Using data from temporary and permanent sample plots various functions describing different stand parameter relationships were developed for P. patula growing at Sao Hill, Southern Tanzania. The functions include equations for: a Weibull diameter distribution, a single tree diameter increment, stand basal area, mortality, and height/diameter relationship. Also site index curves based on a Chapman-Richards equation were constructed, and a compatible taper/volume estimation system was developed. The functions were integrated into a micro-computer model SIMUL in BASIC language. The model is capable of estimating saw-log and pulp-log volumes for different spacings and thinning regimes. Inputs to the model are: initial and simulation ages, stocking/ha, stand mean and standard deviation of diameter at breast height (dbh), basal area/ha, site, dominant height, and minimum diameters and lengths of saw-logs and pulplogs. The output gives yearly values/ha for; stocking, total volume, total basal area/ha, means for dbh, height and tree volume, mortality number and volume/ha, and volumes of saw-logs and pulplogs as out-turn from subsequent thinnings and the final clearfelling. Validation with independent data showed that the model works satisfactorily. Experimental runs at different levels of spacing and thinning regimes suggested that the current thinning schedule at Sao Hill is too heavy and results in loss in total volume. The highest utilizable volumes (mainly saw logs) may be obtained by using the current spacing of 2.7 x 2.7m followed by one thinning at the age of about 11 years to leave about 1100 stems/ha, with a rotation age of 25 years. This treatment is also justified economically giving the highest present value at an interest rate of 3%. The current rotation age 15 years (unthinned) for the production of pulp wood only is ideal to produce the required dimensions (10-20 cm diameter) of pulp logs. SIMUL is recommended for use at Sao Hill and the technique may be adopted for other plantation species in Tanzania with new parameter estimates for the equations.

The purpose of a greenhouse is to maintain desirable growing conditions for plants during the different seasons of the year. The glass-covered greenhouse has been found to be suitable for this purpose through many yeara of use and improvement. It has been very popular for providing a controlled environment in which out-of-season crops can be grown and also as a research house for the study of plant growth. The sturdy construction required to support the weight of glass involves a high initial cost. With the development of plastic sheeting suitable for use as a glazing material, a new type of greenhouse has evolved. Greenhouses covered with plastic do not require the sturdy structure necessary to support glass, although a permanent construction may be used. To date the plastic greenhouse has found its greatest use as a temporary low cost structure. The possibility of growing crops intolerant of frost during the winter months in the southwestern United States where mild winters keep heating costs low, has increased interest in plastic greenhouses. Since high temperatures occur during the summer months in the Southwest, cooling as well as heating have to be provided if the greenhouse is to be operated through the entire year. This study was designed to measure the modification of the environment within a plastic greenhouse and to evaluate the growth response of tomatoes under these conditions. Studies were conducted to determine the temperatures which could be maintained in a plastic greenhouse during the summer, winter and spring seasons. The growth response of tomatoes under plastic was studied using winter and spring variety trials.

Bottomland hardwood stands of the Mid-South region of the United States are some of the most productive forests in the country. A large percentage of these stands are owned by nonindustrial private forest landowners, who have little information on which to base management decisions. These stands are, therefore, a largely unmanaged and under-utilized reserve of high quality hardwoods. To provide landowners with a decision-making tool for comparing management scenarios, a growth and yield study was initiated in 1981. One hundred and fifty permanent plots were installed in red oaksweetgum stands. The study has been remeasured three times over the past 35 years. New plots were added when losses occurred due to natural disasters or harvesting. Stand level (Iles 2008), log grade volume distribution (Banzhaf 2009), and diameter distribution (Howard 2011) models were developed as component models of the overall growth and yield system. This study completes the modeling effort by developing individual tree equations for percent annual diameter growth and survival. Equations were constructed using linear, non-linear, and logistic regression techniques. The best set of developed equations was selected based on biological consistency, joint behavior when inserted into the growth and yield computer model, and the performance of each plot’s predicted future yield when compared to its observed data at the next projection period. Final independent stand level variables for the two models included age, diameter at breast height, trees per acre, and average height of dominant trees. Percent diameter growth and survival equations exhibited high fit statistics and when coupled with the other equations in the computer model, produced estimates for trees per acre, basal area, arithmetic and quadratic mean diameters with low bias and root mean squared error. The resulting growth and yield simulator implemented in Microsoft Visual Basic® Editor within Microsoft Excel® enables forest professionals and landowners to make better management decisions for their red oak-sweetgum mixture bottomland hardwood stands by projecting current forest inventories into the future, predicting average yields, and evaluating and comparing forest management scenarios.

