Formation of dynamic virtual enterprises and enterprise networks

This paper addresses the preparation and set up of virtual enterprises and enterprise networks. A virtual enterprise (VE) can be perceived as a customer solution delivery system created by a temporary and re-configurable information and communications technology (ICT) enabled aggregation of competencies. The main achievements of the research include: (1) Clarification and definition of the concept for virtual enterprises and enterprise networks including preparation of these. (2) Development of a framework and a reference architecture for virtual enterprises named as Structured Methodology and ICT Reference Architecture respectively. Structured methodology structures the body of knowledge related to preparation, setup, and operation of virtual enterprises and enterprise networks. ICT reference architecture consists of three levels with seven layers to portray in a diagrammatic fashion how different enterprises may exchange and use information between their respective organizations’ specific proprietary systems and a central server. (3) Development of a methodology for virtual enterprise named as virtual enterprise methodology (VEM). VEM consists of a set of guidelines, which systematically describes activities that enterprises should consider in relation to set up and preparation of own enterprise networks with the aim to set up virtual enterprises. (4) Testing and validation of the developed VEM with the realization of a virtual case study. Virtual case study demonstrates and validates the application of the developed VE methodology with the illustration of the key activities related to setting up breeding environment, setting up and operating VE and dissolution of VE.     

Energy efficiency in pumps

In this paper, “energy efficiency” studies, done in a big industrial facility’s pumps, are reported. For this purpose; the flow rate, pressure and temperature have been measured for each pump in different operating conditions and at maximum load. In addition, the electrical power drawn by the electric motor has been measured. The efficiencies of the existing pumps and electric motor have been calculated by using the measured data.

Potential energy saving opportunities have been studied by taking into account the results of the calculations for each pump and electric motor. As a conclusion, improvements should be made each system. The required investment costs for these improvements have been determined, and simple payback periods have been calculated.

The main energy saving opportunities result from: replacements of the existing low efficiency pumps, maintenance of the pumps whose efficiencies start to decline at certain range, replacements of high power electric motors with electric motors that have suitable power, usage of high efficiency electric motors and elimination of cavitation problems.     

Response to thermal exposure of the mechanically alloyed Al–Ti/C powders

Al–TiC_p composites have been extensively studied in recent years not only because of their attributes as wear-resistant structural materials but also on account of their potential as very efficient grain refiners. Al–Ti–C alloys of various compositions have already been commercialized as grain refining master alloys and have long been in use in aluminium foundries world wide. The present work was undertaken to investigate the possibility of manufacturing Al–TiC_p grain refiner master alloy tablets by the mechanical alloying route. Carbon was mechanically alloyed into Al–Ti alloy powder grains via high energy ball milling. The Al–Ti/C powder blend thus obtained was heat treated to promote the precipitation of TiC. Al₄C₃ was the first phase to form inside the powder grains upon thermal exposure. The Al₄C₃ particles which were too small to be identified with the optical microscope until 750 °C, have grown until 850 °C where they have started to react with Al₃Ti to produce TiC. A very fine dispersion of TiC particles was thus generated inside the powder particles while the Al₃Ti phase has almost vanished.     

Electrochemical,continuous-flow determination of p-benzoquinone on a gold nanoparticles poly(propylene-co-imidazole) modified gold electrode

A novel continuous flow biosensor based on gold nanoparticles and poly(propylene-co-imidazole) was developed for the online determination of p-benzoquinone. The amperometric response was measured as a function of p-benzoquinone concentration at an applied potential of ?50 mV. The hydrogen peroxide concentration was optimized and fixed at 1 mM in samples. The mass transfer resistance of the copolymer film was minimized, and the flow cell was regenerated quickly at 1 mL/min. The resulting device provided good analytical performance based on a linear dynamic range from 5–100 µM, a short response time of 3 s, a detection limit of 3.3 µM, excellent repeatability with a relative standard deviation of 0.82%, long-term stability of 95% after four weeks, and an accuracy of 105%. The gold nanoparticles enhanced the electron transfer rate on the electrode. The apparent Michaelis-Menten constant was 4 mM, showing that the enzyme retained catalytic specificity and provided high activity for p-benzoquinone.     

