Study on soliton phase characteristics in 100 Gbps single‐channel telecommunication system

Here, we demonstrate the peculiar particle nature of soliton pulses with relative to phase, where the adjacent soliton pulses in a sequence attract and repel each other periodically for in‐phase and out‐of‐phase arrangement, respectively. This effect of soliton's interaction and repulsion is studied analytically by using perturbation theory approach. The study of soliton pair characteristics are mainly noted for different relative spacing (q _o ) between them and for different phase of launched soliton pulses. Following the analytical studies, we analyzed the effect in a 100 Gbps, single channel and uncompensated telecommunication system for different phased soliton sequences. Such that, the performance of the telecommunication system is characterized in terms of Q‐factor (Q) and bit‐error rate to realize the influence of phase on soliton pulses. The system was studied for 1 collision length (L _D ) of 123.36 km. It is seen that, for 100 Gbps system implemented with standard single mode telecom fiber, with soliton spaced at q _o  = 5.28, the in‐phase pulses interacted at 61.68 km, which has resulted in Q  = 0 (bit‐error rate  = 1). It is realized that for small‐phase introduction on soliton pulses, the system yielded fair Q demonstrating the non‐interaction at the I _p as the pulses deviate with respect to increasing phase values. But, it is also shown that large phase between pulses introduces more deviation, which results in overlapping of deviated pulses with adjacent pulses in sequence resulting in degradation of high bitrate system performance.     

Theoretical Study of Interplay of Superconductivity and Ferromagnetism in Hybrid Rutheno–Cuprate Superconductors RuSr2RCu2O8

We consider the extended two-band s–f model with additional terms, describing intersite Cooper pairs’ interaction between 4f (5f) and conduction electrons. Following Green’s function technique and equation of motion method, self-consistent equations for superconducting order parameter (Δ) and magnetic order parameter (m _f ) are derived. The expressions for specific heat, density of states, and free energy are also derived. The theory has been applied to explain the coexistence of superconductivity and ferromagnetism in hybrid rutheno-cuprate superconductors RuSr₂RECu₂O₈ (RE = Gd, Eu). The theory shows that it is possible to become superconducting if the system is already ferromagnetic. A study of specific heat, density of states and free energy is also presented. The agreement between theory and experimental observations is quite satisfactory.      

Three-dimensional analysis of load transfer micro-mechanisms in fibre/matrix composites

This study gives a detailed analysis of load distributions around fibre breaks in a composite. In contrast to other studies reported in the literature, the analysis considers different configurations of composite damage from the failure of a few to the failure of many fibres. The model considers three types of matrix behaviours (elastic, elastic–plastic and viscoelastic) with or without debonding at the broken fibre/matrix interface. In this way, the usual limitations of the finite element approach are overcome so as to take into account the number and interactions of broken fibres whilst maintaining an evaluation of the various fields (stresses in particular).     

Hydrogen‐bonding interaction between poly(ε‐caprolactone) and low‐molecular‐weight amino compounds

The specific interactions between several low‐molecular‐weight diamino compounds and poly(ε‐caprolactone) (PCL) have been investigated by FT‐IR. It was found that PCL and 3,3′‐diaminodiphenylmethane (3,3′‐DADPM) interact through strong intermolecular hydrogen bonds in the blend. Thermal and mechanical properties of PCL/3,3′‐DADPM blends were investigated by DSC and tensile measurements, respectively. The glass transition temperature of the blend increases while both the melting point and the elongation‐at‐break of the blend decrease with the increase of 3,3′‐DADPM content. Besides 3,3′‐DADPM, several other low‐molecular‐weight compounds containing two amino groups, such as o‐phenylenediamine or 1,6‐diaminohexane, were also added into PCL and the corresponding blend systems were investigated by FT‐IR and DSC. The effect of the chemical structure of the additives on the properties of PCL is discussed. © 2001 Society of Chemical Industry     

A mesh adaptation framework for dealing with large deforming meshes

In this paper, we identify and propose solutions for several issues encountered when designing a mesh adaptation package, such as mesh‐to‐mesh projections and mesh database design, and we describe an algorithm to integrate a mesh adaptation procedure in a physics solver. The open‐source MAdLib package is presented as an example of such a mesh adaptation library. A new technique combining global node repositioning and mesh optimization in order to perform arbitrarily large deformations is also proposed. We then present several test cases to evaluate the performances of the proposed techniques and to show their applicability to fluid–structure interaction problems with arbitrarily large deformations. Copyright © 2009 John Wiley & Sons, Ltd.     

