Blurring the boundaries: Prosumption, circularity and online sustainable consumption through Freecycle

© The Author(s) 2015. This article explores the digital exchange and moral ordering of sustainable and ethical consumption in online Freecycle groups. Through interactive exchanges in digital (online posts) and material (consumer items) modes, Freecycling blurs three common binaries in analyses of consumption: (1) consumption/production, (2) digital/material and (3) mainstream/alternative. Drawing on Ritzer's notion of 'implosions' as well as practice theory, I show that Freecycling practices reimagine and reproduce both products and consumers, practising prosumption through mixed digital and material practices in a performative economy, and how mainstream and alternative ways of consuming are entangled in pursuit of more sustainable, ethical consumption. This challenges us to think beyond these traditional binaries and to conceptualise a more blurred, less analytically clean and more circular approach to studying consumption

Low Power Analog-to-Digital Conversion in Millimeter Wave Systems: Impact of Resolution and Bandwidth on Performance

The wide bandwidth and large number of antennas used in millimeter wave systems put a heavy burden on the power consumption at the receiver. In this paper, using an additive quantization noise model, the effect of analog-digital conversion (ADC) resolution and bandwidth on the achievable rate is investigated for a multi-antenna system under a receiver power constraint. Two receiver architectures, analog and digital combining, are compared in terms of performance. Results demonstrate that: (i) For both analog and digital combining, there is a maximum bandwidth beyond which the achievable rate decreases; (ii) Depending on the operating regime of the system, analog combiner may have higher rate but digital combining uses less bandwidth when only ADC power consumption is considered, (iii) digital combining may have higher rate when power consumption of all the components in the receiver front-end are taken into account.Comment: 8 pages, 6 figures, in Proc. of IEEE Information Theory and Applications Workshop, Feb. 201

Analog-to-digital converter has increased reliability and reduced power consumption

Eight-bit analog-to-digital converter decreases average power consumption and increases component reliability. The converter uses solid-state components in pulse operation and magnetic core components for minimizing power consumption. The magnetic core components also increase reliability

Individual flip-flops with gated clocks for low power datapaths

Energy consumption has become one of the important factors in digital systems, because of the requirement to dissipate this energy in high-density circuits and to extend the battery life in portable systems such as devices with wireless communication capabilities. Flip-flops are one of the most energy-consuming components of digital circuits. This paper presents techniques to reduce energy consumption by individually deactivating the clock when flip-flops do not have to change their value. Flip-flop structures are proposed and selection criteria given to obtain minimum energy consumption. The structures have been evaluated using energy models and validated by switch-level simulations. For the applications considered, significant energy reductions are achieved.Peer ReviewedPostprint (published version

The digital-only media consumer: Key findings from a conversation with all-digital millenials

This study offers insight on the digital-onlys, a sub-population of Millennials who only consume media through digital platforms. Based on informal group conversations with 16 to 34 year-olds, the study provides a snapshot of their daily media consumption and preliminary answers to why they regard digital content as the norm. These findings reveal that some consumers today are not simply abandoning traditional platforms and turning towards digital content, they actually seem to know no other way to consume media but on digital platforms. For them, the biggest consumption change would actually be to watch cable television, listen to FM radio or read a printed newspaper or magazine. Digital-onlys may represent a new kind of consumers that view their media habits as completely normal and organic. Indeed, some are not even aware they belong to this digital group. The participants shared common characteristics: an ability to adapt devices to their needs, an intrinsically digital lifestyle and a habit of bypassing traditional media to access a larger selection of content despite the fact they’re struggling with an overabundance of choice. Our conversations also revealed that digital-onlys are fully aware of the negative impact their media consumption habits can have on content creators, yet they cherish freedom above all else

Consumption Taxation in a Digital World: A Primer

The paper reviews the economic and administrative issues that arise in the taxation of electronic commerce; addresses how best to meet the criteria of an ideal tax system; and examines recent policy developments.It is argued that destination-based taxation-is presently the norm for goods taxation is technically more complex for digital products and intangible services sold over the Internet, reflecting the difficulty of determining the location of the buyer and seller.Most of the potential solutions to this problem require a great deal of administrative cooperation between national tax authorities.Case studies of several countries show that policy responses to electronic commerce have di.ered, with the European Union taking the lead on implementing a system of destination-based registration.Destination principle;international consumption taxation;electronic commerce;origin taxation;cross-border trade

An audio FIR-DAC in a BCD process for high power Class-D amplifiers

A 322 coefficient semi-digital FIR-DAC using a 1-bit PWM input signal was designed and implemented in a high voltage, audio power bipolar CMOS DMOS (BCD) process. This facilitates digital input signals for an analog class-D amplifier in BCD. The FIR-DAC performance depends on the ISI-resistant nature of this PWM-signal. An impulse response with only positive coefficients was chosen, because of its resistance to deadzone and mismatch. With a DAC current of 0.5 mA, the dynamic range is 111 dB (A-weighted), with SINAD = 103 dB (A-weighted). The current consumption is 1mA for the analog part and 4.8 mA for the digital part. The power consumption is 29 mW at V/sub dd/ = 5 V and the chip area is 2 mm/sup 2/ including the reference diode that can be shared by more channels

Hybrid MIMO Architectures for Millimeter Wave Communications: Phase Shifters or Switches?

Hybrid analog/digital MIMO architectures were recently proposed as an alternative for fully-digitalprecoding in millimeter wave (mmWave) wireless communication systems. This is motivated by the possible reduction in the number of RF chains and analog-to-digital converters. In these architectures, the analog processing network is usually based on variable phase shifters. In this paper, we propose hybrid architectures based on switching networks to reduce the complexity and the power consumption of the structures based on phase shifters. We define a power consumption model and use it to evaluate the energy efficiency of both structures. To estimate the complete MIMO channel, we propose an open loop compressive channel estimation technique which is independent of the hardware used in the analog processing stage. We analyze the performance of the new estimation algorithm for hybrid architectures based on phase shifters and switches. Using the estimated, we develop two algorithms for the design of the hybrid combiner based on switches and analyze the achieved spectral efficiency. Finally, we study the trade-offs between power consumption, hardware complexity, and spectral efficiency for hybrid architectures based on phase shifting networks and switching networks. Numerical results show that architectures based on switches obtain equal or better channel estimation performance to that obtained using phase shifters, while reducing hardware complexity and power consumption. For equal power consumption, all the hybrid architectures provide similar spectral efficiencies.Comment: Submitted to IEEE Acces

Energy-aware MPC co-design for DC-DC converters

In this paper, we propose an integrated controller design methodology for the implementation of an energy-aware explicit model predictive control (MPC) algorithms, illustrat- ing the method on a DC-DC converter model. The power consumption of control algorithms is becoming increasingly important for low-power embedded systems, especially where complex digital control techniques, like MPC, are used. For DC-DC converters, digital control provides better regulation, but also higher energy consumption compared to standard analog methods. To overcome the limitation in energy efficiency, instead of addressing the problem by implementing sub-optimal MPC schemes, the closed-loop performance and the control algorithm power consumption are minimized in a joint cost function, allowing us to keep the controller power efficiency closer to an analog approach while maintaining closed-loop op- timality. A case study for an implementation in reconfigurable hardware shows how a designer can optimally trade closed-loop performance with hardware implementation performance