Elementary Statistics

Fractional two-level factorial designs are often used in the early stages of an investigation to screen for important factors. Traditionally, 2 ^n-k fractional factorial designs of resolution III, IV, or V have been used for this purpose. When the investigator is able to specify the set of nonnegligible factorial effects, it is sometimes possible to obtain an orthogonal design with fewer runs than a standard textbook design by searching within a wider class of designs called parallel-flats designs. The run sizes in this class of designs do not necessarily need to be powers of 2. We discuss an algorithm for constructing orthogonal parallel-flats designs to meet user specifications. Several examples illustrate the use of the algorithm.     

Elementary water waves

New elementary farfield and nearfield time-harmonic water waves, observed from a Galilean reference frame, are given. These two related classes of waves are modifications of classical elementary plane waves that are obtained in a simple way, using only elementary fundamental considerations, by analyzing waves that slowly grow from rest at time T = −∞ and are bounded in the farfield. This approach circumvents the need for a radiation condition, which may indeed be regarded as (indirectly) satisfied ab initio by the elementary farfield and nearfield waves given here. The farfield waves are the product of classical elementary waves by a function, called radiation function, that is defined explicitly in terms of the dispersion function. Thus, this radiation function is valid not only for water waves, but more generally for a broad class of linear dispersive waves. For illustration and verification purposes, elementary stationary-phase considerations are used to determine the main properties (phase and group velocities, wave patterns, asymptote and cusp lines) of farfield waves, and two particular classes of water waves—steady ship waves and time-harmonic waves generated by an offshore structure—in uniform finite water depth are considered. The elementary nearfield waves can readily be used to construct free-surface Green functions or in a spectral representation of nearfield flows.     

简谈中国气体

回顾我国气体20多年所走的道路,通过分析同国外气体发展的差别,强调气体基础研究的重要意义,对我国特种气体由量的满足到质的飞跃充满信心.     

Elementary models for biological interaction

This paper provides a brief review of two theories of biological interaction of hazardous exposures, the Hewlett-Plackett theory and the sufficient-component cause theory. Although the former has its origin in bioassay and the latter in epidemiology, it is possible to show that the two theories are isomorphic in that they imply identical relationships between biological interaction and disease rates. The relationship of biological interaction to statistical and public health interaction is also reviewed. In particular, the presence or absence of biological interaction under the two theories does not correspond in a one-to-one fashion with the presence or absence of any proposed form of statistical or public health interaction. This observation confirms the importance of clearly distinguishing different concepts of interaction.     

浅谈真空冷冻干燥技术

经过长期从事进口真空冷冻干燥设备（VIRTIS 500SRC-18X）和ATLAS（RAY-50）的生产实践，通过学习总结了真空冷冻干燥的三个阶段，这对研究某一食品真空冷冻干燥工艺会有所帮助的。     

浅谈液化天然气系统

简介了液化天然气的生产流程、运输工具以及液化天然气站的各组成设备 ,还较详细地介绍了给液化天然气汽车加气的有关设备     

Elementary processes in nanowire growth

We propose that many of the complex morpho-logical phenomena observed during nanowire growth arise from the interplay of just three elementary processes: facet growth, droplet statics, and the introduction of new facets. We incorporate these processes into an explicit model for the vapor-liquid-solid growth of fully faceted nanowires. In numerical simulations with this model, different conditions can lead to either growth of a free-standing wire or lateral growth where the catalyst droplet crawls along the surface. An external perturbation can cause the wire to kink into a different direction. Different growth conditions can also change the shape of the growth tip. All of these phenomena have been observed, and the model behavior is consistent with the experimental observations.