Population growth rate

A population is a group of individuals of one species that live in the same general area. Many factors can affect the population size and its growth rate. Population size can depend on the total amount of life a habitat can support. This is the carrying capacity of the environment. Once the habitat runs out of food, water, shelter, or space, the carrying capacity decreases, and then stabilizes. 

The urban population is based on the percentage of population in urban areas. Data on annual population growth rate, population age (with high risk in traffic) between 15-29, aged 65 and above might be added. 

Country Organization Responsible for Power Planning Population (1982) (106) Growth Rate Population (1980-2000) (Percent) Area (103Km2) Urbanization (Cities 1 million) (No./% Total Population) GNP GNP Per Capita (US ) PER CAPITA Av. Annua 1 Growth Rate (Rate %) (1960-82) Primary Energy for Electric Power (%) Nuclear Power Plans... 

Population Population change Population growth rate Population of urban formal and informal settlements... 

The formulation of a population balance requires defining growth rate as the rate of change of the characteristic dimension... 

Although evidence exists for both mechanisms of growth rate dispersion, separate mathematical models were developed for incorporating the two mechanisms into descriptions of crystal populations random growth rate fluctuations (36) and growth rate distributions (33,40). Both mechanisms can be included in a population balance to show the relative effects of the two mechanisms on crystal size distributions from batch and continuous crystallizers (41). 

If the crystallizer is now assumed to operate with a cleat feed (n = 0), at steady state (dn jdt = 0), and if the crystal growth rate G is invariant and a mean residence time T is defined as then the population balance can be written as... 

Analysis of equation 48 shows that a single sample taken either from inside the crystallizer or from the product stream will allow evaluation of nucleation and growth rates at the system conditions. Figure 12 shows a plot of typical population density data obtained from a crystallizer meeting the stated assumptions. The slope of the plot of such data maybe used to obtain the growth rate, and the product of the intercept and growth rate gives the nucleation rate. 

For systems following invariant growth the crystal population density in each size range decays exponentially with the inverse of the product of growth rate and residence time. For a continuous distribution, the population densities of the classified fines and the product crystals must be the same at size Accordingly, the population density for a crystallizer operating with classified-fines removal is given by... 

Now the speeial utility of the MSMPR population balanee model equation at steady state ean be elearly seen. Firstly, at known residenee time, t, the Growth rate, G, may be obtained from the slope (= —1/Gt) of the plot in Figure 3.7. 

The slope of population density plot enables the growth rate to be inferred, thus... 

Several authors have presented methods for the simultaneous estimation of crystal growth and nucleation kinetics from batch crystallizations. In an early study, Bransom and Dunning (1949) derived a crystal population balance to analyse batch CSD for growth and nucleation kinetics. Misra and White (1971), Ness and White (1976) and McNeil etal. (1978) applied the population balance to obtain both nucleation and crystal growth rates from the measurement of crystal size distributions during a batch experiment. In a refinement, Tavare and... 

The aim of the parameter estimation is to deduee the growth rate G, nuelea-tion rate agglomeration kernel /3aggi and disruption kernel /3disr from the experimental CSD. The CSD is deseribed mathematieally by the population balanee (Randolph and Larson, 1988)... 

With the assumption that the growth rate G is not a funetion of the partiele size (MeCabe s AL-law), for a eonstant erystallizer volume and for a erystal-free inlet flow (no seeding) the population balanee beeomes... 

Nueleation rates, whieh are ealeulated from the growth rates and the population densities at L 0 eover a range from 5.6 x 10 to 2.8 x 10" m s . Literature values for nueleation rates of ealeium oxalate monohydrate are rare Garside etal. (1982) found nueleation rates from 2.78 x lO to 8.33 x lO m s at 37 °C and 0.001 M feed eoneentration, and those ealeulated from the data of Brown etal. (1990) are between 2.78 x 10" and 2.7 x 10 m s , also at 37°C. 

An aging population and continued improvements in engine technology and fuel economy may slow U.S. gasoline demand in the early part of the twenty-first century from the 2 percent annual growth rate of the 1990s. 

A bioassay is a test designed to measure the effect of a chemical on a test population of organisms. The effect may be a physiological or biochemical parameter, such as growth rate, respiration, or enzyme activity. In the case of drilling fluids, bioassays lethality is the measured effect. 

Equation (3.14.2.9) contributes to the postulated model which is induced by an inhibition factor for the population growth rate. Assuming that the inhibition is second-order with respect to cell dry weight (x2), then the equation becomes 19... 

The logistic equation leads to a lag phase, an exponential initial growth rate and a stationary population of concentration (xm). In a population, it is often the case that the birth rate decreases as the population itself increases. The reasons may vary from increased scientific or cultural sophistication to a limited food supply. 

Once there is an appreciable amount of cells and they are growing very rapidly, the cell number exponentially increases. The optical cell density of a culture can then be easily detected that phase is known as the exponential growth phase. The rate of cell synthesis sharply increases the linear increase is shown in the semi-log graph with a constant slope representing a constant rate of cell population. At this stage carbon sources are utilised and products are formed. Finally, rapid utilisation of substrate and accumulation of products may lead to stationary phase where the cell density remains constant. In this phase, cell may start to die as the cell growth rate balances the death rate. It is well known that the biocatalytic activities of the cell may gradually decrease as they age, and finally autolysis may take place. The dead cells and cell metabolites in the fermentation broth may create... 

---