The Personal Vacuum Assisted Climber or PVAC for short (as shown in Fig 2) is a new means for climbing walls. Unlike ordinary climbing methods used today, the PVAC scales walls via suction. This suction is produced by three spinning impellers within each vacuum motor, which removes air from a sealed area. A climber pulls down on a vacuum pressure release mechanism to release the vacuum. Foot stirrups are used by the climber to climb to the next higher step. This allows the strength of the climber's legs to lift his/her body reducing arm fatigue, allowing rapid ascension of any climbable wall. The overall desirables to accomplish in this project are to make a new system that is: Lightweight Improved ergonomics Easy to manufacture and produce Quieter These items were accomplished by using design tools such as Finite Element Analysis (FEA), Design for Manufacturing and Assembly (DFMA), Failure Modes and Effects Analysis (FMEA), preexisting studies (ergonomics), and testing techniques. Tests were conducted to ensure that the new PVAC is operating to safe standards. These tests will be looked at in the following areas: Sound Reduction Battery Voltage Profile Temperature Analysis Vacuum Motor Performance Friction Coefficient Experiments Lastly, future applications and new improvements were addressed so next generation systems can be made if further development ensues.

No description available.

No description available.

<p> In Part I of this thesis, the design, construction, and calibration of a twenty-one foot off-plane Eagle vacuum spectrograph, a Lyman source, and predispersion unit are described.</p> <p> In Part II, the results of an investigation of the electronic absorption spectra of the cyanogen halides, obtained with the apparatus described in Part I, are given. Several electronic absorption systems have been observed for each of the cyanogen halides. These have been correlated and assigned to electronic transitions. Vibrational analyses have been made and the excited state dimensions have been determined by a quantitative application of the Franck-Condon principle for two absorption systems of each of the cyanogen halides.</p> / Thesis / Doctor of Philosophy (PhD)

<p> A surface station consisting of a sample manipulator and transfer system was developed to allow the study of plasma - first wall interactions in ALCATOR at M.I.T. A disc shaped probe is located at the plasma edge and rotated past an aperture in a shield to obtain time resolved data. Samples can be analysed in situ or transported under vacuum to McMaster University. The transfer process from the surface station to the 'vacuum suitcase' is accomplished by means of pressure locks.</p> / Thesis / Master of Engineering (MEngr)

Bending wood dates back to antiquity in the form of baskets from willow branches and when boats were no longer made of hollowed out logs. Fresh growth willow twigs are readily bent into practically any shape; however, when wood has been separated from the tree and dried it is more rigid, difficult to bend, and breakable. Steamed wood is less rigid since adding moisture and heat to wood results in plasticization. Steaming at atmospheric pressure is the common technique for wood bending where diffusion prevails as the predominant mechanism governing moisture movement. Applications using conventional atmospheric steaming are time consuming and can result in failed bends. While other wood plasticization methods exist, Vacuum Steam Technology offers a promising method that utilizes pressure differentials to accelerate the addition of steam to wood due to water vapor bulk flow and subsequently an accelerated temperature rise and moisture addition. The objectives of this work were: (1) determine whether cycles of vacuum and steaming could significantly improve the plastic-deformable state relative to the classic process of atmospheric steaming given equivalent treatment times when beginning with low moisture content (<10%) maple, and (2) compare the work required to bend to form between Vacuum Steam Technology treated maple and atmospheric-steamed maple when beginning with low moisture content (<10%) specimens. A procedure for Vacuum Steam Technology to enable rapid plasticization of maple specimens from a kiln-dried state was developed. Kiln dried maple specimens were either treated according to the Vacuum Steam Technology procedure or were atmospherically steamed for a time equivalent to the Vacuum Steam Technology treatment and then bent into a 180° semi-circular form. Vacuum Steam Technology treated specimens had 0 failed bends whereas the atmospheric steamed specimens resulted in 39% failed bends. Vacuum Steam Technology treated specimens resulted in 17% less work to bend. The results clearly indicate that Vacuum Steam Technology is a superior technique for attaining a plastic deformable state prior to bending when beginning with low moisture content maple. Additional results included time to temperature, rate of moisture content change, final moisture contents, specific gravity influence. / Master of Science

