Radial hydraulic machinery four-quadrant performance curves dependent on specific speed and applied in transient calculations

The paper presents research analysis of possible analytical relationships that could exist in pointwise data for four-quadrant performance curves of one radial pump and seven pump-turbines for which the authors collected the basic data and performed the calculation. All the performance curves are for different specific speeds. Additionally, the examples of transformation calculation from the four-quadrant curves into Suter form curves shown in [1] - Thorley (1996) and [2] - Stepanoff (1959) have been presented. A numerical model has been developed for the calculation of transient processes in hydropower plants with installed pumps and pump-turbines. As an input data, the analytical relationships found in the previous research analysis have been used, as well as the pointwise curves for various specific speeds. The multi comparison of the results has been made and comprehensive conclusions given

Radial hydraulic machinery four-quadrant performance curves dependent on specific speed and applied in transient calculations

The paper presents research analysis of possible analytical relationships that could exist in pointwise data for four-quadrant performance curves of one radial pump and seven pump-turbines for which the authors collected the basic data and performed the calculation. All the performance curves are for different specific speeds. Additionally, the examples of transformation calculation from the four-quadrant curves into Suter form curves shown in [1] - Thorley (1996) and [2] - Stepanoff (1959) have been presented. A numerical model has been developed for the calculation of transient processes in hydropower plants with installed pumps and pump-turbines. As an input data, the analytical relationships found in the previous research analysis have been used, as well as the pointwise curves for various specific speeds. The multi comparison of the results has been made and comprehensive conclusions given

Demonstration of silicon-on-insulator mid-infrared spectrometers operating at 3.8µm

The design and characterization of silicon-on-insulator mid- infrared spectrometers operating at 3.8µm is reported. The devices are fabricated on 200mm SOI wafers in a CMOS pilot line. Both arrayed waveguide grating structures and planar concave grating structures were designed and tested. Low insertion loss (1.5-2.5dB) and good crosstalk characteristics (15-20dB) are demonstrated, together with waveguide propagation losses in the range of 3 to 6dB/cm

The effects of detergent, sodium tripoly-phosphate and ethoxyled oleyl-cetyl alcohol on metabolic parameters of the fungus trichothecium roseum link

The degradation of detergents that are dispersed in water and soil partially depends on the metabolic activities of fungi. Among the fungi that have this ability, Deuteromycetes are particularly noted for their biochemical characteristics. Taking this into account, it was of interest to analyze the influence of detergent and its main compounds, ethoxyled oleylcetyl alcohol (AOC) and sodium tripoly-phosphate (TTP), on the metabolism of the fungus Trichothecium roseum. Our results revealed that both detergent and AOC had an inhibitory effect on the bioproduction of free organic acids, while TTP stimulated their production. Also, detergent inhibited the bioproduction of basic amino acids, with the exception of alanine. In addition, detergent applied at 1% concentration inhibited the bioproduction of proteins and the total biomass of the fungus, while AOC and TTP inhibited the production of proteins, but stimulatedl the production of Trichothecium

Recent breakthroughs in carrier depletion based silicon optical modulators

The majority of the most successful optical modulators in silicon demonstrated in recent years operate via the plasma dispersion effect and are more specifically based upon free carrier depletion in a silicon rib waveguide. In this work we overview the different types of free carrier depletion type optical modulators in silicon. A summary of some recent example devices for each configuration is then presented together with the performance that they have achieved. Finally an insight into some current research trends involving silicon based optical modulators is provided including integration, operation in the mid-infrared wavelength range and application in short and long haul data transmission link

Suspended silicon mid-infrared waveguide devices with subwavelength grating metamaterial cladding

We present several fundamental photonic building blocks based on suspended silicon waveguides supported by a lateral cladding comprising subwavelength grating metamaterial. We discuss the design, fabrication, and characterization of waveguide bends, multimode interference devices and Mach-Zehnder interferometers for the 3715 - 3800 nm wavelength range, demonstrated for the first time in this platform. The waveguide propagation loss of 0.82 dB/cm is reported, some of the lowest loss yet achieved in silicon waveguides for this wavelength range. These results establish a direct path to ultimately extending the operational wavelength range of silicon wire waveguides to the entire transparency window of silicon

