Generating nonorthogonal bases for signal representation

The representation of functions in a basis function expansionz(t)= k=1/=,a _k> x _k (t) is straightforward when the basis functionsx _k (t) are orthogonal. There has been very little work up to this time in determining how to use nonorthogonal bases in signal representation. On the other hand, applications in data compression and signal synthesis often require using specific tailor-made bases. Presented here is a method for constructing very general nonorthogonal bases.Orthogonality has often been used to show that a basis spans the set of functions of interest and to calculate the coefficients of the representation. In this paper, both of these fundamental aspects are addressed for nonorthogonal bases. A new basis {y _k (t)} is obtained by performing a linear transformation on a known existing basis {x _k (t)}. This transformation is constructed such that the coefficients of signal representation on the new basis are readily found. Then, a useful and sufficient condition is placed upon the new basis such that representations converge.The fundamental methods are applied to the standard examples of signal representation. The complex sinusoids, the Rademacher functions, the orthogonal polynomials, and the decaying exponentials are used as the original basis {x _k (t)} from which a new basis {y _k (t)} is generated. Two examples are given to illustrate general applications: one in signal synthesis and one in signal analysis.     

Separation in D‐optimal experimental designs for the logistic regression model

The D‐optimality criterion is often used in computer‐generated experimental designs when the response of interest is binary, such as when the attribute of interest can be categorized as pass or fail. The majority of methods in the generation of D‐optimal designs focus on logistic regression as the base model for relating a set of experimental factors with the binary response. Despite the advances in computational algorithms for calculating D‐optimal designs for the logistic regression model, very few have acknowledged the problem of separation, a phenomenon where the responses are perfectly separable by a hyperplane in the design space. Separation causes one or more parameters of the logistic regression model to be inestimable via maximum likelihood estimation. The objective of this paper is to investigate the tendency of computer‐generated, nonsequential D‐optimal designs to yield separation in small‐sample experimental data. Sets of local D‐optimal and Bayesian D‐optimal designs with different run (sample) sizes are generated for several “ground truth” logistic regression models. A Monte Carlo simulation methodology is then used to estimate the probability of separation for each design. Results of the simulation study confirm that separation occurs frequently in small‐sample data and that separation is more likely to occur when the ground truth model has interaction and quadratic terms. Finally, the paper illustrates that different designs with identical run sizes created from the same model can have significantly different chances of encountering separation.     

Modeling thermal and stress behavior of the fuel–clad interface in monolithic fuel mini-plates

A fuel development and qualification program is in process with the objective of qualifying very high density monolithic low enriched uranium–molybdenum fuel for high-performance research reactors. The monolithic fuel foil creates differences in the mechanical and structural characteristics of the fuel plate because of the planar interface created by the fuel foil and cladding. An initial finite element analysis model has been developed to investigate worst-case scenarios for the basic monolithic fuel plate structure using typical mini-plate irradiation conditions in the Advanced Test Reactor. Initial analysis shows that the stress normal to the fuel–clad interface dominates during irradiation and that the presence of small, rounded delaminations at the interface is not of great concern. However, larger and/or fuel–clad delaminations with sharp corners can create areas of concern, as maximum principal cladding stress, strain, displacement, and peak fuel temperature are all significantly increased. Furthermore, stresses resulting from temperature gradients that cause the plate to bow or buckle in an unconstrained fuel plate configuration is greatly enhanced in a constrained fuel plate configuration. The sensitivities of the model and input parameters are discussed, along with some overlap of initial experimental observations using as-fabricated plate characterization and post-irradiation examination.     

Analytical study of a solution-processed diode based on ZnO nanoparticles using multi-walled carbon nanotubes as Schottky contact

Journal of Materials Science: Materials in Electronics - The search for good electrodes processed by solution has interested several niches to produce printed solar cells, lighting emitting diodes,...     

A novel hybrid resampling for semiconductor wafer defect bin classification

Generally, defective dies on semiconductor wafer maps tend to form spatial clusters in distinguishable patterns which contain crucial information on specific problems of equipment or process, thus it is highly important to identify and classify diverse defect patterns accurately. However, in practice, there exists a serious class imbalance problem, that is, the number of the defective dies on semiconductor wafer maps is usually much smaller than that of the non-defective dies. In various machine learning applications, a typical classification algorithm is, however, developed under the assumption that the number of instances for each class is nearly balanced. If the conventional classification algorithm is applied to a class imbalanced dataset, it may lead to incorrect classification results and degrade the reliability of the classification algorithm. In this research, we consider the semiconductor wafer defect bin data combined with wafer warpage information and propose a new hybrid resampling algorithm to improve performance of classifiers. From the experimental analysis, we show that the proposed algorithm provides better classification performance compared to other data preprocessing methods regardless of classification models.     

Reflections on the virtues of modularity: a case study in linux security modules

Developing a modular system that properly supports a range of security models is challenging. The work presented here details our experiences with the modular Linux security framework called Linux Security Modules, or LSMs. Throughout our experiences we discovered that the developers of the LSM framework made certain tradeoffs for speed and simplicity during implementation, and consequently leaving the framework incomplete. Our experiences show at which points the theory of the LSM differs from reality, and details how these differences play out when developing and using a custom LSM. Copyright © 2009 John Wiley & Sons, Ltd.     

Long‐chain omega‐3 from low‐trophic‐level fish provides value to farmed seafood

Low‐trophic‐level fish are a crucial source of long‐chain (LC) omega‐3 fatty acids for farmed fish and humans. Many farm‐raised fish species have a clear need for these nutrients. Farmed fish deposit the LC omega‐3s in their flesh and transfer them up the food chain. However, the content of LC omega‐3s in farm‐raised seafood continues to decline, while the content of shorter‐chain plant‐sourced omega‐3s, and pro‐inflammtory omega‐6s continue to increase. This reduces its nutritional worth. The value of low‐trophic‐level fish is often viewed merely as its price at the dock. Some reports and metrics steer public attention towards the mass balance between quantities of low‐trophic‐level fish and farmed seafood. However, the the nutritional value of seafood is more important than its mere quantities. The role of low‐trophic‐level fish in human nutrition, health, and wellbeing is a fundamental component of its economic value to society.     

‘Assessing the visual impacts of urbanization from the highway: a visual evaluation of the South Fork interchange site,North Bend,Washington’

This study is noteworthy as an application at project design scale of a methodology developed in 1976 by Jones & Jones for the Federal Highway Administation course ‘Esthetics and Visual Resource Management’ currently being given to highway professionals around the country. It also demonstrates the transfer of this methodology from highway facilities to urbanization.