bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antiferromagnetic‐to‐ferromagnetic transition induced by aluminum in the Ti(Fe1−xAlx)2 intermetallic compounds: a 57Fe Mössbauer spectroscopy study
Authors: Delyagin N. N. , Erzinkyan A. L. , Parfenova V. P. , Rozantsev I. N. 
Published: July 2007

AbstractMössbauer spectroscopy has been used to investigate the hyperfine field distributions and the local spin configurations of Fe atoms in the magnetically ordered Ti(Fe1−x Alx)2 compounds. The evolution of the spin arrangement of the Fe atoms was observed over the concentration range 0 ≤ x ≤ 0.25 at 5 K. The Al impurity suppresses the ferromagnetic exchange in the Fe(6h) layers and simultaneously provides the conditions for a transition of the Fe(2a) atoms, which are nonmagnetic in the TiFe2 compound, to the states with nonzero magnetic moment. The magnetic behavior of the Fe(2a) atoms is the key factor governing the anti‐ to ferromagnetic transition in the Ti(Fe1−x Alx)2 compounds. The magnetic ordering temperatures of the Ti(Fe1−x Alx)2 compounds were determined. In addition, the parameters of the electric‐field gradient in TiFe2 as well as the relationship between the value of the magnetic moment of the Fe atom and the type of atomic configuration were discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coexistence of spin‐singlet s‐ and d‐wave and spin‐triplet p‐wave order parameters in anisotropic superconductors
Authors: Gonczarek R. , Krzyzosiak M. , Jacak L. , Gonczarek A. 
Published: July 2007

AbstractA two‐dimensional model of an anisotropic superconductor with a relatively wide partially filled conduction band and a dispersion relation implying singularities in the density of states is considered. Employing the conformal transformation method and choosing the Fourier harmonics as the complete and orthogonal basis for C4v irreducible representations the symmetry of the superconducting order parameter is identified. Detailed numerical calculations are carried out for the two‐dimensional tight‐binding band model and compared with the results obtained within the BCS‐type approximation. Diagrams of stable superconducting states in the coordinates η = 2t1/t0 and n (carrier concentration) are outlined. Symmetry relations with respect to replacing η with −η are found and discussed. The problem of coexistence of s‐, p‐ and d‐wave order parameters is addressed. The triple points are localized and supreme transition temperatures are evaluated. It is shown that the results obtained for various values of the pairing amplitude V1 coincide, whereas the tight‐binding results and some obtained within the BCS‐type approximation are dissimilar. The influence of the attractive or repulsive onsite interaction on the stability of the s‐wave order parameter is explained. The developed and widely illustrated formalism can be easily applied to some more composed models. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
TiSi2 nanostructures – enhanced conductivity at nanoscale?
Authors: Enyashin Andrey N. , Gemming Sibylle 
Published: July 2007

AbstractThe structural properties, the stability and the electronic properties of the nanotubes of titanium disilicide are studied using the density‐functional‐based tight‐binding method (DFTB) and compared with ones of the bulk and monolayered TiSi2. These nanotubes were found to be more stable, than a TiSi2 monolayer. All low‐dimensional TiSi2 systems are metallic with enhanced densities of Ti 3d‐states at the Fermi level. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On magnon energy branches of multilayer ferrimagnetic superlattices [Reply to the comment “Boson Green's functions treatment of three‐layer ferrimagnetic superlattice”, phys. stat. sol. (b) 244, No. 10, 3750–3753 (2007)]
Authors: Qiu Rong‐ke , Zhang Zhi‐dong 
Published: July 2007

AbstractThe magnon energy branches of multilayer ferrimagnetic superlattices are discussed, as regards the linear spin‐wave approach and Green's function technique. It is argued that negative energy branches in the spin‐wave spectra of the ferrimagnetic systems have physical significance, which is responsible for the zero‐point motion (i.e. the quantum fluctuations) in the ground state, since the sign of ωl(k) indicates the direction in which the spin‐wave mode propagates. On boson Green's function treatment, the results calculated for physical properties with consideration of negative energy spectra are correct and the consequent conclusions do not need to be re‐examined. Even for the definition of energy gaps, nothing is wrong from the theoretical point of view if one considers both negative and positive energy spectra, but one may need to consider two different definitions (one considers the negative/positive energy spectra; the other only the positive ones), from the experimental point of view, to compare both of them with experimental data, in an attempt to detect whether the negative energy branch does excite or not. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Weibull probability paper used on highly stressed bimodal components
Authors: Drapella Antoni 
Published: July 2007

AbstractUnder high stress conditions the ‘freak’ and ‘strong’ subpopulations lie very close to each other on the time scale. It is easy to ‘read’ such a time‐to‐failure distribution as unimodal, especially when probability paper is used. This paper puts forward Parzen'sestimator of the probability density function as a very useful method of indicating the ‘freak’ subpopulation.
Quantitative effects of electrical and vibrational stresses on reliability
Authors: Wong Kam L. 
Published: July 2007

