Since 1960, pallet production has quadrupled, increasing the pallet industry's use of hardwood lumber from 14 percent to almost 50 percent of total hardwood lumber production. Part of this growth can be attributed to the grocery and related products industry, which should continue as a major growth area for pallet usage over the next decade. The general objective of this study is to provide information that can be used to understand the long-term potential and long-term trends in the grocery pallet market which relate to future regional timber demands by the pallet industry. Specific objectives are: (A) Provide information on current use of grocery pallets in the grocery distribution industry; (B) Provide theoretical framework for future analysis of the regional demand for grocery pallets; and (C) Provide information on demand for regional timber resources resulting from grocery pallet production within specified regions. Models are presented representing demand and supply in the grocery and related products and grocery pallet markets. In the grocery pallet model, demand for new grocery pallets is expressed as an 'excess demand' where demand for new grocery pallets equals the difference between aggregate supply of pallets to grocery distribution and available inventory of grocery pallets in the system. Inventory of grocery pallets in grocery distribution is expressed as a function of dollar volume of retail sales, based on application of a stock adjustment model for durable inputs. Consumption of grocery pallets by the grocery distribution industry is shown to be an important part in overall new pallet production even though the pallet used, 48"x40", only constitutes about 11 percent of total new pallet production in 1986. Estimates of national consumption of new grocery pallets in 1986 are broken down into regional estimates of new pallet consumption. Volume of wood raw material used in 1986 for production of grocery pallets is estimated to exceed 838 million board foot of wood raw material, or potentially 18 percent of total hardwood raw material consumed in production of all types of pallets. National trends effecting wood use in grocery distribution are considered. Specific regional trends effecting wood raw material use are not identified. / Ph. D.

Nachwachsende Rohstoffe stellen in zunehmendem Umfang eine sinnvolle Alternative zu herkömmlichen Konstruktionswerkstoffen im Maschinen- und Anlagenbau dar. Speziell Lagenholzwerkstoffe bieten enormes Potential, den Anforderungen an Nachhaltigkeit und Ressourceneffizienz gerecht zu werden, ohne auf eine entsprechende technische Leistungsfähigkeit verzichten zu müssen. In diesem Zusammenhang wird im Vortrag ein an der Technischen Universität Chemnitz entwickeltes Konzept vorgestellt, Metallwerkstoffe (Stahl und Aluminium) im Maschinenbau durch nachwachsende Rohstoffe zu substituieren. Am Beispiel eines in der Automobilproduktion eingesetzten Fördersystems aus Holzwerkstoff wird dieses Konzept erläutert. Dabei handelt es sich um ein im Karosserierohbau bei Volkswagen verwendetes Skidfördersystem. Anhand einer Anforderungsliste wird im Vortrag schwerpunktmäßig der konstruktive Aufbau des Förderers vorgestellt, wobei vor allem die Unterschiede und Besonderheiten zur herkömmlichen Metallbauweise im Vordergrund stehen. Die Berechnung und Auslegung der Transporteinheit erforderte besondere Rechenmodelle, die für die verwendeten Insertverbindungen hergeleitet wurden und im Vortrag kurz erläutert werden. Speziell das dynamische Anforderungsprofil der Anwendung an die Struktur sowie die Verbindungstechnik ist durch bekannte Berechnungsgrundlagen (Bauwesen, Eurocode 5) nicht abgedeckt. Aus diesem Grund werden dem Maschinenbau entstammende Dauerfestigkeitsbetrachtungen speziell für Verbindungen des Ingenieurholzbaus genutzt. Zum Abschluss des Vortrages wird auf den mittlerweile eineinhalb jährigen, störungsfreien Praxiseinsatz bei der Volkswagen AG in Wolfsburg eingegangen und die Vorteile zum herkömmlichen Stahlfördersystem aufgezeigt. / Renewable resources become more and more a useful alternative to conventional construction materials in machine and plant construction. Especially wood veneer composites offer an enormous potential to meet the requirements of sustainability and resource efficiency without having to give up appropriate technical and mechanical capabilities. In this context the University of Technology in Chemnitz has developed a concept to replace metal materials such as steel or aluminum in mechanical engineering by renewable resources. A skid conveyor system made of wood veneer composites in automotive production used by Volkswagen will give a further explanation of this concept. Based on a list of requirements the lecture focuses the structural design. Especially the most notably differences and peculiarities to the conventional metal construction will be shown. The calculation and dimensioning required special calculation models, which have been derived for the used insert joints. Especially the dynamical requirement specifications of the application concerning the structure itself and the joints are not covered by computational models from civil engineering (Eurocode 5). Therefore fatigue strength examinations originated from mechanical engineering were adapted for joints usually used in timber engineering. The speech closes by summarizing the 18 month failure-free operation of totally five conveyor units at Volkswagen in Wolfsburg as well as their advantages compared to the conventional steel conveyor system.