This study explores the biophysical potential and economic attractiveness of black spruce (Picea mariana) regeneration in eastern Canada under future climate changes. It integrates process-based ecosystem model simulated forest productivities from three major global climate models (GCMs), growth and yield formulations specific to black spruce and economic analyses to determine the overall investment value of black spruce, both including and excluding carbon sequestration benefits. Net present value (NPV) was estimated to represent the financial attractiveness of long-rotation forest plantations through time. It was assumed that stands would not be harvested at volumes less than 80 m3 ha-1. The price of stumpage was set to $20 m-3, stand establishment cost was set to $500 ha-1, and the discount rate was considered at 4%, with sensitivity analyses conducted around these assumptions. The growth and yield of black spruce was simulated for an extreme future climate scenario – IPCC-RCP 8.5. The results suggested a general North-South gradient in forest productivity where gross merchantable wood volumes increased with decreasing latitudes. This pattern was also observed in NPVs, with higher values projected for the southern portion of the study area. Based on the base economic assumptions and sensitivity analyses, study results suggested that black spruce plantations are not economically attractive, unless carbon sequestration benefits of at least $5 ton-1 CO2 are realized. Further sensitivity analyses showed that discount rate plays a significant role in determining the optimal harvest age and value. Furthermore, the optimal harvest rotation age increases with increasing carbon price by approximately 9 to 18 years. / Thesis / Master of Science (MSc)

This study deals with analysis of the agricultural company layout. The utilization of agricultural areas is optimized with such a sowing technique that leads to the highest harvest profit. All these issues are being solved by the conversion to the linear programming model which is the most resembling to the combination of production planning and allocation problem. A case study is based on actual data given by Agrofarma Týnec, s.r.o. company. The 48 sections of field in different proportion are taken in consideration as well as five different crops. The study tries to deal with more options taking in account different trade prices of set commodities and a hectare sowing limitation. The main model anticipates pessimistic trade prices expectations and does not restrict hectare sowing with single crops. The model is followed by the price coefficient analysis that gives the price level to be kept to let the computed solution be optimal. Lingo13.0 was used as an optimization software.

A weight function based modified strip-yield model is adapted to include the mode I effects of roughness induced crack closure. The weight function methodology is verified for arbitrary mixed mode loading conditions under load levels experienced in fatigue crack growth. A rough crack geometry is simulated as a sine wave fitted to a sawtooth defined by an asperity angle and period. Additional mode I crack closure due to mode II sliding of crack faces is calculated and incorporated into the strip-yield model by lengthening and shortening the crack face elements. Simulations of fatigue crack growth using the newly developed model are examined via a design and analysis of computer experiments. The effects of model parameters are identified. Combined roughness and plasticity induced crack closure for long cracks is studied.

The purpose of greenhouse crop systems is to generate a high quality product at high production rates, consistently, economically, efficiently and in a sustainable way. To achieve this level of productivity, accurate monitoring and control of some processes of the entire biophysical system must be implemented. In addition, the proper selection of actions at the strategic, tactical and operational management levels must be implemented.Greenhouse management relies largely on human expertise to adjust the appropriate optimum values for each of the production and environmental parameters, and most importantly, to verify by observation the desired crop responses. The subjective nature of observing the plant responses, directly affects the decision-making process (DMP) for selecting these `optimums'. Therefore, in this study several decision support systems (DSS) were developed to enhance the DMP at each of the greenhouse managerial levels.A dynamic greenhouse environment model was implemented in a Web-based interactive application which allowed for the selection of the greenhouse design, weather conditions, and operational strategies. The model produced realistic approximations of the dynamic behavior of greenhouse environments for 28-hour simulation periods and proved to be a valuable tool at the strategic and operational level by evaluating different design configurations and control strategies.A Web-based crop monitoring system was developed for enhancing remote diagnosis. This DSS automatically gathered and presented graphically environmental data and crop-oriented parameters from several research greenhouses. Furthermore, it allowed for real-time visual inspection of the crop.An intelligent DSS (i-DSS) based on crop records and greenhouse environment data from experimental trials and from commercial operations was developed to characterize the growth-mode of tomato plants with fuzzy modeling. This i-DSS allowed the discrimination of "reproductive", "vegetative" and "balanced" growth-modes in the experimental systems, and the seasonal growth-mode variation on the commercial application.An i-DSS based on commercial operation data was developed to predict the weekly fluctuations of harvest rates, fruit size and fruit developing time with dynamic neural networks (NN). The NN models accurately predicted weekly and seasonal fluctuations of each variable, having correlation coefficients (R) of 0.96, 0.87 and 0.94 respectively, when compared with a dataset used for independent validation.