AbstractThis article presents some details on how electrical and vibrational stresses exacerbate failures. This is one of a series of articles on similar subjects by this author. One electrical defect type is pin‐holes in oxide layers in ICs. Electrical leakage current through a low insulation pin‐hole could cause temperature rise and ultimately, when electrons of sufficient energy causing an avalanche, a thermal runaway condition could develop and maintain an electrical short. On the other hand electromigration could cause conductor opens. Aircraft data indicated that vibration related failures constituted more than 14 per cent of the total number of field failures. Fatigue failures can be directly related to S/N curves of stress to number of cycles to failure. Some measurements indicated that for a particular piece of equipment tested the time to failure varied inversely as the fourth power of vibrational acceleration; and failures of specific groups of component part types were sensitive to particular vibrational acceleration levels. Much information exists that gives quantitative measures on how stresses exacerbate failures. However, there is still a big gap in the relationship between the engineering fundamentals and the failures experienced. The author urges the readers to join force to develop a new reliability engineering foundation based on relationships of defects, failure mechanisms and stresses from which future reliability predictions and reliability analyses can be conducted.
Forecasting reliability growth
Authors: Lloyd David K. 
Published: July 2007

AbstractThis paper describes a method for estimating and forecasting reliability from attribute data, using the binomial model, when reliability requirements are very high and test data are limited. Integer data—specifically, numbers of failures — are converted into non‐integer data. The rationale is that when engineering corrective action for a failure is implemented, the probability of recurrence of that failure is reduced; therefore, such failures should not be carried as full failures in subsequent reliability estimates. The reduced failure value for each failure mode is the upper limit on the probability of failure based on the number of successes after engineering corrective action has been implemented. Each failure value is less than one and diminishes as test programme successes continue. These numbers replace the integral numbers (of failures) in the binomial estimate.This method of reliability estimation was applied to attribute data from the life history of a previously tested system, and a reliability growth equation was fitted. It was then ‘calibrated’ for a current similar system's ultimate reliability requirements to provide a model for reliability growth over its entire life‐cycle. By comparing current estimates of reliability with the expected value computed from the model, the forecast was obtained by extrapolation.
Research into the use of statistical quality control in british manufacturing industry‐part II
Authors: Followell Roy F. , Oakland John S. 
Published: July 2007

AbstractThe work described in this paper is part of a large. Government‐funded investigation into the usage of statistical methods of quality control (SQC) in British manufacturing industry. This paper reports the results of work in seventeen companies on the implementation of SQC. The results are summarized by the use of evaluation scales and attributes, and measures of success and barriers are identified. Some general conclusions are drawn which point to a methodology for the introduction of SQC.
Reliability characterization of a 3‐mum cmos/sos process
Authors: Dugan M. Patrick 
Published: July 2007

AbstractA continuing study of advanced short‐channel CMOS/SOS arrays has been carried out at the RCA Microelectronics Center (MEC) and at RCA Laboratories, Princeton, NJ, since 1981. A technique to assess the reliability of a new process relatively quickly consists of high‐tempertaure accelerated stress testing of ICs by maintaining the temperature at 200°C, while biasing half the inputs at the positive supply voltage and half at ground. The results of these accelerated stress tests together with device analysis, were used to calculate a failure rate and to determine that time‐dependent dielectric breakdown (TDDB) is the principal failure mechanism. No mechanism unique to the CMOS/SOS technology has been observed.
Some factors to consider in developing a quality‐related feedback system
Authors: Staveley J. C. , Dale B. G. 
Published: July 2007

AbstractThis paper reports on work which has been carried out in an attempt to identify some of the key factors in the development of a quality‐related feedback system associated specifically with major installations. The main reasons why the majority of manufacturers have not developed systems to obtain data from users is due to the difficulties encountered in obtaining meaningful information. The current main sources of feedback are from technical sales representatives, customer complaints and internal feedback obtained from monitoring recurrent orders for spares. The information being generated by users of computerized maintenance systems has, to date, been little used by manufacturers to initiate quality‐improving changes. However, most manufacturers said they would use such data if it was offered. It is also pointed out that designers can play a key role in improving the quality of plant and equipment by requesting feedback information in those areas where there might be design uncertainty and by giving consideration to the possibility of condition monitoring when a product is being designed.
The inherent unreliability of reliability data
Authors: Mallagh C. 
Published: July 2007

