Multicast broadcast services support in OFDMA-based WiMAX systems [Advances in mobile multimedia]

Multimedia stream service provided by broadband wireless networks has emerged as an important technology and has attracted much attention. An all-IP network architecture with reliable high-throughput air interface makes orthogonal frequency division multiplexing access (OFDMA)-based mobile worldwide interoperability for microwave access (mobile WiMAX) a viable technology for wireless multimedia services, such as voice over IP (VoIP), mobile TV, and so on. One of the main features in a WiMAX MAC layer is that it can provide'differentiated services among different traffic categories with individual QoS requirements. In this article, we first give an overview of the key aspects of WiMAX and describe multimedia broadcast multicast service (MBMS) architecture of the 3GPP. Then, we propose a multicast and broadcast service (MBS) architecture for WiMAX that is based on MBMS. Moreover, we enhance the MBS architecture for mobile WiMAX to overcome the shortcoming of limited video broadcast performance over the baseline MBS model. We also give examples to demonstrate that the proposed architecture can support better mobility and offer higher power efficiency

Evaluation of a novel sponge-submerged membrane bioreactor (SSMBR) for sustainable water reclamation

A novel sponge-submerged membrane bioreactor (SSMBR) to treat a high strength wastewater for water reclamation was developed in this study. The performance of this system was evaluated using two kinds of polyester-urethane sponges (coarse sponge with higher density S28-30/45R and fine sponge with lower density S16-18/80R) with sponge volume fraction of 10% and bioreactor MLSS of 10 g/L. The results indicated the addition of sponge in SMBR could increase sustainable flux (2 times for S28-30/45R and 1.4 times for S16-18/80R) and lower TMP development, thus significantly reduce membrane fouling. S28-30/45R gave rise in attached growth biomass and the removal efficiencies of DOC, COD and PO4-P whilst S16-18/80R had better performance in removing NH4-N. Although the SSMBR performed well for most of the trials, the superior recycled water quality was achieved when adding S28-30/45R and S16-18/80R together in SMBR with the ratio of 2:1 and without any pH adjustment during the operation. © 2007 Elsevier Ltd. All rights reserved

Membrane fouling control and enhanced phosphorus removal in an aerated submerged membrane bioreactor using modified green bioflocculant

This study aims at developing a modified green bioflocculant (GBF) for membrane fouling control and enhanced phosphorus removal in a conventional aerated submerged membrane bioreactor (SMBR) to treat a high strength domestic wastewater (primary sewage treated effluent) for reuse. The GBF was evaluated based on long-term operation of a lab-scale SMBR. These results showed that SMBR system could achieve nearly zero membrane fouling at a very low dose of GBF addition (500 mg/day) with less backwash frequency (2 times/day with 2-min duration). The transmembrane pressure only increased by 2.5 kPa after 70 days of operation. The SMBR could also remove more than 95% and 99.5% dissolved organic carbon and total phosphorus, respectively. From the respiration tests, it was evident that GBF not only had no negative impact on biomass but also led to high oxygen uptake rate (OUR) (>30 mg O2/L h) and stable specific oxygen uptake rate (SOUR). These results also indicated that GBF had no effect on nitrogen removal and nitrification process. © 2009 Elsevier Ltd. All rights reserved

A critical review on the end uses of recycled water

Recycled water provides a viable opportunity to supplement water supplies as well as alleviate environmental loads. The authors examine the sources of recycled water and discusses various end uses. They focus on reviewing the historical development and current status of recycled water on a global scale with containing the evolvement of wastewater treatment technologies, water quality guidelines, and public attitudes. The authors also illustrate typical case studies of recycled water in a number of countries and regions, including Australia, Asia, the United States, Latin America, Europe, the Middle East, and Africa. These pilot studies can be good examples for the future projects. They identify the good prospects of further expansion and exploration of current and new end uses while emphasizing the integrated water planning and management as well as challenging and tasks in the future. © 2013 Copyright Taylor and Francis Group, LLC

Pilot scale study on a new membrane bioreactor hybrid system in municipal wastewater treatment

