scholarly journals Comparing Two Diagnostic Processes: Operating Characteristics of Nonparametric Methods

2013 ◽  
Vol 61 (1) ◽  
pp. 131-138
Author(s):  
Md. Akhtar Hossain ◽  
Nahid Sultana Sumi
Keyword(s):  
Simulation Study ◽  
Roc Curves ◽  
Nonparametric Test ◽  
Nonparametric Methods ◽  
Test Methods ◽  
Operating Characteristics ◽  
Extensive Simulation ◽  
Wide Range ◽  
Area Under Roc Curve ◽  
And Performance

The area under ROC curve (AUC) is frequently used as a measure for the effectiveness of diagnostic processes. The aim of this paper is to explore and evaluate several nonparametric test methods of comparing the effectiveness and performance of two competing diagnostic processes producing quantitative ratings. These nonparametric methods make use of ROC curves when comparing the diagnostics processes. An extensive simulation study is performed to investigate the operating characteristics of the test methods in a wide range of settings. Dhaka Univ. J. Sci. 61(1): 131-138, 2013 (January) DOI: http://dx.doi.org/10.3329/dujs.v61i1.15114

The Use of ASM based Models for the Simulation of Biological Sludge Reduction Processes

2008 ◽  
Vol 3 (3) ◽  
Author(s):  
Bruce R. Johnson ◽  
Glen T. Daigger ◽  
John T. Novak
Keyword(s):  
Wastewater Treatment ◽  
Research Effort ◽  
Reduction Process ◽  
Decay Product ◽  
Sludge Reduction ◽  
Operating Characteristics ◽  
Biological Sludge ◽  
Wide Range ◽  
Treatment Facilities ◽  
And Performance

The advent of sludge reduction technologies that are capable of significantly reducing sludge production from wastewater treatment facilities has garnered much interest from the wastewater treatment profession. As part of CH2M HILL's effort to better understand the mechanisms behind these processes, a research effort was completed that was focused on developing an ASM based model which adequately reflects the performance of the Cannibal® Sludge Reduction process by Siemens. A modification is proposed of the standard ASM 2d model to capture the effects of biological sludge reduction used in the Cannibal Solids Reduction process. This model is able to capture the essential aspects of this system and provides a more quantitative method for the sizing and performance of these types of systems. The primary components of this modification include separation of the microbiological decay products from the traditional particulate inert fraction, and into a separate particulate decay product for aerobic/anoxic microbes (XDAA). A new process rate is included in the model for anaerobic “hydrolysis” of XDAA to XS. The results were compared against the experience of Siemens on a wide range conditions. The results indicate that this model predicts operating characteristics of the Cannibal process with a reasonable level of accuracy.

scholarly journals The design and performance on 200N-class bipropellant rocket engine using decomposed H2O2 and Kerosene

2019 ◽  
Vol 11 (3) ◽  
pp. 99-110
Author(s):  
Yang-Suk LEE ◽  
Jun Hwan JANG
Keyword(s):  
Hydrogen Peroxide ◽  
Rocket Engine ◽  
Test Methods ◽  
Liquid Rocket Engine ◽  
Flow Test ◽  
Wide Range ◽  
Green Propellant ◽  
And Performance ◽  
Liquid Rocket ◽  
Near Future

Mono-propellant thrusters are widely utilized in satellites and space launchers. In many cases, they are using hydrazine as a propellant. However, hydrazine has high toxicity and high risks in using for launch campaign. Recently, low-toxic (green) propellant is being highlighted as a replacement for hydrazine. In this paper, 200N bi-propellant engine using hydrogen peroxide/kerosene was designed/manufactured, and the spray or atomization characteristic and inflation pressure were determined by cold flow test, and combustion and pulse tests in a single cycle same as previous methods were conducted. As uniformly supplying hydrogen peroxide through plate-type orifice to a catalyst bed, the hot gas was created as a reaction with hydrogen and catalyst. And then, it was confirmed that the ignition is possible on the wide range of O/F ratio without additional ignition source. The liquid rocket engine with bi-propellant of hydrogen peroxide/kerosene and design/test methods which developed in this study are expected to be utilized as an essential database for designing of the ignitor/injector of bi-propellant liquid rocket engine using hydrogen peroxide/kerosene with high-thrust/performance in near future.

scholarly journals Accuracy of Subclinical Ketosis Detection with Rapid Test Methods for BHBA in Blood in Commercial Dairy Farms

