Row Distance Research Articles

Internal Flow Condition between Front and Rear Rotor of Contra-Rotating Small-Sized Axial Fan at Low Flow Rate

Contra-rotating small-sized fans are used as cooling fans for electric equipment. The internal flow condition between the front and rear rotors of the contra-rotating small-sized fan is not known well especially at the low flow rate. Furthermore, the blade row distance between the front and rear rotors is an important parameter for the contra-rotating small-sized fan and its influence on the internal flow condition is not clarified at the low flow rate. Therefore, the internal flow condition of the contra-rotating small-sized fan at the low flow rate is investigated by the numerical analysis in this research. The numerical analysis results are validated by comparing the fan static pressure curves of the numerical results to the experimental results. The internal flow condition at the low flow rate is clarified using the numerical models of the different blade row distance L = 10 mm and 30 mm. In the present paper, pressure fluctuations phase locked each front and rear rotor’s rotation are shown and the influences of the wake and the potential interference are discussed by the unsteady numerical analysis results at the low flow rate.

Technology gap analysis: effect of pgr on yield of muskmelon in Ambala (Haryana)

The major constraint for low productivity of muskmelon in the Ambala District of Haryana is non-adoption of recommended package of practices and lack of awareness about the improvedmuskmelon cultivation. To replace this old age technology Krishi Vigyan Kendra, Ambala conducted 20 front line demonstrations on plant growth regulator (Etheral) during kharifseason 2015 and 2016. Cultivation practices comprised under FLDs viz. use of plant growth regulator, maintained recommended plant to plant and row to row distances, recommendeddose of organic and inorganic fertilizers and control of diseases and pest. An average yieldof muskmelon in FLDs ranged from 108.75to 112.00q/ha whereas in local practices 82.05 and 85.00 q/ha during 2015 and 2016, respectively. It was recorded that the percentage increaseyield with high yielding plant growth regulator over local check was recorded in range of 24.55 to 24.10%. Similarly, the extension gap ranged between26.70 to 27.00 q/ha during the years 2015 and2016, respectively.

Effects of multi-orifice configurations of the quench plate on mixing characteristics of the quench zone in an RQL-TVC model

CO2 concentration measurements and Particle Image Velocimetry (PIV) measurements were performed to investigate the effect of multi-orifice plate geometry on mixing characteristics of a rich-burn quick-quench lean-burn trapped vortex combustor (RQL-TVC). The mixing characteristics in the quench zone were discussed in terms of the mixing degree and the mixing uniformity. And the penetration and the residence time of discrete jet flows conducted by multi-orifice plates were analyzed. The diameter (D) and the quantity (n) of orifices in the multi-orifice plate which composed two rows of orifices was varied, but the blockage ratio (BR) remains constant as approximately 81.5%. The distance of the orifice rows (h) equals D corresponding to the orifice in each plate respectively. The location of the first row is not changed, consequently the position of the second row and the orifice relative position ratio of S/D (S presents the spacing between adjacent orifice mid-points) were varied with D. Through measuring the CO2 concentration, the mixing degree and the mixing uniformity in the quench zone are determined. The penetration and residence time of discrete jet flow conducted by multi-orifice quench plates were quantified by PIV measurements. Results show that the quench plate with the smaller number and the larger diameter of orifices has the most momentum and mass corresponding to the longer penetration and residence time, so that this multi-orifice quench plate has the highest unmixedness rate. On the contrary, that with the shortest penetration is not benefit for occurring the full mixing in the quench zone. Therefore, there is an optimization of multi-orifice configuration existing for the design of multi-orifice quench plates which affect the mixing characteristics of the quench zone in RQL-TVC. The mixing progress in the quench zone depends greatly on discrete jet flows, of which the penetration depth falls into the range from 28mm to 48mm. The multi-orifice plate, designated as M6D8.0 with 6 orifices and 8.0mm-diameter, offers the intermediate length of penetration depth (approximately 35mm). The residence time of discrete jet flows derived from PIV results is between 0.6ms and 1.2ms. Most of that is less than 1ms and meets the requirement of the critical time scale of complete quick-mixing.