Advanced material handling systems' impact on flexible manufacturing systems (FMS) have increased the efficiency and work rate over conventional manufacturing assemblies. The interaction of automated guided vehicles (AGVs), roller conveyors and conveyor belts with robots and machine tools forms highly sophisticated assembly operations. Whilst material handling in FMS today is conventionally used to transport assembly units from one work station to another, it does not take an active role in the manufacturing process. With manufacturers implementing more advanced manufacturing principles to perform agile manufacturing, there is a growing need to implement "smarter" material handling systems that would perform essential, integral roles in the assembly process. This research outlines the development of a cordless linear synchronous motor (CLSM) material handling system. The CLSM incorporates a permanent magnet courier that moves without tether restrictions on an integrated reverse air bearing system which eliminates friction. The CLSM provides a material handling system with enhanced travel, flexibility and accuracy. The CLSM material handling system is designed to integrate with overhead manipulators and part feeders to form a comprehensive flexible manufacturing system. This research covers the 2-D finite element modeling (FEM) used to determine the CLSM's optimal parameters. The development of the motor windings design and construction, together with the control system for the CLSM, is also covered. The CLSM novel air bearing system is outlined and compared to other conventional linear bearing systems. The possible impact of the CLSM on current manufacturing systems is explored to determine the validity of the research project and possible further research opportunities. / Thesis (M.Sc.Eng)-University of Natal, Durban, 2000.

"Back injuries have consistently been the most common types of injuries suffered by people at work. They have been a significant worker injury problem in most, if not all, industrialised countries for many years and manual handling has long been established as a significant task related back injury causal factor.[...] This research project established that the manufacturers of the jet airlines used by the airlines in this study had not previously been acquainted with the issue of baggage handler back injuries.[...] This study also canvassed the opinion of airline safety professionals and airline baggage handlers concerning baggage handling tasks and working environment related causal factors. [...] A major focus of this research project was also to measure the effect of ACE and Sliding Carpet, two commercially available retro-fit baggage systems, on the risk of back injuries to baggage handlers stacking baggage within Boeing B737 narrow-body aircraft." / Doctor of Philosophy

"Back injuries have consistently been the most common types of injuries suffered by people at work. They have been a significant worker injury problem in most, if not all, industrialised countries for many years and manual handling has long been established as a significant task related back injury causal factor.[...] This research project established that the manufacturers of the jet airlines used by the airlines in this study had not previously been acquainted with the issue of baggage handler back injuries.[...] This study also canvassed the opinion of airline safety professionals and airline baggage handlers concerning baggage handling tasks and working environment related causal factors. [...] A major focus of this research project was also to measure the effect of ACE and Sliding Carpet, two commercially available retro-fit baggage systems, on the risk of back injuries to baggage handlers stacking baggage within Boeing B737 narrow-body aircraft." / Doctor of Philosophy

Im Projekt wurde die Substitution von Metallen durch Holzwerkstoffe in drei ausgewählten Anwendungsfällen untersucht. Es wurde ein Arbeitstisch mit Nutenplatte, ein Schlitten für einen Rollenprüfstand und ein Vertikalförderer in Metallbauweise subsituiert. Die resultierenden drei Holzbauweisen wurden als Prototyp realisiert. Ein Vergleich der Bauweisen zeigt technische, ökonomische und ökologische Vorteile sowie Grenzen der Holzbauweisen. Förderkennzeichen: 22023611 bzw. 11NR236 / The substitution of three applications made from metals using wooden materials was the objective of the project. A workbench with a slotted table top, a sliding carriage for a roller test bench and a vertical conveying system have been substituted. As a result, three wood constructions were realized as prototypes. A comparison of the constructions shows technical, economical and ecological advantages as well as limits of the wood design itself.

This research identifies the attributes to be considered in the selection of an automated guided vehicle (AGV). A distinction is made between automated guided vehicles (AGVs) and an automated guided vehicle system (AGVS). This research is concerned only with the selection of automated guided vehicles (AGVs). A selection model is developed which forces the user to evaluate attributes. his requirements and preferences for AGV The first step of the model allows the user to enter his specifications for AGV attributes which are applicable to his production environment. The second step in the selection model is for the user to determine 8-15 attributes to use as selection criteria. In the third phase, the user inputs his preferences and priorities with respect to the attributes chosen as selection criteria in the second step. model ranks the Based on this information, the selection AGV models in the feasible set. A description of the model and a numerical example are included. Steps 1 and 2, described above, are implemented using an R:BASE™ program. The BASIC computer language was used to perform the interrogation of the user with respect to his priorities and preferences among attributes in Step 3. The IBM PC™ is the hardware chosen for running the selection model. / M.S.

