共查询到20条相似文献,搜索用时 144 毫秒
1.
M. M. Naim D. R. Towill 《The International Journal of Advanced Manufacturing Technology》1993,8(5):329-343
Algorithms are derived for the four-parameter transfer function S-shaped curve, using a least-squared-error (LSE) method for an exponential function. The S-shaped curve is just one in a family of industrial dynamics learning-curve models of increasing complexity which may be used to replicate and forecast the start-up of industrial innovations.Controlled experiments are undertaken, via simulation of message and noise, to test the modelling and forecasting capabilities of the algorithms. A number of strategies are introduced to improve forecasting performance, such as boots-trapping, sequential and parallel adaptation, and alternatively adopting the simplified three-parameter S-curve model.Four examples of modelling industrial innovations via the transfer function learning curve models are presented. The paper concludes that although there is now the capability to model the general four-parameter S-curve, its applications are limited. This is because simpler (and hence less accurate) transfer function models tend to be more robust. 相似文献
2.
Assoc. Professor L. P. Khoo C. L. Ang J. Zhang 《The International Journal of Advanced Manufacturing Technology》1998,14(12):928-934
This paper presents the work done to adapt a system modelling methodology, ICAM DEFinition Zero (IDEF0), to perform manufacturing diagnosis. It describes the basic notions of IDEF0 modelling and the underlying principle of a novel reasoning technique, the worst-first search, developed for manufacturing diagnosis. The reasoning technique which was originally based on graph theory and possibility theory, has been adapted to access the information stored in an IDEF0 model. Details of a prototype IDEF0-based system for manufacturing diagnosis are presented. The results of system validation based on a manufacturing system for the production of mechanical components are reported. 相似文献
3.
Khandetskii V. S. Pashchenko V. A. Matveeva N. A. 《Russian Journal of Nondestructive Testing》2002,38(9):679-694
Code combinations of 2
n
symbols +1 and –1 suggested for identification of characteristic features leading edge, trailing edge, maximum, minimum, horizontal portion, start of leading edge, end of leading edge, start of trailing edge, and end of trailing edge in a binary-code envelope of a pulse measured by an eddy-current transducer (ECT) scanning a tested surface generate a group code. This group code ensures for four levels of noise immunity the maximal likelihood in identification of reference sequences distorted by noise. The structure of a product code, which is also generated by the reference fragments, results in a higher capability of correcting for errors in moving samplings of signal envelopes, in particular, it reduces the degree of uncertainty in identification of the most important features of ECT pulses. The paper suggests simple decoding algorithms and regular logical structures that provide a high efficiency of the procedure eliminating errors in binary sequences of coded envelopes. 相似文献
4.
M. Chan Professor B. Szabados 《The International Journal of Advanced Manufacturing Technology》1998,14(3):220-227
One of the goals of operating a tandem manufacturing system with finite inter-stage storage and asynchronous operations is to meet the demand without over-producing, under-producing or carrying large quantities of material in storage. We believe that analysing the operation of such a system on a real-time basis helps achieve this goal. The first step in this real-time analysis would be to quantitatively associate the causes and effects of over-production or under-production as they occur. This requires determining the cumulative effect that the performance that any stage has on the system, based on its history, the current system state and the interrelationships between the stages. This paper proposes a method which first represents uniquely and completely each stage and surrounding storage as an element. While this system, which consists only of this simple type of element functions in exactly the same way as the original one, each element is put into an ideal world for decoupled measurement. Though an element behaves in exactly the same way whether it is in the ideal world or in the real world, the elapsed times in the two worlds since the beginning of production can be different, since the responses (occurrences and durations of the blockings and starvations) of the two worlds can be different. A phase parameter is introduced for each element to represent this difference. Once the formation of the phase parameter of the output element is formulated, quantitative relationships between causes and effects of over-producing or under-producing can be explained as they occur. 相似文献
5.