Polimerni magnetni kompoziti na bazi Nd-Fe-B

Various types and contents of magnetic powder and polymer matrix induce different mechanical, magnetic, electrical and optical properties of final composite material. The strong influence of relatively small amounts of filler particles on the dynamic mechanical properties of polymers has significantly contributed to increased use of polymer materials in many commercial applications. The higher content of magnetic filler has direct influence on magnetic properties of composites, but also may change the rheology of polymer melt during process and, subsequently, impact the mechanical strength of bonded magnets. For better insight into viscoelastic behaviour of composites, beside experiments, a theory that explicitly takes the shape factor, particle distribution, particle-particle interactions as well as particle-polymer matrix interactions into account is required. The mathematical prediction of storage modulus behaviour is examined. The several proposed analytical models are tested versus experimental results. Some of applied models agree very well with experimental data, whilst others deviate significantly.Različite vrste primenjenih magnetnih prahova i polimerne matrice, kao i njihovi udeli, utiču na mehanička, magnetna, električna i optička svojstva finalnog kompozitnog materijala. Veliki uticaj relativno malih udela čestica punioca na dinamičko mehanička svojstva polimera značajno doprinosi većoj komercijalnoj upotrebi kompozitnih materijala. Veliki udeli magnetnog praha u mnogome utiču na magnetna svojstva kompozita, ali takođe mogu dovesti do reoloških promena u polimeru tokom procesa topljenja, što ima direktan uticaj na mehanička svojstva polimerom vezanih (bonded) magneta. Radi boljeg uvida u visokoelastična svojstva kompozita, osim eksperimenata, neophodno je uzeti u obzir i teorijska razmatranja koja eksplicitno objašnjavaju uticaj faktora oblika, raspodelu čestica, interakcije između čestica, kao i interakcije između čestica i polimera. U tom smislu vršeno je i matematičko predviđanje ponašanja modula uskladištene energije (E') kompozita. Nekoliko predloženih analitičkih modela su testirani i upoređeni sa eksperimentalnim rezultatima. Neki od primenjenih modela se veoma dobro slažu sa dobijenim eksperimentalnim rezultatima, dok neki značajno odstupaju

Dynamic Mechanical Behaviour of Polymer Bonded Nd-Fe-B Composite Materials

Magnetic composite materials with varied content of Nd-Fe-B particles in epoxy matrix are examined from a dynamic mechanical perspective. Structural, viscoelastic and magnetic properties of composites have been observed using Scanning Electron Microscope (SEM), Dynamic Mechanical Analysis (DMA) and Super Quantum Interference Device (SQUID) magnetometer, respectively. Experimental results show that magnetic properties and corresponding dynamic mechanical behaviour depend on packing density. Also, results observed by predictive mathematical models suggest that maximal packing factor has a direct impact on elastic behaviour of composites. [doi:10.2320/matertrans.M2011218

A Mumps Outbreak in Vojvodina, Serbia, in 2012 Underlines the Need for Additional Vaccination Opportunities for Young Adults

In 2012, mumps was introduced from Bosnia and Herzegovina to Vojvodina, causing an outbreak with 335 reported cases. The present manuscript analyses the epidemiological and laboratory characteristics of this outbreak, identifies its main causes and suggests potential future preventive measures. Sera of 133 patients were tested for mumps-specific antibodies by ELISA and 15 nose/throat swabs were investigated for mumps virus RNA by RT-PCR. IgG antibodies were found in 127 patients (95.5%). Mumps infection was laboratory-confirmed in 53 patients, including 44 IgM and 9 PCR positive cases. All other 282 cases were classified as epidemiologically-confirmed. More than half of the patients (n = 181, 54%) were 20-29 years old, followed by the 15-19 age bracket (n = 95, 28.4%). Twice as many males as females were affected (67% versus 33%). Disease complications were reported in 13 cases (3.9%), including 9 patients with orchitis and 4 with pancreatitis. According to medical records or anamnestic data, 190 patients (56.7%) were immunized with two doses and 35 (10.4%) with one dose of mumps-containing vaccine. The Serbian sequences corresponded to a minor genotype G variant detected during the 2011/2012 mumps outbreak in Bosnia and Herzegovina. Vaccine failures, the initial one-dose immunization policy and a vaccine shortage between 1999 and 2002 contributed to the outbreak. Additional vaccination opportunities should be offered to young adults during transition periods in their life trajectories