Es wurde ein plattenförmiges Qualitätshalbzeug aus Spezialholzwerkstoffen für den konstruktiven Einsatz im Maschinebau, mit dem Schwerpunkt Fördertechnik entwickelt. Mit diesem Halbzeug sind ökologisch vorteilhafte Konstruktionen möglich. Entwicklungsschwerpunkte waren: einstellbare, hohe absolute und spezifische mechanische Eigenschaften mit kleinen Streuungen. Die Entwicklung wurde durch verschiedene Werkstoffprüfungen von Labor- und Industriewerkstoffen begleitet und deren Ergebnisse mittels speziell erarbeitetet Bewertungskriterien evaluiert. Weiterhin wurde das Werkstoffverhalten von diversen Holzwerkstoffen unter dynamischer Belastung klassifiziert. / A panel-shaped high quality semi-finished product made of special wood-based materials for structural applications in mechanical engineering, with a focus on materials handling technology, was developed. With said semi-finished product ecologically advantageous constructions are possible. Development priorities were: adjustable, high absolute and specific mechanical properties with little variation. The development was accompanied by various materials tests of laboratory and industrially manufactured materials, and their results were evaluated by specially developed evaluation criteria. Furthermore, the material behaviour of various woodbased materials under dynamic loading was classified.

In order to investigate the etiology of and evaluate interventions for work-related back injuries, researchers need efficient, accurate occupational exposure assessment methods suitable for large samples. The chapters in this thesis examine critical decisions using electromyography (EMG): How should exposure be measured? For what duration? Who should be measured, and how many times? Low-back EMG, or muscle activity data, was collected during 138 full-shift field measurements over 30 different job titles at 50 different worksites in 5 heavy industries: forestry, transportation, wood products, construction, and warehousing. Observations and self-reports of posture, manual materials handling (MMH), and driving exposures were collected concurrently. 1) Variability of EMG calibration measurements was investigated on right/left sides, multiple trials, 4 positions, and pre/post-shift. Position accounts for the majority of explained variability; there is little to gain by measuring multiple trials or pre- and post-shift, but measuring both sides and multiple positions is worthwhile. 2) Observation and self-report data were easier to collect and cheaper than the EMG direct measure. Costs and successful field performance need to be weighed against the added data detail when making choices about exposure assessment techniques for epidemiological studies. 3) Observed and self-reported exposures were used to predict EMG exposure metrics using mixed multiple linear regression models. Regression models using observed variables predicted 43-50% of the variability in the EMG metrics, while self-reported variables predicted 21%-36%. The observation exposure model provides a low-cost alternative to direct measurement. The self-reported exposure model should be considered with more caution. 4) Full-shift EMG data was resampled for 4, 2, and 1 hour, and for 10 and 2 minute durations to determine the optimal sampling duration. Bias was consistently low, but shorter durations had higher absolute error, percentage error, and limits of agreement. Durations of 4 and 2 hours may be acceptable but those less than 1 hour had large errors. 5) Components of EMG variance were calculated between- and within-subject, and between- industry, company, job, and post hoc grouping. Resolution, contrast, and exposure-response relationship attenuation were calculated for each grouping scheme. The post hoc scheme had the highest contrast and lowest resolution.

In order to investigate the etiology of and evaluate interventions for work-related back injuries, researchers need efficient, accurate occupational exposure assessment methods suitable for large samples. The chapters in this thesis examine critical decisions using electromyography (EMG): How should exposure be measured? For what duration? Who should be measured, and how many times? Low-back EMG, or muscle activity data, was collected during 138 full-shift field measurements over 30 different job titles at 50 different worksites in 5 heavy industries: forestry, transportation, wood products, construction, and warehousing. Observations and self-reports of posture, manual materials handling (MMH), and driving exposures were collected concurrently. 1) Variability of EMG calibration measurements was investigated on right/left sides, multiple trials, 4 positions, and pre/post-shift. Position accounts for the majority of explained variability; there is little to gain by measuring multiple trials or pre- and post-shift, but measuring both sides and multiple positions is worthwhile. 2) Observation and self-report data were easier to collect and cheaper than the EMG direct measure. Costs and successful field performance need to be weighed against the added data detail when making choices about exposure assessment techniques for epidemiological studies. 3) Observed and self-reported exposures were used to predict EMG exposure metrics using mixed multiple linear regression models. Regression models using observed variables predicted 43-50% of the variability in the EMG metrics, while self-reported variables predicted 21%-36%. The observation exposure model provides a low-cost alternative to direct measurement. The self-reported exposure model should be considered with more caution. 4) Full-shift EMG data was resampled for 4, 2, and 1 hour, and for 10 and 2 minute durations to determine the optimal sampling duration. Bias was consistently low, but shorter durations had higher absolute error, percentage error, and limits of agreement. Durations of 4 and 2 hours may be acceptable but those less than 1 hour had large errors. 5) Components of EMG variance were calculated between- and within-subject, and between- industry, company, job, and post hoc grouping. Resolution, contrast, and exposure-response relationship attenuation were calculated for each grouping scheme. The post hoc scheme had the highest contrast and lowest resolution.