saturation of nonradiative recombination centers through excited carriers as a major gain mechanism. The prime argument is an unusual nonexponential luminescence decay. This was confirmed by a lower threshold of the optical gain for the structures grown on GaN with lower dislocation densities. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Intermediate frequency modes in Raman spectra of Ar+‐irradiated single‐wall carbon nanotubes
Authors: Skákalová Viera , Maultzsch Janina , Osváth Zoltán , Biró László P. , Roth Siegmar 
Published: May 2007

AbstractWe study the effect of Ar+ irradiation on the intermediate frequency modes (IFM) in Raman spectra of single‐wall carbon nanotubes. We observe new features in the intermediate frequency region from 386 to 635 cm–1 as the defect concentration increases, whereas at the same time there is a decrease of other IFM modes. After annealing in vacuum, the IFM modes recover and become similar to those of the nanotubes before irradiation. We interpret the new features in the Raman spectra as originating from the phonon density of states that becomes visible in the Raman process due to the presence of defects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)