Modified planting geometry and fertilizer rate on productivity of corn (Zea mays L.) in Vertisols

A field experiment was conducted at Raichur, Karnataka with an objective to find out production potential of grain corn planted in clumps and rate of fertilizer application. Design followed was split plot and repeated thrice with rate of fertilizer application as main factor and planting geometry as sub factor. Treatments consists of planting corn at 2, 3, 4 seeds/hill compared with single seeds/hill (60 cm x 20 cm) and farmers practice uneven spacing. In clumped plants inter row spacing is similar (60 cm) and intra row distance is differ to maintain uniform plant density (83,333 plants/ha) in each treatment. Recommended dose of fertilizers (RDF) was applied in 2 splits and 150% RDF in 3 splits. Results revealed that planting 2 seeds /hill at 60 cm x 40 cm recorded significantly higher yield, economics of corn as compared to 3 and 4 seeds/hill and farmers practice. As increased plant population per hill maintains higher soil moisture at 75 days after planting (7.5-9.4%) and lower dry matter per plant at harvest (236.3 to 185.5 g) as compared to conventional planting. Application of higher (150%) fertilizers in 3 splits recorded higher dry matter production, grain yield, and economic returns over RDF. This may be useful strategy for corn productivity enhancement by clump planting with higher fertilizer rate.

Effect of narrow-row planting patterns on crop competitive and economic advantage in maize–soybean relay strip intercropping system

Narrow-row planting patterns directly affect crop yield and competition in intercropping systems. A two-year (2012 and 2013) field experiment was conducted to determine the interactive behavior between intercrops in a maize–soybean relay strip intercropping system. Maize plants were planted in different narrow-wide row planting patterns, whereas soybean was planted in wide rows. The total biomass and grain yield of maize increased with increasing maize narrow-row spacing, but the opposite trend was observed for soybean. The aggressivity, competitive ratio, and partial relative crowding advantage values for maize were greater than those for soybean. Moreover, the competitive interaction of the intercrops was affected by the distance between maize and soybean rows. The highest intercrop land equivalent ratio (LER) 1.61 and 1.59 was found in the 40:160 planting pattern (i.e. 40 cm narrow-row spacing and 160 cm wide-row spacing of maize) during 2012 and 2013, respectively. Combined with actual yield loss and LER, the intense intra-specific competition of maize plants reduced the depression for the associated soybeans when the maize narrow-row spacing was less than 30 cm. When the narrow-row spacing was wider than 50 cm, soybean growth was seriously depressed by maize because of the stronger inter-specific competition between maize and soybean. The maximum yield and economic advantage appeared in the 40:160 narrow-wide row planting pattern. Therefore, intercropping advantage may be achieved by changing the row spacing and distance between intercrop rows to coordinate the inter-specific competition between maize and soybean.

Density responses and spatial distribution of cotton yield and yield components in jujube (Zizyphus jujube)/cotton (Gossypium hirsutum) agroforestry

Abstract Trees are the dominant species in agroforestry systems, profoundly affecting the performance of understory crops. Proximity to trees is a key factor in crop performance, but rather little information is available on the spatial distribution of yield and yield components of crop species under the influence of trees in agroforestry systems. Also, little information is available on how crop density may be exploited to optimize the yield in such systems. Here we studied the performance of cotton in jujube/cotton agroforestry. Field experiments were conducted in 2012 and 2013 in Hetian, Xinjiang, China. Cotton was grown at a row distance of 60 cm in three densities, 13.5, 18.0 and 22.5 plants m−2 in six m wide paths between tree lines in a jujube plantation. Plant density affected both cotton aboveground dry matter and yield significantly. The highest yield was attained at the intermediate density of 18.0 plants m−2 (20.0 plants m−2 corresponding in sole cotton), lower than the optimal density in sole cotton (25.0 plants m−2). Yield at the lower density was constrained by the low number of bolls per m2 as a direct consequence of the low density, whereas at the high plant density yield was constrained by a lower allocation of assimilates to cotton seed and lint, as a consequence of intraspecific and interspecific competitions. There were strong gradients in yield and yield components in relation to the distance from the tree rows. Leaf area and total dry matter of cotton in rows close to the tree lines were reduced, especially in the rows next to the trees. Moreover, biomass allocation to cotton fruits was reduced in these rows. Competitive influences from the trees on cotton performance extended two rows deep in a six-year old jujube stand, and even three rows deep in a seven-year old stand. Shading effects on cotton yield were compensated by increasing plant density as a result of greater boll numbers per unit ground area. Data from this study help guide the design of optimal plant density of cotton in jujube plantations and give insight in the spatial distribution and dynamics of competitive effects in agroforestry systems in general.

