Sharif Digital Repository

Among the many attacks against watermarked data, the gain attack is less supported with countermeasures. The effectiveness of this attack becomes more evident in quantization-based embedding algorithms such as Dither Modulation (DM). In this paper, the general solution for both block and sample type DM schemes that are robust against gain attacks is considered. Among the solutions, we concentrate on a subclass of the algorithms which are insensitive to additive noise attacks; i.e., we introduce watermarking schemes which are both robust against gain and additive noise attacks. The simulation results confirm the desired performance of the final algorithm against these attacks while outperform... 

In addition to some approaches such as changing the working fluid or number of turns in a pulsating heat pipe (PHP), geometrical changes are also appealing for enhancing the thermal performance of this type of heat pipes. The main idea of this investigation is to increase heat transfer rate by increasing flow circulation of working fluid. By placing an additional branch in the evaporator section, a secondary bubble pump was created which improved the circulation of fluid inside PHP. In order to investigate the impact of this additional branch, two similar one-turn copper heat pipes were fabricated. One of them was the conventional PHP and the other had an additional branch and is named... 

In this study, homo- and co-polypropylene were modified by nanometric calcium carbonate and the effect of additive on scratch resistance was evaluated. Results of this study show that the length of scratch curvature can be considered as an acceptable criterion to evaluate the scratch resistance of polymers. Also, it was found that addition of calcium carbonate to homo-polypropylene increases scratch resistance of this polymer, but its effect on co-polypropylene is insignificant. Based on the results of this work, one may claim that incorporation of nanometric particles with good adhesion to the matrix and well dispersion might be effective in enhancement of scratch resistance. Formation of... 

Mazut as a source content of various hydrocarbons is hard to be degraded and its cracking could turn mazut into useful materials. Nevertheless degradation of mazut by routine methods is too expensive but application of indigenous microorganisms as biocatalysts could be effective and important to lower the costs and expand its consumption. Mazut biodegradation can be improved using various strategies; Therefore in this study newly isolated strain Enterobacter cloacae BBRC 10061 was used in a method of gradual addition of mazut into medium and its results were compared with simple addition method. To investigate degradation of mazut by BBRC 10061, influence of increase of mazut concentration... 

Michael addition reaction of anthrone to nitroolefins is described in water without using any catalyst to prepare 9-(2-nitro-1-arylethyl)anthracene-10(9H)- ones. This method is green and efficient and gives good yields of products. The solvent effect is also investigated  

The green synthesis of a new series of polycyclic procyanidin derivatives has been achieved in good yields by tandem dinucleophilic addition of indolin-2-thiones to flavylium salts. The procedure is efficient and simple, and the substrates are easily available  

Four metal dithiocarbamate complexes (Zn, Ni, Hg and Sn) based on an amine containing pyridyl and nitrile groups, 3-((pyridin-2-yl)methylamino)propanenitrile, were prepared and characterized by their elemental analysis, spectroscopic data (such as IR, 1H and 13C NMR), TGA analysis and X-ray crystallography of the Ni(II) complex. The presence of a band in the 1000 cm-1 region in the IR spectra, without any splitting, confirms the symmetrical bidentate bonding mode of the dithiocarbamate ligand. Also, the short thioureide C=N distance in the X-ray analysis of the Ni complex confirms the delocalization of π electrons over the S2CN moiety and strong double bond character between the carbon and... 

The present investigation introduces a new series of cycloplatinated(II) complexes, with the general formula Pt(O-bpy)(Me)(CN-R)] (R = benzyl, 2-naphtyl and tert-butyl), which are able to generate the stable trans-Pt(IV) product in the solution after the reaction with iodomethane. In fact, the trans product is both the kinetic and thermodynamic product of the reaction; this observation was supported by DFT calculations. These Pt(II) complexes are supported by 2,2'-bipyridine N-oxide (O-bpy) and one of several isocyanides as the cyclometalated and ancillary ligands, respectively. These new Pt(II) complexes undergo oxidative addition with MeI to give the corresponding trans-Pt(IV) complexes.... 

