Green process innovation: Where we are and where we are going

Environmental pollution has worsened in the past few decades, and increasing pressure is being put on firms by different regulatory bodies, customer groups, NGOs and other media outlets to adopt green process innovations (GPcIs), which include clean technologies and end-of-pipe solutions. Although considerable studies have been published on GPcI, the literature is disjointed, and as such, a comprehensive understanding of the issues, challenges and gaps is lacking. A systematic literature review (SLR) involving 80 relevant studies was conducted to extract seven themes: strategic response, organisational learning, institutional pressures, structural issues, outcomes, barriers and methodological choices. The review thus highlights the various gaps in the GPcI literature and illuminates the pathways for future research by proposing a series of potential research questions. This study is of vital importance to business strategy as it provides a comprehensive framework to help firms understand the various contours of GPcI. Likewise, policymakers can use the findings of this study to fill in the loopholes in the existing regulations that firms are exploiting to circumvent taxes and other penalties by locating their operations to emerging economies with less stringent environmental regulations.publishedVersio

Three-Level De-Multiplexed Dual-Branch Complex Delta-Sigma Transmitter

In this paper, a dual-branch topology driven by a Delta-Sigma Modulator (DSM) with a complex quantizer, also known as the Complex Delta Sigma Modulator (CxDSM), with a 3-level quantized output signal is proposed. By de-multiplexing the 3-level Delta-Sigma-quantized signal into two bi-level streams, an efficiency enhancement over the operational frequency range is achieved. The de-multiplexed signals drive a dual-branch amplification block composed of two switch-mode back-to-back power amplifiers working at peak power. A signal processing technique known as quantization noise reduction with In-band Filtering (QNRIF) is applied to each of the de-multiplexed streams to boost the overall performances; particularly the Adjacent Channel Leakage Ratio (ACLR). After amplification, the two branches are combined using a non-isolated combiner, preserving the efficiency of the transmitter. A comprehensive study on the operation of this topology and signal characteristics used to drive the dual-branch Switch-Mode Power Amplifiers (SMPAs) was established. Moreover, this work proposes a highly efficient design of the amplification block based on a back-to-back power topology performing a dynamic load modulation exploiting the non-overlapping properties of the de-multiplexed Complex DSM signal. For experimental validation, the proposed de-multiplexed 3-level Delta-Sigma topology was implemented on the BEEcube™ platform followed by the back-to-back Class-E switch-mode power amplification block. The full transceiver is assessed using a 4th-Generation mobile communications standard LTE (Long Term Evolution) standard 1.4 MHz signal with a peak to average power ratio (PAPR) of 8 dB. The dual-branch topology exhibited a good linearity and a coding efficiency of the transmitter chain higher than 72% across the band of frequency from 1.8 GHz to 2.7 GHz