O. V. Fateev G. A. Cheremukhina S. P. Chernenko Yu. V. Zanevsky H. Lauter V. V. Lauter S. V. Kozhevnikov Yu. V. Nikitenko A. V. Petrenko 《Instruments and Experimental Techniques》2001,44(2):137-143
A linear detector of thermal neutrons, developed at the Laboratory for High Energies (Joint Institute for Nuclear Research), is used in the polarized-neutron spectrometer of the -2 reactor (JINR). The data are acquired in the regime of frame-by-frame survey to select neutrons with a wavelength = 1–12 Å by the time of flight. The neutron-detection efficiency is 70% for a wavelength of 2 Å. The detector exhibits a low sensitivity to -rays, a differential nonlinearity of 1.5%, and a spatial resolution of 1.5 mm at counting rates of 105events/s. 相似文献
6.
A. S. Boriskin Yu. V. Vlasov A. V. Vas'kin V. A. Demidov V. A. Ionov S. V. Kutumov A. P. Romanov E. I. Shchetnikov 《Instruments and Experimental Techniques》2004,47(5):639-644
A transportable standard module developed at the Institute of Experimental Physics as a component of an energy source for modeling current pulses of positive lightning is described. The source is designed as a combination of several unified helical explosion–magnetic generators with output transformers and an inner diameter of the stator of 200 mm. According to our calculations, the source generates current pulses with an amplitude of up to 100 kA in loads with an inductance of 100 H and a resistance of several tens of ohms. The results from testing a typical module operating with a circuit having an inductance of 100 H and a resistance of 4 are presented. The experimental data coincide well with the results of a mathematical simulation of the module's operation. 相似文献
7.
V. V. Dubinina N. P. Egorenkova V. I. Krotkova E. A. Pozharova V. A. Smirnitsky V. V. Shamanov 《Instruments and Experimental Techniques》2002,45(5):655-659
FoMos makes double-sided emulsion tapes. Films of desired size cut from such tapes are used as emulsion trackers. The technique for measuring distortions is described, and the results of measurements are presented for several films cut from different sections of a standard piece of double-sided tape with a length of 7 m and a useable width of 20 cm. The standard plastic base of the tape under investigation is 190 m thick; 50-m-thick layers of diluted PX3 emulsion–gel are applied to its opposite sides. 相似文献
8.
Dr Chris R. Chatwin Hussein A. Abdullah Ian A. Watson 《The International Journal of Advanced Manufacturing Technology》1996,11(5):381-386
In recent years, there has been an increasing interest in the mechanisms and structure of scheduling in a computer-integrated manufacturing (CIM) environment. This has led to the development of new scheduling models, such as Petri nets, time-augmented Petri nets, fuzzy scheduling models and neural net scheduling models. A fundamental objective of any scheduling system is event synchronisation and optimisation of command, communication and control C3 between each active node of the overall CIM structure. CIM scheduling can be regarded as a nonlinear dynamic control process, whereby, the feed forward or feedback elements are the scheduling priorities that enable the manufacturing organisation to remain within a steady-state profit margin. However, in each different hierarchy level of the organisation, randomness phenomena in the C3 environment can be observed, i.e. events in a particular department or organisational level cause a perturbation elsewhere in the manufacturing organisation. Furthermore, these changes are constrained by the framework of rules pre-set by the organisational structure and business corporate strategy. To a first approximation, these cause-and-effect phenomena can be viewed as deterministic changes which may result in deterministic chaos. In this paper, a self-organising compensating information system (SOCIS) is presented. This system is designed utilising knowledge control modelling (KCM) topology with its architecture based on the principles of client-server and a second-order proportional-integral-differential knowledge-based management system (PID-KBMS). 相似文献
9.
S. V. Chuklyaev Yu. N. Pepyolyshev V. P. Alyokhin 《Instruments and Experimental Techniques》2001,44(2):144-148
A promising design of a -type two-section gas-filled ionization chamber is described for the first time. A relationship between the design parameters, gas pressure, and characteristics of the material is determined, under which full compensation of the background currents from the -radiation and the measurement of thermal neutron fluxes in a range of 400 to 7 ×109cm–2s–1at a load characteristic with a 5% nonlinearity are provided. Test results of the chamber are presented. 相似文献
10.
