Flow and Velocity Distribution in Meandering Compound Channels

An investigation of flow and velocity distribution in meandering compound channels with over bank flow is described. Equations concerning the three-dimensional variation of longitudinal, transverse, and vertical velocity in the main channel and floodplain of compound section in terms of channel parameters are presented. The flow and velocity distributions in meandering compound channels are strongly governed by interaction between flow in the main channel and that in the floodplain. The proposed equations take adequate care of the interaction affect. Results from the formulations, simulating the three-dimensional velocity field in the main channel and in the floodplain of meandering compound channels are compared with their respective experimental channel data obtained from a series of symmetrical and unsymmetrical test channels with smooth and rough sections. The aspect ratio of the test channels varies from two to five. The equations are found to be in good agreement with the experimental data. The formulations are verified against the natural river and other meandering compound channel data. The power laws used for simulating the three-dimensional velocity structure are found to be quite adequate.     

Research and innovation in South African universities: from the triple helix’s perspective

Different from most prior research studying the influence of networks on scientific knowledge creation by taking on a single social-based perspective, this study offers an integrated frame based upon both social-based and knowledge-based views. This study incorporates quantitative bibliometric methods of analysis and network analysis. Based on 51,972 alternative energy patents in 1998–2012, we build knowledge networks composed of technological classifications and social networks capturing collaborations. Based on patent citation networks, we use citations in every period to calculate researcher’s knowledge creation performance. We hypothesize that centrality of researchers in the knowledge network and their knowledge creation display an inverted-U relationship. What’s more, we propose that this curvilinear relation is moderated by their structural holes and centrality in the collaboration network. Based on the negative binomial model with fixed effects and robust tests, results indicate that (1) locations of the researchers in knowledge network contribute more to knowledge creation when their centrality is moderate, rather than high or low; (2) at a moderate level of knowledge network centrality, the researchers, who occupy more central positions or span more structural holes in collaboration network, will benefit more than the ones who do not. The findings of this research, besides having implications for research on knowledge networks, have implications on scientometric indicators, multiple networks study, and knowledge creation process.     

FGFS: Feature Guided Frontier Scheduling for SIMT DAGs

In the past decade, heterogeneous multicore architectures with support for Single Instruction Multiple Thread (SIMT) style computing have become the standard platform of choice for scheduling HPC applications. Here, applications are typically modelled as a set of data-parallel tasks with dependencies represented in the form of a directed acyclic graph (DAG). The relevant execution time information for each constituent task in the DAG is known beforehand and is leveraged by scheduling algorithms (List or Cluster based) to ascertain near-optimal schedules at runtime. However, given an online setting, where applications are submitted by multiple users and the types of applications are not restrictive, the chances of knowing execution time information for every program are highly unlikely. In this context, we propose a class of intelligent algorithms for heterogeneous CPU-GPU platforms that leverage static analysis-assisted machine learning techniques for deciding how device assignments should be made at runtime, thus bypassing the requirement for expensive offline profiling passes. We formalize relevant task-level ranking metrics and discuss how existing scheduling techniques can be adapted for our proposed class of algorithms. We also devise an online cluster scheduling algorithm that supports dynamic task arrival by determining in any given scheduling epoch, mapping decisions for a subset of tasks in a DAG. We perform a detailed comparative analysis between our proposed cluster and list scheduling heuristics via extensive simulation experiments using a variety of heterogeneous multicore platform configurations and observe performance speedups in the range of 1.1–1.5× for cluster scheduling over that of list scheduling.

     

A TM03 mode reduced side lobe high‐gain printed antenna array in K band for UDN and IoT applications in 5G

A single layer simple feed reduced side lobe gain‐enhanced microstrip antenna array using higher‐order modes is analyzed and designed in this work. The relationship between the relative magnitude of equivalent magnetic currents and directivity are studied. Modal analysis for rectangular patch is considered for broadside and non‐broadside radiation. Comparative investigations on antenna radiation and impedance characteristics for fundamental and higher‐order modes are presented. It is observed that an array can be designed to operate in TM₀₃ mode for enhanced gain with broadside radiation. Parametric optimization is carried out to attain low side lobe level. The proposed theory is validated by designing and fabricating a single layer single feed 2 × 2 microstrip patch array in the K band operating in TM₀₃ mode. The simulated and measured realized gain of the fabricated TM₀₃ mode array is 16.1 and 15.5 dBi, respectively, at 22 GHz with consistent broadside radiation pattern and linear polarization.     

Outage probability bound of decode and forward two‐way full‐duplex relay employing spatial modulation over cascaded α − μ channels

The system performance of mobile‐to‐mobile (D2D) cooperative communication has been improved by utilizing spatial modulation (SM) in this paper. The proposed system employs decode and forward (DF) relaying technique along with physical layer network coding (PLNC); hence, it has been named as SM‐based decode and forward two‐way relay (DFTWR). It enables full‐duplex communication thereby enhancing the system efficiency. Information bits are exchanged between the two bidirectional nodes. For two bits of information exchange, the antenna index is conveyed by the least significant bit (LSB) of the data symbol while the most significant bit (MSB) carries the message. The system performance has been investigated by analyzing certain performance metrics like lower and upper bounds of outage probability and average data rate for N‐α‐μ cascaded fading channels. The change in the system performance by varying certain parameters like relative geometrical gain, fading coefficients, and number of cascaded components has also been put forth in this paper.     

Micro-scale thermo-fluidic transport in two immiscible liquid layers subject to combined electroosmotic and pressure-driven transport

A theoretical analysis is presented for fully developed convective heat transfer in two immiscible fluid layers confined within parallel plate microchannels subject to combined effects of axial pressure gradients and imposed electrical fields. Assuming desperate zeta potentials at the interfaces thus formed, closed-form expressions are derived for the velocity and temperature distributions under fully developed conditions, with uniform wall heat flux boundary conditions. For the heat transfer analysis, the viscous dissipation effects are neglected as compared to the Joule heating effects. Results are subsequently obtained for different ranges of the ratios of various electrical properties of the two fluid layers and various relative strengths of the ratios of the electrical fields and the imposed pressure gradients. These results demonstrate the effects of the applied electric fields and pressure gradients, presence of external heat source or sink and interfacial positions on the temperature distributions in the two layers and the corresponding Nusselt numbers.     

Non-linear channel equalization using adaptive MPNN

In this paper the Modified Probabilistic Neural Network (MPNN) is used for dealing with the problem of channel equalization. Some improvements are suggested for the MPNN so that it is more suitable for the current problem. Firstly, the MPNN is extended to process complex signals. Secondly, a stochastic gradient adaptation technique is proposed, such that when the network is being employed to equalize a slowly varying channel, it can self-adapt to the changing environment. Simulations have shown that the MPNN is able to effectively equalize 4-QAM symbol sequences transmitted through a non-linear, slowly time-varying channel. Finally, methods that further reduce the size of the network are proposed. Simulations show that the proposed method is able to reduce the size of the network considerably.     

Optical properties of undoped and oxygen doped CuCl films on silicon substrates

Semiconductor photonic emitters operating in the UV range remain an elusive goal. Attention has focused mainly on III-Nitrides. However, a large lattice constant difference between the III-Nitride layers and the compatible substrates results in high densities of misfit dislocations and consequently the device performance is adversely affected. An alternative novel material system, γ-CuCl on silicon, is investigated. Properties of the exciton luminescence from vacuum deposited undoped and oxygen doped CuCl films on Si are studied using temperature dependent photoluminescence spectroscopy. Oxygen doping degrades the optical quality and introduces an intermediate state leading to negative thermal quenching behaviour.