Pruning Operations Research Articles

A parametric linear relaxation algorithm for globally solving nonconvex quadratic programming

In this article, we present a parametric linear relaxation algorithm for globally solving the nonconvex quadratic programming (NQP). In this algorithm, a new parametric linearized technique is proposed for generating parametric linear relaxation programming (PLRP) of the NQP, which can be used to determine the lower bound of global minimum value of the NQP. To improve the convergent speed of the proposed algorithm, a pruning operation is employed to compress the investigated region. By subdividing subsequently the initial domain and solving subsequently a series of parametric linear relaxation programming problems over the subdivided domain, the proposed algorithm is convergent to the global minimum of the NQP. Finally, an engineering problem for the design of heat exchanger network and some test examples are used to verify the effectiveness of the proposed algorithm.

Quantitative and qualitative characteristics of biomass derived from pruning Phoenix canariensis hort. ex Chabaud. and Phoenix dactilifera L

The lack of information about quantitative and qualitative characteristics of residual biomass from ornamental species means that these materials are often left out of biomass and bioenergy projects. Biomass derived from annual pruning operations of Phoenix canariensis hort. ex Chabaud. and Phoenix dactilifera L. was quantified and indirect biomass prediction equations for trees of both species were developed. Direct analysis of the gross calorific value (GCV), determination of elemental composition and moisture content were also performed. This allowed further development of indirect GCV prediction models, which are economically attractive and less time consuming in comparison to direct analysis. Mean quantity of dry biomass and mean moisture content per tree were 24.67 kg and 74.82% for Phoenix canariensis hort. ex Chabaud. and 36.13 kg and 71.03% for Phoenix dactilifera L., respectively. Best biomass and GCV prediction models were obtained when several explicative variables were taken into account (R2 = 53, R2 = 65) (R2 = 74, R2 = 93). The comparison of both species indicated that the Phoenix canariensis hort. ex Chabaud. fronds are longer (mean 3.86 m) and heavier (mean 3.35 kg) than those of Phoenix dactilifera L.. Oposite, the quantity of cut fronds per palm is higher in case of Phoenix dactilifera L. (mean 46.75 fronds).

Improved Apriori Algorithm for Mining Association Rules

Association rules are the main technique for data mining. Apriori algorithm is a classical algorithm of association rule mining. Lots of algorithms for mining association rules and their mutations are proposed on basis of Apriori algorithm, but traditional algorithms are not efficient. For the two bottlenecks of frequent itemsets mining: the large multitude of candidate 2- itemsets, the poor efficiency of counting their support. Proposed algorithm reduces one redundant pruning operations of

Biomass allocation of branches and leaves in Phyllostachys heterocycla ‘Pubescens’ under different management modes: allometric scaling analysis

Aims Allometric relationship between branch and leaf is limited by plant ontogeny and affected by environmental conditions,which is not well investigated in giant clone species such as Phyllostachys heterocycla ‘Pubescens'.Our objectives were to study the effects of different management modes(obtruncation and fertilization) on branch and leaf biomass allocations of P.heterocycla ‘Pubescens' and to discuss the effects within canopy.Methods Obtruncation is a particular pruning operation cutting off the top(about 40%–70% canopy) of P.heterocycla ‘Pubescens'.This management methods used in north Zhejiang of China to reduce trees falling from strong wind or heavy snow.A replicated 2 × 2 factorial experiment(obtruncation and fertilization) was established in Zhejiang Province in 2004.In 2010 and 2011,a total of 50 plants were cut down to investigate branch and leaf biomass,as well as leaf area of selected leaves within the canopy.Allometric scaling was applied to analyze the relation of branch and leaf biomass.Important findings Averaged branch and leaf biomass for individual plant were decreased 40.23% and 41.01%,respectively,following obtruncation and increased 20.18% and 30.23%,respectively,following fertilization.Obtruncation severely changed the growth trajectory and resulted in a greater standardized major axis(SMA) slope,which indicated relatively more biomass was allocated to leaves.This was more significant under non-fertilization treatments.When compared to non-fertilization,fertilization significantly decreased SMA slope in unobtruncated trees,which was attributed to relatively larger leaf photosynthetic products partitioning to branches after fertilization.In addition,allocation patterns of branch and leaf biomass at different canopy parts were affected by light availability that was different in different fertilization treatments.Obtruncation changed SMA slope by nearly 50% and 10% for fertilization,which indicated that direct interference(obtruncation) easily changed the grown trajectory and indirect effects(fertilization) were more limited by plant ontogeny.

