Optimization of Land Use Structure Based on Ecological GREEN Equivalent

Optimization of land use structure consists of economic and social and ecological optimization.Applying the minds of system engineering and principles of ecology,this paper presents such thoughts:the optimal forest_coverage rate calculated according to the reality of a district is set as main standard of ecological rationality in the district;through considering the value of ecosystem services of the land with GREEN equivalent (mainly cultivated land and grassland)and based on the rule,GREEN equivalent,this paper introduces the area conversion between woodland and cultivated land,also between woodland and grassland;this paper establishes a multi_dimension controlling model of optimization of land use structure.In addition,a multi_objective linear programming model for optimization of land use structure is designed.In the end,this paper tests and verifies this theory of ecological optimization,taking Qionghai city in Hainan Province as an example.

Land Use Structure in Wuhai City on Basis of Ecological Green Equivalence

The paper took Wuhai District as an example, bases on the contrast be-tween the land use condition in 2005 and 2010, and applied the ecological green equivalence to establish a mathematic model of ecological optimization of land use structure, to establish the ecology green equivalent mathematical model and survey the value of region green equivalent, and then assess the ecological environment situation. The results show that the ecological environment has been deteriorated in Wuhai from 2005 to 2010, so the ecological environment was poor. In order to in-crease eco-efficiency of land use, garden, urban green space and woodland area should be raised in the optimization program.

The Factor Decomposition on Carbon Emission of China——Based on LMDI Decomposition Technology

Carbon emission is the current hot issue of global concern. How to assess various contributing factors for carbon emission is of great importance to find out the key factors and promote carbon emission reduction. In this paper, the author constructs an identical equation for carbon emission, based on the economic aggregate, the economic structure, the efficiency of energy utilization, the structure of energy consumption, and the coefficient of carbon emission; by applying to LMDI decomposition technology, the author analyzes the carbon emission of China from 1995 to 2007 at industrial level and regional level. The results show that the expansion of economic aggregate is the main reason for China' s rapidly increasing carbon emission and the increase of energy utilization efficiency is the key factor that can hold back the increase of carbon emission. In addition, the change of industrial structure or regional structure and the change of traditional energy structure have limited influence on the carbon emission, and their potentials have not yet been exploited. At the end of this paper, the author proposes the efforts that China should make to reduce carbon emission.

Adaptive Spectr um Decision Method for Heterogeneous Cognitive Radio Networks

To improve spectrum utilization and minimize interference to Primary User (PU), an adaptive spectrum decision method is proposed for Secondary User (SU), while taking traffic load balancing and spectrum heterogeneity into consideration. Long-term statistics and current sensing results are integrated into the proposed decision method of spectrum access. Two decision methods, namely probability based and sensing based, are presented, compared and followed by performance analysis in terms of delay. For probability based spectrum decision, Short-Time-Job-First (STJF) priority queuing discipline is employed to minimize average residual time and theoretical conclusion is derived in a novel way. For sensing based decision we treat the interrupted service of SU as newly incoming and re-decision process is initialized to find available spectrum in a First-Available-First-Access (FAFA) fashion. Effect of sensing error in PHY layer is also analyzed in terms of extended average residual time. Simulation results show that, for relatively low arriving rate of SU traffic, the proposed spectrum decision method yields at least a delay reduction of 39.5% compared with non-adaptive method. The proposed spectrum decision can significantly improve delay performance even facing sensing errors, which cause performance degeneration to both PU and SU.

Nordic Steel Bridges--Trends and Development

The development of steel bridges has been very strong for many years implementing composite structures, higher steel grades and hybrid girders, thus improving cost efficiency in bridge superstructures. As construction moves more towards inner city, there is need for even more improvement. As global resources as scarce, and society in general expect more value for same money. With Constructional Excellence--a well defined process from steel mill to installed bridge which includes design management, new foundation solutions, the best practice of current steel bridges and intelligent installation put together in robust system solutions. This paper will show resource efficiency in three dimensions, money, time and less traffic disturbance.

Service Model Transformation of the Standards Library in the Network Environment

In the network environment, changes of resources structure, information technology and users requirements of standards library cause series of problems such as unobvious effect of services, low efficiency of resource utilization, poor innovation ability, etc. And we point out the problems and challenges faced by traditional standards library in the network environment. The standards library must redesign the organization structure and business process radically so that standards library could improve the service model, enhance the service quality and utilization rate of various document resources.

