Sound Engineering Practices Research Articles

Design considerations, machinery and control options in coil winding

Coil winding machine design is dictated by a coil's complexity, material tension limitations, machine versatility, automation/operator intervention, production volume, and budgetary considerations. Winding machine designs, tensioner devices, coil winding patterns, and potential coil winding problems are explored. It is suggested that coil winding is an art with foundations in sound engineering practices and experience. Computerized controls offer accuracy and versatility, but understanding the basics of machine design, tension control, and a wire's path leads the designer and customer to an intelligent and cost-effective solution to the winding application.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The role of regulations in the prevention of occupational injury

To measure the impact of safety regulations on the occurrence of occupational injury, an investigation was made of 98 worksites where severe or moderately severe injuries had recently been reported, and, where possible, of matching worksites where a similar accident had not occurred, at least for a period of 2 years. 53 of the 98 injuries were considered to be attributable to a violation of a regulation. Matching worksites were obtained for 43 of these 53 cases, and of these 30 (70 ± 14%) were found to be in compliance with the regulation violated at the corresponding accident site. On the basis of this figure it is estimated that failure of compliance with regulations would result in a 2.24-fold increase in the injury rate. Interviews with management at the complying worksites suggested that compliance was more often related to a conscious effort to comply with regulations than a fortuitous outcome of what appeared to be sound engineering practice or “common sense”. Compliance was significantly associated with management awareness of regulatory requirements, but not with possession of a copy of the relevant regulations. Compliance was significantly associated with training of management in safety, and with observance of a priori determined principles of good safety management. Of the 98 injuries investigated, 48 were considered to be amenable to regulatory control. Investigation of all non-accident worksites studied ( n = 78), yielded practical information in 25 on means of reducing the risk of the injury which had occurred at the corresponding accident site. It is concluded that regulations have a substantial relevance to occupational injury in that (i) the injury rate would be at least halved if all regulations were complied with; (ii) there was nevertheless a substantial rate of compliance with regulations, without which the rate of severe injuries may be more than doubled; (iii) substantial benefit may be gained from increasing the ambit of regulations; and (iv) management training and good management practices are most likely to prevent those injuries which are associated with violation of regulations. It is also recommended that accident investigations should include inspection of comparable worksites, not only to detect similar risk factors to those responsible for accidents, but to identify control measures developed by other companies.

EFFECTS OF HURRICANE HUGO ON AGRICULTURAL STRUCTURES

ABSTRACT A tour of damage to agricultural structures by hurricane Hugo was conducted. Empty grain bins which exhibited improper anchorage tended to fail. Post-frame buildings that were improperly anchored, braced or fastened failed, while others that were designed and constructed using sound engineering practices generally withstood hurricane winds.

Section 3: IMPLEMENTATION

A key element in the implementation of the Comprehensive Water System Plan (WSP) is proper compliance with State and local requirements governing adoption of this document. As previously discussed, this WSP must be submitted to the Washington State Department of Health (DOH) for review and approval. In addition, the State Environmental Policy Act of 1971 (SEPA), Chapter 43.21C, Revised Code of Washington (RCW), requires that a WSP must be accompanied by an appropriate environmental document. An Environmental Checklist has been prepared for the City of Sunnyside’s (City) WSP and its recommended activities. This Checklist is included as Appendix M of the WSP. Details of the WSP’s content are referenced in the Checklist. It is anticipated that both negative and positive impacts will occur to earth, water, land use, population, public services, and utilities as a result of implementing the WSP. However, this WSP has been developed to accommodate and plan for expected changes and not to dictate those changes. Therefore, scheduled implementation and sound engineering and construction practices will minimize any adverse impacts. Once the final environmental determination has been made and comments received from reviewing agencies, the WSP will be adopted by the City Council. The final environmental determination will be attached or incorporated with the WSP for submittal to DOH for approval. The final environmental determination, approved City construction specifications and details, and DOH approval will combine to endorse the WSP contents and allow the construction of distribution mains listed in the WSP, without individual approval by DOH.

