Thermal insulation properties of wood-based sandwich panel for use as structural insulated walls and floors

Thermal insulation and warmth-keeping properties of thick plywood-faced sandwich panels with low-density fiberboard (plywood-faced sandwich, PSW), which were developed as wood-based structural insulation materials for walls and floors, are comprehensively clarified. The properties focused on were thermal conductivity (λ), thermal resistance (R), and thermal diffusivity (D). The results for PSW panels were compared with those for commercial wood-based boards, solid wood, and commercial insulators. The λ values were measured for PSW panels and their core and face elements. As a result, the composite theory of λ was found to be appropriate for PSW composites, because the calculated/experimental λ ratios were approximately 90%. The λ values for PSW panels with densities of 340 kg/m³ (PSW350) and 410kg/m³ (PSW400) were 0.070 and 0.077W/mK, respectively. The R values for PSW350 and PSW400 were 1.4 and 1.2m²K/W, and the D values were 0.00050 and 0.00046m²/h, respectively. Consequently, the PSW provided thermal insulation properties superior to those of the boards and in terms of warmth-keeping properties were greatly advantageous over the insulators. These advantages were due to the moderate densities of PSW panels. The PSW panel with sufficient thickness showed remarkably improved thermal resistance compared with those of the boards.     

Agroforestry and portfolio theory

Portfolio theory is used to analyse the risk of hypothetical agroforestry systems. It is shown that the relationship of the returns of the components of an agroforestry system, expressed in terms of the covariance or correlation of returns, is of vital importance in correctly defining risk. Agroforestry systems can be classified as efficient or inefficient. Inefficient systems are such that an alternative system exists which has a greater return for the same level of risk. Thus, inefficient systems do not represent rational choices for agroforestry systems. Finally, the conclusion is reached that it is impossible to design a best system, but rather a set of efficient systems of differing risk and return can be defined. This set of efficient systems is referred to as the efficient frontier.     

用上限方法求解钢筋混凝土深梁极限荷载的方法

由于剪切强度问题的复杂性,对于钢筋混凝土深梁的抗剪计算的方法,各国学者提出了许多种理论,到目前尚无统一标准和规范。本文以钢筋混凝土塑性理论为基础,用上限方法确定了钢筋混凝土深梁剪切破坏时的极限荷载的计算方法。     

关于强度理论的探讨

本文主要依据弹性体在外力作用下发生变形时,各点处产生弹性应变能的概念,探讨了材料力学教科书中常用的强度理论的提法,提出了主剪应变能强度理论,这一理论除了具有概念较为确切、清晰等优点外,还可以推论到其他强度理论及材料力学的其他内容上。     

A Game Theory Model on the Information Screen Effect of Compose of Option and Probation Period Mechanism

We have put forward a theory that the probation period mechanism have an information screening function when a company is inviting applications for job, which would be a supplement for the spence model. One of the merits of the model is that it could screen the informations of employee's capacity when there are fewer differences between the capacities of employees. This paper also has proved that option mechanism has a information screening effect and the compose of option and probation period mechanism could decrease the screen cost of a company. We have derived the mathematical Principles of probation period mechanism and the compose of option and probation period mechanism design in the paper.     

Analysis on Strategies to Construct Portfolio Insurance

The strategies of portfolio insurance are introduced according to its principles and design thinking.The(authors) give the simple mathematical models and practical processes of option-based portfolio insurance(OBPI),constant mix(CM),constant proportion portfolio insurance(CPPI),and time-invariant portfolio protection(TIPP),and use risky assets containing 180 index's stocks of Shang-hai Stock Exchange and risky-free assets containing bonds to form portfolio to do empirical simulating.Based on the results,they analyze the above strategies comparatively,gives the(related) investment suggestion,and shows how to avoid risk without restriction on profit.     

Economic Analysis of Administrative Monopoly and Its Solution

Administrative monopoly in China is analyzed with microeconomics tools such as rent-seeking theory, comparative advantage theory and game theory. A rent seeking model is given to study administrative monopoly. Futhermore, the authors propose that the barriers brought by administrative monopoly not only increase consumers burden, but also make enterprises run with high cost and low efficiency, and optimal resource distribution can not be done. Administrative monopoly can not be eliminated unless administrative monopoly is regulated within anti-monopoly law and its legal liability is enhanced, which is proved with game theory. In order to solve administrative monopoly, China should construct a law system concluding anti-monopoly law and administrative law as a reinforce.     

THE REAL RESISTIVE MODEL FOR FREQUENCY -DOMAIN ANALYSIS

A new model for frequency - domain analysis - the real resistive model which is based on Complex Network Theory is proposed in this paper. The network equations formed with the new model without contain complex numbers because there are only sources and resirtive elements in the model. A CAA algorithm for frequency analysis by using the new model is also given. It is shown that the trouble with the complex operation in the traditional algorithm has been avoided. The algorithm presented in this paper is simple and convenient,hence it is easy to popularize.