Relevant Test Parameters Research Articles

Critical LME elongation: a criterion measured with Gleeble correlated to LME sensitivity during spot welding

Liquid metal embrittlement may appear on multiphase high strength galvanized steels during the spot-welding process. The aim of this paper is to describe a high temperature tensile test, performed with a Gleeble machine, to evaluate the LME sensitivity of a given coated steel in conditions similar to spot welding (time cycle). The critical LME elongation, corresponding to minimum of stress derivative during force decrease, has been found as being the most relevant parameter to measure the LME phenomenon. Relevant test parameters such as temperature, strain rate, applied thermal cycle, and effect of thermocouple welding have been studied on two steels. The first, TRIP 800 steel, presents a high sensitivity to LME between 750 °C and 900 °C while the second, DP600 steel, is not sensitive. Strain rate effect reveals a competition between LME crack propagation and ductile fracture. The study also shows the need to avoid welding thermocouple on Zn-coated side. Overall, the critical LME elongation from Gleeble test is well correlated to LME cracks number and depth in spot welding.

Applications of Machine Learning Methods to Predict Hole Cleaning in Horizontal and Highly Deviated Wells

Summary Machine learning (ML) has become a robust method for modeling field operations based on measurements. For example, wellbore cleanout is a critical operation that needs to be optimized to enhance the removal of solids to reduce problems associated with poor hole cleaning. However, as wellbore geometry becomes more complicated, predicting the cleaning performance of fluids becomes more challenging. As a result, optimization is often difficult. Therefore, this research focuses on developing a data-driven model for predicting hole cleaning in deviated wells to optimize drilling performance. More than 500 flow loop measurements from eight studies are used to formulate a suitable ML model to forecast hole cleanout in directional wells. Measurements were obtained from hole-cleaning experiments that were conducted using different loop configurations. Experiments ranged in test-section length from 22 to 100 ft, in hole diameter from 4 to 8 in., and in pipe diameter from 2 to 4.5 in. The experiments provided measured equilibrium bed height at a specific flow rate for various fluids, including water-based and synthetic-based fluids and fluids containing fibers. Several relevant test parameters, including fluid and cutting properties, well inclination, and drillstring rotation speed (drillpipe rev/min), were also considered in the analysis. The collected data have been analyzed using the Cross-Industry Standard Process for Data Mining. This paper is unique because it systematically evaluates various ML models for their ability to describe hole cleanout processes. Six different ML techniques: boosted decision tree (BDT), random forest (RF), linear regression, multivariate adaptive regression spline (MARS), neural networks, and support vector machine (SVM) have been evaluated to select the most appropriate method for predicting bed thickness in a wellbore. Also, we compared the predictions of the selected ML method with those of a mechanistic model for cases without drillstring rotation. Finally, using the ML model, a parametric study has been conducted to examine the impact of various parameters on the cleanout performance of selected fluids. The results show the relative influence of different variables on the prediction of cuttings bed. Accordingly, flow rate, drillpipe rev/min, and fluid behavior index have a strong impact on dimensionless bed thickness, while other parameters such as fluid consistency index, solids density and diameter, fiber concentration, and well inclination angle have a moderate effect. The BDT algorithm has provided the most accurate prediction with an R2 of 92%, a root-mean-square error (RMSE) of 0.06, and a mean absolute error (MAE) of roughly 0.05. A comparison between a mechanistic model and the selected ML technique shows that the ML model provided better predictions.

Label-free detection and identification of single bacteria via terahertz near-field imaging.

In recent years, terahertz (THz) imaging has attracted much attention because of its ability to obtain physical and chemical information in a label-free, noninvasive and nonionizing manner. However, the low spatial resolution of traditional THz imaging systems and the weak dielectric response of biological samples hinder the application of this technology in the biomedical field. In this paper, we report a new THz near-field imaging method for a single bacteria, through the coupling effect of nanoscale radius of probe and platinum gold substrate, which greatly enhances THz near-field signal of biological samples. A THz super-resolution image of bacteria has been successfully obtained by strictly controlling the relevant test parameters such as tip parameters and driving amplitude. By analyzing and processing the THz spectral image, the morphology and inner structure of bacteria have been observed. The method has been used to detect and identify Escherichia coli represented by Gram-negative bacteria and Staphylococcus aureus represented by Gram-positive bacteria. This application provides a new label-free, noninvasive and nonionizing testing protocol for the detection of single bacteria.

