65 research outputs found
Replanting Guidelines for Sugar Beet Production in Southern Minnesota
No full textEstablishing an adequate plant population is one of the first challenges of sugar beet production. Reduced sugar beet emergence results in a decision between a lower than desired plant population or replanting the field. The objective of this study was to determine the plant population that warrants replanting a field to maximize extractable sugar ha-1. The study was conducted in three environments during the 2016 and 2017 growing seasons. Two planting dates and six plant populations were utilized in each environment. The two planting dates were separated by 19 or 20 days to simulate a replant situation. Sugar beets in each planting date were hand thinned to six populations of 44,000, 58,700, 73,400, 88,100, 102,800, and 117,400 plants ha-1. Planting date and plant population did not significantly affect sugar concentration. However, planting date and plant population influenced yield and extractable sugar ha-1. Extractable sugar yield was maximized with the first planting date and populations of 102,800 and 117,400 plants ha-1. A population of 58,700 plants ha-1 in the first planting date had similar extractable sugar yield to the second planting date populations of 88,100, 102,800, and 117,400 plants ha-1. Sugar beet populations above 58,700 plants ha-1 should not be replanted based on the results from this study.This article is published as Mark W. Bloomquist, Andrew W. Lenssen, and Kenneth J. Moore. Replanting Guidelines For Sugar Beet Production In Southern Minnesota. Journal of Sugar Beet Research 56 (2019): 3-20. doi: 10.5274/Jsbr.56.1.3. Posted with permission.</p
Replanting guidelines for sugar beet production in southern Minnesota
No full textEstablishing an adequate plant population is one of the first challenges of sugar beet production. Reduced sugar beet emergence results in a decision between a lower than desired plant population or replanting the field. The objective of this study was to determine the plant population that warrants replanting a field to maximize extractable sugar ha-1. The study was conducted in three environments during the 2016 and 2017 growing seasons. Two planting dates and six plant populations were utilized in each environment. The two planting dates were separated by 19 or 20 days to simulate a replant situation. Sugar beets in each planting date were hand thinned to six populations of 44000, 58700, 73400, 88100, 102800, and 117400 plants ha-1. Planting date and plant population did not significantly affect sugar concentration. However, planting date and plant population influenced yield and extractable sugar ha-1. Extractable sugar yieldwas maximized with the first planting date and populations of 102800 and 117400 plants ha-1. A population of 58700 plants ha-1 in the first planting date had similar extractable sugar yield to the second planting date populations of 88100, 102800, and 117400 plants ha-1. Sugar beet populations above 58700 plants ha-1 should not be replanted based on the results from this study.</p
Genotype by Location Effects on Yield and Seed Nutrient Composition of Common Bean
No full textCommon bean (Phaseolus vulgaris L.) is an important staple food crop in households worldwide. Genotype and location influence phenotypic nutrient composition. However, there are limited data on the magnitude of this variation for common bean yield and nutritive value. The objective of this study was to determine the effect of location on yield and seed nutritional composition. Four globally important varieties (dark red kidney/‘Montcalm’, great northern /‘Taurus’, black /‘Eclipse’ and yellow Mayocoba/‘MY06326’) were planted for two years in four locations (Iowa, Colorado, Michigan, in the USA, and Masaka, Uganda). Yield and seed weight differed among locations and varieties. Yield in Colorado and Michigan was 42% and 56% higher than in Iowa and 76% and 81% greater than in Uganda, respectively. Eclipse had greater yield than Taurus (6%), MY06326 (16%), and Montcalm (35%). Concentration of P, K, Mg, S, and crude protein (CP) differed among varieties. Montcalm had 18%, 7%, and 4% greater P concentration and 13%, 9%, and 5% greater CP than Eclipse, MY06326 and Taurus, respectively. The location × variety interaction was significant only for seed Zn concentration. Despite differences in edaphic factors among locations, elemental concentrations other than Zn were comparatively stable among locations. Stability in seed elemental concentrations across locations and environments is important knowledge for better understanding human nutrition and malnutrition.This article is published as Bulyaba, Rosemary, Donna M. Winham, Andrew W. Lenssen, Kenneth J. Moore, James D. Kelly, Mark A. Brick, Evan M. Wright, and James B. Ogg. "Genotype by Location Effects on Yield and Seed Nutrient Composition of Common Bean." Agronomy 10, no. 3 (2020): 347. doi: 10.3390/agronomy10030347.</p
Electron transport in mesoscopic GaAs / AlGaAs structures with superconducting contacts
No full textApplied Science
't Zit tussen de oren : ontwerp en invulling van operationeel beheersingssysteem voor Stork Technisch Beheer B.V.
