1,720,981 research outputs found
ELECTROMAGNETIC-INTERFERENCE FROM DIGITAL SIGNAL TRANSMISSION ON POWER-LINE CARRIER CHANNELS
No full text
OXIDATION RATES OF A SINGLE CHAR PARTICLE IN AN ELECTRODYNAMIC BALANCE
No full textThe changes in reaction rate of a carbon char with conversion in the temperature range 500-1200 K are followed by using an electrodynamic balance (EDB). This device allows, in a temperature range wider than in other apparatus, in situ measurements of mass, diameter, density, surface area, rate of reaction, and temperature for a single, suspended submillimeter particle as the reaction takes place. A synthetic char (Spherocarb) has been used because of its low ash and volatile matter contents and its spherical shape. The results on oxidation kinetics obtained in an EDB are compared with low-temperature reaction rate data, obtained by conventional thermogravimetric apparatus on Spherocarb, and with the data obtained in an entrained-flow reactor at temperatures typical of pulverized-fuels combustors. The correlation between all the data in the temperature range 500-2300 K is examined. EDB data can be combined with entrained-flow data to depict a sharp change in reaction regime from a chemical kinetic to an internal diffusion control. A simple Thiele analysis, considering different classes of pores, yields results that suggest pores in the 100-1000 nm range are responsible for diffusional constraints that cause the kinetic data to depart from the chemical regime
MORPHOLOGICAL-CHANGES DURING OXIDATION OF A SINGLE CHAR PARTICLE
No full textThe e v o l u t i o n of pore s i z e d i s t r i b u t i o n d u r i n g t h e o x i d a t i o n of
s i n g l e Spherocarb c h a r p a r t i c l e s has been measured u n d e r c h e m i c a l
c o n t r o l l e d c o n d i t i o n s . E l e c t r o d y n a m i c a l l y l e v i t a t e d p a r t i c l e s were
heated t o r e a c t i o n t e m p e r a t u r e u s i n g a l a s e r and t h e weight and s i z e
changes m o n i t o r e d . The l a s e r h e a t i n g was i n t e r r u y p t e d a t s e l e c t e d
c o n v e r s i o n s and t h e C 0 2 a d s o r p t i o n determined at ambient c o n d i t i o n s .
A s r e a c t i o n p r o c e e d s , p a r t i c l e s a r e found t o s h r i n k , t h e macropore
volume d e c r e a s e s i n p r o p o r t i o n t o t h e t o t a l p a r t i c l e volume,
m a i n t a i n i n g a c o n s t a n t m a c r o p o r o s i t y . The micropore volume, however,
d e c r e a s e s w i t h i n c r e a s i n g c o n v e r s i o n whereas t h e n o r m a l i z e d p o r e
size d i s t r i b u t i o n remains unchanged, s u g g e s t i n g t h a t t h e
d e n s i f i c a t i o n of t h e microporous volume which l e a d s to. p a r t i c l e
s h r i n k a g e r e s u l t s from pore e l i m i n a t i o n . A t t h e same time t h e
mesopore volume i n c r e a s e s with i n c r e a s i n g c o n v e r s i o n i n d i c a t i n g t h a t
t h e mesopores play a dominant r o l e i n t h e c h a r r e a c t i o
Closed-form analytical design of optically transparent wideband absorbers for 5G technology
No full textThe design of new transparent absorbers for the upcoming fifth-generation (5G) technology is investigated. The absorbers consist of a matching layer, a lossy sheet, a spacer, and a back conducting layer (BCL). Both the matching layer and the spacer are one-quarter-wavelength thick and made of polyethylene terephthalate (PET). The lossy sheet and the BCL consist of indium tin oxide (ITO) thin films or graphene-PET laminates in order to avoid the use of any metal and to guarantee the optical transmittance. An innovative closed-form formulation is developed with the aim of evaluating the optimal values of sheet resistances of the lossy layers through analytical expressions. The absorption performances are investigated considering impinging plane waves with an incidence angle between 0° and 30°. The computed absorption coefficients in transverse magnetic (TM) or transverse electric (TE) modes are greater than 0.8, and the transmission coefficient is lower than 0.1 in the 5G frequency range from 25 up to 47 GHz, assuming that the matching layer and the spacer are 1.3 mm thick. The optical transmittance of the absorbers is evaluated in the wavelength range from 400 up to 700 nm by means of an accurate matrix simulation model, considering both optical polarizations, S (i.e., TE) and P (i.e., TM) for different incidence angles. The computed average optical transmittances of the designed absorbers are greater than 80% at 550 nm, i.e., at the wavelength corresponding to the maximum eye sensitivit
Combined FDTD/TL analysis of electromagnetic interference effects on complex aerospace systems
No full textAnti-Ro and anti-La autoantibodies induce TNF- production by human salivary gland cells: an in vitro study
No full textIn this report, we demonstrate that both TNFR1 and the TNFR2 are expressed on the salivary gland cell line A-253 cell membrane. Furthermore, cell treatment with anti-Ro and anti-La autoantibodies from Sjögren IgG determined TNF-alpha production, clarifying which could be the inducer of the extrinsic pathway of apoptosis in salivary gland cells
- …
