One-bit quantization has received attention due to its simplicity, low cost, and ability to recover the autocorrelation of the unquantized data. In the past, the autocorrelation estimation from one-bit data can be done in two separate stages. One is the power estimation by using one-bit quantizers of non-zero thresholds, while the other focuses on estimating the normalized autocorrelation with one-bit quantizers of a zero threshold. However, the overall hardware cost increases in this approach. This paper presents an autocorrelation estimator based on a one-bit quantizer with a non-zero threshold. The proposed method depends purely on a one-bit quantizer and its output data. Our method first infers the power information and then estimates the normalized autocorrelation by polynomial root-finding. The autocorrelation estimate is obtained by combining the power and the normalized autocorrelation. Numerical simulations show that the proposed method exhibits similar behavior to an estimator based on the unquantized data, with a 5dB loss in the estimation error.
A series of photosensitive hydrophilic agents (T20) comprising Tween-20, isophorone diisocyanate, and 2-hydroxyethyl methacrylate moieties were synthesized and used in the preparation of antifog/frost resistant (AFF) hard coatings on plastic substrates. By means of a hydrophilic/hydrophobic bilayer design, the prepared coatings demonstrated not only AFF property but also water resistibility. The bottom layer is an organic-inorganic composite consisting of SiO 2 nanoparticles embedded in a polymeric network of crosslinked dipentaethritol hexaacrylate. The AFF layer incorporates T20 in the formulations and links covalently with the bottom layer through a UV-curing polymerization process. Various methods, for example, FTIR, SEM, contact angle, and steam/defrosting tests, were employed to characterize the prepared coatings. Optimally, the coatings were found to be transparent, strong (4H, pencil hardness), adhering perfectly (level 5B) to the poly(methyl methacrylate) substrate, and could be soaked in water for 24 h at 25 C without losing hydrophilicity (contact angle~0 ) or antifogging capability.Recently, a new promising approach was reported which introduced the layer-by-layer (LBL) assembly technique to prepare coatings that demonstrated both antifogging and antifrosting effects. [35][36][37][38][39] For example, Lee et al. assembled PVA/PAA multilayers and then post-treated with poly(ethylene glycol) methyl ether (PEG) to produce AFF coatings. 37 The PEG segments were found to serve, in addition to PVA and PAA, as sites to absorb nonfreezing water and prevent formation Additional Supporting Information may be found in the online version of this article.
Dye-grafted silica nanoparticles (GSiO 2 ) were synthesized via a dual-step process involving, first, attachment of the organic dye Disperse Red 1 (DR1) to the coupling agent, 3-isocyanatopropyltriethoxysilane, by means of urethane bonds, and then grafting of the silylated-DR1 onto silica nanoparticles ($6 nm) prepared by hydrolysis and condensation of tetraethoxysilane in a sol-gel process. Dye-adsorbed silica nanoparticles (DSiO 2 ) were also prepared for comparison, for which DR1 was bound only physically to silica instead of covalent bonds. The thermal behaviors of the formed GSiO 2 and DSiO 2 were examined by means of differential scanning calorimetry and thermal gravimetric analysis. The results showed that both the particle size and silica content have significant effects on the thermal behaviors of the dye-adsorbed and dye-grafted silica. Moreover, crystalline DR1 lost significantly its crystallinity after being adsorbed on silica, and became virtually amorphous after being grafted onto silica. The formed particles were UV-cured with a multifunctional acrylic monomer to yield color coatings on glass substrates. UVvisible spectra indicated that brightness and color saturation of the coating comprising GSiO 2 could be maintained better than that comprising DSiO 2 after heat treatment at 280°C.
The correlation equations for predicting local permeate fluxes in tubular-membrane ultrafilters were derived from mass and momentum balances by the modified resistance-in-series model with the considerations of the increment of concentration polarization and the declines of transmembrane pressure and flow rate, along the membrane tube. Ultrafiltration of dextran T500 aqueous solution in a tubular microporous ceramic module has been carried out under various feed concentrations, transmembrane pressures, and feed flow rates, and many experimental data of ten-point local permeate fluxes along the tube were obtained to confirm the correlation predictions. The increment of concentration polarization, as well as the decline of permeate flux, along the tube was also discussed.
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