Hydropower is an early and well-developed form of electricity generation in New Zealand, as well the most important form of electricity generation globally. This paper analyses the world's energy structure, along with New Zealand's energy structure, the distribution of existing hydroelectric power plants, hydroelectric power operators, the distribution of hydroelectric grids, types of hydroelectric power stations and types of hydro turbines. Furthermore, it also compares the hydropower development in New Zealand relative to other nations, such as China and Norway. New Zealand's power plants: hydro, geothermal and wind farms, are compared in terms of environmental impact, investment benefits, levelized generation costs, Māori culture and generation technology. Because countries worldwide are acting towards the 2050 carbon neutral, the use of electric vehicles is gradually increasing. Finally, Therefore, a surge in electricity generation, and its usage, is anticipated. To overcome this issue, upgrading and expanding existing hydropower plants or building small hydropower is considered to be one of the best options for New Zealand to fulfill the electricity demand and commitment towards low carbon emission.

The restructuring of the energy industry is imperative, as New Zealand strives to reduce greenhouse gas emissions. New Zealand has abundant renewable energy resources, and about 85% of current electricity generation is from renewable energy sources. However, in recent years, it appears that a considerable fraction of wind energy has been underutilized. This article reviews the history, current status, and future trends of wind energy development in New Zealand. The main challenges to the current development of wind energy are summarized compared to other countries. The main challenges come from the bi-cultural influence, environmental influence, and economic and social influence due to the variable nature of wind power, it is critical to store and operate power safely and reliably during peak power generation periods. This article compares seven mainstream wind energy storage technologies and analyzes the best solution for wind energy storage in New Zealand. This article analyzes the feasibility of using small-scale household (standard power rating range from 0.004 to 16 kW) wind turbines in New Zealand cities regarding their construction and operation process. The life cycle and the maximum capacity coefficient of such small-scale wind turbines are overviewed via three case studies and later compared with large commercial wind turbines (standard power rating ranges from 1 to 3 MW) in power generation capacity. It has been found that small-scale household wind turbines have notable power generation potential and economic benefits in the long term.

Phase Doppler measurement devices have established themselves as an alternative to laser diffraction-based measurements for recording spray drop size distributions. In addition, phase Doppler devices also provide droplet velocities and volume flux. One limitation of the phase Doppler systems that is not discussed often in the literature is their sensitivity to the amplification voltage used on the photo-multiplier tube (PMT) detector. The correct value of voltage to use depends on the spray density, and so a calibration must be made for each spray by mechanically measuring the flux at a point in the spray. Phase Doppler output parameters (drop sizes, velocities, validation rate, and derived parameters) were measured as a function of voltage in a fixed location in a water spray. The measurements of volume median diameter were not as sensitive to the voltage setting as the volume flux measurements, which may be why the issue of voltage sensitivity is not discussed much in the literature. The contributions of the current work are: for the first time, measurements of sensitivity of DV05 and LWC to PMT voltage settings in PDI are reported, as well as the details of the different validation parameters instead of only the overall validation rate.

Standard methods for measuring pesticide deposition include water sensitive paper and fibre (paper or cord) collectors, which require time consuming manual steps to gather, process and interpret results. Measurement of pesticide deposition is important in evaluating the efficacy of a spray, which affects the total crop yield. A lack of knowledge about spray quality often results in the need to spray to excess, which can contaminate the soil and damage neighbouring ecosystems and the atmosphere. The suitability of PHYTOS 31 capacitive leaf wetness sensors (Meter Group, Pullman, WA, USA) for spray sensing applications was analysed. The best fit calibration function for droplets of similar to 1 mu L volume was linear (R-2 = 0.985). The best fit calibration function for drops > 10 mu L was a weighted sum of a linear and power function (R-2 = 0.984). Thus, the calibration function should be chosen according to the anticipated size of droplet. The PHYTOS 31 sensors and water sensitive papers were used in a field test, comparing electrostatically charged and uncharged sprays. Both measurement techniques show that charged spray is more effective in covering parts of the plants which do not have a direct line of sight to the nozzle. The techniques disagree on quantitative coverage measurement, with the water sensitive papers reporting areal coverage two to four times higher than the capacitive sensors. High-speed video observations show that this is due to contraction (de-wetting) of the drop on the capacitive sensors. The surface of the capacitive sensors is more hydrophobic than the papers. The hydrophobicity of the capacitive sensors appears to be a better match to plant leaves than that of the papers. Capacitive sensors are a suitable measurement tool for evaluating liquid coverage in the field, but further calibration is necessary to be confident in the quantitative data.

