Neighborhood Pattern Research Articles

An Efficient Built-In Self-Test Algorithm for Neighborhood Pattern- and Bit-Line-Sensitive Faults in High-Density Memories

As the density of memories increases, unwanted interference between cells and the coupling noise between bit-lines become significant, requiring parallel testing. Testing high-density memories for a high degree of fault coverage requires either a relatively large number of test vectors or a significant amount of additional test circuitry. This paper proposes a new tiling method and an efficient built-in self-test (BIST) algorithm for neighborhood pattern-sensitive faults (NPSFs) and new neighborhood bit-line sensitive faults (NBLSFs). Instead of the conventional five-cell and nine-cell physical neighborhood layouts to test memory cells, a four-cell layout is utilized. This four-cell layout needs smaller test vectors, provides easier hardware implementation, and is more appropriate for both NPSFs and NBLSFs detection. A CMOS column decoder and the parallel comparator proposed by P. Mazumder are modified to implement the test procedure. Consequently, these reduce the number of transistors used for a BIST circuit. Also, we present algorithm properties such as the capability to detect stuck-at faults, transition faults, conventional pattern-sensitive faults, and neighborhood bit-line sensitive faults.

Neighborhood Patterns of Subprime Lending: Evidence from Disparate Cities

This paper estimates, for 7 cities, a model of prime versus subprime allocation of loans in 1997 and 2002 based on both individual loan and neighborhood attributes. The paper is directly interested in the effect of neighborhood racial and ethnic composition on the likelihood of receiving a subprime loan. The paper also allows for interaction of borrower race and ethnicity with neighborhood attributes. A unique feature of the paper is that it provides additional neighborhood controls for the aggregate level of credit risk and the neighborhood level of equity risk. The paper finds some evidence for tightening loan standards over the 5-year period in the subprime market. In both years, even with risk controls, the minority share of neighborhood is consistently significant and positively related to subprime share. Furthermore, neighborhood education level is consistently significant and negatively related to subprime lending.

A DYNAMIC MODEL OF RESIDENTIAL SEGREGATION

Using dimes and pennies on a checkerboard, Schelling (1971, 1978) studied the link between residential preferences and segregational neighborhood patterns. While his approach clearly has methodological advantages in studying the dynamics of residential segregation, Schelling's checkerboard model has never been rigorously analyzed. We propose an extension of the Schelling model that incorporates economic variables. Using techniques recently developed in stochastic evolutionary game theory, we mathematically characterize the model's long-term dynamics.

Neighborhood patterns of subprime lending: Evidence from disparate cities

This article estimates a model of prime versus subprime allocation of loans for seven cities in 1997 and 2002; the model is based on both individual loan and neighborhood attributes. Of immediate interest is the effect of neighborhood racial and ethnic composition on the likelihood of receiving a subprime loan. We also allow for the interaction of borrower race and ethnicity with neighborhood attributes. A unique feature of our study is that it provides additional neighborhood controls for the aggregate level of credit risk and the neighborhood level of equity risk. We find some evidence of tightening loan standards in the subprime market over this five‐year period. Even with risk controls, the neighborhood minority share is consistently significant and positively related to subprime share in both years. Furthermore, the neighborhood educational level is consistently significant and negatively related to subprime lending.

The concept of discrete description of plant ontogenesis and cellular automata models of plant populations

The article represents a link between the concept of discrete description of the ontogenesis of plants and the cellular automata approach for the spatial-temporal modelling of plant population dynamics. The continuous process of individual plant development may be subdivided into several stages on the basis of morphological indicators reflecting functional importance of plants at different stages. The number and duration of age stages may vary from species to species, among life-forms within species, and under different environment conditions. The duration of age stages and the probability of transition from one stage to another for a given plant depend on the plant’s neighbourhood pattern, the type of ontogenesis and the site conditions. Such data are available from numerous field studies. The presented approach allows simulation of a plant population as a set of cellular automata located on a plane. The age stages of these automata can be changed according to simple rules, which reflect the types of plant ontogenesis, different life spans of age states, and different sizes of plants in the neighbourhood. This approach is different from matrix models, which are usually used for this purpose, in that here we can directly simulate the role of space interactions in the population dynamics. We constructed some cellular automata models based on experimental data, which reflect the ontogenesis types and life-forms of plants. The models demonstrate that simple rules of plant development with simply defined local interactions lead to complicated dynamics. The results show new possibilities of applications of discrete simulation modelling for analysis of plant populations and community dynamics.

