Volume Of Experimental Work Research Articles

Peridynamic modelling of clay erosion

Experimental observations of the erosion of clays indicate a high degree of coupling between the hydro-chemical processes in the clay–water system and the mechanics of erosion. In contrast with the volume of experimental work and the significance of swelling clay erosion in many geotechnical engineering problems, limited advances have been made with the predictive modelling of this phenomenon. The critical erosion step, missing in existing models, is the particles’ detachment from the moving boundary of the expanding clay – a discontinuous process. This paper presents, for the first time, a non-local formulation for clay erosion, which brings together clay swelling, particle detachment and detached particle transport, into a single modelling tool. The detachment criterion, an essential element of the integrated erosion model, is first tested against a series of experimental benchmarks to show the excellent agreement between calculated and experimental results. The integrated erosion model is subsequently validated by comparison with experimental data for the behaviour of compacted bentonite under several eroding environments. The results: (a) show clearly the capacity of the model to capture concurrently the free swelling of clay, the detachment of clay particles and the transport of detached particles in the eroding environment; and (b) support strongly the applicability of the model to account for the hydro-chemical conditions (composition and velocity) of the eroding environment. The proposed multi-physics non-local formulation, successfully validated for hydro-chemical effects on clay erosion, provides a robust framework for incorporating a wide set of additional couplings.

Methodology of 3D simulation of processes in technology of diamond-composite materials

In the present paper, the problem of increased effectiveness in manufacturing when using diamond abrasive tools is addressed. For this reason, a three-dimensional (3D) methodology is proposed. The aforementioned methodology consists of several parts containing 3D simulation that covers all the basic stages of the life cycle of the tools, from the sintering of diamond composite materials, grinding, and dressing of grinding wheels, to sharpening of single point tools and machining. Furthermore, the creation of expert systems for assignment of rational characteristics of diamond wheels and grinding modes is investigated. The results of these investigations allow reducing the volume of experimental work, offering optimum grinding conditions and allowing the development of new technologies, tools, and equipment.

HIGH-SPEED VISION OF PLANTS

The challenges in machine vision specific to the food and agricultural sectors include the requirements of high speed, variable product shape, and surface inconsistency. Object identification such as plants, has not been developed to as great extent in agriculture as in other industries, due primarily to the complexity of plant images. Out of the enormous volume of experimental work that has been published during the past decade, two major problems which have not been fully resolved yet, emerge: There is a limitation of algorithms execution speed, and most of the image processing algorithms used to recognize the determinant features require very expensive hardware to execute in real-time. In addition to these obvious problems, digital image processing encounters another difficulty. In order to analyze an object, it must be presented in the input image as a single item. This is not a real situation in the field. This paper proposes a solution to these problems by using an optical system which is not only fast but also cost-effective. Optical pattern recognition (OPR) techniques work with low cost components and at the same time are fast and operate at almost the speed of light. The system is based on a real-time element for displaying images. A computer simulation has been developed to demonstrate this concept. This system would be of great benefit to automatic identification of plants. Another important aspect is the embedding of fast image processing systems as a component of quality management systems.

A mathematical model of argon-arc welding in a quadrupolar magnetic field

The results of full-scale and computer experiments in welding in a magnetic field indicate that the accuracy of the mathematical model of weld formation is sufficient for engineering practice. The development of the mathematical model of welding in a magnetic field makes it possible to reduce greatly the volume of experimental work by replacing experiments by computer simulation as well as to reduce the cost of technological preparation of welding production

Cyanobacteria in New Zealand inland waters: Experimental studies

Abstract A small volume of experimental work with cyanobacteria in New Zealand has been produced through the last two decades. Except for some studies with geothermal organisms biased to New Zealand conditions, most work has followed the world‐wide trends in cyanobacterial research. There has been some emphasis on N2‐fixing species, but symbiotic relationships, metabolic kinetics, nutrient and other environmental factors promoting ecological dominance, and toxicity have been investigated.

Polymerization of Butadiene Using Ziegler-Natta Catalysts—Recent Developments

Abstract The products of Ziegler-Natta catalyzed reactions, including high density polyethylene, polypropylene, and other thermoplastics and elastomers, have become familiar to all. While an enormous volume of experimental work was completed during the 1950s and 1960s, it has only been during the 1970s that the multiplicity of mechanistic schemes developed have been subjected to scrutiny. The majority of these have been concerned with polymerization of ethylene and α-olefins and because they have been adequately reviewed recently, are discussed only briefly here. A similarly large volume of empirical experimental work has enabled commercial production of polybutadiene using stereoregular catalysts. However, the mechanisms involved are of recent development, largely due to the additional configurational complexity of products, the multicompound nature of the catalyst complex, and the susceptibility of the system to contamination. Advances which have been made during the last decade are highlighted, with pa...

Psychodynamics and psychosomatic symptoms

T HE TERM "psychosomatic" is a clinical, descriptive one which refers to the appearance of physical symptoms in relation to emotional states or mental activity. From a dynamic viewpoint it seems grossly inadequate. In the first place, it indicates little about the particular patient before us in analysis. Secondly, it tells nothing about the psycho-somatic relationship, and thirdly it lumps together, indifferently, manifestations of quite different order and dynamic process. Can we equate, for instance, signs of direct body participation in an affective state--e.g., the crying of joy, the tachycardia of rage, or the pallor of humil ia t ion--with such complex symptoms as aia hyster ica l paralysis? Or such symptom-complexes as asthma or tuberculosis with the somatic symptoms arising out of a hypochondriacal conviction of illness? In one case the somatic symptoms may be the physiological component of a healthy, affective state of simple order; in another the affect may be compulsive or irrational. Or anxiety may be involved. Generally, this is considered an affect, yet resulting from the interplay between "simpler" emotions, so that although a large volume of experimental work may give factual evidence of particular somatic changes being "produced" by particular affects, it does not help too much in understanding the patient, whose emotional states are more complex, or unconscious, or cannot be easily identified either by patient or observer. Still other somatization reactions, such as the "conversion" symptoms, may not only involve affects but conceptualideational complexes in conflict. And even more complex clinical syndromes, such as asthma or tuberculosis, have been related to personality types or "profiles" or groups of character traits. In these cases not only is the psychosomatic relationship often most strained, but the origin and nature of the psychological state is difficult to explain. Most attempts to explain these symptoms have focused on the nature or type of affective-ideational factor, and on the relationship of such particular condition to a type of somatic response. They assume an interaction between more or less definable psychic and somatic events. These theories have been well reviewed in a recent article 1 and it is unnecessary to detail them here. Suffice it to say that the degree of relatedness has been seen to vary from a close, precise specificity (affect --> symptom, personality --> syndrome) to a limited specificity (non-specific anxiety --~ symp-