Controller Design of a Brake-By-Wire System Based on Giant-Magnetostrictive Material for an Intelligent Vehicle

Mechatronics control technology can not only improve the performance of vehicles but also solve traditional automotive braking system problems such as long brake pipeline, lots of valve components, slow response and so on. In this paper, a giant-magnetostrictive actuator and a disc brake structure were used to build a drive control system, and the control system module was designed with a single-chip microcomputer as the core. Combined with sensor selection, software programming control was used to build the experimental test platform, and the maximum output displacement of the control system was 0.112156 mm, which was basically consistent with the theoretical calculation. The maximum output force was 3883 N, which exceeded the minimum output force of 3631 N calculated theoretically. According to the results of the test platform, the relevant test parameters were highly consistent with the theoretical calculation, which verified the correctness and effectiveness of the theoretical calculation and bench testbed design. It contributes to the improvement of vehicle active safety performance and can provide a new way for the development of an intelligent vehicle brake-by-wire system.

Mechanical Performance Test and Numerical Simulation Analysis of Building Steel Plate and Concrete Composite Structure.

The study aims to continuously improve the level of the construction industry, such as the improvement of construction capacity and efficiency and reduction of the project cost and construction period, and find a specific way to improve the development of the construction industry. First, the study analyzes the research status of mechanical properties of horizontal joints, vertical joints, and the overall structure of worldwide prefabricated buildings. Next, the built-in steel fabricated concrete shear wall model is established. Moreover, the quasi-static experimental analysis is conducted on the joints of the fabricated shear wall with built-in section steel. The finite element software is used to analyze the numerical simulation test of the new built-in shear wall. According to the relevant test parameters, the finite element model is constructed, and the parameters are set. Finally, the shear wall model is established and tested by a simulation experiment, and the simulation results are compared with the numerical simulation results. The final results show that the proposed connection mode of the reinforced skeleton and new fabricated joints improves the stability of prefabricated buildings. The use of the quasi-static test to test the relevant performance parameters has a short calculation time, high efficiency, and high parameter optimization accuracy. It can better simulate the actual working conditions and the actual stress-strain and damage failure conditions. Moreover, the conclusion is drawn that the shear wall structure with steel plate concrete has good ductility and deformation capacity. The study has a certain reference significance for the construction optimization of steel plate concrete prefabricated buildings and related research in the future.

Experimental and Numerical Results of LIFUS5/Mod3 Series E Test on In-Box LOCA Transient for WCLL-BB

The in-box LOCA (Loss of Coolant Accident) represents a major safety concern to be addressed in the design of the WCLL-BB (water-cooled lead-lithium breeding blanket). Research activities are ongoing to master the phenomena and processes that occur during the postulated accident, to enhance the predictive capability and reliability of numerical tools, and to validate computer models, codes, and procedures for their applications. Following these objectives, ENEA designed and built the new separate effects test facility LIFUS5/Mod3. Two experimental campaigns (Series D and Series E) were executed by injecting water at high pressure into a pool of PbLi in WCLL-BB-relevant parameter ranges. The obtained experimental data were used to check the capabilities of the RELAP5 system code to reproduce the pressure transient of a water system, to validate the chemical model of PbLi/water reactions implemented in the modified version of SIMMER codes for fusion application, to investigate the dynamic effects of energy release on the structures, and to provide relevant feedback for the follow-up experimental campaigns. This work presents the experimental data and the numerical simulations of Test E4.1. The results of the test are presented and critically discussed. The code simulations highlight that SIMMER code is able to reproduce the phenomena connected to PbLi/water interaction, and the relevant test parameters are in agreement with the acquired experimental signals. Moreover, the results obtained by the first approach to SIMMER-RELAP5 code-coupling demonstrate its capability of and strength for predicting the transient scenario in complex geometries, considering multiple physical phenomena and minimizing the computational cost.

