Search

The cement industry is one of the most difficult sectors to decarbonize. The manufacturing of Portland cement – the most common type of cement used for structural concrete – presently accounts for roughly 2% of global energy usage and 8% of CO 2 emissions. The current manufacturing process has not changed substantially over the past 140 years and requires temperatures above 1450 °C with heat provided by the combustion of fossil fuels. The massive CO2 emission originates from: 1) fossil fuel combustion needed to heat the raw materials ultimately to ~1450 °C for calcination and sintering, and 2) decomposition of CaCO3 in the kiln. About 1 ton of CO2 is released for every ton of Portland cement produced in this manner. To date, most of the efforts to reduce CO2 emissions have focused on the use of supplementary cementitious materials. Other approach such as capturing CO2 from fossil fuel power plants and sequestering the carbon in building materials or geologically stable substances requires the building of vast infrastructure and remains to be proven. Future manufacturing approaches that can decarbonize cement and cement-based materials are needed.This dissertation study establishes a new paradigm to decarbonize cement and cementitious materials through integrating novel manufacturing with cement chemistry and micromechanics. The new paradigm enables the novel design, manufacturing and validation of cement and cementitious materials with much reduced material-production-stage CO2 as well as life-cycle CO2 : (1) cement produced based on a clean electrochemical path instead of conventional fossil fuel combustion process; (2) ductile ultra-low-binder-content cementitious materials to reduce lifecycle CO2 by 65% and energy consumption by 70% of transportation infrastructure; and (3) an alternative low-temperature low-CO 2 “cement” clinker with additional CO2 sequestration functionality, which can be synthesized at room temperature and has potential of 4 times of CO2 uptak

Background: Drought is a major abiotic stress affecting global wheat (Triticum aestivum L.) production. Exploration of drought-tolerant genes is essential for the genetic improvement of drought tolerance in wheat. Previous studies have shown that some histone encoding genes are involved in plant drought tolerance. However, whether the H2B family genes are involved in drought stress response remains unclear. Methods: Here, we identified a wheat histone H2B family gene, TaH2B-7D, which was significantly up-regulated under drought stress conditions. Virus-induced gene silencing (VIGS) technology was used to further verify the function of TaH2B-7D in wheat drought tolerance. The phenotypic and physiological changes were examined in the TaH2B-7D knock-down plants. Results: In the TaH2B-7D knock-down plants, relative electrolyte leakage rate and malonaldehyde (MDA) content significantly increased, while relative water content (RWC) and proline content significantly decreased compared with those in the non-knocked-down plants under drought stress conditions. TaH2B-7D knock-down plants exhibited severe sagging, wilting and dwarf phenotypes under drought stress conditions, but not in the non-knocked-down plants, suggesting that the former were more sensitive to drought stress. Conclusion: These results indicate that TaH2B-7D potentially plays a vital role in conferring drought tolerance in wheat.

Cloud radio access network (CRAN) has been proposed as a potential energy saving architecture and a scalable solution to increase the capacity and performance of radio networks. The original CRAN decouples the digital unit (DU) from radio unit (RU) and centralizes the DUs. However, stringent delay and bandwidth constraints are incurred by fronthaul in CRAN, i.e. the network segment connecting RUs and DUs. In this study, we propose a modified CRAN architecture, namely hybrid cloud RAN (H-CRAN), where a DU's functionalities can be virtualized and split at several conceivable points. Each split option results in two-level deployment of the processing functions, i.e., central cloud level and edge cloud level, connected by a transport layer called "midhaul". We study the interplay of energy efficiency and midhaul bandwidth consumption when baseband functions are centralized at the edge cloud vs central cloud. We jointly minimize the power and midhaul bandwidth consumption in H-CRAN, while satisfying the network constraints. The addressed problem with the associated constrains are modeled as a mixed integer constraint optimization problem. Numerical results show the compromise between energy and bandwidth consumption, with the optimal placement of baseband processing functions in H-CRAN architecture., QC 20170803

Cloud radio access network (CRAN) has been proposed as a potential energy saving architecture and a scalable solution to increase the capacity and performance of radio networks. The original CRAN decouples the digital unit (DU) from radio unit (RU) and centralizes the DUs. However, stringent delay and bandwidth constraints are incurred by fronthaul in CRAN, i.e. the network segment connecting RUs and DUs. In this study, we propose a modified CRAN architecture, namely hybrid cloud RAN (H-CRAN), where a DU's functionalities can be virtualized and split at several conceivable points. Each split option results in two-level deployment of the processing functions, i.e., central cloud level and edge cloud level, connected by a transport layer called "midhaul". We study the interplay of energy efficiency and midhaul bandwidth consumption when baseband functions are centralized at the edge cloud vs central cloud. We jointly minimize the power and midhaul bandwidth consumption in H-CRAN, while satisfying the network constraints. The addressed problem with the associated constrains are modeled as a mixed integer constraint optimization problem. Numerical results show the compromise between energy and bandwidth consumption, with the optimal placement of baseband processing functions in H-CRAN architecture., QC 20170803

