537 research outputs found

    Выбор оптимального рабочего вектора эксплуатируемых систем методами математического программирования

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    The current state of the development of a laser based process chain for manufacturing fused silica optics is presented. In a first step fused silica is ablated with laser radiation to produce the geometry of the optics. A subsequent polishing step reduces the surface roughness and a third step uses micro ablation to remove the last remaining redundant material. Although the process chain is still under development, the ablation of fused silica already reaches ablation rates above 20 mm3/s with a resulting surface roughness of Ra < 5 ?m and the polishing process is able to significantly reduce this roughness

    Can tillage and agronomy be integrated with herbicide application to control resistant weeds?

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    Non-Peer ReviewedThe prevalence of group 2 resistant broadleaved weeds threatens successful lentil production on the Canadian Great Plains. The objective of this study was to develop an integrated weed management strategy combining physical, cultural and chemical weed control methods for lentil producers dealing with group 2 resistant wild mustard. The study was conducted for 3 years between 2011 and 2013 at 2 locations at Saskatoon and Scott, Saskatchewan. It was a randomized two way factorial with weed control method and seeding rate as the main effects. Weed control treatments tested consisted of a control treated with a glyphosate burnoff, saflufenacil (Heat ™) herbicide, rotary hoeing, half rate metribuzin (Sencor ™) herbicide, a fully integrated treatment, and a full herbicide treatment. Three seeding rates representing 1, 2, and 4 times the recommended seeding rate were tested (130, 260, and 520 plants m-2). Increasing seeding rate consistently lowered mustard biomass at both locations. The full herbicide treatment provided the greatest reduction in mustard biomass followed by the integrated treatment. The integrated treatment relied more on increased seeding rate to reduce mustard biomass and produce yield, and at the highest seeding rate it was able to provide equivalent yield to the full herbicide system. The results of this study show that an integrated system utilizing an increased seeding rate can control resistant weeds and maintain yields to a similar level as a strategy that relies only on herbicides for weed control

    Evaluation of harvest aids application timing for lentil dry down

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    Non-Peer ReviewedHarvesting stage is a critical step for lentil producers to maintain high seed yield and good quality. Desiccating lentil with desiccants/harvest aids can dry down lentil evenly and quickly, and control late-growing green weeds, which enhances lentil harvest efficiency and allows early harvesting. Since the harvest aids are applied at a late growth stage, high herbicide residue in seeds may cause commercial issues with marketing lentil. Application timing of harvest aids is critical for producers. Improper application timing may reduce yield and thousand seed weight, but increase herbicide residue in seeds. Therefore, the objective of the harvest aids application timing (% seed moisture) trial was to evaluate the responses of lentil to different herbicide application timings at Saskatoon and Scott, Saskatchewan, over 2 years (2012 and 2013). For this trial, glyphosate (900 g a.e. ha-1), saflufenacil (50 g a.i. ha-1), and the combination of glyphosate plus saflufenacil (900 g a.e. ha-1 and 36 g a.i. ha-1) were applied when seed moisture content was 60%, 50%, 40%, 30% and 20%. Apart from these herbicide treatments, there was also an untreated control, which is desiccated naturally. Significant relationships between evaluated variables and application timing on the basis of seed moisture content were detected. Also, this trial indicated that early application timing (60% application seed moisture) could result in reductions in lentil yield and thousand seed weight. Glyphosate residue in seeds was less than 4 mg kg-1 when glyphosate was applied alone at 30% and 20% average seed moisture. Glyphosate residue decreased when adding saflufenacil to glyphosate. Saflufenacil residue consistently increased with earlier application timing of the harvest aids

    Evaluation of new and existing desiccants in lentil

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    Non-Peer ReviewedGlobally, herbicide resistance has become a major challenge for many producers. In western Canada, many lentil (Lens culinaris L.) producers have great difficulty controlling Group 2 resistant biotypes. Two of these problematic weeds, wild mustard (Sinapis arvensis L.) and kochia (Kochia scoparia), are particularly challenging for lentil growers and can cause extensive yield loss when not adequately controlled. Desiccation is primarily used to dry down lentil for harvest ease and efficiency but can also be used as a late season control for actively growing weeds. The objective of this project is to evaluate the response of wild mustard and kochia to different herbicides, tank mixed with two different rates of glyphosate (450 g a.e. ha-1 and 900 g a.e. ha-1) at Saskatoon and Scott, Saskatchewan over a 2 year period. Desiccation occurred when the lentil seed moisture content was approximately 30%. Preliminary results are under investigation. Evaluation of seed and plant moisture of the treated plots is ongoing, along with an evaluation of the effects of the treatments on viability and vigour of affected weed seeds

