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The solution of time-dependent population models

Li, Nan; Tuljapurkar, Shripad - In: Mathematical Population Studies 7 (2000) 4, pp. 311-329

We analyze the dynamics of age-structured population renewal when vital rates make a transition in a finite time interval from arbitrary initial values to any specified final values. The general solution to the renewal equation in such cases is obtained. This solution describes the birth...

Persistent link: https://www.econbiz.de/10009205484

Modelling regional population growth in China

Shen, Jianfa; Spence, Nigel - In: Mathematical Population Studies 6 (1997) 3, pp. 241-274

This paper develops a forward demographic rates-based multiregional population model on the basis of a set of multiregional population accounts. Forward emigration rates and immigration flows are adopted to describe the external migrations. The model is used to make consistent multiregional...

Persistent link: https://www.econbiz.de/10009205504

Does Malthus’s principle of population still have a practical purpose nowadays?

Ramírez Sánchez, José Carlos - Centro de Investigación y Docencia Económicas (CIDE) - 2012

By introducing a delay differential equation into a population model this paper attempts to show that an update on Malthus’s principle of population requires using new mathematical analyses involving oscillations around a stable attractor. Acceptance of the fact that Malthusian dynamic...

Persistent link: https://www.econbiz.de/10010685973

Validation and analysis of detailed kinetic models for ethylene combustion

Xu, Chaoqi; Konnov, Alexander A. - In: Energy 43 (2012) 1, pp. 19-29

Present work aims at evaluation of contemporary comprehensive detailed kinetic mechanisms for ethylene combustion … validated by extensive comparison with available experimental data on ethylene ignition and flame propagation. The experimental … differences in the predictions of ethylene ignition and flame propagation under a variety of conditions have been observed …

Persistent link: https://www.econbiz.de/10010809695

Steam cracking and methane to olefins: Energy use, CO2 emissions and production costs

Ren, Tao; Patel, Martin K.; Blok, Kornelis - In: Energy 33 (2008) 5, pp. 817-833

While most olefins (e.g., ethylene and propylene) are currently produced through steam cracking routes, they can also … to low ethylene yields and other problems. While several possibilities for energy efficiency improvement do exist, none …

Persistent link: https://www.econbiz.de/10010810563

Plastic vs. fuel: Which use of the Brazilian ethanol can bring more environmental gains?

Alvarenga, Rodrigo A.F.; Dewulf, Jo - In: Renewable Energy 59 (2013) C, pp. 49-52

hydrous ethanol as fuel for transportation and the same amount for monomer production (ethylene), and compared them with the … common practice of today in Brazil. Using ethanol to produce ethylene (instead of fossil-based ethylene) would generate … and 1.82 kg CO2eq. Some uncertainties were quantified, for instance we could observe that when the ethanol-to-ethylene …

Persistent link: https://www.econbiz.de/10011045756

A bioeconomic model of trophy hunting

Naevdal, Eric; Olaussen, Jon Olaf; Skonhoft, Anders - In: Ecological Economics 73 (2012) C, pp. 194-205

During the last few decades wildlife trophy hunting has increasingly replaced traditional meat hunting. The economics of trophy hunting is analyzed with the Scandinavian moose (Alces alces) serving as an example. A four-stage model (calf, yearlings, adult female and adult male) is formulated....

Persistent link: https://www.econbiz.de/10010576674

Two population models with constrained migrations

Normand, Raoul - In: Stochastic Processes and their Applications 124 (2014) 5, pp. 1773-1812

We study two models of population with migration. On an island lives an individual whose genealogy is given by a critical Galton–Watson tree. If its offspring ends up consuming all the resources, any newborn child has to migrate to find new resources. In this sense, the migrations are...

Persistent link: https://www.econbiz.de/10010875061

Does Malthus’s principle of population still have a practical purpose nowadays?

Ramírez Sánchez, José Carlos - Centro de Investigación y Docencia Económicas (CIDE) - 2012

Persistent link: https://www.econbiz.de/10010823254

Causes of Square and Boll Shedding in Cotton

Guinn, Gene - Economic Research Service, Department of Agriculture - 1982

Persistent link: https://www.econbiz.de/10010921861