Design and analysis of efficient QCA reversible adders

The Journal of Supercomputing - Quantum-dot cellular automata (QCA) as an emerging nanotechnology are envisioned to overcome the scaling and the heat dissipation issues of the current CMOS...     

The effect of nanoparticles on oil sludge biodegradation by Chromohalobacter sp. isolated from the Bahregan area in the Persian Gulf

In this study, sampling was performed from oil-sludge-contaminated site from Bahregan area in the Persian Gulf of Iran. Alkane-degrading bacteria from oil sludge were isolated by chemotaxis in hydroxylase gene. Thus, Chromohalobacter strain was selected as useful strain for the biodegradation of oil sludge. The biodegradation of oil sludge by Chromohalobacter in the absence and presence of nanoparticles in light and dark conditions was investigated by gas chromatography–mass spectrometry analysis. Results of analysis showed that although Chromohalobacter is capable of the biodegradation of oil sludge, Fe₂O₃ and Fe₃O₄ nanoparticles with this bacterium increase the biodegradation in a short time.     

Vibration of double-walled carbon nanotubes coupled by temperature-dependent medium under a moving nanoparticle with multi physical fields

A numerical model on nonlinear vibration of double-walled carbon nanotubes (DWCNTs) subjected to a moving nanoparticle and multi physical fields is proposed. DWCNTs are considered with the kinematic assumption of Euler–Bernoulli beam theory. The surrounding elastic substrate is simulated as Pasternak foundation, which is assumed to be temperature-dependent. Hamilton's principle, incremental harmonic balanced method, Galerkin, and time integration method with direct iteration are employed to establish the equations of motion of zigzag DWCNTs. The study reveals that for the weak van der Waals forces, DWCNTs have the positive and the negative deflections as if it vibrates under a moving nanoparticle.     

On the interference management in wireless multi-user networks

A study on interference management schemes in wireless multi-user networks is presented. We analyze the interference management problem in cellular networks and show that interference management is an optimization problem, for which we propose a general formulation. Using this general formulations we show that different interference management approaches are either exact or approximated solutions to this optimization problem. For each radio resource management technique, we provide a general overview and discuss its relation vis-a-vie other interference management techniques. As a case study, we then apply the proposed general formulation on the interference management in OFDM wireless networks and show that it results in a joint transmit scheduling and dynamic sub-carrier and power allocation scheme. A polynomial-time heuristic algorithm is also proposed to solve the formulated optimization problem. The distinguishing feature of the proposed scheme is that it gives in one shot, the transmission scheduling, the sub-carriers assigned to each user, and the power allocated to each sub-carrier, based on a fair and efficient framework while satisfying the delay requirements of real-time users.     

Novel design of a fast reversible Wallace sign multiplier circuit in nanotechnology

Today, reversible logic is emerging as an intensely studied research topic, having applications in diverse fields, such as low-power design, optical information processing, and quantum computation. In this paper, we have proposed two reversible Wallace signed multiplier circuits through modified Baugh-Wooley approach, which are much better than the two available counterparts in all the terms. The multiplier is an essential building block for the construction of computational units of quantum computers. Besides, we need signed multiplier circuits for numerous operations. However, only two reversible signed multiplier circuits have been presented so far. In the first proposed architecture, our goals are to decrease the depth of the circuit and to increase the speed of the circuit. In the second proposed circuit, we aimed to improve the quantum cost, garbage outputs, and other parameters. All the proposed circuits are in the nanometric scales and can be used in the design of very complex systems.     

Response of reinforced concrete structures to macrocell corrosion of reinforcements. Part I: Before propagation of microcracks via an analytical approach

Assessment of the macrocell corrosion which deteriorates reinforced concrete (RC) structures have attracted the attention of many researchers during recent years. In this type of rebar corrosion, the reduction in cross-section of the rebar is significantly accelerated due to the large ratio of the cathode's area to the anode's area. In order to examine the problem, an analytical solution is proposed for prediction of the response of the RC structure from the time of steel depassivation to the stage just prior to the onset of microcrack propagation. To this end, a circular cylindrical RC member under axisymmetric macrocell corrosion of the reinforcement is considered. Both cases of the symmetric and asymmetric rebar corrosion along the length of the anode zone are studied. According to the experimentally observed data, corrosion products are modeled as a thin layer with a nonlinear stress–strain relation. The exact expressions of the elastic fields associated with the steel, and concrete media are obtained using Love's potential function. By imposing the boundary conditions, the resulting set of nonlinear equations are solved in each time step by Newton's method. The effects of the key parameters which have dominating role in the time of the onset of concrete cracking and maximum radial stress field of the concrete have been examined.     

Response of reinforced concrete structures to macrocell corrosion of reinforcements. Part II: After propagation of microcracks via a numerical approach

Investigation of response of reinforced concrete (RC) structures due to axisymmetric macrocell corrosion of rebars is of concern after propagation of microcracks within the concrete medium. The geometry, boundary and interfaces conditions of the present problem are identical to those stated in part I. As seen in the companion paper, the exact solution to the boundary value problem corresponding to the uncracked steel–rust–concrete composite was possible. After appearance of the microcracks the concrete behavior becomes nonlinear anisotropic with post-cracking softening, and the associated problem is analytically intractable. Therefore, it is proposed to employ a novel meshless method, namely gradient reproducing kernel particle (GRKPM), in the cylindrical coordinates. The analytical and numerical solutions pertinent to the uncracked concrete are in good agreement. Subsequently, the effects of the parameters associated with the mechanical behavior of concrete and properties of rust on the time of surface cracking, the maximum values of consumed rebar per unit area of anode and crack width openings at the time of surface cracking, and the maximum value of radial stress at the rust–concrete interface are scrutinized in some detail.     

An Upper Bound on Air Interface Blocking Probability in Multiservice CDMA Networks

We propose a novel approach to derive an upper bound for the air interface blocking probability in a multiservice CDMA network with soft handoff (SHO) as a function of network load. This method requires only general assumptions made for network design and dimensioning. We obtain an approximated upper bound and compare it with the calculated values for the upper bound and with real network simulation results to show that our method with a reduced computational complexity is also accurate.