Evaluation of agricultural ecosystem services in fallowing land based on farmers' participation and model simulation

Fallowing with green fertilizer can benefit agricultural ecosystem services (AES). Farmers in Taiwan do not implement fallow practices and plant green fertilizer because the current subsidy level (46,000 NT$per ha) is too low to manage fallowing. This paper defines the objective of government agriculture policy or the farmer’s objective as maximization of farm productivity, approximated to the value of social welfare and AES. Farms, which do not follow proper fallowing practices, often have poorly maintained fallow land or left farmland abandoned. This results in negative environmental consequences such as cutworm infestations in abandoned land, which in turn can affect crops in adjacent farmlands. The objectives of this study are twofold. First, it determines the proper fallowing subsidy based on the concept of payment for ecosystem services to entice more farmers to participate in fallowing. Second, it simulates the benefit of planting green manure in fallow land to the supply of AES based on the rate of farmers who are willing to participate in fallow land practices and essential parameters that can affect soil fertility change. The approach involves a series of interviews and a developed empirical model. The value of AES when the rate of farmer participation is 100$perha)istoolowtomanagefallowingThispaperdefinestheobjectiveofgovernmentagriculturepolicyorthefarmer’sobjectiveasmaximizationoffarmproductivityapproximatedtothevalueofsocialwelfareandAESFarmswhichdonotfollowproperfallowingpracticesoftenhavepoorlymaintainedfallowlandorleftfarmlandabandonedThisresultsinnegativeenvironmentalconsequencessuchascutworminfestationsinabandonedlandwhichinturncanaffectcropsinadjacentfarmlandsTheobjectivesofthisstudyaretwofoldFirstitdeterminestheproperfallowingsubsidybasedontheconceptofpaymentforecosystemservicestoenticemorefarmerstoparticipateinfallowingSeconditsimulatesthebenefitofplantinggreenmanureinfallowlandtothesupplyofAESbasedontherateoffarmerswhoarewillingtoparticipateinfallowlandpracticesandessentialparametersthatcanaffectsoilfertilitychangeTheapproachinvolvesaseriesofinterviewsandadevelopedempiricalmodelThevalueofAESwhentherateoffarmerparticipationis100 ) over the value at the current participation rate of 14%. This study further concludes that the appropriate fallowing subsidy has a large positive impact on AES and social welfare (e.g., benefit from food and biofuel supplies) and is seen as a basis of ecological governance for sustainable agro-ecosystems

The roles of contact conformity, temperature and displacement amplitude on the lubricated fretting wear of a steel-on-steel contact

This paper investigates the effect of contact geometry, temperature and displacement amplitude on the fretting behaviour of an aero-turbo oil lubricated cylinder-on-flat contact. To be effective, the lubricant needed both to penetrate the contact and then offer protection. Lubricant penetration into the fretting contact is found to be controlled by two physical parameters, namely (i) the width of the contact that remains covered throughout the fretting test and (ii) the lubricant viscosity. The protection offered by the lubricant (assuming that it has successfully penetrated the contact) is influenced by four physical parameters, namely (i) lubricant viscosity, (ii) traverse velocity, (iii) nominal contact pressure, and (iv) chemical effects. The relationship between the three experimental parameters which were varied in the programme of work (temperature, fretting displacement and cylinder radius) and physical parameters which influence the protection offered by the lubricant film can be competing, and therefore complex wear behaviour is observed. The roles of the various parameters in controlling the wear behaviour are presented in a coherent physical framework

Fretting wear mapping: the influence of contact geometry and frequency on debris formation and ejection for a steel-on-steel pair

This paper examines the influence of contact geometry and oscillation frequency in a steel cylinder-on-steel flat fretting contact, with contact geometry being varied via the cylinder radius. Fretting frequency did not significantly impact the wear behaviour for more-conforming contacts, but did so for less conforming contacts where at high frequency, the wear rate is 50 % of that observed for low frequency fretting. It is proposed that frequency and contact conformity fundamentally control wear behaviour through influence of both the debris type and the retention or ejection of that debris from the contact. The debris type (either oxide or metallic) is influenced by fretting frequency (which controls the interval between asperity contacts), and by contact conformity (which controls the distance that oxygen has to travel to fully penetrate the contact). Debris retention within the contact is promoted by higher fretting frequencies (the associated higher contact temperature promotes debris agglomeration and sintering in the contact) and by higher contact conformity (which acts as a physical barrier to debris egress). Maps are presented which categorize the observed behaviour and outline a phenomenological framework by which the basic physical processes which influence fretting behaviour can be understood

The dependence of wear rate on wear scar size in fretting: the role of debris (third body) expulsion from the contact

