Showing papers by "University of New Brunswick published in 1987"

Some NP-complete problems in quadratic and nonlinear programming

Abstract: In continuous variable, smooth, nonconvex nonlinear programming, we analyze the complexity of checking whether(a)a given feasible solution is not a local minimum, and(b)the objective function is not bounded below on the set of feasible solutions. We construct a special class of indefinite quadratic programs, with simple constraints and integer data, and show that checking (a) or (b) on this class is NP-complete. As a corollary, we show that checking whether a given integer square matrix is not copositive, is NP-complete.

New approach for calculating the normally ordered form of squeeze operators.

Abstract: A new method for directly obtaining the normally ordered form of single- and two-mode squeeze operators is presented. This method is based on the technique of ``integration within an ordered product.'' The operator expressions are derived using the coherent-state representation as well as the coordinate and the momentum representations. The method is very simple, and the approach has an intuitive basis that makes the squeezing property manifest at the outset.

A polynomial-time algorithm to find the shortest cycle basis of a graph

Abstract: Define the length of a basis of the cycle space of a graph to be the sum of the lengths of all cycles in the basis. An algorithm is given that finds a cycle basis with the shortest possible length in $O(m^3 n)$ operations, where m is the number of edges and n is the number of vertices. This is the first known polynomial-time algorithm for this problem. Edges may be weighted or unweighted. Also, the shortest cycle basis is shown to have at most ${{3(n - 1)(n - 2)} / 2}$ edges for the unweighted case. $O(mn^2 )$ algorithm to obtain a suboptimal cycle basis of length $O(n^2 )$ for unweighted graphs is also given.

Cognitive Styles: an integrated model

Abstract: Cognitive styles are potentially useful in education as a means of characterizing stable individual differences that influence the effectiveness of teaching and learning. However, anyone interested in using styles in either research or practice is faced with a literature that is not only disorganized but also dated. Little basic research is being done to clarify the conceptual and measurement problems that bedevil the field. One way to revive interest in basic research would be to link ‘traditional’ conceptions of cognitive styles with the more vigorous field of cognitive psychology. This might result in new ways of conceptualizing individual styles, as well as resolving the problem of the relationships between styles. In this paper, I take a step in this direction by integrating some of the more common conceptions of cognitive styles into an information processing model of cognition.

Isometries of the unit sphere

Abstract: It is shown that isometries between the unit spheres of finite dimensional Banach spaces necessarily map antipodal points to antipodal points.

Cumulative exergy consumption and cumulative degree of perfection of chemical processes

Abstract: The paper presents methods of calculating the cumulative exergy consumption and introduces the notion of the cumulative degree of perfection of the entire chain of production processes leading to the material under consideration. Tables of values calculated on the basis of cumulative energy consumption indices have been included.

Inventory policies under various optimizing criteria and variable markup rates

Abstract: This paper extends the deterministic EOQ model to reflect various optimizing criteria and alternative demand and price structures. Its primary purpose is to develop decision rules for the management of finished goods inventories, especially in retailing, where inventories are evaluated in the same way as any other investment, namely on their ability to generate profits, rather than on the traditional least-cost basis. To that effect, the models developed here consider demand to be a function of price, with price defined as a markup of unit cost. The decision variables are the order quantity and the markup rate. Possible optimizing objectives include profits, return on investment, or residual income, the three most widely used evaluators of short-term investment performance. Optimal solutions for each case are obtained and the resulting inventory policies evaluated.

Selected sleep disturbances in school children reported by parents: prevalence, interrelationships, behavioral correlates and parental attributions.

Abstract: Silmmasy.-Epidemiological, behavioral and etiological variables related to sleep disturbances were investigated in a survey of 1695 children in Grades 1 to 12 from 11 randomly selected schools. Sleep-walking, nighunares and sleep-talking were suongly associated with each other as well as to a family history of sleep-walking. Enuresis, however, was not related to the other sleep variables. Socioeconomic status of father was weakly related to enuresis and sleep-talking but not to sleep-walking or nightmares. Gender was not related to any of the sleep disturbances. The behavioral variables, physical activity, attention, emotional excitability, and feelings easily hurt showed a small association with the sleep disturbances. Parents most frequently attributed causes of sleep-walking and nighmares to over-tiredness and over-excitement. As well, parents' comments indicated that they tend to associate specific events such as illness or more often, frightening TV content wirh nighunares, but not sleepwalking.

