Spacing Uniformity Research Articles

Field Slope Effects on Uniformity of Corn Seed Spacing for Three Precision Planter Metering Systems

The effects of field slope on planter seed spacing uniformity were evaluated for three different seed metering units (cell plate, finger pick-up, and flat plate) operating with medium round corn seed in a laboratory using the University of Nebraska planter test stand with an opto-electronic seed spacing sensor system. The metering units included a John Deere MaxEmerge Plus VacuMeter row unit with the standard cell corn plate, a John Deere MaxEmerge Plus VacuMeter row unit with the flat plate, and a John Deere MaxEmerge Plus row unit with the finger pick-up metering system. Planter seed spacing uniformity was measured using three parameters: ISO Miss index, ISO Multiples index, and Coefficient of Precision (CP3). Six replications for nine field slope treatments were conducted for each metering unit. The field slope treatments included: front-up (front of planter unit), front-down, right-up (right side of planter unit), and left-up each at field slope levels of 10% and 20%, and level.

Optical frequency comb generation from a monolithic microresonator

Optical frequency combs provide equidistant frequency markers in the infrared, visible and ultraviolet, and can be used to link an unknown optical frequency to a radio or microwave frequency reference. Since their inception, frequency combs have triggered substantial advances in optical frequency metrology and precision measurements and in applications such as broadband laser-based gas sensing and molecular fingerprinting. Early work generated frequency combs by intra-cavity phase modulation; subsequently, frequency combs have been generated using the comb-like mode structure of mode-locked lasers, whose repetition rate and carrier envelope phase can be stabilized. Here we report a substantially different approach to comb generation, in which equally spaced frequency markers are produced by the interaction between a continuous-wave pump laser of a known frequency with the modes of a monolithic ultra-high-Q microresonator via the Kerr nonlinearity. The intrinsically broadband nature of parametric gain makes it possible to generate discrete comb modes over a 500-nm-wide span (approximately 70 THz) around 1,550 nm without relying on any external spectral broadening. Optical-heterodyne-based measurements reveal that cascaded parametric interactions give rise to an optical frequency comb, overcoming passive cavity dispersion. The uniformity of the mode spacing has been verified to within a relative experimental precision of 7.3 x 10(-18). In contrast to femtosecond mode-locked lasers, this work represents a step towards a monolithic optical frequency comb generator, allowing considerable reduction in size, complexity and power consumption. Moreover, the approach can operate at previously unattainable repetition rates, exceeding 100 GHz, which are useful in applications where access to individual comb modes is required, such as optical waveform synthesis, high capacity telecommunications or astrophysical spectrometer calibration.

Optimisation of the seed spacing uniformity performance of a vacuum-type precision seeder using response surface methodology

The objective of this study was to optimise the seed spacing uniformity performance of a precision seeder using response surface methodology (RSM) and to verify the optimum levels of the variables. The variables considered in the study consisted of the vacuum on the seed plate, the diameter of seed holes and the peripheral speed of the seed plate. Cotton seeds were used for sowing and experiments conducted in this study were based on the central composite design (CCD), one of the designs in RSM. Data obtained in the laboratory were divided into three different groups in order to obtain values of the multiple index, quality of feed index and miss index. An additional performance criterion was also proposed and used as an indicator of the sowing performance. This was the root-mean-square deviation from the theoretical seed spacing. The data obtained in the laboratory were then used to develop functions in polynomial form that allowed the calculation of the optimum level of each independent variable considered in the study. The optimum levels of vacuum pressure and the diameter of holes for precision seeding of cotton seeds were found to be around 5.5 kPa and 3 mm, respectively. No optimum value was obtained for the peripheral speed of the seed plate. It was found that the lower the peripheral speed of the plate, the higher is the performance.

Resolving the resolution of array CGH

Many recent technologies have been designed to supplant conventional metaphase CGH technology with the goal of refining the description of segmental copy number status throughout the genome. However, the emergence of new technologies has led to confusion as to how to describe adequately the capabilities of each array platform. The design of a CGH array can incorporate a uniform or a highly variable element distribution. This can lead to bias in the reporting of average or median resolutions, making it difficult to provide a fair comparison of platforms. In this report, we propose a new definition of resolution for array CGH technology, termed “functional resolution,” that incorporates the uniformity of element spacing on the array, as well as the sensitivity of each platform to single-copy alterations. Calculation of these metrics is automated through the development of a Java-based application, “ResCalc,” which is applicable to any array CGH platform.

