Model-Based Criteria Heuristics for Second-Phase Spatial Sampling

2012 ◽  
pp. 54-71
Author(s):  
Eric M. Delmelle
Keyword(s):  
Spatial Sampling ◽  
Second Phase ◽  
Model Based

scholarly journals Effects of sample size and model form on the accuracy of model-based estimators of growing stock volume

2015 ◽  
Vol 45 (11) ◽  
pp. 1524-1534 ◽  
Author(s):  
Svetlana Saarela ◽  
Sebastian Schnell ◽  
Anton Grafström ◽  
Sakari Tuominen ◽  
Karin Nordkvist ◽  
...  
Keyword(s):  
Sample Size ◽  
Model Error ◽  
Second Phase ◽  
Auxiliary Data ◽  
Growing Stock ◽  
Model Based ◽  
Model Form ◽  
Moderate Effect ◽  
A Minor ◽  
Stock Volume

In this study, we investigate the use of model-based inference in forest surveys in which auxiliary data are available as a probability sample. We evaluate the effects of model form and sample size on estimators of growing stock volume, based on different types of remotely sensed auxiliary data. The study was performed through Monte Carlo sampling simulation using a two-phase sampling design within a simulated study area resembling the conditions in mid-western Finland. We show that the choice of model has a minor to moderate effect on the precision of model-based estimators. Similarly, the choice of estimator of the variance–covariance matrix of model parameter estimates, which is at the core of uncertainty assessment in model-based inference, was also found to have a minor to moderate effect on the precision of model-based estimators. Regarding sample sizes, the model error contribution to the total variance remains the same regardless of the sample size of the first phase (i.e., the size of the sample of auxiliary data); to reduce the model-error contribution, there is a need to increase the sample size of the second phase (i.e., the size of the sample of field plots for developing regression models). As a baseline for comparisons, model-assisted estimators were applied and found to be about equally precise as the model-based estimators, in accordance with the theory for the case when models are estimated from the sample data.

Innovating the Music and Sound Management Model in Tourist Destinations

2021 ◽  
Vol 5 (1) ◽  
pp. 25-39
Author(s):  
Diana Grgurić ◽  
Christian Stipanović
Keyword(s):  
Vital Role ◽  
Management Model ◽  
Second Phase ◽  
Tourist Destinations ◽  
Model Based ◽  
Tourism Product ◽  
Starting Point ◽  
Considerable Impact ◽  
Sound Management ◽  
Depth Interviews

This paper presents an analysis of the current level of sound and music valorisation in offerings in Croa-tian tourism and their promotion, and proposals for innovation, among which emphasis is placed on an audio management model based on the principles of acoustic ecology. Croatia is one of the more competitive Mediterranean destinations, focused on cultural tourism in which music offerings have a vital role. The first phase of research is based on in-depth interviews with and surveys of the representatives of tourist boards in Croatia, as a starting point for the situation analysis of music valorisation in Croatian tourism. The second phase is based on in-depth interviews with a target sample of tourist board repre-sentatives regarding music development as well as on the authors’ views based on recent scientific literature sources. The results of the study can be considered on two levels: the theoretical level, at which a management model for music valorisation in tourism is defined, and the practical level, with situation and scenario analysis of music valorisation in Croatian tourism and the design of an audio management model based on synergistic networking at both the micro-destination level and at the stakeholder level in order to diversify the attractions of the musical offering and create an integrated tourism product. Research results confirm that music has an insufficient position in strategic thinking in developing Croatian tourism, despite awareness of the considerable impact of music on the tourist experience in Croatia.

scholarly journals A Novel Spectral Clustering based on Local Distribution

2015 ◽  
Vol 5 (2) ◽  
pp. 361
Author(s):  
Jyotsna Kumar Mandal ◽  
Parthajit Roy
Keyword(s):  
Outlier Detection ◽  
Spectral Clustering ◽  
Second Phase ◽  
Local Distribution ◽  
Data Set ◽  
Benchmark Data ◽  
Model Based ◽  
Clustering Model ◽  
Proposed Model ◽  
Novel Variation

This paper proposed a novel variation of spectral clustering model based on a novel affinitymetric that considers the distribution of the neighboring points to learn the underlayingstructures in the data set. Proposed affinity metric is calculated using Mahalanobis distancethat exploits the concept of outlier detection for identifying the neighborhoods of the datapoints. RandomWalk Laplacian of the representative graph and its spectra has been consideredfor the clustering purpose and the first k number of eigenvectors have been consideredin the second phase of clustering. The model has been tested with benchmark data and thequality of the output of the proposed model has been tested in various clustering indicesscales.

scholarly journals Sequential model based optimization of partially defined functions under unknown constraints

2019 ◽  
Author(s):  
Candelieri Antonio
Keyword(s):  
Optimal Solution ◽  
Search Space ◽  
Bayesian Optimization ◽  
Feasible Region ◽  
Support Vector ◽  
Second Phase ◽  
Test Functions ◽  
Current Estimate ◽  
Sequential Model ◽  
Model Based

