Test Layout Research Articles

Design and implementation of cancellation tasks for visual search strategies and visual attention in school children

We propose a computer-assisted cancellation test system (CACTS) to understand the visual attention performance and visual search strategies in school children. The main aim of this paper is to present our design and development of the CACTS and demonstrate some ways in which computer techniques can allow the educator not only to obtain more detailed information of visual search strategies but also to identify the problems of visual attention in school children. We have built a system that utilizes a graphic tablet connected to a PC to monitor the trace of visual search paths as well as the accuracy of visual search responses in school children during the test administration. The preliminary results show that there were no significant difference in correctness between sex, test layouts, and search patterns, except for the performance on different test forms (symbol vs. Chinese radical). The related factors that affect visual search behavior are also discussed.

Design and Construction of Three Instrumented Test Piles to Examine Time Dependent Pile Capacity Gain

Abstract Three heavily instrumented test piles were designed, constructed, and installed at a bridge reconstruction site in Newbury, Massachusetts as part of a research initiative into time dependent pile capacity gain. Pile instrumentation consisted primarily of an alternating pattern of piezometers and strain gages, allowing for correlation between pile capacity gain and excess pore pressure dissipation along discrete pile segments. Additional instrumentation within the piles included accelerometers, telltales, and radial pressure cells, allowing monitoring of total pressure at the pile wall. Standard dynamic gages (strain gages and accelerometers) were also attached to the piles during dynamic testing. A total of 86 vibrating wire, 17 electrical resistance, 17 telltales, and 4 piezo-resistive gages were installed within the test piles to record strain, displacement, pressure, and acceleration. This paper describes (i) the initial installation location of the test piles, (ii) the design and layout of the individual test piles, (iii) the selection and installation design of the individual instrumentation within the test piles, and (iv) assembly of the test piles. Sample measurements of the various instruments and a summary of the instrumentation performance are also presented.

Normes OEPP . EPPO Standards

Normes OEPP . EPPO Standards

Numerical assessment of axial pile group response based on load test

Axial pile load tests are considered within the design procedure of most major construction projects that include pile foundations, aiming to determine both the ultimate bearing capacity and the pile stiffness at working load level. Commonly used pile spacings of 3–4 pile diameters between the test pile and the reaction piles cause significant interaction with drastic effect on to the load-settlement relationship. The objective of this paper is to evaluate the influence of this interaction on both bearing capacity and stiffness of single piles and pile groups. For this purpose, a back analysis of a pile load test was initially performed which facilitated the determination of the single pile response and the verification of the soil properties. Subsequently, a numerical analysis was carried out to establish load-displacement relationships for several different layouts of pile groups. Based on these non-linear analyses the effect of the interaction was quantified for both the pile load test and pile group layouts examined.

Characterization and modeling of oxide chemical-mechanical polishing using planarization length and pattern density concepts

Chemical-mechanical polishing (CMP) has emerged as the dominant dielectric planarization method due to its ability to reduce topography over longer lateral distances than earlier techniques. However, CMP still suffers from pattern dependencies that result in large variation in polished oxide thickness across typical chips, which can impact circuit performance and yield. A comprehensive semiphysical pattern dependent model of the CMP process, integrated with a parameter extraction and process characterization methodology, has been developed to enable accurate and efficient prediction of post-CMP oxide thickness across patterned chips. In the characterization phase, test wafers are polished to obtain model parameters for the desired CMP process. Standard test layouts have been defined which consist of regions with different feature density and pitch; a new contribution is the inclusion of "step density" structures which provide large abrupt post-CMP thickness variations to improve parameter extraction. The key extracted parameter which characterizes the particular CMP process is the planarization length.

A study of multiple scattering effect with 10 kV e-beam system

Multiple scattering effect is discussed with a low voltage e-beam system. A test layout is designed to figure out the multiple scattering effect. A dark erosion is studied to identify the scattering range. The range is found to be as far as ∼15mm with our 10kV e-beam system. The effective scattering doses are 5.6% an 5.3% in terms of CD variation for beam spot sizes of 0.15um and 0.3um, respectively. CD variation between features in non-multiple scattered area and those in multiple scattered is 22nm–31nm that is not negligible for small features.

