Optimization of roughing operations in cnc machining for rapid manufacturing processes

This paper presents a method for optimizing roughing operations in CNC machining particularly for parts production through a subtractive rapid manufacturing process. The roughing operation in machining is primarily used to remove the bulk of the material and to approximately shape the workpiece towards the finish form. The manufacturing process described utilizes a 3-axis CNC machine with an indexable 4th axis device that is used to hold and rotate the workpiece. The method used is derived from the multiple approaches in roughing operations that differ in the number and the angle of the orientations. Most of the machining parameters are generalized throughout the process to allow some automation in generating the machining program. Overall, the performance of each of the approaches is evaluated based on the lowest machining time to produce the part

Caribou, river and ocean: Harvaqtuurmiut landscape organization and orientation

The Harvaqtuurmiut were an Inuit society whose territory was Harvaqtuuq—the lower Kazan River—between the outlet of Hikuligjuaq (Yathkyed Lake) and the river’s mouth at Qamani’tuaq (Baker Lake). The Harvaqtuurmiut lived a completely inland existence and their subsistence revolved largely around the migration of caribou. In Harvaqtuurmiut perception, the landscape was organized and given orientation by three important influences: the migration of caribou; the flow of the river; and the relative location of the ocean. The organizing and orienting effects of these three influences are demonstrated through an analysis of Harvaqtuurmiut place names. Concepts related to the flow of the river and the relative location of the ocean were imbedded in the Inuktitut language at the time of Inuit migration to Harvaqtuuq in the mid-19th century. The environmental force of the caribou migration became very influential in Harvaqtuurmiut perception of landscape organization and orientation only after they had adapted to subsistence inland.Les Harvaqtuurmiut habitaient le territoire Harvaqtuuq — le bas de la rivière Kazan — situé entre la décharge de Hikuligjuaq (le lac Yathkyed) et l’embouchure de la rivière à Qamani’tuaq (le lac Baker). Les Harvaqtuurmiut vivaient de façon recluse et leur subsistance était principalement assurée par la migration du caribou. Selon la perception des Harvaqtuurmiut, le paysage était structuré et orienté par trois influences majeures: la migration du caribou, l’écoulement de la rivière et la proximité de l’océan. Les effets de l’organisation et de l’orientation de ces trois influences sont expliqués par l’analyse de toponymes harvaqtuurmiut. Les concepts concernant l’écoulement de la rivière et la proximité de l’océan étaient enchâssés dans la langue inuktitut au moment de la migration des Inuit vers Harvaqtuuq au milieu du 19ième siècle. La force de la migration du caribou sur l’environnement devint une influence très importante sur la perception des Harvaqtuurmiut concernant l’organisation et l’orientation du paysage seulement après que ceux-ci se soient adaptés à un mode de subsistance à l’intérieur des terres

Spatial diversification, dividend policy, and credit scoring in real estate

Built on the foundation of economic principles, real estate offers many pursuits of academic discovery within the realm of finance. This dissertation examines three areas of real estate finance. In the first chapter, I use the unique real estate characteristics of heterogeneity, immobility, and localized markets to examine the spatial aspects of large-scale commercial real estate portfolios. The results demonstrate a clear need for portfolio managers to diversify properties based upon distances between properties. The second chapter examines another large-scale real estate portfolio, the real estate investment trust, which is held by investors seeking dividend income. Despite the importance of dividend payouts to investors, current real estate literature does not fully explain the dividend policy of REITs. I find that REITs base dividend payouts on contemporaneous earnings, the level of dividends paid last period, and firm volatility. For real estate investors that desire income based upon debt instruments, the last chapter examines the prepayment and default of mortgage instruments using credit scoring. I address the research question of how credit scoring affects mortgage pricing. The findings indicate a need to include credit scores as a state variable in a mortgage option pricing model. Overall, each chapter furthers our understanding of real estate finance