Post-test analysis of Series D experiments in LIFUS5/Mod3 facility for SIMMER code validation of WCLL-BB In-box LOCA

The In-box LOCA for the WCLL-BB is recognized as a Design Basis Accident (DBA) and is of substantial interest to the DEMOnestration reactor design, therefore, the transient response of such an accident must be carefully investigated and addressed to ensure the safe operation and integrity of the whole system. In this way, the LIFUS5/Mod3 test facility (constructed at ENEA Brasimone Research Center) has been upgraded in the period 2018–2020 to perform a series of tests. The first set of the tests were named Series D, which are characterized by injecting specified amounts of pressurized water into the Lithium lead liquid bulk. The experimental campaign aimed at validating and qualifying the SIMMER-III code as a reliable numerical tool for the safety studies of the WCLL BB.In parallel with performing the tests, SIMMER-III Verification and Validation (V&V) was conducted according to a standard code validation procedure. SIMMER-III is a two-dimensional, multiphase, multicomponent, Eulerian, fluid-dynamics code which was firstly developed at the Japan Nuclear Cycle Development Institute (JNC). An adopted version of the original SIMMER-III code so-called Ver.3 F Mod.0.1 (which was developed at University of Pisa), was employed for the analyses. The V&V activity was successfully completed and documented as the technical reports within the past numerical analytical and experimental activities for the first three tests (D1.1, D1.2 and D1.5).In this article, the experimental data of the Tests D1.1, D1.2 and D1.5 are used for the SIMMER-III code results comparison. A qualitative analysis of the results obtained is reported according to the time trends for the most relevant parameters. The results show that the SIMMER-III code acceptably predicts the transient and the accuracies of the relevant test parameters are in agreement with the acquired experimental signals. Although that the primarily validation results are highly promising but further code assessment, development and validation are essential to approach such a qualified system code, which is suitable for fusion safety applications. The present validation work has been successfully followed by its ongoing experimental and numerical activities as a multilateral EUROfusion project.

Energy Saving Technology of 5G Base Station Based on Internet of Things Collaborative Control

For time and space constraints, 5G base stations will have more serious energy consumption problems in some time periods, so it needs corresponding sleep strategies to reduce energy consumption. Based on the analysis of 5G super dense base station network structure, through the analysis of current situation and user demand, a cluster sleep method based on genetic algorithm is constructed under the support of genetic algorithm, which can realize the dynamic matching of energy consumption in time domain and space, and the low load base station enters the sleep state. In order to verify the performance of the algorithm, the simulation network structure is built on the MATLAB platform, and the advantages of the algorithm in this study are obtained through comparative analysis, and the relevant test parameters are set for the technical performance analysis of this study. The research shows that the method proposed in this paper has a certain energy-saving effect, can meet the energy efficiency requirements of 5G ultra dense base station, and in the ultra dense base station group, the complexity can also meet the system operation requirements, which has a certain degree of practicality, and can provide reference for the follow-up related research.

Simulator Study of MOM using Steep-cup Flexion - A Clinically Relevant Incorporation of Intermittent Edge-loading

Background: Adverse-wear phenomenon in metal-on-metal (MOM) arthroplasty has been attributed to “edge-loading” of the CoCr cups. Simulator studies of steeply-inclined cups run in the ‘Anatomic-cup’ model represented many variations in design and test parameters with no coherent rationale. We created an algorithm to synthesize MOM test parameters and noted that wear areas typically averaged only 10-15% of cup surface. In contrast, retrievals showed wear areas extending to 60% of cup surface. We hypothesized that MOM wear studies run in the orbital hip simulator with the ‘Inverted-cup’ model would, (i) differentiate normal-loading versus edge-loading, (ii) demonstrate cup wear areas x3.8-times larger than on femoral heads, cover 30% of cup surface, and (iii) double the wear-rates measured in prior Anatomic-cup study.Methods: Edge-loading occurs when the cup rim is allowed to truncate the habitual wear area that provides optimal tribological conditions. A MOM algorithm was developed to synthesize relevant test parameters. The 60mm MOM bearings donated for this study were run in an orbital hip simulator using the Inverted-cup model. Tests #1 and #2 to one million cycles (1-Mc) duration assessed wear at peak cup inclinations 40° and 50°. Test #3 evaluated edge-loading with peak cup inclinations achieving 70° (5-Mc duration).Results: Wear areas in Inverted-cups averaged 1663mm2 in tests #1 and 2, were fully contained within cup rims, and covered 30% of cup surface as predicted by algorithm. Test-3 with 70° cup inclination produced the predicted edge-loading with volumetric wear-rates averaging 2mm3/Mc, approximately 5-fold greater wear than prior Anatomic-cup study.Discussion and Conclusions: Simulator studies of steep-cup mechanisms necessitate production of clinically-relevant wear-patterns such that the biomechanical and tribological functionality is respected. As an aid to steeply-inclined cup analyses, the MOM algorithm allowed integration of confounding test parameters. The algorithm successfully differentiated between “normal” and “edge loaded” cups and the MOM wear areas were as predicted for three cup inclinations. Also as predicted, wear-patterns in Inverted-cup model exactly reversed those of the Anatomic-cup model. Even with only intermittent edge-loading, Test-3 produced 5-fold greater wear than our prior Anatomic study.Clinical Significance: The Inverted-cup simulator model successfully mobilized the cup to produce larger wear areas that were more representative of those in-vivo and therefore reproduced more realistic test conditions for studies of edge-loaded cups.