Heat treatment application to increase fruit and vegetable quality

Abstract Purpose of review: Heat treatment has been used for quarantine and decay co ntrol in an increasing variety of crops, and its use has been extended to the inhibition of the ripening processes or the induction of resistance to chilling injury. Through a brief ov erview of certain studies about the physiological, pathological and physical principles of heat treatment with emphasis on the physical o r engi-neering aspects, an effort is made to determine the focus of further research. Main findings: Research effort on heat treatment in the postharvest stage has been increasing steadily in recent years, with successful laboratory investigations and some scale-up development of the us e of hot water, radio frequencie s, microwaves and hot air in d isinfes-tation, disinfection, chilling injury control and the slowing down of the ripening process in various fresh horticultural crops. Several aspects of the mechanisms of heat treatment in terms of decay control, induction of thermotolerance, and heat transfer under un iform heating media have been thoroughly evaluated. The threshold te mperature and uniformity in space throughout the entire duration of the process are the two most important factors that should be take n into account during heat treatment process development on an in dus-trial scale. Directions for future research: The challenge for heat treatment lies in the scale-up of some treatment methods by optimising the temperature range and duration, improving the uniformity of heat treatment, and conducting research into a protocol for the ado ption of different heat treatments as part of the postharvest chain. Keywords: none Abbreviations *Correspondence to: Jianbo Lu, McGill University, Mac-donald Campus, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, Quebec, Canada Stewart Postharvest Review 2007, 3: 4 Published online 01 June 2007 doi: 10.2212/spr.2007.3.4 Symbols k Thermal conductivity (W /m °C) h Heat transfer coefficient (W/m °C) r Radial coordinate originating from the fruit centre r

Effects of Various Planters on Emergence and Seed Distribution Uniformity of Sunflower

In this study, four different type seeders were evaluated for seed spacing, depth uniformity, and plant emergence at three forward speeds (3.6, 5.4, and 7.2 km h-1). The planter types were: no-till planter, precision vacuum planter, universal planter, and semi-automatic potato planter. The sowing uniformity of the horizontal distribution of seeds was described by using the multiple index, the miss index, the quality of feed index, and the precision in addition to the means and standard deviations of the sample methods. Uniformity of planting depth of seeds was described using the mean, standard deviation and the coefficient of variation of the sample methods. Plant emergence ratios were evaluated by mean emergence time, emergence rate indexes, and emergence percentage. The best seed spacing uniformity and seed emergence ratio were obtained with the no-till planter, and the best seed depth uniformity was obtained with the precision vacuum planter. Forward speed significantly affected only the mean emergence time (P < 0.05). As forward speed increased, mean emergence time decreased.

Energy Analysis of the Tillage Systems in Second Crop Corn Production

ABSTRACT The aim of this experiment, to examine the energy input and output in the second crop corn production using four different tillage systems for soil preparation: (1) minimum tillage with stubble (MTS), (2) minimum tillage without stubble (MT), (3) conventional tillage with stubble (CTS), and (4) conventional tillage without stubble (CT). Corn was sown as a second crop just after harvest of wheat. Direct and indirect energy inputs consisting of machinery, fertilizers, seeds, irrigations and chemicals were converted into energy units according to their amounts being consumed. The machinery and fuel energy inputs for the tillage operation were reduced 53.7% with MT compared to CTS. The total energy input for producing corn utilizing CTS was 20,608 MJ/ha, compared to 19,102 MJ/ha for producing corn with MT. When the grain yield was taken into account, the energy output/input ratios for MTS, MT, CTS and CT were estimated to be 6.3, 7.6, 6.6 and 7.0, respectively. The tillage systems did not statistically affect uniformity of plant spacing, but statistically affected the yield. The grain yield was the greatest (8,719 kg/ha) in CT compared to the other tillage treatments.

