James B. Taylor

Characterization of surface roughness effects on pressure drop in single-phase flow in minichannels

Roughness features on the walls of a channel wall affect the pressure drop of a fluid flowing through that channel. This roughness effect can be described by (i) flow area constriction and (ii) increase in the wall shear stress. Replotting the Moody’s friction factor chart with the constricted flow diameter results in a simplified plot and yields a single asymptotic value of friction factor for relative roughness values of e∕D>0.03 in the fully developed turbulent region. After reviewing the literature, three new roughness parameters are proposed (maximum profile peak height Rp, mean spacing of profile irregularities RSm, and floor distance to mean line Fp). Three additional parameters are presented to consider the localized hydraulic diameter variation (maximum, minimum, and average) in future work. The roughness e is then defined as Rp+Fp. This definition yields the same value of roughness as obtained from the sand-grain roughness [H. Darcy, Recherches Experimentales Relatives au Mouvement de L’Eau dans...

Ergonomic interventions for the furniture manufacturing industry. Part II -- Handtools

Abstract The objectives of this intervention research project were to develop and evaluate engineering controls for the reduction of the upper extremity injury risk in workers in the furniture manufacturing industry. The analysis of OSHA Form 200 logs and surveys of furniture workers revealed that upholsterers, workers who use random orbital sanders and workers who use spray guns are at higher levels of risk of illness than the rest of the working population. An on-site ergonomic analysis of these three jobs was performed and the following risk factors were identified for each of these three work groups: upholsterers—repetitive, high-force pinch grips; sanders—long-duration static grip forces; and sprayers—awkward postures (ulnar wrist deviations and wrist flexion). Engineering interventions in the form of new or modified handtools were then evaluated in the laboratory to assess their effectiveness in reducing exposure to these risk factors. For sanding, an interface was created that secured the hand to the sander with the intention of reducing the need for static grip forces during sanding. A new handtool was created for upholsterers that replaced the repetitive pinch grips with a power grip. Finally, a commercially available spray gun with ergonomic features was evaluated. Each of these modified tools/methods was compared with the standard methods typically used in industry. The results show that most of the intended beneficial effects were realized. The random orbital sander interface reduced extensor muscle activities by an average of 30%. The upholstery handtool reduced the intrinsic hand muscle activities by an average of 51%. The effects of the adapted spray gun were most prominent when working on horizontal surfaces and showed an average reduction of 40° of wrist flexion and 14° of ulnar deviation as compared to the standard pistol grip spray gun in this activity. Relevance to industry The ergonomic intervention research described in this report documents a reduction in exposure to risk factors for upper extremity cumulative trauma disorders for three work activities in the furniture manufacturing industry.

Contoured edge slice generation in rapid prototyping via 5-axis machining

Abstract Rapid prototyping, though a relatively new discipline, has proven to be a valuable tool in the reduction of the time and cost associated with developing new products. The value of rapid prototyping shows the promise of increasing even further as it matures and offers higher quality parts, in less time, and for lower costs. Improvements in these areas are all addressed in current rapid prototyping research in various ways. This paper presents a method for greatly improving the geometric accuracy, and thus the overall quality, of rapid prototype parts by making use of 5-axis machining. An algorithm is presented to generate the contoured edge slices for the rapid prototype parts in several levels of complexity. A simple algorithm is presented to generate a single edge contour for each section of the slice, and a more complex algorithm is also presented to allow for the 5-axis machining of “sub-layers” within a slice. It will be shown that sub-layer 5-axis machining provides the possibility to produce the most accurate rapid prototype parts on the market today. The benefits and limitations of the process will be enumerated and summarized. An inexpensive design for the implementation of a 5-axis machine configuration for a proposed sheet-based rapid prototyping process will be presented. A novel characteristic of the proposed process is that it does not require that the sheets be produced independently and post-assembled via a registration system. The process allows for the parts to be built up on a platen as the layers are cut, thus removing the need for a registration system and eliminating post-assembly errors. Sample parts and algorithm verification will also be presented.

A kinetic study on the effect of coupling distance between insoluble trypsin and its carrier matrix

Abstract Trypsin (EC 3.4.4.4) was covalently attached by its carboxyl groups through peptide chains of various length to an insoluble polystyrene matrix. The peptide chains ranged from one to ten amino acid residues in length composed entirely of glycine residues, except for a terminal alanine bound to the polystyrene matrix in chains of two to ten residues. Using tosyl- l -arginine methyl ester as substrate, the observed catalytic rate, k cat , is independent of the chain length or column flow rate. However, the apparent Michaelis constant is dependent upon both parameters. These results suggest that the contributions from “unreactive” molecules and electrostatic interactions are negligible for this case. The data are discussed in terms of effects of the unstirred layer and the microenvironment of the surface.

