The ecological forestry construction and development of Ningxia status and problems of analysis and discussion to the development of the forestry production and construction to provide some reference suggestions.

The degradation of reinforced concrete structures due to chloride penetration has a significant influence on structural durability. In this study, an experiment is conducted to investigate the effects of the aggregate type, mixing method, and admixture type on the chloride penetration resistance of concrete. Based on the experimental results, it is found that, since more pores and microcracks are included in recycled aggregates, the chloride penetration resistance of recycled aggregate concrete is larger than that of natural aggregate concrete. Slag is more efficient than fly ash in increasing the chloride penetration resistance of recycled aggregate concrete. It is also found that the mixing method has a significant influence on the chloride penetration resistance of recycled aggregate concrete. These conclusions can provide theoretical evidence for the design optimization of recycled aggregate concrete properties.

The study on the penetration of chloride ions into concrete is very important for the durability assessment and design of reinforced concrete structures. A cyclic wetting and drying test is conducted to evaluate the effects of concrete mix proportions on the penetration of chloride ions. Based on the experimental results, the variations in chloride ion content at various points in concrete with the water/cement ratio, maximum aggregate diameter, aggregate gradation, fly ash content, and anticorrosion agent content are analyzed quantitatively. It is found that the water/cement ratio, aggregate gradation, maximum aggregate diameter, and fly ash all have a larger influence on the penetration of chloride ions. These conclusions can provide theoretical evidence for the design optimization of concrete properties.

A three-phase composite circle-lattice modeling method was presented for predicting the chloride diffusivity of concrete.Based on the stereological analysis of aggregate distribution,an analytical algorithm for the interfacial transition zone(ITZ) area fraction was given.By applying the principle of energy equivalence,an analytical relationship of chloride diffusivity between the beam element and continuum body was derived.By modeling concrete as a three-phase composite circle,the stiffness matrix of each beam element was determined and the chloride diffusivity of concrete was calculated with the aid of the lattice modeling method.After the validity of the proposed numerical method in this paper was verified with experimental results,the effects of the maximum aggregate diameter,chloride diffusivity of ITZ,aggregate gradation and ITZ thickness were evaluated in a quantitative manner.

With the merits such as hiding receiving, easy-deploying and high security, passive location has attracted more and more attention and plays an important role in fields as diverse as navigation, location, and tracking, etc. However, the current filters models for passive location methods are most under the framework of the probability theory, thus they can not estimate the state in some passive location with fuzzy uncertainty accurately. Although the fuzzy extended Kalman filter (FEKF) can deal with the fuzzy uncertainty, it unavoidably introduces truncation error. In this paper, based on the FEKF and the iterated extended Kalman filter (IEKF) principle, a new fuzzy passive location model is built, and moreover, an iterated fuzzy extended Kalman filter (IFEKF) is proposed for estimating the target state. Compared to the FEKF and the IEKF, the proposed algorithm can not only reduce the truncation error, but also deal with fuzzy uncertainty. Moreover, it is proved that the IFEKF update is an application of the Gauss–Newton method. Then, a fuzzy passive location algorithm is proposed. Simulation results demonstrate that the proposed approach has better estimation precision than the traditional fuzzy extended Kalman filter.

How to prolong the service life of steel reinforced concrete structures located in a chloride-laden environment has become a main objective of the durability design of concrete.The influence of mix proportions,admixtures,and surface coating on the chloride diffusivity of concrete is evaluated by the AC impedance method.Based on the experimental results,the variation characteristics of the AC resistance of concrete with the water to cement ratio,maximum aggregate diameter,aggregate gradation,fly ash dosage,anti-corrosion product,and surface coating are analyzed in a quantitative manner and the corresponding explanations are given.It is found that the water to cement ratio,aggregate gradation,fly ash,and surface coating have a larger influence on the AC resistance.These conclusions can provide theoretical evidence for the durability design of steel reinforced concrete structures.

The failure modes of concrete covers were analyzed by use of the micro-plane theory.The basic formulae of the micro-plane theory were summarized.By combining the micro-plane theory with the finite element method,the whole cracking process of the concrete covers under corrosion expansive pressure was discussed.A comparison between the present results and the experimental data from literatures verified the validity of the proposed numerical method.In addition,the influences of the diameter and spacing of reinforcing steel bars and the thickness of covers on the failure modes of the concrete covers were evaluated.

