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The economic development in China and the rising of the living standard need to speed up the urbanisa-tion.The development of small towns is an important way to Chinese urbanization.Land use plays a very important role in the development of small towns.However there are many problems in the development of small towns,esp.in land use.The paper first discusses the land problems in the development of small towns.Such as much cultivated land lies idle,under-utilization and waste of land,increasing illegal use of land,unstable contractural relationship for land use.The relationship between the development of small towns and land use is also studied.Then the guidelines for the land system innovations of small towns are put forward.Namely the sustainability of social and economic development,the bal-ance between land reservation and land utilization,the provision of service to village ,agriculture and farmer,the manage-ment of land resource and land assets,the parsimonious andlegal use of land.The basic framework of land system innova-tions of small towns is put forward finally.It include the land replacement policy for small towns and the permanent tenan-cy of farmland,the overall plan for land uses and other plans in harmony,the establishment of a flexible system of land supplies,using land with payments ,the transfer of agricultural land and refining the land law related to the construction of small towns. 相似文献
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The magnetic-field distribution outside a flat, infinitely conductive unbounded disk in the field of a point magnetic dipole is determined. A relationship is established between the problem of magnetic-field determination and the problem of the flow of an ideal incompressible fluid around an infinitely thin disk. 相似文献
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In the atmospheric Čerenkov technique γ-rays are detected against the abundant background produced by hadronic showers. In
order to improve the signal to noise ratio of theexperiment, it is necessary to reject a significant fraction of hadronic
showers. Traditional background rejection methods based on image shape parameters have been extensively used for the data
from imaging telescopes. However, non-imaging Čerenkov telescopes have to develop very different means of statistically identifying
and removing cosmic ray events. Some of the parameters, which could be potentially important for non-imaging arrays, are the
temporal and spectral differences, the lateral distributions and density fluctuations of Čerenkov photons generated by γ-ray
and hadron primaries. Here we study the differences in fluctuations of Čerenkov photon density in the light pool at the observation
level from showers initiated by photons and those initiated by protons or heavier nuclei. The database of simulated events
for the PACT array has been used to evaluate the efficiency of the new technique. Various types of density fluctuations like
the short range and medium range fluctuations as well as flatness parameter are studied. The estimated quality factors reflect
the efficiencies with which the hadrons can be rejected from the data. Since some of these parameters are independent, the
cuts may be applied in tandem and we demonstrate that the proton rejection efficiency of ∼90% can be achieved. Use of density
fluctuations is particularly suited for wavefront sampling observations and it seems to be a good technique to improve the
signal to noise ratio.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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The kinetics of the reactions of C2H radical with ethane (k1), propane (k2), and n-butane (k3) are studied over the temperature range of T = 96-296 K with a pulsed Laval nozzle apparatus that utilizes a pulsed laser photolysis-chemiluminescence technique. The C2H decay profiles in the presence of both the alkane reactant and O2 are monitored by the CH(A2Δ) chemiluminescence tracer method. The results, together with available literature data, yield the following Arrhenius expressions: k1(T) = (0.51 ± 0.06) × 10−10 exp[(−76 ± 30)K/T] cm3 molecule−1 s−1 (T = 96-800 K), k2(T) = (0.98 ± 0.32) × 10−10exp[(−71 ± 60)K/T] cm3 molecule−1 s−1 (T = 96-361 K), and k3(T) = (1.23 ± 0.26) × 10−10 cm3 molecule−1 s−1 (T = 96-297 K). At T = 296 K, k1 is measured as a function of total pressure and has little or no pressure dependence. The results from this work support a direct hydrogen abstraction mechanism for the title reactions. Implications to the atmospheric chemistry of Titan are discussed. 相似文献
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