Analysis and design of a traveling wave tube feedthrough

Results are presented of an investigation aimed at understanding the critical parameters that cause surface breakdown of a high-vacuum feedthrough insulator used in traveling-wave tubes (TWTs). Further impetus was the need to design a feedthrough with a higher hold-off voltage compared to existing designs so as to increase the reliability of TWT operation. Improvement in voltage hold-off was accomplished by fundamental electric field analysis and sound engineering practice. The electric stress enhancement at the insulator/flange interface was the source of flashover initiation. It was found that the hold-off voltage was greatly improved if the flange met the insulator at a right angle rather than an acute angle. The influence of various device operational parameters and physical constraints imposed by the geometry of the TWT were also investigated. A combination of spot welding and cathode termination leading to high stress enhancement led to the lowest breakdown voltages among the factors studied here. Practical means of ameliorating the premature insulator failure are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Wetland projects of the California state coastal conservancy: An assessment

Abstract Since 1978, the California State Coastal Conservancy's Enhancement Program funded 23 projects and plans affecting 2,328 wetland acres for almost $4 million. Twelve of the projects created, restored, or enhanced wetlands. These projects were evaluated with reference to their functional and perceived success. Ten of the projects were conflict‐resolution or land‐management plans. These projects were evaluated based on their specific goals. The results of this analysis concluded that the Enhancement Program projects were relatively successful. The success of the wetland creation projects was found to be a result of sound engineering practices. Unsuccessful projects generally were overly complex or lacked appropriate engineering. The success of the plans was found to be a result of the staffs innovative solutions, perseverance, and the unique powers of the Conservancy. Unsuccessful plans were typically overambitious and required intensive management by Conservancy staff.

The Use of Reliability Techniques on Traction and Rolling Stock

Traditionally British Rail has used experience and sound engineering practice to ensure reliable traction and rolling stock. In-service reliability has been measured in terms of frequency of train delays in traffic. Availability is measured in terms of the number of vehicles available for service at a fixed time each day. Service problems are reported to the design authority at periodic service problem meetings. Modern traction and rolling stock specifications call for higher petformance to be obtained within tighter cost, size and weight constraints. To meet these demanding specifications, new system designs of increasing complexity have to be adopted. This has resulted in an increased engineering risk that the performance specifications will not be met. To ensure that reliability and availability remain acceptable, it is becoming increasingly necessary to use reliability modelling and assessment techniques. These are used from initial concept, throughout the design phase, and during the operational life of the equipment. This paper outlines some of the basic techniques which are available to assist in the solution of today's service problems and the design of tomorrow's vehicles. The application of these techniques will be illustrated by examples.

Beach nourishment, a practical method of erosion control

Artificial beach nourishment, the placing of sand onto eroded beaches, is increasingly employed by coastal engineers as an alternative to structural control of shoreline erosion. Man-made beaches approximating natural forms and processes offer greater protection against storms than eroded beaches and provide increased recreational opportunities. It is hoped that maintenance nourishment will keep pace with subsidence and eustatic rise in sea level, primary causes of beach erosion. Even though negative impacts of beach restoration may be short-lived and limited in scope, sound ecological engineering practices require careful monitoring of dredging operations.

Solar Energy Utilization by Physical Methods

On the basis of the estimated contributions of these differing methods of the utilization of solar energy, their total energy delivery impact on the projected U.S. energy economy (9) can be evaluated (Fig. 5). Despite this late energy impact, the actual sales of solar energy utilization equipment will be significant at an early date. Potential sales in photovoltaic arrays alone could exceed $400 million by 1980, in order to meet the projected capacity buildup (10). Ultimately, the total energy utilization equipment industry should attain an annual sales volume of several tens of billion dollars in the United States, comparable to that of several other energy related industries. Varying amounts of technology development are required to assure the technical and economic feasibility of the different solar energy utilization methods. Several of these developments are far enough along that the paths can be analyzed from the present time to the time of demonstration of technical and economic feasibility, and from there to production and marketing readiness. After that point, a period of market introduction will follow, which will differ in duration according to the type of market addressed. It may be noted that the present rush to find relief from the current energy problem, or to be an early leader in entering a new market, can entail shortcuts in sound engineering practice, particularly in the areas of design for durability and easy maintenance, or of proper application engineering. The result can be loss of customer acceptance, as has been experienced in the past with various products, including solar water heaters. Since this could cause considerable delay in achieving the expected total energy impact, it will be important to spend adequate time at this stage for thorough development. Two other aspects are worth mentioning. The first is concerned with the economic impacts. Upon reflection on this point, one will observe that largescale solar energy utilization will not cause a greater impact than other new energy sources, based on the reasoning that a self-consistent set of conditions will have to be fulfilled in order to achieve such large-scale use. Without cost competitiveness, other energy resources would fill the requirements, or, if their resource and cost structure also would create severe problems, the economic forecasts simply cannot be fulfilled. We also should not think of a "solar-only" energy future. First, there is still enough coal to last for several hundred years. Second, there should be enough fissionable fuel available to operate breeder reactors for a similar time span, and geothermal energy could satisfy some requirements for a long time. And finally, there may be fusion. It would be unlikely that any one of the available options should play a really dominant role. Rather, we should expect to be using an energy mix, just as we do now, with each energy source supplying the requirements which it can satisfy in the most suitable way, and solar energy should play an important role in this long-range future.

