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Master of Agribusiness / Department of Agricultural Economics / Major Professor Not Listed / Self-propelled forage harvesters are used to make feed for livestock. Producers prefer forage made with these machines because they are able to deliver a feed value that enables improved productivity of their animals in terms of milk production for dairy animals and weight gain for beef animals. Self-propelled forage harvesters are able to make a variety of feed from different crops, including whole-plant corn silage, earlage, and haylage, among others. The self-propelled forage harvester is a complex and expensive piece of machinery for a producer to own. The self-propelled forage harvester market in the United States is a growing market, but small when compared to other equipment such as combines. In today’s environment, productivity is crucial to the success of the agricultural producer. Self-propelled forage harvesters are no exception. Growth of the self-propelled forage harvester market is reflected in increased unit sales, total horsepower sold, and average horsepower of the selfpropelled forage harvesters sold in the United States. This study looks at changes in the number and size of self-propelled forage harvesters being purchased and what factors might be driving those changes. This study found that the amount of milk produced, the type of customer purchasing the equipment, and the average price of milk a producer received explained 81.2% of the variation in the number of self-propelled forage harvesters sold from 2000- 2014. Study results also show that the size of dairy operation, the type of customer purchasing the equipment, and the average price of milk explained 88% of the variability in total horsepower of self-propelled forage harvesters sold from 2000-2014. Finally, the size of dairy operation that a typical cow comes from, the type of customer purchasing the equipment, and the average price of corn were able to explain 98% of the variation of average horsepower of self-propelled forage harvesters over that same time period. The model and analysis will be shared with product planners from John Deere as they develop new machine specifications for self-propelled forage harvesters in the future.

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In this work, the development of a Thermoelectric Generator on Flexible Silicon Fabric is explored to extend silicon electronics for flexible platforms. Low cost, easily deployable plastic based flexible electronics are of great interest for smart textile, wearable electronics and many other exciting applications. However, low thermal budget processing and fundamentally limited electron mobility hinders its potential to be competitive with well established and highly developed silicon technology. The use of silicon in flexible electronics involve expensive and abrasive materials and processes. In this work, high performance flexible thermoelectric energy harvesters are demonstrated from low cost bulk silicon (100) wafers. The fabrication of the micro- harvesters was done using existing silicon processes on silicon (100) and then peeled them off from the original substrate leaving it for reuse. Peeled off silicon has 3.6% thickness of bulk silicon reducing the thermal loss significantly and generating nearly 30% more output power than unpeeled harvesters. The demonstrated generic batch processing shows a pragmatic way of peeling off a whole silicon circuitry after conventional fabrication on bulk silicon wafers for extremely deformable high performance integrated electronics. In summary, by using a novel, low cost process, this work has successfully integrated existing and highly developed fabrication techniques to introduce a flexible energy harvester for sustainable applications.

Hybrid energy harvesters (HEHs) targeting multiple energy forms have been drawing increasing interest in recent years. While large scale photovoltaic power plants are capable of providing energy for domestic usage, research has also been focused on kinetic energy harvester with less power output which can be integrated into self-powered electronics such as implantable device, remote wireless sensor, wearables, etc. A number of successful designs of hybrid energy harvesters have been demonstrated which could scavenge solar and kinetic energy simultaneously. However the structures remain complicated; the majority of the designs involve different types of energy harvesters connected in series, which involves complex fabrication processes. Here, a simple structure based on a p-n junction piezoelectric nanogenerator (NG) was designed. The utilization of columnar piezoelectric n-type ZnO nanorods coated with light absorber layer enabled the device to harvest both kinetic and solar energy. This was adapted to either form a N719-based dye-sensitized solar cell (N719-HEH), or a perovskite solar cell (PSC-HEH). To allow high processing temperatures while maintaining mechanical flexibility, Corning© Willow™ (CW) glass substrate was used and compared to the more common ITO/PET. CW showed 56% lower charge transfer resistance and a related 4 times fold increase in power conversion efficiency for N719-HEHs. Oscillation (NG effect) and illumination (PV effect) testing indicated that both N719-HEHS and PSC-HEHs operated as kinetic and solar energy harvesters separately, with the current generated by the photovoltaic orders of magnitude greater than it from mechanical excitation. In addition, under illumination, both N719-HEHs and PSC-HEHs demonstrated further current output enhancement when oscillation was applied. The fact that the current output under NG+PV condition was higher than the summation of current output achieved under NG and PV conditions individually, suggests the piezoelectric potential originated from ZnO affected the charge dynamics within the devices. Thus, HEHs with enhanced output were successfully designed and developed.

