China's Greenhouse Gas emissions’ dynamic effects in the process of its urbanization: A perspective from shocks decomposition under long-term constraints

AbstractThis paper is about to quantify the effect of China's urbanization on greenhouse gas (GHG) emissions by separating the part driven by the economic growth from the whole effect. In order to be accurate to estimate unknown parameters, this paper follows the method of Blanchard & Quah (1989), in which identifying conditions are set by assuming some shocks have no long-term effect on corresponding explained variables. We conclude that 1) Urbanization shock has an inverted hump-shaped effect on GHG emissions, in other words, nowadays the process of China's urbanization has been accompanied with saving energy and reducing emissions; 2) The growth rate of GHG emissions, owning to the GDP shock, can be raised by almost 1.53% annually and the urbanization level approximately contributes to 18% of the change of CO2 emissions based on empirical results; 3) China's emission reductions, in the short run, are actualy in expense of decreasing economic growth and delaying the p rocess of its urbanization

Experimental and Numerical Studies of Slurry-Based Coextrusion Deposition of Continuous Carbon Fiber Micro-Batteries to Additively Manufacture 3D Structural Battery Composites

Carbon Fiber Structural Battery Composites Have Recently Attracted Growing Interests Due to their Potentials of Simultaneously Carrying Mechanical Loads and Storing Electrical Energy for Lightweight Application. in This Study, We Present a Slurry-Based Coextrusion Deposition Method to Additively Manufacture 3D Structural Battery Composites from Carbon Fiber Micro-Batteries. Cathode Slurry is Coextruded Together with Solid Polymer Electrolyte-Coated Carbon Fibers in a Single Deposition. a Network of Carbon Fiber Micro-Batteries is Achieved within the Fabricated Structural Battery Composites. Electrochemical Tests Show a Stable Charge-Discharge Performance Up to 100 Cycles. the Rheological Behavior of the Cathode Slurry is Found to Govern the Coextrusion Process and the Obtained Electrochemical-Mechanical Properties. the Rheological Measurements Are First Used to Identify Printability Windows in Terms of Solid Loadings and Binder Contents in the Cathode Slurry. Increasing Binder Contents Improve the Mechanical Properties, with Maximum 1.1 GPa and 124 GPa Obtained for Tensile Strength and Modulus, Respectively, But Lowers the Obtained Electrochemical Performance. Lowering Solid Loadings Improves Printability, Simultaneously Increasing Electrochemical Capacity (By 106%) and Tensile Modulus (By 108%) and Strength (By 40%). Further Microstructural Characterization Shows that Residual Voids Play a Major Role in the Obtained Electrochemical and Mechanical Properties. a Meso-Scale Computational Fluid Dynamics Simulation is Used to Understand Void Formation during the Coextrusion Process. the Cathode Slurry Rheology Mainly Affects Degree of Impregnation. the Findings Help Understand the Effects of the Cathode Slurry on 3D Printing and How to Further Improve Multifunctional Performance for Electrically Powered Structural Systems Where Lightweight Materials Are in Strong Demands

Direct 3D Printing of Silica Doped Transparent Magnesium Aluminate Spinel Ceramics

Transparent magnesium aluminate spinel ceramics were additively manufactured via a laser direct deposition method in this study. With a minimum porosity of 0.3% achieved, highly transparent spinel samples with the highest total optical transmittance of 82% at a wavelength of 632.8 nm, were obtained by a 3D printing approach. However, cracking was found to be a major issue affecting printed spinel samples. To control prevalent cracking, the effect of silica dopants was investigated. Increased silica dopants reduced average total crack length by up to 79% and average crack density by up to 71%. However, a high dopant level limited optical transmission, attributed to increased porosity and formation of secondary phase. Further investigation found that with decreased average fracture toughness, from 2.4 MPa·m1/2 to 1.9 MPa·m1/2, the obvious reduction in crack formation after doping was related to decreased grain size and introduction of softer secondary phase during deposition. The study demonstrated the feasibility of the proposed laser direct deposition method in directly fabricating transparent spinel ceramics while dopants showed potentials in addressing cracking issues

Effects of Zirconia Doping on Additively Manufactured Alumina Ceramics by Laser Direct Deposition