No full textDuurzame robotchirurgie
No full textChirurgische robotsystemen winnen aanzienlijk aan populariteit in de medische wereld vanwege hun voordelen op het gebied van precisie, comfort en behendigheid voor de chirurg, wat resulteert in een verbeterd chirurgisch resultaat. Deze voordelen gelden voor ziekenhuizen over de hele wereld, maar zijn niet overal even toegankelijk. Complexe systemen vereisen meer onderhoud, meer training voor gebruik, een aanzienlijke hoeveelheid ruimte, een grote financiële investering en ingewikkelde reinigings- en sterilisatieprocessen. Hierdoor is het integreren van deze robotsystemen toch vaak een uitdaging door de beperkte financiën en infrastructuur in kleinere ziekenhuizen. Dergelijke barricades leiden er vaak toe dat de technologie onbereikbaar wordt in omgevingen die het soms het hardste nodig hebben. De ontwikkeling van goedkope robotsystemen lijkt daarom de sleutel voor minder bedeelde ziekenhuizen om toch toegang te krijgen tot de voordelen die robotchirurgie kent
The design of an active, under-actuated, prosthetic wrist mechanism based on synergetic relations
No full textInspired by work of Montagnani et al. (2015), who found that for prosthetic hands a complex wrist mechanism worked functionally equal to a multi-DOF hand mechanism, new work has been set in motion to extrapolate and test this hypothesis. The goal of this work consisted of building a multi-DOF wrist mechanism, while it was crucial to keep the mechanism small, light, and efficient. A study preliminary to this work has found a single, synergetic relational "path" between all degree of freedom of the human wrist, thereby proving a three dimensional, functional output of orientation by a theoretical mechanism, driven by a single input. This work seeks to design such mechanism, capable of following the proven synergy while remaining small, able, and effective. Starting from scratch, several theoretical mechanism are tested on their ability to create general, non-linear translations. Some of these theories are worked-out into concepts after which a selection is made of the most promising. Further developing these concepts into adequate designs, a set of prototypes, digital and physical, have been used to prove their competence in re-producing the path as found by the preliminary study. Finally, after a fusion of two designs, a final design is developed to a state-of-production. Though the production of a prototype was scheduled, it was not accomplished within the period of this work. This reports finishes with a final design proven theoretically to be successful in re-creating the theoretical synergetic path through a set of compound mechanics. The mechanism thereby proves the mechanical feasibility of the theoretical synergetic path. Though at a greater cost of size and weight, the mechanism is fully able to function as a prosthetic wrist mechanism as required by two individual partner projects. Due the lack of a physical prototype of this final design, testing and result-checks have been limited to a theoretical and digital environment. In the discussion, several options of improvements are given, as well as speculations on a parallel, alternative design course for future work. After outlining a set of important decisions made in this design, an alternative set of decisions is mentioned which are hypothesized to work without some of the sacrifices needed in this design, predominately the volume. Whether this alternative design proves successful, if at all feasible, remains to be attempted. Whether the wrist mechanism has benefited from the synergetic approach remains unanswered as well. Due the lack of physical testing several questions around functionality cannot yet be concluded. After the acknowledgement of this design's drawbacks, and the hypothesis of an improved alternative, no statements on the mechanical benefits of the synergetic approach have been made either. After the mechanism succeeds in proving that the theoretical synergetic relation is physically achievable, it is stated that such (alternative) mechanism without the mentioned drawbacks would, in a mechanical sense, be outstanding
Series Hybrid Electric Aircraft: Comparing the Well-to-Propeller Efficiency With a Conventional Propeller Aircraft
No full textTHE aviation industry is responsible for 12% of the total transportation impact of CO2 while awareness, for decreasing the total carbon footprint, is rising. Both the aerospace and the automotive industry are facing an increasing pressure from society to make the transportation sector more sustainable. Within the automotive industry slowly an increase in electric vehicles can be noticed (<1%). Also in the aerospace industry a rise in electrification can be seen, with small aircraft as the E-Star and E-Fan (two seaters) as commercial examples. Electrification of the transportation sector could further result in a decrease in noise and an increase in lifespan of parts as vibrations are decreased. This master’s thesis is written in conjunction with the chair Flight Performance and Propulsion at the faculty of Aerospace Engineering at the Delft University of Technology. The main purpose is to gain more insight in modelling an (hybrid) electric aircraft and the potential improvements with respect to well-to-propeller efficiency (usefull energy over total energy ratio). This is achieved by first creating a baseline conventional propeller aircraftmodel (ATR72) and then a hybrid electric version of the same aircraft. The variations between the sub-models and validation data are calculated in order to have a feeling for the accuracy of each individual model. Furthermore, both the theoretical and current practical state of technologies are used in the overall model. Finally, a sensitivity analysis is performed to find the driving parameters in the outcome of the model. The analysis of the series hybrid electric aircraft showed first of all that the expected advantages of the concept are ’small to non-existent’. The electric energy used to charge the batteries should first of all come from a renewable source