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This paper deals with the existence of marginal pricing equilibrium or equilibrium with general pricing rules in an economy with increasing returns to scale or more general types of nonconvexities in production. Its main contribut...
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This paper deals with the existence of marginal pricing equilibrium or equilibrium with general pricing rules in an economy with increasing returns to scale or more general types of nonconvexities in production. Its main contribution is to demonstrate existence of equilibrium with bounded loss and survival assumptions required only on a bounded subset of production allocations. Furthermore, we require only a weakened form of the free-disposal assumption and we also allow nonpositive prices.
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Irregular access patterns are a major problem for today's optimizing compilers. In this paper, a novel approach will be presented that enables transformations that were designed for regular loop structures to be applied to linked ...
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Irregular access patterns are a major problem for today's optimizing compilers. In this paper, a novel approach will be presented that enables transformations that were designed for regular loop structures to be applied to linked list data structures. This is achieved by linearizing access to a linked list, after which further data restructuring can be performed. Two subsequent optimization paths will be considered: annihilation and sublimation, which are driven by the occurring regular and irregular access patterns in the applications. These intermediate codes are amenable to traditional compiler optimizations targeting regular loops. In the case of sublimation, a run-time step is involved which takes the access pattern into account and thus generates a data instance specific optimized code. Both approaches are applied to a sparse matrix multiplication algorithm and an iterative solver: preconditioned conjugate gradient. The resulting transformed code is evaluated using the major compilers for the x86 platform, GCC and the Intel C compiler.
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Presented in this paper is a numerical methodology for the solution of the parabolic governing partial differential equation that describes unsteady advection-diffusion heat transfer. The formulation presented here is shown to be ...
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Presented in this paper is a numerical methodology for the solution of the parabolic governing partial differential equation that describes unsteady advection-diffusion heat transfer. The formulation presented here is shown to be free from the numerical oscillation commonly associated with advection-diffusion heat transfer regardless of the value of the Peclet number. The formulation involves the absorption of the advection term in the unsteady heat equation into the capacitance term. This process is achieved with the use of a control volume methodology applied to each nodal element on a finite-volume mesh. This is shown to ensure that spurious energy losses and gains are avoided and provides for consistency between temperature and energy change. This approach provides unconditional stability and it is shown that good accuracy is achievable with relatively large time-steps.
In order to highlight the features of the approach it is compared against those of benchmark numerical schemes. Detailed analysis is performed for the 1D semi-infinite moving solid problem for which an exact solution is available and for a realistic engineering heat transfer problem. Oscillation free results are achieved at good accuracy for a wide range of Peclet numbers and problems considered.
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about 19%. Analysis of variance of data obtained is carried out at P-value ≤ 0.05. Fabric finished using recipe Ⅰ (Sanitized~R T99-19 alone), recipe Ⅱ (Sanitized~R T99-19 with Siligen~R TX2490) or recipe Ⅲ (Sanitized~R T99-19 ...
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about 19%. Analysis of variance of data obtained is carried out at P-value ≤ 0.05. Fabric finished using recipe Ⅰ (Sanitized~R T99-19 alone), recipe Ⅱ (Sanitized~R T99-19 with Siligen~R TX2490) or recipe Ⅲ (Sanitized~R T99-19 and Siligen~R TX2490 with Arkofix~R NG-ET) manifests inhibition clear zones towards Staphylococcus aureus and Pseudomonas aeruginosa a bacteria, as a result of the physically bound portion of 'dimethyl-tetradecyl-[3(trimethoxysilane-propyl] ammonium chloride (active ingredient of Sanitized~R T99-19) and/or its adduct with Arkofix~R NG-ET' that leaches out of the fabric. However, this portion cannot tolerate repeated laundering up to 10 cycles. Finishing the fabric using Sanitized~R T99-19 at a concentration of 5 g/L can acquire the fabric very high values of reduction in bacterial count'even after 25 washing cycles, regardless of treatment recipe. Below 5 g/L in recipe Ⅲ, the fabric fails to manifest total reduction in bacterial count after 10 washing cycles. Reduction in bacterial count is remarkably improved by increasing the concentration from 5 to 10 g/L in recipe Ⅲ, regardless of washing cycles.
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A mechanism-based constitutive model is presented for the inelastic deformation and fracture of ceramics. The model comprises four essential features: (ⅰ) micro-crack extension rates based on stress-intensity calculations and a c...