An Algorithm on Generating Lattice Based on Layered Concept Lattice

Concept lattice is an effective tool for data analysis and rule extraction, a bottleneck factor on impacting the applications of concept lattice is how to generate lattice efficiently. In this paper, an algorithm LCLG on generating lattice in batch processing based on layered concept lattice is developed, this algorithm is based on layered concept lattice, the lattice is generated downward layer by layer through concept nodes and provisional nodes in current layer; the concept nodes are found parent-child relationships upward layer by layer, then the Hasse diagram of inter-layer connection is generated; in the generated process of the lattice nodes in each layer, we do the pruning operations dynamically according to relevant properties, and delete some unnecessary nodes, such that the generating speed is improved greatly; the experimental results demonstrate that the proposed algorithm has good performance. DOI: http://dx.doi.org/10.11591/telkomnika.v11i8.3063

Frequent Itemsets Mining Based on Concept Lattice and Sliding Window

In this paper, a frequent itemsets mining algorithm of data stream based on concept lattice and sliding window is presented. This algorithm mines frequent concepts for new inflowing basic window in batches in a sliding window and generates concept lattice Hasse diagram. With introduction into small support degreeand error factorto do the pruning operations for non-frequent concept node, each connection point in the Hasse diagram contains the information of frequent itemsets and support degree. As the generation of Hasse diagram in the new basic windows, we integrate concept lattice vertically with the generated Hasse diagram and sliding window, and ultimately output all frequent itemsets through scanning all the graph nodes of Hasse diagram graph. The experimental results show that the proposed algorithm has a good performance. DOI: http://dx.doi.org/10.11591/telkomnika.v11i8.3140

Efficient breadth first search on multi-GPU systems

Simple algorithms for the execution of a Breadth First Search on large graphs lead, running on clusters of GPUs, to a situation of load unbalance among threads and un-coalesced memory accesses, resulting in pretty low performances. To obtain a significant improvement on a single GPU and to scale by using multiple GPUs, we resort to a suitable combination of operations to rearrange data before processing them. We propose a novel technique for mapping threads to data that achieves a perfect load balance by leveraging prefix-sum and binary search operations. To reduce the communication overhead, we perform a pruning operation on the set of edges that needs to be exchanged at each BFS level. The result is an algorithm that exploits at its best the parallelism available on a single GPU and minimizes communication among GPUs. We show that a cluster of GPUs can efficiently perform a distributed BFS on graphs with billions of nodes.

Estimation of pruned biomass form dendrometric parameters on urban forests: Case study of Sophora japonica

Abstract The amount of residual biomass from pruning operations of urban trees is a potentially abundant, and an underutilized source that could contribute significantly more to regional and national bio-economies than it does at present. Better utilization of woody biomass from urban green space, leisure and industrial areas could offer bio-based fuels for heat and power generation, reduce pressure on forests and reduce the management costs on a local and regional level. The aim of the work was to quantify woody biomass proceeding from pruning operations and verify the potential of using allometric relationships developed for urban forests. Quantitative results of the residual wood biomass obtained from annual pruning operations of Sophora japonica are presented in the paper according to the type of pruning practice applied. Wood formed 59.97% of total weight of all pruned material before the drying process, wood moisture content in wet basis was 44.88% and mean quantity of dry biomass (branches without leaves) obtained per tree was 18.07 kg. Regression models were applied to predict weight of dry biomass obtained per tree. Significant relationship was observed between quantity of biomass and diameter at breast height at R2 = 0.60. The analysis indicates that an abundant amount of residual biomass originating from pruning operations of ornamental species can be used to achieve ecological and energy targets. Moreover, the presented methodology creates a tool for better prediction of income, field work and logistics management for the future.