The purpose of this study was to determine the effects of storage temperature and film oxygen transmission rate (OTR) on toxin development by Clostridium botulinum in refrigerated raw vacuum packaged croaker fillets, and to determine if toxin development precedes microbiological and/or organoleptic spoilage. Raw croaker fillets were vacuum packaged in oxygen-permeable films (OTR of 10,000 cc/m2/24hr or 3,000 cc/m2/24hr) and stored at either 4ºC or 10ºC. Type 83F, 17 Type B, Beluga, Minnesota, and Alaska nonproteolytic strains of C. botulinum were used to inoculate fish prior to vacuum packaging. At both temperatures, microbial spoilage preceded toxin production in fillets vacuum packaged in both film types. At 4ºC microbial spoilage occurred after approximately 7 days for fillets vacuum packaged in the 10,000 cc/m2/24hr OTR film and after 8 days for fillets vacuum packaged in the 3,000 cc/m2/24hr OTR film. However, toxin was not detected until day 8. At 10ºC microbial spoilage occurred after approximately 3 days for fillets vacuum packaged in the 10,000 cc/m2/24hr OTR film, while toxin production occurred on day 5. For fillets vacuum packaged in the 3,000 cc/m2/24hr OTR film microbial spoilage occurred after 4 days. However toxin production did not occur until day 6. In contrast, at both temperatures toxin production preceded or coincided with organoleptic spoilage in fillets vacuum packaged in both film types. At 4ºC organoleptic spoilage occurred after 10 days for fillets packaged in the 10,000 cc/m2/24hr OTR film and after 9 days in the 3,000 cc/m2/24hr OTR film, while toxin production occurred on day 8. At 10ºC organoleptic spoilage occurred after 6 days for fillets packaged in the 10,000 cc/m2/24hr OTR film, and toxin was detected on day 5. For fillets packaged in the 3,000 cc/m2/24hr OTR film and stored at 10ºC, organoleptic spoilage occurred after 6 days, while toxin production occurred on day 6. Although toxin production preceded or coincided with organoleptic spoilage in both film types, this may have been because samples were presented on ice, which could have masked potential odors. This study shows that there are not significant differences between these film types when it comes to microbial and organoleptic spoilage. Therefore lower OTR films, such as 3,000 cc/m2/24hr film, may be used to vacuum package Atlantic croaker. / Master of Science in Life Sciences

Outside the world of music the transistor has supplanted the vacuum tube. Transistors do the same sort of job as vacuum tubes but they use germanium or silicon in their manufacture, thus the current is produced in a solid state, rather than a vacuum. Most electronic devices are built with solid state technology. Exceptions are some musical instrument amplifiers and some audiophile grade stereo gear. For the users of this equipment the transistor is unsatisfactory both spiritually and with respect to sound. The need for tubes has become specialized, to the point where designers are designing amplifiers to the specifications of available tubes. The relative scarcity of these gems makes the notion of manufacturing specific tubes under exacting conditions, in relatively small quantities, attractive. A place to make these glass jewels should respect their history, use, and the careful manufacturing techniques required to make them. It is the basilica of the church of the distorted guitar sound. / Master of Architecture

A paucity of literature exists on the Independent System analysis of adjacent, parallel transition dipoles. Applying this theory and certain spectral information semiemperical calculations were made to predict absorption profiles and band intensities. To aid in the assignment of the 7*+7 absorption bands it was necessary to obtain the vacuum ultraviolet spectra of cyclohexane and cyclohexene. Because the spectra of these molecules contained sharp, atomic-like absorption bands a Rydberg series could be fitted to certain absorptions, thus the determination of their ionization potentials. Using Independent System analysis profiles and intensities of 7*+q-- absorption bands ins 'several methyl substituted 1,4- cyclohexadienes and isotetralin were predicted where general agreement was found with observed experimental spectra.

A batch vacuum frying system, which processes fruits and vegetables, includes a frying pan, a surface-condenser, and a vacuum pump. With health and safety issues in mind, this research focused on developing a modified surface-condenser to prevent cavitation of the vacuum pump. The final oil-content was reduced by centrifugal de- oiling of the product under vacuum, which make the product healthier than what is currently available. The de-oiling mechanism consists of a centrifuge with a motor attached to the basket shaft, rotating up to 750 rpm (63 g units). The condenser consists of a (counter- flow) spiral-coil heat exchanger (SHE) connected to a refrigeration system that uses R404a refrigerant. De-oiling for 40 s at 300 and 750 RPM removed up to 67% and 72% of the chip’s surface oil, respectively. At 750 RPM for 10 s, 40 s, and 60 s the oil-content was reduced by 38%, 44%, and 51%, respectively. The convective heat transfer coefficient (h) of the frying oil was determined at 120°C and 140°C using the lumped capacitance method. The h-values were 217±13 W/m2K (120°C) and 258±37 W/m2K (140°C) using a copper-ball thermocouple. The h- values increased to 3.6 times during the boiling period. COMSOLTM Multiphysics was used to model the heat transfer in the vacuum fryer pan. Based on the simulation results, a 1.5 cm thick insulation material was installed in the fryer to reduce the energy losses. The refrigeration system operates at Tevap = -26°C and Tcond = 50°C with 26°C sub-cooling. Sensitivity analysis showed that the system Coefficient of Performance (COP) was about 3.87 at these conditions and compressor power requirement (CPR) was 74 W (85% efficiency) when frying 30 g of potatoes slices. The best results were obtained at Tevap = -10°C and Tcond = 40°C with 26°C sub-cooling and superheat of 5°C. The predicted COP was 4 and the CPR 70 W. The ice-formation on coils reduced the condensation rate. Reducing the refrigerant temperature to -10°C (from -26°C) reduced the condensation rate by 30%. These results show a more effective vacuum frying system for high-quality fruits and vegetables than the system previously used.