Low-power requirements of contemporary sensing technology attract research on alternate power sources that can replace batteries. Energy harvesters function as power sources for sensors and other low-power devices by transducing the ambient energy into usable electrical form. Energy harvesters absorbing the ambient vibrations that have potential to deliver uninterrupted power to sensing nodes installed in remote and vibration rich environments motivate the research in vibrational energy harvesting. Piezoelectric bimorphs have been demonstrating a pre-eminence in converting the mechanical energy in ambient vibrations into electrical energy. Improving the performance of these harvesters is pivotal as the energy in ambient vibrations is innately low. The present work is organized in three major sections: firstly, audit of the energy available in a vibrating source and design for effective transfer of the energy to harvesters, secondly, design of vibration energy harvesters with a focus to enhance their performance, and lastly, identification of key performance metrics influencing conversion efficiencies and scaling analysis for MEMS harvesters. Typical vibration levels in stationary installations such as surfaces of blowers and ducts, and in mobile platforms such as light and heavy transport vehicles, are determined by measuring the acceleration signal. The frequency content in the signal is determined from the Fast Fourier Transform. A method of determining the energy associated with the vibrating source and the associated power using power spectral density of the signal is proposed. Power requirements of typical sensing nodes are listed with an intent to determine the adequacy of energy harvesting. Effective transfer of energy from a given vibration source is addressed through the concept of dynamic vibration absorption, which is a passive technique for suppressing unintended vibrations. Optimal absorption of energy from a vibration source entails the determination of absorber parameters such as resonant frequency and damping. We propose an iterative method to obtain these parameters for a generic case of large number of identical vibration absorbers resembling harvesters by minimizing the total energy absorbed by the system. The proposed method is verified by analysing the response of a set of cantilever absorber beams placed on a vibrating cantilever plate. We find, using our method, the values of the absorber mass, resonant frequency and damping of the absorber at which significant amount of energy supplied to the system flows into the absorber, a scenario which is favourable for energy harvesting. We emphasize through our work that monitoring energies in the system and optimizing their flow is both rational and vital for designing multiple harvesters that absorb energy from a given vibration source optimally. Enhancing the performance of piezoelectric energy harvesters through a multilayer and, in particular, a multistep configuration is presented. Partial coverage of piezoelectric material in steps along the length of a cantilever beam results in a multistep piezoelectric energy harvester. We find that the power generated by a multistep beam is almost twice of that generated by a multilayer harvester made out of the same volume of polyviny-lidine fluoride (PVDF), further corroborated experimentally. Improvements observed in the power generated prove to be a boon for weakly coupled, low pro le, piezoelectric materials. Thus, in spite of the weak piezoelectric coupling observed in PVDF, its energy harvesting capability can be improved significantly by using it in a multistep piezoelectric beam configuration. Besides, the effect of piezoelectric step length and thickness in a piezoelectric unimorph harvester and performance metrics such as piezoelectric coupling factor and efficiency of conversion are presented. Modeling of a hybrid energy harvester composed of piezoelectric and electromagnetic mechanisms of energy conversion motivated by the need to determine the contribution of each domain to the power generated by the harvester is presented, particularly, when multiple domains exist in a single harvester. Two exclusive schemes of energy transduction are represented using equivalent circuits, which allow modeling any additional transduction scheme employed in the hybrid harvester with relative ease. Furthermore, a method of determining optimal loads in the respective domains using the equivalent circuit of the hybrid harvester is presented. Four different hybrid energy harvesters were fabricated and evaluated for their performance in comparison with that estimated from the proposed models. Additionally, scaling laws for hybrid energy harvesters are presented. The power developed by both piezoelectric and electromagnetic domains is observed to decrease with width and length cubed. Power indices and figures of merit in a hybrid harvester are proposed and are used to estimate the efficiencies of the four fabricated hybrid harvesters. The important design parameters for micro scale harvesting are identified by performing scaling analysis on MEMS piezoelectric harvesters. Performance of energy harvesters is directly related to the harvester attributes, viz., size, material, and end-mass. Depending on the contribution