Stock Items Research Articles

Allocating for Acceptable Risk Instead of Expected Value

Allocation of inventory, spares, or redundancy in reliable systems often seeks to maximize expected orders filled or hours until failure (assuming known distributions). Often there is no opportunity for an averaging process to permit this expectation to materialize. Each operation of the system may be critical, instead of the average of many, or the first shortage may terminate the whole operation. Predictable adequacy of each operation is attained by considering the full distribution, e.g., of operating hours before failure, instead of just the mean (expected) value. Distributions with small standard deviations permit more precise prediction of probable time before failure (shortage). Plans based on marginal utility concepts tend to avoid the expected-value trap but do not necessarily minimize the appropriate risk of shortage. Operating characteristic curves, like those used in quality control, allow intelligent consideration of the risks involved in choosing among alternate allocation plans. Allocation of a small number of stock items is used to illustrate the criterion.

A sand drier for a concrete laboratory with an Appendix on thermal performance

Summary This article describes a rotary sand drier made of stock items of equipment to serve the requirements of a laboratory at Canterbury University College, Christchurch, New Zealand, in which all concrete for experimental and demonstration purposes is made with dry aggregate conforming to pre-determined grading curves. From 15 to 20 tons of aggregate are used each year.

Building Our Future with Books

If anyone doubts the power that books have over the affairs of man let him notice two events of prime importance in the history of our civilization. Less than one hundred years ago three books destined to change much of the thinking of the world appeared in Europe and America. A few years ago Hitler held a book burning in the attempt to destroy the books of those he does not like. Darwin's Origin of Species was published after the author had concluded from exhaustive studies that animal life proceeded from a lower form in a progressive manner until all life may be considered as an evolutionary process. Not only was the course of the sciences altered but man's pattern of thinking was changed. Two great camps arose around men like Wallace, Haeckel, and Huxley who defended and explained Darwin's ideas and around the churchmen who attacked any idea which did not give credence to the doctrine of divine origin. This fight took on major proportions in the social sciences where Spencer based his system of sociology and ethics on the evolutionary process. In the twentieth century the famous trial at Dalton, Tennessee riveted the attention of the world on this fight. In spite of its adversaries the theory of evolution is here, to stay. Man's thinking has been enriched by the concept. At the time when the liberal forces of the United States were fighting to free the Negro from slavery Karl Marx was slowly building his socialistic doctrines which were destined to change the course of man's economic thinking. Unlike Darwin's book, Das Kapital has never been understood by many students. But ideas from the book have found expression in the rapidly growing labor unions of the world. Systems of government have been based upon Marx's theories. The country whose government is based on Marx's principles, Russia, is now one of the leading defenders of the democratic way of life. If any event may be said to have precipitated the Civil War in the United States it was the appearance of Harriet Beecher Stowe's Uncle Tom's Cabin. Around it the forces for emancipation collected and gave vent to their emotional out-bursts. With John Brown as the embodiment of the brave martyr who died for the right Uncle Tom's Cabin became the story which abolitionists used to convert the faltering and teach the ignorant. This book was not only the first best seller in the United States but remains one of the most profitable items in the bookseller's stock. These three books had an enormous influence upon the course of human history. But books per se, are not powerful. They are the vehicles of ideas which are the tools of man's thinking. So powerful are the ideas expressed in books that the arch-dictator of all time took it as one of his first tasks to destroy books. There have been book burnings before Hitler. The church has attempted to

Editorial

In most business enterprises there comes once a year what is known as inventory time. It is a time for checking up all the items of stock on the shelves in order to arrive at the current capital investment. Sometimes the turnover has been so rapid that there is left nothing of what was on the shelves a year earlier. At other times there will be found much that should have moved out during the year. In the latter case the common procedure is to stage a special sale in order to clear the shelves. Often the condition is anticipated by a pre-inventory sale.How many of us have attempted to apply the inventory idea to our teaching, research, and extension work? Of course we respond with varying degrees of promptness to the annual request from the business office for a check of the physical inventory—but what about an .