V. G. Brovchenko A. M. Kirichenko N. A. Petrov V. V. Fedorenko 《Instruments and Experimental Techniques》2002,45(6):776-779
The mediator unit (mediator) generates a strobe pulse when a scintillation signal is at its maximum (peak moment). The strobe pulse starts the analog-to-digital converter, which performs digitization on a special command. The parameters of the mediator circuit presented are optimized to handle the signals from the detection unit, which comprises a CsI(Tl) scintillator, a silicon p–i–n photodiode, and a squaring amplifier. The maximum input-signal amplitude is 5 V, and the time of rise to the maximum is 7 s (quasi-Gaussian signal). When such signals are used, the strobe pulse is shifted in time with respect to the signal peak by 5 ns if the amplitude of the analyzed signals varies from 5 to 0.2 V. The unit is tested in operation (with minimal circuit alterations) over a rise-time range from 1 s (NaI(Tl)) to 20 s. The mediator includes a baseline-potential restorer and an adjustable-threshold comparator. Owing to these features, the mediator can also be used as an amplitude integral discriminator and can operate from signal sources with unstable base levels, including systems that require a signal time lock. When the recorded signals are superimposed on the leading and trailing edges, a considerable part of the superimposed signals is rejected. 相似文献
11.
Many large claims have been made about the payoffs that can and must be made from business process reengineering (BPR). Information technology is usually ascribed a critical role in BPR success. There is still a shortage of detailed information on the BPR phenomenon in terms of costs and results. This paper uses data from 168 UK-based organizations surveyed in the BPR heyday (1994–1996 period) to establish the size of expenditure, types of costs, and the types and size of benefits anticipated and experienced among these organizations. The majority were found to be aiming low and hitting low, though there was evidence of a small minority of organizations achieving something approaching what could be described as breakthrough results. The reasons for these results are discussed in detail and are related to the wider literature. 相似文献
12.
M. Kalta B. J. Davies 《The International Journal of Advanced Manufacturing Technology》1994,9(5):291-304
EXCAP, is a knowledge-based process-planning system for rotational components. CADEXCAP is software which has been developed to integrate EXCAP with CAD systems via IGES (Initial Graphics Exchange Specification). CADEXCAP deciphers a full 2D model of a turned component developed on a CAD system and then via IGES it fully automatically generates a product model in a format suitable for EXCAP. CADEXCAP has a modular structure of three modules: readiges, preprocess and postprocess. The preprocess module, which is the concern of this paper, was written in FORTRAN77 to pre-process the IGES entities. The pre-processing process includes two main tasks. The first task is to extract only the necessary information from the IGES entities. The second task is to locate the entities in one coherent coordinate system, which is the model space coordinate system, using transformation matrices. 相似文献
13.
The operation features and the main technical characteristics of the -12 eddy current flaw detector are considered. A method is proposed for testing complex-shaped parts with the use of holding attachments and a specialized transducer with a slanted sensitive element. The capabilities of the device in assessing the hazard level (depth) of a flaw are shown. The distinctive features of the -12 eddy current flaw detector are presented. 相似文献
14.
S. P. Avdeyev V. A. Karnaukhov V. D. Kuznetsov L. A. Petrov V. K. Rodionov W. Karcz M. Janitcki H. Oeschler 《Instruments and Experimental Techniques》2001,44(5):634-637
A -activation method for measuring the thickness of thin CsI(Tl) polycrystalline films deposited by evaporation on large-area (150 cm2) backings is described. Scintillators specially prepared to be used in the FASA installation as detectors of intermediate-mass fragment multiplicity were measured. It was shown that the distribution of the film thickness along the scintillator surface can be determined by -activity scanning. It has been shown that the film thickness decreases from the middle of the backing to its periphery by 25% for scintillators with a linear size of 140 mm. 相似文献
15.
