Temperature control of buildings by adobe wall design

The adobe house developed in the hot arid climate of the American Southwest has the virtue of being cool in the day and warm in the night. The adobe wall acts as a filter giving nearly a 12-hr phase lag in the outside temperature oscillation. However, on reaching the inside, the oscillation suffers a strong attenuation in amplitude. In a previous paper it was shown that if the resistivity of the wall could be varied in a certain way from outside to inside, thenthe attenuation would be considerably reduced. In this paper a formula is given for the minimum possible attenuation under given design restrictions. Then it is shown how to make an optimum wall by suitably proportioning two or three layers of different materials. Numerical illustrations are given.     

High temperature ferroelastic phase in LiKSO4 crystals

Optical studies of LiKSO₄ crystals were performed in polarized 11yh.t within the temperature range from 300 up to 1000 K. The observations confirmed the existence of two phase transitions at about 700 and 940 K respectively. The high-temperature phase between 700 and 940 K was found to be ferroelastic.     

How to avoid logarithms in comparisons with uniform random variables

In many algorithms for sampling from non-uniform distributions the logarithm of a uniform deviate must be compared with some test quantity. It is shown that all these comparisons can be done efficiently without calling a logarithm subprogram: two procedures for this task are presented and compared.     

Pollution-prevention analysis and the quenching of steels

With the goal of improving process efficiency and reducing risk, this article describes a pollution-prevention analysis technique that can be applied to most secondary steel heat-treating operations involving quenching. Costs, risk assessments, and pollution-prevention options are discussed, as are the effects of quenching on two subsequent processes—parts cleaning and tempering. In contrast to many process comparisons, the issues of worker exposure, material safety and toxicity, liability, waste reduction, reclamation, and disposal are emphasized.     

Photostability of polyetherurethaneureas

Polyetherurethaneureas (PEUUs) were synthesised from polyethylene-glycols (PEGs) of molecular weight 400, 600 and 1000, 4,4′-diphenylmethanediisocyanate (MDI) and aliphatic diamine chain extenders, 1,3-propanediamine (PDA) and 1,6-hexanediamine (HDA). Polymer films were irradiated with 365 nm light at 293 K and the effects of polyether soft segment length and urea hard segment on photo-oxidative stability were studied by following the variation in weight-average molecular weight (M _w), gel formation and stress-strain properties. Changes in ultraviolet and infrared spectroscopy were monitored on photo-oxidation and hydroperoxide content determined. The soft segment length was increased by increasing the molecular weight of PEG from 400 to 1000 and hard segment structure was changed by variation of diamine. It was noted that the structure of urea and polyether soft segment length plays an important role in photostability of PEUUs. PDA chain extended PEUUs were more stable than HDA chain extended PEUUs.     

Electron traps created in gate oxides by Fowler–Nordheim injections

Two types of electron traps, donor-like and acceptor-like, are created in the gate oxide of metal-oxide-semiconductor capacitors by Fowler–Nordheim electron injections. Electrical properties (areal density, capture cross-section, centroid) of each type of trap are determined by using the avalanche electron injection method and by combining capacitance–voltage and current–voltage measurements. These properties are measured with regard to the Fowler–Nordheim fluence up to breakdown and for both injection modes (electrons injected either from the gate or from the substrate of capacitors).