BP neural network recognition algorithm for scour monitoring of subsea pipelines based on active thermometry

Scour monitoring is an important concern for subsea pipeline systems. The active-thermometry-based scour monitoring is based on the difference of heat transfer properties between sediment and sand, recognizes the surrounding media though temperature changing patterns during heating and cooling processes, and hence detects the free spans. Based on the scour monitoring system, a two-layer BP neural network was employed to process the monitoring data and achieved media recognition. The network's inputs were normalized temperature time histories. The network's outputs denoted different media: sediment and water. To validate the method, three experiments were conducted; one was used for training the network and the other two for testing. Also, the effect of noise on the network's performance was studied through simulation. The results demonstrated the feasibility and robustness of the neural network.     

ORGANISCHE PHOTOCHEMIE XXXII1,2

Abstract

Es werden drei neue Beispiele zu Photoreaktionen von Aroyl-diphenylphosphinen beschrieben, die sowohl unter α-Spaltung als auch 1.2-Sauerstoff-Transfer aus der Carbonylgruppe auf den Phosphor verlaufen. Beide Reaktionen finden auch im Massenspektrometer statt.

Three new examples to photoreactions of aroyl diphenyl phosphines which undergo α-cleavage as well as 1.2-oxygen transfer from the carbonyl group onto the phosphorous atom are described. Both reactions also occur in the mass spectrometer.     

All-optical active components for dielectric-loaded plasmonic waveguides

Dielectric-loaded surface plasmon polariton waveguides (DLSPPWs) provide a very efficient means to localize and guide optical signal, which makes them a promising candidate for the construction of highly-integrated photonic circuits. Here, we present full 3D numerical modelling of highly efficient and compact all-optical active DLSPPW components to achieve a fully functioning active photonic circuit.     

Syntheses of Optically Active Polyacrylates

ABSTRACT

Different secondary alcohols were resolved by lipase catalyzed transesterification using 2,3-butanedione monoxime acrylate as acrylating agent. The results showed that the reaction rates were the fastest among reactions reported until now. The effect of solvent on the transesterification rate was studied. The enantiomeric excess (ee) and enantiomeric purity (E value) of all the acrylate monomers were determined. The synthesized optically active acrylate monomers were polymerized by free radical polymerization technique.     

A Mild and Versatile Method for the Tetrahydropyranylation of Alcohols and Their Detetrahydropyranylation

An efficient and mild method for tetrahydropyranylation of alcohols and their detetrahydropranylation using NH₄Cl is described. This protocol provides a useful alternative tetrahydropyranylation of alcohols and their deprotection at different pH.

     

1,4-Diazabicyclo[2.2.2]octane as an Efficient Catalyst for a Clean,One-Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives via Multicomponent Reaction in Aqueous Media

1,4-Diazabicyclo[2.2.2]octane (DABCO) has been used as a mild and efficient catalyst for the synthesis of various tetrahydrobenzo[b]pyran derivatives via a one-pot, three component condensation of aromatic aldehydes, dimedone, and active methylene compounds. This method provides several advantages: a simple workup procedure, environmental friendliness, neutral conditions, and good yields. In addition, water or 50% aqueous ethanol was chosen as a green solvent.

A Simple,Efficient and Green Procedure for the Knoevenagel Condensation of Aldehydes with N-Methylpiperazine at Room Temperature under Solvent-Free Conditions

Knoevenagel condensation of aromatic, aliphatic, and heteroaromatic aldehydes with active methylene compounds such as ethylcyanoacetate, malononitrile, and cyanoacetamide proceed very smoothly at room temperature by simply mixing the ingredients together under solvent-free conditions in the presence of N-methylpiperazine in excellent yields of the E-configured products.     

A Mild and Efficient Route to 3-Vinylchromones in Aqueous Micellar Media

A simple, mild, and ecofriendly method has been developed for the synthesis of 3-vinylchromones from 4-oxo-4H-1-benzopyran-3-carboxaldehyde (3-formylchromone) by simple Knoevenagel condensation with various active methylene compounds (AMC) in aqueous micellar media in the presence of catalytic amounts of cetyl trimethylammonium bromide (CTAB) and 1,4-diazabicyclo[2.2.2]octane (DABCO). In the case of malonic acid as AMC, the reaction resulted in formation of only Doebner decarboxylated products under the standard reaction condition. It has been also observed that 3-formylchromone derivatives primarily undergo tandem Knoevenagel and Michael reactions in the presence of > 2 equiv. of ethyl acetoacetate to produce benzophenone derivatives, by opening of pyran ring, as the sole product in good yields.     

A Method for Determination of Low Levels of Exposure to 2,4-D and 2,4,5-T

A method has been developed for the determination of trace quantities of 2,4-dichloro-phenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), 2,4-dichlorophenol (2,4-DCP), and 2,4,5-trichlorophenol (2,4,5-TCP) in human and rat urine. The method involves acid hydrolysis of the phenolic conjugates, extraction of the free phenols and acids, ethylation with diazoethane, silica-gel column chromatography clean-up of the derivatized urine extract, and gas chromatographic determination using the electron-capture detector. The average recoveries of 2,4-D, 2,4,5-T, 2,4-DCP, and 2,4,5-TCP from rat urine spiked with known amounts of the herbicides and their phenols were 94%, 98%, 92%, and 90%, respectively. The limits of detection for 2,4-D, 2,4,5-T, DCP, and TCP in rat urine were: 0.05, 0.01, 0.10, and 0.01 ppm, respectively. The method was used to analyze urine of rats given various levels of 2,4-D and 2,4,5-T by gavage. Results showed that levels of exposure of 3.75 mcg/kg for 2,4-D and 5.0 mcg/kg for 2,4,5-T in rats can be detected in urine within 24 hr from exposure. Urine samples from occupationally exposed people were analyzed and found to contain 0.2 to 1.0 ppm 2,4-D and 0.05 to 3.6 ppm 2,4,5-T.