Temporal stability of within-field patterns of NDVI in non irrigated Mediterranean vineyards

<p style="text-align: justify;"><strong>Aims</strong>: The objective of this paper is to study the temporal stability of withinfield spatial variability of the Normalised Difference Vegetative Index (NDVI) at two time scales: intra-annual and inter-annual. This study aims to provide answers to the practical use of NDVI and, in particular, to determine whether it is possible (i) to advance the date of image acquisition in order to increase the time required for image analysis and interpretation before harvest and (ii) to verify if an image acquired in one year can be used to manage the vineyard in the following years.</p><p style="text-align: justify;"><strong>Methods and results</strong>: The study was conducted on 17 individual fields. The analysis of the intra-annual stability was performed with four images in 2007 and two images in 2006 that were acquired at different stages of vine development. The analysis of the inter-annual stability was performed with five images taken around veraison on five different years over a period of 10 years (from 1999 to 2009). For the 17 fields of the study, a sampling grid was defined to take into account the characteristics of image processing and the particular shape of each field. A rank coefficient of correlation (Spearman) was used to characterize the correlation between dates of acquisition (images). A Kendall test was implemented to individually characterize and identify the source of the observed temporal stability.</p><p style="text-align: justify;"><strong>Conclusion</strong>: In Mediterranean conditions, this study highlighted the temporal stability of within-field NDVI patterns both within a season or between seasons. Regarding the intra-annual scale, an image acquired from 15 to 20 days before veraison had a significant correlation (p < 0.05) with an image acquired at harvest. For earlier images (i.e., taken around flowering), the strength of the correlation decreased as the time lag between two images increased. This decrease was probably linked to summer pruning operations, the presence of an inter-row cover crop or a spring vigour that differed from the final vigour in some fields. Regarding the inter-annual scale, images acquired at veraison were all significantly correlated (p < 0.05) over the 10 year period regardless of the time lag between image acquisition. The degree of the correlation decreases continuously with time. For the 17 fields of the experiment, a decrease in the stability of NDVI between years was noticeable when significant changes in vine training (irrigation, replanting) occurred. For fields that did not undergo major changes, the spatial patterns of NDVI could be considered relatively stable over time for periods up to 3 to 5 years according to the age of the vineyard.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: This study showed that in Mediterranean conditions it is possible (i) to advance the date of image acquisition to at least 20 days before veraison if the objective is to highlight the spatial variability at harvest, (ii) to use information from an image acquired at veraison over several subsequent years if the field does not undergo major changes in management practices and (iii) to use earlyseason images (around flowering) as a potential source of information for managing other operations.</p>

Assessment of the effect of Nectria flute canker on wood quality within mature Pinus radiata using multiple methods

Nectria flute canker is a fungal disease that results in cankers on Pinus radiata stems. The disease, caused by the pathogen Neonectria fuckeliana, is associated with commercial pruning operations that limit knot defect to a central core to promote growth of high-quality clearwood. Nectria flute canker is present in commercial plantation forests in parts of New Zealand and Chile. Symptoms of the disease, bark cracks, stem flattenings or depressions and flute cankers, were identified on 25 mature Pinus radiata trees. Trees were felled, and discs crosscut from within, and adjacent to, the disease symptoms. The discs were photographed, and three different methods were used to determine the extent of Nectria damage beyond the defect core into the valuable clearwood sheath. These methods included a visual assessment of photographs of internal damage and two quantitative methods, based on calculations of defect extent using image processing software. Overall, flute cankers were associated with the greatest degree of encased bark and severe decay pockets, and stem flattenings the least. None of the flattened stems had internal decay. The average damage to the clearwood sheath due to flute canker was 43%, whilst that for bark cracks and flattenings was 19 and 8%, respectively. Similar results were achieved using all three methods, and the preferred method would depend on the context of the study. Using a combination of all three methods provides a robust method for measuring the damage to internal wood quality by stem pathogens and other abiotic agents.