Different Hemi-Salen/Salan Ligand Containing Binuclear Boron-Fluoride Complexes: Synthesis,Spectroscopy, Fluorescence Properties,and Catalysis

A family of hemi-salen (L₁H–L₆H) and hemi-salan (L_1aH–L_2aH) ligands-based N,O-chelated binuclear boron-fluoride [L_n(BF₂)₂] (n = L₁–L₆ or L_1a–L_2a) complexes have been prepared and characterized by a variety of spectroscopic techniques (¹H, ¹³C and ¹⁹F NMR, FT-IR, UV-Vis, LC-MS, and fluorescence spectra) and elemental analysis. All of the binuclear boron-fluoride complexes exhibit strong absorption bands due to S₀→S₁ transitions and strong fluorescence properties were observed at room temperature in the solution. The binuclear boron complexes containing two naphthyl groups are significantly red-shifted in comparison with the other binuclear boron-fluoride complexes. After the structures are characterized, these hemi-salen and salan ligand-based N, O-chelated binuclear boron-fluoride complexes were utilized to the transfer hydrogenation of the different acetophenone derivatives conversion to 1-phenylethanol derivatives as catalysts.     

Age hardening of EN AW 2014 alloy extruded in the semi-solid state

Response to T6 heat treatment of thixoextruded EN AW 2014 aluminium alloy was investigated in the present work. Extrusion of a 2014 slug heated to a liquid fraction of 15%, takes place in the semi-solid state until the liquid fraction in the final part of the slug is reduced via segregation to a level where semi-solid forming is no longer possible. Hence, the final part of the slug is extruded in the solid-state with a concurrent recrystallization process. This process has produced two distinctly different structures at the front and rear ends and an unexpected hardness profile in T6 temper along the length of the thixoextruded rod. The response to T6 heat treatment of the globular front has been age hardening as usual. The inferior age hardening potential with respect to the hot extruded counterpart is attributed to the grain boundary Al₂Cu phase which has grown too coarse via liquid segregation to be readily solutionized at typical solutionizing temperatures. The rear end of the extrudate on the other hand, has softened upon T6 heat treatment owing to Cu depletion and a fully recrystallized structure.     

Metabolic profile and biological activity of Sideritis brevibracteata P. H. Davis endemic to Turkey

Essential oil and phenolic compositions of Sideritis brevibracteata P.H. Davis, which is an endemic species in Turkey and commonly used as a herbal tea for some diseases, were determined by GC-MS and Liquid chromatography–mass spectrometry (LC-MS/MS) techniques. While the main components of the essential oil were determined as caryophyllene, germacrene-D, and α-cadinene, the phenolic compounds quercetagetin-3,6-dimethylether and chlorogenic acid were found to be the main compounds in the extracts of the species. The characteristic diterpenoids of Sideritis species such as siderol, linearol, eubotriol, sideridiol, and athonolone were isolated and their structures were elucidated by 1D and 2D NMR (Nuclear Magnetic Resonance) techniques. Weak inhibitory activity of species against butyryl-cholinesterase was determined. Antioxidant capacity of the acetone and methanol extracts was determined by DPPH free radical scavenging activity, β-carotene linoleic acid assays, and CUPRAC assays.     

Preparation and Characterization of KNbO3 Ceramics

The processing and characterization of electrical properties of potassium niobate ceramic, KNbO₃ (KN) have been studied. The difficulty of obtaining dense samples by conventional methods limits the knowledge on electrical properties of this material. In this paper, a complete route for processing of KN with density over 94% is described. Piezoelectric and dielectric data are presented. It is observed that the major problem concerning the density is related to incorrect stoichiometry, which is believed to be a more critical issue for this system compared with other electro-ceramics.