Packet data transmission over mobile radio channels

Since in mobile radio Rayleigh fading poses the main threat to accurate data transmission, a mathematical model of the dynamics of Rayleigh fading is used to explore the optimum duration of data packets. The performance criterion is the rate of information transfer through the mobile radio channel. In addition to packet size, the information rate depends on: the speed of the mobile terminal, the channel bit rate, the size of the packet header, and the fade margin of the modulation and coding techniques. In particular, attention is focused on line rates of 16 kb/s and 256 kb/s (which are representative of the rates proposed for digital mobile radio systems in North America and Europe, respectively). At 16 kb/s, the optimum packet size is approximately 17 B (8.5-ms duration). At 256 kb/s, maximum throughput occurs when the packet contains about 48 B (1.5-ms duration). The precise optimum depends on vehicle speed, header size, and fade margin. The optimum packets are considerably shorter than the 125-B packets customarily used in terrestrial and satellite systems     

Digital correction method for an H-field sensor in power system EMC measurements

Analysis was conducted on the nature and characteristics of an H-field sensor for power system electromagnetic compatibility (EMC) measurements. Based on the original calibrated response curve of the magnetic-field (H) sensor and steepest descent theory, an analog model has been created to represent the sensor's transfer function. This function was converted into a set of digital algorithms by the bilinear transformation method, thus allowing subsequent signal processing on available software. The digital correction model for the sensor gives an estimated error of within 8% for all the relevant frequency components. The results present some general analysis methods for power system EMC measurements.     

Innovative Practices for IT Projects

Abstract

Based on 57 interviews with senior IT project managers in the UK Canada, USA and New Zealand, this article presents innovative practices they have developed during difficult projects. In our respondents' view, traditional project management methods and techniques are only a starting point. Through their quotes, they show how one has to be creative and entrepreneurial to lead projects successfully.     

Alternative framework for assessing sustainable building funds: Green Building Fund

The Green Building Fund (GBF) established in 2008 as part of the Clean Business Australia initiative is aimed at mitigating the risk of climate change by forming close partnerships between government, business and industry. It is specifically targeted to reduce the impact of the built environment on Australia's greenhouse gas (GHG) emissions by reducing energy consumption through the operation of commercial office buildings. As part of the selection process, projects are assessed against three merit criteria: the potential reduction in GHG emissions, demonstration of potential, and quality of project design and management. An alternative framework is proposed that contributes more rigour to the current selection process. In particular, it contends for the use of second-order moment and Markov chain to establish the present worth and feasibility of green investment where the underlying parameters of interest/discount rate and cash flows (in terms of savings) are uncertain. This framework will be useful not only to AusIndustry (the funding body of the GBF) and other government departments worldwide responsible for awarding green building funds but also to owners who are keen on strengthening their application by improving the demonstration of project feasibility.     

Client strategies in vendor transition: A threat balancing perspective

Many outsourcing contracts are expiring, and vendor transition is an increasing concern. This paper attempts to develop guidelines for vendor transition by applying balance of threat theory, which suggests a client organization should pursue either a “soft” or “hard” balancing strategy, depending on the outgoing vendor’s capability and aggressive intent to disrupt client operations. Balance of threat theory is explored across two contrasting case sites. In addition to demonstrating the relevance of balance of threat theory, the cases identify specific tactics associated with hard and soft balancing, as well as key areas of conflict in vendor transition.     

Enhanced CO<Subscript>2</Subscript> electroreduction on armchair graphene nanoribbons edge-decorated with copper

Inspired by the recent experimental synthesis of graphene nanoribbons (GNRs) and theoretical research on their edge-decoration,we comprehensively studied the electrocatalytic performance of GNRs edge-decorated with Cu for CO2 reduction.Compared to zigzag GNRs,the Cu-terminated armchair GNRs with a width of n =3p + 2 were more efficient catalystsforproducing methanol from CO2 with a free energy barrier of less than 0.5 eV,offering the advantages of a lower overpotential and higher selectivity than bulk Cu and other graphene-supported Cu structures.On the other hand,the competing hydrogen evolution reaction could be effectively suppressed by Cu-terminated armchair GNRs.Hence,the edge-decorated GNRs offer great flexibility for tuning the catalytic efficiency and selectivity for CO2 electroreduction.     

Enhanced adsorption of anionic phenol red using cationic polyethylenimine-incorporated chitosan beads

Journal of Porous Materials - In this study, a fast and simple dissolution and coagulation method was adopted to produce polyethylenimine (PEI)-incorporated chitosan beads. The beads were...     

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