Neighborhood pattern-sensitive fault testing and diagnostics for random-access memories

The authors present test algorithms for go/no-go and diagnostic test of memories, covering neighborhood pattern-sensitive faults (NPSFs). The proposed test algorithms are March based, which have linear time complexity and result in a simple built-in self-test (BIST) implementation. Although conventional March algorithms do not generate all neighborhood patterns to test the NPSFs, they can be modified by using multiple data backgrounds such that all neighborhood patterns can be generated. The proposed multibackground March algorithms have shorter test lengths than previously reported ones, and the diagnostic test algorithm guarantees 100% diagnostic resolution for NPSFs and conventional RAM faults. Based on the proposed algorithms, the authors also present a cost-effective BIST design. The BIST circuit is programmable, and it supports March algorithms, including the proposed multibackground one.

Built-in self-test for folded bit-line Mbit DRAMs

In this paper an efficient and comprehensive algorithm for deriving near optimal parallel tests for neighborhood pattern sensitive faults (NPSFs) detection for an arbitrary type of neighborhood is presented. When k is odd (even) it is based on the decomposition of a directed (undirected) k-cube into a minimal number of edge-disjoint tours. The approach considerably simplifies test-pattern generator (TPG) requirements and makes it suitable for implementation on a VLSI chip. The proposed algorithm is utilized to derive a parallel self-test for detection of unidirectional NPSFs in solded bit-line Mbit DRAM chips. An integrated test strategy covers the most typical functional and parametric faults by execution of retention and marginal tests during the parallel test for unidirectional NPSFs detection. Results showed an improved test coverage of k-coupling faults by approximately 10–65% compared to “tiling” method when k varies from 2 to 9. The total chip area expansion is less than 0.5% for Mbit DRAMs. A test length is 1072 N w when a lower bound is 1024 N w, where N w is the number of word-lines. Thus 64 MBit DRAM {8192 × 8192} is tested within a second when the speed of the test clock is 10 MHz.

Testing reconfigured RAM's and scrambled address RAM's for pattern sensitive faults

State-of-the-art RAM chips are designed with spare rows and columns for reconfiguration purposes. After a RAM chip is reconfigured, physically adjacent spare cells may no longer have consecutive logical addresses. Another aspect that results in distinct logical and physical neighborhoods in RAM's is the scrambling of address lines, necessitated by the need to minimize the overall silicon area and the critical path lengths. Test algorithms used to test reconfigured RAM's and scrambled address RAM's for the detection of physical neighborhood pattern sensitive faults have to consider that the physical and logical neighborhoods are different and that the address mapping of the reconfigured RAM is no longer available. In this paper, we present a test algorithm that detects static five-cell physical neighborhood pattern sensitive faults in reconfigured RAMs and RAMs with scrambled address lines. This algorithm is based on the widely used MSCAN and Marching test algorithms, and requires only O(N[log/sub 2/N]) reads and writes to test an N-bit RAM array.

Generic DFT approach for pattern sensitive faults in word-oriented memories

The testability problem of word-oriented memories (WOMs) for pattern sensitive faults is addressed. A novel design for testability (DFT) strategy allows efficient built-in self-testing (BIST) of WOMs. By proper selection of the memory array tiling scheme, it is possible to implement O(√n) BIST algorithms which test WOMs for various types of neighbourhood pattern sensitive faults (NPSFs). The inputs of the column decoders are modified to allow parallel writing into multiple words, and coincidence comparators are added to allow parallel verification of row data with minimal effect on chip area and performance.

On-chip testing of random access memories

This article gives an overview of the Built-In Self-Test techniques for stand alone Random-Access Memory chips. It identifies the limitations of the existing fault models and the test algorithms used to test large RAMs. Methods to reduce test time for testing large RAMs are categorized. The article argues that even linear time test algorithms must use architecture and design for testability induced parallelisms to keep the total test time to an acceptable limit. Following that two algorithms are presented that can be used to test large RAMs for neighborhood pattern sensitive faults. Test lengths and test time for application of these algorithms are computed and it is suggested that a microprogrammed controller based scheme be used to implement self-test in stand alone RAMs.

