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1.
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   

2.
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   

3.
Multichannel -type devices developed at TsNIITMASh for the automated ultrasonic inspection of cylindrical objects, such as mill rolls, shafts of turbines and compressor units, circular welded joints of thick-walled shell rings, etc., are described. These devices feature from two to eight acoustoelectronic channels. Acoustic contact occurs through industrial water. The testing is performed under workshop conditions; the object being inspected is rotated by a turning lathe or any other handling mechanism. Sonication is simultaneously performed by piezoelectric transducers (PETs) with input angles of 0, 40, 50, 60, and 70° and also by surface and head waves in order to reveal surface and subsurface flaws. A wide-span eddy-current transducer of special design is also used for this purpose. All data are stored in flash memory and retrieved on a PC located in an office. The inspection results are displayed as C- and B-type scanning defectograms. Moreover, it is possible to obtain an isometric image of flaw zones. -type devices have been used for over one and a half years in two workshops at OAO Severstal'.  相似文献   

4.
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   

5.
The design and results of tests of a vacuum feedthrough insulator for a pulsed electron accelerator with a voltage of 1 MV, a current of 20 kA, and a half-height voltage-pulse duration of 400 ns are presented. A method for distributing the voltage over the sections of the insulator due to an electron emission from specially created surfaces is proposed.  相似文献   

6.
This paper presents a systematic procedure for selecting and designing snapfits integrated into plastic parts. A classification is proposed based on the geometry of the parts to be assembled and the ease of dismantling. The part geometry influences the type and shape of the snapfit. Depending on the space available, recommendations are made for choosing from a classical straight beam shape, a tapered shape, an L shape and a U shape. The snapfit fastener may be separable if so designed. A distinction should be made between: dismantling with or without a tool (screwdriver or specialised tool); access to the insertion face only; access to insertion face and opposite or lateral faces.  相似文献   

7.
A theoretical model of the formation of rhombic (in the case of an edge texture) or square (on cubic texture) indicator patterns upon magnetization of single crystals of electrical steel orthogonally to the (110) and (100) planes is described. The model is based on a solution of Maxwell's equations for a magnetostatic problem, with magnetic permeability introduced as a tensor. Two field sources are considered as limiting cases: (a) loop, short coil; (b) semi-infinite magnet, long coil. Two cases of permanent magnet diameters are considered: thin, d = 4 mm; thick, d = 20 mm. Two cases of density of magnetic charges are considered: (a) = const; (b) = 0/ .  相似文献   

8.
This paper looks into a new area for knowledge-based system application, that of manufacturing modelling. The objective is to develop a knowledge-based manufacturing modelling system that can be used to build company-specific as-is and to-be IDEF0 models, and can therefore greatly reduce the turnaround time and effort involved in IDEF0 modelling of manufacturing systems, which can be time-consuming if done manually or even with the aid of a commercially available software package like DESIGN/IDEF. This is especially so when the systems being modelled are large and complex. Besides, there is also the inconsistency problem associated with conventional IDEF0 modelling systems owing to the terms and terminologies in IDEF0 not being precisely defined, and hence being subject to individual interpretations. In this paper, a knowledge-based IDEF0 modelling system that can not only automate the tiresome and time-consuming process of manufacturing modelling but can also eliminate the inconsistency problem is proposed. The paper explains the knowledge-based approach to automated generation of IDEF0 models, and also identifies the kinds of domain knowledge that are required for the construction of the knowledge-based manufacturing modelling system.  相似文献   

9.
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   

10.
An algorithm for calculating the scintillation coordinates developed for a large-size coordinate-sensitive detector is developed. The detector based on a liquid scintillator has nine radially arranged -174 photomultipliers. The results of simulation of the dependence of the coordinate resolution at the detector center on -quanta energy between 0.2 and 8 MeV are presented. The experimental data obtained with a collimated beam of -quanta from a 60Co source, which irradiated the central part of the detector, were processed by using this algorithm. The -ray spectrum measured by the detector and the results of determining the scintillation coordinates for a -quanta beam are presented. The accuracy of coordinate measurements at the central region of the detector with this algorithm is 10 mm.  相似文献   

