Data throughput is an important metric used in the performance evaluation of the next generation cellular networks such as long-term evolution (LTE) and LTE-advanced. To evaluate the performance of these networks, Monte Carlo simulation schemes are usually used. Such simulations do not provide the throughput of intermediate call state; instead it gives the overall performance of this network. The authors propose a hybrid model consisting of both analysis and simulation. The benefit of this model is that the throughput of any possible call state in the system can be evaluated. Here, the probability of possible call distribution is first obtained by analysis, which is used as input to the event-driven-based simulator to calculate the throughput of a call state. Comparison is made between throughput obtained from the author's hybrid model with that obtained from event-driven-based simulation. Numerical results are presented and show good agreement between both the proposed hybrid model and the simulation. The maximum difference of relative throughput between their hybrid model and the simulation is found in the interval of (0.04 and 1.06%) over a range of call arrival rates, mean holding times and number of resource blocks in the system.

A new hybrid technique based on hierarchical evolution is proposed for large, non-convex, multi-zone economic dispatch (MZED) problems considering all practical constraints. Evolutionary/swarm intelligence-based optimisation techniques are reported to be effective only for small/medium-sized power systems. The proposed hybrid hierarchical evolution (HHE) algorithm is specifically developed for solving large systems. The HHE integrates the exploration and exploitation capabilities of particle swarm optimisation and differential evolution in a novel manner such that the search efficiency is improved substantially. Most hybrid techniques export or exchange features or operations from one algorithm to the other, but in HHE their entire individual features are retained. The effectiveness of the proposed algorithm has been verified on six-test systems having different sizes and complexity levels. Non-convex MZED solution for such large and complex systems has not yet been reported.

The authors have realised a KTa _x Nb_{1− x} O₃-based optical beam scanner that has three- and five-pass configurations with internal reflection whose scanning angle is exactly proportional to the optical path length. They successfully increased the scanning angle to about 140 mrad with a 200 kHz modulation using a five-pass configuration. This beam scanner will provide an optical coherence tomography (OCT) system with a spatial resolution of 7 μm and advantages over other OCT systems.

An active quasi-circulator comprises three single-stage distributed amplifiers (DAs), in which two are for wideband transmission while the remaining one is for wideband signal cancellation. This quasi-circulator has wideband frequency operation and by optimising the bias current, tunable isolation enhancement between port 1 and port 3 is achieved. The experimental results show that this quasi-circulator has insertion losses of around 0 dB, return losses better than 10 dB at each port, minimum non-tunable isolation of around 15 dB from 0.8 to 2.2 GHz and tunable isolation of more than 40 dB between port 1 and port 3 from 0.8 to 2.2 GHz.

Knowledge of the discrete cosine transform coefficient distribution (DCT-DIST) is important for the encoder design. For example, rate control relies on this knowledge to estimate a possible bit rate and then decide proper coding parameters before the actual encoding task is performed. Therefore the rate control performance is fairly dependent on how accurately the DCT-DIST is modelled. The spatial enhancement layer (SL) DCT-DIST for H.264 scalable video coding (SVC) is studied in this Letter. SL DCT-DIST knowledge is furthermore used to derive a novel rate model. Our results can help design a proper rate control module for the H.264/SVC encoder.

A digital model which imitates the behaviour of a TiO₂ memristor as a new block in Alter DSP Builder is proposed in this Letter. The proposed model can be used as an independent memristor unit working with other units for designing memristor circuits based on field-programmable gate array. The accuracy of the digital model is confirmed not only by simulations, but also by hardwire experiments.

Quantum-dot cellular automata (QCA) is a novel nanotechnology which is considered as a solution to the scaling problems in complementary metal oxide semiconductor technology. In this Letter, a robust one layer crossover scheme is introduced. It uses only 90° QCA cells and works based on a proper clock assignment. The application of this new scheme is shown in designing a sample QCA circuit. Simulation results demonstrate that using this new scheme, significant improvements in terms of area and complexity can be achieved.

To alleviate the complex communication problems arising in the network-on-chip (NoC) architectures as the number of on-chip components increases, several novel interconnect infrastructures have been recently proposed to replace the traditional on-chip interconnection systems that are reaching their limits in terms of performance, power and area constraints. Wireless NoC (WiNoC) is among the most promising scalable interconnection architectures for future generation NoCs. In this study, the authors first provide a general description of the WiNoC architecture. Then, they discuss the research problems under five categories: topology, routing, flow control, antenna and reliability. Open research issues for the realisation of the WiNoC are also discussed.

The design and characteristics of double-gate (DG) junctionless (JL) devices are compared with the DG inversion-mode (IM) field effect transistors (FETs) at 45 nm technology node with effective channel length of 18 nm. The comparison are performed at iso-V _th for both n- and p-type of devices. The JL device shows lower drain-induced barrier lowering, steep subthreshold slope and lower OFF state current. For the first time, the authors demonstrate a pass gate (PG) logic, inverter circuit and static random access memory (SRAM) stability analysis using JL devices, rather than a complementary metal-oxide semiconductor (CMOS) configuration. They observed that transient response of JL PG configuration is similar to that of conventional CMOS PGs. JL inverter also shows similar transient characteristics with 25% reduction in delay and 12% improvement in 6 T SRAM cell stability compared with IMFETs, which shows large potential in digital circuit applications. The simulations were performed using coupled device-circuit methodology in ATLAS technology aided computer design (TCAD) mixed-mode simulator.

Engineering vehicle is widely used as a huge moving platform for transporting heavy goods. However, traditional human operations have a great influence on the steady movement of the vehicle. In this Letter, a fast reconstruction process of an unmanned engineering vehicle is carried out. By adding a higher-level controller and two two-dimensional laser scanners on the moving platform, the vehicle could perceive the surrounding environment and locate its pose according to extended Kalman filter. Then, a closed-loop control system is formed by communicating with the on-board lower-level controller. To verify the performance of automatic control system, the unmanned vehicle is automatically navigated when carrying a rocket towards a launcher in a launch site. The experimental results show that the vehicle could align with the launcher smoothly and safely within a small lateral deviation of 1 cm. This fast reconstruction presents an efficient way of rebuilding low-cost unmanned special vehicles and other automatic moving platforms.

Delay tolerant networks (DTN) are a class of networks that are a subset of the traditional mobile ad-hoc networks. It differs from mobile ad hoc networks (MANETs) in the sense that it can withstand high delays in delivering data because of frequent network partitions, limited bandwidth and storage constraints persisting in such networks. Owing to these inherent characteristics of the delay tolerant networks improving delivery ratio in such networks depends on two main factors-use of routing strategy and a good buffer management policy. Many routing protocols have been proposed in the literature for DTN. Buffer management is a very important factor in DTN because of the very limited buffer space available in DTN nodes. Although a scheduling policy in DTN determines which message has to be forwarded first, the dropping policy decides which messages are to be dropped in case of buffer overflow. This Letter presents a survey of the existing buffer management policies proposed for DTN and discusses the pros and cons of these approaches. The buffer management techniques have been classified on the basis of information used by them whether they are based on local information of messages available at the node or global information of all the messages in the network.