from each attribute, the power developed by MEMS harvesters can vary widely. A novel method of delineating the power developed by a harvester using five exclusive factors representing scaling, composition, inertia, material, and power (SCIMP) factors is presented. Although the proposed method can be extended to bi-morph and multilayer harvesters, in the present work, we elucidate it by applying it to a MEMS unimorph. We also present a unique coupling factor that ensures maximum power factor in a harvester. As any tiny increment in the power generated would considerably improve the power densities of MEMS harvesters, we focus on enhancing the power developed by maximizing each of the five exclusive factors irrespective of material and size. Furthermore, we demonstrate the competence of the proposed method by applying it on nine different MEMS harvesters reported in the literature. Considering the close match between the reported and predicted performance, we emphasize that monitoring the proposed factors is sufficient to attain the best performance from a harvester.

Today, there are few studies about risks and accidents at work with harvesters, but each study creates a better basis to prevent future accidents to occur. The purpose of this study was to examine machine driver's perception of risks and accidents at work with harvesters Komatsu 901, 901TX. The focus was on the drivers of the model Komatsu 901 and 901TX, a common thinning and final felling machine in Sweden. Results show that there are deficiencies that are recurring on multiple machines. These deficiencies also have a connection to the actual accidents. Half of the drivers felt that there were defects (flaws) around the handle and the footboard and only one driver had access to the alarm box. The drivers believe the current structure of harvester can be improved but is not always taken seriously when they make their requests for improvements to reduce risks.

[Abstract]: Yield maps provide essential information for the spatial analysis and evaluation of crop production management at a within field level. Technology has been developed to conduct yield mapping in various crops including grain, potatoes and forage, but as yet no technology exists for yield mapping sugar cane. The chopper harvester is the most common form ofmechanical harvester for sugar cane. Therefore, the goal of this research is to develop a yield mapping system for the chopper type sugar cane harvester.After a review, it is proposed that a suitable accuracy goal for the sugar cane mass flow sensor would be ‘less than 5% cumulative measurement error, 95% of the time (2 standard deviations), measured over a 100m2 harvest area’.Existing mass flow sensors for other crops are reviewed.Based on this review four potential techniques are proposed to measure the mass flow rate of sugar cane. These were defined as the chopper power, elevator power and feed roller separation and weigh pad. These weretested simultaneously by placing various sensors on a single harvester and comparing the sensor outputs with the mass flow rate as measured by a weigh truck. In this trial, all techniques offered potential but none produced results close to the accuracy goal. A weighing technique, known as the ‘weigh pad’, offered the most potential for improvement and potential to accurately measure the mass flow rate with a single calibration under all conditions. The weigh pad technique suffered from very small load cell sensitivity to flow rate, drift in baseline readings and susceptibility to mechanical noise/acceleration dynamics.An opportunity arose to install a complete yield mapping system on a harvester within a commercial operation. This opportunity was accepted to assess the potential for applying yield maps to the agronomic management of sugar cane. Because the weigh pad sensor required further development at this stage, chopper and elevator power were used as a measure of mass flow rate. A full yield mapping system was developed. Yield mapping, directed soil sampling and variable rate gypsum application was conducted on a case study field. Economic analysis shows a clear economic benefit when compared with standardmanagement.Analysis is conducted on the weigh pad sensor examining its susceptibility to mechanical noise/acceleration dynamics. Theory is developed to mathematically model the effects of acceleration dynamics on the accuracy of weigh pad sensor. Laboratory bench testing supported the mathematical model. From the theoretical and experimental analysis a number of conclusions are drawn:· The weigh pad should be made as light as possible to minimise the error due todynamic conditions.· Electronic analogue filters should be used to reduce the noise due to externalacceleration.