寒冷地区新风机组热水盘管冻裂根源与防治方法

通过对中国计量科学研究院昌平院区工艺性空调系统新风机组热水盘管冻裂根源的分析,提出几种不同的防治方法,结合现场实际条件选出了一种最适合本系统的解决方案,以期通过本项目的成功实施能对寒冷地区类似空调系统的设计、施工和运行起到一定参考和指导作用。     

Effect of Contact Mode on the Electrical Transport and Field‐Emission Performance of Individual Boron Nanowires

Vapor–liquid–solid processing of boron nanowires (BNWs) can be carried out either using a bottom‐up or top‐down growth mode, which results in different contact modes between the nanowire and the substrate. The contact mode may strongly affect the electrical transport and field‐emission performance of the individual boron nanowires grown on a Si substrate. The electrical transport and field‐emission characteristics of individual boron nanowires of different contact modes are investigated in situ using a scanning electron microscope. The contact barriers are very distinct for the different contact modes. Moreover, the transition from a “contact‐limited” to a “bulk‐limited” field‐emission (FE) process is demonstrated in nanoemitters for the first time, and the proposed improved metal–insulator–vacuum (MIV) model may better illustrate the nonlinear behavior of the Fowler‐Nordheim (FN) plots in these nanoscale systems. Individual BNWs with different contact modes have a discrepancy in their emission stability and vacuum breakdown characteristics though they have similar aspect ratios, which suggests that their electrical transport and field‐emission performance are closely related to their contact mode. Boron nanowires grown in the base‐up mode have better field‐emission performances and are more beneficial than those grown in the top‐down mode for various device applications.     

The behavior of individual and aggregate stock prices

News about an individual stock normally has only a trivial impact on the aggregate economy. The news of the aggregate stock market, however, may have a significant impact on the prospects of the economy, and so has a large impact on the pricing kernel. This difference between the aggregate stock market and individual stocks is analyzed in a dynamic general equilibrium setting with incomplete information. The main findings are as follows. First, consistent with existing empirical evidence, the correlation between stock returns and earnings surprises is, on average, positive at the individual stock level and is lower or even negative at the aggregate level. Second, a stock’s return is less sensitive to its earnings surprises if the expected earnings growth of the stock is more pro-cyclical. Third, a decrease of information quality of a stock increases its risk premium if the stock accounts for a small fraction of the economy, but decreases its risk premium if the stock accounts for a large fraction.     

Optimal Convergence Rates of Classical Solutions for Vlasov-Poisson-Boltzmann System

The dynamics of charged dilute particles can be modeled by the two species Vlasov-Poisson-Boltzmann system when the particles interact through collisions in the self-induced electric field. By constructing the compensating function for multi-species particle system, the optimal time decay of global classical solutions to this system near a global Maxwellian is obtained through a refined energy method.     

Synthesis of water-dispersible photoluminescent silicon nanoparticles and their use in biological fluorescent imaging

Water-dispersible silicon nanoparticles (Si-NPs) are desirable for applications in biological techniques. A simplified method to synthesize such particles is reported here. The resulting Si-NPs are water-dispersible and luminescent. Under the excitation of UV light, the Si-NPs emit strong red light with a peak maximum at 606 nm and a quantum yield of 6%. They are highly stable, and remain so over several weeks. Fourier Transform Infrared (FTIR) spectroscopy shows a visible Si–CH₂ scissoring vibration mode. Furthermore, the surface chemical bondings were confirmed by X-ray photoelectron spectroscopy (XPS). In the Si2p and C1s core levels, Si–C components are observed. The diameters of the synthesized Si-NPS as measured by atomic force microscope (AFM) are approximately 5 nm. Furthermore, the nanoparticles can be taken up by cultured cells. Fluorescence images of Si-NPs within MCF-7 human breast cancer cells show they are distributed throughout the cell tissue.     

An attractor for the singularly perturbed Kirchhoff equation with supercritical nonlinearity

We consider a quasilinear wave equation of Kirchhoff type

?_utt−(1+‖∇u‖²)Δu+_ut+f(u)=g(x),$?u_{tt}-(1+{\Vert \mathrm{\nabla }u\Vert }^2)\mathrm{\Delta }u+u_t+f(u)=g(x),$

where ?>0$?>0$ is a small parameter. Without any growth restrictions on the nonlinearity f(u)$f(u)$, we prove the existence of a finite-dimensional global attractor on an appropriate (bounded) phase space. The key step is the estimate of the difference between the solutions of a quasilinear dissipative hyperbolic equation of Kirchhoff type and the corresponding quasilinear parabolic equation.     

塑化剂迁移量测定和迁移模型研究进展

综述国内外塑化剂迁移量测定和迁移模型研究进展,从创新实验测定方法和实验误差分析的角度简要评述了迁移量测定的研究成果;从数学模型的角度对微分方程模型、统计模型和计算机模拟3类重要迁移模型进行评述。最后指出,测定实验和迁移模型相结合来研究塑化剂迁移问题是未来一个值得重视的方法。     

特大容积滑冰馆的扩声

介绍一个体积约３６００００ｍ＾３左右，８０００－１００００座的特大型滑冰馆的扩声设计及竣工测量结果。