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A mechanism-based constitutive model is presented for the inelastic deformation and fracture of ceramics. The model comprises four essential features: (ⅰ) micro-crack extension rates based on stress-intensity calculations and a crack growth law, (ⅱ) the effect of the crack density on the stiffness, inclusive of crack closure, (ⅲ) plasticity at high confining pressures, and (ⅳ) initial flaws that scale with the grain size. Predictions of stress/strain responses for a range of stress states demonstrate that the model captures the transition from deformation by micro-cracking at low triaxiality to plastic slip at high triaxialities. Moreover, natural outcomes of the model include dilation (or bulking) upon micro-cracking, as well as the increase in the shear strength of the damaged ceramic with increasing triaxiality. Cavity expansion calculations are used to extract some key physics relevant to penetration. Three domains have been identified: (ⅰ) quasi-static, where the ceramic fails due to the outward propagation of a compression damage front, (ⅱ) intermediate velocity, where an outward propagating compression damage front is accompanied by an inward propagating tensile (or spallation) front caused by the reflection of the elastic wave from the outer surface and (ⅲ) high velocity, wherein plastic deformation initiates at the inner surface of the shell followed by spalling within a tensile damage front when the elastic wave reflects from the outer surface. Consistent with experimental observations, the cavity pressure is sensitive to the grain size under quasi-static conditions but relatively insensitive under dynamic loadings.
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A scoping study is presented in order to investigate the potential of bentonite extrusion on radionuclide transport in a water-saturated planar fracture. A coupled mathematical model for an abstracted case describing the mass cons...
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A scoping study is presented in order to investigate the potential of bentonite extrusion on radionuclide transport in a water-saturated planar fracture. A coupled mathematical model for an abstracted case describing the mass conservation of radionuclides and bentonite extrusion into the fracture is established to observe the mass transport phenomena due to bentonite extrusion in the fracture domain. Results of numerical simulations are then analyzed in order to interpret the potential importance of extrusion in the near-field rock on the overall performance of the engineered barrier system (EBS). The mathematical model developed in this study for radionuclide migration incorporates spatial and temporal changes in porosity due to movement of bentonite particles. Finite element solutions have been derived for the porosity and for the radionuclide concentration. With a sufficiently strong sorption, the radionuclide is observed to be contained within the region ofbentonite extrusion, indicating that radionuclides would be retained within the extrusion region even if the waste canister fails early while bentonite is extruding in fractures. Such results imply the potential of the extrusion region to enhance performance in the EBS and warrant more rigorous modeling studies of this domain.
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We explored correlation in diet trends for five piscivorous predators that reproduce on the Pribilof Islands as illustrative of the shifting structure of the Bering Sea ecosystem. We evaluated the size and species of prey consumed...
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We explored correlation in diet trends for five piscivorous predators that reproduce on the Pribilof Islands as illustrative of the shifting structure of the Bering Sea ecosystem. We evaluated the size and species of prey consumed by adult female and juvenile northern fur seals (Callorhinus ursinus) and adults and chicks of black-legged kittiwakes (Rissa tridactyla), red-legged kittiwakes (Rissa brevirostris), thick-billed murres (Uria lomvia), and common murres (Una aalge) from data collected between July and October 1960-2000. Sample sources included stomachs from seals and seabirds collected on pelagic foraging grounds in the eastern Bering Sea, seal scats from rookeries and seabird regurgitations and whole prey from nest sites on St. Paul and St. George Islands of the Pribilof Island archipelago. Typical prey included small fish and invertebrates (≤ 20 cm for seals and ≤ 12 cm for seabirds) that concentrate along frontal boundaries of the continental shelf/slope and in the epi-pelagic zone. Squids and fishes including walleye pollock (Theragra chalcogramma), capelin (Mallotus villosus), and sand lance (Ammodytes hexapterus) were variably important in the diet of all five predators. Some prey, such as capelin, were principal in predator diets during the 1960s (seals) and into the early 1980s (seabirds), but declined or disappeared from all predator diets thereafter while others, such as walleye pollock, occurred with increasing frequency from the 1970s forward. As the number of individuals consuming walleye pollock increased, the overall volume of pollock in seabird diets declined. This decline was coincident with a decrease in the age and body size of pollock consumed by both seabirds and fur seals. Squid and pollock were negatively correlated in the diets of their primary consumers, northern fur seals (Pearson's coefficient -0.71, p = 0.016) and thick-billed murres (Pearson's coefficient = -0.74, p = 0.015) from the 1970s forward. Inter-island variation in diet was evident to varying degrees for all predators, with a prevalence offish on St. Paul Island and invertebrates on St. George Island. Bayesian time-series analysis of synthesized data described significant temporal cross-correlation in diet among northern fur seals, red- and black-legged kittiwakes, and thick-billed murres. For all correlated predators except common murres, beta-binomial modeling indicated that trends in the occurrence of four of the five primary prey (sand lance, capelin, squid, and pollock) evaluated, were significantly associated with eastern Bering Sea time-series trends in sea surface temperature, ice retreat or a combination of both. Data synthesis highlighted potential competition and a scenario for the effects of an altered prey field on the population stability of predators. The association between correlated diet changes among predators and indices of oceanographic shifts in the 1970s and the 1990s allow scrutiny of hypotheses concerning causal mechanisms in population declines.