Cost effective high volume manufacture of solid oxide fuel cells (SOFCs) is a major challenge for commercial success of these devices. More than fifteen processing methods have been reported in the literature, many of which could be used in various combinations to create the desired product characteristics. For some of these processes, high volume manufacturing experience is very limited or non-existent making traditional costing approaches inappropriate. Additionally, currently available cost models are limited by a lack of incorporation of device performance requirements. Therefore, additional modeling tools are needed to aid in the selection of the appropriate processing techniques prior to making expensive investment decisions. This project describes the development of a SOFC device performance model and a manufacturing process tolerance model. These models are then linked to a preliminary cost model; creating a true multi-process, performance based cost model that permits the comparison of manufacturing cost for different combinations of three processing methods. The three processing methods that are investigated are tape casting, screen printing, and sputtering. . This model is capable of considering production volume, process tolerance and process yield, in addition to the materials and process details. Initial comparisons were performed against processes used extensively within the solid oxide fuel cell industry and the cost results show good agreement with this experience base. Sensitivity of manufacturing costs to SOFC performance requirements such as maximum power density and operation temperature are also investigated.

Fatigue damage of aluminium alloys is one of the key concerns in transport industries, particularly in the aerospace industry. The purpose of the project is to develop new knowledge and techniques against fatigue failure for these industries through a systematic investigation of fatigue resistance and crack growth behaviours of aluminium alloys. Fatigue and fracture mechanics have been investigated analytically, numerically and experimentally in this project. Overload transient effect on fatigue crack growth has been examined by considering various parameters including crack closure, overload ratio (OLR), load ratio (R ratio), baseline stress intensity factor range, (∆K)_BL and geometry. It was found that crack closure can be correlated qualitatively and quantitatively to all other parameters associated with overload transient behaviour. It is proposed that the effect of crack tip plasticity on the non-linearity of the compliance curve can be separated to obtain reliable crack closure measurement. In this project, different methods are used to better understand the transient retardation process so that the damage tolerance design (DTD) of the components made of aluminium alloys can be enhanced. Another important parameter for fatigue and damage tolerance design (DTD) of engineering components is the threshold stress intensity factor range for fatigue crack growth, ∆K_th. A small variation in identification of ∆K_th can lead to a big change in overall estimation of fatigue life. In this project, an analytical model has been developed for aluminium alloys by fitting an analytical curve with raw crack growth data in order to identify the ∆K_th. This model has the capacity to identify ∆K_th for different aluminium alloys at various R ratios. There is a great demand for enhanced fatigue life of aluminium alloys in the transport industry. This project has carried out a detailed investigation of electromagnetic treatment (ET) in the form of electropulsing treatment to develop an efficient technique for fatigue resistance enhancement. ET parameters including the treatment intensity, treatment time and the number of applications have been optimised. It is suggested that the duration of ET treatment can be used as the main parameter among all these to control the fatigue resistance of the aluminium alloy. The improvement in fatigue resistance has been explained by the change in microhardness and conductivity of aluminium alloy due to ET. Additionally, the fracture morphology was analysed using scanning electron microscopy (SEM). The precipitates and dislocation characteristics were also studied using transmission electron microscopy (TEM). The outcomes of this investigation will help improve structural integrity by enhancing fatigue resistance of aluminium alloys.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第18664号 / エネ博第309号 / 新制||エネ||63(附属図書館) / 31578 / 京都大学大学院エネルギー科学研究科エネルギー応用科学専攻 / (主査)教授 大垣 英明, 教授 白井 康之, 教授 松田 一成 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM