764 research outputs found
Political Shaping Of Transitions To Biofuels In Europe, Brazil And The USA
Faced with major challenges of global climate change, declining fossil fuel reserves, and competition between alternative uses of land, the transition to renewable transport fuels has been marked by new modes of political economic governance and the strategic direction of innovation. In this paper, we compare the different trajectories to the development and uptake of biofuels in Europe, Brazil and the USA. In terms of the timing, direction, and development of biofuels for road transport, the early lead taken by Brazil in sugarcane based ethanol and flex-fuel cars, the USA drive to corn-to-ethanol, and the European domination of biodiesel from rapeseed, manifest significant contrasts at many levels. Adopting a neo-Polanyian ?instituted economic process? approach we argue that the contrasting trajectories exemplify the different modes of politically instituting markets. We analyse the contrasting weight and impact of different drivers in each case (energy security, climate change mitigation, rural economy development, and market opportunity) in the context of diverse initial conditions and resource endowments. We explore the ?politics of markets? that arise from the different modes of instituting markets for ecologically sustainable economic growth, including the role of NGOs, the scientific controversies over land-use change, and the contrasting political institutions in our case studies. We also place our analysis in the historical perspective of other major carbon energy transitions (charcoal to coal, coal to petrochemicals). In so doing, we explore the idea of the emergence of new modes of governance of contemporary capitalist political economies, and the significance of politically directed innovation. The research is based on an extensive primary research programme of in-depth interviews with strategic players in each of the geographic regions, qualitative institutional analysis, a scenario workshop, and secondary data analysis
Public or private economies of knowledge: The economics of diffusion and appropriation of bioinformatics tools
The past three decades have witnessed a period of great turbulence in the economies of biological knowledge, during which there has been great uncertainty as to how and where boundaries could be drawn between public or private knowledge especially with regard to the explosive growth in biological databases and their related bioinformatic tools. This paper will focus on some of the key software tools developed in relation to bio-databases. It will argue that bioinformatic tools are particularly economically unstable, and that there is a continuing tension and competition between their public and private modes of production, appropriation, distribution, and use. The paper adopts an ?instituted economic process? approach, and in this paper will elaborate on processes of making knowledge public in the creation of ?public goods?. The question is one of continuously creating and sustaining new institutions of the commons. We believe this critical to an understanding of the division and interdependency between public and private economies of knowledge
A selective control information detection scheme for OFDM receivers
In wireless communications, both control information and payload (user-data) are concurrently transmitted and required to be successfully recovered. This paper focuses on block-level detection, which is applicable for detecting transmitted control information, particularly when this information is selected or chosen from a finite set of information that are known at both transmitting and receiving devices. Using an orthogonal frequency division multiplexing architecture, this paper investigates and evaluates the performance of a time-domain decision criterion in comparison with a form of Maximum Likelihood (ML) estimation method. Unlike the ML method, the proposed time-domain detection technique requires no channel estimation as it uses the correlation (in the time-domain) that exists between the received and the transmitted selective information as a means of detection. In comparison with the ML method, results show that the proposed method offers improved detection performance, particularly when the control information consists of at least 16. However, the implementation of the proposed method requires a slightly increased number of mathematical computations
A low complexity SI sequence estimator for pilot-aided SLM–OFDM systems
Selected mapping (SLM) is a well-known method for reducing peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. However, as a consequence of implementing SLM, OFDM receivers often require estimation of some side information (SI) in order to achieve successful data recovery. Existing SI estimation schemes have very high computational complexities that put additional constraints on limited resources and increase system complexity. To address this problem, an alternative SLM approach that facilitates estimation of SI in the form of phase detection is presented. Simulations show that this modified SLM approach produces similar PAPR reduction performance when compared to conventional SLM. With no amplifier distortion and in the presence of non-linear power amplifier distortion, the proposed SI estimation approach achieves similar data recovery performance as both standard SLM–OFDM (with perfect SI estimation) and also when SI estimation is implemented through the use of an existing frequency-domain correlation (FDC) decision metric. In addition, the proposed method significantly reduces computational complexity compared with the FDC scheme and an ML estimation scheme
A joint OFDM PAPR reduction and data decoding scheme with no SI estimation
The need for side information (SI) estimation poses a major challenge when selected mapping (SLM) is implemented to reduce peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. Recent studies on pilot-assisted SI estimation procedures suggest that it is possible to determine the SI without the need for SI transmission. However, SI estimation adds to computational complexity and implementation challenges of practical SLM-OFDM receivers. To address these technical issues, this paper presents the use of a pilot-assisted cluster-based phase modulation and demodulation procedure called embedded coded modulation (ECM). The ECM technique uses a slightly modified SLM approach to reduce PAPR and to enable data recovery with no SI transmission and no SI estimation. In the presence of some non-linear amplifier distortion, it is shown that the ECM method achieves similar data decoding performance as conventional SLM-OFDM receiver that assumed a perfectly known SI and when the SI is estimated using a frequency-domain correlation approach. However, when the number of OFDM subcarriers is small and due to the clustering in ECM, the modified SLM produces a smaller PAPR reduction gain compared with conventional SLM