This paper describes the organization of student teams in engineering courses developed over several years of the author’s experience at multiple institutions. Students are assigned into groups of 3-4 students each for working on the homework. Homework problems are selected from a source other than the assigned textbook, since it has been found that as many as one-third of the students have access to the solution manual. All students in a group receive the same grade on the homework, and only turn in one copy of the assignment for the group. In order to help insure the full participation of all members of the group, on the day the homework is due, a quiz is given in class, in which one of the problems from the homework is randomly selected for the quiz problem, without any change to the problem. Selection of the students on teams follows best practices of grouping students from under-represented groups together. After that, students are grouped based on common interests gleaned from a survey given on the first day of class. In the group projects students are allowed to set their own responsibilities within the team. Typically one person will be in charge of the team budget, one person will conduct experimental testing, one person will be responsible for numerical modeling, etc. For the group projects each team is given an allocation of “Monopoly Money” that they use for purchasing supplies and paying for faculty and staff time to help them on their projects. At the end of the semester group project students give an evaluation of the performance of their teammates. Surveys were also given to students to assess the effectiveness of the team homework in helping them learn the material relative to working alone.

The objective of this research project is to eliminate the spray drift caused by crosswind. Spray drift is an important problem for the agricultural industry. Some herbicides (e.g. Dicamba) can cause serious damage if it drifts to nearby crops that are not genetically modified to withstand those herbicides. Our hypothesis is that the nozzle geometry and the injection angle can be actively/passively controlled to compensate for the crosswind velocity and effectively deliver the herbicides to the target area. The measurements include the breakup regime transitions, the droplet sizes, and the droplets trajectory as function of the wind speed and the injection angle. The current results show that the crosswind modifies the primary breakup mechanism from sheet breakup regime (i.e. thinning and fragmentation of the liquid sheet into ligaments) to bag breakup regime (i.e. the formation bags along the downstream side of liquid sheet) resulting in smaller drop sizes and an increased drift flux. Techniques to eliminate the bag breakup regime are presented.

For more than 20 years, air-induction or air-inclusion (AI) nozzles have had increased use for pesticide application due to their drift reduction capabilities. The pressure drop created by the pre-orifice and the venturi chamber results in a slower-moving liquid sheet exiting the main orifice, which in turn results in larger droplet sizes, which are less prone to drift. However, two additional factors somewhat mitigate the advantage of larger droplets from AI nozzles: the lower initial spray jet momentum from AI nozzles (compared to standard nozzles of the same flow rating at the same pressure) means that droplets from AI nozzles are more affected by lateral crosswind, and the lower effective liquid density of droplets from AI nozzles due to the presence of air inclusions means that AI droplets are more affected by aerodynamic drag than pure liquid droplets of comparable sizes from standard nozzles. In this work, theoretical and numerical models are developed to quantify these effects and develop tools for accurate drift prediction from sprayers using AI nozzles. The reduction in spray density due to the presence of air inclusions is in the range of 12% to 36%. This reduction in density affects the aerodynamic drift of the spray droplets, with the result that a droplet with 30% air inclusions would have the drift characteristics of a normal droplet with 20% smaller diameter. Highlights Sprays from air induction (AI) nozzles typically contain 12% to 36% air inclusions by volume. A droplet with 30% air inclusions would have the same drift characteristics as a water droplet of 20% smaller diameter. An analytical model is developed to predict the drift distances of small droplets. Keywords: Air induction, Droplet size, Nozzles, Pesticides, Sprayers.