· The weigh pad should be as rigid as possible to maximise its natural frequency.A new weigh pad sensor was designed based on these conclusions. Field trials indicated the effects of external accelerations dynamics were significantly reduced. Baseline drift was then found as the next major factor limiting accuracy. The baseline drift was principally caused by the secondary extractor fan of the harvester inducing a negative pressure on the weighpad. A rubber curtain placed between the weigh pad and the secondary extractor fan reduced the negative force on the weigh pad due to the secondary extractor fan by 74% (from 17 N to 4.4 N). Therefore it is recommended the curtain be used to minimise the impact of the secondary extractor fan on the baseline drift of the weigh pad.A yield mapping system has been developed for the sugar cane chopper harvester incorporating the weigh pad sensor, a ground speed sensor, a DGPS receiver, a yielddisplay/monitor and data logger. Three identical systems have been constructed and installed on three harvesters for the 1998 cane harvest season. The results show sugar cane could be yield mapped using standard yield mapping principles.The level of accuracy being achieved by the yield mapping system is less than 16% error, with 95% confidence, over a measurement area of approximately 1400 m2. Although theaccuracy achieved is not to the desired research goal, yield maps were produced with satisfactory detail to make agronomic management decisions. The reliability of the sugar cane yield mapping system under field condition in a commercial operation was satisfactory. However, two techniques are proposed (“auto-zeroing” and “batch weighing” techniques) to improve the accuracy and reliability of the weigh pad readings during wet or adverseharvesting conditions.After note: At the time of writing the NCEA along with Case Austoft (CNH) were continuing to conduct research and development on the system and are intending to make theyield mapping system available as a standard item on new harvesters and a retrofit unit on existing harvesters in the near future (C. Barret, per. comm. 2001). The proposed “autozeroing” and “batch weighing” techniques are being tested.

Energy harvesting from the surrounding environment has become a hot topic in research as an alternative powering solution. The concept deals with scavenging, as well as, harvesting energy from the surrounding energy sources. Harvesting vibrations, through Micro-Power Generators (MPGs) , has drawn a lot of attention recently due to the reduction in the power requirement of the current sensors and integrated ciruits, and the abundance of ambient vibrations in many environments. Vibration Micro-Power generators (VMPGs) use one of three transduction mechanisms: piezoelectric, electromagnetic or electrostatic. Although electrostatic MPGs are the most compatible mechanism with ICs technology, many challenges face their optimal operation including low efficiency due to power electronics switching losses, the need for pre-charge, and the inability to operate in vibration environments with low frequencies and amplitudes. The objective of this thesis is to develop novel electrostatic micro-power generators using switchless architecture to achieve low cost, small footprint, self-sustained and optimal power generation in different vibration environments including low frequencies and amplitudes. The first electrostatic MPG uses an out-of-plane capacitive transducer. The new generator is sensitive enough to extract output power at very low base excitations. It is designed to use ready-made electret as a charging source and is therefore portable and self-sustained. Moreover, the new MPG can be configured as a wideband MPG in its impact mode of operation. A bandwidth of up to 9 Hz has been realized in this mode of operation. An improved version of the MPG is also presented that produces almost 1mW output power at a base excitation amplitude and frequency of 0.08g (RMS) and 86 Hz. Two nonlinear models developed for the free-flight and impact modes of operation of the MPG are presented to allow future analysis and optimization of the system. The second electrostatic MPG uses a novel interdigitated in-plane parallel plate electrostatic transducer. The new implementation can achieve 78% more output power than the original cited implementation. The MPG is fabricated using MEMS surface micromachining. The MPG introduces a new beam suspension system in which the source voltage is unlimited by the pull-in instability and low MPG center frequency can be realized. The MPG uses charged silicon nitride as a charging source. The MPG produces 65 mV at a base acceleration amplitude and frequency of 2g and 1.1 kHz. The prototype achieves 27% less resonance frequency with only one eight the size of the previous implementation. A third electrostatic MPG architecture is introduced. The new architecture eliminates the need for restoring force elements (springs) in the MPG. The architecture can realize arbitrarily low MPG center frequency. It is suitable for both rectilinear and cylindrical structures and can be used with different vibration energy transduction methods. A prototype is fabricated and tested to demonstrate the feasibility of this architecture. The center frequency of the prototype is found to be 2 Hz demonstrating low frequency operation. The nonlinear behavior of switchless (continuous) electrostatic MPGs is further studied for optimal power operation. A consistent approximate analytical solution is developed to describe the nonlinear behavior of switchless comb-finger electrostatic MPGs. The method of multiple scales is used to develop such model. The model was found to be valid for MPGs operating under tight electromechanical coupling conditions and for moderately-large base excitations.