A MODEL OF ENTRY-EXIT DECISIONS AND CAPACITY CHOICE UNDER DEMAND UNCERTAINTY

Many investment decisions of agribusiness firms such as when to invest in an emerging market or whether to expand the capacity of the firm involve irreversible investment and uncertainty about demand, cost or competition. This paper uses an option-value model to examine the factors affecting an agribusiness firm's decision whether and how much to invest in an emerging market under demand uncertainty. Demand uncertainty and irreversibility of investment make investment less desirable than the net present value (NPV) rule indicates. The inactive firm is more reluctant to enter the market when it takes into account demand uncertainty because it preserves the opportunity of making a better investment later. The active firm is more reluctant to abandon the investment because there is an option value of keeping the operation alive. There is a greater distance between the entry and exit thresholds under the option-value approach than under the NPV rule due to demand uncertainty. The results have implications for agribusiness decision-making to understand and respond to uncertainty.agribusiness decision-making, demand uncertainty, entry-exit decisions, net present value, real options, remote sensing, Demand and Price Analysis,

Cutting Tools in Finishing Operations for CNC Rapid Manufacturing Processes: Simulation Studies

Over the years, CNC machining has been widely used in producing metal parts with high accuracy and reliable quality. A distinct process planning approach that utilizes an indexing device to hold the workpiece has extended CNC applications into the realm of rapid manufacturing (CNC-RM) processes. This study improves the implementation of this technology by providing a methodology for integrating the tools into finishing processes. It aims to enhance the process efficiency by minimizing the stair-casing effect of layer removal and so improve the quality of machined parts. In order to achieve this, finishing operations are executed using different types of end mill tools to cater for specific surfaces on parts. Several simulations are carried out to verify the method and implications. The present findings indicate the advantages of the developed approach in terms of cutting time and the minimisation of excess volumes left on parts. It is shown that using different cutters for finish cuts will improve the capabilities of CNC machining in rapid manufacturing applications

Selenium supplementation of lactating dairy cows: effects on milk production and total selenium content and speciation in blood, milk and cheese

Forty-multiparous Holstein cows were used in a 16-wk continuous design study to determine the effects of either selenium (Se) source, selenized yeast (SY) (derived from a specific strain of Saccharomyces cerevisiae CNCM I-3060 Sel-Plex®) or sodium selenite (SS), or inclusion rate of SY on Se concentration and speciation in blood, milk and cheese. Cows received ad libitum a TMR with 1:1 forage:concentrate ratio on a dry matter (DM) basis. There were four diets (T1-T4) which differed only in either source or dose of Se additive. Estimated total dietary Se for T1 (no supplement), T2 (SS), T3 (SY) and T4 (SY) was 0.16, 0.30, 0.30 and 0.45 mg/kg DM, respectively. Blood and milk samples were taken at 28 day intervals and at each time point there were positive linear effects of SY on Se concentration in blood and milk. At day 112 blood and milk Se values for T1-T4 were 177, 208, 248, 279 ± 6.6 and 24, 38, 57, 72 ± 3.7 ng/g fresh material, respectively and indicate improved uptake and incorporation of Se from SY. While selenocysteine (SeCys) was the main selenised amino acid in blood its concentration was not markedly affected by treatment, but the proportion of total Se as selenomethionine (SeMet) increased with increasing inclusion rate of SY. In milk, there were no marked treatment effects on SeCys content, but Se source had a marked effect on the proportion of total Se as SeMet. At day 112 replacing SS (T2) with SY (T3) increased the SeMet concentration of milk from 36 to 111 ng Se/g and its concentration increased further to 157 ng Se/g as the inclusion rate of SY increased further (T4) to provide 0.45 mg Se/kg TMR. Neither Se source nor inclusion rate effected the keeping quality of milk. At day 112, milk from T1, T2, and T3 was made into a hard cheese and Se source had a marked effect on total Se and the proportion of total Se comprised as either SeMet or SeCys. Replacing SS (T2) with SY (T3) increased total Se, SeMet and SeCys content from 180 to 340 ng Se/g, 57 to 153 ng Se/g and 52 to 92 ng Se/g, respectively. Key words: dairy cow, milk and cheese, selenomethionine, selenocysteine, milk keeping qualit