Cloud radio access network (CRAN) has been proposed as a potential energy saving architecture and a scalable solution to increase the capacity and performance of radio networks. The original CRAN decouples the digital unit (DU) from radio unit (RU) and centralizes the DUs. However, stringent delay and bandwidth constraints are incurred by fronthaul in CRAN, i.e. the network segment connecting RUs and DUs. In this study, we propose a modified CRAN architecture, namely hybrid cloud RAN (H-CRAN), where a DU's functionalities can be virtualized and split at several conceivable points. Each split option results in two-level deployment of the processing functions, i.e., central cloud level and edge cloud level, connected by a transport layer called "midhaul". We study the interplay of energy efficiency and midhaul bandwidth consumption when baseband functions are centralized at the edge cloud vs central cloud. We jointly minimize the power and midhaul bandwidth consumption in H-CRAN, while satisfying the network constraints. The addressed problem with the associated constrains are modeled as a mixed integer constraint optimization problem. Numerical results show the compromise between energy and bandwidth consumption, with the optimal placement of baseband processing functions in H-CRAN architecture., QC 20170803

Cloud radio access network (CRAN) has been proposed as a potential energy saving architecture and a scalable solution to increase the capacity and performance of radio networks. The original CRAN decouples the digital unit (DU) from radio unit (RU) and centralizes the DUs. However, stringent delay and bandwidth constraints are incurred by fronthaul in CRAN, i.e. the network segment connecting RUs and DUs. In this study, we propose a modified CRAN architecture, namely hybrid cloud RAN (H-CRAN), where a DU's functionalities can be virtualized and split at several conceivable points. Each split option results in two-level deployment of the processing functions, i.e., central cloud level and edge cloud level, connected by a transport layer called "midhaul". We study the interplay of energy efficiency and midhaul bandwidth consumption when baseband functions are centralized at the edge cloud vs central cloud. We jointly minimize the power and midhaul bandwidth consumption in H-CRAN, while satisfying the network constraints. The addressed problem with the associated constrains are modeled as a mixed integer constraint optimization problem. Numerical results show the compromise between energy and bandwidth consumption, with the optimal placement of baseband processing functions in H-CRAN architecture., QC 20170803

Cloud radio access network (CRAN) has been proposed as a potential energy saving architecture and a scalable solution to increase the capacity and performance of radio networks. The original CRAN decouples the digital unit (DU) from radio unit (RU) and centralizes the DUs. However, stringent delay and bandwidth constraints are incurred by fronthaul in CRAN, i.e. the network segment connecting RUs and DUs. In this study, we propose a modified CRAN architecture, namely hybrid cloud RAN (H-CRAN), where a DU's functionalities can be virtualized and split at several conceivable points. Each split option results in two-level deployment of the processing functions, i.e., central cloud level and edge cloud level, connected by a transport layer called "midhaul". We study the interplay of energy efficiency and midhaul bandwidth consumption when baseband functions are centralized at the edge cloud vs central cloud. We jointly minimize the power and midhaul bandwidth consumption in H-CRAN, while satisfying the network constraints. The addressed problem with the associated constrains are modeled as a mixed integer constraint optimization problem. Numerical results show the compromise between energy and bandwidth consumption, with the optimal placement of baseband processing functions in H-CRAN architecture., QC 20170803

Passive intermodulation (PIM) is a problematic type of nonlinear distortion en- countered in many communication systems. To analyze the PIM distortion resulting from ma- terial nonlinearity, a 2D PIM simulation method based on COMSOL is proposed in this paper. As an example, a rectangular waveguide ¯lled with nonlinear dielectric was taken. Both of the e®ect of nonlinear coe±cients and geometrical discontinuities were taken into consideration. The contribution of this paper is to make the PIM simulation more convenient, especially for those who are not good at analytical methods, and those who are not familiar with computational techniques. This type of analysis will aid in the development of PIM prediction, as well as PIM mitigation in the future.

Passive intermodulation (PIM) is a problematic type of nonlinear distortion en- countered in many communication systems. To analyze the PIM distortion resulting from ma- terial nonlinearity, a 2D PIM simulation method based on COMSOL is proposed in this paper. As an example, a rectangular waveguide ¯lled with nonlinear dielectric was taken. Both of the e®ect of nonlinear coe±cients and geometrical discontinuities were taken into consideration. The contribution of this paper is to make the PIM simulation more convenient, especially for those who are not good at analytical methods, and those who are not familiar with computational techniques. This type of analysis will aid in the development of PIM prediction, as well as PIM mitigation in the future.