Distribuição longitudinal de sementes de soja e características físicas do solo no plantio direto

As técnicas do plantio direto são complementares às atuais técnicas de conservação do solo, que envolvem menor mobilização e permanência de cobertura vegetal na superfície do solo. O trabalho foi realizado na UNESP - Jaboticabal, de novembro de 2003 a março de 2004, e teve como objetivo avaliar o efeito de culturas, manejos e marchas do trator na semeadura da soja no plantio direto. O delineamento utilizado para instalação do experimento foi em blocos ao acaso, no esquema de parcelas subsubdivididas, com quatro repetições. Foram analisados: estande inicial, distribuição longitudinal de plantas, resistência mecânica à penetração, densidade e teor de água no solo. O estande inicial não foi influenciado pelos tratamentos. A distribuição longitudinal das plantas foi afetada pela marcha do trator. A resistência do solo à penetração sofreu efeito apenas na camada de 0,20 a 0,25 m na interação culturas, manejos e marchas do trator. A interação culturas e manejos na camada de 0,10 a 0,20 m para densidade indicou a presença de resistência maior do que 0 a 0,10 m e de 0,20 a 0,30 m. O teor de água no solo foi menor nas camadas superficiais do solo, influenciado pelos manejos.

Inter- and Intraplant Competition in Corn

While competition for resources within and among plants is understood to affect yield per plant and thus per unit area, direct effects of crop management on plant competition are not always well understood. I narrowly define interplant competition here as a decrease in the amount of light intercepted per plant due to proximity to adjoining plants; such competition may or may not affect corn yield per unit area. Examples of management factors that influence interplant competition include uniformity of plant spacing, timing of plant stand loss, and plant population density. Intraplant competition effects are defined here as factors that affect internal allocation of photosynthate within the plant. I will restrict the discussion to plant damage effects that result in yield loss, and will relate this to reductions in light interception. I conclude that the goal of crop management is to have the corn plant set an adequate number of kernels, then to maximize the interception of light energy during the grainfilling stage in order to maximize yield.

Effect of seed coating on the accuracy of single-seed sowing of sesame under field conditions

Sesame seed treatments consisted of 2 different coatings and uncoated seeds. These were tested to determine their effect on accuracy of plant spacing after emergence in single-seed sowing under different field conditions. Seedbed treatments were composed of traditional tillage without crop residue and conservative tillage with wheat stubble. To quantify plant spacing accuracy and emergence uniformity, spacing between plants within a row and plant emergence per day were measured. The measurements were used to calculate the quality of feed index, multiples index, skip index, precision, emergence rate index, mean emergence date and the percentage of emergence. It was concluded that seed treatments had a significant effect on multiples index and skip index of horizontal distribution pattern and emergence rate index, mean emergence date and the emergence percentage. The coating acted negatively on seed germination and led to missing plants and less plant spacing uniformity in the row. The shortest emergence date and maximum percentage of emergence and quality of feed index were obtained with uncoated sesame seeds. The parameters, except emergence rate index, were not affected statistically by tillage treatments. It was found that all seeds emerged in less time on conservation tillage plots with stubble.

Laboratory measurement of seed drill seed spacing and velocity of fall of seeds using high-speed camera system

Due to the individual volumes of fluted wheel metering systems each holding more than one seed, seed drills provide random seed distribution. A prerequisite for the improvement of seed spacing is the fast and reliable evaluation of distribution accuracy in laboratory tests. A high-speed camera system for evaluating seed spacing uniformity and velocity of fall of seeds is described. The performance of the high-speed camera system in terms of seed spacing evaluation was compared with a sticky belt test stand, used as a reference. Identical seed patterns were evaluated applying both methods simultaneously using wheat and soybean seeds. The speed of the metering rollers of the seed drill was set at 10, 20, 30 and 40 rpm and that of the seed drill at a simulated travelling speed of 1 m/s. In general, the high-speed camera system worked well in obtaining the seed spacing and velocity of fall of seeds. In all the tests with the wheat and soybean seeds, the high-speed camera system did not miss any seed. The sowing uniformity of the seed drill as investigated was affected by the speed of the metering rollers. Coefficient of variation of seed spacing, velocity of fall and coefficient of variation of velocity of fall of seeds decreased as the speed of the metering rollers increased.

A survey of stand establishment and in-row spacing uniformity in Washington potato fields