计算机辅助教学对英语教学的影响

多媒体设备走进课堂,是教育形式的一次伟大变革,并已强势占领了课堂,给我们带来了教育质量的提升和教学模式的优化。与此同时,它又悄无声息地对英语教学产生了一些影响。回顾了计算机进入课堂的意义和优势,并基于英语教学的特点,论述了教授者滥用计算机辅助设备给英语教学带来的影响及解决的策略。     

Depression of melting point of eutectic metal alloy by the interaction with polyacrylates in metal-polymer composites

The composites of polyacrylates and eutectic metal alloy composed by Bi, In, and Sn were prepared by mixing the metal and polymer above the melting point of the metal alloy (80 °C) with a homogenizer. Two melting peaks, which were assigned as the melting peak of the original metal alloy and that of the interfacial phase of the metal alloy interacting with polyacrylates (70 °C) by differential scanning calorimetry. Metal particles with the diameter of about 100 nm which were stabilized by the interfacial interaction with polyacrylates were observed by transmission electron microscopy. The melting peak at 70 °C was assigned as the melting peak of these small particles.     

Interaction of main‐chain polycations with sodium dodecyl sulfate

The interaction of the main‐chain polycations 2,2‐ionene (I_2,2) and 3,3‐ionene (I_3,3) with sodium dodecyl sulfate (SDS) has been investigated in aqueous solution. It was confirmed that the interaction is cooperative and a stoichiometric 1:1 complex of I_2,2–SDS or I_3,3–SDS with regular structure forms as a precipitate irrespective of the molar ratio of the components. It is completely different from the interaction of side‐chain polycations such as the poly[(vinyl pyridine)‐co‐styrene] copolymer cation (PVSC) with SDS, in which no cooperative effect was observed. The driving force responsible for the cooperative effect is believed to be the hydrophobic attraction between the SDS molecule already linked on the ionene chain and the next SDS molecule to be entered. It was also confirmed that the structures of the complexes are very different, ie the ionene–SDS complexes exhibit high regularity whereas the PVSC–SDS complex is irregular. © 2001 Society of Chemical Industry     

Homogeneous complex solution formed through interactions of poly(acrylamide‐co‐acrylic acid)/poly(acrylamide‐co‐dimethyldiallylammonium chloride) complex with M n+ hydration metal ions in aqueous media

A homogeneous complex solution, formed through inter‐polyelectrolyte complexation of poly(acrylamide‐co‐acrylic acid) (P(AM‐AA)) with poly(acrylamide‐co‐dimethyldiallylammonium chloride) (P(AM‐DMDAAC)) and interaction of the P(AM‐AA)/P(AM‐DMDAAC) complex with M ⁿ⁺ hydrated metal ion, was prepared and the structure and properties of the P(AM‐AA)/P(AM‐DMDAAC)/M ⁿ⁺ homogeneous complex solution were studied by UV spectrometry, dynamic light scattering and viscometry. The experimental results show that the homogeneous complex solution can be obtained by controlling the composition of the P(AM‐AA)/P(AM‐DMDAAC) complex and the M ⁿ⁺ metal ion content. Compared to the constituents, ie the P(AM‐AA) solution, the P(AM‐DMDAAC) solution and the P(AM‐AA)/P(AM‐DMDAAC) complex solution, the P(AM‐AA)/P(AM‐DMDAAC)/M ⁿ⁺ complex solution has a new peak at 270 nm in its UV spectrum, a larger hydrodynamic radius, and hence a higher solution viscosity, all of which indicate that there exist specific interactions between polymers and M ⁿ⁺ metal ions. These interactions lead to the formation of a network structure and hence an obvious increase not only in solution viscosity but also in resistance of the polymer solution to simple salts, to temperature changes and to shearing. © 2001 Society of Chemical Industry     

An investigation on the sensitivity analysis of the parameters of proposed wax precipitation model

Reservoir hydrocarbon fluids contain heavy paraffins that may form solid phase of wax at low temperatures. Formation of solid phases is highly unwanted in oil production assemblies, pipelines and in process equipments. A predictive technique is crucial to the solution of wax formation to alleviate this problem.The effect of different parameters to predict the conditions under which wax precipitation takes place using the proposed model of Sahand University of Technology and other models has been investigated. The proposed model uses regular solution theory to describe solid phase (wax) non-ideality and the liquid and gas phases are being described by an equation of state.In order to evaluate the reliability of the proposed model, wax appearance temperatures (WAT's) were calculated for several mixtures at different compositions and compared with different models. The proposed model predictions had very good agreement with experimental data over a wide range of compositional distributions in comparison with other models. Solid wax content was also calculated at different temperatures below WAT in several synthetic systems made up of a solvent (decane) and a paraffinic heavy fraction. The results of calculating the amount of wax precipitation showed very good agreement with experimental data. Effect of different parameters including fusion temperature (T^f), Enthalpy of fusion (Δh^f), solubility parameter (δ^S), and binary interaction parameters (BIP) in predicting the WAT and the amount of wax precipitated for different oil mixtures have been evaluated using the proposed model and compared with other models. The results showed that the T^f is the most sensitive parameter while δ^S shows the least sensitivity in matching the WAT. Even though using Δh^f could provide the same results as tuning T^f, but the required changes are much higher and sometimes not practical. Also using BIP as the tuning parameter, requires a fairly large coefficient that makes it unsuitable to be considered as the tuning parameter.