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Operating reserve assessment has become increasingly important in the new utility environment in which ancillary services have been assigned a value. This paper presents a procedure for compulsory provision of spinning reserve usi...
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Operating reserve assessment has become increasingly important in the new utility environment in which ancillary services have been assigned a value. This paper presents a procedure for compulsory provision of spinning reserve using a risk-constrained cost-based mechanism. In this mechanism, the electrical energy and spinning reserve are dealt with simultaneously because the provision of reserve cannot be decoupled from the provision of energy. Generators are paid the opportunity cost associated with their reduced energy because compulsion is financially unattractive among them. The transmission system reliability is considered in a simplified manner when computing composite system risk. In the proposed structure, the Independent System Operator (ISO) is responsible for reliability management and is thus responsible for providing sufficient reserve on behalf of the users of the system. The method is applied to the Roy Billinton Test System (R.BTS). The General Algebraic Modeling System (GAMS Rev. 140) is used to solve the mixed integer nonlinear co-optimization problems.
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The motion of a vortex domain wall in a ferromagnetic strip of submicron width under the influence of an external magnetic field exhibits three distinct dynamical regimes. In a viscous regime at low fields the wall moves rigidly w...
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The motion of a vortex domain wall in a ferromagnetic strip of submicron width under the influence of an external magnetic field exhibits three distinct dynamical regimes. In a viscous regime at low fields the wall moves rigidly with a velocity proportional to the field. Above a critical field the viscous motion breaks down, giving way to oscillations accompanied by a slow drift of the wall. At still higher fields the drift velocity starts rising with the field again but with a much lower mobility dv/dH than in the viscous regime. To describe the dynamics of the wall, we use the method of collective coordinates that focuses on soft modes of the system. By retaining two soft modes, parametrized by the coordinates of the vortex core, we obtain a simple description of the wall dynamics at low and intermediate applied fields that applies to both the viscous and oscillatory regimes below and above the breakdown. The calculated dynamics agrees well with micromagnetic simulations at low and intermediate values of the driving field. In higher fields, additional modes become soft and the two-mode approximation is no longer sufficient. We explain some of the significant features of vortex-domain-wall motion in high fields through the inclusion of additional modes associated with the half antivortices on the strip edge.
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During three replicate studies, cream, compressed and dry yeast samples were stored for 21 days at 4, 10, 25 and 37C. At 3-day intervals, bacteria were quantified using standard plate counting procedures, and 1,044 predominant col...
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During three replicate studies, cream, compressed and dry yeast samples were stored for 21 days at 4, 10, 25 and 37C. At 3-day intervals, bacteria were quantified using standard plate counting procedures, and 1,044 predominant colonies isolated and characterized. The highest counts of aerobic bacteria and Enterococcus spp., up to 7 and 8 log colony-forming units (cfu) per mL or g, were found when cream and compressed yeast samples were exposed to elevated temperatures (25 and 37C), while lower counts (4 and 6 log cfu/mL or g) were obtained from refrigerated samples (4C). At 10C, counts of aerobic bacteria and Enterococcus spp. increased from 4 to 7 log cfu/mL or g, highlighting the importance of temperature control during the storage and distribution of perishable cream and compressed yeast. Vacuum-packaging of dry yeast reduced the growth of aerobic populations. Throughout storage, Lacto-bacilli dominated the bacterial populations in both cream and compressed yeast (45 to 78%), while Enterococcaceae predominated in vacuum-packaged dry yeast (54 to 68%), suggesting they were primarily responsible for the spoilage of commercial yeast products.
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