Accurate singular values and differential qd algorithms

Summary. We have discovered a new implementation of the qd algorithm that has a far wider domain of stability than Rutishauser's version. Our algorithm was developed from an examination of the {Cholesky~LR} transformation and can be adapted to parallel computation in stark contrast to traditional qd. Our algorithm also yields useful a posteriori upper and lower bounds on the smallest singular value of a bidiagonal matrix. The zero-shift bidiagonal QR of Demmel and Kahan computes the smallest singular values to maximal relative accuracy and the others to maximal absolute accuracy with little or no degradation in efficiency when compared with the LINPACK code. Our algorithm obtains maximal relative accuracy for all the singular values and runs at least four times faster than the LINPACK code. Received August 8, 1993/Revised version received May 26, 1993     

Asymptotic expansions in sequential estimation for the first-order random coefficient autoregressive model: Regenerative approach

Edgeworth expansions for the distribution of a sequential least squares estimator in the random coefficient autoregressive (RCA) model are derived. The regenerative approach to second-order asymptotic analysis of Markov-type statistical models is developed.     

High-field recombination electroluminescence in vacuum-deposited anthracene and doped anthracene films

The electroluminescence (EL) study of anthracene and tetracene-doped anthracene films deposited by a vacuum evaporation onto a substrate at temperatureT ₀=–60 °C is reported. Such films show high resistence to electrical breakdown so that their EL behaviour at high electric fields up to above 10⁶ V/cm could be investigated. The high-field EL is interpreted in terms of electron-hole recombination mechanisms with creation of emitting singlet excitons; the electron and hole concentration being limited by injection at metal contacts and by field-independent carrier velocities. The theoretical expression for current density follows the experimental data for fields above 4×10⁵ V/cm at room temperature and the EL intensity is predicted to be a power function of the measured current. It is suggested that in pure anthracene layers the power is determined by the contact injection conditions, i.e. by barrier heights and the effective masses of holes and electrons. In the doped films a guest molecules-induced energy trap distribution leads to a decrease of the power as confirmed by the experimental plots of the host EL intensity versus current density.The work supported in part by the Polish Academy of Sciences under Program MR.I.9     

On top-down splaying

The splay tree is a self-adjusting binary search tree which has a good amortized performance. This paper studies some properties of top-down splay trees. Different ways to charge for the primitive operations of top-down splaying are discussed. We also give some empirical results concerning the behaviour of different top-down restructuring algorithms.This work was supported by the Academy of Finland.     

A generalized,one-way,stackless quicksort

This note generalizes the one-way, stackless quicksort of Huang and Knuth to work for any type of sort key. It thus proves that quicksort can run with minimal space inO(N logN) average time.On leave from FH Fulda, D-6400 Fulda (Germany).     

Corrections to Lee's visibility polygon algorithm

We present a modification and extension of the (linear time) visibility polygon algorithm of Lee. The algorithm computes the visibility polygon of a simple polygon from a viewpoint that is either interior to the polygon, or in its blocked exterior (the cases of viewpoints on the boundary or in the free exterior being simple extensions of the interior case). We show by example that the original algorithm by Lee, and a more complex algorithm by El Gindy and Avis, can fail for polygons that wind sufficiently. We present a second version of the algorithm, which does not extend to the blocked exterior case.This work was partially supported by grants from the Central Research Fund of the University of Alberta and the Natural Sciences and Engineering Research Council of Canada.     

Comparison of Boolean algebras

In this work, some results related to superatomic Boolean interval algebras are presented, and proved in a topological way. Let x be an uncountable cardinal. To each I x, we can associate a superatomic interval Boolean algebra B _I of cardinality x in such a way that the following properties are equivalent: (i) I I x, (ii) B _I is a quotient algebra of B _J, and (iii) there is an homomorphism f from B _J into B _I such that for every atom b of B _I, there is an atom a of B _J satisfying f(a)=b. As a corollary, there are 2 ^x isomorphism types of superatomic interval Boolean algebras of cardinality x. This case is quite different from the countable one.     

The truncatedSVD as a method for regularization

The truncated singular value decomposition (SVD) is considered as a method for regularization of ill-posed linear least squares problems. In particular, the truncated SVD solution is compared with the usual regularized solution. Necessary conditions are defined in which the two methods will yield similar results. This investigation suggests the truncated SVD as a favorable alternative to standard-form regularization in cases of ill-conditioned matrices with well-determined numerical rank.This work was carried out while the author visited the Dept. of Computer Science, Stanford University, California, U.S.A., and was supported in part by National Science Foundation Grant Number DCR 8412314, by a Fulbright Supplementary Grant, and by the Danish Space Board.     

Wettability and surface energy of parylene F deposited on PDMS

For the first time, the wettability and surface energy of parylene F were investigated. The results showed that parylene F had a hydrophobic surface with an eigen water contact angle of 104.7 ± 0.6°. We found that 3.5 μl probe liquid was an optimal value for the contact angle measurement of parylene F. Moreover, we found that the Lifshitz–van der Waals/acid–base approach was unsuitable for determining the surface energy of parylene F, whereas the Owens–Wendt–Kaelble approach and the limitless liquid–solid interface wetting system were compatible. The surface energy of parylene F was estimated to be 27.06 mJ/m² (Owens–Wendt–Kaelble) and 40.41 mJ/m² (Limitless liquid-solid interface wetting system). Furthermore, this investigation also provided a reference for the applications of empirical and physics-based semi-empirical approaches for the estimation of surface energy.     

A MINI MULTI-GAS DETECTION SYSTEM BASED ON INFRARED PRINCIPLE

To counter the problems of gas accidents in coal mines, family safety resulted from using gas, a new infrared detection system with integration and miniaturization has been developed. The infrared detection optics principle used in developing this system is mainly analyzed. The idea that multi gas detection is introduced and guided through analyzing single gas detection is got across. Through researching the design of cell structure, the cell with integration and miniaturization has been devised. The way of data transmission on Controller Area Network (CAN) bus is explained. By taking Single-Chip Microcomputer (SCM) as intelligence handling, the functional block diagram of gas detection system is designed with its hardware and software system analyzed and devised. This system designed has reached the technology requirement of lower power consumption, mini-volume, big measure range, and able to realize multi-gas detection.