Automated cartographic generalization for linear map features

Abstract: Cartographic generalization is the task of making smaller-scale maps (for example, 1:100,000) from larger-scale maps (for example, 1:20,000). An automated method is presented for generalization of linear features that are already in a topologically structured computer-readable form. The method consists of three stages: feature elimination, feature simplification, and interference detection and resolution. The first stage is implemented using English-like rules. These rules specify which map features are to be eliminated at the generalized map scale. They also control when the second and third stages are invoked. The second stage consists of the simplification of linear map features. A procedure for polyline simplification is presented, along with new algorithms for subdivision of linear features and riverbank combination. The third stage deals with interference and detection among linear map features. Interference may occur when a simplified feature is added to the generalized map. Due to the width of the symbol representing this feature, it may overlap another feature already on the generalized map. If that occurs, one or both of the features have to be displaced so as to eliminate the interference between them. This displacement may cause the end nodes of the displaced feature to be moved, which results in the propagation of the displacement to the features that are connected to these displaced end nodes. The algorithms used to detect feature interference and to perform the subsequent feature displacement propagation are described. A FORTRAN 77 computer program called MAPEX was written to perform automated generalization of linear map features. This program assumes a topologically structured input data file similar to the U.S. Geological Survey 1:24,000 scale Digital Line Graph map data files. To integrate the English-like rules with MAPEX, a rule compiler was written to translate the English-like rules to a FORTRAN 77 subroutine. The results of running MAPEX on a topologically structured test data file are given, along with the algorithmic details used in the implementation of MAPEX.

Modeling and Control Design for Wind Energy Power Conversion Scheme using Self-Excited Induction Generator

Abstract: This paper deals with dynamic modeling of self-excited induction generator connected to a supply system through a de link (converter-line commutated inverter) and digital control design for regulating the power transfer through the link. Using different sampling rates for the converter and inverter control loops, the proposed design ensures reduced reactive power burden on the induction generator. Results of implementation on a laboratory system are given.

Levels of endogenous indole-3-acetic acid in the vascular cambium region of Abies balsamea trees during the activity - rest - quiescence transition

Abstract: Indole-3-acetic acid (IAA) levels in the cambial region were measured by radioimmunoassay during the annual cambial activity - rest - quiescence transition at the crown top (current-year shoots) and at the middle and base of the stem of two 21-year-old Abies balsamea (L.) Mill. trees about 7.5 m in height. The IAA level declined throughout the experimental period (July 24 - December 3) at all positions in both trees. The earlywood - latewood transition, which occurred throughout each tree about the end of July, was associated in time with the largest decrease in the absolute amount of IAA. Tracheid production ceased towards the end of September, the cessation occurring earlier at the top of the tree than at the base. The cessation of tracheid production was only poorly correlated in time and space with the decline in IAA level, and it was not prevented by exogenous IAA. The results suggest that IAA level is involved in the control of tracheid radial enlargement, but not in the regulation of the cessation of tracheid production.

Towards a coexistence of paradigms in nursing knowledge development.

Abstract: During the last 35 years, nursing knowledge has known a surge in its development. Following the evolution of the scientific world, nursing first embraced the logical empiricist perspective of discovering and knowing. Historicism and, more recently, critical social theory have been explored as alternative ways of making knowledge in nursing. This paper discusses the evolution of nursing knowledge, considering its past and present activities. The authors suggest that a cooperative attitude amongst nurses, and a coexistence of various paradigms of knowledge development characterize the future of nursing. Nursing knowledge should be understood as a stage in its evolution and growth. The result of this process will never be a final static body of knowledge. Knowledge expansion will be encouraged through a process of integrating components from different research traditions, such that a multidimensional understanding of phenomena will be realised.

Extracules, Intracules, Correlation Holes, Potentials, Coefficients and All That

Abstract: A brief, subjective review is given of some concepts and functions which are important to an understanding of electron pair densities in position and momentum space. Intracule (relative motion) and extracule (centre of mass) densities are three dimensional contractions of electron pair densities that retain genuine two-electron character. Study of these quantities should add to an understanding of pair densities. Coulomb and Fermi holes need to be studied in order that electron pair correlation be understood in a physical and visual manner. This can be of utility in density functional models of exchange and correlation energies. In particular, the study of correlation energy generating potentials should lead to improved correlation energy functionals. Statistical correlation coefficients provide simple, global measures of electron pair correlation. One such coefficient is particularly interesting since it can be measured experimentally.

Machiavellianism, the Control Question Test and the detection of deception.

Abstract: Individuals, differing in levels of Machiavellianism, were involved in a mock crime psychophysiological detection of deception study. It was hypothesized that those scoring high on Machiavellianism would perceive detection results as more accurately reflecting their actual guilt or innocence, especially under conditions of high arousal, than those with low scores. The hypothesis was based on assumptions that subjects must appropriately discriminate amongst crime-relevant and irrelevant questions, that this discrimination is moderately difficult with Control Question Tests, and that high-Mach scorers under arousing conditions will make this discrimination more readily than low-Mach scorers. Partial support for the hypothesis was found in that guilty high-Mach scorers were more accurately detected than guilty low-Mach scorers. This result did not hold for innocent Mach scorers, and there was no augmentation of the effect in conditions designed to increase emotional arousal.

