Showing papers by "National Tsing Hua University published in 1976"

Application of Principal Component Analysis to Multikey Searching

Abstract: In this paper, we shall introduce a concept widely used by statisticians, the principal component analysis technique. We shall show that this principal component analysis technique can be used to create new keys from a set of old keys. These new keys are very useful in narrowing down the search domain. We shall also show that the projections on the first principal component direction can be viewed as hashing addresses for the best-match searching problem.

An experimental study of convective instability in the thermal entrance region of a horizontal parallel‐plate channel heated from below

Abstract: This paper presents results of an experimental investigation on the onset of longitudinal columnar vortices due to buoyant forces in the thermal entrance region of a horizontal parallel-plate channel heated from below. Channels with width 30 cm and heights h = 2, 3 and 4.5 cm were employed in the experiment. The instability of the convective motion is caused by the effects of temperature gradients in both longitudinal and vertical directions and was observed by a direct flow-visualization technique using smoke. Photographs of the front and top views of the vortex rolls are presented. Experimental results indicate that the wave number of vortex rolls remains constant along the flow direction and tends to approach the theoretical value as the channel width-height ratio increases. It was also observed that the critical Rayleigh number from flow visualization is 1.4 to 10 times higher than the critical value from linear theory. On presente dans le travail les resultats d'une etude experimentale de l'assaut que recoivent les tourbillons en forme de colonnes longitudinales sous l'effet des forces flottantes, dans la zone d'entree de la chaleur d'un canal horizontal a plateaux paralleles (qui est chauffe par le dessous). On a employe dans l'experience des canaux de 30 centimetres de largeur et de 2, 3 et 4.5 centimetres de hauteur. L'instabilite du mouvement de convection est produite par les effets des gradients de temperature dans le sens horizontal et le sens vertical; on l'a observee par une methode directe de visualisation de l'ecoulement basee sur la fumee. On presente des photographies des vues avant et arriere des tourbillons cylindriques. Les resultats experimentaux indiquent que le nombre d'ondes des cylindres de tourbillons demeure constant dans le sens du courant et tend a approcher la valeur theorique a mesure que le rapport entre la largeur et la hauteur du canal augmente. On a aussi observe que le nombre critique de Rayleigh provenant de la visualisation de l'ecoulement etait plus eleve de 1.4 a 10 fois que la valeur critique provenant de la theorie lineaire.

Liquid solidification in combined hydrodynamic and thermal entrance region of a circular tube

Abstract: The paper presents a theoretical and experimental investigation of liquid solidification in the combined hydrodynamic and thermal entrance region of a circular tube with a uniform wall temperature. The theoretical solution assumes that axial variations in liquid-solid interface are gradual and considers that effects of radial velocity component are significant in the entrance region. The theoretical analysis yields profiles of liquid-solid interface, pressure drop and heat transfer coefficient for the cases of Pr = 7 and 10. Experimental work using water as a working medium was carried out to verify the theoretical result by employing two double-pipe heat exchangers with a small inner tube diameter to prevent free convection effects. A series of experimental data was obtained to calculate the mean heat transfer rate. Comparison between the experimental data and the theoretical results is made. Reasonable agreement is observed. On rapporte, dans le present travail, une etude theorique et experimentale de la solidification de liquides dans le secteur d'entree a la fois hydrodynamique et thermique d'un tube circulaire dont la temperature des parois est uniforme. La solution theorique suppose que les variations axiales a l'interface liquide-solide sont graduelles et elle considere que les effets de la composante de vitesse radiale sont importants dans le sectenr d'entree. L'analyse theorique fournit des profils de l'interface liquid-solide, de la chute de prcssion et du coefficient de transfert de la chaleur dans les cas ou Pr = 7 et 10. Dans le travail experimental, on a employe l'eau comme milieu; il avait pour but de verifier le resultat theorique au moyen de deux echangeurs de chaleur deux tubes, le diametre du tube intericur etant petit afin d'empěcher les effets de la convection libre. On a obtenu un certain nombre de donnees experimentales pour calcnler le taux moyen de transfert de la chaleur. On a compare les resultats experimentaux aux donnees theoriques et observe qu'ils concordaient raisonnablement entre eux.