Optimum mechanism for breaking the confounding effects of mixed-level designs

Fractional factorial designs (FFD’s) are no doubt the most widely used designs in the experimental investigations due to their efficient use of experimental runs to study many factors simultaneously. One consequence of using FFD’s is the aliasing of factorial effects. Follow-up experiments may be needed to break the confounding. A simple strategy is to add a foldover of the initial design, the new fraction is called a foldover design. Combining a foldover design with the original design converts a design of resolution r into a combined design of resolution $$r+1$$ . In this paper, we take the centered $$L_2$$ -discrepancy $$({\mathcal {CD}})$$ as the optimality measure to construct the optimal combined design and take asymmetrical factorials with mixed two and three levels, which are most commonly used in practice, as the original designs. New and efficient analytical expressions based on the row distance of the $${\mathcal {CD}}$$ for combined designs are obtained. Based on these new formulations, we present new and efficient lower bounds of the $${\mathcal {CD}}$$ . Using the new formulations and lower bounds as the benchmarks, we may implement a new algorithm for constructing optimal mixed-level combined designs. By this search heuristic, we may obtain mixed-level combined designs with low discrepancy.

Soil quality differences in a row-crop watershed with agroforestry and grass buffers

Agroforestry buffers are believed to enhance soil quality parameters in agricultural landscapes. Soil enzyme activities, water stable aggregates (WSA), soil organic carbon (SOC), and total nitrogen (N) have been identified as good indices of soil quality. The objective of this study was to quantify soil quality differences among agroforestry buffer (AGF), grass waterway (GWW), grass buffer (GB), and row crop (RC) areas and distance from the tree base on corn (Zea mays L.)-soybean (Glycine max L.) watershed. Soil samples from AGF at 0, 30, 60, 90 cm distances from the tree base, and from AGF, GWW, GB, and RC areas were collected from summit, shoulder, and foot-slope landscape positions at the paired watershed study near Novelty, MO. Soil enzyme activity, WSA, soil C, and N were determined and data were analyzed statistically. The highest SOC and N percentages were found in AGF and the lowest in RC. β-Glucosidase activity was not significantly different among AGF, GWW, and RC. β-Glucosaminidase and dehydrogenase activities were significantly lower in RC treatment than all other treatments. Fluorescein diacetate (FDA) hydrolase activity was not significant among all treatments. WSA percentage was significantly higher in GWW and AGF as compared to others. Landscape position was not significantly different for all measured soil quality parameters. β-Glucosidase, β-glucosaminidase activities, WSA, and soil N did not differ significantly with distance from the tree base. SOC and FDA hydrolase activity were significantly lower at the tree base. Results imply that permanent vegetation has improved the soil quality by enhancing soil microbial activity and organic matter accumulation, thereby contribute positively to watershed restoration.

Asymmetric uniform designs based on mixture discrepancy

ABSTRACTEfficient experimental design is crucial in the study of scientific problems. The uniform design is one of the most widely used approaches. The discrepancies have played an important role in quasi-Monte Carlo methods and uniform design. Zhou et al. [17] proposed a new type of discrepancy, mixture discrepancy (), and showed that may be a better uniformity measure than other discrepancies. In this paper, we discuss in depth the as the uniformity measure for asymmetric mixed two and three levels U-type designs. New analytical expression based on row distance and new lower bound of the are given for asymmetric levels designs. Using the new formulation and the new lower bound as the benchmark, we can implement a new version of the fast local search heuristic threshold accepting. By this search heuristic, we can obtain mixed two and three levels U-type designs with low discrepancy.