AbstractThe availability of good data is crucial to good reliability prediction. Two contrasting cases are noted: (1) when a large amount of experience with components is available but data are not collected and (2) when systems are so innovative that no reliability experience is available. The relationship of reliability to incompleteness of knowledge and the acausal nature of statistical/probabilistic models is discussed. The difficulty of assigning any absolute similarity between any one component and the members of a particular reliability set is outlined. It is concluded that engineering judgement must always play a vital role in reliability estimation.
Signal‐to‐noise ratio development for quality engineering
Authors: Kapur Kailash C. , Chen Guangming 
Published: July 2007

AbstractDr. Taguchi developed the concept of signal‐to‐noise (SN) ratio in quality engineering to evaluate the performance of a system. The objective is to develop systems which are robust against noise factors. The SN ratio indicates the degree of the predictable performance of a product or process in the presence of noise factors. Parameter design of the Taguchi method optimizes the SN ratio in the domain of control factors, so that performance could be made insensitive to the noise factors in order to improve product quality. If the domain of the control factors is a continuous space, the problem is a non‐linear programming problem. Usually, in practice, there are only a few available levels for the control factors. Thus, experimental design methods can be useful for such problems. The SN ratio for four cases of dynamic characteristic problems is developed in this paper. This paper also gives the method to compute SN ratios for both equispaced and non‐equispaced intervals for levels of signal factors. Two examples are presented to illustrate the method.
Application of Taguchi methods to surface mount processes
Authors: Bandurek G. R. , Disney J. , Bendell A. 
Published: July 2007

AbstractThis paper describes the implementation of a Taguchi experiment for the placement of surface mount components as part of a process at Mars Electronics. The justification for the experimental work, the practical problems in its implementation and the significance of the results obtained are described. The experiment is seen as part of a programme and the implications of the results obtained for subsequent experimentation are discussed.
Interval reliability of spare part stocks
Authors: Bazovsky Igor , Benz Glen 
Published: July 2007

AbstractProbability goals are commonly used in conjunction with Poisson‐distributed variability to estimate initial pipeline spares requirements for aircraft organizations. An analysis of field data indicates that these deployment models may significantly underestimate spares acquisition quantities required in order to maintain probability goals throughout a system life cycle. This paper defines reliability of spare part stocks as the probability that these stocks will satisfy demands throughout a calendar time interval which begins at random points in the life cycle. Five models for spares planning were applied to field data from a small aircraft organization. The common goal in these analyses was based on military logistic standards: 0.99 probability for each part type over a replenishment interval of 360 h. Two initial interval (Poisson) models produced spares requirements averaging 273 units. The average for the three limiting (non‐Poisson) models was 3630 units. The limiting models also made it evident that spares must be purchased to refill the pipeline several times in a 20 year life cycle. It is concluded that a limiting buffer stock model is most realistic for planning normal spares requirements and that a renewal model should be used if the pipeline could be severed during surge periods of activity.
Designing a software reliability programme
Authors: Genadis Themis C. 
Published: July 2007

AbstractDesigning reliable software is becoming an ever increasing problem because the high cost of software is largely due to reliability problems. The costs of finding and fixing the errors, better known as maintenance and testing costs, account for as much as 80 per cent of the total cost of the final software product. Software developers now have an even greater interest in preventing errors from making their way into the software and finding the errors that are present in the early stages of development. Precise software design, coding and testing play an important role. This paper presents a management plan for implementing a software reliability programme at a small software industry where no reliability programme yet exists and no reliability programme is yet established.
Measuring process capability using indices — some new considerations
Authors: Porter Leslie J. , Oakland John S. 
Published: July 2007

AbstractProcess capability indices are key measures in the context of never‐ending improvement in quality. The capability of a process and the effectiveness of control charts are directly related. For samples of size 2 or greater, a Cpk value of 2 ensures that the control chart gives an immediate warning of the potential danger of producing material outside the specification following a shift in the process mean. Capability studies usually result in single point estimates for Cp and Cpk. This ignores sampling variation. More useful estimates can be obtained by constructing confidence intervals for Cp and Cpk. Evaluation of process capbility is relatively easy when a single variable describes the process. However, most processes are multivariate in nature and this makes it difficult to assess the overall capability of the process.
Control of a planar arm by nonlinear feedback gains
Authors: Wongchaisuwat C. , Donne J. D. , Özgüner Ü. , Hemami H. 
Published: July 2007

AbstractThe control of a three‐link planar robot, whose parameters roughly match a small commercially available arm, is considered. The end effector of the arm moves along a specified trajectory on a surface with dry friction while maintaining a prespecified constant pressure against the surface both with and without force sensors at the tip. A control strategy is presented with nonlinear position and velocity error feedback gains which are state dependent. Digital computer simulations of the motion are provided for comparison purposes and for demonstrating the effectiveness of this strategy.
Computer architecture for intelligent robots
Authors: Kanayama Yutaka , Yuta Shin'Ichi 
Published: July 2007