Paper 6: Submerged Motor Drives for Glandless Pumps

In view of the environmental operating conditions, special techniques have to be used to permit the manufacture of the submerged type of motor as an industrial proposition. The first choice to be made is that of stator winding conductor insulation, which must be impervious to water, flexible to wind, and have good thermal stability. A thorough survey of the limited materials available for such an application determined that high density polythene, extruded on to a flexible stranded cable, would best meet these requirements. Polythene has a relatively low flow temperature, which may be increased, and the mechanical stability of the cable improved, if it is subjected to irradiation dosage. The cable and the necessary seal termination are subjected to accelerated life testing at operating conditions in static pressure vessels before commitment to production. The concept of the mechanical design calls for the use of small rotating diameters consistent with sound engineering practices. Where possible, rotating surfaces must be smoothed to minimize water turbulence losses.

The domain of the engineer

The traditions of professional engineering are outlined. Events in its early history and the recent influence of science have opposed these. A return to the concepts of the pioneers may pave the way to reclaiming the benefits offered by sound engineering practice.

Engineering and the Scientific Revolution

HARDLY MORE THAN a couple of generations ago sound engineering practice consisted for the most part of a combination of manual dexterity with a rather large number of empirical rules approved by long, evolving experience. Yet engineering had already been invaded by formulae or principles which were not merely empirically derived: thermodynamical calculations, the procedures for determining structural stresses, part at least of the theory of fluid-flow as well as the whole new development of electrical engineering were products of theoretical investigation which had been confirmed by experiments and in due course by experience. In such cases as these we may properly speak of engineering's being dependent upon science. It is true that the practical engineer of the nineteenth century derived his figures rather from tables and graphs than by going back to pure theory; what matters is the origin of the rules he applied in a theoretical analysis rather than in a codification of successful empirical practice. And it is significant that all the time the trend was away from customary rules to theoretically-derived ones; by and large the engineer did not distrust science: he welcomed it.

Some Solutions to Problems of Operating Germanium Transistor Servo Amplifiers at High Ambient Temperatures

Some solutions are outlined to the problem of using readily available types of germanium power transistor at ambient temperatures as high as 85°C, such as might be found in aircraft. Germanium transistors can be used at ambients within 5°C of their maximum storage temperatures if the power dissipated in the transistor is kept low and there is provision to handle the high <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_{c0}</tex> . Both the mean power dissipation and the peak instantaneous dissipation must be considered, and the thermal and electrical circuits designed to insure that the junctions never, even instantaneously, exceed the maximum temperatures set by the transistor manufacturers. A typical design for high-temperature operation is described, consisting of a three-stage direct-coupled amplifier to operate a standard 3-watt 400 cps servo motor. This amplifier, in which sound engineering practices are stressed, sacrifices some gain for stability, reliability, and efficiency. It is designed to tolerate wide variations in transistors and most other components with a minimum change in gain or available output. The maximum mean power dissipation is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\frac{1}{2}</tex> watt, and the maximum peak instantaneous dissipation is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1\frac{1}{2}</tex> watts. The first of these amplifiers was built two years ago, and although several have been in operation, there have been no failures. The techniques are applicable to other circuits where transistors must operate close to their maximum storage temperature.

The Development of Mariemont, Ohio

Mariemont, Ohio, a town in the making, situated just outside the city limits of Cincinnati, is a practical example of the application of the principles of community development laid down by Mr. John Nolen, M. AM. Soc. C. E., and is the result of the joint effort of men representing various professions. At Mariemont, which is patterned after the English garden cities, American methods, combined with modern city planning ideas, good architecture, and sound engineering practices, are creating a community which is unique in the history of town planning in the United States.