混凝土板梁的有限条法简化分析

桥梁结构在各种荷载作用下产生的内力和弯矩影响着桥梁的性能.桥梁弯曲、扭转和挠度等过大时会导致结构的破坏,这在结构设计阶段就应加以分析.本文提出一种有限条简化分析方法,可以较好地分析桥梁的挠度、弯曲和扭转变形.通过对一座简支板梁桥模型的分析,与现行有限元方法的分析结果进行了比较.结果表明,本方法能够较好地处理边界条件,只需要很少的输入工作就可以得到正确的分析结果,从而为结构工程师提供了一种用于分析板梁桥在交通荷载作用下行为的有效工具.     

Further evidence for small-bodied hominins from the Late Pleistocene of Flores, Indonesia

Homo floresiensis was recovered from Late Pleistocene deposits on the island of Flores in eastern Indonesia, but has the stature, limb proportions and endocranial volume of African Pliocene Australopithecus. The holotype of the species (LB1), excavated in 2003 from Liang Bua, consisted of a partial skeleton minus the arms. Here we describe additional H. floresiensis remains excavated from the cave in 2004. These include arm bones belonging to the holotype skeleton, a second adult mandible, and postcranial material from other individuals. We can now reconstruct the body proportions of H. floresiensis with some certainty. The finds further demonstrate that LB1 is not just an aberrant or pathological individual, but is representative of a long-term population that was present during the interval 95-74 to 12 thousand years ago. The excavation also yielded more evidence for the depositional history of the cave and for the behavioural capabilities of H. floresiensis, including the butchery of Stegodon and use of fire.     

An intense stratospheric jet on Jupiter

The Earth's equatorial stratosphere shows oscillations in which the east-west winds reverse direction and the temperatures change cyclically with a period of about two years. This phenomenon, called the quasi-biennial oscillation, also affects the dynamics of the mid- and high-latitude stratosphere and weather in the lower atmosphere. Ground-based observations have suggested that similar temperature oscillations (with a 4-5-yr cycle) occur on Jupiter, but these data suffer from poor vertical resolution and Jupiter's stratospheric wind velocities have not yet been determined. Here we report maps of temperatures and winds with high spatial resolution, obtained from spacecraft measurements of infrared spectra of Jupiter's stratosphere. We find an intense, high-altitude equatorial jet with a speed of approximately 140 m s(-1), whose spatial structure resembles that of a quasi-quadrennial oscillation. Wave activity in the stratosphere also appears analogous to that occurring on Earth. A strong interaction between Jupiter and its plasma environment produces hot spots in its upper atmosphere and stratosphere near its poles, and the temperature maps define the penetration of the hot spots into the stratosphere.     

Determining hydrocarbon prospective zone using the combination of qualitative analysis and fuzzy logic method

Hydrocarbon prospective zone is a certain layer in a reservoir which is estimated producing oil. The geologists use the qualitative analysis method to find the prospect layers. The research used five variables modeled by three fuzzy membership functions and eight rules of fuzzy logic. The rules cause insensitiveness in the working system. This study therefore was conducted by modeling each of input variables into different models using 36 rules. It aims to determine the existence of hydrocarbon prospective zone through a qualitative analysis in a reservoir using fuzzy inference system with Mamdani method. The data were taken from well log data in reservoir “X”. There were some steps in doing this study, including fuzzification, inference system, and defuzzification. The result showed 99 prospect layers from 3000 layers in reservoir “X” with 97.7% of accuracy.     

Nanotube electronics: large-scale assembly of carbon nanotubes

Nanoscale electronic devices made from carbon nanotubes, such as transistors and sensors, are much smaller and more versatile than those that rely on conventional microelectronic chips, but their development for mass production has been thwarted by difficulties in aligning and integrating the millions of nanotubes required. Inspired by biomolecular self-assembly processes, we have created chemically functionalized patterns on a surface, to which pre-grown nanotubes in solution can align themselves in huge numbers. This method allows wafer-scale fabrication of millions of carbon-nanotube circuits with single-nanotube precision, and may enable nanotube-based devices, such as computer chips and high-density sensor arrays, to be produced industrially.     

Temperature-sensitive mutant of avian erythroblastosis virus suggests a block of differentiation as mechanism of leukaemogenesis.

A temperature sensitive mutant has been isolated for the first time from a replication defective acute leukaemia virus, AEV. In vivo, at 41 degrees C, the mutant shows a reduced leukaemogenic potential. In vitro, in erythroblasts transformed at 35 degrees C, haemoglobin synthesis can be induced by a shift to 41 degrees C. This indicates that the continuous expression of a viral gene product is necessary to maintain the undifferentiated state of the virus-transformed leukaemia cells.     

A flat Universe from high-resolution maps of the cosmic microwave background radiation

The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73 K cosmic microwave background. Tiny inhomogeneities in the early Universe left their imprint on the microwave background in the form of small anisotropies in its temperature. These anisotropies contain information about basic cosmological parameters, particularly the total energy density and curvature of the Universe. Here we report the first images of resolved structure in the microwave background anisotropies over a significant part of the sky. Maps at four frequencies clearly distinguish the microwave background from foreground emission. We compute the angular power spectrum of the microwave background, and find a peak at Legendre multipole Ipeak = (197 +/- 6), with an amplitude delta T200 = (69 +/- 8) microK. This is consistent with that expected for cold dark matter models in a flat (euclidean) Universe, as favoured by standard inflationary models.