Y. Kao Dr Y. B. Moon 《The International Journal of Advanced Manufacturing Technology》1997,13(9):649-657
Most of the part family formation methods are concerned with how to form the families as opposed to how to identify the families. However, a more appropriate approach would be to identify naturally occurring families since these methods are based on the production flow analysis, which uses already implemented routing data. This paper presents a new approach using the memory association of neural networks to identify naturally existing families. The developed system, Feature-Based Memory Association Network (FBMAN), operates by the exhaustive association approach which deals with the difficult problem of exceptional parts. Comparison with the results generated by other methods proves the effectiveness of FBMAN. 相似文献
16.
A Nd:YAG laser with intracavity polarization decoupling of channels is designed to be used in devices for the recording and development of holograms on photothermoplastic materials. The device ensures the obtainment of nanosecond radiation pulses (30 ns, 0.01 J) of the second harmonic for exposure of photothermoplastic media and millisecond (4 ms, 0.5 J) IR radiation pulses at the fundamental frequency for proximate development of relief-phase holograms on photothermoplastic materials. 相似文献
17.
The characteristics of a commercially produced -311 avalanche photodiode are studied. The receiver, which features thermoelectric cooling of the avalanche photodiode, is designed to receive the 2-Mbit/s laser communication signals of a geostationary satellite with an 8-MHz bandwidth of the electronic signal and a 0.15-nW threshold sensitivity. These parameters correspond to the requirements for the reception of a laser communication signal if an optical system with an aperture 0.7 m in diameter is used. 相似文献
18.
V. A. Demidov L. N. Plyashkevich A. S. Boriskin S. A. Kazakov E. V. Shapovalov A. P. Romanov E. M. Dimant S. N. Golosov 《Instruments and Experimental Techniques》2002,45(4):540-543
Experimental data on a helical magnetic-cumulation generator with an output step-up transformer formed by two coaxial solenoids is presented. The inner diameter of the helix is 50 mm. Compared with the transformers described earlier, this transformer has a smaller size. The transformer can feed an energy of 1 kJ into a 100-H high-impedance load. 相似文献
19.
V. I. Suslyaev T. D. Kochetkova V. A. Zhuravlev S. V. Sudakov 《Instruments and Experimental Techniques》2003,46(5):672-676
An automated setup for measurements of the temperature dependences of permittivity spectra is described. It uses an irregular microstrip resonator and allows measurements to be performed at a junction of methods using lumped elements and electrodynamic systems with distributed parameters. Measurements can be carried out without expensive thermostabilization devices in the temperature range of 200–350 K with a step of 1 K. The temperature dependences of the permittivity of polar liquids—water, methanol, and ethanol, whose dielectric relaxation regions lie within the frequency range of 0.1–1.25 GHz—are presented. Comparing the measured values of the permittivity to the Debye curve calculated from the reference data shows agreement within the limits of 3% for and 1% for . The random error of measurements was 2–3% for and 5–7% for . 相似文献
20.
V. M. Vetoshkin O. K. Vasyuta P. N. Krylov S. S. Alalykin 《Instruments and Experimental Techniques》2002,45(6):843-845
A high-frequency magnetron reactive-ion etching system for the high-speed quartz glass surface treatment is described. The scanning assembly of the magnetron is located in a separate chamber pumped down to a pressure of 10–2 Pa. This ensures a highly uniform etching and a high magnetic induction on samples, making it possible to reduce the cathode thickness. The quartz etching was studied in SF6, CF4, and CHF3 with the magnetron operation with and without scanning. The maximum etching rates of 1.6 m/min (with scanning) and 4.2 m/min (without scanning) were attained in CHF3 with a 1-Pa pressure and 700-W discharge power. 150-m-depth 4-mm-diameter pits were obtained by the quartz etching without scanning. With an increase in the pit depth from 150 to 250 m, the etching rate was reduced from 4.2 to 2.5 m/min. 相似文献