The ability to additively manufacture functional alumina ceramics has the potential to lower manufacturing costs and development time for complex components. In this study, the doping effects of zirconia on laser direct deposited alumina ceramics were investigated. The microstructure of the printed samples was analyzed in terms of grain size and composition distribution. The addition of zirconia was found to accumulate along alumina grain boundaries and resulted in significant grain refinement. The zirconia doping largely reduced crack formation during processing compared to that of pure alumina samples. In the case of 10 wt% zirconia, cracking during deposition was nearly completely eliminated, but meanwhile porosity was increased. Through grain refinement and crack reduction in 10 wt% zirconia samples, bending strength was shown to increase by nearly four times the value obtained with pure alumina. Fracture toughness was also shown to increase by 1.5 times with addition of 5 wt% zirconia, which was attributed to the crack interaction with zirconia doped grain boundary and stress induced tetragonal to monoclinic transformation of zirconia. These findings indicated the potentials of dopants during laser direct deposition of ceramics and can further be used to tailor the properties of additively manufactured ceramic components

A conserved but plant-specific CDK-mediated regulation of DNA replication protein A2 in the precise control of stomatal terminal division

The R2R3-MYB transcription factor FOUR LIPS (FLP) controls the stomatal terminal division through transcriptional repression of the cell cycle genes CYCLIN-DEPENDENT KINASE (CDK) B1s (CDKB1s), CDKA; 1, and CYCLIN A2s (CYCA2s). We mutagenized the weak mutant allele flp-1 seeds with ethylmethane sulfonate and screened out a flp-1 suppressor 1 (fsp1) that suppressed the flp-1 stomatal cluster phenotype. FSP1 encodes RPA2a subunit of Replication Protein A (RPA) complexes that play important roles in DNA replication, recombination, and repair. Here, we show that FSP1/RPA2a functions together with CDKB1s and CYCA2s in restricting stomatal precursor proliferation, ensuring the stomatal terminal division and maintaining a normal guard-cell size and DNA content. Furthermore, we provide direct evidence for the existence of an evolutionarily conserved, but plant-specific, CDK-mediated RPA regulatory pathway. Serine-11 and Serine-21 at the N terminus of RPA2a are CDK phosphorylation target residues. The expression of the phosphorylation-mimic variant RPA2a(S11,21/D) partially complemented the defective cell division and DNA damage hypersensitivity in cdkb1;1 1;2 mutants. Thus, our study provides a mechanistic understanding of the CDK-mediated phosphorylation of RPA in the precise control of cell cycle and DNA repair in plants

Continuous Occupancy Mapping in Dynamic Environments Using Particles

Particle-based dynamic occupancy maps were proposed in recent years to model the obstacles in dynamic environments. Current particle-based maps describe the occupancy status in discrete grid form and suffer from the grid size problem, wherein a large grid size is unfavorable for motion planning, while a small grid size lowers efficiency and causes gaps and inconsistencies. To tackle this problem, this paper generalizes the particle-based map into continuous space and builds an efficient 3D egocentric local map. A dual-structure subspace division paradigm, composed of a voxel subspace division and a novel pyramid-like subspace division, is proposed to propagate particles and update the map efficiently with the consideration of occlusions. The occupancy status of an arbitrary point in the map space can then be estimated with the particles' weights. To further enhance the performance of simultaneously modeling static and dynamic obstacles and minimize noise, an initial velocity estimation approach and a mixture model are utilized. Experimental results show that our map can effectively and efficiently model both dynamic obstacles and static obstacles. Compared to the state-of-the-art grid-form particle-based map, our map enables continuous occupancy estimation and substantially improves the performance in different resolutions.Comment: This paper has been accepted by IEEE Transactions on Robotic

SRIBO: An Efficient and Resilient Single-Range and Inertia Based Odometry for Flying Robots

Positioning with one inertial measurement unit and one ranging sensor is commonly thought to be feasible only when trajectories are in certain patterns ensuring observability. For this reason, to pursue observable patterns, it is required either exciting the trajectory or searching key nodes in a long interval, which is commonly highly nonlinear and may also lack resilience. Therefore, such a positioning approach is still not widely accepted in real-world applications. To address this issue, this work first investigates the dissipative nature of flying robots considering aerial drag effects and re-formulates the corresponding positioning problem, which guarantees observability almost surely. On this basis, a dimension-reduced wriggling estimator is proposed accordingly. This estimator slides the estimation horizon in a stepping manner, and output matrices can be approximately evaluated based on the historical estimation sequence. The computational complexity is then further reduced via a dimension-reduction approach using polynomial fittings. In this way, the states of robots can be estimated via linear programming in a sufficiently long interval, and the degree of observability is thereby further enhanced because an adequate redundancy of measurements is available for each estimation. Subsequently, the estimator's convergence and numerical stability are proven theoretically. Finally, both indoor and outdoor experiments verify that the proposed estimator can achieve decimeter-level precision at hundreds of hertz per second, and it is resilient to sensors' failures. Hopefully, this study can provide a new practical approach for self-localization as well as relative positioning of cooperative agents with low-cost and lightweight sensors