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Drought is a normal, recurring feature of the climate in most parts of china. In recent years, many researchers have found lots of drought monitoring methods with remote sensing data. In this paper, the author firstly analyze advantages and disadvantages of common drought monitoring methods, then study the drought monitoring method meeting HJ satellite condition. At last, the author use HJ data to...
Non-linear finite element simulation by an elastic-viscoplastic constitutive model and the experimental characterization were carried out to investigate the volume effect of BGA structure solder joints under shear stress. A solder mask defined flat type copper pad of a circular opening 480 μm diameter and Sn3.0Ag0.5Cu (SAC) lead-free solder balls of 300–760 μm in diameter, were used to fabricate BGA...
With the increasing miniaturization of electronic devices and products, the size of solder joints becomes smaller and smaller, the current density in the solder interconnects gets higher and higher, accordingly the electromigration (EM) has become a serious reliability issue for the solder interconnects. The studies on flip chip have shown that the configurable change of solder joints and current...
The influences of the standoff height (H), contact angle (θ), pad size and loading rate on shear fracture behavior of BGA structure Cu/Sn-3.0Ag-0.5Cu/Cu joints were investigated by finite element (FE) method. The simulation results show that the maximum Von Mises stress zones locate on the edge of the solder near the intermetallic compound (IMC) layer in the BGA joint under shear stress, the cracks...
For micro-scale solder interconnects, the micro structure of the solder joint and the soldering defects are directly related to the solidification behavior of the undercooled solder. In this study, the undercooling and solidification behavior of Sn3.0Ag0.5Cu solder balls with different diameters (0.76, 0.50 and 0.30 mm) and the joints of soldering these balls on Cu pads of two different diameters...
In recent years, the Sn-Cu-Ni lead-free solders have attracted considerable attention from electronic packaging manufactures, due to the advantage of low cost. In this study, La-Ce mixed rare earth (MRE) with three different amounts of 0.05, 0.10 and 0.25 % (wt.%) was added into the Sn-0.7Cu-0.05Ni alloy to form the Sn-0.7Cu-0.05Ni-xMRE solder, and then, the interfacial reaction and microstructure...
The interfacial micro structure and creep behavior of the single BGA structure Cu/Sn-3.0Ag-0.5Cu/Cu joint of different standoff height (i.e., solder volume) values and undergoing isothermal aging were studied by using the lap-shear test. The experimental results show that the thickness of the intermetallic compounds (IMC) layer at the solder/Cu interface increases with decreasing the standoff height...
This article mainly discuss the influence factors of the Beijing new airport freight Volume, choice the highest correlation regional economic indexes, check the previous data, verify the feasibility of the model, and the forecast the Beijing new airport freight volume in the future.
Many index factors constitute safety production assessment of coal enterprises, and most of them are fuzzy. By the method of fuzzy comprehensive evaluation, people can analyze the linkages between the various factors from both internal and external to determine the primary and secondary factors and provide advice on security rectification in order to reduce the occurrence of safety accidents. This...
Although information and Internet technology developed rapidly, how to realize flexible integration of enterprise application, and how to realize coordination of the heterogeneous information system and automation of the business process, have been core issues that need to be further researched. Application of Web Services and WS-BPEL can solve this problem. By using Web Services, which is platform-independent...
Spatial filter is the key unit of high power solid laser system for nonlinear increase control. However, the plasma closure occurred in pinhole is easily happened when long pulse running which may reduce the beam quality. The optimum design of pinhole will meet the needs for long pulse running which is important for spatial filter application. This paper based the key problems, such as suppression...
For beam passing through cavity mirror twice in multi-pass amplifier laser facility, deformable mirror is often applied at location of cavity mirror for the goal of improving correction range. However, multi-pass amplifier with U-turn for improving optical quality has its own feature different from other facilities. Beam has 90° rotation and size change between 1~2 pass and 3~4 pass propagation. A...
In 2005 the “Kyoto Protocol” for the global carbon trading laid the legal foundation, It is not only limited to the form of laws and regulations related to national greenhouse gas emissions, but also give birth to a carbon emissions-based carbon trading market. This paper investigates the relationship between the carbon finance of listed commercial banks and the financial factors, and research the...
In this paper, a transmission line model is constructed to analyze the performance of radar absorbing materials and the reflection characteristic of the resonance frequency. First, the paper introduces some kind of radar absorbing materials. Then, multilayer Jaumann absorbers are also analyzed using Smith Chart. Last, some multilayer Jaumann absorbers can be designed in the paper, which have good...
Aiming at the control complex of automobile engine control unit (ECU), a test system of the automobile engine control unit was designed. The system is composed of the input signal simulate module, measurement and control module, signal collection and disposal module, communication module etc. By means of simulating the signal of sensors, such as the crankshaft position sensor, the throttle position...
For evaluating flight delay in our country's aviation airports with the status of flight delay in civil airport, from the different influence actors of the flight delay such as airport, airline company, aviation control, travelers, meteorological condition etc. this paper used the evaluation method based on rough set theory and grey theory to build the evaluation system, tried to evaluate it. This...
Insulin pump is an effective instrument for diabetic treatment. Aiming at the high precision request and the difficulty of speed control of the insulin pump, the optical encoder and the current feedback were applied into the insulin pump to measure the rotation speed of the motor. A control scheme based on optical encoder was proposed to implement the high precision speed control of insulin pump motor...
The gas diffusion layer (GDL) of the proton exchange membrane fuel cell (PEMFC) plays a prominent effect on the water balance inside the fuel cell. A two-dimensional, steady-state, two-phase model for a PEMFC is developed to investigate the effects of GDL characteristics on the water-protect performance of the fuel cell. Analysis of the water-protect performance of low humidity PEMFC indicates that...
Based on the typhoons and precipitation data, the article aims to analyze the typhoon influence on the precipitation in Hunan Province during from 1980 to 1998. The results showed that the typhoon rainstorms appeared forty-four times and affected Hunan at different degrees from 1980 to 1998. Meanwhile, thirty-two typhoon rainstorms were induced. That is to say, about average 1.68 times of the typhoon...
After monolithic translation of superstructure, the upper structure and new foundation should be connected effectively. Installations of isolators between the topside structure and base are not only make full use of the translation material, but also enhance the security of the building. For the masonry structure of integral translation, double columns with coupling beam of the vertical bearing component...
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