MODEL B-I FOR MACRO RECTANGULAR ELEMENT AND PROBLEMS OF INFLUENCE SURFACE FOR PLATE STRUCTURES

Model B-I for marco rectangular element is presented for the first time in this paper. To establish the influence surf ace for resultant R of bending plates, a number of generalized distributive loads q are defined. It is shown by numerical examples that Model B-I and the formula for the generalized distributive loads advanced in this paper are featured by high accuracy, low memory space and flexibility in practical application, and that they are especially effective for plate structures subject to moving loads, such as the two-dimensional continuous plates of highway bridges and the flat stabs in piled jetty engineering.

Influence of Al Preflow Time on Surface Morphology and Quality of AlN and GaN on Si(111) Grown by MOCVD

We investigate the influence of A1 preflow time on surface morphology and quality of AIN and GaN. The AIN and GaN layers are grown on a Si （111） substrate by metal organic chemical vapor deposition. Scanning electron microscopy, atomic force microscopy, x-ray diffraction and optical microscopy are used for analysis. Consequently, we find significant differences in the epitaxial properties of AlN buffer and the GaN layer, which are dependent on the AI preflow time. A1 preflow layers act as nucleation sites in the case of AiN growth. Compact and uniform AIN nucleation sites are observed with optimizing A1 preflow at an early nucleation stage, which will lead to a smooth AIN surface. Trenches and AlN grain clusters appear on the AIN surface while meltoback etching occurs on the GaN surface with excessive A1 preflow. The GaN quality variation keeps a similar trend with the AIN quality, which is influenced by AI preflow. With an optimized duration orAl preflow, crystal quality and surface morphology of AIN and GaN could be improved.

Teleconnected Influence of the Boreal Winter Antarctic Oscillation on the Somali Jet： Bridging Role of Sea Surface Temperature in Southern High and Middle Latitudes

The teleconnection impact of the boreal winter Antarctic Oscillation（AAO） on the Somali Jet（SMJ） intensity in the following spring and summer is examined in this paper.The variability of the boreal winter AAO is positively related to the SMJ intensity in both spring and summer.The analyses show that the SST in southern high and middle latitudes seems to serve as a bridge linking these two systems.When the AAO is in strong positive phase,SST over the Southern Ocean cools in the high latitudes and warms in the middle latitudes,which persists into summer;however,the variability of SST in southern high and middle latitudes is also closely correlated to SMJ intensity.A possible mechanism that links SST variability with the AAO-SMJ relationship is also discussed.The AAO in boreal winter produces an SST anomaly pattern in southern high and middle latitudes through the air-sea coupling.This AAOrelated SST anomaly pattern modulates the local Ferrel cell anomaly in summer,followed by the regional Hadley cell anomaly in tropics.The anomalous vertical motion in tropics then changes the land-sea thermal contrast between the tropical Indian Ocean and the Asian continent through the variability of low cloud cover and downward surface longwave radiation flux.Finally,the land-sea thermal contrast anomaly between the tropical Indian Ocean and the Asian continent changes the SMJ intensity.The results from Community Atmosphere Model experiments forced by the SST anomaly in southern high and middle latitudes also confirm this diagnostic physical process to some extent.

The influence of the surface heat fluxes of the Kuroshio key-area on meiyu rainfall in the Changjiang River region

On the basis, of the surface heat fluxes of the Kuroshio key-area (26°-30°N, 125°-30°E)in March andApril, the climatologicai influence of the Kuroshio heat fluxes on meiyu rainfall in the Changjiang River (Yangtse River) region are studied. The results are concluded as follows;the surface heat fluxes of the Kuroshio key-area have certain influence on meiyu rainfall in the Changjiang River region during June and July. The correctness rates for the five stations in the Changjing River region (i. e. Wuhan, Jiujiang, Anqing,Nanjing and Shanghai)are in the range of 9/20-13/20. The surface heat fluxes influence mainly on the homogeneous rainfall pattern,the correctness rates come to 7/10-8/10 for the lower valley of the Changjiang River. The estimation expression of the meiyu rainfall for Shanghai consisting of the surface heat flux and the sea surface temperature anomaly of the Kuroshio key area agrees well with the actual meiyu rainfall condition.

Influence of substrate process tolerances on transmission characteristics of frequency-selective surface

Frequency-selective surface （FSS） is a two-dimensional periodic structure consisting of a dielectric substrate and the metal units （or apertures） arranged periodically on it. When manufacturing the substrate, its thickness and dielectric constant suffer process tolerances. This may induce the center frequency of the FSS to shift, and consequently influence its characteristics. In this paper, a bandpass FSS structure is designed. The units are the Jerusalem crosses arranged squarely. The mode-matching technique is used for simulation. The influence of the tolerances of the substrate＇s thickness and dielectric constant on the center frequency is analyzed. Results show that the tolerances of thickness and dielectric constant have different influences on the center frequency of the FSS. It is necessary to ensure the process tolerance of the dielectric constant in the design and manufacturing of the substrate in order to stabilize the center frequency.

Analytical formula of rectangular surface mobility of an infinite plate and the parameters influences

This paper investigates the characteristics of surface mobility when power transmission over the contact area between sub-structures is considered. An analytical formula of the surface mobility of an infinite homogeneous plate over a rectangular contact area subject to a uniform, conphase force excitation is derived by using complex power method and the concept of structural intensity. This formula provides a theoretical tool for investigating power transmission over the contact area between sub-structures. The influences of the size, the dimension and the aspect ratio of the contact area on power transmission are analyzed and described according to the results calculated, that provides an effectively theoretical method for investigation of vibration isolation.

A qualitative correlation between friction coefficient and steel surface wear in linear dry sliding contact to polymers with SGF

In this paper we tried to present a qualitative correlation,based on extensive experimental determinations between the value and the evolution of the friction coefficient,wear,and contact temperature,in the case of linear dry contact,for thermoplastic material reinforced with short glass fibers(SGF)and various steel surfaces.The aim was to highlight the evolution of the wear process depending on the evolution of the friction coefficient.As a result,it was possible to graphically illustrate the evolution of the friction coefficient and the change of the wear process,emphasizing the abrasive,adhesive and corrosive wear.The evolution of the plastic material transfer function of the contact temperature,namely of the power lost by friction(product between the contact pressure and sliding speed,p and v)was aimed and it was highlighted.It has been demonstrated that in the case of a 30%SGF content it can reach and even exceed contact temperatures very close to the flow limit of the plastic material.We tried,believing successfully,the graphic illustration of the evolution of the steel surface wear and of the contact temperature,depending on the friction coefficient.The influence of the normal load and sliding speed was evaluated in detail,but also the influence of the metallic surface roughness on the friction coefficient was discussed.