Phase Based Localization for Underwater Vehicles Using Interval Analysis

This paper addresses the common issue of locating an Underwater Vehicle. Usually, the positioning of a vehicle is based on the propagation of electromagnetic waves, using systems such as the Global Positioning System. However, water, and particularly salty water, makes the use of electromagnetic waves impractical due to the attenuation caused by the high conductivity of the medium. Hence, the most reliable way to transmit information underwater is by using sound waves and many technologies have emerged to solve the positioning problem in this way. Technologies such as Long BaseLine (LBL), Short BaseLine (SBL) and Ultra-Short BaseLine (USBL) are the most frequently used underwater. These technologies are based on the use of multiple emitters in the case of LBL and SBL, or multiple receivers in the case of USBL. This paper describes a way of finding a vehicle location, on-board, based on the measurement at the vehicle by a single receiver of the phase of an acoustic sine wave transmitted from a single emitter that is at a fixed and known location. The method also uses other proprioceptive measurements: vehicle’s velocity and heading. An algorithm based on contractors and bisections scatters the solution space searching for all possible solutions (positions in this case) to the set of equations. Moreover, this paper introduces the Time Constraint Satisfaction Problem. Indeed, the proposed algorithm does not compute the solutions from measurements at a single point in time, rather it uses a set of measurements taken over a time window and stored in a buffer. As a result, the location is not only known at the latest instant but the past locations can be tracked back over the length of the chosen time window.     

Simulation of electroluminescence of quantum dot-based microcavity light-emitting device

We present a detailed analysis and computations of the emitted radiation spectrum for quantum dots (QDs) microcavity light-emitting device, where the total physical thickness of the cavity spacer was kept at 254 nm which corresponds to the wavelength of the mode number (m) = 1 resonant mode of the cavity. Our calculation gives good results for QD diameter only from 1.2 to 6.4 nm. The computations are used to examine how the emitted radiation spectrum can be optimized by varying the position of the light-emitting layer, the type of cathode material, the choice of hole transport layer material, and the thickness of electron transport layer, QD layer, and hole transport layer. These studies showed that the variation of layers geometry and the position of the light-emitting layer will optimize the output intensity and the radiation spectrum and varying the ETL and QD layer thickness will have a more effect on the emitted spectrum than varying HTL thickness. In addition, we have examined the effect of using different quantum dots sizes in emission layer. On the other hand, we have investigated the difference between the electroluminescence (EL) emissions for microcavity device in comparison with the non-cavity device, and we have found that the full width at half maximum (FWHM) of the EL is reduced from 45 nm for the QD non-cavity LED to 30 nm for the output of a resonant microcavity device. Finally, we have investigated the compatibility between our calculation and the experimental results and found a fairly good agreement between them.     

On Condensation Reactions of Aceanthrene Quinone: Novel Heterocycles

Summary.  It was found that aceanthrene quinone can be condensed with ethylenediamine, 1,2-diaminobenzene, 4-nitro-1,2-diaminobenzene, 1,2-diaminoanthrene quinone, and 4,5,6-triaminopyrimidine derivatives to give aceanthryleno[1,2-b]pyrazine and aceanthryleno[1,2-g]pteridine derivatives. Condensation of aceanthrene quinone with 2-aminoguanidine, semicarbazide, and thiosemicarbazide yielded aceanthryleno[1,2-e]triazines, condensation with 6-hydrazinopyrimidine derivatives gave 3,4-aceanthrylenopyrimido[4,5-c]pyridazines. Reaction of aceanthrene quinone with 2-cyanoethanoic acid hydrazide afforded 10,11-dihydro-10-oxo-aceanthryleno[1,2-c]pyridazine-9-carbonitrile. Treatment of aceanthrene quinone with malononitrile and hydrazine hydrate resulted in 10-aminoaceanthryleno[1,2-c]pyridazine-9-carbonitrile. The antibacterial effects of the prepared compounds were tested. Three of the compounds were tested against 60 cancer types. Received May 6, 2001. Accepted June 5, 2001     

Synthesis of substituted pyrazolo [1,5 — a] pyrimidines

Condensation of 3-amino-4-cyanopyrazole (1) with ethylacetoacetate, ethyl cyanoacetate, diethyl malonate and acetylacetone afforded pyrazolo[1,5-a]pyrimidine derivatives (2—8a). Other compounds (8b—h) of this ring system were obtained by treatment of 1 with arylidenemalononitrile and ethylarylidenecyanoacetate. And the reaction of compound (1) with activated acetylenes yeilded pyrazolo[1,5-a]pyrimidine derivatives (11a—b).     

