Critical Biot's number for Determination of the Sensitivity of Spherical Ceramics to Thermal Shock

A critical Blot number, which determines both the sensitivity of spherical ceramics to quenching and the durations of the temperature-wave propagation and the thermal stresses in the ceramics subjected to thermal shock, is theoretically obtained. The results prove that once the Blot number of a ceramic sphere is greater than the critical number, its thermal shock failure will be such a rapid process that the failure only occurs in the initial regime of heat conduction, whereas the thermal shock failure of the ceramic sphere is uncertain in the course of heat conduction. The presented results provide a guide to the selection of the ceramics applied in the thermostructural engineering with thermal shock.     

Forecast for the Next Eon: Applied Cosmology and the Long-Term Fate of Intelligent Beings

Cosmology seems extremely remote from everyday human practice and experience. It is usually taken for granted that cosmological data cannot rationally influence our beliefs about the fate of humanity—and possible other intelligent species—except perhaps in the extremely distant future, when the issue of heat death (in an ever-expanding universe) becomes actual. Here, an attempt is made to show that it may become a practical question much sooner, if an intelligent community wishes to maximize its creative potential. We estimate, on the basis of a greatly simplified model, the rate of loss of potentially useful information due to the delay in undertaking the colonization of the largest gravitationally bound structures in an accelerating universe. In addition, we argue for a natural cosmological extension of the classical taxonomy of advanced technological communities given by Kardashev. New developments in the fields of anthropic self-selection and physical eschatology give, for the first time, solid foundations to such results. This may open some new (and possibly urgent) issues in the areas of future policy making and transhumanist studies generally. It may also give us a slightly better perspective on the SETI endeavor.     

Dynamical Critical Exponent for the Majority-Vote Model

We investigate the dynamical behavior of the isotropic majority-vote model on a square lattice using a combination of damage spreading and finite-size scaling methods. For initial damage D(0)1/2, the dynamical phase diagram exhibits a chaotic-frozen phase transition at a critical noise parameter q _c =0.0818±0.0002, while for D(0)1/2 the damage does not propagate for any value of the model's parameter 0q<1/2. From simulations at q _c , we find that the dynamical critical exponent is z=0.65±0.05.     

Mean-Field Critical Behavior for the Contact Process

The contact process is a model of spread of an infectious disease. Combining with the result of ref. 1, we prove that the critical exponents take on the mean-field values for sufficiently high dimensional nearest-neighbor models and for sufficiently spread-out models with d>4:()– _c as _c and ()( _c–)^–1 as _c, where () and () are the spread probability and the susceptibility of the infection respectively, and _c is the critical infection rate. Our results imply that the upper critical dimension for the contact process is at most 4.     

Critical indices for the charged Bose gas

A self-consistent version of the static random phase approximation leads to a quasi-particle energy satisfying ?(k)=Ak^v for small k, where v ≈ 1.8. The critical indices are those of an ideal Bose gas with this spectrum.     

Percus-Yevick equation for an inhomogeneous fluid: Critical region

The critical region of a locally nonuniform fluid with gaussian density inhomogeneity is investigated. Nonclassical behaviour is found; critical exponents agree very well with those obtained from the perturbation theory of liquids. The action of an external field shifts the critical region and weakens the critical behaviour. Discussed effects could be verified experimentally.     

Assessment of the NM-Lines Sensitivity for Measurement Errors

In this work we investigate the sensitivity of the recently proposed NM-lines technique with respect to the error in the angle measurement in comparison with the conventional M-lines technique. The obtained results show that the NM-lines technique allows us to reduce the effect of the measurement errors and thus obtain better results for a given angular resolution.     

卫星热设计参数的灵敏度分析

卫星热设计参数的灵敏度分析为卫星热设计的可靠性验证以及卫星运行可靠性提供了分析方法．利用系统灵敏度理论,对卫星热设计问题进行了分析,导出了卫星热设计系统的灵敏度方程．并以太阳能电池板的热设计为例,对系统的灵敏度方程进行了求解,分析了各参数的灵敏度,为卫星热设计中结构及物性参数的确定提供了依据。