Ergonomic interventions for the furniture manufacturing industry. Part I -- Lift assist devices

Abstract The objectives of this intervention research project were to develop and evaluate engineering controls for the reduction of low back injury risk in workers in the furniture manufacturing industry. An analysis of injury/illness records and survey data identified upholsterers and workers in the machine room as two occupations within the industry at elevated risk for low back injury. A detailed ergonomic evaluation of the activities performed by these workers was then performed and the high risk subtasks were identified. The analysis for upholsterers revealed: (1) high forces during the loading and unloading of the furniture to and from the upholstery bucks, (2) static awkward postures ( extreme flexion>50° , lateral bending>20° , twisting>20°) during the upholstering of the furniture, and (3) repetitive bending and twisting throughout the operation. For machine room workers, this ergonomic evaluation revealed repetitive bending and twisting (up to 5 lifts/min and sagittal flexion>80°, lateral bending>15°, twisting>45°) when getting wooden components from or moving them to the shop carts that are used to transport these materials. Engineering interventions were then developed and evaluated in the laboratory to document the reduction of exposure to these stressors. The height-adjustable upholstery buck system eliminated the lifting and lowering requirements and affected trunk kinematics during the upholstery operation by reducing peak sagittal angles by up to 79% (average: 52%; range: 27–79%), peak sagittal accelerations by up to 42% (average: 71%; range: 0–74%) and peak lateral position by up to 31% (average: 20%; range: 12–31%), and showed no impact on time to complete the task. The machine room lift reduced peak sagittal angle by up to 90% (average: 76%; range: 64–90%), peak sagittal accelerations by up to 86% (average: 72%; range: 59–86%) and had a positive impact on the time to complete the task (average reduction: 19%). Relevance to industry The ergonomic intervention research documented in this report shows the impact of engineering controls for the furniture manufacturing industry on the risk factors for work-related low back injuries.

A process for solvent welded rapid prototype tooling

Abstract Rapid prototyping is widely seen as an effective tool for compressing time to market for new products. The typical process followed by industrial and mechanical design groups is to model a new product in a CAD system, rapidly prototype the component parts, use the parts as patterns for RTV silicone molds, and then cast polyurethane prototype parts from the molds. These prototype components are an integral part of the simultaneous engineering process. With prototype components, engineers are able to design, implement, test, and refine the assembly systems for a product while production tooling for the components is being made. In this paper, we describe an experimental rapid prototyping process, known as solvent welding freeform fabrication (SWIFT), that is very well suited to the production of short to medium run tooling. The advantage of the process is that it is very fast and inexpensive relative to the traditional RTV silicone mold making process. The process also produces ABS or polystyrene molds which last considerably longer than RTV silicone molds. Process development details are provided in the paper and its application to a power tool component is described.

THE SIX FACETS MODEL: TECHNOLOGY MANAGEMENT IN THE EFFECTIVE IMPLEMENTATION OF CHANGE

Organizational fitness is often achieved by making changes in business operations. These changes frequently involve the use of a new technology. The effective implementation of change is aided by examining the benefits and challenges of technology management when making decisions. Important elements for consideration in technology management are technology evaluation, integration, planning, implementation, training and change. A solution is proposed to combine and encompass these elements of technology management to encourage the positive aspects and avoid the negative aspects of change implementation. The tool consists of principles to be addressed for each element.

Precision X-Y microstagee with maneuverable kinematic coupling mechanism

Within modern manufacturing, there is a growing need for micropositioning units with very fine resolution and high repeatability. In this paper, a new micropositioning system based on the kinematic coupling is developed, and its unique path control is derived. The results show that such a system can provide the user with the ability to exploit the inherent position repeatability of the kinematic coupling, while maintaining full two-dimensional (2-D) motion control. More importantly, this mechanism is shown to have a mechanical amplification (leverage) that can allow for a significant increase in the effective positioning resolution of the position sensors employed by the actuators driving the kinematic coupling mechanism. This may drastically reduce the cost for achieving ultrahigh positioning resolution demanded by industry without using complicated and extremely expensive actuators and position sensors.

The Preparation of Microenvironments for Bound Enzymes by Solid Phase Peptide Synthesis

It has become evident that in the area of immobilized enzymes no single attachment system or resin support or reactor design will be optimum for all enzymes. Thus it is imperative that we develop a repertoire in these areas to allow for system designs which will either optimize the immobilized enzyme or make it more substrate selective. We sought to develop a systematic method that would allow one to specify the chemical microenvironment on the support resin onto which the enzyme is attached; thereby enabling a more systematic investigation of the influence of surface environment on enzyme structure and activity. Hornby et al., (1) Goldstein et al., (2), and Goldstein (3) have shown that the surface characteristics of the resin, i.e., its charge and hydrophobic nature, do influence the apparent kinetic parameters of immobilized enzymes. Furthermore, we (4) have shown that the spatial placement of the enzyme from the resin’s surface also affects the kinetic parameters. This led us to examine the feasibility of synthesizing peptide chains of a given chemical characteristic on the surface of a resin and attaching the enzyme to these chains. Such a method would allow comparisons of microenvironments without the interferring effects of matrix structure or enzyme distance from the surface, since these could be held constant.

Characterization of the Effect of Surface Roughness and Texture on Fluid Flow: Past, Present, and Future (Keynote)

That surface roughness has an effect on fluid flow in networks has been understood for well over a century. The exact effect roughness has on fluid flow has not been completely understood, but a working estimate has been offered by a variety of authors over time. The work of Colebrook, Nikuradse, and Moody has provided practitioners with a method to include at least a first order estimate of roughness effects, but their work has been limited to relative roughness to diameter values of 5% or less. Modern fluidic systems at the mini and micro levels routinely violate the 5% relative roughness threshold due to the inability to control the roughness of surfaces to sufficient levels with respect to decreasing system scale. Current work by Kandlikar, et al., has extended the traditional methods of assessing surface roughness effects up to 14% relative roughness by including the effect of constricted flow diameters and modifying the Moody diagram to reflect new experimental data. The future of micro fluidics would suggest that trends for miniaturization will continue and that further understanding and experimentation will be warranted. This is especially true with regards to understanding the role of roughness on the flow in mini and micro channels.Copyright