AbstractThis paper presents a sequential model based optimization framework for optimizing a black-box, multi-extremal and expensive objective function, which is also partially defined, that is it is undefined outside the feasible region. Furthermore, the constraints defining the feasible region within the search space are unknown. The approach proposed in this paper, namely SVM-CBO, is organized in two consecutive phases, the first uses a Support Vector Machine classifier to approximate the boundary of the unknown feasible region, the second uses Bayesian Optimization to find a globally optimal solution within the feasible region. In the first phase the next point to evaluate is chosen by dealing with the trade-off between improving the current estimate of the feasible region and discovering possible disconnected feasible sub-regions. In the second phase, the next point to evaluate is selected as the minimizer of the Lower Confidence Bound acquisition function but constrained to the current estimate of the feasible region. The main of the paper is a comparison with a Bayesian Optimization process which uses a fixed penalty value for infeasible function evaluations, under a limited budget (i.e., maximum number of function evaluations). Results are related to five 2D test functions from literature and 80 test functions, with increasing dimensionality and complexity, generated through the Emmental-type GKLS software. SVM-CBO proved to be significantly more effective as well as computationally efficient.

scholarly journals Model-based adaptive spatial sampling for occurrence map construction

2011 ◽  
Vol 23 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Nathalie Peyrard ◽  
Régis Sabbadin ◽  
Daniel Spring ◽  
Barry Brook ◽  
Ralph Mac Nally
Keyword(s):  
Spatial Sampling ◽  
Model Based ◽  
Map Construction

Representation, abstraction, and simple-minded sophisticates

2020 ◽  
Vol 43 ◽  
Author(s):  
Peter Dayan
Keyword(s):  
Decision Theory ◽  
Predictive Coding ◽  
Bayesian Decision Theory ◽  
Bayesian Decision ◽  
Model Based ◽  
Model Free

Abstract Bayesian decision theory provides a simple formal elucidation of some of the ways that representation and representational abstraction are involved with, and exploit, both prediction and its rather distant cousin, predictive coding. Both model-free and model-based methods are involved.

Grain Refinement in Titanium-Erbium Alloys

1974 ◽  
Vol 32 ◽  
pp. 522-523
Author(s):  
B. B. Rath ◽  
J. E. O'Neal ◽  
R. J. Lederich
Keyword(s):  
Electron Microscopy ◽  
Size Distribution ◽  
Grain Refinement ◽  
Grain Growth ◽  
Volume Fraction ◽  
Pure Titanium ◽  
Systematic Investigation ◽  
Second Phase ◽  
Titanium Matrix ◽  
Average Size

Addition of small amounts of erbium has a profound effect on recrystallization and grain growth in titanium. Erbium, because of its negligible solubility in titanium, precipitates in the titanium matrix as a finely dispersed second phase. The presence of this phase, depending on its average size, distribution, and volume fraction in titanium, strongly inhibits the migration of grain boundaries during recrystallization and grain growth, and thus produces ultimate grains of sub-micrometer dimensions. A systematic investigation has been conducted to study the isothermal grain growth in electrolytically pure titanium and titanium-erbium alloys (Er concentration ranging from 0-0.3 at.%) over the temperature range of 450 to 850°C by electron microscopy.

TEM Studies of Grain Boundary Films in Si3N4 Ceramics

1991 ◽  
Vol 49 ◽  
pp. 930-931
Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Hot Isostatic Pressing ◽  
Amorphous Film ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
High Temperature Mechanical Properties ◽  
Triple Points ◽  
Boundary Films

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.

Polishing process effect on the image of dispersed precipitates

1984 ◽  
Vol 42 ◽  
pp. 534-535
Author(s):  
C.T. Hu ◽  
C.W. Allen
Keyword(s):  
Matrix Material ◽  
Specimen Preparation ◽  
Second Phase ◽  
Precipitate Particle ◽  
Polishing Process ◽  
Second Phase Particles ◽  
The Matrix ◽  
Surface Profiles ◽  
Thinning Process

One important problem in determination of precipitate particle size is the effect of preferential thinning during TEM specimen preparation. Figure 1a schematically represents the original polydispersed Ni3Al precipitates in the Ni rich matrix. The three possible type surface profiles of TEM specimens, which result after electrolytic thinning process are illustrated in Figure 1b. c. & d. These various surface profiles could be produced by using different polishing electrolytes and conditions (i.e. temperature and electric current). The matrix-preferential-etching process causes the matrix material to be attacked much more rapidly than the second phase particles. Figure 1b indicated the result. The nonpreferential and precipitate-preferential-etching results are shown in Figures 1c and 1d respectively.

Structure of second phases in TiAl alloys containing Cr and B

1991 ◽  
Vol 49 ◽  
pp. 576-577
Author(s):  
Ernest L. Hall ◽  
Shyh-Chin Huang
Keyword(s):  
Grain Size ◽  
Second Phase ◽  
Structure And Properties ◽  
Tial Alloys ◽  
Second Phases ◽  
Interstitial Elements

Addition of interstitial elements to γ-TiAl alloys is currently being explored as a method for improving the properties of these alloys. Previous work in which a number of interstitial elements were studied showed that boron was particularly effective in refining the grain size in castings, and led to enhanced strength while maintaining reasonable ductility. Other investigators have shown that B in γ-TiAl alloys tends to promote the formation of TiB2 as a second phase. In this study, the microstructure of Bcontaining TiAl alloys was examined in detail in order to describe the mechanism by which B alters the structure and properties of these alloys.

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