Real time proximity effects neurocorrector

A method for the proximity effects correction in Electron Beam Lithography for layouts with critical dimensions below 180nm is proposed. A parallel processing system based on an artificial neural networks is suggested as a solution to the problem. The synthesis of the architecture as well as the training algorithms for such neurocorrection system are presented. The algorithm for the learning vector generation is based on a discrete iterative regularisation. Several results of the correction process for different test layouts are presented. Error analysis of the error measure is presented. The difference between the target dose and the doses deposited in each exel after the correction process is smaller than 5%. As an hardware implementation of the real time proximity effects corrector the RBF (radial basis functions) neural system is proposed. Simulations of the Gaussian synapse cell have been done. Results of our simulations assure that our neurocorrector can precompensate for one exel from the layout in less than 60ns.

NASA B-757 HIRF test series low power on-the-ground tests

The data acquisition phase of a program intended to provide data for the validation of computational, analytical and experimental techniques for the assessment of electromagnetic effects in commercial transports, for the checkout of instrumentation for following test programs, and for the support of protection engineering of airborne systems has been completed. The initial phase involved on-the-ground electromagnetic measurements. Measurements were made of the fields coupled into the aircraft interior and signals induced in select structures and equipment under controlled illumination by RF fields. A characterization of the ground was also performed to permit ground effects to be included in forthcoming computer modeling exercises. A series of fly-by experiments were conducted in early 1995 in which the NASA B-757 was flown in the vicinity of a Voice of America station (/spl sim/25 MHz), a fixed transmitter driving a log periodic array (172 MHz), and an ASRF radar at Wallops Island (430 MHz). In this paper, the overall test program is defined with particular attention to the on-the-ground portion. The test rationale, test layout, and samples of the data are described. Samples of some inferences from the data that will be useful in protection engineering and EM effects mitigation will also be presented.

Developing the IEA Reading Literacy Tests

Abstract The International Association for the Evaluation of Educational Achievement (IEA) reading literacy tests were developed co‐operatively to measure the reading ability of 9 and 14 year‐old students in 32 school systems. Test items covered three domains — Narrative, Expository and Documents — and a range of mental processes and themes. An international steering committee screened and modified test materials submitted by participating countries according to agreed guidelines. Extensive editing and rating was done by national representatives to minimise potential cultural bias. After careful translation of materials pilot tests were conducted in most school systems, and analyses conducted to identify poor fitting items to an international Rasch scale. Concurrent studies were conducted on issues of item format and test layout. Final test materials were selected co‐operatively on psychometric, cultural and content criteria and showed acceptable reliability and comparability across nations.

Test chip based approach to automated diagnosis of CMOS yield problems

The authors describe a design approach for, and experimental results obtained from, a test chip developed for the purpose of automated diagnosis of random-defect-dominated yield problems of CMOS ICs. Unlike test chips comprised of ad hoc collections of test structures, the test chip described here is based on the notion of systematic structural decomposition, employed to ensure complete sets of structures required for unambiguous identification of all structural features associated with electrical faults. Test structure selection, sizing, layout, testing, and data analysis are discussed, and examples of rejected wafers are presented to illustrate the direct and straightforward way in which unambiguous diagnosis are obtained. Conclusions related to implementation of an expert system for automated CMOS process problem diagnosis employing the data obtained from this test chip are summarized.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Effects of wavefront aberration on visual instrument performance, and a consequential test technique

Assessment of the visual image quality produced by afocal optical systems is complicated, by both the coherent coupling between eye and instrument and the general lack of correlation between the modulation transfer function and visual performance. This paper summarizes previous results obtained by the authors on simulating primary wavefront aberrations and extends the results to more typical higher-order aberrations, using the same image processor as before. The results strongly support the adoption of a form of Strehl ratio measurement as an outstandingly simple, yet visually appropriate assessment method for afocal systems. A possible test layout is suggested.