The paper ‘The third-body approach: a mechanical view of wear’ by Maurice Godet (Wear, 100 (1984), pp 437–452) was perhaps the first to articulate clearly the key role of the rate of debris expulsion from a fretting contact in controlling the overall rate of wear. Whilst subsequent research over the past four decades has acknowledged this, the issue is generally addressed qualitatively rather than quantitatively. There are many parameters which will affect the rate of debris expulsion from a fretting contact, and amongst them is the physical size of the fretting contact. In this paper, for the first time, a physically-based relationship is proposed between the debris-expulsion limited wear rate and the contact size. This relationship is able to account for differences in wear rates observed in tests conducted with different (and evolving) contact geometries (non-conforming contacts) over a range of durations, thus clearly demonstrating the validity of the approach

Investigation on the plasticity accumulation of Ti-6Al-4V fretting wear by decoupling the effects of wear and surface profile in finite element modelling

A finite-element-based wear modelling methodology and a computational device for decoupling wear effects is presented in this study. The decoupling of wear effects facilitates the capture of plasticity accumulation on a particular wear-scarring profile after a specific number of cycles. It was determined that significant plasticity accumulation due to plastic shakedown was predicted in a partial-slip case, while a saturation of plastic deformation was predicted in a gross-sliding case. It was also predicted that a significant amount of plasticity does not meaningfully contribute to the stress and strain range observed in the contact region. It was assumed that plasticity accumulation contributes towards wear of the material and feeds the stress changes, which indirectly affects fatigue life

Debris development in fretting contacts: debris particles and debris beds

In this study, the formation and destruction of compacted beds of oxidized debris particles are investigated. Fretting tests of steel specimens were conducted, employing a cylinder-on-flat geometry with displacement amplitude being varied. The debris was examined, both in the form of the debris beds and in the form of loose debris; together, these were characterized to better understand the mechanisms of debris bed formation and development throughout the fretting process. XRD was employed to determine the phase makeup of the debris, with SEM imaging and particle size analysis employed to understand the evolution of the debris from nanoparticles into agglomerates and then into sintered bed structures

Role of pair-breaking and phase fluctuations in c-axis tunneling in underdoped Bi2_{2}Sr2_{2}CaCu2_{2}O8+δ_{8+\delta}

The Josephson Plasma Resonance is used to study the c-axis supercurrent in the superconducting state of underdoped Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ with varying degrees of controlled point-like disorder, introduced by high-energy electron irradiation. As disorder is increased, the Josephson Plasma frequency decreases proportionally to the critical temperature. The temperature dependence of the plasma frequency does not depend on the irradiation dose, and is in quantitative agreement with a model for quantum fluctuations of the superconducting phase in the CuO$_{2}$ layers.Comment: 2 pages, submitted to the Proceedings of M2S-HTSC VIII Dresde

A programming and a modelling perspective on the evaluation of Java card implementations

Java Card Technology has provided a huge step forward in programming smart cards: from assembler to using a high level Object Oriented language. However, the authors have found some differences between the current Java Card version (2.1) and main stream Java that may restrict the benefits of using Java achievable in smartcard programming. In particular, efforts towards evaluating Java Card implementations at a high level of assurance may be hampered by the presence of these differences as well as by the complexity of the Java Card VM and API. The goal of the present paper is to detail the differences from a programming and a modelling point of view

Derivation of a wear scar geometry-independent coefficient of friction from fretting loops exhibiting non-Coulomb frictional behaviour

One source of variation of the sliding tractional force in a gross-slip fretting cycle is the geometrical interaction of the developing wear scars on the opposing specimens. An existing model has been developed to include the compliance of the fretting test apparatus. It has thus been demonstrated that through the influence on the tractional force, the geometrical development of the wear scars affects the slip amplitude and the dissipation of frictional energy in each loop. A method to determine a coefficient of friction which is independent of system stiffness and developments in the geometry of the wear scars is proposed

Investigation on the plasticity accumulation of Ti-6Al-4V fretting wear by decoupling the effects of wear and surface profile in finite element modelling

A finite-element-based wear modelling methodology and a computational device for decoupling wear effects is presented in this study. The decoupling of wear effects facilitates the capture of plasticity accumulation on a particular wear-scarring profile after a specific number of cycles. It was determined that significant plasticity accumulation due to plastic shakedown was predicted in a partial-slip case, while a saturation of plastic deformation was predicted in a gross-sliding case. It was also predicted that a significant amount of plasticity does not meaningfully contribute to the stress and strain range observed in the contact region. It was assumed that plasticity accumulation contributes towards wear of the material and feeds the stress changes, which indirectly affects fatigue life