Kiwifruit are sprayed in late winter with hydrogen cyanamide to enhance with bud burst. The trellis layout of kiwifruit vines in combination with the canopy dormancy at that time of year means that a higher portion of the spray is able to drift away from the canopy. A spray application field study was conducted in a kiwifruit orchard to investigate spray drift potential, with particular focus for conditions relevant to hydrogen cyanamide applications. Spray application with conventional airblast-sprayer hollow-cone nozzles/adjuvant was compared with air-induction (AI) nozzles/drift-reducing adjuvant. Spray was applied every second row in the orchard with spray drift sampling conducted by measuring vertical distribution of spray deposition on both sides of the downwind shelterbelt. The trial showed that airborne drift carried to a height of at least 15 m to the downwind edge of the orchard, which was the height of the vertical sampling towers. The air-induction nozzle/drift-reducing adjuvant system reduced the drift intercepted at 15 m height on the downwind side of the shelterbelt by approximately 78% compared to the standard nozzle/adjuvant system.

The chargeability of liquid sprays is an important factor in determining the deposition efficiency of electrostatic pesticide sprays. The Rayleigh limit provides information on the maximum amount of charge a spray droplet can carry as a function of droplet size and liquid properties. This article reviews the literature to determine what fraction of the Rayleigh limit is achievable. Typically, less than 10% of the Rayleigh limit charge is obtained. The droplet charge per unit mass decreases with increasing droplet size and liquid flow rate. A correlation equation is derived from published data to predict spray droplet charge per unit mass from droplet size, flow rate, and charging voltage.

For a deeper understanding of grapevine trunk disease (GTD) in New Zealand, a cheap, rapid, sensitive method for identifying within-vine microbial communities is required. Wood tissue from grapevine trunks was collected and three different DNA extraction methods were compared: a cetyltrimethylammonium bromide (CTAB) method; the Geneaid Plant Genomic DNA Mini Kit; and the Qiagen DNeasy Plant Mini Kit. DNA samples from the CTAB and Geneaid methods were used for MiSeq DNA metabarcoding targeting the ribosomal internal transcribed spacer 1 (ITS1) region. DNA produced by the CTAB method was of a greater quantity and quality than for the other two methods, although the majority of the DNA samples provided polymerase chain reaction (PCR) amplification of fungal DNA sequences. Fungal metabarcoding profiles from the CTAB and Geneaid samples indicated the presence of fungi normally associated with GTD in New Zealand. The CTAB method was chosen for subsequent work due to its low-cost, simplicity and effective detection of typical GTD fungi. The complete process of sampling through to metabarcoding is now used annually as part of a wider ecological study, screening more than 600 vines at 12 Marlborough vineyards.

In pesticide application, the lack of a suitable theoretical atomization model for flat-fan spray nozzles forces a reliance on empirical data and correlations, even for computational simulations. There is considerable difficulty in the theoretical analysis of the liquid sheet emanating from flat-fan nozzles because no simplification to a two-dimensional analysis can be employed, as is done for cylindrical jets. Nonetheless, 50 years ago, Dombrowski and co-workers used linear stability analysis to analyze the breakup of flat-fan spray sheets into ligaments and from ligaments to droplets. Their correlations have not found use because they include parameters that are difficult, if not impossible, to measure. In this work, the Dombrowski model is simplified using dimensional analysis, resulting in a correlation to predict the volume median diameter of flat-fan sprays in terms of common user parameters, i.e., the nozzle size and operating pressure.

The discharge coefficient (Cd) is a measure of how much of the pressure energy of a nozzle is converted into kinetic energy. With the discharge coefficient known, the exit velocity of the liquid sheet from the nozzle can be calculated from the pressure. It is important to be able to accurately calculate this nozzle exit velocity for use in initializing computational simulations such as AGDISP or CFD. The objective of this work was to measure the discharge coefficients for different types of flat-fan nozzles. In this work, a phase-Doppler interferometer was used to measure the exit velocity for standard, pre-orifice, and air-induction flat-fan nozzles, for rated sizes from 01 to 06, at pressures from 1 to 6 bar. From these velocities, discharge coefficients were calculated. The standard flat-fan nozzles had the highest discharge coefficients, while the air-induction nozzles had the lowest discharge coefficients. For a fixed type of nozzle design, the discharge coefficient increased slightly with the rated flow rate. The discharge coefficient decreased slightly with increasing pressure for a given nozzle. Much of the differences in droplet size for different types of nozzles can be explained by atomization theory as a result of the differences in discharge coefficients for the different nozzle designs.