Identifying representative test parameters to assess skin laceration injury risk for individual studs

Skin injuries account for ∼6% of all injuries in rugby union. Skin lacerations resulting from stud–skin interactions in rugby union are frequently caused by stamping in the ruck (Oudshoorn, Driscoll, Dunn, & James, 2016 Oudshoorn, B. Y., Driscoll, H. F., Dunn, M., & James, D. (2016). Procedia Engineering, 147, 496–500. [CrossRef], [Google Scholar] ). Stud design is regulated by World Rugby's Regulation 12, but no supporting evidence currently exists for the selected test parameters used in these standards. Ideally, mechanical tests that assess injury risk should replicate conditions observed during play (Ura & Carre, 2016 Ura, D., & Carre, M. (2016). Procedia Engineering, 147, 550–555. [CrossRef], [Google Scholar] ). Relevant mechanical test parameters, such as foot inbound velocity, stud impact energy, inclination angle and effective mass, can be derived through biomechanical analysis of rugby stamping. However, due to human movement variability, the measured kinetics and kinematics of stamping impacts can have a large range and replicating all possible parameters within a mechanical test device is unfeasible. Identifying different stamp techniques by clustering provides an economical solution.

New bone post-processing tools in forensic imaging: a multi-reader feasibility study to evaluate detection time and diagnostic accuracy in rib fracture assessment

The aim of this multi-reader feasibility study was to evaluate new post-processing CT imaging tools in rib fracture assessment of forensic cases by analyzing detection time and diagnostic accuracy. Thirty autopsy cases (20 with and 10 without rib fractures in autopsy) were randomly selected and included in this study. All cases received a native whole body CT scan prior to the autopsy procedure, which included dissection and careful evaluation of each rib. In addition to standard transverse sections (modality A), CT images were subjected to a reconstruction algorithm to compute axial labelling of the ribs (modality B) as well as "unfolding" visualizations of the rib cage (modality C, "eagle tool"). Three radiologists with different clinical and forensic experience who were blinded to autopsy results evaluated all cases in a random manner of modality and case. Rib fracture assessment of each reader was evaluated compared to autopsy and a CT consensus read as radiologic reference. A detailed evaluation of relevant test parameters revealed a better accordance to the CT consensus read as to the autopsy. Modality C was the significantly quickest rib fracture detection modality despite slightly reduced statistic test parameters compared to modalities A and B. Modern CT post-processing software is able to shorten reading time and to increase sensitivity and specificity compared to standard autopsy alone. The eagle tool as an easy to use tool is suited for an initial rib fracture screening prior to autopsy and can therefore be beneficial for forensic pathologists.

Evaluation on high-temperature adhesion performance of hot-applied sealant for asphalt pavement

In order to investigate the high-temperature performances of the asphalt pavement hot-applied sealant, as well as to reduce failures of the sealant pullout, the softening point test and the flow test (two existing methods for evaluating high-temperature performances) were conducted. It was found that both tests could not accurately reflect the adhesion performances of the sealant at high temperatures. For this purpose, the adhesion test for PSAT (pressure sensitive adhesive tape) has been taken as a reference to develop a device that is suitable for evaluating the adhesion performances, by modifying relevant test parameters according to the road conditions at high temperatures. Thirteen common sealants were tested in the modified adhesion test, softening point test and flow test. The experimental results show that no significant correlation (p>0.05) exists between the adhesion value, softening point, adhesion value and flow value; while a significant correlation (p<0.05) exists between the softening point and flow value. The modified adhesion test is efficient in distinguishing the high-temperature adhesion performances of different sealants, and can be used as a standard method for evaluating such performances.

