Stability analysis of simply-supported rectangular plates under non-uniform uniaxial compression using rigorous and approximate plane stress solutions

The non-classical problem of buckling of a simply-supported rectangular plate due to various types of non-uniform compressive edge loads is analysed here. For each case, the elasticity solution for the internal in-plane stress field is obtained rigorously using a superposition of Airy's stress functions and also approximately using extended Kantorovich method. Subsequently, the convergent buckling loads are obtained using Galerkin's method. Results are presented to highlight the dependence of the total buckling load and the corresponding buckled shape on the edge load distribution, as well as to illustrate the applicability of the approximate plane stress solutions.     

Method of Determining Strength and Deformation Characteristics of Soils from Results of Deep Impression of Rod Plates

The possibility of determining strength and deformation characteristics of soils under field conditions using rod plates is discussed. The mutual relationship between these characteristics is established from results of deep impression of these rods.     

Chloroaromatic formation in incineration processes

The high-temperature reactions of chlorinated hydrocarbons are reviewed with a primary focus on the gas-phase molecular growth chemistry and elementary reaction mechanisms leading to the formation of chlorinated benzenes and chlorinated polycyclic aromatic hydrocarbons. Recent heterogeneous mechanistic studies of the chlorination and condensation of aliphatic hydrocarbons at lower temperatures are also summarized. Copper(II) valent species play an important role as catalyst and reagent. The main thermal pathways for chlorinated dibenzodioxins and furans have been deduced by these laboratory experiments, which try to model the complex reality of the post-incineration zone of municipal and hazardous waste incinerators.     

Procedure for predicting settlements of thawing bases for engineering calculations

It was shown that in order to compute the settlement of thawing cohesive soil under a load in time it is necessary to experimentally determine the consolidation coefficient. A procedure is suggested for determining this coefficient, as well as use of the classical solution of a differential equation for seepage consolidation to describe the settlement of soil, thawing of which can occur according to any law.State All-Union Scientific Research Institute of Roads. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 5–7, July–August, 1993.     

A steady-state model for the rotating biological disc reactor

A steady-state model for substrate removal in a rotating biological disc reactor is presented. The model considers the consumption of substrate by micro-organisms in the biofilm attached to the rotating disc, and mass transfer from the attached liquid film to the biofilm. A mass balance on substrate over the liquid in the trough provides an expression for effluent substrate in terms of the microbial kinetic constants, the geometry of the system and the operating conditions. In order to simplify the solution of the equations in the model, first order kinetics are assumed for the rate of microbial growth and substrate utilization. This simplified model can be solved, for example, by using a programmable calculator. The model predicts that the fractional removal of substrate per stage is strongly dependent on the hydraulic loading rate per unit disc area but independent of feed substrate concentration. It predicts constant removal independent of disc size provided the hydraulic loading per unit area is kept constant. The rotational speed has only a slight predicted effect on the rate of substrate removal. The predictions of the model are compared with published data from the literature for both domestic wastewater and some industrial wastes. Trends observed in the field are predicted qualitatively by the model.     

Use of toxicity test results and confrontation of some toxicity test methods with fire scenarios

The enormous, world wide research activity in the field of combustion toxicology has given rise to an impressive amount of toxicity data.

The first part of this paper discusses the problems which arise when such results are used to rank materials in an order of the relative toxicity of their combustion products or in attempting to relate them to toxicological hazard evaluation.

In the second part, after introducing the notion of fire scenarios and describing two such possible situations, existing test methods are compared in relation to their relevance to the scenario parameters. It is shown that none of the evaluated methods completely fulfills the considered conditions.

It is concluded by the authors that agreement on thoroughly described scenarios is necessary for further trials towards international harmonisation and development of test methods.     

Indirect check of aggregate pore effects on concrete

It is very difficult to quantify aggregate pores directly in a way that allows pore/water interaction to be accurately related to hardened concrete properties. This work examines, a number of aggregates through water absorption checks and gives results of tests on some concretes made with them. Three especially relevant concrete properties are examined, initial surface absorption, freeze/thaw behaviour and drying shrinkage; it is shown that aggregate absorption is reflected in these properties.     

Circular footings resting on geotextile-reinforced sand bed

The note pertains to an experimental study made on circular footings resting on semi-infinite layer of sand reinforced with geotextiles. Using the concept of homogenization of such soils, both analytical and numerical analyses have also been conducted to predict the load-settlement behavior and compared with experimental observations. The study highlights the effect of the footing size, number of reinforcing layers, reinforcement placement pattern and bond length and the relative density of the soil on the load-settlement characteristics of the footings.     

Effect of chlorination practice on soluble organics

As the practice of chlorination for the disinfection of waste effluents is apparently to be extended, this study was initiated to examine the possibility that chlorinated organics could be formed in the disinfection process. A group of pure compounds that had been demonstrated to be susceptible to chlorination were examined under conditions likely to apply under normal disinfection practice.From the results obtained, it appears only organics with ring structures and electron activating substituents, or amino groupings are capable of chlorination. The frequent presence of ammonia or amino groups means that chloramine formation with its asociated toxicity is likely. However, the presence of ammonia or amino groups will retard the reaction with other compounds making chlorination of these unlikely.     

Conceptual aspects of water re-use

A simplified model of a municipal water recycle system is presented and gives a clear picture of the relationship between process variables such as the intensity of the treatment, the accumulation of pollutants and the number of times the water is re-used. The model can be used to determine the necessary requirements for the treatment process in order to reach a certain desired drinking water quality. This model is extended to cover a variety of practical conditions. It is also shown that accumulation under practical conditions is limited, even if there is no treatment. The model predicts that the recycle system can utilise a low quality supplementary supply, e.g. brackish water. Although the model is derived for a recycle system for domestic water supply it can be used for any closed loop water system.