This study focuses on the development of an autoignition model for diesel sprays that is applicable to phenomenological multi-zone combustion models. These models typically use a single-step Arrhenius expression to represent the low-temperature chemistry leading up to autoignition. There has been a substantial amount of work done in the area of n-heptane autoignition in homogeneous mixtures. Reduced kinetic mechanisms with ten reactions or less have been proposed in the literature to represent the complex low-temperature oxidation of n-heptane. These kinetic models are attractive for multi-zone simulations because of the low number of reactions involved. However, these kinetic mechanisms and the multi-zone treatment of the fuel spray do not account for the effect of turbulence/chemistry interactions on the chemical reaction rate. In this work a correlation has been developed for the total ignition delay time that is a combination of the homogenous ignition delay and dissipation effects. The homogeneous ignition delay is predicted from a chemical reaction mechanism for n-heptane, and the dissipation effects are captured through a phenomenological expression for a characteristic scalar dissipation rate. The characteristic scalar dissipation rate includes effects of injection pressure, ambient density, and injector hole size. The characteristic scalar dissipation rate is compared to a critical scalar dissipation rate to assess the additional delay due to turbulence/chemistry interactions. The autoignition model was implemented into a multi-zone spray model and validated against constant volume ignition delay measurements of diesel sprays.

Standards based grading is a formal assessment mechanism that tests for student achievement of specified learning objectives, or standards. Standards-Based-Grading has been gaining in popularity in K-12 education, and also has been seeing increased use in higher education, though it has only recently been used in engineering education. This paper describes how Standards-Based Grading was implemented in a second-semester Thermodynamics course. A total of eleven learning objectives were specified for the course. In this implementation of Standards-Based Grading, all assessments are done on a pass-fail basis. That is to say, there is no partial credit given. Once a student passes an assessment, usually given in the form of a quiz, on a given learning objective, it is assumed the student has mastered that concept and is not tested on it again. Students are allowed to re-test on particular objectives if they do not pass them on the first try. The final exam serves as a last chance for students to pass any objectives they did not complete earlier in the semester. The learning objectives can be mapped to student outcomes such as those required for accreditation without having to generate a separate set of data outside the normal course grading.

It is essential to know the movement of droplets in time and space (i.e. flux) when measuring and/or predicting spray drift in agricultural application. A study was performed to assess the flux measurements of a phase Doppler system against a standard monofilament system in a wind tunnel. The primary objectives of the study were to compare flux from a new phase Doppler system against 1.7 mm cotton and 2.0 mm nylon strings at varying wind speeds (1.4, 4.2, 8.3, 12.5, and 16.7 m · s−1) and spray exposures times (5, 10, 15, 30, and 60 s) with an overarching hypothesis that the active, phase Doppler is able to accurately measure the flux regardless of exposure and spray mass whereas the static string samplers are limited to a maximum retention. The phase Doppler did measure linearly as expected, however strings did not reach a point in which they loss mass; conversely, they appeared to overload with saturation. These findings are believed to be among many variables which influence the variability of previous mass balance studies.

The quantification of spray mass has historically been accomplished by means of fluorescent dyes and various string and ground samplers to capture the dye-laden spray. However, these methods are typically not used in close proximity to orchard sprayers and are prone to many sources of error. The objective of this study was to assess the ability of an in-field phase Doppler (pD) interferometer to quantify spray mass against two common string samplers. Measurements were taken at 0.5 m increments to 4.5 m vertically and 1.0 m increments to 5.0 m downwind from the spray. Converted flux measurements from the strings were compared with those obtained using the pD interferometer. The current pD technology was found to be incapable of collecting equivalent flux data to that obtained from the strings. However, the pD equipment did provide useful data on droplet velocity and size.