多构型组合式模块化可展开天线机构设计与分析

针对空间可展开天线大口径、高收纳率、高结构利用率等迫切发展需求,提出一种多构型组合式模块化可展开天线机构。首先,阐述了机构的总体方案,分别从模块组合规则、肋单元展收原理等对结构进行了详细分析,并基于机构学基本理论对机构的自由度进行了计算;其次,根据机器人学理论分别建立了单模块与多模块的运动学模型,利用空间等包络圆法求解出各肋单元夹角间的关系;同时采用数值仿真软件对多模块联动过程中肋单元夹角的变化规律进行了研究,对建立的多构型组合式模块化机构运动学模型进行了验证及分析;最后对比了单构型与多构型组合式两类天线的结构利用率、收纳率等关键参数,并研制了一台六棱柱单模块原理样机,开展了展开功能试验与验证。仿真及试验结果表明:所提出的机构能够实现由收拢至展开态的运动变化,展开过程中机构无干涉、卡滞等问题;同时,提出的新构型方案不仅保留了模块化结构通用性好、易拓展等特点,还具有较高的收纳率和结构利用率,研究成果对于丰富和发展宇航空间机构基础理论,推动该型天线的工程应用等具有较高的参考价值和借鉴意义。

Triblock copolymer-assisted construction of 20 nm-sized ytterbium-doped TiO_2 hollow nanostructures for enhanced solar energy utilization efficiency

Rare-earth doped titania single-crystalline hollow nanoparticles of 20 nm are constructed via a simple sol-gel process. Amphiphilic ABA tri-block copolymers played a key role in assisting the formation of hollow structure, for which a hollow nanostructure growth mechanism is proposed. By introducing rare earth into the synthesis process, the as-prepared nanoparticles exhibit near-infrared light absorption properties. Photo-decomposition efficiency of Orange II azo dye can be successfully evaluated when using Yb3+-doped Ti O2 hollow nanoparticles as photocatalysts; it is more than two times higher than the pure Ti O2 hollow nanoparticles. The hollow nanostructured Yb3+-doped Ti O2 samples are exploited as photoanodes in N719- sensitized solar cells and prove able to improve the photoelectric conversion efficiency by measuring the solar cell parameters of dye-sensitized solar cells(DSSCs) under simulative sunlight.

Emerging dual-atomic-site catalysts for electrocatalytic CO_(2)reduction

The electrochemical CO_(2)reduction reaction(CO_(2)RR)to yield high-value added fuels and chemicals provides a promising approach towards global carbon neutrality.Constant endeavors have been devoted to the exploration of high-efficiency catalyst with rapid reaction kinetics,low energy input,and high selectivity.In addition to the maximum metal atomic utilization and unique catalytic performance of single-atom catalyst(SAC),dual-atomic-site catalysts(DASCs)offer more sophisticated and tunable atomic structure through the modulations of another adjacent metal atom,which can bring new opportunities for CO_(2)RR as a deeper extension of SACs and have recently aroused surging interest.In this review,we highlight the recent advances on DASCs for enhancing CO_(2)RR.First,the classification,synthesis,and identification of DASCs are provided according to the geometric structure and electronic configuration of dual-atomic active sites.Then,the catalytic applications of DASCs in CO_(2)RR are categorized based on marriage-type,hetero-nuclear,and homo-nuclear dual-atomic sites.Particularly,the structure-activity relationship of DASCs in CO_(2)RR is elaborately summarized through systematically analyzing the reaction pathways and the atom structures.Finally,the opportunities and challenges are proposed for inspiring the design of future DASCs with high structural accuracy and high CO_(2)RR activity and selectivity.

Temperature-controlled fabrication of Co-Fe-based nanoframes for efficient oxygen evolution

Transition metal phosphides(TMPs)have emerged as promising electrocatalysts to enhance the slow kinetic process of oxygen evolution reaction(OER).Framelike hollow nanostructures(nanoframes,NFs)provide the open structure with more accessible active sites and sufficient channels into the interior volume.Here,we report the fabrication of bimetallic Co-Fe phosphide NFs(Co-Fe-P NFs)via an intriguing temperature-controlled strategy for the preparation of precursors followed by phosphidation.The precursors,Co-Fe Prussian blue analogues(Co-Fe PBAs)are prepared by a precipitation method with Co^(2+)and[Fe(CN)_(6)]^(3−),which experience a structural conversion from nanocubes to NFs by increasing the aging temperature from 5 to 35℃.The experimental results indicate that this conversion is attributable to the preferentially epitaxial growth on the edges and corners of nanocubes,triggered by intramolecular electron transfer at an elevated aging temperature.The as-prepared Co-Fe-P NFs catalyst shows remarkable catalytic activity toward OER with a low overpotential of 276 mV to obtain a current density of 10 mA cm^(−2),which is superior to the reference samples(Co-Fe-P nanocubes)and most of the recently reported TMPs-based electrocatalysts.The synthetic strategy can be extended to fabricate Co-Fe dichalcogenide NFs,thereby holding a great promise for the broad applications in energy storage and conversion systems.

EFFECT OF TOXIC METAL ON THE STRUCTURAL DRY WEIGHT OF A PLANT： A MODEL

A two compartment mathematical model for the individual plant growth under the stress of toxic metal is studied. In the model it is assumed that the uptake of toxic metal by the plant is through root compartment. The toxic metal present in the soil interfere with the uptake and distribution of essential nutrients in plant causing decrease in the nutri- ent uptake eventually damaging the root structure. In the model it is further assumed that the resistance to nutrient transport from root to shoot compartment increases and nutrient use efficiency decreases due to the presence of toxic metal. In order to visualize the effect of toxic metal on plant growth, we have studied two models, that is, model for plant growth with no toxic effect and model for plant growth with toxic effect. From the analysis of the models the criteria for plant growth with and without toxic effects are derived. The numerical simulation is done using Matlab to support the analytical results.