A pilot scale membrane bioreactor hybrid system (MBR-HS) was evaluated for municipal wastewater treatment. This novel system comprised of a granular activated carbon-sponge fluidized bed bioreactor (GACS-FBBR) followed by a submerge membrane bioreactor (MBR) with the capacity of 2L/min. The results indicated that the MBR-HS could effectively remove 90% DOC and 95% NH4-N. PO4-P removal efficiency was remained stable at about 70% throughout the experiment. Specific oxygen uptake rate (SOUR) of activated sludge increased from 0.72 to 2.21mg O2/gVSSh for the first 10days and then followed by a steady stage until the end of experiment. Sludge volume index (SVI) was always below 50mL/g, demonstrated an excellent settling properties of sludge. The system also showed an achievement in terms of low trans-membrane pressure (TMP) development rate. The TMP increasing rate was only 0.65kPa/day, suggesting GACS-FBBR can be a promising pre-treatment for MBR. © 2013 Elsevier Ltd

Risk control in recycled water schemes

Recycled water is becoming one of the indispensable and reliable water resources at present. When it is introduced as an alternative source, risks on human health and the environment become major constraints driving the application and extension of recycled water. The authors examine the sources and associated risks of recycled water and introduce the practical risk control technologies on various end uses. They also review some existing risk assessment models by comparing their strengths and weaknesses toward the good approach of integrated modeling. Some critical suggestions on risk management and communication are made based on the given information. © 2013 Taylor and Francis Group, LLC

A mini review on renewable sources for biofuel

Rapid growth in both global energy demand and carbon dioxide emissions associated with the use of fossil fuels has driven the search for alternative sources which are renewable and have a lower environmental impact. This paper reviews the availability and bioenergy potentials of the current biomass feedstocks. These include (i) food crops such as sugarcane, corn and vegetable oils, classified as the first generation feedstocks, and (ii) lignocellulosic biomass derived from agricultural and forestry residues and municipal waste, as second generation feedstocks. The environmental and socioeconomic limitations of the first generation feedstocks have placed greater emphasis on the lignocellulosic biomass, of which the conversion technologies still faces major constraints to full commercial deployment. Key technical challenges and opportunities of the lignocellulosic biomass-to-bioenergy production are discussed in comparison with the first generation technologies. The potential of the emerging third generation biofuel from algal biomass is also reviewed. © 2014 Elsevier Ltd

A novel sponge-submerged membrane bioreactor (SSMBR) for wastewater treatment and reuse

Membrane fouling has been regarded as one of the biggest challenges to widespread application of membrane bioreactor (MBR). This study focuses on minimizing the membrane fouling and improving the performance of submerged membrane bioreactor (SMBR) by porous sponge addition. The effects of sponge addition on sustainable flux and membrane fouling were investigated. Acclimatized sponge could significantly increase the suspended growth in SMBR with biomass of 16.7g/L(sponge). With the sponge volume fraction of 10%, SSMBR could enhance sustainable flux up to 50L/m2h compared with sustainable flux of SMBR (only 25L/m2h). SSMBR also exhibited excellent results in terms of DOC removal (over 95%), COD removal (over 97%), lower transmembrane pressure development, and oxygen uptake rate. Over 89% of NH4-N and 98% of PO4-P were removed when SSMBR was operated with a MLSS concentration of 15g/L

Cohomology for infinitesimal unipotent algebraic and quantum groups

In this paper we study the structure of cohomology spaces for the Frobenius kernels of unipotent and parabolic algebraic group schemes and of their quantum analogs. Given a simple algebraic group $G$, a parabolic subgroup $P_J$, and its unipotent radical $U_J$, we determine the ring structure of the cohomology ring $H^\bullet((U_J)_1,k)$. We also obtain new results on computing $H^\bullet((P_J)_1,L(\lambda))$ as an $L_J$-module where $L(\lambda)$ is a simple $G$-module with high weight $\lambda$ in the closure of the bottom $p$-alcove. Finally, we provide generalizations of all our results to the quantum situation.Comment: 18 pages. Some proofs streamlined over previous version. Additional details added to some proofs in Section