Accuracy Of Indirect Measurement Research Articles

Evaluating methods for measuring the leaf area index of encroaching shrubs in grasslands: From leaves to optical methods, 3-D scanning, and airborne observation

Leaf area index (LAI) is a key variable describing ecosystem structure and influencing the exchange of carbon, water, and energy. LAI is often evaluated with indirect methods. However, the accuracy of indirect measurements can vary with canopy structure and is not always generalizable across ecosystems. Previous research has characterized the accuracy of indirect methods for woody plants in forest ecosystems, but it is not well established for woody plants in open ecosystems—despite having large differences in canopy structure. In this study, we compared direct LAI measurements in clonal grassland shrub canopies to three indirect methods: a ceptometer, a handheld 3D scanner (processed using EXScanPro-3.6 software), and NEON's LAI product obtained from airborne hyperspectral imaging (derived from SAVI). To our knowledge, this is the first study to assess the accuracy of leaf area data in woody plants using a handheld 3D scanner and one of few studies assessing the accuracy of the National Ecological Observation Network's (NEON) Airborne Observation Platform—our source of airborne hyperspectral imaging. Data were collected in tallgrass prairie undergoing woody encroachment and three treatments: no herbivore disturbance, bison present, and simulated browsing. We found that direct LAI measurements of control and grazed C. drummondii canopies averaged ∼8.0. The ceptometer accurately estimated LAI in non-browsed canopies but overestimated LAI of browsed canopies by 38 %. One-sided leaf area of ramets measured with a handheld 3D scanner was strongly related to direct measurements (r2=0.86), but underestimated leaf area at greater values. LAI estimated from airborne spectral data underestimated LAI by 55 %. We conclude that a ceptometer was adequate for measuring LAI in dense shrub canopies when browsing was not present, the handheld 3D scanner was adequate for measuring leaf area of individual ramets, and the airborne spectral data was not suitable for estimating LAI of dense, grassland shrub canopies.

An intra-individual approach for detecting evaluation with event-related potentials

The P3-based concealed information test (CIT) is an accurate indirect measure of non-evaluative memories (e.g., knowledge of an incriminating item). Less clear and established, however, is the accuracy of indirect measures that rely on the P3-like late positive potentials (LPPs) in discriminating evaluative (e.g., pleasant or unpleasant) memories. Using an LPP-based evaluative oddball paradigm in which participants were truthful on half of the trials about their evaluation toward pictures and concealed their evaluation on the other half of trials toward pictures, we applied an intra-individual Bayesian scheme to classify whether participants' evaluations were congruent or incongruent with a preceding context. LPPs were predictably larger to evaluatively incongruent than congruent pictures, and this LPP effect was reduced during misreporting presumably because of enhanced cognitive load. Notably, across two experiments the sensitivity (80%) was respectable during truth telling, but poor during concealment (sensitivity = 35%). Taken together, these data suggest that indirect measures such as the LPP-based evaluative oddball may be useful for detecting individual evaluation, but more work is warranted that explores conditions under which concealment of evaluation may be more accurately assessed.

Choosing the Optimal Ratio of Flowmeter Errors to Improve the Accuracy of Indirect Measurements of the Difference in Flow Rates

We investigate the possibility of increasing the accuracy of indirect measurements of the difference in the flow rates in a thermal carrier as a result of the choice of flowmeters whose errors are in a certain ratio. Recommendations for choosing the optimal ratio of flowmeter errors are given.

Analysis of the error of the developed method of determination the active conductivity reducing the insulation level between one phase of the network and ground, and insulation parameters in a non-symmetric network with isolated neutral with voltage above 1000 V

In the work the study of the developed method was carried out for reliability by analyzing the error in indirect determination of the insulation parameters in an asymmetric network with an isolated neutral voltage above 1000 V. The conducted studies of the random relative mean square errors show that the accuracy of indirect measurements in the developed method can be effectively regulated not only by selecting a capacitive additional conductivity, which are connected between phases of the electrical network and the ground, but also by the selection of measuring instruments according to the accuracy class. When choosing meters with accuracy class of 0.5 with the correct selection of capacitive additional conductivity that are connected between the phases of the electrical network and the ground, the errors in measuring the insulation parameters will not exceed 10%.

The deterministic grey dynamic model with convolution integral DGDMC(1, n)

Although the grey forecasting models have been successfully utilized in many fields and demonstrated promising results, literatures show their performance still could be improved. The grey prediction theory is methodology and it is necessary to constantly present new models or algorithm based on the theory to improve its performance, prediction accuracy especially. For this purpose, this paper proposes a new prediction model called the deterministic grey dynamic model with convolution integral, abbreviated as DGDMC(1, n). Improvements upon the existing grey prediction model GM(1, n) are made to a large extent and the messages for a system can be inserted sufficiently. The major improvements include determining the unbiased estimates of the system parameters by the deterministic convergence scheme, introducing the first derivative of the 1-AGO data of each associated series into the DGDMC(1, n) model to strengthen the indicative significance and evaluating the modelling 1-AGO data of the predicted series by the convolution integral. The indirect measurement of the tensile strength of a material for a higher temperature is adpoted for demonstration. The results show that the accuracy of indirect measurement is higher by the DGDMC(1, n) model than by the existing GM(1, n) model.

Accuracy of Indirect Measurement of Blood Pressure in Neonatal Foals

Accuracy of Indirect Measurement of Blood Pressure in Neonatal Foals

The indirect measurement of tensile strength by the deterministic grey dynamic model DGDM(1, 1, 1)

This paper studies the dynamic relationship between hardness and tensile strength of a material, through which we evaluate the tensile strength of the material for a higher temperature from the corresponding experimental data of Brinell hardness. The tensile strength of a material based on temperature is important for mechanical engineering design. It is harder and takes more time to obtain experimental data of the tensile strength than to obtain those data of the Brinell hardness of a material. The prediction model DGDM( 1, 1, I) is employed in this study. The series of Brinell hardness at equispaced intervals of temperature is considered as the leading indicator ( the input series) while the series of tensile strength of the material at the corresponding temperature is taken as the output series. The result shows that the tensile strength and the Brinell hardness of a material are highly correlated and the accuracy of indirect measurement of the tensile strength is satisfactory.

Minimization of error in indirect measurements

We pose the problem of minimizing the error in indirect measurements; the solution of this problem reduces to nonlinear programming. Under certain conditions, the results we obtain make it possible to increase the accuracy of indirect measurements, to design measuring systems with controlled minimal measurement error, and to control the distribution of resources in order to minimize error.

Statement on hypertension in the elderly. The Working Group on Hypertension in the Elderly

Research indicates that isolated systolic hypertension, as well as diastolic hypertension, is associated with increased morbidity and mortality in people over age 65. According to data from the 1976 to 1980 National Health and Nutrition Examination Survey, the prevalence of these combined types of hypertension (greater than or equal to 140/90 mm Hg) is estimated to be 64% in persons aged 65 to 74 years, with an even higher prevalence in blacks (76%) than in whites (63%). Although a number of studies have demonstrated the benefits of antihypertensive therapy in elderly patients, many questions unique to this population remain unanswered. This article addresses several of these issues and presents recommended guidelines on topics such as the pressure at which treatment should be initiated, goal pressure for people over age 65, antihypertensive drugs of choice and appropriate dosages, the accuracy of indirect measurements, side effects specific to elderly patients, and the effect of treatment on the quality of life.

Accuracy of indirect measurements involving multiplication and discrete integration

Accuracy of indirect measurements involving multiplication and discrete integration