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  • Electronic Resource  (6)
  • Engineering  (4)
  • alley cropping  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Agroforestry for soil and water conservation in the western Himalayan Valley Region of India 1. Runoff, soil and nutrient losses (1997)
    Springer
    Agroforestry systems 39 (1997), S. 175-189 
    Details
    ISSN: 1572-9680
    Keywords: alley cropping ; canopy cover ; vegetative barriers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Erosion losses were investigated in a field experiment, from 90 × 15 m erosion plots at 4% slope in the western Himalayan valley region of India. The plots were planted with Leucaena leucocephala and Eucalyptus hybrid, either as block plantation or in alley farming with maize (Zea mays), Chrysopogon fulvus grass or turmeric (Curcuma longa). The treatments also included contour planting of sole maize, sole Chrysopogon fulvus grass and a clean weeded cultivated fallow. During the nine year study period, the average annual monsoon rainfall was about 1000 mm and it caused 347 mm runoff and 39 Mg ha-1 soil loss per year from fallow plots. The runoff and soil loss were reduced by 27% and 45% by contour cultivation of maize. Contour tree-rows or leucaena hedges reduced the runoff and soil loss by 40% and 48%, respectively, over the maize plot, reducing soil loss to about 12.5 Mg ha-1. This reduction in erosion was primarily due to the barrier effect of tree or hedgerows and micro-terraces formed through sediment deposition along the contour barriers. Such vegetative measures, that are productive while being protective, offer viable alternative for erosion control in areas with gentile slopes of the valley region. High density block plantations of eucalyptus and leucaena almost completely controlled erosional losses and can be recommended for steeper slopes that are vulnerable to heavy erosion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005916713956
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Agroforestry for soil and water conservation in the western Himalayan Valley Region of India 2. Crop and tree production (1997)
    Springer
    Agroforestry systems 39 (1997), S. 191-203 
    Details
    ISSN: 1572-9680
    Keywords: alley cropping ; biomass production ; contour tree rows ; leucaena hedgerows ; land equivalent ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A ten-year-study (1983 to 1992) conducted on nine 15 × 90 m runoff plots at 4% slope compared production efficiency of Leucaena leucocephala and Eucalyptus hybrid based agroforestry as well as monocropping landuse systems in the warm, subhumid climate of the western Himalayan region of India. Treatments for the first sequence were: monocropping systems of leucaena, eucalyptus, Chrysopogon fulvus grass and maize – wheat rotation, and alley cropping systems of grass and crops at 4.5 and 10.5 m alley widths with paired contour tree rows of leucaena and eucalyptus. In the second sequence, alley width increased to 22.5 m in 1989, grass was replaced by turmeric Curcuma longa and paired contour rows of leucaena hedges were introduced in monocropping systems of grain crops and turmeric. Integration of leucaena and eucalyptus trees with crops caused severe reduction of crop yields ranging from 21 to 92% for wheat grain, 59 to 69% for maize grain, 60 to 67% for dry grass and about 50% for turmeric rhizome depending upon the age of trees and alley width. The grain yield of crops stabilized at about 50% reduction with 22.5 m alley width. Total crop biomass (grain + straw) also revealed a similar trend; however, its magnitude of reduction was less severe than for grain. Production of biomass was much lower near the tree rows than in mid alleys. Managing leucaena as contour hedgerows eliminated crop yield reduction in alleys. Performance of grass and turmeric in alleys was not found to be satisfactory. Biomass produced from trees adequately compensated the crop yield reduction. Land equivalent ratios of agroforestry landuses were comparable or even better than monocropping systems indicating suitability of these systems for the western Himalayan valley region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005900229886
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Formulation and solution of the non-linear, damped eigenvalue problem for skeletal systems (1995)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 38 (1995), S. 3071-3085 
    Details
    ISSN: 0029-5981
    Keywords: structural dynamics ; eigenvalue analysis ; nonproportional damping ; Arnoldi method ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper presents and discusses an Arnoldi-based eigensolution technique for evaluating the complex natural frequencies and mode shapes from frequency dependent quadratic eigenproblems associated with vibration analysis of damped structures. The new solution technique is used in conjunction with a mixed finite element modelling procedure which utilizes both the polynomial and frequency dependent displacement fields in formulating the system matrices. This modelling provides the ability to represent a frequency dependent damping matrix in vibration analysis of skeletal systems.The eigensolution methodology presented here is based upon the ability to evaluate a specific set of parametrized curves for the non-linear eigenvalue problem at given values of the parameter. Numerical examples illustrate that this method, used in conjunction with a secant interpolation, accurately evaluates the complex natural frequencies and modes of the quadratic non-linear eigenproblem and verifies that the new eigensolution technique coupled with the mixed finite element modelling procedure is more accurate than the conventional finite element models.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620381805
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A lanczos-based technique for exact vibration analysis of skeletal structures (1993)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 36 (1993), S. 1987-2000 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper presents and discusses a Lanczos-based eigensolution technique for evaluating the natural frequencies and modes from frequency-dependent eigenproblems in structural dynamics. The new solution technique is used in conjunction with a mixed finite element modelling procedure which utilizes both the polynomial and frequency-dependent displacement fields in formulating the system matrices. The method is well suited to the solution of large-scale problems.The new solution methodology presented here is based on the ability to evaluate a specific set of parameterized non-linear eigenvalue curves at given values of the parameter through an implicitly restarted Lanczos technique. Numerical examples illustrate that the implicitly restarted Lanczos method with secant interpolation accurately evaluates the exact natural frequencies and modes of the non-linear eigenproblem and verifies that the new eigensolution technique coupled with the mixed finite element modelling procedure is more accurate than the conventional finite element models. In addition, the eigenvalue technique presented here is shown to be far more computationally efficient on large-scale problems than the determinant search techniques traditionally employed for solving exact vibration problems.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620361203
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    To discussion by D. Kennedy and F. W. Williams on ‘a Lanczos-based technique for exact vibration analysis of skeletal structures’ (1994)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 37 (1994), S. 3199-3201 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620371813
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    APPLICATION OF k-STEP LANCZOS METHOD TO EXTRACT THE INTERIOR EIGENVALUES OF SKELETAL SYSTEMS (1996)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 705-716 
    Details
    ISSN: 0029-5981
    Keywords: free vibration analysis ; eigenvalue problem ; non-linear eigenproblem ; Lanczos method ; finite element method ; interior eigenproblem ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Unlike analyses performed to determine structural response to environmental loadings (i.e., wind or earthquake), where only a few of the lowest natural modes are assumed to participate in the overall response, mechanically induced loadings can excite higher-order modes and require solution of the interior eigenvalue problem. In such applications, care must be taken to ensure that the finite element model of the vibrating structure effectively models the higher-order modal response and that the eigensolver used to extract the natural frequencies does not encounter convergence problems due to the close spacing of the interior eigenvalues. This paper formulates and applies an implicitly restarted Lanczos-based eigensolver for computing the natural frequencies of skeletal systems from the interior of the eigenvalue spectrum. This interior eigenvalue problem is formulated using a finite element method which utilizes both the polynomial- and frequency-dependent shape functions in representing beam deformation; thus, the resulting eigenvalue problem is nonlinear, or eigenvalue dependent. Planar frame examples are given which illustrate the effectiveness of the proposed modelling technique and eigensolver.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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