二重反転形小型軸流ファンの設計流量における動翼先端流れ場

Small-sized axial fan is used as air cooler for electric equipment. But there is strong demand for higher power of fan according to the increase of quantity of heat from electric devices. Therefore, higher rotational speed design is necessary, however it causes the deterioration of efficiency and increases the noise. Contra-rotating axial fan is smaller than conventional axial fan under the same rotational speed, and is effective for lower rotational speed design under the same diameter. So, the adoption of contra-rotating rotor for small-sized axial fan was proposed for the improvement performance. In the present paper, the unsteady numerical analysis was conducted to investigate the performance and flow field in contra-rotating small-sized axial fan rotors at the design flow rates. Further, the ideal blade row distance of the contra-rotating small-sized axial fan was clarified with the unsteady numerical analysis results.

Identification of plant configurations maximizing radiation capture in relay strip cotton using a functional–structural plant model

One of the key decisions in crop production is the choice of row distance and plant density. The choice of these planting pattern parameters is especially challenging in heterogeneous systems, such as systems containing alternating strips. Here we use functional–structural plant modelling to address the problem of identifying optimal row distances and plant density in a heterogeneous crop system. We compare radiation capture in sole cotton and relay strip cotton, remaining after harvest of wheat from a wheat–cotton relay strip intercrop. We compare light interception in the two systems under different scenarios of row distance and plant density. Light interception calculations with the functional–structural plant model were evaluated using field observations. Light interception by cotton was mainly determined by row distances and to a lesser extent by plant density. Light interception was reduced by the gaps between the strips in strip cotton. Plant density (per unit area of the whole system) providing maximum light interception was lower in relay strip cotton than in normal cotton. Plastic responses of cotton to canopy heterogeneity, accounted for in the model, did not result in full radiation capture in strip cotton. The gaps between the rows in strip cotton allowed light penetration to deeper canopy layers relevant for the reduction of fruit abortion rate. We conclude that relay strip cotton cannot attain the same light interception as sole cotton, due to the gaps between the strips. Increasing plant density was insufficient to bridge the gap. Thus, the maximum light interception in strip cotton is lower than in sole cotton, and is achieved at a lower overall plant density. FSP modelling provided a suitable tool to identify row distance and plant densities providing high light interception in a heterogeneous canopy.

Effect of planting density on the performance of boro rice (BRRI dhan28)

A field experiment was conducted at the Agrotechnology Field Laboratory of Khulna University during the boro season to evaluate the effect of planting density on the performance of rice variety BRRI dhan28. The experiment received twelve treatments, which were divided into two distinct patterns - single row and paired row. The single row had four treatments and paired row had eight treatments. Planting densities were 40, 27, 20 and 16 hills m-2. The experiment was arranged in a randomized complete block design (RCBD) with three replications. Standard management practices were followed in raising crops. Results revealed that closer spacing produced higher yields where 40 hills m-2 produced the most (4.81 t ha-1), which was statistically similar with that of 27 hills m-2. Paired row planting showed better performance than single row planting. Plant height, grains panicle-1, sterile spikelets panicle-1, 1000-grain weight, grain yield were found better in paired row planting. Paired row planting at a spacing of (35 cm + 15 cm) × 10 cm i.e row to row distance is 35 cm & 15 cm and hill to hill distance is 10 cm; found the highest grain yield (4.81 t ha-1) and the lowest yield (2.97 t ha-1) was found in single row using a spacing of 25 cm × 25 cm.Bangladesh Agron. J. 2014, 17(2): 67-76