Influence of γ-irradiation on the optical and electrical properties of Se(0.85) Te(0.15) films

Abstract

Se_(0.85) Te_(0.15) films were prepared by thermal evaporation under vacuum on glass substrate. The optical and electrical properties of as deposited and irradiated Se_(0.85) Te_(0.15) films with different γ-doses are reported.

The optical constants (absorption coefficient (α), extinction coefficient (k), refractive index (n) and dielectric constants (?, ?) of unirradiated and irradiated films were calculated. The value of allowed direct optical energy gap of Se_(0.85) Te_(0.15) films increased from 1.47 eV. to 1.72 eV. with increasing the γ-doses to 2.5 Mrad. The irradiated films have lower resistivity than those as deposited films (unirradiated). The activation energy (ΔE) increases from 0.72 eV. to 0.86 eV. with increasing γ-doses to 2.5 Mrad.     

Goniothalenol: a novel,bioactive, tetrahydrofurano-2-pyrone from goniothalamus giganteus (annonaceae)

Fractionation of the stem bark of the title plant, monitoring for bioactivity with brine lethality, led to the isolation of goniothalenol (I). Mass, ¹HNMR, and ¹³CNMR spectral data helped to characterized I as a phenyltetrahydrofurano-2-pyrone, as a novel heterocyclic ring system for natural compounds. X-Ray crystallographic analysis confirmed the structure and established the configuration for I.     

Setting Job-Shop Due-Dates with Service-Level Constraints

The job-shop due-date assignment problem arises when a manager needs to ‘promise’ a delivery date to a customer. Previous methods yield due-dates which are either optimistic (unlikely to be achieved) or conservative (the promise will be met, but too easily, because the date given was very pessimistic). This paper investigates the due-date assignment problem with a customer ‘service-level’ constraint, the percentage of time that promised delivery dates are honoured. We formulate a rule to attain this service level, yet maintain as short a due-date lead time as possible. Unlike previous attempts, this due-date rule considers not only the job content and instantaneous shop congestion information, but also implicitly incorporates information on how the jobs will be scheduled (or ‘loaded’) once they are in the shop. We simulate a single-machine shop for various measures of performance under several dispatching priorities, comparing our due-date rule with one reported to yield satisfactory performance. Our rule meets all requirements and is found to be superior for most measures of performance.     

Biotransformation of phorbol by human intestinal bacteria

Anaerobic incubation of phorbol (1) from Croton tiglium with human intestinal bacteria afforded five metabolites: isophorbol (2), deoxyphorbol (3), 4beta,9alpha,20-trihydroxy-13,15-seco-1,6,15-tigliatriene-3,13-dione (4), 4beta,9alpha,20-trihydroxy-15,16,17-trinor-1,6-tigliadiene-3,13-dione (5) and 4beta,9a,20-trihydroxy-14(13-->12)-abeo-12alphaH-1,6-tigliadiene-3,13-dione (6). All these metabolites (2-6) were identified and characterized by spectroscopic means, including two-dimensional (2D)-NMR. Nine defined strains from the human intestine showed an ability to transform 1 to these metabolites.     

The Stabilities of the o-Carboxyphenylhydrazo-Ethylacetoacetate OF Cu,Ni, Co,Zn, Mn and Cd Chelate Compounds in Different Solvents

The dissociation constants for o-carboxyphenylhydrazoethylacetoacetate (o-CPHEA) ligand, as well as the stability constants for the divalent metal complexes of Cu, (II), Ni (II), Co (II), Zn (II)and Cd (II) ions, have been calculated pH-meterically in different solvents. The dissociation constans pK₁=4.10 and pK₂=10.55 of the insoluble organic ligand are calculated in aqueous medium. The effect of solvents, the relation between stabilities and both electronegativities and ionization potential are studied.     

Synthesis and Inhibitory Effect of Some Indole-Pyrimidine Based Hybrid Heterocycles on α-Glucosidase and α-Amylase as Potential Hypoglycemic Agents

The Michael addition reaction of barbituric acid with chalcones incorporating the indole scaffold was achieved by using a highly efficient bimetallic Iron–palladium catalyst in the presence of acetylacetone (acac). This catalytic approach produced the desired products in a simple operation and low catalyst loading with acceptable yield of the new hybrids. All tested compounds were subjected for biological activity on α-glucosidase and α-amylase. The results revealed that all synthesized compounds exhibited very good activity against both enzymes when compared to positive control (acarbose). Moreover, compound 5o showed the best activity whereas its IC₅₀ (μM) are 13.02+0.01 and 21.71+0.82 for α-glucosidase and α-amylase respectively. Both compounds 5o and 5l exhibited high similarity in binding mode and pose with amylase protein (4UAC). The obtained data may be used for developing potential hypoglycemic agents.