Masculinity, femininity, life stress, and depression

Abstract: This study explored the effects of masculinity, femininity, and life stress on depression. Four hundred and two subjects (266 females and 136 males) completed the Bem Sex Role Inventory, the Life Experiences Survey, and the Beck Depression Inventory. Results of a regression analysis indicated significant effects of life stress, masculinity, and femininity on depression. Although masculinity and, to a lesser extent, femininity, were significant predictors of depression, life stress accounted for a substantially greater proportion of the variance. The implications of the results are discussed with respect to the role of masculinity and femininity as susceptibility factors in depression associated with stressful life experiences.

Postembryonic differentiation of serotonin-immunoreactive neurons in fleshfly optic lobes developing in situ or cultured in vivo without eye discs

Abstract: The differentiation of serotonin-immunoreactive (5-HTi) neurons in the optic lobes of fleshflies was studied during in situ development and in in vivo cultures. All 5-HTi neurons with cell bodies in the imaginal optic lobes differentiate during postembryonic (pupal) development. These are local anaxonal neurons. In addition there are two large 5-HTi bilateral neurons that connect all optic lobe neuropil regions on both sides of the brain and have their cell bodies in the midbrain proper. Deafferentation of optic lobes cultured in vivo leads to drastic reduction in optic lobe volume and increased cell death. All the 5-HTi neurons differentiate after deafferentation but their morphology changes. The neuropil receiving the photoreceptor inputs, the lamina, degenerates but a disorganized “pseudolamina” is formed by the processes of the two large 5-HTi neurons. The layering of the optic lobe neuropils cannot be distinguished and 5-HTi processes form novel projectional patterns. Hence, the 5-HTi neurons do not require afferent inputs from the retina for their differentiation and survival, but the effect on other optic lobe interneurons is reflected in the morphological plasticity of the 5-HTi neurons.

Characterization of the excited electronic states of the SH radical by ab initio methods

Abstract: Ab initio MRD-CI calculations have been performed for the SH radical in its low-lying valence states as well as vertically for the first Rydberg terms (2π24s, 2π24p and 2π23d). The lowest 1 4,2Σ-, 1 2Δ and 2 2Σ+ states are found to be of valence character in the vertical region, while a Rydberg structure was suggested by an earlier ab initio study. For the bound X 2Π i and A 2Σ+ various molecular constants such as spectroscopic parameters, dipole moments, Franck-Condon factors and spin-orbit constant are reported. The predissociation of A 2Σ+ in its low-vibrational levels observed by Ramsay is confirmed to be caused by the repulsive 1 4,2Σ- states. Furthermore, a complete reassignment of the electronic structure of the experimentally measured Rydberg levels is given: all these states are found to have a 2π24s (B 2Σ- and C 2Δ), 2π23d σ (E 2Σ-) and 2π2 nd σ, n = 3–6 (D, F, G, H 2Δ) electronic configuration respectively. The E 2Σ- and C 2Δ states are classified here for the first time, while the B 2Σ- has be...

The economic design of control charts: a renewal theory approach

Abstract: Economic models for the design of control charts based on Duncan's approach1 have been well studied in the recent past We present an alternative approach to the development of a few of these models using renewal equations The main emphasis here is to study the role of the probability model associated with the process failure mechanism It is demonstrated that the expressions Tor the expected cycle length E( T) and the expected cost per cycle E( C) are easier to obtain by the proposed renewal equation approach than by adopting the traditional approach Furthermore, it is observed that certain non-Markovian shock models may be analyzed by adopting a renewal equation approach, whereas Duncan's approach has not been used with any non-Markovian model

Design and analysis of parallel Monte Carlo algorithms

Abstract: This paper demonstrates that the potential of intrinsic parallelism in Monte Carlo methods, which has remained essentially untapped so far, can be exploited to implement these methods efficiently on SIMD and MIMD computers. Two basic static and dynamic computation assignment schemes are proposed for assigning the primary estimate computations (PECs) to processors in a parallel computer. These schemes can be used to design parallel Monte Carlo algorithms for many applications. The time complexity analyses of static computation assignment (SCA) schemes are carried out using some results from order statistics, whereas those of dynamic computation assignment (DCA) schemes are carried out using results from order statistics, renewal and queueing theories. It is shown that for smaller number of processors, linear speedup can be achieved with the SCA schemes and the speedup almost equal to the number of processors can be achieved with the DCA schemes. Some computational results for Monte Carlo solutions of Lapla...

Combinatorial Optimization Problems with Soft and Hard Requirements

Abstract: In this paper, the authors describe a heuristic principle for the solution of an important class of problems. Using real-world examples, it is then shown how some difficult combinatorial problems are modelled and solved by the suggested principle. In one case, a detailed discussion of the implementation of the solution is also provided.