Bioenergy maize and soil erosion — Risk assessment and erosion control concepts

In the last decade, legislative incentives have led to a significant increase in maize cultivation for the generation of energy from biomass in Germany. The expansion of maize acreage resulted in an increased risk of water erosion due to the low vegetative soil cover after the seeding of the maize and the linear structure and great distance of the maize rows. Soil erosion is considered a major threat to food security and causes damages both on-site and off-site, i.e., to adjacent infrastructures and surface waters. In this study we investigated the effectiveness of six main erosion control concepts in terms of their reduction of damages using the physically based model Erosion-3D. Simulations were carried out based on an agricultural site in Brandenburg, Germany, for three different rainfall events with average recurrence intervals of 2, 20 and 100years. No-tillage and conservation tillage showed the strongest erosion mitigation potential with reduction rates of up to 90 to 100%. Contour buffer strips and vegetated waterways have only very small erosion mitigation effects. Medium erosion reduction rates were simulated for the division of the field into smaller parcels or strips (alternating maize and winter cereal crops). We conclude that no-tillage or conservation tillage is the most recommendable erosion control measure. However, further research needs to be done on the potential of no-tillage and conservation tillage to increase preferential flow paths, their effect on the vertical outflow rate of pesticides and herbicides into groundwater resources and ways to mitigate these adverse effects. Vegetated waterways and contour buffer strips can be combined with other erosion control measures and entail only a minimal reduction in cultivation area. Their installation is relatively low priced, however, additional maintenance costs may be incurred. Noteworthy reduction rates could only be shown for rainfall events with short return periods. The division of the field into winter grain and maize cultivation areas leads to substantial erosion mitigation rates, but has to be seen in context with the reduction of maize cultivation area. The long-term benefits of decreasing maize acreage under specific circumstances might, however, outweigh the reduced benefits of maize production.

Influence of plant spacing on productivity of true potato seed genotypes during nursery raising

To explore the appropriate plant spacing for true potato seed (TPS) in nursery, the present study was mainly conducted at Agriculture Research Institute, Tandojam, Pakistan located at 25.24, 46.00,’N, 68.32, 12.00E during growing year 2009 and 2010. In this study seeds of three different true potato seed genotypes viz., TPS=9802, TPS=9804 and TPS=9805 were tested under three different plant spacing i.e. 2, 4, and 6 cm, respectively. Whereas, row to row distance was kept constant (25 cm). The results obtained from m 2 area showed maximum number of micro tubers (196.1), small tubers (42.15), medium tubers (26.56) and large tubers (7.57) when TPS-9804 was planted with 4 cm plant spacing. The maximum weight of micro tubers (1302 g), small tubers (480.3 g), medium tubers (340 g) and large tubers (468.5 g) were recorded also in TPS-9804 with same spacing. The overall results for tuber yield showed that TPS-9804 genotype planted with plant to plant distance of 4 cm recorded significantly maximum tuber yield (29.46 t ha 1 ) as compared to rest of the genotypes, hence TPS-9804 genotype is recommended for raising of TPS nursery with plant to plant distance of 4 cm.

Effect of the plant density on different maize (Zea mays L.) hybrids yields and leaf area index (LAI) values

We have investigated the plant number reactions of three maize hybrids of various genotypes in a small-plot field experiment. The plant numbers were 50, 70 and 90 thousand ha-1, while the row distances were 45 and 76 cm. The experiment was set on the Látókép Experimental Farm of Centre for Agricultural Sciences of the University of Debrecen in four replications on calcareous chernozem soil.
 The assimilation area and the leaf area index have important role in development of the crop yield. The studied three different genotype maize hybrids reached its maximum leaf area index at flowering. The maximum leaf area index increased linearly with increasing plant density. The season-hybrids reached less yield and leaf area index. According to our experimental results, we have concluded that with the decrease of the row spacing, the yield increased in the average of the hybrids. The studied hybrids reached the maximum yield at 70 and 90 plants ha-1 plant density. We determined the optimal plant number that is the most favourable for the certain hybrid under the given conditions.The higher plant density was favourable at 45 cm row spacing than 76 cm. The hybrids reached the maximum grain yield at 45 cm row spacing between 76 712–84 938 plants ha-1, while the optimum plant density at 76 cm row spacing changed between 61 875–65 876 plants ha-1.
 The leaf area index values between the applied plant density for the flowering period (July 1, 24), we defined a significant differences. In the archived yields were significant differences at the 45 cm row spacing between 50 and 70, 90 thousand ha-1 plant density, while the number for the 76 cm row spacing used did not cause a significant differences in the yield. There were significant differences between the examined hybrids of yields.