AbstractThis article proposes a computer architecture suitable for intelligent robots, especially for self‐contained intelligent mobile robots. The main principles proposed by the authors are: (1) The robot should be a multiprocessor system with a master, several slave modules and a console. A simple star connection is employed. (2) The master carries user's programs written in a high level language with which a programmer is able to use all basic functions in the robots. It should have a special purpose operating system. (3) Each module is an independent microcomputer system loosely coupled to the master and dedicated to an elementary function such as manipulation, locomotion, sensing, or planning. (4) A serial TTL level or RS232C interface is employed between the master and each module. Two self‐contained robots, Yamabico 9 and 10, constructed under these design principles have demonstrated the effectiveness of this proposed architecture.
Experiments on manipulator gross motion using self‐tuning controller and visual information
Authors: Chiu T. H. , Koivo A. J. , Lewczyk R. 
Published: July 2007

AbstractA picture of a scene is used to extract information for an adaptive control algorithm. The object of interest is first located by means of a classifier. The position and orientation of the object are determined from a binary picture. The desired path that the gripper of the manipulator is to follow is specified by discrete points, first in the Cartesian and then in the joint coordinate system. The adaptive self‐tuning controller is outlined. The controller design is based on a time series difference equation model in which the parameters are estimated on‐line. The gains of the controller are tuned so that a quadratic performance criterion is minimized. The performance of the system designed is then tested experimentally, and the results are presented.
Multifunctional optical proximity sensor using phase modulation
Authors: Masuda Ryosuke 
Published: July 2007

AbstractA proximity sensor is defined as the noncontact sensor of end‐effector, and is one of the most important sensors for robot control. This paper deals with a new type of proximity sensor which has the capability of measuring spatial information, such as gap distance, inclination angles, and the angular positions of object particles. The measuring principle of the sensor is based on the phase shift of a modulated light signal. For this purpose, six light sources are placed on a cross‐shaped pattern that is centered by a photodetector, and the power of light sources are modulated by different phase sine wave signals. The distance and angles can be measured by investigating the received phase information at the predetermined emitting pattern. By experimental measurement, the characteristics of this sensor are obtained and the effectiveness of the sensor is confirmed.
A simplified interpolation and conversion method of contour surface model to mesh surface model
Authors: Cheng K. , Idesawa M. 
Published: July 2007

AbstractContour line type representation is useful for understanding the surface structure qualitatively to a human. However, for the computer handling, a contour line model may not be suitable and it is required to be converted to the other type model such as a mesh surface model. It may be a problem how to decide mesh data on a mesh line where there are fewer points intersecting with contour lines. In this article, the authors propose a new method to convert a contour line model to a mesh surface model with minimum errors. Mesh lines (equivalent to the planes intersected with contour surface) located on the contour surface and intersected with contour lines are calculated. A mesh line which has maximum number of effective sampling points (that means maximum number of intersections with contour lines, and hereafter referred to as latter) is selected and a sectional shape along this mesh line is decided. The sectional shape is represented by spline curve with parameters, so that the mesh point data on the mesh line can be determined easily, and these decided mesh points are regarded as equivalent as intersection with contour lines. The above processes are repeated until all mesh lines which have intersection points or obtained mesh data have been chosen and calculated. Thus we can convert a contour model to a mesh surface model with minimum loss of contour line informations.
Microcomputer‐based robot dynamic sensing using linear array sensor for object recognition and manipulation
Authors: Luo Ren C. 
Published: July 2007

AbstractThis article presents a microcomputer‐based robot dynamic sensing system by the use of the linear scanning approach for object recognition and manipulation. In this research, a 512 × 1 solid‐state photodiode linear array sensor is used for dynamic scanning the object to be identified. An experimental prototype is built, which consists of a fully opened parallel jaw gripper and a 360d̀ turnable pedestal located between the jaws of the gripper. The sensor with the lens is mounted near the horizontal edge of one side of the gripper, and the illumination source is located directly on the other finger. The object to be identified is placed on the turnable pedestal. The simulated robot gripper can move vertically and the object will be scanned providing a two‐dimensional image of the object. The object can be scanned in different views by adjusting the angle of the turnable pedestal. All the binary images which result are further analyzed for recognition and manipulation purposes. A Compaq microcomputer based on the Intel 8088 microprocessor is used as the host. A special interface between scanned video output, CPU, and video RAM memory is built and successfully tested.
Recognition of geometrical shape by a Robotic Probe
Authors: Hemami Hooshang , Goddard Ralph E. 
Published: July 2007

AbstractA number of issues pertaining to the automatic recognition of the shape of known and unknown surfaces and objects by tactile probing are discussed and formulated for a planar robotic probe. The dynamics of the robotic probe are presented. Sensory and computational requirements are outlined. Several methods for deriving parameters that describe a quadratic shape are exposed. Digital computer simulations are used to demonstrate and compare three linear algorithms in estimation of parameters of a quadratic surface.