    Evaluating the competitive ability of semi-leafless field pea cultivars

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    Non-Peer ReviewedField pea (Pisum sativum L.) is an important grain legume in Western Canada. Growers can, however, be reluctant to include pulse crops in their rotation because they are poor competitors with weeds. Developing more competitive field pea cultivars is important to ameliorate weed competition. The identification of competitive cultivars and the traits conferring competitive ability should lead to the development of more competitive field pea cultivars. The objective of this research was to evaluate the ability of semi-leafless field pea cultivars to suppress and withstand weed competition and to identify traits that may confer competitive ability in field pea. Field experiments were conducted in 2012 at Floral, Saskatchewan and St. Albert, Alberta. Fourteen semi-leafless field pea cultivars with divergent pedigree, vine length, seed size, and market classes were seeded at a target density of 75 plants m-2 under weedy and weed-free conditions. Imidazolinone-tolerant wheat (c.v. CDC Imagine) and canola (c.v. 45H73) were planted as pseudo weeds at a target density of 20 plants m-2 in the weedy plots. Variables measured were leaf area index, plant height, pea biomass, weed biomass, pea yield, and weed seed production. Data were subjected to ANOVA using the mixed model procedure in SAS. There was no cultivar by treatment interaction for pea yield at Floral, so cultivars did not differ under treatments. CDC Dakota produced the greatest pea yield and Reward produced the poorest pea yield. CDC Dakota was among the best for pea biomass production at both sites, compared to CDC Leroy, which was among the worst at both sites. CDC Dakota was also among the best for the low weed seed production at Floral. CDC Mozart, CDC Patrick, and Cutlass were among the best at Floral for ability to withstand competition at Floral. While, CDC Dakota, CDC Meadow, and CDC Patrick were among the best for their ability to compete at Floral. At both sites, no correlations were strong enough to show which traits are conferring competitiveness in semi-leafless field pea cultivars

    Beam profile reflectometry: a new technique for thin film measurements

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    In the manufacture of semiconductor devices, it is of critical importance to know the thickness and material properties of various dielectric and semiconducting thin films. Although there are many techniques for measuring these films, the most commonly used are reflection spectrophotometry [1,2] and ellipsometry [3]. In the former method, the normal- incidence reflectivity is measured as a function of wavelength. The shape of the reflectivity spectrum is then analyzed using the Fresnel equations to determine the thickness of the film. In some cases, the refractive index can also be determined provided that the dispersion of the optical constants are well known. The latter method consists of reflecting a beam of known polarization off the sample surface at an oblique angle. The film thickness, and in some cases the refractive index, can be determined from the change in polarization experienced upon reflection

    Evaluating the competitive ability of semi-leafless field pea cultivars

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    Non-Peer ReviewedField pea (Pisum sativum L.) is an important grain legume in Western Canada. Growers can, however, be reluctant to include pulse crops in their rotation because they are poor competitors with weeds. Developing more competitive field pea cultivars is important to mitigate weed competition. The identification of competitive cultivars and the traits conferring competitive ability should lead to the development of more competitive field pea cultivars. The objective of this research was to evaluate the ability of semi-leafless field pea cultivars to suppress and withstand weed competition and to identify traits that may confer competitive ability in field pea. Field experiments were conducted in 2012 and 2013 at Floral, Saskatchewan, Saskatoon, Saskatchewan and St. Albert, Alberta. Fourteen semi-leafless field pea cultivars were seeded at a target density of 75 plants m-2 under weedy and weed-free conditions. Imidazolinone-tolerant wheat (c.v. CDC Imagine) and canola (c.v. 45H73) were planted as pseudo weeds in the weedy plots. There was no cultivar by treatment interaction for all of the measured variables thus, cultivars did not differ in the presence or absence of weed competition. CDC Dakota produced the greatest pea yield and Reward produced the poorest pea yield at Saskatchewan. CDC Dakota and CDC Striker were among the best for pea biomass production at Saskatchewan, compared to Reward, which was among the worst. CDC Centennial and CDC Mozart were significantly better at Saskatchewan for their ability to withstand competition, while CDC Dakota, CDC Patrick, and CDC Meadow were statistically the best in their ability to compete with the pseudo weeds. At Alberta, CDC Striker and CDC Dakota were statistically best in their ability to compete with the pseudo weeds, versus Cooper and Stratus, who were among the poorest. At both Saskatchewan and Alberta, no correlations were strong enough to show which traits are conferring competitiveness in semi-leafless field pea cultivars
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