Numerical Simulation Study on Slaking Deformation Properties of High Earth Core Dam

The initial soaking of coarse-grained soil will trigger significant slaking deformation of this material. In order to study the slaking deformation of a certain dam during impounding process and its impacts on the dam body, we have adopted the slaking constitutive model by singe-line method and relevant test parameters from Changjiang River Scientific Research Institute, and conducted numerical simulation on the whole process from rock filling to impounding and slaking process of high earth core rockfill dam. The result has shown that, after considering slaking deformation of upstream shell materials, the upstream settlement is generally larger than downstream settlement on the same horizontal line, and the settlement of downstream shell materials generally stays unchanged after considering slaking deformation; at the early impounding period, the settlement of dam body is increasing, and the horizontal displacement of upstream side shell materials is pointing towards upstream. These findings can adequately explain the slaking deformation of the dam caused by impoundment, testify the new slaking constitutive model by single-line method and relevant test parameters, and provide reasonable basis for engineering design.

Observation of Mobility Enhancement of Heavy Oils Flowing Through Sand Pack Under Solution Gas Drive

Abstract In situ formation of foamy oils under solution gas drive has been proposed as one of the possible mechanisms responsible for high primary production rate from some heavy oil reservoirs. Maini et al.(7) reported some results from steady-state tests of two methane-saturated heavy oils flowing through a sand pack. They concluded that there was no evidence of the presence of nucleated gas bubbles enhancing the mobility of the heavy oil; rather the oil mobility being decreased due to gas entrapment. This paper is the re-interpretation of their test results through matching both the oil production and the pressure distribution data with a foamy oil viscosity model. It is found that entrapment of gas bubbles in oil would reduce the oil mobility; however, the nucleation of gas bubbles at the grain surface would enhance the mobility. The mobility of the heavy oil increases proportionally with the nucleation rate; but decreases with foam quality following Roscoe's viscosity model(13). A new mobility correlation with the nucleation rate and the foam quality is proposed. With the new correlation, we succeeded in matching both the production rates and the pressure profiles. The mobility enhancement due to the bubble nucleation can be explained by gas lubrication effects. Introduction Anomalously high primary production rates have been experienced by some solution gas drive heavy oil reservoirs in Alberta and Saskatchewan(1–4). The performances of these reservoirs could not be predicted by a Darcy flow model with measured reservoir and fluid properties. To match field performance, the mobilities of oil and gas had to be greatly increased and decreased, respectively, and trapped gas saturations as high as 35% needed(1,2). Based on the numerical simulations of single-phase radial flow to a well, the primary production rate behaviour resembles a dilatant non- Newtonian fluid flow(5). To explain the high primary production rates and recovery factors in heavy oil reservoirs, a number of potential mechanisms have been proposed(1,2, 6–9). One of the possible causes for the anomalous behaviour is the in situ formation of bubbly (or foamy) oil due to entrapment of a large number of microbubbles nucleated during pressure drawdown(10). Evidence of formation of foamy oils was observed in both well head samples and laboratory tests(1,7). The in situ formation of foamy oil can greatly alter the flow behaviours of oil and gas in a reservoir byenhancing oil mobility with gas bubble nucleation;preventing rapid depletion of reservoir energy through retardation of free gas flow; andchanging oil properties due to gas bubble dispersion. The Effect of Bubble Nucleation on Oil Mobility Results of Steady-state Tests To study the effect of gas bubble nucleation on oil mobility, Maini et al.(7) conducted a series of in situ generated foamy oil flow tests in a sand-pack under steady-state conditions. A two metre long sand-pack holder with five equally spaced intermediate pressure taps was used. Tests were done on heavy oils from the Lindbergh and Lloydminster reservoirs. Relevant test parameters and the properties of two oils were presented in their paper.

In vitro Methods for the Assessment of Primary Local Effects of Topically Applied Preparations