Monitoring contamination level on insulator materials under dry condition with a microwave reflectometer
Current techniques used for monitoring the levels of contamination on high voltage insulators, such as leakage current and infrared, are not effective in dry conditions since they require the surface of the insulator to be wetted by fog, rain or snow. If a buildup of contamination occurs during a prolonged dry period prior to a weather change there will be a significant risk that flashover may occur before there is time to implement preventative maintenance. Previous work has demonstrated the use of microwave radiometry to determine the levels of contamination on an insulator material under dry conditions, however practical applications are limited by low sensitivity. This paper reports the development of a novel technique based on microwave reflectometry to detect the power levels reflected from the surface of the insulator material. The level of contamination is then determined as a function of received power. A theoretical model establishes the relationship between equivalent salt deposit density levels on insulator surface and the dielectric properties of the contamination layer. A Finite Difference Time Domain (FDTD) model is used to simulate the total loss as a function of the contamination level. Experimental results verify the FDTD model and demonstrate the sensitivity of the reflectometer system to be approximately 100 times greater than the radiometer system. Therefore, the reflectometry system has considerably greater potential for practical applications to provide advance warning of the future failure of insulators under dry conditions for both HVDC and HVAC systems
Feasibility study on application of microwave radiometry to monitor contamination level on insulator materials
This paper introduces a novel method for monitoring contamination levels on high voltage insulators based on microwave radiometry. Present contamination monitoring solutions for high voltage insulators are only effective in predicting flashover risk when the contamination layer has been wetted by rain, fog or condensation. The challenge comes where the pollution occurs during a dry period prior to a weather change. Under these conditions, flashover can often occur within a short time period after wetting and is not predicted by measurements taken in the dry period. The microwave radiometer system described in this paper measures energy emitted from the contamination layer and could provide a safe, reliable, contactless monitoring method that is effective under dry conditions. The relationship between equivalent salt deposit density and radiometer output is described using a theoretical model and experimentally verified using a specially designed X-band radiometer. Results demonstrate that the output from the radiometer is able to clearly distinguish between different levels of contamination on insulator materials under dry conditions. This novel contamination monitoring method could potentially provide advance warning of the future failure of wet insulators in climates where insulators can experience dry conditions for extended periods
A reconfigurable real-time morphological system for augmented vision
There is a significant number of visually impaired individuals who suffer sensitivity loss to high spatial frequencies, for whom current optical devices are limited in degree of visual aid and practical application. Digital image and video processing offers a variety of effective visual enhancement methods that can be utilised to obtain a practical augmented vision head-mounted display device. The high spatial frequencies of an image can be extracted by edge detection techniques and overlaid on top of the original image to improve visual perception among the visually impaired. Augmented visual aid devices require highly user-customisable algorithm designs for subjective configuration per task, where current digital image processing visual aids offer very little user-configurable options. This paper presents a highly user-reconfigurable morphological edge enhancement system on field-programmable gate array, where the morphological, internal and external edge gradients can be selected from the presented architecture with specified edge thickness and magnitude. In addition, the morphology architecture supports reconfigurable shape structuring elements and configurable morphological operations. The proposed morphology-based visual enhancement system introduces a high degree of user flexibility in addition to meeting real-time constraints capable of obtaining 93 fps for high-definition image resolution
Unbalanced chemical equations conversion to Mark-up format and representation to vision impaired students
This paper describes a method to represent unbalanced chemical equations to vision impaired students which allows them to navigate through classified data, such as species, elements, quantity numbers at the left and right hand sides of equations, reactants, and products. Then they can find appropriate coefficients and balance chemical equations without involving to mathematical aspects of balancing and remembering a lot of information. The goal of this research was the development of an application which assists vision impaired students enrolled in chemistry course to be able to read chemistry literature containing formulae, chemistry representations of elements, and other aspects of chemistry that has been difficult in the past to present in a way for vision impaired people to understand. Developed application by this research is an open source command line Bash Script application under Linux which accepts an unbalanced chemical equation as an input, processes, classifies information, and represents it as Mark-up format or Alternative Audio Descriptive using Text to Speech
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