Effect of pruning and row distance on some characteristics in karela

Effect of pruning and row distance on some characteristics in karela

Effect of plant density and row spacing on maize (Zea mays L.) grain yield in different crop year

Nowadays the aim of crop production is to realize the highest possible yield per production area unit by the highest possible crop safety. One of the possible ways for this is to increase of plant density or to decrease row spacing. Therefore, the plant number per unit area can be increased and the potential yield loss of individual plants is compensated by the higher plant density. The development of yield amounts of eight different genotypes was investigated in a small-plot field experiment with four replications on a calcareous chernozem soil type at the Látókép Research Site of the University of Debrecen in the crop years 2013 and 2014. Row distances of 45 and 76 cm, just as plant densities of 50 000, 70 000 and 90 000 plants per ha were set. Significant differences were found between the yield amounts of the studied hybrids in both studied crop years, while the effect of plant density on yield amount showed different results. In the crop year of 2013 the hybrids resulted high yields in the treatment with a row distance of 45 cm and plant density of 90 000 plants per ha, however, in 2014 significant yield decrease was found in comparison with the previous year, that can be attributed to the weather conditions in the months April-May and June. Optimal plant densities of hybrids, just as the corresponding expectable yield amounts were determined with quadratic equations. Optimal plant densities of the hybrids were different in the two studied crop years: in 2013, regarding the treatments set with the row distance of 45 cm, increasing plant densities resulted in higher yields, while in 2014, the yield showed decreasing tendency parallel to the increasing plant densities, that is confirmed by the fact that plant densities of 50 000 and 65 000 plants ha-1 proved to be more favourable. Regarding the treatments with a row distance of 76 cm, hybrids obtained their yield maximums by 80 327 plants ha-1 in 2013, while in the vegetation of 2014, by higher plant density (85 845 plants ha-1).

J0520403 二重反転形小型軸流ファンの部分流量における前後段翼列間流れ場

Small-sized axial fan is used as air cooler for electric equipment. But there is strong demand for higher power of fan according to the increase of quantity of heat from electric devices. Therefore, higher rotational speed design is necessary, however it causes the deterioration of efficiency and increases the noise. Contra-rotating axial fan is smaller than conventional axial fan under the same rotational speed, and is effective for lower rotational speed design under the same diameter. So, the adoption of contra-rotating rotor for small-sized axial fan was proposed for the improvement performance. In the present paper, the unsteady numerical analysis was conducted to investigate the performance and flow field in contra-rotating small-sized axial fan rotors at the partial flow rates. Further, the ideal blade row distance of the contra-rotating small-sized axial fan was clarified with the unsteady numerical analysis results.

1612 二重反転形小型軸流ファンの設計流量における前後段翼列間流れ場

Small-sized axial fan is used as air cooler for electric equipment. But there is strong demand for higher power of fan according to the increase of quantity of heat from electric devices. Therefore, higher rotational speed design is necessary, however it causes the deterioration of efficiency and increases the noise. Then, the adoption of contra-rotating rotor for small-sized axial fan was proposed for the improvement performance. In the present paper, the unsteady numerical analysis was conducted to investigate the performance and internal flow of contra-rotating small-sized axial fan rotors at the design flow rates. Further, the appropriate blade row distance of the contra-rotating small-sized axial fan was clarified with the unsteady numerical analysis results.

Vibration Analysis Based on the Mathematical Model of the Air-Suction Device Tillage Seeder Seeding

In order to study air-suction when tillage planter in the field farming, Vibration due to the surface roughness of the resulting excitation tillage effects on seed planter of the device, Derivation of the air-suction device tillage planter seeder vibration characteristics of the mathematical model, Vibration characteristics of the mathematical model derived gas suction device tillage seeder seed planter primarily by structural properties, Forward speed when operating, Seed row distance between the soil surface, Soil roughness and soil sticky decision. Can predict and analyze working condition tillage planter seed quality through the establishment of the vibration characteristics of the mathematical model.