Showing papers by "Polytechnic University of Valencia published in 1994"
TL;DR: The results show that the new version of the AESA, referred to as ‘Linear AESA’ (LAESA), achieves a search performance similar to that of the ASIC, while definitely overcoming the quadratic costs bottleneck.
337 citations
TL;DR: In this paper, a hydrodynamic mechanism has been proposed and experimentally analyzed for the modeling of the vacuum osmotic dehydration operation, taking this new mechanism into account, a more accurate approach to the modelling of the ODE operation may be done.
335 citations
TL;DR: An efficient algorithm is proposed to find M points, among those given, which define a polygonal curve that is a globally optimal approximation to the given points.
234 citations
15 Aug 1994
TL;DR: A partially adaptive routing algorithm for k-ary n-cubes which doubles the throughput without increasing the hardware complexity significantly and is the key for the design of maximally adaptive routing algorithms with minimum restrictions.
Abstract: Deadlock avoidance is a key issue in wormhole networks. A first approach [8] consists of removing the cyclic dependencies between channels. Although this is a necessary and sufficient condition for deadlock-free deterministic routing, it is only a sufficient condition for deadlock-free adaptive routing. A more powerful approach [12] only requires the absence of cyclic dependencies on a connected channel subset. The remaining channels can be used in almost any way. In this paper, we propose a necessary and sufficient condition for deadlock-free adaptive routing. This condition is the key for the design of maximally adaptive routing algorithms with minimum restrictions. Some examples are given, showing the application of the new theory. In particular, we propose a partially adaptive routing algorithm for k-ary n-cubes which doubles the throughput without increasing the hardware complexity significantly.
215 citations
TL;DR: In this article, the non-diffusional mass transfer in operations where porous food is immersed in a liquid and submitted to vacuum conditions is analyzed, and the liquid penetration in the food pores due to pressure gradients have been mathematically modelled.
196 citations
TL;DR: In this article, the effect of shrinkage, heat transfer and particle temperature variation during drying, and the De dependence on moisture and temperature simultaneously were considered for the description of convective drying of vegetables.
145 citations
TL;DR: The latter process was found to mediate the photoperoxidation of linoleic acid through a type I mechanism, as evidenced by the inhibition produced by the radical scavengers butylated hydroxyanisole and reduced glutathione.
Abstract: Irradiation of ketoprofen in neutral aqueous medium gave rise to 3-ethylbenzophenone as the major photoproduct. Its formation is justified via protonation of a benzylic carbanion or hydrogen abstraction by a benzylic radical. Minor amounts of eight additional compounds were isolated. Four of them are derived from the benzylic radical: 3-(1-hydroperoxyethyl)benzophenone, 3-(1-hydroxyethyl)benzophenone, 3-acetylbenzophenone and 2,3-bis-(3-benzoylphenyl)butane. The other four products involve initial hydrogen abstraction by the excited benzophenone chromophore of ketoprofen: 1,2-bis-(3-ethylphenyl)-1,2-diphenyl-1,2-ethanediol, 2-(3-benzoylphenyl)-1-(3-ethylphenyl)-1-phenylpropan-1-ol, alpha-(3-ethylphenyl)phenylmethanol, 1,2-bis-[3-(2-hydroxycarbonylethyl) phenyl]-1,2-diphenyl-1,2-ethanediol. The latter process was found to mediate the photoperoxidation of linoleic acid through a type I mechanism, as evidenced by the inhibition produced by the radical scavengers butylated hydroxyanisole and reduced glutathione. The major photoproduct, which contains the benzophenone moiety but lacks the propionic acid side chain, also photosensitized linoleic acid peroxidation. Because lipid peroxidation is indicative of cell membrane lysis, the above findings are highly relevant to explain the photobiological properties of ketoprofen.
138 citations
21 Sep 1994
TL;DR: This paper revisits the theory of regular inference by extending the definition of structural completeness of a positive sample and by demonstrating two basic theorems, which enables to state the regular inference problem as a search through a boolean lattice built from the positive sample.
Abstract: This paper revisits the theory of regular inference, in particular by extending the definition of structural completeness of a positive sample and by demonstrating two basic theorems. This framework enables to state the regular inference problem as a search through a boolean lattice built from the positive sample. Several properties of the search space are studied and generalization criteria are discussed. In this framework, the concept of border set is introduced, that is the set of the most general solutions excluding a negative sample. Finally, the complexity of regular language identification from both a theoritical and a practical point of view is discussed.
