An integrated technico-economical methodology for solving reactivepower compensation problem

This paper provides a trade-off methodology for the solving reactive power compensation (RPC) problem. It is based on the full integration of two technical and economical aspects of the problem, that were previously considered either separately or combined as an objective function and its constraints. Minimization of the cost-economic function is based on the use of Y-matrix method. Voltage profile improvement is accomplished through a simplex algorithm based on the use of a sensitivity matrix (S). This paper proposes a modified computation of S in order to fit within the overall integration. The affinity of both technical and economical approaches, promotes this integration: both are based on linear programming techniques, coupled to the same load flow, and use similar Y and Z matrix components. The symmetry and sparsity characteristics of the Y matrix allow the reduction of the required mathematical calculations. This trade-off technique is tested on the IEEE 39-bus system. The modified simplex approach resulted in lower reactive power allocation while maintaining competitive voltage profile. Tests also showed that neither the technical nor the economical solution is complete by itself. A large scope of possible RPC allocations, is therefore provided to the decision maker to define his priorities and seek an `optimal decision'     

Modified wheat gluten as a binder in particleboard made from reed

To evaluate the utilization of reed in environmental friendly high‐density particleboard, modified wheat gluten was used with urea‐formaldehyde as a binder in different ratios, applying the optimum conditions obtained on using UF resin alone. The scanning electron microscopy of the reed fibers showed that the fibers are cylindrical in shape, which helps in enhancing the adhesion between the binder and the inner and outer surfaces of the fibers. The dependence of the mechanical properties (modulus of rupture, modulus of elasticity and the internal bond) and the physical properties (water absorption and thickness swelling) on the urea‐formaldehyde/modified gluten ratios was studied. Addition of 1% and 2% boric acid as a fungicide to the binder mixture resulted in no significant change in the mechanical properties and slight improvement in the physical properties of the produced particleboard. Thermogravimetric analyses of selected samples were done to study the thermal stability of the particleboard bonded with the modified binder with and without boric acid. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Reinforcement of natural rubber with nylon 6 short fibers

The properties of natural rubber vulcanizates reinforced with nylon 6 short fibers were studied. It was found that the stress of vulcanizates decreased with initial fiber loading, followed by an increase with increasing the amount of fiber. The effect of reinforcing carbon black HAF on the physicomechanical properties was studied in the presence and absence of hydrated silica.     

Ultrasensitive identification of localization variants of modified peptides using ion mobility spectrometry

Localization of the modification sites on peptides is challenging, particularly when multiple modifications or mixtures of localization isomers (variants) are involved. Such variants commonly coelute in liquid chromatography and may be undistinguishable in tandem mass spectrometry (MS/MS) for lack of unique fragments. Here, we have resolved the variants of singly and doubly phosphorylated peptides employing drift tube ion mobility spectrometry (IMS) coupled to time-of-flight mass spectrometry. Even with a moderate IMS resolving power of ～80-100, substantial separation was achieved for both 2+ and 3+ ions normally generated by electrospray ionization, including for the variants indistinguishable by MS/MS. Variants often exhibit a distribution of 3-D conformers, which can be adjusted for optimum IMS separation by prior field heating of ions in a funnel trap. The peak assignments were confirmed using MS/MS after IMS separation, but known species could be identified using just the ion mobility "tag". Avoiding the MS/MS step lowers the detection limit of localization variants to <100 amol, an order of magnitude better than that provided by electron transfer dissociation in an Orbitrap MS.     

Pulsed multiple reaction monitoring approach to enhancing sensitivity of a tandem quadrupole mass spectrometer

Liquid chromatography (LC)-triple quadrupole mass spectrometers operating in a multiple reaction monitoring (MRM) mode are increasingly used for quantitative analysis of low-abundance analytes in highly complex biochemical matrixes. After development and selection of optimum MRM transitions, sensitivity and data quality limitations are largely related to mass spectral peak interferences from sample or matrix constituents and statistical limitations at low number of ions reaching the detector. Herein, we report on a new approach to enhancing MRM sensitivity by converting the continuous stream of ions from the ion source into a pulsed ion beam through the use of an ion funnel trap (IFT). Evaluation of the pulsed MRM approach was performed with a tryptic digest of Shewanella oneidensis strain MR-1 spiked with several model peptides. The sensitivity improvement observed with the IFT coupled in to the triple quadrupole instrument is based on several unique features. First, ion accumulation radio frequency (rf) ion trap facilitates improved droplet desolvation, which is manifested in the reduced background ion noise at the detector. Second, signal amplitude for a given transition is enhanced because of an order-of-magnitude increase in the ion charge density compared to a continuous mode of operation. Third, signal detection at the full duty cycle is obtained, as the trap use eliminates dead times between transitions, which are inevitable with continuous ion streams. In comparison with the conventional approach, the pulsed MRM signals showed 5-fold enhanced peak amplitude and 2-3-fold reduced chemical background, resulting in an improvement in the limit of detection (LOD) by a factor of ～4-8.     

Recycling of shredded currency waste of Egyptian Central Bank for making good-quality papers

The present study aimed at studying the recycling of shredded currency waste of The Egyptian Central Bank, ECB, in the form of good-quality products. The techniques used include soaking with chemicals, screening to separate the detached ink particles from the soaking step, pulping at high temperature, screening to separate large nylon pieces and small ink particles, flotation to separate large ink particles and small pieces of nylon and bleaching as the final step to increase the whiteness of the product.     

Variation tolerant design methods for wideband low noise amplifiers

In this paper, we develop design techniques for reducing the impact of manufacturing variations on wideband low noise amplifiers (LNA). Utilizing an efficient modeling and circuit optimization method, we investigate the sensitivity of LNA performance metrics to process variations and determine that the input impedance matching is particularly sensitive to perturbations in component values. To mitigate the impact of process variations on the input impedance matching, we add additional circuit elements and tunable capacitors to dynamically compensate for manufacturing variations after fabrication. The results indicate that the proposed design techniques can increase manufacturing yield by up to one order of magnitude for input impedance matching with only a 14% increase in noise figure.     

Dielectric Properties of Styrene—Butadiene Rubber/Silicon Dioxide Mixtures

The dielectric constant ?′ and dielectric loss ?″ have been investigated for SBR samples vulcanized with TMTD and loaded with silica in increasing quantities in the frequency range from 60 Hz to 10⁸ Hz at room temperature. Also, the physico-mechanical properties of these samples have been investigated. The results of ?′ and ?″ are analysed using the Cole—Cole method. Two absorption regions are found: a low frequency absorption region with a maximum at about 10 kHz which is attributed to Maxwell—Wagner effect and a high frequency absorption region with a maximum at 10⁷ Hz which is due to the orientation of polar groups. A third absorption region appeared at frequencies below 100 Hz and may be due to absorption of moisture arising from the presence of silica in the sample.