of energy to make the concept feasible. Secondly, the theoretical limits of technology should be approached in order for the well-to-propeller efficiency to exceed that of the conventional ATR72 aircraft (with a maximum of 2%). It is seen that the model converges to an all electric version of the ATR72 if the battery energy density is increased to 2,802 [Wh/kg], this would correspond to the theoretical limit of Lithium Sulphur battery-technology. Furthermore, for an increase in voltage the battery efficiency decreases while all other components will improve in efficiency. The optimum is found in increasing the voltage up to the practical limit of 25 [kV]. Electric propulsion creates new design possibilities as distributed propulsion and variable shaft-speed. Within this thesis it is however shown that the ’benefits’ of distributed propulsion do not outweigh the downsides (increase inweight and decrease in efficiency of all components). Furthermore electric motors allow for temporary torque overloading, by decreasing the rotational speed and increasing the torque, the overall result is an increase in efficiency, which could for example be usefull during the climb or take-off phase. Concluding, the concept of series hybrid electric aircraft is at this moment in time rendered infeasible. The potential within a 35 year time-frame is doubtfull as especially battery technology should improvewith at least 400 [%]. In order to accelerate the transition to hybrid electric or all electric aircraft, the main areas of research should be: battery technology and the integration of alternating current and superconducting materials in rotating machine parts.Aerospace EngineeringFlight Performance and Propulsio
Combined Path Tracking and Stability Control using Model Predictive Control
No full textThis thesis presents a new MPC controller which integrates path tracking and stability control into one controller. Previously these tasks were done by separate controllers, where one controller handled the path tracking while another controller ensured the vehicle was kept in the stable operating region. A drawback of this method is that the controllers have opposing objectives. The path tracker could require a higher steering wheel angle to follow the path, while the Vehicle Stability Controller (VSC) might require a lower angle to keep the vehicle stable. By integrating these two controllers into one controller, the new controller is able to take both tasks into account and optimise the control output such that both objectives are satisfied. This is achieved by implementing two extra yaw rates into the MPC model. These are the expected yaw rates based on the steering wheel angle and lateral acceleration of the vehicle. By comparing these two yaw rates to the actual yaw rate, the stability of the vehicle can be determined. The MPC controller is then able to prioritise path tracking or vehicle stability. This is achieved by actively varying the weights in the cost function depending on the vehicle state. To compare the new MPC controller, 8 benchmark controllers have been created. These controllers can be divided into two groups of four controllers. The first group is able to use differential braking in the control output, while the second group can only output an equal brake torque for all wheels. The benchmark controllers use different methods for path tracking and stability control, to get an understanding of the performance benefits of each method.These different methods include: adding an extra target yaw rate based on path curvature and speed for tracking, adding constraints to ensure vehicle stability and using a separate stability controller to stabilise the vehicle. All controllers are evaluated using the industry standard Moose test as well as a double lane change in simulations. These manoeuvres are used in industry to evaluate stability and can also be used to evaluate path tracking. Furthermore the robustness of the controllers was evaluated by changing various parameters. These variations include: changing vehicle speed, adding extra weight to the vehicle, lowering the road 𝜇 level and performing a lane change where each lane has a different 𝜇 level. The results were evaluated using objective Key Performance Indicators regarding tracking performance and vehicle stability. The results show that the new MPC controller with the combined path tracking and stability control improves performance in both objectives. The new controller improves path tracking by 8% compared to the pure path tracking controller. While the stability is improved by 11% compared to the controller with a separate VSC. Furthermore the new controller was able to keep the vehicle stable at higher speeds and was more robust to varying conditions.Mechanical Engineering | Vehicle Engineerin
Augmenting VSIDS heuristic for the RCPSP/t by initializing activity values using domain-specific information
No full textThe Variable State Independent Decaying Sum (VSIDS) heuristic is one of the most effective variable selection heuristics for Conflict-Driven Clause-Learning (CDCL) SAT solvers. It works by keeping track of the activity values for each variable, which get bumped and decayed based on conflict analysis. These activity values usually start out arbitrarily at zero, which prompts the question if initializing these values can result in better performance.This paper presents several adaptations of the VSIDS heuristic specialized for solving the Resource-Constraint Project Scheduling Problem with time varying resource availabilities and demands (RCPSP/t). The approach uses domain-specific knowledge to initialize the activity values of VSIDS with more relevant values. The experiments presented in this paper show that this domain-specific knowledge can indeed benefit the heuristic and can lead to better solve times, allowing the solver to find solutions for 17% more of the instances and find proven optimal solutions for 5% more instances of the PSPLIB data set.CSE3000 Research ProjectComputer Science and Engineerin
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