Theoretical frameworks for testing relativistic gravity. V. Post-Newtonian limit of Rosen's theory

Abstract: The post-Newtonian limit of Rosen's theory of gravity is evaluated and is shown to be identical to that of general relativity, except for the post-Newtonian parameter alpha sub 2 (which is related to the difference in propagation speeds for gravitational and electromagnetic waves). Both the value of alpha sub 2 and the value of the Newtonian gravitational constant depend on the present cosmological structure of the Universe. If the cosmological structure has a specific (but presumably special) form, the Newtonian gravitational constant assumes its current value, alpha sub 2 is zero, the post-Newtonian limit of Rosen's theory is identical to that of general relativity - and standard solar system experiments cannot distinguish between the two theories.

The determination of tensile properties from hardness measurements for Al-Zn-Mg alloys

Abstract: The correlations between tensile properties (yield strength, ultimate tensile strength and uniform strain) and indentation hardness are studied for two types of Al-Zn-Mg alloys. The reasons why Tabor's equations do not well fit the experimental data when the strain-hardening coefficient is larger than 0.3 are discussed. New equations for the determination of tensile properties from hardness measurements are theoretically derived and found to be in excellent agreement with the experimental data for Al-Zn-Mg alloys. The equations areT u=(H v/c 2)[4.6(m−2)] m−2 and σy=(H v/C 2)1-(3−m> ) +25 (m−2), whereT u andσ y are ultimate tensile strength and yield strength,H v is Vicker's hardness number,m is Meyer's hardness coefficient,E is Young's modulus,c 2 is a constant about 2.9 in magnitude. In these equationsT u,σ y,H v andE are all expressed in kg mm−2.

Heavy metals in drinking water in Taiwan and their possible bearing on an endemic disease.

Abstract: Heavy metals in drinking water in Taiwan have been determined by a neutron activation analysis technique The concentrations of heavy metals in different water samples vary widely, and their possible bearing on an endemic disease is discussed

Chemische Untersuchungen der Inhaltsstoffe von Pteris dispar KUNZE

Abstract: Im Zusammenfang mit der chemotaxonomischen Untersuchungen der Gattung Pteris und der verwandten Gattungen wurden aus den oberirdischen Teilen von Pteris dispar KUNZE neben der schon bekannten ent-11α-Hydroxy-15-oxo-Kaur-16-en-19-carbonsaure (III) vier neue ent-Kaurantyp-Diterpene, namlich ent-11α-Hydroxy-15-oxo-16S-Kauran-19-carbonsaure (I), ent-11α-Hydroxy-15-oxo-16R-Kauran-19-carbonsaure (II), ent-7α, 9-Dihydroxy-15-oxo-Kaur-16-en-19, 6β-olid (IV) und ent-7α, 9-Dihydroxy-15-oxo-16S-Kauran-19, 6β-olid (V), isoliert.

Chemische Untersuchungen der Inhaltsstoffe von Hypolepis punctata (THUNB.) METT.

Abstract: Aus den oberirdischen Teilen von Hypolepis punctata (THUNB.) METT. wurden neben 3 (S)-Pterosid D (V), 3 (S)-(VI) sowie 3 (R)-Pterosin D (VII) zwei neue Indan-1-on-Glukoside, d. h., 2 (R), 3 (R)-Pterosin L-2'-O-β-D-Glukosid (I) und 2 (S), 3 (R)-Pterosin L-2'-O-β-D-Glukosid (III) isoliert ; ihre Strukturen wurden aufgeklart. Durch eine Gaschromatographie-Massenspektrometrie-Analyse lasst sich das Vorhandensein von Pterosin K (VIII) nachweisen.

Binary logarithms for computing integral and non-integral roots and powers

Abstract: This paper suggests a method of utilizing binary logarithms to compute the power, root, or any exponential of a number It is an extension of Mitchell's (1962) technique Due to the approximation of the binary logarithms, there will be errors in the calculations of the results However, using this method, no logarithmic tables are required Approximations to binary logarithms are very easy to generate by simple shifting and counting Evaluating power, roots, and any exponent of a number is reduced to simple addition and subtraction operations Finally the approximation error might be reduced hy adding a fixed number to correct the binary logarithms

Structure and Function of Cobrotoxin

Abstract: In this review I describe the current status of the study of postsynaptic neurotoxins with special emphasis on the extensive studies of cobrotoxin which I started more than three decades ago. Cobrotoxin, is a neurotoxic protein isolated in crystalline state from the venom of Taiwan cobra Naja naja atra. It is a small basic protein consisting of a single peptide chain of 62 amino acid residues, crosslinked by four disulfide bonds. Cobrotoxin binds specifically to the nicotinic acetylcholine receptor on the postsynaptic membrane and thus blocks the neuromuscular transmission. The disulfide bonds and Tyr-25 which are buried in the molecule form a central core to maintain and stabilize the active conformation of the toxin. Selective and stepwise chemical modifications of cobrotoxin indicate that at least two cationic groups, an ϵ -amino group of Lys-47 and a guanidino group of Arg-33, both of which are common to all known postsynaptic snake neurotoxins, held at a certain critical distance in the molec...