A Comparison of Disinfectants to Prevent Spread of Potyviruses in Greenhouse Tomato Production

Potyviruses, transmitted by a diverse array of common aphid species, infect a broad range of vegetable crops, and can be problematic in greenhouse tomato production. Once introduced, these viruses are believed to be transmitted plant-to-plant during pruning operations, and can infect large sections of a greenhouse, resulting in significant losses in fruit quality and yield. Several methods are used for virus management in greenhouse production, including rouging of diseased plants and treatment of tools and facilities with virucides to eradicate the virus responsible. To clarify potyvirus transmission efficiency from an infected source during pruning operations, experiments were conducted using direct and serial mechanical inoculation of Potato virus Y (PVY) using a scalpel dipped in a suspension of PVY-infected plant sap. Tests demonstrated that both serial and direct inoculation resulted in significant PVY transmission, but that transmission rates declined after the first few plants in serial transmission. Additional tests evaluated the efficiency of two virucides, a quaternary ammonium solution and sodium hypochlorite, for virus inactivation during pruning operations using a range of concentrations and time points. Results demonstrated that 0.5% sodium hypochlorite treatment for two seconds was sufficient for virus control, and superior to treatment with quaternary ammonium solutions. Accepted for publication 20 December 2010. Published 21 February 2011.

Traditional and innovative summer pruning techniques for vineyard management

This review paper highlights physiological and vine performance effects of widely adopted summer pruning operations such as leaf removal, shoot trimming and positioning and cluster thinning. Leaf removal is addressed either under its traditional configuration, i.e. removing in dense canopies some or all leaves around clusters usually pre-veraison to improve fruit microclimate and facilitate spraying and early (pre-flowering) defoliation primarily aimed at inducing looser clusters via a concurrent reduction of fruit-set and berry size. Time consuming and still non mechanisable cluster thinning is evaluated primarily in terms of response variability vs. season and intensity with emphasis on lack of significant reduction of final yield per vine in thinned treatments when large crop compensation occurs. Variability of expected final grape composition improvements in thinned vines is also discussed based on the actual vine balance when the operation is performed. Although fully mechanisable, shoot trimming is still a debated choice in terms of timing and severity. While severe (i.e. fewer than six or seven main leaves retained) and late (i.e. several weeks after bloom) cuts should possibly be avoided, the effects of shoot trimming on final grape composition is discussed as a function of seasonal changes in leaf area development, demography, fraction of lateral leaves from the total and leaf to fruit ratio. It is indicated that, for vertically shoot-positioned trellises, if the support trellising is correctly designed and vine vigour is balanced, timing and severity of trimming are dictated by the vine “itself” rather than by grower choices. Overall, this review underscores the importance of leading the vineyard to a “natural” control of vegetative growth, which would minimise the need for an extensive use of summer pruning. In other words, such vineyard operations should be viewed not just as something the growers “have to do”, instead as specific tools used to achieve targeted final grape composition.

Detemination of the time of pruning regarding the ability of developing flower buds and their frost tolerance in sweet cherry varieties

In sweet cherry growing, intense technology is introduced as the up to date development. Among the elements of the technology are the choice of variety, planting design and pruning are the main elements. The methods, intensity and the timing of pruning are largely dependent from the growing habits of the varieties, the light demand of the parts of different age and their tendency of getting bald on the aging zones. One of the main limiting factors of production, the frost damages are outstanding. In choosing the site of plantation, we must avoid the places, where spring frosts used to occur, the next moment is the role of the variety and the technology applied. In Hungary, the late or spring frosts are considered, however, the winter frosts may also cause heavy losses, which depend also on the health and nutritional condition of the trees when being exposed to temperature minima. Our present study is based on a 9-year-old plantation trained to slender spindle as well as to free spindle crown. We observed the development of fruiting structures and their frost damage also in relation with the timing of the pruning operations during the winter or summer, and compared also the varieties with each other.