Dairy ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 671-683
Author(s):  
Henrike Jansen ◽  
Marleen Zschiesche ◽  
Dirk Albers ◽  
Wilhelm Wemheuer ◽  
A. Sharifi ◽  
...  
Keyword(s):  
Blood Serum ◽  
Rapid Test ◽  
Reference Method ◽  
Dairy Farms ◽  
Test Methods ◽  
Operating Characteristics ◽  
Negative Effects ◽  
Subclinical Ketosis ◽  
Receiver Operating Characteristics Curve ◽  
And Performance

This study gives an overview of the performance and accuracy of devices used for the fast measurement of β-hydroxybutyrate (BHBA) in blood for the on-farm indication of subclinical ketosis. Data were collected on ten dairy farms. In each farm, blood samples were taken from ten cows on four test days (2, 4, 9 and 11), resulting in 400 samples. The reference method was the BHBA concentration in blood serum (BHBALAB). Four different devices that measure BHBA in whole blood were tested. The thresholds applied for identifying subclinical ketosis were ≥1.0, ≥1.2 and ≥1.4 mmol/L in blood serum. The BHBALAB was assigned in three classes: low—≤0.9 mmol/L; high—>0.9 mmol/L; and total—all values unclassified. Due to initial negative effects on the health and performance of cows with BHBA levels ≥0.9 mmol/L, this cut-off was chosen. The Passing–Bablok regression revealed different constant as well as absolute biases for each device in the aforementioned classes. The area under the receiver operating characteristics curve indicated highly accurate results, with 94–97% accuracy levels. As an overall conclusion, the performance of the devices was good and supports their use by farmers for the detection of subclinical ketotic cows in their herds.

scholarly journals A Guide for Sparse PCA: Model Comparison and Applications

Psychometrika ◽  
2021 ◽  
Author(s):  
Rosember Guerra-Urzola ◽  
Katrijn Van Deun ◽  
Juan C. Vera ◽  
Klaas Sijtsma
Keyword(s):  
Performance Measures ◽  
Simulation Study ◽  
Empirical Data ◽  
Population Model ◽  
Model Comparison ◽  
Optimization Criterion ◽  
Sparse Pca ◽  
Extensive Simulation ◽  
Explained Variance ◽  
And Performance

AbstractPCA is a popular tool for exploring and summarizing multivariate data, especially those consisting of many variables. PCA, however, is often not simple to interpret, as the components are a linear combination of the variables. To address this issue, numerous methods have been proposed to sparsify the nonzero coefficients in the components, including rotation-thresholding methods and, more recently, PCA methods subject to sparsity inducing penalties or constraints. Here, we offer guidelines on how to choose among the different sparse PCA methods. Current literature misses clear guidance on the properties and performance of the different sparse PCA methods, often relying on the misconception that the equivalence of the formulations for ordinary PCA also holds for sparse PCA. To guide potential users of sparse PCA methods, we first discuss several popular sparse PCA methods in terms of where the sparseness is imposed on the loadings or on the weights, assumed model, and optimization criterion used to impose sparseness. Second, using an extensive simulation study, we assess each of these methods by means of performance measures such as squared relative error, misidentification rate, and percentage of explained variance for several data generating models and conditions for the population model. Finally, two examples using empirical data are considered.

Conscious access to fear-relevant information is mediated by threshold

2011 ◽  
Vol 42 (2) ◽  
pp. 56-64 ◽  
Author(s):  
Remigiusz Szczepanowski
Keyword(s):  
Present Report ◽  
Intrinsic Property ◽  
Roc Curves ◽  
Relevant Information ◽  
Perceptual Processing ◽  
High Threshold ◽  
Operating Characteristics ◽  
Emotional Perception ◽  
Fearful Faces ◽  
The Subject

Conscious access to fear-relevant information is mediated by thresholdThe present report proposed a model of access consciousness to fear-relevant information according to which there is a threshold for emotional perception beyond that the subject makes hits with no false alarm. The model was examined by having the participants performed a confidence-ratings masking task with fearful faces. Measures of the thresholds for conscious access were taken by looking at the receiver operating characteristics (ROC) curves generated from a three-state low- and high-threshold (3-LHT) model by Krantz. Indeed, the analysis of the masking data revealed that the ROCs had threshold-like-nature (a two-limb shape) rather continuous (a curvilinear shape) challenging in this fashion the classical signal-detection view on perceptual processing. Moreover, the threshold ROC curve exhibited the specific y-intercepts relevant to conscious access performance. The study suggests that the threshold can be an intrinsic property of conscious access, mediating emotional contents between perceptual states and consciousness.

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