A fuzzy logic and neural network approach to boundary detection for noisy imagery

Abstract In this paper, an edge relaxation method utilizing fuzzy logic and neural networks is presented. The goal is to extract physically meaningful edge segments. The candidates for edge segments are first estimated using a local derivative operator with a window of small size. To enhance the performance of edge detection, in addition to the output of a derivative operator, the spatial relationships among the neighboring edge segments around an edge segment of interest are used as additional source of information. Fuzzy rules, each of which is associated with a neighborhood pattern defined by the spatial relationships among the neighboring edge segments, are used as a computational framework of collecting the evidence for the existence of an edge segment. These fuzzy rules are trained by a specially structured neural network which performs fuzzy reasoning operation. Through a series of experiments, the proposed edge relaxation scheme is found to exhibit reasonable performance of eliminating false edges, strengthening weak real edges and bridging small gaps between edge segments on object boundary.

Hypergraph coloring and reconfigured RAM testing

RAM decoders are designed with a view to minimize the overall silicon area and critical path lengths. This can result in designs in which-physically adjacent rows (and columns) are not logically adjacent. Even if physically adjacent rows (and columns) are logically adjacent, there are other issues that preclude the possibility of identical physical and logical addresses. State-of-the-art memory chips are designed with spare rows and spare columns for reconfiguration purposes. After a memory chip is reconfigured, physically adjacent cells may no longer have consecutive logical addresses. Test algorithms used at later stages for the detection of physical neighborhood pattern sensitive faults have to consider the fact that the address mapping of the memory chip is no longer available. We present test algorithms to detect 5-cell and 9-cell physical neighborhood pattern sensitive faults and arbitrary 3-coupling faults, even if the logical and physical addresses are different and the physical-to-logical address mapping is not available. These algorithms have test lengths of O(N[log/sub 3/N]/sup 4/) and O(N[log/sub 3/N]/sup 2/), respectively, for N-bit RAMs, and are especially suited for testing reconfigured DRAMs. They also detect other conventional faults such as stuck-at faults and decoder faults. These test algorithms are based on efficiently identifying all triplets of objects among a group of n objects. We formulated this triplet identification problem as a hypergraph coloring problem, and developed an efficient 3-coloring algorithm that colors the n vertices of a complete uniform hypergraph of rank 3 such that each edge of the hypergraph is trichromatically colored in at most [log/sub 3/n]/sup 2/ coloring steps.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The integration of socioeconomic and physical resource data for applied land management information systems

Geographic information systems (GIS) have been seen as an important enabling technology in the integration of satellite remote sensing and more conventional forms of land use information. The development of GIS has closely followed perceived application needs in physical geography and led to the implementation of numerous digital databases for land resources management. However, data relating to the human population and its socioeconomic characteristics have been poorly integrated with these advances for a number of reasons. Geographic information processing in the social sciences has tended to lag behind the development of systems for physical applications and, at a more fundamental level, there are important differences in the way in which socioeconomic phenomena have been conceptualized and modelled. Nevertheless, an understanding of the distribution and characteristics of human activity has an increasingly important role to play in many questions relating to the management of the physical environment. This paper seeks to demonstrate the application of some developments in socioeconomic analysis using GIS to integrate conventional physical resource data with socioeconomic information in the context of land use planning. These involve the modelling and analysis of population information in a raster GIS environment, incorporating contemporary geodemographic techniques and providing valuable information on the analysis of settlement and neighbourhood patterns and the distribution of residential, commercial and industrial activities.

Photoelastic Study of Friction

A new method of measuring the normal and sliding loads associated with multiple point contact is introduced. A multiple point contact is modeled with a steel die with a profile that simulates a rough surface. A very large scale factor is used in modeling this surface. The steel die is placed in contact with a photoelastic model of a half plane and is subjected to a normal load. This normal load is partitioned over the multiple points of contact producing an isochromatic fringe pattern that describes the stress distribution in the local neighborhood of the contact points. A sliding load is then imposed on the model which destroys the symmetry of this fringe pattern. The fringe data in this pattern is sufficient to determine the local loads Pi and Qi and the local coefficient of friction fi = Qi / Pi at each contact point. An overdeterministic method is introduced which gives the solution for Pi, Qi and fi using many data points taken from the isochromatic pattern in the local neighborhood of the contacts.