Owing to their importance to the assessment of reinforced concrete structures, it is of great practical significance to predict the elastic moduli of concrete with interfacial cracks. The intention of this paper is to present an analytical solution for the elastic moduli of cracked concrete. According to the theory of stereology, the 2D scalar crack density is expressed as an explicit function of the aggregate area fraction and the central angle of interfacial cracks. For uniformly oriented and mutually interacted interfacial cracks, the effective medium method is used to derive the relative elastic moduli of cracked concrete. Based on the numerical results, it is found that the relative elastic moduli decrease with the increase of the aggregate area fraction and/or the central angle of interfacial cracks. It is also found that the relative elastic moduli are independent of the minimum aggregate diameter, the maximum aggregate diameter, and the aggregate gradation.

The fuzzy extended Kalman filter (FEKF) for state estimation can be used to deal with fuzzy uncertainty effectively. However, the linearisation processing of the FEKF introduces truncation error, which degrades the estimation precision. In order to reduce the error, a new iterated fuzzy extended Kalman filter (IFEKF), based on the FEKF and the maximum a posteriori estimation, is proposed in this article. Compared with the FEKF, the proposed algorithm can be used not only to deal with the fuzzy uncertainty, but also to reduce the truncation error and to estimate the states more accurately. With an algebraic example and a passive location simulation, it is shown that the IFEKF has better estimation precision than that of the FEKF.

With the rapid development of highly centralized city,urban landscape takes a new look and feature and urban streets are the city's framework,linking the various functional areas of the city.Green plantation design for urban street is the heart of the city streets.This paper analyzed the status and problems of streetscape in the northern cities.A few principles and suggestions were proposed for the decision maker in the landscape green.

Reading is the process of cognition comparing with monitoring. Cognitive reading and meta-cognitive monitoring, together, are functioning the reading and promoting its effects in the process. It is of great significance that training of the comprehension monitoring ability can promote English reading effects and reading comprehension ability. The theories of meta-cognition will be adopted and used in this thesis to interprete the connotations and essences of the monitoring in reading. On the base of this, suggestions will be put forward for the training of comprehension monitoring ability in English reading.

对泾源县特色林木种苗产业发展的现状做了详尽的阐述,对存在的问题进行分析,并对种苗产业今后的发展提出了具体可行的对策.对于促进泾源县特色林未种苗产业的持续发展具有一定的指导参考意义.

Based on biological characters of hawkthorn,experiments on its introduction into Jinyuan were carried out under difference condition.Successful experiences and measures were summarized for follow-up actions.

A finite element method is presented for predicting chloride diffusion coefficient in concrete.First,concrete is considered as a three-phase composite material consisting of aggregate,interfacial transition zone(ITZ) and cement paste.By comparing two typical unit cell models the advantage of the circular unit cell model in simulating concrete is demonstrated.Since the ITZ thickness is much smaller than the aggregate size,the advancing front method is adopted to divide the unit cell as accurately as possible.The finite element method is then used to obtain the numerical solution for the chloride diffusion coefficient in concrete.Finally,the validity of the method developed is verified by comparing the numerical results with the experimental data.Based on the numerical results,the effects of maximum aggregate diameter,chloride diffusion coefficient of ITZ,ITZ thickness and aggregate gradation on the chloride diffusion coefficient in concrete are evaluated in a quantitative manner.

Cables in a special section must cut across The Grand Canal in China,especially the construction site is located in the downtown area with relatively poor geological and environmental conditions.In order to be navigable for The Grand Canal in China during the period of construction,the technology of non excavating to cut across The Grand Canal in China was used. The article laid stress on introducing a technology that used small-sized machinery to drag curve pipelines cutting across The Grand Canal in China,key works in the construction organization,and the exploration of the technology improvement.The technology was first to be applied in Zhejiang province,which is extremely difficult to construct in seabeach.The experiences and lessons of this construction are useful reference to other similar projects.

六盘山位于宁夏固原市南部,是我国工黄土高原具有代表性的天然次生林区,素有"黄土高原明珠"之称,其天然林对周边地区涵养水源,调节气候,改善生态环境之功效是巨大的华山松是六盘山林区主要天然次生乔木树种之一,目前,六盘山区的天然华山松针阔混交林约0.2万hm2,华山松纯林接近0.13万hm2.

根据现场原位勘测试验及常规室内土工试验结果 ,按不同土类建立土的初始剪切模量G0 （或剪切波在土中传播速度Vs）与土的孔隙比e的回归表达式 ,以及G0 与土层标准贯入值N和土层深度H的回归表达式。用所得回归表达式可以按不同土类通过常规土工试验确定土的初始剪切模量G0 并用于土层地震反应分析。