On the supports and absolute continuity of infinitely divisible probability measures

Abstract: We will describe in terms of semigroups the support of an infinitely divisible probability measure ~ with no Gauss component on a separable locally compact abelian group G, and we study the absolute continuity of ~ with respect to the Haar measure k. (Gauss measures on locally compact abelian groups have been considered by Siebert [9] recently and by Urbanik D0] sometime ago.) We may assume that the measure ~ we consider has no idempotent factor, since the latter would be the Haar measure on some compact subgroup H, and the description of the support of the infinitely divisible probability measures induced on the quotient G/H would yield a complete description of the support S(~) of ~ ([4],Lemma 1.2,p.63,[ll],4.20,p.37). It is

A simple circuit of a crystal oscillator and its application to a high-resolution NMR spectrometer

Abstract: Describes a simple circuit of a crystal oscillator operating at frequencies from several megahertz to a hundred megahertz with a frequency stability of one part to 108 constructed using a dual gate MOSFET. This RF transmitter accompanied by an RF-tuned receiver can be used as a high-resolution NMR spectrometer and as a precise Gaussmeter.

Dependence of the width of a doorway state on the ratio of the numbers of the correlating and open channels

Abstract: The width $〈{\ensuremath{\Gamma}}_{d}〉$ of a doorway state, the escape width $〈{\ensuremath{\Gamma}}_{d}\ensuremath{\uparrow}〉$, the damping width $〈{\ensuremath{\Gamma}}_{d}\ensuremath{\downarrow}〉$, and the interaction $〈{V}_{d}〉$ which causes transitions from the doorway state to the more complicated states are discussed as a function of the ratio ($\frac{{n}_{d}}{n}$) between the numbers of the correlating and open channels. The results show that the widths $〈{\ensuremath{\Gamma}}_{d}〉$, $〈{\ensuremath{\Gamma}}_{d}\ensuremath{\uparrow}〉$, $〈{\ensuremath{\Gamma}}_{d}\ensuremath{\downarrow}〉$, and the interaction $〈{V}_{d}〉$ depend strongly on the square of this ratio.

Characteristics of the first excited state of 5He from the 7Li(d,αα)n reaction

Abstract: The alpha - alpha coincidence spectra from the 7Li(d, alpha alpha )n reaction were used to determine the excitation energy and width of the first excited state of 5He The results obtained were Ex=41+or-02 MeV, Gamma =44+or-02 MeV

Thermodynamic Studies on the Complexation Reactions of copper(II) Macrocyclic Tetramine Complexes with Monodentate Ligands: I. RAC‐5, 7, 7, 12, 14, 14‐Hexamethyl‐l, 4, 8, 11‐Tetraazacyclotetradecane‐Copper(II) (Blue) with‐Halide Ions

Abstract: The possibility of a trigonal bipyramidal structure for [Cu(tet b)X]+ (blue) (where X=Cl, Br, I) is supported by the observation of two distinct d-d bands, which are assigned as and d, dxyd and dxz, dyzd transitions respectively. The stability constants for the formation of [Cu(tet b)X]+ (blue) from [Cu(tet b)]z+ (blue) and X− were determined by spectrophotometric method at 25°, 35° and 45°C. The corresponding δH° and δS° values were obtained from the variations of the stability constants between 25° and 45°C

The Mass Spectral Studies of Halogenated Vinyl Methanesulfonates

Abstract: The mass spectra of saturated sulfonate esters1,2) have been reported recently. No study has been made on the vinylic methanesulfonates. In order to understand their breakdown patterns, several chloro- and fluoro-containing vinyl methanesulfonates have been made3) and their mass spectra studied. The chlorine compounds are chosen because the natural abundance of isotope 35Cl and 37Cl can serve as a internal tag. The vinyl methanesulfonates containing electronegative fluorine are used as a comparison to the chloro-compounds because of their similar electronegativities.