11.
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   

12.
Gao  F.  Wu  G.  Stacchiola  D.  Kaltchev  M.  Kotvis  P.V.  Tysoe  W.T. 《Tribology Letters》2003,14(2):99-104
The friction coefficients of thin KCl films deposited onto clean iron in ultrahigh vacuum are measured using a tungsten carbide tip. A rapid decrease is found in the friction coefficient from 2 for clean iron to 0.27 ± 0.03 after the deposition of 40 Å of KCl. Based on previous contact resistance measurements, this was proposed to be due to the completion of the first layer of KCl. The first-layer KCl coverage was measured by adsorbing deuterium onto an iron surface partially covered by KCl, where deuterium selectively adsorbs onto the iron. This revealed that the first monolayer is complete after the deposition of 40 Å of KCl and that the first-layer KCl film coverage KCl (1) is given by KCl (1) = 1 - exp(-0.39±0.02t), where t is the film thickness. XPS data suggest that heating a KCl film to 550 K causes it to wet the surface. This leads to decreases in the friction coefficients for thin KCl films in accord with the idea that friction is reduced by the first monolayer of KCl on iron. Temperature-programmed desorption data indicate that KCl in the first monolayer is 5 kJ/mol more stable than the multilayer consistent with the wetting behavior. Finally, the kinetic data are analyzed to suggest that the first-layer film is 2.6 Å thick.  相似文献   

13.
P-odd asymmetry is measured when frequencies of switching neutron polarization exceed the frequencies of the reactor power fluctuations that govern the spectral density of noise power. A principle for recording the current signals in these measurements is described. This method was used for the first time at the Konstantinov Institute of Nuclear Physics in Gatchina (Russia). The results suggest that the accuracy of measurements at an increased equipment-switching frequency is even higher than the accuracy obtained using compensation for reactor power fluctuations; hence, this compensation becomes superfluous. Following this method, it is possible to take measurements with a single detector and to dispense with a monitor, thereby rendering the equipment and the measuring technique less complex. A strategy of measurements was developed. An experimental model of the facility was produced and tested with a small-amplitude calibration signal in the presence of reactor power fluctuations caused by rays from reaction 10B(n )7 Li* 7Li + . The results from the test measurements of the P-odd effect in reaction 35Cl(n, )36Cl are presented.Translated from Pribory i Tekhnika Eksperimenta, No. 1, 2005, pp. 62–71.Original Russian Text Copyright ¢ 2004 by Vesna, Shulgina.  相似文献   

14.
The specifics for monitoring the thickness of electrically- conductive coatings on a conductive substrate are described. Difficulties involved in designing thickness meters that assist in this task are noted. The technical characteristics and design of a -1 versatile eddy-current sensor are presented.  相似文献   

15.
This paper presents a new perspective on the calibration of industrial robotics systems by describing robot position errors as time varying variations of the actual positions of the end-effector from the target position, the error calibration of a robotics manipulator is treated as a process rather than a state. Therefore the theory of variations is applicable. The importance of distinguishing the two kinds of variations, namely random system variations and assignable variations, in a robot calibration process is demonstrated through a Monte Carlo simulation.Statistical process control techniques provide a tool for measuring and characterising the position errors of robotics manipulators. Their application in this work, not only focuses on the development of mathematical formulation of calibration models, but provides a deeper understanding of the randomness of the errors in robot systems.It is also shown that if a robot system is adjusted for its random errors to compensate for undesirable results, the resulting output will be worse than if the robot system alone was not adjusted.  相似文献   

16.
Single-electron and time characteristics of a -184U photomultiplier tube with a uviol window are presented. The -184U single-electron resolution can reach a value of 63–64%, and, in case of single-electron light-striking of the photocathode, the photoelectron transit time distribution (full width at half maximum) is 6 ns.  相似文献   

17.
A simple updating of an P 1306 spectrometer for microwave absorption measurements in a low-induction magnetic field at temperatures of down to 15 K is described.  相似文献   

18.
An electric-discharge light source, operating in the spectral range of 170–270 nm on a system of bands of Cl2 ( = 200 and 257 nm) and KrCl ( = 222 nm) molecules is described. The radiator is pumped by a low-pressure volume discharge in a spherical anode-flat cathode system of electrodes with an interelectrode distance of 6 cm, so that the plasma has no contact with the quartz envelope of the lamp. The working mixtures are P(Kr)/P(Cl2) = (40–640)/(40–280) Pa. When a dc voltage U 1 kV is applied to the discharge gap, a volume discharge exists only in a periodically pulsed mode (f = 0.1–50 kHz) and represents a source of short-wave radiation with a cylindrical working surface (1 cm in diameter and 6 cm long) and a mean radiation power of 3 W.  相似文献   

19.
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   

20.
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   

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