Abstract: The waste stream of electrical and electronic equipment is three times faster than other municipal waste streams. Recycling of electronic waste is necessary for both reducing environmental pollution and saving natural ores. Bioleaching is known as an efficient technology for metal leaching. In most of the previous studies on the bioleaching of electronic waste, the pH of the process was adjusted daily under the optimal pH of the bacterium growth. Using acid causes increasing process costs and unsustainability of the process. In this work, the effect of daily pH adjustment on the bioleaching efficiency of electronic waste using adapted Acidithiobacillus ferrooxidans was studied.... 

A mild, convenient, and practical one-pot procedure for the direct synthesis of dithiocarbamates has been developed by condensation of amines, CS2, and a Michael acceptor, under solvent-free conditions at room temperature in good to excellent yields. © Georg Thieme Verlag Stuttgart  

In copper electrorefining process, some additives are added to the electrolyte to improve the morphology of cathode deposits as well as the quality of products. In the present investigation, the effects of thiourea, glue and chloride ions (as additives) on the passivation of industrial copper anodes under high current densities have been reported. Experiments were conducted at 65 °C; using a synthetic electrolyte containing 40 g/l Cu2+ and 160 g/l H2SO4. Results obtained from chronopotentiometry experiments showed that increasing the concentration of chloride ion leads to increase in passivation time. The results also indicated that from a certain level on, namely 2 ppm, the increase in... 

Herein we report a new organocatalyst for the asymmetric Michael addition of nitroalkanes to α,β-unsaturated aldehydes. This catalyst incorporates a basic imidazole group in addition to the secondary amine responsible for activation of the α,β-unsaturated carbonyl compounds via iminium ion formation. The new organocatalyst is capable of catalyzing the enantioselective carbon-carbon bond formation with a high degree of enantiocontrol providing products in enantiomeric excesses of up to 92% and yields of up to to 91 %. These results constitute the best results so far reported for organocatalyzed Michael additions of nitroalkanes to α,β-unsaturated aldehydes, and provide proof of principle that... 

The mechanism of electrochemical behavior of catechol in the presence of thiaproline is investigated by cyclic voltammetry, controlled-potential coulometry and spectrophotometric tracing of the reaction coordinate. The results indicate that thiaproline participate in with an ECEC mechanism in a nucleophilic (Michael) addition to o-quinone. Effect of pH of buffer solution on reaction pathway is studied and showed that addition of thiaproline to the o-quinone is performed only in solutions with pHs higher than 5. These results indicate that the addition of thiaproline is occurred first from amine functional group. In the second step, the addition of carboxylate group of thiaproline to C-5 of... 

KF/Al2O3 efficiently catalyzes aza-Michael addition of indole and 3-methylindole to a variety of electron-deficient conjugated alkenes such as α,β-unsaturated ketones, amides and nitriles. The N-alkylation adducts are produced in good to excellent yields and relatively in short times. The catalyst can be recycled for subsequent reactions without any appreciable loss of efficiency. © 2006 Bentham Science Publishers Ltd  

A new fast and very accurate method for target detection in PCL radars is presented. This algorithm in noisy environment with SNR up to -60dB could provide the perfect and accurate detection. Presented initiative algorithm apply a special filter bank to the target signal and clean the additive noise of the environment from it and detect the multiple targets with different RCSs. © 2006 EuMA  

An Artificial Neural Network (ANN) based helicopter identification system is proposed. All helicopters emit certain characteristic acoustic signatures, which are specific to them. This is due to some differences in their structures and design. These differences in acoustic signatures can be used with neural networks for detection and classification of different types of helicopters. The conventional system uses the ratio of the main-rotor blade passage frequency (bpf) to the tail-rotor bpf. The ANN is trained to use similar main/tail-rotor information, in addition to the parametric spectral representation technique (Reflection Coefficients). It is also shown that the classifier performance...