Energy harvesting from the surrounding environment has become a hot topic in research as an alternative powering solution. The concept deals with scavenging, as well as, harvesting energy from the surrounding energy sources. Harvesting vibrations, through Micro-Power Generators (MPGs) , has drawn a lot of attention recently due to the reduction in the power requirement of the current sensors and integrated ciruits, and the abundance of ambient vibrations in many environments. Vibration Micro-Power generators (VMPGs) use one of three transduction mechanisms: piezoelectric, electromagnetic or electrostatic. Although electrostatic MPGs are the most compatible mechanism with ICs technology, many challenges face their optimal operation including low efficiency due to power electronics switching losses, the need for pre-charge, and the inability to operate in vibration environments with low frequencies and amplitudes. The objective of this thesis is to develop novel electrostatic micro-power generators using switchless architecture to achieve low cost, small footprint, self-sustained and optimal power generation in different vibration environments including low frequencies and amplitudes. The first electrostatic MPG uses an out-of-plane capacitive transducer. The new generator is sensitive enough to extract output power at very low base excitations. It is designed to use ready-made electret as a charging source and is therefore portable and self-sustained. Moreover, the new MPG can be configured as a wideband MPG in its impact mode of operation. A bandwidth of up to 9 Hz has been realized in this mode of operation. An improved version of the MPG is also presented that produces almost 1mW output power at a base excitation amplitude and frequency of 0.08g (RMS) and 86 Hz. Two nonlinear models developed for the free-flight and impact modes of operation of the MPG are presented to allow future analysis and optimization of the system. The second electrostatic MPG uses a novel interdigitated in-plane parallel plate electrostatic transducer. The new implementation can achieve 78% more output power than the original cited implementation. The MPG is fabricated using MEMS surface micromachining. The MPG introduces a new beam suspension system in which the source voltage is unlimited by the pull-in instability and low MPG center frequency can be realized. The MPG uses charged silicon nitride as a charging source. The MPG produces 65 mV at a base acceleration amplitude and frequency of 2g and 1.1 kHz. The prototype achieves 27% less resonance frequency with only one eight the size of the previous implementation. A third electrostatic MPG architecture is introduced. The new architecture eliminates the need for restoring force elements (springs) in the MPG. The architecture can realize arbitrarily low MPG center frequency. It is suitable for both rectilinear and cylindrical structures and can be used with different vibration energy transduction methods. A prototype is fabricated and tested to demonstrate the feasibility of this architecture. The center frequency of the prototype is found to be 2 Hz demonstrating low frequency operation. The nonlinear behavior of switchless (continuous) electrostatic MPGs is further studied for optimal power operation. A consistent approximate analytical solution is developed to describe the nonlinear behavior of switchless comb-finger electrostatic MPGs. The method of multiple scales is used to develop such model. The model was found to be valid for MPGs operating under tight electromechanical coupling conditions and for moderately-large base excitations.