118 citations
TL;DR: In this paper, the flow and heat transfer of an incompressible second-order fluid past a stretching sheet using Dandapat and Gupta's boundary layer solution is studied.
Abstract: This paper presents a study of the flow and heat transfer of an incompressible second-order fluid past a stretching sheet using Dandapat and Gupta's boundary layer solution. Two cases are studied, namely, (i) the sheet with constant surface temperature (CST case) and (ii) the sheet with prescribed surface temperature (PST case). The solutions for the temperature and the heat transfer characteristics for large Prandtl number (σ) are obtained using a Runge-Kutta method of fourth order with step size Δz = 0.01.
103 citations
TL;DR: In this article, the authors compared the activity, selectivity, and decay behavior of SO2−/ZrO2 (SZ) and zeolite Beta (Hβ) catalysts for two acid catalyzed demanding reactions, i.e., the isomerization of n-butane, and the alkylation of isobutane with 2-butene.
Abstract: The activity, selectivity, and decay behavior of SO2−/ ZrO2 (SZ) and zeolite Beta (Hβ) catalysts are compared for two acid catalyzed demanding reactions, i.e., the isomerization of n-butane, and the alkylation of isobutane with 2-butene. The superacidity present in the SZ sample makes this catalyst active for both reactions at lower temperatures than the zeolite. For the isomerization of n-butane the reaction pathway leading to isobutane was seen to be different for both catalysts. A similar decay behavior was observed on the two catalysts, but the SZ sample gave a much higher selectivity to isobutane. For the alkylation reaction, the SZ catalyst is much more selective to TMP's than Hβ at low reaction temperatures. The lower selectivity to TMP's obtained on Beta zeolite is mainly due to the formation of DMH's by dimerization of butenes, while undesirable cracking reactions leading to C5-C7 products occur to a higher extent on the superacid SZ catalyst. The latter deactivates much faster than the zeolite. The acid strength distribution, and hydrogen transfer activity were seen to determine the changes in product distribution with time-on-stream obtained on both catalysts.
100 citations
TL;DR: The facial structure of this unbounded full-dimensional polyhedron is tried to characterize and sets of valid inequalities inducing facets have been studied as well as their use in a cutting-plane algorithm.
TL;DR: A new development of the AESA is presented which formally adheres to the general algorithmic strategy of (best-first) Branch and Bound (B&B) and naturally suggests a new selection or Approximating Criterion which is cheaper to compute.
16 May 1994
TL;DR: This work proposed a necessary and sufficient condition for deadlock-free adaptive routing, and proposed a more powerful approach that only requires the absence of cyclic dependencies on a connected channel subset.
Abstract: Deadlock avoidance is a key issue in wormhole networks. A first approach [9] consists in removing the cyclic dependencies between channels. Although the absence of cyclic dependencies is a necessary and sufficient condition for deadlock-free deterministic routing, it is only a sufficient condition for deadlock-free adaptive routing. A more powerful approach [12] only requires the absence of cyclic dependencies on a connected channel subset. Moreover, we proposed a necessary and sufficient condition for deadlock-free adaptive routing [15].
TL;DR: In this article, the continuous alkylation of isobutane with 2-butene was carried out on a series of beta catalysts prepared by two different synthesis procedures, involving the use of amorphous silica (Aerosil) and TEOS as silica source.
Abstract: The continuous alkylation of isobutane with 2-butene was carried out on a series of beta catalysts prepared by two different synthesis procedures, involving the use of amorphous silica (Aerosil) and TEOS as silica source. The stability of the zeolite towards dealumination during the activation steps was seen to increase with Si/Al ratio and crystal size of the beta catalyst. The most stable catalysts were also the most active and selective for alkylation, giving a higher TMP/DMH ratio during the initial reaction stages. These samples also deactivate at a lower rate with TOS. The observed differences in catalytic activity and selectivity were attributed to differences in both total acidity and acid strength distribution. Finally, the influence of reaction temperature and isobutane/2-butene ratio on the catalytic behavior were also investigated.
TL;DR: The catalytic behavior of the MCM-22 zeolite for the continuous alkylation of isobutane with 2-butene has been investigated at a temperature of 50°C, 25 MPa total pressure, and a variety of olefin space velocities.
Abstract: The catalytic behavior of the novel MCM-22 zeolite for the continuous alkylation of isobutane with 2-butene has been investigated at a temperature of 50°C, 25 MPa total pressure, and a variety of olefin space velocities At high olefin conversions the MCM-22 zeolite showed a very high initial cracking activity attributable to strong Bronsted acid sites, as well as to the existence of strong diffusional restrictions of the TMP's (formed inside the zeolite) to exit through the channels At short times on stream (TOS), TMP's account for ca 40% of the C8 fraction The olefin conversion and the cracking activity rapidly decline with TOS, while the alkylate product became richer in dimethylhexenes, indicating a predominance of 2-butene dimerization and a loss of hydrogen transfer activity as the catalyst aged Moreover, MCM-22 gives less TMP's than large-pore zeolites (USY, beta, mordenite), but more than the mediumpore ZSM-5 at similar 2-butene conversion The latter catalyst was much more selective for olefin dimerization than for isobutane alkylation, presumably because formation of the bulkier TMP's was strongly impeded in its smaller pores
TL;DR: In this paper, an algorithm to calculate the 3D harmonic lambda modes corresponding to the steady state two-group 3D neutron-diffusion equation is presented, which uses subspace iteration method techniques combined with convergence acceleration based on variational principles.
TL;DR: In this paper, the hydrotalcite catalyst was optimized from the point of view of its textural properties, composition, and Al/(Al+Mg) in the case of the magnesium-aluminium hydroalcites, and influence of water, reaction temperature and polarity of the solvent on conversion and selectivity was studied.
Abstract: Citronitril was obtained starting from ethyl cyanoacetate and benzylacetone using solid base catalysts. Hydrotalcites were found to carry out this reaction efficiently. The hydrotalcite catalyst was optimized from the point of view of its textural properties, composition ,i.e. Ca, Mg, and Zn as divalent cations, and Al/(Al+Mg) in the case of the magnesium-aluminium hydrotalcites. The influence of water, reaction temperature and polarity of the solvent on conversion and selectivity was studied.
TL;DR: In situ hybridization experiments were carried out to detect avocado sunblotch viroid (ASBVd) in foliar tissue of avocado, using a digoxigeninlabelled RNA probe complementary to the ASBVD-RNA in sections of aldehyde-fixed, LRGold-embedded leaf samples.
Abstract: In situ hybridization experiments were carried out to detect avocado sunblotch viroid (ASBVd) in foliar tissue of avocado, using a digoxigeninlabelled RNA probe complementary to the ASBVd-RNA in sections of aldehyde-fixed, LRGold-embedded leaf samples. Detection of the probe was made through anti-digoxigenin antibody and protein-A colloidal gold (20 nm). Seventy to 80% of the signals came from chloroplast while the cytoplasm and vacuole were labelled with ca. 10% of the gold particles. This is in contrast with the subcellular localization of potato spindle tuber viroid and some other related viroids, which are mainly found in the nucleus.
TL;DR: In this article, a study of two simple quantum mechanical systems, i.e., harmonic oscillator (HO) and hydrogen atom (H) trapped inside the well is performed, and the influence of the spatial confinement on the energy spectra of both systems is investigated.
Abstract: A study of two simple quantum mechanical system, i.e., harmonic oscillator (HO) and hydrogen atom (H) trapped inside the wells is performed. The influence of the spatial confinement on the energy spectra of both systems is investigated. An analytically solvable model of the well potential is presented in the case of the HO. A central and noncentral localization of HO in the well is discussed. The results are used to explain some reported anomalous experimental data on the porphine IR spectrum. The case of hydrogen atom is studied by solving the problem of the electron in the potential V = Z/R cot r/R. An exact formula for the energy is derived for s states. For others, analytically nonsolvable symmetries, a formula with correct asymptotic behavior is proposed. The results are compared with some numerical calculations for spherical rectangular well and an extension to many-electron atoms is also presented. The effect of breaking degeneracy and of ordering energies of H in a different way than in the case of many-electron systems is broadly discussed. © 1994 John Wiley & Sons, Inc.
TL;DR: It is observed that the pH-dependence behavior is different for Pb(II) and Fe(III) compared to the other metal ions, which indicates that between pH 6.0 and 7.5 a variety of metal ions bind strongly to the cell surface.
Abstract: The yeast Saccharomyces cerevisiae was covalently immobilized on controlled pore glass (CPG) using a modified method of enzyme immobilization. This species was packed in a mini-column and incorporated in a flow injection manifold system for trace determination of some metals prior to quantification with atomic absorption spectrometry (AAS). A number of investigations on the ability of the microorganism to remove metal ions from solution have shown that different metal ions bind to the cell wall of yeast. We have observed that the pH-dependence behavior is different for Pb(II) and Fe(III) compared to the other metal ions. Between pH 6.0 and 7.5 a variety of metal ions bind strongly to the cell surface. All the metal ions tested were deabsorbed by lowering the pH to < 2.0. Samples of 5 mL of Cd(II), Zn(II), Cu(II), Pb(II), and Fe(III) were preconcentrated to give detection limits of 0.2, 0.1, 0.7, 8.0, and 0.6 ng/mL, respectively. The analysis of real sample reference material showed a good agreement with the certified values for cadmium and copper.
TL;DR: The DU dam genes in the BL sired pigs improved overall acceptability of the ham with respect to BL × (LR × LW), classified as the poorest ham.
TL;DR: Comparative studies of this gene and a related basic isoform ofPR-1 indicate that the expression of these two members of the PR-1 gene family in tomato may be differentially regulated upon viroid infection.
Abstract: A Lycopersicon esculentum cDNA clone encoding an acidic-type pathogenesis-related protein (PR-1a1) was isolated, sequenced and characterized. It contains an open reading frame of 175 amino acids and the mature protein, after cleavage of the 21 amino acid signals peptide, has a pI of 5.24. The protein shows highest homology (75% identity) with the basic pathogenesis-related prb-1b protein from tobacco. The PR-1a1 gene shows constitutive expression in roots from tomato plants. It is expressed in leaves and stems upon viroid infection, and appears to be induced by ethylene. Comparative studies of this gene and a related basic isoform of PR-1 indicate that the expression of these two members of the PR-1 gene family in tomato may be differentially regulated upon viroid infection.
TL;DR: In this article, a series of magnesium-rich Mg-Al spinels were prepared from hydrotalcites and characterized, and different transition metal oxides were tried as co-catalysts, and among them CuO, showed excellent properties to catalyze SO2 oxidation as well as catalyst regeneration.
Abstract: A series of magnesium-rich Mg-Al spinels were prepared from hydrotalcites and characterized. When CeO2 was incorporated they showed a very good SOx absorption as FCC SOx additives, but their regeneration capacity was limited. Different transition metal oxides were tried as co-catalysts, and among them CuO, showed excellent properties to catalyze SO2 oxidation as well as catalyst regeneration. The SOx catalyst was stable when steamed at 750°C together with FCC catalysts.
TL;DR: In this article, three dinuclear complexes of formula [Cu(pdmg)Ni(cyclam)](ClO 4 ) 2 ·H 2 O (3) (H 2 pdmg=3,3′-aminopropylenedinitrilobis(2-butanoneoxime); bipy=2,2′-bipyridyl; terpy=2
TL;DR: In this paper, the authors employed thermal sampling and partial heating techniques to experimentally analyze the observed complex relaxation processes, due to the secondary (βsw) and the main (α) relaxation, into approximately single responses and to determine the spectra of activation energies E(T) at different h values.
Abstract: Detailed investigations on the dielectric relaxation mechanisms in poly(hydroxyethyl acrylate) (PHEA), by means of the thermally stimulated depolarization currents (TSDC) method in the temperature range 77-300 K are reported. There is particular interest in the dependence of the dielectric relaxation mechanisms on the water content h, h = 0 − 0.5 w/w, in an attempt to contribute to a better understanding of the physical structure of water in the PHEA hydrogels. We employ thermal sampling (TS) and partial heating (PH) techniques to experimentally analyze the observed complex relaxation processes, due to the secondary (βsw) and the main (α) relaxation, into approximately single responses and to determine the spectra of activation energies E(T) at different h values. Measurements with different electrode configurations reveal different aspects of the dynamics of the relaxation mechanisms and allow the distinction between dipolar and conductivity relaxation contributions. It is shown that by means of these techniques we can determine certain temperature characteristics for the α relaxation and investigate their dependence on water content. We discuss the relation of these characteristic temperatures to the calorimetric glass transition temperature Tg. © 1994 John Wiley & Sons, Inc.
TL;DR: Evaluating the use of unilateral ovariectomy for the measurement of uterine capacity in rabbits through a comparison of the relationships between ovulation rate, number of implanted embryos, and litter size found that pre- and postimplantation survivals were not related in intact does but seemed to be related in ULO does through an effect on the number of implantation sites.
Abstract: A study was performed to evaluate the use of unilateral ovariectomy for the measurement of uterine capacity in rabbits through a comparison of the relationships between ovulation rate, number of implanted embryos, and litter size in unilaterally ovariectomized (ULO) and intact does. Data from 211 ULO and 323 intact does were analyzed. The animals were derived from a synthetic line previously selected on litter size. Laparoscopy was performed on all does during their second gestation 12 d after mating and the number of corpora lutea and implantation sites were recorded. Intact and ULO does had the same ovulation rate, confirming the presence of compensatory ovarian hypertrophy in the remaining ovary of the ULO does. The number of implantation sites in the ULO group (11.3) approached the number found in the control group (12.6). Embryonic survival (until implantation) was lower (P < .01) in ULO does (.77) than in intact does (.88), but fetal survival (after implantation) was the same in both groups. The ULO females produced litters 77% of the size of those of the normal control females. Pre- and postimplantation survivals were not related in intact does but seemed to be related in ULO does through an effect on the number of implantation sites. The coefficient of the regression of number of implantation sites on ovulation rate was positive in control does (.62 +/- .06) and was also positive in ULO does (.31 +/- .07), showing that a higher ovulation rate would have resulted in a higher number of embryos being implanted in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: A comparative study of a representative sample of packages: CA-Superproject, Instaplan, Micro Planner, Microsoft Project and Project Scheduler is presented, through the evaluation of quality features such as user-friendliness, documentation, resource allocation.
TL;DR: In this article, the effects of lithium bromide (LiBr) concentration, pH, temperature, exposure time, and the action of some inhibitors on corrosion of several carbon (C) steels, stainless steels (SS), and a titanium (Ti) alloy were studied.
Abstract: Effects of lithium bromide (LiBr) concentration, pH, temperature, exposure time, and the action of some inhibitors on corrosion of several carbon (C) steels, stainless steels (SS), and a titanium (Ti) alloy were studied. Corrosion rates were determined by the polarization resistance method and compared to rates determined by weight-loss measurements. Pitting potentials (Ep) were evaluated in neutral LiBr solution and with different inhibitors. Pit density and average pit depth depended on the metal tested, with lowest values for Ti, the next lowest values for type 316 SS (UNS S31600), and the highest values for UNS G41350 tempered steel.
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TL;DR: In this paper, the basic criteria for mapping are usually chosen according to flood return periods, sometimes, the expected water depth or dynamic considerations are used instead, and these criteria are discussed on mapping examples from several countries.
Abstract: Flood risk maps are the essential tools for land use planning in flood-prone areas. The basic criteria for mapping are usually chosen according to flood return periods. Sometimes, the expected water depth or dynamic considerations are used instead. These criteria are discussed on mapping examples from several countries. To draw a flood risk map, four phases are usually recognized: hydrologic, geomorphic, hydraulic and land use. Each of these phases poses different problems and requires relevant methodologies to accomplish them. As an example, the program for flood risk mapping of the Valencia Region in Spain is presented. A flood risk map is considered as a preliminary yet necessary initial step for all regional development policies.
TL;DR: Two complementary DNA clones corresponding to new β-1,3-glucanases from tomato plants which are expressed upon challenge with citrus exocortis viroid are isolated and characterized, indicating that they are part of a general and coordinate mechanism of response of tomato plants susceptible to viroid infection.
Abstract: β-1,3-glucanases are hydrolytic enzymes considered to constitute part of the general array of defense genes induced by pathogen infection in higher plants. We have isolated and characterized two complementary DNA clones, corresponding to new β-1,3-glucanases from tomato plants (Lycopersicon esculentum) which are expressed upon challenge with citrus exocortis viroid. Amino acid sequence comparison revealed that they are most similar to β-1,3-glucanases from tobacco, particularly to PR-Q′, the unique component of the class III β-1,3-glucanase. The deduced amino acid sequences of the two tomato β-1,3-glucanases indicate that, although being highly similar in amino acid sequence, they have different isoelectric points: pI 10.5 for the basic isoform (Tom PR-Q′ b) and pI 5.2 for the acidic one (Tom PR-Q′ a). The expression of these two β-1,3-glucanase messenger RNAs (mRNAs) in response to viroid infection and ethephon treatments was examined. mRNAs for these two isoforms are coordinately expressed and induced similarly to mRNAs for other PR proteins, indicating that they are part of a general and coordinate mechanism of response of tomato plants susceptible to viroid infection.