Missing plants and non-uniform in-row plant spacing can result in economic loss for potato growers. In-row seedpiece and plant spacing uniformity of 70 Washington potato fields was measured, and factors contributing to missing plants investigated from 2000 through 2002. Ninety-one percent of the fields were planted with cut seedpieces, and the remaining 9% were planted with cut seedpieces, and the remaining 9% were planted with whole, uncut seed tubers. Russet-type cultivars were planted in 79% of the fields, and the remaining 21% were planted with red-skinned and yellow- and white-fleshed cultivars. Seedpiece or plant spacing deviated an average of 25% from the intended spacing mean, with a range of 7% to 43%. Coefficients of variation (CV) for grower in-row plant and seedpiece spacing ranged from 18% to 69% compared with a hand-planted check average of 13%. Based on the growers’ intentions, the average plant population of the 70 fields should have been 44,000 plants ha−1, but averaged only 40,600 plants ha−1. On average, 6% of the grower-intended stand was missing because of planter skips, while less than 1% was missing due to seedpiece failure or decay. There were 1,980 clumped seedpieces ha−1 and each clump typically contained two seedpieces. Twenty-one percent of the fields had at least 700 planter-skips ha−1 where three or more consecutive plants were missing. Despite management efforts, planters were typically unable to place seed uniformly at the intended spacing. Improved planter and seed-cutting-operation management along with new planter technology would likely improve Washington potato stands.

Field Study of the Space Uniformity of Meteorological and Wave Parameters in the Coastal Zone. On the Problem of Calibration of a Side-Looking Radar on the Sich-1M Satellite as an Instrument for Measuring Wind Velocity over the Sea

We study the problem of subsatellite calibration of a side-looking radar (SLR) of the Sich-1M satellite regarded as an instrument for the evaluation of the velocity of surface wind and discuss the possibility of application of the meteorological and wave parameters measured from the stationary oceanographic platform of the Experimental Department of the Marine Hydrophysical Institute (Ukrainian Academy of Sciences) for their evaluation in the remote regions of the sea. These regions can be observed with the help of the SLR without errors introduced by the appearance of the coast in elements of space resolution. To prove the indicated possibility experimentally, we perform simultaneous measurements of the water and air temperatures, wind velocity, and the characteristics of waves both from the platform and in the water area neighboring with the platform on the side of the sea at distances of up to 4.8 km. The quantitative estimates of the degree of space uniformity of the analyzed parameters are deduced under the conditions of stable inshore wind. A conclusion is made that the platform can be used for subsatellite measurements aimed at the validation and improvement of the algorithm of reconstruction of the velocity of surface wind by using the SLR of the Sich-1M satellite.

Stand Establishment Responses of Maize to Seedbed Residue, Seed Drill Coulters and Primary Tillage Systems

Plant residues increase the risk of stand establishment for maize. This may result in reduced crop yield and may limit adoption of conservation tillage by farmers. A field study was conducted to compare the effects of two planter attachments (plain/notched coulters), two previous crop residue levels (baled/non-baled) and two tillage systems (mouldboard/chisel ploughs) on secondary surface residue, depth of seed placement, percent emergence, miss index, multiple index, quality of feed index and precision of plants spacing. Results show that the chisel plough followed by a no-coulter planter left crop residue at a quantity three times that for the mouldboard plough, a level suitable for conservation farming. The addition of a coulter assembly reduced the residue level to 30%, a level recommended as minimum for soil conservation. For the mouldboard ploughed plots, the per cent residue retained was almost half the recommended minimum residue level for soil conservation; therefore, a coulter attachment is not recommended to avoid further surface residue reduction. Residue removal resulted in a severe reduction of the surface residue on mouldboard ploughed soils to a level less than that recommended for conservation farming. In general, chisel ploughing resulted in less acceptable values both for plant establishment and indices of planter performance as compared to mouldboard ploughing. Coulter attachment improved the uniformity of plant spacing, the plain coulter performing better. The range of the precision index obtained in this study was 24·6–27·3%, indicating that the planter performance was close to the recommended range for uniform seed placement and satisfactory performance specified in the literature. The study showed that previous crop residue levels did not prove to be effective on the parameters studied. Finally, chisel ploughing followed by a coulter-planter appears to be a good alternative to a more conventional cropping system, offering advantages for conservation farming and better plant establishment; however, more precise maize sowing can be obtained on mouldboard ploughed soils.

A growth pathway for highly ordered quantum dot arrays

To realize the desired zero-dimensional behavior of a quantum dot ensemble, the ability to fabricate quantum dots with a high packing density and a high degree of size, shape, and spacing uniformity is crucial. Here we report highly ordered InAs nanodot arrays grown by molecular-beam epitaxy on nonlithographically nanopatterned GaAs. Approximately 20 billion dots are grown in a 1cm2 area with the smallest size dispersion ever reported and forming a lateral superlattice in hexagonal dense packing form. These techniques presage a pathway to controlled growth of periodic quantum dot superstructures, which offer macroscopic spatial coherence in the interaction of quantum dots with radiation.