Universal power and cavitation stand for testing hydraulic turbines and reversible pump-turbine motor-generator units

The power and cavitation stand of KhTZ is a universal device for testing model hydraulic turbines and reversible pump-turbine units of various types. The design of the stand, its power equipment, and measuring devices permit conducting comprehensive tests of models in a wide range of heads, right up to those close to the prototype. The introduction, on the stand, of a system for automatic control and stabilization of the test regimes and method of measuring regime parameters by means of the measuring and computing complex made it possible to reduce by about half the measurement errors and to raise the accuracy of the tests to the level attained at the best Soviet and foreign laboratories. On the whole, the values and stability of the test regime parameters, dimensions and layout of the models, and the measurement and test methods used on the stand correspond to the IEC recommendations and standards.

Visualilisation hydrodynamique de l'écoulement dans une maquette de turbomachine axiale

To enhance the knowledge of the penomena characterising flow in an axial turbomachine, visual inspection in a hydrodynamic tunnel was performed by the ONERA, drawing the existing analogy between aerodynamic and hydraulic flow conditions. The visual scrutiny of walls and space is obviously easier and finer in water than in air, especially in non-stationary state. The scale-model used is vertical and includes a mobile runner fitted with 20 cylindrical vanes (circumference 1 = 50 mm) placed in a cylindrical channel (radius of casing R = 146 mm). As the flow velocity V1 and the speed of rotation N of the runner are controlled and regulated independently, all operating conditions can be simulated using this assembly. In addition to the main testing layout (isolated mobile runner), a few variations have also been tested (mobile runner with a rectifier, mobile runner with a rotating keel). The assembly has been designed to the used for the following scanning methods : - emissions of a coloring agent of density 1 produced from fixed or mobile elements (carcen, hub, vanes, etc.) - air bubles in suspension in the water. They are observed through lit sections placed logitudinally (diametrically cut or half-way up the vanes) or transversally (cut at the edge of leakage of mobile vanes or half-way along the chord of the rectifier blades). The power and efficiency of the stage are a function of the volume flow and the percentage by comparison with optimum power due to ventilation. The transition zone between motor and receiver modes of the stage is approximately (QV)* = 0.5. Maximum power intake is a major share of optimum power, especially when the variation of (Q V)* is associated with an increase in downstream pressure. The hypotheses adopted and the analytical findings are in agreement with experience and yield an acceptable accurate forecast of the performance of a turbine stage under partial load. The conclusion from the various observations made is that terminal stage flow is highly sensitive to the load variations necessitated by its environment. A separated flow rotating en bloc with the mobile blading occurs at the downstream section of the blade when the volume flow is reduced to 25 % below its rated value. The stall then increases and forces the flow to the central part and the periphery up to the point at which a second toric vortex is formed upstream and at the tip of the blade. This eddy rotates at virtually the same speed as the mobile blading. At zero flow, the two eddies rotating in opposite directions invade the channel and produce called losses due to ventilation, in which the centrigual effect is dominant.

Process Control Panel Design and Construction in the Seventies

The accent on centralised control has led to a considerable reduction in panel length by the use of high density instrumentation. Condensing the panel length introduces the problem of mounting back of panel equipment in a much reduced area. Several designs of control panels have been developed within the process industry and the paper reviews the various answers to this problem. One particularly successful integrated design is described and includes development, layout, fabrication, shop testing, transport, installation, maintenance and control house layout. The paper concludes with various improvements and innovations for the future and the impact of integrated panel design on manufacturers and users.

Field Checks of the Salt-Velocity Method

Abstract This paper gives the results of some tests made in Brazil on which verification of the reliability of the salt-velocity method of measuring discharge was obtained by cross checks with the method itself, by check tests with the Gibson pressure-time method, and by volumetric tests. These show a highly satisfactory agreement even in setups where the testing layout was far from ideal.

Apparatus for long period temperature - stress tests on metals

The paper describes an apparatus for high temperature mechanical testing suitable for accurate determination of creep and allied effects. The apparatus includes a sensitive extensometer and a method for very close control of the temperature of the specimen heated in an electric resistance furnace. The method makes use of a platinum resistance coil placed in the furnace, and which forms part of a Wheatstone Bridge and through a control indicator and relay operates the adjustment of the furnace current to compensate for minor fluctuations from various causes. The form of testing machine and layout are described, and the order of sensitivity indicated.