Flower production of apple varieties grown by different environmental technologies

The flower production of four apple varieties have been observed grown in integrated and in ecological growing technologies during the spring of 2010. The trees produced in the last year (2009) nearly similar yields, so the effect of the technologies may causen differences in the production of flowers. According to our results, the ecological technology produced higher flower densities in the majority of variables, which was in relation with the vigor, branching and thickening of the trunks. The varieties observed displayed substantial differences in the appearance of fruiting structures of different age on the branches. This information may prove to be essential for the decisions to be made in timing and severity at the pruning operations.

Growth of Newly Established Tilia platyphyllos ‘Rubra’ Roadside Trees in Response to Weed Control and Pruning

This tree establishment study investigates the effect of weed control and pruning treatments on stem and branch diameter increment of newly planted broad-leaved lime (Tilia platyphyllos ‘Rubra’) roadside trees. Weed control significantly increased stem circumference four years after establishment by 3.6 cm (1.4 in) from 24.5 cm (9.7 in, untreated control) to 28.1 cm (11.1 in). In terms of Danish nursery sales prices, this corresponds to an increase of tree cash value of 1201 DKK (160.90 €, 235.40 US$) per tree. Calculating with 400 DKK (53.60 €, 78.40 US$) as cost for contract weeding per hour, this corresponds to 0.75 hours per tree per year for a period of four years. In addition to weed control treatments, trees were pruned at establishment, two years after establishment, or at both times. None of the pruning treatments affected stem diameter growth, but branch diameter and branch:stem diameter ratio were significantly reduced by all pruning treatments. Branch diameter ranged from 40.1 mm (1.6 in) on unpruned trees to 34.6 mm (1.4 in on trees pruned both times. Branch:stem diameter ratio ranged from 0.54 on unpruned trees to 0.49 on trees pruned both times. In consequence, weed control is recommended as a strong management practice. Mild pruning is also considered advisable, if structural crown problems can be avoided at an early stage, and if the tree has to be prepared for later pruning operations.

Analysis of the process of biomass harvesting with collecting-chippers fed by pick up headers in plantations of olive trees

The resources used in the collection of residual biomass, originating from the pruning operations of olive trees, by means of chippers fed by pick up headers were determined. The chippers were evaluated for the harvesting of the ligneous materials aligned between the crop lines. The resources employed were measured as labour hour per hectare, machine hours per hectare and fuel consumption. This quantification permits the economic analysis based on knowing the prices of these resources in a particular moment. The results show that manual alignment takes 5 h ha −1 , the chipper takes 1.6 h of machinery ha −1 and 4.8 h of man h ha −1 . The fuel consumption is 4.75 l of gas–oil h ha −1 , obtaining 1.98 t of dried biomass per hectare.

GIS Application to Define Biomass Collection Points as Sources for Linear Programming of Delivery Networks