Three 'alternative' methods for the screening of the primary irritation potentials of topically applied preparations and raw materials are presented as a test battery and their in vitro endpoints are compared with in vivo data. The first method is the intermediate test on the chorioallantoic membrane of hens' fertilized eggs, which is generally proposed for the prediction of the irritation potential of chemicals. Relevant test parameters, such as the time-dependent appearance of hemorrhages, vascular lysis and coagulation, are used to classify the test substances. Secondly, cytotoxicity tests with Balb/c 3T3 fibroblasts are used to characterize the influence of test materials on cellular homeostasis and viability, which is quantified by the dose-dependent uptake of Neutral red. As a second parameter changes in the cellular protein level can be easily measured by subsequent staining with Kenacid blue. Finally, the third approach to in vitro evaluation is presented in the form of the red blood cell assay, a rapid photometric assay which permits distinguishing basically between damage to the membrane and to proteins as endpoints which correlate with lesions observed on the conjunctiva, iris and cornea in the eye and the acute inflammatory responses evoked during epicutaneous irritancy testing. Changes in the optical behavior of oxyhemoglobin are used as the inherent indicator for monitoring both endpoints and their interrelations. These methods are proposed and can be used advantageously for testing newly developed topical preparations and their ingredients in view of their local irritation potential without further use of animal testing. Moreover, they can also be used for screening chemicals.

Cortisol reactivity and cognitive performance in a continuous mental task paradigm

The after-effects of fatigue or stress on the performance of cognitive tests have been particularly difficult to demonstrate. In this study we examined whether salivary cortisol, used as an index of stress evoked by the continuous performance of mental tasks, reflected individual differences in cognitive performance. In a within-subject experiment in which 24 subjects were exposed to 4 hours of continuous mental activity and to a control session, significantly higher cortisol levels were found during the continuous task session. Cognitive performance was assessed before and after each session. The relevant test parameters involved aspects of verbal memory, concept shifting and divided attention. When subjects were divided into two groups based on the magnitude of individual cortisol responses to the continuous tasks, it was found that the subgroup with higher cortisol responses decreased in attention compared with their attention after the control session. In contrast, the performance of the subgroup with no or lower cortisol responses did not differ between the two sessions. There was no evidence of similar effects on verbal memory or concept shifting.

Experimental and theoretical investigations of creep buckling on NiCr 22 Co 12 Mo tubes at 950°C

The postulated secondary-side depressurization accident in an HTR plant raises the question of whether creep buckling can occur under external pressure in the tubes of the heat exchangers whose cross sections may be slightly eccentric due to manufactural tolerances. Experimental and theoretical investigations were carried out on the problem of creep buckling. Within the scope of these experiments, tubes made of NiCr 22 Co 12 Mo with different adjusted initial ovalities were exposed to pressures of 35–45 bar at 950°C. The buckling times were measured. Theoretical analyses were carried out using a model conceived by Hoff as well as the Finite Element Method, allowing for the scattering of relevant test parameters. Both methods of computation are suitable for investigating the phenomenon of creep buckling. It was found that the calculated buckling times are affected by great uncertainties taking into account the scatter of influential test parameters. In connection with the accidental stressing in an HTR plant it was confirmed that creep buckling is not a problem of high safety-related relevance.

Effects of an overnight fluid infusion on cognitive functions in preoperative patients.

The results of the present study show that subjects who received an overnight infusion of isotonic fluid did significantly less well at particular neuropsychological tests than controls who did not receive such an infusion. The relevant test parameters involved aspects of word list learning, and concept shifting on a complex speed task. Potentially biasing factors such as anxiety, disturbed sleep, education and age could be discarded. With respect to the physiological mechanism involved, the results suggest that a relatively expanded extracellular volume without dilutional hyponatremia might underlie the diminished performance. The experimental group did not lose weight overnight, and the hemoglobin and haematocrit level of the experimental group were significantly different from those of the control group; the blood pressure, plasma electrolytes and osmolality were not different. The present results provide evidence that disturbances in fluid homeostasis may affect cognitive performance.

Kinetic studies of steam gasification of char in the presence of H 2, CO 2 and CO

Kinetic studies have been carried out to elucidate the mechanisms of steam and CO 2 gasification of char and the interactions of these gasifying agents. The positive and negative influences of all product gases, excluding methane, were considered. An empirical approach was derived to describe the effects of the degree of carbon conversion on the reaction rate as a function of relevant test parameters (pressure range 1–70 bar, temperature 800–1000 °C). To assess the validity of the derived kinetic equation a model of a fluidized-bed gasifier is presented.

Element of Chance and Comparative Reliability of Matching Tests and Multiple-Choice Tests

Simple formulas for the reliability of matching tests and multiple-choice tests, based on the assumption that chance success by guessing is the only source of error variation, are derived. The reliabilities of the two types of tests are compared, and an explicit formula relating their reliability coefficients when relevant test parameters remain fixed is presented. It is found that, in the majority of cases which are likely in practice, matching tests are considerably less fallible than multiple-choice tests.