A photoelastic study of friction at multipoint contacts

A new method of measuring the normal and sliding loads associated with multiple-point contact is introduced. A multiple-point contact is modeled with a steel die with a profile that simulates a rough surface. A very large scale factor is used in modeling this surface. The steel die is placed in contact with a photoelastic model of a half plane and is subjected to a normal load. This normal load is partitioned over the multiple points of contact producing an isochromatic fringe pattern that describes the stress distribution in the local neighborhood of the contact points. A sliding load is then imposed on the model which destroys the symmetry of this fringe pattern. The fringe data in this pattern are sufficient to determine the local loadsPi andQi and the local coefficient of frictionfi=Qi/Pi at each contact point. An overdeterministic method is introduced which gives the solution forPi,Qi andfi using many data points taken from the isochromatic pattern in the local neighborhood of the contacts.

Fast power system voltage prediction using knowledge-based approach and on-line box data creation

The paper presents an algorithm for fast power system contingency analysis using pattern recognition. The pattern space is clustered into data boxes for ease of search and flexibility of programming. The addressable memory structure of the pattern space decouples the voltage prediction problem into subproblems for one busbar and one contingency at a time. To reduce the working memory, the algorithm learns from the short-term load trend and selects only a few data boxes for on-line processing. Further computational savings and improvements in accuracy are achieved by adopting an innovative wafer data box structure that also facilitates subsequent refinement by additions/deletions of patterns acquired from real-time operational experience. Other techniques, with the same objectives, include a procedure for eliminating insignificant features from data boxes and clumping their effects into correction terms; a methodology for selecting the best expression for voltage prediction; and a pattern filter for placing the target state at the geographical centre of the training set nearest neighbourhood patterns.

Monte-Carlo simulation of some interacting particle systems in the plane: Towards the theory of underpotential deposition

We propose a general model for the study of the dynamics of underpotential deposition. Basically, the model involves an interacting particle system on a two-dimensional (square or triangular) lattice, where the rates of birth (adsorption of a particle onto the lattice) are constant, and the rates of death (desorption) depend only on the neighborhood pattern, i.e., the configuration of occupied sites surrounding the particle. Essentially, the more neighbors a molecule has, the more stable its position in the layer is. A series of Monte-Carlo simulations of this model has been conducted wherein we study the coverage of the surface as a function of time as well as its derivative (coverage current). We also propose and analyze estimates of two different quantities related to the clustering effect: the conditional entropy of the distribution of occupied sites in different patterns and an index of complexity of clusters which, essentially, is the ϵ-entropy of the cluster's border.

Cancer Incidence and Electromagnetic Radiation

A neighborhood pattern of cancer incidence was found in the city of Wichita, Kansas with the suggestion of a time element in its appearance. Cancer tended to occur on leading terrain crests relative to radar transmissions and was less frequent in the valleys. A formula is presented that relates the incidence of cancer, terrain, and the presence of microwave radiation.

Quantitative genetics of skeletal nonmetric traits in the rhesus macaques on Cayo Santiago. II. Phenotypic, genetic, and environmental correlations between traits.

The general lack of phenotypic correlation among skeletal nonmetric traits has been interpreted as indicating a lack of genetic correlation among these traits. Nonmetric traits scored on animals in the skeletal collection of rhesus macaques from Cayo Santiago are used to calculate phenotypic, genetic, and environmental correlations between traits. The results show that even when phenotypic correlations are low, there may be large, significant genetic correlations among these traits. The genetic correlation pattern suggests that genes which affect nonmetric trait variation act primarily at a local level in the cranium, even though there are genes with pleiotropic effects on skeletal nonmetric traits throughout the cranium. Environmental and phenotypic correlations do not show this neighborhood pattern of correlation.

Migration of a bubble with adsorbed film in a Hele-Shaw cell

The slow motion of a circular cylindrical bubble in Hele-Shaw flow has been investigated. It is assumed that surface-active material is present on the bubble surface, forming a film of monomolecular thickness. The bubble drags an almost annular region of fluid at all times. An idealized flow model allows the description of the phenomena observed in the experiments. An approximate formula for the migration velocity has been derived, in doing so the effect of the complicated flow pattern in the direct neighborhood of the bubble was evaluated by means of suitable experiments.