Strain-Mediated Uniform Islands in Stacked Ge/Si(001) Layers

The role of a Si spacer layer in improving the uniformity of multilayer coherent Ge quantum dots on Si(001) is investigated using scanning tunneling microscopy. Deposition of the Si spacer layer at room temperature and subsequent annealing lead to the formation of (001)-oriented Si mesas on top of Ge islands (pyramids and huts). One mesa forms when the island beneath is pyramid-like, whereas a few mesas form when the island beneath is an elongated hut. The mesas are found to be preferential nucleation sites for the Ge islands in consecutive stacked layers. The vertical-pyramid-replicating and hut-breaking processes play key roles in the improvement of island size, shape and spacing uniformity.

Thermal equilibrium of a fluid system on Einstein turntable and its space-time duality

The dependence of proper temperature on cylindrical coordinatesT0（ρ）in thermal equilibrium of a fluid system on Einstein turntable is solved by special and general relativity separately. The results show that the contraction of motiontemperature depends only on the speed instead of on the acceleration of subsystems. According to uniformity in space and constancy in time of the coordinate temperature of an equilibrium system, the space-time duality between Einstein turntable and early universe directly presents that the proper temperature of a medium of the early universe is inversely proportional to the spatial scale-factor R(t).

Within‐Row Plant Spacing Variability Does Not Affect Corn Yield

Nonuniform plant spacing within the row in corn (Zea mays L.) may reduce grain yield. To investigate the response of corn to plant spacing variability, experiments were conducted at two locations in south‐central Ontario during 2000 and 2001. Six plant spacing treatments, 6.7 to 16.2 cm in standard deviations (SD), were established by planting Roundup Ready corn with increasing proportions of conventional corn seeds and then removing the conventional corn using glyphosate before three‐leaf stage. Using SD as well as short gap, long gap, double, and cluster as an index of plant spacing variability, effects of plant spacing variability on corn growth and grain yield were investigated. Averaged across locations and years, grain yield was not significantly affected by plant spacing variability. Plant spacing variability also had no significant effect on leaf number, plant height, leaf area index, and harvest index. There were no correlations between plant spacing variability and stalk lodging and barren or double ears. The lack of strong correlations among plant growth, grain yield, and plant spacing variability indicates that spacing uniformity within the range used in this study is not a significant factor in determining grain yield under commercial conditions and common plant densities used in Ontario.

Phase-shifting diffraction-grating interferometer for testing concave mirrors

We present a new concept for a phase-shifting diffraction-grating interferometer, which is intended to test concave mirrors simply using a single reflective diffraction grating and fiber optic confocal microscope focusing optics. Our configuration allows generating a high-quality reference wave from a small active grating area that can be readily fabricated with good homogeneity of grating substrate and uniformity of groove spacing. The test and reference waves encounter no other optical components, so only a small active surface area of the grating affects the test result. The fiber optic confocal microscope design adopted to solve the alignment problem between the grating and the converging wave greatly reduces systematic errors of the interferometer. In addition, the phase-shifting capability provided by translating the grating using a microactuator enables one to attain nanometer accuracy in optical figure metrology.

Time and Space Uniformity of Indoor Bacteria Concentrations in Chicago Area Residences

The objective of this article is to assess spatial and temporal variation of indoor gram-positive bacteria and Staphylococcus sp. in 20 urban residences. At each residence, air was sampled at one outdoor site and four indoor sites (rooms) to assess spatial variation and once each season for five consecutive seasons to assess temporal variation. All temporal and spatial comparisons were performed using data obtained by the Andersen sampling technique. A secondary objective of this study is to evaluate relationships among several sampling methods used to measure bacteria levels; since differences in the measured concentrations are expected, the focus is to discern if corresponding measurements relate to each other. Not surprisingly, comparisons among the four sampling systems revealed statistically significant differences, although levels correlated relatively well. Using data only from the Andersen samplers, we conclude that seasonal variation is residence dependent with typically higher summer levels, but a clear pattern of variation could not be established. Room-to-room difference is not statistically significant, but the basement levels render the basement a distinct microenvironment. Indoor concentrations exceeded corresponding outdoor concentrations 75% of the time. Staphylococcus accounts for approximately 27% of the average indoor bacteria levels. The highest levels of gram-positive bacteria are found in the kitchen. The presence of multiple indoor sources with variable emission rates in multiple indoor locations results in bacteria levels that vary with time and space.