Abstract. The movement of droplets in time and space (i.e. flux) is essential to know when measuring and/or predicted spray drift via agricultural application. A study was performed to assess the flux measurements of a phase Doppler system against the standard string derived flux in a wind tunnel. The primary objective of the study was to compare flux from a new phase Doppler system against 1.7 mm cotton and 2.0 mm nylon strings at varying wind speeds (5, 15, 30, 45, and 60 km/h) and spray exposures times (5, 10, 15, 30, and 60 s) with an overarching hypothesis that the active, phase Doppler would be able to accurately measure the flux regardless of exposure and spray mass whereas the static string samplers will be limited to an undefined maximum retention. The phase Doppler did measure as linearly as expected, however strings did not reach a point in which they loss mass; conversely, they appear to be overloading. These findings are believed to be among many variables which influence the high variance of past mass balance works reported in the literature.

The mass balance of orchard air-blast sprayers has historically been assessed using an array of samplers to capture airborne particles. However, these methods only provide an idea of flux with no other information which is pertinent to understand the movement of droplets and their potential to drift While droplet analysis for agricultural sprayers has always been conducted in a laboratory setting with the use of laser devices, a new phase Doppler approach is being explored to assess droplet spectra, velocity, and flux in outdoor field conditions. Therefore it is the objective of this study to develop a methodology and the potential limitations for using a phase Doppler system while in a laboratory setting. Due to the expected variability of field conditions as well as the turbulence of orchard sprayers, a computational approach was sought to assess flux from a single scan of a conical spray plume's diameter. Using a constant scanning speed of 0.0079 m/s, a disc core (D1/DC33) hollow cone nozzle was examined at 310, 410, and 520 kPa pressure at five different heights (10, 20, 30, 40, and 50 cm). Computational flux was then compared to the actual flow rate, finding a 33% average error with a range of 16.9% and 4.7% illustrating a small underestimation of mass with the phase Doppler which was related to distance and droplet frequency. Further, comparisons were also assessed including pattern/symmetry, droplet spectra, velocity, and the overall number of samples. The proposed methodology indicates potential for the use of phase Doppler technology for in situ measurements of spray equipment using a conical-type spray nozzle, such as that of the orchard air-blast sprayer. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Standards based grading is a formal assessment mechanism that tests for student achievement of specified learning objectives, or standards. Standards-Based-Grading has been gaining in popularity in K-12 education, and also has been seeing increased use in higher education. With increased pressure from ABET to measure achievement of student outcomes, Standards-Based Grading provides a method to do that within the traditional course setting without having to generate a separate set of data outside the normal course grading. This paper describes how Standards-Based Grading was implemented in a junior-level fluid mechanics course that included both lecture and laboratory components. A total of nine learning objectives were specified for the course. These learning objectives are: calculate fluid thrust forces, calculate aerodynamic forces, solve pipe flow problems, select a pump for a system, select a flowmeter for a system, write a computer program to solve transient fluids problems, write a professional quality lab report, acquire and analyze laboratory data, and be a valuable member of team that successfully completes a project. The learning objectives can be mapped to ABET student outcomes. In this implementation of Standards-Based Grading, all assessments are done on a pass-fail basis. That is to say, there is no partial credit given. Once a student passes an assessment, usually given in the form of a quiz, on a given learning objective, it is assumed the student has mastered that concept and is not tested on it again. Students are allowed to re-test on particular objectives if they do not pass them on the first try. The earlier in the semester. Student achievement of the learning objectives is compared to that in previous semesters where a traditional grading scheme was used, and grade distributions are also compared.

Project teams, a mainstay in industry practice, are being employed in many capstone design courses. This paper examines industry models for teams and their application to a specific capstone design course. Following Katzenbach and Smith's basics of high performing teams, teams are formed based on individuals' skills. The team is made accountable and committed both as a group and as individuals through the structure and format of the course. The course structure is then planned so that teams progress through Tuckman's development stages of forming, storming, norming and performing, during their two semester capstone design project.