Much bio-energy can be obtained from wood pruning operations in forests and fruit orchards. Several spatial studies have been carried out for biomass surveys, and many linear programming models have been developed to model the logistics of bio-energy chains. These models can assist in determining the best alternatives for bio-energy chains. Most of these models use network structures built up from nodes with one or more depots, with arcs connecting the depots. Each depot is a source of a certain biomass type. Nodes can also be biomass storage points or production facilities (e.g., power plants) where biomass is used. The arcs in the networks represent transport between depots. In order to combine GIS spatial studies with linear programming models, it is necessary to build a network from a digital map of biomass production centers, such as orchards. Biomass collection points should therefore be defined as sources in the delivery network model. In this work, a mathematical calculation method is developed to select the actual biomass collection points on a map. The database for this model is composed of area surveys of forest and agricultural biomass storage points given in GIS maps (shape files). The limits of the area studied and different types of biomass are defined and located in different layers of the GIS maps. These energy-biomass production maps are overlaid with a 1 km × 1 km grid of the area studied. The result is a grid in which the different types of total available biomass in each quadrant are known. Harvesting and collection costs are also defined. The connections between all n × m quadrants of the area studied are defined by the available road network. Every quadrant is associated with a point on the road network. The selection criteria for sources of biomass (sub-areas) are the following: firstly, a minimum production of available biomass type is required; and secondly, harvesting and collection costs should be minimal. The algorithm provides the location of points where biomass from the associated area can be concentrated. These biomass collection points are then taken as source nodes in the network during the implementation of the logistics models. In the next step, the network is analyzed by linear programming techniques to supply the optimal position of energy plants or factories, given the available biomass sources.

Post-establishment vegetation control in two pine saw-timber stands in South Africa

In pine plantations, the effect of shading following canopy closure reduces the growth of competing vegetation. In some pine stands, particularly those grown for saw-timber, full canopy closure is not achieved due to a combination of the low initial planting density, pruning and thinning. This means that the important competitive characteristic of complete shading is lost, resulting in stands with the potential to support competitive levels of post-establishment vegetation. At the time of the first pruning operation, two trials were established, one on a 4.5-year-old P. patula and one on a 2.9-year-old P. tecunumanii stand to determine the competitive effect of post-establishment vegetation on tree growth. Besides a weedfree and weedy treatment, the selective control of either the herbaceous vegetation (grasses and annual broadleaved plants) or all the perennial woody broadleaved plants was carried out in either the woody or herbaceous treatments. Only the woody perennial broadleaved plants were removed prior to any pruning event in the commercial weed control treatment (operational). These treatments were maintained until the trees were thinned (over nine successive growing seasons) with tree performance monitored over this period. There was no significant tree growth or survival response to competition from post-establishment vegetation for the duration of the trial.

Using hybrid models to develop silvicultural prescriptions for Eucalyptus nitens

A structural model was developed for Eucalyptus nitens from relationships between leaf area and stand structural components, and was incorporated into an existing hybrid model. The existing hybrid model combines the process-based site productivity model P roM od and an empirical stand growth model N itG ro. The modified hybrid model was used to predict the development of stand leaf area and stand crown length in 17 diverse stands of E. nitens in Tasmania. We demonstrate how the model can be used to identify sites for pruning based on site productivity, predicted leaf area index, and minimum piece sizes required at the end of the rotation; schedule pruning operations based on height to the base of the green crown and leaf area index, and schedule thinning to minimise height-related windthrow risk.

A pilot study into the effects of fertilizer applied at planting on branching inPinus patula

SYNOPSIS This study aimed to investigate the effect of fertilizer applications on the early branching dynamics of trees that were fertilized with 25 g P tree.1 at planting compared to unfertilized trees. The study took place at two sites where significant positive growth responses to the nutrient additions had been found immediately after planting. The branching was assessed at the time of the first pruning operation. The results of the study indicated that the application of fertilizer does not change the branching morphology of the trees in terms of branch length, number of branches per whorl, number of whorls per pruned length of stem or branch diameter (the latter measured at the point where the branch joins the stem). However, significant differences were found in the diameter over the stubs (DOS). Differences between the DOS in the fertilized and unfertilized trees was much greater towards the bottom of the stem. The maximum DOS within the pruned length of stem, which provides an indication of the extent of the knotty core, was significantly higher in the fertilized trees and greater than the target set by the saw timber industry in the area. Thus it appears that the greater initial volumes are being achieved in the fertilized stands at the expense of wood quality. The results indicate the importance of site-specific pruning regimes which take the initial growth rates of the trees into account, particularly if these growth rates are influenced by other silvicultural operations.